A wide range soft switching full-bridge inverter circuit and device based on controllable inductance

Abstract

The present invention provides a wide-range soft-switching full-bridge inverter circuit and device based on controllable inductance. By changing the inductance values ​​of a first variable inductance unit and a second variable inductance unit during the process of inverting the DC power supply module by a phase-shifted full-bridge converter and a cycloconverter, the circuit achieves wide-range soft-switching operation of the phase-shifted full-bridge converter, thereby reducing switching losses of the inverter during operation and improving system conversion efficiency.

Description

Technical Field

[0001] The present invention relates to the field of high-frequency inverter power supplies, and in particular to a wide-range soft-switching full-bridge inverter circuit and device based on controllable inductance. Background Art

[0002] The leading arm and lagging arm in the high-frequency link inverter alternate once every half power frequency cycle. The leading arm relies on the sum of the energy in the leakage inductance and the filter inductance to achieve zero voltage turn-on; while the lagging arm can only rely on the energy stored in the leakage inductance of the transformer, which makes it more difficult to achieve zero voltage turn-on; and the current in the filter inductor during the inverter process is an alternating sinusoidal quantity, so when the filter inductor current is very small or zero, it is also difficult to achieve zero voltage turn-on of the leading arm.

[0003] Currently, the scope of soft switching of the phase-shifted full-bridge switch tube in the high-frequency link inverter is limited. The existing technology has not proposed a solution to achieve soft switching from the perspective of controlling the size of the resonant inductor, and it is impossible to achieve soft switching of the phase-shifted full-bridge switch tube in the high-frequency link inverter throughout the entire inverter process. Under high-frequency working conditions, switching losses will still increase, reducing the efficiency of the converter.

[0004] In view of this, this application is filed. Summary of the Invention

[0005] The present invention discloses a wide-range soft-switching full-bridge inverter circuit and device based on controllable inductance, aiming to reduce switching losses during inverter operation and improve system conversion efficiency. A first embodiment of the present invention provides a wide-range soft-switching full-bridge inverter circuit based on controllable inductance, comprising: a DC power supply module, a circulating current suppression circuit, a first variable inductance unit, a second variable inductance unit, a phase-shifted full-bridge converter, a first transformer, a cycloconverter, and a filter;

[0006] The circulating current suppression circuit is connected to both ends of the DC power supply module, the output end of the DC power supply module is electrically connected to the input end of the phase-shifted full-bridge converter, the output end of the phase-shifted full-bridge converter is electrically connected to the primary winding of the first transformer, the secondary winding of the first transformer is electrically connected to the input end of the cycloconverter, the output end of the cycloconverter is connected to the input end of the filter, and the output end of the filter is connected to the load.

[0007] A first end of the first variable inductor unit is electrically connected to a midpoint of the circulating current suppression circuit, a second end of the first variable inductor unit is electrically connected to a midpoint of one bridge arm of the phase-shifted full-bridge converter, a first end of the second variable inductor unit is electrically connected to the midpoint of the circulating current suppression circuit, and a second end of the second variable inductor unit is electrically connected to a midpoint of the other bridge arm of the phase-shifted full-bridge converter;

[0008] The first variable inductor unit and the second variable inductor unit are configured to adjust their own inductance according to the switching signal;

[0009] The phase-shifted full-bridge converter is configured to achieve soft switching during a sinusoidal wave inversion process according to the varying inductance value of the first variable inductor unit and the varying inductance value of the second variable inductor unit.

[0010] Preferably, the first variable inductor unit includes: a second transformer, a first excitation inductor, a first leakage inductor, and a first bidirectional switch tube;

[0011] The middle part of the circulating current suppression circuit is connected to the first end of the primary winding of the second transformer through the first leakage inductor, the second end of the primary winding of the second transformer is electrically connected to the midpoint of one of the bridge arms of the phase-shifted full-bridge converter, the first excitation inductor is connected to both ends of the primary winding of the second transformer, and the first bidirectional switch tube is connected to both ends of the secondary winding of the second transformer.

[0012] Preferably, the second variable inductor unit includes: a third transformer, a second excitation inductor, a second leakage inductor, and a second bidirectional switch tube;

[0013] The middle part of the circulating current suppression circuit is connected to the first end of the primary winding of the third transformer through the second leakage inductance, the second end of the primary winding of the third transformer is electrically connected to the midpoint of the other bridge arm of the phase-shifted full-bridge converter, the second excitation inductor is connected to both ends of the primary winding of the third transformer, and the second bidirectional switch tube is connected to both ends of the secondary winding of the third transformer.

[0014] Preferably, the phase-shifted full-bridge converter includes a first MOS transistor, a second MOS transistor, a third MOS transistor, a fourth MOS transistor, a first capacitor, a second capacitor, a third capacitor, and a fourth capacitor;

[0015] The D pole of the first MOS transistor is electrically connected to the D pole of the second MOS transistor, the S pole of the first MOS transistor is electrically connected to the D pole of the third MOS transistor, the S pole of the second MOS transistor is electrically connected to the D pole of the fourth MOS transistor, the S pole of the third MOS transistor is electrically connected to the S pole of the fourth MOS transistor, the first capacitor is electrically connected to the S pole and D pole of the first MOS transistor, the second capacitor is electrically connected to the S pole and D pole of the second MOS transistor, the third capacitor is electrically connected to the S pole and D pole of the third MOS transistor, and the fourth capacitor is electrically connected to the S pole and D pole of the fourth MOS transistor;

[0016] The S pole of the first MOS transistor is electrically connected to the second end of the primary winding of the second transformer, the S pole of the first MOS transistor is electrically connected to the first end of the primary winding of the first transformer, the S pole of the second MOS transistor is electrically connected to the second end of the primary winding of the third transformer, and the S pole of the second MOS transistor is electrically connected to the second end of the primary winding of the first transformer.

[0017] Preferably, the cycloconverter includes a first diode, a second diode, a third diode, a fourth diode, a fifth diode, a sixth diode, a seventh diode, an eighth diode, a fifth MOS transistor, and a sixth MOS transistor;

[0018] The cathode of the first diode is electrically connected to the cathode of the second diode and the D electrode of the fifth MOS transistor, the anode of the third diode is electrically connected to the anode of the fourth diode and the S electrode of the fifth MOS transistor, the anode of the first diode is electrically connected to the cathode of the third diode, and the anode of the second diode is electrically connected to the cathode of the fourth diode;

[0019] The cathode of the fifth diode is electrically connected to the cathode of the sixth diode and the D electrode of the sixth MOS transistor, the anode of the seventh diode is electrically connected to the anode of the eighth diode and the S electrode of the sixth MOS transistor, the anode of the fifth diode is electrically connected to the cathode of the seventh diode, and the anode of the sixth diode is electrically connected to the cathode of the eighth diode;

[0020] The anode of the first diode is electrically connected to the first end of the secondary winding of the first transformer, and the anode of the fifth diode is electrically connected to the second end of the secondary winding of the first transformer.

[0021] Preferably, the filter includes a filter inductor and a filter capacitor;

[0022] The first end of the filter inductor is electrically connected to the cathode of the fourth diode, the second end of the filter inductor is electrically connected to the first end of the filter capacitor, and the second end of the filter capacitor is electrically connected to the middle portion of the secondary winding of the first transformer.

[0023] Preferably, the first bidirectional switch tube includes a ninth diode, a tenth diode, an eleventh diode, a twelfth diode, and a seventh MOS tube;

[0024] The cathode of the ninth diode is electrically connected to the cathode of the tenth diode and the D electrode of the seventh MOS transistor, the anode of the eleventh diode is electrically connected to the anode of the twelfth diode and the S electrode of the seventh MOS transistor, the anode of the ninth diode is electrically connected to the cathode of the eleventh diode, and the anode of the tenth diode is electrically connected to the cathode of the twelfth diode;

[0025] The anodes of the nine diodes are electrically connected to the first end of the secondary winding of the second transformer, and the cathode of the twelfth diode is electrically connected to the second end of the secondary winding of the second transformer.

[0026] Preferably, the second bidirectional switch tube includes a thirteenth diode, a fourteenth diode, a fifteenth diode, a sixteenth diode, and an eighth MOS tube;

[0027] The cathode of the thirteenth diode is electrically connected to the cathode of the fourteenth transistor and the D electrode of the eighth MOS transistor, the anode of the fifteenth diode is electrically connected to the anode of the sixteenth diode and the S electrode of the eighth MOS transistor, the anode of the thirteenth diode is electrically connected to the cathode of the fifteenth diode, and the anode of the fourteenth diode is electrically connected to the cathode of the sixteenth diode;

[0028] The anode of the thirteenth diode is electrically connected to the first end of the secondary winding of the third transformer, and the cathode of the sixteenth diode is electrically connected to the second end of the secondary winding of the third transformer.

[0029] A second embodiment of the present invention provides a soft switching device for a single-phase sinusoidal wave inverter based on a controllable inductor, comprising a controller and a wide-range soft switching full-bridge inverter circuit based on a controllable inductor as described in any one of the above items, wherein the controller is electrically connected to the control end of the first variable inductor unit, the control end of the second variable inductor unit, the control end of the phase-shifted full-bridge converter, and the control end of the cycloconverter.

[0030] The present invention provides a wide-range soft-switching full-bridge inverter circuit and device based on controllable inductance. The circuit and device achieve soft switching of the phase-shifted full-bridge converter by changing the self-inductance values ​​of the first variable inductance unit and the second variable inductance unit during the process of inverting the DC power supply module by the phase-shifted full-bridge converter and the cycloconverter, thereby reducing the switching loss of the inverter during operation and improving the inverter efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of a wide-range soft-switching full-bridge inverter circuit based on controllable inductance provided by the first embodiment of the present invention;

[0032] Figure 2 It is an equivalent circuit diagram of a wide range soft switching full-bridge inverter circuit based on controllable inductance;

[0033] Figure 3-6 The present invention is a schematic diagram of the operation of the equivalent circuit of a wide-range soft-switching full-bridge inverter circuit based on controllable inductance in the positive half cycle. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention for which protection is sought, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0035] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0036] The present invention discloses a wide-range soft-switching full-bridge inverter circuit and device based on controllable inductance, aiming to reduce the switching loss of the inverter during operation while improving the inverter efficiency.

[0037] The first embodiment of the present invention provides a wide-range soft-switching full-bridge inverter circuit based on controllable inductance, comprising: a DC power supply module, a circulating current suppression circuit, a first variable inductor unit 1, a second variable inductor unit 2, a phase-shifted full-bridge converter 3, a first transformer T1, a cycloconverter 4, and a filter 5;

[0038] The circulating current suppression circuit is located at both ends of the DC power supply module. The output end of the DC power supply module is electrically connected to the input end of the phase-shifted full-bridge converter 3. The output end of the phase-shifted full-bridge converter 3 is electrically connected to the primary winding of the first transformer T1. The secondary winding of the first transformer T1 is electrically connected to the input end of the cycloconverter 4. The output end of the cycloconverter 4 is connected to the input end of the filter 5. The output end of the filter is connected to a load. The first end of the first variable inductance unit 1 is electrically connected to the midpoint of the circulating current suppression circuit. The second end of the first variable inductance unit 1 and the second end of the first variable inductance unit are electrically connected to the midpoint of one of the bridge arms of the phase-shifted full-bridge converter 3. The first end of the second variable inductance unit 2 is electrically connected to the midpoint of the circulating current suppression circuit. The second end of the second variable inductance unit 2 is electrically connected to the midpoint of the other bridge arm of the phase-shifted full-bridge converter.

[0039] The first variable inductor unit 1 and the second variable inductor unit 2 are configured to adjust their own inductance according to the switching signal;

[0040] The phase-shifted full-bridge converter 3 is configured to perform soft switching during a sinusoidal wave inversion process according to the varying inductance of the first variable inductor unit 1 and the varying inductance of the second variable inductor unit 2 .

[0041] It should be noted that the circulating current suppression circuit is composed of two capacitors, namely C5 and C6, and two diodes, namely VD1 and VD2, which can effectively suppress the circulating current.

[0042] In a possible embodiment of the present invention, the first variable inductor unit 1 includes: a second transformer T2, a first excitation inductor L1, a first leakage inductor Lk1, and a first bidirectional switch tube;

[0043] The middle part of the circulating current suppression circuit is connected to the first end of the primary winding of the second transformer T2 through the first leakage inductor Lk1, the second end of the primary winding of the second transformer T2 is electrically connected to the midpoint of one of the bridge arms of the phase-shifted full-bridge converter 3, the first excitation inductor L1 is connected to both ends of the primary winding of the second transformer T2, and the first bidirectional switch tube is connected to both ends of the secondary winding of the second transformer T2.

[0044] Preferably, the first bidirectional switch includes a ninth diode D9, a tenth diode D10, an eleventh diode D11, a twelfth diode D12, and a seventh MOS transistor Q7;

[0045] The cathode of the ninth diode D9 is electrically connected to the cathode of the tenth diode D10 and the D electrode of the seventh MOS transistor Q7. The anode of the eleventh diode D11 is electrically connected to the anode of the twelfth diode D12 and the S electrode of the seventh MOS transistor Q7. The anode of the ninth diode D9 is electrically connected to the cathode of the eleventh diode D11. The anode of the tenth diode D10 is electrically connected to the cathode of the twelfth diode D12.

[0046] An anode of the ninth diode D9 is electrically connected to a first end of the secondary winding of the second transformer T2 , and a cathode of the twelfth diode D12 is electrically connected to a second end of the secondary winding of the second transformer T2 .

[0047] It should be noted that L1 is the magnetizing inductance, and Lin is the equivalent input inductance. A first bidirectional switch is connected to the secondary side of the second transformer T2, which can be composed of a seventh MOS transistor Q7 and diodes D9 / D10 / D11 / D12. When the seventh MOS transistor Q7 is off, the secondary side of the second transformer T2 is open-circuited, and Lin = LK1 + L1. When the switch S is on, the secondary side of the second transformer T2 is short-circuited, and Lin = LK1. Assuming the period of the switch S is TS, the on-time within one period is DTS, and D is the duty cycle, a controllable variable inductance Lin = LK1 + (1-D) L1 is obtained within one switching period.

[0048] In a possible embodiment of the present invention, the second variable inductor unit 2 includes: a third transformer T3, a second excitation inductor L2, a second leakage inductor Lk2, and a second bidirectional switch tube;

[0049] The middle part of the circulating current suppression circuit is connected to the first end of the primary winding of the third transformer T3 through the second leakage inductor Lk2, the second end of the primary winding of the third transformer T3 is electrically connected to the midpoint of the other bridge arm of the phase-shifted full-bridge converter 3, the second excitation inductor L2 is connected to both ends of the primary winding of the third transformer T3, and the second bidirectional switch tube is connected to both ends of the secondary winding of the third transformer T3.

[0050] Preferably, the second bidirectional switch includes a thirteenth diode D13, a fourteenth diode D14, a fifteenth diode D15, a sixteenth diode D16, and an eighth MOS transistor Q8;

[0051] The cathode of the thirteenth diode D13 is electrically connected to the cathode of the fourteenth diode and the D electrode of the eighth MOS transistor Q8, the anode of the fifteenth diode D15 is electrically connected to the anode of the sixteenth diode D16 and the S electrode of the eighth MOS transistor Q8, the anode of the thirteenth diode D13 is electrically connected to the cathode of the fifteenth diode D15, and the anode of the fourteenth diode D14 is electrically connected to the cathode of the sixteenth diode D16;

[0052] An anode of the thirteenth diode D13 is electrically connected to a first end of the secondary winding of the third transformer T3 , and a cathode of the sixteenth diode D16 is electrically connected to a second end of the secondary winding of the third transformer T3 .

[0053] It should be noted that L2 is the magnetizing inductance, and Lin is the equivalent input inductance. A first bidirectional switch is connected to the secondary side of the third transformer T3, which can be composed of an eighth MOS transistor Q8 and diodes D13 / D14 / D15 / D16. When the eighth MOS transistor Q8 is off, the secondary side of the third transformer T3 is open-circuited, and Lin = LK2 + L2; when the eighth MOS transistor Q8 is on, the secondary side of the third transformer T3 is short-circuited, and Lin = LK2. Assuming the period of the eighth MOS transistor Q8 is TS, the on-time within one period is DTS, and D is the duty cycle, a controllable variable inductance Lin = LK2 + (1-D) L2 is obtained within one switching period.

[0054] In a possible embodiment of the present invention, the phase-shifted full-bridge converter 3 includes a first MOS transistor Q1, a second MOS transistor Q2, a third MOS transistor Q3, a fourth MOS transistor Q4, a first capacitor C1, a second capacitor C2, a third capacitor C3, and a fourth capacitor C4;

[0055] The D pole of the first MOS transistor Q1 is electrically connected to the D pole of the second MOS transistor Q2, the S pole of the first MOS transistor Q1 is electrically connected to the D pole of the third MOS transistor Q3, the S pole of the second MOS transistor Q2 is electrically connected to the D pole of the fourth MOS transistor Q4, the S pole of the third MOS transistor Q3 is electrically connected to the S pole of the fourth MOS transistor Q4, the first capacitor C1 is electrically connected to the S pole and D pole of the first MOS transistor Q1, the second capacitor C2 is electrically connected to the S pole and D pole of the second MOS transistor Q2, the third capacitor C3 is electrically connected to the S pole and D pole of the third MOS transistor Q3, and the fourth capacitor C4 is electrically connected to the S pole and D pole of the fourth MOS transistor Q4;

[0056] The S pole of the first MOS transistor Q1 is electrically connected to the second end of the primary winding of the second transformer T2, the S pole of the first MOS transistor Q1 is electrically connected to the first end of the primary winding of the first transformer T1, the S pole of the second MOS transistor Q2 is electrically connected to the second end of the primary winding of the third transformer T3, and the S pole of the second MOS transistor Q2 is electrically connected to the second end of the primary winding of the first transformer T1.

[0057] It should be noted that the first MOS transistor Q1, the second MOS transistor Q2, the third MOS transistor Q3, and the fourth MOS transistor Q4 constitute the main bridge arm switch of the phase-shifted full-bridge converter 3, and the first capacitor C1, the second capacitor C2, the third capacitor C3, and the fourth capacitor C4 are parasitic capacitors of the phase-shifted full-bridge main bridge arm switch.

[0058] In a possible embodiment of the present invention, the cycloconverter 4 includes a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5, a sixth diode D6, a seventh diode D7, an eighth diode D8, a fifth MOS transistor Q5, and a sixth MOS transistor Q6;

[0059] The cathode of the first diode D1 is electrically connected to the cathode of the second diode D2 and the D electrode of the fifth MOS transistor Q5, the anode of the third diode D3 is electrically connected to the anode of the fourth diode D4 and the S electrode of the fifth MOS transistor Q5, the anode of the first diode D1 is electrically connected to the cathode of the third diode D3, and the anode of the second diode D2 is electrically connected to the cathode of the fourth diode D4;

[0060] The cathode of the fifth diode D5 is electrically connected to the cathode of the sixth diode D6 and the D electrode of the sixth MOS transistor Q6. The anode of the seventh diode D7 is electrically connected to the anode of the eighth diode D8 and the S electrode of the sixth MOS transistor Q6. The anode of the fifth diode D5 is electrically connected to the cathode of the seventh diode D7. The anode of the sixth diode D6 is electrically connected to the cathode of the eighth diode D8.

[0061] An anode of the first diode D1 is electrically connected to a first end of the secondary winding of the first transformer T1 , and an anode of the fifth diode D5 is electrically connected to a second end of the secondary winding of the first transformer T1 .

[0062] It should be noted that the fifth MOS transistor Q5 and the sixth MOS transistor Q6 are bidirectional switches of the cycloconverter 4, and the first diode D1, the second diode D2, the third diode D3, the fourth diode D4, the fifth diode D5, the sixth diode D6, the seventh diode D7, and the eighth diode D8 are used to provide a loop for the bidirectional switch of the cycloconverter.

[0063] In a possible embodiment of the present invention, the filter 5 includes a filter inductor LF and a filter capacitor CF;

[0064] The first end of the filter inductor LF is electrically connected to the cathode of the fourth diode D4, the second end of the filter inductor LF is electrically connected to the first end of the filter capacitor CF, and the second end of the filter capacitor CF is electrically connected to the middle part of the secondary winding of the first transformer T1.

[0065] It should be noted that the filter inductor LF and the filter capacitor CF are used to eliminate high-frequency switching ripples and provide high-quality inverter AC power to the load.

[0066] See also Figure 2To facilitate the analysis of the soft switching principle, the variable inductor unit is equivalent to a controllable current source Isource, the magnitude of which can be controlled by adjusting the magnitude of the variable inductor. The basic principle of soft switching of a single-phase sinusoidal inverter based on controllable inductance is as follows:

[0067] (1) Positive half-cycle mode

[0068] When the inverter output voltage is in the positive half-cycle, the first and third MOS transistors Q1 and Q3 are the leading arms, while the second and fourth MOS transistors Q2 and Q4 are the lagging arms. Ids1, Ids2, Ids3, and Ids4 represent the parasitic capacitance currents of the switching transistors, respectively. Ipp is the primary current of high-frequency transformer T1, Isource1 is the output current of variable inductor 1, Isource2 is the output current of variable inductor 2, and Iload is the load current. The equivalent circuits for each stage are shown in the figure.

[0069] Phase 1: Equivalent circuit such as Figure 3 As shown, during this phase, the second and fourth MOS transistors Q2 and Q4 operate in a dead-band state, both non-conducting. The third MOS transistor Q3 is conducting, the first MOS transistor Q1 is off, the cycloconverter bidirectional switch Q6 is on, and Q5 is off. The second MOS transistor Q2 achieves zero-voltage soft switching within the dead-band. The primary current Ipp of the high-frequency transformer T1 and the variable inductor output current Isource2 charge the parasitic capacitor C4 and discharge the parasitic capacitor C2, releasing the charge on the parasitic capacitor before the second MOS transistor Q2 turns on, achieving soft switching. In the positive half-cycle mode, the second and fourth MOS transistors Q2 and Q4 are lagging arms, making soft switching difficult. Therefore, in this phase, the variable inductor 2 can be appropriately reduced to increase Isource2. This increase in Isource2 helps the lagging arm switch, the second MOS transistor Q2, achieve soft switching.

[0070] Phase 2: Equivalent circuit such as Figure 4 As shown, during this phase, the first and third MOS transistors Q1 and Q3 operate in a dead-band state, both non-conducting. The second MOS transistor Q2 is conducting, the fourth MOS transistor Q4 is off, the cycloconverter bidirectional switch Q6 is on, and Q5 is off. The first MOS transistor Q1 achieves zero-voltage soft-turn-on within the dead-band. The primary current Ipp of the high-frequency transformer T1 and the variable inductor output current Isource1 charge the parasitic capacitor C3 and discharge the parasitic capacitor C1, releasing the charge before the first MOS transistor Q1 turns on, achieving soft switching. In the positive half-cycle mode, the first and third MOS transistors Q1 and Q3 are leading arms, making soft switching easier for the first MOS transistor Q1. Therefore, the variable inductor 1 can be appropriately increased to reduce Isource1 during this phase.

[0071] Phase 3: Equivalent circuit such as Figure 5As shown, during this phase, the second MOS transistor Q2 and the fourth MOS transistor Q4 operate in a dead-band state, both non-conducting. The first MOS transistor Q1 is conducting, the third MOS transistor Q3 is off, the cycloconverter bidirectional switch Q5 is on, and Q6 is off. The fourth MOS transistor Q4 achieves zero-voltage soft switching within the dead-band. The primary current Ipp of the high-frequency transformer T1 and the variable inductor output current Isource1 charge the parasitic capacitor C2 and discharge the parasitic capacitor C4, releasing the charge on the parasitic capacitor before the fourth MOS transistor Q4 turns on, achieving soft switching. In the positive half-cycle mode, the second and fourth MOS transistors Q2 and Q4 are lagging arms, making soft switching difficult. Therefore, in this phase, the variable inductor 2 can be appropriately reduced to increase Isource2. This increase in Isource2 helps the lagging arm switch, the fourth MOS transistor Q4, achieve soft switching.

[0072] Phase 4: Equivalent circuit such as Figure 6 As shown, during this phase, the first and third MOS transistors Q1 and Q3 operate in a dead-band state, both non-conducting. The fourth MOS transistor Q4 is conducting, the second MOS transistor Q2 is off, the cycloconverter's bidirectional switch Q5 is on, and Q6 is off. The third MOS transistor Q3 achieves zero-voltage soft-turn-on within the dead-band. The primary current Ipp of the high-frequency transformer T1 and the variable inductor output current Isource charge the parasitic capacitor C1 and discharge the parasitic capacitor C3, releasing the charge before the third MOS transistor Q3 turns on, achieving soft switching. In the positive half-cycle mode, the first and third MOS transistors Q1 and Q3 are leading arms, making soft switching easier for the third MOS transistor Q3. Therefore, the variable inductor 1 can be appropriately increased to reduce Isource1 during this phase.

[0073] (2) Negative half-cycle mode

[0074] When the inverter output voltage is in the negative half cycle, the first MOS transistor Q1 and the third MOS transistor Q3 are the lagging arms, and the second MOS transistor Q2 and the fourth MOS transistor Q4 are the leading arms. The soft switching principle of the working mode is the same as that of the positive half cycle, so it will not be repeated here.

[0075] Analysis of the operating states at each stage of the circuit demonstrates that soft switching of all switches in the phase-shifted full-bridge can be achieved by adjusting the values ​​of the two variable inductors. Furthermore, the variable inductors can be implemented using only a conventional high-frequency transformer. Finally, the circuit topology effectively suppresses circulating reactive current by introducing diodes VD1 and VD2. Due to these characteristics, the proposed soft-switching circuit for a single-phase sinusoidal inverter based on controllable inductors achieves higher power conversion efficiency.

[0076] A second embodiment of the present invention provides a wide-range soft-switching full-bridge inverter device based on controllable inductance, including a controller and a wide-range soft-switching full-bridge inverter circuit based on controllable inductance as described in any one of the above items, wherein the controller is electrically connected to the control end of the first variable inductance unit 1, the control end of the second variable inductance unit 2, the control end of the phase-shifted full-bridge converter 3, and the control end of the cycloconverter 4.

[0077] The present invention provides a wide-range soft-switching full-bridge inverter circuit and device based on controllable inductance. The circuit and device change the self-inductance values ​​of the first variable inductance unit 1 and the second variable inductance unit 2 during the process of inverting the DC power supply module by the phase-shifted full-bridge converter 3 and the cycloconverter 4, thereby achieving soft switching of the phase-shifted full-bridge converter 3, thereby reducing the switching loss of the inverter during operation and improving the inverter efficiency.

[0078] The above are only preferred embodiments of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention.

Claims

1. A wide range soft switching full-bridge inverter circuit based on controllable inductance, characterized in that: include: A DC power supply module, a circulating current suppression circuit, a first variable inductance unit, a second variable inductance unit, a phase-shifted full-bridge converter, a first transformer, a cycloconverter, and a filter; The circulating current suppression circuit is connected to both ends of the DC power supply module, the output end of the DC power supply module is electrically connected to the input end of the phase-shifted full-bridge converter, the output end of the phase-shifted full-bridge converter is electrically connected to the primary winding of the first transformer, the secondary winding of the first transformer is electrically connected to the input end of the cycloconverter, the output end of the cycloconverter is connected to the input end of the filter, and the output end of the filter is connected to the load. A first end of the first variable inductor unit is electrically connected to a midpoint of the circulating current suppression circuit, a second end of the first variable inductor unit is electrically connected to a midpoint of one bridge arm of the phase-shifted full-bridge converter, a first end of the second variable inductor unit is electrically connected to the midpoint of the circulating current suppression circuit, and a second end of the second variable inductor unit is electrically connected to a midpoint of the other bridge arm of the phase-shifted full-bridge converter; The first variable inductor unit and the second variable inductor unit are configured to adjust their own inductance according to the switching signal; The phase-shifted full-bridge converter is configured to achieve soft switching during a sinusoidal wave inversion process according to the varying inductance value of the first variable inductor unit and the varying inductance value of the second variable inductor unit.

2. A wide range soft switching full-bridge inverter circuit based on controllable inductance according to claim 1, characterized in that: The first variable inductor unit includes: a second transformer, a first excitation inductor, a first leakage inductor, and a first bidirectional switch tube; The middle part of the circulating current suppression circuit is connected to the first end of the primary winding of the second transformer through the first leakage inductor, the second end of the primary winding of the second transformer is electrically connected to the midpoint of one of the bridge arms of the phase-shifted full-bridge converter, the first excitation inductor is connected to both ends of the primary winding of the second transformer, and the first bidirectional switch tube is connected to both ends of the secondary winding of the second transformer.

3. A wide range soft switching full-bridge inverter circuit based on controllable inductance according to claim 2, characterized in that: The second variable inductor unit includes: a third transformer, a second excitation inductor, a second leakage inductor, and a second bidirectional switch tube; The middle part of the circulating current suppression circuit is connected to the first end of the primary winding of the third transformer through the second leakage inductance, the second end of the primary winding of the third transformer is electrically connected to the midpoint of the other bridge arm of the phase-shifted full-bridge converter, the second excitation inductor is connected to both ends of the primary winding of the third transformer, and the second bidirectional switch tube is connected to both ends of the secondary winding of the third transformer.

4. A wide range soft switching full-bridge inverter circuit based on controllable inductance according to claim 3, characterized in that: The phase-shifted full-bridge converter includes a first MOS transistor, a second MOS transistor, a third MOS transistor, a fourth MOS transistor, a first capacitor, a second capacitor, a third capacitor, and a fourth capacitor; The D pole of the first MOS transistor is electrically connected to the D pole of the second MOS transistor, the S pole of the first MOS transistor is electrically connected to the D pole of the third MOS transistor, the S pole of the second MOS transistor is electrically connected to the D pole of the fourth MOS transistor, the S pole of the third MOS transistor is electrically connected to the S pole of the fourth MOS transistor, the first capacitor is electrically connected to the S pole and D pole of the first MOS transistor, the second capacitor is electrically connected to the S pole and D pole of the second MOS transistor, the third capacitor is electrically connected to the S pole and D pole of the third MOS transistor, and the fourth capacitor is electrically connected to the S pole and D pole of the fourth MOS transistor; The S pole of the first MOS transistor is electrically connected to the second end of the primary winding of the second transformer, the S pole of the first MOS transistor is electrically connected to the first end of the primary winding of the first transformer, the S pole of the second MOS transistor is electrically connected to the second end of the primary winding of the third transformer, and the S pole of the second MOS transistor is electrically connected to the second end of the primary winding of the first transformer.

5. The wide-range soft-switching full-bridge inverter circuit based on controllable inductance according to claim 4, characterized in that: The cycloconverter includes a first diode, a second diode, a third diode, a fourth diode, a fifth diode, a sixth diode, a seventh diode, an eighth diode, a fifth MOS transistor, and a sixth MOS transistor; The cathode of the first diode is electrically connected to the cathode of the second diode and the D electrode of the fifth MOS transistor, the anode of the third diode is electrically connected to the anode of the fourth diode and the S electrode of the fifth MOS transistor, the anode of the first diode is electrically connected to the cathode of the third diode, and the anode of the second diode is electrically connected to the cathode of the fourth diode; The cathode of the fifth diode is electrically connected to the cathode of the sixth diode and the D electrode of the sixth MOS transistor, the anode of the seventh diode is electrically connected to the anode of the eighth diode and the S electrode of the sixth MOS transistor, the anode of the fifth diode is electrically connected to the cathode of the seventh diode, and the anode of the sixth diode is electrically connected to the cathode of the eighth diode; The anode of the first diode is electrically connected to the first end of the secondary winding of the first transformer, and the anode of the fifth diode is electrically connected to the second end of the secondary winding of the first transformer.

6. A wide range soft switching full-bridge inverter circuit based on controllable inductance according to claim 5, characterized in that: The filter includes a filter inductor and a filter capacitor; The first end of the filter inductor is electrically connected to the cathode of the fourth diode, the second end of the filter inductor is electrically connected to the first end of the filter capacitor, and the second end of the filter capacitor is electrically connected to the middle portion of the secondary winding of the first transformer.

7. The wide-range soft-switching full-bridge inverter circuit based on controllable inductance according to claim 2, characterized in that: The first bidirectional switch includes a ninth diode, a tenth diode, an eleventh diode, a twelfth diode, and a seventh MOS tube; The cathode of the ninth diode is electrically connected to the cathode of the tenth diode and the D electrode of the seventh MOS transistor, the anode of the eleventh diode is electrically connected to the anode of the twelfth diode and the S electrode of the seventh MOS transistor, the anode of the ninth diode is electrically connected to the cathode of the eleventh diode, and the anode of the tenth diode is electrically connected to the cathode of the twelfth diode; The anode of the ninth diode is electrically connected to the first end of the secondary winding of the second transformer, and the cathode of the twelfth diode is electrically connected to the second end of the secondary winding of the second transformer.

8. The wide-range soft-switching full-bridge inverter circuit based on controllable inductance according to claim 3, characterized in that: The second bidirectional switch includes a thirteenth diode, a fourteenth diode, a fifteenth diode, a sixteenth diode, and an eighth MOS tube; The cathode of the thirteenth diode is electrically connected to the cathode of the fourteenth transistor and the D electrode of the eighth MOS transistor, the anode of the fifteenth diode is electrically connected to the anode of the sixteenth diode and the S electrode of the eighth MOS transistor, the anode of the thirteenth diode is electrically connected to the cathode of the fifteenth diode, and the anode of the fourteenth diode is electrically connected to the cathode of the sixteenth diode; The anode of the thirteenth diode is electrically connected to the first end of the secondary winding of the third transformer, and the cathode of the sixteenth diode is electrically connected to the second end of the secondary winding of the third transformer.

9. A wide range soft switching full-bridge inverter device based on controllable inductance, characterized in that: The invention comprises a controller and a wide-range soft-switching full-bridge inverter circuit based on controllable inductance according to any one of claims 1 to 8, wherein the controller is electrically connected to the control end of the first variable inductance unit, the control end of the second variable inductance unit, the control end of the phase-shifted full-bridge converter, and the control end of the cycloconverter.

Images