CN101854122B - High-voltage inverted low-voltage chopped-mode welding power supply - Google Patents

Abstract

The invention discloses a high-voltage inverter and low-voltage chopper-type welding power supply, which consists of a DC power supply connected in series with a push-pull inverter circuit, a transformer, and a full-wave rectifier circuit, wherein an output terminal of the full-wave rectifier circuit is connected to a chopper The input terminal of the full-wave rectification circuit is connected to the input terminal of the filter component on the other output terminal. The invention not only reduces the manufacturing cost and power consumption of the inverter welding power supply, but also improves the working reliability, stability and dynamic characteristics of the inverter welding power supply.

Description

High voltage inverter low voltage chopper welding power supply

technical field

The invention relates to a high-power welding power supply for an electric welding machine, in particular to a new topology of a main circuit of a high-power inverter welding power supply.

Background technique

At present, compared with non-inverter welding power sources, inverter welding power sources have the characteristics of small size, light weight and high efficiency and energy saving. The main reasons are as follows:

The volume and weight of ordinary non-inverter welding power sources are mainly concentrated on transformers and reactors, and the proportion of the two can reach more than 80%. When designing a transformer, the following relationships exist:

U∝kfNB _m S (1)

k-constant (related to transformer primary side voltage form)

U-voltage applied to the primary winding of the transformer (V)

f- inverter frequency (Hz)

N-Number of turns of the primary winding

B _m - working magnetic flux density (T) (the size is related to the magnetic core material of the transformer)

S-core effective cross-sectional area (cm2)

According to formula 1, when the voltage U, the output voltage and the material of the transformer core are determined, the inverter frequency f is inversely proportional to the product of the number of coil turns N and the interface S of the core. When f is greatly increased, NS will be greatly reduced, and the transformer The volume and weight of the transformer will also be greatly reduced, and the volume and weight of the corresponding transformer output reactor will also be greatly reduced. Since the inverter frequency of the inverter welding power supply is much higher than the power frequency (the inverter frequency of the inverter welding power supply is generally 20KHz, and the power frequency is 50Hz), the volume and weight of the transformer of the inverter welding power supply will be greatly reduced. , the higher the inverter frequency, the more the volume and weight of the transformer will be reduced. It can be seen that the volume and weight of the transformer and reactor are greatly reduced, which will greatly reduce the volume and weight of the entire inverter welding power source itself.

The volume and weight of the transformer and reactor of the inverter welding power supply are greatly reduced, and the corresponding iron loss (core magnetic loss) and copper loss (wire loss) are also reduced; Short, the excitation current of the transformer is very small; most power switching devices work in the switching state, which consumes less power than the power devices in the working and analog states. Therefore, the inverter welding power source has high efficiency and saves electric energy. At present, most of the inverters of high-power inverter welding power sources at home and abroad adopt the full-bridge inverter mode, but the defects of this scheme are: (1) not only the driving signals of the four power switch tubes must be adjusted dynamically in real time, but also the drive The signals must be isolated from each other, the control circuit is complicated, and the reliability is low; (2) The driving signal of the power switch tube may lose wave phenomenon under light load or no-load state; (3) Four high-voltage power switch tubes are used , not only increases the manufacturing cost of the welding power source, but also causes a large power consumption.

Contents of the invention

The purpose of the present invention is to propose a new topology of the main circuit of the inverter welding power supply for the inverter welding power supply under the full-bridge inverter mode due to the simultaneous real-time control of the opening or closing of four power switch tubes. The main circuit of the welding power supply is mainly composed of two parts: the front-stage push-pull circuit inverter and the rear-stage DC chopper.

In order to achieve the above object, the present invention adopts the following technical solutions:

The high-voltage inverter low-voltage chopper welding power supply of the present invention is composed of a DC power supply connected in series with a push-pull inverter circuit, a transformer, and a full-wave rectifier circuit, wherein one output terminal of the full-wave rectifier circuit is connected to a chopper The input terminal of the full-wave rectification circuit is connected to the input terminal of the filter component on the other output terminal.

The push-pull inverter circuit is composed of two power switch tubes, IGBT1 and IGBT2, the emitters of the power switch tubes IGBT1 and IGBT2 are respectively connected to the negative pole of the DC power supply, and the collector of the power switch tube IGBT1 is connected to the same-named terminal of the primary winding of the transformer The collector of the power switch tube IGBT2 is connected to the opposite end of the primary winding of the transformer, and parasitic diodes are connected in parallel between the collectors and emitters of the power switch tubes IGBT1 and IGBT2.

The collectors and emitters of the power switch tubes IGBT1 and IGBT2 are respectively connected in parallel with RC resistance-capacitance filter networks.

The filter assembly is composed of a filter reactor L1, a freewheeling diode D3, a Hall sensor FL, and capacitors C6 and C7, wherein the input terminal of the Hall sensor FL is connected to the other output terminal of the full-wave rectification circuit, and the input terminal of the Hall sensor FL is The output terminal is respectively connected to one end of the filter reactor L1 and the anode of the freewheeling diode D3, and the cathode of the freewheeling diode D3 is respectively connected to the output terminal of the chopper and one end of the capacitor C6, and the other end of the capacitor C6 is connected to the ground with one end of the capacitor C7 , the other end of the capacitor C7 is connected to the other end of the filter reactor L1.

There are one or more sets of full-wave rectification circuits.

The advantages of the present invention are:

(1) The present invention simplifies the structure of the main circuit of the inverter welding power supply. Two high-voltage power switch tubes are omitted, and only one low-voltage power switch tube is added, which not only reduces the manufacturing cost of the inverter welding power supply, but also reduces the Change the power consumption of the welding power source.

(2) The present invention simplifies the drive circuit of the inverter welding power supply, and the drive signals of the power switch tubes of the inverter welding power supply are changed from the original mutual isolation to no need for mutual isolation, which reduces the possibility of power switch tube burnout, The working reliability and stability of the inverter welding power source are improved.

(3) The present invention simplifies the control circuit of the external characteristics of the inverter welding power supply, and the external characteristics of the inverter welding power supply are changed from controlling the opening and closing of four power switch tubes to only controlling one power switch tube The opening and closing of the inverter not only improves the reliability and stability of the inverter welding power supply, but also improves the dynamic characteristics of the inverter welding power supply.

Description of drawings

Fig. 1 main circuit diagram of the present invention.

Fig. 2 is a main circuit diagram of a full-bridge inverter welding power supply in the background technology.

Detailed ways

Below in conjunction with accompanying drawing, the technical scheme of invention is described in detail:

As shown in Figure 1, the present invention has a unique topology of the main circuit. The front stage DC 540V positive pole of the main circuit is connected to the center tap of the primary side of the main transformer, and the upper end of the primary side of the main transformer is connected to the IGBT1 collector with a withstand voltage of 1600V. The emitter of IGBT1 with a voltage value of 1600V is connected to the negative pole of DC 540V, the lower end of the primary side of the main transformer is connected to the collector of IGBT2 with a withstand voltage of 1600V, the emitter of IGBT2 with a withstand voltage of 1600V is connected to the negative pole of DC 540V, and the resistance is 10R/ One end of 2W R1 is connected to the emitter of IGBT1 with a withstand voltage of 1600V, the other end of R1 with a resistance of 10R/2W is connected to one end of C1 with a capacitance of 103/1600V, and the other end of C1 with a capacitance of 103/1600V is connected to the withstand voltage The collector of IGBT1 is 1600V. Similarly, one end of R2 with a resistance of 10R/2W is connected to the emitter of IGBT2 with a withstand voltage of 1600V, and the other end of R2 with a resistance of 10R/2W is connected to the end of C2 with a capacitance of 103/1600V. , the other end of C2 with a capacitance of 103/1600V is connected to the collector of IGBT2 with a withstand voltage of 1600V. The DC 540V of the front stage is the equivalent value of the three-phase 380V AC passing through the three-phase rectifier bridge and filter circuit, and then the DC 540V is sent to the push-pull inverter circuit. The push-pull inverter circuit includes two power switch tubes, IGBT1 and IGBT2, two sets of voltage peak absorption networks composed of R1, R2, C1 and C2, and the primary side of the transformer. The driving signals of the two power switch tubes of IGBT1 and IGBT2 are a set of two PWM waves with a fixed frequency, a fixed pulse width, and a phase difference of 180°. Due to the existence of leakage inductance on the primary side of the transformer, when the power switch tube is turned off, the IGBT collector and emitter will generate a large voltage spike, which is easy to cause damage to the power switch tube. Therefore, at the two ends of the two power switch tubes respectively An RC resistance-capacitance filter network is connected in parallel. The specific implementation process is as follows: when IGBT1 is turned on and IGBT2 is turned off, the positive pole of the previous stage passes through the center tap of the primary side of the main transformer, the upper half of the primary side of the main transformer, and then returns to the negative pole of the previous stage through IGBT1; when IGBT1 is turned off, When IGBT2 is turned on, the positive DC power of the previous stage passes through the center tap of the primary side of the main transformer, the lower half of the primary side of the main transformer, and then returns to the negative pole of the DC power of the previous stage through IGBT2, thereby inverting the DC power into a square wave AC power of a certain frequency. The frequency and duty cycle of the wave alternating current are the same as those of the PWM wave of the drive signal, and the peak voltage of the square wave alternating current is the voltage value at the positive and negative ends of the three-phase rectifier module.

As shown in Figure 1, the upper end of the secondary side of the main transformer in the rear stage of the main circuit is connected to the anode of the rectifier diode of the model D1MUR20040CT, and the cathode of the rectifier diode of the model D1MUR20040CT is connected to the collector of the IGBT3 with a withstand voltage of 600V, and the withstand voltage is 600V The emitter of the IGBT3 is connected to the positive end of the output of the welding power supply, the lower end of the secondary side of the main transformer is connected to the anode of the rectifier diode D2 of the model D1MUR20040CT, and the cathode of the rectifier diode D2 of the model D1MUR20040CT is connected to the IGBT3 with a withstand voltage of 600V The collector, the lower end of the secondary side of the main transformer is connected to one end of the output filter reactor with an inductance value of 55uH, the other end of L1 with an inductance value of 55uH is connected to the negative end of the output of the welding power supply, and the capacitance is C3 of 103/10KV One end is connected to the cathode of the rectifier diode D1 whose model is MUR20040CT, the other end of C3 with a capacitance of 103/10KV is connected to the center tap of the secondary side of the main transformer, and the end of R3 with a resistance of 10R/2W is connected to the collector of IGBT3 with a withstand voltage value of 600V Electrode, the other end of R3 with a resistance of 10R/2W is connected to one end of C4 with a capacitance of 2.2n/2KV, and the other end of C4 with a capacitance of 2.2n/2KV is connected to the center tap of the secondary side of the main transformer, the model is MUR20040CT continued The cathode of the freewheeling diode D3 is connected to the emitter of the IGBT3 with a withstand voltage of 600V, the anode of the freewheeling diode D3 of the model MUR20040CT is connected to the center tap of the secondary side of the main transformer, and the end of C6 with a capacitance of 103/10KV is connected to the output of the welding power supply The positive end, the other end of C6 with a capacitance of 103/10KV is connected to the end of C7 with a capacitance of 103/10KV, the other end of C7 with a capacitance of 103/10KV is connected to the output negative end of the welding power supply, the capacitance of C6 and the capacitance of 103/10KV The connection terminal of C7 of 103/10KV is connected to the welding power supply casing, one end of R4 with a resistance of 10R/2W is connected to the collector of IGBT3 with a withstand voltage value of 600V, and the other end of R4 with a resistance of 10R/2W is connected to a capacitance of 2.2 One end of C5 of n/2KV, the other end of C5 with a capacitance of 2.2n/2KV is connected to the emitter of IGBT3 with a withstand voltage of 600V, and the main circuit of the welding power supply passes through the induction coil of the Hall sensor FL. The latter stage is the secondary side of the main transformer, a full-wave rectifier circuit composed of D1 and D2, a filter component composed of R3, C3 and C4, a chopper IGBT3, a filter reactor L1, a freewheeling diode D3, Hall sensors FL and C6 , C7 composed of filter components. The specific realization process is as follows: the square-wave alternating current with constant frequency and constant pulse width formed by the push-pull inverter circuit on the primary side is transmitted to the secondary side through the main transformer, and then rectified into pulsating direct current through the full-wave rectifier circuit, and passed through C3, C4, R3 filters to form a smooth DC voltage, and then adjusts the duty cycle of the chopper IGBT3 drive signal in real time to adjust the effective value of the output voltage, thereby realizing the external and dynamic characteristics of the inverter welding power supply. When the chopper IGBT3 is turned off, the filter reactor L1 and the freewheeling diode D3 play a role in maintaining the continuity of the welding current.

Claims (2)

1. high-voltage inverted low-voltage chopped-mode welding power supply, it is characterized in that: the described source of welding current is connected in series successively push-pull inverter, transformer, full-wave rectifying circuit by DC power supply and consists of, the input of an output termination chopper of wherein said full-wave rectifying circuit, the input of another output termination filtering unit of full-wave rectifying circuit; Described filtering unit is made of filter reactor L1, sustained diode 3, Hall element FL and capacitor C 6, C7, another output of the input termination full-wave rectifying circuit of Hall element FL wherein, the output of Hall element FL connects respectively the end of filter reactor L1 and the anode of sustained diode 3, the negative electrode of sustained diode 3 connects respectively the output of chopper and an end of capacitor C 6, the other end of capacitor C 6 is connected ground connection with an end of capacitor C 7, the other end of another termination filter reactor L1 of capacitor C 7.

2. according to right 1 described high-voltage inverted low-voltage chopped-mode welding power supply, it is characterized in that: described push-pull inverter is made of IGBT1, two power switch pipes of IGBT2, the emitter of power switch pipe IGBT1 and IGBT2 connects respectively the negative pole of DC power supply, the collector electrode of power switch pipe IGBT1 connects the Same Name of Ends of transformer primary side winding, the collector electrode of power switch pipe IGBT2 connects the different name end of transformer primary side winding, parasitic diode in parallel respectively between the collector electrode of power switch pipe IGBT1 and IGBT2 and the emitter.

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