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CN-122026277-A - STO circuit system based on high security level is cut off to converter moment of torsion

CN122026277ACN 122026277 ACN122026277 ACN 122026277ACN-122026277-A

Abstract

The invention relates to the technical field of frequency converter safety control, and discloses a STO circuit system with high safety level based on frequency converter torque turn-off, which comprises a STO expansion board and a control board which are electrically connected with each other; the STO expansion board is provided with two paths of independent pulse generating modules, a driving module, a receiving module, a pulse detecting module, a level converting module and an isolating module which are arranged in an electric signal isolating layer, and the STO expansion board transmits a double-channel differential characteristic pulse signal through initiative, and sequentially passes through pulse detecting and level converting processes after passing back through an external safety loop, and transmits the signal to a control board. According to the invention, through active pulse excitation-readback verification, a frequency and duty ratio differential design of a dual-channel differential characteristic pulse is matched, and meanwhile, an isolation design, cross mutual detection, graded driving and MCU closed loop verification four-layer safety protection mechanism is constructed, and the safety grade is improved to SIL3/PLe by combining power supply control and set-enabling graded driving logic.

Inventors

  • MA QIANG
  • YU GONGJUN
  • SHEN TAO

Assignees

  • 万维电气(惠州)有限公司

Dates

Publication Date
20260512
Application Date
20260206

Claims (10)

  1. 1. STO circuit system based on high security level of torque turn-off of frequency converter, characterized by, include STO expansion board and control panel that interconnect electricity; The STO expansion board is provided with two paths of independent pulse generating modules, a driving module, a receiving module, a pulse detecting module, a level converting module and an isolating module which are arranged in an electric signal isolating layer, and the STO expansion board transmits a double-channel differential characteristic pulse signal to a control board through active transmission, pulse detection and level converting processing after passing back through an external safety loop in sequence; The control board is a logic control layer built-in MCU core unit, a double independent power supply module and two paths of PWM driving modules, and through an isolation design, cross mutual detection, grading driving and MCU closed loop verification four-layer safety protection mechanism, torque output control of the IGBT power unit of the frequency converter is achieved, and three states of loop conduction, normal turn-off and line breakage are distinguished so as to meet SIL3/PLe high safety level requirements.
  2. 2. The STO circuit system with high safety level based on torque turn-off of the frequency converter according to claim 1, wherein the differential form of the two-channel differential characteristic pulse signal at least comprises one of frequency, duty cycle, phase and modulation mode, wherein the first channel pulse generator outputs a pulse signal with frequency f 1 duty cycle of 90%, the second channel pulse generator outputs a pulse signal with frequency f 2 duty cycle of 70%, and f 1 ≠f 2 ; The pulse detection module comprises a first pulse detection module and a second pulse detection module, the first pulse detection module is corresponding to the matched double-channel pulse characteristics, the first pulse detection module is only responsive to f 1 frequency pulses, the second pulse detection module is only responsive to f 2 frequency pulses, when the pulse signals with the matched characteristics are detected, when the output double-channel differential pulse signals are abnormal, the output double-channel low level is output, and misjudgment caused by channel crosstalk is avoided.
  3. 3. The STO circuit system of claim 2, wherein the isolation module includes at least 5 isolation devices respectively disposed at the pulse transmitting end, the detecting end, the transmission link and the feedback circuit, and the isolation devices are selected from one of photoelectric isolation, magnetic isolation and capacitive isolation.
  4. 4. The STO circuit system based on the high safety level of the torque turn-off of the frequency converter as claimed in claim 3, wherein in the four-layer safety protection mechanism, the cross-checking is realized by the characteristic check and the state comparison of the two-channel pulse signals, and when the single-channel pulse signals are abnormal, the system immediately judges the fault and cuts off the torque output; the hierarchical driving adopts a timing control logic of power supply control and enabling setting, a double independent power supply module of the control panel supplies power to the two paths of PWM driving modules respectively, the enabling end of the power supply is controlled by STOA and STOB signals output by the STO expansion board, the enabling end of the PWM driving module is correspondingly connected with the STOA and STOB signals respectively, and the PWM driving module can output driving signals only when the power supply is normal and the setting of the enabling end is effective.
  5. 5. The STO circuit system with high safety level based on torque turn-off of a frequency converter as claimed in claim 4, wherein the pulse generating module adopts a SE555 chip to form a pulse generating circuit, and the frequency, the duty cycle and the phase are adjustable; The pulse detection module is formed by connecting two 74HC123 chips in series and is used for converting single pulse into differential pair pulse output; the level conversion module adopts a differential-to-single-ended chip 74HC32, shapes the double-path differential pulse signals output by the pulse detection module into stable high-low fixed level signals STOA and STOB, adapts to the PWM enabling of the control board and the enabling control signal requirement of the driving chip, and ensures the stability and compatibility in the signal transmission process.
  6. 6. The STO circuit system with high safety level based on torque turn-off of a frequency converter as claimed in claim 5, wherein the MCU core unit of the control board adopts a 32-bit microcontroller XE164HN, the input end of the MCU core unit receives STOA and STOB signals, and a built-in pulse characteristic verification algorithm performs real-time comparison verification on the frequency and level states of the two signals; The double independent power modules realize accurate start-stop control through the on and off of the PMOS, the first power module supplies power for the second PWM driving module, the second power module supplies power for the first PWM driving module, the output ends of the two paths of PWM driving modules are connected in series and then connected to the IGBT power unit of the frequency converter, and the IGBT power unit can output torque only when the two paths of driving circuits are in an effective working state, so that redundant driving protection is formed.
  7. 7. The high-safety-level STO circuitry based on converter torque shutdown of claim 6, wherein the STO expansion board further comprises a feedback circuit and an indicator light module; The feedback circuit consists of a two-stage 74HC14 shaping driving circuit and a photoelectric isolation circuit and is used for transmitting a fault code generated by the MCU to a human-computer interface of the frequency converter and a remote monitoring system; the three-color indicator lamp or the independent indicator lamp is adopted by the indicator lamp module, and the three states of normally-on, off and flashing correspond to the three states of loop conduction, normally-off and line break respectively, so that the fault code supports the access of the factory MES system to realize remote state monitoring and early warning, the equipment maintenance efficiency is improved, and the risk of unplanned shutdown is reduced.
  8. 8. The converter torque shutdown high security level based STO circuitry of claim 7, wherein an alternative to the differential feature of the dual channel pulse signal comprises: The frequency is unchanged, the duty ratio of the first channel is 50%, the duty ratio of the second channel is 30%, and the detection module completes channel identification through checking the duty ratio threshold; the frequency and the duty ratio are unchanged, the pulse phase difference of the two channels is 90 degrees, and the detection module realizes the two-channel signal distinction through phase discrimination; Different modulation modes are adopted, the first channel is a common square wave pulse, the second channel is an FSK frequency shift keying pulse, and the detection module completes signal identification through a demodulation mode, so that the equivalent channel crosstalk prevention effect is realized.
  9. 9. The STO circuit system with high safety level based on the torque turn-off of the frequency converter as claimed in claim 8, wherein when the isolation module adopts a magnetic isolation device, a magnetic coupling element is selected, and the signal transmission and the electrical isolation are realized through an electromagnetic induction principle; when the isolation module adopts a capacitance isolation device, the high-frequency pulse transmission scene is adapted, the signal transmission bandwidth is higher than that of the photoelectric isolation device, and the isolation transmission requirement of a pulse signal with higher frequency can be met.
  10. 10. The converter torque based high safety level STO circuitry of claim 9, wherein an alternative to the step-driven timing control logic includes: setting the enabling end of the PWM driving module, controlling the corresponding power module to supply power, and realizing hierarchical driving through time sequence adjustment to achieve the same safety control effect as the original scheme; The bypass cutting mode of the driving signal is adopted to replace power supply control, and the on-off of the bypass switch is controlled by the MCU, so that the effective output or cutting of the PWM driving signal is realized.

Description

STO circuit system based on high security level is cut off to converter moment of torsion Technical Field The invention relates to the technical field of safety control of frequency converters, in particular to a STO circuit system with high safety level based on torque turn-off of a frequency converter. Background Under the dual driving of industrial automation upgrading and 'double carbon' strategy, the frequency converter is used as core equipment for motor speed regulation and energy saving control, the industrial scale is continuously expanded, the development of 800 hundred million yuan is expected to be broken through in 2025 years, the intelligent, green and high-safety directions are gradually developed, along with the continuous deepening of the application of the frequency converter in the key fields of metallurgy, chemical industry, intelligent manufacturing and the like, the rapid and reliable cutting off of motor torque under emergency working conditions becomes the core requirement for guaranteeing production safety, and the STO function becomes the standard function of the medium-high-end frequency converter. At present, STO function is realized by adopting a high-low level/contact on-off mode in industry, and the key technical scheme is that a frequency converter is provided with STO1/STO2 double-channel input terminals, safety loop components such as an external series emergency stop button, a safety gate switch, a safety relay and the like, the safety relay contacts are directly connected into a loop formed by the STO terminals and a 24V power supply/public end, when the external safety loop is closed, the STO terminals acquire high level or loop conduction, the frequency converter judges that 'output torque is allowed', an IGBT driving module works normally, when emergency stop triggers or the safety gate is opened, the safety relay contacts are disconnected, the STO terminals become low level or open circuit, the frequency converter immediately blocks IGBT driving pulses, and torque output is stopped. However, the existing level STO technology has a plurality of technical defects which are difficult to overcome, the loop state can be judged only through on/off or high/low level, when the open circuit or low level is detected, the state cannot be identified as normal STO trigger caused by active turn-off of an external safety switch or fault state caused by line disconnection and poor contact, the fault positioning is difficult directly, equipment maintenance cost is increased, fault processing is possibly delayed due to misjudgment, production continuity is affected, the safety level is limited due to insufficient redundancy, the double-channel STO is mainly designed as 'double-channel level input', channel uniqueness feature verification is lacked, if the double-channel is broken or a detection circuit fails, the system cannot identify faults, in addition, the prior art, fault visualization and remote monitoring capability are weak, only a single signal of 'STO trigger' can be output, the fault code is not subdivided, the three states of equipment are distinguished through an indicator lamp or a communication interface, remote state monitoring and early warning are not supported, the type of faults can be judged on site only, the maintenance efficiency is reduced, and the risk of non-scheduled shutdown is increased. Disclosure of Invention The invention aims to provide a STO circuit system based on high safety level of frequency converter torque turn-off, which is characterized in that three states of loop turn-on, normal turn-off and line break are accurately distinguished through active pulse excitation-readback verification and matching with frequency and duty ratio differentiation design of double-channel differentiation characteristic pulse, and meanwhile, an isolation design, cross mutual detection, grading drive and MCU closed loop verification four-layer safety protection mechanism is constructed, and the safety level is improved to SIL3/PLe by combining with a grading drive logic of power supply control and enabling setting. The STO circuit system based on the high safety level of the torque turn-off of the frequency converter comprises a STO expansion board and a control board which are mutually and electrically connected, wherein the STO expansion board is an electric signal isolation layer, two paths of independent pulse generation modules, a driving module, a receiving module, a pulse detection module, a level conversion module and an isolation module are arranged in the STO expansion board, a double-channel differential characteristic pulse signal is actively sent, the signal is transmitted to the control board after being returned through an external safety loop and sequentially subjected to pulse detection and level conversion treatment, the control board is a logic control layer, an MCU core unit, a double-independent power module and two paths of PWM driving modules a