Consideration of Boost DC-DC Converter Losses in the Torque Control System of a Hybrid Supervisory Controller

<div class="section abstract"><div class="htmlview paragraph">As the complexity of electrified powertrains and their architectures continue to grow and thrive, it becomes increasingly important and challenging for the supervisory torque controller to optimize the torque commands of the electric machines. The hybrid architecture considered in this paper consists of an internal combustion engine paired with at least one electric motor and a DC-DC switching converter that steps-up the input voltage, in this case the high voltage battery, to a higher output voltage level allowing the electric machines to operate at a greater torque range and increased torque responsiveness for efficient power delivery. This paper describes a strategy for computing and applying the losses of the converter during voltage transformation to determine the optimal engine and electric motor torque commands. The control method uses a quadratic fit of the losses at the power limits of the torque control system and on optimal motor torque commands, within the constraints of the motors and electrical components. This method increases the torque control system’s efficiency, maintains motor torque responsiveness for noise, vibration, and harshness (NVH) mitigation, and optimizes the hybrid supervisory processor’s computation without extra optimization loops. The magnitude of the boost converter losses is typically estimated to be about 10-20% of the overall losses from other electrified components like, electric motors, inverters, low-voltage converters, etc.</div></div>