CN113099566B - Electromagnetic heating control chip - Google Patents
Electromagnetic heating control chip Download PDFInfo
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- CN113099566B CN113099566B CN202110410824.6A CN202110410824A CN113099566B CN 113099566 B CN113099566 B CN 113099566B CN 202110410824 A CN202110410824 A CN 202110410824A CN 113099566 B CN113099566 B CN 113099566B
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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
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/64—Heating using microwaves
- H05B6/66—Circuits
- H05B6/68—Circuits for monitoring or control
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Abstract
The invention provides an electromagnetic heating control chip, the control chip includes: the device comprises a controller, a pulse width generator, an analog-to-digital conversion module, a linear voltage stabilizer and a current detection module; the current detection module comprises a differential amplifier, a first comparator, a first resistor and a second resistor, is used for acquiring and amplifying voltages at two ends of an external sampling resistor to obtain a first sampling voltage, and is also used for detecting the current surge; the analog-to-digital conversion module is used for performing analog-to-digital conversion on the first sampling voltage and inputting the first sampling voltage into the controller, so that the controller obtains sampling current according to the first sampling voltage after the analog-to-digital conversion; the pulse width generator is used for controlling the working state of the external driving circuit according to the current surge state; the problems that an electromagnetic heating control chip in the prior art is inaccurate in current sampling, not sensitive in current surge response and the like are solved, the accuracy of current detection and the surge response speed are improved, and therefore the stability of an IGBT protection mechanism in an electromagnetic heating product is improved.
Description
Technical Field
The invention relates to the technical field of electronics, in particular to an electromagnetic heating control chip.
Background
At present, electromagnetic heating products such as induction cookers and IH pots are more and more popular, and an electromagnetic heating control chip with high performance, high integration and rich IGBT automatic protection mechanism becomes a key factor of the reliability of the products such as the induction cookers IH pots; however, the electromagnetic heating control chip in the prior art has the problems of inaccurate current sampling, insufficient sensitivity of current surge response and the like, so that the IGBT protection mechanism in electromagnetic heating products such as an induction cooker and the like is unstable, and the requirements of users cannot be met.
Disclosure of Invention
Aiming at the defects in the prior art, the electromagnetic heating control chip provided by the invention solves the problems of inaccurate current sampling, insufficient current surge response and the like of the electromagnetic heating control chip in the prior art, and improves the accuracy of current detection and the surge response speed, thereby improving the stability of an IGBT protection mechanism in an electromagnetic heating product and meeting the requirements of users.
The invention provides an electromagnetic heating control chip, which comprises: the device comprises a controller, a pulse width generator, an analog-to-digital conversion module, a linear voltage stabilizer and a current detection module; the current detection module comprises a differential amplifier, a first comparator, a first resistor and a second resistor, wherein a normal phase input end of the differential amplifier is connected with a first end of an external sampling resistor when in use, a reverse phase input end of the differential amplifier is connected with a second end of the external sampling resistor when in use, an output end of the differential amplifier is also connected with a first end of the first resistor, a second end of the first resistor is connected with a first end of the second resistor, a second end of the second resistor is grounded, a first input end of the first comparator is connected with the linear voltage stabilizer, a second input end of the first comparator is connected with a first end of the second resistor, and the current detection module is used for collecting and amplifying voltages at two ends of the external sampling resistor to obtain a first sampling voltage and detecting a current surge; the analog-to-digital conversion module is connected with the output end of the differential amplifier, and is also connected with the controller and used for performing analog-to-digital conversion on the first sampling voltage and inputting the first sampling voltage into the controller, so that the controller obtains sampling current according to the first sampling voltage after the analog-to-digital conversion; the pulse width generator is connected with the output end of the first comparator, and is also connected with an external driving circuit when in use and used for controlling the working state of the external driving circuit according to the current surge state.
Optionally, the current detection module further includes: a first fixed end of the first sliding resistor is connected with the inverting input end of the differential amplifier, a second fixed end of the first sliding resistor is connected with the analog-to-digital conversion module, and a sliding end of the first sliding resistor is connected with the controller; and a first fixed end of the second sliding resistor is connected with the positive phase input end of the differential amplifier, a second fixed end of the second sliding resistor is connected with the bias voltage output end, and a sliding end of the second sliding resistor is connected with the controller.
Optionally, the current detection module further includes: a first end of the first switch is connected with the second input end of the first comparator, a second end of the first switch is connected with the first end of the second resistor, and a control end of the first switch is connected with the controller; a first end of the second switch is connected with a second input end of the first comparator, and a control end of the second switch is connected with the controller; and a first end of the third switch is connected with a second end of the second switch, a second end of the third switch is connected with an output end of the differential amplifier, and a control end of the third switch is connected with the controller.
Optionally, the current detection module further includes: and the input end of the first DAC module is connected with the output end of the linear voltage regulator, and the output end of the first DAC module is connected with the first input end of the first comparator.
Optionally, the current detection module further includes: a first end of the fourth switch is connected with the second fixed end of the second sliding resistor, a second end of the fourth switch is connected with the bias voltage output end, and a control end of the fourth switch is connected with the controller; and a first end of the fifth switch is connected with the second fixed end of the second sliding resistor, a second end of the fifth switch is grounded, and a control end of the fifth switch is connected with the controller.
Optionally, the control chip further includes: the second comparator, the second DAC module, the third comparator and the third DAC module; a first input end of the second comparator is connected with an output end of the second DAC module, a second input end of the second comparator is connected with a collector of an external IGBT when in use, and an output end of the second comparator is connected with the pulse width generator; a first input end of the third comparator is connected with an output end of the third DAC module, a second input end of the third comparator is connected with a second input end of the second comparator, and an output end of the third comparator is connected with the pulse width generator; and the input end of the second DAC module and the input end of the third DAC module are respectively connected with the output end of the linear voltage regulator.
Optionally, the control chip further includes: the second input end of the synchronous comparator is connected with the first sampling point when in use, the first input end of the synchronous comparator is connected with the second sampling point when in use, and the output end of the synchronous comparator is connected with the pulse width generator; the input end of the fourth DAC module is connected with the output end of the linear voltage regulator; and a first input end of the fourth comparator is connected with the output end of the fourth DAC module, a second input end of the fourth comparator is connected with a second input end of the second comparator, and an output end of the fourth comparator is connected with the pulse width generator.
Optionally, the control chip further includes: the input end of the fifth DAC module is connected with the output end of the linear voltage regulator; and a first input end of the fifth comparator is connected with an output end of the fifth DAC module, a second input end of the fifth comparator is connected with an external voltage detection point when in use, a second input end of the fifth comparator is also connected with the analog-to-digital conversion module, and an output end of the fifth comparator is connected with the pulse width generator.
Optionally, the control chip further includes: the input end of the sixth DAC module is connected with the output end of the linear voltage regulator; and a first input end of the sixth comparator is connected with a second input end of the fifth comparator, a second input end of the sixth comparator is connected with an output end of the sixth DAC module, an output end of the sixth comparator is connected with the pulse width generator, and an output end of the sixth comparator is further connected with the controller.
Optionally, the control chip further includes: the input end of the seventh DAC module is connected with the output end of the linear voltage regulator; and a first input end of the seventh comparator is connected with the first sampling point when in use, a second input end of the seventh comparator is connected with the output end of the seventh DAC module, an output end of the seventh comparator is connected with the pulse width generator, and an output end of the seventh comparator is further connected with the controller.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention detects the voltage signals at the two ends of the sampling resistor through the differential amplifier for amplification, can truly reflect the current waveform of the sampling resistor, removes the influence of external resistor capacitance on the amplification factor and the influence of inconsistent ground wire reference point potential, reduces peripheral components and improves the amplification precision of the amplifier and the accuracy of current detection.
2. The invention can effectively prevent common-mode interference in the circuit through the differential amplifier, does not need external capacitor shaping filtering, prevents the circuit from influencing the response time of surge, and improves the surge response speed, thereby improving the stability of an IGBT protection mechanism in an electromagnetic heating product and meeting the requirements of users.
3. The invention divides the output voltage of the differential amplifier by the first resistor and the second resistor and inputs the divided voltage to the comparator, so that the common-mode voltage of the comparator is always kept below 1/2 of the working voltage, and the comparison precision of the comparator is improved.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without inventive exercise.
Fig. 1 is a schematic structural diagram of an electromagnetic heating control chip according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of another electromagnetic heating control chip according to an embodiment of the present invention;
fig. 3 is a circuit schematic diagram of a DAC module according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are some embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application. Like numbered functional units in the examples of the present invention have the same and similar structure and function.
Example one
Fig. 1 is a schematic structural diagram of an electromagnetic heating control chip according to an embodiment of the present invention; as shown in fig. 1, the electromagnetic heating control chip provided by the present invention includes:
a controller, a pulse width generator, an analog-to-digital conversion module, a linear regulator and a current detection module 110;
the current detection module 110 includes a differential amplifier PGA, a first comparator CM1, a first resistor R1, and a second resistor R2, where a positive phase input terminal of the differential amplifier PGA is connected to a first end of an external sampling resistor when in use, a negative phase input terminal of the differential amplifier PGA is connected to a second end of the external sampling resistor when in use, an output terminal of the differential amplifier PGA is further connected to a first end of the first resistor R1, a second end of the first resistor R1 is connected to a first end of the second resistor R2, a second end of the second resistor R2 is grounded, a first input terminal of the first comparator CM1 is connected to the linear regulator, a second input terminal of the first comparator CM1 is connected to a first end of the second resistor R2, and the current detection module 110 is configured to collect and amplify voltages at two ends of the external sampling resistor to obtain a first sampling voltage and is further configured to detect a current surge;
the analog-to-digital conversion module is connected with the output end of the differential amplifier PGA, and is also connected with the controller and used for performing analog-to-digital conversion on the first sampling voltage and inputting the first sampling voltage into the controller, so that the controller obtains sampling current according to the first sampling voltage after the analog-to-digital conversion;
the pulse width generator is connected with the output end of the first comparator CM1, and is also connected with an external driving circuit when in use, and is used for controlling the working state of the external driving circuit according to the current surge state.
It should be noted that, in the electromagnetic heating control chip provided in this embodiment, the voltage signals at two ends of the external sampling resistor are differentially sampled through two input ends of the differential amplifier PGA, and the voltage signals are amplified by corresponding multiples and then input to the analog-to-digital conversion module, so that the analog-to-digital conversion module performs analog-to-digital conversion on the first sampling voltage and inputs the first sampling voltage to the controller, and the controller obtains a sampling current according to the first sampling voltage after the analog-to-digital conversion.
Further, in this embodiment, the voltage signals at two ends of the external sampling resistor are amplified by corresponding multiples and then provided to the comparator for surge current monitoring through the divided voltages of the first resistor R1 and the second resistor R2, and when the sampling voltage input to the comparator is greater than the reference voltage output by the linear regulator, the comparator turns over and outputs an interrupt signal to the pulse width generator, so that the pulse width generator controls the external driving circuit to be turned off, thereby realizing current surge protection of the external IGBT.
Compared with the prior art, the invention has the following beneficial effects:
1. the invention detects the voltage signals at the two ends of the sampling resistor through the differential amplifier PGA to amplify, can truly reflect the current waveform of the sampling resistor, removes the influence of external resistor capacitance on the amplification factor and the influence of inconsistent ground wire reference point potential, reduces peripheral components and improves the amplification precision of the amplifier and the accuracy of current detection.
2. The invention can effectively prevent common mode interference in the circuit through the differential amplifier PGA, does not need external capacitor shaping filtering, prevents the circuit from influencing the response time of surge, and improves the surge response speed, thereby improving the stability of an IGBT protection mechanism in an electromagnetic heating product and meeting the requirements of users.
3. According to the invention, the output voltage of the differential amplifier PGA is divided by the first resistor R1 and the second resistor R2 and then input to the comparator, so that the common-mode voltage of the comparator is always kept below 1/2 of the working voltage, and the comparison precision of the comparator is improved.
Example two
Fig. 2 is a schematic structural diagram of another electromagnetic heating control chip according to an embodiment of the present invention; as shown in fig. 2, the current detection module 110 provided in this embodiment further includes:
a first fixed end of the first sliding resistor VR1 is connected to the inverting input end of the differential amplifier PGA, a second fixed end of the first sliding resistor VR1 is connected to the analog-to-digital conversion module, and a sliding end of the first sliding resistor VR1 is connected to the controller; a second sliding resistor VR2, a first fixed end of the second sliding resistor VR2 is connected to the positive input end of the differential amplifier PGA, a second fixed end of the second sliding resistor VR2 is connected to the bias voltage output end, and a sliding end of the second sliding resistor VR2 is connected to the controller.
It should be noted that, the invention divides and limits the voltage of the input end of the differential amplifier PGA through two voltage dividing resistors, so as to prevent the differential amplifier PGA from being burned out by an excessive current; the invention also controls the first sliding resistor VR1 and the second sliding resistor VR2 through a controller, thereby achieving the purpose of adjusting the amplification factor of the differential amplifier PGA.
In this embodiment, the current detecting module 110 further includes: a first switch S1, a first end of the first switch S1 is connected to a second input end of the first comparator CM1, a second end of the first switch S1 is connected to a first end of the second resistor R2, and a control end of the first switch S1 is connected to the controller; a second switch S2, a first end of the second switch S2 is connected to a second input end of the first comparator CM1, and a control end of the second switch S2 is connected to the controller; a first end of the third switch S3 is connected to a second end of the second switch S2, a second end of the third switch S3 is connected to an output end of the differential amplifier PGA, and a control end of the third switch S3 is connected to the controller.
It should be noted that, in this embodiment, the controller controls the first switch S1, the second switch S2, and the third switch S3 to be turned on or off according to the current operating voltage of the detection circuit, so as to select different voltages to be input to the comparator for comparison, which not only improves the comparison accuracy of the comparator in different application scenarios, but also improves the application range of the detection circuit.
In this embodiment, the current detecting module 110 further includes: the input end of the first DAC module DAC1 is connected with the output end of the linear voltage regulator, and the output end of the first DAC module DAC1 is connected with the first input end of the first comparator CM 1. In this embodiment, a plurality of reference voltages are provided to the first comparator CM1 through the first DAC module DAC 1.
In this embodiment, the current detection module 100 further includes: a fourth switch S4, a first end of the fourth switch S4 is connected to a second fixed end of the second sliding resistor VR2, a second end of the fourth switch S4 is connected to the bias voltage output end, and a control end of the fourth switch S4 is connected to the controller; a fifth switch S5, a first end of the fifth switch S5 is connected to the second fixed end of the second sliding resistor VR2, a second end of the fifth switch S5 is grounded, and a control end of the fifth switch S5 is connected to the controller.
It should be noted that in this embodiment, the controller controls the fourth switch S4 and the fifth switch S5 to open and close, so that the bias voltage of the differential amplifier PGA can be selected, and the bias voltage can be adaptively selected according to the application scenario of the inspection circuit, thereby improving the application range.
EXAMPLE III
As shown in fig. 2, the control chip provided in this embodiment further includes: a second comparator CM2, a second DAC module DAC2, a third comparator CM3 and a third DAC module DAC3; a first input end of the second comparator CM2 is connected with an output end of the second DAC module DAC2, a second input end of the second comparator CM2 is connected with a collector of an external IGBT when in use, and an output end of the second comparator CM2 is connected with the pulse width generator; a first input end of the third comparator CM3 is connected to an output end of the third DAC module DAC3, a second input end of the third comparator CM3 is connected to a second input end of the second comparator CM2, and an output end of the third comparator CM3 is connected to the pulse width generator; and the input end of the second DAC module DAC2 and the input end of the third DAC module DAC3 are respectively connected with the output end of the linear voltage regulator.
It should be noted that, in this embodiment, the second comparator CM2, the third comparator CM3 and the pulse width generator are linked, and the pulse width output by the pulse width generator is reduced by hardware, so as to reduce the on-time of the IGBT, or the IGBT is turned off by hardware control; in this embodiment, the first threshold voltage is smaller than the second threshold voltage, and when the input voltage of the second comparator CM2 is greater than the first threshold voltage set by the user, the second comparator CM2 is turned over, and outputs a first interrupt signal to the pulse width generator, so that the pulse width generator reduces the output pulse width according to the first interrupt signal, thereby reducing the IGBT on-time and further achieving the purpose of reducing the IGBT voltage. Further, when the input voltage of the third comparator CM3 is greater than the second threshold voltage set by the user, the third comparator CM3 is inverted and outputs a second interrupt signal to the pulse width generator, so that the pulse width generator turns off the IGBT according to the second interrupt signal, thereby preventing the IGBT from being damaged by reducing the IGBT on-time for a long time when the overvoltage seriously exceeds the standard; the first interrupt signal is the first comparison result, and the second interrupt signal is the second comparison result.
The embodiment has the following beneficial effects: according to the invention, the second comparator CM2 and the third comparator CM3 form two-stage overvoltage protection, the input voltage of the same voltage detection port is subjected to multi-stage judgment, and when the input voltage exceeds the threshold voltage of the second comparator CM2, the turn-on time of the IGBT is reduced, so that the purpose of reducing the voltage of the IGBT is achieved; when the input voltage exceeds the threshold voltage of the third comparator CM3, the IGBT is turned off, so that the situation that the IGBT is damaged by reducing longer IGBT conducting time when overvoltage seriously exceeds the standard is prevented, therefore, the invention perfects an IGBT overvoltage protection mechanism and improves the accuracy of IGBT voltage control.
In this embodiment, the control chip further includes:
and the input end of the counter is connected with the output end of the second comparator CM2, the output end of the counter is connected with the pulse width generator, and the counter is used for detecting the accumulated times of the second comparator CM2 outputting the first comparison result in a preset time length, and outputting a third comparison result when the accumulated times is greater than or equal to the preset times, so that the pulse width generator controls the turn-off of the IGBT according to the third comparison result.
It should be noted that, when the voltage of the IGBT exceeds the first threshold voltage for multiple times within a certain time period, and the number of times of the flip of the comparator detected by the counter exceeds the preset number of times, the pulse width generator may also turn off the IGBT, so that the IGBT may be automatically turned off even if the IGBT works above the first threshold voltage set by the first comparator CM1 for a long time, thereby effectively protecting the IGBT and preventing long-term overvoltage damage.
Example four
As shown in fig. 2, based on the third embodiment, the control chip provided in this embodiment further includes: the second input end of the synchronous comparator CM0 is connected with the first sampling point when in use, the first input end of the synchronous comparator CM0 is connected with the second sampling point when in use, and the output end of the synchronous comparator CM0 is connected with the pulse width generator; the input end of the fourth DAC module DAC4 is connected with the output end of the linear voltage regulator; a fourth comparator CM4, a first input terminal of the fourth comparator CM4 is connected to the output terminal of the fourth DAC module DAC4, a second input terminal of the fourth comparator CM4 is connected to the second input terminal of the second comparator CM2, and an output terminal of the fourth comparator CM4 is connected to the pulse width generator.
The fourth DAC module DAC4 is used for outputting a first threshold voltage; the first input end of the synchronous comparator CM0 is connected with the first sampling point when in use, and the second input end of the synchronous comparator CM0 is connected with the second sampling point when in use, and is used for outputting a first comparison result when a first sampling voltage of the first sampling point is equal to a second sampling voltage of the second sampling point;
a first input terminal of the fourth comparator CM4 is connected to the second input terminal of the synchronous comparator CM0, and a second input terminal of the fourth comparator CM4 is connected to the fourth DAC module DAC4, and is configured to compare the second sampling voltage with the first threshold voltage, and output a second comparison result when the second sampling voltage is greater than the first threshold voltage;
the first input end of the pulse width generator is connected with the output end of the synchronous comparator CM0, the second input end of the pulse width generator is connected with the output end of the fourth comparator CM4, and the output end of the pulse width generator is connected with the grid electrode of the external IGBT when in use and used for increasing the conduction duration of the external IGBT when receiving the first comparison result and the second comparison result at the same time.
It should be noted that, in this embodiment, the synchronous comparator CM0 compares the first sampling voltage and the second sampling voltage in real time, and when the first sampling voltage and the second sampling voltage are equal, a first comparison result is sent to the pulse width generator to trigger the external IGBT to be turned on; further, in this embodiment, the fourth comparator CM4 compares the second sampling voltage with the first threshold voltage in real time, and sends a second comparison result to the pulse width generator when the second sampling voltage is greater than the first threshold voltage; in this embodiment, when the pulse width generator receives the first comparison result output by the synchronous generator and simultaneously receives the second comparison result output by the fourth comparator CM4, the pulse width generator increases the on-time of the IGBT, so as to reduce the on-step voltage of the IGBT, where the on-step voltage is a difference between the second sampling voltage and the first threshold voltage.
The embodiment has the following beneficial effects: according to the invention, the synchronous comparator CM0, the fourth comparator CM4 and the pulse width generator are used for monitoring and controlling the linkage of the external IGBT in real time, so that the conduction step voltage of the IGBT can be detected in real time, and when the conduction step voltage of the IGBT is detected to exceed the preset range, the conduction step voltage is adjusted in time by controlling the conduction time of the IGBT, so that the accurate control of the conduction step voltage of the IGBT is realized, and the purpose of effectively protecting the IGBT is achieved.
EXAMPLE five
As shown in fig. 2, the control chip provided in this embodiment further includes: the control chip further comprises: the input end of the fifth DAC module DAC5 is connected with the output end of the linear voltage regulator; and a fifth comparator CM5, a first input end of the fifth comparator CM5 is connected to the output end of the fifth DAC module DAC5, a second input end of the fifth comparator CM5 is connected to an external voltage detection point when in use, a second input end of the fifth comparator CM5 is further connected to the analog-to-digital conversion module, and an output end of the fifth comparator CM5 is connected to the pulse width generator.
In this embodiment, the control chip further includes: the input end of the sixth DAC module DAC6 is connected with the output end of the linear voltage regulator; and a sixth comparator CM6, wherein a first input end of the sixth comparator CM6 is connected to a second input end of the fifth comparator CM5, a second input end of the sixth comparator CM6 is connected to an output end of the sixth DAC module DAC6, an output end of the sixth comparator CM6 is connected to the pulse width generator, and an output end of the sixth comparator CM6 is further connected to the controller.
In this embodiment, the control chip further includes: the input end of the seventh DAC module DAC7 is connected with the output end of the linear voltage regulator; and a seventh comparator CM7, a first input terminal of the seventh comparator CM7 is connected to the first sampling point when in use, a second input terminal of the seventh comparator CM7 is connected to the output terminal of the seventh DAC module DAC7, an output terminal of the seventh comparator CM7 is connected to the pulse width generator, and an output terminal of the seventh comparator CM7 is further connected to the controller.
It should be noted that, in this embodiment, the second input terminal of the fifth comparator CM5 is connected to the external voltage detection point when in use, and the second input terminal of the fifth comparator CM5 is further connected to the analog-to-digital converter, so that voltage detection at the voltage detection point can be simultaneously achieved, and voltage surge detection can also be performed; and comparing the input voltage input into the fifth comparator CM5 with the threshold voltage input into the fifth DAC module DAC5, and when the input voltage is greater than the threshold voltage, outputting a first comparison result to the pulse width generator by the fifth comparator CM5, so that the pulse width generator controls the external drive circuit to be switched off, thereby achieving the purpose of protecting the IGBT.
It should be further noted that, in order to feed back the voltage waveform of the first sampling point in real time, the present embodiment compares the first sampling voltage with the threshold voltage output by the seventh DAC module DAC7 in real time through the seventh comparator CM7, and sends the comparison result to the controller, so that the controller draws the voltage waveform of the first sampling point according to the comparison result and the preset algorithm rule, where the controller may calculate the voltage waveform of the first sampling point through related algorithms in the prior art. Similarly, the controller may draw the voltage waveform of the external voltage detection point according to the comparator result output by the sixth comparator CM6 and a preset algorithm rule.
EXAMPLE six
As shown in fig. 3, each DAC module 200 provided in the present embodiment includes: a voltage dividing unit 210, a selection chip and a plurality of selection branches 220; the voltage dividing unit 210 is respectively connected to the plurality of selecting branches 220, an output end of the voltage dividing unit 210 is an output end of each DAC module, an input end of the selecting chip is connected to the controller, a plurality of output ends of the selecting chip are respectively connected to the plurality of selecting branches 220, and the plurality of selecting branches 220 are further connected to an output end of the linear regulator; the selection chip is configured to control the voltage dividing unit 210 to output a corresponding target voltage through the plurality of selection branches 220 according to the voltage parameter output by the controller.
In the present embodiment, each selection branch 220 includes: a first end of the third resistor R3 is connected with the output end of the selection chip; a gate of the triode Q1 is connected with a second end of the third resistor R3, and an emitter of the triode Q1 is connected with an output end of the linear voltage regulator; and a fourth resistor R4, a first end of the fourth resistor R4 is connected to the collector of the triode Q1, and a second end of the fourth resistor R4 is connected to the voltage dividing unit 210.
In this embodiment, the voltage dividing unit includes: the voltage dividing resistors are connected in series, and the plurality of selection branches are electrically connected with intersection points between two adjacent voltage dividing resistors respectively.
It should be noted that, in this embodiment, a linear regulator is used to regulate a voltage output by an external power supply to obtain a first voltage, and then the first voltage is converted into a plurality of different target voltages by the plurality of DACs to provide corresponding reference voltages for the plurality of comparators, and the linear regulator, the plurality of DAC modules, the controller and the plurality of comparators are integrated in the same chip, which is equivalent to a built-in linear regulator, so that the influence of the precision of an external power supply module and the fluctuation of the output voltage of the external power supply module on the reference voltage of the comparators in the prior art is eliminated, thereby improving the comparison precision of the comparators; in this embodiment, each DAC module can be adjusted by the controller to convert the first voltage into a plurality of different voltage values, and the step control of the reference voltage of the comparator can be controlled within 20MV by using the 8BIT DAC module, so that the step amplitude is reduced, the control and debugging of the controller are facilitated, peripheral components do not need to be added, and the volume and the cost of the control circuit are reduced.
It should be further noted that, the selection chip U2 sends a corresponding control signal to the target selection branch 220 according to the voltage parameter sent by the controller U1, so that the target selection branch 220 is turned on, the first voltage output by the linear regulator is connected to the voltage dividing unit 210 for voltage division, so as to obtain a corresponding target voltage, and the turning on of each selection branch 220 enables the voltage dividing unit 210 to output different target voltages, so as to achieve the purpose that the DAC module can output multiple target voltages.
EXAMPLE seven
As shown in fig. 2, in this embodiment, the pulse width generator is further connected to the analog-to-digital conversion module, and when the pulse width generator outputs a rising edge, a falling edge, or a central point of a pulse signal, the pulse width generator sends a trigger signal to the analog-to-digital conversion module, so that the analog-to-digital conversion module performs analog-to-digital conversion when receiving the trigger signal, and further, the controller can accurately detect a working current of the IGBT when the IGBT is turned on or off.
In this embodiment, the analog-to-digital conversion module further has functions of automatic triggering, automatic summing, and maximum and minimum value calculation, so that the frame measurement speed of the analog-to-digital conversion module on the voltage and current waveforms is further improved, and the peak values and effective values of the voltage and current can be accurately fed back.
It is noted that, in this document, relational terms such as "first" and "second," and the like, may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrases "comprising a," "8230," "8230," or "comprising" does not exclude the presence of additional like elements in a process, method, article, or apparatus that comprises the element.
The foregoing are merely exemplary embodiments of the present invention, which enable those skilled in the art to understand or practice the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (10)
1. An electromagnetic heating control chip, the control chip comprising:
the device comprises a controller, a pulse width generator, an analog-to-digital conversion module, a linear voltage stabilizer and a current detection module;
the current detection module comprises a differential amplifier, a first comparator, a first resistor and a second resistor, wherein a normal phase input end of the differential amplifier is connected with a first end of an external sampling resistor when in use, a reverse phase input end of the differential amplifier is connected with a second end of the external sampling resistor when in use, an output end of the differential amplifier is also connected with a first end of the first resistor, a second end of the first resistor is connected with a first end of the second resistor, a second end of the second resistor is grounded, a first input end of the first comparator is connected with the linear voltage stabilizer, a second input end of the first comparator is connected with a first end of the second resistor, and the current detection module is used for collecting and amplifying voltages at two ends of the external sampling resistor to obtain a first sampling voltage and detecting a current surge;
the analog-to-digital conversion module is connected with the output end of the differential amplifier, and is also connected with the controller and used for performing analog-to-digital conversion on the first sampling voltage and inputting the first sampling voltage into the controller, so that the controller obtains sampling current according to the first sampling voltage after the analog-to-digital conversion;
the pulse width generator is connected with the output end of the first comparator, and is also connected with an external driving circuit when in use and used for controlling the working state of the external driving circuit according to the current surge state.
2. The electromagnetic heating control chip of claim 1, wherein the current detection module comprises:
a first fixed end of the first sliding resistor is connected with the inverting input end of the differential amplifier, a second fixed end of the first sliding resistor is connected with the analog-to-digital conversion module, and a sliding end of the first sliding resistor is connected with the controller;
and a first fixed end of the second sliding resistor is connected with the positive phase input end of the differential amplifier, a second fixed end of the second sliding resistor is connected with the bias voltage output end, and a sliding end of the second sliding resistor is connected with the controller.
3. The electromagnetic heating control chip of claim 1, wherein the current detection module further comprises:
a first end of the first switch is connected with the second input end of the first comparator, a second end of the first switch is connected with the first end of the second resistor, and a control end of the first switch is connected with the controller;
a first end of the second switch is connected with a second input end of the first comparator, and a control end of the second switch is connected with the controller;
and a first end of the third switch is connected with a second end of the second switch, a second end of the third switch is connected with an output end of the differential amplifier, and a control end of the third switch is connected with the controller.
4. The electromagnetic heating control chip of claim 1, wherein the current detection module further comprises:
and the input end of the first DAC module is connected with the output end of the linear voltage regulator, and the output end of the first DAC module is connected with the first input end of the first comparator.
5. The electromagnetic heating control chip of claim 2, wherein the current detection module further comprises:
a first end of the fourth switch is connected with the second fixed end of the second sliding resistor, a second end of the fourth switch is connected with the bias voltage output end, and a control end of the fourth switch is connected with the controller;
and a first end of the fifth switch is connected with the second fixed end of the second sliding resistor, a second end of the fifth switch is grounded, and a control end of the fifth switch is connected with the controller.
6. The electromagnetic heating control chip of claim 1, wherein the control chip further comprises:
the second comparator, the second DAC module, the third comparator and the third DAC module;
a first input end of the second comparator is connected with an output end of the second DAC module, a second input end of the second comparator is connected with a collector of an external IGBT when in use, and an output end of the second comparator is connected with the pulse width generator;
a first input end of the third comparator is connected with an output end of the third DAC module, a second input end of the third comparator is connected with a second input end of the second comparator, and an output end of the third comparator is connected with the pulse width generator;
and the input end of the second DAC module and the input end of the third DAC module are respectively connected with the output end of the linear voltage regulator.
7. The electromagnetic heating control chip of claim 6, wherein the control chip further comprises:
the second input end of the synchronous comparator is connected with the first sampling point when in use, the first input end of the synchronous comparator is connected with the second sampling point when in use, and the output end of the synchronous comparator is connected with the pulse width generator;
the input end of the fourth DAC module is connected with the output end of the linear voltage regulator;
and a first input end of the fourth comparator is connected with the output end of the fourth DAC module, a second input end of the fourth comparator is connected with a second input end of the second comparator, and an output end of the fourth comparator is connected with the pulse width generator.
8. The electromagnetic heating control chip of claim 1, wherein the control chip further comprises:
the input end of the fifth DAC module is connected with the output end of the linear voltage regulator;
and a first input end of the fifth comparator is connected with the output end of the fifth DAC module, a second input end of the fifth comparator is connected with an external voltage detection point when in use, a second input end of the fifth comparator is also connected with the analog-to-digital conversion module, and an output end of the fifth comparator is connected with the pulse width generator.
9. The electromagnetic heating control chip of claim 8, wherein the control chip further comprises:
the input end of the sixth DAC module is connected with the output end of the linear voltage regulator;
and a first input end of the sixth comparator is connected with a second input end of the fifth comparator, a second input end of the sixth comparator is connected with an output end of the sixth DAC module, an output end of the sixth comparator is connected with the pulse width generator, and an output end of the sixth comparator is further connected with the controller.
10. The electromagnetic heating control chip of claim 1, wherein the control chip further comprises:
the input end of the seventh DAC module is connected with the output end of the linear voltage regulator;
and a first input end of the seventh comparator is connected with the first sampling point when in use, a second input end of the seventh comparator is connected with the output end of the seventh DAC module, an output end of the seventh comparator is connected with the pulse width generator, and an output end of the seventh comparator is further connected with the controller.
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| CN202110410824.6A CN113099566B (en) | 2021-04-16 | 2021-04-16 | Electromagnetic heating control chip |
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| CN202110410824.6A CN113099566B (en) | 2021-04-16 | 2021-04-16 | Electromagnetic heating control chip |
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| CN2859984Y (en) * | 2005-10-27 | 2007-01-17 | 深圳市拓邦电子科技股份有限公司 | Electromagnetic oven control device |
| CN101752845B (en) * | 2008-12-12 | 2012-07-04 | 深圳市鑫汇科科技有限公司 | Voltage and current surge protection method for electromagnetic oven and circuit thereof |
| CN104717772B (en) * | 2015-03-16 | 2017-10-17 | 昂宝电子（上海）有限公司 | Control circuit and control method for electromagnetic oven overcurrent protection |
| CN105680708A (en) * | 2015-11-20 | 2016-06-15 | 芜湖锐芯电子科技有限公司 | Current mode synchronous rectification PWM control circuit |
| CN112104348A (en) * | 2020-08-31 | 2020-12-18 | 深圳市优必选科技股份有限公司 | Protection circuit of MOS pipe |
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