Megmeet inverter - over-temperature protection for common fault analysis and treatment of inverter

1. Over-temperature protection of inverter and its necessity

The temperature protection function of the inverter is an indispensable condition to ensure the stable operation of the inverter; In the main circuit power device of the inverter, the rectifier bridge and the inverter bridge are semiconductor power devices, which cannot exceed the allowable working range of the device itself due to the limited operating temperature characteristics of the semiconductor device itself; In addition, the temperature is not allowed to be too high in the electronic circuit of the inverter. If the inverter is overheated, it may lead to the degradation of the performance of the whole machine, the acceleration of the aging of the device, and even the explosion of the machine, so the temperature protection link is essential.

2. Inverter temperature detection

(1) Usually the inverter should detect the temperature of the air inlet, which can be understood as the ambient temperature; The radiator temperature near the rectifier bridge, the radiator temperature near the inverter bridge, and the power are not exactly the same at different detection points.

(2) At the beginning of the research and development of the inverter, it has passed the check of thermal balance, that is, the heat generation of the inverter under the rated load is balanced with the heat dissipation of the inverter, that is to say, the inverter works under normal working conditions, and the inverter will not overheat.

3. Over-temperature caused by improper design selection

(1) The capacity of the inverter does not match the power of the driven motor, resulting in a large operating current, which ultimately leads to the over-temperature protection of the inverter.

(2) The inverter selection margin is insufficient, and the load fluctuation and overload repetition cycle are not fully considered.

(3) The inverter is used in high-altitude areas, and the degrading use of the inverter is not fully considered, because the air is thin in high-altitude areas, which will lead to the poor heat dissipation effect of the inverter. (Of course, the temperature at high altitude is lower than that at low altitude, which is one aspect of the heat dissipation of the inverter).

(4) The long-term low-frequency operation of the inverter leads to the increase of the switching loss of the inverter itself, resulting in the overtemperature of the inverter, in this case, the operating frequency of the inverter needs to be increased, and the reduction ratio of the transmission mechanism is increased.

(5) For high ambient temperature, the heat dissipation capacity of the inverter is poor, and it is necessary to consider the installation of air conditioning in the inverter cabinet for heat dissipation, or the overall installation of air conditioning in the electric control room.

4. The over-temperature problem caused by the inverter itself

(1) The temperature detection circuit is abnormal, resulting in overtemperature.

(2) The temperature sensor is damaged, resulting in overheating.

(3) The cooling fan of the inverter itself is damaged, and the power supply of the DC24V fan is abnormal, resulting in the overtemperature of the inverter.

(4) For high-power inverters, the voltage of the power supply transformer winding tap of the cooling fan is not suitable, resulting in the low speed of the fan, which cannot meet the demand of normal ventilation.

For high-power inverters, the fuse of the power supply transformer of the cooling fan is blown and the cooling fan does not rotate.

5. Over-temperature caused by improper cabinet formation

(1) The installation space of the inverter in the cabinet is not fully considered, and sufficient heat dissipation space needs to be left in accordance with the hardware manual of the inverter.

(2) The ventilation volume of the inverter cabinet is insufficient, resulting in the heat generated by the inverter cannot be taken away by the air.

(3) The structure of the inverter cabinet is unreasonable, usually the lower part of the inverter cabinet is cold air entering, and the top is hot air discharge, and the air path is generally designed in accordance with the natural flow direction of air.

Multiple inverters are installed in the cabinet, and the inverters are arranged up and down, resulting in the over-temperature failure of the inverters above.

6. Over-temperature caused by improper use

(1) In the installation environment of the inverter, there is a large amount of oil, gas and dust in the air, and after working for a long time, it is equivalent to coating a layer of oil on the surface of the radiator of the inverter, which is very unfavorable for heat dissipation. It is necessary to install filter cotton at the air inlet of the inverter cabinet.

(2) The inverter cabinet is usually installed on the cable trench, if the bottom of the cabinet is not blocked, the dust, installation debris and other small things in the cable trench are easy to be sucked into the inverter, resulting in the blockage of the heat dissipation air duct, and the heat can not be dissipated, which eventually leads to the overtemperature of the inverter.

(3) The inverter is installed in the wrong direction, which may also lead to overtemperature of the inverter, and the general inverter requires vertical installation, which is conducive to heat dissipation.

(4) The switching frequency of the inverter is set too high (P1800 parameter), which leads to the increase of its own switching loss, and may also lead to the overtemperature of the inverter.

Megmeet inverter - over-temperature protection for common fault analysis and treatment of inverter

Megmeet inverter - over-temperature protection for common fault analysis and treatment of inverter

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