Online Health Monitoring in Digitally Controlled Power Converters

Spacecraft power systems and other mission- critical applications require robust power delivery systems. This paper focuses on two aspects of power converter health monitoring: detecting and analyzing loss-related and frequency response-related changes. Two hardware-efficient algorithms are discussed that can be implemented without any additional sensing points other than those required for operation of the converter and with minimal additional digital hardware. It is shown that available converter operating information can be processed to detect a significant (e.g. 2x) change in the power MOSFET R_ON- In addition, a system identification-based approach with an additional digital pre-fllter is used to extract an accurate and useful frequency response of the converter despite large quantization noise caused by a low-resolution A/D converter. It is shown that this information can be used to accurately monitor the stability margins of the converter. The techniques are verified experimentally on a 90 W 50 V-15 V forward converter with FPGA control.