In the domain of classical (FOC, Feedback militarization, ...) and modern (sliding modes, backstepping, high gain, passivity, ... etc) controls of AC machines making the propulsion/traction of HEV/EV, the knowledge of rotor position and speed (figure 1) are required, which are obtained generally by a physical sensor (encoder or resolver). However, mechanical sensors are expensive, bulky, sensitive to the environment (temperature, noise, mechanical oscillations, electromagnetic compatibility, etc.) and reduce the system reliability. The mechanical sensor can be a sign of defects that can lead to the total loss of information or its degradation, resulting in a significant drop in performance and a malfunction of the traction chain. The position/speed estimation (figure 2) by means observers, or estimators, or generally speaking software sensors, becomes an ongoing need on the first part of the Chair Area 1, namely within EV and HEV, either for fault diagnosis and safety applications, or for the closed-loop self-sensing control. The main goal of software sensors is to estimate the position/speed by using only currents measurements of AC machines.
Figure 1: Control principle of AC machines with position/speed measurement Figure 2: Control principle of AC machines without position/speed measurement (using observers, i.e. software sensors)
