CN108599098B - Overcurrent protection device, PFC circuit, air conditioner and overcurrent protection method of air conditioner - Google Patents
Overcurrent protection device, PFC circuit, air conditioner and overcurrent protection method of air conditioner Download PDFInfo
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- CN108599098B CN108599098B CN201810564709.2A CN201810564709A CN108599098B CN 108599098 B CN108599098 B CN 108599098B CN 201810564709 A CN201810564709 A CN 201810564709A CN 108599098 B CN108599098 B CN 108599098B
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- 238000000034 method Methods 0.000 title claims abstract description 26
- 238000001514 detection method Methods 0.000 claims abstract description 33
- 238000005070 sampling Methods 0.000 claims abstract description 27
- 238000001914 filtration Methods 0.000 claims description 23
- 238000011282 treatment Methods 0.000 claims description 7
- 230000001960 triggered effect Effects 0.000 claims description 5
- 238000012545 processing Methods 0.000 abstract description 12
- 230000000694 effects Effects 0.000 abstract description 4
- 239000003990 capacitor Substances 0.000 description 6
- 230000008569 process Effects 0.000 description 6
- 238000010586 diagram Methods 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 4
- 230000008859 change Effects 0.000 description 3
- 238000004146 energy storage Methods 0.000 description 3
- 238000006243 chemical reaction Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000005347 demagnetization Effects 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
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- 230000004044 response Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
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Classifications
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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
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/42—Circuits or arrangements for compensating for or adjusting power factor in converters or inverters
- H02M1/4208—Arrangements for improving power factor of AC input
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
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- Power Engineering (AREA)
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- Dc-Dc Converters (AREA)
Abstract
The invention discloses an overcurrent protection device, a PFC circuit, an air conditioner and an overcurrent protection method thereof, wherein the device comprises the following components: a detection circuit (102) and a cut-off circuit (104); the detection circuit (102) is used for detecting whether a set overcurrent phenomenon occurs in the PFC circuit to be protected, and if the overcurrent phenomenon occurs in the PFC circuit, a set trigger signal is sent to the cut-off circuit (104); the cut-off circuit (104) is used for receiving the trigger signal and cutting off the power supply of the driving signal of the PFC circuit based on the trigger signal so as to interrupt the load operation of the PFC circuit. The scheme of the invention can solve the problem of poor timeliness of the overcurrent protection of the PFC circuit caused by a certain time required by processing and comparing and calculating the sampling signals in the software control of the overcurrent protection of the PFC circuit in the prior art, and achieves the effect of improving the timeliness of the overcurrent protection of the PFC circuit.
Description
Technical Field
The invention belongs to the technical field of PFC overcurrent protection, and particularly relates to an overcurrent protection device, a PFC circuit, an air conditioner and an overcurrent protection method thereof, in particular to an air conditioner PFC hardware protection circuit, a PFC circuit with the hardware protection circuit, an air conditioner with the PFC circuit and an overcurrent protection method of the air conditioner.
Background
In recent years, variable frequency air conditioners and other variable frequency high-power machines adopt a PFC (power factor correction) circuit to improve the conversion efficiency of a power supply. In order to protect the post-stage load such as a compressor or the overcurrent damage of a power device, normally, the control of PFC overcurrent protection adopts software control, and the working principle is as follows: sampling loop current of the PFC circuit; transmitting the sampled signals to a main chip for analog-to-digital conversion and judging the current; judging whether the current exceeds a preset protection threshold value or not through a program; if the threshold value is exceeded, the main chip stops the driving signal of the PFC circuit and the subsequent load so as to stop the operation of the load. The software processing mode of PFC overcurrent protection is simple in operation, but a certain time is needed because a program needs to process and compare and calculate sampling signals, if the delay time is long, the instantaneous overcurrent can burn IGBT and the like in a PFC circuit, and meanwhile, the risks of damage of a power device and demagnetization failure of a compressor exist.
Disclosure of Invention
The invention aims to overcome the defects, and provides an overcurrent protection device, a PFC circuit, an air conditioner and an overcurrent protection method thereof, which are used for solving the problem that the timeliness of the overcurrent protection of the PFC circuit is poor because the PFC circuit is burnt out due to overcurrent when delay time is long because a program needs a certain time for processing and comparing and calculating sampling signals in software control of the overcurrent protection of the PFC circuit in the prior art, and achieving the effect of improving the timeliness of the overcurrent protection of the PFC circuit.
The invention provides an overcurrent protection device, comprising: a detection circuit and a cut-off circuit; the detection circuit is used for detecting whether a set overcurrent phenomenon occurs in the PFC circuit to be protected, and if the overcurrent phenomenon occurs in the PFC circuit, a set trigger signal is sent to the cut-off circuit; and the cut-off circuit is used for receiving the trigger signal and cutting off the power supply of the driving signal of the PFC circuit based on the trigger signal so as to interrupt the load operation of the PFC circuit.
Optionally, the cut-off circuit includes: a first switching tube and a second switching tube; the first switching tube and the second switching tube are connected in series between a power supply receiving end of a power supply of a driving signal of the PFC circuit in the cut-off circuit and a signal receiving end of the triggering signal in the cut-off circuit; wherein, the power of the driving signal of PFC circuit includes: at least one of a first power supply source for supplying power to a driving circuit of the PFC circuit and a second power supply source for supplying power to a switching tube of the PFC circuit synchronously; the first switch tube and the second switch tube are used for controlling the on-off of the first power supply or the second power supply.
Optionally, the cut-off circuit further includes: a shielding module; the shielding module is connected with the first switching tube in parallel and is used for shielding the on-off control function of the first switching tube and the second switching tube on the first power supply or the second power supply.
Optionally, the cut-off circuit further includes: at least one of a current limiting module and a filtering module; the current limiting module is used for carrying out current limiting treatment on a circuit where the first switching tube and/or the second switching tube are/is located; the filtering module is used for filtering the circuit where the first switching tube and/or the second switching tube are/is located.
Optionally, the detection circuit includes: the sampling module and the voltage comparison module; the sampling module is used for sampling PFC voltage of the PFC circuit and sending the PFC voltage to the voltage comparison module; the voltage comparison module is used for receiving the PFC voltage and comparing the PFC voltage with a set voltage; if the PFC voltage is greater than or equal to the set voltage, determining that the PFC circuit generates the overcurrent phenomenon, and sending the trigger signal to a signal receiving end of the cut-off circuit.
Optionally, the voltage comparison module includes: a voltage comparator and a voltage dividing resistor; the voltage dividing resistor is connected to the non-inverting input end of the voltage comparator and is used for setting the set voltage through resistor voltage division; an inverting input of the voltage comparator for receiving the PFC voltage; and the output end of the voltage comparator is used for outputting the trigger signal.
In accordance with another aspect of the present invention, in response to the foregoing apparatus, a PFC circuit is provided, including: the above-described overcurrent protection device.
In accordance with another aspect of the present invention, there is provided an air conditioner including: the PFC circuit described above.
In accordance with another aspect of the present invention, in response to the foregoing air conditioner, an over-current protection method for an air conditioner is provided, including: comprising the following steps: detecting whether a PFC circuit to be protected generates a set overcurrent phenomenon or not through a detection circuit, and if the PFC circuit generates the overcurrent phenomenon, sending a set trigger signal to a cut-off circuit; and receiving the trigger signal through a cut-off circuit, and cutting off the power supply of the driving signal of the PFC circuit based on the trigger signal so as to interrupt the load operation of the PFC circuit.
Optionally, the power supply of the driving signal of the PFC circuit includes: at least one of a first power supply source for supplying power to a driving circuit of the PFC circuit and a second power supply source for supplying power to a switching tube of the PFC circuit synchronously; cutting off, by a cut-off circuit, a power supply of a driving signal of the PFC circuit based on the trigger signal, including: and controlling the on-off of the first power supply or the second power supply through the first switching tube and the second switching tube.
Optionally, the switching-off circuit switches off the power supply of the driving signal of the PFC circuit based on the trigger signal, and further includes: the on-off control function of the first switching tube and the second switching tube on the first power supply or the second power supply is shielded through a shielding module; and/or, performing current limiting treatment on the circuit where the first switching tube and/or the second switching tube are/is located through a current limiting module; and/or filtering the line where the first switching tube and/or the second switching tube are/is located through a filtering module.
Optionally, detecting, by the detection circuit, whether a set overcurrent phenomenon occurs in the PFC circuit to be protected includes: the PFC voltage of the PFC circuit is sampled through a sampling module and is sent to a voltage comparison module; receiving the PFC voltage through the voltage comparison module, and comparing the PFC voltage with a set voltage; if the PFC voltage is greater than or equal to the set voltage, determining that the PFC circuit generates the overcurrent phenomenon, and sending the trigger signal to a signal receiving end of the cut-off circuit.
According to the scheme, the load is protected by directly cutting off the power supply of the PFC driving circuit based on innovation on the protection of the PFC circuit, so that the problem of equipment failure caused by untimely control when the PFC power circuit is in overcurrent can be effectively solved.
Furthermore, according to the scheme of the invention, the power supply of the PFC driving circuit is directly cut off at the moment of detecting overcurrent on hardware, so that the purpose of interrupting load operation is achieved, the cutting-off timeliness is good, and the reliability of the controller is improved.
Furthermore, the scheme of the invention provides a hardware protection circuit and a scheme aiming at PFC overcurrent protection based on the hardware logic circuit, so that the PFC circuit can be timely and effectively protected, equipment faults are prevented, and the stability of variable-frequency air conditioner equipment is improved.
Furthermore, the scheme of the invention directly cuts off the circuit of the PFC switch tube power supply and the load driving signal through the detection circuit, realizes the control scheme of PFC overcurrent protection, and has good timeliness and high reliability.
Therefore, the scheme of the invention directly cuts off the power supply of the PFC driving circuit at the moment of detecting the overcurrent on hardware, achieves the aim of interrupting the load operation, and solves the problem of poor timeliness of the overcurrent protection of the PFC circuit caused by a certain time required by a program for processing and comparing and calculating the sampling signal in the software control of the overcurrent protection of the PFC circuit in the prior art, thereby overcoming the defects of poor timeliness, low reliability and poor safety in the prior art and realizing the beneficial effects of good timeliness, high reliability and good safety.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
The technical scheme of the invention is further described in detail through the drawings and the embodiments.
Drawings
FIG. 1 is a schematic diagram of an embodiment of an overcurrent protection device according to the present invention;
fig. 2 is a schematic structural diagram of an embodiment of PFC topology in the overcurrent protection device according to the present invention;
FIG. 3 shows a voltage comparison circuit in the over-current protection device of the present invention;
FIG. 4 shows a PFC driving circuit in an over-current protection device according to the present invention;
FIG. 5 shows a power cut-off circuit in the overcurrent protection device of the invention;
fig. 6 is a schematic diagram of an overcurrent protection flow of an embodiment of the PFC circuit according to the present invention;
fig. 7 is a schematic diagram of an overcurrent protection flow of another embodiment of the PFC circuit according to the present invention
FIG. 8 is a flow chart illustrating an embodiment of an over-current protection method of an air conditioner according to the present invention;
fig. 9 is a flowchart illustrating an embodiment of detecting whether a set overcurrent phenomenon occurs in a PFC circuit to be protected in an overcurrent protection method of an air conditioner according to the present invention.
In the embodiment of the present invention, reference numerals are as follows, in combination with the accompanying drawings:
102-a detection circuit; 104-cutting off the circuit.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments of the present invention and corresponding drawings. It will be apparent that the described embodiments are only some, but not all, embodiments of the invention. 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.
According to an embodiment of the present invention, there is provided an overcurrent protection device, as shown in fig. 1, which is a schematic flow chart of an embodiment of the method of the present invention. The overcurrent protection device may include: a detection circuit 102 and a cut-off circuit 104.
In an alternative example, the detection circuit 102 may be configured to detect whether a set overcurrent occurs in the PFC circuit to be protected, and if the PFC circuit has the overcurrent, send a set trigger signal to the shutdown circuit 104, which may be referred to as examples shown in fig. 2 and 3.
Optionally, the detection circuit 102 may include: a sampling module and a voltage comparison module.
In an alternative specific example, the sampling module may be configured to sample a PFC voltage of the PFC circuit and send the PFC voltage to the voltage comparison module.
For example: as shown in fig. 2, PFC voltage collected by sampling resistor R1 is supplied to a voltage comparator (e.g., comparator U1-a shown in fig. 3) at the rear to determine whether or not an overcurrent is acting.
In an alternative specific example, the voltage comparison module may be configured to receive the PFC voltage and compare the PFC voltage with a set voltage; if the PFC voltage is greater than or equal to the set voltage, it is determined that the PFC circuit generates the over-current phenomenon, and the trigger signal is sent to a signal receiving end of the cut-off circuit 104.
Therefore, the PFC voltage of the PFC circuit is sampled through the sampling module and is sent to the voltage comparison module, the PFC voltage is compared with the set voltage through the voltage comparison module, and the phenomenon that the PFC circuit is over-current is determined when the PFC voltage is greater than or equal to the set voltage, so that the circuit is triggered and cut off, sampling, comparison and triggering are realized through hardware, the operation reliability is high, and the operation timeliness is good.
More optionally, the voltage comparison module may include: a voltage comparator and a voltage dividing resistor.
In a more alternative specific example, the voltage dividing resistor is connected to the non-inverting input terminal of the voltage comparator, and may be used to set the set voltage by dividing the voltage through the resistor.
In a more alternative specific example, an inverting input of the voltage comparator may be used to receive the PFC voltage. The output end of the voltage comparator can be used for outputting the trigger signal.
For example: as shown in fig. 3, the current limit point is set by a resistor voltage division (e.g., by resistor R7 and resistor R8), and when the I-S signal change is detected, if the current limit point is exceeded, a trigger signal pfc_a is output to the cut-off circuit.
Therefore, the setting voltage is set in a resistor voltage dividing mode according to the requirement, and the setting mode is flexible and simple; the voltage comparator is used for comparing the voltages and sending the trigger signal, and the processing timeliness and the reliability are good.
In an alternative example, the cut-off circuit 104 may be configured to receive the trigger signal and cut off the power supply of the driving signal of the PFC circuit based on the trigger signal, so as to interrupt the load operation of the PFC circuit, which may be referred to as an example shown in fig. 5.
For example: in consideration of the fact that the hardware logic circuit is high in processing speed, innovation is carried out on PFC circuit protection, loads are protected by directly cutting off the power supply of the PFC driving circuit, the PFC circuit can be effectively protected, equipment faults are prevented, and the stability of the variable-frequency air conditioner is improved. Specifically, the power supply of the PFC driving circuit is directly cut off at the moment of overcurrent detection on hardware, so that the purpose of interrupting load operation is achieved, the reliability of a controller can be improved, and the problem of equipment failure caused by untimely control when the PFC power circuit is in overcurrent can be effectively solved.
For example: the control scheme of PFC overcurrent protection can be realized by directly cutting off the power supply of the PFC switch tube and a circuit of a load driving signal through a detection circuit. For example: the PFC drive signal may be turned off, or the drive signal of the load may be turned off.
Therefore, when the detection circuit detects that the PFC circuit to be protected has an overcurrent phenomenon, the cut-off circuit is triggered, so that the cut-off circuit directly cuts off the power supply of the driving signal of the PFC circuit, and the detection and the cut-off are realized through hardware, so that the timeliness is good, and the reliability is high.
Optionally, the cut-off circuit 104 may include: a first switching transistor (e.g., transistor Q3 shown in fig. 5) and a second switching transistor (e.g., transistor Q4 shown in fig. 5). The first switching tube and the second switching tube are connected in series between a power supply receiving end of a power supply of the driving signal of the PFC circuit in the cut-off circuit 104 and a signal receiving end of the trigger signal in the cut-off circuit 104.
The power supply of the driving signal of the PFC circuit may include: at least one of a first power supply (e.g., VC 1) that may be used to power a driving circuit of the PFC circuit, and a second power supply (e.g., VC 2) that may be used to synchronously power a switching tube of the PFC circuit.
For example: as shown in fig. 4, VC2 and VC1 in the driving circuit are a PFC switching tube power supply and a power supply of the amplifying optocoupler U2.
In an alternative specific example, the first switching tube and the second switching tube may be used to control on/off of the first power supply or the second power supply. For example: the first switching tube and the second switching tube may cut off the first power supply or the second power supply based on the trigger signal.
The switching-off circuit integrating the first switching tube and the second switching tube can only cut off one power supply. In the invention, two power supplies can be arranged, namely, when in use, one power supply can be cut off according to the needs, and if both power supplies are required to be cut off, two cut-off circuits are required.
For example: as shown in fig. 5, the cut-off circuit determines whether to cut off the power supply by pfc_a signal, controls the power supply to be cut off by two triodes, and may select to cut off VC2 or VC1. The cut-off of VC2 is to cut off the power supply of the PFC circuit switching tube directly, cut off the switching tube directly, cut-off of VC1 is to cut off the amplifying optocoupler power supply to make the driving signal of the switching tube directly interrupt.
For example: in fig. 5, Q3 is PNP, and Q4 is NPN, which are switching devices to form a cut-off circuit. In fig. 5, VC1 and VC2 are two alternatives, one alternative is to cut off VC1 (the power supply of the PFC driving signal may be 3.3V), and the other alternative is to cut off VC2 (VC 2 synchronously supplies power to the PFC switching tube may be 15V).
Therefore, different power supplies are controlled through the switching tube, the control timeliness is good, the reliability is high, and the timeliness and the reliability of the PFC circuit overcurrent protection are improved.
Optionally, the cut-off circuit 104 may further include: a shielding module (e.g., shielding resistor R66 shown in fig. 5).
The shielding module, which is parallel to the first switching tube (for example, the shielding resistor R66 is parallel to the collector and the emitter of the triode Q3), may be used to shield the on-off control function of the first switching tube and the second switching tube on the first power supply or the second power supply. For example: the shielding module is placed only in parallel with the switching tube Q3 and if installed shields the entire cut-off function, i.e. the cut-off circuit is not needed.
For example: the shielding module is connected with the first switching tube in parallel and can be used for controlling the on-off control function of the cut-off circuit of the first power supply or the second power supply when the on-off of the first power supply or the second power supply is not required.
For example: in fig. 5, the resistor R66 is a shield resistor, that is, can be installed without the need for the cutoff function, and normally is not installed.
Therefore, the switch tube which is not needed to be used is shielded by the shielding module, the processing mode is simple, convenient and reliable, and the flexibility is good.
Optionally, the cut-off circuit 104 may further include: at least one of a current limiting module and a filtering module.
In an alternative specific example, the current limiting module may be configured to perform a current limiting process on a line where the first switching tube and/or the second switching tube are located.
In an alternative specific example, the filtering module may be configured to perform filtering processing on a line where the first switching tube and/or the second switching tube are located.
For example: the rest of the resistors and capacitors in fig. 5 are current limiting and filtering effects.
Therefore, the current limiting module, the filtering module and the like are used for carrying out current limiting, filtering and other treatments on the circuit where the corresponding switching tube is located, so that the accuracy and the safety of overcurrent protection of the PFC circuit can be improved.
Through a large number of experiments, the technical scheme of the embodiment is adopted, and the load is protected for directly cutting off the power supply of the PFC driving circuit based on innovation in PFC circuit protection, so that the problem of equipment failure caused by untimely control when the PFC power circuit is in overcurrent can be effectively solved.
According to an embodiment of the present invention, there is also provided a PFC circuit corresponding to the overcurrent protection device. The PFC circuit may include: the above-described overcurrent protection device.
In an alternative embodiment, the scheme of the invention provides a hardware protection circuit and a scheme aiming at PFC overcurrent protection in consideration of the fact that the hardware logic circuit is high in processing speed, so that the PFC circuit can be effectively protected, equipment faults are prevented, and the stability of variable-frequency air conditioner equipment is improved.
In an alternative example, the scheme of the invention directly cuts off the power supply of the PFC driving circuit at the moment of detecting overcurrent on hardware, thereby achieving the purpose of interrupting load operation and improving the reliability of the controller; the problem of equipment failure caused by untimely control when the PFC power circuit is in overcurrent can be effectively solved.
In some schemes, innovation is performed on the current position of the detection IGBT in the PFC circuit, and the driving current of the IGBT is mainly detected to protect the switching device IGBT. The scheme of the invention is innovated in the protection of the PFC circuit, and protects the load by directly cutting off the power supply of the PFC driving circuit.
Optionally, according to the scheme of the invention, the control scheme of PFC overcurrent protection can be realized by directly cutting off the power supply of the PFC switch tube and the circuit of the load driving signal through the detection circuit.
In an alternative embodiment, the embodiment of the present invention may be described by taking the PFC drive signal cut off (in this example, the drive signal of the load is not represented, and the drive signal of the load is cut off by the same cut-off circuit).
In the software control of some PFC protection schemes, an overcurrent signal is mostly detected firstly and then sent to a main chip, the main chip turns off a PFC circuit and a post-stage load by judging whether a driving signal is really sent out after overcurrent, and the method possibly has a certain delay phenomenon in time; meanwhile, whether error protection and the like are judged, certain delay exists, and if the delay time is long, the switching tube is possibly damaged by high current instantaneously; some hardware schemes also turn off the switching tube and the load directly, and the time is faster than that of software, but the switching tube and the load are also turned off by signals, so that a certain fault risk exists.
For example: the main chip can include: setting an upper limit value of the PFC circuit current according to the load demand on software, and judging whether overcurrent occurs or not through the software; for example, the load is a compressor, the upper limit current is set according to the demagnetization protection current point of the compressor.
For example: judging whether the error protection is carried out or not, comprising: the software directly detects the current of the PFC circuit, but a certain time is required for the program to process and compare the adopted signals, which causes time delay.
The circuit of the present invention provides a way to cut off the drive signal by directly cutting off the power supply through hardware, and the specific embodiment is shown in fig. 6 and 7.
Fig. 2 shows a topology of PFC (not limited to) with normal operation of the circuit, and the I-S signal changes when an over-current of the circuit is detected. The I-S signal is a PFC voltage collected by the sampling resistor R1, and is supplied to a voltage comparator (e.g., the comparator U1-a shown in fig. 3) at the rear to determine whether or not the current is flowing.
In fig. 2, the alternating current is rectified by a rectifier bridge Z1, an inductance L1 is an energy storage device, a capacitor C1 plays roles of energy storage and filtering, RV1 is a protective device piezoresistor, G1 is a switching device IGBT, D1 is a diode for unidirectional conduction, R1 is a sampling resistor of PFC current, C3 is an energy storage filter, and C2 and R2 are RC filters.
Fig. 3 shows a voltage comparison circuit, in which a current limit point is set by a resistor voltage division (e.g., by a resistor R7 and a resistor R8), and when a change in the I-S signal is detected, if the current limit point is exceeded, a trigger signal pfc_a is output to a cut-off circuit.
Wherein fig. 3 may be a general voltage comparison circuit. In fig. 3, C6 and C7 are filter capacitors, R5 is a pull-up resistor, R4 and R6 are current limiting resistors, U1 is a voltage comparator, R7 and R8 are voltage dividing resistors, and the resistance values of R7 and R8 can be adjusted according to the required voltage values.
Fig. 4 shows a driving circuit, in which an IC-DRIVER is a common software driving signal, and the driving circuit drives a switching tube by normally sending the driving signal through a main chip and converting the driving signal into a DRIVER driving signal through an amplifying circuit, in which VC2 and VC1 are a PFC switching tube power supply and an amplifying optocoupler U2 power supply.
Fig. 4 may be a PFC driving circuit, and the driving voltage collecting sections in fig. 3, fig. 4, fig. 5, and fig. 2 together form a PFC protection circuit. In fig. 4, U1 is a PFC driving optocoupler (for example, the PFC driving optocoupler may be replaced by a PFC driving chip without considering cost), and mainly functions to drive a switching tube, C8 and C9 are filter capacitors, Q2 is a triode driving optocoupler, diode D2 functions to prevent current reversal, R9 is a pull-down resistor of a power supply, and R10, R11 and R13 are current limiting resistors; the IC-DRIVER is a driving signal of the PFC circuit and is sent out by the main chip.
Fig. 5 shows a cut-off circuit for determining whether to cut off the power supply by pfc_a signal, and controlling the power supply cut-off by two transistors, and optionally cutting off VC2 or VC1. The cut-off of VC2 is to cut off the power supply of the PFC circuit switching tube directly, cut off the switching tube directly, cut-off of VC1 is to cut off the amplifying optocoupler power supply to make the driving signal of the switching tube directly interrupt.
For example: if only the VC1 power supply needs to be cut off, all the VC2 power supplies in the embodiment will not be shown, the cut-off circuit is composed of two switching tubes, and one cut-off circuit can cut off only 1 power supply.
Fig. 5 may be a hardware shutdown circuit of the present invention. In the prior art, the hardware protection circuit stops driving signals of the PFC circuit and the subsequent load for the main chip so as to stop the load from running, rather than stopping the operation by cutting off power supplies of the PFC driving signal and the load driving signal. In fig. 5, VC1 and VC2 are two alternatives, one alternative is to cut off VC1 (the power supply of the PFC driving signal may be 3.3V), and the other alternative is to cut off VC2 (VC 2 synchronously supplies power to the PFC switching tube may be 15V). In fig. 5, Q3 is PNP, Q4 is NPN, and the switching devices form a cut-off circuit, and the resistor R66 is a shielding resistor, that is, can be installed without the need for the cut-off function, and is normally unnecessary, and the rest of the resistor and capacitor have the functions of current limiting and filtering.
Since the processing and functions implemented by the circuit of the present embodiment substantially correspond to the embodiments, principles and examples of the apparatus shown in fig. 1 to 5, the description of the present embodiment is not exhaustive, and reference may be made to the related descriptions in the foregoing embodiments, which are not repeated herein.
Through a large number of experiments, the technical scheme of the invention is adopted, the power supply of the PFC driving circuit is directly cut off at the moment of detecting overcurrent on hardware, the purpose of interrupting load operation is achieved, the cutting-off timeliness is good, and the reliability of the controller is improved.
According to an embodiment of the present invention, there is also provided an air conditioner corresponding to the PFC circuit. The air conditioner may include: the PFC circuit described above.
Since the processing and the functions implemented by the air conditioner of the present embodiment basically correspond to the embodiments, principles and examples of the PFC circuit, the description of the present embodiment is not exhaustive, and reference may be made to the related description of the foregoing embodiment, which is not repeated herein.
Through a large number of experiments, the technical scheme of the invention is adopted, and the hardware protection circuit and scheme are provided for PFC overcurrent protection based on the hardware logic circuit, so that the PFC circuit can be timely and effectively protected, equipment faults are prevented, and the stability of the variable-frequency air conditioner equipment is improved.
According to an embodiment of the present invention, there is further provided an over-current protection method of an air conditioner corresponding to the air conditioner, as shown in fig. 8, which is a schematic flow chart of an embodiment of the method of the present invention. The overcurrent protection method of the air conditioner can comprise the following steps:
At step S110, the detection circuit 102 detects whether the PFC circuit to be protected has a set overcurrent, and if the PFC circuit has the overcurrent, sends a set trigger signal to the shutdown circuit 104, which can be seen in the examples shown in fig. 2 and 3.
Optionally, in combination with a flowchart of an embodiment of detecting whether the PFC circuit to be protected has the set overcurrent phenomenon in the overcurrent protection method of the air conditioner of the present invention shown in fig. 9, a specific process of detecting whether the PFC circuit to be protected has the set overcurrent phenomenon in step S110 by the detection circuit 102 may be further described.
Step S210, through a sampling module, the PFC voltage of the PFC circuit is sampled and sent to a voltage comparison module.
For example: as shown in fig. 2, PFC voltage collected by sampling resistor R1 is supplied to a voltage comparator (e.g., comparator U1-a shown in fig. 3) at the rear to determine whether or not an overcurrent is acting.
Step S220, receiving the PFC voltage through the voltage comparison module, and comparing the PFC voltage with a set voltage; if the PFC voltage is greater than or equal to the set voltage, it is determined that the PFC circuit generates the over-current phenomenon, and the trigger signal is sent to a signal receiving end of the cut-off circuit 104.
For example: as shown in fig. 3, the current limit point is set by a resistor voltage division (e.g., by resistor R7 and resistor R8), and when the I-S signal change is detected, if the current limit point is exceeded, a trigger signal pfc_a is output to the cut-off circuit.
Therefore, the PFC voltage of the PFC circuit is sampled through the sampling module and is sent to the voltage comparison module, the PFC voltage is compared with the set voltage through the voltage comparison module, and the phenomenon that the PFC circuit is over-current is determined when the PFC voltage is greater than or equal to the set voltage, so that the circuit is triggered and cut off, sampling, comparison and triggering are realized through hardware, the operation reliability is high, and the operation timeliness is good.
At step S120, by switching off the circuit 104, receiving the trigger signal, and switching off the power supply of the driving signal of the PFC circuit based on the trigger signal to interrupt the load operation of the PFC circuit, an example shown in fig. 5 can be seen.
For example: in consideration of the fact that the hardware logic circuit is high in processing speed, innovation is carried out on PFC circuit protection, loads are protected by directly cutting off the power supply of the PFC driving circuit, the PFC circuit can be effectively protected, equipment faults are prevented, and the stability of the variable-frequency air conditioner is improved. Specifically, the power supply of the PFC driving circuit is directly cut off at the moment of overcurrent detection on hardware, so that the purpose of interrupting load operation is achieved, the reliability of a controller can be improved, and the problem of equipment failure caused by untimely control when the PFC power circuit is in overcurrent can be effectively solved.
For example: the control scheme of PFC overcurrent protection can be realized by directly cutting off the power supply of the PFC switch tube and a circuit of a load driving signal through a detection circuit. For example: the PFC drive signal may be turned off, or the drive signal of the load may be turned off.
Therefore, when the detection circuit detects that the PFC circuit to be protected has an overcurrent phenomenon, the cut-off circuit is triggered, so that the cut-off circuit directly cuts off the power supply of the driving signal of the PFC circuit, and the detection and the cut-off are realized through hardware, so that the timeliness is good, and the reliability is high.
Optionally, the power supply of the driving signal of the PFC circuit may include: at least one of a first power supply (e.g., VC 1) that may be used to power a driving circuit of the PFC circuit, and a second power supply (e.g., VC 2) that may be used to synchronously power a switching tube of the PFC circuit.
For example: as shown in fig. 4, VC2 and VC1 in the driving circuit are a PFC switching tube power supply and a power supply of the amplifying optocoupler U2.
Optionally, the specific process of cutting off the power of the driving signal of the PFC circuit based on the trigger signal by the cutting-off circuit 104 in step S120 may include: and controlling the on-off of the first power supply or the second power supply through the first switching tube and the second switching tube. For example: the first switching tube and the second switching tube may cut off the first power supply or the second power supply based on the trigger signal.
For example: as shown in fig. 5, the cut-off circuit determines whether to cut off the power supply by pfc_a signal, controls the power supply to be cut off by two triodes, and may select to cut off VC2 or VC1. The cut-off of VC2 is to cut off the power supply of the PFC circuit switching tube directly, cut off the switching tube directly, cut-off of VC1 is to cut off the amplifying optocoupler power supply to make the driving signal of the switching tube directly interrupt.
For example: in fig. 5, Q3 is PNP, and Q4 is NPN, which are switching devices to form a cut-off circuit. In fig. 5, VC1 and VC2 are two alternatives, one alternative is to cut off VC1 (the power supply of the PFC driving signal may be 3.3V), and the other alternative is to cut off VC2 (VC 2 synchronously supplies power to the PFC switching tube may be 15V).
Therefore, different power supplies are controlled through the switching tube, the control timeliness is good, the reliability is high, and the timeliness and the reliability of the PFC circuit overcurrent protection are improved.
Optionally, turning on the cut-off circuit 104 in step S120, cutting off the power of the driving signal of the PFC circuit based on the trigger signal may further include at least one of the following cases.
First case: and the shielding module is used for shielding the on-off control function of the first switching tube and the second switching tube on the first power supply or the second power supply.
For example: the shielding module is connected with the first switching tube in parallel and can be used for controlling the on-off control function of the cut-off circuit of the first power supply or the second power supply when the on-off of the first power supply or the second power supply is not required.
For example: in fig. 5, the resistor R66 is a shield resistor, that is, can be installed without the need for the cutoff function, and normally is not installed.
Therefore, the switch tube which is not needed to be used is shielded by the shielding module, the processing mode is simple, convenient and reliable, and the flexibility is good.
Second case: and carrying out current limiting treatment on the circuit where the first switching tube and/or the second switching tube are/is located through a current limiting module.
Third scenario: and filtering the circuit where the first switching tube and/or the second switching tube are/is located through a filtering module.
For example: the rest of the resistors and capacitors in fig. 5 are current limiting and filtering effects.
Therefore, the current limiting module, the filtering module and the like are used for carrying out current limiting, filtering and other treatments on the circuit where the corresponding switching tube is located, so that the accuracy and the safety of overcurrent protection of the PFC circuit can be improved.
Since the processes and functions implemented by the method of the present embodiment substantially correspond to the embodiments, principles and examples of the air conditioner described above, the description of the present embodiment is not exhaustive, and reference may be made to the related descriptions of the foregoing embodiments, which are not repeated herein.
A large number of experiments prove that by adopting the technical scheme of the invention, the circuit for directly cutting off the PFC switch tube power supply and the load driving signal through the detection circuit, the control scheme of PFC overcurrent protection is realized, and the timeliness is good and the reliability is high.
In summary, it is readily understood by those skilled in the art that the above-described advantageous ways can be freely combined and superimposed without conflict.
The above description is only an example of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.
Claims (13)
1. An overcurrent protection device, comprising: a detection circuit (102) and a cut-off circuit (104); wherein,
The detection circuit (102) is used for detecting whether a set overcurrent phenomenon occurs in the PFC circuit to be protected, and if the overcurrent phenomenon occurs in the PFC circuit, a set trigger signal is sent to the cut-off circuit (104);
the cut-off circuit (104) is used for receiving the trigger signal and cutting off the power supply of the driving signal of the PFC circuit based on the trigger signal so as to interrupt the load operation of the PFC circuit;
The cut-off circuit (104) comprises: a first switching tube and a second switching tube;
The first switching tube and the second switching tube are connected in series between a power supply receiving end of a driving signal of the PFC circuit in the cut-off circuit (104) and a signal receiving end of the triggering signal in the cut-off circuit (104);
Wherein,
The power supply of the driving signal of the PFC circuit comprises: at least one of a first power supply source for supplying power to a driving circuit of the PFC circuit and a second power supply source for supplying power to a switching tube of the PFC circuit synchronously;
the first switching tube and the second switching tube are used for controlling the on-off of the first power supply or the second power supply;
When the detection circuit detects that the PFC circuit to be protected has an overcurrent phenomenon, the cut-off circuit is triggered, so that the cut-off circuit directly cuts off the power supply of the driving signal of the PFC circuit, and the detection and the cut-off are realized through hardware, so that timeliness is good.
2. The apparatus of claim 1, wherein the shut-off circuit (104) further comprises: a shielding module;
The shielding module is connected with the first switching tube in parallel and is used for shielding the on-off control function of the first switching tube and the second switching tube on the first power supply or the second power supply.
3. The apparatus according to claim 1 or 2, wherein the shut-off circuit (104) further comprises: at least one of a current limiting module and a filtering module; wherein,
The current limiting module is used for carrying out current limiting treatment on the circuit where the first switching tube and/or the second switching tube are/is located;
The filtering module is used for filtering the circuit where the first switching tube and/or the second switching tube are/is located.
4. The apparatus according to one of claims 1-2, wherein the detection circuit (102) comprises: the sampling module and the voltage comparison module; wherein,
The sampling module is used for sampling PFC voltage of the PFC circuit and sending the PFC voltage to the voltage comparison module;
The voltage comparison module is used for receiving the PFC voltage and comparing the PFC voltage with a set voltage; if the PFC voltage is greater than or equal to the set voltage, determining that the PFC circuit has the overcurrent phenomenon, and sending the trigger signal to a signal receiving end of the cut-off circuit (104).
5. A device according to claim 3, characterized in that the detection circuit (102) comprises: the sampling module and the voltage comparison module; wherein,
The sampling module is used for sampling PFC voltage of the PFC circuit and sending the PFC voltage to the voltage comparison module;
The voltage comparison module is used for receiving the PFC voltage and comparing the PFC voltage with a set voltage; if the PFC voltage is greater than or equal to the set voltage, determining that the PFC circuit has the overcurrent phenomenon, and sending the trigger signal to a signal receiving end of the cut-off circuit (104).
6. The apparatus of claim 4, wherein the voltage comparison module comprises: a voltage comparator and a voltage dividing resistor; wherein,
The voltage dividing resistor is connected to the non-inverting input end of the voltage comparator and is used for setting the set voltage through resistor voltage division;
An inverting input of the voltage comparator for receiving the PFC voltage; and the output end of the voltage comparator is used for outputting the trigger signal.
7. The apparatus of claim 5, wherein the voltage comparison module comprises: a voltage comparator and a voltage dividing resistor; wherein,
The voltage dividing resistor is connected to the non-inverting input end of the voltage comparator and is used for setting the set voltage through resistor voltage division;
An inverting input of the voltage comparator for receiving the PFC voltage; and the output end of the voltage comparator is used for outputting the trigger signal.
8. A PFC circuit, comprising: an overcurrent protection device as set forth in any one of claims 1-7.
9. An air conditioner, comprising: the PFC circuit of claim 8.
10. The overcurrent protection method of the air conditioner as set forth in claim 9, comprising:
detecting whether a PFC circuit to be protected generates a set overcurrent phenomenon or not through a detection circuit (102), and if the PFC circuit generates the overcurrent phenomenon, sending a set trigger signal to a cut-off circuit (104);
and receiving the trigger signal through a cut-off circuit (104), and cutting off the power supply of the driving signal of the PFC circuit based on the trigger signal so as to interrupt the load operation of the PFC circuit.
11. The method of claim 10, wherein the power supply of the driving signal of the PFC circuit comprises: at least one of a first power supply source for supplying power to a driving circuit of the PFC circuit and a second power supply source for supplying power to a switching tube of the PFC circuit synchronously;
By a cut-off circuit (104), cutting off power of a driving signal of the PFC circuit based on the trigger signal, comprising:
And controlling the on-off of the first power supply or the second power supply through the first switching tube and the second switching tube.
12. The method of claim 11, wherein turning off the power of the driving signal of the PFC circuit based on the trigger signal by the cut-off circuit (104), further comprising:
The on-off control function of the first switching tube and the second switching tube on the first power supply or the second power supply is shielded through a shielding module;
And/or the number of the groups of groups,
The current limiting module is used for carrying out current limiting treatment on the circuit where the first switching tube and/or the second switching tube are/is located;
And/or the number of the groups of groups,
And filtering the circuit where the first switching tube and/or the second switching tube are/is located through a filtering module.
13. The method according to one of claims 10 to 12, wherein detecting, by the detection circuit (102), whether a set overcurrent phenomenon occurs in the PFC circuit to be protected comprises:
the PFC voltage of the PFC circuit is sampled through a sampling module and is sent to a voltage comparison module;
Receiving the PFC voltage through the voltage comparison module, and comparing the PFC voltage with a set voltage; if the PFC voltage is greater than or equal to the set voltage, determining that the PFC circuit has the overcurrent phenomenon, and sending the trigger signal to a signal receiving end of the cut-off circuit (104).
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| CN112736839B (en) * | 2020-12-11 | 2023-01-10 | 苏州浪潮智能科技有限公司 | Overcurrent detection and protection method, system and medium |
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| JP6382059B2 (en) * | 2014-10-16 | 2018-08-29 | ローム株式会社 | Switching power supply circuit |
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