LLC resonant converter

Abstract

The utility model relates to an LLC resonant converter which comprises a commercial power conversion circuit, a control circuit, a high-voltage resonant controller circuit, a drive circuit, an LLC circuit and a secondary rectification filter circuit. The control circuit, the high-voltage resonance controller circuit, the drive circuit, the LLC circuit and the secondary rectification filter circuit are connected in sequence, and the control circuit is connected with the secondary rectification filter circuit and used for receiving sampling values of the secondary rectification filter circuit and outputting mode control signals corresponding to different working modes to the high-voltage resonance controller circuit according to the sampling values. The high-voltage resonance controller circuit outputs different PWM signals to the drive circuit according to mode control signals, outputs a first PWM signal in a normal mode and outputs a second PWM signal and a modulation wave of a high-frequency first signal in a burst mode, the drive circuit drives the LLC circuit to work according to the PWM signals, the secondary rectification filter circuit outputs high-frequency voltage, and output ripples are reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of converters, in particular to an LLC resonant converter. Background Art

[0002] At present, the working modes of LLC resonant converter include: normal mode (ResonantMode) within the load range and burst mode (BurstMode) at light load or no load. In normal mode, the first PWM signal driving the LLC front-end power tube operates at about 100KHz, with a duty cycle of 50%, and the DC voltage applied to the primary of the transformer alternates at a first fixed frequency. In burst mode, in order to reduce power consumption, the second PWM signal driving the LLC front-end power tube is applied in an interval manner. When the second PWM signal is applied in the previous period, the transformer has output, and the output voltage of the LLC resonant converter increases. In the next period, the second PWM signal is not applied, and the LLC The output voltage of the C resonant converter is zero, and the time when the second PWM signal is not applied is automatically controlled by the LLC resonant converter through a loop, and the second PWM signal is turned off to achieve this, that is, in the burst mode, it works in a hiccup mode to control the second PWM signal to be output or not, the second frequency of the second PWM signal is about 300KHz, and the duty cycle is 50%. The second PWM signal is output or not output as the first signal, that is, the second PWM signal is modulated by the first signal. At present, the frequency of the first signal is from 0 to tens of Hz. Due to the low frequency of the first signal, the output voltage of the secondary of the transformer generates relatively large ripples in the burst mode, and there will be a large low-frequency pulse current when it is lightly loaded.

[0003] Specifically, in the LLC resonant converter, a high-voltage resonant controller circuit is used to determine the operating mode and PWM signal output. A new high-voltage resonant controller such as L6599 has a typical timing diagram as shown below: Figure 1 As shown, in burst mode, the STBY signal is between 1.24V and 1.29V, and there is no second PWM signal output when the voltage rises from 1.24V to 1.29V. At this time, the PFC_STOP signal is at a low level. The second PWM signal includes the LVG signal and the HVG signal. When the voltage drops from 1.29V to 1.24V, there is a second PWM signal output, and the PFC_STOP signal is at a high level.

[0004] Therefore, how to reduce both power consumption and ripple in burst mode is an urgent problem to be solved. Utility Model Content

[0005] The utility model aims to provide an LLC resonant converter. In burst mode, L6599 is used as a high-voltage resonant controller chip, and a STBY signal pin of the chip is set to perform high-frequency conversion between a first voltage and a second voltage, thereby increasing the frequency of applying a second PWM signal and not applying the second PWM signal, changing the low-frequency output in burst mode to a high-frequency output, increasing the frequency of the output voltage, reducing ripple, and achieving the purpose of increasing the frequency of the output voltage.

[0006] The above utility model object of the utility model is achieved through the following technical solutions:

[0007] An LLC resonant converter comprises a mains conversion circuit, a control circuit, a high-voltage resonant controller circuit, a drive circuit, an LLC circuit and a secondary rectifier filter circuit. The mains conversion circuit is used to convert the mains alternating current into direct current to provide electric energy to the converter. The control circuit, the high-voltage resonant controller circuit, the drive circuit, the LLC circuit and the secondary rectifier filter circuit are connected in sequence. The control circuit is also connected to the secondary rectifier filter circuit and is used to receive sampling values ​​of the secondary rectifier filter circuit and output mode control signals corresponding to different working modes to the high-voltage resonant controller circuit according to the sampling values. The high-voltage resonant controller circuit is used to output different PWM signals to the drive circuit according to the mode control signal. In the normal mode, the first PWM signal is output to the drive circuit. In the burst mode, the second PWM signal and the modulation wave of the high-frequency first signal are output to the drive circuit. The drive circuit drives the LLC circuit to work according to the PWM signal and outputs a high-frequency stable voltage after passing through the secondary rectifier filter circuit.

[0008] The utility model is further configured as follows: the control circuit includes a main control circuit, a voltage and current operation circuit and an isolation circuit connected in sequence, the main control circuit is used to output a current reference analog quantity and a voltage reference analog quantity to a comparison circuit according to sampling parameters of the converter, the comparison circuit compares the output voltage sampling value with the voltage reference analog quantity, compares the current sampling value with the current reference analog quantity, outputs a first comparison signal to the isolation circuit, and outputs a mode control signal through the isolation circuit.

[0009] The utility model is further configured as follows: the main control circuit includes an MCU and a conversion circuit that are interconnected, the MCU outputs a voltage reference signal and a current reference signal according to sampling parameters, and the conversion circuit is used to convert the voltage reference signal into a voltage reference analog quantity and convert the current reference signal into a current analog adjustment value.

[0010] The utility model is further configured as follows: the conversion circuit includes a voltage reference conversion circuit and a current reference conversion circuit; the current reference conversion circuit includes a first integration circuit, a first initial value setting circuit, a first conversion filter circuit, and a current control circuit connected in sequence; the first integration circuit is used to integrate the current reference signal; the first initial value setting circuit is used to superimpose the integration result with the first initial value to obtain a current reference analog quantity Iref; the first conversion filter circuit filters the current reference analog quantity; the current reference analog quantity is subjected to voltage division to obtain a current analog adjustment value; the current control circuit is used to control the current reference analog quantity according to the current reference signal, the temperature signal and the output voltage, and to control the current analog adjustment value according to the output voltage.

[0011] The utility model is further configured as follows: the current control circuit includes a control subcircuit, a temperature control subcircuit and a voltage control subcircuit; the control subcircuit includes a second switch circuit for controlling the current reference analog quantity Iref according to a current reference signal; the temperature control subcircuit includes a third switch circuit for controlling the current reference analog quantity Iref according to temperature changes; the voltage control subcircuit includes a fourth switch circuit for controlling the current analog adjustment value Iref / a according to the output voltage.

[0012] The utility model is further configured as follows: the voltage-current operation circuit comprises a voltage operation circuit and a current operation circuit, the input of the voltage operation circuit is connected to the output end and the output voltage sampling end of the voltage reference conversion circuit in the main control circuit, and its output is connected to the input end of the isolation circuit; the input of the current operation circuit is connected to the output end and the output current sampling end of the current reference conversion circuit in the main control circuit, and its output is connected to the input end of the isolation circuit and the main control circuit.

[0013] The utility model is further configured as follows: the voltage operation circuit includes a first comparison sub-circuit, the first comparison sub-circuit includes a first operational amplifier, the positive input end of the first comparison sub-circuit is connected to the output end of the voltage reference conversion circuit in the main control circuit, and the positive input end of the first comparison sub-circuit is connected to the output voltage sampling end.

[0014] The utility model is further configured as follows: the current operation circuit includes an amplifier circuit and a second comparison sub-circuit connected in sequence, the amplifier circuit includes a second operational amplifier, the input end of the amplifier circuit is connected to the output current sampling end, and its output end is connected to an input end of the second comparison sub-circuit and the main control circuit, the other input end of the second comparison sub-circuit is connected to the output end of the current control circuit in the main control circuit, and its output is connected to the input end of the isolation circuit.

[0015] The utility model is further configured as follows: the high-voltage resonance controller circuit includes a high-voltage resonance controller chip, a first level setting circuit and a second level setting circuit; the high-voltage resonance controller chip is connected to the LLC circuit, the first level setting circuit and the second level setting circuit; the input of the first level setting circuit is connected to the control circuit and the high-voltage resonance controller chip, and is used to control the output of the first level setting circuit according to a mode control signal of the control circuit; the input and output of the second level setting circuit are both connected to the high-voltage resonance controller chip, and are used to control the output of the second level setting circuit according to an output signal of the high-voltage resonance controller chip; when the high-voltage resonance controller chip is in burst mode, the frequency of the first signal is controlled according to the first level setting circuit and the output of the first level setting circuit, and a modulated wave of the first signal and the second PWM signal is output to the drive circuit.

[0016] The utility model is further configured as follows: the high-voltage resonant controller chip includes L6599, an input end of the first level setting circuit is connected to the mode signal output end of the control circuit, the other input end is connected to the Rfmin signal pin of the high-voltage resonant controller chip, and its output end is connected to the STBY signal pin of the high-voltage resonant controller chip, and is used to set a first level for the STBY signal pin according to the mode signal, and the input end of the second level setting circuit is connected to the PFC_STOP signal pin of the high-voltage resonant controller chip, and its output end is connected to the STBY signal pin of the high-voltage resonant controller chip, and is used to set a second level for the STBY signal pin in burst mode.

[0017] The utility model is further configured as follows: the first level setting circuit includes an RC circuit, a resistor and capacitor connection point of the RC circuit is connected to the control circuit, the resistor includes a series resistor combination, a connection point of the series resistor is connected to the STBY signal pin, and the input end of the RC circuit is connected to the Rfmin signal pin.

[0018] The utility model is further configured as follows: the second level setting circuit includes a fifth switch circuit, a voltage stabilizing circuit, a voltage divider circuit and a limiting circuit connected in sequence, the control end of the fifth switch circuit is connected to the PFC_STOP signal pin, and its output end is connected to the voltage stabilizing circuit, the voltage divider circuit is used to divide the output of the voltage stabilizing circuit, the limiting circuit limits the voltage division result, and the output of the limiting circuit is connected to the STBY signal pin.

[0019] The utility model is further configured as follows: the voltage stabilizing circuit comprises a voltage stabilizing chip for stabilizing the power supply voltage at a set value.

[0020] Compared with the prior art, the beneficial technical effects of this application are:

[0021] 1. The present application increases the frequency of applying the second PWM signal and not applying the second PWM signal, thereby increasing the switching frequency between voltage output and no voltage output, thereby ensuring the stability of the output voltage and reducing the output ripple;

[0022] 2. Furthermore, the present application sets a first level setting circuit and a second level setting circuit at the STBY signal pin of the high-voltage resonant controller, so that the STBY signal pin switches between the first level and the second level in a high-frequency manner, thereby increasing the frequency of the drive output and reducing the output ripple;

[0023] 3. Furthermore, the first level setting circuit and the second level setting circuit of the present application are controlled by corresponding pins of the high-voltage resonance controller chip, thereby ensuring the stability of the output;

[0024] 4. Furthermore, the present application adopts a fixed voltage of the RFmin signal pin and a level change relationship between the PFC_STOP signal pin and the STBY signal pin to ensure that as long as the STBY signal is low, the second level setting circuit is triggered, the STBY signal pin is set to the second level, the second PWM signal is output, and the converter output voltage is driven. After the output voltage is detected, the STBY signal pin is set to the first level, the output of the second PWM signal is stopped, and the second level setting circuit is triggered at the same time, and the cycle is repeated to increase the frequency of outputting the second PWM signal and not outputting the second PWM signal, thereby stabilizing the ripple. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the output timing structure of the prior art;

[0026] Figure 2 This is a schematic diagram of the output voltage stabilization timing structure of a specific embodiment of the utility model;

[0027] Figure 3 This is a schematic diagram of the LLC resonant converter circuit structure of a specific embodiment of the utility model;

[0028] Figure 4 This is a schematic diagram of the circuit structure of a high-voltage resonant controller of a specific embodiment of the utility model;

[0029] Figure 5 This is a schematic diagram of the structure of a driving circuit of a specific embodiment of the utility model;

[0030] Figure 6 This is a schematic diagram of the secondary rectifier filter circuit structure of a specific embodiment of the utility model;

[0031] Figure 7 This is a schematic diagram of the battery voltage sampling circuit structure of a specific embodiment of the utility model;

[0032] Figure 8 This is a schematic diagram of the structure of an output voltage sampling circuit of a specific embodiment of the utility model;

[0033] Fig. 9 This is a schematic diagram of the main control circuit structure of a specific embodiment of the utility model;

[0034] Fig.10 This is a schematic diagram of the structure of a current modulation circuit of a specific embodiment of the utility model;

[0035] Fig.11 The utility model is a schematic diagram of a voltage and current calculation circuit structure of a specific embodiment of the utility model. DETAILED DESCRIPTION

[0036] The utility model is further described in detail below in conjunction with the accompanying drawings.

[0037] An LLC resonant converter of the present application adopts L6599 as the LLC resonant converter of the high-voltage resonant controller. In burst mode, the slope of the STBY signal rising from a first voltage of 1.24V to a second voltage of 1.29V is increased, and the rise time is reduced. At this time, the PFC_STOP signal is at a low level, and the slope falling from 1.29V to 1.24V is increased, and the fall time is reduced. At this time, the PFC_STOP signal is at a high level, thereby increasing the first signal frequency of outputting the second PWM signal and not outputting the second PWM signal, and reducing the ripple and power consumption of the output voltage of the LLC resonant converter, where the PFC_STOP signal is the first signal.

[0038] In a specific embodiment of the present application, under no-load and light-load conditions, the LLC resonant converter enters the burst mode, the STBY signal is set to be less than or equal to the first voltage 1.24V, the output of the second PWM signal is turned off, the PFC_STOP signal is at a low level, and after detecting that the PFC_STOP signal is at a low level, the STBY signal is set to be greater than or equal to the second voltage 1.29V, the second PWM signal is output, the PFC_STOP signal becomes a high level, and after detecting that the second PWM signal is output, the STBY signal is set to be less than or equal to the first voltage 1.24V, and the output of the second PWM signal is turned off again, and the burst mode operation is performed in this cycle.

[0039] The STBY signal is quickly set. When the STBY signal is detected to be a low level of 1.24V, the STBY signal is adjusted to a high level of 1.29V. When the STBY signal is detected to be a high level of 1.29V, the STBY signal is adjusted to a low level of 1.24V. This quick setting obtains a PFC_STOP signal with the same frequency. The second PWM signal is modulated with the PFC_STOP signal as the first signal to obtain a high-frequency modulated second PWM signal, which drives the output of the converter and reduces the output voltage ripple.

[0040] The working timing in burst mode, such as Figure 2 As shown, it includes: when the LLC resonant converter works in the burst mode, the hiccup frequency is increased, that is, the first duration of not applying the second PWM signal each time is reduced, the second duration of applying the second PWM signal each time is reduced, the frequency of applying the second PWM signal and not applying the second PWM signal is increased, the second PWM signal is modulated with the first signal, and the frequency of the first signal is increased, so as to achieve the purpose of reducing the output voltage ripple and reducing the power consumption.

[0041] The frequency of the first signal is greater than 1 KHz.

[0042] In a specific embodiment of the present application, the first signal frequency is greater than or equal to 3 KHz.

[0043] An LLC resonant converter circuit of the present application, such as Figure 3 As shown, it includes a mains conversion circuit, a control circuit, a high-voltage resonant controller circuit, a drive circuit, an LLC circuit and a secondary rectifier and filter circuit. The mains conversion circuit is used to convert the mains AC power into DC power, provide DC high voltage to the LLC circuit, provide a first DC voltage to the control circuit and provide a second DC voltage to the high-voltage resonant controller circuit. The control circuit, the high-voltage resonant controller circuit, the drive circuit, the LLC circuit and the secondary rectifier and filter circuit are connected in sequence. The control circuit is also connected to the secondary rectifier and filter circuit to collect output voltage and output current, and control the PWM signal output of the high-voltage resonant controller circuit according to the sampling result. The drive circuit is used to drive the half-bridge power tube in the LLC circuit to be turned on or off according to the PWM signal.

[0044] The ground of the high-voltage resonant controller circuit and the driving circuit is the first ground GND1, and the DC ground of the secondary rectifier and filter circuit is the second ground GND2. A filter capacitor is arranged between the first ground and the second ground.

[0045] The LLC circuit is also connected to the high-voltage resonant controller circuit for feeding back the voltage on the primary coil of the transformer to the high-voltage resonant controller circuit.

[0046] The control circuit includes a main control circuit, a voltage and current operation circuit and an isolation circuit connected in sequence. The main control circuit includes an MCU and a conversion circuit connected to each other, which are used to output voltage reference and current reference signals according to sampling data. The conversion circuit includes a voltage reference conversion circuit and a current reference conversion circuit. The voltage reference conversion circuit is used to convert the voltage reference signal output by the MCU into a voltage reference analog quantity, and the current reference conversion circuit is used to convert the current reference signal output by the MCU into a current reference analog quantity.

[0047] The current reference conversion circuit includes a two-stage integration circuit, a first initial value setting circuit, a first conversion filter circuit, and a current control circuit connected in sequence. The first-stage integration circuit is used to perform a first integration on the current reference signal, and the second-stage integration circuit is used to perform a second integration on the first integration result to obtain a second integration result. The first initial value setting circuit is used to set a first basic voltage for the second integration result, and the first basic circuit is superimposed on the second integration result to obtain a current reference analog quantity Iref. The first conversion filter circuit filters the current reference analog quantity Iref, and the current control circuit is used to control the output of the current reference analog quantity Iref.

[0048] The current control circuit includes a control subcircuit, a temperature control subcircuit and a voltage control subcircuit. The control subcircuit and the temperature control subcircuit are used to control the output of the current reference analog quantity Iref. The current reference analog quantity Iref is obtained after voltage division to obtain the current analog adjustment value Iref / a. The voltage control subcircuit is used to control the current analog adjustment value Iref / a.

[0049] The regulating subcircuit includes a second switch circuit, which is used to regulate the current reference analog quantity Iref according to the current reference signal.

[0050] The temperature control subcircuit includes a third switch circuit, which is used to control the current reference analog quantity Iref according to temperature changes.

[0051] The voltage regulation subcircuit includes a fourth switch circuit, which is used to regulate the current analog regulation value Iref / a according to the output voltage.

[0052] The voltage reference conversion circuit includes a secondary integration circuit, a second initial value setting circuit, and a second conversion filter circuit connected in sequence. The third integration circuit is used to perform a first integration on the current reference signal. The fourth integration circuit is used to perform a second integration on the first integration result to obtain a second integration result. The second initial value setting circuit is used to set a second basic voltage for the second integration result, increase the reference of the second integration result by the second basic voltage, and obtain a voltage reference analog quantity Vref. The second conversion filter circuit filters the voltage reference analog quantity Vref.

[0053] The isolation circuit includes an optical coupler for transmitting the comparison result of the comparison circuit to the high-voltage resonant controller circuit.

[0054] like Figure 4 As shown, the high-voltage resonant controller circuit includes a high-voltage resonant controller chip and its first peripheral circuit. In the present application, the high-voltage resonant controller chip U1 adopts L6599, and the output of the isolation circuit is used to determine whether the high-voltage resonant controller chip enters the burst mode.

[0055] The first peripheral circuit includes a first level setting circuit and a second level setting circuit. The input end of the first level setting circuit is connected to the control circuit and the high-voltage resonance controller chip, the input end of the second level setting circuit is connected to the high-voltage resonance controller chip, the output end of the first level setting circuit and the output end of the second level setting circuit are connected to the STBY signal pin of the high-voltage resonance controller chip L6599, and are used to set the STBY signal pin to the first level or the second level. In the burst mode, when the STBY signal is at the first level, the high-voltage resonance controller chip does not output the second PWM signal. At the second level, the high-voltage resonance controller chip outputs the second PWM signal to control the conversion of the STBY signal between the first level and the second level, thereby controlling the first signal frequency of the high-voltage resonance controller chip. The first signal is high when the second PWM signal is output, and is low when the second PWM signal is not output. The first signal modulates the second PWM signal to obtain the output control signal in the burst mode.

[0056] Working principle of the first level setting circuit: one input end of the first level setting circuit is connected to the RFmin signal pin of the high-voltage resonant controller chip, which is used to provide voltage to the first level setting circuit, and the other input end is connected to the output end of the isolation circuit, which is used to output the first level to the STBY signal according to the output of the isolation circuit. The input end of the second setting circuit is connected to the PFC_STOP signal pin of the high-voltage resonant controller chip, and the second level is output to the STBY signal according to the PFC_STOP signal.

[0057] Specifically, the first level setting circuit includes a series resistor combination consisting of resistors R27 / R19, which is used for voltage division. One end of the series resistor R27 is connected to the RFmin signal pin of the high-voltage resonant controller chip, and the series point of the resistors R27 / R19 is connected to the STBY signal pin. The other end of the resistor R19 is connected to the output side CON / a1 signal output end of the isolation circuit and one end of the capacitor C3. The other end of the capacitor C3 is grounded, and the other end of the output side of the isolation circuit is grounded.

[0058] The RFmin signal pin of the high voltage resonant controller chip is also grounded through a resistor R46.

[0059] The working process of the first level setting circuit: when the RFmin signal is valid, the output voltage of the RFmin signal pin is 2V, and the first level is provided to the STBY signal pin through the voltage division of the resistor R27 / R19. When the isolation circuit is turned on, the level of the CON / a1 signal is zero, and the other end of the resistor R19 is grounded. The first level is less than or equal to the first voltage 1.24V, that is, the STBY signal pin is set to be less than or equal to the first voltage, and the high-voltage resonant controller chip does not output the second PWM signal.

[0060] The second level setting circuit includes a first switching circuit, a voltage stabilizing circuit, a voltage divider circuit and a limiting circuit connected in sequence, and also includes a delay circuit, the control end of the first switching circuit is connected to the PFC_STOP signal pin, its input end is connected to the output end of the delay circuit, its output end is connected to the input end of the voltage stabilizing circuit, the output end of the voltage stabilizing circuit is connected to the input end of the voltage divider circuit, the output end of the voltage divider circuit is connected to the input end of the limiting circuit, and the output end of the limiting circuit is connected to the STBY signal pin.

[0061] The working principle of the second level setting circuit: when the PFC_STOP signal is at a low level, that is, when the high-voltage resonant controller chip does not output the second PWM signal, the first switch circuit is turned on to provide voltage to the voltage stabilizing circuit, and the voltage stabilizing circuit stabilizes the output of the first switch circuit and outputs a stable voltage of about 2.5V. The voltage divider circuit divides the 2.5V voltage to obtain a 2V voltage, which is passed through the limiting circuit to obtain a second voltage value greater than or equal to 1.29V, which is transmitted to the STBY signal pin, and the high-voltage resonant controller chip starts to output the second PWM signal. When the PFC_STOP signal is at a high level, the first switch circuit is turned off, the voltage stabilizing circuit has no output, and the level of the STBY signal pin is determined by the CON / a1 signal.

[0062] In a specific embodiment of the present application, the first level value is 1V, and the second level value is 1.3V.

[0063] The delay circuit includes a resistor R11, a capacitor EC10 and a capacitor C15. The resistor R11 and the capacitor EC10 are connected in series, and the capacitor EC10 and the capacitor C15 are connected in parallel. The other end of the resistor R11 is connected to a second voltage 15V. The capacitor EC10 is an electrolytic capacitor with its positive electrode connected to the capacitor R11 and its negative electrode grounded. The capacitor C15 is used for filtering. After power-on, the voltage on the capacitor EC10 rises to the voltage VCC after a delay setting time and is provided to the input end of the first switch circuit.

[0064] The first switch circuit includes a PNP transistor Q1 and its peripheral circuit. The base of the transistor Q1 is connected to one end of the resistor R1 and one end of the resistor R2. The other end of the resistor R2 is connected to the PFC_STOP signal pin. The other end of the resistor R1 and the emitter of the transistor Q1 are connected to the output end of the delay circuit, that is, the voltage VCC output end, and its output end is connected to the input end of the voltage stabilizing circuit.

[0065] The voltage stabilizing circuit includes a voltage stabilizing tube U1 and its peripheral circuits. The input end of the voltage stabilizing tube U1 is connected to the output end and the voltage stabilizing end of the first switch circuit through a resistor R3 and serves as a voltage stabilizing output end. The output end of the voltage stabilizing tube U1 is grounded, and the voltage stabilizing end is grounded through a capacitor C1.

[0066] In a specific embodiment of the present application, a voltage regulator tube TL431 is used to obtain a voltage regulation result of 2.5V.

[0067] The voltage divider circuit includes a series resistor of resistors R4 / R5, one end of the resistor R4 is connected to the output of the voltage stabilizing circuit, and the series connection point serves as the output end of the voltage divider circuit. The other end of the resistor R5 is grounded, and a capacitor C2 is connected in parallel at both ends of the resistor R5 for filtering.

[0068] The limiting circuit includes a diode combination D2, which includes two diodes. The negative end of the first diode is connected to the output end of the voltage divider circuit and the positive end is grounded. The lower end of the second diode is connected to the output end of the voltage divider circuit and the negative end serves as the output end of the second level setting circuit and is connected to the STBY signal pin.

[0069] The working process of the second level setting circuit: when the PFC_STOP signal is at a high level, the first switch circuit is turned off, and the second level setting circuit has no output. When the PFC_STOP signal is at a low level, that is, when the second PWM signal is not output, the first switch circuit is turned on, and the VCC voltage is provided to the voltage stabilizing circuit. The voltage stabilizing circuit outputs a stable voltage of 2.495V, and after the voltage divider circuit, a stable circuit of 2V is obtained, and then after the tube voltage drop of the diode, a voltage of 1.3V is obtained, which is given to the STBY signal pin. Because the voltage of 1.3V is greater than the second voltage of 1.29V, the high-voltage resonant controller chip L6599 outputs the second PWM signal.

[0070] When the output of the first level setting circuit is valid, the STBY signal pin is set to be less than or equal to the first voltage, and the high-voltage resonant controller chip L6599 does not output the second PWM signal. When the output of the second level setting circuit is valid, the STBY signal pin is set to be greater than or equal to the second voltage, and the high-voltage resonant controller chip L6599 outputs the second PWM signal. When there is no second PWM signal output, the STBY signal is set to make the chip output the second PWM signal. When there is a second PWM signal output, the STBY signal is set to make the chip not output the second PWM signal. The first signal frequency of the STBY signal is controlled to control the output of the high-voltage resonant controller chip. When the first signal is high frequency, the output ripple is reduced, and the standby power consumption during light load and no-load is reduced.

[0071] The HVG signal and LVG signal output by the high-voltage resonant controller chip are pulse signals with the same frequency and a duty cycle of 50%, and the HVG signal is inversely proportional to the LVG signal. In this application, they are collectively referred to as PWM signals. Under normal load, the PWM signal output by the high-voltage resonant controller chip is the first PWM signal, and under light load and no load, the PWM signal output by the high-voltage resonant controller chip is the second PWM signal.

[0072] The VCC voltage is divided by the series combination of resistors R15 / R64, and the divided voltage output is connected to the LINE signal pin of the high-voltage resonant controller chip. Capacitor C35 is connected in parallel at both ends of the resistor R64 for filtering, and the other end of the resistor R64 is grounded.

[0073] The Rfmin signal pin is also connected to one end of a resistor R61, the other end of the resistor R61 is connected to the Css signal pin and one end of a capacitor C26, and the other end of the capacitor C26 is grounded.

[0074] The DELAY signal pin is grounded through a resistor R62, and a capacitor C7 is connected in parallel at both ends of the resistor R62.

[0075] The CF signal pin is grounded through capacitor C38. The VBOOT signal pin is grounded through capacitor C16.

[0076] The ISEN signal pin is connected to one end of the capacitor C40, one end of the resistor R16, one end of the resistor R66, and one end of the diode combination D1, and the other end of the capacitor C40, the other end of the resistor R16, and the other end of the resistor R66 are grounded.

[0077] The diode combination D1 includes two diodes, the cathode of the third diode is connected to the ISEN signal pin, the anode of the fourth diode is grounded, the anode of the third diode and the cathode of the fourth diode are connected to one end of the resistor R23, the resistor R23, the resistor R65, the capacitor C31, and the capacitor C30 are connected in series, and the other end of the series combination is connected to the T1M signal terminal of the transformer primary, that is, the second lead-out terminal. The series combination of the resistor R23 and the resistor R65 and the parallel combination of the resistor R16 and the resistor R66 divide the voltage T1M of the second lead-out terminal of the transformer primary and transmit it to the ISEN signal pin. The series combination of the capacitor C31 and the capacitor C30 is used to isolate the T1M alternating current of the second lead-out terminal of the transformer primary, filter out the DC component, and retain the AC component. The anode of the third diode is used to ensure the unidirectionality of the current.

[0078] The HVG signal pin is connected to one input terminal of the driving circuit, namely the HIN terminal, through a resistor R49, and the LVG signal pin is connected to another input terminal of the driving circuit, namely the LIN terminal, through a resistor R50.

[0079] like Figure 5 As shown, the driving circuit includes a driving chip and a peripheral circuit. The Vdd signal pin of the driving chip U2 is connected to the 15V power supply terminal, and its VB signal pin is connected to the negative end of the diode D15 and one end of the capacitor C25. The positive end of the diode D15 is connected to the 15V power supply, and the other end of the capacitor C25 is connected to the VS signal pin; its HIN signal pin (P-12) is connected to the HVG signal pin output by the high-voltage resonant controller chip through a resistor R49, and its LIN signal pin (P-14) is connected to the LVG signal pin output by the high-voltage resonant controller chip through a resistor R50, and its SD signal pin (P-13) and COM2 signal pin (P-2) are grounded. Its HO signal pin is connected to one end of resistor R78 and the negative end of diode D10, the other end of resistor R78 and the positive end of diode D10 are connected to the control electrode of the third power tube Q3 and one end of resistor R80, the VS signal pin (P-6) is connected to the output electrode of the third power tube Q3, the other end of resistor R80, one end of the inductor L2 of the LLC circuit, and the input electrode of the fourth power tube Q4, and the input electrode of the third power tube Q3 is connected to the HV power supply end of the AC power conversion circuit; its LO signal pin is connected to one end of resistor R81 and the negative end of diode D11, the other end of resistor R81 and the positive end of diode D11 are connected to the control electrode of the fourth power tube Q4 and one end of resistor R82, and the other end of resistor R82 and the output electrode of the fourth power tube Q4 are grounded.

[0080] A half bridge is provided between the VB signal pin and the VS signal pin of the driver chip U2, and the output end of the half bridge is the HO signal pin. When the third power tube Q3 is turned off and the fourth power tube Q4 is turned on, the 15V power supply passes through the diode D15, the capacitor C25, and the fourth power tube Q4 to the ground, and the capacitor C25 is charged in the meantime. The voltage of the VB signal pin connected to the capacitor C25 to the ground is the sum of the voltage on the capacitor C25 and the voltage at the DS end of the fourth power tube Q4. When the third power tube Q3 is turned on and the fourth power tube Q4 is turned off, because the voltage of the output end of the third power tube Q3 to the ground is the voltage at the DS end of the fourth power tube Q4, the driving voltage of the control end of the third power tube Q3 is equal to the voltage across the capacitor C25, and the third power tube Q3 can be driven to turn on.

[0081] For example, when the fourth power tube Q4 is turned off, the voltage at the output end of the third power tube Q3 is assumed to be 200V, and the voltage across the capacitor C25 is 15V after charging. Then, the voltage of the VB signal pin connected to the capacitor C25 to the ground is 215V, which has enough energy to drive the third power tube Q3.

[0082] The LLC circuit includes an inductor L, a transformer primary coil, and a capacitor C28 connected in sequence. The other end of the capacitor C28 is grounded. The series connection point of the transformer primary coil and the capacitor C28 is connected to one end of the capacitor C27. The other end of the capacitor C27 is connected to the HV power supply end of the AC power conversion circuit.

[0083] The third power tube Q3 is used as the upper tube of the half bridge, and the fourth power tube Q4 is used as the lower tube of the half bridge. HV is 400Vdc, which is equivalent to GND for the LLC AC circuit. Capacitors C27 and C28 are in an equivalent parallel relationship and serve as a resonant capacitor together. When the upper tube is turned on, the current passes through the upper tube, inductor L2, and the primary coil of the transformer to charge the resonant capacitor. When the lower tube is turned on, the energy stored in the resonant capacitor forms a loop through the primary coil of the transformer, the inductor L2, and the lower tube. The current direction in the primary coil of the transformer changes, and an alternating magnetic field is formed in the primary coil of the transformer. The secondary of the transformer has an AC output.

[0084] like Figure 6 As shown, the secondary rectification and filtering circuit includes a secondary rectification circuit and a secondary filtering circuit. One end of the secondary coil is connected to the negative end of the diode D8, and the other end is connected to the negative end of the diode D9. The positive end of the diode D8 and the positive end of the diode D9 are grounded.

[0085] Diode D8 and diode D9 are used to rectify the secondary alternating current.

[0086] The third end of the secondary coil serves as the positive output end, the detection end of the transformer output CHR+, and is connected to one end of the filter capacitor EC3, one end of the capacitor EC4, one end of the capacitor C49, one end of the resistor R22, and one end of the inductor L3. The other end of the capacitor EC3, the other end of the capacitor EC4, the other end of the capacitor C49, and the other end of the resistor R22 are connected to the DC ground.

[0087] The other end of the inductor L3 is connected to one end of the capacitor EC8, a switch end of the relay RY1, one end of the parallel resistor R26 / R24 / R25 is DC grounded, and the other end is connected to the other end of the capacitor EC8, an input end of the common-mode inductor LF2, and one end of the capacitor CY5, and serves as the output current sampling end LOAD. The other switch end of the relay RY1 serves as the battery voltage BAT+ sampling end, connected to the other input end of the common-mode inductor LF2 and one end of the capacitor CY9; an output end of the common-mode inductor LF2 is connected to one end of the capacitor CY6, one end of the capacitor C32, and one end of the fuse F2; the other output end of the common-mode inductor LF2 is connected to one end of the capacitor CY10 and the other end of the capacitor C32, and serves as the negative output end of the LLC resonant converter circuit; the other end of the fuse F2 serves as the positive output end of the LLC resonant converter circuit.

[0088] The other end of the capacitor CY5, the other end of the capacitor CY6, the other end of the capacitor CY9, and the other end of the capacitor CY10 are connected to the ground for performing differential mode filtering on the output of the transformer.

[0089] The parallel resistor R26 / R24 / R25 combination is used to detect the output current, and the relay RY1 is used to disconnect or connect the output voltage.

[0090] The driving circuit of relay RY1 is a control switch circuit, which includes an NPN transistor Q13 and its peripheral circuit. The base of transistor Q13 is connected to the RY_OUT signal output terminal of the control circuit through a resistor R46, its emitter is grounded, and its collector is connected to one end of the relay RY1 coil and the positive electrode of the diode D13. The other end of the relay RY1 coil and the negative electrode of the diode D13 are connected to the 12.5V DC power supply terminal through a parallel resistor combination R31 / R32 / R47, which is used to apply a 12.5V voltage to the relay RY1 coil when the transistor Q13 is turned on.

[0091] After the relay RY1 is powered on, the relay switch is closed and the transformer secondary voltage is output. After the relay switch is opened, the transformer secondary voltage is not output.

[0092] The sampling circuit includes a battery voltage sampling circuit, a temperature sampling circuit and a current sampling circuit, such as Figure 7As shown, the battery voltage sampling circuit and the first temperature sampling circuit are used to divide the BAT+ voltage of the transformer secondary through the series resistor R9b / R29b to obtain the battery voltage sampling value VBAT, which is transmitted to the main control circuit. The first temperature sensor output at J1b is filtered by the series connected resistor R7b and capacitor C8b to obtain the first temperature sampling value VTM1, which is transmitted to the main control circuit.

[0093] like Figure 8 As shown, the output voltage sampling circuit and the second temperature sampling circuit are used to divide the CHR+ voltage of the transformer secondary through the series resistor R10b / R12b to obtain the output voltage sampling value VOUT, which is transmitted to the main control circuit. The second temperature sensor output at J2b is filtered by the series connected resistor R8b and capacitor C10b to obtain the second temperature sampling value VTM2, which is transmitted to the main control circuit.

[0094] like Fig. 9 As shown, the main control circuit includes a main control chip U3 and its peripheral circuits, receives sampling parameters, including temperature sampling values ​​VTM1 / VTM2, battery voltage sampling parameters VBAT, and output voltage sampling parameters VOUT, performs PID operation according to the sampling parameters, obtains a current reference signal IPWM, a voltage reference signal VPWM, and an adjustment signal ILOAD, performs an integral operation on the voltage reference signal VPWM, converts the VPWM signal into an analog quantity, and obtains a voltage reference analog quantity Vref. According to the adjustment signal ILOAD, performs an integral operation on the voltage reference signal VPWM, converts the IPWM signal into an analog quantity, and obtains a voltage reference analog quantity Iref.

[0095] like Fig.10 As shown, the current modulation circuit includes a current reference conversion circuit, a temperature control subcircuit, and a voltage control subcircuit. The output of the temperature control subcircuit and the output of the voltage control subcircuit are respectively connected to the output of the current reference conversion circuit for modulating the current.

[0096] The current reference conversion circuit comprises a secondary integration circuit, a first initial value setting circuit, a first conversion filter circuit, a second switch circuit, and a regulating circuit which are connected in sequence.

[0097] One end of the resistor R3b and one end of the resistor R30b are connected to the current reference signal IPWM output end of the main control chip U3, and the other end thereof is connected to one end of the capacitor C4b and one end of the resistor R4b. The other end of the resistor R4b is connected to one end of the resistor R13b, one end of the capacitor C5b, one end of the resistor R14b, one end of the capacitor C53b, one end of the capacitor C14b, one end of the resistor R31b, and the positive electrode of the diode D1B. The other end of the resistor R13b is connected to a 5V power supply, and the other end of the capacitor C4b, the other end of the capacitor C5b, the other end of the resistor R14b, the other end of the capacitor C53b, and the other end of the capacitor C14b are grounded. The cathode of the diode D1B is connected to the adjustment signal ILOAD output end of the main control chip U3 through the resistor R24b. The other end of the resistor R31b is connected to the collector of the NPN transistor Q7. The other end of the resistor R30b is connected to the base of the transistor Q7, and the emitter of the transistor Q7 is grounded.

[0098] The resistor R3b and the capacitor C4b form a first-stage integration circuit for performing a first integration on the IPWM signal; the resistor R4b and the capacitor C5b form a second-stage integration circuit for performing a second integration on the first integration result; the resistor R13b and the resistor R14b are connected in series to divide the 5V voltage, and a first basic voltage is set for the second integration result at the series connection point, that is, the reference of the second integration result is increased by the first basic voltage to obtain the current reference analog quantity Iref, and the capacitor C53b and the capacitor C14b filter the current reference analog quantity Iref; the series combination of the diode D1B and the resistor R24b forms a control subcircuit for controlling the output of the current reference analog quantity Iref according to the adjustment signal ILOAD; the transistor Q7, the resistor R30b, and the resistor R31b form a switch circuit for regulating the basic voltage of the current reference analog quantity Iref.

[0099] When the regulation signal ILOAD is at a low level, the regulation subcircuit pulls down the current reference analog quantity Iref. The voltage of the current reference analog quantity Iref is a single diode tube voltage, that is, 0.7V. When the regulation signal ILOAD is at a high level, the size of the current reference analog quantity Iref is determined by the current reference signal IPWM.

[0100] When the current reference signal IPWM is at a high level, the transistor Q7 is turned on, and the resistors R14b and R31b are connected in parallel and then connected in series with the resistor R13b, thereby reducing the first basic voltage. When the current reference signal IPWM is at a low level, the transistor Q7 is turned off, and the resistors R13b and R14b are connected in series to obtain the first basic voltage.

[0101] The current reference analog quantity Iref is divided to obtain a current analog adjustment value Iref / a for subsequent amplification operation. The current analog adjustment value Iref / a corresponds to the first ground GND1.

[0102] The series resistors R68 / VR1 / R63 divide the current analog adjustment value Iref / a, and obtain the current analog adjustment value Iref / a at the adjustable end of the variable resistor VR1. The current analog adjustment value Iref / a corresponds to the second ground GND2. The first ground GND1 is connected to the second ground GND2 through the series capacitors CY11 / CY12.

[0103] The temperature control sub-circuit includes a third switching circuit, which includes an NPN transistor Q9 and its peripheral circuits, a series resistor combination of resistors R71 / RT2 / R70, which divides the 12.5V power supply. Resistor RT2 is a thermistor. The base of the transistor Q9 is connected at the series point of resistors RT2 / R70. The collector of the transistor Q9 is connected to the output end of the current reference analog quantity Iref through a resistor R69, and its emitter is connected to the second ground GND2.

[0104] The voltage regulation subcircuit includes a fourth switch circuit, which includes an NPN transistor Q8 and its peripheral circuit. The negative end of the voltage regulator ZD3 is connected to the sampling voltage CHR+ of the positive output end of the secondary winding of the transformer, and the positive end is connected to one end of the resistor R121, one end of the capacitor C45, and one end of the resistor R122. The other end of the resistor R122 is connected to one end of the capacitor C45 and the base of the transistor Q8. The collector of the transistor Q8 is connected to the output end of the current analog adjustment value Iref / a through the resistor R109. The other end of the resistor R121, the other end of the capacitor C45, and the other end of the capacitor C45 are connected to the second ground GND2.

[0105] After the secondary output sampling voltage CHR+ passes through the voltage regulator ZD3, a voltage drop of the sampling voltage minus the voltage regulation value is obtained on the resistor R121. After this voltage drop passes through the resistor R122, it controls the conduction or cutoff of the transistor Q8. When the secondary output increases to exceed the first set value, the transistor Q8 is turned on, and the resistor R109 is connected in parallel with the resistor R63 to increase the current analog adjustment value Iref / a. When the secondary output decreases to below the second set value, the transistor Q8 is turned off, and the current analog adjustment value Iref / a remains unchanged.

[0106] like Fig.11 As shown, it includes a voltage reference conversion circuit and a voltage-current operation circuit, and the voltage-current operation circuit includes a voltage operation circuit and a current operation circuit. The output of the voltage reference conversion circuit is connected to the input of the voltage operation circuit.

[0107] In the voltage reference conversion circuit, one end of the resistor R25b is connected to the VPWM signal output end of the main control chip, and the other end is connected to one end of the resistor R2b and one end of the capacitor C1b. The other end of the resistor R2b is connected to one end of the resistor R26b, one end of the capacitor C2b, one end of the resistor R28b, and one end of the capacitor C3b, and serves as the output end of the voltage reference analog quantity Vref; the other end of the capacitor C1b, the other end of the capacitor C2b, the other end of the resistor R28b, and the other end of the capacitor C3b are connected to the second ground, and the other end of the resistor R26b is connected to a 5V power supply.

[0108] Resistor R25b and capacitor C1b form a first integration circuit to perform a first integration on the VPWM signal. Resistor R2b and capacitor C2b form a second integration circuit to integrate the first integration result again. The series combination of resistors R26b / R28b divides the 5V power supply, increases the second integration result by a basic DC voltage, and obtains the voltage reference analog quantity Vref.

[0109] The voltage operation circuit includes an operational amplifier U4A and its peripheral circuits, which are used to perform operations based on the voltage reference analog quantity Vref and the secondary output voltage CHR+, and the obtained operation results are transmitted to the isolation circuit.

[0110] The positive input terminal of the operational amplifier U4A is connected to one end of the resistor R35a, one end of the resistor R33a, and one end of the capacitor C23a. The other end of the resistor R33a is connected to the adjustable end of the adjustable resistor VR2. One end of the adjustable resistor VR2 is connected to the output end of the voltage reference analog quantity Vref. The other end of the resistor R35a and the other end of the capacitor C23a are grounded.

[0111] The negative input terminal of the operational amplifier U4A is connected to one end of the resistor R81a, one end of the resistor R76a, one end of the capacitor C22a, and one end of the resistor R49a. The other end of the resistor R76a is connected to the second ground. The series combination of resistors R81a / R54 / R52 is connected to the secondary output voltage CHR+ terminal. The other end of the resistor R49a is connected to one end of the capacitor C18a. The other end of the capacitor C18a and the other end of the capacitor C22a are connected to the output terminal of the operational amplifier U4A. The output terminal of the operational amplifier U4A is connected to the negative end of the diode D14a. The positive end of the diode D14a is connected to an input terminal CON / a on the input side of the optocoupler U5 in the isolation circuit.

[0112] The current operation circuit includes an amplifier circuit and a comparison subcircuit connected in sequence. The amplifier circuit includes an operational amplifier U4B and its peripheral circuits, which are used to amplify the output current sampling value LOAD.

[0113] The positive input terminal of the operational amplifier U4B is connected to one end of the resistor R77a and one end of the capacitor C52a, the other end of the resistor R77a is connected to one end of the capacitor C41a and the output end of the output current sampling value LOAD, the other end of the capacitor C52a and the other end of the capacitor C41a are connected to the second ground. The capacitors C41a / C52a are used for filtering.

[0114] The negative input terminal of the operational amplifier U4B is connected to one end of the resistor R78a, one end of the capacitor C42a, and one end of the resistor R79a. The other end of the resistor R78a is connected to the second ground. The other end of the capacitor C42a and the other end of the resistor R79a are connected to the output end of the operational amplifier U4B, one end of the resistor R39a, and one end of the resistor R50a. The other end of the resistor R50a is connected to the CHRI signal input terminal of the main control chip U3.

[0115] The second comparison sub-circuit includes an operational amplifier U4C and its peripheral circuits. The positive input terminal of the operational amplifier U4C is connected to one end of the resistor R60a, one end of the resistor R63a, and one end of the capacitor C28a. The other end of the resistor R60a is connected to the output end of the current analog adjustment value Iref / a. The other end of the resistor R63a and the other end of the capacitor C28a are connected to the second ground.

[0116] The negative input terminal of the operational amplifier U4C is connected to one end of the resistor R88a, the other end of the resistor R39a, and one end of the capacitor C43a. The other end of the resistor R88a is connected to one end of the capacitor C44a. The other end of the capacitor C44a and the other end of the capacitor C43a are connected to the output end of the operational amplifier U4C and the negative end of the diode D17a. The positive end of the diode D17a is connected to an input terminal CON / a on the input side of the optocoupler U5 in the isolation circuit.

[0117] The working principle of the LLC resonant converter circuit in this application:

[0118] The control circuit detects the sampling values ​​of the secondary output voltage CHR+ and the battery voltage BAT+, samples the temperature value VTM1 / VTM2, divides the secondary output voltage CHR+ to obtain the output voltage detection value VOUT, divides the battery voltage BAT+ to obtain the battery voltage detection value VBAT, and the main control chip in the control circuit outputs the current reference signal IPWM and the voltage reference signal VPWM according to the detection value and the temperature sampling value, converts the pulse signal of the current reference signal IPWM into the current reference analog quantity, and converts the pulse signal of the voltage reference signal VPWM into the voltage reference analog quantity; according to the secondary output voltage CHR+ and the temperature change, the current reference analog quantity is regulated to obtain the current analog adjustment value Iref / a, the output current sampling value LOAD is amplified, and the amplification result is calculated with the current analog adjustment value Iref / a to obtain the CON / a signal; which is used to control the conduction of the optical coupler U5 in the isolation circuit. The voltage reference analog quantity is calculated with the secondary output voltage CHR+ to obtain the CON / a signal; the CON / a signal is used to control the conduction of the optical coupler U5 in the isolation circuit.

[0119] The Rfmin signal pin of chip L6599 outputs a 2V voltage. When the optocoupler U5 is cut off, the Rfmin signal charges the capacitor C3 through the series resistors R27 / R19. The voltage at the series point of capacitor C3 and resistor R19 is equal to 2V. The capacitor C39 is charged through resistor R27. After being fully charged, the STBY signal pin is 2V, and the chip L6599 enters normal working state.

[0120] When the optocoupler U5 is turned on, after voltage division by the series resistors R27 / R19, a voltage less than the first voltage 1.24V is obtained and given to the STBY signal pin, the HIN / LIN signal pin of the chip L6599 has no signal output, and the PFC_STOP signal pin outputs a low level. After passing through the switching circuit and the voltage stabilizing circuit, the STBY signal pin is set to a voltage greater than the second voltage 1.29V, and the HIN / LIN signal pin of the chip L6599 outputs the second PWM signal.

[0121] The voltage of the STBY signal pin is quickly converted to increase the frequency of the first signal, thereby increasing the frequency of applying the second PWM signal and not applying the second PWM signal, thereby reducing the output voltage ripple.

[0122] The above are all preferred embodiments of the present utility model, and are not intended to limit the protection scope of the present utility model. Therefore, any equivalent changes made based on the structure, shape, and principle of the present utility model should be included in the protection scope of the present utility model.

Claims

1. An LLC resonant converter, characterized in that: The utility model comprises a mains conversion circuit, a control circuit, a high-voltage resonant controller circuit, a drive circuit, an LLC circuit and a secondary rectifier filter circuit. The mains conversion circuit is used for converting the mains AC power into DC power to provide electric energy to the converter. The control circuit, the high-voltage resonant controller circuit, the drive circuit, the LLC circuit and the secondary rectifier filter circuit are connected in sequence. The control circuit is also connected to the secondary rectifier filter circuit and is used for receiving the sampling value of the secondary rectifier filter circuit and outputting the mode control signal corresponding to the different working modes to the high-voltage resonant controller circuit according to the sampling value. The high-voltage resonant controller circuit is used for outputting different PWM signals to the drive circuit according to the mode control signal. In the normal mode, the first PWM signal is output to the drive circuit. In the burst mode, the second PWM signal and the modulation wave of the high-frequency first signal are output to the drive circuit. The drive circuit drives the LLC circuit to work according to the PWM signal and outputs the high-frequency stable voltage after passing through the secondary rectifier filter circuit.

2. The LLC resonant converter according to claim 1, characterized in that: The control circuit includes a main control circuit, a voltage and current calculation circuit and an isolation circuit connected in sequence. The main control circuit is used to output a current reference analog quantity and a voltage reference analog quantity to a comparison circuit according to sampling parameters of the converter. The comparison circuit compares the output voltage sampling value with the voltage reference analog quantity, and compares the current sampling value with the current reference analog quantity, outputs a first comparison signal to the isolation circuit, and outputs a mode control signal through the isolation circuit.

3. An LLC resonant converter according to claim 2, characterized in that: The main control circuit includes an MCU and a conversion circuit connected to each other. The MCU outputs a voltage reference signal and a current reference signal according to sampling parameters. The conversion circuit is used to convert the voltage reference signal into a voltage reference analog quantity and convert the current reference signal into a current analog adjustment value.

4. The LLC resonant converter according to claim 3, characterized in that: The conversion circuit includes a voltage reference conversion circuit and a current reference conversion circuit. The current reference conversion circuit includes a first integration circuit, a first initial value setting circuit, a first conversion filter circuit, and a current control circuit connected in sequence. The first integration circuit is used to integrate the current reference signal. The first initial value setting circuit is used to superimpose the integration result with the first initial value to obtain the current reference analog quantity Iref. The first conversion filter circuit filters the current reference analog quantity. The current reference analog quantity is divided to obtain a current analog adjustment value. The current control circuit is used to control the current reference analog quantity according to the current reference signal, the temperature signal and the output voltage, and control the current analog adjustment value according to the output voltage.

5. The LLC resonant converter according to claim 4, characterized in that: The current control circuit includes a control subcircuit, a temperature control subcircuit and a voltage control subcircuit. The control subcircuit includes a second switch circuit for controlling the current reference analog quantity Iref according to the current reference signal; the temperature control subcircuit includes a third switch circuit for controlling the current reference analog quantity Iref according to temperature changes; the voltage control subcircuit includes a fourth switch circuit for controlling the current analog adjustment value Iref / a according to the output voltage.

6. The LLC resonant converter according to claim 2, characterized in that: The voltage-current operation circuit includes a voltage operation circuit and a current operation circuit. The input of the voltage operation circuit is connected to the output end of the voltage reference conversion circuit and the output voltage sampling end in the main control circuit, and its output is connected to the input end of the isolation circuit; the input of the current operation circuit is connected to the output end of the current reference conversion circuit and the output current sampling end in the main control circuit, and its output is connected to the input end of the isolation circuit and the main control circuit.

7. The LLC resonant converter according to claim 1, characterized in that: The high-voltage resonance controller circuit includes a high-voltage resonance controller chip, a first level setting circuit and a second level setting circuit. The high-voltage resonance controller chip is connected to the LLC circuit, the first level setting circuit and the second level setting circuit. The input of the first level setting circuit is connected to the control circuit and the high-voltage resonance controller chip, and is used to control the output of the first level setting circuit according to the mode control signal of the control circuit. The input and output of the second level setting circuit are both connected to the high-voltage resonance controller chip, and are used to control the output of the second level setting circuit according to the output signal of the high-voltage resonance controller chip. When the high-voltage resonance controller chip is in burst mode, the frequency of the first signal is controlled according to the first level setting circuit and the output of the first level setting circuit, and the modulated wave of the first signal and the second PWM signal is output to the drive circuit.

8. The LLC resonant converter according to claim 7, characterized in that: The high-voltage resonant controller chip includes L6599, one input end of the first level setting circuit is connected to the mode signal output end of the control circuit, the other input end is connected to the Rfmin signal pin of the high-voltage resonant controller chip, and its output end is connected to the STBY signal pin of the high-voltage resonant controller chip, which is used to set the first level for the STBY signal pin according to the mode signal, and the input end of the second level setting circuit is connected to the PFC_STOP signal pin of the high-voltage resonant controller chip, which is used to set the second level for the STBY signal pin in burst mode.

9. The LLC resonant converter according to claim 8, characterized in that: The first level setting circuit includes an RC circuit, a resistor and capacitor connection point of the RC circuit is connected to the control circuit, the resistor includes a series resistor combination, the connection point of the series resistor is connected to the STBY signal pin, and the input end of the RC circuit is connected to the Rfmin signal pin; the second level setting circuit includes a fifth switching circuit, a voltage stabilizing circuit, a voltage dividing circuit and a limiting circuit connected in sequence, the control end of the fifth switching circuit is connected to the PFC_STOP signal pin, and its output end is connected to the voltage stabilizing circuit, the voltage dividing circuit is used to divide the output of the voltage stabilizing circuit, the limiting circuit limits the voltage division result, and the output of the limiting circuit is connected to the STBY signal pin.

10. The LLC resonant converter according to claim 9, characterized in that: The voltage stabilizing circuit includes a voltage stabilizing chip for stabilizing the power supply voltage at a set value.

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