Driving circuit for LLC resonant converter

Abstract

The present application provides a driving circuit for an LLC resonant converter (200). The driving circuit comprises: a driving signal generation circuit (601), a driving detection circuit (602), a power driving circuit (603), and an auxiliary power supply (Vdrv). The power driving circuit is used for providing a gate driving signal for the LLC resonant converter. The driving detection circuit is used for detecting whether a voltage at a first common node (G1) or a second common node (G2) in a driver bridge of the power driving circuit is greater than or less than threshold voltages (Vth) corresponding to a plurality of switches in the LLC resonant converter, and outputting an indication signal for representing the magnitude relationship between the voltages. The driving signal generation circuit is used for receiving the indication signal, and on the basis of the indication signal, adjusting gate pulse signals corresponding to upper switches in the driver bridge in the power driving circuit, so that the frequency of the indication signal received by the driving signal generation circuit is equal to the resonant frequency corresponding to the LLC resonant converter. The auxiliary power supply is used for providing a driving voltage for the power driving circuit. The driving circuit can improve the conversion efficiency consistency of LLC resonant converters.

Description

A driving circuit for LLC resonant converter

[0001] The present application claims priority to the Chinese patent application No. 202410653475.4, filed on May 23, 2024, and entitled "A driving circuit for LLC resonant converter", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] Embodiments of the present application relate to the field of power converter, and in particular, to a driving circuit for LLC resonant converter. BACKGROUND

[0003] A telecom network power system usually includes an AC-DC stage converter that converts power from an AC utility line to a 48V DC distribution bus and DC-DC stage converters that convert the 48V DC distribution bus to multiple voltage levels for all types of telecom loads. The DC-DC stage converters can be implemented by different topologies, including flyback converter, forward converter, half-bridge converter, full-bridge converter and LLC resonant converter, etc.

[0004] In the LLC resonant converter, the resonant inductance, resonant capacitance and magnetizing inductance in the resonant tank form a resonant process. When the switches in the switching network work at a switching frequency that is approximately equal to the resonant frequency of the resonant tank, the resonant tank helps to achieve zero voltage switching (ZVS) of the primary side switches and zero-current switching (ZCS) of the secondary side switches, which can greatly reduce the switching power loss of the LLC resonant converter, thereby improving the conversion efficiency of the LLC resonant converter. The switching frequency of the switches in the switching network is affected by the gate drive signals of the switches. The switches in the LLC resonant converter are driven by a driving circuit, which includes a driving bridge. The midpoints of the bridge arms in the driving bridge provide gate drive signals for the switches in the LLC resonant converter. The gate drive capacitance of the switches in the switching network and the magnetizing inductance also form a resonant process, which affects the voltage at the midpoints of the driving bridge arms.

[0005] The gate capacitance of the switch in the LLC resonant converter is affected by production process, assembly process, permeability of the driving transformer and dielectric sheet tolerance, etc., and thus the gate capacitance deviation is generated. The gate capacitance deviation will affect the resonant period of the driving bridge arm midpoint, and further affect the switching frequency of the switch in the LLC resonant converter. This will cause the switching frequency deviation of the switch in the LLC resonant converter, and the problem that the switching frequency is inconsistent with the resonant frequency of the resonant tank. In this way, the LLC resonant converter will generate switching power loss, and thus the efficiency consistency of the LLC resonant converter is inconsistent. Therefore, how to ensure the conversion efficiency consistency of the LLC resonant converter becomes a problem to be solved. SUMMARY

[0006] The embodiment of the present application provides a driving circuit and frequency optimization circuit for an LLC resonant converter. The switching frequency of each switch in the main power circuit is determined by detecting the frequency at which the voltage of the driving bridge arm midpoint reaches the threshold voltage of the switch in the LLC resonant converter. Then, the switching frequency of each switch in the main power circuit is restored to the resonant frequency of the resonant cavity in the main power circuit by adjusting the gate pulse signal of each driving switch in the driving bridge according to the switching frequency of each switch in the main power circuit, so as to ensure the efficiency consistency of the LLC resonant converter, and further improve the conversion efficiency of the LLC resonant converter.

[0007] In a first aspect, the embodiment of the present application provides a driving circuit coupled to an LLC resonant converter. The inverter circuit in the LLC resonant converter includes a plurality of switches, i.e. a first high-side switch, a first low-side switch, a second high-side switch and a second low-side switch. The driving circuit is used to provide a gate drive signal for the switches. Specifically, the driving circuit is composed of a driving signal generation circuit, a driving detection circuit, a power driving circuit and an auxiliary power supply. The auxiliary power supply is used to provide a bias voltage for the power driving module. The power driving circuit includes a driving bridge coupled between the bias voltage and the ground, and the driving bridge is used to be coupled to the LLC resonant converter. The driving bridge includes a switch Q1 and a switch Q2 connected in series and coupled between the bias voltage and the ground, and a switch Q3 and a switch Q4 connected in series and coupled between the bias voltage and the ground. The common node G1 between the switch Q1 and the switch Q2 is connected to the gate of the first high-side switch and the second low-side switch to provide a gate drive signal for them. The common node G2 between the switch Q3 and the switch Q4 is connected to the gate of the first low-side switch and the second high-side switch to provide a gate drive signal for them.

[0008] The drive detection circuit is configured to detect whether the voltage at the common node G1 or the common node G2 is greater than or less than a threshold voltage Vth corresponding to the plurality of switches in the inverter circuit, and output an indication signal indicating the greater-than relationship when the voltage at the common node G1 or the common node G2 is greater than the threshold voltage Vth, and also output an indication signal indicating the less-than relationship when the voltage at the common node G1 or the common node G2 is greater than the threshold voltage Vth. The drive signal generation circuit is configured to adjust the gate pulse signal corresponding to the upper tube (switch Q1 or switch Q3) in the drive bridge according to the received indication signal, so that the frequency of the indication signal received by the drive signal generation circuit is equal to the resonant frequency of the resonant converter.

[0009] In the embodiments of the present application, when the drive detection circuit detects that the voltage at the common node G1 or the common node G2 is greater than the threshold voltage Vth, the switches of the inverter circuit in the LLC resonant converter are turned on, and when the voltage at the common node G1 or the common node G2 is less than the threshold voltage Vth, the switches of the inverter circuit in the LLC resonant converter are turned off. Therefore, the drive signal generation circuit can determine the on duration of the switches of the inverter circuit according to the received indication signal, and further obtain the corresponding switching frequency. In this way, the on duration of the upper tube in the drive bridge can be adjusted to adjust the driving capability of the drive bridge, and further affect the switching frequency of the switches in the inverter circuit, so that the switching frequency is restored to be consistent with the resonant frequency of the LLC resonant converter. In this way, the LLC resonant converter can reduce the switching loss, ensure the efficiency consistency of the LLC resonant converter, and further improve the conversion efficiency of the LLC resonant converter.

[0010] In an optional embodiment, the drive detection circuit can be composed of a comparator. Specifically, the drive detection circuit includes a first comparator and a second comparator. The first comparator is configured to detect the voltage value corresponding to the midpoint of one bridge arm in the drive bridge, i.e., the common node G1. The second comparator is configured to detect the voltage value corresponding to the midpoint of the other bridge arm in the drive bridge, i.e., the common node G2. Specifically, the first end of the first comparator is configured to input the voltage value corresponding to the common node G1, and the second end is configured to input the threshold voltage Vth. The first end of the second comparator is configured to input the voltage value corresponding to the common node G2, and the second end is configured to input the threshold voltage Vth.

[0011] When the voltage value corresponding to the common node G1 is greater than the threshold voltage Vth, the first comparator outputs a first indication signal. When the voltage value corresponding to the common node G1 is less than the threshold voltage Vth, the first comparator outputs a second indication signal. When the voltage value corresponding to the common node G2 is greater than the threshold voltage Vth, the second comparator outputs a third indication signal. When the voltage value corresponding to the common node G2 is less than the threshold voltage Vth, the second comparator outputs a fourth indication signal. The comparator is used to detect the voltage, and has a simple circuit structure, low cost, and high detection performance.

[0012] In an optional embodiment, when the driving signal generation circuit receives the first indication signal and the second indication signal output by the first comparator, it can determine a first interval duration between the reception of the first indication signal and the second indication signal according to the time of reception. It can be understood that, during the first interval duration, the voltage value corresponding to the common node G1 is greater than the threshold voltage Vth, that is, the first interval duration is the conduction duration of the first high-side switch and the second low-side switch in the inverter circuit. Thus, the first frequency value, that is, the switching frequency value of the first high-side switch and the second low-side switch, can be determined according to the first interval duration. Then, the driving signal generation circuit can adjust the gate pulse signal corresponding to the switch Q1 according to the size relationship between the switching frequency value and the resonant frequency corresponding to the LLC resonant converter, thereby affecting the resonant voltage at the common node G1, thereby affecting the switching frequency of the first high-side switch and the second low-side switch, so that the switching frequency value returns to be equal to the resonant frequency, thereby ensuring the efficiency consistency of the LLC resonant converter.

[0013] In an optional embodiment, when the driving signal generation circuit receives the third indication signal and the fourth indication signal output by the second comparator, it can determine a second interval duration between the reception of the third indication signal and the fourth indication signal according to the time of reception. It can be understood that, during the second interval duration, the voltage value corresponding to the common node G2 is greater than the threshold voltage Vth, that is, the second interval duration is the conduction duration of the second high-side switch and the first low-side switch in the inverter circuit. Thus, the second frequency value, that is, the switching frequency value of the second high-side switch and the first low-side switch, can be determined according to the second interval duration. Then, the driving signal generation circuit can adjust the gate pulse signal corresponding to the switch Q3 according to the size relationship between the switching frequency value and the resonant frequency corresponding to the LLC resonant converter, thereby affecting the resonant voltage at the common node G2, thereby affecting the switching frequency of the second high-side switch and the first low-side switch, so that the switching frequency value returns to be equal to the resonant frequency, thereby ensuring the efficiency consistency of the LLC resonant converter.

[0014] In an optional embodiment, when the switching frequency of the first high-side switch and the second low-side switch or the switching frequency of the second high-side switch and the first low-side switch is less than the corresponding resonant frequency of the LLC resonant converter, the width of the pulse in the gate pulse signal corresponding to the switch Q1 or the switch Q3 needs to be reduced. In this way, the on time of the first high-side switch and the second low-side switch is shortened, and thus the switching frequency is increased to the corresponding resonant frequency of the LLC resonant converter.

[0015] When the switching frequency of the first high-side switch and the second low-side switch or the switching frequency of the second high-side switch and the first low-side switch is greater than the corresponding resonant frequency of the LLC resonant converter, the width of the pulse in the gate pulse signal corresponding to the switch Q1 or the switch Q3 needs to be increased. In this way, the on time of the first high-side switch and the second low-side switch is lengthened, and thus the switching frequency is decreased to the corresponding resonant frequency of the LLC resonant converter. The efficiency consistency of the LLC resonant converter is ensured.

[0016] In an optional embodiment, the drive detection circuit is further configured to detect the time when the voltage at the common node G1 or the common node G2 reaches the bias voltage. Specifically, the second end of the first comparator and the second comparator is further configured to input the bias voltage. In this way, when the voltage value corresponding to the common node G1 is equal to the bias voltage, the first comparator outputs a fifth indication signal to the drive signal generation circuit. When the voltage value corresponding to the common node G2 is equal to the bias voltage, the second comparator outputs a sixth indication signal to the drive signal generation circuit. It can be understood that when the voltage at the common node G1 or the common node G2 reaches the bias voltage, the upper tube in the drive bridge is re-conducted to achieve zero voltage switching (ZVS), that is, the upper tube is conducted under the condition of no voltage difference between the source and the drain. Therefore, the drive detection circuit can determine the time when the voltage at the common node G1 or the common node G2 reaches the bias voltage, and then the drive signal generation circuit can adjust the conduction time of the switch Q1 and Q3 according to the time to reduce the switching loss of the drive bridge.

[0017] In an optional embodiment, when the drive signal generation circuit obtains the fifth indication signal or the sixth indication signal output by the drive detection circuit, the starting time of the pulse in the gate pulse signal corresponding to the switch Q1 needs to be adjusted to the receiving time of the fifth indication signal. Or the starting time of the pulse in the gate pulse signal corresponding to the switch Q3 needs to be adjusted to the receiving time of the sixth indication signal. In this way, the switch Q1 and the switch Q3 can achieve ZVS, specifically, the source and the drain of the switch Q1 and the switch Q3 have no voltage difference in the conduction state. In this way, the switching loss in the drive bridge can be reduced, and thus the driving performance of the drive bridge is improved.

[0018] In an optional embodiment, the pulse width of the gate pulse signal corresponding to the switch Q1 and the switch Q3 cannot be infinitely increased or decreased, and therefore the driving signal generation circuit can further reduce the driving loss of the driving circuit by adjusting the bias voltage through the auxiliary power supply.

[0019] In an optional embodiment, when the driving signal generation circuit determines that the switching frequency of the first high-side switch and the second low-side switch is greater than the corresponding resonant frequency of the LLC resonant converter through the first frequency value, the pulse width of the gate pulse signal corresponding to the switch Q1 is first increased. When the duty cycle of the gate pulse signal reaches a first preset duty cycle, the switching frequency of the main power circuit cannot be adjusted any more. At this time, the zero voltage switching (ZVS) of the switch Q1 (driving tube) in the driving circuit can be realized by reducing the bias voltage Vdrv, and specifically, the switch Q1 is turned on when the source-drain voltage of the switch Q1 is Vdrv. The driving loss is further reduced. When the switching frequency of the first high-side switch and the second low-side switch is less than the corresponding resonant frequency of the LLC resonant converter, the pulse width of the gate pulse signal corresponding to the switch Q1 is first decreased. When the duty cycle of the gate pulse signal reaches a second preset duty cycle, the switching frequency of the main power circuit cannot be adjusted any more. At this time, the driving generation module needs to control the auxiliary power supply to increase the size of the bias voltage, so as to realize the zero voltage switching (ZVS) of the switch Q1 (driving tube) in the driving circuit, and further reduce the driving loss. Similarly, the switch Q3 is also the same, which will not be described here.

[0020] In a second aspect, the embodiments of the present application provide a direct current converter, which comprises an LLC resonant converter and the driving circuit provided in the first aspect and any one of the embodiments of the first aspect.

[0021] The LLC resonant converter comprises an inverter circuit, and the driving circuit is configured to provide a gate driving signal for a switch in the inverter circuit.

[0022] In a third aspect, the embodiments of the present application provide an integrated power supply module. The integrated power supply module comprises a power supply module, a control module, and a power supply conversion module.

[0023] The power supply module and the control module are connected with the power supply conversion module. The control module is configured to control the start and shutdown of the power supply conversion module, and the power supply conversion module is configured to perform DC-DC conversion on the direct current output by the power supply module.

[0024] For example, the power supply conversion module comprises an LLC resonant converter and the driving circuit provided in the first aspect and any one of the embodiments of the first aspect. The LLC resonant converter comprises an inverter circuit, and the driving circuit is configured to provide a gate driving signal for a switch in the inverter circuit.

[0025] In a fourth aspect, an electronic device is provided. The electronic device comprises a power supply and a DC converter.

[0026] The DC converter is connected to the power supply and converts the voltage outputted by the power supply into a supply voltage for the load.

[0027] The power supply can be, but is not limited to, a battery or a vehicle power supply.

[0028] Optionally, the electronic device can be a switching power supply, which is connected to the battery and the load respectively.

[0029] The switching power supply receives the battery voltage provided by the battery and converts the battery voltage into a working voltage for the load, and then outputs the working voltage to the load.

[0030] The DC converter comprises an LLC resonant converter and a driving circuit as provided in the first aspect and any one of the embodiments of the first aspect. The LLC resonant converter comprises an inverter circuit, and the driving circuit is configured to provide a gate drive signal for the switches in the inverter circuit. BRIEF DESCRIPTION OF DRAWINGS

[0031] FIG. 1 is a block diagram of an LLC resonant converter according to an embodiment of the present application;

[0032] FIG. 2 is a structural schematic diagram of an LLC resonant converter according to an embodiment of the present application;

[0033] FIG. 3 is a structural schematic diagram of a driving circuit according to an embodiment of the present application;

[0034] FIG. 4 is a switching waveform diagram of a driving circuit according to an embodiment of the present application;

[0035] FIG. 5 is a switching waveform diagram of another driving circuit according to an embodiment of the present application;

[0036] FIG. 6 is a structural schematic diagram of a driving circuit for an LLC resonant converter according to an embodiment of the present application;

[0037] FIG. 7 is a structural schematic diagram of an integrated power supply module according to an embodiment of the present application;

[0038] FIG. 8 is a structural schematic diagram of an electronic device according to an embodiment of the present application.

[0039] Explanation of reference signs: 101: input DC power supply; 102: inverter circuit; 104: resonance tank; 111: load; 112: transformer; 114: rectifier; 116: output filter; 200: LLC resonance converter; 202: driver; 601: drive signal generation circuit; 602: drive detection circuit; 603: power drive circuit; 604: auxiliary power supply; 801: power supply module; 802: control module; 803: power conversion module. DETAILED DESCRIPTION

[0040] The embodiment of the present application provides a driving circuit and a frequency optimization circuit for an LLC resonance converter. The switching frequency of each switch in a main power circuit is determined by detecting the frequency at which the voltage of a driving bridge arm midpoint reaches the threshold voltage of a switch in the LLC resonance converter. Then, the switching frequency of each switch in the main power circuit is restored to the resonance frequency of a resonance cavity in the main power circuit by adjusting the gate pulse signal of each driving switch in the driving bridge according to the switching frequency of each switch in the main power circuit, so that the efficiency consistency of the LLC resonance converter is ensured, and the conversion efficiency of the LLC resonance converter is improved.

[0041] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0042] The term "and / or" in the present application is only used to describe the association relationship of the associated objects, and means that there can be three relationships, for example, A and / or B can mean that A exists alone, A and B exist together, and B exists alone.

[0043] The terms "first" and "second" and the like in the specification and claims of the embodiments of the present application are used to distinguish different objects, and are not used to describe a specific order of the objects. For example, the first target object and the second target object are used to distinguish different target objects, and are not used to describe a specific order of the target objects.

[0044] In the embodiments of the present application, the words such as "exemplary" or "for example" are used to mean by way of example, illustration or description. Any embodiment or design scheme described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as more preferred or more advantageous than other embodiments or design schemes. Rather, the words such as "exemplary" or "for example" are intended to present the relevant concept in a specific manner.

[0045] In the description of the embodiments of the present application, the meaning of "a plurality of" is two or more, unless otherwise specified. For example, a plurality of processing units means two or more processing units; a plurality of systems means two or more systems.

[0046] The driving circuit for the LLC resonant converter is described below in connection with preferred embodiments in specific environments. It can be understood that the driving circuit provided by the embodiments of the present application can also be applied to other resonant converters.

[0047] FIG. 1 is a block diagram of an LLC resonant converter provided by the embodiments of the present application. The LLC resonant converter 200 is coupled between an input DC power source 101 and a load 111, and is used for DC-DC conversion. Specifically, the input DC power source 101 can be a telecom power supply that converts utility line voltage into DC voltage, can be a solar array, or can be an energy storage device such as a rechargeable battery, a fuel cell, etc. It can be understood that the embodiments of the present application do not limit the type of DC power source. The load 111 is used to represent the power consumed by the circuit coupled to the LLC resonant converter 200, and can be an electrical appliance, a down-converter coupled to the output of the LLC resonant converter 200, etc., which is not limited herein.

[0048] As shown in FIG. 1, the LLC resonant converter 200 can include an inverter circuit 102, a resonant tank 104, a transformer 112, a rectifier 114, and an output filter 116. The inverter circuit 102, the resonant tank 104, the transformer 112, the rectifier 114, and the output filter 116 are coupled to each other and are cascaded between the input DC power source 101 and the load 111.

[0049] The inverter circuit 102 is used to convert the direct current provided by the input DC power source 101 into alternating current (inversion), and can include the primary side switch of a full-bridge resonant converter, or can include the primary side switch of a half-bridge resonant converter and a push-pull resonant converter, etc., which is not limited in detail. The configuration of the inverter circuit 102 will be described in detail below in connection with FIG. 2.

[0050] The resonance tank 104 is configured to provide a resonance component. For example, the resonance tank 104 can include a series resonant inductor, a parallel resonant inductor, and a series resonant capacitor, which is commonly referred to as an LLC resonant converter. In this case, the series resonant inductor, the parallel resonant inductor, and the series resonant capacitor form a resonance process. When the primary-side switches in the inverter circuit 102 operate at a switching frequency that is approximately equal to the resonant frequency of the resonance tank 104, the resonance tank 104 helps to achieve zero-voltage switching (ZVS) for the primary-side switches and zero-current switching (ZCS) for the secondary-side switches in the LLC resonant converter, which greatly reduces the switching power loss in the LLC resonant converter and thus improves the power conversion efficiency of the LLC resonant converter 200.

[0051] The transformer 112 is configured to achieve electrical isolation between the primary side and the secondary side of the LLC resonant converter 200 and to transform the voltage. For example, the transformer 112 can include two sets of windings, including a primary winding (primary-side winding) and a secondary winding (secondary-side winding). Alternatively, the transformer 112 can include a center-tapped secondary winding, i.e., the transformer 112 includes three sets of windings, including a primary winding, a first secondary winding, and a second secondary winding. The structure of the transformer 112 is not limited in the embodiments of the present application.

[0052] The rectifier 114 is configured to convert the received AC bipolar waveform at the output end of the transformer 112 into a unipolar waveform, i.e., to achieve AC-DC conversion. For example, in the above example, when the transformer 112 includes a center-tapped secondary winding, the rectifier 114 can include a pair of switching components, such as a pair of diode combinations. When the transformer 112 includes a single secondary winding, the rectifier 114 can be a full-wave rectifier coupled to the single secondary winding.

[0053] For example, the switching components in the rectifier 114 can be various types of controllable devices, including but not limited to n-type metal oxide semiconductor (NMOS) transistors, metal oxide semiconductor field effect transistor (MOSFET) devices, bipolar junction transistor (BJT) devices, super junction transistor (SJT) devices, insulated gate bipolar transistor (IGBT) devices, etc., without limitation. It can be understood that the detailed operation and structure of the rectifier 114 are well known in the art and are not discussed herein.

[0054] The output filter 116 is used to attenuate the switching ripple of the LLC resonant converter 200. According to the operating principle of the isolated DC-DC converter, the output filter 116 can be an L-C filter composed of an inductor and multiple capacitors, or an output filter composed of capacitors. It can be understood that different output filter configurations are applied to different power converter topologies, and the topology structure of the embodiments of the present application is not limited.

[0055] Based on the above description, FIG. 2 is a structural schematic diagram of an LLC resonant converter provided by an embodiment of the present application. It can be understood that FIG. 2 is a possible hardware topology of the LLC resonant converter 200 shown in FIG. 1, and a full-bridge LLC resonant converter is shown. It can be understood that the LLC resonant converter 200 can have many variations, alternatives and modifications. For example, the LLC resonant converter 200 can be a half-bridge converter and a push-pull converter. The full-bridge LLC resonant converter shown in FIG. 2 is only limited to clearly illustrate the technical solutions of the present application, and is not limited to the topology structure of the LLC resonant converter 200. As shown in FIG. 2:

[0056] The inverter circuit 102 includes full-bridge tubes, which constitute a primary side switching network of the full-bridge resonant converter. Specifically, it includes four switching components, namely, switch Q5, switch Q6, switch Q7 and switch Q8. Among them, switch Q5 and switch Q6 are connected in series, and switch Q7 and switch Q8 are connected in series. The branch in which switch Q5 and switch Q6 are located is connected in parallel with the branch in which switch Q7 and switch Q8 are located. The common node between switch Q5 and switch Q6 is coupled to the first input end T1 of the resonant tank 104, and the common node between switch Q7 and switch Q8 is coupled to the second input end T2 of the resonant tank 104.

[0057] For example, the switches in the above-mentioned inverter circuit 102 can be any type of controllable switch. For example, IGBT device, integrated gate commutated thyristor (IGCT) device, gate turn-off thyristor (GTO) device, junction gate field effect transistor (JFET) device, etc., and the embodiments of the present application do not limit this.

[0058] For example, when the inverter circuit 102 is working, switch Q5 and switch Q8 are turned on at the same time, and switch Q6 and switch Q7 are turned off at the same time. At this time, the current flows from the positive terminal of the power supply VIN, through switch Q5, to the common node between switch Q5 and switch Q6, to the resonant tank 104, to the primary winding of the transformer 112, and finally to the negative terminal of the power supply VIN through switch Q8. At this time, the voltage at the upper end of the transformer 112 is positive. Then, switch Q5 and switch Q8 are turned off at the same time, and switch Q6 and switch Q7 are turned on at the same time. At this time, the current flows from the positive terminal of the power supply VIN, through switch Q7, to the common node between switch Q7 and switch Q8, to the resonant tank 104, to the primary winding of the transformer 112, and finally to the negative terminal of the power supply VIN through switch Q6. At this time, the voltage at the upper end of the transformer 112 is negative. In this way, the process of converting the direct current provided by VIN into alternating current is achieved.

[0059] It should be noted that although FIG. 2 describes four switches Q5, Q6, Q7 and Q8, embodiments of the present application can include other variations, modifications and alternatives. For example, a separate capacitor can be connected in parallel with each switch in the inverter circuit 102, and such a separate capacitor helps to better control the time of the resonance process of the LLC resonant converter 200.

[0060] The resonant tank 104 is composed of a series resonant inductor Lr, a series resonant capacitor Cr1 and a parallel inductor Lm. As shown in FIG. 2, the series resonant inductor Lr and the series resonant capacitor Cr1 are connected in series and coupled to the primary winding of the transformer 112.

[0061] It should be noted that although the series resonant inductor Lr shown in FIG. 2 is a separate component, the series resonant inductor Lr can be replaced by the leakage inductance of the transformer 112, i.e. the leakage inductance (not shown) can act as the series resonant inductor Lr.

[0062] Specifically, the inductance of the series resonant inductor Lr and the parallel inductor Lm and the capacitance of the series resonant capacitor Cr1 determine the resonant frequency corresponding to the resonant tank 104. If the switching frequency of each switch in the inverter circuit 102 is equal to the resonant frequency corresponding to the resonant tank 104, then zero voltage switching ZVS of Q5, Q6, Q7 and Q8 and zero current switching ZCS of the switches in the secondary rectifier can be achieved, which greatly reduces the switching loss and improves the conversion efficiency of the entire LLC resonant converter 200.

[0063] The transformer 112 can be composed of a primary winding and a center-tapped secondary winding. As shown in FIG. 2, the primary winding is coupled to the T3 terminal and the T4 terminal of the resonant tank 104. The secondary winding is coupled to the load 111 through the rectifier 114, wherein the rectifier 114 is composed of switch S1 and switch S2.

[0064] For example, the secondary side of the transformer 112 can be a single winding, and thus the rectifier 114 can be a synchronous rectifier composed of four switching elements. The operation of a synchronous rectifier coupled to a single secondary winding or center-tapped converter secondary is well known to those skilled in the art and will not be discussed herein. It is to be understood that the rectifier can also be configured in other ways, such as a voltage doubler rectifier, a current doubler rectifier, etc., and the embodiments of the present application are not limited in this respect.

[0065] Specifically, the inverter circuit 102 converts the DC power provided by VIN into AC power. The transformer 112 then steps up or steps down the input AC power based on electromagnetic induction. The AC power with a changed voltage value is output through the secondary winding, and then the rectifier 114 converts the AC power into DC power, thereby achieving the purpose of DC-DC conversion.

[0066] FIG. 2 further illustrates an LLC resonant converter 200 including a driver 202. As shown in FIG. 2, the driver 202 is a driving circuit that can generate gate drive signals for the switches (such as Q5, Q6, Q7, Q8) in the inverter circuit 102 and the switches (such as S1 and S2) in the rectifier 114 in the main power circuit (i.e., the circuit corresponding to the LLC resonant converter) to control the turn-on and turn-off of the switches. For example, a single driver 202 can provide gate drive signals to both the primary side switches and the secondary side switches in the main power circuit, or multiple drivers 202 can provide gate drive signals to the primary side switches and the secondary side switches in the main power circuit, respectively, and the embodiments of the present application are not limited in this respect. For example, the driver 202 can also include an isolation device, such as a signal converter, etc. For example, the driver 202 can be a lossless gate drive circuit and a pulse-width modulation (PWM) gate drive circuit, etc., and the embodiments of the present application are not limited in this respect.

[0067] Based on the above description, FIG. 3 is a structural schematic diagram of a driving circuit provided by an embodiment of the present application. It is to be understood that the driving circuit is a possible example of the driver 202 in FIG. 2. As shown in FIG. 3, the driving circuit includes a driving bridge composed of a switch Q1, a switch Q2, a switch Q3, and a switch Q4. Specifically, the switch Q1 and the switch Q2 are coupled between a bias voltage Vdrv and ground, and the switch Q1 and the switch Q2 are connected in series. Similarly, the switch Q3 and the switch Q4 are coupled between the bias voltage Vdrv and ground, and the switch Q3 and the switch Q4 are connected in series.

[0068] For example, the common node between switch Q1 and switch Q2 is G1, which is used to provide gate drive signals for the first high-side switch (e.g., switch Q5 shown in FIG. 2) and the second low-side switch (e.g., switch Q8 shown in FIG. 2) in the inverter circuit 102 of the main power circuit. Specifically, in the example shown in FIG. 2, the common node G1 connects the gates of switch Q5 and switch Q8, and the voltage at point G1 provides gate drive for switch Q5 and switch Q8. Similarly, the common node between switch Q3 and switch Q4 is G2, which is used to provide gate drive signals for the first low-side switch (e.g., switch Q6 shown in FIG. 2) and the second high-side switch (e.g., switch Q7 shown in FIG. 2) in the inverter circuit 102 of the main power circuit. Specifically, in the example shown in FIG. 2, the common node G2 connects the gates of switch Q6 and switch Q7, and the voltage at point G2 provides gate drive for switch Q6 and switch Q7.

[0069] For example, switch Q1, switch Q2, switch Q3, and switch Q4 are implemented by N-channel MOSFETs, P-channel MOSFETs, or any combination thereof. In one example, switch Q1 and switch Q3 can be driven by narrow PWM pulses, i.e., the gate pulse signals (drive) for switch Q1 and switch Q3 can be narrow PWM pulses with a duty cycle of 5% to 25%. Switch Q2 and switch Q4 can be driven by wide PWM pulses, i.e., the gate pulse signals (drive) for switch Q2 and switch Q4 can be wide PWM pulses with a duty cycle of 40% to 60%.

[0070] It is noted that the duty cycle of the gate pulse signals for switch Q1 and switch Q3 can be adjusted. By adjusting the pulse width of the gate pulse signals for switch Q1 and switch Q3, the gate drive period of each switch in the inverter circuit of the main power circuit is changed, which can affect the switching frequency of each switch in the inverter circuit, and thus make the switching frequency of the inverter circuit more closely match the resonant frequency of the resonant cavity.

[0071] In one alternative embodiment, FIG. 4 shows the switching waveforms of the drive circuit according to an embodiment of the present application. As shown in FIG. 4, the horizontal axis is time in microseconds. The first vertical axis Y1 represents the gate pulse signals for switch Q1 and switch Q2 of the drive circuit shown in FIG. 3. The second vertical axis Y2 represents the gate pulse signals for switch Q3 and switch Q4 of the drive circuit shown in FIG. 3. That is, switch Q1, switch Q2, switch Q3, and switch Q4 are turned on and off according to their respective gate pulse signals shown in FIG. 4. It is understood that if switch Q1 is turned on when its gate pulse signal is high and turned off when its gate pulse signal is low. Switch Q2, switch Q3, and switch Q4 operate in a similar manner as switch Q1, and thus are not described again.

[0072] The gate capacitance (gate parasitic capacitance) of the switches in the inverter circuit 102 of the main power circuit and the excitation inductance in the driving circuit also undergo a resonance process. Therefore, if the gate pulse signals of the switches Q1, Q2, Q3 and Q4 are according to the pulse waveforms shown in FIG. 4, the voltage waveforms of the common node G1 of the switches Q1 and Q2 and the common node G2 of the switches Q3 and Q4 are shown in the third vertical axis Y3.

[0073] Specifically, the waveform 1202 is the gate pulse signal of the switch Q3 shown in FIG. 3, the waveform 1204 is the gate pulse signal of the switch Q2 shown in FIG. 3, the waveform 1212 is the gate pulse signal of the switch Q4 shown in FIG. 3, and the waveform 1214 is the gate pulse signal of the switch Q1 shown in FIG. 3.

[0074] Thus, the waveform 1222 is the voltage waveform of the common node G1 shown in FIG. 3, and the waveform 1224 is the voltage waveform of the common node G2 shown in FIG. 3. It can be understood that the voltage of the common node G1 is the gate driving signal provided by the switches Q5 and Q8 in the inverter circuit 102 of the main power circuit, and the voltage of the common node G2 is the gate driving signal provided by the switches Q6 and Q7 in the inverter circuit 102 of the main power circuit. Therefore, the waveform 1222 is the gate driving signal waveform corresponding to the switches Q5 and Q8, and the waveform 1224 is the gate driving signal waveform corresponding to the switches Q6 and Q7. Taking the waveform 1222 as an example, when the waveform is higher than Vth, the switches Q5 and Q8 are turned on, otherwise the switches Q5 and Q8 are turned off. Similarly, when the waveform of the waveform 1224 is higher than Vth, the switches Q6 and Q7 are turned on, otherwise the switches Q6 and Q7 are turned off.

[0075] Referring to FIG. 5, taking the switch Q1 as an example, the waveform 1 is used to indicate the gate pulse signal of the switch Q1. Under normal resonance parameters, the voltage waveform of the common node G1 is shown in the waveform 2. As can be seen from the waveform 2, at t0, the voltage of the common node G1 rises to the threshold voltage of the switches (switches Q5 and Q8) in the inverter circuit 102 of the main power circuit, at which time the switches Q5 and Q8 are turned on. To t3, the voltage of the common node G1 drops to the threshold voltage Vth of the switches (switches Q5 and Q8) in the inverter circuit 102 of the main power circuit, at which time the switches Q5 and Q8 are turned off. Therefore, the on duration of the switches Q5 and Q8 is the duration from t0 to t3. And at t1, the voltage of the common node G1 rises to the bias voltage Vdrv of the driving circuit, and the switch Q1 needs to be turned on at t1 to achieve zero voltage switching (ZVS) of the switch Q1, and the switching loss of the driving circuit is reduced. Exemplarily, the switch Q1 can also be turned on within a very short time after t1, and generally the error of the turn-on time should not be greater than 5% of the switching period.

[0076] Since the gate capacitance and magnetizing inductance of the switches (switches Q5 to Q8) in the inverter circuit 102 of the main power circuit are affected by production process, assembly process, permeability of the driving transformer and dielectric sheet tolerance, etc., the gate capacitance deviation is generated. Thus, the corresponding resonance parameters of the driving circuit are changed with the gate capacitance deviation. If the gate capacitance becomes larger, i.e. the resonance parameter becomes larger, the voltage waveform of the common node G1 is as shown in waveform 3. As can be seen from the waveform 3, the duration of the G1 voltage being higher than the threshold voltage Vth becomes shorter, i.e. the conduction duration of the switches Q5 and Q8 becomes shorter, which affects the switching frequency of the switches Q5 and Q8. Specifically, the switching frequency of the switches Q5 and Q8 becomes higher, which will cause the switching frequency thereof to be inconsistent with the resonance frequency of the resonance tank, and the main power circuit (LLC resonance converter) cannot realize zero-current turn-off of the secondary side switches, thus the switching loss thereof becomes higher and the conversion efficiency becomes lower. Meanwhile, in the driving circuit, the voltage rising rate of the common node G1 becomes slower, and the voltage thereof rises to the bias voltage Vdrv of the driving circuit only at the t2 moment, while the switch Q1 has been turned on before the t2 moment, thus zero-voltage switching ZVS of the switch Q1 is not realized, and the switching loss of the driving circuit will also increase.

[0077] If the gate capacitance becomes smaller, i.e. the resonance parameter becomes smaller, the voltage waveform of the common node G1 is as shown in waveform 4. As can be seen from the waveform 4, in the driving circuit, the voltage rising rate of the common node G1 becomes faster, and the voltage thereof has been resonated to the peak value before the switch Q1 is turned on, thus the body diode corresponding to the switch Q1 is turned on, which increases the reverse conduction loss of the driving circuit. Meanwhile, the switching frequency of the switches Q5 and Q8 becomes lower, which will cause reverse conduction loss and reverse conduction of the main power circuit.

[0078] It can be understood that the case of the switch Q3 and the common node G2 is completely similar to the case of the switch Q1 and the common node G1 described above. The gate capacitance deviation of the switches Q6 and Q7 in the inverter circuit 102 also affects the resonance condition at the common node G12, and further affects the loss of the driving circuit and the main power circuit, which will not be described herein.

[0079] Based on the above description, it can be known that the gate capacitance deviation of the switches in the main power circuit will affect the resonance period of the driving bridge arm midpoint, and further affect the switching frequency of the switches in the main power circuit. This will cause the problem that the switching frequency of the switches in the main power circuit is inconsistent with the resonance frequency of the resonance tank. Thus, the LLC resonance converter will generate switching power loss, which causes the efficiency of the LLC resonance converter to be inconsistent. Therefore, how to ensure the consistency of the conversion efficiency of the LLC resonance converter becomes a problem to be solved urgently.

[0080] Based on the above description, the embodiment of the present application provides a driving circuit for an LLC resonant converter. The switching frequency of each switch in the main power circuit is determined by detecting the voltage of the driving bridge arm midpoint. Then the switching frequency of each switch in the main power circuit is restored to the resonant frequency of the resonant cavity in the main power circuit by adjusting the gate pulse signal of each driving switch in the driving bridge according to the switching frequency of each switch in the main power circuit, so as to ensure the efficiency consistency of the LLC resonant converter, and further improve the conversion efficiency of the LLC resonant converter. Specifically as follows:

[0081] Fig. 6 is a structural schematic diagram of a driving circuit for an LLC resonant converter provided by the embodiment of the present application. As shown in Fig. 6, the driving circuit comprises a driving signal generation circuit 601, a driving detection circuit 602, a power driving circuit 603 and an auxiliary power supply 604.

[0082] Among them, the structure of the power driving circuit 603 please refer to the structure shown in Fig. 3. Specifically, the power driving circuit 603 comprises a driving bridge, wherein the switch Q1 and the switch Q2 are connected in series and coupled between the bias voltage and the ground. The common node G1 between the switch Q1 and the switch Q2 is coupled to the inverter circuit 102 of the LLC resonant converter shown in Fig. 2, and provides a gate drive signal for the switch Q5 and the switch Q8 in the inverter circuit 102. While the switch Q3 and the switch Q4 are connected in series and coupled between the bias voltage and the ground. The common node G2 between the switch Q3 and the switch Q4 is coupled to the inverter circuit 102 of the LLC resonant converter shown in Fig. 2, and provides a gate drive signal for the switch Q6 and the switch Q7 in the inverter circuit 102.

[0083] Among them, the driving detection circuit 602 is used for detecting the voltage at the common node G1 and the common node G2. Specifically, the driving detection circuit 602 judges whether the voltage at the common node G1 or the common node G2 is greater than or less than the threshold voltage Vth corresponding to the plurality of switches in the inverter circuit 102 (i.e. the threshold voltage of the switch Q5, Q6, Q7, Q8), and needs to output an indication signal to the driving signal generation circuit 601 for indicating whether the voltage at the common node G1 or the common node G2 is greater than or less than the threshold voltage Vth;

[0084] And the driving signal generation circuit 601 is used for receiving the indication signal sent by the driving detection circuit 602, and adjusting the gate pulse signal corresponding to the switch Q1 or the switch Q3 in the driving bridge according to the indication signal. The direction of adjustment is that the frequency of the indication signal received by the driving signal generation circuit 601 is equal to the corresponding resonant frequency of the LLC resonant converter (i.e. the main power circuit).

[0085] Finally, the auxiliary power supply 604 is used to provide the bias voltage for the power driving circuit 603.

[0086] The working principle of the above driving circuit is described as follows:

[0087] Taking the common node G1 as an example, the driving detection circuit 602 detects whether the voltage at the common node G1 is greater than or less than the threshold voltage Vth, and issues an indication signal if it is greater, or issues another indication signal if it is less. It can be understood that when the first indication signal is issued, the switches Q5 and Q8 in the main power circuit start to conduct, and when the second indication signal is issued, the switches Q5 and Q8 in the main power circuit start to close. In this way, the driving signal generation circuit 601 can determine the conduction duration of the switches Q5 and Q8 in the main power circuit according to the receiving time of the two indication signals, so as to obtain the corresponding switching frequency of the switches Q5 and Q8. Then, the driving signal generation circuit 601 can adjust the gate pulse signal of the switch Q1 in the power driving circuit 603 according to the switching frequency of the switches Q5 and Q8, so as to affect the conduction time and duration of the switch Q1, and further adjust the corresponding switching frequency of the switches Q5 and Q8, so as to finally restore the corresponding switching frequency of the switches Q5 and Q8 to equal the corresponding resonant frequency of the main power circuit. In this way, the efficiency consistency of the LLC resonant converter can be ensured, and the conversion efficiency of the LLC resonant converter can be improved.

[0088] Similarly, the driving detection circuit 602 detects whether the voltage at the common node G2 is greater than or less than the threshold voltage Vth, and issues an indication signal if it is greater, which is used to indicate that the switches Q6 and Q7 start to conduct. If it is less, another indication signal is issued, which is used to indicate that the switches Q6 and Q7 in the main power circuit start to close. In this way, the driving signal generation circuit 601 can determine the conduction duration of the switches Q6 and Q7 in the main power circuit according to the receiving time of the two indication signals, so as to obtain the corresponding switching frequency of the switches Q6 and Q7. Then, the driving signal generation circuit 601 can adjust the gate pulse signal of the switch Q3 in the power driving circuit 603 according to the switching frequency of the switches Q6 and Q7, so as to affect the conduction time and duration of the switch Q3, and further adjust the corresponding switching frequency of the switches Q6 and Q7, so as to finally restore the corresponding switching frequency of the switches Q6 and Q7 to equal the corresponding resonant frequency of the main power circuit. In this way, the efficiency consistency of the LLC resonant converter can be ensured, and the conversion efficiency of the LLC resonant converter can be improved.

[0089] Based on the above description, the exemplary drive detection circuit 602 can include a first comparator A1 and a second comparator A2. Wherein A1 corresponds to the common node G1, the first end is used to input the voltage value corresponding to the common node G1, and the second end is used to input the threshold voltage Vth. And A2 corresponds to the common node G2, the first end is used to input the voltage value corresponding to the common node G2, and the second end is used to input the threshold voltage Vth.

[0090] Specifically, when the voltage value corresponding to the common node G1 is greater than the threshold voltage Vth, A1 outputs a first indication signal, and when the voltage value corresponding to the common node G1 is less than the threshold voltage Vth, A1 outputs a second indication signal. Exemplarily, the first indication signal can be a high level signal, and the second indication signal can be a low level signal. Of course, the first indication signal can also be a low level signal, and the second indication signal can be a high level signal, and the embodiments of the present application do not limit this.

[0091] When the voltage value corresponding to the common node G2 is greater than the threshold voltage Vth, A2 outputs a third indication signal, and when the voltage value corresponding to the common node G2 is less than the threshold voltage Vth, A2 outputs a fourth indication signal. Exemplarily, the third indication signal can be a high level signal, and the fourth indication signal can be a low level signal. Of course, the third indication signal can also be a low level signal, and the fourth indication signal can be a high level signal, and the embodiments of the present application do not limit this.

[0092] It can be understood that the drive detection circuit 602 is composed of a comparator, and its circuit structure is simple and low in cost. Of course, the drive detection circuit 602 can also be composed of other circuit elements, exemplarily, it can be composed of an ADC and a digital comparator, the ADC is used to sample and convert the voltage signal into a digital signal, and then the data comparator compares the size of the digital signal to output the indication signal.

[0093] Based on the above driving detection circuit 602, the driving signal generation circuit 601 determines the first interval duration according to the time of the first indication signal and the second indication signal output by the first comparator Al. It can be understood that, in the first interval duration, the voltage value corresponding to the common node Gl is greater than the threshold voltage Vth, so the switches Q5 and Q8 in the inverter circuit 102 of the main power circuit are turned on, that is, the first interval duration is the on duration of the switches Q5 and Q8, so that the switching frequency (the first frequency value) of the switches Q5 and Q8 can be obtained based on the on duration. Then, it is judged which case described in the embodiment shown in FIG. 5 based on the first frequency value. For example, if the switching frequency is greater than the resonant frequency of the main power circuit, then the voltage waveform corresponding to the common node Gl is shown as waveform 2, so it is necessary to increase the width of the pulse in the gate pulse signal corresponding to the switch Q1, that is, to increase the on duration of the switch Q1. In this way, the falling time of the voltage corresponding to the common node Gl is delayed, the on duration of the switches Q5 and Q8 is lengthened, the switching frequency thereof is reduced, and the resonant frequency of the main power circuit is restored to ensure the efficiency consistency of the main power circuit. For example, if the switching frequency is less than the resonant frequency of the main power circuit, then the voltage waveform corresponding to the common node Gl is shown as waveform 4, so it is necessary to reduce the width of the pulse in the gate pulse signal corresponding to the switch Q1, that is, to reduce the on duration of the switch Q1. In this way, the falling time of the voltage corresponding to the common node Gl is advanced, the on duration of the switches Q5 and Q8 is shortened, the switching frequency thereof is increased, and the resonant frequency of the main power circuit is restored to ensure the efficiency consistency of the main power circuit.

[0094] Similarly, the driving signal generating circuit 601 determines the second interval duration according to the time points of the third indication signal and the fourth indication signal output by the second comparator A2. It can be understood that, in the second interval duration, the voltage value corresponding to the common node G2 is greater than the threshold voltage Vth, and therefore the switches Q6 and Q7 in the inverter circuit 102 of the main power circuit are turned on, i.e., the second interval duration is the on duration of the switches Q6 and Q7, so that the switching frequency (the second frequency value) of the switches Q6 and Q7 can be obtained based on the on duration. Then, it is determined which case described in the embodiment shown in FIG. 5 based on the second frequency value. For example, if the switching frequency is greater than the resonant frequency of the main power circuit, then the voltage waveform corresponding to the common node G2 is shown as the waveform 2, and it is necessary to increase the width of the pulse in the gate pulse signal corresponding to the switch Q3, i.e., to increase the on duration of the switch Q3. In this way, the falling time of the voltage corresponding to the common node G2 is delayed, the on duration of the switches Q6 and Q7 is lengthened, the switching frequency of the switches Q6 and Q7 is reduced, and the resonant frequency of the main power circuit is restored to ensure the efficiency consistency of the main power circuit. For example, if the switching frequency is less than the resonant frequency of the main power circuit, then the voltage waveform corresponding to the common node G2 is shown as the waveform 4, and it is necessary to decrease the width of the pulse in the gate pulse signal corresponding to the switch Q3, i.e., to decrease the on duration of the switch Q3. In this way, the falling time of the voltage corresponding to the common node G2 is advanced, the on duration of the switches Q6 and Q7 is shortened, the switching frequency of the switches Q6 and Q7 is increased, and the resonant frequency of the main power circuit is restored to ensure the efficiency consistency of the main power circuit.

[0095] For example, the driving detection circuit 602 can also be used to compare the voltage value corresponding to the common node G1 or the common node G2 with the bias voltage Vdrv. It can be understood that, if the switch Q1 is turned on when the voltage of the common node G1 resonates to the bias voltage Vdrv, zero voltage switching ZVS can be achieved, and similarly, if the switch Q3 is turned on when the voltage of the common node G2 resonates to the bias voltage Vdrv, zero voltage switching ZVS can also be achieved. In this way, the switching loss of the driving detection circuit 602 can be reduced, and the driving performance is further improved. It can be understood that, the on time of the switch Q1 or the switch Q3 should be before or after the time point at which the voltage of the common node G1 or the common node G2 resonates to the bias voltage Vdrv, so as to avoid the conduction of the body diode of the switch. For example, the error of the on time should be between 1% and 3% of the switching period.

[0096] Specifically, the first end of the first comparator A1 is configured to input the voltage value corresponding to the common node G1, and the second end is configured to input the bias voltage Vdrv. The first end of the second comparator A2 is configured to input the voltage value corresponding to the common node G2, and the second end is configured to input the bias voltage Vdrv. When the first comparator determines that the voltage value corresponding to the common node G1 is equal to the bias voltage Vdrv, the fifth indication signal is output to the drive signal generation circuit 601, so that the drive signal generation circuit 601 adjusts the starting time of the pulse in the gate pulse signal corresponding to the switch Q1 to the receiving time of the fifth indication signal, so as to realize the zero voltage switching ZVS of the switch Q1. Similarly, when the second comparator determines that the voltage value corresponding to the common node G2 is equal to the bias voltage Vdrv, the sixth indication signal is output to the drive signal generation circuit 601, so that the drive signal generation circuit 601 adjusts the starting time of the pulse in the gate pulse signal corresponding to the switch Q3 to the receiving time of the sixth indication signal, so as to realize the zero voltage switching ZVS of the switch Q3.

[0097] It can be understood that the drive signal generation circuit 601 cannot infinitely adjust the pulse width of the gate pulse signal corresponding to the switch Q1 or the switch Q3. When the pulse width reaches a certain threshold, the drive signal generation circuit 601 can also realize the zero voltage switching ZVS of the switches in the drive circuit by adjusting the bias voltage Vdrv through the auxiliary power supply 604.

[0098] For example, when the first frequency value corresponding to the common node G1 is greater than the resonant frequency corresponding to the main power circuit, the drive signal generation circuit 601 increases the pulse width of the gate pulse signal corresponding to the switch Q1, and when the duty cycle of the gate pulse signal corresponding to the switch Q1 reaches a first preset duty cycle, the switching frequency corresponding to the main power circuit cannot be adjusted. At this time, the zero voltage switching ZVS of the switch Q1 (the drive tube) in the drive circuit can be realized by reducing the bias voltage Vdrv, so as to further reduce the drive loss. For example, the first preset duty cycle is generally 80%, that is, the duty cycle of the gate pulse signal corresponding to the switch Q1 cannot exceed 80%.

[0099] When the first frequency value corresponding to the common node G1 is less than the resonant frequency corresponding to the main power circuit, the drive signal generation circuit 601 reduces the pulse width of the gate pulse signal corresponding to the switch Q1, and when the duty cycle of the gate pulse signal corresponding to the switch Q1 reaches a second preset duty cycle, the switching frequency corresponding to the main power circuit cannot be adjusted. At this time, the zero voltage switching ZVS of the switch Q1 (the drive tube) in the drive circuit can be realized by increasing the bias voltage Vdrv, so as to further reduce the drive loss. For example, the second preset duty cycle is generally 5%, that is, the duty cycle of the gate pulse signal corresponding to the switch Q1 cannot be less than 5%.

[0100] Similarly, when the first frequency value corresponding to the common node G2 is greater than the resonant frequency corresponding to the main power circuit, the drive signal generation circuit 601 increases the pulse width of the gate pulse signal corresponding to the switch Q3, and when the duty cycle of the gate pulse signal corresponding to the switch Q3 reaches the first preset duty cycle, the switching frequency corresponding to the main power circuit cannot be adjusted any more. At this time, the zero voltage switching ZVS of the switch Q3 (driving tube) in the driving circuit can be realized by reducing the bias voltage Vdrv, so as to further reduce the driving loss. For example, the first preset duty cycle is generally 80%, that is, the duty cycle of the gate pulse signal corresponding to the switch Q1 cannot exceed 80%.

[0101] When the first frequency value corresponding to the common node G2 is less than the resonant frequency corresponding to the main power circuit, the drive signal generation circuit 601 reduces the pulse width of the gate pulse signal corresponding to the switch Q3, and when the duty cycle of the gate pulse signal corresponding to the switch Q3 reaches the second preset duty cycle, the switching frequency corresponding to the main power circuit cannot be adjusted any more. At this time, the zero voltage switching ZVS of the switch Q3 (driving tube) in the driving circuit can be realized by increasing the bias voltage Vdrv, so as to further reduce the driving loss. For example, the second preset duty cycle is generally 5%, that is, the duty cycle of the gate pulse signal corresponding to the switch Q1 cannot be less than 5%.

[0102] Based on the above description, the embodiment of the present application further provides a direct current converter, which comprises an LLC resonant converter and a driving circuit provided by the embodiment shown in Fig. 6.

[0103] The structure of the direct current converter can refer to the structure of the LLC resonant converter shown in Fig. 1, and the working principle can also refer to the description of the example shown in Fig. 1, which will not be repeated here.

[0104] The driving circuit is used to provide a gate driving signal for the switch in the inverter circuit of the LLC resonant converter. The specific driving process can refer to the description of the embodiment shown in Fig. 6, which will not be repeated here.

[0105] Fig. 7 is a structural schematic diagram of an integrated power supply module provided by the embodiment of the present application. As shown in Fig. 7, the integrated power supply module comprises a power supply module 701, a control module 702 and a power supply conversion module 703.

[0106] The power supply module 701 and the control module 702 are connected with the power supply conversion module 703 respectively. The control module 702 is used to control the start and shutdown of the power supply conversion module 703, and the power supply module 701 is used to provide direct current.

[0107] The power supply conversion module 703 is used to perform DC-DC conversion on the direct current output by the power supply module 701.

[0108] The power conversion module 703 includes an LLC resonant converter and a driving circuit as provided in the embodiment of FIG. 6. Specifically, the LLC resonant converter includes an inverter circuit, and the driving circuit is configured to provide gate drive signals for switches in the inverter circuit.

[0109] FIG. 8 is a structural schematic diagram of an electronic device 1800 according to an embodiment of the present application. The electronic device 1800 can include one or more central processing units (CPUs) 1801 and a memory 1805 in which one or more application programs or data are stored.

[0110] The memory 1805 can be volatile memory or persistent memory. The programs stored in the memory 1805 can include one or more modules, each of which can include a series of instructions for operating the management server. Further, the central processing unit 1801 can be configured to communicate with the memory 1805 and execute the series of instructions in the memory 1805 on the bus controller 1800.

[0111] The central processing unit 1801 is configured to execute the computer programs in the memory 1805.

[0112] The first device 1800 can further include one or more power modules 1802, one or more wired or wireless network interfaces 1803, one or more input / output interfaces 1804, and / or one or more operating systems, such as Windows ServerTM, Mac OS XTM, UnixTM, LinuxTM, FreeBSDTM, etc.

[0113] The power module 1802 can include a power supply and a DC converter.

[0114] The DC converter can be connected to the power supply and convert the voltage output by the power supply to the supply voltage of the load. The power supply can be, but is not limited to, a battery or other DC power supply.

[0115] The DC converter includes an LLC resonant converter and a driving circuit as provided in the embodiment of FIG. 6. The LLC resonant converter includes an inverter circuit, and the driving circuit is configured to provide gate drive signals for switches in the inverter circuit.

[0116] Although the application has been described in connection with various embodiments, it will be understood that the application disclosed herein is capable of further modifications. In the claims, the word "comprising" does not exclude other components or steps not mentioned in the claims. The word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. The use of the expression "at least one" preceding an element does not exclude the presence of a plurality of such elements. The use of the expression "one of' preceding the elements in a list of elements does not exclude the presence of at least one other such element. The use of the expression "at least one", when used to define a plurality of elements, does not exclude the presence of at least one additional such element. It is further noted that claims, or a portion thereof, can be directed to yet another alternative embodiment of the application. Furthermore, some of the features of the described object, can each be defined as in its own independent claim. In addition, some of the features of the described object can be combined with each other and further features can be omitted in other embodiments or additional features can be added to the described object. Still further, features of the described object can be applied to other embodiments of the described object.

Claims

1. A drive circuit for generating gate drive signals for a plurality of switches of an inductor-inductor-capacitor (LLC) resonant converter, the resonant converter comprising an inverter circuit, the inverter circuit comprising a first high-side switch, a first low-side switch, a second high-side switch, and a second low-side switch; characterized in that, The drive circuit comprises: a drive signal generation circuit, a drive detection circuit, a power drive circuit and an auxiliary power supply; The power drive circuit comprises a drive bridge coupled between a bias voltage and a ground, the drive bridge is used to be coupled to the LLC resonant converter, and the drive bridge comprises: a switch Q1 and a switch Q2 coupled in series and between the bias voltage and the ground; a common node G1 between the switch Q1 and the switch Q2 is used to provide a gate drive signal for the first high-side switch and the second low-side switch; a switch Q3 and a switch Q4 coupled in series and between the bias voltage and the ground; a common node G2 between the switch Q3 and the switch Q4 is used to provide a gate drive signal for the first low-side switch and the second high-side switch; The drive detection circuit is used to detect whether the voltage at the common node G1 or the common node G2 is greater than or less than a threshold voltage Vth corresponding to a plurality of switches in the inverter circuit, and output an indication signal indicating whether the voltage at the common node G1 or the common node G2 is greater than or less than the threshold voltage Vth. The drive signal generation circuit is used to receive the indication signal, and adjust the gate pulse signal corresponding to the switch Q1 or the switch Q3 in the drive bridge according to the indication signal; so that the frequency at which the drive signal generation circuit receives the indication signal is equal to the resonant frequency corresponding to the resonant converter; the common node G1 corresponds to the switch Q1, and the common node G2 corresponds to the switch Q3; The auxiliary power supply is used to provide the bias voltage for the power drive module.

2. The drive circuit according to claim 1, characterized in that, The drive detection circuit comprises a first comparator and a second comparator; The first end of the first comparator is used to input the voltage value corresponding to the common node G1, and the second end of the first comparator is used to input the threshold voltage Vth; the first end of the second comparator is used to input the voltage value corresponding to the common node G2, and the second end of the second comparator is used to input the threshold voltage Vth; The first comparator is used to output a first indication signal when the voltage value corresponding to the common node G1 is greater than the threshold voltage Vth; output a second indication signal when the voltage value corresponding to the common node G1 is less than the threshold voltage Vth; The second comparator is used to output a third indication signal when the voltage value corresponding to the common node G2 is greater than the threshold voltage Vth, and output a fourth indication signal when the voltage value corresponding to the common node G2 is less than the threshold voltage Vth.

3. The drive circuit according to claim 2, characterized in that, The drive signal generation circuit is specifically used to: determine a first interval duration according to the receiving time of the first indication signal and the second indication signal, and determine a first frequency value according to the first interval duration; adjust the gate pulse signal corresponding to the switch Q1 according to the first frequency value, so that the first frequency value is equal to the resonant frequency corresponding to the LLC resonant converter.

4. The drive circuit according to claim 2 or 3, characterized in that, The drive signal generation circuit is specifically used to: determine a second interval duration according to the receiving time of the third indication signal and the fourth indication signal; and determine a second frequency value according to the second interval duration; adjust the gate pulse signal corresponding to the switch Q3 according to the second frequency value, so that the second frequency value is equal to the resonant frequency corresponding to the LLC resonant converter.

5. The drive circuit according to claim 4, characterized in that, The driving signal generation circuit is specifically configured to: when the first frequency value or the second frequency value is less than the resonant frequency corresponding to the LLC resonant converter, reduce the width of the pulse in the gate pulse signal corresponding to the switch Q1 or the switch Q3; when the first frequency value or the second frequency value is greater than the resonant frequency corresponding to the LLC resonant converter, increase the width of the pulse in the gate pulse signal corresponding to the switch Q1 or the switch Q3.

6. The driving circuit according to any one of claims 2 to 5, wherein: the second end of the first comparator is further configured to input the bias voltage; and the second end of the second comparator is further configured to input the bias voltage. The first comparator is configured to output a fifth indication signal to the driving signal generation circuit when the voltage value corresponding to the common node G1 is equal to the bias voltage. The second comparator is configured to output a sixth indication signal to the driving signal generation circuit when the voltage value corresponding to the common node G2 is equal to the bias voltage.

7. The drive circuit according to claim 6, characterized in that, The driving signal generation circuit is further configured to: adjust the starting time of the pulse in the gate pulse signal corresponding to the switch Q1 to the receiving time of the fifth indication signal; or adjust the starting time of the pulse in the gate pulse signal corresponding to the switch Q3 to the receiving time of the sixth indication signal.

8. The drive circuit according to any one of claims 5 to 7, characterized in that, The driving signal generation circuit is further configured to control the auxiliary power supply to adjust the bias voltage according to the indication signal.

9. The drive circuit according to claim 8, characterized in that, The driving signal generation circuit is specifically configured to: when the first frequency value or the second frequency value is greater than the resonant frequency corresponding to the LLC resonant converter, and the duty cycle of the gate pulse signal corresponding to the switch Q1 or the switch Q3 reaches a first preset duty cycle, reduce the size of the bias voltage; when the first frequency value or the second frequency value is less than the resonant frequency corresponding to the LLC resonant converter, and the duty cycle of the gate pulse signal corresponding to the switch Q1 or the switch Q3 reaches a second preset duty cycle, increase the size of the bias voltage; the first preset duty cycle is less than the second preset duty cycle.

10. A direct current converter characterized by The direct current converter comprises an LLC resonant converter and the driving circuit according to any one of claims 1 to 9. The LLC resonant converter comprises an inverter circuit. The driving circuit is configured to provide a gate driving signal for a switch in the inverter circuit.

11. An integrated power module, characterized by The integrated power supply module comprises a power supply module, a control module and a power supply conversion module. The power supply module is connected with the power supply conversion module. The control module is configured to control the start and shutdown of the power supply conversion module. The integrated power supply module comprises a power supply module, a control module and a power supply conversion module. The power supply module is connected with the power supply conversion module. The control module is configured to control the start and shutdown of the power supply conversion module. The power conversion module is configured to convert the direct current output by the power supply module. The power conversion module comprises an inductor-inductor-capacitor (LLC) resonant converter and the drive circuit according to any one of claims 1 to 9. The drive circuit is configured to provide a gate drive signal for a switch in an inverter circuit in the LLC resonant converter.

12. An electronic device, comprising: The electronic device comprises a power supply and a direct current converter; The direct current converter is connected to the power supply, and the direct current converter is configured to convert a voltage output by the power supply into power supply for a load; The direct current converter comprises an inductor-inductor-capacitor (LLC) resonant converter and the drive circuit according to any one of claims 1 to 9. The drive circuit is configured to provide a gate drive signal for a switch in an inverter circuit in the LLC resonant converter.

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