Output-Current Measurement of a PWM Inverter with a Tiny PCB Rogowski Sensor Integrated into an IGBT Module

Inverters used in motor-drive and grid-connected applications usually employ current sensors at the output terminal because they have to control the output current. Existing current sensors like the Hall sensor and the current transformer are a constraint to reduce the volume and cost of the inverter. This paper proposes an output-current measurement method of a PWM inverter using a tiny PCB sensor that is based on the so-called Rogowski coil and can be integrated into an IGBT module. The method utilizes the switching current of the low-side switch for reproducing the output current, which allows using the PCB sensor because the switching current consists of high-frequency components. The method uses a single PCB sensor per leg and takes the polarity of the output current into account. Experimental results using a half-bridge sinusoidal PWM inverter verify that the proposed method measures the output current including its fundamental frequency component, switching ripple one, and polarity.