With the requirements for reducing emissions and improving fuel economy, automotive companies are developing electric, hybrid electric, and plug-in hybrid electric vehicles. Power electronics is an enabling technology for the development of these environmentally friendlier vehicles and implementing the advanced electrical architectures to meet the demands for increased electric loads. In this paper, a brief review of the current trends and future vehicle strategies and the function of power electronic subsystems are described. The requirements of power electronic components and electric motor drives for the successful development of these vehicles are also presented.

Power Electronics and Motor Drives in Electric, Hybrid Electric, and Plug-In Hybrid Electric Vehicles

This paper presents a review of recently used direct torque and flux control (DTC) techniques for voltage inverter-fed induction and permanent-magnet synchronous motors. A variety of techniques, different in concept, are described as follows: switching-table-based hysteresis DTC, direct self control, constant-switching-frequency DTC with space-vector modulation (DTC-SVM). Also, trends in the DTC-SVM techniques based on neuro-fuzzy logic controllers are presented. Some oscillograms that illustrate properties of the presented techniques are shown.

Direct torque control of PWM inverter-fed AC motors - a survey

Field-oriented control and direct torque control are becoming the industrial standards for induction motors torque control. This paper is aimed at giving a contribution for a detailed comparison between the two control techniques, emphasizing advantages and disadvantages. The performance of the two control schemes is evaluated in terms of torque and current ripple, and transient response to step variations of the torque command. The analysis has been carried out on the basis of the results obtained by numerical simulations, where secondary effects introduced by hardware implementation are not present.

FOC and DTC: two viable schemes for induction motors torque control

This paper presents a new direct power control (DPC) strategy for a doubly fed induction generator (DFIG)-based wind energy generation system. The strategy is based on the direct control of stator active and reactive power by selecting appropriate voltage vectors on the rotor side. It is found that the initial rotor flux has no impact on the changes of the stator active and reactive power. The proposed method only utilizes the estimated stator flux so as to remove the difficulties associated with rotor flux estimation. The principles of this method are described in detail in this paper. The only machine parameter required by the proposed DPC method is the stator resistance whose impact on the system performance is found to be negligible. Simulation results on a 2 MW DFIG system are provided to demonstrate the effectiveness and robustness of the proposed control strategy during variations of active and reactive power, rotor speed, machine parameters, and converter dc link voltage

/pdf/direct-active-and-reactive-power-control-of-dfig-for-wind-3hgltet7w2.pdf

Direct active and reactive power control of DFIG for wind energy generation

Medium-voltage (MV) induction motors are widely used in the industry and are essential to industrial processes. The breakdown of these MV motors not only leads to high repair expenses but also causes extraordinary financial losses due to unexpected downtime. To provide reliable condition monitoring and protection for MV motors, this paper presents a comprehensive survey of the existing condition monitoring and protection methods in the following five areas: thermal protection and temperature estimation, stator insulation monitoring and fault detection, bearing fault detection, broken rotor bar/end-ring detection, and air gap eccentricity detection. For each category, the related features of MV motors are discussed; the effectiveness of the existing methods are discussed in terms of their robustness, accuracy, and implementation complexity. Recommendations for the future research in these areas are also presented.

A Survey of Condition Monitoring and Protection Methods for Medium-Voltage Induction Motors

Voltage and current control loops play an important role in the performance of microgrids employing power electronics voltage source inverters. Correct design of feedback loops is essential for the proper operation of these systems. This paper analyzes the influence of state feedback cross-coupling in the design of resonant regulators for inner current loops in power converters operating in standalone microgrids. It is also demonstrated that the effect of state feedback cross-coupling degrades the performance of the control loops by increasing the steady-state error. Different resonant regulators structures are analyzed and compared, performing experimental tests to validate the results of the theoretical analysis.

/pdf/current-control-loop-design-and-analysis-based-on-resonant-1zdumy6red.pdf

Current control loop design and analysis based on resonant regulators for microgrid applications

Fully digital AC drives with pulse width modulated inverters are becoming an industrial standard. For PWM inverters several strategies are used. A complete view of the most common carrier based strategies, as sinusoidal PWM, third harmonic injected PWM, discontinuous or dead band PWM and space vector PWM is presented. The authors propose a method based on 'quality factors' to evaluate the different types of modulation. >

Different PWM modulation techniques indexes performance evaluation

In the paper, the possibility of predicting the iron losses with a PWM (pulse width modulation) voltage supply, starting from steel producers data sheets and PWM inverter characteristics, is presented. The proposed methodology is based on an experimental approach to the problem, and it allows good accuracy between the predicted and the measured iron losses on Epstein samples. The proposed method is based on simple equations allowing the prediction of the iron losses in nonoriented magnetic materials, when the thickness of the sheets and the PWM inverter characteristics are known. In the paper, a complete description of this approach is presented. In particular, the most significative experimental results, obtained on magnetic material samples, are included. In addition, results concerning iron losses prediction for PWM inverter-fed induction motors, transformers and inductance cores are presented.

Iron losses prediction with PWM inverter supply using steel producer data sheets

Effect of magnetic cross-coupling in synchronous reluctance motors

The efficiency and loss maps represent an important tool to evaluate an electrical motor drive. The efficiency maps are usually computed using finite element analysis or equivalent circuits that take into account the motor losses. However, these methods need to be compared with efficiency maps that must be experimentally obtained using calibrated instruments. The main problem is how to implement an automated procedure that must obtain the motor or drive efficiency for all operating points. This paper describes an efficiency and loss mapping procedure that has been applied for a 5.3 kW three-phase internal permanent magnet machine prototype for traction applications, but it can be used for any AC machine with inverter supply. All measurements have been performed with an advanced data recorder instrument. The efficiency and loss maps are calculated after the test with a post-processing procedure that can provide all information regarding the motor exploitation, including current, voltage and flux vector trajectories in (d, q) rotor frame.

Michele Pastorelli

Papers

Current control loop design and analysis based on resonant regulators for microgrid applications

Different PWM modulation techniques indexes performance evaluation

Iron losses prediction with PWM inverter supply using steel producer data sheets

Effect of magnetic cross-coupling in synchronous reluctance motors

Efficiency and loss mapping of AC motors using advanced testing tools