Rectifier soft start circuit and control method thereof

Abstract

The invention provides a rectifier soft start circuit and a control method thereof. The circuit is arranged between the rectifier and a load, and comprises a first capacitor, a current-limiting unit, a relay and a DSP processor; one end of the current-limiting unit, one end of the relay, one end of the load and the positive DC bus of the rectifier are connected together; the other end of the load, the cathode of the first capacitor and the negative DC bus of the rectifier are connected together; the anode of the first capacitor, the other end of the current-limiting unit and the other end of the relay are connected together; and the DSP processor is used for controlling on and off of the relay. When the current-limiting unit is an IGBT transistor, the control method comprises steps: the DSP processor controls on and off of the IGBT transistor, charging and discharging of the first capacitor are thus controlled, the first capacitor is directly parallelly connected with the load, and thus start of the rectifier circuit is completed. By adopting the technical scheme of the invention, impact current in the case of start can be eliminated, and the start is quick.

Description

technical field [0001] The invention relates to rectifier technology, in particular to a rectifier soft-start circuit and a control method, which belong to the field of power electronic AC technology. 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 current during start. The current soft start circuit usually connect...

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 during start. 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 this technology is that the starting time is long, especially for high-power three For a phase-voltage PWM rectifier, the start-up time will be more than 10s. At the same time, there will still be a large inrush current after the soft-start is completed, and the soft-start circuit can only be started under no-load conditions, and soft-start cannot be achieved when there is a load.

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