High-power strong reset phase-shifted full-bridge zero-voltage zero-current soft-switching DC converter

Abstract

The invention discloses a high-power strong reset phase-shifted full-bridge zero-voltage zero-current soft-switching DC converter, comprising a high-voltage DC input filter unit, a converter primary-side inverter unit, a converter primary-side main circuit unit, a high-frequency transformer, and a converter secondary-side rectifier filter unit; the specific connection method is: after the input high-voltage DC is filtered in the high-voltage DC input filter unit, it passes through the power tube in the converter primary-side inverter unit to obtain an AC square wave, then passes through the converter primary-side main circuit unit to achieve soft switching, and then passes through the high-frequency transformer, and finally connects to the converter secondary-side rectifier filter unit to output a DC voltage. The problems existing in the prior art are solved, and the problem of the narrow load range of the lagging bridge arm soft switch is overcome. The voltage stress of the secondary-side rectifier device is low. Under heavy load conditions, the primary-side current can be completely reset, the duty cycle loss is small, and the reset energy is used to supply power to the auxiliary power supply to achieve lossless absorption.

Description

Technical Field

[0001] The invention belongs to the technical field of high-frequency soft-switching DC-DC converters, and in particular relates to a high-power strong-reset phase-shifted full-bridge zero-voltage zero-current soft-switching DC converter. Background Art

[0002] High-power DC power supplies are widely used in energy-consuming industrial applications such as functional material preparation and electrolytic plating, power system secondary equipment, transportation, and new energy industries. With the development of semiconductor technology, the functions of switching devices are changing with each passing day, and high-power DC switching power supplies have become an effective solution in the above fields. Figure 1 It is a traditional zero voltage switching phase-shifted full-bridge DC conversion circuit. In high-power phase-shifted full-bridge soft-switching DC switching power supplies, the degree of realization of full-range soft switching of the lagging bridge arm and the duty cycle loss during operation are two important factors affecting efficiency. When the main circuit current is reset, the main circuit inductance has a freewheeling effect, causing the primary current i p The reset time is long, the soft switching load range is narrowed, and the secondary side of the transformer is shorted, resulting in loss of duty cycle; due to the voltage ringing phenomenon caused by the junction capacitance of the resonant inductor and the secondary side rectifier diode in the circuit, the voltage stress of the secondary side rectifier device is high, such as Figure 2 As shown in the figure; the traditional zero voltage switching phase-shifted full-bridge DC conversion circuit has a primary current i under heavy load conditions. p The reset time becomes longer, resulting in a large duty cycle loss. It is very important to find a high-power DC switching power supply with full-range soft switching of the hysteresis bridge arm and low duty cycle loss. Summary of the invention

[0003] The present invention provides a high-power strong reset phase-shifted full-bridge zero-voltage zero-current soft-switching DC converter, which overcomes the problem of narrow load range of lagging bridge arm soft switching, has low voltage stress of secondary side rectifier devices, and can completely reset the primary side current under heavy load conditions, with low duty cycle loss.

[0004] To achieve the above object, the high-power strong reset phase-shifted full-bridge zero-voltage zero-current soft-switching DC converter of the present invention comprises a high-voltage DC input filter unit, a converter primary-side inverter unit, a converter primary-side main circuit unit, and a high-frequency transformer k T and the secondary side rectifier filter unit of the converter; the specific connection method is: the input high-voltage DC power is filtered by the high-voltage DC input filter unit, passes through the primary side inverter unit of the converter, obtains an AC square wave, and then passes through the primary side main circuit unit of the converter to realize soft switching, and then passes through the high-frequency transformer k T , and finally connected to the rectifier and filter unit on the secondary side of the converter to output a DC voltage;

[0005] The primary side main circuit unit of the converter includes a high frequency transformer kT The primary winding of the high-frequency transformer k T The primary leakage inductance and auxiliary circuit, the auxiliary circuit and the high frequency transformer k T The primary winding and high frequency transformer k T The primary leakage inductance is connected in series, and the auxiliary circuit includes a switch tube unit, a diode unit, and an energy storage capacitor C R and auxiliary power supply; the switch tube unit consists of switch tube Q a1 And the switch tube Q a2 The diode unit is formed by diode D a3 and diode D a4 Reverse series connection; switch tube Q a1 The connection point between the source of and the primary side of the high-frequency transformer is denoted as node 5, and the switch tube Q a2 The source and diode D a4 The connection point of the positive electrode is recorded as node 8;

[0006] The switch tube unit and the diode unit are connected in parallel at nodes 5 and 8, and the energy storage capacitor C R The first end is connected to the switch tube Q a1 The drain terminal is connected to the diode D a3 Auxiliary power supply and energy storage capacitor C R in parallel.

[0007] Furthermore, the high voltage DC input filter unit includes a capacitor C in , capacitor C in Connect in parallel with the input power supply V in both ends of .

[0008] Furthermore, the primary-side inverter unit of the converter is a full-bridge inverter circuit.

[0009] Furthermore, the converter secondary side rectifying and filtering unit includes a diode D o1 、Diode D o2 、Inductance L o and capacitor C o , diode D o1 The positive pole is connected to the high frequency transformer k T The first secondary winding has the same name end, diode D o1 The negative electrode and the inductor L o The first end of the inductor L o The second end of the capacitor C o The first end of the capacitor C o The second end of the high frequency transformer k T The second secondary winding is connected to the same end, capacitor C o The two ends of the load R are connected in parallel o , diode D o2The positive pole of the high frequency transformer k T The secondary winding of the diode D is connected to the opposite end of the o2 The positive electrode and D o1 negative connection.

[0010] Furthermore, the auxiliary power supply is a DC module power supply.

[0011] Furthermore, the switch tube Q a1 And the switch tube Q a2 Choose MOS tube.

[0012] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0013] 1. Compared with the traditional zero voltage switching phase-shifted full-bridge DC converter, the auxiliary circuit of the invention can charge and discharge the junction capacitance of the switch tube in a shorter time, so that the high-power strong reset phase-shifted full-bridge zero voltage zero current soft switching DC converter has the characteristics of full-range soft switching of the lagging bridge arm;

[0014] 2. When the auxiliary circuit is turned on, the auxiliary power supply passes through capacitor C R Discharge weakens the resonance of the main circuit, reduces the voltage ringing in the secondary circuit of the transformer, and reduces the voltage stress of the secondary rectifier device, which is beneficial to the device selection in design and production;

[0015] 3. The auxiliary circuit of the invention is provided by a capacitor C R Discharging can make the main circuit current commutation speed faster. Under heavy load conditions, the primary current can be completely reset and the duty cycle loss is low. This improves the problem that the primary current of the traditional zero-voltage switching phase-shifted full-bridge DC converter cannot be reset under heavy load conditions, resulting in a large duty cycle loss. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is the schematic diagram of the traditional zero voltage switching phase-shifted full-bridge DC conversion circuit;

[0017] Figure 2 This is a problem existing in the traditional zero voltage and zero current switching phase-shifted full-bridge inverter circuit;

[0018] Figure 3 It is the overall schematic diagram of the circuit of the present invention;

[0019] Figure 4 This is a schematic diagram of an ideal working waveform of the circuit of the present invention;

[0020] Figure 5 Yes 0 The previous working state diagram is called working mode 1;

[0021] Figure 6 Yes0 ~t 2 The working state diagram is called working mode 2;

[0022] Figure 7 Yes 2 ~t 3 The working state diagram is called working mode 3;

[0023] Figure 8 Yes 3 ~t 4 The working state diagram is called working mode 4;

[0024] Fig. 9 Yes 4 ~t 5 The working state diagram is called working mode 5;

[0025] Fig.10 Yes 5 ~t 7 The working state diagram is called working mode 6;

[0026] Fig.11 Yes 7 ~t 9 The working state diagram is called working mode 7;

[0027] Fig.12 Yes 9 ~t 10 The working state diagram is called working mode 8;

[0028] Fig.13 Yes 10 ~t 11 The working state diagram is called working mode 9;

[0029] Fig.14 Yes 11 ~t 12 The working state diagram is called working mode 10;

[0030] Figure 3 as well as Figures 5 to 14 In the diagram, each node is represented by a number from 1 to 13. DETAILED DESCRIPTION

[0031] In order to make the purpose and technical solution of the present invention clearer and easier to understand, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. The specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0032] In the description of the present invention, it should be understood that the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, and it can be the internal connection of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0033] A novel phase-shifted full-bridge zero-voltage zero-current soft-switching high-frequency DC converter improves the deficiencies of the traditional zero-voltage switching phase-shifted full-bridge DC converter by adding two reverse-series switching tubes, two reverse-series diodes, a storage capacitor, and an auxiliary power supply to the traditional zero-voltage switching phase-shifted full-bridge DC conversion circuit topology.

[0034] Reference Figure 3 The high-power strong reset phase-shifted full-bridge zero-voltage zero-current soft-switching DC converter includes a high-voltage DC input filter unit, a converter primary-side inverter unit, a converter primary-side main circuit unit, a high-frequency transformer, and a converter secondary-side rectifier filter unit. The model of the power tube is selected according to the voltage level. The specific connection method is as follows: after the input high-voltage DC power is filtered in the high-voltage DC input filter unit, it passes through the power tube in the converter primary-side inverter unit to obtain an AC square wave, and then passes through the converter primary-side main circuit unit to realize soft switching, and then passes through the high-frequency transformer, and finally connects to the converter secondary-side rectifier filter unit to output a DC voltage.

[0035] Among them, the high-voltage DC input filter unit includes a capacitor C in , capacitor C in Connect in parallel with the input power supply V in The inverter unit on the primary side of the converter is a full-bridge inverter circuit, including a switch tube Q 1 , switch tube Q 2 , switch tube Q 3 And the switch tube Q 4 Among them, the switch tube Q 1 And the switch tube Q 2 In the same bridge arm, the switch tube Q 3 And the switch tube Q 4 On the same bridge arm.

[0036] The primary side main circuit unit of the converter includes a series-connected primary winding of the transformer, a primary leakage inductance of the transformer and an auxiliary circuit. The auxiliary circuit has a switch tube unit, a diode unit, and an energy storage capacitor C RAnd an auxiliary power supply. Among them, the switch tube unit consists of a switch tube Q a1 And the switch tube Q a2 Reverse series connection, switch tube Q a1 The connection point between the source of and the primary side of the transformer is denoted as node 5, and the switch tube Q a2 The source and diode D a4 The connection point of the positive electrode is denoted as node 8. The diode unit consists of a diode D a3 and diode D a4 The auxiliary power supply adopts the common DC module power supply on the market, and its model is selected according to the actual needs of the application scenario.

[0037] The switch tube unit and the diode unit are connected in parallel between nodes 5 and 8, and the energy storage capacitor and the auxiliary power supply are connected between nodes 6 and 7. By controlling the switch tube, the auxiliary power supply charges and discharges the energy storage capacitor to realize the soft switching of the converter. a1 The drain and switch Q a1 The connection point of the drain of the diode D a3 The cathode of diode D a4 The negative connection point.

[0038] The secondary side rectifier and filter unit of the converter includes a diode D o1 、Diode D o2 、Inductance L o and capacitor C o , diode D o1 The positive pole is connected to the high frequency transformer k T The first secondary winding has the same name end, D o1 The negative electrode and the inductor L o The first end of the inductor L o The second end of the capacitor C o The first end of the capacitor C o The second end and k T The second secondary winding is connected to the same end, capacitor C o The two ends of the load R are connected in parallel o , diode D o2 The positive pole of the high frequency transformer k T The secondary winding of the diode D is connected to the opposite end of the o2 The positive electrode and D o1 negative connection.

[0039] Figure 4 It is a schematic diagram of an ideal working waveform of the circuit of the present invention.

[0040] Figure 5 Yes 0 The working state diagram before is called working mode 1; during this period, the primary switch tube Q1 , switch tube Q 4 , switch tube Q a1 , switch tube Q a2 and secondary diode D o1 At the same time, the primary current flows from the voltage V in Starting from the positive electrode, through the capacitor C in Filter, flow through the switch tube Q in turn 1 、Inductance L lk , the primary side of the high-frequency transformer, the switch tube Q a1 , switch tube Q a2 And the switch tube Q 4 Back to the voltage source V in Negative pole; the secondary current of the high-frequency transformer flows from the secondary side through the diode D in sequence o1 , LC filtering and load R o , and finally flows back to the secondary side of the high-frequency transformer from the same-name end of the transformer; the switch tube Q 2 And the switch tube Q 3 No current flows when the switch is turned off, D a4 Reverse cutoff, no current flows; the auxiliary power supply is capacitor C R Charge until the capacitor C R Fully charged, capacitor C R The voltage is equal to the auxiliary power supply voltage.

[0041] Figure 6 Yes 0 ~t 2 The working state diagram is called working mode 2; t 0 When the switch tube Q is turned off 1 , the primary switch tube Q of the converter 4 , switch tube Q a1 , switch tube Q a2 and secondary diode D o1 , D o2 At the same time, the primary current i p Flows through the switch tube Q in sequence 4 , switch tube Q 2 The body diode D 2 , the primary side of the high-frequency transformer, the inductor L lk , switch tube Q a1 And the switch tube Q a2 , in the inductor L lk Under the action of continuous flow; part of the secondary current of the high-frequency transformer flows through the diode D o1 , the other part flows through diode D o2 , then flows through the LC filter and the load in turn, and finally flows back to the secondary side of the high-frequency transformer from the same-name end of the transformer. The secondary side of the transformer is in a short-circuited state; the voltage between the primary and secondary sides of the high-frequency transformer gradually decreases until t 1The time is zero, at which time the primary and secondary sides of the high-frequency transformer are short-circuited; the switch tube Q 2 And the switch tube Q 3 No current flows through the diode D. a4 Reverse cutoff, no current flows; switch tube Q 2 The voltage at both ends is 0, which can achieve zero voltage conduction; the auxiliary power supply is capacitor C R After fully charged, the auxiliary power supply makes the capacitor C R The voltage is kept equal to the auxiliary power supply voltage.

[0042] Figure 7 Yes 2 ~t 3 The working state diagram is called working mode 3; t 2 Always turn off the switch tube Q a1 , turn on the switch tube Q 2 , the primary switch tube Q of the converter 4 , switch tube Q a2 and diode D a3 And the secondary diode D o1 and diode D o2 At the same time, the primary current i p Flows through the switch tube Q in sequence 4 , switch tube Q 2 , the primary side of the high-frequency transformer, the inductor L lk 、Diode D a3 , capacitor C R And the switch tube Q a2 , since the auxiliary power supply is connected through capacitor C R Reverse discharge releases energy and suppresses the primary current i p , the primary current and the secondary current decrease until t 3 The secondary current of the high-frequency transformer flows from the diode D o1 outflow, part of which flows from diode D o2 It flows out, passes through the LC filter and the load in turn, and finally flows back to the secondary side of the high-frequency transformer from the same-name end of the transformer. The secondary side of the transformer is in a short-circuited state. Figure 8 Yes 3 ~t 4 The working state diagram is called working mode 4; at this time, the primary and secondary voltages of the high-frequency transformer are both zero, and the primary current is t 3 Drops to zero; the secondary diode D o1 and diode D o2 At the same time, the load current is evenly divided. The two parts of the current then flow through the LC filter and the load in turn, and finally flow back to the secondary side of the high-frequency transformer from the same-name end of the transformer. The secondary side of the transformer is in a short-circuited state; the primary switch tube Q 2 , switch tube Q 4 And the switch tube Qa2 At the same time, the auxiliary power supply is capacitor C R Charge until the capacitor C R Fully charged, capacitor C R The voltage is equal to the auxiliary power supply voltage.

[0043] Fig. 9 Yes 4 ~t 5 The working state diagram is called working mode 5; t 4 Zero current turns off the switch tube Q 4 At this time, the primary and secondary currents of the high-frequency transformer are both zero, and the voltage is both zero, which is the same as working mode 4; the auxiliary power supply ensures that the capacitor C R The voltage remains unchanged, and the auxiliary power supply voltage and capacitor C R The voltages are equal.

[0044] Fig.10 Yes 5 ~t 7 The working state diagram is called working mode 6; during this period, the primary switch tube Q 2 , switch tube Q 3 , switch tube Q a1 , switch tube Q a2 and secondary diode D o2 At the same time, the primary current reverses and rises from 0 to the rated value, from the voltage V in Starting from the positive electrode, through the capacitor C in Filter, flow through the switch tube Q in turn 3 , switch tube Q a1 , switch tube Q a2 、Inductance L lk , the primary side of the high-frequency transformer and the switch tube Q 2 , back to the negative pole of the voltage source; the secondary current of the high-frequency transformer flows through the diode D in turn o2 , LC filtering and load, and finally flows back to the secondary side of the high-frequency transformer from the same-name end of the transformer; the switch tube Q 1 And the switch tube Q 4 No current flows when the switch is turned off, D a4 Reverse cutoff, no current flows; auxiliary power supply ensures capacitor C R The voltage remains unchanged, and the auxiliary power supply voltage and capacitor C R The voltages are equal.

[0045] Fig.11 Yes 7 ~t 9 The working state diagram is called working mode 7; t 7 When zero voltage turns off the switch tube Q 2 , the primary switch tube Q of the converter 3, switch tube Q a1 , switch tube Q a2 and secondary diode D o1 , D o2 At the same time, the primary current i p Flows through the switch tube Q in sequence 1 The body diode D 1 , switch tube Q 3 , switch tube Q a1 , switch tube Q a2 、Inductance L lk and the primary side of the high-frequency transformer, in the inductor L lk The secondary current of the high-frequency transformer flows from the diode D o1 outflow, part of which flows from diode D o2 It flows out, flows through the LC filter and the load in turn, and finally flows back to the secondary side of the high-frequency transformer from the same-name end of the transformer. The secondary side of the transformer is in a short-circuited state; the voltage between the primary and secondary sides of the high-frequency transformer gradually decreases until t 8 The time is zero; the switch tube Q 1 And the switch tube Q 4 No current flows when the switch is turned off, D a4 Reverse cutoff, no current flows; auxiliary power supply ensures capacitor C R The voltage remains unchanged, and the auxiliary power supply voltage and capacitor C R The voltages are equal.

[0046] Fig.12 Yes 9 ~t 10 The working state diagram is called working mode 8; t 9 Always turn off the switch tube Q a2 , turn on the switch tube Q 1 , switch tube Q 3 , switch tube Q a1 and diode D a4 And the secondary diode D o1 and diode D o2 At the same time, the primary current i p Flows through the switch tube Q in sequence 1 , switch tube Q 3 、Diode D a4 , capacitor C R , switch tube Q a1 、Inductance L lk and the primary side of the high-frequency transformer. Since the auxiliary power supply is connected to the capacitor C R Reverse discharge releases energy and suppresses the primary current i p , the primary current and the secondary current decrease until t 10 The secondary current of the high-frequency transformer flows from the diode D o1outflow, part of which flows from diode D o2 It flows out, passes through the LC filter and the load in turn, and finally flows back to the secondary side of the high-frequency transformer from the same-name end of the transformer. The secondary side of the transformer is in a short-circuited state.

[0047] Fig.13 Yes 10 ~t 11 The working state diagram is called working mode 9; at this time, the primary and secondary voltages of the high-frequency transformer are both zero, and the primary current is t 10 Drops to zero; the secondary diode D o1 and diode D o2 At the same time, the load current is evenly divided. The two parts of the current then flow through the LC filter and the load in turn, and finally flow back to the secondary side of the high-frequency transformer from the same-name end of the transformer. The secondary side of the transformer is in a short-circuited state; the primary switch tube Q 1 , switch tube Q 3 , switch tube Q a1 At the same time, the auxiliary power supply is capacitor C R Charge until the capacitor C R Fully charged, capacitor C R The voltage is equal to the auxiliary power supply voltage.

[0048] Fig.14 Yes 11 ~t 12 The working state diagram is called working mode 10; t 11 Always turn off the switch tube Q 3 At this time, the primary and secondary currents of the high-frequency transformer are both zero, and the voltages are both zero, which is the same as working mode 9; the auxiliary power supply ensures that the capacitor C R The voltage remains unchanged, and the auxiliary power supply voltage and capacitor C R The voltages are equal.

[0049] So far, one cycle of the circuit operation of the present invention has been described. Compared with the traditional zero voltage zero current switching phase-shifted full-bridge circuit, the present invention overcomes the problem of narrow load range of the lagging bridge arm soft switch, the voltage stress of the secondary rectifier device is low, and under heavy load conditions, the primary current can be completely reset, the duty cycle loss is small, and the reset energy is used to supply power to the auxiliary power supply, realizing lossless absorption.

[0050] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. High-power strong reset phase-shifted full-bridge zero-voltage zero-current soft-switching DC converter, characterized in that: It includes high-voltage DC input filter unit, converter primary side inverter unit, converter primary side main circuit unit, high-frequency transformer k T The specific connection method is as follows: after the input high-voltage DC power is filtered by the high-voltage DC input filter unit, it passes through the primary-side inverter unit of the converter to obtain an AC square wave, and then passes through the primary-side main circuit unit of the converter to realize soft switching, and then passes through the high-frequency transformer k T , and finally connected to the rectifier and filter unit on the secondary side of the converter to output a DC voltage; The primary side main circuit unit of the converter includes a high frequency transformer k T The primary winding and high frequency transformer k T The primary leakage inductance and auxiliary circuit of the auxiliary circuit and the high frequency transformer k T The primary winding and high frequency transformer k T The primary leakage inductance is connected in series, and the auxiliary circuit includes a switch tube unit, a diode unit, and an energy storage capacitor C R and auxiliary power supply; the switch tube unit is composed of a switch tube Q a1 And the switch tube Q a2 The diode unit is formed by diode D a3 and diode D a4 Reverse series connection; switch tube Q a1 The connection point between the source of and the primary side of the high-frequency transformer is denoted as node 5, and the switch tube Q a2 The source and diode D a4 The connection point of the positive electrode is recorded as node 8; The switch tube unit and the diode unit are connected in parallel at nodes 5 and 8, and the energy storage capacitor C R The first end is connected to the switch tube Q a1 The drain terminal is connected to the diode D a3 Auxiliary power supply and energy storage capacitor C R in parallel; The high voltage DC input filter unit includes a capacitor C in , the capacitor C in Connect in parallel with the input power supply V in both ends of .

2. The high-power strong reset phase-shifted full-bridge zero-voltage zero-current soft-switching DC converter according to claim 1 is characterized in that: The inverter unit on the primary side of the converter is a full-bridge inverter circuit.

3. The high-power strong reset phase-shifted full-bridge zero-voltage zero-current soft-switching DC converter according to claim 1 is characterized in that: The converter secondary side rectifying and filtering unit comprises a diode D o1 、Diode D o2 、Inductance L o and capacitor C o , the diode D o1 The positive pole is connected to the high frequency transformer k T The first secondary winding has the same name end, diode D o1 The negative electrode and the inductor L o The first end of the inductor L o The second end of the capacitor C o The first end of the capacitor C o The second end of the high frequency transformer k T The second secondary winding is connected to the same end, capacitor C o The two ends of the load R are connected in parallel o , diode D o2 The positive pole of the high frequency transformer k T The secondary winding of the diode D is connected to the opposite end of the o2 The positive electrode and D o1 negative connection.

4. The high-power strong reset phase-shifted full-bridge zero-voltage zero-current soft-switching DC converter according to claim 1 is characterized in that: The auxiliary power supply is a DC module power supply.

5. The high-power strong reset phase-shifted full-bridge zero-voltage zero-current soft-switching DC converter according to claim 1 is characterized in that: The switch tube Q a1 And the switch tube Q a2 Choose MOS tube.

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