Thermal Performance Research of Brushless Doubly-Fed Pulse Alternator Based on Differential Modulated Rotor Winding

Compensated pulse alternators (CPAs) are widely used as a kind of high-power pulse power supply, in which the compensating components can reduce the transient impedance of armature winding, to obtain current pulses with high peak values. In this article, a differential brushless doubly-fed pulsed alternator (BDPA) is proposed, and two sets of windings in the stator of BDPA are decoupled from each other, and each of them is coupled to the self-closing rotor winding. So, when the armature winding is discharged, a compensating current is generated in the rotor and excitation windings, which can increase the discharging current of the armature winding. Due to the absence of brushes, the brushless doubly-fed motor has higher reliability, but the heat generation of an iron core pulse alternator is higher than that of an air core pulse alternator, which may damage the windings in motor, especially brushless doubly-fed motors with three sets of windings. For this reason, the operation mode of periodic intermittent excitation was chosen. The excitation power supply is switched on only when continuous pulse discharges are performed and is switched off for the rest of the time. In this article, a lumped parameter thermal network (LPTN) model is established for a brushless doubly-fed pulse generator, steady-state and transient temperature rises of BDPA are analyzed using this model and compared with the calculation results of finite elements to verify the validity of LPTN model.