CN-114785177-B - High-frequency chain single-stage soft switching DC-AC converter and control method thereof

Abstract

The invention discloses a high-frequency chain single-stage soft switching DC-AC converter and a control method thereof, wherein the high-frequency chain single-stage soft switching DC-AC converter comprises a direct current input power supply, a primary side inverter circuit, a resonant cavity, a high-frequency transformer, a frequency converter, a filter, a load and a controller; the DC input power supply is connected with the load through the primary side inverter circuit, the resonant cavity, the high-frequency transformer, the frequency converter and the filter in sequence, and the controller is connected with the load, the primary side inverter circuit and the frequency converter.

Inventors

• ZHOU XIANG
• WANG LAILI

Assignees

• 西安交通大学

Dates

Publication Date

20260512

Application Date

20220516

Claims (7)

1. 1. The high-frequency chain single-stage soft switching DC-AC converter is characterized by comprising a direct-current input power supply (1), a primary side inverter circuit (2), a resonant cavity (3), a high-frequency transformer (4), a frequency converter (5), a filter (6), a load (7) and a controller (8); The direct current input power supply (1) is connected with a load (7) through a primary side inverter circuit (2), a resonant cavity (3), a high-frequency transformer (4), a frequency converter (5) and a filter (6) in sequence, and a controller (8) is connected with the load (7), the primary side inverter circuit (2) and the frequency converter (5); The primary inverter circuit (2) comprises a primary first switching tube, a primary second switching tube, a primary third switching tube and a primary fourth switching tube, wherein the positive electrode of the direct current input power supply (1) is connected with one end of the primary first switching tube and one end of the primary third switching tube, the negative electrode of the direct current input power supply (1) is connected with one end of the primary second switching tube and one end of the primary fourth switching tube, the other end of the primary first switching tube is connected with the other end of the primary second switching tube and one end of the input end of the resonant cavity (3), and the other end of the primary third switching tube is connected with the other end of the primary fourth switching tube and the other end of the input end of the resonant cavity (3); the frequency converter (5) comprises a first inductor, a second inductor, a first bidirectional switching tube, a second bidirectional switching tube, a third bidirectional switching tube and a fourth bidirectional switching tube; One end of a secondary side in the high-frequency transformer (4) is connected with one end of a first inductor, the other end of the secondary side in the high-frequency transformer (4) is connected with one end of a second inductor, the other end of the first inductor is connected with one end of a first bidirectional switch tube and one end of a second bidirectional switch tube, the other end of the second inductor is connected with one end of a third bidirectional switch tube and one end of a fourth bidirectional switch tube, and the other end of the first bidirectional switch tube, the other end of the second bidirectional switch tube, the other end of the third bidirectional switch tube and the other end of the fourth bidirectional switch tube are connected with the input end of a filter (6).
2. 2. The high frequency link single stage soft switching DC-AC converter of claim 1, wherein the first bi-directional switching tube is comprised of a secondary side first switching tube and a secondary side first diode.
3. 3. The high frequency link single stage soft switching DC-AC converter of claim 2, wherein the second bi-directional switching tube is comprised of a secondary side second switching tube and a secondary side second diode.
4. 4. A high frequency link single stage soft switching DC-AC converter according to claim 3, characterized in that the third bi-directional switching tube is composed of a secondary side third switching tube and a secondary side third diode.
5. 5. The high frequency link single stage soft switching DC-AC converter of claim 4, wherein the fourth bi-directional switching tube is comprised of a secondary side fourth switching tube and a secondary side fourth diode.
6. 6. The high frequency link single stage soft switching DC-AC converter of claim 5, wherein the secondary side first switching tube, the secondary side second switching tube, the secondary side third switching tube, and the secondary side fourth switching tube are wide bandgap semiconductor devices.
7. 7. The control method of the high-frequency chain single-stage soft switching DC-AC converter is characterized in that a controller (8) collects voltage signals at two ends of a load (7) as feedback signals, and adopts pulse density control, pulse skipping period modulation and pulse frequency modulation control strategies to control the frequency and pulse width of a primary first switching tube, a primary second switching tube, a primary third switching tube and a primary fourth switching tube in a primary inverter circuit (2) and a secondary first switching tube, a secondary second switching tube, a secondary third switching tube and a secondary fourth switching tube in a frequency converter (5) so that the switching frequency is always lower than the series resonance frequency and works in an inductive area of a resonant cavity (3).

Description

High-frequency chain single-stage soft switching DC-AC converter and control method thereof Technical Field The invention belongs to the technical field of power electronic converters, and relates to a high-frequency chain single-stage soft switching DC-AC converter and a control method thereof. Background In many special inverter applications related to national life, complex waveforms with extremely wide ranges of amplitude and frequency variation are generally output. For example, a DC-AC converter in an underwater vehicle sonar system needs to generate a sine wave of several Hz to hundreds of kHz to drive a wideband underwater acoustic transducer to fully detect the seabed. In lithography machines, electroplating, micro-arc oxidation, induction heating, and laser transmitters, it is necessary to generate various complex high frequency pulses or gradient waveforms. In nuclear magnetic resonance and ultrasonic imaging apparatuses, waveforms having extremely large amplitude and frequency changes need to be generated by a DC-AC converter. Unlike conventional parallel/off-grid inverters with fixed frequency, phase and amplitude, in the above applications, the waveform on the AC side of the DC-AC converter output by arbitrary waveform has a common characteristic, that is, the frequency and amplitude have extremely wide variation ranges, so it is difficult to accurately detect the zero crossing point of the AC signal output by high frequency. The traditional isolated parallel/off-grid inverter mostly adopts a structure of a front-stage isolated DC-DC converter and a rear-stage inverter, and soft switching is realized by accurately detecting output zero crossing points and adopting different control time sequences in positive and negative half periods. However, in any waveform output DC-AC converter, positive and negative half waves cannot be accurately distinguished and output, so that full-range soft switching of all high-frequency switching tubes is difficult to realize, and improvement of the characteristics of converter efficiency, switching frequency and the like is limited. Although some high frequency chain DC-AC converters achieve single stage power conversion by adding complex auxiliary circuits, soft switching of all switching tubes is still not possible. Therefore, in the application of the random waveform output DC-AC converter which is difficult to detect the output zero crossing point, the soft switching of the high-frequency switching tube is realized by a method without the output zero crossing detection under the condition of no additional auxiliary circuit, and the method becomes the current research difficulty and key point. Disclosure of Invention The invention aims to overcome the defects of the prior art and provide a high-frequency chain single-stage soft switching DC-AC converter and a control method thereof, wherein the method can realize the soft switching of a high-frequency switching tube by a zero crossing detection method without an additional auxiliary circuit. In order to achieve the purpose, the high-frequency chain single-stage soft switching DC-AC converter comprises a direct current input power supply, a primary side inverter circuit, a resonant cavity, a high-frequency transformer, a frequency converter, a filter, a load and a controller; the DC input power supply is connected with the load through the primary side inverter circuit, the resonant cavity, the high-frequency transformer, the frequency converter and the filter in sequence, and the controller is connected with the load, the primary side inverter circuit and the frequency converter. The primary inverter circuit comprises a primary first switching tube, a primary second switching tube, a primary third switching tube and a primary fourth switching tube, wherein the positive electrode of a direct current input power supply is connected with one end of the primary first switching tube and one end of the primary third switching tube, the negative electrode of the direct current input power supply is connected with one end of the primary second switching tube and one end of the primary fourth switching tube, the other end of the primary first switching tube is connected with the other end of the primary second switching tube and one end of the resonant cavity input end, and the other end of the primary third switching tube is connected with the other end of the primary fourth switching tube and the other end of the resonant cavity input end; the frequency converter comprises a first inductor, a second inductor, a first bidirectional switching tube, a second bidirectional switching tube, a third bidirectional switching tube and a fourth bidirectional switching tube; One end of a secondary side in the high-frequency transformer is connected with one end of a first inductor, the other end of the secondary side in the high-frequency transformer is connected with one end of a second inductor, the other end of the first indu