The present invention relates to the transmission of power to a receiver to power a load, where the receiver preferably does not have a DC-DC converter. More specifically, the present invention relates to the transmission of power to a receiver to power a load, where the power is transmitted in pulses and where the receiver preferably does not have a DC-DC converter, or where the pulses of power are transmitted without any data, or where the receiver does not use the pulses as a clock to run a DC-DC converter.
Current methods of Radio Frequency (RF) power transmission use a Continuous Wave (CW) system. This means the transmitter continuously supplies a fixed amount of power to a remote unit (antenna, rectifier, device). However, the rectifier has an efficiency that is proportional to the power received by the antenna. To combat this problem, a new method of power transmission was developed that involves pulsing the transmitted power (On-Off Keying (OOK) the carrier frequency).
The present invention pertains to a transmitter for transmitting power to a receiver to power a load, where the receiver does not have a DC-DC converter. The transmitter comprises a pulse generator for producing pulses of power. The transmitter comprises an antenna in communication with the pulse generator through which the pulses are transmitted from the transmitter.
The present invention pertains to a system for power transmission. The system comprises a transmitter which transmits only pulses of power without any data. The system comprises a receiver which receives the pulses of power transmitted by the power transmitter to power a load.
The present invention pertains to a method for transmitting power to a receiver to power a load. The method comprises the steps of producing pulses of power with a pulse generator. There is the step of transmitting the pulses through an antenna in communication with the pulse generator to the receiver to power the load.
The present invention pertains to a method for transmitting power. The method comprises the steps of transmitting pulses of power with a transmitter. The method comprises the step of receiving the pulses of power transmitted by the power transmitter with a receiver to power a load. The receiver has a rectifier whose efficiency is increased as compared to a corresponding continuous wave power transmission system by receiving the pulses of power.
The present invention pertains to an apparatus for transmitting power to a receiver to power a load. The apparatus comprises a plurality of transmitters, each of which produce pulses of power which are received by the receiver to power the load.
The present invention pertains to a method for transmitting power to a receiver to power a load. The method comprises the steps of producing pulses of power from an apparatus having a plurality of transmitters which are received by the receiver to power the load.
The present invention pertains to a system for power transmission. The system comprises a transmitter which transmits pulses of power. The system comprises a receiver which receives the pulses of power transmitted by the power transmitter to power a load but does not use the pulses as a clock signal.
The present invention pertains to a system for power transmission. The system comprises means for transmitting pulses of power. The system comprises means for receiving the pulses of power transmitted by the transmitting means to power a load but does not use the pulses for a clock signal.
The present invention pertains to a transmitter for transmitting power to a receiver to power a load, where the receiver does not have a DC-DC converter. The transmitter comprises means for producing pulses of power. The transmitter comprises an antenna in communication with the pulse generator through which the pulses are transmitted from the transmitter.
In the accompanying drawings, the preferred embodiment of the invention and preferred methods of practicing the invention are illustrated in which:
a is a block diagram of a receiver.
a and 4b show multiple transmitters, single frequency, and multiple timeslots.
a and 6b show a single transmitter, single frequency and non-return to zero (NRZ).
a and 7b show a single transmitter, multiple frequencies and multiple timeslots.
a and 8b show multiple transmitters, single frequency and multiple timeslots.
a and 9b show single transmitter, multiple frequencies, multiple timeslots and NRZ.
a and 10b show single transmitter, multiple frequencies, multiple timeslots and return to zero (RZ).
a and 12b show multiple transmitters, multiple frequencies, multiple timeslots and varied amplitude.
Referring now to the drawings wherein like reference numerals refer to similar or identical parts throughout the several views, and more specifically to
Preferably, the pulse generator 14 includes a frequency generator 20 having an output, and an amplifier 22 in communication with the frequency generator 20 and the antenna 18.
The transmitter 12 preferably includes an enabler 24 which controls the frequency generator 20 or the amplifier 22 to form the pulses. Preferably, the enabler 24 defines a time duration between pulses as a function of a transmitting frequency of the pulses. The time duration is preferably greater than one-half of one cycle of the frequency generator 20 output. Preferably, the power of the transmitted pulses is equivalent to an average power of a continuous wave power transmission system 10. The average power Pavg of the pulses is preferably determined by
The pulses can be transmitted in any ISM band or in an FM radio band.
Alternatively, the pulse generator 14 produces a continuous amount of power between pulses, or the pulse generator 14 produces pulses at different output frequencies sequentially, as shown in
Alternatively, the pulse generator 14 transmits data between the pulses or the pulse generator 14 transmits data in the pulses, or both.
Alternatively, the transmitter 12 includes a gain control 26 which controls the frequency generator 20 or the amplifier 22 to form the pulses, as shown in
The present invention pertains to a system 10 for power transmission, as shown in
Preferably, the receiver 32 includes a rectifier 28. The rectifier 28 efficiency is preferably increased by over 5 percent as compared to a corresponding continuous wave power transmission system 10 by receiving the pulses of power. Preferably, the rectifier 28 efficiency is increased by over 100 percent as compared to a corresponding continuous wave power transmission system 10.
The present invention pertains to a method for transmitting power to a receiver 32 to power a load 16. The method comprises the steps of producing pulses of power with a pulse generator 14. There is the step of transmitting the pulses through an antenna 18 in communication with the pulse generator 14 to the receiver 32 to power the load 16.
The present invention pertains to a method for transmitting power. The method comprises the steps of transmitting pulses of power with a transmitter 12. The method comprises the step of receiving the pulses of power transmitted by the power transmitter 12 with a receiver 32 to power a load 16. The receiver 32 has a rectifier 28 whose efficiency is increased as compared to a corresponding continuous wave power transmission system 10 by receiving the pulses of power.
The present invention pertains to an apparatus for transmitting power to a receiver 32 to power a load 16. The apparatus comprises a plurality of transmitters 12, each of which produce pulses of power which are received by the receiver 32 to power the load 16, as shown in
Preferably, the apparatus includes a controller in communication with each transmitter 12. Each transmitter 12 is assigned an associated time slot by the controller so that only one pulse from the plurality of transmitters 12 is transmitted at a given time. The apparatus preferably includes a plurality of time slot selectors. Each transmitter 12 is in communication with a corresponding time slot selector of the plurality of time slot selectors. The controller issues a control signal to each selector which activates the corresponding transmitter 12 for its assigned time slot.
The present invention pertains to a method for transmitting power to a receiver 32 to power a load 16. The method comprises the steps of producing pulses of power from an apparatus having a plurality of transmitters 12 which are received by the receiver 32 to power the load 16.
The present invention pertains to a system 10 for power transmission. The system 10 comprises a transmitter 12 which transmits pulses of power. The system 10 comprises a receiver 32 which receives the pulses of power transmitted by the power transmitter 12 to power a load 16 but does not use the pulses as a clock 34 signal, as shown in
The present invention pertains to a system 10 for power transmission. The system 10 comprises means for transmitting pulses of power, such as shown in
The present invention pertains to a transmitter 12 for transmitting power to a receiver 32 to power a load 16, where the receiver 32 does not have a DC-DC converter 36. The transmitter 12 comprises means for producing pulses of power, such as shown in
Pulse Transmission Method (PTM)—1
In the operation of the invention, current methods of Radio Frequency (RF) power transmission use a Continuous Wave (CW) system. This means the transmitter 12 continuously supplies a fixed amount of power to a remote unit (antenna, rectifier, device). However, the rectifier 28 has an efficiency that is proportional to the power received by the antenna 18. To combat this problem, a new method of power transmission was developed that involves pulsing the transmitted power (On-Off Keying (OOK) the carrier frequency). Pulsing the transmission allows higher peak power levels to obtain an average value equivalent to a CW system. This concept is illustrated in
As shown in
The pulsing is accomplished by first enabling both the frequency generator 20 and the amplifier 22. Then the enable line, which will be enabled at this point, will be toggled on either the Frequency generator 20 or the Amplifier 22 to disable then re-enable one of the devices. This action will produce the pulsed output. As an example, if the enable line on the Frequency generator 20 is toggled ON and OFF, this would correspond to producing RF energy followed by no RF energy.
To distinguish the PTM from a CW system, it becomes necessary to define the minimum duration between pulses. This time will be a function of the transmitting frequency, and would be limited to one half of one cycle of the output from the frequency generator 20. It would be possible to decrease the OFF time further but switching during a positive or negative swing would produce harmonics that would be delivered to the antenna 18. This would mean frequencies other than the carrier would also be transmitted, leading to possible interference with other frequency bands. However, practically switching at such high rates will not be advantageous. The response times for the Frequency generator 20, Amp, and Rectifier 28 will almost always be longer than the short durations described. This means the system would not be able to respond to changes that quickly, and benefits of the PTM system would be degraded.
Examples of each block are as follows.
One example of where this method could be used is in the 890-940 MHz range. The Federal Communications Commission (FCC) lists requirements for operation in this band in Section 15.243 of the Code of Federal Regulations (CFR), Title 47. This specification appears in Appendix A. The regulations for this band specify that the emission limit is measured with an average detector, and peak transmissions are limited by Section 15.35, which appears in Appendix B. This regulation states that the peak emission is limited to 20 dB (100 times) the average power stated for that frequency band. This would correspond to a limit of X=100 in
It should be noted that this method works at any frequency. Tests have been performed in the FM radio band at 98 MHz. The tests were performed in a shielded room to avoid interference with radio service. The duty cycle of the pulse was varied from 100 percent (CW) to 1 percent with a constant period of 100 milliseconds (ms) and 1 second, which are shown in Table 2 and Table 3, respectively. The amplitude of the pulse was adjusted to obtain an average power of 1 milliwatt (mW). The tables show the various duty cycles tested, and the DC voltage and power converted by the receiver 32. The receiving circuit is illustrated in
Another example of frequency bands that may be useful when implementing this method includes the Industrial, Scientific, and Medical Band (ISM). This band was established to regulate industrial, scientific, and medical equipment that emits electromagnetic energy on frequencies within the radio frequency spectrum in order to prevent harmful interference to authorized radio communication services. These bands include the following: 6.78 MHz±15 KHz, 13.56 MHz±7 KHz, 27.12 MHz±163 KHz, 40.68 MHz±20 KHz, 915 MHz±13 MHz, 2450 MHz±50 MHz, 5800 MHz±75 MHz, 24125 MHz±125 MHz, 61.25 GHz±250 MHz, 122.5 GHz±500 MHz, and 245 GHz±1GHz.
The Pulsed Transmission System 10 has numerous advantages. Some of them are listed below.
There are current patents that bear a resemblance to the method described, however, their fundamental approach to the problem is for a different purpose. U.S. Pat. No. 6,664,770, incorporated by reference herein, describes a system that uses a pulse modulated carrier frequency to power a remote device that contains a DC to DC (DC-DC) converter. A DC-DC converter is used to transform the level of the input DC voltage up or down depending on the topology chosen. In this case, a boost converter is used to increase the input voltage. The device derives its power from the incoming field and also uses the modulation contained within the signal to switch a transistor (fundamental component in a DC-DC converter) for the purpose of increasing the received voltage. The waveform described within this document will have similar characteristics to the one described in the referenced patent. The system described here has numerous differences. The proposed receiver 32 does not contain a DC-DC converter. In fact, this method was developed for the purpose of increasing the received DC voltage without the need for a DC-DC converter. Also, the modulation contain within the proposed signal is not intended for use as a clock 34 to drive a switching transistor. Its purpose is to allow the use of a large peak power to increase the efficiency of the rectifying circuit, which in turn increases the receiver 32 output voltage without a need for a DC-DC converter or derivation of a clock 34 from the incoming pulsed signal.
As previously stated, the pulsed waveform is not intended for use as a clock 34 signal. If a DC-DC converter is needed in the receiving circuit because the pulsed waveform has not solely produced a large enough voltage increase (by the increase in efficiency), the DC-DC converter will be implemented using an on-board clock 34 generated using the pure DC output of the rectifier 28. The generation of the clock 34 in the receiver 32 proves to be more efficient than including extra circuitry to derive the clock 34 from the incoming pulsing waveform, hence providing a greater receiver 32 efficiency than the referenced patent.
There have recently been successful tests performed by Lucent Digital Radio, Inc., a venture of Lucent Technologies and Pequot Capital Management, Inc., to integrate digital radio service into the existing analog radio signals without interactions with the current service. With this being said, it is possible to integrate a power transmission signal, such as the one described in this document, into existing RF facilities (Radio, TV, Cellular, etc.) if it is found to be advantageous. This would allow the stations to provide content along with power to devices within a specified area.
Pulse Transmission Method—2
When multiple transmitters 12 are used, the pulse transmission method provides a solution to another common problem, phase cancellation. This is caused when two (or more) waves interact with one another. If one wave becomes 180 degrees out of phase with respect to the other, the opposite phases will cancel and little or no power will be available and that area will be a null. The pulse transmission method alleviates this problem due to its non-CW characteristics. This allows multiple transmitters 12 to be used at the same time without cancellation by assigning each transmitter 12 a timeslot so that only one pulse is active at a given time. For a low number of transmitters 12, timeslots may not be needed due to the low probability of pulse collisions. The system 10 hardware is shown in
Pulse Transmission Method—3
An extension on Method 2 eliminates the need for assigning timeslots. In this method, multiple channels (frequencies) are used to remove the interaction between transmitters 12. The use of multiple channels allows the transmitters 12 to operate concurrently while close channel spacing allows reception of all frequencies by the receiving antenna 18 and rectifier 28. This system 10 is shown in
Pulse Transmission Method—Alternatives
There are numerous extensions of the three methods previously described in this document. They include the following.
It should be noted that the pulse widths and periods of sequential pulses may vary with time. Also, the duration of each timeslot may be different and may vary with time.
Data could be included within the pulses for communications purposes. This would be accomplished by the inclusion of a data line(s) into the Frequency Generator(s) depicted in the previous figures. This line would be used to modulate the carrier frequency. The receiver 32 would contain an addition apparatus to extract the data from the incoming signal. This is shown in
Although the invention has been described in detail in the foregoing embodiments for the purpose of illustration, it is to be understood that such detail is solely for that purpose and that variations can be made therein by those skilled in the art without departing from the spirit and scope of the invention except as it may be described by the following claims.
Section
[Code of Federal Regulations]
[Title 47, Volume 1]
[Revised as of Oct. 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 47CFR15.243]
[Page 750]
Part 15—Radio Frequency Devices—Table of Contents
Sec. 15.243 Operation in the band 890-940 MHz.
(a) Operation under the provisions of this section is restricted to devices that use radio frequency energy to measure the characteristics of a material. Devices operated pursuant to the provisions of this section shall not be used for voice communications or the transmission of any other type of message.
(b) The field strength of any emissions radiated within the specified frequency band shall not exceed 500 microvolts/meter at 30 meters. The emission limit in this paragraph is based on measurement instrumentation employing an average detector. The provisions in Sec. 15.35 for limiting peak emissions apply.
(c) The field strength of emissions radiated on any frequency outside of the specified band shall not exceed the general radiated emission limits in Sec. 15.209.
(d) The device shall be self-contained with no external or readily accessible controls which may be adjusted to permit operation in a manner inconsistent with the provisions in this section. Any antenna that may be used with the device shall be permanently attached thereto and shall not be readily modifiable by the user.
[[Page 751]]
Section
[Code of Federal Regulations]
[Title 47, Volume 1]
[Revised as of Oct. 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 47CFR15.35]
[Page 701-702]
Part 15—Radio Frequency Devices—Table of Contents
Sec. 15.35 Measurement detector functions and bandwidths.
The conducted and radiated emission limits shown in this part are based on the following, unless otherwise specified elsewhere in this part:
(a) On any frequency or frequencies below or equal to 1000 MHz, the limits shown are based on measuring equipment employing a CISPR quasi-peak detector function and related measurement bandwidths, unless otherwise specified. The specifications for the measuring instrument using the CISPR quasi-peak detector can be found in Publication 16 of the International Special Committee on Radio Interference (CISPR) of the International Electrotechnical Commission. As an alternative to CISPR quasi-peak measurements, the responsible party, at its option, may demonstrate compliance with the emission limits using measuring equipment employing a peak detector function, properly adjusted for such factors as pulse desensitization,
[[Page 702]]
as long as the same bandwidths as indicated for CISPR quasi-peak measurements are employed.
Note: For pulse modulated devices with a pulse-repetition frequency of 20 Hz or less and for which CISPR quasi-peak measurements are specified, compliance with the regulations shall be demonstrated using measuring equipment employing a peak detector function, properly adjusted for such factors as pulse desensitization, using the same measurement bandwidths that are indicated for CISPR quasi-peak measurements.
(b) Unless otherwise stated, on any frequency or frequencies above 1000 MHz the radiated limits shown are based upon the use of measurement instrumentation employing an average detector function. When average radiated emission measurements are specified in this part, including emission measurements below 1000 MHz, there also is a limit on the radio frequency emissions, as measured using instrumentation with a peak detector function, corresponding to 20 dB above the maximum permitted average limit for the frequency being investigated unless a different peak emission limit is otherwise specified in the rules, e.g., see Secs. 15.255, 15.509 and 15.511. Unless otherwise specified, measurements above 1000 MHz shall be performed using a minimum resolution bandwidth of 1 MHz. Measurements of AC power line conducted emissions are performed using a CISPR quasi-peak detector, even for devices for which average radiated emission measurements are specified.
(c) Unless otherwise specified, e.g. Sec. 15.255(b), when the radiated emission limits are expressed in terms of the average value of the emission, and pulsed operation is employed, the measurement field strength shall be determined by averaging over one complete pulse train, including blanking intervals, as long as the pulse train does not exceed 0.1 seconds. As an alternative (provided the transmitter operates for longer than 0.1 seconds) or in cases where the pulse train exceeds 0.1 seconds, the measured field strength shall be determined from the average absolute voltage during a 0.1 second interval during which the field strength is at its maximum value. The exact method of calculating the average field strength shall be submitted with any application for certification or shall be retained in the measurement data file for equipment subject to notification or verification.
[54 FR 17714, Apr. 25, 1989, as amended at 56 FR 13083, Mar. 29, 1991; 61 FR 14502, Apr. 2, 1996; 63 FR 42279, Aug. 7, 1998; 67 FR 34855, May 16, 2002]
Number | Date | Country | |
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60656165 | Feb 2005 | US |