Study On Novel Hybrid Excitation Claw Pole Machine And Flux-weakening Speed Regulation

Hybrid Excitation Claw Pole Machine (HECPM) is a new type of claw pole machine and its excitation magnetomotive force (MMF) is provided by the field winding and permanent magnets. The claw pole machine has the advantages of simple structure, easy to manufacture and low cost. Electric excitation claw pole machine can regulate the excitation field by adjusting excitation current easily, but there are faults such as the high leakage flux, high loss of excitation and so on; Traditionally, the magnet field of permanent magnet synchronous motor is unable to adjust, and the flux weakening control is often to increase the direct axis current, it helps to broaden the speed range but it rises the problems of copper loss increase and permanent magnet demagnetization at the same time; HECPM takes the advantages of both the electric excitation claw pole machine and the permanent magnet machine, which can easily adjust the excitation and has good performance as well as high research value.This paper mainly studies a new type of hybrid excitation brush-less claw pole machine. The shape of the claws is modified to be right-angled trapezoid, which is convenient for the installment of PMs and therefore reduces effectively the leakage flux between the claws; besides, the electric field winding and excitation bracket are weld on the machine case and eliminates the brush-slip rings structure, therefore enhances the reliability of the machine. This paper studies several aspects of HECPM such as the structure characteristics, the three dimensional field analysis, magnetic circuit calculation, inductance measurement, and the choice of excitation control method. The main contents of the paper are as follows:1.This paper introduces the historical change and development trend of machine excitation system, and reviews the research status of the HECPM from two aspects as the claw pole machine and the flux weakening control of hybrid excitation machine.2. A new HECPM of right-angled trapezoid shaped claws is studied. Firstly, the structure characteristics and working principle are discussed. The paper studies the air gap magnetic field regulation principle on the basis of magnetic field distribution analysis. Then, both the static and the transient 3-D FEM models of HECPM are established, the inner magnetic field distribution changing laws for different excitation MMF are obtained, and the no-load characteristics are analyzed. Finally, the no-load tests of the HECPM are carried out and that verifies the correctness of the FEM simulation results.3. Considering the three dimensional magnetic field distribution of HECPM, an improved magnetic equivalent circuit (MEC) network model is developed. It calculates the permeance of each segment of the machine and the machine can be simplified as a magnetic network. A nonlinear node magnetic potential equation is set up based on the model. Programming the MEC algorithm using Matlab and the no-load magnetic field can be obtained.4. The relationships between inductance parameters of HECPM are analyzed and summarized based on the direct armature reaction theory and constant power coordinate transformation. The inductance tests of the HECPM are carried out.The testing results compared with the FEM simulation results is convincing and therefore verifies the validity of the tests.5. The dqO mathematical model of HECPM is deduced. The open loop speed regulating system simulation model of HECPM is developed using Matlab/simulink, and the excitation regulation module is designed. The regulation characteristics of HECPM at low speed or high speed are analyzed. Compare to the machine without excitation regulation module, the HECPM with excitation regulation module has wider constant power operation range.