JP6972084B2 - Vacuum cleaner - Google Patents

Description

The present invention relates to a vacuum cleaner.

A vacuum cleaner including a power storage device and an electric blower that receives electric power from the power storage device to generate a suction force is known. For example, Japanese Patent Application Laid-Open No. 2015-342 (Patent Document 1) discloses an electric vacuum cleaner including a motor for driving an impeller of a suction source by receiving electric power from a battery. According to this, an inverter is provided between the battery and the motor. The inverter converts the DC voltage supplied from the battery into an AC voltage for driving the motor.

In the above-mentioned vacuum cleaner, when the motor is driven at a high rotation speed, the counter electromotive force increases and the induced voltage increases, so that the voltage (required voltage) to be applied to the motor increases. Therefore, so-called voltage saturation may occur in which this required voltage exceeds the outputable voltage of the inverter.

In response to such voltage saturation, for example, Japanese Patent Application Laid-Open No. 2004-135835 (Patent Document 2) describes an electric vacuum cleaner configured to increase the output voltage of an inverter by using a boost converter. Is disclosed.

JP-A-2015-342 Japanese Unexamined Patent Publication No. 2004-135835

The electric vacuum cleaner described in Patent Document 2 is configured to switch between a non-boosting operation mode in which the boost converter is not operated and a boosting operation mode in which the boost converter is operated. In the non-boost operation mode, the electric blower is driven by the output voltage of the battery. On the other hand, in the boost operation mode, the electric blower is driven by the output voltage boosted by the boost converter. In Patent Document 2, the non-boosting operation mode is set when the weak operation button is operated, and the boosting operation mode is set when the strong operation button is operated.

In a configuration for driving an electric blower by converting the output voltage of the boost converter into an AC voltage by an inverter as disclosed in Patent Document 2, each component of the electric vacuum cleaner is used according to the voltage level of the output voltage of the boost converter. Power loss changes. Therefore, the efficiency of the entire vacuum cleaner also changes.

However, Patent Document 2 does not disclose or suggest controlling the boost converter in consideration of the efficiency of the entire vacuum cleaner.

Therefore, a main object of the present invention is to realize high efficiency in a vacuum cleaner equipped with an electric blower that receives electric power from a power storage device.

A vacuum cleaner according to a certain aspect of the present invention is equipped with an electric blower that generates a suction force. The vacuum cleaner includes an AC motor, a power storage device, a boost converter, an inverter, and a control device. The AC motor is configured to drive an electric blower. The boost converter is configured to boost the DC voltage received from the power storage device. The inverter is configured to convert the output voltage of the boost converter into an AC voltage for driving the AC motor. The control device is configured to control the boost converter and the inverter. The boost converter is configured to selectively perform boosting operation and non-boosting operation. The boosting operation is an operation in which the boosting rate indicated by the ratio of the output voltage to the voltage of the power storage device is made higher than 1. The non-boosting operation is an operation in which the boosting rate is fixed at 1. When generating the required suction force in the electric blower, the control device selects the first power loss that occurs in the electric vacuum cleaner when the booster operation is selected to drive the AC motor, and the non-boost operation is selected for the AC motor. The second power loss that occurs in the electric vacuum cleaner when driving is calculated. When the first power loss is greater than the second power loss, the controller controls the boost converter and inverter to perform a non-boost operation to drive the AC motor. On the other hand, when the first power loss is smaller than the second power loss, the control device controls the boost converter and the inverter so as to perform a boosting operation to drive the AC motor.

According to a certain aspect of the present invention, high efficiency can be realized in an electric vacuum cleaner equipped with an electric blower that receives electric power from a power storage device.

It is a figure which shows the whole structure of the vacuum cleaner according to Embodiment 1 of this invention. It is a block diagram which shows the structure of a power-source part. It is a circuit diagram which shows the structure of a boost converter and an inverter. FIG. 3 is a functional block diagram illustrating a control configuration relating to control of a boost converter in a vacuum cleaner according to the first embodiment. It is a flowchart explaining the control of the boost converter in the vacuum cleaner according to Embodiment 1. FIG. It is a figure explaining the control of the boosting rate at the time of boosting operation. FIG. 3 is a functional block diagram illustrating a control configuration relating to control of a boost converter in a vacuum cleaner according to the second embodiment. It is a flowchart explaining the boosting rate control in the vacuum cleaner according to Embodiment 2. FIG. 3 is a functional block diagram illustrating a control configuration relating to control of a boost converter in a vacuum cleaner according to the third embodiment. It is a figure for demonstrating the temperature rise operation performed by a control device. It is a flowchart explaining the temperature raising operation performed in the vacuum cleaner according to Embodiment 3.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are designated by the same reference numerals and the description thereof will not be repeated.

Embodiment 1.
(Vacuum cleaner configuration)
FIG. 1 is a diagram showing an overall configuration of a vacuum cleaner 100 according to the first embodiment of the present invention. 1 (A) is a front view of the vacuum cleaner 100, and FIG. 1 (B) is a side view of the vacuum cleaner 100.

FIG. 1 shows a stick cleaner as an example of the vacuum cleaner 100. The electric vacuum cleaner 100 is not limited to the stick cleaner, and may be, for example, a canister type vacuum cleaner configured by connecting an extension pipe to a vacuum cleaner main body having an electric blower, a dust collecting unit, and a power supply unit.

With reference to FIG. 1A, the vacuum cleaner 100 includes a power supply unit 104, an electric blower 106, a dust collecting chamber 108, an extension pipe 111, and a suction unit 112. The power supply unit 104, the electric blower 106, and the dust collecting chamber 108 are housed in the housing 110. A handle 102 is connected to one end of the housing 110. An extension tube 111 is connected to the other end of the housing 110.

The power supply unit 104 includes the battery B and the substrate 116. The battery B is shown as a representative example of a power storage device configured to be rechargeable. The battery B is, for example, a secondary battery such as a nickel hydrogen battery or a lithium ion battery. As the power storage device, it is also possible to use an electric double layer capacitor or the like.

As will be described later, the substrate 116 realizes a motor drive device for driving the electric blower 106 using the electric power stored in the battery B. The substrate 116 includes a power conversion device for converting the DC power supplied from the battery B into AC power for driving the electric blower 106.

The electric blower 106 is arranged on the ventilation passage 113 provided in the housing 110. The electric blower 106 receives electric power from the battery B and sucks it into the ventilation passage 113 to apply a negative pressure. The electric blower 106 drives an AC motor (see FIG. 2) as a blower motor.

The dust collecting chamber 108 communicates with the extension pipe 111. The suction portion 112 is connected to the tip end portion of the extension pipe 111. The suction unit 112 sucks dust on the surface to be cleaned from the suction port 114.

When the AC motor is driven, the electric blower 106 generates a suction negative pressure. Due to this suction negative pressure, dust on the surface to be cleaned is sucked into the suction portion 112 together with air. The air containing the dust is conveyed to the dust collecting chamber 108 through the extension pipe 111. Dust in the air is collected in the dust collecting chamber 108. The air collected with dust passes through the ventilation passage 113, passes through a filter (not shown), and then reaches the electric blower 106. After that, the air is discharged to the outside of the housing 110 from the exhaust port through the ventilation passage 113.

The handle 102 is provided with an operation unit 13 and a display unit 14. The operation unit 13 includes a plurality of operation switches for driving the electric blower 106 by a motor drive device described later. The plurality of operation switches include an operation switch for starting or stopping suction cleaning, and an operation switch for switching various operation modes. The operation switch for switching the operation mode includes an operation switch for switching the suction force generated in the electric blower 106, for example, strong operation, medium operation, and weak operation.

The display unit 14 displays the operating state (operation mode, battery B state (charging state), etc.) of the vacuum cleaner 100. As will be described later, the display unit 14 is configured to display to that effect when the operation is stopped in order to prevent the battery B from overheating. Further, the display unit 14 is configured to display to that effect when the temperature raising operation for raising the temperature of the battery B is executed at the time of starting the vacuum cleaner 100. The display unit 14 is not limited to the form installed on the handle 102, and may be provided at another position.

(Structure of power supply unit)
Next, the configuration of the power supply unit 104 in FIG. 1 will be described with reference to FIGS. 2 and 3.

With reference to FIG. 2, the substrate 116 is provided between the battery B and the AC motor 4 of the electric blower 106, and constitutes a motor drive device that receives power from the battery B to drive the AC motor 4. do.

Specifically, the substrate 116 includes a power switch 6, a boost converter 2, an inverter 3, and a control device 5. The power switch 6 is provided between the battery B and the boost converter 2. The power switch 6 is on / off controlled based on the control signal φs1 from the control device 5. The power switch 6 electrically connects the battery B to the boost converter 2 in the on (conducting) state, and electrically disconnects the battery B from the boost converter 2 in the off (disconnect) state. When the operation switch for starting the suction cleaning is operated in the operation unit 13, the power switch 6 is turned on, and when the operation switch for stopping the suction cleaning is operated, the power switch 6 is turned off.

The boost converter 2 controls the output voltage (= voltage between the positive electrode line PL2 and the negative electrode line NL) Vdc according to the voltage command value Vdc * based on the control signal φc from the control device 5. The boost converter 2 controls the output voltage Vdc in the range of Vdc ≧ VB with respect to the voltage VB of the battery B. That is, the boost converter 2 has a function of boosting the voltage VB of the battery B.

The inverter 3 is connected between the boost converter 2 and the AC motor 4. The inverter 3 is configured to convert the output voltage Vdc of the boost converter 2 into an AC voltage for driving the AC motor 4 based on the control signal φi from the control device 5. For example, the control device 5 generates a control signal φi so that the output torque of the AC motor 4 is controlled according to the torque command value.

The AC motor 4 is, for example, a three-phase permanent magnet type synchronous motor including a rotor in which a permanent magnet is embedded. The AC motor 4 is configured such that one end of three coils (not shown) of the U, V, and W phases is commonly connected to the neutral point. The AC motor 4 generates torque for rotationally driving the electric blower 106. In the example of FIG. 2, the AC motor 4 is composed of a three-phase AC motor, but may be a single-phase AC motor.

FIG. 3 is a circuit diagram showing the configurations of the boost converter 2 and the inverter 3.

With reference to FIG. 3, the boost converter 2 is configured by a so-called boost chopper circuit. Specifically, the boost converter 2 includes a reactor L1, a semiconductor switching element (hereinafter, also simply referred to as “switching element”) Q7, diodes D7 and D8, a capacitor C1, and a bypass switch 16.

One end of the reactor L1 is connected to the positive electrode line PL1 and the other end is connected to the anode of the diode D8. The cannula of the diode D8 is connected to the positive electrode line PL2. In the switching element Q7, the collector is connected to the connection node of the reactor L1 and the diode D8, and the emitter is connected to the negative electrode line NL. The diode D7 is connected in antiparallel to the switching element Q7. The on / off of the switching element Q7 is controlled by the control signal φc from the control device 5. The capacitor C1 is connected between the positive electrode line PL2 and the negative electrode line NL. The capacitor C1 smoothes the AC component of the voltage fluctuation between the positive electrode line PL2 and the negative electrode line NL.

The bypass switch 16 is electrically connected in parallel with the reactor L1. The bypass switch 16 is on / off controlled based on the control signal φs2 from the control device 5. In the on state, the bypass switch 16 bypasses the reactor L1 and connects the positive electrode line PL1 to the anode of the diode D8.

The boost converter 2 is configured to selectively execute boosting operation and non-boosting operation. In the boost operation, the boost converter 2 is controlled to turn on / off the switching element Q7. Specifically, during the on-period Ton of the switching element Q7, energy is stored in the reactor L1 by forming a current path via the battery B-reactor L1-switching element Q7. On the other hand, in the off period Tof of the switching element Q7, a current path is formed via the battery B-reactor L1-diode D8-capacitor C1. As a result, the energy stored in the reactor L1 during the on-period ton is supplied to the capacitor C1. In this way, the voltage VB of the battery B is boosted and output between the positive electrode line PL2 and the negative electrode line NL.

The boost converter 2 can control the boost rate by controlling the duty ratio of the switching element Q7 (the ratio of the on-period Ton to the switching cycle T (= Ton + Toff)). The boost rate is indicated by the ratio of the output voltage Vdc of the boost converter 2 to the voltage VB of the battery B (= Vdc / VB).

The control device 5 controls the on / off of the switching element Q7 according to the duty ratio calculated according to the detected values of the voltages VB and Vdc and the voltage command value Vdc *. Specifically, when the output voltage Vdc is lower than the voltage command value Vdc *, the output voltage Vdc can be increased by increasing the duty ratio. On the other hand, when the output voltage Vdc is higher than the voltage command value Vdc *, the voltage Vdc can be lowered by reducing the duty ratio. As described above, in the boosting operation, Vdc *> VB is set, and the boosting rate can be made higher than 1 by the on / off control of the switching element Q7.

On the other hand, in the non-boost operation, the AC motor 4 is controlled in the state of Vdc = VB without boosting by the boost converter 2. That is, in the non-boosting operation, the boosting rate is fixed at 1. In the non-boost operation, the switching element Q7 is fixed to off, so that the power loss in the boost converter 2 is reduced.

In non-boost operation, the bypass switch 16 is further fixed on. As a result, the voltage VB of the battery B is supplied to the inverter 3 through the bypass switch 16 and the diode D8. By sending a current to the inverter 3 without passing through the reactor L1, the power loss in the boost converter 2 is further reduced as compared with the above-mentioned fixed off switching element Q7.

The inverter 3 has a circuit configuration of a three-phase inverter. The inverter 3 includes a U-phase arm, a V-phase arm, and a W-phase arm connected in parallel between the positive electrode line PL2 and the negative electrode line NL. The U-phase arm includes switching elements Q1 and Q2 connected in series between the positive electrode line PL2 and the negative electrode line NL. The V-phase arm includes switching elements Q3 and Q4 connected in series between the positive electrode line PL2 and the negative electrode line NL. The W-phase arm includes switching elements Q5 and Q6 connected in series between the positive electrode line PL2 and the negative electrode line NL. The intermediate point of each phase arm is connected to each phase coil of the AC motor 4.

When the DC voltage Vdc is supplied from the boost converter 2, the inverter 3 converts the DC voltage Vdc into an AC voltage by the switching operation of the switching elements Q1 to Q6 in response to the control signal φi from the control device 5, and is an AC electric motor. 4 is driven.

As the switching elements Q1 to Q7, for example, an IGBT (Insulated Gate Bipolar Transistor), a MOS (Metal Oxide Semiconductor) transistor, or the like can be used. Diodes D1 to D7 are connected in antiparallel to the switching elements Q1 to Q7, respectively.

As a material constituting each switching element, a wide bandgap semiconductor having a larger bandgap than silicon can be adopted. The wide bandgap semiconductor is preferably either silicon carbide, gallium nitride based material or diamond.

Returning to FIG. 2, the power supply unit 104 further includes voltage sensors 7, 8, 9, current sensors 10, 11, temperature sensors 12, and rotation angle sensors 15.

The voltage sensor 7 detects the voltage VB of the battery B (hereinafter, also referred to as the battery voltage), and outputs the detected value to the control device 5. The voltage sensor 8 detects the output voltage Vdc of the boost converter 2 and outputs the detected value to the control device 5. The output voltage Vdc corresponds to the DC link voltage of the inverter 3. The voltage sensor 9 detects the voltage Vm applied to the AC motor 4 (hereinafter, also referred to as a motor voltage), and outputs the detected value to the control device 5.

The current sensor 10 detects the current IB (hereinafter, also referred to as battery current) flowing through the battery B, and outputs the detected value to the control device 5. The temperature sensor 12 detects the temperature TB of the battery B (hereinafter, also referred to as the battery temperature), and outputs the detected value to the control device 5. The current sensor 11 detects the current Im (hereinafter, also referred to as motor current) flowing through the AC motor 4, and outputs the detected value to the control device 5.

The rotation angle sensor 15 detects the rotor rotation angle θ of the AC motor 4 and outputs the detected value to the control device 5. The control device 5 can calculate the rotation speed Nm of the AC motor 4 based on the rotation angle θ. The rotation angle sensor may be omitted by directly calculating the rotation angle θ from the motor voltage Vm or the motor current Im.

The control device 5 is configured based on a processor including a CPU (Central Processing Unit) and a memory (not shown), and performs arithmetic processing using the detection values of each sensor based on the map and the program stored in the memory. It is configured as follows. Alternatively, at least a part of the control device 5 may be configured to execute a predetermined numerical / logical operation process by hardware such as an electronic circuit.

The control device 5 controls the boost converter 2 and the inverter 3 based on the operation command input from the operation unit 13, the detection value of each sensor, and the like. That is, the control device 5 generates control signals φc and φs2 based on the operation command and the detection value of each sensor and outputs them to the boost converter 2. Further, the control device 5 generates a control signal φi based on the operation command and the detection value of each sensor and outputs the control signal φi to the inverter 3.

Here, as described above, the boost converter 2 is configured to selectively execute the boosting operation and the non-boosting operation. The control device 5 selectively executes the boosting operation and the non-boosting operation for the control of the boost converter 2 according to the power loss generated in the vacuum cleaner 100. Hereinafter, the control of the boost converter 2 in the control device 5 will be described.

(Control of boost converter)
FIG. 4 is a functional block diagram illustrating a control configuration relating to control of the boost converter 2 in the vacuum cleaner 100 according to the first embodiment. Each functional block described in the functional block diagram described below, including FIG. 4, is realized by hardware-like or software-like processing by the control device 5.

With reference to FIG. 4, the control device 5 includes a power loss calculation unit 20, a voltage command value generation unit 22, and a switching control unit 24.

Upon receiving an operation command from the operation unit 13, the power loss calculation unit 20 is required to generate a suction force (hereinafter, also referred to as “required suction force”) specified by the operation command in the electric blower 106. Set the output (rotational speed x torque) of the AC motor 4.

For example, when the operation switch for setting the strong operation is operated in the operation unit 13, the power loss calculation unit 20 sets the output request to the AC motor 4 to the output corresponding to the strong operation mode. On the other hand, when the operation switch for setting the medium operation is operated in the operation unit 13, the power loss calculation unit 20 sets the output request to the output corresponding to the medium operation mode. Further, when the operation switch for setting the weak operation is operated in the operation unit 13, the power loss calculation unit 20 sets the output request to the output corresponding to the weak operation mode. The output request in the weak operation mode is the smallest, and the output request in the strong operation mode is the largest.

When an output request to the AC motor 4 is set in response to an operation command of the operation unit 13, the power loss calculation unit 20 calculates a voltage command value Vdc * corresponding to the set output request.

In the AC motor 4, when the rotation speed and / or the torque increases, the counter electromotive force increases and the induced voltage increases, so that the required voltage increases. Along with this, the output voltage Vdc of the boost converter 2 needs to be set higher than this required voltage. On the other hand, there is a limit to the boosting of the boost converter 2, and there is an upper limit to the output voltage Vdc. Therefore, the power loss calculation unit 20 sets the voltage command value Vdc * within the voltage range from the required motor voltage (induced voltage) to the maximum output voltage of the boost converter 2. The voltage command value Vdc * is set higher than the battery voltage VB (Vdc *> VB). That is, the boost converter 2 executes the boost operation.

The larger the output requirement for the AC motor 4, the higher the required motor voltage (induced voltage). Therefore, the required motor voltage corresponding to the output requirement in the strong operation mode is higher than the required motor voltage corresponding to the output requirement in the weak operation mode. If the operation mode is such that the required voltage of the motor is equal to or less than the battery voltage VB, the output voltage Vdc can be set to the battery voltage VB. That is, the boost converter 2 can execute the non-boost operation.

Next, the power loss calculation unit 20 estimates the power loss Plus in the vacuum cleaner 100 when the AC motor 4 is driven according to the output request.

In the estimation of the power loss Plus, the power loss calculation unit 20 selects the boosting operation to drive the AC motor 4, and the power loss in the electric vacuum cleaner 100 is Plus1 (hereinafter, also referred to as “power loss during boosting”). .) Is calculated. The boosted power loss Plus 1 corresponds to the power loss in the vacuum cleaner 100 when the voltage command value Vdc * is set higher than the voltage VB of the battery B.

Further, the power loss calculation unit 20 calculates the power loss Plus 2 (hereinafter, also referred to as “non-boost power loss”) that occurs in the vacuum cleaner 100 when the non-boost operation is selected and the AC motor 4 is driven. .. The non-boost power loss Plus 2 corresponds to the power loss in the vacuum cleaner 100 when the voltage command value Vdc * = VB is set.

Next, the calculation of the boosted power loss Plus1 and the non-boosted power loss Plus2 will be described in detail.

[1] Calculation of Power Loss at Boost 1 The power loss calculation unit 20 selects the boost operation to drive the AC electric motor 4, the power loss Pbat in the battery B, the power loss Pcon in the boost converter 2, and the power in the inverter 3. The power loss Ploss 1 at the time of boosting is calculated by summing the loss Pinv and the power loss Pmot in the AC electric motor 4. That is, the boosted power loss Plus1 is expressed by the following equation.

Plus1 = Pbat + Pcon + Pinv + Pmot ... (1)
The power loss calculation unit 20 calculates each of the power losses Pbat, Pcon, Pinv, and Pmot by the method shown below using the voltage command value Vdc * and the detection value of each sensor.

The power loss Pbat in the battery B is mainly the Joule loss in the internal resistance, and is represented by Rbat · IB2 using the internal resistance value Rbat and the battery current IB. The internal resistance value Rbat changes depending on the battery temperature TB. Generally, the lower the battery temperature TB, the higher the internal resistance value Rbat.

Here, the battery current IB during boosting operation is the average current (DC component) superimposed with the ripple current (AC component). The ripple current increases according to the voltage difference | Vdc-VB | between the output voltage Vdc and the battery voltage VB.

The power loss Pbat is represented by the sum of the power loss proportional to the square of the average current and the power loss proportional to the square of the ripple current. Of these, the power loss proportional to the square of the average current corresponds to the output power of the battery B, that is, the power supplied to the AC motor 4, and therefore does not change depending on the output voltage Vdc. On the other hand, the power loss proportional to the square of the ripple current increases as the voltage difference | Vdc-VB | increases.

Therefore, for the power loss Pbat, the power loss Pbat with respect to the voltage command value Vdc * can be calculated by creating a map in advance with the battery temperature TB and the voltage difference | Vdc-VB | as parameters.

The power loss Pcon in the boost converter 2 is mainly the sum of the switching loss Pconsw in the switching element Q7 and the loss Pconline due to the wiring impedance including the reactor L1 (Pcon = Pconsw + Pconline). The wiring impedance is determined by the material (resistivity), cross-sectional area, and wiring length of the wiring constituting the boost converter 2.

The switching loss Pconsw is expressed as the product of the power loss per switching and the switching frequency. That is, the switching loss Pconsw becomes a value proportional to the switching frequency and increases as the switching frequency increases. Further, under the same switching frequency, the switching voltage of the switching element Q7 increases as the output voltage Vdc increases, so that the switching loss Pconsw increases.

The loss Pconline due to the wiring impedance increases as the passing current (that is, battery current IB) of the boost converter 2 increases and the output voltage Vdc increases. As the ripple current in the battery current IB increases, the loss depending on the square of the current increases, so that the loss Pconline changes depending on the voltage difference | Vdc-VB |.

Therefore, the power loss Pcon depends on the switching frequency and the square of the battery current IB. As described above, the average current of the battery current IB does not change depending on the output voltage Vdc. Therefore, as the power loss Pcon, the ripple current, that is, the voltage difference | Vdc-VB | may be mainly considered. Therefore, the power loss Pcon with respect to the voltage command value Vdc * can be calculated by creating a map in advance with the switching frequency and the voltage difference | Vdc-VB | of the boost converter 2 as parameters.

The power loss Pinv in the inverter 3 is mainly the sum of the switching loss Pinvsw in the switching elements Q1 to Q6 and the loss Pinvline due to the wiring impedance (Pinv = Pinvsw + Pinvline). The wiring impedance is determined by the material (resistivity), cross-sectional area, and wiring length of the wiring constituting the inverter 3.

The switching loss Pinvsw is a value proportional to the switching frequency of the inverter 3, similar to the switching loss Pconsw described above. At the same torque output, the switching voltage of each switching element increases in response to the increase in the output voltage Vdc, so that the switching loss Pinvsw increases. The loss Pinvline due to the wiring impedance increases as the passing current of the inverter 3 (that is, the motor current Im) increases. Therefore, under the same torque output, the motor current Im decreases as the output voltage Vdc increases, so that the loss Pinvline decreases.

Therefore, for the power loss Pinv, the power loss Pinv with respect to the voltage command value Vdc * can be calculated by creating a map in advance with the switching frequency of the inverter 3 and the output voltage Vdc as parameters.

The power loss Pmot in the AC motor 4 is the sum of the copper loss generated by the current flowing in each phase coil winding and the iron loss generated by the change in the magnetic flux of the iron core portion. Under the same torque output, the copper loss decreases as the motor current Im decreases as the output voltage Vdc increases. The power loss Pmot can generally be estimated based on the operating state (rotational speed and torque) of the AC motor 4. For example, by obtaining the relationship between the operating state and output voltage Vdc of the AC motor 4 and the power loss in the AC motor 4, the power loss is based on the output request to the AC motor 4 and the voltage command value Vdc *. A map for estimating Pmot can be set.

In this way, the power loss calculation unit 20 uses at least one of the operating state of the AC motor 4, the output voltage Vdc, the battery voltage VB, the battery temperature TB, and the switching frequency in the boost converter 2 and the inverter 3 as parameters. , Power loss Pbat, Pcon, Inv, Motor can be estimated respectively.

For example, the power loss calculation unit 20 creates a map in advance with the battery temperature TB and the voltage difference | Vdc-VB | as parameters, and by referring to the map, the power loss Pbat at the voltage command value Vdc * can be obtained. calculate. Further, the power loss calculation unit 20 prepares in advance a map with the voltage difference | Vdc-VB | and the switching frequency of the boost converter 2 as parameters, and by referring to the map, the power at the voltage command value Vdc * Calculate the loss Pcon.

The power loss calculation unit 20 further creates a map in advance using the operating state of the AC motor 4, the output voltage Vdc, and the switching frequency of the inverter 3 as parameters, and by referring to the map, the voltage command value Vdc * The power loss Pinv in is calculated. Further, the power loss calculation unit 20 creates a map in advance using the operating state of the AC motor 4 and the output voltage Vdc as parameters, and calculates the power loss Pmot at the voltage command value Vdc * by referring to the map. do.

When each of the power losses Pbat, Pcon, Pinv, and Pmot is calculated by the above-mentioned method, the power loss calculation unit 20 substitutes each calculated power loss into the equation (1) to obtain a power loss during boosting. Calculate Plus1.

[2] Calculation of non-boost power loss Plus 2 The power loss calculation unit 20 selects the non-boost operation to drive the AC motor 4, the power loss Pbat in the battery B, the power loss Pcon in the boost converter 2, and the inverter 3. The power loss Post 2 at the time of non-boost is calculated by summing the power loss Pinv in the power loss Pinv and the power loss Pmot in the AC motor 4. That is, the non-boost power loss Plus2 is expressed by the following equation.

Plus2 = Pbat + Pcon + Pinv + Pmot ... (2)
When the power loss calculation unit 20 sets the voltage command value Vdc * to the battery voltage VB (Vdc * = VB), the power loss calculation unit 20 uses the voltage command value Vdc * and the detection value of each sensor by the method shown below to obtain the power loss Pbat. , Pcon, Pinv, Pmot are calculated.

Since the battery current IB during non-boost operation is only the average current (DC component), the power loss Pbat in non-boost operation is indicated by the product of the internal resistance value Rbat and the square of the average current. Therefore, for the power loss Pbat, the power loss with respect to the voltage command value Vdc * (= VB) by creating a map in advance with the average current (direct current), that is, the operating state of the AC motor 4 and the battery temperature TB as parameters. Pbat can be calculated.

The power loss Pcon in the non-boost operation is represented by the loss Pconline due to the wiring impedance because the switching element Q7 is fixed off (Pcon = Pconline). This loss Pconline includes the conduction loss at the bypass switch 16. The power loss Pcon can also be calculated based on the average current of the battery B, that is, the operating state of the AC motor 4.

For the power loss Pinv and Pmot, the power loss Pinv and Pmot at the voltage command value Vdc * can be determined by referring to the map with the operating state of the AC motor 4 and the output voltage Vdc as parameters, as in the case of boosting power loss Plus1. Can be calculated.

When each of the power losses Pbat, Pcon, Pinv, and Pmot is calculated by the above-mentioned method, the power loss calculation unit 20 substitutes each calculated power loss into the equation (2) to obtain the non-boost power. Calculate the loss Plus2.

When the voltage command value generation unit 22 receives the boosted power loss Plus1 and the non-boosted power loss Plus2 calculated by the power loss calculation unit 20, the magnitude of these two power losses Plus1 and Plus2 is compared. When the boosted power loss Plus1 is smaller than the non-boosted power loss Plus2 (Ploss1 <Ploss2), the voltage command value generation unit 22 selects the boosting operation. In this case, the voltage command value generation unit 22 sets the voltage command value Vdc * to a voltage corresponding to the output request to the AC motor 4 and higher than the battery voltage VB.

On the other hand, when the non-boosting power loss Plus2 is smaller than the boosting power loss Plus1 (Ploss1> Pluss2), the voltage command value generation unit 22 selects the non-boosting operation. In this case, the voltage command value generation unit 22 sets the voltage command value Vdc * to the battery voltage VB.

That is, the voltage command value generation unit 22 sets the final voltage command value Vdc * based on the smaller voltage command value of the boosted power loss Plus1 and the non-boosted power loss Plus2. As a result, the voltage command value Vdc * is set so that the output voltage Vdc that minimizes the power loss of the entire vacuum cleaner 100 can be obtained.

The switching control unit 24 generates the control signals φs2 and φc of the boost converter 2 according to the voltage command value Vdc * set by the voltage command value generation unit 22. Specifically, when Vdc *> VB, the switching control unit 24 generates a control signal φc so that the output voltage Vdc becomes equal to the voltage command value Vdc *. The switching control unit 24 further generates a control signal φs2 for fixing the bypass switch off. In the boost converter 2, the duty ratio of the switching element Q7 is set in response to the control signal φc, and the boost ratio corresponds to the duty ratio.

On the other hand, when Vdc * = VB, the switching control unit 24 generates a control signal φc so as to fix the switching element Q7 off. The switching control unit 24 further generates a control signal φs2 for fixing the bypass switch on. The boost converter 2 supplies the battery voltage VB to the inverter 3 via the bypass switch and the diode.

The switching control unit 24 further generates a control signal φi of the inverter 3 according to the voltage command value Vdc *. By switching control of the inverter 3 according to the control signal φi, an AC voltage for outputting torque according to the output request is applied to the AC motor 4.

FIG. 5 is a flowchart illustrating control of the boost converter 2 in the vacuum cleaner 100 according to the first embodiment.

With reference to FIG. 5, the control device 5 sets an output request (rotational speed × torque) to the AC motor 4 in accordance with the required suction force specified by the operation command in step S01. In step S02, the control device 5 calculates the required motor voltage in accordance with the induced voltage of the AC motor 4 in accordance with the output request to the AC motor 4. The required voltage of the motor is set to be equal to or higher than the induced voltage of the AC motor 4.

Subsequently, the control device 5 sets the voltage command value Vdc * in the voltage range from the required motor voltage obtained in step S02 to the maximum output voltage of the boost converter 2 in step S03. The voltage command value Vdc * is set higher than the battery voltage VB (Vdc *> VB). In step S03, the voltage command value Vdc * for boosting operation is set.

Next, the control device 5 determines in step S04 whether or not the required motor voltage obtained in step S02 is equal to or less than the battery voltage VB. When the required motor voltage is higher than the battery voltage VB (when NO is determined in S04), the process proceeds to step S08, and boosting operation is selected. This is because if the required voltage of the motor is higher than the battery voltage VB, voltage saturation will occur when the AC motor 4 is driven in the state of the output voltage Vdc = VB.

On the other hand, when the required voltage of the motor is equal to or higher than the battery voltage VB (when YES is determined in S04), the control device 5 determines the power loss in the electric vacuum cleaner 100 at the voltage command value Vdc * set in step S03 by step S05. That is, the boosted power loss Voltage 1 is calculated. In step S05, the control device 5 has a power loss Pbat in the battery B at the voltage command value Vdc *, a power loss Pcon in the boost converter 2 at the voltage command value Vdc *, and a power loss at the inverter 3 at the voltage command value Vdc *. The power loss Pmot in the AC electric motor 4 at the Pinv and the voltage command value Vdc * is calculated. Then, the control device 5 calculates the boosted power loss Plus1 by summing the calculated power losses Pbat, Pcon, Pinv, and Pmot.

Subsequently, in step S06, the control device 5 calculates the power loss in the vacuum cleaner 100 at the voltage command value Vdc * = VB, that is, the power loss during non-boost, Ploss 2. In step S05, the control device 5 calculates the power loss Pbat in the battery B at Vdc * = VB, the power loss Pcon in the boost converter 2, the power loss Pinv in the inverter 3, and the power loss Pmot in the AC motor 4. do. Then, the control device 5 calculates the non-boost power loss Ploss 2 by summing the calculated power losses Pbat, Pcon, Pinv, and Pmot.

The control device 5 compares the boosted power loss Plus1 calculated in step S05 with the non-boosted power loss Plus2 calculated in step S06 in step S07. When the boosted power loss Plus1 is smaller than the non-boosted power loss Plus2 (when YES is determined in step S07), the control device 5 proceeds to step S08 and selects boosting operation. The control device 5 sets the voltage command value Vdc * used for driving the AC motor 4 to the voltage command value Vdc * set in step S03.

On the other hand, when the boosted power loss Plus1 is equal to or greater than the non-boosted power loss Plus2 (NO determination in S07), the control device 5 proceeds to step S09 and selects the non-boost operation. The control device 5 sets the voltage command value Vdc * used for driving the AC motor 4 to the battery voltage VB.

Subsequently, the control device 5 proceeds to step S10 and generates the control signals φs2 and φc of the boost converter 2 and the control signal φi of the inverter 3 according to the voltage command value Vdc * set in step S08 or S09. The boost converter 2 supplies the voltage Vdc according to the voltage command value Vdc * to the inverter 3 by the on / off operation of the switching element Q7 in response to the control signal φc. The inverter 3 drives the AC motor 4 according to the required output by the on / off operation of the switching elements Q1 to Q6 in response to the control signal φi.

As described above, according to the electric vacuum cleaner according to the first embodiment, when the required suction force is generated in the electric blower, the electric vacuum cleaner as a whole is based on the estimation of the boosted power loss and the non-boosted power loss. Boosting and non-boosting operations can be selectively performed so that the power loss of the power loss is small. As a result, the efficiency of the entire vacuum cleaner can be improved. As a result, in the vacuum cleaner, the continuous use time per charge can be lengthened.

Embodiment 2.
In the second embodiment, the control of the boosting rate during the boosting operation in the vacuum cleaner 100 according to the first embodiment will be described. Therefore, detailed description of the configuration of the vacuum cleaner 100 (FIGS. 1 to 3) and common parts with the first embodiment such as selection of step-up operation and non-boost-up operation in the control device 5 will not be repeated.

FIG. 6 is a diagram illustrating control of the boosting rate during the boosting operation. FIG. 6 shows the relationship between each of the output voltage Vdc, the battery voltage VB, and the boost rate (Vdc / VB) of the boost converter 2 and the remaining capacity (battery capacity) of the battery B. The relationship shown in FIG. 6 is based on the discharge characteristics when the battery B is a lithium ion battery.

With reference to FIG. 6, during the boosting operation, the voltage command value Vdc * is set in response to the output request (rotational speed × torque) to the AC motor 4 according to the required suction force. It is assumed that the voltage command value Vdc * is set to a voltage V1 higher than the battery voltage VB (V1> VB). The control device 5 generates a control signal φc so that the output voltage Vdc of the boost converter 2 becomes equal to the voltage command value Vdc * based on the voltage command value Vdc * and the detection values of the voltage sensors 7 and 8.

The boost converter 2 supplies the voltage Vdc obtained by boosting the voltage VB supplied from the battery B to the inverter 3. During the boosting operation, the battery voltage VB changes depending on the battery capacity. On the horizontal axis of FIG. 6, MAX indicates an upper limit value of a preset battery capacity management range, and MIN indicates a lower limit value of the management range. When the battery capacity is the upper limit value MAX, the battery voltage VB indicates the maximum value VB1. When the battery capacity decreases from the upper limit value MAX, the battery voltage VB also decreases from the maximum value VB1. When the battery capacity is the threshold value Th, the battery voltage VB = VB2. When the battery capacity falls below the threshold Th, the battery voltage VB becomes even lower than VB2.

The rate of decrease in the battery voltage VB with respect to the battery capacity becomes higher when the battery capacity is lower than the threshold value Th, as compared with the case where the battery capacity is larger than the threshold value Th. The rate of decrease in the battery voltage VB with respect to the battery capacity indicates the amount of decrease in the battery voltage VB per unit capacity.

Using the rate of decrease in battery voltage VB with respect to this battery capacity, the rate of change over time in battery voltage VB when boosting operation is performed while keeping the battery current IB (discharge current) constant, that is, the battery voltage VB within a unit time. Focusing on the amount of change in the battery voltage, it is understood that when the battery capacity falls below the threshold Th, the rate of change in the battery voltage VB over time increases.

Here, consider a case where the boosting rate is fixed to a constant value and the boosting operation is executed. In FIG. 6, as shown by the broken line, the boost rate is fixed to V1 / VB1 based on the battery voltage VB1 when the battery capacity is the upper limit value MAX and the voltage command value Vdc * = V1.

When the boost rate is constant (= V1 / VB1), when the battery voltage VB decreases as the battery capacity decreases, the output voltage Vdc of the boost converter 2 also decreases. As a result, as shown by the broken line in FIG. 6, the output voltage Vdc becomes a voltage lower than V1 which is the voltage command value Vdc *. Therefore, as the battery capacity decreases, the output of the AC motor 4 does not meet the output requirement, and as a result, the suction force generated by the electric blower 106 also decreases.

As described above, when the boosting operation is executed with the boosting rate fixed at a constant value, there arises a problem that the suction power of the vacuum cleaner 100 decreases as the battery capacity of the battery B decreases. As a result, the user may be dissatisfied with the unintended decrease in suction power.

Therefore, in the vacuum cleaner according to the second embodiment, the boost rate is changed according to the battery capacity so that the output voltage Vdc is constant with respect to the battery capacity. Specifically, as shown by the solid line in FIG. 6, when the voltage command value Vdc * = V1 is set, the boost rate is set higher as the battery capacity decreases. According to this, the boost rate (= V1 / VB2) when the battery capacity is the threshold value Th is set higher than the boost rate (= V1 / VB1) when the battery capacity is the upper limit value MAX.

By doing so, the output voltage Vdc can be maintained at V1, which is the voltage command value Vdc *, within the range of the battery capacity from the upper limit value MAX to the threshold value Th. Therefore, even if the battery capacity decreases, the output of the AC motor 4 satisfies the output requirement, and as a result, the suction power of the vacuum cleaner 100 can be maintained.

However, when the battery capacity is lower than the threshold value Th, the rate of decrease of the battery voltage VB with respect to the battery capacity becomes high. Therefore, in order to keep the output voltage Vdc at V1, the boost rate is further increased, and the discharge current of the battery B is increased. This may result in over-discharging of the battery B. Further, if the battery B is continuously used in this state, the output voltage Vdc may become unstable, and as a result, the rotation speed of the AC motor 4 may fluctuate. Further, the over-discharge of the battery B causes the output voltage Vdc to drop sharply, which may cause the vacuum cleaner 100 to malfunction.

Therefore, when the battery capacity falls below the threshold value Th during the execution of the boost rate control described above, the control device 5 stops the boost operation. Specifically, the control device 5 fixes the switching element Q7 to off. At this time, the control device 5 may turn off the switching element Q7 and turn on the bypass switch. Therefore, when the battery capacity is lower than the threshold value Th, the boost rate is 1, and the output voltage Vdc is equal to the battery voltage VB.

The control device 5 further stops the operation of the inverter 3. By stopping the drive of the AC motor 4, the discharge of the battery B is stopped. This makes it possible to prevent the battery B from being over-discharged.

FIG. 7 is a functional block diagram illustrating a control configuration relating to control of the boost converter 2 in the vacuum cleaner 100 according to the second embodiment. The control device 5 in the vacuum cleaner 100 according to the second embodiment is obtained by adding the battery capacity estimation unit 26 to the control device 5 shown in FIG.

The battery capacity estimation unit 26 estimates the battery capacity of the battery B based on the battery voltage VB detected by the voltage sensor 7. Specifically, the battery capacity estimation unit 26 estimates the battery capacity based on the magnitude of the battery voltage VB and / or the temporal change rate of the battery capacity. Specifically, the battery capacity estimation unit 26 estimates the battery capacity from the detected value of the voltage sensor 7 by using a map or a mathematical formula showing the relationship between the battery voltage VB and the battery capacity as shown in FIG.

The voltage command value generation unit 22 sets the voltage command value Vdc * in response to the output request to the AC motor 4 during the boosting operation. The switching control unit 24 changes the boost rate according to the battery capacity estimated by the battery capacity estimation unit 26 with respect to the set voltage command value Vdc *. Specifically, since the battery voltage VB decreases as the battery capacity decreases (see FIG. 6), the voltage command value generation unit 22 increases the boost rate in response to the decrease in the battery capacity. As a result, under the same voltage command value Vdc *, the boost rate when the detected value VB of the voltage sensor 7 is the first value is higher than the first value of the detected value VB of the voltage sensor 7. It is higher than the boost rate at the second value.

As a result, the boost converter 2 can continue to supply the voltage Vdc corresponding to the voltage command value Vdc * to the inverter 3 regardless of the decrease in the battery capacity. Therefore, since the output shortage of the AC motor 4 is suppressed, the electric blower 106 can generate a suction force according to the required suction force.

Further, when the battery capacity estimated by the battery capacity estimation unit 26 falls below the threshold value Th, the switching control unit 24 stops the boosting operation and stops the operation of the inverter 3 to prevent the battery B from being over-discharged. ..

When the boosting operation and the operation of the inverter 3 are stopped in order to prevent the battery B from overheating, the control device 5 causes the display unit 14 to indicate to that effect. This prevents the user from feeling that the operation of the vacuum cleaner 100 has stopped unexpectedly.

FIG. 8 is a flowchart illustrating the boosting rate control in the vacuum cleaner 100 according to the second embodiment.

With reference to FIG. 8, the control device 5 determines in step S11 whether or not the boosting operation is selected in the boosting converter 2. When the boosting operation is not selected, that is, when the non-boosting operation is selected (NO determination in S11), the control device 5 skips the subsequent processing.

On the other hand, when boosting operation is selected (when YES is determined in S11), the control device 5 receives the detected value of the battery voltage VB from the voltage sensor 7 in step S12. Then, the control device 5 estimates the battery capacity of the battery B based on the detected value of the battery voltage VB in step S13.

The control device 5 subsequently determines in step S14 whether or not the battery capacity is equal to or greater than the threshold value Th. When the battery capacity is equal to or higher than the threshold value Th (when YES is determined in S14), the control device 5 proceeds to step S15 and sets the voltage command value Vdc * in response to the output request to the AC motor 4.

Next, in step S16, the control device 5 generates the control signals φs2 and φc of the boost converter 2 and the control signal φi of the inverter 3 according to the voltage command value Vdc * set in step S15. At this time, the control device 5 generates a control signal φc so that the boost rate increases in response to the decrease in battery capacity.

The boost converter 2 supplies the voltage Vdc according to the voltage command value Vdc * to the inverter 3 by the on / off operation of the switching element Q7 in response to the control signal φc. The inverter 3 drives the AC motor 4 according to the required output by the on / off operation of the switching elements Q1 to Q6 in response to the control signal φi.

On the other hand, when the battery capacity is smaller than the threshold value Th (at the time of NO determination in S14), the control device 5 stops the boosting operation in step S17 and stops the operation of the inverter 3 in step S18.

As described above, according to the electric vacuum cleaner according to the second embodiment, during the step-up operation, the voltage is boosted when the battery voltage VB is the first value with respect to the voltage command value set based on the required suction force. The rate is made higher than the boost rate when the battery voltage VB is a second value higher than the first value. In this way, the boost converter 2 can continue to supply the voltage Vdc corresponding to the voltage command value to the inverter 3 regardless of the decrease in the battery capacity. As a result, the AC motor 4 is driven according to the output request, so that the suction power of the vacuum cleaner can be maintained. Therefore, it is possible to eliminate the user's dissatisfaction due to an unintended decrease in suction power.

Further, since the output voltage Vdc of the boost converter 2 can be kept within a predetermined range by the boost rate control, the inverter 3 and the AC motor 4 may be designed based on the applied voltage corresponding to the predetermined range. .. For example, even when a reactor having a large current dependence of the characteristic value is used, the characteristic value can be set to the optimum value in the predetermined voltage range, so that the efficiency of the vacuum cleaner can be improved.

Further, under the same output of the AC motor 4, the output voltage Vdc is higher than that in the case where the boost rate is lowered according to the decrease in the battery capacity, so that the power loss in the inverter 3 and the AC motor 4 is small. can do.

Embodiment 3.
The discharge characteristics of a secondary battery typically used as the battery B deteriorate as the battery temperature decreases. Therefore, if the vacuum cleaner 100 is started when the battery temperature is low, the output of the AC motor 4 may be insufficient and a suction force equal to the required suction force may not be generated.

Therefore, when the battery temperature is low, it is necessary to raise the temperature of the battery B promptly when the vacuum cleaner 100 is started. In the third embodiment, a temperature raising operation for raising the temperature of the battery B will be described. The details of the configuration of the vacuum cleaner 100 (FIGS. 1 and 2) and the common parts with the first embodiment such as selection of step-up operation and non-boost-up operation in the control device 5 will not be repeated.

FIG. 9 is a functional block diagram illustrating a control configuration relating to control of the boost converter 2 in the vacuum cleaner 100 according to the third embodiment. The control device 5 in the vacuum cleaner 100 according to the third embodiment is obtained by adding a battery capacity estimation unit 26 and a temperature rise control unit 28 to the control device 5 shown in FIG.

When the operation switch for starting the suction cleaning is operated in the operation unit 13 (FIG. 1), the temperature rise control unit 28 raises the temperature of the battery B based on the battery temperature TB detected by the temperature sensor 12. It is determined whether or not to carry out the temperature raising operation for the purpose. Specifically, the temperature rise control unit 28 determines that the temperature rise operation is performed when the battery temperature TB is lower than a predetermined lower limit (lower limit temperature TBL in FIG. 10). The temperature rise control unit 28 instructs the voltage command value generation unit 22 to perform the temperature rise operation.

Upon receiving an instruction from the temperature rise control unit 28, the voltage command value generation unit 22 performs a temperature rise operation so that the battery voltage TB becomes equal to or higher than the lower limit temperature TBL. FIG. 10 is a diagram for explaining a temperature raising operation executed by the control device 5. FIG. 10 shows changes in the output voltage Vdc and the battery temperature TB of the boost converter 2 after the timing when the operation switch for starting the suction cleaning is turned on.

With reference to FIG. 10, when the battery temperature TB is lower than the lower limit temperature TBL at the time t1 when the operation switch is turned on, the temperature raising operation is started. In the temperature rise operation, the boost converter 2 is controlled to execute the boost operation.

Specifically, the voltage command value generation unit 22 (FIG. 9) sets the voltage command value Vdc * to a predetermined voltage V2 higher than the battery voltage VB. Assuming that the voltage command value Vdc * set based on the output request to the AC motor 4 is the voltage V1, the voltage V2 is set lower than the voltage V1. That is, the voltage command value Vdc * for the temperature rise operation is set lower than the voltage command value Vdc * for the normal operation.

The switching control unit 24 generates control signals φs2 and φc for controlling the boost converter 2 according to the voltage command value Vdc * set by the voltage command value generation unit 22. The switching control unit 24 generates a control signal φc so that the output voltage Vdc becomes equal to the voltage command value Vdc *. The switching control unit 24 further generates a control signal φs2 for fixing the bypass switch 16 (FIG. 3) off. In the boost converter 2, the duty ratio of the switching element Q7 is set in response to the control signal φc, and the boost ratio corresponds to the duty ratio.

When the boost converter 2 executes the boost operation, a ripple current (alternating current component) is generated in the battery B. The ripple current increases according to the voltage difference | Vdc-VB | between the output voltage Vdc and the battery voltage VB. When the ripple current is generated, the internal resistance of the battery B generates heat, so that the temperature of the battery B rises. That is, in the temperature raising operation, the battery B is heated from the inside by executing the boosting operation.

Therefore, if the ripple current is increased, that is, if the voltage difference | Vdc-VB | is increased, the temperature of the battery B can be effectively raised. However, in a secondary battery represented by a lithium ion battery or a nickel hydrogen battery, the internal resistance value generally increases as the temperature decreases. Therefore, if the ripple current is increased, the voltage generated in the internal resistance becomes large, and the voltage of the secondary battery may exceed the upper limit voltage permitted in terms of safety and durability. Therefore, during the temperature rise operation, the voltage command value Vdc * is set so that the ripple current becomes maximum within the range where the voltage of the battery B does not exceed the upper limit voltage. As a result, the temperature of the battery B can be raised without imposing a burden on the battery B. However, since the output voltage Vdc during the temperature rise operation is lower than the voltage V1 that should be originally output, the output of the AC motor 4 is limited.

When the battery B is heated by the temperature raising operation and the battery temperature TB becomes equal to or higher than the lower limit temperature TBL (time t3), the control device 5 ends the temperature raising operation and shifts the vacuum cleaner 100 to the normal operation. In normal operation, the boost converter 2 supplies the voltage Vdc (= V1) according to the voltage command value Vdc * to the inverter 3. The inverter 3 drives the AC motor 4 according to the required output.

Further, when the battery temperature TB rises during the execution of the normal operation and reaches a predetermined upper limit (upper limit temperature TBH in FIG. 10) (time t4), the control device 5 stops the boosting operation and operates the inverter 3. To stop. This prevents the battery B from overheating.

FIG. 11 is a flowchart illustrating a temperature raising operation executed in the vacuum cleaner 100 according to the third embodiment.

With reference to FIG. 11, the control device 5 determines in step S21 whether or not the operation switch for starting the suction cleaning is turned on by the operation unit 13. When it is determined that the operation switch is not turned on (NO determination in S21), the control device 5 skips the subsequent processing.

On the other hand, when it is determined that the operation switch is turned on (when YES is determined in S21), the control device 5 receives the detected value of the battery temperature TB from the temperature sensor 12 in step S22. The control device 5 determines in step S23 whether or not the battery temperature TB is lower than the predetermined lower limit temperature TBL. When the battery temperature TB is lower than the lower limit temperature TBL (when YES is determined in S23), the control device 5 proceeds to step S24 and executes the temperature raising operation. The control device 5 raises the temperature of the battery B by causing the boost converter 2 to perform a boosting operation.

On the other hand, when the battery temperature TB is equal to or higher than the lower limit temperature TBL (at the time of NO determination in S23), the control device 5 proceeds to step S25 and executes normal operation. The control device 5 controls the boost converter 2 according to the voltage command value Vdc * corresponding to the required output to the AC motor 4.

The control device 5 determines in step S26 whether or not the battery temperature TB is higher than the predetermined upper limit temperature TBH. When the battery temperature TB is equal to or lower than the upper limit temperature TBH (at the time of NO determination in S26), the control device 5 skips the subsequent processing.

On the other hand, when the battery temperature TB is higher than the upper limit temperature TBH (when YES determination in S26), the control device 5 proceeds to step S27 and stops the boosting operation. The control device 5 further stops the operation of the inverter 3 by step S28.

During the temperature rise operation, the boost converter 2 supplies the inverter 3 with a voltage V2 lower than the voltage V1 corresponding to the output request to the AC motor 4. Therefore, the suction force may be lowered due to insufficient output of the AC motor 4, which may give the user a sense of discomfort. Therefore, the control device 5 causes the display unit 14 (FIG. 1) to indicate that the temperature rising operation is being executed, so that the decrease in the suction force is temporary until the battery B heats up. Notify the user of this. This makes it possible to prevent a feeling of strangeness given to the user.

Further, the control device 5 causes the display unit 14 to display to that effect even when the boosting operation and the operation of the inverter 3 are stopped in order to prevent the battery B from overheating. This makes it possible to prevent the user from feeling that the operation of the vacuum cleaner 100 has stopped unexpectedly.

In the above embodiment, an electric vacuum cleaner provided with an AC motor that receives power from a power storage device to drive an electric blower has been described, but the present invention is not limited to the electric vacuum cleaner, but the power storage device. It can be widely applied to products whose drive source is an AC motor driven by stored electric power. For example, the present invention can be applied to a product provided with an electric blower such as a hand dryer.

It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and is intended to include all modifications within the meaning and scope of the claims.

2 Boost converter, 3 Inverter, 4 AC motor, 5 Controller, 6 Power switch, 7,8,9 Voltage sensor, 10,11 Current sensor, 12 Temperature sensor, 13 Operation unit, 14 Display unit, 15 Rotation angle sensor, 16 Bypass switch, 20 Power loss calculation unit, 22 Voltage command value generation unit, 24 Switching control unit, 26 Battery capacity estimation unit, 28 Temperature rise control unit, 100 Electric vacuum cleaner, 102 Handle, 104 Power supply unit, 106 Electric blower , 108 Dust collection chamber, 110 housing, 112 suction part, 113 ventilation path, 114 suction port, 116 board, B battery, L1 reactor, C1 capacitor, Q1 to Q7 switching element, D1 to D8 diode.

Claims (9)

AC motors configured to drive electric blowers and
Power storage device and
A boost converter configured to boost the DC voltage received from the power storage device, and
An inverter that converts the output voltage of the boost converter into an AC voltage for driving the AC motor, and
It comprises a boost converter and a control device configured to control the inverter.
The boost converter selectively executes a boosting operation in which the boosting rate indicated by the ratio of the output voltage to the voltage of the power storage device is higher than 1, and a non-boosting operation in which the boosting rate is fixed at 1. Consists of
A vacuum cleaner that increases the boosting rate in response to a decrease in the remaining capacity of the power storage device so that the output voltage becomes constant with respect to the remaining capacity of the power storage device during the boosting operation. Further equipped with a voltage sensor for detecting the voltage of the power storage device,
During the boosting operation, the control device detects the boosting rate when the detection value of the voltage sensor is the first value with respect to the voltage command value set based on the required suction force. The electric vacuum cleaner according to claim 1, wherein the value is higher than the boosting rate when the value is higher than the first value and the second value is higher than the first value. The control device estimates the remaining capacity of the power storage device based on the detection value of the voltage sensor during the boosting operation.
The vacuum cleaner according to claim 2, wherein when the remaining capacity drops below a predetermined threshold value, the boosting operation is stopped and the operation of the inverter is stopped. In the case of generating the required suction force in the electric blower,
The first power loss that occurs in the electric vacuum cleaner when the boosting operation is selected and the AC motor is driven, and the first power loss that occurs in the electric vacuum cleaner when the non-boosting operation is selected and the AC motor is driven. Calculate the second power loss and
When the first power loss is greater than the second power loss, the boost converter and the inverter are controlled to perform the non-boost operation to drive the AC motor, while controlling the boost converter and the inverter.
Claims 1 to 3, wherein when the first power loss is smaller than the second power loss, the step-up converter and the inverter are controlled so as to execute the step-up operation to drive the AC motor. The electric vacuum cleaner according to any one of the items. The control device is
By summing up the power loss in the power storage device, the power loss in the boost converter, the power loss in the inverter, and the power loss in the AC motor when the boosting operation is selected and the AC motor is driven, the first step is performed. Calculate the power loss of 1 and
The power loss in the power storage device, the power loss in the boost converter, the power loss in the inverter, and the power loss in the AC motor when the non-boosting operation is selected and the AC motor is driven are summed up. The electric cleaner according to claim 4, wherein the second power loss is calculated. The boost converter
A step-up chopper circuit with a reactor and a switching element,
Including a bypass switch electrically connected in parallel to the reactor.
The vacuum cleaner according to any one of claims 1 to 5, wherein the control device supplies the voltage of the power storage device to the inverter by turning on the bypass switch when the non-boost operation is selected. .. Further equipped with a temperature sensor for detecting the temperature of the power storage device,
The control device is
When the detection value of the temperature sensor is lower than a predetermined lower limit value at the time of starting the vacuum cleaner, a temperature raising operation for raising the temperature of the power storage device by the boosting operation is executed.
When the detection value of the temperature sensor exceeds the predetermined lower limit value during the execution of the temperature rise operation, the temperature rise operation is terminated and the boost converter and the inverter are used so that the electric blower generates the required suction force. The electric vacuum cleaner according to claim 1. The control device is configured to control the output voltage of the boost converter according to the voltage command value during the boost operation.
The vacuum cleaner according to claim 7, wherein the voltage command value during the temperature rise operation is set to be lower than the voltage command value set based on the required suction force. 7. The vacuum cleaner described in.

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