WO2015112005A1 - Method for controlling transfer of electric energy into and out at least one rechargeable energy storage device - Google Patents

Method for controlling transfer of electric energy into and out at least one rechargeable energy storage device Download PDF

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Publication number
WO2015112005A1
WO2015112005A1 PCT/NL2015/050029 NL2015050029W WO2015112005A1 WO 2015112005 A1 WO2015112005 A1 WO 2015112005A1 NL 2015050029 W NL2015050029 W NL 2015050029W WO 2015112005 A1 WO2015112005 A1 WO 2015112005A1
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WO
WIPO (PCT)
Prior art keywords
predetermined
battery
charge
value
state
Prior art date
Application number
PCT/NL2015/050029
Other languages
French (fr)
Inventor
Tjerk Egbert Bernard GOOSSEN
Original Assignee
N.V. Nederlandsche Apparatenfabriek "Nedap"
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Publication of WO2015112005A1 publication Critical patent/WO2015112005A1/en

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0063—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with circuits adapted for supplying loads from the battery
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/007—Regulation of charging or discharging current or voltage
    • H02J7/00712—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/0029—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries with safety or protection devices or circuits
    • H02J7/00306—Overdischarge protection

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Charge And Discharge Circuits For Batteries Or The Like (AREA)
  • Secondary Cells (AREA)

Abstract

Method for controlling transfer of electric energy in to and out at least one rechargeable battery comprising setting a minimum value representing an allowed minimum State of Charge (SoC) of the battery wherein a discharging of the battery is stopped if a value representing the State of Charge of the battery reaches the minimum value representing the minimum State of Charge of the battery, wherein the method comprises varying the minimum value (60) as a function of a value representing the State of Charge of the battery wherein the function is such that the minimum value (60) is decreased if within a predetermined period the value representing the State of Charge exceeds a first predetermined minimum requirement (62) and the minimum value is increased if during a predetermined period the value representing the State of Charge does not exceed a second predetermined minimum requirement (64) wherein the second predetermined minimum requirement corresponds with a lower State of Charge of the battery then the first predetermined minimum requirement.

Description

Title: Method for controlling transfer of electric energy into and out at least one rechargeable energy storage device.
The invention relates to a method for controlling a transfer of electric energy in to and out at least one rechargeable battery, comprising setting a minimum value representing an allowed minimum State of Charge (SoC) of the battery wherein a discharging of the battery is stopped if a value representing the State of Charge of the battery reaches the minimum value representing the minimum State of Charge of the battery.
Furthermore the invention relates to a battery charging and discharging unit arranged to be connected to a battery for controlling a transfer of electric energy in to and out at least one rechargeable battery wherein the battery charging and discharging unit is arranged for setting a minimum value representing an allowed minimum State of Charge (SoC) of the battery wherein a discharging of the battery is stopped by the battery charging and discharging unit if a value representing the State of Charge of the battery reaches the minimum value representing the minimum State of Charge of the battery.
Such a method and battery are known.
Generated electric energy such as solar power and wind power can be used to support an energy consuming load. However, generally, power generation and power consumption do not exactly coinside. A battery may be used to store a surplus of generated power and to provide additional power to support the load if the generated power is not sufficient. The State of Charge (SoC) (i.e. the amount of energy left in the battery) may have a significant impact on the lifetime of the battery. For example, if a battery such as a lead-asset battery is kept at a low SoC, then the lifetime of the battery can be shortened significantly. In these cases long periods with a low SoC should be avoided.
Therefore it is known to specify a minimum required energy level for the battery. This means that, if this level is reached, no more energy will be drawn from the battery and lower energy levels of the battery are thus prevented. As soon as the minimum energy level in the battery is reached, the loads could, for example, switch over to other power sources such as a public grid. The use of a minimum required energy level for the battery improves the lifetime of the battery. However a minimum required energy level hmits the amount of energy that can be used for desired functionality of the system. It is an object of the invention to extend the battery lifetime with minimum impact on functionality.
The method according to the invention is characterized in that the method comprises varying the minimum value representing the allowed
State of Charge of the battery as a function of a value representing the State of Charge of the battery wherein the function is such that the minimum value is decreased at least if within a predetermined period the value representing the State of Charge exceeds a first predetermined minimum requirement and the minimum value is increased at least if during a predetermined period the value representing the State of Charge does not exceed a second predetermined minimum requirement wherein the second predetermined minimum requirement corresponds with a lower State of Charge of the battery than the first predetermined minimum requirement. Because in accordance with the invention the minimum State of Charge may be increased if circumstances permit, the average SoC of the battery during its use may be higher than the situation wherein a fixed minimum SoC is used. This can be beneficial for the lifetime of the energy storage device. It is noted that the minimum value is increased at least if within a predetermined period the value representing the State of Charge exceeds the first predetermined minimum requirement. This means that this is at least one of the requirements which must be met for the increase of the minimum value. In some embodiment this can be the only requirement which has to be met. It may however be that other requirements also have to be met for increasing the minimum value, such as for example the requirement that the minimum value of the value representing the State of Charge reached is within a predetermined time period within a
predetermined distance to the actual minimum value. It is also noted that the minimum value is decreased at least if within a predetermined period the value representing the State of Charge does not exceeds the second predetermined minimum requirement. This means that this is at least one of the requirements which must be met for the increase of the minimum value. In some embodiments this can be the only requirement which has to be met for this increase. It may however be that other requirements also have to be met, such as the requirement that the minimum value of the value representing the State of Charge reached is within a predetermined time period outside a predetermined distance to the actual minimum value.
According to a special embodiment it holds that the method comprises at least the following steps:
- a step a. wherein the minimum value is decreased;
- a step b. wherein the minimum value is increased; wherein
step a. is carried out if within at least a first predetermined period of time a value representing the State of Charge of the battery is at least for one moment in time larger than a first predetermined value; and wherein step b. is carried out if within at least a second predetermined period of time the value representing the State of Charge of the battery is sat least during a predetermined length of time smaller than a second predetermined value wherein preferably the first predetermined period of time is the second predetermined period of time.
A period of time may for example be an hour or a day. Other time durations are also possible. Step b. increases the average State of Charge of the battery wherein step a. may avoid a strict limitation to a high State of Charge of the battery so that for example a surplus of energy can still be loaded in the battery. In accordance with a preferred embodiment the controlling of the transfer of electric energy takes place in subsequent predetermined periods in time, wherein step a. is carried out if within any predetermined period of a predetermined collection of the predetermined periods a value representing the State of Charge of the battery is larger than the first predetermined value and optionally also if within any predetermined period of a predetermined collection of the predetermined periods a value representing the State of Charge of the battery is equal to the first predetermined value, wherein step a. comprises decreasing the minimum value in a next period. The predetermined range can be selected such that for the specific type of battery which is used, its lifetime can be extended to an optimum. It may further hold that step b. is carried out if within any predetermined period of a predetermined collection of the predetermined periods the value representing the State of Charge of the battery is at least during predetermined length of time smaller than the second predetermined value and optionally also if within any predetermined period of the predetermined collection of the predetermined periods a value representing the State of Charge of the battery is at least during a predetermined length of time equal to or smaller than the second
predetermined value, wherein step b. comprises increasing the minimum value in a next predetermined period. In each case the predetermined collection of the predetermined periods may for example comprise only the latest most recent predetermined period, only the i most recent
predetermined periods wherein i= 2, 3, 4..n or any other predetermined collection of predetermined periods..
The battery charging and discharging unit according to the invention is characterized in that the battery charging and discharging unit is further arranged for, varying the minimum value representing the minimum allowed State of Charge of the battery as a function of a value representing the (actual) State of Charge of the battery, wherein the function is such that the minimum value is decreased if within a
predetermined period the value representing the State of Charge exceeds a first predetermined minimum requirement and the minimum value is increased if during a predetermined period the value representing the State of Charge does not exceed a second predetermined minimum requirement wherein the second predetermined minimum requirement corresponds with a lower State of Charge of the battery than the first predetermined minimum requirement.
The system according to the invention comprises a battery, a power generating unit connector which can be connected with a power generating unit, a battery charging and discharging unit as discussed above, and a load connector which can be connected with a load, wherein the power generating unit connector, the battery charging and discharging unit and the load connector are connected to each other for the transfer of electric energy between the power generating unit connector, the battery charging and discharging unit and the load connector and wherein the battery is connected to the battery charging and discharging unit for charging and discharging the battery wherein the system is adapted to submit electric energy from the power generating unit connector to the load connector and/or the battery charging and discharging unit for charging the battery and wherein the system is adapted to submit electric energy from the battery via the charging and discharging unit to the at least one load connector, wherein the battery charging and discharging unit is arranged for carrying out the method as discussed above.
Preferably it holds that the system is further provided with a power grid connector which is connected with the power generating unit connector, the battery charging and discharging unit and the load connector for submitting energy from the power grid connector to the load connector and/or for submitting energy from the power generating unit connector and/or the battery charging and discharging unit to the power grid
connector. Because the system is provided with a power grid connector, electric energy can be drawn from the power grid for supplying electric energy to the load in case the battery has reached a State of Charge which is equal to the allowed minimum State of Charge so that it is no longer possible to supply electric energy from the battery to the load.
It is noted that in this application a battery is a means comprising chemical substances for storing and releasing electrical energy.
The variation includes galvanic cells, electrolytic cells, fuel cells, flow cells and voltaic piles. A battery is for example: a lead-acid battery such as a car battery, a sealed valve regulated lead-acid battery (VELA battery) such as Gel batteries (or "gel cell") and Absorbed Glass Mat (AGM) batteries and a "dry cell" battery such as nickel-cadmium (NiCd), nickel-zinc (NiZn), nickel metal hydride (NiMH) and lithium-ion (Li-ion) batterries.
Further objects, features, effects, advantages and details of the invention are described with reference to examples shown in the drawings.
In the drawings:
Figure 1 is a schematic diagram illustrating a system for an electrical installation of a building comprises a charging and discharging unit in accordance with the invention for carrying out a method according to the invention;
Figure 2 is a diagram showing a method wherein energy levels of a battery are regulated in accordance with a prior art system;
Figure 3 shows a method wherein energy levels of a battery are regulated in accordance with a first embodiment according to the present invention;
Figure 4 shows a method wherein energy levels of a battery are regulated in accordance with a second embodiment according to the present invention;
Figure 5 shows a method wherein energy levels of a battery are regulated in accordance with a third embodiment according to he present invention; and Figure 6 shows a method wherein energy levels of a battery are regulated in accordance with a fourth embodiment according to the present invention
FIG. 1 illustrates a simplified block diagram of a power control system 1 including at least one power generation unit, such as a solar panel 2 and a windmill 3. Although a windmill and a solar panel, i.e. a
photovoltaic system, are described as an example the invention is not limited to power generation units generating energy by solar power or by wind energy, but such a unit can generate power equally well from biogas, geothermal energy or other renewable resources.
A rechargeable battery 4 is present for storing electric energy and for providing electric energy. As discussed in accordance with the invention a battery is a general name for an energy storage unit such as a li-on battery, a supercap, and a battery such as used in cars and other electric energy storage means provided with electrochemical substances for storing and releasing electric energy.
At least one electrical load 5 of an electrical installation of a building is connected via an electrical load connector 6 to a junction 7. Such an electrical load 5 may be formed by any or all electrical appliances which can be present in a household or a commercial building.
An AC power grid or utility grid 8 (not belonging to the power control system 1) is connected to a power grid connection unit 9 by a line 10. In this way energy can be drawn from or fed into the power grid 8. A main or electric consumption meter 11 is connected to the power grid connection unit 9 by a line 12 and measures the amount of energy drawn from and fed into the power grid 8. The main meter may be arranged for measuring the amount of energy drawn from the power grid and for measuring the amount of energy fed into the power grid. However in this example the main meter is arranged for measuring the amount of energy drawn from the power grid minus the amount of energy fed into the power grid, thus a net amount of energy is measured which is supplied to the power grid or drawn form the power grid. Electrical energy from the power grid 8 is supplied to the at least one electrical load 5 via the grid connection unit 9, the main meter 11 and the junction 7 and passes through an electrical conductor 13.
A current sensor 14 is positioned along electrical conductor 13 between junction 7 and the main meter 11 and is electromagnetically coupled to electrical conductor 13 without direct electrical connection to the electrical conductor 13. The current sensor 14 can, in one example, be a differential noncontact current sensor, such as a Rogowski coil having an open interior or AC Current transformers TT 100-SD or TT 50-SD from
LEM. In the presently most preferred embodiment the current sensor 14 is a clip-on current sensor using magnetic inductivity to measure the direction of the AC current (and optionally the value of the current) flowing within the electrical conductor 13. Such clip-on sensors are known per se. Using this type of non-contact current sensor provides several advantages. It makes retrofit operation simple because the original wiring need not be interrupted or changed; the current sensor can be simply clipped on the electrical conductor without disturbing the conductor. Other types of non- contact current sensors, such as other differential sensors or proportional sensors, including magnetic field current sensors, current transformers, and Hall effect sensors, can also be used in different embodiments of the invention. The current sensor 14 creates a current sensor signal
representative of at least the direction of the current flowing through the electrical conductor 13 and, optionally after calibration, a signal
representative of the value of the amount of current flowing through the electrical conductor 13.
The power control system 1 also includes a power management unit 15 comprising a microprocessor or any other suitable control means 16 which is connected to the current sensor 14 by a current sensor signal line 17, which signal line 17 transports the current sensor signal from the current sensor 14 to the control means 16. In this example the power management unit 15 further comprises a bus 18 and a plurality of modules 19, 20, 21, 22 which are detachably connected with the bus 18 for mutually exchanging electrical energy between the modules via the bus 18.
Each module 21; 22 has a bus connector 23; 24 which is, as shown in this example, operatively electrically connected with the bus 18 for supplying energy to the bus 18. Each module 21; 22 is further provided with a power generation unit connector 25; 26 which is operatively connected with the solar panel 2 and the windmill 3, for drawing energy from the respective power generation unit via the connectors 50, 52.
The module 20 of the power management unit 15 is a battery charging and discharging unit 20 provided with a bus connection 27 which is, as shown in this example, operatively electrically connected with the bus 18 and a battery connector 28 which is operatively electrically connected with the battery 4 for, as desired, supplying energy to the bus via the bus connector 27 and drawing energy from the energy storage unit 4 via the battery connector 28 or drawing energy from the bus via the bus connector 27 and supplying energy to the battery 4 via the battery connector 28.
The module 19 of the power management unit 15 is provided with a bus connector 29 which is, as shown in this example, operatively electrically connected with the bus 18 and a connector 30 which is operatively electrically connected with the junction 7 via a power meter 31 for, as desired, drawing energy from the bus 18 via the bus connector 29 and supplying energy to the at least one electrical load 5 via the connector 30, the power meter 31 and the junction 7 and/or drawing energy from the power grid 8 and supplying energy to the at least one electrical load 5 via the power grid connection unit 9, the main meter 11 and the junction 7. Thus in this example the connector 30 functions both as a load connector and a power grid connector. The power meter 31 measures the amount of energy which is supplied from unit 19 towards the junction 7. In this example the voltage on the bus is a DC voltage wherein the module 19 transforms a DC current from the bus into an AC current through the power meter 31 and vice versa. The current supplied to the connections 25, 26, 28 is however in this example a DC current. In each of the examples discussed the power meter is optional and may be deleted. In that case in the example the unit 14 is directly connected to the junction 7. Also in that case in the example the power management unit 15 is directly connected to the junction 7. The power meter 31 is in that case in the example replaced by a direct connection via a wire.
In this example, the control means 16 generates control signals on a line 32 connecting the control means 16 with each of the modules 19, 20, 21, 22 for respective control, such as activation or deactivation, of the modules. In case of the charging and discharging unit the control means may control the charging and discharging unit 20 to charge the battery with energy drawn from the bus 18 or to supply energy from the battery to the bus 18 as will be discussed, The charging and discharging unit itself may set a minimum value representing a minimum allowed State of Charge of the battery 4 as will also be discussed. In this example each module 19; 20; 21; 22 is further provided with a local control unit 33; 34; 35; 36 which is connected to the control means 16.
The power management unit 15 is adapted for controlling the energy flow between the at least one power generation unit 2, 3, the battery 4, the at least one electrical load 5 and the power grid connection unit 9 with the help of the control means 16, the local control units 33, 34, 35, 36 and at least based on the current sensor signal created by the current sensor 14.
The power management unit 15 controls the energy flows based on the current sensor signal such as to try to regulate the electrical current through the electrical conductor 13 to zero. Thus the power management unit 15 tries to control the energy flows such that the electrical current drawn from the power grid is low as possible, preferably zero. In case internal energy (i.e. energy provided by the combination of the at least one power generation unit 2, 3 and the battery is sufficient to cover the electrical demands of the at least one electrical load 5, the power management unit 15 is able to control the energy flows such that the current through the electrical conductor 13 is exactly zero. Preferably, the power management unit 15 controls the energy flows such that first the energy supplied by the power generation units 2, 3 is used to cover the demands of the at least one electrical load 5. If the power generation units 2, 3 produce more energy than the energy drawn by the at least one load 5, the surplus energy is supplied to or stored in the battery 4 via the battery charging and discharging unit 20. Only in case the battery 4 is fully loaded and/or the required charging capacity of the battery is too small (so that the battery can not be loaded with the full surplus of energy flow), then the power management unit 15 feeds the portion of the surplus of energy flow which can not be loaded into the battery 4 into the power grid. Than said current is not zero although it is tried by the power management unit to regulate said current to zero. If the power generation units 2, 3 produce not enough energy with respect to the energy drawn by the at least one load 5, the control of the power management unit 15 is such that the remaining energy is drawn from the battery 4 via the battery charging and discharging unit 20 (than said current is not zero although it is tried by the power management unit to regulate said current to zero).
Thus only if the at least one power generation unit 2, 3 in combination with the battery4 are unable to meet the demand of the at least one electrical load 5, the power management unit 15 is unable to regulate the electrical current through the electrical conductor 13 to exactly zero, but then regulates this electrical current such that it is as close as possible to zero. The power management unit 15 then resorts to the power grid 8 for drawing the remaining energy. Alternatively the electrical load connector 6, and the current sensor 14 may be deleted. In that case the system 1 is further provided with a module 40 which is provided with a bus connector 42 by means of which the unit 40 is electrically connected with the bus 18. Furthermore the module 40 is provided with a load connector 44 to which the load 5 is connected. The module 40 is further provided with a local control unit 46 which is connected with line 32 for receiving control signals from the control means 16. These control signals may for example allow the load 5 to draw energy from the bus 18. In such a system it is not tried to regulate the current through the current sensor 14 towards zero. The control means 16 in that case may for example via line 32 obtain information from the modules 21 and 22 how much power can be provided. At the same time it receives information from module 40 how much energy is required by the load 5. Based on this information the control means 16 may decide that if the power generation units 2,3 can provide more energy then required by the load 5, the surplus of energy will be stored via the charging and discharging unit 20 in the battery 4. Alternatively, if it appears that the load 5 requires more energy then can be supplied by the power generation units 2, 3 then the control means 16 may control the system such that a shortage of energy is drawn by the charging and discharging unit 20 from the battery 4.
It is known that the charging and discharging unit 20 may be arranged such that the State of Charge (SoC) (i.e. amount of energy left in the battery as a percentage of the total available capacity for energy storage of the battery) may be regulated to remain within certain limits. The State of Charge may have a significant impact on the lifetime of a battery. For example, if a Lead-acidbattery is kept at a low SoC, the lifetime can be shortened significantly. In these cases long periods with a low SoC should be avoided. Therefore a minimum required energy level for the battery can be specified so that, if this level is reached, no more energy will be drawn from the battery and lower energy levels within the battery are prevented. The charging and discharging units may be arranged to accomplish this. As soon as the minimum energy level of the SoC of the battery is reached, the energy could be drawn from the grid. However if the charging and discharging unit 20 indicates on line 32 that a minimum State of Charge of the battery 4 is reached, so that the battery can not be further unloaded without a risk of shortening the lifetime of the battery, then the control means 16 may control via line 32 the module 19 such that shortage of energy is obtained from the grid 8. In that case the charging and discharging unit may itself regulate that the battery 4 is no longer discharged. The energy is then submitted from the grid 8 via the module 19 to the bus 18. This energy which is supplied to the bus 18 is in combination with the energy supplied by the power generation units 2, 3 via the modules 21, 22, to the bus 18 supplied to the load 5 via the module 40. It may however also be regulated by the control means 16 that the battery can not be discharged because a value representing a minimum allowed State of Charge of the battery has been reached.
The energy levels of the battery can be represented using absolute units (for example joules, watt, power, ampere-hour) or can be expressed relative to the total storage capacity of the battery. In this example the SoC representation is used, but the results are comparable for all
representations. So in more general terms it can be said that there is a value representing a SoC. This value may be the SoC itself or one of the absolute units as discussed above.
As discussed it is known that a battery charge and discharge unit 20 can be arranged for setting a minimum value representing an allowed minimum State of Charge (SoC) of the battery. The battery charging and discharging unit is arranged such that this charging of the battery is stopped if the State of Charge of the battery reaches the minimum State of Charge. This is illustrated in figure 2.
In figure 2 the variation in time of energy levels of the battery 4 are shown. The timeline is provided with moments in time ti (i=l, 2, 3,... etc) wherein the lapse of time between two subsequent moments in time forms a time period. A period may for example be 24 hours, 12 hours, 6 hours, etc. Other time periods are also possible. The value representing the SoC is in this example the SoC itself. Thus if SoC is 100% this means that the battery is fully loaded. If SoC is 0%, this means that the battery 4 is completely empty. In figure 2 it is shown that at tl the value representing the State of Charge of the battery is raised up until 100%. This means, for example, that power generation units 2, 3 generated more energy then is used by the load 5. The generated energy which is not used by the load, is supplied into the battery which is than completely charged. If, after that the battery is fully charged there would still be a remainder of energy, then this energy can be supplied to the grid 8 as discussed above.
As can be seen in figure 2, during a next period following on tl, for possible reasons as discussed above, the battery is discharged until it reaches a SoC of 75%. This may for example, happen during the night when energy is used on the one hand by the load and energy is not generated on the other hand by the power generation units 2, 3. Then, during a next period, first energy is drawn from the battery and then the battery is charged again until the SoC of the battery reaches a value of about 90%. This may, for example, happen during the day when first less energy is generated than supplied to the load and later more energy is generated than supplied to the load. This results in a valley for the SoC. Than the SoC lowers again, for example because it becomes night. As can be seen in figure 2 during the next periods, the SoC is varying between peeks and valleys. It can also be seen in figure 2 that the battery charging and discharging unit avoids that the SoC decreases below a minimum value of the SoC of 30%. If the battery is discharged so that the minimum value of the SoC is reached discharging of the battery is stopped. If discharging of the battery is stopped, then in the example of figure 1 the required energy can be drawn from the grid 8. As can be seen from figure 2 there are many periods of time wherein the minimum State of Charge of the battery is reached. This is caused by the fact that a surplus of energy which is generated by the power generating means which is charged in the battery is subsequently fully consumed by the load so that the minimum State of Charge is reached again. Only during the periods between tl6 and t20, between t31and t36 and between t42 and t45 on average more energy is generated by the power generation units than subsequently consumed by the load so that if the battery is discharged, the minimum State of Charge is not reached. Thus it shows that in figure 2 a minimum value representing an allowed minimum State of Charge is 30%.
Based on figure 3 an embodiment of a system and a battery charging and discharging unit in accordance with the invention will be discussed. This battery charging and discharging unit 20 can be part of the system according to figure 1. The battery charging and discharging unit 20 according to this first embodiment of the invention is further arranged for carrying out the following steps:
- a step a. wherein the minimum value representing an allowed minimum State of Charge (SoC) of the battery is decreased;
- a step b. wherein the minimum value representing an allowed minimum State of Charge (SoC) of the battery is increased; wherein the battery charging and discharging unit (or the system) is arranged such that step a. is carried out if within at least a first predetermined period of time a value representing the State of Charge of the battery is at least for one moment in time larger than a first predetermined value; and wherein the battery charging and discharging unit (or the system) is arranged such that step b. is carried out if within at least a second predetermined period of time the value representing the State of Charge of the battery is at least during a predetermined length of time smaller than a second predetermined value wherein preferably the first predetermined period of time is the second predetermined period of time.
In figure 3 the minimum value is indicated by dotted line 60. The first predetermined value is indicated by dotted line 62. The second predetermined value is indicated by dotted line 64. The value representing the actual State of Charge of the battery is indicated by line 66. The periods of figure 3 are the same as discussed in relation with figure 2.
As can be seen from figure 3, the battery charging and discharging unit works as follows. If, such as for example is the case during period t6-t7, the value 66 representing the State of Charge of the battery is at least during a predetermined length of time smaller than the second predetermined value 64, then step b. is carried out. This means that the minimum value 60 is increased. Thus in this case the actual State of Charge during period t6-t7 comprises a local peak 68. This is caused on the one hand by, for example, supplying energy to the battery if more energy is generated than consumed by the load wherein subsequently the load consumes more energy than generated by the power generating means so that the State of Charge of the battery is lowered. It shows however that within period t6-t7 the actual value representing the State of Charge of the battery is always smaller than the second predetermined value 64. Therefore the minimum value is increased in the next period which lies between t7 and t8. As a result in that next period the discharging of the energy can only take place up until the new increased minimum value which is indicated in figure 3 with reference number 70 is reached. The previous minimum value is indicated with reference number 67. During the period between t7 and t8 it again holds that the value representing the State of Charge of the battery is always smaller than the second predetermined value 64 so that for the next period between t8 and t9the minimum value is increased again by the charging and discharging unit 19. If a minimum value is increased in this
embodiment, the increase is always with a step which amplitude is fixed. Thus if the minimum value is increased it is always increased with a predetermined increase value, in this case an increase value which corresponds with about 5% of energy level wherein the battery is fully loaded.
As is also shown in figure 3, between t30 and t31, the value representing the State of Charge of the battery is it least for one moment in time larger than the first predetermined value 62. This has as a result that for a next period, in this case the period between t31 and t31 the minimum value is decreased. Thus it holds in the example of figure 3 that if within at least a predetermined period of time the value representing the State of Charge of the battery 4 is at least for one moment in time larger than the first predetermined value 62 then step a. is carried out. According to a special embodiment it holds that if within at least a predetermined period of time the value representing the State of Charge of the battery 4 is at least for a predetermined length of larger than the first predetermined value 62 then step a. is carried out. The predetermined length of time can for example be 30% of the length of a period of time. According to an alternative special embodiment it may hold that if within at least a predetermined period of time the value representing the State of Charge of the battery 4 is at any moment in time larger than the first predetermined value 62 then step a. is carried out.
If a minimum value is decreased it is in these examples always decreased with a fixed decrease value which again corresponds with about 5% of the total amount of energy which can be loaded into the battery. It is also shown that for example, between tl3 and tl4 the value representing the State of Charge of the battery is not always smaller than the second predetermined value 64 and is not at any time larger than the first predetermined value 62. The charging and discharging unit (or the system 1) is arranged such that, as a result, the minimum value 60 remains unchanged. By comparing figure 2 and figure 3 it can be seen that the average value of representing the State of Charge of the battery is higher in figure 3. This can be beneficial for the lifetime of the battery.
It follows from the above that step b. is carried out if within any of the time periods the value representing the states of charge of the battery is always smaller that the second predetermined value 64, then step b is carried out . This is however merely an example. It is also possible, according to another embodiment that step b. is carried out if within at least a predetermined period the value representing the State of Charge of the battery is at least during a predetermined length of time smaller than the second predetermined value. The predetermined length of time can, for example, be 30% of the length of a predetermined period of time. As discussed the length of a predetermined length of time is equal to (ti+ 1)- ti.
In the embodiment of figure 3 it moreover holds that if within at least a predetermined period of time the value representing the State of Charge of the battery 4 is at least for one moment in time larger than or equal to the first predetermined value 62 then step a. is also carried out. Moreover it holds that if within at least a predetermined period of time the value representing the State of Charge of the battery is always or at least during a predetermined length of time smaller than or equal to the second predetermined value 64, then step b. is also carried out.
In this example it holds that deciding whether or not a step a. has to be carried out is based on the value representing the State of Charge of the battery in a previous period. The same applies mutatis mutandis for step b. Therefore it holds that the controlling of the transfer of electric energy takes place in the subsequent predetermined periods of time, wherein step a. is carried out if within any predetermined period of a predetermined collection of the predetermined periods a value representing the State of Charge of the battery is larger than the first predetermined value and optionally also if within any predetermined period of a
predetermined collection of the predetermined periods a value representing the State of Charge of the battery is equal to the first predetermined value, wherein step a. comprises decreasing the minimum value in a next period following the period wherein a value representing the State of Charge of the battery is larger than the first predetermined value or optionally following the period wherein a value representing the State of Charge of the battery is equal to the first predetermined value . The subsequent predetermined periods of time are the periods between ti and ti+1 for i=l,2,3,...etc. In this example the collection of the predetermined periods used for deciding whether or not step a. should be carried out comprises only the latest (previous) period. Other collections our however also possible such as the latest two periods etc.
Thus similarly it holds for step b. that step b. is carried out that if within any predetermined period of a predetermined collection of the predetermined periods the value representing the State of Charge of the battery 4 is at least during predetermined length of time smaller than the second predetermined value and optionally also if within any predetermined period of a predetermined collection of the periods a value representing the State of Charge of the battery is at least during a predetermined length of time equal to or smaller than the second predetermined value, wherein step b. comprises increasing the minimum value in a next period following the period wherein the value representing the State of Charge of the battery is at least during a predetermined length of time smaller than the second predetermined value or optionally following the period wherein a value representing the State of Charge of the battery is at least during a predetermined length of time equal to or smaller than the second
predetermined value. In this example the collection of the predetermined periods used for deciding whether or not step b. should be carried out comprises only the latest (previous) period. Other collections are however also possible such as the latest two periods etc.
In this case the mentioned predetermined lengths of time correspond with the length of a period of time. This means that it holds that step b. is carried out if within any predetermined period of the predetermined collection of the predetermined periods the value representing the State of Charge of the battery is always smaller than the second predetermined value and optionally also if within any predetermined period of the predetermined collection of the periods a value representing the State of Charge of the battery is always equal to or smaller than the second predetermined value. It further holds that step a. is carried out if during any moment in time within any predetermined period of the predetermined collection of the predetermined periods a value representing the State of Charge of the battery is larger than the first predetermined value and optionally also if during any moment in time within any predetermined period of the predetermined collection of the predetermined periods a value representing the State of Charge of the battery is equal to the first predetermined value. This is merely a possible embodiment because according to an alternative embodiment it is also possible that a step a. is carried out if during at least a predetermined length of time within any predetermined period of the predetermined collection of the predetermined periods a value representing the State of Charge of the battery is larger than the first predetermined value and optionally also if during at least the predetermined length of time within any predetermined period of a predetermined collection of the predetermined periods a value representing the State of Charge of the battery is equal to the first predetermined value. The predetermined length of time can for example be 20% of the length of a predetermined period of time.
Based on figure 3 it will also be clear that the battery charging and discharging unit is arranged such that, the value representing the minimum State of Charge of battery is changed such that local peaks P in the variations in time of the value representing the State of Charge of the battery lay between the first predetermined 62 value and the second predetermined 64. The local peaks are indicated with the character P is figure 3.
On a more general level it thus holds in accordance with the invention that the battery charging unit is arranged for varying the minimum value representing the minimum allowed State of Charge (SoC) of the battery 4 as a function of a value representing the State of Charge of the battery 4, wherein the function is such that the minimum value is decreased if within a predetermined period the value representing the State of Charge exceeds a first predetermined minimum requirement and the minimum value is increased if during a predetermined period the value representing the State of Charge does not exceed a second predetermined minimum requirement wherein the second predetermined minimum requirement corresponds with a lower State of Charge of the battery than the first predetermined minimum requirement. The requirement "if within a predetermined period the value representing a State of Charge exceeds a further predetermined minimum requirement" is embodied the example of figure 3 for example by the requirement that within any of the periods the value representing the State of Charge exceeds (for example for a
predetermined length of time or for a moment in time) the first
predetermined value 62. Also the requirement "if during a predetermined period the value representing the State of Charge does not exceed a second predetermined minimum requirement" is embodied in the examples of figure 3 for example by the test whether the value representing the State of Charge does not exceed the second predetermined value 64 (always or during at least a minimum length of time) during any of the periods of time. The invention is not limited to the above referred to special embodiment. It is for example possible that the battery charging and discharging unit is furthermore arranged such that the minimum value is limited to vary in step a. and step b. only within a predetermined range. For example, the predetermined range for the minimum value may lie between of SoC of 30% and a SoC of 80%. This means that if for example in figure 3 in the period between t20 and t21 the local peak value would decrease under the second predetermined value 64 the minimum value representing the minimum SoC would not be increased because it has already reached its maximum of 80%. An example wherein the minimum value representing the minimum State of Charge of the battery is restricted to vary between 50% and 70% is shown in figure 4. Figure 4 shows clearly that within the periods between T=9 and T=20 the value representing the State of Charge of the battery is always smaller than the second predetermined value 64. Nevertheless the minimum State of Charge of the battery is not increased because it has already reached its maximum of 70%.
As already explained it holds for the embodiment of figure 3 that the battery charging and discharging unit is arranged such that in step a. the minimum value is decreased with a predetermined decrease value and/or such that in step b. the minimum value is increased with a
predetermined increase value. It moreover holds that the battery charging and discharging unit is arranged such that the predetermined increase value is fixed and/or that the predetermined decrease value is fixed. It is however also possible that the battery charging and discharging unit is arranged such that step a. comprises decreasing the minimum value with a rate which depends on the value representing the State of Charge of the battery and/or that step b. comprises increasing the minimum value with a rate which depends on the value representing the State of Charge of the battery. Examples include that step a. comprises decreasing the minimum value with a first rate which depends on the average, minimum or maximum of the value representing the State of Charge of the battery within at least one predetermined period and/or that step b. comprises increasing the minimum value with a second rate which depends on the average, minimum or maximum of the value representing the State of Charge of the battery within at least one predetermined period.
An example wherein in step a. the minimum value is decreased with a rate which depends on the value representing the State of Charge of the battery is shown in figure 5. In figure 5 it holds that if the value representing the state of charge of the battery at any time within a period exceeds both a first upper threshold 62.1 and a second upper threshold 62.2 than the first rate comprises steps of 6% of the Maximum SoC per period of time. If however the value representing the State of Charge of the battery lays between the first upper threshold 62.1 and the second upper threshold 62.2 then the minimum value relating to the minimum SoC of the battery is lowered with only 3% of the maximum SoC per period of time. Thus, for example, within the periods laying between t32 and t35 the rate wherein the minimum value representing the minimum SoC of the battery is decreased is equal to steps of 6% of the maximum SoC per period of time wherein for example in the periods laying between t30 and t32 the rate wherein the minimum value representing the minimum allowed SoC of the battery is decreased, corresponds with only 3% of the maximum SoC per period of time. Thus is holds that step a. comprises decreasing the minimum value with a first rate wherein in a step c. the first rate is increased if the value representing the State of Charge has increased in accordance with a first predetermined criteria and wherein the first rate is decreased if the first value representing the State of Charge has decreased in accordance with a second predetermined criteria. In this case the first predetermined criteria corresponds to the State of Charge of the battery increasing from a level between the first upper threshold and the second upper threshold to a level above both threshold 62.1 en 62.2 whereas the second criteria corresponds with the first value representing the State of Charge of the battery decreasing from a level above both the first upper threshold 62.1 and the second upper threshold 62.2 to a level between the first upper threshold 62.1 and the second upper threshold 62.2.
An example wherein in step b. the minimum value is increased with a second rate which depends on the value representing the State of Charge of the battery is also shown in figure 5. In figure 5 it holds that if the value representing the state of charge of the battery at any time within a period is smaller than both a first lower threshold 64.1 and a second lower threshold 64.2 than the second rate for increasing the minimum value comprises steps of 10 % of the Maximum SoC per period of time. If however the value representing the State of Charge of the battery is on a level laying between the first lower threshold 64.1 and the second lower threshold 64.2 then the minimum value relating to the minimum SoC of the battery is increased with only 5% of the maximum SoC per period of time. Thus, for example, within the periods laying between t5 and t7 the rate wherein the minimum value representing the minimum SoC of the battery is increased is equal to steps of 10% of the maximum SoC per period of time wherein for example in the periods laying between t36 and t38 the rate wherein the minimum value representing the minimum allowed SoC of the battery is increased, corresponds with only 5% of the maximum SoC per period of time. Thus it holds that step b. comprises increasing the minimum value with a second rate wherein in a step d. the second rate is increased if the value
representing the State of Charge has decreased in accordance with a third predetermined criteria and wherein the second rate is decreased if the first value representing the State of Charge has increased in accordance with a fourth predetermined criteria. In this case the third predetermined criteria corresponds to the State of Charge of the battery decreasing from a level between the first lower threshold 64.1 and the second lower threshold 64.2 to a level below both the first lower threshold 64.1 and the second lower threshold whereas the fourth criteria corresponds with the first value representing the State of Charge of the battery increasing from a level below both the first lower threshold 64.1 and the second lower threshold 64.2 to a level between the first lower threshold 64.1 and the second lower
threshold.64.2. Furthermore it holds for the example of figure 5 that the allowed first value of the minimum SOC is in the range of 30% to 80% of the maximum SOC of the battery
Other variations are also possible. Criteria (or combinations of these criteria) that can be used in the method to determine the rate of increase or decrease of the minimum value representing the minimum SoC are for example:
· rate as a function of the average value of the value representing the SoC in a predefined period or periods
• rate as a function of the weighted average value of the value representing the SoC in a predefined period or periods, where the weight factors can be depending on for example time and/or SoC level · rate as a function of the time the value representing the SoC is above or below a threshold
• rate as a function of the distance of minimum or maximum or average SoC during a period to the threshold
• rate as a function of the time in the year and/or day
· rate as a function of the age of the battery
• rate as a function of the expected power generation for the upcoming period(s)
In addition each of the above referred to thresholds can be variable based on for example:
· thresholds as a function of the time in the year and/or day
• thresholds as a function of the age of the battery
In the example of figure 6 the value representing the minimum SoC is increased if the average state of charge is below a predefined threshold 63 and the rate of increase of the minimum SoC limitation depends on the distance of the average SoC within a predetermined time period to this predefined threshold 63. The value representing the minimal SoC is decreased if the peak value of the SoC exceeds a predefined limit 62 for at least one hour and the minimum SoC reached is within a predefined distance from the value representing the minimum SoC.
In accordance with a special embodiment it holds that the battery charging and discharging unit is arranged such that the minimum value is decreased if necessary for enabling that the electric energy generated by the power generating means in a first predetermined collection of periods of the predetermined periods can be stored in the battery in a second
predetermined collection of periods of the predetermined periods wherein each of the periods of the second collection is later then each of the periods of the first collection.
Also according to a special embodiment it holds that the battery charging and discharging unit is arranged such that the minimum value is increased if necessary for enabling that the electric energy generated by the power generating means in a third predetermined collection of periods of the predetermined periods can be stored in the battery in a fourth
predetermined collection of periods of the predetermined periods wherein each of the periods of the third collection is later then each of the periods of the fourth collection and wherein after storing the electric energy in the battery the battery is loaded to a predetermined value representing the State of Charge.
It is noted that the battery charging and discharging unit 19 has been described in combination with figure 1. It is however also possible that the battery charging and discharging unit is not used in a system according to figure 1. It may be used in other systems wherein it is required to discharge and charge a battery. Furthermore, it is noted that in each of the embodiments discussed below it is the charging and discharging unit which regulates the minimum value representing a minimum allowed State of Charge of the battery, the rate wherein the minimum value is varied, the limits between which the minimum value is varied, stopping a discharge of the battery if the value representing the SoC of the battery reaches the allowed minimum SoC, etc. In accordance with the invention this
regulation and the other regulation as discussed above, may however also be carried out by a part of the system not being the charging and discharging unit itself. Thus this regulation may for example be carried out by the control means 16 of figure 1. In that case the battery charging and
discharging unit supplies via line 32 information to the control means about the actual value representing the State of Charge of the battery wherein the control means for example checks whether or not a step a. or step b should be carries out or whether the minimum value representing the allowed minimum SoC can remain unchanged. If for example a step a. or a step b. should be carried out, this is carried out by the control means 16 itself.
Based on the minimum value the control means may for example control the battery charging and discharging unit 19 via line 32 to stop discharging the battery 4 if the SoC of the battery reaches the minimum allowed SoC. Thus in that case the intelligence to carry out the above described method is present within the control means. It is also possible that the system according to figure 1 is arranged to switch off the charging and discharging unit if the State of Charge (SoC) of the battery remains during a
predetermined period below a predetermined value or if the minimum State of Charge (SoC) raises above a predetermined value, for example during a predetermined length of time. This could be done under the control of control means 16.
It is also possible that the system according to figure 1 is arranged to switch off the charging and discharging unit if it is detected by means of the system that the power submitted by a energy generating unit to the energy generating unit is below a predetermined value or is below a predetermined value during an predetermined length of time. This could be done under the control of control means 16. Such varieties each fall within the scope of the invention. It is noted that the invention is described by means of an example of a system according to figure 1. The invention however also lies within the battery charging and discharging unit 20 as such. This battery charging and discharging unit can also be used as a stand alone unit for charging and discharging the battery and it may be incorporated in other known and future systems wherein batteries are charged and discharged.

Claims

Claims
1. Method for controlling transfer of electric energy in to and out at least one rechargeable battery comprising setting a minimum value representing an allowed minimum State of Charge (SoC) of the battery wherein a discharging of the battery is stopped if a value representing the State of Charge of the battery reaches the minimum value representing the minimum State of Charge of the battery, characterized in that, the method comprises varying the minimum value as a function of a value representing the State of Charge of the battery wherein the function is such that the minimum value is decreased at least if within a predetermined period the value representing the State of Charge exceeds a first predetermined minimum requirement and the minimum value is increased at least if during a predetermined period the value representing the State of Charge does not exceed a second predetermined minimum requirement wherein the second predetermined minimum requirement corresponds with a lower State of Charge of the battery then the first predetermined minimum requirement.
2. Method for controlling transfer of electric energy in to and out at least one rechargeable battery comprising setting a minimum value representing an allowed minimum State of Charge (SoC) of the battery wherein a discharging of the battery is stopped if a value representing the State of Charge of the battery reaches the minimum value representing the minimum State of Charge of the battery, characterized in that, the value representing the minimum State of Charge of battery is changed such that local peaks in the variations in time of the value representing the State of Charge of the battery lay between a first predetermined value and a second predetermined value.
3. Method according to claim 1 or 2 wherein the method comprises at least the following steps:
- a step a. wherein the minimum value is decreased;
- a step b. wherein the minimum value is increased; wherein
step a. is carried out if within at least a first predetermined period of time a value representing the State of Charge of the battery is at least for one moment in time larger then a first predetermined value; and wherein step b. is carried out if within at least a second predetermined period of time the value representing the State of Charge of the battery is at least during a predetermined length of time smaller than a second predetermined value wherein preferably the first predetermined period of time is the second predetermined period of time.
4. Method according to claim 3, characterized in that step b. is carried out if within the at least the second predetermined period of time the value representing the State of Charge of the battery is always smaller than the second predetermined value.
5. Method according to claim 3 or 4, characterized in that, if within at least the first predetermined period of time the value representing the State of Charge of the battery is at least for one moment in time larger than or equal to the first predetermined value, then step a. is also carried out and/or if within at least the second predetermined period of time the value representing the State of Charge of the battery is always or at least during a predetermined length of time smaller than or equal to the second
predetermined value, then step b. is also carried out.
6. Method according to any preceding claim, characterized in that the controlling of the transfer of electric energy takes place in subsequent predetermined periods in time,
wherein step a. is carried out if within any predetermined period of a predetermined collection of the predetermined periods a value representing the State of Charge of the battery is larger than the first predetermined value and optionally also if within any predetermined period of the predetermined collection of the predetermined periods a value representing the State of Charge of the battery is equal to the first predetermined value, wherein step a. comprises decreasing the minimum value in a next predetermined period.
7. Method according to claim 6, characterized in that step b. is carried out if within any predetermined period of a predetermined collection of the predetermined periods the value representing the State of Charge of the battery is at least during predetermined length of time smaller than the second predetermined value and optionally also if within any predetermined period of the predetermined collection of the predetermined periods a value representing the State of Charge of the battery is at least during a predetermined length of time equal to or smaller than the second
predetermined value, wherein step b. comprises increasing the minimum value in a next predetermined period.
8. Method according to claim 7, characterized in that step b. is carried out if within any predetermined period of the predetermined collection of the predetermined periods the value representing the State of Charge of the battery is always smaller than the second predetermined value and optionally also if within any predetermined period of the predetermined collection of the predetermined periods a value representing the State of Charge of the battery is always equal to or smaller than the second predetermined value.
9. Method according to claim 6, 7or 8, characterized in that step a. is carried out if during any moment in time within any predetermined period of a predetermined collection of the predetermined periods a value representing the State of Charge of the battery is larger than the first predetermined value and optionally also if during any moment in time within any predetermined period of a predetermined collection of the predetermined periods a value representing the State of Charge of the battery is equal to the first predetermined value.
10. Method according to claim 6, 7 or 8, characterized in that step a. is carried out if during at least a predetermined length of time within any predetermined period of a predetermined collection of the predetermined periods a value representing the State of Charge of the battery is larger than the first predetermined value and optionally also if during at least the predetermined length of time within any predetermined period of the predetermined collection of the predetermined periods a value representing the State of Charge of the battery is equal to the first predetermined value.
11. Method according to any preceding claim, characterized in that, the minimum value is limited to vary in step a. and step b. within a predetermined range.
12. Method according to any preceding claim, characterized in that, in step a. the minimum value is decreased with a predetermined decrease value and/or that in step b. the minimum value is increased with a predetermined increase value.
13. Method according to claim 10, characterized in that the
predetermined increase value is fixed and/or that the predetermined decrease value is fixed.
14. Method according to any preceding claim 3-11, characterized in that, step a. comprises decreasing the minimum value with a rate which depends on the value representing the State of Charge of the battery and/or that step b. comprises increasing the minimum value with a rate which depends on the value representing the State of Charge of the battery.
15. Method according to claim 14, characterized in that step a.
comprises decreasing the minimum value with a first rate wherein in a step c. the first rate is increased if the value representing the State of Charge has increased in accordance with a first predetermined criteria and wherein the first rate is decreased if the first value representing the State of Charge has decreased in accordance with a second predetermined criteria and/or that step b. comprises increasing the minimum value with a second rate wherein in a step d. the second rate is increased if the first value
representing the State of Charge has decreased in accordance with a third predetermined criteria and wherein the second rate is decreased of the first value representing the State of Charge has increased in accordance with a fourth predetermined criteria.
16. Method according to any preceding claim 6-10, characterized in that use is made of power generating means connected to the battery wherein the minimum value is decreased if necessary for enabling that the electric energy generated by the power generating means in a first predetermined collection of periods of the predetermined periods can be stored in the battery in a second predetermined collection of periods of the predetermined periods wherein each of the periods of the second collection is later than each of the periods of the first collection.
17. Method according to any preceding claim 6-10 or 16, characterized in that use is made of at least one power generating means connected to the battery wherein the minimum value is increased if necessary for enabling that the electric energy generated by the power generating means in a third predetermined collection of periods of the predetermined periods can be stored in the battery in a fourth predetermined collection of periods of the predetermined periods wherein each of the periods of the third collection is later than each of the periods of the fourth collection and wherein after storing the electric energy in the battery the battery is loaded to a
predetermined value representing the State of Charge.
18. Method according to any preceding claim 3-17, characterized in that if the conditions for carrying out step a. are not met and the conditions for carrying out step b. are not met, then the minimum value remains unchanged.
19. Battery charging and discharging unit arranged to be connected to a battery for controlling the charging and discharging of the battery, characterized in that the charging and discharging unit is further arranged to carry out a method according to any preceding claim.
20. Battery charging and discharging unit arranged to be connected to a battery for controlling transfer of electric energy in to and out at least one rechargeable battery wherein the battery charging and discharging unit is arranged for setting a minimum value representing an allowed minimum State of Charge (SoC) of the battery wherein a discharging of the battery is stopped by the battery charging and discharging unit if a value representing the State of Charge of the battery reaches the minimum value representing the minimum State of Charge of the battery, characterized in that, the battery charging and discharging unit is further arranged for , varying the minimum value as a function of a value representing the State of Charge of the battery, wherein the function is such that the minimum value is decreased at least if within a predetermined period the value representing the State of Charge exceeds a first predetermined minimum requirement and the minimum value is increased at least if during a predetermined period the value representing the State of Charge does not exceed a second predetermined minimum requirement wherein the second predetermined minimum requirement corresponds with a lower State of Charge of the battery then the first predetermined minimum requirement.
21. Battery charging and discharging unit arranged to be connected to a battery for controlling transfer of electric energy in to and out at least one rechargeable battery wherein the battery charging and discharging unit is arranged for setting a minimum value representing an allowed minimum State of Charge (SoC) of the battery wherein a discharging of the battery is stopped by the battery charging and discharging unit if a value representing the State of Charge of the battery reaches the minimum value representing the minimum State of Charge of the battery, characterized in that, the battery charging and discharging unit is arranged such that the value representing the minimum State of Charge of battery is changed such that local peaks in the variations in time of the value representing the State of Charge of the battery lay between a first predetermined value and a second predetermined value.
22. Battery charging and discharging unit according to claim 20 or 21 wherein the battery charging and discharging unit is arranged to carry out at least the following steps:
- a step a. wherein the minimum value is decreased;
- a step b. wherein the minimum value is increased; wherein the battery charging and discharging unit is arranged such that
step a. is carried out if within at least a first predetermined period of time a value representing the State of Charge of the battery is at least for one moment in time larger than a first predetermined value; and wherein the battery charging and discharging unit is arranged such that
step b. is carried out if within at least a second predetermined period of time the value representing the State of Charge of the battery is at least during a predetermined length of time smaller than a second predetermined value wherein preferably the first predetermined period of time is the second predetermined period of time.
23. Battery charging and discharging unit according to claim 22, characterized in that the battery charging and discharging unit is arranged to carry out step b. if within the at least the second predetermined period of time the value representing the State of Charge of the battery is always smaller than the second predetermined value.
24. Battery charging and discharging unit according to claim 22 or
23, characterized in that, the battery charging and discharging unit is arranged such that if within at least the first predetermined period of time the value representing the State of Charge of the battery is at least for one moment in time larger than or equal to the first predetermined value, then step a. is also carried out and/or such that if within at least the second predetermined period of time the value representing the State of Charge of the battery is always or at least during a predetermined length of time smaller than or equal to the second predetermined value, then step b. is also carried out.
25. Battery charging and discharging unit according to any preceding claim 22-24, characterized in that, the battery charging and discharging unit is arranged such that the controlling of the transfer of electric energy takes place in subsequent predetermined periods in time, wherein the battery charging and discharging unit is arranged such that step a. is carried out if within any of the predetermined periods a value representing the State of Charge of the battery is larger than the first predetermined value and optionally also if within any of the predetermined periods a value representing the State of Charge of the battery is equal to the first predetermined value, wherein step a. comprises decreasing the minimum value in a next period.
26. Battery charging and discharging unit according to claim 25, characterized in that the battery charging and discharging unit is arranged such that step b. is carried out if within any of the predetermined periods the value representing the State of Charge of the battery is at least during predetermined length of time smaller than the second predetermined value and optionally also if within any of the periods a value representing the State of Charge of the battery is at least during predetermined length of time equal to or smaller than the second predetermined value, wherein step b. comprises increasing the minimum value in a next period.
27. Battery charging and discharging unit according to claim 26, characterized in that the battery charging and discharging unit is arranged such that step b. is carried out if within any of the predetermined periods the value representing the State of Charge of the battery is always smaller than the second predetermined value and optionally also if within any of the periods a value representing the State of Charge of the battery is always equal to or smaller than the second predetermined value.
28. Battery charging and discharging unit according to claim 25, 26 or 27, characterized in that the battery charging and discharging unit is arranged such that step a. is carried out if during any moment in time within any of the predetermined periods a value representing the State of Charge of the battery is larger than the first predetermined value and optionally also if during any moment in time within any of the
predetermined periods a value representing the State of Charge of the battery is equal to the first predetermined value.
29. Battery charging and discharging unit according to claim 25, 26 or 27, characterized in that the battery charging and discharging unit is arranged such that step a. is carried out if during at least a predetermined length of time within any of the predetermined periods a value representing the State of Charge of the battery is larger than the first predetermined value and optionally also if during at least the predetermined length of time within any of the predetermined periods a value representing the State of Charge of the battery is equal to the first predetermined value.
30. Battery charging and discharging unit according to any preceding claim 22-29, characterized in that, the battery charging and discharging unit is arranged such that the minimum value is limited to vary in step a. and step b. within a predetermined range.
31. Battery charging and discharging unit according to any preceding claim 22-30, characterized in that, the battery charging and discharging unit is arranged such that in step a. the minimum value is decreased with a predetermined decrease value and/or such that in step b. the minimum value is increased with a predetermined increase value.
32. Battery charging and discharging unit according to claim 31, characterized in that the battery charging and discharging unit is arranged such that the predetermined increase value is fixed and/or that the predetermined decrease value is fixed.
33. Battery charging and discharging unit according to any preceding claim 22-30, characterized in that, the battery charging and discharging unit is arranged such that step a. comprises decreasing the minimum value with a rate which depends on the value representing the State of Charge of the battery and/or that step b. comprises increasing the minimum value with a rate which depends on the value representing the State of Charge of the battery.
34. Battery charging and discharging unit according to claim 33, characterized in that the battery charging and discharging unit is arranged such that step a. comprises decreasing the minimum value with a first rate wherein in a step c. the first rate is increased if the value representing the State of Charge has increased in accordance with a first predetermined criteria and wherein the first rate is decreased if the first value representing the State of Charge has decreased in accordance with a second
predetermined criteria and/or such that step b. comprises increasing the minimum value with a second rate wherein in a step d. the second rate is increased if the first value representing the State of Charge has decreased in accordance with a third predetermined criteria and wherein the second rate is decreased of the first value representing the State of Charge has increased in accordance with a fourth predetermined criteria.
35. Battery charging and discharging unit according to any preceding claim 25-29, characterized in that the battery charging and discharging unit is arranged such that the minimum value is decreased if necessary for enabhng that the electric energy generated by the power generating means in a first predetermined collection of periods of the predetermined periods can be stored in the battery in a second predetermined collection of periods of the predetermined periods wherein each of the periods of the second collection is later than each of the periods of the first collection.
36. Battery charging and discharging unit according to any preceding claim 25-29 or 35, characterized in that the battery charging and
discharging unit is arranged such that the minimum value is increased if necessary for enabling that the electric energy generated by the power generating means in a third predetermined collection of periods of the predetermined periods can be stored in the battery in a fourth
predetermined collection of periods of the predetermined periods wherein each of the periods of the third collection is later than each of the periods of the fourth collection and wherein after storing the electric energy in the battery the battery is loaded to a predetermined value representing the State of Charge.
37. Battery charging and discharging unit according to any preceding claim 22-36, characterized in that, the battery charging and discharging unit is arranged such that if the conditions for carrying out step a. are not met and the conditions for carrying out step b. are not met, then the minimum value remains unchanged.
38. System comprising , a power generating unit connector which can be connected with a power generating unit, a battery charging and discharging unit according to any preceding claim 20-37 and a load connector which can be connected with a load, wherein the power generating unit connector, the battery charging and discharging unit and the load connector are connected to each other for the transfer of electric energy between the power generating unit connector, the battery charging and discharging unit and the load connector and wherein the battery, in use, is connected to the battery charging and discharging unit for charging and discharging the battery wherein the system is adapted to submit, in use, electric energy from the power generating unit connector to the load connector and/or the battery charging and discharging unit for charging the battery and wherein the system is adapted to submit electric energy from the battery via the charging and discharging unit to the at least one load connector.
39. System comprising a power generating unit connector which can be connected with a power generating unit, a battery charging and discharging unit which can be connected with a battery and a load connector which can be connected with a load, wherein the power generating unit connector, the battery charging and discharging unit and the load connector are connected to each other for the transfer of electric energy between the power generating unit connector, the battery charging and discharging unit and the load connector and wherein, in use, the battery is connected to the battery charging and discharging unit for charging and discharging the battery wherein the system is adapted to submit electric energy from the power generating unit connector to the load connector and/or the battery charging and discharging unit for charging the battery and wherein the system is adapted to submit, in use, electric energy from the battery via the charging and discharging unit to the at least one load connector,
characterized in that the system is arranged for carrying out the method according to any preceding claim 1-19.
40. System comprising, a power generating unit connector which can be connected with a power generating unit, a battery charging and discharging unit which can be connected with a battery and a load connector which can be connected with a load, wherein the power generating unit connector, the battery charging and discharging unit and the load connector are connected to each other for the transfer of electric energy between the power generating unit connector, the battery charging and discharging unit and the load connector and wherein the battery is connectable to the battery charging and discharging unit for charging and discharging the battery wherein the system is adapted to submit electric energy from the power generating unit connector to the load connector and/or the battery charging and discharging unit for charging the battery and wherein the system is adapted to submit electric energy from the battery via the charging and discharging unit to the at least one load connector, wherein system is arranged for setting a minimum value representing an allowed minimum State of Charge (SoC) of the battery wherein a discharging of the battery is stopped by the battery charging and discharging unit if a value representing the State of Charge of the battery reaches the minimum value representing the minimum State of Charge of the battery, characterized in that, the system is further arranged for, varying the minimum value as a function of a value representing the State of Charge of the battery, wherein the function is such that the minimum value is decreased at least if within a predetermined period the value representing the State of Charge exceeds a first predetermined minimum requirement and the minimum value is increased at least if during a predetermined period the value representing the State of Charge does not exceed a second predetermined minimum requirement wherein the second predetermined minimum requirement corresponds with a lower State of Charge of the battery then the first predetermined minimum requirement; or in that the system is arranged such that the value representing the minimum State of Charge of battery is changed such that local peaks in the variations in time of the value representing the State of Charge of the battery lay between a first predetermined value and a second predetermined value.
41. System according to claim 40 wherein the system is arranged to carry out at least the following steps:
- a step a. wherein the minimum value is decreased;
- a step b. wherein the minimum value is increased; wherein the system is arranged such that
step a. is carried out if within at least a first predetermined period of time a value representing the State of Charge of the battery is at least for one moment in time larger than a first predetermined value; and wherein the system is arranged such that
step b. is carried out if within at least a second predetermined period of time the value representing the State of Charge of the battery is at least during a predetermined length of time smaller than a second predetermined value wherein preferably the first predetermined period of time is the second predetermined period of time.
42. System according to claim 41, characterized in that the system is arranged to carry out step b. if within the at least the second predetermined period of time the value representing the State of Charge of the battery is always smaller than the second predetermined value.
43. System according to claim 41 or 42, characterized in that, the system is arranged such that if within at least the first predetermined period of time the value representing the State of Charge of the battery is at least for one moment in time larger than or equal to the first predetermined value, then step a. is also carried out and/or such that if within at least the second predetermined period of time the value representing the State of Charge of the battery is always or at least during a predetermined length of time smaller than or equal to the second predetermined value, then step b. is also carried out.
44. System according to any preceding claim 40-43, characterized in that, the system is arranged such that the controlling of the transfer of electric energy takes place in subsequent predetermined periods in time, wherein the system is arranged such that step a. is carried out if within any of the predetermined periods a value representing the State of Charge of the battery is larger than the first predetermined value and optionally also if within any of the predetermined periods a value representing the State of Charge of the battery is equal to the first predetermined value, wherein step a. comprises decreasing the minimum value in a next period.
45. System according to claim 44, characterized in that the system is arranged such that step b. is carried out if within any of the predetermined periods the value representing the State of Charge of the battery is at least during predetermined length of time smaller than the second predetermined value and optionally also if within any of the periods a value representing the State of Charge of the battery is at least during predetermined length of time equal to or smaller than the second predetermined value, wherein step b. comprises increasing the minimum value in a next period.
46. System according to claim 45, characterized in that the system is arranged such that step b. is carried out if within any of the predetermined periods the value representing the State of Charge of the battery is always smaller than the second predetermined value and optionally also if within any of the periods a value representing the State of Charge of the battery is always equal to or smaller than the second predetermined value.
47. System according to claim 44, 45 or 46, characterized in that the system is arranged such that step a. is carried out if during any moment in time within any of the predetermined periods a value representing the State of Charge of the battery is larger than the first predetermined value and optionally also if during any moment in time within any of the
predetermined periods a value representing the State of Charge of the battery is equal to the first predetermined value.
48. System according to claim 44, 45 or 46, characterized in that the system is arranged such that step a. is carried out if during at least a predetermined length of time within any of the predetermined periods a value representing the State of Charge of the battery is larger than the first predetermined value and optionally also if during at least the
predetermined length of time within any of the predetermined periods a value representing the State of Charge of the battery is equal to the first predetermined value.
49. System according to any preceding claim 41-48, characterized in that, the system is arranged such that the minimum value is limited to vary in step a. and step b. within a predetermined range.
50. System according to any preceding claim 41-49, characterized in that, the system is arranged such that in step a. the minimum value is decreased with a predetermined decrease value and/or such that in step b. the minimum value is increased with a predetermined increase value.
51. System according to claim 50, characterized in that the system is arranged such that the predetermined increase value is fixed and/or that the predetermined decrease value is fixed.
52. System according to any preceding claim 41-50, characterized in that, the system is arranged such that step a. comprises decreasing the minimum value with a rate which depends on the value representing the State of Charge of the battery and/or that step b. comprises increasing the minimum value with a rate which depends on the value representing the State of Charge of the battery.
53. System according to claim 52, characterized in that the system is arranged such that step a. comprises decreasing the minimum value with a first rate wherein in a step c. the first rate is increased if the value representing the State of Charge has increased in accordance with a first predetermined criteria and wherein the first rate is decreased if the first value representing the State of Charge has decreased in accordance with a second predetermined criteria and/or such that step b. comprises increasing the minimum value with a second rate wherein in a step d. the second rate is increased if the first value representing the State of Charge has decreased in accordance with a third predetermined criteria and wherein the second rate is decreased of the first value representing the State of Charge has increased in accordance with a fourth predetermined criteria.
54. System according to any preceding claim 44-49, characterized in that system is arranged such that the minimum value is decreased if necessary for enabling that the electric energy generated by the power generating means in a first predetermined collection of periods of the predetermined periods can be stored in the battery in a second
predetermined collection of periods of the predetermined periods wherein each of the periods of the second collection is later than each of the periods of the first collection.
55. System according to any preceding claim 44-49 or 54,
characterized in that the system is arranged such that the minimum value is increased if necessary for enabling that the electric energy generated by the power generating means in a third predetermined collection of periods of the predetermined periods can be stored in the battery in a fourth
predetermined collection of periods of the predetermined periods wherein each of the periods of the third collection is later than each of the periods of the fourth collection and wherein after storing the electric energy in the battery the battery is loaded to a predetermined value representing the State of Charge.
56. System according to any preceding claim 38-55, characterized in that, the system is arranged such that if the conditions for carrying out step a. are not met and the conditions for carrying out step b. are not met, then the minimum value remains unchanged.
57. System according to any preceding claim 38-56, characterized in that the system is further provided with a power grid connector which is connected with the power generating unit connector, the battery charging and discharging unit and the load connector for submitting energy from the power grid connector to the load connector and/or for submitting energy from the power generating unit connector and/or the battery charging and discharging unit to the power grid connector.
58. System according to claim any preceding claim 38-57,
characterized in that the system is further provided with a bus wherein the power generating unit connector, the battery charging and discharging unit and the load connector are connected to the bus for the transfer of electric energy from the power generating unit connector to the bus, from the battery charging and discharging unit to the bus and vice versa and from the bus to the load connector.
59. System according to claims 57 and 58, characterized in that the power grid connector is also connected to the bus for transferring electric energy from the bus to the power grid connector and vice versa.
60. System according to any preceding claim 38-59, characterized in that the system is arranged to provide electric energy to a building.
61. System according to claims 60, characterized in that the system comprises a load in the form of a local power grid of a building wherein the load is connected to the load connector.
62. System according to any preceding claim 38-61, characterized in that the system is provided with a power generating unit connected to the power generating unit connector wherein preferably the power generating unit is a solar panel or a windmill.
63. System comprising a battery charging and discharging unit according to any preceding claim 19-37 and a battery connected to the charging and discharging unit for charging and discharging the battery.
64. System according to any preceding claim wherein the system is arranged to switch off the charging and discharging unit if the State of Charge (SoC) of the battery remains during a predetermined period below a predetermined value or if the minimum State of Charge (SoC) raises above a predetermined value, for example during a predetermined length of time.
65. System according to any preceding claim wherein the system is arranged to switch off the charging and discharging unit if it is detected by means of the system that the power submitted by a energy generating unit to the energy generating unit is below a predetermined value or is below a predetermined value during an predetermined length of time.
PCT/NL2015/050029 2014-01-23 2015-01-16 Method for controlling transfer of electric energy into and out at least one rechargeable energy storage device WO2015112005A1 (en)

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Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009194947A (en) * 2008-02-12 2009-08-27 Kansai Electric Power Co Inc:The Charge/discharge depth management device and method, and power storage system

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009194947A (en) * 2008-02-12 2009-08-27 Kansai Electric Power Co Inc:The Charge/discharge depth management device and method, and power storage system

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