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[Fan types and features] PWM Controller
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PWM control function is a control function that uses "Pulse Width Modulation" and externally controls the fan rotation speed by changing the duty ratio of the pulse signal input between the control terminal and GND.
The airflow can be adjusted to the optimum level when needed in response to changes in the heat generation (load) of the equipment, enabling efficient cooling, which is effective in reducing power consumption and equipment noise.
*Explanation using our products as examples
PWM fan changes its rotation speed according to the duty ratio of the input PWM signal, as shown in the following characteristics.
Users can set the rotation speed themselves, and operate at the required rotation speed when needed.
In addition, the rotation speed in response to the PWM signal can be customized to suit user requirements, allowing the fan to be stopped or rotated at a slow speed, for example.
The following is an example of the characteristics of a fan that stops when the PWM duty cycle is 0%. Specifications vary by model, so please contact us for details.
The dashed lines or no lines on the PWM duty vs. rotation speed characteristic graph indicate areas where the rotation speed is unstable. (In the above figure, PWM duty cycle: 20% or less)
To achieve PWM control, it was necessary to design a new PWM circuit. By using this product, you can use PWM fan without designing a new circuit, contributing to lower power consumption and noise levels in your equipment.
It can be used with a common power supply for fans with a rated voltage of 12 V/24 V/48 V.
Up to four PWM fan can be connected and used.
Voltage control, variable resistor control, and thermistor control are possible.
We will introduce an example of applying our PWM fan.
By combining a thermistor that detects the air temperature and component temperature above the equipment with a PWM control circuit, PWM fan is controlled in response to temperature changes in the equipment.
Because it is controlled by digital input (PWM signal), it can control multiple fans simultaneously, regardless of fan type or input voltage.
As shown in the figure, by installing multiple products with different PWM characteristics inside the equipment and controlling them simultaneously, the required air volume can be adjusted according to changes in the equipment's condition, which is effective in reducing power consumption and noise levels of the equipment.
| mode | PWM Duty | Fan A | Fans B and C |
| Full operation | 100% | 5000 min-1 | 5000 min-1 |
| Normal operation | 60% | 3500 min-1 | 4000 min-1 |
| Standby (energy saving) | 0% | Stop | 1500 min-1 |
Company O is a manufacturer and seller of security-related equipment, including security cameras. The company had recently embarked on the development of a high-quality full HD security camera system for outdoor installation, but had some issues with heat management inside the device. T, the leader of Company O's design and development team, said the following:
"The new camera system we were developing was equipped with a high-performance image processing engine, which caused the inside of the device to get quite hot. At first, we considered using a fan with a high airflow rate, but the high rotation speed caused vibrations and blurred the images. A fan with a lower rotation speed reduced the vibrations, but the airflow was insufficient to reduce the heat." (Mr. T)
As Mr. T continued to gather information, he became interested in the "PWM control" function.
"We found that if the fan had PWM control function, we could control the fan speed by inputting a pulse signal. We hoped that this function would also solve the issue of noise. Because the security camera system will be operating outdoors 24 hours a day, we thought that we could reduce the noise by lowering the rotation speed at night, when the temperature is relatively low. We therefore considered developing a PWM control circuit in-house, but the man-hours required to design a new board and the evaluation period were longer than we expected, so we gave up on the idea." (Mr. T)
Mr. T continued to gather information and found a solution to these issues by consulting a sales representative at SANYO DENKI CO., LTD..
"When we first asked about the vibration of the fan, we were told that we could reduce the vibration simply by switching to a SANYO DENKI CO., LTD. fan. We were interested to hear the specific details, such as how they achieved low vibration through structural innovations that reduce vibration and balancing during the manufacturing process, as well as high assembly precision. Security camera systems are equipped with components that are sensitive to heat, so cooling fans play a very important role. We had been very concerned about the balance between image quality and performance in the product we were developing, but we expected that SANYO DENKI CO., LTD. 's DC Cooling Fan would provide sufficient cooling performance and overcome the vibration issues." (Mr. T)
Additionally, because the proposed fan had PWM control function, we consulted about developing a controller circuit, which we had initially given up on, and a SANYO DENKI CO., LTD. sales representative suggested a board-type "PWM Controller."
"I was surprised at how easy it is to use the San Ace PWM Controller, just by connecting it to a fan. A temperature sensor called a thermistor automatically controls the fan speed according to the detected temperature inside the device, reducing noise by an additional 30db at night when more airflow is not needed," said Mr. T.
Source: SANYO DENKI CO., LTD. Cooling System General Catalog Technical Information
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