Christopher Mak

Bio: Christopher Mak is an academic researcher from McMaster University. The author has contributed to research in topics: Rotor (electric) & Automotive industry. The author has an hindex of 4, co-authored 5 publications receiving 97 citations.

Automotive Traction Inverters: Current Status and Future Trends

Abstract: Traction inverters are crucial components of modern electrified automotive powertrains. Advances in power electronics have enabled lower cost inverters with high reliability, efficiency, and power density, suitable for mass market consumer automotive applications. This paper presents an independent review of the state-of-the-art traction inverter designs from several production vehicles across multiple manufacturers. Future trends in inverter design are identified based on industry examples and academic research. Wide bandgap devices and trends in device packaging are discussed along with active gate driver implementations, current and future trends in system integration, and advanced manufacturing techniques.

Automotive Power Module Packaging: Current Status and Future Trends

Abstract: Semiconductor power modules are core components of power electronics in electrified vehicles. Packaging technology often has a critical impact on module performance and reliability. This paper presents a comprehensive review of the automotive power module packaging technologies. The first part of this paper discusses the driving factors of packaging technology development. In the second section, the design considerations and a primary design process of module packaging are summarized. Besides, major packaging components, such as semiconductor dies, substrates, and die bonding, are introduced based on the conventional packaging structure. Next, technical details and innovative features of state-of-the-art automotive power modules from major suppliers and original equipment manufacturers are reviewed. Most of these modules have been applied in commercial vehicles. In the fourth part, the system integration concept, printed circuit board embedded packaging, three-dimensional packaging, press pack packaging, and advanced materials are categorized as promising trends for automotive applications. The advantages and drawbacks of these trends are discussed, and it is concluded that a preferable overall performance could be achieved by combining multiple technologies.

External-Rotor Switched Reluctance Motor for Direct-Drive Home Appliances

Abstract: This paper presents the design of an external-rotor switched reluctance motor (SRM)for a direct-drive washing machine application and a comparison with a commercial model. First, a complete review of the state-of-the-art for “washing appliances” has been discussed and design requirements have been analyzed. Secondly, an external-rotor SRM with high number of poles has been chosen to obtain high torque density and power density. Then both, the electromagnetic and thermal performance of the external SRM have been evaluated by finite element analysis (FEA)in wash mode and spin cycle mode operations to confirm that the design fully satisfies the specifications at low and high-power range with high reliability. The mechanical prototype of the SRM has also been provided, which uses the same housing as the commercial benchmark model. Finally, the SRM design for the washing machine application has been validated based on experimental results.

A Comprehensive Analysis of the Acoustic Noise in an Interior Permanent Magnet Traction Motor

Abstract: Modeling and analysis of acoustic noise is one of the important design phases for a traction motor in the noise-sensitive applications, such as hybrid electric vehicles. This paper presents a comprehensive analysis on the acoustic noise and the radial force density harmonics in a 48/8 interior permanent magnet (IPM) traction motor designed for an electrified powertrain. Detailed acoustic modeling and analysis based on the numerical method is presented. The techniques on improving the simulation accuracy and reducing the computation cost of the numerical modeling is also analyzed. The effect of the two-step skewed rotor on the radial force density harmonics is discussed. The sound pressure level waterfall diagram and the analysis of the radial force density harmonics confirm the dominant vibration mode and the dominant harmonics of the radial force density. The acoustic noise analysis process presented in this paper develops the basis for the acoustic noise reduction by optimizing the rotor stepped skew angles.

Design and Analysis of Stator Cooling Channels for an Axial-Flux Permanent Magnet Machine

Abstract: Axial-flux permanent magnet (AFPM) machines are preferred for applications with space limitations due to their high power and torque densities. However, these higher densities lead to increased temperatures due to the higher output power, which results in more losses, in a smaller volume. Reducing the thermal resistance between the heat generating components and the cooling system improves the thermal performance of the machine. This work compares the effectiveness of different cooling designs that are integrated into the stator potting. The heat generated in the stator that needs to be rejected is produced from the copper, core, and bearing losses. The effect of various design parameters on the maximum winding temperature and the pressure drop, if applicable, are also investigated. It was found that the stator potting material has the largest impact on the coil temperature, with a reduction of 17°C seen by improving the thermal conductivity of the material.

A Review on Multiphase Drives for Automotive Traction Applications

Abstract: This article attempts to cover the most recent advancements in multiphase drives (MPDs), which are candidates for replacing three-phase drives in electric vehicle (EV) applications. Multiphase machines have distinctive features that arouse many research directions. This article reviews the recent advancements in several aspects such as topology, control, and performance to evaluate the possibility of exploiting them more in EV applications in future. The six-phase drives are extensively covered here because of their inherent structure as a dual three-phase system, which eases the production process. This article presents different topologies used in dual three-phase drives and the modulation techniques used to operate them as well as the status of using MPDs in traction applications industrially and the upcoming trends toward promoting this technology more.

A Review of Multilevel Inverter Topologies in Electric Vehicles: Current Status and Future Trends

Abstract: Traction inverter, as a critical component in electrified transportation, has been the subject of many research projects in terms of topologies, modulation, and control schemes. Recently, some of the well-known electric vehicle manufacturers have utilized higher-voltage batteries to benefit from lower current, higher power density, and faster charging times. With the ongoing trend toward higher DC-link voltage in electric vehicles, some multilevel structures have been investigated as a feasible and efficient option for replacing the two-level inverters. Higher efficiency, higher power density, better waveform quality, and inherent fault-tolerance are the foremost advantages of multilevel inverters which make them an attractive solution for this application. This paper presents an investigation of the advantages and disadvantages of higher DC-link voltage in traction inverters, as well as a review of the recent research on multilevel inverter topologies for electrified transportation applications. A comparison of multilevel inverters with their two-level counterpart is conducted in terms of efficiency, cost, power density, power quality, reliability, and fault tolerance. Additionally, a comprehensive comparison of different topologies of multilevel inverters is conducted based on the most important criteria in transportation electrification. Future trends and possible research areas are also discussed.

The rise of electric vehicles—2020 status and future expectations

Abstract: Electric vehicles (EVs) are experiencing a rise in popularity over the past few years as the technology has matured and costs have declined, and support for clean transportation has promoted awareness, increased charging opportunities, and facilitated EV adoption. Suitably, a vast body of literature has been produced exploring various facets of EVs and their role in transportation and energy systems. This paper provides a timely and comprehensive review of scientific studies looking at various aspects of EVs, including: (a) an overview of the status of the light-duty-EV market and current projections for future adoption; (b) insights on market opportunities beyond light-duty EVs; (c) a review of cost and performance evolution for batteries, power electronics, and electric machines that are key components of EV success; (d) charging-infrastructure status with a focus on modeling and studies that are used to project charging-infrastructure requirements and the economics of public charging; (e) an overview of the impact of EV charging on power systems at multiple scales, ranging from bulk power systems to distribution networks; (f) insights into life-cycle cost and emissions studies focusing on EVs; and (g) future expectations and synergies between EVs and other emerging trends and technologies. The goal of this paper is to provide readers with a snapshot of the current state of the art and help navigate this vast literature by comparing studies critically and comprehensively and synthesizing general insights. This detailed review paints a positive picture for the future of EVs for on-road transportation, and the authors remain hopeful that remaining technology, regulatory, societal, behavioral, and business-model barriers can be addressed over time to support a transition toward cleaner, more efficient, and affordable transportation solutions for all.

800-V Electric Vehicle Powertrains: Review and Analysis of Benefits, Challenges, and Future Trends

Abstract: Two of the main challenges for electric vehicle (EV) adoption include limited range and long recharge times. Ultrafast charging can help to mitigate both these concerns. However, for typical 400-V battery EVs (BEVs), the charging rate is limited by the practical cable size required to carry the charging current. To reach ultrahigh charge rates of 350 or 400 kW, 800-V BEVs are a promising alternative. However, the design of an 800-V EV requires careful new considerations for all electrical systems. This article reviews the current state of 800-V vehicle powertrain electrical design and performs an analysis of benefits, challenges, and future trends regarding multiple vehicle powertrain components. Specifically, detailed benefits and challenges related to the battery, propulsion motor, inverter, auxiliary power unit, and on- and off-board chargers are discussed.