JP6965695B2 - Power supply - Google Patents

Description

The present invention relates to a power supply device, and more particularly to a power supply device including a boost converter that exchanges electric power with a voltage conversion between a power storage device and an electric load.

Conventionally, as a power supply device of this type, a device including a DC / DC converter that boosts power from a battery and supplies it to a drive circuit of a motor has been proposed (see, for example, Patent Document 1). In this device, the target voltage on the motor side is determined based on the power supplied to the motor, and the switching of the switching element of the DC / DC converter is duty-controlled so that the output voltage on the motor side approaches the target voltage.

JP-A-2010-252591

In the above-mentioned power supply device, if the current (boosting current) from the DC / DC converter becomes excessive, it may not be possible to extract power from the battery or the element may be damaged. Therefore, switching of the DC / DC converter Limitations are made to the switching duty of the element. Imposing a duty limit in this way reduces the responsiveness of the boosted current.

The main object of the power supply device of the present invention is to achieve both the extraction of electric power from the battery by the boost converter and the responsiveness of the boost current.

The power supply device of the present invention has adopted the following means in order to achieve the above-mentioned main object.

The power supply device of the present invention
Power storage device and
A boost converter that exchanges power with voltage conversion between the power storage device side and the electric load side.
A current sensor that detects the current flowing through the reactor of the boost converter, and
A control device that controls the boost converter and
It is a power supply device equipped with
The control device controls the boost converter so that when the current detected by the current sensor is large, the amount of change in the current flowing through the reactor per unit time is smaller than when the current is small.
The gist is that.

In the power supply device of the present invention, the boost converter is controlled so that when the current flowing through the reactor of the boost converter (boost current) is large, the amount of change in the current flowing through the reactor per unit time is smaller than when it is small. When the boost current is large, the amount of change in the current flowing through the reactor per unit time is small, so it is possible to suppress the inability to extract power from the battery. On the other hand, when the step-up current is small, the amount of change in the current flowing through the reactor per unit time is large, so that good responsiveness of the step-up current can be obtained. As a result, it is possible to achieve both the extraction of the power supplied from the battery by the boost converter and the responsiveness of the boost current.

In such a power supply device of the present invention, the control device may limit the lower limit of the duty of the boost converter when the current detected by the current sensor is equal to or higher than the current threshold value. In this way, the lower limit of the duty is imposed only when the current (boosting current) flowing through the reactor of the pressure converter is large, and the control can be simplified.

It is a block diagram which shows the outline of the structure of the electric vehicle 20 which mounts the drive device as one Example of this invention. It is a flowchart which shows an example of the duty limitation processing routine executed by the electronic control unit 50 of an Example. It is explanatory drawing which shows an example of the duty in the duty control of the boost converter 40, the switching pattern of the transistors T31 and T32 of the boost converter 40, and the time change of the boost current IL.

Next, a mode for carrying out the present invention will be described with reference to examples.

FIG. 1 is a configuration diagram showing an outline of the configuration of an electric vehicle 20 equipped with a power supply device as an embodiment of the present invention. As shown in the figure, the electric vehicle 20 of the embodiment includes a motor 32, an inverter 34, a battery 36, a boost converter 40, and an electronic control unit 50.

The motor 32 is configured as a synchronous generator motor, and includes a rotor in which a permanent magnet is embedded and a stator in which a three-phase coil is wound. The rotor of the motor 32 is connected to a drive shaft 26 connected to the drive wheels 22a and 22b via a differential gear 24.

The inverter 34 is used to drive the motor 32. The inverter 34 is connected to the boost converter 40 via the high voltage side power line 42, and six diodes D11 to six transistors T11 to T16 and six diodes D11 to T16 connected in parallel to each of the six transistors T11 to T16. It has D16 and. Two transistors T11 to T16 are arranged in pairs so as to be on the source side and the sink side with respect to the positive electrode side line and the negative electrode side line of the high voltage side power line 42, respectively. Further, each of the three-phase coils (U-phase, V-phase, W-phase) of the motor 32 is connected to each of the connection points between the transistors paired with the transistors T11 to T16. Therefore, when a voltage is applied to the inverter 34, the electronic control unit 50 adjusts the ratio of the on-time of the paired transistors T11 to T16, so that a rotating magnetic field is formed in the three-phase coil and the motor. 32 is rotationally driven. A smoothing capacitor 46 is attached to the positive electrode side line and the negative electrode side line of the high voltage side power line 42.

The battery 36 is configured as, for example, a lithium ion secondary battery or a nickel hydrogen secondary battery, and is connected to the boost converter 40 via the low voltage side power line 44. A smoothing capacitor 48 is attached to the positive electrode side line and the negative electrode side line of the low voltage side power line 44.

The boost converter 40 is connected to the high voltage side power line 42 and the low voltage side power line 44, and two diodes connected in parallel to the two transistors T31 and T32 and the two transistors T31 and T32, respectively. It has D31, D32, and a reactor L. The transistor T31 is connected to the positive electrode side line of the high voltage side power line 42. The transistor T32 is connected to the transistor T31 and the negative electrode side line of the high voltage side power line 42 and the low voltage side power line 44. The reactor L is connected to a connection point between the transistors T31 and T32 and a positive electrode side line of the low voltage side power line 44. The boost converter 40 boosts the power of the low voltage side power line 44 and supplies it to the high voltage side power line 42 by adjusting the ratio of the on-time of the transistors T31 and T32 by the electronic control unit 50. The power of the high voltage side power line 42 is stepped down and supplied to the low voltage side power line 44.

The electronic control unit 50 is configured as a microprocessor centered on a CPU 52, and includes a ROM 54 for storing a processing program, a RAM 56 for temporarily storing data, and an input / output port in addition to the CPU 52. Signals from various sensors are input to the electronic control unit 50 via input ports. As the signal input to the electronic control unit 50, for example, the rotation position θm from the rotation position detection sensor (for example, resolver) 32a that detects the rotation position of the rotor of the motor 32, and the current flowing through each phase of the motor 32 are used. The phase currents Iu and Iv from the current sensors 32u and 32v to be detected can be mentioned. Further, a voltage Vb from a voltage sensor (not shown) attached between the terminals of the battery 36 and a current Ib from a current sensor (not shown) attached to the output terminal of the battery 36 can also be mentioned. Further, the boost current IL from the current sensor 41 attached to the input side of the reactor L of the boost converter 40, the converter temperature Tc from the temperature sensor attached to the boost converter 40, and the voltage attached between the terminals of the capacitor 46. The voltage VH of the capacitor 46 (high voltage side power line 42) from the sensor 46a and the voltage VL of the capacitor 48 (low voltage side power line 44) from the voltage sensor 48a attached between the terminals of the capacitor 48 can also be mentioned. .. In addition, the ignition signal from the ignition switch 60 and the shift position SP from the shift position sensor 62 that detects the operation position of the shift lever 61 can also be mentioned. Further, the accelerator opening Acc from the accelerator pedal position sensor 64 that detects the depression amount of the accelerator pedal 63, the brake pedal position BP from the brake pedal position sensor 66 that detects the depression amount of the brake pedal 65, and the vehicle speed sensor 68. The vehicle speed V can also be mentioned.

Various control signals are output from the electronic control unit 50 via the output port. Examples of the signal output from the electronic control unit 50 include a switching control signal for the transistors T11 to T16 of the inverter 34 and a switching control signal for the transistors T31 and T32 of the boost converter 40. The electronic control unit 50 calculates the electric angle θe and the rotation speed Nm of the motor 32 based on the rotation position θm of the rotor of the motor 32 from the rotation position detection sensor 32a. Further, the electronic control unit 50 calculates the storage ratio SOC of the battery 36 based on the integrated value of the current Ib of the battery 36 from a current sensor (not shown). Here, the storage ratio SOC is the ratio of the capacity of electric power that can be discharged from the battery 36 to the total capacity of the battery 36. Further, the electronic control unit 50 calculates the input / output restriction Win and Wout of the battery 36 based on the storage ratio SOC and the battery temperature from a temperature sensor (not shown) attached to the battery 36. The input limit Win is the maximum charge power that can charge the battery 36, and the output limit Wout is the maximum discharge power that can be discharged from the battery 36.

In the electric vehicle 20 of the embodiment configured in this way, the electronic control unit 50 performs the following traveling control. In the travel control, the required torque Td * required for the drive shaft 26 is set based on the accelerator opening Acc and the vehicle speed V, and the required torque Td * is multiplied by the rotation speed Nm of the motor 32 to obtain the travel required power Pd *. Set. Subsequently, the running required power Pd * is limited by the charge / discharge power upper limit value Woutlim obtained by multiplying the input / output limit Win and Wout of the battery 36 by the limit coefficients kin and kout, and the execution power P * is set. The execution torque T * is set by dividing by the rotation speed Nm of the motor 32. Here, the limiting coefficient kin is a coefficient that limits the input limiting Win, and is set in the range of the value 0 to the value 1. The limiting coefficient kout is a coefficient that limits the output limiting Wout, and is set in the range of a value 0 to a value 1. Then, the execution torque T * is set to the torque command Tm * of the motor 32, and the switching control of the transistors T11 to T16 of the inverter 34 is performed so that the motor 32 is driven by the torque command Tm *. Further, in the traveling control, the target voltage VH * of the high voltage side power line 42 is set so that the motor 32 can be driven by the torque command Tm *, and the voltage VH of the high voltage side power line 42 becomes the target voltage VH *. Duty control is performed for switching of the transistors T31 and T32 of the boost converter 40.

Next, the operation of the electric vehicle 20 of the embodiment thus configured is limited to duty control for switching of the transistors T31 and T32 of the boost converter 40 based on the current (boost current) IL flowing through the reactor L of the boost converter 40. The operation when imposing is described. FIG. 2 is a flowchart showing an example of a duty limiting processing routine executed by the electronic control unit 50 of the embodiment. This routine is repeatedly executed at predetermined time intervals (for example, every several tens of ms).

When the duty limit processing routine is executed, the electronic control unit 50 first executes a process of inputting the boosted current IL from the current sensor 41 and the duty command (step S100). In the embodiment, the duty command is set by a duty control routine (not shown) executed by the electronic control unit 50 so that the difference between the voltage VH of the high voltage side power line 42 and the target voltage VH * is canceled. I made it.

Next, it is determined whether or not the input boosted current IL is equal to or greater than the current threshold value Iref (step S110). Here, as the current threshold value Iref, a value having a certain margin with respect to the upper limit of the boosting current that can be tolerated by the boost converter 40 can be used. When it is determined that the boosted current IL is not equal to or greater than the current threshold value Iref, it is determined that it is not necessary to impose any limitation on the duty control, and this routine is terminated.

When it is determined in step S110 that the boosted current IL is equal to or greater than the current threshold value Iref, it is determined whether or not the duty command is less than the lower limit threshold value (step S120). Here, the lower limit threshold value is the duty ratio in the lower limit limit in duty control. When it is determined that the duty command is equal to or higher than the lower limit threshold value, the duty command can be used as it is, and this routine is terminated.

When it is determined in step S120 that the duty command is less than the lower limit threshold value, it is determined that the lower limit limit in duty control is necessary, the lower limit limit (duty limit) in duty control is executed (step S130), and this routine is terminated. .. Duty limitation is achieved by replacing the lower threshold with a duty directive.

FIG. 3 is an explanatory diagram showing an example of the duty in the duty control of the boost converter 40, the switching pattern of the transistors T31 and T32 of the boost converter 40, and the time change of the boost current IL. As shown in the figure, when the duty is a value D1, the off time in the switching pattern, that is, the time when the boost current IL drops is longer than when the duty is a value D2 smaller than the value D1, the boost current is increased. The amount of change in IL per unit time becomes small. If the lower limit of the duty is not limited when the step-up current IL is large, the amount of change in the step-up current IL per unit time becomes large, and the step-up current IL may become excessive. In that case, since an excessive current also flows through the battery 36, it may not be possible to extract power from the battery 36 due to a voltage drop due to the internal resistance of the battery 36. Further, if the boost current IL becomes excessive, the elements of the boost converter 40 and the elements of the inverter 34 may be damaged. Therefore, these inconveniences can be suppressed or avoided by implementing the lower limit limit in the duty control when the step-up current IL is equal to or higher than the current threshold value Iref. On the other hand, when the step-up current IL is less than the current threshold value Iref, the lower limit limit in the duty control is not imposed, so that the responsiveness of the step-up current IL can be improved.

In the power supply device mounted on the electric vehicle 20 of the above-described embodiment, when the boost current IL flowing through the reactor L of the boost converter 40 is equal to or higher than the current threshold Iref, the duty control in switching the transistors T31 and T32 of the boost converter 40 is performed. Imposing a lower limit on duty. As a result, it is possible to prevent the power from being unable to be taken out from the battery 36 when the boosted current IL is equal to or higher than the current threshold Iref, and the responsiveness of the boosted current IL is improved when the boosted current IL is less than the current threshold Iref. It can be good. As a result, it is possible to achieve both the extraction of electric power from the battery 36 by the boost converter 40 and the responsiveness of the boost current IL.

In the power supply device mounted on the electric vehicle 20 of the embodiment, when the boost current IL is less than the current threshold Iref, the lower limit is not imposed on the duty in the duty control of the boost converter 40, and the boost current IL is equal to or more than the current threshold Iref. The lower limit is imposed on the duty in the duty control of the boost converter 40. However, the larger the boost current IL, the lower limit may be imposed on the duty in the duty control of the boost converter 40. That is, the lower limit of the duty may be imposed so that the larger the step-up current IL is, the smaller the amount of change in the step-up current IL per unit time is.

In the electric vehicle 20 of the embodiment, the battery 36 is used as the power storage device, but any device such as a capacitor that can store power may be used.

In the embodiment, the power supply device mounted on the electric vehicle 20 is configured. However, any device may include a power storage device and a boost converter, and may be configured as a power supply device mounted on a hybrid vehicle or a power supply device mounted on non-moving equipment such as construction equipment. ..

Although the embodiments for carrying out the present invention have been described above with reference to examples, the present invention is not limited to these examples, and various embodiments are used without departing from the gist of the present invention. Of course, it can be done.

The present invention can be used in the manufacturing industry of power supply devices and the like.

20 electric vehicle, 22a, 22b drive wheel, 24 differential gear, 26 drive shaft, 32 motor, 32a rotation position detection sensor, 32u, 32v current sensor, 34 inverter, 36 battery, 40 boost converter, 40a temperature sensor, 41 current sensor , 42 high voltage side power line, 44 low voltage side power line, 46,48 capacitor, 46a, 48a voltage sensor, 50 electronic control unit, 52 CPU, 54 ROM, 56 RAM, 60 ignition switch, 61 shift lever, 62 shift Position sensor, 63 accelerator pedal, 64 accelerator pedal position sensor, 65 brake pedal, 66 brake pedal position sensor, 68 vehicle speed sensor, D11 to D16, D31, D32 diode, L reactor, T11 to T16, T31, T32 transistor.

Claims (1)

Power storage device and
A boost converter that exchanges power with voltage conversion between the power storage device side and the electric load side.
A current sensor that detects the current flowing through the reactor of the boost converter, and
A control device that controls the boost converter and
It is a power supply device equipped with
When the current detected by the current sensor is equal to or greater than the current threshold value, the control device limits the lower limit of the duty of the boost converter, so that the current detected by the current sensor is less than the current threshold value. Then, the boost converter is controlled so that the amount of change in the current flowing through the reactor per unit time becomes small.
Power supply.

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