This paper investigates and proposes an efficient control design to address the degradation in the mechanical speed of a traction machine drive (TMD) in an electric vehicle (EV) caused by thermal effects during its operation. Variations in the operating as well as ambient temperature cause unexpected uncertainties in TMD parameters such as stator and rotor resistance, which results in significant degradation in EV's speed performance capability. To mitigate this problem, an output feedback robust linear parameter varying (LPV) controllerobserver set is designed using H∞ control theory that enhances the EV's speed performance in field-oriented control (FOC) frame. The internal stability of the closed-loop control and the L2 gain bound are ensured by linear matrix inequalities. The performance of the proposed control technique is compared with that of conventional FOC, sliding mode control (SMC) and higher order sliding mode control (HOSMC) to validate its efficacy and advantages. The robustness of the proposed control technique is tested for an EV operation against the Worldwide Harmonised Light Vehicles Test Procedure (WLTP) Class 3 driving cycle. The nonlinear MATLAB simulation results guarantee the effectiveness of the proposed controller-observer set. These results are verified experimentally on an induction machine drive setup.
Thermal effects play an important role on the performance of electric motors for the applications in traction/propulsion systems. In these type of applications, there is a feedback loop as well as transients are involved. The torque speed characteristics of the electric motors are dependent upon the motor parameters such as armature/rotor resistance, stator resistance etc. The parameters are significantly affected by the temperature because change in temperature is very high in propulsion systems. As a result, the performance of electric motors used in propulsion systems is degraded. In this paper, the thermal effects on electric motors are combined at one place which is not done before. This will be quite helpful for the researchers of this area to study the thermal effects on the performance of electric motors collectively.
Harmonic current estimation is the key aspect of Active Power Filter (APF) control algorithms to generate a reference current for harmonic compensation. This paper proposes a novel structure for harmonic current estimation scheme based on Trigonometric Orthogonal Principle (TOP) and Self Tuning Filter (STF). The key advantages of the proposed method are its simplicity, low computational burden and faster execution time in comparison to the conventional harmonic current estimation approaches. The TOP method provides a simple and fast approach to extract the reference current, while STF provides a simplified structure to generate the required synchronization signal that eliminates the need of a Phase Locked Loop (PLL) algorithm for synchronization. As a result, it exhibits less complexity in implementation and less consumption of microcontroller's resources; thus, the proposed method can be implemented using a low-cost microcontroller. It is shown in the paper that the proposed method provides 10 times gain in processing speed as compared to the conventional DQ method. The proposed approach is analyzed in detail, and its effectiveness and superior performance are verified using simulation and experimental results.
With higher demand for power electronic converters in single-phase drive systems, the concern for fault-tolerant schemes has risen in the past decade. Also, the demand for Impedance(Z)-source converters, facilitating single-stage power conversion with high voltage gain, has increased for induction motor drive systems. This paper presents an efficient two TRIAC fault-protection technique for the impedance-source half-bridge converter-fed induction motor drive system. The study is analyzed thorougly under pre-fault and post-fault conditions and a comparative analysis is presented in this paper. Simulation circuits with relevant harmonic spectra are assessed. From the detailed analysis, it is found that the occurrence of faults increases harmonic distortion to a high level, making the drive system ineligible for operation. The proposed fault-protection technique proves to be an efficient topology in maintaining continuous power flow during faults.
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