Resonant isolated active bridge converter control method, system, device and medium

Abstract

The invention provides a control method, system and device of a resonance-based isolated active bridge converter and a medium. The system comprises a primary side circuit module, an L-C series resonant cavity, a high-frequency transformer and a secondary side circuit module. The method comprises the following steps of: sampling primary and secondary voltage and current, calculating voltage gain, and solving threshold current of primary and secondary switching tubes for realizing zero voltage switching (ZVS) in combination with junction capacitance and dead time; geometric constraints of resonance current and capacitor voltage are established based on phase plane analysis, the proportions of a primary side inner phase shift angle, a secondary side inner phase shift angle and an outer phase shift angle relative to a resonance period are solved in a unified mode, and then the switching frequency is determined; and converting to obtain an actual phase shift angle and generating a gate pole driving signal, thereby realizing full-working-condition ZVS of the primary and secondary side devices. The soft switching boundary is accurately given in the wide voltage gain and wide load range, the peak value and the effective value of the resonance current are remarkably reduced, the conduction and switching loss are considered, the circulation is suppressed, and the efficiency and the power density are improved.

Description

Control methods, systems, equipment, and media for resonant isolated active bridge converters Technical Field

[0001] This invention relates to the field of power converter technology, and more specifically, to a control method, system, device, and medium for a resonant isolated active bridge converter. Background Technology

[0002] Isolated active bridge (DAB) converters are widely used in photovoltaic-storage DC buses and battery energy storage, vehicle charging and discharging, data center backup power supplies, and high-reliability industrial power supplies due to their advantages such as high efficiency, high power density, ease of electrical isolation, and bidirectional energy flow. Traditional dual active bridge topologies mainly rely on the series equivalent inductance and phase shift of the primary and secondary side square wave voltages to achieve power transfer. The control approach is clear, but the current exhibits a linear ramp, with relatively large peak and RMS values, resulting in high conduction and switching losses. Furthermore, under wide voltage gain and wide load ranges, some devices struggle to maintain zero-voltage turn-on (ZVS).

[0003] To reduce losses, resonant isolated active bridges introduce an LC series resonant cavity between the high-frequency transformer and the bridge arm, making the resonant current dominant in the commutation range, thereby expanding the soft-switching range and reducing switching and conduction losses. However, existing resonant control methods mostly use fundamental equivalent or simplified average models, usually only providing power regulation laws based on a single phase shift or frequency conversion, making it difficult to simultaneously solve for the geometric relationship between the inner and outer phase shifts of the primary and secondary sides and the resonant period. In addition, existing methods do not adequately consider the combined effects of switch junction capacitance, dead time, and voltage gain, making it difficult to accurately give the threshold current and corresponding phase shift and frequency configuration required for each switch to achieve ZVS in the dead zone under different operating conditions. This leads to inaccurate prediction of soft-switching boundaries, and some devices lose ZVS under specific operating conditions. It is difficult to balance transmission power and soft-switching constraints, limiting system efficiency and thermal design. The high coupling between power and phase shift makes engineering tuning complex, and circulating current and additional losses are easily generated in the dynamic process. Therefore, there is an urgent need for a method that can simultaneously consider the relationship between the primary and secondary voltages, the effects of junction capacitance and dead time, and can uniformly solve the primary side inward phase shift angle, the secondary side inward phase shift angle, the outward phase shift angle and the switching frequency in the phase plane, so as to realize a resonant isolated active bridge control strategy with high efficiency and full device ZVS throughout the entire operating region.

[0004] Patent application CN113037097A discloses a modulation control method for a resonant dual active bridge converter, comprising: First, in the resonant dual active bridge converter, Vin and Vo are the input voltage and output voltage of the resonant dual active bridge converter, respectively; it and io are the resonant current and output current of the resonant dual active bridge converter, respectively; Co is the output filter capacitor of the resonant dual active bridge converter; Lt and Ct are the resonant inductance and resonant capacitance of the resonant dual active bridge converter, respectively; switching devices M1 to M4 are four switching devices on the primary side of the resonant dual active bridge converter; switching devices M5 to M8 are four switching devices on the secondary side of the resonant dual active bridge converter; these eight switching devices each correspond to an anti-parallel diode dM1 to dM8 and a parasitic capacitor CM1 to CM8; n is the transformer turns ratio of the resonant dual active bridge converter; then, adjusting the gate trigger signal of each switching device M1 to M8, a high-frequency pulse width modulation mode is obtained, thereby generating a primary AC voltage υAB and a secondary AC voltage υCD. However, this patent cannot completely solve the existing technical problems, nor can it meet the needs of this invention. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a control method, system, device, and medium for a resonant isolated active bridge converter.

[0006] According to the control method of the resonant isolated active bridge converter provided by the present invention, the resonant isolated active bridge converter includes a primary circuit module, an LC series resonant cavity, a high-frequency transformer, and a secondary circuit module;

[0007] The primary circuit module is connected to the primary winding of the high-frequency transformer to modulate the DC input into a high-frequency AC voltage. The secondary circuit module is connected to the secondary winding of the high-frequency transformer through the LC series resonant cavity to rectify or transmit the AC voltage. The high-frequency transformer is connected between the primary and secondary circuit modules to achieve electrical isolation and voltage level matching between the primary and secondary sides. The LC series resonant cavity includes a resonant capacitor and a resonant inductor, which are connected in series in the AC circuit formed by the secondary winding of the high-frequency transformer and the secondary circuit module to control the current waveform using the resonance effect to assist the switching transistor in achieving zero-voltage turn-on. The control method includes the following steps: Step 1: Obtain the primary voltage and current, and the secondary voltage and current; Step 2: Calculate the primary and secondary voltage gains based on the relationship between the primary and secondary voltages, and determine... Step 3: Determine the threshold current for zero-voltage turn-on soft switching of the primary and secondary switching transistors using phase plane analysis, based on the voltage gain and soft-switching threshold current. Step 4: Determine the switching frequency based on the ratio of the primary-side inward phase shift angle, secondary-side inward phase shift angle, and external phase shift angle relative to the resonant period, and the geometric relationship obtained from the phase plane. Step 5: Determine the actual primary-side inward phase shift angle, secondary-side inward phase shift angle, and external phase shift angle based on the switching frequency and the ratio of the primary and secondary-side inward and external phase shift angles relative to the resonant period. Step 6: Generate a control gate drive signal based on the primary-side inward phase shift angle, secondary-side inward phase shift angle, external phase shift angle, and switching frequency to control the turn-on and turn-off of the primary and secondary switching transistors. The soft-switching threshold current of the primary switching transistor is... Positively correlated with primary-side voltage and primary-side switch junction capacitance, and negatively correlated with dead time; secondary-side switch soft-switching threshold current. It is positively correlated with the secondary side voltage and the junction capacitance of the secondary side switch, and negatively correlated with the dead time.

[0008] Preferably, when the voltage gain When the value is less than 1, if the inner phase shift is not zero, the ratio of the inner and outer phase shift angles of the primary and secondary sides to the resonant period is:

[0009] in, For the impedance of the resonant network, This represents the peak value of the resonant capacitor voltage. This is the secondary voltage. This is the voltage referred from the primary side to the secondary side of the transformer; This represents the first part of the central angle corresponding to the arc of the trajectory in the phase plane of the third operating mode. This angle is related to the threshold current required for the primary-side switch to achieve ZVS. related; This represents the second part of the central angle corresponding to the arc of the trajectory in the phase plane of the third operating mode. This angle is related to the threshold current required for the secondary-side switch to achieve ZVS. related; This represents the first part of the central angle corresponding to the arc of the trajectory in the phase plane of the first working mode; This represents the second part of the central angle corresponding to the arc of the trajectory in the phase plane of the first operating mode. This angle is related to the threshold current required for the secondary-side switch to achieve ZVS. related; This represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the first working mode within one switching cycle; This represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the second working mode within one switching cycle; It represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the third working mode within one switching cycle; Represents the radius of the circle representing the phase plane trajectory of the first working mode; Represents the radius of the circle representing the phase plane trajectory of the third working mode; This represents the radius of the phase plane trajectory circle of the second working mode.

[0010] Preferably, when the voltage gain When the value is greater than 1, if the inner phase shift is not zero, the ratio of the inner and outer phase shift angles of the primary and secondary sides to the resonant period is:

[0011] in, For the impedance of the resonant network, This represents the peak value of the resonant capacitor voltage. This is the secondary voltage. This is the voltage referred from the primary side to the secondary side of the transformer; This represents the first part of the central angle corresponding to the arc of the trajectory in the phase plane of the third operating mode. This angle is related to the threshold current required for the primary-side switch to achieve ZVS. related; This represents the second part of the central angle corresponding to the arc of the trajectory in the phase plane of the third operating mode. This angle is related to the threshold current required for the secondary-side switch to achieve ZVS. related; This represents the first part of the central angle corresponding to the arc of the trajectory in the phase plane of the first working mode; This represents the second part of the central angle corresponding to the arc of the trajectory in the phase plane of the first operating mode. This angle is related to the threshold current required for the secondary-side switch to achieve ZVS. related; This represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the first working mode within one switching cycle; This represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the second working mode within one switching cycle; It represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the third working mode within one switching cycle; Represents the radius of the circle representing the phase plane trajectory of the first working mode; Represents the radius of the circle representing the phase plane trajectory of the third working mode; This represents the radius of the phase plane trajectory circle of the second working mode.

[0012] Preferably, when the voltage gain When the value is less than 1, if the inner phase shift angle is 0, the ratio of the inner and outer phase shift angles of the primary and secondary sides to the resonant period is:

[0013] in, This represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the first working mode within one switching cycle; This represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the second working mode within one switching cycle; It represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the third working mode within one switching cycle; Represents the radius of the circle representing the phase plane trajectory of the first working mode; Represents the radius of the circle representing the phase plane trajectory of the third working mode; This is the secondary current; Indicates the switching frequency of the converter; Indicates the value of the resonant capacitor; This is the secondary voltage; This is the voltage referred from the primary side to the secondary side of the transformer; This refers to the current converted from the primary side to the secondary side of the transformer. This is the impedance of the resonant network.

[0014] Preferably, when the voltage gain When the value is greater than 1, if the inner phase shift angle is 0, the ratio of the inner and outer phase shift angles of the primary and secondary sides to the resonant period is:

[0015] in, This represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the first working mode within one switching cycle; This represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the second working mode within one switching cycle; It represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the third working mode within one switching cycle; Represents the radius of the circle representing the phase plane trajectory of the first working mode; Represents the radius of the circle representing the phase plane trajectory of the third working mode; This is the secondary current; Indicates the switching frequency of the converter; Indicates the value of the resonant capacitor; This is the secondary voltage; This is the voltage referred from the primary side to the secondary side of the transformer; This refers to the current converted from the primary side to the secondary side of the transformer. This is the impedance of the resonant network.

[0016] Preferably, the formula for calculating the switching frequency is:

[0017] in, Indicates the switching frequency of the converter; This represents the inherent resonant frequency of the resonant cavity; This represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the first working mode within one switching cycle; This represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the second working mode within one switching cycle; It represents the center angle of the circular arc corresponding to the trajectory in the phase plane of the third working mode within one switching cycle.

[0018] Preferably, the formulas for calculating the actual primary side inward phase shift angle, secondary side inward phase shift angle, and outer phase shift angle are:

[0019]

[0020] in, For voltage gain, The phase angle is the inward shift of the original side. The phase angle is the inward shift of the secondary side. This is the outward phase angle; This represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the first working mode within one switching cycle; This represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the second working mode within one switching cycle; It represents the center angle of the circular arc corresponding to the trajectory in the phase plane of the third working mode within one switching cycle.

[0021] The control system for a resonant isolated active bridge converter according to the present invention includes: a sampling module for acquiring primary-side voltage and current, and secondary-side voltage and current; a first calculation module for determining the threshold current for the primary-side and secondary-side switches to achieve zero-voltage turn-on soft switching based on the relationship between the primary and secondary-side voltages; a second calculation module for calculating the primary and secondary-side voltage gains based on the relationship between the primary and secondary-side voltages, and determining the threshold current for the primary-side and secondary-side switches to achieve zero-voltage turn-on soft switching; and a third calculation module for calculating the voltage gain based on the voltage gain... The Yihe soft-switching threshold current is determined using phase plane analysis to determine the proportions of the primary-side inner phase shift angle, the secondary-side inner phase shift angle, and the outer phase shift angle relative to the resonant period, thereby determining the switching frequency. The fourth calculation module is used to determine the actual primary-side inner phase shift angle, the secondary-side inner phase shift angle, and the outer phase shift angle based on the switching frequency and the proportions of the primary and secondary-side inner and outer phase shift angles relative to the resonant period. The drive signal generation module is used to generate a control gate drive signal based on the inner phase shift angle, the outer phase shift angle, and the switching frequency to control the turn-on and turn-off of the primary-side and secondary-side switches.

[0022] The computer device provided by the present invention includes: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions, wherein the computer-executable instructions, when executed by the processor, implement the steps of the control method for the resonant isolated active bridge converter.

[0023] According to the computer-readable storage medium provided by the present invention, it stores computer-executable instructions, which, when executed by a processor, implement the steps of the control method for the resonant isolated active bridge converter.

[0024] Compared with the prior art, the present invention has the following beneficial effects: (1) Under different voltage gain and load range and different internal phase shift configurations, the present invention can solve the switching strategy by means of phase plane geometric constraints and threshold current model, which can simultaneously guarantee the ZVS of the primary and secondary side switches and realize soft turn-on in the whole working area; (2) While satisfying ZVS, the peak value and effective value of resonant current are reduced by jointly solving the ratio of internal / external phase shift angle and switching frequency, which significantly reduces the copper loss of inductor and the conduction loss of device; (3) The method of the present invention only relies on conventional voltage and current sampling, and can output gate drive by cooperating with digital controller to calculate phase shift and frequency in real time. No additional sensors or complex predictors are required, and it is easy to implement on DSP / MCU / FPGA. Attached Figure Description

[0025] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 is a schematic flowchart of the overall process of a control method for a resonant isolated active bridge converter based on switching current control according to an embodiment of the present invention.

[0026] Figures 2a and 2b are schematic diagrams of the topology and equivalent model of a resonant isolated active bridge converter provided in an embodiment of the present invention; Figures 3a, 3b, and 3c are schematic diagrams of three structures of a resonant isolated active bridge DC converter provided in an embodiment of the present invention; Figures 4a, 4b, and 4c are schematic diagrams of three structures of a resonant isolated active bridge AC converter provided in an embodiment of the present invention; Figure 5 is a schematic diagram of the phase plane relationship between resonant voltage and resonant current when the voltage gain M is less than 1 in an embodiment of the present invention; Figure 6 is a schematic diagram of the phase plane relationship between resonant voltage and resonant current when the voltage gain M is greater than 1 in an embodiment of the present invention; Figure 7 is a schematic diagram of the phase plane relationship between resonant voltage and resonant current when the inner phase shift angle is equal to 0 in an embodiment of the present invention; Figure 8 is a schematic diagram of the controller of a resonant isolated active bridge converter in an embodiment of the present invention. Detailed Implementation

[0027] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0028] Example 1, referring to Figures 1-4, is an embodiment of the present invention, providing a control method for a resonant isolated active bridge converter. As shown in Figure 1, it includes: S100: Sampling to obtain the primary-side voltage and current, and the secondary-side voltage and current; combining the turns ratio to equate the primary and secondary sides to a unified side for subsequent calculations; S200: Calculating the threshold current required for the primary and secondary side switches to achieve ZVS based on the primary-secondary voltage relationship and dead time; S300: Segmented solution in the phase plane, using the ZVS threshold current of the primary and secondary side switches as boundary conditions, constructing segmented arc trajectories on the phase plane to obtain the primary-side inward phase shift angle and the secondary-side inward phase shift angle. S400: Switching frequency calculation: Based on the phase plane geometry and power constraints, calculate the switching frequency; S500: Actual phase shift angle calculation: Convert the actual primary side inner phase shift angle, secondary side inner phase shift angle, and outer phase shift angle from the phase shift angle ratio and the switching frequency; S600: Gate drive generation: Based on the primary side inner phase shift angle, secondary side inner phase shift angle, and outer phase shift angle and the switching frequency, synthesize the primary and secondary side gate drives to control the turn-on and turn-off of each switch.

[0029] This method employs phase-shift frequency modulation to control the primary and secondary units of a resonant isolated active bridge converter. The basic topology of the resonant isolated active bridge converter, as shown in Figure 2a, includes a primary power conversion unit, a high-frequency resonant cavity unit, and a secondary power conversion unit. The primary power conversion unit is a full-bridge or half-bridge structure composed of controllable switches. The secondary power conversion unit is also a full-bridge or half-bridge structure composed of controllable switches. The high-frequency resonant cavity unit includes a primary winding, a secondary winding, a resonant inductor, and a resonant capacitor. The primary winding is connected to the primary power conversion unit, and the secondary winding is connected to the secondary power conversion unit via the resonant inductor and capacitor. Figure 2b shows the equivalent circuit diagram of the primary and secondary voltages and the resonant cavity during the switching cycle. The primary voltage is a three-level square wave voltage, and the secondary voltage is a two-level square wave voltage. The primary and secondary voltages charge and discharge the LC resonant cavity to regulate the transmitted power. Adjusting the switching frequency and the internal and external phase shift angles of the primary and secondary voltages can control the magnitude of the transmitted power.

[0030] In practical DC-DC conversion applications, bidirectional switching transistors are used on the AC side to block AC voltage. A resonant isolated active bridge converter with the structure shown in Figure 2a can have a circuit topology of a full-bridge-full-bridge structure as shown in Figure 3a, or a full-bridge-half-bridge or half-bridge-half-bridge structure as shown in Figures 3b and 3c. In the half-bridge structure, the half-bridge capacitor can act as a resonant capacitor, thus the converter can also eliminate the series resonant capacitor and use a split resonant capacitor structure. In practical DC-AC conversion applications, a resonant isolated active bridge converter with the structure shown in Figure 2a can have a circuit topology of a full-bridge-full-bridge structure as shown in Figure 4a, or a full-bridge-half-bridge or half-bridge-half-bridge structure as shown in Figures 4b and 4c. In the half-bridge structure, the half-bridge capacitor can act as a resonant capacitor, thus the converter can also eliminate the series resonant capacitor and use a split resonant capacitor structure. Example 2, referring to Figures 1-8, is an embodiment of the present invention. Based on the above embodiments, a control method for a resonant isolated active bridge converter is provided.

[0031] In this embodiment of the application, the primary side voltage and current and the secondary side voltage and current are obtained in step S100; the primary and secondary sides are equivalent to the same side in combination with the turns ratio for subsequent calculations. In order to unify the dimensions and facilitate analysis, all variables involved thereafter are considered to be equivalent to the same side for analysis unless explicitly stated.

[0032] In this embodiment, in step S200, to achieve zero-voltage soft switching, during the dead time, the inductor current resonates with the junction capacitance of the switching transistor. The current discharges the junction capacitance of the switching transistor, causing its voltage to naturally resonate to zero. Afterwards, turning on the corresponding switching transistor achieves zero-voltage switching. Therefore, the inductor current needs to meet certain direction and magnitude conditions, namely: the threshold current for the primary-side switching transistor to achieve zero-voltage soft switching is... The threshold current for the secondary-side switch to achieve zero-voltage turn-on soft switching is... Based on the primary and secondary voltage relationships, determine the threshold currents for zero-voltage turn-on soft switching of the primary and secondary switches, including: the soft-switching threshold current of the primary switch. It is positively correlated with the primary-side voltage and the primary-side switch junction capacitance, and negatively correlated with the dead time. In certain special cases... The given value can be zero; the soft-switching threshold current of the secondary switch. It is positively correlated with the secondary-side voltage and the junction capacitance of the secondary-side switch, and negatively correlated with the dead time. In some special cases... The given value can be zero.

[0033] In this embodiment of the application, the phase plane solution method in step S300 specifically provides the time-domain general solution for the resonant current and resonant voltage as follows:

[0034] in, This is the resonant inductor current; This is the voltage of the resonant capacitor; It is the resonant angular frequency. ; This is the primary voltage of the resonant cavity; This is the secondary side voltage of the resonant cavity; and These represent the current value of the resonant inductor and the voltage value of the resonant capacitor at the initial moment of this interval; This represents the instantaneous time in the current switching mode; The natural resonant frequency of the LC resonant cavity is represented by... Sure, Indicates the value of the resonant inductance. Indicates the value of the resonant capacitor; The resonant network impedance; the resonant current and resonant voltage satisfy the following relationship:

[0035] in, The radius of the arc of the k-th switching mode in the phase plane trajectory is determined by the initial state and equivalent voltage of the mode.

[0036] Therefore, the resonant current and resonant voltage change according to a certain circular trajectory, the center of which is determined by the primary voltage of the resonant cavity. and secondary voltage The radius is determined by the initial conditions.

[0037] In this embodiment, step S300 uses the ZVS threshold current achieved by the primary and secondary side switches as the boundary condition, constructs a segmented circular arc trajectory on the phase plane, and calculates the proportions of the primary side inward phase shift angle, the secondary side inward phase shift angle, and the outward phase shift angle relative to the resonant period. This includes a case where the voltage gain... When the value is less than 1, if the inner phase shift is not zero, the ratio of the inner and outer phase shift angles of the primary and secondary sides to the resonant period is:

[0038] in, For the impedance of the resonant network, , This represents the peak value of the resonant capacitor voltage. This is the secondary voltage. This is the voltage referred from the primary side to the secondary side of the transformer. , , The radius of the trajectory circle at each stage in the phase plane trajectory diagram; This represents the first part of the central angle corresponding to the arc of the trajectory in the phase plane of the third operating mode. This angle is related to the threshold current required for the primary-side switch to achieve ZVS. related; This represents the second part of the central angle corresponding to the arc of the trajectory in the phase plane of the third operating mode. This angle is related to the threshold current required for the secondary-side switch to achieve ZVS. related; This represents the first part of the central angle corresponding to the arc of the trajectory in the phase plane of the first working mode; This represents the second part of the central angle corresponding to the arc of the trajectory in the phase plane of the first operating mode. This angle is related to the threshold current required for the secondary-side switch to achieve ZVS. related; This represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the first working mode within one switching cycle; This represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the second working mode within one switching cycle; It represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the third working mode within one switching cycle; Indicates the switching frequency of the converter; Indicates the value of the resonant inductance; Indicates the value of the resonant capacitor; Represents the radius of the circle representing the phase plane trajectory of the first working mode; Represents the radius of the circle representing the phase plane trajectory of the third working mode; This represents the radius of the circle tracing the phase plane trajectory of the second operating mode; according to the soft-switching constraint, and The following relationship must be satisfied:

[0039] in, This represents the instantaneous resonant current value at state point F (corresponding to the moment the secondary switch operates) in the phase plane trajectory; This represents the instantaneous resonant current value at state point E (corresponding to the moment the primary side lagging arm switch operates) in the phase plane trajectory; specifically, the schematic diagram of the phase plane relationship between the resonant voltage and resonant current is shown in Figure 5. In some cases, Given value or The given value can be zero.

[0040] In this embodiment of the application, step S300 also includes another case, when the voltage gain When the value is greater than 1, if the inner phase shift is not zero, the ratio of the inner and outer phase shift angles of the primary and secondary sides to the resonant period is:

[0041] in, For the impedance of the resonant network, , This represents the peak value of the resonant capacitor voltage. This is the secondary voltage. This is the voltage referred from the primary side to the secondary side of the transformer. , , Let be the radius of the trajectory circle at each stage in the phase plane trajectory diagram.

[0042] According to the soft-switching constraint conditions and The following relationship must be satisfied:

[0043] in, This represents the instantaneous resonant current value at state point E (corresponding to the moment the secondary lead arm switch operates) in the phase plane trajectory. This represents the instantaneous resonant current value at state point D (corresponding to the moment the primary-side switch operates) in the phase plane trajectory; specifically, the schematic diagram of the phase plane relationship between the resonant voltage and resonant current is shown in Figure 6. In some cases, Given value or The given value can be zero.

[0044] In this embodiment of the application, step S300 also includes another case, when the voltage gain When the value is less than 1, if the inner phase shift angle is 0, the ratio of the inner and outer phase shift angles of the primary and secondary sides to the resonant period is:

[0045] in, For the impedance of the resonant network, , This represents the peak value of the resonant capacitor voltage. This is the secondary voltage. For secondary current, This is the voltage referred from the primary side to the secondary side of the transformer. This refers to the current converted from the primary side to the secondary side of the transformer. , Let be the radius of the trajectory circle at each stage in the phase plane trajectory diagram.

[0046] According to the soft-switching constraint conditions The following relationship must be satisfied:

[0047] Specifically, the schematic diagram of the phase plane relationship between the resonant voltage and resonant current is shown in Figure 7. In some cases, The given value can be zero.

[0048] In this embodiment of the application, step S300 also includes another case, when the voltage gain When the value is greater than 1, if the inner phase shift angle is 0, the ratio of the inner and outer phase shift angles of the primary and secondary sides to the resonant period is:

[0049] in, For the impedance of the resonant network, , This represents the peak value of the resonant capacitor voltage. This is the secondary voltage. For secondary current, This is the voltage referred from the primary side to the secondary side of the transformer. This refers to the current converted from the primary side to the secondary side of the transformer. , Let be the radius of the trajectory circle at each stage in the phase plane trajectory diagram.

[0050] According to the soft-switching constraint conditions The following relationship exists:

[0051] in, This represents the instantaneous resonant current value at state point E (corresponding to the moment the primary-side switch operates) in the phase plane trajectory; specifically, the schematic diagram of the phase plane relationship between the resonant voltage and resonant current is shown in Figure 7. In some cases, The given value can be zero.

[0052] In this embodiment of the application, step S400 involves solving for the switching frequency. Based on the phase plane geometry and power constraints, the switching frequency is calculated using the following formula:

[0053] in, The natural resonant frequency of the resonant cavity is represented by... Determined; In this embodiment of the application, step S500 involves calculating the actual phase shift angle. The actual primary side inner phase shift angle, secondary side inner phase shift angle, and outer phase shift angle are calculated from the phase shift angle ratio and the switching frequency. The formulas for calculating the actual primary side inner phase shift angle, secondary side inner phase shift angle, and outer phase shift angle are as follows:

[0054]

[0055] in, The phase angle is the inward shift of the original side. The phase angle is the inward shift of the secondary side. This is the outward phase angle.

[0056] In the embodiments of this application, step S600, gate drive generation, is performed by synthesizing the primary and secondary gate drives based on the primary side inner phase shift angle, the secondary side inner phase shift angle and the outer phase shift angle and the switching frequency, thereby controlling the turn-on and turn-off of each switch.

[0057] It should be noted that in the above embodiments, the phase plane geometric constraints and threshold current model are used to solve the switching strategy in a unified manner, which can simultaneously guarantee the ZVS of the primary and secondary switches, and achieve soft turn-on across the entire operating region. While satisfying ZVS, the peak and effective values ​​of the resonant current are reduced by jointly solving the ratio of the inner / outer phase shift and the switching frequency, significantly reducing inductor copper loss and device conduction loss.

[0058] Example 3 illustrates a schematic scheme for a resonant isolated active bridge converter controller. It should be noted that the technical solution of this isolated resonant active bridge converter controller system belongs to the same concept as the control method for the resonant isolated active bridge converter described above. Details not described in detail in this embodiment can be found in the description of the control method for the resonant isolated active bridge converter described above.

[0059] As shown in Figure 8, this embodiment also provides another control system for a resonant isolated active bridge converter, including: a sampling module for acquiring primary-side voltage and current, and secondary-side voltage and current; a first calculation module for determining the threshold current for the primary-side and secondary-side switches to achieve zero-voltage turn-on soft switching based on the relationship between the primary and secondary-side voltages; a second calculation module for calculating the primary and secondary-side voltage gains based on the relationship between the primary and secondary-side voltages, and determining the threshold current for the primary-side and secondary-side switches to achieve zero-voltage turn-on soft switching; and a third calculation module for... The voltage gain and soft-switching threshold current are used to determine the proportions of the primary-side inner phase shift angle, the secondary-side inner phase shift angle, and the outer phase shift angle relative to the resonant period using phase plane analysis, thereby determining the switching frequency. A fourth calculation module is used to determine the actual primary-side inner phase shift angle, secondary-side inner phase shift angle, and outer phase shift angle based on the switching frequency and the proportions of the primary and secondary-side inner and outer phase shift angles relative to the resonant period. A drive signal generation module is used to generate a control gate drive signal based on the inner phase shift angle, outer phase shift angle, and switching frequency to control the turn-on and turn-off of the primary and secondary-side switches.

[0060] It should be noted that the first calculation module, the second calculation module, the third calculation module, and the fourth calculation module belong to the control parameter calculation module.

[0061] This embodiment also provides a computer device applicable to power modulation of a resonant isolated active bridge converter, comprising: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to implement the power modulation method for the resonant isolated active bridge converter proposed in the above embodiment.

[0062] This embodiment also provides a storage medium storing a computer program that, when executed by a processor, implements the power modulation method for implementing a resonant isolated active bridge converter as proposed in the above embodiments.

[0063] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A control method for a resonant isolated active bridge converter, characterized in that, The resonant isolated active bridge converter includes a primary circuit module, an LC series resonant cavity, a high-frequency transformer, and a secondary circuit module. The primary circuit module is connected to the primary winding of the high-frequency transformer to modulate the DC input into a high-frequency AC voltage. The secondary circuit module is connected to the secondary winding of the high-frequency transformer through the LC series resonant cavity to rectify or transmit the AC voltage. The high-frequency transformer is connected between the primary and secondary circuit modules to achieve electrical isolation and voltage level matching between the primary and secondary sides. The LC series resonant cavity includes a resonant capacitor and a resonant inductor, which are connected in series in the AC circuit formed by the secondary winding of the high-frequency transformer and the secondary circuit module to control the current waveform using the resonance effect to assist the switching transistor in achieving zero-voltage turn-on. The control method includes the following steps: Step 1: Obtain the primary voltage and current, and the secondary voltage and current; Step 2: According to... Step 3: Based on the voltage gain and soft-switching threshold current, determine the proportions of the primary-side inward phase shift angle, the secondary-side inward phase shift angle, and the outward phase shift angle relative to the resonant period using phase plane analysis. Step 4: Based on the proportions of the primary-side inward phase shift angle, the secondary-side inward phase shift angle, and the outward phase shift angle relative to the resonant period, and the geometric relationship obtained from the phase plane, determine the switching frequency. Step 5: Based on the switching frequency and the proportions of the primary-side inward phase shift angle and the outward phase shift angle relative to the resonant period, determine the actual primary-side inward phase shift angle, the secondary-side inward phase shift angle, and the outward phase shift angle. Step 6: Based on the primary-side inward phase shift angle, the secondary-side inward phase shift angle, the outward phase shift angle, and the switching frequency, generate a control gate drive signal to control the turn-on and turn-off of the primary-side and secondary-side switches. The soft-switching threshold current of the primary-side switch is... Positively correlated with primary-side voltage and primary-side switch junction capacitance, and negatively correlated with dead time; secondary-side switch soft-switching threshold current. It is positively correlated with the secondary side voltage and the junction capacitance of the secondary side switch, and negatively correlated with the dead time.

2. The control method for the resonant isolated active bridge converter according to claim 1, characterized in that, When voltage gain When the value is less than 1, if the inner phase shift is not zero, the ratio of the inner and outer phase shift angles of the primary and secondary sides to the resonant period is: in, For the resonant network impedance, This represents the peak value of the resonant capacitor voltage. This is the secondary voltage. This is the voltage referred from the primary side to the secondary side of the transformer; This represents the first part of the central angle corresponding to the arc of the trajectory in the phase plane of the third operating mode. This angle is related to the threshold current required for the primary-side switch to achieve ZVS. related; This represents the second part of the central angle corresponding to the arc of the trajectory in the phase plane of the third operating mode. This angle is related to the threshold current required for the secondary-side switch to achieve ZVS. related; This represents the first part of the central angle corresponding to the arc of the trajectory in the phase plane of the first working mode; This represents the second part of the central angle corresponding to the arc of the trajectory in the phase plane of the first operating mode. This angle is related to the threshold current required for the secondary-side switch to achieve ZVS. related; This represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the first working mode within one switching cycle; This represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the second working mode within one switching cycle; It represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the third working mode within one switching cycle; Represents the radius of the circle representing the phase plane trajectory of the first working mode; Represents the radius of the circle representing the phase plane trajectory of the third working mode; This represents the radius of the phase plane trajectory circle of the second working mode.

3. The control method for the resonant isolated active bridge converter according to claim 1, characterized in that, When voltage gain When the value is greater than 1, if the inner phase shift is not zero, the ratio of the inner and outer phase shift angles of the primary and secondary sides to the resonant period is: in, For the resonant network impedance, This represents the peak value of the resonant capacitor voltage. This is the secondary voltage. This is the voltage referred from the primary side to the secondary side of the transformer; This represents the first part of the central angle corresponding to the arc of the trajectory in the phase plane of the third operating mode. This angle is related to the threshold current required for the primary-side switch to achieve ZVS. related; This represents the second part of the central angle corresponding to the arc of the trajectory in the phase plane of the third operating mode. This angle is related to the threshold current required for the secondary-side switch to achieve ZVS. related; This represents the first part of the central angle corresponding to the arc of the trajectory in the phase plane of the first working mode; This represents the second part of the central angle corresponding to the arc of the trajectory in the phase plane of the first operating mode. This angle is related to the threshold current required for the secondary-side switch to achieve ZVS. related; This represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the first working mode within one switching cycle; This represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the second working mode within one switching cycle; It represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the third working mode within one switching cycle; Represents the radius of the circle representing the phase plane trajectory of the first working mode; Represents the radius of the circle representing the phase plane trajectory of the third working mode; This represents the radius of the phase plane trajectory circle of the second working mode.

4. The control method for the resonant isolated active bridge converter according to claim 1, characterized in that, When voltage gain When the value is less than 1, if the inner phase shift angle is 0, the ratio of the inner and outer phase shift angles of the primary and secondary sides to the resonant period is: in, This represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the first working mode within one switching cycle; This represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the second working mode within one switching cycle; It represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the third working mode within one switching cycle; Represents the radius of the circle representing the phase plane trajectory of the first working mode; Represents the radius of the circle representing the phase plane trajectory of the third working mode; This is the secondary current; Indicates the switching frequency of the converter; Indicates the value of the resonant capacitor; This is the secondary voltage; This is the voltage referred from the primary side to the secondary side of the transformer; This refers to the current converted from the primary side to the secondary side of the transformer. This is the impedance of the resonant network.

5. The control method for the resonant isolated active bridge converter according to claim 1, characterized in that, When voltage gain When the value is greater than 1, if the inner phase shift angle is 0, the ratio of the inner and outer phase shift angles of the primary and secondary sides to the resonant period is: in, This represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the first working mode within one switching cycle; This represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the second working mode within one switching cycle; It represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the third working mode within one switching cycle; Represents the radius of the circle representing the phase plane trajectory of the first working mode; Represents the radius of the circle representing the phase plane trajectory of the third working mode; This is the secondary current; Indicates the switching frequency of the converter; Indicates the value of the resonant capacitor; This is the secondary voltage; This is the voltage referred from the primary side to the secondary side of the transformer; This refers to the current converted from the primary side to the secondary side of the transformer. This is the impedance of the resonant network.

6. The control method for the resonant isolated active bridge converter according to claim 1, characterized in that, The formula for calculating the switching frequency is: in, Indicates the switching frequency of the converter; This represents the inherent resonant frequency of the resonant cavity; This represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the first working mode within one switching cycle; This represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the second working mode within one switching cycle; It represents the center angle of the circular arc corresponding to the trajectory in the phase plane of the third working mode within one switching cycle.

7. The control method for the resonant isolated active bridge converter according to claim 1, characterized in that, The formulas for calculating the actual phase shift angles of the primary side, secondary side, and external side are as follows: in, For voltage gain, The phase angle is the inward shift of the original side. The phase angle is the inward shift of the secondary side. This is the outward phase angle; This represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the first working mode within one switching cycle; This represents the center angle of the circular arc corresponding to the trajectory arc in the phase plane of the second working mode within one switching cycle; It represents the center angle of the circular arc corresponding to the trajectory in the phase plane of the third working mode within one switching cycle.

8. A control system for a resonant isolated active bridge converter, characterized in that, The control method for a resonant isolated active bridge converter as described in any one of claims 1 to 7 includes: a sampling module for acquiring primary-side voltage and current, and secondary-side voltage and current; a first calculation module for determining the threshold current for zero-voltage turn-on soft switching of the primary-side and secondary-side switches based on the relationship between the primary and secondary-side voltages; a second calculation module for calculating the primary and secondary-side voltage gains based on the relationship between the primary and secondary-side voltages, and determining the threshold current for zero-voltage turn-on soft switching of the primary and secondary-side switches; and a third calculation module for... The voltage gain and soft-switching threshold current are used to determine the proportions of the primary-side inner phase shift angle, the secondary-side inner phase shift angle, and the outer phase shift angle relative to the resonant period using phase plane analysis, thereby determining the switching frequency. A fourth calculation module is used to determine the actual primary-side inner phase shift angle, secondary-side inner phase shift angle, and outer phase shift angle based on the switching frequency and the proportions of the primary and secondary-side inner and outer phase shift angles relative to the resonant period. A drive signal generation module is used to generate a control gate drive signal based on the inner phase shift angle, outer phase shift angle, and switching frequency to control the turn-on and turn-off of the primary and secondary-side switches.

9. A computer device, characterized in that, include: Memory and processor; The memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions, which, when executed by the processor, implement the steps of the control method for the resonant isolated active bridge converter according to any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, It stores computer-executable instructions that, when executed by a processor, implement the steps of the control method for the resonant isolated active bridge converter as described in any one of claims 1 to 7.

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