阅读说明：本技术 一种辅助焊接励磁电源系统及多模态电流产生方法 (Auxiliary welding excitation power supply system and multi-mode current generation method ) 是由 石永华 梁焯永 王子顺 詹家通 陈金荣 于 2021-06-29 设计创作，主要内容包括：本发明公开了一种辅助焊接励磁电源系统及多模态电流产生方法,该辅助焊接磁电源系统包括依次连接的励磁电源主电路和数字化控制电路；励磁电源主电路的前端连接工频交流市电,励磁电源主电路的后端连接磁场发生装置；励磁电源主电路包括整流滤波模块和N路励磁电流输出通道,N≥2,数字化控制电路控制N路励磁电流通道独立输出或复合输出包括直流电流、脉冲电流、变极性脉冲电流、正弦电流及其复合电流等多种模态电流,同时通过通信模块实现根据焊接工艺的需求而在线动态调整励磁电流参数。本发明以一体化设计方案实现同时驱动多个磁场发生装置或者驱动更复杂的磁场发生装置,实现理想的磁场控制焊接过程,可控性和稳定性好,输出精度高。(The invention discloses an auxiliary welding excitation power supply system and a multi-mode current generation method, wherein the auxiliary welding excitation power supply system comprises an excitation power supply main circuit and a digital control circuit which are sequentially connected; the front end of the main excitation power supply circuit is connected with a power frequency alternating current commercial power, and the rear end of the main excitation power supply circuit is connected with a magnetic field generating device; the excitation power supply main circuit comprises a rectifying and filtering module and N excitation current output channels, N is more than or equal to 2, the digital control circuit controls the N excitation current channels to independently output or compositely output various modal currents including direct current, pulse current, variable polarity pulse current, sine current, composite current and the like, and meanwhile, the excitation current parameters are dynamically adjusted on line according to the requirements of a welding process through the communication module. The invention realizes the simultaneous driving of a plurality of magnetic field generating devices or the driving of more complicated magnetic field generating devices by an integrated design scheme, realizes an ideal magnetic field control welding process, and has good controllability and stability and high output precision.)

1. An auxiliary welding excitation power supply system is characterized by comprising an excitation power supply main circuit and a digital control circuit which are sequentially connected; the front end of the main excitation power supply circuit is connected with a power frequency alternating current commercial power, and the rear end of the main excitation power supply circuit is connected with a magnetic field generating device;

the excitation power supply main circuit comprises a rectification filter module and N excitation current output channels, N is more than or equal to 2, the rectification filter module is connected with each excitation current output channel, each excitation current output channel comprises a high-frequency inversion module, a high-frequency transformer, a quick rectification module and a polarity switching module which are sequentially connected, and the polarity switching module is connected with a magnetic field generating device through a voltage current Hall sensor.

2. The auxiliary welding excitation power supply system according to claim 1, wherein the digital control circuit comprises a digital control module, a PWM driving module, a voltage and current detection module, a fault detection module, a communication module and a human-computer interaction terminal; the PWM driving module comprises a PWM signal circuit, an IGBT driving circuit and a SiC driving circuit; the communication module comprises a CAN bus communication interface and an RS485 communication interface;

the man-machine interaction terminal is connected with the digital control module, the digital control module is connected with one end of the PWM signal circuit through the PWM port, the other end of the PWM signal circuit is connected with the IGBT drive circuit and the SiC drive circuit, the IGBT drive circuit is also connected with the high-frequency inversion module of the excitation power supply main circuit, and the SiC drive circuit is also connected with the polarity switching module of the excitation power supply main circuit; one end of the voltage and current detection module is connected with the magnetic field generation device through a voltage and current Hall sensor, and the other end of the voltage and current detection module is connected with the digital control module through an A/D input port; the fault detection module is connected with the digital control module through the GPIO port; the communication module is respectively connected with the CAN bus port and the RS485 port of the digital control module.

3. The auxiliary welding excitation power supply system according to claim 1, wherein the rectifier filter module comprises a rectifier chip BR1, a capacitor C1, a capacitor C2 and an inductor L1; the capacitor C1, the capacitor C2 and the inductor L1 form a pi-shaped filter unit;

the input end of a rectifying chip BR1 is connected with a 220V power frequency alternating current commercial power, the output end of the rectifying chip BR1 is connected with two ends of a capacitor C1, one end of the capacitor C1 is connected with one end of a capacitor C2 through an inductor L1, and the other end of the capacitor C1 is connected with the other end of a capacitor C2; two ends of the capacitor C2 are also connected with the high-frequency inversion module of each path of exciting current output channel;

the high-frequency inversion module comprises an IGBT power switch tube M1, an IGBT power switch tube M2, an IGBT power switch tube M3, an IGBT power switch tube M4, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6 and electricityContainer C_b1Capacitor C_b2The resistor R1, the resistor R2, the resistor R3 and the resistor R4;

two ends of the capacitor C2 are respectively connected to the drain of the IGBT power switch tube M1 and the source of the IGBT power switch tube M3, the source of the IGBT power switch tube M1 is connected with the drain of the IGBT power switch tube M1 through the capacitor C3 and the resistor R1 in sequence, the source of the IGBT power switch tube M2 is connected with the drain of the IGBT power switch tube M2 through the capacitor C4 and the resistor R4 in sequence, the source of the IGBT power switch tube M3 is connected with the drain of the IGBT power switch tube M3 through the capacitor C5 and the resistor R3 in sequence, the source of the IGBT power switch tube M4 is connected with the drain of the IGBT power switch tube M4 through the capacitor C6 and the resistor R4 in sequence, the drain of the IGBT power switch tube M4 is also connected with the drain of the IGBT power switch tube M4, the source of the IGBT power switch tube M4 is also connected with the drain of the IGBT power switch tube M4, the source electrode of the IGBT power switch tube M1 also passes through a capacitor C_b1One end of the primary coil of the high-frequency transformer is connected with a capacitor C_b2Is connected with a capacitor C at two ends_b1The source electrode of the IGBT power switching tube M2 is also connected with the other end of the primary coil of the high-frequency transformer; the secondary coil of the high-frequency transformer is connected with the fast rectification module;

the fast rectification module comprises a diode VD1, a diode VD2, a diode VD3 and a diode VD4, the diode VD1 and the diode VD3 are sequentially connected, the diode VD2 and the diode VD4 are sequentially connected, the cathode of the diode VD1 is connected with the cathode of the diode VD2, the cathode of the diode VD1 is further connected with a first tap of a secondary coil of the high-frequency transformer, the cathode of the diode VD1 is further connected with the polarity switching module through an inductor L2, the anode of the diode VD3 is connected with the anode of the diode VD4, the anode of the VD diode 3 is further connected with the polarity switching module through an inductor L3, and the cathode of the diode VD4 is connected with a third tap of the secondary coil of the high-frequency transformer; a second tap of a secondary coil of the high-frequency transformer is connected with the Hall sensor;

the polarity switching module comprises a switching tube Q1, a switching tube Q2, a switching tube Q3, a switching tube Q4, a resistor R5, a resistor R6, a capacitor C7 and a capacitor C8;

the emitter of the switching tube Q1 is connected with the collector of the switching tube Q3, the emitter of the switching tube Q2 is connected with the collector of the switching tube Q4, the collector of the switching tube Q1 is also connected with one end of an inductor L2, the emitter of the switching tube Q3 is also connected with one end of an inductor L3, the collector of the switching tube Q1 is also connected with the emitter of the switching tube Q3 sequentially through a resistor R5, a capacitor C7, a resistor R6 and a capacitor C8, the emitter of the switching tube Q1 and the emitter of the switching tube Q2, one end of the capacitor C7 is connected with a Hall sensor, and the output end of the Hall sensor is used as the output of each excitation current output channel.

4. The auxiliary welding excitation power supply system according to claim 1, wherein the digital control module employs a digital signal processor TMS320F 280049.

5. A multimode current generation method based on an auxiliary welding excitation power supply system is characterized by comprising a closed-loop constant current control method and a current subdivision control method, wherein multimode current comprises direct current, pulse current, variable polarity pulse current, sinusoidal current and composite current formed by combining two or three paths of current; the current generation process comprises the following steps:

the rectification filter module converts 220V power frequency commercial power into bus direct current, the bus direct current is input into at least one of N excitation current output channels of the excitation power supply main circuit, a high-frequency inversion module of the excitation current output channels converts the bus direct current into alternating square wave current on a primary coil of a high-frequency transformer, and the high-frequency transformer couples square wave current energy to a secondary output end of the high-frequency transformer; the fast rectification module converts the alternating square wave current at the secondary output end of the high-frequency transformer into smooth direct current; the polarity switching module converts the direct current into corresponding current according to the requirement of a preset output waveform.

6. The multi-modal current generation method of claim 5, wherein the closed-loop constant current control method comprises the steps of:

man-machine interactive terminal received by digital control modulePredetermined current parameter I of terminal transmission_grMeanwhile, the voltage and current detection module collects the current I at the output end of the voltage and current Hall sensor_gWill be current I_gConverted to a voltage U_gVoltage and current detection module for detecting voltage U_gTransmitting to a digital control module which transmits the voltage U_gConverted into corresponding acquisition current I_goAnd will collect current I_goAnd a predetermined current I_grComparing, adjusting the duty ratio of the PWM signal according to the comparison result by the digital control module, and collecting the current I_goGreater than a predetermined current I_grWhen the current I is collected, the duty ratio of the PWM signal is reduced_goLess than a predetermined current I_grIf so, increasing the duty ratio of the PWM signal; outputting the PWM signals to a PWM driving module after the operation of an anti-integral saturation PI algorithm, and controlling a high-frequency inversion module and a polarity switching module by the PWM driving module according to the duty ratio of the PWM signals, and repeating the operation; the output of the main circuit of the excitation power supply is changed by adjusting the duty ratio of the PWM signal, and finally the output excitation current is equal to the preset current I_grThe magnetic field generating device is driven to generate a magnetic field.

7. The multimodal current generation method according to claim 6, wherein the current subdivision control method comprises the steps of:

equally dividing a current cycle into N time intervals, wherein the time of each time interval is T/N, T is the current cycle time, and in the nth time interval, the current is presetWherein N is 1,2_mFor peak current, executing closed-loop constant current control process according to closed-loop constant current control method to output constant current with constant current valueI_nAn output current value corresponding to the nth period; gradually iterating the current value I of each time interval by an iteration method_nOutputting a predetermined pattern during a current cycleThe current of (2).

8. The multi-modal current generation method of claim 7, further comprising, when N ≧ 2: the digital control circuit controls the working states of the high-frequency inversion module and the polarity switching module, so that the N excitation current output channels are controlled to independently output or compositely output multi-mode current, direct current, pulse current, polarity-changing pulse current and sine current are independently output by three excitation current output channels, the composite current is output by two or three excitation current output channels in a combined mode, and when two paths of sine current are output in the combined mode and the phase shift angle is 90 degrees or 180 degrees, the composite current is called two-phase sine current; or, when the combination outputs three paths of sinusoidal currents and the phase shift angle is 120 degrees, the three-phase sinusoidal current is called as three-phase sinusoidal current.

9. The multi-modal current generation method according to claim 8, wherein the output of the direct current, the pulse current, and the variable polarity pulse current is controlled by a closed-loop constant current control method, and a peak current I is preset when the direct current is output_mThen executing a closed-loop constant-current control process; when the pulse current is output, the peak current I is preset_pSum base current I_bThen, respectively executing a closed-loop constant current control process in a peak value stage and a basic value stage; when the pulse current with variable polarity is output, the positive polarity peak current I is preset_p1And negative polarity peak current I_p2Then, respectively executing a closed-loop constant current control process in a positive polarity current stage and a negative polarity current stage; the sinusoidal current, the two-phase sinusoidal current and the three-phase sinusoidal current are output by adopting a current subdivision control method, and a peak current I is preset_mThen, executing a current subdivision control process; an output coupling closed-loop constant current control method and a current subdivision control method of compound current.

10. A multimodal current generation method according to claim 9, characterized in that a phase shift angle α exists between the different phase currents of the composite current, the phase shift angle α is controlled to generate different combinations of currents, when α is 0 °, the phase currents are output synchronously, when α is 180 °, the phase currents are output alternately, i.e. one phase current is at a maximum value and the other phase current is at a minimum value or a zero current state, when α is 90 °, there are three combinations of state currents, two phase currents are at a maximum value, one phase current is at a maximum value and the other phase current is at a minimum value or a zero current state, and both phase currents are at a minimum value.

Technical Field

The invention relates to the technical field of magnetic control welding, in particular to an auxiliary welding excitation power supply system and a multi-modal current generation method.

Background

The Keyhole-effect TIG (K-TIG) welding is a novel deep fusion welding technology which uses larger current to generate electric arc with high energy, good stiffness and strong penetration capacity on the basis of the traditional Tungsten argon arc welding (TIG), can realize one-pass penetration of a groove of a medium plate in the welding process, realizes the double-sided forming of single-sided welding and has high welding efficiency. A lock hole penetrating through the whole welded workpiece can be formed in the K-TIG welding process, and dynamic balance can be kept in the K-TIG welding pool under the action of liquid metal static pressure, liquid metal surface tension and electric arc pressure. However, when the novel efficient welding mode of K-TIG welding is adopted for welding, as the welding mode is a high-current and high-heat input welding mode, for low-carbon steel, the large heat input easily causes the crystal grains of the welding seam to be coarse, the mechanical property of the welding seam is poor, and the use requirement cannot be met.

The magnetic control welding technology is a novel welding technology which is gradually improved, the magnetic field is utilized to change the characteristics of an electric arc and the crystallization of a molten pool, not only is welding equipment simple and the input cost low, the energy consumption less, but also the process flow is reduced, so that the welding efficiency is improved, the welding quality is improved, and the like. The magnetic field forms include a transverse deflection magnetic field, a transverse rotating magnetic field, a longitudinal magnetic field and a sharp-angle magnetic field, and the excitation modes include direct current, alternating current, pulse and the like.

With the development of power electronic technology and magnetic control welding technology, people are more concerned about the development of novel magnetic field generating devices, and hope that an ideal magnetic field form is obtained through reasonable distribution and control of a space magnetic field, so that a welding arc is more effectively controlled, and a welding process is perfected. For the magnetic field generating device, many developers design the magnetic field device meeting the requirements according to their own needs, for example, application No. CN202011390594.3 entitled "a magnetic field generating device and a welding gun" proposes a magnetic field generating device, which includes a coil connector, a power supply, a wiring switching device and a control device, wherein the control device is respectively connected with the power supply and the wiring switching device, and controls the switching action of the wiring switching device and the switching of the power supply, thereby generating a transverse deflecting magnetic field, a transverse swinging magnetic field, a transverse rotating magnetic field or a sharp angle magnetic field. Because the magnetic field generating device needs to generate a plurality of magnetic field forms, a complex excitation power supply with multiple current outputs is needed for driving, or auxiliary components are added on the periphery of a common excitation power supply so as to realize the switching of the excitation current.

Different magnetic field generating devices have different required excitation power supply wiring modes and different excitation current waveforms. For an excitation power supply, some scholars propose different design schemes, for example, application No. CN201510053313.8, entitled "multifunctional magnetic field generation control circuit" proposes a multifunctional magnetic field generation control circuit, which includes a power supply, an adjustable resistor, a double H-bridge circuit module, a coil, a capacitor, a controllable switch, a switch control part and a signal source, the signal source generates a synchronous signal, the controllable switch in the double H-bridge circuit module is synchronously controlled by the switch control to generate an ON/OFF switching combination, so that the double H-bridge circuit modules can be independent of each other or can cooperate with each other to generate different pulse magnetic field current waveforms. The application number CN202010673192.8, the title of the invention, "a swinging magnetic field generating device and a multimode current generating method thereof", provides a swinging magnetic field generating device which is switched automatically and generates sinusoidal pulses in sequence, after a capacitor C is charged by a direct current power supply U each time, current is enabled to pass through coils L1, L2 and L3 in sequence under the action of a microcontroller to generate a swinging magnetic field.

Through analysis of the above cases and other related documents, the existing excitation power supply has the following limitations:

(1) the existing excitation power supply is mostly formed by combining components such as a common power supply, a capacitor and an inductor, and the like, and has poor controllability and stability: on one hand, the excitation power supply is built by using the discrete components, when the components are connected in a large number, wrong wires are easy to connect during wiring, and the problem of interference is easy to generate due to the fact that the wires are mutually inserted; on the other hand, when a certain component is in fault or abnormal or has poor contact, the excitation power supply cannot work normally or the output precision is not high. These conditions are the direct reason that the output precision and stability of the existing excitation power supply are not high.

(2) The existing excitation power supply has single output function and poor compatibility: either outputting a constant current or outputting a pulse current, and when switching to another mode current, the circuit topology structure is often required to be changed; in addition, different magnetic field generating devices are different in wiring mode, for example, a transverse deflection magnetic field can be driven by only one current, a rotating magnetic field can be driven by two or three currents, and if the magnetic field generating devices are to be replaced, the circuit topology structure is often changed. These conditions can cause heavy work to test and debug.

(3) The work of the existing excitation power supply mainly takes static parameters as main parts, and the adjustability is poor: in the working process, the excitation current parameter is often not changed, if the current parameter needs to be changed, the work needs to be stopped first, and the magnetic field parameter is restarted after the parameter is set, so that the requirement of selecting a proper magnetic field parameter according to the welding working condition in the welding process is difficult to meet. This causes a lot of trouble in the process research work.

Therefore, there is a need in the industry to develop an auxiliary welding excitation power supply system with high controllability and stability and capable of outputting multi-mode current.

Disclosure of Invention

In order to overcome the defects and shortcomings of the prior art, the invention provides an auxiliary welding excitation power supply system and a multi-mode current generation method, which overcome the defects and shortcomings of the conventional welding excitation power supply by an integrated design scheme, better drive increasingly abundant magnetic field generation devices and realize an ideal magnetic field control welding process.

In order to achieve the purpose, the invention adopts the following technical scheme:

an auxiliary welding excitation power supply system comprises an excitation power supply main circuit and a digital control circuit which are sequentially connected; the front end of the main excitation power supply circuit is connected with a power frequency alternating current commercial power, and the rear end of the main excitation power supply circuit is connected with a magnetic field generating device; the excitation power supply main circuit comprises a rectification filter module and N excitation current output channels, N is more than or equal to 2, the rectification filter module is connected with each excitation current output channel, each excitation current output channel comprises a high-frequency inversion module, a high-frequency transformer, a quick rectification module and a polarity switching module which are sequentially connected, and the polarity switching module is connected with a magnetic field generating device through a voltage current Hall sensor.

Preferably, the digital control circuit comprises a digital control module, a PWM driving module, a voltage and current detection module, a fault detection module, a communication module and a human-computer interaction terminal; the PWM driving module comprises a PWM signal circuit, an IGBT driving circuit and a SiC driving circuit, and the communication module comprises a CAN bus communication interface and an RS485 communication interface; the man-machine interaction terminal is connected with the digital control module, the digital control module is connected with one end of the PWM signal circuit through a PWM port, the other end of the PWM signal circuit is connected with the IGBT drive circuit and the SiC drive circuit, the IGBT drive circuit is also connected with the high-frequency inversion module of the excitation power supply main circuit, and the SiC drive circuit is also connected with the polarity switching module of the excitation power supply main circuit; one end of the voltage and current detection module is connected with the magnetic field generation device through a voltage and current Hall sensor, and the other end of the voltage and current detection module is connected with the digital control module through an A/D input port; the fault detection module is connected with the digital control module through the GPIO port; the communication module is respectively connected with a CAN bus port and an RS485 port of the digital control module, and excitation current parameters are dynamically adjusted on line according to the requirements of a welding process in the welding process.

Preferably, the rectifier filter module comprises a rectifier chip BR1, a capacitor C1, a capacitor C2 and an inductor L1; the capacitor C1, the capacitor C2 and the inductor L1 form a pi-shaped filter unit; the input end of a rectifying chip BR1 is connected with a 220V power frequency alternating current commercial power, the output end of the rectifying chip BR1 is connected with two ends of a capacitor C1, one end of the capacitor C1 is connected with one end of a capacitor C2 through an inductor L1, and the other end of the capacitor C1 is connected with the other end of a capacitor C2; two ends of the capacitor C2 are also connected with the high-frequency inversion module of each path of exciting current output channel;

the high-frequency inversion module comprises an IGBT power switch tube M1, an IGBT power switch tube M2, an IGBT power switch tube M3, an IGBT power switch tube M4, a capacitor C3, a capacitor C4, a capacitor C5, a capacitor C6 and a capacitor C6_b1Capacitor C_b2The resistor R1, the resistor R2, the resistor R3 and the resistor R4; two ends of the capacitor C2 are respectively connected to the drain of the IGBT power switch tube M1 and the source of the IGBT power switch tube M3, the source of the IGBT power switch tube M1 is connected to the drain of the IGBT power switch tube M1 through the capacitor C3 and the resistor R1 in sequence, the source of the IGBT power switch tube M2 is connected to the drain of the IGBT power switch tube M2 through the capacitor C4 and the resistor R4 in sequence, the source of the IGBT power switch tube M3 is connected to the drain of the IGBT power switch tube M3 through the capacitor C5 and the resistor R3 in sequence, the source of the IGBT power switch tube M4 is connected to the drain of the IGBT power switch tube M4 through the capacitor C6 and the resistor R4 in sequence, the drain of the IGBT power switch tube M4 is also connected to the drain of the IGBT power switch tube M4, the source of the IGBT power switch tube M4 is also connected to the drain of the IGBT power switch tube M4, the source electrode of the IGBT power switch tube M1 also passes through a capacitor C_b1One end of the primary coil of the high-frequency transformer is connected with a capacitor C_b2Is connected with a capacitor C at two ends_b1The source electrode of the IGBT power switching tube M2 is also connected with the other end of the primary coil of the high-frequency transformer; the secondary coil of the high-frequency transformer is connected with the fast rectification module;

the fast rectification module comprises a diode VD1, a diode VD2, a diode VD3 and a diode VD4, the diode VD1 and the diode VD3 are sequentially connected, the diode VD2 and the diode VD4 are sequentially connected, the cathode of the diode VD1 is connected with the cathode of the diode VD2, the cathode of the diode VD1 is further connected with a first tap of a secondary coil of the high-frequency transformer, the cathode of the diode VD1 is further connected with the polarity switching module through an inductor L2, the anode of the diode VD3 is connected with the anode of the diode VD4, the anode of the diode VD3 is further connected with the polarity switching module through an inductor L3, and the cathode of the diode VD4 is connected with a third tap of the secondary coil of the high-frequency transformer; a second tap of a secondary coil of the high-frequency transformer is connected with the Hall sensor; the polarity switching module comprises a switching tube Q1, a switching tube Q2, a switching tube Q3, a switching tube Q4, a resistor R5, a resistor R6, a capacitor C7 and a capacitor C8; an emitter of the switching tube Q1 is connected with a collector of the switching tube Q3, an emitter of the switching tube Q2 is connected with a collector of the switching tube Q4, a collector of the switching tube Q1 is further connected with one end of an inductor L2, an emitter of the switching tube Q3 is further connected with one end of an inductor L3, a collector of the switching tube Q1 is further connected with an emitter of the switching tube Q3 sequentially through a resistor R5, a capacitor C7, a resistor R6 and a capacitor C8, an emitter of the switching tube Q1 and an emitter of the switching tube Q2, one end of the capacitor C7 is connected with a hall sensor, and an output end of the hall sensor is used as an output of each excitation current output channel.

Preferably, the digital control module employs a digital signal processor TMS320F 280049.

A multimode current generation method based on an auxiliary welding excitation power supply system comprises a closed-loop constant current control method and a current subdivision control method, wherein multimode current comprises direct current, pulse current, variable polarity pulse current, sinusoidal current and composite current formed by combining two or three paths of current; the current generation process comprises the following steps: the rectification filtering module converts 220V power frequency commercial power into bus direct current; the direct current of the bus is input into at least one of N excitation current output channels of the excitation power supply main circuit, the high-frequency inversion module of the excitation current output channels converts the direct current of the bus into alternating square wave current on a primary coil of a high-frequency transformer, and the high-frequency transformer couples the square wave current energy to a secondary output end of the high-frequency transformer; the fast rectification module converts the alternating square wave current at the secondary output end of the high-frequency transformer into smooth direct current; the polarity switching module converts the direct current into corresponding current according to the requirement of a preset output waveform.

Preferably, after the rectifying and filtering module converts the power frequency commercial power into the bus direct current, a closed-loop constant current control process is executed by a closed-loop constant current control method, and the closed-loop constant current control process comprises the following stepsThe method comprises the following steps: the digital control module receives a preset current parameter I transmitted by a man-machine interaction terminal_grMeanwhile, the voltage and current detection module acquires the current I at the output end of the voltage and current Hall sensor_gWill be current I_gConverted to a voltage U_gVoltage and current detection module for detecting voltage U_gTransmitting to a digital control module which transmits the voltage U_gConverted into corresponding acquisition current I_goAnd will collect current I_goAnd a predetermined current I_grComparing, adjusting the duty ratio of the PWM signal according to the comparison result and the digital control module when collecting the current I_goGreater than a predetermined current I_grWhen the current I is collected, the duty ratio of the PWM signal is reduced_goLess than a predetermined current I_grIf so, increasing the duty ratio of the PWM signal; outputting the PWM signals to a PWM driving module after the operation of an anti-integral saturation PI algorithm, and controlling a high-frequency inversion module and a polarity switching module by the PWM driving module according to the duty ratio of the PWM signals, and repeating the operation; the output of the main circuit of the excitation power supply is changed by adjusting the duty ratio of the PWM signal, and finally the output excitation current is equal to the preset current I_grThe magnetic field generating device is driven to generate a magnetic field.

Preferably, after the rectifying and filtering module converts the power frequency commercial power into the bus direct current, the current subdivision control process is executed by a current subdivision control method, and the current subdivision control process includes the following steps: equally dividing a current cycle into N time intervals, wherein the time of each time interval is T/N, T is the current cycle time, and in the nth time interval, the current is presetWherein N is 1,2_mFor peak current, executing closed-loop constant current control process according to closed-loop constant current control method to output constant current with constant current valueI_nAn output current value corresponding to the nth period; gradually iterating the current value I of each time interval by an iteration method_nAt a current ofIn the period, the current of the preset shape is output.

Preferably, when N ≧ 2, the multimodal current generation method further includes: the digital control circuit controls the working states of the high-frequency inversion module and the polarity switching module so as to control the N excitation current output channels to independently output or compositely output the multimode current, the direct current, the pulse current, the polarity-variable pulse current and the sine current are independently output by the three excitation current output channels, the composite current is output by the combination of the two or three excitation current output channels, and when the two paths of sine currents are output in a combined manner and the phase shift angle is 90 degrees or 180 degrees, the composite current is called two-phase sinusoidal current; or, when the combination outputs three paths of sinusoidal currents and the phase shift angle is 120 degrees, the three-phase sinusoidal current is called as three-phase sinusoidal current.

Preferably, the output of the direct current, the pulse current and the variable polarity pulse current adopts a closed-loop constant current control method, and when the direct current is output, the peak current I is preset_mThen, a closed-loop constant current control process is executed by a closed-loop constant current control method; when the pulse current is output, the peak current I is preset_pSum base current I_bThen, a closed-loop constant current control process is executed in a peak value stage and a basic value stage respectively through a closed-loop constant current control method; when the pulse current with variable polarity is output, the positive polarity peak current I is preset_p1And negative polarity peak current I_p2Then, a closed-loop constant current control process is executed in the positive polarity current stage and the negative polarity current stage respectively through a closed-loop constant current control method; the sinusoidal current, the two-phase sinusoidal current and the three-phase sinusoidal current are output by adopting a current subdivision control method, and the peak current I is preset_mThen, executing a current subdivision control process by a current subdivision control method; an output coupling closed-loop constant current control method and a current subdivision control method of composite current.

Preferably, phase shifting angles α exist between different phase currents of the composite current, the phase shifting angles α are controlled to generate different combinations of currents, when α is 0 °, the phase currents are synchronously output, when α is 180 °, the phase currents are alternately output, that is, one phase current is at a maximum value, the other phase current is at a minimum value or a zero current state, when α is 90 °, three state combinations of currents are provided, the two phase currents are at a maximum value, the one phase current is at a maximum value, the other phase current is at a minimum value or a zero current state, and the two phase currents are at a minimum value.

Compared with the prior art, the invention has the following advantages and beneficial effects:

(1) the excitation power supply main circuit comprises a rectification filter module and N excitation current output channels, and can realize multi-modal excitation current output through the combined action of each channel or multiple channels, each modal excitation current has multiple current parameters, and the current mode and the current parameters can be adjusted through preset current parameters received by a human-computer interaction terminal and current collected by a voltage and current detection module to generate multiple combined current modes, so that abundant test scheme designs are provided for magnetic control technology and welding process research, and an effective way is provided for optimization work of a welding process and welding quality. Meanwhile, a single channel or multiple channels can be selected to act independently or multiple channels can be selected to act compositely according to actual needs, so that a plurality of magnetic field generating devices can be driven simultaneously or more complex magnetic field generating devices can be driven conveniently.

(2) The excitation power supply system can directly generate the required excitation current without external electronic components, has simple structure and small volume, and can save a large amount of space; and a digital multi-mode current generation method is adopted, so that the control is flexible, and the output precision and stability of the excitation power supply are high.

(3) The excitation power supply system provides an external communication interface, and dynamically adjusts excitation current parameters on line according to the requirements of a welding process; meanwhile, when the software code is required to be modified, the software code can be updated through the external communication interface, so that the operation of disassembling the computer is avoided, and the efficiency is greatly improved for the test and debugging work.

(4) The excitation power supply system related by the invention adopts a digital control technology, is easy and convenient for function development and secondary development, provides a hardware basis for a plurality of current channels, and can easily develop the excitation current meeting the actual requirement by modifying software codes according to the actual working condition requirement.

Drawings

FIG. 1 is a schematic diagram of the auxiliary welding excitation power system of the present invention;

fig. 2 is a specific circuit diagram of one excitation current output channel of the main circuit of the excitation power supply of the invention;

FIG. 3 is a schematic diagram of the constant current closed loop control process of the present invention;

FIG. 4 is a schematic diagram of the operation of the current subdivision control method of the present invention;

FIG. 5 is a schematic diagram of a DC current waveform of the present invention;

FIG. 6 is a schematic diagram of a pulsed current waveform of the present invention;

FIG. 7(a) is a schematic diagram of a variable polarity pulsed current waveform without zero current according to the present invention;

FIG. 7(b) is a schematic diagram of a zero current polarity-changing pulse current waveform of the present invention;

FIG. 8(a) is a schematic of a full wave sinusoidal current waveform of the present invention;

FIG. 8(b) is a schematic diagram of a half-wave sinusoidal current waveform of the present invention;

FIG. 9 is a schematic diagram of a two-phase sinusoidal current waveform of the present invention;

FIG. 10 is a schematic diagram of a three-phase sinusoidal current waveform of the present invention;

FIG. 11 is a schematic diagram of the composite current waveform of the three-way current combination of the present invention;

FIG. 12 is a flow chart of the pulsed current waveform output process of the present invention;

FIG. 13 is a flow chart of the sinusoidal current waveform output process of the present invention;

fig. 14 is a flow chart of the composite current waveform output process of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

As shown in fig. 1, the auxiliary welding excitation power supply system comprises an excitation power supply main circuit and a digital control circuit which are sequentially connected, wherein the front end of the excitation power supply main circuit is connected with a power frequency alternating current mains supply, and the rear end of the excitation power supply main circuit is connected with a magnetic field generating device; the excitation power supply main circuit comprises a rectification filter module and 3 excitation current output channels, the rectification filter module is connected with each excitation current output channel, each excitation current output channel comprises a high-frequency inversion module, a high-frequency transformer, a quick rectification module and a polarity switching module which are sequentially connected, and the polarity switching module is connected with the magnetic field generating device through a voltage current Hall sensor. The digital control circuit comprises a digital control module, a PWM (pulse-width modulation) driving module, a voltage and current detection module, a fault detection module, a man-machine interaction terminal and a communication module, wherein the PWM driving module comprises a PWM signal circuit, an IGBT driving circuit and a SiC driving circuit; the human-computer interaction terminal is connected with the digital control module through a serial port communication interface RS 232; the communication module comprises a CAN bus communication interface and an RS485 communication interface which are respectively connected with a CAN bus port and an RS485 port of the digital control module; the digital control module is connected with other control systems through a communication module. The digital control module is connected with one end of a PWM signal circuit through a PWM port, the other end of the PWM signal circuit is connected with an IGBT drive circuit and a SiC drive circuit, the IGBT drive circuit is also connected with a high-frequency inversion module of an excitation power supply main circuit, and the SiC drive circuit is also connected with a polarity switching module of the excitation power supply main circuit; one end of the voltage and current detection module is connected with the magnetic field generation device through the voltage and current Hall sensor, the other end of the voltage and current detection module is connected with the digital control module through an A/D input port, and the voltage and current detection module detects the voltage and current at the output end of the voltage and current Hall sensor and transmits the detected voltage and current data to the digital control module; the fault detection module comprises overvoltage and undervoltage detection, overcurrent detection, over-temperature detection and the like, one end of the fault detection module is connected with the rectification filter module and the voltage and current detection module, the other end of the fault detection module is connected with the GPIO port of the digital control module, if no fault exists, the GPIO port is at a high level, and if the fault exists, the GPIO port is at a low level.

It should be noted that the main circuit of the excitation power supply adopts a high-frequency inverter module, a high-frequency transformer, a fast rectifier module and a polarity switching module which have the same topological structure, so as to form three excitation current output channels; the high-frequency inversion module of each channel is controlled by an independent IGBT drive circuit, and the polarity switching module is controlled by an independent SiC drive circuit, namely three IGBT drive circuits and three SiC drive circuits are respectively arranged; the IGBT driving circuit adopts the existing module; the SiC driving circuit adopts a grid driver UCC21750 of TI company, and the hardware circuit and the peripheral circuit adopt the design proposal recommended by TI official.

In this embodiment, the digital control module may adopt an ARM control chip, and may also adopt a DSP control chip or an MCU control chip, and the preferred DSP control chip digital signal processor TMS320F280049 of this embodiment, and the digital signal processor TMS320F280049 that uses includes peripheral on the chip: general input/output interface GPIO, pulse width modulation signal channel PWM, analog-to-digital converter ADC, universal asynchronous receiver/transmitter UART, controller area network transceiver CAN and RS 845. The digital control module serial port communication interface RS232 receives data such as the mode, the current parameter and the like of the exciting current from the man-machine interaction terminal, is connected with the man-machine interaction terminal or other control systems through the CAN bus communication interface or the RS485 communication interface, and dynamically adjusts the exciting current parameter on line according to the requirements of the welding process.

As shown in fig. 2, the rectifying and filtering module includes a pi-type filtering module composed of a rectifying module BR1, a capacitor C1, a capacitor C2, and an inductor L1; the high-frequency inversion module adopts four IGBT power switching tubes M1, M2, M3 and M4 to form a full-bridge topological structure, and each switching tube is connected with a group of RC filter modules in parallel; the high-frequency transformer T has two taps at the front end and three taps at the rear end, and a capacitor C is used between the high-frequency inversion module and the high-frequency transformer_b1/C_b2Coupling, eliminating the influence of the direct current on the high-frequency transformer; the fast rectification module adopts four fast recovery diodes VD1, VD2, VD3,VD4, forming a full-bridge topology; the polarity switching module adopts SiC power switch tubes, the topological structure of the polarity switching module is in series connection, each end is connected with a group of RC filter modules in parallel, the same side end adopts a parallel structure, the redundancy design is realized, and the current output power is increased, for example, the switch tubes Q1 and Q2 are connected in parallel, the switch tubes Q3 and Q4 are connected in parallel, and the switch tubes Q1/Q2 and the switch tubes Q3/Q4 can not be conducted at the same time but are alternatively conducted; two inductors L2, L3 are connected in series between the fast rectification module and the polarity switching module to provide stable direct current, and the combination of the two provides an output channel for positive and negative polarity current switching, and the specific process is as follows: when the switching tube Q1/Q2 is switched on and the switching tube Q3/Q4 is switched off, if the output current of the high-frequency transformer is positive, negative and positive, the current flows out from an upper tap at the rear end of the high-frequency transformer, sequentially flows into the positive pole of the load through the diode VD1, the inductor L2 and the switching tube Q1/Q2, and then flows back to the middle tap of the high-frequency transformer from the negative pole of the load, and the circuit outputs positive-polarity current; if the output current of the high-frequency transformer is positive, the current flows out from a lower tap at the rear end of the high-frequency transformer, sequentially flows into the anode of the load through a diode VD2, an inductor L2 and a switching tube Q1/Q2, then flows back to a middle tap of the high-frequency transformer from the cathode of the load, and the circuit outputs positive current; when the switching tube Q3/Q4 is switched on and the switching tube Q1/Q2 is switched off, if the output current of the high-frequency transformer is up-positive and down-negative, the current flows into the negative pole of the load from the middle tap of the high-frequency transformer, then flows out from the positive pole of the load, sequentially passes through the switching tube Q3/Q4, the inductor L3 and the diode VD4, and then flows back to the back-end down-tap of the high-frequency transformer, and the circuit outputs negative-polarity current; if the output current of the high-frequency transformer is positive, the current flows into the negative electrode of the load from the middle tap of the high-frequency transformer, then flows out from the positive electrode of the load, sequentially passes through a switching tube Q3/Q4, an inductor L3 and a diode VD3, and then flows back to the upper tap of the rear end of the high-frequency transformer, and the circuit outputs negative-polarity current.

The basic working principle of the main circuit of the excitation power supply is as follows: the rectification filtering module converts 220V power frequency commercial power into bus direct current, and inputs the bus direct current into at least one of 3 excitation current output channels of the excitation power supply main circuit; the high-frequency inversion module of the exciting current output channel converts the direct current of the bus into alternating square wave current on the primary side of the high-frequency transformer, the frequency of the alternating square wave current can reach 20kHz, the constant current characteristic adjustment can be realized by controlling the conduction duty ratio of an IGBT power switching tube, and the high-frequency transformer couples the square wave current energy to the secondary output end of the high-frequency transformer; the fast rectification module converts the alternating square wave current at the secondary output end of the high-frequency transformer into smooth direct current through a fast recovery diode and a filter inductor; the polarity switching module converts direct current into positive and negative polarity current according to the requirements of output waveforms.

A multimode current generation method based on an auxiliary welding excitation power supply system comprises a closed-loop constant current control method and a current subdivision control method, wherein multimode current comprises direct current, pulse current, variable polarity pulse current, sinusoidal current and composite current formed by combining two or three paths of current.

Fig. 3 is a schematic diagram of a closed-loop constant-current control process, and as shown in fig. 3, the digital control module, the PWM driving module, the high-frequency inverter module, the high-frequency transformer, the fast rectifier module, the polarity switching module, and the voltage/current detection module form a constant-current closed-loop control loop, and the working principle is as follows: the digital control module receives a preset current parameter I according to the man-machine interaction terminal_grAnd the current I collected by the voltage and current detection module_gControlling the conduction duty ratio of a GBT power switch tube of the high-frequency inversion module to realize constant-current characteristic regulation, and coupling square wave current energy to a secondary output end of the high-frequency transformer; the fast rectification module converts the alternating square wave current into smooth direct current; the polarity switching module converts the direct current into corresponding current according to the requirement of a preset output waveform.

The specific process of closed-loop constant current control is as follows: the digital control module receives a preset current parameter I transmitted by a man-machine interaction terminal or other control systems_grAnd simultaneously the voltage and current Hall sensor collects the current I of the output end_gAnd the current I is processed by a signal processing circuit_gConverting to a voltage U recognizable by the circuit_gVoltage U_gIs transmitted to a digital control module through a signal processing circuitThe digital control module reads the data of the A/D input port and converts the data into corresponding acquisition current I through a software program_goWill collect a current I_goAnd a predetermined current I_grComparing, controlling the duty ratio of PWM signal according to the comparison result, and collecting current I_goGreater than a predetermined current I_grWhen the current I is collected, the duty ratio of the PWM signal is reduced_goLess than a predetermined current I_grIf so, increasing the duty ratio of the PWM signal; outputting a required PWM signal after the operation of an integral saturation prevention PI algorithm, transmitting the PWM signal to a PWM driving module, controlling the on-off of an IGBT power switching tube M1/M2/M3/M4 of a high-frequency inversion module by the PWM driving module according to the duty ratio of the PWM signal, increasing the on-time and the on-current of the IGBT power switching tube when the duty ratio of the PWM signal is increased, and shortening the on-time and reducing the on-current of the IGBT power switching tube when the duty ratio of the PWM signal is reduced; the conduction current sequentially passes through the high-frequency transformer, the rapid rectification module and the polarity switching module and reaches the output end. The output current of the main circuit of the power supply is changed by adjusting the duty ratio of the PWM signal, and finally the output current I is enabled to be_gEqual to a predetermined current I_gr。

As shown in fig. 4, which is a schematic view of the working principle of the current subdivision control method, after the rectifying and filtering module converts the 220V power frequency commercial power into the bus direct current, the current subdivision control process is executed by the current subdivision control method, and the current subdivision control process includes the following steps: equally dividing a current cycle into N time intervals, wherein each time interval is equal to T/N, T is cycle time, and in the nth time interval, the current I is preset_grIs arranged asWherein N is 1,2_mIs peak current, f is current frequency, and the closed-loop constant current process is executed according to the closed-loop constant current control method to output constant current with the constant current valueI_nCurrent corresponding to nth periodThe value is obtained. Gradually iterating the current value I of each time interval by an iteration method_nAnd in a current period, if the output current changes according to a sine value, the sine current is output. In fact, the current frequency of the sinusoidal current generated by the current subdivision method is limited, for example, the equal fraction value N is 1000, and assuming that the frequency of the PWM signal generated by the digital control module is 20kHz, the frequency of the sinusoidal current does not exceed 20 Hz; if the value N is 100, the frequency of the sinusoidal current does not exceed 200Hz, and thus it can be seen that the smaller the value N is, the larger the frequency of the sinusoidal current is, and when the value N becomes smaller, the output control accuracy of the sinusoidal current is reduced, and the specific value of the equal value N should comprehensively consider the actual demand and the use condition of the component materials.

In this embodiment, the digital control circuit controls the working states of the high-frequency inverter module and the polarity switching module, so as to control the three paths of exciting currents to output a multi-mode current, that is, the channels independently output exciting currents or combine to output a composite exciting current.

As shown in fig. 5-6, fig. 7(a) -7 (b), fig. 8(a) -8 (b), and fig. 9-11, the multi-modal current includes a composite current formed by combining a direct current, a pulse current, a variable polarity pulse current, a sinusoidal current, and two or three currents, and particularly, when the combination outputs two sinusoidal currents with a phase shift angle of 90 ° or 180 °, the current is called a two-phase sinusoidal current; or, when the combination outputs three paths of sinusoidal currents and the phase shift angle is 120 degrees, the three-phase sinusoidal current is called as three-phase sinusoidal current. The output of the direct current, the pulse current and the variable polarity pulse current adopts a closed-loop constant-current control method, and when the direct current is output, the peak current I is preset_mThen, executing a closed-loop constant-current control process by a closed-loop constant-current control method; when the pulse current is output, the peak current I is preset_pSum base current I_bThen, a closed-loop constant current control process is executed in a peak value stage and a basic value stage respectively through a closed-loop constant current control method; when the variable polarity pulse current is output, the positive polarity peak current I is preset_p1And negative polarity peak current I_p2Then, closed-loop constant current control is executed by a closed-loop constant current control method in the positive polarity current stage and the negative polarity current stage respectivelyA process; the sinusoidal current, the two-phase sinusoidal current and the three-phase sinusoidal current are output by adopting a current subdivision control method, and a peak current I is preset_mThen, executing a current subdivision control process by a current subdivision control method; an output coupling closed-loop constant current control method and a current subdivision control method of composite current.

When the three excitation current output channels independently output or compositely output, the current channel setting adopts a priority level method, the three-phase sinusoidal current is preferred, the two-phase sinusoidal current is the second order, the excitation current of four modes of direct current, pulse current, variable polarity pulse current and sinusoidal current are of the same level, for example, when the output excitation current includes three-phase sinusoidal current, preferentially setting three-phase sinusoidal current parameters and setting other modal current parameters, if the output exciting current does not include three-phase sinusoidal current but includes two-phase sinusoidal current, preferentially setting two-phase sinusoidal current parameters, and setting other modal current parameters, if the output exciting current does not comprise three-phase sinusoidal current and two-phase sinusoidal current, and determining current channels and current parameters of the excitation current in four modes of direct current, pulse current, variable polarity pulse current and sinusoidal current according to the welding working condition and the magnetic field generating device.

The switching between different mode exciting currents adopts mode identification mode, the mode identification corresponds to the control subprogram of exciting current, for example, mode 1 corresponds to the direct current subprogram, and its parameters include constant current I_m(ii) a Mode 2 corresponds to a pulse current subroutine whose parameters include peak current I_pBase current I_bTime of peak value T_pAnd pulse frequency f; mode 3 for the variable polarity pulse current subroutine, the parameters include the positive polarity peak current I_p1Negative polarity peak current I_p2Positive polarity peak time T_p1Zero current time t_DAnd pulse frequency f, the polarity-changing pulse current comprises a pulse current without zero current transition and a pulse current with zero current transition_DOutputting non-zero current transition polarity-change pulse current when being zero, and when t_DOutputting transition polarity-changing pulse current with zero current when the current is not zero; mode 4 corresponds to sinusoidal currentA subroutine whose parameters include the peak current I_pAnd a pulse frequency f, wherein the sinusoidal current comprises a half-wave sinusoidal current and a full-wave sinusoidal current, the full-wave sinusoidal current is output when the polarity switching module switching tube Q1/Q2 and the switching tube Q3/Q4 are alternately switched on, and the half-wave sinusoidal current is output in two cases: firstly, when the positive half cycle and the negative half cycle are carried out, the switch tube Q1/Q2 of the polarity switching module is conducted, the switch tube Q3/Q4 is cut off, and at the moment, positive polarity sinusoidal current is output; secondly, during a positive half cycle, the switching tube Q1/Q2 of the polarity switching module is turned on, the switching tube Q3/Q4 is turned off, and at this time, a positive sine current is output, during a negative half cycle, the switching tube Q1/Q2 and the switching tube Q3/Q4 are simultaneously turned off, and at this time, no current is output, and in this embodiment, the first case is preferably considered; mode 5 corresponds to a two-phase sinusoidal current subroutine whose parameters include peak current I_m1Peak current I_m2Frequency f and phase angle alpha, in particular, the peak currents of the two currents may be equal, i.e. I_m1＝I_m2(ii) a Mode 6 corresponds to a three-phase sinusoidal current subroutine whose parameters include peak current I_m1Peak current I_m2Peak current I_m3The current frequency f and the phase angle alpha, in particular, the peak currents of the three currents may be equal, i.e. I_m1＝I_m2＝I_m3(ii) a Mode 7 corresponds to a composite current subroutine including three different currents, three same currents, two same currents, 1 different current, two phase currents and 1 different current, in mode 7, corresponding current modes and current parameters can be set, as shown in fig. 11, a three-way output composite current waveform combining a pulse current and a two-phase sinusoidal current, where channel 1 and channel 2 are set as two-phase sinusoidal current output channels, and channel 3 is set as a pulse current output channel, where the current parameters include a two-phase sinusoidal current peak current I_m1Peak current I_m2Frequency of current f₁Phase angle alpha and peak current I of pulse current_pBase current I_bTime of peak value T_pAnd the pulse frequency f₂。

The digital control module receives data such as a current mode and current parameters sent by a human-computer interaction terminal to generate a control time sequence for presetting excitation current output, wherein the control time sequence for the excitation current output comprises a direct current subprogram, a pulse current subprogram, a polarity-variable pulse current subprogram, a sinusoidal current subprogram, a two-phase sinusoidal current subprogram, a three-phase sinusoidal current subprogram and a composite current subprogram; and the control time sequence of the exciting current output optimizes the logic time sequence of the preset current control subprogram according to the current priority level when the three output channels independently output or compositely output.

The present embodiment describes the generation process of the pulse current, the sinusoidal current and the composite current in detail as follows:

as shown in FIG. 12, which is a working flow chart of the pulse current subroutine, the digital control module reads the current parameters transmitted by the human-machine interaction terminal or other control systems, and sets the current as the peak current I_pThen starting a timer to time the peak time T_pAt peak time T_pThe closed-loop constant-current control program is executed in an internal and cyclic mode, and the execution time T is_pThen, the current is set as the base current I_bThen starting a timer to time the base value time T_bAt a base time T_bInner (T)_b＝T-T_pThe period time T is 1/f), a closed-loop constant-current control program is circularly executed, and the execution time T is_bThen, whether the current parameter or the current mode is adjusted is judged, if the current parameter or the current mode does not need to be adjusted, the current is set as the peak current I_pCircularly executing the control process; if the current parameter needs to be adjusted, the current parameter is reset, and the current is set as the peak current I after the current is adjusted again_pCircularly executing the control process; and if the current mode needs to be adjusted, entering a control time sequence subprogram of the corresponding current mode.

As shown in fig. 13, which is a flow chart of the sinusoidal current subroutine, the digital control module reads the current parameters transmitted by the human-computer interaction terminal or other control systems, then starts the timer, executes the control program of the first half period of the sinusoidal current in the first half period of the period time T, and executes the control program of the second half period of the sinusoidal current in the second half period of the period time T;

the sinusoidal current first half cycle control program is as follows: firstly, setting the current as 0A, setting the iteration number value n as 0, controlling the switch tube Q1/Q2 of the polarity switching module to be switched on, switching the switch tube Q3/Q4 to be switched off, then starting a timer, timing the interval time delta t, circularly executing a closed-loop constant-current control program in the interval time delta t, entering a current parameter iteration process and circularly executing the iteration process after the execution time delta t, namely adding 1 to the iteration number value n, and setting the current as I_msin (2 pi. N/N), then starting a timer, circularly executing a closed-loop constant-current control program, ending the iteration process when the iteration value N is more than or equal to N/2, and switching to a sinusoidal current latter half-period control program;

the control program of the second half period of the sine current is as follows: firstly, setting the current as 0A, setting the iteration number value n as 0, controlling the switch tube Q1/Q2 of the polarity switching module to be cut off, switching the switch tube Q3/Q4 to be switched on, then starting a timer, timing the interval time delta t, circularly executing a closed-loop constant-current control program in the interval time delta t, entering a current parameter iteration process and circularly executing the iteration process after executing the time delta t, namely adding 1 to the iteration number value n, and setting the current as I_msin (2 pi · N/N), then starting a timer, circularly executing a closed-loop constant-current control program, ending the iterative process when the iterative value N is more than or equal to N/2, judging whether to adjust the current parameter or the current mode, switching to the control program of the first half period of the sinusoidal current if the current parameter and the current mode are not required to be adjusted, and circularly executing the control program of the first half period of the sinusoidal current and the control program of the second half period of the sinusoidal current; if the current parameters need to be adjusted, resetting the current parameters, and executing the first half period control program and the second half period control program of the sinusoidal current in a recycling manner; and if the current mode needs to be adjusted, entering a control time sequence subprogram of the corresponding current mode.

As shown in fig. 14, in this embodiment, the pulse current and two-phase sinusoidal current composite output is selected as a case to describe the working process of the composite current output, and the working flow of the output composite current is as follows: the digital control module reads current parameters transmitted by a human-computer interaction terminal or other control systems, and firstly, the current I is converted into a digital control signal₁Current I₂And current I₃All set to 0A, the number of iterations n set to 0, and then the current I₃Set as the peak current I_pThen the timer is started again to time the peak time T_pAt peak time T_pIn which the current I is executed first₃A closed-loop constant current control program is executed, and then a two-phase sinusoidal current control program is executed;

the two-phase sinusoidal current control procedure is as follows: firstly executing a current polarity judging program 1, then starting a timer, timing an interval time delta t, circularly executing a closed-loop constant-current control program in the interval time delta t, judging whether an iteration number N is less than N or not after the execution time delta t, if N is less than N, adding 1 to the iteration number N, otherwise, setting the iteration number N as 0, and then, setting a current I₁Is set to I_m1sin (2 π N/N), Current I₂Is set to I_m2sin(2π·n/N-α)；

The current polarity determination program 1 is as follows: when current I₁When the voltage is less than 0A, the switching tube Q1/Q2 of the polarity switching module is controlled to be turned off, the switching tube Q3/Q4 is controlled to be turned on, and I is executed₁＝-I₁Otherwise, controlling a switch tube Q1/Q2 of the polarity switching module to be switched on, and switching tubes Q3/Q4 to be switched off; when current I₂When the voltage is less than 0A, the switching tube Q5/Q6 of the polarity switching module is controlled to be cut off, the switching tube Q7/Q8 is controlled to be switched on, and I is executed₂＝-I₂Otherwise, controlling a switch tube Q5/Q6 of the polarity switching module to be switched on, and switching tubes Q7/Q8 to be switched off;

then judging the peak time T_pIf the current I reaches the current I, if the current I does not reach the current I, the current I is executed circularly₃A closed-loop constant-current control program and a two-phase sinusoidal current control program; if the peak time T_pTo then supply the current I₃Set as a base current I_bThen the timer is started again to time the basic value time T_bAt peak time T_bIn which the current I is executed first₃Closed-loop constant-current control program, then two-phase sinusoidal current control program is executed, and then base value time T is judged_bIf the current I reaches the current I, if the current I does not reach the current I, the current I is executed circularly₁A closed-loop constant-current control program and a two-phase sinusoidal current control program; if the base value is time T_bIf so, judging whether to adjust the currentParametric or current mode, I current if no adjustment of current parameters and current mode is required₃Set as the peak current I_pThen starting a timer, and then circularly executing the control process; if the current parameter needs to be adjusted, the current parameter is reset, and then the current I is adjusted₁Current I₂And current I₃All set as 0A, the number of iterations n is set as 0, then the above-mentioned control process is executed in a loop; and if the current mode needs to be adjusted, entering a control time sequence subprogram of the corresponding current mode.

The phase shifting angle alpha exists between different phase currents of the composite current, different current combinations can be generated by controlling the phase shifting angle alpha, particularly, when the alpha is 0 degrees, the phase currents are synchronously output, when the alpha is 180 degrees, the phase currents are alternately output, namely, one phase current is in a maximum value, the other phase current is in a minimum value or a zero current state, and when the alpha is 90 degrees, three state current combinations exist: the two-phase currents are at a maximum, one phase current is at a maximum and the other phase current is at a minimum or zero current state, and both phase currents are at a minimum.

The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.