Motor stall protection device and motor stall protection method

Abstract

The present invention provides a motor stall protection device and a motor stall protection method. The motor stall protection device comprises a motor, a motor voltage detection unit, a power supply unit, a control unit and a drive unit, wherein the control unit comprises a PID voltage stabilization control module, a duty cycle output module, a comparison module and a control module. The PID voltage stabilization control module is connected with the motor voltage detection unit and the control module, and is used to perform PID regulation on the voltage at both ends of the motor after the motor is started, so that the motor runs at a constant target voltage; the duty cycle output module is connected with the control module and the comparison module, and is used to output a real-time duty cycle after the motor is started. The comparison module is used to compare the real-time duty cycle with a preset maximum limit duty cycle, and transmit the comparison result to the control module. When the real-time duty cycle is greater than the maximum limit duty cycle, the control module outputs a control signal to the drive unit to drive the motor to shut down, thereby achieving effective stall protection.

Description

Technical Field

[0001] The invention relates to a motor stall protection device and a motor stall protection method, belonging to the technical field of automatic control. Background Art

[0002] The stall protection method used by existing floor scrubbers usually uses a current sensor to detect the current of the roller brush motor. When the current is greater than a threshold, the floor scrubber is determined to be stalled, and then the roller brush motor is controlled to stop. However, after the current sensor is introduced into such a stall protection method, not only the cost is increased, but also the sampling accuracy of the current is required to be high, and a high-performance processor is required for processing, making the implementation method quite complicated.

[0003] In addition, the existing stall protection method only executes protection when the scrubber triggers a stall. Since the roller brush of the scrubber is driven by a pulley, frequent stalls will increase the tension of the belt and easily cause tooth snapping, causing the teeth on the pulley to be worn, which in turn causes the roller brush motor to be unable to use normally due to belt damage.

[0004] In view of this, it is indeed necessary to propose improvements to the existing motor stall protection method to solve the above problems. Summary of the invention

[0005] The object of the present invention is to provide a motor stall protection device to solve the problems of high stall protection cost and complex implementation of existing floor scrubbers.

[0006] To achieve the above-mentioned purpose, the present invention provides a motor stall protection device, comprising: a motor; a motor voltage detection unit connected to the motor and used to detect the voltage at both ends of the motor in real time; a power supply unit connected to the motor and used to provide electric energy to the motor; a control unit connected to the power supply unit and the motor voltage detection unit and used to receive the voltage value detected by the motor voltage detection unit and output a control signal according to the voltage value; and a driving unit connected to the power supply unit, the motor and the control unit and used to drive the motor to run or shut down according to the control signal output by the control unit; wherein the control unit includes a PID voltage stabilization control module , a duty cycle output module, a comparison module and a control module. The PID voltage stabilization control module is connected with the motor voltage detection unit and the control module, and is used to perform PID adjustment on the voltage across the motor after the motor is started, so that the motor runs at a constant target voltage; the duty cycle output module is connected with the control module and the comparison module, and is used to output a real-time duty cycle after the motor is started. The comparison module is used to compare the real-time duty cycle with a preset maximum limit duty cycle, and transmit the comparison result to the control module. When the real-time duty cycle is greater than the maximum limit duty cycle, the control module outputs a control signal to the drive unit to drive the motor to shut down.

[0007] As a further improvement of the present invention, the target voltage is defined as U and the real-time duty cycle is defined as D1, then D1=U / Um, wherein Um is the voltage across the motor detected in real time by the motor voltage detection unit.

[0008] As a further improvement of the present invention, the duty cycle output module is also used to output an initial duty cycle when the motor is initially started until the voltage across the motor is constant at a target voltage. The initial duty cycle is defined as De, then De=U / Ue, wherein U is the target voltage and Ue is the bus voltage of the power supply unit.

[0009] As a further improvement of the present invention, the motor stall protection device also includes a power supply voltage detection unit, which is respectively connected to the power supply unit and the control module, and is used to detect the voltage across the power supply unit in real time; the duty cycle output module is also used to output an initial duty cycle when the motor is initially started until the voltage across the motor is constant at a target voltage, and the initial duty cycle is defined as D0, then D0=U / U0, wherein U is the target voltage and U0 is the voltage across the power supply unit detected in real time by the power supply voltage detection unit.

[0010] As a further improvement of the present invention, the power supply unit is a battery pack, and U0 is the real-time output voltage of the battery pack.

[0011] As a further improvement of the present invention, the maximum limit duty cycle is a fixed value.

[0012] As a further improvement of the present invention, the maximum limit duty cycle=k*real-time duty cycle, wherein k is a critical coefficient, and its value range is 1.0 to 1.5.

[0013] The present invention also aims to provide a motor stall protection method, which is not only simple to implement and has low implementation cost, but also can achieve the maximum constant torque output of the motor without triggering overcurrent protection, thereby achieving effective stall protection.

[0014] To achieve the above object, the present invention provides a motor stall protection method, which is applied to the above motor stall protection device and mainly includes the following steps:

[0015] S1, start the motor until the voltage across the motor is constant at the target voltage;

[0016] S2, the motor voltage detection unit detects the voltage at both ends of the motor in real time, and the PID voltage control module performs PID regulation on the voltage at both ends of the motor to make the motor run at a constant target voltage;

[0017] S3, the duty cycle output module outputs the real-time duty cycle, and transmits the real-time duty cycle to the comparison module, the comparison module compares the real-time duty cycle with the preset maximum limit duty cycle, and transmits the comparison result to the control module;

[0018] S4. When the real-time duty cycle is greater than the maximum limit duty cycle, the control module outputs a control signal to the drive unit, and the drive unit drives the motor to shut down; when the real-time duty cycle is less than or equal to the maximum limit duty cycle, the control module outputs a control signal to the drive unit, and the drive unit drives the motor to continue running.

[0019] As a further improvement of the present invention, the step S1 is specifically: starting the motor with an initial duty cycle until the voltage across the motor is constant at a target voltage.

[0020] As a further improvement of the present invention, the initial duty cycle is defined as De, then De=U / Ue, wherein U is the target voltage and Ue is the bus voltage of the power supply unit connected to the motor.

[0021] As a further improvement of the present invention, the initial duty cycle is defined as D0, then D0=U / U0, wherein U is the target voltage and U0 is the output voltage of the power supply unit connected to the motor.

[0022] As a further improvement of the present invention, the step S4 further includes: when the real-time duty cycle is continuously greater than the maximum limit duty cycle within a set time period, the control module outputs a control signal to the drive unit, and the drive unit drives the motor to shut down.

[0023] As a further improvement of the present invention, the set time period is 200ms to 1s.

[0024] The beneficial effects of the present invention are as follows: the motor stall protection device and the motor stall protection method of the present invention compare the real-time duty cycle output by the duty cycle output module with the preset maximum limit duty cycle, and when the real-time duty cycle is greater than the maximum limit duty cycle, the control module promptly controls the motor to shut down. Not only is the implementation method simple and the implementation cost low, but it can also achieve the maximum constant torque output of the motor without triggering overcurrent protection, thereby achieving effective stall protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural block diagram of a motor stall protection device according to a preferred embodiment of the present invention.

[0026] Figure 2 yes Figure 1 A structural block diagram of a preferred embodiment of the control unit in FIG.

[0027] Figure 3 It is a flow chart of the motor stall protection method of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0029] It should be noted here that in order to avoid obscuring the present invention due to unnecessary details, only structures and / or processing steps closely related to the scheme of the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0030] In addition, it should be noted that the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or apparatus.

[0031] like Figure 1 and Figure 2 As shown, the present invention provides a motor stall protection device, including a motor 10, a motor voltage detection unit 20, a power supply unit 30, a control unit 40 and a drive unit 50. The power supply unit 30 is connected to the motor 10 to provide electric energy to the motor 10; the motor voltage detection unit 20 is connected to the motor 10 to detect the voltage at both ends of the motor 10 in real time; the control unit 40 is connected to the power supply unit 30 and the motor voltage detection unit 20 to receive the voltage value detected by the motor voltage detection unit 20 and output a control signal according to the voltage value; the drive unit 50 is connected to the power supply unit 30, the motor 10 and the control unit 40 to drive the motor 10 to run or shut down according to the control signal output by the control unit 40.

[0032] In a preferred embodiment of the present invention, the power supply unit 30 is a battery pack, and the motor 10 is a roller brush motor, and preferably a brushed motor. In this case, the motor stall protection device can be applied to a floor scrubber, and can protect the roller brush motor when the roller brush of the floor scrubber is stalled.

[0033] Specifically, the control unit 40 includes a PID voltage stabilization control module 41, a duty cycle output module 42, a comparison module 43 and a control module 44, wherein the PID voltage stabilization control module 41 is connected to the motor voltage detection unit 20 and the control module 44, and is used to perform PID regulation on the voltage across the motor 10 after the motor 10 is started, so that the motor 10 keeps running at a constant target voltage U. The duty cycle output module 42 is connected to the control module 44 and the comparison module 43, and is used to output a real-time duty cycle D1 after the motor 10 is started. The comparison module 43 is used to compare the real-time duty cycle D1 with a preset maximum limit duty cycle Dlim, and transmit the comparison result to the control module 44, and the control module 44 controls the motor 10 to continue running or shut down according to the specific comparison result.

[0034] The driving unit 50 includes an electronic switch (not shown), one end of which is connected to the power supply unit 30 and the other end is connected to the motor 10. At the same time, the electronic switch is also communicatively connected to the control module 44, so that the control signal emitted by the control module 44 can be used to control the closing of the electronic switch, so that the power supply unit 30 and the motor 10 are connected, and the power supply unit 30 supplies power to the motor 10 to ensure that the motor 10 can operate normally; the control signal emitted by the control module 44 can also be used to control the opening of the electronic switch, so that the power supply unit 30 and the motor 10 are disconnected, the power supply unit 30 stops supplying power to the motor 10, and the motor 10 is powered off.

[0035] After the motor 10 starts normally, the calculation formula of the real-time duty cycle D1 is: D1 = U / Um, where U is the target voltage and Um is the voltage across the motor 10 detected in real time by the motor voltage detection unit 20. The purpose of setting the real-time duty cycle D1 is that when the motor 10 is initially started, the output voltage of the motor 10 can reach the target voltage U. After the motor 10 runs for a period of time, the output voltage of the motor 10 will change due to the presence of the load. At this time, if you want to determine whether the roller brush is blocked due to external reasons, you must understand the load situation. In the case of omitting the current sensor to detect the current of the motor 10, the best choice is to judge by the change of the voltage value across the motor 10. In other words, a coefficient (preferably the duty cycle) can be set to determine whether the roller brush is blocked by the change of the coefficient.

[0036] Back to the present embodiment, when the real-time duty cycle D1 is greater than the maximum limit duty cycle Dlim, it is determined that the roller brush is blocked, and at this time, the control module 44 outputs a control signal to the drive unit 50 to drive the electronic switch to disconnect, so that the motor 10 is powered off; when the real-time duty cycle D1 is less than or equal to the maximum limit duty cycle Dlim, the control module 44 outputs a control signal to the drive unit 50 to drive the motor 10 to continue running. It can be seen that the present invention uses the real-time duty cycle D1 to compare with the maximum limit duty cycle Dlim, and can quickly determine the load condition of the motor 10, which has the advantages of simple implementation and low implementation cost.

[0037] Preferably, the maximum limit duty cycle Dlim is a fixed value. Of course, in other embodiments, the maximum limit duty cycle Dlim can also be calculated by the calculation formula Dlim=k*D1, where k is a critical coefficient with a value range of 1.0 to 1.5. Of course, the value of the critical coefficient k can also be calculated based on the size of the initial duty cycle D0 when the motor 10 is initially started. At this time, the calculation formula of the maximum limit duty cycle Dlim can be adjusted to Dlim=k(D0)*D1.

[0038] The following is an example of how to calculate the initial duty cycle when the motor 10 is initially started.

[0039] Method 1: When the motor 10 is initially started, the duty cycle output module 42 can output an initial duty cycle to drive the motor 10 to start, until the voltage across the motor 10 is constant at the target voltage U, and the output torque of the roller brush is constant at the target torque. The initial duty cycle is defined as De, then De = U / Ue, where U is the target voltage and Ue is the bus voltage of the power supply unit, that is, the nominal full pack voltage of the battery pack.

[0040] Mode 2: As another preferred embodiment of the present invention, the motor stall protection device further includes a power supply voltage detection unit 60, which is connected to the power supply unit 30 and the control module 44 respectively, and is used to detect the voltage across the power supply unit 30 in real time, that is, to detect the output voltage of the battery pack in real time. At this time, the duty cycle output module 42 can also output the initial duty cycle D0 to drive the motor 10 to start, until the voltage across the motor 10 is constant at the target voltage U. At this time, the calculation formula of the initial duty cycle D0 is: D0 = U / U0, where U is the target voltage, and U0 is the voltage across the power supply unit 30 detected in real time by the power supply voltage detection unit 60, that is, the real-time output voltage of the battery pack.

[0041] Of course, the calculation method of the initial duty cycle when the motor 10 is initially started may be other methods, which will not be described here with examples.

[0042] like Figure 3 As shown in FIG. 1 , it is a flow chart of the motor stall protection method of the present invention. It can be seen from the flow chart that the motor stall protection method of the present invention mainly includes the following steps:

[0043] S1, starting the motor 10 until the voltage across the motor 10 is constant at a target voltage U;

[0044] S2, the motor voltage detection unit 20 detects the voltage at both ends of the motor 10 in real time, and the PID voltage stabilization control module 41 performs PID regulation on the voltage at both ends of the motor 10, so that the motor 10 runs at a constant target voltage U;

[0045] S3, the duty cycle output module 42 outputs the real-time duty cycle D1, and transmits the real-time duty cycle D1 to the comparison module 43, the comparison module 43 compares the real-time duty cycle D1 with the preset maximum limit duty cycle Dlim, and transmits the comparison result to the control module 44;

[0046] S4. When the real-time duty cycle D1 is greater than the maximum limit duty cycle Dlim, the control module 44 outputs a control signal to the drive unit 50, and the drive unit 50 drives the motor 10 to shut down; when the real-time duty cycle D1 is less than or equal to the maximum limit duty cycle Dlim, the control module 44 outputs a control signal to the drive unit 50, and the drive unit 50 drives the motor 10 to continue running.

[0047] Specifically, step S1 is as follows: starting the motor 10 with an initial duty cycle until the voltage across the motor 10 is constant at a target voltage U. There are two ways to calculate the initial duty cycle: ① defining the initial duty cycle as De, then De=U / Ue, where U is the target voltage and Ue is the bus voltage of the power supply unit 30 connected to the motor 10; ② defining the initial duty cycle as D0, then D0=U / U0, where U is the target voltage and U0 is the output voltage of the power supply unit 30 connected to the motor 10.

[0048] Step S4 also includes: when the real-time duty cycle D1 is continuously greater than the maximum limit duty cycle Dlim within a set time period, the control module 44 outputs a control signal to the drive unit 50 to disconnect the electronic switch and power off the motor 10. Preferably, the set time period is 200ms to 1s. In other words, as long as the real-time duty cycle D1 is continuously greater than the maximum limit duty cycle Dlim within 200ms to 1s, no other judgment or operation is required, and the control module 44 directly controls the motor 10 to power off.

[0049] In short, the present invention uses an electronic switch to control the operation and power-off of the motor 10. After the motor 10 starts normally, the control unit 40 controls the electronic switch to perform pulse width modulation to control the output of the real-time duty cycle D1, so as to ensure that the motor 10 can operate at a constant target voltage U. On this basis, the control unit 40 determines whether the roller brush is blocked according to the size relationship between the real-time duty cycle D1 and the maximum limit duty cycle Dlim, and then when it is determined that the blockage occurs, it can quickly cut off the electrical connection between the power supply unit 30 and the motor 10, so that the motor 10 is powered off, which plays a good role in blocking protection.

[0050] To summarize, the motor stall protection device of the present invention compares the real-time duty cycle D1 output by the duty cycle output module 42 with the preset maximum limit duty cycle Dlim, and when the real-time duty cycle D1 is greater than the maximum limit duty cycle Dlim, the control module 44 promptly controls the motor 10 to shut down. This not only has a simple implementation method and low implementation cost, but also can achieve the maximum constant torque output of the motor 10 without triggering overcurrent protection, thereby achieving effective stall protection. In addition, while performing stall protection, it also effectively avoids the wear of the roller brush drive mechanism caused by overcurrent of the motor 10.

[0051] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present invention.

Claims

1. A motor stall protection device, characterized in that: include: Motor; A motor voltage detection unit, connected to the motor, for detecting the voltage across the motor in real time; A power supply unit, connected to the motor, and used to provide electrical energy to the motor; a control unit connected to the power supply unit and the motor voltage detection unit, configured to receive a voltage value detected by the motor voltage detection unit and output a control signal according to the voltage value; as well as A driving unit, connected to the power supply unit, the motor and the control unit, for driving the motor to operate or shut down according to a control signal output by the control unit; Wherein, the control unit includes a PID voltage stabilization control module, a duty cycle output module, a comparison module and a control module. The PID voltage stabilization control module is connected to the motor voltage detection unit and the control module, and is used to perform PID adjustment on the voltage across the motor after the motor is started, so that the motor runs at a constant target voltage; the duty cycle output module is connected to the control module and the comparison module, and is used to output a real-time duty cycle after the motor is started. The comparison module is used to compare the real-time duty cycle with a preset maximum limit duty cycle, and transmit the comparison result to the control module. When the real-time duty cycle is greater than the maximum limit duty cycle, the control module outputs a control signal to the drive unit to drive the motor to shut down; the target voltage is defined as U and the real-time duty cycle is defined as D1, then D1=U / Um, wherein Um is the voltage across the motor detected in real time by the motor voltage detection unit.

2. The motor stall protection device according to claim 1, characterized in that: The duty cycle output module is also used to output an initial duty cycle when the motor is initially started until the voltage across the motor is constant at a target voltage. The initial duty cycle is defined as De, then De=U / Ue, where U is the target voltage and Ue is the bus voltage of the power supply unit.

3. The motor stall protection device according to claim 1, characterized in that: The motor stall protection device also includes a power supply voltage detection unit, which is respectively connected to the power supply unit and the control module, and is used to detect the voltage across the power supply unit in real time; the duty cycle output module is also used to output an initial duty cycle when the motor is initially started until the voltage across the motor is constant at a target voltage, and the initial duty cycle is defined as D0, then D0=U / U0, wherein U is the target voltage and U0 is the voltage across the power supply unit detected in real time by the power supply voltage detection unit.

4. The motor stall protection device according to claim 3, characterized in that: The power supply unit is a battery pack, and U0 is the real-time output voltage of the battery pack.

5. The motor stall protection device according to claim 1, characterized in that: The maximum limit duty cycle is a fixed value.

6. The motor stall protection device according to claim 1, characterized in that: The maximum limit duty cycle=k*real-time duty cycle, wherein k is a critical coefficient and has a value range of 1.0 to 1.

5.

7. A motor stall protection method, applied to the motor stall protection device according to any one of claims 1 to 6, characterized in that: The motor stall protection method mainly comprises the following steps: S1, start the motor until the voltage across the motor is constant at the target voltage; S2, the motor voltage detection unit detects the voltage at both ends of the motor in real time, and the PID voltage control module performs PID regulation on the voltage at both ends of the motor to make the motor run at a constant target voltage; S3, the duty cycle output module outputs the real-time duty cycle, and transmits the real-time duty cycle to the comparison module, the comparison module compares the real-time duty cycle with the preset maximum limit duty cycle, and transmits the comparison result to the control module; S4. When the real-time duty cycle is greater than the maximum limit duty cycle, the control module outputs a control signal to the drive unit, and the drive unit drives the motor to shut down; when the real-time duty cycle is less than or equal to the maximum limit duty cycle, the control module outputs a control signal to the drive unit, and the drive unit drives the motor to continue running.

8. The motor stall protection method according to claim 7, characterized in that: The step S1 specifically includes: starting the motor with an initial duty cycle until the voltage across the motor is constant at a target voltage.

9. The motor stall protection method according to claim 8, characterized in that: The initial duty cycle is defined as De, then De=U / Ue, wherein U is the target voltage and Ue is the bus voltage of the power supply unit connected to the motor.

10. The motor stall protection method according to claim 8, characterized in that: The initial duty cycle is defined as D0, then D0=U / U0, wherein U is the target voltage and U0 is the output voltage of the power supply unit connected to the motor.

11. The motor stall protection method according to claim 7, characterized in that: The step S4 also includes: when the real-time duty cycle is continuously greater than the maximum limit duty cycle within a set time period, the control module outputs a control signal to the drive unit, and the drive unit drives the motor to shut down.

12. The motor stall protection method according to claim 11, characterized in that: The set time period is 200ms to 1s.

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