The Study Of Switching Power Amplifier Based On An Improved One-Cycle Control

Power amplifier is widely used in industry, aviation electronics, communication system, home entertainment and etc. Switching power amplifier has advantages over volume, efficiency and power dissipation because of its high efficiency. People pay more and more attention to switching power amplifier now, which has become the hotspot in power electronics field.The distortion introduced by switching power amplifier is typically larger than in their liner counterparts due to intrinsic nonlinearity of switching converter. One of the key factors of affecting fidelity of switching power amplifier is control technique. One-cycle control theory developed in 1990s is a large signal nonlinear PWM control to make the average of the controlled switch-variable to be equal to or proportional to the control reference in each switching cycle.In this thesis, switching power amplifier based on one-cycle control is analyzed in detail, simulation and experiment works are performed.The basic structure and operational principle of the buck circuit by using classical and improved one-cycle control with single-edge modulation are analyzed and compared through simulation. The simulation results show that the latter has more constant switching frequency and lower total harmonic distortion.The basic structure and operational principle of the buck circuit by using classical and improved one-cycle control with double-edge modulation are analyzed and control equations are deduced. The small switching frequency variation of the single-edge and double-edge modulation due to changes in reference signal and supply voltage are quantified, Using double-edge modulation, the switching frequency variation is further reduced, thus, the associated signal distortion is minimized.The basic structure and operational principle of the full bridge circuit based improved one cycle control with double-edge modulation are analyzed and control equations are deduced. Small signal model is established. DC offset voltage of switching power amplifier based on one-cycle control is analyzed, a voltage compensation technique is used to solve this question, and the computation formula of compensation voltage is given. The circuit compensations are studied through simulation, the simulation results show that circuit compensation solve the output DC offset effectively.