Voltage equalizing circuit, flying capacitor three-level converter and equipment

Abstract

The invention provides a voltage equalizing circuit, a flying capacitor three-level converter and equipment, wherein the first switching tube, the second switching tube, the third switching tube and the fourth switching tube in the flying capacitor three-level converter are connected in series in sequence ; The first switch tube and the fourth switch tube are connected to the high-voltage port; the third switch tube and the fourth switch tube are connected to the low-voltage port; the flying capacitor is connected in parallel to the first end of the second switch tube and the second end of the third switch tube between the terminals; and the equalizing circuit includes: a first equalizing element, a second equalizing element, a third equalizing element, and a first equalizing branch, wherein the first equalizing element is connected in parallel to the two ends of the first switching tube terminal; the second equalizing element is connected in parallel between the first end of the second switching tube and the second end of the third switching tube; the third equalizing element is connected in parallel at both ends of the fourth switching tube; the first equalizing branch It is connected in parallel to the two ends of the third switching tube, thereby reducing the possibility of overvoltage of the flying capacitor, improving the voltage balance when the circuit is started, and accelerating the dynamic response.

Description

technical field [0001] The invention relates to the field of circuit technology, in particular to a voltage equalizing circuit, a flying capacitor three-level converter and equipment. Background technique [0002] Non-isolated DC converters are widely used in rail transit, electric power, new energy power generation, energy storage, high-power transmission and other fields. However, the flying capacitor three-level converter is more likely to be commercialized due to its advantages of less components, flexible control, and high efficiency. In these devices using flying capacitor three-level converters, flying capacitor three-level converters need to be switched on and off frequently, and each time the flying capacitor three-level converter is shut down, the circuit breaker needs to be turned off. When starting up again, it is necessary to establish the voltage of the flying capacitor first, and then close the corresponding circuit breaker. The opening process usually takes ...

AI Technical Summary

Problems solved by technology

[0004] However, in standby mode, the flying capacitor voltage is no longer determined by the high-voltage side voltage, but is generated by the joint excitation of the high-voltage side voltage and the low-voltage side voltage. The existing flying capacitor three-level converter may have a flying capacitor voltage The problem of unbalance may cause overvoltage of the flying capacitor, and the reliability is not high enough

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