Design of a high frequency switching amplifier for smart material actuators with improved current mode control

A high frequency switching amplifier using current mode control strategy is designed and developed to drive the newly developed smart material actuators. Different from ordinary PWM converters, this kind of switching amplifier typically deals with a reactive load, which usually gives the amplifier a low current loop gain for low frequencies. This low current loop gain usually results in a poor closed loop output current to input reference signal frequency response. By using average current mode control technology, a new switching amplifier design is presented in this paper that has a boosted low frequency current loop gain, thus, the new design has a very flat output current to input reference signal frequency response. Both small signal model analysis and experimental prototyping is done for this design, and they prove the effectiveness of average current mode control in the design of a switching amplifier for smart material actuators.