A stepless speed controller and a range hood using the same

Abstract

The stepless speed regulation controller comprises a rectifier circuit for taking power from commercial power and rectifying AC voltage of the commercial power into a 100 Hz DC pulsating signal; a zero point extraction circuit for collecting the 100 Hz DC pulsating signal and converting the 100 Hz DC pulsating signal into a zero-crossing pulse signal through resistance R17, R18 and R19 to the b electrode of the triode Q5, and through resistance R13 to the c electrode of the triode Q5; a controller connected with the zero point extraction circuit for collecting the zero-crossing pulse signal, the controller transmitting the zero-crossing pulse signal to a signal modulation circuit, the signal modulation circuit outputting an H bridge control signal; and an H bridge control circuit connected with the signal modulation circuit, the H bridge control circuit converting the H bridge control signal into a driving signal and outputting the driving signal to a motor. The stepless speed regulation controller is used for improving the reliability of the stepless speed regulation controller.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of motor stepless speed regulation controller, and particularly relates to a stepless speed regulation controller and a range hood using the same. BACKGROUND

[0002] The existing stepless speed regulation controller, such as an alternating current fan speed regulator with patent application number CN202010266087, is connected with the alternating current fan, and includes: a zero-crossing detection module for outputting a pulse signal when detecting the zero position of the connected alternating current power supply; a freewheeling module for freewheeling discharge of the fan according to the pulse signal; a control module for outputting a control waveform according to the pulse signal and an external input signal; a chopping modulation module for turning on or turning off the power supply of the fan according to the control waveform; wherein one end of the fan power supply is connected with one path of the alternating current power supply, and the other end is connected with the chopping modulation module. The stepless speed regulation controller uses high-frequency chopping control mechanism to regulate the speed steplessly, outputs a modulation signal with different widths according to the external speed regulation signal requirement, and chops and modulates the input power supply through a chopper tube, which can be used to replace the traditional alternating current fan speed regulator.

[0003] The zero signal extraction method of the above stepless speed regulation controller is that the zero detection module directly obtains the zero-crossing signal from the positive and negative cycles of the commercial power supply. However, the positive and negative cycles of the commercial power supply need to pass through multiple filter capacitors to be collected by the zero-crossing detection module. Since the filter capacitors have the charging and discharging characteristics that cause time delay in signal extraction, the commercial power supply is collected by the zero-crossing detection module after passing through multiple filter capacitors, and the zero-crossing detection module outputs the converted pulse signal. In this process, the delayed pulse signal is easy to cause distortion of the output waveform of the driving circuit.

[0004] At the same time, since the carrier frequency of the stepless speed regulation controller of the fan system in the existing range hood is not high, the noise of the load motor is obvious, which reduces the user experience. SUMMARY

[0005] The present application aims to overcome the shortcomings of the existing stepless speed regulation controller and provide a stepless speed regulation controller with high reliability.

[0006] To achieve the above-mentioned purpose, the present application provides a stepless speed regulation controller, which comprises:

[0007] a rectifier circuit for taking power from the commercial power supply and rectifying the alternating voltage of the commercial power supply into a 100Hz direct current pulsating signal;

[0008] The zero-crossing extraction circuit is used to connect with the rectifier circuit to collect a 100Hz DC pulsating signal. The 100Hz DC pulsating signal passes through resistors R17, R18, and R19 in series to the base of transistor Q5. Resistor R24 ​​connects the emitter and base of transistor Q5 to ground. The on-state voltage of transistor Q5 passes through resistor R13 to its collector. Resistor R13 and transistor Q5 convert the 100Hz DC pulsating signal into a zero-crossing pulse signal.

[0009] The controller is connected to the zero-point extraction circuit to collect the zero-crossing pulse signal. The controller is connected to the signal modulation circuit, which transmits the zero-crossing pulse signal to the signal modulation circuit. The signal modulation circuit is used to output the H-bridge control signal.

[0010] The H-bridge control circuit, which is connected to the signal modulation circuit, is used to convert the H-bridge control signal into a drive signal and output it to the motor.

[0011] Furthermore, it also includes a PWM generation circuit, which is used to generate a PWM signal with a continuously adjustable duty cycle. The PWM generation circuit is connected to the signal modulation circuit to transmit the PWM signal. The signal modulation circuit converts the zero-crossing pulse signal and the PWM signal into a 50Hz H-bridge control signal with adjustable pulse width.

[0012] Furthermore, the PWM generation circuit includes a potentiometer R12, a transistor Q6, and an operational amplifier comparator U4. The controller is connected to the operational amplifier comparator U4, the operational amplifier comparator U4 is connected to the base of the transistor Q6, the emitter of the transistor Q6 is grounded, and its collector is the output terminal of the PWM generation circuit, which is connected to the signal modulation circuit.

[0013] Furthermore, the H-bridge control circuit includes an H-bridge drive circuit and an H-bridge AC voltage regulator circuit connected to each other. The H-bridge drive circuit amplifies the H-bridge control signal and transmits it to the H-bridge AC voltage regulator circuit. The H-bridge AC voltage regulator circuit outputs the motor drive signal based on the 100Hz DC pulsating signal and the H-bridge control signal.

[0014] Furthermore, the signal modulation circuit includes resistors R3, R4, R6, and R8, and diodes D3 and D4. Different output pins of the controller are connected via resistors R3, R4, R6, and R8, respectively. Resistors R3, R4, R6, and R8 are used to transmit different control signals from the controller to the H-bridge control circuit. The output of the PWM generation circuit branches into two branches. One branch is connected via diode D3 to the connection node between resistor R6 and the H-bridge control circuit, and the other branch is connected via diode D4 to the connection node between resistor R3 and the H-bridge control circuit.

[0015] Further, the H-bridge driving circuit comprises driving chips U2 and U3, the H-bridge AC voltage regulating circuit comprises MOSFET switch tubes Q1-Q4, different output pins of the controller are connected with the driving chips U2 and U3 respectively, two driving signals sent by the driving chip U2 are transmitted to the motor through the MOSFET switch tubes Q1 and Q2 respectively, and two driving signals sent by the driving chip U3 are transmitted to the motor through the MOSFET switch tubes Q3 and Q4 respectively.

[0016] Further, in one of the DC pulse periods, the MOSFET switch tubes Q1 and Q4 are turned on, and the MOSFET switch tubes Q3 and Q2 are turned off; in another of the DC pulse periods, the MOSFET switch tubes Q3 and Q2 are turned on, and the MOSFET switch tubes Q1 and Q4 are turned off.

[0017] Further, in the state that the MOSFET switch tubes Q1 and Q4 are turned on, the MOSFET switch tube Q4 is fully turned on and is used for transmitting the driving signal of the motor, the MOSFET switch tube Q1 is turned on or turned off according to the H-bridge control signal and is used for controlling the amplitude of the positive half-cycle driving signal of the motor, and in the state that the MOSFET switch tubes Q3 and Q2 are turned on, the MOSFET switch tube Q2 is fully turned on and is used for transmitting the driving signal of the motor, and the MOSFET switch tube Q3 is turned on or turned off according to the H-bridge control signal and is used for controlling the amplitude of the negative half-cycle driving signal of the motor.

[0018] Further, the rectifier circuit comprises a first power supply filter circuit, a second power supply filter circuit and a rectifier bridge stack DG connected in sequence, the first power supply filter circuit comprises inductors T1 and a capacitor C7 connected in parallel with each other, and the second power supply filter circuit comprises inductors T2 and a capacitor C8 connected in parallel.

[0019] A range hood using the above-mentioned speed regulating controller, the range hood comprising: a casing, a smoke inlet and a smoke outlet, a cavity arranged in the casing, a fan system and a stepless speed regulating controller arranged in the cavity, the fan in the fan system being electrically connected with the stepless speed regulating controller, and the stepless speed regulating controller being arranged above the fan.

[0020] The beneficial effects of the present application are as follows:

[0021] The application is a stepless speed control device, wherein the zero extraction circuit extracts zero pulse directly from 100Hz pulsating DC current of the commercial rectification circuit, and the zero extraction circuit does not need to set up signal filter capacitor to realize zero pulse, thus, there is no time delay problem of zero pulse extraction, the waveform output by the driving circuit will not be distorted, and the reliability of the system is improved. BRIEF DESCRIPTION OF DRAWINGS

[0022] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The accompanying drawings are included to provide a better understanding of the preferred embodiments, and are not intended to be limiting of the application. Moreover, in the drawings, like reference numerals denote similar or identical components.

[0023] In the drawings:

[0024] Fig. 1 A flowchart illustrating the implementation of the application is shown;

[0025] Fig. 2 A circuit diagram of one part of the application is shown;

[0026] Fig. 3 A circuit diagram of another part of the application is shown.

[0027] Reference numerals:

[0028] 1 - rectification circuit; 2 - zero extraction circuit; 3 - controller; 4 - PWM generation circuit; 5 - signal modulation circuit; 6 - H-bridge driving circuit; 7 - H-bridge AC voltage regulation circuit. DETAILED DESCRIPTION

[0029] In order to make the technical problems solved by the application, technical solutions and beneficial effects more clearly understood, the application will be further described in detail below with reference to the embodiments. However, it should be understood that the specific embodiments described herein are only used to explain the application, and are not used to limit the application.

[0030] See Figs. 1 to 3 The stepless speed control device of the embodiment includes:

[0031] The rectification circuit 1 is used to take power from commercial power and rectify 220V AC voltage input from commercial power into 100Hz DC pulsating signal;

[0032] Zero point extraction circuit 2 is used to collect 100Hz DC pulse signal with rectifier circuit 1, 100Hz DC pulse signal is connected in series through resistance R17, resistance R18, resistance R19 to the b electrode of triode Q5, the e electrode of triode Q5 is connected with resistance R24 to ground, the conduction voltage of triode Q5 is connected to its c electrode through resistance R13, resistance R13 and triode Q5 convert 100Hz DC pulse signal into zero crossing pulse signal, zero point extraction circuit 2 extracts zero crossing pulse signal of 100Hz pulse DC generated by rectifier circuit 1, through resistance R13 and triode Q5 to form level conversion, and generate zero crossing pulse signal compatible with the input / output of controller 3;

[0033] Controller 3 is a single-chip microcomputer with digital-analog conversion function ordinary IO port (such as PIC10F204, SN8P2501B, etc.), which is used to collect zero crossing pulse signal with zero point extraction circuit 2, controller 3 transmits zero crossing pulse signal to signal modulation circuit 5, and signal modulation circuit 5 outputs H bridge control signal;

[0034] H bridge control circuit is connected with signal modulation circuit, and H bridge control circuit is used to convert H bridge control signal into driving signal and output to motor.

[0035] Further, it further includes PWM generation circuit, which is used to generate duty cycle continuously adjustable PWM signal, PWM generation circuit is connected with signal modulation circuit to transmit PWM signal, and signal modulation circuit converts zero crossing pulse signal and PWM signal into 16-18KHz H bridge control signal with adjustable pulse width.

[0036] Further, the PWM generation circuit includes potentiometer R12, triode Q6 and operational amplifier comparator U4, the controller is connected with operational amplifier comparator U4, operational amplifier comparator U4 is connected with the b electrode of triode Q6, the e electrode of triode Q6 is grounded, and the c electrode is the output end of PWM generation circuit and is connected with signal modulation circuit.

[0037] The PWM generating circuit 4 comprises resistor R11, resistor R14, resistor R15, resistor R10, resistor R20, resistor R21, resistor R23, resistor R22, resistor R16, triode Q6, potentiometer R12, operational amplifier comparator U4, and potentiometer R12 for adjusting the pulse high level width of the PWM signal. The PWM generating circuit 4 is used to generate a PWM signal with continuously adjustable duty cycle. The high level width of the PWM pulse is adjusted by changing the potentiometer R12, and then a sine wave voltage (PWM signal) with different amplitudes is obtained. The PWM signal is an equal duty cycle signal. The PWM generating circuit 4 is connected to the signal modulation circuit 5 to transmit the PWM signal. The signal modulation circuit 5 converts the zero-crossing pulse signal and the PWM signal into a 16-18KHz H-bridge control signal with adjustable pulse width, and then realizes the process of chopping and proportional voltage regulation.

[0038] Further, the H-bridge control circuit comprises an H-bridge driving circuit 6 and an H-bridge AC voltage regulation circuit 7. The H-bridge driving circuit 6 is used to amplify the H-bridge control signal and transmit it to the H-bridge AC voltage regulation circuit 7. The H-bridge AC voltage regulation circuit 7 outputs the driving signal of the motor according to the 100Hz DC pulsating signal and the H-bridge control signal.

[0039] Further, the signal modulation circuit 5 comprises resistance R3, resistance R4, resistance R6, resistance R8, diode D3, diode D4, the H-bridge drive circuit 6 comprises drive chip U2, drive chip U3, diode D1, diode D2, capacitor C2, capacitor C3, capacitor C4, capacitor C5, the H-bridge AC voltage regulation circuit 7 comprises MOSFET switch tube Q1 to MOSFET switch tube Q4, resistance R1, resistance R5, resistance R7, resistance R9, the RC0 pin of the controller 3 is connected with the upper arm of the drive chip U2 through resistance R3, the RC1 pin of the controller 3 is connected with the lower arm of the drive chip U2 through resistance R4, the RC2 pin of the controller 3 is connected with the upper arm of the drive chip U3 through resistance R6, the RC3 pin of the controller 3 is connected with the lower arm of the drive chip U3 through resistance R8, the output end of the PWM generation circuit 4 branches into two branches, one of which is connected with the upper arm of the drive chip U3 through diode D3, and the other is connected with the upper arm of the drive chip U2 through diode D4, the high-end output channel of the drive chip U2 drives MOSFET switch tube Q1 through resistance R1, and the low-end output channel thereof drives MOSFET switch tube Q2 through resistance R5, the high-end output channel of the drive chip U3 drives MOSFET switch tube Q3 through resistance R7, and the low-end output channel thereof drives MOSFET switch tube Q4 through resistance R9, and the drive chip U2 and the drive chip U3 are both conventional IR2304, which will not be described here. The PWM generation circuit and the signal modulation circuit 5 connected generate a direct current chopping signal, which is driven by the H-bridge drive circuit to realize chopping voltage regulation of the chopper tubes Q1 and Q3 of the H-bridge AC voltage regulation circuit, so that the chopping frequency of the final drive motor reaches 16-18KHz, and the current waveform tends to be a sine wave.

[0040] Further, in one of the direct current pulse periods, the MOSFET switch tube Q1 and the MOSFET switch tube Q4 are turned on, and the MOSFET switch tube Q3 and the drive MOSFET switch tube Q2 are turned off; in the other direct current pulse period, the MOSFET switch tube Q3 and the MOSFET switch tube Q2 are turned on, and the MOSFET switch tube Q1 and the drive MOSFET switch tube Q4 are turned off.

[0041] Further, in the state that the MOSFET switch tube Q1 and the MOSFET switch tube Q4 are turned on, the MOSFET switch tube Q4 is fully turned on, which is used for transmitting the driving signal of the motor, and the MOSFET switch tube Q1 is turned on or turned off according to the H-bridge control signal, which is used for controlling the amplitude of the positive half cycle driving signal of the motor, the longer the on time, the higher the amplitude of the sine wave voltage output to the motor, and the faster the motor speed; in the state that the MOSFET switch tube Q3 and the MOSFET switch tube Q2 are turned on, the MOSFET switch tube Q2 is fully turned on, which is used for transmitting the driving signal of the motor, and the MOSFET switch tube Q3 is turned on or turned off according to the H-bridge control signal, which is used for controlling the amplitude of the negative half cycle driving signal of the motor, the longer the on time, the higher the amplitude of the sine wave voltage output to the motor, and the faster the motor speed.

[0042] Further, the rectifier circuit 1 comprises a first power supply filter circuit, a second power supply filter circuit and a rectifier bridge stack DG connected in sequence, the first power supply filter circuit comprises an inductor T1 and a capacitor C7 connected in parallel, and the second power supply filter circuit comprises an inductor T2 and a capacitor C8 connected in parallel. The rectifier bridge stack DG converts the input alternating current of the speed controller 3 into 100Hz pulsed direct current, so that the rectifier circuit 1 of the embodiment does not need capacitor filtering, and using no capacitor filtering can not only reduce the production cost of the circuit, but also solve the signal delay problem existing in the capacitor. At the same time, in the case of reducing the pulsed direct current to 50Hz voltage-adjustable alternating current, the power factor will not be reduced because the load current is still a sine wave after voltage regulation.

[0043] A range hood using the above speed controller 3, the range hood comprises a housing, a smoke inlet and a smoke outlet, a cavity arranged in the housing, a fan system and the stepless speed controller 3 arranged in the cavity, the fan in the fan system is electrically connected with the stepless speed controller 3, and the stepless speed controller 3 is arranged above the fan. In the range hood, the above stepless speed controller 3 is arranged, the stepless speed controller 3 is used to realize continuous adjustment of the fan speed, and the stepless speed controller 3 is more suitable for the needs of users. At the same time, the H-bridge structure can solve the current freewheeling problem of the alternating current motor when the PWM pulse is turned off, the current of the alternating current motor is continuous in the mains cycle, and the eddy current loss of the motor is not increased, so that the temperature rise of the motor is reduced, and the efficiency of the whole machine is improved. A man-machine control panel is arranged in the face frame of the housing, and the controlled end of the potentiometer R12 is arranged on the man-machine control panel. In order for the user to input the required pulse width.

[0044] With the increase of the carrier frequency of the speed controller, the experiment shows that when the carrier frequency is increased to 16KHZ or higher, the higher the operating frequency, the greater the duty cycle of the voltage wave, and the smaller the current high harmonic component, that is, the higher the carrier frequency, the better the smoothness of the current waveform. The circuit high harmonic component of the embodiment is very small, at the same time, when the motor operates at a high frequency carrier driving signal, the vibration frequency of the motor is greatly improved, so that the metal ringing when the motor vibrates is significantly reduced to more than the degree of human ear perception, thus "disappearing", and the human ear cannot hear the vibration sound of the motor, thereby realizing low noise transmission. By increasing the carrier frequency, the current waveform of the motor (especially the current of the motor at low speed) tends to be a sine wave, thereby reducing the pulsation and loss of the motor torque.

[0045] The specific working process is as follows:

[0046] The PWM generation circuit 4 generates a pulse width modulation carrier signal, and the zero crossing pulse signal collected by the controller 3 is combined to generate an H bridge control signal. The 7th pin (B2-L) of the controller 3 generates a switching signal that turns on in the positive half cycle of the sine wave and turns off in the negative half cycle, which is used to drive the on and off of the MOS tube Q4; the 10th pin (B1-H) of the controller 3 is synchronized with the 7th pin (B2-L), and after logical "and" with the pulse width modulation carrier signal output by the transistor Q6 of the PWM generation circuit, a pulse width modulation signal in the positive half cycle of the sine wave is generated, which is used to drive the pulse width modulation of the MOS tube Q1.

[0047] The 9th pin (B1-L) of the controller 3 generates a switching signal that turns on in the negative half cycle of the sine wave and turns off in the positive half cycle, which is used to drive the on and off of the MOS tube Q2; the 8th pin (B2-H) of the controller 3 is synchronized with the 9th pin (B1-L), and after logical "and" with the pulse width modulation carrier signal output by the transistor Q6 of the PWM generation circuit, a pulse width modulation signal in the negative half cycle of the sine wave is generated, which is used to drive the pulse width modulation of the MOS tube Q3.

[0048] In the H bridge AC voltage regulation circuit: (1) MOS tube Q4 as the first main switch, responsible for the positive half cycle of the sine wave and the negative half cycle of the sine wave; MOS tube Q1 as the first chopping voltage regulation switch, in the positive half cycle of the sine wave, the voltage amplitude is regulated by the PWM pulse width modulation signal. (2) MOS tube Q2 as the second main switch, responsible for the positive half cycle of the sine wave and the negative half cycle of the sine wave; MOS tube Q3 as the second chopping voltage regulation switch, in the negative half cycle of the sine wave, the voltage amplitude is regulated by the PWM pulse width modulation signal.

[0049] In the entire working cycle of the controller, the two chopping tubes work alternately in the positive and negative half cycles, and the reliability is improved by one time.

[0050] The embodiment has the following beneficial effects:

[0051] The 100Hz pulsating direct current is generated by the rectifier circuit 1, and then the zero-crossing pulse signal is extracted by the zero extraction circuit 2, and no capacitor filtering is required in the zero extraction circuit 2, thereby reducing the complexity of the circuit composition, and avoiding the waveform distortion problem of the H-bridge control circuit output caused by the charge and discharge delay characteristics of the capacitor. In the embodiment, only two of the four MOSFET switch tubes are turned on in the same pulsating period in the H-bridge AC voltage regulating circuit 7, the switch tubes of the same bridge arm are switched at the zero-crossing point of the mains, at this time the bus voltage is close to 0V, the risk of common conduction of the same bridge arm can be reduced, the 100Hz pulsating direct current is reduced to 50Hz voltage adjustable AC power, and the power factor will not be reduced after voltage regulation because the load current is still a sine wave, and the speed control device 3 is ensured to work safely and reliably. In a direct current pulsating period, only two MOSFET tubes are in working state, and the other two are in closed state, and one of the two MOSFET tubes in working state is fully on, and the other one is in pulse switching mode, so that the power consumption of the entire H-bridge can be reduced to about 50%, which is more energy-saving and environmentally friendly.

[0052] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, and are not limited to the scope of the present application. Although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced by equivalents without departing from the essence and scope of the present application.

Claims

1. A stepless speed control device, characterized by comprising: The application relates to a zero-crossing detection and H-bridge control circuit for a motor, which comprises the following parts: a rectifier circuit for taking power from commercial power and rectifying the alternating voltage of the commercial power into a 100Hz direct-current pulsating signal; a zero-point extraction circuit connected with the rectifier circuit to collect the 100Hz direct-current pulsating signal, which sequentially passes through a series connection of a resistor R17, a resistor R18 and a resistor R19 to the b electrode of a triode Q5, the e electrode of the triode Q5 is connected with the b electrode and grounded through a resistor R24, the conduction voltage of the triode Q5 is transmitted to the c electrode through a resistor R13, and the resistor R13 and the triode Q5 convert the 100Hz direct-current pulsating signal into a zero-crossing pulse signal; a controller connected with the zero-point extraction circuit to collect the zero-crossing pulse signal, the controller is connected with a signal modulation circuit, the controller transmits the zero-crossing pulse signal to the signal modulation circuit, and the signal modulation circuit is used for outputting an H-bridge control signal; an H-bridge control circuit connected with the signal modulation circuit, which is used for converting the H-bridge control signal into a driving signal and outputting the driving signal to the motor; a PWM generation circuit for generating a PWM signal with a continuously adjustable duty cycle, the PWM generation circuit is connected with the signal modulation circuit to transmit the PWM signal, and the signal modulation circuit synthesizes the zero-crossing pulse signal and the PWM signal into an H-bridge control signal with a 16-18KHz adjustable pulse width; the H-bridge control circuit comprises an H-bridge driving circuit and an H-bridge alternating voltage regulation circuit connected with each other, the H-bridge driving circuit is used for amplifying the H-bridge control signal and transmitting the H-bridge control signal to the H-bridge alternating voltage regulation circuit, and the H-bridge alternating voltage regulation circuit is used for outputting the driving signal of the motor according to the 100Hz direct-current pulsating signal and the H-bridge control signal; the signal modulation circuit comprises a resistor R3, a resistor R4, a resistor R6, a resistor R8, a diode D3 and a diode D4, different output pins of the controller are connected through the resistor R3, the resistor R4, the resistor R6 and the resistor R8 respectively, the resistor R3, the resistor R4, the resistor R6 and the resistor R8 are respectively used for transmitting on-off switch signals of positive and negative half cycles of a sine wave to the H-bridge control circuit, an output end of the PWM generation circuit is branched into two branches, a pulse width modulation carrier signal output by one branch is connected to a connection node of the resistor R6 and the H-bridge control circuit after logical AND operation with a corresponding control signal, and the pulse width modulation carrier signal is used as a pulse width regulation signal for driving a switch tube in the negative half cycle of the sine wave of the H-bridge alternating voltage regulation circuit, and a pulse width modulation carrier signal output by the other branch is connected to a connection node of the resistor R3 and the H-bridge control circuit after logical AND operation with a corresponding control signal, and the pulse width modulation carrier signal is used as a pulse width regulation signal for driving a switch tube in the positive half cycle of the sine wave of the H-bridge alternating voltage regulation circuit.

2. The infinitely variable speed controller of claim 1, wherein, the PWM generation circuit comprises a potentiometer R12, a triode Q6 and an operational amplifier comparator U4, the controller is connected with the operational amplifier comparator U4, the operational amplifier comparator U4 is connected with the b electrode of the triode Q6, the e electrode of the triode Q6 is grounded, and the c electrode is an output end of the PWM generation circuit and is connected with the signal modulation circuit.

3. The infinitely variable speed controller of claim 1, wherein, The H-bridge driving circuit comprises driving chips U2 and U3, the H-bridge AC voltage regulating circuit comprises MOSFET switch tubes Q1-Q4, different output pins of the controller are connected with the driving chips U2 and U3 respectively, two time-sharing transmitted driving signals of the driving chip U2 are transmitted to the motor through the MOSFET switch tubes Q1 and Q2 respectively, and two time-sharing transmitted driving signals of the driving chip U3 are transmitted to the motor through the MOSFET switch tubes Q3 and Q4 respectively.

4. The infinitely variable speed controller of claim 3, wherein: In one of the direct current pulse periods, the MOSFET switch tubes Q1 and Q4 are turned on, and the MOSFET switch tubes Q3 and Q2 are turned off; in another direct current pulse period, the MOSFET switch tubes Q3 and Q2 are turned on, and the MOSFET switch tubes Q1 and Q4 are turned off.

5. The infinitely variable speed controller of claim 4, wherein: In the state that the MOSFET switch tubes Q1 and Q4 are turned on, the MOSFET switch tube Q4 is fully turned on and is used for transmitting the driving signal of the motor, the MOSFET switch tube Q1 is turned on or turned off according to the H-bridge control signal and is used for controlling the amplitude of the positive half cycle driving signal of the motor, and the MOSFET switch tubes Q3 and Q2 are turned on; in the state that the MOSFET switch tubes Q3 and Q2 are turned on, the MOSFET switch tube Q2 is fully turned on and is used for transmitting the driving signal of the motor, the MOSFET switch tube Q3 is turned on or turned off according to the H-bridge control signal and is used for controlling the amplitude of the negative half cycle driving signal of the motor.

6. The infinitely variable speed controller of claim 1, wherein: The rectifier circuit comprises a first power supply filter circuit, a second power supply filter circuit and a rectifier bridge stack DG connected in sequence, the first power supply filter circuit comprises an inductor T1 and a capacitor C7 connected in parallel with each other, and the second power supply filter circuit comprises an inductor T2 and a capacitor C8 connected in parallel.

7. A range hood using the speed control device according to any one of claims 1 to 6, characterized by The range hood comprises a casing, a smoke inlet and a smoke outlet, a cavity arranged in the casing, a fan system and a stepless speed control controller arranged in the cavity, a fan in the fan system is electrically connected with the stepless speed control controller, and the stepless speed control controller is arranged above the fan.

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