SU618825A1 - Filter regulating device - Google Patents

Description

one

The device relates to electrical engineering and can be used to isolate higher harmonic components in the AC voltage spectrum.

Filter control devices are known.

One of the known devices contains a synchronization circuit, two synchronous filters, a measurement element 1.

The accuracy of the filter setting using the specified device depends on the number of switching capacitors in synchronous filters. Therefore, in order to improve the accuracy of the Tuning, it is necessary to increase the number of switching capacitors, which makes the control device more complex.

The closest technical solution to the invention is a filter adjustment device that contains a synchronization circuit made of a series-connected phase discriminator, an integrator and a controlled oscillator, and a control circuit consisting of a phase-sensitive element, an integrator and. amplifier 2. This device allows you to tune the linear filters to resonance with sufficient accuracy, regardless of the frequency variation of the AC network, as well as when the characteristics of the filter elements change. However, such a device allows the filter to be tuned to resonance, provided that the input signals to its inputs from the current and voltage sensors, during the fine tuning of the filter, are in the same phase, while the filters used in automatic control devices Depending on the circuit design, there may be a shift between the indicated signals during fine construction, ranging from 0 to 90 al. degrees. In addition, the use of a control device containing a synchronization circuit made of a series-connected phase discriminator, an integrator, and a controlled oscillator to control a low-power filter leads to circuit complexity.

The aim of the invention is to improve the accuracy of regulation.

The goal is achieved by the fact that the filter control device is additionally equipped with an amplifier-limiter and phase-matching element, with the input of the limiter amplifier connected to the output

filter, and its output - with the input phase "

  I of the shifting element, the output of the phase-shifting element connected to the first input of the control circuit, and the second input of the control circuit connected to the input of the filter. The drawing shows a block diagram of the filter control device. The device contains a filter 1, amplifier limiting device 2, phase shifting element 3,. control circuit 4, made of phase discriminator 5 and integrator 6, control circuit 7. The device operates as follows. The AC mains voltage U ", containing the higher harmonic components, is fed to the input of filter 1. The filtered voltage of the first harmonic Uf6, x is fed to the input of amplifier 2, which can be used as a null organ. When fine tuning the filter 1, its output to the amplifier-limiter 2 receives a voltage shifted in phase by an angle a with respect to the voltage of the first harmonic supplied from the ac network to the input of the filter 1. The angle a depends on the circuit design of the filter . The limiting amplifier 2 forms a voltage from a given voltage: a straight-line shape that is fed to the input of the phase-shifting element 3. The phase-shifting element 3 shifts this voltage by a certain constant angle (i. The angle value is chosen so that the sum of the angles a plus / J at the adjusted {{ltpra would be -. When finely adjusting the filter, the output of the phase-shifting element 3 will be a rectangular voltage shifted in phase by an angle relative to the phase of the voltage supplied to the input of the filter 1. This voltage out of phase motor element 3 is fed to the input of the phase discriminator 5 of the control circuit 4. The second input of the phase discriminator 5 is supplied with the AC mains voltage Vex. When the filter 1 is tuned, the output signal of the phase discriminator 5 is absent.; If the AC network frequency changes, as well as when the characteristics of the elements included in the filter 1 change, the detuning occurs. As a result, the detuning of the filter 1 causes the magnitude of the angle a (the value of the phase angle between the input and output voltages of the filter 1)

Claims (2)

, , if it is fine tuned, it changes by a certain angle ± A o,. A change in the magnitude of the angle t leads to a change in the magnitude of the phase shift between the first harmonic voltage of the AC mains Ue and the square voltage at the output of the phase shifter 3. The magnitude of the phase shift is becomes more or less value - by the value of Yes. The increase or decrease by the value of L a depends on the sign of the detuning of the filter 1. As a result, the output of the phase discriminator 5 will generate a signal that, through the integrator 6 (as element 6, an amplifier can be used) acts on the control circuit 7. The control circuit 7 under the action of this signal produces a filter trim 1. As a control element 7- for example, a thermal resistance with heating can be used to trim an RC filter. The proposed control device is a filter possesses technical efficiency, it allows the use of precisely maintain filter setting that povyschaet reliability of the devices connected to it. Claims of the invention A filter control device comprising a control circuit consisting of a phase discriminator and an integrator, characterized in that, in order to increase the control accuracy, it further comprises an amplifier-limiter and a phase-shifting element, the input of the limiter amplifier connected to the output of the filter, and the output - with the input of the phase-shifting element, the output of the phase-shifting element is connected to the first input of the control circuit, and the second input of the last - to the input of the filter. Sources of information taken into account in the examination:. 1. USSR author's certificate number 527108, cl. H 02 M 1/12, 1976. 2. USSR author's certificate number 498706, cl. H 02 M 1/12, 1976.