NL1037029C2 - METHOD AND DEVICE FOR WIRELESS CHARGING OF ELECTRIC VEHICLES. - Google Patents

Description

Method and device for wireless charging of electric vehicles

The present invention relates to a method or device for charging electric vehicles characterized by a first preferably coil-wound coil, means for generating an alternating magnetic and / or electric field, a second preferably coil-wound coil attached to a vehicle, means for converting an alternating magnetic and / or electric field into an alternating voltage, means for rectifying the alternating voltage, at least one battery or a capacitor and means for charging at least one battery or capacitor. The first and second coils are galvanically isolated from each other and, if desired, energy transfer occurs from the first coil 10 to the second coil. The energy transferred to the second coil is used to charge at least one capacitor or battery. The electrical energy stored in the battery is then used as an energy source for an electric vehicle.

Introduction 15 In the future, motor vehicles will for the most part, if not entirely, be provided by electric vehicles. One of the characteristics of electric cars is that the batteries in these cars must be recharged periodically. It is now thought to provide this by constructing a network of charging points where the connection between the car and the network is provided by an electrical wire through a power outlet.

The present invention provides for the wireless charging of batteries. A wireless concept has a number of major advantages over a traditional concept with wires and socket: it is safer, the charging points can be processed in the road surface or other objects, if a vehicle is stationary the charging can be fully automatic via an automated protocol. Charging can take place in traffic situations such as, for example, a bus that stops at a bus stop or a taxi at a taxi rank, and a car can, if desired, automatically supply electricity to the network.

The present invention is now described in detail. According to a first aspect, the present invention consists of a first, preferably spiral wound coil. This coil is preferably flat so that it can be built into objects that also fulfill another function such as a road surface or a wall of a building. According to a second aspect, the present invention consists of a function generator and an amplifier whose output is connected to the first coil. The frequency of the alternating voltage supplied by the function generator and the amplifier is preferably tuned to the characteristics of the coil, i.e. the inductance of the coil and, if relevant, also the capacitance of the coil. According to a third aspect, the present invention consists of a second coil-wound coil, which is preferably also flat, so that it can easily be installed in, for example, a vehicle. In this case, a vehicle is understood to include a car. The dimensions of the second spiral wound coil as well as the number of turns are adjusted to the frequency of the alternating voltage which is supplied to the first coil by the function generator and amplifier. According to a fourth aspect, the first and second coil are galvanically isolated from each other. According to a fifth aspect, in the present invention, the second coil is electrically connected to means for rectifying the alternating voltage generated in the second coil. According to a sixth aspect of the present invention, the rectified alternating voltage is directly or indirectly connected to at least one super capacitor or a battery. In this connection, indirect connection of the direct voltage to a super capacitor or a battery is understood to mean a microprocessor-controlled charger of a super capacitor or battery. According to a seventh aspect of the present invention, if desired, energy is transferred from the first coil to the second coil and, after rectification, this energy is used to charge at least one battery or capacitor which subsequently makes it possible to supply a consumer with electrical energy. .

Now that the core of the present invention has been described, a number of preferred embodiments follow.

In a first preferred embodiment, the function generator consists of a microprocessor 20 so that the frequency and amplitude can be adjusted by software depending on the load on the second spiral wound coil. The PIC16F84A is a non-limiting example of a microprocessor that can be used for this purpose. When a microprocessor is used as a function generator, the clock frequency of the microprocessor is used as a time base. Subsequently at least one output is set high or low by software alternating. Preferably 2 outputs are set alternately high and low. The outputs are then connected to an intermediate amplifier, for example a BC547B NPN transistor. The output of the transistor is used to supply a FET, for example of the IRF540 type. The FETs are connected to a spiral wound coil via a single ended or push pull circuit. When a push pull circuit is used as a driver, this spiral wound coil has a center tap to which the voltage source is connected, as is customary according to traditional push pull switching techniques. It is clear to a person skilled in the art that a function generator and amplifier obtained in this way is simple, can be produced at a low cost and is very flexible because the properties of the function generator can be set by software.

In a second preferred embodiment, the present invention consists of at least one flat spiral wound coil with a part of the number of turns on either side of a flat holder, such as a printed circuit board. The direction in which the windings are wound on either side of the coil is chosen such that the field generated by both coil parts runs in the same direction. The number of turns of the coil pieces on either side of the flat holder as well as the geometry of these coil parts is preferably the same on both sides. The coil parts on each side of the holder are connected to each other by a connection from the top to the bottom of the flat holder. In a push pull application, this interconnection is preferably used as the center tap of the coil.

In a third preferred embodiment, the technology according to the present invention 10 comprises at least one tuned circuit. This tuned circuit is realized by connecting at least one capacitor in series with or parallel to the first or the second, preferably coil-wound coil. It is noted that this capacitor can be omitted if such a coil geometry is chosen that the capacitance of the coil is sufficient to realize a tuned circuit at the frequency at which the function generator is set.

In a fourth preferred embodiment, the technology according to the present invention comprises at least one diode and preferably a diode bridge and capacitor for rectifying and smoothing the alternating voltage generated in the second coil. If high voltage is used, it is possible to opt for a pulsed direct voltage that is not smoothed off or only limited by means of a capacitor. It is clear to the skilled person that a pulsed high voltage with a sufficiently high frequency is less dangerous than a smoothed high voltage in which a large amount of energy is stored in high voltage capacitors. It is noted that this method can be particularly advantageous from an energy point of view in combination with charging a battery by means of direct current pulses. If a battery is charged, on the one hand a chemical reaction occurs and on the other hand ion transport and concentration polarization take place. During the charging process, a battery therefore behaves as a load resistor with a capacity. This capacity can be used to efficiently store electrical energy for a very short time when the battery 30 is charged via a pulsed direct current.

In a fifth preferred embodiment, the technology according to the present invention comprises a microprocessor which controls how much electrical power is taken off wirelessly via the first coil and which also controls a charging profile of a capacitor or battery connected to the second coil. It is clear to the person skilled in the art that this is relatively easy as the first and second coil are coupled and the load on the second coil is directly reflected in a greater power which is supplied by the amplifier to the first coil.

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In a sixth preferred embodiment, the technology according to the present invention comprises an intelligent communication system such as WiFi or RFID technology so that a consumer is automatically recognized as soon as it comes close to an electric charging station. If desired, a charging process is started automatically as soon as this is possible geometrically and from an energy efficiency perspective. It is noted that, in addition to Wi-Fi or RFID technology, it is also very possible to realize wireless communication between the consumer and the charging station via telephony, i.e. via GSM technology or via two-way radios. In addition, the application of ultrasonic vibrations, more specifically modulated ultrasonic vibrations, is extremely suitable for communication between consumer 10 and charging station. Furthermore, an information carrier can also be superimposed on the induction signal transferring the energy from the first to the second coil, for example by modulating the induction signal amplitude with a small modulation depth. It is clear to the skilled person that the communication density of a data exchange between consumer and charging station can remain low.

In a seventh preferred embodiment, the technology according to the present invention comprises means for measuring the current being transmitted and a circuit which limits the current or switches off the power supply if too much power is required. Means for measuring the current may for example consist of a coil which encloses the magnetic field with a current-carrying wire, a very small series resistance across which the voltage is measured or an ultrasonic sensor which measures the amplitude of the ultrasonic vibrations caused by the alternating current in the wire or eddy currents in a metal sensor.

In an eighth embodiment, means are arranged under a vehicle that prevent the efficiency of the energy transfer from the first coil to the second coil from being limited because eddy currents go into the metal chassis of the vehicle, in particular the sheet metal under the car. walk. On the one hand, such eddy currents can be limited by the choice of the correct frequency of the alternating voltage. Another method that may or may not be used in combination with a smart choice of the frequency of the alternating voltage is to increase the coupling between the first and the second coil between which the energy transfer takes place. The coupling between the first and the second coil can be increased by, for example, making use of ferrite located around and partly between the two coils. By choosing the geometry of the ferrite means according to the state of the art of transformer technology or by approximating such a situation as far as possible, the energy transfer from the first coil can be directed as much as possible to the second coil, as a result of which eddy currents in the chassis of the car are limited. It is noted that eddy currents in the chassis of the car are precisely desirable in some cases. Thus, with the technology according to the present invention, it is possible to keep the fuel in a vehicle at the correct temperature in a very automatic manner in very cold areas, i.e., in areas where there is a risk of diesel or other fuel freezing. For this purpose, a first coil is provided, for example under a parking space. When a car is parked in the parking lot, an amount of energy is then transferred via the first coil to the car's chassis. The maximum amount of energy that is transferred is limited by means of a protection, but is sufficient to keep the temperature of the chassis of the car above the freezing point of the fuel. Since in this case the chassis of the car is heated by the eddy currents in the metal, a second coil is not necessary. In short, this means that a car needs no adjustments to be used in combination with the present invention. A fuel heating system as described in this application explicitly forms part of the present invention.

In a ninth embodiment, the first coil is driven with a pulsed alternating voltage. Subsequently, different microprocessors are coupled to the secondary coil, each of which drives individual circuits at a carefully selected time relative to each other and which extract energy from the secondary coil. This creates a situation in which different consumers, including 20 batteries and / or capacitors, can be supplied with current simultaneously, while the load on coil 2 is optimal at any time.

In a tenth embodiment, a security code and wireless protocols prevent unauthorized use of the wireless energy supply and information is exchanged on the basis of which the consumer, whether or not automatically, opts for a charging session, is billed, supplies electricity to the grid if desired or behaves inertly towards the wireless energy system.

In an eleventh embodiment, from a central energy supply, i.e., a central power supply from the network, a network of first coils is supplied with alternating voltage. The amplitude of the alternating voltage applied to each coil is very small and each coil is in a "standby state". By means of a sensor system, which consists in the most rudimentary form of a series resistance per coil connection, it is measured from which coils electrical energy is taken. If a significant amount of energy is taken from a coil, this is a sign that an energy-using object has been placed on a parking space. A security code and wireless communication then determine whether the parked object qualifies for charging. If this is the case, the power is fed to the energy-transferring coil from the central energy supply by means of a microprocessor and the vehicle is supplied with energy. In this way, both a safe energy transfer is realized because the electrical and / or magnetic and / or electromagnetic radiation is concentrated between the transmitting coil (the first coil) and the receiving coil (the second coil) during charging. The radiation that is produced in the standby state is so small that it is not harmful. This amount of radiation, which is not harmful in itself, can be reduced even further by taking the standby measurement in very small time intervals, for example every five seconds for 5 microseconds, and switching off the system for the rest of the time.

In a twelfth embodiment, means in combination with the technology according to the present invention is applied to prevent interference in electrical circuits of the car under the influence of the electric and / or magnetic and / or electromagnetic field generated by the first coil (s). . The following are a non-exhaustive list of means for preventing interference: band filters in the final stage of the amplifier according to the present invention, a Faraday cage or an approximation thereof, energy transfer in a frequency range affecting the electrical circuits of the car and the remote control of does not affect the car. The energy transfer can be realized by means of an alternating voltage with a frequency in the range of 1 Hz to 10 GHz, preferably in the range of 1 kHz to 100 MHz, even more preferably in the range of 10 kHz to 20 MHz and most preferably in the range of 20 kHz to 10 MHz. Also energy transfer at several frequencies simultaneously is explicitly part of the present invention.

In a thirteenth embodiment the technology according to the present invention is applied in combination with one or more cylindrical first coils and / or spiral wound first coils and / or toroidal first coils and / or networks of these first coils one above the other and / or networks of these first coils one under the other and / or individual first coils one above the other and / or individual first coils next to each other and / or one or more cylindrical second coils and / or spiral wound second coils and / or toroidal second coils and / or networks of these second coils one above the other and / or networks of these second coils one after the other and / or individual second coils one above the other and / or individual second coils next to each other.

It is further noted that the technology according to the present invention can also be applied in combination with more traditional technologies. For example, the alternating voltage can be generated with classical oscillators including a Colpitts oscillator, a Hartley 35 oscillator, an oscillator based on a 555 timer IC but not limited thereto.

Finally, it is noted that the term vehicle in the present invention should be interpreted broadly, i.e. as movable objects. Vacuum cleaners, lawn mowers, 7 cleaning equipment for swimming pools, reconnaissance aircraft, golf carts, electric boats, fairground attractions, laptops, PDAs, mobile phones, power tools, forklifts and cleaning equipment are non-limiting examples of vehicles according to the definition of the present invention.

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Claims (7)

Device for wirelessly transferring electrical energy to a vehicle characterized by: • Means for generating an alternating voltage or a pulsed direct voltage or a combination thereof • An amplifier with at least one power transistor including a FET in the final stage • A first coil electrically connected to the amplifier's final stage 10. A second coil that is galvanically isolated from the first coil and which is connected to a load resistor • Means to rectify the alternating voltage across the second coil • A load resistor consisting at least in part of a capacitor or a battery or both Device as claimed in claim 1, wherein the amplifier consists of at least one push-pull output stage. Device according to one of the preceding claims 1 and 2, wherein the means for generating the alternating voltage or pulsed direct voltage comprises at least one microprocessor. Device according to one of the preceding claims 1 to 3, wherein the microprocessor alternately switches on and off at least 2 logic outputs and provides a signal to send current through a coil in accordance with a push-pull principle. 5. Device as claimed in any of the foregoing claims 1-4, wherein information is exchanged via a wireless protocol between the device connected to the first coil and the device connected to the second coil and wherein the nature of the energy transfer between the two devices is determined on the basis of the information exchanged. 6. Device as claimed in any of the foregoing claims 1-5, with sensors which measure at which first coil an energy consumer is present, after which communication between energy consumer and central energy system is started, resulting in a decision whether or not to supply energy from the central energy system to the consumer. 7. Method for wirelessly transferring electrical energy to vehicles according to one of the preceding claims 1 to 6. 1 0 370 29