Basics of Synchronous Motors

Synchronous motors work well at a constant speed, following a precise rhythm with the electrical current to ensure smooth and efficient performance. 

Have you ever wondered how your appliances maintain a constant speed and operate smoothly? It's all thanks to the synchronous motors that keep things running smoothly. In this blog, we will explore everything about synchronous motors, from who they are, how they work, where they are used, and how they're surviving in today's tech-driven world. 

What is a Synchronous Motor?

A synchronous motor is a type of electric motor, where the rotational speed of the motor is synchronized with the frequency of electrical current. This synchronization is achieved as the rotor rotates at the same speed as the magnetic field generated by the stator. 

There are two main categories of synchronous motors: non-excited (or reluctance) synchronous motors and excited synchronous motors. In non-excited synchronous motors, the rotor lacks winding and relies on the magnetic field produced by the stator to achieve synchronized rotation. These motors are used in applications where constant speed is required such as clocks, and turntables. 

While in an excited synchronous motor, the rotors consist of winding. When DC current is supplied to these windings, it creates a magnetic field and allows precise control over the speed and torque of the motor. These motors are used in various applications such as large fans, pumps, compressors, and generators. 

Therefore, Synchronous motors are known for their efficiency, reliability, and ability to maintain a constant speed even under varying loads. 

Construction of Synchronous Motor

A synchronous motor consists of various parts such as a stator, rotor, excitation system, bearings, and many more. 

All these parts work together to rotate the rotor at a synchronized speed with the help of AC supply. The key components of the synchronous motor are : 

• Stator

It is the stationary part of the motor. It consists of a stack of thin, insulated laminated sheets and other magnetic materials. These laminations are stacked to form the core of the stator. The core of the stator consists of coils of wire wound around the slots and form the winding of the motor. When AC is supplied through this winding, it produces a magnetic field to rotate the rotor.

• Rotor

It is the rotating part of the motor. It consists of steel lamination, copper conductors, and permanent magnets. When AC is supplied through the winding of the stator, it generates the magnetic field, then the rotor interacts with the magnetic field and rotates the motor at a synchronized speed.

•  Exciter

It is a crucial component of a synchronous motor. It is responsible for maintaining the synchronous speed of the motor. Adjusting the phase of direct current (DC) supplies to the rotor, ensures that the rotors rotate at the same speed as stator winding. It helps the motor to rotate at its constant speed and to maintain its stability. 

• Bearing

It plays a critical role in a synchronous motor. It provides support to the rotor shaft to maintain its position and allows it to rotate freely. There are 3 types of bearings such as sleeve bearings, roller bearings, and ball bearings. 

Sleeve bearings made up of bronze allow smooth rotation of the rotor by providing low friction. Roller bearings use cylindrical and tapper rollers to reduce friction and handle high radial loads. Ball bearing uses balls to minimize friction.

They are efficient in handling the axial loads. Bearings need timely inspection to avoid wear and tear, maintenance, and potential failures to improve the efficiency of the motor. 

Other Components 

• Shaft

It connects the rotor with the external load of the motor. It helps to transmit the rotational force produced by the motor to the application. 

• Housing or Frame

It protects the internal components of synchronous motors. It provides structural support and consists of a bearing, stator, rotor, and exciter.

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Working Principle of Synchronous Motor

Applications of Synchronous Motor

• Power Generation Plant

Synchronous motors are used in power generation plants as synchronous generators. They convert the mechanical energy into electrical energy. They are connected to turbines and driven by steam, wind, and water. As a synchronous generator, it rotates at a synchronized speed and produces electricity. 

Synchronous motors are also used for power factor correction in the plants. They regulate the power factor by adjusting the exciter and allowing it to absorb or supply reactive power, regulating the voltage supply and overall efficiency of the system. 

• Industrial Machinery

Synchronous motors are used in industrial applications to perform various tasks that demand constant speed and reliability. These motors are used in machine tools such as lathes, milling machines, and grinders where constant speed is required for precise cutting and finishing of the materials. 

Synchronous motors play a pivotal role in the conveyor systems of factories and warehouses. These motors provide constant speed and precise control which allow the smooth movement of goods from the assembly line to the packaging area. 

• Printing Presses

Synchronous motors are important components in printing presses by facilitating constant speed and accurate control in the printing operation. These motors help in maintaining the accurate alignment of printing plates. This alignment helps in aligning each color and element properly. 

These motors offer constant speed and rotation which is crucial for aligning color, text, and design accurately on paper. Printing presses print different types of formats and designs, The motor's constant speed and precise control help to control the printing speed and improve the flexibility of the printing process. 

Mechtex is a permanent magnet synchronous motor manufacturer in India since 1967. We provide 12V Synchronous Motor, 24V Synchronous Motor, 110V Synchronous Motor, and 230V Synchronous Motor, and 3-phase Synchronous Motor, with power ranging from 3W to 30W and torque ranging from 0.2 Ncm to 10.2 Ncm. 

• Synchronization Applications 

Synchronous motors are used in various synchronization applications such as clock and timing devices, industrial automation, Audio and broadcast systems, and telecommunication devices.  

These motors are the driving force in clock and timing devices. The devices function with the help of the synchronized speed of the motor. This synchronization helps in accurate timekeeping and continuous functioning of devices, It is commonly found in public clocks and industrial timekeeping systems. 

Synchronous motors are used in multiple industrial automation applications such as CNC machines, Printing presses, packaging machines, and many more. The motor’s precise speed and accurate control help CNC machines and automated manufacturing processes in repeatable movement. The motor's constant speed and accuracy help packaging machines and printing presses perform tasks with accuracy. 

Why are Synchronous Motors Important in today's world?

In recent times, the world has experienced a shift toward new motor technology due to various factors such as the advancement in technology, changing consumer preferences, the need for efficient and sustainable solutions, and an increase in environmental standards and regulations. 

This shift led to the adoption of brushless DC motors and permanent magnet motors. These motors are key in driving progress and fulfilling the demand for efficient and sustainable solutions. Their ability to control speed and torque caters to the requirements of modern industrial technology.

Despite advancements in technology and new types of motors,  synchronous motors are still crucial components for various industrial applications. 

One of the key reasons to continue the use of synchronous motors is their constant speed and high efficiency. Their constant speed makes them ideal for applications that require stable and continuous rotation for their operations. 

Another key reason to use synchronous motors in today's industrial applications is their ability to operate in both motor and generator mode. In the motor mode, it converts the electrical energy into mechanical energy while in generator mode, it converts the mechanical energy into electrical energy. This ability makes them a reliable solution for applications such as wind turbines, power generation plants, and hybrid vehicles. 

In addition to all the technical advantages,  synchronous motors also offer environmental advantages. These motors offer a low carbon footprint as compared to other motors as they are not made up of rare earth magnet materials. These motors result in less power consumption as they operate at a constant speed with a low power supply.