IEEE Vehicle Power and Propulsion Conference (VPPC), September 3-5, 2008, Harbin, China

Modeling and Control of a seven-phase Claw-Pole Integrated Starter Alternator for Micro-hybrid Automotive Applications A. Bruyere *,**, E. Semail *, A. Bouscayrol *, F. Locment * J.M. Dubus **, and J.C. Mipo ** *

Arts et Métiers ParisTech / L2EP, Lille, France. Email: [email protected] ** Valeo Electrical System, Creteil, France. Email: [email protected]

Abstract—This paper deals with the modeling and the control of a new high power 12V 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.

⎧v0 = L0 d (i0 ) / dt + RS i0 + e0 ⎪ ⎪v S1−d = LS1 d (i S1−d ) / dt + RS i S1− d ⎪v = LS1 d (i S1−q ) / dt + RS i S1−q + eS1−q ⎪⎪ S1−q v ⎨ S 2−d = LS 2 d (i S 2−d ) / dt + RS i S 2−d ⎪v = LS 2 d (i S 2−q ) / dt + RS i S 2−q + eS 2−q ⎪ S 2−q ⎪v S 3− d = LS 3 d (i S 3− d ) / dt + RS iS 3−d ⎪ ⎪⎩v S 3− q = LS 3 d (i S 3− q ) / dt + RS i S 3−q + eS 3−q VDC ichop

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Figure 1. EMR modeling and control of the seven-phase synchronous machine with separate excitation in the generalized Concordia frame 150

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I. SUMMARY In this paper, an original control scheme is developed for a seven-phase starter-alternator. This control scheme is derived from a specific modeling. In the first section, the drive and the experimental set-up are presented: the machine is a seven-phase claw pole synchronous machine with separate excitation, also called Lundell alternator. It is widely used in vehicles because of its low costs of production. This machine is supplied with a seven-leg Voltage Source Inverter (VSI) connected to a 12V battery. In the second section, the modeling of the drive is established in a generalized Concordia frame. This transformation is used to project the model of the sevenphase drive, from a seven-dimensional space to three independent 2-dimensional subspaces (1). Energetic Macroscopic Representation (EMR) (Figure 1. ) is then used to organize the equations in a synthetic way and a control scheme is deduced from this graphical description. In the last section, two controls in generator mode are analyzed. The first one is based on a square-wave modulation of the VSI. The second control is based on a Pulse Width Modulation (PWM). These two control modes are compared in terms of current quality (Figure 2. ). This comparison is made in the stator frame of the machine, and also in the generalized Concordia frames. Smoother currents with the control established in the generalized Concordia frames lead to a smoother measured torque, which allows reducing the noise emitted by the machine at low speed.

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Keywords—multiphase machine, starter-alternator, control, automotive applications, micro-hybrid vehicle

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Figure 2. Phase currents waveform: comparison between the open loop 180° square wave control (a) and the PWM control established in the generalized Concordia frame (b)

II. CONCLUSION A new starter-alternator with seven phases has been developed. The present square-wave control of the VSI allows satisfying the objective on power. Nevertheless, harmonics of currents are not controlled. In this paper, a modeling of the drive has been developed in order to improve the quality of the phase currents and torque waveforms. The interest of this control is shown by the comparison of two kinds of control in terms of quality of currents waveform. Smoother currents with the control established in the generalized Concordia frame lead to a smoother measured torque.

IEEE Vehicle Power and Propulsion Conference (VPPC), September 3-5, 2008, Harbin, China