# US 2018/0026463 A1 · Apparatus and method to apply voltage to fuel cell stack from high voltage system for usage during diagnostic tests > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0026463 A1 - Document ID: US20180026463A1 - Status: Published application - Kind: A1 - Application number: 15/216,149 - Filed: 2016-07-21 - Published: 2018-01-25 - Earliest claimed: 2016-07-21 - Assignees: GM Global Technology Operations LLC - Applicants: GM Global Technology Operations LLC - Inventors: JOSEPH BERG; KENNETH L. KAYE - Web page: https://patentgrep.com/patent/US20180026463A1 ## CPC - H02J 7/00: Circuit arrangements for charging or discharging batteries or for supplying loads from batteries - H01M 8/04082: Arrangements for control of reactant parameters, e.g. pressure or concentration - H01M 8/04873: {of the individual fuel cell} - H01M 8/0488: {of fuel cell stacks} - H01M 8/04888: {of auxiliary devices, e.g. batteries, capacitors} - H01M 8/04992: characterised by the implementation of mathematical or computational algorithms, e.g. feedback control loops, fuzzy logic, neural networks or artificial intelligence - H02M 3/156: with automatic control of output voltage or current, e.g. switching regulators - H02M 3/158: including plural semiconductor devices as final control devices for a single load - H01M 2250/20: Fuel cells in motive systems, e.g. vehicle, ship, plane - H02J 2101/30: Fuel cells - H02J 2207/20: Charging or discharging characterised by the power electronics converter - Y02E 60/50: Fuel cells - Y02T 90/40: Application of hydrogen technology to transportation, e.g. using fuel cells - H02J: ELECTRIC POWER NETWORKS; CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY - H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY - 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 - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract A fuel cell charging system includes a fuel cell stack having a first operating direct current (DC) voltage between fuel check stack terminals, a high voltage system operating at a first DC operating voltage different than and generally higher than the first operating voltage of the fuel cell stack, a boost converter in electrical connection with the fuel cell stack and the high voltage system, and a stack charging component that applies a second DC operating voltage, generally of lower value than that of the first normal operating voltage, to the fuel cell stack. The boost converter transfer electrical power from the fuel cell stack to the high voltage system during fuel cell operation. Characteristically, the second DC operating voltage applied to the fuel cell stack terminals is typically lower in value than that of the first DC operating voltage of both the fuel cell stack and the HV electrical system and is stepped down from the first DC operating voltage of the HV electrical system. ## Claims ### Claim 1 A fuel cell charging system comprising: a fuel cell stack having a fuel cell stack voltage between fuel check stack terminals, the fuel cell stack voltage being at a first voltage during normal fuel cell operation; a high voltage electrical system operating at a first DC operating voltage, the first DC operating voltage being higher than the first voltage of the fuel cell stack; a boost converter in electrical connection with the fuel cell stack and the high voltage electrical system, the boost converter transferring electrical power from the fuel cell stack to the high voltage electrical system during fuel cell operation; a step down voltage component that applies a second DC operating voltage to the fuel cell stack, the second DC operating voltage being stepped down from the first DC operating voltage of the high voltage electrical system to a charging voltage that is lower than the first voltage of the fuel cell stack during normal operation; and a FCS controller that is operable to send control signals to the boost converter and the step down voltage component. ### Claim 2 (depends on 1) The fuel cell charging system of claim 1 wherein the FCS controller is operable to disable the boost converter when the second DC operating voltage is applied to the fuel cell stack. ### Claim 3 (depends on 1) The fuel cell charging system of claim 1 further comprising a stack discharge circuit that when enabled reduces the voltage of the fuel cell stack through resistive energy discharge ### Claim 4 (depends on 3) The fuel cell charging system of claim 3 wherein the FCS controller determines if the fuel cell stack voltage is within predetermined voltage window having an upper voltage limit and a lower voltage limit. ### Claim 5 (depends on 4) The fuel cell charging system of claim 4 wherein the FCS controller is operable to send a control signal to enable the stack discharge circuit when the fuel cell stack voltage is above the upper voltage limit. ### Claim 6 (depends on 5) The fuel cell charging system of claim 5 wherein the FCS controller is operable to send a control signal to disable the stack discharge circuit when the fuel cell stack voltage is below the upper voltage limit. ### Claim 7 (depends on 4) The fuel cell charging system of claim 4 wherein the upper voltage limit is from 25 to 50 volts and the lower voltage limit is from 15 to 25 volts. ### Claim 8 (depends on 4) The fuel cell charging system of claim 4 wherein the predetermined voltage window is from 10 to 30 volts. ### Claim 9 (depends on 4) The fuel cell charging system of claim 4 wherein the FCS controller is operable to perform diagnostic test when the fuel cell stack voltage is within the predetermined voltage window. ### Claim 10 A fuel cell charging system comprising: a fuel cell stack having a fuel cell stack voltage between fuel cell stack terminals, the fuel cell stack voltage being at a first voltage during normal fuel cell operation; a high voltage electrical system operating at a first DC operating voltage, the first DC operating voltage being higher than the first voltage of the fuel cell stack; a boost converter in electrical connection with the fuel cell stack and the high voltage electrical system, the boost converter transferring electrical power from the fuel cell stack to the high electrical voltage system during fuel normal cell operation; a buck converter that applies a second DC operating voltage to the fuel cell stack, the second DC operating voltage being stepped down from the first DC operating voltage of the high voltage electrical system to a voltage below the first voltage during normal fuel cell operation; and an FCS controller that is operable to send control signals to the boost converter and the buck converter. ### Claim 11 (depends on 10) The fuel cell charging system of claim 10 wherein the FCS controller is operable to disable the boost converter when the second DC operating voltage is applied to the fuel cell stack. ### Claim 12 (depends on 10) The fuel cell charging system of claim 10 further comprising a stack discharge circuit that when enabled reduces the voltage of the fuel cell stack through resistive energy discharge. ### Claim 13 (depends on 10) The fuel cell charging system of claim 10 wherein the FCS controller determines if the fuel cell stack voltage is within a predetermined voltage window having an upper voltage limit and a lower voltage limit. ### Claim 14 (depends on 13) The fuel cell charging system of claim 13 wherein the upper voltage limit is from 25 to 50 volts and the lower voltage limit is from 15 to 25 volts. ### Claim 15 (depends on 13) The fuel cell charging system of claim 13 wherein the predetermined voltage window is from 10 to 30 volts. ### Claim 16 (depends on 13) The fuel cell charging system of claim 13 wherein the FCS controller is operable to the buck converter to regulate the voltage of the fuel cell stack ### Claim 17 (depends on 13) The fuel cell charging system of claim 13 wherein the FCS controller is operable to perform diagnostic test when the fuel cell stack voltage is within the predetermined voltage window.