CN108024405A - Electromagnetic heating system and its protective device - Google Patents
Electromagnetic heating system and its protective device Download PDFInfo
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- CN108024405A CN108024405A CN201610958445.XA CN201610958445A CN108024405A CN 108024405 A CN108024405 A CN 108024405A CN 201610958445 A CN201610958445 A CN 201610958445A CN 108024405 A CN108024405 A CN 108024405A
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/02—Induction heating
- H05B6/06—Control, e.g. of temperature, of power
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B2206/00—Aspects relating to heating by electric, magnetic, or electromagnetic fields covered by group H05B6/00
- H05B2206/02—Induction heating
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- Control Of Resistance Heating (AREA)
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Abstract
The invention discloses a kind of electromagnetic heating system and its protective device, which includes：Resonant element, it includes heating coil, resonant capacitance and switching tube；Current detecting unit, its input terminal are connected with resonant element, it is used to be detected the resonance current of resonant element, and generate protection signal when resonance current is more than predetermined current threshold；Control signal receiving terminal, it is used to receive PPG control signals；Driving unit; its first input end is connected with control signal receiving terminal; its second input terminal is connected with the output terminal of current detecting unit; its output terminal is connected with the control terminal of switching tube; it is used to be switched on or off according to PPG control signal driving switch pipes when the number for receiving protection signal is not up to preset times threshold value, and driving switch pipe turns off when the number for receiving protection signal reaches preset times threshold value.Thus, when resonance current is abnormal, driving switch pipe turns off, and prevents switching tube to be continually switched on or off, protection switch pipe.
Description
Technical field
The present invention relates to household electrical appliance technical field, protective device and one kind electricity of more particularly to a kind of electromagnetic heating system
Magnetic heating system.
Background technology
In the related art, electromagnetic heating system exports pwm pulse signal with driving power switching tube according to target power
Work, and the operating current for flowing through switching tube is limited in predetermined current threshold, with protection switch pipe.
It is less than normal, electric if there is following abnormal conditions, such as voltage sample value but correlation technique has the following disadvantages
Sampling circuit open circuit or current sampling circuit exception etc. are pressed, then predetermined current threshold can be caused to become larger, control unit will increase
Add the pwm signal of output, and stop output pwm signal after operating current reaches predetermined current threshold, and in preset time
Inspection pot work is re-started afterwards.Therefore, current control can be caused out of control, there is the phenomenon of interruption heating in electromagnetic heating system,
And switching tube can periodically produce inspection pot noise, increase the live load of switching tube, the performance of system is poor, reliably
Property is relatively low.
The content of the invention
It is contemplated that solve at least some of the technical problems in related technologies.For this reason, the present invention
One purpose is to propose a kind of protective device of electromagnetic heating system, which can be effectively prevented from caused by circuit abnormality
Current control is out of control, protection switch pipe.
It is another object of the present invention to propose a kind of electromagnetic heating system.
To reach above-mentioned purpose, a kind of protective device for electromagnetic heating system that one aspect of the present invention embodiment proposes, bag
Include：Resonant element, the resonant element include heating coil, resonant capacitance and switching tube；Current detecting unit, the electric current inspection
The input terminal for surveying unit is connected with the resonant element, and the current detecting unit is used for the resonance current to the resonant element
It is detected, and protection signal is generated when the resonance current is more than predetermined current threshold；Control signal receiving terminal, the control
Signal receiving end processed is used to receive PPG control signals；Driving unit, the first input end of the driving unit are believed with the control
Number receiving terminal is connected, and the second input terminal of the driving unit is connected with the output terminal of the current detecting unit, the driving
The output terminal of unit is connected with the control terminal of the switching tube, and the driving unit is used to receive time of the protection signal
Drive the switching tube to be switched on or off according to the PPG control signals when number is not up to preset times threshold value, and receiving
The number of the protection signal drives the switching tube to turn off when reaching the preset times threshold value.
The protective device of the electromagnetic heating system proposed according to embodiments of the present invention, driving of the resonant element in driving unit
Lower progress resonance heating, current detecting unit is detected the resonance current of resonant element, and is more than in resonance current and presets
Generate protection signal during current threshold, driving unit when the number for receiving protection signal is not up to preset times threshold value according to
The PPG control signal driving switch pipes that control signal receiving terminal receives are switched on or off, and are receiving time of protection signal
Driving switch pipe shut-off when number reaches preset times threshold value.Thus, the protective device of the electromagnetic heating system of the embodiment of the present invention
When the resonance current detected is abnormal, driving switch pipe turns off, current control caused by so as to avoid circuit abnormality
It is out of control, prevent switching tube to be continually switched on or off when occurring abnormal, prevent inspection pot noise, reduce the work of switching tube
Load, protection switch pipe, lifts the reliability of product.
According to one embodiment of present invention, the current detecting unit includes：Current sampling circuit, the current sample
Circuit is connected with the resonant element, and the current sampling circuit is used for the resonance current for sampling the resonant element；At electric current
Manage circuit, the current processing circuits are connected with the current sampling circuit, and the current processing circuits are for sampling
The resonance current is handled to generate current processing signal；Comparison circuit, the comparison circuit respectively with the electric current
Reason circuit is connected with the second input terminal of the driving unit, and the comparison circuit is used to sentence according to the current processing signal
Break when the resonance current is more than the predetermined current threshold and generate the protection signal.
According to one embodiment of present invention, the current sampling circuit includes sampling resistor, and the sampling resistor is set
In the resonant element, one end ground connection of the sampling resistor, the other end of the sampling resistor and the current processing are electric
Road is connected.
According to one embodiment of present invention, the current processing circuits include amplifying circuit, and the amplifying circuit includes：
First resistor, one end of the first resistor are connected with the current sampling circuit；Second resistance, one end of the second resistance
It is connected with the other end of the first resistor and there is first node；First operational amplifier, first operational amplifier
Positive input terminal is connected with the first node, and the output terminal of first operational amplifier is another with the second resistance respectively
End is connected with the comparison circuit；3rd resistor, one end of the 3rd resistor and the negative input of first operational amplifier
End is connected, the other end ground connection of the 3rd resistor.
According to one embodiment of present invention, the current processing circuits further include isolation circuit, and the isolation circuit connects
It is connected between the amplifying circuit and the current sampling circuit, the isolation circuit includes：4th resistance, the 4th resistance
One end be connected with the current sampling circuit；First capacitance, one end of first capacitance are another with the 4th resistance
End is connected and has section point, and the other end of first capacitance is grounded；Second operational amplifier, second operation amplifier
The negative input end of device is connected with the section point, and the output terminal of second operational amplifier is put with second computing respectively
The positive input terminal of big device is connected with one end of the first resistor.
According to one embodiment of present invention, the comparison circuit includes：3rd operational amplifier, the 3rd operational amplifier
Positive input terminal be connected with the current processing circuits, the negative input end of the 3rd operational amplifier is with providing reference voltage
Reference voltage provides circuit and is connected, the output terminal of the 3rd operational amplifier and the second input terminal phase of the driving unit
Even.
According to one embodiment of present invention, the driving unit includes：Counter, the counter are used for receiving
Protection signal counted；Push-pull circuit, the output terminal of the push-pull circuit are connected with the control terminal of the switching tube；First
Control circuit, the input terminal of the first control circuit are connected with the control signal receiving terminal, the first control circuit
Output terminal is connected with the input terminal of the push-pull circuit, and the first control circuit is used for according to the PPG control signals and leads to
Crossing the push-pull circuit controls the switching tube to be switched on or off；Second control circuit, the input terminal of the second control circuit
It is connected with the counter, the output terminal of the second control circuit is connected with the input terminal of the push-pull circuit, and described second
Control circuit is used for when the counting of the counter reaches the preset times threshold value by described in push-pull circuit control
Switching tube turns off.
According to one embodiment of present invention, the second control circuit includes：5th resistance, the one of the 5th resistance
End is connected with the counter；6th resistance, one end of the 6th resistance is connected with the other end of the 5th resistance, described
The other end ground connection of 6th resistance, has the 3rd node between the 6th resistance and the 5th resistance；7th resistance, it is described
One end of 7th resistance is connected with default power supply；First triode, the base stage of first triode and the 3rd node phase
Even, the collector of first triode respectively with the other end of the 7th resistance and the input terminal phase of the push-pull circuit
Even, the emitter ground connection of first triode.
According to one embodiment of present invention, the first control circuit shares the described 7th with the second control circuit
Resistance, the first control circuit include：8th resistance, one end and the control signal receiving terminal phase of the 8th resistance
Even；9th resistance, one end of the 9th resistance are connected with default power supply, and the other end of the 9th resistance is believed with the control
Number receiving terminal is connected；Second triode, the base stage of second triode are connected with the other end of the 8th resistance, and described
The collector of two triodes is connected with the other end of the 7th resistance and the input terminal of the push-pull circuit respectively, and described second
The emitter ground connection of triode.
A specific embodiment according to the present invention, the preset times threshold value can be 10, and the counter can be asynchronous
Decade counter.
To reach above-mentioned purpose, a kind of electromagnetic heating system that another aspect of the present invention embodiment proposes, including it is described
The protective device of electromagnetic heating system.
The electromagnetic heating system proposed according to embodiments of the present invention, it is humorous what is detected by above-mentioned electromagnetic heating system
Driving switch pipe turns off when the electric current that shakes is abnormal, and current control is out of control caused by so as to avoid circuit abnormality, prevents out
Close when pipe occurs abnormal and be continually switched on or off, prevent inspection pot noise, reduce the live load of switching tube, protection switch
Pipe, lifts the reliability of product.
Brief description of the drawings
Fig. 1 is the block diagram of the protective device of electromagnetic heating system according to embodiments of the present invention；
Fig. 2 is the circuit diagram of the protective device of electromagnetic heating system according to an embodiment of the invention；And
Fig. 3 is the block diagram of electromagnetic heating system according to embodiments of the present invention.
Reference numeral：
Resonant element 10, current detecting unit 20, control signal receiving terminal 30 and driving unit 40；
Heating coil L0, resonant capacitance C0 and switching tube 101；
Power supply circuit 50, power supply 60, rectifier 501 and filter module 502；
Filter inductance L502 and filter capacitor C502；
Current sampling circuit 201, current processing circuits 202 and comparison circuit 203；
Sampling resistor R0, amplifying circuit 202A, first resistor R1, second resistance R2, the first operational amplifier U1 and the 3rd
Resistance R3；
Isolation circuit 202B, the 4th resistance R4, the first capacitance C1 and the second operational amplifier U2；
3rd operational amplifier U3；
Counter 401, push-pull circuit 402, first control circuit 403 and second control circuit 404；
5th resistance R5, the 6th resistance R6, the 7th resistance R7 and the first triode Q1；
8th resistance R8, the 9th resistance R9 and the second triode Q2；
Tenth resistance R10, the 3rd triode Q3 and the 4th triode Q4；
The protective device 100 of electromagnetic heating system 200, electromagnetic heating system.
Embodiment
The embodiment of the present invention is described below in detail, the example of the embodiment is shown in the drawings, wherein from beginning to end
Same or similar label represents same or similar element or has the function of same or like element.Below with reference to attached
The embodiment of figure description is exemplary, it is intended to for explaining the present invention, and is not considered as limiting the invention.
Below with reference to the accompanying drawings come describe the embodiment of the present invention proposition electromagnetic heating system and its protective device.
Fig. 1 is the block diagram of the protective device of electromagnetic heating system according to embodiments of the present invention.As shown in Figure 1,
The protective device of the electromagnetic heating system includes：Resonant element 10, current detecting unit 20, control signal receiving terminal 30 and driving
Unit 40.
Wherein, resonant element 10 includes heating coil L0, resonant capacitance C0 and switching tube 101, wherein, heating coil L0 and
Resonant capacitance C0 can be connected in parallel；The input terminal of current detecting unit 20 is connected with resonant element 10, and current detecting unit 20 is used
It is detected in the resonance current to resonant element 10, and protection signal is generated when resonance current is more than predetermined current threshold；
Control signal receiving terminal 30 is used to receive PPG control signals；The first input end IN1 of driving unit 40 and control signal receiving terminal
30 are connected, and the second input terminal IN2 of driving unit 40 is connected with the output terminal of current detecting unit 20, the output of driving unit 40
End is connected with the control terminal G of switching tube 101, and driving unit 40 is used to be not up to preset times in the number for receiving protection signal
It is switched on or off during threshold value according to PPG control signal driving switch pipe 101, and reaches default in the number for receiving protection signal
Driving switch pipe 101 turns off during frequency threshold value.
A specific embodiment according to the present invention, as illustrated in fig. 1 and 2, switching tube 101 can be that IGBT manages (Insulated
Gate Bipolar Transistor, insulated gate bipolar transistor).Wherein, the control pole G of IGBT pipes and driving unit 40
Output terminal be connected, the collector C of IGBT pipes is connected with one end of heating coil L0 in parallel and resonant capacitance C0, IGBT pipes
Emitter E is grounded, and the other end of heating coil L0 in parallel and resonant capacitance C0 are connected with power supply circuit 50.
According to one embodiment of present invention, as shown in Fig. 2, the protective device of electromagnetic heating system further includes power supply circuit
50, wherein, power supply circuit 50 includes：Rectifier 501 and filter module 502, wherein, the of such as electric main of power supply 60
One end AC1 is connected with the first input end of rectifier 501, the second end AC2 of power supply 60 and the second input of rectifier 501
End be connected, the first output terminal of rectifier 501 is connected with the input terminal of filter module 502, the second output terminal of rectifier 501 and
Current detecting unit 20 is connected, and rectifier 501 is used to carry out rectification processing to electric main, and by the direct current electricity output after rectification
To filter module 502；The output terminal of filter module 502 is connected with the other end of heating coil L0 in parallel, resonant capacitance C0, filters
Ripple module 502 is used to be filtered processing to the direct current after rectification, wherein, filter module 502 includes：Filter inductance L502 and
Filter capacitor C502.
Specifically, in the course of work of electromagnetic heating system, electric main passes through rectifier 501 and filter module
Direct current is exported after 502 processing, to provide stable DC for resonant element 10.Heater is carried out in resonant element 10
When making, current detecting unit 20 can detect the resonance current for flowing through resonant element 10 in real time, and resonance current is handled, with
And judge whether resonance current is more than predetermined current threshold, when the electric current of resonant element 10 is less than or equal to predetermined current threshold,
Illustrate circuit no exceptions, current detecting unit 20 exports non-protected signal such as low level, and driving unit 40 is receiving
The PPG control signal driving switch pipe 101 received after non-protected signal according to control signal receiving terminal 30 is switched on or off, from
And control resonant element 10 to be heated, electromagnetic heating system normal work.When the electric current of resonant element 10 is more than predetermined current
During threshold value, illustrate circuit abnormal, 20 output protection signal such as high level of current detecting unit, driving unit 40 is to receiving
To protection signal counted, and whether the number of protection signal for judging to receive reaches preset times threshold value such as ten
Secondary, if it is determined that the number of the protection signal received is not up to preset times threshold value, driving unit 40 is then according to control signal
The PPG control signal driving switch pipe 101 that receiving terminal 30 receives is switched on or off, so as to control resonant element 10 to be added
Heat；If it is determined that the number of the protection signal received reaches preset times threshold value, then driving switch pipe 101 closes driving unit 40
It is disconnected, so that resonant element 10 stops being heated.
Thus, by the protective device of the electromagnetic heating system of the embodiment of the present invention, when resonance current is abnormal driving open
Pipe shut-off is closed, current control is out of control caused by so as to avoid circuit abnormality, is continually opened when preventing switching tube from occurring abnormal
Logical or shut-off, prevents inspection pot noise, reduces the live load of switching tube, protection switch pipe, lifts the reliability of product.
According to one embodiment of present invention, as shown in Fig. 2, current detecting unit 20 includes：Current sampling circuit 201,
Current processing circuits 202 and comparison circuit 203, wherein, current sampling circuit 201 is connected with resonant element 10, current sample electricity
Road 201 is used for the resonance current of sampling harmonic unit 10；Current processing circuits 202 are connected with current sampling circuit 201, at electric current
Reason circuit 202 is used to handle to generate current processing signal the resonance current sampled；Comparison circuit 203 respectively with electricity
Stream process circuit 202 is connected with the second input terminal of driving unit, and comparison circuit 203 is used to judge according to current processing signal
The electric current of resonant element 10 generates protection signal when being more than predetermined current threshold.
According to one embodiment of present invention, as shown in Fig. 2, current sampling circuit 201 includes sampling resistor R0, sampling electricity
Resistance R0 is arranged in resonant element 10, one end of sampling resistor R0 ground connection, the hair of one end of sampling resistor R0 also with switching tube 101
Emitter-base bandgap grading E is connected, and the other end of sampling resistor R0 is connected with current processing circuits 202, the other end of sampling resistor R0 also with power supply
Second output terminal of rectifier 501 is connected in circuit 50.
Specifically, filter capacitor C502, heating coil L0, resonant capacitance C0 and switching tube 101 form circuit, and electric current is adopted
Sample circuit 201 samples the electric current for flowing through switching tube 101 by sampling resistor R0, and the electric current that will flow through sampling resistor R0
Voltage signal is converted into export to current processing unit 202.
According to one embodiment of present invention, as shown in Fig. 2, current processing circuits 202 include amplifying circuit 202A, amplification
Circuit 202A includes：First resistor R1, second resistance R2, the first operational amplifier U1 and 3rd resistor R3, wherein, first resistor
One end of R1 is connected with current sampling circuit 201；One end of second resistance R2 is connected and has with the other end of first resistor R1
First node；The positive input terminal of first operational amplifier U1+be connected with first node, the output terminal point of the first operational amplifier U1
It is not connected with the other end and comparison circuit 203 of second resistance R2；One end of 3rd resistor R3 is with the first operational amplifier U1's
Negative input end-be connected, the other end ground connection of 3rd resistor R3.
According to one embodiment of present invention, as shown in Fig. 2, current processing circuits 202 further include isolation circuit 202B, every
It is connected to from circuit 202B between amplifying circuit 202A and current sampling circuit 201, isolation circuit 202B includes：4th resistance
R4, the first capacitance C1 and the second operational amplifier U2, wherein, one end of the 4th resistance R4 is connected with current sampling circuit 201；The
One end of one capacitance C1 is connected with the other end of the 4th resistance R4 and has section point, and the other end of the first capacitance C1 is grounded；
The negative input end of second operational amplifier U2 is connected with section point, and the output terminal of the second operational amplifier U2 is transported with second respectively
The positive input terminal for calculating amplifier U2 is connected with one end of first resistor R1.
Specifically, the 4th resistance R4, the first capacitance C1 and the second operational amplifier U2 form voltage follower, to improve
The antijamming capability of signal.In an embodiment of the present invention, the 4th resistance R4 and the first capacitance C1 compositions level-one RC wave filters, should
RC wave filters receive the voltage signal that current sampling circuit 201 exports, and processing is filtered to voltage signal, and by filtering
Voltage signal after reason is exported to the second operational amplifier U2, so as to eliminate the interference of external signal, improves input impedance, and
Signal isolation can be achieved.
Further, the second operational amplifier U2 exports the voltage signal after filtering process to amplifying circuit 202A, puts
Big circuit 202A docks the voltage signal after received filtering process and carries out Linear Amplifer, and by the voltage signal after enhanced processing
Export to comparison circuit 203, wherein, the amplification factor A=1+R2/R1 of amplifying circuit 202A.
According to one embodiment of present invention, as shown in Fig. 2, comparison circuit 203 includes：3rd operational amplifier U3, its
In, the positive input terminal of the 3rd operational amplifier U3 is connected with current processing circuits 202, the negative input end of the 3rd operational amplifier U3
Reference voltage with providing reference voltage provides circuit 203A and is connected, output terminal and the driving unit 40 of the 3rd operational amplifier U3
The second input terminal be connected.
Specifically, comparison circuit 203 carries the magnitude of voltage and reference voltage of the amplifying circuit 202A voltage signals exported
It is compared for the circuit 203A reference voltages provided, to judge whether the electric current of resonant element 10 is more than predetermined current threshold,
And generate protection signal when the electric current of resonant element 10 is more than predetermined current threshold.Wherein, when the normal work of electromagnetic heating system
When making, the magnitude of voltage of the voltage signal after the enhanced processing that the positive input terminal of the 3rd operational amplifier U3 receives is less than or equal to the
The magnitude of voltage for the reference voltage that the negative input end of three operational amplifier U3 receives, the i.e. electric current of resonant element 10 are less than or equal to pre-
If current threshold, at this time, comparison circuit 203 exports low level (non-protected signal) to the second input terminal of driving unit 40；When
When the circuit of electromagnetic heating system breaks down, the upper pressure difference of sampling resistor R0 becomes larger, by amplifying circuit 202A and every
After circuit 202B processing, the electricity of the voltage signal after the enhanced processing that receives of positive input terminal of the 3rd operational amplifier U3
Electric current of the pressure value more than the magnitude of voltage, i.e. resonant element 10 of the reference voltage that the negative input end of the 3rd operational amplifier U3 receives
More than predetermined current threshold, at this time, comparison circuit 203 exports high level to the second input terminal of driving unit 40, produces one
Rising edge signal, current detecting unit 20 are exported the rising edge signal as protection signal to the second input of driving unit 40
End, with trigger drive unit 40.
According to one embodiment of present invention, as shown in Fig. 2, driving unit 40 includes：Counter 401, push-pull circuit
402nd, first control circuit 403 and second control circuit 404.
Wherein, counter 401 is counted for docking received protection signal, the input terminal and electric current of counter 401
The output terminal of detection unit 20 is connected, to receive the pulse signal of the output of current detecting unit 20；The output terminal of push-pull circuit 402
It is connected with the control terminal G of switching tube 101；The input terminal IN1 of first control circuit 403 is connected with control signal receiving terminal 30, the
The output terminal of one control circuit 403 is connected with the input terminal of push-pull circuit 402, and first control circuit 403 is used to be controlled according to PPG
Signal is simultaneously switched on or off by 402 controlling switch pipe 101 of push-pull circuit；The input terminal IN2 of second control circuit 404 is with counting
The output terminal of device 401 is connected, and the output terminal of second control circuit 404 is connected with the input terminal of push-pull circuit 402, the second control electricity
Road 404 is used to turn off by 402 controlling switch pipe 101 of push-pull circuit when the counting of counter 401 reaches preset times threshold value.
A specific embodiment according to the present invention, preset times threshold value can be 10, and counter 401 can be the asynchronous decimal system
Counter, such as the asynchronous decade counter being made of 74LS290, wherein, counter 401 can be triggered by rising edge signal,
When the number of the accumulative pulse signal collected of counter 401 reaches 10 times, counter 401 produces carry signal, at this time, meter
The output terminal of number device 401 is high level by low level upset.
Specifically, the electric current for flowing through sampling resistor R0 is converted into voltage signal by current detecting unit 20, and will processing
Voltage signal afterwards is as output of pulse signal to counter 401, and when circuit no exceptions, current detecting unit 20 exports
Pulse signal be low level (non-protected signal) so that counter 401 export low level, first control circuit 403 is according to PPG
Control signal is simultaneously switched on or off by 402 controlling switch pipe 101 of push-pull circuit；When circuit abnormal, current detecting list
The resonance current increase that member 20 detects, and it is more than one rising edge letter of predetermined current threshold generation in the electric current of resonant element 10
Number i.e. protection signal.
Further, when the input terminal of counter 401 receives the rising edge signal of the output of current detecting unit 20, meter
The counts of number device 401 add 1, and determine whether that the accumulative rising edge signal received of nonce counter 401 protects letter
Number number whether reach preset times threshold value (such as 10 times).According to the operation principle of asynchronous decade counter, work as counting
When the accumulative rising edge signal i.e. number of protection signal received of device 401 reaches 10 times, counter 401 exports high level to the
Two control circuits 404, at this time circuit be in abnormality, second control circuit 404 passes through 402 controlling switch pipe of push-pull circuit
101 shut-offs；When the accumulative rising edge signal i.e. number of protection signal received of counter 401 is not up to 10 times, counter
401 output low levels are to second control circuit 404, and first control circuit 403 is according to PPG control signals and by recommending electricity at this time
402 controlling switch pipe 101 of road is switched on or off.
According to one embodiment of present invention, as shown in Fig. 2, second control circuit 404 includes：5th resistance R5, the 6th
Resistance R6, the 7th resistance R7 and the first triode Q1, wherein, one end of the 5th resistance R5 is connected with counter 401；6th resistance
One end of R6 is connected with the other end of the 5th resistance R5, the other end ground connection of the 6th resistance R6, the 6th resistance R6 and the 5th resistance
There is the 3rd node between R5；One end of 7th resistance R7 is connected with default power supply VCC；The base stage B of first triode Q1 and
Three nodes are connected, the collector C of the first triode Q1 respectively with the other end of the 7th resistance R7 and the input terminal of push-pull circuit 402
It is connected, the emitter E ground connection of the first triode Q1.
According to one embodiment of present invention, as shown in Fig. 2, first control circuit 403 is shared with second control circuit 404
7th resistance R7, first control circuit 403 include：8th resistance R8, the 9th resistance R9 and the second triode Q2, wherein, the 8th
One end of resistance R8 is connected with control signal receiving terminal 30；One end of 9th resistance R9 is connected with default power supply VCC, the 9th resistance
The other end of R9 is connected with control signal receiving terminal 30；The base stage B of second triode Q2 is connected with the other end of the 8th resistance R8,
The collector C of second triode Q2 is connected with the other end of the 7th resistance R7 and the input terminal of push-pull circuit 402 respectively, and the two or three
The emitter E ground connection of pole pipe Q2.
According to one embodiment of present invention, as shown in Fig. 2, push-pull circuit 402 includes：Tenth resistance R10, the three or three pole
Pipe Q3 and the 4th triode Q4, wherein, one end of the tenth resistance R10 is connected with default power supply VCC；The base stage of 3rd triode Q3
B is connected with the base stage B of the 4th triode Q4 other ends being connected afterwards with the 7th resistance R7, the collector C of the 3rd triode Q3 with
The other end of tenth resistance R10 is connected；The emitter E of 4th triode Q4 is connected with the emitter E of the 3rd triode Q3, and the 4th
There is fourth node, the collector of the 4th triode Q4 between the emitter E of triode Q4 and the emitter E of the 3rd triode Q3
C is grounded.Wherein, fourth node is connected as the output terminal of driving unit 40 with the control terminal G of switching tube 101.
A specific embodiment according to the present invention, the first triode Q1, the second triode Q2 and the 3rd triode Q3 can
For NPN type triode, the 4th triode Q4 can be PNP type triode.
Specifically, first control circuit 403 is connected the 3rd triode Q3 and the four or three jointly with second control circuit 404
The base stage of pole pipe Q4, to control the signal of the output terminal of push-pull circuit 402.When time of 20 output protection signal of current detecting unit
When number is not up to preset times threshold value, counter 401 exports low level to second control circuit 404, so that the first triode Q1
Shut-off, first control circuit 403 are switched on or off according to PPG control signals and by 402 controlling switch pipe 101 of push-pull circuit.
More specifically, when PPG control signals are high level, the second triode Q2 is open-minded, the 3rd triode Q3 shut-offs, the 4th triode
Q4 is open-minded, and driving unit 40 exports low level to the control terminal G of switching tube 101, so that switching tube 101 turns off；Believe when PPG is controlled
When number being low level, the second triode Q2 shut-offs, the 3rd triode Q3 is open-minded, the 4th triode Q4 shut-offs, and driving unit 40 is defeated
Go out high level to the control terminal G of switching tube 101, so that switching tube 101 is open-minded.In this way, driving unit 40 connects according to control signal
The PPG control signal controlling switches pipe 101 that receiving end 30 receives is switched on or off.
Further, when the number of 20 output protection signal such as rising edge signal of current detecting unit reaches preset times
During threshold value, counter 401 exports high level to second control circuit 404, so that the first triode Q1 is open-minded, the 3rd triode Q3
It is forced to be pulled low to low level with the base stage of the 4th triode Q4, driving unit 40 exports control of the low level to switching tube 101
G is held, so that switching tube 101 turns off, is frequently switched on or off so as to forbid switching tube 101 abnormal period occur, with protection switch
Pipe.
In this way, the protective device of the electromagnetic heating system of the embodiment of the present invention detected in real time by current detecting unit 20 it is humorous
The resonance current to shake in unit 10, and resonance current is handled, which is converted into digital signal, if humorous
The resonance current of unit 10 of shaking is more than predetermined current threshold, then current detecting unit 20 generates protection signal, driving unit 40
Counter 401 counts the number for receiving protection signal, if stored count number reaches preset times threshold value for example
10 times, then decision circuitry is in abnormality, and then second control circuit 404 exports low level driving switch pipe 101 and turns off, with
Protection switch pipe 101；If stored count number is not up to preset times threshold value such as 10 times, there is no different for decision circuitry
Often, second control circuit 404 exports high level, and then first control circuit 403 is received according to control signal receiving terminal 30
PPG control signals are switched on or off by 402 driving switch pipe 101 of push-pull circuit, so that electromagnetic heating system works normally.
To sum up, the protective device of the electromagnetic heating system proposed according to embodiments of the present invention, resonant element is in driving unit
Driving under carry out resonance heating, current detecting unit is detected the resonance current of resonant element, and big in resonance current
Protection signal is generated when predetermined current threshold, driving unit is not up to preset times threshold value in the number for receiving protection signal
When the PPG control signal driving switch pipes that are received according to control signal receiving terminal be switched on or off, and receiving protection letter
Number number driving switch pipe shut-off when reaching preset times threshold value.Thus, the guarantor of the electromagnetic heating system of the embodiment of the present invention
Protection unit driving switch pipe when the resonance current detected is abnormal turns off, electric caused by so as to avoid circuit abnormality
Flow control is out of control, is continually switched on or off when preventing switching tube from occurring abnormal, prevents inspection pot noise, reduces switching tube
Live load, protection switch pipe, lifts the reliability of product.
Fig. 3 is the block diagram of electromagnetic heating system according to embodiments of the present invention.As shown in figure 3, the electromagnetic heating
System 200 includes the protective device 100 of electromagnetic heating system.
To sum up, the electromagnetic heating system proposed according to embodiments of the present invention, by above-mentioned electromagnetic heating system, is detecting
Resonance current driving switch pipe shut-off when being abnormal, current control is out of control caused by so as to avoid circuit abnormality, prevents
Continually it is switched on or off when only switching tube occurs abnormal, prevents inspection pot noise, reduces the live load of switching tube, protection
Switching tube, lifts the reliability of product.
In the description of the present invention, it is to be understood that term " " center ", " longitudinal direction ", " transverse direction ", " length ", " width ",
" thickness ", " on ", " under ", "front", "rear", "left", "right", " vertical ", " level ", " top ", " bottom " " interior ", " outer ", " up time
The orientation or position relationship of the instruction such as pin ", " counterclockwise ", " axial direction ", " radial direction ", " circumferential direction " be based on orientation shown in the drawings or
Position relationship, is for only for ease of and describes the present invention and simplify description, rather than indicates or imply that signified device or element must
There must be specific orientation, with specific azimuth configuration and operation, therefore be not considered as limiting the invention.
In addition, term " first ", " second " are only used for description purpose, and it is not intended that instruction or hint relative importance
Or the implicit quantity for indicating indicated technical characteristic.Thus, define " first ", the feature of " second " can be expressed or
Implicitly include at least one this feature.In the description of the present invention, " multiple " are meant that at least two, such as two, three
It is a etc., unless otherwise specifically defined.
In the present invention, unless otherwise clearly defined and limited, term " installation ", " connected ", " connection ", " fixation " etc.
Term should be interpreted broadly, for example, it may be fixedly connected or be detachably connected, or integrally；Can be that machinery connects
Connect or be electrically connected；It can be directly connected, can also be indirectly connected by intermediary, can be in two elements
The connection in portion or the interaction relationship of two elements, unless otherwise restricted clearly.For those of ordinary skill in the art
For, the concrete meaning of above-mentioned term in the present invention can be understood as the case may be.
In the present invention, unless otherwise clearly defined and limited, fisrt feature can be with "above" or "below" second feature
It is that the first and second features directly contact, or the first and second features pass through intermediary mediate contact.Moreover, fisrt feature exists
Second feature " on ", " top " and " above " but fisrt feature are directly over second feature or oblique upper, or be merely representative of
Fisrt feature level height is higher than second feature.Fisrt feature second feature " under ", " lower section " and " below " can be
One feature is immediately below second feature or obliquely downward, or is merely representative of fisrt feature level height and is less than second feature.
In the description of this specification, reference term " one embodiment ", " some embodiments ", " example ", " specifically show
The description of example " or " some examples " etc. means specific features, structure, material or the spy for combining the embodiment or example description
Point is contained at least one embodiment of the present invention or example.In the present specification, schematic expression of the above terms is not
It must be directed to identical embodiment or example.Moreover, particular features, structures, materials, or characteristics described can be in office
Combined in an appropriate manner in one or more embodiments or example.In addition, without conflicting with each other, the skill of this area
Art personnel can be tied the different embodiments or example described in this specification and different embodiments or exemplary feature
Close and combine.
Although the embodiment of the present invention has been shown and described above, it is to be understood that above-described embodiment is example
Property, it is impossible to limitation of the present invention is interpreted as, those of ordinary skill in the art within the scope of the invention can be to above-mentioned
Embodiment is changed, changes, replacing and modification.
Claims (11)
- A kind of 1. protective device of electromagnetic heating system, it is characterised in that including：Resonant element, the resonant element include heating coil, resonant capacitance and switching tube；Current detecting unit, the input terminal of the current detecting unit are connected with the resonant element, the current detecting unit For being detected to the resonance current of the resonant element, and generate and protect when the resonance current is more than predetermined current threshold Protect signal；Control signal receiving terminal, the control signal receiving terminal are used to receive PPG control signals；Driving unit, the first input end of the driving unit are connected with the control signal receiving terminal, the driving unit Second input terminal is connected with the output terminal of the current detecting unit, the control of the output terminal of the driving unit and the switching tube End processed is connected, and the driving unit is used for when the number for receiving the protection signal is not up to preset times threshold value according to institute Stating PPG control signals drives the switching tube to be switched on or off, and reaches described pre- in the number for receiving the protection signal If the switching tube is driven to turn off during frequency threshold value.
- 2. the protective device of electromagnetic heating system according to claim 1, it is characterised in that the current detecting unit bag Include：Current sampling circuit, the current sampling circuit are connected with the resonant element, and the current sampling circuit is used to sample The resonance current of the resonant element；Current processing circuits, the current processing circuits are connected with the current sampling circuit, and the current processing circuits are used for The resonance current sampled is handled to generate current processing signal；Comparison circuit, the comparison circuit the second input terminal phase with the current processing circuits and the driving unit respectively Even, the comparison circuit is used to judge that the resonance current is more than the predetermined current threshold according to the current processing signal Protection signal described in Shi Shengcheng.
- 3. the protective device of electromagnetic heating system according to claim 2, it is characterised in that the current sampling circuit bag Sampling resistor is included, the sampling resistor is arranged in the resonant element, one end ground connection of the sampling resistor, the sampling electricity The other end of resistance is connected with the current processing circuits.
- 4. the protective device of electromagnetic heating system according to claim 2, it is characterised in that the current processing circuits bag Amplifying circuit is included, the amplifying circuit includes：First resistor, one end of the first resistor are connected with the current sampling circuit；Second resistance, one end of the second resistance are connected with the other end of the first resistor and have a first node；First operational amplifier, the positive input terminal of first operational amplifier are connected with the first node, first fortune The output terminal for calculating amplifier is connected with the other end of the second resistance and the comparison circuit respectively；3rd resistor, one end of the 3rd resistor are connected with the negative input end of first operational amplifier, the 3rd electricity The other end ground connection of resistance.
- 5. the protective device of electromagnetic heating system according to claim 4, it is characterised in that the current processing circuits are also Including isolation circuit, the isolation circuit is connected between the amplifying circuit and the current sampling circuit, the isolation electricity Road includes：4th resistance, one end of the 4th resistance are connected with the current sampling circuit；First capacitance, one end of first capacitance is connected with the other end of the 4th resistance and has section point, described The other end ground connection of first capacitance；Second operational amplifier, the negative input end of second operational amplifier are connected with the section point, second fortune The output terminal for calculating amplifier is connected with the positive input terminal of second operational amplifier and one end of the first resistor respectively.
- 6. the protective device of electromagnetic heating system according to claim 2, it is characterised in that the comparison circuit includes：3rd operational amplifier, the positive input terminal of the 3rd operational amplifier are connected with the current processing circuits, the 3rd fortune Calculate amplifier negative input end with provide reference voltage reference voltage offer circuit be connected, the 3rd operational amplifier it is defeated Outlet is connected with the second input terminal of the driving unit.
- 7. the protective device of electromagnetic heating system according to claim 1, it is characterised in that the driving unit includes：Counter, the counter are counted for docking received protection signal；Push-pull circuit, the output terminal of the push-pull circuit are connected with the control terminal of the switching tube；First control circuit, the input terminal of the first control circuit are connected with the control signal receiving terminal, first control The output terminal of circuit processed is connected with the input terminal of the push-pull circuit, and the first control circuit is used to be controlled according to the PPG Signal simultaneously controls the switching tube to be switched on or off by the push-pull circuit；Second control circuit, the input terminal of the second control circuit are connected with the counter, the second control circuit Output terminal is connected with the input terminal of the push-pull circuit, and the second control circuit is used to reach institute in the counting of the counter The switching tube is controlled to turn off by the push-pull circuit when stating preset times threshold value.
- 8. the protective device of electromagnetic heating system according to claim 7, it is characterised in that the second control circuit bag Include：5th resistance, one end of the 5th resistance are connected with the counter；6th resistance, one end of the 6th resistance are connected with the other end of the 5th resistance, the 6th resistance it is another End ground connection, has the 3rd node between the 6th resistance and the 5th resistance；7th resistance, one end of the 7th resistance are connected with default power supply；First triode, the base stage of first triode are connected with the 3rd node, the collector of first triode It is connected respectively with the other end of the 7th resistance and the input terminal of the push-pull circuit, the emitter of first triode connects Ground.
- 9. the protective device of electromagnetic heating system according to claim 8, it is characterised in that the first control circuit with The second control circuit shares the 7th resistance, and the first control circuit includes：8th resistance, one end of the 8th resistance are connected with the control signal receiving terminal；9th resistance, one end of the 9th resistance are connected with default power supply, the other end and the control of the 9th resistance Signal receiving end is connected；Second triode, the base stage of second triode are connected with the other end of the 8th resistance, second triode Collector be connected respectively with the other end of the 7th resistance and the input terminal of the push-pull circuit, second triode Emitter is grounded.
- 10. the protective device of electromagnetic heating system according to claim 7, it is characterised in that the preset times threshold value For 10, the counter is asynchronous decade counter.
- 11. a kind of electromagnetic heating system, it is characterised in that including the electromagnetic heating according to any one of claim 1-10 The protective device of system.
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| CN201610958445.XA CN108024405B (en) | 2016-11-03 | 2016-11-03 | Electromagnetic heating system and protection device thereof |
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|---|---|---|---|
| CN201610958445.XA CN108024405B (en) | 2016-11-03 | 2016-11-03 | Electromagnetic heating system and protection device thereof |
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| CN108024405B (en) | 2021-12-21 |
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