Super capacitor energy storage unit management system

Abstract

The invention provides a super-capacitor energy storage unit management system, which is characterized in that a plurality of super-capacitor monomers are connected in parallel to form a super-capacitor module, a plurality of super-capacitor modules are connected in series to form an energy storage unit, and each super-capacitor module is controlled by a switch control unit to perform charge-discharge circulation and standing self-recovery in turn. A balance management system (BMS) maintains voltage balance when the capacitance variable quantity of the super-capacitor is different, a voltage balance unit between modules eliminates voltage imbalance between series super-capacitor modules, and a communication unit can transmit state information such as system voltage, the capacitance of the super-capacitor, internal resistance and the like and control information such as cycle index, cut-off voltage and the like. Man-machine interaction is carried out through a computer, the capacity and internal resistance monitoring unit is combined with the alarm unit to give an alarm after abnormity is monitored, the service life of the super-capacitor is effectively prolonged, the use efficiency of the super-capacitor is improved, the safety of the energy storage unit is guaranteed, the temperature and current variable control unit is additionally arranged, and the safety of the energy storage unit is improved. And the service life of the super capacitor is further prolonged.

Description

Technical Field

[0001] The present invention relates to the field of power electronics technology, and in particular to a supercapacitor energy storage unit management system. Background Art

[0002] Supercapacitor is a new type of energy storage element between traditional capacitors and chemical batteries. Compared with conventional energy storage devices, it has the advantages of high charging and discharging efficiency and high energy density. The working environment of supercapacitors is usually harsh, so the actual service life is generally lower than expected, and supercapacitors decay with each use. The increase in the number of cycles is often accompanied by performance degradation and increased aging, which is specifically manifested in performance parameters as an increase in internal resistance and a decrease in capacitance. Moreover, the rated voltage of a single supercapacitor is low, and it is generally necessary to use supercapacitor modules in series and parallel. At the same time, due to differences in production processes, the capacity of supercapacitors cannot be completely consistent, so the resulting voltage imbalance problem will also seriously affect the service life of the capacitor.

[0003] There are two mainstream solutions to the problem of supercapacitor service life: one is to improve the working environment. Existing studies have shown that the life of supercapacitors is greatly affected by temperature, voltage, and current. The service life can be effectively extended by adjusting system temperature, cut-off voltage, charge and discharge current and other parameters; the second is to add compensating supercapacitors and voltage balancing systems, and achieve voltage equalization control through a balanced management system (Balanced Management System, referred to as BMS). After monitoring the abnormal capacitance and internal resistance of the supercapacitor, the compensating capacitor is put into use to maintain the normal operation of the system. This method will also lead to a reduction in the utilization rate of the capacitor.

[0004] None of the above solutions take into account the self-recovery effect of the supercapacitor and cannot solve the problem of capacitance drop under high-frequency charge and discharge cycles during use of the supercapacitor. Summary of the invention

[0005] The present invention provides a supercapacitor energy storage unit management system, which combines traditional solutions and takes into account the self-recovery effect of supercapacitors, organizes supercapacitors into supercapacitor modules, and controls the connection and disconnection of each module so that each supercapacitor module switches between the two states of charge and discharge cycle and static self-recovery, thereby effectively increasing the service life and use efficiency of the supercapacitor.

[0006] The technical solution to achieve the purpose of the present invention is: a supercapacitor energy storage unit management system, including a supercapacitor energy storage unit, a switch control unit, a voltage regulation unit, a capacity and internal resistance monitoring unit, an alarm unit, a communication unit, an inter-module voltage balancing unit and a computer;

[0007] The supercapacitor energy storage unit includes a plurality of supercapacitor modules, each of which is connected in series in sequence, each of which includes a plurality of supercapacitors, each of which is connected to a BMS system, and both ends of each supercapacitor are connected in parallel, one end of each supercapacitor connected to the positive electrode is the supercapacitor module input end, and one end of each supercapacitor connected to the negative electrode is the supercapacitor module output end, the front supercapacitor module input end is connected to the DC bus through a bidirectional DC / DC converter, each supercapacitor module output end is connected to the first module switch input end, each supercapacitor module input end is connected to the second module switch input end, and the second module switch output end is connected to the first module switch output end;

[0008] The switch control unit is used to control the branch switch, the first module switch and the second module switch so that the supercapacitor branches of each supercapacitor module perform charge-discharge cycles and self-recovery in turn;

[0009] The voltage regulating unit is used to adjust the cut-off voltage of each supercapacitor charge and discharge cycle. Different voltage conditions can change the self-recovery effect of the supercapacitor. By reasonably setting the cut-off voltage, the service life of the system can be extended.

[0010] The capacity and internal resistance monitoring unit is used to monitor the capacity and internal resistance of each supercapacitor module and a single supercapacitor, and terminate the charge and discharge cycle when the capacity is too low or the internal resistance is too high;

[0011] The alarm unit is used to send out an alarm when a system abnormality is detected;

[0012] The communication unit is used to collect and transmit system status information and control instructions in real time;

[0013] The inter-module voltage balancing unit is used to eliminate voltage imbalance between series-connected supercapacitor modules;

[0014] The computer is used for human-computer interaction with each unit of the system;

[0015] Optionally, the system also includes a charge and discharge current control unit and a temperature acquisition unit

[0016] The charge and discharge current control unit is used to adjust the charge and discharge rate of each supercapacitor module during the cycle, and reasonably set the rate according to the cycle time and load requirements to extend the service life of the system;

[0017] The temperature acquisition unit is used to monitor the temperature of each module of the system in real time, and to issue an alarm through the alarm unit when the temperature exceeds or falls below a set threshold.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] Compared with the traditional solution, the self-recovery effect of the supercapacitor is taken into consideration, and multiple supercapacitor monomers are connected in parallel to form a supercapacitor module. Multiple supercapacitor modules are connected in series to form an energy storage unit. The switch control unit controls each supercapacitor module to perform charge and discharge cycles and static self-recovery in turn. The BMS system can maintain voltage balance when the supercapacitor capacitance changes differently. The inter-module voltage balancing unit can eliminate the voltage imbalance between the series supercapacitor modules. The communication unit can transmit system voltage, supercapacitor capacitance, internal resistance and other status information and control information such as the number of cycles and cut-off voltage. Human-computer interaction is performed through a computer. The capacity and internal resistance monitoring unit combined with the alarm unit can issue an alarm after detecting an abnormality, so that the operator can take corresponding measures in time. The above settings effectively extend the service life of the supercapacitor and improve its utilization efficiency, and also ensure the safety of the energy storage unit. The temperature and current variable control unit are added to further extend the service life of the supercapacitor. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0021] Figure 1 This is a diagram of supercapacitor capacity attenuation and self-recovery effect under 2.8V conditions;

[0022] Figure 2 This is a diagram showing the increase in internal resistance and self-recovery effect of supercapacitors at 2.8V;

[0023] Figure 3 This is a diagram of supercapacitor capacity attenuation and self-recovery effect under 2.4V conditions;

[0024] Figure 4 This is a diagram showing the increase in internal resistance and self-recovery effect of supercapacitors under 2.4V conditions;

[0025] Figure 5 A schematic diagram of the architecture of a supercapacitor energy storage unit management system provided in an embodiment of the present disclosure;

[0026] Figure 6 This is the operation flow chart of the supercapacitor energy storage unit management system. DETAILED DESCRIPTION

[0027] Embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although certain embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as being limited to the embodiments described herein, which are instead provided for a more thorough and complete understanding of the present invention. It should be understood that the drawings and embodiments of the present invention are only for exemplary purposes and are not intended to limit the scope of protection of the present invention.

[0028] The technical solution of the present invention is described in detail with specific embodiments below. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0029] The self-healing effect of supercapacitors can be verified by the following experiments:

[0030] The cutoff voltages of the two supercapacitors were set to 2.8V and 2.4V respectively, and the supercapacitors were subjected to 150,000 charge and discharge cycles, with a short rest period every 50,000 times, the first rest period being 1 day and the second being 8 days.

[0031] like Figure 1 and Figure 2 As shown in the figure, under 2.8V conditions, the capacity decay of the two supercapacitors in the first 50,000 charge and discharge cycles was 22.76% and 21.38%, respectively, and the internal resistance increased by 75.18% and 78.81%, respectively. The capacitance decay of the second 50,000 charge and discharge cycles was 22.66% and 15.43%, respectively, and the internal resistance increased by 58.16% and 51.66%, respectively. The capacitance decay of the third 50,000 charge and discharge cycles was 17.95% and 17.76%, respectively, and the internal resistance increased by 72.34% and 78.15%, respectively. When the standing time was 1 day, the capacity could be restored by 16.47% and 13.99%, respectively, and the internal resistance decreased by 51.77% and 50.33%, respectively. When the standing time was 8 days, the capacity could be restored by 17.83% and 17.56%, respectively, and the internal resistance decreased by 78.72% and 73.51%, respectively.

[0032] like Figure 3 and Figure 4As shown in the figure, under 2.4V conditions, the capacity decay of the three supercapacitors in the first 50,000 charge and discharge cycles was 10.00%, 11.38%, and 11.70%, respectively, and the internal resistance increased by 11.70%, 25.17%, and 23.81%, respectively. The capacity decay of the second 50,000 charge and discharge cycles was 8.30%, 7.67%, and 7.83%, respectively, and the capacitance increased by 30.99%, 24.49%, and 42.86%, respectively. The capacity decay of the third 50,000 charge and discharge cycles was 8.25%, 9.10%, and 8.63%, respectively, and the internal resistance increased by 29.82%, 44.22%, and 36.05%, respectively. When the standing time is 1 day, the capacity can be recovered by 7.5%, 6.55% and 6.84% respectively, and the internal resistance can be reduced by 23.98%, 38.78% and 38.78% respectively. When the standing time is 8 days, the capacity can be recovered by 8.57%, 8.74% and 7.41% respectively, and the internal resistance can be reduced by 37.43%, 27.90 and 45.58% respectively.

[0033] Experimental data show that if the supercapacitor is left idle for a period of time after a certain number of cycles, its capacitance and internal resistance will be restored to a certain extent. This effect can be used to optimize the system design and combined with existing methods to further extend the service life of the supercapacitor and improve the utilization rate of the supercapacitor.

[0034] Figure 5 A supercapacitor energy storage unit management system provided in an embodiment of the present disclosure includes a supercapacitor energy storage unit, a switch control unit, a voltage regulating unit, a capacity and internal resistance monitoring unit, an alarm unit, a communication unit, an inter-module voltage balancing unit and a computer;

[0035] The supercapacitor energy storage unit includes n supercapacitor modules, each of which is connected in series in sequence, each of which includes multiple supercapacitors, each of which is connected to the BMS system, and both ends of each supercapacitor are connected in parallel. The end connected to the positive electrode of each supercapacitor is the input end of the supercapacitor module, and the end connected to the negative electrode of each supercapacitor is the output end of the supercapacitor module. The frontmost supercapacitor module input end is connected to the DC bus through a bidirectional DC / DC converter, and each supercapacitor module output end is connected to the first module switch input end, each supercapacitor module input end is connected to the second module switch input end, and the second module switch output end is connected to the first module switch output end;

[0036] A switch control unit, used to control the branch switch, the first module switch and the second module switch, so that the supercapacitor branches of each supercapacitor module perform charge-discharge cycles and self-recovery in turn;

[0037] The voltage regulating unit is used to adjust the cut-off voltage of each supercapacitor charge and discharge cycle. Different voltage conditions can change the self-recovery effect of the supercapacitor. By reasonably setting the cut-off voltage, the service life of the system can be extended.

[0038] The capacity and internal resistance monitoring unit is used to monitor the capacity and internal resistance of each supercapacitor module and a single supercapacitor. When the capacity is too low or the internal resistance is too high, the charge and discharge cycle is terminated.

[0039] An alarm unit is used to issue an alarm when a system abnormality is detected;

[0040] Communication unit, used for real-time collection and transmission of system status information and control instructions;

[0041] Inter-module voltage balancing unit, used to eliminate voltage imbalance between series-connected supercapacitor modules;

[0042] Computer, used for human-computer interaction with each unit of the system;

[0043] The charge and discharge current control unit is used to adjust the charge and discharge rate of each supercapacitor module cycle, and reasonably set the rate according to the cycle time and load requirements to extend the service life of the system;

[0044] The temperature collection unit is used to monitor the temperature of each module in the system in real time, and issue an alarm through the alarm unit when the temperature exceeds or falls below the set threshold.

[0045] The operation process of this system is as follows:

[0046] like Figure 6 As shown, before the system runs normally, the system first executes the initialization program, and then sets the number of cycles and cut-off voltage before self-recovery of each module. After completion, the communication unit sends a command to the switch control unit, and the system starts running. Starting from supercapacitor module #1, the first module switch S of supercapacitor module #1 11 The second module switch S 12 The first module switches S of the remaining supercapacitor modules are turned off. k1 Disconnect, the second module switch S k2 On (k = 2, 3, ..., n), that is, switch S 11 , S 12 The controlled supercapacitor module #1 enters the self-recovery state, and the other supercapacitor modules perform charge and discharge cycles. After the set number of cycles is met, the switch S 11 Turn off, switch S 12 The supercapacitor module 1# ends self-recovery and starts the charge and discharge cycle. At the same time, the switch S 21 On, switch S 22Shut down, supercapacitor module 2# ends the charge and discharge cycle and performs self-recovery. After that, each module switches state in turn after meeting the number of charge and discharge cycles. After supercapacitor module #n completes self-recovery, it returns to supercapacitor module 1# to restart the alternating self-recovery and charge and discharge cycle of each module. While the system is running, the operator can perform human-computer interaction through a computer combined with a communication unit connected to each unit of the system. The communication unit can collect system status information in real time and transmit computer instructions to timely regulate the system. Considering the difference in the initial capacitance and capacitance change of each supercapacitor, the voltage balancing control of the supercapacitor is performed through the BMS system. The capacitance attenuation degree of each supercapacitor module is usually different. In addition, the difference in production process makes it difficult to unify the initial capacitance of the supercapacitor. The negative impact of voltage imbalance is eliminated through the voltage balancing unit between modules. At the same time, the capacity and internal resistance monitoring unit monitors the capacity and internal resistance of each supercapacitor module and a single supercapacitor. When the capacity is too low or the internal resistance is too high, the charge and discharge cycle is terminated and an alarm is issued through the alarm unit.

[0047] In addition, a charging and discharging current control unit and a temperature collection unit are added to increase the control variables, further effectively extending the service life and efficiency of the supercapacitor.

Claims

1. A supercapacitor energy storage unit management system, characterized in that: It includes a supercapacitor energy storage unit, a switch control unit, a voltage regulation unit, a capacity and internal resistance monitoring unit, an alarm unit, a communication unit, an inter-module voltage balancing unit and a computer; The supercapacitor energy storage unit includes a plurality of supercapacitor modules, each of which is connected in series in sequence, each of which includes a plurality of supercapacitors, each of which is connected to a BMS system, and both ends of each supercapacitor are connected in parallel, one end of each supercapacitor connected to the positive electrode is the supercapacitor module input end, and one end of each supercapacitor connected to the negative electrode is the supercapacitor module output end, the front supercapacitor module input end is connected to the DC bus through a bidirectional DC / DC converter, each supercapacitor module output end is connected to the first module switch input end, each supercapacitor module input end is connected to the second module switch input end, and the second module switch output end is connected to the first module switch output end; The switch control unit is used to control the first module switch and the second module switch so that the supercapacitor branches of each supercapacitor module perform charge-discharge cycles and self-recovery in turn; The voltage regulating unit is used to adjust the cut-off voltage of each supercapacitor charge and discharge cycle. Different voltage conditions can change the self-recovery effect of the supercapacitor. The cut-off voltage can be reasonably set to extend the service life of the system. The capacity and internal resistance monitoring unit is used to monitor the capacity and internal resistance of each supercapacitor module and a single supercapacitor, and terminate the charge and discharge cycle when the capacity is too low or the internal resistance is too high; The alarm unit is used to send out an alarm when a system abnormality is detected; The communication unit is used to collect and transmit system status information and control instructions in real time; The inter-module voltage balancing unit is used to eliminate voltage imbalance between series-connected supercapacitor modules; The computer is used for human-computer interaction with each unit of the system.

2. The supercapacitor energy storage unit management system according to claim 1, characterized in that: It also includes a charge and discharge current control unit and a temperature acquisition unit The charge and discharge current control unit is used to adjust the charge and discharge rate of each supercapacitor module during the cycle, and reasonably set the rate according to the cycle time and load requirements to extend the service life of the system; The temperature acquisition unit is used to monitor the temperature of each module of the system in real time, and to issue an alarm through the alarm unit when the temperature exceeds or falls below a set threshold.

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