Power conversion device

Abstract

Provided is a power conversion device capable of suppressing ripple (fluctuation) of voltage and current. A power conversion device (10) is provided with a first switch unit (11) and a second switch unit (13), a transformer unit (15), and a control device (29). Each of the switching units (11, 13) is provided with a plurality of switching elements provided on a high-side arm on the positive electrode side and a low-side arm on the negative electrode side. The transformer section (15) is provided with a first coil (15a) connected to the first switch section (11) and a second coil (15b) connected to the second switch section (13). The control device (29) sets a predetermined rest time (Ti) between a pulse instructing the driving of the switching element of the high-side arm of each of the switching units (11, 13) and a pulse instructing the driving of the switching element of the low-side arm of each of the switching units (11, 13).

Description

Technical Field

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

[0002] In recent years, efforts to realize a low-carbon society or a decarbonized society have become more active, and research and development related to electrification technology is being carried out in order to reduce CO2 emissions and improve energy efficiency in vehicles.

[0003] Conventionally, there is known a control device for controlling the waveform of an output voltage by PNM (Pulse Number Modulation) control of a voltage control pulse in a so-called LLC resonant converter (for example, refer to Patent Document 1).

[0004] Conventionally, it is known that in an LLC resonant converter, a controller is used to set the cutoff time for a series of actions according to the current on the primary side in order to intermittently perform a series of actions in which the high-side arm and the low-side arm are alternately turned on and off continuously and repeatedly (for example, refer to Patent Document 2).

[0005] Conventionally, there is known a controller that suppresses a rise in output voltage by increasing the dead time of the high-side arm and the low-side arm (ie, reducing the on-duty ratio) when starting the LLC resonant converter (for example, see Patent Document 3).

[0006] [Prior technical literature]

[0007] [Patent Literature]

[0008] Patent Document 1: Japanese Patent Application Publication No. 2022-187851

[0009] Patent Document 2: Japanese Patent Application No. 2020-507296

[0010] Patent Document 3: Japanese Patent Application Publication No. 2015-208170 Summary of the invention

[0011] Problems to be solved by the invention

[0012] However, in technologies related to electrification, the problem is to suppress the ripple (variation) of the output voltage and output current of the power conversion device. For example, in the LLC resonant converter of the above-mentioned prior art, when the high-side arm and the low-side arm are continuously turned on and off alternately, the ripple voltage and ripple current increase due to the so-called transient characteristics of the LLC resonant circuit.

[0013] Furthermore, when the output of the voltage control pulse is not in a steady state as in the PNM control of the above-mentioned conventional technology, there arises a problem that the fluctuation of the output voltage increases.

[0014] In addition, when the high-side arm and the low-side arm are continuously turned on and off intermittently as in the above-mentioned conventional technology, although temporary power reduction can be achieved, there is a problem that it cannot appropriately cope with continuously changing voltage and load.

[0015] Furthermore, when the temporarily increased dead time is reduced over time as in the above-mentioned conventional technology, for example, a situation in which the output current is continuously and arbitrarily changed cannot be appropriately handled, and problems such as heat generation due to resonance deviation may occur.

[0016] In order to solve the above-mentioned problems, the present application aims to suppress the ripple (variation) of voltage and current, and further contribute to the development of a sustainable transmission system.

[0017] Solutions to Solve Problems

[0018] In order to solve the above problems and achieve the above objects, the present invention adopts the following means.

[0019] (1): A power conversion device according to one embodiment of the present invention (for example, the power conversion device 10 in the embodiment) comprises: a first switching unit (for example, the first switching unit 11 in the embodiment) and a second switching unit (for example, the second switching unit 13 in the embodiment), which have a plurality of switching elements (for example, the transistors 11a, 11b, 13a, 13b in the embodiment) provided on a high-side arm on a positive pole side and a low-side arm on a negative pole side; a transformer unit (for example, the transformer unit 15 in the embodiment), which has a first coil (for example, the first coil 15a in the embodiment) connected to the first switching unit and a second coil (for example, the second coil 15b in the embodiment) connected to the second switching unit; and a control unit (for example, the control device 29 in the embodiment), which sets a prescribed rest time (for example, the prescribed rest time Ti in the embodiment) between a pulse indicating the drive of the switching element of the high-side arm and a pulse indicating the drive of the switching element of the low-side arm.

[0020] (2): Based on the power conversion device described in (1) above, the control unit may set the specified rest time based on at least the output side current target value (for example, the secondary side current target value in the embodiment) and the input side voltage detection value (for example, the primary side voltage detection value in the embodiment).

[0021] (3): In the power conversion device described in (2) above, the control unit may set the predetermined idle time based on an output side voltage detection value (for example, a secondary side voltage detection value in the embodiment).

[0022] (4): Based on the power conversion device described in any one of (1) to (3) above, the power conversion device may include a changing unit (for example, the winding ratio changing unit 17 in the embodiment), which changes the winding ratio of the transformer unit, and the control unit controls the output based on the resonance obtained by the excitation inductance of the transformer unit, the leakage inductance of the first coil, and the capacitor connected in series with the first coil, or based on the resonance obtained by the excitation inductance of the transformer unit, the inductance connected in series with the first coil, and the capacitor connected in series with the first coil.

[0023] (5): Based on the power conversion device described in (4) above, the control unit may relatively reduce the width of the pulse in the power conversion from the second switching unit to the first switching unit compared to the width of the pulse in the power conversion from the first switching unit to the second switching unit.

[0024] (6): Based on the power conversion device described in (5) above, the power conversion device may also include: a power supply connected to the first switch unit; and an AC load (for example, load 27 in the embodiment) connected to the second switch unit, and the control unit controls the power transfer of the AC load.

[0025] Effects of the Invention

[0026] According to the above (1), the output current can be made variable by providing a control unit for setting a predetermined idle time, which is different from the dead time for preventing a short circuit between the high-side arm and the low-side arm, etc. Compared with a case where the predetermined idle time is not set and continuous switching is performed, it is possible to suppress an increase in ripples (variations) in the output voltage and the output current, and suppress a decrease in the efficiency of power conversion.

[0027] In the case of (2) above, the density of the number of pulses per unit time can be controlled by using the prescribed rest time, and the output waveform can be precisely controlled according to the resolution of the pulse interval. The output current can be arbitrarily changed from zero according to the output side current target value and the input side voltage detection value, and AC output can be performed in addition to DC output.

[0028] In the case of (3) above, the predetermined rest time according to the output current target value and the input voltage detection value can be appropriately corrected by, for example, nonlinear correction based on the output voltage detection value.

[0029] In the case of (4) above, by providing a changing unit that changes the winding ratio of the transformer unit, bidirectional power conversion can be performed in a so-called LLC resonant converter in a boost mode.

[0030] In the case of (5) above, even when the ripple (variation) of the output voltage and the output current increases due to the change in the winding ratio of the transformer, the increase in the ripple (variation) can be suppressed by reducing the pulse width.

[0031] In the case of (6) above, the driving and regeneration of the AC load can be appropriately controlled. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a configuration diagram of a power conversion device according to an embodiment of the present invention.

[0033] Figure 2 This is a diagram showing an example of a pulse for instructing driving of each switching element of the high-side arm and the low-side arm when the power conversion device according to the embodiment of the present invention operates.

[0034] Figure 3 This is a diagram showing an example of the relationship between the secondary side voltage and the pulses instructing driving of the switching elements of the high-side arm and the low-side arm during operation of the power conversion device in the comparative example of the embodiment of the present invention.

[0035] Figure 4 This is a diagram showing an example of the relationship between the transformer current and the pulses instructing driving of the switching elements of the high-side arm and the low-side arm during operation of the power conversion device in the comparative example of the embodiment of the present invention.

[0036] Figure 5 This is a flowchart showing the operation when the power conversion device according to the embodiment of the present invention supplies power from the power supply side to the load side (in the driving mode).

[0037] Figure 6 This is a diagram showing an example of the relationship between the secondary side current and the duty ratio (DUTY) in the power conversion device according to the embodiment of the present invention.

[0038] Figure 7 This is a diagram showing an example of the relationship between the duty ratio (DUTY) during operation of the power conversion device according to the embodiment of the present invention, a pulse indicating driving of each switching element of the high-side arm and the low-side arm, a secondary-side current, and a secondary-side voltage.

[0039] Figure 8 This is a flowchart showing the operation when the power conversion device according to the embodiment of the present invention supplies electric power from the load side to the power supply side (in the regeneration mode).

[0040] Fig. 9This is a diagram showing an example of the relationship between the pulses and pulse widths indicating the drive of the switching elements of the high-side arm and the low-side arm, the secondary-side current, and the secondary-side voltage when power is supplied from the load side to the power supply side (in regeneration mode) by the power conversion device according to an embodiment of the present invention.

[0041] Description of reference numerals:

[0042] 10…power conversion device, 11…first switch unit, 11a, 11b…transistor (switching element), 13…second switch unit, 13a, 13b…transistor (switching element), 15…voltage transformation unit, 15a…first coil, 15b…second coil, 17…winding ratio changing unit (changing unit), 19a…inductor, 19b…capacitor, 21…power supply, 23…first capacitor, 25…second capacitor, 27…load (AC load), 29…control device (control unit). DETAILED DESCRIPTION

[0043] Hereinafter, a power conversion device according to an embodiment of the present invention will be described with reference to the drawings.

[0044] Figure 1 It is a configuration diagram of the power conversion device 10 according to the embodiment.

[0045] The power conversion device 10 of the embodiment is mounted on, for example, an electric vehicle, an electric mobile body, an electric machine, a power supply device, and various electrical equipment. Examples of electric vehicles include electric vehicles having a motor driven by the power of a battery as a power source, straddle-type vehicles and scooters, hybrid vehicles based on a combination of a motor and an internal combustion engine, and fuel cell vehicles based on a combination of a battery and a fuel cell. Examples of electric mobile bodies include mobile working machines, robots, flying objects, and mobile bodies on and in water. Examples of electric machines include construction machinery and mobile working machines having a motor as a power source. Examples of power supply devices include fixed-type or mobile power supply devices that discharge and charge batteries.

[0046] like Figure 1 As shown, the power conversion device 10 of the embodiment is a so-called bidirectional LLC resonant converter. The power conversion device 10 includes, for example, a first switching unit 11 and a second switching unit 13, a transformer 15, a winding ratio changer 17, and a resonant inductor 19a and a capacitor 19b.

[0047] The first switch section 11 and the second switch section 13 each include a bridge circuit formed by a plurality of switch elements connected in a two-phase bridge, for example. Each switch element is, for example, a transistor such as a MOSFET (Metal Oxide Semi-conductor Field Effect Transistor) of SiC (Silicon Carbide). The plurality of switch elements of the first switch section 11 are transistors 11a and 11b of the high-side arm and the low-side arm of each phase. The plurality of switch elements of the second switch section 13 are transistors 13a and 13b of the high-side arm and the low-side arm of each phase. Each transistor 11a, 11b, 13a, 13b includes a body diode D and a capacitor C corresponding to a parasitic capacitance or a total capacitance of a parasitic capacitance and a capacitance of an external capacitor arranged in parallel with the body diode D.

[0048] The first switching unit 11 and the second switching unit 13 function as a combination of a rectangular wave generating circuit and a rectifying and outputting circuit, for example.

[0049] The transformer 15 includes, for example, a first coil 15a connected to the first switch 11 and a second coil 15b connected to the second switch 13. The first coil 15a and the second coil 15b are magnetically coupled to each other with the same polarity.

[0050] The winding ratio changing unit 17 includes, for example, a tap (terminal) provided at a predetermined position of the second coil 15b of the transformer unit 15, and a switching mechanism for selectively connecting or switching the tap of the second coil 15b. The switching mechanism includes, for example, a plurality of switching elements. The winding ratio changing unit 17 switches, for example, the winding ratio of the transformer unit 15 (= the number of turns of the first coil 15a / the number of turns of the second coil 15b) so that the power conversion device 10 operates in the boost mode. The boost mode is an operation mode in which the input-output voltage ratio (= output voltage / input voltage) is greater than 1.

[0051] The winding ratio changing unit 17 and the second coil 15 b of the transformer unit 15 are connected in series between the connection point of the high-side arm and the low-side arm of the two phases of the second switch unit 13 .

[0052] The resonant inductor 19a is, for example, an inductor corresponding to the leakage inductance of the first coil 15a of the transformer unit 15 or an inductor connected in series with the first coil 15a of the transformer unit 15.

[0053] The resonance capacitor 19 b is, for example, a capacitor connected in series with the first coil 15 a of the transformer unit 15 .

[0054] The resonant inductor 19 a and capacitor 19 b are connected in series with the first coil 15 a of the transformer unit 15 between the connection points of the high-side arm and the low-side arm of the two phases of the first switch unit 11 .

[0055] The magnetizing inductance of the transformer 15, the inductance of the inductor 19a, and the capacitance of the capacitor 19b function as a series resonant circuit (LLC resonant circuit).

[0056] The power conversion device 10 includes, for example, a power supply 21 , a first capacitor 23 , a second capacitor 25 , a load 27 , and a control device 29 .

[0057] The power source 21 is, for example, a power storage device based on a storage battery such as a lithium ion storage battery.

[0058] The first capacitor 23 and the second capacitor 25 are capacitors for voltage smoothing. The first capacitor 23 is connected in parallel to the power source 21 and the positive and negative electrodes of the first switch unit 11. The second capacitor 25 is connected in parallel to the positive and negative electrodes of the second switch unit 13 and the load 27.

[0059] The load 27 is a so-called DC load or an AC load.

[0060] The control device 29 is a software function unit that performs functions by executing a predetermined program by a processor such as a CPU (Central Processing Unit). The software function unit is an ECU that includes a processor such as a CPU, a ROM (Read Only Memory) for storing programs, a RAM (Random Access Memory) for temporarily storing data, and electronic circuits such as a timer. It should be noted that at least a part of the control device 29 may also be an integrated circuit such as an LSI (Large Scale Integration).

[0061] For example, the control device 29 includes a current sensor for detecting current and a voltage sensor for detecting voltage of each of the first switching unit 11 and the second switching unit 13. The control device 29 controls the power conversion device 10 based on signals of current detection values ​​and voltage detection values ​​outputted from the current sensor and the voltage sensor.

[0062] Hereinafter, the operation of the power conversion device 10 in the embodiment will be described.

[0063] For example, the control device 29 controls the winding ratio of the transformer 15 through the winding ratio changing unit 17 in order to perform the step-up mode operation. In the driving mode for supplying power from the power source 21 to the load 27, the control device 29 does not select the tap of the second coil 15b, but sets it so that the number of turns of the first coil 15a is relatively smaller than the number of turns of the second coil 15b. In the regeneration mode for supplying power from the load 27 to the power source 21, the control device 29 selects the tap of the second coil 15b and sets it so that the number of turns of the first coil 15a is relatively larger than the number of turns of the second coil 15b.

[0064] The control device 29 controls the transfer of electric power between the power source 21 and the load 27 by instructing the switching of each switching element of the first switching unit 11 and the second switching unit 13 to turn on (conduct) and turn off (disconnect).

[0065] For example, the control device 29 controls each switching element of the first switching unit 11 and the second switching unit 13 by using soft switching of so-called zero voltage switching (ZVS). In zero voltage switching (ZVS), each switching element is turned on (switched from the off state to the on state) after the voltage across both ends becomes zero due to the discharge of the output capacity (parasitic capacity) in the off state during the dead time of each phase.

[0066] Figure 2 1 is a diagram showing an example of a pulse for instructing driving of each switching element of the high-side arm and the low-side arm during operation of the power conversion device 10 according to the embodiment.

[0067] like Figure 2 As shown, the control device 29 sets a specified rest time Ti between the connection (conduction) of the high-side arm and the connection (conduction) of the low-side arm in addition to the dead time set for preventing short circuits between the high-side arm and the low-side arm in each switch unit 11, 13 and zero voltage switching (ZVS).

[0068] For example, the control device 29 sets the prescribed rest time Ti based on at least the current target value on the second switch unit 13 side and the voltage detection value on the first switch unit 11 or the second switch unit 13 side, which is the input side, in each of the driving mode and the regeneration mode. The control device 29 may set the prescribed rest time Ti based on the voltage detection value on the first switch unit 11 or the second switch unit 13 side, which is the output side, in addition to the current target value on the second switch unit 13 side and the voltage detection value on the input side.

[0069] Figure 3 This is a diagram showing an example of the relationship between the secondary side voltage and the pulses instructing driving of the switching elements of the high side arm and the low side arm during operation of the power conversion device in the comparative example of the embodiment. Figure 4 This is a diagram showing an example of the relationship between the transformer current (secondary current) and the pulses indicating the driving of the switching elements of the high-side arm and the low-side arm when the power conversion device in the comparative example of the embodiment is in operation. For example, the power conversion device in the comparative example has the same structure as the power conversion device 10 of the embodiment.

[0070] Think Figure 3 and Figure 4As in the comparative example shown, when a prescribed idle time Ti is not provided between the connection (conduction) of the high-side arm and the connection (conduction) of the low-side arm, the high-side arm and the low-side arm are continuously connected (conducted), thereby increasing the ripple (variation) of the secondary voltage and the secondary current.

[0071] In contrast to these comparative examples, the control device 29 of the embodiment provides a predetermined idle time Ti to suppress the resonance generated during the transition of the LLC resonant circuit, thereby suppressing the increase of the ripple voltage and the ripple current.

[0072] Figure 5 This is a flowchart showing the operation when the power conversion device 10 according to the embodiment supplies electric power from the power source 21 to the load 27 (in the driving mode). Figure 6 1 is a diagram showing an example of the relationship between the secondary side current and the duty ratio (DUTY) in the power conversion device 10 according to the embodiment.

[0073] like Figure 5 As shown, first, the control device 29 obtains a current target value (secondary side current target value) on the side of the second switching unit 13 serving as the output side (step S01 ).

[0074] Next, the control device 29 obtains the voltage detection value (primary side voltage detection value) on the first switch unit 11 side serving as the input side and the voltage detection value (secondary side voltage detection value) on the second switch unit 13 side serving as the output side (step S02 ).

[0075] Next, the control device 29 obtains the so-called duty ratio (DUTY) based on the secondary side current target value, the primary side voltage detection value and the secondary side voltage detection value, for example, with reference to a predetermined map obtained in advance (step S03). The duty ratio (DUTY) is, for example, the duty ratio of the pulse that instructs the switching element of each of the high side arm and the low side arm to be turned on (conducted).

[0076] like Figure 6 As shown, the secondary current and the primary voltage each have a linear correspondence with respect to the duty ratio (DUTY). The control device 29 performs a mapping search based on at least the secondary current and the primary voltage, and performs a correction such as nonlinearity based on the secondary voltage detection value, thereby obtaining the duty ratio (DUTY).

[0077] Next, the control device 29 obtains the predetermined rest time Ti based on the duty ratio (DUTY) using the following equation (1) and the following equation (2) (step S04 ).

[0078] As shown in the following mathematical formula (1), the duty ratio (DUTY) is expressed by the width (pulse width) Tp of the pulse indicating the turning-on (conduction) of the high-side arm and the low-side arm, and the predetermined rest time Ti. The pulse width Tp is, for example, a predetermined fixed value corresponding to the circuit constant of the LLC resonant circuit in the driving mode. For example, the control device 29 sets the pulse width Tp such that soft switching of so-called zero current switching (ZCS) is performed by setting a switching frequency corresponding to the resonant frequency of the LLC resonant circuit.

[0079] Based on the following mathematical formula (1), as shown in the following mathematical formula (2), the predetermined rest time Ti is expressed by the duty ratio (DUTY) and the pulse width Tp.

[0080]

[0081]

[0082] Next, the control device 29 outputs a pulse for instructing the high-side arm and the low-side arm of the first switch unit 11 to be turned on (conducted) according to the predetermined idle time Ti (step S05 ). Then, the control device 29 ends the process.

[0083] As shown in the above equation (1), the duty ratio (DUTY) corresponds to the density of the number of pulses per unit time and changes according to the predetermined idle time Ti. The control device 29 changes the duty ratio (DUTY) arbitrarily by, for example, changing the predetermined idle time Ti.

[0084] Figure 7 It is a diagram showing an example of the relationship between the duty ratio (DUTY) during operation of the power conversion device 10 in the embodiment, pulses (solid line and dotted line) indicating the driving of the switching elements of the high-side arm and the low-side arm, the secondary-side current, and the secondary-side voltage.

[0085] like Figure 7 As shown, for example, when the secondary side voltage is fixed to a specified voltage Va, the duty cycle (DUTY) changes to a first duty cycle D1, a second duty cycle D2 (>D1) and a third duty cycle D3 (>D2) according to a specified rest time Ti, and the secondary side current changes to a first current I1, a second current I2 (>I1) and a third current I3 (>I2).

[0086] For example, the control device 29 arbitrarily changes the output current from zero according to the predetermined rest time Ti, thereby performing AC output in addition to DC output.

[0087] Figure 8This is a flowchart showing the operation when the power conversion device 10 according to the embodiment supplies electric power from the load 27 side to the power source 21 side (in the regeneration mode). Fig. 9 This is a diagram showing an example of the relationship between the pulses and pulse widths indicating the drive of the switching elements of the high-side arm and the low-side arm, the secondary-side current, and the secondary-side voltage when power is supplied from the load 27 side to the power supply 21 side (in the regeneration mode) by the power conversion device 10 of the embodiment.

[0088] like Figure 8 As shown, in the case of the regeneration mode, first, the control device 29 obtains a current target value (secondary side current target value) on the second switching unit 13 side serving as the input side (step S11).

[0089] Next, the control device 29 obtains the voltage detection value (primary side voltage detection value) on the first switch unit 11 side serving as the output side and the voltage detection value (secondary side voltage detection value) on the second switch unit 13 side serving as the input side (step S12 ).

[0090] Next, the control device 29 acquires the duty ratio (DUTY) by referring to a predetermined map acquired in advance, for example, based on the secondary-side current target value, the primary-side voltage detection value, and the secondary-side voltage detection value (step S13 ).

[0091] Next, the control device 29 obtains the specified rest time Ti based on the duty ratio (DUTY) and the specified pulse width Tp corresponding to the circuit constant of the LLC resonant circuit by using the above-mentioned mathematical formula (1) and the above-mentioned mathematical formula (2) in the same manner as in the above-mentioned driving mode (step S14).

[0092] Next, the control device 29 acquires a new pulse width Tp as needed based on the current direction and duty ratio (DUTY) of the secondary-side current (step S15 ).

[0093] For example Fig. 9 As shown, in the regeneration mode, especially when the density of the number of pulses per unit time is small, even if the duty ratio (DUTY) is the same, the larger the pulse width, the greater the ripple (variation) of the secondary voltage and secondary current. Fig. 9 In the first pulse width W1 shown, it is considered that the ripples (variations) of the secondary side voltage and the secondary side current increase compared with the smaller second pulse width W2 (< W1 ).

[0094] For example, when the duty ratio (DUTY) is less than a predetermined value or as the duty ratio (DUTY) decreases, the control device 29 changes the pulse width Tp to decrease from a predetermined value corresponding to a circuit constant of the LLC resonant circuit, and obtains a new pulse width Tp.

[0095] Next, the control device 29 outputs a pulse for instructing the high-side arm and the low-side arm of the second switch unit 13 to be turned on (conducted) according to the prescribed rest time Ti and the pulse width Tp (step S16). It should be noted that the control device 29 may also change the prescribed rest time Ti obtained in the above step S14 according to the duty ratio (DUTY) and the new pulse width Tp in order to maintain the same duty ratio (DUTY) when a new pulse width Tp is obtained in the above step S15. Then, the control device 29 ends the process.

[0096] As described above, according to the power conversion device 10 of the embodiment, the control device 29 can make the output current variable by setting the predetermined idle time Ti, for example, separately from the dead time for preventing a short circuit between the high-side arm and the low-side arm, etc. Compared with the case where the predetermined idle time Ti is not set and continuous switching is performed, it is possible to suppress the increase of the ripple (variation) of the output voltage and the output current, and suppress the reduction of the efficiency of power conversion.

[0097] The control device 29 can control the density of the number of pulses per unit time by using the predetermined rest time Ti, and can precisely control the output waveform according to the resolution of the pulse interval. The output current can be arbitrarily changed from zero according to the secondary side current target value and the primary side voltage detection value, and can perform AC output in addition to DC output.

[0098] The control device 29 can appropriately correct the predetermined rest time Ti according to the secondary-side current target value and the primary-side voltage detection value by, for example, performing nonlinear correction based on the secondary-side voltage detection value.

[0099] By providing the winding ratio changing unit 17 for changing the winding ratio of the transformer unit 15 , it is possible to perform bidirectional power conversion in a boost mode in a so-called LLC resonant converter.

[0100] In the regeneration mode, even if the ripple (variation) of the output voltage and the output current increases due to the change in the winding ratio of the transformer 15, the increase in the ripple (variation) can be suppressed by reducing the pulse width Tp.

[0101] The embodiments of the present invention are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and changes can be made without departing from the scope of the invention. These embodiments, their variations, and the scope and purpose of the invention are also included in the invention recorded in the technical solution and its equivalent scope.

Claims

1. A power conversion device, wherein: The power conversion device comprises: A first switch section and a second switch section, each having a plurality of switch elements provided on a high-side arm on a positive electrode side and a low-side arm on a negative electrode side; a transformer having a first coil connected to the first switch portion and a second coil connected to the second switch portion; as well as The control unit sets a predetermined pause time between a pulse for instructing driving of the switching element of the high-side arm and a pulse for instructing driving of the switching element of the low-side arm.

2. The power conversion device according to claim 1, wherein: The control unit sets the predetermined pause time based on at least an output-side current target value and an input-side voltage detection value.

3. The power conversion device according to claim 2, wherein: The control unit sets the predetermined rest time according to an output side voltage detection value.

4. The power conversion device according to any one of claims 1 to 3, wherein: The power conversion device includes a changing unit that changes a winding ratio of the transformer unit. The control unit controls the output based on the resonance obtained through the excitation inductance of the transformer unit, the leakage inductance of the first coil, and the capacitor connected in series with the first coil, or based on the resonance obtained through the excitation inductance of the transformer unit, the inductance connected in series with the first coil, and the capacitor connected in series with the first coil.

5. The power conversion device according to claim 4, wherein: The control unit makes the width of the pulse in power conversion from the second switching unit to the first switching unit relatively smaller than the width of the pulse in power conversion from the first switching unit to the second switching unit.

6. The power conversion device according to claim 5, wherein: The power conversion device comprises: a power source connected to the first switch unit; and an AC load connected to the second switch unit, The control unit controls power transfer of the AC load.

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