CN101383575A - Device and method for judging stop state of stepping motor - Google Patents

Abstract

A stepper motor stall state judgment device and judgment method are applied to a stepper motor with at least two stator windings and a rotor. The device mainly generates at least two continuous clock pulses of different phases to the at least two stator windings respectively through a driving module, so that the rotor rotates and the stator windings intermittently generate back electromotive force in sequence. Then, a control module with a preset threshold voltage alternately inputs a detection period to the driving module corresponding to the at least two continuous clock pulses of different phases, so that a detection module detects the back electromotive force generated by the at least two stator windings according to the detection period, and performs a comparison procedure between the back electromotive force and the threshold voltage. When the back electromotive force is lower than the threshold voltage, the control module judges that the stepper motor is in a stall state and outputs a stall state signal accordingly. In this way, not only can the problem of occupying the space of the original stepper motor control system by installing a micro switch can be avoided, but also the cost of mechanism design and additional components can be saved.

Description

Judgment device and method for stepping motor stop state

technical field

The present invention relates to a judging device and judging method for a stalled state of a stepping motor, more specifically, relates to a judging device and a judging method applied to a stepping motor with at least two stator windings and a rotor.

Background technique

Because of its very simple control method, stepping motor has been widely used in various control systems to control the speed, displacement and direction of the load device. The difference between the stepper motor and the general motor is that when the stepper motor receives power, the rotor (rotor) will not rotate periodically, that is, the stepper motor is a mechanical device that accepts digital signal control. , and the magnetic field of the pole (pole) on the stator (stator) is continuously switched alternately to drive the rotor to rotate, and whenever a digital clock signal pulse is input, the rotor of the stepper motor will rotate by a fixed angle, which is also That is, the known stepping angle. Since the stepper motor can directly receive the digital signal and produce a corresponding angle change, that is, the number of pulses is proportional to the output angle, so as long as it is within the controllable range, the stepper motor can be driven by an open loop , the control operation can be simply completed without considering the feedback (feedback).

Please refer to FIG. 1 , which is a schematic block diagram of a known stepping motor control system. As shown in the figure, the stepper motor control system 10 includes a control interface 11 , a control unit 12 , a drive unit 13 , a stepper motor 14 , and a power supply 15 . Wherein, the control interface 11 can be set in a computer system or a programmable logic controller (Programmable logic controller, PLC), and the control interface 11 is used to output a high-level command (high-level command) to the control unit 12, For example, the stepping motor system 10 is set in an optical disk drive to control an optical pick up head to perform track seeking operations. Therefore, the control interface 11 can directly input the track information to be accessed into the control unit 12, and then the control unit 12 generates a control signal correspondingly to control the drive unit 13, so that the drive unit 13 outputs current according to the control signal To drive the stepper motor 14, that is, use current to drive the coil (winding) winding on the stator electrode of the stepper motor 14 to generate the required magnetic field to drive the corresponding rotor, the optical read-write head installed on the rotor After locating to the desired track on the optical disc, the optical read/write head is then used to read the information on the track, and the current and power required by the drive unit 13 is provided by the power supply 15 .

But, in the stepping motor control technology of prior art, in order to further determine whether the rotor of stepping motor has rotated to the desired position, for example, determine whether the above-mentioned optical read-write head installed on the rotor of this stepping motor 14 is in It has been positioned at the initial position before reading the disc, and a micro switch is usually added to detect it. This undoubtedly occupies the space of the entire stepping motor control system, and correspondingly increases the cost of the mechanism design and the micro-switch.

Thus, how to provide a method that can save the cost of mechanism design and additional components (such as micro-switches), and can accurately judge whether the rotor of the stepping motor has rotated to the desired level without occupying the space of the original stepping motor control system. The judging device and judging method of the stalled state of the stepper motor in the position are actually problems to be solved urgently in the industry at present.

Contents of the invention

In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a judging device and method for a stalled state of a stepping motor, so as to simplify mechanism design and cost.

Another object of the present invention is to provide a judging device and method for determining whether the stepping motor is stalled by using a feedback method to detect whether the stepping motor is stalled.

In order to achieve the above and other objectives, the device for judging the stalled state of a stepping motor provided by the present invention is applied to a stepping motor with at least two stator windings and one rotor. The judging device of the stepping motor at least includes: a drive module, which is electrically connected to the at least two stator windings, respectively, to generate at least two continuous clock pulses of different phases, and make the stator windings sequentially through the rotation of the rotor Intermittently generate back electromotive force; a detection module, electrically connected to the drive module; and a control module, respectively electrically connected to the drive module and the at least two stator windings, for alternately corresponding to the at least two different phases in continuous time Pulse input detection period to the drive module, and preset a threshold voltage, so that the detection module detects the counter electromotive force generated by the at least two stator windings according to the detection period, so that when the detected counter electromotive force is low When the threshold voltage is lower, the control module judges that the stepping motor is in a stalled state, and outputs a stalled state signal accordingly.

Corresponding to the judging device of the stalled state of the stepping motor described above, the judging method of the stalled state of the stepping motor of the present invention comprises the following steps:

A first continuous clock pulse is sequentially generated and output to the first stator winding according to the first potential and the second potential.

A second continuous clock pulse is sequentially generated according to the first potential and the second potential and output to the second stator winding, wherein the second continuous clock pulse is in a different phase from the first continuous clock pulse.

When the phase of the first continuous clock or the second continuous clock is at the second potential, a detection period is input corresponding to the first continuous clock and the second continuous clock, so as to detect the If the back electromotive force generated by the first stator winding or the second stator winding through the rotation of the rotor is lower than a threshold voltage, it is judged that the stepper motor is in a stalled state, and a stalled state signal is output accordingly.

The judging device and judging method corresponding to the stalled state of the stepping motor described above, wherein the driving module alternately provides a high-impedance output corresponding to the at least two stator windings during the detection period, so that the corresponding generated counter electromotive force will not be caused by If it is too small, it is ignored, and it is misjudged as a stalled state.

Therefore, the present invention provides a judging device and judging method for a stepping motor stalled state, which is mainly by detecting the back electromotive force (BEMF) generated by a stepping motor when it is running, and by matching with a preset The reference voltage is compared to determine whether the stepper motor is in a stalled state. That is, when the detected counter electromotive force is lower than the reference voltage, it is judged that the stepper motor is in a stalled state, and a stalled state signal is output accordingly. Compared with the prior art, the present invention does not need to occupy the space of the original stepping motor control system, and can save the cost of mechanism design and additional components (such as micro-switches), thus achieving all the above-mentioned purposes.

Description of drawings

Fig. 1 is a schematic diagram of a block, which shows a schematic block diagram of the basic structure of a judging device of an existing stepping motor stall state;

Fig. 2 is a schematic diagram of a block, which shows a schematic block diagram of the basic structure of the judging device of the stalled state of the stepping motor of the present invention;

Fig. 3 is a detection timing diagram, which shows the stall detection timing diagram of the judging device for the stalled state of the stepping motor of the present invention;

Fig. 4 is a detection flow chart, in order to illustrate the detection flow chart of the judging device of stepping motor stall state of the present invention; And

FIG. 5 is a schematic block diagram, which is used to illustrate the implementation structure diagram of the device for judging the stalled state of the stepping motor of the present invention implemented in a data access device.

[Brief description of part designation]

10 Existing stepper motor system

11 Control Interface

12 Control unit

13 Drive unit

14 Stepper motor

15 Power Supply

20 Judging device

21 Driver Module

211 Clock generating unit

212 Drive unit

212a, 212b first output terminal

212c, 212d Second output terminal

212e, 212f input terminal

22 Detection Module

221 The first detector

222 Second detector

221a, 221b, 222a, 222b input terminals

23 Control Module

231 Analog-to-Digital Converter

30 Control Interface

40 data access device

50 Optical read/write head

A The first stator winding

B Second stator winding

R Rotor

A_in The first continuous clock

B_in Second Continuous Clock

U1_Out The first output signal

U2_Out Second output signal

S1～S5 Steps

Detailed ways

The implementation of the present invention is described below through specific specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various modifications and changes can be made to the details in this specification based on different viewpoints and applications without departing from the spirit of the present invention.

The following examples further illustrate the viewpoints of the present invention in detail, but do not limit the scope of the present invention in any respect.

Referring to FIG. 2 , it is a schematic block diagram illustrating the basic structure of the device for judging the stalled state of the stepping motor of the present invention. As shown in the figure, the judging device 20 at least includes: a driving module 21 , a detecting module 22 and a control module 23 . By detecting the back electromotive force (Back ElectroMotive Force; BEMF) generated by the stepper motor when it is running, it is judged whether it is in a stalled state, and a stalled state signal is output accordingly. In this embodiment, the stepping motor includes a first stator winding A, a second stator winding B and a rotor R, but this application takes a two-phase stepping motor as an example, in fact the stator winding is not in the form of This is the limit, that is, any even number and the number of phases of multiples thereof.

The driving module 21 includes a clock generating unit 211 and a driving unit 212 . The drive unit 212 has first output terminals 212a, 212b and second output terminals 212c, 212d, wherein the first output terminals 212a, 212b are used to electrically connect the first stator winding A, the second output terminals 212c, 212d is used to electrically connect the second stator winding B; the clock generating unit 211 is electrically connected to the driving unit 212 to generate continuous clocks of different phases to the first stator winding A and the second stator winding B respectively .

The detection module 22 includes a first detector 221 and a second detector 222 . The input ends 221a, 221b of the first detector are respectively electrically connected to the first output ends 212a, 212b of the drive unit 212 connected to the first stator winding A; the input ends 222a, 212b of the second detector 222 222b is respectively electrically connected to the second output terminals 212c and 212d of the drive module 212 and the second stator winding B to detect the back electromotive force (BEMF) of the first stator winding A or the second stator winding B. ).

The control module 23 is electrically connected to the output end 221c of the first detector 221 and the output end 222c of the second detector 222 respectively. And the control module 23 is electrically connected to one of the input terminals 212e of the driving module 212 through the output terminal 221c, and is electrically connected to the other input terminal 212f of the driving module 212 through the output terminal 222c, A detection period is alternately input to these continuous clock pulses of different phases, so as to respectively detect the back electromotive force (BEMF) outputted by the first stator winding A or the second stator winding B. And the control module presets a threshold voltage (Threshold voltage), and performs a comparison procedure with the back electromotive force (BEMF), so that when the detected back electromotive force (BEMF) voltage is higher than the preset threshold voltage, the control module 23 immediately judges The stepping motor is in a running state, and outputs a running state signal accordingly; and when the detected back electromotive force (BEMF) voltage is lower than a preset threshold voltage, the control module 23 judges that the stepping motor is in a stalled state, And correspondingly output a stall state signal, wherein the drive module alternately provides a high-impedance output corresponding to the at least two stator windings during the detection period, so that the correspondingly generated counter electromotive force will not be ignored due to too small, and Misjudged as stalled state.

In addition, the control module 23 also includes an analog-to-digital converter 231 (Analog to digital converter), which is used to convert the analog signals generated by the first detector 221 and the second detector 222 of the detection module 22 into digital Data stream is used to output these continuous status signals to a system (not shown).

Referring to FIG. 3 , it is used to illustrate the detection timing diagram of the judging device for the stalled state of the stepping motor of the present invention, to respectively display the signal states of the detected input terminals 212e, 212f of the drive module 21 and the output terminal of the control module 23. As shown in the figure, the continuous clock pulse generated by the driving module 21 is a continuous phase of a first potential (preset to 5V and 0V in this embodiment) and a second potential (preset to 2.5V in this embodiment) Combination, that is, when the clock generating module sequentially generates a first continuous clock A_in according to the first potential and the second potential and outputs it to the first stator winding A, it will be delayed by one phase according to the aforementioned first A potential and the second potential sequentially generate a second continuous clock B_in to be output to the second stator winding B, and the first stator winding A generates a first output signal U1_Out correspondingly through the first detector 221 , the second stator winding B correspondingly generates a second output signal U2_Out through the second detector 222, for alternately corresponding to the first continuous clock A_in and the second continuous clock B_in to input a detection period , and perform a comparison procedure between the counter electromotive force and the threshold voltage.

The comparison procedure includes the following steps:

(1) When the timing of these continuous clock pulses is T3, the second stator winding B outputs the first potential to make the rotor R run, so that the first stator winding A adjacent to the second stator winding B relatively outputs the second potential , that is, no current flows through the first stator winding A, and the rotation of the rotor R causes the first stator winding A to relatively generate a back electromotive force (BEMF) greater than the threshold voltage in the T3 phase of the second output signal U1_Out. It shows that the stepper motor is still running.

(2) When the timing of these continuous clock pulses is T4, the first stator winding A outputs the first potential to make the rotor R run, and the second stator winding B outputs the second potential, that is, the second stator winding B has no The current flows through the rotor R to make the second stator winding B relatively generate a back electromotive force (BEMF) greater than the threshold voltage in the T4 phase of the first output signal U2_Out, which indicates that the stepping motor is still in the running state.

(3) When the timing of these continuous clocks is T7, the first stator winding A outputs the second potential, and the second stator winding B outputs the first potential, but since the first stator winding A is in the second No back electromotive force (BEMF) is generated or the generated back electromotive force (BEMF) is less than the threshold voltage in phase T7 of an output signal U1_Out, so it indicates that the stepping motor is in a stalled state at this time.

Referring to FIG. 4 , it is used to illustrate the detection flow chart of the device for judging the stalled state of the stepping motor of the present invention. As shown in the figure, first define a first potential and a second potential in step S1, and preset a memory segment in the output system, which defines a stepper motor stop flag (Motor stop flag ), when the stepper motor is still running, it will be displayed as "Lo" (low potential), and when the stepper motor is stopped, it will be displayed as "Hi" (high potential), and then go to step S2.

In step S2, a continuous clock is generated according to the aforementioned first potential and second potential respectively. Specifically, a first continuous clock A_in is sequentially generated according to the aforementioned first potential and second potential and output to the first stator winding A, and a second continuous clock A_in is sequentially generated according to the aforementioned first potential and second potential. The continuous clock B_in is output to the second stator winding B, so that when the second continuous clock lags behind the first continuous clock by an odd phase, the first continuous clock A_in and the second continuous clock B_in are alternately input with one detection period, and perform a comparison process between the back EMF and the threshold voltage.

In step S3, the back electromotive force (BEMF) of the second stator winding B is detected, and it is judged whether the back electromotive force (BEMF) generated by the second stator winding B is greater than the threshold voltage, that is, when the phase of the first continuous clock A_in is at When the phase of the second continuous pulse B_in is at the first potential and the phase of the second continuous pulse B_in is at the second potential, detect the back electromotive force (BEMF) generated by the second stator winding B and judge accordingly whether it is greater than the threshold voltage, if so, proceed to step S4, if If not, go to step S5.

In step S4, the back electromotive force (BEMF) of the first stator winding A is detected, and it is judged whether the back electromotive force (BEMF) generated by the first stator winding A is greater than the threshold voltage, that is, when the first continuous clock pulse A_in When the phase is at the second potential and the phase of the second continuous clock B_in is at the first potential, detect whether the back electromotive force (BEMF) generated by the first stator winding A is greater than the threshold voltage, if so, return to step S2, if not , then go to step S5.

In step S5, change the stop flag of the stepper motor to "Hi" to show that the stepper motor is in a stalled state, wherein the detection periods alternately provide a high impedance output corresponding to the at least two stator windings, So that the counter electromotive force generated accordingly will not be ignored and misjudged as a stalled state because it is too small.

Referring to FIG. 5 , it is a schematic diagram illustrating the implementation structure of the device for judging the stalled state of the stepping motor of the present invention implemented in the data access device. As shown in the figure, the judging device 20 is electrically connected to the first and second stator windings A and B of the stepper motor 14 through the drive module 21 and the detection comparison module 22 respectively as in the above-mentioned embodiment, and is powered by the power supply. 15. In addition to providing the drive current and power required by the drive module 21, it also includes a control interface 30, a data access device 40, and an optical pick up head 50 (optical pick up header) mounted on the data access device 40, wherein the control interface 30 The judging device 20 and the optical read-write head 50 are respectively electrically connected, the optical read-write head 50 is arranged on the rotor R of the stepping motor, and the data access device 40 can be CD-ROM, DVD or Combo .

When the phase of the first continuous clock A_in or the second continuous clock B_in is at the second potential, sequentially detect and compare the counter electromotive force generated by the first stator winding A or the second stator winding B through the rotation of the rotor R, and A comparison procedure of the back EMF and the threshold voltage is performed. If the counter electromotive force is lower than the threshold voltage, the judging device 20 judges that the stepper motor is in a stalled state, and outputs a status signal to the control interface 30 accordingly, so that the control interface 30 correspondingly inputs a read and write command control signal to the The optical read-write head 50, so that the optical read-write head 50 starts to read and write the data access device 40, therefore, not only can avoid the known need to install micro-switches in addition to occupy the original stepping motor control system The problem of space can save the cost of mechanism design and additional components (such as: micro-switch).

In summary, the present invention provides a judging device and method for the stopped state of a stepping motor. Compared with the set threshold voltage to judge whether the stepping motor is in a stalled state, that is, when the detected back electromotive force is lower than the threshold voltage, it is judged that the stepping motor is in a stalled state, and a corresponding output is in a stalled state Signal, compared with the prior art, the present invention does not need to occupy the space of the original stepping motor control system, and can save the cost of mechanism design and additional components (such as: micro-switch).

The above-mentioned embodiments only illustrate the principles and effects of the present invention, but are not intended to limit the present invention. Any person familiar with the art can modify and change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be listed in the claims.

Claims (13)

1. A judging device for a stepping motor stalled state, applied to a stepping motor with at least two stator windings and a rotor, the judging device for a stepping motor stalled state at least includes: The drive module is electrically connected to the at least two stator windings, and is used to generate at least two continuous clock pulses of different phases to the at least two stator windings, so as to make the rotor run and make the at least two stator windings sequentially Intermittent generation of counter electromotive force; a detection module, electrically connected to the driving module and the at least two stator windings, for detecting the counter electromotive force generated by the at least two stator windings; and The control module is electrically connected to the driving unit and the detection module, and is used to alternately input a detection period corresponding to the at least two continuous clock pulses with different phases to the driving module, and a threshold voltage is preset so that the The detection module detects the counter electromotive force generated by the at least two stator windings according to the detection period, and performs a comparison procedure between the counter electromotive force and the threshold voltage, so that when the counter electromotive force is lower than the threshold voltage, the control module That is, it is judged that the stepping motor is in a stalled state, and a stalled state signal is output accordingly. 2. the judging device of stepping motor stall state as claimed in claim 1, wherein, this drive module comprises at least: a clock generation unit for generating continuous clocks; and The drive unit is electrically connected to the clock generation module, the control module and the at least two stator windings, and is used to excite one of the stator windings according to the continuous clock pulse, so that the rotor rotates to generate a Counter electromotive force. 3. The device for judging the stalled state of a stepping motor as claimed in claim 1, wherein, during the detection period, the driving module alternately provides a high impedance output corresponding to the at least two stator windings. 4. The device for judging the stalled state of a stepping motor as claimed in claim 1 or 2, wherein any two consecutive clock pulses with different phases have an odd phase difference. 5. The device for judging the stopped state of a stepping motor according to claim 1 or 2, wherein the continuous clock pulses are a continuous phase combination of a first potential and a second potential. 6. The device for judging the stopped state of a stepping motor as claimed in claim 5, wherein the first potential is a positive or negative potential. 7. The judging device of the stalled state of the stepping motor as claimed in claim 5, wherein the second potential is used to generate an intermittent sequence for the detection module to detect the reaction of the corresponding stator winding due to the rotation of the rotor. electromotive force. 8. The device for judging the stalled state of the stepping motor as claimed in claim 1, wherein the stepping motor is mounted on an optical read/write head of the data access device. 9. A method for judging the stalled state of a stepping motor, applied to a stepping motor with at least two stator windings and a rotor, the method for judging the stalled state of the stepping motor comprises the following steps: sequentially generating a first continuous clock pulse output to the first stator winding according to a first potential and a second potential; sequentially generating a second continuous clock pulse and outputting it to the second stator winding according to a first potential and a second potential, wherein the second continuous clock pulse is out of phase with the first continuous clock pulse; When the phase of the first continuous clock or the second continuous clock is at the second potential, a detection period is input corresponding to the first continuous clock and the second continuous clock, so as to detect the If the back electromotive force generated by the first stator winding or the second stator winding through the rotation of the rotor is lower than a threshold voltage, it is judged that the stepping motor is in a stalled state, and a stalled state signal is output accordingly. 10 . The method for judging a stalled state of a stepping motor as claimed in claim 9 , wherein the detection periods alternately provide a high-impedance output corresponding to the at least two stator windings. 11 . 11. The method for judging the stop state of a stepping motor as claimed in claim 9, wherein the phase difference between the first continuous clock pulse and the second continuous clock pulse is an odd number. 12. The method for judging the stalled state of the stepping motor as claimed in claim 9, wherein the first potential is a forward or reverse potential. 13. The method for judging the stalled state of a stepping motor as claimed in claim 9, wherein the second potential is used to generate an intermittent sequence for the first stator winding or the second stator winding corresponding to the detection. The counter electromotive force generated by the rotation of the rotor.

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