SU403042A1 - THYRISTOR AMPLIFIER - Google Patents

Description

The invention relates to the field of automatic regulation and control and can be used, for example, to control the heating of induction furnaces, to control induction heating of reactors, etc.

A thyristor amplifier (TU) is known, which contains a series-connected power supply source and a thyristor unit, the control input of which is connected to the output of a pulse-phase modulator.

The known devices have a non-linear conversion function according to the level of the effective value, while using TU to heat the objects in some cases requires a linear conversion function. In known devices, the instability of the amplitude of the supply voltage introduces additional error. On the other hand, to linearize the TU transformation function by the effective value level, it is necessary to double the amount of equipment (quad devices and sign inverters), which complicates the circuit.

In order to linearize the conversion function while simultaneously improving the accuracy and linearization of the conversion function by the level of the effective value of the output voltage in the proposed thyristor amplifier, one quadrant device controlled by the focal input is used. The quadting device performs the operation of squaring the voltage applied to its signal (quad) input and the operation of dividing by the voltage applied to its focal (dividing) input. A control signal is supplied to the focal input of the squaring device, and a voltage is applied to the signal input through the passive circuit.

FIG. I presents the scheme with the proposed thyristor amplifier; in fig. 2 - supplying sinusoidal voltage U (ti) t) and output signal 6 (/) of the thyristor amplifier.

The proposed thyristor amplifier consists of a phase-pulse modulator 1 (a converter of a control voltage Ly to a phase f of an electrical signal), a thyristor unit 2, and a source 3 of a sinusoidal supply voltage

U (wf)

Adjusting the effective U value of the output signal of the (/) thyristor amplifier (TU) is carried out by changing the unlocking angle of the thyristor in the thyristor block 2. With the thyristor open, the signal from the source 3 of the supply voltage passes to the output of the TU (to the load of the device). At the output of the TU there is a piecewise sinusoidal voltage, the form of which is shown in FIG. 2

The device works as follows.

The control (input) voltage YY of the negative polarity is simultaneously applied to the adder 4 and to the focal (dividing) input of the quadrating device 5, to the squareing (signal) input of which a signal from the source 3 of the supply voltage is supplied to the quadrant (signal) input . The quadting device 5, controlled by the focal input, performs the operation of squaring the signal applied to its signal input, and the division operation by the signal applied to its focal input, i.e., the output signal is defined by the expression

and (and /) :: .and (w) / 2p - (s t} l2SUy,

where p SUy is the focal parameter (the distance from the focus of the parabola to its direct entry);

25 is the focal input gain.

A quadrature device, controlled by the focal input, can be implemented on the basis of a multiplying-dividing device, or on the basis of a linear-segment approximator. The coupling UK from the output of the device 5 is fed to the second input of the adder 4 and to the input of the inverter 7 characters with a transfer coefficient of -1. With a positive polarity of the control voltage, instead of the adder 4, a subtractive device must be used.

In each period of the supply voltage, the device operates in two cycles. In the positive half-periods of the supply voltage, the key 8 is in the upper (according to the drawing) position and the voltage (CC-Uy from the output of the adder 4 is fed to the input of the integrator 9. The voltage e (co /) at the output of the integrator 9 increases. With and key 8 using block 10 (control) switches to the lower position, and the coupling at the output of the integrator 9 begins to decrease. When the output voltage of the integrator reaches zero, i.e. at e (w /) e (+ f) 0, the comparator (threshold device) 11 generates a pulse opening thyristor in the thyristor unit 2. during intervals L; - | ip D) 2 thyristor is open, and the signal from the power supply voltage is output specification. At the start of the next supply period, the capacitor 9 of the integrator is discharged. When key 8 is switched to the upper (according to the drawing) position, and the conversion cycle

begins again but the algorithm described above. The effective value U of the output signal TU is determined by the expression

where / (У5 / | 3 is the gain coefficient of the TU.

Thus, the TU transformation function at the effective level is linear and does not depend on the amplitude Urn of the supply voltage U (t) and on the time constant of the integrator 9. The latter is provided by changing the direction of integration in each period of the supply voltage.

Subject invention

A thyristor amplifier, containing a series-connected power supply sinusoidal voltage and a thyristor unit, the control input of which is connected to the output of the phase-impulse modulator, performed on a quadrating device, adder, inverter, control unit and serially connected to the key, integrator and comparator, the output of the quadrant device is connected to two key inputs, respectively, through an adder and an inverter, and the key control input is connected to the source via a control unit, ex Due to the fact that, in order to increase reliability while increasing the accuracy and linearization of the conversion function by the level of the effective output voltage, the quadrature input is connected to the input of the thyristor amplifier, and the quadrature signal input is connected to the power supply through an additional passive circuit .

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