Синтез системы управления безмостовым корректором коэффициента мощности в режиме прерывистого тока

Abstract

The classical systems for control of power factor correctors (PFC) are subordinated-type control systems with two feedback loops: a slow loop serving to stabilize the output voltage and a fast loop serving to shape a sinusoidal input current. Designing of these control systems involves difficulties due to the need of ensuring stable operation of the external and internal loops in the specified range of input voltage and output power. The power factor correction converters with linear input volt-ampere and adjustment characteristics do not require the current loop because the input current will repeat the network voltage waveform due to the power circuit features. The specific features of synthesizing a single-loop control system for a power factor corrector that uses a bridgeless single-phase PFC as the power circuit. Such a structure operating in the choke discontinuous conduction mode has the property of self-correcting the power factor and can operate at a network voltage either higher or lower than the input voltage. The use of a boost and buck-boost PFC makes it possible to do without a secondary DC-DC converter serving to match the boost PFC with the load. The adjustment characteristics of a bridgeless PFC operating in discontinuous and continuous conduction modes are presented. The converter nonlinear model linearized using the Matlab/Simulink tools and a manually linearized model in the form of a control transfer function are constructed. It is shown that with the bridgeless PFC operating in the intermittent current mode, the frequencies of right-half plane zeroes and high- frequency poles are located much higher than the frequency of the voltage loop unity gain and do not affect the stability of converter operation. The switched model involving a correction loop synthesized in the Matlab/Simulink environment was investigated, and it has been demonstrated that the converter shows stable operation in the entire range of input voltage and output power. Hence, it can be stated that the used continuous and single-loop control system can be used for inverting, series-parallel, flyback, and other converters operating in the intermittent current mode and having the power factor self-correction ability.