This invention relates to an inductive power transmitter. The power transmitter is able to regulate, at least to some degree, the power provided to its transmitter coil without requiring information as to operating parameters on the receiver side.
Inductive power transfer (IPT) technology is an area of increasing development and IPT systems are now utilised in a range of applications and with various configurations. Typically, a primary side (i.e., an inductive power transmitter) will include a transmitting coil or coils configured to generate an alternating magnetic field. This magnetic field induces an alternating current in the receiving coil or coils of a secondary side (i.e., an inductive power receiver). This induced current in the receiver can then be provided to some load, for example, for charging a battery or powering a portable device. In some instances, the transmitting coil(s) or the receiving coil(s) may be suitably connected with capacitors to create a resonant circuit. This can increase power throughput and efficiency at the corresponding resonant frequency.
A problem associated with IPT systems is regulating the amount of power provided to the load. It is important to regulate the power provided to the load to ensure the power is sufficient to meet the load's power demands. Similarly, it is important that the power provided to the load is not excessive, which may lead to inefficiencies. Generally, there are two approaches to power control in IPT systems: transmitter-side power control and receiver-side power control.
In transmitter-side power control, the transmitter is typically controlled to adjust the power of the generated magnetic field (for example, by adjusting the power supplied to the transmitting coil(s)).
In receiver-side power control, the receiver is controlled to adjust the power provided to the load from the receiving coils (for example, by including a regulating stage or by adjusting the tuning of the receiver).
A problem associated with some transmitter-side power control systems is that they require measurement of receiver-side operational parameters and communication of these to the transmitter, increasing complexity and cost of both the transmitter and receiver.
One known approach is to rely upon primary side real and imaginary components of the tank capacitor voltage to infer receiver output voltage and coil coupling. Without accurate measurement of these parameters the controller cannot accurately control power. It can be difficult and expensive to obtain useful phase measurements, especially at light loads where the resonant waveforms may become non-sinusoidal. Phase information may also be influenced by many variables in the system making it difficult to isolate phase components. Filtering may be employed, however this will add complexity and delay. In summary, it can be difficult and expensive to produce a cost effective and responsive solution suitable for real world applications using this approach.
Further in the above approach primary side only control (i.e. no power flow control is provided on the secondary side) is employed. Whilst this may be suitable for stable loads without sudden changes in the load requirements it is not suitable for applications where there may be sudden changes in load requirements and may result in instability.
Accordingly, the object of the present invention is to provide an improved IPT transmitter or to at least provide the public with a useful choice.
According to one exemplary embodiment there is provided an IPT power transmitter including:
According to another aspect there is provided an IPT power transmitter including:
According to a further aspect there is provided an IPT power transmitter including:
It is acknowledged that the terms “comprise”, “comprises” and “comprising” may, under varying jurisdictions, be attributed with either an exclusive or an inclusive meaning. For the purpose of this specification, and unless otherwise noted, these terms are intended to have an inclusive meaning—i.e., they will be taken to mean an inclusion of the listed components which the use directly references, and possibly also of other non-specified components or elements.
Reference to any document in this specification does not constitute an admission that the document is prior art, that it is validly combinable with other documents or that it forms part of the common general knowledge.
The accompanying drawings which are incorporated in and constitute part of the specification, illustrate embodiments of the invention and, together with the general description of the invention given above, and the detailed description of embodiments given below, serve to explain the principles of the invention.
The transmitter circuit 1 includes an H bridge formed of switches 3 to 6 which alternately switch in pairs (switches 3 and 6 on and 4 and 5 off; then 4 and 5 on and 3 and 6 off) under the control of control circuit 2 (drive lines not shown for simplicity of representation) to alternately supply a voltage of alternating polarity from DC supply 7 to a resonant circuit 8. In this example the resonant circuit includes transmitter coil 9, tank capacitor 10, tuning capacitor 11 and tuning inductor 12. However, it is to be appreciated that LCL, LCCL, CLCCL or other suitable resonant circuit topologies may be used. The bridge is switched at high frequency (typically around 200 kHz) with the duty cycle adjusted by control circuit 2 to maintain a desired voltage across the transmitter coil 9. Voltage sensor 13 monitors the voltage across the transmitter coil and supplies this to control circuit 2. Current sensor 14 monitors the current flowing through tuning inductor 12 and supplies this to control circuit 2. Current sensor 15 monitors the current supplied by DC power supply 7 and supplies this to control circuit 2. Voltage sensor 16 monitors the output voltage of DC power supply 7 and supplies this to control circuit 2. The connections from the voltage and current sensors to control circuit 2 are also omitted for simplicity of representation.
Referring now to
As will be seen in
The ratio of the current IAC to IDC provides a good proxy for coil coupling. As coupling increases (i.e. the transmitter and receiver coils are closer together) the required voltage across the transmitter coil VAC decreases and so the ratio of the current IAC to IDC determined and scaled at 17 and is subtracted from the target voltage VAC target by summer 18 to compensate for changes in coil coupling. This is the primary feedback component used to adjust VAC target.
It may also be desirable to include a feedback component based on the level of power supplied by the power supply. This component provides compensation when the power supplied by the power supply 7 is high to further reduce VAC target. This improves efficiency during light load operation to scale the transmitter power output to better match the receiver power requirements. The product VDC*IDC is determined and scaled at 19 and subtracted at summer 20.
Summer 21 subtracts the output of summer 20 from VAC as measured by circuit 1 to produce an error signal as stated below:
Error=VAC target−K1*(IAC/IDC)−K2*(VDC/IDC)−VAC
This error signal is utilised to control the switching duty cycle of the H bridge to maintain the required transmitter coil voltage. The terms K1*(IAC/IDC) and K2*(VDC*IDC) will provide little or no feedback at maximum transmitter and receiver coil separation and will increasingly provide negative feedback as the coils come closer together.
Operation of the controller may be further enhanced by further conditioning of the error signal. In a first stage the error signal may be rate limited. In
The error signal may be further conditioned by scaling the duty cycle at 23 based on the output voltage VDC of the DC supply 7. This directly compensates for changes in the output voltage VDC of the DC supply 7 by adjusting the duty cycle in dependence upon VDC. The output signal of component 23 is supplied to circuit 1 to set the duty cycle for switching of the H bridge.
It will be appreciated that both of the above embodiments could be combined to effect control based both on transmitter coil voltage and transmitter coil current. This embodiment would provide control based on power rather than just voltage or current. This would provide the reactive power of the primary tank, and so would provide the most accurate control, although it would require two transmitter coil sensors as opposed to one.
Instead of increasing the duty cycle to increase power and reducing it to decrease power, the output voltage of the DC/DC converter may be adjusted to do this (i.e. increase the output voltage of DC/DC converter 27 to increase power and decrease the output voltage of DC/DC converter 27 to decrease power.
It will be appreciated that both duty cycle control and DC/DC converter output voltage control may be employed together. This provides greater flexibility to decrease or increase power through the use of both mechanisms. In this embodiment the IPT transmitter may be controlled to work at much higher and lower coupling coefficient values which may enable the minimum spacing between transmitter and receiver coils to be reduced (decreased Z-distance).
For example, where an IPT system is designed to operate over a large range of coil separation distances (large Z-distance range) and operate at a close coil separation (small Z-distance) duty cycle control alone may not be sufficient at close coil separation to handle the current through the tuning coil unless a very large tuning inductor is used. However, by controlling the output voltage of the DC/DC converter as well as the duty cycle, this problem can be overcome and a greater range of coil separation may be accommodated.
The above embodiments have been found to provide effective control over a wide range of transmitter and receiver coil spacings and power requirements whilst being a relatively simple, compact and inexpensive design. The approach is not dependent upon the receiver topology employed and so may be used in a wide range of applications.
While the present invention has been illustrated by the description of the embodiments thereof, and while the embodiments have been described in detail, it is not the intention of the Applicant to restrict or in any way limit the scope of the appended claims to such detail. For example it will be appreciated that the embodiment disclosed may be adapted for use with an AC power supply. Additional advantages and modifications will readily appear to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details, representative apparatus and method, and illustrative examples shown and described. Accordingly, departures may be made from such details without departure from the spirit or scope of the Applicant's general inventive concept.
Number | Name | Date | Kind |
---|---|---|---|
3898549 | Mitchell | Aug 1975 | A |
4729088 | Wong | Mar 1988 | A |
4797541 | Billings et al. | Jan 1989 | A |
4959765 | Weinburg | Sep 1990 | A |
5293308 | Boys et al. | Mar 1994 | A |
5304917 | Somerville | Apr 1994 | A |
5386359 | Nochi | Jan 1995 | A |
5428521 | Kigawa et al. | Jun 1995 | A |
5510974 | Gu et al. | Apr 1996 | A |
5570278 | Cross | Oct 1996 | A |
5654881 | Albrecht et al. | Aug 1997 | A |
5751560 | Yokoyama | May 1998 | A |
5898579 | Boys et al. | Apr 1999 | A |
5923308 | Wei et al. | Jul 1999 | A |
6021052 | Unger et al. | Feb 2000 | A |
6069801 | Hodge, Jr. et al. | May 2000 | A |
6069803 | Cross | May 2000 | A |
6141225 | Gak et al. | Oct 2000 | A |
6191957 | Peterson | Feb 2001 | B1 |
6249444 | Cross | Jun 2001 | B1 |
6473318 | Qian et al. | Oct 2002 | B1 |
6587356 | Zhu et al. | Jul 2003 | B2 |
6728118 | Chen et al. | Apr 2004 | B1 |
6803744 | Sabo | Dec 2004 | B1 |
7180759 | Liptak et al. | Feb 2007 | B2 |
7279850 | Boys et al. | Oct 2007 | B2 |
7521890 | Lee et al. | Apr 2009 | B2 |
7548436 | Chen | Jun 2009 | B1 |
7606051 | Wittenbreder, Jr. | Oct 2009 | B1 |
7639514 | Baarman | Dec 2009 | B2 |
7640757 | Lee | Jan 2010 | B2 |
7764515 | Jansen et al. | Jul 2010 | B2 |
7948208 | Partovi et al. | May 2011 | B2 |
8169185 | Partovi et al. | May 2012 | B2 |
8314513 | Aoyama et al. | Nov 2012 | B2 |
8417359 | Tsai et al. | Apr 2013 | B2 |
8446251 | Kozuma et al. | May 2013 | B2 |
8587154 | Fells et al. | Nov 2013 | B2 |
8629654 | Partovi et al. | Jan 2014 | B2 |
8855554 | Cook et al. | Oct 2014 | B2 |
8884469 | Lemmens et al. | Nov 2014 | B2 |
8912730 | Nakajo et al. | Dec 2014 | B2 |
8923015 | Madawala et al. | Dec 2014 | B2 |
9168083 | Schall et al. | Oct 2015 | B2 |
20060226816 | Wai et al. | Oct 2006 | A1 |
20060291117 | Kyono | Dec 2006 | A1 |
20080013344 | Mori | Jan 2008 | A1 |
20080211478 | Hussman et al. | Sep 2008 | A1 |
20090003862 | Tominaga | Jan 2009 | A1 |
20090096413 | Partovi et al. | Apr 2009 | A1 |
20090230777 | Baarman et al. | Sep 2009 | A1 |
20090268489 | Lin et al. | Oct 2009 | A1 |
20100067259 | Liu | Mar 2010 | A1 |
20100181961 | Von Novak et al. | Jul 2010 | A1 |
20100202176 | Hallak | Aug 2010 | A1 |
20100259217 | Baarman et al. | Oct 2010 | A1 |
20100327661 | Karalis et al. | Dec 2010 | A1 |
20110006743 | Fabbro | Jan 2011 | A1 |
20110046438 | Iwaisako | Feb 2011 | A1 |
20110221277 | Boys | Sep 2011 | A1 |
20110254379 | Madawala | Oct 2011 | A1 |
20110260681 | Guccione et al. | Oct 2011 | A1 |
20120002446 | Madawala et al. | Jan 2012 | A1 |
20120011958 | Kihara | Jan 2012 | A1 |
20120068550 | Boer et al. | Mar 2012 | A1 |
20120161535 | Jung et al. | Jun 2012 | A1 |
20120242163 | Jung et al. | Sep 2012 | A1 |
20120313577 | Moes et al. | Dec 2012 | A1 |
20130033118 | Karalis et al. | Feb 2013 | A1 |
20130043951 | Irish et al. | Feb 2013 | A1 |
20130147427 | Polu et al. | Jun 2013 | A1 |
20130154373 | Lisuwandi et al. | Jun 2013 | A1 |
20130234531 | Budgett et al. | Sep 2013 | A1 |
20130300209 | Long et al. | Nov 2013 | A1 |
20130307348 | Oettinger et al. | Nov 2013 | A1 |
20140015333 | Byun et al. | Jan 2014 | A1 |
20140132210 | Partovi | May 2014 | A1 |
20140159500 | Sankar et al. | Jun 2014 | A1 |
20140252874 | Niizuma | Sep 2014 | A1 |
20140293670 | Robertson et al. | Oct 2014 | A1 |
20140333150 | Iwawaki | Nov 2014 | A1 |
20150015197 | Mi et al. | Jan 2015 | A1 |
20150054354 | Lemmens et al. | Feb 2015 | A1 |
20150280455 | Bosshard et al. | Oct 2015 | A1 |
20160111895 | Bae | Apr 2016 | A1 |
20170207724 | Robertson et al. | Jul 2017 | A1 |
20170346339 | Dela Cruz | Nov 2017 | A1 |
20180097406 | Chen | Apr 2018 | A1 |
Number | Date | Country |
---|---|---|
101728965 | Jun 2010 | CN |
103795261 | May 2014 | CN |
104079079 | Oct 2014 | CN |
2286727 | Feb 2011 | EP |
2405553 | Jan 2012 | EP |
2642628 | Sep 2013 | EP |
2001297862 | Oct 2001 | JP |
2003219659 | Jul 2003 | JP |
2006149168 | Jun 2006 | JP |
2006529079 | Dec 2006 | JP |
2010200497 | Sep 2010 | JP |
573241 | Apr 2011 | NZ |
9323908 | Nov 1993 | WO |
9908359 | Feb 1999 | WO |
2003105308 | Dec 2003 | WO |
2004042750 | May 2004 | WO |
2004105208 | Dec 2004 | WO |
2004105226 | Dec 2004 | WO |
2007031914 | Mar 2007 | WO |
2007100265 | Sep 2007 | WO |
2009012778 | Jan 2009 | WO |
2009037613 | Mar 2009 | WO |
2009061219 | May 2009 | WO |
2009081115 | Jul 2009 | WO |
2010000010 | Jan 2010 | WO |
2010030195 | Mar 2010 | WO |
2010062201 | Jun 2010 | WO |
2010115976 | Oct 2010 | WO |
2011046453 | Apr 2011 | WO |
2011099071 | Aug 2011 | WO |
2012005607 | Jan 2012 | WO |
2012030238 | Mar 2012 | WO |
2012035745 | Mar 2012 | WO |
2012125590 | Sep 2012 | WO |
2013002651 | Jan 2013 | WO |
2013020138 | Feb 2013 | WO |
2013112614 | Aug 2013 | WO |
2013164831 | Nov 2013 | WO |
2014042681 | Mar 2014 | WO |
2014057959 | Apr 2014 | WO |
2014070025 | May 2014 | WO |
2014091250 | Jun 2014 | WO |
2014070025 | Oct 2014 | WO |
2014201461 | Dec 2014 | WO |
2015123651 | Aug 2015 | WO |
2016001873 | Jan 2016 | WO |
2016099295 | Jun 2016 | WO |
Entry |
---|
Chongwen Zhao et al. “Active Resonance Wireless Power Transfer System Using Phase Shift Control Strategy,” IEEE Applied Power Electronics Conference and Exposition, Apr. 24, 2014, p. 1336-1341, College of Electrical Engineering, Hangzhou, China. |
Bascope et al. “Isolated Flyback-Current-Fed Push-Pull Converter for Power Factor Correction.” IEEE. 1996. pp. 1184-1190. |
Bell. “Introduction to Push-Pull and Cascaded Power Converter Topologies.” Power Point Presentation for National Semiconductor Phoenix Arizona Design Center. 2003. (22 pages). |
Ben-Yaakov et al. “A Self-Adjusting Sinusoidal Power Source Suitable for Driving Capacitive Loads.” IEEE. 2004. (4 pages). |
Ben-Yaakov et al. “Modeling and Behavioral SPICE Simulation of a Self Adjusting Current-Fed Push-Pull Parallel Resonant Inverter (SA-CFPPRI)” IEEE. 2004. pp. 61-67. |
Chen et al. “A Novel Single Stage Push Pull Converter with Integrated Magnetics and Ripple-free Input Current.” |
Madawala et al. “Mathematical model for split-capacitor push-pull parallel resonant converter in Buck mode.” IET Power Electron. vol. 1. No. 3. 2008. pp. 356-367. |
Madawala et al. “Operation of a Split-Capacitor Push-Pull Parallel Resonant Converter in Buck Mode.” IEEE. 2007. pp. 1586-1591. |
Peretz et al. “The self-adjusting current-fed push-pull parallel resonant inverter as a high frequency AC bus driver.” IIAIT J. of Sci & Engineering. vol. 2. I. 3-4. 2005. pp. 352-364. |
Peretz et al. “The Self-Adjusting Current-Fed Push-Pull Parallel Resonant Inverter as high frequency AC bus driver.” IEEE. 2004. pp. 52-55. |
Thrimawithana et al. “A novel buck-boost control technique for push-pull parallel-resonant converters.” IEEE. 2006. pp. 2805-2810. |
Thrimawithana et al. “Analysis of Split-Capacitor Push-Pull Parallel Resonant Converter in Normal Mode.” SPEEDAM IEEE. 2008. pp. 778-783. |
Thrimawithana et al. “Analysis of Split-Capacitor Push-Pull Parallel Resonant Converter in Boost Mode.” IEEE. vol. 23. No. 1. 2008. pp. 359-368. |
Wu, T. et al., “Soft-Switching Bidirectional Isolated Full-Bridge Converter with Active and Passive Snubbers”, IEEE Transactions on Industrial Electronics, Mar. 2014, vol. 61, No. 3, pp. 1368-1376. |
Weerasinghe. “A novel resonant converter for low to medium power IPT applications”, published Dec. 6, 2014. |
Unknown. “Design of a 100 W Active Clamp Forward DC-DC Converter for Telecom Systems Using the NCP1562”, http://onsemi.com, May 2013. |
King et al., “Incorporating Active-Clamp Technology to Maximize Efficiency in Flyback and Forward Designs”, 2010 Texas Instruments Power Supply Design Seminar. |
Zhao, T. et al., “Optimal Operation Point Tracking Control for Inductive Power Transfer System” 2015 IEEE Wireless PowerTransfer Conference (WPTC) May 13-15, 2015. |
Rashid, M.H. et al., “Power Electronics Handbook: Devices, Circuits, and Applications” Third Edition, published by Elsevier Inc., 2001. |
Ren, U.S. Appl. No. 15/537,139, filed Jun. 16, 2017. |
D.J. Thrimawithana et al., Analysis of Split-Capacitor Push-Pull Parallel Resonant Converter in Normal Mode, International Symposium on Power Electronics, 2008, p. 778-783, Electrical Drives, Automation and Motion Department of Electrical & Computer Engineering, The University of Auckland, Auckland, New Zealand. |
Number | Date | Country | |
---|---|---|---|
20180351409 A1 | Dec 2018 | US |
Number | Date | Country | |
---|---|---|---|
62383787 | Sep 2016 | US |
Number | Date | Country | |
---|---|---|---|
Parent | PCT/NZ2017/050113 | Aug 2017 | US |
Child | 16041553 | US |