To extend the lifespan of a frequency inverter, heat dissipation must be carefully considered. The failure rate of a frequency inverter increases exponentially with rising temperature, while its lifespan decreases. For every 10-degree Celsius increase in operating temperature, the inverter's lifespan will decrease.
Therefore, we must pay close attention to the heat dissipation problem! When the frequency converter is working, the current flowing through it is very large, and the heat generated by the frequency converter is also large. The damage caused by its overheating cannot be ignored.
Generally, frequency converters are installed in control cabinets. To estimate the heat generated by a frequency converter, we can use the following formula: Heat generated = Frequency converter capacity (KW) × 55 [W]. Here, if the frequency converter capacity is specified for constant torque load (overcurrent capacity 150% * 60s), and if the frequency converter contains DC series reactors or AC series reactors, and is also inside a cabinet, the heat generated will be even higher.
It is better to install the series reactor on the side or top of the inverter. In this case, an estimate can be made: Inverter capacity (KW) × 60 [W]. Since the hardware configurations of various inverter manufacturers are similar, the above formula is applicable to products from various brands.
P.S.: If a braking resistor is included, it dissipates a lot of heat, so its installation location should be isolated from the frequency converter. It can be installed on top of or beside the cabinet. So, how can the heat generated inside the control cabinet be reduced?
When a frequency inverter is installed in a control cabinet, the issue of its heat generation must be considered. The cabinet size needs to be appropriately increased based on the increased heat generation within it. Therefore, to minimize the size of the control cabinet, it is essential to reduce the heat generation within it as much as possible.
If, during inverter installation, part of the inverter's heatsink is placed outside the control cabinet, up to 70% of the inverter's heat can be released outside the cabinet. This is particularly effective for inverters in large spaces, as they generate a significant amount of heat. Furthermore, a protective plate can be used to separate the inverter from the heatsink, preventing the heatsink's dissipation from affecting the inverter itself. This approach also yields excellent results.
Inverter cooling designs are generally based on vertical installation; horizontal placement will reduce heat dissipation. Most inverters with slightly higher output power include a cooling fan. It is also recommended to install a cooling fan at the ventilation opening on the control cabinet. Air inlets must be fitted with filters to prevent dust from entering the control cabinet. Note that both the control cabinet and the inverter's fans are necessary; one cannot replace the other.
In addition, the following two issues also need to be considered regarding heat dissipation:
(1) In areas with an altitude of over 1000m, due to the reduced air density, the cooling exhaust volume of the wooden cabinet should be increased to improve the actual cooling effect. Theoretically, the frequency converter should also be derated, -5% per 1000m.
However, since the load capacity and heat dissipation capacity of frequency converters in the design scheme are generally greater than those in the actual application, it is necessary to consider the actual application. For example, in a 1500m area with regular loads, such as elevator cars, derating is unnecessary.
(2) Switching frequency: The key to the overheating of the frequency converter comes from the IGBT, and the overheating of the IGBT is concentrated in the instant of switching on and off. Therefore, the higher the power switching frequency, the greater the heat generated by the frequency converter. This is the reason why some manufacturers claim that reducing the power switching frequency can increase the capacity.
