Browsing by Author "Antaloae, C. C."

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    Feasibility of high frequency alternating current power distribution for the automobile auxiliary electrical system
    (Cranfield University, 2011-04) Antaloae, C. C.; Marco, J.
    This study investigates the feasibility and potential benefits of high frequency alternating current (HFAC) for vehicle auxiliary electrical systems. A 100Vrms, 50kHz sinusoidal AC bus is compared with 14V DC and 42V DC electrical systems in terms of mass and energy efficiency. The investigation is focused on the four main sub-systems of an on-board electrical network, namely: the power generation, power distribution, power conversion and the electrical loads. In addition, a systemlevel inquiry is conducted for the HFAC bus and a comparable 42V DC system. A combination of computer simulation, analytical analysis and experimental work has highlighted benefits for the HFAC power distribution sub-system and for low-torque motor actuators. Specifically, the HFAC conductor mass is potentially 70% and 30% lighter than comparable 14V DC and 42V DC cables, respectively. Also, the proposed cable is expected to be at least 80% more energy efficient than the current DC conductor technology. In addition, it was found that 400Hz AC machines can successfully replace DC motor actuators with a rated torque of up to 2Nm. The former are up to 100% more efficient and approximately 60% lighter and more compact than the existing DC motors in vehicles. However, it is argued that the HFAC supply is not feasible for high-torque motor actuators. This is because of the high energy losses and increased machine torque ripple associated with the use of HFAC power. The HFAC power conversion sub-system offers benefits in terms of simple power converter structure and efficient HFAC/DC converters. However, a significant limitation is the high power loss within HFAC/AC modules, which can be as high as 900W for a 2.4kW load with continuous operation. Similar restrictions are highlighted for the HFAC power generation sub-system, where up to 400W is lost in a 4kW DC/HFAC power module. The conclusion of the present work is that the HFAC system offers mass and energy efficiency benefits for the conventional vehicle by leveraging the use of compact lowtorque motor actuators and lightweight wiring technology.
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    ItemOpen Access
    Feasibility of High-Frequency Alternating Current Power for Motor Auxiliary Loads in Vehicles
    (IEEE Institute of Electrical and Electronics, 2011-02-02T00:00:00Z) Antaloae, C. C.; Marco, James; Vaughan, Nicholas D.
    This paper presents a feasibility study into the application of a 100-V, 50-kHz high-frequency ac (HFAC) network for powering automotive electrical auxiliaries. The study is focused on motor-actuated loads and is divided into two sections. First, the investigation indicates the benefits of replacing low-torque dc motors with lighter and more efficient 400-Hz ac machines for applications such as electric fans, fuel pumps, or blower motors. A comparative examination of commercially available machines indicates space and weight reduction of more than 60%, and efficiency savings between 25% and 100% are possible. Second, the inquiry evaluates the viability of replacing existing dc/ac inverters with HFAC/ ac converters for high-torque ac machines as employed, for example, in electric- power-assisted steering (EPAS) or heating, ventilation, and air conditioning systems. Based on experimental and simulation results for a column-assist EPAS application employing a three-phase permanent-magnet synchronous motor, this paper shows that an HFAC drive is expected to reduce the voltage harmonic content below 50 kHz by at least 10% compared with the dc/ac inverter. However, the disadvantages of the former drive make it less attractive than the existing dc/ac circuit. Specifically, the EPAS motor torque ripple is expected to be approximately 2% higher compared with the dc counterpart drive. Further drawbacks of the HFAC/ac drive include high metal-oxide-semiconductor field- effect transistor (MOSFET) conduction losses, higher voltage harmonics above 50 kHz, and complex control requirements of the inverter. Conclusively, significant HFAC advantages for motor loads can only be attributed to machines with a nominal torque capability that is limited to 2 N ·m. However, given the number of such devices within a typical vehicle, this translates into a possible vehicle mass saving of 30 kg and a potential reduction in fuel consumption by 0.8 L/100 km