阅读说明：本技术 高频谐振逆变器 (High frequency resonance inverter ) 是由 汪洪亮 陈鑫跃 李奎 岳秀梅 罗安 于 2020-06-08 设计创作，主要内容包括：本发明提供了一种高频谐振逆变器。所述逆变器包括逆变电路和谐振电路；所述逆变电路分别与所述谐振电路和外部的直流电源连接,还连接第一若干控制端,适于在所述第一若干控制端接入的控制信号的控制下,将直流电源电压转换成对称方波电压,并将所述对称方波电压输出给所述谐振电路；所述谐振电路与外部的负载连接,还连接第二若干控制端,适于在所述第二若干控制端接入的控制信号的控制下,所述谐振电路的电压增益可调控,所述谐振电路将所述对称方波电压转换成预期的交流电压输出给负载。本发明提供的逆变器可以动态调整电压增益。(The invention provides a high-frequency resonance inverter. The inverter comprises an inverter circuit and a resonant circuit; the inverter circuit is respectively connected with the resonant circuit and an external direct-current power supply, is also connected with a first plurality of control ends, is suitable for converting direct-current power supply voltage into symmetrical square-wave voltage under the control of control signals accessed by the first plurality of control ends, and outputs the symmetrical square-wave voltage to the resonant circuit; the resonant circuit is connected with an external load and is also connected with a plurality of second control ends, the voltage gain of the resonant circuit can be regulated and controlled under the control of control signals accessed by the plurality of second control ends, and the resonant circuit converts the symmetrical square wave voltage into expected alternating voltage and outputs the expected alternating voltage to the load. The inverter provided by the invention can dynamically adjust the voltage gain.)

1. A high-frequency resonance inverter is characterized by comprising an inverter circuit and a resonance circuit;

the inverter circuit is respectively connected with the resonant circuit and an external direct-current power supply, is also connected with a first plurality of control ends, is suitable for converting direct-current power supply voltage into symmetrical square-wave voltage under the control of control signals accessed by the first plurality of control ends, and outputs the symmetrical square-wave voltage to the resonant circuit;

the resonant circuit is connected with an external load and is also connected with a plurality of second control ends, the voltage gain of the resonant circuit can be regulated and controlled under the control of control signals accessed by the plurality of second control ends, and the resonant circuit converts the symmetrical square wave voltage into expected alternating voltage and outputs the expected alternating voltage to the load.

2. The high frequency resonant inverter of claim 1, wherein the resonant circuit comprises a controllable capacitance element; the controllable capacitor unit at least comprises a bidirectional controllable switch circuit and a controllable capacitor; the first end of the bidirectional controllable switch circuit is connected with the first end of the controllable capacitor and is used as the first end of the controllable capacitor unit; the second end of the bidirectional controllable switch circuit is connected with the second end of the controllable capacitor and is used as the second end of the controllable capacitor unit;

the bidirectional controllable switch circuit is also connected with the second plurality of control ends, and under the control of control signals accessed by the second plurality of control ends, the controllable capacitor unit provides four working modes, so that the equivalent capacitance value of the controllable capacitor in one switching period can be regulated and controlled:

in a first working mode, current flows from the first end of the controllable capacitor unit to the second end of the controllable capacitor unit through the bidirectional controllable switch circuit, and the controllable capacitor does not work; in a second working mode, current flows from the first end of the controllable capacitor unit to the second end of the controllable capacitor unit through the controllable capacitor, and the bidirectional controllable switch circuit is turned off;

in a third working mode, current flows from the second end of the controllable capacitor unit to the first end of the controllable capacitor unit through the bidirectional controllable switch circuit, and the controllable capacitor does not work;

in a fourth working mode, the current flows from the second end of the controllable capacitance unit to the first end of the controllable capacitance unit through the controllable capacitance, and the bidirectional controllable switch circuit is turned off.

3. The high frequency resonant inverter of claim 2, wherein the bidirectional controllable switching circuit comprises two switching tubes connected together in series; the two switching tubes are connected with a diode in parallel in a reverse direction; the two switch tubes are arranged in opposite directions.

4. The high frequency resonant inverter according to claim 2 or 3, characterized in that the resonant circuit further comprises a first inductance and a first capacitance; wherein the content of the first and second substances,

the first end of the first inductor is connected with the first end of the inverter circuit, and the second end of the first inductor is connected with the first end of the controllable capacitance unit;

the second end of the controllable capacitor unit is connected with the first end of the first capacitor, and the second end of the first capacitor is connected with the third end of the inverter circuit;

and two ends of the first capacitor are used as two output ends of the inverter and are respectively connected with two ends of the load.

5. The high frequency resonant inverter according to claim 2 or 3, characterized in that the resonant circuit further comprises a first inductance, a second inductance and a first capacitance; wherein the content of the first and second substances,

the first end of the first inductor is connected with the first end of the inverter circuit, and the second end of the first inductor is connected with the first end of the controllable capacitance unit;

the second end of the controllable capacitor unit is respectively connected with the first end of the second inductor and the first end of the first capacitor;

the second end of the second inductor and the second end of the first capacitor are respectively connected with the third end of the inverter circuit;

and two ends of the first capacitor are used as two output ends of the inverter and are respectively connected with two ends of the load.

6. The high frequency resonant inverter according to claim 2 or 3, characterized in that the resonant circuit further comprises a first inductance, a second inductance and a first capacitance; wherein the content of the first and second substances,

the first end of the first inductor is connected with the first end of the inverter circuit, and the second end of the first inductor is connected with the first end of the controllable capacitance unit;

the second end of the controllable capacitance unit is connected with the first end of the first capacitor;

the second end of the first capacitor is connected with the first end of the second inductor;

the second end of the second inductor is connected with the third end of the inverter circuit;

and the first end of the first capacitor and the second end of the second inductor are used as two output ends of the inverter and are respectively connected with two ends of the load.

7. The high frequency resonant inverter according to claim 2 or 3, characterized in that the resonant circuit further comprises a first inductance, a second inductance and a first capacitance; wherein the content of the first and second substances,

the first end of the first inductor is connected with the first end of the inverter circuit, and the second end of the first inductor is connected with the first end of the first capacitor;

the second end of the first capacitor is connected with the first end of the controllable capacitor unit;

the second end of the controllable capacitance unit is connected with the first end of the second inductor;

the second end of the second inductor is connected with the third end of the inverter circuit;

and the first end of the controllable capacitor unit and the second end of the second inductor are used as two output ends of the inverter and are respectively connected with two ends of the load.

8. A high frequency resonant inverter as claimed in claim 1, wherein the resonant circuit comprises a controllable inductance unit; the controllable inductance unit at least comprises a bidirectional controllable switch circuit and a controllable inductance which are connected in series; wherein the content of the first and second substances,

the first end of the bidirectional controllable switch circuit is connected with the second end of the controllable inductor, the first end of the controllable inductor is used as the first end of the controllable inductor unit, and the second end of the bidirectional controllable switch circuit is used as the second end of the controllable inductor unit;

the bidirectional controllable switch circuit is also connected with the second plurality of control ends, and under the control of control signals accessed by the second plurality of control ends, the controllable inductance unit provides three working modes, so that the equivalent inductance value of the controllable inductance in one switching period can be regulated and controlled:

in a first working mode, current flows from the first end of the controllable inductance unit to the second end of the controllable inductance unit through the controllable inductance and the bidirectional controllable switch circuit in sequence;

in a second working mode, the bidirectional controllable switching circuit is turned off, and no current flows through the controllable inductance unit;

in a third working mode, the current flows from the second end of the controllable inductance unit to the first end of the controllable inductance unit through the bidirectional controllable switch circuit and the controllable inductance in sequence.

9. The high frequency resonant inverter of claim 8, wherein the bidirectional controllable switching circuit comprises two switching tubes connected together in series; the two switching tubes are connected with a diode in parallel in a reverse direction; the two switch tubes are arranged in opposite directions.

10. The high frequency resonant inverter according to claim 8 or 9, characterized in that the resonant circuit further comprises a first inductance and a first capacitance; wherein the content of the first and second substances,

the first end of the first inductor is connected with the first end of the inverter circuit, and the second end of the first inductor is connected with the first end of the controllable inductor unit;

the second end of the controllable inductance unit is connected with the third end of the inverter circuit;

a first end of the first capacitor is connected with a first end of the controllable inductance unit, and a second end of the first capacitor is connected with a second end of the controllable inductance unit;

and two ends of the first capacitor are used as two output ends of the inverter and are respectively connected with two ends of the load.

11. The high frequency resonant inverter according to claim 8 or 9, characterized in that the resonant circuit further comprises a first capacitance, a first inductance and a second capacitance; wherein the content of the first and second substances,

the first end of the first inductor is connected with the first end of the inverter circuit, and the second end of the first inductor is connected with the first end of the first capacitor;

the second end of the first capacitor is respectively connected with the first end of the controllable inductance unit and the first end of the second capacitor;

the second end of the controllable inductance unit and the second end of the second capacitor are respectively connected with the third end of the inverter circuit;

and the first end and the second end of the controllable inductance unit are used as two output ends of the inverter and are respectively connected with two ends of the load.

12. The high frequency resonant inverter according to claim 8 or 9, characterized in that the resonant circuit further comprises a first capacitance, a first inductance and a second capacitance; wherein the content of the first and second substances,

the first end of the controllable inductance unit and the first end of the first capacitor are respectively connected with the first end of the inverter circuit;

the second end of the controllable inductance unit and the second end of the first capacitor are respectively connected with the first end of the second capacitor;

the second end of the second capacitor is connected with the first end of the first inductor;

the second end of the first inductor is connected with the third end of the inverter circuit;

and the first end of the second capacitor and the second end of the first inductor are used as two output ends of the inverter and are respectively connected with two ends of the load.

13. The high frequency resonant inverter according to claim 8 or 9, characterized in that the resonant circuit further comprises a first capacitance, a first inductance and a second capacitance; wherein the content of the first and second substances,

the first end of the first capacitor and the first end of the first inductor are respectively connected with the first end of the inverter circuit;

the second end of the first capacitor and the second end of the first inductor are respectively connected with the first end of the second capacitor, and the second end of the first capacitor and the second end of the first inductor are respectively connected with the first end of the controllable inductor unit;

the second end of the second capacitor and the second end of the controllable inductance unit are respectively connected with the third end of the inverter circuit;

and the first end and the second end of the controllable inductance unit are used as two output ends of the inverter and are respectively connected with two ends of the load.

Technical Field

The invention relates to the technical field of inverters, in particular to a high-frequency resonance inverter.

Background

The SPWM inverter is based on the area equivalent principle, i.e. when the narrow pulses with the same impulse and different shapes are added to the link with inertia, the effect is basically the same, the pulse width changes according to the sine rule and the PWM waveform with the sine wave equivalent, i.e. the SPWM waveform, controls the on-off of the switch tube in the inverter circuit, so that the area of the output pulse voltage is equal to the area of the sine wave expected to be output in the corresponding interval, and the frequency and the amplitude of the output voltage of the inverter circuit can be adjusted by changing the frequency and the amplitude of the modulating wave.

Considering that a continuous function can be approximated or replaced by an infinite number of discrete functions, a sine wave can be replaced by a number of rectangular pulse waves of different amplitudes; a plurality of waveforms with equal width and unequal amplitude are divided on a sine half wave, and if the area of each rectangular wave is equal to the area of the sine wave in the corresponding time period, the combined area of the series of rectangular waves is equal to the area of the sine wave, namely, the equivalent effect is achieved.

The traditional SPWM type (pulse width modulation) inverter takes the area equivalent principle as the theoretical basis for control, the output state is limited by the switching frequency of a switching tube, and the high-frequency voltage output is difficult to realize. Moreover, due to the limitations of voltage stress and the like of the existing power electronic devices, the gain of the output voltage is difficult to be adjusted, and the application of the high-frequency converter is severely limited.

Disclosure of Invention

In view of the above-mentioned drawbacks in the prior art, the present invention provides a high frequency resonant inverter, which is used to solve some technical problems in the related art.

In a first aspect, an embodiment of the present invention provides a high-frequency resonant inverter, including an inverter circuit and a resonant circuit;

the inverter circuit is respectively connected with the resonant circuit and an external direct-current power supply, is also connected with a first plurality of control ends, is suitable for converting direct-current power supply voltage into symmetrical square-wave voltage under the control of control signals accessed by the first plurality of control ends, and outputs the symmetrical square-wave voltage to the resonant circuit;

the resonant circuit is connected with an external load and is also connected with a plurality of second control ends, the voltage gain of the resonant circuit can be regulated and controlled under the control of control signals accessed by the plurality of second control ends, and the resonant circuit converts the symmetrical square wave voltage into expected alternating voltage and outputs the expected alternating voltage to the load.

Optionally, the resonant circuit comprises a controllable capacitive element; the controllable capacitor unit at least comprises a bidirectional controllable switch circuit and a controllable capacitor; the first end of the bidirectional controllable switch circuit is connected with the first end of the controllable capacitor and is used as the first end of the controllable capacitor unit; the second end of the bidirectional controllable switch circuit is connected with the second end of the controllable capacitor and is used as the second end of the controllable capacitor unit;

the bidirectional controllable switch circuit is also connected with the second plurality of control ends, and under the control of control signals accessed by the second plurality of control ends, the controllable capacitor unit provides four working modes, so that the equivalent capacitance value of the controllable capacitor in one switching period can be regulated and controlled:

in a first working mode, current flows from the first end of the controllable capacitor unit to the second end of the controllable capacitor unit through the bidirectional controllable switch circuit, and the controllable capacitor does not work; in a second working mode, current flows from the first end of the controllable capacitor unit to the second end of the controllable capacitor unit through the controllable capacitor, and the bidirectional controllable switch circuit is turned off;

in a third working mode, current flows from the second end of the controllable capacitor unit to the first end of the controllable capacitor unit through the bidirectional controllable switch circuit, and the controllable capacitor does not work;

in a fourth working mode, the current flows from the second end of the controllable capacitance unit to the first end of the controllable capacitance unit through the controllable capacitance, and the bidirectional controllable switch circuit is turned off.

Optionally, the bidirectional controllable switching circuit comprises two switching tubes connected together in series; the two switching tubes are connected with a diode in parallel in a reverse direction; the two switch tubes are arranged in opposite directions.

Optionally, the resonant circuit further comprises a first inductor and a first capacitor; wherein the content of the first and second substances,

the first end of the first inductor is connected with the first end of the inverter circuit, and the second end of the first inductor is connected with the first end of the controllable capacitance unit;

the second end of the controllable capacitor unit is connected with the first end of the first capacitor, and the second end of the first capacitor is connected with the third end of the inverter circuit;

and two ends of the first capacitor are used as two output ends of the inverter and are respectively connected with two ends of the load.

Optionally, the resonant circuit further comprises a first inductor, a second inductor and a first capacitor; wherein the content of the first and second substances,

the first end of the first inductor is connected with the first end of the inverter circuit, and the second end of the first inductor is connected with the first end of the controllable capacitance unit;

the second end of the controllable capacitor unit is respectively connected with the first end of the second inductor and the first end of the first capacitor;

the second end of the second inductor and the second end of the first capacitor are respectively connected with the third end of the inverter circuit;

and two ends of the first capacitor are used as two output ends of the inverter and are respectively connected with two ends of the load.

Optionally, the resonant circuit further comprises a first inductor, a second inductor and a first capacitor; wherein the content of the first and second substances,

the first end of the first inductor is connected with the first end of the inverter circuit, and the second end of the first inductor is connected with the first end of the controllable capacitance unit;

the second end of the controllable capacitance unit is connected with the first end of the first capacitor;

the second end of the first capacitor is connected with the first end of the second inductor;

the second end of the second inductor is connected with the third end of the inverter circuit;

and the first end of the first capacitor and the second end of the second inductor are used as two output ends of the inverter and are respectively connected with two ends of the load.

Optionally, the resonant circuit further comprises a first inductor, a second inductor and a first capacitor; wherein the content of the first and second substances,

the first end of the first inductor is connected with the first end of the inverter circuit, and the second end of the first inductor is connected with the first end of the first capacitor;

the second end of the first capacitor is connected with the first end of the controllable capacitor unit;

the second end of the controllable capacitance unit is connected with the first end of the second inductor;

the second end of the second inductor is connected with the third end of the inverter circuit;

and the first end of the controllable capacitor unit and the second end of the second inductor are used as two output ends of the inverter and are respectively connected with two ends of the load.

Optionally, the resonant circuit comprises a controllable inductance unit; the controllable inductance unit at least comprises a bidirectional controllable switch circuit and a controllable inductance which are connected in series; wherein the content of the first and second substances,

the first end of the bidirectional controllable switch circuit is connected with the second end of the controllable inductor, the first end of the controllable inductor is used as the first end of the controllable inductor unit, and the second end of the bidirectional controllable switch circuit is used as the second end of the controllable inductor unit;

the bidirectional controllable switch circuit is also connected with the second plurality of control ends, and under the control of control signals accessed by the second plurality of control ends, the controllable inductance unit provides three working modes, so that the equivalent inductance value of the controllable inductance in one switching period can be regulated and controlled:

in a first working mode, current flows from the first end of the controllable inductance unit to the second end of the controllable inductance unit through the controllable inductance and the bidirectional controllable switch circuit in sequence;

in a second working mode, the bidirectional controllable switching circuit is turned off, and no current flows through the controllable inductance unit;

in a third working mode, the current flows from the second end of the controllable inductance unit to the first end of the controllable inductance unit through the bidirectional controllable switch circuit and the controllable inductance in sequence.

Optionally, the bidirectional controllable switching circuit comprises two switching tubes connected together in series; the two switching tubes are connected with a diode in parallel in a reverse direction; the two switch tubes are arranged in opposite directions.

Optionally, the resonant circuit further comprises a first inductor and a first capacitor; wherein the content of the first and second substances,

the first end of the first inductor is connected with the first end of the inverter circuit, and the second end of the first inductor is connected with the first end of the controllable inductor unit;

the second end of the controllable inductance unit is connected with the third end of the inverter circuit;

a first end of the first capacitor is connected with a first end of the controllable inductance unit, and a second end of the first capacitor is connected with a second end of the controllable inductance unit;

and two ends of the first capacitor are used as two output ends of the inverter and are respectively connected with the two loads.

Optionally, the resonant circuit further comprises a first capacitor, a first inductor and a second capacitor; wherein the content of the first and second substances,

the first end of the first inductor is connected with the first end of the inverter circuit, and the second end of the first inductor is connected with the first end of the first capacitor;

the second end of the first capacitor is respectively connected with the first end of the controllable inductance unit and the first end of the second capacitor;

the second end of the controllable inductance unit and the second end of the second capacitor are respectively connected with the third end of the inverter circuit;

and the first end and the second end of the controllable inductance unit are used as two output ends of the inverter and are respectively connected with two ends of the load.

Optionally, the resonant circuit further comprises a first capacitor, a first inductor and a second capacitor; wherein the content of the first and second substances,

the first end of the controllable inductance unit and the first end of the first capacitor are respectively connected with the first end of the inverter circuit;

the second end of the controllable inductance unit and the second end of the first capacitor are respectively connected with the first end of the second capacitor;

the second end of the second capacitor is connected with the first end of the first inductor;

the second end of the first inductor is connected with the third end of the inverter circuit;

and the first end of the second capacitor and the second end of the first inductor are used as two output ends of the inverter and are respectively connected with two ends of the load.

Optionally, the resonant circuit further comprises a first capacitor, a first inductor and a second capacitor; wherein the content of the first and second substances,

the first end of the first capacitor and the first end of the first inductor are respectively connected with the first end of the inverter circuit;

the second end of the first capacitor and the second end of the first inductor are respectively connected with the first end of the second capacitor, and the second end of the first capacitor and the second end of the first inductor are respectively connected with the first end of the controllable inductor unit;

the second end of the second capacitor and the second end of the controllable inductance unit are respectively connected with the third end of the inverter circuit;

and the first end and the second end of the controllable inductance unit are used as two output ends of the inverter and are respectively connected with two ends of the load.

According to the technical scheme, the high-frequency resonant inverter in the embodiment of the invention comprises an inverter circuit and a resonant circuit; the inverter circuit is respectively connected with the resonant circuit and an external direct-current power supply and is used for converting the direct-current power supply into symmetrical square-wave voltage according to a first control signal and outputting the symmetrical square-wave voltage to the resonant circuit. The preset carrier frequency is the same as the frequency of the modulation wave; the resonant circuit is connected with an external load, and is used for converting the symmetrical square wave voltage into an expected alternating voltage and outputting the expected alternating voltage to the load, wherein the voltage gain of the resonant circuit can be regulated and controlled under the control of a second control signal. In the embodiment, the carrier frequency and the modulation wave frequency are the same, so that the requirement of high-power high-frequency sinusoidal power supply can be met, and the voltage gain can be dynamically adjusted through the resonant circuit.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic circuit diagram of a high-frequency resonant inverter according to an embodiment of the present invention.

Fig. 2 is a schematic circuit diagram of a controllable capacitance unit according to an embodiment of the present invention.

Fig. 3 is a circuit diagram of a controllable capacitance unit according to an embodiment of the present invention.

Fig. 4(a) to 4(d) are equivalent circuit diagrams of the controllable capacitance unit shown in fig. 3 in four operating modes.

Fig. 5 is a schematic circuit diagram of a controllable inductance unit according to an embodiment of the present invention.

Fig. 6 is a circuit diagram of a controllable inductance unit according to an embodiment of the present invention.

Fig. 7(a) -7 (c) are equivalent circuit diagrams of the controllable inductance unit shown in fig. 6 in two working modes.

Fig. 8 is a circuit diagram of a high-frequency resonant inverter implemented based on a controllable capacitor unit according to an embodiment of the present invention.

Fig. 9 is a circuit diagram of a high-frequency resonant inverter implemented based on a controllable capacitance unit according to another embodiment of the present invention.

Fig. 10 is a circuit diagram of a high-frequency resonant inverter implemented based on a controllable capacitance unit according to another embodiment of the present invention.

Fig. 11 is a circuit diagram of a high-frequency resonant inverter implemented based on a controllable capacitance unit according to another embodiment of the present invention.

Fig. 12 is a circuit diagram of a high-frequency resonant inverter implemented based on a controllable inductance unit according to another embodiment of the present invention.

Fig. 13 is a circuit diagram of a high-frequency resonant inverter implemented based on a controllable inductance unit according to another embodiment of the present invention.

Fig. 14 is a circuit diagram of a high-frequency resonant inverter implemented based on a controllable inductance unit according to another embodiment of the present invention.

Fig. 15 is a circuit diagram of a high-frequency resonant inverter implemented based on a controllable inductance unit according to another embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In view of the problems in the related art, embodiments of the present invention provide a high frequency resonant inverter, which is based on the idea of adding a resonant circuit to an inverter circuit, outputting an expected ac voltage to a load by adjusting a voltage gain of the resonant circuit, and dynamically adjusting an output voltage gain.

The symmetrical square wave voltage output from the inverter circuit is subjected to fourier transform to be decomposed into a plurality of sine waves of different frequencies, wherein the sine waves include a sine wave of a lowest frequency which coincides with the switching frequency of the switching device, and a sine wave of a frequency which is a multiple of the switching frequency and is greater than the switching frequency. In addition, the LC resonance has the following characteristics: the LC series resonance impedance is zero (equivalent to a short circuit) and the LC parallel impedance is infinite (equivalent to an open circuit), and a resonance circuit is constructed based on this so that the output gain for the sine wave of the target frequency tends to be maximum, and the output gain for the sine wave of other frequencies obtained by fourier transform decomposition tends to be zero, and the sine wave of the target frequency can be output to the load, but the sine wave of the non-target frequency cannot be output to the load.

The inverter circuit is respectively connected with the resonant circuit and an external direct-current power supply, is also connected with a plurality of first control ends, is suitable for converting direct-current power supply voltage into symmetrical square-wave voltage under the control of control signals accessed by the plurality of first control ends, and outputs the symmetrical square-wave voltage to the resonant circuit.

The resonant circuit is connected with an external load and is also connected with a plurality of second control ends, the voltage gain of the resonant circuit can be regulated and controlled under the control of control signals accessed by the plurality of second control ends, and the resonant circuit converts the symmetrical square wave voltage into expected alternating voltage and outputs the expected alternating voltage to the load.

The frequency of the modulation wave of the inverter circuit is preset to be equal to the carrier frequency, so that the frequency of the output symmetrical square wave voltage is equal to the switching frequency of the inverter circuit. The resonance circuit utilizes the characteristic of LC resonance to enable sine waves with the frequency equal to the switching frequency of the inverter circuit obtained by Fourier transform decomposition of the symmetrical square wave voltage to be output to the load, and sine waves with the frequency not equal to the switching frequency of the inverter circuit cannot be output to the load. Therefore, the inverter provided by the invention can output high-frequency sine wave voltage with the frequency equal to the switching frequency.

Referring to fig. 2, the resonant circuit comprises a controllable capacitive unit; the controllable capacitor unit at least comprises a bidirectional controllable switch circuit and a controllable capacitor; the first end of the bidirectional controllable switch circuit is connected with the first end of the controllable capacitor and is used as the first end of the controllable capacitor unit; and the second end of the bidirectional controllable switch circuit is connected with the second end of the controllable capacitor and is used as the second end of the controllable capacitor unit. The bidirectional controllable switch circuit is also connected with the second plurality of control ends, and under the control of control signals accessed by the second plurality of control ends, the controllable capacitor unit provides four working modes, so that the equivalent capacitance value of the controllable capacitor in one switching period can be regulated and controlled:

in a first working mode, current flows from the first end of the controllable capacitor unit to the second end of the controllable capacitor unit through the bidirectional controllable switch circuit, and the controllable capacitor does not work; in a second working mode, current flows from the first end of the controllable capacitor unit to the second end of the controllable capacitor unit through the controllable capacitor, and the bidirectional controllable switch circuit is turned off;

in a third working mode, current flows from the second end of the controllable capacitor unit to the first end of the controllable capacitor unit through the bidirectional controllable switch circuit, and the controllable capacitor does not work;

in a fourth working mode, the current flows from the second end of the controllable capacitance unit to the first end of the controllable capacitance unit through the controllable capacitance, and the bidirectional controllable switch circuit is turned off.

Alternatively, the first and second electrodes may be,

referring to fig. 5, the resonant circuit comprises a controllable inductance unit comprising at least a bidirectional controllable switching circuit and a controllable inductance connected in series. The first end of the bidirectional controllable switch circuit is connected with the second end of the controllable inductor, the first end of the controllable inductor is used as the first end of the controllable inductor unit, and the second end of the bidirectional controllable switch circuit is used as the second end of the controllable inductor unit. The bidirectional controllable switch circuit is also connected with the second plurality of control ends, and under the control of control signals accessed by the second plurality of control ends, the controllable inductance unit provides three working modes, so that the equivalent inductance value of the controllable inductance in one switching period can be regulated and controlled:

in a first working mode, current flows from the first end of the controllable inductance unit to the second end of the controllable inductance unit through the controllable inductance and the bidirectional controllable switch circuit in sequence;

in a second working mode, the bidirectional controllable switching circuit is turned off, and no current flows through the controllable inductance unit;

in a third working mode, the current flows from the second end of the controllable inductance unit to the first end of the controllable inductance unit through the bidirectional controllable switch circuit and the controllable inductance in sequence. Another embodiment of the present invention provides a specific circuit diagram of the controllable capacitance unit and the controllable inductance unit, and the resonant circuit can be implemented based on the provided controllable capacitance unit or the provided controllable inductance unit and other related devices.

It should be noted that, for convenience of description, a switching MOSFET is used as a representative controllable (on and off) switch in the present invention, but the switch in the present invention is not limited to the MOSFET. An N-channel MOSFET will be described as an example. The first terminal of the N-channel MOSFET is a drain, the second terminal is a source, and the control terminal is a gate. The control terminal of each switch in the invention applies a driving control signal. For brevity, further description is omitted. The switch in the present invention can also be implemented by using other controllable switch device besides MOSFET, such as IGBT.

Note that a diode is used to represent the one-way conduction element, but the one-way conduction element in the present invention is not limited to a diode. The anode of the diode is the anode and the cathode is the cathode. The one-way conduction element in the invention can also adopt other one-way conduction devices besides diodes. The terms "first", "second", and the like are used only for distinguishing the respective devices, and do not limit the order of the respective devices.

Referring to fig. 3, the controllable capacitance unit includes a controllable capacitance Cs and a first switch tube S connected in series₁A second switch tube S₂. First switch tube S₁A second switch tube S₂Are all reversely connected with a diode in parallel, and the first switch tube S₁A second switch tube S₂And connecting the two opposite ends. Specifically, the first switch tube S₁As a first terminal of a controllable capacitive unit (denoted by reference sign a), a first switching tube S₁Second terminal and second switch tube S₂Is connected to the second end of the first housing. A second switch tube S₂As the second terminal of the controllable capacitance unit (right end in fig. 3)Indicated by reference B). The first end (left end in fig. 3) of the controllable capacitor Cs and the first switch tube S₁Is connected with the first end of the controllable capacitor Cs, and the second end of the controllable capacitor Cs is connected with the second switch tube S₂Is connected to the first end of the first housing. First switch tube S₁Control terminal and second switch tube S₂The control terminals of the first and second switches are respectively connected with the controller so as to access the second control signal.

In a switching cycle, the controllable capacitance unit provides four operating modes under the control of the accessed second control signal, specifically as follows:

the first working mode is as follows: first switch tube S₁Conducting the first switch tube S₁The anti-parallel diode is turned off, and the second switch tube S₂Off, the second switching tube S₂The anti-parallel diode is turned on and the equivalent circuit is as shown in fig. 4 (a). At this time, the current flows from A to B, and passes through the first switch tube S in turn₁And a second switching tube S₂An anti-parallel diode. A switching branch (S) connected in parallel with the controllable capacitance Cs₁、S₂Anti-parallel diode) corresponds to a short circuit, so the controllable capacitor Cs does not work, i.e. the equivalent capacitance of the controllable capacitor Cs is infinite at this time.

Working mode two, the first switch tube S₁A second switch tube S₂And their anti-parallel diodes are all turned off, the controllable capacitance Cs operates, and the equivalent circuit is shown in fig. 4 (c). Current flows from a to B via the controllable capacitance Cs. The equivalent capacitance value of the controllable capacitance Cs is then its own capacitance value.

Working mode III, a first switch tube S₁Turn off, first switch tube S₁The anti-parallel diode is conducted, and the second switch tube S₂Conducting the second switch tube S₂The anti-parallel diode is turned off and the equivalent circuit is as shown in fig. 4 (c). At this time, the current flows from B to A, and passes through the second switch tube and the first switch tube S in turn₁An anti-parallel diode. . A switching branch (S) connected in parallel with the controllable capacitance Cs₂、S₁Anti-parallel diode) corresponds to a short circuit, so the controllable capacitor Cs does not work, i.e. the equivalent capacitance of the controllable capacitor Cs is infinite at this time.

Working mode four, firstSwitch tube S₁A second switch tube S₂And their anti-parallel diodes are all turned off, the controllable capacitance Cs operates, and the equivalent circuit is shown in fig. 4 (d). Current flows from B to a via the controllable capacitance Cs. The equivalent capacitance value of the controllable capacitance Cs is then its own capacitance value.

According to the analysis of the four working modes, the equivalent capacitance values under the mode one and the mode three are infinite, and the equivalent capacitance values under the mode two and the mode four are the capacitance values of the controllable capacitor. By controlling the switching tube S₁And S₂And when the controllable capacitor unit shown in fig. 3 is turned on or off, the controllable capacitor unit works alternately in a certain combination mode under the four working modes, so that the required equivalent capacitance value is obtained. The specific combination of the four operating modes depends on the specific modulation strategy adopted in practical application, and is not described herein.

By combining the four operating modes of the controllable capacitive unit in a certain order and controlling the switching tube S in each mode₁And S₂And the time of switching on or off regulates and controls the equivalent capacitance value of the controllable capacitance unit in a switching period, so as to regulate and control the impedance value of the controllable capacitance unit, namely regulate and control the voltage at two ends of the controllable capacitance unit. According to the resonant circuit structure provided by the invention, the regulation and control of the voltage at two ends of the controllable capacitor unit is equivalent to the regulation and control of the output voltage. Therefore, the voltage gain of the high-frequency resonance inverter provided by the invention can be regulated. Note that the voltage gain is the ratio of the magnitude of the output voltage to the magnitude of the input voltage.

Referring to fig. 6, the controllable inductance unit includes a controllable inductance Ls and a first switching tube S connected in series₁A second switch tube S₂. First switch tube S₁A second switch tube S₂Are all reversely connected with a diode in parallel, and the first switch tube S₁A second switch tube S₂And connecting the two opposite ends. In particular, the second switch tube S₂Second terminal and first switch tube S₁Is connected, the first terminal of the controllable inductance Ls is used as the first terminal of the controllable inductance unit (denoted with reference sign a); first switch tube S₁Is connected to the second terminal of the controllable inductance Ls.A second switch tube S₂As a second terminal of the controllable inductance unit (denoted with reference B). First switch tube S₁Control terminal and second switch tube S₂The control terminals of the first and second switches are respectively connected with the controller so as to access the second control signal.

In a switching cycle, the controllable inductance unit provides three operating modes under the control of the second control signal, which is as follows:

working mode one, the first switch tube S₁Conducting the first switch tube S₁The anti-parallel diode is turned off, and the second switch tube S₂Off, the second switching tube S₂The anti-parallel diode is turned on and the equivalent circuit is as shown in fig. 7 (a). Current I_ABSequentially passes through a controllable inductor Ls and a switching tube S₁Switch tube S₂An anti-parallel diode. At this time, the equivalent inductance value of the controllable inductor Ls is the inductance value of the controllable inductor Ls itself.

Working mode two, the first switch tube S₁A second switch tube S₂And their anti-parallel diodes are all turned off, the controllable inductor Ls does not work, and the equivalent circuit is shown in fig. 7 (b). At this time, no current flows through the controllable inductance unit, and the equivalent inductance value of the controllable inductance Ls is infinite.

Working mode III, a first switch tube S₁Turn off, first switch tube S₁The anti-parallel diode is conducted, and the second switch tube S₂Conducting the second switch tube S₂The anti-parallel diode is turned off and the equivalent circuit is as shown in fig. 7 (c). Current I_BAPass through a switch tube S in sequence₂Switch tube S₁An anti-parallel diode and a controllable inductor Ls. At this time, the equivalent inductance value of the controllable inductor Ls is the inductance value of the controllable inductor Ls itself.

From the analysis of the above three working modes, the equivalent inductance values in the first and third modes are the inductance value of the controllable inductor itself, and the equivalent inductance value in the second mode is infinite. By controlling switch S₁And S₂On or off, the controllable inductance unit shown in fig. 6 works alternatively in a certain combination form under the three working modes, so as to obtain the required equivalentAn inductance value. The specific combination of the three modes depends on the specific modulation strategy used in the practical application, and will not be described here.

By combining the four operating modes of the controllable inductance unit in a certain order and controlling the switching tube S in each mode₁And S₂And the time of switching on or off regulates and controls the equivalent inductance value of the controllable inductance unit in a switching period, so that the impedance value of the controllable inductance unit is regulated and controlled, namely the voltage at two ends of the controllable inductance unit is regulated and controlled. According to the resonant circuit structure provided by the invention, the regulation and control of the voltage at two ends of the controllable inductance unit is equivalent to the regulation and control of the output voltage. Therefore, the voltage gain of the high-frequency resonance inverter provided by the invention can be regulated.

In conjunction with the above-described controllable capacitance unit and controllable inductance unit, the present invention provides the following embodiments to help further understand the high frequency resonant inverter provided by the present invention.