CN114498548B - Overcurrent protection method and device - Google Patents
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- CN114498548B CN114498548B CN202210073903.7A CN202210073903A CN114498548B CN 114498548 B CN114498548 B CN 114498548B CN 202210073903 A CN202210073903 A CN 202210073903A CN 114498548 B CN114498548 B CN 114498548B
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- 238000005070 sampling Methods 0.000 claims description 39
- 239000003990 capacitor Substances 0.000 claims description 19
- 238000011084 recovery Methods 0.000 claims description 17
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
- H02H3/087—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current for dc applications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
- H02H7/12—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
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Abstract
The invention discloses an overcurrent protection method and device, comprising the steps of respectively comparing a power supply output current value Io with a fast protection threshold IF and a slow protection threshold IS which are set previously, and IF the power supply output current value Io IS larger than the fast protection threshold, immediately blocking a PWM generator by an MCU to realize wave-sealing protection; IF the Io IS between IS and IF, the MCU will not immediately block the PWM generator, and the PWM generator IS blocked and protected by blocking the PWM generator when detecting that the Io IS between IS and IF in a continuous a switching period. The power supply output current value is logically processed according to the protection parameters, so that multistage and time-sharing protection is effectively realized, the rapid protection during high impact current is ensured, and the power supply can normally work during low impact current without error protection.
Description
Technical Field
The invention relates to the technical field of electronic equipment for measurement and test, in particular to an overcurrent protection method and device.
Background
At present, the following methods are mostly adopted in the power output overcurrent protection method:
(1) The hardware samples and outputs the current value, and compare with protecting the reference voltage through the comparator, thus realize the fast protection, as the invention patent application of publication No. CN1848577A discloses an overcurrent protection circuit, adopt the hardware circuit to realize the overcurrent protection, the advantage is that can protect fast, the disadvantage is not flexible enough, once the hardware parameter is confirmed, protect the threshold value and confirm promptly, can't set up a plurality of threshold values, realize the multistage protection. In addition, since the protection reference voltage is provided by adopting a resistor voltage division mode, the resistor precision is generally low, and temperature drift and ripple exist, so that high-precision protection is difficult to realize.
(2) The method comprises the steps of sampling an output current value, calculating the output current value through an ADC chip and an MCU, comparing the output current value with a preset protection value, and thus realizing protection of an overcurrent protection circuit with an adjustable overcurrent threshold as disclosed in the patent of the invention with the publication number of CN 103219694B. The circuit overcurrent protection is realized in a digital control mode, but the protection logic immediately protects the machine from halt after detecting that the output current value is larger than a preset protection value, and the protection threshold is generally only one, and no multi-stage protection exists.
In order to ensure that the internal devices are not damaged under the overcurrent condition, manufacturers can keep the protection threshold value relatively conservative and cannot set the protection threshold value too high. In addition, under the condition that the output voltage is established, capacitive load is suddenly added, so that the equipment can easily report output overcurrent protection and stop, and the equipment at the user side can not work normally. This is very common in the field of test electronics, because for the test electronics, the load is mostly AC-DC, DC-AC, etc. power products, such as photovoltaic inverters, energy storage inverters, vehicle DC-DC, OBC, etc., are commonly used, and such power products often have a capacitor with a larger capacitance added at the input end.
Disclosure of Invention
The technical problem to be solved by the invention is how to effectively realize the grading protection of the output current.
The invention solves the technical problems by the following technical means:
in a first aspect, an over-current protection method is adopted, and the method includes:
s10, sampling to obtain an output current value Io of a power supply;
s20, judging whether the Io is more than or equal to the IF, IF the IF is a rapid protection threshold, executing the step S60 IF the IF is the rapid protection threshold, and otherwise executing the step S30;
s30, judging whether the Io IS more than or equal to IS, if the IS IS a slow protection threshold, executing a step S40 if the IS IS a slow protection threshold, and if the IS IS not a slow protection threshold, executing a step S50;
s40, enabling N=N+1, judging whether N is more than or equal to a, wherein N represents a slow protection period count value, a represents a slow protection period number, if yes, executing a step S60, and if not, executing a step S10;
s50, resetting the N value, and then executing the step S10;
s60, executing a protection action, blocking the PWM generator, and then executing step S10.
By setting each protection parameter in the MCU equipment and carrying out logic processing on the power supply output current value according to the protection parameter, multistage and time-sharing protection is effectively realized, so that the rapid protection in the high impact current is ensured, and the power supply can normally work in the low impact current without error protection.
Further, the method further comprises:
judging whether the MCU equipment is in a protection state or not;
if not, executing the step S50;
if the current value is in the protection state, judging whether the current value satisfies Io < IR, wherein IR is a recovery current value;
if yes, the PWM generator is recovered, and the step S50 is executed;
if not, the step S50 is directly performed.
Further, the sampling to obtain the output current value Io of the power supply includes:
the power supply output current is filtered by a filter capacitor and then sampled by a sampling resistor to obtain a sampling voltage value U1;
amplifying the sampling voltage value U1 by using an operational amplifier to obtain a voltage value U2;
the voltage value U2 enters an ADC sampling circuit through a differential circuit to obtain the output current value Io.
In a second aspect, an overcurrent protection device is adopted, the device comprises a power supply, a current acquisition circuit, MCU equipment and a PWM generator, the power supply is connected with the MCU equipment through the current acquisition circuit, and the MCU equipment is connected with the power supply through the PWM generator;
wherein, be provided with slow protection threshold IS, fast protection threshold IF and slow protection cycle number a in the MCU equipment, the MCU equipment includes:
the acquisition module is used for acquiring an output current value Io of the power supply;
the first judging module is used for judging whether the Io is more than or equal to the IF;
the second judging module IS used for judging whether the Io IS more than or equal to IS or not when the output result of the first judging module IS NO;
the third judging module is used for enabling N=N+1 and judging whether N is more than or equal to a or not when the output result of the second judging module is yes, wherein N represents a slow protection period count value;
the first determining module is used for executing a protection action and blocking the PWM generator when the output result of the first judging module and the third judging module is yes; and the control module is used for controlling the N value to be cleared when the output result of the second judging module is NO.
Further, the MCU device is further provided with a recovery current value IR, and the MCU device further includes:
a fourth judging module, configured to judge whether the MCU device is in a protection state;
the second determining module is used for controlling the N value to be cleared when the output result of the fourth judging module is NO;
a fifth judging module, configured to judge whether Io < IR is satisfied or not when the output result of the fourth judging module is yes, where IR is a recovery current value;
the third determining module is used for recovering the PWM generator and controlling the N value to be cleared when the output result of the fifth judging module is yes; and the control module is used for controlling the N value to be cleared when the output result of the fifth judging module is NO.
Further, the current acquisition circuit includes a capacitor, a sampling resistor, an operational amplifier, a differential circuit, and an ADC sampling circuit, wherein:
the capacitor is connected in parallel with two ends of the power supply, the two ends of the capacitor are connected in parallel with a load, a sampling resistor is connected in series between the capacitor and the load, the sampling resistor is connected with the differential circuit through the operational amplifier, and the differential circuit is connected with the MCU equipment through the ADC sampling circuit.
In a third aspect, an apparatus is employed, the apparatus comprising a memory, a processor; wherein the processor runs a program corresponding to the executable program code by reading the executable program code stored in the memory for implementing the method as described above.
The invention has the advantages that:
(1) According to the invention, through setting each protection parameter in the MCU equipment and carrying out logic processing on the power supply output current value according to the protection parameters, multistage and time-sharing protection is effectively realized, so that the rapid protection under high impact current is ensured, and the power supply can normally work under low impact current without error protection.
(2) In consideration of the conditions similar to the sudden capacitive load or short circuit, the recovery current value is set in the MCU equipment, so that the quick protection can be realized, the equipment is not damaged, the equipment is not stopped under the working conditions, the normal work is still ensured, and the normal running of the user test is ensured.
(3) By adopting a high-speed operational amplifier and MCU digital control mode, not only can high-speed protection be realized, but also high-precision protection can be realized due to the low-temperature drift and high-precision characteristics of the operational amplifier, sampling resistor and the like.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
FIG. 1 is a flow chart of an over-current protection method according to a first embodiment of the invention;
FIG. 2 is an overall flow chart of an over-current protection method according to a first embodiment of the invention;
FIG. 3 is a diagram showing the relationship between the fast protection action logic, the protection current, the restart current and time according to the first embodiment of the present invention;
FIG. 4 is a diagram showing the relationship between the slow protection logic, the protection current, the restart current and time according to the first embodiment of the present invention;
FIG. 5 is a block diagram of an overcurrent protection device according to a second embodiment of the invention;
fig. 6 is a block diagram of an MCU device according to the second embodiment of the present invention.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions in the embodiments of the present invention will be clearly and completely described in the following in conjunction with the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
As shown in fig. 1, a first embodiment of the present invention discloses an over-current protection method for being executed on an MCU device, the method comprising the steps of:
s10, sampling to obtain an output current value Io of a power supply;
s20, judging whether the Io is more than or equal to the IF, IF the IF is a rapid protection threshold, executing the step S60 IF the IF is the rapid protection threshold, and otherwise executing the step S30;
s30, judging whether the Io IS more than or equal to IS, if the IS IS a slow protection threshold, executing a step S40 if the IS IS a slow protection threshold, and if the IS IS not a slow protection threshold, executing a step S50;
s40, enabling N=N+1, judging whether N is more than or equal to a, wherein N represents a slow protection period count value, a represents a slow protection period number, if yes, executing a step S60, and if not, executing a step S10;
s50, resetting the N value, and then executing the step S10;
s60, executing a protection action, blocking the PWM generator, and then executing step S10.
It should be noted that, the fast protection threshold IF represents the current limit that the device can bear in a very short time, so as to make fast protection, so that when a large current appears in the device, the output IS cut off fast, and the device IS protected, and the slow protection threshold IS represents that when the output current of the device IS between the current and IF, the device IS allowed to work in a short time, this time IS a×t, and depends on the current situation that the power device in the device can actually bear.
It should be noted that, the MCU device judges the output current value Io of the power supply, IF the output current value Io is greater than or equal to the fast protection threshold IF, the fast protection unit of the MCU device can quickly respond, block the PWM generator, and stop generating waves. The setting of the fast protection threshold IF in the embodiment can effectively protect the safety of the equipment under the impact of large current.
IF the output current value Io IS smaller than the fast protection threshold value IF, the MCU equipment performs the next judgment, namely, the Io IS compared with the slow protection threshold value IS, IF the output current value Io IS larger than or equal to the slow protection threshold value IS, the slow protection period count value N IS increased by 1, and meanwhile, whether the slow protection period count value N IS larger than or equal to the set slow protection period number a IS judged, IF N IS larger than or equal to a, the logic unit of the MCU performs protection action, the PWM generator IS blocked, and wave generation IS stopped; IF N IS smaller than a, the overcurrent value IS between IS and IF, and the duration of the overcurrent IS within the range which can be born by the equipment, so that the equipment can not perform protection action at the moment and still can normally output.
It should be noted that, the values of the fast protection threshold IF and the slow protection threshold IS are mainly based on specifications from power devices inside the device. The main power devices inside the general power supply products are MOSFETs or diodes, and the safety working range of the products is given in specifications, namely SOA (Safe Operating Area). And determining a fast protection threshold IF and a slow protection threshold IS according to actual needs and an SOA.
It should be noted that, when the fast protection threshold and the slow protection threshold are valued, normal output of the device IS not affected, that IS, the value of IS cannot be too small, a certain margin IS put on the basis of rated maximum output current of the device, meanwhile, safety of devices in the device IS guaranteed, that IS, the value of IF cannot be too large, and specific value and protection action time are determined according to an SOA in a device manual.
It should be noted that, when the slow protection cycle number a is set in this embodiment, the maximum duration that the device can normally operate under the fast protection threshold IF current needs to be fully evaluated, and the action time of the slow protection, that is, the slow protection cycle number a, is determined based on the maximum duration.
It should be noted that, the cycle number "a" refers to a PWM cycle, that is, a switching cycle of the dc power supply, and the cycle number is determined mainly according to SOA data in a device manual, for example, a switching frequency of the dc power supply is 100kHz, and the switching cycle is t=1/f=1/100000=10 uS, which is also the minimum control cycle of most dc power supplies. The setting of the slow protection threshold IS and the slow protection period number a can effectively ensure the normal and stable operation of the equipment under the short-time overcurrent condition, and can effectively prevent the occurrence of overcurrent protection misoperation caused by interference, thereby greatly improving the stability of the equipment.
In some embodiments, as shown in FIG. 2, when Io+.IS IS not satisfied, the method further comprises:
judging whether the MCU equipment is in a protection state or not;
if not, executing the step S50;
if the current value is in the protection state, judging whether the current value satisfies Io < IR, wherein IR is a recovery current value;
if yes, the PWM generator is recovered, and the step S50 is executed;
if not, the step S50 is directly performed.
It should be noted that, once the device is in the output overcurrent protection wave-sealing state, the MCU will further determine whether the output current Io is smaller than the recovery current value IR, if the output current Io is smaller than the recovery current value IR, the device will immediately resume PWM wave-sending, and at the same time clear the slow protection period count value N, at this time, the device resumes the normal working state again until the next protection action.
It should be noted that, here, the setting of the current value IR is recovered, under the condition that a capacitive load or a short circuit is suddenly added when similar output voltage is already established, the instantaneous current can be very large and far exceeds the set protection threshold, at this time, the direct current power supply can be quickly protected, the PWM is blocked, the output current can be quickly reduced, the equipment is ensured not to be damaged by the instantaneous large current, when the output current is reduced to the recovered current value IR, the equipment resumes the PWM wave again, after the capacitor is fully charged, the current is reduced to the equipment safety range to continue to operate, or the equipment can continue to operate at the set current value Iset constant current, as shown in fig. 3 and 4, so that the equipment is ensured to continuously and stably operate under the working condition, and the equipment cannot be normally used due to the protection shutdown.
The embodiment realizes high-precision grading protection of the output current, gives consideration to the safety and stability of equipment operation, and simultaneously adds the recovery current IR, so that the equipment can still automatically and normally operate after overcurrent protection.
In some embodiments, the step S10: sampling to obtain an output current value Io of the power supply, wherein the output current value Io comprises:
the power supply output current is filtered by a filter capacitor and then sampled by a sampling resistor to obtain a sampling voltage value U1;
amplifying the sampling voltage value U1 by using an operational amplifier to obtain a voltage value U2;
the voltage value U2 enters an ADC sampling circuit through a differential circuit to obtain the output current value Io.
It should be noted that, in this embodiment, the filtering capacitor is used to filter the output current of the power supply, so as to filter the output voltage, so as to realize smaller ripple output, and the high-precision sampling resistor Rsense is used to sample the output current of the dc power supply to obtain a sampled voltage value U1, and then the high-speed operational amplifier amplifies the voltage value U1 to obtain a voltage value U2, and then the voltage value U2 is sent to the high-speed ADC through the differential circuit, so that the differential circuit can effectively avoid common-mode interference, and the sampled value is more stable and accurate. The voltage signal U2 is subjected to analog-to-digital conversion in the ADC to obtain a digital quantity, and the digital quantity is transmitted to the MCU, and then the accurate output current value Io is obtained after operations such as calibration, conversion and the like. The current sampling precision can reach several ten thousandths, even higher, and meanwhile, the anti-interference capability is also very strong due to the sampling differential transmission, so that the precision and the reliability of the sampling value are further ensured.
The embodiment adopts a high-speed operational amplifier and MCU digital control mode, realizes high-speed protection and high-precision protection, and can effectively realize multi-stage and time-sharing protection after adding the algorithm logic, thereby ensuring the quick protection in high impact current and normal work in low impact current without error protection. Meanwhile, the situation similar to the situation of sudden capacitive load or short circuit is considered in algorithm, the setting of the recovery current IR is added, so that the quick protection can be realized, equipment is not damaged, the equipment is not stopped under the working condition, the normal work is still ensured, and the normal running of the user test is ensured.
As shown in fig. 5 to 6, a second embodiment of the present invention discloses an overcurrent protection apparatus, the apparatus includes a power supply 10, a current acquisition circuit 20, an MCU device 30, and a PWM generator 40, the power supply 10 is connected to the MCU device 30 through the current acquisition circuit 20, and the MCU device 30 is connected to the power supply 10 through the PWM generator 40;
wherein, the MCU device 30 IS provided with a slow protection threshold IS, a fast protection threshold IF and a slow protection cycle number a, and the MCU device includes:
an acquisition module 31 for acquiring an output current value Io of the power supply;
a first judging module 32 for judging whether the Io is greater than or equal to IF;
a second judging module 33, configured to judge whether Io IS greater than or equal to IS satisfied when the output result of the first judging module 32 IS no;
a third judging module 34, configured to, when the output result of the second judging module 33 is yes, make n=n+1, and judge whether N is greater than or equal to a, where N represents a slow protection period count value;
a first determining module 35, configured to execute a protection action when the output results of the first judging module 31 and the third judging module 34 are yes, and block the PWM generator 40; and is configured to control zero clearing of the N value when the output result of the second judging module 33 is no.
It should be noted that, in this embodiment, the output current of the power supply IS obtained by obtaining the current through the current, and IS input into the MCU for logic operation, and the MCU device IS provided with a fast protection threshold IF, a slow protection threshold IS, a recovery value IR, and a slow protection recovery cycle number a; comparing the value of the Io with a fast protection threshold IF and a slow protection threshold IS which are set previously, and IF the value of the Io IS larger than the fast protection threshold, immediately blocking the PWM generator by the MCU to realize wave-sealing protection; IF the Io IS between IS and IF, the MCU will not immediately block the PWM generator, but it will need to detect that the Io IS between IS and IF for a continuous a switching period to block the PWM generator, and the protection will be blocked.
In some embodiments, the MCU device further has a recovery current value IR, and the MCU device further includes:
a fourth judging module, configured to judge whether the MCU device is in a protection state;
the second determining module is used for controlling the N value to be cleared when the output result of the fourth judging module is NO;
a fifth judging module, configured to judge whether Io < IR is satisfied or not when the output result of the fourth judging module is yes, where IR is a recovery current value;
the third determining module is used for recovering the PWM generator and controlling the N value to be cleared when the output result of the fifth judging module is yes; and the control module is used for controlling the N value to be cleared when the output result of the fifth judging module is NO.
It should be noted that, after the protection of the sealing wave occurs, the current will often decrease rapidly, when the current decreases to the safety threshold (recovery value) IR, the MCU will recover the PWM generator and re-emit the wave, at this time, if the overcurrent phenomenon has disappeared (for example, in the case of suddenly adding the capacitive load, after the capacitor is fully charged, the overcurrent phenomenon disappears), the device will normally operate in the state of sealing the front, at this time, if the load at the output end is still a low-resistance load or a short circuit, the device will operate at the constant current value Iset set by the user. The phenomenon can not cause the equipment to be protected and stopped after the phenomenon of overcurrent and the like occurs, so that the equipment can not normally output.
In some embodiments, the current acquisition circuit includes a capacitor 21, a sampling resistor 22, an operational amplifier 23, a differential circuit 24, and an ADC sampling circuit 25, wherein:
the capacitor 21 is connected in parallel with two ends of the power supply 10, two ends of the capacitor 21 are connected in parallel with a load 50, a sampling resistor 22 is connected in series between the capacitor 21 and the load 50, the sampling resistor 22 is connected with a differential circuit 24 through an operational amplifier 23, and the differential circuit 24 is connected with the MCU device 30 through an ADC sampling circuit 25.
It should be noted that, in this embodiment, the output current of the dc power supply is sampled with high precision by using the high-precision and low-temperature drift sampling resistor Rsense to obtain a sampled voltage value U1, then the voltage value U1 is amplified by using the high-speed op-amp to obtain a voltage value U2, and then the U2 is sent to the high-speed ADC through the differential circuit, so that the differential circuit can effectively avoid common-mode interference, and the sampled value is more stable and accurate. The voltage signal U2 is subjected to analog-to-digital conversion in the ADC to obtain a digital quantity, and the digital quantity is transmitted to the MCU, and then the accurate output current value Io is obtained after operations such as calibration, conversion and the like.
A third embodiment of the present invention discloses an apparatus comprising a memory, a processor; wherein the processor runs a program corresponding to the executable program code by reading the executable program code stored in the memory for implementing the method as described above.
It should be noted that the logic and/or steps represented in the flowcharts or otherwise described herein, for example, may be considered as a ordered listing of executable instructions for implementing logical functions, and may be embodied in any computer-readable medium for use by or in connection with an instruction execution system, apparatus, or device, such as a computer-based system, processor-containing system, or other system that can fetch the instructions from the instruction execution system, apparatus, or device and execute the instructions. For the purposes of this description, a "computer-readable medium" can be any means that can contain, store, communicate, propagate, or transport the program for use by or in connection with the instruction execution system, apparatus, or device. More specific examples (a non-exhaustive list) of the computer-readable medium would include the following: an electrical connection (electronic device) having one or more wires, a portable computer diskette (magnetic device), a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disc read-only memory (CDROM). In addition, the computer readable medium may even be paper or other suitable medium on which the program is printed, as the program may be electronically captured, via, for instance, optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner, if necessary, and then stored in a computer memory.
It is to be understood that portions of the present invention may be implemented in hardware, software, firmware, or a combination thereof. In the above-described embodiments, the various steps or methods may be implemented in software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented in hardware, as in another embodiment, may be implemented using any one or combination of the following techniques, as is well known in the art: discrete logic circuits having logic gates for implementing logic functions on data signals, application specific integrated circuits having suitable combinational logic gates, programmable Gate Arrays (PGAs), field Programmable Gate Arrays (FPGAs), and the like.
In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
Furthermore, the terms "first," "second," and the like, are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically defined otherwise.
While embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and not to be construed as limiting the invention, and that variations, modifications, alternatives and variations may be made to the above embodiments by one of ordinary skill in the art within the scope of the invention.
Claims (3)
1. An over-current protection method for execution on an MCU device, the method comprising:
s10, sampling to obtain an output current value Io of the power supply, wherein the output current value Io comprises:
the power supply output current is filtered by a filter capacitor and then sampled by a sampling resistor to obtain a sampling voltage value U1;
amplifying the sampling voltage value U1 by using an operational amplifier to obtain a voltage value U2;
the voltage value U2 enters an ADC sampling circuit through a differential circuit to obtain the output current value Io;
s20, judging whether the Io is more than or equal to the IF, IF the IF is a rapid protection threshold, executing the step S60 IF the IF is the rapid protection threshold, and otherwise executing the step S30;
s30, judging whether the Io IS more than or equal to IS, if the IS IS a slow protection threshold, executing a step S40 if the IS IS a slow protection threshold, and if the IS IS not a slow protection threshold, executing a step S50;
s40, enabling N=N+1, judging whether N is more than or equal to a, wherein N represents a slow protection period count value, a represents a slow protection period number, if yes, executing a step S60, and if not, executing a step S10;
s50, resetting the N value, and then executing the step S10;
s60, executing a protection action, blocking the PWM generator, and then executing a step S10;
when the Io IS not more than IS, the method further comprises:
judging whether the MCU equipment is in a protection state or not;
if not, executing the step S50;
if the current value is in the protection state, judging whether the current value satisfies Io < IR, wherein IR is a recovery current value;
if yes, the PWM generator is recovered, and the step S50 is executed;
if not, the step S50 is directly performed.
2. The overcurrent protection device is characterized by comprising a power supply, a current acquisition circuit, MCU equipment and a PWM generator, wherein the power supply is connected with the MCU equipment through the current acquisition circuit, and the MCU equipment is connected with the power supply through the PWM generator; the current acquisition circuit comprises a capacitor, a sampling resistor, an operational amplifier, a differential circuit and an ADC sampling circuit, wherein the capacitor is connected in parallel with two ends of the power supply, two ends of the capacitor are connected with a load in parallel, the sampling resistor is connected in series between the capacitor and the load, the sampling resistor is connected with the differential circuit through the operational amplifier, and the differential circuit is connected with the MCU equipment through the ADC sampling circuit;
wherein, be provided with slow protection threshold IS, fast protection threshold IF and slow protection cycle number a in the MCU equipment, the MCU equipment includes:
the acquisition module is used for acquiring an output current value Io of the power supply;
the first judging module is used for judging whether the Io is more than or equal to the IF;
the second judging module IS used for judging whether the Io IS more than or equal to IS or not when the output result of the first judging module IS NO;
the third judging module is used for enabling N=N+1 and judging whether N is more than or equal to a or not when the output result of the second judging module is yes, wherein N represents a slow protection period count value;
the first determining module is used for executing a protection action and blocking the PWM generator when the output result of the first judging module and the third judging module is yes; and the control module is used for controlling the N value to be cleared when the output result of the second judging module is NO;
the MCU equipment is also provided with a recovery current value IR, and the MCU equipment further comprises:
a fourth judging module, configured to judge whether the MCU device is in a protection state;
the second determining module is used for controlling the N value to be cleared when the output result of the fourth judging module is NO;
a fifth judging module, configured to judge whether Io < IR is satisfied or not when the output result of the fourth judging module is yes, where IR is a recovery current value;
the third determining module is used for recovering the PWM generator and controlling the N value to be cleared when the output result of the fifth judging module is yes; and the control module is used for controlling the N value to be cleared when the output result of the fifth judging module is NO.
3. An apparatus comprising a memory, a processor; wherein the processor runs a program corresponding to the executable program code by reading the executable program code stored in the memory for implementing the method of claim 1.
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