Energy storage device and control method for a large servo press

Abstract

The application provides an energy storage device and a control method of a large servo press, and belongs to the technical field of industrial automation control. The method comprises the following steps: when the main servo drive system is powered on, the super capacitor energy storage module is limited current pre-charged; when the servo press slider is decelerated, braked or backhauled, the braking electric energy is fed back to the DC bus, and the super capacitor energy storage module is charged when the bus voltage is higher than the terminal voltage of the super capacitor; when the slider goes down into the forming working condition, the DC bus voltage drops, and the super capacitor energy storage module discharges to the DC bus when the bus voltage is lower than the terminal voltage of the super capacitor, and the super capacitor energy storage module and the rectifying unit jointly supply power to the main servo motor; the device comprises a main servo drive system, a super capacitor energy storage module, a pre-charging loop control module, a stamping working loop module, a CMS monitoring system and a safety protection module. The application realizes the recovery of braking energy and the compensation of instantaneous power by taking the super capacitor as an energy medium, stabilizes the bus voltage and improves the stamping precision.

Description

Technical Field

[0001] This application belongs to the field of industrial automation control technology, specifically relating to an energy storage device and control method for a large servo press. Background Technology

[0002] Large servo presses are gradually replacing traditional mechanical presses and are widely used in industrial fields. They exhibit unique power characteristics during operation: the downward pressing of the slide requires enormous instantaneous peak power, while the servo motor generates a large amount of regenerative braking energy during deceleration, braking, and return phases. This high-frequency, high-power throughput condition poses challenges to the stability of the power supply system and equipment.

[0003] To address this issue, traditional solutions often employ flywheel energy storage systems. These systems use a storage motor to drive a flywheel, storing kinetic energy. This requires a dedicated frequency converter for motor speed control and a complex energy conversion control program. However, flywheel energy storage systems suffer from several drawbacks in actual operation: the storage motor is a rotating machine, resulting in severe bearing wear, requiring regular maintenance and lubrication, and leading to a high failure rate; the storage motor still needs to idle during press standby or mold changes, generating friction and no-load losses, as well as noise and heat, worsening the workshop environment; critically, limited by mechanical inertia and capacity constraints, its energy response has a second-level lag, failing to match the millisecond-level forming transients of the stamping slide. This causes a sharp drop in DC bus voltage during stamping, triggering flicker in the workshop power grid, interfering with the control accuracy of the main servo motor, and affecting the stamping consistency of the products. Summary of the Invention

[0004] In a first aspect, embodiments of this application provide an energy storage device for a large servo press, comprising: Main servo drive system, supercapacitor energy storage module, pre-charge circuit control module, stamping working circuit module, CMS monitoring system, and safety protection module; The AC power output of the external power grid is connected to the input of the main servo drive system and the power input of the pre-charge circuit control module, respectively. The main servo drive system is electrically connected to the input of the stamping working circuit module via a DC bus. The output of the pre-charge circuit control module is connected to the input of the supercapacitor energy storage module. The output of the supercapacitor energy storage module is connected to the safety protection module. The CMS monitoring system is communicatively connected to both the main servo drive system and the pre-charge circuit control module.

[0005] Furthermore, the main servo drive system includes a rectifier unit, an inverter unit, and at least one main motor; the input terminal of the rectifier unit is connected to an external power grid, the output terminal of the rectifier unit is connected to a DC bus, the input terminal of the inverter unit is electrically connected to the DC bus, and the output terminal of the inverter unit is connected to the main motor; The pre-charge circuit control module includes a pre-charge contactor, a start-up buffer current-limiting resistor R1, and a bidirectional AC-DC rectifier; the pre-charge contactor, the bidirectional AC-DC rectifier, and the start-up buffer current-limiting resistor R1 are connected in series in sequence, the input terminal of the pre-charge contactor is connected to the external power grid, and the start-up buffer current-limiting resistor is connected to the input terminal of the supercapacitor energy storage module. The stamping working circuit module includes: a bypass contactor; the bypass contactor is connected between the DC bus and the input terminal of the supercapacitor energy storage module; The safety protection module includes: a discharge contactor K3 and a discharge resistor R2. The output terminal of the supercapacitor is connected to the discharge contactor K3. The discharge contactor K3 and the discharge resistor R2 are connected in series, and the outer casing of the discharge resistor R2 is grounded. The supercapacitor energy storage module includes a supercapacitor cell with a capacity of farad level and a reverse protection diode connected in series and parallel. The input terminal of the supercapacitor energy storage module is connected to the external power grid through a pre-charge circuit control module, and the output terminal is connected to the ground terminal through a safety protection module. The reverse protection diode is set in the equalization circuit between the supercapacitor cells connected in series and parallel, and its conduction direction is from the equalization resistor to the supercapacitor cell. It is used to block the reverse discharge current of the supercapacitor cell through the equalization resistor after the equalization is completed. The CMS monitoring system typically runs on an industrial control computer or a host PC. It collects voltage and current data of the supercapacitor energy storage module in real time via a CAN bus or RS485 communication interface, analyzes the current circuit operating status, and controls the pre-charging contactor and bypass contactor.

[0006] Secondly, embodiments of this application also provide a method for controlling the energy storage device of a large servo press, comprising the following steps: S1. When the main servo drive system is powered on, the voltage at the supercapacitor terminal is 0V, and the supercapacitor energy storage module is pre-charged with current limiting. After the supercapacitor terminal voltage reaches the preset safety benchmark value, the pre-charging is completed, and the main servo drive system enters standby mode. S2. The main servo drive system enters the stamping operation: When the main motor slider decelerates, brakes, or returns, the braking energy is fed back to the DC bus. When the DC bus voltage is higher than the supercapacitor terminal voltage, the supercapacitor energy storage module is charged. When the main motor slider descends to enter the forming mode, the DC bus voltage drops. When the DC bus voltage is lower than the supercapacitor terminal voltage, the supercapacitor energy storage module discharges to the DC bus and supplies power to the main motor together with the rectifier unit. During the stamping operation of the main servo drive system, the charging and discharging of the supercapacitor energy storage module is continuously and alternately executed. The charging and discharging switching is automatically realized based on the voltage comparison results between the DC bus voltage and the supercapacitor terminal voltage detected by the CMS monitoring system.

[0007] Furthermore, the specific steps of step S1 are as follows: S11. The main servo drive system is powered on, and the CMS monitoring system controls the pre-charge contactor to close and the bypass contactor to open. S12. The external power grid precharges the supercapacitor energy storage module through the start-up buffer current-limiting resistor in the pre-charging circuit; The S13.CMS monitoring system detects the voltage at the supercapacitor terminals in real time and determines whether it has reached the preset safety benchmark value. If so, it controls the pre-charge contactor to open and the bypass contactor to close, and the main servo drive system enters standby mode.

[0008] Furthermore, in step S2, when the main servo drive system enters the stamping operation, the CMS monitoring system controls the bypass contactor to remain closed.

[0009] Further, in step S2, when the main motor slider decelerates, brakes, or returns, the braking energy is fed back to the DC bus. When the DC bus voltage is higher than the supercapacitor terminal voltage, the supercapacitor energy storage module is charged, specifically including: The S21.CMS monitoring system collects the DC bus voltage Vbus and the supercapacitor terminal voltage Vsc in real time, where Vbus is the instantaneous value of the DC bus voltage and Vsc is the instantaneous value of the voltage of the supercapacitor energy storage module; the CMS monitoring system determines whether Vbus is greater than Vsc. S22. When Vbus>Vsc, the braking energy is fed back to the DC bus, and then flows into the supercapacitor energy storage module for charging through the circuit connected when the bypass contactor is closed.

[0010] Furthermore, in step S22, the CMS monitoring system also monitors Vbus in real time. When Vbus rises to a preset safety limit, the servo driver automatically alarms and stops.

[0011] Further, in step S2, when the main motor slider descends to enter the forming condition, the DC bus voltage drops. When the DC bus voltage is lower than the supercapacitor terminal voltage, the supercapacitor energy storage module discharges to the DC bus, jointly supplying power to the main motor with the rectifier unit. Specifically, this includes: The S23.CMS monitoring system collects the DC bus voltage Vbus and the supercapacitor terminal voltage Vsc in real time, where Vbus is the instantaneous value of the DC bus voltage and Vsc is the instantaneous value of the voltage of the supercapacitor energy storage module; the CMS monitoring system determines whether Vbus is less than Vsc. S24. When Vsc > Vbus, the supercapacitor energy storage module discharges to the DC bus through the circuit connected when the bypass contactor is closed.

[0012] Furthermore, in step S23, the CMS monitoring system monitors Vbus and Vsc in real time. When Vbus rises to a level greater than or equal to Vsc, the supercapacitor energy storage module stops discharging to the DC bus. When Vbus falls below Vsc again, the supercapacitor energy storage module resumes discharging to the DC bus. The stopping and re-discharging are automatically implemented based on the real-time voltage comparison between Vbus and Vsc.

[0013] Furthermore, an initialization step is included before step S1: The CMS monitoring system performs a power-on self-test to check whether the communication links with the supercapacitor energy storage module and the DC bus are normal. The CMS monitoring system reads the initial voltage and current data of the supercapacitor energy storage module to determine whether there are overvoltage, overcurrent, or undervoltage abnormalities. If an abnormality is detected, the CMS monitoring system will issue an alarm signal and prevent the main servo drive system from powering on; if the abnormality is detected, the CMS monitoring system will allow the main servo drive system to execute step S1.

[0014] As can be seen from the above technical solutions, this application has the following advantages: The energy storage device and control method for the large servo press provided in this application use a supercapacitor energy storage module composed of supercapacitor cells connected in series and parallel as the energy storage element. The controllable connection with the DC bus is achieved through the pre-charging circuit and the stamping working circuit. At the same time, the CMS monitoring system is used to collect the voltage and current data of the supercapacitor in real time and perform passive balancing and protection control. The high-speed rotating energy storage motor and its dedicated speed driver in the traditional solution are eliminated, so that the system is transformed from "mechanical motion" to "electrical stillness", realizing zero wear, zero noise, and zero no-load loss, reducing maintenance costs and on-site maintenance time. The CMS monitoring system collects the bus voltage Vbus and the supercapacitor voltage Vsc in real time, and controls the switching of the contactor based on the real-time voltage comparison results of Vbus and Vsc. Since this scheme uses the physical potential difference between Vbus and Vsc as the intrinsic driving force for energy flow, the direction of the charging and discharging current does not require complex current inner loop PI calculation, which simplifies the algorithm structure of the control software and reduces the software development difficulty and debugging threshold of the servo driver. At the same time, by directly switching through the contactor, the switching losses and EMI interference problems caused by high-frequency PWM rectification under high voltage and high power are avoided, and the operational reliability of the system under low-frequency heavy load conditions is improved. The pre-charging circuit control module, stamping working circuit module, safety protection module, and CMS monitoring system work together to achieve power-on current-limited pre-charging, braking energy recovery, forming power compensation, and residual energy discharge protection. Under the control of the CMS monitoring system, the pre-charging contactor, bidirectional AC-DC rectifier, and start-up buffer current-limiting resistor provide current-limited pre-charging to the supercapacitor energy storage module, preventing power-on surge impact. After pre-charging, the system automatically switches between charging and discharging based on the real-time comparison between the DC bus voltage Vbus and the supercapacitor terminal voltage Vsc, achieving braking energy recovery and instantaneous power compensation under forming conditions. The safety protection module releases the remaining energy of the supercapacitor through the discharge contactor and discharge resistor. The anti-reverse diode in the equalization circuit blocks the reverse discharge current of the supercapacitor cells through the equalization resistor after equalization, preventing abnormal mutual charging between cells. By using a supercapacitor energy storage module to absorb braking energy during slider deceleration and release energy during forming, and co-powering the rectifier unit, the drastic fluctuations in DC bus voltage are suppressed. During high-speed continuous stamping, the load power switches frequently. Without a rapid response buffer, the bus voltage will drop or surge significantly, triggering an alarm and shutdown of the driver. This voltage disturbance is coupled to the motor torque loop, causing torque pulsation and speed fluctuations, resulting in surface rippling or dimensional deviations in the stamped parts. By utilizing the supercapacitor's farad capacity and low internal resistance, a large current is released in milliseconds when the bus voltage drops, filling the power gap and stabilizing the bus voltage within the allowable fluctuation range. Stable bus voltage ensures the control accuracy of the motor current loop and speed loop, allowing the output torque and slider displacement to strictly follow the command values. This improves the dimensional consistency, contour accuracy, and surface quality of the stamped parts, providing reliable support for enterprises to improve yield and reduce scrap rates. Attached Figure Description

[0015] To more clearly illustrate the technical solution of this application, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a flowchart of a method for energy storage control of a large servo press according to the present invention.

[0017] Figure 2 This is a schematic diagram of the energy storage device for a large servo press according to the present invention.

[0018] Figure 3 This is a schematic diagram of the energy flow of the servo press of the present invention.

[0019] Among them, 1-external power grid, 2-rectifier unit, 3-DC bus, 4-inverter unit, 5-main motor, 6-supercapacitor energy storage module, 7-pre-charge contactor, 8-bypass contactor, 9-bidirectional AC-DC rectifier. Detailed Implementation

[0020] The various embodiments of this disclosure will be described more fully in the following detailed description of the specific steps of a control method for an energy storage device of a large servo press. This disclosure may have various embodiments, and adjustments and changes may be made therein. However, it should be understood that there is no intention to limit the various embodiments of this disclosure to the specific embodiments disclosed herein, but rather this disclosure should be understood to cover all adjustments, equivalents, and / or alternatives falling within the spirit and scope of the various embodiments of this disclosure.

[0021] This embodiment provides a control method for the energy storage device of a large servo press. Its core lies in replacing flywheel energy storage with a supercapacitor energy storage module. The CMS monitoring system periodically collects the bus voltage Vbus and the capacitor terminal voltage Vsc, comparing the difference to control charging and discharging switching. During slide deceleration / braking / return, Vbus rises above Vsc, and the CMS controls the bypass contactor to remain closed, feeding back energy to charge the capacitor. This eliminates the need for complex PI regulation; the response depends on the contactor's action and the circuit time constant, quickly absorbing shocks and suppressing bus overvoltage. During slide descent for forming, a large load causes Vbus to fall below Vsc, and the capacitor discharges to the bus, compensating for the power shortfall together with the rectifier unit and suppressing voltage drops. The entire switching is based on voltage comparison, eliminating the need for complex current loop debugging and simplifying the software. Compared to flywheel energy storage, it eliminates the delay, wear, and no-load losses caused by rotational inertia. Static energy storage stabilizes the bus voltage, ensuring the accuracy of motor torque and speed control, improving the quality of stamped parts, and reducing maintenance and debugging costs.

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Please see Figure 1 The diagram shows a flowchart of a control method for an energy storage device of a large servo press in a specific embodiment. The method includes the following steps: S1. When the main servo drive system is powered on, the voltage at the supercapacitor terminal is 0V, and the supercapacitor energy storage module is pre-charged with current limiting. After the supercapacitor terminal voltage reaches the preset safety benchmark value, the pre-charging is completed, and the main servo drive system enters standby mode. It should be noted that the current-limiting pre-charging mechanism, which safely raises the supercapacitor from zero voltage to a preset safety reference value during the initial power-on phase, has multiple key benefits. Firstly, current-limiting charging effectively suppresses the surge current impact on the supercapacitor at the moment of power-on, preventing excessive internal temperature rise or dielectric breakdown due to excessive charging current. It also protects the rectifier unit and DC bus from current spike damage, improving system power-on safety and device lifespan. Secondly, pre-charging the supercapacitor to a safe reference voltage ensures its immediate discharge capability during subsequent stamping operations, preventing delayed discharge response or insufficient energy output due to low voltage. This ensures the dynamic auxiliary power supply effect of the main motor under forming conditions. Furthermore, after pre-charging, the system automatically enters standby mode, providing clear operating condition switching boundaries, simplifying control logic, improving the overall automation level and startup reliability, and laying a stable initial voltage foundation for subsequent high-frequency charge-discharge cycles. S2. The main servo drive system enters the stamping operation: When the main motor slider decelerates, brakes, or returns, the braking energy is fed back to the DC bus. When the DC bus voltage is higher than the supercapacitor terminal voltage, the supercapacitor energy storage module is charged. When the main motor slider descends to enter the forming mode, the DC bus voltage drops. When the DC bus voltage is lower than the supercapacitor terminal voltage, the supercapacitor energy storage module discharges to the DC bus and supplies power to the main motor together with the rectifier unit. It should be noted that the real-time comparison of Vbus and Vsc by the CMS monitoring system to automatically switch charging and discharging states has multiple benefits. On the one hand, during the slider deceleration and return phases, braking energy can be instantly recovered and stored in the supercapacitor, eliminating the resistance heat loss under traditional energy-consuming braking methods and reducing overall power consumption and carbon emissions. On the other hand, under heavy-load forming conditions, the supercapacitor rapidly releases energy to assist in power supply, smoothing out bus voltage drops and playing a "peak shaving and valley filling" role, thereby reducing the instantaneous impact on the power grid and the demand on the rectifier unit's capacity margin. At the same time, the instantaneous switching control based on voltage comparison has a sensitive response and can dynamically maintain the stability of the DC bus voltage, ensuring the speed regulation accuracy of the main motor and the accuracy of the stamping position. In addition, the power buffering effect of the supercapacitor suppresses current spikes in the drive system, which helps protect the IGBT power module and rectifier unit, extends the service life of key components, and enhances the system's operational reliability and safety margin under frequent start-stop conditions. During the stamping operation of the main servo drive system, the charging and discharging of the supercapacitor energy storage module is continuously and alternately executed. The charging and discharging switching is automatically realized based on the voltage comparison results between the DC bus voltage and the supercapacitor terminal voltage detected by the CMS monitoring system.

[0024] This embodiment utilizes the physical potential difference between the bus voltage and the capacitor terminal voltage to automatically control the switching between charging and discharging, thereby achieving efficient recovery of braking energy and instantaneous power compensation during forming, stabilizing the bus voltage, and improving stamping accuracy.

[0025] In one embodiment of the present invention, based on step S1, the following will provide a possible embodiment and describe its specific implementation in a non-limiting manner.

[0026] S1. When the main servo drive system is powered on, the voltage at the supercapacitor terminal is 0V, and the supercapacitor energy storage module is pre-charged with current limiting. After the supercapacitor terminal voltage reaches the preset safety benchmark value, the pre-charging is completed, and the main servo drive system enters standby mode. An initialization step is included before step S1: The CMS monitoring system performs a power-on self-test to check whether the communication links with the supercapacitor energy storage module and the DC bus are normal. The CMS monitoring system reads the initial voltage and current data of the supercapacitor energy storage module to determine whether there are overvoltage, overcurrent, or undervoltage abnormalities. If an abnormality is detected, the CMS monitoring system will issue an alarm signal and prevent the main servo drive system from powering on; if the abnormality is detected, the CMS monitoring system will allow the main servo drive system to execute step S1. The specific steps of step S1 are as follows: S11. The main servo drive system is powered on, and the CMS monitoring system controls the pre-charge contactor to close and the bypass contactor to open. S12. The external power grid precharges the supercapacitor energy storage module through the start-up buffer current-limiting resistor in the pre-charging circuit; The S13.CMS monitoring system detects the voltage at the supercapacitor terminals in real time and determines whether it has reached the preset safety benchmark value. If so, it controls the pre-charge contactor to open and the bypass contactor to close, and the main servo drive system enters standby mode.

[0027] For example, a servo press has a preset safety reference value of 650V. After the external power grid supplies power, the rectifier unit first establishes the DC bus voltage to 650V. At this time, the pre-charge contactor closes, and electrical energy safely and slowly charges the supercapacitor energy storage module through the start-up buffer current-limiting resistor R1 and the bidirectional AC-DC rectifier. When the CMS monitoring system detects that the supercapacitor terminal voltage Vsc reaches 650V, it immediately disconnects the pre-charge contactor and closes the bypass contactor, short-circuits the current-limiting resistor, and enters standby mode. This avoids the large current surge at the moment of power-on and ensures that the capacitor terminal voltage is consistent with the bus voltage, establishing a reference for subsequent charging and discharging switching.

[0028] In one embodiment of the present invention, based on step S2, the following will provide a possible embodiment and describe its specific implementation in a non-limiting manner.

[0029] S2. The main servo drive system enters the stamping operation: When the main motor slider decelerates, brakes, or returns, the braking energy is fed back to the DC bus. When the DC bus voltage is higher than the supercapacitor terminal voltage, the supercapacitor energy storage module is charged. When the main motor slider descends to enter the forming mode, the DC bus voltage drops. When the DC bus voltage is lower than the supercapacitor terminal voltage, the supercapacitor energy storage module discharges to the DC bus and supplies power to the main motor together with the rectifier unit. When the main motor slider decelerates, brakes, or returns, the braking energy is fed back to the DC bus. When the DC bus voltage is higher than the supercapacitor terminal voltage, the supercapacitor energy storage module is charged, specifically including: The S21.CMS monitoring system collects the DC bus voltage Vbus and the supercapacitor terminal voltage Vsc in real time, where Vbus is the instantaneous value of the DC bus voltage and Vsc is the instantaneous value of the voltage of the supercapacitor energy storage module; the CMS monitoring system determines whether Vbus is greater than Vsc. S22. When Vbus>Vsc, the braking energy is fed back to the DC bus, and then flows into the supercapacitor energy storage module for charging through the circuit connected when the bypass contactor is closed. In step S22, the CMS monitoring system also monitors Vbus in real time. When Vbus rises to the preset safety limit, the servo drive automatically alarms and stops.

[0030] For example, during press operation, the bypass contactor remains closed. When the slider decelerates upwards during the return stroke, the main servo motor switches to generator mode due to mechanical inertia. Braking energy is fed into the DC bus through the inverter unit, and the bus voltage Vbus instantly surges from 650V to 710V. The CMS monitoring system compares Vbus and Vsc in real time. Since Vsc is still 650V, it determines that Vbus > Vsc, and electrical energy passively flows into the supercapacitor module for charging. This charging process is automatically completed within milliseconds using the physical potential difference, without the need for software calculation, successfully clamping the bus voltage within the safe upper limit of 800V. At the same time, the CMS continuously monitors Vbus. When the bus voltage rises to the preset safe upper limit of 800V due to continuous feedback, the servo drive automatically alarms and stops to prevent overvoltage. When the main motor slider descends to enter the forming mode, the DC bus voltage drops. When the DC bus voltage is lower than the supercapacitor terminal voltage, the supercapacitor energy storage module discharges to the DC bus, jointly supplying power to the main motor with the rectifier unit. Specifically, this includes: The S23.CMS monitoring system collects the DC bus voltage Vbus and the supercapacitor terminal voltage Vsc in real time, where Vbus is the instantaneous value of the DC bus voltage and Vsc is the instantaneous value of the voltage of the supercapacitor energy storage module; the CMS monitoring system determines whether Vbus is less than Vsc. S24. When Vsc > Vbus, the supercapacitor energy storage module discharges to the DC bus through the circuit connected when the bypass contactor is closed. In step S23, the CMS monitoring system monitors Vbus and Vsc in real time. When Vbus rises to a level greater than or equal to Vsc, the supercapacitor energy storage module stops discharging to the DC bus. When Vbus falls below Vsc again, the supercapacitor energy storage module resumes discharging to the DC bus. The stopping and re-discharging are automatically implemented based on the real-time voltage comparison between Vbus and Vsc.

[0031] For example, when the slider descends to the bottom dead center for intense pressing, the main servo motor draws a large current instantaneously, causing the DC bus voltage to drop rapidly to 600V due to grid power supply limitations. At this time, the supercapacitor voltage has risen to 710V due to previous braking and recharging. The CMS monitoring system determines that Vsc > Vbus, and the supercapacitor module releases a large instantaneous current to the DC bus within milliseconds, working with the rectifier unit to power the motor. This stabilizes the bus voltage drop above 650V, ensuring the control accuracy of the servo motor. When Vbus rises to near or equal to Vsc, the supercapacitor energy storage module naturally stops discharging to the DC bus. During the stamping process, the bypass contactor remains closed, and the charging and discharging of the supercapacitor is passively switched according to the real-time voltage difference between Vbus and Vsc. When Vbus is below 650V, the rectifier unit actively charges the DC bus, replenishing the bus voltage to 650V, thus completing the power compensation cycle.

[0032] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0033] like Figure 2 As shown, the following are embodiments of the energy storage device for a large servo press provided in this disclosure. This system and the control method for the energy storage device of the large servo press in the above embodiments belong to the same inventive concept. For details not described in detail in the embodiments of the energy storage device of the large servo press, please refer to the embodiments of the control method for the energy storage device of the large servo press.

[0034] The device includes: Main servo drive system, supercapacitor energy storage module 6, pre-charge circuit control module, stamping working circuit module, CMS monitoring system, safety protection module; The AC power output of the external power grid 1 is connected to the input of the main servo drive system and the power input of the pre-charge circuit control module, respectively; the main servo drive system is electrically connected to the input of the stamping working circuit module via the DC bus 3; the output of the pre-charge circuit control module is connected to the input of the supercapacitor energy storage module 6; the output of the supercapacitor energy storage module 6 is connected to the safety protection module; the CMS monitoring system is communicatively connected to both the main servo drive system and the pre-charge circuit control module. The main servo drive system, such as Figure 3 As shown, it includes a rectifier unit, an inverter unit, and at least one main motor; the input terminal of the rectifier unit 2 is connected to the external power grid, the output terminal of the rectifier unit 2 is connected to the DC bus 3, the input terminal of the inverter unit 4 is electrically connected to the DC bus 3, and the output terminal of the inverter unit 4 is connected to the main motor 5; The pre-charge circuit control module includes a pre-charge contactor 7, a start-up buffer current-limiting resistor R1, and a bidirectional AC-DC rectifier 9. The pre-charge contactor 7, the bidirectional AC-DC rectifier 9, and the start-up buffer current-limiting resistor R1 are connected in series. The input terminal of the pre-charge contactor 7 is connected to the external power grid 1, and the start-up buffer current-limiting resistor is connected to the input terminal of the supercapacitor energy storage module 6. The stamping working circuit module includes: a bypass contactor 8; the bypass contactor 8 is connected between the DC bus 3 and the input terminal of the supercapacitor energy storage module 6; The safety protection module includes: a discharge contactor K3 and a discharge resistor R2. The output terminal of the supercapacitor energy storage module 6 is connected to the discharge contactor K3. The discharge contactor K3 and the discharge resistor R2 are connected in series, and the outer casing of the discharge resistor R2 is grounded. The supercapacitor energy storage module 6 includes a supercapacitor cell with a capacity of farad level and a reverse protection diode connected in series and parallel. The input terminal of the supercapacitor energy storage module 6 is connected to the external power grid 1 through a pre-charge circuit control module, and the output terminal is connected to the ground terminal through a safety protection module. The reverse protection diode is set in the equalization circuit between the supercapacitor cells connected in series and parallel, and its conduction direction is from the equalization resistor to the supercapacitor cell. It is used to block the reverse discharge current of the supercapacitor cell through the equalization resistor after the equalization is completed. The CMS monitoring system typically runs on an industrial control computer or a host PC. It collects voltage and current data of the supercapacitor energy storage module in real time via a CAN bus or RS485 communication interface, analyzes the current circuit operating status, and controls the pre-charging contactor and bypass contactor. This embodiment constructs a complete and reliable large-scale servo press energy storage system through the coordinated operation of the aforementioned modules. Specifically, the pre-charge circuit control module performs current-limited pre-charge of the supercapacitor energy storage module during the initial power-on phase via a pre-charge contactor, buffer current-limiting resistor, and bidirectional AC-DC rectifier to suppress surge current impact and ensure power-on safety. The stamping working circuit module establishes a rapid charging and discharging path between the DC bus and the supercapacitor through a bypass contactor. Combined with the CMS monitoring system's automatic switching based on the real-time comparison results of Vbus and Vsc, it achieves efficient recovery of braking energy and power auxiliary supply during forming operations, reducing peak grid load and improving energy utilization efficiency. The anti-reverse diodes installed inside the supercapacitor energy storage module can block the reverse discharge current of the balancing resistor, preventing abnormal mutual charging between individual capacitors and enhancing the module's self-protection capability. The safety protection module releases redundant energy in a timely manner through a discharge contactor and discharge resistor to prevent overvoltage hazards. Overall, this device combines startup safety, operational efficiency, intelligent control, and reliable fault protection, making it particularly suitable for long-term stable operation under high-frequency, heavy-load stamping conditions.

[0035] Example 1, taking the energy storage device of a large servo press with a capacity of 2500 tons as an example, details the implementation process of the control method of this application.

[0036] This embodiment eliminates the energy storage motor and its dedicated 500kW speed-regulating inverter cabinet used in traditional industry designs to provide flywheel kinetic energy. Instead, it directly connects to a completely electrically static, farad-level supercapacitor energy storage module 6 with a rated operating voltage of 800V. The input terminal of the supercapacitor energy storage module 6 is connected to the external power grid 1 through a pre-charge circuit control module, and the output terminal is connected to the ground terminal through a safety protection module. In the pre-charge circuit control module, the pre-charge contactor 7, the bidirectional AC-DC rectifier 9, and the start-up buffer current-limiting resistor R1 are connected in series. In the stamping working circuit module, the bypass contactor 8 is connected between the DC bus 3 and the input terminal of the supercapacitor energy storage module 6, and the bypass contactor 8 is connected in parallel with the pre-charge circuit.

[0037] The specific execution process of step S1 is as follows: After the CMS monitoring system completes its power-on self-test, the main control PLC does not need to run complex inverter speed calculations or magnetic field orientation algorithms. After the external power grid 1 is powered on, the rectifier unit 2 establishes the DC bus 3 voltage to a constant 650V; at this time, the bypass contactor 8 is in the open state, and the CMS monitoring system controls the pre-charging contactor 7 to close. Electrical energy is safely and slowly pre-charged to the supercapacitor energy storage module 6 through the pre-charging contactor 7, the bidirectional AC-DC rectifier 9, and the start-up buffer current-limiting resistor R1; the CMS monitoring system monitors the supercapacitor terminal voltage Vsc in real time. When Vsc reaches the preset safety benchmark value of 650V, the CMS controls the pre-charging contactor 7 to open and simultaneously controls the bypass contactor 8 to close, and the main servo drive system enters standby mode.

[0038] The specific execution process of step S2 is as follows: The slider decelerates upwards during the return stroke, and the four main motors 5 change to generator mode due to mechanical inertia. The braking energy is fed back into the DC bus 3 through the inverter unit 4. At this time, the DC bus voltage Vbus instantly surges from 650V to 710V. The CMS monitoring system collects the DC bus voltage Vbus and the supercapacitor terminal voltage Vsc in real time, where Vbus is the instantaneous value of the DC bus voltage and Vsc is the instantaneous value of the voltage of the supercapacitor energy storage module. The CMS monitoring system determines whether Vbus is greater than Vsc. When it is determined that Vbus=710V>Vsc=650V, the braking energy is fed back to the DC bus and flows into the supercapacitor energy storage module 6 for charging through the charging circuit formed by the closed bypass contactor 8. This charging process uses the physical voltage difference to quickly absorb the instantaneous braking energy within milliseconds, successfully forcibly suppressing the DC bus voltage to within the safe upper limit of 800V, avoiding the burnout of traditional resistors and bus overvoltage alarms. The CMS monitoring system also monitors Vbus in real time. When Vbus rises to the preset safety limit of 800V, the servo drive will automatically alarm and stop.

[0039] The slider applies millisecond-level intense pressure at the bottom dead center, and the four main motors 5 instantly draw current away. Due to the limited power supply capacity of the external power grid, the voltage of the DC bus 3 drops rapidly. The CMS monitoring system collects the DC bus voltage Vbus and the supercapacitor terminal voltage Vsc in real time, where Vbus is the instantaneous value of the DC bus voltage and Vsc is the instantaneous value of the supercapacitor energy storage module voltage. The CMS monitoring system determines whether Vbus is less than Vsc. When the bus voltage Vbus drops to 600V, the supercapacitor terminal voltage has already been charged to Vsc=710V in the previous stage. The CMS monitoring system determines that Vsc>Vbus, and the supercapacitor energy storage module 6 releases a large instantaneous current to the DC bus 3 through the circuit connected when the bypass contactor 8 is closed. The rectifier unit 2 and the supercapacitor energy storage module jointly output power to stabilize the DC bus voltage drop above 650V, eliminating the violent voltage flicker caused by the inertial lag of the mechanical motors, and providing stable voltage support for the main motors 5. As a result, the consistency accuracy and surface roughness quality of the product stamping and forming process are improved. The CMS monitoring system monitors Vbus in real time. When Vbus rises to near or equal to Vsc, the supercapacitor energy storage module naturally stops discharging to the DC bus. During the stamping process, the bypass contactor remains closed, and the charging and discharging of the supercapacitor is passively switched according to the real-time voltage difference between Vbus and Vsc. When Vbus is below 650V, the rectifier unit actively charges the DC bus to replenish the bus voltage to 650V, completing the power compensation cycle.

[0040] In addition, traditional energy storage motors still need to run continuously and consume electrical energy to maintain the speed. However, in this embodiment, the supercapacitor energy storage module 6 is in a completely electrically static state, with no speed control driver running and no calculation program refresh in the main control PLC. The field presents a state of zero noise, zero temperature rise, and zero power consumption, and the no-load power loss is completely reduced to zero.

[0041] This embodiment uses a 2500-ton servo press as an example to verify the actual effect of the energy storage device. By eliminating the traditional 500kW energy storage motor and dedicated frequency converter cabinet, a fully electrically static supercapacitor module is directly mounted on the DC bus. The main control PLC does not need to run any frequency conversion speed regulation algorithm, eliminating bearing wear and no-load losses caused by mechanical rotation. During operation, when the slider returns to braking, the CMS monitoring system compares Vbus and Vsc in real time. When Vbus > Vsc, the feedback energy is directly charged into the supercapacitor through the bypass contactor 8, forcibly suppressing the bus voltage of 710V to within the safe upper limit of 800V, avoiding resistor burnout. When the slider descends to press, the CMS monitoring system compares Vbus and Vsc in real time. When Vsc > Vbus, the supercapacitor releases a large current in milliseconds at the instant the bus voltage drops to 600V, working with the rectifier unit to make the bus voltage rise and stabilize above 650V, eliminating the interference of voltage flicker on the main servo motor and improving the dimensional consistency and surface quality of the stamped parts. Throughout the entire process, the supercapacitor remains electrically stationary, operating without a speed controller, achieving standby operation with zero noise, zero temperature rise, and zero power consumption, and reducing no-load loss to zero.

[0042] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0043] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of devices, methods, and computer program products according to various embodiments of the present disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in a block diagram and / or flowchart, and combinations of blocks in block diagrams and / or flowcharts, may be implemented using a dedicated hardware-based system that performs the specified function or operation, or using a combination of dedicated hardware and computer instructions.

[0044] In the embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. For instance, the division of 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 system, or some features may be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, or it may be an electrical, mechanical, or other form of connection.

[0045] Furthermore, the described features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Numerous specific details are provided in the following description to give a full understanding of embodiments of the invention. However, those skilled in the art will recognize that the technical solutions of the invention can be practiced without one or more of the specific details, or other methods, components, apparatuses, steps, etc., can be employed. In other instances, well-known methods, apparatuses, implementations, or operations are not shown or described in detail to avoid obscuring various aspects of the invention.

[0046] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An energy storage device for a large servo press, characterized in that, include: Main servo drive system, supercapacitor energy storage module, pre-charge circuit control module, stamping working circuit module, CMS monitoring system, and safety protection module; The AC power output of the external power grid is connected to the input of the main servo drive system and the power input of the pre-charge circuit control module, respectively. The main servo drive system is electrically connected to the input of the stamping working circuit module via a DC bus. The output of the pre-charge circuit control module is connected to the input of the supercapacitor energy storage module. The output of the supercapacitor energy storage module is connected to the safety protection module. The CMS monitoring system is communicatively connected to both the main servo drive system and the pre-charge circuit control module.

2. The energy storage device for a large servo press according to claim 1, characterized in that, The main servo drive system includes a rectifier unit, an inverter unit, and at least one main motor; the input terminal of the rectifier unit is connected to an external power grid, the output terminal of the rectifier unit is connected to a DC bus, the input terminal of the inverter unit is electrically connected to the DC bus, and the output terminal of the inverter unit is connected to the main motor. The pre-charge circuit control module includes a pre-charge contactor, a start-up buffer current-limiting resistor, and a bidirectional AC-DC rectifier; the pre-charge contactor, the bidirectional AC-DC rectifier, and the start-up buffer current-limiting resistor are connected in series in sequence, the input terminal of the pre-charge contactor is connected to the external power grid, and the start-up buffer current-limiting resistor is connected to the input terminal of the supercapacitor energy storage module. The stamping working circuit module includes: a bypass contactor; the bypass contactor is connected between the DC bus and the input terminal of the supercapacitor energy storage module; The safety protection module includes: a discharge contactor and a discharge resistor; the output terminal of the supercapacitor is connected to the discharge contactor, the discharge contactor and the discharge resistor are connected in series, and the casing of the discharge resistor is grounded; The supercapacitor energy storage module includes a supercapacitor cell with a capacity of farad level and a reverse protection diode connected in series and parallel. The input end of the supercapacitor energy storage module is connected to the external power grid through a pre-charge circuit control module, and the output end is connected to the grounding end through a safety protection module. The reverse protection diode is set in the equalization circuit between the supercapacitor cells connected in series and parallel, and its conduction direction is from the equalization resistor to the supercapacitor cell. The CMS monitoring system runs on an industrial control computer or a host PC. It collects voltage and current data of the supercapacitor energy storage module in real time through a CAN bus or RS485 communication interface, analyzes the current circuit operating status, and controls the pre-charging contactor and bypass contactor.

3. A control method for an energy storage device of a large servo press, characterized in that, The method is implemented using the energy storage device of the large servo press as described in any one of claims 1 to 2; The method includes the following steps: S1. When the main servo drive system is powered on, the voltage at the supercapacitor terminal is 0V, and the supercapacitor energy storage module is pre-charged with current limiting. After the supercapacitor terminal voltage reaches the preset safety benchmark value, the pre-charging is completed, and the main servo drive system enters standby mode. S2. The main servo drive system enters the stamping operation: When the main motor slider decelerates, brakes, or returns, the braking energy is fed back to the DC bus. When the DC bus voltage is higher than the supercapacitor terminal voltage, the supercapacitor energy storage module is charged. When the main motor slider descends to enter the forming mode, the DC bus voltage drops. When the DC bus voltage is lower than the supercapacitor terminal voltage, the supercapacitor energy storage module discharges to the DC bus and supplies power to the main motor together with the rectifier unit. During the stamping operation of the main servo drive system, the charging and discharging of the supercapacitor energy storage module is continuously and alternately executed. The charging and discharging switching is automatically realized based on the voltage comparison results between the DC bus voltage and the supercapacitor terminal voltage detected by the CMS monitoring system.

4. The energy storage device control method for a large servo press according to claim 3, characterized in that, The specific steps of step S1 are as follows: S11. The main servo drive system is powered on, and the CMS monitoring system controls the pre-charge contactor to close and the bypass contactor to open. S12. The external power grid precharges the supercapacitor energy storage module through the start-up buffer current-limiting resistor in the pre-charging circuit; The S13.CMS monitoring system detects the voltage at the supercapacitor terminals in real time and determines whether it has reached the preset safety benchmark value. If so, it controls the pre-charge contactor to open and the bypass contactor to close, and the main servo drive system enters standby mode.

5. The energy storage device control method for a large servo press according to claim 3, characterized in that, In step S2, when the main servo drive system enters the stamping operation, the CMS monitoring system controls the bypass contactor to remain closed.

6. The energy storage device control method for a large servo press according to claim 3, characterized in that, In step S2, when the main motor slider decelerates, brakes, or returns, the braking energy is fed back to the DC bus. When the DC bus voltage is higher than the supercapacitor terminal voltage, the supercapacitor energy storage module is charged, specifically including: The S21.CMS monitoring system collects the DC bus voltage Vbus and the supercapacitor terminal voltage Vsc in real time, where Vbus is the instantaneous value of the DC bus voltage and Vsc is the instantaneous value of the voltage of the supercapacitor energy storage module; the CMS monitoring system determines whether Vbus is greater than Vsc. S22. When Vbus>Vsc, the braking energy is fed back to the DC bus, and then flows into the supercapacitor energy storage module for charging through the circuit connected when the bypass contactor is closed.

7. The energy storage device control method for a large servo press according to claim 6, characterized in that, In step S22, the CMS monitoring system also monitors Vbus in real time. When Vbus rises to the preset safety limit, the servo drive automatically alarms and stops.

8. The energy storage device control method for a large servo press according to claim 3, characterized in that, In step S2, when the main motor slider descends to enter the forming condition, the DC bus voltage drops. When the DC bus voltage is lower than the supercapacitor terminal voltage, the supercapacitor energy storage module discharges to the DC bus, jointly supplying power to the main motor with the rectifier unit. Specifically, this includes: The S23.CMS monitoring system collects the DC bus voltage Vbus and the supercapacitor terminal voltage Vsc in real time, where Vbus is the instantaneous value of the DC bus voltage and Vsc is the instantaneous value of the voltage of the supercapacitor energy storage module; the CMS monitoring system determines whether Vbus is less than Vsc. S24. When Vsc > Vbus, the supercapacitor energy storage module discharges to the DC bus through the circuit connected when the bypass contactor is closed.

9. The energy storage device control method for a large servo press according to claim 8, characterized in that, In step S23, the CMS monitoring system monitors Vbus and Vsc in real time. When Vbus rises to a level greater than or equal to Vsc, the supercapacitor energy storage module stops discharging to the DC bus. When Vbus falls below Vsc again, the supercapacitor energy storage module resumes discharging to the DC bus. The stopping and re-discharging are automatically implemented based on the real-time voltage comparison between Vbus and Vsc.

10. The energy storage device control method for a large servo press according to claim 3, characterized in that, An initialization step is included before step S1: The CMS monitoring system performs a power-on self-test to check whether the communication link with the supercapacitor energy storage module and the DC bus is normal. The CMS monitoring system reads the initial voltage and current data of the supercapacitor energy storage module to determine whether there are overvoltage, overcurrent, or undervoltage abnormalities. If any abnormality is detected, the CMS monitoring system will issue an alarm signal and prevent the main servo drive system from powering on. If all goes well, the CMS monitoring system allows the main servo drive system to execute step S1.

Images