This paper introduces a voltage source PWM rectifer based on invariable switch frequency variable structure control

which not only outputs steady volts d.c. in spite of the change of load

but compensates reactive current and harmonic current. The paper presents the principle of one-phase bridge rectifier circle based on Invariable Switch Frequency Variable Structure Control and the results of simulation analysis verify the viability of the method. Keywrod: voltage source PWM rectifer;invariable switch frequency;variable structure control