An afe active front-end pwm rectification method

Abstract

The invention belongs to the technical field of power equipment, and specifically relates to an AFE (Active Front End) PWM (Pulse Width Modulation) rectification method. The method comprises a pre-charging circuit, an input-side filtering unit, a rectification module and an inverter unit which are sequentially connected between a power grid and a load, and is characterized in that a compensation filtering module used for outputting pure compensation energy into the input-side filtering unit is connected between the pre-charging circuit and the input-side filtering unit, the output end of the rectification module is connected with an output-side filtering unit, the output-side filtering unit is connected in the power grid; and the output end of the rectification circuit is provided with anoutput-side filtering unit. Meanwhile, a compensation filtering module is arranged between the pre-charging circuit and the output-side filtering unit, the energy output by the load side is compensated by using the stored energy in the pre-charging circuit if the energy feedback at the load side causes a great waveform change so as to perform waveform rectification, so that the quality of the voltage input into the power grid can be effectively improved.

Description

technical field [0001] The invention belongs to the technical field of power equipment, and in particular relates to an AFE active front-end PWM rectification method. Background technique [0002] Ordinary AC-DC-AC VFD front-end usually adopts fixed three-phase bridge diode rectification method to convert the three-phase AC power provided by the grid into DC power, and the DC power is supplied after being smoothed and filtered by a large-capacity electrolytic capacitor The three-phase bridge inverter composed of IGBT is converted into an AC voltage with synchronous regulation of frequency and voltage, and drives the motor to run at different frequencies. Since the front end of the ordinary inverter adopts diode bridge rectification, the energy can only flow from the power grid to the inverter DC bus, and the bidirectional flow of energy cannot be realized. At the same time, due to the limitation of the diode full-bridge rectification, the grid-side power factor of the invert...

AI Technical Summary

Problems solved by technology

[0003] In elevators, hoists, cranes, and motor drive systems for various inertial loads, since the motor windings are rotating, they can reversely generate energy to the grid. When the number of motor windings is large, the grid voltage will fluctuate and affect DC. The stability of the bus voltage requires the configuration of corresponding multi-winding transformers for balance, which increases equipment costs

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