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International Journal of Mechanical Engineering and Technology (IJMET) Volume 10, Issue 04, April 2019, pp. 580–587, Article ID: IJMET_10_04_057 Available online at http://www.iaeme.com/ijmet/issues.asp?JType=IJMET&VType=10&IType=4 ISSN Print: 0976-6340 and ISSN Online: 0976-6359 © IAEME Publication Scopus Indexed CONTROL STRATEGY OF DUAL FED OPENEND WINDING PMSM DRIVE WITH FLOATING BRIDGE CAPACITOR A.S. Lutonin, A.Y. Shklyarskiy, Y.E. Shklyarskiy Chair of General Electrotechnic, Saint-Petersburg Mining University, St. Petersburg, Russia ABSTRACT This paper proposes a control strategy of open winding permanent magnet synchronous motor (OW PMSM) in field weakening modes. There are two inverters. One of them connected to the traction battery. Main bridge inverter aimed to provide power with approximately unity power factor, another one to capacitor. Floating bridge inverter aimed to control capacitor voltage on desired value and provide reactive power to the moto. Compare OW PMSM control system with conventional field-oriented control (FOC) shows that proposed method helps to reach speed 1.41 times more than FOC system. FOC system was simulated with 310V DC power supply. OW PMSM with 160V DC power supply and 500 nanofarad capacitor. Key words: OWPMSM, OEWPMSM, SVPWM, Floating bridge, Permanent, magnet, motor, MATLAB, capacitor Cite this Article: A.S. Lutonin, A.Y. Shklyarskiy, Y.E. Shklyarskiy, Control Strategy of Dual Fed Open-End Winding PMSM Drive with Floating Bridge Capacitor, International Journal of Mechanical Engineering and Technology 10(4), 2019, pp. 580–587. http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=10&IType=4 1. INTRODUCTION PMSM motor is widely used in traction applications because of its best mass/dimensional ratio parameters, high efficiency [1,2]. However, one of the main PMSM motors’ problem is rapid torque decreasing while working in high-speed area. In [3-5] paper, special control algorithms to control PMSM motor in field weakening mode were proposed. In [6] L.Chu, et al compared maximum speed dependency on stator winding connection type. Trends showed maximum speed increasing ability with open winding connection mode with flux weakening control algorithms. In paper [7] OW-PMSM with five leg inverters with five leg secondary inverter were presented. In [8] comparing different topologies of OWPMSM motor were presented. Topologies with single power source and with two different power sources with equal voltages is the most acceptable for flux weakening operation. Paper [9] presents topology of OWPMSM motor with two inverters with independent power sources, where algorithms of power sharing between independent sources were presented. Paper [10] describes algorithms of OWPMSM control with electrolytic capacitor connection on the http://www.iaeme.com/IJMET/index.asp 580 [email protected] A.S. Lutonin, A.Y. Shklyarskiy, Y.E. Shklyarskiy secondary inverter’s power side. Research results shows that capacitor helps to reduce backEMF of PMSM motor and increase its maximum operation speed value. This paper represents OWPMSM topology two inverters with DC-source in one side and floating capacitor on the other side coupled to powertrain in order to get presented topology’s dynamic performance. 2. OWPMSM MOTOR MODEL Figure 1. OWPMSM motor equivalent circuit Equivalent circuit of OWPMSM showed on Fig.1. Generally, there is no difference with PMSM with stator star secondary winding connection. PMSM motor equations are given by: Vq Rs Lq V L r q d r Ld iq r f Rs Ld id f (1) where Vd – d-axis voltage; Vq – q-axis voltage; R s – stator resistance; Ld – d-axis selfinductance; Lq – q-axis self-inductance; r – electrical speed; f – PM flux linkage or Field flux linkage; – derivative operator; id – d-axis current; iq – q-axis current. Motor torque can be calculated as Te 3P d iq q id 2 2 (2) where Te – develop torque; P – pole number d –d axis flux linkage; q – q axis flux linkage; Mechanical torque equation is: Te TL B m J d m dt (3) where T L – load torque; B – friction coefficient m –mechanical rotor speed; J – inertia; Equation to convert currents from rotating to stationary axis are following: id sin a i Im q cos a (4) where I m – supply current peak value. a angle can be found from: http://www.iaeme.com/IJMET/index.asp 581 [email protected] Control Strategy of Dual Fed Open-End Winding PMSM Drive with Floating Bridge Capacitor iq a Tan 1 id (5) Peak current value can be found from: I m i d2 i q2 (6) 3. OWPMSM FED BY TWO INVERTERS WITH INDEPENDENT POWER SOURCES On Fig.2 OWPMSM topology with two independent sources is presented. Topology consist of 12 IGBT switches, two equal batteries and PMSM motor. Idm PI Udm Iqm PI Uqm Ud1 Өe m2abc VSC ABC to DQ iabc OWPMSM motor Udc Udqm to Udq1, Udq2 Idm Iqm Idm PI Iqm Ucap DQ to ABC PDFB Ud1 Өe DQ to ABC Ucap VSC Figure 2. OWPMSM control system This control topology consists of the following blocks: Speed, dq current and capacitor voltage PI regulators Udq1 and Udq2 block estimator double SVPWM converters According to [14] control dq voltages for Main and floating bridge can be described by following equations: vq1 vq1a vQcap (7) v d1 v d1a v Dcap (8) vq2 vq1 vqm vQcap (9) vd 2 vd1 vdm v Dcap Where v q1, v d1 (10) - is control voltages for Main bridge inverter; for Floating bridge inverter; v q1a, v d1a v q 2, v d 2 - is control voltages are active vectors for Main Bridge (unity power factor); vQcap, v Dcap are voltage components to control capacitor’s charge level; vectors after PI regulators. Described above elements can be found by: v q1a vqm, vdm - voltage 2 PD i q 3I m http://www.iaeme.com/IJMET/index.asp (11) 582 [email protected] A.S. Lutonin, A.Y. Shklyarskiy, Y.E. Shklyarskiy v d1a 2 PD i d 3I m (12) 2 PDFB i q vQcap 3I m v Dcap (13) 2 PDFB i d 3I m v q1 v q1a vQcap (14) (15) v d1 v d1a v Dcap (16) v q 2 v q1 v qm vQcap (17) vd 2 vd1 vdm v Dcap (18) PD 3 v qmi q v dmi d 2 (19) Where PD - is power demand for Main bridge inverter; iq, id measured stator currents after Park transformation; vq1, vd1 are sum vectors for Main Bridge inverter; vq 2, vd 2 are sum vectors for floating bridge inverter; According to [11] id ,ref can be described as: 2 i d ,ref I MAX I q2 (20) Control system aimed to generate unity power factor from Main inverter and fully reactive power from floating bridge inverter. Vector diagram of this process showed of fig. according to [12]: Figure 3. OWPMSM vector diagram http://www.iaeme.com/IJMET/index.asp 583 [email protected] Control Strategy of Dual Fed Open-End Winding PMSM Drive with Floating Bridge Capacitor 4. SIMULATIONS Simulations were made by Matlab/Simulink software. There are two main blocks: Controller algorithm, Motor, and Load. More detailed view of these blocks are on fig 4, fig 5. Figure 4. System model overview Figure 5. System model overview OWPMSM motor was designed by using Simscape language according to (1)-(6) equations. Other electrical elements are Simscape power system pre-assigned components. Motor parameters are following [13]: Table 1. PMSM motor parameters Machine type Rated motor voltage Rated motor current Rated motor speed Number of pole pairs q-axis inductance d-axis inductance http://www.iaeme.com/IJMET/index.asp SPMSM 310 V 15 A 150 rad/sec 4 0.01557 H 0.01557 H 584 [email protected] A.S. Lutonin, A.Y. Shklyarskiy, Y.E. Shklyarskiy Machine type Flux linkage constant Armature resistance Moment of Inertia Friction coefficient SPMSM 0.2667 Wb 1.1 Ohm 0.005066 kgm^2 0 Simulations were provided in order to compare proposed method with conventional FOC system. FOC PMSM system contains one DC 310V voltage source. OWPMSM control system have two different sources: 160V DC voltage source and 5000 nanofarad capacitor. One can notice, that PMSM with Y connected end windings get stacked on speed approx. 160 rad/sec, while OWPMSM motor has reach controller’s setpoint. Voltage fluctuations, sags in DC link [14] or nonlinear behavior of VFC load [15] were not included in simulations (а) (b) Figure 8. Simulation results: (a) – OWPMSM proposed control system; (b) – conventional FOC PMSM control system Figure 9. Capacitor voltage level http://www.iaeme.com/IJMET/index.asp 585 [email protected] Control Strategy of Dual Fed Open-End Winding PMSM Drive with Floating Bridge Capacitor 5. CONCLUSIONS OWPMSM topology operation mode is following: After capacitor charging, Main bridge inverter generates only active power for PMSM motor, while floating bridge inverter with capacitor generates only reactive power. Fig. 9 shows capacitor charging/discharging process. Simulations result shows proposed controller performance: Ramp level of setpoint was intentionally set on level, which is much higher than motor’s datasheet speed parameter. Conventional FOC PMSM drive system reached its nominal value with approximately 160 rad/c speed, while proposed system with OWPMSM, half DC voltage level (160V) on main bridge and capacitor on floating bridge reached speed about 1.41 times higher than nominal motor’s value. OWPMSM negative current on start-up time shows charging process of floating bridge capacitor Proposed simulation consists only static load on motor shaft. Further researches aimed on vehicle powertrain mounted studies in order to determine suitability of this system to operate electric vehicle in wide speed applications. REFERENCES [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] T. Finken, M. Felden and K. 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