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Lower Energy Cost Three Phase Neodymium Magnet Motor Factory
What Is The Permanent Magnet Synchronous Motor?
Permanent Magnet Synchronous Motor (PMSM) is brushless and has very high reliability and efficiency. Due to its permanent magnet rotor, it also has a high torque with a small frame size and no rotor current. Instead of using winding for the rotor, permanent magnets are mounted to create a rotating magnetic field. As there is no supply of DC source, these types of motors are very simple and less cost. The permanent magnet synchronous motors are AC synchronous motor whose field excitation is provided by permanent magnets and that has a sinusoidal back EMF waveform. The permanent magnets enable the PMSM to generate torque at zero speed. This motor delivers high-efficiency operations and requires a digitally controlled inverter.
Analysis of the principle of the technical advantages of permanent magnet motor
The principle of a permanent magnet synchronous motor is as follows: In the motor's stator winding into the three-phase current, after the pass-in current, it will form a rotating magnetic field for the motor's stator winding. Because the rotor is installed with the permanent magnet, the permanent magnet's magnetic pole is fixed, according to the principle of magnetic poles of the same phase attracting different repulsion, the rotating magnetic field generated in the stator will drive the rotor to rotate, The rotation speed of the rotor is equal to the speed of the rotating pole produced in the stator.
Due to the use of permanent magnets to provide magnetic fields, the rotor process is mature, reliable, and flexible in size, and the design capacity can be as small as tens of watts, up to megawatts. At the same time, by increasing or decreasing the number of pairs of rotor permanent magnets, it is easier to change the number of poles of the motor, which makes the speed range of permanent magnet synchronous motors wider. With multi-pole permanent magnet rotors, the rated speed can be as low as a single digit, which is difficult to achieve by ordinary asynchronous motors.
Especially in the low-speed high-power application environment, the permanent magnet synchronous motor can be directly driven by a multi-pole design at low speed, compared with an ordinary motor plus reducer, the advantages of a permanent magnet synchronous motor can be highlighted.
Differences Between The Permanent Magnet Motor And Asynchronous Motor:
01. Rotor Structure
Asynchronous motor: The rotor consists of an iron core and a winding, mainly squirrel-cage and wire-wound rotors. A squirrel-cage rotor is cast with aluminum bars. The magnetic field of the aluminum bar cutting the stator drives the rotor.
PMSM Motor: The permanent magnets are embedded in the rotor magnetic poles, and are driven to rotate by the rotating magnetic field generated in the stator according to the principle of magnetic poles of the same phase attracting different repulsions.
02. Efficiency
Asynchronous motors: Need to absorb current from the grid excitation, resulting in a certain amount of energy loss, motor reactive current, and low power factor.
PMSM Motor: The magnetic field is provided by permanent magnets, the rotor does not need exciting current, and the motor efficiency is improved.
03. Volume And Weight
The use of high-performance permanent magnet materials makes the air gap magnetic field of permanent magnet synchronous motors larger than that of asynchronous motors. The size and weight are reduced compared to asynchronous motors. It will be one or two frame sizes lower than asynchronous motors.
04. Motor Starting Current
Asynchronous motor: It is directly started by power frequency electricity, and the starting current is large, which can reach 5 to 7 times the rated current, which has a great impact on the power grid in an instant. The large starting current causes the leakage resistance voltage drop of the stator winding to increase, and the starting torque is small so heavy-duty starting cannot be achieved. Even if the inverter is used, it can only start within the rated output current range.
PMSM Motor: It is driven by a dedicated controller, which lacks the rated output requirements of the reducer. The actual starting current is small, the current is gradually increased according to the load, and the starting torque is large.
05. Power Factor
Asynchronous motors have a low power factor, they must absorb a large amount of reactive current from the power grid, the large starting current of asynchronous motors will cause a short-term impact on the power grid, and long-term use will cause certain damage to the power grid equipment and transformers. It is necessary to add power compensation units and perform reactive power compensation to ensure the quality of the power grid and increase the cost of equipment use.
There is no induced current in the rotor of the permanent magnet synchronous motor, and the power factor of the motor is high, which improves the quality factor of the power grid and eliminates the need to install a compensator.
06. Maintenance
Asynchronous motor + reducer structure will generate vibration, heat, high failure rate, large lubricant consumption, and high manual maintenance cost; it will cause certain downtime losses.
The three-phase Permanent magnet synchronous motor drives the equipment directly. Because the reducer is eliminated, the motor output speed is low, mechanical noise is low, mechanical vibration is small, and the failure rate is low. The entire drive system is almost maintenance-free.
The three-phase Permanent magnet synchronous motor drives the equipment directly. Because the reducer is eliminated, the motor output speed is low, mechanical noise is low, mechanical vibration is small, and the failure rate is low. The entire drive system is almost maintenance-free.
The permanent magnet synchronous motor has the following characteristics:
In the general industrial sector, the replacement of low-voltage(380/660/1140V) high-efficiency asynchronous motors, the system saves 5% to 30% energy, and the high-voltage(6kV/10kV) high-efficiency asynchronous motors, the system saves 2% to10%.
Why choose permanent magnet ac motors?
Permanent magnet AC (PMAC) motors offer several advantages over other types of motors, including:
High Efficiency: PMAC motors are highly efficient due to the absence of rotor copper losses and reduced winding losses. They can achieve efficiencies of up to 97%, resulting in significant energy savings.
High Power Density: PMAC motors have a higher power density compared to other motor types, which means they can produce more power per unit of size and weight. This makes them ideal for applications where space is limited.
High Torque Density: PMAC motors have a high torque density, which means they can produce more torque per unit of size and weight. This makes them ideal for applications where high torque is required.
Reduced Maintenance: Since PMAC motors have no brushes, they require less maintenance and have a longer lifespan than other motor types.
Improved Control: PMAC motors have better speed and torque control compared to other motor types, making them ideal for applications where precise control is required.
Environmentally Friendly: PMAC motors are more environmentally friendly than other motor types since they use rare earth metals, which are easier to recycle and produce less waste compared to other motor types.
Overall, the advantages of PMAC motors make them an excellent choice for a wide range of applications, including electric vehicles, industrial machinery, and renewable energy systems.
Application:
Permanent magnet synchronous motors can be combined with frequency converters to form the best open-loop step-less speed control system, which has been widely used for speed control transmission equipment in petrochemical, chemical fiber, textile, machinery, electronics, glass, rubber, packaging, printing, paper making, printing and dyeing, metallurgy and other industries.
A permanent magnet motor (also called PM) can be separated into two main categories: Interior Permanent Magnet (IPM) and Surface Permanent Magnet (SPM). Both types generate magnetic flux by the permanent magnets affixed to or inside of the rotor.
SPM
SURFACE PERMANENT MAGNET
A type of motor in which permanent magnets are attached to the rotor circumference.
SPM motors have magnets affixed to the exterior of the rotor surface, their mechanical strength is so weaker than the IPM one. The weakened mechanical strength limits the motor’s maximum safe mechanical speed. In addition, these motors exhibit very limited magnetic saliency (Ld ≈ Lq). Inductance values measured at the rotor terminals are consistent regardless of the rotor position. Because of the near unity saliency ratio, SPM motor designs rely significantly, if not completely, on the magnetic torque component to produce torque.
IPM
INTERIOR PERMANENT MAGNET
A type of motor that has a rotor embedded with permanent magnets is called IPM.
IPM motors have a permanent magnet embedded into the rotor itself. Unlike their SPM counterparts, the location of the permanent magnets makes IPM motors very mechanically sound, and suitable for operating at very high speeds. These motors also are defined by their relatively high magnetic saliency ratio (Lq > Ld). Due to their magnetic saliency, an IPM motor has the ability to generate torque by taking advantage of both the magnetic and reluctance torque components of the motor.
Why you should choose an IPM motor instead of an SPM?
1. High torque is achieved by using reluctance torque in addition to magnetic torque.
2. IPM motors consume up to 30% less power compared to conventional electric motors.
3. Mechanical safety is improved as, unlike in an SPM, the magnet will not detach due to centrifugal force.
4. It can respond to high-speed motor rotation by controlling the two types of torque using vector control.
Brushless permanent magnet (PM) motors operate with an AC power supply so are often referred to as PMAC motors. The use of permanent magnets eliminates the need for conductors (rotor bars) so rotor losses are eliminated. This design makes it possible to combine high efficiency, low speed, and high torque in a single package. For small motor sizes, the efficiency of the PM motor maybe 10% to 15% greater than older, standard-efficiency motors at the same load point. These efficiency gains hold over the entire range of typical motor loads.
Will the permanent magnet motor demagnetize?
It is possible for a permanent magnet motor to demagnetize, but it is generally unlikely under normal operating conditions. Permanent magnets are made of materials such as neodymium, samarium cobalt, or ferrite, which are highly resistant to demagnetization. These materials are chosen specifically because they have high magnetic coercivity, which means that they are able to resist demagnetization forces.
However, there are some situations that could lead to the demagnetization of the permanent magnets in a motor. For example, if the motor is exposed to extremely high temperatures, above the maximum operating temperature specified by the manufacturer, the permanent magnets could lose their magnetic strength over time. Additionally, exposure to a strong external magnetic field or mechanical shock could also potentially demagnetize the magnets.
To prevent demagnetization of the permanent magnets in a motor, it is important to operate the motor within its specified temperature range and to avoid exposing it to strong magnetic fields or mechanical shocks. Additionally, some manufacturers may use methods such as heat treatment or magnetizing in a particular direction to enhance the resistance of the magnets to demagnetization.
Due to the need for a drive or controller, variable-speed PMAC motors cost much more than constant-speed Premium Efficiency induction motors. PM motors have the variable-speed capability, however, so are equivalent replacements for an electronic pulse-width modulated variable frequency drive (VFD) controlling a new Premium Efficiency inverter-duty motor. When replacing constant-speed motors in variable flow applications, energy savings due to the variable-speed capability of the PMAC motor will greatly exceed the savings due to the increased efficiency of the motor itself. Permanent magnet motors provide improved efficiency over their entire operating range and meet or exceed the International Electrotechnical Commission (IEC) IE4 efficiency standards.
ENNENG is dedicated to providing customers with stable and energy-efficient permanent magnet motors and solutions, not only saving large amounts of energy and cost for our customers but also contributing to the energy conservation and emission reduction of the social.
