A control method

Abstract

A control method for controlling a motor includes: driving the motor to run according to a drive signal; receiving a first Hall signal output by a Hall sensor and determining whether the first Hall signal is abnormal; when the first Hall signal is abnormal, increasing the drive current of the coil to a value greater than a set value, and receiving a second Hall signal output by the Hall sensor again after the drive current of the coil is increased to a value greater than the set value, and determining whether the second Hall signal is abnormal; if so, determining that the Hall sensor has malfunctioned and reporting the corresponding information; if not, determining that the motor is stalled and reporting the corresponding information. This technical solution can distinguish between Hall sensor malfunction and motor stall, and the control method is simple.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and more specifically to a motor control method for identifying Hall sensor malfunctions and motor stall. Background Technology

[0002] An electric motor consists of a rotor and a stator. During motor operation, a Hall effect sensor is typically used to detect whether the rotor is rotating continuously, thereby determining whether the motor is stalled. When the Hall signal output by the sensor is abnormal, it may indicate that the motor is stalled or that the Hall sensor is malfunctioning. If the motor stalling and Hall sensor malfunction are not differentiated, and the motor continues to be controlled in reverse according to the stalling strategy when the Hall sensor is faulty, it may damage the motor. Therefore, distinguishing between motor stalling and Hall sensor malfunction is a technical problem. Summary of the Invention

[0003] The purpose of this invention is to provide a control method for controlling a motor, which can distinguish between motor stall and Hall sensor failure.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A control method for controlling a motor, characterized in that the control method includes:

[0006] The motor is driven to run according to the drive signal;

[0007] Receive the first Hall signal output by the Hall sensor and determine whether the first Hall signal is abnormal;

[0008] When the first Hall signal is abnormal, the drive current of the stator coil is increased to a value greater than the set value, and the second Hall signal output by the Hall sensor after the drive current of the stator coil is increased to a value greater than the set value is received again, and it is determined whether the second Hall signal is abnormal.

[0009] If yes, it is determined that the Hall sensor has malfunctioned, and the corresponding information is reported; if no, it is determined that the motor has stalled, and the corresponding information is reported.

[0010] When the first Hall signal is abnormal, this technical solution increases the drive current of the stator coil to a value greater than the set value, and then receives and judges whether the second Hall signal is abnormal again. Based on the result of the second Hall signal, it can distinguish between Hall sensor failure and motor stall. When the Hall sensor fails, it can avoid continuous reverse control according to the motor stall strategy, reduce damage to the motor, and the control method is simple. Attached Figure Description

[0011] Figure 1This is a structural diagram of one implementation of an electric valve;

[0012] Figure 2 This is a flowchart illustrating the first implementation method of the electric valve control method;

[0013] Figure 3 This is a schematic diagram of the stator coil current Ia and the Hall sensor output signal when the motor is running normally;

[0014] Figure 4 This is a schematic diagram of the stator coil current Ia and the Hall sensor output signal when the motor malfunctions;

[0015] Figure 5 This is a possible schematic diagram of the stator coil current Ib after the stator coil current increases and the Hall sensor output signal;

[0016] Figure 6 This is a possible schematic diagram of the changing trend of the Hall sensor output signal;

[0017] Figure 7 This is another possible schematic diagram of the stator coil current Ib after the stator coil current increases and the Hall sensor output signal;

[0018] Figure 8 This is another possible schematic diagram illustrating the changing trend of the Hall sensor output signal;

[0019] Figure 9 This is a flowchart illustrating the second embodiment of the control method for an electric valve;

[0020] Figure 10 This is a schematic diagram of another implementation of an electric valve;

[0021] Figure 11 This is a flowchart illustrating the third implementation method of the electric valve control method. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0023] Figure 1This is a schematic diagram of one embodiment of an electric valve, which can be applied to automotive air conditioning systems for flow adjustment and / or flow on / off control. The electric valve 100 includes a motor, a valve core, a valve body 1, and a circuit board 2. The valve body 1 has a valve port. The motor can be a stepper motor, including a rotor assembly and a stator assembly. The stator assembly includes a stator coil 3, and the rotor assembly includes a rotor 4 with permanent magnet material. The stator coil 3 and the circuit board 2 can be electrically / signally connected. In this embodiment, the stator coil 3 and the circuit board 2 are electrically connected via a coil power supply line 5 or pins. The circuit board 2 can integrate a control system, or the control system can be located on a host computer. The control system can send a drive signal to the motor to energize the stator coil 3. After the stator coil 3 is energized, it generates an excitation magnetic field. Under the action of the excitation magnetic field, the rotor 4 rotates and drives the valve core of the electric valve to move relative to the valve port, so that the valve port reaches the corresponding opening degree, thereby regulating the flow of the electric valve. In this embodiment, the motor is specifically used as an electric valve, but it can also be applied to other products, such as electric pumps.

[0024] In addition, the electric valve also includes a Hall sensor 6, which is located on the outer or inner circumference of the rotor 4. The Hall sensor 6 can be fixedly connected to the stator assembly (not shown in the figure) and can also be fixedly connected to the circuit board 2. The Hall sensor is electrically or signal-connected to the circuit board. The Hall sensor can detect the change in the magnetic field of the rotor passing through the location of the Hall sensor and output a Hall signal to the control system. The control system can detect the rotor's running position based on the Hall signal. The Hall sensor can be a switch-type Hall sensor, a linear Hall sensor, an angle Hall sensor, etc.; choosing a switch-type Hall sensor can reduce the manufacturing cost of the product. The switch-type Hall sensor has only two states: on and off. In the on state, it outputs a high-level signal, and in the off state, it outputs a low-level signal. In this embodiment, when the rotor rotates and the rotor's magnetic pole N switches to magnetic pole S or magnetic pole S switches to magnetic pole N, the Hall signal jumps (hereinafter referred to as the Hall signal). If there is no Hall signal jump, it is considered that the Hall sensor may be faulty or the motor may be stalled. In this embodiment, the number of switch-type Hall sensors is one. The Hall signal mentioned in the text refers to the high and low level output signal, which is an electrical signal. The Hall sensor is electrically connected or signal connected to the circuit board. Therefore, the Hall signal can be transmitted to the circuit board and can also be transmitted to external software through the interface of the electric valve.

[0025] Under normal operating conditions of the electric valve, the control system can send a drive signal to the motor to energize the stator coil 3. After the stator coil 3 is energized, it drives the rotor 4 to rotate. The stator coil current Ia is as follows: Figure 3As shown, the Hall effect curve exhibits periodic peaks and troughs during motor operation. When the rotor's magnetic pole switches from N to S or vice versa, the Hall sensor sequentially outputs high and low level signals. Based on the Hall sensor output signals, the rotor's specific rotation status can be determined using external software. When the Hall sensor output signal is abnormal, because the switch-type Hall sensor only outputs high and low level signals, the Hall signal curve when the Hall signal is abnormal is as shown in the diagram. Figure 4 The line shown does not change direction. There are two possible causes for the fault: one is that the motor is stalled and the rotor is stuck, and the other is that the Hall sensor is faulty.

[0026] See Figure 2 , Figure 2 for Figure 1 The flowchart illustrates the control method of the first embodiment of the electric valve. This control method can distinguish whether the abnormal Hall sensor signal is caused by a motor stall or a Hall sensor malfunction. The control method includes the following steps:

[0027] S11: Drives the motor to run according to the normal drive current based on the drive signal. The drive signal can be a LIN signal or other drive signals.

[0028] S12: Receive the first Hall signal output from the Hall sensor and determine if the first Hall signal is abnormal. If not, the motor runs normally; if yes, proceed to step S13. To increase reliability, a Hall signal abnormality means that the Hall signal does not change and remains unchanged for a period of time. For example, at least two cycles of motor operation (eight full steps) must generate four Hall signals without changing before it is considered abnormal. Otherwise, a short abnormal time may affect the judgment result. Here, one cycle refers to the rotor's magnetic pole N to magnetic pole S and back to magnetic pole N, or the rotor's magnetic pole S to magnetic pole N and back to magnetic pole S. In one cycle, the motor operates four full steps and outputs two Hall signals.

[0029] S13: Send a drive signal to increase the drive current acting on the stator coil to a level greater than a preset first current threshold and maintain this for a set duration. Similarly, the set duration can be two cycles or more; a duration that is too short may affect the judgment result.

[0030] S14: Receive the second Hall signal sent by the Hall sensor within the set time period again and determine if the second Hall signal is abnormal. If it is, determine that the Hall sensor is faulty and report the corresponding information; if not, determine that the motor is stalled and report the corresponding information. Similarly, an abnormal Hall signal here must persist for a certain period, such as at least two cycles of motor operation (eight full steps) without any change in the four Hall signals generated, before it is determined to be an abnormal Hall signal.

[0031] Under normal operating conditions of the motor and Hall sensor, the magnetic field strength generated by the rotor is greater than the magnetic field strength of the leakage flux generated by the stator coil (leakage flux refers to the magnetic field energy leaked into the air (space) through a specific magnetic circuit). Ideally, the Hall sensor should be sensitive enough to detect changes in the magnetic field generated by the rotor across the entire temperature detection range, but it should not be so sensitive as to simultaneously detect the leakage flux generated by the stator coil, otherwise it would affect the accuracy of rotor position determination. However, when the Hall signal is abnormal, increasing the drive current applied to the stator coil can enhance the magnetic field generated by the stator coil, thereby increasing the leakage flux of the stator coil. This causes the stator coil drive current Ib to increase to a level greater than or equal to a preset first current threshold. At this point, the leakage flux of the magnetic field generated by the stator coil is large enough for the Hall sensor to detect and output a signal. If the Hall sensor detects the leakage flux of the magnetic field generated by the stator coil, the Hall sensor outputs as shown in the image. Figure 5 The periodic alternation of high and low levels shown in the signal can be identified as a motor stall, where the rotor is stuck, rather than a malfunction of the Hall sensor. Figure 6 As shown in the figure, this corresponds to the changing trend of the Hall sensor output signal during the above process. At the beginning, the Hall signal is normal, with high and low levels alternating. Subsequently, the Hall signal becomes abnormal. Then, at point a, the stator coil drive current is increased, generating a certain leakage flux at the Hall sensor, which is detected. The Hall signal jumps, outputting high and low level signals. The waveform of the Hall signal output after increasing the stator coil drive current can be the same as the normal waveform because the frequency of the current applied to the stator coil remains unchanged, so the Hall signal frequency also remains unchanged. Although the increase in the stator coil drive current leads to an increase in the magnetic field strength at the Hall sensor, the switch-type Hall sensor only outputs high and low level signals, so the waveform of the Hall signal output is the same as the normal waveform.

[0032] If the Hall sensor still cannot detect the leakage flux generated by the stator coil, the Hall signal will remain abnormal, such as... Figure 7 As shown, it can be determined that the problem lies with the Hall sensor, not with the motor stalling. Figure 8 As shown in the figure, this figure corresponds to the change trend of the Hall signal in the above process. At the beginning, the Hall signal is normal, with high and low levels alternating. Then, the Hall signal becomes abnormal and does not jump. Then, at point a, the stator coil drive current is increased and continues for a set time. Within the set time, the Hall signal still does not change.

[0033] Finally, the corresponding information (Hall sensor failure or motor stall) is reported to the host computer / main controller connected to the control system through the control system.

[0034] The preset first current threshold is related to the magnetic field strength of the stator coil leakage flux, the parameters of the Hall sensor, and the installation position of the Hall sensor. When the stator coil drive current is greater than or equal to the preset first current threshold, the magnetic field of the leakage flux generated by the stator coil is sufficient for the Hall sensor to detect and output high and low level signals. That is, the magnetic field strength of the stator coil leakage flux at the Hall sensor is greater than the magnetic field strength at the operating point where the Hall sensor switches between high and low levels. In addition, the installation position between the Hall sensor and the stator coil also affects the magnetic field strength at the Hall sensor. The greater the distance between the Hall sensor and the stator coil, the larger the preset first current threshold. Therefore, the preset first current threshold needs to be determined according to the actual situation of the electric valve, and different electric valves may have different first current thresholds. The first current threshold needs to take into account the current that the chip and motor can withstand, and should not be too large. It is recommended to be less than the maximum current limit of the design scheme. Usually, the first current threshold is 1.5-2 times the normal drive current of the stator coil.

[0035] The aforementioned control method effectively identifies the specific cause of abnormal Hall signals, determining whether it's a Hall sensor malfunction or motor stall. This allows for better countermeasures based on the assessment, preventing continuous reverse control following a motor stall strategy when the Hall sensor fails, thus reducing motor damage. Furthermore, it eliminates the need for additional detection components, resulting in low control costs. Increasing the stator coil drive current increases the motor's driving force; when stall is not severe, this increased force may be sufficient to drive the rotor to rotate normally, promoting proper motor operation.

[0036] The above method illustrates a scenario with one Hall sensor, but it can also be extended to scenarios with two or more Hall sensors. The following describes the scenario with two Hall sensors, denoted as the first Hall sensor (Hall). 1、 The flowchart of the second Hall sensor Hall2 is as follows: Figure 9 As shown, the control method of the second embodiment of the corresponding electric valve includes the following steps:

[0037] S21: Drive the motor to run according to the normal drive current based on the drive signal.

[0038] S22: Receive the first Hall signal output by the first Hall sensor Hall1 and the second Hall signal output by the second Hall sensor Hall2 respectively, and determine whether the first Hall signal and the second Hall signal are both abnormal. If yes, proceed to step S24; otherwise, proceed to step S23.

[0039] S23: Determine whether the first Hall signal and the second Hall signal received in step S22 are both normal. If yes, then the motor runs normally. If not, determine that the first Hall sensor is faulty. 、If a fault occurs in the second Hall sensor, the corresponding fault information or alarm will be reported.

[0040] If not, it means that one Hall signal is abnormal and the other is normal, indicating that the motor is running normally and the problem lies with one of the Hall sensors. To determine which sensor is faulty, we can look at the corresponding Hall signal; the sensor with the abnormal Hall signal is the faulty sensor. A normal Hall signal means that the Hall signal changes alternating between high and low levels as the motor runs.

[0041] S24: Send a drive signal to increase the drive current applied to the stator coil to a level greater than a preset first current threshold and continue for a set duration. After step S24 is completed, proceed to step S25.

[0042] S25: Receive the third Hall signal output by the first Hall sensor and the fourth Hall signal output by the second Hall sensor within the set time period, respectively, and determine whether both the third Hall signal and the fourth Hall signal are abnormal. If so, determine whether the first Hall sensor... 、 If all second Hall sensors malfunction and report fault information or alarms, proceed to step S26.

[0043] S26: Determine whether the third Hall signal and the fourth Hall signal received in step S25 are both normal. If they are, determine that the motor is stalled and report the corresponding information or alarm. If not, determine that the motor is stalled and one of the first Hall sensor and the second Hall sensor is faulty, and report the corresponding information or alarm.

[0044] If not, it means that one Hall sensor signal is normal and the other is abnormal. If one Hall signal is normal, it indicates that the motor is stalled, but if the other Hall signal is abnormal, it indicates that the Hall sensor is faulty. To determine which sensor is faulty, you can look at the corresponding Hall signal; the sensor with the abnormal Hall signal is the faulty sensor.

[0045] Compared to a control method using a Hall sensor, this control method is relatively complex. Of course, a simpler control method, such as using a Hall sensor, can be implemented by detecting a Hall sensor... 1、 If at least one Hall2 sensor malfunctions, a drive current is increased to the stator coil. If at least one malfunction persists after increasing the drive current, it is considered a Hall sensor failure, and a fault is reported directly. During repair, both Hall sensors are replaced. It is understood that the number of Hall sensors can also be three or more, with a similar control method, which will not be listed here.

[0046] See Figure 10 , Figure 10 A schematic diagram of the structure of the electric valve according to another embodiment of the present invention is provided. Figure 1 Compared to the electric valve shown, this embodiment adds a detection coil 7, which is also electrically / signally connected to the circuit board 2. A small-sized detection coil 7 is chosen to save installation space. The detection coil is located around the Hall sensor 6, and both the detection coil and the Hall sensor can be fixedly connected to the stator assembly. When the electric valve is operating normally, the control system of the circuit board does not send a drive signal to the detection coil, and the detection coil does not operate. When the Hall sensor output signal is abnormal, the control system sends a drive signal to shut down the stator coil drive circuit, de-energizing the stator coil but energizing the detection coil. The cause of the fault is determined by the output result of the detection coil. A detailed flowchart is shown below. Figure 11 As shown, the control method of the corresponding third embodiment includes the following steps:

[0047] S31: Drive the motor to run according to the normal drive current based on the drive signal.

[0048] S32: Receive and determine whether the first Hall signal output by the Hall sensor is abnormal. If not, the motor runs normally. If yes, proceed to step S33.

[0049] S33: Send a drive signal to shut down the drive circuit of the stator coil, apply a drive current greater than the second current threshold to the detection coil and continue for a set duration.

[0050] S34: Receive and determine whether the second Hall signal output by the Hall sensor is abnormal within the set time period. If it is, determine that the Hall sensor is faulty and report the corresponding fault information or alarm. If not, determine that the motor is stalled and report the corresponding information or alarm.

[0051] In addition to step S33 and Figure 2 Except for step 13, which is different, the remaining steps are the same as in the first embodiment. In step S33, the drive circuit of the stator coil is first turned off, so that the stator coil is not energized. Regardless of whether the rotor is stuck or in a normal state, the stator coil is not energized and the rotor does not rotate. When the rotor stops rotating, a drive current is applied to the detection coil to generate a magnetic field, so that the Hall sensor detects and outputs a signal. This replaces the scheme of increasing the drive current of the stator coil in the first embodiment, and can also distinguish between motor stall and Hall sensor failure.

[0052] Similarly, the driving current applied to the detection coil must be greater than or equal to a preset second current threshold. The second current threshold is similar to the first current threshold and is related to the properties of the detection coil itself, the parameters of the Hall sensor, and the installation position between the detection coil and the Hall sensor. When the driving current of the detection coil is greater than or equal to the preset second current threshold, the magnetic field strength generated by the detection coil is sufficient for the Hall sensor to detect and output a signal. The preset second current threshold needs to be determined according to the actual situation. It is understood that the control method of this embodiment is not limited to a single Hall sensor; it can be extended to and applied to two or more Hall sensors. When there are two Hall sensors, the method can be... Figure 9 Similar to the process, step S24 is replaced by sending a drive signal to turn off the drive circuit of the stator coil, applying a drive current greater than the second current threshold to the detection coil and continuing for a set duration.

[0053] It should be noted that the above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still make modifications or equivalent substitutions to the present invention. All technical solutions and improvements that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A control method for controlling a motor, characterized in that, The control method includes: The motor is driven to run according to the drive signal; Receive the first Hall signal output by the Hall sensor and determine whether the first Hall signal is abnormal; When the first Hall signal is abnormal, the drive current of the stator coil is increased to a value greater than the set value, and the second Hall signal output by the Hall sensor after the drive current of the stator coil is increased to a value greater than the set value is received again, and it is determined whether the second Hall signal is abnormal. If yes, it is determined that the Hall sensor has malfunctioned, and the corresponding information is reported; if no, it is determined that the motor has stalled, and the corresponding information is reported.

2. The control method as described in claim 1, characterized in that, The control method includes: The motor is driven to run according to the drive signal; Receive the first Hall signal output by the Hall sensor and determine whether the first Hall signal is abnormal; When the first Hall signal is abnormal, a drive signal is sent to increase the drive current of the stator coil so that the drive current is greater than the first current threshold and continues for a set time. The system receives the second Hall signal output by the Hall sensor within the set time period again and determines whether the second Hall signal is abnormal. If it is, the system determines that the Hall sensor has malfunctioned and reports the corresponding information. If it is not, the system determines that the motor has stalled and reports the corresponding information.

3. The control method as described in claim 1, characterized in that, The control method includes: The motor is driven to run according to the drive signal; Receive the first Hall signal output by the Hall sensor and determine whether the first Hall signal is abnormal; When the first Hall signal is abnormal, a drive signal is sent to shut down the drive circuit of the stator coil, and a drive current greater than the second current threshold is applied to the detection coil for a set duration. The system receives the second Hall signal output by the Hall sensor within the set time period again and determines whether the second Hall signal is abnormal. If it is, the system determines that the Hall sensor has malfunctioned and reports the corresponding information. If it is not, the system determines that the motor has stalled and reports the corresponding information.

4. The control method as described in claim 2, characterized in that, The number of Hall sensors is 1-3. The Hall sensors are switch-type Hall sensors. If the Hall sensors are not faulty, the leakage magnetic field generated by the stator coil when the driving current of the stator coil is greater than the first current threshold can be detected by the Hall sensors.

5. The control method as described in claim 3, characterized in that, The number of Hall sensors is 1-3. The Hall sensors are switch-type Hall sensors. The detection coil is set closer to the Hall sensor than the stator coil. If the Hall sensor is not faulty, the magnetic field generated by the detection coil can be detected by the Hall sensor when the driving current of the detection coil is greater than the second current threshold.

6. The control method as described in claim 2 or 4, characterized in that, The control method includes: S11: Drive the motor according to the normal drive current based on the drive signal; S12: Receive the first Hall signal output by the Hall sensor and determine whether the first Hall signal is abnormal. If not, the motor runs normally. If yes, proceed to step S13. S13: Send a drive signal to increase the drive current acting on the stator coil to a level greater than a preset first current threshold and continue for a set duration; S14: Receive the second Hall signal output by the Hall sensor within the set time period again and determine whether the second Hall signal is abnormal. If it is, determine that the Hall sensor has failed and report the corresponding information; if not, determine that the motor has stalled and report the corresponding information.

7. The control method as described in claim 6, characterized in that: The first current threshold is 1.5-2 times the normal drive current.

8. The control method as described in claim 3 or 5, characterized in that, The control method includes: S31: Drive the motor to run according to the normal drive current based on the drive signal; S32: Receive the first Hall signal output by the Hall sensor and determine whether the first Hall signal is abnormal. If not, the motor runs normally. If yes, proceed to step S33. S33: Send a drive signal to turn off the drive circuit of the stator coil, apply a drive current greater than the second current threshold to the detection coil and continue for a set time; S34: Receive the second Hall signal output by the Hall sensor within the set time period again and determine whether the second Hall signal is abnormal. If it is, determine that the Hall sensor has failed and report the corresponding information; if not, determine that the motor has stalled and report the corresponding information.

9. The control method as described in claim 2 or 4, characterized in that, The Hall sensor includes a first Hall sensor and a second Hall sensor, and the control method includes: S21: Drive the motor to run according to the drive signal; S22: Receive the first Hall signal output by the first Hall sensor and the second Hall signal output by the second Hall sensor respectively, and determine whether the first Hall signal and the second Hall signal are both abnormal. If yes, proceed to step S24; otherwise, proceed to step S23. S23: Determine whether the first Hall signal and the second Hall signal are both normal. If they are, then the motor runs normally. If not, determine that one of the first Hall sensor and the second Hall sensor is faulty, and report the corresponding information. S24: Send a drive signal to increase the drive current acting on the stator coil to a level greater than a preset first current threshold and continue for a set duration; S25: Receive the third Hall signal output by the first Hall sensor and the fourth Hall signal output by the second Hall sensor within the set time period respectively, and determine whether the third Hall signal and the fourth Hall signal are both abnormal. If so, determine that the first Hall sensor and the second Hall sensor are both faulty, and report the corresponding information; if not, execute step S26. S26: Determine whether the third Hall signal and the fourth Hall signal are both normal. If they are, determine that the motor is stalled and report the corresponding information. If not, determine that the motor is stalled and one of the first Hall sensor and the second Hall sensor is faulty, and report the corresponding information.

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