RU2717966C1 - Static voltage converter - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to electrical engineering and railway transport, in particular to conversion of DC voltage of contact network to adjustable current of excitation windings of traction electric motors and into stabilized DC voltage for own vehicles consumers. Static voltage converter comprises voltage inverter consisting of power switches connected in bridge circuit, high-voltage power transformer, primary winding of which is connected in diagonal of bridge, and secondary winding is connected to power rectifier and LC-filter connected to output of power rectifier. Each inverter power switch consists of n-number of in-series connected IGBT-modules. Each IGBT-module is connected to a snooping RCD circuit or a capacitor. Power high-voltage transformer has at least three output windings, each of which is connected to power rectifier, which is made controlled and consists of thyristors. Voltage inverter comprises an idle stroke throttle, which is connected to the diagonal of the bridge parallel to the primary winding of the power high-voltage transformer. Voltage inverter and power rectifiers are controlled by digital control controller.

EFFECT: increasing the maximum possible working voltage at the input and increasing the operating frequency of the converter, enlarging the range of load variation at the output of the converter during operation without dynamic losses for switching on power switches, as well as enabling implementation of n-number of independent adjustable output channels during operation from one voltage inverter.

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Description

The invention relates to the fields of electrical engineering and railway transport, in particular to the conversion of a direct voltage of a contact network into a regulated current of excitation windings of traction electric motors and into a stabilized DC voltage for own consumers of vehicles.

The prior art DC-DC Converter from the patent of the Russian Federation 2345473 with the publication date 01/27/2009. The converter contains a single-phase pulse inverter, the primary windings of isolation transformers are included in the diagonal of the inverter, the secondary windings of the transformers are connected to the bridge and an LC filter. In each voltage inverter, parallel to each transistor switch, damping circuits are additionally connected.

The disadvantages of this converter are the low conversion frequency, high switching losses at low loads.

The prior art knows the serial connection of power transistors in order to reduce the maximum voltage level on individual switches (pp. 441-444 "Stabilized transistor converters", B.C. Moin, NN Laptev, M., Energy, 1972).

The serial connection of IGBT modules of a lower voltage class is known for use in replacing IGBT modules of a higher voltage class (pp. 344-348 Andreas Volke, Michael Hornkamp. IGBT Modules. Technologies, Drivers and Application. Publisher: Infineon Technologies AG, Munich, 2012) .

The disadvantage of this technical solution is the complex correction scheme for switching time of IGBT modules, which increases the complexity and dimensions of the final device and reduces its reliability.

A known static converter designed to control the excitation winding current of traction motors and to generate an intermediate voltage of 600 V for supplying other energy consumers in the backup mode, which includes an inverter assembled according to the bridge circuit with composite IGBT transistors, a transformer and three rectifiers, two of which the voltage is converted from the inverter output to a voltage with a controlled current value for supplying the field windings and one uncontrolled rectifier to a voltage of 600 In (p. 187-188 “Electric locomotive 2ES6“ Sinara ”. Edited by V.V. Brekson, V. Pyshma, LLC“ Ural Locomotives ”, 2015).

The disadvantages of the static converter are the use of an uncontrolled rectifier for generating the output voltage, which degrades the output voltage parameters of 600 V, and there is no possibility of equalizing the voltage between the IGBT modules connected in series.

The closest technical solution to the claimed invention is a voltage converter, known from the patent of the Russian Federation 2145145 with a publication date of 27.01.2000. The converter contains keys connected by a bridge circuit, a power transformer, the primary winding of which is included in the diagonal of the bridge, a saturation inductor, a power rectifier, an LC filter. The output of the LC filter is connected to the load. Each power switch contains a power transistor, shunted by a reverse diode and capacitor.

The disadvantages of the prototype are the lack of the possibility of implementing n number of independent adjustable output channels of the converter and the limitation on the maximum input voltage of the converter due to the limited maximum operating voltage of single power switches.

The technical problems to be solved by the claimed invention is directed are to reduce the mass and overall dimensions of the converter and expand the functionality.

Technical results are:

- increase the maximum possible operating voltage at the input of the Converter;

- increase the operating frequency of the converter;

- expanding the range of changes in the load at the inverter output when operating without dynamic losses on the inclusion of power switches;

- the ability to implement n number of independent adjustable output channels when operating from a single voltage inverter.

The technical results of the claimed invention are achieved through the implementation of a static converter containing a voltage inverter, consisting of power switches connected in a bridge circuit, a high-voltage power transformer, the primary winding of which is included in the diagonal of the bridge, and the secondary winding is connected to the power rectifier and an LC filter connected to the output of the power rectifier. Each inverter power switch consists of n number of IGBT modules connected in series. A snubber RCD circuit or capacitor is connected to each IGBT module. The high-voltage power transformer has at least three output windings, each of which is connected to a power rectifier, which is made controllable and consists of thyristors. The voltage inverter contains an idle throttle included in the diagonal of the bridge parallel to the primary winding of the high-voltage power transformer. The voltage inverter and power rectifiers are controlled by a digital control controller.

The digital control controller may be configured to generate control signals for the voltage inverter and the controlled rectifiers, and may also be configured to obtain information about the output currents and the output voltage of the controlled rectifiers. A delay has been introduced in the digital control controller to turn on the thyristor of the corresponding polarity in controlled rectifiers after turning off the IGBT modules.

The static voltage converter is designed to operate on high-voltage direct current, in particular, on the voltage of the contact network of the range 2200-4000 V, using an external circuit for pre-charging input capacitors. The converter generates at its output a current of a given value through two independent channels for inductive load, in particular for the excitation windings of the traction electric motors of the electric locomotive, and a stabilized voltage galvanically isolated from the input of the converter, to power various consumers, including consumers of the electric locomotive's own needs.

The figure 1 presents a schematic diagram of a static voltage Converter:

1 - voltage inverter

2 - power key

3 - IGBT module

4 - snubber RCD chain

5 - capacitor

6 - power high-voltage transformer

7 - controlled rectifier channel current formation

8 - controlled rectifier channel voltage generation

9 - LC filter

10 - digital control controller

11 - an idle throttle.

The static voltage converter contains a voltage inverter 1 made of power switches 2 according to the bridge circuit, each power switch 2 consists of n number of IGBT modules 3 connected in series, and a snubber RCD circuit 4 or capacitor 5 connected in parallel to each IGBT module 3, in a diagonal the primary winding of the power high-voltage transformer 6 is turned on, the controlled thyristor rectifiers of the current-forming channel 7 are connected to the two secondary windings of the transformer 6, and the transformer is connected to the third secondary winding 6, a controlled thyristor rectifier of voltage source 8 is connected, an LC filter 9 is connected to the output of rectifier 8. A static voltage converter contains a digital control controller 10, which generates control signals for voltage inverter 1 and controlled rectifiers 7 and 8 and receives information about output currents and output voltage. Parallel to the primary winding of the power high-voltage transformer 6, an idle throttle 11 is connected.

The static converter operates as follows.

The input voltage supplied to the static converter is supplied to the input of the voltage inverter 1, which converts the constant input voltage into alternating voltage of a rectangular shape, supplied to the primary winding of the high-voltage power transformer 6 from two outputs of which (secondary windings) the alternating voltage is supplied to controlled rectifiers 7 which ensure its conversion to direct current of a given value, and from the third output of the power high-voltage transformer 6 AC voltage is supplied to a controlled rectifier 8, assembled according to a bridge circuit, at the output of which a DC voltage is generated, which is smoothed by an LC filter 9.

The digital control controller 10 alternately generates turn-on signals to two diagonally arranged power switches 2 of the voltage inverter 1, while the duration of the turn-on signals is fixed and amounts to half the working period, minus the pause between turn-on signals (protective interval) when all power switches 2 of the voltage inverter 1 closed. The controller 10 receives information about the magnitude of the output currents at the output of the controlled rectifiers 7, 8 and about the voltage at the output of the LC filter 9, on the basis of which it regulates, that is, the generation of thyristor turn-on signals in the controlled rectifiers 7, 8.

In the static converter, the digital control controller 10 is configured to generate control signals for the voltage inverter 1 and controlled rectifiers 7, 8, while the duty cycle of the alternating voltage supplied from the inverter 1 is fixed, and each of the output channels is regulated independently, which makes it possible to realize n numbers independent output channels when operating from a single voltage inverter by adding to the additional secondary windings of the power transformer controlled ryamiteley. Also, the digital control controller 10 is configured to obtain information about the output currents and the output voltage of the controlled rectifiers 7, 8, which makes these independent output channels adjustable. Depending on the need, additional controlled rectifiers can be made in the form of a current generation channel or, together with an LC filter, in the form of a voltage generation channel.

The use of a digital control controller 10 for controlling thyristor rectifiers in a static converter allows you to implement additional functionalities such as, for example, limiting the output current, output voltage, output power, or turning on / off a controlled rectifier at the output of a controlled rectifier.

To increase the maximum allowable operating voltage of the static converter, each power switch 2 of the voltage inverter 1 is made of IGBT modules 3 connected in series, the number of which is determined by this operating voltage.

To equalize the voltage between the IGBT modules 3 connected in series during the switching period, a snubber 4 or a capacitor 5 is connected in parallel to each IGBT module 3.

When you turn off the power switches 2 of one of the diagonal of the bridge, the current flowing through the primary winding of the transformer 6, during the pause, recharges the snubber capacitor 4 or capacitor 5, connected in parallel to the IGBT modules and, then, the opposite diodes are closed through the built-in IGBT modules 3 the diagonal of the bridge, before turning it on, back through the input of voltage inverter 1, thereby realizing the inclusion of IGBT modules 3 at zero voltage (ZVS mode). To recharge the capacitor in the snubbers 4 or the capacitor 5, before turning on the IGBT modules (ZVS mode), the digital control controller 10 introduced a delay to turn on the thyristor of the corresponding polarity in the controlled rectifiers 7, 8 after turning off the IGBT modules 3 in the power switches (after changing the voltage polarity on the transformer 5). In this case, the capacitor is recharged in the snubbers 4 or the capacitor 5 due to the energy stored in the inductance at the output of the controlled rectifiers 7, 8. To implement the ZVS mode in the voltage inverter 1 in the absence of a load current at the output of the controlled rectifiers 7, 8 (open circuit mode) an idle throttle 11 is introduced into the diagonal of the bridge parallel to the primary winding of the transformer 6. The use of an idle throttle in a static converter 11 allows you to expand the range of load changes at the output of the static reobrazovatelya dynamic operation without loss of power switches switch, i.e. to ensure ZVS operation in case of a small output current and the idle mode.

The use of voltage 1 in the inverter, designed to operate at a high input voltage, as a power switch of IGBT modules connected in series and implementing the ZVS mode allows increasing the working frequency of the static converter, thereby reducing the weight and dimensions of the power transformer and filter elements at the input and output of the converter .

Thus, the implementation of the invention with the totality of the claimed features in the formula allows to solve technical problems and provide the technical results indicated in the description of the invention.

Claims (4)

1. A static voltage converter containing a voltage inverter, consisting of power switches connected in a bridge circuit, a high-voltage power transformer, the primary winding of which is included in the diagonal of the bridge, and the secondary winding is connected to the power rectifier and an LC filter connected to the output of the power rectifier, characterized in that each power switch of the inverter consists of an n-number of series-connected IGBT modules; moreover, a snubber RCD circuit or capacitor is connected to each IGBT module, the high-voltage power transformer has at least three output windings, each of which is connected to the power rectifier, which is made controllable and consists of thyristors, while the voltage inverter contains an open circuit choke, included in the diagonal of the bridge parallel to the primary winding of the high-voltage power transformer, and the voltage inverter and power rectifiers are controlled by a digital controller and I. 2. The static converter according to claim 1, characterized in that the digital control controller is configured to generate control signals for the voltage inverter and controlled rectifiers. 3. The static converter according to claim 1, characterized in that the digital control controller is configured to obtain information about the output currents and the output voltage of the controlled rectifiers. 4. The static converter according to claim 1, characterized in that a delay is introduced in the digital control controller to turn on the thyristor of the corresponding polarity in the controlled rectifiers after turning off the IGBT modules.

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