Quick soft start circuit for three-phase voltage PWM rectifier and control method thereof

Abstract

The invention discloses a quick soft start circuit for a three-phase voltage PWM rectifier and a control method of the quick soft start circuit. The quick soft start circuit comprises a first small capacitor, a second large capacitor, a seventh switching tube and a DSP. The anode of the first small capacitor, the output end of the positive electrode of a three-phase rectifier bridge and the collector electrode of the seventh switching tube are connected together. The cathode of the first small capacitor, the output end of the negative electrode of the three-phase rectifier bridge, the cathode of the second large capacitor and one end of a load are connected together. The emitting electrode of the seventh switching tube, the anode of the second large capacitor and the other end of the load are connected together. The DSP controls the on-off state of the seventh switching tube through a signal output by an IO port. The quick soft start circuit for the three-phase voltage PWM rectifier achieves soft start by charging the second large capacitor in a time-sharing mode. Besides, the start speed is high, the circuit is not provided with a current-limiting resistor, and therefore loss is small in the starting process.

Description

technical field [0001] The invention relates to a three-phase rectification technology, in particular to a fast soft-start circuit and a control method for a three-phase voltage-type PWM rectifier, and belongs to the technical field of power electronic communication. Background technique [0002] The three-phase voltage-type PWM rectifier has many advantages such as unity power factor, low current harmonics, bidirectional flow of energy, etc., and has become one of the hot topics in the field of power electronics. The soft start technology of the three-phase voltage PWM rectifier is one of the key technologies for the application of the three-phase voltage PWM rectifier. Due to the large capacitance on the DC side, a large inrush current will be generated at the moment the circuit is started, which not only affects the life of the components in the circuit, but also has a great impact on the power grid. The main purpose of the soft-start technology is to reduce the inrush c...

AI Technical Summary

Problems solved by technology

Due to the large capacitance on the DC side, a large inrush current will be generated at the moment the circuit starts, which not only affects the life of the components in the circuit, but also has a great impact on the power grid.

The main purpose of the soft-start technology is to reduce the inrush current when starting. The current soft-start circuit usually connects the current-limiting resistor in parallel with the switch tube or the current-limiting resistor in parallel with the relay. The disadvantage of the modified technology is that the startup time is long, especially for high-power For phase-voltage PWM rectifiers, the start-up time will be more than 10s, and at the same time, there will still be a large inrush current after the soft-start is completed, and the loss of the current-limiting resistor during the start-up of the soft-start circuit is relatively large

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