The first bottleneck in the development of electric vehicles is the power battery, and the second bottleneck is the electric motor controller. In the past, the power supply of trolleybuses was provided online by the sliding net. The DC motor used has been used to drive the car, and later it was changed to an AC motor. At present, electric vehicles are used in AC motors. The power is provided by the car battery, and the battery can only supply DC power to the vehicle. The battery supplies DC power, which in turn requires AC power. In other words, the direct current must be changed to alternating current to drive the AC motor. Electric vehicles are becoming more and more popular, and more and more people are asking for more knowledge. The following is an introduction to the principle and technical development trend of electric motor controllers. Electricity is a natural phenomenon, which refers to the phenomenon caused by electron motion, which is a physical phenomenon caused by static or moving charges. Current refers to the directional movement of charged particles. Industrial electricity refers to current, and the current always flows to the negative pole at the load end. This is similar to the flow of water in nature, always flowing from a high point (positive) to a low (negative). Direct current means that the current flows in the conductor does not change with time, and the alternating current flows in the conductor alternates with time. The industrial direct current expresses a straight line on the time axis, that is, the change frequency is 0. The industrial alternating current exhibits a sine wave change on the time axis. In China, the sine wave changes frequency is 50 Hz, that is, the 1 second sine wave changes 50 times. .