A method for switching forward and reverse directions and starting a fan against the wind

Abstract

The present invention provides a method for switching between forward and reverse rotation and starting a fan against wind, and relates to the field of fan control technology. After the fan is started, fault detection is performed. If a fault is found, the fault handling logic is entered. If there is no fault, a PWM signal is detected; whether the PWM signal is at a set speed regulation frequency is detected. If so, the fan performs reverse operation, and if not, the fan performs forward operation. The benefit of the present invention is that the fan direction is determined by identifying the frequency of the speed regulation signal. When the speed regulation frequency is in a lower frequency band such as 5Hz-50Hz, the fan will reverse at a fixed speed. When the speed regulation frequency is not within the range of 5Hz-50Hz in this low frequency band, the fan will rotate forward, and the forward rotation speed is controlled according to the duty cycle of the speed regulation signal. When the speed regulation signal is at a high level, the fan will rotate forward at full speed. When there is no speed regulation signal, the fan stops running; thus, the dust removal function or regular automatic dust removal can be realized as needed, thereby improving the use efficiency of the fan and extending the service life of the fan.

Description

Technical Field

[0001] The invention relates to the technical field of fan control, and in particular to a method for switching between forward and reverse rotations and starting a fan against wind. Background Art

[0002] A fan is a machine that relies on input mechanical energy to increase gas pressure and discharge gas. It is a driven fluid machine. Generally, a DC fan has only one direction of rotation, and can only control the speed of the fan, but cannot reverse. When the fan is placed outdoors for use, in a harsh dusty environment, after years of accumulation, the surface of the fan and the blades will be covered with dust, causing the fan load to increase and the blades to deform, thereby affecting the use effect of the fan and even the life of the fan. In response to this problem, the present invention provides a fan that can rotate both forward and reverse. The fan can rotate forward or reverse according to the needs of the entire machine, thereby avoiding dust accumulation on the blades due to the fan having only one direction of rotation, and enabling the fan to have the ability to automatically remove dust. Summary of the invention

[0003] The present invention overcomes the shortcomings of the prior art and provides a method for forward and reverse switching and starting a fan against the wind, which has the characteristics of fast response time, high efficiency and long service life.

[0004] In order to solve the above technical problems, the present invention is achieved through the following technical solutions:

[0005] A method for switching forward and reverse rotation and starting a fan against wind, for a DC fan with PWM speed regulation, controls the forward and reverse rotation of the fan according to the frequency of the speed regulation signal; comprising the following steps:

[0006] S1. Start, after the fan is started, fault detection is performed. If a fault is found, the fault processing logic is entered. If there is no fault, the PWM signal is detected:

[0007] S2, detect whether the PWM signal is at the set speed regulation frequency, if yes, the fan works in reverse and enters the following step S3 for execution; if no, the fan works in forward direction and enters the following step S6 for execution;

[0008] S3, check whether it is in a stationary state, if yes, the fan reverses and starts running; if no, further check whether it is in a reverse state, if yes, it indicates that it is reversing, and the fan continues to reverse; if no, check whether it is in a normal running state, if yes, enter step S4, if no, enter step S5;

[0009] S4, then execute the shutdown operation, and detect whether the forward speed is less than the set value, such as less than 2000RPM (the actual speed is set at 30% of the maximum speed, such as 6000RPM at full speed, and the set value is 2000RPM) or whether the extension time exceeds the set time, such as 1.5 seconds (the software speed adjustment is 1 second to 10 seconds, and the optimal value is 1.5 seconds); if so, short-circuit braking is performed, and then the fan speed is detected to be less than 235RPM. If so, the fan can be reversed and started to run. If not, short-circuit braking is continued, and the fan speed is detected again, and the cycle is repeated in sequence until the fan speed is detected to be less than 235RPM, and the fan can be reversed and started to run;

[0010] S5, short-circuit brake for at least 1 second, then detect whether the fan speed is less than 235RPM, if so, the fan can be reversed and started, if not, continue to short-circuit brake, then detect the fan speed, cycle in sequence, until it is detected that the fan speed is less than 235RPM, then the fan can be reversed and started;

[0011] S6, check whether it is in a stationary state, if yes, the fan starts running in forward direction; if no, further check whether it is in a forward state, if yes, it indicates that it is running forward, and the fan keeps running in forward direction; if no, check whether it is in a normal running state, if yes, go to step S7, if no, go to step S8;

[0012] S7, then execute the shutdown operation, and detect whether the reverse rotation speed is less than 2000RPM or whether the extension time exceeds the preset time; if so, perform short-circuit braking, and then detect whether the fan speed is less than 235RPM. If so, the fan can start running in the forward direction. If not, continue to perform short-circuit braking, and then detect the fan speed, and cycle in sequence until it is detected that the fan speed is less than 235RPM, then the fan can start running in the forward direction;

[0013] S8, perform short-circuit braking, and then detect whether the fan speed is less than the set value 235RPM. If so, the fan can start running in the forward direction. If not, continue to perform short-circuit braking, and then detect the fan speed, and cycle in sequence until it is detected that the fan speed is less than the set value 235RPM, then the fan can start running in the forward direction.

[0014] Furthermore, the fan direction is determined according to the frequency of the speed regulation signal, and the set speed regulation frequency is 5Hz-50Hz.

[0015] Furthermore, the short circuit braking time is at least 1 second.

[0016] Furthermore, if the fan speed is less than a set value, or the downtime is greater than a set time, a short-circuit braking step is entered.

[0017] Furthermore, the fan speed setting value is 2000RPM and the shutdown time is 1.5 seconds.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The fan of the present invention only needs to give speed regulation signals of different frequencies, and the fan can automatically realize the corresponding forward and reverse rotation and free switching between forward and reverse rotation. The fan forward and reverse rotation response time of the control method is fast and no additional equipment is required; the fan makes the fan blades have forces and vibrations in different directions through forward and reverse switching, so that the dust removal function or regular automatic dust removal can be realized as needed, thereby improving the use efficiency of the fan and extending the service life of the fan. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The accompanying drawings are used to provide a further understanding of the present invention and are used together with the embodiments of the present invention to explain the present invention, but do not constitute a limitation of the present invention. In the accompanying drawings:

[0021] Figure 1 It is the specific control flow chart inside the fan. DETAILED DESCRIPTION

[0022] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0023] like Figure 1 As shown, the present invention discloses a method for switching between forward and reverse rotation and starting a fan against wind. For a DC fan with PWM speed regulation, the forward and reverse rotation of the fan is controlled according to the frequency of a speed regulation signal. This method not only makes the forward and reverse rotation response time of the fan fast, but also does not require additional equipment. The fan causes the fan blades to be subjected to forces and vibrations in different directions through forward and reverse switching, thereby realizing a dust removal function or regular automatic dust removal as needed, thereby improving the use efficiency of the fan and extending the service life of the fan.

[0024] Specifically, the steps include:

[0025] S1. Start, after the fan is started, fault detection is performed. If a fault is found, the fault processing logic is entered. If there is no fault, the PWM signal is detected:

[0026] S2, detect whether the PWM signal is at the set speed regulation frequency, if yes, the fan works in reverse and enters the following step S3 for execution; if no, the fan works in forward direction and enters the following step S6 for execution;

[0027] In this embodiment, the fan direction is determined according to the frequency of the speed regulation signal. If the speed regulation frequency is set to a lower frequency range such as 5Hz-50Hz, the fan will reverse at a fixed speed. When the speed regulation frequency is not within the low frequency range of 5Hz-50Hz, the fan will rotate forward, and the forward rotation speed is controlled according to the duty cycle of the speed regulation signal. When the speed regulation signal is at a high level, the fan will rotate forward at full speed. When there is no speed regulation signal, the fan stops running.

[0028] S3, check whether it is in a stationary state, if yes, the fan reverses and starts running; if no, further check whether it is in a reverse state, if yes, it indicates that it is reversing, and the fan continues to reverse; if no, check whether it is in a normal running state, if yes, enter step S4, if no, enter step S5;

[0029] S4, then the shutdown operation is executed, the MCU will stop the drive signal output, let the fan speed drop, and detect whether the forward speed is less than the set value, such as less than 2000RPM (the actual speed is set at 30% of the maximum speed, such as full speed is 6000RPM, the set value is 2000RMP) or whether the extension time exceeds the set time such as 1.5 seconds (the software speed adjustment is 1 second to 10 seconds, the optimal value is 1.5 seconds); when the fan speed is less than the set value, or the shutdown time is greater than the set time, the short-circuit braking step is entered; if so, the short-circuit braking is performed for at least 1 second, and then the fan speed is detected to be less than 235RPM. If so, the fan can be reversed and started to run. If not, the short-circuit braking is continued for at least 1 second, and then the fan speed is detected, and the cycle is repeated until the fan speed is detected to be less than 235RPM, then the fan can be reversed and started to run; after the short-circuit braking, when the fan basically stops rotating or the speed is lower than a very small speed, the MCU will start the reverse control, and the fan starts to reverse until the corresponding speed is reached;

[0030] S5, short-circuit brake for at least 1 second, then detect whether the fan speed is less than 235RPM. If so, the fan can reverse and start running. If not, continue to short-circuit brake, then detect the fan speed, cycle in sequence, until it is detected that the fan speed is less than 235RPM, then the fan can reverse and start running; similarly, after short-circuit brake, when the fan basically stops rotating or the speed is lower than a very small speed, the MCU will start reverse control, and the fan starts to reverse until it reaches the corresponding speed;

[0031] S6, check whether it is in a stationary state, if yes, the fan starts running in forward direction; if no, further check whether it is in a forward state, if yes, it indicates that it is running forward, and the fan keeps running in forward direction; if no, check whether it is in a normal running state, if yes, go to step S7, if no, go to step S8;

[0032] S7, then the shutdown operation is executed, the MCU will stop the drive signal output, let the fan speed drop, and detect whether the reverse speed is less than 2000RPM or whether the extension time exceeds the preset time; if so, short-circuit braking is performed for at least 1 second, and then the fan speed is detected to be less than 235RPM. If so, the fan can start running in the forward direction. If not, short-circuit braking is continued for at least 1 second, and then the fan speed is detected, and the cycle is repeated until the fan speed is detected to be less than 235RPM, and the fan can start running in the forward direction; after short-circuit braking, when the fan basically stops rotating or the speed is lower than a very small speed, the MCU will start the forward control, and the fan starts to rotate forward until the corresponding speed is reached;

[0033] S8, perform short-circuit braking, and then detect whether the fan speed is less than the set value 235RPM. If so, the fan can start running in the forward direction. If not, continue to perform short-circuit braking for at least 1 second, and then detect the fan speed, and cycle in sequence until it is detected that the fan speed is less than the set value 235RPM, then the fan can start running in the forward direction. Similarly, after short-circuit braking, when the fan basically stops rotating or the speed is lower than a very small speed, the MCU will start forward control, and the fan starts to rotate forward until the corresponding speed is reached.

[0034] In the above steps of this embodiment, the fan speed setting value is 2000RPM, and the shutdown time is 1.5 seconds.

[0035] The innovative point of the present invention is that the fan direction is controlled by the internal control panel through identifying the different frequencies of the speed regulation signal, so that the fan can realize forward and reverse rotation and free switching of forward and reverse rotation at the same time. The fan controls the direction of the fan according to the needs of the whole machine, so as to achieve the effect of automatic dust removal of the fan; only different frequencies of speed regulation signals need to be given, and the fan can automatically realize the corresponding forward and reverse rotation and free switching of forward and reverse rotation. The control method has a fast response time for the forward and reverse rotation of the fan and does not require additional equipment. The fan makes the blades have forces and vibrations in different directions through forward and reverse switching, so that the dust removal function or regular automatic dust removal can be realized according to needs, thereby improving the use efficiency of the fan and extending the service life of the fan.

[0036] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. However, any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for switching forward and reverse rotation and starting a fan against the wind, characterized in that: For a DC fan with PWM speed regulation, the forward and reverse rotation of the fan is controlled according to the frequency of the speed regulation signal; the steps include: S1. Start, after the fan is started, fault detection is performed. If a fault is found, the fault processing logic is entered. If there is no fault, the PWM signal is detected: S2, detect whether the PWM signal is at the set speed regulation frequency, if yes, the fan works in reverse and enters the following step S3 for execution; if no, the fan works in forward direction and enters the following step S6 for execution; S3, check whether it is in a stationary state, if yes, the fan reverses and starts running; if no, further check whether it is in a reverse state, if yes, it indicates that it is reversing, and the fan continues to reverse; if no, check whether it is in a normal running state, if yes, enter step S4, if no, enter step S5; S4, then execute the shutdown operation, and detect whether the forward speed is less than the set value, such as less than 2000RPM (the actual speed is set at 30% of the maximum speed, such as 6000RPM at full speed, and the set value is 2000RPM) or whether the extension time exceeds the set time, such as 1.5 seconds (the software speed adjustment is 1 second to 10 seconds, and the optimal value is 1.5 seconds); if so, short-circuit braking is performed, and then the fan speed is detected to be less than 235RPM. If so, the fan can be reversed and started to run. If not, short-circuit braking is continued, and the fan speed is detected again, and the cycle is repeated in sequence until the fan speed is detected to be less than 235RPM, and the fan can be reversed and started to run; S5, short-circuit brake for at least 1 second, then detect whether the fan speed is less than 235RPM, if so, the fan can be reversed and started, if not, continue to short-circuit brake, then detect the fan speed, cycle in sequence, until it is detected that the fan speed is less than 235RPM, then the fan can be reversed and started; S6, check whether it is in a stationary state, if yes, the fan starts running in forward direction; if no, further check whether it is in a forward state, if yes, it indicates that it is running forward, and the fan keeps running in forward direction; if no, check whether it is in a normal running state, if yes, go to step S7, if no, go to step S8; S7, then execute the shutdown operation, and detect whether the reverse rotation speed is less than 2000RPM or whether the extension time exceeds the preset time; if so, perform short-circuit braking, and then detect whether the fan speed is less than 235RPM. If so, the fan can start running in the forward direction. If not, continue to perform short-circuit braking, and then detect the fan speed, and cycle in sequence until it is detected that the fan speed is less than 235RPM, then the fan can start running in the forward direction; S8, perform short-circuit braking, and then detect whether the fan speed is less than the set value 235RPM. If so, the fan can start running in the forward direction. If not, continue to perform short-circuit braking, and then detect the fan speed, and cycle in sequence until it is detected that the fan speed is less than the set value 235RPM, then the fan can start running in the forward direction.

2. The method for switching forward and reverse rotation and starting a fan against the wind according to claim 1, characterized in that: The fan direction is determined according to the frequency of the speed regulation signal, and the set speed regulation frequency is 5Hz-50Hz.

3. The method for switching forward and reverse rotation and starting a fan against the wind according to claim 1, characterized in that: The short-circuit braking time should be at least 1 second.

4. The method for switching forward and reverse rotation and starting a fan against the wind according to claim 1, characterized in that: If the fan speed is less than the set value, or the downtime is greater than the set time, the short-circuit braking step is entered.

5. The method for switching forward and reverse rotation and starting a fan against the wind according to claim 1, characterized in that: The fan speed setting value is 2000RPM and the shutdown time is 1.5 seconds.

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