Due to the incomparable superiority of variable frequency motors in speed regulation and control, the degree of mechanical automation and production efficiency have been greatly improved; EPS power supply has its particularity as the future development trend of frequency converter technology, but due to the high speed requirements of the variable frequency motor system Or low-speed operation, dynamic response of speed and other requirements, the stringent requirements for the motor as the main power will bring innovations in electromagnetic, structure, insulation and other aspects to the variable frequency motor.

It can be said that due to the superiority of variable frequency motors over ordinary motors in terms of variable frequency control, it is not difficult to see variable frequency motors wherever frequency converters are used.

The technical parameters of the variable frequency speed motor include:

1. Rated power: the maximum sustainable output power of the motor.

2. Rated speed: The theoretical maximum speed of the motor operating at rated power.

3. Rated voltage: The rated operating voltage of the motor.

4. Rated current : The current value of the motor under rated condition.

5. Rated frequency: The frequency at which the motor is designed to operate.

6. Cooling method: There are two common cooling methods for motors: air cooling and water cooling.

7. Insulation level: The insulation performance level of the motor, usually Class F, Class H, Class B, etc.

8. Speed adjustment range: the speed adjustment range that the motor can achieve, usually 20%-100%.

9. Balance level: The balance performance level of the motor, usually G0.4 or G2.5.

10. Noise: The noise level of the motor, usually expressed in decibels (dB).

11. Dimensions and weight: Dimensions and weight of the motor.

12. Protection level: The protection level of the motor, usually expressed as IPXX level.

Frequency conversion speed motor parameter selection method

1. Frequency conversion speed motor power

The power characteristic curve determines the output power of the motor at various speeds. In the design, at any speed, the output power of the motor is greater than or equal to the required power. Although the motor can work within the speed range, it should be noted that , when the motor works in the low speed section of the constant torque area, the power factor of the motor is very low and the efficiency is very low. When a motor approaches its minimum speed, its efficiency is only a few percent. The motor heats up at a high rate and consumes a lot of power. Should not be used for heavy use, only for short periods of time. When this requirement cannot be met, deceleration measures should be taken to make the motor output to the actuator at a higher speed and at a low speed. When the motor is connected in series with the variable speed, the rotational speed is distributed into a high-speed transmission area and a low-speed transmission area. The transmission ratio is selected for the rotational speed distribution to minimize the rated power of the motor and reasonably consider the connection of the power curve.

2. Frequency conversion speed motor speed range

Among the basic parameters of the variable frequency speed motor , the rated speed NO, frequency range FMAX and fmin are given. There are several motor frequency ranges to choose from. Different products need to be found . When the motor speed range cannot meet the actual needs In this case, a series transmission group can be used to expand the speed regulation range.

3. Accuracy requirements for variable frequency speed motors

The accuracy of the variable frequency speed motor has an impact on the output accuracy in direct proportion to the total transmission ratio. When the accuracy of the motor cannot meet the requirements, the reduction drive can improve . If the requirements cannot be met, a servo motor must be used .

4.Other requirements

Mainly the starting characteristics and protection performance of the variable frequency speed motor. Starting characteristics: When the system starts with load, since the friction coefficient of the moving parts is the largest static friction coefficient, the starting load is the largest and the torque required for normal operation is greatly reduced. Therefore, in the case of excessive waste of high-power motors , the required torque is maximum during the static process and accelerates to a certain speed. Therefore, it can be selected or customized according to requirements (in the starting area of Figure 1, most motors are started with constant torque, but there are also some motors with larger starting torque, and the starting torque is several times the constant torque ).

5. Response speed requirements

The response speed of the variable frequency speed motor mainly affects the acceleration performance of the system. The response parameters of the motor are determined by the output torque of the motor and its own moment of inertia. The system response should be determined by the motor torque and the equivalent moment of inertia converted by the system to the motor shaft. calculate.