Investigation on Multiphase Induction Machine for Electric Vehicle

Abstract

This thesis addresses the challenges encountered in six-phase induction machines; such as speed control, common-mode voltage generated in inverter-fed drives, and the development of an integrated battery charger for onboard plug-in electric vehicles (PEVs). Additionally, the thesis suggests several solutions to these current difficulties. This thesis is structured into three main sections. Each of these is briefly described below. The initial section of the thesis focuses on several speed control techniques implemented on multi-phase machines. Although field oriented control (FOC) is often employed and beneficial for various applications, direct power control (DPC) has several benefits that make it especially ideal for demanding applications requiring high performance, high efficiency, and dynamic capabilities. The simplicity, resilience to parameter fluctuations, rapid dynamic response, and diminished harmonic distortion makes it an appealing option for contemporary electric motor control, particularly in fields, such as electric automobiles and industrial drives, where these characteristics are highly prized. This thesis examines the IRRPC and IRFOC methods for controlling the speed of DTIM. The suggested model was implemented in MATLAB, and the results confirmed higher performance of the proposed control approach. The IRRPC is an exceptional control method for IM drive that specifically targets regulating the active and reactive power flow in and out of the induction machine. The IRRPC, an amalgamation of IRFOC and DTC, resolves the limitations associated with the need for torque and flux estimators, which are required for both IFOC and DTC. The recommended approach estimates the instantaneous real and reactive powers using the measured voltages and currents, making it immune to mistakes in motor specifications. The power measurement is performed using actual variables without any transformations. The common-mode voltage (CMV) generated by voltage source inverters (VSIs) poses risks to insulation of the windings, can cause damage to bearings, leads to electromagnetic interference (EMI), and results in leakage currents. Consequently, efforts are undertaken to solve the CMV problems by focusing on PWM techniques employed in inverter-fed drives. An analysis is conducted on the common-mode voltage (CMV) generated by the inverters that power a dual three-phase induction motor (DTIM) drive. A strategy is presented to reduce this value based on active zero voltage vector. The concept of utilizing an active zero state space i vector modulation approach is expanded to reduce the common mode voltage (CMV) in DTIM effectively. The common mode voltage (CMV) is restricted to one-sixth of the DC link voltage, which is lower than the maximum CMV (half of the DC link voltage) generated in traditional space vector modulation (CSVPWM). An equilibrium is also attained between the decrease in CMV and decreased distortion in current. A performance study of the machine is also conducted for different modulation indices. The utilization of the vector space decomposition-based space vector modulation method allows for more flexibility by using an additional degree of freedom in a dual three-phase system to efficiently reduce the common-mode voltage. The suggested technique lowers the common-mode voltage to one-sixth of the DC link voltage, half of the DC link voltage produced in standard space vector modulation. Work carried out in this thesis examines the DTIM’s applicability for onboard integrated charging in plug-in electric vehicles. Propulsion drive components include a dual three-phase machine, inverter, and grid-connected sensors that form the onboard chargers. Integrated onboard chargers minimize electric car costs and space. The machine windings are reconnected to eliminate the charging torque. Adding a tiny paper capacitor allows these windings to be reconfigured as L filters (topology 1) and LCL filters (topology 2), improving THD, line current harmonics, and input power factor. Charging and V2G torque output are also given in detail. Proposed charging strategies are studied for close loop stability. Simulation and testing findings demonstrate the proposed topologies' effectiveness. Drive components include asymmetrical twin three-phase induction machines, AC-DC converters, and DC-DC boost converters, which provide a hybrid integrated battery charger for electric cars. EVs have rooftop solar PV and three-phase grid charging. Reconnecting the rotor must be stationary during charging, thus one set of machine windings is utilized as grid side filters and the other as a boost inductor. Reconnecting machine windings in anti-series and opposite phase sequences cancels the toque entirely in this work. Charging uses four machine windings. Charging from a rooftop solar PV produces no torque as DC current travels through the windings. The control algorithms (PI based) charge the battery pack from the grid and solar PV, allowing power flow from solar PV to battery, grid to battery, and vehicle to grid. Pulsating magnetic fields cause current imbalance, thus a control technique is designed to eliminate it.