Temperature dependence of a rectified permanent magnet traction generator

Permanent magnet traction generators are usually used together with a rectifier, which can be of a controlled or an uncontrolled type. While the controlled rectifier offers a degree of freedom for the optimization of the operating point, the uncontrolled rectifier imposes certain restrictions, and the influence of the parameters of the machine becomes more relevant. One of the main parameters is the induced voltage. With the use of rare earth permanent magnets, the induced voltage is to a remarkable extent dependent on the temperature of the magnets. The effect of the temperature on the output parameters of the machine, particularly under the constraints of the uncontrolled rectification, is discussed in this paper. Finally possible solutions to reduce the influence of the temperature are presented. The results, advantages and disadvantages of the use of magnets with a lower temperature coefficient are described.