Electric Vehicle (EV) Drivetrain Alternatives Based on Drivetrain Configuration
There are many possible EV configurations due the variations in electric propulsion and energy sources. Based on these variations, six alternatives are possible as shown in Figure 3. These six alternatives are
- • In Figure 3a a single EM configuration with gearbox (GB) and a clutch is shown. It consists of an EM, a clutch (C), a gearbox, and a differential (D). The clutch enables the connection or disconnection of power flow from EM to the wheels. The gear consists of a set of gears with different gear ratios. With the use of clutch and gearbox, the driver can shift the gear ratios and hence the torque going to the wheels can be changed. The wheels have high torque low speed in the lower gears and high-speed low torque in the higher gears.
• In Figure 3b a single EM configuration without the gearbox and the clutch is shown. The advantage of this configuration is that the weight of the transmission is reduced. However, this configuration demands a more complex control of the EM to provide the necessary torque to the wheels.
• Figure 3c shows a configuration of EV using one EM. It is a transverse front EM front wheel drive configuration. It has a fixed gearing and differential and they are integrated into a single assembly.
• In Figure 3d a dual motor configuration is shown. In this configuration the differential action of an EV when cornering can be electronically provided by two electric motors.
• In order to shorten the mechanical transmission path from the EM to the driving wheel, the EM can be placed inside a wheel. This configuration is called in-wheel drive. Figure 3e shows this configuration in which fixed planetary gearing is employed to reduce the motor speed to the desired wheel speed.
• In Figure 3f an EV configuration without any mechanical gearing is shown. By fully abandoning any mechanical gearing, the in-wheel drive can be realized by installing a low speed outer-rotor electric motor inside a wheel.
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Figure 3a: EV configuration with clutch, gearbox and differential |
Figure 3b: EV configuration without clutch and gearbox |
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Figure 3c: EV configuration with clutch, gearbox and differential |
Figure 3d: EV configuration with two EM |
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Figure 3e: EV configuration with in wheel motor and mechanical gear |
Figure 3f: EV configuration with in wheel motor and no mechanical gear |
C: Clutch |
GB: Gearbox |
