Custom AC Direct Drive Permanent Magnet Motor Highly Integrated Synchronous Electric Motors

Permanent magnet synchronous motors with internal magnets: Maximum energy efficiency
The permanent magnet synchronous motor with internal magnets (IPMSM) is the ideal motor for traction applications where the maximum torque does not occur at maximum speed. This type of motor is used in applications that require high dynamics and overload capacity. And it is also the perfect choice if you want to operate fans or pumps in the IE4 and IE5 range. The high purchase costs are usually recouped through energy savings over the run time, provided that you operate it with the right variable frequency drive.

Our motor-mounted variable frequency drives use an integrated control strategy based on MTPA (Maximum Torque per Ampere). This allows you to operate your permanent magnet synchronous motors with maximum energy efficiency. The overload of 200 %, the excellent starting torque, and the extended speed control range also allow you to fully exploit the motor rating. For fast recovery of costs and the most efficient control processes.

Permanent magnet synchronous motors with external magnets for classic servo applications
Permanent magnet synchronous motors with external magnets (SPMSM) are ideal motors when you need high overloads and rapid acceleration, for example in classic servo applications. The elongated design also results in low mass inertia and can be optimally installed. However, one disadvantage of the system consisting of SPMSM and variable frequency drive is the costs associated with it, as expensive plug technology and high-quality encoders are often used.

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.

How to improve the efficiency of the motor?

To improve the efficiency of the motor, the essence is to reduce the loss of the motor. The loss of the motor is divided into mechanical loss and electromagnetic loss. For example, for an AC asynchronous motor, the current passes through the stator and rotor windings, which will produce copper loss and conductor loss, while the magnetic field in the iron. It will cause eddy currents to bring about hysteresis loss, high harmonics of the air magnetic field will generate stray losses on the load, and there will be wear losses during the rotation of bearings and fans.

To reduce the loss of the rotor, you can reduce the resistance of the rotor winding, use a relatively thick wire with low resistivity, or increase the cross-sectional area of the rotor slot. Of course, the material is very important. Conditional production of copper rotors will reduce losses by about 15%. The current asynchronous motors are basically aluminum rotors, so the efficiency is not so high.

Similarly, there is copper loss on the stator, which can increase the slot face of the stator, increase the full slot ratio of the stator slot, and shorten the end length of the stator winding. If a permanent magnet is used to replace the stator winding, there is no need to pass current. Of course, the efficiency can be obviously improved, which is the fundamental reason why the synchronous motor is more efficient than the asynchronous motor.

For the iron loss of the motor, high-quality silicon steel sheets can be used to reduce the loss of the hysteresis or the length of the iron core can be lengthened, which can reduce the magnetic flux density, and can also increase the insulating coating. In addition, the heat treatment process is also critical.

The ventilation performance of the motor is more important. When the temperature is high, the loss will of course be large. The corresponding cooling structure or additional cooling method can be used to reduce friction loss.

High-order harmonics will produce stray losses in the winding and iron core, which can improve the stator winding and reduce the generation of high-order harmonics. Insulation treatment can also be performed on the surface of the rotor slot, and magnetic slot mud can be used to reduce the magnetic slot effect.

A few small problems that are easily overlooked about the motor

1. Why can't general motors be used in plateau areas?

Altitude has adverse effects on motor temperature rise, motor corona (high voltage motor) and commutation of DC motor. The following three aspects should be noted:

(1) The higher the altitude, the higher the temperature rise of the motor, the lower the output power. However, when the temperature decreases with the increase of altitude enough to compensate for the influence of altitude on the temperature rise, the rated output power of the motor can remain unchanged;

(2) Anti-corona measures should be taken when the high-voltage motor is used in the plateau;

(3) The altitude is not good for the commutation of the DC motor, so pay attention to the selection of carbon brush materials.

2. Why is the motor not suitable for light load operation?

When the motor runs at light load, it will cause:

(1) The power factor of the motor is low;

(2) The motor efficiency is low.

(3) It will cause equipment waste and uneconomical operation.

3. Why can't the motor start in cold environment?

Excessive use of the motor in a low temperature environment will cause:

(1) Motor insulation cracks;

(2) Bearing grease freezes;

(3) The solder powder of the wire joint is powdered.

Therefore, the motor should be heated and stored in a cold environment, and the windings and bearings should be checked before running.

4. Why can't a 60Hz motor use a 50Hz power supply?

When the motor is designed, the silicon steel sheet generally works in the saturation region of the magnetization curve. When the power supply voltage is constant, reducing the frequency will increase the magnetic flux and the excitation current, resulting in an increase in the motor current and copper consumption, which will eventually lead to an increase in the temperature rise of the motor. In severe cases, the motor may be burned due to overheating of the coil.

5.Motor soft start

Soft start has limited energy-saving effect, but it can reduce the impact of start-up on the power grid, and can also achieve smooth start to protect the motor unit. According to the theory of energy conservation, due to the addition of a relatively complex control circuit, soft start not only does not save energy, and also increases energy consumption. But it can reduce the starting current of the circuit and play a protective role.