Speaking of electric cars, you may associate it with the electric toy cars that you used to play with when you were young. After all, they all use the battery as a power source to drive the motor to drive it. This is true, but not entirely true. All electric toy cars use DC motors, so as long as two AA batteries can be used to drive the motor and let it drive the four wheels to rotate, but new energy electric vehicles are different.
Due to the need to drive a huge body, a high-power, high-voltage motor must be selected. In addition, although the DC motor is simple to control and the cost is low, the volume is too large, and the internal carbon brushes and commutators need to be regularly maintained and replaced, so the new energy electric vehicles are selected for higher efficiency, longer life and better safety. of the AC motor. From the name alone, it can be seen that the biggest difference between the two is the different current forms used.
Anyone who knows this aspect knows that the electricity in the battery is stored in the form of direct current (DC), and the motor of the electric vehicle uses alternating current (AC), so how to make the direct current in the battery become us? What about AC power needed? At this time, you need to use something called an "inverter".
We all know that the core technology of new energy vehicles is "three electrics", and the inverter is part of the electric drive system. Inverter is a device that converts direct current to alternating current (DC-AC), which is mainly composed of inverter bridge, control logic and filter circuit. The control circuit controls the operation of the entire system, the inverter bridge realizes the function of converting direct current to alternating current, and the filter circuit is used to filter out unwanted signals.
The magic of the inverter is that after receiving the driving control command from the vehicle controller, it can convert the DC power in the battery into the three-phase AC power required by the motor during the driving process. At the same time, the electric vehicle inverter will intelligently adjust the amplitude and Frequency, the frequency controls the speed of the electric car, and the amplitude controls the power of the car.
In the braking process of new energy vehicles, it can also play a role in recovering electric energy. Its performance is directly related to the power output performance of the motor and the battery life of new energy vehicles. It is one of the core parts of new energy vehicles.
To realize the conversion of current, the most critical part is the power semiconductor device, and its production process is very strict. Previously, Tesla recalled nearly 130,000 Model 3s because of the subtle differences in the production of power semiconductor devices. The commonly used power semiconductor device is "IGBT", which is called the CPU of the inverter.
IGBT (Insulated Gate Bipolar Transistor), also known as Insulated Gate Bipolar Transistor, is a composite fully-controlled voltage-driven power semiconductor device composed of BJT (Bipolar Transistor) and MOS (Insulated Gate Field Effect Transistor). With the advantages of high input impedance of MOSFET and low on-voltage drop of GTR, IGBT can realize the conversion between direct current and alternating current or change the frequency of current. It is mainly used in inverters, frequency converters and other products, and its performance directly determines the energy efficiency of the vehicle.
In order to meet the application requirements of high power density and high reliability, IGBTs are still developing in the direction of low power consumption, improved temperature characteristics, extended safe working area, and low cost. In the future, new materials, new chip processes and new packaging processes will be developed. breakthroughs in other aspects.
