Question:
According to which rough formula can the power losses in partial load occurring in the drive controller be calculated roughly in order to dimension e. g. the required power of a cooler?
Answer:
Generally, the occurring power loss of the drive controllers consist of a constant and variable part.
The constant part is determined by the control module and, if required, by the device's fan.
The variable part occurs in the power stage and is laod-dependent (current dependent):
- Power loss = Pconst + (PV - Pconst) * IMot / IN
Pconst is the constant part of the power loss. Following values are possible:
- 9300: 60 W (0.37...11 kW), 100 W (15...22 kW), 150 W (30...45 kW), 200 W (55...75 kW)
- 8200 vector: 10 W (BF1 + BF2), 22 W (BF3), 30 W (BF4), 45 W (BF5), more power see 9300
Pv is the total power loss to be eliminated. The values can be taken from the operating instructions:
- 9300: Chapter ratings (power loss)
- 8200 vector: Chapter ratings (power loss)
IMot: actual effective motor current, earth leakage currents via the shield included.
IN: rated output current dependent on the selected switching frequency of the inverter.
Note:
This is an approximation formula for rough estimation of the occurred thermal power losses.
Please consider that e. g. the height of the mains voltage has also influence. Especially in case of long motor cables the occurring capacitive leakage currents are to be considered by addition to the motor current
IMot.
The influence of the selected switching frequency of the inverter is considered by adaptation of the rated output current, which can be found inside the operating instructions.
