Drive a large TEC module in a liquid cooling loop that needs to both cool and heat, with tight temperature regulation and remote access for monitoring.
The Solution
Full H-bridge with high-side and low-side current sensing for accurate bidirectional power measurement. The WiFi-enabled MCU runs a PID loop and serves a simple web interface for setpoint control and temperature logging. The power stage uses 2oz copper with wide traces to keep resistive losses and thermal rise under control at the current levels this TEC draws.
Results
Regulates to ±0.1°C at steady state. The web interface lets lab technicians monitor and adjust coolant temperature remotely.
How the loop is closed
Measured both ways. Current sensing on both sides of the bridge gives an accurate power reading in heating and cooling, the MCU runs the PID loop, and the same chip serves the web page technicians use to watch and adjust the coolant.Why the current is measured on both sides. A TEC pumps heat in proportion to its current but also heats itself with the square of it, so past a certain current it pumps less, not more. The same module heats the loop when the current reverses. Sensing the current on both the high and low side lets the firmware keep the module in its efficient region and know the real power in either direction.
Have a Similar Challenge?
TEC drivers with PID control and remote monitoring are part of the regular work.
