EPC Electronic Flow Control Method and System

Abstract

This application discloses an EPC electronic flow control method and system, relating to the field of electrical control technology. The method includes: a control processing unit acquiring an externally input set pressure value and a real-time digital signal representing the fluid pressure within the EPC cavity, output by a pressure feedback unit; determining digital control quantities for each flow path within the EPC based on the set pressure value, the real-time digital signal, and preset PID parameters, wherein the PID parameters are corresponding parameters automatically selected based on different flow ranges; and invoking a drive output unit to perform independent PID closed-loop control on each flow path based on the digital control quantities within a preset differentiated period, where the differentiated period is generated by independent timers configured for different flow paths in a timing unit. This achieves high-precision, low-coupling, and adaptive rhythm-based independent adjustment of each flow path within the EPC, thereby improving the overall control performance and stability of the EPC.

Description

Technical Field

[0001] This application relates to the field of electrical control technology, and in particular to EPC electronic flow control methods and systems. Background Technology

[0002] EPC (Electronic Pressure / Flow Control) modules are widely used in precision analytical equipment such as mass spectrometers and chromatographs. Their control accuracy and stability directly affect the detection accuracy of the analytical equipment. Therefore, precise control of EPC is required.

[0003] Currently, EPC control typically employs a standard closed-loop PID (Proportional-Integral-Derivative) control algorithm and a uniform control cycle to regulate gas flow or pressure. This standard closed-loop PID algorithm usually uses a fixed set of PID parameters. However, in applications with multiple flow paths and wide flow ranges, a single PID parameter is insufficient to simultaneously ensure control accuracy and dynamic response across different flow ranges. Furthermore, the uniform control cycle cannot adapt to the independent dynamic characteristics of different flow paths, leading to mutual interference between flow paths, limiting overall control performance, and resulting in low control accuracy for the EPC.

[0004] The above content is only used to help understand the technical solution of this application and does not represent an admission that the above content is prior art. Summary of the Invention

[0005] The main purpose of this application is to provide an EPC electronic flow control method and system, which aims to solve the technical problem of low control accuracy of EPC in application scenarios with multiple flow paths and wide flow ranges.

[0006] To achieve the above objectives, this application proposes an EPC electronic flow control method, applied to a control processing unit, the method comprising: It acquires the set pressure value input from the outside, as well as the real-time digital signal representing the fluid pressure inside the EPC cavity output by the pressure feedback unit; Based on the set pressure value, the real-time digital signal, and the preset PID parameters, the digital control quantity of each flow path in the EPC is determined. The PID parameters are corresponding parameters automatically selected based on different flow ranges. The drive output unit is invoked to perform independent PID closed-loop control on each of the flow paths based on the digital control quantity within a preset differential period. The differential period is generated by an independent timer configured for different flow paths in the timing unit.

[0007] In one embodiment, the step of determining the digital control quantity of each flow path within the EPC based on the set pressure value, the real-time digital signal, and preset PID parameters includes: Identify the target flow range to which the set pressure value belongs, and retrieve the reference PID control parameters corresponding to the target flow range from the preset PID parameters; Based on the numerical position of the set pressure value within the target flow range, the reference PID control parameters are continuously and dynamically corrected to obtain the target PID parameters for real-time operation. Calculate the pressure deviation between the set pressure value and the real-time digital signal; The pressure deviation value is input into the control logic defined by the target PID parameters for closed-loop processing to obtain the initial control quantity; By combining the pre-calibrated EPC cavity nonlinear characteristic compensation rules, the initial control quantity is corrected to generate the digital control quantity of each flow path.

[0008] In one embodiment, the EPC cavity nonlinear characteristic compensation rule is set for the proportional valve hysteresis effect and valve dead zone characteristics below the preset flow range under radio frequency interference environment during mass spectrometer analysis; The step of modifying the initial control quantity based on the pre-calibrated EPC cavity nonlinear characteristic compensation rules to generate digital control quantities for each flow path includes: The nonlinear compensation coefficients, which characterize the hysteresis of the proportional valve and are stored in the EEPROM memory unit, are used to perform inverse hysteresis compensation on the initial control quantity to obtain the magnetically compensated control quantity. By combining the real-time pressure signal based on the real-time digital signal conversion, it is determined whether the current flow rate is lower than the preset flow rate range; If so, the dead zone feedforward compensation coefficient corresponding to the preset flow range is called from the EEPROM (Electrically Erasable Programmable Read-Only Memory) storage unit, and the dead zone feedforward compensation coefficient is used as the feedforward compensation amount; The feedforward compensation amount is superimposed on the magnetic compensation control amount to generate the digital control amount for each flow path.

[0009] In one embodiment, before determining the digital control quantity of each flow path within the EPC based on the set pressure value, the real-time digital signal, and preset PID parameters, the method further includes: Detect whether the set pressure value jumps from zero to a non-zero value; When the value changes from zero to a non-zero value, the soft-start initial control value and the preset number of executions stored in the EEPROM memory unit are invoked. Using the initial soft-start control quantity as a reference, within the differentiated period generated by the timing unit corresponding to the current flow path, a preset number of PID closed-loop control operations are continuously executed to drive the proportional valve to open. After completing the PID closed-loop control calculation for the preset number of executions, the system automatically executes the steps of determining the digital control quantity of each flow path within the EPC using the set pressure value, the real-time digital signal, and the preset PID parameters, and removes the soft-start restriction on the differentiated cycle.

[0010] In one embodiment, the differentiated cycle includes a speed control cycle configured for the atomizing gas flow path and a stability control cycle configured for the dry gas, backflushing gas, and APCI (Atmospheric Pressure Chemical Ionization) gas flow paths.

[0011] In one embodiment, the real-time digital signal is obtained by the pressure feedback unit converting the fluid pressure in the EPC cavity acquired in real time into an analog signal, performing RC filtering on the analog signal, and then performing digital conversion.

[0012] In one embodiment, before the step of determining the digital control quantity of each flow path within the EPC based on the set pressure value, the real-time digital signal, and preset PID parameters, the method further includes: The real-time digital signal is subjected to moving average filtering and amplitude limiting filtering to obtain a filtered real-time digital signal that eliminates residual jitter and sudden interference. The step of determining the digital control quantity of each flow path within the EPC based on the set pressure value, the real-time digital signal, and the preset PID parameters further includes: Based on the set pressure value, the filtered real-time digital signal, and the preset PID parameters, the digital control quantities of each flow path within the EPC are determined.

[0013] In addition, to achieve the above objectives, this application also proposes an EPC electronic flow control system, which includes: a control processing unit, the control processing unit being electrically connected to a pressure feedback unit, a drive output unit and a timing unit, the timing unit being configured with a corresponding independent timer for different flow paths; The control processing unit is used to acquire the set pressure value input from the outside, receive the real-time digital signal representing the fluid pressure in the EPC cavity output by the pressure feedback unit; determine the digital control quantity of each flow path in the EPC based on the set pressure value, the real-time digital signal and the preset PID parameters, wherein the PID parameters are corresponding parameters automatically selected based on different flow ranges; call the drive output unit and send the target PID parameters to the drive output unit. The pressure feedback unit is used to acquire and characterize the fluid pressure inside the EPC cavity, and generate a real-time digital signal based on the fluid pressure and send it to the control processing unit. The drive output unit is used to receive the target PID parameters and, based on the control of the control processing unit, perform independent PID closed-loop control on each flow path based on the digital control quantity within a preset differentiated period. The independent timer is used to generate differentiated periods for each of the traffic paths.

[0014] In one embodiment, the pressure feedback unit is further configured to convert the fluid pressure in the EPC cavity acquired in real time into an analog signal; perform RC filtering on the analog signal; and convert the RC-filtered analog signal into a real-time digital signal.

[0015] In one embodiment, the timing unit is further configured to generate timing interrupt signals of different periods through different flow path configurations, triggering the control processing unit to periodically execute PID closed-loop control.

[0016] One or more technical solutions proposed in this application have at least the following technical effects: The control processing unit acquires the set pressure value from the external input and the real-time digital signal representing the fluid pressure inside the EPC cavity output by the pressure feedback unit. Based on the set pressure value, the real-time digital signal, and the preset PID parameters, it determines the digital control quantity for each flow path within the EPC, where the PID parameters are automatically selected based on different flow ranges. The drive output unit is invoked to perform independent PID closed-loop control on each flow path based on the digital control quantity within a preset differential period. The differential period is generated by an independent timer configured for different flow paths in the timing unit. Therefore, by automatically selecting the corresponding target PID parameters according to different flow ranges, control can be achieved using PID parameters adapted to the dynamic characteristics during wide-range operation. This fixes the PID parameters' response hysteresis in the low-flow range and overshoot oscillation in the high-flow range, improving the control accuracy and dynamic response performance of the EPC in multi-flow-path, wide-range scenarios. Simultaneously, by configuring differentiated periods generated by independent timers for each flow path and executing independent PID closed-loop control within their respective differentiated periods, different flow paths can operate at appropriate control frequencies based on their own hydrodynamic characteristics, avoiding control pace conflicts and mutual interference between flow paths caused by using a uniform control period. This achieves high-precision, low-coupling, and adaptive independent adjustment of each flow path of the EPC, thereby improving the overall control performance and stability of the EPC. Attached Figure Description

[0017] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0018] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart illustrating an embodiment of the EPC electronic flow control method of this application. Figure 2 This is a flowchart illustrating Embodiment 2 of the EPC electronic flow control method of this application. Figure 3 This is a flowchart illustrating Embodiment 3 of the EPC electronic flow control method of this application; Figure 4 This is a schematic diagram of the module structure of the EPC electronic flow control system according to an embodiment of this application.

[0020] The realization of the purpose, functional features and advantages of this application will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0021] It should be understood that the specific embodiments described herein are merely illustrative of the technical solutions of this application and are not intended to limit this application.

[0022] It should be noted that the executing entity in this embodiment can be a computing service device with data processing, network communication, and program execution functions, such as a tablet computer, personal computer, or mobile phone, or an electronic device or control processing unit capable of performing the above functions. The following description uses a control processing unit as an example to illustrate this embodiment and the subsequent embodiments.

[0023] Based on this, the embodiments of this application provide an EPC electronic flow control method, referring to... Figure 1 , Figure 1 This is a flowchart illustrating an embodiment of the EPC electronic flow control method of this application.

[0024] In this embodiment, the EPC electronic flow control method includes steps S10~S30: Step S10: Obtain the set pressure value input from the outside and the real-time digital signal output by the pressure feedback unit that represents the fluid pressure inside the EPC cavity. It should be noted that the set pressure value is the target pressure value input by the user through the human-machine interface or host computer software, representing the desired fluid pressure level maintained in the EPC cavity. The pressure feedback unit is a high-precision piezoresistive or capacitive pressure sensor. The real-time digital signal is obtained by the pressure feedback unit converting the real-time fluid pressure in the EPC cavity into an analog signal, performing RC filtering on the analog signal, and then performing digital conversion.

[0025] It is understandable that by outputting a real-time digital signal representing the fluid pressure inside the EPC cavity through the pressure feedback unit, the actual state inside the cavity can be fed back to the control processing unit in a high-precision and low-latency manner.

[0026] Understandably, combining target commands with real-time status avoids control inaccuracies caused by missing or delayed information, thereby effectively improving the response speed and control stability of the entire EPC.

[0027] In practice, the user inputs a set pressure value representing the desired gas pressure level through the workstation software or human-machine interface accompanying the analyzer. Simultaneously, the pressure feedback unit in the EPC electronic flow control system converts the fluid pressure within the EPC chamber, which is acquired in real time, into an analog voltage signal with a linear relationship to the pressure. This analog voltage signal is then RC-filtered to generate a real-time digital signal. The pressure sensor features on-chip temperature compensation to eliminate the impact of ambient temperature fluctuations on pressure acquisition accuracy. Furthermore, the RC filter circuit employs a series low-pass filter structure to effectively filter out high-frequency interference components in the signal, particularly strong electromagnetic interference from the mass spectrometer's radio frequency source.

[0028] Specifically, the real-time digital signal converted from the analog voltage signal after RC filtering can be sent to the analog-to-digital converter chip. The analog-to-digital converter chip can be the built-in chip of the pressure feedback unit. The analog-to-digital converter chip converts the analog signal into a discrete digital signal and transmits it to the control processing unit.

[0029] Step S20: Based on the set pressure value, the real-time digital signal, and the preset PID parameters, determine the digital control quantity of each flow path in the EPC. The PID parameters are corresponding parameters automatically selected based on different flow ranges. It should be noted that PID parameters are a set of proportional coefficient, integral time or integral gain, and derivative time or derivative gain. The digital control quantity is the PWM duty cycle or DAC voltage value output from the PID calculation, used to drive the proportional valve. This value is generated after nonlinear compensation correction and directly determines the valve opening. The flow range is the division of the EPC system's operating flow range into several continuous or discrete segments (e.g., 0-20% full scale, 20%-100% full scale; 0–5 mL / min, 5–20 mL / min, 20–100 mL / min), with each segment corresponding to a set of optimized baseline PID parameters.

[0030] Understandably, fixed PID parameter control strategies struggle to accommodate the varying dynamic characteristics of different flow ranges, performing well in one range but exhibiting overshoot or sluggish response in another. Therefore, in this embodiment, the operating flow is divided into multiple ranges, and optimal target PID parameters are preset and automatically selected for each range. This allows the control algorithm to adaptively match the current operating conditions, enabling the use of PID parameters emphasizing fast response to shorten settling time in high flow ranges, and PID parameters emphasizing stability to suppress minor fluctuations in low flow ranges. This achieves high-precision, low-fluctuation flow control across the entire operating range.

[0031] In its implementation, the control processing unit incorporates multiple independent segmented PID control algorithms, each corresponding to a specific gas flow rate (e.g., atomizing gas flow rate, drying gas flow rate, backflushing gas flow rate, APCI gas flow rate). For each flow rate, the segmented PID control algorithm pre-sets different PID parameter sets based on the number of flow ranges, each corresponding to a specific flow range. For example, the flow range can be divided into a small flow range of 0-20% of full scale and a large flow range of 20%-100% of full scale. When performing control calculations, the control processing unit first determines the flow range of the current set pressure value and automatically calls the optimal PID parameter set corresponding to that range. Then, based on the selected PID parameters, the deviation between the set pressure value and the real-time digital signal, the control processing unit performs PID calculations to generate a basic digital control quantity.

[0032] Optionally, during the startup phase of the EPC electronic flow control system, if the set pressure value is detected to jump from zero to a non-zero value, the control processing unit can also prioritize the execution of soft-start logic. That is, it first performs several preset PID closed-loop control cycles with a fixed initial control quantity. After the EPC electronic flow control system has initially stabilized, it switches to the above-mentioned conventional closed-loop control mode based on segmented PID parameters to avoid flow overshoot or drastic fluctuations at the moment of startup.

[0033] Optionally, since there may be residual jitter in the real-time digital signal or sudden interference, the EPC electronic flow control method may further include the following before step S02: The real-time digital signal is subjected to moving average filtering and amplitude limiting filtering to obtain a filtered real-time digital signal that eliminates residual jitter and sudden interference.

[0034] It should be noted that moving average filtering uses the arithmetic mean of N consecutive sampled data points as the current valid value to effectively smooth random noise and small fluctuations. Amplitude limiting filtering sets a maximum allowable change threshold. When the change between two adjacent sampled values ​​exceeds this threshold, the current sampled value is forcibly corrected to the previous valid value (or other limiting processing is performed), thereby suppressing sudden interference or spikes.

[0035] Understandably, by implementing a combined digital filtering logic of moving average filtering and amplitude limiting filtering within the control processing unit, a deep anti-interference system integrating hardware and software is constructed. Amplitude limiting filtering accurately identifies and eliminates abnormal data points that exceed physically reasonable ranges caused by sudden interference, preventing these abnormal data points from contaminating control decisions. Moving average filtering effectively smooths out minor signal fluctuations caused by various random factors, improving the smoothness and signal-to-noise ratio of the feedback signal. Therefore, the filtered real-time digital signal obtained after this dual filtering process can more realistically and stably reflect the actual pressure state within the EPC cavity.

[0036] Furthermore, step S02 can also be: Based on the set pressure value, the filtered real-time digital signal, and the preset PID parameters, the digital control quantities of each flow path within the EPC are determined.

[0037] Step S30: Invoke the drive output unit to perform independent PID closed-loop control on each flow path based on the digital control quantity within a preset differential period. The differential period is generated by an independent timer configured for different flow paths in the timing unit.

[0038] It should be noted that the differentiated cycle is an independent control sampling and update cycle configured for different flow paths (such as atomizing gas and drying gas). It can include the speed control cycle configured for the atomizing gas flow path, as well as the stability control cycle configured for the drying gas, backflushing gas and APCI gas flow paths.

[0039] Understandably, in complex analytical instruments (such as mass spectrometers), the control performance requirements for different gas flow paths (e.g., nebulized gas, drying gas) vary significantly. For example, the nebulized gas path requires extremely fast dynamic response to match the gradient changes in liquid chromatography, while the drying gas path prioritizes long-term stability to maintain a constant ion source environment. Using a uniform control cycle cannot simultaneously meet the needs of all flow paths. Therefore, in this embodiment, by configuring independent timers for each flow path, differentiated control cycles are generated, enabling a precise control strategy that allocates control based on demand. For instance, configuring a high-speed control cycle for the nebulized gas path ensures its instantaneous tracking capability against changes in setpoints; while configuring a low-speed control cycle for steady-state gas paths such as drying gas satisfies stability requirements and effectively reduces the computational load on the control processing unit and the switching losses of the drive unit. This not only optimizes the control performance of each flow path but also improves the overall operating efficiency and reliability at the EPC electronic flow control system level.

[0040] This embodiment provides an EPC electronic flow control method. The control processing unit acquires the set pressure value input from the outside and the real-time digital signal representing the fluid pressure inside the EPC cavity output by the pressure feedback unit. Based on the set pressure value, the real-time digital signal, and preset PID parameters, the digital control quantity of each flow path in the EPC is determined, wherein the PID parameters are corresponding parameters automatically selected based on different flow ranges. The drive output unit is invoked to perform independent PID closed-loop control on each flow path based on the digital control quantity within a preset differential period. The differential period is generated by an independent timer configured for different flow paths in the timing unit. Therefore, by automatically selecting the corresponding target PID parameters according to different flow ranges, control can be achieved using PID parameters adapted to the dynamic characteristics during wide-range operation. This avoids the response lag in low-flow ranges and overshoot oscillation in high-flow ranges caused by fixed PID parameters, thus improving the control accuracy and dynamic response performance of the EPC in multi-flow-path, wide-range scenarios. Simultaneously, by configuring differentiated periods generated by independent timers for each flow path and executing independent PID closed-loop control within their respective differentiated periods, different flow paths can operate at appropriate control frequencies based on their own hydrodynamic characteristics, avoiding control pace conflicts and mutual interference between flow paths caused by using a unified control period. This achieves high-precision, low-coupling, and adaptive independent adjustment of each flow path of the EPC, thereby improving the overall control performance and stability of the EPC.

[0041] Based on Embodiment 1 of this application, in Embodiment 2 of this application, the content that is the same as or similar to that in Embodiment 1 can be referred to the above description, and will not be repeated hereafter. Based on this, please refer to... Figure 2 Step S20 also includes steps S01 to S05: Step S01: Identify the target flow range to which the set pressure value belongs, and retrieve the reference PID control parameters corresponding to the target flow range from the preset PID parameters; Step S02: Based on the numerical position of the set pressure value within the target flow range, continuously and dynamically correct the reference PID control parameters to obtain the target PID parameters for real-time operation. Step S03: Calculate the pressure deviation between the set pressure value and the real-time digital signal; Step S04: Input the pressure deviation value into the control operation logic defined by the target PID parameters for closed-loop processing to obtain the initial control quantity; Step S05: Based on the pre-calibrated EPC cavity nonlinear characteristic compensation rules, the initial control quantity is corrected to generate the digital control quantity for each flow path.

[0042] It should be noted that the target flow range is the flow interval to which the set pressure value belongs. The baseline PID control parameters are a set of basic proportional, integral, and derivative coefficients determined during the offline calibration phase using system identification and optimization algorithms for a specific target flow range. These parameters are used as the initial parameters for control operations within that range. The numerical position is the relative position of the set pressure value within its target flow range. The real-time target PID parameters are the actual PID parameters used for the current control cycle, obtained by dynamically correcting the baseline PID control parameters based on the numerical position of the set pressure value within the target flow range. The pressure deviation value is the algebraic difference between the set pressure value and the filtered real-time digital signal within any control cycle. The control operation logic is a discretized PID control equation defined by the real-time target PID parameters, implemented in the control processing unit, used to convert the pressure deviation value into the initial control quantity. The initial control quantity is the raw digital control signal, calculated directly by the control processing unit through the execution of the control operation logic, without nonlinear compensation. The EPC cavity nonlinear characteristic compensation rule is a data model or lookup table obtained through comprehensive calibration experiments before leaving the factory. It is used to describe and compensate for the inherent nonlinear characteristics (such as hysteresis, dead zone, and saturation effect) of the EPC cavity and proportional valve. Among them, the EPC cavity nonlinear characteristic compensation rule can be set for the proportional valve hysteresis effect and valve dead zone characteristics below the preset flow range under radio frequency interference environment during mass spectrometry analysis.

[0043] Understandably, current EPC control methods typically employ fixed PID parameters or only perform simple segmented switching, failing to address subtle differences in operating conditions within the same segment. Furthermore, they generally ignore the nonlinear characteristics of the actuator, resulting in limited control accuracy, particularly in ultra-low flow ranges. Therefore, this embodiment resolves the fundamental contradiction of vastly different dynamic characteristics across different flow ranges by identifying the target flow segment and retrieving the reference PID parameters, laying the foundation for achieving high-performance control across the entire flow range. Secondly, the design of continuously and dynamically correcting the reference parameters based on numerical position allows the control parameters to change smoothly and continuously as the setpoint moves within the segment, avoiding control discontinuities and performance abrupt changes caused by segmented switching, thereby achieving truly seamless, high-precision control across the entire flow range.

[0044] It is understandable that even with perfectly matched PID parameters, the final control accuracy will still fluctuate if the nonlinear effects such as the dead zone and hysteresis of the proportional valve are not compensated. Therefore, in this embodiment, the initial control quantity generated is nonlinearly corrected before the final digital control quantity is generated. This is equivalent to adding an inverse model at the end of the control link, thereby offsetting the defects of the physical actuator and enabling the theoretical control command to be executed accurately.

[0045] Furthermore, step S05 may also include: The nonlinear compensation coefficients, which characterize the hysteresis of the proportional valve and are stored in the EEPROM memory unit, are used to perform inverse hysteresis compensation on the initial control quantity to obtain the magnetically compensated control quantity. By combining the real-time pressure signal based on the real-time digital signal conversion, it is determined whether the current flow rate is lower than the preset flow rate range; If so, the dead zone feedforward compensation coefficient corresponding to the preset flow range is called in the EEPROM storage unit, and the dead zone feedforward compensation coefficient is used as the feedforward compensation amount. The feedforward compensation amount is superimposed on the magnetic compensation control amount to generate the digital control amount for each flow path.

[0046] It should be noted that the hysteresis characteristic of a proportional valve is a physical phenomenon caused by internal mechanical friction, residual magnetism, and other factors during the forward (opening wide) and reverse (closing wide) regulation processes, resulting in inconsistent output flow or pressure under the same input control signal. Inverse hysteresis compensation utilizes pre-stored hysteresis characteristic data to construct an inverse model. Given a desired output, this inverse model can calculate the corrected input signal needed to overcome the hysteresis effect. The hysteresis compensation control quantity is an intermediate control signal obtained by applying inverse hysteresis compensation to the initial control quantity; this signal can counteract the negative impact of proportional valve hysteresis. The real-time pressure signal is a pressure value with engineering units in the physical world, converted from a real-time digital signal through the inverse mapping relationship (i.e., calibration curve) of an analog-to-digital converter chip. The dead-zone feedforward compensation coefficient is a fixed or setpoint-related compensation quantity obtained through experimental calibration for a preset flow range before leaving the factory. The feedforward compensation quantity is a compensation signal actively applied outside the control loop based on prior knowledge of system disturbances or inherent defects.

[0047] Understandably, hysteresis causes the system's paths to misalign during back-and-forth adjustments, severely impacting control repeatability and accuracy. Dead zones, on the other hand, result in no system response to minute signals, leading to inaccurate control or even loss of control at ultra-low flow rates. Currently, solutions typically focus on only one problem or employ overly simplistic compensation methods, which are insufficient to achieve satisfactory results in demanding mass spectrometry applications. In this embodiment, inverse hysteresis compensation is first performed by invoking nonlinear compensation coefficients, fundamentally avoiding control path inconsistencies caused by the internal physical characteristics of the proportional valve. This ensures that EPC electronic flow control follows the same precise control curve whether adjusting from high to low flow or from low to high flow, thereby improving the reproducibility and reliability of gas path switching in multi-gradient analysis methods. Furthermore, by combining real-time pressure signals to identify dead zone conditions and applying feedforward compensation, feedback control failure within the dead zone is prevented. In other words, because feedforward compensation is an open-loop, active intervention method, it does not rely on the generation of deviations but can apply sufficient driving force to overcome the dead zone before deviations occur. This allows the EPC to remain linearly controllable even under extreme operating conditions with near-zero flow, successfully extending the effective control range downwards, thus meeting the urgent need of high-sensitivity mass spectrometers for precise control of gas flow rates in nanoliters and even picoliters.

[0048] Based on Embodiments 1 and 2 of this application, the same or similar content in Embodiment 3 of this application can be referred to the above description, and will not be repeated hereafter. Please refer to [the above description]. Figure 3 Before step S20, the EPC electronic flow control method further includes steps S1 to S4: Step S1: Detect whether the set pressure value jumps from zero to a non-zero value; Step S2: When the value changes from zero to a non-zero value, the soft-start initial control value and the preset number of executions stored in the EEPROM memory unit are invoked. Step S3: Using the initial soft-start control quantity as a reference, within the differentiated period generated by the timing unit corresponding to the current flow path, continuously execute PID closed-loop control calculations for a preset number of executions to drive the proportional valve to open. Step S4: After completing the PID closed-loop control calculation for the preset number of executions, automatically execute the set pressure value, the real-time digital signal, and the preset PID parameters to determine the digital control quantity of each flow path in the EPC, and remove the soft-start restriction on the differentiated cycle.

[0049] It should be noted that a zero value represents the pressure setpoint indicating that the corresponding flow path of the EPC module is in a completely closed state. A non-zero value is any pressure setpoint greater than zero, representing the user's expectation to open the flow path and establish a certain gas flow rate. The soft-start initial control quantity is a fixed, safe digital drive signal preset during the startup phase of the EPC electronic flow control system to smoothly open the proportional valve. The preset execution count is a fixed number of cycles during the soft-start phase, based on the soft-start initial control quantity, to continuously execute PID closed-loop control calculations. The proportional valve is the core actuator in the EPC module; its opening degree is continuously adjusted by the input electrical signal, thereby precisely controlling the gas flow rate.

[0050] Understandably, in a gas flow control system, directly applying a large control input from a zero-flow state to open a proportional valve can easily lead to a sudden breach of the valve's dead zone, resulting in a severe instantaneous overshoot in flow or pressure. Therefore, in this embodiment, by detecting the transition and recalling a pre-stored safe initial value, the risk of using an unverified, potentially excessively large initial drive signal can be fundamentally avoided. Then, a limited number of closed-loop fine-tuning operations are performed based on this safe initial value, effectively suppressing any potential fluctuations during startup.

[0051] In practical implementation, for application scenarios that are extremely sensitive to shocks, a multi-level progressive soft-start strategy can also be adopted. That is, a soft-start control sequence (e.g., C1, C2, C3) and the corresponding number of sub-stage executions can be stored in the EEPROM. When the EPC electronic flow control system starts, it first runs N1 times with C1, then N2 times with C2, and finally N3 times with C3, so as to gradually increase the driving intensity, thereby achieving a disturbance-free ultra-smooth start-up, which can be used for mass spectrometers that are sensitive to airflow stability.

[0052] It should be noted that the above examples are only for understanding this application and do not constitute a limitation on the EPC electronic flow control method of this application. Any simple modifications based on this technical concept are within the protection scope of this application.

[0053] This application also provides an EPC electronic flow control system; please refer to... Figure 4 The EPC electronic flow control system includes: The control processing unit is electrically connected to a pressure feedback unit, a drive output unit, and a timing unit. The timing unit is configured with a corresponding independent timer for different flow paths. The control processing unit is used to acquire the set pressure value input from the outside, receive the real-time digital signal representing the fluid pressure in the EPC cavity output by the pressure feedback unit; determine the digital control quantity of each flow path in the EPC based on the set pressure value, the real-time digital signal and the preset PID parameters, wherein the PID parameters are corresponding parameters automatically selected based on different flow ranges; call the drive output unit and send the target PID parameters to the drive output unit. The pressure feedback unit is used to acquire and characterize the fluid pressure inside the EPC cavity, and generate a real-time digital signal based on the fluid pressure and send it to the control processing unit. The drive output unit is used to receive the target PID parameters and, based on the control of the control processing unit, perform independent PID closed-loop control on each flow path based on the digital control quantity within a preset differentiated period. The independent timer is used to generate differentiated periods for each of the traffic paths.

[0054] Furthermore, the pressure feedback unit is also used to convert the fluid pressure in the EPC cavity acquired in real time into an analog signal; to perform RC filtering on the analog signal; and to convert the RC-filtered analog signal into a real-time digital signal.

[0055] Furthermore, the timing unit is also used to generate timing interrupt signals of different periods through different flow path configurations, triggering the control processing unit to periodically execute PID closed-loop control.

[0056] Furthermore, the control processing unit is also connected to an EEPROM storage unit, which stores parameters such as PID, timer, and soft start corresponding to the drying gas, atomizing gas, backflush gas, and APCI gas. Each time the EPC electronic flow control system is powered on, the control processing unit automatically reads the parameters in the EEPROM storage unit to complete the initialization. At the same time, the control processing unit has a configuration parameter debugging interface, which allows the PID and other parameters to be modified via a host computer. The modified data is stored in real time in the EEPROM storage unit for easy debugging and optimization later.

[0057] The EPC electronic flow control system provided in this application, employing the EPC electronic flow control method in the above embodiments, can solve the technical problem of low control accuracy of EPC in application scenarios with multiple flow paths and wide flow ranges. Compared with the prior art, the beneficial effects of the EPC electronic flow control system provided in this application are the same as those of the EPC electronic flow control method provided in the above embodiments, and other technical features in the EPC electronic flow control system are the same as those disclosed in the methods of the above embodiments, and will not be repeated here.

[0058] The above description is only a part of the embodiments of this application and does not limit the scope of protection of this application. All equivalent structural transformations made under the technical concept of this application and using the content of this application specification and drawings, or direct / indirect applications in other related technical fields, are included in the scope of protection of this application.

Claims

1. An EPC electronic flow control method, characterized in that, Applied to a control processing unit, the method includes: It acquires the set pressure value input from the outside, as well as the real-time digital signal representing the fluid pressure inside the EPC cavity output by the pressure feedback unit; Based on the set pressure value, the real-time digital signal, and the preset PID parameters, the digital control quantity of each flow path in the EPC is determined. The PID parameters are corresponding parameters automatically selected based on different flow ranges. The drive output unit is invoked to perform independent PID closed-loop control on each of the flow paths based on the digital control quantity within a preset differential period. The differential period is generated by an independent timer configured for different flow paths in the timing unit.

2. The EPC electronic flow control method as described in claim 1, characterized in that, The step of determining the digital control quantity of each flow path within the EPC based on the set pressure value, the real-time digital signal, and the preset PID parameters includes: Identify the target flow range to which the set pressure value belongs, and retrieve the reference PID control parameters corresponding to the target flow range from the preset PID parameters; Based on the numerical position of the set pressure value within the target flow range, the reference PID control parameters are continuously and dynamically corrected to obtain the target PID parameters for real-time operation. Calculate the pressure deviation between the set pressure value and the real-time digital signal; The pressure deviation value is input into the control logic defined by the target PID parameters for closed-loop processing to obtain the initial control quantity; By combining the pre-calibrated EPC cavity nonlinear characteristic compensation rules, the initial control quantity is corrected to generate the digital control quantity of each flow path.

3. The EPC electronic flow control method as described in claim 2, characterized in that, The EPC cavity nonlinear characteristic compensation rule is set for the proportional valve hysteresis effect and valve dead zone characteristics below the preset flow range under radio frequency interference environment during mass spectrometry analysis. The step of modifying the initial control quantity based on the pre-calibrated EPC cavity nonlinear characteristic compensation rules to generate digital control quantities for each flow path includes: The nonlinear compensation coefficients, which characterize the hysteresis of the proportional valve and are stored in the EEPROM memory unit, are used to perform inverse hysteresis compensation on the initial control quantity to obtain the magnetically compensated control quantity. By combining the real-time pressure signal based on the real-time digital signal conversion, it is determined whether the current flow rate is lower than the preset flow rate range; If so, the dead zone feedforward compensation coefficient corresponding to the preset flow range is called in the EEPROM storage unit, and the dead zone feedforward compensation coefficient is used as the feedforward compensation amount. The feedforward compensation amount is superimposed on the magnetic compensation control amount to generate the digital control amount for each flow path.

4. The EPC electronic flow control method as described in claim 1, characterized in that, Before determining the digital control values ​​of each flow path within the EPC based on the set pressure value, the real-time digital signal, and the preset PID parameters, the method further includes: Detect whether the set pressure value jumps from zero to a non-zero value; When the value changes from zero to a non-zero value, the soft-start initial control value and the preset number of executions stored in the EEPROM memory unit are invoked. Using the initial soft-start control quantity as a reference, within the differentiated period generated by the timing unit corresponding to the current flow path, a preset number of PID closed-loop control operations are continuously executed to drive the proportional valve to open. After completing the PID closed-loop control calculation for the preset number of executions, the system automatically executes the steps of determining the digital control quantity of each flow path within the EPC using the set pressure value, the real-time digital signal, and the preset PID parameters, and removes the soft-start restriction on the differentiated cycle.

5. The EPC electronic flow control method as described in claim 1, characterized in that, The differentiated cycles include a speed control cycle configured for the atomizing gas flow path and a stability control cycle configured for the dry gas, backflushing gas, and APCI gas flow paths.

6. The EPC electronic flow control method as described in claim 1, characterized in that, The real-time digital signal is obtained by the pressure feedback unit converting the fluid pressure in the EPC cavity into an analog signal, performing RC filtering on the analog signal, and then performing digital conversion.

7. The EPC electronic flow control method as described in claim 1, characterized in that, Before determining the digital control values ​​of each flow path within the EPC based on the set pressure value, the real-time digital signal, and the preset PID parameters, the method further includes: The real-time digital signal is subjected to moving average filtering and amplitude limiting filtering to obtain a filtered real-time digital signal that eliminates residual jitter and sudden interference. The step of determining the digital control quantity of each flow path within the EPC based on the set pressure value, the real-time digital signal, and the preset PID parameters further includes: Based on the set pressure value, the filtered real-time digital signal, and the preset PID parameters, the digital control quantities of each flow path within the EPC are determined.

8. An EPC electronic flow control system for performing the method according to any one of claims 1 to 7, characterized in that, The system includes: a control processing unit, which is electrically connected to a pressure feedback unit, a drive output unit and a timing unit, and the timing unit is configured with a corresponding independent timer for different flow paths; The control processing unit is used to acquire the set pressure value input from the outside, receive the real-time digital signal representing the fluid pressure in the EPC cavity output by the pressure feedback unit; determine the digital control quantity of each flow path in the EPC based on the set pressure value, the real-time digital signal and the preset PID parameters, wherein the PID parameters are corresponding parameters automatically selected based on different flow ranges; call the drive output unit and send the target PID parameters to the drive output unit. The pressure feedback unit is used to acquire and characterize the fluid pressure inside the EPC cavity, and generate a real-time digital signal based on the fluid pressure and send it to the control processing unit. The drive output unit is used to receive the target PID parameters and, based on the control of the control processing unit, perform independent PID closed-loop control on each flow path based on the digital control quantity within a preset differentiated period. The independent timer is used to generate differentiated periods for each of the traffic paths.

9. The EPC electronic flow control system as described in claim 8, characterized in that, The pressure feedback unit is also used to convert the fluid pressure in the EPC cavity acquired in real time into an analog signal; to perform RC filtering on the analog signal; and to convert the RC-filtered analog signal into a real-time digital signal.

10. The EPC electronic flow control system as described in claim 8, characterized in that, The timing unit is also used to generate timing interrupt signals of different periods through different flow path configurations, triggering the control processing unit to periodically execute PID closed-loop control.

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