# 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.