Product Details
High Torque And High-Efficiency Direct Drive 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.
Detailed pictures
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
Structure of the IPM (interior permanent magnet) motor
A conventional SPM (surface permanent magnet) motor has a structure
in which a permanent magnet is attached to the rotor surface. It
only uses magnetic torque from a magnet. On the other hand, the IPM
motor uses reluctance through magnetic resistance in addition to
magnetic torque by embedding a permanent magnet in the rotor
itself.
SPM vs IPM Motor Rotor Structure
IPM (Interior Permanent Magnet) Motor Features
High torque and high efficiency
High torque and high output are achieved by using reluctance torque
in addition to magnetic torque.
Energy-saving operation
It consumes up to 30% less power compared to conventional SPM
motors.
High-speed rotation
It can respond to high-speed motor rotation by controlling the two
types of torque using vector control.
Safety
Since the permanent magnet is embedded, mechanical safety is
improved as, unlike in an SPM, the magnet will not detach due to
centrifugal force.
Vector Control Features
While a conventional system (120-degree conduction system) has the
current impressed in the motor as a square wave, a vector control
impresses voltage which turns into a sine wave towards the rotor's
position (angle of the magnet), so it becomes possible to control
the motor current.
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.
Features Of Rare-Earth Permanent Magnet Motors
The rotor pole of the rare earth permanent magnet motor is composed
of rare earth permanent magnet steel, so there is no slip, no
excitation current, and the rotor has no fundamental wave iron and
copper wear.
The rotor is excited by permanent magnets, and no reactive
excitation current is needed. Therefore, the power factor is
improved, the reactive power is reduced, the stator current is
greatly reduced, and the stator copper and iron losses are greatly
reduced.
At the same time, because the polar arc coefficient of the rare
earth permanent magnet motor is larger than that of the
asynchronous motor when the voltage and the stator structure are
constant, the average magnetic induction intensity of the motor is
smaller than that of the asynchronous motor and the iron loss is
small.
Therefore, it can be said that the rare earth permanent magnet
synchronous motor is energy-saving by reducing its own losses, and
is not affected by changes in operating conditions, environment,
and other factors.
Advantages Of Rare-earth Permanent Magnet Motors
- High efficiency: The efficiency curve of the asynchronous motor
generally falls faster under 60% of the rated load, and the
efficiency is very low at light load. The efficiency curve of the
rare earth permanent magnet motor is high and flat, and it is in
the high-efficiency area at 20%~120% of the rated load.
- High power factor: The measured value of the power factor of the
rare earth permanent magnet synchronous motor is close to the limit
value of 1.0. The power factor curve is as high and flat as the
efficiency curve. The power factor is high. Low-voltage reactive
power compensation is not required and the power distribution
system capacity is fully utilized.
- Stator current is small: The rotor has no excitation current, the
reactive power is reduced, and the stator current is significantly
reduced. Compared with the asynchronous motor of the same capacity,
the stator current value can be reduced by 30% to 50%. At the same
time, because the stator current is greatly reduced, the motor
temperature rise is reduced, and the bearing grease and bearing
life are extended.
- High out-of-step torque and pull-in torque: Rare earth permanent
magnet synchronous motors have higher out-of-step torque and
pull-in torque, which makes the motor have higher load capacity and
can be smoothly pulled into synchronization.
Disadvantages Of Rare-earth Permanent Magnet Motors
- High cost: Compared with the asynchronous motor of the same
specification, the air gap between the stator and the rotor is
smaller, and the processing accuracy of each component is high; the
rotor structure is more complicated and the price of rare earth
magnetic steel material is high; therefore, the motor manufacturing
cost is high, which is common for asynchronous motors About 2
times.
- Large impact at full power start: When starting at full pressure,
the synchronous speed can be drawn in a very short time. The
mechanical shock is large. The starting current is more than 10
times the rated current. The impact on the power supply system is
large, requiring a large capacity of the power supply system.
- Rare-earth magnet steel is easy to demagnetize: When the permanent
magnet material is subjected to vibration, high temperature, and
overload current, its magnetic permeability may decrease, or the
demagnetization phenomenon occurs, which reduces the performance of
the permanent magnet motor.
Company Profile
The value of Enneng is Technology is how we do things. People are
why we do things.
As a leading manufacturer of permanent magnet AC motors and
generators, Enneng is committed to providing the best solutions for
our customers while also prioritizing energy savings and low carbon
emissions. We believe that it is our responsibility to contribute
to a sustainable future by promoting energy-efficient solutions and
reducing our carbon footprint.
Enneng Motor has been committed to the research and development of
various permanent magnet AC motors that can directly drive
equipment, usually low-speed, high-torque motors, optimized for
mechanical equipment with reducer + motor drive in the transmission
system. These motors usually have a durable design, high
efficiency, and low noise level, and can provide customers with
customized services from equipment transmission design to provide
special sizes and rated power options to meet the needs of
different applications, so as to achieve energy-saving performance.
Honors
Permanent magnet generators are suitable for small and low-head
hydro sites and small and low-speed wind power generation. Our
products are highly efficient and reliable, making it possible for
more and more small-size hydro and wind power generation projects
to become feasible.
Certifications
Our mission is to help our customers succeed by providing effective
solutions. We believe that by providing high-quality permanent
magnet generators, we can help our customers to successfully build
sustainable and environmentally friendly energy systems. We invite
you to join us in our mission to build a more sustainable world
together.