Loss minimization of an IPMSM drive using pre-calculated optimized current references

Interior permanent magnet synchronous machine drives provide a high efficiency over a wide speed range together with a high power-to-weight ratio which makes them the first choice in traction applications such as hybrid road vehicles. The energy efficient control of the drive however is a complex task due to changing machine parameters. It can be optimized for every drive individually to achieve maximum efficiency. This work presents an approach to calculate the loss distribution in the machine and the inverter explicitly. Special focus is set on the consideration of magnetic saturation in the stator and rotor iron. The results are used to modify the control strategy that is based on the Maximum-torque-per-ampere trajectory for minimal total losses over the whole speed range respecting the current and voltage limits. The resulting control structure is simple and easy to implement, ensuring operation of the machine with the most efficient stator current vector. It differs from the conventional trajectory and improves the overall efficiency of the drive.