Electric drive, also known as electric drive axle powertrain, is essentially a combination of motor and gears. Its main function is to convert high-voltage electrical energy into driving force, thereby driving the wheels to enable the vehicle to move.

Electric drive, also known as electric drive axle powertrain, is essentially a combination of motor and gears. Its main function is to convert high-voltage electrical energy into driving force, thereby driving the wheels to enable the vehicle to move.
The electric drive consists of components such as the motor, inverter, and gearbox assembly. The gearbox assembly includes parts like the gearbox housing, oil pan, gearbox cover, oil baffle, oil filter, electronic oil pump, gears, and output shaft. The inverter is responsible for converting the high-voltage direct current released by the battery pack into three-phase alternating current for the motor. After the motor rotates and generates power, this power is transmitted to the gearbox, converted, and then delivered to the wheels through the output shaft. At the same time, the gearbox also requires lubrication and cooling.
Each electric vehicle is equipped with at least one drive assembly, usually installed at the rear of the vehicle, responsible for driving the rear wheels. This configuration is known as a single motor version. Higher-end models may be equipped with two drive assemblies, located at the front and rear of the vehicle, forming a dual motor version.
The rear drive assembly is compatible with the rear axle, allowing it to directly transmit power to the rear wheels. It usually also integrates a parking mechanism that locks the drive assembly when in the P gear. Some off-road models may also add a differential lock to the rear drive assembly. The front drive assembly is compatible with the front axle, transmitting power to the front wheels, but the front drive powertrain typically does not come with a parking mechanism. The main task of the inverter is to convert the high-voltage direct current released by the battery pack into the three-phase alternating current required by the motor and to deliver it precisely to the motor stator. The motor stator generates a magnetic field through hundreds of stator windings, interacting with the magnetic field of the motor rotor to produce torque and output power. The gear assembly acts like a transmission, responsible for converting the power input from the motor and delivering it to the axle. The electric drive housing serves the function of mounting all electric drive components, similar to an engine block. The reason for needing gears instead of having the motor drive the wheels directly is that the torque output directly from the motor is relatively small and cannot meet the overall vehicle's needs, thus requiring gears to reduce speed and increase torque.
Its advantages include flexible and varied design, small axle span, simple design and manufacturing, and the ability to achieve high gear ratios, making it very suitable for large vehicles. However, its disadvantages are also evident, such as larger dimensions, difficulty in platforming, and challenges in achieving commonality.
The advantages of this design include compact size, simple design and manufacturing, lightweight, and due to the overall smaller size, it is very suitable for small vehicles. Its disadvantages include limited gear transmission ratio due to concentric shafts, difficulty in oil entering the motor air gap, and the overall length affecting axle layout.
The advantages of this design lie in its minimal size, strong load-bearing capacity, and its facilitation of platforming and shared design. However, its disadvantages are also quite apparent, such as limited gear transmission ratio, difficulty in oil entering the motor air gap, complicated manufacturing processes, and excessive overall length. These issues may lead to difficulties in axle layout. Regardless of the layout method used, the final effect depends on the efficiency of the motor. The efficiency of the motor is influenced by rotational losses and torque losses. These factors are crucial for the motor and are key in deciding which type of motor to choose. To reduce rotational losses, it is advisable to avoid using preloaded bearings, such as tapered roller bearings, as larger bearing diameters lead to greater rotational losses. In contrast, deep groove ball bearings are more commonly used in electric drives. When the motor load is very high or used in large vehicles, tapered roller bearings should be prioritized.