Video: Cooling Fans for Inverter Motors: Necessity, Intelligent Control and Selection Precautions
Figure 1: Cooling fan for inverter motor.
Since the inverter motor generates a large amount of heat when running, and poor heat dissipation will cause the motor temperature to be too high, thereby reducing the life and efficiency of the motor, and even causing damage to the motor, the heat needs to be dissipated. The cooling fan absorbs the surrounding air and sends it into the motor, thereby taking away the heat generated by the motor and maintaining the normal operating temperature of the motor.
The fan is a ventilation and heat dissipation device matched to the inverter motor. Based on the structural characteristics of the motor, there are two fan types: axial flow fan and centrifugal fan.
The axial flow fan is installed at the non-shaft extension end of the motor and is functionally equivalent to the external fan and fan cover of the industrial frequency motor.
The centrifugal fan is installed at the appropriate position of the motor according to the motor body structure and the specific functions of some additional devices.
1. Necessity of Using Independent Fans for Inverter Motors
For situations where the motor frequency variation range is small and the motor temperature rise margin is large, the fan structure of the industrial frequency motor can also be used. For situations where the motor operating frequency range is wide, in principle, an independent fan should be installed.
The reason why it is called an independent fan is, on the one hand, its relative independence from the mechanical part of the motor, and on the other hand, the relative independence of the fan power supply and the motor power supply, that is, the the fan and the motor cannot share a set of power supply.
The inverter motor is powered by a variable frequency power supply or a frequency converter, and the motor speed is variable. The structure of the motor with a built-in fan cannot meet the heat dissipation requirements of the motor at all operating speeds. Especially when running at low speeds, it will result in an imbalance between the heat generated by the motor and the heat taken away by cooling medium air whose flow is severely insufficient.
Figure 2: Motor mechanical structure.
An independent fan can meet this demand:
(1) The speed of the independently operating fan is not affected by speed changes of the motor during operation. It is always set to take precedence over the start of the motor and lag behind the stop of the motor, which can better meet the ventilation and heat dissipation requirements of the motor.
(2) The power, speed and other parameters of the fan can be appropriately adjusted based on the design temperature rise margin of the motor. The fan motor and the motor body can have different numbers of poles, and can also have different voltage levels when conditions permit.
(3) For structures with many additional motor components, the design of the fan can be adjusted to minimize the overall size of the motor while meeting ventilation and heat dissipation requirements.
(4) As for the motor body, since there is no built-in fan, the mechanical loss of the motor will be reduced, which has a certain effect on improving motor efficiency.
(5) From the analysis of the vibration and noise control of the motor, the overall balance effect of the rotor will not be affected by the later installation of the fan and maintains the original good balance state; as for the motor noise can be reduced overall through the low-noise design of the fan.
(6) From the structural analysis of the motor, because of the mutual independence of the fan and the motor body, it is relatively easier to maintain the motor bearing system or perform disassembly and inspection than a motor with a built-in fan.
However, from the analysis of the manufacturing cost, the cost of an independent fan is significantly higher than that of a fan built in an industrial frequency motor. However, for inverter motors operating in a wide speed range, an axial flow fan must be installed.
Figure 3: Inverter motor.
2. Inverter Motor Cooling Fan Control Method (Making Your Equipment More Intelligent)
Cooling fan control technology is a very important technology in modern industry. It can improve the heat dissipation efficiency of the equipment and ensure the safe operation of the equipment. The implementation of cooling fan control techniques requires mastering the following points:
1. Set appropriate temperature control parameters
Temperature control parameters are key to cooling fan control. Appropriate temperature control parameters need to be set according to the heat dissipation requirements of the equipment and the ambient temperature. Set upper and lower temperature limits, temperature change rate, etc.
2. Select the appropriate fan type and quantity
Different types and numbers of fans can provide different cooling effects. The appropriate fan type and number need to be selected based on the cooling needs and space constraints of the device. Selecting a high-speed fan can improve cooling efficiency, but will increase noise and power consumption.
3. Realize intelligent control
Intelligent control can adjust the fan speed in real time according to the working status of the device and the ambient temperature, improving heat dissipation efficiency and energy saving effects. When the device is idle, the fan speed can be reduced to save energy.
Mastering these skills can improve the intelligence level of fans, improve production efficiency, reduce energy consumption, and ensure the safe operation of equipment.
Figure 4: Cooling fans.
3. Precautions for Selecting and Using Inverter Motor Cooling Fans
It should be noted that when selecting an inverter motor cooling fan, it is necessary to comprehensively consider factors such as the motor's power, speed, and dimensions, and ensure that the fan's air volume, static pressure, noise and other parameters meet the motor's cooling requirements.
At the same time, for some inverter motors that need to be used in harsh environments, such as high temperature, high humidity, corrosion, etc., it is necessary to choose a cooling fan with a high protection level, suitable materials and structure, to ensure the safety and reliability of the equipment.
Figure 5: Matching inverter motor for water pump.
In addition, in practical applications, in order to ensure the effectiveness of the inverter motor cooling fan, the following points need to be noted:
1. Number of cooling fans: For high-power inverter motors, multiple cooling fans are usually required to work together to ensure the cooling effect.
2. Control of air volume and air pressure: In order to ensure the effectiveness of the cooling fan, the air volume and air pressure need to be adjusted according to actual needs to ensure sufficient air volume and static pressure while minimizing noise and energy consumption.
3. Maintenance of the cooling fan: Long-term use of the cooling fan may cause problems such as dust and dirt, affecting the cooling effect of the fan, so regular cleaning and maintenance are required.
To sum up, the inverter motor cooling fan plays an important role in the normal operation of the inverter motor, which can ensure the cooling effect of the motor, thereby extending motor life and improving motor efficiency. Therefore, various factors need to be carefully considered when purchasing and using cooling fans to ensure the reliability and safety of the equipment.
