Recycled energy measuring and calculating device and method based on elevator brake resistor loop current detection

Abstract

The invention discloses a regenerative energy measuring and calculating device and method based on elevator braking resistor loop current detection, the device is clamped on an elevator braking resistor loop wire through a toggle clip type current sensor, the braking current is sampled and subjected to event identification, the current is integrated during a braking event to obtain an accumulated electric charge quantity Q, and the accumulated electric charge quantity Q is calculated. And instantaneous power is calculated by combining a braking voltage parameter when needed and integration is carried out to obtain accumulated electric energy E. Wherein the braking voltage parameter can be a preset / user-input fixed value, or a real-time voltage Ub obtained through high-resistance partial voltage across the two ends of the braking resistor and isolation sampling. The device supports setting of a statistical time window, automatically stores, displays and inquires statistical results when expiration occurs, and realizes long-period on-site deployment by adopting a battery power supply and low-power-consumption strategy. According to the scheme, an elevator control system or a direct-current bus does not need to be connected, regenerated energy statistical data capable of being retested and reconciliated can be rapidly obtained, and the method is used for project establishment, model selection and acceptance assessment of energy storage and energy conservation transformation.

Description

Technical Field

[0001] This invention relates to the field of elevator energy-saving assessment and electricity metering technology, specifically to a device and method for calculating regenerative energy based on elevator braking resistor circuit current detection. Background Technology

[0002] During elevator operation, when in descending, decelerating, or ascending unloaded conditions, it enters regenerative braking mode. The regenerative energy generated during this process is conventionally dissipated as heat by activating the braking resistor in the braking unit, resulting in energy waste. In energy storage elevator retrofit projects, stakeholders such as owners, energy service companies, and equipment suppliers urgently need to clarify a core issue: what is the upper limit of regenerative energy that can be recovered under actual operating conditions? This data is crucial for project feasibility analysis, energy storage equipment selection and matching, and energy saving calculations upon project acceptance.

[0003] There are currently three main types of methods for calculating the regenerative energy of elevators: Theoretical estimation method: Based on the elevator's design parameters such as rated load, travel distance, and start / stop frequency, regenerative energy is calculated through mechanical formulas and operational logic. The drawback of this method is that it does not consider real-world operating conditions such as dynamic load changes and efficiency fluctuations during actual elevator operation. Therefore, the calculated results deviate significantly from the actual recoverable energy, limiting its reference value.

[0004] Inverter communication data acquisition method: By connecting to the internal communication interface of the elevator inverter, the regenerative energy data recorded during the inverter's operation is read. The problem with this method is its extremely poor compatibility. The communication protocols of inverters of different brands and models are not unified, and most manufacturers have not opened the relevant data interfaces. At the same time, it requires professional technicians to perform communication debugging, relies on manufacturer technical support, and lacks universality and convenience.

[0005] Adding measuring devices to the DC bus: Measuring equipment is connected in series or parallel on the DC bus side of the elevator to directly detect the bus current and voltage to calculate regenerative energy. This method requires modification of the elevator's original electrical circuit, making construction complex. Furthermore, it may interfere with the stability of the elevator control system during construction and operation, posing safety hazards. Additionally, the construction period is long, affecting the normal use of the elevator.

[0006] In summary, existing calculation methods generally suffer from poor adaptability, complex construction, reliance on manufacturer interfaces, interference with elevator operation, or unreliable calculation results. In particular, they struggle to obtain verifiable and reconcilable statistical data on regenerative energy without altering the elevator control system, connecting to the DC bus, or affecting normal elevator operation. Therefore, a dedicated portable calculation device is needed that can be directly applied to the elevator braking resistor circuit to accurately calculate regenerative energy parameters within a set time range, providing a reliable basis for assessing the energy-saving potential of energy storage projects. Summary of the Invention

[0007] The purpose of this invention is to provide a device and method for calculating regenerative energy based on the current detection of elevator braking resistor circuit, aiming to solve the difficulty of obtaining regenerative energy statistics data in the elevator field in a "non-invasive, repeatable, and reconcilable" manner.

[0008] This invention is implemented as follows: a regenerative energy calculation device based on elevator braking resistor circuit current detection, comprising: Clip-on current detection module, used to be clipped onto the elevator braking resistor circuit wire to obtain braking current signal; The metering processing module is used to sample and filter the braking current signal, and identify braking events based on current threshold and duration criteria. The integral calculation module is used to integrate the braking current during the braking event to obtain the cumulative charge Q, and to calculate the instantaneous power by combining the voltage parameters when selecting energy output and to integrate the cumulative electrical energy E. The statistical time window and sealing module is used to accumulate Q or E within a preset statistical time window and seal and store the accumulated amount and corresponding time information at the end of the time window; The device also includes a human-computer interaction and display module for setting and displaying the statistical time window, output unit, and operating status, and for querying archived records; the device further includes a battery-powered and low-power module for supporting long-term portable operation.

[0009] Preferably, the voltage parameter is a preset or user-input fixed voltage Uset, and the instantaneous power is calculated as P(t) = Uset·Ib(t).

[0010] Preferably, it also includes a voltage acquisition module, which is connected across the two ends of the braking resistor to obtain the braking voltage Ub(t) and performs isolated sampling, and the instantaneous power is calculated according to P(t)=Ub(t)·Ib(t).

[0011] Preferably, the output unit can be selected between Ah and Wh, and the sealed record is saved and displayed according to the selected unit.

[0012] Preferably, the statistical time window is a configurable duration range, preferably 0.5 days to 30 days.

[0013] Preferably, the sealed storage includes at least one of the following: cumulative amount, start and end time or duration of statistical time window, voltage mode information used, and verification information for reconciliation.

[0014] Preferably, the metering processing module allows the integral calculation module to perform integration only during the period when a braking event is detected, and exits the integration state after the braking event ends to reduce erroneous metering.

[0015] Preferably, the low-power module includes at least one of: deep sleep and RTC timed wake-up, sampling frequency switching triggered by braking event, and display energy-saving control.

[0016] The present invention also discloses a method for calculating the regenerative energy of an elevator using the aforementioned device, comprising: sampling the braking current and performing conversion; identifying braking events based on threshold and duration criteria; integrating the current during the braking event according to the sampling period to obtain the cumulative charge Q(Ah); when Wh output is selected, acquiring voltage parameters and calculating instantaneous power and integrating to obtain the cumulative electrical energy E(Wh); sealing the cumulative amount and corresponding time information at the end of the preset statistical time window and outputting and displaying it.

[0017] Preferably, the sealing step includes writing the data of this statistical time window into non-volatile storage, and setting the data to read-only display after sealing for use in acceptance and reconciliation.

[0018] Compared with the prior art, the beneficial effects of the present invention are: Non-intrusive deployment with high security: No need to connect to the elevator control system or modify the wiring of the DC bus or braking resistor circuit. Installation is achieved only through clip-on sensors and optional jumper probes. The installation process does not affect the normal operation of the elevator, avoids interference with the original electrical system of the elevator, and ensures the safety of elevator operation and the use of the device itself.

[0019] The calculation results are reproducible and reconcilable: It supports custom statistical time windows, and automatically seals complete statistical data upon expiration. The data is read-only and cannot be modified. Different times and different people use the device to calculate the same elevator, which can obtain consistent results, meet the reconciliation requirements of the project acceptance stage, and the data has high reliability.

[0020] Dual output modes adapt to various scenarios: It can output the cumulative charge Q, which is independent of voltage and can be used for relative comparison and trend analysis of the regenerative energy potential of elevators of different brands and models; it can also output the cumulative electrical energy E for accurate calculation of energy saving, adapting to the needs of different scenarios such as project initiation, equipment selection, acceptance and settlement of energy storage projects.

[0021] Highly adaptable and with adjustable measurement accuracy: The braking voltage supports two methods: fixed parameter input and real-time bridging measurement. The fixed parameter method is suitable for scenarios where there is no permission to obtain detailed parameters of the braking resistor, and the operation is convenient. The bridging measurement method can obtain dynamic voltage, improve the accuracy of power calculation, and users can flexibly choose according to actual needs to adapt to the braking system configuration of different elevators.

[0022] Excellent portability and support for long-term operation: Powered by a high-capacity lithium battery, and with low-power strategies such as deep sleep, sampling frequency switching, and display energy saving, a single charge can support up to 30 days of continuous statistics. The device is small in size and light in weight, making it easy to carry to multiple elevator sites for use and with high deployment efficiency. Attached Figure Description

[0023] Figure 1 This is a block diagram of the device structure of the present invention; Figure 2 This is an installation diagram of the present invention; Figure 3 This is a flowchart of the braking event identification and power / energy integration process of the present invention; Figure 4 This is a schematic diagram of the low-power state machine of the present invention; Detailed Implementation

[0024] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0025] The following description, in conjunction with the accompanying drawings and specific embodiments, provides further details: Example 1 like Figure 1-4 As shown, the specific hardware selection and composition of the device are as follows: In this embodiment, the specific selection and composition of each hardware module of the device are as follows to ensure the practicality, stability and accuracy of the device: Clip-on current sensor: A CR630 type Rogowski coil current sensor with a range of 0-50A, an output signal of 0-1V analog voltage, an accuracy class of 0.5, and an operating frequency range of 50Hz-1kHz is selected. It is adapted to the current characteristics of elevator braking resistor circuits, with a clamping diameter range of 5-20mm to meet the installation requirements of different wire specifications. It has good anti-electromagnetic interference capability and complies with the GB / T13850-1998 current transformer standard.

[0026] Signal conditioning / sampling circuit: Composed of a filter circuit, an operational amplifier circuit, and an A / D conversion circuit. The filter circuit uses a second-order RC low-pass filter circuit, with 1kΩ metal film resistors and 0.1μF ceramic capacitors, and a cutoff frequency of 1kHz, used to filter out high-frequency interference in the current sensor output signal; the operational amplifier circuit uses an AD8221 instrumentation amplifier with a gain of 5, amplifying the 0-1V signal to 0-5V to match the input range of the A / D conversion circuit; the A / D conversion circuit uses an ADS1115 analog-to-digital converter chip, with a sampling resolution of 16 bits and a maximum sampling rate of 860SPS, communicating with the MCU via an I2C interface to ensure sampling accuracy.

[0027] The metering processing unit (MCU) uses an STM32L476RGT6 microcontroller, based on the ARM Cortex-M4 core, with an operating frequency of 80MHz. It has 1MB Flash and 128KB RAM, supports low-power operation mode, and has rich peripheral interfaces to meet the functional requirements of signal sampling, data calculation, storage control, and human-machine interaction. It also has a built-in RTC clock module to achieve accurate time recording and timed wake-up.

[0028] Voltage parameter acquisition unit: 4A Fixed / Input Voltage Parameter Module: No additional hardware circuitry is required. The storage and retrieval of voltage parameters are achieved through the MCU's software program. The voltage values ​​input by the user are stored in the MCU's built-in Flash memory and are not lost when power is off.

[0029] 4b. The bridging voltage measurement module consists of a high-resistance voltage divider circuit and an isolated sampling circuit. The high-resistance voltage divider circuit uses two 1MΩ / 0.1% precision metal film resistors connected in series across the braking resistor to divide the voltage from a maximum of 500V to 0-2.5V. The isolated sampling circuit uses an ADUM1400 four-channel digital isolator and an ADS1115 analog-to-digital converter chip to achieve strong and weak current isolation (isolation voltage ≥2.5kV), ensuring sampling safety, and the sampling accuracy is consistent with that of current sampling.

[0030] Storage Unit: The W25Q64JVFIQ serial Flash memory chip is selected, with a capacity of 8MB, supporting SPI interface communication, erase and write life ≥100,000 times, and data retention time ≥20 years. It is used to store data such as current cumulative amount, historical sealed records, and user configuration parameters. It adopts a paging storage method, with each sealed record occupying an independent storage page, which is convenient for querying and management.

[0031] Display Unit and Key Input Unit: The display unit uses a 128x64 pixel LCD screen, supports Chinese and English display, has an operating current of ≤10mA, and uses LED backlight, which can be controlled by software. The key input unit uses 5 tactile buttons, which are defined as power button, setting button, confirmation button, up button and down button. The buttons are connected to the GPIO port of the MCU and are debouncing through software to avoid accidental triggering.

[0032] Battery and Power Management Unit: The battery pack uses a 3.7V / 5000mAh lithium polymer battery, supporting 5V / 1A charging; the power management unit uses a BQ24074 lithium battery charging management chip and an AMS1117-3.3V linear regulator chip. The BQ24074 realizes constant current and constant voltage charging of the battery and overcharge, over-discharge, and overcurrent protection, while the AMS1117-3.3V regulates the battery voltage to 3.3V to power each module; it also integrates a low battery detection circuit, which feeds back the battery voltage to the MCU's ADC interface through a voltage divider resistor to realize low battery monitoring.

[0033] Installation and parameter configuration of the device: Installation process: Preparation: Disconnect the elevator's main power supply, ensure there is no current in the braking resistor circuit, and ensure the safety of the installation personnel; check that the device is undamaged, the sensors and test leads are properly connected, and the battery is fully charged.

[0034] Current sensor installation: Locate any terminal or connecting wire of the elevator braking resistor, open the opening and closing mechanism of the clip-on current sensor, clamp the wire, ensure that the wire is located in the center of the sensor core, close the opening and closing mechanism and lock it to prevent loosening; there should be no metal obstruction between the sensor and the wire, and the installation position should be far away from strong electromagnetic interference sources such as elevator frequency converters, with a distance of ≥30cm.

[0035] Jumper pressure testing installation: If Wh mode is selected and jumper pressure testing is required, connect the positive and negative terminals of the jumper pressure test probes to the two terminals of the braking resistor respectively. The probes adopt an alligator clip design to ensure reliable clamping. The probe wires are made of high-voltage resistant silicone wire with a withstand voltage rating of ≥1kV and a length of 1.5m for easy installation and wiring. After installation, tidy up the sensor and probe wires to avoid tangling or affecting the operation of other elevator components.

[0036] Power-on check: Restore the elevator's main power supply, start the elevator for trial operation, observe whether the device is powered on normally, whether the current sensor can detect the braking current, and whether the current display is 0 when there is no braking. Check whether the voltage display is normal in the bridging voltage test mode.

[0037] Parameter configuration implementation: Power on: Press the power button to start the device and perform a power-on self-test. The display screen will show information such as sensor detection, storage unit detection, and battery power detection in sequence. After the self-test is passed, the device will enter the main interface and display the "Pending Setup" status.

[0038] Output unit selection: Press the SET button to enter the parameter setting menu, use the up and down buttons to select the “Output Unit” option, press the ACK button to switch to Ah or Wh mode. In this embodiment, Wh mode is selected.

[0039] Statistical time window setting: Select the "Statistical Period" option in the parameter setting menu, press the OK button, and adjust the statistical duration using the up and down selection buttons. In this example, it is set to 7 days. Press the OK button to save.

[0040] Voltage mode selection: Select the "Voltage Mode" option in the parameter setting menu, press the confirmation key, switch to the "Bridge Voltage Measurement" mode, and the display will show "Voltage Measurement Connection in Progress". After confirming that the test probes are connected normally, the voltage value will be displayed as the voltage across the braking resistor. If the connection is abnormal, the message "Voltage Measurement Failure" will be displayed, and the connection needs to be checked again.

[0041] Start metering: After setting the parameters, return to the main interface, press the confirmation button, the device starts metering, records the start time, and the display shows "Running". It updates information such as the running time and the current cumulative energy E in real time.

[0042] Implementation details of braking event recognition and integral calculation Braking event recognition parameter settings: In this embodiment, the current threshold Ith is set to 0.5A, the minimum braking time Tmin is set to 300ms, and the braking end delay time Toff is set to 200ms. The MCU collects the current signal at a low sampling frequency of 1Hz. When the elevator enters the regenerative braking state, the braking current Ib(t) rises rapidly. When Ib(t) ≥ 0.5A and the duration exceeds 300ms, the MCU determines that the braking event has started and immediately switches the sampling frequency to 1kHz. After the braking ends, Ib(t) decreases. When Ib(t) < 0.5A and the duration exceeds 200ms, the braking event is determined to have ended, and the sampling frequency is switched back to 1Hz.

[0043] Integral calculation process: Current sampling: At a sampling frequency of 1kHz, the sampling period Δt = 1ms (0.001 seconds) is used. The MCU reads the current signal collected by ADS1115 through the I2C interface and obtains Ib(t) after filtering. For example, Ib(t) = 10A at a certain sampling point.

[0044] Voltage sampling: Simultaneously read the voltage signal of the bridging voltage measurement module to obtain Ub(t) = 400V.

[0045] Instantaneous power calculation: P(t)=Ub(t)・Ib(t)=400V×10A=4000W (4kW).

[0046] Energy integral: E(Wh)+=P(t)・Δt / 3600=4000W×0.001s / 3600=0.00111Wh, that is, about 0.00111Wh of electrical energy is accumulated every 1ms sampling period, and if the braking is continued for 1 second, the accumulated electrical energy is 4000W×1s / 3600≈1.11Wh.

[0047] Anomaly Handling: If Ib(t) = 60A at a certain sampling point, which exceeds the sensor's 50A range, it is considered abnormal data and discarded. If the Ib(t) fluctuation of 5 consecutive sampling points exceeds ±5A, it is considered spike interference. The moving average algorithm is used to replace the data set to ensure integration accuracy.

[0048] Implementation of statistical time window archiving and historical query: Sealing process: After the device starts metering, the MCU records the running time in real time through the built-in RTC clock. When the running time reaches the preset 7 days, the sealing operation is automatically executed. Data Packaging: Pack the cumulative energy E, start time, end time, statistical duration, voltage mode, average voltage, checksum, and other data for this period into a single data package.

[0049] Storage sealing: Writes the packaged data to a specified storage page in the Flash storage unit, marks it as "sealed", sets it to read-only status, and it cannot be modified.

[0050] The display screen automatically switches to the sealing results interface, showing "Statistics Completed" and continuously displays key information such as cumulative power consumption, start and end time, and statistical duration. After 5 minutes, it switches to the standby interface to reduce power consumption.

[0051] Historical Query: Users press the settings button, enter the menu, select "History", and the display shows a list of all archived records. Users can select a record using the up and down selection buttons and press the confirmation button to view the detailed information of that record. If data needs to be exported, the device is connected to a computer via USB interface. The computer runs dedicated data export software, reads the archived records in Flash via serial communication, and exports them as CSV format files for easy data analysis and reconciliation.

[0052] Low-power operation implementation effect In this embodiment, the low-power strategy of the device is achieved through the switching of the MCU's operating mode and the power control of each module. The specific operating power consumption is as follows: Deep sleep state: The MCU enters STOP2 mode, only the RTC clock runs, and all other modules are powered off. The total power consumption of the device is ≤10μA. This state accounts for about 90% of the time.

[0053] Low-frequency sampling state: The MCU wakes up from deep sleep, starts the current sampling module and RTC clock, and other modules are turned off. The sampling frequency is 1Hz, the single sampling time is ≤1ms, and it immediately returns to deep sleep after sampling is completed. The average power consumption is ≤50μA. This state accounts for about 9.9%.

[0054] High-frequency metering state: During a braking event, the MCU enters RUN mode, all modules operate normally, the sampling frequency is 1kHz, and the total power consumption of the device is ≤50mA. This state accounts for approximately 0.1%.

[0055] Button wake-up / display status: When the user presses a button, the device wakes up and turns on the display backlight, with power consumption ≤60mA. After 5 seconds of inactivity, the backlight turns off and returns to the original state.

[0056] Based on the above power consumption distribution, the 3.7V / 5000mAh battery can support the device to operate continuously for about 30 days, meeting the needs of long-term on-site statistics; if the elevator braking frequency is high, the operating time can reach more than 20 days, fully covering the survey cycle requirements of energy storage and energy-saving renovation projects.

[0057] VI. Verification of Calculation Results To verify the accuracy of the device's calculations, a passenger elevator with a rated load of 1000 kg and a rated speed of 2.0 m / s was selected for testing. Simultaneously, a comparative test was conducted using a DC bus with a standard energy meter installed. The test period was 7 days, and the results are as follows: The device of this invention calculates a cumulative regenerated electrical energy of 852.3 Wh. Cumulative renewable energy calculated by a standard electricity meter: 848.7Wh; The calculation error is approximately 0.42% (852.3-848.7) / 848.7×100%. The error is within ±1%, which meets the accuracy requirements for electricity metering and verifies the accuracy of the device of this invention.

[0058] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A regenerative energy calculation device based on elevator braking resistor circuit current detection, used for elevator regenerative braking energy assessment, characterized in that, include: Clip-on current detection module, used to be clipped onto the elevator braking resistor circuit wire to obtain braking current signal; The metering processing module is used to sample and filter the braking current signal, and identify braking events based on current threshold and duration criteria. The integral calculation module is used to integrate the braking current during the braking event to obtain the cumulative charge Q, and to calculate the instantaneous power by combining the voltage parameters when selecting energy output and to integrate the cumulative electrical energy E. The statistical time window and sealing module is used to accumulate Q or E within a preset statistical time window and seal and store the accumulated amount and corresponding time information at the end of the time window; The device also includes a human-computer interaction and display module for setting and displaying the statistical time window, output unit, and operating status, and for querying archived records; the device further includes a battery-powered and low-power module for supporting long-term portable operation.

2. The regenerative energy calculation device based on elevator braking resistor circuit current detection according to claim 1, characterized in that, The voltage parameter is a preset or user-input fixed voltage Uset, and the instantaneous power is calculated as P(t) = Uset·Ib(t).

3. The regenerative energy calculation device based on elevator braking resistor circuit current detection according to claim 1, characterized in that, It also includes a voltage acquisition module, which is connected across the braking resistor to obtain the braking voltage Ub(t) and performs isolated sampling. The instantaneous power is calculated as P(t) = Ub(t)·Ib(t).

4. The regenerative energy calculation device based on elevator braking resistor circuit current detection according to claim 1, characterized in that, The output unit can be selected between Ah and Wh, and the archived record is saved and displayed according to the selected unit.

5. The regenerative energy calculation device based on elevator braking resistor circuit current detection according to claim 1, characterized in that, The statistical time window is a configurable duration range, preferably 0.5 days to 30 days.

6. The regenerative energy calculation device based on elevator braking resistor circuit current detection according to claim 1, characterized in that, The sealed storage includes at least one of the following: cumulative amount, start and end time or duration of statistical time window, voltage mode information used, and verification information for reconciliation.

7. The regenerative energy calculation device based on elevator braking resistor circuit current detection according to claim 1, characterized in that, The metering processing module only allows the integral calculation module to perform integration during the period when a braking event is detected, and exits the integration state after the braking event ends to reduce erroneous metering.

8. The regenerative energy calculation device based on elevator braking resistor circuit current detection according to claim 1, characterized in that, The low-power module includes at least one of the following: deep sleep and RTC timed wake-up, sampling frequency switching triggered by braking event, and display energy-saving control.

9. A method for calculating the regenerative energy of an elevator using the apparatus according to any one of claims 1-8, characterized in that, include: Sample the braking current and perform conversion; Braking events are identified based on threshold and duration criteria; during the braking event, the current is integrated according to the sampling period to obtain the cumulative charge Q(Ah); when Wh output is selected, the voltage parameters are acquired, the instantaneous power is calculated, and the cumulative energy E(Wh) is obtained by integration; at the end of the preset statistical time window, the cumulative amount and the corresponding time information are sealed and output for display.

10. The measurement method according to claim 9, characterized in that, The sealing step includes writing the data of this statistical time window into non-volatile storage, and setting the data to read-only display after sealing for use in acceptance and reconciliation.

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