CN202679256U - Frequency converter of non-phase shifting transformer - Google Patents

Abstract

The utility model discloses a frequency converter of non-phase shifting transformers. The frequency converter includes at least two non-phase shifting transformers and multiple power units, wherein each phase of each non-phase shifting transformer is connected with at least one power unit. The frequency converter can be used for various high voltage environments. Compared with a frequency converter which adopts phase-shifting transformers, connecting devices between the power units and the non-phase shifting transformers are effectively reduced, so when the capacity of the frequency converter increases, the growing number of internal devices of the frequency converter adopting the non-phase shifting transformers is smaller than the growing number of internal devices of the frequency converter adopting the phase-shifting transformers, and consequently the internal device increase of the frequency converter caused by the capacity increase is avoided, and the problem that the heat radiation influences the stable operation of the frequency converter is solved. The non-phase shifting transformers adopt the oil-immersed cooling mode, so the work heat can be effectively reduced, and the unstable phenomenon of the frequency converter caused by superheat is prevented. Besides, the power units mentioned in the scheme are single-phase power units, so the connecting devices, like copper bars between the power units and non-phase shifting transformers are reduced.

Description

A kind of frequency converter of non-phase shifting transformer

Technical field

The utility model relates to field of power electronics, relates in particular to a kind of frequency converter of non-phase shifting transformer.

Background technology

The typical topological structure of voltage-type middle low power frequency converter is H bridge cascaded structure, referring to Fig. 1, Fig. 1 is the machine system schematic diagram of conventional solution, take 30MVA as example, high voltage source is through phase shifting transformer, change the output of many group low voltages into, and the three phase mains of output has certain phase shift angle.

Three phase mains inputs to power cell, then the rectifying device rectification through power cell inside is DC power supply, another mistake becomes the adjustable single phase alternating current power supply of frequency behind capacitor filtering, each power unit cascade is got up at last again, reaches the function of output voltage.

The frequency converter of prior art adopts the phase shifting transformer technology, and the maximum size value of phase shifting transformer is 7MVA at present, if think so that the capacity of phase shifting transformer continues to do greatly, will propose very high requirement to system radiating so.

In addition, the tap of phase shifting transformer secondary winding is a lot, causes the radiating mode of phase shifting transformer can only adopt dry type forced air cooling heat radiation (because tap is many, cause poor sealing, all can not adopt the radiating mode of oil immersed type).The phase shifting transformer capacity is large, and the loss of transformer is just large, and the large heating of loss is just many, and the corresponding phase shifting transformer that just requires will mate good cooling system.And dry type forced air cooling radiating mode has the limitation of itself, after the heat radiation holding capacity, just needs to consider other radiating mode, otherwise owing to untimely damage and the unstable properties that causes device in the system of dispelling the heat.

After the capacity of frequency converter increased, the quantity of the phase shifting transformer of employing will correspondingly increase, but because the restriction of phase shifting transformer heat radiation, and can there be damage and the unstable properties of the device that heat dissipation problem causes in frequency converter.

The utility model content

In view of this, the utility model is to provide a kind of frequency converter of non-phase shifting transformer, because frequency inverter capacity increases, and phase shifting transformer quantity is corresponding increase also, causes the problem of frequency converter unstable properties owing to dispel the heat to solve above-mentioned.

To achieve these goals, the utility model adopts following technical scheme:

A kind of frequency converter of non-phase shifting transformer comprises: at least two non-phase shifting transformers and some power cells; Wherein, each phase of each non-phase shifting transformer connects a power cell at least.

Described non-phase shifting transformer is for adopting the non-phase shifting transformer of oil immersed type cooling.

Described power cell is the single-phase power unit.

Described unidirectional power unit comprises: unidirectional controlled rectification circuit, filter circuit, DC support circuit and inverter circuit.

Described unidirectional controlled rectification circuit is comprised of 4 IGCT and the Absorption Capacitance that is used for high frequency.

Described filter circuit is the LC series resonant circuit.

Described DC support circuit is for being used for the thin-film capacitor of filtering.

Described inverter circuit is comprised of 4 IGCT and the Absorption Capacitance that is used for high frequency.

Described frequency converter is the high voltage converter of 3kv ~ 10kv.

The related power cell of the present embodiment adopts the single-phase commutation technique of controlling, and power device uses the higher IGCT module of voltage withstand class, thereby reduces the number of phases of power supply, has further reduced the number of devices of power cell inside.

With respect to prior art, the beneficial effect of this programme shows:

1, reduced the secondary number of taps of power cell, thereby for the radiating mode that adopts oil immersed type provides possibility, radiating effect is better;

2, solved the problem of input harmonics, so can adopt common electric power step-down transformer, secondary side need not to consider phase shift, so so that the capacity of transformer accomplish enough large, thereby so that the capacity of frequency converter also enough greatly.

Description of drawings

Fig. 1 is the machine system schematic diagram of conventional solution;

Fig. 2 is the electrical structure diagram of present embodiment power cell;

Fig. 3 is the present embodiment complete machine structure figure.

Embodiment

For clearly demonstrating the technical scheme in the utility model, the below provides preferred embodiment and is described with reference to the accompanying drawings.

Frequency converter in an embodiment is that high pressure range is at the high voltage converter of 3kv ~ 10kv.This frequency converter comprises a plurality of non-phase shifting transformers and a plurality of power cell, and the transformer that voltage-phase is identical between the described secondary winding is non-phase shifting transformer; Wherein, each phase of each described non-phase shifting transformer connects a power cell at least.

This frequency converter can be used for various hyperbaric environments, compare with the frequency converter that adopts phase shifting transformer, can effectively reduce the interface unit between power cell and the non-phase shifting transformer, thereby after frequency inverter capacity increases, internal components is compared with the frequency converter that adopts phase shifting transformer, it is less that device increases, and avoided because the capacity increase causes the frequency converter internal components many, and heat radiation affects the problem of frequency converter steady operation.

Preferably, power cell can adopt the single-phase power unit, thereby reduces the interface unit between power cell and the non-phase shifting transformer, such as copper bar etc.

Preferably, non-phase shifting transformer adopts the oil immersed type type of cooling, can effectively reduce work calories, avoids causing frequency converter because the wild effect of overheated appearance.

Referring to Fig. 2, be the electrical schematic diagram of present embodiment power cell, this power cell mainly comprises rectification circuit, filter circuit, DC support circuit and inverter circuit.Wherein rectification circuit is comprised of 4 gate-controlled switch device IGCT, the Absorption Capacitance CW1 and the CW2 that are used for high frequency, and this rectification circuit is single phase-controlled rectification circuit.

Filter circuit is composed in series by inductance L S and Absorption Capacitance CW5, is used for eliminating the voltage ripple in the unit, reduces simultaneously the usage quantity of dc bus place filter capacitor.

The DC support circuit is composed in parallel by two thin-film capacitor C1, C2.

Inverter circuit mainly is comprised of two Absorption Capacitance CW3, CW4 and 4 gate-controlled switch device IGCT that are used for high frequency.

Referring to Fig. 3, Fig. 3 is the system diagram of an embodiment of the frequency converter of a kind of non-phase shifting transformer of the utility model, take 30MVA as example, the high voltage source inlet wire is comprised of 5 oil-immersed power transformers, the capacity of each transformer is 6MVA, no-load voltage ratio is 10KV/1150V, three winding output of secondary side A, B, the C three-phase, each winding voltage is about 1150V, each winding is given a power cell power supply of every phase, export motor to behind every phase power unit cascade, transformer is positioned at the back of corresponding three unit that connect, and adopts copper bar to be connected between power cell and the transformer, transformer uses the oil immersed type type of cooling, and power cell adopts water-cooled.

Compare with the frequency converter that adopts phase shifting transformer, frequency converter of the present utility model can effectively reduce the device count of each power cell inside, reduce simultaneously transformer and be connected with cable between the power cell, than original technology, this programme can reduce the cost of system greatly.

For example, with 10kV, it is example that 30MVA adopts the frequency convertor system of phase shifting transformer and power cell, needs to adopt following device:

1, power cell adopts three-phase not control commutation technique, comprises 6 diodes in the rectification circuit;

2, in order to eliminate input harmonics, the 10kV system universal product is 9 level systems (9 power cells of every phase), every mutually in phase shifting angle be: α=60 °/9=6.7 °.

3, the phase shifting transformer heap(ed) capacity can be accomplished 7MVA, forms according to system, needs to use 6 (because phase shifting transformer can only adopt even number) 5MVA phase-shifting rectifier transformers, cooperates 27 (9 level system *, 3 phases) power cells;

4, be connected with 81 (3 cables in each unit or 27 unit of bronze medal *) cable or copper bars between transformer and the power cell;

5, phase shifting transformer needs forced air cooling, and every transformer top need to be equipped with 4 cooling blowers;

In embodiment of the present utility model, adopt the frequency convertor system of non-phase shifting transformer and power cell, need to adopt following device:

1, power cell adopts single-phase controlled rectification, comprises 4 IGCT in the rectification circuit of each power cell;

2, use 5 the non-phase shift electric power of 6MVA step-down transformers; Cooperate 15 power cells;

3, be connected with 30 copper bars between non-phase shifting transformer and the power cell;

4, because the tap of single transformer secondary reduces, can use the oil immersed type type of cooling, reduce apparatus cools blower fan quantity, raise the efficiency.

For the device of setting forth among each embodiment of the utility model, all within spirit of the present utility model and principle, any modification of doing, be equal to replacement, improvement etc., all should be included within the protection range of the present utility model.

Claims (9)

1. the frequency converter of a non-phase shifting transformer is characterized in that, comprising: at least two non-phase shifting transformers and some power cells; Wherein, each phase of each non-phase shifting transformer connects a power cell at least.

2. frequency converter according to claim 1 is characterized in that, described non-phase shifting transformer is for adopting the non-phase shifting transformer of oil immersed type cooling.

3. frequency converter according to claim 1 is characterized in that, described power cell is the single-phase power unit.

4. frequency converter according to claim 3 is characterized in that, described unidirectional power unit comprises: unidirectional controlled rectification circuit, filter circuit, DC support circuit and inverter circuit.

5. frequency converter according to claim 4 is characterized in that, described unidirectional controlled rectification circuit is comprised of 4 IGCT and the Absorption Capacitance that is used for high frequency.

6. frequency converter according to claim 4 is characterized in that, described filter circuit is the LC series resonant circuit.

7. frequency converter according to claim 4 is characterized in that, described DC support circuit is for being used for the thin-film capacitor of filtering.

8. frequency converter according to claim 4 is characterized in that, described inverter circuit is comprised of 4 IGCT and the Absorption Capacitance that is used for high frequency.

9. each described frequency converter is characterized in that according to claim 1 ~ 8, and described frequency converter is the high voltage converter of 3kv ~ 10kv.

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