Powertrain 48V Power Supply Proposal and Safety Validation Voltage Levels for BLDC Motor Driver ASIC

Abstract

This paper presents a design proposal for 48V power supply for a BLDC (Brushless Direct Current) motor driver chip. The BLDC actuator is used in 48 V mild hybrid Powertrain in target applications such starter generator or electric oil pump where the safety is very relevant. The focus is set on the design experience faced during testing the required voltage levels for BLDC driver ASIC (application specific integrated circuit): 48V, 12V, 5V and 3V3. The performance in terms of normal functioning, under-voltage (UV) and overvoltage (OV) has been investigated and validated by the experimental activities. Furthermore, the FTTIs (Fault Tolerant Time Intervals) were monitored in order to give evidence that the safety mechanism successfully avoid violation of proper functioning of the BLDC actuator. In case of safety relevant faults such OV or UV, the BLDC driver has to achieve a safe state within FTTI. There are two safe states available: the BLDC driver will put the inverter in high impedance or the inverter will be driven to break the motor.