Neutral point clamped inverter for three-phase three-level diode of zero voltage switch and modulation method for neutral point clamped inverter

Abstract

The invention discloses a neutral point clamped inverter topology for a three-phase three-level diode of a zero voltage switch and a modulation method for a neutral point clamped inverter. The topology comprises a three-phase bridge arm consisting of 12 main switches connected in antiparallel with diodes and 6 diodes, an output inductor connected between the output neutral point of the bridge arm and a load, and positive and negative bus capacitors connected between the positive end and the negative end of a direct current bus, and is characterized in that the main switches of the bridge arm is connected in parallel with a capacitor; resonant inductors are respectively connected between the positive input end of the bridge arm and the positive electrode of the positive bus capacitor as well as between the negative input end of the bridge arm and the negative electrode of the negative bus capacitor; the two ends of the resonant inductors are bridged with a circuit formed by connecting auxiliary switches with antiparallel diodes with a clamped capacitor in series; the two ends of the auxiliary switches are connected in parallel with a capacitor; short-circuit switches are respectively connected between the positive input end of the bridge arm and the negative electrode of the positive bus capacitor as well as between the negative input end of the bridge arm and the positive electrode of the negative bus capacitor. The modulation method is generating auxiliary switch and short circuit switch signals according to a main switch driving signal timing sequence of the three-phase bridge arm, so that zero voltage on and off of all the switch devices can be realized.

Description

technical field [0001] The invention relates to a three-phase three-level inverter, in particular to a topology of a zero-voltage switch three-phase three-level diode mid-point clamp inverter and a modulation method thereof. Background technique [0002] The inverter is a device that converts direct current into alternating current. A common topology such as a three-phase three-level diode mid-point clamp inverter consists of twelve fully-controlled main switches (S a1 ~S a4 ,S b1 ~S b4 ,S c1 ~S c4 ) and six clamping diodes (D ap ,D an ,D bp ,D bn ,D cp ,D cn ) composed of three-phase bridge arms, respectively connected to the output inductance between the output midpoint of each phase bridge arm and the load (L a , L b , L c ), two DC bus capacitors (C 1 ,C 2 ). The circuit works in a hard switching state, and there is a diode reverse recovery phenomenon. During this period, the switching loss is large, which limits the improvement of the operating frequency...

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Problems solved by technology

The circuit works in a hard switching state, and there is a diode reverse recovery phenomenon. During this period, the switching loss is large, which limits the improvement of the operating frequency, resulting in the need to use a larger filter, which reduces the circuit efficiency and has electromagnetic interference.

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