RU2829328C1 - Ac voltage stabilizer-regulator - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to electrical engineering, in particular to devices providing the required quality of electrical energy for consumers. AC voltage stabilizer-regulator comprises: autotransformer made on two cores, on each core there is one primary and one control windings, secondary winding covers both cores; two units of electronic regulators; control unit; potentiometer; protection unit. Protection unit comprises a constant voltage source, a pulse shaper element, an optotriac, an L-circuit, a magnetic conductor with an air gap, a magnet diode, a voltage divider, a variable resistor, a comparator, a JK trigger and a differentiating circuit.

EFFECT: expansion of functional capabilities with simultaneous increase of reliability.

1 cl, 2 dwg

Description

Field of technology to which the invention relates

The invention relates to electrical engineering, in particular to devices that provide the required quality of electrical energy for consumers.

State of the art

A known AC voltage stabilizer (patent RU No. 2280271, IPC G05F 1/14) contains a step-up transformer, at the output of which a series-connected regulating choke is connected with two parallel-connected coils of different inductance, wound on one closed ferromagnetic core, wherein a variable resistor, regulated by a control unit, is connected in series with the coil with a higher inductance, and a load is connected to the output of the choke.

The disadvantages of this device are limited functionality and low reliability.

Limited functionality is due to:

- excessive unstabilized voltage in idle mode or close to it, i.e. at low load;

- an ineffective regulation system (based on the voltage drop across the choke), associated with the nature of the load (active-inductive, active-capacitive), which does not ensure voltage stability across the load;

- lack of ability to control the value of permissible current.

Low reliability is due to the lack of protection against possible current overload.

The closest analogue-prototype to the claimed technical solution is the AC voltage stabilizer-regulator (patent RU No. 2554712, IPC G05F 1/00).

The AC voltage stabilizer-regulator contains an autotransformer made on two cores, on each core there are one primary and one control winding, the secondary winding covers both cores, the circuit of series and counter-connected primary windings is connected at one end to the network, and at the other to a common connection point of the secondary winding and the load, forming a series connection of the primary and secondary windings, the second end of the secondary winding is connected to a common connection point of the load and the power supply network, to each control winding there are connected blocks of electronic regulators, regulated by a control unit equipped with feedback on the output voltage through a potentiometer, parallel connected to the output winding of the AC voltage stabilizer-regulator.

The disadvantages of this device are limited functionality and low reliability.

Limited functionality is due to the lack of ability to control the amount of permissible current.

Low reliability is due to the lack of protection against possible current overload.

Disclosure of invention

The technical result that can be achieved with the help of the proposed invention is reduced to the expansion of functional capabilities while simultaneously increasing reliability.

The technical result is achieved in that an AC voltage stabilizer-regulator containing an autotransformer made on two cores, on each core there are one primary and one control winding, the secondary winding covers both cores, a circuit of series- and counter-connected primary windings is connected by the second end to a common connection point of the first end of the secondary winding, forming a series connection of the primary and secondary windings, the second end of the secondary winding is connected to a common connection point of the second load terminal and the second wire of the power supply network, electronic regulator units are connected to each control winding, regulated by a control unit equipped with feedback on the output voltage through a potentiometer connected in parallel to the secondary winding of the AC voltage stabilizer-regulator, a protection unit is introduced, wherein: the first and second inputs of the protection unit are connected, respectively, to the first and second wire of the network; the third input is connected to the connection point of the second end of the primary windings, the first end of the secondary winding and the first terminal of the potentiometer; the first output is connected to the first end of the primary windings; the second output is connected to the first terminal of the load.

The protection unit comprises a constant voltage source, a pulse former, an opto-simistor, an L-circuit serving as a single-turn winding of a magnetic circuit with an air gap in which a magnetodiode is located, a voltage divider, a variable resistor, a comparator, a JK trigger, a differentiating circuit, wherein: the first and second inputs of the constant voltage source are connected to the first and second inputs of the protection unit; the zero output of the constant voltage source is grounded; the potential output of the constant voltage source, with a logical one level, is connected to the first terminal of the variable resistor, the C-input of the JK trigger and the first inputs of the voltage divider and the differentiating circuit, the second inputs of which are grounded, and the outputs are connected, respectively, to the first input of the comparator and the J-input of the JK trigger; the second and third terminals of the variable resistor are connected to the second input of the comparator and the anode of the magnetodiode, the cathode of which is grounded; the output of the comparator is connected to the K input of the JK trigger, the Q output of which is connected to the input of the pulse generator, the outputs of which serve as control inputs of the opto-simistor, the input of which is connected to the first input of the protection unit, and the output serves as the first output of the protection unit; the first output of the L-circuit serves as the third input of the protection unit; the second output of the L-circuit serves as the second output of the protection unit.

Brief description of the drawings

Fig. 1 shows the functional diagram of the AC voltage stabilizer.

Fig. 2 shows diagrams of voltage changes on the stabilizer elements. The voltage indices on the diagram, Fig. 2, correspond to the element number in Fig. 1.

Implementation of the invention

The AC voltage stabilizer-regulator (Fig. 1) contains: an autotransformer 1, including cores (magnetic cores) 2 and 3, primary windings 4 and 5, secondary winding 6, control windings 7 and 8; electronic regulator units 9 and 10; control unit 11; control feedback circuit 12; potentiometer 13; protection unit 15, and load 14 is connected to the output of the AC voltage stabilizer-regulator.

On each core 2, 3, of the autotransformer 1, one primary 4, 5 and one control 8, 7 winding are located, respectively. The secondary winding 6 covers cores 2 and 3.

Primary windings 4 and 5 are connected to each other in series in opposite directions. The circuit of primary windings 4, 5 is connected by the first end to the first output of protection unit 15, and by the second end to the common connection point of the first terminal of potentiometer 13, the third input of protection unit 15, the first end of secondary winding 6, the second end of which is connected to the common connection point of the first terminal of potentiometer 13, the first input of control unit 11, the second wire of the power supply network, the second terminal of load 14, the first input of protection unit 15, the second input of which is connected to the third terminal of potentiometer 13. The terminals of winding 6 are the output of the stabilizer-regulator and are connected in parallel to control unit 11 via control feedback circuit 12 through potentiometer 13. Blocks 9 and 10 of electronic regulators, connected to control unit 11, are connected in parallel to control windings 7 and 8.

The first input of the protection unit 15 is connected to the first network wire; the second output of the protection unit 15 is connected to the first load terminal 14.

The protection unit 15 comprises a constant voltage source 16, a pulse generator 17, an opto-simistor 18, an L-circuit 19 serving as a single-turn winding of a magnetic circuit 20 with an air gap in which a magnetodiode 21 is located, a variable resistor 22, a comparator 23, a voltage divider 24, a JK trigger 25, a differentiating circuit 26, wherein: the first and second inputs of the constant voltage source 16 are connected to the first and second inputs of the protection unit 15; the zero output of the constant voltage source 16 is grounded; the potential output of the constant voltage source 16, with the logical one level, is connected to the first terminal of the variable resistor 22, the C-input of the JK trigger 25 and the first inputs of the voltage divider 24 and the differentiating circuit 26, the second inputs of which are grounded, and the outputs are connected, respectively, to the first input of the comparator 23 and the J-input of the JK trigger 25; the second and third terminals of the variable resistor 22 are connected to the second input of the comparator 23 and the anode of the magnetodiode 21, the cathode of which is grounded; the output of the comparator 23 is connected to the K-input of the JK trigger 25, the Q output of which is connected to the input of the pulse generator 17, the outputs of which serve as control inputs of the opto-simistor 18, the input of which is connected to the first input of the protection unit 15, and the output serves as the first output of the protection unit 15; the first terminal of L-circuit 19 serves as the third input of protection unit 15; the second terminal of L-circuit 19 serves as the second output of protection unit 15.

The voltage of the network U ₁ is applied to the input of the stabilizer, voltages U ₄ , U ₅ are induced on the primary windings 4 and 5 respectively, voltage U ₆ is created on the secondary winding 6 and is applied to the load 14. Voltage U _nom is the nominal voltage of the power supply network.

The proposed AC voltage stabilizer-regulator operates as follows.

When power is supplied, since there is no current overload, protection unit 15 ensures the connection of the first network wire to the first end of the primary winding circuit 4, 5.

In normal mode, electric current flows through the series circuit of primary windings 4, 5 and secondary winding 6 of autotransformer 1. This current creates magnetic fluxes in cores 2 and 3. The total magnetic flux of cores 2 and 3 is determined by the magnitude of the supply voltage U ₁ .

Magnetic fluxes of cores 2 and 3 induce voltage U ₄ , U ₅ in primary windings 4, 5, respectively. Voltages are also induced in control windings 7, 8.

The voltage U ₄ of the primary winding 4 coincides in direction with the supply voltage U ₁ , and the voltage U ₅ of the primary winding 5 is opposite in direction. With equality of magnetic fluxes in cores 2, 3 and the same numbers of turns in primary windings 4 and 5, the voltages U ₄ and U ₅ are equal in magnitude and opposite in direction. Consequently, the sum of the voltages (U ₄ +U ₅ ) at the ends of the series circuit of primary windings 4 and 5 is zero due to the opposite connection of windings 4, 5. As a result, the voltage of the secondary winding U ₆ , equal to the network voltage (U ₆ = U ₁ ), is applied to load 14. This mode of operation of the stabilizer corresponds to the nominal voltage in the network (U ₁ = U _nom ). The voltage diagram on the elements of the voltage stabilizer for this mode is shown in Fig. 2a. Control circuit 11, in this mode, gives a command to electronic controller units 9, 10 to set the highest resistances (infinite, i.e. open circuit). Currents in control windings 7, 8 are equal to zero, therefore, demagnetization of cores 2, 3 does not occur.

The no-load current in the primary windings 4 and 5 of the autotransformer 1 at the nominal network voltage U ₁ has a minimum value, since the magnetic flux goes through two cores 2 and 3, the reactive power consumed by the stabilizer from the network is minimal.

When the network voltage U ₁ decreases (and, accordingly, the voltage U ₆ of the secondary winding 6 and the load 14 decreases), a signal of a reduced value for the control system 11 is formed via the feedback circuit 12. At the command of the control unit 11, the unit 10 of the electronic regulator decreases the resistance value. The resistance of the unit 9 of the electronic regulator remains unchanged and large. In the control winding 7, closed to the resistance of the unit 10 of the electronic regulator, a current flows, creating a counter magnetic flux, decreasing the magnetic flux in the core 3. Due to the condition of the invariance of the value of the total flux in both cores 2 and 3, respectively, in the core 2 the magnetic flux increases due to the forced decrease in the magnetic flux in the core 3. In the primary windings 4 and 5, an opposite change in voltage also occurs. Voltage U ₄ increases and U ₅ decreases, the sum of these voltages is not equal to zero (U ₄ +U ₅ >0) and is released at the ends of the circuit of primary windings 4, 5. The sum of voltages U ₄ and U ₅ coincides in phase with the network voltage U ₁ and is added to it, compensating for its decrease. This ensures voltage stability on the secondary winding 6 (U ₆ =U _nom ) and load 14 (U ₁ +(U ₄ +U ₅ )=U ₆ =U _nom ). This mode corresponds to the voltage diagram in Fig. 2b. The transition of the stabilizer to a reduced network voltage occurred smoothly without switching in the power circuits of both the supply and the load, that is, without interruptions in power supply, without switching and without distortion of the sinusoidal voltage shape.

When the network voltage U ₁ decreases to the limit, the resistance of the electronic regulator unit 10 decreases to zero. In this case, the control winding 7 becomes short-circuited. The magnetic flux in the core 3 becomes equal to zero due to the short-circuited state of the control winding 7. In this case, the voltage U ₅ of the primary winding 5 is equal to zero.

The entire total magnetic flux passes through the core 2, the maximum increase in the network voltage U ₁ is created only by the voltage U ₄ of the primary winding 4. The sum of the reduced network voltage U ₁ and the voltage of the primary winding 4 (U ₁ +U ₄ =U ₆ =U _nom ) provides a stable voltage U ₆ =U _nom on the secondary winding 6 and the load 14, Fig. 2c.

When the network voltage U ₁ increases, the voltages U ₆ in the secondary winding 6 and on the load 14 begin to increase accordingly. In this case, the control process occurs as follows. A signal proportional to the beginning increase in the value of the voltage U ₆ is sent to the control unit 11 via the feedback circuit 12. At the command of the control unit 11, the resistance value of the electronic regulator unit 9 decreases. In this case, the resistance of the electronic regulator unit 10 remains unchanged and has the greatest value (infinity).

In the control winding 8, closed to the block 9 of the electronic regulator, a current flows, decreasing the magnetic flux in the core 2. Due to the condition of invariance of the value of the total flux in both cores 2 and 3, respectively, in the core 3 the magnetic flux increases due to the forced decrease in the magnetic flux in the core 2. In the primary windings 4 and 5, the opposite change in voltage also occurs. The voltage U ₅ increases, and U ₄ decreases, the sum of these voltages is not equal to zero and is released at the ends of the circuit of the secondary windings 4, 5. The sum of the voltages U ₄ and U ₅ is in antiphase with the network voltage U ₁ and is a reducing voltage for it, compensating for its increase. This ensures voltage stability on the secondary winding 6 (U ₆ = U _nom ) and load 14 (U ₁ - (U ₄ + U ₅ ) = U ₆ = U _nom ). This mode corresponds to the voltage diagram in Fig. 2g. The stabilizer's transition to increased network voltage occurred smoothly without switching in the power circuits of both the supply and the load, that is, without interruptions in power supply, without switching, and without distortion of the sinusoidal voltage shape.

At the maximum increase of the network voltage U _1, the resistance of the electronic regulator unit 9 and the voltage U ₄ of the primary winding 4 decrease to zero. In this case, the control winding 8 becomes short-circuited. The magnetic flux in the core 2 becomes equal to zero due to the short-circuited state of the control winding 8. In this case, the voltage U ₄ of the primary winding 4 is equal to zero.

The entire total magnetic flux passes through the core 3, the maximum decrease in the network voltage U ₁ is created only by the voltage U ₅ of the primary winding 5. The difference between the network voltage U ₁ and the voltage of winding 5 (U ₁ -U ₅ = U ₆ = U _nom ) ensures a stable voltage U ₆ = U _nom on the secondary winding 6 and load 14. The voltage diagram in Fig. 2d corresponds to this mode.

In real stabilizers of network voltage with constant voltage of the power supply network U ₁ , but with a change in the value of the load resistance 14, a change in the value of voltage U ₆ on the secondary winding 6 of the autotransformer 1 also occurs. This is due to a change in voltage drops on the active and inductive resistances of the stabilizer itself. The proposed device also ensures voltage stabilization on the load when its value changes.

The output voltage on the load 14 is regulated, regardless of the input voltage, using the potentiometer 13. By changing the resistance ratio of the potentiometer 13, the required output voltage value is set. A signal proportional to the set voltage value on the resistance of the potentiometer 13 is sent to the control unit 11 via the feedback circuit 12. The control unit 11 regulates the output voltage using the electronic regulator units 9 and 10.

As shown above, at the moment of supplying power to the stabilizer, protection unit 15 ensures the connection (switching) of the first network wire to the first end of the primary winding circuit 4, 5, and therefore the power supply of load 14. The switching itself is caused by the operation of opto-simistor 18 on command from pulse generator 17.

Due to the establishment of a logical zero level at the K input, and a logical one level at the C input, J input, and therefore at the Q output of the JK trigger 25.

The logical one level at the C-input of the JK trigger 25 is determined by the potential from the output of the constant voltage source 16.

The logical one level at the J-input of the JK trigger 25 is caused by a voltage surge at the output of the differentiating circuit 26 at the moment the potential is supplied from the output of the constant voltage source 16.

The logical zero level at the K-input of the JK trigger 25 is caused by the non-operation of the comparator 23 (due to the absence of a current overload).

The comparator 23 is triggered under the condition

U _MD >U _DN (1),

where U _MD is the voltage drop at the base of magnetodiode 21, supplied to the second input (U _in+ ) of comparator 23;

U _DN is the voltage from the output of voltage divider 24, supplied to the first input (U _in- ) of comparator 23.

The output voltage of the voltage divider 24, U _DN , is proportional to the output voltage of the DC voltage source 16.

The voltage drop across the base of magnetodiode 21, U _MD , is determined by:

- the value of the output voltage of the DC voltage source 16;

- resistance of variable resistor 22;

- the resistance of the base of the magnetodiode 21, depending on the magnitude of the transverse magnetic field.

And since the resistance of the base of the magnetodiode 21 increases with the increase of the transverse magnetic field, the value of which is determined by the value of the load current of the stabilizer flowing in the L-circuit 19, which serves as a single-turn winding of the magnetic circuit 20 with an air gap, the moment of operation of the comparator 23 will be determined by the value of the load current and the pre-set value of the resistance of the variable resistor 22.

Which, in turn, ensures:

- control of the value of the permissible load current;

- protection against possible current overload,

and therefore expansion of the stabilizer’s functional capabilities while simultaneously increasing reliability.

Claims (1)

An AC voltage stabilizer-regulator comprising an autotransformer made on two cores, on each core there are one primary and one control winding, the secondary winding covers both cores, a circuit of series- and counter-connected primary windings is connected by the second end to a common connection point of the first end of the secondary winding, forming a series connection of the primary and secondary windings, the second end of the secondary winding is connected to a common connection point of the second load terminal and the second wire of the power supply network, units of electronic regulators are connected to each control winding, regulated by a control unit equipped with feedback on the output voltage through a potentiometer connected in parallel to the secondary winding of the AC voltage stabilizer-regulator, characterized in that a protection unit is introduced into the device, wherein: the first and second inputs of the protection unit are connected respectively to the first and second wire of the network; the third input is connected to the connection point of the second end of the primary windings, the first end of the secondary winding and the first terminal of the potentiometer; the first output is connected to the first end of the primary windings; the second output is connected to the first terminal of the load, the protection unit comprises a constant voltage source, a pulse former, an opto-simistor, an L-circuit serving as a single-turn winding of a magnetic circuit with an air gap in which a magnetodiode is located, a voltage divider, a variable resistor, a comparator, a JK trigger, a differentiating circuit, wherein: the first and second inputs of the constant voltage source are connected to the first and second inputs of the protection unit; the zero output of the constant voltage source is grounded; the potential output of the constant voltage source with a logical one level is connected to the first terminal of the variable resistor, the C-input of the JK trigger and the first inputs of the voltage divider and the differentiating circuit, the second inputs of which are grounded, and the outputs are connected respectively to the first input of the comparator and the J-input of the JK trigger; the second and third terminals of the variable resistor are connected to the second input of the comparator and the anode of the magnetodiode, the cathode of which is grounded; the output of the comparator is connected to the K-input of the JK trigger, the Q output of which is connected to the input of the pulse generator, the outputs of which serve as control inputs of the opto-simistor, the input of which is connected to the first input of the protection unit, and the output serves as the first output of the protection unit; the first terminal of the L-circuit serves as the third input of the protection unit; the second terminal of the L - circuit serves as the second output of the protection unit.