| Simultaneous AC and DC power sources with high quality are required in many self-contained electrical power systems, such as those used in aircraft, vessels, mobile communication stations and offshore oil platforms. Those power sources should have the virtues such as simple structure, small size, high reliability and high efficiency of energy conversion. This paper describes the de.sign, parameter calculation, and performance of a PM synchronous generator with multiple winding sets used for self-contained electrical systems, which require simultaneous AC and DC power supply. Compare with traditional wound-field generators, without the field windings and brushes, they have higher efficiency and high torque/volume relationship. There are 3 independent Y-connected windings equipped on the stator, one winding set delivers AC power, and the others are connected to the bridge rectifier to supply DC power. The AC winding is a three phases winding, and the DC winding is a six phases winding composed of two three phases windings shifted by π/6 electrical radians. By incorporating a soft-iron pole piece in the region between the trailing pole edge and the trailing interpolar axis of each pole, a reduction in the voltage regulation of generator can thus be achieved. The implication is that q-axis synchronous reactance drop can be increased.Machine dimensions are determined using the Finite Element Method in 2 dimensions. The voltage regulation is calculated with different soft-iron dimensions. With the magnet field solution, the induced voltage is achieved by a Fourier Series contained several voltage harmonics, which will be used later for the theoretical calculation of the machine performance. The values of the self and mutual inductances, which contained the effects of magnet saturation and inherent harmonics in flux linkages, are calculated directed from magnet field solutions using an energy perturbation approach. Because of the temperature dependent character of the material, a technique in conjunction with coupled magneto-thermal FE field analysis is used to obtain temperature distribution of the machine.The behavior of the generator with three 3-phase stator winding displaced by a angle is analysis by means of an orthogonal transformation of the A, B, C, alf bl, cl, a2, b2, c2 variables into a new set: dl, ql, 011 d2, q2, 02, d3, q3, 03, wherein leakage inductances are included. The differential equations with the new variables have time-independent coefficients. Thus a phasor diagram can be drawn The simulation is based on use of the ABC frame of the reference for development of the necessary equation. This is an advantage over the method that employ the mathematics model in the dqO frame of reference in that no simplying assumptions, such as neglect of magnetic nonlinearities, neglect of space harmonics in the mmfs as well as space harmonics in flux density wave forms or winding flux linkages, are necessary in this approach. The simulation results are checked versus measured values, and a good agreement between the simulation and the measurements are observed.A scheme of wound-field generator used for elf-contained electrical systems is computed. The result shows that the permanent magnet generator presents here has a series of advantage in size, weight, and efficiency over the wound-field generator. |
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