JP5016637B2 - Stepping motor step-out detection device - Google Patents

Description

  The present invention relates to a stepping motor step-out detection device that can effectively detect stepping motor step-out without using a sensor such as an encoder or a resolver.

  About the conventional stepping motor step-out detection device, the step-out detection circuit interposed in the output line of the driver is used to detect the motor current and the like, and the presence or absence of step-out is detected by monitoring the change appearing in this detection signal. (For example, there is Patent Document 1).

JP 2007-2336640 A

  However, a step-out detection circuit is provided on the output line of the driver, and a large motor current flows through the circuit. Therefore, the loss is large, and it is difficult to improve the efficiency of the motor and the like in this respect. However, when a device using a sensor such as an encoder or a resolver is used, the above problem is solved, but it causes another problem that it is difficult to reduce the cost of the device itself.

  The present invention was created under the above-described background, and the object of the present invention is to detect stepping motor step-out detection capable of achieving both high efficiency of the motor and the like and low cost of the apparatus. To provide an apparatus.

In order to solve the above problems, a stepping motor step-out detection device according to the present invention includes a voltage detection unit that pre-processes a voltage at a midpoint on the connection of each phase coil of the stepping motor and outputs the voltage as a midpoint voltage signal ; A step-out determination unit that monitors a change in the level, frequency, or waveform of the detection voltage of the midpoint voltage signal and determines whether or not the motor has stepped out and / or its sign based on the monitoring result. It has a configuration.

As a specific example of the step-out determination unit, a reference value necessary for determining the presence or absence of a stepping motor step-out or its sign is prepared in advance, and the level, frequency or waveform of the midpoint voltage signal and the reference There is a configuration in which the value is compared and the presence or absence of a step-out of the motor or its sign is determined based on the comparison result.

  The present invention described above is based on the following new findings. That is, when the stepping motor is out of step or close to it (including a high load state), a characteristic change appears in the voltage level, frequency or waveform at the midpoint on the connection of each phase coil of the motor. Therefore, if the change appearing in the voltage level of the middle point on the connection of each phase coil of the motor is monitored, it is determined whether or not the motor has stepped out or its sign (including a high load state). It becomes possible.

  Therefore, according to the present invention, even if the input side of the voltage detector is connected to the middle point on the connection of each phase coil of the stepping motor, a large current does not flow through the circuit, so the loss is very small. Thus, it is possible to increase the efficiency of the motor or driver. In addition, since the overall configuration of the apparatus is very simple, it is possible to easily reduce the cost.

When the use frequency band of the stepping motor is wide, it is preferable to use the following step-out determination unit. That is, the step-out determination unit prepares a reference value necessary for determining whether or not there is a stepping motor step-out or its sign in advance for each motor rotation speed category, and the motor rotation speed is input. Compares the level, frequency, or waveform of the midpoint voltage signal with the input reference value corresponding to the rotation speed of the motor, and determines whether the motor is out of step or its sign based on the comparison result It is configured to do.

  The invention of the subordinate concept described above is based on the following knowledge. That is, when the stepping motor is out of step or close to it, a characteristic change appears in the voltage level at the midpoint on the connection of each phase coil of the motor, but this phenomenon depends on the rotational speed of the motor. Change.

  Therefore, according to the invention of the subordinate concept described above, a reference value necessary to determine whether or not the stepping motor is out of step is prepared in advance for each rotation speed category of the motor, and the motor of the motor is selected from the reference values. Since the reference value corresponding to the actual rotational speed is used, it is possible to increase the detection accuracy of the step-out of the stepping motor even when the use frequency band of the stepping motor is wide. .

In determining whether or not the stepping motor is out of step or the like, it is preferable to use the following step out determination unit when monitoring the change in the voltage level of the midpoint on the connection of each phase coil of the motor. . That is, the step-out determination unit has a function of stopping determination of the presence or absence of step-out of the motor using the level of the midpoint voltage signal when the acceleration / deceleration of the motor is started. It is configured.

 The invention of the subordinate concept described above is based on the following knowledge. That is, at the start of acceleration / deceleration of the stepping motor, even if there is no step-out, the voltage level at the midpoint on the connection of each phase coil may increase.

 Therefore, according to the invention of the subordinate concept described above, when the acceleration / deceleration of the stepping motor is started, the determination of the presence or absence of step-out of the motor is stopped. Even in the case of acceleration / deceleration at the same time, it is possible to increase the detection accuracy such as step-out of the motor.

As for a specific example of the voltage detection unit in the case where one end or an intermediate part of each phase coil of the stepping motor is commonly connected as a middle point, the lead part electrically connected to the middle point and the lead part are guided through the lead part. It is preferable to have a configuration including an output unit that preprocesses the output midpoint voltage and outputs it as a midpoint voltage signal.

Regarding the specific example of the voltage detection unit when each phase coil of the stepping motor is connected in a ring shape and there is no midpoint on the connection of each phase coil, they are connected in a star shape corresponding to each phase coil. A midpoint circuit section, one end of which is connected to each connection point of each phase coil, and the other end on the common connection side in the midpoint circuit section is a midpoint on the connection of each phase coil. And a lead portion electrically connected to the lead portion and an output portion for pre-processing the midpoint voltage guided through the lead portion and outputting it as a midpoint voltage signal.

It is a block diagram of a stepping motor step-out detection device according to an embodiment of the present invention. It is a wave form diagram of the voltage of the middle point on the connection of each phase coil of the same stepping motor at the time of normal rotation of the stepping motor whose input frequency is 10 kHz. It is a wave form diagram of the voltage of the middle point on the connection of each phase coil of the same stepping motor at the time of step-out of the stepping motor whose input frequency is 10 kHz. It is a wave form diagram of the voltage of the middle point on the connection of each phase coil of the stepping motor at the time of step-out of the stepping motor whose input frequency is 1 kHz. It is a wave form diagram of the voltage of the middle point on the connection of each phase coil of the motor at the time of the rotation start of a stepping motor. It is a flowchart of the software processed by the step-out determination part of the same apparatus. It is a winding structure figure of a three phase star type stepping motor. It is a winding structure figure of a new 4-phase type stepping motor. It is a winding structure figure of a 5-phase star type stepping motor. It is a winding structure figure of a three phase delta type stepping motor. It is a winding structure figure of a 5-phase pentagon type stepping motor.

  A stepping motor step-out detection apparatus (hereinafter simply referred to as a step-out detection apparatus) according to an embodiment of the present invention will be described below with reference to FIGS. It should be noted that those for which the correspondence between the invention-specifying matters described in the claims and the components of the apparatus is unknown are shown together in the description of reference numerals described later.

  As for the out-of-step detection device 1 exemplified here, as shown in FIG. 1, a device capable of effectively detecting step-out of the stepping motor 2 or an indication thereof without using a sensor such as an encoder or a resolver. The voltage detection unit 10 and the step-out determination unit 20 are included.

  The stepping motor 2 includes a rotor 21, an A-phase coil 22, and a B-phase coil 23, and a winding structure in which intermediate portions of the A-phase coil 22 and the B-phase coil 23 are commonly connected as a middle point α. It has become. That is, the stepping motor 2 shown in FIG. 1 is a new two-phase stepping motor.

  The voltage detector 10 is a circuit for detecting the voltage at the midpoint α of the stepping motor 2, and is a lead wire electrically connected to the midpoint α between the stepping motor 2 and the device 1. The lead portion 11 to be connected and the output portion 12 that pre-processes the voltage at the midpoint α guided through the lead portion 11 and outputs it as a midpoint voltage signal a.

  As for the stepping motor 2, it is necessary to connect the lead part 11 to the A-phase coil 22 and the B-phase coil 23 and take it out to the outside. However, depending on the structure of the lead terminal of the motor, the lead part 11 may be You may not need to take it out. The same applies to the midpoint circuit portions 13 and 13 'described later.

  As for the output unit 12, a voltage dividing circuit 121 that divides the voltage at the middle point α and blocks a DC component, an amplitude limiting circuit 122 that is connected to the subsequent stage of the circuit 121, and a subsequent stage of the circuit 122. The operational amplifier amplifier circuit 123 is configured. The midpoint voltage signal a output from the operational amplifier amplifier circuit 123 is a signal obtained by pre-processing the voltage at the midpoint α into a form suitable for the processing of the step-out determination unit 20, but the level of the voltage at the midpoint α, The contents include information such as frequency and waveform.

  The step-out determination unit 20 determines whether or not there is a step out of the stepping motor 2 or its sign by inputting the analog-type midpoint voltage signal a and the digital rotation speed signal b, and uses the determination result as an alarm signal c. In this embodiment, a CPU (Central Processing Unit) is used.

  Note that the rotation speed signal b is a signal output from a driver (not shown) that generates a phase excitation signal by phase-distributing the input command pulse, and indicates the rotation speed command of the stepping motor 2. It shows substantially the same content as the frequency or rotational speed.

  2 to 5, the vertical axis represents the A / D conversion value of the midpoint voltage signal a, and the horizontal axis represents the sampling time. 2 shows a normal rotation of the motor with an input frequency of 10 kHz, FIG. 3 shows a step out of the motor with an input frequency of 10 kHz, FIG. 4 shows a step out of the motor with an input frequency of 1 kHz, and FIG. Each is shown.

  That is, when the stepping motor 2 steps out, a characteristic change appears in the voltage level, frequency, waveform, or the like of the midpoint α of the motor 2 as shown in FIG. This phenomenon also changes depending on the rotational speed of the motor 2 as shown in FIG. This is not greatly affected by the type of the motor 2 or the level of the drive current, and it has been confirmed by experiments that a phenomenon similar to the above appears even immediately before the step-out. Therefore, by constantly monitoring the voltage level, frequency, waveform, or the like at the middle point α while the motor 2 is being driven, it is possible to determine whether the motor 2 has stepped out or has an indication thereof. Based on such a principle, the step-out determination unit 20 determines whether the motor 2 is out of step or the like. In the present embodiment, in order to simplify the determination process of the step-out determination unit 20, the voltage level of the midpoint α is constantly monitored.

  However, as shown in FIG. 5, when the motor 2 starts rotating, the level of the voltage at the midpoint α becomes high even if there is no step-out or the like, and this may cause erroneous determination. Experiments have confirmed that this phenomenon does not depend on parameters such as the rotational speed command of the motor 2, self-starting or tilting, and the same phenomenon appears even when the motor 2 is re-accelerated from a constant speed and started to decelerate. ing. Therefore, the step-out determination unit 20 grasps the change in the rotation speed of the motor 2 based on the rotation speed signal b, and as a result, when the motor 2 starts acceleration or deceleration, The determination of the presence or absence of step-out or its sign is stopped to prevent erroneous determination.

  In the present embodiment, the out-of-step determination unit 20 prepares in advance a reference value necessary for determining whether the motor 2 is out of step for each rotation speed category of the motor 2. When the rotation speed is 1 kHz or more and less than 2 kHz, the reference value is 250 (first reference value) indicated by the A / D conversion value of the midpoint voltage signal a, and the rotation speed of the motor 2 is 2 kHz or more. In some cases, the reference value is 600 (second reference value) indicating the value of the A / D conversion value of the midpoint voltage signal a. Then, the A / D conversion value of the midpoint voltage signal a and the reference value corresponding to the rotation speed classification of the motor 2 are compared in magnitude, and the presence or absence of step-out of the motor 2 is determined based on the magnitude comparison result. It is a basic configuration for judging.

  The flow of the program specifically processed by the step-out determination unit 20 is as shown in FIG. However, in FIG. 6, the process of stopping the determination of the presence or absence of step-out of the motor 2 when the motor 2 starts acceleration or deceleration is omitted.

 First, the rotational speed command of the stepping motor 2 is input through the rotational speed signal b, the midpoint voltage signal a is A / D converted, and the voltage level of the midpoint α is input (processing 1). As a result, when the rotation speed of the motor 2 is 1 kHz or more and less than 2 kHz, processing 2 and processing 3 are performed, while when the rotation speed of the motor 2 is 2 kHz or more, processing 4 is performed. After completion of these processes, the process returns to the beginning again, and thereafter the loop process is repeated.

  In the process 2, the number of times that the A / D conversion value of the midpoint voltage signal a becomes 100 or less is counted, and when the count value reaches a predetermined number, the flag A is set. When the A / D conversion value of the midpoint voltage signal a exceeds the first reference value 250 in the state where the flag A is set, the flag B is set without immediately determining that the step-out has occurred.

  In the process 3, with the flag B set, the A / D conversion value of the midpoint voltage signal a is monitored a predetermined number of times, and when there is no 600 or more of the second reference value among them, It is determined that the motor 2 has stepped out because it is not an influence at the start of rotation of the motor 2, and the alarm signal c is activated. If there is a second reference value of 600 or more, the process 3 ends and the process returns to the beginning. The same applies when the flags A and B are in the reset state.

  In the process 4, the number of times that the A / D conversion value of the midpoint voltage signal a exceeds the second reference value 600 is counted. After the count up, when the A / D conversion value of the midpoint voltage signal a is 600 or less of the second reference value and the count indicates 1 to n, the influence at the start of rotation of the motor 2 is It is determined that the motor 2 has stepped out, and the alarm signal c is activated. When the A / D conversion value of the midpoint voltage signal “a” does not exceed the second reference value 600, the process 4 ends and returns to the beginning. The same applies when the A / D conversion value of the midpoint voltage signal a continuously exceeds the second reference value 600 after being counted up.

 Further, the out-of-step determination unit 20 prepares in advance another reference value necessary for determining whether or not there is a sign of out-of-step of the motor 2 for each rotation speed category of the motor 2, and is exactly the same as described above. With this method, it is determined whether or not there is a sign of step-out of the motor 2, and when it is determined that the motor 2 has a sign of step-out, the alarm signal c is activated.

The voltage indicating the step-out or high load state differs depending on the type of the stepping motor 2, the drive current value, etc., so that the motor 2 required to determine whether or not the step-out of the motor 2 is out of step or its sign is required. What is necessary is just to adjust suitably through experiment etc. about the number of rotation speed divisions, the reference value for every division, the frequency | count that the A / D conversion value of the midpoint voltage signal a exceeded the reference value, etc. Further, the harmonic component contained in the midpoint voltage signal a is detected by using a filter circuit or the like, the level of the detected harmonic component is compared with a reference value corresponding to the rotation speed of the motor 2, and the comparison The presence or absence of the step-out of the motor 2 or its sign may be determined based on the result.

The number of phases and winding structure of the stepping motor to which the step-out detection device 1 is applied are not limited to the new two-phase stepping motor shown in FIG. For example, a first type stepping motor in which one end of each phase coil is commonly connected as a midpoint (for example, a three-phase star type, a new four-phase type, a five-phase type shown in FIGS. 7, 8, and 9 respectively) In addition to the phase star type stepping motor, a second type stepping motor in which each phase coil is annularly connected (for example, the three-phase delta type and the five-phase pentagon type stepping shown in FIGS. 10 and 11, respectively) It can also be applied to motors.

  However, in the case of the second type stepping motor, there is no midpoint on the connection of each phase coil. For example, the three-phase delta stepping motor shown in FIG. A midpoint circuit unit 13 in which three resistors R are connected to each other in a star shape corresponding to each phase coil is provided, one end of the midpoint circuit unit 13 is connected to each connection point of each phase coil, and the common connection side The other end of the lead portion 11 is set as a middle point α, and the lead portion 11 is electrically connected. The same applies to the five-phase delta type stepping motor shown in FIG. 11, and a midpoint circuit unit 13 in which five resistors R having high resistance and the same resistance value are connected to each other in a star shape corresponding to each phase coil. ', And one end of the midpoint circuit portion 13' is connected to each connection point of each phase coil, and the other end on the common connection side is set as a midpoint α to electrically connect the lead portion 11.

  According to the step-out detection device 1 configured as described above, a large current does not flow through the lead portion 11 even if the lead portion 11 of the voltage detection portion 10 is connected to the middle point α of the stepping motor 2. However, the loss is very small, and in this respect, it is possible to increase the efficiency of the motor 2 or the driver. Moreover, since the applicable range of the stepping motor is very wide, it is highly versatile and very practical. In addition, since the overall configuration of the apparatus is very simple, it is possible to easily reduce the cost.

  The step-out detection apparatus according to the present invention may be integrated with a stepping motor driver or controller. As long as it has a function of detecting the voltage at the midpoint on the connection of each phase coil of the stepping motor and outputting the detected voltage to the step-out determination unit, the voltage detection unit may have any circuit configuration. The design may be changed as appropriate according to the configuration of the step-out determination unit. The step-out determination unit has a function of monitoring the detected voltage level, frequency, and / or waveform, etc. of the voltage detection unit in relation to the rotation speed of the motor to determine whether or not the motor has stepped out or its sign. The configuration is not limited as long as it is included, and the function may be realized by hardware. The rotation speed of the motor may be obtained by counting command pulses input to the driver or encoder signals output from the rotary encoder.

1 Step-out detection device (Stepping motor step-out detection device)
DESCRIPTION OF SYMBOLS 10 Voltage detection part 11 Lead part 12 Output part 20 Step-out determination part 2 Stepping motor 21 Rotor 22, 23 A phase coil, B phase coil alpha Midpoint (midpoint on connection of each phase coil)

Claims (6)

A voltage detection unit that pre-processes the midpoint voltage on the wiring of each phase coil of the stepping motor and outputs it as a midpoint voltage signal , and monitors changes in the level, frequency, or waveform of the midpoint voltage signal , A stepping motor step-out detection device comprising a step-out determination unit that determines step-out of the motor and / or the presence / absence of a sign thereof based on the monitoring result. The stepping motor step-out detection device according to claim 1, wherein the step-out determination unit prepares in advance a reference value necessary to determine whether or not the stepping motor has step-out or its sign, and the midpoint. Stepping motor step-out characterized by comparing the level, frequency, or waveform of the voltage signal with the reference value, and determining the step-out of the motor or the presence or absence of the sign based on the comparison result. Detection device. 2. The stepping motor step-out detection device according to claim 1, wherein the step-out determination unit has a reference value required for determining whether there is step-out of the stepping motor or the presence / absence of the stepping motor for each rotation speed of the motor. Prepared in advance, the rotational speed of the motor is input, the level, frequency or waveform of the midpoint voltage signal is compared with the reference value corresponding to the input rotational speed of the motor, and the comparison result A stepping motor step-out detection device characterized in that the step-out of the motor or the presence / absence of a sign thereof is determined based on the determination. 4. The stepping motor step-out detection device according to claim 3, wherein the step-out determination unit determines the level of the midpoint voltage signal when acceleration / deceleration is started based on the input rotational speed of the motor. A stepping motor step-out detection device having a function of stopping the determination of the presence or absence of step-out of the motor used. 4. The stepping motor step-out detection apparatus according to claim 1, wherein one end or an intermediate portion of each phase coil of the stepping motor is commonly connected as the middle point. A lead part electrically connected to the point, and an output part for pre-processing the midpoint voltage guided through the lead part and outputting it as a midpoint voltage signal. Stepping motor step-out detection device. In the stepping motor step-out detection apparatus according to claim 1, 2, or 3, wherein each phase coil of the stepping motor is connected in a ring shape and there is no midpoint on the connection of each phase coil. A group of resistors connected to each other in a star shape corresponding to each phase coil, one end of which is connected to each connection point of each phase coil, and a common connection side in the midpoint circuit unit The other end is a midpoint on the connection of each phase coil, and the lead portion electrically connected to the midpoint and the midpoint voltage guided through the lead portion are preprocessed and output as a midpoint voltage signal A stepping motor step-out detection device having a configuration including an output unit.

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