CN111521886A - Phase-loss detection circuit and air conditioner - Google Patents
Phase-loss detection circuit and air conditioner Download PDFInfo
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- CN111521886A CN111521886A CN202010354362.6A CN202010354362A CN111521886A CN 111521886 A CN111521886 A CN 111521886A CN 202010354362 A CN202010354362 A CN 202010354362A CN 111521886 A CN111521886 A CN 111521886A
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Abstract
The invention discloses a phase-lack detection circuit and an air conditioner, wherein the phase-lack detection circuit comprises a three-phase power input end, a phase voltage detection circuit and an output device, the phase voltage detection circuit comprises a first detection branch, a second detection branch and a third detection branch, the first detection branch is used for detecting the difference of phase voltages between UV phases, the second detection branch is used for detecting the difference of phase voltages between VW phases, and the third detection branch is used for detecting the difference of phase voltages between UW phases. The output device determines that the three-phase power supply input end is in a phase failure when the phase voltage difference among the UV phases detected by the first detection branch, the VW phase detected by the second detection branch and the UW phase detected by the third detection branch do not meet the phase balance condition of the three-phase power supply. The invention is used for solving the technical problem that the existing detection circuit can not accurately determine the working condition of the input power supply.
Description
Technical Field
The invention relates to the technical field of air conditioners, in particular to a phase loss detection circuit and an air conditioner.
Background
In the prior art, the power supply of the air conditioner is generally realized by adopting a three-phase alternating current power supply, and the three-phase alternating current is a transmission form of electric energy, and is referred to as three-phase power for short. The three-phase AC power supply consists of three AC potentials with the same frequency, equal amplitude and phase difference of 120 deg. Generally, the phases are referred to as U phase, V phase and W phase. In a practical application circuit, the output condition of a three-phase alternating-current power supply is monitored, and the existing circuit estimates the working condition of an input power supply by detecting the voltage of a direct-current bus through a direct-current bus voltage detection circuit. However, this estimation method cannot accurately determine the operation of the input power.
Disclosure of Invention
The invention mainly aims to provide a phase-loss detection circuit, and aims to solve the technical problem that the existing detection circuit cannot accurately determine the working condition of an input power supply.
In order to achieve the above object, the present invention provides a phase-loss detection circuit, including:
the three-phase power input end is respectively a U-phase power input end, a V-phase power input end and a W-phase power input end;
a phase voltage detection circuit including a first detection branch for detecting a difference in phase voltages between the UV phases, a third detection branch for detecting a difference in phase voltages between the UW phases, and a second detection branch for detecting a difference in phase voltages between the VW phases;
the output device is used for determining that the input end of the three-phase power supply does not lack a phase when the difference of the phase voltages between the UV phases detected by the first detection branch, the difference of the phase voltages between the UW phases detected by the third detection branch and the difference of the phase voltages between the VW phases detected by the second detection branch meet the phase balance condition of the three-phase power supply;
and when the phase voltage difference between the UV phases detected by the first detection branch, the phase voltage difference between the UW phases detected by the third detection branch and the phase voltage difference between the VW phases detected by the second detection branch do not meet the phase balance condition of the three-phase power supply, determining that the three-phase power supply input end is in a phase failure.
In an embodiment, each of the first, second and third detection branches includes:
the energy storage circuit is provided with a first input end, a second input end, a first output end and a second output end, the first input end and the second input end of the energy storage circuit are used for being connected with a power supply input by any two-phase power supply input end in the three-phase power supply input ends, when the difference between voltages of two phases connected to the first input end and the second input end of the energy storage circuit meets a first preset voltage range, the energy storage circuit stores electric energy, and when the difference between the voltages of two phases connected to the first input end and the second input end of the energy storage circuit meets a second preset voltage range, the stored electric energy is released;
the optical coupling circuit, the first input end of optical coupling circuit with energy storage circuit's first output is connected, the second input end of optical coupling circuit with energy storage circuit's second output is connected, is used for the voltage of energy storage circuit output switches on when being greater than or equal to the preset voltage value, with to output device output detection signal.
In an embodiment, the energy storage circuit includes a charge and discharge circuit, a switch circuit and a clamp circuit, the charge and discharge circuit includes a first input end, a second input end, a first output end and a second output end, the first input end of the charge and discharge circuit is the first input end of the energy storage circuit, the second input end of the charge and discharge circuit is connected with the controlled end of the switch circuit, the connection node is the second input end of the energy storage circuit, the first output end of the charge and discharge circuit is connected with the first end of the clamp circuit, the connection node is the first output end of the energy storage circuit, the second output end of the charge and discharge circuit and the second end of the clamp circuit are respectively connected with the first end of the switch circuit, and the second end of the switch circuit is the second output end of the energy storage circuit;
the charging and discharging circuit stores electric energy when the voltage difference between two-phase voltages accessed by the first input end of the charging and discharging circuit and the second input end of the charging and discharging circuit meets a first preset voltage range, and releases the stored electric energy when the voltage difference between two-phase voltages accessed by the first input end of the charging and discharging circuit and the second input end of the charging and discharging circuit meets a second preset voltage range;
the switching circuit is used for being conducted when the first end and the second end of the switching circuit are larger than or equal to a preset voltage value so as to output the electric energy released by the charging and discharging circuit;
the clamping circuit is used for clamping a voltage value between the first output end of the energy storage circuit and the second output end of the energy storage circuit when the charging and discharging circuit stores electric energy.
In an embodiment, the optical coupling circuit includes an optical coupling device, the optical coupling device includes a first input end, a second input end, a first output end and a second output end, the first input end of the optical coupling device is the first input end of the optical coupling circuit, the second input end of the optical coupling device is the second input end of the optical coupling circuit, the first output end of the optical coupling device is the first output end of the optical coupling circuit, and the second output end of the optical coupling device is the second output end of the optical coupling circuit.
In an embodiment, the charge and discharge circuit includes one-way conduction module and energy storage module, one-way conduction module includes first input, first output, second input and second output, the first input of one-way conduction module does charge and discharge circuit's first input, one-way conduction module's first output with energy storage module's first end is connected, its connected node does charge and discharge circuit's first output, one-way conduction module's second input does charge and discharge circuit's second input, one-way conduction module's second output with energy storage module's second end is connected, its connected node is charge and discharge circuit's second input.
In one embodiment, the clamping circuit comprises a first voltage regulator tube, a cathode of the first voltage regulator tube is a first end of the clamping circuit, and an anode of the first voltage regulator tube is a second end of the clamping circuit.
In an embodiment, the open-phase detection circuit further includes a current limiting circuit, and the current limiting circuit is connected between the three-phase power input terminal and the second input terminal of the energy storage circuit.
In an embodiment, the open-phase detection circuit further includes a pull-up circuit, and the pull-up circuit is connected between the first output terminal of the optical coupler circuit and the detection signal output terminal.
In one embodiment, the three-phase power input includes one of a three-phase four-wire power input, a three-phase three-wire power input, and a three-phase five-wire power input.
In an embodiment, the output device is further configured to accumulate the number of times of phase loss at the input end of the three-phase power supply, and determine that the input power supply has a phase-loss fault when the number of times of phase loss is greater than or equal to a preset number of times.
In order to achieve the above object, the present invention further provides an air conditioner including the open-phase detection circuit.
The open-phase detection circuit comprises a three-phase power input end, a phase voltage detection circuit and an output device, wherein the three-phase power input end is respectively a U-phase power input end, a V-phase power input end and a W-phase power input end. The phase voltage detection circuit comprises a first detection branch, a second detection branch and a third detection branch, wherein the first detection branch is used for detecting the difference of phase voltages between UV phases, the second detection branch is used for detecting the difference of phase voltages between VW phases, and the third detection branch is used for detecting the difference of phase voltages between UW phases. The output device determines that the three-phase power supply input end is not open-phase when the difference of the phase voltages between the UV phases detected by the first detection branch, the difference of the phase voltages between the UW phases detected by the third detection branch and the difference of the phase voltages between the VW phases detected by the second detection branch meet the phase balance condition of the three-phase power supply. And when the phase voltage difference between the UV phases detected by the first detection branch, the phase voltage difference between the UW phases detected by the third detection branch and the phase voltage difference between the VW phases detected by the second detection branch do not meet the phase balance condition of the three-phase power supply, determining that the three-phase power supply input end is in a phase failure. Through the scheme, the open-phase detection circuit utilizes the characteristics of the three-phase detection circuit, and determines whether the input voltage of the three-phase power supply reaches the phase balance according to the unbalance degree of any two phases so as to fully detect the working condition of each phase of input power supply, thereby solving the technical problem that the existing detection circuit cannot accurately determine the working condition of the input power supply.
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, 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 the structures shown in the drawings without creative efforts.
FIG. 1 is a block diagram of a phase loss detection circuit according to the present invention;
FIG. 2 is a schematic diagram of a waveform of a detection signal output by a phase voltage detection circuit of the phase-loss detection circuit according to the present invention;
FIG. 3 is a circuit diagram of the open-phase detection circuit according to the present invention;
fig. 4 is a circuit diagram of a control circuit of the air conditioner.
The implementation, functional features and advantages of the objects of the present invention will be further explained with reference to the accompanying drawings.
Detailed Description
In the following, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the drawings in the embodiments of the present invention, and if there is a description related to "first", "second", and the like in the embodiments of the present invention, the description of "first", "second", and the like is only used for descriptive purposes and is not to be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature.
The invention provides a phase-lack detection circuit, which aims to solve the technical problem that a detection circuit in the prior art cannot accurately determine the working condition of an input power supply so as to realize higher-precision estimation of the working condition of the input power supply.
As shown in fig. 1 and 2, in an embodiment, the open-phase detection circuit includes a three-phase power input CN1, a phase voltage detection circuit 50 and an output device 40, where the three-phase power input CN1 is a U-phase power input, a V-phase power input and a W-phase power input, respectively. The phase voltage detection circuit 50 includes a first detection branch 10, a third detection branch 30 and a second detection branch 20.
Wherein the first detecting branch 10 detects a difference in phase voltage between the UV phases, the third detecting branch 30 detects a difference in phase voltage between the UW phases, and the second detecting branch 20 detects a difference in phase voltage between the VW phases. The output device 40 is configured to determine that the three-phase power input terminal CN1 is not open-phase when the difference between the phase voltages of the UV phases detected by the first detection branch 10, the difference between the phase voltages of the UW phases detected by the third detection branch 30, and the difference between the phase voltages of the VW phases detected by the second detection branch 20 satisfy the phase balance condition of the three-phase power supply. When the difference between the phase voltages between the UV phases detected by the first detecting branch 10, the difference between the phase voltages between the UW phases detected by the third detecting branch 30, and the difference between the phase voltages between the VW phases detected by the second detecting branch 20 do not satisfy the phase balance condition of the three-phase power supply, it is determined that the three-phase power supply input terminal CN1 is out of phase. At this time, when none of the three-phase voltages is open, the change of the phase voltage difference between the detected UV phases, the phase voltage difference between the UW phases, and the phase voltage difference between the VW phases over a period of time is detected by the first detection branch 10, the third detection branch 30, and the second detection branch 20 and output as the first detection signal, the second detection signal, and the third detection signal, which can be schematically shown, to form a three-stage waveform as shown in fig. 2-a, and the degree of imbalance between any two stages of the three-stage waveform is fixed. When any phase loss exists in the three-phase voltage, the unbalance degree between any two sections of the three-section waveform is not fixed, and through the process, the phase balance condition of the three-phase power supply is determined to be that the unbalance degree of the three-section waveform formed by the first detection signal, the second detection signal and the third detection signal in a period of time is fixed. Therefore, through the scheme, any phase loss possibly existing in the three-phase voltage can be conveniently and quickly detected, so that whether the voltage input by the three-phase power supply has the phase loss can be further distinguished under the condition that the voltage of the direct-current bus of the three-phase power supply input electric equipment is stable, and the working condition of the input power supply is more accurately determined. As shown in figure 4, when the three-phase power supply is used for supplying power to the control circuit of the air conditioner, the direct-current bus of the air conditioner is provided with the bus capacitor, the service life of the bus capacitor is unstable, and when a phase failure is detected, the power supply of the three-phase power supply can be stopped, so that the phase failure power supply cannot damage the bus capacitor, the harm of the phase failure power supply is greatly reduced, and the service life of the bus capacitor is prolonged. It is worth noting that whether the phase loss is dynamic phase loss or static phase loss at the moment, the phase loss can be detected by the method, and the application range is greatly improved. It should be noted that the imbalance degree refers to a time difference between detected signals, for example, a high level of a first detection signal is a first time, a high level of a second detection signal is a second time, and a time difference between the first time and the second time is the imbalance degree. In addition, if 2-a is a normal three-phase output waveform (the two phases are 120 degrees apart from each other), fig. 2-b is an output waveform in the absence of U phase (the phase angle of V, W is close to 0 degree), fig. 2-c is an output waveform in the absence of V phase (the phase angle of U, W is close to about 164 degrees), and fig. 2-d is an output waveform in the absence of W phase (the phase angle of U, V is close to about 162 degrees).
It should be noted that any connection relationship for realizing signal transmission between the functional circuits may be adopted, but is not limited thereto, in this embodiment, the signal transmission between the functional circuits is realized by adopting the following connection relationship, as shown in fig. 1, the phase voltage detection circuit 50 has six detection terminals and three output terminals, which are respectively a first detection terminal, a second detection terminal, a third detection terminal, a fourth detection terminal, a fifth detection terminal, a sixth detection terminal, a first output terminal, a second output terminal and a third output terminal, the output device 40 has 3 detection signal access terminals, which are respectively a first detection signal access terminal, a second detection signal access terminal and a third detection signal access terminal, the first detection terminal of the phase voltage detection circuit 50 is connected with the V-phase power supply input terminal, the second detection terminal of the phase voltage detection circuit 50 is connected with the U-phase power supply input terminal, the third detection terminal of the phase voltage detection circuit 50 is connected with the W-phase power supply input terminal, a fourth detection end of the phase voltage detection circuit 50 is connected with the V-phase power input end, a fifth detection end of the phase voltage detection circuit 50 is connected with the U-phase power input end, a sixth detection end of the phase voltage detection circuit 50 is connected with the W-phase power input end, a first output end of the phase voltage detection circuit 50 is connected with a first detection signal access end of the output device 40, a second output end of the phase voltage detection circuit 50 is connected with a second detection signal access end of the output device 40, and a third output end of the phase voltage detection circuit 50 is connected with a third detection signal access end of the output device 40.
The first detection end and the second detection end of the phase voltage detection circuit 50 are detection ends of the first detection branch 10, the third detection end and the fourth detection end of the phase voltage detection circuit 50 are detection ends of the second detection branch 20, and the fifth detection end and the sixth detection end of the phase voltage detection circuit 50 are detection ends of the third detection branch 30.
In an embodiment, as shown in fig. 3, each of the first detection branch 10, the third detection branch 30 and the second detection branch 20 includes a tank circuit 101 and an optical coupler circuit 102, where the tank circuit 101 has a first input end, a second input end, a first output end and a second output end, and the first input end and the second input end of the tank circuit 101 form any two detection ends of the phase voltage detection circuit 50, that is, when the tank circuit 101 and the optical coupler circuit 102 form the first detection branch 10, the first input end of the tank circuit 101 is a first detection end of the phase voltage detection circuit 50, and the second input end of the tank circuit 101 is a second detection end of the phase voltage detection circuit 50. A first input end of the optical coupling circuit 102 is connected with a first output end of the energy storage circuit 101, a second input end of the optical coupling circuit 102 is connected with a second output end of the energy storage circuit 101,
the energy storage circuit 101 is connected to a power supply input by any two-phase power supply input end of the three-phase power supply input end CN1, stores electric energy when a difference between voltages of two phases connected to a first input end and a second input end of the energy storage circuit 101 meets a first preset voltage range, and releases the stored electric energy when a difference between voltages of two phases connected to the first input end of the energy storage circuit 101 and the second input end of the energy storage circuit 101 meets a second preset voltage range. The optical coupler circuit 102 is turned on when the voltage output by the tank circuit 101 is greater than or equal to a preset voltage value, so as to output a detection signal to the output device 40. It should be noted that the first preset voltage range may be set as required, and it is only necessary to ensure that the difference between the first input terminal V and the phase voltage at the second input terminal U of the tank circuit 101 falls within the first preset voltage range. The purpose at this time is to perform difference calculation, if there is no phase loss, the finally obtained detection data has a rule, and the imbalance degree of the waveform formed by the detection branch where the energy storage circuit 101 is located in a period of time and the waveform formed by the energy storage circuits 101 of the other two detection branches is fixed. On the contrary, if there is a phase loss, the waveform formed by the tank circuit 101 in the detection branch in a period of time is not fixed with the imbalance degree of the waveforms formed by the tank circuits 101 in the other two detection branches.
In an embodiment, the first predetermined voltage range may be set to be greater than zero, and similarly, the second predetermined voltage range may be set to be less than zero. The purpose of the first preset voltage range at this time is to ensure that the phase voltage connected to the first input terminal of the tank circuit 101 is greater than the phase voltage connected to the second input terminal of the tank circuit 101.
In an embodiment, the energy storage circuit 101 includes a charging and discharging circuit, a switching circuit 1014 and a clamping circuit 1013, the charging and discharging circuit includes a first input terminal, a second input terminal, a first output terminal and a second output terminal, the first input terminal of the charging and discharging circuit is the first input terminal of the energy storage circuit 101, the second input terminal of the charging and discharging circuit is connected to the controlled terminal of the switching circuit 1014, the connection node is the second input terminal of the energy storage circuit 101, the first output terminal of the charging and discharging circuit is connected to the first terminal of the clamping circuit 1013, the connection node is the first output terminal of the energy storage circuit 101, the second output terminal of the charging and discharging circuit and the second terminal of the clamping circuit 1013 are respectively connected to the first terminal of the switching circuit 1014, and the second terminal of the switching circuit 1014 is the second output terminal of the energy.
The charging and discharging circuit stores electric energy when the voltage difference between two-phase voltages accessed by the first input end of the charging and discharging circuit and the second input end of the charging and discharging circuit meets a first preset voltage range, and releases the stored electric energy when the voltage difference between two-phase voltages accessed by the first input end of the charging and discharging circuit and the second input end of the charging and discharging circuit meets a second preset voltage range. The switch circuit 1014 is turned on when the first terminal and the second terminal of the switch circuit 1014 are greater than or equal to a preset voltage value, so as to output the electric energy released by the charge and discharge circuit. The clamp circuit 1013 clamps a voltage value between the first output terminal of the energy storage circuit 101 and the second output terminal of the energy storage circuit 101 when the charging and discharging circuit stores the electric energy.
It should be noted that the first preset voltage range may be set as required, and it is only necessary to ensure that the difference between the first input terminal V of the charge and discharge circuit and the voltage of the second input terminal U phase of the charge and discharge circuit falls within the first preset voltage range. The purpose at this moment is to carry out difference value calculation, if there is no phase loss, the finally obtained detection data has a rule, and the unbalance degree of the waveform formed by the detection branch circuit where the charge-discharge circuit is located in a period of time and the waveform formed by the charge-discharge circuits of the other two detection branches is fixed. On the contrary, if there is a phase loss, the waveform formed by the charging and discharging circuit in the detection branch in which the charging and discharging circuit is located in a period of time is not fixed with the imbalance degree of the waveforms formed by the charging and discharging circuits of the other two detection branches.
In an embodiment, the first predetermined voltage range may be set to be greater than zero, and similarly, the second predetermined voltage range may be set to be less than zero. The purpose of the first preset voltage range at this time is to ensure that the phase voltage connected to the first input terminal of the tank circuit 101 is greater than the phase voltage connected to the second input terminal of the tank circuit 101.
In an embodiment, in order to realize a better isolation function, the optical coupler circuit 102 includes an optical coupler IC1, the optical coupler IC1 includes a first input end, a second input end, a first output end and a second output end, the first input end of the optical coupler IC1 is the first input end of the optical coupler circuit 102, the second input end of the optical coupler IC1 is the second input end of the optical coupler circuit 102, the first output end of the optical coupler IC1 is the first output end of the optical coupler circuit 102, and the second output end of the optical coupler IC1 is the second output end of the optical coupler circuit 102.
Wherein, with opto-coupler IC1 design in this circuit, through combining with the technical scheme of this application, owing to in the testing process, opto-coupler IC 1's the on-time is short, switches on the duty cycle and is less than 10%, consequently, the technical scheme of this application can also make the opto-coupler life-span longer.
In an embodiment, the charging and discharging circuit includes a unidirectional conducting module 1011 and an energy storage module 1012, the unidirectional conducting module 1011 includes a first input end, a first output end, a second input end and a second output end, the first input end of the unidirectional conducting module 1011 is the first input end of the charging and discharging circuit, the first output end of the unidirectional conducting module 1011 is connected with the first end of the energy storage module 1012, a connection node thereof is the first output end of the charging and discharging circuit, the second input end of the unidirectional conducting module 1011 is the second input end of the charging and discharging circuit, the second output end of the unidirectional conducting module 1011 is connected with the second end of the energy storage module 1012, and a connection node thereof is the second input end of the charging and discharging circuit.
As shown in fig. 3, in combination with the energy storage module 1012, when a difference between a voltage at the first input terminal V of the charge/discharge circuit and a voltage at the second input terminal U of the charge/discharge circuit falls within a first preset voltage range, part of the diodes of the unidirectional conduction module 1011 are turned on to form a charging loop, so as to charge the energy storage module 1012. When the difference between the first input terminal V of the charge and discharge circuit and the difference between the phase voltages of the second input terminal U of the charge and discharge circuit falls within a second preset voltage range, part of the diodes of the unidirectional conduction module 1011 are conducted to form a discharge loop, and the discharge loop discharges the energy storage module 1012. Thus, comparison and charging and discharging are realized by a very simple circuit without any control program.
In one embodiment, to simplify the circuit, the energy storage module 1012 is a first capacitor C1.
In one embodiment, to simplify the circuit, the clamp 1013 includes a first voltage regulator ZD1, a cathode of the first voltage regulator ZD1 is a first terminal of the clamp 1013, and an anode of the first voltage regulator ZD1 is a second terminal of the clamp 1013.
In an embodiment, in order to increase the application range of the technical solution of the present invention, the open-phase detection circuit further includes a current limiting circuit, and the current limiting circuit is connected between the three-phase power input terminal CN1 and the second input terminal of the energy storage circuit 101. Meanwhile, if the resistance of the current-limiting resistor of the current-limiting circuit is large, the resistor generates little heat, so that the temperature rise of the current-limiting circuit is low, and the function of protecting the phase-failure detection circuit is achieved. It should be noted that the current limiting circuit may be formed by connecting a plurality of resistors in series.
In an embodiment, as shown in fig. 3, the open-phase detection circuit further includes a pull-up circuit 104, and the pull-up circuit 104 is connected between the first output terminal of the optical coupler circuit 102 and the detection signal output terminal.
At this time, the pull-up circuit 104 may ensure that the output detection signal is stable when the voltage output by the optocoupler IC1 is insufficient.
In an embodiment, the pull-up circuit 104 includes a fourth resistor R4, a fifth resistor R5, and a second capacitor C2, a first end of the fourth resistor R4 and a first end of the fifth resistor R5 are respectively connected to the first output terminal of the optocoupler circuit 102, and a second end of the fourth resistor R4 is connected to the pull-up power source V1; the second terminal of the fifth resistor R5 is connected to the first terminal of the second capacitor C2, the connection node thereof is the first output terminal of the phase voltage detection circuit 50, and the second terminal of the second capacitor C2 is grounded.
In one embodiment, the switching circuit 1014 includes a first transistor Q1 and a third resistor R3, a base of the first transistor Q1 is connected to an emitter of the first transistor Q1, a connection node of the first transistor Q3526 is a controlled terminal of the switching circuit 1014, and a collector of the first transistor Q1 is an output terminal of the switching circuit 1014.
In one embodiment, the three-phase power input CN1 includes one of a three-phase four-wire power input, a three-phase three-wire power input, and a three-phase five-wire power input.
At this time, the three-phase power supply at the three-phase four-wire power supply input terminal is a three-phase three-wire system, and the three-phase power supply at the three-phase three-wire power supply input terminal is a three-phase four-wire system. When the invention is applied to the three-phase three-wire system, the invention can be used for a three-phase power supply 220V system of the three-phase three-wire system only by appropriately changing the resistance value of the current limiting circuit 104, for example, when the current limiting circuit 104 comprises two series 220K current limiting resistors R1 and R2, and deleting one 220K current limiting resistor. A220K current-limiting resistor is deleted, and N lines are added, so that the three-phase power supply 380V system with three-phase four-line system can be used.
In one embodiment, in order to improve the accuracy of the phase loss determination, the output device 40 is further configured to accumulate the number of times of phase loss of the three-phase power input terminal CN1, and determine that the input power has a phase loss fault when the number of times of phase loss is greater than or equal to a preset number of times.
Further, the imbalance is also the time difference between the detection signals.
The unbalance degree of the three-phase under the condition of no phase loss is defined as a first preset value, and the output device 40 is further used for determining that the input power supply has a phase loss fault when the unbalance degree of any two phases in the three-phase is greater than or equal to the first preset unbalance value.
Further, in order to improve the accuracy of the phase failure determination, the output device 40 is further configured to determine that the input power source has a phase failure when the degree of unbalance of any two phases of the three-phase phases is greater than or equal to the first preset unbalance value and the number of times of phase failure is greater than or equal to the preset number of times.
Therefore, in order to further improve the accuracy of the determination, if the degree of unbalance of the three-phase in the case of no open phase is defined as 120 degrees, the output device 40 is also configured to determine that the input power supply has a open-phase fault when the degree of unbalance of any two of the three-phase phases is greater than or equal to 27 degrees and occurs multiple times (10 times) in succession.
In the above embodiments, the number of open phases can be generally preset.
In one embodiment, the output device 40 may be an oscilloscope or a controller.
When the output device 40 is an oscilloscope, the difference between the phase voltages of the UV phases, the difference between the phase voltages of the UW phases detected by the third detection branch 30, and the difference between the phase voltages of the VW phases detected by the second detection branch 20 may be represented by waveforms, as shown in fig. 2, when the balance condition is satisfied, the time difference between any two waveforms is 120 °, at this time, because there may be an error in the detection, the time difference may be set to a certain fluctuation range, and set to a fault-tolerant mechanism, so that the detection accuracy may be improved, when the balance condition is not satisfied, the degree of imbalance of the phases of three waveforms is greater than or equal to 27 ° (for 120 °), and this user may determine by himself or herself according to the waveform diagram.
When the output device 40 is a controller, the difference between the phase voltages of the UV phases, the difference between the phase voltages of the UW phases detected by the third detection branch 30, and the difference between the phase voltages of the VW phases detected by the second detection branch 20 may be directly determined, the time difference (unbalance) between the waveform of the difference between the individual phase voltages and the waveform of the difference between the other phase voltages is calculated, when the balance condition is satisfied, the time difference between any two waveforms is 120 °, the time difference is set to a certain fluctuation range, and the fluctuation range is set as a fault-tolerant mechanism, so that the detection accuracy may be improved, when the balance condition is not satisfied, the unbalance of the phases of three waveforms is greater than or equal to 27 ° (for 120 °), and the controller performs self-determination according to the determination method. After the judgment, if the phase-lack fault is detected, the controller can also output a control signal to control the three-phase power supply to stop supplying power or control the electric appliance to stop working, and can also output prompt signals such as voice, light and the like to remind a user of the phase-lack fault of the power supply.
The principle of the invention is explained below with reference to fig. 1, 2 and 3:
when the voltage of the V phase is higher than that of the U phase, the first diode and the second diode are conducted, and a charging loop is formed by the fourth diode and the U phase (through the first resistor and the second resistor). The first capacitor C1 is charged, when the voltage of the first capacitor C1 is greater than 5.6V, the first zener diode is turned on to clamp the voltage at two ends of the first capacitor C1 at about 5.6V, at this time, because the voltage of the U phase is lower than the voltage of the V phase, the base of the first triode Q1 is reversely biased, the first triode Q1 is in a cut-off state, the optocoupler IC1 is not turned on, and the first detection signal access end of the output device 40 is at a high level.
When the voltage of the V phase is lower than that of the U phase, the first diode and the second diode are cut off, when the voltage of the U phase (passing through the first resistor and the second resistor) continues to rise, and the voltage of the base electrode of the first triode Q1 is larger than 0.7V, the first triode Q1 is conducted, the electricity of the first capacitor C1 is discharged through the optocoupler IC1, the third resistor R3, the first triode Q1 and the third diode, the first output end of the optocoupler IC1 is at a low level, the duration time of the low level is about 1 mS-2 mS, after the electricity of the first capacitor C1 is discharged, the light emitting diode in the optocoupler IC1 stops working, the output of the optocoupler IC1 is recovered to be at a high level again, and the low level is triggered again until the voltage of the V phase is lower than that of the U phase next time.
By the technical scheme, the voltage of the input end of each phase of power supply is detected, and the phase-lack information of the voltage of each phase of power supply is accurately acquired, so that the working condition of the input power supply is accurately determined. The service life of the electric appliance and the three-phase power supply can be prolonged.
In order to achieve the above object, the present invention further provides a three-phase power supply including the above open-phase detection circuit.
It should be noted that, since the three-phase power supply of the present invention includes all embodiments of the open-phase detection circuit, the three-phase power supply of the present invention has all the advantages of the open-phase detection circuit, and will not be described herein again.
In order to achieve the above object, the present invention further provides an air conditioner including the above open-phase detection circuit or the above three-phase power supply.
It should be noted that, since the air conditioner of the present invention includes all embodiments of the open-phase detection circuit, the air conditioner of the present invention has all the advantages of the open-phase detection circuit, and thus, the detailed description thereof is omitted.
Claims (11)
1. A phase loss detection circuit, comprising:
the three-phase power input end is respectively a U-phase power input end, a V-phase power input end and a W-phase power input end;
a phase voltage detection circuit including a first detection branch for detecting a difference in phase voltages between the UV phases, a second detection branch for detecting a difference in phase voltages between the VW phases, and a third detection branch for detecting a difference in phase voltages between the UW phases;
the output device is used for determining that the input end of the three-phase power supply does not lack a phase when the difference of the phase voltages between the UV phases detected by the first detection branch, the difference of the phase voltages between the VW phases detected by the second detection branch and the difference of the phase voltages between the UW phases detected by the third detection branch meet the phase balance condition of the three-phase power supply;
and when the phase voltage difference between the UV phases detected by the first detection branch, the phase voltage difference between the VW phases detected by the second detection branch and the phase voltage difference between the UW phases detected by the third detection branch do not meet the phase balance condition of the three-phase power supply, determining that the three-phase power supply input end is in a phase failure.
2. The open-phase detection circuit of claim 1, wherein each of the first, second, and third detection branches comprises:
the energy storage circuit is provided with a first input end, a second input end, a first output end and a second output end, the first input end and the second input end of the energy storage circuit are used for being connected with a power supply input by any two-phase power supply input end in the three-phase power supply input ends, when the difference between voltages of two phases connected to the first input end and the second input end of the energy storage circuit meets a first preset voltage range, the energy storage circuit stores electric energy, and when the difference between the voltages of two phases connected to the first input end and the second input end of the energy storage circuit meets a second preset voltage range, the stored electric energy is released;
the optical coupling circuit, the first input end of optical coupling circuit with energy storage circuit's first output is connected, the second input end of optical coupling circuit with energy storage circuit's second output is connected, is used for the voltage of energy storage circuit output switches on when being greater than or equal to the preset voltage value, with to output device output detection signal.
3. The open-phase detection circuit of claim 2, wherein the tank circuit comprises a charge-discharge circuit, a switching circuit, and a clamping circuit, the charge and discharge circuit comprises a first input end, a second input end, a first output end and a second output end, the first input end of the charge and discharge circuit is the first input end of the energy storage circuit, the second input end of the charge and discharge circuit is connected with the controlled end of the switch circuit, the connection node is the second input end of the energy storage circuit, the first output end of the charge and discharge circuit is connected with the first end of the clamping circuit, the connection node of the energy storage circuit is a first output end of the energy storage circuit, a second output end of the charge and discharge circuit and a second end of the clamping circuit are respectively connected with a first end of the switch circuit, and a second end of the switch circuit is a second output end of the energy storage circuit;
the charging and discharging circuit stores electric energy when the voltage difference between two-phase voltages accessed by the first input end of the charging and discharging circuit and the second input end of the charging and discharging circuit meets a first preset voltage range, and releases the stored electric energy when the voltage difference between two-phase voltages accessed by the first input end of the charging and discharging circuit and the second input end of the charging and discharging circuit meets a second preset voltage range;
the switching circuit is used for being conducted when the first end and the second end of the switching circuit are larger than or equal to a preset voltage value so as to output the electric energy released by the charging and discharging circuit;
the clamping circuit is used for clamping a voltage value between the first output end of the energy storage circuit and the second output end of the energy storage circuit when the charging and discharging circuit stores electric energy.
4. The open-phase detection circuit according to claim 2, wherein the optical coupler circuit comprises an optical coupler device, the optical coupler device comprises a first input end, a second input end, a first output end and a second output end, the first input end of the optical coupler device is the first input end of the optical coupler circuit, the second input end of the optical coupler device is the second input end of the optical coupler circuit, the first output end of the optical coupler device is the first output end of the optical coupler circuit, and the second output end of the optical coupler device is the second output end of the optical coupler circuit.
5. The open-phase detection circuit according to claim 3, wherein the charge and discharge circuit comprises a unidirectional conduction module and an energy storage module, the unidirectional conduction module comprises a first input end, a first output end, a second input end and a second output end, the first input end of the unidirectional conduction module is the first input end of the charge and discharge circuit, the first output end of the unidirectional conduction module is connected with the first end of the energy storage module, the connection node thereof is the first output end of the charge and discharge circuit, the second input end of the unidirectional conduction module is the second input end of the charge and discharge circuit, the second output end of the unidirectional conduction module is connected with the second end of the energy storage module, and the connection node thereof is the second input end of the charge and discharge circuit.
6. The open-phase detection circuit of claim 3, wherein the clamp circuit comprises a first regulator tube, a cathode of the first regulator tube being a first end of the clamp circuit, and an anode of the first regulator tube being a second end of the clamp circuit.
7. The open-phase detection circuit of claim 2, further comprising a current limiting circuit coupled between the three-phase power input and the second input of the tank circuit.
8. The phase loss detection circuit of claim 2, further comprising a pull-up circuit connected between the first output of the optocoupler circuit and the detection signal output.
9. A phase loss detection circuit as claimed in any one of claims 1 to 8, wherein the three phase power input comprises one of a three phase four wire power input, a three phase three wire power input and a three phase five wire power input.
10. The open-phase detection circuit as claimed in any one of claims 1 to 8, wherein the output device is further configured to accumulate the number of open-phase times of the three-phase power input terminal, and determine that the input power has an open-phase fault when the number of open-phase times is greater than or equal to a preset number; and/or the presence of a gas in the gas,
and the output device is also used for determining that the input power supply has a phase failure when the unbalance degree of any two phases in the three-phase phases is greater than or equal to a first preset unbalance value.
11. An air conditioner characterized by comprising the open-phase detection circuit according to any one of claims 1 to 9.
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