A buck pre-regulation linear variable polarity micro-welding power supply and a method of using the same

Abstract

The application discloses a Buck pre-stabilization linear variable-polarity micro-welding power supply and a use method thereof, and relates to the technical field of embedded closed-loop control. The Buck pre-stabilization linear variable-polarity micro-welding power supply comprises a direct-current input end, a pre-stabilization module, a linear regulation module, a variable-polarity output module, a detection module and a control module, wherein the direct-current input end is connected with the pre-stabilization module, the pre-stabilization module is connected with the linear regulation module, the linear regulation module is connected between the pre-stabilization module and the variable-polarity output module, the variable-polarity output module is connected with the linear regulation module, and the detection module is connected with the variable-polarity output module, the pre-stabilization module and the control module respectively. The Buck pre-stabilization linear variable-polarity micro-welding power supply can improve the controllability and consistency of a micro-welding process.

Description

Technical Field

[0001] This invention relates to the field of embedded closed-loop control technology, and in particular to a Buck pre-regulated linear variable polarity microwire welding power supply and its usage method. Background Technology

[0002] Micro-wires, terminal leads, and enameled wires are suitable for welding due to their small heat capacity, small contact area, and narrow welding window. Existing micro-welding power supplies typically use capacitor discharge, thyristor AC power regulation, intermediate frequency inverters, or single switching power supplies to achieve energy output. Some systems also use parameters such as pulse amplitude, pulse width, preheating stage, and main welding stage for welding process control. While these solutions can meet the needs of general spot welding or wire welding, they are still prone to problems such as large output ripple, transient overshoot, unilateral overheating, uneven local melting of solder joints, and concentrated heat generation from power devices in micro-wire scenarios. Summary of the Invention

[0003] To address the aforementioned technical problems, the present invention aims to provide a Buck pre-regulated linear variable polarity microwire welding power supply and its usage method, which can improve the controllability and consistency of the micro-welding process.

[0004] The first technical solution adopted in this invention is: a Buck pre-regulated linear variable polarity microwire welding power supply, comprising a DC input terminal, a pre-regulated module, a linear adjustment module, a variable polarity output module, a detection module, and a control module, wherein: The DC input terminal is connected to the pre-regulator module and is used to provide DC input power to the pre-regulator module; The pre-regulator module is connected to the linear regulator module and is used to step down and regulate the DC input power to generate a pre-regulated voltage. The pre-regulated voltage is adjusted according to the first control signal output by the control module so that the linear regulator module is within a preset voltage drop range. The linear adjustment module is connected between the pre-stabilized voltage module and the variable polarity output module, and is used to finely adjust the pre-regulated voltage according to the second control signal output by the control module to generate the target welding output voltage or the target welding output current. The variable polarity output module is connected to the linear adjustment module and is used to change the welding output polarity according to the direction control signal output by the control module to form a positive welding output or a reverse welding output. The detection module is connected to the variable polarity output module, the pre-stabilized voltage module and the control module respectively, and is used to collect welding output current data, welding output voltage data and pre-stabilized voltage data; The control module is used to generate the first control signal, the second control signal, and the direction control signal based on the welding output current data, the welding output voltage data, and the pre-stabilized output voltage data, so as to control the pre-stabilized module, the linear adjustment module, and the variable polarity output module to work together to realize constant current control, constant voltage control, constant power control, and variable polarity control in the microwire welding process.

[0005] Furthermore, the pre-regulator module includes a Buck step-down circuit, switching devices, and a PWM drive circuit, wherein: The PWM drive circuit is connected to the control module and is used to generate a PWM drive signal according to the first control signal and send it to the switching device to adjust the output voltage of the Buck step-down circuit.

[0006] Furthermore, the control module calculates the voltage drop margin of the linear adjustment module based on the voltage difference between the pre-regulated output voltage data and the welding output voltage data, and generates the first control signal based on the voltage drop margin to make the linear adjustment module work in a preset low voltage drop state.

[0007] Furthermore, the detection module includes a welding current sampling unit, a welding voltage sampling unit, and a pre-regulated voltage sampling unit, wherein: The welding current sampling unit is used to acquire welding current feedback data; The welding voltage sampling unit is used to acquire welding voltage feedback data; The pre-regulated voltage sampling unit is used to acquire the pre-regulated voltage feedback data.

[0008] Furthermore, the control module includes a waveform generation unit, a closed-loop adjustment unit, and a protection unit, wherein: The waveform generation unit is used to generate constant current waveforms, constant voltage waveforms, constant power waveforms, sinusoidal pulsating waveforms, or sawtooth pulsating waveforms according to preset welding parameters. The closed-loop adjustment unit is used to adjust the output of the linear adjustment module based on the data fed back by the detection module. The protection unit is used to perform protection control based on abnormal current data, abnormal voltage data, or abnormal power data collected by the detection module.

[0009] The second technical solution adopted in this invention is: a method for using a Buck pre-regulated linear variable polarity microwire welding power supply, comprising the following steps: Acquire welding output current data, welding output voltage data, and pre-regulated output voltage data; The voltage drop margin of the current linear adjustment module is calculated based on the pre-regulated output voltage data and the welding output voltage data. First adjustment data is generated based on the difference between the voltage drop margin and the preset voltage drop target value, and a PWM control signal is generated based on the first adjustment data; The output voltage of the pre-regulator module is adjusted according to the PWM control signal so that the voltage drop margin of the linear adjustment module is within a preset range. Target output data is generated based on welding process parameters, and second control data is generated based on the deviation between the target output data and the welding output current data or the welding output voltage data. Adjust the output of the linear adjustment module according to the second control data so that the welding output meets the target welding parameters.

[0010] Furthermore, the step of generating target output data based on welding process parameters specifically includes: Read the preset welding recipe data; The output mode, output amplitude, duration, and frequency parameters corresponding to the current welding stage are determined based on the welding recipe data. Based on the output mode, generate the corresponding target current data, target voltage data, or target power data.

[0011] Furthermore, it also includes: The current welding stage is determined based on the welding formula data and cumulative welding time. Acquire the target waveform data corresponding to the current welding stage, and generate target output data based on the target waveform data; The target output data is compared with the acquired welding output current data or welding output voltage data to obtain the output deviation data; The second control data is updated based on the output deviation data, and the updated second control data is sent to the linear adjustment module so that the linear adjustment module outputs a welding waveform corresponding to the current welding stage.

[0012] Furthermore, it also includes: Calculate the dynamic resistance data based on the welding output voltage data and the welding output current data; The dynamic resistance data is filtered to obtain dynamic resistance change data; The dynamic resistance change data is compared with a preset dynamic resistance threshold to obtain the welding status judgment result; Adjust the target output data or the second control data according to the welding status judgment result; The linear adjustment module outputs welding current based on the adjusted second control data to achieve weld nugget formation judgment and abnormal state protection during the welding process.

[0013] Furthermore, it also includes: Generate commutation control data based on the polarity control parameters in the target output data; The polarity switching time is determined based on the commutation control data, and the commutation condition is determined based on the current welding output current data. When the commutation condition is met, a polarity switching control signal is generated, causing the variable polarity output module to switch the output direction. After completing the polarity switch, the second control data is regenerated based on the target output data, and the linear adjustment module is controlled to restore the target welding output.

[0014] The beneficial effects of this invention are as follows: The Buck stage handles coarse adjustment and efficiency improvement, while the linear stage handles the final fine adjustment of the micro-welding current, avoiding direct input of simple switching power supply ripple to the solder joint. For micro-wires with small heat capacity and narrow welding windows, it can achieve programmable outputs with multiple amplitudes, sinusoidal or sawtooth pulsations under low ripple conditions. The subsequent H-bridge allows the welding current to alternate between forward and reverse directions at a set frequency, reducing electrode bias, heat bias, and the tendency for local overmelting under long-term single-polarity operation. Compared with ordinary fixed DC output, this structure is suitable for more balanced control of the heat distribution on both sides of the micro-wire solder joint. By first reducing the DAC output and turning off the H-bridge before commutation, a low-current commutation dead zone is formed before forward and reverse switching, reducing the risk of bridge arm shoot-through, current spikes, and instantaneous impact on the solder joint. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structural framework of a Buck pre-regulated linear variable polarity microwire welding power supply according to the present invention; Figure 2 This is a flowchart illustrating the steps of using a Buck pre-regulated linear variable polarity microwire welding power supply according to the present invention. Figure 3 This is a schematic diagram of the Buck pre-regulated linear fine-tuning and H-bridge main circuit topology provided in a specific embodiment of the present invention; Figure 4 This is a schematic diagram of the synchronous sampling and closed-loop control process provided in a specific embodiment of the present invention; Figure 5 This is a schematic diagram of the low-current commutation timing of a variable polarity H-bridge provided in a specific embodiment of the present invention; Figure 6 This is a schematic diagram of the multi-segment programmable welding recipe execution process provided in a specific embodiment of the present invention; Figure 7 This is a schematic diagram of the Q-Stop dynamic resistor-assisted soldering stop protection process provided in a specific embodiment of the present invention; Figure 8 This is a schematic diagram of the system operation interface provided in a specific embodiment of the present invention. Detailed Implementation

[0016] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The step numbers in the following embodiments are only for ease of explanation and do not limit the order of the steps. The execution order of each step in the embodiments can be adapted according to the understanding of those skilled in the art.

[0017] First, it should be noted that in related technologies, for example: 1) Microwire or enameled wire welding device, the focus is on electrode structure, welding head pressure mechanism, pulse amplitude and pulse width preset circuit, etc., and the composite power supply structure of Buck follower linear fine adjustment stage voltage drop is not disclosed.

[0018] 2) Variable polarity micro-resistance spot welding power supply, specifically a variable polarity micro-resistance spot welding power supply based on capacitor fast charge and discharge control. Its focus is on capacitor charge and discharge and variable polarity output mode. The subsequent H-bridge is not used as the commutation unit after linear fine-tuning. It forms a unified closed loop with Buck pre-regulation, linear stage voltage drop follower, and timer-triggered ADC / DMA sampling.

[0019] 3) The welding polarity switching device has an electronic commutation structure that selects the output polarity according to the process. However, it belongs to the polarity configuration of multi-process welding power supply and does not propose Buck-linear composite control to address the contradiction between low ripple linear output and heat dissipation of linear devices in micro-wire welding.

[0020] 4) Dynamic resistance and weld nugget quality detection schemes, such as the research on adaptive control of resistance spot welding based on dynamic resistance model, show that the use of dynamic resistance for welding quality tracking and control is a relatively common approach.

[0021] 5) According to general resistance welding power supply product data, high-frequency inverter, linear DC, capacitor discharge and AC power supplies can all be used for different resistance welding applications, but they are usually implemented separately according to power supply type. Buck pre-regulation, linear fine adjustment, post-stage polarity change and synchronous sampling control are rarely designed as an overall structure for micro-wire welding.

[0022] The related technologies have the following technical problems: While simple linear welding power supplies offer low output ripple and fine-tuning, significant voltage drops and heat dissipation on the linear regulating transistor or MOSFET can occur when the input voltage differs greatly from the welding output voltage. This can lead to overheating during continuous or repeated welding, affecting stability. Simple Buck or inverter welding power supplies offer high efficiency, but high-frequency switching ripple, sampling phase inconsistencies, and sudden load changes can degrade the fine-tuning control of micro-welding current. Ordinary H-bridge polarity-changing outputs can change the current direction, but if the output current does not decay in advance during commutation, spikes, bridge arm impacts, or localized overheating of the solder joint can easily occur. Existing multi-segment waveform control focuses primarily on the shape of the welding current itself, rarely integrating the buck pre-regulated linear transistor voltage drop control, linearly fine-tuned DAC output, H-bridge low-current commutation, and synchronous ADC / DMA feedback into a unified design. Therefore, a composite power supply structure and control method for micro-wire welding is needed, which can reduce the heat dissipation of linear devices while retaining the fine-tuning capability of linear output, and improve localized overmelting and unidirectional thermal bias problems through controlled polarity changes.

[0023] Based on this, this invention addresses the challenges of balancing high-precision output and low heat generation in micro-wire welding, the difficulty in simultaneously controlling switching power supply ripple and linear power supply heat dissipation, the potential for current surges due to polarity-changing commutation, and the asynchrony between welding waveform and sampling feedback. It proposes a Buck pre-regulated linear variable polarity micro-wire welding power supply and control system. This system provides appropriate margin for the linear fine-tuning stage through pre-stage Buck follower adjustment, outputs precise welding control quantities through the linear stage, and achieves alternating forward and reverse energization through a subsequent H-bridge. Furthermore, it coordinates Buck PWM, ADC-triggered sampling, DMA transfer, closed-loop control, and commutation dead zone using the same high-speed timing reference, thereby improving the controllability and consistency of the micro-welding process.

[0024] Reference Figure 1 The present invention provides a Buck pre-regulated linear variable polarity microwire welding power supply, including a DC input terminal, a pre-regulated module, a linear adjustment module, a variable polarity output module, a detection module, and a control module.

[0025] In this embodiment, the system includes a DC input terminal, a Buck step-down pre-regulator stage, a linear fine-tuning stage, a variable polarity H-bridge output stage, a welding current sampling unit, a welding voltage sampling unit, a Buck output voltage sampling unit, an embedded control unit, a human-machine interface unit, and a recipe storage unit. The DC input terminal is connected to the Buck step-down pre-regulator stage. The output terminal of the Buck step-down pre-regulator stage is connected to the linear fine-tuning stage. The output terminal of the linear fine-tuning stage is connected to the variable polarity H-bridge output stage. The variable polarity H-bridge output stage is connected to the welding electrode or microwire clamp. The welding current sampling unit, the welding voltage sampling unit, and the Buck output voltage sampling unit respectively feed back the sampled signals to the embedded control unit.

[0026] The DC input terminal is connected to the pre-regulator module and is used to provide DC input power to the pre-regulator module; The pre-regulator module is connected to the linear regulator module and is used to step down and regulate the DC input power to generate a pre-regulated voltage. The pre-regulated voltage is adjusted according to the first control signal output by the control module so that the linear regulator module is within a preset voltage drop range. The pre-regulator module includes a Buck step-down circuit, a switching device, and a PWM drive circuit. The PWM drive circuit is connected to the control module and is used to generate a PWM drive signal according to the first control signal and send it to the switching device to adjust the output voltage of the Buck step-down circuit.

[0027] Specifically, the Buck step-down pre-regulator stage is used to perform high-frequency step-down pre-regulation of the DC input and provide the linear fine-tuning stage with an intermediate bus voltage that can follow the changes; its control terminal is connected to the PWM output terminal of the embedded control unit, and its feedback terminal is connected to the ADC sampling channel through the Buck output voltage sampling unit.

[0028] The linear adjustment module is connected between the pre-stabilized voltage module and the variable polarity output module, and is used to finely adjust the pre-regulated voltage according to the second control signal output by the control module to generate the target welding output voltage or the target welding output current. Specifically, the linear fine-tuning stage is connected between the Buck step-down pre-regulator stage and the variable polarity H-bridge output stage, and is used to perform low ripple and fine-grained adjustment of the welding output; its control terminal receives the DAC analog output of the embedded control unit, and its output terminal is connected to the H-bridge input terminal.

[0029] The variable polarity output module is connected to the linear adjustment module and is used to change the welding output polarity according to the direction control signal output by the control module to form a positive welding output or a reverse welding output. Specifically, the variable polarity H-bridge output stage is connected after the linear fine-tuning stage and is used to output the linearly fine-tuned welding energy as a forward or reverse welding current according to a set timing sequence; its direction control terminal and enable terminal are respectively connected to the GPIO control terminal of the embedded control unit.

[0030] The detection module is connected to the variable polarity output module, the pre-stabilized voltage module and the control module respectively, and is used to collect welding output current data, welding output voltage data and pre-stabilized voltage data; The detection module includes a welding current sampling unit, a welding voltage sampling unit, and a pre-regulated voltage sampling unit. The welding current sampling unit is used to acquire welding current feedback data; the welding voltage sampling unit is used to acquire welding voltage feedback data; and the pre-regulated voltage sampling unit is used to acquire the pre-regulated voltage feedback data.

[0031] Specifically, the welding current sampling unit is connected in series or coupled in the welding circuit to obtain welding current feedback; the welding voltage sampling unit is connected in parallel or in a voltage divider connection to the welding output terminal to obtain welding end voltage feedback; and the Buck output voltage sampling unit is connected to the Buck output terminal to calculate the voltage drop margin of the linear fine-tuning stage.

[0032] The control module is used to generate the first control signal, the second control signal, and the direction control signal based on the welding output current data, the welding output voltage data, and the pre-stabilized output voltage data, so as to control the pre-stabilized module, the linear adjustment module, and the variable polarity output module to work together to realize constant current control, constant voltage control, constant power control, and variable polarity control in the microwire welding process.

[0033] The control module calculates the voltage drop margin of the linear adjustment module based on the voltage difference between the pre-regulated output voltage data and the welding output voltage data, and generates the first control signal based on the voltage drop margin to make the linear adjustment module work in a preset low voltage drop state.

[0034] The control module includes a waveform generation unit, a closed-loop adjustment unit, and a protection unit. The waveform generation unit is used to generate constant current waveforms, constant voltage waveforms, constant power waveforms, sinusoidal pulsating waveforms, or sawtooth pulsating waveforms based on preset welding parameters. The closed-loop adjustment unit is used to adjust the output of the linear adjustment module based on the data fed back by the detection module. The protection unit is used to perform protection control based on abnormal current data, abnormal voltage data, or abnormal power data collected by the detection module.

[0035] Specifically, the embedded control unit is used to uniformly generate Buck PWM, DAC control signals, and H-bridge direction control signals, and synchronously acquires welding current, welding voltage, and Buck output voltage via ADC and DMA. This control unit also performs multi-segment waveform generation, closed-loop control, polarity commutation, and fault protection based on recipe parameters. The human-machine interface unit is connected to the embedded control unit and is used to set the welding segment type, amplitude, time, frequency, polarity commutation enable, and Q-Stop enable; the recipe storage unit is connected to the embedded control unit and is used to save and load multi-segment welding recipes.

[0036] Furthermore, the control unit calculates the voltage drop margin of the linear adjustment stage based on the difference between the Buck output voltage and the welding output voltage, and adjusts the Buck PWM duty cycle through the Buck outer loop PID to maintain the linear adjustment stage within the set low voltage drop operating range. For example, the voltage drop margin can be maintained near the target of approximately 400 corresponding to the ADC sampling value. In practical engineering, this can be converted into a linear adjustment margin of several hundred millivolts to several volts according to the sampling ratio. This prevents the linear device from being subjected to excessively high voltage drops for extended periods.

[0037] The control unit generates a target current or target waveform based on the welding recipe and outputs an analog control quantity to the linear fine-tuning stage via a DAC. The linear fine-tuning stage can operate in constant current, constant voltage, constant power, sinusoidal pulsation, and sawtooth pulsation modes; among them, the constant current, constant voltage, and constant power modes can use incremental PID closed loop, while the sinusoidal and sawtooth modes can generate the target amplitude by looking up a table or phase accumulation.

[0038] Reference Figure 2 A method for using a Buck pre-regulated linear variable polarity microwire welding power supply includes: S100: Acquire welding output current data, welding output voltage data, and pre-regulated output voltage data; S200. Calculate the current voltage drop margin of the linear adjustment module based on the pre-regulated output voltage data and the welding output voltage data. S300: Generate first adjustment data based on the difference between the voltage drop margin and the preset voltage drop target value, and generate a PWM control signal based on the first adjustment data; S400. Adjust the output voltage of the pre-stabilized voltage module according to the PWM control signal so that the voltage drop margin of the linear adjustment module is within a preset range; S500: Generate target output data based on welding process parameters, and generate second control data based on the deviation between the target output data and the welding output current data or the welding output voltage data; S600. Adjust the output of the linear adjustment module according to the second control data so that the welding output meets the target welding parameters.

[0039] In this embodiment, firstly, after the system is powered on, the Buck PWM, DAC, ADC, DMA, H-bridge GPIO, human-machine interface unit, and recipe storage unit are initialized, and the Buck duty cycle, DAC output, and H-bridge enable signal are set to a safe off state. Then, multiple welding recipes and polarity parameters are read from the recipe storage unit; if no valid recipe is read, a default recipe is loaded and written to the recipe storage unit. After welding starts, a timer generates Buck PWM, and the timer update event triggers multi-channel synchronous sampling of the ADC. The ADC sequentially collects welding current, welding voltage, and Buck output voltage, and the DMA transfers the sampling results to a high-speed buffer. Further, the control unit executes a high-speed control loop according to a predetermined frequency division, performs first-order smoothing filtering on the current sampling value, and locates the current welding segment based on the accumulated welding time, reading the waveform type, amplitude, duration, and frequency of the current welding segment. The control unit then generates a target output value based on the current welding segment. For constant current, constant voltage, and constant power segments, a corresponding closed-loop target is generated. For sinusoidal or sawtooth segments, the instantaneous target amplitude is generated through phase accumulation and table lookup. The control unit calculates the difference between the Buck output voltage and the welding output voltage to obtain the current voltage drop margin of the linear fine-tuning stage, and compares it with the target voltage drop margin. The Buck PWM duty cycle is updated through the Buck outer loop PID. The control unit compares the target output value with the current or voltage feedback, and updates the DAC control quantity through the linear stage closed-loop algorithm or waveform direct output algorithm to make the linear fine-tuning stage output a low-ripple welding control quantity. When polarity change is enabled, the control unit calculates the forward and reverse commutation period based on the polarity change frequency. In the dead zone before commutation, the DAC output is first reduced to zero or a safe low value, and the H-bridge output is turned off. After the current decays, the forward and reverse conduction states of the H-bridge are switched. Finally, the control unit records the welding current, voltage, power, or dynamic resistance curve, and performs overcurrent, overvoltage, temperature, and Q-Stop protection checks; when all welding segments are completed or protection conditions are triggered, the Buck PWM, DAC output, and H-bridge output are turned off.

[0040] In addition, the system can be set to provide auxiliary dynamic resistance welding stop protection. The control unit calculates the equivalent dynamic resistance based on the welding voltage and welding current, performs low-pass smoothing on it, and records the peak resistance during the welding process; when the dynamic resistance relative to the peak value continues to drop below a preset ratio, it is determined that the risk of weld nugget formation or overmelting has increased, triggering a prompt or stopping the output.

[0041] The present invention will be explained and described in conjunction with specific embodiments: Specific Implementation Example 1: The overall structure of Buck pre-stabilization, linear fine-tuning, and H-bridge polarity change.

[0042] In this embodiment, the DC input first enters the Buck step-down pre-regulator stage. The Buck stage includes a power switch, a freewheeling device, an energy storage inductor, an output filter capacitor, and a drive circuit. The control unit outputs a high-frequency PWM to control the duty cycle of the Buck stage. The Buck output is connected to a linear fine-tuning stage, which can be constructed using a power MOSFET, a sampling resistor, an operational amplifier, or an equivalent analog control circuit. The control unit provides a reference control value to the linear fine-tuning stage via a DAC. The output of the linear fine-tuning stage is then connected to an H-bridge, and the two outputs of the H-bridge are connected to welding electrodes or micro-wire clamps.

[0043] After power-on, the control unit sequentially initializes the H-bridge control terminal, Buck PWM, DAC, ADC, DMA, touchscreen, and recipe storage module. During initialization, the H-bridge remains off, the DAC output is set to zero, and the Buck duty cycle is set to zero to prevent erroneous outputs upon power-on. In standby mode, the control unit continuously keeps the linear stage and H-bridge off. When the operator clicks the welding start button, the control unit clears the historical waveform buffer, resets the waveform phase, resets the PID state, reads the current recipe, and enters the high-speed control loop.

[0044] In the high-speed control loop, the control unit first reads the current sample value, the welding output voltage sample value, and the Buck output voltage sample value. To reduce the impact of ADC noise on the microwire welding current feedback, first-order smoothing can be performed on the current sampling; for example, the output value is equal to 0.25 times the new sample value plus 0.75 times the previous output value. This processing does not change the structure of the controlled object; it only makes the feedback curve smoother and avoids single-point glitches directly causing abrupt changes in the DAC control quantity.

[0045] The outer loop of the Buck converter calculates the linear stage voltage drop margin based on the difference between the Buck output voltage and the welding output voltage, and compares it with the target margin. If the margin is too large, it indicates that the linear stage is experiencing too high a voltage drop, and the Buck duty cycle should be decreased; if the margin is too small, it indicates that the linear stage has insufficient adjustment margin, and the Buck duty cycle should be increased. The control unit uses incremental PID to calculate the Buck duty cycle and sets an upper limit on the duty cycle, for example, not exceeding 95%, to avoid inductor current runaway or insufficient drive margin under extreme duty cycles.

[0046] The linear fine-tuning inner loop calculates the DAC output based on the target amplitude given in the formula section and the current feedback value. For the constant current section, the feedback is the welding current; for the constant voltage section, the feedback is the welding voltage; for the constant power section, the power feedback can be calculated from the current and voltage; for the sinusoidal or sawtooth pulsation section, the control unit can generate the instantaneous target value by phase accumulation and output it to the linear stage to form the corresponding waveform. The DAC output range is limited to a safe range, for example, a 12-bit DAC corresponds to 0 to 4095. In engineering implementation, the maximum amplitude can be further limited to prevent chipping.

[0047] When polarity variation is disabled, the H-bridge remains forward-biased, and the linear fine-tuning stage outputs welding current according to the recipe. When polarity variation is enabled, the control unit calculates the commutation cycle based on the set frequency. For example, with a control loop frequency of 50kHz and a polarity variation frequency of 200Hz, one commutation cycle corresponds to 250 control cycles. The control unit drives the H-bridge forward in the first half of the cycle and reverses it in the second half. Several control cycles are reserved as a dead zone before each commutation. During the dead zone, the DAC output is set to zero and the H-bridge is turned off, allowing the current to decay before commutation.

[0048] Specific Implementation Example 2: Multi-segment programmable welding recipe and waveform generation.

[0049] In this embodiment, the welding recipe consists of up to ten welding segments, each including waveform type, amplitude, duration, and frequency. Waveform types may include off, constant current, constant voltage, constant power, sinusoidal pulsation, and sawtooth pulsation. The operator can select the waveform type of a segment via a touchscreen and set the amplitude, time, and frequency accordingly. For DC welding segments, the frequency parameter may not be involved in control; for sinusoidal and sawtooth welding segments, the frequency is used to generate periodic waveforms.

[0050] After welding begins, the control unit sequentially matches the current segment according to the total welding time. While the current segment is still in progress, the control unit continues to use the segment parameters to generate the target value; when the current segment is completed, it automatically enters the next valid segment; when all valid segments are completed, welding automatically stops and the Buck, linear output, and H-bridge are shut down. This method allows for the formation of a combined process of "low-amplitude preheating segment, high-amplitude main welding segment, pulse shaping segment, and slow-descent holding segment," as well as a cyclic welding process involving variable polarity.

[0051] In the sinusoidal pulsation segment, the control unit can employ a fixed-point sine lookup table and a phase accumulator. Each control loop calculates the phase step based on the frequency, retrieves a value from the sine table, and multiplies its absolute value by the segment amplitude to obtain the instantaneous target. Using the absolute value ensures the amplitude target remains non-negative, and the H-bridge determines the current direction, preventing the DAC output from being incompatible with the unipolar analog control port. In the sawtooth pulsation segment, the control unit forms a linearly rising target based on the high-order bits of the phase accumulator, returning to the starting point after reaching the end of the cycle. This scheme has low computational complexity and is suitable for resource-constrained microcontrollers operating within a 50kHz control loop.

[0052] The recipe data is stored in non-volatile memory, including waveform parameters for each segment, polarity change enable status, and polarity change frequency. Upon system startup, the system reads the magic word to determine if a valid recipe already exists; if one exists, it is loaded directly; otherwise, a default recipe is written. This design prevents parameter loss after power failure and facilitates rapid reproduction of different wire processing techniques.

[0053] Specific Implementation Example 3: Synchronous Sampling, Protection, and Process Display.

[0054] In this embodiment, the control unit uses an advanced timer as a high-speed time base. This timer outputs Buck PWM on one hand and generates a trigger signal on the other, causing the ADC to sample current, voltage, and Buck output voltage at a predetermined phase. The ADC is configured in scan multi-channel mode, and the DMA is configured in cyclic mode, transferring the results of each conversion to a fixed buffer. The DMA transfer completion interrupt does not execute the full control algorithm every time, but executes the welding control loop according to a predetermined frequency division, for example, executing a 50kHz closed-loop control every four 200kHz samples, thereby balancing sampling synchronization and CPU load.

[0055] Current and voltage data during the welding process are written to a historical cache at a certain extraction ratio. The touchscreen interface can display real-time recipes, polarity switch, polarity frequency, Q-Stop switch, temperature information, and welding history curves. The historical curves can be switched between display modes for current, voltage, power, and equivalent resistance. Power can be estimated from current and voltage, and equivalent resistance can be estimated from the voltage-to-current ratio. This display serves only as an operation and debugging interface and does not change the main power supply control structure.

[0056] The protection logic includes standby safety lockout, overcurrent / overvoltage hard limit, temperature protection, dynamic resistance trend protection, and automatic shutdown upon completion of soldering. In standby mode, the DAC, H-bridge, and Buck are all set to zero or turned off. If a serious abnormality is detected during soldering, the soldering stop flag is immediately activated, the H-bridge is turned off, the DAC output is cleared, and the Buck duty cycle is turned off. In dynamic resistance protection, when the current exceeds the effective threshold, the control unit calculates R=U / I and performs first-order smoothing, continuously recording the peak value Rpeak. When the smoothing resistance falls below a preset percentage of Rpeak, such as 80%, and this is confirmed more than a preset number of times, the solder joint is considered to have entered a weld nugget collapse or overmelting risk zone. If protection is enabled, the output is stopped.

[0057] Finally, the embodiments of the present invention will be explained and described in conjunction with the accompanying drawings: like Figure 1 The diagram shown is a block diagram of the overall structure of the composite microwire welding power supply of the present invention, illustrating the connection relationships between the DC input, the Buck step-down pre-regulator stage, the linear fine-tuning stage, the variable polarity H-bridge output stage, the welding electrode, the current / voltage / Buck voltage sampling, the embedded control unit, the touch screen, and the recipe storage.

[0058] like Figure 3 The diagram shown is a topology diagram of the Buck pre-regulator linear fine-tuning and H-bridge main circuit, illustrating the Buck power switch, inductor, capacitor, linear regulator, H-bridge output stage, sampling resistor, and various feedback detection points.

[0059] like Figure 4 The diagram shown is a flowchart of synchronous sampling and closed-loop control, illustrating the execution sequence of TIM8 triggering ADC, DMA transfer, 50kHz control loop, current filtering, recipe target generation, Buck outer loop, linear stage control, H-bridge commutation, and protection recording.

[0060] like Figure 5 The diagram shown is a timing diagram of low-current commutation of a variable polarity H-bridge, illustrating forward conduction, DAC being set to zero before commutation, H-bridge turn-off dead time, reverse conduction, and the next commutation dead time.

[0061] like Figure 6 The diagram shown is a flowchart of the execution of a multi-segment programmable welding recipe, illustrating the processes of recipe loading, current segment positioning, waveform target generation, output control, segment end judgment, and all segment end shutdown.

[0062] like Figure 7 The diagram shown is a flowchart of Q-Stop dynamic resistor-assisted soldering stop protection, illustrating current and voltage sampling, R=U / I calculation, filtering, peak tracking, continuous drop confirmation, and soldering stop output.

[0063] like Figure 8 The image shown is an auxiliary diagram of the system's operating interface. Figure 8 The system's operating interface displays recipe settings, welding section parameters, waveform previews, equipment status, temperature telemetry, dynamic resistance, and peak resistance, and is used to illustrate the touchscreen's human-machine interaction and welding process monitoring functions.

[0064] Therefore, the embodiments of the present invention have the following distinguishing technical features compared to the prior art: 1) A micro-wire welding composite power supply structure is formed by connecting “Buck pre-regulator stage + linear fine-tuning stage + subsequent polarity-changing H-bridge output stage” in series. The Buck stage is used to reduce the voltage drop and heat dissipation of the linear stage, the linear stage is used to precisely adjust the welding output, and the H-bridge is used to switch the welding current in the forward and reverse directions.

[0065] 2) A control method that adjusts the Buck duty cycle based on the difference between the Buck output voltage and the welding output voltage to maintain the target voltage drop margin of the linear fine-tuning stage.

[0066] 3) A synchronous control structure that coordinates Buck PWM, ADC triggering, DMA transfer, and closed-loop control calculations using the same high-speed timing reference.

[0067] 4) A system structure that uses multi-channel synchronous sampling of welding current, welding voltage, and Buck output voltage, and uses them for linear fine-tuning inner loop, Buck pre-stabilization outer loop, historical waveform recording, and protection judgment, respectively.

[0068] 5) Before commutating the H-bridge, reduce the linear fine-tuning stage control quantity to zero or a safe low value, and shut down the H-bridge to form a dead zone, then switch to a low-current commutation method with forward and reverse conduction states.

[0069] 6) A method for linking multi-segment programmable welding recipes with variable polarity parameters, wherein the recipe segment includes at least waveform type, amplitude, duration and frequency, and the variable polarity parameters include at least enable state and switching frequency.

[0070] 7) A control method that generates the target waveform for microwire welding by looking up a sine table or accumulating phases, and whose direction is determined by the output of the linear fine-tuning stage and the H-bridge.

[0071] 8) Dynamic resistance peak tracking and continuous decline confirmation are used as auxiliary shutdown protection for composite microwire welding power supplies, rather than as a separate quality inspection device.

[0072] In summary, the embodiments of the present invention have the following advantages over the prior art: 1) Reduce heat generation in the linear fine-tuning stage. Because the Buck pre-regulator stage adjusts according to the voltage drop margin of the linear fine-tuning stage, the power consumption on the linear device is reduced from that under traditionally larger voltage drop conditions. Reduced to a controlled small pressure differential Under the same welding current, the average heat dissipation of the linear regulating transistor or MOSFET is significantly reduced, which helps to reduce the size of the heat sink, reduce the temperature rise, and improve the stability of continuous welding.

[0073] 2) Retains the fine control capability of linear output. The Buck stage handles coarse adjustment and efficiency improvement, while the linear stage handles the final fine adjustment of the micro-welding current, avoiding direct input of simple switching power supply ripple to the solder joint. For micro-wires with small heat capacity and narrow welding window, this solution can achieve programmable outputs such as multi-segment amplitude, sine or sawtooth pulsation under low ripple conditions.

[0074] 3) Improves localized overmelting caused by unidirectional welding. The subsequent H-bridge allows the welding current to alternate in both directions at a set frequency, reducing electrode bias, heat bias, and the tendency for localized overmelting under long-term single-polarity operation. Compared to ordinary fixed DC output, this structure is suitable for more balanced control of heat distribution on both sides of the microwire solder joint.

[0075] 4) Reduce commutation shock. By reducing the DAC output and shutting down the H-bridge before commutation, a low-current commutation dead zone is created before switching between forward and reverse directions, reducing the risk of bridge arm shoot-through, current spikes, and instantaneous impacts on solder joints. This effect directly corresponds to the two structural features of "the linear stage can be quickly reduced to low output" and "the H-bridge has a post-polarity change".

[0076] 5) Improve closed-loop data consistency. Buck PWM, ADC triggering, DMA transfer and control algorithms are coordinated by a unified time base. Welding current, voltage and Buck output voltage are sampled under a defined phase relationship, reducing phase drift of software polling sampling, which helps to improve closed-loop stability and waveform recording reliability.

[0077] 6) Enhanced welding process adaptability. Multi-stage recipes can cover process steps such as preheating, main welding, slow descent, pulsation, and variable polarity output. With non-volatile memory and a touch screen human-machine interface, process parameters can be quickly recalled for different wire diameters, materials, and terminal structures.

[0078] 7) Provides auxiliary quality protection. The peak value and downward trend of dynamic resistance are used to judge the risk of weld nugget growth and over-melting. When abnormal trends are found, welding can be stopped or an alarm can be triggered in advance to reduce the risk of overheating, spattering or cold solder joints.

[0079] The preferred embodiments of the present application have been described above with reference to the accompanying drawings, but this is not intended to limit the scope of the embodiments of the present application. Any modifications, equivalent substitutions, and improvements made by those skilled in the art without departing from the scope and substance of the embodiments of the present application shall be within the scope of the embodiments of the present application.

Claims

1. A Buck pre-regulated linear variable polarity microwire welding power supply, characterized in that, It includes a DC input terminal, a pre-regulation module, a linear adjustment module, a variable polarity output module, a detection module, and a control module, wherein: The DC input terminal is connected to the pre-regulator module and is used to provide DC input power to the pre-regulator module; The pre-regulator module is connected to the linear regulator module and is used to step down and regulate the DC input power to generate a pre-regulated voltage. The pre-regulated voltage is adjusted according to the first control signal output by the control module so that the linear regulator module is within a preset voltage drop range. The linear adjustment module is connected between the pre-stabilized voltage module and the variable polarity output module, and is used to finely adjust the pre-regulated voltage according to the second control signal output by the control module to generate the target welding output voltage or the target welding output current. The variable polarity output module is connected to the linear adjustment module and is used to change the welding output polarity according to the direction control signal output by the control module to form a positive welding output or a reverse welding output. The detection module is connected to the variable polarity output module, the pre-stabilized voltage module and the control module respectively, and is used to collect welding output current data, welding output voltage data and pre-stabilized voltage data; The control module is used to generate the first control signal, the second control signal, and the direction control signal based on the welding output current data, the welding output voltage data, and the pre-stabilized output voltage data, so as to control the pre-stabilized module, the linear adjustment module, and the variable polarity output module to work together to realize constant current control, constant voltage control, constant power control, and variable polarity control in the microwire welding process.

2. The Buck pre-regulated linear variable polarity microwire welding power supply according to claim 1, characterized in that, The pre-regulator module includes a Buck step-down circuit, switching devices, and a PWM drive circuit, wherein: The PWM drive circuit is connected to the control module and is used to generate a PWM drive signal according to the first control signal and send it to the switching device to adjust the output voltage of the Buck step-down circuit.

3. The Buck pre-regulated linear variable polarity microwire welding power supply according to claim 2, characterized in that, The control module calculates the voltage drop margin of the linear adjustment module based on the voltage difference between the pre-regulated output voltage data and the welding output voltage data, and generates the first control signal based on the voltage drop margin to make the linear adjustment module work in a preset low voltage drop state.

4. The Buck pre-regulated linear variable polarity microwire welding power supply according to claim 3, characterized in that, The detection module includes a welding current sampling unit, a welding voltage sampling unit, and a pre-regulated voltage sampling unit, wherein: The welding current sampling unit is used to acquire welding current feedback data; The welding voltage sampling unit is used to acquire welding voltage feedback data; The pre-regulated voltage sampling unit is used to acquire the pre-regulated voltage feedback data.

5. The Buck pre-regulated linear variable polarity microwire welding power supply according to claim 4, characterized in that, The control module includes a waveform generation unit, a closed-loop adjustment unit, and a protection unit, wherein: The waveform generation unit is used to generate constant current waveforms, constant voltage waveforms, constant power waveforms, sinusoidal pulsating waveforms, or sawtooth pulsating waveforms according to preset welding parameters. The closed-loop adjustment unit is used to adjust the output of the linear adjustment module based on the data fed back by the detection module. The protection unit is used to perform protection control based on abnormal current data, abnormal voltage data, or abnormal power data collected by the detection module.

6. A method for using a Buck pre-regulated linear variable polarity microwire welding power supply, characterized in that, Includes the following steps: Acquire welding output current data, welding output voltage data, and pre-regulated output voltage data; The voltage drop margin of the current linear adjustment module is calculated based on the pre-regulated output voltage data and the welding output voltage data. First adjustment data is generated based on the difference between the voltage drop margin and the preset voltage drop target value, and a PWM control signal is generated based on the first adjustment data; The output voltage of the pre-regulator module is adjusted according to the PWM control signal so that the voltage drop margin of the linear adjustment module is within a preset range. Target output data is generated based on welding process parameters, and second control data is generated based on the deviation between the target output data and the welding output current data or the welding output voltage data. Adjust the output of the linear adjustment module according to the second control data so that the welding output meets the target welding parameters.

7. The method of using the Buck pre-regulated linear variable polarity microwire welding power supply according to claim 6, characterized in that, The step of generating target output data based on welding process parameters specifically includes: Read the preset welding recipe data; The output mode, output amplitude, duration, and frequency parameters corresponding to the current welding stage are determined based on the welding recipe data. Based on the output mode, generate corresponding target current data, target voltage data, or target power data.

8. The method of using the Buck pre-regulated linear variable polarity microwire welding power supply according to claim 6, characterized in that, Also includes: The current welding stage is determined based on the welding formula data and cumulative welding time. Acquire the target waveform data corresponding to the current welding stage, and generate target output data based on the target waveform data; The target output data is compared with the acquired welding output current data or welding output voltage data to obtain the output deviation data; The second control data is updated based on the output deviation data, and the updated second control data is sent to the linear adjustment module so that the linear adjustment module outputs a welding waveform corresponding to the current welding stage.

9. The method of using the Buck pre-regulated linear variable polarity microwire welding power supply according to claim 6, characterized in that, Also includes: Calculate the dynamic resistance data based on the welding output voltage data and the welding output current data; The dynamic resistance data is filtered to obtain dynamic resistance change data; The dynamic resistance change data is compared with a preset dynamic resistance threshold to obtain the welding status judgment result; Adjust the target output data or the second control data according to the welding status judgment result; The linear adjustment module outputs welding current based on the adjusted second control data to achieve weld nugget formation judgment and abnormal state protection during the welding process.

10. The method of using the Buck pre-regulated linear variable polarity microwire welding power supply according to claim 6, characterized in that, Also includes: Generate commutation control data based on the polarity control parameters in the target output data; The polarity switching time is determined based on the commutation control data, and the commutation condition is determined based on the current welding output current data. When the commutation condition is met, a polarity switching control signal is generated, causing the variable polarity output module to switch the output direction. After completing the polarity switch, the second control data is regenerated based on the target output data, and the linear adjustment module is controlled to restore the target welding output.

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