SU1644108A1 - Pulsed current controller for active/inductive loads - Google Patents

Abstract

The invention relates to secondary power sources and can be used in automation, electrical drive and electronics. The purpose of the invention is to increase the stability of the work. The goal is achieved by introducing into the circuit an additional threshold element 10, a rectifying element 6 and the corresponding execution of the logic unit. In this case, element 10 makes it possible to fix the sign of the difference between the current in the RL load and the control signal, which, in total with the proposed implementation of the logic unit, allows to increase the work stability. 1 il.

Description

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The invention relates to electrical engineering, in particular, to converter technology, and can be used in the construction of impulse stabilizers and current regulators in an active-inductive load, as well as more complex stabilizers and regulators in which the output coordinate is controlled by the intermediate coordinate current through the line choke. Such stabilizers and regulators are widely used in automation, in electric drives, in electronics and other areas of technology.

The purpose of the invention is to increase the stability of the work.

The drawing shows a functional diagram of a pulse current regulator for active-inductive loads.

The regulator has a power switch 1, the output of which is connected to the RL-load 2 with a counter-EMF source. In the particular case, the source of anti-EMF may be absent. Power switch can be performed by any scheme, for example in the form of a serial key and a shunt diode (see Fig.1) or in the form of a bridge. The load circuit includes a current sensor 3, made, for example, in the form of a measuring resistor. The control unit of the controller contains a comparison amplifier 4, an integrator 5, a rectifying element 6, a computing unit 7, an adder 8, three threshold elements 9-11, two elements 12 and 13, and an RS flip-flop 14. At the inputs of the comparison amplifier 4 are connected current sensor 3 and the control (reference) signal Ј ,. Exit Comp &

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The amplifier amplifier is connected to the inputs of the integrator 5, the computing unit 7 (via the rectifier element 6) and the threshold element 10. The output of the integrator is connected to the input of the threshold element 9 and one of the inputs of the adder 8, to the other input of which the output of the computing unit is connected. Voltages and (in the case of two-pole modulation) and counter electromotive force are also supplied to the inputs of the computing unit. The output of the adder is connected to the input of the threshold element 1I. To the S-input of the trigger 14 is connected the output of the element 12, to the inputs of which the outputs of the threshold elements 9 and 10 are connected, and the inverse output of the trigger. The output of element I 13 is connected to the R input of the trigger, the inputs of which are connected to the output of the threshold element 11 and the direct output of the trigger. The trigger outputs are connected to the control inputs of the keys of the power switch 1. If the switch is complete in the form of a bridge, then both trigger outputs are used. If the key is one (see Fig. 1), only the direct trigger output is used. All circuit elements are typical. A comparison amplifier, integrator, adder can be performed on operational amplifiers. The rectifying element 6 can be made on a diode or on an operational amplifier. Computing unit 7 consists of multiplier 15, adders 16,17, scaling unit 18 and divider 19.

The regulator works as follows.

During the first interval of the control cycle, when the trigger 14 is in state 1, the keys of the bridge switch are in the state corresponding to 1 ° + Un, where U, is the voltage at the output of the controller; Un - supply voltage. The current in the load increases. The signal Q (t) at the output of integrator 5 at. Also increases from zero, where iI is the current load current; i, is the control signal. Due to the presence of a rectifying element 6 with i,: i, i.e. at, signal Dt. the input of the computing unit is not received, -At the output of this unit, the signal is valid

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Q |, (t 2tU. (T "-) + l (t)

where Lw is the load inductance;

T, is the duration of the control cycle;

1 - counter electromotive force voltage, which is always positive. Therefore, the sum signal at the output of the amplifier 3 Q is also positive, the threshold element 11 is in the state O. At i c i the signals Q (t), Q (t) and Qg-U) begin to decrease. When Q "(t) is 0, the threshold element 11 switches to state 1, a single signal through element 13 arrives at the H input of the trigger 14, converts the trigger to the zero state. The switches of the bridge switch switch to the state corresponding to U and the current of element I 13 is set to O. The current (, begins to fall. At ik "ii, threshold element 0 is in state 1, and the signal Q at the output of integrator 5 begins to grow. When Q (t) 0, the threshold element 9 switches to state 1, element I 12 sends the trigger signal S to the S input of the trigger, the trigger switches to the unit state. The conversion cycle ends. Since the integral of the current difference ii

and control signal i for this

the cycle is zero then the average

current

H

and signal i,

for this beat

equal to each other. Moreover, if U. (t), l "t) and ij, (t) remain constant during the second interval of the conversion cycle, the current i, at the end of the cycle, differs from the if signal by an amount close to the specified value D1c (T ;). The management process will be sustainable. In the proposed scheme, with maximum speed, all changes of the control signal i are processed, while the control process remains stable, and the stability is not affected by changes in the supply voltage of 1K and the back emf.

For example, if the signal it sharply increases at time t following the moment of switching the power switch to the state corresponding to U-lJh (trigger 14 in the zero state), and if the signal Q (t) remains positive during the time interval corresponding, then after the signal: exceeds the value of current i, the threshold element is triggered

10, a single signal is formed at the output of the element AND 12, the trigger 14 is switched to the single state. At the output of the power switch, the voltage Uj + is set, the current iI starts to increase. The system maintains a steady auto-oscillation mode, during which the control goal is realized in each clock cycle. Thus, a pulse current regulator for actively inducting load allows to obtain high accuracy of current control with high speed and good process stability. The use of the regulator is especially effective in conditions of strong interference from the power supply and load side and with rapid changes in the control signal.

Claims (1)

Invention Formula Pulse current regulator for active-inductive load, containing a power switch, a load current sensor that compares the amplifier, the inverting input of which is connected to the output of the current sensor, and the non-inverting input to the output for connecting a control signal source, the integrator, to the input of which is connected comparing amplifier, computing unit, which forms the integral value of the difference between the load current and the control signal for the time interval from the current time to the end so five five 0 five This conversion, provided that the switch's power switches are switched at the current time, and at the end of the conversion cycle, the difference between the load current and the control signal takes a predetermined value, the summing amplifier, to the inputs of which the outputs of the integrator and the computing unit are connected, two threshold elements to the integrator output is connected to the input of the first one, and the summing amplifier output is connected to the input of the second one, and the logic unit, to the inputs of which the threshold elements are connected, and the output is connected n to the control inputs of the switches of the power switch, which is the case with the aim of increasing the stability of the operation, a third threshold element is inserted in it, the input of which is connected to the output of the comparison amplifier, which The copulative element is connected to the input of the computing unit, and the logic unit is made on an RS trigger and two elements AND, the S input of the trigger is connected to the output of the first element AND, to the inputs of which are connected the outputs of the first and third threshold elements and the inverse output RS of the trigger, and R-in od latch connected to the output of the second AND gate, whose inputs are connected to the output of the second threshold element and a forward output latch, the latch outputs are logic block outputs.