Power conversion device

Abstract

To provide a power conversion device that can be easily reduced in a size, and can switch between a charging operation and a discharging operation without being stopped.SOLUTION: A power conversion device comprises: a first input / output terminal pair; a second input / output terminal pair; a first capacitor; a second capacitor; a first switching unit; a second switching unit; a transformer; and a control unit that switches between supplying a first pattern PWM signal to the first switching unit and the second switching unit to perform a charging operation, and supplying a second pattern PWM signal to the first switching unit and the second switching unit to perform a discharging operation. In response to a change of a command received from a host device, the control unit replaces the PWM signal supplied to the first switching unit and the PWM signal supplied to the second switching unit with each other, to switch the charging operation and the discharging operation.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a power conversion device. [Background technology]

[0002] Conventionally, in a bidirectional DC / DC converter, which is a power conversion device, a technology has been proposed in which an additional circuit is provided in the DC / DC converter and the additional circuit is used to switch between charging and discharging operations, as described in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-131446 A Summary of the Invention [Problem to be solved by the invention]

[0004] In a bidirectional DC / DC converter, if it is possible to switch between charging and discharging operations without stopping the DC / DC converter, it is suitable for buying and selling electricity from and to a grid, charging and discharging electric vehicles, etc. However, if an additional circuit is provided in the DC / DC converter to switch between charging and discharging operations, it becomes difficult to reduce the size of the DC / DC converter.

[0005] An object of one aspect of the disclosed technique is to provide a power conversion device that is easily miniaturized and capable of switching between a charging operation and a discharging operation without stopping. [Means for solving the problem]

[0006] One aspect of the disclosed technology is exemplified by a power conversion device as follows. The power conversion device includes a first input / output terminal pair, a second input / output terminal pair, a first capacitor connected in parallel to the first input / output terminal pair, a first switching unit connected to the first capacitor, a second switching unit connected to the second capacitor, a transformer disposed between the first switching unit and the second switching unit, and a control unit that switches between a charging operation in which a PWM signal of a first pattern is supplied to the first switching unit and the second switching unit to control the output of a current from the first input / output terminal pair, and a discharging operation in which a PWM signal of a second pattern is supplied to the first switching unit and the second switching unit to control the output of a current from the second input / output terminal pair. The control unit switches between the charging operation and the discharging operation by interchanging a PWM signal supplied to the first switching unit and a PWM signal supplied to the second switching unit in response to a change in the sign of a command value received from a higher-level device.

[0007] According to the present power conversion device, the PWM signal supplied to the first switching unit and the PWM signal supplied to the second switching unit are interchanged in response to a change in the sign of the command value, thereby realizing switching between the discharging operation and the charging operation. Therefore, it is not necessary to stop the power conversion device when switching between the discharging operation and the charging operation. Furthermore, according to the present power conversion device, it is not necessary to provide an additional circuit for switching between the discharging operation and the charging operation, which facilitates miniaturization.

[0008] The power conversion device may further include the following feature: when the switching of the PWM signal causes a period from switching between the discharging operation and the charging operation to a rising edge of the PWM signal to be shorter than a predetermined period, the control unit determines whether the period until the rising edge is longer than the predetermined period. The control unit delays the rising edge of the PWM signal for a period shorter than a predetermined period. Furthermore, when the switching of the PWM signals causes the period from switching between the discharging operation and the charging operation to the falling edge of the PWM signal to be shorter than a predetermined period, the control unit suppresses the supply of the PWM signal for a period shorter than the predetermined period. By providing such a feature, the power conversion device can ensure dead time and suppress the flow of unwanted current.

[0009] In the power conversion device, the control unit may switch from the discharging operation to the charging operation when the sign of the command value changes from positive to negative. Also, in the power conversion device, the control unit may switch from the charging operation to the discharging operation when the sign of the command value changes from negative to positive. By having such a feature, the power conversion device can flexibly switch between the charging operation and the discharging operation in response to a command value from a higher-level device.

[0010] In the power conversion device, when the control unit receives from the upper device a first step-down signal instructing a first step-down mode in which a first voltage input to the first input / output terminal pair is stepped down to a second voltage output from the second input / output terminal pair, the control unit sets a first phase shift amount of the first switching unit and the second switching unit to comply with the step-down signal, and when the control unit receives from the upper device a second step-down signal instructing a second step-down mode in which a first voltage input to the first input / output terminal pair is stepped down to a third voltage output from the second input / output terminal pair after receiving the first step-down signal, the control unit sets a second phase shift amount of the first switching unit and the second switching unit to comply with the second step-down signal and replaces a PWM signal supplied to the first switching unit with a PWM signal supplied to the second switching unit. By having such a feature, the power conversion device can switch between a charging operation and a discharging operation when switching from the first step-down mode to the second step-down mode.

[0011] In the power conversion device, when the control unit receives a boost signal from the upper device instructing a boost mode in which a first voltage input to the first input / output terminal pair is boosted to a second voltage output from the second input / output terminal pair, the control unit sets a first phase shift amount of the first switching unit and the second switching unit to follow the boost signal, and when the control unit receives a step-down signal from the upper device instructing a step-down mode in which a first voltage input to the first input / output terminal pair is lowered to a fourth voltage output from the second input / output terminal pair after receiving the boost signal and the command changes, the control unit sets a second phase shift amount of the first switching unit and the second switching unit to follow the step-down signal and replaces the PWM signal supplied to the first switching unit and the PWM signal supplied to the second switching unit. By having such a feature, the power conversion device can switch between a charging operation and a discharging operation when switching from the boost mode to the step-down mode.

[0012] In the power conversion device, when the control unit receives a step-down signal from the upper device instructing a step-down mode in which a first voltage input to the first input / output terminal pair is stepped down to a second voltage output from the second input / output terminal pair, the control unit sets a first phase shift amount of the first switching unit and the second switching unit to comply with the step-down signal, and when the control unit receives a step-up signal from the upper device instructing a step-up mode in which the first voltage input to the first input / output terminal pair is stepped up to a fifth voltage output from the second input / output terminal pair after receiving the step-down signal and the command changes, the control unit sets a second phase shift amount of the first switching unit and the second switching unit to comply with the step-up signal and replaces the PWM signal supplied to the first switching unit with the PWM signal supplied to the second switching unit. By having such a feature, the power conversion device can switch between a charging operation and a discharging operation when switching from the step-down mode to the step-up mode.

[0013] In the power conversion device, the control unit may be configured to, when receiving from the upper device a first boost signal instructing a first boost mode in which a first voltage input to the first input / output terminal pair is boosted to a sixth voltage output from the second input / output terminal pair, set a first phase shift amount of the first switching unit and the second switching unit to follow the first boost signal, and, when receiving from the upper device a second boost signal instructing a second boost mode in which a first voltage input to the first input / output terminal pair is boosted to a seventh voltage output from the second input / output terminal pair after receiving the first boost signal and the command is changed, set a second phase shift amount of the first switching unit and the second switching unit to follow the second boost signal, and replace a PWM signal supplied to the first switching unit with a PWM signal supplied to the second switching unit. By having such a feature, the power conversion device can switch between a charging operation and a discharging operation when switching from the first boost mode to the second boost mode. Effect of the Invention

[0014] According to the disclosed technique, it is possible to provide a power conversion device that is easily miniaturized and can switch between charging and discharging operations without stopping. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic configuration diagram of a power conversion device according to an embodiment. [Diagram 2] FIG. 2 is a control block diagram realized by the control unit. [Diagram 3] FIG. 3 is a first diagram illustrating a dead time securing process performed by the charge / discharge switching control unit. [Figure 4] FIG. 4 is a second diagram illustrating the dead time securing process by the charge / discharge switching control unit. [Diagram 5] FIG. 5 is a first diagram illustrating a pulse pattern of a PWM signal when the charge / discharge switching control unit according to the embodiment switches between a step-up mode, a step-down mode, and a charge / discharge operation. [Figure 6] FIG. 6 is a second diagram illustrating a pulse pattern of a PWM signal when the charge / discharge switching control unit according to the embodiment switches between the step-up mode, the step-down mode, and the charge / discharge operation. [Figure 7] FIG. 7 is a third diagram illustrating a pulse pattern of a PWM signal when the charge / discharge switching control unit according to the embodiment switches between the step-up mode, the step-down mode, and the charge / discharge operation. [Figure 8] FIG. 8 is a fourth diagram illustrating a pulse pattern of a PWM signal when the charge / discharge switching control unit according to the embodiment switches between the step-up mode, the step-down mode, and the charge / discharge operation. [Figure 9] FIG. 9 is a fifth diagram illustrating a pulse pattern of a PWM signal when the charge / discharge switching control unit according to the embodiment switches between the step-up mode, the step-down mode, and the charge / discharge operation. [Figure 10] FIG. 10 is a sixth diagram illustrating a pulse pattern of a PWM signal when the charge / discharge switching control unit according to the embodiment switches between the step-up mode, the step-down mode, and the charge / discharge operation. [Figure 11] FIG. 11 is a first diagram illustrating an example of a processing flow of the charge / discharge switching processing of the power conversion device according to the embodiment. [Figure 12] FIG. 12 is a second diagram illustrating an example of the processing flow of the charge / discharge switching processing of the power conversion device according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] [Application example] An application example of the present invention will be described below with reference to the drawings. The present invention is applied to a power conversion device 1 including an isolated bidirectional DC / DC converter 10 shown in Fig. 1. The power conversion device 1 comprises the DC / DC converter 10, a control unit 20, and two pairs of input / output terminals 13 (13p, 13m) and an input / output terminal pair 14 (14p, 14m). Capacitors C1 and C2 for smoothing the input voltage are connected between the input / output terminals 13m, 13p, and between the input / output terminals 14m, 14p, respectively.

[0017] The DC / DC converter 10 is an insulated bidirectional DC / DC converter whose main components are a transformer TR, two reactors Lr1 and Lr2, and two full-bridge circuits 11 and 12. The reactors Lr1 and Lr2 generate AC power under the control of the full-bridge circuits 11 and 12, and the capacitors C1 and C2 smooth the AC power into DC power. An insulating transformer can be used as the transformer TR, but a non-insulated reactor may also be used.

[0018] The full-bridge circuit 11 of the DC / DC converter 10 includes a leg L1 having a switching element Q1 and a switching element Q3 connected in series, and a leg L2 having a switching element Q2 and a switching element Q4 connected in series. As shown in the figure, a diode Dn (n=1 to 4) is connected in parallel between the terminals of the switching element Qn (n=1 to 4) of each leg. In addition, both the leg L1 and the leg L2 are connected to an input / output terminal pair 13. A connection point p1 between the switching element Q1 and the switching element Q3 of the leg L1 is connected to one end of the winding Wn1 of the transformer TR via a reactor Lr1, and a connection point p2 between the switching element Q2 and the switching element Q4 of the leg L2 is connected to the other end of the winding Wn1 of the transformer TR.

[0019] The full bridge circuit 12 of the DC / DC converter 10 includes a leg L3 having a switching element Q5 and a switching element Q7 connected in series, and a leg L4 having a switching element Q6 and a switching element Q8 connected in series. As shown in the figure, a diode Dn (n=5 to 8) is connected in parallel between the terminals of the switching element Qn (n=5 to 8) of each leg. In addition, both the leg L3 and the leg L4 are connected to an input / output terminal pair 14. In addition, a connection point p3 between the switching element Q5 and the switching element Q7 of the leg L3 is connected to one end of the winding Wn2 of the transformer TR via a reactor Lr2, and a connection point p4 between the switching element Q6 and the switching element Q8 of the leg L4 is connected to the other end of the winding Wn2 of the transformer TR.

[0020] 2 shows an example of a control block diagram realized by the control unit 20. The control unit 20 includes a control unit 23, a PWM generating unit 24, and a charge / discharge switching control unit .

[0021] The control unit 20 realizes a charging operation in which a PWM signal of a first pattern is supplied to each switching element Qn (n=1 to 8) of the full bridge circuits 11 and 12, and controls the switching elements Qn (n=1 to 8) to output a current from the input / output terminal pair 13. Also, the control unit 20 realizes a discharging operation in which a PWM signal of a second pattern is supplied to each switching element Qn (n=1 to 8) of the full bridge circuits 11 and 12, and controls the switching elements Qn (n=1 to 8) to output a current from the input / output terminal pair 14.

[0022] In this application example, switching between the discharging operation and the charging operation of the DC / DC converter 10 is performed by interchanging the PWM signals supplied to the switching elements Qn (n=1 to 4) of the full bridge circuit 11 and the switching elements Qm (m=5 to 8) of the full bridge circuit 12. Therefore, according to this application example, it is possible to switch between the charging operation and the discharging operation without stopping the DC / DC converter 10. Also, in this application example, it is not necessary to provide an additional circuit for switching between the discharging operation and the charging operation of the DC / DC converter 10, which facilitates miniaturization.

[0023] [Embodiment] Hereinafter, the power conversion device 1 according to the embodiment of the present invention will be described in more detail with reference to the drawings.

[0024] <Configuration of power conversion device> FIG. 1 is a schematic diagram of a power conversion device according to an embodiment. The power conversion device 1 according to this embodiment is a device capable of bidirectional power conversion. As shown in the figure, the power conversion device 1 includes a DC / DC converter 10, a control unit 20, and two pairs of input / output terminals 13 (13p, 13m) and an input / output terminal pair 14 (14p, 14m). In the input / output terminal pairs 13 and 14, the input / output terminals 13p, 14p are high-potential input / output terminals, and the input / output terminals 13m, 14m are low-potential input / output terminals. A capacitor C1 for smoothing input / output voltages is connected between the input / output terminals 13m, 13p. Similarly, a capacitor C2 for smoothing input / output voltages is connected between the input / output terminals 14m, 14p. Electrolytic capacitors can be used as the capacitors C1 and C2.

[0025] The DC / DC converter 10 is an insulated bidirectional DC / DC converter whose main components are a transformer TR, two reactors Lr1 and Lr2, and two full bridge circuits 11 and 12. Hereinafter, the full bridge circuit 11 on the left side and the full bridge circuit 12 on the right side in FIG. 1 will be referred to as the full bridge circuit 11 and the full bridge circuit 12, respectively. Similarly, the reactors Lr1 and Lr2 on the left side and the right side in FIG. 1 will be referred to as the reactor Lr1 and the reactor Lr2, respectively, and the winding Wn1 on the left side and the winding Wn2 on the right side in FIG. 1 of the transformer TR will be referred to as the winding Wn1 and the winding Wn2, respectively. In addition, the input / output terminal pair 13 (13p, 13m) and the input / output terminal pair 14 (14p, 14m) on the left side and the right side in FIG. 1 will be referred to as the input / output terminal pair 13 and the input / output terminal pair 14, respectively. The reactors Lr1 and Lr2 may utilize leakage inductance of the windings Wn1 and Wn2 of the transformer TR. The transformer TR of the DC / DC converter 10 does not need to have a turns ratio of 1:1. However, in the following, the configuration and operation of the power conversion device 1 will be described assuming that the turns ratio of the transformer TR is 1:1.

[0026] The full-bridge circuit 11 of the DC / DC converter 10 includes a leg L1 having a switching element Q1 and a switching element Q3 connected in series, and a leg L2 having a switching element Q2 and a switching element Q4 connected in series. As shown in the figure, a diode Dn (n=1 to 4) is connected in parallel between the terminals of the switching element Qn (n=1 to 4) of each leg. Each leg is connected to an input / output terminal pair 13, and a connection point p1 between the switching element Q1 and the switching element Q3 of the leg L1 is connected to one end of the winding Wn1 of the transformer TR via a reactor Lr1. A connection point p2 between the switching element Q2 and the switching element Q4 of the leg L2 is connected to the other end of the winding Wn1 of the transformer TR.

[0027] The full bridge circuit 12 of the DC / DC converter 10 includes a leg L3 having a switching element Q5 and a switching element Q7 connected in series, and a leg L4 having a switching element Q6 and a switching element Q8 connected in series. As shown in the figure, a diode Dn (n=5 to 8) is connected in parallel between the terminals of the switching element Qn (n=5 to 8) of each leg. In addition, both the leg L3 and the leg L4 are connected to an input / output terminal pair 14. In addition, a connection point p3 between the switching element Q5 and the switching element Q7 of the leg L3 is connected to one end of the winding Wn2 of the transformer TR via a reactor Lr2, and a connection point p4 between the switching element Q6 and the switching element Q8 of the leg L4 is connected to the other end of the winding Wn2 of the transformer TR.

[0028] The semiconductor materials for the switching elements Q1 to Q8 may be, but are not limited to, gallium nitride (GaN), silicon (Si), silicon carbide (SiC), etc. The semiconductor switching elements may be, for example, MOSFETs (Metal Oxide Semiconductor Field Effect Transistors), IGBTs (Insulated Gate Bipolar Transistors), etc. These semiconductors used as the switching elements Q1 to Q8 The diodes D1 to D8 are connected in anti-parallel to the switching elements.

[0029] The DC / DC converter 10 is equipped with various sensors (not shown) for measuring the magnitude of the input / output voltages and the input / output currents.

[0030] The control unit 20 is a unit that controls the DC / DC converter 10 (ON / OFF of each switching element in the DC / DC converter 10) by changing the level of a control signal to each switching element in the DC / DC converter 10. Hereinafter, the control signal for the switching element Qn (n=1 to 8) will be referred to as a control signal Gn.

[0031] The control unit 20 is composed of a processor (in this embodiment, a microcontroller), a gate driver, etc., and receives outputs from the various sensors described above.

[0032] The control unit 20 is configured (programmed) to determine whether the DC / DC converter 10 should operate as one of the following four types of converters based on the input data (current value, voltage value), and to control the DC / DC converter 10 to operate as the determined converter. Input / output terminal pair 13 is the primary side boost converter Input / output terminal pair 13 is the primary side of the step-down converter Input / output terminal pair 14 is the primary side boost converter Input / output terminal pair 14 is the primary side of the step-down converter

[0033] In addition, control unit 20 is configured (programmed) to instantly change the control content for DC / DC converter 10 (such as changing from control that causes DC / DC converter 10 to operate as a step-up converter on the input / output terminal pair 13 side as the primary side to control that causes DC / DC converter 10 to operate as a step-down converter on the input / output terminal pair 14 side as the primary side).

[0034] Fig. 2 is a control block diagram realized by the control unit 20. As shown in Fig. 2, in this embodiment, the DC / DC converter 10 is connected to an EV2 (electrically-driven automobile) and an inverter 30. The inverter 30 is a device that performs AC / DC conversion, and electrically connects the DC / DC converter 10 (direct current) to an AC power system 3. Examples of the EV2 include a BEV (Battery Electric Vehicle) that runs only on battery power, a PHV (Plug-in Hybrid Vehicle) that uses both a battery and an internal combustion engine, an FCV (Fuel Cell Vehicle) that runs on fuel cell power, and various other types of electrically-driven automobiles. However, the DC / DC converter 10 is not necessarily connected to an EV2. The DC / DC converter 10 is not limited to being used in such an EV 2, and may be connected to, for example, a home storage battery, etc. The DC / DC converter 10 may also be used for, for example, driving control of an electric vehicle that runs on DC power, or for control of various other electric devices.

[0035] The control unit 20 controls the DC / DC converter 10 according to command values ​​sent from a higher-level device. The command values ​​sent from the higher-level device to the control unit 20 are values ​​determined based on the remaining charge of the EV 2 and the power consumption of the load 4. The control unit 20 includes a CPU (Central Processing Unit), a ROM (read only memory), and a RAM (Random Access Memory ) and an input / output interface, and the CPU executes a computer program stored in the storage device to realize each of the functional blocks shown below. Using each of the functional blocks shown below, the control unit 20 generates a PWM signal according to a command value sent from a higher-level device and sends it to the DC / DC converter 10.

[0036] 2, the control unit 20 realizes a control unit 23, a PWM generating unit 24, a step-up / step-down switching control unit 25, and a charge / discharge switching control unit 26. Each functional block in the control unit 20 will be described below.

[0037] The control unit 23 generates a phase shift amount based on the difference between the actual current value of the electric path between the EV2 and the DC / DC converter 10 measured by the ammeter 21 and the command value sent from the higher-level device. The phase shift amount is the phase difference of the pulse-like control signals related to the ON / OFF of each switching element included in the legs L1 to L4. A specific method of generating the phase shift amount will be described later.

[0038] The PWM generating unit 24 generates a PWM signal based on the phase shift amount generated by the control unit 23. When generating the PWM signal, the PWM generating unit 24 uses a step-up / step-down signal output from the step-up / step-down switching control unit 25 and a charge / discharge signal output from the charge / discharge switching control unit 26. By using these signals output from the step-up / step-down switching control unit 25 and the charge / discharge switching control unit 26, the PWM generating unit 24 generates a PWM signal of a switching pattern for causing the DC / DC converter 10 to perform a step-up operation, a step-down operation, a charging operation, or a discharging operation. The PWM signal generated by the PWM generating unit 24 is sent to the DC / DC converter 10 and operates each of the switching elements Q1 to Q8.

[0039] The step-up / step-down switching control unit 25 generates a step-up / step-down signal based on the amount of phase shift output from the control unit 23. That is, the step-up / step-down switching control unit 25 selects whether the DC / DC converter 10 performs step-up operation or step-down operation based on the amount of phase shift output from the control unit 23. Then, the step-up / step-down switching control unit 25 outputs a signal according to the selection result.

[0040] The charge / discharge switching control unit 26 generates a charge / discharge signal based on a command value output from a higher-level device. That is, the charge / discharge switching control unit 26 selects whether the DC / DC converter 10 performs a charging operation or a discharging operation based on the command value output from the higher-level device. Then, the charge / discharge switching control unit 26 outputs a signal according to the selection result.

[0041] <Operation of the power conversion device> The operation of the power conversion device 1 according to this embodiment will be described below.

[0042] Basically, the DC / DC converter 10 can switch between the step-up operation and the step-down operation by relatively changing the phase shift amount related to ON / OFF of each switching element included in legs L1 to L4. That is, in the power conversion device 1 according to this embodiment, the control unit 20 can switch between the step-up operation and the step-down operation of the DC / DC converter 10 by changing the phase shift amount as follows.

[0043] For example, when the operation of the DC / DC converter 10 is switched from the step-down operation to the step-up operation with the input / output terminal pair 13 side as the primary side and the input / output terminal pair 14 side as the secondary side, the phase shift amount of the leg L2 relative to the leg L1 is transitioned to a predetermined value. Then, while maintaining the phase shift amount of the leg L2 relative to the leg L1 at the predetermined value, the phase shift amount of the leg L4 relative to the leg L2 is adjusted from the predetermined value to a desired phase value. Here, the phase shift amount of the leg L2 relative to the leg L1 can be expressed as a delay amount (TΦ) between the falling timing when the switching element Q1 changes from ON to OFF and the falling timing when the switching element Q2 changes from ON to OFF, or a delay amount (TΦ) between the falling timing when the switching element Q3 changes from ON to OFF and the falling timing when the switching element Q4 changes from ON to OFF. The phase shift amount of leg L4 with respect to leg L2 is the delay amount (TΦ) between the falling edge timing when switching element Q3 changes from ON to OFF and the falling edge timing when switching element Q7 changes from ON to OFF, or This can be expressed as the delay (TΦ) between the falling edge when switching element Q4 goes from ON to OFF and the falling edge when switching element Q7 goes from ON to OFF. Note that because the ON / OFF of switching elements Qn (n=1 to 8) changes at a predetermined period (T), the delay (TΦ) can also be expressed as a phase lead (TΦ).

[0044] Also, for example, when the operation of DC / DC converter 10 is switched from boost operation to buck operation with input / output terminal pair 13 side as the primary side and input / output terminal pair 14 side as the secondary side, the phase shift amount of switching element Q7 relative to switching elements Q1 and Q4, or the phase shift amount of switching element Q8 relative to switching elements Q3 and Q2 is reduced to a predetermined value. Then, the phase shift amount of switching element Q4 relative to switching element Q1, or the phase shift amount of switching element Q2 relative to switching element Q3 is adjusted from the predetermined value to a desired phase value. In this way, in power conversion device 1, the boost / buck operation is continuously switched by relatively changing the phase shift amount related to ON / OFF of each switching element included in legs L1 to L4.

[0045] In the following description, the terms "step-up operation" and "step-down operation" in DC / DC converter 10 refer to operations based on switching patterns relating to the ON / OFF of each switching element included in legs L1 to L4, and do not refer to the relationship between the input voltage and the output voltage relating to voltage conversion. That is, in this embodiment, DC / DC converter 10 may operate with "input voltage > output voltage" in "step-up operation", and may also operate with "input voltage < output voltage" in "step-down operation". The step-up operation of DC / DC converter 10 is also referred to as the "step-up mode", and the step-down operation is also referred to as the "step-down mode".

[0046] <Operation of the charge / discharge switching control unit 26> The operation of the charge / discharge switching control unit 26 included in the DC / DC converter 10 according to this embodiment will be described below.

[0047] Based on the command value output from the upper-level device, the charge / discharge switching control unit 26 determines whether to operate the DC / DC converter 10 in a charging operation or a discharging operation. For example, when controlling the current at the connection terminal between the EV2 and the DC / DC converter 10, if the current command value is greater than 0 A, the charge / discharge switching control unit 26 switches the DC / DC converter 10 to the charging operation. For example, if the current command value is less than 0 A, the charge / discharge switching control unit 26 switches the DC / DC converter 10 to the discharging operation. Also, for example, when the current command value is 0 A, the charge / discharge switching control unit 26 maintains the current state without switching between the charging operation and the discharging operation.

[0048] <Operation of the PWM generation unit 24> Subsequently, the operation details of the PWM generation unit 24 included in the DC / DC converter 10 according to this embodiment will be described. When the DC / DC converter 10 is switched between the charging operation and the discharging operation, the PWM generation unit 24 realizes this by swapping the PWM signal supplied to the switching element Qn (n = 1 to 4) belonging to the full-bridge circuit 11 and the PWM signal supplied to the switching element Qm (m = 5 to 8) belonging to the full-bridge circuit 12.

[0049] Here, when switching the operation between the charging operation and the discharging operation, if the dead time is insufficient in the switching elements belonging to the same leg, an unwanted current may flow in that leg. Therefore, the PWM generation unit 24 performs the following processing to ensure the dead time.

[0050] FIG. 3 is a first diagram illustrating the dead time ensuring process by the PWM generation unit 24. In FIG. 3, the dead time ensuring process for the switching elements Q(4n - 2) (n = 1 to 2), that is, the switching elements Q2 and Q6, is illustrated. In the example of FIG. 3, at time T1 It is assumed that charging and discharging are switched at the time of switching. Triangle Z1 in FIG. 3 illustrates a timer count. Signal P1 illustrates a waveform of a PWM signal supplied to switching elements Q2 and Q6. When the period from time T1 when switching between charging and discharging is performed to rising timer value T2 of the waveform of signal P1 is insufficient for a predetermined dead time, PWM generating unit 24 secures the dead time until the rising of the waveform of signal P1 by delaying the rising timer value of signal P1 until time T3 (lower limit value of the rising timer value) at which the dead time is secured. Note that when the period from time T1 to the rising timer value of the waveform of signal P1 is equal to or longer than the dead time, PWM generating unit 24 may output the rising timer value as it is.

[0051] FIG. 4 is a second diagram illustrating the dead time securing process by the PWM generating unit 24. FIG. 4 illustrates the dead time securing process for the switching element Q(4n) (n=1 to 2), that is, the switching elements Q4 and Q8. In the example of FIG. 4, it is assumed that the charge / discharge switching is performed at time T4. The triangle Z1 in FIG. 4 illustrates the timer count. The signal P2 illustrates the waveform of the PWM signal supplied to the switching elements Q4 and Q8. If the period from time T4 when the charge / discharge switching is performed to the falling timer value T5 of the waveform of the signal P2 is greater than a predetermined upper limit value, the PWM generating unit 24 outputs the predetermined upper limit value as the falling timer value. By limiting the falling timer value to the predetermined upper limit value, the supply of a PWM signal with insufficient dead time is suppressed. In addition, if the period from time T4 when the charge / discharge switching is performed to the falling timer value T5 of the waveform of the signal P2 is equal to or less than the predetermined upper limit value, the PWM generating unit 24 outputs the falling timer value T5 as it is. The predetermined upper limit value is set to, for example, the minimum value of the rising timer value.

[0052] In this embodiment, by swapping the PWM signal supplied to the switching elements Qn (n = 1 to 4) belonging to the full-bridge circuit 11 and the PWM signal supplied to the switching elements Qm (m = 5 to 8) belonging to the full-bridge circuit 12, the charge and discharge can be switched by switching between various switching modes as follows. · Step-down mode → Step-down mode · Boost mode → Step-down mode · Step-down mode → Boost mode · Boost mode → Boost mode

[0053] <Pulse pattern of PWM signal> Figures 5 to 12 are diagrams illustrating the pulse patterns of the PWM signals when the PWM generation unit 24 according to the embodiment switches between the boost mode, step-down mode, and charge / discharge operation. In Figures 5 to 12, the rectangles with diagonal lines illustrate the patterns of PWM signals with a fixed pulse width. Also, the rectangles with horizontal lines illustrate the pulse patterns of PWM signals in which the pulses move due to a phase shift. Further, the rectangles with vertical lines illustrate the pulse patterns of PWM signals with a variable pulse width due to synchronous rectification operation. Hereinafter, with reference to Figures 5 to 12, the pulse patterns of the PWM signals when the charge / discharge switching control unit 26 according to the embodiment switches between the boost mode, step-down mode, and charge / discharge operation will be described.

[0054] FIG. 5 is a first diagram illustrating a pattern of a PWM signal when the charge / discharge switching control unit 26 switches from a charging operation to a discharging operation while the upper device continues to output a step-up / step-down signal in the step-down mode in the embodiment. In the example of FIG. 5, it is assumed that the charging operation in the step-down mode is switched to a discharging operation in the step-down mode at the timing K1. Until the timing K1, the PWM generating unit 24 supplies a PWM signal to each switching element Qn (n=1 to 8) so as to perform a charging operation in the step-down mode. Then, at the timing K1, while the upper device continues to output a step-up / step-down signal in the step-down mode, the charge / discharge switching control unit 26 outputs a charge / discharge signal to the PWM generating unit 24 indicating a switch from a charging operation to a discharging operation. Having received the charge / discharge signal from the charge / discharge switching control unit 26, the PWM generating unit 24 controls each switching element Qn (n=1 to 8) so as to perform a discharging operation in the step-down mode. The PWM signal supplied to the switching element Qn (n=1 to 8) is switched.

[0055] FIG. 6 is a second diagram illustrating a pattern of a PWM signal when the charging / discharging switching control unit 26 switches from a charging operation to a discharging operation while the upper device is outputting a step-down mode step-up / step-down signal in the embodiment. In the example of FIG. 6, the charging operation in the step-down mode is switched to a discharging operation in the step-down mode at the timing of K2. FIG. 6 and FIG. 5 have different phase shift amounts after switching from the charging operation in the step-down mode to the discharging operation in the step-down mode. Until the timing K2, the PWM generating unit 24 supplies a PWM signal to each switching element Qn (n=1 to 8) so as to perform a charging operation in the step-down mode. Then, at the timing of K2, the upper device outputs a charge / discharge switching control unit 26 to the PWM generating unit 24 a charge / discharge signal indicating a switch from a charging operation to a discharging operation while outputting a step-down mode step-up / step-down signal. The PWM generating unit 24, which has received the charge / discharge signal from the charge / discharge switching control unit 26, switches the PWM signal supplied to each switching element Qn (n=1 to 8) so as to perform a discharging operation in the step-down mode.

[0056] 6, when switching from a charging operation in the step-down mode to a discharging operation in the step-down mode, as illustrated by a rectangular frame W1, it becomes impossible to ensure a dead time between the switching element Q4 before switching to the discharging operation and the switching element Q2 after switching to the discharging operation. Therefore, the PWM generating unit 24 ensures the dead time by delaying the rising timer value of the PWM signal supplied to the switching element Q2 after switching to the discharging operation.

[0057] FIG. 7 is a third diagram illustrating a pattern of a PWM signal when the charging / discharging switching control unit 26 switches from a charging operation to a discharging operation while the upper device is outputting a step-down mode signal in the embodiment. In the example of FIG. 7, the charging operation in the step-down mode is switched to a discharging operation in the step-down mode at the timing of K3. FIG. 7 and FIG. 5 have different phase shift amounts before switching from the charging operation in the step-down mode to the discharging operation in the step-down mode. Until the timing K3, the PWM generating unit 24 supplies a PWM signal to each switching element Qn (n=1 to 8) so as to perform a charging operation in the step-down mode. Then, at the timing of K3, the upper device outputs a step-up / step-down signal in the step-down mode to the PWM generating unit 24, and the charging / discharging switching control unit 26 outputs a charge / discharge signal indicating a switch from a charging operation to a discharging operation. The PWM generating unit 24, which has received the charge / discharge signal from the charge / discharge switching control unit 26, switches the PWM signal to be supplied to each switching element Qn (n=1 to 8) so as to perform a discharging operation in the step-down mode.

[0058] 7, when switching from a charging operation in the step-down mode to a discharging operation in the step-down mode, as illustrated by a rectangular frame W2, it becomes impossible to ensure a dead time between the switching element Q6 before switching to the discharging operation and the switching element Q8 after switching to the discharging operation. Therefore, the charge / discharge switching control unit 26 ensures the dead time by stopping the supply of a PWM signal to the switching element Q8 after switching to the charging operation.

[0059] FIG. 8 is a first diagram illustrating a pattern of a PWM signal when the charge / discharge switching control unit 26 switches from a discharging operation to a charging operation while the upper device continues to output a step-up / step-down signal in the step-down mode in the embodiment. In the example of FIG. 8, it is assumed that the discharging operation in the step-down mode is switched to a charging operation in the step-down mode at the timing K4. Until the timing K4, the PWM generating unit 24 supplies a PWM signal to each switching element Qn (n=1 to 8) so as to perform a discharging operation in the step-down mode. Then, at the timing K4, while the upper device continues to output a step-up / step-down signal in the step-down mode, the charge / discharge switching control unit 26 outputs a charge / discharge signal to the PWM generating unit 24 indicating a switch from a discharging operation to a charging operation. Having received the charge / discharge signal from the charge / discharge switching control unit 26, the PWM generating unit 24 switches to a charging operation in the step-down mode. , switches the PWM signal supplied to each switching element Qn (n=1 to 8).

[0060] FIG. 9 is a second diagram illustrating a pattern of a PWM signal when the charge / discharge switching control unit 26 switches from a discharging operation to a charging operation while the upper device is outputting a step-down mode step-up / step-down signal in the embodiment. In the example of FIG. 9, the discharge operation in the step-down mode is switched to a charging operation in the step-down mode at the timing of K5. FIG. 9 and FIG. 8 have different phase shift amounts after switching from a discharging operation in the step-down mode to a charging operation in the step-down mode. Until the timing K5, the PWM generating unit 24 supplies a PWM signal to each switching element Qn (n=1 to 8) so as to perform a discharging operation in the step-down mode. Then, at the timing of K5, the upper device outputs a charge / discharge signal to the PWM generating unit 24, indicating that the charge / discharge switching control unit 26 switches from a discharging operation to a charging operation while outputting a step-down mode step-up / step-down signal. The PWM generating unit 24, which has received the charge / discharge signal from the charge / discharge switching control unit 26, switches the PWM signal supplied to each switching element Qn (n=1 to 8) so as to perform a charging operation in the step-down mode.

[0061] 9, when switching from a discharging operation in the step-down mode to a charging operation in the step-down mode, as illustrated by a rectangular frame W3, it becomes impossible to ensure a dead time between the switching element Q8 before switching to the charging operation and the switching element Q6 after switching to the charging operation. Therefore, the PWM generating unit 24 ensures the dead time by delaying the rising timer value of the PWM signal supplied to the switching element Q6 after switching to the charging operation.

[0062] FIG. 10 is a second diagram illustrating a pattern of a PWM signal when the charge / discharge switching control unit 26 switches from a discharging operation to a charging operation while the upper device is outputting a step-down mode step-up / step-down signal in the embodiment. In the example of FIG. 10, the discharging operation in the step-down mode is switched to a charging operation in the step-down mode at the timing of K6. FIG. 10 and FIG. 8 have different phase shift amounts before switching from the discharging operation in the step-down mode to the charging operation in the step-down mode. Until the timing K6, the PWM generating unit 24 supplies a PWM signal to each switching element Qn (n=1 to 8) so as to perform a charging operation in the step-down mode. Then, at the timing K6, the upper device outputs a step-down mode step-up / step-down signal while the charge / discharge switching control unit 26 outputs a charge / discharge signal indicating switching from a charging operation to a discharging operation to the PWM generating unit 24. The PWM generating unit 24, which receives the charge / discharge signal from the charge / discharge switching control unit 26, switches the PWM signal to be supplied to each switching element Qn (n=1 to 8) so as to perform a discharge operation in the step-down mode.

[0063] 10, when switching from a discharging operation in the step-down mode to a charging operation in the step-down mode, as illustrated by a rectangular frame W4, it becomes impossible to ensure a dead time between the switching element Q6 before switching to the charging operation and the switching element Q8 after switching to the charging operation. Therefore, the charge / discharge switching control unit 26 ensures the dead time by stopping the supply of a PWM signal to the switching element Q8 after switching to the charging operation.

[0064] <Processing flow> 11 and 12 are diagrams showing an example of a processing flow of the charge / discharge switching processing of the power conversion device 1 according to the embodiment. Hereinafter, an example of the processing flow of the charge / discharge switching processing of the power conversion device 1 will be described with reference to FIGS. 11 and 12.

[0065] In step S1, the charge / discharge switching control unit 26 determines whether the command value output from the higher-level device is greater than 0 A, 0 A, or less than 0 A. If it is greater than 0 A ("Command value>0 A" in step S1), the process proceeds to step S2. If it is 0 A ("Command value=0 A" in step S1), the process proceeds to step S3. If it is less than 0 A ("Command value<0A" in step S1), the process proceeds to step S4.

[0066] In step S2, the charge / discharge switching control unit 26 outputs a charge / discharge signal instructing to switch to a charging operation to the PWM generating unit 24. The PWM generating unit 24 supplies a PWM signal to each switching element Qn (n=1 to 8) so as to perform a charging operation.

[0067] In step S3, the charge / discharge switching control unit 26 does not switch between the charging operation and the discharging operation, so the DC / DC converter 10 continues the previously set operation (the charging operation or the discharging operation).

[0068] In step S4, the charge / discharge switching control unit 26 outputs a charge / discharge signal instructing to switch to a discharge operation to the PWM generating unit 24. The PWM generating unit 24 supplies a PWM signal to each switching element Qn (n=1 to 8) so as to perform a discharge operation.

[0069] In step S5, the PWM generating unit 24 determines whether or not switching between the charging operation and the discharging operation has occurred in step S2 or step S4. If switching has occurred ("YES" in step S5), the process proceeds to step S6. If switching has not occurred ("NO" in step S5), the process ends.

[0070] In step S6, the PWM generating unit 24 determines whether the dead time at the rising edge of the waveform of the PWM signal is insufficient. If it is insufficient ("YES" in step S6), the process proceeds to step S7. If it is not insufficient ("NO" in step S6), the process proceeds to step S8.

[0071] In step S7, if the period from the time the switch is performed to the rising timer value is insufficient to cover the dead time, the PWM generating unit 24 delays the rising edge of the waveform until the dead time is secured, as described with reference to FIG. 3.

[0072] In step S8, the PWM generating unit 24 determines whether the dead time at the falling edge of the waveform of the PWM signal is insufficient. If it is insufficient ("YES" in step S8), the process proceeds to step S9. If it is not insufficient ("NO" in step S8), the process proceeds to step S10.

[0073] In step S9, if the period from when the switching occurs until the falling timer value is insufficient for the dead time, the PWM generating unit 24 suppresses the supply of the PWM signal as described with reference to FIG.

[0074] In step S10, the PWM generating unit 24 switches the PWM signals supplied to the full bridge circuit 11 and the full bridge circuit 12. The PWM generating unit 24 switches the PWM signals supplied to the full bridge circuit 11 and the full bridge circuit 12 using the PWM signals adjusted in the processes from steps S6 to S9.

[0075] <Effects of the embodiment> According to this embodiment, when switching from a charging operation to a discharging operation or from a discharging operation to a charging operation, the charging / discharging switching control unit 26 switches the PWM signals supplied to the full-bridge circuits 11 and 12. Therefore, according to this embodiment, it is possible to switch between the charging operation and the discharging operation without stopping the operation of the DC / DC converter 10.

[0076] In addition, in this embodiment, if the dead time is insufficient at the rising edge of the PWM signal waveform, the rising edge timer value is corrected to a value that ensures the dead time. When the dead time is insufficient at the falling edge of the PWM signal waveform, the output of the PWM signal is suppressed. Therefore, according to this embodiment, it is possible to prevent an unwanted current from flowing due to a lack of dead time when switching the PWM signals supplied to the full-bridge circuits 11 and 12.

[0077] In the present embodiment, the charging operation is switched to the discharging operation or the discharging operation is switched to the charging operation depending on the sign of the command value. Therefore, according to the present embodiment, the charging operation and the discharging operation can be flexibly switched to each other depending on the command value.

[0078] [Modifications] In the embodiment described above, the charging operation and discharging operation of the DC / DC converter 10 are switched in response to the sign of the command value. However, the charging operation and discharging operation of the DC / DC converter 10 may be switched in response to, for example, a user instruction such as buying or selling electricity, pressing a charge / discharge button on the EV 2, or the like.

[0079] In the embodiment described above, the step-up / step-down signal is input from a higher-level device, but the control unit 20 may have a step-up / step-down switching control unit that generates a step-up / step-down signal, and the step-up / step-down switching control unit may output the step-up / step-down signal to the PWM generation unit.

[0080] In the above-described embodiment, the charging operation and the discharging operation are switched when the step-down mode is switched to the step-down mode. However, the DC / DC converter 10 according to the embodiment may switch between the step-down mode and the step-up mode and may also switch between the charging operation and the discharging operation. For example, the DC / DC converter 10 may switch between the charging operation and the discharging operation together with various switching between the step-up mode and the step-down mode. In such a case, the DC / DC converter 10 may set the phase shift amount of each switching element Qn (n=1 to 8) of the full bridge circuits 11 and 12 so as to operate in a desired mode (step-up mode, step-down mode) and may replace the PWM signal supplied to the full bridge circuits 11 and 12.

[0081] In the embodiment described above, the DC / DC converter 10 is an insulated bidirectional DC / DC converter, but the disclosed technology can also be applied to a non-insulated bidirectional DC / DC converter.

[0082] The embodiments and modifications disclosed above can be combined with each other.

[0083] <Appendix 1> A first input / output terminal pair (13); A second input / output terminal pair (14); a first capacitor (C1) connected in parallel to the first input / output terminal pair; a second capacitor (C2) connected in parallel to the first input / output terminal pair; a first switching unit (11) connected to the first capacitor (C1); a second switching unit (12) connected to the second capacitor (C2); a transformer (TR) disposed between the first switching unit (11) and the second switching unit (12); a control unit (20) that switches between a charging operation in which a PWM signal of a first pattern is supplied to the first switching unit (11) and the second switching unit (12) to control the first switching unit (11) and the second switching unit (12) to output a current from the first input / output terminal pair (13) and a discharging operation in which a PWM signal of a second pattern is supplied to the first switching unit (11) and the second switching unit (12) to control the first switching unit (11) and the second switching unit (12) to output a current from the second input / output terminal pair (14), The control unit (20) changes the first switch in response to a change in a command received from a higher-level device. a PWM signal supplied to the first switching unit (11) and a PWM signal supplied to the second switching unit (12) are interchanged to switch between the charging operation and the discharging operation. Power conversion equipment. <Appendix 2> When the period from switching the discharging operation and the charging operation to the rising edge of the PWM signal becomes less than a predetermined period (dead time) when the PWM signal is switched, the control unit (20) delays the rising edge of the PWM signal whose period until the rising edge becomes less than the predetermined period (dead time). The power conversion device (1) as described in appendix 1. <Appendix 3> When the period from switching between the discharging operation and the charging operation to the falling edge of the PWM signal becomes less than a predetermined period (dead time) when the PWM signal is switched, the control unit (20) suppresses the supply of the PWM signal whose period until the falling edge becomes less than the predetermined period (dead time). The power conversion device (1) according to appendix 1 or 2. <Appendix 4> The control unit (20) when receiving from the upper device a first step-down signal instructing a first step-down mode in which a first voltage input to the first input / output terminal pair (13) is stepped down to a second voltage output from the second input / output terminal pair (14), setting a first phase shift amount of the first switching unit (11) and the second switching unit (12) so as to follow the step-down signal; when receiving, after receiving the first step-down signal, a second step-down signal instructing a second step-down mode in which a first voltage input to the first input / output terminal pair (13) is stepped down to a third voltage output from the second input / output terminal pair (14) from the higher-level device, a second phase shift amount of the first switching unit (11) and the second switching unit (12) is set so as to follow the second step-down signal, and a PWM signal supplied to the first switching unit (11) and a PWM signal supplied to the second switching unit (12) are interchanged; 4. A power conversion device according to any one of claims 1 to 3. <Appendix 5> The control unit (20) when receiving a boost signal from the higher-level device instructing a boost mode in which a first voltage input to the first input / output terminal pair (13) is boosted to a second voltage output from the second input / output terminal pair (13), setting a first phase shift amount of the first switching unit (11) and the second switching unit (12) so as to follow the boost signal; after receiving the boost signal, when a step-down signal instructing a step-down mode in which a first voltage input to the first input / output terminal pair (13) is stepped down to a fourth voltage output from the second input / output terminal pair (14) is received from the higher-level device and the command is changed, second phase shift amounts of the first switching unit (11) and the second switching unit (12) are set so as to follow the step-down signal, and a PWM signal supplied to the first switching unit (11) and a PWM signal supplied to the second switching unit (12) are interchanged; 4. A power conversion device according to any one of claims 1 to 3. <Appendix 6> The control unit (20) when receiving a step-down signal from the upper device instructing a step-down mode in which a first voltage input to the first input / output terminal pair (13) is stepped down to a second voltage output from the second input / output terminal pair (14), setting a first phase shift amount of the first switching unit (11) and the second switching unit (12) so as to follow the step-down signal; After receiving the step-down signal, a step-up signal is received from the upper device, the step-up signal instructing a step-up mode in which a first voltage input to the first input / output terminal pair (13) is boosted to a fifth voltage output from the second input / output terminal pair (14) and when the command is changed, the step-up signal is followed. and setting a second phase shift amount of the first switching unit (11) and the second switching unit (12) so that the second phase shift amount of the first switching unit (11) and the second switching unit (12) are switched over between the PWM signal supplied to the first switching unit (11) and the PWM signal supplied to the second switching unit (12). 4. A power conversion device according to any one of claims 1 to 3. <Appendix 7> The control unit (20) when receiving from the higher-level device a first boost signal instructing a first boost mode in which a first voltage input to the first input / output terminal pair (13) is boosted to a sixth voltage output from the second input / output terminal pair (14), setting a first phase shift amount of the first switching unit (11) and the second switching unit (12) so as to follow the first boost signal; when, after receiving the first boost signal, a second boost signal instructing a second boost mode in which a first voltage input to the first input / output terminal pair (13) is boosted to a seventh voltage output from the second input / output terminal pair (14) is received from the higher-level device and the command is changed, second phase shift amounts of the first switching unit (11) and the second switching unit (12) are set so as to follow the second boost signal, and a PWM signal supplied to the first switching unit (11) and a PWM signal supplied to the second switching unit (12) are interchanged; 4. A power conversion device according to any one of claims 1 to 3. [Explanation of symbols]

[0084] 1. Power conversion device 2··EV 3...Power system 4. Load 10. DC / DC converter 11. Full bridge circuit 12. Full bridge circuit 20. Control unit 23 Control section 24...PWM generation section 26 Charge / discharge switching control unit 30. Inverter 13 Input / Output Terminal Pair 14 Input / Output Terminal Pair 13p Input / output terminal 13m...Input / output terminal 14p Input / output terminal 14m...Input / output terminal C1 Capacitor C2 Capacitor TR··Transformer Lr1 Reactor Lr2 Reactor Q1 Switching element Q2 Switching element Q3 Switching element Q4 Switching element Q5 Switching element Q6 Switching element Q7 Switching element Q8 Switching element

Claims

1. a first input / output terminal pair; A second input / output terminal pair; a first capacitor connected in parallel to the first input / output terminal pair; a second capacitor connected in parallel to the second input / output terminal pair; a first switching unit connected to the first capacitor; a second switching unit connected to the second capacitor; A transformer disposed between the first switching unit and the second switching unit; a control unit that switches between a charging operation in which a PWM signal of a first pattern is supplied to the first switching unit and the second switching unit to control the first switching unit to output a current from the first input / output terminal pair, and a discharging operation in which a PWM signal of a second pattern is supplied to the first switching unit and the second switching unit to control the second switching unit to output a current from the second input / output terminal pair, The control unit switches between the charging operation and the discharging operation by replacing a PWM signal supplied to the first switching unit and a PWM signal supplied to the second switching unit in response to a change in a command received from a higher-level device. Power conversion equipment.

2. When the period from switching the discharging operation and the charging operation to the rising edge of the PWM signal becomes less than a predetermined period when the PWM signal is switched, the control unit delays the rising edge of the PWM signal whose period until the rising edge becomes less than the predetermined period. The power conversion device according to claim 1 .

3. When the PWM signal is switched, the control unit suppresses the supply of the PWM signal whose period until the falling edge is shorter than the predetermined period from the switching between the discharging operation and the charging operation. The power conversion device according to claim 1 .

4. The control unit is when receiving from the upper device a first step-down signal instructing a first step-down mode in which a first voltage input to the first input / output terminal pair is stepped down to a second voltage output from the second input / output terminal pair, setting a first phase shift amount of the first switching unit and the second switching unit so as to follow the first step-down signal; when receiving, after receiving the first step-down signal, a second step-down signal instructing a second step-down mode in which a first voltage input to the first input / output terminal pair is stepped down to a third voltage output from the second input / output terminal pair from the upper device, second phase shift amounts of the first switching unit and the second switching unit are set so as to follow the second step-down signal, and a PWM signal supplied to the first switching unit and a PWM signal supplied to the second switching unit are interchanged; The power conversion device according to claim 1 .

5. The control unit is when receiving a boost signal from the upper device instructing a boost mode in which a first voltage input to the first input / output terminal pair is boosted to a second voltage output from the second input / output terminal pair, setting a first phase shift amount of the first switching unit and the second switching unit so as to follow the boost signal; a step-down signal instructing a step-down mode in which a first voltage input to the first input / output terminal pair is stepped down to a fourth voltage output from the second input / output terminal pair after receiving the step-up signal; When the command is received from a higher-level device and is changed, a second phase shift amount of the first switching unit and the second switching unit is set so as to follow the step-down signal, and the PWM signal supplied to the first switching unit and the PWM signal supplied to the second switching unit are replaced. The power conversion device according to claim 1 .

6. The control unit is when receiving a step-down signal from the upper device instructing a step-down mode in which a first voltage input to the first input / output terminal pair is stepped down to a second voltage output from the second input / output terminal pair, setting a first phase shift amount of the first switching unit and the second switching unit in accordance with the step-down signal; after receiving the step-down signal, a step-up signal instructing a step-up mode in which a first voltage input to the first input / output terminal pair is boosted to a fifth voltage output from the second input / output terminal pair is received from the upper device and when the command is changed, second phase shift amounts of the first switching unit and the second switching unit are set so as to follow the step-up signal, and a PWM signal supplied to the first switching unit and a PWM signal supplied to the second switching unit are interchanged; The power conversion device according to claim 1 .

7. The control unit is when receiving from the upper device a first boost signal instructing a first boost mode in which a first voltage input to the first input / output terminal pair is boosted to a sixth voltage output from the second input / output terminal pair, setting a first phase shift amount of the first switching unit and the second switching unit so as to follow the first boost signal; when, after receiving the first boost signal, a second boost signal instructing a second boost mode in which a first voltage input to the first input / output terminal pair is boosted to a seventh voltage output from the second input / output terminal pair is received from the higher-level device and the command is changed, second phase shift amounts of the first switching unit and the second switching unit are set to follow the second boost signal, and a PWM signal supplied to the first switching unit and a PWM signal supplied to the second switching unit are interchanged; The power conversion device according to claim 1 .

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