Whats a Motor

What is a Motor?

The term "motor" is commonly used to describe a power unit that produces motion, known as a "prime mover." On the other hand, an "electric motor" specifically denotes a prime mover powered by electricity.

Fig. 1.1 Input and output to and from a motor

An electric motor is a sophisticated and highly efficient device utilized for the conversion of electrical energy into mechanical energy. Its intricate design and precise engineering enable it to power a wide range of applications across various industries. Additionally, electric motors are essential in numerous everyday devices, from household appliances to industrial machinery. These motors can vary in size and power, catering to specific needs in different sectors. They play a crucial role in modern society, driving innovation and efficiency in many aspects of life. 

Scientifically speaking, the electric motor is a crucial device utilized to convert electric power into either motive energy or electrical energy into mechanical energy. If we refer to Fig. 1.1, we can observe a clear flow diagram illustrating this energy conversion process. The arrow in the diagram represents this transformation, with the left end symbolizing the electrical input and the right end indicating the mechanical output. To provide brevity, the terms "electrical input" can be shortened to just "input," and "mechanical output" or "motive energy" can be abbreviated to "output."

Electric motors are meticulously crafted to offer continuous rotation or linear movement over a considerable distance in proportion to their size. Their effectiveness and adaptability make them essential in a wide range of electronic gadgets and industrial settings.

Electric motors are usually designed to provide consistent rotation or linear motion, covering a considerable distance in proportion to their compact size. They play a crucial role in powering various devices and machinery across industries.

From a scientific viewpoint, an electric motor functions as a mechanism that transforms electric power into motive energy, or more accurately, electrical energy into mechanical energy. Figure 1.1 illustrates an energy flow chart. The beginning of the arrow signifies the electrical input, whereas the end symbolizes the mechanical output. To be concise, "electrical input" can be abridged to "input," and "mechanical output" or "motive energy" can be streamlined to "output."

In the realm of engineering, electric motors are meticulously designed and engineered to provide continuous rotation or linear movement over a significant distance relative to their size. These motors play a crucial role in various applications, showcasing their efficiency and versatility in powering a wide range of devices and machinery.

From a scientific perspective, an electric motor serves as a mechanism to convert electrical energy into kinetic energy, or more specifically, electrical potential into mechanical force. In Figure 1.1, there is a diagram illustrating the flow of energy. The start of the arrow represents the electrical input, while the end indicates the mechanical output. In short, "electrical input" can be shortened to "input," and "mechanical output" or "kinetic energy" can be simplified to "output."

Throughout the energy conversion process, a fraction of the initial input undergoes transformation into heat instead of being utilized as motive energy. This phenomenon, known as "loss," signifies an inherent inefficiency within the system. Notably, in Japan, a staggering 60% or more of the total generated power is directed towards powering various types of motors, underscoring the crucial role these devices play in energy consumption. In essence, this highlights the impact of energy losses and the importance of optimizing energy efficiency in industrial processes.

In the realm of environmental conservation, the development and execution of motors with reduced losses pose a significant hurdle. The reduction of these losses not only boosts energy efficiency but also plays a key role in sustainability endeavors by cutting down on energy usage and its related environmental repercussions.

The correlation between the input power, output (often known as motive energy), and losses is essential for grasping the efficiency of electric motors. Engineers can strategically enhance motor performance and reduce energy wastage by gaining a deep understanding of this correlation.

Input power = mechanical output + loss

Unit for those amounts is Watt [W].

Input power and mechanical output are defined by the following equations:

Input power [W] = Voltage [V] x Current [A]

Mechanical output [W] = Rotating speed [rad/s] x Rotative force [Nm]

(rad is called radian and Nm Newton meter)

Motor efficiency refers to the fraction of mechanical output to input power as a percentage (%).

Loss, in the context of the energy transformation mechanism in electric motors, is influenced by a variety of elements. Apart from mechanical occurrences such as friction, inefficiencies in the motor's parts are generally regarded as the main culprits of this loss. These inefficiencies encompass losses experienced in both the copper wire and the motor core.

Copper loss signifies the wastage of energy as heat because of the resistance faced by the electric current traveling through the copper wire windings. Conversely, iron loss is linked to energy dissipation in the core of the motor, typically triggered by magnetic hysteresis and eddy currents.

Understanding and mitigating these losses are crucial for optimizing motor efficiency and minimizing energy wastage, ultimately leading to more sustainable and environmentally friendly operations.

 

 Components of a Motor

Motor components are classified into five main portions (1) to (5) as Fig. 1.2 shows.

Fig. 1.2 Motor components

(1) Rotor

Rotating part

(2) Bearing

Supporting part of the rotating shaft of the rotor

(3) Stator

Part generating force used to rotate the rotor

(4) Bracket or end plate

Bearing supporting part integral for the stator

(5) Lead wire

Wire connected to the drive circuit supplying power to the motor or wire connected to the power supply

 

Stator

Of these components, the parts most closely related to the basic classification method for motors are the stator and the rotor. The following four types are listed as the typical stator structure:

A: Stator of distributed winding

B: Stator of concentrated winding

C: Inductor stator

D: Permanent magnet stator

 

Rotor

Rotors can be classified into 10 different types.

(1) Squirrel-cage rotor

(2) Salient-poled squirrel-cage rotor

(3) Semi-hard steel rotor

(4) Soft-steel rotor

(5) Salient-poled lamination rotor

(6) Soft-steel rotor with fine teeth

(7) Permanent-magnet rotor

(8) Inductor rotor

(9) Winding rotor

(10) Commutator rotor

In the following ,we will discuss how various types of motor are classified by combining the stator and the rotor

Motor-configuring material

The following is a brief explanation of principal materials in a motor:

(1) Wire

Wire, an essential component in electrical systems, acts as the pathway for electric current to flow, serving as a vital conductor. This conductor is commonly made of copper, although sometimes aluminum is used as well in certain applications.

Lead wire serves a dual purpose in connecting the power supply to the motor and participating in the internal winding process. This winding, known as magnet wire in English, plays a crucial role in generating the motor's magnetic field. Interestingly, in Japan, this particular winding is recognized as enameled wire because of the insulation provided by enamel resin.

While modern insulation materials frequently incorporate high-polymer substances, the conventional designation of enameled wire continues to endure. In Japanese terminology, the phrase "enameled wire" is employed, whereas in English, it is referred to as magnet wire.

(2) Core

The core, essential for guiding flux, is commonly made of iron, as its name suggests. Furthermore, a core employed to connect two magnets through flux is known as a yoke.

Iron employed in mechanical structures typically contains carbon (C) as an essential component. Conversely, iron utilized in cores is alloyed with silicon (Si), known as silicon steel. In the realm of motors, the core is segmented into the stator core and the rotor core. This division facilitates the creation of a magnetic circuit that is formed through the air gap present between these core components.

For motors that operate using direct current (DC), like electromagnetic field DC motors, the stator core's magnetic pole forms the magnetic circuit and gets activated by direct current. This eliminates the necessity for lamination, opting instead for the use of soft steel.

On the other hand, a laminated core is utilized for the rotor core to set up the armature circuit, adjusting to the changing flux during rotation. Moreover, compact DC motors commonly integrate permanent magnets for the magnetic pole. Stators of synchronous motors and both the stator and rotor of induction motors are powered by alternating current (AC), requiring laminated cores for effective operation of all parts.

(3) Insulator (Insulating material)

Insulators are crucial elements within electrical systems, as they play a key role in directing electric current along its designated route and thwarting any undesired seepage. Any substances with insulating characteristics are commonly referred to as insulating materials.

A diverse range of substances is utilized as insulators in various applications. These materials, such as rubber, enamel, high-molecular compounds, resins, paper, mica, and glass fiber, are selected specifically for their capability to impede the passage of electricity, ensuring effective electrical isolation between different conducting components.

(4) Permanent magnet

Within the intricate design of an electric motor, permanent magnets play a crucial role given their unique ability to produce magnetic fields crucial for the motor's function. These magnets, classified as a specific type of iron-based alloys or oxides, play a vital role in creating and sustaining magnetic fields within the motor's essential parts. Their permanent magnetization sets them apart from other types, guaranteeing enduring and dependable performance throughout the motor's operational lifespan.