Abstract
Three-level converters are the most important technologies used in high power applications. Among these technologies, active neutral point clamped (ANPC) converters are mainly used for industrial applications. Meanwhile, recent developments have reduced losses and increased efficiency by using a hybrid combination of Si-IGBT and SiC-MOSFET switches to achieve hybrid ANPC (HANPC) converters. Open-circuit failure is regarded as a common and serious problem that affects the operational performance. In this paper, an effective fault-tolerant method is proposed for HANPC converters to safely re-utilize normal operation and increase the reliability of the system under fault conditions. Sequentially, regarding different topologies with reference to earlier fault tolerance methods which could not be applied to the HANPC, the proposed strategy enables continuous operation under faulty conditions effectively without using any additional devices by creating new voltage references, voltage offset, and switching sequences under the faulty conditions. Consequently, no additional costs or changes are associated with the inverter. A detailed analysis of the proposed strategy is presented highlighting the effects on the voltage, currents, and the corresponding total harmonic distortion (THD). The simulation and experimental results demonstrate the capability and effectiveness of the proposed method to maintain normal operation and eliminate the output distortion.
Highlights
Most of the efforts on DC/AC converters including the recent developments have been focused on improving renewable energy technologies such as photovoltaic (PV) systems
A creative method was presented to improve the reliability of wind turbine generation (WTG), by proposing an open-circuit fault detection method using back-to-back converters using the Neutral point clamped (NPC) topology as shown in [21] and in [22], while a new hybrid combination including two different types of switches to perform hybrid active neutral point clamped (ANPC) (HANPC) converters has been recently considered by many researchers
This paper proposed an effective method that can be applied for HANPC to recover the healthy operation and eliminate the fault effects on the system without the need for adding any extra devices
Summary
Most of the efforts on DC/AC converters including the recent developments have been focused on improving renewable energy technologies such as photovoltaic (PV) systems. Among the various control switching strategies, better combinations for the same topology used in industrial applications can be achieved by a higher switching frequency by using a wide band gap (WBG) In this regard, a creative method was presented to improve the reliability of wind turbine generation (WTG), by proposing an open-circuit fault detection method using back-to-back converters using the NPC topology as shown in [21] and in [22], while a new hybrid combination including two different types of switches to perform hybrid ANPC (HANPC) converters has been recently considered by many researchers. The systems exhibited low response, higher ripple output, or lower output waveforms (from three to two levels), which would increase the cost and could even reduce the reliability of the inverters and drive systems In these regards, this paper proposed an effective method that can be applied for HANPC to recover the healthy operation and eliminate the fault effects on the system without the need for adding any extra devices. It results in recovering the healthy operation, improving the reliability of the converter’s applications, eliminating the output distortion that clearly appears in the total harmonic distortion (THD), and works on balancing the DC link voltages
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