A Lyapunov Approach to Set the Parameters of a PI-Controller to minimise Velocity Oscillations in a Permanent Magnet Synchronous Motor using Chopper Control for Electrical Vehicles

Abstract

This paper deals with a parameter set up of a PI-regulator to be applied in a system for permanent magnet three-phase synchronous motors to obtain a smooth tracking dynamics even though a chopper control structure is included in the drive. High performance application of permanent magnet synchronous motors (PMSM) is increasing. In particular, application in electrical vehicles is used very much. The technique uses a geometric decoupling procedure and a Lyapunov approach to perform a PWM control to be used as a chopper. Chopper control structures are very popular because they are very cheap and easy to be realise. Nevertheless, using a chopper control structure smooth tracking dynamics could be difficult to obtain without increasing the switching frequency because of the discontinuity of the control signals. No smooth tracking dynamics lead to a not comfortable travel effect for the passengers of an electrical vehicle or, more in general, it could be difficult to generate an efficient motion planning if the tracking dynamics are not smooth. This paper presents a technique to minimise these undesired effects. The presented technique is generally applicable and could be used for other types of electrical motors, as well as for other dynamic systems with nonlinear model structure. Through simulations of a synchronous motor used in automotive applications, this paper verifies the effectiveness of the proposed method and discusses the limits of the results.