Power converter control device, program, and power converter control method

Abstract

A power converter (40, 70, 100, 140, 240) is configured to be able to execute switching control to pass a current through reactors (55a, 55b) so as to transmit power from an input-side circuit, which is one of a primary-side circuit (51) and a secondary-side circuit (52), to an output-side circuit, which is the other. A control device (16) for the power converter comprises: an input-side signal generation unit (16a) that generates, on the basis of a command value of a current flowing through a reactor, an input-side drive signal for executing switching control, the input-side drive signal being a drive signal for the input-side circuit; an output-side signal generation unit (16b) that generates, on the basis of the generated input-side drive signal, an output-side drive signal that allows the current of the reactor to flow in a direction in which power is transmitted from the output-side circuit to the input-side circuit, the output-side drive signal being a drive signal for the output-side circuit; and a control unit (16c) that performs switching control on the basis of the generated input-side drive signal and output-side drive signal.

Description

Control device, program, and method for controlling a power converter CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Japanese Application No. 2024-121304, filed on July 26, 2024, the contents of which are incorporated herein by reference.

[0002] The present disclosure relates to a control device for a power converter, a program, and a control method for a power converter.

[0003] Conventionally, a power converter applied to a system including a chargeable and dischargeable power storage unit has been known. The power converter has a primary side circuit and a secondary side circuit capable of transmitting power between them. A primary side terminal pair of the primary side circuit is connected in parallel to the power storage unit. A secondary side terminal pair of the secondary side circuit is connected in series to the power storage unit. A control device of the power converter performs switching control to transmit power from either the primary side circuit or the secondary side circuit to the other.

[0004] For example, the control device performs switching control so that the shortfall in the output voltage of the power storage unit out of the voltage required by the system is output from the secondary terminal pair of the power converter. This reduces the rated voltage of the power converter, thereby achieving a smaller capacity of the power converter. An example of such a technology is the technology disclosed in Patent Document 1.

[0005] Japanese Patent Application Laid-Open No. 2022-23722

[0006] In a power converter having a reactor, switching control may be performed to pass a current through the reactor so as to transmit power from one of an input side circuit (a primary side circuit) and a secondary side circuit (an output side circuit). In this case, the current mode of the power converter may switch from one of a continuous current mode and a discontinuous current mode to the other. The continuous current mode is a current mode in which a current continues to flow through the reactor during one switching cycle of the switching control. The discontinuous current mode is a current mode in which the current flowing through the reactor is zero during a portion of one switching cycle of the switching control.

[0007] The current response of the power converter differs depending on whether the current mode of the power converter is continuous current mode or discontinuous current mode. Therefore, for example, during a period when the charge / discharge of the energy storage unit is switched, the current response may change as the current mode of the power converter switches, potentially reducing the controllability of the current flowing through the reactor. This raises concerns about system malfunctions, such as unintended current flowing through the reactor or excessive voltage being applied to the secondary terminal pair.

[0008] An object of the present disclosure is to provide a control device, a program, and a method for controlling a power converter that can suppress the occurrence of system malfunctions.

[0009] The present disclosure relates to a power converter control device that is applied to a system including a chargeable and dischargeable power storage unit, and a power converter having a primary side circuit and a secondary side circuit, wherein the primary side circuit has a primary side terminal pair connected in parallel to the power storage unit, the secondary side circuit has a secondary side terminal pair connected in series to the power storage unit, the primary side circuit and the secondary side circuit have a switch and a rectifying element connected in anti-parallel to the switch, the power converter has a reactor and is configured to be able to perform switching control of the switch that causes a current to flow in the reactor so as to transmit power from an input side circuit that is one of the primary side circuit and the secondary side circuit to an output side circuit that is the other of the primary side circuit and the secondary side circuit, an input side signal generation unit that generates an input side drive signal for executing the switching control, which is a drive signal for the switch in the input side circuit based on a command value of the current flowing in the reactor, an output-side signal generating unit that generates, based on the input-side drive signal generated by the input-side signal generating unit, a drive signal for the switch in the output-side circuit, the output-side drive signal allowing a current in the reactor to flow in a direction in which power is transmitted from the output-side circuit to the input-side circuit; and a control unit that performs the switching control based on the input-side drive signal generated by the input-side signal generating unit and the output-side drive signal generated by the output-side signal generating unit.

[0010] In the above-described system, switching control for transmitting power from the input circuit to the output circuit is performed based on an input drive signal for a switch in the input circuit. In this case, the rectifying element in the output circuit is conductive, and current flows through the reactor in the direction in which power is transmitted from the input circuit to the output circuit. When the current flow direction of the reactor is constant during one switching period, the power converter operates in continuous current mode.

[0011] In the present disclosure, an output drive signal for a switch included in an output circuit is generated based on the input drive signal generated by the input signal generating unit, and the output drive signal is a drive signal that allows a current to flow through a reactor in a direction in which power is transmitted from the output circuit to the input circuit.

[0012] By performing switching control based on the generated input drive signal and output drive signal, the current flow direction of the reactor is allowed to be reversed within one switching period, and the current mode of the power converter is prevented from entering discontinuous current mode. Therefore, for example, during a period when the charge / discharge of the power storage unit is switched, changes in the current response of the power converter can be suppressed, and the controllability of the current flowing through the reactor can be improved. As a result, the occurrence of system malfunctions can be prevented.

[0013] The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.1 is a configuration diagram of a power conversion system according to a first embodiment, FIG. 2 is a diagram showing an example of a power converter, FIG. 3 is a time chart for explaining a step-down operation, FIG. 4 is a time chart for explaining a step-up operation, FIG. 5 is a functional block diagram showing control performed by a control device, FIG. 6 is a diagram showing the relationship between the current of a storage battery and a switching control amount, FIG. 7 is a time chart for explaining a resonance phenomenon that occurs in a discontinuous current mode, and FIG. 8 is a time chart showing an example of a step-down operation. 9 is a diagram showing a current path in a first period, FIG. 10 is a diagram showing a current path in a second period, FIG. 11 is a diagram showing a current path in a third period, FIG. 12 is a diagram showing a current path in a fourth period, FIG. 13 is a diagram showing a current path in a fifth period, FIG. 14 is a diagram showing a current path in a sixth period, FIG. 15 is a diagram showing a current path in a seventh period, FIG. 16 is a diagram showing a current path in an eighth period, FIG. 17 is a time chart showing an example of a boost operation, and FIG. 18 is a diagram showing a current path in the first and 21 is a diagram showing a current path in the fourth and eighth periods, FIG. 22 is a diagram showing a current path in the sixth period, FIG. 23 is a diagram showing a current path in the seventh period, FIG. 24 is a diagram showing the relationship between the current of the storage battery and the switching control amount, FIG. 25 is a diagram for explaining the power conversion efficiency in switching control, and FIG. 26 is a diagram showing the control performed by the control device. FIG. 27 is a flowchart showing a processing procedure, FIG. 28 is a time chart showing an example of a step-down operation, FIG. 29 is a time chart showing an example of a step-up operation, FIG. 30 is a configuration diagram of a power conversion system according to a second embodiment, FIG. 31 is a diagram showing an example of a power converter, FIG. 32 is a diagram showing an example of a power converter, FIG. 33 is a diagram showing an example of a power converter, and FIG. 34 is a configuration diagram of a power conversion system according to another embodiment.

[0014] Several embodiments will be described with reference to the drawings. In several embodiments, functionally and / or structurally corresponding and / or associated parts may be designated by the same reference numerals or reference numerals that differ in the hundredth or more digit. For corresponding and / or associated parts, reference may be made to the descriptions of other embodiments.

[0015] A first embodiment of a control device according to the present disclosure will now be described with reference to the drawings. In this embodiment, the control device constitutes a power conversion system mounted on an electrically powered vehicle such as an electric vehicle or a hybrid vehicle.

[0016] FIG. 1 shows a configuration diagram of a power conversion system 10. The power conversion system 10 includes a storage battery module 30. The storage battery module 30 includes a storage battery 31 (corresponding to a "power storage unit"). The storage battery 31 is, for example, a battery pack configured as a series connection of battery cells serving as single cells. The battery cells may be, for example, rechargeable secondary batteries such as lithium ion batteries.

[0017] A load 21 is electrically connected to a high-potential side terminal 11 and a low-potential side terminal 12 of the power conversion system 10. The high-potential side terminal 11 is electrically connected to a positive electrode side of a storage battery module 30 via a high-potential side path 13 such as a bus bar. The low-potential side terminal 12 is electrically connected to a negative electrode side of the storage battery module 30 via a low-potential side path 14 such as a bus bar. As a result, the storage battery module 30 is electrically connected in parallel to the load 21. The high-potential side terminal 11 and the low-potential side terminal 12 correspond to an "external terminal pair."

[0018] Specifically, the load 21 is a three-phase inverter 22 and a rotating electric machine 23. The rotating electric machine 23 has armature windings electrically connected to the inverter 22, the number of which corresponds to the number of phases. The inverter 22 controls the current flowing through the windings of each phase. The rotating electric machine 23 is an on-board main engine, and a rotor of the rotating electric machine 23 is capable of transmitting power to the drive wheels of the vehicle. The rotating electric machine 23 is, for example, a permanent magnet synchronous machine.

[0019] The high-potential side path 13 is electrically connected to the positive electrode side of the inverter 22, and the low-potential side path 14 is electrically connected to the negative electrode side of the inverter 22. This enables current to flow between the power conversion system 10 and the load 21. The inverter 22 converts DC power supplied from the power conversion system 10 into AC power and supplies the power to each phase winding of the rotating electric machine 23. In this case, the rotating electric machine 23 serves as a power source for running the vehicle. The rotating electric machine 23 also generates regenerative power using rotational force applied to the rotor. The inverter 22 converts the generated AC power into DC power and outputs it to the power conversion system 10.

[0020] The storage battery module 30 includes a power converter 40. The power converter 40 is electrically connected to the storage battery 31 and the load 21. Specifically, the power converter 40 includes a primary-side terminal pair consisting of a primary-side positive terminal 41 and a primary-side negative terminal 42, and a secondary-side terminal pair consisting of a secondary-side positive terminal 43 and a secondary-side negative terminal 44. The primary-side positive terminal 41 is electrically connected to the positive side of the storage battery 31. The primary-side negative terminal 42 and the negative side of the storage battery 31 are electrically connected to the inverter 22 via the low-potential-side path 14. In other words, the primary-side terminal pair of the power converter 40 is electrically connected in parallel to the storage battery 31. In this case, the voltage of the storage battery 31 is applied to the primary-side terminal pair of the power converter 40.

[0021] The secondary negative terminal 44 is electrically connected to the positive electrode side of the storage battery 31. The secondary positive terminal 43 of the power converter 40 is electrically connected to the inverter 22 via the high potential side path 13. In other words, the secondary terminal pair of the power converter 40 is electrically connected in series to the storage battery 31 on the positive electrode side of the storage battery 31.

[0022] The secondary-side terminal voltage VLr applied to the secondary-side terminal pair of the power converter 40 is the difference voltage between the voltage between each path 13, 14 (specifically, the voltage supplied to the inverter 22) and the voltage Vbat of the storage battery 31. The secondary-side terminal voltage VLr is lower than the primary-side terminal voltage VHr applied to the primary-side terminal pair. For this reason, the secondary-side rated voltage on the secondary side of the power converter 40 is set to be lower than the rated voltage of the storage battery 31 (e.g., 400 V), e.g., 16 V. This allows the power converter 40 to be made smaller.

[0023] 2 shows an example of a power converter 40. The power converter 40 is an isolated DC-DC converter and includes a transformer 50, a primary circuit 51, a secondary circuit 52, a primary capacitor 53, and a secondary capacitor 54.

[0024] The transformer 50 includes a primary winding 50a and a secondary winding 50b. The primary winding 50a and the secondary winding 50b are wound around a common core. As a result, the primary winding 50a and the secondary winding 50b are magnetically coupled by the common core. For example, the ratio of the number of turns N1 of the primary winding 50a to the number of turns N2 of the secondary winding 50b is N1:N2=7:1.

[0025] The primary circuit 51 is a full-bridge circuit and includes a first switch S1, a second switch S2, a third switch S3, and a fourth switch S4 as primary switches, and a primary reactor 55a. In this embodiment, the first to fourth switches S1 to S4 are voltage-controlled semiconductor switching elements, more specifically, N-channel MOSFETs. In this case, the high-potential terminal of each switch S1 to S4 is the drain, and the low-potential terminal is the source. The first, second, third, and fourth switches S1, S2, S3, and S4 each have body diodes D1, D2, D3, and D4.

[0026] The drain of the first switch S1 and the drain of the third switch S3 are electrically connected to the primary-side positive terminal 41 and the first end of the primary-side capacitor 53. The source of the first switch S1 is electrically connected to the drain of the second switch S2. The source of the third switch S3 is electrically connected to the drain of the fourth switch S4. The source of the second switch S2 and the source of the fourth switch S4 are electrically connected to the primary-side negative terminal 42 and the second end of the primary-side capacitor 53.

[0027] A first end of the primary winding 50a is electrically connected to a first end of the primary reactor 55a. A second end of the primary reactor 55a is electrically connected to a source of the first switch S1 and a drain of the second switch S2. A second end of the primary winding 50a is electrically connected to a source of the third switch S3 and a drain of the fourth switch S4. The first to fourth switches S1 to S4 are controlled by a control device 16 included in the power conversion system 10.

[0028] The secondary-side circuit 52 is a center-tap circuit and includes a fifth switch S5 and a sixth switch S6 as secondary-side switches, and a secondary-side reactor 55b. In this embodiment, the fifth and sixth switches S5 and S6 are voltage-controlled semiconductor switching elements, more specifically, N-channel MOSFETs. The fifth and sixth switches S5 and S6 also have body diodes D5 and D6. The body diodes D1 to D6 of the switches S1 to S6 correspond to "rectifying elements."

[0029] The secondary winding 50b has a center tap. The center tap of the secondary winding 50b is electrically connected to a first end of a secondary reactor 55b. A second end of the secondary reactor 55b is electrically connected to the secondary positive terminal 43 and a first end of the secondary capacitor 54. The first end of the secondary winding 50b is electrically connected to the drain of a fifth switch S5. The second end of the secondary winding 50b is electrically connected to the drain of a sixth switch S6. The sources of the fifth and sixth switches S5 and S6 are electrically connected to the secondary negative terminal 44 and the second end of the secondary capacitor 54.

[0030] Returning to the explanation of Fig. 1, the power conversion system 10 includes a battery monitoring device 32. For example, the battery monitoring device 32 detects the terminal voltage, current, internal resistance, SOC, etc. of each battery cell constituting the storage battery 31, and monitors the state of the storage battery 31. The detected values ​​detected by the battery monitoring device 32 are input to the control device 16.

[0031] The power conversion system 10 includes a voltage sensor 45 and a current sensor 46. The voltage sensor 45 detects a primary-side terminal voltage VHr applied to a primary-side terminal pair of the power converter 40 and a secondary-side terminal voltage VLr applied to a secondary-side terminal pair of the power converter 40. The current sensor 46 detects a secondary-side current Ior flowing through the secondary side of the power converter 40. The detected values ​​of the sensors 45, 46 are input to the control device 16.

[0032] For example, the voltage sensor 45 and the current sensor 46 are arranged in the power converter 40 as shown in FIG. 2 . The voltage sensors 45 include a primary-side voltage sensor 45a and a secondary-side voltage sensor 45b. The primary-side voltage sensor 45a detects the voltage of the primary-side capacitor 53 as a primary-side terminal voltage VHr. The secondary-side voltage sensor 45b detects the voltage of the secondary-side capacitor 54 as a secondary-side terminal voltage VLr. The polarity of each voltage VHr, VLr is positive when the potential at the first terminal of each capacitor 53, 54 is higher than the second terminal. The polarity is negative when the potential at the second terminal of each capacitor 53, 54 is higher than the first terminal. The current sensor 46 detects the current flowing through the secondary-side reactor 55b as a secondary-side current Ior. The sign of the secondary current Ior is positive when the current flows from the first terminal to the second terminal of the secondary reactor 55b, and negative when the current flows from the second terminal to the first terminal of the secondary reactor 55b.

[0033] The control device 16 is an electronic control unit (ECU) that performs various controls of the power conversion system 10 and includes a processor and a storage unit as hardware. In the control device 16, the processor and storage unit are connected to each other via a communication bus. In the power conversion system 10, each on-board device can be controlled by its corresponding ECU. However, for convenience, multiple ECUs are shown as a single control device 16 in FIG. 1 .

[0034] The memory unit of the control device 16 includes a memory and a storage as hardware. The memory is a storage device for storing data used in the processing of the control device 16. The memory provides the processor with a working area for temporary use when the processor performs processing, for example. The memory includes, for example, a ROM or a RAM. The storage is a storage device for storing various programs and data to be read and executed by the processor, and is a non-transitory tangible storage medium. The storage includes, for example, an HDD or a flash memory. The storage stores program information and the like for processing, such as those shown in Figures 5, 26, and 27, which will be described later.

[0035] For example, program information stored in a non-transient physical recording medium is installed in the storage unit of the control device 16. The recording medium is, for example, a USB memory, a CD-ROM, or a DVD. Also, for example, program information transmitted via a communication network, such as over the air (OTA), is installed in the storage unit.

[0036] In this embodiment, the control device 16 controls the switching of each switch S1 to S6 so as to control the average value of the secondary-side current Ior in one switching period Ts to the secondary-side command current Io*. The secondary-side command current Io* is a command value for the secondary-side current Ior and is set as a time average value in one switching period Ts. Specifically, the control device 16 sets the secondary-side command current Io* to a positive value and performs switching control. In this case, a step-down operation is performed to transfer power from the primary-side circuit 51 to the secondary-side circuit 52. During the step-down operation of the power converter 40, the power discharged from the storage battery 31 is controlled. Furthermore, the control device 16 sets the secondary-side command current Io* to a negative value and performs switching control. In this case, a step-up operation is performed to transfer power from the secondary-side circuit 52 to the primary-side circuit 51. During the step-up operation of the power converter 40, the power charged to the storage battery 31 is controlled.

[0037] An example of the step-down operation is shown in Fig. 3. In Fig. 3, (a) shows the transition of the secondary current Ior, (b) shows the transition of the voltage VR of the secondary reactor 55b, (c) shows the on / off state of the first switch S1, and (d) shows the on / off state of the third switch S3. The sign of the voltage VR of the secondary reactor 55b is positive when the potential of the first terminal is higher than that of the second terminal, and negative when the potential of the second terminal is higher than that of the first terminal. The second switch S2 is controlled so that the on / off state of the first switch S1 is reversed. The fourth switch S4 is controlled so that the on / off state of the third switch S3 is reversed.

[0038] When the power converter 40 performs a step-down operation, the control device 16 controls the switching of the first to fourth switches S1 to S4. Specifically, the control device 16 turns the first switch S1 on and off so that the duty ratio of the first switch S1 is 50%, and turns the third switch S3 on and off so that the duty ratio of the third switch S3 is 50%. The duty ratios of the first and third switches S1 and S3 are the ratios of the on-periods of the first switch S1 in one switching period Ts. During the step-down operation, the control device 16 controls the phase shift amount θd as a switching control amount. The phase shift amount θd is a value determined, for example, based on the difference between the on-timing of the first switch S1 and the on-timing of the third switch S3 in one switching period Ts. The control device 16 fixes the fifth and sixth switches S5 and S6 to the off state, for example, in one switching period Ts.

[0039] An example of the voltage boosting operation is shown in Fig. 4. In Fig. 4, (a) and (b) correspond to Fig. 3(a) and (b), (c) shows the on / off state of the fifth switch S5, and (d) shows the on / off state of the sixth switch S6.

[0040] When the power converter 40 performs a boost operation, the control device 16 controls the switching of the fifth and sixth switches S5 and S6. Specifically, the control device 16 turns the fifth and sixth switches S5 and S6 on and off with a duty ratio Dd of 50% or more. The duty ratio Dd of the fifth and sixth switches S5 and S6 is the ratio of the on-period of the fifth and sixth switches S5 and S6 in one switching period Ts. During the boost operation, the control device 16 controls the duty ratio Dd as a switching control variable, more specifically, the duty increase amount Dα. The duty increase amount Dα is the amount by which the duty ratio of the fifth and sixth switches S5 and S6 exceeds 50% and corresponds to the period during one switching period Ts during which both the fifth and sixth switches S5 and S6 are on. Note that the control device 16 fixes the first to fourth switches S1 to S4 to the off state, for example, for one switching period Ts.

[0041] As shown in Figures 3 and 4, the step-down operation and the step-up operation are divided into two current modes depending on the state of the secondary-side current Ior. The first current mode is a continuous current mode in which the secondary-side current Ior continues to flow during one switching period Ts. The second current mode is a discontinuous current mode in which the secondary-side current Ior becomes zero during a portion of one switching period Ts. Figure 3 shows various waveforms in the step-down operation for both the continuous current mode and the discontinuous current mode. Figure 4 shows various waveforms in the step-up operation for both the continuous current mode and the discontinuous current mode. The continuous current mode is also referred to as CCM. The discontinuous current mode is also referred to as DCM.

[0042] Next, a description will be given of the configuration for performing switching control of the power converter 40. Fig. 5 shows a functional block diagram of the switching control executed by the control device 16. First, a description will be given assuming that the power converter 40 performs a voltage boost operation.

[0043] The control device 16 includes an input signal generating unit 16 a, an output signal generating unit 16 b, and a switching control unit 16 c. In this embodiment, the input signal generating unit 16 a includes, as components for performing feedback control, a voltage deviation calculating unit 17 a, a voltage feedback control unit 17 b, a current deviation calculating unit 17 c, and a current feedback control unit 17 d.

[0044] The voltage deviation calculation unit 17a acquires the secondary-side terminal voltage VLr and the secondary-side command voltage VL*. For example, the secondary-side terminal voltage VLr can be a detected value of the secondary-side voltage sensor 45b. For example, the secondary-side command voltage VL* can be a value set by a higher-level control device for the control device 16. The voltage deviation calculation unit 17a calculates a voltage deviation ΔV, which is the difference between the acquired secondary-side command voltage VL* and the secondary-side terminal voltage VLr.

[0045] The voltage deviation ΔV calculated by the voltage deviation calculation unit 17 a is input to the voltage feedback control unit 17 b, which calculates a secondary-side command current Io* as a manipulated variable for feedback control of the input voltage deviation ΔV to zero.

[0046] The current deviation calculation unit 17c receives the secondary-side command current Io* calculated by the voltage feedback control unit 17b and the secondary-side current Ior. For example, the secondary-side current Ior can be a detected value of the current sensor 46. The current deviation calculation unit 17c calculates a current deviation ΔI, which is the difference between the acquired secondary-side command current Io* and the secondary-side current Ior.

[0047] The current deviation ΔI calculated by the current deviation calculation unit 17c is input to the current feedback control unit 17d. The current feedback control unit 17d calculates a feedback control amount Dfb as a manipulated variable for feedback-controlling the input current deviation ΔI to 0. The feedback control amount Dfb is a feedback term of the duty ratio Dd of the fifth and sixth switches S5 and S6.

[0048] The input signal generator 16a includes a corrector 17e as a component for performing feedforward control. The corrector 17e calculates a correction amount Dff used to correct the feedback control amount Dfb. The correction amount Dff is a feedforward term of the duty ratio Dd of the fifth and sixth switches S5 and S6. The feedforward control is performed to improve the controllability of the secondary current Ior.

[0049] Specifically, the correction unit 17e includes a correction amount calculation unit 18a, a minimum value selection unit 18b, and an adder 18c. The correction amount calculation unit 18a acquires a primary-side terminal voltage VHr, a secondary-side terminal voltage VLr, a secondary-side current Ior, and a secondary-side command current Io*. The primary-side terminal voltage VHr can be a detected value from the primary-side voltage sensor 45a. The correction amount calculation unit 18a calculates a first correction amount Dt1 and a second correction amount Dt2 based on the acquired terminal voltages VHr, VLr, and secondary-side command current Io*. The first correction amount Dt1 is a correction amount calculated assuming that the current mode in the boost operation is a continuous current mode. For example, the correction amount calculation unit 18a calculates the first correction amount Dt1 based on the number of turns N1 of the primary winding 50a, the number of turns N2 of the secondary winding 50b, the primary terminal voltage VHr, the secondary terminal voltage VLr, and the following equation (eq1):

[0050] The second correction amount Dt2 is calculated assuming that the current mode in the boost operation is a discontinuous current mode. For example, the correction amount calculator 18a calculates the second correction amount Dt2 based on the number of turns N1 of the primary winding 50a, the number of turns N2 of the secondary winding 50b, the primary terminal voltage VHr, the secondary terminal voltage VLr, the assumed inductance Ls of each reactor 55a, 55b, the secondary command current Io*, the length Ts of one switching period, and the following equation (eq2):

[0051] The minimum value selector 18b receives the first correction amount Dt1 and the second correction amount Dt2 calculated by the correction amount calculator 18a and selects the smaller of the input first correction amount Dt1 and the input second correction amount Dt2 as the correction amount Dff.

[0052] The adder 18c receives the feedback control amount Dfb calculated by the current feedback control unit 17d and the correction amount Dff selected by the minimum value selection unit 18b, and calculates the sum of the feedback control amount Dfb and the correction amount Dff as the duty ratio Dd of the fifth and sixth switches S5 and S6.

[0053] The input signal generating section 16a includes a modulating section 17f that generates drive signals for the fifth and sixth switches S5 and S6 based on the duty ratio Dd.

[0054] Specifically, the modulator 17f includes a carrier signal generator 19a and a comparator 19b. The carrier signal generator 19a generates a carrier signal Sc used for PWM control. For example, the carrier signal Sc is a sawtooth wave signal.

[0055] The comparator 19b receives the duty ratio Dd calculated by the adder 18c and the carrier signal Sc generated by the carrier signal generator 19a. The comparator 19b is, for example, a comparator. The comparator 19b generates drive signals for the fifth and sixth switches S5 and S6 based on a magnitude comparison between the input duty ratio Dd and the carrier signal Sc. The drive signals are ON or OFF commands.

[0056] The output signal generating unit 16b generates drive signals for the first to fourth switches S1 to S4. For example, the output signal generating unit 16b generates drive signals that fix the first to fourth switches S1 to S4 to OFF during one switching period Ts. The processing performed by the output signal generating unit 16b will be described later.

[0057] The switching control unit 16c receives drive signals for the fifth and sixth switches S5 and S6 generated by the comparison unit 19b and drive signals for the first to fourth switches S1 to S4 generated by the output signal generation unit 16b. The switching control unit 16c controls the charge / discharge currents of the gates of the first to sixth switches S1 to S6 based on the drive signals for the fifth and sixth switches S5 and S6 input thereto. This controls the on / off of the first to sixth switches S1 to S6 in accordance with the drive signals.

[0058] Next, the configuration for controlling the switching of the power converter 40 will be described assuming a step-down operation. In this case, the input signal generator 16a generates drive signals for the first to fourth switches S1 to S4. The output signal generator 16b generates drive signals for the fifth and sixth switches S5 and S6.

[0059] The current feedback control unit 17d calculates a feedback control amount θfb, which is a feedback term of the phase shift amount θd, instead of the feedback control amount Dfb, which is a feedback term of the duty ratio Dd.

[0060] The corrector 17e calculates a correction amount θff, which is a feedforward term of the phase shift amount θd, instead of the correction amount Dff, which is a feedforward term of the duty ratio Dd. Specifically, the correction amount calculator 18a calculates first and second correction amounts θ1 and θ2 for the phase shift amount θd based on the acquired terminal voltages VHr and VLr and secondary command current Io*. For example, the correction amount calculator 18a calculates the first correction amount θ1 based on the number of turns N1 of the primary winding 50a, the number of turns N2 of the secondary winding 50b, the primary terminal voltage VHr, the secondary terminal voltage VLr, and the following equation (eq3):

[0061] For example, the correction amount calculation unit 18a calculates the second correction amount θ2 based on the number of turns N1 of the primary winding 50a, the number of turns N2 of the secondary winding 50b, the primary terminal voltage VHr, the secondary terminal voltage VLr, the assumed inductance Ls of each reactor 55a, 55b, the secondary command current Io*, the length Ts of one switching period, and the following equation (eq4):

[0062] The first correction amount θ1 and the second correction amount θ2 calculated by the correction amount calculation unit 18a are input to the minimum value selection unit 18b, which selects the smaller of the input first correction amount θ1 and the second correction amount θ2 as the correction amount θff.

[0063] The adder 18c receives the feedback control amount θfb calculated by the current feedback control unit 17d and the correction amount θff selected by the minimum value selection unit 18b. The adder 18c calculates the sum of the feedback control amount θfb and the correction amount θff as the phase shift amount θd of the first to fourth switches S1 to S4. The modulator 17f receives the phase shift amount θd calculated by the adder 18c. The modulator 17f generates drive signals for the first to fourth switches S1 to S4 based on the input phase shift amount θd.

[0064] The output signal generating unit 16b generates drive signals for the fifth and sixth switches S5 and S6. For example, the output signal generating unit 16b generates drive signals that fix the fifth and sixth switches S5 and S6 to the off state during one switching period Ts. The processing performed by the output signal generating unit 16b will be described later.

[0065] The current response of the power converter 40 differs between the continuous current mode and the discontinuous current mode. Therefore, for example, during a period when the storage battery 31 switches between charging and discharging, the current response of the power converter 40 changes as the current mode of the power converter 40 switches, potentially reducing the controllability of the secondary-side current Ior. In this case, there is a concern that a malfunction of the power conversion system 10 may occur. For example, there is a concern that an unintended current may flow through the reactors 55a and 55b, or that an excessive voltage may be applied to the secondary-side terminal pair. Furthermore, there is a concern that, for example, the secondary-side capacitor 54 may be enlarged to prevent an excessive voltage from being applied to the secondary-side terminal pair, limiting the ability to reduce the capacity of the power converter 40.

[0066] For example, as shown in FIG. 6 , in the step-down operation region where the step-down operation of the power converter 40 is performed, the current mode is set to continuous current mode in the region where the current Ibat (specifically, the discharge current) of the storage battery 31 is greater than the predetermined discharge value Id. In the step-down operation region where the current Ibat of the storage battery 31 is smaller than the predetermined discharge value Id, the current mode is set to discontinuous current mode. Furthermore, in the step-up operation region where the step-up operation of the power converter 40 is performed, the current mode is set to continuous current mode in the region where the current Ibat (specifically, the charge current) of the storage battery 31 is greater than the predetermined charge value Ic. In the step-up operation region where the current Ibat of the storage battery 31 is smaller than the predetermined charge value Ic, the current mode is set to discontinuous current mode. Therefore, when the state of the storage battery 31 switches from one of the discharge state and the charge state to the other, the current mode of the power converter 40 may switch from continuous current mode to discontinuous current mode to continuous current mode.

[0067] The predetermined discharge value Id and the predetermined charge value Ic are values ​​determined according to the relationship between the ripple amplitude of the secondary current Ior and the current Ibat of the storage battery 31. For example, the predetermined discharge value Id is determined according to the ripple amplitude of the secondary current Ior (see FIG. 3 ) that is a positive value in one switching period Ts. Specifically, the predetermined discharge value Id is determined as half the difference between the maximum and minimum values ​​of the secondary current Ior that is a positive value. Furthermore, for example, the predetermined charge value Ic is determined according to the ripple amplitude of the secondary current Ior (see FIG. 4 ) that is a negative value in one switching period Ts. Specifically, the predetermined charge value Ic is determined as half the difference between the maximum and minimum values ​​of the secondary current Ior that is a negative value.

[0068] In each of the step-down operation region and the step-up operation region, the current responsiveness of the power converter 40 differs between the continuous current mode and the discontinuous current mode. Specifically, in the step-down operation region, the discontinuous current mode has a smaller current change rate, which is the slope of the current Ibat of the storage battery 31 with respect to a change in the phase shift amount θd, than the continuous current mode. In the step-up operation region, the discontinuous current mode has a smaller current change rate, which is the slope of the current Ibat of the storage battery 31 with respect to a change in the duty ratio Dd, than the continuous current mode.

[0069] Here, the point that the current change rate in discontinuous current mode is smaller than the current change rate in continuous current mode will be explained using a case where voltage step-up operation is performed as an example. Fig. 7 is a diagram showing an example of voltage step-up operation in discontinuous current mode. In Fig. 7, (a) shows the transition of the secondary current Ior, (b) shows the on / off of the fifth switch S5, (c) shows the on / off of the sixth switch S6, and (d) shows the on / off of the first to fourth switches S1 to S4.

[0070] In FIG. 7 , the first to fourth switches S1 to S4 are fixed to off during one switching period Ts. In this case, a blocking period Tp occurs during one switching period Ts. The blocking period Tp is a period during which the flow of a positive secondary current Ior is blocked. The direction in which the secondary current Ior is positive is the direction in which power is transmitted from the primary circuit 51 to the secondary circuit 52. During the blocking period Tp, a voltage corresponding to the voltage across the primary terminal pairs is applied to the parasitic capacitance of the first to fourth switches S1 to S4, causing a resonance phenomenon between the inductance of the primary reactor 55a and the parasitic capacitance of the first to fourth switches S1 to S4. Due to the effect of the resonance phenomenon, distortion occurs in the secondary current Ior during the blocking period Tp. In a discontinuous current mode in which an unintended current flows during the blocking period Tp, the time average value of the actual secondary current Ior may deviate from the secondary command current Io*. As a result, the rate of change of current in the discontinuous current mode is smaller than that in the continuous current mode. Note that it is difficult to estimate the current that flows due to the occurrence of the resonance phenomenon, and even if feedforward control is performed in calculating the duty ratio Dd of the fifth and sixth switches S5 and S6, there is a possibility that the time average value of the actual secondary current Ior will deviate from the secondary command current Io*.

[0071] Therefore, in this embodiment, the output signal generating unit 16b receives the input drive signal generated by the input signal generating unit 16a. Based on the input drive signal, the output signal generating unit 16b generates an output drive signal that drives a switch in the output circuit. Specifically, the output signal generating unit 16b generates a drive signal that allows the secondary current Ior to flow in the direction of power transmission from the output circuit to the input circuit. The output drive signal is generated in this manner to turn on the switch in the output circuit in accordance with the flow state of the secondary current Ior and prevent the current mode of the power converter 40 from becoming a discontinuous current mode. This is because the flow state of the secondary current Ior is considered to be determined by the drive state of the switch in the input circuit.

[0072] During voltage step-down operation, the primary side circuit 51 is the input side circuit, and the secondary side circuit 52 is the output side circuit. In this case, the drive signals of the first to fourth switches S1 to S4 are input side drive signals, and the drive signals of the fifth and sixth switches S5 and S6 are output side drive signals. During voltage step-up operation, the secondary side circuit 52 is the input side circuit, and the primary side circuit 51 is the output side circuit. In this case, the drive signals of the fifth and sixth switches S5 and S6 are input side drive signals, and the drive signals of the first to fourth switches S1 to S4 are output side drive signals.

[0073] The switching control unit 16c performs switching control based on the input drive signal generated by the input signal generation unit 16a and the output drive signal generated by the output signal generation unit 16b. The switching control for preventing the power converter 40 from entering the discontinuous current mode will be described in detail below. First, the step-down operation of the power converter 40 will be described.

[0074] The output signal generating unit 16b generates drive signals for the fifth and sixth switches S5 and S6 based on the drive signals for the first to fourth switches S1 to S4 generated by the input signal generating unit 16a. In this embodiment, the output signal generating unit 16b generates a synchronization signal synchronized with the drive signal for the first switch S1 as the drive signal for the sixth switch S6. The output signal generating unit 16b generates a synchronization signal synchronized with the drive signal for the second switch S2 as the drive signal for the fifth switch S5. More specifically, the drive signal for the fifth switch S5 has the same on and off commands as the drive signal for the first switch S1. The drive signal for the sixth switch S6 has the same on and off commands as the drive signal for the second switch S2.

[0075] 8 shows an example of switching control for suppressing the discontinuous current mode during voltage step-down operation. In FIG. 8, (a) shows the transition of the secondary current Ior, (b) shows the on / off state of the first switch S1, (c) shows the on / off state of the third switch S3, (d) shows the on / off state of the sixth switch S6, and (e) shows the on / off state of the fifth switch S5. The second switch S2 is controlled to a state in which the on / off state of the first switch S1 is reversed. The fourth switch S4 is controlled to a state in which the on / off state of the third switch S3 is reversed.

[0076] 9 to 16 show the paths of current flowing through the power converter 40 during periods TA1 to TA8 of one switching cycle TA. The parasitic capacitances of the switches S1 to S6 are also shown in FIGS. 9 to 16. Hereinafter, when the potential of the first end of the primary winding 50a and the secondary winding 50b is higher than the potential of the second end, the polarity of the voltage of each winding 50a, 50b is assumed to be positive. When the potential of the second end of the primary winding 50a, 50b is higher than the potential of the second end, the polarity of the voltage of each winding 50a, 50b is assumed to be negative.

[0077] Of the periods TA1 to TA8, in the third period TA3, the fourth period TA4, the seventh period TA7, and the eighth period TA8, the secondary current Ior is allowed to flow in the direction of power transmission from the secondary circuit 52 to the primary circuit 51. The path of the current flowing through the power converter 40 in each of the periods TA1 to TA8 will be described in detail below.

[0078] During the first period TA1, the first, fourth, and sixth switches S1, S4, and S6 are turned on, and the second, third, and fifth switches S2, S3, and S5 are turned off. In this case, as shown in FIG. 9 , in the primary circuit 51, current flows in the following order: primary positive terminal 41, first switch S1, primary reactor 55a, primary winding 50a, fourth switch S4, and primary negative terminal 42. As a result, a positive voltage is applied to the primary winding 50a, and a positive voltage is induced in the secondary winding 50b. In the secondary circuit 52, current flows in the following order: secondary negative terminal 44, sixth switch S6, body diode D6 of the sixth switch S6, secondary winding 50b, secondary reactor 55b, and secondary positive terminal 43.

[0079] During the second period TA2, the third switch S3 is turned on and the fourth switch S4 is turned off, based on the drive states of the switches S1 to S6 during the first period TA1. In this case, as shown in FIG. 10 , in the primary circuit 51, a return current flows through a path including the first switch S1, the primary reactor 55a, the primary winding 50a, the third switch S3, and the body diode D3 of the third switch S3. In the secondary circuit 52, a current flows through the same path as in the first period TA1. During the first period TA1 and the second period TA2, power is transmitted from the primary circuit 51 to the secondary circuit 52.

[0080] 11, in the third period TA3, the switches S1 to S6 are in the same drive state as in the second period TA2, and a current flows in the opposite direction to the current path described in the second period TA2. The current flows in the path shown in FIG. 11 because the sixth switch S6 is turned on.

[0081] During the fourth period TA4, the second, third, and fifth switches S2, S3, and S5 are turned on, and the first, fourth, and sixth switches S1, S4, and S6 are turned off. In this case, as shown in FIG. 12 , in the secondary circuit 52, current flows in the following order: secondary positive terminal 43, secondary reactor 55b, secondary winding 50b, fifth switch S5, and secondary negative terminal 44. As a result, a negative voltage is applied to the secondary winding 50b, and a negative voltage is induced in the primary winding 50a. In the primary circuit 51, current flows in the following order: primary negative terminal 42, second switch S2, body diode D2 of the second switch S2, primary reactor 55a, primary winding 50a, third switch S3, body diode D3 of the third switch S3, and primary positive terminal 41. The current flows through the path shown in FIG. 12 because the fifth switch S5 is turned on.

[0082] In the fifth period TA5, as shown in FIG. 13, the switches S1 to S6 are in the same driving state as in the fourth period TA4, and current flows in the opposite direction to the current path described in the fourth period TA4.

[0083] During the sixth period TA6, the fourth switch S4 is turned on and the third switch S3 is turned off, based on the drive states of the switches S1 to S6 during the fifth period TA5. In this case, as shown in FIG. 14, in the primary circuit 51, a return current flows through a path including the second switch S2, the fourth switch S4, the body diode D4 of the fourth switch S4, the primary winding 50a, and the primary reactor 55a. In the secondary circuit 52, a current flows through the same path as in the fifth period TA5. During the fifth period TA5 and the sixth period TA6, power is transmitted from the primary circuit 51 to the secondary circuit 52.

[0084] 15, in the seventh period TA7, the switches S1 to S6 are in the same drive state as in the sixth period TA6, and a current flows in the opposite direction to the current path described in the sixth period TA6. The current flows in the path shown in FIG. 15 because the fifth switch S5 is turned on.

[0085] During the eighth period TA8, the first, fourth, and sixth switches S1, S4, and S6 are turned on, and the second, third, and fifth switches S2, S3, and S5 are turned off. In this case, as shown in FIG. 16 , in the secondary circuit 52, current flows in the following order: secondary positive terminal 43, secondary reactor 55b, secondary winding 50b, sixth switch S6, and secondary negative terminal 44. As a result, a positive voltage is applied to the secondary winding 50b, and a positive voltage is induced in the primary winding 50a. In the primary circuit 51, current flows in the following order: primary negative terminal 42, fourth switch S4, body diode D4 of the fourth switch S4, primary winding 50a, primary reactor 55a, first switch S1, and body diode D1 of the first switch S1. The current flows through the path shown in FIG. 16 because the sixth switch S6 is turned on.

[0086] Next, the case where the voltage step-up operation of the power converter 40 is performed will be described.

[0087] The output signal generating unit 16b generates drive signals for the first to fourth switches S1 to S4 based on the drive signals for the fifth and sixth switches S5 and S6 generated by the input signal generating unit 16a. In this embodiment, the output signal generating unit 16b generates synchronization signals synchronized with the drive signal for the fifth switch S5 as the drive signals for the first and fourth switches S1 and S4. The output signal generating unit 16b generates synchronization signals synchronized with the drive signal for the sixth switch S6 as the drive signals for the second and third switches S2 and S3. More specifically, the drive signals for the first and fourth switches S1 and S4 are signals obtained by inverting the ON command and OFF command of the drive signal for the fifth switch S5. The drive signals for the second and third switches S2 and S3 are signals obtained by inverting the ON command and OFF command of the drive signal for the sixth switch S6.

[0088] An example of switching control for maintaining the continuous current mode during boost operation is shown in Fig. 17. In Fig. 17, (a), (d), and (e) correspond to (a), (d), and (e) in Fig. 8, (b) shows the on / off states of the first and fourth switches S1 and S4, and (c) shows the on / off states of the second and third switches S2 and S3.

[0089] 18 to 23 show paths of current flowing through the power converter 40 during periods TB1 to TB8 of one switching period TB. In Fig. 18 to Fig. 23, the parasitic capacitance of each of the switches S1 to S6 is shown.

[0090] Of the periods TB1 to TB8, in the third period TB3 and the seventh period TB7, the secondary current Ior is allowed to flow in the direction of power transmission from the primary circuit 51 to the secondary circuit 52. The paths of the current flowing through the power converter 40 in the periods TB1 to TB8 will be described in detail below.

[0091] During the first period TB1, the fifth and sixth switches S5 and S6 are turned on, and the first to fourth switches S1 to S4 are turned off. In this case, as shown in FIG. 18 , current flows through two current paths in the secondary circuit 52. In the first current path, current flows through the secondary positive terminal 43, the secondary reactor 55b, the secondary winding 50b, the fifth switch S5, and the secondary negative terminal 44 in this order. In the second current path, current flows through the secondary positive terminal 43, the secondary reactor 55b, the secondary winding 50b, the sixth switch S6, and the secondary negative terminal 44 in this order. This causes magnetic energy to accumulate in the secondary reactor 55b. Note that during the operation shown in FIG. 18 , power is not generally transmitted from the secondary circuit 52 to the primary circuit 51, and no current flows through the primary circuit 51.

[0092] During the second period TB2, the first, fourth, and sixth switches S1, S4, and S6 are turned on, and the second, third, and fifth switches S2, S3, and S5 are turned off. In this case, as shown in FIG. 19 , in the secondary circuit 52, current flows in the following order: secondary positive terminal 43, secondary reactor 55b, secondary winding 50b, sixth switch S6, and secondary negative terminal 44. As a result, a positive voltage is applied to the secondary winding 50b, and a positive voltage is induced in the primary winding 50a. In the primary circuit 51, current flows in the following order: primary negative terminal 42, fourth switch S4, body diode D4 of the fourth switch S4, primary winding 50a, primary reactor 55a, first switch S1, body diode D1 of the first switch S1, and primary positive terminal 41. In the second period TB2, power is transmitted from the secondary side circuit 52 to the primary side circuit 51.

[0093] During the third period TB3, as shown in Fig. 20, the switches S1 to S6 are in the same drive state as during the second period TB2, and a current flows in the opposite direction to the current path described for the second period TB2. The current flows through the path shown in Fig. 20 because the first and fourth switches S1 and S4 are turned on.

[0094] In the fourth period TB4, the fifth and sixth switches S5 and S6 are turned on, and the first to fourth switches S1 to S4 are turned off. In this case, as shown in FIG. 21, a current flows in the direction opposite to the direction of the current path described in the first period TB1.

[0095] In the fifth period TB5, the switches S1 to S6 are in the same drive state as in the first period TB1, and current flows through the same path as in the first period TB1 (see FIG. 18 above). As a result, magnetic energy is stored in the secondary reactor 55b.

[0096] During the sixth period TB6, the second, third, and fifth switches S2, S3, and S5 are turned on, and the first, fourth, and sixth switches S1, S4, and S6 are turned off. In this case, as shown in FIG. 22 , in the secondary circuit 52, current flows in the following order: secondary positive terminal 43, secondary reactor 55b, secondary winding 50b, fifth switch S5, and secondary negative terminal 44. As a result, a negative voltage is applied to the secondary winding 50b, and a negative voltage is induced in the primary winding 50a. In the primary circuit 51, current flows in the following order: primary negative terminal 42, second switch S2, body diode D2 of the second switch S2, primary reactor 55a, primary winding 50a, third switch S3, body diode D3 of the third switch S3, and primary positive terminal 41. In the sixth period TB6, power is transmitted from the secondary side circuit 52 to the primary side circuit 51.

[0097] During the seventh period TB7, as shown in Fig. 23, the switches S1 to S6 are in the same drive state as during the sixth period TB6, and a current flows in the opposite direction to the current path described for the sixth period TB6. The current flows through the path shown in Fig. 23 because the second and third switches S2 and S3 are turned on.

[0098] In the eighth period TA8, the switches S1 to S6 are in the same driving state as in the fourth period TB4, and current flows through the same path as in the fourth period TB4 (see FIG. 21).

[0099] In this embodiment, a drive signal is generated as the output drive signal to allow the secondary current Ior to flow in the direction of power transmission from the output circuit to the input circuit. Specifically, during voltage step-down operation, drive signals are generated for the fifth and sixth switches S5 and S6 to allow the secondary current Ior to flow in the direction of power transmission from the secondary circuit 52 to the primary circuit 51. During voltage step-up operation, drive signals are generated for the first to fourth switches S1 to S4 to allow the secondary current Ior to flow in the direction of power transmission from the primary circuit 51 to the secondary circuit 52.

[0100] By performing switching control based on the generated drive signals for each switch S1 to S6, the direction of the secondary current Ior is allowed to reverse within one switching period Ts, and the current mode of the power converter 40 is prevented from entering a discontinuous current mode. Therefore, for example, during a period when the charging and discharging of the storage battery 31 is switched, changes in the current response of the power converter 40 can be suppressed, and the controllability of the secondary current Ior can be improved. As a result, malfunctions in the power conversion system 10 can be prevented.

[0101] When the current mode of the power converter 40 is the continuous current mode, the occurrence of resonance is suppressed, unlike in the discontinuous current mode. When the occurrence of resonance is suppressed in switching control, the current change rate, which is the slope of the current Ibat of the storage battery 31 with respect to switching control variables such as the phase shift amount θd and the duty ratio Dd, is kept constant, as shown in Fig. 24. As a result, the controllability of the secondary-side current Ior can be improved during the switching period between charging and discharging of the storage battery 31.

[0102] When the current mode of the power converter 40 is the continuous current mode, the occurrence of resonance is suppressed because the voltage applied to the parasitic capacitance of each switch S1 to S6 is fixed at approximately 0 V. For example, during the step-down operation, the sixth switch S6 is turned on in the third and eighth periods TA3 and TA8, thereby fixing the voltage applied to the parasitic capacitance of the sixth switch S6 at approximately 0 V (see FIGS. 11 and 16). Furthermore, during the fourth and seventh periods TA4 and TA7, the fifth switch S5 is turned on, thereby fixing the voltage applied to the parasitic capacitance of the fifth switch S5 at approximately 0 V (see FIGS. 12 and 15). During the step-up operation, the first and fourth switches S1 and S4 are turned on in the third period TB3, thereby fixing the voltage applied to the parasitic capacitance of the first and fourth switches S1 and S4 at approximately 0 V (see FIG. 20). In addition, in the seventh period TB7, the voltage applied to the parasitic capacitances of the second and third switches S2 and S3 is fixed to approximately 0 V (see FIG. 23).

[0103] In addition to allowing the reactor current to flow in the direction of power transfer from the output circuit to the input circuit, an output drive signal is generated to turn on the MOSFET corresponding to the conducting body diode during a period of one switching period Ts when the body diode of the output circuit is conducting. In this case, current flows through the MOSFET and the body diode during a period of one switching period Ts when power is transferred from the input circuit to the output circuit. This reduces conduction loss in the output circuit when the power converter 40 operates in continuous current mode compared to when current flows only through the body diode of the MOSFET and the body diode. This makes it possible to improve power conversion efficiency while suppressing malfunctions in the power conversion system 10.

[0104] For example, during the step-down operation, the sixth switch S6 is turned on during the first and second periods TA1 and TA2, so that a current flows through the sixth switch S6 in addition to the body diode D6 (see FIGS. 9 and 10). During the fifth and sixth periods TA5 and TA6, the fifth switch S5 is turned on, so that a current flows through the fifth switch S5 in addition to the body diode D5 (see FIGS. 13 and 14). This makes it possible to reduce the conduction loss occurring in the secondary-side circuit 52 compared to the comparative example in which the fifth and sixth switches S5 and S6 are fixed off during the step-down operation.

[0105] For example, during the boost operation, in the second period TB2, the first and fourth switches S1 and S4 are turned on, causing a current to flow through the first and fourth switches S1 and S4 in addition to the body diodes D1 and D4 (see FIG. 19 ). In the sixth period TB6, the second and third switches S2 and S3 are turned on, causing a current to flow through the second and third switches S2 and S3 in addition to the body diodes D2 and D3 (see FIG. 22 ). This reduces the conduction loss in the primary-side circuit 51 compared to the comparative example in which the first to fourth switches S1 to S4 are fixed off during the boost operation.

[0106] A synchronization signal synchronized with the input drive signal is generated as the output drive signal. In this case, switching control is performed based on the input drive signal and the output drive signal, which is a synchronization signal, so that the current mode of the power converter 40 is maintained in a continuous current mode regardless of the operating region of the power converter 40. This prevents the current mode of the power converter 40 from switching, for example, during a period when the storage battery 31 switches between charging and discharging. This effectively suppresses changes in the current response of the power converter 40. Furthermore, during a period of one switching cycle Ts during which the body diode of the output circuit is conductive, the MOSFET corresponding to the conductive body diode can be accurately made conductive. This effectively reduces conduction loss in the output circuit.

[0107] FIG. 25 shows a comparison of power conversion efficiency between switching control when a synchronization signal is generated and switching control when a synchronization signal is not generated. In switching control when a synchronization signal is not generated, the switch of the output circuit is fixed off. In FIG. 25, when switching control is performed when a synchronization signal is not generated, the region of the secondary current Ior where the current mode of the power converter 40 is continuous current mode is shown as the CCM region. When switching control is performed when a synchronization signal is not generated, the region of the secondary current Ior where the current mode of the power converter 40 is discontinuous current mode is shown as the DCM region. The magnitude of the secondary current Ior at the boundary between the CCM region and the DCM region is shown as the boundary current value Ia.

[0108] In the CCM region, the generation of a synchronization signal reduces conduction loss in the output circuit compared to when a synchronization signal is not generated. Therefore, the power conversion efficiency of switching control when a synchronization signal is generated is higher than the power conversion efficiency of switching control when a synchronization signal is not generated. In the example shown in FIG. 25 , in the CCM region where the secondary current Ior is positive, it was confirmed that the power conversion efficiency was improved by 1.1% when a synchronization signal was generated compared to when a synchronization signal was not generated. Furthermore, in the CCM region where the secondary current Ior is negative, it was confirmed that the power conversion efficiency was improved by 1.2% when a synchronization signal was generated compared to when a synchronization signal was not generated.

[0109] In the DCM region, the generation of a synchronization signal increases the effective value of the current (i.e., the magnitude of the ripple current) flowing through each reactor 55a, 55b compared to when a synchronization signal is not generated. Accordingly, the power conversion efficiency of switching control when a synchronization signal is generated is lower than the power conversion efficiency of switching control when a synchronization signal is not generated. In other words, in the DCM region, power conversion efficiency can be improved by not generating a synchronization signal during switching control compared to when a synchronization signal is generated.

[0110] Here, it is considered that there are cases where controllability of the secondary current Ior is required and cases where controllability of the secondary current Ior is not required as much, depending on the operating conditions of the load 21. In cases where controllability of the secondary current Ior is not required as much, it is considered that there is room for improving the power conversion efficiency in switching control.

[0111] Therefore, the control device 16 includes a determination unit 16d as shown in Fig. 5. The determination unit 16d determines whether or not a synchronization signal needs to be generated in order to improve both the controllability of the secondary current Ior and the power conversion efficiency. The determination process performed by the determination unit 16d will be described in detail below.

[0112] The determination unit 16d acquires determination information Mj indicating the operating state of the load 21 and the secondary current Ior. For example, the determination information Mj is information indicating whether the rotating electric machine 23 is operating or stopped. The determination unit 16d can acquire the determination information Mj from the control device 24 of the inverter 22 (see FIG. 1).

[0113] Furthermore, for example, the determination information Mj is information indicating whether the storage battery 31 is being charged by an external charger. The external charger is, for example, a stationary charger provided outside the vehicle. Although not shown in the drawings, the high potential side terminal 11 and the low potential side terminal 12 are electrically connectable to the external charger. The determination unit 16d can obtain information indicating that the power conversion system 10 is electrically connected to the external charger as determination information Mj indicating that the storage battery 31 is being charged by the external charger.

[0114] The determination unit 16d determines whether or not the situation requires controllability of the secondary current Ior based on the acquired determination information Mj. In the present embodiment, the determination unit 16d determines that the situation requires controllability of the secondary current Ior when the acquired determination information Mj indicates that the rotating electric machine 23 is operating. The rotating electric machine 23 being in operation means, for example, that the vehicle is running. On the other hand, the determination unit 16d determines that the situation does not require controllability of the secondary current Ior when the acquired determination information Mj indicates that the rotating electric machine 23 is stopped or that the storage battery 31 is being charged by an external charger. The rotating electric machine 23 being stopped means, for example, that the vehicle is parked.

[0115] When the determination unit 16d determines that the situation does not require controllability of the secondary current Ior, the determination unit 16d further determines whether the magnitude of the secondary current Ior is greater than the current determination value Ij. In this embodiment, the current determination value Ij is set to the boundary current value Ia described above with reference to FIG.

[0116] When it is determined that the situation requires control of the secondary current Ior, the output signal generating unit 16b generates a synchronization signal as the output drive signal. When it is determined that the situation does not require control of the secondary current Ior and the magnitude of the secondary current Ior is greater than the current determination value Ij, the output signal generating unit 16b generates a synchronization signal as the output drive signal. On the other hand, when it is determined that the situation does not require control of the secondary current Ior and the magnitude of the secondary current Ior is equal to or less than the current determination value Ij, the output signal generating unit 16b generates an OFF command for one switching period Ts as the output drive signal instead of the synchronization signal.

[0117] 26 shows an example of a control procedure executed by the control device 16. This control is repeatedly executed at predetermined intervals.

[0118] In step S10, the determination unit 16d acquires determination information Mj. In step S11, the correction amount calculation unit 18a acquires the primary side terminal voltage VHr. The voltage deviation calculation unit 17a and the correction amount calculation unit 18a acquire the secondary side terminal voltage VLr. The voltage deviation calculation unit 17a acquires the secondary side command voltage VL*. In step S12, the determination unit 16d and the current deviation calculation unit 17c acquire the secondary side current Ior. The current deviation calculation unit 17c and the correction amount calculation unit 18a acquire the secondary side command current Io*. In this embodiment, the current deviation calculation unit 17c acquires the secondary side command current Io* calculated by the voltage deviation calculation unit 17a and the voltage feedback control unit 17b.

[0119] In step S13, the correction amount calculation unit 18a and the minimum value selection unit 18b execute feedforward control to set the secondary-side current Ior to the secondary-side command current Io*, thereby calculating the correction amount. In step S14, the current deviation calculation unit 17c and the current feedback control unit 17d calculate the feedback control amount. In steps S13 and S14, when a voltage step-up operation is performed, the correction amount Dff and the feedback control amount Dfb for the duty ratio Dd are calculated. In step S14, the correction amount θff and the feedback control amount θfb for the phase shift amount θd are calculated.

[0120] In step S15, the adder 18c corrects the feedback control amount based on the calculated correction amount to calculate a switching control amount. In this embodiment, the sum of the calculated feedback control amount and the correction amount is calculated as the switching control amount. The modulator 17f generates a drive signal for the switch of the input side circuit based on the calculated switching control amount. Note that in step S15, when a voltage step-up operation is performed, a duty ratio Dd is calculated as the switching control amount. When a voltage step-down operation is performed, a phase shift amount θd is calculated as the switching control amount.

[0121] In step S16, the determination unit 16d determines whether or not the situation requires control of the secondary current Ior based on the acquired determination information Mj. If a negative determination is made in step S16, the process proceeds to step S17. In step S17, the determination unit 16d determines whether or not the magnitude of the secondary current Ior is greater than the current determination value Ij.

[0122] If the determination in step S16 is affirmative, or if the determination in step S17 is affirmative, the process proceeds to step S 18. In step S18, the output signal generating section 16b generates a synchronization signal as an output drive signal.

[0123] If the determination in step S17 is negative, the process proceeds to step S19. In step S19, the output signal generating unit 16b generates an OFF command for one switching period Ts as an output drive signal. In step S20, the switching control unit 16c performs switching control based on the drive signals for each of the switches S1 to S6 generated by the input signal generating unit 16a and the output signal generating unit 16b.

[0124] In the above-described control, if a positive determination is made in step S16, a synchronization signal is generated. In this case, the current mode of power converter 40 is maintained in continuous current mode regardless of the operating region of power converter 40. If a negative determination is made in step S16 and a positive determination is made in step S17, a synchronization signal is generated in the CCM region. On the other hand, if a negative determination is made in steps S16 and S17, the switch of the output side circuit is fixed to off for one switching period Ts in the DCM region.

[0125] In this embodiment, it is determined based on the determination information Mj whether or not the situation requires controllability of the secondary current Ior. If it is determined that the situation requires controllability of the secondary current Ior, an output drive signal (specifically, a synchronization signal) is generated that allows the secondary current Ior to flow in the direction of power transmission from the output circuit to the input circuit. This prevents the current mode of the power converter 40 from becoming a discontinuous current mode in a situation where the charging / discharging of the storage battery 31 may be switched due to the operation of the load 21, thereby potentially switching the current mode of the power converter 40. This effectively prevents malfunctions in the power conversion system 10.

[0126] It is determined whether the magnitude of the secondary current Ior is greater than the current determination value Ij. If it is determined that the magnitude of the secondary current Ior is greater than the current determination value Ij, an output drive signal (specifically, a synchronization signal) is generated to turn on the MOSFET corresponding to the conducting body diode of the output circuit during a period of one switching period Ts during which the body diode is conducting. On the other hand, if it is determined that the magnitude of the secondary current Ior is smaller than the current determination value Ij, an OFF command is generated as the output drive signal for one switching period Ts. This makes it possible to generate an output drive signal for improving the power conversion efficiency according to the operating region of the power converter 40. Therefore, it is possible to accurately improve the power conversion efficiency in switching control.

[0127] When it is determined that the controllability of the secondary current Ior is not required, it is further determined whether the magnitude of the secondary current Ior is greater than the current determination value Ij. This makes it possible to generate an output drive signal that improves both the controllability of the secondary current Ior and the power conversion efficiency.

[0128] The input-side signal generating unit 16a calculates a feedback control amount as a manipulated variable for feedback-controlling the secondary-side current Ior to the secondary-side command current Io*. Furthermore, the feedback control amount is corrected by executing feedforward control, and a switching control amount is calculated. The input-side drive signal is generated based on the calculated switching control amount, thereby improving the controllability of the secondary-side current Ior as much as possible. In particular, when it is determined that the controllability of the secondary-side current Ior is not required and the magnitude of the secondary-side current Ior is determined to be equal to or less than the current determination value Ij, the current mode of the power converter 40 may be set to the discontinuous current mode. Even in this case, the controllability of the secondary-side current Ior can be improved as much as possible.

[0129] <Modification of First Embodiment> In step S18 in FIG. 26, the output signal generating unit 16b is not limited to generating a synchronization signal as the output drive signal.

[0130] For example, the output signal generator 16b may generate the output drive signal by delaying the on / off switching timing of the input drive signal by a predetermined period. The predetermined period may be set within a range that allows the secondary current Ior to flow in the direction of power transmission from the output circuit to the input circuit.

[0131] 27 , the output signal generation unit 16b may acquire the secondary current Ior in addition to the input drive signal. Based on the input drive signal and the direction of the secondary current Ior, the output signal generation unit 16b may generate an output drive signal that allows the secondary current Ior to flow in the direction of power transmission from the output circuit to the input circuit. The secondary current Ior may be a value detected by the current sensor 46.

[0132] Fig. 28 shows an example of a case where the step-down operation of the power converter 40 is performed. In Fig. 28, (a) to (e) correspond to (a) to (e) in Fig. 8.

[0133] The output signal generating unit 16b generates an ON command for the sixth switch S6 during a period TAa in one switching period TA when the drive signal for the first switch S1 is an ON command and the secondary current Ior is a negative value. The output signal generating unit 16b generates an ON command for the fifth switch S5 during a period TAb in one switching period Ts when the drive signal for the second switch S2 is an ON command and the secondary current Ior is a negative value.

[0134] Fig. 29 shows an example of the case where the voltage step-up operation of the power converter 40 is performed. In Fig. 29, (a) to (e) correspond to (a) to (e) of Fig. 17.

[0135] The output signal generating unit 16b generates an ON command for the first and fourth switches S1 and S4 during a period TBa in one switching period TB when the drive signal for only the fifth switch S5 of the fifth and sixth switches S5 and S6 is an OFF command and the secondary current Ior is a positive value. The output signal generating unit 16b generates an ON command for the second and third switches S2 and S3 during a period TBb in one switching period TB when the drive signal for only the sixth switch S6 of the fifth and sixth switches S5 and S6 is an OFF command and the secondary current Ior is a positive value.

[0136] In this embodiment, a drive signal that allows the secondary current Ior to flow in the direction of power transmission from the output circuit to the input circuit is generated as the output drive signal. Therefore, as described in the first embodiment, it is possible to suppress changes in the current response of the power converter 40 and improve the controllability of the secondary current Ior. As a result, it is possible to suppress malfunctions in the power conversion system 10.

[0137] For example, when the output signal generating unit 16b performs a step-down operation of the power converter 40, the output signal generating unit 16b may generate a signal that delays the on command for the fifth and sixth switches S5 and S6 by a predetermined period from the timing at which the secondary current Ior switches from a positive value to a negative value. Furthermore, when the output signal generating unit 16b performs a step-up operation of the power converter 40, the output signal generating unit 16b may generate a signal that delays the on command for the first and fourth switches S1 and S4 or the on command for the second and third switches S2 and S3 by a predetermined period from the timing at which the secondary current Ior switches from a negative value to a positive value.

[0138] Even when an output drive signal different from the synchronization signal is generated as in the above-described embodiments, switching control is performed based on the generated input drive signal and output drive signal, thereby allowing the direction of the secondary current Ior to be reversed and preventing the current mode of the power converter 40 from becoming a discontinuous current mode. This makes it possible to suppress changes in the current responsiveness of the power converter 40 and improve the controllability of the secondary current Ior.

[0139] For example, the output side signal generating unit 16b may generate an output side drive signal that turns on a MOSFET corresponding to a conducting body diode in the output side circuit during a period of one switching period Ts, based on the input side drive signal and the direction of the secondary side current Ior.

[0140] Specifically, a case where a step-down operation is performed will be described using the above-mentioned Fig. 28. The output-side signal generating unit 16b may generate an ON command for the sixth switch S6 during a period TAc of one switching cycle TA in which the drive signal for the first switch S1 is an ON command and the secondary-side current Ior has a positive value, instead of during a period TAa. The output-side signal generating unit 16b may generate an ON command for the fifth switch S5 during a period TAd of one switching cycle Ts in which the drive signal for the second switch S2 is an ON command and the secondary-side current Ior has a positive value, instead of during a period TAb.

[0141] Next, a case where the boost operation is performed will be described using FIG. 29 . Instead of the period TBa, the output signal generating unit 16b may generate an ON command for the first and fourth switches S1 and S4 during a period TBc in one switching cycle TB when the drive signal for only the fifth switch S5 of the fifth and sixth switches S5 and S6 is an OFF command and the secondary-side current Ior is a negative value. Instead of the period TBb, the output signal generating unit 16b may generate an ON command for the second and third switches S2 and S3 during a period TBd in one switching cycle TB when the drive signal for only the sixth switch S6 of the fifth and sixth switches S5 and S6 is an OFF command and the secondary-side current Ior is a negative value.

[0142] In this embodiment, the output drive signal is generated to turn on the MOSFET corresponding to the conducting body diode of the output circuit during a period of one switching cycle Ts when the body diode is conducting. Therefore, as described in the first embodiment, when the power converter 40 operates in continuous current mode, the conduction loss generated in the output circuit can be reduced compared to when current flows only through the body diode of the MOSFET and the body diode. As a result, it is possible to improve the power conversion efficiency.

[0143] The current determination value Ij does not necessarily have to be set to the boundary current value Ia. For example, the current determination value Ij may be set to a value greater than or smaller than the boundary current value Ia, taking into account factors that affect power conversion efficiency (e.g., switching loss) in addition to conduction loss and loss due to ripple current.

[0144] 26, instead of making a determination based on the current determination value Ij, the determination unit 16d may determine whether the magnitude of the power transmitted between the primary side circuit 51 and the secondary side circuit 52 is greater than a predetermined power determination value. The power determination value can be set based on, for example, the boundary current value Ia.

[0145] The determination process in step S16 in Fig. 26 does not need to be performed. In this case, after the process in step S15, the process may proceed to step S17.

[0146] In this embodiment, the process of step S18 or the process of step S19 is executed depending on the result of the determination process of step S17. In this case, it is possible to perform switching control while improving the power conversion efficiency.

[0147] The determination process of step S17 in Fig. 26 does not need to be performed. In this case, if a negative determination is made in step S16, the process may proceed to step S19.

[0148] The determination processes of steps S16 and S17 in Fig. 26 may not be performed. In this case, the process may proceed to step S18 after the process of step S15.

[0149] Second Embodiment A second embodiment will be described below with reference to the drawings, focusing on differences from the first embodiment. In this embodiment, as shown in Fig. 30 , a power conversion system 10 includes three modules: a first storage battery module 30, a second storage battery module 60, and a third storage battery module 90. The first storage battery module 30 has the same configuration as the storage battery module 30 described above in Fig. 1 , and includes a storage battery 31 and a power converter 40.

[0150] Like the first storage battery module 30, the second storage battery module 60 and the third storage battery module 90 include storage batteries 61, 91 and power converters 70, 100. Hereinafter, the storage battery 31 and power converter 40 of the first storage battery module 30 will be referred to as the "first storage battery 31" and the "first power converter 40," the storage battery 61 and power converter 70 of the second storage battery module 60 will be referred to as the "second storage battery 61" and the "second power converter 70," and the storage battery 91 and power converter 100 of the third storage battery module 90 will be referred to as the "third storage battery 91" and the "third power converter 100."

[0151] 1 , the first power converter 40 includes a primary terminal pair consisting of a primary positive terminal 41 and a primary negative terminal 42, and a secondary terminal pair consisting of a secondary positive terminal 43 and a secondary negative terminal 44. The second power converter 70 includes a primary terminal pair consisting of a primary positive terminal 71 and a primary negative terminal 72, and a secondary terminal pair consisting of a secondary positive terminal 73 and a secondary negative terminal 74. The third power converter 100 includes a primary terminal pair consisting of a primary positive terminal 101 and a primary negative terminal 102, and a secondary terminal pair consisting of a secondary positive terminal 103 and a secondary negative terminal 104. In each storage battery module 30, 60, 90, the connection relationship between each terminal 41 to 44, 71 to 74, 101 to 104 of the corresponding power converter 40, 70, 100, the corresponding storage battery 31, 61, 91, and the load 21 is the same as in the case of the storage battery module 30 described above in Figure 1, so detailed explanation will be omitted.

[0152] In this embodiment, the battery monitoring devices 32, 62, 92 are provided corresponding to the respective storage batteries 31, 61, 91. For example, the first battery monitoring device 32 detects the terminal voltage, current, internal resistance, SOC, etc. of each battery cell constituting the first storage battery 31, and monitors the state of the first storage battery 31. The second battery monitoring device 62 monitors the state of the second storage battery 61, similar to the first battery monitoring device 32. The third battery monitoring device 92 monitors the state of the third storage battery 91, similar to the first battery monitoring device 32. The detected values ​​detected by the respective battery monitoring devices 32, 62, 92 are input to the control device 16 provided in the power conversion system 10.

[0153] Voltage sensors 45, 75, 105 and current sensors 46, 76, 106 are provided corresponding to each storage battery module 30, 60, 90. The first, second, and third voltage sensors 45, 75, 105 detect primary-side terminal voltages VH1r, VH2r, VH3r of the corresponding power converters 40, 70, 100 and secondary-side terminal voltages VL1r, VL2r, VL3r of the corresponding power converters 40, 70, 100. The first, second, and third current sensors 46, 76, 106 detect secondary-side currents Io1r, Io2r, Io3r flowing through the secondary sides of the corresponding power converters 40, 70, 100. The detected values ​​of each sensor 45, 46, 75, 76, 105, 106 are input to the control device 16.

[0154] Based on the various detected values ​​input, the control device 16 performs switching control of the power converters 40, 70, and 100. In this embodiment, the control device 16 performs the control described above in Fig. 26 for each of the first power converter 40, the second power converter 70, and the third power converter 100. In this case, in this embodiment as well, it is possible to reduce the capacity of each of the power converters 40, 70, and 100, as in the first embodiment.

[0155] Specifically, the secondary-side terminal voltages VL1r, VL2r, and VL3r applied to the secondary-side terminal pairs of each power converter 40, 70, and 100 are the differential voltages between the voltages across each path 13 and 14 and the voltages Vbat1, Vbat2, and Vbat3 of the corresponding storage batteries 31, 61, and 91. Each secondary-side terminal voltage VL1r, VL2r, and VL3r is lower than the primary-side terminal voltages VH1r, VH2r, and VH3r applied to the primary-side terminal pairs. Therefore, the secondary-side rated voltage on the secondary side of each power converter 40, 70, and 100 can be set lower than the rated voltage of the corresponding storage battery 31, 61, and 91, thereby enabling the capacity of each power converter 40, 70, and 100 to be reduced.

[0156] In this embodiment, the series-connected secondary terminal pairs and storage batteries in each of the storage battery modules 30, 60, and 90 are connected in parallel to each other. In this case, for example, when the output voltage of one of the storage battery modules 30, 60, and 90 fluctuates, it may be necessary to quickly adjust the secondary terminal voltages of the other storage battery modules. Therefore, in each of the power converters 40, 70, and 100, it is advantageous to generate an output drive signal that allows the secondary current Ior to flow in the direction of power transmission from the output circuit to the input circuit in order to improve the controllability of the secondary currents Io1r, Io2r, and Io3r.

[0157] Other Embodiments The above-described embodiments may be modified as follows.

[0158] The secondary circuit of the power converter is not limited to the center tap circuit described above with reference to Fig. 2. For example, as shown in Fig. 31, the power converter 140 may have a secondary circuit 152.

[0159] In the secondary circuit 152, the source of the fifth switch S5 is electrically connected to a first end of the secondary winding 50b. The source of the sixth switch S6 is electrically connected to a second end of the secondary winding 50b. The drains of the fifth switch S5 and the sixth switch S6 are electrically connected to a first end of the secondary reactor 55b. The center tap of the secondary winding 50b is electrically connected to the secondary negative terminal 44 and the second end of the secondary capacitor 54.

[0160] The secondary circuit of the power converter is not limited to a center tap circuit, and may be a current-fed circuit. For example, as shown in FIG. 32, a power converter 240 may have a secondary circuit 252 provided with fifth to eighth switches S5 to S8. N-channel MOSFETs are used as the fifth to eighth switches S5 to S8. The fifth, sixth, seventh, and eighth switches S5, S6, S7, and S8 have body diodes D5, D6, D7, and D8.

[0161] The drain of the fifth switch S5 and the drain of the seventh switch S7 are electrically connected to a first end of the secondary-side reactor 55b. The source of the fifth switch S5 is electrically connected to a drain of the sixth switch S6. The source of the seventh switch S7 is electrically connected to a drain of the eighth switch S8. The sources of the sixth switch S6 and the eighth switch S8 are electrically connected to the secondary-side negative terminal 44 and the second end of the secondary-side capacitor 54.

[0162] A first end of the secondary winding 50b is electrically connected to the source of the fifth switch S5 and the drain of the sixth switch S6. A second end of the secondary winding 50b is electrically connected to the source of the seventh switch S7 and the drain of the eighth switch S8. The fifth to eighth switches S5 to S8 are controlled by the control device 16.

[0163] In each of the above embodiments, the switch constituting the secondary circuit may be a bidirectional switch, as described below. The bidirectional switch is used to enable the secondary terminal voltage to be selected and output as either a positive voltage, which has the same polarity as the storage battery, or a negative voltage, which has a polarity different from that of the storage battery. This makes it possible to add the secondary terminal voltage to the voltage of the storage battery or subtract the secondary terminal voltage from the voltage of the storage battery.

[0164] For example, as shown in FIG. 33 , the switches constituting the secondary circuit 52 described above in FIG. 2 may be replaced by first and second bidirectional switches Q1 and Q2. Each of the bidirectional switches Q1 and Q2 is composed of a pair of switches. Specifically, the first bidirectional switch Q1 is composed of a first positive switch QH1 and a first negative switch QL1. The second bidirectional switch Q2 is composed of a second positive switch QH2 and a second negative switch QL2. In this embodiment, N-channel MOSFETs are used as the switches QH1, QL1, QH2, and QL2. Furthermore, the switches QH1, QL1, QH2, and QL2 each have a body diode DH1, DL1, DH2, and DL2.

[0165] The sources of the first positive switch QH1 and the first negative switch QL1 are electrically connected to each other, and the sources of the second positive switch QH2 and the second negative switch QL2 are electrically connected to each other.

[0166] The drain of the first positive switch QH1 is electrically connected to a first end of the secondary winding 50b. The drain of the second positive switch QH2 is electrically connected to a second end of the secondary winding 50b. The drains of the first negative switch QL1 and the second negative switch QL2 are electrically connected to the secondary negative terminal 44 and the second end of the secondary capacitor 54.

[0167] For example, when the polarity of the secondary-side command voltage VL* is positive, the control device 16 generates drive signals to fix the negative switches QL1 and QL2 to ON. In this case, the control device 16 generates drive signals for the first to fourth switches S1 to S4 and the positive switches QH1 and QH2, as in the case described above with reference to FIG.

[0168] For example, when the polarity of the secondary-side command voltage VL* is negative, the control device 16 generates drive signals to fix the positive switches QH1, QH2 to ON. In this case, the control device 16 generates drive signals for the first to fourth switches S1 to S4 and the negative switches QL1, QL2.

[0169] Even with the circuit configurations shown in Figures 31, 32, and 33, power can be transmitted between the primary and secondary circuits. In this case, the control device 16 can generate an output drive signal that allows the secondary current Ior to flow in the direction of power transmission from the output circuit to the input circuit. The control device 16 can generate an output drive signal that turns on the MOSFET corresponding to the conducting body diode during the period in one switching period Ts when the body diode of the output circuit is conducting. The control device 16 can also perform the control described above in Figure 26.

[0170] In each of the above embodiments, the reactor included in the power converter may be one that takes into account the leakage inductance of the transformer. In this case, for example, the power converter may include only the secondary reactor out of the primary reactor and the secondary reactor. Furthermore, the primary reactor and the secondary reactor are not limited to being arranged as shown in FIG. 2 above, and may be provided in other locations in the corresponding circuits.

[0171] In each of the above embodiments, switches with small parasitic capacitance may be selected as the switches constituting the primary side circuit and the secondary side circuit. For example, it is possible to select switches with small parasitic capacitance by focusing on the rated voltage and rated current of the switches.

[0172] When the parasitic capacitance of the switch is small, distortion of the secondary current Ior is suppressed even if a resonance phenomenon occurs in the discontinuous current mode. Therefore, even if there is a possibility that the current mode of the power converter 40 will be the discontinuous current mode, the controllability of the secondary current Ior can be improved as much as possible.

[0173] 34 , the power conversion system 10 may be configured to be able to switch the electrical connection relationship between the storage battery modules 30, 60, and 90. The power conversion system 10 may include first, second, and third high-potential-side switches 301 a, 302 a, and 303 a, and first, second, and third low-potential-side switches 301 b, 302 b, and 303 b. Each of the switches 301 a, 302 a, 303 a, 301 b, 302 b, and 303 b is a relay or a semiconductor switching element.

[0174] The first high potential side switch 301a is provided in the high potential side path 13 closer to the first storage battery module 30 than the connection point with the second storage battery module 60. The first low potential side switch 301b is provided in the low potential side path 14 closer to the first storage battery module 30 than the connection point with the second storage battery module 60, and on the lower potential side than the connection point with the primary side negative terminal 42 of the first power converter 40.

[0175] The second high-potential-side switch 302a is provided in a path that electrically connects the secondary-side positive terminal 73 of the second power converter 70 and the high-potential-side path 13. The second low-potential-side switch 302b is provided in a path that electrically connects the negative terminal of the second storage battery 61 and the low-potential-side path 14, on the lower-potential side of the connection point with the primary-side negative terminal 72 of the second power converter 70.

[0176] The third high-potential-side switch 303a is provided in a path electrically connecting the secondary-side positive terminal 103 of the third power converter 100 and the high-potential-side path 13. The third low-potential-side switch 303b is provided in a path electrically connecting the negative terminal of the third storage battery 91 and the low-potential-side path 14, on the lower potential side of the connection point with the primary-side negative terminal 102 of the third power converter 100.

[0177] The power conversion system 10 may include a first connection path 304 and a second connection path 305. A first end of the first connection path 304 is electrically connected to a portion of the low potential side path 14 between the negative terminal of the first storage battery 31 and the first low potential side switch 301b. A second end of the first connection path 304 is electrically connected to a portion of the path that electrically connects the secondary side positive terminal 73 of the second power converter 70 and the high potential side path 13 between the secondary side positive terminal 73 and the second high potential side switch 302a.

[0178] A first end of the second connection path 305 is electrically connected between the negative terminal of the second storage battery 61 and the second low-potential-side switch 302b in the path that electrically connects the negative terminal of the second storage battery 61 and the low-potential-side path 14. A second end of the second connection path 305 is electrically connected between the secondary-side positive terminal 103 and the third high-potential-side switch 303a in the path that electrically connects the secondary-side positive terminal 103 of the third power converter 100 and the high-potential-side path 13.

[0179] The power conversion system 10 includes a first connection switch 306 and a second connection switch 307. Each of the connection switches 306, 307 is a relay or a semiconductor switching element. The first connection switch 306 is provided on the first connection path 304. The second connection switch 307 is provided on the second connection path 305.

[0180] The control device 16 may switch the electrical connection relationship between the load 21 and the storage battery modules 30, 60, and 90 by controlling the switches 301a, 302a, 303a, 301b, 302b, 303b, 306, and 307. For example, the control device 16 may turn on the switches 301a, 302a, 303a, 301b, 302b, and 303b and turn off the connection switches 306 and 307. In this case, the storage battery modules 30, 60, and 90 are electrically connected in parallel to the load 21. Alternatively, for example, the control device 16 may turn on the switches 301a, 303b, 306, and 307 and turn off the switches 301b, 302a, 302b, and 303a. In this case, the storage battery modules 30, 60, and 90 are electrically connected in series to the load 21.

[0181] In this embodiment, when each storage battery module 30, 60, 90 is electrically connected in parallel to the load 21, the control device 16 can execute the control described above in FIG. 26 in each power converter 40, 70, 100, as in the second embodiment.

[0182] The secondary terminal pair of the power converter may be electrically connected in series to the storage battery at the negative terminal side of the storage battery instead of the positive terminal side of the storage battery. In this case, the positive terminal side of the storage battery is electrically connected to the inverter 22 via the high-potential side path 13. The secondary positive terminal of the power converter is electrically connected to the negative terminal side of the storage battery. The secondary negative terminal of the power converter is electrically connected to the inverter 22 via the low-potential side path 14.

[0183] The first to eighth switches are not limited to N-channel MOSFETs, and may be, for example, IGBTs. In this case, the high-potential terminal of each switch is the collector, and the low-potential terminal is the emitter. A freewheel diode is connected in anti-parallel to each switch. In this embodiment, the freewheel diode connected in anti-parallel to each switch corresponds to a "rectifying element."

[0184] The power storage unit included in each power storage module is not limited to a storage battery. For example, it may be a large-capacity electric double layer capacitor, or may be both a storage battery and an electric double layer capacitor.

[0185] The power conversion system does not have to be configured as a storage battery module in which a storage battery, a power converter, and the like are integrated into a single package.

[0186] The power conversion system is not limited to being installed in a vehicle, but may also be installed in a moving object such as an aircraft or a ship. If the moving object is an aircraft, the rotating electric machine serves as the power source for the aircraft's flight, and if the moving object is a ship, the rotating electric machine serves as the power source for the ship's navigation. Furthermore, the power conversion system is not limited to being installed in a moving object, but can also be used as a stationary power source.

[0187] The control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the control unit and the method described herein may be implemented by a special-purpose computer configured by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described herein may be implemented by one or more special-purpose computers configured by combining a processor and memory programmed to perform one or more functions with a processor configured with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory tangible storage medium.

[0188] Characteristic configurations extracted from the above-described embodiments are described below. [Configuration 1] A control device (16) for a power converter applied to a system (10) including: a chargeable and dischargeable power storage unit (31, 61, 91); and a power converter (40, 70, 100, 140, 240) having a primary side circuit (51) and a secondary side circuit (52, 152, 252), wherein the primary side circuit has a pair of primary side terminals (41, 42, 71, 72, 101, 102) connected in parallel to the power storage unit, and the secondary side circuit has a pair of secondary side terminals (43, 44, 73, 74, 103, 104) connected in series to the power storage unit, the primary side circuit and the secondary side circuit have switches (S1 to S8, QH1, QL1, QH2, QL2) and rectifying elements (D1 to D8, DH1, DL1, DH2, DL2) connected in anti-parallel to the switches, the power converter has reactors (55a, 55b) and is configured to be able to execute switching control of the switches that cause current to flow through the reactors so as to transmit power from an input side circuit that is one of the primary side circuit and the secondary side circuit to an output side circuit that is the other, an input side signal generating unit (16a) that generates an input side drive signal for executing the switching control, which is a drive signal for the switch included in the input side circuit, based on a command value of the current flowing through the reactor; an output-side signal generating unit (16b) that generates, based on the input-side drive signal generated by the input-side signal generating unit, a drive signal for the switch included in the output-side circuit, the output-side drive signal allowing a current in the reactor to flow in a direction in which power is transmitted from the output-side circuit to the input-side circuit; and a control unit (16c) that performs the switching control based on the input-side drive signal generated by the input-side signal generating unit and the output-side drive signal generated by the output-side signal generating unit.[Configuration 2] The control device for a power converter according to Configuration 1, wherein the switch is a MOSFET, the rectifying element is a body diode of the MOSFET, and the output-side signal generating unit not only allows a current of the reactor to flow in a direction in which power is transmitted from the output-side circuit to the input-side circuit, but also generates the output-side drive signal that causes the MOSFET corresponding to the conducting body diode to conduct during a period in one switching cycle in which the body diode of the output-side circuit is conducting.[Configuration 3] A control device (16) for a power converter applied to a system (10) including: a chargeable and dischargeable power storage unit (31, 61, 91); and a power converter (40, 70, 100, 140, 240) having a primary side circuit (51) and a secondary side circuit (52, 152, 252), wherein the primary side circuit has a pair of primary side terminals (41, 42, 71, 72, 101, 102) connected in parallel to the power storage unit; the secondary side circuit has a pair of secondary side terminals (43, 44, 73, 74, 103, 104) connected in series to the power storage unit; the primary side circuit and the secondary side circuits include MOSFETs (S1 to S8, QH1, QL1, QH2, QL2) having body diodes (D1 to D8, DH1, DL1, DH2, DL2); the power converter has reactors (55a, 55b) and is capable of executing switching control of the switch that causes a current to flow through the reactor so as to transmit power from one of the input circuit, which is either the primary circuit or the secondary circuit, to the output circuit, which is the other; an input signal generation unit (16a) that generates, based on a command value of a current flowing through the reactor, an input drive signal for executing the switching control, which is a drive signal for the MOSFET in the input circuit; an output signal generation unit (16b) that generates, based on the input drive signal generated by the input signal generation unit, an output drive signal for the MOSFET in the output circuit, which is an output drive signal for turning on the MOSFET corresponding to the body diode that is turned on during a period in one switching cycle in which the body diode of the output circuit is turned on; and a control unit (16c) that performs the switching control based on the input drive signal generated by the input signal generation unit and the output drive signal generated by the output signal generation unit. [Configuration 4] The control device for a power converter according to any one of Configurations 1 to 3, wherein the output-side signal generation unit generates, as the output-side drive signal, a signal synchronized with the input-side drive signal.[Configuration 5] The control device for a power converter according to any one of Configurations 1, 2, and 4, wherein one of a secondary-side positive terminal (43, 73, 103) and a secondary-side negative terminal (44, 74, 104) constituting the secondary-side terminal pair is electrically connected to a positive side or a negative side of the power storage unit, and the other of the secondary-side positive terminal and the secondary-side negative terminal is electrically connected to a load (21), and the positive side or the negative side of the power storage unit, which is not connected to the secondary-side positive terminal or the secondary-side negative terminal, is electrically connected to the load, and further comprising a determination unit (16d) that determines whether or not a situation requires controllability of a current flowing through the reactor based on an operating state of the load, and the output-side signal generation unit generates the output-side drive signal on the condition that it is determined that a situation requires the controllability.[Configuration 6] One of the secondary-side positive terminal (43, 73, 103) and the secondary-side negative terminal (44, 74, 104) constituting the secondary-side terminal pair is electrically connected to the positive side or the negative side of the power storage unit, and the other of the secondary-side positive terminal and the secondary-side negative terminal is electrically connected to a load (21); one of the positive side and the negative side of the power storage unit that is not connected to the secondary-side positive terminal and the secondary-side negative terminal is electrically connected to the load; and a determination unit (16d) that determines whether or not controllability of a current flowing through the reactor is required based on an operating state of the load, wherein the output-side signal generation unit generates the output-side drive signal when it is determined that the controllability is required, and when it is determined that the controllability is not required, the determination unit further determines whether or not a magnitude of the current flowing through the reactor or a magnitude of power transmitted between the primary-side circuit and the secondary-side circuit is greater than a predetermined determination value. The control device for a power converter according to configuration 2 or 4, wherein the output-side signal generation unit generates the output-side drive signal when it is determined that the situation does not require controllability and that the magnitude of the current or the magnitude of the power is greater than the determination value, and generates the output-side drive signal to fix the MOSFET of the output-side circuit to off for one switching period when it is determined that the situation does not require controllability and that the magnitude of the current or the magnitude of the power is smaller than the determination value. [Configuration 7] The control device for a power converter according to configuration 3 or 4, further comprising a determination unit (16d) that determines whether the magnitude of the current flowing through the reactor or the magnitude of the power transferred between the primary-side circuit and the secondary-side circuit is greater than a predetermined determination value, and the output-side signal generation unit generates the output-side drive signal when it is determined that the magnitude of the current or the magnitude of the power is greater than the determination value, and generates the output-side drive signal to fix the MOSFET of the output-side circuit to off for one switching period when it is determined that the magnitude of the current or the magnitude of the power is smaller than the determination value.[Configuration 8] The control device for a power converter according to any one of Configurations 1 to 7, wherein the input-side signal generation unit comprises: a feedback control unit (17d) that calculates a switching control amount of the switch included in the input-side circuit as an operation amount for feedback-controlling the current flowing through the reactor to the command value; a correction unit (17e) that executes feedforward control to make the current flowing through the reactor the command value and corrects the switching control amount; and a modulation unit (17f) that generates the input-side drive signal based on the switching control amount corrected by the correction unit. [Configuration 9] The control device for a power converter according to any one of Configurations 1 to 8, wherein the system includes a plurality of the power storage units, and the power converters are provided corresponding to the plurality of power storage units, and in the plurality of power converters, one of a secondary-side positive terminal (43, 73, 103) and a secondary-side negative terminal (44, 74, 104) constituting the secondary-side terminal pair is connected to the positive side or the negative side of the corresponding power storage unit, and the other of the secondary-side positive terminal and the secondary-side negative terminal is connected to one of the external terminal pairs (11, 12) of the system, and the positive side or the negative side of the plurality of power storage units that is not connected to the secondary-side positive terminal and the secondary-side negative terminal is connected to the other of the external terminal pair.

[0189] Although the present disclosure has been described with reference to the embodiments, it is understood that the present disclosure is not limited to the embodiments or structures. The present disclosure also encompasses various modifications and equivalent modifications. In addition, various combinations and forms, including only one element, more than one element, or less than one element, are also within the scope and spirit of the present disclosure.

Claims

1. A control device (16) for a power converter applied to a system (10) including a chargeable and dischargeable power storage unit (31, 61, 91) and a power converter (40, 70, 100, 140, 240) having a primary side circuit (51) and a secondary side circuit (52, 152, 252), wherein the primary side circuit has a pair of primary side terminals (41, 42, 71, 72, 101, 102) connected in parallel to the power storage unit, and the secondary side circuit has a pair of secondary side terminals (43, 44, 73, 74, 103, 104) connected in series to the power storage unit, the primary side circuit and the secondary side circuit have switches (S1 to S8, QH1, QL1, QH2, QL2) and rectifying elements (D1 to D8, DH1, DL1, DH2, DL2) connected in anti-parallel to the switches, the power converter has reactors (55a, 55b) and is configured to be able to execute switching control of the switches that cause current to flow through the reactors so as to transmit power from an input side circuit that is one of the primary side circuit and the secondary side circuit to an output side circuit that is the other, an input side signal generating unit (16a) that generates an input side drive signal for executing the switching control, which is a drive signal for the switch included in the input side circuit, based on a command value of the current flowing through the reactor; an output-side signal generating unit (16b) that generates, based on the input-side drive signal generated by the input-side signal generating unit, a drive signal for the switch included in the output-side circuit, the output-side drive signal allowing a current in the reactor to flow in a direction in which power is transmitted from the output-side circuit to the input-side circuit; and a control unit (16c) that performs the switching control based on the input-side drive signal generated by the input-side signal generating unit and the output-side drive signal generated by the output-side signal generating unit.

2. The power converter control device according to claim 1, wherein the switch is a MOSFET, the rectifying element is a body diode of the MOSFET, and the output signal generating unit not only allows the current of the reactor to flow in a direction in which power is transmitted from the output circuit to the input circuit, but also generates the output drive signal that causes the MOSFET corresponding to the conducting body diode to conduct during a period in one switching cycle in which the body diode of the output circuit is conducting.

3. A control device (16) for a power converter applied to a system (10) including a chargeable and dischargeable power storage unit (31, 61, 91) and a power converter (40, 70, 100, 140, 240) having a primary side circuit (51) and a secondary side circuit (52, 152, 252), wherein the primary side circuit has a pair of primary side terminals (41, 42, 71, 72, 101, 102) connected in parallel to the power storage unit, the secondary side circuit has a pair of secondary side terminals (43, 44, 73, 74, 103, 104) connected in series to the power storage unit, and the primary side circuit and the secondary side circuit include MOSFETs (S1 to S8, QH1, QL1, QH2, QL2) having body diodes (D1 to D8, DH1, DL1, DH2, DL2), The power converter has reactors (55a, 55b) and is configured to be able to perform switching control of the MOSFET that causes a current to flow through the reactor so as to transmit power from an input circuit, which is one of the primary circuit and the secondary circuit, to an output circuit, which is the other of the primary circuit and the secondary circuit; an input signal generation unit (16a) that generates, based on a command value of a current flowing through the reactor, an input drive signal for executing the switching control, which is a drive signal for the MOSFET in the input circuit; an output signal generation unit (16b) that generates, based on the input drive signal generated by the input signal generation unit, an output drive signal for the MOSFET in the output circuit that causes the MOSFET corresponding to the body diode that is conducting during a period in one switching cycle in which the body diode of the output circuit is conducting; and a control unit (16c) that performs the switching control based on the input drive signal generated by the input signal generation unit and the output drive signal generated by the output signal generation unit. A control device for a power converter comprising:

4. A power converter control device according to any one of claims 1 to 3, wherein the output signal generating unit generates a signal synchronized with the input drive signal as the output drive signal.

5. A control device for a power converter according to claim 1 or 2, wherein one of the secondary side positive terminal (43, 73, 103) and the secondary side negative terminal (44, 74, 104) constituting the secondary side terminal pair is electrically connected to the positive side or the negative side of the storage unit, and the other of the secondary side positive terminal and the secondary side negative terminal is electrically connected to a load (21), and the positive side or the negative side of the storage unit that is not connected to the secondary side positive terminal or the secondary side negative terminal is electrically connected to the load, and further comprising a determination unit (16d) that determines whether or not controllability of the current flowing through the reactor is required based on the operating status of the load, and the output side signal generation unit generates the output side drive signal on the condition that it is determined that the situation requires controllability.

6. One of the secondary positive terminal (43, 73, 103) and the secondary negative terminal (44, 74, 104) constituting the secondary terminal pair is electrically connected to the positive or negative side of the power storage unit, and the other of the secondary positive terminal and the secondary negative terminal is electrically connected to a load (21); one of the positive and negative sides of the power storage unit that is not connected to the secondary positive and negative terminals is electrically connected to the load; and a determination unit (16d) that determines whether or not controllability of the current flowing through the reactor is required based on the operating status of the load; when it is determined that the controllability is required, the output signal generation unit generates the output drive signal; when it is determined that the controllability is not required, the determination unit further determines whether or not the magnitude of the current flowing through the reactor or the magnitude of the power transmitted between the primary circuit and the secondary circuit is greater than a predetermined determination value; 3. The control device for a power converter according to claim 2, wherein the output-side signal generating unit generates the output-side drive signal when it is determined that the situation does not require controllability and that the magnitude of the current or the magnitude of the power is greater than the determination value, and generates an output-side drive signal that fixes the MOSFET of the output-side circuit to off for one switching period when it is determined that the situation does not require controllability and that the magnitude of the current or the magnitude of the power is smaller than the determination value.

7. A control device for a power converter as described in claim 3, further comprising a judgment unit (16d) that judges whether the magnitude of the current flowing through the reactor or the magnitude of the power transmitted between the primary side circuit and the secondary side circuit is greater than a predetermined judgment value, wherein the output side signal generation unit generates the output side drive signal when it is judged that the magnitude of the current or the magnitude of the power is greater than the judgment value, and generates the output side drive signal that fixes the MOSFET of the output side circuit to be off for one switching period when it is judged that the magnitude of the current or the magnitude of the power is smaller than the judgment value.

8. A control device for a power converter as claimed in any one of claims 1, 2, 3, 6 and 7, wherein the input side signal generating unit comprises: a feedback control unit (17d) that calculates a switching control amount of the switch in the input side circuit as an operation amount for feedback controlling the current flowing through the reactor to the command value; a correction unit (17e) that executes feedforward control to make the current flowing through the reactor the command value and corrects the switching control amount; and a modulation unit (17f) that generates the input side drive signal based on the switching control amount corrected by the correction unit.

9. The control device for a power converter according to any one of claims 1, 2, 3, 6 and 7, wherein the system comprises a plurality of the power storage units, the power converters are provided corresponding to the plurality of power storage units, and in the plurality of power converters, one of the secondary side positive terminal (43, 73, 103) and the secondary side negative terminal (44, 74, 104) constituting the secondary side terminal pair is connected to the positive side or the negative side of the corresponding power storage unit, the other of the secondary side positive terminal and the secondary side negative terminal is connected to one of the external terminal pairs (11, 12) of the system, and the positive side or the negative side of the plurality of power storage units that is not connected to the secondary side positive terminal and the secondary side negative terminal is connected to the other of the external terminal pair.

10. A program applied to a system (10) including a chargeable and dischargeable power storage unit (31, 61, 91) and a power converter (40, 70, 100, 140, 240) having a primary side circuit (51) and a secondary side circuit (52, 152, 252), wherein the primary side circuit has a pair of primary side terminals (41, 42, 71, 72, 101, 102) connected in parallel to the power storage unit, the secondary side circuit has a pair of secondary side terminals (43, 44, 73, 74, 103, 104) connected in series to the power storage unit, the primary side circuit and the secondary side circuits have switches (S1 to S8, QH1, QL1, QH2, QL2) and rectifier elements (D1 to D8, DH1, DL1, DH2, DL2) connected in anti-parallel to the switches, the power converter has reactors (55a, 55b) and is configured to be able to execute switching control of the switch that causes a current to flow through the reactor so as to transmit power from an input side circuit, which is one of the primary side circuit and the secondary side circuit, to an output side circuit, which is the other; and the program causes a computer (16) to execute processes including: an input side signal generation process that generates, based on a command value of a current flowing through the reactor, an input side drive signal for executing the switching control, which is a drive signal for the switch in the input side circuit; an output side signal generation process that generates, based on the input side drive signal generated by the input side signal generation process, an output side drive signal for the switch in the output side circuit, which allows a current of the reactor to flow in a direction in which power is transmitted from the output side circuit to the input side circuit; and a control process that performs the switching control based on the input side drive signal generated by the input side signal generation process and the output side drive signal generated by the output side signal generation process.

11. A program applied to a system (10) including a chargeable and dischargeable power storage unit (31, 61, 91) and a power converter (40, 70, 100, 140, 240) having a primary side circuit (51) and a secondary side circuit (52, 152, 252), wherein the primary side circuit has a pair of primary side terminals (41, 42, 71, 72, 101, 102) connected in parallel to the power storage unit, the secondary side circuit has a pair of secondary side terminals (43, 44, 73, 74, 103, 104) connected in series to the power storage unit, and the primary side circuit and the secondary side circuits include MOSFETs (S1 to S8, QH1, QL1, QH2, QL2) having body diodes (D1 to D8, DH1, DL1, DH2, DL2), the power converter has reactors (55a, 55b) and is configured to be able to execute switching control of the MOSFET that causes a current to flow through the reactor so as to transmit power from an input side circuit, which is one of the primary side circuit and the secondary side circuit, to an output side circuit, which is the other of the primary side circuit and the secondary side circuit; and the program causing a computer (16) to execute processes including: an input side signal generation process that generates, based on a command value of a current flowing through the reactor, a drive signal for the MOSFET in the input side circuit, an input side drive signal for executing the switching control; an output side signal generation process that generates, based on the input side drive signal generated by the input side signal generation process, an output side drive signal for the MOSFET in the output side circuit, which is a drive signal for turning on the MOSFET corresponding to the body diode that is conducting during a period in one switching cycle that the body diode of the output side circuit is conducting; and a control process that performs the switching control based on the input side drive signal generated by the input side signal generation process and the output side drive signal generated by the output side signal generation process.

12. A control method for a power converter applied to a system (10) including a chargeable and dischargeable power storage unit (31, 61, 91), and a power converter (40, 70, 100, 140, 240) having a primary side circuit (51) and a secondary side circuit (52, 152, 252), wherein the primary side circuit has a pair of primary side terminals (41, 42, 71, 72, 101, 102) connected in parallel to the power storage unit, the secondary side circuit has a pair of secondary side terminals (43, 44, 73, 74, 103, 104) connected in series to the power storage unit, the primary side circuit and the secondary side circuits have switches (S1 to S8, QH1, QL1, QH2, QL2) and rectifier elements (D1 to D8, DH1, DL1, DH2, DL2) connected in anti-parallel to the switches, the power converter has a reactor (55a, 55b) and is configured to be able to perform switching control of the switch that causes a current to flow through the reactor so as to transmit power from an input side circuit, which is one of the primary side circuit and the secondary side circuit, to an output side circuit, which is the other of the primary side circuit and the secondary side circuit; and the control method for a power converter includes: an input side signal generating step of generating, based on a command value of a current flowing through the reactor, an input side drive signal for performing the switching control, which is a drive signal for the switch in the input side circuit; an output side signal generating step of generating, based on the input side drive signal generated in the input side signal generating step, an output side drive signal for the switch in the output side circuit, which allows the current of the reactor to flow in a direction in which power is transmitted from the output side circuit to the input side circuit; and a control step of performing the switching control based on the input side drive signal generated in the input side signal generating step and the output side drive signal generated in the output side signal generating step.

13. A control method for a power converter applied to a system (10) including a chargeable and dischargeable power storage unit (31, 61, 91) and a power converter (40, 70, 100, 140, 240) having a primary side circuit (51) and a secondary side circuit (52, 152, 252), wherein the primary side circuit has a pair of primary side terminals (41, 42, 71, 72, 101, 102) connected in parallel to the power storage unit, the secondary side circuit has a pair of secondary side terminals (43, 44, 73, 74, 103, 104) connected in series to the power storage unit, and the primary side circuit and the secondary side circuits include MOSFETs (S1 to S8, QH1, QL1, QH2, QL2) having body diodes (D1 to D8, DH1, DL1, DH2, DL2), the power converter has a reactor (55a, 55b) and is configured to be able to perform switching control of the MOSFET that causes a current to flow through the reactor so as to transmit power from an input side circuit, which is one of the primary side circuit and the secondary side circuit, to an output side circuit, which is the other of the primary side circuit and the secondary side circuit; and the control method for a power converter includes: an input side signal generating step of generating, based on a command value of the current flowing through the reactor, an input side drive signal for performing the switching control, which is a drive signal for the MOSFET in the input side circuit; an output side signal generating step of generating, based on the input side drive signal generated in the input side signal generating step, an output side drive signal for driving the MOSFET in the output side circuit, which is an output side drive signal for turning on the MOSFET corresponding to a body diode that is turned on during a period in one switching cycle in which the body diode of the output side circuit is turned on; and a control step of performing the switching control based on the input side drive signal generated in the input side signal generating step and the output side drive signal generated in the output side signal generating step.

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