Multilevel converter

Patent metadata

Field	Value
Publication number	US-11223233-B2
Application number	US-201515120385-A
Country	US
Kind code	B2
Filing date	Feb 23, 2015
Priority date	Feb 21, 2014
Publication date	Jan 11, 2022
Grant date	Jan 11, 2022

Abstract

An inductive power transfer (IPT) converter has a first switching means adapted to produce a time varying input power signal comprising a substantially unipolar stepped waveform, and a second switching means adapted to modify the time varying input power signal provided by the first switching means to produce a modified input power signal. The converter is coupled to a resonant circuit to receive the modified input signal.

First claim

The invention claimed is:

1. A device, comprising:
a resonant circuit with at least one coil that is configured to transfer power inductively;
a first switching stage that connects the resonant circuit to a plurality of DC sources; and
a second switching stage that includes an H bridge inverter that connects the first switching stage to the resonant circuit;
wherein the first switching stage switches at a switching frequency that is a multiple of the resonant frequency of the resonant circuit,
wherein the first switching stage includes at least:
a first portion that includes a first voltage source of the plurality of DC sources and two first switches configured to switch the first voltage source into and out of the resonant circuit; and
a second portion that includes a second voltage source of the plurality of DC sources and two second switches configured to switch the second voltage source into or out of the resonant circuit,
wherein a third voltage source of the plurality of DC sources is directly connected to the first portion and/or the second portion, and

wherein the first switching stage is configured so that minimum voltage supplied to the second switching stage when the device is operating is non-zero.

2. The device of claim 1 , wherein the resonant circuit comprises a compensation circuit, and the compensation circuit is configured to tune the at least one coil to a frequency in the range of 60-100 kHz.

3. The device of claim 1 , wherein the resonant circuit comprises a compensation circuit, the compensation circuit comprises at least one capacitor, and the at least one capacitor is arranged in parallel with the at least one coil to form the resonant circuit.

4. The device of claim 1 , wherein the resonant circuit comprises a compensation circuit, and the compensation circuit comprises an LC circuit.

5. The device of claim 1 , wherein the second switching stage is configured to be soft switched.

6. The device of claim 1 , wherein the second switching stage comprises IGBT switches, and the second switching stage is configured to operate the H bridge inverter at a switching frequency greater than 40 kHz.

7. A method comprising coupling current from a plurality of DC sources to a resonant circuit via two switching stages, wherein a first of the two switching stages is switched, with a frequency that corresponds to a multiple of the resonant frequency of the resonant circuit, to couple current from the DC sources to the second of the two switching stages, and the second of the two switching stages includes an H bridge inverter and is switched to couple current from the first switching stage to the resonant circuit for inductive power transfer,
wherein the first switching stage includes at least:
a first portion that includes a first voltage source of the plurality of DC sources and two first switches configured to switch the first voltage source into and out of the resonant circuit; and
a second portion that includes a second voltage source of the plurality of DC sources and two second switches configured to switch the second voltage source into or out of the resonant circuit,
wherein a third voltage source of the plurality of DC sources is directly connected to the first portion and/or the second portion, and
wherein the first switching stage is configured so that minimum voltage supplied to the second switching stage when the device is operating is non-zero.

8. The method of claim 7 , wherein the method comprises switching the inverter with a switching frequency in the range of 60-100 kHz.

9. The method of claim 7 , wherein the method comprises operating the first of the two switching stages, using selective harmonic elimination, to selectively attenuate at least one voltage harmonic.

10. The method of claim 7 , wherein the method comprises operating the first of the two switching stages to selectively attenuate the third and/or ninth voltage harmonics.

11. A device comprising:
a resonant circuit with at least one coil that is configured to transfer power inductively;
a level stage that connects the resonant circuit to a plurality of DC sources; and
an inverter stage that includes an H bridge inverter that connects the level stage to the resonant circuit,
wherein the device is configured to switch the level stage to produce a signal, for the inverter stage, that has a dominant harmonic that is double the resonant frequency of the resonant circuit, and
wherein the level stage includes at least:
a first portion that includes a first voltage source of the plurality of DC sources and two first switches configured to switch the first voltage source into and out of the resonant circuit; and
a second portion that includes a second voltage source and two second switches configured to switch the second voltage source of the plurality of DC sources into or out of the resonant circuit,
wherein a third voltage source of the plurality of DC sources is directly connected to the first portion and/or the second portion, and
wherein the level stage is configured so that minimum voltage supplied to the inverter stage when the device is operating is non-zero.

12. The device of claim 11 , wherein the resonant circuit comprises a compensation circuit, and the compensation circuit is configured to tune the at least one coil to a frequency in the range of 70-85 kHz.

13. The device of claim 11 , wherein the resonant circuit comprises a compensation circuit, the compensation circuit comprises at least one capacitor, and the at least one capacitor is arranged in parallel with the at least one coil to form the resonant circuit.

14. The device of claim 11 , wherein the resonant circuit comprises a compensation circuit, and the compensation circuit comprises an LC circuit.

15. The device of claim 11 , wherein the inverter stage is configured to be soft switched.

16. A method comprising transferring power wirelessly from a resonant inductive power transfer primary, at the resonant frequency of the resonant inductive power transfer primary, wherein the method comprises generating a time-varying unipolar waveform, with a frequency that corresponds to a multiple of the resonant frequency of the resonant inductive power transfer primary, and generating a time-varying bipolar waveform, from the time-varying unipolar waveform, with a frequency that corresponds to the resonant frequency of the resonant inductive power transfer primary,
wherein the method further comprises sourcing current from a plurality of DC power sources and switching the plurality of DC power sources at different frequencies to generate the unipolar waveform,
wherein switching the plurality of DC sources at different frequencies is executed via a first switching stage and a second switching stage, the second switching stage including an H bridge inverter,
wherein the first switching stage includes at least:

a first portion that includes a first voltage source of the plurality of DC sources and two first switches configured to switch the first voltage source into and out of a resonant circuit of the resonant inductive power transfer primary; and
a second portion that includes a second voltage source of the plurality of DC sources and two second switches configured to switch the second voltage source into or out of the resonant circuit,
wherein a third voltage source of the plurality of DC sources is directly connected to the first portion and/or the second portion and,
wherein the first switching stage is configured so that minimum voltage supplied to the second switching stage when the resonant ind

Assignees

• Madawala Udaya Kumara
• Thirmawithana Duleep Jayanath
• Rahnamaee Hamid Reza
• Auckland Uniservices Ltd

Inventors

• Madawala Udaya Kumara
• Thirmawithana Duleep Jayanath
• Rahnamaee Hamid Reza

Classifications

• H02J7/94

  in response to battery current · CPC title

• H02M7/483

  Converters with outputs that each can have more than two voltages levels · CPC title

• H02M1/0095

  Hybrid converter topologies, e.g. NPC mixed with flying capacitor, thyristor converter mixed with MMC or charge pump mixed with buck · CPC title

• H02M7/4815

  Resonant converters (H02M7/4811 and H02M7/4826 take precedence) · CPC title

• Y02T10/70

  Energy storage systems for electromobility, e.g. batteries · CPC title