Advanced Cooling Circuit Design¶
The power electronics of the MC110 will produce heat and its temperature will increase. To prevent overheating, the heat will be absorbed by a liquid coolant according to the following equation:
\(Q=m \cdot c \cdot (T_{out}  T_{in})\)
\(Q\): heat produced by one single MC110.
\(m\): coolant mass flow.
\(c\): coolant specific heat.
\(T_{out}\): temperature of the coolant at the output of the coldplate and at the input of the radiator.
\(T_{in}\): temperature of the coolant at the input of the coldplate.
\(Q\) is assumed to be completely absorbed by the coolant, this assumption is considering the worst case scenario (adiabatic environment, which does not help at all).
The value of \(Q\) depends strongly on the switching frequency, input voltage (from battery) and motor power (hence intensity consumption). It can be obtained from the following tables, which assume an input coolant of water at 30 ºC (\(T_{in}\)) and 6 l/min:
Q for 10 kHz switching frequency (W) 

Motor power (kW) 
Battery voltage 

800 V 
550 V 
100 V 

15 
200 
250 
950 
30 
400 
450 
* 
45 
600 
750 
* 
60 
850 
1000 
* 
75 
1100 
1350 
* 
95 
1350 
1700 
* 
110 
1750 
2200 
* 
Q for 16 kHz switching frequency (W) 

Motor power (kW) 
Battery voltage 

800 V 
550 V 
100 V 

15 
300 
300 
1000 
30 
550 
600 
* 
45 
850 
950 
* 
60 
1150 
1300 
* 
75 
1500 
1750 
* 
95 
2050 
2250 
* 
110 
2550 
3000 
* 
Q for 22 kHz switching frequency (W) 

Motor power (kW) 
Battery voltage 

800 V 
550 V 
100 V 

15 
350 
350 
1050 
30 
700 
750 
* 
45 
1100 
1200 
* 
60 
1550 
1650 
* 
75 
2050 
2250 
* 
95 
2650 
* 
* 
110 
* 
* 
* 
Warning
*: These situations involve an intensity higher to 250 A or overheating.
Once the heat transfer has been defined, the radiator can be chosen according to the required heat transfer capacity. Considering that each radiator dissipates the heat of several motor controllers.
\(H = Q \cdot n/(T_{out}  T_{amb})\)
\(H\): heat transfer capacity.
\(n\): number of motor controllers for the radiator.
\(T_{amb}\): ambient temperature.
\(H = \frac{Q \cdot n}{T_{in} + Q/(m \cdot c)  T_{amb}}\)
Applying the previous equation to one MC110 obtains the tables of the Simplified Cooling Circuit Design.