WO2022104649A1 - 一种送丝速度实时调节方法 - Google Patents

一种送丝速度实时调节方法 Download PDF

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Publication number
WO2022104649A1
WO2022104649A1 PCT/CN2020/130115 CN2020130115W WO2022104649A1 WO 2022104649 A1 WO2022104649 A1 WO 2022104649A1 CN 2020130115 W CN2020130115 W CN 2020130115W WO 2022104649 A1 WO2022104649 A1 WO 2022104649A1
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Prior art keywords
wire feeding
time
pwm
speed
waveform
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PCT/CN2020/130115
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English (en)
French (fr)
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王毅
王天雨
邵子立
秦志伟
申兆岩
刘铎
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深圳大学
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Priority to PCT/CN2020/130115 priority Critical patent/WO2022104649A1/zh
Publication of WO2022104649A1 publication Critical patent/WO2022104649A1/zh

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K9/00—Arc welding or cutting
    • B23K9/10—Other electric circuits therefor; Protective circuits; Remote controls
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K9/00—Arc welding or cutting
    • B23K9/12—Automatic feeding or moving of electrodes or work for spot or seam welding or cutting
    • B23K9/133—Means for feeding electrodes, e.g. drums, rolls, motors

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  • the present application relates to the technical field of embedded system control, in particular to a real-time adjustment method of wire feeding speed.
  • CO2 gas shielded welding is a relatively popular welding technology at present, and its application is simple and suitable for automatic welding and all-round welding. Due to its low cost and easy production of carbon dioxide gas, it is widely used in small and medium-sized enterprises. In addition, the welding seam is well formed when short-circuit transition is adopted, and high-quality welded joints without internal defects can be obtained by using the welding wire containing deoxidizer. Therefore, this welding technology has become one of the most important welding methods for ferrous materials.
  • CO2 gas protection Welding requires an additional wire feeding system for the welding process, and the stability of the wire feeding system directly determines the welding quality and welding effect.
  • the wire feeding power source using a single transformer system is attached to the welding power source.
  • the constantly changing welding voltage during the welding process will have an impact on the wire feeding machine, changing the established wire feeding speed and greatly increasing the arc breaking and explosion in the welding process. Filament and splash phenomenon.
  • the external power supply voltage of the single-transformer welding machine will change in real time with the welding voltage.
  • the embedded CPU cannot obtain a stable wire feeding speed by outputting a constant PWM pulse width. Therefore, an additional speed feedback circuit needs to be added to monitor the current wire feeding speed in real time. And adjust the PWM pulse width given by the embedded CPU to make it achieve a uniform effect.
  • the traditional speed feedback system is mostly composed of photoelectric code disc and encoder. This kind of feedback system requires modification on the wire feeding motor to obtain its real-time speed. The accuracy of the speed feedback is highly dependent on the accuracy of the photoelectric encoder used, and the cost is high and the stability needs to be improved.
  • the technical problem to be solved by the present application is to overcome the defects of high cost and poor stability in the prior art real-time adjustment method of wire feeding speed. Therefore, a real-time adjustment method of wire feeding speed is provided, which can effectively reduce the trouble of wire feeding control system of welding machine. Manufacturing costs and improved stability.
  • an embodiment of the present application provides a real-time adjustment method for a wire feeding speed, including the following steps:
  • the back electromotive force of the wire feeding motor is obtained based on the feedback circuit, and the current speed of the driving wire feeding motor is obtained;
  • the embedded CPU is used to drive the wire feeding motor in a time-sharing manner to control the state conversion and speed adjustment of the wire feeding motor;
  • the PID adjustment algorithm based on timing alignment can adjust the wire feeding speed in real time.
  • the method of driving the wire feeding motor in a time-sharing manner by an embedded CPU is used to control the state transition of the wire feeding motor and the process of adjusting the rotational speed, including:
  • the embedded CPU is internally set with 2 timers, which output state transition PWM waveform and speed control PWM waveform with different frequencies respectively.
  • the state transition PWM waveform is a fixed duty cycle of 50%, and the frequency of the speed control PWM waveform is related to the drive switch of the wire feeding motor. Frequency matching, the output to the motor drive waveform is the superposition of two pulse width waveforms of the state transition PWM waveform and the speed control PWM waveform to control the state transition of the wire feeding motor and the speed adjustment.
  • the feedback circuit includes a resistor divider circuit, a voltage follower and a low-pass RC filter circuit connected in sequence, the resistor divider circuit is connected to the wire feeding motor, and the low-pass RC filter circuit is connected to the ADC acquisition module.
  • the first half of the state transition PWM waveform outputs a low level
  • the second half of the time outputs a high level.
  • the ADC is used to collect the rotational speed feedback signal, and the high-level period Output speed control PWM.
  • the process of real-time adjustment of the wire feeding speed based on the PID adjustment algorithm of timing alignment includes:
  • time t1 is the time when the driving waveform is removed; set the delay parameter T delay to wait for the wire feeding motor to stabilize before performing ADC acquisition and start ADC.
  • the acquisition time is t2
  • the ADC acquisition time is T ADC .
  • the ADC acquisition ends, and the current rotation speed R k is calculated. Combined with the given rotation speed R target and the PWM pulse width value PWM k-1 output in the previous cycle, PID adjustment is adopted.
  • the algorithm obtains the PWM pulse width value to be output in this cycle, and outputs the calculated PWM pulse width value PWM k to the timer of the embedded CPU at time t4, and time t5 is the time t1 of the next waveform cycle, so as to continuously circulate;
  • parameters P normal , I normal and D normal are used in the PID algorithm when calculating the output PWM pulse width in the next waveform cycle;
  • embodiments of the present application provide a computer-readable storage medium, where computer instructions are stored in the computer-readable storage medium, and the computer instructions are used to cause the computer to execute the wire feeding of the first aspect of the embodiments of the present application.
  • Real-time speed adjustment method Real-time speed adjustment method.
  • an embodiment of the present application provides a processing terminal, including: a memory and a processor, wherein the memory and the processor are connected in communication with each other, the memory stores computer instructions, and the processor executes the The computer instructions are used to execute the real-time adjustment method of the wire feeding speed according to the first aspect of the embodiments of the present application.
  • the real-time adjustment method of the wire feeding speed provided by this application, according to the corresponding relationship between the motor back electromotive force and the motor speed, based on the feedback circuit to obtain the back electromotive force of the wire feeding motor, and obtain the current speed of the driving wire feeding motor; measure the back electromotive force to calculate The current motor speed has the advantages of less required components, simple circuit design, and no need to install additional speed measuring devices, which can effectively reduce the manufacturing cost of the welding machine wire feeding control system; the time-sharing driving method based on embedded CPU is combined with timing alignment based on The unique PID adjustment algorithm adjusts the wire feeding speed in real time, realizes a stable and uniform wire feeding process under the premise of saving the manufacturing cost of the welding machine, and effectively solves the problems of jitter and control lag faced by the traditional PID in the time-sharing driving mode. , which improves the stability during welding.
  • FIG. 1 is a circuit structure diagram of a wire feeding system in a digital welding machine provided in an embodiment of the present application
  • Fig. 2 is the working flow chart of a specific example of the wire feeding speed real-time adjustment method provided in the embodiment of the present application;
  • FIG. 3 is a circuit diagram of a rotational speed feedback circuit based on back electromotive force provided in an embodiment of the application;
  • FIG. 5 is a composition diagram of a specific example of a processing terminal provided by an embodiment of the present application.
  • Figure 1 shows the circuit structure diagram of the wire feeding system in the digital welding machine.
  • the external power supply is connected to the driving MOS tube of the wire feeding motor to supply power to the wire feeding motor. Due to the stable external power supply voltage of the double transformer welding machine, the embedded CPU in the control circuit can output a constant PWM pulse width to supply the wire feeding motor to generate a constant speed.
  • the external power supply voltage of the single-transformer welding machine will change in real time with the welding voltage.
  • the embedded CPU cannot obtain a stable wire feeding speed by outputting a constant PWM pulse width. Therefore, an additional speed feedback circuit needs to be added to monitor the current feeding speed in real time. wire speed and adjust the PWM pulse width given by the embedded CPU to achieve a uniform and stable effect.
  • an embodiment of the present application provides a real-time adjustment method for wire feeding speed, as shown in FIG. 2 , the method includes the following steps:
  • Step S1 According to the corresponding relationship between the back electromotive force of the motor and the rotational speed of the motor, the back electromotive force of the wire feeding motor is obtained based on the feedback circuit, and the current rotational speed of the driving wire feeding motor is obtained.
  • the feedback circuit includes a resistor divider circuit, a voltage follower and a low-pass RC filter circuit which are connected in sequence.
  • the resistor divider circuit is connected to the wire feeding motor, and the low-pass RC filter circuit is connected to the ADC.
  • the acquisition module is connected. Since the back EMF is proportional to the current speed of the motor, the current motor speed can be calculated by measuring the back EMF. For a permanent magnet DC motor, the relationship between the back EMF at both ends of the motor and the speed is:
  • ES is the back electromotive force
  • C e is a constant
  • ⁇ b is the permanent magnet magnetic flux
  • n is the rotational speed
  • Step S2 adopting the embedded CPU to drive the wire feeding motor in a time-sharing manner to control the state transition of the wire feeding motor and the adjustment of the rotational speed.
  • the embedded CPU in step S2 drives the wire feeding motor in a time-sharing manner to control the state transition and rotational speed adjustment of the wire feeding motor.
  • the embedded CPU of the embodiment of the present application is internally set with two timers, which respectively output a state transition PWM waveform and a rotational speed control PWM waveform with different frequencies.
  • the state transition PWM waveform is a fixed duty cycle of 50%, and the rotational speed control PWM waveform
  • the frequency of the wire feeding motor matches the switching frequency of the wire feeding motor, and the output to the motor driving waveform is the superposition of the two pulse width waveforms of the state conversion PWM waveform and the speed control PWM waveform to control the wire feeding motor state conversion and speed adjustment.
  • the first half of the state transition PWM waveform outputs a low level
  • the second half of the time outputs a high level.
  • the ADC is used to collect the speed feedback signal
  • the high-level period outputs the speed control PWM.
  • Step S3 the wire feeding speed is adjusted in real time based on the PID adjustment algorithm of timing alignment.
  • PID algorithm is the abbreviation of proportional, integral and differential control. It has become one of the main technologies of industrial control because of its simple structure, good stability, reliable operation and convenient adjustment. When the structure and parameters of the controlled object cannot be fully grasped, or an accurate mathematical model cannot be obtained, other techniques of control theory are difficult to use. The structure and parameters of the system controller must be determined by experience and on-site debugging, and PID control technology is applied. most convenient.
  • the embodiment of the present application proposes a PID adjustment algorithm based on timing alignment, which adopts different PID parameters for different control delays in the time-sharing driving environment, which effectively solves the jitter and jitter that traditional PIDs face in the time-sharing driving mode. Control lag, etc.
  • Fig. 4 is a timing logic diagram of time-sharing driving in the embedded CPU.
  • the current waveform cycle is the kth cycle
  • the time t1 is the time when the driving waveform is removed.
  • a delay parameter T delay is introduced to wait for wire feeding.
  • the ADC acquisition is performed after the motor state is stable; the time to start the ADC acquisition is t2, and the ADC acquisition time is T ADC .
  • This parameter can be determined after configuring the ADC module in the embedded CPU.
  • PWM k PIDcalculate(PWM k-1 ,R k ,R target ),
  • PWM(k) represents the current voltage
  • err(k) represents the error between the current speed at time k and the given speed
  • err(k-1) represents the error between the current speed at time k-1 and the given speed
  • P normal , I normal and D normal are all control parameters in the PID algorithm.
  • Time t5 is the time t1 of the next waveform cycle, and the cycle continues.
  • the time delay T PID of running the PID adjustment algorithm is not Not fixed. Since the frequency of the PWM1 waveform cannot be too low, that is, the length of the PWM1 waveform high/low level output time T deadline cannot be too short, otherwise the inertia of the wire feeding motor is not enough to keep it rotating at a stable and uniform speed, so it may appear that T deadline ⁇ T delay +T ADC +T PID ⁇ 2*T deadline . In this case, when the time t4 comes, the required PWM pulse width value PWM k calculation cannot be completed (the PID algorithm has not been executed), so only the PWM pulse width value PWM k-1 of the previous waveform cycle can be output.
  • the embodiment of the present application proposes a PID adjustment algorithm based on timing alignment to adjust the wire feeding speed in real time.
  • the basic principle is to simulate the delayed control signal by observing the change of the error. possible effects.
  • the specific adjustment can be divided into two situations:
  • the new PID adjustment parameter P delay is applied.
  • I delay and D delay the values of the three are determined according to the error between the given speed R target speed and the actual speed; considering the possible influence of the PWM k that has no effect, the PID parameters required for calculating PWM k+1 After adjustment, the new PID adjustment parameters P delay , I delay and D delay satisfy the following relationship:
  • the embodiment of the present application records the waveform period in which the ADC collects each time and the waveform period in which the PID algorithm is used to calculate the PWM pulse width value by setting the parameters ADC version and PWM version respectively, and the acquisition of the ADC is completed each time, then The ADC version is incremented by 1; each time the calculation of the PWM pulse width is completed, the PWM version is incremented by 1.
  • time t4 it is determined whether the ADC version and the PWM version are equal to determine the PWM pulse width calculated and output in the next waveform cycle. time parameters.
  • the parameters P delay , I delay and D delay are used in the PID algorithm during the PWM pulse width.
  • time-sharing driving method based on an embedded CPU and the PID adjustment wire feeding speed algorithm based on timing alignment proposed in the embodiment of the present application are further described in detail by using algorithm pseudocode:
  • the device may include a processor 51 and a memory 52 , where the processor 51 and the memory 52 may be connected through a bus or in other ways.
  • FIG. 5 takes the connection through a bus as an example .
  • the processor 51 can be a central processing unit (Central Processing Unit, CPU), and can also be other general-purpose processors, digital signal processors (Digital Signal Processors, DSPs), application specific integrated circuits (Application Specific Integrated Circuits, ASICs), field-available processors.
  • Programmable gate array Field-Programmable Gate Array, FPGA or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components and other chips, or a combination of the above types of chips.
  • the memory 52 can be used to store non-transitory software programs, non-transitory computer-executable programs and modules, such as corresponding program instructions/modules in the embodiments of the present application.
  • the processor 51 executes various functional applications and data processing of the processor by running the non-transitory software programs, instructions and modules stored in the memory 52, that is, the real-time adjustment method of the wire feeding speed in the above method embodiment 1 is realized.
  • the memory 52 may include a storage program area and a storage data area, wherein the storage program area may store an operating system and an application program required by at least one function; the storage data area may store data created by the processor 51 and the like. Additionally, memory 52 may include high-speed random access memory, and may also include non-transitory memory, such as at least one magnetic disk storage device, flash memory device, or other non-transitory solid state storage device. In some embodiments, memory 52 may optionally include memory located remotely from processor 51 , which may be connected to processor 51 via a network. Examples of such networks include, but are not limited to, the Internet, intranets, intranets, mobile communication networks, and combinations thereof.
  • One or more modules are stored in the memory 52, and when executed by the processor 51, execute the real-time adjustment method of the wire feeding speed in Embodiment 1.
  • the storage medium may be a magnetic disk, an optical disk, a read-only memory (Read-Only Memory, ROM), a random access memory (Random Access Memory, RAM), a flash memory (Flash Memory), a hard disk (Hard Disk Drive) , abbreviation: HDD) or solid-state drive (Solid-State Drive, SSD), etc.; the storage medium may also include a combination of the above-mentioned types of memories.

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Abstract

本申请公开了一种送丝速度实时调节方法，包括：根据电机反电动势和电机转速的对应关系，基于反馈电路获取送丝电机的反电动势，获取驱动送丝电机当前的转速；采用嵌入式CPU分时驱动送丝电机的方式，控制送丝电机状态转换以及转速调节；基于时序对齐的PID调节算法对送丝速度进行实时调节。本申请基于反馈电路获取送丝电机的反电动势即可计算出当前电机转速，其具有所需元器件少，电路设计简单，无需额外安装测速装置等优点，可以有效降低焊机送丝控制系统的制造成本；基于嵌入式CPU的分时驱动方式结合基于时序对齐的PID调节算法对送丝速度进行实时调节，在节省焊机制造成本的前提下实现了稳定匀速的送丝过程，提高了焊接过程中的稳定性。

Description

一种送丝速度实时调节方法 技术领域
本申请涉及嵌入式系统控制技术领域，具体涉及一种送丝速度实时调节方法。
背景技术
CO2气体保护焊是目前较为流行的一种焊接技术，其应用方面操作简单，适合自动焊和全方位焊接。由于其成本低，二氧化碳气体易生产，广泛应用于各大中小企业。加之其采用短路过渡时焊缝成形良好，使用含脱氧剂的焊丝即可获得无内部缺陷的高质量焊接接头，因此这种焊接技术目前已成为黑色金属材料最重要焊接方法之一，CO2气体保护焊需要有额外的送丝系统用于焊接过程，且送丝系统的稳定性直接决定了焊接质量以及焊接效果。
现有技术采用单变压器系统的送丝电源附属于焊接电源，在焊接过程中不断变化的焊接电压将对送丝机产生影响，改变既定好的送丝速度，大大增加焊接过程的断弧、爆丝及飞溅现象。单变压器焊机的外部电源电压将跟随焊接电压实时变化，嵌入式CPU无法通过输出恒定的PWM脉宽来得到稳定的送丝速度，因此需要加入额外的转速反馈电路来实时监测当前的送丝速度并调整嵌入式CPU给出的PWM脉宽，使其达到匀速的效 果。传统的转速反馈系统多采用光电码盘及编码器构成，此种反馈系统要求在送丝电机上进行改造，从而获取其实时转速。转速反馈的精度高度依赖于采用的光电码盘的精度，成本高且稳定性有待提高。
发明内容
因此，本申请要解决的技术问题在于克服现有技术中送丝速度实时调节方法成本高且稳定差的缺陷，因此提供一种送丝速度实时调节方法，可以有效降低焊机送丝控制系统的制造成本，提高稳定性。
为达到上述目的，本申请提供如下技术方案：
第一方面，本申请实施例提供一种送丝速度实时调节方法，包括如下步骤：
根据电机反电动势和电机转速的对应关系，基于反馈电路获取送丝电机的反电动势，获取驱动送丝电机当前的转速；
采用嵌入式CPU分时驱动送丝电机的方式，控制送丝电机状态转换以及转速调节；
基于时序对齐的PID调节算法对送丝速度进行实时调节。
在一实施例中，采用嵌入式CPU分时驱动送丝电机的方式，控制送丝电机状态转换以及转速调节的过程，包括：
嵌入式CPU内部设置2个定时器，分别输出频率不同的状态转换PWM波形和转速控制PWM波形，状态转换PWM波形为占空比固定为50％，转速控 制PWM波形的频率与送丝电机驱动开关频率匹配，输出至电机驱动波形为状态转换PWM波形和转速控制PWM波形的两个脉宽波形的叠加，来控制送丝电机状态转换以及转速调节。
在一实施例中，反馈电路包括依次连接的电阻分压电路、电压跟随器以及低通RC滤波电路，电阻分压电路与送丝电机连接，低通RC滤波电路与ADC采集模块连接。
在一实施例中，在一个波形周期内，状态转换PWM波形中前一半时间输出低电平，后一半时间输出高电平，低电平时间段利用ADC采集转速反馈信号，高电平时间段输出转速控制PWM。
在一实施例中，基于时序对齐的PID调节算法对送丝速度进行实时调节的过程，包括：
设当前波形周期为第k个周期，在分时驱动的时序逻辑图中，t1时刻为驱动波形撤除时刻；设置延迟参数T delay用于等待送丝电机状态稳定后再进行ADC的采集，开始ADC采集的时刻为t2，ADC采集耗时T ADC，在t3时刻ADC采集结束，开始计算当前转速R k，结合给定转速R target以及上周期输出的PWM脉宽数值PWM k-1，采用PID调节算法得出本周期需输出的PWM脉宽数值，t4时刻将算得的PWM脉宽数值PWM k输出至嵌入式CPU的定时器，t5时刻即下一波形周期的t1时刻，以此不断循环；
如果计算第k个周期的PWM k的时长T PID未超出状态转换PWM波形中低电平的输出截止时间T deadline，得出PWM k的时刻未超过t4时刻，此时 保持PID算法中的参数P normal，I normal以及D normal不改变，继续用于PWM k+1的计算；
如果计算第k个周期的PWM k的时长T PID超出状态转换PWM波形中低电平的输出截止时间T deadline，得出PWM k的时刻超过了t4时刻，应用新的PID调节参数P delay，I delay以及D delay，三者的值根据给定转速R target转速与实际转速的误差确定；
设置参数ADC version、PWM version分别记录每次ADC采集所处的波形周期以及每次使用PID算法计算PWM脉宽数值时所处的波形周期，每次进行完ADC的采集，则ADC version自增1；每次进行完PWM脉宽数值的计算，则PWM version自增1，当t4时刻来到，判断ADC version与PWM version是否相等来确定在下一波形周期计算输出的PWM脉宽时的参数。
在一实施例中，当ADC version＝PWM version时，下一波形周期计算输出的PWM脉宽时PID算法中采用参数P normal，I normal以及D normal；
当ADC version＝PWM version+1时，下一波形周期计算输出的PWM脉宽时PID算法中采用参数P delay，I delay以及D delay。
第二方面，本申请实施例提供一种计算机可读存储介质，所述计算机可读存储介质存储有计算机指令，所述计算机指令用于使所述计算机执行本申请实施例第一方面的送丝速度实时调节方法。
第三方面，本申请实施例提供一种处理终端，包括：存储器和处理器， 所述存储器和所述处理器之间互相通信连接，所述存储器存储有计算机指令，所述处理器通过执行所述计算机指令，从而执行本申请实施例第一方面的送丝速度实时调节方法。
本申请技术方案，具有如下优点：
本申请提供了的送丝速度实时调节方法，根据电机反电动势和电机转速的对应关系，基于反馈电路获取送丝电机的反电动势，获取驱动送丝电机当前的转速；测量反电动势即可计算出当前电机转速，其具有所需元器件少，电路设计简单，无需额外安装测速装置等优点，可以有效降低焊机送丝控制系统的制造成本；基于嵌入式CPU的分时驱动方式结合基于时序对齐的PID调节算法对送丝速度进行实时调节，在节省焊机制造成本的前提下实现了稳定匀速的送丝过程，有效解决了在分时驱动的方式下传统PID面临的抖动和控制滞后等问题，提高了焊接过程中的稳定性。
附图说明
为了更清楚地说明本申请具体实施方式或现有技术中的技术方案，下面将对具体实施方式或现有技术描述中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图是本申请的一些实施方式，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他的附图。
图1本申请实施例中提供的数字化焊机中送丝系统的电路结构图；
图2本申请实施例中提供的送丝速度实时调节方法的一个具体示例 的工作流程图；
图3为本申请实施例中提供的基于反电动势的转速反馈电路图；
图4本申请实施例中提供的分时驱动在嵌入式CPU内的时序逻辑图；
图5为本申请实施例提供的处理终端一个具体示例的组成图。
具体实施方式
下面将结合附图对本申请的技术方案进行清楚、完整地描述，显然，所描述的实施例是本申请一部分实施例，而不是全部的实施例。基于本申请中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本申请保护的范围。
此外，下面所描述的本申请不同实施方式中所涉及的技术特征只要彼此之间未构成冲突就可以相互结合。
实施例1
图1展示了数字化焊机中送丝系统的电路结构图，外部供电电源接入送丝电机的驱动MOS管，用于向送丝电机供电。双变压器焊机由于拥有稳定的外部电源电压，其控制电路中的嵌入式CPU可以输出恒定的PWM脉宽来供给送丝电机，使其产生恒定的转速。然而，单变压器焊机的外部电源电压将跟随焊接电压实时变化，嵌入式CPU无法通过输出恒定的PWM脉宽来得到稳定的送丝速度，因此需要加入额外的转速反馈电路来实时监测当前的送丝速度并调整嵌入式CPU给出的PWM脉宽，使其达 到匀速稳定的效果。
基于此，本申请实施例提供一种送丝速度实时调节方法，如图2所示，该方法包括如下步骤：
步骤S1：根据电机反电动势和电机转速的对应关系，基于反馈电路获取送丝电机的反电动势，获取驱动送丝电机当前的转速。
在本申请实施例中，如图3所示反馈电路包括依次连接的电阻分压电路、电压跟随器以及低通RC滤波电路，电阻分压电路与送丝电机连接，低通RC滤波电路与ADC采集模块连接，由于反电动势正比于电机的当前转速，测量反电动势即可计算出当前电机转速，对于永磁直流电机来说，电机两端的反电动势与转速之间的关系式为：
E S＝C eφ bn，
其中，E S为反电动势，C e为常数，φ b为永磁磁通，n为转速。
步骤S2：采用嵌入式CPU分时驱动送丝电机的方式，控制送丝电机状态转换以及转速调节。
虽然基于反电动势的转速反馈电路无需额外改造送丝电机，但为测得反电动势，必须通过分时技术使电机处于电动机和发电机两种不同的状态。因此本申请实施例采用步骤S2中的嵌入式CPU分时驱动送丝电机的方式，控制送丝电机状态转换以及转速调节。具体的，本申请实施例的嵌入式CPU内部设置2个定时器，分别输出频率不同的状态转换PWM波形和转速控制 PWM波形，状态转换PWM波形为占空比固定为50％，转速控制PWM波形的频率与送丝电机驱动开关频率匹配，输出至电机驱动波形为状态转换PWM波形和转速控制PWM波形的两个脉宽波形的叠加，来控制送丝电机状态转换以及转速调节。在一个波形周期内，状态转换PWM波形中前一半时间输出低电平，后一半时间输出高电平，低电平时间段利用ADC采集转速反馈信号，高电平时间段输出转速控制PWM。
步骤S3：基于时序对齐的PID调节算法对送丝速度进行实时调节。
传统的数字化控制多采用PID调节算法实现加入转速反馈后的送丝速度实时调节。PID算法是比例、积分、微分控制的缩写，、它以其结构简单、稳定性好、工作可靠、调整方便而成为工业控制的主要技术之一。当被控对象的结构和参数不能完全掌握，或得不到精确的数学模型时，控制理论的其它技术难以采用，系统控制器的结构和参数必须依靠经验和现场调试来确定，应用PID控制技术最为方便。
应用本申请实施例提出的基于嵌入式CPU的分时驱动方法后，传统的PID调节未考虑在分时驱动的环境下面临的控制延迟问题。因此本申请实施例提出了一种基于时序对齐的PID调节算法，针对分时驱动环境中不同的控制时延采用不同的PID参数，有效解决了在分时驱动的方式下传统PID面临的抖动和控制滞后等问题。
图4为分时驱动在嵌入式CPU内的时序逻辑图，设当前波形周期为第k个周期，t1时刻为驱动波形撤除时刻，本实施例引入了一延迟参数T delay，用 于等待送丝电机状态稳定后再进行ADC的采集；开始ADC采集的时刻为t2，ADC采集耗时T ADC，此参数在配置好嵌入式CPU中的ADC模块后即可确定。在t3时刻ADC采集结束，开始计算当前转速R k，之后结合给定转速R target以及上周期输出的PWM脉宽数值PWM k-1，程序将运行PID算法得出本周期需输出的PWM脉宽数值：
PWM k＝PIDcalculate(PWM k-1,R k,R target)，
其中，PID算法具体的公式为:
Figure PCTCN2020130115-appb-000001
PWM(k)表示当前电压，err(k)表示k时刻的当前转速与给定转速之间的误差，err(k-1)表示k-1时刻的当前转速与给定转速之间的误差，P normal，I normal以及D normal均为PID算法中的控制参数。
t4时刻程序将算得的PWM脉宽数值PWM k输出至嵌入式CPU的定时器。t5时刻即下一波形周期的t1时刻，以此不断循环。
在实际应用过程中，由于嵌入式CPU不仅仅处理单一送丝电机调速任务，还有其他任务(例如通信、存储、采集等其他信号)需要处理，因此运行PID调节算法的时延T PID并不固定。由于PWM1波形的频率不能太低，即PWM1波形高/低电平输出时间T deadline的长度不能太短，否则送丝电机的惯性不足以让其保持稳定匀速转动，因此可能出现T deadline<T delay+T ADC+T PID<2*T deadline的情况。此种情况下，当t4时刻到来时无法完成 所需的PWM脉宽数值PWM k计算(PID算法未执行完毕)，因此只能输出上一波形周期的PWM脉宽数值PWM k-1。
当t5时刻即下一波形周期的t1时刻到来之前，PID调节算法一定会执行完毕得出所需的PWM k，但由于在t4时刻已经将PWM k-1输出至嵌入式CPU的定时器，此次PWM控制值PWM k将无法起到控制送丝电机速度的效果。此时来到第k+1个波形周期，采集得到的当前转速R k+1实际上是应用了前两个波形周期PWM k-1后的效果(而非期望的前一个波形周期PWM k所产生的效果)，因此将产生控制延迟。
针对因T PID不固定所可能导致的控制延迟问题，本申请实施例提出了基于时序对齐的PID调节算法对送丝速度进行实时调节，其基本原理是通过观察误差的改变模拟被延迟的控制信号可能带来的效果。具体调节可分为两种情况：
1、如果计算第k个周期的PWM k的时长T PID未超出状态转换PWM波形中低电平的输出截止时间T deadline，得出PWM k的时刻未超过t4时刻，此时保持PID算法中的参数P normal，I normal以及D normal不改变，继续用于PWM k+1的计算；
2、如果计算第k个周期的PWM k的时长T PID超出状态转换PWM波形中低电平的输出截止时间T deadline，得出PWM k的时刻超过了t4时刻，应用新的PID调节参数P delay，I delay以及D delay，三者的值根据给定转速R target转速与实际转速的误差确定；考虑未产生效果的PWM k可能造成的影响，对 用于计算PWM k+1所需的PID参数进行调整,新的PID调节参数P delay，I delay以及D delay满足以下关系式：
Figure PCTCN2020130115-appb-000002
Figure PCTCN2020130115-appb-000003
Figure PCTCN2020130115-appb-000004
本申请实施例通过设置参数ADC version、PWM version分别记录每次ADC采集所处的波形周期以及每次使用PID算法计算PWM脉宽数值时所处的波形周期，每次进行完ADC的采集，则ADC version自增1；每次进行完PWM脉宽数值的计算，则PWM version自增1，当t4时刻来到，判断ADC version与PWM version是否相等来确定在下一波形周期计算输出的PWM脉宽时的参数。
当ADC version＝PWM version时，下一波形周期计算输出的PWM脉宽时PID算法中采用参数P normal，I normal以及D normal；当ADC version＝PWM version+1时，下一波形周期计算输出的PWM脉宽时PID算法中采用参数P delay，I delay以及D delay。
在一具体实施例中，利用算法伪代码对本申请实施例提出的基于嵌入式CPU的分时驱动方法以及基于时序对齐的PID调节送丝速度算法做进一步的详细说明：
Figure PCTCN2020130115-appb-000005
Figure PCTCN2020130115-appb-000006
Figure PCTCN2020130115-appb-000007
Figure PCTCN2020130115-appb-000008
实施例2
本申请实施例提供一种处理终端，如图5所示，该设备可以包括处理器51和存储器52，其中处理器51和存储器52可以通过总线或者其他方式连接，图5以通过总线连接为例。
处理器51可以为中央处理器(Central Processing Unit，CPU)，还可以为其他通用处理器、数字信号处理器(Digital Signal Processor，DSP)、专用集成电路(Application Specific Integrated Circuit，ASIC)、现场可编程门阵列(Field-Programmable Gate Array，FPGA)或者其他可编程逻辑器件、分立门或者晶体管逻辑器件、分立硬件组件等芯片，或者上述各类芯片的组合。
存储器52作为一种非暂态计算机可读存储介质，可用于存储非暂态软件程序、非暂态计算机可执行程序以及模块，如本申请实施例中的对应的程序指令/模块。处理器51通过运行存储在存储器52中的非暂态软件程序、指令以及模块，从而执行处理器的各种功能应用以及数据处理，即实现上述方法实施例1中的送丝速度实时调节方法。
存储器52可以包括存储程序区和存储数据区，其中，存储程序区可存储操作系统、至少一个功能所需要的应用程序；存储数据区可存储处理器51所创建的数据等。此外，存储器52可以包括高速随机存取存储器，还可以包括非暂态存储器，例如至少一个磁盘存储器件、闪存器件、或其他非暂态固态存储器件。在一些实施例中，存储器52可选包括相对于处理器51远程设置的存储器，这些远程存储器可以通过网络连接至处理器51。上述网络的实例包括但不限于互联网、企业内部网、企业内网、移动通信网及其组合。
一个或者多个模块存储在存储器52中，当被处理器51执行时，执行实施例1中的送丝速度实时调节方法。
上述处理终端具体细节可以对应参阅实施例1中对应的相关描述和效果进行理解，此处不再赘述。
本领域技术人员可以理解，实现上述实施例方法中的全部或部分流程，是可以通过计算机程序来指令相关的硬件来完成的程序可存储于一计算机可读取存储介质中，该程序在执行时，可包括如上述各方法的实施例的流程。其中，存储介质可为磁碟、光盘、只读存储记忆体(Read-Only Memory，ROM)、随机存储记忆体(Random Access Memory，RAM)、快闪存储器(Flash Memory)、硬盘(Hard Disk Drive，缩写：HDD)或固态硬盘(Solid-State Drive，SSD)等；存储介质还可以包括上述种类的存储器的组合。
显然，上述实施例仅仅是为清楚地说明所作的举例，而并非对实施方式的限定。对于所属领域的普通技术人员来说，在上述说明的基础上还可以做出其它不同形式的变化或变动。这里无需也无法对所有的实施方式予以穷举。而由此所引申出的显而易见的变化或变动仍处于本发明创造的保护范围之中。

Claims (9)

  1. 一种送丝速度实时调节方法，其特征在于，包括如下步骤：
    根据电机反电动势和电机转速的对应关系，基于反馈电路获取送丝电机的反电动势，获取驱动送丝电机当前的转速；
    采用嵌入式CPU分时驱动送丝电机的方式，控制送丝电机状态转换以及转速调节；
    基于时序对齐的PID调节算法对送丝速度进行实时调节。
  2. 根据权利要求1所述的送丝速度实时调节方法，其特征在于，采用嵌入式CPU分时驱动送丝电机的方式，控制送丝电机状态转换以及转速调节的过程，包括：
    嵌入式CPU内部设置2个定时器，分别输出频率不同的状态转换PWM波形和转速控制PWM波形，状态转换PWM波形为占空比固定为50％，转速控制PWM波形的频率与送丝电机驱动开关频率匹配，输出至电机驱动波形为状态转换PWM波形和转速控制PWM波形的两个脉宽波形的叠加，来控制送丝电机状态转换以及转速调节。
  3. 根据权利要求1或2的送丝速度实时调节方法，其特征在于，反馈电路包括依次连接的电阻分压电路、电压跟随器以及低通RC滤波电路，电阻分压电路与送丝电机连接，低通RC滤波电路与ADC采集模块连接。
  4. 根据权利要求3的送丝速度实时调节方法，其特征在于，在一个波形 周期内，状态转换PWM波形中前一半时间输出低电平，后一半时间输出高电平，低电平时间段利用ADC采集转速反馈信号，高电平时间段输出转速控制PWM。
  5. 根据权利要求4所述的送丝速度实时调节方法，其特征在于，基于时序对齐的PID调节算法对送丝速度进行实时调节的过程，包括：
    设当前波形周期为第k个周期，在分时驱动的时序逻辑图中，t1时刻为驱动波形撤除时刻；设置延迟参数T delay用于等待送丝电机状态稳定后再进行ADC的采集，开始ADC采集的时刻为t2，ADC采集耗时T ADC，在t3时刻ADC采集结束，开始计算当前转速R k，结合给定转速R target以及上周期输出的PWM脉宽数值PWM k-1，采用PID调节算法得出本周期需输出的PWM脉宽数值，t4时刻将算得的PWM脉宽数值PWM k输出至嵌入式CPU的定时器，t5时刻即下一波形周期的t1时刻，以此不断循环；
    如果计算第k个周期的PWM k的时长T PID未超出状态转换PWM波形中低电平的输出截止时间T deadline，得出PWM k的时刻未超过t4时刻，此时保持PID算法中的参数P normal，I normal以及D normal不改变，继续用于PWM k+1的计算；
    如果计算第k个周期的PWM k的时长T PID超出状态转换PWM波形中低电平的输出截止时间T deadline，得出PWM k的时刻超过了t4时刻，应用新的PID调节参数P delay，I delay以及D delay，三者的值根据给定转速R target转速与实际转速的误差确定；
    设置参数ADC version、PWM version分别记录每次ADC采集所处的波形周期以及每次使用PID算法计算PWM脉宽数值时所处的波形周期，每次进行完ADC的采集，则ADC version自增1；每次进行完PWM脉宽数值的计算，则PWM version自增1，当t4时刻来到，判断ADC version与PWM version是否相等来确定在下一波形周期计算输出的PWM脉宽时的参数。
  6. 根据权利要求5所述的送丝速度实时调节方法，其特征在于，当ADC version＝PWM version时，下一波形周期计算输出的PWM脉宽时PID算法中采用参数P normal，I normal以及D normal；当ADC version＝PWM version+1时，下一波形周期计算输出的PWM脉宽时PID算法中采用参数P delay，I delay以及D delay。
  7. 根据权利要求5所述的送丝速度实时调节方法，其特征在于，新的PID调节参数P delay，I delay以及D delay满足以下关系式：
    Figure PCTCN2020130115-appb-100001
    Figure PCTCN2020130115-appb-100002
    Figure PCTCN2020130115-appb-100003
  8. 一种计算机可读存储介质，其特征在于，所述计算机可读存储介质存储有计算机指令，所述计算机指令用于使所述计算机执行如权利要求1-7任一项所述的送丝速度实时调节方法。
  9. 一种处理终端，其特征在于，包括：存储器和处理器，所述存储器和所述处理器之间互相通信连接，所述存储器存储有计算机指令，所述处理 器通过执行所述计算机指令，从而执行如权利要求1-7任一项所述的送丝速度实时调节方法。
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