500kwh battery for energy storage.Detailed analysis of electric vehicle motors and electronic control technology

　　The batteries of electric vehicles are discussed more, but equally important are the motors and electronic controls. What is the domestic technical level? At this stage, most of the discussions on key components of electric vehicles focus on power batteries, while there is very little discussion on motor electronic control and other aspects. The reason is that, on the one hand, regarding the development of power battery technology, new technologies and hot topics emerge from time to time, which can easily attract the attention of the media and readers. In terms of motor and electronic control, there are very few new hot spots in new technologies; secondly, in the field of motor and electronic control, especially in the field of electronic control, domestic suppliers are still in a relatively preliminary stage, and the products they develop have not yet reached international standards. leading level, which also greatly limits consumers’ concern for motor electronic control technology. Analysis of Motor Technology The so-called motor, as its name suggests, is a power component that converts electrical energy into mechanical energy. When electrical energy is converted into mechanical energy, the motor exhibits the operating characteristics of a motor; when electrical energy is converted into mechanical energy, the motor exhibits the operating characteristics of a generator. When most electric vehicles are braking, mechanical energy is converted into electrical energy, which is used to recharge the battery through a generator. The motor is mainly composed of a rotor, stator winding, speed sensor, housing, cooling and other components. In the field of new energy vehicles, permanent magnet synchronous motors are widely used. The so-called permanent magnet refers to the addition of permanent magnets when manufacturing the motor rotor to further improve the performance of the motor. The so-called synchronization means that the rotation speed of the rotor and the current frequency of the stator winding are always consistent. Therefore, by controlling the input current frequency of the motor's stator winding, the speed of the electric vehicle will eventually be controlled. How to adjust the current frequency is a problem that the electronic control part must solve. Compared with other types of motors, the biggest advantage of permanent magnet synchronous motors is that they have higher power density and torque density. To put it bluntly, compared with other types of motors, under the same mass and volume, permanent magnet synchronous motors It can provide maximum power output and acceleration for new energy vehicles. This is also the main reason why permanent magnet synchronous motors are the first choice for most automobile manufacturers in the new energy automobile industry, which has extremely high requirements for space and weight. In addition to permanent magnet synchronous motors, asynchronous motors have also received widespread attention due to their use by Tesla. Compared with synchronous motors, the speed of the motor rotor is always smaller than the speed of the rotating magnetic field (generated by the stator winding current). Therefore, the rotor always seems to be "inconsistent" with the current frequency of the stator winding, which is why it is called an asynchronous motor. Compared with permanent magnet synchronous motors, the advantages of asynchronous motors are low cost and simple process; of course, its disadvantage is that its power density and torque density are lower than those of permanent magnet synchronous motors. As for why Tesla Model S uses asynchronous motors instead of permanent magnet synchronous motors, in addition to controlling costs, it is also very important that the larger Model S body has enough space to accommodate a relatively larger asynchronous motor. factor. In addition to synchronous motors and asynchronous motors, wheel hub motors are also a hot spot in new energy vehicle motor applications. The biggest feature of the wheel hub motor is that the vehicle's power device, transmission device and braking device are all integrated into the wheel hub. Compared with traditional power devices, the advantages of in-wheel motors are obvious. Since a large number of transmission parts are saved, the vehicle structure is relatively simple; of course, there are still many problems to be solved with in-wheel motors in terms of motor synchronization control, water sealing, etc. solve. Analysis of electronic control technology The electronic control unit is equivalent to the ECU of a traditional car and is the main execution unit for controlling high-voltage components in electric vehicles. In addition to motor control, the control of vehicle chargers, DC-DC units and other related components is also implemented by electronic control units. The core of the electronic control unit is the control of the drive motor. The power battery, the provider of the power unit, provides direct current, while what is needed to drive the motor is three-phase alternating current. Therefore, what the electronic control unit wants to achieve is a process called inversion in power electronics technology, that is, converting the DC power at the power battery end into the AC power at the input side of the motor. Common control strategies for modern motors include SVPWM (space vector pulse width modulation technology), DTC (direct torque control technology), speed sensorless control and various novel intelligent control technologies. Many experts and scholars are also working on improving motor control, improving motor stability, and enhancing motor anti-interference capabilities. In order to realize the inversion process, the electronic control unit requires components such as DC bus capacitors and IGBTs to work together. When the current is output from the power battery terminal, it first needs to pass through the DC bus capacitor to eliminate the harmonic components. Then, by controlling the switch of the IGBT and the cooperation of other control units, the DC power is finally inverted into AC power, and finally used as the power source of the power motor. Input Current. As mentioned above, by controlling the frequency of the three-phase input current of the power motor and cooperating with the feedback values of the speed sensor and temperature sensor on the power motor, the electronic control unit finally controls the motor. In addition to controlling the motor, the electronic control unit is also the main control mechanism for components such as on-board chargers and DC-DC units. Charging is just the opposite of motor control. It requires converting the alternating current provided by the power grid into the direct current of the power battery, which is a process called rectification in power electronics. The DC-DC unit implements the process of charging the 12V battery through the power battery. The electronic control unit needs to convert the high voltage at the power battery end into the low voltage end of the 12V battery to ultimately charge the new energy vehicle. Summary: As an important field of new energy applications in the future, electric vehicles are still a lot of technologies that are not mature enough, but this is a new idea for future development. Motor control in electric vehicles will also be a key link restricting their revolutionary innovation.

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