SU886326A2 - Adjustable thyristorized ac voltage converter for two active heaters - Google Patents

Description

(54) ADJUSTABLE THYRISTOR TRANSFORMER

AC VOLTAGE FOR TWO ACTIVE

HEATERS

one

The invention relates to alternating voltage converters and can be used to control two active heaters, and for example, as an actuator of temperature controllers for industrial resistance electric heaters.

According to the main author. St. No. 682987, there is a known variable thyristor converter of alternating voltage for two active heaters, containing three thyristors, two of which are connected in series with one heater, and the third between the common points of the heaters and the indicated two thyristors. One of the thyristors is connected to the phase clamp of the supply network by the anode, the second - by the cathode, and the third thyristor is connected by the anode to the cathode of the first thyristor, the cathode - to the anode of the second thyristor. When less than half of the maximum power is consumed, pulses are fed to the first and second thyristors and change their control angle, and when more than half of the maximum power is consumed, control pulses are sent to all the thyristors, and to the first and second, at their natural clamping angles, and pulse control angle on the third thyristor 1.

The disadvantages of the known device are a lower power factor and a high level of higher harmonics of the current generated by the converter in the network in the upper part of the regulation characteristic.

The purpose of the invention is to increase the energy performance of the converter by introducing an additional control section, since the power factor is equal to one at the boundaries of the control sections.

This goal is achieved by the fact that each heater is made of two sections connected in series, and an additional thyristor is turned on between the points of connection of sections of each heater polarity equal to the third thyristor.

The drawing shows a diagram of the proposed device.

Heaters 1 and 2 are connected to the same power supply terminal through thyristors 3

and 4, and to the second - directly. The cathode of the thyristor 3 and the anode of the thyristor 4 are connected through the thyristor 5. The heater 1 is made of two sections 6 and 7, and the heater 2 is made of sections 8 and 9, the thyristor 10 is connected between the connection points of sections 6, 7 and 8, 9 same with thyristor 5.

The device works as follows.

As well as in the well-known in the first adjustment area, the pulses are applied to the thyristors 3 and 4 and change their adjustment angle. In the second and third adjustment sections (as well as in the second known section), these thyristors are unlocked at the corners of their natural ignition. In the second section, control pulses are applied and the angle of regulation of the additional thyristor 10 is changed in the open state of thyristors 3 and 4.

In the third control section, the thyristors 3 and 4 and the additional thyristor 10 are unlocked (control pulses are applied) at the corners of their natural ignition, and the power consumption is adjusted by changing the control angles of the thyristor 5.

The introduction of an additional control section increases the power factor of the thyristor converter reduces its negative impact on the supply network and other consumers.

Claims (1)

Invention Formula Adjustable thyristor alternating voltage converter for two active heaters according to the author. St. No. 682987, characterized in that, in order to increase the power factor by introducing an additional adjustment section, each heater is made of two sections connected in series, and an additional thyristor is connected between the points of connection of the sections of each heater, polarity equal to the third thyristor. Sources of information taken into account in the examination I. USSR author's certificate number 682987. CL. H 02 M 5/04, 1977.