This paper presents a bidirectional dc-dc converter for use in low power applications. The proposed topology is based on a half-bridge on the primary and a current-fed push-pull on the secondary side of a high frequency isolation transformer. Achieving bidirectional flow of power using the same power components provides a simple, efficient and galvanically isolated topology that is specially attractive for use in battery charge/discharge circuits in dc UPS. The dc mains (provided by the ac mains), when presented, powers the down stream load converters and the bidirectional converter which essentially operates in the buck mode to charge the battery to a nominal value of 48 V. On failure of the dc mains (derived from the ac mains), the converter operation is comparable to that of a boost and the battery regulates the bus voltage and thereby provides power to the downstream converters. Small signal and steady state analyzes are presented for this specific application. The design of a laboratory prototype is included. Experimental results from the prototype, under different operating conditions, validate and evaluate the proposed topology. An efficiency of 86.6% is achieved in the battery charging mode and 90% when the battery provides load power. The converter exhibits good transient response under load variations and switchover from one mode of operation to another. Index Terms-Bidirectional power flow, currend fed push-pull, dc UPS.
In most conventional EV applications, a central high speed electric motor is mechanically coupled to the wheels by a single speed reduction gearbox and a mechanical differential. An innovative alternative utilizes low speed, high torque, gearless, electric motors, mounted completely inside the rim of the wheels, to provide instantaneous torque and eliminate driveline transmission losses. These in-wheel motors have many advantages, including no mechanical linkages and independent and precise torque control of each wheel. Furthermore, advanced control functions like Antilock Braking System (ABS), Anti Slip Regulation (ASR), Electronic Stability Program (ESP), and steering assistance can be easily integrated. In this paper, various motors and control strategies for such in-wheel motor drives for 2-wheel and 4-wheel drive vehicles have been presented.
Many high performance industrial and traction permanent magnet synchronous motor (PMSM) drives require position sensorless operation. Most of the sensorless control techniques are dependent on motor parameters, such as stator resistance, inductance, and torque constant. Thus, the performance suffers greatly in harsh and highly dynamic operating conditions, where the motor parameters are changing. To overcome this problem, Model Reference Adaptive System (MRAS) based algorithms have been developed, which offer adaptive and simple solution.In this paper, an Adaptive Network-based Fuzzy Inference System (ANFIS) based MRAS observer is proposed, where the adaptive model and adaptation mechanism of the conventional MRAS is replaced by ANFIS. The combined capability of neurofuzzy controller in handling uncertainties and learning from processes is proven to be advantageous in modeling highly nonlinear systems. Thus, to neutralize the effect of parameter variations, a novel online tuned ANFIS architecture is developed, which is optimized for Surface PMSM MRAS. This architecture tracks the rotor position and speed accurately in the entire speed range. Furthermore, a detailed comparative simulation and experimental study is carried out for ANFIS and sliding mode observers. The proposed ANFIS based estimation technique shows better performance and immunity to parameter variation compared to sliding mode observer.
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