SU1695411A1 - Device for checking time of response of electromagnetic mechanism - Google Patents

Abstract

The invention relates to an instrumentation technique and can be used in devices for measuring the response time of an electromagnetic drive operating in a pulsed mode with saturation of a magnetic circuit and not having its own contacts. The purpose of the invention is to improve the accuracy, noise immunity and simplify control of the response time of the electromagnetic mechanism. The device comprises a meter, first and second transistors, a current sensor, first and second comparison circuits, a differential amplifier, analog and digital delay lines, and a trigger. New in the proposed device is the presence of the first and second comparison circuits, a differential amplifier, analog and digital delay lines and a trigger. 4 il.

Description

The invention relates to an instrumentation technique and can be used in devices for measuring the response time of an electromagnetic drive operating in a pulsed mode with saturation of a magnetic circuit and not having its own contacts.

A device is known for controlling the response time of an electromagnetic mechanism, comprising a differentiating transformer included in the power supply circuit of the electromagnetic mechanism (EMM), a reference device, a differentiating circuit, an anti-coincidence circuit connected through a differentiating circuit to the secondary winding of the differentiating transformer to which the waiting multivibrator signal input is connected, the output which is connected to the second input of the anti-matching circuit, and the output of the latter is connected to the reference device.

The disadvantage of such a device is the limited noise immunity and, as a result, insufficient accuracy of measurement of the response time interval.

Closest to the present invention is a device for controlling the response time of an electromagnetic mechanism containing a meter, the first and second transistors, the emitters of which are combined with one of the poles of the power source, and the bases are connected to the outputs of the paraphase signal sources, and the collector of the first transistor through the first control winding connected to the other pole of the power source, which through a series-connected second control winding and a resistive current form sensor is combined with a collector the second transistor and the first inputs of the adder, the indicator, as well as through a switch with the first input of the first and the output of the second pulse generator, with

cl

with

ON Y SL

N

This output of the second pulse generator is connected via an adjustable resistor to another pole of the power source and the corresponding inputs of the meter and adder, the output connected to the third input of the indicator, the second input of which is connected to the connection point of the resistive current waveform sensor and the second winding of the EMM control.

A disadvantage of this device is the low measurement accuracy, i.e. the trigger time of the EMM is determined visually by the operator, based on the indicator readings. At the same time, the accuracy of measurement determines the resolution of the indicator, as well as the subjective factor contributed by the operator involved in the measurement process.

The purpose of the invention is to improve the accuracy of noise immunity and simplify control of the response time of the EMM.

This goal is achieved due to the fact that the device for monitoring the response time of an EMM containing a resistive current waveform sensor, a meter, first and second transistors, the emitters of which are connected to the bus of one of the poles of the power source, are connected to the outputs of the paraphase sources signals, the collector of the first transistor is connected to the bus of the other pole of the power source through the control winding, and the collector of the second transistor is connected to the same bus through a series-connected resistive sensor of the forms current and a second EMM control winding, a differential amplifier, the first and second comparison circuit, analog and digital delay circuits are triggered, the inputs of the differential amplifier are connected in parallel to the current form sensor, the output is to the first inputs of both comparison circuits and analog circuit delay, the output connected to the second input of the second comparison circuit, the output of which through the digital delay circuit is connected to the clock input of the trigger, the output connected to the meter, and the setting R input to the output This is the first comparison circuit, the second input of which is combined with the common bus of the device.

Figure 1 presents the functional diagram of the proposed device; 2 and 3 illustrate possible embodiments of digital and analog delay circuits; figure 4 - diagrams of the device.

The device for controlling the response time of the EMM consists of the first 1 and second 2 switching transistors, conclusions 3 for connecting the first winding

control EMM, pin 4 to connect the second winding control EMM, resistive sensor 5 current form, differential amplifier 6, the first 7 and second 9 comparison circuits, analog 8 and digital 10 delay circuits, trigger 11 and meter 12 time interval.

The first control winding EMM is connected to the power supply bus and the collector of the first 1 transistor, the second control winding connects to the mentioned power supply bus and is connected to the collector of the second transistor 2 via a current waveform sensor 5. The bases of transistors 1 and 2 are connected to control signal sources. The outputs of the sensor 5 of the current form are connected to the inputs of the differential amplifier 6. The output of the differential amplifier 6 is connected via the first comparison circuit 7 to the R input of the trigger 11. The clock input of the trigger 11 is connected in series through the analog delay circuit 8, the second comparison circuit 9 and the digital delay circuit 10c the output of the amplifier 6. The output of the trigger 11 is connected to the input of the meter 12 time intervals.

Differential amplifier 6 can be performed, for example, by a known scheme. Circuits 7 and 10 comparisons can be performed on serial chips of the type 521 SAZ.

Analog delay circuit 8 can be performed, for example, according to the scheme shown in FIG. 3, where DD1 is a KTZ chip 564, DD2 is a LN2 chip 564.

Digital delay circuit can be performed, for example, according to the scheme shown in figure 2, where DD1 - chip 564 LN2, trigger 11-564 TM2. Resistive sensor 5 forms of current can be implemented on the resistor C5-14V-1VT-2 Ohm ± 2%.

The meter 12 is a frequency meter of type 43-33, operating in the mode of measuring the duration.

The device works as follows.

After applying signals to the bases of transistors 1 and 2 as a sequence of para-phase pulses (Fig. 4a), the EMM begins to flow through the winding (for example, the second), which is further converted by a resistive sensor 5 of the current form and the differential amplifier 6 into the voltage proportional to the magnitude of the current (figb). As can be seen from the diagram, at the leading edge of a voltage pulse proportional to the current of the coil, there is a characteristic section (point 3), due to the operating mode of the drive with the saturation of the magnetic circuit and the corresponding

time of the end of the movement of the core, which is subject to control. When a current appears in the EMM winding, a signal is generated at the output of the comparison circuit 7, allowing the operation of the counting trigger 11 at the Reset input (Fig. 4c). In the comparison circuit 9, the signal from the current waveform sensor is compared to the signal from the same sensor, but delayed by the analog delay circuit 8. At this moment, the sign of the increment of the function of the current waveform is determined. When the magnitude of the signal at its second input (section 1-2 and 3-4 of fig.4b), two positive pulses are formed at the output of this circuit (fig.4g). The leading edge of the first pulse corresponds to the instant of current occurrence in the EMM winding (the moment when the EMM core starts to move). The leading edge of the second pulse corresponds to the instant of stopping of the EMM core. The leading edge of the first pulse from the comparison circuit 9, passed through the digital delay circuit 10, the trigger 11 is set to one, the leading edge of the second pulse returns to the initial state (Fig. 4e), completing the process of forming the time interval whose duration corresponds to the time triggered EMM. A digital delay circuit is necessary to eliminate the undefined state of a trigger while simultaneously receiving a signal at both inputs of a trigger. The duration of the time interval formed by the trigger 11. is measured using a time interval meter 12.

After the removal of the control signal, the comparison circuit 7 returns to the initial state and prohibits the operation of the trigger 11. After the next control pulse is applied, the process will be repeated.

In this case, the accuracy of determining the response time of the EMM is determined by the delay time of the signal from the current form sensor, which is selected by several orders of magnitude less than the response time of the EMM and on the value of which the destabilizing factors have little effect.

The accuracy of the measurement time of the prototype is determined by the resolution of the cathode ray tube indicator. Thus, in the case of using the oscilloscope C1-64, the measurement error cannot be less than ± 5%. The component of the measurement error introduced into the measurement process by the operator is random and cannot be less than ± 5%.

In order to estimate the measurement accuracy provided by the proposed device, we introduce the following notation - LB - EMM winding inductance with a core retracted inside the winding; R is the active resistance of the EMM winding; Lee is the threshold voltage of the operation of the comparison circuit; max is the steady-state current of the EMM winding.

Point 3 (Fig. 4b) reflects the fact that the EMM core has stopped moving, after which the current in the winding begins to increase exponentially.

I Omaks - Icp) in

Jl gn

where r u / rh.

Under the condition t - О for point 3, the current curve (Fig. 4) can be considered that the exponent is close to linear, for which the relation

I Omaks - Icp) -. Tn

Under the action of the indicated current, the voltage U of the RD is formed on the resistive sensor of the current form, which, after amplification, is transformed into a voltage

U 1 Rd k. Thus, U Omax - Icp) RA K x

“

From the above expression, we can find the required delay time for an analog delay circuit, since its value, as mentioned above, determines the accuracy of the device.

The trigger threshold A U of the comparator can be determined from the ratio

R

AU Omaks-Icp) Rd -K-Tj t,

from where

 "

Aulb

(mape cpj K R

For a specific case, when, U 20 МГ, R 20 Ohm, Рд 1 Ohm, К 10,1Макс - 1А, 1Ср 0.5А, we get t с.

Since the response time of such an EMM is at least 3 ms (measured practically), the measurement accuracy provided by the device is 0.033%.

Thus, the proposed device, as compared with the prototype, makes it possible to increase the measurement accuracy of the response time by at least two orders of magnitude due to the fact that the response time of the EMM is determined by comparing the magnitude of the EMM current at a given time with the current value at the previous time this simplifies the measurement process.

Claims (1)

The invention The device for monitoring the response time of the electromagnetic mechanism (EMM), containing a current sensor, meter, leads for connecting the control windings of the EMM, the first and second transistors, the emitters of which are connected to the common bus of the device, the base is connected to the leads for connecting sources of phase-wise signals, the collector of the first transistor is connected to the output for connecting the first EMM control winding, and the collector of the second transistor is connected via a current sensor to the output for connecting the second control EMM winding, characterized in that, in order to increase accuracy, noise immunity and simplify control of the EMM response time, the first and second comparison circuits, a differential amplifier, an analog delay circuit, a digital delay circuit, a trigger, and a current sensor are used in it a resistive current sensor, in parallel with which the specified differential amplifier is connected, the output of which is connected to the first input of the first comparison circuit, the input analog delay circuit and the first input of the second comparison circuit, the second input of which is connected to the output of the analog delay circuit, the second input of the first comparison circuit is connected to the common bus of the device, while the output of the first comparison circuit is connected to the installation R input of the trigger, and the output of the second comparison circuit via a digital delay circuit connected to the clock input of the specified trigger, the direct output of which is connected to the meter input. FIG. one “RIG. J FIG. H