A Fast and Low-Cost Open-Circuit Fault Detection and Isolation Technique for Three-Phase Dual-Active-Bridge Converters Based on Finite State Machines

As one of popular high-power power interface topologies between the energy storage devices and the dc link, the three-phase dual-active-bridge (3$\Phi$-DAB) dc–dc converter has received increasing attention. However, due to high number of semiconductor devices and multiple possible operation modes in the 3$\Phi$-DAB converters, the reliability and healthy operation become increasingly challenging compared with traditional single-phase DAB converters. This study presents detailed waveform analyses for 3$\Phi$-DAB converters under the normal and open-circuit faulty mode operation. Based on the analysis, a fast, cost-effective, reliable and sensor-less fault detection (FD) and fault isolation (FI) mechanism based on finite state machines for 3$\Phi$-DAB converters is presented in this article. Specifically, switch node voltages between the primary and secondary bridges of 3$\Phi$-DAB converters are adopted as the open-circuit fault (OCF) diagnostic signature and a low-cost OCF diagnostic circuit is utilized to perform the required signal processing. Using this technique, the open-circuit FD was achieved within 1/25th of the switching frequency and the open-circuit FI was performed within 1/6th of the switching frequency, which is the fastest FD and FI time for 3$\Phi$-DAB converters reported so far. Experimental results were acquired from a built prototype under various OCF scenarios to validate the effectiveness of the proposed technique.

I. Introduction

Development of cheap, compact, and more powerful electronics have ushered in a new era where electronic systems are at the heart of almost all types of critical equipment. Lifesaving medical equipment, surgical robots, automatic braking, and control systems of an EV, and nuclear power plants are some examples of these critical applications monitored and controlled by electronic systems. To ensure the high-availability factor of 99.999% for these critical applications [1], power converters, such as dc–dc converters between energy storage devices and the dc link, which are responsible for satisfying the power requirements of these applications and the components within these converters also need to achieve the same level of availability. A thorough survey on the reliability of power converters has pointed out that semiconductors power electronic components are the primary cause of converter failure resulting in converter shut down and loss of service [2].