Power electronic transformer circuit, power electronic transformer and control method

Abstract

The invention discloses a power electronic transformer circuit, a power electronic transformer and a control method of the power electronic transformer; a multi-winding transformer is arranged among acascade H bridge and an inversion H bridge connected with a three-phase alternating current power grid, and a rectifying H bridge arranged at the input end of a direct current power grid; the input end of the multi-winding transformer is connected with H bridge modules connected from a three-phase alternating-current power grid; the input power of each H bridge module comprises a direct-current component and a secondary pulsation component, and the secondary pulsation power is in a rule of three-phase symmetry and negative sequence; after the multi-winding transformer is input from the threeH bridge modules, the output power of the multi-winding transformer is equal to the synthesis of input power of three ports according to the power balance relation, the secondary pulsation power is counteracted, and only the direct current component is transmitted to the direct current output end. A direct-current capacitor in the cascaded H bridge does not need to store pulse power, and the volume of the direct-current capacitor can be remarkably reduced, so that the size of the power electronic transformer is reduced, and the voltage and current stress of the power device is reduced.

Description

technical field [0001] The invention relates to the technical field of power electronics, in particular to a power electronic transformer circuit, a power electronic transformer and a control method for the power electronic transformer. Background technique [0002] Compared with the traditional line frequency transformer (Line Frequency Transformer, LFT), the power electronic transformer (power electronics transformer, PET) can not only significantly reduce the volume and weight of the transformer and passive filter components in the system, but also realize reactive power compensation, harmonic Wave compensation, power flow control, redundant backup, power system failure protection and other functions are one of the key technologies in the development of smart grid. Power electronic transformers are not only suitable for traditional AC / AC power conversion, but also for AC / DC grid interconnection. In high-voltage, high-power AC / DC applications, power electronic transformer...

AI Technical Summary

Problems solved by technology

[0008] To sum up, in the power electronic transformer circuit in the prior art, due to the pulsating power introduced by the AC input, a larger capacitor has to be used to store the pulsating power to prevent the pulsating power from damaging the circuit, thereby increasing the overall power electronic capacity. The size of the transformer is not conducive to the simplification of the system, which is not conducive to the long-term development

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