Auto Injection Control for In-Circuit Frequency Response Measurement

In-circuit frequency response measurement of power converters enables verification of the control loop and periodic measurement during normal operation of the converter. This enables addition of diagnostics and monitoring functions without additional cost. The disturbance injected for frequency response measurement causes output of the converter to be disturbed, which is undesirable during normal converter operation. This paper presents an auto injection control algorithm by which the disturbance amplitude is controlled while maintaining good measurement fidelity. A voltage source inverter is selected as a case study to test the proposed algorithm, in which both current and voltage loop are verified using in-circuit frequency response analysis measurement.