JPH0486570A - Detection of peak point for ac signal - Google Patents

Abstract

PURPOSE:To achieve shorter processing time for detection by having a period during which an AC signal coincides with respective analog values rising (falling) or falling (rising) to detect a maximum (minimum) point of the AC signal. CONSTITUTION:When a specified bit of digital value is preset on a register 2 through an internal bus 1, the value is converted to an analog value (threshold) with a D/A converter 3. A comparator 4 compares an AC signal S with the threshold and an output signal thereof 4 is transferred to the bus 1. First, when the signal S coincides with the threshold rising at the time Ta, the output signal of the comparator 4 rises from 1 to 0 to be transferred to the bus 1 and the operation of an internal timer is started. Thereafter, at the time Tb, as the signal S coincides with the threshold falling, the output signal of the comparator 4 rises from 0 to 1 to be transferred to the bus 1 again and the operation of the internal timer is ended. Then, the period (Tb-T>=a) is halved to detect a maximum point Vmax of the signal S.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a method for detecting a peak point of an alternating current signal.

(b) Prior Art Conventionally, in a microcomputer, when detecting the maximum or minimum point of an AC signal, a sampling point of the AC signal is compared with a threshold (changeable).

That is, the maximum point of the AC signal is detected when all the sampling points of the AC signal are smaller than the threshold, and the minimum point of the AC signal is detected when all the sampling points of the AC signal are smaller than the threshold. Ta.

(c) Problems to be Solved by the Invention However, since the threshold value must be changed for each sampling point of the AC signal, the number of processing times of the program to detect the maximum or minimum point of the AC signal increases. However, there is a problem in that the processing time required to detect the maximum or minimum point of the AC signal becomes long.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a method for detecting a peak point of an AC signal, which can shorten the processing time for detecting the maximum point or minimum point of an AC signal.

(d) Means for Solving the Problems The present invention has been made to solve the above-mentioned problems, and firstly, it provides a register in which a digital value of a predetermined bit is preset, and a register in which a digital value of a predetermined bit is preset. a DA converter that converts a digital value into an analog value; and a comparator that compares the analog value converted by the DA converter with a predetermined AC signal, and the AC signal increases and matches the analog value. Then, when the AC signal falls and matches the analog value, the timer operation is started based on the output signal of the comparator, and the timer operation is started based on the output signal of the comparator. The present invention is characterized in that the maximum point of the AC signal is detected by halving the period from the start to the end of the operation. Secondly,
A register in which a digital value of a predetermined bit is preset, a DA converter that converts the digital value preset in the register into an analog value, and a comparator that compares the analog value converted by the DA converter with a predetermined AC signal. and when the AC signal matches the analog value while falling, a timer operation is started based on the output signal of the comparator, and thereafter, when the AC signal matches the analog value while rising. ,
The present invention is characterized in that the minimum point of the AC signal is detected by terminating the timer operation based on the output signal of the comparator and halving the period from when the timer operation is started to when it is terminated.

(E) Effect According to the present invention, when the AC signal increases and matches the analog value, a timer operation is started based on the output signal of the comparator, and then, when the AC signal decreases and matches the analog value, The maximum point of the AC signal can be detected by terminating the timer operation based on the output signal of the controller and halving the period from the start to the end of the timer operation. Similarly, when the AC signal is falling and matches the analog value, the timer operation is started based on the output signal of the comparator, and then when the AC signal is rising and matches the analog value, the timer operation is started based on the output signal of the comparator. The minimum point of the AC signal can be detected by terminating the timer operation and halving the period from the start to the end of the timer operation.

(f) Example The details of the present invention will be specifically explained with reference to the drawings.

FIG. 1 is a block diagram of essential parts of a microcomputer for implementing the present invention, and FIG. 2 is a waveform diagram for explaining the present invention.

In Figure 1, the digital value of a predetermined bit is transferred to an internal bus (
1), the digital value of the predetermined bit is converted into an analog value (hereinafter referred to as threshold value) by the DA converter (3), and the alternating current signal S
and the threshold value are compared by a comparator (4), and the output signal of the comparator (4) is transferred to the internal bus (1).

First, the maximum point of the AC signal S. At time 0 T, when the AC signal S rises and matches the threshold value, the output signal of the comparator (4) falls from "1" to "0" and is transferred to the internal bus (1). Therefore, the operation of an internal timer (not shown) is started. Thereafter, at time Tb, when the AC signal S falls and matches the threshold value, the output signal of the comparator (4) rises from "0" to "1" and the internal bus (1)
Since the data is transferred again to , the operation of the internal timer is terminated. Then, the period (T b - T ) from when the operation of the internal timer starts to when it ends is halved, and the maximum points 1 and 8 of the AC signal S are detected.

Next, a case will be described in which the minimum point V m I n of the AC signal S is detected. At time T, when the AC signal S falls and matches the threshold value, the output signal of the comparator (4) rises from "0" to "1" and the internal bus (
1), the internal timer starts operating. After that, at time Tc, when the AC signal S increases and matches the threshold value, the output signal of the comparator (4) falls from "1" to "0" and is transferred again to the internal bus (the internal bus), so the internal timer operation is terminated. Then, when the period (T e - T b) from the start to the end of the operation of the internal timer is 1/2, the minimum point 2, 1 degree of the AC signal S is detected.

As described above, since the method compares the AC signal with one predetermined threshold value, the number of processing times of the program for detecting the maximum and minimum points of the AC signal is reduced, and the maximum and minimum points of the AC signal can be detected. This means that the processing time for pressing is reduced.

(G) Effects of the Invention According to the present invention, since the method compares an AC signal with one predetermined threshold value, it is possible to reduce the number of processing times of a program for detecting the maximum and minimum points of an AC signal. The advantage is that the processing time for detecting the maximum and minimum points of can be shortened.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of essential parts of a microcomputer for implementing the present invention, and FIG. 2 is a waveform diagram for explaining the present invention. (2) Register (3) (4) Comparator. DA Compa Figure 1

Claims (2)

[Claims] (1) A register in which a digital value of a predetermined bit is preset, a DA converter that converts the digital value preset in the register into an analog value, and a DA converter that converts the analog value converted by the DA converter and a predetermined AC signal. and a comparator for comparison, and when the AC signal increases and matches the analog value, a timer operation is started based on the output signal of the comparator, and then the AC signal matches the analog value while decreasing. When they match, the timer operation is terminated based on the output signal of the comparator, and the period from the start to the end of the timer operation is halved, thereby detecting the maximum point of the AC signal. A method for detecting the peak point of an AC signal. (2) A register in which a digital value of a predetermined bit is preset, a DA converter that converts the digital value preset in the register into an analog value, and a DA converter that converts the analog value converted by the DA converter and a predetermined AC signal. and a comparator for comparison, when the AC signal matches the analog value while falling, a timer operation is started based on the output signal of the comparator, and thereafter, the AC signal matches the analog value while rising. When they match, the timer operation is terminated based on the output signal of the comparator, and the minimum point of the AC signal is detected by halving the period from when the timer operation starts to when it ends. A method for detecting the peak point of an AC signal.