Corrective frequency compensation for parasitics in boost power converter with sensorless current mode control

For boost power converter with Sensorless Current Mode (SCM) control, the inductor current is acquired by current estimator instead of current sensing. Without consideration of parasitics, the estimator is low-accurate, which affects system Small Signal Model (SSM) and degrades the control performance. In this paper, the issue is studied in frequency domain, and solved by a Corrective Frequency Compensation for Parasitics (CFCP) strategy. First, transfer functions for power converter, current estimator and current mode controller are given for frequency-domain analysis. Second, without consideration of parasitics, conventional proportional integral compensation is used to improve the system stability. Furthermore, with consideration of parasitics, converter main pole is replaced by two poles while a zero emerges at the origin. In order to cancel out the influence, the proposed CFCP strategy adopts a second-order transfer function to correct zero/pole variation induced by parasitics. Finally, steady state performance and transient response of the converter are improved, which are verified by simulations and experiments.