CN202579259U - Fan rotation speed control circuit with pulse width modulation (PWM) and temperature control functions - Google Patents

Abstract

The utility model mainly discloses a fan rotation speed control circuit with pulse width modulation (PWM) and temperature control functions, which has dual PWM and temperature control functions. The fan rotation speed control circuit comprises a temperature duty ratio generation module, an AND gate, a filtering module, a comparator and a drive module, wherein the temperature duty ratio generation module generates a duty ratio signal which is linearly changed with temperature; the AND gate carried out AND operation on the temperature duty ratio and the PWM signal; the filtering module converts the logic output of the AND gate into a simulation level; the comparator compares the simulation level which is output by the filtering module with a triangular wave, so an output duty ratio signal is obtained; and the drive module drives a fan coil according to the output duty ratio signal to control the fan rotation speed. A fan which adopts the technical scheme has the advantages of low noise and high efficiency.

Description

A kind of have PWM and a temperature controlled circuit for controlling speed of fan

Technical field

The utility model relates to electronic technology field, and special and a kind of to have a PWM relevant with temperature controlled circuit for controlling speed of fan.

Background technique

Fig. 1 is the rotating speed control framework of existing technology; Temperature dutycycle generation module generates one and is the temperature duty cycle signals of linear change with temperature; This temperature duty cycle signals and pwm signal are through carrying out and computing with door; Obtain exporting signal, through driver module drive fan coil, the control rotation speed of the fan.

The schematic representation of each signal in Fig. 2 existing technology, the first behavior temperature duty cycle signals wherein, the second behavior pwm signal, the third line are and door output signal that fourth line is the current waveform of fan loop.

With the output signal of door be the mixed frequency signal of pwm signal and temperature duty cycle signals; Can be because mudulation effect cause on fan loop producing an approximate current component (referring to Fig. 2 fourth line) that changes by sinusoidal rule, the frequency of this current component is frequency poor of pwm signal and temperature duty cycle signals.This current component can cause coil and rotor to produce vibrations.Because two frequencies are more approaching usually, so its difference must fall into audiorange, the noise that causes the fan generation to hear, promptly so-called electromagnetism sound.This is first problem of the frequency generation of pwm signal and temperature duty cycle signals.

In addition; When the dutycycle sum of the dutycycle of pwm signal and temperature duty cycle signals greater than 1 the time (seeing Fig. 2 the third line); In the stage of the phase shifting of pwm signal and temperature duty cycle signals, the switch number of times of phase becomes (zone of Fig. 2 the third line setting-out) 4 times by original 2 times weekly.Extra switch motion brings bigger switching loss, has reduced the efficiency of fan.This is frequency different second problems bringing of pwm signal with the temperature duty cycle signals.

Under the prerequisite that does not change framework; Make the frequency of electromagnetism sound be higher than the audibility range upper limit of people's ear, must oscillator frequency be transferred to PWM frequency and audio frequency upper limit sum, promptly more than the 43KHz; But the frequency increase can cause switching loss to increase thereupon, reduces the efficiency of fan; And the decline of the extra efficiency that switch motion brought is inevitable.

In order to address the above problem, the inventor designs a kind of PWM of having and temperature controlled circuit for controlling speed of fan, and this case produces thus.

The model utility content

The main purpose of the utility model provides a kind of PWM of having and temperature controlled circuit for controlling speed of fan, can eliminate the electromagnetism sound of former framework, and improves the efficiency of fan.

In order to achieve the above object, the utility model is realized through following technological scheme:

A kind of have PWM and a temperature controlled circuit for controlling speed of fan,

Comprise a temperature dutycycle generation module, generate one and be the duty cycle signals of linear change, be connected to and one of them input end of door with temperature;

Comprise a pwm signal, be connected to and another input end of door;

Comprise one with door, connect temperature dutycycle generation module and pwm signal, temperature dutycycle and pwm signal are carried out and computing;

Comprise a filtration module, connect an output signal that produces with door, will convert a stable analog level with the logic output of door into, simultaneously with the filtering of electromagnetism voice frequency;

Comprise a comparator, its input end connects the analog level and the pyramidal wave of filtration module output respectively, both is compared obtain exporting signal;

Comprise a driver module, its input end connects the output terminal of comparator, and its output terminal connects fan loop, the control rotation speed of the fan.

Described filtration module is RC wave filter, SCF or temporal filtering device.

After adopting such scheme, the utlity model has many beneficial effects:

1, low noise is because the frequency of electromagnetism sound by filtering, therefore no longer produces the electromagnetism sound.

2, high energy efficiency, because filtration module is exported a stable analog level, output switch number of times can not surpass 2 times in each pyramidal wave cycle, eliminated extra switch motion, so efficiency is higher.

Description of drawings

Fig. 1 is a circuit diagram of the prior art;

Fig. 2 is the schematic representation of each end signal in the existing technology;

Fig. 3 is the circuit diagram of the utility model preferred embodiment;

The circuit diagram of the filtration module that Fig. 4 realizes for the method that adopts RC filtering in the utility model preferred embodiment;

Fig. 5 is the schematic representation of each end signal in the utility model preferred embodiment.

Embodiment

In order to make those skilled in the art person better understand the present invention program, will combine accompanying drawing below, the technological scheme among the utility model embodiment is carried out clear, complete description.

A kind of have PWM and a temperature controlled circuit for controlling speed of fan, comprise temperature dutycycle generation module 1, pwm signal 2, with door 3, filtration module 4, comparator 5, pyramidal wave 6, driver module 7.

Temperature dutycycle generation module 1, pwm signal 2 are connected respectively to two input ends with door 3; Temperature dutycycle generation module 1 generates a duty cycle signals that is linear change with temperature and passes through with pwm signal and carry out and computing with door 3, produces one and exports signal.

Be connected filtration module 4 with the output terminal of door 3, will convert a stable analog level into the output of the logic of door through filtration module 4, simultaneously with the filtering of electromagnetism voice frequency.

The output terminal of filtration module 4 and pyramidal wave 6 are connected respectively to two comparison input ends of comparator 5; Comparator 5 compares the analog level of filtration module 4 output and pyramidal wave 6 and obtains exporting signal; This signal is connected on the driver module 7; Through driver module 7 drive fan coils, the control rotation speed of the fan.

The key point of this patent is filtration module 4, can adopt the continuous filtering mode, and filtering realizes like RC; Also can adopt modes such as SCF, temporal filtering device to realize.

The filtration module 4 that a kind of method of the RC of employing filtering of having disclosed Fig. 4 realizes.Export a stable analog level with the logical signal of door 3 outputs through the RC wave filter.Resistance 309 and 310 bandwidth of setting wave filter of electric capacity.

The bandwidth of RC wave filter can be set as required, reasonably sets the purpose that this bandwidth can reach filtering electromagnetism sound.Among Fig. 5, the temperature duty cycle signals that the first behavior temperature dutycycle generation module 1 produces; The second behavior pwm signal 2; The third line is a comparator output signal, and fourth line is the current waveform of fan loop.Shown in the fourth line among Fig. 5, the initial conditions same with the framework in the background technique, the sine-wave current that output current superposeed so just can solve first problem in the background technique by filtering.

Because the output voltage of wave filter changes slowly; Therefore output switch number of times can not surpass 2 times (referring to Fig. 5 the third line) in each pyramidal wave cycle; Avoided switch motion extra in the former framework; Loss reduces, so the efficiency of fan is higher, so both can solve second problem in the background technique.

In sum, the utlity model has the advantage of low noise, high energy efficiency.

The above only is the preferred embodiment of the utility model, is not to any pro forma restriction of present embodiment.Anyly be familiar with those skilled in the art; Do not breaking away under the technological scheme scope situation of the present invention; Can utilize the method and the technology contents of above-mentioned announcement that the utility model is made many possible changes and modification; Perhaps be revised as the equivalent embodiment of equivalent variations, all still belong to the scope of the present invention's protection.

Claims (2)

1. one kind has PWM and temperature controlled circuit for controlling speed of fan,

Comprise a temperature dutycycle generation module, generate one and be the duty cycle signals of linear change, be connected to and one of them input end of door with temperature;

Comprise a pwm signal, be connected to and another input end of door;

Comprise one with door, connect temperature dutycycle generation module and pwm signal, temperature dutycycle and pwm signal are carried out and computing;

It is characterized in that:

Comprise a filtration module, connect an output signal that produces with door, will convert a stable analog level with the logic output of door into, simultaneously with the filtering of electromagnetism voice frequency;

Comprise a comparator, its input end connects the analog level and the pyramidal wave of filtration module output respectively, both is compared obtain exporting signal;

Comprise a driver module, its input end connects the output terminal of comparator, and its output terminal connects fan loop, the control rotation speed of the fan.

2. a kind of have PWM and temperature controlled circuit for controlling speed of fan as claimed in claim 1, it is characterized in that: described filtration module is RC wave filter, SCF or temporal filtering device.

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