WO2023105968A1

WO2023105968A1 - Power conversion device

Info

Publication number: WO2023105968A1
Application number: PCT/JP2022/039871
Authority: WO
Inventors: 翔吾廣田; 賢治花村
Original assignee: パナソニックＩｐマネジメント株式会社
Priority date: 2021-12-06
Filing date: 2022-10-26
Publication date: 2023-06-15
Also published as: JP2023084037A

Abstract

In a dual active bridge (DAB) converter, a control circuit 13 has: a first operation mode that performs control so as to include a transmission state in which a first bridge circuit 11 energizes a first DC part and a primary winding n1 of an insulated transformer TR1, and a second bridge circuit 12 energizes a secondary winding n2 of the insulated transformer TR1 together with second DC parts E2, Cb, and a commutation state in which both ends of the primary winding n1 are short circuited in the first bridge circuit 11, and the second bridge circuit 12 energizes the secondary winding n2 together with the secondary DC parts; a second operation mode that performs control so as to include the transmission state and an accumulation state in which the first bridge circuit energizes the primary winding together with the DC part, and both ends of the secondary wiring are short circuited in the second bridge circuit; and a third operation mode that performs control so as to include the transmission state, accumulation state, and commutation state.

Description

power converter

The present invention relates to a power converter that converts DC power into DC power of another voltage.

Power conditioners used in photovoltaic power generation systems and V2H (Vehicle to Home) systems are required to have highly efficient power conversion. The V2H system can charge and discharge between the storage battery installed in the EV/PHEV and the power source/load in the home. For example, an EV/PHEV can be charged with power generated by a home solar power generation system. In addition, the storage battery installed in the EV/PHEV can be used for peak shift of domestic load and for backup purposes. In addition to high efficiency, the DC/DC converters used in V2H systems are required to have a wide voltage range and isolation. One DC/DC converter that meets these requirements is a DAB (Dual Active Bridge) converter.

In a DAB converter, regardless of whether it is a phase shift method (for example, Patent Document 1) or a PWM (Pulse Width Modulation) method, the amount of power consumed varies between the step-down operation and the step-up operation with respect to the change in the control operation amount. A dead period (dead band) that does not change occurs.

WO 16/125374

The dead period between buck operation and boost operation is a factor that distorts the output current. There is a demand for seamless switching between the step-down operation and the step-up operation without generating such a dead period.

The present disclosure has been made in view of such circumstances, and its object is to provide a power conversion device capable of smoothly switching between step-down operation and step-up operation.

In order to solve the above problems, a power converter according to an aspect of the present disclosure includes a first leg in which a first switching element and a second switching element are connected in series, and a third switching element and a fourth switching element in series. a first bridge circuit in which the first leg and the second leg are connected in parallel to the first DC section; and a third bridge circuit in which a fifth switching element and a sixth switching element are connected in series. a second bridge circuit having a leg, a fourth leg in which a seventh switching element and an eighth switching element are connected in series, and in which the third leg and the fourth leg are connected in parallel to a second DC section; An isolation transformer connected between the first bridge circuit and the second bridge circuit, and a control circuit for controlling the first switching element to the eighth switching element. A diode is connected or formed in inverse parallel to each of the first switching element to the eighth switching element, and the control circuit is configured such that the first bridge circuit a transmission state in which the second bridge circuit conducts the secondary winding of the isolating transformer with the second DC section, short-circuiting both ends of the primary winding in the first bridge circuit; a first mode of operation in which a second bridge circuit is controlled to include a commutation state in which the secondary winding is in communication with the second DC section; a storage state in which the winding is conductive and both ends of the secondary winding are short-circuited in the second bridge circuit; a second operation mode for controlling to include the transmission state; the transmission state and the storage; and a third operating mode controlling to include the commutation state.

According to the present disclosure, it is possible to smoothly switch between the step-down operation and the step-up operation.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure for demonstrating the structure of the power converter device which concerns on embodiment. FIGS. 2(a) to 2(c) are diagrams for explaining the operating state of the power conversion device according to Comparative Example 1. FIG. FIGS. 3(a) to 3(c) are diagrams for explaining the operating state of the power converter according to Comparative Example 2. FIG. FIGS. 4A to 4D are diagrams for explaining switching patterns of the first switching element to the eighth switching element according to Comparative Example 2 of the power converter. FIGS. 5(a) to 5(d) are diagrams for explaining operating states according to the embodiment of the power converter. FIGS. 6A to 6C are diagrams for explaining switching patterns of the first switching element to the eighth switching element according to the embodiment of the power converter. FIG. 4 is a diagram for explaining switching among a first operation mode, a second operation mode, and a third operation mode according to the embodiment; FIGS. 8A to 8C are diagrams for explaining switching patterns during reverse transmission of the first switching element to the eighth switching element according to the embodiment of the power converter. FIGS. 9A to 9C are diagrams for explaining switching patterns of the first switching element to the eighth switching element according to the modification of the power converter.

FIG. 1 is a diagram for explaining the configuration of the power converter 1 according to the embodiment. The power conversion device 1 is an insulated bidirectional DC/DC converter (DAB converter), converts DC power supplied from a first DC power supply E1, and transmits the converted DC power to a second DC power supply E2. The power conversion device 1 also converts the DC power supplied from the second DC power supply E2 and transmits the converted DC power to the first DC power supply E1. The power converter 1 can step down the voltage for power transmission, or step up the voltage for power transmission.

The first DC power source E1 corresponds to, for example, a storage battery or electric double layer capacitor mounted on an EV, or a stationary storage battery or electric double layer capacitor. The second DC power supply E2 corresponds to, for example, a DC bus connected to a commercial power system via an inverter. Other storage batteries, solar cells, fuel cells, or the like may be connected to the DC bus via other DC/DC converters.

The power converter 1 includes a primary capacitor Ca, a first bridge circuit 11, a first inductor L1, an isolation transformer TR1, a second inductor L2, a second bridge circuit 12, a secondary capacitor Cb, and a control circuit 13.

A primary side capacitor Ca is connected in parallel with the first DC power supply E1. A secondary capacitor Cb is connected in parallel with the second DC power supply E2. For example, electrolytic capacitors are used for the primary side capacitor Ca and the secondary side capacitor Cb. In this specification, the first DC power source E1 and the primary side capacitor Ca are collectively called a first DC section, and the second DC power source E2 and the secondary side capacitor Cb are collectively called a second DC section.

In the first bridge circuit 11, a first leg in which a first switching element Q1 and a second switching element Q2 are connected in series and a second leg in which a third switching element Q3 and a fourth switching element Q4 are connected in series are connected in parallel. This is a full bridge circuit configured by The first bridge circuit 11 is connected in parallel with the first DC section, and the middle point of the first leg and the middle point of the second leg are connected to both ends of the primary winding n1 of the isolation transformer TR1. The first bridge circuit 11 can convert the DC voltage on the primary side supplied from the first DC section into AC voltage and output it to the primary winding n1 of the isolation transformer TR1. The first bridge circuit 11 can also convert the AC voltage supplied from the primary winding n1 of the isolation transformer TR1 into a DC voltage and output it to the first DC section.

In the second bridge circuit 12, a third leg in which a fifth switching element Q5 and a sixth switching element Q6 are connected in series and a fourth leg in which a seventh switching element Q7 and an eighth switching element Q8 are connected in series are connected in parallel. This is a full bridge circuit configured by The second bridge circuit 12 is connected in parallel with the second DC section, and the middle point of the third leg and the middle point of the fourth leg are connected to both ends of the secondary winding n2 of the isolation transformer TR1. The second bridge circuit 12 can convert the secondary-side DC voltage supplied from the second DC section into an AC voltage and output it to the secondary winding n2 of the isolation transformer TR1. Also, the second bridge circuit 12 can convert the AC voltage supplied from the secondary winding n2 of the insulating transformer TR1 into a DC voltage and output it to the second DC section.

A first diode D1 to an eighth diode D8 are connected or formed in antiparallel to the first switching element Q1 to the eighth switching element Q8, respectively. A first capacitor C1 to an eighth capacitor C8 are connected or formed in parallel to the first switching element Q1 to the eighth switching element Q8, respectively.

For example, an IGBT (Insulated Gate Bipolar Transistor) or a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) can be used for the first switching element Q1 to the eighth switching element Q8. When an IGBT is used for the first switching element Q1-eighth switching element Q8, the first diode D1-eighth diode is connected between the collector and emitter of the first switching element Q1-eighth switching element Q8. Connect as D8 respectively. Alternatively, external capacitors may be connected between the collectors and emitters of the first switching element Q1 to the eighth switching element Q8 as first capacitance C1 to the eighth capacitance C8, respectively, or the first switching element Q1 to the eighth switching element Q8 may be connected. Parasitic capacitances respectively formed between the collector and emitter of are used as the first capacitance C1 to the eighth capacitance C8.

When MOSFETs are used for the first switching element Q1 to the eighth switching element Q8, the parasitic diodes formed between the drain and source of the first switching element Q1 to the eighth switching element Q8 are the first diode D1 to the eighth switching element Q8. Either the diode D8 is used, or external diode elements are connected as the first diode D1 to the eighth diode D8, respectively. Also, the parasitic capacitances formed between the drain and source of the first switching element Q1-eighth switching element Q8 are used as the first capacitance C1-eighth capacitance C8, or the first switching element Q1-eighth switching element External capacitors are connected between the drain and source of Q8 as first capacitor C1 to eighth capacitor C8, respectively.

The capacitance values of the first capacitor C1 to the eighth capacitor C8 connected or formed in parallel with the first switching element Q1 to the eighth switching element Q8 respectively correspond to each other. That is, the capacitance values between the collector and emitter or between the drain and source of the first switching element Q1 to the eighth switching element Q8 are substantially equal. Similarly, the resistance values of the first diode D1 to the eighth diode D8 connected or formed in antiparallel with the first switching element Q1 to the eighth switching element Q8, respectively, all correspond. In this way, the configurations of the first leg to the fourth leg all correspond to each other, which contributes to the reduction of manufacturing cost and circuit area. Also, any switching pattern can be flexibly adapted.

The isolation transformer TR1 is connected between the AC terminals of the first bridge circuit 11 and the AC terminals of the second bridge circuit 12 . The isolation transformer TR1 converts the output voltage of the first bridge circuit 11 connected to the primary winding n1 according to the turns ratio between the primary winding n1 and the secondary winding n2, and is connected to the secondary winding n2. output to the second bridge circuit 12. Also, the isolation transformer TR1 converts the output voltage of the second bridge circuit 12 connected to the secondary winding n2 according to the turns ratio between the secondary winding n2 and the primary winding n1, and connects it to the primary winding n1. output to the first bridge circuit 11 where the

The first inductance L1 is connected or formed in series between the AC terminal of the first bridge circuit 11 and the primary winding n1 of the isolation transformer TR1. A second inductance L2 is connected or formed in series between the AC terminal of the second bridge circuit 12 and the secondary winding n2 of the isolation transformer TR1. In the example shown in FIG. 1, the first inductance L1 is composed of a reactor element connected between the midpoint of the first leg of the first bridge circuit 11 and the primary winding n1 of the isolation transformer TR1. The second inductance L2 is composed of a reactor element connected between the middle point of the third leg of the second bridge circuit 12 and the secondary winding n2 of the isolation transformer TR1.

It should be noted that the first inductance L1 may be composed of the leakage inductance of the primary winding n1 formed between the midpoint of the first leg of the first bridge circuit 11 and the primary winding n1 of the isolation transformer TR1. . The second inductance L2 may be composed of the leakage inductance of the secondary winding n2 formed between the middle point of the third leg of the second bridge circuit 12 and the secondary winding n2 of the isolation transformer TR1. . Either one of the first inductance L1 and the second inductance L2 may be omitted.

Although not shown in FIG. 1, a first voltage sensor that detects the voltage across the first DC section, a first current sensor that detects the current flowing through the first DC section, and a second voltage sensor that detects the voltage across the second DC section. Two voltage sensors and a second current sensor that detects the current flowing through the second DC section are provided, and the respective detection values are output to the control circuit 13 .

The control circuit 13 supplies a driving signal (PWM (Pulse Width Modulation) signal) to the gate terminals or base terminals of the first switching element Q1 to the eighth switching element Q8, thereby controlling the first switching element Q1 to the eighth switching element Q8. Control Q8. The configuration of the control circuit 13 can be realized by cooperation of hardware resources and software resources, or only by hardware resources. Analog devices, microcontrollers, DSPs, ROMs, RAMs, ASICs, FPGAs, and other LSIs can be used as hardware resources. Programs such as firmware can be used as software resources.

The control circuit 13 executes the following control as basic control. When power is transmitted from the first DC section to the second DC section (when discharging from the first DC power source E1), the control circuit 13 detects the current value (discharge current value) detected by the first current sensor as the current command value. or so that the voltage value (discharge voltage value) detected by the first voltage sensor maintains the voltage command value. Note that the secondary-side current value detected by the second current sensor may be controlled, and the secondary-side voltage value detected by the second voltage sensor may be controlled.

Further, when power is transmitted from the second DC section to the first DC section (when charging the first DC power supply E1), the control circuit 13 determines that the current value (charging current value) detected by the first current sensor is the current command. The first switching element Q1 to the eighth switching element Q8 are controlled so as to maintain the value or so that the voltage value (charge voltage value) detected by the first voltage sensor maintains the voltage command value. Note that the secondary-side current value detected by the second current sensor may be controlled, and the secondary-side voltage value detected by the second voltage sensor may be controlled.

In this way, the DAB converter has a symmetrical configuration on the primary side and the secondary side, and can transmit power in both directions. The operation of the power converter 1 will be described below.

(Comparative example 1)
FIGS. 2A to 2C are diagrams for explaining the operating state of the power converter 1 according to Comparative Example 1. FIG. In the first state shown in FIG. 2A, the control circuit 13 turns on the first switching element Q1, the fourth switching element Q4, the sixth switching element Q6, and the seventh switching element Q7, the second switching element Q2, The third switching element Q3, the fifth switching element Q5 and the eighth switching element Q8 are controlled to be turned off. In this state, power is charged from the first DC power supply E1 to the first inductor L1, and power is charged from the second DC power supply E2 to the second inductor L2.

In the second state shown in FIG. 2B, the control circuit 13 turns on the first switching element Q1, the fourth switching element Q4, the fifth switching element Q5, and the eighth switching element Q8, the second switching element Q2, The third switching element Q3, the sixth switching element Q6 and the seventh switching element Q7 are controlled to be turned off. In this state, the power of the first DC power supply E1, the power accumulated in the first inductor L1, and the power accumulated in the second inductor L2 are transmitted to the second DC power supply E2.

In a third state (not shown), the control circuit 13 turns on the second switching element Q2, the third switching element Q3, the fifth switching element Q5, and the eighth switching element Q8, and turns on the first switching element Q1 and the fourth switching element Q1. The element Q4, the sixth switching element Q6 and the seventh switching element Q7 are controlled to be turned off. In this state, power is charged from the first DC power supply E1 to the first inductor L1, and power is charged from the second DC power supply E2 to the second inductor L2.

In a fourth state (not shown), the control circuit 13 turns on the second switching element Q2, the third switching element Q3, the sixth switching element Q6, and the seventh switching element Q7, and turns on the first switching element Q1 and the fourth switching element Q1. The element Q4, the fifth switching element Q5 and the eighth switching element Q8 are controlled to be turned off. In this state, the power of the first DC power supply E1, the power accumulated in the first inductor L1, and the power accumulated in the second inductor L2 are transmitted to the second DC power supply E2.

In the control according to Comparative Example 1, the power of the second DC power supply E2 is charged to the second inductor L2 in the first state (see FIG. 2(a)) and the third state (not shown). In the subsequent second state (see FIG. 2(b)) and fourth state (not shown), the power accumulated in the second inductor L2 is discharged to the second DC power source E2. That is, a reactive current irrelevant to power transmission flows on the secondary side. Wasteful loss occurs due to the flow of this reactive current.

FIG. 2(c) shows the flow of current when the voltage of the first DC power supply E1 is significantly lower than the voltage of the second DC power supply E2 in the second state shown in FIG. 2(b). . When the voltage of the second DC power supply E2 becomes higher than the voltage of the first DC power supply E1, the direction of current is reversed, and the current flows back from the second DC power supply E2 to the first DC power supply E1. In this state, when the first switching element Q1 and the fourth switching element Q4 are turned off and the second switching element Q2 and the third switching element Q3 are turned on in order to transition to the next state, the second switching element Q2 and the third switching element Q3 are turned on. The third switching element Q3 goes into hard switching, and the first diode D1 of the first switching element Q1 and the fourth diode D4 of the fourth switching element Q4 go into recovery operation, increasing the loss.

(Comparative example 2)
FIGS. 3A to 3C are diagrams for explaining the operating state of the power converter 1 according to Comparative Example 2. FIG. FIGS. 4A to 4D are diagrams for explaining switching patterns of the first switching element Q1 to the eighth switching element Q8 according to Comparative Example 2 of the power converter 1. FIG. Comparative Example 2 employs a phase shift method. The duty ratio of the first switching element Q1 to the sixth switching element Q6 is fixed at 50%, and the seventh switching element Q7 and the eighth switching element Q8 are kept in the fully off state.

As shown in FIGS. 4A and 4B, in the step-down operation of Comparative Example 2, the phase of the first leg (first switching element Q1 and second switching element Q2) is fixed, and the phase of the second leg (third switching element Q2) is fixed. By making the phase of Q3 and the fourth switching element Q4) variable and controlling the phase of the second leg, the phase difference θ1 between the first leg and the second leg is controlled. The third leg (the fifth switching element Q5 and the sixth switching element Q6) is controlled in synchronization with the second leg. When increasing the power transmitted from the primary side to the secondary side, the control circuit 13 controls the phase difference θ1 to decrease (shifts the phase of the second leg to the left), and transmits from the primary side to the secondary side. When decreasing the power to be applied, control is performed so that the phase difference θ1 increases (the phase of the second leg is shifted to the right).

As shown in FIGS. 4(c)-(d), in the boosting operation of Comparative Example 2, the phases of the first leg and the second leg are fixed, the phase of the third leg is variable, and the phase of the third leg is controlled. By doing so, the phase difference θ2 between the first and second legs and the third leg is controlled. When increasing the power transmitted from the primary side to the secondary side, the control circuit 13 controls the phase difference θ2 to increase (shifts the phase of the third leg to the right), and transmits from the primary side to the secondary side. When decreasing the power to be supplied, control is performed so that the phase difference θ2 becomes smaller (the phase of the third leg is shifted to the left).

FIG. 3(a) shows a state in which power is transmitted from the first DC power source E1 to the second DC power source E2 (hereinafter referred to as a transmission state). In the transmission state, the second bridge circuit 12 on the secondary side only needs to be in the rectifying state, and both the fifth switching element Q5 and the sixth switching element Q6 constituting the third leg may be controlled to be in the OFF state. .

FIG. 3(b) shows a state in which power is transmitted from the first inductor L1 and the second inductor L2 to the second DC power supply E2 (hereinafter referred to as a commutation state). FIG. 3(c) shows a state in which electric power is accumulated in the first inductor L1 and the second inductor L2 from the first DC power source E1 (hereinafter referred to as an accumulation state).

In step-down operation, the voltage or current of the power to be transmitted is controlled by the ratio between the transmission state and the commutation state. The higher the ratio of commutation states, the lower the voltage or current of the power to be transmitted is controlled. In step-up operation, the voltage or current of the power to be transmitted is controlled by the ratio between the transmission state and the storage state. The higher the stored state ratio, the higher the voltage or current of the power to be transmitted is controlled.

In Comparative Example 2, since the seventh switching element Q7 and the eighth switching element Q8 are kept completely off, current flows backward from the second DC power supply E2 to the second inductor L2, the first inductor L1, and the first DC power supply E1. never do. That is, there is no reactive current due to reverse current flow from the second DC power supply E2 as shown in the first comparative example. Further, even if the voltage of the second DC power supply E2 becomes higher than the voltage of the first DC power supply E1, current does not flow back from the second DC power supply E2 to the first DC power supply E1. Therefore, recovery loss by the first diode D1 and the fourth diode D4 and hard switching of the second switching element Q2 and the third switching element Q3 can be suppressed.

However, it is necessary to insert dead time Td of the third leg when transitioning from the switching pattern at maximum power for step-down operation shown in FIG. 4(b) to the switch pattern at minimum power for boost operation shown in FIG. 4(c). There is That is, in order to make a transition from a step-down operation to a step-up operation, it is necessary to make a transition from a transmission state to an accumulation state, and it is necessary to insert a dead time Td during this transition. The dead time Td is a period (dead period) during which the transmitted power does not change with respect to changes in the control operation amount (changes in the switching waveform). That is, although the control circuit 13 controls to increase the power to be transmitted, it is a period in which the power does not actually increase. This dead period tends to cause distortion in the output current. In the following, this embodiment proposes a DAB converter control method that does not generate a reverse current from the second DC power supply E2 and does not generate a dead period. Note that the dead period also occurs in the PWM method.

(Example)
FIGS. 5(a) to 5(d) are diagrams for explaining operating states according to the embodiment of the power conversion device 1. FIG. 6A to 6C are diagrams for explaining switching patterns of the first switching element Q1 to the eighth switching element Q8 according to the embodiment of the power converter 1. FIG. This embodiment employs the PWM method, and the control circuit 13 controls the ON/OFF time of each switching element Q1 to the eighth switching element Q8, so that the first DC section changes to the second switching element. Controls the voltage or current of the power transmitted to the DC section.

Also in this embodiment, the voltage or current of the power to be transmitted is controlled by switching the transmission state, commutation state, and accumulation state. In the transmission state, the first bridge circuit 11 conducts the first DC section and the primary winding n1 of the isolation transformer TR1, and the second bridge circuit 12 conducts the secondary winding n2 of the isolation transformer TR1 to the second DC section. state.

The transmission state includes the first pattern and the second pattern. The first pattern is a pattern in which the first switching element Q1 and the fourth switching element Q4 are in an ON state, the second switching element Q2 and the third switching element Q3 are in an OFF state, and the second bridge circuit 12 is in a rectifying state. (See FIGS. 5(a)-(b)). The transmission state a shown in FIG. 5A is an example of diode rectification on the secondary side, and the transmission state b shown in FIG. 5B is an example of synchronous rectification on the secondary side. The second pattern is a pattern in which the second switching element Q2 and the third switching element Q3 are on, the first switching element Q1 and the fourth switching element Q4 are off, and the second bridge circuit 12 is in the rectifying state. .

In the commutation state, both ends of the primary winding n1 of the isolation transformer TR1 are short-circuited within the first bridge circuit 12, and the second bridge circuit 12 electrically connects the secondary winding n2 of the isolation transformer TR1 to the second DC section. state. The commutation state includes a third pattern and a fourth pattern. In the third pattern, the first switching element Q1 or the fourth switching element Q4 is in the ON state, the fourth switching element Q4 or the first switching element Q1, and the second switching element Q2 and the third switching element Q3 are in the OFF state, This is a pattern in which the second bridge circuit 12 is in a rectifying state (see FIG. 5(c)). In the fourth pattern, the second switching element Q2 or the third switching element Q3 is in the ON state, the third switching element Q3 or the second switching element Q2, and the first switching element Q1 and the fourth switching element Q4 are in the OFF state, This is a pattern in which the second bridge circuit 12 is in a rectifying state.

In the accumulation state, the first bridge circuit 11 conducts the first DC part and the primary winding n1 of the isolation transformer TR1, and both ends of the secondary winding n2 of the isolation transformer TR1 are short-circuited in the second bridge circuit 12. be. The accumulation state includes a fifth pattern and a sixth pattern. A fifth pattern is a pattern in which the first switching element Q1, the fourth switching element Q4, and the sixth switching element Q6 or the seventh switching element Q7 are in the ON state, and the remaining switching elements are in the OFF state. A sixth pattern is a pattern in which the second switching element Q2, the third switching element Q3, and the fifth switching element Q5 or the eighth switching element Q8 are in the ON state, and the remaining switching elements are in the OFF state.

The control circuit 13 synchronizes the period of the first pattern and the period of the second pattern. That is, the period of the first pattern and the period of the second pattern are controlled to be substantially the same. Further, the control circuit 13 synchronizes the period of the third pattern and the period of the fourth pattern. That is, the period of the third pattern and the period of the fourth pattern are controlled to be substantially the same time. Further, the control circuit 13 synchronizes the period of the fifth pattern and the period of the sixth pattern. That is, the period of the fifth pattern and the period of the sixth pattern are controlled to be substantially the same time. By these controls, positive and negative symmetrical operation can be achieved, and the occurrence of DC bias magnetism in the insulating transformer TR1 can be suppressed.

FIG. 6(a) shows the switching pattern in the first operation mode. The first operation mode is an operation mode during step-down. In the first operation mode, the duty ratio of one of the first leg and the second leg is fixed at 100% (duty ratio=1), and the duty ratio of the other leg is variable. In this embodiment, duty ratio=100% (duty ratio=1) is defined as (half cycle (Tsw/2)−dead time Td). In the example shown in FIG. 6A, the duty ratio of the second leg is fixed at 100% and the duty ratio of the first leg is variable. The higher the duty ratio of the first leg (the longer the ON time), the longer the transmission period than the commutation period, and the more power is transmitted. Thus, in step-down operation, the voltage or current of power to be transmitted is controlled by PWM control on the primary side.

In the first operation mode, the control circuit 13 turns on the fourth switching element Q4 in synchronization with turning on the first switching element Q1. Next, the control circuit 13 turns on the eighth switching element Q8 in synchronization with the turning off of the first switching element Q1. When the duty ratio of the second leg is variable, the fourth switching element Q4 is turned off instead of the first switching element Q1.

Synchronous rectification is performed by turning on the eighth switching element Q8. Since synchronous rectification has less loss than diode rectification, loss on the secondary side is reduced compared to the case where current passes through the eighth diode D8 while the eighth switching element Q8 is in the OFF state. In addition, when the fifth switching element Q5 is in the OFF state, current passes through the fifth diode D5, thereby preventing the direction of the current flowing to the secondary side from reversing. Note that the fifth switching element Q5 may be turned on instead of the eighth switching element Q8. If synchronous rectification is not used, it is not necessary to turn on the eighth switching element Q8 and the fifth switching element Q5.

Next, the control circuit 13 turns off the eighth switching element Q8 in synchronization with turning off the fourth switching element Q4.

With the dead time Td in between, the control circuit 13 turns on the third switching element Q3 in synchronization with the turn-on of the second switching element Q2. Next, the control circuit 13 turns on the seventh switching element Q7 in synchronization with turning off the second switching element Q2. When the duty ratio of the second leg is made variable, the third switching element Q3 is turned off instead of the second switching element Q2.

Synchronous rectification is performed by turning on the seventh switching element Q7. The sixth switching element Q6 may be turned on instead of the seventh switching element Q7. If synchronous rectification is not used, it is not necessary to turn on the seventh switching element Q7 and the sixth switching element Q6.

Next, the control circuit 13 turns off the seventh switching element Q7 in synchronization with turning off the third switching element Q3. One cycle is completed by the above.

FIG. 6(b) shows the switching pattern of the second operation mode. The second operation mode is an operation mode during boosting. In the second operation mode, the duty ratios of both the first leg and the second leg are fixed at 100%, the duty ratio of one of the third leg and the fourth leg is variable, and the other leg Complementary operation with leg or all off state. In the example shown in FIG. 6B, the power transmitted is controlled by the duty ratio of the third leg. longer, increasing the power transmitted. In this way, in the step-up operation, the voltage or current of the power to be transmitted is controlled by PWM control on the secondary side.

In the second operation mode, the control circuit 13 turns on the fourth switching element Q4 and the sixth switching element Q6 in synchronization with turning on the first switching element Q1. Note that the seventh switching element Q7 may be turned on instead of the sixth switching element Q6.

Next, the control circuit 13 turns on the eighth switching element Q8 in synchronization with turning off the sixth switching element Q6. When the seventh switching element Q7 is turned off instead of the sixth switching element Q6, the fifth switching element Q5 is turned on instead of the eighth switching element Q8. If synchronous rectification is not used, it is not necessary to turn on the eighth switching element Q8 and the fifth switching element Q5.

Next, the control circuit 13 turns off the fourth switching element Q4 and the eighth switching element Q8 in synchronization with the turning off of the first switching element Q1. After the dead time Td, the control circuit 13 turns on the third switching element Q3 and the fifth switching element Q5 in synchronization with the turning on of the second switching element Q2. The eighth switching element Q8 may be turned on instead of the fifth switching element Q5.

Next, the control circuit 13 turns on the seventh switching element Q7 in synchronization with turning off the fifth switching element Q5. When the eighth switching element Q8 is turned off instead of the fifth switching element Q5, the sixth switching element Q6 is turned on instead of the seventh switching element Q7. If synchronous rectification is not used, it is not necessary to turn on the seventh switching element Q7 and the sixth switching element Q6.

Next, the control circuit 13 turns off the third switching element Q3 and the seventh switching element Q7 in synchronization with turning off the second switching element Q2. One cycle is completed by the above.

FIG. 6(c) shows the switching pattern of the third operation mode. A third operation mode is an operation mode when the step-down operation is switched to the step-up operation. The third operation mode is activated when the duty ratio of the first leg reaches a threshold α obtained by subtracting the duty ratio corresponding to the dead time from 100% in the step-down operation mode. The threshold α can be appropriately set to any value. In the third operation mode, power control by PWM control on the primary side in the first operation mode and power control by PWM control on the secondary side in the second operation mode coexist.

In the third operation mode, the control circuit 13 turns on the fourth switching element Q4 and the sixth switching element Q6 in synchronization with turning on the first switching element Q1. Note that the seventh switching element Q7 may be turned on instead of the sixth switching element Q6.

Next, the control circuit 13 turns off the first switching element Q1. When the duty ratio of the second leg is variable, the fourth switching element Q4 is turned off instead of the first switching element Q1.

Next, the control circuit 13 turns off the eighth switching element Q8 in synchronization with turning off the fourth switching element Q4. When the duty ratio of the second leg is variable, the first switching element Q1 is turned off instead of the fourth switching element Q4.

With the dead time Td in between, the control circuit 13 turns on the third switching element Q3 and the fifth switching element Q5 in synchronization with the turning on of the second switching element Q2. The eighth switching element Q8 may be turned on instead of the fifth switching element Q5.

Next, the control circuit 13 turns off the second switching element Q2. When the duty ratio of the second leg is made variable, the third switching element Q3 is turned off instead of the second switching element Q2.

Next, the control circuit 13 turns off the seventh switching element Q7 in synchronization with turning off the third switching element Q3. When the duty ratio of the second leg is variable, the second switching element Q2 is turned off instead of the third switching element Q3. One cycle is completed by the above.

FIG. 7 is a diagram for explaining switching among the first operation mode, the second operation mode, and the third operation mode according to the embodiment. In this embodiment, a third operation mode is interposed between the first operation mode (step down) and the second operation mode (step up).

The control circuit 13 calculates the control operation amount based on the deviation between the target value of the voltage or current to be controlled and the actual detected value. For example, the deviation is PI-compensated to calculate the control operation amount. The control circuit 13 switches the operation mode based on the calculated control operation amount.

In the first operation mode, the control circuit 13 PWM-controls the first leg, fixes the second leg to a duty ratio of 100%, sets the third leg to a fully off state, and sets the fourth leg to a complementary state to the first leg. make it work. When synchronous rectification is not performed, the fourth leg is also turned off.

In the second operation mode, the control circuit 13 fixes the duty ratio of the first leg and the second leg to 100%, PWM-controls the third leg, and causes the fourth leg to operate complementary to the third leg. Note that when synchronous rectification is not to be performed, the fourth leg is completely off.

In the third operation mode, the control circuit 13 PWM-controls the first leg, fixes the duty ratio of the second leg to 100%, PWM-controls the third leg, and operates the fourth leg and the third leg in complementary operation. Let Note that when synchronous rectification is not to be performed, the fourth leg is completely off.

The control circuit 13 switches from the first operation mode to the third operation mode at the timing when the duty ratio of the first leg rises to the threshold α obtained by subtracting the duty ratio corresponding to the dead time from 100%. The control circuit 13 continues the PWM control of the first leg until the duty ratio of the third leg rises to the threshold value β obtained by adding the duty ratio corresponding to the dead time to 0%. The threshold β can be appropriately set to any value.

The control circuit 13 switches from the second operation mode to the third operation mode at the timing when the duty ratio of the third leg has decreased to the threshold value β. The control circuit 13 continues the PWM control of the third leg until the duty ratio of the first leg drops to the threshold value β.

Thus, in the first operation mode, the control circuit 13 controls the voltage or current of power transmitted from the first DC section to the second DC section by controlling the duty ratio of the first leg. Further, in the second operation mode, the control circuit 13 controls the voltage or current of power transmitted from the first DC section to the second DC section by controlling the duty ratio of the third leg. Further, in the third operation mode, the control circuit 13 controls the duty ratio of the first leg and the duty ratio of the third leg to control the voltage or current of the power transmitted from the first DC section to the second DC section. Control. The control circuit 13 makes the transition to the third operation mode before the duty ratio of the first leg reaches 1 in the first operation mode. In addition, the control circuit 13 makes the transition to the third operation mode before the duty ratio of the third leg reaches zero in the second operation mode.

FIGS. 8(a)-(c) are diagrams for explaining switching patterns during reverse transmission of the first switching element Q1 to the eighth switching element Q8 according to the embodiment of the power converter 1. FIG. In the switching patterns of the first switching element Q1 to the eighth switching element Q8 shown in FIGS. 6(a) to 6(c), an example of transmitting power from the first DC section to the second DC section has been described. In this regard, it is also possible to transmit power from the second DC section to the first DC section. In this case, as shown in FIGS. 8A to 8C, the control circuit 13 supplies the drive signal to the first switching element Q1 to the fourth switching element Q4, the fifth switching element Q5 to the eighth switching element It suffices to replace the drive signal supplied to Q8.

As described above, according to this embodiment, by providing the third operation mode, it is possible to smoothly switch between the step-down operation and the step-up operation. Unlike Comparative Example 2, a dead period does not occur between the step-down operation and the step-up operation, and distortion of the output current can be suppressed.

In addition, there is no period in which the current flows backward from the second DC power supply E2 to the second inductor L2, the first inductor L1, and the first DC power supply E1, and there is no reactive current due to the current flowing backward from the second DC power supply E2. does not occur. Further, even if the voltage of the second DC power supply E2 becomes higher than the voltage of the first DC power supply E1, current does not flow back from the second DC power supply E2 to the first DC power supply E1. Therefore, recovery loss by the first diode D1 and the fourth diode D4 and hard switching of the second switching element Q2 and the third switching element Q3 can be suppressed.

Also, according to this embodiment, since the control is performed by the PWM method instead of the phase shift method, it is possible to easily generate the dead time when all of the first switching element Q1 to the eighth switching element Q8 are off. As a result, it is possible to suppress the occurrence of diode recovery loss. As described above, according to this embodiment, it is possible to smoothly switch between the step-down operation and the step-up operation, and to achieve high efficiency.

The present disclosure has been described above based on the embodiment. It is to be understood by those skilled in the art that the embodiment is an example, and that various modifications are possible in the combination of each component and each treatment process, and such modifications are also within the scope of the present disclosure. .

In the above embodiment, an example was explained in which power is controlled by the PWM control method on both the primary side and the secondary side. In the following modified example, an example will be described in which power control is performed on the primary side by the phase shift method and on the secondary side by the PWM method.

9(a)-(c) are diagrams for explaining the switching patterns of the first switching element Q1 to the eighth switching element Q8 according to the modification of the power conversion device 1. FIG. FIG. 9(a) shows a switching pattern in the first operation mode according to the modification. The first operation mode is an operation mode during step-down. In a first mode of operation, the phase of one of the first and second legs is fixed and the phase of the other leg is shifted. In the example shown in FIG. 9A, the phase of the second leg is fixed and the phase of the first leg is shifted. The smaller the phase difference between the first leg and the second leg, the longer the transmission period than the commutation period, and the more power is transmitted. The commutation period shown in FIG. 9(a) includes two types of commutation period a, in which the second diode D2 conducts and diode rectification occurs, and commutation period b in which the second switching element Q2 performs synchronous rectification. be Thus, in step-down operation, phase shift control on the primary side controls the voltage or current of the power to be transmitted. The control on the secondary side is the same as the control in the above embodiment shown in FIG. 6(a).

FIG. 9(b) shows the switching pattern of the second operation mode. The second operation mode is an operation mode during boosting. The control at the time of boosting is the same as the control of the above embodiment shown in FIG. 6(a).

FIG. 9(c) shows the switching pattern of the third operation mode according to the modification. A third operation mode is an operation mode when the step-down operation is switched to the step-up operation. The third operating mode is activated when the phase difference between the first leg and the second leg in the first operating mode is reduced to the phase difference θ corresponding to the dead time. In the third operation mode, power control by phase shift control on the primary side in the first operation mode and power control by PWM control on the secondary side in the second operation mode coexist.

By thus performing phase shift control on the primary side and PWM control on the secondary side, it is also possible to realize the first operation mode to the third operation mode. By phase-shifting the primary side, there is no period in which the switching elements Q1-Q8 are completely off in the first and part of the third operation mode, but synchronous rectification is performed during the commutation state. It can be performed.

In the above embodiment, an example is assumed in which IGBTs or MOSFETs are used for the first switching element Q1 to the eighth switching element Q8. In this respect, the first switching element Q1 to the eighth switching element Q8 are made of wide bandgap semiconductors using silicon carbide (SiC), gallium nitride (GaN), gallium oxide (Ga2O3), diamond (C), etc. A switching element may be used.

The embodiment may be specified by the following items.

[Item 1]
It has a first leg in which a first switching element (Q1) and a second switching element (Q2) are connected in series, and a second leg in which a third switching element (Q3) and a fourth switching element (Q4) are connected in series. and a first bridge circuit (11) in which the first leg and the second leg are connected in parallel to a first DC section (E1, Ca);
It has a third leg in which a fifth switching element (Q5) and a sixth switching element (Q6) are connected in series, and a fourth leg in which a seventh switching element (Q7) and an eighth switching element (Q8) are connected in series. and a second bridge circuit (12) in which the third leg and the fourth leg are connected in parallel to a second DC section (E2, Cb);
an isolation transformer (TR1) connected between the first bridge circuit (11) and the second bridge circuit (12);
A control circuit (13) that controls the first switching element (Q1)-the eighth switching element (Q8),
Diodes (D1-D8) are connected or formed in antiparallel to each of the first switching element (Q1) to the eighth switching element (Q8),
The control circuit (13)
The first bridge circuit (11) connects the first DC section (E1, Ca) and the primary winding (n1) of the isolation transformer (TR1), and the second bridge circuit (12) connects the isolation transformer ( A transmission state in which the secondary winding (n2) of TR1) is electrically connected to the second DC part (E2, Cb), and both ends of the primary winding (n1) are short-circuited in the first bridge circuit (11). , a first operation mode in which the second bridge circuit (12) is controlled to include a commutation state in which the secondary winding (n2) is electrically connected to the second DC section (E2, Cb);
The first bridge circuit (11) electrically connects the first DC section (E1, Ca) and the primary winding (n1), and both ends of the secondary winding (n2) are connected to the second bridge circuit (12). a second mode of operation that controls to include an accumulation state shorted within and the transmission state;
a third operating mode that controls to include the transmission state, the accumulation state, and the commutation state;
A power converter (1) comprising:
According to this, it is possible to smoothly switch between the first operation mode and the second operation mode.
[Item 2]
the transmission state includes a first pattern and a second pattern, the commutation state includes a third pattern and a fourth pattern,
In the first pattern, the first switching element (Q1) and the fourth switching element (Q4) are in an ON state, and the second switching element (Q2) and the third switching element (Q3) are in an OFF state, the second bridge circuit (12) is in a rectifying state;
In the second pattern, the second switching element (Q2) and the third switching element (Q3) are in an ON state, and the first switching element (Q1) and the fourth switching element (Q4) are in an OFF state, the second bridge circuit (12) is in a rectifying state;
In the third pattern, the first switching element (Q1) or the fourth switching element (Q4) is in an ON state, and the fourth switching element (Q4) or the first switching element (Q1) and the second switching element (Q4) are switched on. the switching element (Q2) and the third switching element (Q3) are in an off state, and the second bridge circuit (12) is in a rectifying state;
In the fourth pattern, when the second switching element (Q2) or the third switching element (Q3) is in an ON state, the third switching element (Q3) or the second switching element (Q2) and the first The switching element (Q1) and the fourth switching element (Q4) are in an OFF state, and the second bridge circuit (12) is in a rectifying state.
A power converter (1) according to item 1.
According to this, the reactive current from the second DC section (E2, Cb) during the step-down operation can be suppressed, and the efficiency can be improved.
[Item 3]
the accumulation state includes a fifth pattern and a sixth pattern;
In the fifth pattern, the first switching element (Q1), the fourth switching element (Q4), and the sixth switching element (Q6) or the seventh switching element (Q7) are in an ON state, and the remaining switching elements are switched. the element is in the off state,
In the sixth pattern, the second switching element (Q2), the third switching element (Q3), and the fifth switching element (Q5) or the eighth switching element (Q8) are on, and the remaining switching elements are the element is in the off state,
3. A power converter (1) according to item 1 or 2.
According to this, it is possible to suppress the reactive current from the second DC section (E2, Cb) during the step-up operation, and it is possible to achieve high efficiency.
[Item 4]
The control circuit (13) controls the on/off time of each switching element to control the voltage or to control the current,
A power converter (1) according to any one of items 1 to 3.
According to this, by controlling by the PWM method without using the phase shift method, the dead time in the all-off state can be easily generated, and the recovery loss of the diode can be reduced.
[Item 5]
The control circuit (13)
By controlling the duty ratio of the first leg or the second leg in the first operation mode,
By controlling the duty ratio of the third leg or the fourth leg in the second operation mode,
By controlling the duty ratio of the first leg or the second leg and the duty ratio of the third leg or the fourth leg in the third operation mode,
Controlling the voltage or current of power transmitted from the first DC section (E1, Ca) to the second DC section (E2, Cb);
5. A power converter (1) according to item 4.
According to this, in the third operation mode, the PWM control in the first operation mode and the PWM control in the second operation mode coexist, thereby switching between the first operation mode and the second operation mode. You can switch smoothly.
[Item 6]
The control circuit (13)
In the first operation mode, transition to the third operation mode before the duty ratio of the first leg or the second leg reaches 1;
6. A power converter (1) according to item 5.
According to this, it is possible to smoothly switch from the first operation mode to the second operation mode.
[Item 7]
The control circuit (13)
In the second operation mode, transition to the third operation mode before the duty ratio of the third leg or the fourth leg reaches 0;
7. A power converter (1) according to item 5 or 6.
According to this, it is possible to smoothly switch from the second operation mode to the first operation mode.
[Item 8]
The control circuit (13)
In the first operating mode,
turning on the fourth switching element (Q4) in synchronization with turning on the first switching element (Q1);
turning on the eighth switching element (Q8) or the fifth switching element (Q5) in synchronization with turning off the first switching element (Q1) or the fourth switching element (Q4);
turning off the eighth switching element (Q8) or the fifth switching element (Q5) in synchronization with turning off the fourth switching element (Q4) or the first switching element (Q1);
turning on the third switching element (Q3) in synchronization with turning on the second switching element (Q2);
turning on the seventh switching element (Q7) or the sixth switching element (Q6) in synchronization with turning off the second switching element (Q2) or the third switching element (Q3);
Turning off the seventh switching element (Q7) or the sixth switching element (Q6) in synchronization with turning off the third switching element (Q3) or the second switching element (Q2);
8. A power converter (1) according to any one of items 1 to 7.
According to this, by controlling the step-down operation by the PWM method without using the phase shift method, the dead time in the all-off state can be easily generated, and the recovery loss of the diode can be reduced.
[Item 9]
The control circuit (13)
In the second operation mode,
turning on the fourth switching element (Q4) and the sixth switching element (Q6) or the seventh switching element (Q7) in synchronization with turning on the first switching element (Q1);
turning on the eighth switching element (Q8) or the fifth switching element (Q5) in synchronization with turning off the sixth switching element (Q6) or the seventh switching element (Q7);
turning off the fourth switching element (Q4) and the eighth switching element (Q8) or the fifth switching element (Q5) in synchronization with the turn-off of the first switching element (Q1);
turning on the third switching element (Q3) and the fifth switching element (Q5) or the eighth switching element (Q8) in synchronization with turning on the second switching element (Q2);
turning on the seventh switching element (Q7) or the sixth switching element (Q6) in synchronization with turning off the fifth switching element (Q5) or the eighth switching element (Q8);
Turning off the third switching element (Q3) and the seventh switching element (Q7) or the sixth switching element (Q6) in synchronization with turning off the second switching element (Q2);
A power converter (1) according to any one of items 1 to 8.
According to this, in the step-up operation, by controlling with the PWM method without using the phase shift method, the dead time in the all-off state can be easily generated, and the recovery loss of the diode can be reduced.
[Item 10]
The control circuit (13)
In the third operating mode,
turning on the fourth switching element (Q4) and the sixth switching element (Q6) or the seventh switching element (Q7) in synchronization with turning on the first switching element (Q1);
turning on the eighth switching element (Q8) or the fifth switching element (Q5) in synchronization with turning off the sixth switching element (Q6) or the seventh switching element (Q7);
turning off the first switching element (Q1) or the fourth switching element (Q4);
turning off the eighth switching element (Q8) or the fifth switching element (Q5) in synchronization with turning off the fourth switching element (Q4) or the first switching element (Q1);
turning on the third switching element (Q3) and the fifth switching element (Q5) or the eighth switching element (Q8) in synchronization with turning on the second switching element (Q2);
turning on the seventh switching element (Q7) or the sixth switching element (Q6) in synchronization with turning off the fifth switching element (Q5) or the eighth switching element (Q8);
turning off the second switching element (Q2) or the third switching element (Q3);
Turning off the seventh switching element (Q7) or the sixth switching element (Q6) in synchronization with turning off the third switching element (Q3) or the second switching element (Q2);
A power converter (1) according to any one of items 1 to 9.
According to this, when switching between the step-down operation and the step-up operation, by controlling with the PWM method without using the phase shift method, the dead time in the all-off state can be easily generated, and the recovery loss of the diode can be reduced. can be reduced.
[Item 11]
The control circuit (13)
synchronizing the period of the first pattern and the period of the second pattern;
synchronizing the period of the third pattern and the period of the fourth pattern;
3. A power converter (1) according to item 2.
According to this, the positive/negative symmetrical operation can be achieved, and the occurrence of DC bias magnetism can be suppressed.
[Item 12]
The control circuit (13)
synchronizing the period of the fifth pattern and the period of the sixth pattern;
4. A power converter (1) according to item 3.
According to this, the positive/negative symmetrical operation can be achieved, and the occurrence of DC bias magnetism can be suppressed.
[Item 13]
The control circuit (13)
When transmitting power from the secondary side to the primary side,
exchanging the drive signal supplied to the first switching element (Q1)-the fourth switching element (Q4) and the drive signal supplied to the fifth switching element (Q5)-the eighth switching element (Q8);
13. A power converter (1) according to any one of items 1 to 12.
Thereby, a DC/DC converter capable of bidirectional transmission can be realized.

The present invention can be used for power conditioners in photovoltaic power generation systems.

E1 First DC power supply, E2 Second DC power supply, 1 Power converter, 11 First bridge circuit, 12 Second bridge circuit, 13 Control circuit, Q1-Q8 Switching element, D1-D8 Diode, C1-C8 Capacitance, L1 First inductance, L2 second inductance, TR1 isolation transformer, n1 primary winding, n2 secondary winding, Ca primary side capacitor, Cb secondary side capacitor.

Claims

A first leg in which a first switching element and a second switching element are connected in series, and a second leg in which a third switching element and a fourth switching element are connected in series, wherein the first leg and the second leg are connected in series. a first bridge circuit connected in parallel to the first DC section;
A third leg in which a fifth switching element and a sixth switching element are connected in series, and a fourth leg in which a seventh switching element and an eighth switching element are connected in series, wherein the third leg and the fourth leg are connected in series. a second bridge circuit connected in parallel to the second DC section;
an isolation transformer connected between the first bridge circuit and the second bridge circuit;
A control circuit that controls the first switching element-the eighth switching element,
A diode is connected or formed in anti-parallel to each of the first switching element and the eighth switching element,
The control circuit is
a transmission state in which the first bridge circuit conducts the first DC section and the primary winding of the isolation transformer, and the second bridge circuit conducts the secondary winding of the isolation transformer with the second DC section; a first bridge circuit for controlling both ends of the primary winding to include a commutation state in which both ends of the primary winding are short-circuited in the first bridge circuit and the second bridge circuit conducts the secondary winding with the second DC section; mode of operation;
The first bridge circuit conducts the first direct current part and the primary winding, and controls to include the storage state in which both ends of the secondary winding are short-circuited in the second bridge circuit, and the transmission state. a second mode of operation to
a third operating mode that controls to include the transmission state, the accumulation state, and the commutation state;
A power conversion device having
the transmission state includes a first pattern and a second pattern, the commutation state includes a third pattern and a fourth pattern,
In the first pattern, the first switching element and the fourth switching element are in an ON state, the second switching element and the third switching element are in an OFF state, and the second bridge circuit is in a rectifying state,
In the second pattern, the second switching element and the third switching element are in an ON state, the first switching element and the fourth switching element are in an OFF state, and the second bridge circuit is in a rectifying state,
In the third pattern, the first switching element or the fourth switching element is in an ON state, and the fourth switching element or the first switching element, the second switching element and the third switching element are in an OFF state. , wherein the second bridge circuit is in a rectifying state;
In the fourth pattern, the second switching element or the third switching element is in an ON state, and the third switching element or the second switching element and the first switching element and the fourth switching element are in an OFF state. , wherein the second bridge circuit is in a rectifying state;
The power converter according to claim 1.
the accumulation state includes a fifth pattern and a sixth pattern;
In the fifth pattern, the first switching element, the fourth switching element, and the sixth switching element or the seventh switching element are in an ON state, and the remaining switching elements are in an OFF state;
In the sixth pattern, the second switching element, the third switching element, and the fifth switching element or the eighth switching element are in an ON state, and the remaining switching elements are in an OFF state.
The power converter according to claim 1 or 2.
The control circuit controls the voltage or current of power transmitted from the first DC section to the second DC section by controlling the on/off time of each switching element.
The power converter according to any one of claims 1 to 3.
The control circuit is
By controlling the duty ratio of the first leg or the second leg in the first operation mode,
By controlling the duty ratio of the third leg or the fourth leg in the second operation mode,
By controlling the duty ratio of the first leg or the second leg and the duty ratio of the third leg or the fourth leg in the third operation mode,
controlling the voltage or current of power transmitted from the first DC section to the second DC section;
The power converter according to claim 4.
The control circuit is
In the first operation mode, transition to the third operation mode before the duty ratio of the first leg or the second leg reaches 1;
The power converter according to claim 5.
The control circuit is
In the second operation mode, transition to the third operation mode before the duty ratio of the third leg or the fourth leg reaches 0;
The power converter according to claim 5 or 6.
The control circuit is
In the first operating mode,
turning on the fourth switching element in synchronization with turning on the first switching element;
turning on the eighth switching element or the fifth switching element in synchronization with turning off the first switching element or the fourth switching element;
turning off the eighth switching element or the fifth switching element in synchronization with turning off the fourth switching element or the first switching element;
turning on the third switching element in synchronization with turning on the second switching element;
turning on the seventh switching element or the sixth switching element in synchronization with turning off the second switching element or the third switching element;
turning off the seventh switching element or the sixth switching element in synchronization with turning off the third switching element or the second switching element;
The power converter according to any one of claims 1 to 7.
The control circuit is
In the second operation mode,
turning on the fourth switching element and the sixth switching element or the seventh switching element in synchronization with turning on the first switching element;
turning on the eighth switching element or the fifth switching element in synchronization with turning off the sixth switching element or the seventh switching element;
turning off the fourth switching element and the eighth switching element or the fifth switching element in synchronization with turning off the first switching element;
turning on the third switching element and the fifth switching element or the eighth switching element in synchronization with turning on the second switching element;
turning on the seventh switching element or the sixth switching element in synchronization with turning off the fifth switching element or the eighth switching element;
turning off the third switching element and the seventh switching element or the sixth switching element in synchronization with turning off the second switching element;
The power converter according to any one of claims 1 to 8.
The control circuit is
In the third operating mode,
turning on the fourth switching element and the sixth switching element or the seventh switching element in synchronization with turning on the first switching element;
turning on the eighth switching element or the fifth switching element in synchronization with turning off the sixth switching element or the seventh switching element;
turning off the first switching element or the fourth switching element;
turning off the eighth switching element or the fifth switching element in synchronization with turning off the fourth switching element or the first switching element;
turning on the third switching element and the fifth switching element or the eighth switching element in synchronization with turning on the second switching element;
turning on the seventh switching element or the sixth switching element in synchronization with turning off the fifth switching element or the eighth switching element;
turning off the second switching element or the third switching element;
turning off the seventh switching element or the sixth switching element in synchronization with turning off the third switching element or the second switching element;
The power converter according to any one of claims 1 to 9.
The control circuit is
synchronizing the period of the first pattern and the period of the second pattern;
synchronizing the period of the third pattern and the period of the fourth pattern;
The power converter according to claim 2.
The control circuit is
synchronizing the period of the fifth pattern and the period of the sixth pattern;
The power converter according to claim 3.
The control circuit is
When transmitting power from the secondary side to the primary side,
exchanging the drive signal supplied to the first switching element-the fourth switching element and the drive signal supplied to the fifth switching element-the eighth switching element;
The power converter according to any one of claims 1 to 12.