CN114337344A - Control method based on self-adaptive hybrid rectification multi-switch resonant LLC converter - Google Patents

Abstract

The invention provides a control method based on a self-adaptive hybrid rectification multi-switch resonant LLC converter. Its characterized in that simple structure, the required components and parts quantity is few under the condition of realizing the same wide output voltage scope, includes: the device comprises a capacitor unit, an inverter network, a resonance network, a high-frequency transformer, a rectifier network and a pulse signal generating unit. The control method adopts fixed-frequency Asymmetric Pulse Width (APWM) modulation, the switching frequency is fixed and equal to the resonant frequency, the conduction duty ratio of a switching tube is changed only through a pulse signal generating unit, the smooth switching of a full-bridge inverter circuit, a half-bridge inverter circuit, a full-bridge rectifier circuit and a voltage-multiplying rectifier circuit is realized, and the ultra-wide output voltage regulation is further realized. Meanwhile, the circulating current in the circuit is small, the control is simple, and the size miniaturization of the transformer is facilitated.

Description

Control method based on self-adaptive hybrid rectification multi-switch resonant LLC converter

Technical Field

The invention belongs to the field of power electronics, and particularly relates to a control method based on an adaptive hybrid rectification multi-switch resonant LLC converter.

Background

In recent years, with the increasing prominence of problems such as energy crisis and environmental pollution, applications of clean energy such as new energy automobiles, wind power generation, and photovoltaics have been developed, and among them, DC-DC converters having electrical isolation play an essential role in the above fields. Currently, high conversion efficiency and high power density are the main development directions of DC-DC converters, and how to meet the voltage regulation requirements of the DC-DC converters in different application occasions, high-frequency and high-efficiency operation, and volume miniaturization are the main research hotspots.

Among a series of dc-dc converters, the LLC resonant converter has recently become a hot point of research in the field of power electronics due to its advantages of simple structure, excellent soft switching performance, high switching frequency, high power density, and the like. However, in the application occasions (such as electric vehicle charger, lighting power supply, distributed power distribution and the like) requiring wide output voltage, the LLC resonant converter of pulse frequency modulation is limited by the switching frequency because of the voltage gain, and the wide voltage regulation range is difficult to realize. Also, the use of frequency modulation complicates the converter design. Particularly, when the switching frequency is far away from the resonant frequency, a large circulating current exists in the circuit, the switching tube cannot realize zero voltage turn-off (ZVS), the rectifying-side diode cannot realize zero current turn-on (ZCS), the switching loss of the turn-on loss of the converter is increased undoubtedly, and the energy conversion efficiency is low. In addition, when the switching power supply operates at a wide switching frequency, the low switching frequency corresponds to the weight of the volume of the large transformer, which is contrary to the volume miniaturization design of the converter, and the development of the switching power supply towards high power density is hindered.

Disclosure of Invention

The invention mainly aims to overcome the defects in the prior art, provides a five-switch double-resonance LLC resonant converter circuit with a self-adaptive hybrid rectification structure and a control method thereof for wide output voltage application occasions, and aims to reduce the switch loss, the conduction loss and the transformer volume while realizing the wide voltage gain of the converter.

In a first aspect, the invention provides a self-adaptive hybrid rectification multi-switch resonant LLC converter, which can implement a self-adaptive switching circuit rectification mode, reduce the number and size of components, and implement a wider output voltage gain range.

The technical scheme of the system is that the self-adaptive mixed rectification multi-switch resonance LLC converter is characterized by comprising the following steps: the device comprises a capacitance unit (I), an inverter network (II), a resonance network (III), a high-frequency transformer (IV), a rectifier network (V) and a pulse signal generation unit (VI).

The concrete components are as follows:

the capacitor unit (I) comprises a direct current input power supply U_inA first input capacitor C_in1A second input capacitor C_in2；

The inverter network (II) comprises a first switching tube S₁A second switch tube S₂A third switch tube S₃And a fourth switching tube S₄；

The resonant network (III) comprises a resonant capacitor C_rResonant inductor L_rFirst excitation inductance L_m1Second excitation inductance L_m2。

The high-frequency transformer (IV) comprises a first high-frequency transformer T₁A second high-frequency transformer T₂。

The rectifier network (V) comprises a first rectifier diode D₁A second rectifying diode D₂A third rectifying diode D₃A fourth rectifying diode D₄Auxiliary fifth switch tube S₅First filter capacitor C_O1A second filter capacitor C_O2Equivalent resistive load R₀；

In the pulse signal generating unit (VI), the PWM output interface of the controller is respectively connected with the first switch tube S in the inverter network (II)₁A second switch tube S₂A third switch tube S₃And a fourth switching tube S₄And an auxiliary fifth switching tube S in the rectifier network (V)₅A gate electrode of (2).

A first input capacitance C of the capacitance unit (I)_in1And a second input capacitor C_in2Are connected in series; the first input capacitor C_in1The anode of the power supply is connected with a direct current input power supply U_inPositive pole of (1), first input capacitance C_in1Negative pole of the first capacitor is connected with C of the second capacitor_in2Positive electrode, C of the second capacitance_in2Negative pole connected with DC input power supply U_inThe negative electrode of (1);

wherein the first switch tube S₁And the second switch tube S₂The first switch tube S is connected in series end to end₁Drain electrode of the power supply is connected with the direct current input power supply U_inThe second switching tube S₂Is connected with the first switch tube S₁The second switch tube S₂Is connected with the DC input power supply U_inThe negative electrode of (1). The third switch tube S₃And the fourth switching tube S₄The first switching tube and the second switching tube are connected in series end to end, and the third switching tube S₃Is connected with the first switch tube S₁The fourth switching tube S₄Is connected with the third switching tube S₃Source electrode of, the fourth switching tube S₄Is connected with the second switch tube S₂Of the substrate.

The resonant network (III) is symmetrical up and down, and the resonant inductance L_rFirst excitation inductance L_m1A second excitation inductance L_m2The three nodes have the same node;

the left end of the resonant capacitor Cr is connected with the serial common end of the third switch tube S3 and the fourth switch tube S4, and the resonant capacitor CrThe right end is connected with the resonance inductor Lr in series and then respectively connected with the first excitation inductor L_m1And said second excitation inductance L_m2Connected, the first excitation inductance L_m1The other end is connected with the series common end of the first switch tube S1 and the second switch tube S2, and the second excitation inductor L_m2The other end of the first input capacitor C_in1And the second input capacitor C_in2Are connected to a common terminal.

The first excitation inductance L_m1And the first high-frequency transformer T₁The primary side windings of the second excitation inductor L are connected in parallel, and the second excitation inductor L_m2And the second high-frequency transformer T₂The primary windings of (a) are connected in parallel.

The first excitation inductance L_m1Equal to the second excitation inductance L_m2；

The first rectifying diode D₁And the second rectifying diode D₂Is connected in series with the negative pole of the third rectifying diode D₃And the fourth rectifying diode D₄Is connected in series, the first rectifying diode D₁Is connected to the third rectifier diode D₃The negative electrode of (2), the second rectifier diode D₂Is connected with the fourth rectifying diode D₄The positive electrode of (1). The first rectifying diode D₁Negative pole and the third rectifier diode D₃The common end of the negative electrode is connected with the first filter capacitor C_O1The second rectifying diode D₂An anode and the fourth rectifying diode D₄The common end of the anode is connected with the filter capacitor C_O2The negative electrode of (1); the first filter capacitor C_O1Negative pole and the second filter capacitor C_O2The positive electrodes are connected in series; the equivalent resistive load R₀And a first filter capacitor C_O1A second filter capacitor C_O2The series branches formed by the filter capacitors are connected in parallel.

The first high-frequency transformer T₁A positive electrode on the primary side and the second high-frequency transformer T₂A primary side positive electrode connection; the first high-frequency transformer T₁Two timesThe side anode is connected with the first rectifier diode D₁And said second rectifying diode D₂The first high-frequency transformer T₁Secondary side cathode and the second high-frequency transformer T₂Secondary side positive electrodes connected in series, wherein the second high frequency transformer T₂The cathode of the secondary side is connected with the third rectifier diode D₃A fourth rectifying diode D₄To the public terminal.

The first high-frequency transformer T₁And the second high-frequency transformer T₂The coil turns ratios of (a) and (b) are equal;

the auxiliary fifth switch tube S₅Is connected to the third rectifying diode D₃An anode and the fourth rectifying diode D₄A common terminal of the negative electrode, the auxiliary fifth switching tube S₅Is connected with the first filter capacitor C_O1Negative pole, the second filter capacitor C_O2A common terminal of the positive electrode.

A second aspect provides a control method, which is characterized in that fixed-frequency Asymmetric Pulse Width (APWM) modulation is adopted, the switching frequency is fixed and equal to the resonant frequency, the control is simple, and the miniaturization of the transformer volume is facilitated.

Under the control method, the pulse signal generating unit (VI) respectively sends the pulse signals to the first switch tube S₁A second switch tube S₂A third switch tube S₃And a fourth switching tube S₄The gate outputs a pulse signal with complementary duty ratio, and the inversion network (II) inverts the direct current input voltage into square wave voltage. Wherein, the first switch tube S₁A second switch tube S₂The working time of the third switch tube S is fixed to be half of a conduction period₃The working time length in one period, namely the duty ratio D, can be changed within the range of 0-D_max. The method comprises the following specific steps:

the method comprises the following steps: the pulse signal generating unit (VI) supplies a first switch tube S₁And a fourth switching tube S₄A gate pole applying a high-level pulse signal, a first switching tube S₁And a fourth switching tube S₄The upper half part of the input voltage V of the resonant network (III) forms a full-bridge inverter circuit_ab＝U_inA second input capacitor C_in2And a fourth switching tube S₄The lower half part of the resonant network (III) forms an input voltage V of a half-bridge inverter circuit_cb＝U _in2; at this time, the pulse signal generating unit (VI) is applied to the auxiliary fifth switching tube S₅The pulse signal of the gate pole is low level, the rectifier circuit (V) works in a mixed state of a full-bridge rectification mode and a voltage-multiplying rectification mode, and the alternating current transmitted by the secondary side of the transformer is converted into direct current;

step two: the pulse signal generating unit (VI) supplies a second switch tube S₂And a fourth switching tube S₄The gate pole applies high-level pulse signal, the upper half input voltage V of resonant network (III)_ab0, second input capacitance C_in2And a fourth switching tube S₄The lower half part of the resonant network (III) forms an input voltage V of a half-bridge inverter circuit_cb＝U _in2; at this time, the pulse signal generating unit (VI) is applied to the auxiliary fifth switching tube S₅The pulse signal of the gate pole is still low level, the rectifier circuit (V) works in a full-bridge rectification mode, and the alternating current transmitted by the secondary side of the transformer is converted into direct current;

step three: the pulse signal generating unit (VI) supplies a second switch tube S₂A third switch tube S₃A gate pole applying a high-level pulse signal, a second switching tube S₂A third switch tube S₃The upper half part of the input voltage V of the resonant network (III) forms a full-bridge inverter circuit_ab＝-U_inA first input capacitor C_in1A second switch tube S₂The lower half part of the resonant network (III) forms an input voltage V of a half-bridge inverter circuit_cb＝-U _in2; at this time, the pulse signal generating unit (VI) is applied to the auxiliary fifth switching tube S₅The pulse signal of the gate pole is high level, the rectifier circuit (V) works in a voltage-multiplying rectification mode, and the alternating current transmitted by the secondary side of the transformer is converted into direct current;

under the control method, in the primary side control, the third switching tube S is changed₃The duration of operation in one cycle, i.e. duty cycle D, causing the first switch to be actuatedPipe S₁A second switch tube S₂Series branch and third switch tube S₃And a fourth switching tube S₄The full-bridge inverter circuit formed by connecting the series branches in parallel is gradually changed into a full-bridge inverter circuit from a half-bridge inverter circuit, and the third switching tube S₃And a fourth switching tube S₄Series branch and first input capacitor C_in1A second input capacitor C_in2The auxiliary half-bridge inverter circuit formed by the series branch is gradually changed from being not connected into a complete half-bridge inverter circuit, wherein D is more than or equal to 0 and less than or equal to D_max(ii) a Auxiliary fifth switch tube S₅The control of (V) realizes the self-adaptive rectification of the rectification network (V), and further realizes the wide output voltage regulation range.

The technical difference between the invention and the prior art is that all switch tubes adopt a fixed-frequency APWM control strategy, the full-bridge inverter circuit (II-1) of the first part can realize flexible switching from a half bridge to a full bridge, and a wider output voltage regulation range is obtained through smooth switching of a secondary full-bridge rectification mode, a full-bridge/voltage-multiplying mixed rectification mode and a voltage-multiplying rectification mode. In the control method, the switching frequencies of all the switching tubes are equal, the switching frequencies are fixed and equal to the resonant frequency, the switching tubes always work at the optimal efficiency point, the design requirements on magnetic elements such as an excitation inductor and a transformer are low, and the design of the converter with small volume and high power density are facilitated.

The invention realizes the capacity of adjusting the ultra-wide output voltage of the LLC converter, adopts fixed-frequency APWM control, is beneficial to the design of the converter, and does not need to consider the problems of low efficiency, low power density and the like caused by wide switching frequency.

Under the fixed frequency control method, the circulating current in the circuit can be reduced by adopting the excitation inductor with larger capacity, the larger switching frequency is beneficial to reducing the volume and the weight of the resonance inductor and the isolation transformer, and the power density of the LLC converter is improved.

Auxiliary fifth switch tube S₅And a third switching tube S₃The control signals are the same, and the control is simple.

Only one auxiliary fifth switch tube S is required to be added₅Can realize the secondary side rectification structureThe self-adaptive switching of the switching circuit further realizes the smooth switching from the low output voltage to the high output voltage, and the number of adopted devices is less.

Smooth switching from the low output voltage to the high output voltage can be achieved only by changing the duty D ratio without changing the switching frequency.

Drawings

FIG. 1: a schematic diagram of a hybrid rectification five-switch double-resonance LLC converter structure;

FIG. 2: an equivalent schematic diagram of the LLC converter at low output voltage;

FIG. 3: an equivalent schematic diagram of the LLC converter at high output voltage;

FIG. 4: a schematic diagram of control pulses when the LLC converter switches from a low output voltage to a high output voltage;

FIG. 5: a voltage gain G and duty ratio D relation curve of the LLC converter;

FIG. 6: two resonant network exciting current and resonant current curves of the converter at different duty ratios;

FIG. 7: soft switching waveforms of a primary side and a secondary side of the down converter with different duty ratios are obtained;

FIG. 8: the example down-converter output voltage curve was designed.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. After reading the teaching of the present invention, the skilled in the art can make various changes or modifications to the invention, and these equivalents also fall within the scope of the claims appended to the present application.

The first embodiment of the present invention is as follows:

a five-switch double-resonance LLC resonant converter with a hybrid rectification structure is characterized in that a primary side inversion network (II) of the structure can work in multiple inversion states, resonance networks (III) which are symmetrical up and down share a resonance inductor and a resonance capacitor, and a secondary side rectification network (V) can realize a self-adaptive switching circuit rectification mode only according to the conduction state of a primary side switch tube and an auxiliary switch on the secondary side, so that the number and the size of components are reduced, and a wider output voltage gain range is realized.

The technical scheme of the system is a five-switch double-resonance LLC resonant converter with a hybrid rectification structure, which is characterized by comprising the following steps of: the device comprises a capacitance unit (I), an inverter network (II), a resonance network (III), a high-frequency transformer (IV), a rectifier network (V) and a pulse signal generation unit (VI).

The concrete components are as follows:

the capacitor unit (I) comprises a direct current input power supply U_inA first input capacitor C_in1A second input capacitor C_in2；

The DC input power supply U_inIs selected to be U_in＝100V；

The first input capacitor C_in1Is selected from the group consisting of_in1＝120uF；

The second input capacitor C_in2Is selected from the group consisting of_in2＝120uF；

The inverter network (II) comprises a first switching tube S₁A second switch tube S₂A third switch tube S₃And a fourth switching tube S₄；

The first switch tube S₁The type of the strain is AUIRFS 4115-7P;

the second switch tube S₂The type of the strain is AUIRFS 4115-7P;

the third switch tube S₃The type of the strain is AUIRFS 4115-7P;

the fourth switch tube S₄The type of the strain is AUIRFS 4115-7P;

the resonance networks (III) which are symmetrical up and down share one resonance capacitor C_rResonant inductor L_rWherein:

the resonant capacitor C_r147 nF;

the resonance inductor L_rThe type selection of (1) is 17.2 mu H;

the first excitation inductance L_m1The type selection of (1) is 172 muH;

the second excitation inductance L_m2The type selection of (1) is 172 muH;

the high-frequency transformer (IV) comprises a first high-frequency transformer T₁A second high-frequency transformer T₂。

The first high-frequency transformer T₁Is PQ 3220;

the second high-frequency transformer T₂Is PQ 3220;

the rectifier network (V) comprises a first rectifier diode D₁A second rectifying diode D₂A third rectifying diode D₃A fourth rectifying diode D₄Auxiliary fifth switch tube S₅First filter capacitor C_O1A second filter capacitor C_O2Equivalent resistive load R₀；

The first rectifying diode D₁Is IPP045N 10N;

the second rectifying diode D₂Is IPP045N 10N;

the third rectifying diode D₃Is IPP045N 10N;

the fourth rectifying diode D₄Is IPP045N 10N;

the auxiliary fifth switch tube S₅The type of the strain is AUIRFS 4115-7P;

the first filter capacitor C_O1The selection type of (A) is RMJ-MT;

the second filter capacitor C_O2The selection type of (A) is RMJ-MT;

the equivalent resistive load R₀The type selection of (1) is GLE-RXLG;

the type of the pulse signal generation unit (VI) controller is STM32H750 VB.

A first input capacitance C of the capacitance unit (I)_in1And a second input capacitor C_in2Are connected in series; the first input capacitor C_in1The anode of the power supply is connected with a direct current input power supply U_inPositive pole of (1), first input capacitance C_in1Negative pole of the first capacitor is connected with C of the second capacitor_in2Positive electrode, C of the second capacitance_in2Negative pole connected with DC input power supply U_inThe negative electrode of (1);

wherein the first switch tube S₁And the second switch tube S₂The first switch tube S is connected in series end to end₁Drain electrode of the power supply is connected with the direct current input power supply U_inThe second switching tube S₂Is connected with the first switch tube S₁The second switch tube S₂Is connected with the DC input power supply U_inThe negative electrode of (1). The third switch tube S₃And the fourth switching tube S₄The first switching tube and the second switching tube are connected in series end to end, and the third switching tube S₃Is connected with the first switch tube S₁The fourth switching tube S₄Is connected with the third switching tube S₃Source electrode of, the fourth switching tube S₄Is connected with the second switch tube S₂Of the substrate.

The resonant network (III) is symmetrical up and down, and the resonant inductance L_rFirst excitation inductance L_m1A second excitation inductance L_m2The three nodes have the same node;

the left end of the resonant capacitor Cr is connected with the serial common end of the third switch tube S3 and the fourth switch tube S4, and the right end of the resonant capacitor Cr is connected with the resonant inductor Lr in series and then is respectively connected with the first excitation inductor L_m1And said second excitation inductance L_m2Connected, the first excitation inductance L_m1The other end is connected with the series common end of the first switch tube S1 and the second switch tube S2, and the second excitation inductor L_m2The other end of the first input capacitor C_in1And the second input capacitor C_in2Are connected to a common terminal.

The first excitation inductance L_m1And the first high-frequency transformer T₁The primary side windings of the second excitation inductor L are connected in parallel, and the second excitation inductor L_m2And the second high-frequency transformer T₂The primary windings of (a) are connected in parallel.

The first excitation inductance L_m1Equal to the second excitation inductance L_m2；

The first rectifying diode D₁And the second rectifying diode D₂Is connected in series with the negative pole of the third rectifying diode D₃And the fourth rectifying diode D₄Is connected in series, the first rectifying diode D₁Is connected to the third rectifier diode D₃The negative electrode of (2), the second rectifier diode D₂Is connected with the fourth rectifying diode D₄The positive electrode of (1). The first rectifying diode D₁Negative pole and the third rectifier diode D₃The common end of the negative electrode is connected with the first filter capacitor C_O1The second rectifying diode D₂An anode and the fourth rectifying diode D₄The common end of the anode is connected with the filter capacitor C_O2The negative electrode of (1); the first filter capacitor C_O1Negative pole and the second filter capacitor C_O2The positive electrodes are connected in series; the equivalent resistive load R₀And a first filter capacitor C_O1A second filter capacitor C_O2The series branches formed by the filter capacitors are connected in parallel.

The first high-frequency transformer T₁A positive electrode on the primary side and the second high-frequency transformer T₂A primary side positive electrode connection; the first high-frequency transformer T₁The secondary side anode is connected with the first rectifier diode D₁And said second rectifying diode D₂The first high-frequency transformer T₁Secondary side cathode and the second high-frequency transformer T₂Secondary side positive electrodes connected in series, wherein the second high frequency transformer T₂The cathode of the secondary side is connected with the third rectifier diode D₃A fourth rectifying diode D₄To the public terminal.

The first high-frequency transformer T₁And the second high-frequency transformer T₂The coil turns ratios of (a) and (b) are equal;

the auxiliary fifth switch tube S₅Is connected to the third rectifying diode D₃An anode and the fourth rectifying diode D₄A common terminal of the negative electrode, the auxiliary fifth switching tube S₅Is connected with the first filter capacitor C_O1Negative pole, the second filter capacitor C_O2A common terminal of the positive electrode.

The PWM output interfaces of the controller in the pulse signal generating unit (VI) are respectively connected with a first switching tube S in the inversion network (II)₁A second switch tube S₂A third switch tube S₃And a fourth switching tube S₄And an auxiliary fifth switching tube S in the rectifier network (V)₅A gate electrode of (2).

The second aspect provides a control method of the hybrid rectification type five-switch double-resonance converter, which is characterized in that fixed-frequency Asymmetric Pulse Width (APWM) modulation is adopted, the switching frequency is fixed and equal to the resonance frequency, the control is simple, and the size of the transformer is favorably miniaturized.

Under the control method, the DSP controller respectively sends the signals to the first switch tubes S₁A second switch tube S₂A third switch tube S₃And a fourth switching tube S₄The gate outputs a pulse signal with complementary duty ratio, and the inversion network (II) inverts the direct current input voltage into square wave voltage. Wherein, the first switch tube S₁A second switch tube S₂The working time of the third switch tube S is fixed to be half of a conduction period₃The working time length in one period, namely the duty ratio D, can be changed within the range of 0-D_max. The method comprises the following specific steps:

the method comprises the following steps: the pulse signal generating unit (VI) supplies a first switch tube S₁And a fourth switching tube S₄A gate pole applying a high-level pulse signal, a first switching tube S₁And a fourth switching tube S₄The upper half part of the input voltage V of the resonant network (III) forms a full-bridge inverter circuit_ab＝U_inA second input capacitor C_in2And a fourth switching tube S₄The lower half part of the resonant network (III) forms an input voltage V of a half-bridge inverter circuit_cb＝U _in2; at this time, the pulse signal generating unit (VI) is applied to the auxiliary fifth switching tube S₅The pulse signal of the gate pole is low level, the rectifier circuit (V) works in a mixed state of a full-bridge rectification mode and a voltage-multiplying rectification mode, and the alternating current transmitted by the secondary side of the transformer is converted into direct current;

step two: the pulse signal generating unit (VI) is connected to the secondTwo switching tubes S₂And a fourth switching tube S₄The gate pole applies high-level pulse signal, the upper half input voltage V of resonant network (III)_ab0, second input capacitance C_in2And a fourth switching tube S₄The lower half part of the resonant network (III) forms an input voltage V of a half-bridge inverter circuit_cb＝U _in2; at this time, the pulse signal generating unit (VI) is applied to the auxiliary fifth switching tube S₅The pulse signal of the gate pole is still low level, the rectifier circuit (V) works in a full-bridge rectification mode, and the alternating current transmitted by the secondary side of the transformer is converted into direct current;

step three: the pulse signal generating unit (VI) supplies a second switch tube S₂A third switch tube S₃A gate pole applying a high-level pulse signal, a second switching tube S₂A third switch tube S₃The upper half part of the input voltage V of the resonant network (III) forms a full-bridge inverter circuit_ab＝-U_inA first input capacitor C_in1A second switch tube S₂The lower half part of the resonant network (III) forms an input voltage V of a half-bridge inverter circuit_cb＝-U _in2; at this time, the pulse signal generating unit (VI) is applied to the auxiliary fifth switching tube S₅The pulse signal of the gate pole is high level, the rectifier circuit (V) works in a voltage-multiplying rectification mode, and the alternating current transmitted by the secondary side of the transformer is converted into direct current;

under the control method, in the primary side control, the third switching tube S is changed₃The working time length in one period, namely the duty ratio D, enables the first switch tube S₁A second switch tube S₂Series branch and third switch tube S₃And a fourth switching tube S₄The full-bridge inverter circuit formed by connecting the series branches in parallel is gradually changed into a full-bridge inverter circuit from a half-bridge inverter circuit, and the third switching tube S₃And a fourth switching tube S₄Series branch and first input capacitor C_in1A second input capacitor C_in2The auxiliary half-bridge inverter circuit formed by the series branch is gradually changed from being not connected into a complete half-bridge inverter circuit, wherein D is more than or equal to 0 and less than or equal to D_max(ii) a Auxiliary fifth switch tube S₅The control of (V) realizes the self-adaptive rectification of the rectification network (V), and further realizes the wide output voltage regulation range.

Under the control method, in the primary side control, the third switching tube S is changed₃The working time length in one period, namely the duty ratio D, enables the first switch tube S₁A second switch tube S₂Series branch and third switch tube S₃And a fourth switching tube S₄The full-bridge inverter circuit formed by connecting the series branches in parallel is gradually changed into a full-bridge inverter circuit from a half-bridge inverter circuit, and the third switching tube S₃And a fourth switching tube S₄Series branch and first input capacitor C_in1A second input capacitor C_in2The auxiliary half-bridge inverter circuit formed by the series branch is gradually changed from being not connected into a complete half-bridge inverter circuit, wherein D is more than or equal to 0 and less than or equal to D_max(ii) a Auxiliary fifth switch tube S₅The control of the rectifier network (V) realizes the self-adaptive rectification of the rectifier network (V), and further realizes the wide output voltage regulation range of 100V-550V.

The second embodiment of the present invention is as follows:

the proposed five-switch dual-resonant network LLC resonant converter circuit with hybrid rectification structure and control method are shown in fig. 1. Wherein, U_inA first input capacitor C of the capacitor unit (I) for providing stable input voltage for a direct current input power supply and an inverter network_in1And a second input capacitor C_in2Connected in series and respectively carrying half of the input voltage. First switch tube S₁And a second switching tube S₂A third switching tube S connected in series end to end₃And a fourth switching tube S₄Are connected in series end to end. Wherein, the third switch tube S₃And a fourth switching tube S₄Common-end connected resonance capacitor C_rResonant inductor L_rFirst excitation inductance L_m1A second excitation inductance L_m2The upper and lower symmetrical resonant networks (III) are formed by connecting in series; a first high-frequency transformer T₁A second high-frequency transformer T₂The transformer has the functions of electrical isolation and electric energy transmission, and the transformation ratios are n. Secondary side rectifier diode D₁～D₄Form a full-bridge rectifier network, assist the fifthSwitch tube S₅The function of controlling the rectification mode is realized; the two series filter capacitors play a role in filtering, and simultaneously clamp the voltages at the two ends of the diode, so that the voltage stress at the two ends of the diode is reduced. R₀Is an equivalent resistive load. The PWM output interface of the DSP controller of the pulse signal generating unit (VI) is respectively connected with a first switch tube S in the inverter network (II)₁A second switch tube S₂A third switch tube S₃And a fourth switching tube S₄And an auxiliary fifth switching tube S in the rectifier network (V)₅A gate electrode of (2). The voltage current reference direction in the circuit is shown in figure 1.

The equivalent circuit of the converter operating in low voltage mode is shown in fig. 2. First switch tube S₁And a second switching tube S₂At maximum duty cycle D_maxComplementary conducting, third switch tube S₃The duty ratio D of is 0, and the fourth switching tube S₄The pulse signal of (a) is stabilized to a high level in one period, and a second high-frequency transformer T₂The first switch tube S can not transmit energy to the secondary side₁A second switch tube S₂And a fourth switching tube S₄The half-bridge inverter circuit works, and the lower half part of the resonant network (III) does not transfer energy to a load. Auxiliary fifth switch tube S₅And the whole period is disconnected and not operated, namely the duty ratio D is equal to 0, and the rectification network (V) is operated in a full-bridge mode. At this time, the converter is equivalent to a half-bridge LLC resonant converter circuit, and the corresponding output voltage is the lowest, U_0-min＝100V。

The converter operates in a high voltage mode and the converter equivalent circuit is shown in figure 3. First switch tube S₁And a second switching tube S₂At maximum duty cycle D_maxComplementary conducting, third switch tube S₃And a fourth switching tube S₄Also at maximum duty cycle D_maxComplementary conduction, the first switching tube S₁A second switch tube S₂A third switch tube S₃And a fourth switching tube S₄Working in a full-bridge inverter circuit, the third switching tube S₃And a fourth switching tube S₄A first input capacitor C_in1A second input capacitor C_in2Operating at half-bridgeInverter circuit corresponding to the auxiliary fifth switch S₅Continuously conducting in the whole period, wherein the duty ratio D is the maximum duty ratio D_maxI.e. half-cycle auxiliary fifth switch S₅A fifth switch tube S with positive conduction and half period assistance₅The body diode (V) is freewheeling and the rectifier network (V) operates in a voltage-doubling rectifier mode. At this time, the corresponding output voltage is the highest, U_0-max＝550V。

When the converter output voltage is switched from low voltage to high voltage, the converter control signal is as shown in fig. 4. First switch tube S₁And a second switching tube S₂Maximum duty cycle D_maxAnd conducting complementarily. Third switch tube S₃And a fourth switching tube S₄Complementary conducting, third switch tube S₃The duty ratio of D is D, and the adjustment range of D is 0-D_max. Changing the third switching tube S₃The working time in one period, i.e. the duty ratio D, D is more than or equal to 0 and less than or equal to D_max) So that the first switch tube S₁A second switch tube S₂Series branch and third switch tube S₃And a fourth switching tube S₄The full-bridge inverter circuit formed by connecting the series branches in parallel is gradually changed into a full-bridge inverter circuit from a half-bridge inverter circuit, and the third switching tube S₃And a fourth switching tube S₄Series branch and first input capacitor C_in1A second input capacitor C_in2The auxiliary half-bridge inverter circuit formed by the series branch is gradually changed into a complete half-bridge inverter circuit by non-access. Meanwhile, a fourth switching tube S₄And a first switch tube S₁The phases are the same, i.e. the conduction time is the same, and the third switch tube S₃And a second switch tube S₂Is turned off at the same time to assist the fifth switch tube S₅And a third switch tube S₃With the same pulse signal. Under the control signal, when the duty ratio D is between 0 and D_maxWhen the voltage is changed within the range of (3), the input voltage V of the upper half part resonant network_abBy including U _in0 to include U_in、0、-U_inFinally becomes to include U_in、-U_inThe two-level voltage of (1). Input voltage V of lower half resonant network_cbBy U_inSingle-level voltage transformation of/2 to include U_in/2、-U_inA two-level voltage of/2. At the same time, the rectifier network (V) is in the auxiliary fifth switch tube S₅Under the action, the working time of the full-bridge rectification mode and the voltage-multiplying rectification mode in one period is automatically adjusted to be in proportion, the rectification mode is gradually transited from full-bridge rectification to voltage-multiplying rectification, and during the period, the full-bridge rectification mode and the voltage-multiplying rectification mode exist at the same time and work in a mixed mode. Output voltage U₀And gradually increases.

FIG. 5 shows the voltage gain (G, G ═ nU) of the LLC resonant converter in the invention₀/U_in) Duty cycle D. Wherein, the minimum voltage gain G of LLC resonant converter under the low output voltage mode is nU_0-min/U_in0.5, and the corresponding duty ratio D is 0; minimum voltage gain G-nU of LLC resonant converter in high-output voltage mode_0-max/U_in2.75, the corresponding duty cycle D is 0.5. As the duty ratio D increases, the voltage gain gradually increases, and the corresponding output voltage gradually increases.

FIG. 6 shows the excitation current i of the resonant network of the down-converter with different duty ratios D_lm1、i_lm2And a resonant current i_lr1、i_lr2The waveform of (a); the circulating current of the converter of the invention is almost 0 at different duty cycles, i.e. the resonant current i_LrWith excitation current i_LmAnd overlapping portions. Therefore, the converter can well reduce the conduction loss of the circulating current in the circuit and improve the working efficiency of the whole system.

Fig. 7 shows soft switching waveforms of zero-voltage turn-on (ZVS) of a primary side switching tube and zero-current turn-off (ZCS) of a secondary side rectifying diode of a down converter part with different duty ratios D. Wherein, V_gIndicating switching tube pulse signal, V_s1、V_s2Respectively represent a first switch tube S₁A second switch tube S₁Drain-source voltage, i_D1、i_D2Respectively indicating the flow through the first rectifier diode D₁A second rectifying diode D₂The current of (2). It is shown that the primary side switching tube and the secondary side rectifier diode respectively realize Zero Voltage Switching (ZVS) and zero power in the whole voltage regulation rangeAnd a current switch (ZCS) for reducing switching loss.

Fig. 8 is a variation curve of the output voltage of the converter obtained by the present invention for the design example. The input voltage is 160V, the resonant frequency of 100-550V is 100kHz, the rated output power is 1kW, and the resonant capacitor C_r147nF resonant inductor L_r17.2 muh, first excitation inductance, second excitation inductance L_m1＝L_m2172 muH, first and second input capacitors C_in1＝C_in2120 muF, a first output filter capacitor and a second output filter capacitor C_O1＝C_O24.7 muF, first high frequency transformer T₁A second high-frequency transformer T₂The number of turns of (a) is 0.8. As can be seen, the converter of the invention realizes smooth switching of the output voltage of the converter from 100V to 550V under the change of the duty ratio D.

In addition, the induced potential formula of the transformer is:

E＝4.44nfφ_m

wherein E is the effective value of the induced potential, f is the working frequency of the transformer, n is the number of turns, phi_mFor the main magnetic flux, the formula (1) shows that the higher the working frequency of the transformer is, the smaller the volume and weight of the transformer are, under the same magnetic core material and power capacity.

The switching frequency of the converter designed by the invention is fixed at 100kHz, and is twice of the lowest switching frequency of the traditional variable frequency control LLC resonant converter. Therefore, the volumes of the converter resonant inductor and the isolation transformer are greatly reduced, and the converter resonant inductor and the isolation transformer are suitable for occasions with wide output voltage and high power density.

The present invention has been described in terms of specific examples, which are provided to aid understanding of the invention and are not intended to be limiting. For a person skilled in the art to which the invention pertains, several simple deductions, modifications or substitutions may be made according to the idea of the invention. It will be understood by those skilled in the art that the foregoing is only a preferred embodiment of this invention, and is not intended to limit the invention, and that any modification, equivalent replacement, or improvement made within the spirit and principle of this invention should be included within the scope of protection of this invention.

Claims (1)

1. A control method based on an adaptive mixed rectification multi-switch resonance LLC converter is characterized in that,

the adaptive hybrid rectification multi-switch resonant LLC converter comprises: the device comprises a capacitance unit (I), an inverter network (II), a resonance network (III), a high-frequency transformer (IV), a rectifier network (V) and a pulse signal generation unit (VI);

the capacitor unit (I) comprises a direct current input power supply U_inA first input capacitor C_in1A second input capacitor C_in2；

The inverter network (II) comprises a first switching tube S₁A second switch tube S₂A third switch tube S₃And a fourth switching tube S₄；

The resonant network (III) comprises a resonant capacitor C_rResonant inductor L_rFirst excitation inductance L_m1Second excitation inductance L_m2；

The high-frequency transformer (IV) comprises a first high-frequency transformer T₁A second high-frequency transformer T₂；

The rectifier network (V) comprises a first rectifier diode D₁A second rectifying diode D₂A third rectifying diode D₃A fourth rectifying diode D₄Auxiliary fifth switch tube S₅First filter capacitor C_O1A second filter capacitor C_O2Equivalent resistive load R₀；

In the pulse signal generating unit (VI), the PWM output interface of the controller is respectively connected with the first switch tube S in the inverter network (II)₁A second switch tube S₂A third switch tube S₃And a fourth switching tube S₄And an auxiliary fifth switching tube S in the rectifier network (V)₅A gate electrode of (a);

a first input capacitance C of the capacitance unit (I)_in1And a second input capacitor C_in2Are connected in series; the first input capacitor C_in1The anode of the power supply is connected with a direct current input power supplyU_inPositive pole of (1), first input capacitance C_in1Negative pole of the first capacitor is connected with C of the second capacitor_in2Positive electrode, C of the second capacitance_in2Negative pole connected with DC input power supply U_inThe negative electrode of (1);

wherein the first switch tube S₁And the second switch tube S₂The first switch tube S is connected in series end to end₁Drain electrode of the power supply is connected with the direct current input power supply U_inThe second switching tube S₂Is connected with the first switch tube S₁The second switch tube S₂Is connected with the DC input power supply U_inThe negative electrode of (1); the third switch tube S₃And the fourth switching tube S₄The first switching tube and the second switching tube are connected in series end to end, and the third switching tube S₃Is connected with the first switch tube S₁The fourth switching tube S₄Is connected with the third switching tube S₃Source electrode of, the fourth switching tube S₄Is connected with the second switch tube S₂A source electrode of (a);

the resonant network (III) is symmetrical up and down, and the resonant inductance L_rFirst excitation inductance L_m1A second excitation inductance L_m2The three nodes have the same node;

the left end of the resonant capacitor Cr is connected with the serial common end of the third switch tube S3 and the fourth switch tube S4, and the right end of the resonant capacitor Cr is connected with the resonant inductor Lr in series and then respectively connected with the first excitation inductor L_m1And said second excitation inductance L_m2Connected, the first excitation inductance L_m1The other end is connected with the series common end of the first switch tube S1 and the second switch tube S2, and the second excitation inductor L_m2The other end of the first input capacitor C_in1And the second input capacitor C_in2Are connected with each other;

the first excitation inductance L_m1And the first high-frequency transformer T₁The primary side windings of the second excitation inductor L are connected in parallel, and the second excitation inductor L_m2And the second high-frequency transformer T₂The primary side windings are connected in parallel;

the first excitation inductance L_m1Equal to the second excitation inductance L_m2；

The first rectifying diode D₁And the second rectifying diode D₂Is connected in series with the negative pole of the third rectifying diode D₃And the fourth rectifying diode D₄Is connected in series, the first rectifying diode D₁Is connected to the third rectifier diode D₃The negative electrode of (2), the second rectifier diode D₂Is connected with the fourth rectifying diode D₄The positive electrode of (1); the first rectifying diode D₁Negative pole and the third rectifier diode D₃The common end of the negative electrode is connected with the first filter capacitor C_O1The second rectifying diode D₂An anode and the fourth rectifying diode D₄The common end of the anode is connected with the filter capacitor C_O2The negative electrode of (1); the first filter capacitor C_O1Negative pole and the second filter capacitor C_O2The positive electrodes are connected in series; the equivalent resistive load R₀And a first filter capacitor C_O1A second filter capacitor C_O2The series branch circuit formed by the filter capacitors is connected in parallel;

the first high-frequency transformer T₁A positive electrode on the primary side and the second high-frequency transformer T₂A primary side positive electrode connection; the first high-frequency transformer T₁The secondary side anode is connected with the first rectifier diode D₁And said second rectifying diode D₂The first high-frequency transformer T₁Secondary side cathode and the second high-frequency transformer T₂Secondary side positive electrodes connected in series, wherein the second high frequency transformer T₂The cathode of the secondary side is connected with the third rectifier diode D₃A fourth rectifying diode D₄A common terminal of (a);

the first high-frequency transformer T₁And the second high-frequency transformer T₂The coil turns ratios of (a) and (b) are equal;

the auxiliary fifth switch tube S₅Is connected to the third rectifying diode D₃Positive electrode and the fourth rectificationDiode D₄A common terminal of the negative electrode, the auxiliary fifth switching tube S₅Is connected with the first filter capacitor C_O1Negative pole, the second filter capacitor C_O2A common terminal of the positive electrode;

the control method comprises the following specific steps:

the pulse signal generating unit (VI) respectively outputs a pulse signal to the first switch tube S₁A second switch tube S₂A third switch tube S₃And a fourth switching tube S₄The gate outputs a pulse signal with complementary duty ratio, and the inversion network (II) inverts the direct current input voltage into square wave voltage; wherein, the first switch tube S₁A second switch tube S₂The working time of the third switch tube S is fixed to be half of a conduction period₃The working time length in one period, namely the duty ratio D, can be changed within the range of 0-D_max(ii) a The method comprises the following specific steps:

the method comprises the following steps: the pulse signal generating unit (VI) supplies a first switch tube S₁And a fourth switching tube S₄A gate pole applying a high-level pulse signal, a first switching tube S₁And a fourth switching tube S₄The upper half part of the input voltage V of the resonant network (III) forms a full-bridge inverter circuit_ab＝U_inA second input capacitor C_in2And a fourth switching tube S₄The lower half part of the resonant network (III) forms an input voltage V of a half-bridge inverter circuit_cb＝U_in2; at this time, the pulse signal generating unit (VI) is applied to the auxiliary fifth switching tube S₅The pulse signal of the gate pole is low level, the rectifier circuit (V) works in a mixed state of a full-bridge rectification mode and a voltage-multiplying rectification mode, and the alternating current transmitted by the secondary side of the transformer is converted into direct current;

step two: the pulse signal generating unit (VI) supplies a second switch tube S₂And a fourth switching tube S₄The gate pole applies high-level pulse signal, the upper half input voltage V of resonant network (III)_ab0, second input capacitance C_in2And a fourth switching tube S₄The lower half part of the resonant network (III) forms an input voltage V of a half-bridge inverter circuit_cb＝U_in2; at this time, the pulseThe impulse signal generating unit (VI) is applied to the auxiliary fifth switch tube S₅The pulse signal of the gate pole is still low level, the rectifier circuit (V) works in a full-bridge rectification mode, and the alternating current transmitted by the secondary side of the transformer is converted into direct current;

step three: the pulse signal generating unit (VI) supplies a second switch tube S₂A third switch tube S₃A gate pole applying a high-level pulse signal, a second switching tube S₂A third switch tube S₃The upper half part of the input voltage V of the resonant network (III) forms a full-bridge inverter circuit_ab＝-U_inA first input capacitor C_in1A second switch tube S₂The lower half part of the resonant network (III) forms an input voltage V of a half-bridge inverter circuit_cb＝-U_in2; at this time, the pulse signal generating unit (VI) is applied to the auxiliary fifth switching tube S₅The pulse signal of the gate pole is high level, the rectifier circuit (V) works in a voltage-multiplying rectification mode, and the alternating current transmitted by the secondary side of the transformer is converted into direct current;

under the control method, in the primary side control, the third switching tube S is changed₃The working time length in one period, namely the duty ratio D, enables the first switch tube S₁A second switch tube S₂Series branch and third switch tube S₃And a fourth switching tube S₄The full-bridge inverter circuit formed by connecting the series branches in parallel is gradually changed into a full-bridge inverter circuit from a half-bridge inverter circuit, and the third switching tube S₃And a fourth switching tube S₄Series branch and first input capacitor C_in1A second input capacitor C_in2The auxiliary half-bridge inverter circuit formed by the series branch is gradually changed from being not connected into a complete half-bridge inverter circuit, wherein D is more than or equal to 0 and less than or equal to D_max(ii) a Auxiliary fifth switch tube S₅The control of (V) realizes the self-adaptive rectification of the rectification network (V), and further realizes the wide output voltage regulation range.

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