Semi-isolation double-inverter full-power generating electric welding machine circuit and generating electric welding machine

Abstract

The utility model discloses a semi-isolated double-inverter full-power generating electric welding machine circuit, which comprises a power unit, an inverter unit and a control unit, the power generation unit is used for converting the mechanical energy provided by the power unit into medium-frequency electric energy; wherein the two groups of filtering units are arranged in parallel and are used for filtering intermediate-frequency electric energy; the two sets of inverter units are respectively a power frequency alternating current inverter unit and an inverter welding power supply unit, the power frequency alternating current inverter unit rectifies and inverts the filtered intermediate frequency electric energy and outputs a power frequency alternating current power supply, and the inverter welding power supply unit rectifies, inverts, reduces and rectifies the filtered intermediate frequency electric energy and outputs a direct current welding power supply. According to the utility model, the bus noise can be reduced, so that the higher harmonic interference of the two sets of inversion units is reduced, the two sets of inversion units can obtain the maximum power, meanwhile, the mutual interference generated when the two sets of inversion units are used at the same time can be avoided, and the normal output of the circuit is ensured.

Description

Technical Field

[0001] The utility model relates to a power generation welding machine circuit, in particular to a semi-isolated dual-inverter full-power power generation welding machine circuit and a power generation welding machine. Background Art

[0002] As a machine integrating an engine and a welding machine, a power generation welding machine does not require an external power supply. After the engine drives the generator to generate electricity, it is directly supplied for welding use. At present, power generation welding machines are mainly used in outdoor environments without power supply or inconvenient to obtain power supply, such as maintenance, emergency, sudden rescue, and mobile operations; power generation welding machines need to have characteristics such as self-driven power generation, high efficiency, portability, reliability and stability, sufficient AC auxiliary power supply, and the ability to use welding and power generation simultaneously without interference.

[0003] Chinese patent document CN205986487U discloses a dual-motor type power generation welding machine, which includes a frame, an internal combustion engine, a permanent magnet intermediate frequency generator, an excitation power frequency induction motor, and a current regulation control system; the internal combustion engine, the permanent magnet intermediate frequency generator, and the excitation power frequency induction motor are all installed on the frame; the internal combustion engine crankshaft has an input end and an output end, the input end is connected to the permanent magnet intermediate frequency generator, and the electricity generated by the permanent magnet intermediate frequency generator is rectified by a rectification module and then connected to the current regulation control system; the output end is connected to the excitation power frequency induction motor. In the utility model, the alternating current of the permanent magnet intermediate frequency generator is rectified by a rectification module to form direct current and then provides the welding power supply of the welding machine through the control system. The output shaft of the internal combustion engine is connected to the excitation power frequency induction motor (2KW-5KW), which will provide an AC auxiliary current of 50HZ-60HZ and 110V-220V.

[0004] In this prior art, the output of direct current and alternating current is achieved by installing two motors, but there is mutual interference when outputting direct current and alternating current simultaneously, thus affecting the normal use of the power generation welding machine. Summary of the Utility Model

[0005] In order to solve the technical problem that the power generation welding machine in the prior art has mutual interference when outputting direct current and alternating current simultaneously, which affects the normal use, the utility model provides a semi-isolated dual-inverter full-power power generation welding machine circuit, including a power unit that converts internal energy into mechanical energy by burning fuel;

[0006] A power generation unit: converting the mechanical energy provided by the power unit into intermediate frequency electric energy;

[0007] Among them, there are two groups of filtering units arranged in parallel to filter the intermediate frequency electric energy;

[0008] Two sets of inverter units are arranged in parallel, namely the power frequency AC inverter unit and the inverter welding power supply unit. The power frequency AC inverter unit rectifies and inverts the filtered intermediate frequency electric energy and outputs a power frequency AC power supply, and the inverter welding power supply unit rectifies, inverts, steps down and rectifies the filtered intermediate frequency electric energy and outputs a DC welding power supply.

[0009] Compared with the prior art, in this solution, two sets of filtering units are provided to supply power to the two sets of inverter units respectively, which can reduce the bus noise, thereby reducing the high-order harmonic interference of the two sets of inverter units, and can also avoid the mutual interference generated when the two sets of inverter units are used at the same time, ensuring the normal output of the circuit.

[0010] Preferably, the filtering unit sequentially includes a three-phase star filtering capacitor, a three-phase common-mode filtering inductor and a three-phase star filtering capacitor, and the star point of the three-phase star filtering capacitor close to the inverter unit is grounded. In this solution, the three-phase star filtering capacitor can effectively absorb the voltage spikes in the three-phase circuit in the power generation unit, and the three-phase common-mode filtering inductor can effectively suppress the pulse current, and can effectively absorb the current and voltage pulses generated during the inversion process of the two sets of inverter units, thereby reducing the mutual interference when the two sets of inverter units work independently.

[0011] Preferably, both sets of inverter units are provided with rectifier filtering units. In this solution, the method of setting independent rectifier filtering units for the two sets of inverter units can effectively isolate and buffer the bus voltages of the two sets of inverter units, and effectively avoid the generation of mutual interference.

[0012] Preferably, the power frequency AC inverter unit uses asynchronous inversion when inverting the intermediate frequency electric energy. In this solution, the asynchronous inversion method of AC power generation is not limited by the power rotation speed and the motor output frequency, and can greatly release the power of the power source and the motor, which is beneficial to obtaining an abundant AC auxiliary power supply.

[0013] Preferably, the inverter welding power supply unit uses soft-switching inversion when inverting the intermediate frequency electric energy. Compared with hard switching, this solution can eliminate the overlap of voltage and current during the switching process, reduce their change rates, and thus greatly reduce or even eliminate the switching losses.

[0014] Preferably, the inverter welding power supply unit uses an IGBT switch. In this solution, the IGBT switch has low switching loss, small switching stress, high reliability, good dynamic performance, and is convenient for outputting multi-characteristic and multi-functional welding processes.

[0015] Preferably, the output ends of the two sets of inverter units are isolated by a transformer. In this solution, after the output ends are completely isolated by the transformer, the inverter units are independent of each other, further reducing the risk of mutual interference.

[0016] In a second aspect, the present utility model provides a power generation welding machine, which adopts the above-mentioned semi-isolated dual-inverter full-power power generation welding machine circuit, and the power generation unit adopts an intermediate-frequency permanent magnet alternator.

[0017] The present utility model has the following beneficial effects:

[0018] 1. Two parallel filter units supply power to two inverter units respectively, which can reduce the bus noise, thereby reducing the high-order harmonic interference of the two inverter units. While the two inverter units obtain the maximum power, they can also avoid the mutual interference generated when the two inverter units are used simultaneously, ensuring the normal output of the circuit.

[0019] 2. The inverter welding power supply unit adopts a soft-switching inverter mode, with low IGBT switching stress, small temperature rise, and high IGBT reliability. The voltage and current spikes of the IGBT switch are reduced, improving the pressure on the filter unit and the inverter unit, and reducing the mutual interference between the two inverter units.

[0020] 3. Two inverter units adopt independent rectifier units to match the energy storage and filtering combination of high-frequency low-resistance electrolytic capacitors and non-inductive thin-film capacitors. When the power generation and welding operate simultaneously under multiple working conditions, the bus voltages of the two inverter units can be effectively isolated and buffered, effectively avoiding the generation of mutual interference.

[0021] 4. The output ends of the two inverter units are isolated by a transformer, reducing the risk of mutual interference.

[0022] 5. The two inverter units of the power generation and welding dual-purpose machine adopt a semi-isolated design. The two inverter units share the winding power of the intermediate-frequency permanent magnet generator, and both can obtain full-power output. The winding manufacturing is simple, economical, and highly reliable. Description of the Drawings

[0023] Figure 1 It is the main module block diagram of an embodiment 1 of a semi-isolated dual-inverter full-power power generation welding machine circuit and a power generation welding machine according to the present utility model;

[0024] Figure 2 It is the main schematic diagram of Embodiment 1;

[0025] Figure 3 It is the main module block diagram of an embodiment 2 of a semi-isolated dual-inverter full-power power generation welding machine circuit and a power generation welding machine according to the present utility model;

[0026] Figure 4 It is the main schematic diagram of Embodiment 2;

[0027] Figure 5 It is the schematic diagram of the welding characteristic control part. Detailed Embodiment

[0028] The following is a further detailed description through specific embodiments:

[0029] 1. Definitions

[0030] Inversion: The process of converting direct current into alternating current.

[0031] Rectification: The process of converting alternating current into direct current.

[0032] Three-phase star-connected filter capacitor: Refers to a three-phase filter capacitor connected in a star configuration, where the three input terminals of the three-phase filter capacitor are respectively connected to the three phase lines of the three-phase power supply, that is, the three input terminals are connected in series.

[0033] Soft switch: It is relative to the hard switch. A soft switch is a switching process using soft switching technology. An ideal soft switching process is that the current or voltage first drops to zero, and then the voltage or current slowly rises to the off-state value, so the switching loss is approximately zero. Soft switching can achieve the high-frequency operation of power conversion devices. In a soft-switching circuit, a resonant inductor Lr and a resonant capacitor Cr are added. Compared with the filter inductor L and capacitor C, the values of Lr and Cr are much smaller. At the same time, an anti-parallel diode is added to the switch, while this diode is not required in a hard-switching circuit. In a buck-type zero-voltage-switching quasi-resonant circuit, resonance is introduced before and after the switching process, so that the voltage drops to zero before the switch is turned on, and the current drops to zero before the switch is turned off, eliminating the overlap of voltage and current during the switching process, thereby greatly reducing or even eliminating the switching loss. At the same time, the resonance process limits the rate of change of voltage and current during the switching process, reducing the switching noise.

[0034] IGBT: IGBT is the abbreviation of Insulated Gate Bipolar Transistor, which is a three-terminal semiconductor switching device and can be used for efficient and fast switching in various electronic devices.

[0035] 2. The embodiments are basically as follows: A semi-isolated dual-inversion full-power generating welding machine circuit includes a power unit that converts internal energy into mechanical energy by burning fuel; specifically, the power unit converts internal energy into mechanical energy by burning fossil fuels and provides energy output through a crankshaft.

[0036] Power generation unit: Converts the mechanical energy provided by the power unit into intermediate-frequency electrical energy; the power generation unit uses an intermediate-frequency permanent magnet alternator to convert the mechanical energy provided by the power unit into intermediate-frequency electrical energy by cutting the magnetic field.

[0037] Filtering unit, with two groups arranged in parallel, filters the intermediate-frequency electrical energy and simultaneously filters out the voltage spikes generated by the two IGBT modules during the inversion process; the filtering unit successively includes a three-phase star-connected filter capacitor, a three-phase common-mode filter inductor, and a three-phase star-connected filter capacitor, and the star point of the three-phase star-connected filter capacitor close to the inversion unit is grounded.

[0038] Two inverter units with rectifier and filter units set in parallel are respectively a power-frequency AC inverter unit and an inverter welding power supply unit. The power-frequency AC inverter unit rectifies and inverses the filtered intermediate-frequency electric energy and outputs a power-frequency AC power supply. The inverter welding power supply unit rectifies, inverses, steps down and rectifies the filtered intermediate-frequency electric energy and outputs a DC welding power supply. The output ends of the two inverter units are isolated by a transformer. Among them, the power-frequency AC inverter unit uses asynchronous inversion when inverting the intermediate-frequency electric energy, and the inverter welding power supply unit uses a soft-switching inversion mode when inverting the intermediate-frequency electric energy, specifically an IGBT switch.

[0039] This embodiment also discloses a power generation welding machine adopting the above semi-isolated double-inverter full-power generation welding machine circuit.

[0040] Embodiment 1

[0041] In this embodiment, the power generation welding machine is a 50Hz single-voltage power generation welding machine. The power unit adopts an internal combustion engine, the power generation unit adopts an intermediate-frequency permanent magnet generator, and the filtering unit is a CLC filtering unit. The inverter unit includes a power-frequency AC inverter system and a soft-switching inverter welding power supply system.

[0042] The power unit is a single or double-cylinder four-stroke gasoline / diesel unit with front and rear output shafts, which is convenient for assembling the main power generator and the auxiliary power generator.

[0043] The intermediate-frequency permanent magnet generator adopts an outer-rotor and inner-stator structure. There are 10 pairs of NS permanent magnet poles embedded on the outer rotor, specifically 20 permanent magnet blocks, including 10 N-pole magnetic blocks and 10 S-pole magnetic blocks. There are an integer multiple of 3 poles on the inner stator, such as 3*10, that is, 30 poles. After determining a starting point, every three adjacent ones are grouped into one group. The three-phase windings U, V, and W are wound around the first, second, and third poles of the first group of three poles at intervals of 120° respectively. And so on, winding around the first, second, and third poles of the second group. When all the poles of the stator are wound and the required voltage is obtained, the motor power can reach the maximum output. When the outer rotor rotates one circle, 10 positive and negative cycles will be induced on each pole winding of the stator. The rotational speed of the gasoline engine is generally 3000 - 4000 revolutions per minute. Taking 3600 revolutions per minute as an example, it rotates 3600 revolutions per minute, and the outer rotor rotates 3600 / 60 = 60 revolutions per second. The number of cycles of the induced electromotive force on the winding per second is 10*60 = 600 cycles, that is, the frequency is 600Hz; this alternating current with this frequency and voltage cannot be directly used for electric tools, nor can it be used as a welding power supply. It must be converted into 50Hz / 60Hz alternating current through the power-frequency AC inverter system, and output as a welding power supply after being converted by the welding power supply inverter system.

[0044] The power unit drives an intermediate-frequency permanent magnet alternator to output three-phase alternating current of about 400V intermediate frequency. After being filtered by the filtering unit, it is respectively supplied to the dual-inverter unit in parallel. One set of inverter unit is a power-frequency AC inverter system, providing AC power for loads such as electric tools; the other set is an inverter welding power supply unit, providing DC power for welding loads.

[0045] The two sets of inverter units are semi-isolated and share the power winding of the intermediate-frequency permanent magnet generator. Each set of inverter units can obtain the maximum power output. When only one of the two sets of inverter units is used, this set of inverter units can obtain the power output with the maximum conversion rate from the power unit. For example, if the rated power of the gasoline engine is P1, the efficiency of the motor is 0.9, the efficiency of the AC inverter in the power-frequency AC inverter system is 0.9, and the efficiency of the welding power supply in the inverter welding power supply unit is 0.83. Then the output power of the power-frequency inverter is: P1 * 0.9 * 0.9; similarly, the output power of the welding power supply is: P1 * 0.9 * 0.83.

[0046] The two sets of inverter units share the winding of the intermediate-frequency permanent magnet generator, with the highest motor utilization rate and a winding utilization rate of 100%. Compared with the isolation of the motor windings and independently supplying the power-frequency AC inverter system and the welding power supply inverter system, for example, each accounting for 50%; 50% of the motor winding power is allocated to the power-frequency AC inverter system and 50% is allocated to the welding power supply inverter system. The maximum power output of power generation is P1 * 0.5 * 0.9 * 0.9; the maximum welding output power is P1 * 0.5 * 0.9 * 0.83; for the winding sharing method, the power generation output is twice that of the independent output, and the maximum welding output is twice that of the independent winding method; when the power generation output is P1 * 0.5 * 0.9 * 0.9, only 50% of the power of the motor winding is used. At this time, the heat of the motor winding will not accumulate rapidly, the temperature rise is low, the efficiency is high, and the reliability is better. Similarly, when the welding output is P1 * 0.5 * 0.9 * 0.83, only 50% of the power of the motor winding is used, the heat of the motor winding will not accumulate rapidly, the temperature rise is low, the efficiency is high, and the reliability is better.

[0047] The two sets of inverter units share the winding of the intermediate-frequency permanent magnet generator. The motor winding is simple to manufacture, has high reliability, and is cost-effective. One set of windings, one winding method, and one output.

[0048] The industrial frequency AC inverter system rectifies, stabilizes the voltage, and filters the energy storage of the three-phase medium-frequency alternating current input by the CLC filtering unit through the combined electrolytic capacitor and non-inductive CBB film capacitor, and then inversely converts it into a power frequency 50Hz 230V or 60Hz 120 / 240V power supply for output. The CLC filtering unit consists of a three-phase star filtering capacitor, a three-phase common-mode filtering inductor, and a three-phase star filtering capacitor. The three-phase star filtering capacitor near the rectifier bridge has its star point grounded. C is a non-inductive film pulse absorption capacitor, which effectively absorbs the voltage spikes in the three-phase circuit. L is a three-phase filtering inductor, which effectively suppresses the pulse current. The CLC combination can effectively absorb the current and voltage pulses generated during the switching off of the two inverter systems, and reduce the mutual interference when the two systems work independently.

[0049] The soft-switching inverter welding power supply system rectifies the three-phase medium-frequency alternating current into a higher-ripple direct current, filters it into a low-ripple direct current through the combined electrolytic capacitor and non-inductive film capacitor for energy storage. It is then converted into a high-frequency alternating current through the inverter unit, stepped down by a high-frequency nanocrystalline core transformer, and rectified again and filtered through a reactor to output a DC power supply. The current and voltage feedback links, together with given signals such as current and voltage thrust arc starting, generate a reference voltage through PID regulation. In the PWM pulse width adjustment chip, it is compared with the peak current feedback signal pulse by pulse, and a pulse signal with an automatically adjustable width is output to drive the inverter system to work orderly, and output a steplessly adjustable DC power supply that meets the requirements of multi-characteristics and multi-functional arcs.

[0050] The two inverter units adopt independent rectifier and filter units. The control power supplies of the two inverter units are isolated, and each adopts independent feedback and PID closed-loop control, without mutual interference. The output ends are completely isolated by transformers and are independent of each other; they are separately arranged and independently installed in terms of structure, which is convenient for maintenance and repair.

[0051] Specifically, as Figure 1 and Figure 2 shown, the 50Hz single-voltage generator welding machine includes an internal combustion engine, an intermediate-frequency permanent magnet generator, a CLC filtering single voltage, an industrial frequency AC inverter system, and a soft-switching inverter welding power supply system.

[0052] The main output shaft of the internal combustion engine (front-mounted) drives the intermediate-frequency permanent magnet generator. The WindingA outputs three-phase alternating current of 420V 600Hz, namely UVW. The rear auxiliary drive shaft drives the flywheel motor. The flywheel motor includes two sets of windings, Wb and Wc. The Wb winding inputs a 12V rectification module BR1, converts and outputs 12VDC to charge the battery, and at the same time supplies power to the cooling fan FAN1 of the power devices of the soft-switching inverter welding power supply system. The Wc winding outputs double 19V alternating current, which is processed by the power part PW2 of the soft-switching inverter welding power supply system through conversion to provide ±15V DC control power for the entire soft-switching inverter welding power supply system. The control power of the soft-switching inverter welding power supply system is supplied by an independent winding, with isolated drive, and the control power is completely isolated from the industrial-frequency AC inverter system.

[0053] The three-phase alternating current of UVW of the intermediate-frequency permanent magnet generator is filtered and absorbed by the CLC filter unit 1 and then input into the industrial-frequency AC inverter system. After the three-phase alternating current of UVW is processed by the power part PW1 of the industrial-frequency inverter system through conversion and isolation, it provides various DC control powers such as +5V and ±15V for the DSP main control unit, MCU, etc. The control power of the industrial-frequency AC inverter system is completely isolated from the soft-switching inverter welding power supply system. The three-phase alternating current of UVW is rectified by the SCR1 controllable voltage-stabilizing rectifier and filtered by the combined energy storage of the C0 + C1 electrolytic capacitor and the non-inductive thin-film capacitor, and a DC voltage lower than 400V is obtained at the busbar end. The industrial-frequency AC inverter system includes the main circuit of the industrial-frequency AC inverter and the control circuit of the industrial-frequency AC inverter. The main circuit of the industrial-frequency AC inverter consists of four IGBT modules, Va, Vb, Vc, Vd, and L1, C1. The control circuit of the industrial-frequency AC inverter consists of the current-voltage feedback unit FB1 and the DSP main control unit MC0. The main control unit orderly controls the on-off of the four IGBT modules Va, Vb, Vc, Vd by modulating and matching the sine signal wave with the current-voltage feedback to obtain the sine-wave AC power supply with the desired power, frequency, and voltage. SCR1 is a thyristor component, C0 is an electrolytic capacitor, and C1 is a non-inductive thin-film capacitor. SCR1 and C0 + C1 form an independent rectification and filtering unit of the industrial-frequency AC inverter system. When the power of the welding unit or power source suddenly changes instantaneously, the single-phase conduction characteristic of the diode of SCR1 and the characteristic that the voltage of the energy storage filtering capacitor does not change play a good buffering and supporting role in stabilizing the busbar voltage, effectively reducing the risk of mutual interference when welding and power generation are used independently.

[0054] The three-phase alternating current of UVW is filtered by the CLC filter unit 2 and then input into the soft-switching inverter welding power supply system. The soft-switching inverter welding power supply system adopts a soft-switching inverter system, which consists of three parts: the welding main circuit, the welding control circuit, and the operation panel.

[0055] The main welding circuit consists of a three-phase rectifier bridge BR1, an energy storage and filtering electrolytic capacitor C00, a filtering capacitor C01, four IGBT modules V1, V2, V3, V4, absorption capacitors C4, C5, a saturation inductor L1, a resonance capacitor C3, a main transformer T1, a commutation inductor L2, a fast recovery diode assembly D1, and a DC reactor L3.

[0056] The welding control circuit consists of a main control unit MC1, a peak current sensor S1, a welding current Hall sensor S2, voltage feedback components R4, R5, C8. A resistor-capacitor absorption component R3, C6, C7 is installed at the welding output end.

[0057] The operation panel consists of a current adjustment potentiometer R6, a thrust adjustment R7, a starting arc adjustment R8, a mode selection switch SW1, a VRD switch SW2, an ammeter M1, an overheat indicator light L1, and a remote control output socket RC1. The current adjustment R6 can achieve current presetting and actual output adjustment, and fine current adjustment with a step of 1A. The ammeter displays the current preset value and the actual welding current value in real time.

[0058] The 600Hz AC power supply of three-phase UVW is absorbed and filtered by the CLC filtering unit 2, and then rectified into 560VDC by the three-phase rectifier bridge BR1. After energy storage and filtering by the high-frequency low-resistance electrolytic capacitor C00 and the non-inductive thin-film capacitor C01, a relatively stable DC power supply with low ripple is obtained at the busbar end. The IGBT modules V1, V2 are complementary conduction, and the PWM pulse width is adjustable; the IGBT modules V3, V4 are complementary conduction, and the PWM pulse width is fixed. C4, C5 are parallel capacitors for the V1, V2 modules. L1 is a saturation inductor, and C3 is a circulating current suppression capacitor (DC blocking capacitor). T1 is a nano amorphous core step-down transformer.

[0059] The four IGBT modules V1, V2, V3, V4 form a full-bridge inverter unit. V1 and V2 are complementary conduction, and V3 and V4 are complementary conduction. When V1V4 conducts, V2V3 turns off, and a +U0 positive voltage is obtained at the primary side of the main transformer T1; when V2, V3 conduct, V1, V4 turn off, and a -U0 negative voltage (U0 is the busbar voltage) is obtained at the primary side of the main transformer TI. One positive and one negative each operate once to form a complete working cycle. The PWM chip can set the working cycle duration and the inverter frequency. The inverter frequency of this machine is set at 20KHz. One working cycle is 1 / 20000 seconds = 50us. The response speed of the system to external changes can reach the microsecond level, and the dynamic response ability is fast.

[0060] By alternately operating with V1 and V4 conducting while V2 and V3 are off, and then V1 and V4 off while V2 and V3 are conducting, the DC bus voltage U0 is inverted into ±U0 between the two midpoints where the two IGBT modules intersect. Through the saturation inductor L1, the non-inductive thin-film capacitor C1 applies it to the primary side of the main transformer T1. Opposite-direction magnetic flux changes are alternately generated on the primary side of the main transformer T1, thereby inducing electromotive forces on both the primary and secondary sides of the transformer. The induced electromotive force on the primary side is equal to the bus voltage, and a low-voltage electromotive force (lower than 100V) that meets the welding requirements and conforms to the turns ratio of the T1 transformer is induced on the secondary side. After being rectified by the fast-recovery diode module D1, it is filtered by the DC reactor L3 and then output.

[0061] The welding system control unit MC1 and the operation panel output the current set signal Ig, the thrust set signal It, and the arc-starting set signal Iq. The Hall current sensor S2 converts the welding current into the If feedback voltage signal. The set signals such as Ig, It, Iq, and the If current feedback signal perform PID operations in the welding characteristic control part of the welding system control unit MC1 to form a PWM reference voltage Uref. After being sent into the current-mode PWM control chip, it is compared pulse by pulse with the peak current sensor feedback signal Ip to form a pulse signal with a corresponding width. After being frequency-divided and amplified inside the chip, two pulse signals are output, and then the adjustable pulse-width IGBT modules V1 and V2 are driven through the isolation transformer. The IGBT modules V3 and V4 do not participate in the pulse-width adjustment and receive a maximum pulse width drive except for the dead zone width. The greater the current, the higher the set voltage, the higher the corresponding PWM reference voltage, the higher the intersection point with the peak current feedback waveform, and the wider the pulse width. If the current feedback becomes smaller, the PWM reference voltage becomes higher, the pulse width becomes wider, and the output energy becomes larger, causing the output current to increase. If the current feedback becomes larger, the PWM reference voltage becomes lower, the pulse width becomes narrower, the output energy becomes smaller, and the output current decreases. The current negative feedback control enables the finally output welding current to be a fixed multiple N of the set value Ig, Io = N * Ig, realizing the constant-current characteristic output. By adjusting the Ig current set signal, stepless current adjustment can be achieved. The current negative feedback matches the PWM pulse control technology to achieve a finely adjustable constant welding current output.

[0062] The specific process of soft-switching inversion is as follows: The saturation inductor L1, resonant capacitor C3, V1, V2 and the internal diode, as well as the capacitors C4 and C5 connected in parallel at both ends, and the turn-on order of the adjustable pulse width of V1V2 and the fixed pulse width of V3V4 together constitute the soft-switching inversion. When L1 enters saturation, the inductance is very small and close to conduction. When L1 exits saturation, the inductance is very large and the loop current decays to a very small value. V1V4 receive the drive signal of MC1, and the IGBT is turned on after a time Ton1. At this time, the magnetic flux number (volt-second product) of L1 is not enough to reach saturation, and the current flowing through the IGBT and the primary side is very small. After the volt-second product Ton2 of L1 reaches the saturation point, L1 enters saturation and the current rises rapidly. Ton2 is greater than Ton1 to ensure that the IGBT realizes zero-current turn-on. When the drive signal of V1 is turned off, the current of V1 transfers to the branch of C3 connected in parallel with it, and the voltage of C3 changes linearly. V1 is basically turned off at zero voltage. The fixed maximum pulse width V4 is turned off, and the loop current flows through the saturated current of L1, and the current is very small. The fixed-pulse-width IGBTs V3 and V4 are in the state of zero (low)-current turn-on and turn-off. The adjustable-pulse-width IGBT module realizes zero-current turn-on and zero-voltage turn-off; the fixed-pulse-width IGBT module realizes zero-current turn-on and zero-current turn-off. The IGBT has small switching stress and low voltage and current spikes, reducing the pressure on the bus filtering unit and the inversion unit, and reducing the mutual interference between the two systems.

[0063] BR1 is a three-phase rectifier bridge component, C1 is an energy storage electrolytic capacitor, C2 is a non-inductive thin-film capacitor, and BR1 and C0 + C1 form an independent rectification and filtering unit of the soft-switching inversion system. When the power of the power generation unit or power source suddenly changes instantaneously, the single-phase conduction characteristic of the diode of BR1 and the characteristic that the voltage of the energy storage and filtering capacitors C1 and C2 does not change play a good buffering and supporting role in stabilizing the bus voltage of the welding unit, effectively reducing the risk of mutual interference when welding and power generation are used independently.

[0064] The three-phase 600Hz alternating current of UVW is filtered by the CLC filtering unit 2 and then rectified into 560VDC by the three-phase rectifier bridge BR1. The medium-frequency alternating current rectification can more easily obtain a bus DC voltage with small ripple. The capacitance value of the energy storage and filtering electrolytic capacitor is small, the power factor is high, the current flowing through the motor winding and the three-phase input wire is small, the heat generation is low, and the efficiency is high.

[0065] Embodiment 2

[0066] The difference from Embodiment 1 is that, as Figure 3 and Figure 4 shown, in this embodiment, the power generation welding machine is a 60Hz 120V / 240V dual-voltage power generation welding machine. The power unit uses an internal combustion engine, the power generation unit uses an intermediate-frequency permanent magnet generator, the filtering unit is a CLC filtering unit, and the inversion unit includes a power-frequency AC inversion system and a soft-switching inversion welding power supply system.

[0067] The main output shaft of the internal combustion engine (front-mounted) drives a medium-frequency permanent magnet generator. Winding A and Winding B output two sets of 260V 600Hz three-phase alternating current, U1V1W1 and U2V2W2. The front-mounted auxiliary drive shaft drives the flywheel motor, and the flywheel motor includes two sets of windings, Wc and Wd. The Wc winding inputs a 12V rectification module BR3, converts and outputs 12VDC to charge the battery, and at the same time supplies power to the heat dissipation fan FAN1 of the power devices of the soft-switching inverter welding power supply; the Wd winding outputs dual 19V alternating current, which is converted by the power supply part PW2 of the soft-switching inverter welding power supply system to provide ±15V DC control power for the entire welding system; the control power of the soft-switching inverter welding power supply system is supplied by an independent winding, isolated drive, and the control power is completely isolated from the industrial frequency inverter system.

[0068] The two-way three-phase alternating current of U1V1W1 and U2V2W2 respectively passes through the CLC filtering unit 2 and the filtering unit 1 for filtering and absorption, and then inputs two sets of industrial frequency AC inverter systems.

[0069] The alternating current of U1V1W1 is processed by the switching power supply isolation and step-down of the industrial frequency inverter system PW1 to provide various DC control powers such as +5V and ±15V for DSP, MCU, etc.; the control power of the industrial frequency inverter system is completely isolated from the welding output system; after U1V1W1 passes through SCR2 controllable voltage regulation rectification and the combined energy storage filtering of C04 + C05 electrolytic capacitors and non-inductive thin film capacitors, a DC voltage lower than 200V is obtained at the busbar end. The main circuit of the industrial frequency AC inverter consists of IGBT modules Ve, Vf, Vg, Vh and L02, C06, and the control circuit of the industrial frequency AC inverter consists of the current-voltage feedback unit FB1 and the DSP main control unit MC1. The main control unit MC1 orderly controls the on-off of the four IGBT modules Ve, Vf, Vg, Vh by modulating the sine signal wave to match the current-voltage feedback, and obtains a 120V sine wave alternating current P1 with the desired power and frequency.

[0070] Similarly, after U2V2W2 passes through SCR1 controllable voltage regulation rectification and the combined energy storage filtering of C01 + C02 electrolytic capacitors and non-inductive thin film capacitors, a DC voltage lower than 200V is obtained at the busbar end. The main circuit of the industrial frequency AC inverter consists of IGBT modules Va, Vb, Vc, Vd and L01, C03, and the control circuit of the industrial frequency AC inverter consists of the current-voltage feedback unit FB1 and the DSP main control unit MC1. The main control unit MC1 orderly controls the on-off of the four IGBTs Va, Vb, Vc, Vd by modulating the sine signal wave to match the current-voltage feedback, and obtains a 120V sine wave alternating current P2 with the desired power and frequency.

[0071] SCR1 is a thyristor component, C01 is an electrolytic capacitor, C02 is a non-inductive thin-film capacitor. SCR1 and C0 + C1 form the independent rectification and filtering unit 1 of the power frequency AC inverter system. SCR2 is a thyristor component, C04 is an electrolytic capacitor, C05 is a non-inductive thin-film capacitor. SCR2 and C04 + C05 form the independent rectification and filtering unit 2 of the power frequency AC inverter system. When there is an instantaneous power mutation in the welding unit or power source, etc., the single-phase conduction characteristics of the diodes of SCR1 and SCR2 and the characteristic that the voltage of the energy storage and filtering capacitor does not mutate play a good buffering and supporting role in stabilizing the bus voltage, effectively reducing the risk of mutual interference when welding and power generation are used independently.

[0072] The 60Hz power frequency inverter AC system is equipped with an output control unit. By switching the SW0 switch of the power generation output control unit, multiple output modes such as 120V, 240V or 120 + 240V can be realized, and the panel is matched with corresponding specification sockets.

[0073] Two-phase three-phase alternating currents of U1V1W1 and U2V2W2 are filtered by the CLC filtering unit 3 and the CLC filtering unit 4 and then input into the soft-switching inverter welding power supply system.

[0074] The soft-switching inverter welding power supply system includes three parts: a welding main circuit, a welding control circuit and an operation panel. The welding main circuit consists of a three-phase rectifier bridge BR2, a three-phase rectifier bridge BR3, an energy storage and filtering electrolytic capacitor C1, a filtering capacitor C2, IGBT inverter components V5, V6, V7, V8, absorption capacitors C4, C5, a saturation inductor L1, a resonant capacitor C3, a main transformer T1, a commutation inductor L2, a fast-recovery diode component D1, a DC reactor L3, and discharge resistors R6R7.

[0075] The welding control circuit consists of a main control unit MC2, a peak current sensor S1, a welding current Hall sensor S2, voltage feedback components R9, R10, C8. A resistor-capacitor absorption component of R8, C6, C7 is installed at the welding output end.

[0076] The operation panel consists of a current adjustment potentiometer R6, a thrust adjustment R7, an arc-start adjustment R8, a mode selection switch SW1, a VRD switch SW2, an ammeter M1, an overheat indicator light L1, and a remote control output socket RC1. The current adjustment R6 can realize current presetting and actual output adjustment. The ammeter real-time displays the current preset value and the actual welding current value.

[0077] Two three-phase alternating currents of U1V1W1 and U2V2W2 are filtered by the CLC filter unit 3 and the CLC filter unit 4 and then input into the soft-switching inverter welding power supply system. U1V1W1 is rectified into 350VDC by the three-phase rectifier bridge BR2, and U2V2W2 is rectified into 350VDC by the three-phase rectifier bridge BR3. After energy storage and filtering by the high-frequency low-resistance electrolytic capacitor C1 and the non-inductive film capacitor C2, a relatively stable DC power supply U0 with low ripple is obtained at the bus terminal. The IGBT modules V5 and V6 conduct complementarily, and the PWM pulse width is adjustable. The IGBT modules V7 and V8 conduct complementarily, and the PWM pulse width is fixed. C4 and C5 are the parallel capacitors of the IGBT modules V5 and V6. L1 is a saturation inductor, and C3 is a circulating current suppression capacitor and a DC-blocking capacitor. T1 is a nano amorphous core step-down transformer; the four IGBT modules V5, V6, V7, and V8 form a full-bridge inverter unit. The IGBT modules V5 and V6 conduct complementarily, and the IGBT modules V7 and V8 conduct complementarily. When the IGBT modules V5 and V8 conduct, the IGBT modules V6 and V7 are turned off, and the primary side of the main transformer TI obtains a +U0 positive voltage; when the IGBT modules V6 and V7 conduct, the IGBT modules V5 and V8 are turned off, and the primary side of the main transformer TI obtains a -U0 negative voltage (U0 is the bus voltage); one positive and one negative each operate once to form a complete working cycle. The PWM chip can set the working cycle duration and the inverter frequency. The inverter frequency of this machine is set at 20KHz. A working cycle is 1 / 20000 seconds = 50us. The response speed of the system to external changes can reach the microsecond level, and the dynamic response ability is fast.

[0078] By turning on the IGBT modules V5 and V8 and turning off the IGBT modules V6 and V7, and turning off the IGBT modules V5 and V8 and turning on the IGBT modules V6 and V7, and operating alternately, the bus DC voltage U0 is inverted into ±U0 between the two midpoints where the two IGBT modules intersect. Through the saturation inductor L1 and the non-inductive film capacitor C1, it is applied to the primary side of the main transformer T1, and magnetic flux changes in opposite directions are alternately generated on the primary side of the main transformer T1, thereby inducing electromotive forces on the primary and secondary sides of the transformer. The induced electromotive force on the primary side is equal to the bus voltage, and a low-voltage electromotive force (lower than 100V) that meets the welding requirements and conforms to the turns ratio of the T1 transformer is induced on the secondary side. After rectification by the fast recovery diode module D1 and filtering by the DC reactor L3, it is output.

[0079] The welding system control unit MC2. The operation panel realizes the output of the current given signal Ig, the thrust given signal It, and the arc starting given signal Iq. The Hall current sensor S2 converts the welding current into an If voltage signal. The Ig, It, Iq given signals and the If current feedback signal perform PID operations in the welding characteristic control part within MC2 to form a PWM reference voltage Uref, which is sent into the current-mode PWM control chip and compared pulse by pulse with the peak current sensor feedback signal Ip to form pulse signals with corresponding widths. After being frequency-divided and amplified inside the chip, two-way pulse signals are output, and then the IGBT modules V5 and V6 with adjustable PWM pulse widths are driven through an isolation transformer; the IGBT modules V7 and V8 do not participate in the PWM pulse width adjustment. The IGBT modules V7 and V8 obtain a maximum pulse width drive that maintains the same phase relationship as the IGBT modules V5 and V6 except for the dead zone width; the larger the current, the higher the given voltage of Ig, the corresponding increase in the PWM reference voltage, the higher the intersection point of the peak current feedback waveform, and the wider the pulse width; if the current feedback becomes smaller, the PWM reference voltage becomes higher, the pulse width becomes wider, the output energy becomes larger, and the output current becomes larger; if the current feedback becomes larger, the PWM reference voltage becomes lower, the pulse width becomes narrower, the output energy becomes smaller, and the output current becomes smaller; the current negative feedback control makes the finally output welding current equal to N times the given value Ig, Io = N * Ig, realizing the constant current characteristic output. By adjusting the Ig current given signal, that is, by adjusting the R6 current potentiometer on the panel, stepless current adjustment can be achieved; the current negative feedback matches the PWM pulse control technology to realize the fine-adjustable constant welding current output, with a wide current output range and strong adaptability.

[0080] The soft-switching inverter process is the same as the 50Hz soft-switching inverter process in Embodiment 1.

[0081] BR2 and BR3 are three-phase rectifier bridge components, C1 is an energy storage electrolytic capacitor, and C2 is a non-inductive film capacitor. BR2, BR3 and C1 + C2 form an independent rectification and filtering unit of the soft-switching inverter system. When there are sudden power mutations in the power generation unit or power source, etc., the single-phase conduction characteristics of the diodes of BR2 and BR3 and the voltage non-mutation characteristics of the C1 and C2 energy storage and filtering capacitors play a good buffering and supporting role in stabilizing the bus voltage of the welding unit, effectively reducing the risk of mutual interference when welding and power generation are used independently.

[0082] The three-phase 600Hz alternating current of U1V1W1 and U2V2W2 is absorbed and filtered by the CLC filter unit 3 and the filter unit 4, and then rectified into 350VDC by the three-phase rectifier bridges BR2 and BR3. The medium-frequency 600Hz alternating current rectification makes it easier to obtain a bus DC voltage with small ripple. The capacitance value of the energy storage filtering electrolytic capacitor is small, the power factor is high, the current flowing through the motor winding and the three-phase input wire is small, the heat generation is low, and the efficiency is high.

[0083] In Embodiment 1 and Embodiment 2, the welding characteristic control section in the welding system control unit MC1 is as follows Figure 5 as shown. The welding characteristic control section consists of six parts: current determination unit 1, current determination unit 2, voltage determination unit 1, voltage determination unit 2, current comprehensive setting unit, and PID operation and output unit.

[0084] Current determination unit 1 consists of comparator COMP1. Current determination unit 1 determines the presence or absence of welding current and outputs the corresponding Ip1, which is used to control the turning on or off of electronic switch SW2 and the turning on or off of electronic switch SW4; when the welding current is 0, If is 0, Ug3 is greater than If, Ip1 outputs a high potential, enabling electronic switch SW1, and the starting arc current Iq is added to the comprehensive setting; when there is an output of welding current, Ug3 is less than If, Ip1 outputs a low potential, electronic switch SW1 is disconnected, and the starting arc current Iq exits the comprehensive setting.

[0085] Current determination unit 2 consists of comparator COMP2, resistor R6, and triode T1. Current determination unit 2 is used to set the maximum welding current; the given value Ug4 corresponds to Ifmax. When If is less than the Ifmax current, Ip2 is at a low potential; when If is greater than the Ifmax current, Ip2 outputs a high potential, driving triode T1 to saturation through R6, Uref is 0, and there is no PWM output; thus, the maximum current is limited.

[0086] Voltage determination unit 1 consists of comparator COMP3 and mode switch SW1. Voltage determination unit 1 sets the thrust given threshold for different welding modes. For different welding modes, Ug1 is different. When the arc voltage Uf is lower than Ug1, Up1 outputs a high potential, enabling electronic switch SW3, and the thrust current It is added to the comprehensive setting; when the arc voltage Uf is greater than Ug1, the output of Up1 is 0, electronic switch SW3 is disconnected, and the thrust current It exits the comprehensive setting.

[0087] Voltage determination unit 2 consists of comparator COMP4, electronic switch SW4, resistor R7, and triode T2. When voltage determination unit 2 is working, it sets the upper limit value of the arc voltage; when not welding, Ip1 is at a high potential, electronic switch SW4 of SW4 is disconnected, and Up2 does not affect the Uref output; after the welding current is established, Ip1 is at a low potential, electronic switch SW4 of SW4 is closed, Up2 acts on T2 through R7, Ug2 is the upper limit value of the arc voltage Ufmax. When Uf is lower than Ug2, Up2 is 0, T2 is cut off, and Uref is normally output; when Uf is higher than Ug2, Up2 is at a high potential, T2 is saturated and conducting, Uref is 0, and there is no PWM output, realizing the setting of the upper limit value of the arc voltage, preventing the arc from burning with excessive power, and ensuring smooth arc extinguishing.

[0088] The integrated current setting unit consists of electronic switch SW2, electronic switch SW3, resistors R1, R2, R3, and integrated operational amplifier AMP1. When the integrated current setting unit works, it performs an integrated summation operation on the welding current setting Ig, the thrust current setting It, and the starting arc current setting Iq, and outputs the integrated current setting Ig1 to the PID operation unit. Ig is the basic current setting value, and Iq is the starting arc current setting value (default is 0 in TIG mode, without the starting arc function). When the welding current is 0, Ip1 is at a high potential to enable SW2 to conduct, and the starting arc current Iq is added to the integrated operational amplifier. Ig1 = N*(Ig + Iq). The current at the moment of starting the arc is greater than the base value setting Ig, greatly improving the arc starting success rate. During the welding process, when the arc voltage Ug is lower than Ug1, Up1 outputs a high potential to enable SW3 to conduct, and the thrust current It is added to the integrated operation. Ig1 = N*(Ig + It). When performing short arc operation or when the arc voltage changes suddenly, the welding current increases adaptively to ensure that the arc is stable and does not stick to the electrode.

[0089] The PID operation and output unit consists of integrated operational amplifier AMP2, resistors R4, and R5. The integrated operational amplifier performs PID operation on the current setting Ig1 and the current negative feedback If, and outputs Uref to the PWM control module after voltage division by R4 and R5.

[0090] The above are only embodiments of the present invention. Specific structures and common knowledge such as characteristics well known in the art are not described in detail herein. Those of ordinary skill in the art know all the common general technical knowledge in the technical field to which the present invention belongs before the filing date or the priority date, can know all the existing technologies in this field, and have the ability to apply conventional experimental means before this date. Those of ordinary skill in the art can, under the inspiration given in this application, combine their own abilities to improve and implement this solution. Some typical well-known structures or well-known methods should not become obstacles for those of ordinary skill in the art to implement this application. It should be noted that for those skilled in the art, without departing from the structure of the present invention, several deformations and improvements can be made, and these should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent. The protection scope required by this application should be based on the content of its claims, and the specific implementation manners described in the specification can be used to interpret the content of the claims.

Claims

1. A semi-isolated double-inverter full-power generating welding machine circuit, comprising a power unit that converts internal energy into mechanical energy by burning fuel; A generating unit: converts the mechanical energy provided by the power unit into intermediate-frequency electrical energy; It is characterized in that: A filtering unit, with two sets arranged in parallel, for filtering the intermediate-frequency electrical energy; Two sets of inverter units arranged in parallel, namely a power-frequency AC inverter unit and an inverter welding power supply unit. The power-frequency AC inverter unit rectifies and inverts the filtered intermediate-frequency electrical energy and outputs a power-frequency AC power supply, and the inverter welding power supply unit rectifies, inverts, steps down and rectifies the filtered intermediate-frequency electrical energy and outputs a DC welding power supply.

2. The semi-isolated dual-inverter full-power generating electric welding machine circuit according to claim 1, characterized in that: The filtering unit sequentially includes a three-phase star-connected filtering capacitor, a three-phase common-mode filtering inductor and a three-phase star-connected filtering capacitor, and the star point of the three-phase star-connected filtering capacitor close to the inverter unit is grounded.

3. The semi-isolated dual-inverter full-power welding generator circuit according to claim 2, wherein: Both sets of inverter units are provided with a rectifying and filtering unit.

4. The semi-isolated dual-inverter full-power generating welding machine circuit according to any one of claims 1-3, characterized in that: The power-frequency AC inverter unit uses asynchronous inversion when inverting the intermediate-frequency electrical energy.

5. The semi-isolated dual-inverter full-power welding generator circuit according to claim 4, wherein: The inverter welding power supply unit uses soft-switching inversion when inverting the intermediate-frequency electrical energy.

6. The semi-isolated dual-inverter full-power generating welding machine circuit according to claim 5, characterized in that: The inverter welding power supply unit uses IGBT switches.

7. The semi-isolated dual-inverter full-power welding generator circuit according to claim 6, characterized in that: The output ends of the two sets of inverter units are isolated by a transformer.

8. A power generation welding machine, characterized in that: Adopt the semi-isolated double-inverter full-power generating welding machine circuit according to any one of claims 1-7; the generating unit adopts an intermediate-frequency permanent magnet AC generator.

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