Wide bandgap (WBG) device-based power electronics converters are more efficient and lightweight than silicon-based converters. WBG devices are an enabling technology for many motor drive applications and new classes of compact and efficient motors. This paper reviews the potential applications and advances enabled by WBG devices in ac motor drives. Industrial motor drive products using WBG devices are reviewed, and the benefits are highlighted. This paper also discusses the technical challenges, converter design considerations, and design tradeoffs in realizing the full potential of WBG devices in motor drives. There is a tradeoff between high switching frequency and other issues such as high dv/dt and electromagnetic interference. The problems of high common mode currents and bearing and insulation damage, which are caused by high dv/dt , and the reliability of WBG devices are discussed.

Wide Bandgap Devices in AC Electric Drives: Opportunities and Challenges

The transition to electric road transport technologies requires electric traction drive systems to offer improved performances and capabilities, such as fuel efficiency (in terms of MPGe, i.e., miles per gallon of gasoline-equivalent), extended range, and fast-charging options. The enhanced electrification and transformed mobility are translating to a demand for higher power and more efficient electric traction drive systems that lead to better fuel economy for a given battery charge. To accelerate the mass-market adoption of electrified transportation, the U.S. Department of Energy (DOE), in collaboration with the automotive industry, has announced the technical targets for light-duty electric vehicles (EVs) for 2025. This article discusses the electric drive technology trends for passenger electric and hybrid EVs with commercially available solutions in terms of materials, electric machine and inverter designs, maximum speed, component cooling, power density, and performance. The emerging materials and technologies for power electronics and electric motors are presented, identifying the challenges and opportunities for even more aggressive designs to meet the need for next-generation EVs. Some innovative drive and motor designs with the potential to meet the DOE 2025 targets are also discussed.

Electric Drive Technology Trends, Challenges, and Opportunities for Future Electric Vehicles

Wide-bandgap (WBG) power semiconductor devices have become increasingly popular due to their superior characteristics compared to their Si counterparts. However, their fast switching speed and the ability to operate at high frequencies brought new challenges, among which the electromagnetic interference (EMI) is one of the major concerns. Many works investigated the structures of WBG power devices and their switching performance. In some cases, the conductive or radiated EMI was measured. However, the EMI-related topics, including their influence on noise sources, noise propagation paths, EMI reduction techniques, and EMC reliability issues, have not yet been systematically summarized for WBG devices. In this article, the literature on EMI research in power electronics systems with WBG devices is reviewed. Characteristics of WBG devices as EMI noise sources are reviewed. EMI propagation paths, near-field coupling, and radiated EMI are surveyed. EMI reduction techniques are categorized and reviewed. Specifically, the EMI-related reliability issues are discussed, and solutions and guidelines are presented.

A Survey of EMI Research in Power Electronics Systems With Wide-Bandgap Semiconductor Devices

In high-performance control of ac machines through variable frequency drives, the knowledge of machine parameters plays a decisive role. The accuracy with which machine parameters can be known is directly related to the time and effort put during the testing and commissioning process. In the ever-demanding industrial environments, the time spent on parameter identification translates into loss of production. To reduce commissioning times, research in this direction has focused on automatizing the identification procedure without loss of accuracy. This paper reviews different lines of research adopted over the past few decades for machine parameter identification. Parameter estimation of ac machines is considered because of their widespread applications from servomechanisms to traction to aviation. The surveyed works include self-commissioning schemes that have become an integral part and a salient feature of modern electric drives. This feature enables the drives to automatically identify machine parameters and tune the control loops.

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Parameter Identification and Self-Commissioning in AC Motor Drives: A Technology Status Review

The performances of a model predictive control algorithm largely depend on the knowledge of the system model. A model-free predictive control approach skips all the effects of parameters variations or mismatches, as well as of model nonlinearity and uncertainties. A finite-set model-free current predictive control is proposed in this paper. The current variations predictions induced by the eight base inverter voltage vectors are estimated by means of the previous measurements stored into lookup tables. To keep the current variations information up to date, the three current measurements due to the three most recent feeding voltages are combined together to reconstruct all the others. The reconstruction is performed by taking advantage of the relationships between the three different base voltage vectors involved in the process. In particular, 210 possible combinations of three-state voltage vectors can be found, but they can be gathered together in six different groups. A light and computationally fast algorithm for the group identification is proposed in this paper. Finally, the current reconstruction for the prediction of future steps is thoroughly analyzed. A compensation of the motor rotation effect on the input voltages is proposed, too. The control scheme is evaluated by means of both simulation and experimental evidences on two different synchronous reluctance motors.

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An Effective Model-Free Predictive Current Control for Synchronous Reluctance Motor Drives

In this paper, a novel $dv/dt$ filter is presented targeted for 100-kW to 1-MW voltage source converters using silicon carbide (SiC) power devices. This concept uses the stray inductance between the power device and the converter output as a filter component in combination with an additional small RC -link. Hence, a lossy, bulky, and costly filter inductor is avoided and the resulting output $dv/dt$ is limited to 5–10 kV/ $\mu$ s independent of the output current and switching speed of the SiC devices. As a consequence, loads with $dv/dt$ constraints, e.g., motor drives can be fed from SiC devices enabling full utilization of their high switching speed. Moreover, a filter-model is proposed for the selection of filter component values for a certain $dv/dt$ requirement. Finally, results are shown using a 300-A 1700-V SiC metal–oxide–semiconductor field-effect transistor ( mosfet ). These results show that the converter output $dv/dt$ can be limited to 7.5 kV/ $\mu$ s even though values up to 47 kV/ $\mu$ s were measured across the SiC mosfet module. Hence, the total switching losses, including the filter losses, are verified to be three times lower compared to when the mosfet $dv/dt$ was slowed down by adjusting the gate driver.

An Ultralow Loss Inductorless $dv/dt$ Filter Concept for Medium-Power Voltage Source Motor Drive Converters With SiC Devices

This study presents a self-commissioning procedure for the estimation of the flux linkage curves of synchronousreluctance machines. The procedure exploits a quasi-standstill condition obtained by i ...

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Self-commissioning of flux-linkage curves of synchronous reluctance machines in quasi-standstill condition

This work discusses an online stator resistance estimation method for synchronous machines Multiple improvements are provided with respect to a similar method already been used for induction machines The method is based on the temporary injection of a DC voltage in the machine phases during normal operation The stator resistance estimation is obtained by means of the Ohm's law The proposed scheme works entirely in the stator fixed reference frame, without the need of any machine parameter The selection of the DC injection level is discussed, as well as the countermeasures for reducing the spurious harmonics appearing in the currents and the torque when the machine is speed- and current-regulated In particular, minimum electric loss and minimum torque ripple due to the injection is achieved Moreover, as an alternative to conventional low-pass filtering of the measured signals, it is shown that the resistance estimation can be obtained by averaging the signals over few electric periods Experiments prove the validity of the proposed approach

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Stator reference frame approach for DC injection-based stator resistance estimation in electric drives

This paper presents a novel and fast modelling approach of electrical machines, which is purely based on coenergy only and it is conceived for being directly implemented in the very powerful, yet economical, real-time control architectures of today. The approach does not use any form of time-varying and/or non-linear inductances. A new mathematical formulation of the coenergy is combined with the Finite Element Method (FEM) simulations to investigate the effectiveness of the main idea. A 3kW Synchronous Reluctance Machine (SynRM) is used in this verification. Different operating scenarios are developed and investigated including unbalanced operating conditions with large negative sequence currents. Considerable agreement in machine performance between FEM simulation and the coenergy approach is shown.

Efficient and accurate fully coenergy-based inductance-less FEM model of electrical machines for modern control and identification purposes

The paper analyses a combined current model-voltage model estimator for flux linkages in permanent magnet synchronous machines, with the capability of converging to exact flux estimation even in presence of mismatches because of magnetic saturation. As a trend in next-generation electric drives, the whole algorithm, including both the flux estimator and the standard field-oriented control, has been implemented in a field-programmable gate array (FPGA) chip. Simulations and experimental tests, along with some figures for the FPGA selection, have been included in the study.

Giovanni Zanuso

Papers

An Ultralow Loss Inductorless $dv/dt$ Filter Concept for Medium-Power Voltage Source Motor Drive Converters With SiC Devices

Self-commissioning of flux-linkage curves of synchronous reluctance machines in quasi-standstill condition

Stator reference frame approach for DC injection-based stator resistance estimation in electric drives

Efficient and accurate fully coenergy-based inductance-less FEM model of electrical machines for modern control and identification purposes

Permanent magnet synchronous machines flux linkage estimation with zero steady-state error and its field-programmable gate array implementation