CN113007084B - Compressor fault early warning method and device - Google Patents
Compressor fault early warning method and device Download PDFInfo
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- CN113007084B CN113007084B CN202110220072.7A CN202110220072A CN113007084B CN 113007084 B CN113007084 B CN 113007084B CN 202110220072 A CN202110220072 A CN 202110220072A CN 113007084 B CN113007084 B CN 113007084B
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B51/00—Testing machines, pumps, or pumping installations
Abstract
The invention relates to the technical field of compressors, in particular to a method and a device for early warning of a fault of a compressor, and aims to solve the technical problem of timely and effectively monitoring whether a three-phase unbalanced fault occurs before the compressor enters a stable running state. For this purpose, the method according to the embodiment of the invention can respond to the received starting instruction of the frequency converter to detect the driving current of the frequency converter; and pre-judging whether the compressor fails after starting according to the detection result of the driving current, and if so, timely early warning can be performed before the compressor is started, so that a user is reminded to adopt effective measures, and the compressor is prevented from being damaged due to the operation of the compressor in a failure state.
Description
Technical Field
The invention relates to the technical field of compressors, in particular to a fault early warning method and device for a compressor.
Background
The compressor is used as core equipment of the air conditioning system, and if the compressor fails, the normal operation of the air conditioning system can be greatly influenced. For example, if a current imbalance fault occurs in the three-phase windings of the compressor, the temperature of the over-current windings may increase continuously as the compressor operates, thereby burning out the windings and causing the compressor to stop. However, the conventional three-phase imbalance fault detection method at present can only detect when the compressor stably runs, and because the starting current is large when the compressor is started, if the external power supply of the compressor is unbalanced in three phases, the three-phase imbalance fault can also occur when the compressor is started, and the current in the overcurrent winding can be increased sharply, so that the more serious damage to the compressor is likely to be caused.
Accordingly, there is a need in the art for a new compressor failure detection scheme to address the above-described problems.
Disclosure of Invention
The present invention is made to overcome the above-mentioned drawbacks, and provides a compressor fault early warning method and apparatus for solving or at least partially solving the technical problem of how to timely and effectively monitor whether a three-phase imbalance fault occurs before the compressor enters a stable operation state.
In a first aspect, there is provided a fault warning method for a compressor, the compressor being connected to a frequency converter configured to convert electric energy from an input power source to output a driving current to the compressor, the method comprising:
responding to a received starting instruction of the frequency converter, and detecting the driving current of the frequency converter;
judging whether the three-phase driving current output by the frequency converter is unbalanced according to the detection result;
if so, the three-phase imbalance fault can be prejudged and the alarm is given after the compressor is started.
In one technical scheme of the foregoing compressor fault early warning method, the frequency converter includes a three-phase full-bridge inverter, an ac side of the three-phase full-bridge inverter is connected with the compressor, the three-phase full-bridge inverter includes three-phase bridge arms, each phase bridge arm includes an upper bridge arm and a lower bridge arm, and the step of "detecting driving current of the frequency converter" specifically includes:
for each phase of bridge arm, driving current detection is carried out through the following steps to obtain a current detection result of three driving current detection:
setting a current phase bridge arm as a main phase detection bridge arm, and setting other two phase bridge arms as detected phase bridge arms;
driving an upper bridge arm of the main phase detection bridge arm and a lower bridge arm of each detected phase bridge arm to be conducted according to a preset PWM signal, so that the input power supply is transmitted through a conducting loop formed by the upper bridge arm, the compressor and one lower bridge arm, and the input power supply is transmitted through a conducting loop formed by the upper bridge arm, the compressor and the other lower bridge arm; wherein the preset PWM signal is a PWM signal generated according to a given value of the driving current;
and collecting the actual value of the driving current transmitted on each detected phase bridge arm to obtain a current detection result of the current driving current detection.
In one technical scheme of the foregoing compressor fault early warning method, the step of "judging whether the three-phase driving current output by the frequency converter is unbalanced according to the detected result" specifically includes:
respectively judging whether currents transmitted on two detected phase bridge arms in current detection results of each driving current detection are balanced or not;
if the currents transmitted on the two detected phase bridge arms in the current detection results of at least one driving current detection are unbalanced, the imbalance of the three-phase driving current output by the frequency converter is judged.
In one technical scheme of the foregoing compressor fault early warning method, the step of "determining whether currents transmitted on two detected phase legs are balanced in current detection results of each driving current detection" specifically includes:
for the current detection result of each driving current detection, judging whether currents transmitted on two detected phase bridge arms in the current detection result are balanced or not through the following steps:
and respectively calculating the current deviation degree of the actual value of the driving current transmitted on each detected phase bridge arm in the current detection result by adopting a deviation degree calculation function shown as follows:
wherein d represents the current deviation degree, I r Representing the actual value of the driving current, wherein I represents the given value of the driving current;
judging whether each current deviation degree is smaller than a preset deviation degree threshold value or not;
if yes, judging the current balance transmitted on the two detected phase bridge arms; if not, the unbalance of the currents transmitted on the two detected phase bridge arms is judged.
In one technical solution of the foregoing compressor fault early warning method, after the step of "determining that the three-phase driving current output by the inverter is unbalanced", the method further includes:
and calculating the unbalance of the three-phase driving current output by the frequency converter according to the current detection result of the three-time driving current detection by adopting a three-phase unbalance calculation method.
In a second aspect, there is provided a fault warning apparatus for a compressor, the compressor being connected to a frequency converter configured to convert electric energy of an input power source to output a driving current to the compressor, the apparatus driving the compressor to operate, the apparatus comprising:
a current detection module configured to detect a drive current for the frequency converter in response to a received frequency converter start instruction;
a failure pre-judging module configured to judge whether the three-phase driving current output by the frequency converter is unbalanced according to the detected result; if so, the three-phase imbalance fault can be prejudged and the alarm is given after the compressor is started.
In one technical scheme of the foregoing compressor fault early warning device, the frequency converter includes a three-phase full-bridge inverter, an ac side of the three-phase full-bridge inverter is connected with the compressor, the three-phase full-bridge inverter includes three-phase bridge arms, each phase bridge arm includes an upper bridge arm and a lower bridge arm, and the current detection module is further configured to perform driving current detection for each phase bridge arm through the following steps, so as to obtain a current detection result of three driving current detection:
setting a current phase bridge arm as a main phase detection bridge arm, and setting other two phase bridge arms as detected phase bridge arms;
driving an upper bridge arm of the main phase detection bridge arm and a lower bridge arm of each detected phase bridge arm to be conducted according to a preset PWM signal, so that the input power supply is transmitted through a conducting loop formed by the upper bridge arm, the compressor and one lower bridge arm, and the input power supply is transmitted through a conducting loop formed by the upper bridge arm, the compressor and the other lower bridge arm; wherein the preset PWM signal is a PWM signal generated according to a given value of the driving current;
and collecting the actual value of the driving current transmitted on each detected phase bridge arm to obtain a current detection result of the current driving current detection.
In one aspect of the foregoing compressor fault pre-warning device, the fault pre-determining module includes a current analysis unit configured to perform the following operations:
respectively judging whether currents transmitted on two detected phase bridge arms in current detection results of each driving current detection are balanced or not;
if the currents transmitted on the two detected phase bridge arms in the current detection results of at least one driving current detection are unbalanced, the imbalance of the three-phase driving current output by the frequency converter is judged.
In one aspect of the above compressor fault warning device, the current analysis unit is further configured to perform the following operations:
for the current detection result of each driving current detection, judging whether currents transmitted on two detected phase bridge arms in the current detection result are balanced or not through the following steps:
and respectively calculating the current deviation degree of the actual value of the driving current transmitted on each detected phase bridge arm in the current detection result by adopting a deviation degree calculation function shown as follows:
wherein d represents the current deviation degree, I r Representing the actual value of the driving current, wherein I represents the given value of the driving current;
judging whether each current deviation degree is smaller than a preset deviation degree threshold value or not;
if yes, judging the current balance transmitted on the two detected phase bridge arms; if not, the unbalance of the currents transmitted on the two detected phase bridge arms is judged.
In one aspect of the foregoing compressor fault pre-warning device, the fault pre-judging module includes an unbalance calculating unit configured to calculate the unbalance of the three-phase driving current output by the frequency converter by using a three-phase unbalance calculating method and according to a current detection result of three-time driving current detection.
The technical scheme provided by the invention has at least one or more of the following beneficial effects:
in the technical scheme of the invention, the driving current of the frequency converter can be detected in response to the received starting instruction of the frequency converter; judging whether the three-phase driving current output by the frequency converter is unbalanced according to the detection result; if the three-phase driving current is unbalanced, the three-phase unbalanced fault can occur and alarm is given out after the pre-judging compressor is started. Through the embodiment, when the compressor is controlled to start to operate (in the starting process of the compressor) and the compressor is not started, whether the compressor fails after the compressor is started or not can be judged according to the detection result of the driving current, if the compressor fails, early warning can be carried out in time before the compressor is started, a user is reminded to adopt effective measures, and the compressor is prevented from being damaged due to the fact that the compressor is operated in a failure state.
Drawings
Embodiments of the invention are described below with reference to the accompanying drawings, in which:
FIG. 1 is a flow chart illustrating the main steps of a compressor fault warning method according to one embodiment of the present invention;
FIG. 2 is a block diagram of the main structure of a compressor failure warning apparatus according to an embodiment of the present invention;
fig. 3 is a main connection structure diagram of the three-phase full-bridge inverter and the compressor.
List of reference numerals:
11: a current detection module; 12: a fault pre-judging module; 21: a direct current bus; 22: a three-phase full-bridge inverter; 3: a compressor.
Detailed Description
Some embodiments of the invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are merely for explaining the technical principles of the present invention, and are not intended to limit the scope of the present invention.
In the description of the present invention, a "module," "processor" may include hardware, software, or a combination of both. A module may comprise hardware circuitry, various suitable sensors, communication ports, memory, or software components, such as program code, or a combination of software and hardware. The processor may be a central processor, a microprocessor, an image processor, a digital signal processor, or any other suitable processor. The processor has data and/or signal processing functions. The processor may be implemented in software, hardware, or a combination of both. Non-transitory computer readable storage media include any suitable medium that can store program code, such as magnetic disks, hard disks, optical disks, flash memory, read-only memory, random access memory, and the like. The term "a and/or B" means all possible combinations of a and B, such as a alone, B alone or a and B. The term "at least one A or B" or "at least one of A and B" has a meaning similar to "A and/or B" and may include A alone, B alone or A and B. The singular forms "a", "an" and "the" include plural referents.
Some terms related to the present invention will be explained first.
The three-phase full-bridge inverter in the frequency converter refers to a three-phase inverter adopting a full-bridge structure, the three-phase inverter can convert direct current into three-phase alternating current, the three-phase full-bridge inverter is connected with the compressor, and the three-phase alternating current output by the three-phase full-bridge inverter can be utilized to drive the compressor to move. The three-phase full-bridge inverter comprises three-phase bridge arms, and each phase of bridge arm comprises an upper bridge arm and a lower bridge arm, namely an upper bridge arm and a lower bridge arm. Each upper leg and each lower leg includes controllable power electronics. One example is: the upper bridge arm and the lower bridge arm in each phase bridge arm comprise a controllable power electronic device, a first main electrode of the controllable power electronic device positioned in the upper bridge arm in each phase bridge arm is connected with the positive electrode of a direct current bus, a second main electrode of the controllable power electronic device positioned in the upper bridge arm in each phase bridge arm is connected with a first main electrode of the controllable power electronic device positioned in the lower bridge arm in the corresponding bridge arm, a second main electrode of the controllable power electronic device positioned in the lower bridge arm in each phase bridge arm is connected with the negative electrode of the direct current bus, and three-phase windings of the compressor are respectively connected between the controllable power electronic devices positioned in the upper bridge arm and the lower bridge arm in the three-phase bridge arm.
The controllable power electronic device may be a fully controlled power semiconductor device, such as a Metal-Oxide-semiconductor field effect transistor (MOSFET), an insulated gate bipolar transistor (Insulated Gate Bipolar Transistor, IGBT) or an integrated gate commutated thyristor (Integrated Gate Commutated Thyristors, IGCT), etc. Also, these fully controlled power semiconductor devices are all three terminal devices, such as MOSFETs comprising a source, a drain and a gate, IGBTs comprising a collector, an emitter and a gate, IGCTs comprising a collector, an emitter and a gate. Wherein the source, drain, collector and emitter are main electrodes and the gate and gate are control electrodes. For clarity of description of the structure of the power electronic device, the main electrode in the power input direction in the power electronic device is described as a first main electrode (such as the drain of the MOSFET and the collector of the IGBT), and the main electrode in the power output direction is described as a second main electrode (such as the source of the MOSFET and the emitter of the IGBT).
In the present invention, "up/down" of the upper/lower arm is not up/down in the spatial structure, but up/down relationship determined by the electrode connection relationship of the power electronic device. Specifically, a first main electrode (for example, a collector of an IGBT) of the power electronic device positioned on the upper arm is connected with a positive electrode of a power supply, a second main electrode (for example, an emitter of the IGBT) of the power electronic device positioned on the upper arm is connected with a first main electrode (for example, a collector of the IGBT) of the power electronic device positioned on the lower arm, and a second main electrode (for example, an emitter of the IGBT) of the power electronic device positioned on the lower arm is connected with a negative electrode of the power supply. Further, the power electronic devices in the upper bridge arm and the lower bridge arm can be replaced by a power electronic device unit formed by connecting a plurality of power electronic devices in series, and the electrode connection relationship of the two power electronic device units is similar to that of the power electronic devices in the upper bridge arm and the lower bridge arm, so that the description is omitted herein for brevity.
Referring first to fig. 3, fig. 3 schematically illustrates a main connection structure of a three-phase full-bridge inverter and a compressor in a frequency converter according to an embodiment of the present invention. As shown in fig. 1, two dc side terminals of the three-phase full-bridge inverter 22 are connected to the positive electrode P and the negative electrode N of the dc bus 21, respectively, and three ac side terminals of the three-phase full-bridge inverter 22 are connected to the windings U, V and W of the compressor 3, respectively, and the equivalent voltage of the dc bus 11 can be represented by the voltage Vdc across the capacitor C. The three-phase full-bridge inverter 22 includes three-phase legs, each of which includes an upper leg and a lower leg. Each upper leg and each lower leg includes a power switch assembly, each power switch assembly including an antiparallel controllable power electronics and a diode. Specifically, the upper bridge arm of the U-phase bridge arm includes a power switch assembly formed by antiparallel a controllable power electronic device VT1 and a diode VD1, the lower bridge arm of the U-phase bridge arm includes a power switch assembly formed by antiparallel a controllable power electronic device VT2 and a diode VD2, the upper bridge arm of the V-phase bridge arm includes a power switch assembly formed by antiparallel a controllable power electronic device VT3 and a diode VD3, the lower bridge arm of the V-phase bridge arm includes a power switch assembly formed by antiparallel a controllable power electronic device VT4 and a diode VD4, the upper bridge arm of the W-phase bridge arm includes a power switch assembly formed by antiparallel a controllable power electronic device VT5 and a diode VD5, the lower bridge arm of the W-phase bridge arm includes a power switch assembly formed by antiparallel a controllable power electronic device VT6 and a diode VD6, the U-phase winding of the compressor is connected between VT1 and VT2, the V-phase winding is connected between VT3 and VT4, and the W-phase winding is connected between VT5 and VT 6.
With continued reference to fig. 1, fig. 1 is a schematic flow chart of main steps of a fault early warning method for a compressor according to an embodiment of the present invention, in this embodiment, the compressor may be connected to a three-phase full-bridge inverter in a frequency converter in a connection manner shown in fig. 3, and the frequency converter may perform electrical energy conversion on an input power source to output a driving current to the compressor, so that the compressor operates under the control of the driving current. As shown in fig. 1, the method for early warning of a fault of a compressor in an embodiment of the present invention mainly includes the following steps S101 to S104.
Step S101: and responding to the received starting instruction of the frequency converter, and detecting the driving current of the frequency converter.
The frequency converter starting instruction refers to a starting instruction which is output to the frequency converter when the compressor starts to operate, and the frequency converter can perform electric energy conversion on electric energy output by an external power supply under the control of the starting instruction, and the electric energy after electric energy conversion is output to the compressor (three-phase driving current is output to the compressor) so as to drive the compressor to start to operate. That is, this embodiment can carry out the drive current electricity survey to the converter when the compressor is not yet accomplished in the control compressor start-up in-process (in the compressor start-up process) and the compressor to judge whether the compressor can break down after the start-up according to drive current detection's result in advance, if judge in advance can in time early warning before the compressor is accomplished to start up, remind the user to adopt effective measure, prevent that the compressor from breaking down in the operation of fault state.
In the embodiment of the invention, whether the three-phase imbalance fault occurs after the compressor is started can be pre-judged by analyzing whether the three-phase imbalance occurs in the driving current output by the frequency converter. If the frequency converter is analyzed to be unbalanced in three-phase current, the situation that the external power supply is unbalanced in three-phase voltage/power supply is indicated, and further, the driving current output by the frequency converter is unbalanced, and if the compressor is started to operate under the power supply of the external power supply, three-phase unbalance faults are likely to occur. Specifically, in one implementation manner of the embodiment of the present invention, for each phase of bridge arm, driving current detection may be performed through the following steps 11 to 13, so as to obtain a current detection result of three driving current detection, and further, whether the driving current output by the frequency converter is unbalanced in three phases is analyzed according to the current detection result of three driving current detection.
Step 11: the current phase bridge arm is set as a main phase detection bridge arm, and other two phase bridge arms are set as detected phase bridge arms. The detected phase bridge arm refers to a bridge arm which needs to judge whether current unbalance occurs in the current driving current detection.
Referring to fig. 3, if the current phase leg is a U phase leg, the U phase leg may be set as a main phase detection leg, and the V phase leg and the W phase leg may be set as detected phase legs.
Step 12: driving an upper bridge arm of a main phase detection bridge arm and a lower bridge arm of each detected phase bridge arm to be conducted according to a preset PWM signal, so that an input power supply is transmitted through a conducting loop formed by the upper bridge arm, a compressor and one lower bridge arm, and the input power supply is transmitted through a conducting loop formed by the upper bridge arm, the compressor and the other lower bridge arm; the preset PWM signal is generated according to the given value of the driving current.
In this embodiment, a pulse width modulation (Pulse Width Modulation) method, which is conventional in the field of power electronics, may be used to generate the PWM signal according to the set value of the driving current. For brevity, a detailed process of generating the PWM signal by using the pulse width modulation method will not be described herein. In addition, the specific value of the given value of the driving current can be flexibly set according to actual requirements by a person skilled in the art, for example, the given value of the driving current can be set to be the driving current value required by the normal operation of the compressor, and the given value of the driving current can also be set to be the rated driving current value of the compressor.
With continued reference to fig. 3, taking the example that the main phase detection bridge arm is a U-phase bridge arm and the detected phase bridge arm is a V-phase bridge arm and a W-phase bridge arm, the controllable power electronic device VT1 can be driven to be turned on according to a preset PWM signal to turn on the upper bridge arm of the U-phase bridge arm, the controllable power electronic device VT4 can be driven to be turned on to turn on the lower bridge arm of the V-phase bridge arm, and the controllable power electronic device VT6 can be driven to be turned on to turn on the lower bridge arm of the W-phase bridge arm. The positive electrode P, VT1 of the direct current bus 21, the compressors 3 and VT4 and the negative electrode N of the direct current bus 21 form a conducting loop, and the positive electrode P, VT of the direct current bus 21, the compressors 3 and VT6 and the negative electrode N of the direct current bus 21 form another conducting loop. And the three-phase alternating current external power supply is respectively transmitted through the two conduction loops after being rectified by the three-phase full-bridge rectifier of the frequency converter.
Step 13: and collecting the actual value of the driving current transmitted on each detected phase bridge arm to obtain a current detection result of the current driving current detection.
With continued reference to FIG. 3, the current sense result of the present drive current sense includes the current I transmitted on the V-phase leg V And current I transmitted on the W-phase bridge arm W . Further, if the current phase leg is a V-phase leg, the current detection result obtained through the steps 11-13 includes the current I transmitted on the U-phase leg U And current I transmitted on the W-phase bridge arm W . If the current phase bridge arm is a W-phase bridge arm, the current detection result obtained through the steps 11-13 includes the current I transmitted on the U-phase bridge arm U And current I transmitted on the V-phase bridge arm V . That is, through three drivesThe current measurement can obtain two actual driving current values for each phase of bridge arm, and in order to clearly describe the two actual driving current values, the actual driving current values transmitted on the two U-phase bridge arms obtained by three driving current measurement are expressed as I U1 And I U2 The actual value of the driving current transmitted on the two V-phase bridge arms obtained by three driving current electric measurement is expressed as I V1 And I V2 The actual value of the driving current transmitted on two W-phase bridge arms obtained by three driving current electric measurement is expressed as I W1 And I W2 。
Step S102: judging whether the three-phase driving current output by the frequency converter is unbalanced; if the judgment is unbalanced, the three-phase unbalance fault occurs after the starting of the pre-judging compressor and the alarm is given (step S103); if it is determined that the compressor is balanced, it is determined that no three-phase imbalance fault occurs after the start of the compressor and an alarm is given, so that an alarm is not required (step S104).
In step S102, it may be determined whether the currents transmitted on the two detected phase legs in the current detection results of each driving current detection are balanced, and if the currents transmitted on the two detected phase legs in the current detection results of at least one driving current detection are unbalanced, it is determined that the three-phase driving currents output by the frequency converter are unbalanced. With continued reference to FIG. 3, if the current sense result of the present drive current sense includes the current I transmitted across the V-phase leg V And current I transmitted on the W-phase bridge arm W And I V And I W Imbalance can then judge the three-phase drive current unbalance of converter output.
In one implementation manner of the embodiment of the present invention, for each current detection result of driving current detection, it may be determined whether currents transmitted on two detected phase legs in the current detection results are balanced through the following steps 21 to 22.
Step 21: calculating the current deviation degree of the actual value of the driving current transmitted on each detected phase bridge arm in the current detection result by adopting a deviation degree calculation function shown in the following formula (1):
the meaning of each parameter in the formula (1) is: d represents the current deviation degree, I r Representing the actual value of the drive current, I representing the given value of the drive current.
With continued reference to FIG. 3, if the current sense result of the present drive current sense includes the current I transmitted across the V-phase leg V And current I transmitted on the W-phase bridge arm W And I V And I W Imbalance can be calculated according to equation (1): current I V Is of the degree of deviation of the current of (2)
Current I W Is +.>
Step 22: and judging whether each current deviation degree is smaller than a preset deviation degree threshold value. If each current deviation degree is smaller than a preset deviation degree threshold value, such as 10%, the current balance transmitted on the two detected phase bridge arms can be judged; if at least one current deviation is greater than or equal to a preset deviation threshold, the imbalance of the currents transmitted on the two detected phase bridge arms can be determined.
Further, after the unbalance of the three-phase driving current outputted from the inverter is determined (step S103), the unbalance of the three-phase driving current outputted from the inverter may be calculated by a three-phase unbalance calculation method based on the current detection result of the three-time driving current detection (step S105).
In particular, referring to fig. 3, in one implementation of the embodiment of the present invention, if the actual value I of the driving current transmitted on the U-phase bridge arm is obtained through three driving current electrical measurements U1 And I U2 Actual value I of drive current transmitted on V-phase bridge arm V1 And I V2 Actual value I of drive current transmitted on W-phase bridge arm W1 And I W2 Then the two actual driving current values of each phase bridge arm can be obtained respectivelyAnd calculating a driving current of each phase of bridge arm. For example: the average or accumulated value of the two actual values of the drive current may be taken as the drive current calculation value. And further, a three-phase unbalance degree calculation method is adopted, and the unbalance degree of the three-phase driving current output by the frequency converter is calculated according to the driving current calculation value of each phase of bridge arm. For example: the driving current calculated value of U, V, W phase bridge arm can be I in turn U1 +I U2 、I V1 +I V2 、I W1 +I W2 The driving current calculated value of U, V, W phase bridge arm can be sequentially as follows
In this embodiment, a conventional three-phase imbalance calculation method may be used to calculate the imbalance of the three-phase driving current output by the inverter according to the driving current calculation value of each phase of bridge arm. One example is: the maximum driving current calculated value and the minimum driving current calculated value in the driving current calculated values of each phase of bridge arm can be respectively obtained, then the deviation of the maximum driving current calculated value and the minimum driving current calculated value is calculated, and finally the ratio of the deviation to the maximum driving current calculated value is calculated, wherein the ratio can be set as the unbalance degree of the three-phase driving current output by the frequency converter. Yet another example is: the average value of the driving current calculated values of the three-phase bridge arms can be obtained, the deviation between the driving current calculated value of each phase bridge arm and the average value is calculated, the maximum deviation is selected, and finally the ratio of the maximum deviation to the average value is calculated, and can be set as the unbalance degree of the three-phase driving current output by the frequency converter.
It should be noted that, although the foregoing embodiments describe the steps in a specific order, it will be understood by those skilled in the art that, in order to achieve the effects of the present invention, the steps are not necessarily performed in such an order, and may be performed simultaneously (in parallel) or in other orders, and these variations are within the scope of the present invention.
Further, the invention also provides a compressor fault early warning device.
Referring to fig. 2, fig. 2 is a main block diagram of a compressor fault early warning apparatus according to an embodiment of the present invention. In embodiments of the present invention, the compressor is coupled to a frequency converter, which may be configured to convert electrical energy from an input power source to output a drive current to the compressor. As shown in fig. 2, the fault early warning device for a compressor in the embodiment of the present invention mainly includes a current detection module 11 and a fault pre-judging module 12. In some embodiments, the current detection module 11 and the fault pre-determination module 12 may be combined together into one module. In some embodiments, the current detection module 11 may be configured to detect the drive current of the frequency converter in response to a received frequency converter start-up instruction. The failure pre-determination module 12 may be configured to determine whether the three-phase driving current output by the frequency converter is unbalanced according to the detected result; if so, the three-phase imbalance fault can be generated after the start of the pre-judging compressor, and in one embodiment, the description of the specific implementation function can be referred to as step S101-step S104. It should be noted that the structure of the frequency converter in the embodiment of the present invention is the same as that of the frequency converter described in the foregoing method embodiment. For brevity of description, a detailed description is omitted herein.
In one embodiment, the current detection module 11 may be further configured to perform driving current detection for each phase of bridge arm by respectively: setting a current phase bridge arm as a main phase detection bridge arm, and setting other two phase bridge arms as detected phase bridge arms; driving an upper bridge arm of a main phase detection bridge arm and a lower bridge arm of each detected phase bridge arm to be conducted according to a preset PWM signal, so that an input power supply is transmitted through a conducting loop formed by the upper bridge arm, a compressor and one lower bridge arm, and the input power supply is transmitted through a conducting loop formed by the upper bridge arm, the compressor and the other lower bridge arm; the preset PWM signal is generated according to the given value of the driving current; and collecting the actual value of the driving current transmitted on each detected phase bridge arm to obtain a current detection result of the current driving current detection. In one embodiment, the specific implementation functions may be described with reference to steps 11-13.
In one embodiment, the fault pre-determination module 12 may include a current analysis unit. The current analysis unit may be configured to perform the following operations in this embodiment: respectively judging whether currents transmitted on two detected phase bridge arms in current detection results of each driving current detection are balanced or not; if the currents transmitted on the two detected phase bridge arms in the current detection results of at least one driving current detection are unbalanced, the imbalance of the three-phase driving current output by the frequency converter is judged. In one embodiment, the description of the specific implementation function may be described with reference to step S102.
In one embodiment, the current analysis unit may be further configured to determine, for each current detection result of the driving current detection, whether currents transmitted on two detected phase legs in the current detection result are balanced by: calculating the current deviation degree of the actual value of the driving current transmitted on each detected phase bridge arm in the current detection result by adopting a deviation degree calculation function shown in the formula (1); judging whether each current deviation degree is smaller than a preset deviation degree threshold value or not; if yes, judging the current balance transmitted on the two detected phase bridge arms; if not, the unbalance of the currents transmitted on the two detected phase bridge arms is judged. In one embodiment, the specific implementation functions may be described with reference to steps 21-22.
In one embodiment, the fault pre-determination module 12 may include an imbalance calculation unit. The unbalance calculation in the present embodiment may be configured to calculate the unbalance of the three-phase driving current output by the inverter using a three-phase unbalance calculation method and based on the current detection results of the three-time driving current detection. In one embodiment, the description of the specific implementation function may be described with reference to step S105.
The foregoing compressor fault early warning device is used for executing the embodiment of the compressor fault early warning method shown in fig. 1, and the technical principles of the two embodiments, the technical problems to be solved and the technical effects to be produced are similar, and those skilled in the art can clearly understand that, for convenience and brevity of description, the specific working process and the related description of the compressor fault early warning device can refer to the description of the embodiment of the compressor fault early warning method, and will not be repeated herein.
It will be appreciated by those skilled in the art that the present invention may implement all or part of the above-described methods according to the above-described embodiments, or may be implemented by means of a computer program for instructing relevant hardware, where the computer program may be stored in a computer readable storage medium, and where the computer program may implement the steps of the above-described embodiments of the method when executed by a processor. Wherein the computer program comprises computer program code which may be in source code form, object code form, executable file or some intermediate form etc. The computer readable medium may include: any entity or device, medium, usb disk, removable hard disk, magnetic disk, optical disk, computer memory, read-only memory, random access memory, electrical carrier wave signals, telecommunications signals, software distribution media, and the like capable of carrying the computer program code. It should be noted that the computer readable medium contains content that can be appropriately scaled according to the requirements of jurisdictions in which such content is subject to legislation and patent practice, such as in certain jurisdictions in which such content is subject to legislation and patent practice, the computer readable medium does not include electrical carrier signals and telecommunication signals.
Further, it should be understood that, since the respective modules are merely set to illustrate the functional units of the apparatus of the present invention, the physical devices corresponding to the modules may be the processor itself, or a part of software in the processor, a part of hardware, or a part of a combination of software and hardware. Accordingly, the number of individual modules in the figures is merely illustrative.
Those skilled in the art will appreciate that the various modules in the apparatus may be adaptively split or combined. Such splitting or combining of specific modules does not cause the technical solution to deviate from the principle of the present invention, and therefore, the technical solution after splitting or combining falls within the protection scope of the present invention.
Thus far, the technical solution of the present invention has been described in connection with one embodiment shown in the drawings, but it is easily understood by those skilled in the art that the scope of protection of the present invention is not limited to these specific embodiments. Equivalent modifications and substitutions for related technical features may be made by those skilled in the art without departing from the principles of the present invention, and such modifications and substitutions will fall within the scope of the present invention.
Claims (6)
1. A compressor fault warning method, wherein the compressor is connected to a frequency converter configured to convert electrical energy from an input power source to output a driving current to the compressor, and the compressor is driven to operate, the method comprising:
responding to a received starting instruction of the frequency converter, and detecting the driving current of the frequency converter;
judging whether the three-phase driving current output by the frequency converter is unbalanced according to the detection result;
if yes, pre-judging that three-phase unbalance faults occur after the compressor is started and alarming;
the frequency converter comprises a three-phase full-bridge inverter, an alternating current side of the three-phase full-bridge inverter is connected with the compressor, the three-phase full-bridge inverter comprises three-phase bridge arms, each phase bridge arm comprises an upper bridge arm and a lower bridge arm, and the step of detecting the driving current of the frequency converter specifically comprises the following steps: for each phase of bridge arm, driving current detection is carried out through the following steps to obtain a current detection result of three driving current detection: setting a current phase bridge arm as a main phase detection bridge arm, and setting other two phase bridge arms as detected phase bridge arms; driving an upper bridge arm of the main phase detection bridge arm and a lower bridge arm of each detected phase bridge arm to be conducted according to a preset PWM signal, so that the input power supply is transmitted through a conducting loop formed by the upper bridge arm, the compressor and one lower bridge arm, and the input power supply is transmitted through a conducting loop formed by the upper bridge arm, the compressor and the other lower bridge arm; wherein the preset PWM signal is a PWM signal generated according to a given value of the driving current; collecting the actual value of the driving current transmitted on each detected phase bridge arm to obtain a current detection result of the current driving current detection;
the step of judging whether the three-phase driving current output by the frequency converter is unbalanced according to the detection result specifically comprises the following steps: respectively judging whether currents transmitted on two detected phase bridge arms in current detection results of each driving current detection are balanced or not; if the currents transmitted on the two detected phase bridge arms in the current detection results of at least one driving current detection are unbalanced, the imbalance of the three-phase driving current output by the frequency converter is judged.
2. The compressor fault warning method according to claim 1, wherein the step of "determining whether currents transmitted on two detected phase legs are balanced in current detection results of each driving current detection" specifically includes:
for the current detection result of each driving current detection, judging whether currents transmitted on two detected phase bridge arms in the current detection result are balanced or not through the following steps:
and respectively calculating the current deviation degree of the actual value of the driving current transmitted on each detected phase bridge arm in the current detection result by adopting a deviation degree calculation function shown as follows:
wherein d represents the current deviation degree, I r Representing the actual value of the driving current, wherein I represents the given value of the driving current;
judging whether each current deviation degree is smaller than a preset deviation degree threshold value or not;
if yes, judging the current balance transmitted on the two detected phase bridge arms; if not, the unbalance of the currents transmitted on the two detected phase bridge arms is judged.
3. The compressor fault warning method according to claim 2, wherein after the step of "determining that the three-phase driving current outputted from the inverter is unbalanced", the method further comprises:
and calculating the unbalance of the three-phase driving current output by the frequency converter according to the current detection result of the three-time driving current detection by adopting a three-phase unbalance calculation method.
4. A compressor fault warning device, wherein the compressor is connected to a frequency converter configured to convert electrical energy from an input power source to output a driving current to the compressor, and the compressor is driven to operate, the device comprising:
a current detection module configured to detect a drive current for the frequency converter in response to a received frequency converter start instruction;
a failure pre-judging module configured to judge whether the three-phase driving current output by the frequency converter is unbalanced according to the detected result; if yes, pre-judging that three-phase unbalance faults occur after the compressor is started and alarming;
the frequency converter comprises a three-phase full-bridge inverter, an alternating current side of the three-phase full-bridge inverter is connected with the compressor, the three-phase full-bridge inverter comprises three-phase bridge arms, each phase bridge arm comprises an upper bridge arm and a lower bridge arm, and the current detection module is further configured to detect driving current of each phase bridge arm through the following steps respectively to obtain a current detection result of three driving current detection: setting a current phase bridge arm as a main phase detection bridge arm, and setting other two phase bridge arms as detected phase bridge arms; driving an upper bridge arm of the main phase detection bridge arm and a lower bridge arm of each detected phase bridge arm to be conducted according to a preset PWM signal, so that the input power supply is transmitted through a conducting loop formed by the upper bridge arm, the compressor and one lower bridge arm, and the input power supply is transmitted through a conducting loop formed by the upper bridge arm, the compressor and the other lower bridge arm; wherein the preset PWM signal is a PWM signal generated according to a given value of the driving current; collecting the actual value of the driving current transmitted on each detected phase bridge arm to obtain a current detection result of the current driving current detection;
the fault pre-determination module includes a current analysis unit configured to perform the following operations: respectively judging whether currents transmitted on two detected phase bridge arms in current detection results of each driving current detection are balanced or not; if the currents transmitted on the two detected phase bridge arms in the current detection results of at least one driving current detection are unbalanced, the imbalance of the three-phase driving current output by the frequency converter is judged.
5. The compressor fault warning device of claim 4, wherein the current analysis unit is further configured to:
for the current detection result of each driving current detection, judging whether currents transmitted on two detected phase bridge arms in the current detection result are balanced or not through the following steps:
and respectively calculating the current deviation degree of the actual value of the driving current transmitted on each detected phase bridge arm in the current detection result by adopting a deviation degree calculation function shown as follows:
wherein d represents the current deviation degree, I r Representing the actual value of the driving current, wherein I represents the given value of the driving current;
judging whether each current deviation degree is smaller than a preset deviation degree threshold value or not;
if yes, judging the current balance transmitted on the two detected phase bridge arms; if not, the unbalance of the currents transmitted on the two detected phase bridge arms is judged.
6. The compressor fault pre-warning device according to claim 5, wherein the fault pre-judgment module includes an unbalance calculation unit configured to calculate the unbalance of the three-phase driving current outputted from the inverter by using a three-phase unbalance calculation method and based on a current detection result of three driving current detection.
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