CN114039513B - Judgment method and judgment system for forward and reverse wind of fan - Google Patents
Judgment method and judgment system for forward and reverse wind of fan Download PDFInfo
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- CN114039513B CN114039513B CN202111331557.XA CN202111331557A CN114039513B CN 114039513 B CN114039513 B CN 114039513B CN 202111331557 A CN202111331557 A CN 202111331557A CN 114039513 B CN114039513 B CN 114039513B
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- 238000000034 method Methods 0.000 title claims abstract description 29
- 238000005070 sampling Methods 0.000 claims abstract description 29
- 238000010248 power generation Methods 0.000 claims abstract description 13
- 238000004364 calculation method Methods 0.000 claims description 17
- 238000012952 Resampling Methods 0.000 claims description 5
- 238000004804 winding Methods 0.000 claims description 3
- 238000001514 detection method Methods 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 238000004088 simulation Methods 0.000 description 1
- 230000003068 static effect Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P1/00—Arrangements for starting electric motors or dynamo-electric converters
- H02P1/02—Details
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/34—Testing dynamo-electric machines
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
- H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
- H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters
- H02P27/08—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation
Abstract
The invention relates to a method and a system for judging the forward and reverse wind direction of a fan, comprising the following steps: the phase A, phase B and phase C lower bridge power switches are respectively conducted, and the differential pressure of the phase A, phase B and phase C is obtained through collecting power switch Guan Louji and the source electrode, so as to obtain the current; obtaining the motor rotor angle theta according to the current magnitude 1 A current peak value K; obtaining a motor power generation constant and a counter electromotive force constant, and calculating according to the motor power generation constant and the counter electromotive force constant to obtain the estimated angular frequency w 1 The method comprises the steps of carrying out a first treatment on the surface of the By estimating the angular frequency w 1 Determining sampling interval time of the bridge power switch under the phase A, the phase B and the phase C which are conducted again; when the sampling interval time is up, the phase A, phase B and phase C lower bridge power switches are conducted again, the differential pressure of the phase A, phase B and phase C is obtained again, and the current angle theta is calculated again 2 According to theta 1 ，θ 2 Accurate estimation of angular frequencies w and θ at sampling time 1 ，θ 2 The magnitude relation obtains the forward and reverse wind directions. The method avoids externally overlapping a circuit, reduces hardware cost and simplifies a motor control circuit.
Description
Technical Field
The invention belongs to the technical field of air conditioner fans, and particularly relates to a method for judging forward and reverse directions of a fan.
Background
With the development of science and technology and the progress of society, people have higher and higher demands for substances, air conditioners have higher and higher popularity in domestic markets, and people have higher and higher demands for air conditioners in summer and winter. The problem of stable starting of a fan in an air conditioner external unit is always one of core technologies which are important to overcome by air conditioner manufacturers, and is also an important standard for measuring the quality of the air conditioner external unit.
The common air conditioner external unit is hung outdoors, the fan in the external unit is not kept in a static state under the influence of natural wind, if the fan rotates under the influence of natural wind, the initial angle of a rotor is identified through a normal starting method, the fan is suddenly stopped and generates great vibration, so that the real-time state of downwind rotation needs to be observed in advance, and once the accurate rotor angle is detected, the fan is switched to a closed-loop starting program, and the air conditioner is started immediately. The traditional solution method is a back electromotive force detection method, and the rotation speed and the angle are judged by a method of acquiring the voltage of a motor end to acquire the back electromotive force, but the back electromotive force detection method needs an externally-mounted circuit, and three resistance simulation neutral points are externally connected on a three-phase line to accurately detect the phase voltage, so that the method has a complex structure and is overlarge in cost.
Disclosure of Invention
In order to solve the problems, the invention provides a method for judging whether a fan runs in the upwind direction, which utilizes the principle that a motor works in a power generation state under the influence of natural wind, obtains the rotating speed and the angular velocity by detecting current, and switches to a closed-loop starting program to realize the stable starting of an air conditioner.
In order to achieve the above purpose, the invention is realized by the following technical scheme:
the invention provides a method for judging the forward and reverse wind of a fan, which is characterized in that the rotating speed and the angular speed are obtained by detecting the current, the forward and reverse wind state of the fan is obtained by positive and negative angular speeds, and then the fan is switched to a closed-loop starting program, so that the problem of stable starting of the fan of an air conditioner under the influence of natural wind is solved.
The specific judging method comprises the following steps:
step 1: the three-phase lower bridge power switches are respectively and sequentially conducted, three-phase differential pressure is obtained by collecting power switches Guan Louji and sources, currents are respectively obtained, and the calculation formula of the current is as follows: current = differential voltage/internal resistance of the power switch.
Step 2: obtaining the motor rotor angle theta according to the magnitude of the current 1 And a current peak value K, the calculation formula is as follows:
step 3: obtaining motor power generation constant and counter electromotive force constant, and calculating according to the motor power generation constant and the counter electromotive force constant to obtain the pre-powerEstimate angular frequency w 1 ，w 1 By the formulaCalculated, wherein K is the current peak value reflecting the power generation capacity, K e Is the back emf constant.
Step 4: by estimating the angular frequency w 1 Determining sampling interval time of a re-conduction three-phase lower bridge power switch; in order to avoid that sampling current value changes too small caused by too short resampling time interval and the sampling current value changes too long time interval to cause that the sampling of the current exceeds the period sampling to be invalid, the resampling time interval is set to be T/2-T in order to obtain accurate effective current value.
Step 5: when the sampling interval time is up, the three-phase lower bridge power switch is conducted again, the three-phase differential pressure is obtained, and the current motor rotor angle theta is obtained through calculation 2 According to the angle theta of the motor rotor 1 Current motor rotor angle θ 2 Accurate estimation of angular frequencies w and θ at sampling time 1 ，θ 2 The magnitude relation obtains the forward and reverse wind directions.
Preferably: θ 1 And theta 2 According to the formulaWhen the angular frequency w is more than 0, judging that the air conditioner is in a downwind state, and sending the current speed to a closed-loop starting program to start the air conditioner; when the angular frequency w is less than 0, judging that the air conditioner is in an upwind state, executing a closed-loop starting program after entering a braking state, and starting the air conditioner.
The invention also discloses a fan forward and reverse wind judging method system, which comprises a motor, an inverter, a driving unit, a controller, a voltage sampling unit, a current calculating unit, an angle observer and a comparator; the controller is respectively connected with the comparator module and the driving unit, the driving unit is respectively connected with the inverter module, the inverter module is respectively connected with the three-phase stator winding of the motor, the voltage sampling unit is connected with the inverter and the current calculation unit, the current calculation unit is respectively connected with the angle observer, the angle observer is respectively connected with the comparator, and the comparator is respectively connected with the controller and is used for comparing the angle difference twice so as to judge the direction along the upwind.
The beneficial effects of the invention are as follows:
1. the method changes the traditional method of obtaining rotor position information by detecting phase voltage, obtains a current value by detecting current so as to obtain the angular speed and the rotating speed of the rotor, and obtains the forward and reverse wind state of the fan by judging the positive and negative of the angular frequency w of the rotor so as to stably start the air conditioner.
2. The invention optimizes sampling time selection, avoids the phenomenon of ringing which is current oscillation generated when the power switch is switched, and the controller sends PWM waves to the power switch to generate time delay.
Drawings
FIG. 1 is a flow chart of a method for judging whether a fan is running upwind in an embodiment of the invention.
Fig. 2 is a circuit diagram of a method for judging whether a fan is running in the upwind direction in an embodiment of the invention.
FIG. 3 is a system diagram of a method for judging whether a fan is running upwind in an embodiment of the invention.
Detailed Description
Embodiments of the invention are disclosed in the drawings, and for purposes of explanation, numerous practical details are set forth in the following description. However, it should be understood that these practical details are not to be taken as limiting the invention. That is, in some embodiments of the invention, these practical details are unnecessary. Moreover, for the purpose of simplifying the drawings, some conventional structures and components are shown in the drawings in a simplified schematic manner.
The invention provides a method for judging whether a fan rotates in the forward and reverse directions, when the fan rotates under the influence of natural wind and a motor is in a power generation state, a flow chart of the method is shown in figure 1, and the method comprises the following steps:
step 1: the three-phase lower bridge power switches are respectively and sequentially conducted, three-phase differential pressure is obtained by collecting power switches Guan Louji and sources, currents are respectively obtained, and the calculation formula of the current is as follows: current = differential voltage/internal resistance of the power switch.
Step 2: obtaining the motor rotor angle theta according to the magnitude of the current 1 And a current peak value K, the calculation formula is as follows:
the angle theta of the motor rotor can be obtained after the expansion 1 And the magnitude of the current peak K.
Step 3: obtaining a motor power generation constant and a counter electromotive force constant, and calculating according to the motor power generation constant and the counter electromotive force constant to obtain the estimated angular frequency w 1 ，w 1 By the formulaCalculated, wherein K is the current peak value reflecting the power generation capacity, K e Is the back emf constant.
Step 4: by estimating the angular frequency w 1 Determining sampling interval time of a re-conduction three-phase lower bridge power switch; in order to avoid that sampling current value changes too small caused by too short resampling time interval and the sampling current value changes too long time interval to cause that the sampling of the current exceeds the period sampling to be invalid, the resampling time interval is set to be T/2-T in order to obtain accurate effective current value.
Step 5: when the sampling interval time is up, the three-phase lower bridge power switch is conducted again, the three-phase differential pressure is obtained, and the current motor rotor angle theta is obtained through calculation 2 According to the angle theta of the motor rotor 1 Current motor rotor angle θ 2 Accurate estimation of angular frequencies w and θ at sampling time 1 ，θ 2 The magnitude relation obtains the direction of the forward and reverse wind, theta 1 And theta 2 According to the formulaWhen the angular frequency w is less than 0, judging that the air conditioner is in a downwind state, and sending the current speed to a closed-loop starting program to start the air conditioner;when the angular frequency w is less than 0, judging that the air conditioner is in an upwind state, executing a closed-loop starting program after entering a braking state, and starting the air conditioner.
The invention provides a fan forward and reverse wind judging system, as shown in figure 3, comprising: a motor, an inverter 51, a driving unit 52, a controller 53, a voltage sampling unit 54, a current calculation unit 55, an angle observer 56, and a comparator 57;
the controller 53 is respectively connected with the comparator module 57 and the driving unit 52, and is used for analyzing the processed data and then selecting a motor operation mode;
the driving unit 52 is respectively connected with the controller 53 and the inverter module 51, and is used for selecting a PWM working mode;
the inverter module 51 is respectively connected with the driving unit 52 and the motor three-phase stator winding, and is used for starting and maintaining the normal operation of the motor and controlling the motor operation mode according to the instruction sent by the controller 53;
the voltage sampling unit 54 is respectively connected with the inverter 51 and the current calculating unit 55, and is used for obtaining three-phase voltages;
the current calculation unit 55 is respectively connected with the voltage sampling unit 54 and the angle observer 56 and is used for calculating and obtaining the current;
the angle observer 56 is respectively connected with the current calculation unit 55 and the comparator 57, and is used for obtaining the current angle through current magnitude calculation;
the comparator 57 is connected to the angle observer 56 and the controller 53, respectively, and is configured to compare the angle difference twice to determine the forward and reverse wind directions.
The method avoids externally overlapping circuits, reduces hardware cost and simplifies a motor control circuit.
The foregoing description is only illustrative of the invention and is not to be construed as limiting the invention. Various modifications and variations of the present invention will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement, or the like, which is within the spirit and principles of the present invention, should be included in the scope of the claims of the present invention.
Claims (4)
1. A method for judging forward and backward wind of a fan is characterized by comprising the following steps of: the judging method comprises the following steps:
step 1: the power switches of the lower bridge of the phase A, the phase B and the phase C are respectively and sequentially conducted, the power switch Guan Louji is collected, the source electrode obtains A, B, C three-phase differential pressure, and currents IA, IB and IC are respectively obtained;
step 2: obtaining the motor rotor angle theta according to the current obtained in the step 1 1 A current peak value K;
step 3: obtaining a motor power generation constant and a counter electromotive force constant, and calculating according to the motor power generation constant and the counter electromotive force constant to obtain the estimated angular frequency w 1 ；
Step 4: the estimated angular frequency w obtained by the step 3 1 Determining sampling interval time of the bridge power switch under the phase A, the phase B and the phase C which are conducted again;
step 5: when the sampling interval time is up, the phase A, phase B and phase C lower bridge power switches are conducted again, the differential pressure of A, B, C three phases is obtained, and the current motor rotor angle theta is obtained through calculation 2 According to the angle theta of the motor rotor 1 Current motor rotor angle θ 2 And the sampling time accurately estimates the angular frequency w, and obtains the forward and reverse wind directions according to the magnitude relation of the angular frequency w,
in the step 5, the angular frequency w is equal to the motor rotor angle θ obtained in the step 2 1 And step 5, obtaining the current motor rotor angle theta 2 According to the formulaWhen the angular frequency w is more than 0, judging that the air conditioner is in a downwind state, and sending the current speed to a closed-loop starting program to start the air conditioner; when the angular frequency w is less than 0, judging that the air conditioner is in an upwind state, executing a closed-loop starting program after entering a braking state, starting the air conditioner,
wherein: in the step 4, the resampling interval time is set to be T/2-T,
wherein in the step 3, the estimated angular frequency w 1 By the formulaCalculated, wherein K is the current peak value reflecting the power generation capacity, K e Is the back emf constant.
2. The method for judging whether the fan is upwind according to claim 1, wherein the method comprises the following steps of: in said step 2, the motor rotor angle θ 1 The calculation formula of the current peak value K is as follows:
after expansion, the angle theta of the motor rotor is obtained 1 And the magnitude of the current peak K.
3. The method for judging whether the fan is upwind according to claim 1, wherein the method comprises the following steps of: the calculation formula of the current in the step 1 is as follows: current = differential voltage/internal resistance of the power switch.
4. The fan upwind judgment system according to claim 1, wherein: the system comprises a motor, an inverter, a driving unit, a controller, a voltage sampling unit, a current calculating unit, an angle observer and a comparator;
the controller is respectively connected with the comparator module and the driving unit and is used for analyzing the processed data and then selecting a motor operation mode;
the driving unit is respectively connected with the controller and the inverter module and is used for selecting a PWM working mode;
the inverter module is respectively connected with the driving unit and the three-phase stator winding of the motor, is used for starting and maintaining the normal operation of the motor, and controls the operation mode of the motor according to the instruction sent by the controller;
the voltage sampling unit is connected with the inverter and the current calculating unit and is used for obtaining three-phase voltages;
the current calculation unit is respectively connected with the voltage sampling unit and the angle observer and is used for calculating and obtaining the current;
the angle observer is respectively connected with the current calculation unit and the comparator and is used for calculating the current angle through the current magnitude;
the comparator is respectively connected with the angle observer and the controller and is used for comparing the angle difference twice so as to judge the forward and reverse wind directions.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202111331557.XA CN114039513B (en) | 2021-11-11 | 2021-11-11 | Judgment method and judgment system for forward and reverse wind of fan |
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| CN202111331557.XA CN114039513B (en) | 2021-11-11 | 2021-11-11 | Judgment method and judgment system for forward and reverse wind of fan |
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| CN114039513B true CN114039513B (en) | 2023-12-19 |
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| CN115441802B (en) * | 2022-09-06 | 2023-12-01 | 江苏新安电器股份有限公司 | Software method for detecting and starting motor in forward and reverse directions |
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| ITBO20110340A1 (en) * | 2011-06-13 | 2012-12-14 | Spal Automotive Srl | ELECTRIC DRIVE |
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