SU424126A1 - DEVICE FOR REGULATING CURRENT CURRENT - Google Patents

Description

one

The invention relates to devices for controlling direct current, for example, electromagnets used in electrophysical installations for creating a constant electric field.

Devices for regulating direct current are known, which contain a multiphase controlled rectifier with a phase control circuit, for which a closed negative feedback on the deviation of the controlled current from the specified value through the nonlinearity unit controls the controlled current and an additional measuring multiphase uncontrolled release A low-pass filter connected to the mains. The voltage from the output of the low-pass filter is fed to the input of the phase control circuit simultaneously with the constant bias voltage so that, at the nominal value of the mains voltage, their actions are mutually compensated. When the mains voltage deviates from the nominal value, the voltage from the output of the low-pass filter becomes greater (less) than the bias voltage, which leads to an increase (decrease) in the ignition angle of the valves, which partially compensates the change in the constant component Ua the rectifier and, therefore, the regulated current Id, due to the voltage deviation f /.,. The disadvantage of such devices is that the accuracy of compensation of the influence of voltage fluctuations {/ l on the regulated current Id is significant

The degrees are determined by small fluctuations in the voltage L.-i and the narrow current control range Id by the reference signal LJo. The reason for this is the non-linear nature of the dependency (U, -i, Ly), where Ly is the input voltage of the phase control circuit, determined by the fact that in the rectifier controlled by the phase-control circuit, there is a pulsing modulation multiphase voltage. Thus, the required value of the compensating signal is nonlinearly related to the voltage A / 7l.

To extend the range of regulation in the proposed device between the circuit

comparison and nonlinearity unit included a dividing element connected to the output of the low pass filter.

The drawing is a block diagram of the onisable device.

The load 1 (electromagnet winding) is connected to the power supply of the t-phase network through the main multiphase rectifier 2, controlled by the help of the valve ignition phase control circuit. To entry 3

Phase Control Circuit Block Connected

4 nonlinearity, to the input of which, through the dividing element 5, is closed negative feedback 6 from the sensor 7 of the controlled current but the deviation of the value of this current from the set voltage f / o. The input 8 of the dividing element 5 through the low-pass filter 9 is connected to the output of the additional measuring multiphase rectifier 10, the input of which is connected to the variable voltage network supplying the transmitter 2.

The change in the linear voltage of the dB network through the rectifier 10 and the filter 9 causes a proportional change in the voltage t / s at the input of the dividing element 5, thereby changing the f / i voltage at the output of the latter so that As a result of a change in the firing angle of the valves, determined by the new value of the f / y nanowire associated with the non-linear function with the voltage U, remains unchanged. Taking into account the setting of the nonlinearity unit 4, the value of the current Id is determined by the expression

J ,, ,,

where KI const;

KU

and,

u, f / l

and

where / sa ki

 const.

t / l

Where it comes from

/.,

where: -Ky- K.-K.

Thus, the value of the current Id does not depend on the voltage Uc, i.e., the effect of the fluctuations of the supply voltage on the regulated current is fully compensated.

When adjusting the current setpoint from zero to the maximum value of the condition of compensation of the considered perturbations by setting the signal Uo, does not change.

Subject invention

A device for adjusting the DC current, containing a multi-phase controlled rectifier, through a current sensor connected to the load, a comparison circuit connected to the sensor and a control voltage source, the output of which is connected to the rectifier input through the nonlinearity unit, auxiliary rectifier A low-frequency enlrom connected to a nitay and its network, characterized in that, in order to extend the control range, a dividing element is connected between the comparison circuit and the nonlinearity unit; with the output of the low pass filter.