Fault-tolerance Strategies for Power Converters

The widespread use of power electronics-based converters has resulted in continuous improvement in the power switches' reliability. The previous authors shows a failure rate of medium-power IGBT modules of 0.1 failures per 106 h, many critical applications need further assurance of operation. This chapter has shown a sample of the techniques used to increase the system operating range under adverse conditions. Some techniques are applied before the onset of a device's fault, by allowing the device to move out of line for “recovery.” Other techniques modify the topology, either by disabling the faulty devices or by also including extra elements to replace the faulty ones. In most cases, this operation needs a corresponding change in the control strategy, as well as in the amount of power that the system can handle during this fault-tolerant operation.