The Difference Between DC Brush Motor and Brushless Motor
All motors are composed of a stator and a rotor. In order to make the rotor rotate, the direction of the current needs to be constantly changed, otherwise the rotor can only make a half turn. DC motor needs a commutator. Generally speaking, DC motors include brush motors and brushless motors. Brushed motors are called DC motors or carbon brush motors, DC motor refers to DC brushed motor, which uses mechanical commutation. The outer magnetic pole does not move, the inner coil moves, the commutator and the rotor coil rotate together, and the brushes and magnets do not move, so the commutator rubs and rubs to complete the switching of the current direction.
Brushless motor is also called DC variable frequency motor (BLDC) in some fields. It uses motor commutator, and the coil (armature) does not move the magnetic pole. At this time, the permanent magnet can be outside the coil or inside the coil. A single brushless motor is not a complete power system, and the brushless motor must pass the controller to achieve continuous operation. It is the brushless electronic governor that really determines its performance.
There are two types of brushless motor drives, one is square wave and the other is sine wave. Sometimes the former is called a DC brushless motor, the latter is called an AC servo motor. Brushless motors have different operating modes and can be divided into inner rotor brushless motors and outer rotor brushless motors. The inner rotor is all three-phase and the price is more expensive. The outer rotor is usually single-phase, and the price is lower. The mass production is close to the carbon brush motor, so it has been widely used in recent years.
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As one of the core parts of new energy vehicles, the electric drive system has an important impact on the performance of new energy vehicles, and has important significance for the power, economy, comfort, safety, reliability, and durability of new energy vehicles. In addition, in terms of industry needs, low cost, miniaturization, and intelligence are the main trends. The electric drive system of an electric vehicle is mainly composed of four parts: drive motor, transmission, power converter and controller. The drive motor is the core of the electric drive system, and its performance and efficiency directly affect the performance of electric vehicles. The size and weight of the drive motor and transmission will also affect the overall efficiency of the vehicle. Power converters and controllers can help electric vehicles operate safely and reliably.
In the long term, the trend of flat wire motors is highly certain. In the first half of 2021, the penetration rate of flat wire motors among the top 15 vehicle models in terms of sales reached 28%, compared to just 14% in 2020. It is anticipated that by 2025, the proportion of flat wire motors in the drive systems of new energy vehicles will exceed 80%.
X-Pin motor technology allows for a reduction in the height of the linear segment at the end of the motor while maintaining a high slot fill factor. This results in a shorter overall motor length, saving copper wire usage and improving motor efficiency, thus achieving miniaturization.
In recent years, the market penetration of new energy passenger vehicles has continued to rise. Due to the high demand, existing cylindrical-wire motors have become insufficient in meeting the performance requirements of electric vehicle propulsion. Therefore, the substitution of flat-wire motors for cylindrical-wire motors is a highly certain trend for the future. Motor manufacturers are actively seeking high-capacity, high-quality production processes to meet market demands, with ongoing optimization and innovation in the manufacturing processes of flat-wire motor stators.
As is well known, the energy conversion efficiency of electric motors is around 90%, meaning that losses account for approximately 10%. Within the energy losses of a motor, copper loss, which is the heat generated by the current passing through the stator winding, constitutes about two-thirds of these losses.By adopting flat wire motors, the round wire windings are replaced with flat wire windings, increasing the amount of copper per unit area on the stator. This increases the copper fill factor to 20% to 30%, meaning more copper is packed into the stator slots. This effectively reduces winding resistance, and the lower the resistance of the winding, the higher the electrical efficiency. Consequently, it reduces copper losses.