CN201313231Y

CN201313231Y - Inverter air plasma cutting power supply system

Info

Publication number: CN201313231Y
Application number: CNU2008201564069U
Authority: CN
Inventors: 刘荣春
Original assignee: Shanghai Hugong Electric Welding Machine Manufacturing Co Ltd
Current assignee: Shanghai Hugong Electric Welding Machine Manufacturing Co Ltd
Priority date: 2008-12-02
Filing date: 2008-12-02
Publication date: 2009-09-23
Anticipated expiration: 2018-12-02

Abstract

The utility model discloses an inverter air plasma cutting power supply system which comprises a three-phase module, a first rectifying filter module, a chopping module, a second rectifying filter module, a current sampling module, a controller and a driving module which are orderly connected, wherein the other end of the driving module is respectively connected with the chopping module and an inverter module. The utility model has the advantages of stable voltaic arc, good arc starting features, strong compensation ability on undulation of the electric network, wide current regulation range, small size, light weight, small inverter noise and the like.

Description

A kind of contravariant air plasma cutting power supply system

Technical field

The utility model relates to a kind of cutting power supply system, relates in particular to a kind of contravariant air plasma cutting power supply system.

Background technology

Contravariant air plasma cutting is a kind of novel thermal cutting technology, compare with conventional cutter have the arcing initiation success rate height, arc voltage height, concentration of energy, advantage such as cutting power is strong, cutting speed is fast, slot is narrow, otch is smooth, distortion is little.In the last few years, progress along with inversion transformation technique, corresponding contravariant plasma cutting technique is also towards high-power, high efficiency, the direction of good stability develops, its cutting current also rises to more than 100 ampere by original tens amperes, has not only improved cutting speed greatly, and has improved cut quality.

But on cutting current (domestic maximum cutting current is 160A, is 200A abroad), inversion output waveform control technology and reliability, there is weak point.

The utility model content

The purpose of this utility model is to propose a kind of contravariant air plasma cutting power supply system, makes described power-supply system have arc stability, and the striking characteristic is good, and is strong to the compensation ability of power network fluctuation.

For achieving the above object, the utility model adopts following solution:

A kind of contravariant air plasma cutting power supply system, comprise the three-phase alternating current module, first rectification filtering module, copped wave module, inversion module, second rectification filtering module, current sample module, controller, the driver module that connect successively, the described driver module other end is connected with copped wave module, inversion module respectively.

Described inversion module adopts the single-phase bridge structure.

Described first rectification filtering module and second rectification filtering module are the single-phase half-wave rectifier circuit modules.

The input voltage of described three-phase alternating current module is three-phase 380V, 50Hz.

Described power-supply system adopts insulation bipolar transistor switches device.

Compare with traditional silicon rectifier formula, thyristor rectifier formula air plasma cutting power supply, the utlity model has arc stability, advantage such as the striking characteristic is good, and is strong to the compensation ability of power network fluctuation, and the electric current adjustable range is wide, and volume is little, and is in light weight, and the inversion noise is little.

Description of drawings

Fig. 1 is the theory diagram of the utility model preferred embodiment.

Fig. 2 is a current feedback computing circuit schematic diagram.

Fig. 3 is a current sample feedback circuit schematic diagram.

The specific embodiment

Below in conjunction with drawings and Examples the utility model is further described:

As shown in Figure 1, a kind of contravariant air plasma cutting power supply system, comprise the three-phase alternating current module, first rectification filtering module, copped wave module, inversion module, second rectification filtering module, current sample module, controller, the driver module that connect successively, the described driver module other end is connected with copped wave module, inversion module respectively.

Described inversion module adopts the single-phase bridge structure.

IGBT contravariant air plasma cutting power supply is made up of main circuit, drive circuit, control circuit and holding circuit four parts.Main circuit uses IGBT as switch element, inverter circuit adopts the single-phase bridge structure, it is less to be characterized in that voltage is born at IGBT She Ji the two poles of the earth, good stability, power output is higher, and energy consumption is low, adopt single-phase half-wave rectifier circuit to realize rectification function, simple in structure, in conjunction with smoothing choke, realize that big electric current smoothly exports.This power supply key technical index has: input voltage is three-phase 380V, 50Hz; The output floating voltage is 270V DC; The cutting operating voltage is 150V DC; The cutting current adjustable range is 30～160A; Cutting thickness (carbon steel) is 10～40mm; Cutting rate temporarily is 85%.The contravariant air plasma arc generally all adopts dc source, and power supply is had two important requirements: dropping characteristic and high floating voltage.

As shown in Figure 2, Fig. 2 is the current feedback computing circuit.WF is the error amplifier of dress in the PWM controller TL494CN, electric current given signal Ug i and current feedback signal Ufd constitute differential input mode, the output voltage U K of error amplifier WF (it is relevant to trigger pulsewidth with the output of PWM controller) is that UK=R2R1 * (Ugi-Ufd) the middle Ugi of (1) formula (1) is given like this, Ufd increases with electric current, UK=R2 R1 * (Ug i-Ufd) reduces gradually, as UK during greater than 4V (circuits for triggering reference voltage higher limit), the UK all-the-time stable is in 4V (corresponding triggering signal pulsewidth maximum).Simultaneously, increase because the electric power loop impedance voltage drop is linear with the electric current increase, in this interval, the corresponding power external characteristic curve is to be one of the starting point straight line of declivity a little with floating voltage U0.As UK＜4V, UK descends rapidly, and the corresponding power output voltage sharply descends until zero volt, and power supply obtains dropping characteristic.

As shown in Figure 3, dc source utilizes current divider that current feedback signal is sampled, and sampled signal is amplified after the LC filter circuit is handled, and is detected by current foldback circuit.When over-current phenomenon avoidance did not take place, the U2 input voltage was lower than secure threshold VREF, and its output voltage is for negative, and D instead ends partially, and T turn-offs, and sampled signal V1-will be sent to the PWM controller.When the overcurrent accident takes place when; the U2 input voltage surpasses secure threshold VREF; its output voltage is for just; multiplication factor generally gets 10 can satisfy system requirements; the quick conducting of D (U2 open loop amplifier multiple is very big); make T enter the saturation conduction state at once, sampled signal V1-to zero potential, is realized overcurrent protection by rapid clamp.Inverter is its core in the contravariant air plasma cutting power supply, design contravariant cutting power supply, especially a large power supply, and primary problem is as required inverter main circuit to be chosen meticulously.Full-bridge type inverter circuit switching tube operating voltage and operating current are all smaller, so the antisurge ability is strong, the reliability height, and the power output of full-bridge type inverter circuit is big.Switching device is one of inverter core, and IGBT integrates the advantage of MOSFET and GTR, the frequency height, and energy consumption is low, and reliability and controllability are good, are present optimal HF switch elements.Should be taken into account when selecting transformer for use aspect following two: 1) frequency is to the requirement of material.In this system, the operating frequency that requires transformer is in 15～20kHz scope, if use general material, silicon steel sheet for example, the operating frequency of system will be lower than 2kHz, this obviously can't satisfy the requirement of system's operate as normal, and operating frequency is high more, and corresponding silicon steel sheet price is also just high more.Can adopt the Fe-based amorphous alloy iron core, its frequency of utilization can reach 50kHz, is enough to satisfy system requirements, and that price will be low than the same function silicon steel sheet is many.2) requirements of saving energy.The amorphous alloy core transformer has high saturated magnetic induction, low-coercivity, low-loss (be equivalent to silicon steel sheet 1/3～1/5), low exciting curent, good characteristics such as temperature stability, make no-load losses far below the silicon steel transformer, can improve energy transfer efficiency by reducing leakage field.No matter be from satisfying system's rapidity, still from energy-conservation angle, adopting the amorphous alloy appendiron core transformer all is proper way.

The foregoing description provides to those of ordinary skills and realizes or use of the present utility model; those of ordinary skills can be under the situation that does not break away from the utility model thought; the foregoing description is made various modifications or variation; thereby protection domain of the present utility model do not limit by the foregoing description, and should be the maximum magnitude that meets the inventive features that claims mention.

Claims

1. contravariant air plasma cutting power supply system, it is characterized in that: comprise the three-phase alternating current module, first rectification filtering module, copped wave module, inversion module, second rectification filtering module, current sample module, controller, the driver module that connect successively, the described driver module other end is connected with copped wave module, inversion module respectively.

2. a kind of contravariant air plasma cutting power supply as claimed in claim 1 system, it is characterized in that: described inversion module adopts the single-phase bridge structure.

3. a kind of contravariant air plasma cutting power supply as claimed in claim 1 system, it is characterized in that: described first rectification filtering module and second rectification filtering module are the single-phase half-wave rectifier circuit modules.

4. a kind of contravariant air plasma cutting power supply as claimed in claim 1 system, it is characterized in that: the input voltage of described three-phase alternating current module is three-phase 380V, 50Hz.

5. a kind of contravariant air plasma cutting power supply as claimed in claim 1 system, it is characterized in that: described power-supply system adopts insulation bipolar transistor switches device.