Multi-level inverter circuit and system based on switched capacitor and diode clamping

Abstract

The invention provides a multi-level inverter circuit based on a switched capacitor and a diode clamp. The multi-level inverter circuit solves the problems that when an existing multi-level inverter circuit directly expands the number of switching tubes to achieve multi-level output, circuit loss and investment cost are increased. According to the invention, only a small number of devices are added, and on-off of a full-control switch tube in a half-bridge inversion module is matched, so that multi-level state output is realized, excessive expansion of the switch tube is avoided, the switch loss of the whole circuit is reduced, and the investment cost is reduced.

Description

technical field [0001] The present invention relates to the technical field of multilevel inverters, and more specifically, to a multilevel inverter circuit and system based on switched capacitors and diode clamps. Background technique [0002] Because the multi-level inverter circuit has many advantages such as low output voltage harmonic content and low device voltage capability, it is widely used in high-power electric drive, high-voltage AC-DC transmission and new energy grid-connected applications. [0003] Traditional typical diode-clamped three-level inverter circuit such as figure 1 As shown, the circuit consists of four fully controlled switches S 1 ~S 4 and 2 diodes D 1 ~D 2 , Capacitor C 1 and capacitor C 2 form, capacitor C 1 and capacitor C 2 is the input voltage divider capacitor, normally, the capacitor C 1 and capacitor C 2 Each bears the voltage of +2E, and the connection point a2 is the neutral point of the three-level inverter circuit. By control...

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Problems solved by technology

[0003] Traditional typical diode-clamped three-level inverter circuit such as figure 1 As shown, the circuit consists of four fully controlled switches S 1 ~S 4 and 2 diodes D 1 ~D 2 , Capacitor C 1 and capacitor C 2 form, capacitor C 1 and capacitor C 2 It is the input voltage dividing capacitor. Normally, the capacitor C 1 and capacitor C 2 Each bears the voltage of +2E, and the connection point a2 is the neutral point of the three-level inverter circuit. By controlling the orderly on-off of the four full-control switches, the circuit can convert the DC power supply voltage 4E into a voltage containing 0 and ± 2E three-level alternating current output. In addition, the Chinese patent with the publication number CN110707955A and the publication date of January 7, 2020 also discloses a three-phase multi-level inverter circuit, which can be powered by only one power input. The realization of three-phase multi-level AC output solves the problem that the existing multi-level inverter circuit needs multiple input power sources to achieve three-level output, but further, when the number of output levels is actually required to be large, the existing The multi-level inverter circuit needs to expand more switch tubes to achieve multi-level output, and the increase in the number of switch tubes also increases the loss of the entire circuit

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