JP5890215B2 - Power converter for pump drive - Google Patents

Description

  The present invention relates to an operation of a power conversion apparatus when a power conversion apparatus is activated by an induced voltage generated by the synchronous motor in a pump system driven by the synchronous motor in a state where power is not supplied from a commercial power source.

  Permanent magnet synchronous motors are widely used in various fields because they are highly efficient and maintenance-free. Since this permanent magnet synchronous motor uses a permanent magnet for the rotor, when it rotates freely by inertia or external energy, a voltage induced by the rotation of the permanent magnet appears at the motor terminal.

  In this specification, a state in which the motor is rotated by external kinetic energy or inertia without being supplied with electric power is referred to as “free rotation”. In a situation where the motor rotates freely, for example, when the motor is used to drive a pump, the impeller may rotate as a water wheel by the liquid flowing in the pump. In such a situation, the voltage output from the motor terminal depends on the rotational speed of the motor.

  The free rotation of the motor can occur even when power is not supplied from a commercial power source, that is, a power source on the primary side of the power converter. Therefore, a voltage appearing at the motor terminal in a situation where electric power is not supplied from the commercial power supply may be applied to the power conversion device to start the power conversion device.

  When the power converter starts up with the voltage applied from the motor, even if the power converter can be operated in synchronization with the rotation of the motor, the power supply to the power converter is unstable and the motor is controlled. It cannot be maintained.

Japanese Patent Laid-Open No. 3-155393 JP-A-5-83965 Japanese Patent Laid-Open No. 2001-50168 JP 2005-137106 A

  In a system in which two or more pumps are installed in series, such as a circulatory system, the power conversion device is likely to be activated by the induced voltage of the motor as described above. For example, in the system shown in FIG. 1, two pumps, a pump P0 driven as a main pump and a pump P1 driven by a timely command, are installed in series. The power converter 5 shown in FIG. 1 is used to drive a motor M1 connected to the pump P1. In this system, for example, when a breaker such as MCB (small circuit breaker) or ELB (leakage breaker) indicated by SW is cut off, power is not supplied to the power converter 5, so the power converter 5 does not start. . However, there is a case where the pump P1 rotates freely by the operation of the pump P0, and the power converter 5 is activated by the induced voltage of the motor M1 connected thereto.

  When the power conversion device 5 is activated by the voltage induced by the motor M1 connected to the freely rotating pump P1, the MCU (microcomputer unit or micro control unit) built in the power conversion device 5 is activated. Then, the LED of the display operation unit, the 7-segment display, etc. are lit. For this reason, the user may recognize that the power conversion device 5 has received power from the commercial power source 1 and started up. In order to determine whether the power converter 5 is activated by receiving power from the commercial power source 1 or receiving power generated by the motor M1, the user, for example, It is necessary to check whether or not a live line is present using a measuring instrument, which is a difficult task.

  Further, when the power conversion device 5 is activated by the voltage induced by the motor M1, the pump P1 cannot be driven because the power source is unstable even if an operation command is given to the power conversion device 5, and the pump P1 is driven. It becomes difficult to investigate the cause that cannot be done.

  The present invention has been made to solve the above-described conventional problems, and informs the user that the power converter has been started by the voltage induced by the freely rotating motor and protects the power converter. An object of the present invention is to provide a power conversion device capable of performing the above.

One aspect of the present invention for achieving the above-described object is a power conversion device for driving a motor, which includes an inverter that supplies variable-frequency power to the motor, and a control that controls output power of the inverter. And a display unit that displays the state of the power converter, the inverter includes a control power source that generates control power for driving the power converter, and the control unit is the motor. based on the size or the commercial power supply of the generated induced voltage to the magnitude of the input voltage supplied to the inverter, it has a function of the power converter to determine whether activated by induced voltage of the motor The power converter further includes an input voltage measuring device that measures the input voltage supplied from the commercial power source to the inverter, and the controller The unit compares the measured input voltage with a preset starting voltage at which the control power supply is started, and when the input voltage is equal to or lower than the starting voltage, the power conversion device uses the induced voltage of the motor. Is displayed on the display unit, and the inverter is protected by prohibiting operation of the power converter .

A preferred aspect of the present invention is a power conversion device for driving a motor, the inverter supplying variable frequency power to the motor, a control unit for controlling the output power of the inverter, and the power conversion device. A display unit for displaying a state, wherein the inverter has a control power source for generating control power for driving the power converter, and the control unit is configured to generate an induced voltage generated by the motor or Based on the magnitude of the input voltage supplied to the inverter from a commercial power supply, the power converter has a function of determining whether or not it is activated by the induced voltage of the motor, the power converter, An induced voltage measuring device that measures the induced voltage generated by the motor, and a DC voltage that measures the DC voltage smoothed by the DC voltage smoothing unit of the inverter. A measuring device, and the control unit compares the measured induced voltage and the DC voltage, and when the induced voltage and the DC voltage are in a predetermined relationship, The fact that the power converter is activated is displayed on the display unit, and the inverter is protected by prohibiting operation of the power converter.
In a preferred aspect of the present invention, when the DC voltage is equal to or lower than the induced voltage, the control unit displays on the display unit that the power converter is activated by the induced power of the motor. Features.

A preferred aspect of the present invention is a power conversion device for driving a motor, the inverter supplying variable frequency power to the motor, a control unit for controlling the output power of the inverter, and the power conversion device. A display unit for displaying a state, wherein the inverter has a control power source for generating control power for driving the power converter, and the control unit is configured to generate an induced voltage generated by the motor or Based on the magnitude of the input voltage supplied to the inverter from a commercial power supply, the power converter has a function of determining whether or not it is activated by the induced voltage of the motor, the power converter, A frequency detector for detecting the angular frequency of the motor, and a DC voltage measuring device for measuring the DC voltage smoothed by the DC voltage smoothing unit of the inverter; The control unit further calculates an estimated value of the induced voltage generated by the motor from the angular frequency and the secondary linkage flux of the motor, compares the estimated value of the induced voltage and the DC voltage, When the estimated value of the induced voltage and the DC voltage have a predetermined relationship, the fact that the power converter is activated by the induced power of the motor is displayed on the display unit, and the operation of the power converter is performed. And the inverter is protected.
In a preferred aspect of the present invention, when the DC voltage is equal to or less than the estimated value of the induced voltage, the control unit displays on the display unit that the power converter is activated by the induced power of the motor. It is characterized by doing.

  According to the present invention, the power generated by the freely rotating motor can be received and the power conversion device can be displayed on the display unit, so that the power conversion device is activated, The user can be informed that the power supply from the commercial power source is cut off. Further, the inverter can be protected by setting the power conversion device in such a state to not accept the start command signal.

It is a figure which shows a circulatory system pump system. It is a block diagram which shows the power converter device which concerns on the 1st Embodiment of this invention. It is a figure which shows the equivalent circuit of a synchronous motor. It is a flowchart which shows the starting flow which concerns on the 1st Embodiment of this invention. It is a block diagram which shows the power converter device which concerns on the 2nd Embodiment of this invention. It is a flowchart which shows the starting flow which concerns on the 2nd Embodiment of this invention. It is a block diagram which shows the power converter device which concerns on the 3rd Embodiment of this invention. It is a flowchart which shows the starting flow which concerns on the 3rd Embodiment of this invention.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 2 is a block diagram illustrating a configuration of the power conversion device 5. This power converter 5 is used, for example, for driving a motor M1 connected to a pump P1 shown in FIG. As shown in FIG. 2, the power conversion device 5 includes an inverter 10, an MCU (control unit) 15, an input voltage measurement device 22, a DC voltage measurement device 23, and a display operation unit 19.

  The inverter 10 includes a converter circuit 11, an inverter circuit 12, a gate drive circuit 13, a DC voltage smoothing circuit 14, and a control power supply 18. The converter circuit 11 includes a rectifier circuit composed of diodes D11, D12, D13, D14, D15, and D16 so as to convert the three-phase AC power supplied from the commercial power source 1 into DC power. The DC voltage smoothing circuit 14 includes a capacitor C, and smoothes and stores the DC power converted by the converter circuit 11.

  The inverter circuit 12 has switching elements S1, S2, S3, S4, S5, and S6 such as IGBT (insulated gate bipolar transistor), and three-phase AC power from the DC power stored by the DC voltage smoothing circuit 14. Switching elements S1 to S6 and diodes D1 to D6 connected in parallel to the switching elements S1 to S6. The gate drive circuit 13 generates a gate drive signal for opening and closing each switching element of the inverter circuit. The switching element of the inverter circuit 103 is driven in accordance with a gate drive signal from the gate drive circuit 13. The control power supply 18 generates power for operating various devices of the power converter 5 from the DC power stored by the DC voltage smoothing circuit 14.

  The input voltage measuring device 22 measures the voltage input from the commercial power source 1 and sends the measured value to the MCU 15. The DC voltage measuring device 23 measures the voltage smoothed by the DC voltage smoothing circuit 14 and sends the measured value to the MCU 15.

  The display operation unit 19 is configured to receive a start command signal and a stop command signal from the outside of the power conversion device 5 and start and stop the power conversion device 5 based on these command signals. Furthermore, the display operation unit 19 is configured to be able to start and stop the operation of the power conversion device 5 by manual operation, and is configured to be able to input various set values. Further, the display operation unit 19 receives a frequency command signal from the outside of the power conversion device 5, outputs a signal indicating an operation state to the outside, and further displays the operation state of the power conversion device 5. The display operation unit 19 may be configured to connect to a higher-level control device via communication.

  The MCU 15 includes an AD conversion unit 17 and an inverter control unit 16. The AD converter 17 converts the analog voltage value input from the input voltage measuring device 22 and the DC voltage measuring device 23 into a digital value. The inverter control unit 16 controls the rotation speed of the permanent magnet synchronous motor M based on the frequency command signal sent from the display operation unit 16. That is, the MCU 15 receives the frequency command signal from the display operation unit 19 and generates a PWM signal. This PWM signal is sent to the gate drive circuit 13. The gate drive circuit 13 generates a gate drive signal for driving the switching element of the inverter circuit 12 based on the PWM signal. The switching element of the inverter circuit 12 is driven in accordance with a gate drive signal from the gate drive circuit 13, whereby the inverter 10 outputs AC power having a variable frequency.

  In the power converter 5 during normal operation, the AC power received from the commercial power source 1 is rectified by the converter circuit 11 and converted into DC power, and the DC voltage smoothing circuit 14 smoothes the voltage of the DC power. The control power supply 18 generates low-voltage DC power (control power) for driving the power converter 5 from the smoothed DC power.

  However, even when the power is not received from the commercial power source 1, the induced voltage generated by the free rotation of the motor M is converted to DC power by the D <b> 1 to D <b> 6 of the inverter circuit 12, and the DC power smoothed by the DC voltage smoothing circuit 14. Is generated. Therefore, even in this case, DC power is supplied to the control power supply 18 in the same manner as when receiving power from the commercial power supply 1, and the control power supply 18 can generate low-voltage DC power for driving the power converter 5.

  In the circulatory system pump system shown in FIG. 1, even when power is not supplied to the power converter 5 that drives the motor M1, the pump P1 rotates freely by the operation of the pump P0, and the induced voltage of the motor M1 connected thereto. As a result, the power conversion device 5 may be activated. Such free rotation of the pump can also occur in a so-called directly connected water supply apparatus in which the pump is directly connected to the water main. In a directly connected water supply device, water supply may be performed by the pressure of water from the water main even when the pump is stopped. Therefore, even when the motor M is not driven by the power converter 5, the pump impeller and the motor M connected thereto are rotated by the water flowing in the pump.

ここで、図２に示されるように、誘起電圧はインバータ回路１２によって整流されて直流電圧平滑回路１４に蓄えられるため、インバータ１０はコンデンサインプット型であり、入力インピーダンスは電解コンデンサのインピーダンスとなるためほぼ無限大と考えられる。よって、モータＭから電力変換装置５へ流れ込む電流はほぼ０［Ａ］と考えられる。よって、Iγ＝０［Ａ］、Iδ＝０［Ａ］となるので、式（１）は、

となる。モータＭが発生する電圧をＶ_Ｍとすると、電圧Ｖ_ＭはＶγとＶδのベクトル和から算出されるので、

したがって、モータＭが角速度ω[rad/sec]にて回転している場合、角速度ωとモータの２次鎖交磁束Ψの積から算出される電圧Ｖ_ＭがモータＭの端子から発生することがわかる。 The voltage induced by the rotation of the motor M is expressed as follows. FIG. 3 shows a general equivalent circuit of the synchronous motor. Equation (1) is derived from the equivalent circuit of FIG.

Here, as shown in FIG. 2, since the induced voltage is rectified by the inverter circuit 12 and stored in the DC voltage smoothing circuit 14, the inverter 10 is a capacitor input type, and the input impedance becomes the impedance of the electrolytic capacitor. It is almost infinite. Therefore, the current flowing from the motor M to the power conversion device 5 is considered to be approximately 0 [A]. Therefore, since Iγ = 0 [A] and Iδ = 0 [A], Equation (1) is

It becomes. When a voltage motor M occurs and V _M, since the voltage V _M is calculated from the vector sum of Vγ and V8,

Therefore, when the motor M is rotating at angular velocity ω [rad / sec], that voltage V _M is calculated from the product of 2 Tsugikusari flux linkage Ψ of the angular velocity omega and the motor is generated from the terminal of the motor M Recognize.

  In a state where the motor M is freely rotating, the control power source 18 of the inverter 10 may be activated by the induced voltage of the motor M even though power is not supplied from the commercial power source 1 to the inverter 10. When the control power supply 18 is activated, power is supplied from the control power supply 18 to the MCU 15, the display operation unit 19, and the like, and the entire power conversion device 5 is activated. Therefore, it is necessary to determine whether the control power source 18 has been established by supplying power from the commercial power source 1 or the motor M.

Hereinafter, an embodiment of a method for determining whether or not the control power supply 18 is activated by the induced voltage of the motor M (that is, whether or not the power conversion device 5 is activated by the induced voltage of the motor M) will be described with reference to the drawings. To do.
FIG. 4 shows a flowchart of the first embodiment. The MCU 15 executes a process of determining whether or not the power conversion device 5 has been activated using the induced voltage generated by the free rotation of the motor M as a power source.

  When the direct current voltage smoothed by the direct current voltage smoothing circuit 14 exceeds the activation voltage Vref of the control power supply 18, the control power supply 18 is activated and the MCU 15 is activated (step 1). After initial setting (step 2), the MCU 15 reads an analog voltage value measured by the input voltage measuring device 22, and the AD converter 17 of the MCU 15 converts the analog voltage value into a digital value Vin (step 3). ). Then, the MCU 15 compares the input voltage Vin obtained from the input voltage measuring device 22 with a preset starting voltage Vref that starts the control power supply 18 (step 4), and the input voltage Vin is equal to or lower than the starting voltage Vref. In this case (Vin ≦ Vref), it is determined that the power conversion device 5 is activated by the induced voltage of the freely rotating motor M. Further, the MCU 15 notifies the display operation unit 19 that the power supply from the commercial power source 1 is interrupted (step 5), and makes the display operation unit 19 not accepting the start command signal (step 6). The display operation unit 19 displays that the power converter 5 is activated by the induced voltage of the motor M. When the input voltage Vin is higher than the starting voltage Vref (Vin> Vref), the MCU 15 determines that the power converter 5 has been started upon receiving power supply from the commercial power source 1 (step 7).

Next, a second embodiment of the present invention will be described with reference to the drawings.
FIG. 5 shows a block diagram of the second embodiment, and FIG. 6 shows a flowchart of the second embodiment. As shown in FIG. 5, the power conversion device 5 of the second embodiment includes an inverter 10, an MCU 15, an induced voltage measurement device 24, a DC voltage measurement device 23, and a display operation unit 19. The internal configuration of the inverter 10 is the same as that in FIG. The second embodiment is different from the first embodiment in that the input voltage measuring device 22 is eliminated and an induced voltage measuring device 24 is added. However, an input voltage measuring device 22 may be provided. The induced voltage measuring device 24 measures the induced voltage generated by the motor M and sends the measured value to the MCU 15. The induced voltage measuring device 24 is also used as a voltage measuring device for measuring the voltage supplied from the inverter 10 to the motor M during normal operation.

  When the direct current voltage smoothed by the direct current voltage smoothing circuit 14 exceeds the activation voltage Vref of the control power supply 18, the control power supply 18 is activated and the MCU 15 is activated (step 1). After initial setting (step 2), the MCU 15 reads analog voltage values measured by the induced voltage measuring device 24 and the DC voltage measuring device 23, and the AD conversion unit 17 of the MCU 15 converts these analog voltage values into a digital value Vm. , Vdc (step 3). Then, the MCU 15 compares the induced voltage Vm obtained from the induced voltage measuring instrument 24 with the DC voltage Vdc obtained from the DC voltage measuring instrument 23 (step 4), and the DC voltage Vdc and the induced voltage Vm are determined in advance. When the DC voltage Vdc is equal to or lower than the induced voltage Vm (Vdc ≦ Vm), the power conversion device 5 determines that it is activated by the induced voltage of the motor M that freely rotates. . Further, the MCU 15 notifies the display operation unit 19 that the power supply from the commercial power source 1 is interrupted (step 5), and makes the display operation unit 19 not accepting the start command signal (step 6). The display operation unit 19 displays that the power converter 5 is activated by the induced voltage of the motor M. If the DC voltage Vdc is greater than the induced voltage Vm (Vdc> Vm), the MCU 15 determines that the power converter 5 has been activated upon receiving power supply from the commercial power source 1 (step 7).

Next, a third embodiment of the present invention will be described with reference to the drawings.
FIG. 7 is a block diagram of the third embodiment, and FIG. 8 is a flowchart of the third embodiment. As shown in FIG. 7, the power conversion device 5 of the third embodiment includes an inverter 10, an MCU 15, a frequency detector 25, a DC voltage measuring device 23, and a display operation unit 19. The internal configuration of the inverter 10 is the same as that in FIG. The third embodiment differs from the first embodiment and the second embodiment in that the input voltage measuring device 22 and the induced voltage measuring device 24 are eliminated, and the frequency detector 25 that detects the angular frequency ω of the motor M is provided. This is an added point.

  The frequency detector 25 calculates the angular frequency ω of the motor M from the induced voltage generated in the motor M. The obtained angular frequency ω is sent to the inverter control unit 16 of the MCU 15. In the present embodiment, the angular frequency ω of the motor M is used as a feedback signal related to the induced voltage. Since the frequency detector 25 outputs the angular frequency ω as a digital signal, the angular frequency ω can be directly sent to the inverter control unit 16 without going through the AD conversion unit 17. Therefore, this embodiment is advantageous when the MCU 15 having a small number of AD ports is used.

When the direct current voltage smoothed by the direct current voltage smoothing circuit 14 exceeds the activation voltage Vref of the control power supply 18, the control power supply 18 is activated and the MCU 15 is activated (step 1). After initial setting (step 2), the MCU 15 reads the angular frequency ω measured by the frequency detector 25 (step 3). In the above equation (3), if 2 Tsugikusari flux linkage Ψ of the motor M is known, it is possible to estimate the magnitude of the induced voltage V _M which the motor M is generated from the angular frequency ω of the motor M. Therefore, the MCU 15 calculates the induced voltage estimated value Vcal by multiplying the angular frequency ω and the secondary linkage magnetic flux Ψ (step 4).

  The MCU 15 reads the analog voltage value measured by the DC voltage measuring device 23, and the AD converter 17 of the MCU 15 converts this analog voltage value into a digital value Vdc (step 5). Then, the MCU 15 compares the calculated induced voltage estimated value Vcal and the DC voltage Vdc obtained from the DC voltage measuring instrument 23 (step 6), and the DC voltage Vdc and the induced voltage estimated value Vcal are determined in advance. Specifically, when the DC voltage Vdc is equal to or lower than the induced voltage estimated value Vcal (Vdc ≦ Vcal), it is determined that the power converter 5 is activated by the induced voltage of the motor M that freely rotates. . Further, the MCU 15 notifies the display operation unit 19 that the power supply from the commercial power source 1 is cut off (step 7), and makes the display operation unit 19 not accepting the start command signal (step 8). The display operation unit 19 displays that the power converter 5 is activated by the induced voltage of the motor M. When the DC voltage Vdc is larger than the induced voltage estimated value Vcal (Vdc> Vcal), the MCU 15 determines that the power converter 5 has been activated upon receiving power supply from the commercial power source 1 (step 9).

  As described above, the MCU 15 determines whether the power of the power conversion device 5 is the commercial power source 1 or the motor that freely rotates based on the detected or calculated magnitude of the induced voltage of the motor M or the magnitude of the input voltage from the commercial power. It can be determined from which of M the supply is being made.

  The embodiment described above is described for the purpose of enabling the person having ordinary knowledge in the technical field to which the present invention belongs to implement the present invention. Various modifications of the above embodiment can be naturally made by those skilled in the art, and the technical idea of the present invention can be applied to other embodiments. Accordingly, the present invention is not limited to the described embodiments, but is to be construed in the widest scope according to the technical idea defined by the claims.

DESCRIPTION OF SYMBOLS 1 Commercial power supply 5 Power converter 10 Inverter 11 Converter circuit 12 Inverter circuit 13 Gate drive part 14 DC voltage smoothing circuit 15 MCU
16 Inverter control unit 17 AD conversion unit 18 Control power supply 19 Display operation unit 22 Input voltage measuring device 23 DC voltage measuring device 24 Induced voltage measuring device 25 Frequency detector

Claims (5)

A power conversion device for driving a motor,
An inverter for supplying variable frequency power to the motor;
A control unit for controlling the output power of the inverter;
A display unit for displaying the state of the power converter,
The inverter has a control power source that generates control power for driving the power converter,
The control unit determines whether the power converter is activated by the induced voltage of the motor based on the magnitude of the induced voltage generated in the motor or the magnitude of the input voltage supplied from the commercial power source to the inverter. or have a function of determining,
The power conversion device further includes an input voltage measuring device that measures the input voltage supplied to the inverter from the commercial power source,
The control unit
Comparing the measured input voltage with a preset starting voltage at which the control power supply starts,
When the input voltage is less than or equal to the starting voltage, the display unit displays that the power converter is activated by the induced voltage of the motor,
A power conversion device for protecting the inverter by prohibiting operation of the power conversion device. A power conversion device for driving a motor,
An inverter for supplying variable frequency power to the motor;
A control unit for controlling the output power of the inverter;
A display unit for displaying the state of the power converter,
The inverter has a control power source that generates control power for driving the power converter,
The control unit determines whether the power converter is activated by the induced voltage of the motor based on the magnitude of the induced voltage generated in the motor or the magnitude of the input voltage supplied from the commercial power source to the inverter. Has a function to determine whether
The power conversion device further includes an induced voltage measuring device that measures an induced voltage generated by the motor, and a DC voltage measuring device that measures a DC voltage smoothed by a DC voltage smoothing unit of the inverter,
The control unit
Comparing the measured induced voltage with the DC voltage;
When the induced voltage and the DC voltage are in a predetermined relationship, the display unit displays that the power converter is activated by the induced power of the motor,
The power converter prohibited to be that power conversion device and performing protection of the inverter operation of the device. Said control unit, when the DC voltage is below the induced voltage, the effect that the power conversion device by inducing power of the motor is activated to claim 2, characterized in that displayed on the display unit The power converter described. A power conversion device for driving a motor,
An inverter for supplying variable frequency power to the motor;
A control unit for controlling the output power of the inverter;
A display unit for displaying the state of the power converter,
The inverter has a control power source that generates control power for driving the power converter,
The control unit determines whether the power converter is activated by the induced voltage of the motor based on the magnitude of the induced voltage generated in the motor or the magnitude of the input voltage supplied from the commercial power source to the inverter. Has a function to determine whether
The power converter further includes a frequency detector that detects an angular frequency of the motor, and a DC voltage measuring instrument that measures a DC voltage smoothed by a DC voltage smoothing unit of the inverter,
The control unit
Calculating an estimated value of the induced voltage generated by the motor from the angular frequency and the secondary linkage flux of the motor;
Compare the estimated value of the induced voltage and the DC voltage,
When the estimated value of the induced voltage and the direct current voltage are in a predetermined relationship, the display unit displays that the power converter is activated by the induced power of the motor,
The power converter prohibited to be that power conversion device and performing protection of the inverter operation of the device. The said control part displays on the said display part that the said power converter device is started by the induced electric power of the said motor, when the said DC voltage is below the estimated value of the said induced voltage. Item 5. The power conversion device according to Item 4 .

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