Degree Controls has released theC-600, which controls & modulates fan RPM based on measuring the real-time air velocity. The company touts this as an ideal way to ensure the linear air velocity determined during system design is available and maintained in the actual system, while external factors like filter clog, inlet blockage, or different populations of components and cabling affect the air flow rate.
The user programs the desired air velocity set point at the sensor location, which is derived empirically during the prototyping or analysis stage of the product. The sensed air velocity is compared to the set point in order to generate a PWM control input to the fan. In this fashion, the C-600 increases and decreases fan RPM in order to maintain the desired air velocity.
The controller also communicates to a host system by means of I2C or UART, and can provide the air velocity, air temperature, and PWM signal being generated, all in real time.
Should your cooling fan(s) be unable to generate the desired flow requirement, then the controller would initiate a low-flow alarm to the system. Because the C-600 also measures air temperature, a second configurable over-temp alarm can also be initiated to the system. If, within a system, there is access to monitor fan RPM, it is possible to predict filter clog by comparing the fan RPM to the sensed air velocity over time.
Advanced users will also implement the C-600 to control fan speed using a temperature set point instead of an air velocity set point. In this case, the C-600 will modulate fan RPM to maintain the desired temperature using a tunable PI loop.
This controller is extremely compact (less than 1 sq in.), using 7 pins on standard 0.1” centers. The component is mounted directly to the PCB, wherever air velocity or temperature is most critical in the system.
December 16, 2009