Air compressor energy recovery control system and control method

Abstract

The embodiment of the invention provides an air compressor energy recovery control system and method, and relates to the technical field of air compressor energy recovery technologies. The method comprises the following steps: monitoring operation state parameters of the air compressor system in real time; on the basis of the operation state parameters, predictive perception is conducted on a shutdown event of the air compressor system, so that a shutdown preparation instruction is generated; and in response to the shutdown preparation instruction or the external shutdown instruction, executing regenerative braking and recovery operation of transient kinetic energy. According to the invention, the problem of energy waste of the air compressor is solved, so that the effect of improving the energy utilization efficiency is achieved.

Description

Technical Field

[0001] The present invention relates to the field of air compressor energy recovery, and more specifically, to an air compressor energy recovery control system and control method. Background Technology

[0002] Variable frequency air compressors (VFCs) are widely used general-purpose power equipment in industrial production. Their working principle involves a drive motor that rotates the compressor unit (e.g., a screw rotor) at high speed to compress air. During operation, when the pipeline pressure reaches the set upper limit, the air compressor will enter an unloading standby state or stop directly. During shutdown, the high-speed rotating drive motor and compressor unit contain significant rotational kinetic energy.

[0003] Existing technologies typically handle this kinetic energy in two ways: one is through free-gliding to a stop, where the kinetic energy is slowly converted into heat energy and dissipated through mechanical friction and wind resistance, a lengthy process and a complete waste of energy; the other is through a frequency converter connected to a braking resistor for energy-consuming braking, where the kinetic energy is converted into electrical energy and immediately dissipated as heat in the resistor, achieving rapid braking, but still representing a waste of energy. Therefore, existing technologies generally suffer from the technical problem of not being able to effectively utilize the rotational kinetic energy during the stopping process, resulting in significant energy waste. Summary of the Invention

[0004] This invention provides an energy recovery control system and method for an air compressor, which at least solves the problem of energy waste in related technologies.

[0005] According to an embodiment of the present invention, an energy recovery control method for an air compressor is provided, comprising: Real-time monitoring of the operating status parameters of the air compressor system, wherein the operating status parameters include at least the pipeline pressure; Based on the operating status parameters, the shutdown event of the air compressor system is predicted and detected to generate a shutdown preparation command. In response to the shutdown preparation command or the external shutdown command, a regenerative braking and recovery operation of transient kinetic energy is performed. The regenerative braking and recovery operation includes disconnecting the drive motor of the air compressor system from the external power grid, and converting the rotational kinetic energy of the drive motor and the compressor host into electrical energy through the energy recovery module and storing it in the energy storage module.

[0006] In an exemplary embodiment, the step of predictively sensing shutdown events of the air compressor system based on the operating state parameters includes: The pressure of the pipeline network is acquired in real time, and the pressure change rate is calculated. Determine whether the pipeline pressure reaches a first preset pressure threshold and whether the pressure change rate is lower than a preset change rate threshold; If the pipeline pressure reaches the first preset pressure threshold and the pressure change rate is lower than the preset change rate threshold, then it is determined that the shutdown event is about to occur, and the shutdown preparation command is generated.

[0007] In one exemplary embodiment, the regenerative braking and recovery operation for transient kinetic energy includes: Disconnect the electrical connection between the drive motor and the external power grid; The output of the permanent magnet generator is connected to the energy storage module via a bidirectional inverter, wherein the permanent magnet generator is coaxially connected to the drive motor; The rotational kinetic energy is used to drive the permanent magnet generator to generate electricity, and the bidirectional inverter charges the energy storage module until the speed of the drive motor is lower than the preset minimum power generation speed.

[0008] In one exemplary embodiment, after performing the regenerative braking and recovery operation of transient kinetic energy, the method further includes: In response to the start command, determine whether the state of charge of the energy storage module is higher than the preset start-up power threshold; If the state of charge is higher than the preset starting power threshold, the electrical energy stored in the energy storage module is used to drive the drive motor to start, so as to perform auxiliary start-up peak shaving operation.

[0009] In an exemplary embodiment, the step of using the electrical energy stored in the energy storage module to drive the drive motor to start includes: The bidirectional inverter is controlled to operate in inverter mode, converting the DC power from the energy storage module into AC power and supplying it to the drive motor to drive the drive motor to accelerate. When the speed of the drive motor reaches the preset switching speed, the power path management module controls the power supply to switch the power source of the drive motor from the energy storage module to the external power grid.

[0010] In one exemplary embodiment, the method further includes: During the operation of the air compressor system, the power supply status of the external power grid is monitored; When the external power grid is detected to be out of power, the power stored in the energy storage module is used to power the air compressor system.

[0011] According to another embodiment of the present invention, an air compressor energy recovery control system is provided, comprising: A status sensing module is used to monitor the operating status parameters of the air compressor system in real time, wherein the operating status parameters include at least the pipeline pressure; The intelligent control module, connected to the state perception module, is used to predictively perceive shutdown events of the air compressor system based on the operating state parameters, so as to generate shutdown preparation commands; wherein, the intelligent control module is also used to control the energy recovery module to reuse the electrical energy stored in the energy storage module under preset conditions; An energy recovery module, connected to the intelligent control module, is used to convert the rotational kinetic energy of the drive motor and compressor unit of the air compressor system into electrical energy in response to the shutdown preparation command or external shutdown command, and store it in the energy storage module within the energy recovery module. A power path management module, connected to the intelligent control module, is used to disconnect the drive motor from the external power grid when performing the conversion of rotational kinetic energy.

[0012] In an exemplary embodiment, the step of predictively sensing shutdown events of the air compressor system based on the operating state parameters includes: The pressure of the pipeline network is acquired in real time, and the pressure change rate is calculated. Determine whether the pipeline pressure reaches a first preset pressure threshold and whether the pressure change rate is lower than a preset change rate threshold; If the pipeline pressure reaches the first preset pressure threshold and the pressure change rate is lower than the preset change rate threshold, then it is determined that the shutdown event is about to occur, and the shutdown preparation command is generated.

[0013] In one exemplary embodiment, the energy recovery module includes: A permanent magnet generator coaxially connected to the drive motor; A bidirectional inverter connected to the permanent magnet generator and the energy storage module; wherein, under the control of the intelligent control module, the bidirectional inverter is used to rectify the AC power generated by the permanent magnet generator into DC power and charge the energy storage module when converting the rotational kinetic energy, and to invert the DC power of the energy storage module into AC power when reusing the electrical energy.

[0014] In an exemplary embodiment, the intelligent control module is further configured to respond to a start command, determine whether the state of charge of the energy storage module is higher than a preset start-up energy threshold, and when the state of charge is higher than the start-up energy threshold, control the bidirectional inverter to supply the electrical energy stored in the energy storage module to the drive motor to perform auxiliary start-up peak shaving operation until the speed of the drive motor reaches a preset switching speed, and then switch the power supply source to the external power grid through the power path management module.

[0015] This invention accurately predicts shutdown intentions by simultaneously assessing pressure status and pressure change trends, thus providing sufficient preparation time for energy recovery operations and achieving efficient regenerative braking. Furthermore, the recovered electrical energy is used as an auxiliary power source for the next startup, significantly reducing the peak current absorbed from the grid at startup. This solves the technical problems of complete waste of rotational kinetic energy and grid impact during startup found in existing technologies, achieving the beneficial effects of energy conservation and improved power quality. Attached Figure Description

[0016] Figure 1 This is a structural block diagram of an air compressor energy recovery control system according to an embodiment of the present invention; Figure 2 This is a flowchart of an air compressor energy recovery control method according to an embodiment of the present invention; Figure 3 These are simulation diagrams of deceleration curves under different modes according to Embodiment 2 of the present invention; Figure 4 This is a simulation diagram of the optimal power absorption curve according to Embodiment 3 of the present invention. Detailed Implementation

[0017] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0018] In the following description, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0019] Furthermore, in this application, directional terms such as "upper," "lower," "left," and "right" may be defined relative to the orientation of the components shown in the accompanying drawings. It should be understood that these directional terms can be relative concepts, used for relative description and clarification, and may change accordingly depending on the orientation of the components in the accompanying drawings.

[0020] In this application, unless otherwise expressly specified and limited, the term "connection" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a direct connection or an indirect connection through an intermediate medium. Furthermore, the term "coupled" can refer to an electrical connection that enables signal transmission.

[0021] As used herein, “about,” “approximately,” or “approximately” includes the stated value and the average value within an acceptable range of deviation from the given value, wherein the acceptable range of deviation is determined by a person skilled in the art taking into account the measurement under discussion and the error associated with the measurement of the given quantity (i.e., the limitations of the measurement system).

[0022] Example 1 Please see Figure 1 This diagram illustrates a structural block diagram of an air compressor energy recovery control system according to this embodiment. The system can be integrated into a variable frequency air compressor or used as an external module to upgrade an existing variable frequency air compressor. In one specific embodiment, the system includes: a status sensing module 110, an intelligent control module 120, an energy recovery module 130, and a power path management module 140. These modules interact with the air compressor's original powertrain module (including the drive motor 151 and the compressor main unit 152) and the external power grid 160.

[0023] The status sensing module 110 is used to monitor at least one operating status parameter of the air compressor system in real time. In this embodiment, the module includes at least a pressure sensor installed on the air tank or main pipeline to collect pipeline pressure signals at a high frequency (e.g., 100 times per second). Optionally, the module may also include a motor speed sensor (e.g., a rotary encoder or Hall sensor), a current transformer, and a voltage sensor. The motor speed sensor is used to monitor the real-time speed of the drive motor 151; the current transformer is used to monitor the current absorbed by the system from the external power grid 160; and the voltage sensor is used to monitor the voltage status of the external power grid 160. All collected analog or digital signals are then transmitted to the intelligent control module 120 for processing.

[0024] The intelligent control module 120 establishes data and control connections with the state sensing module 110, the energy recovery module 130, and the power path management module 140. This module can be a high-performance programmable logic controller (PLC) or an embedded control board integrating a high-speed microcontroller (MCU). It is used to receive and process data from the state sensing module 110, perform predictive sensing calculations for shutdown events, generate timing control instructions based on the predictive sensing results and system status, so as to control the actions of the energy recovery module 130 and the power path management module 140 respectively, and perform state management on the energy storage module in the energy recovery module 130 (e.g., monitoring the state of charge (SOC), temperature, voltage, etc.).

[0025] The energy recovery module 130 includes a permanent magnet generator 131, a bidirectional inverter 132, and an energy storage module 133. The rotor of the permanent magnet generator 131 is coaxially connected to the main shaft of the drive motor 151 via a coupling or belt, ensuring that its speed is always synchronized with that of the drive motor 151. The AC side of the bidirectional inverter 132 is connected to the output terminal of the permanent magnet generator 131, and its DC side is connected to the energy storage module 133. The energy storage module 133 can be a battery pack composed of multiple lithium-ion battery cells connected in series and parallel, and is equipped with a battery management system (BMS). Under the command of the intelligent control module 120, the bidirectional inverter 132 realizes bidirectional flow of electrical energy: in regenerative braking mode, it acts as a rectifier, efficiently converting the multiphase AC power generated by the permanent magnet generator 131 into DC power to charge the energy storage module 133; in auxiliary start-up mode, it acts as an inverter, converting the DC power stored in the energy storage module 133 into three-phase AC power with controllable frequency and phase to drive the main motor 151.

[0026] Alternatively, the drive motor 151 can be a permanent magnet synchronous motor (PMSM). In this architecture, a separate permanent magnet generator 131 is not required in the energy recovery module 130. When performing regenerative braking and recovery operations for transient kinetic energy, the intelligent control module 120 sends a mode switching command to the frequency converter driving the PMSM (which then functions as a bidirectional inverter 132). The frequency converter switches its operating state from drive mode to four-quadrant regenerative braking mode, transforming the PMSM from a "motor" to a "generator." At this time, the reverse electromagnetic torque generated by the motor brakes the main shaft and converts rotational kinetic energy into electrical energy, which is then fed back to the energy storage module 133 via the frequency converter's DC bus. This integrated implementation not only reduces the number of physical components and installation complexity, lowering hardware costs, but also potentially achieves higher energy recovery efficiency due to the shortened energy conversion chain.

[0027] The power path management module 140 is used to manage the power supply source of the drive motor 151. In this embodiment, the module is a high-speed automatic transfer switch (ATS). The switch has two input terminals and one output terminal. The output terminal is always connected to the power input terminal of the drive motor 151, and the two input terminals are respectively connected to the external power grid 160 and the AC output terminal of the bidirectional inverter 132. Under the control of the intelligent control module 120, the switch can complete the switching of the power supply of the drive motor 151 between the external power grid and the energy storage module in milliseconds.

[0028] Specifically, the intelligent control module 120 uses a Siemens S7-1200 series PLC. Its built-in high-speed counter interface is connected to an incremental encoder installed on the shaft end of the drive motor 151 to accurately acquire speed signals. Its analog input module is connected to a pressure transmitter with a range of 0-16 bar to acquire pipeline pressure. The PLC's digital output points control the coil of the power path management module 140 (an ABB-manufactured automatic transfer switch with a rated current of 250A) and communicate with the bidirectional inverter 132 in the energy recovery module 130 via the CAN bus.

[0029] The permanent magnet generator 131 in the energy recovery module 130 is a 20kW permanent magnet synchronous generator matched with the 75kW drive motor 151, and is connected to the main shaft via a pulley at a speed ratio of 1:1.5. The bidirectional inverter 132 is a custom-designed voltage source inverter based on silicon carbide (SiC) power devices, with a switching frequency of up to 20kHz, enabling high-efficiency energy conversion and high-quality output waveforms. The energy storage module 133 consists of 168 3.7V / 50Ah lithium iron phosphate battery cells connected in series, with a total capacity of approximately 5 kWh, and is monitored and protected by an independent battery management system (BMS). The BMS reports detailed information such as battery SOC, voltage, current, and temperature to the intelligent control module 120 in real time via a CAN bus.

[0030] At the software level, the control program running in the intelligent control module 120 uses a hybrid programming approach combining ladder logic and structured text (SCL). The program incorporates the aforementioned stop intention feedforward prediction algorithm, whose parameters... and It is configured to be adjustable by authorized engineers via a human-machine interface (HMI) to adapt to different gas usage conditions. When performing auxiliary start-up, the PLC sends a preset V / F (voltage / frequency) curve control command to the bidirectional inverter 132 via the CAN bus to achieve a smooth soft start for the motor. The overall system operating status, energy recovery data (e.g., single-cycle recovery, cumulative recovery), and starting current curve can all be displayed and recorded on the HMI, providing users with an intuitive demonstration of energy-saving effects and a basis for system diagnostics.

[0031] like Figure 2 As shown in the figure, this embodiment also provides a detailed explanation of an air compressor energy recovery control method.

[0032] S100: Real-time monitoring of at least one operating status parameter of the air compressor system, wherein the operating status parameter includes at least the pipeline pressure.

[0033] In the initial stage and throughout the entire operation of this embodiment, the intelligent control module 120 continuously and frequently monitors the key operating parameters of the air compressor system through the status sensing module 110 to obtain real-time data streams of pipeline pressure. (i.e., pressure status data); the processor inside the intelligent control module 120 transmits data at fixed time intervals. (For example, The intelligent control module 120 samples the signal returned by the pressure sensor in milliseconds. At this time, the intelligent control module 120 not only records the current pressure value... The data stream will also undergo first-order differencing to calculate the pressure change rate, which reflects the trend in gas demand. (i.e., the trend of pressure change):

[0034] In order to improve To improve stability and reduce fluctuations caused by noise at a single sampling point, a moving average filter can be used to smooth the pressure data over a period of time (e.g., the past 10 sampling points) before differential calculation. In addition to pressure-related parameters, the intelligent control module 120 also monitors the rotational speed of the drive motor 151 simultaneously. and the state of charge of energy storage module 133 Under normal loading (gas production) or unloading (idling) operation, the power path management module 140 connects the drive motor 151 to the external power grid 160, while the electrical path of the energy recovery module 130 is disconnected. Although the permanent magnet generator 131 rotates with the main shaft, it does not generate an electromagnetic load and only constitutes a small mechanical drive load.

[0035] For example, suppose the air compressor is set to operate in a pressure range of 7.0 bar to 8.0 bar; At any given time, the intelligent control module 120 monitors the current pipeline pressure through the status sensing module 110. The pressure was 7.91 bar, and within the past 100 milliseconds, the pressure value linearly increased from 7.90 bar to 7.91 bar; based on this, the intelligent control module 120 calculated the current rate of pressure change. Meanwhile, the motor speed was monitored to be 2950 RPM and the state of charge of the energy storage module 133 was 88%. At this time, the system determined that it was in a normal loading and gas generation state, continued to maintain the current operating mode, and continued to perform monitoring operations.

[0036] S200: Based on at least one operating status parameter, predictively sense shutdown events of the air compressor system to generate shutdown preparation instructions.

[0037] In this embodiment, a shutdown intention feedforward prediction algorithm is run to replace shutdown logic based solely on a pressure upper limit threshold.

[0038] It should be noted that a system about to undergo a prolonged shutdown due to demand saturation will inevitably exhibit two significant characteristics: first, the system pressure is very close to the set upper limit (state characteristic); second, the rate of pressure increase becomes extremely slow, even approaching zero (trend characteristic), the latter reflecting that the system's gas production is already far greater than the current end-user gas consumption. Therefore, only when both conditions are met simultaneously can it be determined with high probability that the system is about to enter a long shutdown or standby window, allowing for the early initiation of energy recovery preparation procedures. If only the condition of pressure reaching the upper limit is relied upon, the system may need to brake immediately upon issuance of the command, resulting in rushed preparation time and impacting recovery efficiency and control smoothness.

[0039] In this embodiment, the execution logic of this step is as follows: The intelligent control module 120 continuously acquires real-time pipeline pressure. and pressure change rate It is compared with two preset thresholds; the first threshold is a first preset pressure threshold. This indicates the lower limit of the pressure range for entering the prediction and judgment interval. This threshold is usually set slightly below the maximum shutdown pressure. ,For example, ,in, It is an adjustable pressure marginal parameter, and its reasonable value range can be adjusted according to the stability of the gas load, that is: , where Q r Q is the rated discharge capacity of the air compressor. min The minimum gas load is given, Δt is the sampling time (10ms recommended), and V p This refers to the pipeline volume; for example, in a factory environment, it can be set within the range of [0.02, 0.1] bars. The second threshold is a preset rate of change threshold. It is used to differentiate the magnitude of gas demand, and its reasonable value range can be calibrated based on the pipeline network volume and load characteristics, i.e. It can typically be set within the range of [0.005, 0.02] bar / s, where Q max To maximize gas load, ensure that forecasting is triggered only when gas demand approaches zero. and When both conditions are met, the intelligent control module 120 determines that a shutdown event is about to occur and immediately generates an internal shutdown preparation command. This command causes the system to enter the "regenerative braking preparation" mode. For example, the controller may start pre-charging or status checking of the bidirectional inverter 132.

[0040] For example, the system parameters are set as follows: maximum shutdown pressure bar, predicting marginal pressure bar, preset rate of change threshold bar / s; therefore, the first preset pressure threshold bar; in At any given moment, the system monitors the pipeline pressure. bar, at this time, satisfies The conditions. Meanwhile, due to a significant reduction in terminal gas consumption, the controller calculates the current pressure change rate. bar / s, this value satisfies The conditions are met; due to the simultaneous triggering of the two conditions, the intelligent control module 120 immediately generates a shutdown preparation command, and the system enters the regenerative braking preparation state. At this time, although the pressure has not yet reached 8.0 bar and no external shutdown command has been received, the system has already anticipated the arrival of the shutdown and is ready for energy recovery.

[0041] S300: In response to a shutdown preparation command or an external shutdown command, it performs regenerative braking and recovery operations for transient kinetic energy.

[0042] This step is executed immediately when the system finally receives a clear shutdown command. The shutdown command can come from several sources: firstly, pipeline pressure... Officially reached or exceeded the maximum shutdown pressure First, the timer running to be unloaded times out; second, the operator presses the manual stop button on the control panel; third, the system receives an emergency stop signal; due to predictive sensing, the system is in a "ready" state in most cases, so it can quickly execute the relevant steps.

[0043] First, upon receiving the shutdown command, the intelligent control module 120 immediately sends a highest-priority control command to the power path management module 140. The high-speed automatic transfer switch activates within an extremely short time (e.g., less than 20 milliseconds), disconnecting the drive motor 151 from the external power grid 160, ensuring that the drive motor 151 becomes an independent energy source driven by rotational kinetic energy. Almost simultaneously, the intelligent control module 120 sends an activation command to the energy recovery module 130. At this time, the bidirectional inverter 132 is activated and operates in rectification charging mode. Its AC input is connected to the stator winding of the permanent magnet generator 131, which is rotating due to inertia, while its DC output is connected to the energy storage module. 133 is switched on; at this time, a charging current controlled by the bidirectional inverter 132 flows through the stator winding of the permanent magnet generator 131. This current generates an electromagnetic resistance torque in the generator that is opposite to the direction of rotation. This resistance torque serves as the main braking torque, acting on the main shaft rigidly connected to the drive motor 151 and the compressor host 152, causing the entire powertrain module to begin to decelerate smoothly and rapidly. During the deceleration process, the rotational kinetic energy of the powertrain module is continuously converted into three-phase AC power by the permanent magnet generator 131, and after rectification by the bidirectional inverter 132, it is continuously charged into the energy storage module 133. This process continues until the speed of the main shaft decreases to a preset minimum generating speed. (For example, below 100 RPM); below this speed, the power generation efficiency is too low, and the intelligent control module 120 will disconnect the bidirectional inverter 132, allowing the system to coast to a complete stop.

[0044] For example, when the pressure reaches 8.0 bar and triggers a shutdown command, the drive motor 151 rotates at 2900 RPM, and the intelligent control module 120 immediately executes the aforementioned steps; assuming the total moment of inertia of the powertrain module is... The rated angular velocity ω = 2πn / 60, where n is the rotational speed, and the overall energy recovery efficiency (from mechanical energy to battery chemical energy) is: Therefore, the initial kinetic energy is When the rotational speed drops to the minimum generating speed During RPM, the remaining kinetic energy is Therefore, the total amount of recoverable mechanical energy is The final electrical energy stored in energy storage module 133 is , conversion The entire deceleration process took 4 seconds, which is much faster than the 20 seconds of natural gliding.

[0045] S400: Under preset conditions, the electrical energy stored in the energy storage module is reused on demand.

[0046] In this embodiment, the stored electrical energy is used to optimize other operational aspects of the air compressor system, a process involving at least two main reuse modes: The first mode is assisted start-up peak shaving operation; when the air compressor starts from a standstill, it needs to overcome huge rotational inertia and static friction, thus absorbing an instantaneous starting current from the power grid far exceeding the rated value. This peak current will impact the power grid. In this embodiment, when the intelligent control module 120 receives the next start command, it first checks the state of charge of the energy storage module 133. ,if If the battery level exceeds a preset starting power threshold (e.g., 60%), auxiliary starting is performed. At this time, the power path management module 140 keeps the drive motor 151 disconnected from the power grid, and the intelligent control module 120 controls the bidirectional inverter 132 to operate in inverter mode, converting the DC power from the energy storage module 133 into three-phase AC power with smoothly increasing voltage and frequency, which is then supplied to the drive motor 151. Since the energy comes entirely from the energy storage module, the current absorbed from the external power grid 160 is zero during this stage. Therefore, the motor accelerates smoothly under the drive of battery power until its speed reaches a preset switching speed. At this point, the motor has already passed the stage of maximum inrush current during startup; optionally, the speed can be switched. The speed can be set to within 30% to 60% of the rated speed of the drive motor to achieve a balance between ensuring smooth start-up and reducing grid impact. At this time, the intelligent control module 120 then controls the power path management module 140 to seamlessly switch the power supply of the drive motor 151 from the bidirectional inverter 132 to the external power grid 160, allowing the grid to take over subsequent acceleration and operation. Additionally, when the energy storage module... When the starting power is below the preset starting power threshold (e.g., 60%), the motor is started by a soft starter on the grid side. The soft starter is selected to match the motor power (e.g., a 100A soft starter corresponds to a 75kW motor), and the starting time is 3-5 seconds.

[0047] For example, when a 75kW air compressor is started directly from the grid, the measured peak current may be as high as 520 amperes (A). However, when performing auxiliary start-up peak shaving, after the start command is issued, the 5 kWh energy storage module first powers the motor to smoothly accelerate to 1500 RPM (the set switching speed) within 3 seconds. During this period, the grid-side current is 0A. When the speed reaches 1500 RPM, the system switches to grid power. At this time, because the motor is already at a higher speed, the peak current absorbed from the grid is only 180 A, which is about 65% lower than that of direct start-up.

[0048] The second mode is uninterruptible power supply (UPS) operation. During normal operation or standby of the air compressor, the intelligent control module 120 continuously monitors the voltage of the external power grid 160 through the status sensing module 110. If an unexpected power outage or severe voltage drop is detected, the intelligent control module 120 can immediately activate the energy storage module 133. At this time, the core control unit of the air compressor system is powered through a preset auxiliary DC-DC conversion circuit. The core control unit includes (but is not limited to) the intelligent control module 120, the human-machine interface display panel, multiple solenoid valves for controlling the on / off of pipelines, and various sensors in the status sensing module 110, to ensure that the system will not "go out of control" in the event of a main power outage, thereby safely preserving the operating state and executing preset shutdown protection procedures, or maintaining basic monitoring functions until the power grid is restored or manual intervention is required. It should be noted that the UPS power supply duration is: , where P c =50W (power consumption of control module), P f =100W (total power consumption of functional devices).

[0049] For example, in a power grid interruption event, the external power supply is interrupted for 500 milliseconds. During this time, a traditional air compressor may trip for protection and require manual reset. However, for an air compressor using this system, the intelligent control module 120 switches to power supply from the energy storage module 133 within 10 milliseconds after detecting the power outage. Subsequently, the control system itself and the display panel continue to operate normally. When the power grid is restored after 500 milliseconds, the system can seamlessly return to the operating state before the power outage, greatly improving the continuity of production and the reliability of the system. The 5kWh energy storage module (SOC=80%) provides power for a duration of T=5000×0.8 / 150=26.7h, which meets the requirements for safe shutdown.

[0050] In addition, to avoid energy waste after the energy storage module is fully charged, the use of recovered energy can be dynamically allocated. Specifically, in each S300 regenerative braking operation, the strategy engine will allocate the recovered energy in real time according to the following priority order: First priority: Charge the recovered energy into the energy storage module until it reaches a state of charge. achieve .

[0051] Second priority: If It has exceeded Then continue charging until it reaches the target level. .

[0052] Third priority: If It has exceeded Then continue charging until the battery reaches its physical charging limit (e.g., 98% SOC). This portion of energy constitutes the overflow energy pool. .

[0053] In this case, when the state of charge of the energy storage module When the powertrain module reaches its physical charging limit, but the regenerative braking process has not yet ended (i.e., there is still a large amount of rotational kinetic energy available for recovery), the system first determines whether the external power grid 160 is stable and whether there is grid connection permission. If the conditions are met, the intelligent control module 120 sends a mode switching command to the bidirectional inverter 132, switching it from charging mode to grid-connected inverter mode. In this mode, the bidirectional inverter 132 uses phase-locked loop (PLL) technology to synchronize with the voltage, frequency, and phase of the external power grid, and smoothly feeds all the electrical energy subsequently recovered from the permanent magnet generator 131 back to the factory's internal power grid in real time.

[0054] At this point, the system reaches a dynamic equilibrium: the instantaneous power recovered from the powertrain... It is converted into power fed back to the grid. ,Right now At this point, the energy storage module itself is no longer charged, but only acts as a stable buffer for the energy flow. In this way, even when the energy storage module is fully charged, the system can still convert all the remaining braking kinetic energy into valuable electrical energy for use, instead of wasting it as heat energy through the braking resistor as in the traditional solution, thus achieving the theoretical maximization of energy utilization.

[0055] For example: An air compressor shuts down after a long period of stable operation, at which point its energy storage module's State of Charge (SOC) has reached 97%. After regenerative braking begins, the recovered energy quickly charges the SOC to the upper limit of 98%. At this point, the braking process is only about 30% complete, and there is still a large amount of kinetic energy. Subsequently, the system immediately activates overflow management, controlling the bidirectional inverter to feed power back to the grid. In the next 2-3 seconds, the inverter continuously converts the remaining kinetic energy into electrical energy and feeds it back to the grid until the motor speed drops below the minimum generating speed, thereby greatly improving the overall energy utilization efficiency of the system.

[0056] In summary, this embodiment transforms the neglected energy dissipation process of air compressor shutdown into a valuable energy recovery process through hardware architecture and intelligent control strategies. The recovered energy is then cleverly applied to solve other technical challenges such as startup shock and power failure protection, forming an efficient and complete energy recycling and system optimization solution.

[0057] Example 2 In certain complex industrial applications, higher demands are placed on the controllability of the braking process itself. For example, in emergency situations, it is necessary to stop as quickly as possible, while in normal, predictable shutdowns, it is desirable to stop in a slightly slower manner but with the highest energy recovery rate.

[0058] To address the technical challenges of adapting to varying operating conditions, the method differs from Embodiment 1 in that it achieves the preset braking performance precisely through real-time feedback and adjustment.

[0059] Specifically, such as Figure 3 As shown, the intelligent control module 120 has at least two preset braking modes for users to select or for the system to automatically determine based on triggering conditions, specifically including "maximum energy saving mode" and "fast response mode".

[0060] Maximum Energy Saving Mode: This mode prioritizes maximizing energy recovery, and the intelligent control module 120 sets a relatively long target braking time. (For example, 5 seconds), and generate a smooth deceleration curve.

[0061] Quick Response Mode: This mode prioritizes minimizing downtime and is typically triggered by an emergency stop signal; in this mode, the intelligent control module 120 sets an extremely short target braking time. (For example, 2 seconds), energy recovery is a secondary consideration in this mode.

[0062] When energy recovery is triggered, the intelligent control module 120 first determines the target braking time for this braking action based on the currently selected braking mode. Then, it initiates a high-frequency closed-loop control cycle, the execution period of which is much shorter than the entire braking duration (e.g., once every 10 milliseconds).

[0063] Within each control cycle, the closed-loop control algorithm performs the following operations: 1. Obtaining Real-Time Speed: The intelligent control module 120 obtains the current real-time speed of the drive motor 151 through the status sensing module 110 (e.g., a rotary encoder on the motor shaft). .

[0064] 2. Calculate the target rotational speed: The intelligent control module 120 calculates the target braking time. and the initial speed at the start of braking Calculate the current time Expected rotational speed .

[0065] 3. Calculate the speed deviation: Compare the target speed with the actual speed to obtain the speed deviation. This deviation value reflects the difference between the actual deceleration process and the expected process. This indicates that the deceleration is too slow; if This indicates that the deceleration was too rapid, and so on.

[0066] 4. Dynamic adjustment of braking torque: The intelligent control module 120 will adjust the speed deviation. As input, the required electromagnetic braking torque is calculated using a built-in PID (proportional-integral-derivative) controller. The output of the PID controller is directly converted into a control command for the bidirectional inverter 132, which precisely adjusts the magnitude of the charging current drawn from the permanent magnet generator 131. Since the electromagnetic braking torque is approximately proportional to the charging current, it can be dynamically adjusted. The system thus achieves real-time and precise control of braking torque.

[0067] The control law of the PID controller can be expressed as:

[0068] in, These are the proportional, integral, and derivative coefficients, which are pre-tuned to ensure the speed, stability, and zero steady-state error of the control system.

[0069] For example, suppose the system receives an emergency stop command and automatically enters "rapid response mode", with a target braking time. Set to 2.0 seconds; initial speed at braking start. For 3000 RPM; in At 10:00, according to the linear deceleration model, the target rotational speed should be 1000 rpm. RPM, at this time, the actual rotational speed measured by the state sensing module 110. It is 2300 RPM; while the speed deviation RPM, a negative value, indicates that the actual deceleration is slower than expected; subsequently, upon receiving this negative deviation, the PID controller will immediately increase its output, thereby instructing the bidirectional inverter 132 to draw a larger charging current from the permanent magnet generator 131.

[0070] It should be noted that the increased charging current leads to a corresponding increase in electromagnetic braking torque, thereby accelerating the deceleration of the powertrain module and causing it to approach the target deceleration curve in the next control cycle. Through this high-frequency "measurement-comparison-adjustment" closed-loop cycle, this embodiment can ensure that the entire braking process is completed precisely according to the preset target time, achieving a high degree of controllability and predictability of braking performance.

[0071] Example 3 Considering the real-time dynamic constraints of each component in the energy recovery chain (especially the energy storage module and power conversion unit), the difference from Embodiment 2 is that this embodiment adjusts the braking control from a simple servo tracking problem to a constrained dynamic optimization problem. Specifically: Phase 1: Generating the optimal power absorption curve for dynamic prediction. In response to a shutdown command, just before entering regenerative braking operation, the intelligent control module 120 in this embodiment does not immediately begin braking, but instead generates an optimal power absorption curve.

[0072] The input to this process is a set of real-time system state constraint parameters, which are acquired by the state-aware module 110 just before braking, and include at least: Energy storage module state of charge (SOC) Batteries can accept higher charging currents at low SOC, but at high SOC (e.g., above 85%), their maximum acceptable charging current will decrease significantly to protect battery life and safety.

[0073] Energy storage module temperature Excessively high or low battery temperatures will also limit its maximum safe charging rate.

[0074] Power conversion unit temperature As a power conversion unit, the bidirectional inverter 132 has an upper limit on the operating temperature of its internal power semiconductor devices (such as IGBTs or SiC). Continuous high-power operation will cause the temperature to rise. If the temperature is too high, its operating power must be actively reduced to prevent damage.

[0075] User-preset strategy: For example, it could be the aforementioned target braking time. Or it could be a sign of a strategy to maximize energy recovery.

[0076] The intelligent control module 120 has a simplified system dynamic model inside. This model stores the relationship between total recovered energy and key variables such as braking power, motor speed, battery charging characteristics, and inverter efficiency in the form of lookup tables or piecewise functions.

[0077] Specifically, at a given initial rotational speed Under the aforementioned real-time state constraints, solve the following optimization problem: Objective: Maximize total recovered energy

[0078] Constraints: 1, (Battery safety charging power constraints) 2, (Inverter thermal safety power constraints) 3, (If a target braking time is specified) 4, (Final speed constraint) In embedded systems, discretized dynamic programming or heuristic algorithms (such as a simplified form of model-based predictive control, MPC) are typically used to solve the problem within tens of milliseconds to obtain results such as... Figure 4 The optimal power absorption curve shown This curve represents time. The function is a curve that plans how much power should be absorbed from the generator at each moment during the entire braking process in order to maximize energy recovery without violating any safety constraints.

[0079] For example: Scenario A: If the battery SOC is detected to be only 30% before braking and the temperature of each component is normal, the system will calculate a power curve that allows energy recovery at a high power close to the system limit during the initial braking phase (when the motor speed is high and the power generation efficiency is high).

[0080] Scenario B: If the battery SOC is detected to be 90% before braking, and the inverter temperature is high due to long-term operation, the power curve calculated by the system will be lower overall and flatter, in order to strictly comply with the charging limit when the battery is at high SOC and the inverter's derating operation requirements. Although the total recovered energy will be less than in Scenario A, the absolute safety of the system is guaranteed.

[0081] Phase Two: Closed-Loop Precision Monitoring of the Optimal Power Curve When the optimal power absorption curve After generation, the intelligent control module 120 immediately enters the regenerative braking execution stage, at which time the PID closed-loop tracking controller is activated.

[0082] Unlike the second embodiment, the monitoring target of the PID controller in this embodiment is power: Obtaining Real-Time Recovered Power: In each control cycle, the intelligent control module 120 calculates the current actual energy recovery power by measuring the voltage and current on the DC side of the bidirectional inverter 132. .

[0083] Calculate power deviation: From the generated curve Find the current time in Target power, calculate power deviation .

[0084] Dynamic adjustment of braking torque: PID controller based on power deviation The adjustment amount is calculated and ultimately converted into a PWM control signal for the bidirectional inverter 132. This signal adjusts the electromagnetic braking torque by changing the current drawn from the permanent magnet generator, thereby forcing... infinitely close .

[0085] By using this two-stage control method of generating the optimal path and following the path, this embodiment transforms the regenerative braking process of the air compressor from a simple energy recovery behavior into an adaptive energy management process aimed at the global optimization of the system.

[0086] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods according to the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal device (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0087] It should be noted that the above modules can be implemented by software or hardware. For the latter, they can be implemented in the following ways, but are not limited to: all the above modules are located in the same processor; or, the above modules are located in different processors in any combination.

[0088] Embodiments of the present invention also provide a computer-readable storage medium storing a computer program, wherein the computer program is configured to perform the steps in any of the above method embodiments when executed.

[0089] In one exemplary embodiment, the aforementioned computer-readable storage medium may include, but is not limited to, various media capable of storing computer programs, such as a USB flash drive, read-only memory (ROM), random access memory (RAM), portable hard disk, magnetic disk, or optical disk.

[0090] Embodiments of the present invention also provide an electronic device including a memory and a processor, the memory storing a computer program and the processor being configured to run the computer program to perform the steps in any of the above method embodiments.

[0091] In one exemplary embodiment, the electronic device may further include a transmission device and an input / output device, wherein the transmission device is connected to the processor and the input / output device is connected to the processor.

[0092] Through the above description of the embodiments, those skilled in the art can clearly understand that, for the sake of convenience and brevity, only the division of the above functional modules is used as an example. In actual applications, the above functions can be assigned to different functional modules as needed, that is, the internal structure of the device can be divided into different functional modules to complete all or part of the functions described above.

[0093] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules or units is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another apparatus, or some features may be ignored or not executed. Furthermore, the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or units may be electrical, mechanical, or other forms.

[0094] The units described as separate components may or may not be physically separate. A component shown as a unit can be one or more physical units; that is, it can be located in one place or distributed in multiple different locations. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0095] Furthermore, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0096] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a readable storage medium. Based on this understanding, the technical solutions of the embodiments of this application, in essence, or the parts that contribute to the prior art, or all or part of the technical solutions, can be embodied in the form of a software product. This software product is stored in a storage medium and includes several instructions to cause a device (which may be a microcontroller, chip, etc.) or processor to execute all or part of the steps of the methods of the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0097] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for controlling energy recovery in an air compressor, characterized in that, include: Real-time monitoring of the operating status parameters of the air compressor system, wherein the operating status parameters include at least the pipeline pressure; Based on the operating status parameters, the shutdown event of the air compressor system is predicted and detected to generate a shutdown preparation command. In response to the shutdown preparation command or the external shutdown command, a regenerative braking and recovery operation of transient kinetic energy is performed. The regenerative braking and recovery operation includes disconnecting the drive motor of the air compressor system from the external power grid, and converting the rotational kinetic energy of the drive motor and the compressor host into electrical energy through the energy recovery module and storing it in the energy storage module.

2. The method according to claim 1, characterized in that, The predictive sensing of shutdown events of the air compressor system based on the operating status parameters includes: The pressure of the pipeline network is acquired in real time, and the pressure change rate is calculated. Determine whether the pipeline pressure reaches a first preset pressure threshold and whether the pressure change rate is lower than a preset change rate threshold; If the pipeline pressure reaches the first preset pressure threshold and the pressure change rate is lower than the preset change rate threshold, then it is determined that the shutdown event is about to occur, and the shutdown preparation command is generated.

3. The method according to claim 1, characterized in that, The regenerative braking and recovery operation for transient kinetic energy includes: Disconnect the electrical connection between the drive motor and the external power grid; The output of the permanent magnet generator is connected to the energy storage module via a bidirectional inverter, wherein the permanent magnet generator is coaxially connected to the drive motor; The rotational kinetic energy is used to drive the permanent magnet generator to generate electricity, and the bidirectional inverter charges the energy storage module until the speed of the drive motor is lower than the preset minimum power generation speed.

4. The method according to claim 3, characterized in that, After performing the regenerative braking and recovery operation of transient kinetic energy, the method further includes: In response to the start command, determine whether the state of charge of the energy storage module is higher than the preset start-up power threshold; If the state of charge is higher than the preset starting power threshold, the electrical energy stored in the energy storage module is used to drive the drive motor to start, so as to perform auxiliary start-up peak shaving operation.

5. The method according to claim 4, characterized in that, The step of using the electrical energy stored in the energy storage module to drive the drive motor to start includes: The bidirectional inverter is controlled to operate in inverter mode, converting the DC power from the energy storage module into AC power and supplying it to the drive motor to drive the drive motor to accelerate. When the speed of the drive motor reaches the preset switching speed, the power path management module controls the power supply to switch the power source of the drive motor from the energy storage module to the external power grid.

6. The method according to claim 1, characterized in that, The method further includes: During the operation of the air compressor system, the power supply status of the external power grid is monitored; When the external power grid is detected to be out of power, the power stored in the energy storage module is used to power the air compressor system.

7. An energy recovery control system for an air compressor, characterized in that, include: A status sensing module is used to monitor the operating status parameters of the air compressor system in real time, wherein the operating status parameters include at least the pipeline pressure; The intelligent control module, connected to the state perception module, is used to predictively perceive shutdown events of the air compressor system based on the operating state parameters, so as to generate shutdown preparation commands; wherein, the intelligent control module is also used to control the energy recovery module to reuse the electrical energy stored in the energy storage module under preset conditions; An energy recovery module, connected to the intelligent control module, is used to convert the rotational kinetic energy of the drive motor and compressor unit of the air compressor system into electrical energy in response to the shutdown preparation command or external shutdown command, and store it in the energy storage module within the energy recovery module. A power path management module, connected to the intelligent control module, is used to disconnect the drive motor from the external power grid when performing the conversion of rotational kinetic energy.

8. The system according to claim 7, characterized in that, The predictive sensing of shutdown events of the air compressor system based on the operating status parameters includes: The pressure of the pipeline network is acquired in real time, and the pressure change rate is calculated. Determine whether the pipeline pressure reaches a first preset pressure threshold and whether the pressure change rate is lower than a preset change rate threshold; If the pipeline pressure reaches the first preset pressure threshold and the pressure change rate is lower than the preset change rate threshold, then it is determined that the shutdown event is about to occur, and the shutdown preparation command is generated.

9. The system according to claim 7, characterized in that, The energy recovery module includes: A permanent magnet generator coaxially connected to the drive motor; A bidirectional inverter connected to the permanent magnet generator and the energy storage module; wherein, under the control of the intelligent control module, the bidirectional inverter is used to rectify the AC power generated by the permanent magnet generator into DC power and charge the energy storage module when converting the rotational kinetic energy, and to invert the DC power of the energy storage module into AC power when reusing the electrical energy.

10. The system according to claim 9, characterized in that, The intelligent control module is also used to respond to the start command, determine whether the state of charge of the energy storage module is higher than the preset start-up power threshold, and when the state of charge is higher than the start-up power threshold, control the bidirectional inverter to supply the electrical energy stored in the energy storage module to the drive motor to perform auxiliary start-up peak shaving operation until the speed of the drive motor reaches the preset switching speed, and then switch the power supply source to the external power grid through the power path management module.

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