Safe Phase Current Measurement for Motor Control Applications

As the automotive industry progresses towards electrification, driven by need for sustainability and reduced emissions, the traction inverter emerges as pivotal component of electric vehicles (EVs). Serving as the interface between the vehicle’s control systems, motor and battery. The traction inverter’s performance directly impacts the efficiency, sustainability and overall functionality of electric drive systems. A critical function of the traction inverter is measurement of phase currents in each motor phase, enabling precise control of the motor’s torque and rational speed. This capability is essential for optimizing efficiency, enhancing performance and ensuring safety key aspects of modern electric vehicle technology. This paper introduces method for measuring phase currents in Permanent Magnet Synchronous Motors (PMSM) utilizing the Enhanced Versitile Analog-Digital-Converter (EVADC) integrated within Infineon’s Aurix Tricore. This technology preferred for its rapid conversion speed and advanced features for synchronization and parallel sampling. This approach facilitates synchronous three phase motor current measurement at the midpoint of the Pulse Width Modulation (PWM) trigger signal. By capturing data at this critical point, we effectively eliminate current ripples, which is crucial for accurate motor control technique such as Field Oriented Control (FOC), thereby enhancing the management of torque and rotational speed. Moreover, this work adheres to redundancy principles aimed at preventing single point failures. By implementing critical safety metrics and confirmations measures (SPFM and LFM) necessary for compliance with ISO26262 standards. Redeundnacy checks on measured phase currents support error mitigation, fault detection and overall system safety. This comprehensive approach contributes to advancement of electric vehicle technology but also emphasizes the importance of robust phase current measurement techniques achieving greater reliability and efficiency in electric vehicle operation.