Current-mode Pwm Rectifier And Applied Research, Induction Heating

Current-source PWM rectifier is considered as a "green" electrical energy converter with a lot of merit. Harmonic content of input current on line side is very few, it can achieve unity power factor or make power factor be changed. It can vary output power, and the DC output voltage is below source voltage. It can realize four-quadrant run and allow bi-directional power flow. Besides these, it has good capability of over-current protection, the reliability of short protection is high. In this paper, current-source PWM rectifier and its application in the induction heating have been deeply studied in theory and practice.In the beginning, the mathematical model of three-phase current-source PWM rectifiers have been founded in three-phase stationary coordinate from low frequency and high frequency. They establish theoretical foundation for the deeper research on three-phase current-source PWM rectifiers. The dissertation analyzes SPWM modulation strategy of three-phase current-source PWM rectifiers, it introduces tri-logical switch function of current-source PWM rectifier that comes from bi-logical signal of voltage-source PWM rectifier. It researches the tri-logical signal's generation and the switches' operating mode of three-phase current-source PWM rectifier, and it decides the zero-state selection from switching combination according to the minimum switch rule. This paper also researches the control strategy, it introduces the direct current control method of three-phase current-source PWM rectifier. After the static characteristics of three-phase current-source PWM rectifier were studied, the paper gives research on the theory and method of indirect current control particularly and introduces the feasibility and conditions of unity power factor control on line side. On the basis of above theory analysis, it construct a induction heating system build on three-phase current-source PWM rectifier. It carries through simulation and experimental research. It also gives out the design of main circuit and its control system. It presents tri-logical SPWM digital implement technique of three-phase current-source PWM rectifier. The simulation and experimental result all validate this method can not only make output power variable but also achieve unity power factor. At last, comparing to traditional induction heating technique, it analyzes the merits and demerits of this method. It verifies the feasibility and practicality of this induction heating technique build on three-phase current-source PWM rectifier.