Method for supplying constant power to an energy storage element and constant power / current output power supply

Abstract

The present invention provides a power supply method and power supply device that significantly reduce the charging time of secondary batteries. [Solution] A constant power supply method that enables the supply of a constant power for charging an energy storage element consisting of an electric double-layer capacitor, wherein the charging voltage applied to the energy storage element is detected, and the current value to be supplied to the energy storage element at that time is determined based on both a predetermined power supplied to the energy storage element and the charging voltage, and the number of constant current sources that supply a constant power to the energy storage element from among a plurality of constant current sources 100 is changed in steps based on the determined current value, thereby always supplying a constant power during the charging of the energy storage element, and the output current value corresponding to the required current value shown on the horizontal axis of a characteristic diagram in which the value supplied to the energy storage element is on the horizontal axis and the applied voltage is on the vertical axis becomes larger, and the output current value corresponding to the required current value shown on the horizontal axis becomes smaller.

Description

Technical Field

[0001] The present invention relates to a constant power supply method for a power storage element and a constant power and current output power supply that are particularly applicable to an electric double layer capacitor (electric double layer condenser) as a physical secondary battery.

Background Art

[0002] Conventionally, a constant voltage power supply for driving a load such as a motor and a constant current power supply for lighting a lighting fixture such as an LED at a constant illuminance are known. The general mechanism of this circuit is as follows. FIG. 6 is a block diagram of a conventional constant voltage power supply. FIG. 7 is a voltage-current characteristic diagram of the constant voltage power supply shown in FIG. 6. Here, FIG. 7 shows a case where the power is the same but the output voltage is different. The broken line is an operation example when the output exceeds the power supply allowable value.

[0003] In the definition on an electric circuit, a constant voltage power supply is a power supply that continuously supplies the same value of voltage regardless of what load is connected. For example, whether the load is 0.1 Ω (ohm) or 100 Ω, if it is a 10 V constant voltage power supply, originally, for a 0.1 Ω load, a current of about 100 A (ampere) is supplied, and the output power is 1,000 W (watt), and for a 100 Ω load, the output current should be 0.1 A and the output power should be 10 W.

[0004] However, in reality, similar to the explanation of the constant current power supply described later, there are limitations on the current value and power value that the power supply can output, and it can be seen that it is very difficult to realize a constant voltage power supply that can supply a voltage of 10 V (volt) in the range of 0.1 Ω to 100 Ω.

[0005] Also, the general mechanism of the above-described constant current circuit is as follows. FIG. 8 is a block diagram of a conventional constant current power supply. FIG. 9 is a voltage-current characteristic diagram of the constant current power supply shown in FIG. 8. Here, FIG. 9 shows a case where the power is the same but the output current is different. The broken line is an operation example when the output exceeds the power supply allowable value.

[0006] In electrical circuit definitions, a constant current power supply is a power supply that can continuously supply the same value of current regardless of the load connected to it. For example, a constant current power supply that supplies a current of 10A whether the load is 0.1Ω or 100Ω will have an output voltage of 1V and an output power of 10W with a 0.1Ω load, but with a 100Ω load, the output voltage will be calculated to be 1,000V and the output power 10,000W.

[0007] However, in reality, due to the internal control constraints of the power supply, specifically the maximum output power, it is extremely difficult to create a power supply capable of supplying a 10A current in the 0.1Ω to 100Ω range, as both the output power and output voltage range are too wide. In addition, most commercially available power supplies have a rated output power of 100W or less, and anything above that output or at non-standard voltages is usually a custom-made product.

[0008] Constant voltage power supplies are commonly used in electronic circuits, and constant current power supplies are used in LED lighting devices, etc. These power supplies are generally well-known and widely understood. (See, for example, Patent Documents 1 and 2). [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2019-056982 [Patent Document 2] Japanese Patent Publication No. 2015-029399 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] One type of power source load is a rechargeable battery, which is a secondary battery capable of being charged and discharged. Currently, when charging such batteries, it is common to use a constant current power supply and a constant voltage power supply individually or in combination. In many cases, the power supply operates as a constant current power supply in the initial stages of charging, supplying a preset current, and then switches to a constant voltage power supply to supply a preset voltage as charging progresses.

[0011] However, as mentioned above, constant current charging has the limitation that the power supply can only supply very little power when the output voltage is low. Therefore, when charging high-voltage batteries, since the output power of the power supply = current × voltage, if the maximum current value is fixed, when the load resistance is low and the output voltage of the power supply is low, the output current value of the power supply is limited, which restricts the output power and results in an unnecessarily long charging time.

[0012] This problem stems from the fact that, because a constant current source inherently has the basic function of supplying a constant current regardless of the load connected, it outputs only a preset current even under light load conditions, resulting in reduced power output.

[0013] The above description will now be explained in detail. The charging method for rechargeable batteries described above is a charging method that is often seen in the charge control of nickel-cadmium and nickel-metal hydride batteries. More specifically, it is a charging method that is designed to charge the battery at a current value that matches the characteristics of the battery in question during the initial stages of charging, and then, after a certain amount of charging has progressed, to a voltage value that is below the allowable current value of the power supply and rechargeable battery even at a constant voltage, and to charge the battery until it reaches a voltage value that is fully charged. As mentioned above, this is a charging method that is often seen in charge control elements for nickel-cadmium and nickel-metal hydride batteries.

[0014] However, in the case of rechargeable batteries that require high-current charging to shorten charging time, which are likely to be commercialized in the future, or in the case of energy storage devices such as large-capacity electric double-layer capacitors, where there are no constraints on the charging current due to the operating principle, but the current value is determined by structural constraints, the charging method described above has the drawback that if the current value is determined by the constraints of the charging power supply side as mentioned above, it will take a long time to fully charge due to the upper limit of the charging current value when the voltage is low.

[0015] For example, consider a constant current power supply with an output of 100W, and use it to charge an object to be charged. In this case, since the output is 100W, it is usually assumed that a current of 100A will be output if the output voltage is 1V, a current of 50A will be output if the output voltage is 2V, and a current of 33.3A will be output if the output voltage is 3V.

[0016] However, in reality, because the current value is fixed from the beginning, no more current is supplied, and therefore the charging time required is far longer than what would be calculated from the output power value of the charging power supply.

[0017] Furthermore, when using a low voltage such as AC100V, the allowable current is generally limited to around 10A. Therefore, when the charging voltage is low at the beginning of charging, the power that can be supplied with a constant current—that is, the power that can actually be used for charging in this case is very small compared to 1000W—resulting in very inefficient charging.

[0018] The object of the present invention is to provide a method for supplying constant power to an energy storage element and a constant power / current output power supply that is particularly applicable to electric double-layer capacitors (electric double-layer condensers) as physical secondary batteries. [Means for solving the problem]

[0019] In order to solve the above-mentioned problems, the method for supplying constant power to an energy storage element according to claim 1 of the present invention is: A constant power supply method that enables supply of a constant power for charging a power storage element composed of an electric double layer capacitor, detects a charging voltage applied to the power storage element, and determines a current value flowing into the power storage element at that time based on both a predetermined power supplied to the power storage element and the charging voltage, By gradually changing the number of constant current sources that supply a constant power to the power storage element among a plurality of constant current sources based on the determined current value, a constant power is always supplied to the power storage element during charging of the power storage element, and Regarding the manner of the stepwise change of the current value flowing from the constant current source into the power storage element during charging of the power storage element, in a correlation characteristic diagram of output voltage - required current value with the value flowing into the power storage element during charging of the power storage element on the horizontal axis and the voltage applied to the power storage element on the vertical axis, as the output voltage value indicated by the vertical axis of the correlation characteristic diagram gradually increases, the output current value corresponding to the required current value indicated by the horizontal axis gradually decreases.

Advantages of the Invention

[0020] According to the present invention, it is possible to provide a constant power supply method and a constant power - current output power source that are particularly excellent and applicable to a power storage element.

Brief Description of the Drawings

[0021] [Figure 1] It is a block diagram of a constant power - current output power source according to a first embodiment of the present invention. [Figure 2] It is a voltage - current characteristic diagram of the constant power - current output power source shown in FIG. 1. [Figure 3] It is a block diagram of a constant power - current output power source according to a second embodiment of the present invention. [Figure 4] It is a voltage - current characteristic diagram of the constant power - current output power source according to the second embodiment shown in FIG. 3, and a voltage - current characteristic diagram of the constant power - current output power source according to a modification of the second embodiment shown in FIG. 5. [Figure 5] This is a block diagram of a constant power and current output power supply according to a modified example of the second embodiment of the present invention. [Figure 6] This is a block diagram of a conventional constant voltage power supply. [Figure 7] This is a voltage-current characteristic diagram of the constant voltage power supply shown in FIG. 6. [Figure 8] This is a block diagram of a conventional constant current power supply. [Figure 9] This is a voltage-current characteristic diagram of the constant current power supply shown in FIG. 8.

Embodiments for Carrying Out the Invention

[0022] Hereinafter, a constant power and current output power supply according to the first embodiment of the present invention will be described based on the drawings. Regarding the name of the present invention, although it can also be referred to as a "constant power power supply by current output", in this application, it shall be unified to the term "constant power and current output power supply". Also, in the description of each of the following embodiments and their modified examples, the "electric double layer capacitor" as a secondary battery is also referred to as an "electric double layer capacitor", but in this application, it shall be unified to the former term.

[0023] Also, in the following description, including the first and second embodiments and their modified examples, a power storage device using a large-capacity electric double layer capacitor, which is a physical secondary battery among secondary batteries, as a load target for supplying constant power by current control according to the present invention will be described. Therefore, in the following description, for the sake of facilitating the understanding of the invention, the term "load" will be described by substantially replacing it with the terms "secondary battery", "(large-capacity) electric double layer capacitor", and "secondary battery such as lithium ion".

[0024] In the embodiments and modifications thereof of the present invention, the term "large-capacity electric double-layer capacitor" can currently be defined as a capacitor having a capacitance of several thousand farads (F) to several hundred thousand farads (F). However, in the future, electric double-layer capacitors with larger capacitances that can handle higher voltages will naturally be developed and widely commercialized through technological innovation. Therefore, electric double-layer capacitors with capacitances exceeding the above definition will also be included in this "large-capacity electric double-layer capacitor." In the following explanation, the term "large-capacity electric double-layer capacitor" as an energy storage element will be abbreviated as "secondary battery" as appropriate.

[0025] Figure 1 is a block diagram of a constant power / current output power supply according to the first embodiment of the present invention. Figure 2 is a voltage / current characteristic diagram of the constant power / current output power supply shown in Figure 1.

[0026] A constant power / current output power supply according to the first embodiment of the present invention (hereinafter referred to as "first constant power / current output power supply" or simply "constant power / current output power supply") is a charging device for an energy storage device using an electric double-layer capacitor, and is excellent for supplying a constant power to the energy storage device. In particular, it can exhibit remarkable effects not seen in conventional devices when charging a secondary battery using a large-capacity electric double-layer capacitor.

[0027] The first constant power / current output power supply 10 includes a plurality of constant current power supplies 100 (100-1, 100-2, ... 100N), a group of constant current source operation changeover switches 150 consisting of a plurality of switches for starting and stopping each of the plurality of constant current power supplies 100 in order to operate or stop each of the plurality of constant current power supplies 100, and a current value determination / switch switching control unit 130 that controls the switching of the plurality of switches of the constant current source operation changeover switch group 150 in order to supply a constant power to the secondary battery 70.

[0028] The first constant power / current output power supply 10 will be described in more detail below. Each switch in the constant current source operation changeover switch group 150 is provided in correspondence to each of the multiple constant current sources 100 (100-1, 100-2, ... 100-N) consisting of N (where N is a natural number of 2 or more) and the operation of each constant current source 100 (100-1, 100-2, ... 100-N) is controlled by turning each switch on or off.

[0029] Furthermore, the first constant power / current output power supply 10 has a full-wave rectification and smoothing circuit 140 between the constant current source operation changeover switch group 150 and the AC power supply 50, so that the AC input from the AC power supply 50 is full-wave rectified and smoothed and then fed into each switch SW1, SW2, ... SWN of the constant current source operation changeover switch group 150.

[0030] Each of the N constant current sources 100 has a configuration similar to the conventional one shown in Figure 8, but has a current control function, and the circuit itself is divided into a primary side and a secondary side by a transformer. In Figure 1, these configurations are shown as an insulating separation section 126 in the lower right corner of the figure to facilitate understanding of the invention.

[0031] The primary side 110 of the transformer is equipped with an amplification unit 111 and a control function unit 112. The current supplied from the AC power supply 50 is transmitted to the primary side 110 of the transformer via the full-wave rectification and smoothing circuit 140 and, in this embodiment, a high-speed switching element 115 consisting of a MOSFET. In this embodiment and other embodiments, the MOSFET, as the high-speed switching element, plays the role of converting the current, which has been full-wave rectified and smoothed from the AC input, back into a pulsed AC wave.

[0032] On the other hand, the secondary side 120 of the transformer is connected to the secondary battery 70 to be charged via a full-wave rectifier, smoothing, and step-up / step-down circuit 127 consisting of a rectifier diode 122, a capacitor, and a coil.

[0033] The power supply unit on the secondary side of the transformer includes a current value detection unit 121 that constantly measures the current supplied to the secondary battery 70, a rectifier diode 122, a voltage value comparison unit 124 that compares the output voltage value with a reference value based on the current value detected by the current value detection unit 121, an error detection unit 125 that detects errors from both the output voltage value and the reference value in the voltage value comparison unit 124, and an isolation unit 126 for transmitting the error obtained by the error detection unit 125 from the secondary side to the primary side circuit.

[0034] Furthermore, the error signal from the primary side 110 of the transformer, transmitted to the primary side via the isolation unit 126, is transmitted to the control function unit 112, which controls the operation of the high-speed switching element 115 on the primary side 110 of the transformer, by a feedback signal amplified by the amplification unit 111. The error obtained by the error detection unit 125 is constantly transmitted to the primary side 110 of the transformer while being isolated, and then fed back to the control function unit 112 via the amplification unit 111. Based on this configuration, the control function unit 112 supplies a constant current to the secondary battery 70 while minimizing the errors obtained by the voltage value comparison unit 124 and the error detection unit 125 on the secondary side 120 of the transformer.

[0035] Furthermore, when supplying current to the secondary battery 70, all predetermined current supply terminals derived from each of the N constant current sources 100 are electrically connected, and the total current supplied from the operating constant current sources 100, combined with the current supplied by the switch in the connected state, flows into the secondary battery 70 for charging.

[0036] The current value determination / switch switching control unit 130 includes a voltage value detection unit 131, a current value determination / switch state update unit, and a switch control signal transmission unit 133. The voltage value detection unit 131 constantly detects the output voltage from the constant current power supply 100 applied to the secondary battery 70 while the secondary battery 70 is being charged. The current value determination / switch switching update unit 132 calculates the required current value corresponding to the preset output power of the first constant power / current output power supply 10 based on the detected voltage value detected by the voltage value detection unit 131. It also constantly performs calculations during the charging of the secondary battery 70 to selectively switch the number of constant current sources 100 necessary to achieve the output current value closest to the required current value calculated by the current value determination / switch state update unit, and to stop the remaining constant current sources 100 that do not need to be operated to set the power supplied to the secondary battery 70 to a predetermined value. Furthermore, the switch control signal sending unit 133 sends a switch control signal to the constant current source operation switching switch group 150 that selectively specifies and transmits the switch that should be operated at all times during charging, based on the results calculated by the current value determination / switch state update unit.

[0037] As a result, the first constant power / current output power supply 10 is configured such that, in a correlation characteristic diagram of output voltage and required current value, where the required current value calculated by the current value determination / switch switching update unit 132 of the current value determination / switch switching control unit 130 is on the horizontal axis and the output voltage detected by the voltage value detection unit 131 of the current value determination / switch switching control unit 130 is on the vertical axis, the current value determination / switch switching control unit 130 switches each switch of the constant current source operation switching switch group 150 such that (when this correlation characteristic diagram is created as shown in Figure 2) the output current value corresponding to the required current value shown on the horizontal axis decreases in stages as the output voltage value shown on the vertical axis of the correlation characteristic diagram increases in stages.

[0038] Based on the above configuration, the first constant power / current output power supply 10 according to this embodiment has the first characteristic that it functions so that the power supplied to the secondary battery 70 during charging is always constant.

[0039] Furthermore, a second feature of the first constant power / current output power supply 10 according to this embodiment is that it detects the voltage value applied to the secondary battery 70 and uses this detection signal to control the power supplied from the power supply to the secondary battery 70 so that it approximates a step wave shape that is constant at all times.

[0040] Furthermore, a third feature of the first constant power / current output power supply 10 according to this embodiment is that, for example, when charging a secondary battery 70, it starts charging with a high current value and a low voltage value while keeping the power supplied to the secondary battery 70 constant, and during the charging process, the current value determination / switch switching control unit 130 gradually switches the switches of each constant current source 100 from on to off, thereby gradually decreasing the current value and gradually increasing the voltage value.

[0041] Furthermore, in the first constant power / current output power supply 10 according to this embodiment, since the secondary battery 70 is an electric double-layer capacitor as a physical secondary battery 70, the amount of charge uniquely corresponds to the voltage value mentioned above. Therefore, power can be supplied while always accurately knowing the amount of charge of the electric double-layer capacitor as a secondary battery 70.

[0042] In other words, when the voltage is low, a large current is suddenly supplied to the secondary battery 70 to rapidly charge the electric double-layer capacitor. As the electric double-layer capacitor approaches full charge, the voltage increases, and accordingly, the current supplied to the electric double-layer capacitor is gradually reduced, providing a constant power supply while efficiently charging the capacitor.

[0043] Figure 2 is a voltage-current characteristic diagram of the first constant power / current output power supply 10 shown in Figure 1, and shows the correlation between the output current value and output voltage value of the first constant power / current output power supply 10 according to this embodiment when the first constant power / current output power supply 10 charges a secondary battery 70, which is an example of a load target. Below, the third characteristic feature of this embodiment described above will be explained in more detail based on this figure.

[0044] In the first embodiment, as shown in Figure 1, the explanation assumed that there were N constant current sources (where N is a natural number of 2 or more). However, for the sake of ease of understanding, in Figure 2, we will explain a specific example where N=6, i.e., there are 6 constant current sources. Of course, the number N of constant current sources 100 is not limited to 6 as shown in Figure 2, but as mentioned above, any natural number of 2 or more is included within the scope of the present invention.

[0045] In Figure 2, as described above, the horizontal axis represents the current value of the first constant power / current output power supply 10, and the vertical axis represents the voltage value. The process of charging an electric double-layer capacitor (hereinafter simply referred to as "secondary battery 70"), which has a charge level of zero, will be explained.

[0046] When charging the secondary battery 70 from a state where it is completely discharged and has zero charge or close to that state, the current value determination / switch switching control unit 130 turns on (conducts) all of the switches of the constant current source 100 (100-1, ... 100-N, in this case N=6).

[0047] Then, a total current of a6 amperes (A) is supplied from each of the six constant current sources 100 to the secondary battery 70 to be charged. Simultaneously, the voltage value detection unit 131 of the current value determination / switch switching control unit 130 continuously detects the voltage supplied to the secondary battery 70 by the first constant power / current output power supply 10 during charging. In accordance with this, the first constant power / current output power supply 10 continues to supply the secondary battery 70 with a total current of a6 amperes (A) from the six constant current sources 100.

[0048] Next, when the voltage detected by the voltage detection unit 131 rises to b1 volts (V), the current value determination / switch switching control unit 130 turns off (de-conducts) one of the six switches and continues to supply the remaining five constant current sources 100 with a total current a5 amperes (A) to the secondary battery 70.

[0049] Next, when the voltage detected by the voltage detection unit 131 rises to b2 volts (V), the current value determination / switch switching control unit 130 turns off (deactivates) two of the six switches, and continues to supply the remaining four constant current sources 100 with a total current a4 amperes (A) to the secondary battery 70.

[0050] Next, when the voltage detected by the voltage detection unit 131 rises to b3 volts (V), the current value determination / switch switching control unit 130 turns off (deactivates) three of the six switches, and continues to supply the remaining three constant current sources 100 with a total current of a3 amperes (A) to the secondary battery 70.

[0051] Next, when the voltage detected by the voltage detection unit 131 rises to b4 volts (V), the current value determination / switch switching control unit 130 turns off (deactivates) four of the six switches, and continues to supply the remaining two constant current sources 100 with a total current of a2 amperes (A) to the secondary battery 70.

[0052] Next, when the voltage detected by the voltage detection unit 131 rises to b5 volts (V), the current value determination / switch switching control unit 130 turns off (deactivates) five of the six switches, and continues to supply a1 amperes (A) to the secondary battery 70 from the remaining constant current source 100.

[0053] Then, when the voltage detected by the voltage detection unit 131 rises to b6 volts (V), it is determined that the battery is fully charged and charging is complete, and all six switches are turned off (de-conductive). This completes the charging operation of the secondary battery 70.

[0054] Furthermore, since the present invention is a first constant power / current output power supply 10, it continuously supplies this power to the secondary battery 70 so as to always maintain a constant power of a6×b1=a5×b2=a4×b3=a3×b4=a2×b5=a1×b6=P. Note that the explanation based on Figure 2 above assumed N=6, but the same applies when N is any other natural number greater than or equal to 2.

[0055] In the first embodiment described above, it is preferable to set upper and lower limits on the predetermined power supplied by the first constant power / current output power supply 10 to the secondary battery 70, which is the load, and to provide a certain margin in the power value supplied by the first constant power / current output power supply 10 so that the stepped correlation output characteristics of the current value and voltage value shown in Figure 2 always fall within the range between the upper and lower limits of the predetermined power supply. This is considered preferable for realizing the first constant power / current output power supply 10 in practice.

[0056] In short, in the case of the first embodiment, it should be understood that any power supply having the characteristic of being controlled so that the amount of power output remains constant within the constraints of the power supply side is included in this embodiment, and by extension, the scope of the present invention.

[0057] As explained above, in the first embodiment, when performing power supply control, the following routine is constantly repeated to exhibit the characteristics of the first constant power / current output power supply 10, which is a special effect of the step wave approximation.

[0058] Specifically, the first constant power / current output power supply 10 according to the first embodiment is characterized by having a plurality of constant current sources 100, a current value determination / switch switching control unit 130 for controlling the operation and stopping of each constant current source 100, and a group of constant current source operation switching switches 150, and in order to control the power supply including these, the following routine is constantly repeated. (Step 1) The output voltage of the first constant power / current output power supply 10 is detected, and the current output power is determined. (Step 2) Determine the current value that should be supplied from the first constant power / current output power supply 10 to the secondary battery 70 corresponding to the voltage value detected by the first constant power / current output power supply 10 at that time. (Step 3) Based on the results of Step 2, determine which switch should be activated in order to operate the constant current source 100 that satisfies the aforementioned current value. (Step 4) The switch control signal sending unit 133 sends an SW control signal corresponding to the switch determined in Step 3, and switches the switches so that only the necessary switches among the switches of the constant current source operation switching switch group 150 remain conductive, thereby updating the state of the switches. (Step 5) By repeating the above operations, the step waveform in the voltage-current output characteristics of the first constant power / current output power supply 10 is brought to a predetermined position at that time.

[0059] Next, a constant power / current output power supply according to a second embodiment of the present invention will be described with reference to the drawings. Figure 3 is a block diagram of the constant power / current output power supply according to the second embodiment of the present invention. Figure 4 is a voltage / current characteristic diagram of the constant power / current output power supply according to the second embodiment shown in Figure 3, and Figure 5 is a voltage / current characteristic diagram of the constant power / current output power supply shown in Figure 5.

[0060] The second constant power / current output power supply 20 according to the second embodiment of the present invention (hereinafter referred to as "second constant power / current output power supply 20" or simply "constant power / current output power supply 20" as appropriate) is a charging device for an energy storage device using an electric double-layer capacitor, similar to the first embodiment, and is excellent for supplying a constant power to an energy storage device using a large-capacity electric double-layer capacitor.

[0061] The second constant power / current output power supply 20 will be described below. Parts common to the first constant power / current output power supply 10 according to the first embodiment will be omitted from the description as appropriate. Furthermore, in the following description, as with the first embodiment, the load supplied by the constant power / current output power supply 20 according to the present invention will be described as the electric double-layer capacitor of the secondary battery 70 (hereinafter simply referred to as "secondary battery 70" as appropriate).

[0062] A more detailed description of the configuration of the second constant power / current output power supply 20 is given below. The constant power / current output power supply 20 is electrically isolated into a primary and secondary side by a transformer.

[0063] The primary side 210 of the transformer is equipped with an amplification unit 211 and a control function unit 212. The current supplied from the AC power supply 50 is transmitted to the primary side 210 of the transformer via a full-wave rectification and smoothing circuit 240. The secondary side 220 of the transformer is equipped with a full-wave rectification, smoothing function and current value control function unit 227 consisting of a diode, capacitor, and coil, and is connected to the secondary battery 70 so that the current supplied to the secondary battery 70 can be varied as described above.

[0064] The primary side 210 of the transformer has an amplification unit 211 that amplifies the error signal transmitted to the primary side by the isolation unit 226 shown on the secondary side in Figure 3, and a control function unit 212 that controls the current flowing through the primary side 210 of the transformer using the feedback signal amplified by the amplification unit 211. In addition, the primary side 210 of the transformer is provided with a number of tap switching terminals 250 (Tp1, Tp2, ... TpN) (in Figure 3, five tap switching terminals 250 are shown as an example), and a number of tap switching switches 260 (TSW1, TSW2, ... TSWN) corresponding to each terminal.

[0065] The power supply section of the secondary side 220 of the transformer to the secondary battery 70 is equipped with a full-wave rectification, smoothing, and current value control function section 227 consisting of a coil, diode, and capacitor, as well as a voltage / current value detection section 221 that constantly measures the voltage applied to the secondary battery 70 and the current flowing into the secondary battery 70, a power value calculation section 224 that constantly calculates the power supplied to the secondary battery 70 from the voltage and current detected by the voltage / current value detection section 221, an error calculation section 225 that compares the calculated power value with a predetermined power value, and an isolation separation section 226 for transmitting the error obtained by the error calculation section 225 from the secondary side to the primary side circuit.

[0066] The error obtained by the error calculation unit 225 is then continuously transmitted to the primary side 210 of the transformer while being isolated, and fed back to the control function unit 212 via the amplification unit 211.

[0067] The control function unit 212 minimizes the errors obtained by the voltage / current value detection unit 221, power value calculation unit 224, and error detection unit 225 of the secondary side 220 of the transformer, thereby supplying a constant current to the secondary battery 70. Specifically, the control function unit 212 uses feedback signals obtained via the isolation unit 226 and amplification unit 211 to switch the tap changer switch 260 (TSW1, TSW2, ... TSWN) to appropriately change the winding ratio of the transformer, thereby supplying a constant power to the secondary battery 70 while it is charging. To shift the output to a higher voltage / lower current side, the switch 260 is switched to a lower number of primary side windings of the transformer, and vice versa.

[0068] More specifically, the second constant power / current output power supply 20 controls the current value supplied to the charging secondary battery 70 so that, in a correlation characteristic diagram of current and voltage values ​​where the current value detected by the voltage / current value detection unit 221 is on the horizontal axis and the voltage value detected by the voltage / current value detection unit 221 is on the vertical axis, (assuming the correlation characteristic diagram is created as shown in Figure 4) the current value shown on the horizontal axis decreases as the voltage value shown on the vertical axis of the correlation characteristic diagram increases, either along an ideal continuous line or an approximate continuous line to this ideal continuous line.

[0069] In the second constant power / current output power supply 20, similar to the first embodiment, the second constant power / current output power supply 20 pre-sets upper and lower limits for the constant power supplied to the secondary battery 70. In addition, instead of an ideal continuous line, it is preferable that the control unit controls the current value to change along this allowable power band, which includes any allowable power line set within the range in which the second constant power / current output power supply 20 can supply the constant power permitted by the upper and lower limits. However, it is not necessarily limited to setting these upper and lower limits.

[0070] Based on the above configuration, the first feature of the second constant power / current output power supply 20 according to this embodiment is that it functions so that the power supplied to the secondary battery 70 during charging is always constant.

[0071] Furthermore, the second constant power / current output power supply 20 according to this embodiment detects both voltage and current during charging of the secondary battery 70, and constantly calculates the power supplied by the second constant power / current output power supply 20 to the secondary battery 70 at the time of detection by continuously integrating the detected voltage and current values. It then calculates the error by comparing this with a predetermined power value to be supplied to the secondary battery 70 and feeds the result back to the control function unit 212 via an amplifier provided in the isolated primary circuit. The second feature of the second constant power / current output power supply 20 is that it controls the power supply via the control function unit 212 of the primary circuit to eliminate the deviation between the power value calculated above and the predetermined power value to be supplied to the secondary battery 70, so that the two values ​​match.

[0072] FIG. 4 is a voltage-current characteristic diagram of the second constant power and constant current output power supply 20 shown in FIGS. 3 and 5, and shows the correlation between the output current value and the output voltage value of the second constant power and constant current output power supply 20 according to the present embodiment when charging a secondary battery 70 which is an example of a load target. Hereinafter, the operation of the present embodiment described above will be more easily explained based on this figure. In FIG. 4, as in the case of a conventional power supply, the curve is interrupted near the maximum output current and voltage. Also, in the case of a constant resistance load, the operation is the same as that of the current constant power supply at present.

[0073] In FIG. 4, as described above, the horizontal axis represents the current value of the current output power supply, and the vertical axis represents the voltage value. At the initial stage of charging the secondary battery 70, the output current value is as which is the maximum value of the current value on the horizontal axis, and the output voltage value is bs which is the minimum value of the voltage value on the vertical axis. As the charging progresses, the output current value ax decreases along the current-voltage curve shown in FIG. 4, and the output voltage value by increases along the current-voltage curve shown in FIG. 4. When the secondary battery 70 reaches the fully charged state, the output current value is af which is the minimum value on the horizontal axis, and the output voltage value is bf which is the maximum value on the vertical axis.

[0074] Here, for the sake of safety, the magnitude relationship of each output value is described as af < ax < as, bs < by < bf. Also, since the present invention is a constant power supply, as × bs = ax × by = af × bf = P (constant power).

[0075] In the same way as in the first embodiment described above, an upper limit value and a lower limit value are provided for a predetermined supply power supplied by the second constant power and constant current output power supply 20 to the secondary battery 70 which is a load, and the product of the current value and the voltage value shown in FIG. 4, that is, the power supplied by the second constant power and constant current output power supply 20 to the secondary battery 70 which is a load, is approximated to a curve with a correlation output characteristic that is always constant, that is, a curve such that the power value which is the product of the current value and the voltage value always falls within the range between the upper limit value and the lower limit value of the predetermined supply power may be used.

[0076] In other words, even if the values ​​of the voltage and current supplied by the second constant power / current output power supply 20 to the load are pre-set to have upper and lower limits, and instead of an ideal continuous line, an allowable power band is pre-set that includes an arbitrary allowable power line within the range that the second constant power / current output power supply 20 can supply to the load, and the control unit controls the current value to change so that the output changes along the allowable power curve included in this allowable power band, this is still within the scope of the present invention.

[0077] In short, even in the case of the second embodiment, as with the first embodiment, if the power supply has the characteristic of controlling the amount of power output to remain constant within the constraints of the power supply side, it should be understood that this embodiment, and by extension the present invention, is included within the scope of this embodiment.

[0078] As described above, by controlling the second constant power / current output power supply 20 according to the second embodiment of the present invention, the control method for the second constant power / current output power supply 20 as a curve approximation type can enable it to perform in accordance with the curve approximation type constant power / current output power supply characteristic diagram. Specifically, the second constant power / current output power supply 20 according to the second embodiment can perform in accordance with the curve approximation type constant power / current output power supply characteristic diagram described above by constantly repeating the routine according to the following procedure. (Step 1) The voltage and current values ​​of the power output are detected, and the power value supplied by the second constant power / current output power supply 20 to the secondary battery 70 being charged is calculated from these detected values. (Step 2) Determine the target current value from the calculated power value and the current value. (Step 3) Error information corresponding to the current value is calculated and the error information is sent to the power supply control function unit 212 via the isolation function. (Step 4) The power supply control unit 212 updates the current value flowing through the secondary transformer 220 according to the error information. That is, it instantly switches tap 250 of the primary transformer 110 from the current TpJ to a more appropriate tap TpK to move to the new current and voltage value state. By constantly repeating these routines, the power supply settles into the desired position on the constant power curve.

[0079] Next, a modified example of the second embodiment will be described. Figure 5 is a block diagram of a third constant power / current output power supply 30 according to a modified example of the second embodiment of the present invention. In the second embodiment, the primary side 210 of the transformer is provided with a number of tap switching terminals 250 (in Figure 3, as an example, five tap switching terminals 250 (Tp1,...Tp5) are shown), and a number of tap switching switches 260 (TSW1,...TSW5) corresponding to each terminal are shown.

[0080] On the other hand, in the third constant power / current output power supply 30, these tap selector switches 260 are all replaced with MOSFETs 350 (FSW1, FSW2, ... FSWN) as switching elements. Then, in order to operate the optimal MOSFET from among these MOSFETs, the control function unit 312 constantly outputs an optimal signal, similar to the second embodiment, and the gate function of the MOSFET is correctly operated by the control function. In response to this, the turns ratio of the primary and secondary sides of the transformer is changed to the optimal turns ratio, and constant power is supplied to the secondary battery 70 while it is being charged.

[0081] By utilizing the MOSFET350, further integration and high-frequency operation of the circuit are achieved. Note that the other configurations are the same as in the second embodiment, so a detailed explanation of them is omitted.

[0082] Even a constant power / current output power supply having a circuit configuration as shown in the block diagram of the third constant power / current output power supply 30 in Figure 5 can exhibit the same effects and advantages as the second embodiment shown in the circuit block diagram of Figure 3, and the second constant power / current output power supply 20 and the constant power supply method using the same based on the second embodiment shown in Figure 4.

[0083] According to the present invention as described in each of the embodiments above, it is possible to provide a charging power supply and a control method therefor that can solve the problems of the conventional charging method described above and significantly shorten the charging time compared to the conventional method.

[0084] In short, conventional charging methods for energy storage devices and their problems generally involve charging with a constant current when the device is at a low voltage, and then switching to constant voltage control when the device reaches a predetermined voltage and the current value falls below the constant current value. However, with this method, the amount of power that can be supplied to the device is very small when the voltage of the device is low, and the amount of power that can be supplied increases as the voltage rises. Therefore, there is a problem that the amount of power that can be used for charging is small in the initial stages of charging, resulting in a long charging time. This is a fundamental matter related to power supply control, and resolving this problem has been difficult, but the present invention makes it possible to solve this problem all at once.

[0085] More specifically, by focusing on the output power of the power supply, and controlling the current value to increase within the power supply's allowable range when the output voltage is low, even in constant current operation, and decreasing the current value within the power supply's allowable range when the output voltage increases, it is possible to significantly increase the power supplied to the load by increasing the current value when the voltage is low, even when using a constant current power supply with the same output power, thereby achieving a significant reduction in the charging time of the energy storage element.

[0086] Based on this idea, the inventors have conceived a method for supplying constant power to energy storage elements and a constant power / current output power supply. This method increases the output current within the power supply's tolerance range when the output voltage is low, and decreases the output current as the voltage rises, thereby controlling the power supplied to the load. This invention demonstrates significant technical merit.

[0087] The embodiments of the present invention and their effects will be described in more detail below, including various application examples for their actual use. The embodiments of the present invention described above are particularly suitable for charging large-capacity electric double-layer capacitors. Specifically, they are as follows. (1) Fast charging is possible. (2) It is possible to charge large-capacity electric double-layer capacitors.

[0088] This makes it possible, for example, when charging and driving an electric vehicle (EV), to quickly charge it for a short time, for example 10 minutes, drive around the nearby area, return, and then quickly charge it again for a short waiting period, for example 10 minutes, and drive around the nearby area again, and repeat this process.

[0089] This is because electric double-layer capacitors are physical secondary batteries. Specifically, when an electric double-layer capacitor is used as a secondary battery, it can be charged efficiently and quickly by significantly increasing the current when the voltage is low and then gradually decreasing it as the voltage rises. This is because secondary batteries are physical secondary batteries, such as electric double-layer capacitors, and it is difficult to achieve the same with chemical secondary batteries such as lithium-ion batteries.

[0090] In other words, in the case of chemical secondary batteries such as lithium-ion batteries, the current value for charging is currently determined while constantly considering the balance between heat generation and heat dissipation caused by the battery's internal resistance—which arises from chemical reactions, internal structure, and constituent materials—during the charging process.

[0091] Furthermore, in recent years, electric vehicles (EVs) equipped with lithium-ion secondary batteries are charged in a way that allows them to travel approximately 60% of the battery's capacity on a single charge, regardless of the destination or purpose of driving, because the required driving range for each individual user of the charging station is unknown. Therefore, the current infrastructure system presents a major problem: users either have to charge for a long time using a 100-volt or 200-volt household charging station, or drive to a charging station that charges quickly by stepping down from a 6,600-volt high-voltage line.

[0092] Therefore, for uses such as driving short distances within a nearby area to run errands and return quickly, even if the onboard battery has a low charge level, one would have to either go to the aforementioned charging station and spend a long time charging it unnecessarily, or use a home charging device that can only supply a low current, resulting in a long charging time that is disproportionate to the short time needed to complete the errand.

[0093] On the other hand, even if there is still charge remaining by the time one reaches a charging station, it is easy to imagine that people will often drive to a charging station quite far away in order to run errands in the nearby area, wait in line, charge more than necessary, and then return to the nearby area. Furthermore, it is quite possible that the time to complete the errands will have already passed during that time.

[0094] In light of these considerations, it is clear that the present invention is particularly excellent when an electric double-layer capacitor is used as a secondary battery for mobility devices used in urban areas. This is because rapid charging using an electric double-layer capacitor makes it possible to charge enough power to at least travel within a nearby area. In other words, by using an electric double-layer capacitor in a so-called empty state with a charge level close to zero as a secondary battery, it is possible to rapidly charge it by safely and quickly supplying a much larger current than that of a lithium-ion secondary battery, which is a chemical secondary battery.

[0095] Furthermore, the present invention is not limited to being particularly suitable for rapid charging of electric vehicles and subsequent driving in nearby areas, as described above. It can also demonstrate its advantages when a secondary battery consisting of an electric double-layer capacitor is installed in electric wheelchairs and the like, which are expected to need to be supplied to the market in large quantities in recent years due to the rapidly aging population.

[0096] Specifically, current electric wheelchairs use lithium-ion batteries as their power source. These current electric wheelchairs are designed to operate for, for example, 10 hours at a speed of 4 kilometers per hour. In other words, a wheelchair equipped with a lithium-ion battery typically travels 20 kilometers on a single charge of approximately 8 hours. However, these specifications deviate significantly from actual usage patterns, making them extremely inconvenient to use.

[0097] This is because charging would take nearly eight hours, and realistically, it's highly unlikely that someone would need to travel 20 kilometers in an electric wheelchair after a full charge.

[0098] In other words, if charging can be completed in one hour, then being able to travel 5 kilometers on an electric wheelchair is sufficient. Furthermore, if rapid charging allows for a sufficient charge to be completed in about 30 minutes, enabling travel within a 5-kilometer range, the usability of the electric wheelchair will be greatly improved. In short, using a physical secondary battery consisting of an electric double-layer capacitor is particularly suitable as a power source for such small, short-distance mobility devices used in urban areas.

[0099] Furthermore, lithium-ion batteries used as power sources for electric wheelchairs are charged over a considerable period of time using a constant, small current from a household AC 100-volt power supply, for example, and voltage is not considered. In other words, because they are chemical secondary batteries with limited charging capacity, they cannot be charged by charging devices capable of very high power output.

[0100] This is because a large current cannot be supplied to the lithium-ion battery during charging. In other words, if a large current is supplied during charging, it will generate heat based on the characteristics of a chemical secondary battery, which can damage the secondary battery itself or cause a fire.

[0101] As is clear from the above, charging lithium-ion batteries is limited to household power sources such as AC 100 volts or AC 200 volts, which means charging takes a long time and is inconvenient to use.

[0102] In other words, even when driving in a nearby area after charging, if a large current is applied for rapid charging, the chemical secondary battery may be damaged or become hot due to the heat reaction, which can accelerate the chemical reaction and eventually increase the risk of fire.

[0103] The reason for this is that, in the case of a chemical secondary battery involving chemical reactions, from an electrical perspective, these chemical reactions are equivalent to electrical resistance. In other words, a chemical secondary battery inherently involves charging and discharging while undergoing chemical reactions, which, from an electrical perspective, can be considered equivalent to resistance that makes it difficult for current to flow and converts electrical energy into heat.

[0104] This can be said to be the inherent nature of lithium-ion secondary batteries, which are chemical secondary batteries. In other words, lithium-ion batteries are based on the premise that lithium ions move between electrodes. Specifically, in chemical secondary batteries such as lithium-ion batteries, one electrode releases ions such as lithium as a result of a chemical reaction, and the other electrode adsorbs these ions, thereby generating an electric charge, or current. This is because they utilize a chemical reaction called an intercuration reaction, in which lithium ions enter between the upper and lower layers of the plate-like crystalline structure of graphite that makes up one of the electrode plates of a lithium-ion battery and remain within the electrode.

[0105] Because of this structure, each time a chemical secondary battery is charged and discharged, intercuration reactions occur, where particles enter and exit the gaps in the electrodes. With each chemical reaction, the gaps in the plate-like crystals of the electrodes widen and narrow, putting stress on them. This stress progresses, gradually destroying the plate-like crystals, which in turn causes the battery's capacity to gradually decrease and shortens its lifespan.

[0106] Furthermore, when rechargeable batteries, such as lithium-ion batteries, which involve chemical reactions, are charged and discharged, if the temperature rises by 10 degrees Celsius due to these chemical reactions, the reaction rate may double, for example. This can cause the rechargeable battery itself to overheat, leading to further reactions, which can eventually result in the battery being damaged or even cause a fire.

[0107] On the other hand, in the case of an electric double-layer capacitor as a physical battery, charging and discharging are performed by simply moving positive and negative ions in the electrolyte between the electrodes, and since no chemical reaction is involved, the chemical reaction seen in chemical batteries does not depend on temperature. In this respect, physical secondary batteries are fundamentally different from chemical secondary batteries.

[0108] As mentioned above, lithium-ion batteries are constructed in a way that chemical reactions cause ions to move between the positive and negative electrodes, and this configuration itself acts as an electrical resistance. On the other hand, in electric double-layer capacitors, the ions that are already present in the electrolyte simply move between the positive and negative electrodes, so no chemical reactions occur, and the electrical resistance is much lower than that of chemical secondary batteries.

[0109] In other words, the internal structure of a physical secondary battery, such as an electric double-layer capacitor, is completely different from that of a chemical secondary battery, such as a lithium-ion battery, which is the reason why the maximum amount of current that can be supplied differs.

[0110] Based on the unique physical configuration of secondary batteries, many electric double-layer capacitors are capable of handling currents of up to 2,000 amperes during rapid charging. Furthermore, regarding the internal structure of the capacitor, by implementing structural modifications to facilitate current flow, it becomes possible to supply virtually unlimited current. (a) For example, by increasing the thickness of the metal that makes up the electrodes. (b) Thicken the structural material that attracts electric charge to the electrodes. This will allow a larger current to flow.

[0111] As explained above, in the case of electric double-layer capacitors, there are practically no constraints on the current values ​​for charging and discharging. Therefore, the more current that is supplied during charging, the faster the charging becomes, and the more energy can be stored in a short time.

[0112] This concept can also be applied to charging other types of batteries. For example, in the case of electric vehicles (EVs) equipped with very large charging batteries, such as 40 kilowatts or 80 kilowatts, this concept can be applied when charging using a charging station that directly utilizes the 6,600-volt voltage supplied directly from high-voltage lines.

[0113] On the other hand, in home charging, the maximum amount that can be charged is about 1 kilowatt. This is because, with a 100-volt household power supply, it is not recommended to continuously supply more than 10 amperes of current from a single outlet.

[0114] In a home setting, it's impossible to supply extremely large amounts of power, such as a charging station that uses 6,600 volts directly from high-voltage lines. In other words, the challenge in a home is how to efficiently charge secondary batteries with the limited power available.

[0115] In the case of a 6,600-volt charging device that draws electricity directly from a high-voltage line, it outputs a constant large current even at a high voltage. However, if this extremely high voltage value is reduced and the current value is increased instead, the rapid charging power can be kept constant, and the output current can be increased or decreased according to the voltage value. If this is within the allowable range of the secondary battery, charging can be done in an even shorter time. However, this is extremely difficult to do with secondary batteries, which involve chemical reactions.

[0116] Furthermore, with current lithium-ion batteries, such as those used in electric wheelchairs, attempting to supply a current exceeding a certain value using a 6,600-volt high-voltage power supply will damage the battery itself because it is a chemically rechargeable battery. Therefore, the only option is to use a small-capacity household charger with a 100-volt or 200-volt household power supply. In other words, it is impossible to rapidly charge the battery just before an urgent task to ensure it is ready in time.

[0117] However, in the case of an electric wheelchair equipped with an electric double-layer capacitor as a secondary battery, since it involves charging a physical secondary battery, this secondary battery consisting of an electric double-layer capacitor can be rapidly charged by combining it with the constant power / current output power supply according to the present invention. On the other hand, if a chemical battery such as the lithium-ion battery currently widely used is forcibly rapidly charged, the chemical reaction will become an electrical resistance, which is highly likely to cause the aforementioned heat generation and the abnormal acceleration of unexpected chemical reactions. As a result, it is possible to prevent major accidents such as damage to the secondary battery or fire caused by combustion. In other words, it is understood that combining a secondary battery consisting of an electric double-layer capacitor with the constant power / current output power supply according to the present invention will enable its widespread adoption on a global scale in the future.

[0118] Furthermore, the following are other useful applications of combining the aforementioned electric double-layer capacitor as a secondary battery with the constant power / current output power supply according to the present invention. Specifically, if the electric double-layer capacitor is used as a secondary battery in meal delivery and serving robots that are expected to be widely used in the future in restaurants and hotel dining areas, care homes which are increasing due to the rapidly aging population, and hospitals equipped with inpatient wards, as well as in multilingual reception and guidance robots that are expected to be used at hotel front desks and public facilities, it will be possible to rapidly charge them in a limited time. In other words, it will be possible to improve the operating rate of these robots and respond to unexpected concentrations in robot operating hours, thereby contributing to the effective use of these robots.

[0119] As explained above, this invention focuses on electric double-layer capacitors as secondary batteries. However, as another embodiment of this invention, it can also be applied to so-called chemical secondary batteries, such as lithium-ion batteries, by changing the perspective from the viewpoint described above. While secondary batteries using sodium and potassium are also being developed and supplied to the market, in this invention, the term "lithium-ion battery" is used to refer to all of these chemical secondary batteries. In other words, it should be emphasized that the chemical secondary batteries to which this invention can be applied are not limited to the "lithium-ion batteries" described below, but also include secondary batteries using sodium and potassium.

[0120] For example, using a typical household power supply of 100 or 200 volts, it takes approximately 8 to 12 hours to charge a lithium-ion battery. However, when charging a lithium-ion secondary battery using the constant power / current output power supply according to the present invention, by constantly measuring the current value supplied from this constant power / current output power supply to the lithium-ion secondary battery to be charged, as well as constantly measuring the time for which the current is supplied, it becomes possible to accurately determine the amount of charge accumulating in the lithium-ion secondary battery from these measurement results.

[0121] Furthermore, by stopping charging with a sufficient margin (safety factor), such as limiting the charge to approximately 40% to 70% of the lithium-ion secondary battery's allowable charge capacity, it becomes possible to repeatedly charge the lithium-ion secondary battery, which is a chemical secondary battery, without causing a rapid chemical reaction that generates heat. For this reason, it should be added that, provided that charging is performed with such a margin, the present invention can also be applied to charging lithium-ion secondary batteries and the like.

[0122] This makes it possible to quickly charge an electric vehicle (EV) to the necessary and sufficient amount for driving in a nearby area, allowing the EV to be driven in time for shopping before closing time or for a scheduled hospital appointment. Similarly, in the case of the electric wheelchair mentioned above, by charging in a way that is not excessive and has ample margin so as not to cause heat generation due to chemical reactions in the lithium-ion secondary battery, it becomes possible to use the electric wheelchair within the area where it is driven in normal daily life.

[0123] Furthermore, as mentioned above, the constant power / current output power supply according to the present invention can be greatly utilized to rapidly charge existing lithium-ion secondary batteries with a sufficient margin in a short time for meal delivery and serving robots, which are expected to be widely used in the future in restaurants and hotel dining areas in urban areas, care homes which are increasing due to the rapidly aging population, and hospitals equipped with inpatient wards, as well as for multilingual reception and guidance robots that are expected to be used at hotel front desks and public facilities.

[0124] Finally, although this partially overlaps with the above, we will promote the widespread use of physical secondary batteries consisting of electric double-layer capacitors in various fields, and reaffirm the outstanding advantages of using these secondary batteries in combination with the constant power / current output power supply according to the present invention, unlike chemical secondary batteries such as lithium-ion batteries, which involve chemical reactions and have various limitations on rapid charging.

[0125] In the case of lithium-ion batteries, which are currently the mainstream in various fields, it is necessary to manufacture them with strict specifications for the positive electrode active material, negative electrode active material, and the electrolyte between them in order to maintain consistent characteristics as a secondary battery. This is because, in the finished battery, variations in capacity, or deviations, mean that battery units with low capacity will determine the overall storage capacity of the energy storage device. Therefore, in order to use them as high-capacity secondary batteries for electric vehicles (EVs), for example, the structure of lithium-ion secondary batteries must be manufactured with high precision and minimal deviation, and the manufacturing process and verification of manufacturing variations must be quite large-scale, resulting in high manufacturing costs.

[0126] On the other hand, in such chemical batteries, if the specifications of the positive electrode active material, negative electrode active material, and the electrolyte between them are not strictly controlled to reduce the internal resistance of the battery, when a secondary battery is fully charged in a short time, the internal temperature of the battery itself may rise due to heat generated by the internal resistance, or temperature increases may vary between batteries and even within the battery due to various variations in the manufacturing process. This can cause some batteries to break down due to the rapid temperature increase, leading to an accelerating increase in the rate of chemical reactions and the resulting self-heating, which can cause damage or fire.

[0127] On the other hand, electric double-layer capacitors do not involve the chemical reactions or lithium ion movement (which are considered equivalent to electrical resistance) seen in chemical batteries such as the lithium-ion batteries mentioned above. Instead, only the movement of electrolyte ions in the electrolyte solution and adsorption and desorption to and from the electrodes occur. This eliminates changes in materials and ion movement between electrodes, resulting in advantages such as low electrical resistance and short reaction times.

[0128] Specifically, it has the characteristics of exhibiting almost no performance degradation even after repeated charging and discharging, reaching a cycle life of several million cycles, and also having a significantly faster charging speed compared to chemical batteries.

[0129] Therefore, such secondary batteries have a strong potential to become widespread rapidly in the future. The advantages of electric double-layer capacitors are that they store energy by the movement of ions in the electrolyte between electrodes, resulting in low internal resistance, very little heat generation even when current flows, minimal degradation of characteristics because there is no degradation associated with charging and discharging since it is not a chemical reaction, and the ability to instantaneously supply current up to the maximum allowable current due to the physical structure of the capacitor.

[0130] Furthermore, I will discuss the special circumstances that stand in the way of producing lithium-ion rechargeable batteries cheaply and in large quantities. One of these special circumstances is that, in obtaining lithium as a raw material for lithium-ion batteries from producing countries that produce it in large quantities, there are currently various complex constraints stemming from complex factors such as diplomatic ties, economic relations, and the balance of power between nations. This is because, like nickel and cobalt, which are rare metals used as raw materials for other chemical rechargeable batteries, it is difficult to obtain lithium cheaply, easily, and in large quantities.

[0131] On the other hand, for our country, an maritime nation surrounded by the sea, if lithium could be efficiently extracted from seawater, it would be possible to obtain an inexhaustible supply of lithium from seawater without being subject to the aforementioned constraints. However, unfortunately, there is no prospect of realizing technology to efficiently recover lithium, which is present in extremely small amounts in seawater, in the near future.

[0132] On the other hand, although unrelated to the difficulties in obtaining lithium, addressing the rapid changes (deterioration) in the global environment in recent years has become an urgent global issue. Specifically, this is as follows:

[0133] In recent years, climate change caused by global warming has become a serious global problem, and the adoption of electric vehicles (EVs) is being promoted worldwide to address these issues. Furthermore, with the increasing popularity of EVs, there are urgent challenges in rapidly and widely deploying them, such as extending the driving range per charge, deploying EVs in larger vehicles to handle greater logistics, and expanding their use in public transportation like buses.

[0134] Furthermore, the conventional basic idea of ​​electricity supply has been to install large-scale power plants such as nuclear power plants, thermal power plants, hydroelectric power plants, and other wind and tidal power plants in locations somewhat far from urban areas, and to supply electricity to urban areas from these power plants using equally large-scale transmission systems.

[0135] On the other hand, the existing system, which can only stably supply electricity if all such large-scale infrastructure facilities are operating without problems, is now facing various issues. For example, Japan's entire territory and surrounding sea area are located on various tectonic plates, including the Eurasian Plate, the North American Plate, the Pacific Plate, and the Philippine Sea Plate, making it impossible to predict when a major earthquake, a large-scale volcanic eruption, a major earthquake, a tsunami accompanying a major earthquake, or a fire may occur. And once such a disaster occurs, there is a risk that the aforementioned power generation infrastructure facilities will malfunction, causing a sudden decrease or even complete loss of power supply capacity to urban areas.

[0136] This can be caused not only by such natural phenomena, but also by damage to infrastructure, particularly power transmission systems, due to river flooding resulting from the arrival of massive typhoons and linear rainbands caused by large-scale low-pressure systems associated with global warming.

[0137] Similarly, the same applies to man-made disasters caused by unpredictable and sudden conflicts between nations, terrorist acts against power infrastructure, and other such events.

[0138] Furthermore, it is essential to establish evacuation centers in various locations for disaster victims in the event of major disasters or those caused by extreme weather, as described above, and to also install rescue systems in these disaster relief facilities to protect those who become seriously ill or injured.

[0139] As is clear from the above explanation, it is important to widely popularize the large-capacity electric double-layer capacitor, which was described as part of the gist of the present invention, as a secondary battery. Furthermore, by using the charging device and charging method of an energy storage device using the electric double-layer capacitor according to the present invention together, it is possible to fully demonstrate the various advantages of the large-capacity electric double-layer capacitor as a physical secondary battery, which differ from chemical secondary batteries.

[0140] It should be noted that the circuit block diagrams and voltage / current (power) characteristic diagrams shown in the above-described embodiments and their modifications are merely examples, and it goes without saying that the structure, materials, circuit configuration, etc., can be appropriately modified within the scope that allows the effects of the present invention to be realized. [Explanation of symbols]

[0141] 10. First constant power / current output power supply 20. Second constant power / current output power supply 30. Third constant power / current output power supply 50 AC power supply 70. Secondary battery (electric double-layer capacitor) 100(100-1,100-2,…100-N) Constant current source 110 Primary side of the transformer 111 Amplifier 112 Control Function Unit 115 High-speed switching elements 120 Transformer secondary side 121 Current Value Detection Unit 122 Rectifier Diode 124 Voltage Value Comparison Section 125 Error detection unit 126 Insulated separation section 127 Full-wave rectification, smoothing function, and step-up / step-down circuit 130 Current Value Determination / Switch Switching Control Unit 131 Voltage Value Detection Unit 132 Current Value Determination / Switching Update Unit 133 Switch control signal transmission unit 140 Full-wave rectification / smoothing circuit 150 Constant Current Source Operation Changeover Switch Group 210 Primary side of the transformer 211 Amplifier 212 Control Function Unit 220 Transformer secondary side 221 Voltage / Current Value Detection Unit 224 Power Value Calculation Unit 225 Error calculation section 226 Insulated Separation Section 227 Full-wave rectification, smoothing, and current value control function section 240 Full-wave rectification / smoothing circuit 250 (Tp1, Tp2, ... TpN) Tap (Switching terminal) 260 (TSW1, TSW2, ... TSWN) Tap changeover switch 350 MOSFETs (FSW1, FSW2, ... FSWN)

Claims

[Claim 1] A constant power supply method that enables the supply of a constant power for charging an energy storage element consisting of an electric double-layer capacitor, The charging voltage applied to the energy storage element is detected, Based on both the predetermined power supplied to the energy storage element and the charging voltage, the current value to be supplied to the energy storage element at that time is determined. Based on the determined current value, the number of constant current sources that supply a constant power to the energy storage element is changed in stages from among a plurality of constant current sources, thereby ensuring that a constant power is always supplied to the energy storage element while it is being charged, A method for supplying constant power to an energy storage element, characterized in that, regarding the stepwise change in the current value flowed from a constant current source to the energy storage element during charging, in a correlation characteristic diagram of output voltage and required current value with the value flowed to the energy storage element during charging on the horizontal axis and the voltage applied to the energy storage element on the vertical axis, the output current value corresponding to the required current value shown on the horizontal axis decreases in a stepwise manner as the output voltage value shown on the vertical axis of the correlation characteristic diagram increases in a stepwise manner.

Images