阅读说明：本技术 一种脉宽时长监测电路、加热装置和脉宽时长监测方法 (Pulse width duration monitoring circuit, heating device and pulse width duration monitoring method ) 是由 张明生 梁旭东 于 2020-12-14 设计创作，主要内容包括：本发明提供了一种脉宽时长监测电路、加热装置和脉宽时长监测方法,属于加热设备技术领域。该脉宽时长监测电路包括延时电路,延时电路与加热装置的控制器连接；开关电路,开关电路的第一端与延时电路连接,开关电路的第二端接地；加热电压电路,加热电压电路的第一端与延时电路和开关电路并联连接,加热电压电路的第二端与加热装置的加热电路连接,加热电压电路还连接有一电源电压端。解决了现有技术中当加热装置控制器输出的PWM信号一直处于高电平时,被加热物一直处于加热之中,容易烧坏的技术问题。(The invention provides a pulse width and time duration monitoring circuit, a heating device and a pulse width and time duration monitoring method, and belongs to the technical field of heating equipment. The pulse width and time duration monitoring circuit comprises a delay circuit, wherein the delay circuit is connected with a controller of the heating device; the first end of the switch circuit is connected with the delay circuit, and the second end of the switch circuit is grounded; and the first end of the heating voltage circuit is connected with the delay circuit and the switch circuit in parallel, the second end of the heating voltage circuit is connected with the heating circuit of the heating device, and the heating voltage circuit is also connected with a power supply voltage end. The technical problem that in the prior art, when the PWM signal output by the heating device controller is always at a high level, a heated object is always heated and is easily burnt out is solved.)

1. A pulse width duration monitoring circuit for use in a heating apparatus, the pulse width duration monitoring circuit comprising:

the time delay circuit is connected with a controller of the heating device, the controller is used for outputting PWM control signals, the PWM control signals comprise a high level and a low level, and the time delay circuit is used for monitoring the duration of the high level in the PWM control signals output by the controller;

the switching circuit is connected with the delay circuit and used for stopping when the duration of the high level does not exceed the preset duration of the delay circuit; when the high level duration of the PWM signal exceeds the preset duration of the delay circuit, the switch circuit is switched on;

the heating voltage circuit, the first end of heating voltage circuit with delay circuit with switch circuit parallel connection, the second end of heating voltage circuit with heating device's heating circuit is connected, the heating voltage circuit still is connected with a mains voltage end, works as when switch circuit is the off-state, the heating voltage circuit switches on, works as when switch circuit is the on-state, the heating voltage circuit is the off-state.

2. The pulse width and duration monitoring circuit according to claim 1, wherein the delay circuit comprises an RC series circuit consisting of a resistor R001 and a capacitor C001, wherein the capacitor C001 is a polar capacitor, the resistor R001 is connected in series with one end of the positive pole of the capacitor C001, one end of the RC series circuit where the resistor R001 is located is connected to the controller of the heating device, and one end of the RC series circuit where the capacitor C001 is located is grounded.

3. The pulse width and time duration monitoring circuit according to claim 2, wherein the delay circuit further comprises a discharge circuit consisting of a resistor R002, a capacitor C001 and a diode D001, wherein the resistor R002 is connected in parallel with the capacitor C001, and an anode of the capacitor C001 is connected to an anode of the diode D001.

4. The circuit of claim 1, wherein the switching circuit comprises an NPN transistor Q001 and an NPN transistor Q002, a base of the NPN transistor Q001 is connected to the delay circuit, an emitter of the NPN transistor Q001 is connected to a base of the NPN transistor Q002, a collector of the NPN transistor Q001 is connected to a voltage supply terminal, an emitter of the NPN transistor Q002 is grounded, and a collector of the NPN transistor Q002 is connected to the controller of the heating device.

5. The pulse width and duration monitoring circuit of claim 4, wherein the collector of the NPN transistor Q001 is connected to the supply voltage terminal through a resistor R003, and the collector of the NPN transistor Q002 is connected to the controller of the heating device through a resistor R004.

6. The pulse width and duration monitoring circuit according to claim 1, wherein the heating voltage circuit comprises an NPN transistor Q003 and an NPN transistor Q004, wherein the NPN transistor Q003 is connected to the controller of the heating device, an emitter of the NPN transistor Q002 is grounded, a collector of the NPN transistor Q004 is connected to the power voltage terminal, the NPN transistor Q004 is connected in parallel between the NPN transistor Q003 and the power voltage terminal, wherein a base of the NPN transistor Q004 is connected to the end where the power voltage terminal is located, a collector of the NPN transistor Q004 is connected to the end where the collector of the NPN transistor Q003 is located, and an emitter of the NPN transistor Q004 is connected to the heating circuit of the heating device.

7. The pulse width duration monitoring circuit of claim 6, wherein the NPN transistor Q003 is connected to the power voltage terminal through a resistor R005 and a resistor R006 connected in series, wherein the NPN transistor Q004 is connected in parallel to the resistor R005.

8. The pulse width and duration monitoring circuit of claim 6, wherein a resistor R007 is connected in parallel between the base and the emitter of the NPN transistor Q003.

9. A heating device comprising a pulse width duration monitoring circuit as claimed in any one of claims 1 to 8.

10. A pulse width duration monitoring method applied to the pulse width duration monitoring circuit according to any one of claims 1 to 8, the method comprising:

receiving a PWM signal output from a controller of the heating device through the delay circuit, wherein the PWM signal comprises a high level and a low level;

a time threshold value is preset through the time delay circuit, and whether the high level duration time of the PWM signal exceeds the time threshold value is detected;

when the duration of the high level of the PWM signal does not exceed the preset duration of the delay circuit or the PWM signal is in a low level state, the switching circuit is cut off; when the high level duration of the PWM signal exceeds the preset duration of the delay circuit, the switch circuit is switched on;

and supplying power to the heating circuit of the heating device through the heating voltage circuit, wherein when the heating voltage circuit is in a conducting state in the switch circuit, the heating voltage circuit stops supplying power to the heating circuit of the heating device, and when the heating voltage circuit is in a stopping state in the switch circuit, the heating voltage circuit starts supplying power to the heating circuit of the heating device.

Technical Field

The invention relates to the technical field of heating devices, in particular to a pulse width duration monitoring circuit, a heating device and a pulse width duration monitoring method.

Background

The heating device is a device for converting electric energy into heat energy, and mainly comprises heating modes such as resistance heating, induction heating, arc heating, electron beam heating, infrared heating, medium heating and the like.

In the prior art, the main operating principle of the heating device is the following: the heating device generally comprises a controller and a heating circuit, when a specific heated body needs to be heated, the controller sends a signal to control the heating circuit to heat the heated body, in a nitrogen oxygen sensor and a particulate matter sensor used in an automobile, the ceramic chip in the nitrogen oxygen sensor and the particulate matter sensor needs to be heated to a high temperature (above 800 ℃), and the heating of the ceramic chip is mainly realized by adopting the controller to output a PWM signal to control the power output by the heating circuit, when the controller outputs the PWM signal due to some special reasons and is out of control, if the program of the controller is in a dead cycle (or the logic circuit is interfered), the output PWM signal is always in a high level, the ceramic chip is always in heating, and the ceramic chip is overheated, the chip is burnt out, so that the whole sensor is damaged, a fault is caused to a running vehicle, and the potential safety hazard is very large.

The applicant of the present invention finds that the prior art has at least the following technical problems:

in the prior art, when the controller outputs the PWM signal out of control due to some special reasons, for example, the PWM signal out of control for a long time when a program of the controller has a dead cycle (or a logic circuit is interfered), so that the output PWM signal is always at a high level, the ceramic chip is always heated, and at this time, overheating of the ceramic chip is caused, the chip is burnt out, and therefore the whole sensor is damaged, a fault is caused to a running vehicle, and the potential safety hazard is very large.

Disclosure of Invention

The embodiment of the invention provides a pulse width duration monitoring circuit, a heating device and a pulse width duration monitoring method, and solves the technical problems that in the prior art, when a controller outputs a PWM signal out of control due to some special reasons, if a program of the controller is in a dead cycle (or a logic circuit is interfered), the output PWM signal is always in a high level, a ceramic chip is always in heating, the ceramic chip is overheated at the moment, the chip is burnt out, the whole sensor is damaged, a fault is caused to a running vehicle, and the potential safety hazard is very large.

In view of the foregoing problem, in a first aspect, an embodiment of the present invention provides a pulse width duration monitoring circuit for use in a heating device, the pulse width duration monitoring circuit including: the time delay circuit is connected with a controller of the heating device, the controller is used for outputting PWM control signals, the PWM control signals comprise a high level and a low level, and the time delay circuit is used for monitoring the duration of the high level in the PWM control signals output by the controller; the switching circuit is connected with the delay circuit and used for stopping when the duration of the high level does not exceed the preset duration of the delay circuit; when the high level duration of the PWM signal exceeds the preset duration of the delay circuit, the switch circuit is switched on; the heating voltage circuit, the first end of heating voltage circuit with delay circuit with switch circuit parallel connection, the second end of heating voltage circuit with heating device's heating circuit is connected, the heating voltage circuit still is connected with a mains voltage end, works as when switch circuit is the off-state, the heating voltage circuit switches on, works as when switch circuit is the on-state, the heating voltage circuit is the off-state.

Preferably, the delay circuit includes an RC series circuit composed of a resistor R001 and a capacitor C001, where the capacitor C001 is a polar capacitor, the resistor R001 is connected in series with one end of the positive electrode of the capacitor C001, one end of the RC series circuit where the resistor R001 is located is connected to the controller of the heating device, and one end of the RC series circuit where the capacitor C001 is located is grounded.

Preferably, the delay circuit further includes a discharge circuit composed of a resistor R002, a capacitor C001, and a diode D001, wherein the resistor R002 is connected in parallel with the capacitor C001, and an anode of the capacitor C001 is connected to an anode of the diode D001.

Preferably, the switching circuit includes an NPN triode Q001 and an NPN triode Q002, a base of the NPN triode Q001 is connected to the delay circuit, an emitter of the NPN triode Q001 is connected to a base of the NPN triode Q002, a collector of the NPN triode Q001 is connected to a power supply voltage terminal, an emitter of the NPN triode Q002 is grounded, and a collector of the NPN triode Q002 is connected to the controller of the heating device.

Preferably, a collector of the NPN transistor Q001 is connected to the power supply voltage terminal through a resistor R003, and a collector of the NPN transistor Q002 is connected to the controller of the heating device through a resistor R004.

Preferably, the heating voltage circuit includes an NPN triode Q003 and an NPN triode Q004, wherein the NPN triode Q003 is connected to the controller of the heating device, an emitter of the NPN triode Q002 is grounded, a collector of the NPN triode Q004 is connected to the power supply voltage terminal, the NPN triode Q004 is connected in parallel between the NPN triode Q003 and the power supply voltage terminal, a base of the NPN triode Q004 is connected to the terminal where the power supply voltage terminal is located, a collector of the NPN triode Q004 is connected to the terminal where the collector of the NPN triode Q003 is located, and the emitter of the NPN triode Q004 is connected to the heating circuit of the heating device.

Preferably, the NPN transistor Q003 is connected to the power voltage terminal through a resistor R005 and a resistor R006 connected in series, wherein the NPN transistor Q004 is connected in parallel to the resistor R005.

Preferably, a resistor R007 is connected in parallel between the base and the emitter of the NPN triode Q003.

In a second aspect, embodiments of the present invention provide a heating apparatus comprising a pulse width duration monitoring circuit as claimed in any one of claims 1 to 8.

In a third aspect, an embodiment of the present invention provides a pulse width duration monitoring method, which is applied to a pulse width duration monitoring circuit according to any one of the preceding claims, and the method includes:

receiving a PWM signal output from a controller of the heating device through the delay circuit, wherein the PWM signal comprises a high level and a low level; a time threshold value is preset through the time delay circuit, and whether the high level duration time of the PWM signal exceeds the time threshold value is detected; when the duration of the high level of the PWM signal does not exceed the preset duration of the delay circuit or the PWM signal is in a low level state, the switching circuit is cut off; when the high level duration of the PWM signal exceeds the preset duration of the delay circuit, the switch circuit is switched on; and supplying power to the heating circuit of the heating device through the heating voltage circuit, wherein when the heating voltage circuit is in a conducting state in the switch circuit, the heating voltage circuit stops supplying power to the heating circuit of the heating device, and when the heating voltage circuit is in a stopping state in the switch circuit, the heating voltage circuit starts supplying power to the heating circuit of the heating device.

One or more technical solutions in the embodiments of the present application have at least one or more of the following technical effects:

the embodiment of the invention provides a pulse width and duration monitoring circuit, which is used in a heating device and comprises: when the heating device is used, the delay circuit is connected with a controller of the heating device, the heating voltage circuit is connected with the heating circuit of the heating device, when the duration time of the high level of a PWM signal output by the controller of the heating device exceeds the preset duration time of the delay circuit, the switching circuit is switched on, so that the heating voltage circuit is switched off to stop supplying power to the heating circuit, when the PWM signal is normal, namely the duration time of the high level of the PWM signal is less than the preset duration time of the delay circuit or the PWN signal is low level, the switching circuit is switched off, so that the heating voltage circuit is switched on and starts supplying power to the heating circuit, when the duration time of the high level of the PWM signal exceeds the preset duration time of the delay circuit, the heating voltage of the heating circuit is automatically switched off, so that the ceramic chip is protected from being burnt, and when the PWM signal is recovered to be normal, the switching circuit releases the output of the PWM signal, the ceramic chip can be normally powered and heated, and the PWM signal is normally protected and recovered after being out of control for a short time, so that the technical problems that in the prior art, when the PWM signal is out of control due to certain special reasons when the controller outputs the PWM signal, if the PWM signal is out of control for a long time when a program of the controller is in a dead cycle (or a logic circuit is interfered), the output PWM signal is always at a high level, the ceramic chip can be always in heating, overheating of the ceramic chip can be caused at the moment, the chip is burnt out, the whole sensor is damaged, faults are caused to a running vehicle, and potential safety hazards are very large are solved.

The foregoing description is only an overview of the technical solutions of the present invention, and the embodiments of the present invention are described below in order to make the technical means of the present invention more clearly understood and to make the above and other objects, features, and advantages of the present invention more clearly understandable.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.

FIG. 1 is a block diagram of a pulse width and duration monitoring circuit according to an embodiment of the present invention;

FIG. 2 is a schematic circuit diagram of a pulse width and duration monitoring circuit according to an embodiment of the present invention;

fig. 3 is a flowchart of a pulse width duration monitoring method according to an embodiment of the present invention.

Description of reference numerals: 110. a delay circuit; 120. a switching circuit; 130. a heating voltage circuit; 200. a heating device; 210. a controller; 220. a heating circuit.

Detailed Description

The embodiment of the invention provides a pulse width duration monitoring circuit, a heating device and a pulse width duration monitoring method, which are used for solving the technical problems that in the prior art, when a controller outputs a PWM signal out of control due to some special reasons, if a program of the controller is in a dead cycle (or a logic circuit is interfered), the output PWM signal is always in a high level, a ceramic chip is always in heating, the ceramic chip is overheated at the moment, the chip is burnt out, the whole sensor is damaged, a fault is caused to a running vehicle, and potential safety hazards are very large.

The technical scheme provided by the invention has the following general idea:

the pulse width and time duration monitoring circuit comprises a delay circuit, the delay circuit is connected with a controller of the heating device, the controller is used for outputting PWM control signals, the PWM control signals comprise a high level and a low level, and the delay circuit is used for monitoring the duration of the high level in the PWM control signals output by the controller; the switching circuit is connected with the delay circuit and used for stopping when the duration of the high level does not exceed the preset duration of the delay circuit; when the high level duration of the PWM signal exceeds the preset duration of the delay circuit, the switch circuit is switched on; the heating voltage circuit, the first end of heating voltage circuit with delay circuit with switch circuit parallel connection, the second end of heating voltage circuit with heating device's heating circuit is connected, the heating voltage circuit still is connected with a mains voltage end, works as when switch circuit is the off-state, the heating voltage circuit switches on, works as when switch circuit is the on-state, the heating voltage circuit is the off-state. When the duration of the high level of the PWM signal exceeds the duration preset by the delay circuit, the heating voltage of the heating circuit is automatically cut off, so that the ceramic chip is protected from being burnt, when the PWM signal is recovered to be normal, the switching circuit releases the output of the PWM signal, the ceramic chip can be normally powered and heated, and when the PWM signal is out of control for a short time, the problem of normal protection and recovery is solved, so that the problem that when the PWM signal is out of control due to some special reasons in the prior art, for example, when the program of the controller is out of control for a long time when the program of the controller has dead cycle (or logic circuit is interfered), the output PWM signal is always in the high level, the ceramic chip is always in heating, overheating of the ceramic chip can be caused at the moment, the chip is burnt out, and the whole sensor is damaged is solved, the technical problems of faults and great potential safety hazards are caused to the running vehicles.

It should be understood that, in the embodiment of the present invention, the PWM control signal (Pulse width modulation) generally refers to Pulse width modulation, and Pulse width modulation is an analog control manner, and modulates the bias of the base of the transistor or the gate of the MOS transistor according to the change of the corresponding load to change the conduction time of the transistor or the MOS transistor, so as to change the output of the switching regulator, so that the output voltage of the power supply can be kept constant when the operating condition changes, which is a very effective technique for controlling an analog circuit by using the digital signal of the microprocessor. Pulse width modulation is a very efficient technique for controlling analog circuits using the digital output of a microprocessor, and is widely used in many fields ranging from measurement, communications to power control and conversion.

It should be understood that, in the embodiment of the present invention, the NPN transistor refers to a transistor formed by sandwiching a P-type semiconductor between two N-type semiconductors, which is also called a transistor, and the transistor is the most important device in an electronic circuit, and its main functions are current amplification and switching, and it can convert a weak electrical signal into a signal with a certain intensity, although the conversion still follows energy conservation, it only converts the energy of a power supply into the energy of the signal, the transistor has three electrodes as its name implies, the diode is formed by a PN junction, the transistor is formed by two PN junctions, one electrode in common is the Base electrode (denoted by the letter B-B from Base, basic, or Base), and the other two electrodes are respectively called a Collector electrode (denoted by the letter C-C from Collector, and a Collector electrode (denoted by the letter E-E from Emitter, emitter), the junction between the base region and the emitter region becomes an emitter junction, and the junction between the base region and the collector region becomes a collector junction.

It should be understood that, in the embodiment of the present invention, the controller is a microcomputer system, such as a single chip microcomputer, which mainly adopts the very large scale integrated circuit technology to integrate the functions of a central processing unit CPU with data processing capability, a random access memory RAM, a read only memory ROM, various I/O ports and interrupt systems, a timer/counter (which may further include circuits such as a display driving circuit, a pulse width modulation circuit, an analog multiplexer, an a/D converter, etc.) onto a silicon chip to form a small and perfect microcomputer system, which is widely applied in the field of industrial control.

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example one

Fig. 1 is a schematic block diagram of a pulse width duration monitoring circuit according to an embodiment of the present invention, and referring to fig. 1, the pulse width duration monitoring circuit according to an embodiment of the present invention is used in a heating apparatus 200, and the pulse width duration monitoring circuit includes: delay circuit 110, switching circuit 120, heating voltage circuit 130.

The delay circuit 110 is connected to a controller 210 of the heating apparatus 200, wherein the controller 210 is configured to output a PWM control signal, the PWM control signal comprises a high level and a low level, the delay circuit 110 is configured to monitor a duration of the high level in the PWM control signal output by the controller 210, the delay circuit 110 is a circuit that is used to delay one signal for a certain time and then react with another signal in digital circuit design, which mainly comprises a precise long delay circuit, an rc delay circuit, a 555 long delay circuit, a monostable delay circuit, a transistor delay circuit and the like, wherein the precise long-delay circuit is mainly a time-base circuit of a timer consisting of CD4060, a timing time-base pulse generated by the circuit, outputting a time base signal after frequency division is carried out by an internal frequency divider, and then carrying out frequency division by an external frequency dividing circuit to obtain the required timing control time; the RC circuit generally uses a resistor and a capacitor connected in series, and the capacitor is charged through the resistor to achieve the effect of time delay.

Further, referring to fig. 2, the delay circuit 110 includes an RC series circuit composed of a resistor R001 and a capacitor C001, where the capacitor C001 is a polar capacitor, the resistor R001 is connected in series with an anode end of the capacitor C001, an end of the RC series circuit where the resistor R001 is located is connected to the controller of the heating device, an end of the RC series circuit where the capacitor C001 is located is grounded, and by using the RC series circuit composed of the resistor R001 and the capacitor C001, the delay time duration can be adjusted by changing parameter values of the resistor R001 and the capacitor C001, so that the delay circuit is suitable for protection of all PWM control signals in a heating manner, and meanwhile, by using the RC delay circuit, the delay circuit has advantages of real-time, rapidness, effectiveness, and low cost.

Further, the delay circuit 110 further includes a discharge circuit composed of a resistor R002, a capacitor C001, and a diode D001, wherein the resistor R002 is connected in parallel with the capacitor C001, an anode of the capacitor C001 is connected to an anode of the diode D001, the diode D001 is used to enable the capacitor C001 to discharge rapidly, when the PWM signal is at a low level, a charging voltage on the capacitor C001 is Vpr1, the discharge is performed through the discharge circuit, and Vpr1 is close to a ground level.

The switch circuit 120 is connected to the delay circuit 110, and the switch circuit 120 is configured to turn off the switch circuit 120 when the duration of the high level does not exceed the preset duration of the delay circuit 110; when the high level duration of the PWM signal exceeds the preset duration of the delay circuit 110, the switch circuit 120 is turned on, wherein the switch circuit 120 may adopt a digital switch circuit and an analog switch circuit, the digital switch circuit mainly comprises a transistor or a MOS transistor, and the switch circuit is widely applied to application occasions such as a switching power supply, a motor drive, an LED drive, a relay drive, and the like; analog switch circuit: because the anti-interference capability of analog signals is not as good as that of digital signals, such as the base current of a transistor can generate a large interference effect on the analog signals, a MOS (metal oxide semiconductor) tube is often used instead of the transistor, and the analog switch circuit is widely applied to the switch application occasions of analog signals such as a high-frequency antenna switch, a sensor analog switch, an audio-video analog switch and the like.

Further, referring to fig. 2, the switch circuit 120 includes an NPN transistor Q001 and an NPN transistor Q002, a base of the NPN transistor Q001 is connected to the delay circuit, an emitter of the NPN transistor Q001 is connected to a base of the NPN transistor Q002, a collector of the NPN transistor Q001 is connected to a power supply voltage terminal, an emitter of the NPN transistor Q002 is grounded, a collector of the NPN transistor Q002 is connected to the controller of the heating apparatus, a collector of the NPN transistor Q001 is connected to the power supply voltage terminal through a resistor R003, a collector of the NPN transistor Q002 is connected to the controller of the heating apparatus through a resistor R004, wherein when the PWM signal is at a high level, a voltage at an IO1 terminal charges a capacitor C001 through the resistor R001, a voltage at Vpr1 in fig. 2 gradually rises, and when a Vpr1 voltage is lower than a turn-on voltage of the transistors Q001 and Q002, triode Q001 and triode Q002 are both off, and when the Vpr1 voltage is higher than the turn-on voltage of triode Q001 and triode Q002, triode Q001 and triode Q002 are both on.

A heating voltage circuit 130, a first end of the heating voltage circuit 130 is connected in parallel with the delay circuit 110 and the switch circuit 120, a second end of the heating voltage circuit 130 is connected with the heating circuit of the heating device, the heating voltage circuit 130 is further connected with a power voltage end, when the switch circuit 120 is in a cut-off state, the heating voltage circuit 130 is turned on, when the switch circuit 120 is in a turned-on state, the heating voltage circuit 130 is in a cut-off state, wherein the switch circuit 120 controls a power supply state of the heating voltage circuit 130, and further controls a state of the heating circuit 220 of the controller 200.

Further, referring to fig. 2, the heating voltage circuit 130 includes an NPN transistor Q003 and an NPN transistor Q004, wherein the NPN transistor Q003 is connected to the controller of the heating device, an emitter of the NPN transistor Q002 is grounded, a collector of the NPN transistor Q004 is connected to the power voltage terminal, the NPN transistor Q004 is connected in parallel between the NPN transistor Q003 and the power voltage terminal, a base of the NPN transistor Q004 is connected to the end where the power voltage terminal is located, a collector of the NPN transistor Q004 is connected to the end where the collector of the NPN transistor Q003 is located, the emitter of the NPN transistor Q004 is connected to the heating circuit of the heating device, the NPN transistor Q003 is connected to the power voltage terminal through a resistor R005 and a resistor R006 in series, the NPN transistor Q004 is connected in parallel to the resistor R005, and a resistor R007 is connected in parallel between the base of the NPN transistor Q003 and the emitter, an IO1 port receives input of a PWM signal from the controller 210, an IO2 port is an output port for supplying power to the heating circuit, and Vbat is a power supply of the heating voltage circuit 130, when the PWM signal is at a high level, voltage at an IO1 end charges a capacitor C001 through a resistor R001, voltage at a Vpr1 gradually rises, when the voltage of Vpr1 is lower than the conduction voltage of a triode Q001 and a triode Q002, the triode Q001 and the triode Q002 are both turned off, the voltage of Vpr2 is higher than the conduction voltage of a triode Q003, the triode Q003 is conducted, the triode Q004 is conducted, and the triode Q004 is conducted, so that the Vbat supplies power to the IO2 through the triode Q004, and the heating circuit 220 heats the heated object;

when the Vpr1 voltage is higher than the on-state voltage of the triode Q001 and the triode Q002, the triode Q001 and the triode Q002 are both turned on, the triode Q002 pulls the voltage of the Vpr2 to the ground level, then the triode Q003 is cut off, the triode Q004 is cut off, the Vbat stops supplying power to the IO2 through the triode Q004, and the heating circuit 220 stops heating the heated object.

Example two

A heating apparatus 200 according to an embodiment of the present invention includes a controller 210, a heating circuit 220, and a pulse width duration monitoring circuit in the first embodiment, and various variations and embodiments in the first embodiment are also applicable to the heating apparatus according to the present embodiment, and a method for implementing the heating apparatus in the present embodiment is clear to those skilled in the art from the foregoing detailed description of the pulse width duration monitoring circuit, and therefore, for the sake of brevity of the description, detailed description is not provided herein.

EXAMPLE III

Fig. 3 is a flowchart of a pulse width duration monitoring method according to an embodiment of the present invention, where the method includes:

step S110, receiving a PWM signal output from the controller 210 of the heating apparatus 200 through the delay circuit 110, wherein the PWM signal includes a high level and a low level;

step S120, presetting a time threshold by the delay circuit 110, and detecting whether the high level duration of the PWM signal exceeds the time threshold;

step S130, the switching circuit 120 is turned off when the duration of the high level of the PWM signal does not exceed the preset duration of the delay circuit 110 or the PWM signal is in the low level state through the switching circuit 120; when the high level duration of the PWM signal exceeds the preset duration of the delay circuit 110, the switch circuit 120 is turned on;

step S140, supplying power to the heating circuit 220 of the heating device 200 through the heating voltage circuit 130, wherein when the heating voltage circuit 130 is in an on state at the switch circuit 120, the heating voltage circuit 130 stops supplying power to the heating circuit 220 of the heating device 200, and when the heating voltage circuit 130 is in an off state at the switch circuit 120, the heating voltage circuit 130 starts supplying power to the heating circuit 220 of the heating device 200.

Specifically, in actual use, when the duration of the high level of the PWM signal output by the controller 210 does not exceed the preset duration of the delay circuit 110 or the PWM signal is in the low level state, the switch circuit 120 is turned off, the heating voltage circuit 130 starts to supply power to the heating circuit 220 of the heating apparatus 200, when the duration of the high level of the PWM signal exceeds the preset duration of the delay circuit 110, the switch circuit 120 is turned on, the heating voltage circuit 130 enters the off state through the turn-on of the switch circuit 120, so as to stop supplying power to the heating circuit 220 of the heating apparatus 200, that is, when the duration of the high level of the PWM signal exceeds the duration set by the parameter, the heating voltage on the ceramic chip is automatically cut off, so as to protect the ceramic chip from being burned out, when the PWM signal output by the controller 210 is normal, that is, when the duration of the high level is less than the preset time threshold or the low level is output, the switch circuit 120 is in an off state, and when the heating voltage circuit 130 is in the off state, the heating voltage circuit 130 starts to supply power to the heating circuit 130 of the heating device.

In summary, one or more of the above technical solutions in the embodiments of the present application have at least one or more of the following technical effects:

in the embodiment of the present invention, the pulse width duration monitoring circuit, the heating apparatus and the pulse width duration monitoring method are provided, the pulse width duration monitoring circuit includes a delay circuit 110, a switch circuit 120 and a heating voltage circuit 130, when in use, the delay circuit 110 is connected to the controller 210 of the heating apparatus 200, the heating voltage circuit 130 is connected to the heating circuit 220 of the heating apparatus 200, when the duration of the high level of the PWM signal output by the controller 210 of the heating apparatus 200 exceeds the predetermined duration of the delay circuit, the switch circuit 120 is turned on, so as to turn off the heating voltage circuit 130 and stop supplying power to the heating circuit 220, when the PWM signal is normal, i.e. the duration of the high level of the PWM signal is less than the duration preset by the delay circuit 110 or the PWN signal is at the low level, the switch circuit 120 is turned off, so as to turn on the heating voltage circuit 130 and start supplying power to the heating circuit 220, when the duration of the high level of the PWM signal exceeds the predetermined duration, the heating voltage of the heating circuit 220 is automatically cut off, so as to protect the ceramic chip from being burnt, when the PWM signal is recovered to normal, the switching circuit 120 releases the output of the PWM signal, and can normally supply power and heat the ceramic chip, and when the PWM signal is out of control for a short time, the problem of normal protection and recovery is solved, so that the problem in the prior art that when the PWM signal is out of control due to some special reasons when the controller 210 outputs the PWM signal, for example, when the program of the controller 210 is out of control for a long time and the PWM signal is in high level all the time when the program of the controller 210 is in a dead cycle (or the logic circuit is interfered), the ceramic chip is always in heating, and overheating of the ceramic chip is caused at this time, so as to burn out the chip, and damage to the entire sensor is caused, the technical problems of faults and great potential safety hazards are caused to the running vehicles.

While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. Therefore, it is intended that the appended claims be interpreted as including preferred embodiments and all such alterations and modifications as fall within the scope of the invention.

It will be apparent to those skilled in the art that various modifications and variations can be made in the embodiments of the present invention without departing from the spirit or scope of the embodiments of the invention. Thus, if such modifications and variations of the embodiments of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to encompass such modifications and variations.