CN111668803A - Three-level safety protection circuit of heating system - Google Patents
Three-level safety protection circuit of heating system Download PDFInfo
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- CN111668803A CN111668803A CN202010505913.4A CN202010505913A CN111668803A CN 111668803 A CN111668803 A CN 111668803A CN 202010505913 A CN202010505913 A CN 202010505913A CN 111668803 A CN111668803 A CN 111668803A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
Abstract
The invention discloses a three-level safety protection circuit of a heating system, wherein the heating system comprises an alternating current power supply, a bidirectional thyristor and a heating component. According to the invention, when the work of the component in the heating system is abnormal, such as the short circuit of the bidirectional thyristor, the abnormality is obtained through the current monitoring circuit, and the alternating current power supply is cut off, so that the potential safety hazard caused by continuous heating after the abnormality is prevented; and the silicon controlled rectifier can be turned off and the alternating current power supply can be cut off when the single chip microcomputer is abnormal, for example, the single chip microcomputer fails or is halted, so that the heating system is prevented from being in a continuous heating state. The protection mechanism of the application is comprehensive and effective, and the working safety and reliability of the heating system can be obviously improved.
Description
Technical Field
The application belongs to the technical field of heating system safety protection, and particularly relates to a three-level safety protection circuit of a heating system.
Background
The heating system usually uses a triac controlled heating component, and when the heating system is used, the ambient environment is usually in a high temperature and high humidity state, for example, the ambient temperature is usually 70 degrees celsius or above.
Due to the characteristics of the bidirectional triode thyristor, the bidirectional triode thyristor is easy to have a short circuit problem at high temperature. If the bidirectional controllable silicon is in short circuit, a control circuit of the heating system does not work, the heating component continuously supplies power, the whole system is in a continuous heating state, and a fire disaster is likely to happen; meanwhile, in a high-temperature and high-humidity environment, the single chip microcomputer is prone to failure or crash, the bidirectional controllable silicon can be in a state of being conducted all the time, the whole system can be in a state of continuous heating, a fire disaster is likely to occur, and loss of life and property can be caused. These seriously affect the reliability and safety of the heating system.
Disclosure of Invention
The application aims to provide a three-level safety protection circuit of a heating system, which is used for remarkably improving the safety and the reliability of the heating system.
In order to achieve the purpose, the technical scheme adopted by the application is as follows:
the utility model provides a heating system's tertiary safety protection circuit, heating system includes alternating current power supply, bidirectional thyristor and heating part, heating system's tertiary safety protection circuit includes singlechip, total control switch circuit, current monitoring circuit and heating control circuit, wherein:
the master control switch circuit is used for automatically responding to the normal output voltage and the abnormal output voltage of the single chip microcomputer, switching on or off the alternating current power supply of the heating system according to the normal output voltage and switching off the alternating current power supply of the heating system according to the abnormal output voltage;
the heating control circuit is connected with the bidirectional controllable silicon and used for controlling the work of a heating component, the heating control circuit monitors the normal output voltage and the abnormal output voltage of the singlechip, the bidirectional controllable silicon is switched on according to the normal output voltage, and the bidirectional controllable silicon is switched off according to the abnormal output voltage;
the current monitoring circuit is used for detecting abnormal current generated on the heating system and feeding the abnormal current back to the single chip microcomputer, and the single chip microcomputer controls the alternating current power supply of the heating system to be disconnected through the master control switch circuit after receiving the abnormal current.
Preferably, the master control switch circuit comprises a first anti-lock circuit and a relay K1, the first anti-lock circuit is connected between the single chip microcomputer and a coil of the relay K1, and double normally open contacts of the relay K1 are connected in series to a live wire of an alternating current power supply through connecting terminals ACL1 and ACL 2;
the first anti-locking circuit receives the square waves normally output by the single chip microcomputer and then controls the double normally open contacts of the relay K1 to be closed, so that an alternating current power supply of the heating system is conducted;
or the first anti-locking circuit receives the low level normally output by the singlechip and then controls the double normally open contacts of the relay K1 to be opened, so that the alternating current power supply of the heating system is disconnected;
or the first anti-locking circuit receives the continuous high level or low level output by the singlechip abnormally and then controls the double normally open contacts of the relay K1 to be opened, so that the alternating current power supply of the heating system is disconnected.
Preferably, the first anti-lock circuit comprises a resistor R3, a capacitor C1, a diode D1, a capacitor C2, a resistor R4, a resistor R5 and an NPN triode Q2;
one end of the resistor R3 is connected with the single chip microcomputer, the other end of the resistor R3 is connected with the capacitor C1, the other end of the capacitor C1 is connected with the anode of the diode D1, the cathode of the diode D1 is connected with the resistor R4, the other end of the resistor R4 is connected with the base of the NPN triode Q2, one end of the capacitor C2 is connected with the cathode of the diode D1, the other end of the capacitor C2 is grounded, one end of the resistor R5 is connected with the base of the NPN triode Q2, the other end of the resistor R5 is grounded, the emitter of the NPN triode Q2 is grounded, and the collector of the triode NPN Q2 is connected with.
Preferably, the master control switch circuit further comprises a resistor R2, a resistor R1, a PNP triode Q1 and a diode D2 which are connected between the first anti-lock circuit and the relay K1;
one end of the resistor R2 is connected with the collector of the NPN triode Q2, the other end of the resistor R2 is connected with the base of the PNP triode Q1, the resistor R1 is connected between the base and the emitter of the PNP triode Q1, the emitter of the PNP triode Q1 is connected with the power supply voltage VCC1, the collector of the PNP triode Q1 is connected with the cathode of the diode D2, the anode of the diode D2 is grounded, and the coil of the relay K1 is connected with the diode D2 in parallel.
Preferably, the heating control circuit comprises a second anti-locking circuit connected with the bidirectional thyristor;
the second anti-locking circuit receives the square wave normally output by the singlechip and then controls the conduction of the bidirectional thyristor, and the heating part starts to heat;
or the second anti-locking circuit receives the continuous high level or low level output by the singlechip abnormally and then controls the bidirectional thyristor to be switched off, and the heating component stops heating.
Preferably, the second anti-lock circuit comprises a resistor R23, a resistor R17, a capacitor C6, a diode D4, a diode D6, a capacitor C5, a resistor R18, a resistor R15, and a PNP triode Q3;
one end of the resistor R17 and one end of the resistor R23 are connected and then are connected to the singlechip together, the other end of the resistor R23 is grounded, the other end of the resistor R17 is connected with the capacitor C6, the other end of the capacitor C6 is connected with the cathode of a diode D4, the anode of the diode D4 is connected with a resistor R18, the other end of the resistor R18 is connected with the base of a PNP triode Q3, the anode of the diode D6 is connected with the cathode of the diode D4, the cathode of the diode D6 is connected with a supply voltage VCC2, one end of the capacitor C5 is connected with the anode of the diode D4, the other end of the capacitor C5 is connected with a supply voltage VCC2, one end of the resistor R15 is connected with the base electrode of the PNP triode Q3, the other end of the resistor R15 is connected with the power supply voltage VCC2, the emitting electrode of PNP triode Q3 is connected with supply voltage VCC2, the collecting electrode of PNP triode Q3 is used for connecting the bidirectional triode thyristor.
Preferably, the heating control circuit further comprises an opto-thyristor U2, a resistor R22, a resistor R19, a resistor R20, a resistor R16, a transient suppression diode D5, a capacitor C7 and a resistor R1;
the anode of the control end of the optocoupler silicon controlled rectifier U2 is connected with the collector of a PNP triode Q3, the cathode of the control end of the optocoupler silicon controlled rectifier U2 is grounded through a resistor R22, the T2 pole of the optocoupler silicon controlled rectifier U2 is connected with the control pole G of the bidirectional silicon controlled rectifier through a resistor R19, the resistor R16 is connected between the control pole G of the bidirectional silicon controlled rectifier and the T1 pole of the bidirectional silicon controlled rectifier, the T1 pole of the bidirectional silicon controlled rectifier is connected to a connecting terminal ACL3, the T2 pole of the bidirectional silicon controlled rectifier is connected with the live wire connecting terminal of the heating component, two ends of the transient suppression diode D5 are respectively connected with the T1 pole and the T2 pole of the bidirectional silicon controlled rectifier, one end of the capacitor C7 is connected to a connecting terminal ACL3, the other end of the capacitor C7 is connected with a resistor R21, the other end of the resistor R21 is connected with the live wire connecting terminal of the heating component, and a zero line connecting terminal of the heating part is connected with a zero line of an alternating current power supply.
Preferably, the current monitoring circuit comprises a capacitor C4, a resistor R11, a resistor R8, a resistor R9, a resistor R12, a capacitor C3, an operational amplifier U1, a resistor R14, a diode D3, a resistor R6, a resistor R7, a resistor R13, a resistor R10 and a current transformer L1;
one end of the resistor R8 is connected with the singlechip, the other end of the resistor R8 is connected with the resistor R9, the other end of the resistor R9 is connected with an OUTB pin of the operational amplifier U1, a common end of the capacitor C4 and the resistor R11 after being connected in parallel is connected with one end of the resistor R8 connected with the singlechip, the other common end of the resistor R8 is grounded, the resistor R12 and the capacitor C3 after being connected in series are connected in parallel with the resistor R9, one end of the resistor R12 connected with the capacitor C3 is connected with an INB-pin of the operational amplifier U1, one end of the resistor R14 is connected with an INB + pin of the operational amplifier, the other end of the resistor R14 is connected with a-pin of the diode D3, an anode of the diode D3 is connected with the OUTA pin of the operational amplifier U1, one end of the resistor R6 is connected with the OUTA pin of the operational amplifier U1, the other end of the resistor R6 is respectively connected with an A, one end of the resistor R13 is connected with an INA + pin of the operational amplifier U1, one end of two ends of a secondary side of the current transformer L1 is connected with the other end of the resistor R13, the other end of the two ends of the secondary side of the current transformer L49368 is grounded, the resistor R10 is connected with the secondary side of the current transformer L1 in parallel, a VDD pin of the operational amplifier U1 is connected with a power supply voltage VCC2, a VSS pin of the operational amplifier U1 is grounded, and two ends of a primary side of the current transformer L1 are respectively connected with a connecting terminal ACL 2.
According to the three-level safety protection circuit of the heating system, when the work of the components in the heating system is abnormal (such as the short circuit of the bidirectional thyristor), the current monitoring circuit obtains the abnormality and cuts off the alternating current power supply, so that potential safety hazards caused by continuous heating after the abnormality are prevented; and the silicon controlled rectifier can be turned off and the alternating current power supply can be cut off when the single chip microcomputer is abnormal (for example, the single chip microcomputer fails or is halted), so that the heating system is prevented from being in a continuous heating state. The protection mechanism of the application is comprehensive and effective, and the working safety and reliability of the heating system can be obviously improved.
Drawings
FIG. 1 is a schematic diagram of a prior art heating system;
FIG. 2 is a schematic diagram of a three-level safety protection circuit of the heating system of the present application;
FIG. 3 is a circuit diagram of an embodiment of a general control switch circuit according to the present application;
FIG. 4 is a circuit diagram of an embodiment of a heating control circuit of the present application;
fig. 5 is a circuit diagram of an embodiment of the current monitoring circuit of the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. 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 application.
It will be understood that when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the present application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
As shown in fig. 1, generally in the control of the conventional heating system, a base component includes an ac power supply, a triac, and a heating component, and the on and off of the triac are controlled by a single chip.
In the heating system, a live wire of an alternating current power supply is connected to the heating part through the bidirectional thyristor, and the heating part is connected back to the alternating current power supply through a zero line to form a complete loop. However, once the bidirectional thyristor is short-circuited in the loop, the loop is always conducted, and the heating component is continuously heated to cause potential safety hazard; or when the single chip microcomputer fails or crashes to output continuous high level or low level, the bidirectional controllable silicon can be always conducted, and the heating component is continuously heated to cause potential safety hazards.
Therefore, in one embodiment, a three-level safety protection circuit of the heating system is provided, so that the heating system is comprehensively and effectively protected, and the heating system is prevented from being in a runaway heating state.
The heating system of the present embodiment may be a heating system in an electric appliance such as an electric steamer, an electric oven, a combined steaming and baking machine, or a heating system in other devices including a base component as shown in fig. 1.
As shown in fig. 2, the three-level safety protection circuit of the heating system of this embodiment includes a single chip microcomputer 9, a master control switch circuit 6, a current monitoring circuit 7 and a heating control circuit 8, wherein:
and the master control switch circuit 6 is used for automatically responding to the normal output voltage and the abnormal output voltage of the singlechip 9, switching on or off the alternating current power supply 3 of the heating system according to the normal output voltage and switching off the alternating current power supply 3 of the heating system 1 according to the abnormal output voltage.
The heating control circuit 8 is connected with the bidirectional controllable silicon 5 and used for controlling the work of the heating part 4, the heating control circuit 8 monitors the normal output voltage and the abnormal output voltage of the singlechip 9, the bidirectional controllable silicon 5 is conducted according to the normal output voltage, and the bidirectional controllable silicon 5 is turned off according to the abnormal output voltage.
And the current monitoring circuit 7 is used for detecting abnormal current generated on the heating system 1 and feeding the abnormal current back to the single chip microcomputer 9, and the single chip microcomputer 9 controls the alternating current power supply 3 of the heating system 1 to be switched off through the master control switch circuit 6 after receiving the abnormal current.
The three-level safety protection circuit of the heating system of the embodiment can realize comprehensive and effective protection on the heating system: when the work of the components in the heating system is abnormal (such as the short circuit of the bidirectional triode thyristor), the current monitoring circuit acquires the abnormality and cuts off the alternating current power supply, so that the potential safety hazard caused by continuous heating after the abnormality is prevented; and the silicon controlled rectifier can be turned off and the alternating current power supply can be cut off when the single chip microcomputer is abnormal (for example, the single chip microcomputer fails or is halted), so that the heating system is prevented from being in a continuous heating state.
In order to enable the heating system to still make a correct response when the single chip microcomputer is abnormal, the three-level safety protection circuit provided by the embodiment simplifies the operation of the single chip microcomputer, and the effective execution of the three-level safety protection circuit is ensured by adopting a software and hardware combined mode.
As shown in fig. 3, in an embodiment, the master control switch circuit 6 includes a first anti-lock circuit 10 and a relay K1, the first anti-lock circuit 10 is connected between the single chip microcomputer 9 (not shown in fig. 3) and a coil of the relay K1, and a double normally open contact of the relay K1 is connected in series to a live wire of an ac power supply through connection terminals ACL1 and ACL 2.
The work flow of the master control switch circuit 6 of the present embodiment is as follows:
the first anti-locking circuit 10 receives the square wave normally output by the singlechip 9 and then controls the double normally open contacts of the relay K1 to be closed, so that the alternating current power supply 3 of the heating system is switched on.
Or, the first anti-locking circuit 10 receives the low level normally output by the single chip microcomputer 9 and then controls the double normally open contacts of the relay K1 to be opened, so that the alternating current power supply 3 of the heating system is disconnected.
Or, the first anti-locking circuit 10 receives the continuous high level or low level output abnormally by the singlechip 9 and then controls the double normally open contacts of the relay K1 to be opened, so that the alternating current power supply 3 of the heating system is disconnected.
The first anti-locking circuit 10 has multiple working states according to different outputs of the single chip microcomputer 9, normal control of the single chip microcomputer 9 is guaranteed, meanwhile, the relay K1 can be turned off in time when the single chip microcomputer outputs continuous high level or low level under the fault or dead halt state, and the heating system stops working.
Specifically, the first anti-lock circuit 10 provided in an embodiment includes a resistor R3, a capacitor C1, a diode D1, a capacitor C2, a resistor R4, a resistor R5, and an NPN transistor Q2.
One end of the resistor R3 is connected with the single chip microcomputer 9, the other end of the resistor R3 is connected with the capacitor C1, the other end of the capacitor C1 is connected with the anode of the diode D1, the cathode of the diode D1 is connected with the resistor R4, the other end of the resistor R4 is connected with the base of the NPN triode Q2, one end of the capacitor C2 is connected with the cathode of the diode D1, the other end of the capacitor C2 is grounded, one end of the resistor R5 is connected with the base of the NPN triode Q2, the other end of the resistor R5 is grounded, the emitter of the NPN triode Q2 is grounded, and the collector of the NPN triode Q2 is connected with.
In this embodiment, a working procedure of the first anti-lock circuit 10 is as follows:
after receiving the square waves normally output by the singlechip 9, the square waves are changed into high level through the resistor R3, the capacitor C1, the diode D1 and the capacitor C2, the high level controls the conduction of the triode Q2 through the resistor R4, so that the double normally open contacts of the relay K1 are controlled to be closed, the alternating current power supply 3 of the heating system is switched on, and heating is stopped.
When the bidirectional thyristor is in short circuit, the low level normally output by the singlechip 9 is still low level after passing through the resistor R3, the capacitor C1, the diode D1 and the capacitor C2, and the low level controls the triode Q2 to be switched off after passing through the resistor R4, so that the double normally open contacts of the relay K1 are controlled to be opened, the alternating current power supply 3 of the heating system is disconnected, and heating is stopped.
When the single chip microcomputer 9 is in fault or crashes, the low level or the high level output abnormally by the single chip microcomputer 9 is received, the low level is obtained after the low level is passed through the resistor R3, the capacitor C1, the diode D1, the capacitor C2, the resistor R4 and the resistor R5, the triode Q2 is controlled to be turned off by the low level, so that the double normally open contacts of the relay K1 are controlled to be opened, the alternating current power supply 3 of the heating system is disconnected, and heating is stopped.
In order to further optimize the control of the relay K1, in another embodiment, the master control switch circuit 6 further includes a resistor R2, a resistor R1, a PNP transistor Q1, and a diode D2 connected between the first anti-lock circuit 10 and the relay K1.
One end of resistor R2 is connected with NPN triode Q2's collecting electrode, and the other end of resistor R2 is connected with PNP triode Q1's base, resistor R1 connects between PNP triode Q1's base and projecting pole, PNP triode Q1's projecting pole connects supply voltage VCC1, PNP triode Q1's collecting electrode is connected with diode D2's negative pole, diode D2's positive pole ground connection, relay K1's coil is parallelly connected with diode D2.
In this embodiment, when the NPN transistor Q2 is turned on, the base voltage of the transistor Q1 is pulled high through the resistor R1 and the resistor R2, so that the transistor Q1 is turned on, and the coil of the relay K1 is energized to operate, so that the dual normally open contacts of the relay K1 are closed; when the NPN triode Q2 is turned off, the base of the triode Q1 is at a low voltage, the triode Q1 is turned off, no current is passed through the coil of the relay K1, and the double normally open contacts of the relay K1 are opened.
The double normally open contacts of the relay K1 in this embodiment are connected in series to the live wire of the ac power supply through the connection terminals ACL1 and ACL2, and may be the connection terminal ACL1 connected to the live wire of the ac power supply. It should be noted that the above preferred first anti-lock circuit and the master control switch circuit have the best master control switch effect, and in other embodiments, the anti-lock circuit and the master control switch circuit mentioned in the prior art may also be used.
As shown in fig. 4, in an embodiment, the heating control circuit 8 comprises a second anti-lock circuit 11 connected to the triac 5, BT1 in fig. 4 indicating a triac, i.e. the expressions triac 5 and triac BT1 in the present application are both understood to be triacs.
One operation flow of the heating control circuit 8 of the present embodiment is as follows:
the second anti-locking circuit 11 receives the square wave normally output by the singlechip 9 and then controls the conduction of the bidirectional controllable silicon 5, and the heating part 4 starts to heat.
Or after the second anti-locking circuit 11 receives the continuous high level or the low level output abnormally by the singlechip 9, the bidirectional controllable silicon 5 is controlled to be switched off, and the heating component 4 stops heating.
The heating control circuit 8 can control the conduction of the bidirectional controllable silicon 5 according to the normal output of the single chip microcomputer 9, the heating system works normally, the bidirectional controllable silicon 5 can also be controlled to be switched off when the single chip microcomputer 9 outputs a continuous high level or a low level abnormally under the fault or dead halt state, the work of a heating component is stopped, and the potential safety hazard caused by abnormal continuous heating is avoided.
In an embodiment, the second anti-lock circuit 11 includes a resistor R23, a resistor R17, a capacitor C6, a diode D4, a diode D6, a capacitor C5, a resistor R18, a resistor R15, and a PNP transistor Q3.
Wherein, one end of the resistor R17 is connected with one end of the resistor R23 and then is connected with the singlechip 9, the other end of the resistor R23 is grounded, the other end of the resistor R17 is connected with the capacitor C6, the other end of the capacitor C6 is connected with the cathode of a diode D4, the anode of the diode D4 is connected with a resistor R18, the other end of the resistor R18 is connected with the base of a PNP triode Q3, the anode of the diode D6 is connected with the cathode of the diode D4, the cathode of the diode D6 is connected with a supply voltage VCC2, one end of the capacitor C5 is connected with the anode of the diode D4, the other end of the capacitor C5 is connected with a supply voltage VCC2, one end of the resistor R15 is connected with the base electrode of the PNP triode Q3, the other end of the resistor R15 is connected with the power supply voltage VCC2, the emitting electrode of the PNP triode Q3 is connected with the power supply voltage VCC2, and the collecting electrode of the PNP triode Q3 is used for being connected with the bidirectional triode thyristor 5.
One working flow of the second anti-lock circuit 11 is as follows:
after receiving the square waves normally output by the singlechip 9, the square waves are changed into low level through the resistor R17, the capacitor C6, the diode D6, the diode D4 and the capacitor C5, and the low level controls the conduction of the triode Q3 through the resistor R18, so that the conduction of the bidirectional thyristor BT1 is controlled, and the normal operation of a heating component is ensured.
When the single chip microcomputer 9 is in fault or crashes, the resistor R17, the capacitor C6, the diode D6, the diode D4, the capacitor C5, the resistor R18 and the resistor R15 are changed into high level after receiving the low level or the high level output by the single chip microcomputer 9 abnormally, and the high level controls the triode Q3 to be switched off, so that the bidirectional thyristor BT1 is controlled to be switched off, and the heating component is ensured to stop running.
In order to further optimize the control of the triac BT1, in an embodiment, the heating control circuit 8 further includes an opto-thyristor U2, a resistor R22, a resistor R19, a resistor R20, a resistor R16, a transient suppression diode D5, a capacitor C7, and a resistor R1.
Wherein, the anode of the control end of the optocoupler silicon controlled rectifier U2 is connected with the collector of a PNP triode Q3, the cathode of the control end of the optocoupler silicon controlled rectifier U2 is grounded through a resistor R22, the T2 pole of the optocoupler silicon controlled rectifier U2 is connected with the control pole G of the bidirectional silicon controlled rectifier 5 through a resistor R19, the resistor R16 is connected between the control pole G of the bidirectional silicon controlled rectifier 5 and the T1 pole of the bidirectional silicon controlled rectifier 5, the T1 pole of the bidirectional silicon controlled rectifier 5 is connected to a connecting terminal ACL3, the T2 pole of the bidirectional silicon controlled rectifier 5 is connected with the live wire connecting terminal of the heating component, two ends of the transient suppression diode D5 are respectively connected with the T1 pole and the T2 pole of the bidirectional silicon controlled rectifier 5, one end of the capacitor C7 is connected to a connecting terminal ACL 9, the other end of the capacitor C7 is connected with a resistor R21, the other end of the resistor R21 is connected with the live wire connecting terminal of the heating component, the zero line connecting terminal of the heating member is connected to the zero line of the ac power supply 3.
In this embodiment, when the transistor Q3 is turned on, the triac U2 is controlled to be turned on, and the gate G of the triac BT1 is pulled high by the resistor R16, the resistor R19, and the resistor R20, so that the triac BT1 is turned on. The resistor R21, the capacitor C7 and the transient suppression diode D5 are protection circuits of the bidirectional thyristor BT 1; when the triode Q3 is turned off, the optocoupler silicon controlled rectifier U2 is controlled to be disconnected, the bidirectional silicon controlled rectifier BT1 is disconnected through the resistor R16, the resistor R19 and the resistor R20, and the heating component stops heating, so that safety is guaranteed.
It should be noted that the above preferred second anti-lock circuit and the heating control circuit have the best control effect on the triac, and in other embodiments, the anti-lock circuit and the triac control circuit mentioned in the prior art can be used.
As shown in fig. 5, in an embodiment, the current monitoring circuit 7 includes a capacitor C4, a resistor R11, a resistor R8, a resistor R9, a resistor R12, a capacitor C3, an operational amplifier U1, a resistor R14, a diode D3, a resistor R6, a resistor R7, a resistor R13, a resistor R10, and a current transformer L1.
Wherein, one end of the resistor R8 is connected with the singlechip 9, the other end of the resistor R8 is connected with the resistor R9, the other end of the resistor R9 is connected with the OUTB pin of the operational amplifier U1, a common end of the parallel connection of the capacitor C4 and the resistor R11 is connected with one end of the resistor R8 connected with the singlechip 9, the other common end is grounded, the resistor R12 and the capacitor C3 are connected in series and then are connected in parallel with the resistor R9, one end of the resistor R12 connected with the capacitor C3 is connected with the INB-pin of the operational amplifier U1, one end of the resistor R14 is connected with the INB + pin of the operational amplifier, the other end of the resistor R14 is connected with the cathode of the diode D3, the anode of the diode D3 is connected with the OUTA pin of the operational amplifier U1, one end of the resistor R6 is connected with the OUTA pin of the operational amplifier U1, the other end of the resistor R6 is connected with the INA-pin 6867 and the, one end of the resistor R13 is connected with an INA + pin of the operational amplifier U1, one end of two ends of a secondary side of the current transformer L1 is connected with the other end of the resistor R13, the other end of the two ends of the secondary side of the current transformer L49368 is grounded, the resistor R10 is connected with the secondary side of the current transformer L1 in parallel, a VDD pin of the operational amplifier U1 is connected with a power supply voltage VCC2, a VSS pin of the operational amplifier U1 is grounded, and two ends of a primary side of the current transformer L1 are respectively connected with a connecting terminal ACL 2.
When the bidirectional thyristor 5 is in short circuit, the bidirectional thyristor 5 cannot be turned off, the heating part can continuously heat, under the condition, the working current in the heating system can be different from the value in normal working, at the moment, the live wire of the alternating current power supply passes through the current transformer L1, the resistor R10 converts the sampled abnormal current signal into a voltage signal, and the resistor R7, the resistor R13, the resistor R6 and the operational amplifier U1 form an amplifying circuit to amplify the collected voltage signal; then a following circuit is formed by the capacitor D3, the resistor R14, the operational amplifier U1, the capacitor C3, the resistor R9 and the resistor R12, and signal waveforms are optimized; and finally, the high-frequency and low-frequency interference in the signals is suppressed through a filter circuit consisting of a resistor R8, a resistor R11 and a capacitor C4, and finally obtained abnormal signals are transmitted to the singlechip 9. The singlechip 9 outputs low level after detecting the abnormal signal, so that the master control switch circuit 6 cuts off the power supply of the heating system, the bidirectional controllable silicon 5 stops working, the heating system is forced to stop working, and the safety is ensured.
When the bidirectional controllable silicon 5 works normally, the detection flow of the current monitoring circuit 7 is the same as that described above, and the difference is that the single chip microcomputer 9 receives a normal signal, and the single chip microcomputer 9 does not act. It should be noted that the above preferred current monitoring circuit is provided for optimal circuit monitoring and feedback effects, and in other embodiments, the circuit monitoring circuit mentioned in the prior art may be used.
The third level safety protection circuit of the heating system of the present application is further detailed by experiments below.
Example 1
This embodiment sets up 4 groups of subjects, and the first group does not have any protection, and the second group only is the protection of current monitoring circuit 7, and the third group has total control switch circuit 6 and current monitoring circuit 7, and the fourth group is the tertiary safety protection circuit of this application. The basic components for controlling the heating system are the same, and the states of the heating system under the two conditions of the short circuit of the bidirectional controllable silicon, the fault of the single chip microcomputer or the crash are recorded as shown in table 1.
TABLE 1 heating System State
| Bidirectional thyristor short circuit | Fault or dead halt of single-chip microcomputer | |
| First group | Can not cut off AC power supply | The bidirectional thyristor can not be switched off, and the alternating current power supply can not be switched off |
| Second group | Can not cut off AC power supply | The bidirectional thyristor can not be switched off, and the alternating current power supply can not be switched off |
| Third group | Can cut off AC power supply | The bidirectional thyristor can not be switched off, and the alternating current power supply can not be switched off |
| Fourth group | Can cut off AC power supply | Can turn off bidirectional thyristor and cut off AC power supply |
As can be seen from the table 1, the three-level safety protection circuit is timely and effective in protection of the heating system, and reliability and safety of the heating system are greatly improved.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (8)
1. The utility model provides a heating system's tertiary safety protection circuit, heating system (1) includes alternating current power supply (3), bidirectional thyristor (5) and heating part (4), its characterized in that, heating system's tertiary safety protection circuit includes singlechip (9), total control switch circuit (6), current monitoring circuit (7) and heating control circuit (8), wherein:
the master control switch circuit (6) is used for automatically responding to the normal output voltage and the abnormal output voltage of the singlechip (9), switching on or off the alternating current power supply (3) of the heating system according to the normal output voltage and switching off the alternating current power supply (3) of the heating system (1) according to the abnormal output voltage;
the heating control circuit (8) is connected with the bidirectional controllable silicon (5) and used for controlling the work of the heating component (4), the heating control circuit (8) monitors the normal output voltage and the abnormal output voltage of the singlechip (9), the bidirectional controllable silicon (5) is switched on according to the normal output voltage, and the bidirectional controllable silicon (5) is switched off according to the abnormal output voltage;
the current monitoring circuit (7) is used for detecting abnormal current generated on the heating system (1) and feeding the abnormal current back to the single chip microcomputer (9), and the single chip microcomputer (9) controls the alternating current power supply (3) of the heating system (1) to be switched off through the master control switch circuit (6) after receiving the abnormal current.
2. Three-level safety protection circuit of a heating system according to claim 1, characterized in that said master control switch circuit (6) comprises a first anti-lock circuit (10) and a relay K1, said first anti-lock circuit (10) being connected between a single-chip microcomputer (9) and the coil of a relay K1, the double normally open contact of said relay K1 being connected in series to the live line of the alternating current power supply through terminals ACL1, ACL 2;
the first anti-locking circuit (10) receives the square waves normally output by the singlechip (9) and then controls the double normally open contacts of the relay K1 to be closed, so that an alternating current power supply (3) of the heating system is conducted;
or the first anti-locking circuit (10) receives the low level normally output by the singlechip (9) and then controls the double normally open contacts of the relay K1 to be opened, so that the alternating current power supply (3) of the heating system is disconnected;
or the first anti-locking circuit (10) controls the double normally open contacts of the relay K1 to be opened after receiving the continuous high level or the low level output abnormally by the singlechip (9), so that the alternating current power supply (3) of the heating system is disconnected.
3. Three-level safety protection circuit for a heating system according to claim 2, characterized in that said first anti-blocking circuit (10) comprises a resistor R3, a capacitor C1, a diode D1, a capacitor C2, a resistor R4, a resistor R5 and an NPN transistor Q2;
one end of the resistor R3 is connected with the single chip microcomputer (9), the other end of the resistor R3 is connected with the capacitor C1, the other end of the capacitor C1 is connected with the anode of the diode D1, the cathode of the diode D1 is connected with the resistor R4, the other end of the resistor R4 is connected with the base of the NPN triode Q2, one end of the capacitor C2 is connected with the cathode of the diode D1, the other end of the capacitor C2 is grounded, one end of the resistor R5 is connected with the base of the NPN triode Q2, the other end of the resistor R5 is grounded, the emitter of the NPN triode Q2 is grounded, and the collector of the NPN triode Q2 is connected with the.
4. A three-level safety protection circuit for a heating system according to claim 3, wherein the general control switch circuit (6) further comprises a resistor R2, a resistor R1, a PNP transistor Q1 and a diode D2 connected between the first anti-lock circuit (10) and the relay K1;
one end of the resistor R2 is connected with the collector of the NPN triode Q2, the other end of the resistor R2 is connected with the base of the PNP triode Q1, the resistor R1 is connected between the base and the emitter of the PNP triode Q1, the emitter of the PNP triode Q1 is connected with the power supply voltage VCC1, the collector of the PNP triode Q1 is connected with the cathode of the diode D2, the anode of the diode D2 is grounded, and the coil of the relay K1 is connected with the diode D2 in parallel.
5. A three-level safety protection circuit for heating systems, as in claim 1, characterized in that said heating control circuit (8) comprises a second anti-blocking circuit (11) connected to the triac (5);
the second anti-locking circuit (11) receives the square waves normally output by the singlechip (9) and then controls the conduction of the bidirectional controllable silicon (5), and the heating component (4) starts to heat;
or the second anti-locking circuit (11) controls the bidirectional controllable silicon (5) to be switched off after receiving the continuous high level or the low level output abnormally by the singlechip (9), and the heating component (4) stops heating.
6. Three-level safety protection circuit for a heating system according to claim 5, characterized in that said second anti-blocking circuit (11) comprises a resistor R23, a resistor R17, a capacitor C6, a diode D4, a diode D6, a capacitor C5, a resistor R18, a resistor R15, a PNP transistor Q3;
one end of the resistor R17 and one end of the resistor R23 are connected and then are connected with the singlechip (9), the other end of the resistor R23 is grounded, the other end of the resistor R17 is connected with the capacitor C6, the other end of the capacitor C6 is connected with the cathode of a diode D4, the anode of the diode D4 is connected with a resistor R18, the other end of the resistor R18 is connected with the base of a PNP triode Q3, the anode of the diode D6 is connected with the cathode of the diode D4, the cathode of the diode D6 is connected with a supply voltage VCC2, one end of the capacitor C5 is connected with the anode of the diode D4, the other end of the capacitor C5 is connected with a supply voltage VCC2, one end of the resistor R15 is connected with the base electrode of the PNP triode Q3, the other end of the resistor R15 is connected with the power supply voltage VCC2, the emitting electrode of the PNP triode Q3 is connected with a supply voltage VCC2, and the collecting electrode of the PNP triode Q3 is used for being connected with a bidirectional thyristor (5).
7. Three-level safety protection circuit for a heating system according to claim 6, characterized in that said heating control circuit (8) further comprises opto-thyristor U2, resistor R22, resistor R19, resistor R20, resistor R16, transient suppression diode D5, capacitor C7 and resistor R1;
the anode of the control end of the optocoupler silicon controlled rectifier U2 is connected with the collector of a PNP triode Q3, the cathode of the control end of the optocoupler silicon controlled rectifier U2 is grounded through a resistor R22, the T2 pole of the optocoupler silicon controlled rectifier U2 is connected with the control pole G of the bidirectional silicon controlled rectifier (5) through a resistor R19, the resistor R16 is connected between the control pole G of the bidirectional silicon controlled rectifier (5) and the T1 pole of the bidirectional silicon controlled rectifier (5), the T1 pole of the bidirectional silicon controlled rectifier (5) is connected to a connecting terminal ACL3, the T2 pole of the bidirectional silicon controlled rectifier (5) is connected with the live wire connecting terminal of the heating component, two ends of the transient suppression diode D5 are respectively connected with the T1 pole and the T2 pole of the bidirectional silicon controlled rectifier (5), one end of the capacitor C7 is connected to a connecting terminal ACL3, the other end of the capacitor C7 is connected with a resistor R21, the other end of the resistor R21 is connected with the live wire connecting terminal of the heating component, the, the zero line connecting terminal of the heating component is connected with the zero line of the alternating current power supply (3).
8. Three-level safety protection circuit for a heating system according to claim 1, characterized in that said current monitoring circuit (7) comprises a capacitor C4, a resistor R11, a resistor R8, a resistor R9, a resistor R12, a capacitor C3, an operational amplifier U1, a resistor R14, a diode D3, a resistor R6, a resistor R7, a resistor R13, a resistor R10 and a current transformer L1;
one end of the resistor R8 is connected with a singlechip (9), the other end of the resistor R8 is connected with a resistor R9, the other end of the resistor R9 is connected with an OUTB pin of an operational amplifier U1, a common end of the resistor C4 and the resistor R11 after being connected in parallel is connected with one end of the resistor R8 connected with the singlechip (9), the other common end of the resistor R8 is grounded, the resistor R12 and the capacitor C3 are connected in series and then are connected in parallel with the resistor R9, one end of the resistor R12 connected with a capacitor C3 is connected with an INB-pin of an operational amplifier U1, one end of the resistor R14 is connected with an INB + pin of the operational amplifier, the other end of the resistor R14 is connected with a cathode of a diode D3, an anode of a diode D3 is connected with an OUTA pin of the operational amplifier U1, one end of the resistor R6 is connected with an OUTA pin of the operational amplifier U1, the other end of the resistor R6 is respectively connected with an INA-, one end of the resistor R13 is connected with an INA + pin of the operational amplifier U1, one end of two ends of a secondary side of the current transformer L1 is connected with the other end of the resistor R13, the other end of the two ends of the secondary side of the current transformer L49368 is grounded, the resistor R10 is connected with the secondary side of the current transformer L1 in parallel, a VDD pin of the operational amplifier U1 is connected with a power supply voltage VCC2, a VSS pin of the operational amplifier U1 is grounded, and two ends of a primary side of the current transformer L1 are respectively connected with a connecting terminal ACL 2.
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