Patent Application
20210362614
The present invention relates to a solar powered electric vehicle charging station, and more particularly, to a charging station which receives solar sourced electricity and grid sourced electricity for storage, having a microprocessor center for controlling a load center which prioritizes the aggregated load to the electrical vehicles being charged by energy source.
There has recently been a surge of interest in using alternate energy sources to power transportation vehicles. This has been prompted by the public's concern for pollution and the eventual depletion of carbon base fuels presently used by most cars and trucks. After years of discussion and relatively slow development, major automobile manufacturers are finally producing plug-in hybrids and fully electrical vehicles (EV) models for public use. There are several models presently available, and the EVs typically have about 50-100 kilowatt-hour (kWh) of stored energy on board. This allows for one to two hundred miles of operation depending on terrain and driving conditions. The amount of time needed to fully recharge a EV's battery pack using the on-board charger ranges from four to eight hours. A lot of research and development is presently underway in EV battery technology to provide more onboard capacity and a faster recharge.
While electric cars have several potential benefits when compared to conventional internal combustion engines including a reduction in air pollution, several hurdles must be cleared before there will be wide spread public acceptance of them. An EV battery charging infrastructure must be developed which allows longer trips to destinations farther from home, and allows for a faster recharge. There is presently a national network of petroleum fueling stations along all highways for cars and trucks, but few of these have recharging stations for EVs.
Most EV batteries are now charged from AC energy at home supplied to the vehicle's on-board charger supplied by common US grounded house receptacles, commonly referred to as a 120 volt outlets. This process is known as Level 1 recharging, and it requires several hours. This method has fair acceptable since recharging can be done at home overnight, however, it limits the vehicle's use to local driving of short trips. More recently there has been a trend where some employers and some cities provide access to Level 2 chargers. These are faster since they use 220 volt outlets, but still require four to six hours which is acceptable if the EV owner is working or shopping. Several companies offer various models of Level 2 charging stations which are placed at work sites or designated areas in cities. Different models offer features as flexible pricing for time of day and kWh used; some offer wait list programs. Still these require several hours for recharging, and more importantly, use totally grid electricity.
A Level 3 charging infrastructure needs to be developed for longer trips, and faster charging. A Level 3 charger uses DC energy from off-board chargers and can provide up to 50 kW energy (300-600 V DC) providing a “quick” recharge. Quick charge systems require a more powerful DC electricity supply and suitable connectors as a SAE J1772-2009 connector which can provide around 18 kW/hr or a VDE-AR-E 2623-2-2 connector which can provide up to 44 kW/hr. Recharging typically takes a battery pack from around 10% to 80% battery capacity. As an example, taking a 50 kW battery pack from 10% to 80% capacity would require 35 kW energy which if provided by a 18 kW supply would take about 2 hours. However, there is a potential problem removing large amounts of electricity over a short period from the grid which must be solved. A typical US household draws about 1.5 kW power. A multi-vehicle quick charge station operating at full capacity could pull in excess of 50 kWh would adversely affect the local power supply if only transmission grid electricity were being used to supply the charging station. Removing that much electricity in that amount of time from the grid would most likely result in a local brown-out.
If the charging station infrastructure relies solely on transmission grid supplied electricity, very little net gain is made in reducing the carbon footprint in the atmosphere since approximately 80% of the electricity generated for the grid is from fossil fuels of coal and petroleum which produce carbon pollutants. If a reduction in atmospheric carbon is indeed a goal of the electric vehicle movement, the charging infrastructure must include an alternate energy component including solar, wind, tidal, biomass, and others. Otherwise, the net result is only a transfer of pollution from metropolitan areas having many vehicles to rural areas where the grid generators are located. This is not acceptable.
The present disclosure includes a renewable energy component of solar energy. Solar power is the conversion of sunlight into electricity either directly using photovoltaic cells, or indirectly using concentrated solar power. These systems use solar panels with tracking systems to focus the sunlight in the solar panel into a beam. Wind and tidal systems use the kinetic energy in the moving wind or water as the fuel source.
Solar power is an intermittent energy source which depends on the weather during the day and is not available at night. When sunshine illumination intensity is weak, power production is low; when illumination intensity is stronger, power production is greater. The magnitude of illumination, and thus power production, is classified into four classes including strong, moderate, weak, and very weak. Solar panels produce significant amounts of power only during direct sunlight. In the present application the solar output is used immediately to charge EVs. In the event no EVs are being charged during solar production, the electricity can be stored in a battery for a short period, or put into the transmission grid through a metering program providing a credit.
Grid electricity, as well as alternate energy sourced electricity, can be stored in a storage medium as rechargeable batteries, molten slats, and pumped-storage hydroelectricity, and others. Rechargeable battery storage in the present disclosure could include storage batteries recycled from other EVs. Molten salts are an effective storage medium since they are inexpensive, but would not have application in the present disclosure. With pumped-storage technology water is pumped from a lower to higher elevation reservoir. The energy is recovered when needed by releasing the water to a hydroelectric power generator.
As the number of EVs increase each year, the need for an national infrastructure of EV charging stations (EVCS) intensifies. Equally important, a larger percentage of the electricity used to recharge the EVs must be sourced from renewable energy. Otherwise, there is only a transfer of air pollutants from major population centers where the most cars are located to rural areas where the grid generators are located. Not a good compromise.
Petroleum based vehicles typically obtain fuel from a network of fueling sites located along roadways throughout the nation. It follows that these would be ideal locations for EV charging sites, but to date this has not been economically feasible. As solar panel electrical output increases and electrical storage technology improves, this will change and an EVCS infrastructure will be developed. The present disclosure relates to an EVCS which uses a renewable energy source combined with stored grid energy to charge the EVs. A computer prioritizes the charging load by source in order of renewable, stored, and direct grid.
Premium 4×8 solar panels presently produce about 1.5 kWh daily in locations with five hours direct sunlight. To generate a significant amount of electricity for recharging a number of solar panels would need to be on site. This disclosure proposes placing the solar panels on the station canopies. Most petroleum fueling sites have canopies to protect their customers from the weather. At a mid-sized fueling site of 16 linear fueling positions, it is typical to have a canopy measuring 220×20 feet. A canopy of this size would have about 4,500 square feet flat roof surface for mounting solar panels. Approximately 140 solar panels could be located in this square footage. Other potential surface areas for solar panel mounting includes the flat roofs on buildings at the site, flat roofs of any other canopies connecting the major canopy to these buildings, as well as ground surface areas.
Since solar panel output depends on direct sunlight, solar production varies depending on geographic location. Premium solar panels produce about 300 watts per hour. If a site gets 5 hours direct sun daily, solar production would be about 1500 watts or 1.5 kWh. This is about 550 kWh of electricity per year per panel, or about 75,900 kWh annually for the example site of 140 panels. In todays market, this amount of electricity at commercial retail on-peak would be valued at about $10-12,000 per year.
Clearly a solar array at fueling station in most locations will not produce enough electricity alone to operate a public EV charging station. However, the present disclosure does include renewable energy as a percentage of the charging load. As the technology improves, the percentage of renewable will increase. If a charging station had two level 2 charging sites and two level 3 charging sites, it would be dispensing well over 50 kWh when charging at full capacity. Using present day solar panels on site in direct sun, maximum solar production would be 200-300 kWh daily. While the solar produced component does not completely support the system, it is a start and the amount of production will increase with improved technology; other renewable sources could be used with the system.
If 50 plus kW are removed from the local transmission grid in a short period, a local brown out would likely occur. For comparison a household uses about 1.5 kWh. A storage component is therefore needed. The present disclosure uses grid storage batteries to store electricity, where the batteries are recharged at night during off-peak hours when rates are cheapest, and the electricity is released on demand for EV charging during the day. Battery storage technology is evolving rapidly as a tremendous amount of research and development is occurring in this field. The Li-ion technology is projected to bring battery-production cost down to around $200/kWh in the near future.
The present disclosure uses state of the art grid storage technology and the batteries are recharged late at night while rates are lowest and there is little or no EV charging activity. The energy is used on demand for charging the next day when rates are maybe three times higher. As previously discussed, pulling large amounts of electricity at a local site from the transmission grid can cause local brown outs. Using a storage component in the charging load could prevent this. In the present disclosure a computer controlled load center prioritizes the aggregated load to the charging meter charging EVs in the order of solar sourced, from storage, and lastly directly from the grid. Also in the present disclosure, when solar energy is produced and there is no EV charging activity underway, the electricity is directed to the grid for credit.
The present invention relates to a MPCC controlled EVCS, and method thereof, having a load center for aggregating a charging load from a renewable energy source, an electrical energy storage source, and energy directly from the transmission grid when storage is depleted. The objective of the invention is to provide a method to maximize the use of an alternate energy source, and to use an energy storage system to prevent local browns out which can occur when large amounts of electricity are removed locally. The energy storage system is recharged off-peak when rates are cheapest and house hold usage lowest. In a preferred embodiment, the alternate energy source is solar power, in other embodiments the alternate energy source could be wind, tidal, or biomass, or a combination thereof.
To achieve the foregoing objectives, the EVCS uses a solar cell array to produce electricity, the solar panels are mounted on flat surfaces of canopies at petroleum fueling sites. The MPCC uses algorithms to prioritize the electrical content of the aggregated charging load from the load center in the order of renewable, stored, and direct grid which is used only when storage is depleted. The MPCC further causes the storage system to be recharged during off-peak hours Any solar production when no EVs are being charged is put in the grid for credit.
Accordingly, the primary objective of this invention is to provide an EVCS which has a renewable energy component in the charging load.
A further objective of this invention is to provide an EVCS which will not cause local brown outs which can result from removing too much energy from the grid during a short period of time.
A further objective of this invention is to provide an EVCS which uses solar energy as an alternate energy source in the aggregated the charging load.
A further objective of this invention is to provide an EVCS which uses a grid storage system to store electrical energy for use in the aggregated the charging load.
A further objective of this invention is to provide an EVCS which has a load center for prioritizing the charging load in the order of solar sourced, storage system sourced, and direct grid sourced.
A further objective of this invention is to provide an EVCS which recharges the storage system during off-peak hours when rates are cheapest and household usage lowest.
A further objective of this invention is to provide an EVCS which uses solar panels placed on flat surface of canopies at petroleum fueling sites.
Other features of the present invention will become evident from a consideration of the following patent drawings, which for a part of the specification.
Referring now to the drawings, and first to
The main electrical load center 12 also receives electricity from an energy storage system 14 which is connected to the load center 12 through DC-DC convertor 15 which stabilizes the electricity at a preset value. The load center 12 also receives electricity from the transmission grid 16 through AC-DC invertor 16. Invertor 16 inverts and stabilizes electricity flow between the two; meter 20 keeps track of electricity exchange between them. One function of the load center 20 is to deliver electricity from the grid 16 to the storage center 14 where it is stored and released on demand to charge EVs. The storage system 14 is recharged from the grid 16 very late at night (off peak) when rates are cheapest and household usage at its lowest. MPCC 19 controls the timing of the recharge of the storage system with a timing mechanism.
The load center 12 receives power from the solar cell 11, the storage system 14, and from the grid 16. The load center 12 aggregates power from these sources forming a charging load 23, and feeds the charging load to a smart charging meter 18. The MPCC 19 causes the load center 12 to prioritize the energy source of the aggregated charging load in the following order: solar, stored, and direct grid, The charging meter 18 distributes the power to the electric vehicles 21(ABC) through connectors 20(ABC). In practice there are several charging sites to service several vehicles 21(ABC). The charging meter 18 tracks the identification of each vehicle 21(ABC) connected to the system from charging. It collects data for each vehicle including vehicle ID, the date and time of charging, the amount of power delivered, and other pertinent information. This data is transferred from the charging meter 18 to a billing center 22 which may include an attendant in an adjacent service building, or it may be connected to a computer processing system for upload of the billing information. The charging meter 18 monitors the status of the charging process including battery temperature and capacity.
The charging meter 18 assesses the status of the charging process for each charging site 21(ABC). It determines when there is a new connection for a charge, the position, and when the charging is complete. The charging meter 18 determines the optimal voltage and currents needed to perform the charging task at each charging site. For illustrative purposes, there are three charging sites 21ABC in
MPCC 19 controls several task in the EVCS 10. It has a bi-directional connection to the load center 12, the charging meter 18, and the DC-DC convertor 13. It receives information from the charging meter 18 on the status of the charging mode for each charging site though feedback signals. The MPCC 19 receives power production information from the DC-DC convertor 13 including the amount of electricity being produced by the solar array. The MPCC 19 causes the load center 12 to prioritize the aggregated charging load to the smart charging meter 18 by electrical energy source where the priority is solar sourced, battery sourced, and direct grid sourced. The charging meter 18 assesses the status of the charging process for each vehicle 21(ABC) including optimal voltages and currents needed to perform the recharging task, and sends this information to the MPCC 19.
The MPCC 19 includes standard computer hardware as a MP, nonvolatile RAM with code, static RAW with data, ROM for operating the system, and bidirectional interfaces for modem connection and connection to various components of the charging system. It stores and processes look-up tables of data points. Algorithms set forth computational procedures to control several task including prioritizing the aggregated charging load to the charging meter 18 according to electricity source.
The load center 12 receives power from the solar cell 11, the storage system 14, and the grid 16. The MPCC 19 prioritizes the energy source aggregating the charging load. The charging meter 14 tracks the ID of each VE(ABC) connected to the system gathering data as amount of current delivered, time and date, and status of the charge. There is a bi-direction and exchange of transaction data with the billing system 20. The charging meter 18 also bi-directionally exchanges charging information with the MPCC 19. The information is used to assess the status of the charge including optical voltage and amps for the charge and when the charge is complete.
Grid storage systems typically store electrical energy when grid production exceeds demand, and then used when grid demand is greater than production, or it may come from renewable sources. In the present disclosure the electrical energy is taken for the grid, temporary stored, and then used on demand to charge EVs. This has two major advantage. First, the energy is removed from the grid very late at night when rates are low, and the energy is used during the day when rates are high; this allows the station to generate profitable revenue for operation. Second, it prevents local brown outs which can occur when large amounts of electricity are pulled from the grid during the day when household usage is high. If a charging station pulls from 50-100 kWh during the day a local brown out would most likely occur. Household usage is very low very late at night. Meter 24 keeps track and records all transfer of energy to and from the grid 16.
The present disclosure uses Li-ion technology for battery storage system 14. While battery production cost has been a major hurdle in storage technology, it is projected the Li-ion technology could bring battery production cost down to the $150/kWh range shortly. While there is some energy lost during the battery storage process, the savings from purchasing the energy at low rates and selling at high rates helps with the economics of this lost. Technology exist for the transfer of energy from the grid to a storage medium, the AC-DC invertor 17 is a key component. The MPCC 19 controls the time of transfer which is usually between 12-3:00 AM. The timing of transfer and Li-ion is not meant to be restrictive.
The load center 12 delivers the aggregated charging load 23 to the charging meter 18 which performs the charging task. The charging meter 18 individually delivers electricity to the charging connectors 20(ABC) which individually connect to EV21(ABC). It tracks the amount of electricity delivered to each vehicle during the charging session. The charging meter 18 is connected to a billing system 22 for collecting for the electricity dispensed.
The charging meter 18 bi-directionally exchanges capacity feedback information with each individual connector 20(ABC) for each charging site 219(ABC). This information includes new connection for charge, optimal voltage and current, and charge completed. Other data transferred to assess the status of the charge includes ID of the vehicle, date and time, amount of current dispensed, and related. Certain information is processed and sent to MPCC 19, other information is sent to a billing center 22 which may go through the MPCC 19 or it may be sent direct.
Referring now to
Referring now to
The load center 12 receives electrical energy from the solar cell 11, the energy storage system 14, and the grid 16. The MPCC 19 prioritizes the electrical input into the aggregated charging load 23 (which flows from the load center 12 to the smart charging meter 18) by the following order: solar, storage, direct grid. The net effect is that if any charging is occurring, all solar production is first used in aggregating the charging load which is then supplemented by storage energy. Energy directly from the grid is used for aggregating the charging load only when the stored energy is depleted.
Referring now to
If the storage center 14 is depleted of electrical energy and more is needed for charging, the aggregating process in block 54 defaults which directs to default block 58 which defers to flow chart 60. Referring now to
MPCC 19 instructs the load center 12 to recharge the electrical energy storage system 14 from the transmission grid 16, typically late at night from 12 to 3:00 AM. The MPCC 19 uses a timer process for causing energy to flow from the grid 16 to the load center 12, where the energy flows through AC-DC invertor 17 which conditions the current. Meter 20 tracks and records the flow of current between the two. The energy is transferred from the load center 12 to the storage center 14 through DC-DC converter 15 until the system is fully recharged. The 12-3:00 time period is off-peak when rates are cheapest and household usage is lowest; this decreases the chance of local brown out. The energy is used during on-peak hours when rates are highest. This timing is not meant to be restrictive since transfer could be at other times.
In a preferred embodiment of the present invention, the solar panels 11 are mounted on the top of canopies of petroleum fueling sites which are often located in high density areas where ground surface area is limited. These fueling sites most often have canopies to protect their customers from weather. Typically sixteen fueling position fueling sites have canopies measuring around 20 by 220 feet of flat surface which is ideal for mounting canopies since panels can be easily positioned toward the sun. Mounting panels on canopies is not meant to be restrictive; other surfaces including ground surface could be used in alternate embodiments.
The present disclosure uses solar panels mounted on petroleum fueling site canopies as the renewable energy source; certainly other alternate fuels including the kinetic energy in wind and water could be used with the present device, or any combination of solar, wind, water, and bio could be used.
The present invention may, of course, be carried out in ways other than those herein set forth without parting from the spirit and essential characteristics of the invention. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein. The term “at least one” is a term commonly used in claim language and usually allowed by the USPTO, meant to encompass a combination having either one or more than one stated elements.
