openinverter forum

I have build PWM controller for the Nissan Lead Cooling Fan and Nissan Leaf Coolant Pump. This controller can read the inverter and motor coolant temperature from the CANBUS on a Nissan Leaf stack. I am trying to determine optimal fan speeds and pump flow rate to optimize inverter coolant and motor coolant efficiency, I will probably use rate of temperature change and target tempature. Does anyone know the optimal operating temperature for these components? Has anyone already tackled this issue already?

There's some info for the pump in the wiki but I'm not aware of anyone combining things and sharing it.
Are you doing ac too? This will also need fan control.
Heat may have a different temp range unless you are doing electric air.

I have the pump and fan controllers controlled with an Arduino via PWM. The Ardunio also gets inverter and motor temp from the canbus. It uses a PID library to control the speed of the fan and pump for target temperature of whichever is greater, the motor or the inverter. I plan to only cool the PDM, motor and inverter with this coolant system. I will try to use the PTC heater from the leaf for heating and ac is not in the plan yet. If the PDM, inverter and motor can operate at a higher temp, I may pipe in the coolant loop to the existing Porsche heater coil. But I would need to understand ideal operating tempature for the PDU, motor and inverter. This is why i am looking for the optimal temp.

In the end if you are running motor and inverter and pdm in the same loop you just want it all as "cool" as possible. Below 45-50C should be the target.

With the waterpump there will be an upper limit above which coolant will be trying to flow too fast and thus create too much pressure loss and becomes in efficient and removing heat vs pump power.

A cooling fan you want to ramp up as the coolant to ambient delta increases. Increasing cooling fan speed when ambient air is not far below coolant temp will not really yield a lot of benefit.

Luckily EVs are very efficient so most just get away with a simple pump running at a fixed speed and having a fan kick on at 35-45C.

Biggest issue is tuning the system, as it requires heat input, vehicle speed to be consistent which is not really feasible during road testing.

Suggested strategy:
1. Start off at lowish flow and have it ramp based on system temp as you suggest
2. Measure pressure after the pump and find the point which it starts to rise sharply and use this as you max pump speed.
3. Have the fan come on at 35C coolant and ramp it up to max at lets say 50-55C.

None of the heat in your drivetrain is usefull for the cabin, unless you use a heatpump system.

You could look at adjusting pump pwm with coolant temp reference from your hottest device.
The motor itself would be ideal to be cool, inverter too. But the transmission / differential oil will be better warm / hot.

Here's a little real world sampling point of a Nissan Leaf motor cooled without fan, a tiny radiator and bottom of the range waterpump:

@bapshago ~ what is the basic PWM frequency you use with the Leaf cooling fan module?

bapshago wrote: ↑Thu Aug 14, 2025 9:21 pm I have the pump and fan controllers controlled with an Arduino via PWM. The Ardunio also gets inverter and motor temp from the canbus. It uses a PID library to control the speed of the fan and pump for target temperature of whichever is greater, the motor or the inverter. I plan to only cool the PDM, motor and inverter with this coolant system. I will try to use the PTC heater from the leaf for heating and ac is not in the plan yet. If the PDM, inverter and motor can operate at a higher temp, I may pipe in the coolant loop to the existing Porsche heater coil. But I would need to understand ideal operating tempature for the PDU, motor and inverter. This is why i am looking for the optimal temp.

See here if you can get your info on page 12...
https://www.energy.gov/sites/prod/files ... 2013_o.pdf
Looks like Leaf motor is a beast, But i wouldnt count on motor heating up cabin in winter. There is some temperature but no real kW...

@danjulio 980 using pin 33 on an esp32 using the ledc api.