Patent Application
20160176302
The invention relates to electric vehicles, in particular to a wireless battery charging system and regenerative braking system that are to reduce the overall number of electrical components in the vehicle and allow two way wireless transmission of electrical power between the electrical vehicle and the utility grid.
The regenerative braking system in an electrical vehicle or hybrid electric vehicle converts direct current from the vehicle's batteries to an alternating current used by the motor/generator to propel the vehicle. The regenerative braking system also converts the alternating electrical current generated by the motor/generator while braking to a direct current that is used to recharge the vehicle's batteries using a rectifier circuit. Thus, some of the vehicle's kinetic energy can be conserved rather than employing friction brakes which convert the vehicle's kinetic energy to waste heat energy. The regenerative braking system is tuned to accommodate alternating current from the motor/generator typically in the 500 Hz to 10 kHz range.
Electrical vehicles have also incorporated wireless battery charging technology that transmits electrical power from an off vehicle battery charger to the vehicle without a direct wired connection between the charger and the vehicle. The battery charger converts electrical power from the utility grid having a frequency of 50 to 60 Hz to a higher frequency of 15 kHz to 150 kHz. The high frequency electrical current is transmitted to an off-vehicle transducer located near the electrical vehicle, e.g. underneath the vehicle, which generates an alternating magnetic field. A receiving coil located in the vehicle is magnetically or inductively coupled with the off-vehicle transducer and the magnetic field induces a high frequency alternating electrical current in the receiving coil. This alternating current is then converted to a direct current that is used to recharge the vehicle's batteries using a rectifier circuit is tuned to accommodate alternating current from receiving coil, typically in the 15 kHz to 150 kHz range.
The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also be inventions.
In accordance with an embodiment of the invention, a wireless battery charging system is provided. The wireless battery charging system includes an off-vehicle transducer that is electrically connected to a power source and configured to wirelessly transmit and receive a first alternating current having a first frequency, an on-vehicle transducer that is magnetically coupled to the off-vehicle transducer and is configured to wirelessly transmit and receive the first alternating current, and a frequency converting circuit that is disposed within a vehicle and is electrically connected to the on-vehicle transducer. The frequency converting circuit is configured to change the first frequency of the first alternating current to a second alternating current having a second frequency. The first frequency may be in a range of 500 Hz to 10 kHz and the second frequency may be in a range of 15 kHz to 150 kHz. The wireless battery charging system also includes a battery disposed within the vehicle and a regenerative braking circuit that is disposed within the vehicle and is electrically connected to the frequency converting circuit and the battery. The regenerative braking circuit is configured to rectify the second alternating current to a direct current supplied to the battery and is further configured to convert the direct current from the battery to the second alternating current supplied to the frequency converting circuit.
According to one embodiment of the invention, the wireless battery charging system has a first mode of operation in which the on-vehicle transducer wirelessly receives energy from the off-vehicle transducer to produce the first alternating current having the first frequency that is converted by the frequency converting circuit to the second alternating current having the second frequency that is than transmitted through the regenerative braking circuit to electrically charge the battery.
According to another embodiment of the invention, the frequency converting circuit is further configured to change the second frequency of the second alternating current to the first alternating current having the first frequency. In this embodiment, the wireless battery charging system has a second mode of operation in which the battery transmits a direct electrical current through the regenerative braking circuit to supply the second alternating current having the second frequency that is then converted by the frequency converting circuit to the first alternating current having the first frequency which is transmitted through the on-vehicle transducer to wirelessly transmit energy to the off-vehicle transducer, thereby transmitting through the power source to a utility grid.
According to other embodiments of the invention, the first mode of operation or the second mode of operation are selected by the wireless battery charging system. The wireless battery charging system's operation is controlled by user selection of the first mode of operation or the second mode of operation, and a condition selected from the list consisting of:
(a) battery state of charge data,
(b) battery state of health data, and
(c) an on/off state of the wireless battery charging system.
Electrical charging of the battery may be based on user selection of the first mode of operation or the second mode of operation and the conditions listed above. Alternatively, the wireless battery charging system may operate in the first mode of operation or the second mode of operation based on a data received by the wireless battery charging system from a utility grid management facility.
According to another embodiment, the wireless battery charging system further includes an RF data link that is electrically connected to the battery and is configured to wireles sly transmit battery state of charge data and/or battery state of health data to the power source.
The present invention will now be described, by way of example with reference to the accompanying drawings, in which:
Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention which may be embodied in other specific structures. While a preferred embodiment has been described, the details may be changed without departing from the invention.
In order to lower the costs of producing and consuming electrical power, it may beneficial to generate and store electrical energy when the demand and/or generating costs are low and retrieve this energy for use when demand and the cost for electrical energy is high. A battery of an electric or hybrid electric vehicle may be utilized for this energy storage. For instance, the battery of the vehicle may be electrically charged during the nighttime hours when energy rates are low and, if the vehicle is not being used and if authorized by the vehicle owner, may be used to provide energy from the stored battery and for use in an energy utility grid when demand for the energy is high during daytime hours. In this scenario, an electrical utility may be able to monetize this energy sharing arrangement with the cooperation of the vehicle owner.
A wireless battery charging system that provides bidirectional energy flow between a utility grid and a battery in a vehicle is presented herein. A regenerative braking system is typically used in an electric vehicle or a hybrid electric vehicle. The regenerative braking system generates an alternating current from the direct current of the vehicle's battery and send the alternating current to the motor/generator to propel the vehicle. The regenerative braking system converts the actuating current from the motor/generator to a direct current that is supplied to the batteries to recapture some of the kinetic energy when the vehicle is braking. The regenerative braking system provides a bidirectional flow of electrical energy to and from the battery. The inventors realized that this bidirectional flow of electrical energy of the regenerative braking system could also be used in conjunction with elements of a wireless charging system. First, the regenerative braking system could rectify the alternating current output by the on-vehicle transducer to a direct current that could be used to charge the battery. This would allow the elimination of a separate rectifier circuit dedicated to the wireless charging system. Second, the regenerative braking system could convert the direct current from the battery to an alternating current that could be transmitted from the on-vehicle transducer to the off-vehicle transducer to provide the battery's stored energy to a power grid. However, since the alternating current used by the motor/generator and regenerative braking system and the alternating current used by the wireless charging system are typically within different frequency ranges, the inventors also realized that the inclusion of a frequency convertor circuit was desired.
A non-limiting example of a wireless battery charging system 10 is illustrated in
A third power flow PF3 is shown in
The wireless battery charging system 10 presented in
In order to take advantage of existing regenerative braking circuitry 26 that is configured to operating within a single frequency range of 500 Hz to 10 kHz, an embodiment may desired that includes a separate frequency converting circuit 72 as shown in
As further illustrated in
A data message sent from a utility grid facility (not shown) may command the wireless battery charging system 10 to operate in the second mode of operation wherein energy is transferred from the battery 12 to the utility grid 14. The wireless battery charging system 10 may be configured to allow the user 34 to inhibit the second mode of operation to occur, for example if the user 34 has a trip with the vehicle 16 planned in the near future. The operator or user 34 may make user-selectable mode selections for the wireless battery charging system 10 by cellular phone, PDA, personal computer, and the like.
The wireless battery charging system 10 presented herein provides using regenerative braking circuitry 26 on the vehicle 16 for both regenerative braking when the vehicle 16 is being driven and wireless charging when the vehicle 16 is stationary. This provides cost and packaging benefits for the vehicle 16 since there is no need for a separate rectifier dedicated to the wireless changing system since the rectifier can be shared for both braking and charging. The system also provides the benefits of storing and supplying power to a utility grid 14 from the vehicle's battery 12. This the benefits of generating and storing electrical energy when the demand and/or generating costs are low and retrieve this energy for use when demand and the cost for electrical energy is high. In this scenario, an electrical utility may be able to monetize this energy sharing arrangement with the cooperation of the vehicle owner. The system also provides benefits since the vehicle's inverter can be used both for powering the motor/generator 22 and providing power to the utility grid 14 without the need for additional circuitry being added to the vehicle, again saving component cost, vehicle packaging space, and vehicle mass.
While this invention has been described in terms of the preferred embodiments thereof, it is not intended to be so limited, but rather only to the extent set forth in the claims that follow. Moreover, the use of the terms first, second, etc. does not denote any order of importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items.
This application is a continuation-in-part application and claims benefit under 35 U.S.C. §120 of U.S. patent application Ser. No. 13/562,954, filed Jul. 31, 2012, which claims priority under 35 U.S.C. §119(e) of U.S. Provisional Patent Application No. 61/515,866, filed Aug. 6, 2011, the entire disclosure of each of which are hereby incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61515866 | Aug 2011 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 13562954 | Jul 2012 | US |
| Child | 15046728 | US |
