Automatic Multi-Operation Bumpless Mode Switching Type Digital Controller for PWM Power Amplifier Using Load Estimation

Abstract

Robust PWM power ampli¯ers whose transient response characteristics do not deteriorate against an extensive load change and/or direct-current power supply voltage change are needed. A digital robust controller with bumpless mode switching for PWM power amplifiers which can satisfy such demands has been proposed. In this paper a multi-stage switchingtype digital controller is proposed for spreading capacitance load range more and improving transient characteristics for inductance load. In the previous proposed controller, the con¯guration of the controller is the same to all loads. At inductance load, there is a possibility that the transient characteristics may become bad and the speci¯cation may not be satisfied. Therefore, a load current is estimated at inductance load, and the controller which also uses load current for feedback is con¯gured. A inductance is estimated and a controller is switched to this controller bumplessly. In order to extend the range of capacitance load, a controller is increased from two stage to three stage, and these are switched to each other bumplessly. A DSP is implemented to this digital controller. It is demonstrated from experiments that the multi-stage switching type digital controller is realizable and the given speci¯cations are atisfied.