CN102628697A - Method for dynamic memory of physical quantity and system thereof - Google Patents

Abstract

A physical quantity dynamic memory method and system, the method is: when detecting a certain physical quantity in a measurement and control system, the indirect physical quantity reflecting the physical quantity can be detected, and then the detected indirect physical quantity can be converted into a measured physical quantity, so as to realize the physical quantity The detection of the measured physical quantity is converted into a voltage signal and stored in the memory circuit, and its size changes in real time according to the size and change law of the measured physical quantity, so as to realize dynamic memory; the signal acquisition circuit in the system passes through the sensor Acquisition of indirect physical quantities; A/D conversion of the indirect physical quantities by the single-chip microcomputer, and output in the form of PWM waves; LPF circuit smoothes and filters the PWM waves; the memory circuit performs dynamic memory of physical quantities according to the output voltage of the LPF circuit; the output circuit is used for memory circuits. The output signal is buffered and output; the reset circuit resets the memory circuit; the conversion algorithm converts the indirect physical quantity into the measured physical quantity, and then converts it into a PWM wave output.

Description

Method and system for dynamic memory of physical quantity

technical field

The invention relates to the detection and dynamic memory of physical quantities in a measurement and control system.

Background technique

When performing physical quantity detection in some measurement and control systems, sometimes we encounter such a situation: because some physical quantities cannot be directly detected, it is necessary to detect some specific indirect physical quantities, and then the measured indirect physical quantities are realized through certain conversions. The detection of the measured physical quantity, and when these indirect physical quantities disappear for some reason, or the detection device is also powered off for some reason when the indirect physical quantity disappears, it is required that the detection device can promptly detect the corresponding measured physical quantity before the indirect physical quantity disappears. Since these physical quantities are often attenuated according to a certain law, it is required that the amount of memory should also be attenuated according to the same law, that is, dynamic memory. For example, in the digital control system of the motor, the thermal capacity is an important control basis, but the thermal capacity cannot be directly detected, and the thermal capacity value needs to be obtained by detecting the current, and when the motor is powered off, or the motor and the detection circuit are powered off at the same time The heat capacity value can be dynamically memorized (the heat capacity of the motor decays dynamically with time after power-off), so that the controller can control the motor reasonably according to the heat capacity value before power-off when the motor and detection circuit are powered on next time.

Contents of the invention

The object of the present invention is to provide a physical quantity dynamic memory method and system.

The present invention is a physical quantity dynamic memory method and system, the method comprising:

(1) When detecting a certain physical quantity in the measurement and control system, if the physical quantity cannot be obtained directly, the detection of the physical quantity can be realized by detecting the indirect physical quantity reflecting the physical quantity, and then converting the detected indirect physical quantity into the measured physical quantity;

(2) Convert the obtained measured physical quantity into a voltage signal and store it in the memory circuit. The voltage signal changes in real time according to the measured physical quantity and its changing law, so as to realize the dynamic memory of the physical quantity that cannot be directly obtained.

Realize the system of above-mentioned physical quantity dynamic memory method, this system is used for the signal acquisition circuit 1 of signal acquisition, is used for carrying out the single-chip microcomputer 2 of algorithm realization and control, is used for the LPF that the PWM wave that single-chip microcomputer 2 outputs carries out low-pass filtering Circuit 3, memory circuit 4 for realizing dynamic memory of physical quantity, output circuit 5 for buffering output signal, reset circuit 6 for reset control of memory circuit 4, conversion for converting physical quantity into PWM wave Algorithm 7 is composed. Among them, the signal acquisition circuit 1 collects the indirect physical quantity through the sensor, and adjusts the collected indirect physical quantity signal; the single-chip microcomputer 2 (contains an A/D converter) is used to perform A/D conversion on the collected indirect physical quantity to obtain the indirect physical quantity According to the digital signal, the indirect physical quantity is converted into the measured physical quantity that needs to be memorized through the relevant algorithm, and it is output in the form of PWM wave; another function of the single-chip microcomputer 2 is to reset the memory circuit; The output PWM wave is smoothed and filtered; the memory circuit 4 carries out physical quantity dynamic memory according to the output voltage of the LPF circuit 3; the output circuit 5 is used to buffer and output the output signal of the memory circuit 4; the reset circuit 6 is used to control the The memory circuit 4 performs a reset operation to obtain a definite initial state of the memory circuit; the conversion algorithm 7 is used to convert the indirect physical quantity into a measured physical quantity, and then convert it into a PWM wave output.

In the system realized by the present invention, the output signal is the measured physical quantity that needs to be memorized, and is output in the form of voltage, and its size depends on the indirect physical quantity input to the A/D converter 2-1 contained in the single-chip microcomputer 2. The measured physical quantity The size of the indirect physical quantity follows the change of the indirect physical quantity in real time, and the output voltage of the output circuit also changes in real time with the change of the indirect physical quantity. When the indirect physical quantity disappears for some reason, or when the indirect physical quantity and the power supply of the detection circuit disappear at the same time, the memory circuit 4 in the method and implemented system provided by the present invention can store the corresponding measured physical quantity at the moment before the indirect physical quantity disappears. Memorize it and output it in the form of voltage. If the measured physical quantity memorized at this time is dynamically changing (such as decaying with time according to a certain rule), the memory circuit provided in the present invention can make its output voltage also dynamically change in real time according to the size and changing law of the measured physical quantity, so as to This realizes the dynamic memory of the physical quantity.

Description of drawings

Fig. 1 is a schematic diagram of the overall structure of the present invention, and Fig. 2 is a schematic diagram of the process of realizing PWM waves by a single-chip microcomputer.

Detailed ways

The present invention is a physical quantity dynamic memory method and system, the method comprising:

(1) When detecting a certain physical quantity in the measurement and control system, if the physical quantity cannot be obtained directly, the detection of the physical quantity can be realized by detecting the indirect physical quantity reflecting the physical quantity, and then converting the detected indirect physical quantity into the measured physical quantity;

(2) Convert the obtained measured physical quantity into a voltage signal and store it in the memory circuit. The voltage signal changes in real time according to the measured physical quantity and its changing law, so as to realize the dynamic memory of the physical quantity that cannot be directly obtained.

As shown in Figure 1, realize the system of above-mentioned physical quantity dynamic memory method, this system is used for the signal acquisition circuit 1 of signal acquisition, is used for carrying out the single-chip microcomputer 2 of algorithm realization and control, is used for the PWM wave that single-chip microcomputer 2 outputs LPF circuit 3 for low-pass filtering, memory circuit 4 for realizing dynamic memory of physical quantities, output circuit 5 for buffering output signals, reset circuit 6 for reset control of memory circuit 4, and memory circuit 6 for storing physical quantities The conversion algorithm for converting to PWM wave consists of 7. Among them, the signal acquisition circuit 1 collects the indirect physical quantity through the sensor, and adjusts the collected indirect physical quantity signal; the single-chip microcomputer 2 (contains an A/D converter) is used to perform A/D conversion on the collected indirect physical quantity to obtain the indirect physical quantity According to the digital signal, the indirect physical quantity is converted into the measured physical quantity that needs to be memorized through the relevant algorithm, and it is output in the form of PWM wave; another function of the single-chip microcomputer 2 is to reset the memory circuit; The output PWM wave is smoothed and filtered; the memory circuit 4 carries out physical quantity dynamic memory according to the output voltage of the LPF circuit 3; the output circuit 5 is used to buffer and output the output signal of the memory circuit 4; the reset circuit 6 is used to control the The memory circuit 4 performs a reset operation to obtain a definite initial state of the memory circuit; the conversion algorithm 7 is used to convert the indirect physical quantity into a measured physical quantity, and then convert it into a PWM wave output.

The whole system works as follows:

In the signal acquisition circuit, the indirect physical quantity is collected through the sensor, and the collected signal is conditioned, including amplification and filtering; the A/D converter included in the single-chip microcomputer is used to perform analog/digital conversion on the collected signal to obtain the indirect physical quantity The digital signal of the conversion result is digitally filtered to improve the accuracy of the data, and then the measured physical quantity is obtained from the indirect physical quantity through a certain conversion relationship in the single-chip microcomputer, and the measured physical quantity obtained is converted into a PWM wave output through the conversion algorithm , using the duty cycle of the PWM wave to reflect the size of the measured physical quantity; the output PWM wave is filtered by a low-pass filter to control the memory circuit, and the measured physical quantity is dynamically memorized in the memory circuit through the voltage change of the memory circuit, and the memory The output of the circuit changes dynamically with time, so as to simulate the real-time changes of the measured physical quantity.

The conversion algorithm 7 that converts the indirect physical quantity into the measured physical quantity and converts it into PWM wave output is realized by the following steps: the first step is to determine the relationship between the measured physical quantity and the indirect physical quantity, and convert the indirect physical quantity into the measured physical quantity. Measure the physical quantity (the specific relationship between the measured physical quantity and the indirect physical quantity varies with the actual system); the second step is to determine the variation range of the measured physical quantity according to the specific conditions of the actual system, and record its maximum value as 1, The corresponding PWM wave duty cycle is 100%; the third step is to divide the measured physical quantity at a certain moment obtained by the measurement by the maximum value of the measured physical quantity, and use the result (its size is between 0-1) as PWM wave duty cycle, then its duty cycle is a certain value between 0-100%; the fourth step is to output PWM wave with this duty cycle. The above algorithm is realized in the single-chip microcomputer through the program.

The memory circuit is reset through the reset circuit controlled by the single chip microcomputer, so as to obtain the initial state of the memory circuit with zero voltage. In the normal detection state, the memory circuit is periodically refreshed by the single-chip microcomputer with the PWM wave, so that the storage voltage of the memory circuit changes dynamically with the duty cycle of the PWM wave, so as to represent the real-time change of the measured physical quantity, and the refresh frequency is based on The characteristics and requirements of the signal under test are controlled by the single-chip microcomputer. Generally, at least the refresh frequency must be guaranteed not to be less than twice the upper limit cut-off frequency of the signal under test. When the indirect physical quantity disappears due to some reason, or the indirect physical quantity and the power supply of the detection circuit disappear at the same time, the storage element in the memory circuit can memorize the measured physical quantity corresponding to the moment before the indirect physical quantity disappears in the form of voltage on the memory element. , and the voltage on the memory element can dynamically change in real time according to the size and change law of the measured physical quantity.

In the method provided by the present invention, the indirect physical quantity can be selected according to the specific application occasion; by rationally designing the circuit structure of the memory circuit and properly selecting the circuit parameters, the memory characteristics of the circuit can be consistent with the changing laws of different measured physical quantities, thereby satisfying The requirement of the dynamic memory of the measured physical quantity. When choosing a single-chip microcomputer, it is necessary to choose a single-chip microcomputer with an A/D converter, and its A/D converter must have sufficient resolution. At the same time, for the convenience of programming, the single-chip microcomputer must contain a PWM module.

When the method provided by the invention is applied to the dynamic memory of a certain physical quantity, the maximum error is not more than 10%, a satisfactory effect is obtained, and the engineering requirement is met. If the accuracy of the circuit parameters is improved and the control algorithm is optimized at the same time, the memory error can be further reduced.

Claims (4)

1. A kind of method for carrying out dynamic memory to physical quantity, its step is: (1) When detecting a certain physical quantity in the measurement and control system, if the physical quantity cannot be obtained directly, the detection of the physical quantity can be realized by detecting the indirect physical quantity reflecting the physical quantity, and then converting the detected indirect physical quantity into the measured physical quantity; (2) Convert the obtained measured physical quantity into a voltage signal and store it in the memory circuit. The voltage signal changes in real time according to the measured physical quantity and its changing law, so as to realize the dynamic memory of the physical quantity that cannot be directly obtained. 2. realize the system of the described physical quantity dynamic memory method of claim 1, it is characterized in that this system is by the signal acquisition circuit (1) that is used for signal acquisition, the single-chip microcomputer (2) that is used to carry out algorithm realization and control, is used for single-chip microcomputer (2) The LPF circuit (3) for performing low-pass filtering on the output PWM wave, the memory circuit (4) for realizing the dynamic memory of physical quantities, the output circuit (5) for buffering the output signal, and the memory circuit for (4) A reset circuit (6) for reset control and a conversion algorithm (7) for converting the physical quantity into a PWM wave are composed; wherein the signal acquisition circuit (1) collects the indirect physical quantity through the sensor, and collects the indirect physical quantity signal Carry out recuperation; The one-chip computer (2) is used for carrying out A/D conversion to the indirect physical quantity that gathers, obtains the digital signal of indirect physical quantity, accordingly converts the indirect physical quantity into the measured physical quantity that needs to be memorized by relevant algorithm, and it is with PWM Another function of the single-chip microcomputer (2) is to reset the memory circuit; the LPF circuit (3) smoothes and filters the PWM wave output by the single-chip microcomputer (2); the memory circuit (4) is based on the LPF circuit (3) The output voltage is dynamically memorized as a physical quantity; the output circuit (5) is used to buffer and output the output signal of the memory circuit (4); the reset circuit (6) is used to perform a reset operation on the memory circuit (4) under the control of a single-chip microcomputer to A definite initial state of the memory circuit is obtained; the conversion algorithm (7) is used to convert the indirect physical quantity into the measured physical quantity, and then convert it into PWM wave output. 3. according to the system described in claim 2 realizing the physical quantity dynamic memory method described in claim 1, it is characterized in that the single-chip microcomputer (2) first obtains the measured physical quantity by conversion relationship according to the indirect physical quantity obtained, and then by algorithm and program, The measured physical quantity is converted into a PWM wave output in real time, wherein the duty ratio of the PWM wave is proportional to the measured physical quantity; the single-chip microcomputer (2) regularly uses the PWM wave whose duty ratio changes in real time according to a fixed frequency to the voltage signal stored in the memory circuit Perform a refresh operation, and the frequency of the refresh operation is not less than twice the upper limit cut-off frequency of the measured signal. 4. according to the system described in claim 2 realizing the physical quantity dynamic memory method described in claim 1, it is characterized in that the voltage size of the memory circuit (4) output is controlled by the duty ratio of the PWM wave output by the single-chip microcomputer (2), Moreover, when the indirect physical quantity disappears for some reason, or the detection circuit also loses power when the indirect physical quantity disappears, the voltage stored in the memory circuit can change in real time according to the size and change law of the measured physical quantity, so as to represent the dynamics of the physical quantity that needs to be memorized change; the structure and circuit parameters of the memory circuit (4) depend on the dynamic change law of the measured physical quantity, and the memory effect meeting the requirements shall prevail.

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