WO2022217699A1

WO2022217699A1 - Resistance-encountering stop control method for single-phase asynchronous electric motor

Info

Publication number: WO2022217699A1
Application number: PCT/CN2021/095401
Authority: WO
Inventors: 孙勇; 王越洋; 包波军; 吴龙文
Original assignee: 宁波杜亚机电技术有限公司
Priority date: 2021-04-16
Filing date: 2021-05-24
Publication date: 2022-10-20
Also published as: CN113131797B; CN113131797A

Abstract

Disclosed in the present invention is a resistance-encountering stop control method for a single-phase asynchronous electric motor. The single-phase asynchronous electric motor comprises a controller and an electric motor, wherein the electric motor comprises two control ends, which are respectively used for controlling forward rotation and reverse rotation; the controller comprises an MCU, and a first relay and a second relay, which are controlled by the MCU; the first relay and the second relay are respectively connected to one of the control ends of the electric motor; and one I/O port of the MCU is connected to one control end of the electric motor and the connection position is a first detection point, and the other I/O port of the MCU is connected to the other control end of the electric motor and the connection position is a second detection point. The resistance-encountering stop control method comprises the following steps: 1) a signal detection module respectively detecting voltages at a first detection point and a second detection point, performing rectification and filtering to obtain square wave voltage signals, and then outputting same to an MCU; and 2) the MCU obtaining, according to the two square wave voltage signals, a value Δt of the time difference between adjacent rising edges of the two signals, and when a change in Δt exceeds a certain range, determining that resistance is encountered.

Description

A blocking control method for a single-phase asynchronous motor

technical field

The invention relates to a power device, in particular to a method for controlling a stop when a single-phase asynchronous motor encounters a block.

Background technique

In life, motor-driven rolling shutter doors and windows and sunshades have been widely used, which reduces the trouble of manual pushing and dragging, and facilitates people's lives.

However, rolling shutter doors, windows or sunshades usually need to set the function of stopping or rebounding in case of resistance, so as to avoid dragging the load after the load encounters resistance during operation. If the operation cannot be automatically stopped, it will cause unnecessary personal injury or financial damage. At the same time, the motor is also prone to stall damage, which affects the service life of the motor. Therefore, the motor needs to be equipped with a resistance detection device and a controller, so as to realize the function of stopping or rebounding when the motor is blocked.

At present, the common way to realize the motor stopping and stopping is to add additional resistance detection devices, such as mechanical triggering, infrared detection, rotational speed detection, etc., generally need to install additional detection devices, which have high cost, low sensitivity, and unreliable detection. Problems such as misoperation affect normal use.

In addition, there is also a kind of electronic circuit of AC motor resistance rebound of rolling shutter door disclosed in Chinese Patent Application No. 201710721695.6, the circuit includes mains input interface CN3, AC input interface CN2, fuse F1, varistor RV1, output control relay RLY2, output control relay RLY3, current transformer T1, transformer T2, rectifier bridge stack REC1, current zero-cross detection Q4 and voltage zero-cross detection Q5. The patent judges whether it encounters resistance by detecting the change of the current characteristic caused by the load change, and controls it.

However, this method of judging by the voltage and current phase difference cannot directly obtain the current of the detection point. It is necessary to install an additional current transformer to detect the small current, and then obtain it through proportional amplification. The detection error is large and it is easy to cause misoperation.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is aimed at the problems existing in the above-mentioned prior art, and provides a method for controlling a single-phase asynchronous motor when encountering a blockage, which has the advantages of low cost, high sensitivity and good reliability, and can accurately realize the operation process of the AC motor. The encounter of resistance or resistance to rebound.

The technical solution adopted by the present invention to solve the above-mentioned technical problems is: a method for controlling a single-phase asynchronous motor when encountering a blockage. The two control terminals of the motor are rotated, and the controller includes an MCU, a first relay and a second relay controlled by the MCU, and the first relay and the second relay are respectively connected to one of the control terminals of the motor. One I/O port of the MCU is connected to one control end of the motor and the connection is the first detection point, and another I/O port of the MCU is connected to the other control end of the motor and the connection is the second detection point, The method for controlling the stop in case of obstruction includes the following steps:

1) The signal detection module detects the voltages of the first detection point and the second detection point respectively and performs rectification and filtering to obtain a square wave voltage signal, which is then output to the MCU;

2) The MCU obtains the time difference value Δt of the adjacent rising edges of the two signals according to the two square wave voltage signals, and judges that it is blocked when the change of Δt exceeds a certain range.

Preferably, the way of judging the change of Δt is, in step 2), select adjacent a Δt as a group to obtain the average value M of a Δt, when the rate of change of M exceeds the threshold, it is judged as encountering resistance .

Preferably, the method for judging the rate of change of the average value M is that when one of the following two conditions is satisfied, it is determined that the rate of change of M exceeds the threshold:

1) Comparing the difference between two adjacent groups of M, it satisfies that the difference between the adjacent two groups of M is greater than the first preset value A1;

2) Comparing the difference between the two adjacent groups M, it is satisfied that at least two adjacent differences are greater than the preset value A2.

In order to make it easier for users to adjust the sensitivity of judging the blockage according to their needs, and to avoid misjudgment or no response when blockage caused by different installation environments and load conditions, A1 and A2 are preset with at least two values arranged in order from small to large. Group.

In order to avoid the malfunction of the control system caused by signal fluctuations and abnormal values, when selecting adjacent a Δt as a group, the MCU1 automatically filters the abnormal values, and when a certain Δt deviation is greater than 30% of M, it is judged as an abnormal value.

Preferably, the value range of a is ≥7.

Compared with the prior art, the present invention has the advantages that it only needs to connect the MCU and the motor to detect the voltages of the two control terminals, without setting other detection devices, the cost is low, and the voltage signals of the two detection points are based on the voltage signals of the two detection points. The rate of change of the phase difference is the basis for judgment, and the detection reliability is high; the preset value of the standard for judging blockage is preset with at least two groups of values arranged in order from small to large, which is convenient for users to adjust and judge the blockage according to their needs. Sensitivity to avoid misjudgment or no response when blocked due to different installation environments and load states; screen and remove abnormal signal values during the judgment process, and reduce the influence of abnormal signal values by calculating the average value of the array to avoid signal fluctuations and abnormality The value causes the control system to malfunction, making the control more accurate and reliable.

Description of drawings

Fig. 1 is the principle block diagram of the controller of the motor of the present invention;

Fig. 2 is the detection principle block diagram of the controller of the motor of the present invention;

FIG. 3 is a schematic diagram of a voltage waveform processed by the MCU of the controller of the present invention when the motor is running.

Detailed ways

The present invention will be further described in detail below with reference to the embodiments of the accompanying drawings.

The tubular motor used to drive the roller shutter or sunshade generally adopts a single-phase asynchronous AC motor (a type of induction motor), which can be directly connected to the household 220V mains, and the main and secondary windings are switched by setting a relay, thereby changing the rotation direction of the motor. , Due to the stable load size, the single-phase asynchronous AC motor runs at a constant speed and has a constant output during normal operation.

Referring to Figure 1 and Figure 2, a method for controlling a single-phase asynchronous motor when encountering a blockage includes a controller and a motor 3. In the prior art, the motor 3 is usually connected with three external wires, two of which are control terminals, and one of the control terminals is After the power is turned on, the motor 3 is controlled to rotate forward, and the other one is turned on to control the motor 3 to rotate reversely. The controller includes MCU1 and relay group 2. MCU1 controls the action of relay group 2, so that the two wires at the control end are connected or disconnected from the mains power supply, so as to control the forward or reverse rotation of motor 3. The relay group 2 can be a normally open double relay. In this embodiment, the relay group 2 includes two identical normally open relays, which are the first relay 21 and the second relay 22 respectively. The first relay 21 is connected to the motor. One control terminal of 3, the second relay 22 is connected to the other control terminal of motor 3, so as to control the forward or reverse rotation of motor 3, that is, when MCU1 controls the first relay 21 to close and conduct, it controls motor 3 to rotate forward, and when MCU1 controls After the second relay group 22 is closed and turned on, the motor 3 is controlled to reverse, and only one of the two relays can be turned on at the same time.

The two I/O ports of MCU1 are respectively connected to the two control terminals of motor 3 through the signal detection module. The connection of the control terminal of the control inversion), the signal detection module is used to detect the voltage signals of the two detection points respectively, rectify and filter them and output the corresponding square wave of the voltage signal to the MCU1, as shown in Figures 2 and 3, The voltage signal detected at the first detection point O1 corresponds to the square wave S1, and the voltage signal detected at the second detection point O2 corresponds to the square wave S2.

When the motor 3 starts to run, the MCU1 detects the voltage of the first detection point O1 and the second detection point O2. When the motor 3 runs at a constant speed with a constant load, the stator and rotor inside the motor 3 maintain electromagnetic balance during the operation. The phase difference between the voltages of the detection point O1 and the second detection point O2 remains stable, see Figure 3, the upper square wave S1 represents the first detection point O1, and the lower square wave S2 represents the second detection point O2; when encountering resistance, That is, when the roller blind falls to the ground or an obstacle, the load suddenly decreases, so that the output speed of the motor 3 (that is, the rotor speed) becomes smaller, resulting in changes in the electrical parameters of the main winding and the secondary winding of the stator part of the motor 3. At this time, the first detection The phase difference between the voltages at the point O1 and the second detection point O2 changes, and then the controller controls the motor 3 to stop or rebound.

Alternatively, the resistance can also be a sudden increase in the load, that is, the roller blind rises to be completely retracted, and the motor is locked at this time, which also causes the electrical parameters of the main winding and the secondary winding of the stator part of the motor to change.

Specifically, it includes the following steps:

1) The signal detection module detects the voltage of the first detection point O1 and the second detection point O2 respectively, and performs rectification and filtering to obtain a square wave voltage signal, which is then output to MCU1;

2) The MCU (1) obtains the time difference value Δt between the adjacent rising edges of the two signals according to the two square wave voltage signals, and judges that it is blocked when the change of Δt exceeds a certain range.

In the present embodiment, the way of judging that the change of Δt in step 2) exceeds a certain range is: select adjacent a Δt as a group, and obtain the average value M of a Δt, when the change rate of M exceeds the threshold, Then it is judged that the condition is met, that is, the motor 3 encounters resistance. Preferably, the value range of a is ≥7. When one of the following two conditions is met, it is judged that the rate of change of M exceeds the threshold:

1) Compare the difference between the adjacent two groups of M, and satisfy that the difference between the adjacent two groups of M is greater than the first preset value A1; that is, the average values of the adjacent two groups are M1 and M2, respectively, and satisfy M1>A1, M2>A1 ;

2) Compare the difference between two adjacent groups of M, and satisfy that at least two adjacent differences are greater than the preset value A2; if the average values of the three adjacent groups are taken as M1, M2 and M3 respectively, and M2-M1>A2 is satisfied At the same time M3-M2>A2.

A1 and A2 can be preset with at least two groups of values arranged in order from small to large. Selecting the values of different groups can facilitate the user to adjust the sensitivity of judging the stop in case of obstruction according to the needs, and avoid the occurrence of encounters caused by different installation environments and load states. Blocking misjudgment or no response when blocked.

In the above selection of adjacent a Δt as a group, the MCU1 automatically filters out abnormal values, and when a certain Δt deviation is greater than 30% of M, it is judged as an abnormal value.

After MCU1 judges that it encounters resistance, it controls the action of the moving contact of relay group 2, so that the motor 3 runs in the reverse direction or stops to solve the problem of encountering resistance.

When the motor stops, it will realize the function of automatically setting the stroke (stop when it encounters resistance at the stroke point each time it runs). It can also cooperate with the timer, data storage or other travel detection device (existing technology) inside the controller to realize the automatic recording of the limit point (ie the travel point) after the first operation of the roller blind or sunshade, and the user can manually Prevents roller blinds or shades from stopping in a certain position, allowing them to run at that stroke length later.

Claims

A method for controlling a single-phase asynchronous motor when encountering a blockage, the single-phase asynchronous motor comprises a controller and a motor (3), the motor (3) comprises two control terminals for controlling forward rotation and reverse rotation, respectively, The controller includes an MCU (1), a first relay (21) and a second relay (22) controlled by the MCU (1), and the first relay (21) and the second relay (22) are respectively connected to the motor ( One of the control terminals of 3) is characterized in that: an I/O port of the MCU (1) is connected to a control terminal of the motor (3) and the connection point is the first detection point (O1), and the MCU ( The other I/O port of 1) is connected to the other control end of the motor (3) and the connection is the second detection point (O2).

1) The signal detection module detects the voltages of the first detection point (O1) and the second detection point (O2) respectively, and performs rectification and filtering to obtain a square wave voltage signal, which is then output to the MCU (1);

2) The MCU (1) obtains the time difference value Δt between the adjacent rising edges of the two signals according to the two square wave voltage signals, and judges that it is blocked when the change of Δt exceeds a certain range.
The method for controlling a blockage stop of a single-phase asynchronous motor according to claim 1, wherein in step 2), select adjacent a Δt as a group, and obtain the average value M of a Δt, when the value of M is When the rate of change exceeds the threshold, it is judged to be blocked.
The method for controlling a blockage of a single-phase asynchronous motor according to claim 2, wherein: when one of the following two conditions is met, it is determined that the rate of change of M exceeds the threshold:

1) Comparing the difference between two adjacent groups of M, it satisfies that the difference between the adjacent two groups of M is greater than the first preset value A1;

2) Comparing the difference between the two adjacent groups M, it is satisfied that at least two adjacent differences are greater than the preset value A2.
The method for controlling a single-phase asynchronous motor to stop when blocked according to claim 3, wherein A1 and A2 are respectively preset with at least two groups of numerical values arranged in ascending order.
The method for controlling stop in case of blockage of a single-phase asynchronous motor according to claim 2, characterized in that: when selecting adjacent a Δt as a group, the MCU (1) automatically filters out abnormal values, and when a certain Δt deviation is greater than M 30% were judged as outliers.
The method for controlling stop in case of blockage of a single-phase asynchronous motor according to claim 2, wherein the value range of a is ≥7.