A Novel Control Method Of Switching Power Amplifier

Power amplifier is the equipment that amplifying the input signal into the needed signal. The requirements are: the change of output signal is consistent with input signal, namely, low distortion; and the loss of the power amplifier is low, namely, high efficiency.Conventional power amplifiers amplified analog signals directly, and the switches must work in linear area. So the conventional power amplifier has low distortion and large loss.The power amplifier is worked in PWM mode. The input signal is compared with carrier wave signal, then the PWM signal is got, whose pulse width is in proportion with the amplitude of the input signal. Thus the power switch is driven through drive circuit. The function is achieved by controlling the power switches. The amplified PWM voltage is reverted into amplified input signal through low-pass filter. The power switches of switching power amplifier work in on & off state, so the efficiency can achieve 100% theorily, and more than 80% in practice. The efficiency of switching power amplifiers is high, that have advantages in the situations with high demands in cubage, efficiency, and loss. At present, switching power amplifier becomes the research focus of power electrics field.The switching power amplifier has the advantage of high efficiency, but due to the nonlinear character, the distortion of switching power amplifier is more than the conventional linear amplifier. That is the reason that the switching power amplifier is difficult to become popular. The control method is the critical technique of switching power amplifier, which directly effects the distortion. The available control methods can improve the distortion in some extent, but the precondition is increasing the switching loss.This dissertation was based on switching power amplifier, analyzed the reasons that cause the output distortion of the switching power amplifier, and presented a novel control method of switching power amplifier. This control method separated the power circuit and compensation circuit, solved the conflict between the efficiency and distortion of switching power amplifier. The simulation and experiment results were proved the validity. The main achievements are:1. Introducing the principle and configuration of the switching power amplifier...