Voltage converter built around combined circuit arrangement
 Power switch built around mis transistor / 2263393Power switch built around MIS transistor 11 incorporating transistors 1, 2 whose base-emitter junctions are shorted out by resistors 5, 6 and collector-emitter ones, by diodes 3, 4 in cut-off direction has collector of transistor 2 connected to gate of MIS transistor 11, emitters of transistors 1, 2, interconnected, and collector of transistor 1, connected to starting lead of secondary winding 9 of transformer 7, finishing lead of this winding being directly connected to source of MIS transistor 11. In addition, one more secondary winding 10 having lower transformation ratio than secondary winding 9 is newly introduced in transformer 7 and connected to bases of transistors 1, 2. |
 Force key on mis-transistor / 2262799Transformer 5 has additional winding, edge contacts of which are connected to bases of transistors 1 and 2, emitters of which are connected and through resistor 9 are connected to middle point of additional winding, and collector-emitter transfers are linked by diodes 3 and 4 in locking direction. Collector T 1 is connected to start of secondary winding TP 5, end of which is connected to source of MIS-transistor 10, gate of which is connected to collector T 2. |
 Force key built on mis-transistor / 2262187Device uses MIS-transistor 10, including transistors 1,2 between bases of which resistor 9 is connected, and base-emitter transfers are linked by diodes 3,4 in locking direction, collector 2 is connected to gate of MIS-transistor 10, emitters 1,2 are connected, and collector 1 is connected to start of primary winding 7 of transformer 5, end of which is directly connected to source of MIS-transistor 10. also, transistor 5 additionally includes secondary winding 8 with decreasing transformation coefficient relatively to secondary winding 7, connected serially to resistor 9 and bases of transistors 1,2. |
 Method for controlling four-quadrant converter / 2261519Proposed method includes alternate closure of input voltage supply through inductance coil and its opening throughout entire positive half-cycle of supply voltage until current attains sum of desired value and permissible deviation, as well as difference in desired value and permissible deviation, respectively, during each switching operation; closure of input voltage supply during entire negative half-cycle of supply voltage until current equals difference in desired value and permissible deviation, as well as opening of input voltage supply until current is brought to sum of mentioned values. Permissible current deviation is found from formula ΔI = Um/8π2mfL, where Um is peak value of supply voltage; L is inductance of converter input circuit; m is number of switching operations within half-cycle; f is supply voltage frequency. Proposed method provides for complete use of capacity of power semiconductor devices, maximal possible rate of switching operations, improved waveform of input current, and its maximal approach to quasi-sinusoidal waveform resulting in enhanced power factor and reduced load on supply mains. |
 Transistor generator for resonance-tuned loads / 2260899Proposed transistor generator has half-bridge inverter built around IGBT transistors controlled by half-bridge driver using standard circuit arrangement and provided with internal generator, external time-setting RC circuit, and output transformer; it also has optocoupler transistor, three additional resistors, capacitor, and current transformer. |
 Force key on mis-transistor / 2257668Transformer 5 is made with additional branches 13, 14 forming two additional windings relatively to edge outputs, while each branch 13 and 14 through resistor 11 and 12 is connected to transistor base 1 and 2, emitter of which is connected to edge output 8 and 9 of same additional winding. Collector-emitter links of transistor 1 and 2 are linked by diodes 3 and 4 in locking direction. Collector of transistor 1 is connected to latch, and collector 2 - to source of MIS transistor. |
 Dc-to-ac voltage converter / 2251203Proposed converter has two p-n-p transistors 1, 2 and two n-p-n ones 3, 4, all four transistors being interconnected in bridge circuit. Emitters of transistors 1 and 2 are interconnected and connected to one pole of power supply 5; emitters of transistors 3 and 4 are also interconnected and connected to other pole of power supply 5. Collectors of transistors 1 and 3 are connected to terminal A of primary winding AX of transformer 6 (shown in dash lines) and other terminal X of this winding is connected to common connection point of collectors of transistors 2 and 4. One of secondary windings of transformer 6, for instance a1x1, is connected through capacitor 7 between bases of transistors 3 and 4 whose emitters are directly interconnected, and load 8 is connected to secondary winding a2x2 of transformer 6. Resistor 9 is connected between bases of transistors 1 and 4, resistor 10, between bases of transistors 2 and 3. Circuit set up of diode 11 and resistor 12 is inserted between emitter and base of transistor 3 and similar circuit of resistor 13 and diode 14, between emitter and base of transistor 4. Feedback circuit set up of secondary winding a1x1 of transformer 6 and capacitor 7 can be also inserted between bases of other pair of transistors 1 and 2 whose emitters are also directly interconnected, that is it can be transferred from base circuit of transistors 3 and 4. In this case circuit set up of diode 11 and resistor 12, like that of diode 14 and resistor 13, will be, respectively, connected to emitter-base junction of transistors 1 and 2. Proposed design makes it possible to use both unsaturable and saturable transformers with primary winding not center-tapped. |
 High-frequency dc-to-ac transistor converter incorporating electronic protective gear / 2249295Proposed converter is built around off-line voltage inverter that has transistors 1 through 4, back-to-back diodes 5 through 8, transformer 9, and ac voltage component filter incorporating reactor 10, capacitor 11, additional reactor 12, short-circuiting switch 13, and diode 14, all connected at input of mentioned voltage inverter. Control unit 15 has clock generator 16, scaling device 17, control-current pulse shaper 18, and electrical decoupling device 19. Newly introduced in control unit are inhibit location with memory 20 and critical current sensor 21. With such design of control system generation of pulses driving gates of inverter transistors in conduction ceases upon arrival of logical 1 signal shaped by inhibit location and upon disconnection of clock generator, and input of mentioned voltage inverter is shorted out by short-circuiting switch for time equal to characteristic oscillation period of circuit set up by filter capacitor and additional reactor. Converter is characterized in reduced emergency cutoff transient time and also reduced maximal short-circuit current. |
 Current inverter / 2249294Proposed current inverter built in the form of single-phase bridge around transistors with series-connected diodes and transistor shunting diodes is provided with newly introduced series circuits of which one incorporates voltage limiter and two resistors, other circuit has voltage limiter, and third one, two resistors, two diodes, and two capacitors. Each series circuit shorts out single-phase bridge built around transistors and connected to input leads through filter chokes. Third series circuit is connected to collector and emitter groups of single-phase bridge transistor through fourth and fifth series circuits, each incorporating diode, resistor, and choke. In case of open circuit in induction heater thyristor is turned on to short out single-phase bridge through capacitor that limits input voltage of inverter in response to thyristor failure. Input voltage of inverter is limited by limiting voltage across first series circuit. |
 Current inverter / 2246170Proposed current inverter has single-phase bridge built around four transistors and connected to its input leads through filter chokes, as well as compensating capacitor shunting output leads of current inverter; ac leads of mentioned single-phase bridge are connected to output leads of current inverter through switching chokes; collector group of single-phase bridge is connected to emitter group through series circuit set up of capacitor, diode, and second capacitor; thyristor is connected in parallel opposition to diode; cathode of the latter is connected to collector group through series circuit set up of second diode, choke, and resistor; diode anode is connected to emitter group through series circuit set up of diode, second choke, and second resistor. |
 Device for automatic tuning of adjustable-gap arc-control reactor correction / 2266600Proposed device for automatic tuning of adjustable-gap arc-control reactor correction has motor control unit connected to correction maladjustment recording unit and to control input of mentioned arc-control reactor provided with motor for air gap adjustment. Motor control unit has first contactor control unit connected through first auxiliary contact to correction maladjustment recording unit, second contactor control coil connected through second auxiliary contact to correction maladjustment recording unit, and third contactor control coil. First and second power contacts are connected to control input of adjustable-gap arc-control reactor; third and fourth auxiliary contacts are connected to short-pulse shaper. Final relay is connected to short-pulse shaper and its contact is inserted in third control coil of contactor. Fifth and sixth auxiliary contacts are connected in series with first contactor control coil and with second contactor control coil, respectively. Motor control unit also has rectifier bridge connected through limiting resistor and third power contact to control input of mentioned reactor incorporating air gap adjusting motor. |
 Reactive power correcting device / 2256994Reactive power correcting device has traction transformer, electric-locomotive rectifying converter with traction motor connected thereto, two reactive-power sources, supply-mains mode sensor, and switching unit; newly introduced are also two switching members, each incorporating thyristor switch, voltage sensor built around thyristors, and thyristor-switch control pulse shaper, as well as two resistors; thyristor switches are connected in series with first and second reactive power sources and resistors are connected in parallel with capacitors of respective reactive-power sources. |
 Transistorized tree-phase reactive-current supply / 2254658Proposed device tat can be used to raise efficiency of electrical energy consumption due to relieving power supply mains of reactive currents has three-phase diode bridge connected to supply mains through three reactors; connected at dc output of this diode bridge through isolating diodes are three storage capacitors. Device also has bridge inverter built around six transistors connected through their outputs to ac input of diode bridge and three additional transistors connecting dc input of inverter to storage capacitors. Transistor control system functions to convert signals arriving from outputs of voltage sensors across load, load and supply mains current sensors, and to generate thyristor control signals so that source automatically generates correction currents equal to reactive currents consumed by load, and only resistive component of load currents is consumed from supply mains. |
 Three-phase reactive-power corrector / 2251192Proposed reactive-power corrector has three-phase transformer, three single-phase inverters with control systems, rectifier, three single-phase current transformers, potential transformer, three single-phase reactive-current sensors, three voltage sensors, three comparison gates, and load; in addition it is provided with newly introduced unit of off-line voltage inverters, active and reactive power computing unit, active and reactive power ac component computing unit, desired current computing unit, off-line voltage inverter control unit, and current transformers of off-line voltage inverters. |
 Single-phase instant-power passive component corrector / 2249896Proposed corrector uses circuit arrangement of single-phase voltage inverter in the form of transistor bridge incorporating inverted diodes with storage capacitor connected across two diagonally opposite dc terminals and two diagonally opposite ac terminals connected through choke to supply mains in parallel with load; choke has sectionalized coil, that is it is made of two sections with output lead in-between; corrector is provided with newly introduced switch built around two thyristors and used to connect one section of choke coil during discharge of storage capacitor and both sections during its charge. |
 Method and circuit arrangement for using polarized devices in operation on ac current / 2249285Polarized capacitors or electrochemical batteries are used in standard ac circuits as polarized electrical charge storage devices with new circuit pattern. In one of alternatives opposing-series configuration of first and second polarized devices is used in ac network to improve its operating conditions. At least one dc power supply is provided to keep polarized devices shifted in forward direction when ac signal arrives at them. This ac signal is applied to devices connected in series opposition to excite ac load. These devices are sufficiently shifted by at least one dc voltage supply so that they remain displaced in forward direction upon connection to ac signal. |
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Method and circuit arrangement for using polarized devices in operation on ac current / 2249285 Polarized capacitors or electrochemical batteries are used in standard ac circuits as polarized electrical charge storage devices with new circuit pattern. In one of alternatives opposing-series configuration of first and second polarized devices is used in ac network to improve its operating conditions. At least one dc power supply is provided to keep polarized devices shifted in forward direction when ac signal arrives at them. This ac signal is applied to devices connected in series opposition to excite ac load. These devices are sufficiently shifted by at least one dc voltage supply so that they remain displaced in forward direction upon connection to ac signal. |
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Single-phase instant-power passive component corrector / 2249896 Proposed corrector uses circuit arrangement of single-phase voltage inverter in the form of transistor bridge incorporating inverted diodes with storage capacitor connected across two diagonally opposite dc terminals and two diagonally opposite ac terminals connected through choke to supply mains in parallel with load; choke has sectionalized coil, that is it is made of two sections with output lead in-between; corrector is provided with newly introduced switch built around two thyristors and used to connect one section of choke coil during discharge of storage capacitor and both sections during its charge. |
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Three-phase reactive-power corrector / 2251192 Proposed reactive-power corrector has three-phase transformer, three single-phase inverters with control systems, rectifier, three single-phase current transformers, potential transformer, three single-phase reactive-current sensors, three voltage sensors, three comparison gates, and load; in addition it is provided with newly introduced unit of off-line voltage inverters, active and reactive power computing unit, active and reactive power ac component computing unit, desired current computing unit, off-line voltage inverter control unit, and current transformers of off-line voltage inverters. |
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Transistorized tree-phase reactive-current supply / 2254658 Proposed device tat can be used to raise efficiency of electrical energy consumption due to relieving power supply mains of reactive currents has three-phase diode bridge connected to supply mains through three reactors; connected at dc output of this diode bridge through isolating diodes are three storage capacitors. Device also has bridge inverter built around six transistors connected through their outputs to ac input of diode bridge and three additional transistors connecting dc input of inverter to storage capacitors. Transistor control system functions to convert signals arriving from outputs of voltage sensors across load, load and supply mains current sensors, and to generate thyristor control signals so that source automatically generates correction currents equal to reactive currents consumed by load, and only resistive component of load currents is consumed from supply mains. |
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Reactive power correcting device / 2256994 Reactive power correcting device has traction transformer, electric-locomotive rectifying converter with traction motor connected thereto, two reactive-power sources, supply-mains mode sensor, and switching unit; newly introduced are also two switching members, each incorporating thyristor switch, voltage sensor built around thyristors, and thyristor-switch control pulse shaper, as well as two resistors; thyristor switches are connected in series with first and second reactive power sources and resistors are connected in parallel with capacitors of respective reactive-power sources. |
FIELD: regulation and reactive power correction in power systems; inverters for high-voltage frequency-controlled electric drives.
SUBSTANCE: proposed converter is built around combined circuit arrangement incorporating three-phase bridge circuit of voltage inverter (with series-interconnected semiconductor devices of IGCT, IGBT, and other types) with one or more series-interconnected single-phase bridge voltage converters (whose semiconductor devices are not interconnected in series)connected to each of its phase outputs. All change-over operations are made in three-phase bridge circuit whose arms form valves with series-interconnected semiconductor devices and which forms output voltage base of converter at low frequency (such as that equal to supply mains frequency). Bridge arms incorporating series-interconnected semiconductor devices having different on/off delay times are changed over by means of switching circuits specially inserted in circuit.
EFFECT: enhanced reliability reduced power loss in building converter combined circuit, reduced dynamic loss in semiconductor devices.
3 cl, 9 dwg
The invention relates to a Converter equipment, namely, high voltage converters, requiring the use of a series connection of semiconductor managed devices, and is intended for device regulation and compensation of reactive power in power systems. This Converter can be used as an inverter in a high-voltage variable frequency drives.
Known to use devices for regulation and compensation of reactive power in power systems three-level pulse-width Converter [1]. This is the simplest configuration technical solution, but its implementation requires high-frequency switching. To implement such a Converter in the class higher voltages require the use of serial connections controlled semiconductor devices. Even with a slight variation in lag time off (turn off) and turn on (turn on) the series connected devices for equalizing voltages required dividing circuit considerable power, loss of energy which is much higher than the dynamic power losses in the device. Theoretically it is also possible to perform a selection of identical devices without dividing circuits, but in practice it does not sell. Schemes transformer addition when a voltage of several inverters are formed using a special intermediate transformers require additional costs.
Known converters for adjustable speed drive, made by a combined scheme [2], consisting of a three-phase duplex (forming two voltage levels: positive and negative) or three-level (forming three voltage levels: positive, negative, and zero) a basic voltage inverter, one or more series-connected single-phase bridge inverter circuits in each phase at the output of the basic inverter and control system all inverters pulse width method. This option is closest to the present invention. And two-tier and three-tier basic three-phase inverter is a voltage level that is several times higher than the voltage in single-phase bridge circuits, and forms the basis of a voltage close on the effective value, but poor form. The frequency of the switching three-phase inverter is much lower than the frequency of switching in single-phase bridge circuits. Single-phase bridge inverters form a Supplement to the base. The result is the summed signal of the desired shape. This is a good technical solution for the stresses of the order of 6-7 kV (as the decree is in [2]). To implement such a Converter in the class higher voltages require the use of a series connection of semiconductor devices and in this case, as in [1], to align the voltages required dividing circuit considerable power, loss of energy which is much higher than the dynamic power losses in the device.
You know the invention [3], giving a reduction of the dynamic losses of the transistors in the transistor inverter made in a bridge circuit, by introducing into each shoulder an additional chain, reducing the slew rate of the voltage on each of the transistors by reducing the slew rate of the discharge current of the capacitors. The use of the Converter with such chains in a two-level three-phase circuit is possible, but involves low frequency switching and, therefore, as the output voltage of the Converter is for tasks unsatisfactory. In three-phase three-level scheme proposed chain do not work.
The purpose of the present invention is to improve reliability and reduce power loss when building a combined circuit high voltage Converter that uses a serial connection of a semiconductor managed devices. Technical solution allows to apply the ü serial connection devices, in which there is variation in lag time off (turn off) and turn on (turn on).
The achievement of this goal in the voltage Converter, made by a combined scheme that includes basic three-phase bridge inverter voltage on the gates formed by series-connected controllable semiconductor devices in each arm of the bridge, two-, three - or-more-layered structure, and single-phase bridge voltage source inverters connected to each phase of the inverter output of the base in one or more series-connected AC current in each phase is provided by the introduction to each shoulder of the base of the inverter switching chains of series-connected capacitor and commutating diodes, and commutating reactors, connected in series with the gate of the shoulder, respectively, with side of the positive or negative bus of the basic inverter and/or phase of the output, and the switching diodes chains connected directly to the valve shoulder according to him about switching reactors. Introduced in the basic scheme of the inverter capacitors connected in parallel to the gates of the shoulders and separated from them switching diodes. Also in each phase of the basic inverter entered recuperating units engaged in rebuilding the energy switching in capacitors DC voltage. Recuperating blocks, the outputs are enabled between the DC bus of the basic inverter inputs respectively included between the positive bus, a negative bus or phase output and connection points of the capacitors and diodes of the switching chain. With the above construction of the scheme selected control algorithm, in accordance with the manipulated switch basic circuit at a low frequency comparable to the frequency of the network, which does not require fast switching. The formation of the monitored signal is placed on cascaded single-phase inverter bridges due to pulse width modulation in each bridge circuit, and a shift in the management of each of the single-phase bridges with higher frequency switching in possible, because the serial connection of semiconductor devices is not assumed.
To clarify the nature of the invention figa presents Converter block diagram for regulation and compensation of reactive power in the power grid, the basis of the output voltage which is formed by using a three-level three-phase bridge inverter;
on figb structural diagram of the phase three-level three-phase bridge inverter;
on FIGU shows the structural block diagram of the regenerative energy is AI, used in phases three-phase inverter;
on figa presents a structural diagram of the Converter, the basis of the output voltage which is formed by using a two-level three-phase bridge inverter;
on figb the block diagram of phase two-level three-phase bridge inverter;
on figv the block diagram of phase two-level three-phase bridge inverter with switching of the switching reactors at the midpoint of phase;
figure 3 shows a structure of a control system of the inverter;
figure 4 shows the waveforms of the voltages on the three series-connected IGCTs-thyristors (4500, 4000 a) when the switch-off delay of the two of them on 1 µs when the circuit switching circuits;
figure 5 shows waveforms explaining the operation principle of the proposed scheme.
Device and criteria for the selection of the type and quantity of the essential elements of the claimed technical solution in its static condition described in schemes 1 and 2.
Here is ways to build a three-phase inverter for three - and two-level scheme.
1. The structure of the transducer, the basis of the output voltage which is formed by using a three-level three-phase bridge inverter, presented at figa.
Three-level three-phase bridge inverter 1 consists of three is AZ (2, 3, 4) and condenser batteries (5, 6) to the middle (neutral) point 7. To phase the findings of the three-phase inverter (points 8, 9, 10) are connected serially connected single-phase bridge inverters (11(1)...11(n), 12(1)12...(n), 13(1)...13(n)). Contact tire combo transducer (points a, b, C) is connected to the mains (without a filter or with filter - depending on the requirements of the application).
To ensure switching valves 14, 15, 16, 17 (figb - phase 2) phase bridge inverter 2, 3, 4 valves formed by the serial connection is fully controlled semiconductor devices (with reverse diode protection circuit), the circuit of the phase inverter is enabled condenser battery (figb: 18 between points 20 and 21; 19 between the points 22 and 23) to limit the rate of change of voltage at the gates (hereinafter referred to dU/dt). The value of the capacitance of capacitor Bank is selected based restrictions dU/dt at an acceptable level, based on the requirement of not exceeding the maximum permissible operating voltage in semiconductor devices considering the variation of their time on/off (when you turn off the "fast"and when you enable the "slow" devices in the absence of additional measures are under full tension). To ensure switching valves without surge of current through the reverse diodes (14(1)...14(n2), 15(1)...15(2). 16(1)...16(n2), 17(1)...17(n2)) and shunt (24, 25) diodes to reduce the level of overvoltage on the valves due to the inductance of the mounting of the filter capacitor battery DC voltage (figa: 5 and 6), as well as to limit the short circuit current at the breakdown diagram of the phase inverter is enabled commutating reactors (figb: 26 between points 28 and 29; 27 between points 30 and 8; 31 between points 8 and 32; 33 between points 34 and 35 that limits the rate of change of current (di/dt) through the valves. The inductor commutating reactor is selected from the calculation of the limit di/dt at an acceptable level, based on the requirement of not exceeding the maximum permissible repetitive current through the semiconductor devices. To bring the energy of the reactor after the switching valve and the circuit includes a switching diodes (figb: 36 between points 20 and 29; 37 between the points 21 and 27; 38 between points 22 and 33; 39 between the points 23 and 34) and recuperating converters (figb: 40 between the points 29 and 20, 41 between points 21 and 22 and 42 between the points 23 and 35)engaged in the energy recovery switching back to the capacitor DC voltage 5 and 6 (except for the losses in the converters).
2. The structure of the transducer, the basis of the output voltage which is formed by using a two-level three-phase bridge inverter, presented at figa
Duhur is wavy three-phase bridge inverter 1 consists of three phases (2, 3, 4) and condenser battery 43. To phase the findings of the three-phase inverter (points 8, 9, 10) are connected serially connected single-phase bridge inverters 12(1)12...(n), 13(1)...13(n)14(1)...14(n)). Contact tire combo transducer (points a, b, C) connected to the mains (without a filter or with filter - depending on the requirements of the application).
To ensure switching valves 44, 45 (figb) phase bridge inverter 2, 3, 4 valves formed by the serial connection is fully controlled semiconductor devices (with reverse diode protection circuit), the circuit of the phase inverter is enabled condenser battery (figa: 46 between the points 48 and 8; 47 between points 8 and 49) to limit dU/dt on the valves. The value of the capacitance of capacitor Bank is selected based restrictions dU/dt at an acceptable level, based on the requirement of not exceeding the maximum permissible operating voltage in semiconductor devices considering the variation of their time on/off.
To ensure switching valves without surge of current through the reverse (44(1)...44(n3), 45(1)...45(n3),) diodes to reduce the level of overvoltage on the valves due to the inductance of the mounting of the filter capacitor Bank DC voltage (figa: 43), as well as to limit the short circuit current at the breakdown in scheme f the s inverter included commutating reactors (figb: 50 between points 29 and 51; 53 between points 52 and 35), limiting the rate of change of current (di/dt) through the valves. The inductor commutating reactor is selected from the calculation of the limit di/dt at an acceptable level, based on the requirement of not exceeding the maximum permissible repetitive current through the semiconductor devices. To bring the energy of the reactor after the switching valve and the circuit includes a switching diodes (figb: 54 between points 48 and 51; 55 between points 52 and 49) and recuperating converters (figb: 56 between the points 29 and 48, 57 between the points 49 and 35)engaged in the energy recovery switching back to the condenser battery DC voltage 43 (except for losses in the converters).
By analogy with [3], commutating reactors can be included in the midpoint phase (pigv).
The principle of the proposed Converter will be shown by the example of his variant version with three-phase bridge three-level inverter as a basic inverter.
The control system (figure 3) using blocks PWM modulator generates in sequence the pulses of the control valves of all inverters. This three-level three-phase bridge inverter generates between the middle point 7 and phase conclusions the three-phase inverter (points 8, 9, 10) one of three voltage levels (positive, tricatel is Noah and zero) (U3 figure 5). Switching valves are performed by system management in accordance with the adopted algorithm. The control system has several control loops, among which are the two global path:
- peak value of a current through the reactor output filter (signal i, figure 3);
- peak value of a voltage output (transformer bus bar voltage connection output filter capacitors) - (signal and figure 3).
In addition, for testing of fast processes organized local loops on the instantaneous values of current and voltage from the output of the filter, as well as several local loops for current and voltage with capacitor DC voltage basic inverter and single-phase bridges cascade inverter.
In General, the control system is based on the principle of maintaining the setpoint(REFO figure 5) tracked its output signal. Basic three-phase bridge inverter forms the basis (U3 figure 5) the output voltage of the inverter with low switching frequency (S13...S123a, b, c) in figure 3). The difference between job
and the basis of U3 is formed of a single-phase bridge inverter by pulse width modulation (PWM). The management of each of the single the EIT bridge inverters ((S1 0...S40a, b, c), (S11...S4la, b, c), (S12...S42a, b, c) in figure 3) is provided with a phase shift relative to each other, thereby increasing the resulting frequency output voltage ripple.
The circuit includes recuperating converters, providing energy return commutation capacitor in the battery DC voltage 5, 6 (except for the losses in the converters). One of the possible options recuperating Converter explains figv. When you turn off the control valve (for example 14) energy commutating reactor (for example 26) through the switching diodes (e.g. 36) charges the capacitor 58. The average DC voltage of the capacitor 58 is converted by the inverter 59 AC voltage of high frequency. The transformer 60 increases to the voltage level on the capacitor battery 5, 6 a DC link and then after rectification by the rectifier 61 the voltage applied to the capacitor battery. Thus reactive energy switching from the reactor is returned in the accumulation capacitor battery.
In General, when the regulation of three-phase three-level inverter (including the possibility of multiple switches of the same valve for half-life) depending on the sign of the generated output voltages in Zmeiny the following types of switching:
• U>0, i>0 (where U is the voltage phase of the inverter i is the phase current of the inverter): from transistors of gate 14 to the diodes 24 and Vice versa when the transistors 15;
• U<0, i<0: from transistors of gate 17 to the diodes 25 and Vice versa when the transistors 16 (switching processes are similar to the previous paragraph because of the symmetry of the diagram);
• U>0, i<0: reverse diode valves 14 and 15 to the transistor 16 and the diodes 25 and back.
• U<0, i>0: reverse diode valves 16 and 17 to the transistors 15 and the diodes 24 and back(when switching processes are similar to the previous paragraph because of the symmetry of the diagram);
So of the eight types of switching (including reverse switching) essentially can be divided into four types:
1) from the outside (top) of the controlled valve to shunt the diode of the same arm of the inverter;
2) conversely, from the shunt diode to controlled valve;
3) reverse diode valves one shoulder to the internal controlled valve and shunt diode of the other shoulder the same phase;
4) conversely, from the controlled valve and shunt diode to reverse the diodes.
Consider the processes at the different types of switching when the circuit switching circuits
1) Switching the first type, for example, when the switching current from the controlled valve 14 to unterweser the diode 24 is carried out in two stages.
In precomputational state, the current is conducted by switching the reactor 26 operated valves 14, 15, the reactor 27. The capacitor 18 is discharged, and the capacitor 19 is charged up to a voltage level in the DC voltage Ud is the voltage between the DC bus 29 and 35 (up to a voltage in units of energy recovery).
Switching starts locking controlled valve 14. Unlocked switching diodes 36 and 37 and is a smooth re-charging of the capacitors 18 and 19, the capacitor 18 is charged via a chain 26-36-18-37-27- (another phase) (DC link 6-5)-26, and the capacitor 19 recharged chain 42-19-40-37-27-(another phase) (DC link 5-6)-42. At the end of the first stage switching capacitors 18 and 19 are recharged to the same voltage level equal to the half of the Ud (up to a voltage 40...42) and unlocked shunt diode 24.
In the second phase of the switching current through the shunt diode increases gradually, and the current through the reactor 26 and the diode 36 gradually decreases, causing further recharging of the capacitors 18 and 19 (the value corresponding to the voltage 40...42). When the current through the reactor 26 and the diodes 36 zero, the diodes 36 are locked, and the process of switching over.
2) Switching the second type, for example, when the switching current from the shunt diode 24 to the driven valve 14 is in the ri phase.
In precomputational state, the current is conducted by shunt diodes 24, controlled by valve 15, the reactor 27. The capacitors 18 and 19 are charged to the same voltage level (up to a voltage in units of energy recovery 40...42).
Switching begins unlocking the controlled valve 14. The current through the shunt diodes 24 gradually decreases, and after 14 increases with the speed limited by the inductance of the switching reactors 26 and 27. The first stage switching ends when the current through the diodes 24 drops to zero.
In the second phase switching occurs overcharge condenser batteries 18 and 19 (18 discharges to zero on the contour chain 18-40-26-14-15-27-31-38-41-18 and 19 is charged to full voltage in the DC link on a path 19 to 42-(DC 6-5)-26-14-15-27-31-38-19). The second stage ends when the voltage on 18 becomes zero.
In the third stage open switching diodes 36, 37 and the "extra" current, resulting in 26, 27, 31 due to overcharging 18, 19, falls to the nominal value through the recovery units 40 and 41, respectively, then the switching diodes are locked and switching ends.
3) Consider the processes in the switching of the third type, for example from reverse diode valves 14, 15 to the driven valve 16 and a shunt diode 25. Switching the third type is carried out in two stages.
In before omputational state, the current is conducted to the reactor 27, reverse diodes of the valves 14, 15, the reactor 26. The capacitor Bank 18 is discharged to zero, and 19 is charged to the full voltage Ud (up to a voltage in units of energy recovery 40...42).
Switching begins unlocking the gate 16: current through it starts to smoothly grow, and through the diodes 14, 15 decrease smoothly. At the same time is a smooth overcharge condenser batteries 18, 19: 18 is charged via a chain 18-37-27-(another phase) (DC link 6-5)-26-36-18 and 19 is discharged through the chain of 19-41-37-27-(another phase) (DC link 5-6)-42-19. At the end of the first stage switching capacitors 18 and 19 are recharged to the same voltage level equal to half of the Ud (up to a voltage in units of energy recovery 40...42). Main current (load) flows through the circuit 31-16-25, to which is added the current overcharge 18, 19.
In the second stage switching opens the switching diode 38 and the overcurrent through the reactor 26, 27, 31, caused by overcharging 18, 19, fall through the recovery units 40, 41, respectively. At the end of the second phase of the currents through the reactor 26 and 27 are set to zero, and after a 31 - nominal switching diodes 36...38 are locked and switching ends.
4) Consider the processes by switching the fourth type, for example, from the controlled valve 16 and the bypass diode to the inverse diodes of the valves 14, 15. Switching che is vertigo type is carried out in two stages.
In precomputational state, the current is conducted to the reactor 31, a controlled valve 16 and the bypass diodes 25. Capacitor Bank 18, 19 are charged to the same voltage level equal to the half of the Ud (up to a voltage in units of energy recovery 40...42).
Switching starts locking controlled valve 16. The current flowing through 16 and 25 stops; unlocked switching diode 38 and begins a smooth overcharge condenser batteries 18 and 19: 18 discharges through the chain of 18-40-(DC 5-6)-(load)-31-38-41-18 and 19 is charged via a chain 19 to 42-(DC 6-5)-(load)-31-38-19. The first stage ends when the voltage on 18 becomes zero, and the 19 - equal to half of the voltage Ud.
In the second stage switching unlocks the reverse diodes 14, 15, through which penetrates the load current. Simultaneously with the diodes 14, 15 are opened switching diodes 36, 37; 37 gradually decreases the current of the reactor 31 (chain 31-38-41-37-27-31)caused by overcharging 18, 19, and 36 flows through the differential current of the valves 14, 15 and gradually increasing the current of the reactor 26. At the end of the second phase of the current through 31 becomes zero through 26 - nominal switching diodes 36...38 are locked and switching ends. The load current after switching flows through the circuit 27-15-14-26-(DC 5-6)-(load)-27.
All even the PEX types of switching the speed change of the voltage on capacitor batteries 18, 19 is determined by the magnitude of their capacity and value of the load current. The rate of change of voltage on the gates 14...17 when the lock is equal to the rate of change of voltage on the capacitors 18, 19. Thus, in a situation where one of the series-connected semiconductor devices, the gate is locked before the other (due to existing differences delays shutdown of devices and control channels), the voltage across it increases smoothly and by the time of unlocking the rest of the devices does not exceed the maximum allowable value. An additional effect is to reduce dynamic losses in semiconductor devices.
As an example of the inventive switching chain figure 4 shows the waveforms of the voltages on the three series-connected IGCTs-thyristors (4500, 4000 a) when the switch-off delay of the two of them to 1 µs. The variation of stresses on the devices in the closed position amounted to about 600 V, which is acceptable considering the recommended manufacturers of semiconductor devices stock voltage.
The waveforms depicted in figure 5, explain the operation of the transducer. Basic three-phase bridge inverter forms the basis U3 output voltage of the inverter with low switching frequency (in the example, the mains frequency is 50 Hz). The remaining difference voltage is each formed of a single-phase bridge inverters. The management of each of the single-phase bridge inverters is carried out with a phase shift relative to each other, thereby increasing the resulting frequency output voltage ripple. In the example, the switching frequency of power switches in each of the bridges is 267 Hz, and the resulting modulation frequency of 800 Hz.
Figure 5 the following notation:
REF0 - signal task,
US - voltage phase three-level three-phase bridge inverter,
V3 - job for series-connected bridge inverter phase equal to the difference between job, phase and voltage phase of the three-phase inverter,
U3 resulting output voltage of the Converter.
Sources of information
1. STATCOM Based on Multimodules of Multilevel Converters Under Multiple Regulation Feedback Control Yiqiang Chen and Boon-Teck OoiDEEE TRANSACTIONS ON POWER ELECTRONICS, VOL.14, NO. 5, SEPTEMBER 1999.
2. U.S. patent US 6621719 B2 (Sep.16, 2003) Converter with additional voltage addition or subtraction at the output STEIMER PETER (CH); VEENSTRA MARTIN (CH).
3. Mustafa, G.M., Bareghamyan G Century, Ruditsky RS, Kubina E.V.: Reduce dynamic losses of the transistors of the inverter by changing the slew rate of the DC capacitors. Copyright certificate №989711 (15.01.83), UDC 621.314.57 (088.8).
1. The voltage Converter made by a combined scheme, which includes the basic h-bridge multi-level (at least three-tier) three-phase inverter voltage is Oia, valves, formed by the serial connection is fully controlled semiconductor devices in the arms of the bridge, respectively included between the positive or negative DC bus and the corresponding phase output, and one or more series-connected AC single-phase bridge inverters included in each phase at the output of the basic inverter, characterized in that each arm is a basic inverter introduced a chain of series-connected capacitor, the first switching diode is connected to the first capacitor plate and the second switching diode is connected to the second capacitor plate, and two commutating reactor, and this chain is connected in parallel to the valve shoulder so that the first switching diode is connected to the gate side of the DC bus, one commutating reactor connected between a corresponding DC bus and the connection point of the first switching diode and the gate of the shoulder, and the second commutating reactor is between the connection point of the second switching diode with the gate arm and the respective phase output, while the switching diodes are connected with the valves shoulder the same electrodes; in each phase of the inverter introduced three recuperating block, two of which inputs included is each between a corresponding DC bus and the connection point of the capacitor and the first switching diode, at the entrance of the third recuperating unit connected between the connection points of the capacitors adjacent shoulders of phase with the second switching diodes, and the outputs of all recuperating blocks phase is included between the DC bus of the basic inverter.
2. The voltage Converter made by a combined scheme, which includes the basic h-bridge two-level three-phase inverter voltage on the gates formed by the serial connection is fully controlled semiconductor devices in the arms of the bridge, respectively included between the positive or negative DC bus and the corresponding phase output, and one or more series-connected AC single-phase bridge inverters included in each phase at the output of the basic inverter, characterized in that each arm is a basic inverter introduced a chain of series-connected capacitor and a switching diode, switching the reactor and recuperating block, and this chain is connected in parallel to the valve shoulder so that the switching diode is connected to the gate of the same electrode side of the DC bus, and the commutating reactor connected between a connection point of the switching diode with the gate and the DC bus; recupererais the th block entry is included between the respective DC bus and the connection point of the switching diode and a capacitor, and the output is connected to the DC bus of the basic inverter.
3. The voltage Converter made by a combined scheme, which includes the basic h-bridge two-level three-phase inverter voltage on the gates formed by the serial connection is fully controlled semiconductor devices in the arms of the bridge, respectively included between the positive or negative DC bus and the corresponding phase output, and one or more series-connected AC single-phase bridge inverters included in each phase at the output of the basic inverter, characterized in that each arm is a basic inverter introduced a chain of series-connected capacitor and a switching diode, switching the throttle and recuperating block, and this chain is connected in parallel chain of gates shoulder so that the switching diode is connected to the gate of the same electrode from the respective phase output, switching inductor included between the phase output and the connection point of the switching diode and gate, and recuperating the block input is enabled between specified phase output and the connection point of the capacitor and the switching diode, and the output is connected to the DC bus of the basic inverter.
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