In this era when new energy vehicles are gradually emerging, the importance of drive motors to new energy vehicles is no less important than that of engines to fuel vehicles, because it not only determines how fast the vehicle starts, but also determines the acceleration performance of the vehicle. Because of this, many car manufacturers are now paying great attention to the research and development of motors, which is the new favorite of the majority of car companies.
Currently, there are two main types of vehicle motors that can be promoted and used in the field of new energy. They are permanent magnet synchronous motors and AC asynchronous motors. Among them, the former is quite popular among domestic new energy car companies and has many applications, while the latter is not so lucky. Not to mention domestic users, even the global users are also very few.
So, why can the permanent magnet synchronous motor win the favor of so many new energy and traditional car companies? What is the difference between a permanent magnet synchronous motor and an AC motor? Why don't Tesla and NIO use permanent magnet synchronous motors? Let the professor continue! What is the difference between
permanent magnet synchronous motor and AC asynchronous motor?
1. Different structure settings
From the structural level, the structure of the permanent magnet synchronous motor is more complicated than that of the AC asynchronous motor, and the cost output is higher. However, the permanent magnet synchronous motor has a smaller volume and a lighter weight.
The permanent magnet synchronous motor is mainly composed of a rotor, an end cover and a stator. Its stator structure is very similar to that of an ordinary induction motor. However, its rotor structure design is very unique, with high-quality permanent magnet poles placed on the rotor. Electricity can generate a rotating magnetic field.
As for the structure of the asynchronous motor, it can be divided into two parts: the stator and the rotor. Of course, in addition to these there are end covers, fans and other auxiliary parts. It is worth noting that because the stator of the asynchronous motor generates an exciting rotating magnetic field and absorbs electric energy from the power supply, its stator is an armature.
2. Working principle is different.
working principle level, permanent magnet synchronous motor is excited by permanent magnet to generate synchronous rotating magnetic field, three-phase stator winding reacts through armature under the action of rotating magnetic field to induce three-phase symmetrical current. At this time, rotor kinetic energy is transformed For electrical energy, the permanent magnet synchronous motor is used as a generator;
Conversely, when three-phase symmetrical current is applied to the stator side, because the three-phase stator has a difference of 120 degrees in space, the three-phase stator current generates a rotating magnetic field in the space and the rotor rotates The magnetic field moves under the influence of electromagnetic force and converts electrical energy into rotor kinetic energy. The permanent magnet synchronous motor is used as a motor.
AC asynchronous motor is a three-phase stator winding with a symmetrical alternating current to generate a rotating magnetic field to cut the rotor winding, thereby generating induced current in the rotor winding, and the current-carrying rotor conductor generates electromagnetic force under the action of the stator rotating magnetic field to act on the motor shaft. The electromagnetic torque drives the motor to rotate in the direction of the rotating magnetic field.
It is worth noting that when the conductor cuts the magnetic field lines in the magnetic field, an induced current will be generated inside the conductor, and then work hand in hand with the induced magnetic field to apply a driving force to the motor's rotor to drive the rotor to move.
Why is permanent magnet synchronous motor more popular than AC asynchronous motor?
According to the characteristics of permanent magnet synchronous motors and AC asynchronous motors, permanent magnet synchronous motors are more suitable for frequent start and stop working conditions, while AC asynchronous motors (induction motors) are more suitable for high-performance and high-speed working conditions. Why do high-performance electric vehicles such as Tesla and Weilai use AC asynchronous motors?
From the characteristics listed in the table, the reason why the permanent magnet synchronous motor can be favored by most car companies seems to be very simple. It is nothing more than the similar technology.Under the technical level, the torque density, power density, and efficiency of permanent magnet synchronous motors are better than AC asynchronous motors, which is of great benefit to improving the energy efficiency of vehicles and extending the cruising range.
But then again, although AC asynchronous motors do not have advantages in terms of weight and volume, they have a wide range of speeds, low manufacturing costs, and simple processes. The operation is not easy to cause the motor to lose magnetization, which is reliable, stable and durable. The point is a bright spot that permanent magnet synchronous motors do not have.
On the other side, the permanent magnet synchronous motor can still guarantee an energy conversion efficiency of about 95% in an instant state, and because the motor is small in size, light in weight and does not require a high-efficiency and complex cooling system, it can effectively and maximize the use of the vehicle The spatial layout of the vehicle plays a very important role in the design and manufacture of the vehicle.
Secondly, because the core technology of motors is basically monopolized, the motors used by many domestic car companies are provided by suppliers, and the only car companies that can independently own the independent property rights of motors are only BYD, Roewe, Weilai, and Tesi. Pull these few, even if the number is described as few stars.
Of course, in addition to technical characteristics and market reasons, the raw materials used in the two motors cannot be ignored. It should be known that permanent magnet materials such as neodymium iron boron used in permanent magnet synchronous motors belong to important rare earth resources, while rare earth resources are very scarce in Europe and the United States. On the other hand, China has 70% of the world’s rare earth resources. The total output accounts for 80% of the world's total.
is the two most popular drive motors used by current car companies. There is no difference between permanent magnet synchronous motors and AC asynchronous motors, but they are different in what they are good at. For car companies, different considerations are often taken into consideration, and naturally the selected motor objects are different.
From another perspective, which design scheme or type of components should be selected for the design of an electric vehicle drive system is not based on the merits of individual components to make decisions, but through a combination of battery management systems and electronic control Make decisions after analyzing and considering multiple levels of system and vehicle layout design.
