Switching loss optimization control method and system of energy storage DC converter

Abstract

The invention discloses a switching loss optimization control method and system of an energy storage DC converter. Comprising the following steps: firstly, acquiring battery side voltage / current and bus side voltage / current of the energy storage direct current converter; calculating according to the battery side voltage and the bus side voltage to obtain the voltage ratio of the two sides of the energy storage direct current converter; then, control power is obtained through calculation according to the battery side voltage / current and the bus side voltage / current; then, determining the working mode of the dual-active bridge circuit by using the control power of the energy storage direct-current converter; and finally, according to the working mode of the dual-active bridge circuit, the actual power of the dual-active bridge circuit is adjusted, and the switching loss optimization of the energy storage DC converter is completed. When the battery side voltage, the bus side voltage and the load power of the circuit are changed, the control power of the controller can be continuously changed, smooth transition is realized among all working modes, the output signal and the power gain are basically linear, and the dynamic response speed can be improved.

Description

Technical Field

[0001] The invention relates to the technical field of power electronic conversion, and in particular to a switching loss optimization control method and system for an energy storage DC converter. Background Art

[0002] In recent years, the application of energy storage systems has been a hot topic in the field of power electronics, and has been widely used in microgrids, electric vehicle charging, outdoor mobile power supplies, etc. Among the many power electronic DC-DC converter topologies, the dual active bridge (DAB) circuit is a hot topic in related fields because of its wide gain range, electrical isolation, bidirectional energy flow, symmetrical structure, and flexible control. It is suitable for the main application requirements of energy storage systems.

[0003] At present, the control method of dual active bridge circuit generally adopts phase shift control, which reduces current stress and realizes soft switching by adjusting multiple degrees of freedom in triple phase shift control. In efficiency optimization analysis, the Lagrange multiplier method is often used to calculate the minimum effective value of the inductor current. However, the optimal solution obtained by this method may have phase shift jumps under different working conditions, increase control complexity, and affect dynamic performance.

[0004] In order to reduce the complexity of the control system and improve the practicality of the dual active bridge circuit control method, there is a Chinese patent with publication number CN107968571A that discloses a triple phase shift control method, which achieves the optimal solution for current stress through a single control loop. Another example is the Chinese patent with publication number CN113364298A, which uses a resonant dual active bridge topology, combined with frequency modulation control and single phase shift control, to achieve soft switching in the full power range. The Chinese patent with publication number CN118473227A optimizes the current stress separately according to different operating powers and achieves the continuity of the control system.

[0005] Although the above patents optimize the current stress of the dual active bridge circuit, or broaden the soft switching range of the dual active bridge circuit, and reduce the complexity of control, they often do not consider the circuit shutdown loss. In the low-voltage user energy storage scenario, due to the large current on the low-voltage side, the loss caused by device shutdown accounts for a much larger proportion than reactive circulating current and hard switching, so the relevant control methods are still insufficient. Summary of the invention

[0006] In order to solve the deficiencies in the prior art, the present invention provides a control method and system for optimizing the efficiency of a dual active bridge converter in the full power range. The present invention combines triple phase shift control and frequency modulation control to optimize switching loss and reactive circulating current in the bidirectional full power range.

[0007] The technical solution of the present invention is:

[0008] 1. A method for optimizing the control of switching losses of an energy storage DC converter

[0009] Step 1: Obtain the battery side voltage / current and bus side voltage / current of the energy storage DC converter;

[0010] Step 2: Calculate the voltage ratio between the two sides of the energy storage DC converter according to the battery side voltage and the bus side voltage;

[0011] Step 3: Calculate the control power P based on the battery side voltage / current and bus side voltage / current * ;

[0012] Step 4: Using the energy storage DC converter to control the power P * Determine the operating modes of the dual active bridge circuit;

[0013] Step 5: According to the working mode of the dual active bridge circuit, the actual power size of the dual active bridge circuit is adjusted to complete the switching loss optimization of the energy storage DC converter.

[0014] The voltage ratio m on both sides of the energy storage DC converter satisfies the following formula:

[0015] When bat <V bus hour

[0016] When bat >V bus hour

[0017] Among them, V bat is the battery side voltage, V bus is the bus side voltage, and n is the turns ratio between the secondary and primary sides of the isolation transformer T in the energy storage DC converter.

[0018] The working modes of the dual active bridge circuit include a first mode, a second mode, a third mode and a fourth mode, and the specific determination method is as follows:

[0019] According to the current control power P * Calculate and obtain the corresponding external phase shift angle, bridge arm midpoint voltage duty cycle k, switching frequency, power flow direction, and power size, wherein the bridge arm midpoint voltage duty cycle k is the duty cycle of the lower voltage side between the battery side and the bus side of the transformer;

[0020] If the power of the current dual active bridge circuit is less than the first preset power, the working mode of the dual active bridge circuit is the first mode;

[0021] If the current external phase angle absolute value |D|>k*(1-m) / 2 and the bridge arm midpoint voltage duty cycle k is less than the preset maximum duty cycle k max When , the working mode of the dual active bridge circuit is the second mode;

[0022] If the current bridge arm midpoint voltage duty cycle k is equal to the preset maximum duty cycle k max And the switching frequency is less than the preset maximum switching frequency f max When , the working mode of the dual active bridge circuit is the third mode;

[0023] If the current switching frequency is equal to the preset minimum switching frequency f min When , the working mode of the dual active bridge circuit is the fourth mode.

[0024] When the working mode of the dual active bridge circuit is the first mode, the bridge arm midpoint voltage duty cycle k is equal to the preset minimum duty cycle k min , switching frequency f s Equal to the preset maximum switching frequency f max , by adjusting the external phase shift angle D, the actual power size of the dual active bridge circuit can be changed.

[0025] When the working mode of the dual active bridge circuit is the second mode, the switching frequency f s Equal to the preset maximum switching frequency f max By adjusting the bridge arm midpoint voltage duty cycle k, the actual power size and external shift phase angle of the dual active bridge circuit are adjusted, and finally the dual active bridge circuit works in a soft switching state.

[0026] When the working mode of the dual active bridge circuit is the third mode, the current bridge arm midpoint voltage duty cycle k is equal to the preset maximum duty cycle k max , by adjusting the switching frequency f s To adjust the power.

[0027] When the working mode of the dual active bridge circuit is the fourth mode, the switching frequency f s Equal to the preset minimum switching frequency f min , the actual power of the dual active bridge circuit is adjusted by adjusting the external phase shift angle D until it reaches full load.

[0028] The internal phase shift angle on the battery side is d1, and the internal phase shift angle on the bus side is d2. The formula is as follows:

[0029] When bat >V bus hour

[0030] When bat <V bus hour

[0031] Where m is the voltage ratio on both sides of the energy storage DC converter, V bat is the battery side voltage, V bus is the bus side voltage, and n is the turns ratio between the secondary and primary sides of the isolation transformer T in the energy storage DC converter.

[0032] 2. A Switching Loss Optimization Control System for Energy Storage DC Converters

[0033] A voltage and current acquisition unit, used to acquire the battery side voltage / current and bus side voltage / current of the energy storage DC converter;

[0034] A voltage ratio calculation unit, used to calculate the voltage ratio between the two sides of the energy storage DC converter according to the battery side voltage and the bus side voltage;

[0035] The control power calculation unit is used to calculate the control power P according to the battery side voltage / current and the bus side voltage / current * ;

[0036] Working mode judgment unit, used to control power P of energy storage DC converter * Determine the operating modes of the dual active bridge circuit;

[0037] The power regulating unit regulates the actual power of the dual active bridge circuit according to the working mode of the dual active bridge circuit.

[0038] Compared with the prior art, the beneficial effects of the present invention include:

[0039] (1) The continuous control of the dual active bridge converter in the bidirectional full power range is realized;

[0040] (2) Combining triple phase shift control with frequency modulation control reduces turn-off loss and improves circuit efficiency;

[0041] (3) The control object is simplified, and a single controller is used for different working conditions, which is suitable for engineering practice;

[0042] (4) Power linearization processing speeds up the loop speed and improves dynamic performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0044] Figure 1 This is a circuit topology diagram of the energy storage DC converter provided by the present invention.

[0045] Figure 2 This is a control block diagram of the control method provided by the present invention.

[0046] Figure 3 This is a schematic diagram of the changes in various degrees of freedom under different modes in the control method provided by the present invention.

[0047] Figure 4 The switching timing and key waveform diagram of the first embodiment mode provided by the present invention.

[0048] Figure 5 The switching timing and key waveform diagram of mode 2 of the embodiment provided by the present invention.

[0049] Figure 6 The switching timing and key waveform diagram of mode three of the embodiment provided by the present invention.

[0050] Figure 7 The switching timing and key waveform diagram of mode 4 of the embodiment provided by the present invention. DETAILED DESCRIPTION

[0051] Embodiments of the present invention are described in detail below, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. The described embodiments are intended only to facilitate the understanding of the present invention, and do not have any limiting effect on it.

[0052] In the following description, "circuit" refers to a conductive loop composed of at least one element or subcircuit through electrical connection or electromagnetic connection. When an element or circuit is said to be "coupled to" or "connected to" another element or an element / circuit is said to be "coupled to" or "connected to" two nodes, it can be directly coupled or connected to another element or there can be an intermediate element, and the connection between the elements can be physical, logical, or a combination thereof. Conversely, when an element is said to be "directly connected to" another element, it means that there is no intermediate element between the two.

[0053] An embodiment of the present invention provides an energy storage DC converter, whose circuit topology adopts a dual active bridge converter. Figure 1 The dual active bridge circuit includes a battery-side voltage stabilizing capacitor C bat , Bus side voltage stabilizing capacitor C bus , a battery-side H-bridge circuit including switch tubes S1 to S4, a bus-side H-bridge circuit including switch tubes S5 to S8, a high-frequency isolation transformer T with a turns ratio of 1:n, and a resonant inductor L r and resonant capacitor C r .

[0054] For each H-bridge circuit, the upper and lower switches are complementary and turned on. When one control signal is determined, the other control signal of the same bridge arm is also uniquely determined. The signals of switch S1 and switch S2 are complementary, the signals of switch S3 and switch S4 are complementary, the signals of switch S5 and switch S6 are complementary, and the signals of switch S7 and switch S8 are complementary.

[0055] The internal phase shift angle on the battery side is specified as d1, and the internal phase shift angle on the bus side is specified as d2. The value range of the two is [0,1]. In the fundamental wave analysis, they are used to adjust the midpoint voltage v of the battery side bridge arm. ab and bus side bridge arm midpoint voltage v cd When the inner phase shift angle is 0, the corresponding bridge arm midpoint voltage duty cycle is 1. When the inner phase shift angle is 1, the corresponding bridge arm midpoint voltage duty cycle is 0, that is, there is no conduction moment.

[0056] The bridge arm midpoint voltage v is specified ab and v cd The voltage phase angle difference is the outward phase angle D. When the midpoint voltage of the battery side bridge arm v ab Lagging behind the bus side bridge arm midpoint voltage v cd When the external phase angle D is positive, the power flows from the battery side to the bus side, and it works in the discharge state; when the midpoint voltage of the battery side bridge arm v ab Leading the bus side bridge arm midpoint voltage v cd When , the external phase angle D is negative, power flows from the bus side to the battery side, and it works in the charging state.

[0057] The switching frequency f of all 8 switches in the dual active bridge circuit s They are exactly the same at the same time and change simultaneously in the frequency modulation control mode. At this time, the internal and external phase shift angles do not change.

[0058] Since the working conditions of the circuit when transmitting power in the forward direction and the reverse direction are similar, the present invention only introduces the situation when power flows from the battery side to the bus side, that is, in the discharge state.

[0059] In order to clearly demonstrate the optimization of switching loss by the present invention, this embodiment selects the case where the voltage difference after the voltage conversion on both sides is large. In the existing dual active bridge circuit control technology, the shutdown current under this condition is very large, and the loss caused by the shutdown of the low-voltage side device accounts for a much larger proportion than the reactive circulating current and hard opening. The optimization of efficiency by the control method proposed by the present invention is more obvious in this embodiment.

[0060] The control block diagram used in this embodiment is as follows Figure 2As shown, it includes a voltage difference comparator, a voltage PI controller, a current difference comparator, a current PI controller, a phase shift angle calculation module and a drive signal generation module connected in sequence. Among them, the control object of the voltage outer loop can select the battery voltage and the bus voltage according to the charging and discharging state, and the voltage outer loop obtains the current reference value I through PI control output. * ;Current loop control object selection Figure 1 The battery voltage I bat The current loop is controlled by PI to output the control signal P * , and then obtain the corresponding inner phase shift angles d1, d2 and outer phase shift angle D under the current power through the phase shift angle calculation module, and determine the corresponding switching frequency f s , and finally generate a control signal through the driving signal generating module.

[0061] The specific steps include:

[0062] Step 1: Collect and obtain the battery side voltage / current and bus side voltage / current of the energy storage DC converter;

[0063] Step 2: Calculate the voltage ratio between the two sides of the energy storage DC converter according to the battery side voltage and the bus side voltage;

[0064] The voltage ratio m on both sides of the energy storage DC converter satisfies the following formula:

[0065] When bat <V bus hour

[0066] When bat >V bus hour

[0067] Among them, V bat is the battery side voltage, V bus is the bus side voltage, and n is the turns ratio between the secondary and primary sides of the isolation transformer T in the energy storage DC converter.

[0068] In the present invention, the internal and external phase shift angles and switching frequency of the circuit are determined according to the output signal of the controller. In order to facilitate the control of the degree of freedom, the variable k is introduced to represent the duty cycle of the midpoint voltage of the bridge arm, and the fundamental wave matching is performed according to the calculated voltage ratio to reduce the reactive circulating current. Let the internal phase shift angle on the battery side be d1, and the internal phase shift angle on the bus side be d2. The corresponding calculation formula is as follows:

[0069] When bat >V bus hour

[0070] When bat <Vbus hour

[0071] Where m is the voltage ratio on both sides of the energy storage DC converter, V bat is the battery side voltage, V bus is the bus side voltage, and n is the turns ratio between the secondary and primary sides of the isolation transformer T in the energy storage DC converter.

[0072] Step 3: Calculate the control power P based on the battery side voltage / current and bus side voltage / current * ;

[0073] Step 4: Using the energy storage DC converter to control the power P * Determine the operating modes of the dual active bridge circuit;

[0074] The working modes of the dual active bridge circuit include the first mode, the second mode, the third mode and the fourth mode. The specific judgment method is as follows:

[0075] According to the current control power P * The corresponding external phase shift angle, bridge arm midpoint voltage duty cycle k, switching frequency, power flow direction, and power size are calculated. The bridge arm midpoint voltage duty cycle k is the duty cycle of the lower voltage side between the battery side and the bus side of the transformer, that is, the duty cycle of the higher side is k*m;

[0076] If the power of the current dual active bridge circuit is less than the first preset power (which is equal to the circuit power corresponding to the external phase shift angle k*(1-m) / 2), the working mode of the dual active bridge circuit is the first mode;

[0077] If the current external phase angle absolute value |D|>k*(1-m) / 2 and the bridge arm midpoint voltage duty cycle k is less than the preset maximum duty cycle k max When , the working mode of the dual active bridge circuit is the second mode;

[0078] If the current bridge arm midpoint voltage duty cycle k is equal to the preset maximum duty cycle k max And the switching frequency is less than the preset maximum switching frequency f max When , the working mode of the dual active bridge circuit is the third mode;

[0079] If the current switching frequency is equal to the preset minimum switching frequency f min When , the working mode of the dual active bridge circuit is the fourth mode.

[0080] Step 5: According to the working mode of the dual active bridge circuit, the actual power size of the dual active bridge circuit is adjusted to optimize the switching loss of the energy storage DC converter, specifically, the turn-off loss of the switch tube in the dual active bridge circuit is effectively reduced within the full power range.

[0081] The present invention divides the circuit operation into four modes according to the output signal of the controller, so the circuit operation mode is related to the actual power. Among them, mode 1 and mode 4 only control the positive and negative and size of the outer phase shift angle; mode 2 only controls the inner phase shift angle, but in order to ensure the realization of soft switching, the outer phase shift angle changes with the change of the inner phase shift angle; mode 3 only adjusts the switching frequency, such as Figure 3 shown.

[0082] Specifically:

[0083] When the working mode of the dual active bridge circuit is the first mode, that is, the power is close to zero, in order to ensure the positive and negative continuity of the current, the bridge arm midpoint voltage duty cycle k is equal to the preset minimum duty cycle k min , switching frequency f s Equal to the preset maximum switching frequency f max , by adjusting the external phase shift angle D, the actual power of the dual active bridge circuit can be adjusted. At this time, the switching timing of each switch tube and the bridge arm midpoint voltage v ab and v cd , the inductor current waveform is as follows Figure 4 shown.

[0084] When the working mode of the dual active bridge circuit is the second mode, the six switch tubes in the circuit can realize soft switching. At this time, continuing to increase the external phase angle will increase the turn-off loss, but will not reduce the turn-on loss. Therefore, the external phase angle is stopped. The external phase angle D is equal to k*(1-m) / 2, and the switching frequency f s Equal to the preset maximum switching frequency f max By adjusting the bridge arm midpoint voltage duty cycle k, the actual power size and external phase shift angle of the dual active bridge circuit are adjusted. The external phase shift angle is changed due to the adjustment of the voltage duty cycle k, and finally the dual active bridge circuit continues to work in the soft switching state. At this time, the switching timing of each switch tube and the bridge arm midpoint voltage v ab and v cd , the inductor current waveform is as follows Figure 5 shown.

[0085] When the working mode of the dual active bridge circuit is the third mode, the circuit power cannot be increased by further increasing k. When the current bridge arm midpoint voltage duty cycle k is equal to the preset maximum duty cycle k max , thus determining the external phase angle D, that is, D = k max *(1-m) / 2, by adjusting the switching frequency f s To adjust the power. At this time, the switching timing of each switch tube and the bridge arm midpoint voltage v ab and v cd , the inductor current waveform is as follows Figure 6 shown.

[0086] When the dual active bridge circuit works in the fourth mode, when the switching frequency is reduced to close to the resonant frequency, the current waveform shows obvious resonance, and the switch-off current is significantly reduced. However, further reducing the frequency will lead to a resonant state, and the circuit working state will change. Switching frequency f s Equal to the preset minimum switching frequency f min , the actual power of the dual active bridge circuit is adjusted by adjusting the external phase shift angle D until it reaches full load. At this time, all the switches in the circuit can achieve soft switching, and the turn-off current is small. At this time, the switching timing of each switch tube and the bridge arm midpoint voltage v ab and v cd , the inductor current waveform is as follows Figure 7 shown.

[0087] When the battery side voltage, bus side voltage and load power of the circuit change, the output signal of the controller can change continuously, achieving a smooth transition between various working modes, and the output signal is basically linear with the power gain, which can improve the dynamic response speed.

[0088] The present invention also proposes a switching loss optimization control system for an energy storage DC converter, the system comprising:

[0089] A voltage and current acquisition unit, used to acquire the battery side voltage / current and bus side voltage / current of the energy storage DC converter;

[0090] A voltage ratio calculation unit, used to calculate the voltage ratio between the two sides of the energy storage DC converter according to the battery side voltage and the bus side voltage;

[0091] The control power calculation unit is used to calculate the control power P according to the battery side voltage / current and the bus side voltage / current * ;

[0092] Working mode judgment unit, used to control power P of energy storage DC converter * Determine the operating modes of the dual active bridge circuit;

[0093] The power regulating unit regulates the actual power of the dual active bridge circuit according to the working mode of the dual active bridge circuit.

[0094] In some embodiments, the working conditions of the circuit are different from those in this embodiment, so the boundaries and key waveforms of each working mode are different. However, the control methods of the embodiments described in the present invention are essentially the same as those of other embodiments and all belong to the protection scope of the present invention.

[0095] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A switching loss optimization control method for an energy storage DC converter, characterized in that: The following steps are involved: Step 1: Obtain the battery side voltage / current and bus side voltage / current of the energy storage DC converter; Step 2: Calculate the voltage ratio between the two sides of the energy storage DC converter according to the battery side voltage and the bus side voltage; Step 3: Calculate the control power P based on the battery side voltage / current and bus side voltage / current * ; Step 4: Using the energy storage DC converter to control the power P * Determine the operating modes of the dual active bridge circuit; Step 5: According to the working mode of the dual active bridge circuit, the actual power size of the dual active bridge circuit is adjusted to complete the switching loss optimization of the energy storage DC converter.

2. The switching loss optimization control method of an energy storage DC converter according to claim 1, characterized in that: The voltage ratio m on both sides of the energy storage DC converter satisfies the following formula: When bat <V bus hour When bat >V bus hour Among them, V bat is the battery side voltage, V bus is the bus side voltage, and n is the turns ratio between the secondary and primary sides of the isolation transformer T in the energy storage DC converter.

3. The switching loss optimization control method of an energy storage DC converter according to claim 1, characterized in that: The working modes of the dual active bridge circuit include a first mode, a second mode, a third mode and a fourth mode, and the specific determination method is as follows: According to the current control power P * Calculate and obtain the corresponding external phase shift angle, bridge arm midpoint voltage duty cycle k, switching frequency, power flow direction, and power size, wherein the bridge arm midpoint voltage duty cycle k is the duty cycle of the lower voltage side between the battery side and the bus side of the transformer; If the power of the current dual active bridge circuit is less than the first preset power, the working mode of the dual active bridge circuit is the first mode; If the current external phase angle absolute value |D|>k*(1-m) / 2 and the bridge arm midpoint voltage duty cycle k is less than the preset maximum duty cycle k max When , the working mode of the dual active bridge circuit is the second mode; If the current bridge arm midpoint voltage duty cycle k is equal to the preset maximum duty cycle k max And the switching frequency is less than the preset maximum switching frequency f max When , the working mode of the dual active bridge circuit is the third mode; If the current switching frequency is equal to the preset minimum switching frequency f min When , the working mode of the dual active bridge circuit is the fourth mode.

4. The switching loss optimization control method of an energy storage DC converter according to claim 3 is characterized in that: When the working mode of the dual active bridge circuit is the first mode, the bridge arm midpoint voltage duty cycle k is equal to the preset minimum duty cycle k min , switching frequency f s Equal to the preset maximum switching frequency f max , by adjusting the external phase shift angle D, the actual power size of the dual active bridge circuit can be changed.

5. The switching loss optimization control method of an energy storage DC converter according to claim 3 is characterized in that: When the working mode of the dual active bridge circuit is the second mode, the switching frequency f s Equal to the preset maximum switching frequency f max By adjusting the bridge arm midpoint voltage duty cycle k, the actual power size and external shift phase angle of the dual active bridge circuit are adjusted, and finally the dual active bridge circuit works in a soft switching state.

6. The switching loss optimization control method of an energy storage DC converter according to claim 3 is characterized in that: When the working mode of the dual active bridge circuit is the third mode, the current bridge arm midpoint voltage duty cycle k is equal to the preset maximum duty cycle k max , by adjusting the switching frequency f s To adjust the power.

7. The switching loss optimization control method of an energy storage DC converter according to claim 3, characterized in that: When the working mode of the dual active bridge circuit is the fourth mode, the switching frequency f s Equal to the preset minimum switching frequency f min , the actual power of the dual active bridge circuit is adjusted by adjusting the external phase shift angle D until it reaches full load.

8. The switching loss optimization control method of an energy storage DC converter according to claim 1, characterized in that: The internal phase shift angle on the battery side is d1, and the internal phase shift angle on the bus side is d2. The formula is as follows: When bat >V bus hour When bat <V bus hour Where m is the voltage ratio on both sides of the energy storage DC converter, V bat is the battery side voltage, V bus is the bus side voltage, and n is the turns ratio between the secondary and primary sides of the isolation transformer T in the energy storage DC converter.

9. A switching loss optimization control system for an energy storage DC converter, characterized in that: include: A voltage and current acquisition unit, used to acquire the battery side voltage / current and bus side voltage / current of the energy storage DC converter; A voltage ratio calculation unit, used to calculate the voltage ratio between the two sides of the energy storage DC converter according to the battery side voltage and the bus side voltage; The control power calculation unit is used to calculate the control power P according to the battery side voltage / current and the bus side voltage / current * ; Working mode judgment unit, used to control power P of energy storage DC converter * Determine the operating modes of the dual active bridge circuit; The power regulating unit regulates the actual power of the dual active bridge circuit according to the working mode of the dual active bridge circuit.

Images