SU983556A1 - Valve converter current pickup - Google Patents

Description

(SENSOR OF CURRENT OF THE VENTILATED CONVERTERS

one

The invention relates to electrical engineering, mainly to the measurement of the rectified current of valve transducers of alternating current into constant current.

Known current transducers for valve converters are known, which contain a current measuring transformer (s), the primary winding (circumference, coils) of which is included (included) in the converter power supply circuit, and the secondary (secondary) ones to the load resistor and the filter distributor, }.

The disadvantages of such sensors are the dependence of the output voltage of the sensor in asymmetrical (semi-controlled) circuits on the control angle (rectified voltage) of the gate converter - / the smaller the rectified voltage, the smaller the sensor output signal at a constant current converter; the output voltage is small.

associated with the fact that the current transformer operates in a mode close to a short circuit (low to fault), increasing the load leads to saturation of the transformer and disruption of the linear relationship between the current and the sensor output signal; the large dimensions of current transformers and load resistances, the complexity of installation due to the need for additional 10 connections in power circuits and the decrease in reliability of converters due to this.

The aim of the invention is to improve the accuracy of the sensor by

IS eliminating the influence of the control angle of the converter valves.

The goal is achieved, ts so that the sensor. Current valve converters, containing the measuring

Claims (1)

20, the circuit containing the converter, the filter and the load, as well as the power supply circuit of the valve converters, is provided with an inductive resistance, a switched n supply circuit of the valve converters, and a voltage transformer connected to the primary winding parallel to the inductive resistance, and the secondary winding to the measuring circuit. The drawing shows a diagram of a single phase thyristor converter that supplies the DC motor with a rectified current sensor. The valve converter current sensor contains a voltage transformer 1, a rectifier 2, a resistor 3 and a capacitor, k filter and load 5. The primary winding of transformer 1 is connected parallel to inductive resistance 6, for example, a current-generating reactor. The single-phase thyristor rectifier (valve converter) is thyristors 7 and 8 and diodes 9 and 10 feed a direct current motor 12 through a smoothing choke 11. The sensor operates as follows: Transition (switching of current J from the valve leaving the work to the valve entering operation is carried out through the short-circuit mode. In switching mode, inductive impedance 6 produces voltage pulses Up, the volt-second area of which is proportional to the rectifier to the disconnected current "Switching occurs twice during the half-period of the supply voltage. When the supply voltage passes through zero, the current from the thyristor leaving the work, for example, 8, passes for some time to diode 1 0, and the supply voltage drops at inductive resistance 6. When a tearing pulse is applied to the thyristor 7, the TOIC commutes from diode 9 to the thyristor 7 f and again all the power supply voltage drops at inductive resistance 6, Voltage impulses at current limiting inductive resistance 6 are transformed into the secondary winding of transformer 1, rectifier 2 is passed, filtered by resistor 3 and capacitor K. At the same time, a voltage occurs on load 5, the average value of which is directly proportional to the rectified current. The use of this sensor makes it possible to simplify drive control circuits and reduce their cost, which is significant especially in converters made using a single-phase semi-controlled circuit with current-limiting reactors (up to 10 kW ;. Due to the small switching voltage pulses, the sensor can be used small-sized transformers for increased frequency. Formula of the invention A current sensor for valve converters containing a measuring circuit containing a rectifier, a filter and a load, as well as the supply circuit of the valve transducers, which is related to the fact that, in order to improve the accuracy of the sensor operation by eliminating the influence of the control angle of the converter valves, it is supplied with an inductive resistance included in the supply circuit of the valve transducers and a transformer the voltage connected by the primary winding parallel to the inductive resistance, and secondary to the measuring circuit. Sources of information taken into account during the examination 1. Semiconductor rectifiers. Ed. Kovalev F.I. and Iostkovoy G.P. M., Energie, 1967, p. 256, fig. . R