Power electronics technology has gone through dynamic evolution in the last four decades. Recently, its applications are fast expanding in industrial, commercial, residential, transportation, utility, aerospace, and military environments primarily due to reduction of cost, size, and improvement of performance. In the global industrial automation, energy conservation, and environmental pollution control trends of the 21st century, the widespread impact of power electronics is inevitable. It appears that the role of power electronics on our society in the future will tend to be as important and versatile as that of information technology today. In this paper, the importance of power electronics will be discussed after a brief historial introduction in the beginning. Then, the recent advances of power semiconductor devices, converters, variable-frequency AC drives, and advanced control and estimation techniques will be reviewed briefly. Unlike a traditional technology survey paper, the number of figures is kept intentionally small in favor of the text within the length constraint of this paper. The prognosis of different areas will be highlighted wherever possible based on the author's own knowledge and experience. In conclusion and future scenario, the trend of power electronics and motor drives along with some possible research and development areas will be highlighted.

Power Electronics and Motor Drives Recent Progress and Perspective

Power electronics technology has gained significant maturity after several decades of dynamic evolution of power semiconductor devices, converters, pulse width modulation (PWM) techniques, electrical machines, motor drives, advanced control, and simulation techniques. According to the estimate of the Electric Power Research Institute, roughly 70% of electrical energy in the USA now flows through power electronics, which will eventually grow to 100%. In the 21st century, we expect to see the tremendous impact of power electronics not only in global industrialization and general energy systems, but also in energy saving, renewable energy systems, and electric/hybrid vehicles. The resulting impact in mitigating climate change problems is expected to be enormous. This paper, in the beginning, will discuss the global energy scenario, climate change problems, and the methods of their mitigation. Then, it will discuss the impact of power electronics in energy saving, renewable energy systems, bulk energy storage, and electric/hybrid vehicles. Finally, it will review several example applications before coming to conclusion and future prognosis.

Global Energy Scenario and Impact of Power Electronics in 21st Century

Premium (IEC IE3 Class) efficiency Motors are now mandatory in North America. Super-Premium (IEC IE4 Class) and IE5 Ultra-Premium efficiency classes are defined in the second edition of Standard IEC 60034-30. For line-start fixed-speed applications, Super-Premium IE4-Class Line-Start Permanent-Magnet Motors and Squirrel-Cage Induction Motors are recent entrances in the industrial motor market. For variable-speed applications, IE4-Class Variable-Reluctance Synchronous Motors are also a recent entrance in the market. For the low power range, moving from IE4 to IE5 class, may require moving away from radial-flux induction motor technology, into to the permanent magnet and reluctance technology, either using Rare-Earth or Ferrite magnets. In this paper, efficiency analysis on the best available electric motors and emerging motor technologies, such as axial-flux permanent-magnet synchronous motors, is presented. The potential efficiency gain associated with several design options as well as a study on the theoretical efficiency limit achievable taking into account those existing design options are described.

Beyond induction motors — Technology trends to move up efficiency

This paper presents a cascaded H-bridge multilevel boost inverter for electric vehicle (EV) and hybrid EV (HEV) applications implemented without the use of inductors. Currently available power inverter systems for HEVs use a dc-dc boost converter to boost the battery voltage for a traditional three-phase inverter. The present HEV traction drive inverters have low power density, are expensive, and have low efficiency because they need a bulky inductor. A cascaded H-bridge multilevel boost inverter design for EV and HEV applications implemented without the use of inductors is proposed in this paper. Traditionally, each H-bridge needs a dc power supply. The proposed design uses a standard three-leg inverter (one leg for each phase) and an H-bridge in series with each inverter leg which uses a capacitor as the dc power source. A fundamental switching scheme is used to do modulation control and to produce a five-level phase voltage. Experiments show that the proposed dc-ac cascaded H-bridge multilevel boost inverter can output a boosted ac voltage without the use of inductors.

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DC–AC Cascaded H-Bridge Multilevel Boost Inverter With No Inductors for Electric/Hybrid Electric Vehicle Applications

This paper reviews the progress that has been made in the analysis and design of axial-flux permanent-magnet machines over the past decade, with particular attention to aspects such as electromagnetic and thermal modeling, materials, manufacturing, pulsating torque, and extended speed range. Comparisons with other machine types and applications are also reviewed.

Recent Advances in Axial-Flux Permanent-Magnet Machine Technology

This paper presents a gearless wheel motor drive system specifically designed for fuel cell electric and hybrid electric vehicle propulsion application. The system includes a liquid-cooled axial flux permanent-magnet machine designed to meet the direct-drive requirements. The machine design implements techniques to increase the machine inductance in order to improve machine constant power range and high-speed efficiency. The implemented technique reduces machine spin loss to further improve efficiency. The machine design also optimizes the placement of magnets in the rotor to reduce cogging and ripple torque. An original cooling system arrangement based on the use of high thermal conductivity epoxy joining machine stator and liquid-cooled aluminum casing allows the very effective removal of machine power loss. Design details and experimental results are presented

Application of direct drive wheel motor for fuel cell electric and hybrid electric vehicle propulsion system

A motor traction assembly (2) for a light duty vehicle chassis (3) adaptable for electric traction, in accordance with the invention includes a rotatable wheel (4). The light duty vehicle any automotive car or truck marketed toward and typically used by consumers generally. The light duty vehicle adaptable for electric traction may include vehicles with an electric battery power supply, a fuel cell, or hybrid combinations of a fuel cell, an electric battery power supply or an internal combustion engine. A tire (6) is attached to the wheel (4). The wheel (4) has a radially outer tire support portion (8) and a radially inner hub support portion (10). The radially outer tire support portion (8) and the radially inner hub support portion (10) are cooperatively configured to define a wheel cavity (12) that is axially inwardly open with respect to the vehicle chassis (3) and has a inner wheel parameter (14) and an outer wheel parameter (16). The wheel has an inner side (11).

Wheel motor system

A method of controlling an IPM machine having a salient rotor. Stator terminal signals are measured and rotated to obtain synchronous reference frame current signals. A rotor position is estimated based on an impedance generated using the rotor and included in the current signals. The estimated rotor position is used to control the machine. An alternator-starter system in which this method is used can provide high cranking torque and generation power over a wide speed range while providing operational efficiency.

Terrence G. Ward

Papers

Application of direct drive wheel motor for fuel cell electric and hybrid electric vehicle propulsion system

Wheel motor system

Position-sensorless control of interior permanent magnet machines