# US 11,067,640 B2 · Loss of ground detection system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,067,640 B2 - Document ID: US11067640B2 - Status: Granted - Kind: B2 - Application number: 16/021,638 - Filed: 2018-06-28 - Published: 2020-01-02 - Granted: 2021-07-20 - Earliest claimed: 2018-06-28 - Assignees: Lear Corporation - Applicants: Lear Corporation - Inventors: Daniel Ruiz-Garcia; Josep Benet-Freissinier; Sergio Alquezar-Alquezar; Victor Navarro-Cases; Alberto Martinez-Ramirez; Jordi Agusti-Batlle - Web page: https://patentgrep.com/patent/US11067640B2 ## CPC - G01R 31/52: Testing for short-circuits, leakage current or ground faults - B60L 3/0069: {relating to the isolation, e.g. ground fault or leak current} - G05B 19/048: Monitoring; Safety - G05B 2219/24133: Ground each module and total system - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) - 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 - G05B: CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS (systems for controlling or regulating non-electric variables G05D; systems for regulating electric or magnetic variables G05F; control devices or systems insofar as characterised by mechanical features only G05G) ## Abstract A loss of ground detection system includes a reference voltage source that provides a reference voltage, a primary ground connection that is adapted to be connected to a primary ground, a secondary ground connection that is adapted to be connected to a secondary ground, and an internal ground. The system also includes a combined ground integrity monitoring unit that outputs a multistage signal to control electronics. The multistage signal includes a first and a second output voltage. A first switch is interposed between the primary ground connection and the internal ground such that the first switch opens in response to loss of connection to the primary ground as indicated by a change of status in multistage signal, a diode system is interposed between the secondary ground connection and the internal ground, the diode system oriented to allow flow from the internal ground to secondary ground connection under forward bias. ## Claims ### Claim 1 A loss of ground detection system comprising: a reference voltage source providing a reference voltage; a primary ground connection connected to a primary ground; a secondary ground connection connected to a secondary ground; an internal ground; a combined ground integrity monitoring unit that outputs a multistage signal to control electronics, the combined ground integrity monitoring unit interposed between and in electrical communication with the reference voltage source and both of the primary ground connection and the secondary ground connection, the multistage signal including a first output voltage and a second output voltage; wherein the combined ground integrity monitoring unit includes: a first ground connection integrity monitoring stage and a second ground connection integrity monitoring stage; wherein the first ground connection integrity monitoring stage is a first voltage divider and the second ground connection integrity monitoring stage is a second voltage divider; wherein the control electronics comprises an A to D converter; a first transistor switch interposed between the primary ground connection and the internal ground such that the first transistor switch opens in response to loss of connection to the primary ground as indicated by a change of status in the multistage signal; and a diode system interposed between the secondary ground connection and the internal ground, the diode system oriented to allow flow from the internal ground to the secondary ground connection under forward bias. ### Claim 2 (depends on 1) The loss of ground detection system of claim 1, wherein the first ground connection integrity monitoring stage outputs the first output voltage, the first ground connection integrity monitoring stage being interposed between and in electrical communication with the primary ground connection and the reference voltage source; and the second ground connection integrity monitoring stage outputs the second output voltage, the second ground connection integrity monitoring stage being interposed between and in electrical communication with the secondary ground connection and reference voltage source. ### Claim 3 (depends on 1) The loss of ground detection system of claim 1, wherein the secondary ground connection provides a backup path to ground for the loss of ground detection system. ### Claim 4 (depends on 3) The loss of ground detection system of claim 3, further comprising a second transistor switch positioned between the reference voltage source and both the first voltage divider and the second voltage divider, the second transistor switch allowing the loss of ground detection system to be actuated when desired. ### Claim 5 (depends on 1) The loss of ground detection system of claim 1, wherein there is a voltage drop of less than 0.5 volts from internal ground connection to primary ground connection across the first transistor switch during normal operation in a vehicle in which there is no loss of ground, current flowing from the internal ground to the primary ground connection. ### Claim 6 (depends on 1) The loss of ground detection system of claim 1, wherein a loss of ground at the primary ground connection causes the second output voltage to drop. ### Claim 7 (depends on 6) The loss of ground detection system of claim 6, wherein a first current flows through the first transistor switch to internal ground. ### Claim 8 (depends on 7) The loss of ground detection system of claim 7, wherein the diode system includes a first diode a second diode in series. ### Claim 9 (depends on 1) The loss of ground detection system of claim 1, wherein a loss of ground at the secondary ground connection causes the second output voltage to rise to a value of the reference voltage plus or minus 10%. ### Claim 10 (depends on 4) The loss of ground detection system of claim 4, further comprising a third transistor switch that controls the first transistor switch. ### Claim 11 (depends on 1) The loss of ground detection system of claim 1, wherein the primary ground connection is attached to a primary vehicle chassis ground. ### Claim 12 A method for determining ground loss by a loss of ground detection system that includes: a reference voltage source providing a reference voltage; a primary ground connection connected to a primary ground; a secondary ground connection connected to a secondary ground; an internal ground; and a combined ground integrity monitoring unit that outputs a multistage signal to control electronics, the combined ground integrity monitoring unit interposed between and in electrical communication with the reference voltage source and both of the primary ground connection and the secondary ground connection, the multistage signal including a first output voltage and a second output voltage, the method comprising: a) measuring the first output voltage and the second output voltage after the loss of ground detection system is installed in a target system; b) determining that the primary ground connection is disconnected from the primary ground if the second output voltage is lower than a second predetermined threshold voltage c) disconnecting the internal ground from primary ground connection if the second output voltage has fallen below the second predetermined threshold voltage; d) determining that the primary ground connection is disconnected from ground if the first output voltage is higher than a third predetermined threshold voltage; and e) reconnecting the primary ground connection to primary ground if the first output voltage is not above the third predetermined threshold voltage; wherein the combined ground integrity monitoring unit includes: a first ground connection integrity monitoring stage and a second ground connection integrity monitoring stage; wherein the first ground connection integrity monitoring stage is a first voltage divider and the second ground connection integrity monitoring stage is a second voltage divider; and wherein the control electronics comprises an A to D converter. ### Claim 13 (depends on 12) The method of claim 12, the first ground connection integrity monitoring stage outputs the first output voltage, the first ground connection integrity monitoring stage being interposed between and in electrical communication with the primary ground connection and the reference voltage source; and the second ground connection integrity monitoring stage outputs the second output voltage, the second ground connection integrity monitoring stage being interposed between and in electrical communication with the secondary ground connection and reference voltage source. ### Claim 14 (depends on 13) The method of claim 13, wherein the secondary ground connection provides a backup path to ground for the loss of ground detection system. ### Claim 15 (depends on 13) The method of claim 13, wherein the loss of ground detection system further comprises a first transistor switch interposed between the primary ground connection and the internal ground such that the first transistor switch opens in response to loss of connection to the primary ground as indicated by a change of status in multistage signal. ### Claim 16 (depends on 15) The method of claim 15, wherein the loss of ground detection system further comprises a second transistor switch positioned between the reference voltage source and both the first voltage divider and the second voltage divider, the second transistor switch allowing the loss of ground detection system to be actuated when desired. ### Claim 17 (depends on 15) The method of claim 15, wherein a loss of ground at the primary ground connection causes the second output voltage to drop, wherein a first current flows through the first transistor switch to internal ground. ### Claim 18 (depends on 17) The method of claim 17, wherein the loss of ground detection system further comprises a diode system interposed between the secondary ground connection and the internal ground, the diode system oriented to allow flow from the internal ground to secondary ground connection under forward bias. ### Claim 19 (depends on 12) The method of claim 12, further comprising determining that the secondary ground connection is disconnected from ground if the second output voltage is higher than a first predetermined threshold voltage prior to step b).