Discharging apparatus, charging and discharging system, and operating method therefor

Abstract

A discharging apparatus, a charging and discharging system, and an operating method therefor. The discharging apparatus comprises an energy storage element and a load unit. The energy storage element is charged at a constant current and, when the voltage of the energy storage element reaches a reference voltage, the load unit is enabled, so that the energy storage element is discharged at a constant voltage to a fixed voltage.

Description

Discharge device, charge and discharge system having the same and method of operating the same TECHNICAL FIELD

[0001] The present invention relates to a discharge device, a charge and discharge system having the same and a method of operating the same, and more particularly to a discharge device charging at a constant current and discharging at a constant voltage, a charge and discharge system having the same and a method of operating the same. BACKGROUND

[0002] There are many applications of batteries that require accurate control of the target voltage of the battery and reduction of the voltage difference between individuals.

[0003] Referring to FIG. 1, the current method is to individually charge using a separate charger using a constant current (CC) and constant voltage (CV) method without any series or parallel connection. However, when the charging is completed, the voltage of the battery usually drops due to phenomena such as the dissipation of surface charge of the battery electrode, the rebalancing of lithium ion concentration inside the battery, or self-discharge, as illustrated after time t3' in FIG. 1.

[0004] However, the CC charging and CV charging method has the following disadvantages: 1. It cannot be used for series charging, as the battery has individual differences, so CV charging cannot be performed when connected in series, resulting in the inability to improve productivity through series connection. 2. The CV charging process is time-consuming, as it needs to be charged to a small current cutoff to reduce the above-mentioned voltage drop phenomenon and stabilize the battery voltage, thus significantly affecting the production line productivity.

[0005] Therefore, how to design a discharge device, a charge and discharge system having the same and a method of operating the same to solve the problems and technical bottlenecks existing in the prior art is an important subject of research for the present inventors.

[0006] SUMMARY

[0007] An object of the present invention is to provide a discharge device including an energy storage element and a load unit. The energy storage element is charged at a constant current, and when the voltage of the energy storage element reaches a reference voltage, the load unit is enabled to discharge the energy storage element at a constant voltage to a fixed voltage.

[0008] In one embodiment, the discharging device further comprises a switch, a controller, and an isolated communication element. The switch is connected in series with the energy storage element to form a first series branch, and the load unit is connected in parallel with the first series branch or the energy storage element. The controller is coupled to the switch. The isolated communication element is connected to the controller and receives an external control signal. The controller controls the switch to be turned on according to the external control signal, so that the energy storage element is charged at a constant current.

[0009] In one embodiment, the energy storage element is charged by a power supply.

[0010] In one embodiment, after the energy storage element is charged at a constant current for a period of time, the load unit is enabled when the voltage of the energy storage element reaches a reference voltage corresponding to the discharging device, so that the energy storage element is charged at a constant voltage to a fixed voltage or discharged at a constant voltage to a fixed voltage.

[0011] In one embodiment, when the voltage of the energy storage element reaches the reference voltage, the load unit is enabled, so that the energy storage element is discharged at a constant current to replace the constant voltage discharge to a fixed voltage.

[0012] In one embodiment, the controller generates a first control signal to control the switch.

[0013] In one embodiment, the discharging device further comprises a connector. The connector connects the power supply and the energy storage element.

[0014] In one embodiment, during the constant current charging process, the voltage of the energy storage element is less than the full charge voltage of the energy storage element.

[0015] In one embodiment, the load unit comprises a switching element, a resistive element, and a feedback control unit. The resistive element is connected in series with the switching element. The feedback control unit is connected to the switching element and generates a load control signal to control the switching element.

[0016] In one embodiment, the feedback control unit receives the voltage of the energy storage element and a reference voltage, and compares the voltage with the reference voltage. The load control signal controls the impedance of the switching element, so that the voltage of the energy storage element is maintained at a constant value.

[0017] In one embodiment, the discharging device further comprises a bypass switch. The bypass switch is connected in parallel with the first series branch. When the bypass switch is turned on and the switch is turned off, the charging operation of the energy storage element is bypassed.

[0018] In one embodiment, the controller generates a second control signal to control the bypass switch.

[0019] Thus, the discharging device has the following features and advantages: 1. Precise battery output voltage can be achieved by constant current charging and constant voltage discharging provided by the load unit; 2. The time of overall constant current charging and constant voltage discharging is significantly shortened, and a large amount of charging time can be saved; 3. The energy storage elements are controlled to have the same or similar remaining capacity (e.g. less than 0.5% difference) before subsequent charging and discharging control, so that energy saving effect can be achieved; 4. A large number of batteries can achieve higher output voltage concentration (i.e. reduce the voltage difference between the batteries) after charging and discharging operation by the present application, so that the time required for charging the batteries to a certain target voltage can be shortened.

[0020] Another object of the present application is to provide a charging and discharging system including a plurality of discharging devices and a plurality of energy storage elements connected in series. Each discharging device is used to discharge each energy storage element. Each discharging device includes a switch, a load unit, a controller, and an isolated communication element. The switch is connected in series with the energy storage element to form a first series branch. The load unit is connected in parallel with the first series branch or the energy storage element. The controller is coupled to the switch. The isolated communication element is connected to the controller and receives an external control signal. Each controller controls the switch to be turned on according to the external control signal, so that the energy storage element is charged with a constant current, and when the voltage of the energy storage element reaches a reference voltage, the load unit is enabled to discharge the energy storage element at a constant voltage to a fixed voltage.

[0021] In an embodiment, the energy storage elements are charged by a power supply.

[0022] In an embodiment, after each energy storage element is charged with a constant current for a period of time, when the voltage of each energy storage element reaches a reference voltage corresponding to the discharging device, the load unit is enabled to charge or discharge each energy storage element at a constant voltage to a fixed voltage.

[0023] In an embodiment, when the voltage of each energy storage element reaches the reference voltage, the load unit is enabled to discharge each energy storage element at a constant current instead of at a constant voltage to a fixed voltage.

[0024] In an embodiment, each discharging device further includes two connectors. One of the connectors is connected to the power supply and the energy storage element, and the other connector is connected to another discharging device.

[0025] In an embodiment, during the constant current charging process, the voltage of the energy storage element is less than the full charge voltage of the energy storage element.

[0026] In an embodiment, each load unit includes a switching element, a resistive element, and a feedback control unit. The resistive element is connected in series with the switching element. The feedback control unit is connected to the switching element and generates a load control signal to control the switching element.

[0027] In one embodiment, the feedback control unit receives a voltage of the energy storage element and a reference voltage, and compares the voltage with the reference voltage. The load control signal controls the impedance of the switching element, so that the voltage of each energy storage element is maintained at a constant value.

[0028] In one embodiment, each discharging device further comprises a bypass switch. The bypass switch is connected in parallel with the first series branch. When the bypass switch is turned on and the switch is turned off, the charging operation of the energy storage element is bypassed.

[0029] In one embodiment, before the constant current charging of each energy storage element, the controller controls the bypass switch and the switch, so that the power supply charges the energy storage elements with smaller remaining capacity first, and then performs constant current charging on the energy storage elements when the remaining capacity of the energy storage elements is the same.

[0030] Therefore, the charging and discharging system has the following characteristics and advantages: 1. Precise battery output voltage can be achieved through constant current charging and constant voltage discharging provided by the load unit; 2. The overall constant current charging and constant voltage discharging time is significantly shortened, which can save a large amount of charging time; 3. The battery remaining capacity of the energy storage elements is controlled to be the same or similar (e.g. less than 0.5% difference) before subsequent charging and discharging control, which can achieve energy saving effect; 4. A large number of batteries can achieve higher output voltage concentration (i.e. reduce the voltage difference between batteries) through the charging and discharging operation of the present application, so that the time required to charge the battery to a certain target voltage can be shortened.

[0031] Another object of the present application is to provide an operation method of a discharging device for discharging an energy storage element, the discharging device comprising a switch and a load unit, the switch being connected in series with the energy storage element, and the load unit being coupled to the energy storage element. The operation method comprises: (a) turning on the switch to charge the energy storage element with constant current; (b) determining whether the voltage of the energy storage element reaches a reference voltage; and (c) when the voltage reaches the reference voltage of the corresponding discharging device, enabling the load unit to charge or discharge the energy storage element at a constant voltage to a fixed voltage.

[0032] In one embodiment, the operation method further comprises: (d) charging the energy storage element with constant voltage.

[0033] In one embodiment, when the voltage of the energy storage element reaches the reference voltage, the load unit is enabled to discharge the energy storage element with constant current instead of constant voltage discharge to a fixed voltage.

[0034] Therefore, the operation method of the discharge device has the following characteristics and advantages: 1. Precise battery output voltage can be achieved by constant current charging and constant voltage discharging provided by the load unit; 2. The time of overall constant current charging and constant voltage discharging is significantly shortened, and a large amount of charging time can be saved; 3. The battery remaining capacity of the energy storage elements is controlled to be the same or similar (for example, less than 0.5% difference), and then the subsequent charging and discharging control is performed, so that energy saving effect can be achieved; 4. A large number of batteries are charged and discharged by the present application, and a higher output voltage concentration (i.e. reducing the voltage difference between the batteries) can be achieved, so that the time required to charge the batteries to a certain target voltage can be shortened.

[0035] In order to further understand the technology, means and effects adopted by the present application to achieve the predetermined purpose, please refer to the following detailed description and drawings of the present application. It is believed that the purpose, characteristics and features of the present application can be understood in depth and specifically from the drawings. However, the drawings are provided for reference and illustration only, and are not used to limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0036] Fig. 1 is a schematic waveform diagram of the existing battery charged by constant current and constant voltage;

[0037] Fig. 2 is a block diagram of the discharge device of the present application;

[0038] Fig. 3A is a circuit diagram of the first embodiment of the load unit of the discharge device of the present application;

[0039] Fig. 3B is a circuit diagram of the second embodiment of the load unit of the discharge device of the present application;

[0040] Fig. 3C is a circuit diagram of the third embodiment of the load unit of the discharge device of the present application;

[0041] Fig. 4 is a block diagram of the charge and discharge system of the present application;

[0042] Fig. 5 is a schematic waveform diagram of the energy storage element of the present application charged by constant current and discharged by constant voltage;

[0043] Fig. 6 is a schematic waveform diagram of the energy storage element of the present application charged by constant current, constant voltage and constant voltage;

[0044] Fig. 7 is a charging schematic diagram of the two energy storage elements of the present application with the same remaining capacity;

[0045] Fig. 8 is a charging schematic diagram of the two energy storage elements of the present application with different remaining capacities;

[0046] Fig. 9 is a schematic block diagram of the discharge of the energy storage element of the present application;

[0047] Fig. 10A is a flow chart of the first embodiment of the operation method of the discharge device of the present application;

[0048] Fig. 10B is a flow chart of a second embodiment of the operation method of the discharge device of the present application.

[0049] Legend 10: energy storage element 20: switch 30: load unit 40: controller 50: isolated communication element 60: power supply 70: connector 80: bypass switch 71: first connector 72: second connector 12: series branch S1: first control signal S2: second control signal Se: external control signal 301: switching element 302: resistance element 303: feedback control unit 31: second series branch Vfb: battery voltage Vref: reference voltage Sd: drive signal Pdisl: first discharge energy Pdis2: second discharge energy Sll-Sl3: step S21-S24: step DETAILED DESCRIPTION

[0050] The technical contents and detailed descriptions of the present application are explained as follows with reference to the accompanying drawings.

[0051] Referring to Fig. 2, a block diagram of the discharge device of the present application is shown. As shown in Fig. 2, the discharge device of the present application is used to discharge the energy storage element 10. The discharge device includes a switch 20, a load unit 30, a controller 40, and an isolated communication element 50.

[0052] The switch 20 is connected in series with the energy storage element 10 to form a first series branch 12. The energy storage element 10 can be an element of different energy storage forms (e.g., mechanical energy storage, electrochemical energy storage, chemical energy storage, thermal energy storage, and electric energy storage), and any element having energy storage function should be included in the scope of the present application. For example, but not limited to the present application, secondary batteries (lead-acid batteries, lithium batteries...), super capacitors, superconducting magnetic energy storage elements... Furthermore, the switch 20 is used to turn on and turn off the first series branch 12, and can be a semiconductor switch, a relay... but not limited to the present application.

[0053] The load unit 30 is connected in parallel to the first series branch 12 or the energy storage element 10. Please refer to Fig. 3B, which is a circuit diagram of a second embodiment of the load unit of the discharge device of the present application, i.e. the embodiment of the load unit 30 connected in parallel to the first series branch 12. As shown in Fig. 3B, the load unit 30 includes a switching element 301, a resistive element 302, and a feedback control unit 303. In the present application, the load unit 30 is mainly used to maintain the voltage of the energy storage element 10, and when there is excess current in the energy storage element 10, it can provide a path for discharge. Therefore, this load unit 30 can be called a constant-voltage load. Furthermore, this load unit 30 can be realized by a transistor and a feedback circuit. As shown in the embodiment of Fig. 3B, the resistive element 302 is connected in series to the switching element 301 to form a second series branch 31, and the second series branch 31 is connected in parallel to the first series branch 12. The feedback control unit 303 is connected to the switching element 301 and generates a load control signal Sd to control the on and off of the switching element 301. Incidentally, in the present application, the switching element 301 can be, for example but not limited to, a semiconductor switch, as shown in Figs. 3A-3C. However, in different embodiments, other types of switching elements can also be used, so that any switching element with on and off functions should be included in the scope of the present application.

[0054] As shown in Fig. 3B, in the present embodiment, the feedback control unit 303 is an operational amplifier, which includes two input terminals, one of which receives the measured voltage Vfb of the energy storage element 10 (hereinafter referred to as the battery voltage Vfb), and the other receives a reference voltage Vref. The feedback control unit 303 compares the battery voltage Vfb with the reference voltage Vref to control the impedance of the switching element 301. In other words, when the measured battery voltage Vfb of the energy storage element 10 reaches the reference voltage Vref, the feedback control unit 303 generates a high-level drive signal Sd to reduce the impedance of the switching element 301, thereby causing the load unit 30 to provide constant-voltage discharge operation. Alternatively, in another embodiment, when the measured battery voltage Vfb of the energy storage element 10 reaches the reference voltage Vref, the feedback control unit 303 generates a high-level drive signal Sd to reduce the impedance of the switching element 301, thereby causing the energy storage element 10 to provide constant-current discharge operation. Conversely, if the measured battery voltage Vfb of the energy storage element 10 is less than or equal to the reference voltage Vref, the feedback control unit 303 generates a low-level drive signal Sd to increase the impedance of the switching element 301, causing the load unit 30 to continuously provide constant-voltage discharge operation. Alternatively, in the corresponding constant-current discharge operation disclosed above, the energy storage element 10 continuously provides constant-current discharge operation.

[0055] In addition, since the load unit 30 generates heat when discharging at a constant voltage, the present application further provides a temperature detection of the load unit 30 and a heat sink for dissipating heat.

[0056] As shown in Fig. 3C, which is a circuit diagram of a third embodiment of the load unit of the discharge device of the present application, i.e. the load unit 30 is connected in parallel with the energy storage element 10. The major difference between the embodiment shown in Fig. 3B and the embodiment shown in Fig. 3C is that the load unit 30 shown in Fig. 3B is connected in parallel with the first series branch 12, while the load unit 30 shown in Fig. 3C is connected in parallel with the energy storage element 10. Since the circuit elements of the load unit 30 shown in Fig. 3B and Fig. 3C are the same, and the voltage determination method is the same, no further description is provided here, and please refer to the foregoing description.

[0057] In addition, besides the two embodiments shown in Fig. 3B and Fig. 3C, the discharge device can reduce the bypass switch 80, such as the embodiment shown in Fig. 3A, so that a single discharge device can also enable the load unit 30 to discharge the energy storage element 10. For specific operations, please refer to the foregoing description, and no further description is provided here.

[0058] Referring back to Fig. 2, the controller 40 is coupled to the switch 20 for controlling the switch 20, wherein the controller 40 generates a first control signal S1 for controlling the on and off of the switch 20, which will be described later.

[0059] The isolation communication element 50 is connected to the controller 40 and receives an external control signal Se, wherein the control signal Se can be a voltage signal or a current signal, which is provided by an external device, such as a computer host device, and is received by the isolation communication element 50. The controller 40 controls the switch 20 to be on according to the external control signal Se, so that the energy storage element 10 is charged at a constant current, and the load unit 30 is enabled (turned on) when the voltage of the energy storage element 10 (i.e. the foregoing battery voltage Vfb) reaches the reference voltage Vref, so that the energy storage element 10 is discharged at a constant voltage to a fixed voltage Vx, thereby achieving the charging and discharging of the energy storage element 10.

[0060] As shown in FIG. 5, which is a schematic waveform diagram of the energy storage device of the present application charging at a constant current and discharging at a constant voltage. Referring to FIG. 2, in this embodiment, between time tl and time t2, the controller 40 controls the power supply 60 to charge the energy storage device 10 according to the external control signal Se. Thus the controller 40 provides the first control signal S1 to turn on the switch 20. During this charging stage, the power supply 60 provides energy, power to the energy storage device 10 through the connector 70 to charge the energy storage device 10 at a constant current. Thus, the voltage of the energy storage device 10 gradually increases. Until the voltage of the energy storage device 10 reaches a reference voltage (as described above in FIG. 3B or FIG. 3C, which is not repeated here), the load unit 30 is enabled to discharge at a constant voltage.

[0061] It is worth mentioning that according to the above description, the load unit 30 discharges at a constant voltage at time t2 of FIG. 5. However, a standby (or idle) time can be further introduced between time t2 and time t3, that is, during the standby time, the energy storage device 10 is not charged or discharged. At the end of the standby time, that is, at time t3, the load unit 30 is enabled to discharge at a constant voltage. In this way, a buffer can be provided between the constant current charging and the constant voltage discharging to achieve stable and accurate constant voltage discharging operation. During the constant current charging process, the voltage of the energy storage device 10 is less than the full charge voltage of the energy storage device 10. For example, if the full charge voltage of the energy storage device 10 is 4.2 volts, then at time t2, the voltage of the energy storage device 10 (the maximum voltage during the constant current charging process) will be less than 4.2 volts.

[0062] Then, between time t3 and time t4, the controller 40 compares the battery voltage Vfb of the energy storage device 10 with the reference voltage Vref (as shown in FIG. 3B or FIG. 3C). When the measured battery voltage Vfb of the energy storage device 10 reaches the reference voltage Vref, the feedback control unit 303 generates a high-level drive signal Sd to turn on the switch element 301, thereby enabling the load unit 30 to provide constant voltage discharge of the excess energy of the energy storage device 10 through the load unit 30. In this way, the energy storage device 10 will be discharged to a fixed voltage Vx, for example but not limited to 3.802 volts. It is worth mentioning that during the constant voltage discharging process, the energy storage device 10 is first controlled in a negative current mode, and then the negative current value is gradually increased until it approaches zero current to complete the constant voltage discharging. In addition, between time t3 and time t4, the constant current discharging can also be replaced by discharging to the target voltage Vx to end the discharging process, which is not repeated here.

[0063] At time t4, the constant voltage discharge is completed. However, due to the battery ion concentration distribution characteristics of the energy storage element 10, the voltage of the energy storage element 10 can slightly increase after the constant voltage discharge is completed. And after time t5, the quality control stage is entered, for example, but not limited to, within 6 hours (t4-t5), the voltage of the energy storage element 10 is detected. In the quality control stage, if the voltage of the energy storage element 10 is within the required range, the charging program is completed.

[0064] Please refer to FIG. 6, which is a schematic waveform diagram of the constant current charging, constant voltage charging, and constant voltage discharging of the energy storage element 10 of the present application. In the present embodiment, between time t1 and time t2, the controller 40 controls the power supply 60 to charge the energy storage element 10 according to the external control signal Se. Therefore, the controller 40 provides the first control signal S1 to control the switch 20 to be turned on. In this charging stage, the power supply 60 provides energy, power to the energy storage element 10 through the connector 70, and charges the energy storage element 10 in a constant current manner, so the voltage of the energy storage element 10 gradually increases. Until time t2, the power supply 60 charges the energy storage element 10 in a constant voltage manner. Until the voltage of the energy storage element 10 reaches the reference voltage (please refer to the foregoing description of FIG. 3B or FIG. 3C, which is not repeated here), the load unit 30 enables the constant voltage discharge. In addition, between time t4 and time t5, the constant current discharge can also be replaced, that is, when the voltage of the energy storage element 10 reaches the reference voltage, the energy storage element 10 provides the constant current discharge operation, and the discharge process ends when the target voltage Vx is discharged. This is not repeated here.

[0065] It is worth mentioning that according to the foregoing description, at time t3 of FIG. 6, the constant voltage discharge of the load unit 30 can be performed. However, a standby (or idle) time can be further introduced between time t3 and time t4, that is, during the standby time, the energy storage element 10 is not charged or discharged. And at the end of the standby time, that is, at time t4, the constant voltage discharge of the load unit 30 is enabled. In this way, a buffer can be provided between the constant current charging and the constant voltage discharging to achieve stable and accurate constant voltage discharge operation.

[0066] Then, between time t4 and time t5, the controller 40 controls the battery voltage Vfb of the energy storage element 10 according to the comparison between the battery voltage Vfb of the energy storage element 10 and the reference voltage Vref (see FIG. 3B or FIG. 3C), when the measured battery voltage Vfb of the energy storage element 10 reaches the reference voltage Vref, the feedback control unit 303 generates a higher level of the driving signal Sd to reduce the impedance of the on switch element 301, thereby enabling the load unit 30, so that the excess current of the energy storage element 10 under the fixed voltage condition can be consumed by the load unit 30, providing the constant voltage discharge function. In this way, the energy storage element 10 will be discharged to a fixed voltage Vx, for example but not limited to 3.800 volts. It is worth mentioning that during the constant voltage discharge process, the energy storage element 10 is first controlled in a negative current mode, and then the negative current value is gradually increased until it approaches zero current to complete the constant voltage discharge. Alternatively, the constant voltage discharge can be replaced by the constant current discharge, that is, the energy storage element 10 is discharged to a fixed voltage Vx by providing a constant current discharge operation.

[0067] At time t5, the energy storage element 10 is discharged. However, due to the battery ion concentration distribution characteristics of the energy storage element 10, after the constant voltage discharge is completed, the voltage of the energy storage element 10 may slightly increase. And at time t6, enter the quality control stage, for example but not limited to 6 hours, the interval time from t5 to t6, the voltage of the energy storage element 10 is detected after time t6 as the basis for quality control. In the quality control stage, if the voltage of the energy storage element 10 is within the required range, the charging process is completed.

[0068] For the energy storage element 10, as shown in FIG. 2, the energy storage element 10 is charged by an external power supply 60. Furthermore, the discharge device also includes a connector 70, and the connector 70 connects the power supply 60 and the energy storage element 10. Therefore, the power supply 60 provides energy, power to the energy storage element 10 through the connector 70 to charge the energy storage element 10.

[0069] As shown in FIG. 2, the discharge device also includes a bypass switch 80. The bypass switch 80 is connected in parallel with the first series branch 12. When the bypass switch 80 is turned on and the switch 20 is turned off, the charging operation of the energy storage element 10 is bypassed, that is, the energy, power provided by the power supply 60 will no longer charge the energy storage element 10 through the switch 20, but through the bypass of the bypass switch 80. Specifically, the controller 40 generates a second control signal S2 to control the on and off of the bypass switch 80.

[0070] Please refer to FIG. 4, which is a block diagram of the charging and discharging system of the present application. As shown in FIG. 4, the charging and discharging system comprises a plurality of discharging devices 101-10N as shown in FIG. 2. Each of the discharging devices 101-10N comprises a switch 20, a load unit 30, a controller 40, an isolation communication element 50, a bypass switch 80, and two connectors 71, 72, i.e. a first connector 71 and a second connector 72. For the first discharging device 101, the first connector 71 of the first discharging device 101 is used to connect the discharging device with the power supply 60, and the second connector 72 of the first discharging device 101 is used to connect the next discharging device, i.e. the second discharging device 102. For the second discharging device 102, the first connector 71 of the second discharging device 102 is used to connect the second connector 72 of the first discharging device 101, and the second connector 72 of the second discharging device 102 is used to connect the next discharging device, i.e. the third discharging device (not shown in the figure). In this way, the first connector 71 of the Nth discharging device 10N is used to connect the second connector 72 of the (N-1)th discharging device 101, thereby forming a serial power supply path.

[0071] Please refer to FIG. 7, which is a charging diagram of the present application when the remaining capacities of the two energy storage elements are the same. Take two discharging devices, i.e. the first discharging device 101 and the second discharging device 102, as an example for illustration. In this operation scenario, since the remaining capacity of the battery of the energy storage element 10 of the first discharging device 101 (which can be represented by SOC, state of charge of the battery) is similar to or not much different from the remaining capacity of the battery of the energy storage element 10 of the second discharging device 102, the energy storage elements 10 of the two discharging devices 101, 102 can be simultaneously controlled for charging and discharging. As shown in FIG. 7, the controllers 40 of the discharging devices 101, 102 respectively control the switches 20 to be turned on, and thus the energy, power provided by the power supply 60 is directly and sequentially used to charge the energy storage elements 10 of the first discharging device 101 and the second discharging device 102, i.e. the energy, power provided by the power supply 60 flows through the first power supply path P1 to charge the two energy storage elements 10. As for the discharging operation of the energy storage elements 10 of the discharging devices 101, 102, please refer to the foregoing description, which will not be repeated here.

[0072] Please refer to Fig. 8, which is a charging schematic diagram of two energy storage elements with different remaining capacities. Take two discharging devices, i.e., the first discharging device 101 and the second discharging device 102, as examples for illustration. Unlike the operation scenario of Fig. 7, the battery remaining capacity of the energy storage element 10 of the first discharging device 101 is significantly different from that of the energy storage element 10 of the second discharging device 102, i.e., the energy storage capacities of the two energy storage elements 10 are unbalanced. For example, the battery remaining capacity of the energy storage element 10 of the first discharging device 101 is much lower than that of the energy storage element 10 of the second discharging device 102. If the charging is performed in the operation mode disclosed in Fig. 7, although the two energy storage elements 10 will reach the same battery voltage after a period of time, it is obvious that when the energy storage element 10 of the second discharging device 102 reaches the battery voltage first, the energy storage element 10 of the first discharging device 101 is still being charged. Therefore, the excess current of the energy storage element 10 of the second discharging device 102 will be released to the load unit 30 of the second discharging device 102 first, which will cause the second discharging device 102 to have higher energy consumption.

[0073] Therefore, in order to solve the problem of higher energy consumption caused by the significantly different battery remaining capacities, the energy storage element 10 of the first discharging device 101 with the smaller battery remaining capacity is charged first, and when the battery remaining capacity is the same as or similar to that of the other energy storage element 10 (i.e., the energy storage element 10 of the second discharging device 102), the energy storage elements 10 of the two discharging devices 101, 102 are simultaneously charged and discharged. In this way, the energy consumption can be reduced.

[0074] For example, as shown in Fig. 8, the controller 40 of the first discharging device 101 controls the switch 20 of the first discharging device 101 to be turned on and controls the bypass switch 80 of the first discharging device 101 to be turned off, and the controller 40 of the second discharging device 102 controls the switch 20 of the second discharging device 102 to be turned off and controls the bypass switch 80 of the second discharging device 102 to be turned on. In this way, the energy or power provided by the power supply 60 will only charge the energy storage element 10 (low capacity) of the first discharging device 101, but not the energy storage element 10 (high capacity) of the second discharging device 102, i.e., the energy or power provided by the power supply 60 flows through the second power path P2. When the battery remaining capacity of the energy storage element 10 of the first discharging device 101 is the same as or similar to that of the other energy storage element 10 (i.e., the energy storage element 10 of the second discharging device 102), the energy storage elements 10 of the two discharging devices 101, 102 are simultaneously charged and discharged, i.e., the operation scenario shown in Fig. 7, which can achieve the energy saving effect. The discharging operation of the energy storage elements 10 of the discharging devices 101, 102 can be referred to the previous description, which will not be described again here.

[0075] Therefore, if the battery remaining capacities of the energy storage elements of the plurality of discharging devices are different, the energy storage elements can receive the energy provided by the power supply 60 or bypass the energy provided by the power supply 60 by controlling the on or off of the corresponding switch 20 and the on or off of the bypass switch 80, so that the battery remaining capacities of the energy storage elements are the same or similar (e.g. less than 0.5% difference), and then the subsequent charging and discharging control is performed, so that the energy saving effect can be achieved. It is noted that since the battery remaining capacity information of the energy storage elements can be obtained, and the charging current provided by the charging time is known, the charging amount can also be accurately calculated, so that the battery remaining capacities of the energy storage elements are the same, which can also be easily achieved in the present application.

[0076] Referring to FIG. 9, which is a schematic block diagram of the discharging of the energy storage element of the present application. In addition to the present application, part of the excess energy (i.e. the first discharging energy Pdis1) of the energy storage element 10 can be discharged by the load unit 30 at a constant voltage, and part of the energy (i.e. the second discharging energy Pdis2) can be fed back to the power supply 60, so that the energy use efficiency can be increased by recycling the energy.

[0077] Referring to FIGS. 10A and 10B, which are flowcharts of the first and second embodiments of the operation method of the discharging device of the present application, respectively. As shown in FIG. 10A, the operation method includes turning on the switch to charge the energy storage element at a constant current (step S11). Then, it is determined whether the voltage of the energy storage element reaches the reference voltage (step S12). If the voltage does not reach the reference voltage, step S11 is performed. If the voltage reaches the reference voltage corresponding to the discharging device, the load unit is enabled to charge or discharge the energy storage element at a constant voltage (step S13). For specific description of the discharging device, please refer to the foregoing content, which will not be described here. The second embodiment shown in FIG. 10B is different from the first embodiment shown in FIG. 10A in that between step S21 (corresponding to step S11 of FIG. 10A) and step S23 (corresponding to step S12 of FIG. 10A), the energy storage element is further charged at a constant voltage (step S22). In the determination of step S23, if the voltage does not reach the reference voltage, step S22 is performed. If the voltage reaches the reference voltage corresponding to the discharging device, the load unit is enabled to charge or discharge the energy storage element at a constant voltage (step S24).

[0078] In summary, the present application has the following features and advantages:

[0079] 1. Precise battery output voltage can be achieved by constant current charging and constant voltage discharging provided by the load unit.

[0080] 2、The time for charging the batteries with similar characteristics in the same batch to a fixed voltage range is shortened.

[0081] 3、The charging switch 20 and the bypass switch 80 are first controlled to charge the energy storage elements with low power, and when the remaining capacity of the energy storage elements is the same or similar (for example, less than 0.5% difference), the entire string of batteries is subjected to subsequent charging and discharging control, thereby achieving energy-saving effect.

[0082] 4、The operation method for charging and discharging a large number of batteries according to the present application can achieve the same or higher output voltage concentration (i.e., reduce the voltage difference between the batteries) in a shorter time compared to the traditional CC charging plus CV charging process, thereby shortening the time required for charging the batteries to a fixed voltage.

[0083] The above description is only a detailed description of the preferred embodiments of the present application and the accompanying drawings, and the features of the present application are not limited thereto. The scope of the present application should be determined by the following claims, and any embodiments similar to the claims of the present application and similar changes should be included in the scope of the present application. Any changes or modifications easily thought of by those skilled in the art within the scope of the present application can be covered by the following claims.

Claims

1. A discharging device, comprising: a storage element; and a load unit coupled to the storage element; wherein the storage element is charged at a constant current, and when a voltage of the storage element reaches a reference voltage, the load unit is enabled to discharge the storage element at a constant voltage to a fixed voltage.

2. The discharging device of claim 1, wherein the discharging device further comprises: a switch connected in series with the storage element to form a first series branch, wherein the load unit is connected in parallel with the first series branch or the storage element; a controller coupled to the switch; and an isolated communication element connected to the controller and receiving an external control signal; wherein the controller controls the switch to be turned on according to the external control signal, so that the storage element is charged at a constant current.

3. The discharging device of claim 1, wherein the storage element is charged by a power supply.

4. The discharging device of claim 1, wherein after the storage element is charged at a constant current for a period of time, when the voltage of the storage element reaches the reference voltage corresponding to the discharging device, the load unit is enabled to maintain the storage element charged or discharged at a constant voltage to the fixed voltage.

5. The discharging device of claim 1 or claim 4, wherein when the voltage of the storage element reaches the reference voltage, the load unit is enabled to discharge the storage element at a constant current instead of at a constant voltage to the fixed voltage.

6. The discharging device of claim 1, wherein during the constant current charging, the voltage of the storage element is less than a full charge voltage of the storage element.

7. The discharging device of claim 2, wherein the load unit comprises: a switching element; a resistive element connected in series with the switching element; and a feedback control unit connected to the switching element and generating a load control signal to control the switching element.

8. The discharging device of claim 7, wherein the feedback control unit receives the voltage of the storage element and the reference voltage, and compares the voltage with the reference voltage; wherein the load control signal controls an impedance of the switching element, so that the voltage of the storage element is maintained at a constant value.

9. The discharging device of claim 2, further comprising: a bypass switch connected in parallel with the first series branch; wherein when the bypass switch is turned on and the switch is turned off, the charging operation of the storage element is bypassed.

10. A charging and discharging system, comprising: a plurality of discharging devices and a plurality of storage elements connected in series with each other, each of the discharging devices being used to discharge each of the storage elements, each of the discharging devices comprising: a switch connected in series with the storage element to form a first series branch; a load unit connected in parallel with the first series branch or the storage element; a controller coupled to the switch; and an isolated communication element connected to the controller and receiving an external control signal; ​ ​ wherein each of the controllers controls the switch to turn on to cause the energy storage element to be charged at a constant current, and to enable the load unit to cause the energy storage element to be discharged at a constant voltage to a fixed voltage when the voltage of the energy storage element reaches a reference voltage.

11. The charging and discharging system of claim 10, wherein the energy storage element is charged by a power supply.

12. The charging and discharging system of claim 10, wherein after each of the energy storage elements is charged at a constant current for a period of time, the load unit is enabled to cause each of the energy storage elements to be charged or discharged at a constant voltage to maintain the voltage at the fixed voltage when the voltage of each of the energy storage elements reaches the reference voltage corresponding to the discharging device.

13. The charging and discharging system of claim 10 or 12, wherein the load unit is enabled to cause each of the energy storage elements to be discharged at a constant current to replace discharging at a constant voltage to the fixed voltage when the voltage of each of the energy storage elements reaches the reference voltage.

14. The charging and discharging system of claim 11, wherein each of the discharging devices further comprises: two connectors, one of which connects the power supply and the energy storage element, and the other of which connects another of the discharging devices.

15. The charging and discharging system of claim 10, wherein each of the load units comprises: a switch element; a resistive element connected in series with the switch element; and a feedback control unit connected to the switch element and generating a load control signal to control the switch element.

16. The charging and discharging system of claim 15, wherein the feedback control unit receives the voltage of the energy storage element and the reference voltage, and compares the voltage with the reference voltage; wherein the load control signal controls the impedance of the switch element to cause the voltage of each of the energy storage elements to be maintained at a constant value.

17. The charging and discharging system of claim 11, wherein each of the discharging devices further comprises: a bypass switch connected in parallel with the first series branch; wherein the bypass switch is used to bypass the charging operation of the energy storage element when the bypass switch is turned on and the switch is turned off; wherein before each of the plurality of energy storage elements is charged at a constant current, each of the controllers controls each of the bypass switches and each of the switches to cause the power supply to charge the energy storage elements with smaller remaining capacity first until the plurality of energy storage elements have the same remaining capacity, and then the plurality of energy storage elements are charged at a constant current.

18. An operating method of a discharging device for discharging an energy storage element, the discharging device comprising a load unit coupled to the energy storage element, the operating method comprising: (a) causing the energy storage element to be charged at a constant current; (b) determining whether the voltage of the energy storage element reaches a reference voltage; and (c) enabling the load unit to cause the energy storage element to be discharged at a constant voltage to a fixed voltage when the voltage reaches the reference voltage corresponding to the discharging device.

19. The operating method of a discharging device of claim 18, wherein between step (a) and step (b), further comprising: ​ ​ (d) performing constant-voltage charging on the energy storage element.

20. The method of operating a discharge device according to claim 18 or 19, wherein the load unit is enabled when the voltage of the energy storage element reaches the reference voltage, causing the energy storage element to discharge at a constant current instead of at a constant voltage to the fixed voltage.

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