# US 2014/0191700 A1 · Operating state circuit for inverter and method for setting operating states of an inverter > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0191700 A1 - Document ID: US20140191700A1 - Status: Published application - Kind: A1 - Application number: 14/239,428 - Filed: 2012-06-12 - Published: 2014-07-10 - Earliest claimed: 2011-08-18 - Assignees: Robert Bosch GmbH - Inventors: Edwin Eberlein; Andreas Schoenknecht; Daniel Raichle - Web page: https://patentgrep.com/patent/US20140191700A1 ## CPC - H02P 27/06: using DC to AC converters or inverters (H02P27/05 takes precedence) - B60L 3/0061: {relating to electrical machines} - H02H 7/08: for dynamo-electric motors - H02P 3/22: by short-circuit or resistive braking - H02P 6/182: using back-emf in windings - H02P 29/0241: {the fault being an overvoltage} - H02M 1/32: Means for protecting converters other than automatic disconnection - H02P 2207/05: Synchronous machines, e.g. with permanent magnets or DC excitation - Y02T 10/64: Electric machine technologies in electromobility - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS - B60L: PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES (arrangements or mounting of electrical propulsion units or of plural diverse prime-movers for mutual or common propulsion in vehicles B60K1/00, B60K6/20; arrangements or mounting of electrical gearing in vehicles B60K17/12, B60K17/14; preventing wheel slip by reducing power in rail vehicles B61C15/08; dynamo-electric machines H02K; control or regulation of electric motors H02P); SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES (electric coupling devices combined with mechanical couplings of vehicles B60D1/64; electric heating for vehicles B60H1/00); ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL (control or regulation of electric motors H02P); MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES - H02H: EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS (indicating or signalling undesired working conditions G01R, e.g. G01R31/00, G08B; locating faults along lines G01R31/08; emergency protective devices H01H) - 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) - Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION ## Abstract The invention relates to an operating state circuit for actuating an inverter (3), which supplies an n-phase electrical machine (5) with an n-phase supply voltage via phase connections (4a, 4b, 4c), wherein n≧1, comprising an evaluation device (6) which is connected to the phase connections (4a, 4b, 4c) of the inverter (3) and which is configured to detect output voltages of the inverter (3) to the phase connections (4a, 4b, 4c) and to determine a speed of the electrical machine (5) on the basis of the detected output voltages, and an actuating device (7) which is coupled to the evaluation device (6) and which is configured to switch to an idle state or an active short-circuit in dependence on the determined speed of the inverter (3). ## Claims ### Claim 1 An operating state circuit for driving an inverter, which supplies an n-phase supply voltage to an n-phase electric machine via phase connections, where n≧1, the circuit comprising: an evaluation device connected to the phase connections of the inverter and designed to detect output voltages of the inverter at the phase connections and to determine a speed of the electric machine on the basis of the detected output voltages; and a drive device coupled to the evaluation device and designed to switch the inverter into at least one of the group including a freewheeling state and an active short circuit, in dependence on the determined speed. ### Claim 2 (depends on 1) The operating state circuit as claimed in claim 1, wherein the drive device is designed to switch the inverter into a freewheeling state when the determined speed is less than a predetermined speed threshold value and to switch the inverter into an active short circuit when the determined speed is greater than or equal to the predetermined speed threshold value. ### Claim 3 (depends on 1) The operating state circuit as claimed claim 1, wherein the evaluation device is designed to detect the field emf of the electric machine. ### Claim 4 (depends on 1) The operating state circuit as claimed in claim 1, wherein the evaluation device comprises a microcontroller. ### Claim 5 (depends on 1) An inverter arrangement for supplying an n-phase supply voltage to an n-phase electric machine, where n≧1, the inverter arrangement comprising: a DC voltage intermediate circuit, to which a DC voltage is supplied from a high-voltage source; an inverter comprising a multiplicity of switching devices, which is connected to the DC voltage intermediate circuit and is designed to provide an n-phase supply voltage at phase connections; an operating state circuit as claimed in claim 1, which is designed to drive the multiplicity of switching devices of the inverter for setting a freewheeling state or an active short circuit; and an energy supply device, which is coupled to the DC voltage intermediate circuit and which is designed to supply electrical energy from the DC voltage intermediate circuit to the evaluation device and the drive device. ### Claim 6 (depends on 5) The inverter arrangement as claimed in claim 5, wherein the drive device is designed to switch the switching devices of the inverter into a freewheeling mode for a predetermined time period when the DC voltage in the DC voltage intermediate circuit falls below an intermediate circuit threshold value. ### Claim 7 A method for setting operating states of an inverter, which supplies an n-phase supply voltage to an n-phase electric machine via phase connections, where n≧1, the method comprising: detecting output voltages at the phase connections of the inverter; determining a speed of the electric machine on the basis of the detected output voltages; driving switching devices of the inverter for setting a freewheeling state when the determined speed is less than a predetermined speed threshold value; and driving switching devices of the inverter for setting an active short circuit when the determined speed is greater than or equal to the predetermined speed threshold value. ### Claim 8 (depends on 7) The method as claimed in claim 7, wherein the driving of the switching devices is only implemented when a fault state of the electric machine is detected. ### Claim 9 (depends on 7) The method as claimed in claim 7, further comprising the following steps: determining a DC voltage of a DC voltage intermediate circuit, which is connected to the input connections of the inverter; and driving switching devices of the inverter for setting the freewheeling state for a predetermined time period when the determined DC voltage is below a predetermined intermediate circuit threshold value. ### Claim 10 (depends on 7) The method as claimed in claim 7, wherein the step of detecting the output voltages comprises detecting the field emf of the electric machine (5).