CN102298406A - Electric heater and control device thereof - Google Patents
Electric heater and control device thereof Download PDFInfo
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- CN102298406A CN102298406A CN201110248145XA CN201110248145A CN102298406A CN 102298406 A CN102298406 A CN 102298406A CN 201110248145X A CN201110248145X A CN 201110248145XA CN 201110248145 A CN201110248145 A CN 201110248145A CN 102298406 A CN102298406 A CN 102298406A
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Abstract
The invention discloses an electric heater and a control device thereof. The electric heater comprises a heating circuit which is provided with a positive or negative resistance temperature coefficient characteristic, and a control device which further comprises a current detection circuit and a heating control circuit, wherein the current detection circuit is used for detecting the present current value of the heating circuit when the heating circuit works; and the heating control circuit is used for controlling the heating circuit to work according to the present current value of the heating circuit. Therefore, the electric heater disclosed by the invention can use the resistance characteristic of the electric heater to realize heating control, so as to ensure that the electric heater can work normally.
Description
Technical field
The present invention relates to electric heater, relate in particular to a kind of electric heater and control device thereof that adds heat control based on current detecting.
Background technology
Conventional electric heater mainly adopts the mode of aiding sensors, such as thermistor, mechanical type temperature switch etc., comes parameters such as detecting sensor resistance or temperature, and then heating line is added heat control.Be subject to the factor such as sensitivity, life-span, reaction time, failure rate of sensor, the situation of control fails often occurs, cause the well heater cisco unity malfunction.
In addition, the characteristics of existing thick film electric heater heat up rapidly, according to the difference of power density, can reach the temperature of several Baidu in several seconds; The speed that heats up far surpasses the response time of moment sensor, thus the thick film electric heater Yin Wendu often to occur too high, burn out the situation of circuit.
In summary, existing electric heater obviously exists inconvenience and defective on reality is used, so be necessary to be improved.
Summary of the invention
At above-mentioned defective, the object of the present invention is to provide a kind of electric heater and control device thereof, it can utilize the resistance characteristic of self to realize adding heat control, to guarantee the electric heater operate as normal.
To achieve these goals, the invention provides a kind of electric heater, include:
Heater circuit has plus or minus temperature-coefficient of electrical resistance characteristic;
Control device further comprises current detection circuit and heating control circuit:
Described current detection circuit is used for detecting the current current value of described heater circuit when described heater circuit is worked;
Described heating control circuit is used for the current current value according to described heater circuit, controls described heater circuit work.
According to electric heater of the present invention, described heater circuit has the positive temperature coefficient characteristic; When the current current value that detects described heater circuit when described current detection circuit was lower than first reservation threshold, described heating control circuit disconnected the power supply that is applied to described heater circuit.
According to electric heater of the present invention, described heater circuit has the negative temperature coefficient of resistance characteristic; When the current current value that detects described heater circuit when described current detection circuit was higher than second reservation threshold, described heating control circuit disconnected the power supply that is applied to described heater circuit.
According to electric heater of the present invention, described heater circuit has the positive temperature coefficient characteristic; When the current current value that detects described heater circuit when described current detection circuit was lower than at least one reservation threshold, described heating control circuit reduced the power output of described heater circuit.
According to electric heater of the present invention, described heater circuit has the negative temperature coefficient of resistance characteristic; When the current current value that detects described heater circuit when described current detection circuit was higher than at least one reservation threshold, described heating control circuit reduced the power output of described heater circuit.
According to electric heater of the present invention, described electric heater is a thick film heater.
According to electric heater of the present invention, described current detection circuit adopts detection current resistor to add operational amplifier, current transformer, voltage transformer (VT), modular type Hall current sensor or isolated amplifier, detects the current current value of described heater circuit.
According to electric heater of the present invention, described control device also comprises:
On-off element is used to disconnect or the closed power supply that is applied to described heater circuit;
Delay circuit is used for starting the delay circuit timing when the power supply that is applied to described heater circuit disconnects, and described delay circuit picks up counting behind predetermined amount of time, controls described on-off element closure.
According to electric heater of the present invention, described on-off element adopts electromagnetic relay or bidirectional triode thyristor.
The present invention also provides a kind of control device that is applied to described electric heater, and the heater circuit of described electric heater has plus or minus temperature-coefficient of electrical resistance characteristic, and described control device comprises:
Described current detection circuit is used for detecting the current current value of described heater circuit when described heater circuit is worked;
Described heating control circuit is used for the current current value according to described heater circuit, controls described heater circuit work.
The present invention does not need additional sensor, but utilize the plus or minus temperature-coefficient of electrical resistance characteristic of heater circuit self, the current value that detects heater circuit by current detection circuit changes, change the work control that realizes heater circuit according to described current value by heating control circuit again, described work control is preferably the power supply that disconnection, closure are applied to heater circuit, perhaps control the power output of electric heater, thus reach electric heater constant temperature, prevent the effect that dry combustion method damages.With respect to the control mode of existing aiding sensors, clear superiority such as that the heating controlling schemes of electric heater of the present invention has is highly sensitive, the life-span long, the reflection time is short, failure rate is low, thus can guarantee the electric heater operate as normal to greatest extent.
Description of drawings
Fig. 1 is the structural representation of electric heater of the present invention;
Fig. 2 is the structural representation of the preferred thick film electric heater of the present invention;
Fig. 3 is the synoptic diagram of the current detection circuit of control device in the first embodiment of the invention;
Fig. 4 is the structural representation of the control device of electric heater in the second embodiment of the invention;
Fig. 5 A is the graph of relation of the temperature and the resistance value of electric heater in the third embodiment of the invention;
Fig. 5 B is the temperature of electric heater in the third embodiment of the invention and the graph of relation of current value;
Fig. 5 C is insulation (time-delay) duty curve map in the third embodiment of the invention.
Embodiment
In order to make purpose of the present invention, technical scheme and advantage clearer,, the present invention is further elaborated below in conjunction with drawings and Examples.Should be appreciated that specific embodiment described herein only in order to explanation the present invention, and be not used in qualification the present invention.
Fig. 1 shows the structure of electric heater of the present invention, and described electric heater 100 mainly includes control device 10 and heater circuit 20, wherein:
Described control device 10 is connected in the whole working line of electric heater 100 with heater circuit 20, and electric heater 100 of the present invention can be applicable to multiple occasions such as liquid, gas, convective heating, radiation heating.And electric heater 100 of the present invention also can work together in conjunction with traditional sensors, can reach better effect.
Fig. 2 is the structural representation of the preferred thick film electric heater of the present invention, and described thick film electric heater 100 also comprises the substrate 30, the electrode ejector 40 that are used to carry heater circuit 20 except comprising control device 10 and heater circuit 20.In the present embodiment substrate 30 be shaped as disc, substrate 30 also can be different shapes such as square, polygon, tubulose certainly.The substrate 30 of thick film electric heater 100 can be that materials such as stainless steel, pottery, devitrified glass are made, and stainless steel substrate increases insulation course therein above the substrate, and heater circuit 20 is laid in above the insulation course.The control device 10 of this thick film electric heater 100 adopts little power consumption high precision IC (Integrated Circuit, integrated circuit) control, and very burst pulse power supply is adopted in the IC power supply, and it is little to have a standby current, characteristics such as little power consumption.Through test of many times, this thick film electric heater 100 is specially adapted to the fluid heating; When heating, produce local temperature protection too high, local dry burning and compare, have remarkable advantages with the traditional protection device for fluid.And response speed of the present invention is fast, reach the parameter of setting at heat-generating disc after, open-circuit line immediately, the corresponding time is less than several milliseconds (ms).
Fig. 3 is the synoptic diagram of the current detection circuit of control device in the first embodiment of the invention, the described current detection circuit 11 preferred combinations that detect current resistor Rsense and operational amplifier A MP that adopt, this electric current electrical measurement circuit 11 has the advantage that cost is low, precision is higher, volume is little.Certainly, current detection circuit 11 can also adopt other schemes, for example adopt current transformer, voltage transformer (VT), modular type Hall current sensor (as the Allegro current sensor) or isolated amplifier (as the light-coupled isolation amplifier of AVAGO, the condenser type isolated amplifier of TI, the sigma delta formula isolated amplifier of ADI etc.), detect the current current value of heater circuit 20, repeat no more herein.
Fig. 4 is the structural representation of the control device of electric heater in the second embodiment of the invention, and described control device 10 comprises current detection circuit 11, heating control circuit 12, on-off element 13 and delay circuit 14, wherein:
On-off element 13 is used to disconnect or the closed power supply 200 that is applied to heater circuit 20.
The on-off element 13 preferred electromagnetic relays that adopt, because relay often have open, normally closed contact, at control device 10 built-in time-delay switch control circuits, the normally opened contact of relay is communicated with delay circuit 14, when electric heater 100 disconnects heating, normally opened contact and delay circuit 14 are connected, pick up counting, after the time of delay requirement, the delay switch action, make the electromagnetic relay adhesive, electric heater 100 is started working; Electric heater 100 can disconnect circularly, heat within the temperature range that requires; Reach maintenance temperature unanimity, play the purpose of constant temperature.
Start delay circuit 14 and on-off element 13, also can adopt single-chip microcomputer or software to control.
Certainly, the present invention not necessarily adopts delay switch circuit, also can adopt other mode, such as the methods such as power that reduce heater circuit 20.
In third embodiment of the invention, heater circuit 20 has the positive temperature coefficient characteristic; The current current value that detects heater circuit 20 when current detection circuit 11 is lower than first reservation threshold, and (predetermined value is a) time, and heating control circuit 12 disconnects the power supply 200 that is applied to heater circuit 20.When having electric heater 100 operate as normal of positive temperature coefficient, it is big that the resistance value of heater circuit 20 can become along with the rising of temperature, according to Ohm law, current value on heater circuit 20 can diminish, when the current value that detects heater circuit 20 when control device 10 is lower than predetermined value a, control device 10 switch inside elements 13 disconnect the power supply 200 of heater circuit 20, and at this moment electric heater 100 quits work.
When preventing the occasion that electric heater 100 dry combustion methods damage, liquid electric heater for example; Suppose that the required electric current of electric heater 100 operate as normal is c, the current value c the when value of predetermined value a is lower than electric heater 100 operate as normal, promptly during c＞a, the electric heater 100 of this moment under normal circumstances all is in normal duty.When liquid partly dryouies or liquid when absolutely dry, electric heater 100 is in improper situation, and the current value of this moment descends because of resistance value raises, when reaching predetermined value a, control device 10 disconnects heater circuit 20, and electric heater 100 quits work, and has prevented that electric heater 100 from damaging because of temperature is too high.
For example, one thick film electric heater, the resistance value of normal temperature heater circuit 20 (T1=25 ℃) is R1=20 Ω, heater circuit 20 TCR=1500PPM, according to Ohm law, when adopting the alternating current of 220VAC, corresponding initial current is: 11A, suppose that electric heater 100 serviceability temperatures are that the T2=350 ℃ of resistance value when the electric heater operate as normal is: R2=29.75 Ω, the corresponding work electric current is: 7.395A;
After electric heater 100 energisings, electric heater 100 is started working, and the temperature of heater circuit 20 raises gradually, and after a period of time, temperature reaches 350 ℃, and this moment, the resistance value of heater circuit 20 reached 29.75 Ω; Electric current in the heater circuit 20 reduces near predetermined value 7.38A at this moment, and temperature continues to raise, and electric current continues to diminish, and when reaching predetermined value 7.38A, disconnects the power supply 200 of heater circuit 20 immediately, and electric heater 100 quits work, shown in Fig. 5 A and Fig. 5 B.
The power of also available electric heater 100 and time are represented the work of electric heater and stop, the operating voltage of electric heater 100 is example with 220VAC, heater circuit 20 is warmed up to 350 ℃ of time t1 from 25 ℃ of normal temperature, electric heater 20 is t2 from delay time (quitting work cut-in time), shown in Fig. 5 C.
In fourth embodiment of the invention, heater circuit 20 has the negative temperature coefficient of resistance characteristic.When the current current value that detects heater circuit 20 when current detection circuit 11 was higher than second reservation threshold (predetermined value b), heating control circuit 12 disconnected the power supply 200 that is applied to heater circuit 20.When having electric heater 100 operate as normal of negative temperature coefficient of resistance, the resistance value of heater circuit 20 can diminish along with the rising of temperature, according to Ohm law, it is big that current value on heater circuit 20 can become, when the current value that detects heater circuit 20 when control device 10 is higher than predetermined value b, control device 10 switch inside elements 13 disconnect the power supply 200 of heater circuit 20, and electric heater 100 quits work.
When preventing the occasion that electric heater 100 dry combustion methods damage, liquid electric heater for example; Suppose that the required electric current of electric heater operate as normal is c, the current value c the when value of predetermined value b is higher than electric heater 100 operate as normal, promptly during b＞c, the electric heater 100 of this moment under normal circumstances all is in normal duty.When liquid partly dryouies or liquid when absolutely dry, electric heater 100 is in improper situation, and the electric current of this moment increases because of resistance reduces, when reaching predetermined value b, control device 10 disconnects electric heater 100 circuits, and electric heater 100 quits work, and has prevented that electric heater 100 from damaging because of temperature is too high.
In fifth embodiment of the invention, heater circuit 20 has the positive temperature coefficient characteristic; When the current current value that detects heater circuit 20 when current detection circuit 11 was lower than at least one reservation threshold, heating control circuit 12 reduced the power output of heater circuits 20, reaches the temperature of expection up to electric heater 100.
In sixth embodiment of the invention, heater circuit 20 has the negative temperature coefficient of resistance characteristic; When the current current value that detects heater circuit 20 when current detection circuit 11 was higher than at least one reservation threshold, heating control circuit 12 reduced the power output of heater circuits 20, reaches the temperature of expection up to electric heater 100.
In sum, the present invention does not need additional sensor, but utilize the plus or minus temperature-coefficient of electrical resistance characteristic of heater circuit self, the current value that detects heater circuit by current detection circuit changes, change the work control that realizes heater circuit according to described current value by heating control circuit again, described work control is preferably the power supply that disconnection, closure are applied to heater circuit, perhaps control the power output of electric heater, thus reach electric heater constant temperature, prevent the effect that dry combustion method damages.With respect to the control mode of existing aiding sensors, clear superiority such as that the heating controlling schemes of electric heater of the present invention has is highly sensitive, the life-span long, the reflection time is short, failure rate is low, thus can guarantee the electric heater operate as normal to greatest extent.
Certainly; the present invention also can have other various embodiments; under the situation that does not deviate from spirit of the present invention and essence thereof; those of ordinary skill in the art work as can make various corresponding changes and distortion according to the present invention, but these corresponding changes and distortion all should belong to the protection domain of the appended claim of the present invention.
Claims (10)
1. an electric heater is characterized in that, includes:
Heater circuit has plus or minus temperature-coefficient of electrical resistance characteristic;
Control device further comprises current detection circuit and heating control circuit:
Described current detection circuit is used for detecting the current current value of described heater circuit when described heater circuit is worked;
Described heating control circuit is used for the current current value according to described heater circuit, controls described heater circuit work.
2. electric heater according to claim 1 is characterized in that described heater circuit has the positive temperature coefficient characteristic; When the current current value that detects described heater circuit when described current detection circuit was lower than first reservation threshold, described heating control circuit disconnected the power supply that is applied to described heater circuit.
3. electric heater according to claim 1 is characterized in that described heater circuit has the negative temperature coefficient of resistance characteristic; When the current current value that detects described heater circuit when described current detection circuit was higher than second reservation threshold, described heating control circuit disconnected the power supply that is applied to described heater circuit.
4. electric heater according to claim 1 is characterized in that described heater circuit has the positive temperature coefficient characteristic; When the current current value that detects described heater circuit when described current detection circuit was lower than at least one reservation threshold, described heating control circuit reduced the power output of described heater circuit.
5. electric heater according to claim 1 is characterized in that described heater circuit has the negative temperature coefficient of resistance characteristic; When the current current value that detects described heater circuit when described current detection circuit was higher than at least one reservation threshold, described heating control circuit reduced the power output of described heater circuit.
6. electric heater according to claim 1 is characterized in that, described electric heater is a thick film heater.
7. electric heater according to claim 1, it is characterized in that, described current detection circuit adopts detection current resistor to add operational amplifier, current transformer, voltage transformer (VT), modular type Hall current sensor or isolated amplifier, detects the current current value of described heater circuit.
8. electric heater according to claim 1 is characterized in that, described control device also comprises:
On-off element is used to disconnect or the closed power supply that is applied to described heater circuit;
Delay circuit is used for starting described delay circuit and picking up counting when the power supply that is applied to described heater circuit disconnects, and described delay circuit picks up counting behind predetermined amount of time, controls described on-off element closure.
9. electric heater according to claim 8 is characterized in that, described on-off element adopts electromagnetic relay or bidirectional triode thyristor.
10. control device that is applied to as claim 1～9 electric heater as described in each, the heater circuit of described electric heater has plus or minus temperature-coefficient of electrical resistance characteristic, it is characterized in that, and described control device comprises:
Described current detection circuit is used for detecting the current current value of described heater circuit when described heater circuit is worked;
Described heating control circuit is used for the current current value according to described heater circuit, controls described heater circuit work.
Priority Applications (1)
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| CN201110248145XA CN102298406A (en) | 2011-08-24 | 2011-08-24 | Electric heater and control device thereof |
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| CN201110248145XA CN102298406A (en) | 2011-08-24 | 2011-08-24 | Electric heater and control device thereof |
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Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103383103A (en) * | 2013-08-01 | 2013-11-06 | 苏州华瑞能泰发电技术有限公司 | Steam generation device |
| CN103807915A (en) * | 2014-02-25 | 2014-05-21 | 马斌 | Safety heater for college students |
| CN104038221A (en) * | 2013-03-07 | 2014-09-10 | 美的集团股份有限公司 | Electric heater and method for carrying out fault identification on AD input device of electric heater |
| CN104793094A (en) * | 2014-01-22 | 2015-07-22 | 珠海格力电器股份有限公司 | Detection circuit and method for electric heater and electric heating system |
| CN105190270A (en) * | 2013-03-14 | 2015-12-23 | Zf腓德烈斯哈芬股份公司 | Arrangement for testing a device for protecting an electronic component against overheating and pertaining method |
| CN106642720A (en) * | 2016-11-17 | 2017-05-10 | 佛山市云米电器科技有限公司 | Pre-induction type anti-dry burning structure of rapid water heating device |
| CN110857796A (en) * | 2018-08-24 | 2020-03-03 | 广东松下环境系统有限公司 | Heating ventilator and control method thereof |
| CN111343736A (en) * | 2020-03-12 | 2020-06-26 | 胡艳军 | Immersion type thick film liquid heater and electronic dry burning prevention method thereof |
| CN111668803A (en) * | 2020-06-05 | 2020-09-15 | 凤凰光学股份有限公司 | Three-level safety protection circuit of heating system |
| CN113483407A (en) * | 2021-05-26 | 2021-10-08 | 海信（山东）空调有限公司 | Control method, device and system of PTC electric heater and air conditioner |
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Cited By (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104038221B (en) * | 2013-03-07 | 2017-04-19 | 美的集团股份有限公司 | Electric heater and method for carrying out fault identification on AD input device of electric heater |
| CN104038221A (en) * | 2013-03-07 | 2014-09-10 | 美的集团股份有限公司 | Electric heater and method for carrying out fault identification on AD input device of electric heater |
| CN105190270A (en) * | 2013-03-14 | 2015-12-23 | Zf腓德烈斯哈芬股份公司 | Arrangement for testing a device for protecting an electronic component against overheating and pertaining method |
| CN103383103A (en) * | 2013-08-01 | 2013-11-06 | 苏州华瑞能泰发电技术有限公司 | Steam generation device |
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| CN104793094B (en) * | 2014-01-22 | 2018-05-18 | 珠海格力电器股份有限公司 | Detection circuit and method for electric heater and electric heating system |
| CN103807915A (en) * | 2014-02-25 | 2014-05-21 | 马斌 | Safety heater for college students |
| CN106642720A (en) * | 2016-11-17 | 2017-05-10 | 佛山市云米电器科技有限公司 | Pre-induction type anti-dry burning structure of rapid water heating device |
| CN110857796A (en) * | 2018-08-24 | 2020-03-03 | 广东松下环境系统有限公司 | Heating ventilator and control method thereof |
| CN110857796B (en) * | 2018-08-24 | 2022-08-12 | 广东松下环境系统有限公司 | Heating ventilator and control method thereof |
| CN111343736A (en) * | 2020-03-12 | 2020-06-26 | 胡艳军 | Immersion type thick film liquid heater and electronic dry burning prevention method thereof |
| CN111668803A (en) * | 2020-06-05 | 2020-09-15 | 凤凰光学股份有限公司 | Three-level safety protection circuit of heating system |
| CN111668803B (en) * | 2020-06-05 | 2022-08-09 | 杭州凤凰智能控制有限公司 | Three-level safety protection circuit of heating system |
| CN113483407A (en) * | 2021-05-26 | 2021-10-08 | 海信（山东）空调有限公司 | Control method, device and system of PTC electric heater and air conditioner |
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Application publication date: 20111228 |