Phase-shift frequency-modulation combined control LLC circuit for space navigation

Abstract

A phase shift and frequency modulation combined control LLC circuit for space navigation comprises a voltage feedback module, a high-frequency starting module, a phase shift processing module and a frequency modulation module, a voltage negative feedback control loop is used for stabilizing output voltage, and after the output voltage is connected with the circuit input end of the frequency modulation module, a common point is connected to a circuit in the phase shift processing module. The high-frequency starting module is connected with the input positive end of the frequency modulation module through the collector of the triode; the frequency modulation module is connected through a pin of a phase shift control chip in the phase shift processing module, the frequency modulation module is driven to adjust the working mode of the circuit through a current signal and a voltage signal, and meanwhile output control of the overall voltage of the circuit is achieved through the phase shift processing module.

Description

Technical Field

[0001] The invention relates to an aerospace phase-shift frequency-modulation combined control LLC circuit, belonging to the field of space power supply technology design. Background Art

[0002] One of the future development trends of space electronic power supply units is high frequency. Switching loss limits the increase of switching frequency, so the importance of soft switching technology becomes more and more prominent. LLC converter can realize ZVS opening of full-bridge primary MOS tube and zero recovery loss of secondary rectifier diode. Because of its excellent soft switching performance, LLC converter is widely adopted as DCDC conversion topology. The Hall thruster anode power supply topology uses full-bridge LLC conversion topology, because the thruster output working condition requires 0-310V adjustable, and traditional frequency modulation control cannot achieve wide range of output adjustment. In the space field, it is limited by the selection of frequency modulation chips, and the output frequency adjustment cannot be achieved through the traditional conversion topology. Summary of the invention

[0003] The technical problem solved by the present invention is: in view of the problem that the traditional frequency modulation control in the current prior art cannot achieve wide range output regulation, a phase-shift frequency modulation combined control LLC circuit for aerospace is proposed.

[0004] The present invention solves the above technical problems by the following technical solutions:

[0005] An aerospace phase-shift frequency-modulation combined control LLC circuit comprises a voltage feedback module, a high-frequency starting module, a phase-shift processing module, and a frequency modulation module;

[0006] The voltage feedback module has a positive input terminal connected to the voltage loop given voltage, and a negative input terminal as the voltage output terminal. The output voltage signal is collected and processed by proportional integral operation, and then output to the phase shift processing module and the frequency modulation module; at the same time, the voltage is outputted at a specified frequency according to the frequency modulation signal sent by the frequency modulation module;

[0007] The high-frequency starting module completes power-on after receiving the starting voltage, determines the starting frequency according to the level status of the connection point of the high-frequency starting module and the frequency modulation module, and completes the circuit startup;

[0008] The frequency modulation module receives the voltage signal sent by the voltage feedback module and the current signal sent by the phase shift processing module, determines the output voltage of the frequency modulation module according to the two types of signals received, adjusts the circuit operating frequency based on the relationship between the output voltage and the received current signal, and sends the frequency modulation signal to the voltage feedback module;

[0009] The phase shift processing module divides the voltage signal sent by the voltage feedback module, and then adjusts the phase shift angle through the phase shift control chip according to the input voltage to adjust the current signal output to the frequency modulation module, and outputs the current signal to the frequency modulation module.

[0010] The voltage feedback module includes an operational amplifier chip U1, a resistor R7, a resistor R8, and a capacitor C2;

[0011] The positive input terminal of the operational amplifier chip U1 is connected to the given terminal Vref of the voltage loop, and the negative input terminal is connected to the output voltage Vo through the resistor R7. The negative input terminal is also connected to the connection point of R7 and one end of the resistor R8. The other end of the resistor R8 is connected to one end of the capacitor C2, and the other end of the capacitor C2 is connected to the output terminal of the operational amplifier chip U1.

[0012] The high-frequency starting module includes a transistor V3, a diode V4, a capacitor C3, a resistor R3, a resistor R5, and a resistor R6;

[0013] The collector of the transistor V3 is connected to the anode of the voltage regulator Vz, the base of the transistor V3 is connected to the anode of the diode V4 and one end of the resistor R5, the cathode of the diode V4 is connected to one end of the resistor R6, the other end of the resistor R6 is connected to the other end of the resistor R5 and then to the positive end of the external power supply, one end of the capacitor C3 is connected to the base of the transistor V3, the other end of the capacitor C3 is connected to the emitter of the transistor V3 and then to the power supply ground, one end of the resistor R3 is connected to the collector of the transistor V3, and the other end is connected to the power supply ground.

[0014] The phase shift processing module includes a phase shift control chip U3, a resistor R1, a resistor R2, a capacitor C1, and a resistor RT;

[0015] The voltage feedback loop output voltage Vfb is connected through a voltage divider of resistors R1 and R2, and the voltage divider connection point is connected to the chip EA pin of the phase shift control chip U3. The EA- pin of the phase shift control chip U3 is connected to the EAout pin. One end of the capacitor C1 and the resistor RT are connected to the power supply ground. The Frequency pin of the phase shift control chip U3 is connected to the other end of the capacitor C1, and the common connection point is connected to the frequency modulation module.

[0016] The frequency modulation module includes an operational amplifier chip U2, a diode V1, a diode V2, a diode Vz, and a resistor R4;

[0017] The positive input terminal of the operational amplifier chip U2 is connected to the collector of the transistor V3, the negative input terminal and the common point of the output terminal are connected to the cathode of the diode V2, the anode of the diode V2 is connected to one end of the resistor R4, and the other end of R4 is connected to the Frequency pin of the phase shift control chip U3; the diode V1 is connected to the cathode of the diode Vz, the anode of the diode Vz is connected to the positive input terminal of the operational amplifier chip U2, and the anode of the diode V1 is connected to the output terminal of the operational amplifier chip U1.

[0018] After the output voltage Vfb of the voltage feedback module is connected to the anode of the diode V1 in the frequency modulation module, the common point is connected to one end of the circuit R1 in the phase shift processing module; the collector of the transistor V3 in the high-frequency starting module is connected to the positive input end of the operational amplifier chip U2 in the frequency modulation module; one end of the resistor R4 in the frequency modulation module is connected to the Frequency pin of the phase shift control chip U3 in the phase shift processing module.

[0019] The phase shift control chip U3 adopts UC1875 chip, which realizes circuit frequency conversion by changing the output current of the Equency pin and transmitting it to the frequency modulation module; the phase shift control chip U3 adjusts the phase shift angle by changing the voltage at both ends of the EAOUT pin, and controls and adjusts the current signal output to the frequency modulation module according to the phase shift angle.

[0020] The frequency modulation module adjusts the circuit operating frequency based on the relationship between the output voltage and the received current signal, and determines the circuit operating mode according to the adjusted operating frequency, including PS mode and VF mode; when the input voltage of the phase shift processing module is lower than the preset value, the circuit works in VF mode; when the input voltage of the phase shift processing module is higher than the preset value, the circuit works in PS mode.

[0021] In the PS mode, when the circuit output voltage Vo is higher than the voltage loop given end Vref, the voltage value Vfb at the output end of the voltage feedback module decreases; the voltage value Vea at the input end of the phase shift processing module decreases, and the output duty cycle of the phase shift control chip U3 decreases to control the circuit output voltage Vo to achieve voltage regulation control.

[0022] When the voltage value Vfb at the output of the voltage feedback module decreases, the voltage regulator Vz is not broken down and cannot enter the VF mode;

[0023] In the VF mode, when the circuit output voltage Vo is lower than the voltage loop given end Vref, the voltage value Vfb at the output end of the voltage feedback module increases; the voltage value Vea at the input end of the phase shift processing module increases, and the output duty cycle of the phase shift control chip U3 increases to control the circuit output voltage Vo to increase and realize voltage stabilization control;

[0024] The voltage value Vfb at the output end of the voltage feedback module increases, the voltage regulator tube Vz is broken down, and the input positive terminal voltage of the operational amplifier chip U2 is Ufb-Uvz. When the input positive terminal voltage Ufb-Uvz is greater than the output voltage of the Frequency pin, the output drive frequency of the control chip U3 is reduced to increase the LLC converter resonant cavity gain.

[0025] When the PS mode is in transition to the VF mode, the initial state of the circuit is the PS mode. When the voltage value Vfb at the output end of the voltage feedback module rises to the breakdown voltage of the diode V1 and the diode Vz, the diode Vz breaks down and conducts. The voltage value of the transistor V3 is the difference between the voltage value at the output end of the voltage feedback module and the breakdown voltage value. The output current I4 of the phase shift processing module decreases, so that the output current IF of the Frequency pin decreases to reduce the circuit frequency. The circuit state changes from the PS mode to the VF mode.

[0026] In the transition state from VF mode to PS mode, the initial state of the circuit is VF mode, the input voltage Vea of ​​the phase shift processing module is greater than the preset value, and the voltage feedback module controls the output voltage value Vfb to reduce the voltage to increase the output current I4 of the phase shift processing module. The increase in the output current I4 of the phase shift processing module increases the output current IF of the Frequency pin to increase the circuit frequency, and the circuit state enters the PS mode from the VF mode until the input voltage Vea of ​​the phase shift processing module is less than the preset value.

[0027] The advantages of the present invention compared with the prior art are:

[0028] The present invention provides a phase-shift frequency modulation combined control LLC circuit for aerospace use. Through an innovative circuit design including a voltage feedback loop, a high-frequency starting circuit, a frequency modulation circuit, and a phase-shift control circuit, the circuit can realize voltage stabilization control or circuit resonant cavity gain control in different modes, and has the advantages of high transmission efficiency and wide input range. Through the phase-shift frequency modulation combined control design, the technical characteristics of high-efficiency transmission of frequency conversion control are retained, and the technical effect of a wide input range of LLC converter is achieved through phase-shift control. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The schematic diagram of the LLC circuit for phase-shift and frequency-modulation combination control for aerospace provided by the invention; DETAILED DESCRIPTION

[0030] A phase-shift and frequency-modulation combined control LLC circuit for aerospace use comprises a voltage feedback module, a high-frequency starting module, a phase-shift processing module and a frequency-modulation module. A voltage negative feedback control loop is used to stabilize the output voltage. After the output voltage is connected to the input end of the frequency-modulation module circuit, a common point is connected to the circuit in the phase-shift processing module. The high-frequency starting module is connected to the input positive end of the frequency-modulation module through the collector of a transistor. The frequency-modulation module is connected through the pin of a phase-shift control chip in the phase-shift processing module. The frequency-modulation module is driven to adjust the circuit working mode through current signals and voltage signals. At the same time, the phase-shift processing module is used to realize the output control of the overall voltage of the circuit.

[0031] The voltage feedback module has a positive input terminal connected to the voltage loop given voltage, and a negative input terminal as the voltage output terminal. The output voltage signal is collected and processed by proportional integral operation, and then output to the phase shift processing module and the frequency modulation module; at the same time, the voltage is outputted at a specified frequency according to the frequency modulation signal sent by the frequency modulation module;

[0032] The high-frequency starting module completes power-on after receiving the starting voltage, determines the starting frequency according to the level status of the connection point of the high-frequency starting module and the frequency modulation module, and completes the circuit startup;

[0033] The frequency modulation module receives the voltage signal sent by the voltage feedback module and the current signal sent by the phase shift processing module, determines the output voltage of the frequency modulation module according to the two types of signals received, adjusts the circuit operating frequency based on the relationship between the output voltage and the received current signal, and sends the frequency modulation signal to the voltage feedback module;

[0034] The phase shift processing module divides the voltage signal sent by the voltage feedback module, and then adjusts the phase shift angle through the phase shift control chip according to the input voltage to adjust the current signal output to the frequency modulation module, and outputs the current signal to the frequency modulation module.

[0035] The voltage feedback module includes an operational amplifier chip U1, a resistor R7, a resistor R8, and a capacitor C2;

[0036] The positive input terminal of the operational amplifier chip U1 is connected to the given terminal Vref of the voltage loop, and the negative input terminal is connected to the output voltage Vo through the resistor R7. The negative input terminal is also connected to the connection point of R7 and one end of the resistor R8. The other end of the resistor R8 is connected to one end of the capacitor C2, and the other end of the capacitor C2 is connected to the output terminal of the operational amplifier chip U1.

[0037] The high frequency starting module includes transistor V3, diode V4, capacitor C3, resistor R3, resistor R5, and resistor R6;

[0038] The collector of the transistor V3 is connected to the anode of the diode Vz, the base of the transistor V3 is connected to the anode of the diode V4 and one end of the resistor R5, the cathode of the diode V4 is connected to one end of the resistor R6, the other end of the resistor R6 is connected to the other end of the resistor R5 and then to the positive end of the external power supply, one end of the capacitor C3 is connected to the base of the transistor V3, the other end of the capacitor C3 is connected to the emitter of the transistor V3 and then to the power supply ground, one end of the resistor R3 is connected to the collector of the transistor V3, and the other end is connected to the power supply ground.

[0039] The phase shift processing module includes a phase shift control chip U3, a resistor R1, a resistor R2, a capacitor C1, and a resistor RT;

[0040] The voltage feedback loop output voltage Vfb is connected through a voltage divider of resistors R1 and R2, and the voltage divider connection point is connected to the chip EA pin of the phase shift control chip U3. The EA- pin of the phase shift control chip U3 is connected to the EAout pin. One end of the capacitor C1 and the resistor RT are connected to the power supply ground. The Frequency pin of the phase shift control chip U3 is connected to the other end of the capacitor C1, and the common connection point is connected to the frequency modulation module.

[0041] The frequency modulation module includes an operational amplifier chip U2, a diode V1, a diode V2, a diode Vz, and a resistor R4;

[0042] The positive input terminal of the operational amplifier chip U2 is connected to the collector of the transistor V3, the negative input terminal and the common point of the output terminal are connected to the cathode of the diode V2, the anode of the diode V2 is connected to one end of the resistor R4, and the other end of R4 is connected to the Frequency pin of the phase shift control chip U3; the diode V1 is connected to the cathode of the diode Vz, the anode of the diode Vz is connected to the positive input terminal of the operational amplifier chip U2, and the anode of the diode V1 is connected to the output terminal of the operational amplifier chip U1.

[0043] After the output voltage Vfb of the voltage feedback module is connected to the anode of the diode V1 in the frequency modulation module, the common point is connected to one end of the circuit R1 in the phase shift processing module; the collector of the transistor V3 in the high-frequency starting module is connected to the positive input end of the operational amplifier chip U2 in the frequency modulation module; one end of the resistor R4 in the frequency modulation module is connected to the Frequency pin of the phase shift control chip U3 in the phase shift processing module.

[0044] The phase shift control chip U3 adopts the UC1875 chip, which realizes circuit frequency conversion by changing the output current of the Equency pin and transmitting it to the frequency modulation module; the phase shift control chip U3 adjusts the phase shift angle by changing the voltage at both ends of the EAOUT pin, and controls and adjusts the current signal output to the frequency modulation module according to the phase shift angle.

[0045] The frequency modulation module adjusts the circuit operating frequency based on the relationship between the output voltage and the received current signal, and determines the circuit operating mode according to the adjusted operating frequency, including PS mode and VF mode; when the input voltage of the phase shift processing module is lower than the preset value, the circuit works in VF mode; when the input voltage of the phase shift processing module is higher than the preset value, the circuit works in PS mode.

[0046] In PS mode, when the circuit output voltage Vo is higher than the voltage loop given end Vref, the voltage value Vfb at the output end of the voltage feedback module decreases (negative saturation output). The voltage value Vea at the input end of the phase shift processing module decreases, and the output duty cycle of the phase shift control chip U3 decreases to control the circuit output voltage Vo to achieve voltage regulation control.

[0047] Vfb decreases, the Zener diode Vz is not broken down, and it is impossible to enter the VF (frequency modulation boost) mode.

[0048] In VF mode, when the circuit output voltage Vo is lower than the voltage loop given end Vref, the voltage value Vfb at the output end of the voltage feedback module increases (positive saturation output). The voltage value Vea at the input end of the phase shift processing module increases, and the output duty cycle of the phase shift control chip U3 increases to control the circuit output voltage Vo to achieve voltage regulation control.

[0049] And Vfb increases, the voltage regulator Vz is broken down, and the input positive terminal voltage of the operational amplifier chip U2 is Ufb-Uvz. When the input positive terminal voltage (Ufb-Uvz) is greater than the output voltage of the Frequency pin, the diode V2 is cut off, I4 is reduced to 0, IF is reduced, and the output drive frequency of the control chip U3 is reduced to increase the LLC converter resonant cavity gain.

[0050] When the PS mode is in transition to the VF mode, the initial state of the circuit is the PS mode. When the voltage value Vfb at the output end of the voltage feedback module rises to the breakdown voltage of the diode V1 and the diode Vz, the diode Vz breaks down and conducts. The voltage value of the transistor V3 is the difference between the voltage value at the output end of the voltage feedback module and the breakdown voltage value. The output current I4 of the phase shift processing module decreases, so that the output current IF of the Frequency pin decreases to reduce the circuit frequency. The circuit state changes from the PS mode to the VF mode.

[0051] In the transition state from VF mode to PS mode, the initial state of the circuit is VF mode, the input voltage Vea of ​​the phase shift processing module is greater than the preset value, and the voltage feedback module controls the output voltage value Vfb to reduce the voltage to increase the output current I4 of the phase shift processing module. The increase in the output current I4 of the phase shift processing module increases the output current IF of the Frequency pin to increase the circuit frequency, and the circuit state enters the PS mode from the VF mode until the input voltage Vea of ​​the phase shift processing module is less than the preset value.

[0052] The following is further described in conjunction with the accompanying drawings and preferred embodiments of the specification:

[0053] In the current embodiment, the LLC circuit is controlled by a combination of phase shift and frequency modulation for aerospace, and the circuit structure includes a voltage feedback loop, a high-frequency starting circuit, a frequency modulation circuit, and a phase shift control circuit;

[0054] The voltage feedback loop is used to control the frequency and phase shift angle of the LLC converter after proportional-integral operation;

[0055] At the moment of high-frequency starting circuit, +12V is powered on, which pulls down the base voltage of transistor V3, and then the collector potential of V3 is pulled down. When the frequency modulation signal is pulled down, diode V2 is turned on, and the charging current of chip UC1875 to ground increases, so the frequency increases to realize high-frequency starting.

[0056] The high-frequency starting circuit controls the time when the base of V3 is pulled low by controlling the RC time constant of R5 and C3, thereby controlling the duration of the soft start; the diode V4 and resistor R6 of the high-frequency starting circuit release the electric energy on the capacitor C3;

[0057] The specific criterion of frequency modulation of the frequency modulation circuit lies in whether the diode Vz is broken down or not. When the Zener diode is broken down, the voltage at the positive input terminal of the operational amplifier is Ufb-Uvz, and the output voltage at the output terminal of the operational amplifier U2 (that is, the diode V2) is also Ufb-Uvz; when the output terminal voltage of the operational amplifier U2 is different, the current I4 is different, and the operating frequency of the converter is different;

[0058] When the output voltage is lower, Vfb is larger, and the output end of the operational amplifier U2 is larger, I4 is smaller, the frequency decreases, and the converter reduces the frequency and increases the voltage; when the output voltage is higher, Vfb is smaller, the output end of the operational amplifier U2 is smaller, I4 is larger, the frequency increases, and the converter increases the frequency and reduces the voltage.

[0059] The voltage feedback signal Vfb of the phase-shift control circuit is connected to the EA+ pin of the phase-shift control chip UC1875 after being divided by resistors R1 and R2. The larger the Vfb, the larger the output duty cycle. The Frequency pin is charged to the ground through R4 and Rt, and frequency modulation is achieved through the current change at the I4 terminal.

[0060] Furthermore, the overall circuit structure is as follows Figure 1As shown, it includes a voltage feedback loop, a high-frequency start-up circuit, a frequency modulation circuit, and a phase shift control circuit. The voltage feedback circuit is composed of an operational amplifier chip U1, a resistor R7, a resistor R8, and a capacitor C2; the high-frequency start-up circuit is composed of a transistor V3, a diode V4, a capacitor C3, a resistor R3, a resistor R5, and a resistor R6; the phase shift frequency modulation circuit is composed of a phase shift control chip U3 (UC1875), a resistor R1, a resistor R2, a capacitor C1, and a resistor RT; the frequency modulation circuit is composed of an operational amplifier chip U2, diodes V1, V2, Vz, and a resistor R4.

[0061] The connection relationship of the voltage feedback circuit is as follows: the positive input terminal of the operational amplifier U1 is connected to the voltage loop given value (Vref), the negative input terminal of the operational amplifier is connected to the output voltage Vo (controlled quantity) through the resistor R7, the connection point between the negative terminal of the operational amplifier U1 and R7 is also connected to one end of the resistor R8, the other end of the resistor R8 is connected to the capacitor C2, and the other end of the capacitor C2 is connected to the output terminal of the operational amplifier U1;

[0062] The connection relationship of the high-frequency starting circuit is:

[0063] The collector of the PNP transistor V3 is connected to the anode of the diode Vz and the positive input terminal of the operational amplifier, the base of the transistor V3 is connected to the anode of the diode V4 and one end of the resistor R5, the cathode of the diode V4 is connected to one end of the resistor R6, the other end of the resistor R6 is connected to the other end of the resistor R5 and then connected to the +12V power supply positive terminal, one end of C3 is connected to the base of the transistor V3, the other end of C3 is connected to the emitter of the transistor V3 and then connected to the power supply ground. One end of the resistor R3 is connected to the collector of the transistor V3, and the other end is connected to the power supply ground.

[0064] The connection relationship of the phase shift (duty cycle) control circuit is:

[0065] The phase shift (duty cycle) control circuit takes the UC1875 chip as an example, including but not limited to UC1875. The voltage feedback loop output voltage Vfb is connected to the chip EA pin after voltage division, EA- is connected to EAout, one end of Rt and C1 is connected to the power supply ground, and the other end is connected to the Frequency pin of the chip.

[0066] The connection relationship of the frequency modulation circuit is:

[0067] The positive input terminal of the operational amplifier U2 is connected to the collector of the transistor V3, the negative output terminal of the operational amplifier is connected to the output terminal of the operational amplifier and then connected to the cathode of the diode V2, the anode of the diode V2 is connected to one end of the resistor R4, and the other end of R4 is connected to the Frequency pin of the UC1875. The cathodes of the diodes V1 and Vz are connected to each other, and the anode of the diode Vz is connected to the positive input terminal of the operational amplifier U2. The anode of the diode V1 is connected to the output terminal of the operational amplifier U1.

[0068] The connection relationship between the several circuits is:

[0069] The output voltage Vfb of the voltage feedback circuit is connected to the anode of the diode V1 of the frequency modulation circuit and then connected to one end of the resistor R1 in the phase shift (duty cycle) control circuit; the collector of the transistor V3 in the high-frequency starting circuit is connected to the positive input terminal of U2 in the frequency modulation circuit; one end of the resistor R4 in the frequency modulation circuit is interconnected with the Frequency pin of the phase shift control chip U3 in the phase shift control circuit.

[0070] The circuit structure design details are as follows:

[0071] (1) The UC1875 chip is a high-performance PWM phase-shift control chip. It controls the phase shift angle by changing the voltage of the EAOUT pin, and can also achieve frequency conversion by changing the output current of the Frequency pin. Under high-voltage output conditions, when the input voltage is low, the converter works in the frequency conversion mode; when the input voltage is high, the converter works in the phase-shift mode. Under half-voltage output conditions, the highest operating frequency of the frequency conversion mode cannot be achieved, and it needs to work in the phase-shift mode.

[0072] (2) The phase shift angle can be controlled by changing the voltage of the EAOUT pin, and the frequency conversion can be achieved by changing the output current of the Frequency pin;

[0073] (3) PS mode voltage regulation working process: Vfb<5.6*(1+R2 / R1), Vo↑→Vfb↓→Vea↓→D↓→Vo↓;

[0074] (4) VF mode voltage regulation working process: Vfb>(V1+Vz), Vo↑→Vfb↓→V3↓→I4↑→IF↑→fs↑→Vo↓;

[0075] (5) Transition from PS mode to VF mode: In the initial state, the converter operates in PS mode, fs = fmax, IF = IT + (I4) max, (I4) max = (Vc - V2) / R4. When Vfb rises to a value greater than V1 + Vz, Vz breaks down and conducts, V3 = Vfb - (V1 + Vz), I4 current decreases, IF current decreases, frequency decreases, and the converter exits PS mode and enters VF mode.

[0076] (6) Transition from VF mode to PS mode: In the initial state, the converter operates in VF mode, Vea>5.6V, and the duty cycle is 1. As Vfb decreases, I4 is controlled to increase, thereby controlling the increase in frequency. When Vfb=(V1+Vz), fs=fmax; when Vfb=5.6*(1+R2 / R1), the converter exits VF mode and enters PS mode, and IF is limited to IT+(I4)max. Vfb decreases again, Vea<5.6V, and phase shifting begins, and the actual duty cycle decreases.

[0077] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

[0078] The contents not described in detail in the specification of the present invention belong to the common knowledge of those skilled in the art.

Claims

1. A phase-shift frequency modulation combined control LLC circuit for aerospace use, characterized in that: Including voltage feedback module, high frequency starting module, phase shift processing module and frequency modulation module; The voltage feedback module has a positive input terminal connected to the voltage loop given voltage, and a negative input terminal as the voltage output terminal. The output voltage signal is collected and processed by proportional integral operation, and then output to the phase shift processing module and the frequency modulation module; at the same time, the voltage is outputted at a specified frequency according to the frequency modulation signal sent by the frequency modulation module; The high-frequency starting module completes power-on after receiving the starting voltage, determines the starting frequency according to the level status of the connection point of the high-frequency starting module and the frequency modulation module, and completes the circuit startup; The frequency modulation module receives the voltage signal sent by the voltage feedback module and the current signal sent by the phase shift processing module, determines the output voltage of the frequency modulation module according to the two types of signals received, adjusts the circuit operating frequency based on the relationship between the output voltage and the received current signal, and sends the frequency modulation signal to the voltage feedback module; The phase shift processing module divides the voltage signal sent by the voltage feedback module, and then adjusts the phase shift angle through the phase shift control chip according to the input voltage to adjust the current signal output to the frequency modulation module, and outputs the current signal to the frequency modulation module.

2. The phase-shift frequency modulation combined control LLC circuit for aerospace use according to claim 1, characterized in that: The voltage feedback module includes an operational amplifier chip U1, a resistor R7, a resistor R8, and a capacitor C2; The positive input terminal of the operational amplifier chip U1 is connected to the given terminal Vref of the voltage loop, and the negative input terminal is connected to the output voltage Vo through the resistor R7. The negative input terminal is also connected to the connection point of R7 and one end of the resistor R8. The other end of the resistor R8 is connected to one end of the capacitor C2, and the other end of the capacitor C2 is connected to the output terminal of the operational amplifier chip U1.

3. The phase-shift frequency modulation combined control LLC circuit for aerospace use according to claim 1, characterized in that: The high-frequency starting module includes a transistor V3, a diode V4, a capacitor C3, a resistor R3, a resistor R5, and a resistor R6; The collector of the transistor V3 is connected to the anode of the voltage regulator Vz, the base of the transistor V3 is connected to the anode of the diode V4 and one end of the resistor R5, the cathode of the diode V4 is connected to one end of the resistor R6, the other end of the resistor R6 is connected to the other end of the resistor R5 and then to the positive end of the external power supply, one end of the capacitor C3 is connected to the base of the transistor V3, the other end of the capacitor C3 is connected to the emitter of the transistor V3 and then to the power supply ground, one end of the resistor R3 is connected to the collector of the transistor V3, and the other end is connected to the power supply ground.

4. The phase-shift frequency modulation combined control LLC circuit for aerospace use according to claim 1, characterized in that: The phase shift processing module includes a phase shift control chip U3, a resistor R1, a resistor R2, a capacitor C1, and a resistor RT; The voltage feedback loop output voltage Vfb is connected through a voltage divider of resistors R1 and R2, and the voltage divider connection point is connected to the chip EA pin of the phase shift control chip U3. The EA- pin of the phase shift control chip U3 is connected to the EAout pin. One end of the capacitor C1 and the resistor RT are connected to the power supply ground. The Frequency pin of the phase shift control chip U3 is connected to the other end of the capacitor C1, and the common connection point is connected to the frequency modulation module.

5. The phase-shift frequency modulation combined control LLC circuit for aerospace use according to claim 1, characterized in that: The frequency modulation module includes an operational amplifier chip U2, a diode V1, a diode V2, a diode Vz, and a resistor R4; The positive input terminal of the operational amplifier chip U2 is connected to the collector of the transistor V3, the negative input terminal and the common point of the output terminal are connected to the cathode of the diode V2, the anode of the diode V2 is connected to one end of the resistor R4, and the other end of R4 is connected to the Frequency pin of the phase shift control chip U3; the diode V1 is connected to the cathode of the diode Vz, the anode of the diode Vz is connected to the positive input terminal of the operational amplifier chip U2, and the anode of the diode V1 is connected to the output terminal of the operational amplifier chip U1.

6. The phase-shift frequency modulation combined control LLC circuit for aerospace use according to claim 5, characterized in that: After the output voltage Vfb of the voltage feedback module is connected to the anode of the diode V1 in the frequency modulation module, the common point is connected to one end of the circuit R1 in the phase shift processing module; the collector of the transistor V3 in the high-frequency starting module is connected to the positive input end of the operational amplifier chip U2 in the frequency modulation module; one end of the resistor R4 in the frequency modulation module is connected to the Frequency pin of the phase shift control chip U3 in the phase shift processing module.

7. A phase-shift frequency modulation combined control LLC circuit for aerospace use according to claim 6, characterized in that: The phase shift control chip U3 adopts UC1875 chip, which realizes circuit frequency conversion by changing the output current of the Equency pin and transmitting it to the frequency modulation module; the phase shift control chip U3 adjusts the phase shift angle by changing the voltage at both ends of the EAOUT pin, and controls and adjusts the current signal output to the frequency modulation module according to the phase shift angle.

8. A phase-shift frequency modulation combined control LLC circuit for aerospace use according to claim 1, characterized in that: The frequency modulation module adjusts the circuit operating frequency based on the relationship between the output voltage and the received current signal, and determines the circuit operating mode according to the adjusted operating frequency, including PS mode and VF mode; when the input voltage of the phase shift processing module is lower than the preset value, the circuit works in VF mode; when the input voltage of the phase shift processing module is higher than the preset value, the circuit works in PS mode.

9. A phase-shift frequency modulation combined control LLC circuit for aerospace use according to claim 8, characterized in that: In the PS mode, when the circuit output voltage Vo is higher than the voltage loop given end Vref, the voltage value Vfb at the output end of the voltage feedback module decreases; the voltage value Vea at the input end of the phase shift processing module decreases, and the output duty cycle of the phase shift control chip U3 decreases to control the circuit output voltage Vo to achieve voltage stabilization control; When the voltage value Vfb at the output of the voltage feedback module decreases, the voltage regulator tube Vz is not broken down and cannot enter the VF mode; In the VF mode, when the circuit output voltage Vo is lower than the voltage loop given end Vref, the voltage value Vfb at the output end of the voltage feedback module increases; the voltage value Vea at the input end of the phase shift processing module increases, and the output duty cycle of the phase shift control chip U3 increases to control the circuit output voltage Vo to increase and realize voltage stabilization control; The voltage value Vfb at the output end of the voltage feedback module increases, the voltage regulator tube Vz is broken down, and the input positive terminal voltage of the operational amplifier chip U2 is Ufb-Uvz. When the input positive terminal voltage Ufb-Uvz is greater than the output voltage of the Frequency pin, the output drive frequency of the control chip U3 is reduced to increase the LLC converter resonant cavity gain.

10. A phase-shift frequency modulation combined control LLC circuit for aerospace use according to claim 9, characterized in that: When the PS mode is in transition to the VF mode, the initial state of the circuit is the PS mode. When the voltage value Vfb at the output end of the voltage feedback module rises to the breakdown voltage of the diode V1 and the diode Vz, the diode Vz breaks down and conducts. The voltage value of the transistor V3 is the difference between the voltage value at the output end of the voltage feedback module and the breakdown voltage value. The output current I4 of the phase shift processing module decreases, so that the output current IF of the Frequency pin decreases to reduce the circuit frequency. The circuit state changes from the PS mode to the VF mode. In the transition state from VF mode to PS mode, the initial state of the circuit is VF mode, the input voltage Vea of ​​the phase shift processing module is greater than the preset value, and the voltage feedback module controls the output voltage value Vfb to reduce the voltage to increase the output current I4 of the phase shift processing module. The increase in the output current I4 of the phase shift processing module increases the output current IF of the Frequency pin to increase the circuit frequency, and the circuit state enters the PS mode from the VF mode until the input voltage Vea of ​​the phase shift processing module is less than the preset value.

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