Power electronic transformer control method based on hybrid pulse width modulation (HPWM)

Abstract

The invention discloses a power electronic transformer control method based on hybrid pulse width modulation (HPWM). The method includes a CHB input-stage circuit control method and an IBDC output-stage circuit control method. According to the invention, HPWM is applied to cascaded power electronic transformers, and back-stage IBDC is used to control the intermediate DC voltage, an input-stage cascaded H-bridge rectifier only carries out simple power equalization, so as to simplify the control complexity. In order to solve the power equalization problem, the invention provides a switch-mode loop algorithm. With the algorithm, the opportunities of each module to participate in different switch modes are equal in the loop period, and the power is evenly distributed in a certain period of time; with the loop strategy, the HPWM modulation algorithm can be simplified, judging the current direction is not required, and the switch mode of each module can be determined only with the voltage instructions.

Description

technical field [0001] The invention relates to a power electronic transformer control method, in particular to a power electronic transformer control method based on hybrid pulse width modulation, and belongs to the technical field of power electronic transformer control. Background technique [0002] The cascaded power electronic transformer adopts a cascaded H-bridge (CascadedH-Bridge, CHB) plus an isolated bidirectional DC / DC converter (isolated bidirectional DC / DC converter, IBDC) topology, which can use low withstand voltage devices to achieve high-voltage multi-level output, with a waveform With the advantages of good quality, few required components, simple PWM control, and easy modular expansion, it is an important device in the application fields of "smart grid" and "energy Internet". [0003] Multi-level modulation technology is the key technology of the input stage rectifier of the cascaded power electronic transformer. In the traditional carrier phase-shift meth...

AI Technical Summary

Problems solved by technology

However, when HPWM is directly applied to power electronic transformers, the difference in switching modes will cause the power imbalance of each module, which not only causes problems such as increased intermediate DC voltage differences and serious output waveform distortion, but also affects the voltage of each power unit of the power electronic transformer. , current stress, heat dissipation, and life will all cause adverse effects, which must be addressed in the control strategy

Existing HPWM applications are mainly aimed at cascaded H-bridge rectifiers. The specific implementation is to determine the switching mode of each H-bridge through the method of voltage sequencing, which can realize the balance of the DC voltage of each H-bridge, but does not involve the power balance of each H-bridge, and The voltage sorting method takes up a lot of resources, and the switching mode of each module needs to be determined according to the voltage command and current direction, and the control logic is more complicated

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