Three-level half-bridge soft switching converter circuit, control system and control method thereof

Abstract

The invention provides a three-level half-bridge soft switching converter circuit, a control system and a control method thereof. The three-level half-bridge soft switching converter circuit comprises a first input capacitor bank, a second input capacitor bank and a three-level half-bridge inverter circuit which are connected in parallel, and a first inductor, a blocking capacitor, a transformer and an output circuit. After the first inductor, the blocking capacitor and the primary side of the transformer are connected in series, one ends of the first inductor, the blocking capacitor and the primary side of the transformer are connected with the midpoint of a bridge arm of the three-level half-bridge inverter circuit, the other ends of the first inductor, the blocking capacitor and the primary side of the transformer are connected with the midpoint of the first input capacitor bank, the clamping diode connecting midpoint of the three-level half-bridge inverter circuit is connected with the midpoint of the second input capacitor bank, and the secondary side of the transformer is connected with the output circuit. Each switching tube can be in a soft switching state when being turned on and turned off. Mid-point potential balance of the input capacitor is realized.

Description

technical field [0001] The disclosure belongs to the technical field of DC-AC-DC converter circuits, and in particular relates to a three-level half-bridge soft-switch converter circuit and a control method thereof. Background technique [0002] The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art. [0003] The traditional two-level converter circuit has the advantages of simple topology and easy control, and is widely used in various DC-AC-DC converter circuits. However, the two-level converter circuit also has problems such as high requirements for the withstand voltage of the switching tube, large switching stress, and difficulty in increasing the frequency, which are greatly restricted in high-voltage input applications. The three-level half-bridge inverter circuit has half the withstand voltage of the switch tube as that of the two-level inverter circuit, the switch stress is ...

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Problems solved by technology

[0004] In the prior art, although there is a topology in which the converter circuit adopts soft switching, each switching tube is hard-off when it is turned off, and can only achieve zero-voltage conduction, and the soft-switching effect is poor, or a passive auxiliary network is used. Realize the zero-voltage switch of the three-level half-bridge circuit, but the auxiliary network increases the complexity and cost of the system, or uses the auxiliary hardware circuit to realize the potential balance of the midpoint of the input capacitor, but the circuit is more complicated, which reduces the reliability of the system, or through the detection The capacitor voltage corrects the modulation wave to achieve the potential balance of the midpoint of the input capacitor, but it needs to increase the voltage detection circuit, and the control algorithm is also more complicated

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