Performance Improvement of Direct Torque Controlled Interior Permanent Magnet Synchronous Motor Drive by Considering Magnetic Saturation

Transcription

1 Performance Improvement of Direct Torque Controlled Interior Permanent Magnet Synchronou Motor Drive by Conidering Magnetic Saturation Behrooz Majidi * Jafar Milimonfared * Kaveh Malekian * *Amirkabir Univerity of Technology (Tehran Polytechnic), Center of Excellence in Power Sytem, No. 424, Hafez Ave., Tehran 15914, Iran. Correponding author: bmx@aut.ac.ir Abtract The influence of magnetic aturation on the maximum torque per ampere trategy in contant torque region and field weakening trategy in contant power region for a direct torque controlled interior permanent magnet ynchronou motor drive are dicued in thi paper. In other word, by conidering magnetic aturation, all optimal trategie and motor-inverter limitation are derived in the T ψ plane to apply in the direct torque control method. Thee trategie that take magnetic aturation into account and determine the optimal torque and flux command are derived and implemented in direct torque control method. Simulation reult on a prototype interior permanent magnet motor are included to validate the uefulne of the work. Index Term Direct torque control, field weakening trategy, interior permanent magnet ynchronou motor, magnetic aturation, maximum torque per ampere trategy. I. INTRODUCTION ECENTLY, the Interior Permanent Magnet Synchronou R Motor (IPMSM) i widely ued in high performance application due to ome it advantageou uch a high torque to current ratio, high power to current ratio, high efficiency, low noie, and robutne [1]-[3]. In high performance variable peed drive ytem, the motor peed hould cloely follow pecified reference trajectory regardle any load diturbance, parameter variation and any model uncertaintie [4]. In addition, in ome application, wide-peed operation of electric drive i deired [5]-[8]. In other word, operation in both contant torque region and contant power region i needed. The optimal behavior of drive can be achieved by conidering Maximum Torque per Ampere (MTPA) trategy below the bae peed and Field Weakening (FW) trategy above the bae peed. It hould be noted that the MTPA and FW trategie mut be modified in order to conider magnetic aturation. Thi paper focue on optimal torque control of direct torque controlled interior permanent magnet ynchronou machine capable of operating in both the contant torque and the contant power region. In the Interior Permanent Magnet (IPM) motor, ince the effective air-gap length on the d-axi i large and the relative magnetic permeability of the Permanent Magnet (PM) i cloe to unity, the variation of the correponding magnetizing inductance, L d, due to magnetic aturation, i minimal. On the contrary, the effective air-gap length on the q-axi i mall, and, therefore, the aturation i ignificant [9], [10]. II. MOTOR DYNAMIC BY CONSIDERING MAGNETIC SATURATION The mathematic model of IPMSM in the rotor reference frame can be obtained from ynchronou machine model. Due to contant field produced by permanent magnet, the field variation i zero. In thi paper it i aumed that: Magnetic aturation i coniderable; Core loe are negligible; The induced EMF i inuoidal; and There i no dampener winding on rotor. Uing thee aumption, the voltage and torque equation could be written a, V q 0 q R ωre Ld i i q plq = + V ωre Lq R 0 i d i d q pl d Lq 0 piq ωreψ + + f 0 L 0 d pi d 3Pψ Te = [2ψ f Lq in δ ψ ( Lq Ld ) in 2δ ] 4Ld Lq T = T + Bω + Jpω e L rm rm ω rm 1 = ωre P where, V, V are the q- and d-axi voltage; L, q d q L are the q- d and d-axi inductance; iq, id are the q- and d-axi current; R i the tator reitance per phae; ψ i the contant flux f linkage due to rotor permanent magnet; ψ i the tator flux (1) (2) (3) (4) /08/$25.00 c 2008 IEEE

2 δ ω ω = < = β > β < > Ω ω ω ω ψ θ ψ ω θ th International Power Electronic and Motion Control Conference (EPE-PEMC 2008) 779

3 ψ ψ ψ = ψ + ( ) ( ) ψ = + + ψ = + = + = ψ ψ ψ ψ th International Power Electronic and Motion Control Conference (EPE-PEMC 2008)

4 ψ ψ = + ψ ψ + = < = β > ψ = + = ω = ω + ω ψ = ψ ψ ψ th International Power Electronic and Motion Control Conference (EPE-PEMC 2008) 781

5 ψ ψ + = ω ( ) ( + ψ ) ψ = ω ψ = = = th International Power Electronic and Motion Control Conference (EPE-PEMC 2008)

6 ψ th International Power Electronic and Motion Control Conference (EPE-PEMC 2008) 783