CN2558157Y

CN2558157Y - Five-level high voltage frequency changer

Info

Publication number: CN2558157Y
Application number: CN 02224335
Authority: CN
Inventors: 刘文辉
Original assignee: CHANGSHA WEI'ER AUTOMATION TECHNOLOGY DEVELOPMENT Co Ltd
Current assignee: Changsha Wei'er Automation Technology Development Co., Ltd.; Henan Electric Power Experiment Research Institute
Priority date: 2002-06-28
Filing date: 2002-06-28
Publication date: 2003-06-25
Anticipated expiration: 2012-06-28

Abstract

The utility model discloses a five-level high-voltage frequency inverter based on a voltage-resistance IGCT or IGBT device over 4500 V. a secondary main transformer of the frequency inverter is provided with 6 groups of output windings. Each output winding is respectively connected with a rectification circuit, an over-current protection circuit, a DC filter circuit, an over-voltage clamping circuit and a single-phase voltage type invert circuit; the AC outputs of every two single-phase voltage type invert circuits are in series connection with each other to form one-phase AC output; the AC output of each phase is connected with an L C filter circuit. The high-voltage frequency inverter uses fewer power devices, and the power devices are not in series connection with each other to be run with input power factor over 0.95. Thus the utility model can be variously applicable for the high-voltage frequency-conversion speed-adjusting apparatus of 6 KV/ 10 KV 1000 KW ---- 6000 KW series to provide the energy transformation circuit for the frequency-transformation speed-adjusting apparatus of high-voltage large-capacity asynchronous motor.

Description

Five-level high-voltage frequency converter

Technical field:

The utility model relates to a kind of frequency converter, refers in particular to a kind of five-level high-voltage frequency converter.

Technical background:

Along with the development of power electronic technology, the RHVC that adopts power semiconductor device to constitute is widely used, controls the running of alternating current motor with it, can effectively reduce the starting-impact of motor, improves the life-span of motor.But during variable-frequency governor development still is mainly used in so far, on low capacity and the low voltage motor, and in the mine, control gold, chemical industry.In high-power, the high-tension motor of a large amount of uses of industrial departments such as ancient oil, building materials, still adopt constant speed to exchange transmission in a large number, its Flow-rate adjustment is and adopts throttling regulative mode with baffle plate or movable vane, cause a large amount of throttling losses, blower fan and motor operate in inefficient service area, and energy waste is serious.

At present, high voltage variable frequency speed regulator mainly contains two kinds:

1, " high and low, height " frequency conversion speed-adjusting system earlier becomes voltage with high pressure drop, boosts with step-up transformer after the frequency conversion again, and this governing system exists that volume is big, cost is high, complex structure, the shortcoming big to electric network pollution.

2, adopt GTO or SCR device, the main circuit of its variable-frequency governor has two kinds of versions: a kind of is to adopt units in series single-phase bridge inverter circuit, this sharp structure makes that owing to the IGBT number of devices of using the signal modulation is complicated, and the global reliability of system is poor; Another kind is to adopt diode clamp tri-level inversion circuit, since the highest withstand voltage 6500V that has only of high pressure IGCT and IGBT device, when inverter output voltage reaches 6KV, need be with IGCT or the direct series operation of IGBT device, increase the cost of system like this, reduced the reliability of system.

The utility model content:

The purpose of this utility model is to provide the five-level high-voltage frequency converter that a kind of power device number is few, power device does not need direct series operation, power factor (PF) is high.

For achieving the above object; the utility model is taked following technical proposals: the utility model comprises main circuit; control circuit; described main circuit comprises main transformer; rectification circuit; circuit overcurrent protection; the DC filtering circuit; the overvoltage clamp circuit; inverter circuit; filter circuit; tool is characterised in that: the secondary of described main transformer has six groups to export windings; every output winding is connected to rectification circuit successively respectively; circuit overcurrent protection; the DC filtering circuit; the overvoltage clamp circuit; single-phase electricity die mould inverter circuit; the interchange output series connection mutually of per two single-phase electricity die mould inverter circuits; constitute cross streams output, every cross streams output is connected to the LC filter circuit.

Secondary every group of winding output line voltage of above-mentioned main transformer is followed successively by 10 degree, 20 degree, 30 degree, 40 degree, 50 degree, 60 degree with respect to the phase place of former limit winding wire voltage, and each winding meets the following conditions:

A1＝B1＝C1，a1＝b1＝c1＝a8＝b8＝c8，a2＝b2＝c2＝a9＝b9＝c9

A3＝b3＝c3＝a6＝b6＝c6，a4＝b4＝c4＝a7＝b7＝c7，a5＝b5＝c5

A1∶a1＝4.984∶1，A1∶a2＝16.97∶1，A1∶a3＝9.81∶1，A1∶a4＝8.635∶1

A1∶a5＝5.906∶1，A1∶a10＝3.41∶1。

Each is made up of above-mentioned overvoltage clamp circuit a reactance, a resistance, a diode, an electric capacity, reactance is serially connected with between the input of rectification positive output end and single-phase electricity die mould inverter bridge, resistance is connected in series the back with diode in parallel with reactance, the input of diode cathode termination inverter circuit, electric capacity one termination rectification output negative power end, the other end and diode, resistance join.

The advantage that the utlity model has:

1), the power device that uses is few, reduced the cost of system, improved the reliability of system.

2), adopt the coupled in series of half-bridge converter in the main circuit, avoided the direct series operation of high-voltage high-power frequency transformator high power device in the past, improved the stability of system.

3), input adopts the sixfold commutation technique, and input power factor is reached more than 0.95.

Describe structure of the present utility model and operation principle in detail below in conjunction with accompanying drawing.

Description of drawings:

Fig. 1 is for exchanging input isolation, rectification, filter circuit figure.

Fig. 2 is five level voltage type inverter circuit figure of the sinewave output of employing IGCT.

Fig. 3 is A the 1st grade of single-phase bridge switching tube gate drive voltage waveform mutually.

Embodiment:

Referring to accompanying drawing 1, isolating transformer TR secondary is exported six group of three phase winding, former limit input line voltage is 6KV, every group of winding output voltage of secondary is 1760V, and as shown in the figure, every group of winding output line voltage is followed successively by 10 degree, 20 degree, 30 degree, 40 degree, 50 degree, 60 degree with respect to the phase place of former limit winding wire voltage.Can guarantee that so the former limit of transformer input power factor reaches more than 0.95, the total percent harmonic distortion of input current is less than 5%.The voltage of every group of direct voltage source reaches 2500V after the rectification, thereby guarantees that back Pyatyi electrical level inverter output line voltage effective value can reach 6KV, and in order to reach above requirement, transformer secondary umber of turn is than also meeting the following conditions:

A1＝B1＝C1?a1＝b1＝c1＝a8＝b8＝c8，a2＝b2＝c2＝a9＝b9＝c9，

A3＝b3＝c3＝a6＝b6＝c6，a4＝b4＝c4＝a7＝b7＝c7，a5＝b5＝c5

A1∶a1＝4.984∶1，A1∶a2＝16.97∶1，

A1∶a3＝9.81∶1，A1∶a4＝8.635∶1，

A1∶a5＝5.906∶1，A1∶a10＝3.41∶1，

BRA1, BRA2, BRB1, BRC1, BRC2 are respectively the three phase full wave rectification bridge.SA1, SA2, SB1, SB2 are the withstand voltage IGCT device of 4500V; SA1, SA2, SB1, SB2, SC1, SC2 constitute the overcurrent protection electronic switch; when back level inverter circuit generation overcurrent fault, turn-off rapidly; the safety of protection main circuit device, RSTA1, RSTA2, RSTB1, RSTB2, RSTC1, RSTC2 play the effect that suppresses the charging current of electric capacity EA1, EA2, EB1, EB2, EC1, EC2 when input is closed a floodgate respectively.

Referring to Fig. 3, in the five level voltage type inverter circuits of the sinewave output of employing IGCT, the interchange output series connection mutually of two half-bridge converters in 6 single-phase electricity die mould inverter bridge, constitute cross streams output, constitute three-phase alternating current output altogether, one of three-phase alternating current output terminates to together as neutral point, and the other end is connected to output LC filter circuit as the output of three-phase respectively.Each single-phase electricity die mould inverter bridge is made up of four IGCT devices, and it is the two level single-phase electricity die mould inverter bridge connection of a standard that its circuit connects.

U, C, W are inverter output three-phase alternating current pressure sides, use for load motor, dc bus DCA1+, DCA1-, DCA2+, DCA2-, DCB1+, DCB2-, DCB1+, DCB2-, DCC1+, DCC1-, DCC2+, DCC2-are respectively from the direct voltage source of Fig. 1, every group rated direct voltage is 2500V, and the used device for power switching SAL11-SAR22 of inversion, SBL11-SBR22, SCL11-SCR22 are the withstand voltage IGCT of 4500V.Reactance LAA1, LAA2, LBA1, LBA2, LCA1, LCA2 are used to suppress the electric current rate of climb that brachium pontis IGCT opens.DAA1/CAA1/RAA1, constitute the overvoltage clamp circuit of each brachium pontis IGCT respectively.LA/CA, LB/CB, LC/CC constitute A, B, C phase output voltage filter circuit respectively, make three-phase output voltage near sinusoidal wave.

In order to guarantee that inverter output voltage satisfies the requirement of asynchronous motor to power supply, all adopting particular harmonic to eliminate the resulting pulse of PWM algorithm to the six level voltage type inverter circuits that use the IGCT device modulates, and specific angle of driving pulse phase phasic difference of two single-phase bridges that whenever are in series, thereby make every phase output voltage reach five level, guarantee the sinusoidal degree of output voltage.Provided the A gate drive pulse waveform phase of the 1st grade of each switching tube of single-phase bridge mutually among Fig. 1, the gate drive pulse waveform phase of each switching tube of the 2nd grade of single-phase bridge of A phase is than specific angle of gate drive pulse waveform phase hysteresis of each switching tube of the 1st grade of single-phase bridge, to reach the purpose of eliminating specific times harmonic in the A phase output voltage.B mutually each switching tube gate drive pulse phase place than A mutually in each corresponding switching tube gate drive pulse phase place 120 degree that lag behind respectively, C mutually each switching tube gate drive pulse phase place than B mutually in each corresponding switching tube gate drive pulse phase place 120 degree that lag behind respectively.

Claims

1; a kind of five-level high-voltage frequency converter; comprise main circuit; control circuit; described main circuit comprises main transformer; rectification circuit; circuit overcurrent protection; the DC filtering circuit; the overvoltage clamp circuit; inverter circuit; filter circuit; it is characterized in that: the secondary of described main transformer has six groups to export windings; every output winding is connected to rectification circuit successively respectively; circuit overcurrent protection; the DC filtering circuit; the overvoltage clamp circuit; single-phase electricity die mould inverter circuit; the interchange output series connection mutually of per two single-phase electricity die mould inverter circuits; constitute cross streams output, every cross streams output is connected to the LC filter circuit.

2, five-level high-voltage frequency converter according to claim 1, it is characterized in that: secondary every group of winding output line voltage of described main transformer is followed successively by 10 degree, 20 degree, 30 degree, 40 degree, 50 degree, 60 degree with respect to the phase place of former limit winding wire voltage, and each winding meets the following conditions:

A1＝B1＝C1，a1＝b1＝c1＝a8＝b8＝c8，a2＝b2＝c2＝a9＝b9＝c9

A3＝b3＝c3＝a6＝b6＝c6，a4＝b4＝c4＝a7＝b7＝c7，a5＝b5＝c5

A1∶a5＝5.906∶1，A1∶a10＝3.41∶1。

3, five-level high-voltage frequency converter according to claim 1, it is characterized in that: each is made up of described overvoltage clamp circuit a reactance, a resistance, a diode, an electric capacity, reactance is serially connected with between the input of rectification positive output end and single-phase electricity die mould inverter bridge, resistance is connected in series the back with diode in parallel with reactance, the input of diode cathode termination inverter circuit, electric capacity one termination rectification output negative power end, the other end and diode, resistance join.