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Long Lifespan Industrial Use Energy Efficient Three Phase Permanent Magnet Motor
What Is The Permanent Magnet Synchronous Motor?
The PERMANENT MAGNET SYNCHRONOUS MOTOR is mainly composed of the
stator, rotor, chassis, front-rear cover, bearings, etc. The
structure of the stator is basically the same as that of ordinary
asynchronous motors, and the main difference between the permanent
magnet synchronous motor and other kinds of motors is its rotor.
The permanent magnet material with pre-magnetized (magnetic
charged) magnetic on the surface or inside the permanent magnet of
the motor, provides the necessary air gap magnetic field for the
motor. This rotor structure can effectively reduce the motor
volume, reduce loss and improve efficiency.
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.
Permanent magnet AC (PMAC) motors have a wide range of applications
including:
Industrial Machinery: PMAC motors are used in a variety of
industrial machinery applications, such as pumps, compressors,
fans, and machine tools. They offer high efficiency, high power
density, and precise control, making them ideal for these
applications.
Robotics: PMAC motors are used in robotics and automation
applications, where they offer high torque density, precise
control, and high efficiency. They are often used in robotic arms,
grippers, and other motion control systems.
HVAC Systems: PMAC motors are used in heating, ventilation, and air
conditioning (HVAC) systems, where they offer high efficiency,
precise control, and low noise levels. They are often used in fans
and pumps in these systems.
Renewable Energy Systems: PMAC motors are used in renewable energy
systems, such as wind turbines and solar trackers, where they offer
high efficiency, high power density, and precise control. They are
often used in the generators and tracking systems in these systems.
Medical Equipment: PMAC motors are used in medical equipment, such
as MRI machines, where they offer high torque density, precise
control, and low noise levels. They are often used in the motors
that drive the moving parts in these machines.
Working Principle
The permanent magnet synchronous motor working principle is similar
to the synchronous motor. It depends on the rotating magnetic field
that generates electromotive force at synchronous speed. When the
stator winding is energized by giving the 3-phase supply, a
rotating magnetic field is created in between the air gaps.
This produces the torque when the rotor field poles hold the
rotating magnetic field at synchronous speed and the rotor rotates
continuously. As these motors are not self-starting motors, it is
necessary to provide a variable frequency power supply.
EMF and Torque Equation
In a synchronous machine, the average EMF induced per phase is
called dynamic induces EMF in a synchronous motor, the flux cut by
each conductor per revolution is Pϕ Weber
Then the time taken to complete one revolution is 60/N sec
The average EMF induced per conductor can be calculated by using
( PϕN / 60 ) x Zph = ( PϕN / 60 ) x 2Tph
Where Tph = Zph / 2
Therefore, the average EMF per phase is,
= 4 x ϕ x Tph x PN/120 = 4ϕfTph
Where Tph = no. Of turns connected in series per phase
ϕ = flux/pole in Weber
P= no. Of poles
F= frequency in Hz
Zph= no. Of conductors connected in series per phase. = Zph/3
The EMF equation depends on the coils and the conductors on the
stator. For this motor, the distribution factor Kd and pitch factor
Kp are also considered.
Hence, E = 4 x ϕ x f x Tph xKd x Kp
The torque equation of a permanent magnet synchronous motor is
given as,
T = (3 x Eph x Iph x sinβ) / ωm
Surface-mounted PMSM
In this construction, the magnet is mounted on the surface of the
rotor. It is suited for high-speed applications, as it is not
robust. It provides a uniform air gap because the permeability of
the permanent magnet and the air gap is the same. No reluctance
torque, high dynamic performance, and suitable for high-speed
devices like robotics and tool drives.
Buried PMSM or Interior PMSM
In this type of construction, the permanent magnet is embedded into
the rotor as shown in the figure below. It is suitable for
high-speed applications and gets robust. Reluctance torque is due
to the saliency of the motor.
Working of Permanent Magnet Synchronous Motor
The working of the permanent magnet synchronous motor is very
simple, fast, and effective when compared to conventional motors.
The working of PMSM depends on the rotating magnetic field of the
stator and the constant magnetic field of the rotor. The permanent
magnets are used as the rotor to create constant magnetic flux and
operate and lock at synchronous speed. These types of motors are
similar to brushless DC motors.
The phasor groups are formed by joining the windings of the stator
with one another. These phasor groups are joined together to form
different connections like a star, Delta, and double and single
phases. To reduce harmonic voltages, the windings should be wound
shortly with each other.
When the 3-phase AC supply is given to the stator, it creates a
rotating magnetic field and the constant magnetic field is induced
due to the permanent magnet of the rotor. This rotor operates in
synchronism with the synchronous speed. The whole working of the
PMSM depends on the air gap between the stator and rotor with no
load.
If the air gap is large, then the windage losses of the motor will
be reduced. The field poles created by the permanent magnet are
salient. The permanent magnet synchronous motors are not
self-starting motors. So, it is necessary to control the variable
frequency of the stator electronically.
Advantages
The advantages of permanent magnet synchronous motor include,
provides higher efficiency at high speeds
available in small sizes in different packages
maintenance and installation are very easy than with an induction
motor
capable of maintaining full torque at low speeds
high efficiency and reliability
gives smooth torque and dynamic performance
Disadvantages
The disadvantages of permanent magnet synchronous motors are:
These types of motors are very expensive when compared to induction
motors
Somehow difficult to start up because they are not self-starting
motors.