RU2421870C1 - Single-phase bridge self-commutated voltage inverter (versions) - Google Patents

Abstract

FIELD: electricity. ^ SUBSTANCE: as per the first version, clock-pulse generator with two antiphase outputs is introduced to the device; each of the above outputs is connected to starting inputs of the first and the second shapers of control pulses of the appropriate control channel with output pulses of various duration. As per the second version, in the device there is the possibility of controlling output voltage of single-phase bridge SVI at simplified scheme and improved reliability of the device as a whole owing to the second shapers of control pulses of each switch control channel with two inputs - starting and control ones, owing to introduction of clock-pulse generator with two antiphase outputs, each of which is connected to starting inputs of the first and the second shapers of the appropriate channel with output pulses of various duration, as well as owing to introduction of control element the output of which is connected to control input of the second shaper of each channel. ^ EFFECT: scheme is simplified and reliability of single-phase bridge SVI is improved. ^ 2 cl, 3 dwg

Description

The invention relates to electrical engineering, in particular to the field of converter technology for low frequency converters.

Known single-phase bridge autonomous voltage inverter (hereinafter AIN), made on the basis of two-operational lockable thyristor keys with pulse-width regulation and a DC link, made on a rectifier with a capacitor filter (Rudenko BC, Senko V.I., Chizhenko I.M. Fundamentals of transformative technology. ”/ M.: Higher School, 1980, p.237-240). The conversion of direct voltage to alternating current for supplying an active-inductive load of a given frequency occurs by switching diagonally arranged key pairs with pulses offset by 180 ° el. When switching the keys, the electromagnetic energy of the load is discharged into the capacitor bank of the DC voltage source. The capacity of the capacitor bank C reaches a large value, especially at low frequencies f and high currents AIN:

,

,

Where:

I is the load current;

t≡1 / f is the current flow time through the capacitor bank;

ΔU is the permissible value of the overvoltage on the capacitors.

At a current of several hundred amperes and low frequencies f (less than 5 Hz), the capacitance of a capacitor bank can reach farads.

The closest in technical essence to the claimed solution and taken as a prototype is a single-phase bridge AIN, made on single-operation thyristor switches, with an active-inductive load and a two-channel control system SU (Rozanov Yu.K. "Fundamentals of power electronics". / M.: Energoatomizdat 1992, p. 235-237). The operation of the device is based on pulse-width regulation of switches VS ₁ -VS ₄ , which are bridged by reverse diodes VD ₁ -VD ₄ , and are connected at the AIN input to a constant voltage source U _d , which when powered by an AC network consists of a rectifier with a parallel capacitor . The pairs of thyristors VS ₁ , VS ₄ and VS ₃ , VS _{2 are} switched by antiphase pulses with a frequency f using auxiliary switching thyristors VS ₁ ′ -VS ₄ ′ and reactive elements С _к , L _к , which can be eliminated, for example, when fully used controlled thyristors and transistors.

The device also contains oscillators PG ₁ PG _2, FU-shifting control device ₁ Fu FU _4, a scaling-MDP switchgears _{1, 2} MDP, conditioners output pulse for thyristor keys PHI ₁ and PHI ₄ -FI ₁ '-FI ₄ ′.

The disadvantages of the prototype are:

- the need for a capacitor bank of large overall dimensions and with large capacitance values for dumping the reactive energy of the load when performing a constant voltage source U _d in the form of a rectifier;

- the complexity of the control system.

The technical result of the claimed options for a single-phase bridge AIN is to simplify the circuit and increase the reliability of the device by eliminating the capacitor in the DC voltage source and simplifying the control system.

The technical result according to the first embodiment of the device is achieved by the fact that in a single-phase bridge autonomous voltage inverter containing a rectifier, a bridge converter made on diodes and semiconductor switches, for example transistor, active-inductive load and a control system consisting of two identical key management channels containing the first and second control pulse shapers, the outputs of which are connected to the corresponding key inputs, a clock pulse generator with two with emergency outputs, each of which is connected to the triggering inputs of the formers of the corresponding channel, while the pause between the trailing edge of the pulse of shorter duration τ _{2 of the} second shaper of one channel and the leading edge of the pulse of longer duration τ _{1 of the} first shaper of the other channel is longer than the time the load current drops to zero.

The technical result of the second embodiment of the device is achieved by the fact that in a single-phase bridge autonomous voltage inverter containing a rectifier, a bridge converter made on diodes and semiconductor switches, for example transistor, active-inductive load and a control system consisting of two identical key management channels containing the first and second control pulse shapers, the outputs of which are connected to the corresponding key inputs, a clock pulse generator with two anti-clock pulses is introduced by phase outputs, each of which is connected to the triggering inputs of the shapers of the corresponding channel, the regulator, the output of which is connected to the additionally introduced control input of the second shaper of each channel, with a pause between the trailing edge of the pulse of shorter duration τ _{2 of the} second shaper of one channel and the leading edge of the pulse is larger the duration τ _{1 of the} first shaper of the other channel is longer than the time the load current drops to zero.

The essence of the claimed invention according to the first embodiment is that due to the introduction of a clock pulse generator with two antiphase outputs, each of which is connected to the triggering inputs of the first and second control pulse shapers of the corresponding key control channel with output pulses of various durations, the circuit is simplified and the reliability of a single-phase bridge is increased AIN.

The essence of the device according to the second embodiment is that, due to the implementation of the second drivers of the control pulses of each key control channel with two inputs - the trigger and the control, the introduction of a clock pulse generator with two out-of-phase outputs, each of which is connected to the trigger inputs of the first and second formers of the corresponding channel with output pulses of various durations, as well as the introduction of a regulatory body, the output of which is connected to the regulatory input of the second form For each channel is achieved the possibility of regulating the output voltage AIN single-phase bridge circuit while simplifying and improving the reliability of the device as a whole.

Figure 1 shows a diagram of the inventive single-phase bridge AIN according to the first embodiment, figure 2 is a diagram of the second embodiment, which adopted the following notation:

1 - rectifier;

U _d is the average value of the output voltage of the rectifier 1;

2 - bridge converter;

3, 4, 7, 8 - diodes;

5, 6, 9, 10 - transistor switches;

11 - active inductive load;

u, i - respectively, the voltage and current at the load 11;

12 - control system;

13 - a clock generator with two out-of-phase pulses outputs with a frequency f;

14, 15 - two identical key management channels 5, 6 and 9, 10;

16 - the first driver of control pulses FI1 duration τ ₁ ;

17 - the second driver of the control pulses FI2 duration τ ₂ ;

18 - regulatory body (only for the scheme according to the second option).

Figure 3 shows diagrams of the claimed devices, where the following notation:

chart a) - antiphase clock pulses TI1 and TI2 in channels 14, 15 at the outputs of the generator 13 with a frequency f of figure 1, 2;

diagram b) - AIN operation diagram:

u (t) is the voltage at the load;

I _m is the amplitude value of the load current;

diagram c) - current-conducting elements of the AIN;

diagram d) - diagrams of control pulses with durations of τ ₁ and τ ₂ received from pulse shapers 16, 17 of channel 14 and arriving at the corresponding keys 5, 10;

Δt is the delay ("dead" time lasting several microseconds), excluding the simultaneous operation of two keys (5, 6 and 9, 10) when they are switched and shorting rectifier 1 (Fig. 1, 2).

diagram e) - diagrams of control pulses with durations of τ ₁ and τ ₂ received from pulse shapers 16, 17 of the control channel 15 and received on the corresponding keys 9, 6.

The single-phase bridge AIN according to the first embodiment contains a rectifier 1, a bridge converter 2, consisting of diodes 3, 4 connected in parallel to the corresponding transistor switches 5, 6 and diodes 7, 8 connected to the transistor switches 9, 10, a circuit is connected between the indicated pairs of transistor switches active-inductive load 11. The indicated transistor keys are controlled by a control system 12 containing an out-of-phase clock pulse generator 13 with a frequency f and two identical control channels with keys 14, 15, each of which there are pulse shapers: 16 - the first driver of the control pulses FI1 of duration τ ₁ with a trigger input, 17 - the second driver of the pulse pulses of FI1 duration τ ₂ with a trigger input. The triggering inputs of the control pulse shapers 16, 17 are interconnected and connected respectively to the first and second outputs of the clock pulse generator 13, the outputs of the control pulse shapers 16, 17 in both control channels 14, 15 are connected to the control circuits of the corresponding transistor switches 5, 10, 9 , 6. Between the trailing edge of the pulse with a shorter duration τ _{2 of} one channel and the leading edge of the pulse with a longer duration τ _{1 of the} other channel, a pause Δτ _{0 is created} (Fig. 3), which is longer than the load current decay time t ₁ and to zero.

The operation of a single-phase bridge AIN according to the first embodiment is as follows.

, а транзисторные ключи 6 и 10 - импульсами меньшей длительности τ₂, вырабатываемыми каналами управления 14, 15. В результате по окончании импульсов с длительностью τ₂ транзисторные ключи 10 и 6 закрываются, и ток нагрузки замыкается соответственно через диод 7 и транзисторный ключ 5 в первый полупериод частоты f и через диод 3 и транзисторный ключ 9 во второй полупериод. В этом случае в диаграмме напряжения на нагрузке u(t) имеется пауза Δτ₀, определяющаяся временем спада тока до нуля t₁ и временем задержки Δt. Включение следующей пары транзисторных ключей происходит после задержки Δt (несколько микросекунд), исключающей одновременное включенное состояние транзисторных ключей 5, 6 или 9, 10, что могло бы привести к закорачиванию выпрямителя 1. Общая пауза в диаграмме напряжения нагрузки составляет:Management of transistor switches 5, 6, 9, 10 is carried out by pulses of different durations (figure 3). Transistor switches 5 and 9 are controlled by pulses

, and transistor switches 6 and 10 with pulses of shorter duration τ ₂ generated by control channels 14, 15. As a result, at the end of pulses with a duration τ _2, transistor switches 10 and 6 are closed, and the load current is closed via diode 7 and transistor switch 5 v, respectively the first half-cycle of frequency f and through the diode 3 and the transistor switch 9 in the second half-cycle. In this case, there is a pause Δτ ₀ in the voltage diagram at the load u (t), which is determined by the current decay time to zero t ₁ and the delay time Δt. The inclusion of the next pair of transistor switches occurs after a delay Δt (several microseconds), which excludes the simultaneous switching on of the state of the transistor switches 5, 6 or 9, 10, which could lead to shorting of the rectifier 1. The total pause in the load voltage diagram is:

Δτ ₀ = t ₁ + Δt,

Where:

t ₁ ≈4T _n with the exponential nature of the rise and fall of the current;

T _n - time constant of the active-inductive load 11 (figure 1).

The single-phase bridge AIN according to the second embodiment (Fig. 2) contains all the elements of the device according to the first embodiment and a regulating body 18. In each channel, the second driver of control pulses 17 in the AIN according to the second embodiment has two inputs - a trigger (as in Fig. 1) and a control . The regulatory body 18 is connected to the regulatory input of the driver of the control pulses 17 in each control channel and provides control of the duration τ _{2 of the} control pulse.

The operation of a single-phase bridge AIN according to the second option is carried out in the same way as according to the first, but the function of regulating the voltage at the active-inductive load, which is carried out by changing τ ₂ depending on the control signal U _p at the input of the regulatory body, is added.

The effective value of the output voltage AIN is determined by:

,

,

Where:

τ _2р is the pulse duration of FI2 in radians;

τ _2c is the pulse duration of FI2 in seconds;

f is the frequency in hertz.

The inventive devices have several advantages compared to the prototype. By simplifying the control system and eliminating the capacitor at the output of the rectifier of a single-phase bridge AIN when it is powered from an AC network, the circuit is simplified and the reliability of the devices is increased, and the introduction of a regulatory body allows you to adjust the output voltage of the AIN.

Claims (2)

1. A single-phase bridge autonomous voltage inverter containing a rectifier, a bridge converter made on diodes and semiconductor switches, for example, transistor, active-inductive load and a control system consisting of two identical key control channels containing the first and second control pulse shapers, outputs which are connected to the corresponding inputs of the keys, characterized in that a clock generator with two antiphase outputs, each of which is connected to Let an input of the corresponding channel, wherein the pause between the trailing edge of the pulse duration τ at ₂ second shaper of one channel and the front edge of a pulse of longer duration τ ₁ of the first shaper other channel longer load current decay to zero. 2. A single-phase bridge autonomous voltage inverter containing a rectifier, a bridge converter made on diodes and semiconductor switches, for example transistor, active-inductive load and a control system consisting of two identical key control channels containing the first and second control pulse generators, the outputs of which connected to the corresponding inputs of the keys, characterized in that a clock generator with two antiphase outputs, each of which is connected to to the lowering inputs of the formers of the corresponding channel, the regulator whose output is connected to the additionally introduced regulatory input of the second former of each channel, while the pause between the trailing edge of the pulse of shorter duration τ _{2 of the} second shaper of one channel and the leading edge of the pulse of longer duration τ _{1 of the} first shaper of the other channel is greater the time the load current drops to zero.

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