CN113422350A - Overcurrent protection circuit and air conditioning equipment - Google Patents
Overcurrent protection circuit and air conditioning equipment Download PDFInfo
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- CN113422350A CN113422350A CN202110741165.4A CN202110741165A CN113422350A CN 113422350 A CN113422350 A CN 113422350A CN 202110741165 A CN202110741165 A CN 202110741165A CN 113422350 A CN113422350 A CN 113422350A
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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
- H02H7/08—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 dynamo-electric motors
- H02H7/0833—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 dynamo-electric motors for electric motors with control arrangements
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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
- 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
- H02H7/08—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 dynamo-electric motors
- H02H7/085—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 dynamo-electric motors against excessive load
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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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- 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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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Emergency Protection Circuit Devices (AREA)
Abstract
The invention discloses an overcurrent protection circuit and air conditioning equipment. The overcurrent protection circuit is applied to an air conditioner control circuit. The air conditioner control circuit comprises a microprocessor and a power module. And the microprocessor is used for outputting a compressor control signal to the power module so as to drive the compressor to work. The overcurrent protection circuit comprises a sampling circuit and a comparison circuit. The sampling circuit is used for detecting the working current of the compressor in the power module. The comparison circuit is used for generating an overcurrent protection signal when the working current of the compressor is larger than a preset value, outputting the overcurrent protection signal to an interrupt signal receiving end of the microprocessor, and outputting the overcurrent protection signal to an overcurrent protection control end of the power module. The overcurrent protection circuit can realize the hardware turn-off function of software overcurrent by simultaneously outputting the overcurrent protection signal to an interrupt signal receiving end of the microprocessor and an overcurrent protection control end of the power module.
Description
Technical Field
The invention relates to the technical field of air conditioners, in particular to an overcurrent protection circuit and an air conditioning device with the same.
Background
Currently, in an air conditioner, a PFC (Power Factor Correction) Module and an IPM (Intelligent Power Module) Module of an air conditioner compressor are generally integrated together to form a two-in-one Power Module. In an integrated two-in-one power module, the protection signal pin is usually shared, so that the PFC module protection and the IPM module protection cannot be distinguished. However, in practical applications, the actual protection current difference between the PFC module protection and the IPM module protection is large. When the IPM module with low current triggers protection, there is a corresponding self-locking delay effect, thereby affecting the timeliness of protection of the PFC module with high current.
Disclosure of Invention
Based on the above problems, embodiments of the present invention provide an overcurrent protection circuit, which aims to solve the problem of timeliness of overcurrent protection of an existing power module integrated with a PFC module and an IPM module.
One embodiment of the invention provides an overcurrent protection circuit which is used for an air conditioner control circuit. The air conditioner control circuit comprises a microprocessor and a power module. And the microprocessor is used for outputting a compressor control signal to the power module so as to drive the compressor to work. The overcurrent protection circuit includes:
the sampling circuit is used for detecting the working current of the compressor in the power module;
and the comparison circuit is used for generating an overcurrent protection signal when the working current of the compressor is greater than a preset value, outputting the overcurrent protection signal to an interrupt signal receiving end of the microprocessor and outputting the overcurrent protection signal to an overcurrent protection control end of the power module.
In an embodiment, the microprocessor further includes an overcurrent control signal receiving terminal connected to the overcurrent protection control terminal of the power module.
In an embodiment, the overcurrent protection circuit further includes a first diode, a cathode of the first diode is connected to the output terminal of the comparison circuit, and an anode of the first diode is connected to the overcurrent protection control terminal of the power module and the overcurrent control signal receiving terminal of the microprocessor.
In one embodiment, the power module comprises an N-pole terminal, the sampling circuit comprises a sampling resistor, one end of the sampling resistor is connected with the N-pole terminal, and the other end of the sampling resistor is connected with a common voltage terminal.
In one embodiment, the comparison circuit includes:
a comparator having a non-inverting input and an inverting input;
and the resistance biasing circuit is used for pressurizing the voltage values at the two ends of the sampling resistor and then respectively transmitting the voltage values to the reverse input end and the non-reverse input end of the comparator.
In one embodiment, the resistive bias circuit includes:
one end of the first resistor is connected with the inverting input end of the comparator, and the other end of the first resistor is connected with one end of the sampling resistor, which is connected with the N-pole terminal;
one end of the second resistor is connected with the non-inverting input end of the comparator, and the other end of the second resistor is connected with the common voltage end;
one end of the third resistor is connected with the inverting input end of the comparator;
one end of the fourth resistor is connected with the non-inverting input end of the comparator, and the other end of the fourth resistor is connected to one end of the third resistor, which is opposite to the inverting input end of the comparator;
one end of the fifth resistor is connected with a direct-current voltage, and the other end of the fifth resistor is connected to a common terminal of the third resistor and the fourth resistor.
In one embodiment, the resistance values of the first to fourth resistors satisfy the following relationship: the value of R2/(R2+ R4) is greater than the value of R1/(R1+ R3), wherein R1 is the resistance value of the first resistor; r2 is the resistance of the second resistor; r3 is the resistance of the third resistor; r4 is the resistance value of the fourth resistor.
In an embodiment, the overcurrent protection circuit further includes a first delay circuit, one end of the first delay circuit is connected to the output end of the comparison circuit, and the other end of the first delay circuit is connected to the interrupt signal receiving end of the microprocessor;
and/or the overcurrent protection circuit further comprises a second delay circuit, one end of the second delay circuit is connected with the overcurrent control signal receiving end of the microprocessor, and the other end of the second delay circuit is connected with the overcurrent protection control end of the power module.
In an embodiment, the first delay circuit includes a sixth resistor and a first capacitor, one end of the sixth resistor is connected to the output end of the comparison circuit, and the other end of the sixth resistor is connected to the interrupt signal receiving end of the microprocessor; one end of the first capacitor is connected with an interrupt signal receiving end of the microprocessor, and the other end of the first capacitor is connected with a grounding end;
and/or the second delay circuit comprises a seventh resistor and a second capacitor, one end of the seventh resistor is connected with an overcurrent control signal receiving end of the microprocessor, and the other end of the seventh resistor is connected with an overcurrent protection control end of the power module; one end of the second capacitor is connected with an overcurrent control signal receiving end of the microprocessor, and the other end of the second capacitor is connected with a grounding end.
Another embodiment of the present invention further provides an air conditioning apparatus, including the overcurrent protection circuit according to any one of the above embodiments.
When the IPM module part in the power module generates overcurrent, the comparison circuit can simultaneously output the generated overcurrent protection signal to an interrupt signal receiving end of the microprocessor and an overcurrent protection control end of the power module. In one aspect, the power module may immediately shut down the output of the compressor drive signal when it receives the over-current protection signal. On the other hand, when the microprocessor receives the overcurrent protection signal, the microprocessor can confirm the fault type through the voltage value of the interrupt signal receiving end, so that the overcurrent of the PFC module or the overcurrent of the IPM module can be distinguished, and a judgment basis is provided for the fault processing.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a schematic circuit diagram of an overcurrent protection circuit according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a portion of the power module of FIG. 1;
fig. 3 is a schematic circuit diagram of an overcurrent protection circuit according to another embodiment of the present invention;
fig. 4 is a schematic diagram of a working flow of an overcurrent protection circuit according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of the delay time from when the software samples an over-current signal to when an over-current fault is issued to shut down the compressor drive after an over-current occurs in the over-current protection circuit;
fig. 6 is a schematic diagram of an interrupt signal generated after an overcurrent occurs and a shutdown waveform of a compressor output.
The reference numbers illustrate:
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that if directional indications (such as up, down, left, right, front, and back … …) are involved in the embodiment of the present invention, the directional indications are only used to explain the relative positional relationship between the components, the movement situation, and the like in a specific posture, and if the specific posture is changed, the directional indications are changed accordingly.
In addition, if there is a description of "first", "second", etc. in an embodiment of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, if the meaning of "and/or" and/or "appears throughout, the meaning includes three parallel schemes, for example," A and/or B "includes scheme A, or scheme B, or a scheme satisfying both schemes A and B. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present invention.
Referring to fig. 1, an embodiment of the invention provides an overcurrent protection circuit 100. The overcurrent protection circuit 100 is applied to an air conditioner control circuit 200. The air conditioner control circuit 200 includes a microprocessor 210 and a power module 220. The microprocessor 210 is configured to output a compressor control signal to the power module 220 to drive the compressor to operate. The over-current protection circuit 100 includes a sampling circuit 110 and a comparison circuit 120.
The sampling circuit 110 is used to detect the compressor operating current in the power module 220.
The comparison circuit 120 is configured to generate an overcurrent protection signal when the working current of the compressor is greater than a preset value, output the overcurrent protection signal to the interrupt signal receiving terminal INT of the microprocessor 210, and output the overcurrent protection signal to the overcurrent protection control terminal FO of the power module 220.
In the over-current protection circuit 100 provided in this embodiment, by setting the sampling circuit 110 to detect the compressor operating current in the power module 220 and setting the comparison circuit 120 to generate the over-current protection signal when the compressor operating current is greater than the preset value, when the IPM module portion in the power module 220 generates an over-current, the comparison circuit 120 can simultaneously output the generated over-current protection signal to the interrupt signal receiving terminal INT of the microprocessor 210 and the over-current protection control terminal FO of the power module 220. On one hand, when the power module 220 receives the over-current protection signal, it may immediately shut down the output of the compressor driving signal. On the other hand, when the microprocessor 210 receives the overcurrent protection signal, it may determine the type of the fault through the voltage value of the interrupt signal receiving terminal INT, so as to distinguish whether the PFC module is overcurrent or the IPM module is overcurrent, thereby providing a judgment basis for the fault processing.
In one embodiment, the microprocessor 210 further includes an over-current control signal receiving terminal IPM _ FO. The over-current control signal receiving terminal IPM _ FO is connected to the over-current protection control terminal FO of the power module 220. In a specific operation process, when an overcurrent occurs in the power module 220, the overcurrent protection control terminal FO in the power module 220 outputs a control signal to the overcurrent control signal receiving terminal IPM _ FO of the microprocessor 210. Specifically, in the present embodiment, the over-current protection control terminal FO of the power module 220 is active low. That is, when the overcurrent protection control terminal FO of the power module 220 is at a high level, the power module 220 operates normally; when the over-current protection control terminal FO of the power module 220 is at a low level, the power module 220 turns off the output.
Specifically, in the present embodiment, when the IPM module portion of the power module 220 generates an overcurrent, the interrupt signal receiving terminal INT of the microprocessor 210 receives a low signal, and the overcurrent control signal receiving terminal IPM _ FO of the microprocessor 210 also receives a low signal. When the PFC module of the power module 220 generates an overcurrent, the overcurrent protection control terminal FO of the power module 220 outputs a control signal to the overcurrent control signal receiving terminal IPM _ FO of the microprocessor 210. However, at this time, since the voltage signal at the output terminal of the comparison circuit 120 is still maintained at the high level, the interrupt signal receiving terminal INT of the microprocessor 210 receives the high level signal. As can be seen, the microprocessor 210 can determine whether the IPM module overcurrent or the PFC module overcurrent occurs according to the level conditions of the interrupt signal receiving terminal INT and the overcurrent control signal receiving terminal IPM _ FO.
In one embodiment, the over-current protection circuit 100 further includes a first diode D1. The cathode of the first diode D1 is connected to the output terminal of the comparison circuit 120, and the anode of the first diode D1 is connected to the overcurrent protection control terminal FO of the power module 220 and the overcurrent control signal receiving terminal IPM _ FO of the microprocessor 210. The first diode D1 functions as a unidirectional isolation. That is, when the compressor is normally operated, the operation current of the compressor does not exceed the preset value. At this time, the voltage signal at the output terminal of the comparison circuit 120 is a high level signal. At this time, even if the voltage signal of the over-current protection control terminal FO of the power module 220 is a low level signal, it does not affect the high level voltage signal at the output terminal of the comparison circuit 120 due to the unidirectional conduction characteristic of the first diode D1. And when the working current of the compressor exceeds the preset value due to the abnormal operation of the compressor, the output end of the comparison circuit 120 outputs a low-level voltage signal. At this time, due to the unidirectional conduction characteristic of the first diode D1, the over-current protection control terminal FO of the power module 220 is also pulled down to be a low-level voltage signal, so as to trigger the power module 220 to perform hardware protection, and further turn off the output of the power module 220. In this embodiment, the first diode D1 is selected to have a lower turn-on voltage drop. The high level of the interrupt signal satisfying the overcurrent trigger is within the high-low level trigger range of the microprocessor 210 after passing through the forward voltage drop of the first diode D1, and satisfies the high-low level detection range of the IPM _ FO receiving end of the overcurrent control signal.
Specifically, in this embodiment, the power module 220 includes N-pole terminals NU, NV, NW of the lower arm IGBT device. The sampling circuit 110 includes a sampling resistor R10. One end of the sampling resistor R10 is connected to the N-pole terminals NU, NV, NW. The other end of the sampling resistor R10 is connected to a common voltage terminal VSS. As shown in fig. 2, for a three-phase type IPM module, it generally includes a first IGBT device Q1, a second IGBT device Q2, a third IGBT device Q3, a fourth IGBT device Q4, a fifth IGBT device Q5, and a sixth IGBT device Q6. The first IGBT device Q1 and the fourth IGBT device Q4 form a first bridge arm, and a U-phase voltage is output to the compressor motor at the connecting point of the first bridge arm; the second IGBT device Q2 and the fifth IGBT device Q5 form a second bridge arm, and the connection point of the second bridge arm outputs a V-phase voltage to the compressor motor; the third IGBT device Q3 and the sixth IGBT device Q6 form a third bridge arm, and the connection point of the third bridge arm outputs W-phase voltage to the compressor motor. At this time, the first IGBT device Q1, the second IGBT device Q2, and the third IGBT device Q3 are referred to as upper arm IGBT devices; the fourth IGBT device Q4, the fifth IGBT device Q5, and the sixth IGBT device Q6 are referred to as lower arm IGBT devices. The drain of the fourth IGBT device Q4 is an N-pole terminal NU; a fifth IGBT device Q5 is an N-pole terminal NV; the sixth IGBT device Q6 is the N-pole terminal NW. That is, by connecting the sampling resistor R10 to the N-terminal NU, NV, NW of the fourth to sixth IGBT devices Q4-Q6, the sampling resistor R10 can sample the operating current of the compressor during operation and then compare the operating current with a preset current value through the comparison circuit 120.
Specifically, in one embodiment, the comparison circuit 120 includes a comparator U1A and a resistance bias circuit 121. The resistor bias circuit 121 is configured to pressurize the voltage value at the two ends of the sampling resistor R10 and transmit the pressurized voltage value to the inverting input terminal and the non-inverting input terminal of the comparator U1A, respectively. In this embodiment, the resistor bias circuit 121 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, and a fifth resistor R5.
The comparator U1A has a non-inverting input and an inverting input. When the voltage value of the non-inverting input terminal of the comparator U1A is greater than the voltage value of the inverting input terminal of the comparator U1A, the output terminal of the comparator U1A outputs a high level. When the voltage value of the non-inverting input terminal of the comparator U1A is less than the voltage value of the inverting input terminal of the comparator U1A, the output terminal of the comparator U1A outputs a low level.
One end of the first resistor R1 is connected with the inverting input terminal of the comparator U1A. The other end of the first resistor R1 is connected to one end of the sampling resistor R10, which is connected to the N-pole terminals NU, NV, NW.
One end of the second resistor R2 is connected with the non-inverting input end of the comparator U1A. The other end of the second resistor R2 is connected to the common voltage terminal VSS.
One end of the third resistor R3 is connected to the inverting input of the comparator U1A.
One end of the fourth resistor R4 is connected to the non-inverting input of the comparator U1A. The other end of the fourth resistor R4 is connected to one end of the third resistor R3 opposite to the inverting input terminal of the comparator U1A.
One end of the fifth resistor R5 is connected to a dc voltage. The other end of the fifth resistor R5 is connected to the common terminal of the third resistor R3 and the fourth resistor R4. In this embodiment, the dc voltage connected to one end of the fifth resistor R5 is +5V dc voltage.
In a specific working process, the first resistor R1 and the third resistor R3 form a first voltage bias circuit, so that a voltage value at one end of the current detection resistor R10 is output to the inverting input end of the comparator U1A after being pressurized; the second resistor R2 and the fourth resistor R4 form a second voltage bias circuit, so as to output the voltage value at the other end of the sampling resistor R10 to the non-inverting input terminal of the comparator U1A after being pressurized. At this time, the resistance values of the first to fourth resistors R1-R4 can be set according to actual needs, so that the voltage value of the non-inverting input terminal of the comparator U1A is greater than the voltage value of the inverting input terminal of the comparator U1A when the compressor is in normal operation; when the compressor works abnormally, the voltage value of the non-inverting input end of the comparator U1A is smaller than that of the inverting input end of the comparator U1A. Specifically, assuming that the voltage value of the common terminal of the third resistor R3 and the fourth resistor R4 is U1, the voltage value of the common voltage terminal VSS is 0, and the voltage value of the end of the sampling resistor R10 connected to the N-pole terminals NU, NV, NW is U2, the voltage value U + of the non-inverting input terminal and the voltage value U-of the inverting input terminal of the comparator U1A are respectively:
U+＝(R2*U1)/(R2+R4)；
U-＝(R1*(U1-U2))/(R1+R3)；
it can be seen that in one embodiment, the value of R2/(R2+ R4) should be greater than the value of R1/(R1+ R3). Because, when the voltage value U2 of the end of the sampling resistor R10 connected to the N-pole terminals NU, NV, NW is small (e.g., close to zero), the voltage value U-at the inverting input of the comparator U1A is approximately equal to (R1 × U1)/(R1+ R3). At this time, if the voltage value of the non-inverting input terminal of the comparator U1A is required to be greater than the voltage value of the inverting input terminal of the comparator U1A, the value of R2/(R2+ R4) should be greater than the value of R1/(R1+ R3). It is only satisfied that when the compressor is operating normally, the output terminal of the comparator U1A outputs a high level signal.
In this embodiment, the comparing circuit 120 further includes a third capacitor C3 and a fourth capacitor C4. One end of the third capacitor C3 is connected to the non-inverting input terminal of the comparator U1A, and the other end of the third capacitor C3 is grounded. One end of the fourth capacitor C4 is connected to the inverting input terminal of the comparator U1A, and the other end of the fourth capacitor C4 is grounded. The third capacitor C3 is used for filtering an interference signal between the non-inverting input terminal of the comparator U1A and the ground terminal; the fourth capacitor C4 is used to filter the interference signal between the inverting input terminal of the comparator U1A and the ground terminal. The comparison circuit 120 further includes a fifth capacitor C5, as needed. One end of the fifth capacitor C5 is connected to the non-inverting input terminal of the comparator U1A, and the other end of the fifth capacitor C5 is connected to the inverting input terminal of the comparator U1A. The fifth capacitor C5 is used to filter the interference signal between the non-inverting input terminal of the comparator U1A and the inverting input terminal of the comparator U1A.
It is understood that the comparator U1A may also include a power terminal and a ground terminal. In this embodiment, the power supply terminal of the comparator U1A is connected to +5V dc voltage, and the ground terminal of the comparator U1A is grounded.
The over-current protection circuit 100 may further include a pull-up resistor R9, as needed. One end of the pull-up resistor R9 is connected to the output terminal of the comparison circuit 120. The other end of the pull-up resistor R9 is connected with a DC voltage of + 5V.
It is understood that the over-current protection circuit 100 may further include a delay circuit, so as to delay the over-current protection signal outputted from the comparison circuit 120 for a certain time and then output the delayed over-current protection signal to the interrupt signal input end INT of the microprocessor circuit 210 and the over-current control signal receiving end IPM _ FO. Referring to fig. 3, another embodiment of the invention further provides an overcurrent protection circuit 100. Unlike the above embodiments, the overcurrent protection circuit 100 further includes a first delay circuit 130. One end of the first delay circuit 130 is connected to the output end of the comparison circuit 120. The other end of the first delay circuit 130 is connected to an interrupt signal receiving terminal INT of the microprocessor 210. By providing the first delay circuit 130, the over-current protection signal output by the comparison circuit 120 can be delayed for a certain time and then output to the interrupt signal receiving terminal INT of the microprocessor 210. The first delay circuit 130 is provided to avoid the false triggering phenomenon caused by the existence of the interference signal in the line.
In this embodiment, the first delay circuit 130 includes a sixth resistor R6 and a first capacitor C1.
One end of the sixth resistor R6 is connected to the output terminal of the comparison circuit 120. The other end of the sixth resistor R6 is connected to an interrupt signal receiving terminal INT of the microprocessor 210.
One end of the first capacitor C1 is connected to an interrupt signal receiving terminal INT of the microprocessor 210. The other end of the first capacitor C1 is connected to the ground GND.
In an actual working process, when the working current of the compressor is greater than a preset value, the comparison circuit 120 generates an overcurrent protection signal and outputs the overcurrent protection signal to the interrupt signal receiving terminal INT of the microprocessor 210. In this embodiment, the over-current protection signal is a low level signal. Since the voltage across the first capacitor C1 cannot change abruptly, when the output terminal of the comparison circuit 120 outputs a low level signal, the first capacitor C1 (the first capacitor C1 has been charged when the output terminal of the comparison circuit 120 is a high level signal) is discharged through the sixth resistor R6. After a certain time, the first capacitor C1 finishes discharging, so that the interrupt signal receiving terminal INT of the microprocessor 210 receives a low-level overcurrent protection signal. If there is a low level pulse signal (with a short signal duration) at the output terminal of the comparison circuit 120 due to the presence of the interference signal in the circuit, the first capacitor C1 may not be completely discharged within the pulse duration range of the interference signal, and therefore, the interrupt signal receiving terminal INT of the microprocessor 210 may not generate the false triggering phenomenon due to the presence of the interference signal.
In one embodiment, the over-current protection circuit 100 further includes a second delay circuit 140. One end of the second delay circuit 140 is connected to the overcurrent control signal receiving terminal IPM _ FO of the microprocessor 210, and the other end of the second delay circuit 140 is connected to the overcurrent protection control terminal FO of the power module 220. The second delay circuit 140 is provided to avoid the false triggering phenomenon caused by the existence of the interference signal in the line.
In this embodiment, the second delay circuit 140 includes a seventh resistor R7 and a second capacitor C2.
One end of the seventh resistor R7 is connected to the overcurrent control signal receiving terminal IPM _ FO of the microprocessor 210. The other end of the seventh resistor R7 is connected to the over-current protection control terminal FO of the power module 220.
One end of the second capacitor C2 is connected to the overcurrent control signal receiving terminal IPM _ FO of the microprocessor 210. The other end of the second capacitor C2 is connected to the ground GND.
Similarly, in this embodiment, the over-current protection signal is a low level signal. Since the voltage across the second capacitor C2 cannot change abruptly, when the output terminal of the comparison circuit 120 outputs a low level signal, the second capacitor C2 (the second capacitor C2 has been charged when the output terminal of the comparison circuit 120 is a high level signal) is discharged through the seventh resistor R7. After a certain time, the second capacitor C2 is discharged completely, so that the intermediate overcurrent control signal receiving terminal IPM _ FO of the microprocessor 210 receives the low level overcurrent protection signal. If there is a low level pulse signal (with a short signal duration) at the output terminal of the comparison circuit 120 due to the presence of the interference signal in the circuit, the second capacitor C2 may not be completely discharged within the pulse duration range of the interference signal, and therefore, the over-current control signal receiving terminal IPM _ FO of the microprocessor 210 may not generate the false triggering phenomenon due to the presence of the interference signal.
Referring to fig. 4, the operation process of the over-current protection circuit 100 according to the embodiment of the present invention is shown as the following steps:
in step 101, the overcurrent protection circuit 100 starts operating.
Step 102, a current detection sampling process is performed. That is, the operating current of the compressor is collected through the sampling resistor R10.
In step 103, it is determined whether the output voltage of the comparator U1A is inverted. If the output voltage of the comparator U1A maintains the high level, the current detection sampling process in step 102 is continuously executed; if the output voltage of the comparator U1A is inverted to a low level, the process proceeds to step 104.
104, on one hand, directly inputting the low-level overcurrent protection signal to the overcurrent protection control end FO of the power module 220 in a hardware fault interrupt processing mode to directly close the output of the power module 220; on the other hand, the low-level overcurrent protection signal is input to the interrupt signal receiving terminal INT of the microprocessor 210 by a software fault interrupt processing method. After the microprocessor 210 determines the type of fault, the output of the power module 220 is turned off.
Please refer to fig. 5 and 6 together. FIG. 5 is a time delay from when the software samples the over-current protection signal to when the over-current fault turns off the compressor drive after the over-current occurs; fig. 6 is a shut-off waveform of an interrupt signal and a compressor output generated by the occurrence of an overcurrent. Therefore, after the overcurrent occurs, the hardware circuit can detect the generation of the overcurrent and realize the rapid turn-off, the time priority is higher than the software overcurrent sampling protection time, and the rapid turn-off of the software overcurrent mode is realized.
It can be seen that the over-current protection circuit 100 provided by the embodiment of the present invention has the following advantages:
1. the software overcurrent protection circuit is reversely connected with the overcurrent protection control end FO of the power module 210 through the first diode D1, so that hardware switching-off triggered after software overcurrent is realized, and the timeliness of overcurrent protection of the whole circuit is improved.
2. For a traditional PFC module and a two-in-one intelligent power module integrated by an IPM module, when overcurrent protection occurs, the power module outputs a protection signal. However, it is not possible to distinguish between the PFC module protection and the IPM module protection according to the protection signal, which causes a problem of protection conflict. The over-current protection circuit 100 provided in the embodiment of the present invention reversely connects the over-current protection signal to the over-current protection control terminal FO of the power module 210 through the first diode D1, so as to implement software determination after hardware protection, thereby implementing over-current protection of the PFC module and the IPM module of the power module combined with the PFC module or independent control of the over-current protection of the IPM module.
3. The forward voltage drop range of the first diode D1 needs to satisfy the voltage range obtained by subtracting the forward voltage drop from the overcurrent interrupt signal, and the voltage range obtained by detecting the pin of the microprocessor 210 and the power module 220, and if the forward voltage drop of the first diode D1 is too high, the high level voltage passing through the first diode D1 is too low, which may cause false triggering.
Another embodiment of the present invention further provides an air conditioning apparatus, including the overcurrent protection circuit 100 according to any one of the above embodiments. Since the air conditioning equipment includes the over-current protection circuit 100 according to any of the above embodiments, technical effects achieved by the air conditioning equipment provided by the embodiment of the present invention and the over-current protection circuit 100 according to any of the above embodiments are also completely the same, and are not described herein again.
It should be noted that the above-mentioned embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above-mentioned embodiments, and any other changes, modifications, substitutions, combinations and simplifications which do not depart from the spirit and principle of the present invention should be regarded as equivalent substitutions and are included in the protection scope of the present invention.
Claims (10)
1. The utility model provides an overcurrent protection circuit for air conditioner control circuit, air conditioner control circuit includes microprocessor and power module, microprocessor be used for to power module output compressor control signal is in order to drive compressor work, its characterized in that, overcurrent protection circuit includes:
the sampling circuit is used for detecting the working current of the compressor in the power module;
and the comparison circuit is used for generating an overcurrent protection signal when the working current of the compressor is greater than a preset value, outputting the overcurrent protection signal to an interrupt signal receiving end of the microprocessor and outputting the overcurrent protection signal to an overcurrent protection control end of the power module.
2. The over-current protection circuit of claim 1, wherein the microprocessor further comprises an over-current control signal receiving terminal connected to an over-current protection control terminal of the power module.
3. The over-current protection circuit of claim 2, further comprising a first diode, wherein a cathode of the first diode is connected to the output terminal of the comparison circuit, and an anode of the first diode is connected to the over-current protection control terminal of the power module and the over-current control signal receiving terminal of the microprocessor.
4. The overcurrent protection circuit as set forth in claim 1, wherein said power module includes an N-pole terminal, said sampling circuit includes a sampling resistor, one end of said sampling resistor is connected to said N-pole terminal, and the other end of said sampling resistor is connected to a common voltage terminal.
5. The overcurrent protection circuit of claim 4, wherein the comparison circuit comprises:
a comparator having a non-inverting input and an inverting input;
and the resistance biasing circuit is used for pressurizing the voltage values at the two ends of the sampling resistor and then respectively transmitting the voltage values to the reverse input end and the non-reverse input end of the comparator.
6. The overcurrent protection circuit of claim 5, wherein the resistive bias circuit comprises:
one end of the first resistor is connected with the inverting input end of the comparator, and the other end of the first resistor is connected with one end of the sampling resistor, which is connected with the N-pole terminal;
one end of the second resistor is connected with the non-inverting input end of the comparator, and the other end of the second resistor is connected with the common voltage end;
one end of the third resistor is connected with the inverting input end of the comparator;
one end of the fourth resistor is connected with the non-inverting input end of the comparator, and the other end of the fourth resistor is connected to one end of the third resistor, which is opposite to the inverting input end of the comparator;
one end of the fifth resistor is connected with a direct-current voltage, and the other end of the fifth resistor is connected to a common terminal of the third resistor and the fourth resistor.
7. The overcurrent protection circuit as set forth in claim 6, wherein resistance values of said first through fourth resistors satisfy the following relationship: the value of R2/(R2+ R4) is greater than the value of R1/(R1+ R3), wherein R1 is the resistance value of the first resistor; r2 is the resistance of the second resistor; r3 is the resistance of the third resistor; r4 is the resistance value of the fourth resistor.
8. The overcurrent protection circuit as set forth in claim 2, further comprising a first delay circuit, one end of said first delay circuit being connected to an output terminal of said comparison circuit, the other end of said first delay circuit being connected to an interrupt signal receiving terminal of said microprocessor;
and/or the overcurrent protection circuit further comprises a second delay circuit, one end of the second delay circuit is connected with the overcurrent control signal receiving end of the microprocessor, and the other end of the second delay circuit is connected with the overcurrent protection control end of the power module.
9. The overcurrent protection circuit as set forth in claim 8, wherein said first delay circuit comprises a sixth resistor and a first capacitor, one end of said sixth resistor is connected to an output terminal of said comparison circuit, and the other end of said sixth resistor is connected to an interrupt signal receiving terminal of said microprocessor; one end of the first capacitor is connected with an interrupt signal receiving end of the microprocessor, and the other end of the first capacitor is connected with a grounding end;
and/or the second delay circuit comprises a seventh resistor and a second capacitor, one end of the seventh resistor is connected with an overcurrent control signal receiving end of the microprocessor, and the other end of the seventh resistor is connected with an overcurrent protection control end of the power module; one end of the second capacitor is connected with an overcurrent control signal receiving end of the microprocessor, and the other end of the second capacitor is connected with a grounding end.
10. An air conditioning apparatus, characterized by comprising the overcurrent protection circuit as set forth in any one of claims 1 to 9.
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| CN202110741165.4A CN113422350B (en) | 2021-06-30 | 2021-06-30 | Overcurrent protection circuit and air conditioning equipment |
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| CN202110741165.4A CN113422350B (en) | 2021-06-30 | 2021-06-30 | Overcurrent protection circuit and air conditioning equipment |
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| CN113422350B CN113422350B (en) | 2023-03-10 |
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| CN113983664A (en) * | 2021-10-29 | 2022-01-28 | 北京小米移动软件有限公司 | Air conditioner, control method thereof, and computer-readable storage medium |
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| CN113422350B (en) | 2023-03-10 |
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