JP2021100341A - Power conversion device - Google Patents

Abstract

To provide a power conversion device capable of suppressing resonance, while suppressing cost.SOLUTION: In a power conversion device having a voltage conversion unit performing a voltage conversion of power supplied from a power supply and outputting to a drive circuit of load, and a control device controlling the drive circuit and the voltage conversion unit, the voltage conversion unit has a switching element controlled by the control device, and the control device performs a first control of stopping a switching operation of the switching element of the voltage conversion unit and directly applying the voltage of the power supply to the drive circuit, a second control of performing a voltage conversion to the voltage of the power supply by the voltage conversion unit and applying to the drive circuit, and changes a drive frequency of the drive circuit upon performing the first control from the drive frequency of the drive circuit upon performing the second control.SELECTED DRAWING: Figure 1

Description

The present invention relates to a power converter.

Conventionally, the VCU (Voltage Control Unit) boosts the output voltage of the battery as DC, and the PDU (Power Drive Unit) converts the DC voltage boosted by the VUC into AC voltage and supplies it to the motor generator. A PCU (Power Control Unit) is known in which a (Motor Electronic Control Unit) outputs a control signal of a switching element of a VCU and a PDU (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2013-115957

By the way, Patent Document 1 does not describe a method for avoiding that the switching frequency of the PDU and the resonance frequency of the PCU match. If a hardware component is added as a resonance avoidance means, the cost may increase.

In view of the above-mentioned problems, an object of the present invention is to provide a power conversion device capable of suppressing resonance while suppressing costs.

(1) The power conversion device according to one aspect of the present invention controls a voltage conversion unit that performs voltage conversion of power supplied from a power source and outputs the voltage to a load drive circuit, and controls the drive circuit and the voltage conversion unit. In a power conversion device including a control device, the voltage conversion unit includes a switching element controlled by the control device, and the control device stops the switching operation of the switching element of the voltage conversion unit. The first control in which the voltage of the power supply is directly applied to the drive circuit and the second control in which the voltage of the power supply is voltage-converted by the voltage conversion unit and applied to the drive circuit are performed, and the first control is performed. The power conversion device is characterized in that the drive frequency of the drive circuit when performing the control of the above is changed from the drive frequency of the drive circuit when the second control is performed.

(2) In the power conversion device according to (1) above, the drive frequency of the drive circuit when performing the first control is higher than the drive frequency of the drive circuit when performing the second control. You may.

(3) In the power conversion device according to (2) above, the drive frequency of the drive circuit when the drive power of the drive circuit is smaller than the threshold value is set as the drive frequency of the drive circuit when the drive power of the drive circuit is equal to or more than the threshold value. It may be higher than the drive frequency of the drive circuit.

(4) In the power conversion device according to (2) above, the drive frequency of the drive circuit when performing the first control is higher than the resonance frequency of the power conversion device when performing the first control. However, the frequency may be higher than the resonance frequency of the power converter when performing the second control.

(5) In the power conversion device according to (4) above, the drive frequency of the drive circuit when performing the second control is higher than the resonance frequency of the power conversion device when performing the first control. However, the frequency may be lower than the resonance frequency of the power converter when performing the second control.

(6) In the power conversion device according to (1) above, the control device determines whether to perform the first control or the second control, and the power conversion device. A second determination is made as to whether or not the operating state is included in the resonance region, and the control device performs the first control, and the operating state of the power conversion device is included in the resonance region. In addition, the drive frequency of the drive circuit when performing the second control may be changed to the drive frequency of the drive circuit when performing the first control.

(7) In the power conversion device according to (6) above, the control device performs the second control, or when the operating state of the power conversion device is not included in the resonance region, the above. The drive frequency of the drive circuit when performing the second control may be maintained.

(8) In the power conversion device according to any one of (1) to (7) above, the drive circuit includes a switching element for the drive circuit, and the switching element for the drive circuit is formed of a wide bandgap semiconductor. You may.

In the power conversion device described in (1) above, the control device that controls the load drive circuit and the voltage conversion unit that performs voltage conversion of the power supplied from the power supply stops the switching operation of the switching element of the voltage conversion unit. Then, the first control in which the voltage of the power supply is directly applied to the drive circuit and the second control in which the voltage of the power supply is voltage-converted by the voltage conversion unit and applied to the drive circuit are performed. The control device changes the drive frequency of the drive circuit when performing the first control from the drive frequency of the drive circuit when performing the second control.
Therefore, in the power conversion device described in (1) above, the drive frequency of the drive circuit when performing the first control and the resonance frequency of the power conversion device when performing the first control are different from each other, and the first control is performed. By making the drive frequency of the drive circuit when performing the second control different from the resonance frequency of the power conversion device when performing the second control, resonance occurs while suppressing the addition of hardware components as resonance avoidance means. Can be suppressed. That is, resonance can be suppressed while suppressing cost.

In the power conversion device according to (2) and (3) above, the drive frequency of the drive circuit when performing the first control is set to be higher than the drive frequency of the drive circuit when performing the second control, or , The drive frequency of the drive circuit when the drive power of the drive circuit is smaller than the threshold value may be higher than the drive frequency of the drive circuit when the drive power of the drive circuit is equal to or more than the threshold value.
In such a configuration, when the load is a motor, the motor is driven by increasing the drive frequency of the drive circuit when performing the first control (when the drive power of the drive circuit is smaller than the threshold value). Efficiency can be improved.

In the power conversion device according to (4) above, the drive frequency of the drive circuit when performing the first control is set higher than the resonance frequency of the power conversion device when performing the first control, and the second control is performed. It may be higher than the resonance frequency of the power converter when performing control.
In such a configuration, the possibility that the power conversion device resonates when performing the first control is suppressed, and the motor efficiency when performing the first control when the load is a motor is improved. be able to.

In the power conversion device according to (5) above, the drive frequency of the drive circuit when performing the second control is set higher than the resonance frequency of the power conversion device when performing the first control, and the second control is performed. It may be lower than the resonance frequency of the power converter when performing control.
In such a configuration, it is possible to suppress the possibility that the power conversion device resonates when performing the second control.

In the power conversion device according to (6) and (7) above, when the first control is performed and the operating state of the power conversion device is included in the resonance region, the drive circuit for performing the second control When the drive frequency is changed to the drive frequency of the drive circuit when the first control is performed and the second control is performed or the operating state of the power converter is not included in the resonance region, the second control is performed. The drive frequency of the drive circuit when controlling the above may be maintained.
That is, in the power conversion device according to (6) and (7) above, even when the first control is performed, the second control is performed when the operating state of the power conversion device is not included in the resonance region. The drive frequency of the drive circuit when performing the first control may not be changed to the drive frequency of the drive circuit when performing the first control, and the drive frequency of the drive circuit when performing the second control may be maintained. ..
In such a case, although it is not necessary to change the drive frequency of the drive circuit when performing the second control to the drive frequency of the drive circuit when performing the first control, the second control is performed. It is possible to avoid a change from the drive frequency of the drive circuit when performing the control of the above to the drive frequency of the drive circuit when performing the first control, that is, unnecessary control is performed. be able to.

In the power conversion device according to (8) above, the drive circuit switching element provided in the drive circuit may be formed of a wide bandgap semiconductor. Wide bandgap semiconductors include, for example, silicon carbide, gallium nitride based materials, gallium oxide based materials, diamond and the like.
In such a case, the drive frequency of the drive circuit switching element of the drive circuit when performing the first control is set to the drive frequency of the drive circuit switching element of the drive circuit when performing the second control. When the value is higher, the resonance of the power converter can be suppressed without lowering the overall efficiency.

It is a figure which shows an example of the schematic structure of the power conversion apparatus of 1st Embodiment. It is a figure which shows an example of the drive frequency of the drive circuit set by the control device of the power conversion apparatus of 1st Embodiment. It is a flowchart for demonstrating an example of the process executed in the power conversion apparatus of 1st Embodiment. It is a flowchart for demonstrating an example of the process executed in the power conversion apparatus of 2nd Embodiment. It is a figure which shows an example of a part of the vehicle which can apply the power conversion apparatus of 1st and 2nd Embodiment. It is a figure which shows the relationship between the drive frequency (switching frequency), and the efficiency of the upper arm element and the lower arm element (switching element for a drive circuit) of the 1st power conversion circuit part (drive circuit) in the vehicle shown in FIG. It is a figure which shows an example of the connection method of the power electronics component in a recent vehicle.

Hereinafter, embodiments of the power conversion device of the present invention will be described with reference to the accompanying drawings.

<First Embodiment>
FIG. 1 is a diagram showing an example of a schematic configuration of the power conversion device 1 of the first embodiment.
In the example shown in FIG. 1, the power conversion device 1 performs voltage conversion of the power supplied from the power supply PS and the like. The power conversion device 1 includes a voltage conversion unit 11 and a control device 12.
The voltage conversion unit 11 performs voltage conversion of the power supplied from the power supply PS. Further, the voltage conversion unit 11 outputs the electric power after the voltage conversion is performed to the drive circuit DT of the load LD. The voltage conversion unit 11 includes a switching element 11A controlled by the control device 12.
The control device 12 controls the voltage conversion unit 11 and the drive circuit DT. Specifically, the control device 12 controls the switching element 11A of the voltage conversion unit 11 and the drive circuit switching element DTS provided in the drive circuit DT. The drive circuit switching element DTS is formed of a wide bandgap semiconductor such as silicon carbide, gallium nitride-based material, gallium oxide-based material, or diamond. In another example, the drive circuit switching element DTS may not be formed of a wide bandgap semiconductor.
In the example shown in FIG. 1, the drive circuit DT is not included in the power conversion device 1, but in another example, the drive circuit DT may be included in the power conversion device 1.

In the example shown in FIG. 1, the power conversion device 1 has a direct connection operation mode and a normal operation mode.
In the direct connection operation mode of the power conversion device 1, the switching element 11A does not perform the switching operation, and as a result, the voltage conversion unit 11 directly applies the voltage of the power supply PS to the drive circuit DT without performing voltage conversion. That is, in the direct connection operation mode of the power conversion device 1, the control device 12 stops the switching operation of the switching element 11A of the voltage conversion unit 11 (specifically, the boosting operation or the voltage conversion operation of the voltage conversion unit 11) to supply power. The first control of applying the PS voltage directly to the drive circuit DT is performed.
In the normal operation mode of the power conversion device 1, the switching element 11A performs a switching operation, and as a result, the voltage conversion unit 11 converts the voltage of the power supply PS into a voltage and applies it to the drive circuit DT. That is, in the normal operation mode of the power conversion device 1, the control device 12 causes the switching element 11A of the voltage conversion unit 11 to perform a switching operation (specifically, a boost operation or a voltage conversion operation of the voltage conversion unit 11) to supply power. A second control is performed in which the PS voltage is voltage-converted and applied to the drive circuit DT.

FIG. 2 shows the drive frequencies fA and fB of the drive circuit DT set by the control device 12 of the power conversion device 1 of the first embodiment (operating frequencies (switching frequencies) fA and fB of the switching element DTS for the drive circuit of the drive circuit DT). ), Etc. are shown in the figure. In FIG. 2, the horizontal axis represents the frequency f [Hz], and the vertical axis represents the gain. Further, in FIG. 2, the point A indicates the resonance point in the normal operation mode of the power conversion device 1, the point B indicates the resonance point in the direct connection operation mode of the power conversion device 1, and the frequency RfA indicates the power. The resonance frequencies of the plurality of interconnected power components in the normal operation mode of the converter 1 are shown, and the frequency RfB is the resonance of the plurality of interconnected power components in the direct operation mode of the power converter 1. Indicates the frequency.
In the examples shown in FIGS. 1 and 2, when the control device 12 performs the first control (that is, in the direct connection operation mode of the power conversion device 1), the drive frequency fB of the drive circuit DT (switching element DTS for the drive circuit). The operating frequency (switching frequency) fB) and the drive frequency fA (switching element DTS for the drive circuit) of the drive circuit DT when the control device 12 performs the second control (that is, in the normal operation mode of the power conversion device 1). The operating frequency (switching frequency) fA) is different.
Specifically, when the control device 12 performs the first control (in the direct connection operation mode of the power conversion device 1), the drive frequency fB of the drive circuit DT (switching frequency fB of the switching element DTS for the drive circuit) is the control device. It is higher than the drive frequency fA of the drive circuit DT (switching frequency fA of the switching element DTS for the drive circuit) when the 12 performs the second control (in the normal operation mode of the power conversion device 1).

That is, in the examples shown in FIGS. 1 and 2, the control device 12 sets the drive frequency fB of the drive circuit DT when performing the first control from the drive frequency fA of the drive circuit DT when performing the second control. change.
Further, in the examples shown in FIGS. 1 and 2, the drive frequency fB of the drive circuit DT when the control device 12 performs the first control is the power conversion device 1 when the control device 12 performs the first control. It is higher than the resonance frequency RfB and higher than the resonance frequency RfA of the power conversion device 1 when the control device 12 performs the second control.
Further, in the examples shown in FIGS. 1 and 2, the drive frequency fA of the drive circuit DT when the control device 12 performs the second control is the power conversion device 1 when the control device 12 performs the first control. It is higher than the resonance frequency RfB and lower than the resonance frequency RfA of the power conversion device 1 when the control device 12 performs the second control.

FIG. 3 is a flowchart for explaining an example of processing executed in the power conversion device 1 of the first embodiment.
In the example shown in FIG. 3, in step S11, the control device 12 executes the operation mode determination (determination of whether the power conversion device 1 is in the direct connection operation mode or the normal operation mode).
Specifically, in step S11, the control device 12 determines, for example, whether the drive power of the drive circuit DT is smaller than the threshold value or greater than or equal to the threshold value. When the drive power of the drive circuit DT is smaller than the threshold value, the control device 12 determines that the power conversion device 1 is in the direct connection operation mode. When the drive power of the drive circuit DT is equal to or greater than the threshold value, the control device 12 determines that the power conversion device 1 is in the normal operation mode.

Next, in step S12, the control device 12 determines whether or not the power conversion device 1 is in the direct connection operation mode based on the determination result in step S11. If the power conversion device 1 is not in the direct connection operation mode, the process proceeds to step S13. On the other hand, when the power conversion device 1 is in the direct connection operation mode, the process proceeds to step S14.
In step S13, the control device 12 causes the switching element 11A of the voltage conversion unit 11 to perform a switching operation (specifically, a boosting operation or a voltage conversion operation of the voltage conversion unit 11) to convert the voltage of the power supply PS into a voltage. The second control applied to the drive circuit DT is performed, and the drive circuit DT is operated at the drive frequency fA (that is, the drive circuit switching element DTS is operated at the switching frequency fA).
Specifically, the control device 12 maintains the drive frequency of the drive circuit DT at a drive frequency fA preset as a default value.
In step S14, the control device 12 stops the switching operation of the switching element 11A of the voltage conversion unit 11 (specifically, the boosting operation or the voltage conversion operation of the voltage conversion unit 11) to transfer the voltage of the power supply PS to the drive circuit DT. The first control to be applied directly is performed, and the drive circuit DT is operated at the drive frequency fB (that is, the drive circuit switching element DTS is operated at the switching frequency fB).
Specifically, the control device 12 changes the drive frequency of the drive circuit DT from the drive frequency fA preset as a default value to the drive frequency fB.

That is, in the example shown in FIGS. 1 to 3, when the control device 12 performs the first control (in the direct connection operation mode of the power conversion device 1), the drive frequency fB of the drive circuit DT is set to that of the power conversion device 1. It is set to a value that avoids the resonance frequency RfB corresponding to the resonance point B in the direct connection operation mode. Specifically, in the direct connection operation mode of the power conversion device 1, the drive frequency fB of the drive circuit DT is set to a value higher than the resonance frequency RfB corresponding to the resonance point B in the direct connection operation mode of the power conversion device 1. Therefore, it is possible to suppress the possibility that the power conversion device 1 resonates when the control device 12 performs the first control (in the direct connection operation mode of the power conversion device 1).
Further, when the control device 12 performs the second control (in the normal operation mode of the power conversion device 1), the drive frequency fA of the drive circuit DT corresponds to the resonance point A in the normal operation mode of the power conversion device 1. It is set to a value that avoids the resonance frequency RfA. Specifically, in the normal operation mode of the power conversion device 1, the drive frequency fA of the drive circuit DT is set to a value lower than the resonance frequency RfA corresponding to the resonance point A in the normal operation mode of the power conversion device 1. Therefore, it is possible to suppress the possibility that the power conversion device 1 resonates when the control device 12 performs the second control (in the normal operation mode of the power conversion device 1).

Specifically, in the example shown in FIGS. 1 to 3, when the control device 12 performs the first control (in the direct connection operation mode of the power conversion device 1), the drive frequency fB of the drive circuit DT is set by the control device 12. It is higher than the drive frequency fA of the drive circuit DT when the second control is performed (in the normal operation mode of the power conversion device 1).
In other words, the drive frequency fB of the drive circuit DT when the drive power of the drive circuit DT is smaller than the threshold value is higher than the drive frequency fA of the drive circuit DT when the drive power of the drive circuit DT is equal to or more than the threshold value.
Therefore, in the example shown in FIGS. 1 to 3, when the load LD is a motor, the drive frequency of the drive circuit DT when the control device 12 performs the first control (in the direct connection operation mode of the power conversion device 1). By making fB higher than the drive frequency fA, the motor efficiency can be improved. (As will be described later with reference to FIG. 6, the higher the drive frequency of the drive circuit DT of the motor, the higher the motor efficiency.)

Further, in the examples shown in FIGS. 1 to 3, the drive circuit switching element DTS is formed of a wide bandgap semiconductor. Therefore, the drive frequency fB of the drive circuit switching element DTS of the drive circuit DT in the direct connection operation mode of the power conversion device 1 is set to drive the drive circuit switching element DTS of the drive circuit DT in the normal operation mode of the power conversion device 1. Even if the frequency is higher than fA, the total efficiency does not change significantly. That is, the drive frequency fB of the drive circuit switching element DTS of the drive circuit DT in the direct connection operation mode of the power conversion device 1 is driven by the drive circuit switching element DTS of the drive circuit DT in the normal operation mode of the power conversion device 1. By making the frequency higher than fA, the resonance of the power conversion device 1 can be suppressed without lowering the overall efficiency. (As will be described later with reference to FIG. 6, when the drive circuit switching element DTS is formed of a semiconductor other than the wideband gap semiconductor (for example, Si semiconductor), the drive frequency of the drive circuit DT of the motor. When the value is high, the efficiency of the drive circuit DT of the motor is greatly reduced, whereas when the switching element DTS for the drive circuit is formed of a wideband gap semiconductor, the drive frequency of the drive circuit DT of the motor is high. However, the efficiency of the drive circuit DT of the motor does not decrease significantly.)

<Second Embodiment>
Hereinafter, a second embodiment of the power conversion device of the present invention will be described.
The power conversion device 1 of the second embodiment is configured in the same manner as the power conversion device 1 of the first embodiment described above, except for the points described later. Therefore, according to the power conversion device 1 of the second embodiment, the same effect as that of the power conversion device 1 of the first embodiment described above can be obtained except for the points described later.

The power conversion device 1 of the second embodiment is configured in the same manner as the power conversion device 1 of the first embodiment shown in FIG.
In the power conversion device 1 of the first embodiment, the drive frequency of the drive circuit DT is set to the frequency fA (see FIG. 2) in the normal operation mode of the power conversion device 1, and the drive circuit DT is set in the direct connection operation mode of the power conversion device 1. The drive frequency of is set to the frequency fB (see FIG. 2).
On the other hand, in the power conversion device 1 of the second embodiment, in the normal operation mode of the power conversion device 1, the drive frequency of the drive circuit DT is the frequency fA (see FIG. 2) as in the power conversion device 1 of the first embodiment. However, in the direct connection operation mode of the power conversion device 1, unlike the power conversion device 1 of the first embodiment, the drive frequency of the drive circuit DT may not be set to the frequency fB (see FIG. 2).

FIG. 4 is a flowchart for explaining an example of processing executed in the power conversion device 1 of the second embodiment.
In the example shown in FIG. 4, in step S21, similarly to step S11 in FIG. 3, the control device 12 determines the operation mode (determines whether the power conversion device 1 is in the direct connection operation mode or the normal operation mode. ) Is executed.

Next, in step S22, the control device 12 determines whether or not the power conversion device 1 is in the direct connection operation mode based on the determination result in step S21. If the power conversion device 1 is not in the direct connection operation mode, the process proceeds to step S23. On the other hand, when the power conversion device 1 is in the direct connection operation mode, the process proceeds to step S24.
In step S23, similarly to step S13 of FIG. 3, the control device 12 causes the switching element 11A of the voltage conversion unit 11 to perform a switching operation (specifically, a boosting operation or a voltage conversion operation of the voltage conversion unit 11). The second control of converting the voltage of the power supply PS into a voltage and applying it to the drive circuit DT is performed, and the drive circuit DT is operated at the drive frequency fA (that is, the drive circuit switching element DTS is operated at the switching frequency fA).
Specifically, the control device 12 maintains the drive frequency of the drive circuit DT at a drive frequency fA preset as a default value.

In step S24, the control device 12 executes resonance determination (determination of whether the operating state of the power conversion device 1 is included in the resonance region or the operating state of the power conversion device 1 is not included in the resonance region).
Specifically, in step S24, the control device 12 causes the control device 12 to operate the drive circuit DT at the drive frequency fA based on information such as the voltage applied to the power conversion device 1 and the current flowing through the power conversion device 1. And, it is determined whether or not the power conversion device 1 may resonate. When the control device 12 operates the drive circuit DT at the drive frequency fA and the power conversion device 1 may resonate, the control device 12 determines that the operating state of the power conversion device 1 is included in the resonance region. .. On the other hand, if there is no risk of the power conversion device 1 resonating even if the control device 12 operates the drive circuit DT at the drive frequency fA, the control device 12 includes the operating state of the power conversion device 1 in the resonance region. Judge that it cannot be done.

Next, in step S25, the control device 12 determines whether or not the operating state of the power conversion device 1 is included in the resonance region based on the determination result in step S24.
When the operating state of the power conversion device 1 is not included in the resonance region, the process proceeds to step S23, and the control device 12 performs a switching operation of the switching element 11A of the voltage conversion unit 11 (specifically, boosting the voltage conversion unit 11). The operation or voltage conversion operation is stopped to perform the first control of directly applying the voltage of the power supply PS to the drive circuit DT, and the drive circuit DT is operated at the drive frequency fA (that is, the drive circuit switching element DTS is operated. Operate at switching frequency fA).
On the other hand, when the operating state of the power conversion device 1 is included in the resonance region, the process proceeds to step S26.

In step S26, similarly to step S14 of FIG. 3, the control device 12 stops the switching operation of the switching element 11A of the voltage conversion unit 11 (specifically, the boosting operation or the voltage conversion operation of the voltage conversion unit 11). The first control of directly applying the voltage of the power supply PS to the drive circuit DT is performed, and the drive circuit DT is operated at the drive frequency fB (that is, the drive circuit switching element DTS is operated at the switching frequency fB).
Specifically, the control device 12 changes the drive frequency of the drive circuit DT from the drive frequency fA preset as a default value to the drive frequency fB.

That is, in the example shown in FIG. 4, whether the control device 12 performs the first control (in the direct connection operation mode) or the second control (in the normal operation mode). The determination (operation mode determination) and the determination (resonance determination) of whether or not the operating state of the power conversion device 1 is included in the resonance region are performed.
When the control device 12 performs the first control (in the direct connection operation mode of the power conversion device 1) and when the operation state of the power conversion device 1 is included in the resonance region, the control device 12 controls the second control. From the drive frequency fA of the drive circuit DT when performing the operation (in the normal operation mode of the power conversion device 1) to the drive frequency fB of the drive circuit DT when performing the first control (in the direct connection operation mode of the power conversion device 1). Make changes to.

Further, in the example shown in FIG. 4, when the control device 12 performs the second control (in the normal operation mode of the power conversion device 1), or when the operation state of the power conversion device 1 is not included in the resonance region. , The control device 12 maintains the drive frequency of the drive circuit DT at a drive frequency fA preset as a default value.
That is, in the example shown in FIG. 4, the operating state of the power conversion device 1 is not included in the resonance region even when the control device 12 performs the first control (in the direct connection operation mode of the power conversion device 1). In this case, since it is not necessary to suppress the resonance of the power conversion device 1, the drive frequency fA of the drive circuit DT when the control device 12 performs the second control (in the normal operation mode of the power conversion device 1) is determined. When the control device 12 performs the first control (in the direct connection operation mode of the power conversion device 1), the drive frequency fB of the drive circuit DT is not changed.
As a result, in the example shown in FIG. 4, it is possible to avoid unnecessary control.

<Application example>
FIG. 5 is a diagram showing an example of a part of a vehicle 10 to which the power conversion device 1 of the first and second embodiments can be applied.
In the example shown in FIG. 5, in addition to the power conversion device 1, the vehicle 10 has a battery (BATT) that functions as a power supply PS, a first motor (MOT) for driving that functions as a load LD, and a first motor for power generation. It is equipped with two motors 13 (GEN).
The battery (power supply PS) includes a battery case and a plurality of battery modules housed in the battery case. The battery module includes a plurality of battery cells connected in series. The battery (power supply PS) includes a positive electrode terminal PB and a negative electrode terminal NB connected to the DC connector 1a. The positive electrode terminal PB and the negative electrode terminal NB are connected to the positive electrode end and the negative electrode end of a plurality of battery modules connected in series in the battery case.

The first motor (load LD) generates a rotational driving force (power running operation) by the electric power supplied from the battery (power supply PS). The second motor 13 generates generated electric power by the rotational driving force input to the rotary shaft. Here, the second motor 13 is configured to be able to transmit the rotational power of the internal combustion engine. For example, each of the first motor (load LD) and the second motor 13 is a three-phase AC brushless DC motor. The three phases are the U phase, the V phase, and the W phase. Each of the first motor (load LD) and the second motor 13 is an inner rotor type. The first motor (load LD) and the second motor 13 have a rotor having a permanent magnet for a field magnet and a stator having a three-phase stator winding for generating a rotating magnetic field for rotating the rotor. Each has. The three-phase stator windings of the first motor (load LD) are connected to the first three-phase connector 1b. The three-phase stator windings of the second motor 13 are connected to the second three-phase connector 1c.

The vehicle 10 shown in FIG. 5 includes a power module 21, a reactor 22, a capacitor unit 23, a resistor 24, a first current sensor 25, a second current sensor 26, a third current sensor 27, and electronic control. It includes a unit 28 (MOT GEN ECU) and a gate drive unit (G / D VCU ECU) that functions as a control device 12.
The power module 21 includes a first power conversion circuit unit that functions as a drive circuit DT, a second power conversion circuit unit 32, and a third power conversion circuit unit that functions as a voltage conversion unit 11.

The output-side conductor (output bus bar) 51 of the first power conversion circuit unit (drive circuit DT) is grouped into three phases of U-phase, V-phase, and W-phase, and is connected to the first three-phase connector 1b. There is. That is, the output-side conductor 51 of the first power conversion circuit unit (drive circuit DT) is connected to the three-phase stator winding of the first motor (load LD) via the first three-phase connector 1b. ..
The positive electrode side conductor (P bus bar) PI of the first power conversion circuit unit (drive circuit DT) is grouped into three phases of U phase, V phase and W phase, and is connected to the positive electrode terminal PB of the battery (power supply PS). Has been done.
The negative electrode side conductor (N bus bar) NI of the first power conversion circuit unit (drive circuit DT) is grouped into three phases of U phase, V phase and W phase, and is connected to the negative electrode terminal NB of the battery (power supply PS). Has been done.
That is, the first power conversion circuit unit (drive circuit DT) converts the DC power input from the battery (power supply PS) via the third power conversion circuit unit (voltage conversion unit 11) into three-phase AC power.

The output-side conductor (output bus bar) 52 of the second power conversion circuit unit 32 is grouped into three phases of U phase, V phase, and W phase, and is connected to the second three-phase connector 1c. That is, the output-side conductor 52 of the second power conversion circuit unit 32 is connected to the three-phase stator winding of the second motor 13 via the second three-phase connector 1c.
The positive electrode side conductor (P bus bar) PI of the second power conversion circuit unit 32 is integrated into three phases of U phase, V phase and W phase, and is combined with the positive electrode terminal PB of the battery (power supply PS) and the first power conversion. It is connected to the positive electrode side conductor PI of the circuit unit (drive circuit DT).
The negative electrode side conductor (N bus bar) NI of the second power conversion circuit unit 32 is integrated into three phases of U phase, V phase and W phase, and is combined with the negative electrode terminal NB of the battery (power supply PS) and the second power conversion. It is connected to the negative electrode side conductor NI of the circuit unit 32.
The second power conversion circuit unit 32 converts the three-phase AC power input from the second motor 13 into DC power. The DC power converted by the second power conversion circuit unit 32 can be supplied to at least one of the battery (power supply PS) and the first power conversion circuit unit (drive circuit DT).

In the example shown in FIG. 5, the U-phase upper arm element UH, the V-phase upper arm element VH, and the W-phase upper arm element WH that function as the switching element DTS for the drive circuit of the first power conversion circuit unit (drive circuit DT) are It is connected to the positive electrode side conductor PI. Further, the U-phase upper arm element UH, the V-phase upper arm element VH, and the W-phase upper arm element WH of the second power conversion circuit unit 32 are connected to the positive electrode side conductor PI. The positive electrode side conductor PI is connected to the positive electrode terminal (positive electrode bus bar) 50p of the capacitor unit 23.
The U-phase lower arm element UL, the V-phase lower arm element VL, and the W-phase lower arm element WL, which function as the switching element DTS for the drive circuit of the first power conversion circuit unit (drive circuit DT), are connected to the negative electrode side conductor NI. Has been done. Further, the U-phase lower arm element UL, the V-phase lower arm element VL, and the W-phase lower arm element WL of the second power conversion circuit unit 32 are connected to the negative electrode side conductor NI. The negative electrode side conductor NI is connected to the negative electrode terminal (negative electrode bus bar) 50n of the capacitor unit 23.

In the example shown in FIG. 5, the connection point TI between the U-phase upper arm element UH and the U-phase lower arm element UL of the first power conversion circuit unit (drive circuit DT), and the V-phase upper arm element VH and the V-phase lower arm. The connection point TI with the element VL and the connection point TI between the W phase upper arm element WH and the W phase lower arm element WL are connected to the output side conductor 51.
The connection point TI between the U-phase upper arm element UH and the U-phase lower arm element UL of the second power conversion circuit unit 32, the connection point TI between the V-phase upper arm element VH and the V-phase lower arm element VL, and the W phase. The connection point TI between the upper arm element WH and the W phase lower arm element WL is connected to the output side conductor 52.

In the example shown in FIG. 5, the output-side conductor 51 of the first power conversion circuit unit (drive circuit DT) is connected to the first input / output terminal Q1. The first input / output terminal Q1 is connected to the first three-phase connector 1b. The connection point TI of each phase of the first power conversion circuit unit (drive circuit DT) is a first motor (load LD) via the output side conductor 51, the first input / output terminal Q1, and the first three-phase connector 1b. ) Is connected to the stator windings of each phase.
The output-side conductor 52 of the second power conversion circuit unit 32 is connected to the second input / output terminal Q2. The second input / output terminal Q2 is connected to the second three-phase connector 1c. The connection point TI of each phase of the second power conversion circuit unit 32 is a stator winding of each phase of the second motor 13 via the output side conductor 52, the second input / output terminal Q2, and the second three-phase connector 1c. It is connected to the wire.

In the example shown in FIG. 5, the upper arm elements UH, VH, WH (switching element DTS for the drive circuit) and the lower arm elements UL, VL, WL (switching element for the drive circuit) of the first power conversion circuit unit (drive circuit DT) Each of the DTSs) has a flywheel diode connected in antiparallel.
Similarly, each of the upper arm elements UH, VH, WH and the lower arm elements UL, VL, and WL of the second power conversion circuit unit 32 includes flywheel diodes connected in antiparallel.

In the example shown in FIG. 5, the gate drive unit (control device 12) has upper arm elements UH, VH, WH (switching element DTS for drive circuit) and lower arm element UL of the first power conversion circuit unit (drive circuit DT). Gate signals are input to each of VL and WL (switching element DTS for drive circuit).
Similarly, the gate drive unit (control device 12) inputs a gate signal to each of the upper arm elements UH, VH, WH and the lower arm elements UL, VL, and WL of the second power conversion circuit unit 32.
The first power conversion circuit unit (drive circuit DT) converts the DC power input from the battery (power supply PS) via the third power conversion circuit unit (voltage conversion unit 11) into three-phase AC power, and first AC U-phase current, V-phase current, and W-phase current are supplied to the three-phase stator windings of the motor (load LD). The second power conversion circuit unit 32 turns on the upper arm elements UH, VH, WH and the lower arm elements UL, VL, and WL of the second power conversion circuit unit 32, which are synchronized with the rotation of the second motor 13. By (conduction) / off (disconnection) drive, the three-phase AC power output from the three-phase stator windings of the second motor 13 is converted into DC power.

The third power conversion circuit unit (voltage conversion unit 11) is a voltage control unit (VCU). The third power conversion circuit unit (voltage conversion unit 11) includes an upper arm element S1 and a lower arm element S2 for one phase that function as the switching element 11A.

The electrode on the positive electrode side of the upper arm element S1 (switching element 11A) is connected to the positive electrode bus bar PV. The positive electrode bus bar PV is connected to the positive electrode terminal (positive electrode bus bar) 50p of the capacitor unit 23. The electrode on the negative electrode side of the lower arm element S2 (switching element 11A) is connected to the negative electrode bus bar NV. The negative electrode bus bar NV is connected to the negative electrode terminal (negative electrode bus bar) 50n of the capacitor unit 23. The negative electrode terminal 50n of the capacitor unit 23 is connected to the negative electrode terminal NB of the battery (power supply PS). The electrode on the negative electrode side of the upper arm element S1 (switching element 11A) is connected to the electrode on the positive electrode side of the lower arm element S2 (switching element 11A). The upper arm element S1 and the lower arm element S2 include a flywheel diode.

The bus bar 53 constituting the connection point between the upper arm element S1 and the lower arm element S2 of the third power conversion circuit unit (voltage conversion unit 11) is connected to one end of the reactor 22. The other end of the reactor 22 is connected to the positive electrode terminal PB of the battery (power supply PS). The reactor 22 includes a coil and a temperature sensor that detects the temperature of the coil. The temperature sensor is connected to the electronic control unit 28 by a signal line.

The third power conversion circuit unit (voltage conversion unit 11) inputs from the gate drive unit (control device 12) to the gate electrode of the upper arm element S1 (switching element 11A) and the gate electrode of the lower arm element S2 (switching element 11A). Based on the gate signal, the upper arm element S1 (switching element 11A) and the lower arm element S2 (switching element 11A) are switched on (conducting) / off (blocking).

In the third power conversion circuit unit (voltage conversion unit 11), the lower arm element S2 (switching element 11A) is set to on (conduction) and the upper arm element S1 (switching element 11A) is set to off (block) during boosting. The first state is alternately switched between the second state in which the lower arm element S2 (switching element 11A) is set to off (block) and the upper arm element S1 (switching element 11A) is set to on (conduction). In the first state, a current flows sequentially to the positive electrode terminal PB of the battery (power supply PS), the reactor 22, the lower arm element S2 (switching element 11A), and the negative electrode terminal NB of the battery (power supply PS), and the reactor 22 is DC excited. And magnetic energy is stored. In the second state, an electromotive voltage (induced voltage) is generated between both ends of the reactor 22 so as to prevent a change in magnetic flux due to the interruption of the current flowing through the reactor 22. The induced voltage due to the magnetic energy stored in the reactor 22 is superimposed on the battery voltage, and the boosted voltage higher than the voltage between the terminals of the battery (power supply PS) is the positive voltage bus bar PV of the third power conversion circuit unit (voltage conversion unit 11). It is applied between the negative voltage bus bar NV and the negative voltage bus bar NV.

The third power conversion circuit unit (voltage conversion unit 11) alternately switches between the second state and the first state at the time of regeneration. In the second state, currents are sequentially applied to the positive electrode bus bar PV of the third power conversion circuit unit (voltage conversion unit 11), the upper arm element S1 (switching element 11A), the reactor 22, and the positive electrode terminal PB of the battery (power supply PS). As the current flows, the reactor 22 is DC excited and magnetic energy is stored. In the first state, an electromotive voltage (induced voltage) is generated between both ends of the reactor 22 so as to prevent a change in magnetic flux due to the interruption of the current flowing through the reactor 22. The induced voltage due to the magnetic energy stored in the reactor 22 is stepped down, and the step-down voltage lower than the voltage between the positive electrode bus bar PV and the negative electrode bus bar NV of the third power conversion circuit unit (voltage conversion unit 11) is the battery (power supply PS). It is applied between the positive electrode terminal PB and the negative electrode terminal NB.

The capacitor unit 23 includes a first smoothing capacitor 41, a second smoothing capacitor 42, and a noise filter 43.

The first smoothing capacitor 41 is connected between the positive electrode terminal PB and the negative electrode terminal NB of the battery (power supply PS). The first smoothing capacitor 41 is used for on / off switching operation of the upper arm element S1 (switching element 11A) and the lower arm element S2 (switching element 11A) at the time of regeneration of the third power conversion circuit unit (voltage conversion unit 11). Smooths out the voltage fluctuations that accompany it.
The second smoothing capacitor 42 is provided between the positive electrode side conductor PI and the negative electrode side conductor NI of the first power conversion circuit unit (drive circuit DT) and the second power conversion circuit unit 32, and the third power conversion circuit unit (3rd power conversion circuit unit). It is connected between the positive electrode bus bar PV and the negative electrode bus bar NV of the voltage conversion unit 11). The second smoothing capacitor 42 is connected to a plurality of positive electrode side conductor PI and negative electrode side conductor NI, and positive electrode side conductor PV and negative electrode bus bar NV via a positive electrode terminal (positive electrode bus bar) 50p and a negative electrode terminal (negative electrode bus bar) 50n. Has been done. The second smoothing capacitor 42 turns on / off the upper arm elements UH, VH, WH and the lower arm elements UL, VL, and WL of the first power conversion circuit unit (drive circuit DT) and the second power conversion circuit unit 32, respectively. The voltage fluctuation generated by the switching operation of is smoothed. The second smoothing capacitor 42 is used for on / off switching operation of the upper arm element S1 (switching element 11A) and the lower arm element S2 (switching element 11A) at the time of boosting the voltage of the third power conversion circuit unit (voltage conversion unit 11). Smooths out the voltage fluctuations that accompany it.

The noise filter 43 is provided between the positive electrode side conductor PI and the negative electrode side conductor NI of the first power conversion circuit unit (drive circuit DT) and the second power conversion circuit unit 32, and the third power conversion circuit unit (voltage conversion). It is connected between the positive electrode bus bar PV and the negative electrode bus bar NV of the part 11). The noise filter 43 includes two capacitors connected in series. The connection points of the two capacitors are connected to the body ground of the vehicle 10 and the like.
The resistor 24 is provided between the positive electrode side conductor PI and the negative electrode side conductor NI of the first power conversion circuit unit (drive circuit DT) and the second power conversion circuit unit 32, and the third power conversion circuit unit (voltage conversion). It is connected between the positive electrode bus bar PV and the negative electrode bus bar NV of the part 11).

The first current sensor 25 forms a connection point TI of each phase of the first power conversion circuit unit (drive circuit DT), is arranged on the output side conductor 51 connected to the first input / output terminal Q1, and is U-phase. , V phase, and W phase currents are detected. The second current sensor 26 forms a connection point TI of each phase of the second power conversion circuit unit 32 and is arranged on the output side conductor 52 connected to the second input / output terminal Q2, and is arranged in the U phase, the V phase, and the U phase. Each current in the W phase is detected. The third current sensor 27 forms a connection point between the upper arm element S1 (switching element 11A) and the lower arm element S2 (switching element 11A), and is arranged on the bus bar 53 connected to the reactor 22 to transmit the current flowing through the reactor 22. To detect.
Each of the first current sensor 25, the second current sensor 26, and the third current sensor 27 is connected to the electronic control unit 28 by a signal line.

The electronic control unit 28 controls the operation of each of the first motor (load LD) and the second motor 13. For example, the electronic control unit 28 is a software function unit that functions by executing a predetermined program by a processor such as a CPU (Central Processing Unit). The software function unit is an ECU (Electronic Control Unit) equipped with a processor such as a CPU, a ROM (Read Only Memory) for storing programs, a RAM (Random Access Memory) for temporarily storing data, and an electronic circuit such as a timer. is there. At least a part of the electronic control unit 28 may be an integrated circuit such as an LSI (Large Scale Integration). For example, the electronic control unit 28 executes current feedback control or the like using the current detection value of the first current sensor 25 and the current target value according to the torque command value for the first motor (load LD), and executes the gate drive unit ( A control signal to be input to the control device 12) is generated. For example, the electronic control unit 28 executes current feedback control or the like using the current detection value of the second current sensor 26 and the current target value corresponding to the regeneration command value for the second motor 13, and the gate drive unit (control device 12). ) To generate a control signal. The control signal turns on (conducting) / off each of the upper arm elements UH, VH, WH and the lower arm elements UL, VL, and WL of the first power conversion circuit unit (drive circuit DT) and the second power conversion circuit unit 32. (Interruption) This is a signal indicating the timing of driving. For example, the control signal is a pulse width modulated signal or the like.

The gate drive unit (control device 12) has upper arm elements UH, VH, WH and the first power conversion circuit unit (drive circuit DT) and the second power conversion circuit unit 32 based on the control signal received from the electronic control unit 28. A gate signal for actually driving each of the lower arm elements UL, VL, and WL on (conducting) / off (cutting off) is generated. For example, the gate drive unit (control device 12) executes amplification of a control signal, level shift, and the like to generate a gate signal.
The gate drive unit (control device 12) turns on (conducts) / off each of the upper arm element S1 (switching element 11A) and the lower arm element S2 (switching element 11A) of the third power conversion circuit unit (voltage conversion unit 11). (Interruption) Generates a gate signal for driving. For example, the gate drive unit (control device 12) has a boost voltage command at the time of boosting the third power conversion circuit unit (voltage conversion unit 11) or a step-down voltage command at the time of regeneration of the third power conversion circuit unit (voltage conversion unit 11). Generates a gate signal with a duty ratio according to. The duty ratio is the ratio of the upper arm element S1 (switching element 11A) and the lower arm element S2 (switching element 11A).

FIG. 6 shows the upper arm elements UH, VH, WH (switching element DTS for the drive circuit) and the lower arm elements UL, VL, WL (drive circuit) of the first power conversion circuit unit (drive circuit DT) in the vehicle 10 shown in FIG. It is a figure which shows the relationship between the drive frequency (switching frequency) of the switching element DTS) and efficiency.
In detail, FIG. 6 shows the relationship between the drive frequency (switching frequency) of the drive circuit switching element DTS and the efficiency when the drive circuit switching element DTS of the drive circuit DT is formed of a wide bandgap semiconductor. There is.
In FIG. 6, "PDU efficiency" indicates the efficiency of the first power conversion circuit unit (drive circuit DT), "motor efficiency" indicates the efficiency of the first motor (load LD), and "total efficiency". Shows the efficiency of the entire vehicle 10 shown in FIG.
As shown in FIG. 6, when the drive circuit switching element DTS is formed of a wide bandgap semiconductor, even if the drive frequency of the drive circuit DT of the first motor (load LD) becomes high, "PDU efficiency" is obtained. (Efficiency of the drive circuit DT of the first motor (load LD)) does not decrease significantly. Further, the higher the drive frequency of the drive circuit DT of the first motor (load LD), the higher the "motor efficiency". Therefore, even if the drive frequency of the drive circuit DT of the first motor (load LD) is increased, the "total efficiency" does not change significantly.

FIG. 7 is a diagram showing an example of a method of connecting power electronics components in a vehicle in recent years.
In FIG. 7, “HBAT” indicates a high voltage battery and indicates a power electronics component corresponding to the power supply PS in FIG. “DC-DC” indicates a power electronics component corresponding to the third power conversion circuit unit (voltage conversion unit 11) in FIG. “AC” indicates a power electronics component corresponding to the first motor (load LD) and the second motor 13 in FIG. The “PCU” is a first power conversion circuit unit (drive circuit) arranged between the third power conversion circuit unit (voltage conversion unit 11) in FIG. 5 and the first motor (load LD) and the second motor 13. DT) and the power electronics component corresponding to the second power conversion circuit unit 32 are shown. “External power supply” refers to a power electronics component that receives power from a power source PS (HBAT) and is not shown in FIG. 5 (for example, an auxiliary machine).
In modern vehicles, in order to avoid resonance between interconnected power electronics components, for example, input capacitance, input resistance, internal resistance, internal inductance, wiring resistance, wiring inductance, single current ripple width, etc. By investigating the parameters of each power electronics component and adjusting the capacitor capacity, cable length, etc. of each power electronics component, resonance between the power electronics components is finally avoided.
If a hardware component as a resonance avoidance means is added in order to reduce the complexity of the work of avoiding this resonance, the overall cost will increase.
In order to solve this problem, by applying the power conversion device 1 of the first or second embodiment to the vehicle 10 shown in FIG. 5, for example, the plurality of power electronics described above can be suppressed while suppressing the overall cost. Resonance between components can be suppressed.

For example, in the vehicle 10 as shown in FIG. 5, as the switching frequency of the switching element (for example, upper arm element UH, VH, WH, S1, lower arm element UL, VL, WL, S2, etc.) becomes higher, for example, the first 1 As the capacitance of the smoothing capacitor 41 and the inductance of the reactor 22 become smaller, the switching frequency of the drive circuit switching element DTS of the drive circuit DT and the resonance frequency of the power converter 1 in the direct connection operation mode of the power converter 1 Is easier to match. Therefore, the area in which the efficient direct connection operation mode can be executed is narrowing.
Therefore, as described above, in the power conversion device 1 of the first or second embodiment, the switching frequency of the drive circuit switching element DTS of the drive circuit DT becomes a high frequency fA when the power conversion device 1 operates in the direct connection mode. It is set and deviated from the resonance frequencies RfA and RfB corresponding to the resonance points A and B. Further, since the direct connection operation mode is carried out in a state where the drive power is relatively low, there is no problem with the heat of the device such as the switching element DTS for the drive circuit of the drive circuit DT.
When the power conversion device 1 of the first or second embodiment is applied to a vehicle 10 as shown in FIG. 5, for example, a hardware component as a resonance avoidance means is provided even if the loss is slightly increased. It is considered to be more advantageous than when it is added.

The embodiments of the present invention are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, as well as in the scope of the invention described in the claims and the equivalent scope thereof.

1 ... Power conversion device, 11 ... Voltage conversion unit, 11A ... Switching element, 12 ... Control device, PS ... Power supply, LD ... Load, DT ... Drive circuit, DTS ... Switching element for drive circuit

Claims (8)

A voltage converter that converts the voltage of the power supplied from the power supply and outputs it to the drive circuit of the load.
A control device that controls the drive circuit and the voltage conversion unit, and
In a power converter equipped with
The voltage conversion unit includes a switching element controlled by the control device.
The control device is
The first control of stopping the switching operation of the switching element of the voltage conversion unit and directly applying the voltage of the power supply to the drive circuit, and
The voltage conversion unit performs a second control of converting the voltage of the power supply into a voltage and applying it to the drive circuit.
A power conversion device characterized in that the drive frequency of the drive circuit when performing the first control is changed from the drive frequency of the drive circuit when performing the second control. The drive frequency of the drive circuit when performing the first control is set to be higher than the drive frequency of the drive circuit when performing the second control.
The power conversion device according to claim 1. The drive frequency of the drive circuit when the drive power of the drive circuit is smaller than the threshold value is made higher than the drive frequency of the drive circuit when the drive power of the drive circuit is equal to or more than the threshold value.
The power conversion device according to claim 1. The drive frequency of the drive circuit when performing the first control is set to be higher than the resonance frequency of the power converter when performing the first control, and the power when performing the second control. Make it higher than the resonance frequency of the converter,
The power conversion device according to claim 2. The drive frequency of the drive circuit when performing the second control is set to be higher than the resonance frequency of the power converter when performing the first control, and the power when performing the second control. Lower than the resonance frequency of the converter,
The power conversion device according to claim 4. The control device performs a first determination of whether to perform the first control or the second control, and a second determination of whether or not the operating state of the power conversion device is included in the resonance region. And do
The control device is
When the first control is performed and the operating state of the power conversion device is included in the resonance region,
The drive frequency of the drive circuit when performing the second control is changed to the drive frequency of the drive circuit when performing the first control.
The power conversion device according to claim 1. The control device is
When the second control is performed, or when the operating state of the power conversion device is not included in the resonance region.
Maintaining the drive frequency of the drive circuit when performing the second control,
The power conversion device according to claim 6. The drive circuit includes a switching element for the drive circuit.
The drive circuit switching element is formed of a wide bandgap semiconductor.
The power conversion device according to any one of claims 1 to 7.

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