Adaptive signal amplitude for high frequency signal injection based sensor less PMSM drives

High frequency signal injection based sensor less techniques are well proven and reliable techniques to estimate rotor position from low speed to stand still. However these techniques distort motor currents, which introduce torque ripple and acoustic noise. Lower signal injection amplitude reduces torque ripple but increases position estimation error, so correct signal injection amplitude is required for satisfactory drive performance. More over signal injection amplitude required in transients is higher than steady state conditions. In this work signal amplitude is adaptively increased during transients based on rate of change of load and reduced back to original value under steady state. This work reports implementation details and simulation results of adaptive signal injection based sensor less control. Simulation results shows reduction in torque ripple.