Heavy-duty Inverters' Heat Dissipation 

     Frequency converter is a power control device that uses frequency conversion technology and microelectronics technology to control AC motors by changing the frequency of the motor's operating power supply. The frequency converter is mainly composed of rectifier (AC to DC), filtering, inverter (DC to AC), braking unit, drive unit, detection unit, microprocessing unit, etc. The frequency converter relies on the opening and closing of the internal IGBT to adjust the voltage and voltage of the output power supply. Frequency, according to the actual needs of the motor, it provides the required power supply voltage to achieve the purpose of energy saving and speed regulation. In addition, the frequency converter also has many protection functions, such as overcurrent, overvoltage, overload protection, etc.

    Safety precautions for heavy-duty inverters in high-temperature environments:

1. Monitor and carefully record the parameter display on the human-machine interface of the inverter, and report any abnormalities immediately

2. Monitor and carefully record the ambient temperature of the inverter room. The ambient temperature difference should be between -5°C and 40°C. The temperature of the phase-shifting transformer should not exceed 130℃

3. When the temperature is high in summer, ventilation and heat dissipation should be strengthened at the inverter installation site. The surrounding air should be free of excessive dust, salt, acid, corrosive and explosive gases

4. At the same time, since summer is the rainy season, the inverter should prevent rainwater from entering (such as rainwater entering the outlet along the wind tunnel).

5. Arrange regular cleaning. The filter on the inverter cabinet door should be cleaned once a week. If the working environment is dusty, the cleaning interval should be shortened according to the actual situation

6. During normal operation, a piece of A4 paper of standard thickness should be firmly attached to the filter at the air inlet of the cabinet door.

7. The frequency conversion room must be kept tidy and cleaned at any time according to the actual situation on site.

8. The ventilation and lighting visibility of the inverter room must be good, and the refrigeration and ventilation equipment (air conditioners, ventilators, etc.) can work normally.

    In all large power electronic equipment, almost as the temperature increases, the failure rate of the equipment also increases. Therefore, the heat dissipation design of large-scale inverter power supply devices is directly related to the reliability and stability of the equipment. High power and large load inverters often require high reliability. The main form of power electronic equipment failure is thermal failure. According to statistics, more than 50% of electronic thermal failures are caused by temperatures exceeding the rated value. From the perspective of structural design, heat dissipation technology is the key to ensuring the normal operation of the equipment. Since the heavy-duty inverter equipment of Sanke Inverter Company has large power, generally in the megawatt level, it will generate a large amount of heat during normal operation. In order to ensure the normal operation of the equipment, it is necessary to optimize the heat dissipation and ventilation scheme, conduct reasonable design calculations, and achieve efficient heat dissipation of the equipment, which is very necessary to improve the reliability of the equipment.

     Thermal calculation

    In normal operation, the heat sources of large frequency converters are isolation transformers, power units, reactors, control systems, etc. Among them, the heat dissipation design of power devices, power units and power cabinets is the most important. For IGBT or IGCT power devices, the PN junction should not exceed 125°C and the package shell should be 85°C. Research shows that when the temperature fluctuation exceeds ±20°C, the failure rate of the device will increase by 8 times.

     Cooling system design points

(1) Select components and materials with good heat resistance and thermal stability to increase the allowable operating temperature;

(2) Reduce the heat output inside the equipment (device). Therefore, more micro-power devices should be selected, such as low-loss IGBTs, to reduce the number of heating components in circuit design, optimize the switching frequency of the devices, and reduce heat generation;

(3) Using appropriate cooling methods and methods can reduce the ambient temperature and speed up heat dissipation.