Soft switching three-phase gird-connected inverter additionally provided with freewheeling path

Abstract

The invention discloses a soft switching three-phase gird-connected inverter additionally provided with a freewheeling path, which comprises an inverter direct current power supply, a three-phase bridge arm formed by six full-control master switches with antiparallel diodes, and output filter inductors respectively connected between the midpoint of each phase of the bridge arm and an alternating current grid, wherein the three-phase bridge arm is connected with a full-control switch with an antiparallel diode, the full-control switch and the six master switches of the three-phase bridge arm are respectively connected with a capacitor in parallel, an auxiliary switch with an antiparallel diode and a serial branch of a clamp capacitor are accessed between the inverter direct current power supply and a direct current bus of the three-phase bridge arm, and a resonance inductor Lr is bridged at two ends of the serial branch, and the auxiliary switch is connected in parallel with the capacitor. The invention is simple in structure, can suppress the reverse recovery of the diodes, and reduces the electromagnetic interference. All switches of the inverter realize zero-voltage switching-on, thus the inverter has the advantages of little switching loss and high circuit efficiency. The inverter can realize control of power factors and harmonic waves for output grid-connected current, and can be used in a grid-connected inverter in various power supplies.

Description

technical field [0001] The invention relates to an inverter, especially a soft-switching three-phase grid-connected inverter with an additional freewheeling path. Background technique [0002] A three-phase inverter with grid-connected power generation function, its circuit is as follows figure 1 As shown, it consists of six fully controlled main switches S with anti-parallel diodes 1 ~S 6 The three-phase bridge arms formed are respectively connected to the output filter inductance L between the midpoint of each phase bridge arm and the AC grid a ~ L c . This kind of three-phase inverter can realize the function of grid-connected power generation, but the circuit works in a hard switching state, there is a reverse recovery problem of the diode, and the switching loss of the device is large, which limits the improvement of the operating frequency, reduces the circuit efficiency and has relatively large large electromagnetic interference. Contents of the invention [0...

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Problems solved by technology

This kind of three-phase inverter can realize the function of grid-connected power generation, but the circuit works in a hard switching state, there is a problem of reverse recovery of the diode, and the switching loss of the device is large, which limits the increase of the operating frequency, reduces the circuit efficiency and has relatively large large electromagnetic interference

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