Design of low ripple PWM voice coil motor driver

The fast steering mirror driven by a voice coil motor is a key electromechanical servo component in modern precision imaging and image stabilization systems. The voice coil motor has a high response bandwidth and is prone to torque ripple caused by switching noise when using a PWM driver, which in turn leads to small oscillations of the fast reflector, limiting its contro l accuracy and resolution. Reducing the output current ripple of PWM driver to satisfy the accuracy requirements of fast steering mirror control is one of the key issues in the design of high-precision fast steering mirror drivers. Reducing switch noise through LCCR filters is an effective way to suppress current ripple in PWM drivers. This article proposes a method of calculation for the LCCR filter of a PWM voice coil motor driver which is low current ripple and used by high-precision fast steering mirror. Taking the peak-to-peak current ripple and current loop bandwidth provided by the overall design of the fast steering mirror as the optimization objectives, the LCCR filter is decomposed into two steps: the design of Zobel network and parameter optimization of Butterworth filter. The design results are verified through transfer function simulation. The effectiveness of the design is verified through transfer function testing, and current ripple testing. The designed PWM voice coil motor driver can achieve the 9A driving capacity, with a current ripple of less than 15mA and a current loop bandwidth o f more than 3KHz.