RU2513547C1 - Static reversible converter for power supply of alternating and direct-current consumers - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention is related to reversible converters designed for power supply of alternating and direct-current consumers and the system contains the first input/output port at the side of connected accumulator battery and the second input/output port at the side of alternating-current supply mains. In inverter mode direct current is supplied from the accumulator battery to the first port while alternating current is outputted from the second port. In rectifier mode input alternating current is supplied to the second port while direct current is outputted from the first port. Between the ports there are in-series interconnected high-frequency link and a link of industrial frequency self-commutated inverter. Operation of the links is controlled by the control system. The high-frequency link is made as a combined scheme of resonance inverters and voltage inverters connected in parallel by their inputs and in-series by their outputs; while in rectifier mode is works as a combined scheme of voltage inverters and rectifiers. In inverter mode all invertors but one are non-regulated. One inverter is a regulated one. Non-regulated inverters create reference output voltage (minimum required). The regulated inverter shapes additional voltage added to the reference one so that output voltage could have the required value. In the rectifier mode wiring scheme of the reversible converter operates to generate charge current for accumulator batteries.

EFFECT: development of voltage converters designed to supply power to alternating- and direct-current consumers.

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Description

Technical field

The invention relates to the field of electrical engineering, in particular to voltage converters designed to power consumers of alternating and direct current.

An uninterruptible power supply device is known (RF Patent No. 2221320), which contains a network rectifier connected to an industrial AC power supply with AC leads, and to DC input terminals of a charge-buffer converter, DC output terminals of which are connected to a backup battery and inputs of DC / DC voltage converters. The disadvantage of this uninterruptible power supply device is that it does not provide the possibility of recovering the energy of the battery in a supply industrial AC network. In addition, the composition of this power supply device is redundant, since the battery charge is provided by a separate converter, and two inverting channels (main and auxiliary inverter) are used as part of the output DC-DC voltage converters, one of which works through a network rectifier only from an industrial network, and the second only from batteries.

A closer analogue is the technical solution protected by US patent No. 6160722. The claimed reversible converter has three input / output ports of power circuits: the main AC network, a DC source for connecting the battery and a port for connecting critical AC consumers. During normal operation from the main network, the alternating current is rectified, and then the inverter is converted to high-frequency alternating voltage, which is then fed to a high-frequency double-winding transformer and then, after rectification in the reversing converter, is supplied to the battery charge. At the same time, in this mode, responsible AC consumers are supplied from DC buses through a second inverter. In emergency mode, when the main network is interrupted, the responsible AC consumers are supplied with power from the battery through another high-frequency inverter, the aforementioned double-winding transformer, a reversing converter operating in this case as a rectifier and through the aforementioned first inverter. The disadvantage of the converter is the low efficiency of energy conversion and large losses, especially with a high power converter.

The minimization of the mass-dimensional parameters of the converter is carried out according to the invention according to the patent of the Russian Federation 2426215, selected as a prototype. According to the prototype, the uninterruptible power supply is made in the form of a reversible converter with an intermediate link of high frequency and ports for connecting a DC source and consumers. The reversible converter is provided with two input-output ports of power circuits, one of which is made in the form of a port for DC clamps with a battery connected to it at the input, and which is an input port for operation in inverter mode, and the other port is made in the form of clamps for AC current and is the output port in the inverter and the input in the rectifier operation modes. For electrical communication between the DC and AC clamps of the indicated ports through the circuit breakers, two links are connected in series, interconnected, one of which is a high frequency link, and the other is a link of an autonomous industrial frequency inverter, while the links are equipped with drivers for controlling power modules. Both links are used with controls in the inverter and rectifier modes. Moreover, in the rectifier mode and during normal operation of the AC network, responsible consumers are connected directly to the main AC network through a circuit breaker. At the same time, due to control means, a reversible converter provides the generation of controlled reactive power into an alternating current network, to which a voltage sensor with a voltage regulator is connected. The prototype operates in two main modes - inverter and rectifier, so named with some degree of conventionality:

a) in the inverter mode, the responsible consumers of alternating current receive power from the batteries through a reversible converter, b) in the rectifier mode, consumers of alternating current receive power from the alternating current network, for example, from a synchronous generator, and the battery is charged and the consumers of direct current are supplied through the reversible converter , i.e. a reversible converter transmits electricity in the opposite direction.

The high-frequency link contains two standard transistor-diode modules connected from the side of the primary and secondary windings of the transformer. Each of them works either in inverter mode, when all their elements are used, or in the rectifier mode, when only reverse diodes are used, and transistors do not open. In the inverter mode, the module connected to the primary winding of the transformer from the DC source side operates in the inverter mode, and the module included on the opposite side of the transformer operates in the rectifier mode. In the rectifier mode of operation of a reversible converter, the functions of the modules are reversed.

The link of a stand-alone inverter of industrial frequency, connected with its DC clamps to the DC clamps of the high-frequency link and the AC clamps through the current sensor to the clamps of the AC port, is made on the basis of one and several parallel transistor-diode modules and an LC filter low frequencies. This link is also made reversible. In the inverter mode, it operates in the autonomous inverter mode, in the rectifier mode it performs the function of a rectifier on the same standard module, the transistors and reverse diodes of which are connected according to the 3-phase bridge circuit, and its reverse diodes allow this function to be performed. Using transistors controlled by the sinusoidal PWM method, it is possible to regulate the flow of active and reactive power into the network or from the main AC network.

The disadvantages of this reversible converter include significant losses in the circuits, as well as low voltage stabilization of the DC link with a wide change in voltage at the input of the DC port.

The aim of the invention is to eliminate the disadvantages of the prototype, namely increasing the efficiency by reducing losses and improving the stabilization of the output voltage with a wide change in voltage at the input of the high frequency link.

Disclosure of the invention.

This goal is achieved by performing the high-frequency link of a static reversible converter in the form of a combined circuit of resonant inverters and voltage inverters connected in parallel to the input and sequentially in the inverter mode, and in the rectifier mode as a combined circuit of voltage inverters and rectifiers.

For inverter mode, all but one inverter is unregulated, and one inverter is adjustable. Unregulated inverters create a reference (minimum required) output voltage. The adjustable inverter generates additional voltage added to the reference in order to bring the output voltage of the converter to the required value (in accordance with the needs of AC consumers).

In the rectifier mode, the electrical circuit of the reversible converter works to generate the charge current of the batteries.

According to the invention, the static reversible converter (hereinafter referred to as the converter) for supplying AC and DC consumers contains a first “input output” port on the DC side with a battery connected to it and a second “input-output” port on the AC side. In the inverter operation mode of the converter, DC power is supplied to the first port, and AC output is removed from the second port, and in rectifier mode, AC input power is supplied to the second port, and DC output is removed from the first port. For the electrical communication of the ports between them, a high-frequency link and a link of an autonomous inverter of industrial frequency are connected in series, and both links operate in inverter and rectifier modes using a control system. The high-frequency link is made on the basis of single-phase bridge circuits of inverters associated with the control system. The AC output voltage is generated using three-phase bridge circuits with output LC filters. The high-frequency link is made in the form of a combined circuit of resonant inverters and voltage inverters connected in parallel at the input of the converter and sequentially in output for operation in the inverter mode, and in the form of a combined circuit of voltage inverters and rectifiers for operation in the rectifier mode. Such a connection of inverters provides stabilization of the AC link voltage with a wide change in the input voltage at the input of the first port.

More specifically, the high-frequency link can be made of three inverter-rectifier modules, of which two inverters are unregulated and one adjustable in the inverter mode, and two modules are adjustable in the rectifier mode, and one operates in key mode.

As an option, the high-frequency link also consists of three inverter-rectifier modules, of which, when operating in the inverter mode, two inverters are unregulated and one adjustable, connected to the rectifier on the diodes, and in the rectifier mode, two inverters are adjustable, and the rectifier on the diodes shunts the semiconductor switch.

The control system of the inverters of the high frequency link can be performed without a power regulator.

Thus, the invention allows to increase the efficiency of a reversible converter due to the rational use of unregulated and adjustable high-frequency inverters and to stabilize the output voltage of AC consumers in a wide range of voltage changes on the batteries. The use of simplified (without transistors) bridge circuits of some inverters provides optimization of weight and size indicators.

List of graphic figures

Figure 1. Static reversible converter circuit

Figure 2. Scheme of a static reversible converter (simplified version)

The implementation of the invention

Fig. 1 shows a diagram of a static reversible converter having two ports of input-output power circuits: a direct current port 1, to which an electric energy storage device is connected - an accumulator battery 2 (and possible direct current consumers) and an industrial frequency port 3 to which connect responsible AC consumers. The static reversible converter contains a high-frequency link 4 and an industrial frequency inverter 5. The static reversible converter operates in two modes: invertor, when DC power from the battery 2 is supplied to port 1, and the AC output is removed from port 3 and rectifier when the power AC power is supplied to port 3, and the DC output is removed from port 1.

Each link of the high frequency 4 contains a transformer 6, performing the function of galvanic isolation. Resonant inverters (standard transistor-diode modules of type IGBT) 7, 8 and non-resonant - 9, connected to it from the side of the primary winding, voltage inverters (similar to IGBT modules) 10, 11, 12, each of which works either in inverter mode of the module, when all the elements of the module are used transistors 13 and diodes 14, or in the rectifier mode, when only reverse diodes 14 are used, and the transistors do not open. Resonant inverters 7, 8 and non-resonant 9 are connected to port 1 in parallel, and voltage inverters 10, 11, 12 are connected in series. The operation of the inverters and switching between the operating modes is provided by the control system 15. As transformers 6, Payton planar transformers can be used, which reduce the weight, dimensions and ohmic losses. In the specific case, when the high-frequency link consists of three inverter-rectifier modules, in the inverter mode, the inverters 8 and 9 are unregulated and the inverter 7 is adjustable, and in the rectifier mode, two inverters 10, 11 are adjustable, and the inverter 12 is in key mode . Inverters 10, 11, 12 are connected in series and have an LC filter at the output, consisting of a capacitor 16 and a reactor 17, connected to the input terminals of the industrial frequency inverter 5.

The industrial frequency inverter 5 is made according to a three-phase bridge circuit based on one or more IGBT transistor-diode modules connected in parallel. It is also made reversible, i.e. It operates in inverter and rectifier modes by commands from the control system 15. Transistors and reverse diodes of the industrial frequency inverter 5 are connected according to a three-phase bridge circuit, and transistors controlled by the sinusoidal PWM method allow controlling the flow of active and reactive power. An LC filter 18 is connected between the output of the industrial frequency inverter 5 and the input-output port 3. The operation of inverters 7 and 8 in the resonant mode is provided by the capacitors 19, 20.

In a simplified version of the static reversible converter circuit (Figure 2), the high-frequency link 4 when operating in inverter mode also consists of three inverter-rectifier modules 7, 8, 9, of which two inverters in modules 7 and 8 are unregulated, and 9 is adjustable. However, in the rectifier mode, two inverters 10 and 11 are adjustable, and the third inverter 21 is designed as a bridge diode rectifier with a semiconductor switch 22 for shunting.

Static reversible Converter operates as follows.

Inverter mode

To implement the inverter mode of operation, the control system 15 sets the transistor-diode modules of the high frequency link 7, 8, 9 in the inverter mode, and the modules 10, 11, 12 rectifier mode of operation, and also sets the inverter mode of operation of the transistor-diode module of the inverter 5.

The DC voltage is supplied from the battery to the first input-output port 1 and from there to the high-frequency link 4. Inverters 7, 8, 9 of this link 4 convert the direct current to high-frequency alternating current. Unregulated inverters 7 and 8 provide a reference output voltage. AC voltage from inverters 7, 8, 9 through transformers 6 is supplied to inverters 10, 11, 12, which, working as a rectifier, convert alternating current into direct current. The adjustable inverter 9, by signals from the control system 15, receives an additional voltage, which is rectified and summed with the reference voltage from the inverters 7 and 8, providing stabilization of the output voltage when the battery voltage changes from 175 to 320 V, i.e. from the discharged to charged state of the battery 2. From the output of the high-frequency link 4, the rectified current through the LC filter (capacity 16, inductor 17) is supplied to the inverter 5, where it is converted into alternating current, which is supplied through the LC filter 18 to the input port -output "3 to ensure the operation of AC consumers.

Rectifier mode

To implement the rectifier operation mode of the static reversible converter, the control system 15 sets the inverters 7, 8, 9 of the high frequency link rectifier operation mode, and inverters 10, 11, 12 - the inverter mode. The rectifier operation mode for the inverter 5 is also set. The AC mains voltage is supplied to the input-output port 3 and from there to the inverter 5, operating in the rectifier mode and converting the alternating current to direct current. The direct current from the inverter 5 goes to the inverters 10, 11, 12, which, working in the inverter mode, convert it to high-frequency alternating current, which passes through the transformers 6 and is transmitted to the inverters 7, 8, 9, operating in the rectifier mode, from where the rectified direct current corresponding to the rated current of the battery charge is supplied to the input-output port 1.

Claims (4)

1. A static reversible converter for supplying AC and DC consumers, comprising a first “input output” port on the DC side with a battery connected to it and a second “input-output” port on the AC side, for connecting the ports between them the high-frequency link and the link of an autonomous inverter of industrial frequency, connected in series with each other, both links being used in the inverter and rectifier modes, while in the inverter operation mode In the case of a reversible converter, the DC input power is supplied to the first port, and the AC output is removed from the second port, and in the rectifier mode of the reversible converter, the AC input power is supplied to the second port, and the DC output is removed from the first port, and the high-frequency link is based on single-phase bridge circuits of inverters connected to the control system, and the output voltage of the alternating current is generated using three-phase bridge circuits with output LC filters,
characterized in that the high-frequency link is made for the inverter operation mode of the converter in the form of a combined circuit of resonant unregulated inverters and voltage inverters with rectifiers connected in parallel to the input and in series, and for the rectifier operation mode of the converter it is made in the form of a combined circuit of inverters input voltage and parallel rectifier output. 2. The static reversible Converter according to claim 1,
characterized in that the control system of the resonant inverters of the high frequency link is made without a voltage regulator 3. The static reversible Converter according to claim 1,
characterized in that the high-frequency link consists of three inverter-rectifier modules, of which, in the inverter mode, two inverters are unregulated and one adjustable, and in the rectifier mode, two inverters are adjustable, and one operates in key mode. 4. The static reversible Converter according to claim 1,
characterized in that the high frequency link consists of three inverter-rectifier modules, of which, when operating in the inverter mode, two inverters are unregulated and one adjustable, connected to the rectifier on the diodes, and in the rectifier mode, two inverters are adjustable, and the rectifier on the diodes shunts the semiconductor switch .

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