|Ataur Rahman||Department of Mechanical Engineering, International Islamic University Malaysia, 50728 Kuala Lumpur, Malaysia|
|Nurul Hassan||Department of Mechanical Engineering, International Islamic University Malaysia, 50728 Kuala Lumpur, Malaysia|
|Sany Izan Ihsan||Department of Mechanical Engineering, International Islamic University Malaysia, 50728 Kuala Lumpur, Malaysia|
Epicyclic transmission (ET), five-speed manual gearbox (5-SMT), automatic transmission (AT), and continuously variable transmission (CVT) are all possible transmission options for electric vehicles (EVs). The ET is so complex that motorists may be unaware that they are in gear. As the 5-SMT, AT, and CVT transistors are heavier, they consume more energy. Although a single-speed gearbox is lighter, it is not capable of developing enough torque for acceleration. Therefore, this study presents a fuzzy-logic-controlled electromagnetic two-speed gearbox (AEM-2SGB) model for EVs. The electromagnetic actuator is modelled in terms of electromagnet size, number of coil turns, supply current, and electromagnetic force needed to shift gears. The parametric analysis of AEM-2SGB is conducted using Matlab Simulink and a fuzzy simulation model. According to the results, the AEM-2SGB has a first-gear shift time of 110 ms at 300 Nm motor torque and a second-gear shift time of 116 ms at 110 km/h vehicle speed, with a maximum current supply of 16 A using a 24 V lithium ion battery. The AEM-2SGB reduces weight by 37%-66%, transmission losses by 40%–90%, and battery life by 5%.
AI-embedded IoT controller; Compact and low-cost transmission; Electromagnetic gearbox; Energy efficient; Fuzzy logic controller
The market share of electric vehicles (EVs) will be boosted by their ability to reach higher ranges and their target to increase design efficiency and reduce manufacturing costs to become affordable to more customer segments (Bottiglione et al., 2014). In one study, the adoption of two-speed transmission over single-speed transmission gave rise to a reduction in energy consumption over numerous driving cycles of up to 4% for the case study vehicles (Jose et al., 2021). The power transmission of Evs mostly a single-speed transmission system, while MT, AT, and CVT are the transmission options for hybrid electric vehicles (Miller, 2006; Jaafar et al., 2020). A novel two-speed inverse automated manual transmission was examined, and the gear ratios were optimized using dynamic programming. Gear shift control was addressed, and a smooth shift process without a torque hole was achieved through feed-forward and feed-back control of the clutch and the motor. The performance of a two-speed transmission EV was compared with that of an EV with a fixed-ratio gearbox, and two-speed automated manual transmission with a rear-mounted dry clutch was found to have better performance in terms of acceleration time, maximum speed, and energy economy (Spanoudakis et al., 2019). It has two main advantages. When using two-speed transmission, the first gear ratio can be chosen to increase the low-speed torque to improve acceleration on a road grade, while the second gear ratio is for cruising (Miller, 2006).
The power requirement of EVs depends on the traction power, which mostly depends on the weight of the EVs. The power loss of EVs is 5%–15% for manual transmission due to gear shifting from the first to the fifth gear, 15%–20% for automatic transmission (AT) due to slow pressure development in the torque converter, and 15%–25% for CVT (Rahman et al., 2012). Sorniotti et al. (2011) examined the performance of EVs using single-speed transmission and two-speed transmission and found a significant advantage in adopting a two-speed transmission system over a single-speed transmission system.
The power of EVs is limited compared to that of an internal combustion engine, as it requires much time to refuel energy. Therefore, it is important to save the power of EVs by decreasing transmission weight and reducing transmission loss by eliminating the number of gear shifts. Moreover, manual transmission, AT, and CVT are bulky and unsuitable in the available space of EVs because their power train space is limited in order to maintain vehicle performance (Sorniotti et al., 2011; McKeegan, 2020). According to a report, it could benefit EVs and make them 5% energy efficient, but it caused much transmission power loss due to the slower motor response (Porsche, 2019). Tesla originally planned to put a two-speed gearbox in the original Roadster manufactured by the gear manufacturing company ZF (Germany).
According to a review of EV powertrains on the road, EVs can be equipped with epicyclic transmission, a five-speed manual gearbox (5-SMT), AT, or CVT. Energy usage and gear shifting are issues with the aforementioned transmission methods for EVs. Although a single-speed gearbox is lighter, it is not capable of developing enough torque for acceleration. As a result of transmission problems, a technological innovation to solve them should emerge (Berawi, 2021, Rahman et al., 2019).
This study aimed to present a two-speed fuzzy-controlled electromagnetic gearbox (EMA2SGB). This aim was achieved by (i) examining the vehicle’s dynamic torque requirement in traction and speed while cruising and (ii) analyzing the electromagnetic force equivalent to the gear shifting axial force. The gearbox was designed based on the outcome of the first sub-objective outcome, and the second sub-objective outcome was used to design the electromagnetic actuator (EMA) as the gear shifter.
The potential of AEM2-SGB is obvious in changing from the first to the second gear and from the second to the first gear because of the efficacy of the fuzzy controlling mechanism using sensors and magnets. The AEM-2SGB is a prospective gearbox for EVs owing to its weight reduction of 37%–66%, transmission loss reduction of 40%–90%, and battery life enhancement of 5%.
The authors are grateful to the Finance Division of the International Islamic University Malaysia for financing this project as a Flagship Project entitled “Electric Coaster Innovation” (Ref. IRF19-032-0032).
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