SU373829A1 - COMPOUND CAMERA - Google Patents

Description

Compounding devices are known for maintaining a constant extinction angle of the inverter valves, comprising a pulse shaper and operating on the principle of an open-loop control system. However, such devices do not provide the necessary stability of the extinction angle. The proposed device allows you to maintain the extinction angle unchanged in the established and transient modes, with uncontrolled changes in the parameters of the control system, as well as when changing the parameters of the switching circuit of the valves, inverter. This is achieved by incorporating elements that form a leading angle, phase shift, and a compounding signal into a closed control system that stabilizes the parameters of these elements. The drawing is a schematic diagram of the described device consisting of a power transformer /, an measuring current transformer 2, a measuring current transformer 3, an inverter 4, a measuring voltage transformer 5, an amplifier. 6 control pulses, pulse generator, containing the adder of input signals 7, element 8, the current effect of the compounding device; phase shifter 14, synchronous detector 15. The device operates as follows. The voltage from the output of the measuring transformer 5 goes to block 9, where it is rectified using a 24-phase rectifier circuit, i.e. the output voltage of unit 9 is almost without inertia following the value of the switching voltage of the valve. The voltage Uo from block 9 is fed to the input of the gauge 13 of the advance angle Ro. The angle PO is measured by fixing two points in time: 1) the moment of equality of the alternating voltage of the phase-shifting device 14- / p to the constant voltage UQ; 2) the moment of the switching voltage switching / k through zero. The voltage corresponding to the angle r0 is compared with the voltage of the device // setpoint, which corresponds to the given angle of quenching. B. The deviation of the angle Ro from the angle b is determined by the voltage i / o and occurs only because of the error of block 9.

Therefore, the error signal arrives at block 9 and changes its transmission coefficient in one direction or another. This causes a corresponding change in the voltage t / o, so that the error in the Ro angle decreases to zero.

The change of the transmission coefficient can be made, in particular, with the help of an ND voltage divider consisting of two thermal resistances with indirect heating, to which the voltage UQ is applied. From one of the thermistors, the voltage is applied to the input of the block 7. The signal of the angle regulator ro from the summing device 12, depending on the sign, is fed to one of the thermal resistances of the block 9, as a result of which the voltage at the input of the block 7 changes. C proportional to UQ and, therefore, to the switching voltage.

Correction of the QA current element, for example, due to a change in the parameters of the switching circuit, is also introduced by changing the transmission coefficient of the current element.

For this, the meter 10 determines the actual value of the extinction angle by fixing two points in time:

1) the moment of cessation of current through the valve;

2) the moment when the commuting voltage passes through zero.

Since the regulator Ro angle completely corrects the error in the extinction angle, which is caused by the error of the voltage block 9, only the error caused by the incorrect operation of the element 8 remains in the extinction angle.

Therefore, the error signal is introduced into the element 8 to change its transmission coefficient in one direction or another, like changing the transmission coefficient of block 9.

The voltage that comes from the phase-shifter 14 to the input of block 7 must be shifted exactly by 90 el. gr. in relation to the switching voltage. To eliminate the error of the phase-shifting device and the exact phase shift by 90 °, the phase-shifting device is provided with the aid of a synchronous detector / 5. The constant component of our voltage at the output of a synchronous detector is zero in the case of a phase shift of two voltages applied to it by 90 °. If there is a constant voltage component at the output of the synchronous detector 15 in the phase-shifting device, one of the resistances of the C-chain changes and the phase of the voltage entering the input of the unit 7 changes in the appropriate direction.

Subject invention

A compounding device for adjusting the extinction angles of the inverter valves, containing a pulse shaper, to the input of which are connected the outputs of a voltage sensor that reacts to the switching emf value, a current sensor that reacts to the value of the inverted current, the phase-shifting unit that generates an alternating voltage, proportional switching emf with a shift of 90 e. gr. in relation to the latter, characterized in that, in order to ensure accuracy of the device operation when changing its parameters or the reactance of the switching circuit in conditions of dramatically varying switching voltage and inverting current, it is connected to a synchronous detector with an initial angle measurement unit advance, the block of measurement of the angle of extinction and the block of setting the angle of extinction. The phase-shifter output is connected to the input of the initial angle angle gauge and via a synchronous detector to the control The phase-shifting input, the voltage sensor output is connected to the control input of the voltage sensor through the front angle meter and the reference element, and the output of the angle meter off is connected via another comparison element to the control input of the current sensor and the settings block outputs are connected to the inputs of the comparison unit. extinction angle and advance angle.