CN203261232U - Chopper-type power supply circuit for plasma arc cutting - Google Patents

Abstract

The utility model discloses a chopping-type plasma arc cutting power supply circuit, which comprises a multi-winding transformer, at least two rectifying circuits and at least two chopper circuits; the multi-winding transformer includes one set of input windings and at least two sets of output windings, The input winding is a star winding or a delta winding, one of the two sets of output windings is a star winding, and the other output winding is a delta winding; the input winding is used to connect to a three-phase power supply, and the two sets of output windings are respectively connected to two A rectifier circuit, the two rectifier circuits are respectively connected to the two chopper circuits. In the utility model, the AC source, the multi-winding transformer and the four-way rectification circuit form a 12-pulse rectification module; the 12-pulse rectification is formed according to the Y/Δ combination of the multi-winding transformer secondary winding; the 12-pulse rectification makes cutting The input current of the power supply is in the same phase as the grid voltage, and the distortion of the current waveform is improved, thereby improving the power factor of the cutting power supply and reducing the influence of current harmonics on the grid.

Description

A power circuit for chopper plasma arc cutting

technical field

The utility model belongs to the technical field of plasma arc cutting, and more specifically relates to a chopping-type plasma arc cutting power supply circuit.

Background technique

Air plasma arc cutting is a thermal cutting technology that uses the high temperature of the plasma arc to partially melt and evaporate the metal to be cut, and at the same time blows the melted metal away from the base material with the help of high-speed plasma airflow, thereby forming a narrow incision. The temperature of the plasma arc column is high, far exceeding the melting point of all metals. It can cut any ferrous and non-ferrous metal materials and has a wide range of applications.

As the core of plasma cutting equipment, plasma arc cutting power supply has higher and higher requirements for power supply. In addition to the characteristics of constant current source with steep drop, the power requirement of power supply is higher, which can meet the needs of cutting thicker metal plates; power supply equipment can " Green" electricity consumption, reducing harmonic pollution to the grid.

The traditional cutting power supply is mainly based on silicon rectifier and thyristor rectifier, the equipment is bulky and heavy, and the dynamic and static characteristics are not ideal. With the improvement of the performance and control technology of power electronic components, the plasma arc cutting power supply has made great progress. Among all kinds of new topologies, the chopper type has the advantages of simple structure, high power, high switching frequency, good control characteristics and high reliability. advantages and has been widely used. However, the chopper type usually uses three-phase AC power to be stepped down by a power frequency transformer, and the DC voltage is obtained on the filter capacitor after uncontrolled rectification, and high-frequency chopping is performed through the IGBT switch tube, and a constant current with excellent characteristics is obtained after filtering by a high-power inductor. current to supply the cutting arc.

Since the input AC of the chopper-type cutting power supply is an uncontrolled rectification method, this rectification circuit will only have current input when the absolute value of the input voltage is greater than the capacitor voltage, thus making the input current a discontinuous approximate pulse type. The waveform has a low power factor, and this waveform is severely distorted and contains a large number of harmonic components, causing harmonic pollution to the power grid.

The output current of the current plasma cutting power supply is mostly 30-200A, and the general power is below 30KW, which cannot meet the requirements for cutting thick plates.

Utility model content

Aiming at the defects of the prior art, the utility model provides a chopping type plasma arc cutting power supply circuit, which aims to solve the problem that the power supply circuit provided by the prior art has a low power factor and contains a large number of harmonic components, which will cause harmonics to the power grid. pollution problem.

In order to achieve the above purpose, the utility model provides a chopping type plasma arc cutting power supply circuit, including a multi-winding transformer, at least two rectifying circuits and at least two chopper circuits; the multi-winding transformer includes a set of input windings and at least two sets of output windings, the input windings are star windings or delta windings, one set of output windings in the two sets of output windings is star windings, and the other set of output windings is delta windings; the input windings are used to connect three phase power supply, the two sets of output windings are respectively connected to two rectification circuits, the two rectification circuits are respectively connected to two chopper circuits, and the outputs of the two chopper circuits are connected in parallel and used to connect the load.

倍。Furthermore, the phase difference of the three-phase AC voltage of the two sets of output windings is 30 degrees; the phase voltage of one set of output windings is equal to the phase voltage of the other set of output windings

times.

The utility model also provides a chopping-type plasma arc cutting power supply circuit, which includes a multi-winding transformer, a four-way rectifier circuit and a four-way chopper circuit; the multi-winding transformer includes a set of input windings and four sets of output windings, The input winding is a star winding or a delta winding, the first output winding in the four sets of output windings is a delta winding, the second output winding is a star winding, the third output winding is a delta winding, and the fourth output winding is a star winding ; The input winding is used to connect the three-phase power supply, the first output winding is connected to the first rectifier circuit, and the first rectifier circuit is connected to the first chopper circuit; the second output winding is connected to the second rectifier circuit, and the second rectifier circuit is connected to the second chopper circuit; the third output winding is connected to the third rectifier circuit, the third rectifier circuit is connected to the third chopper circuit; the fourth output winding is connected to the fourth rectifier circuit, and the fourth rectifier circuit is connected to the fourth chopper circuit; the first chopper The outputs of the circuit, the second chopping circuit, the third chopping circuit and the fourth chopping circuit are connected in parallel and are used to connect a load.

Furthermore, the phase difference of the three-phase AC voltage between the first output winding and the second output winding is 30 degrees; the three-phase AC voltage between the third output winding and the fourth output winding The phase difference is 30 degrees.

倍；所述第三输出绕组的相电压为第四输出绕组的相电压的

倍。Furthermore, the phase voltage of the first output winding is equal to the phase voltage of the second output winding

times; the phase voltage of the third output winding is the phase voltage of the fourth output winding

times.

Furthermore, the a1 end of the a-phase winding, the b1 end of the b-phase winding and the c1 end of the c-phase winding in the star-shaped winding are connected.

Further, in the triangular winding, the a1 end of the a-phase winding is connected to the b2 end of the b-phase winding, the b1 end of the b-phase winding is connected to the c2 end of the c-phase winding, and the c1 end of the c-phase winding is connected to the a-phase The a2 ends of the winding are connected.

Furthermore, the rectification circuit includes a rectification bridge module, and an energy storage filter capacitor C1 connected in parallel to the output terminal of the rectification bridge module.

Furthermore, the rectifier bridge module includes: a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5 and a sixth diode Tube D6; the forward direction of the first diode D1 is connected to the negative direction of the second diode D2, the forward direction of the third diode D3 is connected to the negative direction of the fourth diode D4 The positive direction of the fifth diode D5 is connected to the negative direction of the sixth diode D6, and the three connection points are the input terminals of the rectifier bridge module, and the first diode D1 The negative direction of the third diode D3 and the negative direction of the fifth diode D5 are connected as the positive output terminal of the rectifier bridge module, and the negative direction of the second diode D2 The forward direction, the forward direction of the fourth diode D4 and the forward direction of the sixth diode D6 are connected to serve as the negative output terminal of the rectifier bridge module.

Furthermore, the chopper circuit includes a switch tube K1, a freewheeling diode D15, an anti-parallel diode D16 and an output reactor L1; one end of the output reactor L1 is used as the positive input terminal of the chopper circuit, and the The other end of the output reactor L1 is used as the positive output end of the chopper circuit, the base of the switching tube K1 is connected to the external PWM signal, and the collector of the switching tube K1 is connected to the anode of the freewheeling diode D15, so The collector of the switching tube K1 is also used as the negative output terminal of the chopper circuit, and the emitter of the switching tube K1 is used as the negative input terminal of the chopper circuit; the cathode of the freewheeling diode D15 is connected to the One end of the output reactor L1; the cathode of the anti-parallel diode D16 is connected to the collector of the switching tube K1, and the anode of the anti-parallel diode D16 is connected to the emitter of the switching tube K1.

In the utility model, the AC source, the multi-winding transformer and the four-way rectification circuit form a 12-pulse rectification module; the 12-pulse rectification is formed according to the Y/Δ combination of the multi-winding transformer secondary winding; the 12-pulse rectification makes cutting The input current of the power supply is in the same phase as the grid voltage, and the distortion of the current waveform is improved, thereby improving the power factor of the cutting power supply and reducing the influence of current harmonics on the grid. At the same time, the multi-winding structure of the secondary side of the transformer is very suitable for post-stage chopping. The inverter adopts modular design and works in parallel to improve the power level of the whole machine.

Description of drawings

Fig. 1 is the structural representation of the power supply circuit of chopping type plasma arc cutting that the utility model provides;

Fig. 2 is a schematic diagram of the connection of the star winding of the transformer in the power supply circuit of the chopping type plasma arc cutting provided by the utility model;

Fig. 3 is a schematic diagram of the connection of the transformer triangle winding in the power supply circuit of the chopping type plasma arc cutting provided by the utility model;

Fig. 4 is a structural schematic diagram of the rectifier circuit in the power supply circuit of chopping type plasma arc cutting provided by the utility model;

Fig. 5 is a schematic structural view of the chopping circuit in the power supply circuit of the chopping plasma arc cutting provided by the utility model;

Fig. 6 is a schematic diagram of the input current waveform of traditional uncontrolled rectification in the prior art;

Fig. 7 is an input current waveform diagram of 12-pulse rectification of the power supply circuit of chopping type plasma arc cutting provided by the utility model.

Detailed ways

In order to make the purpose, technical solution and advantages of the utility model clearer, the utility model will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model, and are not intended to limit the utility model.

The utility model aims at the shortcomings of low power factor and large harmonic content in the traditional chopper-type plasma arc cutting power supply, and proposes a 12-pulse rectification circuit, which improves the power factor of the cutting power supply and reduces current harmonics; for the current When the power level of the plasma cutting power supply is low, the utility model adopts the modular design of the rear-stage chopper, utilizes the structural characteristics of multiple windings on the secondary side of the transformer, and expands the power level of the whole machine through the parallel working mode of the modules.

The power supply circuit for chopper-type plasma arc cutting provided by the utility model includes a multi-winding transformer, at least two rectifier circuits and at least two chopper circuits; wherein, the multi-winding transformer includes one set of input windings and at least two sets of output windings, and the input The winding is a star winding or a delta winding, one of the two sets of output windings is a star winding, and the other output winding is a delta winding; the input winding is used to connect to a three-phase power supply, and the two sets of output windings are respectively connected to two rectifiers In the circuit, the two rectification circuits are respectively connected with the two chopper circuits, and the outputs of the two chopper circuits are connected in parallel and used for connecting the load.

In the plasma cutting power supply circuit of the utility model, the secondary winding of the multi-winding transformer adopts a combination of Y/Δ, and together with their respective rectifying circuits, constitutes a 12-pulse rectification. Compared with the traditional uncontrolled rectification method, the 12-pulse rectification improves the distortion of the input current waveform of the cutting power supply and reduces the impact of current harmonics on the power grid. In addition, since the secondary side of the multi-winding transformer adopts the structure of multiple output windings, it is very suitable for the modular design of the chopper circuit. The number of chopper power modules can be flexibly configured according to the power level of the required power supply to achieve high-power level Cutting current output. The chopper circuit adopts a modular design, which makes the plasma power supply more consistent and convenient for power supply production and maintenance.

For the convenience of explanation, the four-way rectifier circuit and the four-way chopper circuit are taken as examples and described in detail as follows in conjunction with the accompanying drawings:

As shown in Figure 1, the power supply circuit of chopper-type plasma arc cutting includes a multi-winding transformer 200, four-way rectification circuits 206, 207, 208, 209 and four-way chopper circuits 210, 211, 212, 213; 200 includes one set of input windings 201 and four sets of output windings 202, 203, 204, 205, the input winding 201 is a star winding or a delta winding, the first output winding 202 of the four sets of output windings is a delta winding, and the second output winding 203 It is a star winding, the third output winding 204 is a delta winding, and the fourth output winding 205 is a star winding; the input winding 201 is used to connect to a 380V three-phase power supply, the first output winding 202 is connected to the first rectifier circuit 206, and the first rectifier The circuit 206 is connected to the first chopping circuit 210; the second output winding 203 is connected to the second rectifying circuit 207, and the second rectifying circuit 207 is connected to the second chopping circuit 211; the third output winding 204 is connected to the third rectifying circuit 208, and the third rectifying circuit The circuit 208 is connected to the third chopping circuit 212; the fourth output winding 205 is connected to the fourth rectifying circuit 209, and the fourth rectifying circuit 209 is connected to the fourth chopping circuit 213; the first chopping circuit 210, the second chopping circuit 211, the fourth chopping circuit 213 The outputs of the third chopping circuit 212 and the fourth chopping circuit 213 are connected in parallel and used for connecting a load.

In the embodiment of the utility model, the AC source, the multi-winding transformer and the four-way rectification circuit form a 12-pulse rectification module; according to the Y/Δ combination of the multi-winding transformer secondary winding, the 12-pulse rectification is formed; the four-way chopping The circuit structure is exactly the same, and they are all composed of high-power switching tubes, freewheeling diodes, and filter inductors. They respectively perform high-frequency chopping on the DC voltage obtained by four-way rectification, and obtain a constant current with steep drop characteristics after filtering the inductors, which are used for cutting arc load. Due to the 12-pulse rectification, the input current of the cutting power supply is in the same phase as the grid voltage, and the distortion of the current waveform is improved, thereby improving the power factor of the cutting power supply and reducing the influence of current harmonics on the grid. At the same time, the secondary side of the transformer has a multi-winding structure , It is very suitable for the rear stage chopper to adopt a modular design and work in parallel to improve the power level of the whole machine.

In the power supply circuit of the utility model, when the output cutting current is greater than 1/2 of the rated current, two groups of 12-pulse rectifier circuits and four-way chopper circuits work simultaneously; when the output cutting current is less than or equal to 1/2 of the rated current At this time, only one group of 12-pulse rectification circuits and corresponding two-way chopper circuits are working; another group of 12-pulse rectification circuits and corresponding two-way chopper circuits provide redundant backup.

In the embodiment of the utility model, the primary side of the multi-winding transformer is a set of input windings; there are two connection modes of the windings, star (Y) connection and delta (Δ) connection, called star (Y) The winding of the connection method is a star winding, and the winding of the delta (Δ) connection is a delta winding. The specific connection methods of the star (Y) connection and the delta (Δ) connection are described in detail in conjunction with Figure 2 and Figure 3 as follows:

As shown in Figure 2, the star (Y) connection method: the a1 end of the a-phase winding and the b1 end of the b-phase winding are connected to the c1 end of the c-phase winding at the same time. That is, the a1 end of the a-phase winding, the b1 end of the b-phase winding and the c1 end of the c-phase winding in the star winding are connected.

As shown in Figure 3, the triangle (Δ) connection method: the a1 end of the a-phase winding is connected to the b2 end of the b-phase winding, the b1 end of the b-phase winding is connected to the c2 end of the c-phase winding, and the c1 end of the c-phase winding The end is connected to the a2 end of the a-phase winding. That is, the a1 end of the a-phase winding in the delta winding is connected to the b2 end of the b-phase winding, the b1 end of the b-phase winding is connected to the c2 end of the c-phase winding, and the c1 end of the c-phase winding is connected to the a2 end of the a-phase winding connect.

倍，这样两种接法的副边绕组的输出电压相等。The secondary sides of the multi-winding transformer 200 are four sets of windings isolated from each other, two sets of which are Y-connected and the other two sets are Δ-connected. The connection method is the same as above, and will not be repeated here. The difference in connection between the secondary delta winding and the star winding of the multi-winding transformer 200 makes the three-phase AC voltage phases of the windings of the two connections stagger by 30 degrees. The phase voltage of the delta winding on the secondary side of the multi-winding transformer 200 is the phase voltage of the star winding

times, so that the output voltages of the secondary windings of the two connections are equal.

Among them, among the four sets of windings on the secondary side of the multi-winding transformer, a set of star windings and a set of delta windings form a set of 12-pulse rectification circuits together with their respective rectification circuits; another set of star windings and another A group of delta windings together with their respective connected rectifier circuits form another group of 12-pulse rectifier circuits.

As shown in FIG. 4 , the rectification circuit includes a rectification bridge module and an energy storage filter capacitor C1 connected in parallel at the output end of the rectification bridge module. Wherein, the rectifier bridge module includes: a first diode D1, a second diode D2, a third diode D3, a fourth diode D4, a fifth diode D5 and a sixth diode D6; The forward direction of a diode D1 is connected to the negative direction of the second diode D2, the forward direction of the third diode D3 is connected to the negative direction of the fourth diode D4, and the forward direction of the fifth diode D5 and the negative connection of the sixth diode D6, the three connection points are the input terminals of the rectifier bridge module, the negative direction of the first diode D1, the negative direction of the third diode D3 and the fifth diode The negative phase of the tube D5 is connected as the positive output terminal of the rectifier bridge module, and the forward phase of the second diode D2, the forward phase of the fourth diode D4 and the forward phase of the sixth diode D6 are connected Then it is used as the negative output terminal of the rectifier bridge module.

In the embodiment of the present utility model, a set of 12-pulse rectification circuits 214 is formed by the winding 202 connected by Δ, the winding 203 connected by Y and the rectification circuits 206 and 207 connected correspondingly; the winding 204 connected by Δ and the Y connection The winding 205 of the winding 205 and the rectification circuits 208 and 209 connected thereto form another set of 12-pulse rectification circuit 215. The 12-pulse rectification makes the three-phase input current pulsate 12 times in each AC cycle, and the input current harmonics are greatly improved. reduced and improved power factor.

As shown in Figure 5, the chopper circuit includes: a switch tube K1, a freewheeling diode D15, an anti-parallel diode D16 and an output reactor L1; one end of the output reactor L1 is used as the positive input terminal of the chopper circuit, so The other end of the output reactor L1 is used as the positive output end of the chopper circuit, the base of the switch tube K1 is connected to the external PWM signal, the collector of the switch tube K1 is connected to the anode of the freewheeling diode D15, and the switch tube K1 The collector is also used as the negative output terminal of the chopper circuit, the emitter of the switch tube K1 is connected to the energy storage filter capacitor C1 and the negative output terminal of the rectifier bridge module, and the cathode of the freewheeling diode D15 is connected to the output reactor L1 The cathode of the anti-parallel diode D16 is connected to the collector of the switch tube K1, and the anode of the anti-parallel diode D16 is connected to the emitter of the switch tube K1. The chopper circuit performs high-frequency chopping on the rectified DC voltage, and obtains a constant current with steep drop characteristics after filtering the inductance, which is supplied to the cutting arc load.

Figure 6 shows the input current waveform diagram of traditional uncontrolled rectification. This kind of rectification circuit will have current input only when the absolute value of the input voltage is greater than the capacitor voltage, thus making the input current a discontinuous approximate pulse. Type waveform, low power factor, and this waveform is seriously distorted, contains a large number of harmonic components, causing harmonic pollution to the power grid. Fig. 7 shows the input current waveform diagram of the 12-pulse rectification of the chopper-type plasma arc cutting power supply circuit provided by the embodiment of the utility model. The 12-pulse rectification makes the input current of the cutting power supply the same phase as the grid voltage, and the current waveform The distortion is improved, thereby improving the power factor of the cutting power supply and reducing the influence of current harmonics on the power grid.

The power supply circuit of the chopper type plasma arc cutting provided by the utility model is a high-power level plasma cutting power supply with a current of more than 400A, which can be matched with the high-power cutting power supply of the numerical control machine tool. For applications where the overall power requirement is small, usually below 250A, a transformer with a small rated capacity can be used. The secondary side provides a set of star windings and a set of delta windings, and the two sets of windings correspond to the way of connecting two chopper modules; For applications that require greater overall power, a high-power transformer can be used. The secondary side provides three sets of star windings and three sets of delta windings, corresponding to the way of connecting six-way chopper modules to form three sets of 12-pulse rectification circuits. , not only achieve the effect of high power factor, but also improve the power level of the whole machine.

Those skilled in the art can easily understand that the above descriptions are only preferred embodiments of the present utility model, and are not intended to limit the present utility model. Any modifications, equivalent replacements and modifications made within the spirit and principles of the utility model Improvements and the like should all be included within the protection scope of the present utility model.

Claims (10)

1. the power circuit of a chopped mode plasma arc cutting, is characterized in that, comprises multi winding transformer, two-way rectification circuit and two-way chopper circuit at least at least;

Described multi winding transformer comprises one group of input winding and at least two groups output winding, and described input winding is star winding or delta windings, and in two groups of output windings, one group of output winding is star winding, and another group output winding is delta windings;

Described input winding is used for connecting three phase mains, and described two groups of output windings connect respectively the two-way rectification circuit, and the two-way rectification circuit connects respectively the two-way chopper circuit, and the output-parallel of two-way chopper circuit also is used for connecting load.

2. power circuit as claimed in claim 1, is characterized in that, two groups of output winding three-phase alternating voltage phase differences are 30 degree; The phase voltage of one group of output winding is exported the phase voltage of winding for another group

Doubly.

3. the power circuit of a chopped mode plasma arc cutting, is characterized in that, comprises multi winding transformer, No. four rectification circuits and No. four chopper circuits;

Described multi winding transformer comprises one group of input winding and four groups of output windings, described input winding is star winding or delta windings, in four groups of output windings, the first output winding is delta windings, the second output winding is star winding, the 3rd output winding is delta windings, and the 4th output winding is star winding;

Described input winding is used for connecting three phase mains, and the first output winding connects the first rectification circuit, and the first rectification circuit connects the first chopper circuit;

The second output winding connects the second rectification circuit, and the second rectification circuit connects the second chopper circuit;

The 3rd output winding connects the 3rd rectification circuit, and the 3rd rectification circuit connects the 3rd chopper circuit;

The 4th output winding connects the 4th rectification circuit, and the 4th rectification circuit connects the 4th chopper circuit;

The output-parallel of the first chopper circuit, the second chopper circuit, the 3rd chopper circuit and the 4th chopper circuit and be used for to connect load.

4. power circuit as claimed in claim 3, is characterized in that, the three-phase alternating voltage phase difference between described the first output winding and described the second output winding is 30 degree; Three-phase alternating voltage phase difference between described the 3rd output winding and described the 4th output winding is 30 degree.

5. power circuit as claimed in claim 3, is characterized in that, the phase voltage of described the first output winding is the phase voltage of the second output winding

Doubly; The phase voltage of described the 3rd output winding is the phase voltage of the 4th output winding

Doubly.

6. power circuit as described in claim 1 or 3, is characterized in that, in described star winding, the c1 end of the b1 end of the a1 of a phase winding end, b phase winding and c phase winding is connected.

7. power circuit as described in claim 1 or 3, it is characterized in that, in described delta windings, the b2 end of the a1 of a phase winding end and b phase winding is connected, and the b1 end of b phase winding and the c2 end of c phase winding are connected, and the c1 end of c phase winding and the a2 end of a phase winding are connected.

8. power circuit as described in claim 1 or 3, is characterized in that, described rectification circuit comprises rectifier bridge module, and the energy storage filter capacitor C1 that is connected in parallel on described rectifier bridge module output.

9. power circuit as claimed in claim 8, is characterized in that, described rectifier bridge module comprises: the first diode D1, the second diode D2, the 3rd diode D3, the 4th diode D4, the 5th diode D5 and the 6th diode D6;

The forward of described the first diode D1 is connected with the negative sense of described the second diode D2, the forward of described the 3rd diode D3 be connected the negative sense of the 4th diode D4 and connect, the forward of described the 5th diode D5 be connected the negative sense of the 6th diode D6 and connect, three tie points are the input of described rectifier bridge module;

The negative sense of the negative sense of the negative sense of described the first diode D1, described the 3rd diode D3 and described the 5th diode D5 rear positive output end as described rectifier bridge module that is connected;

The forward of the forward of the forward of described the second diode D2, described the 4th diode D4 and described the 6th diode D6 rear negative output terminal as described rectifier bridge module that is connected.

10. power circuit as described in claim 1 or 3, is characterized in that, described chopper circuit comprises switching tube K1, sustained diode 15, anti-and diode D16 and out put reactor L1.

The end of described out put reactor L1 is as the positive input terminal of described chopper circuit, and the other end of described out put reactor L1 is as the positive output end of described chopper circuit,

The base stage of described switching tube K1 connects outside pwm signal, the collector electrode of described switching tube K1 is connected to the anode of sustained diode 15, the collector electrode of described switching tube K1 is also as the negative output terminal of described chopper circuit, and the emitter of described switching tube K1 is as the negative input end of described chopper circuit; The negative electrode of described sustained diode 15 is connected to the end of described out put reactor L1,

The described anti-also negative electrode of diode D16 is connected to the collector electrode of described switching tube K1, and the anodic bonding of described anti-also diode D16 is to the emitter of described switching tube K1.

Images