Current Issue : October - December Volume : 2020 Issue Number : 4 Articles : 5 Articles
Hybrid excitation synchronous motor (HESM) offers the advantages of a convenient flux regulation and a wide range of available\nspeeds. As such, it may be conveniently employed in the fields of electric vehicle and aerospace. In this paper, based on a suitable\ncontrol strategy for vector and speed partition, we put forward a speed control method for HESM which shows optimal efficiency.\nOn the one hand, our method aims at minimizing the copper loss by an optimal configuration of the q-axis current, the d-axis\ncurrent, and the excitation current under the constraint voltage at the armature end. On the other hand, we conduct a comprehensive\nanalysis of the effects of the flux-weakening speed coefficient on the operating performance of the motors and suggest a\nself-adaptive control method to regulate that coefficient and further improve the overall performance of the motors, including\ntheir speed-range regulation, their efficiency, and their dynamical properties. The proposed flux-weakening control method has\nbeen assessed by simulations and HESM-driven experiments. Results have confirmed the feasibility and optimality of our method....
A high-input voltage 2-phase series-capacitor (2-pscB) DC-DC buck converter is theoretically analyzed, designed, and implemented.\nA new design approach for an automatic current sharing scheme was presented for a 2-phase series-capacitor synchronous\nbuck converter. The series-capacitor voltage is used to achieve current sharing between phases without a current sensing\ncircuit or external control loop as each phase inductor charges and discharges the series capacitor to maintain its average capacitor\nvoltage constant. A novel isolated gate driver circuit to accommodate an energy storage capacitor is proposed to deliver isolated\ngate voltages to the switching transistors. An I2 control scheme that uses only one feedback path control for the four gate drivers is\nproposed to enable higher voltage conversion. An experimental 110-12V 6A load prototype converter was designed, and its\ncurrent sharing characteristics were experimentally verified....
Variable speed generators can improve overall genset performance by allowing the diesel\nengine to reduce its speed at lower loads. In this project, a variable speed diesel generator (VSDG)\nuses a rotating stator driven by a compensator motor. At lower loads, the stator turns in the opposite\ndirection of the rotor, a process that can be used for purposes like maintaining a fixed relative speed\nbetween the two components of a generator. This allows the diesel engine to turn at a lower speed\n(same as the rotor) and to increase its efficiency. The present research addresses the control of\nthe compensator motor driving the generatorâ??s stator using a variable-frequency drive that adapts\nthe speed to its optimal value according to the load. The performance of the proposed control\nstrategy was tested using a Freescale microcontroller card programmed in C-code to determine\nthe appropriate voltage for the variable-frequency drive. The control algorithm uses a real-time\napplication implemented on an FDRM-KL25Z signal processor board. The control performance\nof a 2 kW asynchronous motor...................
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We study and describe mostly used traditional simplified circuits for full-bridge Zero Voltage Switching-Dual Active Bridge (ZVSDAB)\nconverter and deduce their mathematical model. On this basis, we propose a high-frequency (HF) mathematical model,\nwhich takes into account conduction loss and HF characteristics of the ZVS-DAB converter model. We compare the static and\ndynamic stabilities of the traditional and the proposed HF mathematical model by simulation. Finally, the high-frequency planar\ntransformer (HFPT) with good heat dissipation and the wide band gap (WBG) semiconductor SiC switches with fast switching\nspeed are employed to build a 4.4 kw, 40 KHz experimental prototype to verify the effectiveness of the improved HF circuit of\nZVS-DAB converter. The results show that the proposed HF mathematical model is superior to the traditional one, and it fully\nconsiders the HF characteristics of the circuit and effectively improves the HF oscillation, DC bias, and waveform distortion of the\nZVS-DAB converter....
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