| Power amplifier have extensive application in industry, aviation electronics, communications,home entertainment and etc. .Switching power amplifier has advantage over volume,efficiency and power dissipation because of its high efficiency. The usage of digital signal and its merit in storage, transmission, and processing make people pursue to convert digital signal into PWM signal directly,which amplified through switching amplifier. People pay more and more attention to switching power amplifier, which became the hotspot in power electronics field.The distortion introduced by switching power amplifier is typically larger than in their linear counterparts due to intrinsic nonlineariry of switching converter.One of the key factors of affecting fidelity of switching power amplifier is control technique.One cycle control theory developed since 1990s is a large signal nonlinear PWM technology,which basic concept is to force the average of the controlled switch-variable to be equal or proportional to the control reference in each switching cycle.One cycle control technique features the merit of simple circuit structure,high control precision,fast dynamic response, and control performance not affected by the variable of power parameters.It is very suitable to control switching power amplifier.In this thesis,one cycle controlled switching power amplifier is analyzed detailed in theory and researched in simulation and experiment.Main work and conclusion are described below.First,the basic structure and operational principle of one cycle controlled half-bridge and bridge circuit are analyzed,and control equation are deduced. Small signal model of one cycle controlled bridge switching power amplifier is established.The theory research results of one cycle controlled switching power amplifier show that the output signal follow the input signal linearly,and the control performance is decided by output filter.Second,the results of theory analysis and simulation research show that the output of one cycle controlled bridge switching power amplifier have DC offset because of the nonideal characteristic of reset signal.The magnitude of output DC offset voltage is proportional to width of reset pulse.A voltage compensation technique is used to solve this question,and the computation formula of compensation voltage is gived.The circuit compensated and not are researched through simulation and experiment,which results show that compensated circuit solve the output DC offset effectively.At last, control circuit of one cycle controlled bridge switching power amplifier is improved with the basic idea of one cycle control.The simulation results show that the amplifier of improved control circuit not only solve the question of output DC offset,but also keep the voltage gain lowered by voltage compensation technique.
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