New cooling method

The electronic engineering community plays a vital role in the efficient use of energy, providing advanced technology for the extraction, transportation, consumption and control of energy for the benefit of the public. As society pays more attention to energy conservation, the electronic engineering community is playing an increasingly important role. In the semiconductor field, major manufacturers are actively developing ultra-low-power processes to improve work efficiency, but the physical laws stipulate that implementation work will inevitably lead to an increase in transistor junction temperature. Even in ultra-low-power processes, heat builds up, and if it is not heat-dissipated, the transistor burns out. As transistor densities and operating frequencies continue to increase, engineers using integrated devices (including devices that use low-power processes) still need to consider the above issues and take effective measures to dissipate heat. Today, the volume of the device is getting smaller and smaller, and the above problems are more prominent because the power supply device cannot be effectively improved during the development of the process, and at the same time, the power must be supplied with higher efficiency.

Since the heat-dissipating behavior itself requires energy consumption, manufacturers have changed their mindsets and adopted a design concept of “seeing good and collecting”, allowing the cooling level to be determined by specific needs. Traditionally, AC fans have only two states of switching. When the system is on, the fan will normally start and run at full speed. Nowadays, there are a lot of complicated AC fans, which are adjusted according to the specific conditions with different levels of precision control systems. This not only improves the reliability of the fan, extends the life of the fan, but also saves energy and reduces overall system noise.

Fan control

A key first step in new product development is the development of electronically commutated (EC) fans. Since this technology has greatly improved in performance compared to asynchronous motors, it has quickly become a mainstream technology. In particular, EC technology can solve the loss caused by magnetic induction and control the fan operation more effectively.

This technology typically takes the form of a brushless direct current (BLDC) motor. Although controlling BLDC motors requires more circuitry than asynchronous motors, semiconductor technology has evolved to the level of integration of this additional circuitry into the motor casing. This resulted in a series of more powerful compact EC fans, a typical example of which is the ebm-papst recently introduced ACMaxx series.

This series of fans is powered by a common AC power supply. The on-board controller is responsible for adjusting the AC power supply and controlling the brushless DC fan operation. Higher power efficiency and "new replacement" form factor means you can increase output power without having to make adjustments or increase input power.

Adding an internal or external NTC (negative temperature coefficient) thermistor enables speed control to be adjusted to specific needs, and the fan control circuit operates the fan. In this way, we can control the speed and duration of the job, such as turning on the fan only when needed, and turning it off when it is not needed. By introducing an NTC sensor to monitor the temperature, the overall power consumption can be reduced by running the fan only at a rate that maintains sufficient cooling.

The EC fan can save about 30% energy consumption compared to the AC fan, and this number can be further improved after using the controller. However, the use of the controller is not limited to the integrated circuit, but can also be used as an external controller in conjunction with a standard EC fan. Ebm-papst's EC Matrix Temperature Controller is powered directly from the fan power supply and typically requires less than 10mW of power. In addition, NTC thermistors are used to monitor temperature and control fan operation. In addition to ACMaxx, RS now offers two variants of the EC Matrix Temperature Controller. The temperature controller sets the temperature range in advance, and reduces the fan output to 15% when the measured temperature is at or below the minimum value, and raises the output to 100% when it is at or above the highest value. In addition, the product also uses automatic insurance technology to detect NTC open or short circuit conditions.

Similar examples include Pfannenberg's range of thermostats and humidometers that use temperature and relative humidity to adjust fan operation. By adding a relative humidity sensor, the fan maintains the environment above the dew point, thereby increasing control of the components and extending the life of the sensitive electronics.

Fan design

As the fan controller becomes more sophisticated, the design of the fan itself is changing. Manufacturers are adopting a more cautious design concept to develop more efficient fan and blade designs that increase the efficiency of many applications. For example, the backward curved vane fan introduced by emb-papst uses centrifugal technology to wind air into the center of the fan and distribute it laterally. This technology is capable of producing a stronger airflow, especially in an environment where the high back pressure is more pronounced, and is a useful complement to the DC axial fan series. However, although this technology is more advanced than the traditional fan design, in the past it has caused some problems due to the complexity of the installation. Ebm-papst's "Plug and Play" EC card fan series overcomes this difficulty due to its design accuracy. An inlet ring is precisely placed in the impeller eye to maximize the airflow. In addition, the precisely positioned arms prevent noise generated by the over-pitch frequency, and the vibration-isolating mount also prevents resonance in the system.

Demand for filters

The use of forced air to cool sensitive electronic devices necessarily requires the use of filters. In some applications, filters can easily become blocked and fail due to environmental influences. In this case, the cooling capacity of the fan is limited, and the failure may occur quickly, and the service must be serviced regularly. In order to solve this potential risk, Pfannenberg installed alarm devices in various fan products, and recently launched the fourth generation of “filterfan” (filter fan), which uses IP55 compared with previous generations. The air flow in the device is increased by 100%. In addition, with the patented four-corner design, the filter can be accessed without tools, and the cleaning of the filter is easier. After using the product in a very technically demanding sawmill, it was announced that in some cases the regular maintenance service could be postponed to 3 weeks and the life of the fan was prolonged. Other advanced features in the range include reverse-change electrical connections, airflow redirects, patented ventilation and patented filter mat technology that make installation easier.

Despite the continuous development of electronic devices and the adoption of low-energy technologies, the demand for new cooling solutions has always been unavoidable. Although there are many benefits to the forced airflow cooling method, maximum efficiency is often not achieved. As RS introduces the latest technology products developed by leading manufacturers, this problem will be gradually alleviated, and the efficiency of system design can be improved at all levels.