Traction Inverter Research Articles

Boosting Input Voltage of Traction Inverter Using Energy Storage Equipment and its Energy-saving Performance

In order to reduce the energy consumption of railway vehicles, we have developed a new kind of energy storage equipment that is connected in series to the DC side of traction inverters. The equipment boosts the input voltage of the traction inverter so that the motor torque increases in the high-speed region and the mechanical brake force decreases. In this paper, we describe the fundamental operation and energy-saving performance of the proposed equipment.

Comprehensive Efficiency Modeling of Electric Traction Motor Drives for Hybrid Electric Vehicle Propulsion Applications

Extensive research done in the recent past has proven that power electronic converters and electric propulsion motors are extremely critical components for modern hybrid electric vehicle (HEV) propulsion applications. Therefore, it is essential that both the traction motor and the associated drive operate at their optimal efficiencies throughout the driving schedule. In typical HEV propulsion applications, the traction motor and the drive are used over the entire torque/speed operational range. In view of this fact, this paper aims at modeling the inverter and motor losses/efficiencies over typical city and highway driving schedules. The noteworthy losses within a typical three-phase dc/ac traction inverter, such as the switching and conduction losses for both the insulated-gate bipolar transistors and the antiparallel diodes, are modeled and simulated over the city and highway driving patterns. An induction motor (IM) is used for a medium-sized sport utility vehicle, which was modeled in the advanced vehicle simulator (ADVISOR) software. The significant IM losses that were considered in the study include the stator copper losses, rotor copper losses, and core losses. Thus, the average efficiencies of both the inverter drive and the induction traction motor are evaluated and summarized under city as well as highway driving conditions. Finally, based on the individual-model-based efficiency analysis, the overall traction motor drive system efficiency is estimated.

Two-Phase Cooling Method Using the R134a Refrigerant to Cool Power Electronic Devices

This paper presents a two-phase cooling method using the R134a refrigerant to dissipate the heat energy (loss) generated by power electronics (PEs), such as those associated with rectifiers, converters, and inverters for a specific application in hybrid-electric vehicles. The cooling method involves submerging PE devices in an R134a bath, which limits the junction temperature of PE devices while conserving weight and volume of the heat sink without sacrificing equipment reliability. First, experimental tests that included an extended soak for more than 850 days were performed on a submerged insulated gate bipolar transistor (IGBT) and gate-controller card to study dielectric characteristics, deterioration effects, and heat-flux capabilities of R134a. Results from these tests illustrate that R134a has high dielectric characteristics and no deterioration of electrical components. Second, experimental tests that included a simultaneous operation with a mock automotive air-conditioner (A/C) system were performed on the same IGBT and gate-controller card. Data extrapolation from these tests determined that a typical automotive A/C system has more than sufficient cooling capacity to cool a typical 30-kW traction inverter. Last, a discussion and simulation of active cooling of the IGBT junction layer with the R134a refrigerant is given. This technique will drastically increase the forward current ratings and reliability of the PE device

Direct Self-Control and Synchronous Pulse Techniques for High-Power Traction Inverters in Comparison

High-power inverters for traction drives employ in the upper range of stator frequency special pulse control methods, optimized synchronous pulsewidth modulation (PWM), mainly in combination with rotor-flux-oriented control schemes, and direct self-control (DSC) which encompasses motor control and pulse pattern generation. The well-known symmetrized sinusoidal PWM is only to be used in the lower speed range. This paper presents and compares exemplarily the stationary behavior of these two control methods; criteria are inverter peak current, motor harmonic losses, torque ripple, and DC-link harmonics. For these low switching frequencies DSC shows, in spite of its simplicity, a very good overall performance, mainly by avoiding the imperfect use of switching frequency by the synchronous pulse patterns.

Electric Motors for Light Traction

Modern electric motors for road electric vehicles (automobiles, scooters, bicycles), light rail transit (street cars, trolley lines, subway trains), guided transit systems and elevators have been discussed. The paper aims at various types of rotary brushless motors, direct electromechanical drives and practical solutions to light traction systems. Modern permanent magnet (PM) motor technologies offer diversity of cutting-edge technology brushless motors, i.e., motors with one slot coil pitch windings, transverse flux motors, coreless disc type motors and PM assisted synchronous reluctance motors. There is a wide interest in liquid cooled traction motors and inverters as those apparatus minimize the volume of electromechanical drive systems and increase their power density. Frequently, the traction motor for road vehicles is integrated with a solid state converter. Light traction with linear motors has not been considered. Although induction motors are the most popular motors, PM brushless motors are more efficient, more compact, have better steady-state and dynamic performance at low speeds and are excellent motors for direct drive traction application.

Monster motion [power semiconductors

In recent years, high voltage drives and controls including inverters for traction control and high power drives for industrial motion control have adopted emerging technologies to meet cost, reliability and efficiency needs. Take, for example, the gate turn-off thyristor (GTO). This device has led to the use of cheap, robust asynchronous AC motors in variable speed control applications. Later developments brought us the gate commutated thyristor (GCT). This simplifies the gate drive and snubber circuit requirements of GTOs. Meanwhile, power insulated gate bipolar transistors (IGBT) are also taking great strides forward and are now being used with 1000 to 1500 V DC links. And now that injection enhanced insulated gate bipolar transistors (IEGTs) have demonstrated satisfactory performance at DC blocking voltages as high as 6.5 kV, designers can exploit the switching advantages of transistor technology in traction and industrial inverters while also optimising the DC link voltage for maximum power conversion efficiency.

Power module lifetime estimation from chip temperature direct measurement in an automotive traction inverter

Power module lifetime estimation from chip temperature direct measurement in an automotive traction inverter

Recent advances in power electronics technology for industrial and traction machine drives

This paper presents a review of the state of the art of power electronics technology in both industrial and traction drive application. Key development trends include the dominance of AC adjustable-speed drives in new applications, with the squirrel-cage induction machine as the preferred machine in most cases. Particularly striking has been the rapid ascendance of the insulated-gate bipolar transistor (IGBT) as the predominant power switch in both industrial and traction applications ranging from fractional kilowatts to multimegawatts. Key current issues such as industrial drive input power quality and the effects of fast IGBT switching transients on the machines and electromagnetic interference (EMI) production are reviewed. Developments in electric traction for both rail and road vehicles are discussed, including the increasing modularity of new traction inverters in all sizes and the market introduction of new hybrid vehicles using advanced power electronics. The paper concludes with a discussion of expected future trends in power electronics technology that will likely expand the markets for industrial and traction drives during coming years.

Stability Analysis of Permanent Magnet Synchronous Motor Traction Main Circuit with Regenerative Braking on Insufficient Load's Power Consuming

The regenerative braking method has been employed in DC-fed electric railway vehicle traction system in order to reduce energy consumption. The load's power consuming is sometimes insufficient for the regenerated power, and it causes the input voltage of traction inverter rises. In such a case, the regenerative current is regulated to prevent the over voltage. However, in applying this regulation, especially to the permanent magnet synchronous motors (PMSM) traction system, a continuous oscillation of regenerative current is sometimes observed. Unfortunately, It deteriorates passengers' riding comfortability due to torque fluctuation.On this paper, we analyze the phenomena of the oscillation of regenerative currents and suggest an anti-oscillation regenerative current regulation method based on the analyzing results. The detail is as follows.(1) We construct a nonlinear time-varying model, which consists of the substation, power feeding system and the main traction circuit onboard and divide the nonlinear time-varying model into four linear time-invariant systems.(2) Through the analysis with the models, we make it clear that the continuous oscillation is caused by the traditional regenerative braking control method(3) Based on the analysis we suggest a novel anti-oscillation regenerative braking control method, whose effectiveness is proved through experiments.

Accelerated life testing of a traction inverter

The introduction of new technology into equipment brings with it the risk of long-term reliability problems. Manufacturers need to review methods of type testing to reflect the changing properties of inverter technology. The introduction of a traction drive using insulated gate bipolar transistor semiconductor switches to trains for the Northern Line of London Underground represented such a change in technology. The failure of IGBTs under conditions of deep thermal cycling is well documented and it was uncertain as to whether the stresses of station-to-station running would give rise to such a problem, so a life test was devised.

On-chip reliability investigations on power modules actually working in inverter systems

The paper contains the results of temperature measurements for reliability investigations on IGBT modules actually working in inverters for industrial and traction applications. For this, the chip temperature and its transient behaviour have been monitored under different driving conditions of the inverters. Specially prepared IGBT-modules have been used to investigate the industrial and the traction inverters in their electrical and thermal behaviour. The measurement techniques were suitably adapted to the different configurations of the two inverters.

Modelling of inverter-controlled asynchronous drives for system simulation in DC railways

AC inverter drives are being increasingly used for DC-supplied railways. Since simulation techniques are now routinely used for the system design of railways, there is a need to accurately model this type of equipment which is being introduced by several railway organisations. This paper describes models developed for representing the tractive effort and the DC electrical terminal characteristics of inverter-controlled asynchronous drives, for the variable voltage conditions encountered in DC-supplied railways. The models are based upon closed-loop control strategies normally used for traction inverter drives. The models can also be used, with minor modifications, when asynchronous AC drives are used for AC-supplied railways.

Power transistors in variable speed drives

Since the mid-1960s, thyristors have become established as the power control element in applications from domestic lighting and washing-machine controllers to d.c. rolling-mill drives and inverters for alternator starting, with ratings up to at least 10 MW. During this period, transistors were also evolving into types suitable for power control. Today, British-developed 500 V 300 A transistors are being applied to d.c. servo drives and inverters for multiple-unit traction drives. In application to both a.c.- and d.c.-motor drives, the fast switching capability of transistors can have advantages over thyristors, and we shall see it grow as an alternative power controller