Large capacity cascade multi-phase multi-level power converter without transformer

Abstract

The present invention discloses a large-capacity cascades multiphase multi- electrical level power converter without transformer, which belongs to high pressure large-capacity multiphase multi- electrical level frequency conversion technology field, and characterized in that a single-phase main circuit is composed by identical prime power convert unit through cascades; three single-phase main circuits are connected to the three phase electric network through star or triangle shape; the prime power convert unit constitutes 'back to back' AC-DC-AC inverter circuit topology through DC bus capacitance with multiphase inverter by H-type rectifying bridge; different electrical level, types, number of phases and connecting relation of the prime power convert unit can extends various different polyphase converter practical topology circuit, which saves phase-shifting transformer that original absolutely necessarily but volume weight covers more than one third of that of system, which reduces greatly volume and cost of complete appliance. The present invention is capable of realize high performance operation of speed governing system in four quadrant scope, can feedback energy from the electric motor to the electric network when the electric motor brakes, enhances working condition operation efficiency of speed governing system; and communicate electric network side current harmonics small and power factor close to 1.

Description

technical field [0001] The invention relates to a high-voltage, large-capacity, multi-phase and multi-level topological structure of power electronics, in particular to a cascaded back-to-back double PWM controlled power converter topology. Background technique [0002] Frequency conversion speed regulation technology has been widely used in high-voltage and large-capacity speed regulation fields such as building materials, metallurgy, ships, locomotive traction, and cement due to its energy-saving advantages. With the advancement of power electronic devices, topologies and related control technologies, large electric drive systems are developing towards the direction of large single-unit capacity and high power density. However, limited by the withstand voltage level and current-carrying capacity of existing power devices, the conversion device of the traditional two-level three-phase inverter is difficult to meet the high-voltage and high-power power conversion requirement...

AI Technical Summary

Problems solved by technology

However, the improvement of the circuit still requires a phase-shifting transformer, and the disadvantages of large volume, weight, and high cost have not changed.

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