CN108519571B - Method and device for offset correction of Hall current sensor of welding machine - Google Patents
Method and device for offset correction of Hall current sensor of welding machine Download PDFInfo
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- CN108519571B CN108519571B CN201810207616.4A CN201810207616A CN108519571B CN 108519571 B CN108519571 B CN 108519571B CN 201810207616 A CN201810207616 A CN 201810207616A CN 108519571 B CN108519571 B CN 108519571B
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- 238000012937 correction Methods 0.000 title claims abstract description 33
- 238000003466 welding Methods 0.000 title claims abstract description 22
- 238000000034 method Methods 0.000 title claims abstract description 14
- 238000005070 sampling Methods 0.000 claims description 23
- 239000003990 capacitor Substances 0.000 description 10
- 238000001514 detection method Methods 0.000 description 9
- 230000002411 adverse Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 230000005355 Hall effect Effects 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R35/00—Testing or calibrating of apparatus covered by the other groups of this subclass
Abstract
The invention discloses a Hall current sensor offset correction method for a welding machine, which comprises the following steps: step one, starting the welding machine, and detecting whether a Hall current sensor has current or not; step two, if the Hall current sensor has current, compensating a first offset value; if the Hall current sensor has no current, detecting the current of the Hall current sensor after a preset time; and thirdly, judging whether the current of the Hall current sensor is the same as a preset current, and if not, compensating a second offset value. The invention also discloses a device for correcting the offset of the Hall current sensor of the welding machine.
Description
Technical Field
The invention relates to the technical field of welding machines, in particular to a Hall current sensor offset correction method and device of a welding machine.
Background
The Hall current sensor converts primary large current into secondary micro voltage signals based on a magnetic balance Hall principle, and then a current value is obtained. According to the hall effect principle, a current I is supplied from the control current terminal of the hall element, and a magnetic field having a magnetic field strength B is applied in the normal direction of the plane of the hall element, so that an electric potential is generated in the direction perpendicular to the current and the magnetic field. The magnitude of the current flowing in the conductor can be measured indirectly by measuring the magnitude of the hall potential. Through the electric-magnetic-electric conversion, the sampling of the current insulation isolation is realized.
Hall current sensors have many advantages in industrial applications. The non-contact detection is adopted, so that the measurement of the current value can be directly realized without changing the original electric connection, the current value is isolated from the electric equipment, a plurality of unnecessary interferences are avoided, the electric equipment is not influenced, and the current waveform is fed back with high precision. The traditional detecting element is limited by a plurality of factors such as a specified frequency, a specified waveform, response lag and the like, is difficult to widely apply, the measuring range of a new-generation Hall current sensor is wide, the current of any waveform can be measured, the response speed is high, the transient peak current can be displayed in real time, the measuring precision is high, the measuring precision is better than 1%, the reliability is high, the average fault-free duration is long, the overload capacity is high, the measuring range is large, and the measuring range reaches ten thousand amperes.
The offset current is also called residual current or residual current, which means that no current flows in an actual wire, but the Hall sensor detects that current flows, so that feedback information is inconsistent with the actual current, and the electric equipment is in failure when the feedback information is light, and the personal safety is endangered when the feedback information is heavy.
The offset current is mainly caused by unstable operation of an operational amplifier in a Hall element or an electronic circuit, when the sensor is produced, the sensor is subjected to zero adjustment under the condition that the primary side current is zero at 25 ℃, but in practical application, different working environments cause the offset of the sensor to different degrees, and even the same electrical equipment cannot always work in the same environment. For safety and reliability reasons of the electrical system, in particular for personal safety reasons, offset correction of the hall current sensor is essential.
Disclosure of Invention
In view of the problems existing in the prior art, the invention provides a Hall current sensor offset correction method and device for a welding machine, which can automatically detect offset correction of a Hall sensor.
In order to achieve the above object, the present invention discloses a method for hall current sensor offset correction of a welder, comprising: step one, starting the welding machine, and detecting whether a Hall current sensor has current or not; step two, if the Hall current sensor has current, compensating a first offset value; if the Hall current sensor has no current, detecting the current of the Hall current sensor after a preset time; and thirdly, judging whether the current of the Hall current sensor is the same as a preset current, and if not, compensating a second offset value.
Further, the detecting whether the hall current sensor has a current in the first step specifically includes: sampling the Hall current sensor to obtain a sampling signal, and judging whether the Hall current sensor has current or not according to the sampling signal.
Further, the first offset value is a current value of the sampling signal.
Further, the second offset value is a difference between the current value of the hall current sensor and the preset current value.
Further, the preset time is two seconds after the welder stably works.
Furthermore, when the output current of the welding machine is constant and the output voltage fluctuation is within plus or minus 2 volts, the welding machine works stably.
The invention also discloses a Hall current sensor offset correction device for the welding machine, which comprises: a sampling signal, a preset signal, a first comparator unit and a second comparator unit; the sampling signal is connected with the negative input end of the first comparator unit, the preset signal is connected with the positive input end of the first comparator unit, and a first comparison circuit is formed with the output end of the first comparator unit; the sampling signal is connected with the positive input end of the second comparator unit, the preset signal is connected with the negative input end of the second comparator unit, and a second comparison circuit is formed by the sampling signal and the output end of the second comparator unit.
Further, when the sampling signal is greater than the preset signal, the output signal of the first comparison circuit is greater than zero, and the positive bias of the Hall current sensor is judged; when the sampling signal is smaller than or equal to the preset signal, the output signal of the second comparison circuit is larger than zero, and the negative bias of the Hall sensor is judged.
Furthermore, the first comparing circuit further comprises resistors R1, R2, R3, R6, capacitors C1, C2, and a zener diode ZD1, wherein one end of the resistor R1 is connected to the preset signal, the other end is connected to the positive input end of the first comparator unit and the negative input end of the second comparator unit, one end of the resistor R6 is connected to the positive input end of the resistor R1 and the comparator unit after being connected in parallel with the capacitor C1, the other end is grounded, one end of the capacitor C1 is connected to the other end of the power supply, one end of the resistor R2 is connected to the output end of the first comparator unit, the other end is connected to the resistor R3 and the zener diode ZD1, the other end of the resistor R3 is grounded, and the other end of the zener diode is used for outputting the output signal of the first comparing circuit.
Furthermore, the second comparing circuit further comprises resistors R4, R5, a capacitor C3, and a zener diode ZD2, wherein one end of the resistor R4 is connected with the sampling signal, the other end is connected with the negative input end of the first comparator unit and the positive input end of the second comparator unit, the resistor R5 and the capacitor C4 are connected in parallel, one face is connected with the resistor R4, the other end is grounded, one end of the resistor R7 is connected with the other end of the output end of the second comparator unit to be grounded, and one end of the zener diode ZD2 is connected with the other end of the output end of the second comparator unit to be used for outputting the output signal of the second comparing circuit.
Compared with the prior art, the offset correction of the sensor is realized by adopting a software and hardware regulation method, whether the offset occurs to the Hall current sensor is detected in real time through the detection circuit, and different parameter compensation is carried out according to the positive direction or the negative direction of the offset. The technical scheme can realize automatic correction, is convenient and reliable, saves time and labor and saves cost. The detection method and the detection circuit provided by the technical scheme can be suitable for different machine equipment and different Hall sensors, and adverse effects caused by current offset of the Hall current sensor are effectively avoided.
Drawings
The drawings are included to provide a better understanding of the invention and are not to be construed as unduly limiting the invention. Wherein:
FIG. 1 is a flow chart of a Hall current sensor offset correction method in accordance with the present invention;
fig. 2 is a schematic circuit diagram of the offset correction device for the hall current sensor according to the present invention.
Detailed Description
The presence of offset currents in hall current sensors as described in the background art can lead to inaccurate inspection of the actual operating device. When a hall current sensor is used in a welding machine, if forward offset occurs (that is, the sensor detects current under the condition of no current, so that the feedback current value is larger than the actual value, the offset even reaches ten amperes), many problems can occur in judging the current of the welding machine. If the current value is judged to be smaller than two amperes, the gas supply is stopped, and the minimum sampling current is larger than two amperes due to the larger sampling value, so that the welding machine supplies gas all the time; the arcing current is five amperes, and when the preset value is five amperes, the actual current is only zero amperes. The positive bias of the Hall causes that a plurality of functions cannot be realized, the use of the machine is seriously influenced, and even potential safety hazards exist. The negative bias and the positive bias of the Hall are opposite, and the current is actually available, but no current is detected, so that the detected current is smaller than the actual current. The negative bias of the Hall current has little influence on the functions of the welding machine, but after the actual current is large, when the welding machine works under high load for a long time, the service life of the welding machine is seriously influenced, and a machined workpiece is imperfect or even damaged.
The invention provides a Hall current sensor offset correction method and a Hall current sensor offset correction device for a welding machine, which can automatically detect offset correction of a Hall sensor, can effectively detect whether offset current exists in the Hall current sensor, and can compensate offset values when the welding machine works.
To make the objects, advantages and features of the present invention more apparent, the apparatus of the present invention will be described in further detail with reference to fig. 1 and 2. It should be noted that the drawings are in a very simplified form and are all to a non-precise scale, merely for convenience and clarity in aiding in the description of embodiments of the invention.
As used in this specification, the singular forms "a", "an" and "the" include plural referents unless the content clearly dictates otherwise. As used in this specification, the term "or" is generally employed in its sense including "and/or" unless the content clearly dictates otherwise.
Fig. 1 is a flowchart of a hall current sensor offset correction method according to the present invention. As shown in fig. 1, the flowchart includes a power-on self-test S1. The welding machine is in a non-working state after being started, at the moment, the output current of the Hall current sensor is zero, and at the moment, the current value fed back by the sensor is zero. The current value S2 fed back by the sensor is detected. The Hall current sensor is connected with a detection circuit, the detection circuit adopts the output current S3 of the Hall current sensor, and if the output current of the Hall current sensor is zero at this time, no current flows through the Hall current sensor and no offset current exists. The welder is operating normally and starts to enter an operating state S5. If the output current of the Hall current sensor is not zero at the moment, the positive offset of the Hall current sensor occurs. To reduce the error, the offset of the welder at two seconds on is recorded. Correction is performed in the current calculation in the program, and the actual current is reduced due to the forward bias of the sensor, and the offset S4 is increased in the current calculation. In order to prevent the fluctuation of current sampling, the offset value fed back by the sensor is selected as a correction parameter when the power is turned on for two seconds, the correction parameter is not modified, and the correction parameter is reselected when the power is turned on next time.
After the welder enters the working state, the output current is constant, the output voltage fluctuation is within the allowable range, such as positive and negative 2V, and the welder can be regarded as a stable working state S5 at the moment. After the welder enters a stable working state for a certain time, for example, after two seconds, the current value of the Hall current sensor is not changed any more S6. At this time, the magnitude S7 of the current preset value and the current value fed back by the sensor is compared. If the two values are the same, the Hall current sensor works normally S8, otherwise, negative bias occurs, the preset value is larger than the feedback value, and the difference between the two values is taken as the correction parameter S9. The output actual current is larger at this time, so the correction parameter is subtracted from the current calculation to obtain the actual current. The fluctuation is also prevented, the correction parameters are only taken once and are not modified, and the correction parameters are selected again when the computer is started next time.
Fig. 2 is a schematic circuit diagram of the offset correction device for the hall current sensor according to the present invention. The hardware circuit is designed to judge the Hall offset condition, sample the signal IF, preset the signal IG and compare the two signals. When the IF is larger than the IG, namely the Atest signal is larger than zero, the Hall positive bias is judged, the offset value is IF, and when the IF is smaller than or equal to the IG, namely the Btust signal is larger than zero, the Hall negative bias is judged, and the offset value is IG-IF. Otherwise, the Hall is normal. As shown in fig. 2, the hardware circuit mainly includes a first comparator unit U1 and a second comparator unit U2. The sampling signal IF is connected to the negative input end of the first comparator unit U1, the preset signal IG is connected to the positive input end of the first comparator unit U1, and a first comparison circuit is formed with the output end of the first comparator unit U1. The sampling signal is connected with the positive input end of the second comparator unit U2, the preset signal is connected with the negative input end of the second comparator unit U2, and a second comparison circuit is formed by the sampling signal and the output end of the second comparator unit U2. When the hardware circuit detects positive bias, the Hall current detector inputs a correction parameter of +IF. When the hardware circuit detects a negative bias, the hall current detector inputs a correction parameter of- (IG-IF).
The first comparison circuit further comprises resistors R1, R2, R3 and R6, capacitors C1 and C2 and a zener diode ZD1, one end of the resistor R1 is connected with the preset signal, the other end of the resistor R1 is connected with the positive input end of the first comparator unit and the negative input end of the second comparator unit, one end of the resistor R6 is connected with the positive input end of the resistor R1 and the comparator unit after being connected with the capacitor C1 in parallel, the other end of the resistor R6 is grounded, one end of the capacitor C1 is connected with the other end of the power supply and grounded, one end of the resistor R2 is connected with the output end of the first comparator unit, the other end of the resistor R3 is connected with the zener diode ZD1, and the other end of the resistor R3 is grounded, and the other end of the zener diode is used for outputting the output signal of the first comparison circuit.
The second comparison circuit further comprises resistors R4, R5 and R5, a capacitor C3 and a zener diode ZD2, wherein one end of the resistor R4 is connected with the sampling signal, the other end of the resistor R4 is connected with the negative input end of the first comparator unit and the positive input end of the second comparator unit, one face of the resistor R5 and the capacitor C4 are connected in parallel, the other end of the resistor R5 is grounded, one end of the resistor R7 is connected with the other end of the output end of the second comparator unit and grounded, and one end of the zener diode ZD2 is connected with the other end of the output end of the second comparator unit and is used for outputting the output signal of the second comparison circuit.
Compared with the prior art, the offset correction of the sensor is realized by adopting a software and hardware regulation method, whether the offset occurs to the Hall current sensor is detected in real time through the detection circuit, and different parameter compensation is carried out according to the positive direction or the negative direction of the offset. The technical scheme can realize automatic correction, is convenient and reliable, saves time and labor and saves cost. The detection method and the detection circuit provided by the technical scheme can be suitable for different machine equipment and different Hall sensors, and adverse effects caused by current offset of the Hall current sensor are effectively avoided.
The above description is only illustrative of the preferred embodiments of the present invention and is not intended to limit the scope of the present invention, and any alterations and modifications made by those skilled in the art based on the above disclosure shall fall within the scope of the appended claims.
Claims (3)
1. A method for hall current sensor offset correction for a welder, comprising:
step one, starting the welding machine, and detecting whether a Hall current sensor has current or not;
step two, if the Hall current sensor has current, compensating a first offset value; if the Hall current sensor has no current, detecting the current of the Hall current sensor after a preset time;
judging whether the current of the Hall current sensor is the same as a preset current or not, and if not, compensating a second offset value;
the detecting whether the hall current sensor has current specifically includes: sampling the Hall current sensor to obtain a sampling signal, and judging whether the Hall current sensor has current according to the sampling signal;
the first offset value is a current value of the sampling signal;
the second offset value is the difference between the current value of the Hall current sensor and the preset current value.
2. The method of hall current sensor offset correction of claim 1, wherein the preset time is two seconds after steady operation of the welder.
3. The method of hall current sensor offset correction of claim 2 wherein when the welder output current is constant, the output voltage fluctuates to within plus or minus 2 volts, which is a steady operation.
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| CN201810207616.4A CN108519571B (en) | 2018-03-14 | 2018-03-14 | Method and device for offset correction of Hall current sensor of welding machine |
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| CN201810207616.4A CN108519571B (en) | 2018-03-14 | 2018-03-14 | Method and device for offset correction of Hall current sensor of welding machine |
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| CN108519571B true CN108519571B (en) | 2024-01-23 |
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| CN109459715B (en) * | 2018-10-17 | 2021-03-26 | 宁波中车时代传感技术有限公司 | Closed-loop Hall effect current sensor simulation method |
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