Cost-Effective Fault Diagnosis for Motor and Inverter Using Bootstrap Charging and Single DC Link Current Sensor

Motor drive systems in home appliances are meticulously designed with minimal sensors and components to maximize reliability, reduce costs, and minimize size. These systems often operate continuously, making fault detection critical to ensure rapid maintenance and extended system longevity. Among the components, the bootstrap configuration - commonly adopted for driving the upper-side switches - requires charging of the bootstrap capacitor during the initial stage of operation. This paper introduces a novel fault diagnosis method for motor drive systems that leverages a single DC link current sensor and the existing bootstrap topology without requiring additional sensors or circuits. The proposed fault diagnosis is performed during the bootstrap charging phase by observing the current flowing through the sensor. The charging impedance and corresponding current under different fault conditions are analyzed and classified, enabling accurate detection and distinction between motor and inverter faults. Experimental validation demonstrates the effectiveness and practicality of the approach.