JP4997631B2 - Stepping motor step-out determination device and step-out determination method - Google Patents

Description

  The present invention relates to a step-out determination apparatus and a step-out determination method for a stepping motor that is step-driven by sequentially energizing a plurality of exciting coils in accordance with a clock signal.

  Conventionally, there has been proposed a method for determining step-out of a stepping motor without providing a detector such as an encoder. For example, in Patent Documents 1 and 2, the detection waveform is input from the current path of the exciting coil, and the level data of the detection waveform is sampled at a predetermined timing starting from the rising or falling edge of the clock signal. A method for determining the step-out of the stepping motor based on this is described. Specifically, in the step-out determination method of Patent Document 1, the voltage level of the detected waveform is compared with a preset reference voltage by a comparator, and when the voltage level of the detected waveform exceeds the reference voltage, the stepping motor Is determined to be out of step. Further, in the step-out determination method of Patent Document 2, the detected waveform and the reference waveform are compared based on a plurality of level data sampled at a predetermined sampling period, and when the detected waveform does not match within a predetermined error, It is determined that the stepping motor is out of step.

However, although the step-out determination method shown in Patent Documents 1 and 2 seems to be effective when used at room temperature such as a printer, it is used in an environment where the temperature changes rapidly such as an air conditioner. If this is attempted, it may be impossible to determine the stepping motor step-out or it may be erroneously determined to be step-out. That is, since the voltage level of the detected waveform varies according to the temperature change, it is difficult to accurately determine the step out of the stepping motor in comparison with a constant reference voltage or a constant reference waveform.
JP 63-87198 A JP-A-11-225499

  The present invention was devised in order to eliminate the above-described problems, and is capable of discriminating stepping motor step-out without providing a detector such as an encoder, but almost ignores temperature characteristics. It is possible to provide a stepping motor step-out determination device and a step-out determination method capable of accurately determining stepping motor step-out under a wide range of temperature environments (for example, −20 ° C. to + 50 ° C.). With the goal.

In order to solve the above problems, a stepping motor step-out determination device according to the present invention is a stepping motor step-out determination device that is step-driven by sequentially energizing a plurality of excitation coils in accordance with a clock signal, Detection waveform input means for inputting a detection waveform for each step drive from the combined current path of the excitation coil, sampling means for sampling the level data of the detection waveform at a predetermined timing starting from the rising or falling edge of the clock signal, and this time The difference calculation means for calculating the difference between the level data of the input detected waveform and the level data of the detected waveform input previously or before is compared with the absolute value of the calculated difference and a preset step-out discrimination value. When the difference comparison means and the calculated difference exceed the step-out determination value, it is determined that the stepping motor is out of step. And a step-out determination means that, in the detected waveform input means, based on the energization pattern of the exciting coils, and inputted to sequentially said sampling means a detected waveform of the synthesized current supplied to each input of the clock signals, The sampling means detects a set of detected waveforms to be compared among the input detected waveforms, samples a plurality of level data at a predetermined sampling period from each of the detected waveforms that form the set, and repeats this. In addition, the difference calculation means calculates the difference between the level data of the detection waveform input this time and the level data of the detection waveform input previously or before that time by the number of samplings in order to compare the detection waveforms in the set. In the difference comparison means, by comparing the sum of absolute values of the plurality of calculated differences with a preset step-out determination value, Serial characterized that you discriminated by step-out determination means.
In order to solve the above problem, the stepping motor step-out determination method of the present invention is a stepping motor step-out determination method that is step-driven by sequentially energizing a plurality of excitation coils in accordance with a clock signal. , Sequentially inputting a detection waveform of a combined current energized every step drive from the combined current path of the exciting coil, and detecting a detected waveform to be compared among the input detection waveforms as a set, A plurality of detection waveform level data are sampled at a predetermined timing starting from the rising or falling edge of the clock signal at a predetermined sampling period from each of the detection waveforms to be detected , and this is repeated, and the detection waveforms that form the set in order to compare the level data of the level data and the previous or earlier entered detected waveform of currently inputted detected waveform Calculates the difference only sampling number of times, compared with the step-out determination value that is beforehand set to the sum of the absolute value of the computed difference, when the calculated difference exceeds the out-decision value, the stepping motor is out of step It is characterized by distinguishing that it is.

Since the present invention is configured as described above, the stepping motor step- out is discriminated using the detection waveform of the composite current input for each clock signal without providing a detector such as an encoder. However, focusing on the fact that there are variations in the detection waveform of each composite current for each input, the combination of the composite currents to be compared among these input detection waveforms is exemplified as “Excitation coils 11, 14” → “Excitation coils 12 and 13” → “Excitation coils 11 and 14” → “Excitation coils 12 and 13”..., The same phase is repeatedly detected with a single combination, and predetermined sampling is performed from each detection waveform. A plurality of level data is sampled at a period, and the difference between them is calculated by the number of times of sampling. In consideration of the variation of the composite current for each phase (each excitation coil), “(D1′−D1) + (D2′−D2) + (D3′−D3)> step-out determination value” Step-out discrimination can be performed with simple arithmetic processing, and as a result, the detection waveform input this time and the detection waveform input before or before this time are avoided, avoiding the inconvenience that the discrimination accuracy decreases due to variations in the composite current in each phase. Can be compared with high accuracy, and the difference is hardly affected even if the voltage level of the detected waveform fluctuates according to the temperature change. Therefore, the temperature characteristics can be almost ignored. Based on the comparison result, it is possible to accurately determine the step-out of the stepping motor in a wide temperature environment (for example, −20 ° C. to + 50 ° C.).

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A stepping motor step-out determination apparatus and a step-out determination method that exemplify embodiments of the present invention as preferred embodiments will be described below in detail with reference to the drawings. FIG. 1 is a circuit diagram showing a stepping motor and a step-out discrimination device. As shown in this figure, the stepping motor 10 has a plurality of exciting coils (windings) 11 to 14 and is step-driven by sequentially energizing these exciting coils 11 to 14. Yes. Switching of the current to be passed through the exciting coils 11 to 14 can be performed using a general-purpose drive IC 20. The drive IC 20 includes transistors 21 to 24 corresponding to the number of exciting coils 11 to 14, and sequentially switches the transistors 21 to 24 in a predetermined combination in accordance with a clock signal input from the oscillator 30. The stepping motor 10 is step-driven at a speed corresponding to the cycle of the clock signal.

  The step-out determination device 40 includes a detection circuit 41 and a determination unit 42. The detection circuit 41 is connected to a combined current path of the exciting coils 11 to 14, and a detection waveform for each step drive is extracted from the detection circuit 41 and input to the determination unit 42. Specifically, a detection resistor RS of about 1Ω is provided to branch the combined current path, and is connected to the input unit of the determination unit 42 via an operational amplifier or the like. The determination unit 42 is configured by using, for example, a one-chip microcomputer, and an A / D conversion circuit (detection waveform input means) that inputs a detection waveform for each step drive, a CPU that operates according to a predetermined program, a program And a RAM serving as a program execution area. By executing a step-out determination process, which will be described later, the sampling means, the difference calculation means, the difference comparison means, and the removal described in the claims. It functions as a key discrimination means.

  FIG. 2 is a timing chart showing an energization pattern of the exciting coil in the stepping motor. As shown in this figure, in the two-layer stepping motor 10, the exciting coils 11 and 14 are energized at the first rise of the clock signal. At this time, the combined current of the exciting coils 11 and 14 flows through the combined current path, and the detected waveform a is observed. When the second clock signal is input, the energization of the exciting coil 11 is cut off while the energizing of the exciting coil 11 is maintained, and the exciting coil 12 is energized. At this time, the combined current of the exciting coils 11 and 12 flows through the combined current path, and the detected waveform b is observed. When the third clock signal is input, the energization of the excitation coil 12 is interrupted while the energization of the excitation coil 12 is maintained, and the excitation coil 13 is energized. At this time, the combined current of the exciting coils 12 and 13 flows through the combined current path, and the detected waveform c is observed. Further, when the fourth clock signal is input, the energization to the excitation coil 13 is maintained while the energization to the excitation coil 12 is cut off and the excitation coil 14 is energized. At this time, the combined current of the exciting coils 13 and 14 flows through the combined current path, and the detected waveform d is observed. Thereafter, the same energization pattern is repeated, and the detected waveforms a ′, b ′, c ′, d ′, a ″, b ″, c ″, d ″.

  FIG. 3A is a waveform diagram showing temperature characteristics of a detected waveform, and FIG. 3B is a waveform diagram showing a sampling cycle of level data. As shown in these figures, the detection waveforms a to d have temperature characteristics, and the voltage level is high at a low temperature, and the voltage level is low at a high temperature. The step-out determination device 40 of the present invention can determine the step-out of the stepping motor 10 without providing a detector such as an encoder, but can almost ignore such temperature characteristics. This makes it possible to accurately determine the step-out of the stepping motor 10 under a wide range of temperature environments (for example, −20 ° C. to + 50 ° C.). The method will be specifically described.

  The step-out determination device 40 inputs a detection waveform for each step drive from the combined current path of the excitation coils 11 to 14, samples the level data D ′ of the detection waveform at a predetermined timing starting from the rising edge of the clock signal, The difference between the level data D ′ of the detection waveform input this time and the level data D of the detection waveform input before or before is calculated, and the absolute value of the calculated difference is compared with a preset step-out determination value. When the calculated difference exceeds the step-out determination value, it is determined that the stepping motor 10 is out of step. That is, the difference between the level data D ′ of the detection waveform input this time and the level data D of the detection waveform input before or before the detection waveform is changed even if the voltage level of the detection waveforms a to d fluctuates according to the temperature change. Since the influence is not so much, even in the stepping motor 10 used for, for example, air-conditioning valve control in a wide temperature environment, the step-out can be accurately determined.

  When applying the above-described step-out determination method, as shown in FIG. 3, a plurality of (for example, three) level data D1 to D3 are sampled from a single detected waveform at a predetermined sampling period and inputted this time. The difference between the level data D1 ′ to D3 ′ of the detected waveform and the level data D1 to D3 of the detected waveform input the previous time or before is calculated as many times as the number of samplings, and the sum of the absolute values of the calculated differences is set in advance. It is preferable to determine the step out of the stepping motor 10 by comparison with the step out determination value. In this way, it is possible to compare the detection waveform input this time with the detection waveform input before or before the time with high accuracy and accurately determine the step-out of the stepping motor 10 based on the comparison result.

  When the stepping motor 10 is a two-phase stepping motor, it is preferable to sample the level data D1 to D3 from every other detected waveform as shown in FIG. In this way, it is possible to avoid the inconvenience that the discrimination accuracy decreases due to variations in the combined current in each phase. For example, when level data D1 to D3 are sampled from the respective detection waveforms a to d shown in FIG. 2, the combination of the combined currents to be compared is “excitation coils 11, 14” → “excitation coils 11, 12” → “excitation coils”. 12, 13 ”→“ excitation coils 13, 14 ”... Change in a plurality of combination patterns, but when level data D1 to D3 are sampled from every other detected waveform a, c, comparison is made The combination of the combined currents is one combination such as “excitation coils 11, 14” → “excitation coils 12, 13” → “excitation coils 11, 14” → “excitation coils 12, 13”. In addition, one step-out determination value can be set in consideration of the variation of the combined current in each phase, so that step-out determination with high accuracy can be performed.

  Further, it is preferable that the sampling period and the step-out determination value can be changed automatically or manually. For example, during normal operation, the sum (absolute value) of the difference between the sampled level data D1 to D3 is substantially constant, and when the step-out occurs, the sum (absolute value) of the difference between the sampled level data D1 to D3 changes drastically. Select a sampling period. In addition, when the step-out determination value is changed, it is possible to adjust the sensitivity of the step-out determination according to the application and environment to be used. In addition, when a frequency filter for determining the number of times that the step-out determination value has been exceeded is provided and a step-out determination signal is output in accordance with the determination of the frequency filter, the step-out determination is performed by changing the number of determinations of the frequency filter The sensitivity can be adjusted.

  Further, when applying the above-described step-out determination method, it is preferable that the period from the start of the stepping motor 10 until a predetermined time elapses is set as the step-out determination prohibition period. In this way, it is possible to ignore the disturbance of the detected waveform at the time of activation and prevent erroneous step-out determination. In the step-out determination prohibition period, it is also possible to read the clock signal and automatically change the sampling period based on the clock signal. For example, the sampling period is automatically changed so that the sampling period is long when the clock period is long, and the sampling period is also short when the clock period is short. In this way, it is possible to acquire the level data of the detected waveform at an appropriate sampling period regardless of the period of the clock signal, and to perform step-out determination with high accuracy.

  Next, specific step-out determination processing for realizing the step-out determination method as described above will be described with reference to FIG. FIG. 4 shows a step-out determination processing procedure when comparing detected waveforms every time. However, when comparing every other detected waveform, every other rising edge of the clock signal is compared in step S1. May be detected.

  FIG. 4 is a flowchart of the step-out determination process. As shown in this figure, the discriminating unit 42 of the step-out discriminating device 40 sequentially determines the rise of the clock signal (S1). If the determination result is YES, after the timer Δt, which is the sampling period, is counted (S2), the level data Dn ′ of the detected waveform is sampled (S3), and the absolute value of the difference from the previous level data Dn is calculated. And temporarily store it (S4). Next, it is determined whether or not the sampling number n has reached a specified number (for example, 3) (S5). If the determination result is NO, the above steps S2 to S5 are repeated. On the other hand, when the specified number of samplings is reached, it is determined whether or not it is a start-up (step-out determination prohibition period) (S6). If the determination result is YES, the sampling cycle automatic change process (S7) is being executed. The above steps S1 to S6 are repeated. The step-out determination prohibition period can be defined by the number of rises of the clock signal after startup. Further, as described above, the sampling cycle automatic change processing is processing for automatically optimizing the sampling cycle (timer Δt) according to the clock cycle.

  When the step-out determination prohibition period ends, the difference data temporarily stored in step S4, that is, the difference between the level data D1 ′ to D3 ′ of the currently input detection waveform and the level data D1 to D3 of the previously input detection waveform is absolute. With reference to the value, the sum is calculated, and the difference sum is compared with the step-out discrimination value (S8). Then, the comparison result is determined (S9), and if the sum of the differences does not exceed the step-out determination value, the process returns to step S1 as it is and repeats the sequential comparison of the detected waveforms, but the sum of the differences exceeds the step-out determination value. In this case, it is determined that the stepping motor 10 is out of step, and a step-out detection signal is output (S10).

In the embodiment of the present invention configured as described above, the step-out discriminating device 40 detects the step-out of the stepping motor 10 without providing a detector such as an encoder , and the combined current input for each clock signal. The detection waveform is discriminated. The detection waveform of the combined current energized every step drive is sequentially input from the combined current path of the exciting coils 11 to 14, and each of the input detection waveforms a to d is input. Among them, the detected waveforms (a, c) to be compared are detected as a set as illustrated, and the rising edge of the clock signal is started from each of the detected waveforms (a, c) in the set at a predetermined sampling period. multiple sampled level data D 'of the detection waveform (c) at a predetermined timing, performs repeating this, the set become detected waveform (a, c) in order to compare, currently inputted detected waveform (c ) And the level data D of the detected waveform (a) input at the previous time or before is calculated as many times as the number of samplings , and the absolute value of the calculated difference and a preset step-out discrimination value are calculated. When the calculated difference exceeds the step-out determination value, it is determined that the stepping motor 10 is out of step.
Focusing on the variation in the detection waveforms a to d of each combined current for each input, and taking into account the variation of the combined current for each phase (each excitation coil), among these input detection waveforms, The combination of the composite currents to be compared is a detection waveform (excitation coil 11, 14) → excitation coil 12, 13 → excitation coil 11,14 → excitation coil 12, 13 ... The same phase is repeatedly detected with one combination of a, c), a plurality of level data Dn are sampled at a predetermined sampling period from each detected waveform (a, c), and the difference between the two is sampled. For the level data of the detected waveforms (a, c) that form a set as shown in FIG. 4 that is calculated only by the amount, “(D1′−D1) + (D2′−D2) + (D3′−D3) ) ＞ Step out Step out can be determined by simple arithmetic processing such as “value”. As a result, the detection waveform (c) input this time and the previous time or it can be avoided by avoiding the disadvantage that the determination accuracy decreases due to variations in the combined current in each phase. The previously input detection waveform (a) can be compared with high accuracy, and the difference is not significantly affected even if the voltage levels of the detection waveforms a to d fluctuate according to the temperature change. , it is possible to largely ignored the temperature characteristic, based on the comparison result a wide temperature environment (e.g., -20 ℃ ~ + 50 ℃) can be carried out step-out determination of a good stepping motor with precision.

  In addition, a plurality of (for example, three) level data D1 to D3 are sampled from a single detected waveform at a predetermined sampling period, and the level data D1 ′ to D3 ′ of the detection waveform input this time and the previous time or earlier are input. The difference between the level data D1 to D3 of the detected waveform is calculated as many times as the number of samplings, and the stepping motor 10 is stepped out by comparing the sum of the absolute values of the calculated plural differences with a preset step-out determination value. Therefore, it is possible to compare the detection waveform input this time with the detection waveform input before or before this time with high accuracy, and to accurately determine the step-out of the stepping motor 10 based on the comparison result.

  Further, when the stepping motor 10 is a two-phase stepping motor, the level data D1 to D3 are sampled from every other detected waveform, so that the discrimination accuracy is reduced due to the variation of the composite current in each phase. To avoid inconvenience.

  In addition, since the sampling period and step-out determination value can be changed, not only can the step-out determination accuracy be improved by optimizing the sampling period, but also the sensitivity of step-out determination can be improved by changing the step-out determination value. It becomes possible to adjust arbitrarily.

  In addition, since the period from when the stepping motor 10 is activated until the predetermined time elapses is set as the step-out determination prohibition period, the disturbance of the detected waveform at the start-up can be ignored and erroneous step-out determination can be prevented. In the step-out determination prohibition period, since the clock signal is read and the sampling period is automatically changed based on the clock signal, the detected waveform is detected at an appropriate sampling period regardless of the period of the clock signal. It is possible to acquire level data and perform step-out determination with high accuracy.

It is a circuit diagram which shows a stepping motor and a step-out discrimination device. It is a timing chart figure which shows the electricity supply pattern of the exciting coil in a stepping motor. (A) is a waveform diagram showing temperature characteristics of a detected waveform, and (B) is a waveform diagram showing a sampling cycle of level data. It is a flowchart of a step-out determination process.

Explanation of symbols

10 Stepping motors 11 to 14 Excitation coil 20 Drive IC
21 Transistor 30 Oscillator 40 Step-out discrimination device 41 Detection circuit 42 Discrimination unit

Claims (10)

A stepping motor step-out determination device that is step-driven by sequentially energizing a plurality of exciting coils according to a clock signal,
Detection waveform input means for inputting a detection waveform for each step drive from the combined current path of the excitation coil,
Sampling means for sampling the level data of the detected waveform at a predetermined timing starting from the rise or fall of the clock signal;
A difference calculation means for calculating a difference between the level data of the detection waveform input this time and the level data of the detection waveform input previously or before,
A difference comparison means for comparing the absolute value of the calculated difference with a preset step-out determination value;
A step-out determination means for determining that the stepping motor is out of step when the calculated difference exceeds the step-out determination value ;
In the detection waveform input means, based on the energization pattern of the excitation coil, the detection waveform of the synthesized current energized for each input of each clock signal is sequentially input to the sampling means,
The sampling means detects a set of detected waveforms to be compared among the input detected waveforms, samples a plurality of level data at a predetermined sampling period from each of the detected waveforms that form the set, and repeats this. As well as
In the difference calculation means, in order to compare the detection waveforms in the set, the difference between the level data of the detection waveform input this time and the level data of the detection waveform input previously or before is calculated as many times as the number of samplings,
In the difference comparison means, by comparing the step-out determination value that is beforehand set to the sum of the absolute values of a plurality of difference computed, the stepping motor, characterized that you determination by the desynchronization determining means de Key discrimination device. The stepping motor step-out determination apparatus according to claim 1 , wherein the stepping motor is a two-phase stepping motor, and the sampling means samples level data from every other detected waveform. The stepping motor step-out determination device according to claim 1 or 2 , wherein the sampling period and / or the step-out determination value can be changed. Out-discriminating apparatus of a stepping motor according to any one of claims 1 to 3, characterized in that a step-out determination inhibition period the period until a predetermined time has elapsed from the activation of the stepping motor. The stepping motor step-out determination according to any one of claims 1 to 4 , wherein the clock signal is read during the step-out determination prohibition period, and the sampling period is automatically changed based on the clock signal. apparatus. A step-out determination method for a stepping motor that is step-driven by sequentially energizing a plurality of exciting coils according to a clock signal,
The detection waveform of the combined current that is energized every step drive from the combined current path of the exciting coil is sequentially input,
Among the input detection waveforms, detection waveforms to be compared are detected as a set, and a predetermined timing starting from the rising or falling edge of the clock signal at a predetermined sampling period from each detection waveform in the set Sample multiple levels of detected waveform level and repeat this,
In order to compare the detection waveforms in the set, the difference between the level data of the detection waveform input this time and the level data of the detection waveform input previously or before is calculated as many times as the number of samplings ,
Compare the sum of the absolute values of the calculated differences with the preset step-out discrimination value,
A stepping motor step-out determination method, wherein when the calculated difference exceeds a step-out determination value, it is determined that the stepping motor is out of step. The stepping motor step-out determination method according to claim 6, wherein the stepping motor is a two-phase stepping motor, and level data is sampled from every other detected waveform. The stepping motor step-out determination method according to claim 6 or 7, wherein the sampling period and / or the step-out determination value can be changed. Out-determination method of the stepping motor according to claim 6 to 8, characterized in that a step-out determination inhibition period the period until a predetermined time has elapsed from the activation of the stepping motor. The stepping motor step-out determination according to any one of claims 6 to 9 , wherein the clock signal is read during the step-out determination prohibition period, and the sampling period is automatically changed based on the clock signal. Method.