Inverterless high power interior permanent magnet automotive alternator

Abstract

Abstract-This paper describes a high-power brushless interior permanent-magnet (PM) automotive alternator which does not use an inverter. The "inverterless" alternator is designed with a high back electromotive force voltage and high reactance, and acts as a constant current source over much of its wide constant power operating speed range. In this configuration, a switched-mode rectifier can be used to regulate the dc output voltage and current, which avoids the complexity and high cost of an inverter. An analysis of the modeling and performance of interior PM machines in this inverterless topology is described. Experimental results showing an outstanding constant power speed range are presented for a 6-kW concept demonstrator machine tested using a three-phase resistive load to simulate inverterless operation.

Modelling of saturation and cross-saturation effects in an interior PM automotive alternator

“…Measured d-axis and q-axis inductance saturation curves for the machine without magnets, with ferrite magnets and with rare-earth magnets. 2 Saturation effects are also evident in the d-axis. With the reluctance rotor, the machine shows very high initial values of d-axis inductance, however, for larger values of stator current, the rotor bridges (see Figure 3) quickly saturate and the d-axis inductance drops rapidly.…”

“…The calculated output power was obtained from the inductance saturation curves and rare-earth rotor magnet fl ux using the standard d-and q-axis interior PM machine equations assuming a limited output voltage and current. 2 The calculated output power at 1,800rpm for the four cases is shown in Table 2. The high power alternator's idle speed requirement is 4kW at 1,800rpm (assuming a 3:1 belt ratio).…”

“…2 This was designed for a 3:1 belt ratio between the engine and the alternator, which results in an alternator operating speed range from 1,800rpm to 18,000rpm.…”

“…In the alternator application, the machine was operated with a rated current of 9.4A to achieve the desired 6kW output power. 2 The rotor has three fl ux-barriers per pole and uses ten small slot bridges per pole for mechanical strength. Figure 1 shows the stator and rotor lamination crosssection.…”

A Control Strategy for Output Maximisation of a PMSG-Based Variable-Speed Wind Turbine

“…In [6], the current vector of an interior type PMSG is controlled to optimize the wind turbine operation at various wind speed, which requires six active switches to be controlled. Switchmode rectifier has been investigated for use with automotive alternator with permanent magnet synchronous machines [8,9]. The switch-mode rectifier has also been investigated for small scale variable speed wind turbine [10,11].…”