CN201323532Y - Mid-position clamp circuit of three-level voltage source type frequency converter - Google Patents
Mid-position clamp circuit of three-level voltage source type frequency converter Download PDFInfo
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- CN201323532Y CN201323532Y CNU2008201438244U CN200820143824U CN201323532Y CN 201323532 Y CN201323532 Y CN 201323532Y CN U2008201438244 U CNU2008201438244 U CN U2008201438244U CN 200820143824 U CN200820143824 U CN 200820143824U CN 201323532 Y CN201323532 Y CN 201323532Y
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Abstract
The utility model relates to a mid-position clamp circuit of a three-level voltage source type frequency converter, wherein clamp diodes are added on the original two-level basis to form a three-level circuit; an insulated gate bipolar transistor (IGBT) is adopted as an inverter-part power device; a flywheel diode in inverse parallel is integrated inside the IGBT; two groups of capacitors for voltage division are adopted in the direct current link to generate a central point; a di/dt limiting circuit, a common mode reactor and the like are also arranged in the direct current link; the IGBT of each phase of a three-phase frequency converter is provided with one clamp diode in a way that the two ends of the clamp diode are connected in the mid position of the IGBT of each phase; the mid position of a capacitor assembly is connected with the mid position of each phase of the three-phase frequency converter; and the alternating current output from each phase of the frequency converter is supplied to a load. The number of voltage level of the output phase is increased from 2 to 3, the number of line voltage level is increased from 3 to 5, the quality of the output waveform is greatly improved, the dv/dt output is reduced correspondingly, and the breakdown voltage required for the power device is reduced by half. The mid-position clamp circuit is applied in various fields, such as medium/high-voltage frequency conversion and speed control, active power filter and power system reactive compensation.
Description
Technical field
The utility model belongs to frequency-converter device inverter voltage control technology field, relates to a kind of three-level voltage source type frequency converter neutral point clamp circuit, is applied to fields such as mesohigh frequency control, Active Power Filter-APF and power system reactive power compensation.
Background technology
Along with the development of power electronic technology, microelectric technique and control theory, frequency converter has been widely used in the alternating current motor speed control.Use frequency converter and not only can save a large amount of electric energy, and the automatic control performance of frequency converter can improve the quality of products and quantity.
Existing two level converters in use must be realized high pressure output with withstand voltage higher device.Owing to have only two level output voltage waveforms shakinesses.Level number is lower, only is two level, and output voltage dV/dt is also bigger, needs to adopt extraordinary motor or the whole sine wave filter that adds high pressure, and its cost can increase many.
In PWM voltage-source type frequency converter, in (height) voltage frequency changer output voltage higher, the dynamic voltage balancing problem for avoiding device series connection to cause reduces output harmonic wave and du/dt simultaneously, inverter section can adopt many level mode, also is neutral point clamp (NPC) mode.
Advantages such as IGBT is widely used in the various voltage-source type PWM frequency converters, and it is fast to have a switch, and loss is little, and buffering and gate drive circuit are simple, but the electric current and voltage grade is subjected to the conduction voltage drop restriction.IGBT accomplishes 3300V, 1200A at present.The IGBT of 3300V forms three-level converter, and output AC voltage is up to 2.3KV.
Summary of the invention
Problem to be solved in the utility model is, overcome the deficiencies in the prior art, a kind of three-level voltage source type frequency converter neutral point clamp circuit is provided, promptly on original two level bases, increase clamping diode and constitute tri-level circuit, adopt IGBT as inversion part power device, the inverse parallel fly-wheel diode is integrated among the IGBT, DC link is with two groups of capacitance partial pressures, obtain central point, DC link also has the di/dt restricting circuits, common mode reactor etc., the every phase IGBT assembly of three phase converter is equipped with clamping diode, the clamping diode two ends connect with the mid point of every TGBT mutually, and the mid point of capacitor group connects the every alternating current supply load of drawing mutually of frequency converter with the every mid point mutually of three-level inverter.
The utility model solves its technical problem and takes following technical scheme to realize:
A kind of three-level voltage source type frequency converter neutral point clamp circuit that provides according to the utility model, comprise rectifier ZL, charging contactor K1, K2, capacitor group CF, inverter IGBT, clamping diode, the di/dt restricting circuits, common mode reactor GL and filter LP, it is characterized in that: alternating current is after rectifier ZL rectification, rectifier ZL delivery outlet and charging contactor K1, the K2 input port connects, direct current is through charging contactor K1, the K2 delivery outlet is connected with capacitor group CF, direct current is connected with inverter behind capacitor filtering, every phase brachium pontis adopts a pair of IGBT module series connection, the built-in fly-wheel diode of module, adopt diode (led) module to carry out clamp, inversion output is after give load altogether after the filter LP output.
It is to take following technical scheme further to realize that the utility model solves its technical problem:
Circuitry phase in aforesaid three groups of three-level inverters, by power switch V1～V4, sustained diode W1D～W4, clamping diode VC1, VC2 forms, two capacity such as capacitor Ed1, Ed2 of DC side, the group parallel connection of connecting with DW1, DW2, DW3, DW4 of V1, V2, V3, V4 series connection group, clamping diode VC1 links to each other with V1, V2 tie point, and VC2 links to each other with V3, V4 tie point, VC1 links to each other with the mid point C of capacitor group with the tie point of VC2, forms the circuitry phase in the electrical level inverter.
The utility model compared with prior art has significant advantage and beneficial effect:
Because utility model output phase voltage level number is increased to 3 from 2, line voltage level number then is increased to 5 by 3, each level magnitude reduces relatively, become the DC bus-bar voltage of half by whole DC bus-bar voltage, under the prerequisite of equal switching frequency, the output waveform quality is had greatly improved, the also corresponding decline of output dv/dt.Compare with two level converters, under identical output voltage condition, this structure also can make the required withstand voltage reduction of power device half.
Embodiment of the present utility model is provided in detail by following examples and accompanying drawing thereof.
Description of drawings
Fig. 1 is a schematic block circuit diagram of the present utility model;
Fig. 2 is basic circuit structure figure of the present utility model;
Fig. 3 is circuit theory diagrams of the present utility model.
Embodiment
Below (is example with Fig. 3), reach preferred embodiment in conjunction with the accompanying drawings, embodiment, structure, feature and effect thereof that foundation the utility model is provided, describe in detail as after.
Shown in Fig. 1～3, a kind of three-level voltage source type frequency converter neutral point clamp circuit, comprise rectifier ZL, charging contactor K1, K2, capacitor group CF, inverter IGBT, clamping diode, the di/dt restricting circuits, common mode reactor GL and filter LP, it is characterized in that: alternating current is after rectifier ZL rectification, rectifier ZL delivery outlet and charging contactor K1, the K2 input port connects, direct current is through charging contactor K1, the K2 delivery outlet is connected with capacitor group CF, direct current is connected with inverter behind capacitor filtering, every phase brachium pontis adopts a pair of IGBT module series connection, the built-in fly-wheel diode of module, adopt diode (led) module to carry out clamp, inversion output is after give load altogether after the filter LP output.Circuitry phase in three groups of three-level inverters, by power switch V1～V4, sustained diode W1D～W4, clamping diode VC1, VC2 forms, two capacity such as capacitor Ed1, Ed2 of DC side, the group parallel connection of connecting with DW1, DW2, DW3, DW4 of V1, V2, V3, V4 series connection group, clamping diode VC1 links to each other with V1, V2 tie point, and VC2 links to each other with V3, V4 tie point, VC1 links to each other with the mid point C of capacitor group with the tie point of VC2, forms the circuitry phase in the electrical level inverter.
Rectifier adopts 12 pulse diode rectification structures.Inversion part power device can adopt IGBT, and the inverse parallel fly-wheel diode is integrated among the IGBT, and DC link obtains central point with two groups of capacitance partial pressures.DC link also has the di/dt restricting circuits, common mode reactor etc.The every phase IGBT assembly of three phase converter is equipped with clamping diode, and the clamping diode two ends connect with the mid point of every TGBT mutually, and the mid point of capacitor group connects the every alternating current supply load of drawing mutually of frequency converter with the every mid point mutually of three-level inverter.
Operation principle: rectification circuit adopts 12 pulse diode rectification structures.Inversion part power device can adopt IGBT, and the inverse parallel fly-wheel diode is integrated among the IGBT.Because be subjected to the restriction of devices switch loss, especially turn-off power loss, the switching frequency of IGBT is about 1KHZ.
DC link obtains central point with two groups of capacitance partial pressures.DC link also has the di/dt restricting circuits, common mode reactor etc.
The di/dt restricting circuits is mainly by di/dt restriction reactor, antiparallel with it fly-wheel diode and resistance are formed, because itself can not control di/dt the IGBT device, so must be by adding the di/dt restricting circuits, make the reverse recovery of inverter IGBT inverse parallel fly-wheel diode be controlled in the safe operation scope current-rising-rate when this circuit also is used to limit short circuit simultaneously.
The common mode reactor generally separates arrangement at transformer and frequency converter, and adopts when cable is longer between the input of transformer secondary and rectifier bridge, when transformer and frequency converter are placed together, can save.Its effect mainly is to bear common-mode voltage and restriction high-frequency leakage current, and the design of common mode reactor is used for bearing common-mode voltage.The common-mode voltage of high frequency also can pass through output filter capacitor in addition, the transformer distributed capacitance, and cable distribution electric capacity forms path, produces high-frequency leakage current, influences device safety, and the common mode reactor also plays the effect that suppresses high-frequency leakage current.
Because inverter circuit adopts IGBT as power device, can rise by the detected set electrode voltage and carry out short-circuit detecting, and protect, so dc bus needn't add protective circuit by the gate pole shutoff.
Because DC link exists common mode reactor and di/dt restriction reactor; cause existing between rectifier bridge output and the filter capacitor big impedance; the surge voltage of electrical network will form surge current by rectifier bridge like this; the effect that absorbs by filter capacitor reduces greatly again; in order to protect rectifier diode to avoid the influence of surge voltage, at the rectifier bridge output-parallel resistance capaciting absorpting circuit.Clamping diode has guaranteed that the voltage that outermost two IGBT bear in the brachium pontis can not surpass the DC bus-bar voltage of half, exactly, should be the voltage of respective side filter capacitor, so there is not overpressure problems in outermost two IGBT.Two inboard devices are still wanted parallel resistance, to prevent to produce overvoltage.Because when two devices of homonymy are in blocking state simultaneously, the voltage that inboard device bears may surpass the DC bus-bar voltage of half, and concrete voltage depends on the leakage current matching relationship of two devices of homonymy.
Fig. 2 is the basic structure of three-level inverter one phase, and V1～V4 represents 4 power switchs in the phase brachium pontis, and DW1～DW4 is antiparallel fly-wheel diode, and VC1, VC2 are clamping diode, and all diodes require to have the voltage withstand class identical with power switch.Ed is one group of electric capacity two terminal voltage, and C is a central point.
Pass through the open-minded of power controlling device V1～V4 for every phase brachium pontis, turn-off, can obtain three kinds of varying level+Ed at the brachium pontis output point, 0 ,-Ed sees Table 1.
Table 1: the every phase output voltage of three-level converter device combination table
| V1 | V2 | V3 | V4 | Output voltage | State code |
| ON | ON | OFF | OFF | +Ed | P |
| OFF | ON | ON | OFF | 0 | C |
| OFF | OFF | ON | ON | -Ed | N |
Claims (2)
1. three-level voltage source type frequency converter neutral point clamp circuit, comprise rectifier (ZL), charging contactor (K1, K2), capacitor group (CF), inverter (IGBT), clamping diode, the di/dt restricting circuits, common mode reactor (GL) and filter (LP), it is characterized in that: alternating current is after rectifier (ZL) rectification, rectifier (ZL) delivery outlet and charging contactor (K1, K2) input port connects, direct current is through charging contactor (K1, K2) delivery outlet is connected with capacitor group (CF), direct current is connected with inverter behind capacitor filtering, every phase brachium pontis adopts a pair of IGBT module series connection, the built-in fly-wheel diode of module, adopt diode (led) module to carry out clamp, inversion output is after give load altogether after filter (LP) output.
2. three-level voltage source type frequency converter neutral point clamp circuit according to claim 1, it is characterized in that: the circuitry phase in described three groups of three-level inverters, by power switch (V1～V4), fly-wheel diode (DW1D～W4), clamping diode (VC1, VC2) form, two capacitor (Ed1 of DC side, capacity such as Ed2), V1, V2, V3, V4 series connection group and DW1, DW2, DW3, the parallel connection of DW4 series connection group, clamping diode VC1 and V1, the V2 tie point links to each other, VC2 and V3, the V4 tie point links to each other, VC1 links to each other with the mid point C of capacitor group with the tie point of VC2, forms the circuitry phase in the electrical level inverter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2008201438244U CN201323532Y (en) | 2008-12-03 | 2008-12-03 | Mid-position clamp circuit of three-level voltage source type frequency converter |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNU2008201438244U CN201323532Y (en) | 2008-12-03 | 2008-12-03 | Mid-position clamp circuit of three-level voltage source type frequency converter |
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| CN201323532Y true CN201323532Y (en) | 2009-10-07 |
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| CNU2008201438244U Expired - Fee Related CN201323532Y (en) | 2008-12-03 | 2008-12-03 | Mid-position clamp circuit of three-level voltage source type frequency converter |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101976967A (en) * | 2010-10-26 | 2011-02-16 | 深圳市盛弘电气有限公司 | Method for controlling balance of three-level inverter and direct current busbar voltage |
| CN102255540A (en) * | 2011-07-06 | 2011-11-23 | 阳光电源股份有限公司 | Method, circuit and converter for converting DC voltage into AC voltage |
-
2008
- 2008-12-03 CN CNU2008201438244U patent/CN201323532Y/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101976967A (en) * | 2010-10-26 | 2011-02-16 | 深圳市盛弘电气有限公司 | Method for controlling balance of three-level inverter and direct current busbar voltage |
| CN101976967B (en) * | 2010-10-26 | 2013-01-02 | 深圳市盛弘电气有限公司 | Method for controlling balance of three-level inverter and direct current busbar voltage |
| CN102255540A (en) * | 2011-07-06 | 2011-11-23 | 阳光电源股份有限公司 | Method, circuit and converter for converting DC voltage into AC voltage |
| CN102255540B (en) * | 2011-07-06 | 2013-06-26 | 阳光电源股份有限公司 | Method, circuit and converter for converting DC voltage into AC voltage |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20091007 Termination date: 20171203 |