# US 10,483,870 B2 · Power conversion method using variable potential energy storage devices > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,483,870 B2 - Document ID: US10483870B2 - Status: Granted - Kind: B2 - Application number: 15/573,250 - Filed: 2016-05-12 - Published: 2018-05-10 - Granted: 2019-11-19 - Earliest claimed: 2015-05-13 - Assignees: Offshore Renewable Energy Catapult - Applicants: Offshore Renewable Energy Catapult - Inventors: Chong Hwa Ng; Paul McKeever; Michael Edward Smailes - Web page: https://patentgrep.com/patent/US10483870B2 ## CPC - H02M 7/4835: {comprising two or more cells, each including a switchable capacitor, the capacitors having a nominal charge voltage which corresponds to a given fraction of the input voltage, and the capacitors being selectively connected in series to determine the instantaneous output voltage} - H02M 7/49: Combination of the output voltage waveforms of a plurality of converters - H02M 7/501: sinusoidal output voltages being obtained by the combination of several pulse-voltages having different amplitude and width - Y02E 10/76: Power conversion electric or electronic aspects - H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P) - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION ## Abstract A power conversion method comprising: charging a plurality of energy storage devices of a power converter from an input power source; and sequentially coupling and decoupling energy storage devices of the plurality of energy storage devices to an output. Charging the plurality of energy storage devices comprises maintaining at least two of the plurality of energy storage devices at substantially different potentials. ## Claims ### Claim 1 A power conversion method, comprising: charging a plurality of energy storage devices of a power converter from an input power source, wherein the power converter comprises at least one branch including a first arm connected between an AC terminal and a first DC rail and a second arm connected between the AC terminal and a second DC rail; and sequentially coupling and decoupling energy storage devices of the plurality of energy storage devices to an output, wherein charging the plurality of energy storage devices comprises maintaining at least two of the plurality of energy storage devices at substantially different potentials, and wherein a plurality of energy storage devices in each arm are grouped into sets of at least two energy storage devices, and a control unit is arranged to control charging of the energy storage devices, within each set, to a substantially equal potential, and the energy storage devices in each set of an arm are charged to a significantly different potential from all other sets of said arm. ### Claim 2 (depends on 1) A method according to claim 1, wherein the input power source is a high voltage DC power source, and sequentially coupling and decoupling the energy storage devices of the plurality of energy storage devices to the output generates output voltage levels corresponding to an AC voltage waveform. ### Claim 3 (depends on 1) A method according to claim 1, wherein the input power source is a high voltage AC power source, and sequentially coupling and decoupling the energy storage devices of the plurality of energy storage devices to the output generates an output DC voltage waveform. ### Claim 4 (depends on 1) A method according to claim 1, wherein the steps of sequentially coupling and decoupling the energy storage devices of the plurality of energy storage devices and charging the plurality of energy storage devices are in accordance with a control algorithm. ### Claim 5 (depends on 1) A method according to claim 1, wherein one or more of the energy storage devices are sequentially coupled to the output such that the energy storage devices can be coupled in a forward polarity and a reverse polarity. ### Claim 6 (depends on 4) A method according to claim 4, wherein the control algorithm is arranged to change over time the potential to which individual energy storage devices are charged to. ### Claim 7 (depends on 1) A method according to claim 1, wherein the step of charging the plurality of energy storage devices is performed using pulse width modulation. ### Claim 8 (depends on 1) A method according to claim 1, comprising, selecting one or more sets from the plurality of sets, and selecting energy storage devices from the selected one or more sets to generate the output voltage levels. ### Claim 9 (depends on 1) A computer program stored on a non-transitory computer readable medium for controlling a power converter, said computer program when run on a processor being arranged to cause the processor to control the power converter to perform the power conversion method according to claim 1. ### Claim 10 A power converter comprising: at least one branch including a first arm connected between an AC terminal and a first DC rail and a second arm connected between the AC terminal and a second DC rail; and a plurality of energy storage devices and a control unit, said control unit arranged to control charging of the energy storage devices by an input power source, and said control unit is further arranged to control a sequential coupling and decoupling of the energy storage devices to an output of the converter, wherein charging the plurality of energy storage devices comprises maintaining at least two of the plurality of energy storage devices at substantially different potentials, and wherein a plurality of storage devices in each arm are grouped into sets of at least two energy storage devices, and the control unit is arranged to control charging of the energy storage devices, within each set, to a substantially equal potential, and the energy storage devices in each set of an arm are charged to a significantly different potential from all other sets of said arm. ### Claim 11 (depends on 10) A power converter according to claim 10, wherein the input power source is a high voltage DC power source, and the control unit controls the sequential coupling and decoupling of the energy storage devices to the output to generate output voltage levels corresponding to an AC voltage waveform. ### Claim 12 (depends on 10) A power converter according to claim 10, wherein the input power source is a high voltage AC power source, and the control unit controls the sequential coupling and decoupling of the energy storage devices to the output to generate output voltage levels corresponding to a DC voltage waveform. ### Claim 13 (depends on 10) A power converter according to claim 10, wherein the control unit controls the charging of the energy storage devices and controls the sequential coupling and decoupling of the energy storage devices to the output in accordance with a control algorithm. ### Claim 14 (depends on 10) A power converter according to claim 10, wherein one or more of the energy storage devices are arranged to be coupled to the output in a forward polarity and a reverse polarity to generate the output voltage levels. ### Claim 15 (depends on 13) A power converter according to claim 13, wherein the control algorithm is arranged to change over time the potential to which individual energy storage devices are charged to. ### Claim 16 (depends on 10) A power convertor according to claim 10, wherein the control unit is arranged to select one or more sets from the plurality of sets and then to select specific energy storage devices from the selected one or more sets to generate the output voltage levels. ### Claim 17 (depends on 16) A power converter according to claim 16, wherein the control unit comprises a high level power control function, a final stage module selector and a set control for selecting the sets, wherein the set control is positioned at a stage in the control unit between the high level power control function and the final stage module selector. ### Claim 18 (depends on 16) A power converter according to claim 16, wherein the control unit comprises a PWM control function and a final stage module selector and a set control for selecting the specific sets, wherein the set control is positioned at a stage in the control unit between the PWM control function and the final stage module selector.