Alain Bouscayrol

Modeling and control of a seven-phase claw-pole integrated starter alternator for micro-hybrid automotive applications

This paper deals with the modeling and the control of a new high power 12 V integrated starter alternator (ISA). This system is used to bring micro-hybrid functions to standard internal combustion engine (ICE) vehicles. The drive is composed of a seven-phase synchronous claw-pole machine with separate excitation, supplied with a seven-leg Voltage Source Inverter (VSI) designed for low voltage and high current. The system is modeled in a generalized Concordia frame and a graphical description is used to highlight energetic properties of such a complex system. A control scheme is then deduced from this graphical description. Two controls are achieved in generator mode and compared: one is using the VSI in a square-wave mode, the other in a pulse width modulation (PWM) mode. Experimental results are provided.

Sensitivity of a 5-phase brushless DC machine to the 7th harmonic of the back-electromotive force

This paper presents a vector control of a 5-phase drive composed of a 5-leg pulse width modulation (PWM) voltage source inverter (VSI) supplying a permanent-magnet brushless DC (BLDC) machine with trapezoidal waveform of the back-electromotive force (EMF). To achieve this control a multi-machine multi-converter model is used: the 5-phase machine is transformed into a set of two 2-phase fictitious machines which are each one controlled in a (d,q) frame as 3-phase machines with sine waveform back-EMF. In comparison with the 3-phase BLDC drives, the 5-phase ones present one particularity: a high sensitivity to the 7th harmonic of back-EMF. Experimental results show that the 7th harmonic of back-EMF, which represents only 5% of RMS back-EMF, induces high amplitude parasitic currents (29 % percent of RMS current). The model allows to explain the origin of this sensitivity and how to modify simply the control algorithm. Experimental improvements of the drive are presented.

Control of a Seven-phase Axial Flux Machine Designed for Fault Operation

This paper deals with control in fault operation of a seven-phase permanent magnet synchronous machine supplied by a seven-leg voltage source inverter (VSI). Using a multi-machine description, a seven-phase machine which presents a special ability to be controlled with only five phases supplied has been designed. The machine is presented and experimental results are provided when two phases are opened. In a first case of no change of classical control, high torque ripples are observed. In a second case, a specific control deduced from the multi-machine modelling is suggested for reducing torque ripples

Identification of a 7-phase claw-pole starter-alternator for a micro-hybrid automotive application

This paper deals with the identification of a new high power starter-alternator system, using both: a finite element method (FEM) modeling and an experimental vector control. The drive is composed of a synchronous 7-phase claw-pole machine supplied with a low voltage / high current voltage source inverter (VSI). This structure needs specific approaches to plan its electrical and mechanical behaviors and to identify the parameters needed for control purpose. At first, a finite element method (FEM) modeling of the machine is presented. It is used for the predetermination of the electromotive forces and of the torque. Experimental results are in good accordance with numerical results. In a second part, resistive and inductive parameters of the drive are determined by an original experimental approach that takes into account each component of the drive: the battery, the VSI and the machine.

Identification of sensitive R-L parameters of a multiphase drive by a vector control

This paper focuses on an experimental method to determine the electric parameters of a seven-phase low-voltage multiphase drive. The drive is a belt driven starter-alternator for powerful cars with hybrid electrical vehicles (REV) functions. The resistive and inductive parameters are necessary to obtain the six characteristic time constants of the control modeling. Classical direct measurements lead to imprecise results because of very low values for the windings electric resistance (a few mOmega) and inductance (a few muH). Effects of the imprecision on the measurements are all the more important that time constants are obtained by a ratio of cyclic inductances by resistance, with cyclic inductances being a linear combination of seven measured inductances. The methodology for identification detailed in this paper is based on a stator current vector control, in a multi-reference frame. This methodology allows us to get directly these time constants. Numerous measurements allow the robustness of the method to be evaluated.