Current Status and Development Trends of Electric Vehicle Transmissions
Author:
Release Time:
2025-07-12
Traditional transmissions, as speed-changing devices that coordinate engine speed and actual vehicle speed, are used to maximize engine performance. Specifically, because the reasonable speed range of an engine is narrow (generally around 1000-4000rpm ), it cannot output torque at too low a speed, and it will be in an inefficient working state once the engine speed is too high. Therefore, when driving, fuel vehicles need to adjust the reduction ratio by shifting gears so that the speed remains in a reasonable working range. For fuel vehicles, without a transmission, the vehicle cannot drive normally.
Electric vehicles are not without transmissions; the reducer can be understood as a single-speed transmission, which is actually a type of transmission. Because the working range of the motor is wide (generally in 0-15000rpm ). It can output a large torque at low or even zero speed, and can output constant power at high speed. Therefore, the motor characteristics can basically match the vehicle's needs, without the need to add a multi-speed transmission, only a single-stage reducer or a two-speed transmission is needed.
Currently, most pure electric vehicles in China do not have a physical transmission. Many people may see the gear lever in some cars and see gear displays on the instrument panel, but in fact, those are simulated gears to cater to consumers. The motor itself does not need the assistance of a gear transmission mechanism to work stably at various speeds. In addition, pure electric vehicles cannot be equipped with ordinary transmissions. The main reason is that the size and weight of ordinary transmissions are too large for electric vehicles. The battery pack takes up the entire chassis space, and there is no excessive space for installation; secondly, the transmission efficiency is not high enough. At the same time, considering the weight factor of the transmission, it may also reduce the actual driving range.
In view of the above, most pure electric vehicles on the market are single-speed transmissions. The advantages are: low cost, simple structure, easy installation, low failure rate, low power loss, and small size. The disadvantage is: when the speed of the electric vehicle reaches its limit, there is no room for improvement, so the speed of the electric vehicle is restricted, and a single transmission ratio usually cannot take into account both the power and economy of the pure electric vehicle.
Multi-gear: The existing motor characteristics are difficult to meet the vehicle's power and economy needs under all working conditions. Installing a multi-speed transmission can effectively adjust the motor's output performance.
High speed: By increasing the working speed of the motor and adopting appropriate transmission systems and control strategies, the allowable range of regenerative braking can be widened, so as to adapt to more working conditions, make the vehicle more energy-efficient, and improve the driving range. Currently, the maximum speed of drive motors of many OEMs has reached 14000rpm or more. With the development of high-speed drive motors, the high speed of electric vehicle transmissions will also become a trend.
Modularization: Integrating the motor, transmission, and controller makes the vehicle structure more compact, the performance more excellent, and facilitates control and reduces costs. The integrated design and management control of modular electromechanical coupling transmission systems is the development direction of electric vehicle powertrain systems.
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