Dual-active full-bridge converter control method, system and device and storage medium

Abstract

The invention relates to the technical field of converter control, and provides a dual-active full-bridge converter control method, system and device and a storage medium, the dual-active full-bridge converter comprises a primary side and a secondary side, and the method comprises the following steps: S1, determining a phase shift control mode of each working mode when the dual-active full-bridge converter performs multiple phase shift control; s2, based on the phase shift control mode and the excitation current peak value of each working mode, calculating a primary side inner phase shift duty ratio and a secondary side inner phase shift duty ratio corresponding to each working mode and a switching condition between different working modes; and S3, performing control based on the primary side inner phase shift duty ratio and the secondary side inner phase shift duty ratio corresponding to each working mode and switching conditions among different working modes. According to the method, the influence of excitation inductance is considered when the multi-phase-shift control is performed on the dual-active full-bridge converter, reactive current under the multi-phase-shift control can be effectively reduced, and the efficiency of the system is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of converter control, and in particular to a dual-active full-bridge converter control method, system, device and storage medium. Background Art

[0002] The Dual-Active Bridge Converter (DAB) has been widely used in medium-voltage DC transmission, energy storage and other fields that require bidirectional power conversion. The dual-active full-bridge converter is controlled by multiple phase-shift control technology. The inductor current waveform of the dual-active full-bridge converter can be flexibly changed when the converter is running under light load, achieving zero-voltage turn-on of the converter switch tube, reducing the stress of the switching device, and improving operational reliability.

[0003] However, existing dual-active full-bridge converter multi-phase-shift control strategies do not consider the transformer's magnetizing inductance. This inductance generates excitation currents that prevent the dual-active full-bridge converter from accurately controlling the voltage and current at the switching points when using multi-phase-shift control. This results in excessive reactive current within the converter resonant cavity, reducing converter efficiency. Summary of the Invention

[0004] In order to solve the above-mentioned technical problems, the present invention provides a dual-active full-bridge converter control method, system, device and storage medium. When calculating the phase-shift duty cycle within the primary side and the phase-shift duty cycle within the secondary side corresponding to each working mode and the switching conditions between different working modes, the influence of the excitation inductance is taken into account, which can effectively reduce the reactive current under multiple phase-shift control and improve the efficiency of the system.

[0005] The technical solution adopted in the present invention is as follows:

[0006] A method for controlling a dual-active full-bridge converter, the dual-active full-bridge converter including a primary side and a secondary side, the method comprising: S1, determining a phase-shift control mode for each operating mode when the dual-active full-bridge converter performs multiple phase-shift control; S2, calculating, based on the phase-shift control mode for each operating mode and the peak value of the excitation current of the dual-active full-bridge converter, a primary-side phase-shift duty cycle and a secondary-side phase-shift duty cycle corresponding to each operating mode, as well as switching conditions between different operating modes; S3, controlling the dual-active full-bridge converter based on the primary-side phase-shift duty cycle and the secondary-side phase-shift duty cycle corresponding to each operating mode, as well as switching conditions between different operating modes.

[0007] In addition, the dual-active full-bridge converter control method proposed above according to the present invention may also have the following additional technical features:

[0008] According to one embodiment of the present invention, the excitation current peak value iLm_max The calculation formula is:

[0009]

[0010] Where n is the transformer ratio in the dual active full-bridge converter, V bat is the output voltage, d T is the duty cycle coefficient, and its calculation formula is d T =2-d s +d,d s is the phase shift duty cycle inside the secondary side, d is the phase shift duty cycle outside the original secondary side, L m is the magnetizing inductance, f s is the switching frequency.

[0011] According to an embodiment of the present invention, the multiple phase-shift control is a composite multiple phase-shift control including single phase-shift control, double phase-shift control and triple phase-shift control.

[0012] According to one embodiment of the present invention, in step S1, the phase shift control mode of each working mode is determined under different voltage control states when the dual active full-bridge converter performs multiple phase shift control, and the voltage control state includes step-down phase shift control and step-up phase shift control.

[0013] According to one embodiment of the present invention, when the dual-active full-bridge converter is in step-down phase-shift control, the switchable operating modes include a first triple phase-shift mode, a first primary-side double phase-shift mode, a second primary-side double phase-shift mode, a third primary-side double phase-shift mode, and a single phase-shift mode; when the dual-active full-bridge converter is in step-up phase-shift control, the switchable operating modes include a single phase-shift mode, a first secondary-side double phase-shift mode, a second secondary-side double phase-shift mode, a third secondary-side double phase-shift mode, and a second triple phase-shift mode.

[0014] According to one embodiment of the present invention, when the dual active full-bridge converter switches between boost phase-shift control and buck phase-shift control, it switches between the second primary dual phase-shift mode and the second secondary dual phase-shift mode.

[0015] According to one embodiment of the present invention, step S3 specifically includes: according to the current operating mode of the dual-active full-bridge converter and the primary-secondary side external phase shift duty cycle, based on the switching conditions between the different operating modes, obtaining the next operating mode of the dual-active full-bridge converter; based on the primary side internal phase shift angle and the secondary side internal phase shift angle corresponding to the next operating mode, controlling the dual-active full-bridge converter.

[0016] In addition, to achieve the above objectives, the present invention also proposes a dual active full-bridge converter control system.

[0017] A dual-active full-bridge converter control system, the dual-active full-bridge converter including a primary side and a secondary side, comprising: a mode determination module, the mode determination module being used to determine the phase-shift control mode for each operating mode when the dual-active full-bridge converter performs multiple phase-shift control; a calculation module, the calculation module calculating, based on the phase-shift control mode for each operating mode and the excitation current peak value of the dual-active full-bridge converter, the primary side phase-shift duty cycle and the secondary side phase-shift duty cycle corresponding to each operating mode, as well as the switching conditions between different operating modes; and a control module, the control module controlling the dual-active full-bridge converter based on the primary side phase-shift duty cycle and the secondary side phase-shift duty cycle corresponding to each operating mode, as well as the switching conditions between the different operating modes.

[0018] In addition, to achieve the above-mentioned purpose, the present invention also provides an electronic device.

[0019] An electronic device includes a memory, a processor, and a dual-active full-bridge converter control program stored in the memory and executable on the processor. When the processor executes the dual-active full-bridge converter control program, the dual-active full-bridge converter control method described above is implemented.

[0020] In addition, to achieve the above-mentioned purpose, the present invention also provides a storage medium.

[0021] A storage medium stores a dual active full-bridge converter control program, and when the computer program is executed by a processor, the dual active full-bridge converter control program described above is implemented.

[0022] Beneficial effects of the present invention:

[0023] The dual-active full-bridge converter control method of the present invention takes into account the excitation current peak, that is, the influence of the excitation inductance on the reactive current, when calculating the phase-shift duty cycle within the primary side and the phase-shift duty cycle within the secondary side corresponding to each operating mode and the switching conditions between different operating modes. This is beneficial for the switching tubes on both sides to ensure that the reactive current of the resonant cavity is minimized while achieving soft switching, thereby improving the efficiency of the converter. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is the topology diagram of the dual active bridge converter;

[0025] Figure 2 Flowchart of a dual active full-bridge converter control method according to an embodiment of the present invention;

[0026] Figure 3 A schematic diagram of operating mode switching under multiple phase-shift control according to an embodiment of the present invention;

[0027] Figure 4is a switching mode diagram of a first triple phase-shift mode according to an embodiment of the present invention;

[0028] Figure 5 This is a switching mode diagram of the first primary-side double-phase-shifted mode according to an embodiment of the present invention;

[0029] Figure 6 This is a switching mode diagram of the second primary-side double-phase-shifted mode according to an embodiment of the present invention;

[0030] Figure 7 This is a switching mode diagram of the third primary-side double-phase-shifted mode according to an embodiment of the present invention;

[0031] Figure 8 A switching mode diagram of a single phase-shift mode according to an embodiment of the present invention;

[0032] Figure 9 This is a switching mode diagram of the first secondary side double phase-shift mode according to an embodiment of the present invention;

[0033] Figure 10 This is a switching mode diagram of the second secondary side double phase shift mode according to an embodiment of the present invention;

[0034] Figure 11 This is a switching mode diagram of the third secondary side double phase-shift mode according to an embodiment of the present invention;

[0035] Figure 12 is a switching mode diagram of the second triple phase-shift mode according to an embodiment of the present invention;

[0036] Figure 13 A schematic diagram of operating mode switching under multiple phase shift control according to another embodiment of the present invention;

[0037] Figure 14 4 is a block diagram of a dual active full-bridge converter control system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0039] like Figure 1 As shown, the common dual active full-bridge converter includes a primary side and a secondary side, both of which are active full-bridge circuits. The primary side is the input side, the secondary side is the output side, P1 to P4 are primary side switches, S1 to S4 are secondary side switches, and the switching frequency of each switch is the same as f s , Vdc is the input voltage on the primary side, V bat is the output voltage on the secondary side, n is the transformation ratio of transformer T, L r is the inductance of the resonant inductor, L m is the inductance of the excitation inductor, i r is the current flowing through the excitation inductor, d is the duty cycle of the primary and secondary side outward phase shift, d p is the duty cycle of the phase shift in the primary side, d s is the phase shift duty cycle in the secondary side, A and B are the AC interfaces of the primary side H bridge, C and D are the AC interfaces of the secondary side H bridge, V AB is the voltage between interface A and interface B, V CD is the voltage between the C interface and the D interface.

[0040] like Figure 2 As shown, the dual active full-bridge converter control method according to an embodiment of the present invention includes:

[0041] S1, determining a phase shift control mode for each operating mode when the dual-active full-bridge converter performs multiple phase shift control. Specifically, the multiple phase shift control may be a composite multiple phase shift control including single phase shift control, double phase shift control, and triple phase shift control.

[0042] In one embodiment of the present invention, a dual-active full-bridge converter has multiple different operating modes under different voltage control states, where the voltage control states may include buck phase-shift control and boost phase-shift control. Therefore, in step S1, it is necessary to determine the phase-shift control method for each operating mode under different voltage control states when the dual-active full-bridge converter performs multiple phase-shift control. In other embodiments of the present invention, multiple phase-shift control may be performed only under buck phase-shift control, or only under boost phase-shift control, and this embodiment is not limiting.

[0043] S2, based on the phase-shift control method of each working mode and the excitation current peak of the dual-active full-bridge converter, calculates the phase-shift duty cycle in the primary side and the phase-shift duty cycle in the secondary side corresponding to each working mode, as well as the switching conditions between different working modes.

[0044] It is understandable that when the transformer's transformation ratio is greater than 1, conventional multiple phase-shift control only considers the resonant current conditions for the primary-side switch tube to achieve soft switching. Therefore, triple phase-shift control can result in excessive reactive current on one side of the switch tube. When the transformer's transformation ratio is less than 1, the current used by the secondary-side switch tube to achieve soft switching is less than the expected value, making it impossible to achieve complete soft switching. However, the present invention considers the excitation current peak, i.e., the effect of the excitation inductance on the reactive current, when calculating the primary-side and secondary-side phase-shift duty cycles corresponding to each operating mode, as well as the switching conditions between different operating modes. This facilitates both sides of the switch tube to achieve soft switching while minimizing the reactive current in the resonant cavity, thereby improving converter efficiency.

[0045] Optionally, the excitation current peak value i Lm_max The calculation formula is:

[0046]

[0047] Where n is the transformer ratio in the dual active full-bridge converter, V bat is the output voltage, d T is the duty cycle coefficient, and its calculation formula is d T =2-d s +d,d s is the phase shift duty cycle inside the secondary side, d is the phase shift duty cycle outside the original secondary side, L m is the magnetizing inductance, f s is the switching frequency.

[0048] S3, controlling the dual active full-bridge converter based on the phase-shifted duty cycle in the primary side and the phase-shifted duty cycle in the secondary side corresponding to each working mode and the switching conditions between different working modes.

[0049] In one embodiment of the present invention, step S3 may specifically include the following steps S31 and S32:

[0050] S31 , according to the current operating mode of the dual-active full-bridge converter and the primary-secondary side external phase shift duty cycle, based on the switching conditions between different operating modes, obtain the next operating mode of the dual-active full-bridge converter.

[0051] It can be understood that by using the duty cycle of the primary and secondary side external phase shift as the basis for judging the switching between different working modes, compared with the traditional multiple phase shift control based on the change of transmission power as the judgment criterion, the mode switching can be achieved more smoothly and the output characteristics of the system can be improved.

[0052] S32 , controlling the dual active full-bridge converter based on the primary side internal phase shift angle and the secondary side internal phase shift angle corresponding to the next operating mode.

[0053] like Figure 3As shown, in one embodiment of the present invention, the voltage control state of the dual-active full-bridge converter includes buck phase-shift control and boost phase-shift control, and the multiple phase-shift control is a composite multiple phase-shift control including single phase-shift control, double phase-shift control and triple phase-shift control. The buck phase-shift control principle and the boost phase-shift control principle of the composite multiple phase-shift control can be referred to patent CN201910940567.X, which will not be repeated here. When the dual-active full-bridge converter is in step-down phase-shift control, the switchable operating modes include the first triple phase-shift mode state0, the first primary double phase-shift mode state1, the second primary double phase-shift mode state2, the third primary double phase-shift mode state3, and the single phase-shift mode state4; when the dual-active full-bridge converter is in step-up phase-shift control, the switchable operating modes include the single phase-shift mode state4, the first secondary double phase-shift mode state5, the second secondary double phase-shift mode state6, the third secondary double phase-shift mode state7, and the second triple phase-shift mode state8. Under this control method, the current value of the transformer primary bridge arm to achieve ZVS (Zero Voltage Switching) is i zvs_p , the current value of the transformer secondary bridge arm to achieve ZVS is i zvs_s .

[0054] In the first triple phase shift mode state0, the waveforms of the primary and secondary bridge arm voltages and the resonant cavity current are as follows: Figure 4 As shown, in this mode, the absolute value of the current when the primary side lagging bridge arm P1 and P2 are turned on is equal to i zvs_p , when all switches on the secondary side are turned on, the absolute value of the current is equal to All switches can achieve ZVS. In the figure, i0 is the switching current value of the secondary switch S1 in state0, i2 is the switching current value of the primary switch P1 in state0, i3 is the switching current value of the primary switch P3 in state0, i7 is the switching current value of the primary switch P4 in state0, i p is the primary leakage inductance current, i Lm is the excitation current, and t0~t8 are the switching moments of the switch tube in one switching cycle.

[0055] The duty cycles of each time period in the first half of the switching cycle are: The primary current i corresponding to each time period p(t) for:

[0056] Primary current at time t2 Primary current at time t3 Primary current at time t4

[0057] Due to the peak excitation current The secondary current i converted to the primary side at time t0 s0_equ for: The secondary current i converted to the primary side at time t4 s4_equ for:

[0058] Depend on i2=I zvs_p We can get:

[0059]

[0060] Depend on We can get:

[0061]

[0062] The switching condition from the first triple phase shift mode state0 to the first primary double phase shift mode state1 can be based on the fact that there is no internal phase shift on the secondary side, i.e. -d-1+d s ≤0 gives:

[0063] In the first primary double phase shift mode state1, the waveforms of the primary and secondary bridge arm voltages and the resonant cavity current are as follows: Figure 5 As shown, the secondary current i converted to the primary side when the secondary side S1 tube is turned on in this stage is s0_equ Less than The absolute value of the current i1 when the primary side P1 tube is turned on is less than i zvs_p ,i s0_equ The ratio with i1 always remains the same. In this mode, the primary side lagging bridge arm and all the bridge arm switches of the secondary side can only achieve quasi-ZVS. In the figure, i0 is the switching current value of the secondary side switch tube S1 in state1, i1 is the switching current value of the primary side switch tube P3 in state1, i2 is the switching current value of the primary side switch tube P3 in state1, i5 is the switching current value of the primary side switch tube P4 in state1, i p is the primary leakage inductance current, i Lm is the excitation current, and t0~t6 are the switching moments of the switch tube in one switching cycle.

[0064] The duty cycles of each time period in the first half of the switching cycle are: The primary current i corresponding to each time period p(t) for:

[0065] Primary current at time t1: Primary current at time t2: Primary current at time t3:

[0066] Since d s =1+d, so the peak value of the excitation current is The secondary current converted to the primary current at time t0 is: The secondary current converted to the primary current at time t3 is:

[0067] Depend on We can get:

[0068] by i s3_equ =-i s0_equ We can get:

[0069] When the primary-secondary phase shift angle changes from negative to positive, the first primary-side dual phase shift mode state1 switches to the second primary-side dual phase shift mode state2. Therefore, the switching condition is: d≥0. zvs_p The switching condition for switching from the first primary double phase-shifted mode state1 to the first triple phase-shifted mode state0 is obtained as follows:

[0070] In the second primary double phase shift mode state2, the waveforms of the primary and secondary bridge arm voltages and the resonant cavity current are as follows: Figure 6 As shown, the absolute value of the current i0 when the primary side P1 tube is turned on is less than i zvs_p , the secondary current i converted to the primary side when the secondary side S1 tube is turned on s1_equ Less than In order to ensure seamless connection with the third primary double phase shift mode state3, i0 and i s1_equ The ratio remains unchanged. In this mode, the primary side lagging bridge arm and all the secondary side bridge arm switches can only achieve quasi-ZVS. In the figure, i0 is the switching current value of the primary side switch tube P1 in state2, i1 is the switching current value of the secondary side switch tube S1 in state2, i2 is the switching current value of the primary side switch tube P3 in state2, i5 is the switching current value of the primary side switch tube P4 in state2, i p is the primary leakage inductance current, i Lm is the excitation current, and t0~t6 are the switching moments of the switch tube in one switching cycle.

[0071] The duty cycles of each time period in the first half of the switching cycle are: The corresponding primary current i p(t) for:

[0072]

[0073] Primary current at time t1: Primary current at time t2:

[0074] Primary current at time t3:

[0075] Since d s =1+d, the peak value of the excitation current is The secondary current converted to the primary current at time t1 is:

[0076] From i0 and i s1_equ The ratio always remains the same, that is Available From i3=-i0, we can get:

[0077] Solving the above two formulas together we can get:

[0078] From i0≤-I zvs_p , the switching condition for the second primary double phase-shift mode state2 to the third primary double phase-shift mode state3 is obtained: When the primary-secondary phase shift angle changes from positive to negative, the second primary dual phase shift mode state2 switches to the first primary dual phase shift mode state1 , so the switching condition is: d<0.

[0079] In the third primary double phase shift mode state3, the waveforms of the primary-secondary bridge arm voltage and the resonant cavity current are as follows: Figure 7 As shown, in this mode, when the secondary side S1 tube is turned on, the secondary side current i converted to the primary side is s1_equ Always keep equal All switches can achieve ZVS. In the figure, i0 is the switching current value of the primary switch tube P1 in state3, i1 is the switching current value of the secondary switch tube S1 in state3, i2 is the switching current value of the primary switch tube P3 in state3, i3 is the switching current value of the primary switch tube P2 in state3, i4 is the switching current value of the secondary switch tube S2 in state3, i5 is the switching current value of the primary switch tube P4 in state3, i p is the primary leakage inductance current, i Lm is the excitation current, and t0~t6 are the switching moments of the switch tube in one switching cycle.

[0080] The duty cycles of each time period in the first half of the switching cycle are: The corresponding primary current i p(t) for:

[0081] Primary current at time t1: Primary current at time t2:

[0082] Primary current at time t3:

[0083] From i3=-i0, we can get:

[0084] Since d s =1+d, so the peak value of the excitation current is The secondary current converted to the primary current at time t1 is:

[0085] Depend on Available

[0086] No internal phase shift from the primary side 1-d p ≤0, the switching condition for the third primary side double phase-shift mode state3 to switch to the single phase-shift mode state4 is: From i3<i zvs_p Obtain the switching condition for the third primary double phase shift mode state3 to the second primary double phase shift mode state2

[0087]

[0088] In the single phase shift mode state4, the waveforms of the primary and secondary bridge arm voltages and the resonant cavity current are as follows: Figure 8 As shown, in this mode, all bridge arm switches of the primary and secondary sides achieve ZVS. In the figure, i0 is the switching current value of the primary switch tube P1 in state4, i1 is the switching current value of the secondary switch tube S1 in state4, i2 is the switching current value of the primary switch tube P3 in state4, i3 is the switching current value of the secondary switch tube S2 in state4, i p is the primary leakage inductance current, i Lm is the excitation current, and t0~t4 are the switching moments of the switch tube in one switching cycle.

[0089] The duty cycles of each time period in the first half of the switching cycle are: The corresponding primary current i p(t) for:

[0090] Primary current at time t1: Primary current at time t2:

[0091] Since i2=-i0, we can get

[0092] Since d p =1 and d s =1+d, so the peak value of the excitation current The secondary current converted to the primary current at time t1 is

[0093] In order to ensure that the secondary side switch tube achieves ZVS, when When the phase shift angle in the primary bridge arm is increased, the phase shift angle in the primary bridge arm needs to be increased to maintain The switching condition for switching from the single phase-shifted mode state4 to the third primary side double phase-shifted mode state3 is obtained as follows: In order to ensure that the primary side switch tube achieves ZVS, when i2<i zvs_p When the phase shift angle in the secondary bridge arm is increased, it is necessary to maintain i2=i zvs_p , the critical value of the original secondary side external phase shift duty cycle when the single phase shift mode state4 switches to the first secondary side dual phase shift mode state5 can be obtained as:

[0094]

[0095] In the first secondary side double phase shift mode state5, the waveforms of the primary and secondary side bridge arm voltage and resonant cavity current are as follows: Figure 9 As shown, in this mode, the phase shift angle d in the secondary side p =1, when the primary switch tube P1 is turned on, the primary current i1 is always equal to i zvs_p , all switch tubes can achieve ZVS. In the figure, i0 is the switching current value of the primary switch tube P1 in state5, i1 is the switching current value of the secondary switch tube S1 in state5, i2 is the switching current value of the secondary switch tube S4 in state5, i3 is the switching current value of the primary switch tube P2 in state5, i4 is the switching current value of the secondary switch tube S2 in state5, i5 is the switching current value of the secondary switch tube S3 in state5, i p is the primary leakage inductance current, i Lm is the excitation current, and t0~t6 are the switching moments of the switch tube in one switching cycle.

[0096] The duty cycles of each time period in the first half of the switching cycle are: The primary current i corresponding to each time period p(t) for:

[0097] Primary current at time t1 Primary current at time t2 Primary current at time t3 From i3=-i0=I zvs_p We can get:

[0098] Due to the peak excitation current The secondary current i converted to the primary side at time t1 s1_equ for:

[0099]

[0100] The switching condition from the first secondary side double phase shift mode state5 to the single phase shift mode state4 can be determined by the secondary side having no internal phase shift, i.e., d s -1-d≤0 gives: The switching condition from the first secondary side double phase shift mode state5 to the second secondary side double phase shift mode state6 can be determined by get:

[0101]

[0102] In the second secondary side double phase shift mode state6, the waveforms of the primary and secondary side bridge arm voltage and resonant cavity current are as follows: Figure 10 As shown in the figure, i0 is the switching current value of the primary switch tube P1 in state6, i1 is the switching current value of the secondary switch tube S1 in state6, i2 is the switching current value of the secondary switch tube S4 in state6, i5 is the switching current value of the secondary switch tube S3 in state6, i p is the primary leakage inductance current, i Lm is the excitation current, and t0~t6 are the switching moments of the switch tube in one switching cycle.

[0103] The duty cycles of each time period in the first half of the switching cycle are: The primary current i corresponding to each time period p(t) for:

[0104] Primary current at time t1: Primary current at time t2:

[0105] Primary current at time t3:

[0106] Due to the peak excitation current The secondary current converted to the primary current at time t1 is

[0107] Depend on We can get:

[0108] From i3=-i0, we can get:

[0109] The combined solution can be obtained:

[0110]

[0111] The switching condition from the second secondary side double phase shift mode state6 to the first secondary side double phase shift mode state5 can be determined by i0≤-Izvs_p get: When the original secondary side phase shift angle changes from positive to negative, the second secondary side dual phase shift mode state6 switches to the third secondary side dual phase shift mode state7. Therefore, the switching condition is: d<0.

[0112] In the third secondary side double phase shift mode state7, the waveforms of the primary and secondary side bridge arm voltage and resonant cavity current are as follows: Figure 11 As shown, the secondary current i converted to the primary side when the secondary side S1 tube is turned on in this stage is s0_equ Less than The absolute value of the current i1 when the primary side P1 tube is turned on is less than i zvs_p ,i s0_equ The ratio with i1 always remains the same. In this mode, the secondary leading bridge arm and all the primary bridge arm switches can only achieve quasi-ZVS. In the figure, i0 is the switching current value of the secondary switch tube S1 in state7, i1 is the switching current value of the primary switch tube P1 in state7, i2 is the switching current value of the secondary switch tube S4 in state7, i5 is the switching current value of the secondary switch tube S3 in state7, i p is the primary leakage inductance current, i Lm is the excitation current, and t0~t6 are the switching moments of the switch tube in one switching cycle.

[0113] The duty cycles of each time period in the first half of the switching cycle are: The corresponding primary current i p(t) for:

[0114] Primary current at time t1: Primary current at time t2: Primary current at time t3:

[0115] Due to the peak excitation current The secondary current converted to the primary current at time t0 is The secondary current converted to the primary current at time t3 is

[0116] Depend on We can get:

[0117] by i s3_equ =-i s0_equ We can get:

[0118] The combined solution can be obtained:

[0119] When the original secondary side phase shift angle changes from negative to positive, the third secondary side double phase shift mode state7 switches to the second secondary side double phase shift mode state6, and the switching condition is: d≥0. The switching condition of the third secondary side double phase shift mode state7 to the second triple phase shift mode state8 can be determined by i1<-I zvs_p get:

[0120] In the second triple phase shift mode state8, the waveforms of the primary and secondary bridge arm voltages and the resonant cavity current are as follows: Figure 12 As shown, in this stage, when all the switches on the primary side are turned on, the absolute value of the current is equal to i zvs_p When the secondary leading bridge arm S1 and S2 are turned on, the absolute value of the current is equal to All switches can achieve ZVS. In the figure, i0 is the switching current value of the secondary switch S1 in state8, i1 is the switching current value of the primary switch P4 in state8, i3 is the switching current value of the secondary switch S4 in state8, i7 is the switching current value of the secondary switch S3 in state8, i p is the primary leakage inductance current, i Lm is the excitation current, and t0~t8 are the switching moments of the switch tube in one switching cycle.

[0121] The duty cycles of each time period in the first half of the switching cycle are: The corresponding primary current i p(t) for:

[0122] Primary current at time t1: Primary current at time t3: Primary current at time t4:

[0123] Due to the peak excitation current The secondary current converted to the primary current at time t0 is: The secondary current converted to the primary current at time t4 is:

[0124] Depend on We can get: From i1=-I zvs_p We can get: by i s4_equ =-i s0_equ We can get:

[0125] The combined solution can be obtained:

[0126]

[0127] No internal phase shift from the primary side 1-d p≤0, the switching condition from the second triple phase-shift mode state8 to the third secondary double phase-shift mode state7 is obtained as follows:

[0128] Further, if Figure 13 As shown, when the dual active full-bridge converter switches between boost phase-shift control and buck phase-shift control, it can also switch between the second primary side dual phase-shift mode state2 and the second secondary side dual phase-shift mode state6.

[0129] Since state 2 is a dual phase-shift stage with phase shifting within the primary side, and state 6 is a dual phase-shift stage with phase shifting within the secondary side, the switching boundary between state 2 and state 6 should be a single phase-shift mode. As the output voltage increases, the phase-shift angle within the primary side of state 2 gradually decreases. When it decreases to 0, it enters state 6. If the output voltage increases further, the phase-shift angle within the secondary side gradually increases. Conversely, as the output voltage decreases, the phase-shift angle within the secondary side of state 6 gradually decreases. When it decreases to 0, it enters state 2. If the output voltage decreases further, the phase-shift angle within the primary side gradually increases.

[0130] No internal phase shift from the primary side 1-d p ≤0, the switching condition for the second primary dual phase-shift mode state2 to the second secondary dual phase-shift mode state6 is obtained:

[0131] There is no internal phase shift on the secondary side d s -1-d<0, the switching condition for the second secondary dual phase-shift mode state6 to switch to the second primary dual phase-shift mode state2 is obtained:

[0132]

[0133] The following describes a specific embodiment to illustrate the impact of the dual-active full-bridge converter control method of the present invention on the converter. The specific parameters of the dual-active full-bridge converter are as follows: transformer ratio of 1.2:1, transformer excitation inductance of 900uH, primary inductance of 18uH, primary DC blocking capacitor of 5uF, secondary DC blocking capacitor of 5uF, switching frequency of 100kHz, primary ZVS current of 5A, and secondary ZVS current of 5A.

[0134] Based on the above parameters, a simulation is conducted to compare the comprehensive efficiency of the traditional control method and the dual-active full-bridge converter control method of the present invention. The specific results are shown in Table 1 below. bat is the output voltage, P bat is the output power.

[0135] Table 1

[0136] Load conditions Working mode Traditional control algorithms Control method of the present invention <![CDATA[V bat =250V;P bat =330W]]> state0 90.5％ 91.0％ <![CDATA[V bat =250V;P bat =1980W]]> state1 97.4％ 97.4％ <![CDATA[V bat =250V;P bat =4290W]]> state2 97.7％ 97.7％ <![CDATA[V bat =250V;P bat =4620W]]> state3 97.5％ 97.6％ <![CDATA[V bat =250V;P bat =6600W]]> state4 96.9％ 96.9％ <![CDATA[V bat =425V;P bat =6270W]]> state5 98.0％ 98.1％ <![CDATA[V bat =425V;P bat =5610W]]> state6 98.1％ 98.2％ <![CDATA[V bat =425V;P bat =3960W]]> state7 98.1％ 98.1％ <![CDATA[V bat =425V;P bat =330W]]> state8 89.6％ 90.6％

[0137] It can be seen from Table 1 that, compared with the traditional control algorithm, the dual-active full-bridge converter control method of the present invention has a higher overall efficiency, especially the two triple phase-shift stages, state0 and state8.

[0138] According to the dual-active full-bridge converter control method of the present invention, when calculating the phase-shift duty cycle within the primary side and the phase-shift duty cycle within the secondary side corresponding to each operating mode and the switching conditions between different operating modes, the excitation current peak, that is, the influence of the excitation inductance on the reactive current is taken into account. This is beneficial for the switching tubes on both sides to ensure that the reactive current of the resonant cavity is minimized while achieving soft switching, thereby improving the efficiency of the converter.

[0139] In addition, to achieve the above objectives, the present invention also proposes a dual active full-bridge converter control system.

[0140] like Figure 14 As shown, a dual-active full-bridge converter control system according to an embodiment of the present invention includes: a mode determination module 10, a calculation module 20, and a control module 30. The mode determination module 10 is used to determine the phase-shift control mode for each operating mode of the dual-active full-bridge converter when performing multiple phase-shift control. The calculation module 20 calculates the primary-side phase-shift duty cycle and the secondary-side phase-shift duty cycle corresponding to each operating mode, as well as the switching conditions between different operating modes, based on the phase-shift control mode of each operating mode and the peak excitation current of the dual-active full-bridge converter. The control module 30 controls the dual-active full-bridge converter based on the primary-side phase-shift duty cycle and the secondary-side phase-shift duty cycle corresponding to each operating mode, as well as the switching conditions between different operating modes. The multiple phase-shift control can be a composite multiple phase-shift control including single phase-shift control, double phase-shift control, and triple phase-shift control.

[0141] According to the dual-active full-bridge converter control system of the present invention, when calculating the phase-shift duty cycle within the primary side and the phase-shift duty cycle within the secondary side corresponding to each operating mode and the switching conditions between different operating modes, the excitation current peak, that is, the influence of the excitation inductance on the reactive current is taken into account. This is beneficial for the switching tubes on both sides to ensure that the reactive current of the resonant cavity is minimized while achieving soft switching, thereby improving the efficiency of the converter.

[0142] In one embodiment of the present invention, a dual-active full-bridge converter has multiple different operating modes under different voltage control states, where the voltage control states may include buck phase-shift control and boost phase-shift control. The mode determination module 10 is configured to determine the phase-shift control method for each operating mode under different voltage control states when the dual-active full-bridge converter performs multiple phase-shift control. In other embodiments of the present invention, multiple phase-shift control may be performed only under buck phase-shift control, or only under boost phase-shift control, and this embodiment is not limiting.

[0143] In one embodiment of the present invention, the excitation current peak value i Lm_max The calculation formula is:

[0144]

[0145] Among them, V bat is the output voltage, d T is the duty cycle coefficient, and its calculation formula is d T =2-d s +d,d s is the phase shift duty cycle inside the secondary side, d is the phase shift duty cycle outside the original secondary side, L m is the magnetizing inductance, f s is the switching frequency.

[0146] In one embodiment of the present invention, the control module 30 includes a mode update unit and a control unit. The mode update unit is used to obtain the next operating mode of the dual-active full-bridge converter based on the current operating mode of the dual-active full-bridge converter and the primary-secondary side external phase shift duty cycle based on the switching conditions between different operating modes; the control unit is used to control the dual-active full-bridge converter based on the next operating mode output by the mode update unit and its corresponding primary side internal phase shift angle and secondary side internal phase shift angle.

[0147] It can be understood that the mode update unit uses the duty cycle of the original secondary side external phase shift as the basis for judging the switching between different working modes. Compared with the traditional multiple phase shift control based on the change of transmission power as the judgment criterion, it can achieve mode switching more smoothly and improve the output characteristics of the system.

[0148] In one embodiment of the present invention, the voltage control state of the dual-active full-bridge converter includes buck phase-shift control and boost phase-shift control, and the multiple phase-shift control is a composite multiple phase-shift control including single phase-shift control, double phase-shift control and triple phase-shift control. The buck phase-shift control principle and the boost phase-shift control principle of the composite multiple phase-shift control can be referred to patent CN201910940567.X, which will not be repeated here. When the dual-active full-bridge converter is in step-down phase-shift control, the switchable operating modes include the first triple phase-shift mode state0, the first primary side double phase-shift mode state1, the second primary side double phase-shift mode state2, the third primary side double phase-shift mode state3 and the single phase-shift mode state4; when the dual-active full-bridge converter is in step-up phase-shift control, the switchable operating modes include the single phase-shift mode state4, the first secondary side double phase-shift mode state5, the second secondary side double phase-shift mode state6, the third secondary side double phase-shift mode state7 and the second triple phase-shift mode state8.

[0149] Furthermore, when switching between boost phase-shift control and buck phase-shift control of the dual-active full-bridge converter, the control module can also switch between the second primary-side dual phase-shift mode, State 2, and the second secondary-side dual phase-shift mode, State 6. The phase-shift duty cycle and switching conditions for each mode have been described in detail above and will not be repeated here.

[0150] Furthermore, to achieve the above-mentioned objectives, the present invention further provides an electronic device comprising: a memory, a processor, and a dual-active full-bridge converter control program stored in the memory and executable on the processor, wherein the dual-active full-bridge converter control program is configured to implement the steps of the dual-active full-bridge converter control method described above. Because the dual-active full-bridge converter control program executed on the processor in the electronic device of the present invention is configured to implement the steps of the dual-active full-bridge converter control method described above, the electronic device also has the same advantageous effects as described above and will not be further elaborated upon herein.

[0151] Furthermore, to achieve the above-mentioned objectives, the present invention further provides a storage medium storing a dual-active full-bridge converter control program. When executed by a processor, the dual-active full-bridge converter control program implements the steps of the dual-active full-bridge converter control method described above. Because the storage medium of the present invention stores the dual-active full-bridge converter control program described above, it also has the same beneficial effects as described above and is not further described here.

[0152] In the description of the present invention, “plurality” means two or more, unless otherwise clearly defined.

[0153] The execution order of the steps shown in the flowchart is a preferred implementation mode. In other embodiments of the present invention, the steps may be adjusted according to the functions involved in the steps, for example, they may be executed simultaneously or in the reverse order.

[0154] The logic and / or steps represented in the flowcharts or otherwise described herein, for example, can be considered as a sequenced list of executable instructions for implementing the logical functions, and can be embodied in any computer-readable medium for use by, or in conjunction with, an instruction execution system, apparatus, or device. For purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate, or transport a program for use by, or in conjunction with, an instruction execution system, apparatus, or device.

[0155] Those skilled in the art will understand that all or part of the steps in the method of the above embodiment can be completed by instructing related hardware through a program, and the program can be stored in a computer-readable storage medium. When the program is executed, it includes one or a combination of the steps of the method embodiment.

[0156] In addition, the functional units in the various embodiments of the present invention may be integrated into a single processing module, or each unit may exist physically separately, or two or more units may be integrated into a single module. The aforementioned integrated modules may be implemented in the form of hardware or in the form of software functional modules. If the integrated modules are implemented in the form of software functional modules and sold or used as independent products, they may also be stored in a computer-readable storage medium.

Claims

1. A control method for a dual active full-bridge converter, wherein the dual active full-bridge converter comprises a primary side and a secondary side, characterized in that: The method comprises: S1, determining a phase shift control mode for each working mode when the dual active full-bridge converter performs multiple phase shift control; S2, based on the phase shift control mode of each working mode and the excitation current peak value of the dual active full-bridge converter, calculating the primary side phase shift duty ratio and the secondary side phase shift duty ratio corresponding to each working mode and the switching conditions between different working modes; S3, controlling the dual active full-bridge converter based on the primary side phase-shift duty cycle and the secondary side phase-shift duty cycle corresponding to each of the operating modes and the switching conditions between the different operating modes.

2. The dual active full-bridge converter control method according to claim 1, characterized in that: The excitation current peak value i Lm_max The calculation formula is: Where n is the transformer ratio in the dual active full-bridge converter, V bat is the output voltage, d T is the duty cycle coefficient, and its calculation formula is d T =2-d s +d,d s is the phase shift duty cycle inside the secondary side, d is the phase shift duty cycle outside the original secondary side, L m is the magnetizing inductance, f s is the switching frequency.

3. The dual active full-bridge converter control method according to claim 1, characterized in that: The multiple phase-shift control is a composite multiple phase-shift control including single phase-shift control, double phase-shift control and triple phase-shift control.

4. The dual active full-bridge converter control method according to claim 1, characterized in that: In step S1, the phase shift control mode of each working mode under different voltage control states when the dual active full-bridge converter performs multiple phase shift control is determined, and the voltage control state includes step-down phase shift control and step-up phase shift control.

5. The dual active full-bridge converter control method according to claim 4, characterized in that: When the dual-active full-bridge converter is in step-down phase-shift control, the switchable operating modes include a first triple phase-shift mode, a first primary side double phase-shift mode, a second primary side double phase-shift mode, a third primary side double phase-shift mode, and a single phase-shift mode; when the dual-active full-bridge converter is in step-up phase-shift control, the switchable operating modes include a single phase-shift mode, a first secondary side double phase-shift mode, a second secondary side double phase-shift mode, a third secondary side double phase-shift mode, and a second triple phase-shift mode.

6. The dual active full-bridge converter control method according to claim 5, characterized in that: When the dual active full-bridge converter switches between the boost phase-shift control and the buck phase-shift control, it switches between the second primary-side dual phase-shift mode and the second secondary-side dual phase-shift mode.

7. The dual active full-bridge converter control method according to claim 1, characterized in that: Step S3 specifically includes: According to the current operating mode of the dual-active full-bridge converter and the primary-secondary side external phase shift duty cycle, based on the switching conditions between the different operating modes, the next operating mode of the dual-active full-bridge converter is obtained; The dual active full-bridge converter is controlled based on the primary side inner phase shift angle and the secondary side inner phase shift angle corresponding to the next working mode.

8. A dual active full-bridge converter control system, wherein the dual active full-bridge converter comprises a primary side and a secondary side, characterized in that: include: A mode determination module, the mode determination module is used to determine the phase shift control mode of each working mode when the dual active full-bridge converter performs multiple phase shift control; a calculation module, wherein the calculation module calculates the phase-shift duty ratio within the primary side and the phase-shift duty ratio within the secondary side corresponding to each working mode and the switching conditions between different working modes based on the phase-shift control mode of each working mode and the excitation current peak value of the dual-active full-bridge converter; A control module controls the dual active full-bridge converter based on the phase-shifted duty cycle in the primary side and the phase-shifted duty cycle in the secondary side corresponding to each of the working modes and the switching conditions between the different working modes.

9. An electronic device comprising a memory, a processor, and a dual active full-bridge converter control program stored in the memory and executable on the processor, wherein: When the processor executes the dual active full-bridge converter control program, the dual active full-bridge converter control method according to any one of claims 1 to 7 is implemented.

10. A storage medium storing a dual active full-bridge converter control program, characterized in that: When the computer program is executed by a processor, the dual active full-bridge converter control program according to any one of claims 1 to 7 is implemented.

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