Modified SVPWM Scheme for Fault-Tolerant Control of AC-DC PWM Converter

This article proposes a new SVPWM-based fault-tolerant control (FTC) approach for a three-phase two-level ac-dc converter. Voltage vectors deviation and affected voltage space sectors under faulty conditions are first analyzed. Then, a 12-sector division-based FTC approach is proposed. With the division scheme, sectors affected by faulty switches can be effectively separated from unaffected ones, and SVPWM strategies are implemented to compensate for distorted reference voltage vector in each sector. The scheme to determine the compensation ratio of vectors is also provided to maximize fault-tolerant performance. Six types of defined failure modes, including single and multiple switch faults, are analyzed and tested in experiments. Evaluations on results of current averaged total harmonic distortions, fluctuation of generator speed, torque oscillations, and stability of dc-link voltage verify its capability to achieve maximum system recovery. The approach proposed is an SVPWM-based method for ac-dc converters that require no additional hardware equipment and provide an effective and low-cost fault-tolerant solution.