Development of multi-mode step down DC/DC converters with fault-tolerant capability

This paper proposes a three-switch step-down DC/DC converter with fault-tolerant capabilities. Detection of faults during power converter switching operations is important to avoid failures. In this paper, fault analysis is based on open circuit fault detection (OCFD) techniques. A numerical solution is developed based on the joule-integral principle to design OCFD hardware protection. Under normal operating conditions, either one of the three switching modes, namely, buck, buck-boost, or flyback, is allowed. The two other switches remain in standby mode. All switches share the same output filter component to achieve a single-switch converter operation in any mode. A microcontroller is used to monitor open circuit faults, and identify MOSFET failure and normal operating conditions. If an open circuit fault occurs on the main switch, the other switch will be activated to provide an alternate current path to maintain output regulation. Simulated and experimental results are demonstrated to verify the design and its fault-tolerant operations.