CN203870270U - Refrigerator electromagnetic door magnetic sensor - Google Patents
Refrigerator electromagnetic door magnetic sensor Download PDFInfo
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- CN203870270U CN203870270U CN201420278289.9U CN201420278289U CN203870270U CN 203870270 U CN203870270 U CN 203870270U CN 201420278289 U CN201420278289 U CN 201420278289U CN 203870270 U CN203870270 U CN 203870270U
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Abstract
The utility model discloses a refrigerator electromagnetic door magnetic sensor. In a circuit of the magnetic sensor, a detection resistor is connected in series with an inductor; the voltage at the two ends of a differential amplifier is added to the detection resistor to provide a signal equivalent to an induction current; when an induction H bridge is driven in two directions, a 2.5-Vbias voltage is added at the two ends of the differential amplifier, so that a ripple signal can be detected; then, the ripple of amplified signal is shielded through a high-pass filter, and the high-frequency noise is removed through a low-pass filter; the filtered signal is subjected to rectification and signal amplification through a non-inverting amplifier within the 0-5 V range; and a peak detector is utilized to set a DC voltage, of which the maximum ripple is smaller than 0.7 V. The DC output of the peak detector reflects the inductance coefficients directly, and can be easily sampled by a microprocessor to determine the state of the door. The main advantages of the magnetic sensor are that other components do not need to be added on the door, and the magnetic sensor is firm and reliable and low in cost.
Description
Technical field
The utility model relates to a kind of sensor, is specifically related to a kind of refrigerator electromagnetic door magnetic sensor.
Background technology
In daily life; people can run into such situation conventionally; shut again when opening after refrigerator doors; by the time rethink next time and open refrigerator doors; but it is very painstaking to find, this is because last refrigerator while opening, hot-air enter the variation that has caused refrigerator internal pressure; inside and outside refrigerator, form pressure differential, thereby made user be difficult for again opening the door.
Fisher & Paykel (F & P) company has proposed a solution at present, carrys out assisted user exactly open the door by electromagnetic system.Core in electromagnetic system is door controller, and the final requirement of door controller is the on off state that it can judge by door sensor refrigerator doors.The method of the current use of F & P is a special microswitch.Although this microswitch is very reliable, very expensive, in order to reduce costs, now need a kind of cheapness again reliably door sensor replace it.
Utility model content
In order to solve the above problems, the utility model aims to provide a kind of refrigerator electromagnetic door magnetic sensor, for replacing existing expensive microswitch.
For realizing above-mentioned technical purpose, reach above-mentioned technique effect, the utility model is achieved through the following technical solutions:
A kind of refrigerator electromagnetic door magnetic sensor, mainly comprise an inductive current ripple detection circuit, described inductive current ripple detection circuit comprises the first amplifier and the second amplifier, the reverse input end of described the first amplifier connects the first resistance, the input end in the same way of described the first amplifier is parallel with the second resistance and the 3rd resistance, the output terminal of described the first amplifier has the 5th resistance of the 4th resistance and ground connection by the first Capacitance parallel connection, between the reverse input end of described the first amplifier and output terminal, also cross-over connection has the 6th resistance; Described the first resistance connects Hi-pass filter, described the second electricity connects low-pass filter by an inductance, the reverse input end of described the first amplifier and in the same way between input end cross-over connection have the 7th, the 8th, the 9th resistance, described the 3rd resistance is by the second capacity earth, the two ends of described the second electric capacity are parallel with described the tenth resistance, and described the tenth resistance is by the 11 resistance eutral grounding;
The reverse input end of described the second amplifier connects the 12 resistance, the input end in the same way of described the second amplifier is parallel with described the 4th resistance and the 3rd electric capacity, described the 3rd capacity earth, the output terminal of described the second amplifier is by the 14 positive pole of resistance one general-purpose diode and the negative pole parallel connection of a voltage stabilizing diode, and between the reverse input end of described the first amplifier and output terminal, also cross-over connection has the 13 resistance; The plus earth of described voltage stabilizing diode, the negative pole of described general-purpose diode is parallel with the 4th electric capacity of the 16 resistance and ground connection by the 15 resistance.
A very little detection resistance and an inductance series connection.Differential amplifier both end voltage is added in to detect on resistance provides a signal that is equivalent to inductive current.When driving inductance H electric bridge in the time that both direction drives, the bias voltage of a 2.5V is added in the two ends of differential amplifier, make the ripple signal can be measured, then this signal being exaggerated masks ripple by a Hi-pass filter, removes high frequency noise by a low-pass filter.
Then this signal being filtered is carried out rectification and is amplified this signal by a noninverting amplifier in the scope of 0-5V.A peak detector is used to set the DC DC voltage of a maximum ripple lower than 0.7V.Therefore the DC of this peak detector output has directly reflected inductance coefficent, and can be determined easily the state of door by microprocessor samples.By setting input pin to the very short time of 0V, this peak detector can be reset.
Compared with prior art, the utlity model has following beneficial effect:
The utility model is the components and parts that need to not install any other on door additional in the major advantage of refrigerator electromagnetic door magnetic sensor, and than existing special microsensor cheapness time, it is possessing again suitable firm with it, the feature such as reliable.
Above-mentioned explanation is only the general introduction of technical solutions of the utility model, in order to better understand technological means of the present utility model, and can be implemented according to the content of instructions, below with preferred embodiment of the present utility model and coordinate accompanying drawing to be described in detail as follows.Embodiment of the present utility model is provided in detail by following examples and accompanying drawing thereof.
Brief description of the drawings
Accompanying drawing described herein is used to provide further understanding of the present utility model, forms the application's a part, and schematic description and description of the present utility model is used for explaining the utility model, does not form improper restriction of the present utility model.In the accompanying drawings:
Fig. 1 is circuit theory schematic diagram of the present utility model;
Fig. 2 is in the time that electromagnet is driven by repercussion, electromagnetic field distribution schematic diagram;
Fig. 3 is when with pwm signal drive magnetic, the ripple schematic diagram of electric current.
Embodiment
Below with reference to the accompanying drawings and in conjunction with the embodiments, describe the utility model in detail.
Shown in Figure 1, a kind of refrigerator electromagnetic door magnetic sensor, mainly comprise an inductive current ripple detection circuit, described inductive current ripple detection circuit comprises the first amplifier U1 and the second amplifier U2, the reverse input end of described the first amplifier U1 connects the first resistance R 1, the input end in the same way of described the first amplifier U1 is parallel with the second resistance R 2 and the 3rd resistance R 3, the output terminal of described the first amplifier U1 is parallel with the 5th resistance R 5 of the 4th resistance R 4 and ground connection by the first capacitor C 12, between the reverse input end of described the first amplifier U1 and output terminal, also cross-over connection has the 6th resistance R 6, described the first resistance R 1 connects Hi-pass filter LH, described the second resistance R 2 connects low-pass filter LP by an inductance L, the reverse input end of described the first amplifier U1 and in the same way between input end cross-over connection have the 7th, the 8th, the 9th resistance R 7, R8, R9, described the 3rd resistance R 3 is by the second capacitor C 2 ground connection, and the two ends of described the second capacitor C 2 are parallel with described the tenth resistance R 10, and described the tenth resistance R 10 is by the 11 resistance R 11 ground connection,
The reverse input end of described the second amplifier U2 connects the 12 resistance R 12, the input end in the same way of described the second amplifier U2 is parallel with described the 4th resistance R 4 and the 3rd capacitor C 3, described the 3rd capacitor C 3 ground connection, the output terminal of described the second amplifier U2 is by the positive pole of the 14 resistance R 14 1 general-purpose diode D1 and the negative pole parallel connection of a voltage stabilizing diode D2, and between the reverse input end of described the first amplifier U1 and output terminal, also cross-over connection has the 13 resistance R 13; The plus earth of described voltage stabilizing diode D2, the negative pole of described general-purpose diode D1 is parallel with the 4th capacitor C 4 of the 16 resistance R 16 and ground connection by the 15 resistance R 15.
Induction coefficient theory
Be arranged on the permanent magnet in refrigerator doors and be arranged on distance between the electromagnet of inside refrigerator door and inductance that refrigerator electromagnetic door magnetic sensor of the present utility model records has direct relation.According to Faraday's law, measured induction coefficient of electromagnet is that magnetic flux all directly and in electromagnetic circuit is proportional.When supposing the system is linear, this law is correct.If electromagnet opposite direction drives, inductance just reduces, and the just close electromagnet of permanent magnet, and this impact can be used to measure the state of door.
For the door that turns a refrigerator off, in the time driving inductance H electric bridge to be reversed driving, electromagnetic field distributes shown in Figure 2.In the time that alnico magnets are shifted to electromagnet, the interaction between magnetic field can change the total magnetic flux in circuit.Near magnetic flux magnet is because the negative function in magnetic field will reduce.Magnetic flux between electromagnet and alnico magnets is because the increase in the magnetic field that magnet produces will be risen.
Because be the strongest near the magnetic field at the two poles of the earth places, and the increase of electromagnet internal magnetic flux compares, and between magnet, the counteracting in magnetic field can cause its magnetic flux sharply to reduce pro rata.So final magnetic flux reduces.Thereby the inductance recording also reduces.
RL method time response
A method measuring electromagnet inductance is similar with measuring electric capacity.When on the resistance of making alive in an inductance and series connection, the rate of growth of electric current depends on inductance coefficent.Current rise to an one needed time of certain value can be measured, and also can measure the state of door.
The detection method of current ripples
In the time driving an electromagnet with a pwm signal, the ripple type that electric current shows is shown in Figure 3.The ripple of electric current and the inductance coefficent of coil and operating frequency have direct relation.The increase of inductance coefficent or frequency can cause very little current ripples, and vice versa.Select the PWM frequency of 250Hz to improve the amplitude of current ripples.
Circuit theory of the present utility model is shown in Figure 1, a very little detection resistance and an inductance series connection.Differential amplifier both end voltage is added in to detect on resistance provides a signal that is equivalent to inductive current.When H electric bridge is in the time that both direction drives, the bias voltage of a 2.5V is added in the two ends of differential amplifier, makes the ripple signal can be measured.Then this signal being exaggerated masks ripple by a Hi-pass filter, removes high frequency noise by a low-pass filter.
Then this signal being filtered is carried out rectification and is amplified this signal by a noninverting amplifier in the scope of 0-5V.A peak detector is used to set the DC DC voltage of a maximum ripple lower than 0.7V.Therefore the DC of this peak detector output has directly reflected inductance coefficent, and can be determined easily the state of door by microprocessor samples.By setting input pin to the very short time of 0V, this peak detector can be reset.
Being calculated as follows of the final components and parts numerical value of inductive current ripple detection circuit of the present utility model:
1, amplifier gain
The size of input voltage ripple--H electric bridge drives in the time of 40% duty-cycle--records about 60mV.The gain of design operation amplifier circuit reaches the final about 4V of output, and this is just in time in the scope of ADC input voltage.
Because ripple signal has been rectified, this effective input signal only has 30mV.Therefore the gain of differential amplifier and noninverting amplifier is:
；
Therefore the gain of differential amplifier elects 8 as, and the gain of noninverting amplifier is made as 16, and total gain is 128.
Correct differential operational amplifier must meet:
；
Therefore the gain of differential amplifier is:
；
R12 and R2 elect 100K as and ensure that with this differential amplifier has very high input impedance (200K).Two resistance must ensure that very greatly common mode current is very little.Obtain R3=R6=8 × 100 K Ω 820 K Ω from above formula.
The gain of noninverting amplifier is:
；
Therefore, for the gain 16 that obtains expecting, R13=820 K Ω and R12=56 K Ω.
2, voltage divider
When driving inductance H electric bridge in the time that both direction drives, differential amplifier needs a 2.5VDC bias voltage to survey ripple.This DC is got by the supply voltage of 15V:
；
；
；
；
Let?
?
。
3, wave filter
The angular frequency of Hi-pass filter is chosen in 25Hz.This is under being still retained when under PWM frequency, 101 decay and the main information of this signal are removing DC part.The formula of angular frequency is as follows:
；
Let?
。
The angular frequency of low-pass filter is chosen in 2.5KHz--more than 10 octaves of frequency-of-interest (10
1).The formula of low-pass filter is with the same above.R5 selects 68K to ensure can not be written into previous stage wave filter, therefore selects 10nF according to above formula C1.
4, Zener diode
Select the Zener diode of 5.1V to limit the output voltage of noninverting amplifier.By guaranteeing that voltage can not exceed 5.5V and come the ADC pin of shutter controller microprocessor.The resistance of a 10K is placed between the output terminal of operational amplifier and Zener diode and limits from operational amplifier maximum current out.
5, crest detector
Selecting 1N4148 diode to be used as crest detector uses.In the time selecting the value of crest detector capacitor C 4, must make compromise selects.Large electric capacity has stable voltage.But large electric capacity also can cause the input of crest detector to change slowly.The value of this capacitor C 4 is selected 15nF after consideration.
The maximum current of setting inflow C4 is 50mA,
。
The maximum input voltage of crest detector is exactly that the maximum output voltage of noninverting amplifier deducts the voltage on general-purpose diode D1.After crest detector is resetted again, the ADC pin of door controller microprocessor is just reset to 0V and electric current flows into pin from C4.Current settings is at 15mA, little more a lot of than maximum rated current 40mA;
。
The foregoing is only preferred embodiment of the present utility model, be not limited to the utility model, for a person skilled in the art, the utility model can have various modifications and variations.All within spirit of the present utility model and principle, any amendment of doing, be equal to replacement, improvement etc., within all should being included in protection domain of the present utility model.
Claims (1)
1. a refrigerator electromagnetic door magnetic sensor, it is characterized in that: mainly comprise an inductive current ripple detection circuit, described inductive current ripple detection circuit comprises the first amplifier (U1) and the second amplifier (U2), the reverse input end of described the first amplifier (U1) connects the first resistance (R1), the input end in the same way of described the first amplifier (U1) is parallel with the second resistance (R2) and the 3rd resistance (R3), the output terminal of described the first amplifier (U1) is parallel with the 5th resistance (R5) of the 4th resistance (R4) and ground connection by the first electric capacity (C1), between the reverse input end of described the first amplifier (U1) and output terminal, also cross-over connection has the 6th resistance (R6), described the first resistance (R1) connects Hi-pass filter (LH), described the second resistance (R2) connects low-pass filter (LP) by an inductance (L), the reverse input end of described the first amplifier (U1) and in the same way between input end cross-over connection have the 7th, the 8th, the 9th resistance (R7, R8, R9), described the 3rd resistance (R3) is by the second electric capacity (C2) ground connection, the two ends of described the second electric capacity (C2) are parallel with described the tenth resistance (R10), and described the tenth resistance (R10) is by the 11 resistance (R11) ground connection,
The reverse input end of described the second amplifier (U2) connects the 12 resistance (R12), the input end in the same way of described the second amplifier (U2) is parallel with described the 4th resistance (R4) and the 3rd electric capacity (C3), described the 3rd electric capacity (C3) ground connection, the output terminal of described the second amplifier (U2) is by the positive pole of the 14 resistance (R14) general-purpose diode (D1) and the negative pole parallel connection of a voltage stabilizing diode (D2), and between the reverse input end of described the first amplifier (U1) and output terminal, also cross-over connection has the 13 resistance (R13); The plus earth of described voltage stabilizing diode (D2), the negative pole of described general-purpose diode (D1) is parallel with the 4th electric capacity (C4) of the 16 resistance (R16) and ground connection by the 15 resistance (R15).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420278289.9U CN203870270U (en) | 2014-05-28 | 2014-05-28 | Refrigerator electromagnetic door magnetic sensor |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420278289.9U CN203870270U (en) | 2014-05-28 | 2014-05-28 | Refrigerator electromagnetic door magnetic sensor |
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| CN203870270U true CN203870270U (en) | 2014-10-08 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201420278289.9U Expired - Fee Related CN203870270U (en) | 2014-05-28 | 2014-05-28 | Refrigerator electromagnetic door magnetic sensor |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103984029A (en) * | 2014-05-28 | 2014-08-13 | 苏州工业职业技术学院 | Magnetic sensor of refrigerator electromagnetic door |
-
2014
- 2014-05-28 CN CN201420278289.9U patent/CN203870270U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103984029A (en) * | 2014-05-28 | 2014-08-13 | 苏州工业职业技术学院 | Magnetic sensor of refrigerator electromagnetic door |
| CN103984029B (en) * | 2014-05-28 | 2017-02-15 | 苏州工业职业技术学院 | Magnetic sensor of refrigerator electromagnetic door |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20141008 Termination date: 20150528 |
|
| EXPY | Termination of patent right or utility model |