Device for controlling power conversion circuit

Abstract

Provided is a device for controlling a power conversion circuit, said device making it possible to suppress any deterioration in performance for tracking a second voltage at a transition time when a second current of a second terminal changes at a frequency lower than the resonance frequency of the power conversion circuit while suppressing any vibration of a control system at the resonance frequency. This device for controlling a power conversion circuit: calculates a first control value so that a detection value for a second voltage approaches a target value for the second voltage; calculates a pre-filter second control value by multiplying a detection value for a reactor current by an attenuation gain; calculates a second control value by performing, on the pre-filter second control value, a filter process for passing a pass frequency band that includes the resonance frequency of the power conversion circuit; calculates a control value on the basis of the first control value and the second control value; and controls the turning on and turning off of a switching element on the basis of the control value.

Description

Power conversion circuit control device

[0001] The present disclosure relates to a control device for a power conversion circuit.

[0002] In Patent Document 1, a first control value is calculated by performing feedback control so that the detected value of the second voltage at the second terminal approaches a target value of the second voltage. The second control value is also calculated by multiplying the reactor current by an attenuation gain. The second control value is then subtracted from the first control value to calculate a control value, and the switching elements of the power conversion circuit are controlled to be turned on and off based on the control value. The second control value suppresses vibrations in the control system at the resonant frequency of the power conversion circuit.

[0003] Patent No. 6153144

[0004] In the technology of Patent Document 1, the second control value reduces the gain at the resonant frequency in the frequency characteristics of the gain of the second voltage with respect to the second current at the second terminal, thereby suppressing vibration. However, because a value according to the reactor current is subtracted from the first control value, the gain of the second voltage with respect to the second current increases at frequencies lower than the resonant frequency. This deteriorates the tracking performance of the second voltage during transient changes in the second current.

[0005] In addition, by increasing the capacitance of the smoothing capacitor on the second terminal side, it is possible to suppress fluctuations in the second voltage when the second current changes and reduce the withstand voltage of the element; however, this increases the size of the power conversion circuit, so improvement through control is desired.

[0006] Therefore, the present disclosure aims to provide a control device for a power conversion circuit that can suppress vibrations in the control system at the resonant frequency of the power conversion circuit, while suppressing deterioration in the tracking performance of the second voltage during transients when the second current of the second terminal changes at frequencies lower than the resonant frequency.

[0007] a second voltage detection unit configured to detect a second voltage which is a voltage on the high potential side relative to the low potential side of the second terminal; a reactor current detection unit configured to detect a reactor current flowing through the reactor; a second voltage control unit configured to calculate a first control value such that the detected value of the second voltage approaches a target value of the second voltage; a damping control unit configured to calculate a second control value based on the detected value of the reactor current; a control value calculation unit configured to calculate a control value based on the first control value and the second control value; and a switching control unit configured to control on / off of the one or more switching elements based on the control value. The damping control unit multiplies the detected value of the reactor current by a damping gain to calculate a second control value before filtering, and performs filtering on the second control value before filtering to pass a pass frequency band that includes the resonant frequency of the power conversion circuit, thereby calculating the second control value.

[0008] According to the control device for a power conversion circuit according to the present disclosure, by performing a filter process that passes a pass frequency band including the resonant frequency on the second control value before filtering, which is obtained by multiplying the detected value of the reactor current by the attenuation gain, it is possible to suppress an increase in the gain of the second voltage with respect to the second current at frequencies lower than the resonant frequency while maintaining the vibration suppression effect of the control system near the resonant frequency obtained by the multiplication process by the attenuation gain, and to suppress deterioration in the tracking performance of the detected value of the second voltage with respect to the target value of the second voltage during a transient period in which the second current changes. Furthermore, since the control accuracy of the second voltage can be improved, it is possible to lower the withstand voltage of elements in the power conversion circuit, thereby reducing the weight of the power conversion circuit.

[0009] 1 is a schematic configuration diagram of a power conversion circuit and a control device according to embodiment 1. FIG. 2 is a block diagram of the control device according to embodiment 1. FIG. 3 is a hardware configuration diagram of the control device according to embodiment 1. FIG. 4 is a diagram showing frequency characteristics of the gain of the second voltage with respect to the second current for each control method according to embodiment 1. FIG. 5 is a time chart explaining the difference in tracking ability of the second voltage depending on whether or not filter processing is performed when the second current fluctuates according to embodiment 1. FIG. 6 is a time chart explaining on / off control of a switching element according to embodiment 1. FIG. 7 is a block diagram of a control device according to embodiment 2. FIG. 8 is a schematic configuration diagram of a power conversion circuit and a control device according to embodiment 3.

[0010] 1. First Embodiment A power conversion circuit 10 and a control device 30 for the power conversion circuit (hereinafter simply referred to as the control device 30) according to a first embodiment will be described with reference to the drawings. Fig. 1 is a schematic diagram of the power conversion circuit 10 and the control device 30 according to the present embodiment.

[0011] 1-1. Power Conversion Circuit 10 The power conversion circuit 10 has one or more switching elements and a reactor 15, and performs power conversion between a first terminal 11 and a second terminal 12. The first terminal 11 is composed of a high-potential terminal 11a and a low-potential terminal 11b. The second terminal 12 is composed of a high-potential terminal 12a and a low-potential terminal 12b. A DC power supply or a load is connected to the first terminal 11, and a DC power supply or a load is connected to the second terminal 12. In this embodiment, a DC power supply 21 is connected to the first terminal 11, and a load 22 is connected to the second terminal 12.

[0012] In this embodiment, the power conversion circuit 10 is a DC-DC converter that converts DC power. The power conversion circuit 10 is a step-up chopper circuit that boosts a DC voltage from a first terminal 11 to a second terminal 12. The power conversion circuit 10 also functions as a step-down chopper circuit that drops a DC voltage from the second terminal 12 to the first terminal 11. That is, the power conversion circuit 10 is a bidirectional chopper circuit.

[0013] The power conversion circuit 10 has a semiconductor circuit section 20 having one or more switching elements connected between the high potential side 12a and low potential side 12b of the second terminal 12, and a reactor 15 having one end connected to the high potential side 11a of the first terminal and the other end connected to the semiconductor circuit section 20, and the low potential side 11b of the first terminal and the low potential side 12b of the second terminal are connected, and power conversion is performed between the first terminal 11 and the second terminal 12.

[0014] The semiconductor circuit unit 20 has two switching elements 13a and 13b connected in series between the high potential side 12a and the low potential side 12b of the second terminal 12. The other end of the reactor 15 is connected to the connection point between the two switching elements 13a and 13b.

[0015] The switching elements may be IGBTs (Insulated Gate Bipolar Transistors) with anti-parallel diodes, or MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) with the function of anti-parallel diodes. Alternatively, various switching elements such as SiC (Silicon Carbide)-MOSFETs, GaN (Gallium Nitride)-FETs, and GaN-HEMTs (High Electron Mobility Transistors) may be used.

[0016] Gate drive signals Gt1 and Gt2 output from the control device 30 are input to the gate terminals of the switching elements 13a and 13b, respectively, and the switching elements 13a and 13b are turned on and off in accordance with the gate drive signals Gt1 and Gt2.

[0017] A smoothing capacitor 16 on the second terminal side is connected between the high potential side 12a and the low potential side 12b of the second terminal. The smoothing capacitor 16 on the second terminal side is connected closer to the second terminal 12 than the two switching elements 13a, 13b (semiconductor circuit unit 20). A smoothing capacitor 17 on the first terminal side is connected between the high potential side 11a and the low potential side 11b of the first terminal. The smoothing capacitor 17 on the first terminal side is connected closer to the first terminal 11 than the reactor 15.

[0018] The inverter is provided with a second voltage detection circuit 18 that detects a second voltage V2sen, which is the voltage on the high potential side 12a of the second terminal relative to the low potential side 12b. In this embodiment, the second voltage detection circuit 18 detects the voltage across the smoothing capacitor 16 on the second terminal side. An output signal from the second voltage detection circuit 18 is input to the control device 30.

[0019] The inverter is provided with a reactor current sensor 14 that detects a reactor current ILsen flowing through the reactor 15. The reactor current sensor 14 is provided on an electric wire connecting the high potential side 11a of the first terminal and the reactor 15. The reactor current sensor 14 is a Hall element, a shunt resistor, or the like. An output signal of the reactor current sensor 14 is input to the control device 30.

[0020] 1-2. Control Device 30 The control device 30 controls the power conversion circuit 10. As shown in FIG. 2 , the control device 30 includes a second voltage detection unit 31, a reactor current detection unit 32, a second voltage control unit 33, a damping control unit 34, a control value calculation unit 35, and a switching control unit 36. Each function of the control device 30 is realized by a processing circuit included in the control device 30. Specifically, as shown in FIG. 3 , the control device 30 includes, as processing circuits, an arithmetic processing device 90 (computer) such as a CPU (Central Processing Unit), a storage device 91 connected to the arithmetic processing device 90 via a signal line such as a bus, an input circuit 92 that inputs external signals to the arithmetic processing device 90, and an output circuit 93 that outputs signals from the arithmetic processing device 90 to the outside.

[0021] The arithmetic processing device 90 may be an ASIC (Application Specific Integrated Circuit), an IC (Integrated Circuit), a DSP (Digital Signal Processor), an FPGA (Field Programmable Gate Array), various logic circuits, various signal processing circuits, etc. Furthermore, a plurality of the same or different types of arithmetic processing device 90 may be provided, and each process may be shared and executed.

[0022] The storage device 91 includes volatile and non-volatile storage devices such as RAM (Random Access Memory), ROM (Read Only Memory), and EEPROM (Electrically Erasable Programmable ROM). The input circuit 92 is connected to various sensors such as the second voltage detection circuit 18 and the reactor current sensor 14, and includes an A / D converter and the like that inputs output signals from these sensors to the arithmetic processing device 90. The output circuit 93 is connected to electrical loads such as a gate drive circuit that drives switching elements on and off, and includes a drive circuit and the like that outputs control signals from the arithmetic processing device 90 to these electrical loads.

[0023] The functions of the control units 31 to 36 of the control device 30 are realized by the arithmetic processing device 90 executing software (programs) stored in a storage device 91 such as a ROM, and working in cooperation with other hardware of the control device 30 such as the storage device 91, an input circuit 92, and an output circuit 93. Setting data such as control gains used by the control units 31 to 36 is stored in the storage device 91 such as a ROM as part of the software (programs). Each function of the control device 30 will be described in detail below.

[0024] 1-2-1. Second Voltage Detector 31 The second voltage detector 31 detects the second voltage V2sen, which is the voltage at the second terminal 12. In this embodiment, the second voltage detector 31 detects the second voltage V2sen based on the output signal of the second voltage detector circuit 18.

[0025] 1-2-2 Reactor Current Detector 32 The reactor current detector 32 detects the reactor current ILsen flowing through the reactor. The reactor current detector 32 detects the reactor current ILsen based on the output signal of the reactor current sensor 14.

[0026] 1-2-3. Second Voltage Control Unit 33 The second voltage control unit 33 calculates a first control value X1 such that the detected value V2sen of the second voltage approaches the target value V2ref of the second voltage. In this embodiment, the second voltage control unit 33 changes the first control value X1 through feedback control so that the detected value V2sen of the second voltage approaches the target value V2ref of the second voltage. As the feedback control, the second voltage control unit 33 performs at least proportional control and integral control based on the deviation ΔV2 between the detected value V2sen of the second voltage and the target value V2ref of the second voltage. In this embodiment, proportional control and integral control, i.e., PI control, are performed. Note that differential control, i.e., PID control, may be performed in addition to proportional control and integral control. The target value V2ref of the second voltage may be calculated within the control device 30 or may be transmitted from outside the control device 30.

[0027] Specifically, as shown in the following equation, the second voltage control unit 33 calculates a deviation ΔV2 by subtracting the detected value V2sen of the second voltage from the target value V2ref of the second voltage, calculates a first proportional control value X1p by multiplying the deviation ΔV2 by a proportional gain Kp, calculates a first integral control value X1i by integrating the product of the deviation ΔV2 and the integral gain Ki, and calculates the first integral control value X1i by adding the first proportional control value X1p and the first integral control value X1i. In equation (1), s is a Laplace operator, and 1 / s represents an integral operation.

[0028] 1-2-4. Damping Control Unit 34 The damping control unit 34 calculates the second control value X2 based on the reactor current detection value ILsen. As shown in the following equation, the damping control unit 34 multiplies the reactor current detection value ILsen by the attenuation gain Kdp to calculate the pre-filtered second control value X2bf, and then performs filtering on the pre-filtered second control value X2bf to pass a pass frequency band including the resonant frequency fr of the power conversion circuit, thereby calculating the second control value X2. Note that the pass frequency band is set to a frequency band greater than frequency 0, and at least the DC component is attenuated by the filtering.

[0029] Here, Gflt(s) is a transfer function representing the filtering process. In this embodiment, as will be described later, the control value D is calculated by subtracting the second control value X2 from the first control value X1, so the attenuation gain Kdp is set to a positive value. Note that when the control value D is calculated by adding the second control value X2 to the first control value X1, the attenuation gain Kdp is set to a negative value.

[0030] The reactor current detection value ILsen to be multiplied by the attenuation gain Kdp may be the reactor current detection value ILsen detected in the previous calculation cycle, or a value obtained by performing a smoothing process such as low-pass filtering or moving average processing on the reactor current detection value ILsen to attenuate the oscillation component of the PWM control cycle.

[0031] 4 shows frequency characteristics of the gain of the second voltage V2 with respect to the second current I2 flowing from the second terminal 12 to the load 22. In Fig. 4, the solid line shows the frequency characteristics when the multiplication process by the attenuation gain Kdp of the damping control unit 34 and the filtering process are not performed and only the feedback control of the second voltage control unit 33 is performed, the dashed line shows the frequency characteristics when the multiplication process by the attenuation gain Kdp of the damping control unit 34 is performed but the filtering process is not performed and the feedback control of the second voltage control unit 33 is performed, and the dashed line shows the frequency characteristics when the multiplication process by the attenuation gain Kdp of the damping control unit 34 and the filtering process are performed and the feedback control of the second voltage control unit 33 is performed.

[0032] When only feedback control is performed without multiplication by the attenuation gain Kdp or filtering, the gain near the resonance frequency fr increases, causing the second voltage V2 to change oscillatorily with changes in the resonance frequency fr component of the second current I2. When multiplication by the attenuation gain Kdp is performed but filtering is not performed, the gain near the resonance frequency fr can be reduced, but the gain at frequencies lower than the resonance frequency fr increases in an offset manner, resulting in poor tracking performance during transient response. When multiplication by the attenuation gain Kdp and filtering are performed, the gain near the resonance frequency fr can be reduced, and filtering suppresses the offset increase in gain at frequencies lower than the resonance frequency fr. This is because filtering passes components in the pass frequency band including the resonance frequency fr, which are included in the second control value X2 of the second voltage control unit 33, thereby reducing the gain near the resonance frequency fr and attenuating pass frequency components lower than the pass frequency band including the resonance frequency fr, thereby approaching a state where the second voltage control unit 33 is not controlling the second voltage control unit 33.

[0033] FIG. 5 shows the control behavior of the second voltage V2 when the second current I2 changes. The change in the second current I2 occurs due to, for example, a change in the power consumption of the load 22 connected to the second terminal 12. In FIG. 5, the solid line indicates a case where feedback control is performed without multiplication by the attenuation gain Kdp but without filtering, and the dashed line indicates a case where feedback control is performed with multiplication by the attenuation gain Kdp and filtering. When filtering is not performed, the tracking performance of the detected value V2sen of the second voltage relative to the target value V2ref of the second voltage deteriorates due to an increase in the gain of the frequency characteristics in a transient state where the second current I2 is changing. On the other hand, when filtering is performed, the increase in the gain of the frequency characteristics is suppressed in a transient state where the second current I2 is changing, so the tracking performance of the detected value V2sen of the second voltage relative to the target value V2ref of the second voltage is maintained favorably. Therefore, by performing a filtering process on the pre-filtered second control value X2bf, which is obtained by multiplying the reactor current detection value ILsen by the attenuation gain Kdp, and passing a pass band of frequencies including the resonance frequency fr, it is possible to suppress an increase in the gain of the second voltage V2 with respect to the second current I2 at frequencies lower than the resonance frequency fr while maintaining the vibration suppression effect of the control system near the resonance frequency fr obtained by the multiplication process by the attenuation gain Kdp, and to suppress deterioration in the tracking performance of the second voltage detection value V2sen with respect to the second voltage target value V2ref during transient changes in the second current I2. Furthermore, since the control accuracy of the second voltage V2 can be improved, it is possible to lower the withstand voltage of the elements of the power conversion circuit 10, and thereby reduce the weight of the power conversion circuit 10.

[0034] <Filtering> The damping control unit 34 uses high-pass filtering or band-pass filtering as filtering. Various known filtering methods can be used for high-pass filtering or band-pass filtering. When high-pass filtering is used, the cutoff frequency of the high-pass filtering is set to a frequency lower than the resonance frequency band, and the pass frequency band is a frequency band equal to or higher than the cutoff frequency. The resonance frequency band is a frequency band including the resonance frequency fr where the gain of the frequency characteristic becomes greater than 0 due to resonance. When band-pass filtering is used, the pass frequency band is set to a frequency band including the resonance frequency band. Note that the pass frequency band is set to a frequency band greater than 0, and at least the DC component is attenuated by filtering.

[0035] <Setting of Resonance Frequency fr> The damping control unit 34 calculates the resonance frequency fr based on a control value D, which will be described later, and sets a pass frequency band based on the resonance frequency fr.

[0036] The damping control unit 34 calculates the resonance frequency fr based on the control value D using the following equation.

[0037] Here, L is the inductance of the reactor 15, and a preset value is used. C2 is the capacitance of the smoothing capacitor 16 on the second terminal side, and a preset value is used. As will be described later, the control value D is the on-duty ratio of the low-potential side switching element 13b. If the control value D is not the on-duty ratio of the low-potential side switching element 13b, the on-duty ratio of the low-potential side switching element 13b may be used instead of the control value D.

[0038] Alternatively, the damping control unit 34 may calculate the resonance frequency fr based on the first voltage V1 and the second voltage V2. As shown in the following equation, the damping control unit 34 calculates a control value equivalent value Deq based on the first voltage V1 and the second voltage V2, and calculates the resonance frequency fr based on the control value equivalent value Deq. In this case, the control value equivalent value Deq is used instead of the control value D in equation (3), and the resonance frequency fr is calculated.

[0039] Here, the second voltage V2 is a detected value V2sen of the second voltage or a target value V2ref of the second voltage. Also, the first voltage V1 may be a preset value, or a voltage sensor may be provided to detect the first voltage V1 and the detected value V1sen of the first voltage may be used.

[0040] When high-pass filtering is used, the pass frequency band is set to a frequency band equal to or higher than a cutoff frequency obtained by subtracting a preset offset value from the calculated resonance frequency fr. When band-pass filtering is used, the pass frequency band is set to a frequency band ranging from a lower limit frequency obtained by subtracting a lower limit offset value from the resonance frequency fr to an upper limit frequency obtained by adding an upper limit offset value to the calculated resonance frequency fr.

[0041] 1-2-5. Control Value Calculation Unit 35 The control value calculation unit 35 calculates the control value D based on the first control value X1 and the second control value X2. In this embodiment, as shown in the following equation, the control value calculation unit 35 calculates the control value D by subtracting the second control value X2 from the first control value X1. Note that the control value calculation unit 35 may also calculate the control value D by adding the second control value X2 to the first control value X1. In this case, as described above, the attenuation gain Kdp is set to a negative value.

[0042] 1-2-6. Switching Control Unit 36 ​​The switching control unit 36 ​​controls the on / off of one or more switching elements based on the control value D.

[0043] The switching control unit 36 ​​generates gate drive signals Gt1 and Gt2 for the high-side and low-side switching elements 13a and 13b, respectively, by PWM (Pulse Width Modulation) control based on a control value D. In this embodiment, the control value D represents the on-duty ratio of the low-side switching element 13b and the off-duty ratio of the high-side switching element 13a. When the low-side switching element 13b is on, the high-side switching element 13a is off. To prevent the two switching elements 13a and 13b from being on simultaneously and short-circuiting the high-side and low-side switching elements, a dead time is provided between the on-period of the high-side switching element 13a and the on-period of the low-side switching element 13b, during which both are off.

[0044] For example, as shown in FIG. 6 , the switching control unit 36 ​​compares the control value D with the carrier wave Vcr and generates gate drive signals Gt1 and Gt2 for each switching element. The carrier wave Vcr is a triangular wave that oscillates between 0 and 1 at a PWM control period. When the control value D is greater than the carrier wave Vcr, the switching control unit 36 ​​sets the low-potential gate drive signal Gt2 to High. When the control value D is smaller than the carrier wave Vcr, the switching control unit 36 ​​sets the low-potential gate drive signal Gt2 to Low. Furthermore, when the control value D+ΔDt, which is obtained by adding a value ΔDt corresponding to the dead time to the control value D, is greater than the carrier wave Vcr, the switching control unit 36 ​​sets the high-potential gate drive signal Gt1 to Low. When the control value D+ΔDt after addition is smaller than the carrier wave Vcr, the switching control unit 36 ​​sets the high-potential gate drive signal Gt1 to High. A sawtooth wave or an inverted sawtooth wave may be used as the carrier wave Vcr.

[0045] 2. Second Embodiment Next, a power conversion circuit 10 and a control device 30 according to a second embodiment will be described with reference to the drawings. Description of components similar to those of the first embodiment will be omitted. The basic configuration and processing of the power conversion circuit 10 and the control device 30 according to this embodiment are similar to those of the first embodiment, but the method of setting the resonant frequency fr differs from that of the first embodiment. Figure 7 shows a block diagram of the control device 30 according to this embodiment.

[0046] In the present embodiment, the damping control unit 34 performs frequency analysis on the detected value ILsen of the reactor current to detect the resonant frequency fr, and sets the pass frequency band based on the resonant frequency fr. The detected value V2sen of the second voltage may be used instead of the detected value ILsen of the reactor current.

[0047] According to this configuration, the pass frequency band is set based on the actually detected resonant frequency fr. Therefore, even if the resonant frequency fr fluctuates due to variations or fluctuations in the inductance L of the reactor 15 or the capacitance C2 of the smoothing capacitor 16 on the second terminal side, the resonant frequency fr can be detected and the pass frequency band can be set with high accuracy.

[0048] For example, the damping control unit 34 performs a discrete Fourier transform (DFT) on the reactor current detection value ILsen (or the second voltage detection value V2sen) to determine the frequency at which the intensity is high. Then, the damping control unit 34 excludes all frequencies other than the PWM control frequency and a frequency band that may be a preset resonant frequency from the multiple frequencies at which the intensity is high, and determines the frequency at which the intensity is highest as the resonant frequency fr. Then, as in the first embodiment, the damping control unit 34 sets the pass frequency band based on the resonant frequency fr.

[0049] Alternatively, the damping control unit 34 extracts vibration components other than the PWM control frequency from the waveform of the reactor current detection value ILsen (or the second voltage detection value V2sen), and calculates the reciprocal of the period of the vibration components as the resonance frequency fr. Then, as in the first embodiment, the damping control unit 34 sets the pass frequency band based on the resonance frequency fr.

[0050] 3. Third Embodiment Next, a power conversion circuit 10 and a control device 30 according to a third embodiment will be described with reference to the drawings. Description of components similar to those of the first or second embodiment will be omitted. The basic configuration and processing of the power conversion circuit 10 and the control device 30 according to this embodiment are similar to those of the first or second embodiment, but differ from the first or second embodiment in that the load 22 at the second terminal 12 is specified as an inverter that supplies power to a rotating electric machine.

[0051] As shown in FIG. 8 , an inverter 112 that supplies power to a rotating electric machine 113 is connected to the second terminal 12. For example, the rotating electric machine 113 is used as a driving force source for wheels of a vehicle. The rotating electric machine 113 has a multi-phase (three-phase in this example) armature winding. The inverter 112 converts DC power supplied from the second terminal 12 into AC power and supplies it to the armature windings of each phase. Note that multiple inverters may be connected to the second terminal 12, or a converter that supplies AC power to the field winding may be connected. Furthermore, the rotating electric machine 113 may perform one or both of power running and power generation. When the rotating electric machine 113 generates power, the power conversion circuit 10 steps down the generated power supplied to the second terminal 12 and supplies it to the first terminal 11.

[0052] The DC power supplied from the second terminal 12 to the inverter 112 varies depending on the output torque and rotation speed of the rotating electric machine 113. Therefore, the second current I2 supplied from the second terminal 12 to the inverter 112 varies depending on the output torque and rotation speed of the rotating electric machine 113. The output torque and rotation speed of the rotating electric machine 113 vary greatly depending on the running state of the vehicle, and the second current I2 also varies greatly.

[0053] As described in the first embodiment, by performing a filter process that passes a pass band including the resonant frequency fr, the vibration suppression effect of the control system near the resonant frequency fr, achieved by the multiplication process using the damping gain Kdp, is maintained. This suppresses an increase in the gain of the second voltage V2 relative to the second current I2 at frequencies other than the pass band. This suppresses a deterioration in the tracking performance of the detected value V2sen of the second voltage relative to the target value V2ref of the second voltage during a transient state in which the second current I2 changes. This improves the control accuracy of the second voltage V2 supplied to the inverter 112, thereby improving the control accuracy of the rotating electric machine and the control accuracy of the vehicle's driving force. Furthermore, since the control accuracy of the second voltage V2 can be improved, the withstand voltage of the elements of the power conversion circuit 10 can be reduced, thereby reducing the weight of the power conversion circuit 10 and the vehicle. Furthermore, since the tracking performance of the second voltage V2 can be maintained even when the change rates of the second voltage V2 and the second current I2 are increased, the change rate of the output torque of the rotating electric machine can be increased, improving the responsiveness of the output torque of the rotating electric machine and the acceleration / deceleration performance of the vehicle.

[0054] Other Embodiments (1) In the above-described embodiments, the power conversion circuit 10 is described as a bidirectional chopper circuit that combines a boost chopper circuit that boosts a DC voltage from the first terminal 11 to the second terminal 12 and a step-down chopper circuit that steps down a DC voltage from the second terminal 12 to the first terminal 11. However, the power conversion circuit 10 may operate only as a step-up chopper circuit. In this case, a diode may be used instead of the high-potential side switching element 13a. Alternatively, the power conversion circuit 10 may operate only as a step-down chopper circuit. In this case, a diode may be used instead of the low-potential side switching element 13b.

[0055] (2) In the above-described embodiments, the DC power supply 21 is connected to the first terminal 11, and the load 22 is connected to the second terminal 12. However, it is sufficient that a DC power supply or a load is connected to the first terminal 11, and a DC power supply or a load is connected to the second terminal 12. Various types of DC power supplies and loads may be used for the DC power supply and the load.

[0056] (3) In the above embodiments, the control device 30 calculates the first control value X1 based on the target value V2ref and the detected value V2sen of the second voltage. However, the control device 30 may calculate the first control value X1 using a target value and a detected value of other electrical information related to the power conversion circuit 10. For example, the control device 30 may use the voltage, current, or power input to or output from the first terminal 11 or the second terminal 12 as the electrical information. Furthermore, the control device 30 may use, as the electrical information, a value obtained by performing low-pass filtering or moving average smoothing on the voltage, current, or power input to or output from the first terminal 11 or the second terminal 12.

[0057] (4) In the above-described embodiments, the semiconductor circuit unit 20 of the power conversion circuit 10 has two switching elements 13a, 13b connected in series between the high potential side 12a and the low potential side 12b of the second terminal 12. However, in the semiconductor circuit unit 20, two or more switching elements may be connected in series or in parallel as an upper arm, which is a portion on the higher potential side than the connection portion with the reactor 15, and two or more switching elements may be connected in series or in parallel as a lower arm, which is a portion on the higher potential side than the connection portion with the reactor 15.

[0058] Although various exemplary embodiments and examples are described in this disclosure, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are contemplated within the scope of the technology disclosed in this disclosure specification. For example, this includes cases where at least one component is modified, added, or omitted, or where at least one component is extracted and combined with components of another embodiment.

[0059] 10: power conversion circuit, 11: first terminal, 11a: high potential side of first terminal, 11b: low potential side of first terminal, 12: second terminal, 12a: high potential side of second terminal, 12b: low potential side of second terminal, 15: reactor, 20: semiconductor circuit unit, 30: control device of power conversion circuit, 33: second voltage control unit, 34: damping control unit, 35: control value calculation unit, 36: switching control unit, ILsen: detected value of reactor current, Kdp: attenuation gain, V2ref: target value of second voltage, V2sen: detected value of second voltage, X1: first control value, X2: second control value, X2bf: second control value before filtering, fr: resonance frequency, D: control value

Claims

1. A control device for a power conversion circuit that controls a power conversion circuit having a semiconductor circuit section having one or more switching elements connected between the high-potential side and the low-potential side of a second terminal, and a reactor having one end connected to the high-potential side of a first terminal and the other end connected to the semiconductor circuit section, wherein the low-potential side of the first terminal and the low-potential side of the second terminal are connected, and the power conversion circuit that performs power conversion between the first terminal and the second terminal, A second voltage detection unit detects a second voltage which is the voltage on the high potential side relative to the low potential side of the second terminal, A reactor current detection unit for detecting the reactor current flowing through the reactor, A second voltage control unit calculates a first control value such that the detected value of the second voltage approaches the target value of the second voltage, A damping control unit calculates a second control value based on the detected value of the reactor current, A control value calculation unit that calculates a control value based on the first control value and the second control value, The system includes a switching control unit that controls the on / off state of one or more of the switching elements based on the control value, The damping control unit is a control device for a power conversion circuit that calculates a second control value before filtering by multiplying the detected value of the reactor current by a damping gain, and then performs a filtering process on the second control value before filtering to pass through a pass frequency band that includes the resonant frequency of the power conversion circuit, thereby calculating the second control value.

2. The control device for a power conversion circuit according to claim 1, wherein the damping control unit calculates the resonant frequency based on the first voltage and the second voltage, which are the voltages on the high potential side relative to the low potential side of the first terminal, or the control value, and sets the pass frequency band based on the resonant frequency.

3. The control device for a power conversion circuit according to claim 1, wherein the damping control unit performs frequency analysis on the detected value of the reactor current or the detected value of the second voltage to detect the resonant frequency and sets the pass frequency band based on the resonant frequency.

4. The control device for a power conversion circuit according to any one of claims 1 to 3, wherein the damping control unit uses high-pass filtering or band-pass filtering as the filtering process.

5. A control device for a power conversion circuit according to any one of claims 1 to 3, wherein a DC power supply is connected to the first terminal and an inverter for supplying power to a rotating electric machine is connected to the second terminal.