A super capacitor safe charging and discharging method and system

Abstract

The application relates to a super capacitor safe charging and discharging method and system, the method comprising a standby process, a calibration process and a charging and discharging management process, wherein the standby process comprises judging whether to start the calibration process according to a set timing condition and judging whether to start the charging and discharging management process according to real-time collected charging and discharging current information; the calibration process comprises calibrating equivalent series resistances of each single body in a super capacitor module and storing a calibration time; and the charging and discharging management process comprises correcting voltages of each single body in the super capacitor module in real time according to the calibrated equivalent series resistances in a charging process, and judging whether to start passive equalization treatment based on the corrected voltages. Compared with the prior art, the application has the advantages of improving safety and reliability and the like.

Description

Technical Field

[0001] This invention relates to the field of supercapacitor charging and discharging safety technology, and in particular to a supercapacitor safe charging and discharging method and system. Background Technology

[0002] Supercapacitors possess higher energy density than traditional capacitors and higher power density than batteries, making them a novel type of power storage device characterized by short charging times and long lifespans. Supercapacitors have two main applications: first, as emergency power supplies for short periods; and second, as peak power sources. In these applications, supercapacitors provide the required peak power to the system independently or, together with batteries, provide a steady-current, low-power supply during continuous operation, and a high-power pulse under peak loads. Supercapacitors reduce the battery's requirement for peak power output from the load. Therefore, the combination of supercapacitors and batteries can provide high power and high energy output, reducing the size of the power source and extending battery life. They are widely used in various scenarios, such as a mobile charging robot based on lithium batteries and supercapacitors, which integrates supercapacitors and lithium batteries for convenient charging of new energy vehicles. Although supercapacitors are safer than lithium batteries, as capacitors, their capacitance is difficult to maintain consistently, leading to voltage imbalances. Overvoltage during charging and improper charging / discharging at high temperatures can result in low charging efficiency, poor output characteristics, and even malfunctions. Therefore, it is necessary to study the safe charging and discharging strategies for supercapacitors. Summary of the Invention

[0003] The purpose of this invention is to overcome the defects of the prior art and provide a safe charging and discharging method and system for supercapacitors that improves safety and reliability.

[0004] The objective of this invention can be achieved through the following technical solutions:

[0005] A safe charging and discharging method for supercapacitors includes a standby process, a calibration process, and a charging and discharging management process, wherein...

[0006] The standby process includes: determining whether to start the calibration process based on the set timing conditions, and determining whether to start the charge and discharge management process based on the real-time collected charge and discharge current information;

[0007] The calibration process includes: calibrating the equivalent series resistance of each individual cell in the supercapacitor module and storing the calibration time;

[0008] The charging and discharging management process includes: during the charging process, the voltage of each cell of the supercapacitor module is corrected according to the calibrated equivalent series resistance, and a decision is made on whether to start passive equalization processing based on the corrected voltage.

[0009] Furthermore, the step of determining whether to start the calibration process based on the set timing conditions specifically involves:

[0010] At set intervals, the current time is obtained and compared with the latest stored calibration time. If the time difference is greater than the set calibration cycle, the calibration process is initiated.

[0011] Furthermore, the calibration of the equivalent series resistance of each individual cell in the supercapacitor module specifically includes:

[0012] Discharge the supercapacitor module until the voltage of a single cell is UoL / 2, where UoL is the capacitor charging cutoff voltage;

[0013] For each individual unit, the following process is performed:

[0014] When charging with constant current Ic for the first time, read the current voltage Ucl, then turn off charging and read the voltage UiL when turning off, and calculate the charging equivalent resistance ESR1=(UoL-UiL) / Ic;

[0015] After a second period of rest, passive equalization is performed on the individual cells. The channel equalization current Ib and the individual cell voltage UbL are read, and the discharge equivalent resistance ESR2 = UbL / Ib – Req is calculated, where Req is the resistance value of the passive equalization resistor.

[0016] The equivalent series resistance rating (ESR) is the average of the charging equivalent resistance (ESR1) and the discharging equivalent resistance (ESR2).

[0017] Furthermore, the calibration process also calibrates the capacity of each individual cell in the supercapacitor module. In the standby process, the capacity value of each individual cell is obtained. If the difference between the highest and lowest individual cell capacity values ​​is greater than a set capacity value, an alarm for excessive capacity difference is sent. The set capacity value is determined based on the calibrated individual cell capacity obtained from the calibration.

[0018] Furthermore, the calibration of the capacity of each individual cell in the supercapacitor module specifically includes:

[0019] Read the voltage value of each unit in the supercapacitor module. If the voltage value of any single unit is greater than the first set voltage, then perform a complete discharge on the supercapacitor module until the voltage values ​​of all units are lower than the second set voltage, and then end the discharge.

[0020] Capacity measurement: The charging mode is set to constant current and constant voltage mode. The supercapacitor module is charged with a fixed current Ic. During the charging process, the charging time required for multiple set charging voltage intervals of each cell is recorded. Multiple capacitance values ​​of each cell are calculated, and the average value of the multiple capacitance values ​​is used as the calibrated cell capacity.

[0021] After the discharge ends, if the voltage values ​​of all cells are lower than the first set voltage within a set duration, the capacity measurement is then performed.

[0022] Furthermore, the step of determining whether to initiate passive equalization processing based on the corrected voltage specifically includes:

[0023] Calculate the voltage difference between the highest and lowest voltage of a single cell after correction. If the voltage difference is greater than a set value, then initiate passive equalization processing for the cell with the highest voltage.

[0024] Furthermore, the charge / discharge management process also includes:

[0025] During charging, if the voltage of any single cell exceeds the overcharge protection voltage, charging will be shut down and a charging protection warning will be issued.

[0026] Furthermore, the charge / discharge management process also includes:

[0027] If the temperature is detected to be higher than the set temperature during charging and discharging, charging and discharging will stop and a high temperature protection warning will be issued.

[0028] Furthermore, in the charging and discharging management process, if no charging or discharging current is detected for a set period of time, the standby process is initiated.

[0029] This invention also provides a supercapacitor safe charging and discharging system, including a charging control switch, a discharging control switch, a voltage measurement module, a charging and discharging current measurement module, a passive equalization module, a storage unit, and a main control MCU. The main control MCU is connected to the charging control switch, the discharging control switch, the voltage measurement module, the charging and discharging current measurement module, the passive equalization module, and the storage unit. The main control MCU performs safe charging and discharging control of the supercapacitor based on the supercapacitor safe charging and discharging method described above.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. This invention first performs data calibration on each individual cell in the supercapacitor module, and then controls safe charging and discharging based on the data calibration results. This method has high reliability, effectively ensures the voltage balance of each cell, and improves charging efficiency and output characteristics.

[0032] 2. This invention can simultaneously calibrate the capacitance and the equivalent series resistance (ESR) of the SDR, achieving capacity balance and further improving the safety of supercapacitor charging and discharging. Attached Figure Description

[0033] Figure 1 This invention relates to the equivalent circuit diagram of a supercapacitor.

[0034] Figure 2 This is a schematic diagram of the ESR calibration of the supercapacitor involved in the present invention;

[0035] Figure 3 This is the equivalent circuit diagram of the supercapacitor passive balancing process involved in this invention;

[0036] Figure 4 This is a flowchart illustrating the charging and discharging process involved in this invention. Detailed Implementation

[0037] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0038] Example 1

[0039] This embodiment provides a safe charging and discharging method for supercapacitors, specifically for mobile charging robots that use a combination of supercapacitors and lithium batteries. The method includes a standby process, a calibration process, and a charging and discharging management process, enabling effective and safe charging and discharging management of the supercapacitor.

[0040] Unlike lithium batteries, supercapacitors often use high currents for rapid charging and discharging. Their equivalent circuit model is attached. Figure 1 As shown, the circuit includes an ideal capacitor C, an equivalent series resistance (ESR), and an equivalent parallel resistance (EPR). In practical applications, supercapacitors often use high currents for charging and discharging, resulting in a significant voltage drop across the ESR. During charging, capacitors with larger ESRs will finish charging before those with smaller ESRs; during discharging, capacitors with larger ESRs will experience a faster voltage drop. The voltage range of a supercapacitor is typically 0V to 2.5V, with a relatively low upper limit for individual cell voltage, making it prone to overcharging, but the discharge voltage can reach 0V. This embodiment designs a safe charging and discharging method for supercapacitors based on the above equivalent circuit model.

[0041] 1. Standby process

[0042] During standby, the system determines whether to start the calibration process based on the set timing conditions, and whether to start the charge / discharge management process based on the real-time collected charge / discharge current information.

[0043] Specifically, the timing condition is set to whether the calibration cycle has been reached. During the standby process, the current time is obtained every set time interval and compared with the latest stored calibration time. If the time difference is greater than the set calibration cycle, the calibration process is initiated. In this embodiment, the set time can be 10 minutes.

[0044] During standby, the current is read at set intervals. When charging / discharging current is detected and remains detected for a sustained period, the charging / discharging management process is initiated. In this embodiment, the set interval is 1 second, and the sustained period is 3 seconds.

[0045] 2. Calibration process

[0046] The calibration process is used to calibrate the equivalent series resistance (ESR0-ESRn) of each cell in the supercapacitor module and stores the calibration time. In a preferred embodiment, the calibration process also calibrates the capacitance of each cell in the supercapacitor module. During standby, the capacitance value of each cell is acquired. If the difference between the highest and lowest capacitance values ​​of a cell is greater than a set capacitance value, an alarm indicating excessive capacitance difference is sent. The set capacitance value is determined based on the calibrated cell capacitance obtained during calibration; specifically, the set capacitance value can be 15% of the calibrated cell capacitance. The capacitance values ​​C0-Cn, equivalent series resistances (ESR0-ESRn), and calibration time of each cell obtained during each calibration are stored to facilitate determination of the calibration cycle during standby.

[0047] In this embodiment, as Figure 2 As shown, the calibration of the capacity of each individual cell in the supercapacitor module specifically includes:

[0048] Read the voltage value of each unit in the supercapacitor module. If the voltage value of any single cell is greater than the first set voltage, such as 10mV, then perform a complete discharge on the supercapacitor module until the voltage value of all cells is lower than the second set voltage, such as 5mV. Then the discharge ends. If the voltage value of all cells is lower than the first set voltage within the set time period, then it is considered that all single cell capacitors have been deeply discharged. Then the capacity measurement is started. The set time period can be 3 minutes.

[0049] Capacity Measurement: The charging mode is set to constant current and constant voltage mode. The supercapacitor module is charged with a fixed current Ic. During the charging process, the charging time required for multiple set charging voltage intervals of each cell is recorded. Multiple capacitance values ​​of each cell are calculated, and the average value of multiple capacitance values ​​is used as the calibrated cell capacity.

[0050] In the above capacity calibration, the capacitor charging cutoff voltage is set as UoL, and the capacitance value is calculated using formula ① C=I(Δt / Δv). Since the capacitance SOC and voltage have a linear relationship, starting from 0V, the time points t1~t6 corresponding to the increase to Δv are recorded according to Δv=UoL-0V / 6. Then, the six sets of capacitance values ​​for each individual capacitor are calculated using formula ①, and the average value is taken to obtain the calibrated C0~Cn.

[0051] In a preferred embodiment, when measuring the capacitance, if the voltage value of a certain capacitor reaches UoL, but the entire group does not reach UoL, then passive balancing is activated for the capacitors that have reached UoL.

[0052] After the capacity measurement is completed, the equivalent series resistance (ESR) can be calibrated. The calibration of the ESR of each individual cell in the supercapacitor module specifically includes:

[0053] The supercapacitor module is discharged until the voltage of a single cell reaches UoL / 2, where UoL is the capacitor charging cutoff voltage. Then, the ESR calibration process is repeated for all cells. The process is as follows: First, charging is performed with a constant current Ic for a period of time, e.g., 30 seconds. The current voltage Ucl is read. Then, charging is stopped, and immediately after stopping, the voltage UiL is read. Considering that the capacitor voltage cannot change abruptly, the voltage drop after the charging current disappears is the voltage drop across the ESR resistor. The equivalent charging resistance ESR1 is calculated as (UoL - UiL) / Ic. A second rest period, e.g., 60 seconds, is performed on the currently calibrated capacitor cell for passive equalization. The channel equalization current Ib and the cell voltage UbL are read. The equivalent circuit with the passive equalization resistor is shown below. Figure 3 As shown, the discharge equivalent resistance ESR2 = UbL / Ib – Req is calculated, where Req is the passive equalization resistor value; the equivalent series resistance rating ESR is the average value of the charging equivalent resistance ESR1 and the discharging equivalent resistance ESR2.

[0054] 3. Charging and discharging management process

[0055] During charging, the voltage of each cell in the supercapacitor module, which is acquired in real time, is corrected based on the calibrated equivalent series resistance. The system then determines whether to initiate passive equalization processing based on the corrected voltage. Specifically, the voltage difference between the highest and lowest voltage of a cell after correction is calculated. If the voltage difference exceeds a set value, passive equalization processing is initiated for the cell with the highest voltage.

[0056] In a preferred embodiment, the charge and discharge management process further includes: during the charging process, if the voltage of any single cell exceeds the overcharge protection voltage, charging is shut down and a charging protection warning is issued.

[0057] In a preferred embodiment, the charging and discharging management process further includes: during the charging and discharging process, if the temperature is detected to be higher than the set temperature, such as 80°C, the charging and discharging is stopped and a high temperature protection warning is issued.

[0058] In the charging and discharging management process, if no charging or discharging current is detected for a set period of time, such as 5 minutes without detecting charging or discharging current, the standby process is initiated.

[0059] The above methods can achieve charging protection and capacity balancing during charging, thereby enabling effective and safe charging and discharging management of supercapacitors.

[0060] Example 2

[0061] This embodiment provides a safe charging and discharging system for supercapacitors, including a charging control switch, a discharging control switch, a voltage measurement module, a charging and discharging current measurement module, a passive balancing module, a storage unit, and a main control MCU. The main control MCU is connected to the charging control switch, the discharging control switch, the voltage measurement module, the charging and discharging current measurement module, the passive balancing module, and the storage unit. (Reference) Figure 4 As shown, the system achieves safe charging and discharging control of the supercapacitor through the following steps:

[0062] Step S1: After the system is powered on, read the current system time, and the most recently calibrated capacity values ​​C0 to Cn, equivalent series resistances ESR0 to ESRn, and stored calibration time of each cell in the storage unit. If there is no stored value or the difference between the current time and the calibration time exceeds the specified calibration period, proceed to step S2; otherwise, proceed to step S3.

[0063] Step S2: Calibrate the supercapacitor capacitance and the equivalent resistance (ESR) in the equivalent circuit model. Read the capacitor voltage values. If the voltage of any single cell is greater than 10mV, first perform a complete discharge of the capacitor. If the discharge switch is turned on and a load current is detected, then perform rapid discharge through the load. Otherwise, turn on the passive equalization switch and discharge through the passive equalization module until all single cell voltages are detected to be below 5mV. If, after turning off the discharge switch, all single cell voltages remain below 10mV after 3 minutes of rest, then all single cell capacitors are considered to have completed deep discharge, and capacitance measurement will then begin. The capacitor charging cutoff voltage is set as UoL. Using formula ① C=I(Δt / Δv), the charging mode is set to constant current and constant voltage mode. The capacitor bank is charged with a fixed current Ic. During the charging process, the main control unit quickly reads the voltage values ​​of all individual cells. Since the capacitor SOC and voltage have a linear relationship, according to Δv=UoL-0V / 6, starting from 0V, the time points t1~t6 corresponding to the increase to Δv are recorded. Then, the six sets of capacitance values ​​of each individual capacitor are calculated by formula ①, and the average value is taken to obtain the calibrated C0~Cn.

[0064] When measuring capacitance, if the voltage of a certain capacitor reaches UoL, but the entire group does not reach UoL, then passive equalization is activated for the capacitors that have reached UoL.

[0065] After the capacitance measurement is completed, the entire capacitor bank is discharged until the voltage of a certain capacitor is UoL / 2. Then, the ESR test procedure is performed on all individual cells in cycles. The procedure is as follows: First, charge with a constant current Ic for 30 seconds, read the current voltage Ucl, then stop charging, and immediately read the voltage UiL after stopping. Considering that the capacitor voltage cannot change abruptly, the voltage drop after the charging current disappears is the voltage drop across the ESR resistor, thus obtaining ESR(charging) = (UoL - UiL) / Ic; then let it rest for 60 seconds, then turn on the passive equalization of the current test capacitor. Immediately after turning it on, read the channel equalization current Ib and the individual capacitor voltage UbL, thus obtaining Ib(ESR + Req) = UbL, and ESR(discharging) = UbL / ib – Req, where Req is the resistance value of the passive equalization resistor. Finally, the ESR value is taken as the average of the charging and discharging values.

[0066] After the volume measurement and ESR measurement are completed, proceed to step S3.

[0067] S3: Standby Procedure. The current time is read every 10 minutes and compared with the most recently stored calibration time in the storage unit. If the time difference is greater than the set calibration period, proceed to step S2. If not, the measured capacitance values ​​of each cell are checked. If the difference between the highest and lowest capacitance values ​​is 15% or more of the standard capacity, a capacity difference alarm is sent.

[0068] Read the current every 1 second. If the charging and discharging current is detected for 3 consecutive seconds, then proceed to step S4.

[0069] S4: Charge / Discharge Control Process. During charging, the supercapacitor voltage is corrected based on the ESR calibrated in step S2, and the calibrated voltage is used as the standard for initiating passive equalization. The difference between the highest and lowest voltages after calibration is taken. If the voltage difference is greater than the set value, the passive equalization unit of the highest voltage cell is activated. If it exceeds the overcharge protection voltage, charging is stopped and a charging protection warning is issued.

[0070] If no charging or discharging current is detected for 5 minutes, proceed to stage S3.

[0071] In a preferred embodiment, the system further includes a temperature measurement module. If the temperature is detected to be greater than 80°C during the charging and discharging process, the charging and discharging process is stopped and a high-temperature protection warning is issued.

[0072] The preferred embodiments of the present invention have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of the present invention without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of the present invention through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A safe charging and discharging method for a supercapacitor, characterized in that, This includes standby procedures, calibration procedures, and charge / discharge management procedures, among which... The standby process includes: determining whether to start the calibration process based on the set timing conditions, and determining whether to start the charge and discharge management process based on the real-time collected charge and discharge current information; The calibration process includes: calibrating the equivalent series resistance of each individual cell in the supercapacitor module and storing the calibration time; The charging and discharging management process includes: during the charging process, the voltage of each cell of the supercapacitor module is corrected according to the calibrated equivalent series resistance, and the passive equalization process is determined based on the corrected voltage. The calibration of the equivalent series resistance of each individual cell in the supercapacitor module specifically includes: Discharge the supercapacitor module until the voltage of a single cell is UoL / 2, where UoL is the capacitor charging cutoff voltage; For each individual unit, the following process is performed: When charging with constant current Ic for the first time, read the current voltage Ucl, then turn off charging and read the voltage UiL when turning off, and calculate the charging equivalent resistance ESR1 = (UoL-UiL) / Ic; After a second period of rest, passive equalization is performed on the individual cells. The channel equalization current Ib and the individual cell voltage UbL are read, and the discharge equivalent resistance ESR2 = UbL / Ib - Req is calculated, where Req is the resistance value of the passive equalization resistor. The equivalent series resistance rating (ESR) is the average of the charging equivalent resistance (ESR1) and the discharging equivalent resistance (ESR2). The calibration process also calibrates the capacity of each cell in the supercapacitor module. In the standby process, the capacity value of each cell is obtained. If the difference between the highest and lowest cell capacity values ​​is greater than a set value, an alarm for excessive capacity difference is sent. The set value is determined based on the calibrated cell capacity obtained from the calibration. The calibration of the capacity of each individual cell in the supercapacitor module specifically includes: Read the voltage value of each cell in the supercapacitor module. If the voltage value of any cell is greater than the first set voltage, then perform a complete discharge of the supercapacitor module until the voltage values ​​of all cells are lower than the second set voltage, and then end the discharge. Capacity measurement: The charging mode is set to constant current and constant voltage mode. The supercapacitor module is charged with a fixed current Ic. During the charging process, the charging time required for multiple set charging voltage intervals of each cell is recorded. Multiple capacitance values ​​of each cell are calculated, and the average value of the multiple capacitance values ​​is used as the calibrated cell capacity. After the discharge ends, if the voltage values ​​of all cells are lower than the first set voltage within a set duration, the capacity measurement is then performed.

2. The safe charging and discharging method for a supercapacitor according to claim 1, characterized in that, The specific steps for determining whether to start the calibration process based on the set timing conditions are as follows: At set intervals, the current time is obtained and compared with the latest stored calibration time. If the time difference is greater than the set calibration cycle, the calibration process is initiated.

3. The safe charging and discharging method for a supercapacitor according to claim 1, characterized in that, The specific steps for determining whether to initiate passive equalization processing based on the corrected voltage include: Calculate the voltage difference between the highest and lowest voltage of a single cell after correction. If the voltage difference is greater than a set value, then initiate passive equalization processing for the cell with the highest voltage.

4. The safe charging and discharging method for a supercapacitor according to claim 1, characterized in that, The charge / discharge management process also includes: During charging, if the voltage of any single cell exceeds the overcharge protection voltage, charging will be shut down and a charging protection warning will be issued.

5. The safe charging and discharging method for a supercapacitor according to claim 1, characterized in that, The charge / discharge management process also includes: If the temperature is detected to be higher than the set temperature during charging and discharging, charging and discharging will stop and a high temperature protection warning will be issued.

6. The safe charging and discharging method for a supercapacitor according to claim 1, characterized in that, In the charging and discharging management process, if no charging or discharging current is detected for a set period of time, the standby process is initiated.

7. A safe charging and discharging system for a supercapacitor, characterized in that, It includes a charging control switch, a discharging control switch, a voltage measurement module, a charging / discharging current measurement module, a passive balancing module, a storage unit, and a main control MCU. The main control MCU is connected to the charging control switch, the discharging control switch, the voltage measurement module, the charging / discharging current measurement module, the passive balancing module, and the storage unit. The main control MCU performs safe charging and discharging control of the supercapacitor based on the supercapacitor safe charging and discharging method as described in any one of claims 1-6.

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