Control circuit for full-bridge resonant converter

Abstract

The application discloses a control circuit based on a full-bridge resonant converter, which comprises a voltage sampling and operation module, a resettable integration module, a first output module and a second output module; the voltage sampling and operation module is used for collecting a first output voltage corresponding to the full-bridge resonant converter and converting the first output voltage into a modulation voltage; the resettable integration module is used for resetting when a corresponding second output voltage is equal to the modulation voltage; the first output module is used for controlling the conduction state of a first control switch and a fourth control switch; and the second output module is used for controlling the conduction state of a second control switch and a third control switch. The control circuit based on the full-bridge resonant converter can guarantee the stability of an output current, reduce the switching loss and improve the charging efficiency.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, and in particular to a control circuit based on a full-bridge resonant converter. Background Technology

[0002] In industrial equipment, new energy storage systems, medical equipment (such as X-ray machines), high-energy physics experimental devices, and power electronic conversion systems, high-voltage capacitors serve as core energy storage components, and the stability and efficiency of their charging process directly affect the performance and lifespan of the equipment.

[0003] In related technologies, full-bridge resonant converters, due to their zero-voltage switching and zero-current switching characteristics and inherent compatibility with parasitic capacitance, possess a wide input voltage range and low loss characteristics. Therefore, full-bridge resonant converters are often used for charging power supplies of high-voltage capacitors. One charging topology of a full-bridge resonant converter is the full-bridge inductor-capacitor-capacitor (LCC) series-parallel resonant converter. When the LCC series-parallel resonant converter operates in the critical discontinuous control mode, its charging characteristics are good, representing an ideal operating state. However, in practical applications, the dynamic changes in the output voltage during capacitor charging cause fluctuations in the resonant period, making it difficult for the LCC series-parallel resonant converter to maintain the critical discontinuous control mode. This results in output current fluctuations, leading to increased switching losses and decreased charging efficiency. Summary of the Invention

[0004] This application provides a control circuit based on a full-bridge resonant converter, which can ensure stable output current, thereby reducing switching losses and improving charging efficiency.

[0005] This application provides a control circuit based on a full-bridge resonant converter. The full-bridge resonant converter includes a first control switch, a second control switch, a third control switch, and a fourth control switch. The first control switch and the second control switch are connected in series and then connected in parallel with the DC source of the full-bridge resonant converter. The third control switch and the fourth control switch are connected in series and then connected in parallel with the DC source of the full-bridge resonant converter.

[0006] The control circuit includes: a voltage sampling and calculation module, a resettable integration module, a first output module, and a second output module;

[0007] The voltage sampling and calculation module is connected to the resettable integrator module. It is used to collect the first output voltage corresponding to the full-bridge resonant converter and determine the modulation voltage based on the first output voltage. It is also used to receive the second output voltage corresponding to the resettable integrator module and control the resettable integrator module to reset when the second output voltage is equal to the modulation voltage.

[0008] The first output module is connected to the resettable integral module and is used to output a first control signal according to the second output voltage to control the conduction state of the first control switch and the fourth control switch.

[0009] The second output module is connected to the voltage sampling and calculation module, the first output module, and the resettable integrator module. It is used to output a second control signal based on the first output voltage and the second output voltage to control the conduction state of the second control switch and the third control switch.

[0010] The control circuit based on a full-bridge resonant converter provided in this application includes a voltage sampling and calculation module responsible for acquiring the first output voltage corresponding to the full-bridge resonant converter and determining the corresponding modulation voltage based on the first output voltage. A resettable integrator module resets when the corresponding second output voltage equals the modulation voltage. Additionally, a first output module outputs a first control signal to control the conduction states of the first and fourth control switches; a second output module outputs a second control signal to control the conduction states of the second and third control switches. Through the control circuit based on the full-bridge resonant converter provided in this application, the modulation voltage can be flexibly adjusted according to the output voltage of the full-bridge resonant converter. This allows the resettable integrator module to adjust the switching cycle based on the reset processing of the modulation voltage, thereby achieving dynamic adjustment of the switching cycle to follow the output voltage of the full-bridge resonant converter. This enables the full-bridge resonant converter to operate in a critical discontinuous control mode, ensuring stable output current, thereby reducing switching losses and improving charging efficiency. Attached Figure Description

[0011] To more clearly illustrate the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 A schematic diagram of an LCC series-parallel resonant converter as an example;

[0013] Figure 2 A schematic diagram of the control circuit based on a full-bridge resonant converter provided in the embodiments of this application. Figure 1 ;

[0014] Figure 3 A schematic diagram of the control circuit based on a full-bridge resonant converter provided in the embodiments of this application. Figure 2 ;

[0015] Figure 4 A schematic diagram of the control circuit based on a full-bridge resonant converter provided in the embodiments of this application. Figure 3 ;

[0016] Figure 5 A schematic diagram of the control circuit based on a full-bridge resonant converter provided in the embodiments of this application. Figure 4 ;

[0017] Figure 6 A schematic diagram of the control circuit based on a full-bridge resonant converter provided in the embodiments of this application. Figure 5 ;

[0018] Figure 7 A schematic diagram of the control circuit based on a full-bridge resonant converter provided in the embodiments of this application. Figure 6 ;

[0019] Figure 8 A schematic diagram of the control circuit based on a full-bridge resonant converter provided in the embodiments of this application. Figure 7 ;

[0020] Figure 9 A schematic diagram of the control circuit based on a full-bridge resonant converter provided in the embodiments of this application. Figure 8 ;

[0021] Figure 10 A schematic diagram of the control circuit based on a full-bridge resonant converter provided in the embodiments of this application. Figure 9 ;

[0022] Figure 11 A schematic diagram of the control circuit based on a full-bridge resonant converter provided in the embodiments of this application. Figure 10 .

[0023] The above figures include the following reference numerals:

[0024] U01: First DC voltage source;

[0025] U02: Resettable integrator;

[0026] U03: First comparator;

[0027] U04: Inverter;

[0028] U05: Arithmetic unit;

[0029] U06: First proportional device;

[0030] U07: Second comparator;

[0031] U08: Second DC voltage source;

[0032] U09: Second proportional device;

[0033] U10: Third comparator;

[0034] U11: Fourth comparator;

[0035] U12: Adder;

[0036] U13: XOR gate device;

[0037] R1: First resistor;

[0038] R2: Second resistor;

[0039] S1: First switching transistor;

[0040] S2: Second switching transistor;

[0041] S3: Third switching transistor;

[0042] S4: Fourth switching transistor;

[0043] D1: First diode;

[0044] D2: Second diode;

[0045] D3: Third diode;

[0046] D4: Fourth diode;

[0047] D5: Fifth diode;

[0048] D6: Sixth diode;

[0049] D7: Seventh diode;

[0050] D8: Eighth diode;

[0051] C1: First capacitor;

[0052] C2: Second capacitor;

[0053] C3: Third capacitor;

[0054] L: Inductance;

[0055] T: Transformer. Detailed Implementation

[0056] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of this application.

[0057] It should be noted that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. The terms "installed," "connected," and "linked" should be interpreted broadly, for example, they can be fixed connections, detachable connections, or integral connections; they can be mechanical connections or electrical connections; they can be direct connections or indirect connections through an intermediate medium; they can be internal connections between two elements. The terms "parallel," "perpendicular," and "equal" include the described situation and situations similar to the described situation, the range of which is within an acceptable deviation range, wherein the acceptable deviation range is determined by those skilled in the art taking into account the measurement under discussion and the error associated with the measurement of a particular quantity (i.e., the limitations of the measurement system). For example, "parallel" includes absolute parallelism and approximate parallelism, where an acceptable deviation range for approximate parallelism can be, for example, within 5°; "perpendicular" includes absolute perpendicularity and approximate perpendicularity, where an acceptable deviation range for approximate perpendicularity can also be, for example, within 5°. "Equal" includes absolute equality and approximate equality, where an acceptable deviation range for approximate equality can be, for example, a difference between the two equal items being less than or equal to 5% of either one. Those skilled in the art will understand the specific meaning of the above terms in this application based on the specific circumstances.

[0058] In industrial equipment, new energy storage systems, medical equipment (such as X-ray machines), high-energy physics experimental devices, and power electronic conversion systems, high-voltage capacitors serve as core energy storage components. The stability and efficiency of their charging process directly affect equipment performance and lifespan. Traditional charging power supplies typically employ constant current mode to ensure linear voltage rise in the capacitors and prevent overvoltage damage. However, the presence of parasitic capacitance in the high-voltage transformer makes it difficult for traditional topologies (such as LLC resonant converters) to simultaneously achieve high efficiency and a wide input voltage range. Full-bridge resonant converters, due to their zero-voltage switching, zero-current switching characteristics, and inherent compatibility with parasitic capacitance, possess a wide input voltage range and low-loss characteristics. Therefore, full-bridge resonant converters are commonly used in high-voltage capacitor charging power supplies. Full-bridge resonant converters include inductor-capacitor (LC) series resonant, LC parallel resonant, LLC series-parallel resonant, and LCC series-parallel resonant converters. Among these, in high-voltage capacitor charging power supplies, since the parasitic capacitance of the high-voltage transformer cannot be ignored, LCC series-parallel resonant converters have become the preferred solution for charging high-voltage capacitors. When the LCC series-parallel resonant converter operates in the critical discontinuous control mode, it exhibits excellent charging characteristics, representing an ideal operating state. However, in practical applications, the dynamic changes in the output voltage during capacitor charging cause fluctuations in the resonant period, making it difficult for the LCC series-parallel resonant converter to maintain the critical discontinuous control mode. This results in output current fluctuations, leading to increased switching losses and decreased charging efficiency.

[0059] Figure 1 A schematic diagram of an LCC series-parallel resonant converter is shown below. Figure 1As shown, the structure of the LCC series-parallel resonant converter includes: a DC source Vin, a first control switch (including a first switch S1 and a first diode D1), a second control switch (including a second switch S2 and a second diode D2), a third control switch (including a third switch S3 and a third diode D3), a fourth control switch (including a fourth switch S4 and a fourth diode D4), an inductor L, a first capacitor C1, a second capacitor C2, a transformer T, a fifth diode D5, a sixth diode D6, a seventh diode D7, an eighth diode D8, and a third capacitor C3. The DC source Vin provides the DC input energy to the entire converter and is the energy source of the LCC series-parallel resonant converter. The first switch S1, the second switch S2, the third switch S3, and the fourth switch S4 can be metal-oxide-semiconductor field-effect transistors (MOSFETs). The first switch S1 and the second switch S2 form the first bridge arm, and the third switch S3 and the fourth switch S4 form the second bridge arm. The gates of the first switch S1 and the fourth switch S4 are connected to the first control signal Vg1,4. When the first control signal Vg1,4 is high, the first switch S1 and the fourth switch S4 are turned on; when the first control signal Vg1,4 is low, the first switch S1 and the fourth switch S4 are turned off. The gates of the second switch S2 and the third switch S3 are connected to the second control signal Vg2,3. When the second control signal Vg2,3 is high, the second switch S2 and the third switch S3 are turned on; when the second control signal Vg2,3 is low, the second switch S2 and the third switch S3 are turned off. The first switch S1 and the fourth switch S4, and the second switch S2 and the third switch S4, alternately conduct, inverting Vin into a high-frequency square wave AC signal. Diodes D1, D2, D3, and D4 are connected in parallel with their corresponding switching transistors. The anodes of the diodes are connected to the sources of the corresponding switching transistors, and the cathodes are connected to the drains of the corresponding switching transistors. The diodes exhibit unidirectional conductivity. Capacitor C1 is connected in series with inductor L, and capacitor C2 is connected in parallel to the primary winding of transformer T. The voltage conversion ratio between the primary and secondary windings of transformer T is 1:n, used for electrical isolation. Diodes D5, D6, D7, and D8 form a full-bridge uncontrolled rectifier circuit. An uncontrolled rectifier circuit is a rectifier circuit composed of diodes without control function. Utilizing the unidirectional conductivity of the diodes, it converts the high-frequency AC voltage on the secondary winding into a pulsating DC voltage. Capacitor C3 is the output capacitor, used to filter the rectified pulsating DC voltage, reducing output ripple and providing a stable DC voltage V0 to the load.

[0060] The control circuit based on a full-bridge resonant converter provided in this application includes a voltage sampling and calculation module responsible for acquiring the first output voltage corresponding to the full-bridge resonant converter, determining the corresponding modulation voltage based on the first output voltage, and a resettable integrator module resetting when the corresponding second output voltage equals the modulation voltage. Additionally, a first output module outputs a first control signal to control the conduction states of a first control switch and a fourth control switch; a second output module outputs a second control signal to control the conduction states of a second control switch and a third control switch. Through the control circuit based on the full-bridge resonant converter provided in this application, the modulation voltage can be flexibly adjusted according to the output voltage of the full-bridge resonant converter. This allows the resettable integrator module to adjust the switching period based on the reset processing of the modulation voltage, enabling the switching period to dynamically adjust in accordance with the output voltage of the full-bridge resonant converter. This allows the full-bridge resonant converter to operate in a critical discontinuous control mode, ensuring stable output current, thereby reducing switching losses and improving charging efficiency.

[0061] To enable those skilled in the art to better understand the present application, the present application will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0062] Figure 2 A schematic diagram of the control circuit based on a full-bridge resonant converter provided in the embodiments of this application. Figure 1 The full-bridge resonant converter includes a first control switch, a second control switch, a third control switch, and a fourth control switch. The first and second control switches are connected in series and then in parallel with the DC source of the full-bridge resonant converter. The third and fourth control switches are connected in series and then in parallel with the DC source of the full-bridge resonant converter. Figure 2 As shown, the control circuit includes: a voltage sampling and calculation module, a resettable integrator module, a first output module, and a second output module. The voltage sampling and calculation module is connected to the resettable integrator module and is used to acquire the first output voltage corresponding to the full-bridge resonant converter and determine the modulation voltage based on the first output voltage. It is also used to receive the second output voltage corresponding to the resettable integrator module and control the resettable integrator module to reset when the second output voltage is equal to the modulation voltage. The first output module is connected to the resettable integrator module and is used to output a first control signal based on the second output voltage to control the conduction state of the first control switch and the fourth control switch. The second output module is connected to the voltage sampling and calculation module, the first output module, and the resettable integrator module and is used to output a second control signal based on the first output voltage and the second output voltage to control the conduction state of the second control switch and the third control switch.

[0063] Based on the scenario example, the first control switch, the second control switch, the third control switch, and the fourth control switch can be as follows: Figure 1As shown, in the first control switch, the gate of the first switch transistor S1 is used to receive the first control signal Vg1,4. The drain of the first switch transistor S1 is connected to the positive terminal of the DC source Vin. The source of the first switch transistor S1 is connected to the drain of the second switch transistor S2 in the second control switch. The source of the second switch transistor S2 is connected to the negative terminal of the DC source Vin. The gate of the second switch transistor S2 is used to receive the second control signal Vg2,3. In the third control switch, the gate of the third switch transistor S3 is used to receive the second control signal Vg2,3. The drain of the third switch transistor S3 is connected to the positive terminal of the DC source Vin. The source of the third switch transistor S3 is connected to the drain of the fourth switch transistor S4 in the fourth control switch. The source of the fourth switch transistor S4 is connected to the negative terminal of the DC source Vin. The gate of the fourth switch transistor S4 is used to receive the first control signal Vg1,4. In the first control switch, the anode of the first diode D1 is connected to the source of the first switching transistor S1, and the cathode of the first diode D1 is connected to the drain of the first switching transistor S1; in the second control switch, the anode of the second diode D2 is connected to the source of the second switching transistor S2, and the cathode of the second diode D2 is connected to the drain of the second switching transistor S2; in the third control switch, the anode of the third diode D3 is connected to the source of the third switching transistor S3, and the cathode of the third diode D3 is connected to the drain of the third switching transistor S3; in the fourth control switch, the anode of the fourth diode D4 is connected to the source of the fourth switching transistor S4, and the cathode of the fourth diode D4 is connected to the drain of the fourth switching transistor S4.

[0064] In the scenario example, the first output voltage acquired by the voltage sampling and calculation module is the voltage corresponding to the third capacitor C3, which can be defined as V0. Based on the first output voltage, the voltage sampling and calculation module determines the reset voltage used by the resettable integrator module, which can be defined as Vi. The voltage sampling and calculation module converts the acquired first output voltage V0 into the magnitude of Vi, and defines the output signal of the voltage sampling and calculation module as the modulation signal. Therefore, the output result of the voltage sampling and calculation module is defined as the modulation voltage Vm, and the magnitude of the modulation voltage Vm is equal to the reset voltage Vi. The second output voltage of the resettable integrator module gradually increases as it charges until it reaches the modulation voltage Vm, which is the reset voltage Vi. After this, a reset occurs, and the second output voltage gradually increases from zero again. This cycle repeats according to a fixed period, which can be defined as the carrier period tc, which is the switching period ts.

[0065] The conduction state of each control switch can be controlled based on the first control signals Vg1,4 output by the first output module and the second control signals Vg2,3 output by the second output module. The first output module outputs the first control signals Vg1,4 to control the conduction state of the first and fourth control switches. When the first control signals Vg1,4 output by the first output module are high, the first and fourth control switches are turned on; when the first control signals Vg1,4 output by the first output module are low, the first and fourth control switches are turned off. The second output module outputs the second control signals Vg2,3 to control the conduction state of the second and third control switches. When the second control signals Vg2,3 output by the second output module are high, the second and third control switches are turned on; when the second control signals Vg2,3 output by the second output module are low, the second and third control switches are turned off.

[0066] In summary, based on the control circuit of the full-bridge resonant converter provided in this example, the corresponding switching period ts can be determined according to the actual first output voltage V0 of the full-bridge resonant converter. This enables the switching period to be dynamically adjusted to follow the output voltage of the full-bridge resonant converter, allowing the full-bridge resonant converter to operate in the critical discontinuous control mode to ensure stable output current, thereby reducing switching losses and improving charging efficiency.

[0067] Optional, Figure 3 A schematic diagram of the control circuit based on a full-bridge resonant converter provided in the embodiments of this application. Figure 2 ,like Figure 3 As shown, the resettable integrator module includes: a first DC voltage source U01, a resettable integrator U02, and a reset control unit; the positive terminal of the first DC voltage source U01 is connected to the first input terminal of the resettable integrator U02 to provide a first input voltage to the resettable integrator U02, and the negative terminal of the first DC voltage source U01 is grounded; the output terminal of the resettable integrator U02 is connected to the first input terminal of the reset control unit to transmit the corresponding second output voltage to the reset control unit; the second input terminal of the reset control unit is connected to the voltage sampling and calculation module, and the output terminal of the reset control unit is connected to the second input terminal of the resettable integrator U02. The reset control unit is used to compare the magnitude of the modulation voltage output by the voltage sampling and calculation module with the magnitude of the corresponding second output voltage of the resettable integrator U02. When the modulation voltage is greater than the second output voltage, a low-level reset signal is output; when the modulation voltage is less than or equal to the second output voltage, a high-level reset signal is output, so that the resettable integrator U02 triggers a reset operation when it receives a high-level reset signal.

[0068] In the scenario example, the first DC voltage source U01 provides a first input voltage to the resettable integrator U02, which can be defined as Vi-dc. The output voltage of the resettable integrator U02 resets the second output voltage of the integrator module. The reset control unit compares the modulation voltage with the second output voltage. When the second output voltage is less than the modulation voltage, it outputs a low-level reset signal; when the second output voltage reaches the modulation voltage, or is less than or equal to the second output voltage, it outputs a high-level reset signal. Upon receiving the high-level reset signal, the resettable integrator U02 triggers a reset operation to return the second output voltage to zero.

[0069] Based on the control circuit provided in this example, the second output voltage can be cyclical according to a fixed period to adjust the switching cycle.

[0070] Optional, Figure 4 A schematic diagram of the control circuit based on a full-bridge resonant converter provided in the embodiments of this application. Figure 3 ,like Figure 4 As shown, the reset control unit includes: a first comparator U03 and an inverter U04; the positive input terminal of the first comparator U03 is connected to the voltage sampling and calculation module, and the inverting input terminal of the first comparator U03 is connected to the output terminal of the resettable integrator U02, for comparing the magnitude of the modulation voltage output by the voltage sampling and calculation module with the magnitude of the second output voltage corresponding to the resettable integrator U02, and outputting a corresponding first level signal, wherein the first level signal is high when the modulation voltage is greater than the second output voltage, and low when the modulation voltage is less than or equal to the second output voltage; the input terminal of the inverter U04 is connected to the output terminal of the first comparator U03, and the output terminal of the inverter U04 is connected to the second input terminal of the resettable integrator U02, for converting the first level signal into a low level reset signal when it is high, or converting the first level signal into a high level reset signal when it is low.

[0071] In a scenario example, the first comparator U03 compares the second output voltage corresponding to the resettable integrator U02 with the modulation voltage output by the voltage sampling and calculation module. When the second output voltage does not reach the modulation voltage, the first comparator U03 outputs a high-level first-level signal, which is converted to a low level after processing by the inverter U04. When the second output voltage reaches the modulation voltage, the first comparator U03 outputs a low-level first-level signal, which is converted to a high level after processing by the inverter U04. Therefore, when the resettable integrator U02 receives a rising-edge reset signal, the carrier signal output by the resettable integrator is reset to zero and integration restarts, thus obtaining a periodic carrier signal.

[0072] Figure 5A schematic diagram of the control circuit based on a full-bridge resonant converter provided in the embodiments of this application. Figure 4 ,like Figure 5 As shown, the voltage sampling and calculation module includes a voltage divider unit and a first calculation unit. The input terminal of the voltage divider unit is used to collect the first output voltage corresponding to the full-bridge resonant converter and output the first proportional voltage according to the corresponding voltage division ratio. The input terminal of the first calculation unit is connected to the output terminal of the voltage divider unit, and the output terminal of the first calculation unit is connected to the positive input terminal of the first comparator U03. It is used to process the first proportional voltage according to a preset algorithm to obtain the modulation voltage.

[0073] Based on the scenario example, the voltage divider unit processes the first output voltage V0 according to the corresponding voltage division ratio. For example, when the voltage division ratio is K, the output first proportional voltage is K×V0. The first arithmetic unit is used to process and calculate the first proportional voltage to obtain the modulation voltage.

[0074] Based on the control circuit provided in this example, a matching modulation voltage can be obtained according to the real-time first output voltage to ensure that the modulation voltage follows the dynamic adjustment of the first output voltage.

[0075] Figure 6 A schematic diagram of the control circuit based on a full-bridge resonant converter provided in the embodiments of this application. Figure 5 ,like Figure 6 As shown, the first arithmetic unit includes: an arithmetic unit U05 and a first proportional unit U06; the input terminal of the arithmetic unit U05 is connected to the output terminal of the voltage divider unit, and is used to restore the first proportional voltage to the first output voltage according to the voltage division ratio, and determine the resonant period corresponding to the first output voltage; the input terminal of the first proportional unit U06 is connected to the output terminal of the arithmetic unit U05, and the output terminal of the first proportional unit U06 is connected to the positive input terminal of the first comparator U03, and is used to determine the first proportional coefficient according to the resonant period, and convert the resonant period into a modulation voltage according to the first proportional coefficient.

[0076] In the scenario example, the arithmetic unit U05 is used to restore the first proportional voltage to the first output voltage according to the voltage division ratio, that is, to multiply the first proportional voltage by the reciprocal of the voltage division ratio to obtain the first output voltage. The relationship between the output voltage and the resonant period is expressed as follows:

[0077]

[0078] in, , ,

[0079] n is the turns ratio of the primary and secondary sides of the transformer, tr is the resonant period, Cp is the parallel resonant capacitor of the converter, which is the capacitance value of the second capacitor C2, Cs is the series resonant capacitor of the converter, which is the capacitance value of the first capacitor C1, Lr is the series resonant inductor of the converter, which is the capacitance value of inductor L, and k is the ratio between Cp and Cs, which is the capacitance ratio coefficient. It is the series resonant angular frequency. This is the equivalent series resonant angular frequency. This is the equivalent series resonant capacitor. The arithmetic unit U05 determines the resonant period tr corresponding to the first output voltage based on the aforementioned expression relating the output voltage and the resonant period.

[0080] To achieve critical discontinuous control, the switching period ts during capacitor charging should be twice the resonant period, therefore the switching period ts = 2tr. Thus, the target ratio between the switching period and the resonant period of the full-bridge resonant converter is ts = 2tr. The second output voltage corresponding to the resettable integrator U02 can be defined as the carrier signal Vc, the time constant of the resettable integrator U02 as Ti, the first voltage corresponding to the first DC voltage source U01 as Vi-dc, the reset voltage of the resettable integrator as Vi, and the period of the carrier signal Vc as the carrier period tc. tc satisfies the following relationship:

[0081]

[0082] Wherein, the carrier period tc is the switching period ts, so the arithmetic unit U05 can obtain the reset voltage Vi based on the target proportional relationship between the first input voltage Vi-dc, the switching period and the resonant period of the full-bridge resonant converter ts=2tr, and the time constant Ti:

[0083]

[0084] The first proportionalizer U06 is used to process the resonant period tr corresponding to the first output voltage to obtain the corresponding modulation voltage. As mentioned above, the modulation voltage is equal to the reset voltage Vi, so the modulation voltage can be defined as Vm, and the first proportional coefficient can be defined as Kp. Therefore:

[0085] Vm=Kp×tr

[0086] Since the modulation voltage Vm is equal to the reset voltage Vi, therefore:

[0087]

[0088] After obtaining the corresponding first proportional coefficient definition Kp, the first proportionalizer U06 converts the resonant period corresponding to the first output voltage into a modulation voltage Vm based on the first proportional coefficient definition Kp. The unit of the first proportional coefficient is V / s, so the resonant period can be multiplied by the first proportional coefficient to obtain the corresponding modulation voltage. Therefore, based on the control circuit provided in this example, the arithmetic unit can determine the resonant period corresponding to the first output voltage, and the first proportionalizer can determine the first proportional coefficient for converting the resonant period into a modulation voltage, thereby realizing the conversion of the resonant period to obtain the resonant period corresponding to the first output voltage.

[0089] Optional, Figure 7 A schematic diagram of the control circuit based on a full-bridge resonant converter provided in the embodiments of this application. Figure 6 ,like Figure 7 As shown, the voltage divider unit includes a first resistor R1 and a second resistor R2; the first end of the first resistor R1 is used to acquire the first output voltage corresponding to the full-bridge resonant converter, the second end of the first resistor R1 is connected to the first end of the second resistor R2, and the second end of the second resistor R2 is grounded.

[0090] In the example scenario, the first output voltage V0 is divided by a series resistor R1 and a second resistor R2. Therefore, the voltage division ratio of the voltage divider unit is determined by the resistance values ​​of the first resistor R1 and the second resistor R2, specifically the ratio of the resistance value of the first resistor R1 to the total resistance of the two resistors. Based on the circuit provided in this example, voltage division of the first output voltage can be achieved by connecting resistors in series.

[0091] Optional, Figure 8 A schematic diagram of the control circuit based on a full-bridge resonant converter provided in the embodiments of this application. Figure 7 ,like Figure 8 As shown, the first output module includes a second comparator U07 and a second DC voltage source U08; the positive terminal of the second DC voltage source U08 is connected to the positive input terminal of the second comparator U07 to provide a second input voltage to the second comparator U07, and the negative terminal of the second DC voltage source U08 is grounded; the negative input terminal of the second comparator U07 is connected to the output terminal of the resettable integrator U02 to compare the magnitude of the second input voltage with the second output voltage corresponding to the resettable integrator U02, and outputs a high-level first control signal when the second input voltage is greater than the second output voltage, and outputs a low-level first control signal when the second input voltage is less than or equal to the second output voltage.

[0092] In the example scenario, the second comparator U07 is mainly used to compare the second input voltage provided by the second DC voltage source U08 with the actual second output voltage of the resettable integrator U02. When the second input voltage is larger, the output first control signal Vg1,4 is at a high level; when the second output voltage is greater than or equal to the second input voltage, the output first control signal Vg1,4 is at a low level. Based on the circuit provided in this example, the conduction states of the first control switch and the fourth control switch can be controlled through the second comparator U07 and the second DC voltage source U08.

[0093] Optional, Figure 9 A schematic diagram of the control circuit based on a full-bridge resonant converter provided in the embodiments of this application. Figure 8 ,like Figure 9 As shown, the second output module includes: a second proportionalizer U09, a third comparator U10, a fourth comparator U11, a second arithmetic unit, and a third arithmetic unit. The input terminal of the second proportionalizer U09 is connected to the output terminal of the first proportionalizer U06, and it reduces the modulation voltage to obtain the corresponding third output voltage, wherein the third output voltage is half of the modulation voltage. The positive input terminal of the third comparator U10 is connected to the output terminal of the resettable integrator U02, and the inverting input terminal of the third comparator U10 is connected to the output terminal of the second proportionalizer U09. It is used to compare the magnitude of the second output voltage corresponding to the resettable integrator U02 with the third output voltage, and output the corresponding second level signal. When the second output voltage is greater than the third output voltage, the second level signal is high; when the second output voltage is less than or equal to the third output voltage, the second level signal is low. The first input terminal of the second arithmetic unit is connected to the output terminal of the second proportionalizer U09. The second input terminal of the second arithmetic unit is connected to the positive terminal of the second DC voltage source U08, and is used to perform calculations on the third output voltage and the second input voltage to obtain the corresponding fourth output voltage. The positive input terminal of the fourth comparator U11 is connected to the output terminal of the resettable integrator U02, and the inverting input terminal of the fourth comparator U11 is connected to the output terminal of the second arithmetic unit, and is used to compare the magnitudes of the second output voltage and the fourth output voltage corresponding to the resettable integrator U02, and output the corresponding third level signal. When the second output voltage is greater than the fourth output voltage, the third level signal is high, and when the second output voltage is less than or equal to the fourth output voltage, the third level signal is low. The first input terminal of the third arithmetic unit is connected to the output terminal of the fourth comparator U11, and the second input terminal of the third arithmetic unit is connected to the output terminal of the third comparator U10, and is used to perform calculations on the second level signal and the third level signal to output the second control signal.

[0094] In the example scenario, the second proportionalizer U09 reduces the modulated voltage to half its original value to obtain the third output voltage. The third comparator U10 is mainly used to compare the third output voltage with the second output voltage. When the second output voltage is larger, it outputs a high-level second-level signal; conversely, when the third output voltage is greater than or equal to the second output voltage, it outputs a low-level second-level signal. The second arithmetic unit is used to perform calculations on the third output voltage and the second input voltage to output a fourth output voltage. Optionally, Figure 10 A schematic diagram of the control circuit based on a full-bridge resonant converter provided in the embodiments of this application. Figure 9 ,like Figure 10 As shown, the second arithmetic unit includes an adder U12; the first input terminal of the adder U12 is connected to the second terminal of the second proportional U09, and the second input terminal of the adder U12 is connected to the positive terminal of the second DC voltage source U08, for adding the third output voltage to the second input voltage to output the fourth output voltage.

[0095] In the example scenario, adder U12 is used to add the third output voltage to the second input voltage to output a fourth output voltage. Adding the third output voltage to the second input voltage allows for a 180° phase shift of the second input voltage.

[0096] Additionally, the fourth comparator U11 is mainly used to compare the magnitude of the fourth output voltage with the second output voltage. When the second output voltage is larger, it outputs a high-level third-level signal; conversely, when the fourth output voltage is greater than or equal to the second output voltage, it outputs a low-level third-level signal. The third arithmetic unit processes the second-level and third-level signals to output the second control signal. Optionally, Figure 11 A schematic diagram of the control circuit based on a full-bridge resonant converter provided in the embodiments of this application. Figure 10 ,like Figure 11As shown, the second operational unit includes an XOR gate U13. The first input of the XOR gate U13 is connected to the output of the fourth comparator U11, and the second input is connected to the output of the third comparator U10. It is used to output a low-level second control signal when both the second and third level signals are high or both are low. It is also used to output a high-level second control signal when the second level signal is high and the third level signal is low, or when the second level signal is low and the third level signal is high. The XOR gate U13 performs an XOR operation on the second and third level signals. When the second and third level signals are the same, the output second control signal Vg2,3 is low; when the second and third level signals are opposite, the output second control signal Vg2,3 is high. Based on the circuit provided in this example, the conduction states of the second and third control switches can be controlled. Furthermore, after the second proportionalizer reduces the modulation voltage to half of its original value, the phase difference between the first and second control signals can be 180°, providing a safe and symmetrical control signal for the LCC series-parallel resonant converter, so that the first and fourth control switches are alternately turned on with the second and third control switches.

[0097] According to the control circuit based on the full-bridge resonant converter provided in this embodiment, the reset voltage and modulation voltage can be flexibly adjusted according to the output voltage of the full-bridge resonant converter. This allows the resettable integrator module to adjust the switching cycle based on the reset processing of the modulation voltage. The switching cycle can then dynamically adjust to follow the output voltage of the full-bridge resonant converter, enabling the full-bridge resonant converter to operate in the critical discontinuous control mode to ensure stable output current, thereby reducing switching losses and improving charging efficiency.

[0098] The division of units in this application is merely a logical functional division. In actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0099] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0100] Any of the components, modules, units, parts, methods, and operations described herein can be implemented using software, firmware, hardware (e.g., fixed logic circuitry), manual processing, or any combination thereof. Alternatively or additionally, any functionality described herein can be executed at least in part by one or more hardware logic components, such as, but not limited to, a central processing unit (CPU), a field-programmable gate array (FPGA), an application-specific integrated circuit (ASIC), an application-specific standard product (ASSP), a system-on-a-chip (SoC), a complex programmable logic device (CPLD), a microcontroller unit (MCU), etc. The terms "system," "computing device," or "apparatus" as used herein encompass various means, devices, and machines for processing data, including, for example, one or more programmable processors, computers, SoCs, or combinations thereof. The apparatus may also include code that creates an execution environment for the computer program in question, such as code constituting processor firmware, a protocol stack, a database management system, an operating system, a cross-platform runtime environment, a virtual machine, or a combination thereof. The aforementioned computer program (also known as a program, software, software application, app, script, or code) can be written in any form of programming language, including compiled or interpreted languages, declarative or procedural languages, and can be deployed in any form, including as a standalone program or as a module, component, subroutine, object, or other unit suitable for a computing environment.

[0101] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0102] The control circuit based on a full-bridge resonant converter provided in this application has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The descriptions of the embodiments above are only intended to help understand the method and core ideas of this application. It should be noted that those skilled in the art can make various improvements and modifications to this application without departing from its principles, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A control circuit based on a full-bridge resonant converter, characterized in that, The full-bridge resonant converter includes: a first control switch, a second control switch, a third control switch and a fourth control switch, wherein the first control switch and the second control switch are connected in series and then connected in parallel with the DC source of the full-bridge resonant converter, and the third control switch and the fourth control switch are connected in series and then connected in parallel with the DC source of the full-bridge resonant converter; The control circuit includes: a voltage sampling and calculation module, a resettable integration module, a first output module, and a second output module; The voltage sampling and calculation module is connected to the resettable integrator module and is used to collect the first output voltage corresponding to the full-bridge resonant converter and determine the modulation voltage based on the first output voltage. It is also used to receive the second output voltage corresponding to the resettable integrator module and control the resettable integrator module to reset when the second output voltage is equal to the modulation voltage. The first output module is connected to the resettable integrator module and is used to output a first control signal according to the second output voltage to control the conduction state of the first control switch and the fourth control switch; The second output module is connected to the voltage sampling and calculation module, the first output module and the resettable integrator module, and is used to output a second control signal according to the first output voltage and the second output voltage to control the conduction state of the second control switch and the third control switch.

2. The control circuit according to claim 1, characterized in that, The resettable integrator module includes: a first DC voltage source (U01), a resettable integrator (U02), and a reset control unit; The positive terminal of the first DC voltage source (U01) is connected to the first input terminal of the resettable integrator (U02) to provide a first input voltage to the resettable integrator (U02), and the negative terminal of the first DC voltage source (U01) is grounded; The output terminal of the resettable integrator (U02) is connected to the first input terminal of the reset control unit, and is used to transmit the corresponding second output voltage to the reset control unit; The second input terminal of the reset control unit is connected to the voltage sampling and calculation module, and the output terminal of the reset control unit is connected to the second input terminal of the resettable integrator (U02). The reset control unit is used to compare the magnitude of the modulation voltage output by the voltage sampling and calculation module with the magnitude of the second output voltage corresponding to the resettable integrator (U02). When the modulation voltage is greater than the second output voltage, a low-level reset signal is output, and when the modulation voltage is less than or equal to the second output voltage, a high-level reset signal is output, so that the resettable integrator (U02) triggers a reset operation when it receives a high-level reset signal.

3. The control circuit according to claim 2, characterized in that, The reset control unit includes: a first comparator (U03) and an inverter (U04). The positive input terminal of the first comparator (U03) is connected to the voltage sampling and calculation module, and the inverting input terminal of the first comparator (U03) is connected to the output terminal of the resettable integrator (U02). It is used to compare the magnitude of the modulation voltage output by the voltage sampling and calculation module with the magnitude of the second output voltage corresponding to the resettable integrator (U02), and output a corresponding first level signal. When the modulation voltage is greater than the second output voltage, the first level signal is high level, and when the modulation voltage is less than or equal to the second output voltage, the first level signal is low level. The input terminal of the inverter (U04) is connected to the output terminal of the first comparator (U03), and the output terminal of the inverter (U04) is connected to the second input terminal of the resettable integrator (U02), for converting the first level signal into a low-level reset signal when the first level signal is high, or converting the first level signal into a high-level reset signal when the first level signal is low.

4. The control circuit according to claim 3, characterized in that, The voltage sampling and calculation module includes a voltage divider unit and a first calculation unit; The input terminal of the voltage divider unit is used to acquire the first output voltage corresponding to the full-bridge resonant converter, and output the first proportional voltage according to the corresponding voltage division ratio; The input terminal of the first arithmetic unit is connected to the output terminal of the voltage divider unit, and the output terminal of the first arithmetic unit is connected to the positive input terminal of the first comparator (U03), which is used to process the first proportional voltage according to a preset algorithm to obtain the modulation voltage.

5. The control circuit according to claim 4, characterized in that, The first arithmetic unit includes: an arithmetic unit (U05) and a first proportional unit (U06); The input terminal of the arithmetic unit (U05) is connected to the output terminal of the voltage divider unit, and is used to restore the first proportional voltage to the first output voltage according to the voltage division ratio, and determine the resonance period corresponding to the first output voltage; The input terminal of the first proportionalizer (U06) is connected to the output terminal of the arithmetic unit (U05), and the output terminal of the first proportionalizer (U06) is connected to the positive input terminal of the first comparator (U03). It is used to determine the first proportional coefficient based on the resonant period and convert the resonant period into the modulation voltage according to the first proportional coefficient.

6. The control circuit according to claim 5, characterized in that, The voltage divider unit includes a first resistor (R1) and a second resistor (R2); The first end of the first resistor (R1) is used to acquire the first output voltage corresponding to the full-bridge resonant converter. The second end of the first resistor (R1) is connected to the first end of the second resistor (R2), and the second end of the second resistor (R2) is grounded.

7. The control circuit according to claim 6, characterized in that, The first output module includes a second comparator (U07) and a second DC voltage source (U08); The positive terminal of the second DC voltage source (U08) is connected to the positive input terminal of the second comparator (U07) to provide a second input voltage to the second comparator (U07), and the negative terminal of the second DC voltage source (U08) is grounded; The negative input terminal of the second comparator (U07) is connected to the output terminal of the resettable integrator (U02) to compare the magnitude of the second input voltage with the second output voltage corresponding to the resettable integrator (U02). When the second input voltage is greater than the second output voltage, a high-level first control signal is output, and when the second input voltage is less than or equal to the second output voltage, a low-level first control signal is output.

8. The control circuit according to claim 7, characterized in that, The second output module includes: a second proportional unit (U09), a third comparator (U10), a fourth comparator (U11), a second arithmetic unit, and a third arithmetic unit; The input terminal of the second proportionalizer (U09) is connected to the output terminal of the first proportionalizer (U06), and the modulation voltage is reduced to obtain a corresponding third output voltage, wherein the third output voltage is half of the modulation voltage; The positive input terminal of the third comparator (U10) is connected to the output terminal of the resettable integrator (U02), and the inverting input terminal of the third comparator (U10) is connected to the output terminal of the second proportionalizer (U09). It is used to compare the magnitude of the second output voltage corresponding to the resettable integrator (U02) with the magnitude of the third output voltage, and output a corresponding second level signal. When the second output voltage is greater than the third output voltage, the second level signal is high level, and when the second output voltage is less than or equal to the third output voltage, the second level signal is low level. The first input terminal of the second arithmetic unit is connected to the output terminal of the second proportional device (U09), and the second input terminal of the second arithmetic unit is connected to the positive terminal of the second DC voltage source (U08). It is used to perform arithmetic processing on the third output voltage and the second input voltage to obtain the corresponding fourth output voltage. The positive input terminal of the fourth comparator (U11) is connected to the output terminal of the resettable integrator (U02), and the inverting input terminal of the fourth comparator (U11) is connected to the output terminal of the second arithmetic unit. It is used to compare the magnitude of the second output voltage corresponding to the resettable integrator (U02) with the magnitude of the fourth output voltage, and output a corresponding third level signal. When the second output voltage is greater than the fourth output voltage, the third level signal is high level, and when the second output voltage is less than or equal to the fourth output voltage, the third level signal is low level. The first input terminal of the third arithmetic unit is connected to the output terminal of the fourth comparator (U11), and the second input terminal of the third arithmetic unit is connected to the output terminal of the third comparator (U10). It is used to perform arithmetic processing on the second level signal and the third level signal to output the second control signal.

9. The control circuit according to claim 8, characterized in that, The second arithmetic unit includes: an adder (U12); The first input terminal of the adder (U12) is connected to the second terminal of the second proportional device (U09), and the second input terminal of the adder (U12) is connected to the positive terminal of the second DC voltage source (U08) to add the third output voltage to the second input voltage to output the fourth output voltage.

10. The control circuit according to claim 9, characterized in that, The second arithmetic unit includes: an XOR gate device (U13); The first input terminal of the XOR gate device (U13) is connected to the output terminal of the fourth comparator (U11), and the second input terminal of the XOR gate device (U13) is connected to the output terminal of the third comparator (U10). It is used to output a low-level second control signal when both the second level signal and the third level signal are high or both are low. It is also used to output a high-level second control signal when the second level signal is high and the third level signal is low, or when the second level signal is low and the third level signal is high.

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