Structure and strong points

The AC inductive motor (AC motor) is most commonly used for industrial purposes because it has a simple structure and is easy to maintain. The AC motor is actuated by the electromagnetic induction that occurs between the coils located in its rotor and stator. The stator is made up of a core and three phase coils that are located in the slots of the core. The core is made of silicon steel sheets that are laminated after the slots have been created. The rotor is made up of a core and coils as well.

There are two types of rotor coils, a winding type and a cage type. The winding rotor has three phase coils in its slots that are connected to three slip rings; this type of rotor coil can be excited by either an external circuit or a power source. The cage-type rotor has bars in its slots that are made from conductive material. These bars are connected each other of the core via end rings. This is what is referred to as a simple rotor coil structure. The smaller size motor for this type of structure often utilizes an aluminum die-casting cage as one body cast for these bars and the end rings. For electric vehicles, this aluminum die-cast cage-type AC motor is very common because it has a simple structure, is easy to maintain, and is also very durable.

Examples for EVs

Table 5.5 shows the specifications for AC motors and control units that have been adopted for use in electric passenger vehicles. The downsizing of motors for electric passenger vehicles through water cooling and high-speed control technology has been moving at an accelerating pace in recent years, and these motors often use only one fixed-ratio reduction gears. In addition, they sometimes use a compact drive unit that combines the final drive and differential gears in order to reduce total weight and volume.