KR19980054686A - Speed detection method and apparatus in motor - Google Patents

Abstract

Disclosed are a speed detection method and apparatus using an incremental counter in an electric motor. In the present invention, the incremental counter and the counter buffer are used to detect the rotational speed from the amount of change in the count value of the first counter that counts the number of encoder pulses and the amount of change in the count value of the second counter that counts the high clock pulse number. Therefore, the pulsation of the rotational speed is calculated by calculating the rotational speed as close to the instantaneous speed as possible by minimizing the time delay caused by the error between the sampling time occurring at low speed and the actual detection time when the rotational speed is detected using the conventional asynchronous counter. There is an advantage to reduce.

Description

Speed detection method and apparatus in motor

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speed detection method and apparatus in an electric motor, and more particularly, to a speed detection method and apparatus using an incremental counter in a motor using a pulse encoder as a speed detection sensor.

1 is a block diagram of a conventional speed detection apparatus using an asynchronous counter in a motor using a pulse encoder as a position and / or speed detection sensor attached to a DC motor, a permanent magnet synchronous motor, an induction motor, or the like.

In Fig. 1, the microprocessor 11 initially applies the speed detection start signal to the start flip-flop 15. Then, the timer 12 starts to operate in synchronization with the encoder pulse signal. At this time, the first counter 13 that counts the high (H) clock pulse and the second counter 14 that counts the encoder pulse start counting. Next, as shown in FIG. 2, when the encoder pulse occurs for the first time after the sampling time Ts, the stop flip-flop 16 operates to apply an interrupt to the microprocessor 11 and simultaneously with the first counter 13. The second counter 14 is stopped. Next, as shown in FIG. 4, the count values of the first counter 13 and the second counter 14 are read (steps 41 and 42), and the speed of the motor is calculated as in Equation 1 below (step 43). step). Thereafter, after the first and second counters 13 and 14 are reset, the next measurement is started (step 44).

[Equation 1]

In Equation 1, Nr is the average rotational speed of the motor in units of rpm (rotation per minutes), H is the clock frequency, M is the number of encoder pulses counted by the second counter 14, R is a pulse type encoder ( The number of response pulses per revolution (T), not shown, represents the number of high clock pulses counted by the first counter 13, respectively. That is, in step 43, K is a constant corresponding to (60 * H / R).

However, the above-described speed detection method can be implemented only by the interrupt method. In addition, the asynchronous speed detection method has the following disadvantages at low speed. Since the first counter 13 is counted up to the first encoder pulse after the sampling time Ts, the difference between the actual detection time Td and the sampling time Ts Becomes large. Also, Is not reset after one sampling time and continues to accumulate. Therefore, the difference between detection time and sampling time ( ) Gets bigger and bigger. Meanwhile, Is fluctuated together with the variation of the rotational speed of the motor, resulting in pulsation of the motor.

In addition, the first counter 13 and the second counter 14 must be reset after reading the count value. If the length of the first counter 13 will cause an overflow. Therefore, in order to prevent this overflow, since a counter with a large capacity must be selected as the first counter 13, a burden occurs on the hardware.

Accordingly, an object of the present invention is to use the change amount of the count value of the first counter counting the number of encoder pulses using the incremental counter and the counter buffer in the motor and the change amount of the count value of the second counter counting the high clock pulse count The present invention provides a method for detecting a rotation speed.

Another object of the present invention is to provide an apparatus most suitable for realizing the speed detecting method in an electric motor.

In order to achieve the above object, the speed detection method according to the present invention is a motor using a pulse type encoder as a position and / or speed detection sensor attached to an electric motor or the like, wherein (a) an encoder pulse is input from the pulse type encoder. Temporarily storing a count value of the encoder pulse each time; (b) temporarily storing a count value of a high clock pulse each time an encoder pulse is input from the pulse type encoder; (c) reading the count value of the encoder pulse stored in the step (a) and the count value of the high clock pulse stored in the step (b) every sampling time; (d) calculating a change amount of the count value of the encoder pulse and a change amount of the count value of the high clock pulse with respect to a current sampling time and a previous sampling time; And (e) calculating a rotational speed of the motor from the change amount of the count value of the encoder pulse and the change amount of the count value of the high clock pulse.

In order to achieve the above object, the speed detecting device according to the present invention is an incremental counter for counting the number of pulses of the pulsed encoder in a motor using a pulse encoder as a position and / or speed detection sensor attached to an electric motor or the like. Phosphorus first counter; A first counter buffer temporarily storing a count value of the first counter each time a pulse of the encoder is input; A second counter, which is an incremental counter that counts a high number of clock pulses; A second counter buffer temporarily storing the count value of the second counter whenever the pulse of the encoder is input; And rotation of the motor from a change amount of the count value of the encoder pulse number read from the first counter buffer and a change amount of the count value of the high clock pulse number read from the second counter buffer for a predetermined sampling time. And a microprocessor for detecting the speed.

1 is a block diagram of a conventional speed detection apparatus using an asynchronous counter in an electric motor;

2 is a detailed timing diagram of the speed detection device shown in FIG. 1;

3 is an enlarged timing diagram of the detailed timing diagram shown in FIG. 2;

4 is a flowchart of a conventional speed detection method using an asynchronous counter in an electric motor;

Fig. 5 is a block diagram showing the configuration of a speed detecting device according to the present invention using an incremental counter in an electric motor.

6 is a detailed timing diagram of the speed detection device shown in FIG. 5;

7 is an enlarged timing diagram of the detailed timing diagram shown in FIG. 6;

8 is a flowchart of a speed detection method according to the present invention using an incremental counter in an electric motor.

* Explanation of symbols for main parts of the drawings

51 ... microprocessor 52 ... synchronizer

53,55 ... counter 54,56 ... counter buffer

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Fig. 5 is a block diagram of a speed detection device according to the present invention using an incremental counter in an electric motor, in which a first counter 53 and a first counter 53 are incremental counters that count pulses of a pulse encoder (not shown). The first counter buffer 54 temporarily storing the count value of the counter 53, the second counter 55 and the second counter 53 which are incremental counters for counting the number of high clock pulses are temporarily stored. The number of changes in the count value of the first counter and the number of high clock pulses that count the number of encoder pulses read from the second counter buffer 56, the first counter buffer 54, and the second counter buffer 56 are stored. And a microprocessor 51 for detecting the rotational speed from the amount of change in the count value of the second counter.

FIG. 6 is a detailed timing diagram of the speed detector shown in FIG. 5, and FIG. 7 is an enlarged timing diagram of the detailed timing diagram shown in FIG. 6. Here, Ts represents a sampling time and Td represents a speed detection time, respectively.

8 is a flowchart of a speed detection method according to the present invention using an incremental counter in an electric motor, which is performed by the microprocessor 51 of FIG.

Next, the operation of the present invention will be described with reference to FIGS. 5 to 8.

First, the first counter 53, which is an incremental counter that counts the number of pulses of a pulsed encoder (not shown), and the second counter 55, which is an incremental counter that counts the number of high clock pulses, includes a speed detection start signal, It is an incremental counter that counts an infinite number of allowable bits of the counter without requiring a stop signal and a reset signal. The operation process is as follows.

Each time an encoder pulse is input from a pulsed encoder (not shown), the count value of the first counter 53 and the count value of the second counter 55 are respectively counted by the first counter buffer 54 and the second counter buffer ( 56).

Then, the microprocessor 51 reads the count values written in the first counter buffer 54 and the second counter buffer 56 at each sampling time (steps 81 and 82).

The microprocessor 51 counts the counts of the first counter 53 and the second counter 55 read in steps 81 and 82, and the first counter 53 and the second counter 55 read immediately before. Difference in the count value , ) Are obtained as shown in Equation 2 below.

[Equation 2]

Obtained by Equation 2 , The average rotational speed Nr is calculated using Equation 3 below (step 83).

[Equation 3]

In Equation 3, Is a difference between the count value of the first counter 53 currently read and the count value of the first counter 53 just read. Denotes a difference between the count value of the second counter 55 currently read and the count value of the second counter 55 immediately read. K corresponds to (60 * H / R) in Equation 1 as well.

The speed detection method as described above is not limited to the calculation time of the microprocessor because the microprocessor 51 only needs to read the count values of the first counter 53 and the second counter 55 at a desired time. In addition, the speed detection method using the conventional asynchronous counter There is no accumulation of and no overflow occurs.

As described above, in the motor, according to the speed detecting method and apparatus according to the present invention, the change amount of the count value of the first counter and the high clock pulse number are counted by using the incremental counter and the counter buffer. The rotational speed is detected from the change amount of the count value of the second counter. Therefore, the pulsation of the rotational speed is calculated by calculating the rotational speed as close to the instantaneous speed as possible by minimizing the time delay caused by the error between the sampling time occurring at low speed and the actual detection time when the rotational speed is detected using the conventional asynchronous counter. There is an advantage to reduce.

In addition, since the speed detection start signal, the stop signal, the counter reset signal, and the like, which are conventionally used, are not limited to the capacity of the second counter, the burden of hardware is reduced. In addition, it is possible to reduce the time burden of the microprocessor for calculating the rotation speed and to prevent the overflow of the second counter that may occur during the low speed rotation.

Claims (3)

In a motor using a pulse encoder as a position and / or speed detection sensor attached to the motor, etc., (a) temporarily storing a count value of the encoder pulse each time an encoder pulse is input from the pulse type encoder; (b) temporarily storing a count value of a high clock pulse each time an encoder pulse is input from the pulse type encoder; (c) reading the count value of the encoder pulse stored in the step (a) and the count value of the high clock pulse stored in the step (b) every sampling time; (d) calculating a change amount of the count value of the encoder pulse and a change amount of the count value of the high clock pulse with respect to a current sampling time and a previous sampling time; And (e) calculating the rotational speed of the motor from the change amount of the count value of the encoder pulse and the change amount of the count value of the high clock pulse. In a motor using a pulse encoder as a position and / or speed detection sensor attached to the motor, etc., A first counter for counting the number of pulses of the pulsed encoder; A first counter buffer temporarily storing a count value of the first counter each time a pulse of the encoder is input; A second counter for counting a high number of clock pulses; A second counter buffer temporarily storing the count value of the second counter whenever the pulse of the encoder is input; And The rotational speed of the motor from the change amount of the count value of the encoder pulse number read from the first counter buffer and the change amount of the count value of the high clock pulse number read from the second counter buffer for a predetermined sampling time. Speed detection apparatus for an electric motor comprising a microprocessor for detecting the. 3. The speed detecting apparatus of claim 2, wherein the first and second counters are incremental counters.