马达s are the most essential part of anyElectric Vehicle(EV)。这些负责利用存储在细胞中的化学能并将其转换为旋转能，从而驱动车轮并引起车辆的运动，因此这些电动机也称为牵引电动机。

In this article, we will be reading aboutdifferent types of traction motors used in Electric Vehiclesand learn about theircharacteristics。We will be comparing the characteristics and see which traction motor you need to use in your next Electric Vehicle.

Features of a Best Traction Motor

电动汽车电机的最重要功能是efficiency，，，，扭矩，，，，成本，，，，power to weight ratio,and reliability。电动汽车电动机和电动机控制器的效率对车辆的重量有直接影响，因为必须通过更大的电池来补偿损失的功率，这将影响车辆的总重量。因此，可以公平地说，EV的总体性能和效率主要取决于所使用的运动驱动器的类型。因此，必须比较扭矩速度特性和功率速度特性，以便选择最佳的牵引力。

Types of Motors used in EVs

马达technology has come a long way since the firstDC motor，，，，the refinement in power electronics has also paved the way for more efficient and more powerful motors. EVs use various types of motors depending on their propulsion system. Motors can be categorized based on the type of current required such asDC motors and AC motors。Furthermore, the motors can be classified based on the type of their construction or if permanent magnets are present or not. Some common types of motors used in EVs areBLDC电机，，，，永久磁铁同步电动机（PMSM），，，，Induction motor（（IM),Switched Reluctance马达（（SRM),Synchronous Reluctance motor，，，，etc.

DC系列电动机

DC系列电动机，也称为brushed DC motor是最基本的电动机类型，自1900年代以来已被广泛使用。当电流通过其在固定磁场中排列的线圈时，电动机起作用。该电动机易于控制，并且具有较高的初始扭矩能力，使该电动机成为一个不错的选择。它使用刷子和换向器进行工作。通过确保电流的方向可以控制电动机的旋转。但是主要的缺点是，刷子往往会磨损，需要定期维护。

The characteristics of the DC series motor is shown below:

在个人电动汽车（例如踏板车或汽车）中，由于其效率低，尺寸笨重以及需要频繁维护，因此不受拉丝直流电动机的优先选择。但是在需要高扭矩和负载功能的应用中仍然很受欢迎。因此，tDC系列电动机广泛用于印度铁路机车，起重机，重型设备等。

Advantages of DC Series Motor

• Very high starting torque
• 易于控制
• 高负载能力

Disadvantages of DC Series Motor

• Low efficiency
• Bulky in size
• Requires frequent maintenance

Application of DC Series Motor

印度铁路机车，起重机，重型建筑设备等。

BLDC电机

Brushless Direct Current Motors (BLDC) isalso known aselectronically commutated motor。These motors are one of the most common motors used in the电动汽车行业。BLDC电机s do not have brushes and therefore require very low maintenance compared to the DC motors, but unlike the brushed DC motor which has a simple operation, driving a BLDC motor requires complex motor controllers.

与其他具有相同功率评级和较高效率的电动机相比，由于诸如低转子惯性，紧凑型结构等益处，这些应用程序被广泛用于多种应用。BLDC电动机的损失较低，因为它们在转子中使用了永久磁铁，并提供了更快的反应，使其非常适合EV应用，尤其是对于2 Wheleers。

BLDC电动机的扭矩速度曲线如下：

From the above torque-speed curve, it is clear that the torque of the motor decreases linearly with the increase in speed. The motor has a very high starting torque but provides a low torque at a higher speed.

BLDC电动机的类型

根据它们的构造和设计，BLDC电动机有两种类型：内转子设计或轮毂电机和外转子设计或BLDC Outrunner Motor。The basic architecture of inner rotor and outer rotor brushless motors differs significantly. As we know that the magnets are used to spin all brushed and brushless motors. The rotor is the component that spins and holds the magnets while the stator's job is to produce a charge that repels or attracts the magnets, causing the motor to spin.定子位于外部，转子在轮毂电机的内部，而外转子的排列完全相反。下图显示了轮毂电机和轮毂电动机的组件。

Advantagesof BLDC Motor

• 不需要刷子。
• higher torque compared to other motors at the same current and voltage.
• 极高的功率密度。
• 极其效率。

BLDC电机的缺点

• Low torque at higher RPM
• 需要外部电机控制器
• Expensive

Induction Motors

感应电动机（IM）也被称为异步电机。基本上有2种类型IM，，，，a single-phase induction motor and a three-phase induction motor. Single-phase induction motors (SPIMs) are still not widely used in vehicles due to their problematic starting, low-speed operation complexity, and other control disadvantages. Hence only the 3 phase IMs are used. These motors are called induction motors because the electric current in the rotor required to create torque is acquired by electromagnetic induction from the stator winding's revolving magnetic field. There are 2 types of induction motor based on the type of its rotor. An induction motor's rotor can be either a squirrel cage rotor or a wound-type rotor. The IM runs at a speed slower than their synchronous speed, hence, the induction motors are also known as asynchronous motors. The Induction motors are preferred because of their simple design, great dependability, robustness, ease of maintenance, low cost, and ability to operate in a variety of environmental situations. In case of inverter failures, IMs may naturally de-excite, which is a significant safety benefit for EVs. IMs' field-oriented vector control is standardized in the industry.

与P相比，IM电动机的主要缺点包括效率较低Ermanentmagnet(PM)电动机或BLDC电动机，更大的功率损耗（由于笼子损失）和功率因数较差。在恒定功率操作区域中，可以使用磁通量的削弱来增加速度范围。一些车辆利用双逆变器技术作为双逆变器也可以用来扩展该区域。

The below image shows the torque-speed characteristics of an Induction motor.

感应电动机要求逆变器将存储在电池中的能量转换为交流电源，Tesla Model 3逆变器的图片如下：

The inverter is mounted in the motor housing of a 3 phase induction motor. The belowpicture of the induction motor is taken from theYoutube 视频by Weber State University.

Advantages of Induction Motor

• Very high efficiency
• 简单设计
• Robustness and can be used in harsh environment
• 需要低维护
• Low-cost motors

Disadvantages of Induction Motor

• lower efficiency compared to PM motors or BLDC motors
• Higher power losses

Application of Induction Motor

Used in Tesla Model S and Tesla Model X

永久磁铁同步电动机（PMSM）

As the name suggests, PMSM is an AC motor that uses a permanent magnet in its construction. It isa hybrid of a brushless DC motor and an induction motor.无刷的永久磁铁同步电动机（PMSM）提供高水平的可靠性和效率。它们还具有比交流感应电动机更大的扭矩，较低的框架尺寸，并且没有转子电流，所有这些电动机都比交流电动机（AICMS）受益。由于没有分配给磁场的定子功率，因此它的功率密度比具有相似评级的感应电动机更好。所以，the main benefit of a PMSM is that it can help you in reducing the size of your design without sacrificing torque, thanks to its excellent power-to-size ratio. PMSMs are commutated similarly to BLDC motors, however, the waveforms used need to be sinusoidal due to the structure of the windings.

PMSM采用矢量控制方法来达到此水平。面向场的控制（FOC）是一个用于描述向量控制方法的术语。向量控制技术通过将定子电流分解为两个部分：磁场发生器和扭矩发生器。分解后，两个组件都可以独立控制。

PMSM的速度扭矩曲线如下：

From the above graph, it can be inferred that the BLDC motors have a constant torque at a lower speed while it has a constant power region.

PMSM的优点

• It provides greater efficiency at high speeds
• It is far easier to maintain and install than an induction motor.
• It is capable of retaining full torque at low speeds.
• It provides smooth torque and dynamic performance

Disadvantage of PMSM

• Difficult to control
• Higher cost

Application

• Used in Nissan leaf

Switched Reluctance Motor (SRM)

开关的不情愿电动机通过改变其磁性不情愿而产生扭矩。它具有与无刷直流电动机的定子相似的显着杆和绕组，但是转子是由切成无磁铁或绕组的显着杆的钢制成的。与普通拉丝直流电动机不同，电源是将电源发送到定子绕组而不是转子。当定子和转子产生的磁场变化时，SRM通过定子中的交替电流函数。开关不情愿的电动机所含的转子杆少于定子杆，以避免转子和定子杆一起匹配时避免情况，并且不会产生扭矩。

Because of its control flexibility, simple structure, low cost, and great efficiency, a switching reluctance motor has several advantages over other types of electric motors. Due to the absence of a permanent magnet or winding in its rotor, an SRM is suitable for extremely高速应用程序和能维持高ratures。It also results in a durable and simple construction as well as a low manufacturing cost. Similarly, if a failure develops in any one winding or phase, the motor can still operate, but at a lower load. The biggest problem with SRM is its non-linear properties due to magnetic saturation, making precise torque control difficult.

下图显示了开关不情愿电动机的速度扭矩曲线。

From the above image, we can see that the SRM has a constant torque and constant power mode similar to PMSM but unlike PMSM where the torque declines to zero instantly after reaching the threshold, the SRM has a gradual decline even at higher speed.

Advantages of SRM

• Cheaper than other motors
• Simple to design and repair
• 与PMSM或BLDC电动机相比，SRM电动机可以在更严格的条件下运行。

SRM的缺点

• 控制扭矩很困难
• 高噪音
• High level of vibration.

SRM的应用

本田思域混合动力汽车

Conclusion

有不同类型的汽车可以在the market, each of the motors have their own advantages and disadvantage. The Brushed DC motor provides simple control and high initial torque but has lower efficiency and requires regular maintenance. The BLDC motor is extremely efficient and is also available in a hub-type enclosure which can be directly used inside a wheel reducing the additional cost and weight of the mechanical transmission, but the control mechanism of a BLDC is very complex. The Induction motor is a low-cost motor with high reliability and robustness but it is similar to a BLDC motor, it also requires an inverter as it is an AC motor. Furthermore, it has a lower efficiency than the BLDC motor. Then we have PMSM which is a cross between a BLDC and an IM. PMSM provides high torque and has a very high power to weight ratio but requires a very complex control method to drive the motor. There is Switched Reluctance Motor which is capable of working in harsh environments and is simple to design while being cost-effective but its non-linear characteristics make precise torque control challenging. So, we can say that there is not a one-fit solution for all the applications. All the motors have their own use cases and selection of motor can only be done after careful consideration of the application and its requirement. I hope that you enjoyed reading the article and if you have any questions, please feel free to comment down below.