RU2647676C1 - Pulse former from signals of rotation speed induction sensors - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: pulse former from signals of rotation speed induction sensors containing a comparator, a low-pass filter (LPF), an analogue-to-digital converter (ADC) and a central processing unit (CPU), the outputs of the induction sensor are connected to the filter inputs, the filter output is connected to the ADC input and the first input of the comparator, the ADC output is connected to the CPU, and the comparator, ADC and CPU are built-in components of the microcontroller, a reference voltage source, a timer and a pulse generator are additionally introduced, wherein the second output of the LPF is connected to the second input of the comparator, the output of the reference voltage source is connected to the second output of the LPF, the comparator output and the timer output are connected to the CPU inputs, the CPU outputs are connected to the control inputs of the comparator, timer and pulse generator, the generator output is connected to the LPF, and the timer and the pulse generator are built-in components of the microcontroller.

EFFECT: providing high accuracy of measuring the input signal frequency in the presence of various types of interference and simplifying the circuit.

1 dwg

Description

The present invention relates to measuring equipment and can be used in automatic measurement, control and emergency protection systems, which include sensors that generate bipolar signals, in particular induction sensors of speed and flow.

A known device for generating pulses from signals of induction speed sensors [RU patent No. 2459351, C1, H03K 5/153. Pulse generator from signals of induction speed sensors. Published: 08.20.2012], consisting of a low-pass filter, a comparator, a reference signal source, an analog multiplexer.

The disadvantage of this pulse shaper is the lack of diagnostic tools for the condition of the communication line with the speed sensor and the lack of self-monitoring function of the shaper.

Of the known closest in technical essence is a pulse shaper from signals of induction speed sensors [RU patent No. 2458459, C1, Н03К 5/00, G01R 23/02, Shaper of pulses from signals of induction speed sensors. Published: 08/10/2012], consisting of an input low-pass filter, a comparator, two digital-to-analog converters (DACs), an analog-to-digital converter, a central processor, a shunt resistor, and a transistor switch.

The disadvantage of this pulse shaper is the lack of self-control function of the shaper and sufficient complexity.

The present invention is aimed at providing a self-monitoring function, improving the accuracy of measuring the frequency of the input signal in the presence of various kinds of interference and simplifying the shaper circuit.

This goal is achieved by the fact that in the pulse shaper from the signals of induction speed sensors containing a comparator, a low-pass filter (low-pass filter), an analog-to-digital converter (ADC) and a central processor (CPU), and the outputs of the induction sensor are connected to the inputs of the filter, the output the filter is connected to the ADC input, the first input of the comparator, the ADC output is connected to the CPU, and the comparator, ADC and CPU are built-in components of the microcontroller, according to the invention, a reference voltage source is introduced, t timer and pulse generator, the second LPF output connected to the second input of the comparator, the output of the reference voltage source connected to the second LPF output, the comparator output and the timer output connected to the CPU inputs, the CPU outputs connected to the control inputs of the comparator, timer and pulse generator, the generator output connected to the low-pass filter, and the timer and pulse generator are built-in components of the microcontroller.

The reference voltage source introduced into the pulse shaper circuit serves as the first DAC - it shifts the potential at the filter output to the region of positive voltages, but has a simple circuitry: in the typical version, it is built on a resistive voltage divider and capacitor.

Introduced in the pulse shaper circuit timer to set the timing parameters in the implementation of diagnosing operability own (self) and the state of the communication link with the speed sensor: the duration time T _D of diagnosing and diagnosing _CSD period T cycles.

Introduced in the PFN generator circuit included in the job at the time T _A in _the diagnosis cycles that are run by the CPU with a period T _CSD and generator and provides a self-diagnosis link integrity by measuring the output frequency of the generator.

Thus, the proposed combination of features of the invention provides self-control and simplifies the driver circuit.

In FIG. 1 shows a structural diagram of the proposed device pulse shaper from the signals of induction speed sensors. The device consists of an input low-pass filter 1, built on resistors R1-R4 and a capacitor C1, a comparator 2, ADC 3, a central processor 4, a reference voltage source 5, a timer 6, a pulse generator 7. The outputs of the induction sensor are connected to the inputs of the low-pass filter 1. Both outputs of the low-pass filter 1 are connected to the inputs of the comparator 2, the first output of the low-pass filter 1 is connected to the input of the ADC 3, and the second output of the low-pass filter 1 is connected to the output of the reference voltage source 5. The outputs of the comparator 2, the analog-to-digital converter 3, and the timer 6 are connected to the inputs of the CPU 4. The outputs of the CPU 4 connected to the control inputs of the comparator 2 , timer 6 and pulse generator 7. The output of pulse generator 7 is connected to the low-pass filter 1. Comparator 2, ADC 3, central processor 4, timer 6, pulse generator are built-in components of microcontroller 8.

The device operates as follows.

The reference voltage source 5 generates a bias voltage at the second output of the low-pass filter 1, providing at any level of the sensor output signal a positive potential level at the inputs of the ADC 3 and comparator 2. The ADC 3 measures the voltage at the filter output and transmits voltage codes to the CPU 4, which calculates the volt second area S of each half-wave of the input signal and allows the comparator to work only after the condition S> S _{POR is} fulfilled. The threshold value S _{POR is} calculated for each half-wave of the input signal when this signal passes through zero as a predetermined part of the accumulated volt-second area of the whole half-wave. Comparator 2 is triggered when the input signal passes through zero only if the volt-second area of the completed half-wave exceeds the threshold value S _POR . CPU 4 calculates the frequency of the signal from the speed sensor, fixing the arrival time of the output signals from comparator 2 or by counting the number of pulses from comparator 2 during the measurement. The frequency measurement time is determined by timer 6. Thus, the used input signal processing algorithm provides high accuracy of measuring the frequency of the input signal in the presence of various kinds of interference.

The shaper enters the diagnostic mode of its own operability and the state of the communication line with the speed sensor in the case when there is no frequency at the input and the comparator 2 does not work for the time specified by the timer 6. The generator 7 is started in the diagnostic mode and the shaper CPU 4 measures the frequency generator output signal. The conclusion about the integrity of the communication line with the sensor and the health of the driver is made by comparing the measured frequency with the frequency specified by the generator.

Thus, the introduction of a reference voltage source, a timer and a pulse generator into the device allows self-control of the driver, provides high accuracy in measuring the frequency of the input signal in the presence of various kinds of interference and simplifies the driver circuit.

Claims (1)

A pulse generator from signals of induction speed sensors, comprising a comparator, a low-pass filter (LPF), an analog-to-digital converter (ADC) and a central processor (CPU), the outputs of the induction sensor being connected to the inputs of the filter, the output of the filter being connected to the input of the ADC and the first the input of the comparator, the ADC output is connected to the CPU, and the comparator, ADC and CPU are built-in components of the microcontroller, characterized in that the reference voltage source, timer and pulse generator are introduced into it, and the second output An LPF is connected to the second input of the comparator, the output of the reference voltage source is connected to the second output of the LPF, the comparator output and the timer output are connected to the CPU inputs, the CPU outputs are connected to the control inputs of the comparator, timer, and pulse generator, the generator output is connected to the LPF, and the timer and generator pulses are built-in components of the microcontroller.

Images