SU661381A2 - Frequrncy sensor - Google Patents

Description

(54) FREQUENCY SENSOR

one

The invention relates to a measurement technique and can be used both for recording purposes and for controlling the frequency (rotational speed) of autonomous generating sets and AC stations.

A frequency to voltage converter is known, which consists of a driver, a frequency divider into two, an output amplifier, and two selectively connected circuits, each of which includes a converter and an analog switch 1.

However, this transducer has a low measurement accuracy, especially in the range of small frequency deviations.

According to the main author. St. No. 549753, a frequency sensor is known, consisting of a pulse generator, a standby pulse generator of a reference duration, a comparison unit, a memory unit, an integrator and an amplifier, which has an increased measurement accuracy.

However, when measuring the frequency in some transient processes, where the appearance of an aperiodic component in the voltage of the measured frequency is possible, for example.

the short circuit mode in the power network or when the sensor operates with the network through a matching transformer, the measurement accuracy of such a frequency sensor will decrease. This is due to the fact that the aperiodic component of the voltage can significantly distort the magnitudes of the half-period of the voltage, which will affect the operation of the sensor.

The aim of the invention is to improve the measurement accuracy in transients with the presence of an aperiodic component in the voltage of the measured frequency while maintaining the frequency of measurements.

The goal is achieved by the fact that the sensor frequency auth. St. No. 549753, containing a series-connected standby pulse generator of a reference frequency, a comparison unit, an integrator, a memory unit and an amplifier, as well as a pulse shaper, the output of which is connected to the second input of the memory unit and the input

The standby pulse generator is connected to the second input of the comparator unit, a delay block is inserted, connected between the output of the pulse shaper and the input of the standby pulse generator.

The drawing shows the functional diagram of the frequency sensor.

The sensor contains a pulse shaper 1, a delay unit 2, a waiting generator 3, a comparison unit 4, an integrator 5, a storage unit 6 and an amplifier 7.

The frequency sensor works as follows.

Pulse shaper 1 converts a sinusoidal input (investigated) signal or a signal with the presence of an aperiodic component into square-shaped pulse signals, the duration of which is equal to the duration of the time interval between zero voltage values, in particular, with a purely sinusoidal signal - half-period. The pulse frequency coincides with the frequency of the input signal (f Y) On the leading edge of each pulse of the imaging unit 1, a delay unit 2 starts its operation, which forms rectangular pulses of a certain duration at its output. The pulse duration (delay time) of block 2 is chosen for convenience of approximately 0.5 T nom.

On the falling edge of the indicated pulses, a waiting generator of 3 pulses of the reference duration is triggered.

The signals from the delay unit 2 and the standby generator 3 pulses of the reference duration arrive at the input of the comparator unit within one period of the input signal. Next, the sensor works similarly to the known.

Thus, using fe the proposed delay block frequency sensor increases the measurement accuracy in transients with the presence of an aperiodic component in the voltage of the measured frequency while maintaining the frequency of the measurements.

Claims (1)

1. US patent No. 372571, CL. 307-64, 25 1971. one 6 7