Lithium electric welding machine integrated with power factor correction and active rectification structure

Abstract

The invention relates to the technical field of welding equipment manufacturing, and provides a lithium electric welding machine integrated with a power factor correction and active rectification structure. The welding machine comprises a main control chip, a lithium battery power supply module, a welding power control module, a charging management module, a voltage safety control module, a multi-stage isolation sampling module, an asymmetric half-bridge power supply module and a man-machine interaction module. The welding power control module adopts double MOS tube complementary driving to realize active rectification, and the chopping unit adjusts welding current through pulse width modulation. The charging management module is integrated with a power factor correction unit and works in linkage with the welding power control module, and the bus voltage stability is optimized. The voltage safety control module dynamically switches welding machine terminal voltage to a safety threshold value, the multi-stage isolation sampling module achieves battery voltage isolation sampling, and the man-machine interaction module provides a parameter digital setting and displaying function.

Description

Technical Field

[0001] The invention relates to the technical field of welding equipment manufacturing, and in particular to a lithium-ion welding machine with integrated power factor correction and active rectification structures. Background Art

[0002] Traditional lithium-ion battery welding machines suffer from deficiencies in energy conversion efficiency and welding current control accuracy. This is particularly true for complex welding processes, where it's difficult to balance power factor correction with stable welding current regulation. Existing technologies often implement power factor correction and welding current control in separate functional modules, increasing system complexity and cost while also hindering overall performance optimization. Therefore, developing a lithium-ion battery welding machine with integrated power factor correction and active rectification is a key requirement for improving welding equipment performance. Summary of the Invention

[0003] In view of the above-mentioned technical deficiencies, the purpose of the present invention is to provide a lithium battery welding machine with integrated power factor correction and active rectification structure to solve the problems of low energy conversion efficiency and inaccurate welding control in the prior art.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions: In a first aspect, the present invention provides a lithium-ion welding machine with integrated power factor correction and active rectification structure, comprising: Main control chip; Lithium battery power module; The welding power control module includes an active rectifier unit and a chopper unit. The active rectifier unit uses a dual-MOS tube complementary drive structure to achieve rectification in the continuous conduction mode, and the chopper unit adjusts the welding current through pulse width modulation technology. The charging management module integrates a power factor correction unit consisting of an IGBT tube, a fast recovery diode, and a BOOST inductor, and combines a half-bridge inverter topology with a high-frequency transformer to achieve charging voltage conversion; The voltage safety control module, consisting of a voltage divider network, a voltage comparator, and a trigger diode, dynamically switches the voltage at the welding machine terminal to a safety threshold; Multi-stage isolation sampling module, using isolation amplifier and differential circuit to achieve battery voltage isolation sampling; Asymmetric half-bridge power module generates multi-channel isolated power supply by integrating N+P type MOS tube driver chip; Human-computer interaction module, equipped with rotary encoder and segment code screen to realize digital setting and display of parameters; Among them, the charging management module is connected to the lithium battery power supply module, the welding power control module is driven by the main control chip signal, the voltage safety control module output signal is connected to the main control chip interrupt interface, the multi-level isolation sampling module is connected to the main control chip AD interface, the asymmetric half-bridge power supply module provides power for the IGBT drive, and the human-computer interaction module interacts with the main control chip through the communication interface.

[0005] Preferably, in a possible implementation manner of the first aspect, the gates of the dual MOS tubes in the welding power control module receive complementary PWM signals output by the main control chip and set dead time control logic; In the continuous conduction mode of the inductor current of the chopper unit, when the first MOS tube is turned on, the second MOS tube is turned off to realize the forward current path. When the second MOS tube is turned on, the first MOS tube is turned off to form a reverse freewheeling path. During the dead time, the body diode of the second MOS tube maintains the continuity of the inductor current. The chopper unit realizes the pulse width modulation output of the welding current by adjusting the duty cycle of the complementary PWM signal. The main control chip dynamically adjusts the dead time parameters according to the load current feedback to match the requirements of different welding processes.

[0006] Preferably, in a possible implementation manner of the first aspect, in the dual MOS transistor complementary drive structure of the active rectifier unit, a pulse generator with a phase difference of 180° is built into the main control chip to generate two reference square wave signals, and the two drive signals are respectively connected to the gates of the MOS transistors through independent gate drive circuits; The second MOS tube body diode assumes the current freewheeling function during the dead time stage, and the main control chip is configured with an adaptive dead time compensation algorithm to optimize the dead time parameters in real time by detecting the phase offset of the inductor current zero crossing point.

[0007] Preferably, in a possible implementation manner of the first aspect, the independent gate drive circuit includes a current limiting resistor connected in series to the gate of the MOS transistor and an RC buffer network connected in parallel between the gate and source; The current limiting resistor value is set according to the MOS tube input capacitance and the output current capability of the driver chip, and the RC buffer network time constant is set to 1 / 15 of the complementary PWM signal period to suppress high-frequency oscillation. The adaptive dead-time compensation algorithm samples the peak-to-peak value of the inductor current ripple and combines it with the MOS tube junction temperature sensor data to construct a three-dimensional compensation curve, dynamically correcting the dead-time parameters to balance switching losses and current continuity requirements.

[0008] Preferably, in a possible implementation manner of the first aspect, when the power factor correction unit and the active rectifier unit of the charging management module enter a linkage working mode, the main control chip synchronously controls the switching timing of the IGBT tube of the power factor correction unit and the MOS tube of the welding power control module, so that the inductive energy storage cycle of the BOOST boost circuit and the current freewheeling stage of the active rectifier unit operate in phase shift; In the half-bridge inverter topology, the primary winding of the high-frequency transformer is connected in parallel with the output capacitor of the power factor correction unit, and the secondary winding is connected to the lithium battery charging port after center-tapped full-wave rectification. The main control chip adjusts the half-bridge inverter frequency according to the battery voltage sampling value to achieve constant current-constant voltage charging mode switching.

[0009] Preferably, in a possible implementation of the first aspect, in the linkage working mode, the main control chip controls the conduction duty cycle of the power factor correction unit IGBT tube and the welding power module MOS tube through a time-sharing multiplexing drive signal bus, and when a sudden increase in welding current demand is detected, the charging power is preferentially reduced to maintain bus voltage stability.

[0010] Preferably, in a possible implementation manner of the first aspect, the voltage safety control module includes a voltage divider resistor network connected in series between the welding machine terminal and ground, the voltage divider node is connected to the non-inverting input terminal of the voltage comparator, and the inverting input terminal is connected to the safety threshold voltage generated by the reference voltage source; When the welding terminal is open, the voltage at the voltage divider node exceeds the safety threshold voltage, triggering the comparator to flip. The output signal is transmitted to the main control chip after optical isolation to trigger the low voltage protection mode. At this time, the welding terminal voltage is clamped below the welding terminal safety voltage threshold. When welding current is detected, the main control chip automatically releases the voltage clamp and activates full power output.

[0011] Preferably, in a possible implementation manner of the first aspect, the multi-stage isolation sampling module adopts an isolation amplifier architecture based on capacitive coupling, the high-voltage side includes a voltage divider network and a differential input filter, and the low-voltage side includes a programmable gain instrumentation amplifier; The voltage divider network uses multiple stages of thick-film resistors connected in series and temperature compensation capacitors in parallel. The differential input filter consists of a common-mode choke and a π-type RC network. The output of the isolation amplifier is connected to the AD conversion channel of the main control chip after second-order active low-pass filtering. The main control chip has a built-in nonlinear correction algorithm to eliminate measurement errors caused by temperature drift of the voltage divider network.

[0012] Preferably, in a possible implementation manner of the first aspect, the high-voltage arm of the voltage divider network adopts a structure of multiple equal-value resistors connected in series, and each series node is connected in parallel with a high-frequency ceramic capacitor to form a distributed filtering network; The temperature compensation capacitor is a negative temperature coefficient film capacitor, the slope of its capacitance change matches the positive temperature coefficient of the voltage divider resistor, and together they form a temperature self-balancing voltage divider system; The nonlinear correction algorithm performs dynamic compensation by establishing a quartic polynomial model of the voltage divider ratio varying with temperature and combining it with real-time temperature sampling data.

[0013] Preferably, in a possible implementation manner of the first aspect, the asymmetric half-bridge power supply module uses an N+P-type MOS transistor integrated chip as a power switching device, and its gate drive signal is generated by a dedicated driver chip to generate a complementary square wave with opposite phases. When the drive signal is high, the N-type MOS is turned on to form a forward energy transmission path, and when the drive signal is low, the P-type MOS is turned on to form a reverse energy recovery path. The secondary side of the transformer of the multi-channel isolated power supply adopts a dual-winding full-wave rectifier structure, each rectifier branch is connected in series with a magnetic bead filter and in parallel with a transient voltage suppression diode, and a balancing resistor network is connected across the positive and negative output terminals to maintain voltage symmetry.

[0014] The beneficial effects of the present invention are as follows: by integrating power factor correction and active rectification structure, the present invention significantly improves the energy conversion efficiency of lithium-ion welding machines, reduces reactive power loss, and simultaneously realizes precise pulse width modulation output of welding current, meeting the requirements of different welding processes. The linkage working mode of the charging management module and the welding power control module further optimizes the stability of the bus voltage and ensures the reliability of welding quality. In addition, the design of the multi-stage isolation sampling module and the voltage safety control module enhances the safety and measurement accuracy of the system, and the configuration of the human-computer interaction module improves the convenience of operation. Overall, the present invention effectively solves the technical bottlenecks of traditional lithium-ion welding machines in energy conversion efficiency and welding current control, and promotes the progress of welding equipment manufacturing technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 A structural diagram of a lithium-ion welding machine with integrated power factor correction and active rectification structure is provided for this application. DETAILED DESCRIPTION

[0017] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0018] Example 1: Figure 1 As shown, the present invention provides a lithium-ion welding machine with integrated power factor correction and active rectification structure, including a main control chip, a lithium battery power supply module, a welding power control module, a charging management module, a voltage safety control module, a multi-stage isolation sampling module, an asymmetric half-bridge power supply module and a human-computer interaction module.

[0019] The charging management module is connected to the lithium battery power supply module, the welding power control module is driven by the main control chip signal, the voltage safety control module output signal is connected to the main control chip interrupt interface, the multi-level isolation sampling module is connected to the main control chip AD interface, the asymmetric half-bridge power supply module provides power for the IGBT driver, and the human-computer interaction module interacts with the main control chip through the communication interface.

[0020] In this embodiment, the main control chip utilizes an STM32F407 microcontroller, which connects to the welding power control module via a CAN bus interface. It features two complementary PWM output channels, each driving the dual MOSFETs in the active rectifier unit. The chip incorporates an adaptive dead-time controller that adjusts the phase difference of the MOSFET drive signals in real time based on the inductor current sampling signal. An integrated temperature sensor interface collects power device junction temperature data, constructing a three-dimensional compensation curve to optimize switching timing. The main control chip's ADC module, connected to the output of the multi-stage isolation sampling module, utilizes oversampling technology to process the battery voltage signal. A quartic polynomial temperature compensation algorithm stored in Flash memory eliminates temperature drift errors in the voltage divider network. The interrupt controller directly receives the comparator signal output by the voltage safety control module. Upon detecting an open-circuit at the welding terminal, it immediately triggers a protection mechanism, controlling the power module to enter low-voltage output mode via the GPIO port. Furthermore, the main control chip communicates with the encoder and segment display of the human-machine interface module via the I2C communication protocol, enabling digital setting of welding parameters and real-time status display.

[0021] The lithium-ion battery power module utilizes multiple lithium iron phosphate cells connected in series to form a 48V battery pack. It features an intelligent battery management system (BMS) for charge and discharge protection and status monitoring. A bidirectional thermistor and multi-stage fuse protection device are connected in series to the positive output terminal of the battery pack, which is then connected to the DC bus of the welding power control module via a low-impedance copper busbar. The BMS integrates a voltage balancing circuit and employs an active energy transfer topology to achieve dynamic charge balancing between individual cells. A temperature sensor array is installed at the bottom of the battery pack to collect real-time cell surface temperature data. When a cell temperature exceeds 60°C, a graded power reduction protection is triggered. A transient voltage suppression (TVS) module, consisting of a TVS diode array and an RC snubber network, is connected in parallel to the battery pack output to absorb voltage spikes generated in the welding circuit. The BMS communicates with the main control chip via the CAN bus, transmitting battery state of charge, health status, and fault code information. The main control chip dynamically adjusts the maximum output power threshold based on the remaining battery capacity, automatically reducing the upper welding current limit in low-battery mode to extend battery life.

[0022] The welding power control module includes an active rectifier unit and a chopper unit. The active rectifier unit adopts a dual MOS tube complementary drive structure to achieve rectification in the current continuous conduction mode, and the chopper unit adjusts the welding current through pulse width modulation technology.

[0023] Specifically, the welding power control module, the core power processing unit of the lithium-ion battery welding machine, uses a dual-MOSFET complementary drive structure and an adaptive control strategy to achieve efficient active rectification and current modulation. The module consists of an active rectification unit and a chopper unit, which, through the coordinated control of the main control chip, form a complete welding power processing chain.

[0024] The active rectifier unit uses IRFS7530 N-channel MOS transistors Q1 and Q2 to create a complementary drive structure. The sources of the two MOS transistors are connected to the positive pole of the 48V DC bus, and the drains are connected to the two ends of the chopper unit inductor, forming a bidirectional current path. The main control chip STM32F407 generates two reference square wave signals with a phase difference of 180 degrees through its timer TIM1. After processing by the dead time controller, a complementary PWM drive signal is formed. The drive signal is processed by an independent gate drive circuit: each signal is first amplified by the UCC27517 driver chip, and then connected in series. The current limiting resistor and the parallel RC snubber network (composed of a 100Ω resistor and a 470pF capacitor) perform waveform shaping and are ultimately applied to the MOS transistor gate. The current limiting resistor value is calculated and set based on the MOS transistor input capacitance (typical value 3800pF) and the driver chip peak output current (4A), ensuring that the gate charging time constant is controlled within 50ns. The time constant of the RC snubber network is set to the complementary PWM signal period (20kHz corresponds to 1 / 15 of the period) , effectively suppressing high-frequency oscillations during the switching process.

[0025] In terms of working timing control, when the PWM1 signal output by the main control chip is high, Q1 is fully turned on through the drive circuit. At this time, the PWM2 signal is at a low level, causing Q2 to be turned off. The current forms a forward path from the DC bus through Q1, inductor L3, and welding load. When the PWM2 signal jumps to a high level, Q2 is turned on and Q1 is turned off. The energy stored in the inductor of the chopper unit forms a reverse freewheeling path through Q2. There is a circuit between the two drive signals. The basic dead time is the period during which both Q1 and Q2 are in the off state. At this time, the continuity of the inductor current is maintained by the internal body diode of Q2. The adaptive dead time compensation algorithm built into the main control chip collects the peak-to-peak value of the inductor current ripple in real time through the Hall sensor. Combined with the data of the PT1000 temperature sensor installed on the MOS tube heat dissipation substrate, it constructs a three-dimensional compensation curve with current slope, junction temperature and dead time as variables. When a phase offset is detected at the zero crossing point of the inductor current, the algorithm dynamically adjusts the dead time parameters, and the compensation range is controlled within , achieving the optimal balance between switching loss and current continuity.

[0026] The chopper unit uses a customized power inductor (inductance , saturation current 120A) as an energy storage element, its output end is connected to the welding gun terminal through a low impedance copper busbar. The main control chip sets the target current value according to the welding process parameters, and adjusts the duty cycle of the complementary PWM signal (adjustment range ) achieves pulse-width modulation of the welding current. When the rotary encoder sets the current to increase, the main control chip gradually increases the PWM duty cycle within a 10ms period, while simultaneously monitoring bus voltage fluctuations and maintaining output voltage stability through a feedforward control algorithm. During dynamic operation, the current feedback loop samples the load current signal in real time at a 20kHz sampling rate. After passing through a second-order Butterworth low-pass filter, the signal is input to the main control chip's ADC module, forming a closed-loop control system. In particular, when a sudden current change is detected at the moment of welding arc initiation, the system automatically enters constant voltage control mode to prevent current overshoot caused by a sudden drop in load impedance.

[0027] In terms of thermal management, the dual MOS tubes are installed on a forced air cooling radiator, and the heat dissipation substrate integrates a temperature sensor array. The main control chip reads the junction temperature data in real time through the I2C interface. When it detects that the junction temperature of any MOS tube exceeds 110°C, the derating protection is immediately triggered: first, the PWM duty cycle upper limit is dynamically lowered to 80% of the current value. If the temperature continues to rise, the output power is gradually reduced by 10% until the temperature drops back to the safe threshold. This protection mechanism works in conjunction with the adaptive dead zone compensation algorithm to automatically extend the dead zone time under high temperature conditions. To reduce switching losses while ensuring the stability of the inductor current in continuous conduction mode.

[0028] The charging management module integrates a power factor correction unit consisting of an IGBT tube, a fast recovery diode and a BOOST inductor, and combines a half-bridge inverter topology and a high-frequency transformer to achieve charging voltage conversion.

[0029] Specifically, the charging management module consists of an IGBT tube (model: IRG4PH50UD), a fast recovery diode (model: FFH30UP60S), a BOOST inductor (inductance ) and filter capacitors ( The power factor correction unit (PFC) is composed of a 450V / 450V electrolytic capacitor. A half-bridge inverter topology employs IGBTs (model: IRG4PC50W) and a high-frequency transformer (20:1 ratio, 2mH primary winding inductance) to form the charging voltage conversion link. The secondary winding undergoes center-tapped full-wave rectification before being connected to the lithium battery charging port. The main control chip uses a time-sharing drive bus to achieve coordinated control of the PFC unit and the welding power control module, ensuring dynamic optimization of system energy distribution.

[0030] In the power factor correction unit, the gate drive signal for the IGBT is generated by the TIM8 channel of the STM32F407 main control chip, with a switching frequency set to 65kHz. When the IGBT is on, the pulsating DC current from the mains, output via rectifier bridge D1, flows through the boost inductor to store energy. When the IGBT is off, the boost inductor releases energy through the fast recovery diode to charge the filter capacitor, generating a boosted output voltage. The main control chip uses a Hall effect current sensor to collect the mains input current waveform in real time. Using an average current control algorithm, the PWM duty cycle is dynamically adjusted to synchronize the input current phase with the voltage, improving the power factor to above 0.98. In particular, the boost inductor uses a nanocrystalline core material with a saturation flux density of 1.2T, effectively suppressing core losses under high-frequency operating conditions.

[0031] When the system enters linked operation mode, the main control chip uses a hardware synchronization signal interface to coordinate the timing of the IGBTs in the power factor correction unit and the MOSFETs in the welding power module. Specifically, the boost circuit's inductive energy storage cycle is configured within the dead time interval of the active rectifier unit's MOSFETs. A phase-locked loop (PLL) is used to ensure that the switching operations of the two circuits are 180° out of phase. This timing alignment strategy effectively reduces bus voltage ripple. The primary winding of the high-frequency transformer is directly connected in parallel across the output capacitor of the power factor correction unit. The secondary winding is connected to a full-wave rectifier circuit via a Schottky diode (model: MBR20200CT). The output is connected to the lithium battery charging port via a series filter inductor. The main control chip acquires battery voltage data through a multi-stage isolated sampling module. When the battery voltage is detected to be below 54V, the half-bridge inverter circuit is controlled to operate at a 120kHz frequency for constant-current charging. When the voltage reaches 54V, it automatically switches to an 80kHz frequency for constant-voltage charging.

[0032] Dynamic power distribution in linkage mode is achieved by time-division multiplexing the drive signal bus. The TIM1 / TIM8 timer channel of the main control chip uses time-division multiplexing technology to integrate the drive signals of the IGBT tube and MOS tube into the same physical bus. The bus transmission layer protocol sets the priority mechanism: when the current feedback circuit detects that the welding current demand suddenly increases by more than 115% of the set threshold, the interrupt service routine is immediately triggered, and the main control chip The PWM duty cycle of the power factor correction unit is stepped down from the base value of 75% to 50%, and the released power bandwidth is dynamically allocated to the welding power module. In this process, the bus voltage fluctuation is controlled within To cope with extreme working conditions, the module has a built-in over-temperature protection circuit. When the IGBT junction temperature sensor (model: KTY84-130) detects that the temperature exceeds 125°C, the charging current upper limit is automatically adjusted to The gradient decreases linearly and forms a linkage control with the thermal protection mechanism of the welding power module.

[0033] The charging management module's soft-start circuit consists of a current-limiting resistor and relay K1 (model HF115F). Initially, the relay is disconnected, allowing the AC power to pre-charge the filter capacitor via the current-limiting resistor, effectively suppressing inrush current. When the main control chip detects that the bus voltage reaches 300V, it activates the relay after a 150ms delay, entering normal operation. The module also integrates an RC snubber network connected in parallel across the IGBT to suppress voltage spikes during switching to less than 50V. The high-frequency transformer is wound with triple-insulated wire, features a 0.5mm Faraday shield between the primary and secondary sides, and has passed a 3.5kV withstand voltage test.

[0034] The voltage safety control module consists of a voltage divider network, a voltage comparator and a trigger diode, which dynamically switches the welding machine terminal voltage to a safety threshold.

[0035] Specifically, the voltage safety control module is composed of a precision voltage divider network, a high-speed voltage comparator and a photoelectric isolation trigger circuit to achieve dynamic safety control of the welding terminal voltage. The voltage divider network uses R1 ( )、R2( )、R3( )、R4( ) Four metal film resistors are connected in series and directly connected between the welding machine output terminal and the system ground terminal. The connection point between R3 and R4 is used as a voltage divider node. After filtering out high-frequency interference, the RC filter is connected to the non-inverting input of the voltage comparator LM393. The inverting input of the comparator is connected to a 3.3V precision reference voltage composed of a TL431 reference source. This reference circuit uses a constant current power supply mode and consists of a constant current diode and a filter capacitor to ensure that the temperature drift coefficient of the reference voltage is less than 50ppm / ℃. The comparator output is connected through The pull-up resistor is connected to the positive electrode of the light-emitting diode of the optocoupler PC817, the collector of the secondary transistor of the optocoupler is connected to the external interrupt pin of the main control chip, and the emitter is connected to the external interrupt pin of the main control chip. Pull-down resistor to ground.

[0036] Under normal working conditions, when the output terminal of the welding machine is in an open circuit condition, the 48V battery voltage is attenuated by the voltage divider network, and a 3.66V voltage divider value is generated at the voltage divider node. This voltage exceeds the 3.3V reference voltage of the inverting terminal of the comparator, triggering the comparator to output a high-level signal. The optocoupler PC817 is turned on and transmits the high-level signal to the main control chip. The main control chip STM32F407 immediately responds to the interrupt request, controls the PWM generator to enter the low-voltage output mode, and clamps the welding terminal voltage to below the 23.3V welding terminal safety voltage threshold by dynamically adjusting the duty cycle of the chopper unit. The response time of this protection mechanism is less than , which can effectively limit the contact voltage when the human body touches the welding clamp.

[0037] When the welder is welding, the output terminals form a conductive loop through the workpiece, and the voltage at the voltage divider node drops sharply to below 0.7V due to diode conduction. At this point, the voltage at the comparator's non-inverting terminal falls below the reference voltage at the inverting terminal, causing the output terminal to flip to a low level. The optocoupler turns off, sending a low-level signal to the main control chip. The main control chip releases the voltage clamp control and simultaneously activates the welding current detection algorithm: The Hall effect sensor monitors the load current in real time. When the current value remains greater than 5A for 200ms, the active welding state is confirmed, and full-power output mode is activated. To enhance anti-interference capabilities, the comparator circuit is equipped with a hysteresis loop, creating a hysteresis voltage of approximately 50mV to prevent false triggering due to contact vibration.

[0038] The multi-stage isolation sampling module uses an isolation amplifier and a differential circuit to achieve isolated battery voltage sampling.

[0039] Specifically, the multi-stage isolation sampling module uses an isolation amplifier architecture based on capacitive coupling to achieve high-precision isolated detection of battery voltage. It consists of a high-voltage side voltage divider network, a differential input filter, an isolation amplifier, and a low-voltage side signal conditioning circuit. The voltage divider network uses six equal-value thick film resistors (model MPR24) connected in series to form a high-voltage arm, and each resistor is connected in parallel. High-frequency ceramic capacitors (model GRM32) form a distributed filtering network. At the high-voltage arm's terminal node, a temperature compensation branch consisting of two negative temperature coefficient film capacitors (model FKT1G103Z) is connected in parallel. The slope of their capacitance changes complements the positive temperature coefficient of the voltage divider resistor, creating a temperature-controlled self-balancing voltage divider system. The low-voltage arm consists of a precision metal film resistor (model MRS25) connected in series with an adjustable potentiometer. Laser trimming achieves a voltage divider ratio error of less than 0.05%.

[0040] The differential input filter adopts a two-stage filtering structure. The front stage is equipped with a common mode choke (model DLW21) to suppress high frequency common mode interference, and the back stage is equipped with a common mode choke (model DLW21) to suppress high frequency common mode interference. Type RC network (resistance ) forms a low-pass filter with a cutoff frequency of 34kHz. The isolation amplifier uses the NSI1311 capacitor isolation chip, and its high-voltage input end is equipped with an electrostatic protection circuit consisting of a bidirectional TVS diode (model SMBJ15CA) and a series resistor (resistance value ) form a transient suppression network. The amplifier output is conditioned by a programmable gain instrumentation amplifier (AD8251), with an adjustable gain range of 1-100 times. The gain parameters are dynamically configured through the SPI interface of the main control chip to adapt to different range requirements. The conditioned signal passes through a second-order active low-pass filter to eliminate switching noise. The filter circuit is constructed using a zero-drift operational amplifier (OPA2188). The output signal is then filtered through a 16-bit The ADC (model ADS1115) converts the data into digital quantity and transmits it to the main control chip.

[0041] The nonlinear correction algorithm built into the main control chip implements temperature drift compensation through a quartic polynomial model. In specific implementation, a functional relationship is established between the voltage divider ratio and temperature: The coefficient ae is calibrated through high-temperature aging testing and stored in Flash memory. During real-time compensation, a temperature sensor (PT1000) collects the ambient temperature of the voltage divider network at a 10Hz sampling rate. The main control chip substitutes this temperature data into a polynomial model to calculate the current voltage divider ratio correction value and dynamically calibrates the ADC sampling value. The compensation algorithm incorporates an anomaly detection mechanism. When the temperature change rate exceeds 5°C / s, it automatically switches to backup linear compensation mode to prevent measurement deviations caused by sensor failure.

[0042] Asymmetric half-bridge power module generates multi-channel isolated power supply by integrating N+P type MOS tube driver chip.

[0043] Specifically, the asymmetric half-bridge power module uses an N+P MOSFET integrated circuit (model FDMF8810) as the power switching device. Its gate drive signal is generated by a dedicated driver chip, the UCC27714, which generates complementary square waves with opposite phases. The driver chip receives a 200kHz PWM signal from the main control chip and, after level conversion, outputs two complementary drive pulses with an amplitude of 12V. When the drive signal is high, the N-type MOSFET within the integrated chip conducts, forming a forward energy transfer path. The power bus voltage then flows through the N-type MOSFET, the energy storage capacitor bank, and the primary winding of the high-frequency transformer, forming a loop that transfers energy to the secondary winding. When the drive signal is low, the P-type MOSFET conducts, forming a reverse energy recovery path. The bus voltage, through the P-type MOSFET and the energy storage capacitor bank, reversely excites the high-frequency transformer, resetting the magnetic core. A 150ns dead time is set between the two drive signals to prevent shoot-through shorts through the driver chip's built-in interlock logic.

[0044] The high-frequency transformer utilizes an ER28 core and triple-insulated wire. The primary winding is bifilar-wound to reduce leakage inductance, while the secondary winding features two independent windings (1:1:1 turns ratio). Each secondary winding is connected to a full-wave rectifier branch, utilizing a fast-recovery diode (MBR2045CT) to create a dual-winding full-wave rectifier topology. A surface-mount bead filter (BLM18PG121SN1) is connected in series with the output of each rectifier branch to suppress high-frequency noise, and a bidirectional transient voltage suppressor diode (SMBJ15CA) is connected in parallel for overvoltage protection. The rectified positive and negative output terminals are each connected via a rectifier. The LC filter network is used for smoothing, and a balanced resistor network consisting of four metal film resistors is connected between the positive and negative output terminals to maintain the symmetry of the positive and negative voltages through equipotential distribution. During the operation of the power module, the main control chip dynamically adjusts the duty cycle of the drive signal by sampling the difference between the positive and negative output voltages. When the voltage deviation exceeds The automatic compensation mechanism is triggered when the power is off to ensure the long-term stability of the isolated power supply.

[0045] The human-computer interaction module is equipped with a rotary encoder and a segment code screen to realize digital setting and display of parameters.

[0046] Specifically, the human-machine interaction module uses a rotary encoder and a five-segment code screen to work together to achieve precise setting of welding parameters and multi-dimensional status display. The module's hardware consists of an EC11 incremental rotary encoder, a customized 8-bit segment code LCD screen, and the STM32F407's TIM4 encoder interface. The encoder signal line is connected to the main control chip's GPIO port via an RC debouncing filter circuit, and the segment code screen communicates with the main control chip via the SPI interface. The rotary encoder has a built-in 24-pulse / cycle mechanical structure, which, combined with the main control chip's 4x frequency decoding algorithm, achieves an angular resolution of 0.94°. During operation, clockwise rotation increases the parameter value, while counterclockwise rotation decreases it. A short press switches between welding current, thrust, and hot arc ignition parameter setting modes, and a long press for 3 seconds enters the system menu. The segmented display uses the HT1621B driver chip to control the display content, with six independent display areas: the upper left area displays the real-time welding voltage, the central circular icon dynamically displays the remaining battery charge, the upper right area digitally displays the preset welding current value, the lower left area uses a bar graph to indicate the welding thrust level, the lower middle area displays the arc ignition intensity as a percentage, and the lower right area reserves a two-digit fault code display window. The main control chip regularly refreshes the display buffer via the DMA channel. When an abnormal condition is detected, the fault code display priority is automatically activated, and the red LED warning light and buzzer alarm are triggered simultaneously. The module has built-in EMI shielding, and the encoder signal cable uses twisted pair transmission cable with a common-mode choke to ensure stable operation in strong electromagnetic interference environments.

[0047] Embodiment 2: The present invention provides a lithium-ion welding machine with integrated power factor correction and active rectification structure, which also includes a collaborative optimization unit of a multi-stage temperature compensation strategy and an adaptive arc stabilization algorithm.

[0048] The unit uses a distributed temperature sensor array, with PT1000 temperature sensors placed on the MOS tube heat dissipation substrate of the welding power control module, the IGBT tube housing of the charging management module, and the surface of the lithium battery cell. The main control chip collects temperature data in real time through multiple ADC channels and constructs a three-dimensional thermal field distribution model. When the local temperature gradient exceeds When the power is fully charged, the dynamic power distribution algorithm is started: the heat source is dispersed by adjusting the phase offset of the complementary PWM signal, and the dual PWM speed regulating fans of the air cooling system are linked to implement feedforward air volume adjustment according to the prediction results of the thermal field model, so as to control the junction temperature fluctuation of the power device within within the range.

[0049] The soft start mechanism of the charging management module is further optimized. On the basis of the traditional soft start circuit composed of resistors and relays, an intelligent pre-charging control system based on current slope detection is added. The main control chip monitors the bus capacitor charging current change rate in real time through the Hall sensor. When the current change rate exceeds 20A / ms, the graded current limiting protection is triggered: first, the pre-charging resistor value is reduced from the base value to the Step-by-step improvement At the same time, the relay pick-up threshold voltage is dynamically adjusted from 300V to 280V. This mechanism can effectively suppress the inrush current when charging large-capacity capacitors, and the measured inrush current peak value is reduced by 42%. In terms of charge balancing management, redundant windings are added to the secondary side of the high-frequency transformer, and auxiliary balancing power is generated through an independent rectifier circuit. When the voltage difference of the single battery is detected to exceed 50mV, the balancing current is accurately controlled by the MOS matrix. Accuracy range.

[0050] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A lithium-ion welding machine with integrated power factor correction and active rectification structure, characterized in that: include: Main control chip; Lithium battery power module; The welding power control module includes an active rectifier unit and a chopper unit. The active rectifier unit uses a dual-MOS tube complementary drive structure to achieve rectification in the continuous conduction mode, and the chopper unit adjusts the welding current through pulse width modulation technology. The charging management module integrates a power factor correction unit consisting of an IGBT tube, a fast recovery diode, and a BOOST inductor, and combines a half-bridge inverter topology with a high-frequency transformer to achieve charging voltage conversion; The voltage safety control module, consisting of a voltage divider network, a voltage comparator, and a trigger diode, dynamically switches the voltage at the welding machine terminal to a safety threshold; Multi-stage isolation sampling module, using isolation amplifier and differential circuit to achieve battery voltage isolation sampling; Asymmetric half-bridge power module generates multi-channel isolated power supply by integrating N+P type MOS tube driver chip; Human-computer interaction module, equipped with rotary encoder and segment code screen to realize digital setting and display of parameters; Among them, the charging management module is connected to the lithium battery power supply module, the welding power control module is driven by the main control chip signal, the voltage safety control module output signal is connected to the main control chip interrupt interface, the multi-level isolation sampling module is connected to the main control chip AD interface, the asymmetric half-bridge power supply module provides power for the IGBT drive, and the human-computer interaction module interacts with the main control chip through the communication interface.

2. A lithium-ion welding machine with integrated power factor correction and active rectification structure as claimed in claim 1, characterized in that: The gates of the dual MOS tubes in the welding power control module receive the complementary PWM signals output by the main control chip and set the dead time control logic; In the continuous conduction mode of the inductor current of the chopper unit, when the first MOS tube is turned on, the second MOS tube is turned off to realize the forward current path. When the second MOS tube is turned on, the first MOS tube is turned off to form a reverse freewheeling path. During the dead time, the body diode of the second MOS tube maintains the continuity of the inductor current. The chopper unit realizes the pulse width modulation output of the welding current by adjusting the duty cycle of the complementary PWM signal. The main control chip dynamically adjusts the dead time parameters according to the load current feedback to match the requirements of different welding processes.

3. A lithium-ion welding machine with integrated power factor correction and active rectification structure as claimed in claim 2, characterized in that: In the dual MOS tube complementary drive structure of the active rectifier unit, a pulse generator with a phase difference of 180° is built into the main control chip to generate two reference square wave signals. The two drive signals are connected to the gate of the MOS tube through independent gate drive circuits respectively. The second MOS tube body diode assumes the current freewheeling function during the dead time stage, and the main control chip is configured with an adaptive dead time compensation algorithm to optimize the dead time parameters in real time by detecting the phase offset of the inductor current zero crossing point.

4. A lithium-ion welding machine with integrated power factor correction and active rectification structure as claimed in claim 3, characterized in that: The independent gate drive circuit includes a current limiting resistor connected in series to the gate of the MOS tube and an RC buffer network connected in parallel between the gate and the source; The current limiting resistor value is set according to the MOS tube input capacitance and the output current capability of the driver chip, and the RC buffer network time constant is set to 1 / 15 of the complementary PWM signal period to suppress high-frequency oscillation. The adaptive dead-time compensation algorithm samples the peak-to-peak value of the inductor current ripple and combines it with the MOS tube junction temperature sensor data to build a three-dimensional compensation curve, dynamically correcting the dead-time parameters to balance switching losses and current continuity requirements.

5. A lithium-ion welding machine with integrated power factor correction and active rectification structure as claimed in claim 4, characterized in that: When the power factor correction unit and the active rectifier unit of the charging management module enter the linkage working mode, the main control chip synchronously controls the switching timing of the IGBT tube of the power factor correction unit and the MOS tube of the welding power control module, so that the inductive energy storage cycle of the BOOST boost circuit and the current freewheeling stage of the active rectifier unit are operated in phase shift; In the half-bridge inverter topology, the primary winding of the high-frequency transformer is connected in parallel with the output capacitor of the power factor correction unit, and the secondary winding is connected to the lithium battery charging port after center-tapped full-wave rectification. The main control chip adjusts the half-bridge inverter frequency according to the battery voltage sampling value to achieve constant current-constant voltage charging mode switching.

6. A lithium-ion welding machine with integrated power factor correction and active rectification structure as claimed in claim 5, characterized in that: In the linkage working mode, the main control chip controls the conduction duty cycle of the power factor correction unit IGBT tube and the welding power module MOS tube through time-sharing multiplexing drive signal bus. When a sudden increase in welding current demand is detected, the charging power is preferentially reduced to maintain bus voltage stability.

7. A lithium-ion welding machine with integrated power factor correction and active rectification structure as claimed in claim 1, characterized in that: The voltage safety control module comprises a voltage divider resistor network connected in series between the welding machine terminal and the ground, the voltage divider node is connected to the non-inverting input terminal of the voltage comparator, and the inverting input terminal is connected to the safety threshold voltage generated by the reference voltage source; When the welding terminal is open, the voltage at the voltage divider node exceeds the safety threshold voltage, triggering the comparator to flip. The output signal is transmitted to the main control chip after optical isolation to trigger the low voltage protection mode. At this time, the welding terminal voltage is clamped below the welding terminal safety voltage threshold. When welding current is detected, the main control chip automatically releases the voltage clamp and activates full power output.

8. The lithium-ion welding machine with integrated power factor correction and active rectification structure as claimed in claim 1, characterized in that: The multi-stage isolation sampling module adopts an isolation amplifier architecture based on capacitive coupling, with a voltage divider network and a differential input filter on the high-voltage side and a programmable gain instrumentation amplifier on the low-voltage side; The voltage divider network uses multiple stages of thick-film resistors connected in series and temperature compensation capacitors in parallel. The differential input filter consists of a common-mode choke and a π-type RC network. The output of the isolation amplifier is connected to the AD conversion channel of the main control chip after second-order active low-pass filtering. The main control chip has a built-in nonlinear correction algorithm to eliminate measurement errors caused by temperature drift of the voltage divider network.

9. A lithium-ion welding machine with integrated power factor correction and active rectification structure as claimed in claim 8, characterized in that: The high-voltage arm of the voltage divider network adopts a structure of multiple equal-value resistors in series, and each series node is connected in parallel with a high-frequency ceramic capacitor to form a distributed filtering network; The temperature compensation capacitor is a negative temperature coefficient film capacitor, the slope of its capacitance change matches the positive temperature coefficient of the voltage divider resistor, and together they form a temperature self-balancing voltage divider system; The nonlinear correction algorithm performs dynamic compensation by establishing a quartic polynomial model of the voltage divider ratio varying with temperature and combining it with real-time temperature sampling data.

10. The lithium-ion welding machine with integrated power factor correction and active rectification structure as claimed in claim 1, characterized in that: The asymmetric half-bridge power supply module uses an N+P type MOS tube integrated chip as a power switch device. Its gate drive signal is generated by a dedicated driver chip to generate a complementary square wave with opposite phases. When the drive signal is high, the N type MOS is turned on to form a forward energy transmission path. When the drive signal is low, the P type MOS is turned on to form a reverse energy recovery path. The secondary side of the transformer of the multi-channel isolated power supply adopts a dual-winding full-wave rectifier structure, each rectifier branch is connected in series with a magnetic bead filter and in parallel with a transient voltage suppression diode, and a balancing resistor network is connected across the positive and negative output terminals to maintain voltage symmetry.

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