Check the relationship between automotive motors and complete vehicles
The electric motor uses a coiled coil to generate a rotating magnetic field and acts on the rotor to form a magnetoelectric power rotating torque. The electric motor is divided into a direct current motor and an alternating current motor according to the power source used. The electric motor in the electric power system is mostly an alternating current motor, which may be a synchronous motor or an asynchronous motor. . It is mainly composed of a stator and a rotor. The direction of the force-carrying wire in the magnetic field is related to the direction of the current and the direction of the magnetic induction line. The working principle is that the magnetic field acts on the current to force the motor to rotate.
The electric drive system consists of two parts: the motor and the motor controller. The motor belongs to the field of heavy assets. The motor controller belongs to the electronic field of light assets. The correlation between the two fields is very low. It is easy to manufacture separately. One of the development trends in the field of electric drive systems is industrial integration, and motor controller manufacturers and motor manufacturers cross each other. In the "Spring and Autumn Period" of the electric drive system, the company that can win the last time must have three aspects of "understanding the car, knowing the motor, and knowing the electronics". The three-part combination of the electric drive system is really suitable for the new energy car. Electric drive system.
In the market environment, the development trend of overseas electric vehicle motor electronic control industry is relatively clear. There are two main routes: one is the in-house route that the whole vehicle company represented by Toyota uses its own developed parts; the second is the whole Car manufacturers cooperate with powerful electronic control manufacturers to form a stable supply chain. Foreign new energy vehicles started early in all aspects, professional parts and components enterprises have obvious advantages in technology, and market concentration is high. Well-known parts companies such as Bosch, Continental, Magna, Hyundai Mobis and ZF Wait, monopolize most of the market share.
Several common motor starting methods include: full pressure direct start, auto-decompression start, y-delta start, soft starter, frequency converter.
Direct start at full pressure: In the case of full-voltage direct start in both grid capacity and load, full-voltage direct start can be considered. The advantages are convenient operation control, simple maintenance and economical. It is mainly used for the starting of small power motors. From the perspective of saving electric energy, this method should not be used for motors larger than 11kw.
Auto-coupling decompression start: The multi-tap decompression of the autotransformer can not only meet the needs of different load starting, but also get a larger starting torque. It is a kind of decompression that is often used to start a large capacity motor. Starting method. Its biggest advantage is that the starting torque is large. When its winding tap is at 80%, the starting torque can reach 64% of the direct starting. And the starting torque can be adjusted by tapping. It is still widely used today.
Y-δ start: For the squirrel-cage asynchronous motor whose normal running stator winding is delta-connected, if the stator winding is connected to a star at the start, and then connected to the triangle after the start, the starting current can be reduced. To mitigate its impact on the grid. Such a starting method is called a star-delta decompression starting, or simply a star-delta starting (y-delta starting).
When starting with the star-delta, the starting current is only 1/3 of the original starting directly by the delta connection. If the starting current at the time of direct start is 6 to 7 ies, the starting current is only 2 to 2.3 times at the start of the star-delta. This means that when starting with the star-delta, the starting torque is also reduced to 1/3 of the original starting directly by the delta connection. Suitable for applications with no load or light load start. And compared with any other decompression starter, its structure is the simplest and the cheapest. In addition, the star-delta starting method has the advantage that when the load is light, the motor can be operated in star connection. At this time, the rated torque can be matched with the load, which can improve the efficiency of the motor and save power consumption.
Soft starter: This is the use of the phase shift voltage regulation principle of the thyristor to achieve the voltage regulation start of the motor, mainly used for the start control of the motor, the starting effect is good but the cost is high. Due to the use of thyristor components, the thyristor has a large harmonic interference during operation and has a certain impact on the power grid. In addition, fluctuations in the power grid can also affect the conduction of the thyristor components, especially when there are multiple thyristor devices in the same power grid. Therefore, the failure rate of the thyristor component is high, and since the power electronics technology is involved, the requirements for the maintenance technician are also high.
Inverter: The frequency converter is the motor control device with the highest technical content, the most complete control function and the best control effect in the field of modern motor control. It adjusts the speed and torque of the motor by changing the frequency of the power grid. Because it involves power electronics technology and microcomputer technology, it is costly and has high requirements for maintenance technicians. Therefore, it is mainly used in areas where speed regulation is required and speed control is required.
About speed control method
There are many speed control methods for electric motors, which can adapt to the requirements of different production machinery speed changes. Generally, the output power of the motor will change with the speed when the speed is adjusted. From the perspective of energy consumption, the speed can be roughly divided into two types:
1 Keep the input power unchanged. By varying the energy consumption of the governor, the output power is adjusted to adjust the speed of the motor.
2 Control the motor input power to adjust the speed of the motor. Motor, motor, brake motor, variable frequency motor, speed control motor, three-phase asynchronous motor, high voltage motor, multi-speed motor, two-speed motor and explosion-proof motor.