Development issues of an ISG PM machine and control system

This paper focuses on addressing some practical considerations in developing an ISG PM system for hybrid electric-vehicle (HEV) applications. Extensive practical test results and theoretical analyses are presented and analyzed. Firstly, the ISG PM machine design is discussed in term of the machine size, pole-pair number, permanent magnet flux, inductance, etc. A cost-effective machine design example, which was successfully demonstrated in a mild ISG HEV application, is analyzed. Its performance test results are evaluated. Subsequently, the impacts of the position sensors on the ISG performance are investigated exclusively. Three prominent position sensor candidates are studied in detail to examine their limitation and feasibility for ISG applications. Furthermore, the control related issues are discussed. The torque control of the ISG machine is implemented through vector control algorithm. Flux-weakening control is employed to achieve a wide speed range of constant-power operation. The impact of the inverter DC-link voltage variation is explored. In addition the digital control delay influence and its effective compensation strategy are addressed.