Brushless Series Connected Machine with DC Stator Excitation

Abstract

The brushless DC motors with permanent magnets are used primarily in law power applications. There are no limits on weight and motor dimensions in considered motors with DC stator excitation. Brushless series connected machine with DC stator excitation do not have rotor coils. Field coil and armature coils are mounted in the stator. Armature windings are connected to DC voltage source trough power transistors commutator. Power transistors are controlled by reflective optical sensors in function of rotor position. In the report, the new principle design of the motor with DC stator excitation is considered. The new principle of design supposes individual excitation for each of the armature phase. Such approach gives an opportunity to design electrical machine with any number of armature phases spaced in phase from each other. In series connected DC machines, the field winding is connected in series with the armature winding. In general, the series connection leads to a torque-speed characteristic that is useful in transport and crane mechanisms where need high start torque. For realization series connected machine with DC stator excitation, the number of armature phase can be two, three, or more. Increasing number of phase leads to more complicated design of machine and gives some advantages in performance. The minimum two or three phase gives the simplest design power electronic controller and the sensors position circuit. Like DC universal motor, the machine with series connected DC stator excitation, in principle, can operate from either from AC or DC voltage sources. The universal mode operation is described in this paper when motor operate from one phase AC voltage source. The prototype of two phase motor with DC stator excitation was realized on the base of a car alternator. Results of tests prototype motor and modeling in steady state condition prove that the property of brushless machine with DC stator excitation similar to those series, shunt connected, and separate exited DC machines. Considered machine can find application in the electric drive cars and hybrid electrical vehicles. Copyright © 2012 SAE International.