Jean-Marc Dubus

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.

Comparison of 3-, 5- and 7-leg Voltage Source Inverters for low voltage applications

In the context of high power low-voltage applications as starter-generator for automotive, multi-phase drives present the attractive characteristic of reducing the current per phase and per leg. A 5- or 7-phase machine is also more suitable for using concentrated windings, attractive for their short end-windings and subsequently for a higher expected torque-to-volume density. In this perspective, the 5- and 7-leg voltage source inverters (VSI) are compared with the 3-leg VSI. In the first part, for the same set of resistances and inductances coupled in different wye-coupling configurations, we examined the DC-bus currents and the power recovered by the load for a square-wave VSI control: the 7-leg VSI is the more efficient because it makes best use of the harmonics. In the second part, the torque ripples of 3-, 5- and 7-phase drives are compared: the 7-phase drive torque ripples are the lowest ones because of the less sensitivity to the harmonics of the currents. In the last part, a pulse width modulation control is studied, with almost the same voltage harmonics amount as this one obtained with the square-wave mode control. Experimental results are given for the 7-leg VSI either with a passive load or with a 7-phase permanent magnet synchronous motor.

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.

Design & comparison of a conventional and permanent magnet based claw-pole machine for automotive application

This paper presents the design and performance comparison of a conventional claw-pole machine with a permanent magnet based claw-pole machine for automotive application. The magnets are placed in the inter-claw region to decrease the leakage flux and to supply increased magnetic flux in the machine. It has been observed that with the addition of permanent magnets weighing only a few grams, there is a significant increment of more than 22% in output power of the machine. The geometric dimensions of magnets were also varied to verify their effects on performance and it has been observed that with the increase in magnet weight there is a non-linear increment in torque of the machine.

Design and comparison of outer rotor bonded magnets Halbach motor with different topologies

The outer rotor Halbach cylinder motor is designed for hybrid electric vehicle application. The Halbach cylinder is made of bonded magnet and hence the design presented is high torque density motor with low remanence magnet. Different slots poles combinations for double layer tooth coil winding is also evaluated to find the best combination. The Halbach cylinder motor is also compared with different other motor topologies. The outer rotor Halbach motor has the highest torque compared to other topologies over the whole speed range. Variations of inductance and flux linkage of different topologies are also studied and are presented in the article.

Investigation on surface mounted PM machines with magnet recycling concept for hybrid electrical vehicle applications

The global supply of heavy rare earth magnets can become risky with the rocketing demand of rare earth permanent magnet (PM) machines. This paper focuses on the PM Alternating Current (AC) machines with magnet direct-reuse concept, dedicated to mild hybrid vehicle applications. The designs shall both fulfill all the requirements of the applications and the principle of simple magnet disassembly. Several SPM topologies are proposed in that way and the feasibility of implementing recycled magnets on SPMs is investigated.

FEA based analysis on effect of slot pole combination on motor torque and magnet eddy current loss with bonded NdFeB Halbach rotor

The effect of slots poles combination on inductance and torque was investigated on the motor with outer rotor bonded NdFeB Halbach cylinder designed for automotive application. Motor with Halbach rotor has better performance with higher number of slots and poles combination. The magnet eddy loss was calculated and analyzed with different slots poles. The impact of rotor back on the eddy current was also investigated. The eddy loss calculated using 3D FEA models were also compared with 2D and shows a big difference between the two.