SU1248000A1 - Method of forced switching of thyristor - Google Patents

Abstract

The invention relates to electrical engineering and can be used for artificial switching of Tiris. tori in power supply systems, electric drive, etc. The aim of the invention is to expand the control range and reduce switching losses. This goal is achieved by controlling the duration of the circuit time for switching off the thyristor 1, i.e. duration of application to tyris-1 of blocking voltage. The control is carried out by changing the duration of the on state of the switching key 3 in direct relation to the size of the switched key measured by the sensor, ka, 5. 1 ill. s (L / 4 ;: 00

Description

The invention relates to electrical engineering and can be used for artificial switching of thyristors in power supply systems, electric drives, etc.

The aim of the invention is to expand the control range and reduce switching losses.

The drawing shows a functional diagram of a device implementing the proposed method.

A device that implements the method of forced switching of the thyristor 1 contains a shunt chain from a series-connected locking voltage source 2 and switching key 3, the control input of which is connected to the output of the shaping amplifier 4. The sensor 5 of the current of the thyristor 1 is connected via a function the converter 6 to the control input of the pulse-width modulator 7 synchronizing input of which is connected to the output of the distributor 8, and the output to the input of the shaping amplifier “4.

In the reference data on thyristors, the dependence of the passport time of turning off the thyristor t on the value of the anode current, which is monotonically increasing, is given. Usually the circuit off time tg is chosen based on the value of tg at the maximum anode current, taking into account the safety factor K:

in with

 t „K

where K 1,2g1,3.

At partial values of the anode current, when const and tg decrease, the safety factor becomes redundant. Therefore, the duration of the thyristor circuit off time also becomes redundant. By keeping the safety factor constant when the anode current is changed, one can get rid of the redundancy of the thyristor off-circuit time.

The device implementing the method of forced switching of the thyristor works as follows.

To turn off the thyristor 3, through which the load current flows, ras. limiter 8 generates a pulse corresponding to the beginning of the switching interval, which is fed to the sync

5 0 5

0

five

0

five

0

five

The downstream input of the pulse-width modulator 7 and the leading edge sets the instant of the onset of the output pulse of the latter. The output pulse of the modulator 7 is fed to the input of amplifier - driver 4, in which it is amplified and shaped to a form depending on the type of switching key 3. Current sensor 5 measures the anode current of thyristor 1, and at its output a signal in the form of proportional to the flowing current, which is fed to the input of the functional converter b, the latter converts it into a control voltage that arrives at the control input of the pshrotnom and mpolator modulator 7 and determines the duration of its output pulse . The on-and-off state of the switching key 3 determines the duration of the circuit off time of the thyristor 1, i.e. the duration of the application of a blocking voltage to the thyristor. Thus, the implementation of the method of forced switching of the thyristor ensures the maintenance of a one-to-one relationship between the value of the anode current flowing through the thyristor and the duration of the switching interval. This eliminates the excessive duration of the switching interval in the modes of the partial values of the anode current, i.e. the closing voltage is applied to the thyristor for such a time as is necessary to lock the thyristor; {with a small margin), with a specific value of the thyristor current in each switch, which allows reducing the amount of energy that is not productively spent on conducting -, mutations, and therefore reduce switching losses.

The adjustment range is the ratio of the maximum duration of the applied voltage to the load to the minimum. The duration of the voltage applied to the load consists of the sum, the capacitance of the conducting state of the thyristor and the key. The duration of the conducting state of the thyristor is determined by the control algorithm, and the duration of the conducting state of the key is variable, its maximum value being equal to (2-1, 3) t5n, where tg is the passport value of the off time

The thyristor is reached at the maximum current of the thyristor.

Thus, the duration of the application of voltage to the load while reducing the anode current of the thyristor is reduced, and the control range is expanded.

Claims (1)

Invention Formula The method of forced switching of the thyristor using parallel-included Composer B, Zhmurov Editor A. Lezhnin Tehred G. Gerber Proofreader L. Patay 4137/55 Circulation 631 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Design, 4., valuable switching controlled key, which includes switching key, characterized in that, in order to expand the control range and reduce switching losses, control the duration of the circuit time of the thyristor by changing the duration of the switched state of the switching key in direct dependence on switched current values.