Method and system for detecting the rotational direction of the magnetic field of an ac motor

Abstract

The application discloses a kind of detecting the method and system of alternating current motor stator magnetic field rotation direction, comprising the following steps: S1, using constant current source to inject regular change current to the measured stator, when current flows through the measured stator, magnetic field will be generated in the measured stator inside, when current regular change on the measured stator, magnetic field generated in the measured stator unit also regular change, mainly reflect on the magnetic field intensity variation and the direction change of magnetic induction line.This application provides technical scheme, using constant current source unit to inject regular change current to the measured stator unit, simultaneously through magnetic field sensing unit and acquisition loop unit, obtain the magnetic field data of multiple time points, through the magnetic field rotation direction algorithm of micro control unit, the magnetic field of stator is positive rotation, reverse or and abnormality is automatically calculated.

Description

Technical Field

[0001] This invention relates to the field of motor testing technology, specifically to a method and system for detecting the rotation direction of the stator magnetic field of an AC motor. Background Technology

[0002] The direction of the magnetic field of the motor stator determines the direction of the motor's magnetic field. When the direction of the motor stator's magnetic field is incorrect, the direction of the motor's rotation will also be incorrect. Detecting the rotation direction of the AC motor stator's magnetic field is a routine test for AC motors. Existing technologies typically use the following methods to detect the rotation direction of the AC motor stator: First, after the motor is manufactured, power is supplied to the motor, and the direction of rotation is determined by observing the motor rotor. Second, a specific rotor is used to detect the direction of the stator's magnetic field. After the stator is manufactured, a rotor is installed into the stator using specific tooling, and then three-phase AC power is supplied to the motor. The stator rotation direction is indirectly determined by observing the direction of rotation of the rotor.

[0003] The first detection method omits the determination of stator rotation direction during the stator production stage. After the motor production process is completed, the stator rotation direction is indirectly determined by the actual rotation direction of the motor. Therefore, if an error in stator rotation direction is detected, the rework cost will increase. The second detection method has the disadvantage of inconvenient rotor installation and the need to prepare specific rotors and tooling for different stator sizes. In summary, the traditional AC motor stator rotation direction testing method has the problems of cumbersome testing process, high rework cost, and large amount of material preparation. Summary of the Invention

[0004] The purpose of this invention is to provide a method and system for detecting the rotation direction of the stator magnetic field of an AC motor, so as to solve the problems mentioned in the background art.

[0005] 1. To achieve the above objectives, the present invention provides the following technical solution: a method for detecting the rotation direction of the stator magnetic field of an AC motor, comprising the following steps:

[0006] S1. A constant current source is used to inject a regularly changing current into the measured quanta. When current flows through the measured quanta, a magnetic field is generated inside the measured quanta. When the current on the measured quanta changes regularly, the magnetic field generated inside the measured quanta unit also changes regularly, mainly reflecting the changes in the strength of the magnetic field and the direction of the magnetic field lines.

[0007] S2. Under the excitation of a constant DC current, the strength and direction of the magnetic field at any point inside the measured quanta will remain constant. When the measured quanta change regularly under a constant DC current, the strength and direction of the magnetic field at any point inside the measured quanta will also change regularly. The magnetic field strength value can be measured by arbitrarily selecting a magnetic field measurement point.

[0008] S3. The magnetic field strength value is measured by a magnetic field sensor consisting of two magnetic field sensors with an included angle of 90°. Based on the obtained magnetic field strength value, the direction of the magnetic field at the current point can be calculated using trigonometric functions and vectors.

[0009] S4. Magnetic field data at multiple time points are acquired through magnetic field sensing and acquisition circuits. The magnetic field direction of the AC motor stator is calculated by the system that detects the direction of rotation of the stator magnetic field to determine whether the magnetic field of the measured stator is rotating forward, backward, or abnormal.

[0010] A system for detecting the rotation direction of the stator magnetic field of an AC motor includes an input circuit unit, a microcontroller unit, a power supply unit, a constant current source unit, a switching circuit unit, a stator to be measured, a magnetic field sensing unit, a data acquisition circuit unit, a conversion circuit unit, and an output circuit unit.

[0011] An input loop unit is used to transmit externally input signals to a microcontroller unit.

[0012] The microcontroller unit receives signals from the input circuit unit and uses them to control the operation and start-up of the AC motor stator magnetic field rotation device, and transmits the control signals to the switching circuit unit.

[0013] The switching circuit unit receives signals from the microcontroller unit and simultaneously sends the DC power from the constant current source unit to the measured subunit to generate a magnetic field in the measured subunit, and sends the acquired signal from the magnetic field sensing unit to the acquisition circuit unit.

[0014] The measured sub-unit receives the DC power emitted by the switching loop unit, and the received DC power is used to excite the measured sub-unit to generate a constant electromagnetic field.

[0015] The magnetic field sensing unit receives the data signal sent by the switching circuit unit and uses it to acquire the magnetic field signal inside the product under test, converts the magnetic field signal into a voltage signal, and transmits the voltage signal to the acquisition circuit unit.

[0016] The acquisition loop unit receives the voltage signal emitted by the magnetic field sensing unit and transmits the voltage signal into the conversion loop unit.

[0017] The conversion circuit unit receives the voltage signal emitted by the acquisition circuit unit, converts the voltage signal into a digital signal, and transmits the digital signal to the microcontroller unit.

[0018] The output circuit unit receives the control signals sent by the microcontroller unit and converts the control signals output by the microcontroller unit into test results of the AC motor stator magnetic field rotation device.

[0019] Preferably, the transmitter of the input loop unit is electrically connected to the receiver of the microcontroller unit, the transmitter of the microcontroller unit is electrically connected to the receiver of the switching loop unit, the transmitter of the switching loop unit is simultaneously electrically connected to the receivers of the magnetic field sensing unit and the measured subunit, the transmitter of the magnetic field sensing unit is electrically connected to the receiver of the acquisition loop unit, the transmitter of the acquisition loop unit is electrically connected to the receiver of the conversion loop unit, the transmitter of the conversion loop unit is electrically connected to the receiver of the microcontroller unit, and the transmitter of the microcontroller unit is electrically connected to the receiver of the output loop unit.

[0020] Preferably, the transmitting end of the power supply unit is electrically connected to the receiving end of both the microcontroller unit and the constant current source unit. The power supply unit is used to supply power to the microcontroller unit and to provide the constant current source unit as an excitation power input. The transmitting end of the constant current source unit is connected to the receiving end of the switching circuit unit. The constant current source unit is used to excite the measured subunit to generate a constant electromagnetic field.

[0021] Preferably, the constant current source unit injects a regularly changing current into the stator unit under test, and at the same time, it acquires magnetic field data at multiple time points through the magnetic field sensing unit and the acquisition circuit unit. Through the magnetic field rotation algorithm of the microcontroller unit, it automatically calculates whether the magnetic field of the stator is rotating forward, reverse, or abnormal.

[0022] Preferably, the input loop unit includes an external input module, a signal translation module, and an internal signal output module. The external input module is composed of a button or an external input device, which transmits external input information to the signal translation module. The signal translation module receives the external input information sent by the external input module, translates the received external input information into an internal signal, and transmits the internal signal to the internal signal output module. The internal signal output module receives the internal signal sent by the signal translation module and transmits the received internal signal to a designated module.

[0023] Preferably, the transmitting end of the external input module is electrically connected to the receiving end of the signal translation module, and the transmitting end of the signal translation module is electrically connected to the receiving end of the internal signal output module.

[0024] Preferably, the microcontroller unit includes a signal input module, a logic processing module, an external processing module, and an internal processing module. The signal input module transmits the integrated signals from the conversion loop unit and the input loop unit to the logic processing module. The logic processing module divides the integrated signals into external signals and internal signals. The external signals are signals input through an external input device, and the internal signals are signals generated by the internal modules during operation. The external signals are transmitted to the external processing module, and the internal signals are transmitted to the internal processing module.

[0025] Preferably, the microcontroller further includes a control signal output module. The external processing module interprets and translates the external signals into corresponding external control signals and transmits them to the control signal output module. The internal processing module uses a magnetic field rotation algorithm to automatically calculate whether the stator's magnetic field is rotating forward, backward, or abnormal based on the internal signals, and transmits the calculated control signals to the control information output module. The control signal output module transmits the received signals to the switching loop unit.

[0026] Preferably, the transmitting end of the information input module is electrically connected to the logic processing module, the transmitting end of the logic processing module is electrically connected to the receiving ends of both the internal processing module and the external processing module, and the transmitting ends of both the internal processing module and the external processing module are electrically connected to the receiving end of the control signal output module.

[0027] Preferably, the acquisition loop unit includes current acquisition modules for each channel, a loop anomaly judgment module, a warning judgment module, a loop protection module, and a signal transmission module. The current acquisition modules for each channel are used to acquire current signals for each channel and transmit the current signals to the loop anomaly judgment module. The loop anomaly judgment module uses the current signals to determine whether there is an anomaly. The judgment condition is whether the current is lost or unbalanced. If there is no anomaly, the current signal is transmitted to the signal transmission module. If there is an anomaly, the current signal is transmitted to the loop protection module. The signal transmission module converts the current signal into an acquisition signal and transmits it to the warning judgment module. The loop protection module locates the abnormal loop position based on the current signal and performs lockout protection on the abnormal loop, and sends an anomaly signal to the warning sending module.

[0028] Preferably, the acquisition loop unit further includes a warning issuing module, an anomaly handling module, and an acquisition signal output module. The warning issuing module receives the anomaly signal issued by the loop protection module and issues an alarm signal to the warning judgment module. The warning judgment module judges the received signal based on whether an alarm signal has been received. If an alarm signal is received, it transmits the alarm signal to the anomaly handling module. If no alarm signal is received, it transmits the received acquisition signal to the acquisition signal output module. The anomaly handling module processes the abnormal circuit according to the alarm signal. The acquisition signal output module outputs the acquisition signal to the conversion loop unit.

[0029] Preferably, the transmitting end of each current acquisition module is electrically connected to the receiving end of the warning judgment module; the transmitting end of the warning judgment module is also electrically connected to the receiving ends of the loop protection module and the signal acquisition transmission module; the transmitting end of the loop protection module is electrically connected to the receiving end of the warning issuing module; the transmitting ends of the warning issuing module and the signal acquisition transmission module are also electrically connected to the receiving end of the loop anomaly judgment module; and the transmitting end of the loop anomaly judgment module is also electrically connected to the receiving ends of the anomaly processing module and the signal acquisition output module.

[0030] Preferably, the magnetic field sensing unit includes a vertical magnetic field sensor and a horizontal magnetic field sensor. The vertical magnetic field sensor measures the magnetic field signal in the horizontal direction and converts the magnetic field signal into a voltage signal. The horizontal magnetic field sensor measures the magnetic field signal in the horizontal direction and converts the magnetic field signal into a voltage signal.

[0031] This invention provides a method for detecting the rotation direction of the stator magnetic field of an AC motor. Compared with the prior art, the advantages of this invention are:

[0032] By injecting a regularly changing current into the stator unit under test through a constant current source unit, and simultaneously acquiring magnetic field data at multiple time points through a magnetic field sensing unit and a data acquisition circuit unit, the magnetic field rotation algorithm of the microcontroller unit automatically calculates whether the stator's magnetic field is rotating forward, backward, or abnormal. This solves the problems of cumbersome testing process, high rework costs, and large amounts of material preparation required by traditional stator rotation testing methods. Attached Figure Description

[0033] Figure 1 This is a system principle block diagram for detecting the rotation direction of the stator magnetic field of an AC motor according to the present invention;

[0034] Figure 2 This is a block diagram of the microcontroller unit of the present invention;

[0035] Figure 3 This is a block diagram of the acquisition loop unit of the present invention;

[0036] Figure 4 This is a block diagram of the input circuit unit of the present invention;

[0037] Figure 5 This is a graph showing the current variation of the measured sub-unit in this invention;

[0038] Figure 6 This is a circuit schematic diagram of the constant current source unit of the present invention;

[0039] Figure 7 This is the magnetic field pattern of the subunit being measured in this invention;

[0040] Figure 8 This is a diagram showing the composition of the magnetic field sensing unit of the present invention;

[0041] Figure 9 This is a pattern of the magnetic field of the horizontal magnetic field sensor of the present invention.

[0042] Figure 10 This is a graph showing the relationship between the magnetic field strength of the horizontal sensor and the output voltage of the present invention.

[0043] Figure 11 This is a diagram showing the magnetic field direction and intensity at different times for the synthetic vector AB of this invention.

[0044] Figure 12 This is a diagram showing the change in magnetic field direction at different times according to the present invention.

[0045] In the diagram: 1. Input circuit unit; 2. Microcontroller unit; 3. Power supply unit; 4. Constant current source unit; 5. Switching circuit unit; 6. Conversion circuit unit; 7. Acquisition circuit unit; 8. Magnetic field sensing unit; 9. Measured sub-unit; 10. Output circuit unit; 11. Magnetic field; 12. Vertical magnetic field sensor; 13. Horizontal magnetic field sensor; 14. Composite vector AB; 15. Magnetic field direction change law; 16. Stator winding. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] Example 1:

[0048] 2. Please refer to Figure 1-4 This invention provides a technical method: a method for detecting the rotation direction of the stator magnetic field of an AC motor, comprising the following steps:

[0049] S1. A constant current source is used to inject a regularly changing current into the measured quanta. When current flows through the measured quanta, a magnetic field is generated inside the measured quanta. When the current on the measured quanta changes regularly, the magnetic field generated inside the measured quanta unit also changes regularly, mainly reflecting the changes in the strength of the magnetic field and the direction of the magnetic field lines.

[0050] S2. Under the excitation of a constant DC current, the strength and direction of the magnetic field at any point inside the measured quanta will remain constant. When the measured quanta change regularly under a constant DC current, the strength and direction of the magnetic field at any point inside the measured quanta will also change regularly. The magnetic field strength value can be measured by arbitrarily selecting a magnetic field measurement point.

[0051] S3. The magnetic field strength value is measured by a magnetic field sensor consisting of two magnetic field sensors with an included angle of 90°. Based on the obtained magnetic field strength value, the direction of the magnetic field at the current point can be calculated using trigonometric functions and vectors.

[0052] S4. Magnetic field data at multiple time points are acquired through magnetic field sensing and acquisition circuits. The magnetic field direction of the AC motor stator is calculated by the system that detects the direction of rotation of the stator magnetic field to determine whether the magnetic field of the measured stator is rotating forward, backward, or abnormal.

[0053] A system for detecting the rotation direction of the stator magnetic field of an AC motor includes an input circuit unit 1, a microcontroller unit 2, a power supply unit 3, a constant current source unit 4, a switching circuit unit 5, a measured stator unit 9, a magnetic field sensing unit 8, a data acquisition circuit unit 7, a conversion circuit unit 6, and an output circuit unit 10.

[0054] Input loop unit 1 is used to transmit externally input signals to microcontroller unit 2;

[0055] The microcontroller unit 2 receives the signal from the input circuit unit 1 and uses it to control the operation and start-up of the AC motor stator magnetic field rotation device, and transmits the control signal to the switching circuit unit 5.

[0056] The switching circuit unit 5 receives the signal sent by the microcontroller unit 2 and simultaneously sends the DC power from the constant current source unit 4 to the measured sub-unit 9 to generate a magnetic field in the measured sub-unit 9, and sends the acquisition signal from the magnetic field sensing unit 8 to the acquisition circuit unit 7.

[0057] The measured sub-unit 9 receives the DC power emitted by the switching circuit unit 5, and the received DC power is used to generate a magnetic field signal in the measured sub-unit 9.

[0058] The magnetic field sensing unit 8 receives the data signal sent by the switching circuit unit 5 and is used to acquire the magnetic field signal inside the product under test, convert the magnetic field signal into a voltage signal, and transmit the voltage signal to the acquisition circuit unit 7.

[0059] The acquisition loop unit 7 receives the voltage signal emitted by the magnetic field sensing unit 8 and transmits the voltage signal into the conversion loop unit 6.

[0060] The conversion circuit unit 6 receives the voltage signal emitted by the acquisition circuit unit 7, converts the voltage signal into a digital signal, and transmits the digital signal to the microcontroller unit 2.

[0061] The output circuit unit 10 receives the control signal sent by the microcontroller unit 2 and converts the control signal output by the microcontroller unit 2 into the test result of the AC motor stator magnetic field rotation device.

[0062] The transmitter of input loop unit 1 is electrically connected to the receiver of microcontroller unit 2. The transmitter of microcontroller unit 2 is electrically connected to the receiver of conversion loop unit 6. The transmitter of conversion loop unit 6 is also electrically connected to the receivers of magnetic field sensing unit 8 and measured subunit 9. The transmitter of magnetic field sensing unit 8 is electrically connected to the receiver of acquisition loop unit 7. The transmitter of acquisition loop unit 7 is electrically connected to the receiver of conversion loop unit 6. The transmitter of conversion loop unit 6 is electrically connected to the receiver of microcontroller unit 2. The transmitter of microcontroller unit 2 is electrically connected to the receiver of output loop unit 10. In this way, the accuracy of signal propagation is ensured through the electrical connection of each unit.

[0063] The transmitter of the power supply unit 3 is electrically connected to the receivers of the microcontroller unit 2 and the constant current source unit 4, respectively. The power supply unit 3 is used to supply power to the microcontroller unit 2 and to provide the constant current source unit 4 as an excitation power input. The transmitter of the constant current source unit 4 is connected to the receiver of the switching circuit unit 5. The constant current source unit 4 is used to excite the measured subunit 9 to generate a constant electromagnetic field. In this way, the device can operate for a long time through the power supply unit 3 and the constant current source unit 4.

[0064] The constant current source unit 4 injects a regularly changing current into the measured sub-unit 9. At the same time, the magnetic field data at multiple time points are acquired through the magnetic field sensing unit 8 and the acquisition circuit unit 7. Through the magnetic field rotation algorithm of the microcontroller unit 2, the magnetic field of the stator is automatically calculated to determine whether it is rotating forward, backward, or abnormal, thus realizing the ability to quickly and accurately detect the rotation direction of the stator magnetic field of the AC motor.

[0065] The input loop unit 1 includes an external input module, a signal translation module, and an internal signal output module. The external input module consists of buttons or external input devices, which transmit external input information to the signal translation module. The signal translation module receives the external input information from the external input module, translates the received external input information into an internal signal, and transmits the internal signal to the internal signal output module. The internal signal output module receives the internal signal from the signal translation module and transmits the received internal signal to the designated module. Through the external input of the input loop unit 1, accurate reception and transmission of external signals are achieved.

[0066] The transmitter of the external input module is electrically connected to the receiver of the signal translation module, and the transmitter of the signal translation module is electrically connected to the receiver of the internal signal output module.

[0067] The microcontroller unit 2 includes a signal input module, a logic processing module, an external processing module, and an internal processing module. The signal input module transmits the integrated signal from the conversion loop unit 6 and the input loop unit 1 to the logic processing module. The logic processing module divides the integrated signal into external signals and internal signals. External signals are signals input through external input devices, and internal signals are signals generated by the internal module through operation. External signals are transmitted to the external processing module, and internal signals are transmitted to the internal processing module.

[0068] The microcontroller unit 2 also includes a control signal output module. The external processing module interprets and translates the external signals into corresponding external control signals and transmits them to the control signal output module. The internal processing module uses a magnetic field rotation algorithm to automatically calculate whether the stator's magnetic field is rotating forward, backward, or abnormal based on the internal signals, and transmits the calculated control signals to the control information output module. The control signal output module transmits the received signals to the switching loop unit 5. In this way, the microcontroller unit 2 realizes the calculation and start-up of the AC motor stator magnetic field rotation device and the transmission of control signals.

[0069] The transmitter of the information input module is electrically connected to the logic processing module. The transmitter of the logic processing module is also electrically connected to the receivers of both the internal and external processing modules. The transmitters of both the internal and external processing modules are also electrically connected to the receivers of the control signal output module.

[0070] The acquisition loop unit 7 includes current acquisition modules for each channel, a loop anomaly judgment module, a warning judgment module, a loop protection module, and a signal transmission module. Each current acquisition module is used to acquire the current signal of each channel and transmit the current signal to the loop anomaly judgment module. The loop anomaly judgment module uses the current signal to determine whether there is an anomaly. The judgment condition is whether the current is lost or unbalanced. If there is no anomaly, the current signal is transmitted to the signal transmission module. If there is an anomaly, the current signal is transmitted to the loop protection module. The signal transmission module converts the current signal into an acquisition signal and transmits it to the warning judgment module. The loop protection module locates the abnormal loop position based on the current signal and performs lockout protection on the abnormal loop, and sends an anomaly signal to the warning sending module.

[0071] The acquisition loop unit 7 also includes a warning issuing module, an abnormality handling module, and an acquisition signal output module. The warning issuing module receives the abnormal signal issued by the loop protection module and issues an alarm signal to the warning judgment module. The warning judgment module judges the received signal based on whether an alarm signal has been received. If an alarm signal is received, it transmits the alarm signal to the abnormality handling module. If no alarm signal is received, it transmits the received acquisition signal to the acquisition signal output module. The abnormality handling module processes the abnormal circuit according to the alarm signal. The acquisition signal output module outputs the acquisition signal to the conversion loop unit 6. In this way, the acquisition loop unit 7 realizes the reception of voltage signals and the protection of the loop.

[0072] The magnetic field sensing unit 8 includes a vertical magnetic field sensor 12 and a horizontal magnetic field sensor 13. The vertical magnetic field sensor 12 measures the magnetic field signal in the horizontal direction and converts the magnetic field signal into a voltage signal. The horizontal magnetic field sensor 13 measures the magnetic field signal in the horizontal direction and converts the magnetic field signal into a voltage signal.

[0073] The transmitting end of each current acquisition module is electrically connected to the receiving end of the warning judgment module. The transmitting end of the warning judgment module is also electrically connected to the receiving ends of the circuit protection module and the signal acquisition transmission module. The transmitting end of the circuit protection module is electrically connected to the receiving end of the warning issuing module. The transmitting ends of the warning issuing module and the signal acquisition transmission module are also electrically connected to the receiving end of the circuit anomaly judgment module. The transmitting end of the circuit anomaly judgment module is also electrically connected to the receiving ends of the anomaly handling module and the signal acquisition output module.

[0074] Example 2:

[0075] Please see Figure 5-12 This embodiment provides a technical solution based on Embodiment 1: when three-phase power frequency AC current passes through the measured sub-unit 9, the current change in the stator winding 16 of the measured sub-unit 9 is as follows: Figure 5As shown, to collect representative magnetic field data, time points t1, t2, and t3 were selected for magnetic field acquisition. Since the current changes rapidly at the power frequency AC point, a constant current source unit 4 and a switching circuit unit 5 were used to replace the power frequency AC current to ensure stable acquisition at time points t1, t2, and t3. A constant DC current was injected into the stator winding 16 of the measured sub-unit 9 through the switching circuit unit 5. This ensures that the magnitude and direction of the current in the stator winding remain unchanged during the energizing time, thus allowing the magnetic field to stably simulate the current state of the stator winding 16 in the measured sub-unit 9 at time points t1, t2, and t3. A bipolar and star-connected stator is used as an example. The specific circuit principle is as follows: Figure 6 Now, let's analyze the stator magnetic field at different time points. At time t1, phase u is connected to the positive terminal of constant current source unit 4, and phases v and w are connected to the negative terminal of constant current source unit 4. From this, we can obtain that iu is positive, and iv and iw are equal and negative, thus obtaining the current direction. Based on the current direction and the right-hand rule, we can plot the current magnetic field direction of the stator unit 9 being measured, as shown below. Figure 7 As shown in the figure, 12 stator windings 16 are evenly distributed on the measuring subunit 9. The current direction of every 3 windings is the same. Therefore, there are four magnetic fields 11 in the measuring subunit 9 at this moment. The directions of the magnetic fields 11 are as follows: Figure 7 Similarly, at time t2, phase V is connected to the positive terminal of constant current source unit 4, and phases u and w are connected to the negative terminal of constant current source unit 4. Thus, iv is positive, and iu and iw are equal and negative, obtaining the current direction. Based on the current direction and the right-hand rule, the current magnetic field direction of the measured sub-unit 9 can be plotted. Similarly, at time t3, phase W is connected to the positive terminal of constant current source unit 4, and phases u and v are connected to the negative terminal of constant current source unit 4. Thus, iw is positive, and iu and iv are equal and negative, obtaining the current direction. Based on the current direction and the right-hand rule, the current magnetic field direction of the measured sub-unit 9 can be plotted.

[0076] Therefore, it can be concluded that under constant DC current excitation, the strength and direction of the magnetic field at any point inside the measured sub-unit 9 will remain constant. When the measured sub-unit 9 winding exhibits regular changes in constant DC current, the strength and direction of the magnetic field at any point inside the motor stator will also exhibit regular changes. Thus, in determining the rotation direction of the measured sub-unit 9, an arbitrary magnetic field measurement point can be selected, and the magnetic field strength value can be measured using two magnetic field sensing units 8 with a 90° angle between their detection surfaces. Based on the obtained magnetic field strength value, the direction of the magnetic field at the current point can be calculated using trigonometric functions and vectors. Figure 8 As shown, the magnetic field sensing unit 8 mainly consists of a vertical magnetic field sensor 12 and a horizontal magnetic field sensor 13.

[0077] Taking the horizontal magnetic field sensor 13 as an example, when the horizontal magnetic field sensor 13 is in a magnetic field, such as Figure 9The horizontal magnetic field sensor 13 can convert the magnetic field signal into a voltage signal. The relationship between the output voltage signal of the horizontal magnetic field sensor 13 and the magnetic field is as follows: Figure 10 As shown, Figure 10 The horizontal axis represents the current magnetic field direction and intensity, and the vertical axis represents the output voltage value of the horizontal magnetic field sensor 13 expressing the magnetic field intensity and direction. When there is no magnetic field around the horizontal magnetic field sensor 13, the output voltage of the horizontal magnetic field sensor 13 is half of the supply voltage VCC. When the magnetic field lines are transmitted from the back of the horizontal magnetic field sensor 13, the output voltage of the horizontal magnetic field sensor 13 is greater than a certain value of the supply voltage VCC. The magnitude of the value is positively correlated with the magnetic field intensity and the perpendicularity of the magnetic field lines to the detection surface of the horizontal magnetic field sensor 13. When the magnetic field lines are transmitted from the front of the horizontal magnetic field sensor 13, the output voltage of the horizontal magnetic field sensor 13 is less than a certain value of the supply voltage VCC. The magnitude of the value is negatively correlated with the magnetic field intensity and the perpendicularity of the magnetic field lines to the detection surface of the magnetic field sensing unit 8.

[0078] The magnitude of the detected value of the horizontal magnetic field sensor 13 is related to the magnetic field strength and the perpendicularity of the magnetic field lines to the detection surface of the horizontal magnetic field sensor 13. To obtain the direction data of the magnetic field lines, this invention employs two magnetic field sensors placed at a 90° angle to each other at the measurement point, forming a magnetic field sensing unit 8. Simultaneously, the magnetic field data at this point is collected, yielding magnetic field strength A and magnetic field strength B. Then, magnetic field strength A and magnetic field strength B are represented by vectors, and their combined vector AB14 is obtained. This combined vector AB14 contains both magnetic field strength and direction data. When three-phase alternating current is applied to the measured subunit 9, an alternating magnetic field is generated internally, and the magnetic field strength changes in a sinusoidal pattern. Since the two magnetic field sensors are placed at a 90° angle in space, the waveforms of the magnetic field strength detected by each sensor also exhibit a 90° phase angle, such as... Figure 11 , Figure 11 The horizontal axis represents time t, and the vertical axis represents the processed output voltage value VL of the magnetic field sensor. The output voltage value VL expresses the magnetic field strength. Figure 11 Taking five time points t1, t2, t3, t4, and t5, the intensity values ​​of the two magnetic field sensors at these points are expressed as vectors. Here, it is agreed that magnetic field intensity A is expressed on the vertical axis and magnetic field intensity B is expressed on the horizontal axis. Thus, a plot is drawn. Figure 11 In the vectors AB_t1, AB_t2, AB_t3, AB_t4, and AB_t5, each vector represents the direction and intensity of the magnetic field at the current moment and point. Figure 12 By placing the first segments of the five sets of vectors together, the change pattern of the magnetic field direction at different times can be reflected, and the rotation direction of the magnetic field can be obtained as clockwise.

[0079] In actual use, the magnetic field sensing unit 8 is installed in a cylinder and placed at any position inside the measured subunit 9. Obviously, the obtained magnetic field strength value is not as ideal as all the values ​​derived in the theoretical derivation above. Therefore, it is necessary to obtain the angle of the magnetic field under different excitation currents by using the magnetic field rotation algorithm.

[0080] The specific algorithm for magnetic field rotation is as follows: Let the static value V of the two magnetic field sensing units 8 be... be The magnetic field strength values ​​measured after placing the energized stator were V. AC V BC First, V AC V BC Subtract the static value V respectively be This yields the magnetic field value V, which reflects the direction of the magnetic field. A V B Subsequently, according to V A V B The sign relationship between the positive and negative values ​​determines the quadrant of the coordinate system in which the vector lies, and then the magnetic field direction angle ∠T1 is calculated according to the following formula:

[0081] When V A >0&&V B When ∠T1 > 0 and ∠T1 is in the first quadrant: ∠T1 = arctan(V A / V B )*180 / π;

[0082] When V A >0&&V B When <0, ∠T1 is in the second quadrant: ∠T1=arctan(abs(V B ) / abs(V A ))*180 / PI+90;

[0083] When V A <0&&V B When <0, ∠T1 is in the third quadrant: ∠T1=arctan(abs(V A ) / abs(V B ))*180 / PI+180;

[0084] When V A <0&&V B >0, when ∠T1 is in the fourth quadrant: ∠T1=arctan(abs(V B ) / abs(V A ))*180 / PI+270;

[0085] When V A =0&&V B When ∠T1 > 0, and ∠T1 is in the first quadrant: ∠T1 = 0;

[0086] When V A >0&&V B =0, ∠T1 in the second quadrant: ∠T1 = 90;

[0087] When V A =0&&V B When ∠T1 < 0 and ∠T1 is in the third quadrant: ∠T1 = 180°;

[0088] When V A <0&&V B =0, when ∠T1 is in the fourth quadrant: ∠T1 = 270;

[0089] Similarly, when the direction of the excitation current of the measured subunit 9 changes according to the predetermined current, the magnetic field strength and direction at the magnetic field measurement point also change. Therefore, according to the above formula, the current magnetic field angle ∠T2 can be calculated. The rotation direction of the magnetic field can be obtained from the angle between ∠T1 and ∠T2. The calculation method for the rotation direction of the magnetic field is as follows:

[0090] ∠T = ∠T1 - ∠T2;

[0091] If ∠T>0, then when ∠T<180°, the magnetic field rotates in the forward direction, and when ∠T>180°, the magnetic field rotates in the reverse direction. If ∠T<0, then when ∠T>180°, the magnetic field rotates in the reverse direction, and when ∠T>180°, the magnetic field rotates in the forward direction.

[0092] Thus, by measuring the current change of subunit 9 twice, the two magnetic field direction change angles can be obtained. Then, the magnetic field rotation direction change can be obtained based on the angles. In the actual device, the current of subunit 9 will change three times to collect three magnetic field direction data. Through data redundancy, a more accurate measurement conclusion can be obtained.

[0093] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0094] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A system for detecting the rotation direction of the stator magnetic field of an AC motor, characterized in that, It includes an input circuit unit (1), a microcontroller unit (2), a power supply unit (3), a constant current source unit (4), a switching circuit unit (5), a measured subunit (9), a magnetic field sensing unit (8), a data acquisition circuit unit (7), a conversion circuit unit (6), and an output circuit unit (10); Input loop unit (1), the input loop unit (1) is used to transmit externally input signals to microcontroller unit (2); The microcontroller unit (2) receives the signal from the input circuit unit (1) and uses it to control the operation and start of the AC motor stator magnetic field rotation device, and transmits the control signal to the switching circuit unit (5). The switching circuit unit (5) receives the signal sent by the microcontroller unit (2) and sends the DC power of the constant current source unit (4) to the measured sub-unit (9) to generate a magnetic field in the measured sub-unit (9), and sends the acquisition signal in the magnetic field sensing unit (8) to the acquisition circuit unit (7). The measured sub-unit (9) receives the DC power emitted by the switching circuit unit (5), and the received DC power is used to excite the measured sub-unit (9) to generate a constant electromagnetic field. The magnetic field sensing unit (8) receives the data signal sent by the switching circuit unit (5) and uses it to acquire the magnetic field signal inside the product under test, convert the magnetic field signal into a voltage signal, and transmit the voltage signal to the acquisition circuit unit (7). The acquisition loop unit (7) receives the voltage signal emitted by the magnetic field sensing unit (8) and transmits the voltage signal into the conversion loop unit (6); The conversion circuit unit (6) receives the voltage signal emitted by the acquisition circuit unit (7), converts the voltage signal into a digital signal, and transmits the digital signal to the microcontroller unit (2). The output circuit unit (10) receives the control signal sent by the microcontroller unit (2) and converts the control signal output by the microcontroller unit (2) into the test result of the AC motor stator magnetic field rotation device. The constant current source unit (4) injects a regularly changing current into the measured subunit (9), and at the same time, it acquires magnetic field data at multiple time points through the magnetic field sensing unit (8) and the acquisition circuit unit (7). Through the magnetic field rotation algorithm of the microcontroller unit (2), it automatically calculates whether the magnetic field of the stator is rotating forward, reverse, or abnormal. The magnetic field sensing unit (8) includes a vertical magnetic field sensor (12) and a horizontal magnetic field sensor (13). The vertical magnetic field sensor (12) measures the magnetic field signal in the horizontal direction and converts the magnetic field signal into a voltage signal. The horizontal magnetic field sensor (13) measures the magnetic field signal in the horizontal direction and converts the magnetic field signal into a voltage signal.

2. The system for detecting the rotation direction of the stator magnetic field of an AC motor according to claim 1, characterized in that: The transmitting end of the input circuit unit (1) is electrically connected to the receiving end of the microcontroller unit (2). The transmitting end of the microcontroller unit (2) is electrically connected to the receiving end of the switching circuit unit (5). The transmitting end of the switching circuit unit (5) is electrically connected to the receiving ends of the magnetic field sensing unit (8) and the measured subunit (9), respectively. The transmitting end of the magnetic field sensing unit (8) is electrically connected to the receiving end of the acquisition circuit unit (7). The transmitting end of the acquisition circuit unit (7) is electrically connected to the receiving end of the conversion circuit unit (6). The transmitting end of the conversion circuit unit (6) is electrically connected to the receiving end of the microcontroller unit (2). The transmitting end of the microcontroller unit (2) is electrically connected to the receiving end of the output circuit unit (10).

3. The system for detecting the rotation direction of the stator magnetic field of an AC motor according to claim 1, characterized in that: The transmitting end of the power supply unit (3) is electrically connected to the receiving end of the microcontroller unit (2) and the constant current source unit (4) respectively. The power supply unit (3) is used to supply power to the microcontroller unit (2) and to provide power input to the constant current source unit (4). The transmitting end of the constant current source unit (4) is connected to the receiving end of the switching circuit unit (5). The constant current source unit (4) is used to excite the measured subunit (9) to generate a constant electromagnetic field.

4. The system for detecting the rotation direction of the stator magnetic field of an AC motor according to claim 1, characterized in that: The input loop unit (1) includes an external input module, a signal translation module and an internal signal output module. The external input module is composed of a button or an external input device, which provides signal data to the signal translation module. The signal translation module translates the signal data into an internal signal and transmits the internal signal to the internal signal output module. The internal signal output module transmits the received internal signal to the microcontroller unit (2).

5. The system for detecting the rotation direction of the stator magnetic field of an AC motor according to claim 1, characterized in that: The microcontroller unit (2) includes a signal input module, a logic processing module, an external processing module, and an internal processing module. The signal input module transmits the integrated signal of the conversion loop unit (6) and the input loop unit (1) to the logic processing module. The logic processing module divides the integrated signal into external signals and internal signals. The external signals are signals input through external input devices, and the internal signals are signals generated by the internal modules through operation. The external signals are transmitted to the external processing module, and the internal signals are transmitted to the internal processing module.

6. The system for detecting the rotation direction of the stator magnetic field of an AC motor according to claim 5, characterized in that: The microcontroller unit (2) also includes a control signal output module. The external processing module interprets and translates the external signal into a corresponding external control signal and transmits it to the control signal output module. The internal processing module uses a magnetic field rotation algorithm to automatically calculate whether the magnetic field of the stator is rotating forward, backward, or abnormal through the internal signal, and transmits the calculated control signal to the control information output module. The control signal output module transmits the received signal to the switching loop unit (5).

7. The system for detecting the rotation direction of the stator magnetic field of an AC motor according to claim 1, characterized in that: The acquisition circuit unit (7) includes a current acquisition module for each circuit, a circuit abnormality judgment module, a warning judgment module, a circuit protection module, and a signal transmission module. The current acquisition module for each circuit is used to acquire the current signal of each circuit and transmit the current signal to the circuit abnormality judgment module. The circuit abnormality judgment module uses the current signal to determine whether there is an abnormality. The judgment condition is whether the current is lost or whether the current is unbalanced. If there is no abnormality, the current signal is transmitted to the signal transmission module. If there is an abnormality, the current signal is transmitted to the circuit protection module. The signal transmission module converts the current signal into an acquisition signal and transmits it to the warning judgment module. The circuit protection module locates the abnormal circuit position according to the current signal and performs lockout protection on the abnormal circuit, and sends an abnormal signal to the warning sending module.

8. The system for detecting the rotation direction of the stator magnetic field of an AC motor according to claim 7, characterized in that: The acquisition circuit unit (7) further includes a warning issuing module, an abnormality handling module, and an acquisition signal output module. The warning issuing module receives the abnormal signal issued by the circuit protection module and issues an alarm signal to the warning judgment module. The warning judgment module judges the received signal based on whether an alarm signal is received. If an alarm signal is received, the alarm signal is transmitted to the abnormality handling module. If no alarm signal is received, the received acquisition signal is transmitted to the acquisition signal output module. The abnormality handling module processes the abnormal circuit according to the alarm signal. The acquisition signal output module outputs the acquisition signal to the conversion circuit unit (6).

Images