The core components of the electric drive system are electronic components and electric motors. They are complex subsystems with different characteristics.
The electric motor is omnipotent and can output 93-97% of power in almost the entire speed range. It has the advantages of high reliability and light weight and etc.. Unlike an internal combustion engine, the motor achieves maximum torque at very low speeds, and in fact the maximum torque is available from the starting position. Therefore, the use of a single-speed transmission in a pure electric vehicle can meet the power output requirements.
Motors used by Audi as a drive system can be divided into two categories. One type is the asynchronous motor (ASM). They do not have permanent magnets, are simple in design, durable, low maintenance and long lasting. They are only used in applications that are integrated into the gearbox.
The second type is a permanent magnet synchronous motor (PSM). With higher power density, they are more compact and lighter in many application designs. In addition, high torque and efficiency are achieved in the lower speed range. The performance of the motor depends on its design, the power and torque can be adjusted by changing its diameter and length.
In hybrid vehicles such as the Audi Q5, Audi uses a permanent magnet synchronous motor designed to achieve higher torque. They are large in diameter but only a few centimeters in length, so they can be easily integrated between the internal combustion engine and the gearbox. The optimum speed range is between 500 and 5,000 rpm one minute, which intelligently coordinates the torque characteristics of the internal combustion engine.
For repetitive or permanent electric vehicles, power-optimized PSM and ASM motors are suitable for their high speed versions. They are smaller in diameter than torque optimized motors. On the other hand, they are longer and have a wider range of speeds.
All motors used in Audi are liquid-cooled to keep their reliable operating temperature as high as 180 °C. However, thermal factors limit its power potential, but short-term overload operation is allowed. For example, an electric motor in an A1e-tron electric vehicle can achieve a continuous operating power of 61 hp (45 kW) and an instantaneous peak power of 102 hp (75 kW) in a short period of time.
Highly complex: pulse controlled inverter
Electronic components are the most complex and expensive components of an electric drivetrain: a pulse-controlled inverter converts a DC voltage to an AC voltage as needed by the motor.
In the electronic component housing, complex internal forces are hidden: for example, in the Audi Q5, the pulse-controlled inverter must use a voltage of 264 volts to output up to 40 kW, as if continuously turning on and off and dimming 666 power in an instant for a 60 watt bulb. At its core is a module consisting of several interconnected semiconductor components, IGBT (Insulated Gate Bipolar Transistor).
The internal temperature of the electronic components is much higher than 100 °C. Relying on the liquid in the metal casing to cool the heat. The latest generation of pulse-controlled inverters used in the Audi Q5 is lightweight and extremely compact. Its volume does not exceed 6 liters. It has been integrated into a DC power converter that supplies a 12 volt electrical system in a high voltage system.