RU2772321C1 - Method and apparatus for synchronising a voltage converter control system - Google Patents

Abstract

FIELD: power engineering.

SUBSTANCE: invention relates to power converter apparatus control systems and can be used as a synchronisation apparatus in three-phase controlled bridge rectifiers and for synchronisation in digital and analogue valve converter control systems. The substance of the proposed method and apparatus for synchronising a voltage converter control system consists in forming an initial synchronising voltage as a result of two-level division of the phase voltage half-wave and comparison thereof, synchronising digital (analogue) valve converter control systems and three-phase controlled rectifiers.

EFFECT: claimed method and apparatus increase the accuracy of voltage synchronisation, simplify the synchronisation circuit of a voltage converter control system, and increase the operating reliability thereof.

2 cl, 5 dwg

Description

The invention relates to control systems for power converters and can be used in three-phase controlled bridge rectifiers, as well as in digital and analog control systems for valve converters.

A known method of controlling rectifiers, in which the sync pulses are generated at the time of comparing the linearly controlled and reference voltages. The reading of the level of linearly varying voltage starts from the moment of natural switching of the valves (G.N. Gorbachev, E.E. Chaplygin. Industrial electronics. - M.: Energoatomizdat, 1988, 320 p.).

The disadvantage of this method is the need to shift the AC voltage of each of the phases at an angle of 30°, corresponding to the point of natural switching valves, which does not improve the accuracy of voltage synchronization.

There is also known a method for synchronizing the converter control system, in which the synchronization voltage is applied to the input of the comparator through two series-connected integrators operating in antiphase and generating voltage pulses with a duty cycle equal to two (see RF patent No. 2107981, IPC H02M 1/08 (1995.01), published 03/27/1998).

The disadvantage of this method is the accumulation of integration errors, which leads to saturation of the integrator.

The closest analogue (prototype) in terms of technical essence to the proposed method is a method for synchronizing a digital control system (see RF patent No. 2417507, IPC H02M 1/08 (2006.01), publ. 27.04.2011).

In the above method, the control clock is generated by comparing the filtered clock voltage with a reference signal (voltage). To reduce the cumulative integration error, the rate of rise and fall of the signal at the input of the integrator is changed. In addition, there is no need to generate a reference voltage and compare it with a filtered clock voltage.

The disadvantages of this method are: the complexity of the circuit due to the presence of two integrators and the need for periodic adjustment of the integrators during operation.

A control device of a three-phase controlled rectifier is known, consisting of a linear control voltage generator, a control pulse shaper, a phase voltage comparison device, switching gate selection circuits, and a shift register. The key elements of the rectifier are fully controlled gates - transistors (see RF patent No. 2279178, IPC H02M 7/162 (2006.01), publ. 06/27/2006).

The disadvantage of this device is a small range of regulation of the output voltage.

It is also known device rectifier with a midpoint; in each arm of the cathode and anode groups, two diodes are connected, transistors are connected to the junction point of which, forming the middle point. The midpoint also includes capacitors connected in series. Adjustment of the voltage level is carried out by synchronous switching of transistors (see US patent No. 7,196,919 B2, publ. 03/27/2007).

The disadvantage of this device is that the voltage equalization in the positive and negative parts of the source is carried out by transistors with a small range of output voltage regulation.

It is also known a device for a synchronous voltage regulator made on a QFN36 chip for controlling a three-phase bridge inverter (see the patent Yap. SI-6633C, publ. 21.04.2016).

The disadvantage of the device is its complexity, the presence of a large number of components and the need to use specialized chips and drivers.

The closest analogue (prototype) in technical essence to the proposed device is a device for controlling a valve converter, containing a thyristor bridge rectifier, a voltage source, low-power three-phase bridge rectifiers, pulse peak transformers and a load (see RF patent No. 1066025, IPC H02P 13/ 16 (2000.01), publ. 07.01.1984).

The disadvantages of this device are the presence of a large number of winding elements and low accuracy of voltage synchronization.

The technical result achieved using the claimed method of synchronizing the control system of voltage converters and the device for its implementation is to increase the accuracy of voltage synchronization, simplify the synchronization circuit of the control system of voltage converters and increase the reliability of its operation.

In the claimed method, this technical result is achieved by the fact that in the well-known method of synchronizing the control system of voltage converters, which consists in the fact that sync pulses are generated by comparing the filtered synchronizing voltage with the reference voltage, the initial synchronizing voltage is calculated by dividing the phase voltages, and the half-wave of the phase voltage is additionally divided into two levels, at the first of which, the half-wave of the phase voltage is compared with the voltage of natural switching of the converter circuit, and at the second level, the rectified phase voltage is compared with the turn-on voltage of a galvanically isolated electronic element, the voltage on which is sufficient to turn it on, the phase voltages are compared, which allows to form initial synchronizing voltage that synchronizes digital (analogue) control systems for valve converters and three-phase adjustable rectifiers .

Thanks to a new set of essential features of the synchronization method for the control system of voltage converters and the introduced sequence of actions based on multilevel division of the half-wave of the phase voltage, due to which the circuit is simplified and synchronization accuracy is increased.

In the claimed device for synchronizing the control system of voltage converters, the technical result is achieved by the fact that in a known device for controlling a valve converter containing a low-power three-phase current source, the input of which is the input of the device, each of the six outputs of which is connected to the inputs of six positive current shapers and six pulse shapers controls, the outputs of which are connected to the load input, additionally, six phase voltage dividers are introduced, the input of each of which is connected to the first output of the corresponding shaper of the positive current direction, and the first outputs are connected to the first inputs of the optocouplers, while the second outputs of the first, second and third phase voltage dividers voltages are connected to the inputs of the first storage capacitor, the first, second and third outputs of which are connected to the second inputs of the first, second and third optocouplers, respectively, and the second outputs of the fourth, fifth and sixth phase voltage dividers are connected to the inputs of the second storage capacitor, the first, second and third outputs of which are connected to the second inputs of the fourth, fifth and sixth optocouplers, respectively, and the outputs of all optocouplers are connected to the inputs of the corresponding match elements, the outputs of which are connected to the first inputs of the respective rectangular pulse shapers , the outputs of which are connected to the inputs of the respective control pulse shapers, and the second inputs to the corresponding controller outputs, the first group of inputs of which is connected to the second outputs of the positive current direction shapers, and the second input is connected to the load output.

Thanks to a new set of essential features of the device for synchronizing control systems of voltage converters, the device is simplified, the elimination of winding elements (peak transformers) and the reliability of the proposed device is increased due to the operation of phase voltage dividers, rectification of the phase voltage and the inclusion of an optocoupler that turns on the coincidence elements that generate the signal rectangular shape, in the shaper of rectangular pulses, highlighting the moment of formation of control pulses generated in the shaper of control pulses and the controller that generates the shift of rectangular pulses.

The essence of the proposed method and device for synchronizing the voltage converter control system is to generate the initial synchronizing voltage as a result of two-level division of the half-wave of the phase voltage and compare them, which synchronizes digital (analogue) control systems for valve converters and three-phase adjustable rectifiers.

The claimed method of synchronization of control systems of voltage converters and the device for its implementation are illustrated by drawings, which show:

fig. 1 is a block diagram of a synchronization device for a voltage converter control system that implements a method for synchronizing a voltage converter control system;

fig. 2 - an algorithm that implements a method for synchronizing the control system of voltage converters;

fig. 3 - schematic diagram of the device for synchronizing the control system of voltage converters (power part of the device circuit);

fig. 4 - algorithm that implements the operation of the synchronization device of the control system of voltage converters;

fig. 5 - timing diagrams of the operation of synchronization of the control system of voltage converters.

The implementation of the claimed method for synchronizing the voltage converter control system shown in FIG. 1 is explained by the algorithm shown in FIG. 2:

in step 1 , a clock is generated by comparing the filtered clock voltage with a reference voltage;

in step 2 , the half-wave of the phase voltage is compared to the natural switching voltage;

in step 3 , the turn-on voltage of the galvanically isolated electronic element is compared with the rectified phase voltage; moreover, if the voltage ratings match, the transition to step 4 is carried out, and if they do not match, they return to step 2, comparing the half-wave of the phase voltage to the natural switching voltage;

in step 4 , if the rectified phase voltage corresponds to the turn-on voltage of the galvanically isolated electronic element, the initial synchronizing voltage is formed.

The described method, in relation to the synchronization devices of the voltage converter control system, implemented, for example, in a three-phase adjustable rectifier, can be executed using the synchronization device of the voltage converter control system shown in FIG. thirteen.

The claimed synchronization device for the control system of voltage converters, shown in Fig. 1, 3, contains a low-power three-phase current source (1), the input of which is the input of the device, each of the six outputs of which is connected to the inputs of six shapers of the positive current direction (2.1 ... 2.6) and six shapers of control pulses (8.1 ... 8.6), the outputs of which connected to the load input (10), six phase voltage dividers (3.1 ... 3.6), the input of each of which is connected to the first output of the corresponding shaper of the positive current direction (2.1 ... 2.6, each of the six semiconductor diodes, indicated in Fig. 3, as D1 -D6), and the first outputs are connected to the first inputs of the optocouplers (5.1 ... 5.6), while the second outputs of the first, second and third phase voltage dividers (3.1 ... 3.3) are connected to the inputs of the first storage capacitor (4.1), the first, second and third the outputs of which are connected to the second inputs of the first, second and third optocouplers (5.1 ... 5.3), respectively, and the second outputs of the fourth, fifth and sixth phase voltage dividers (3.4 ... 3.6) are connected to the inputs of the second storage capacitor (4.2), each of the three outputs of which is connected to the second inputs of the fourth, fifth and sixth optocouplers (5.4 ... 5.6), respectively, and the outputs of all optocouplers (5.1 ... 5.6) are connected to the inputs of the corresponding matching elements (6.1 ... 6.6), the outputs of which are connected to the first inputs of the corresponding rectangular pulse shapers (7.1 ... 7.6), the outputs of which are connected to the inputs of the corresponding control pulse shapers (8.1 ... 8.6), and the second inputs to the corresponding controller outputs (9), the first group the inputs of which is connected to the second outputs of the formers of the positive current direction (2.1 ... 2.6), and the second input is connected to the load output (10).

A low-power three-phase source 1 is designed to power the load 10.

Positive current shapers 2.1…2.6 are designed for unipolar voltage supply to phase voltage dividers. A variant of constructing positive current shapers 2.1…2.6 (semiconductor diodes) is known and described in [1].

Phase voltage dividers 3.1 ... 3.6 are designed to rectify the phase voltage and turn on the optocoupler (optocoupler).

Storage capacitors 4.1 and 4.2 are designed to form the level of phase voltages when they are equal in positive and negative half-cycles, which corresponds to the natural switching point of the power elements of the circuit.

Optocouplers 5.1 ... 5.6 are designed to include other elements of the device circuit.

Coincidence elements 6.1 ... 6.6 are designed to generate a rectangular signal in the shapers of rectangular pulses 7.1 ... 7.6. The variant of construction of elements of coincidence 6.1…6.6 is known and described in [1].

The shaper of rectangular pulses 7.1 ... 7.6, for example, a multivibrator circuit designed to detect the moment of formation of rectangular pulses.

Control pulse shaper 8.1 ... 8.6 - amplifying elements, drivers designed to generate control pulses. A variant of constructing a control pulse shaper 8.1…8.6 is known and described in [1].

The controller 9 is designed to form a shift of rectangular pulses. The option of constructing the controller 9 is known and described in [2-4].

Load 10 - any load (active, reactive).

The claimed synchronization device for the control system of voltage converters operates according to the following algorithm (see Fig. 4):

1) after the implementation of a unipolar voltage supply of a three-phase current (time diagram 1), obtained from a low-power three-phase current source, power is supplied to the phase voltage dividers (active resistances of direct and variable ratings), the form of the output voltage on which is shown in Fig. 5 (timing chart 2);

2) the phase voltage is rectified and the optocoupler is turned on (see Fig. 5, timing diagram 3);

, см. фиг. 5, временные диаграммы 4-9);3) rectangular signals are formed with the identification of the moment of their formation (implementation of a shift of rectangular signals, for example, by an angle

, see FIG. 5, timing charts 4-9);

4) control pulses are formed (see Fig. 5, timing diagrams 10-15).

, будет иметь вид, как показано на фиг. 5 (диаграмма 16).Thus, the shape of the output voltage of the rectifier, corrected by control pulses, for example, when the signals are shifted by an angle α=0 and α=

, will be as shown in Fig. 5 (diagram 16).

The voltage of the first phase (Fig. 5, the first voltage diagram) is rectified by the diode D1 (Fig. 3) and is divided by resistors R1, R2, R3. The voltage across capacitor C1 and resistor R3 is estimated from the expression:

,

,

and on the capacitor C2 according to the same formula, but with the opposite sign. Optocouplers A1…A6 LEDs are turned on by a voltage drop of 2…3 V across resistors R2 at the moment of equal voltage across the capacitors, which corresponds to the natural switching voltage of the power elements of the rectifier.

Turning on the LEDs initiates the operation of transistors optocouplers A1 ... A6, diodes D7, D8 implement the formation of rectangular pulses (see Fig. 5, timing diagrams 4-9) at the time of natural switching.

To change the moment of turning on the power elements of the converter, the rectangular pulse shaper 7.1 ... 7.6 (Fig. 1) (for example, a waiting multivibrator) can change the moment the formation of rectangular pulses starts according to the signal from the controller 9.

Thus, the claimed method and device for synchronizing the control system of voltage converters have a significant positive effect, which consists in increasing the reliability of the proposed device, the accuracy of regulating the output voltage of the converter and the maximum reduction (elimination) of winding elements (transformers, installations).

Literature

1. Titze U., Shenk K. Semiconductor circuitry. 12th ed. T. I, T. II: Per. with him. - M.: DMK Press, 2008. - 832 p.: ill.

2. Single-chip microcomputers. Directory. M.: MIKAP, 1994, - 400 p. : ill.

3. Shilo V.L. Popular CMOS Chips: A Handbook. - M.: Hot line - Telecom, 2001. - 112 p.

4. Mikushin A.V., Sazhnev A.M., Sedinin V.I. Digital devices and microprocessors. - St. Petersburg: BHV-Petersburg, 2010. - 832 p.

Claims (2)

1. The method of synchronizing the control system of voltage converters, which consists in the fact that sync pulses are generated by comparing the filtered synchronizing voltage with the reference voltage, the initial synchronizing voltage is calculated by dividing the phase voltages, characterized in that the half-wave of the phase voltage is divided into two levels, at the first of in which the half-wave of the phase voltage is compared with the voltage of natural switching of the converter circuit, and at the second level the rectified phase voltage is compared with the turn-on voltage of a galvanically isolated electronic element, the voltage on which is sufficient to turn it on, the phase voltages are compared, which makes it possible to form the initial synchronizing voltage that synchronizes digital or analog control systems for valve converters and three-phase adjustable rectifiers. 2. A device for synchronizing the control system of voltage converters, containing a low-power three-phase current source, the input of which is the input of the device, each of the six outputs of which is connected to the inputs of six shapers of the positive current direction, and six shapers of control pulses, the outputs of which are connected to the load input, characterized in that that six phase voltage dividers are additionally introduced, the input of each of which is connected to the first output of the corresponding shaper of the positive current direction, and the first outputs are connected to the first inputs of optocouplers, while the second outputs of the first, second and third phase voltage dividers are connected to the inputs of the first storage capacitor , the first, second and third outputs of which are connected to the second inputs of the first, second and third optocouplers, respectively, and the second outputs of the fourth, fifth and sixth phase voltage dividers are connected to the inputs of the second storage capacitor, the first, the second and third outputs of which are connected to the second inputs of the fourth, fifth and sixth optocouplers, respectively, and the outputs of all optocouplers are connected to the inputs of the corresponding match elements, the outputs of which are connected to the first inputs of the respective rectangular pulse shapers, the outputs of which are connected to the inputs of the respective control pulse shapers, and the second inputs - with the corresponding outputs of the controller, the first group of inputs of which is connected to the second outputs of the shapers of the positive current direction, and the second input is connected to the load output.

Images