# US 2014/0192442 A1 · Alternator Overvoltage Protection Circuit > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0192442 A1 - Document ID: US20140192442A1 - Status: Published application - Kind: A1 - Application number: 14/147,223 - Filed: 2014-01-03 - Published: 2014-07-10 - Earliest claimed: 2013-01-05 - Assignees: MTD Products Inc - Applicants: MTD Products Inc - Inventors: Maynard S. Guadiz - Web page: https://patentgrep.com/patent/US20140192442A1 ## CPC - H02P 9/006: {Means for protecting the generator by using control (control effected upon generator excitation circuit to reduce harmful effects of overloads or transients H02P9/10)} - F02D 29/06: peculiar to engines driving electric generators - H02H 3/202: {for DC systems} - H02H 7/065: {against excitation faults} - H02H 7/067: {on occurrence of a load dump (control on sudden change of load H02P9/10)} - H02H 7/09: against over-voltage; against reduction of voltage; against phase interruption - H02P 9/04: Control effected upon non-electric prime mover and dependent upon electric output value of the generator - A01D 34/64: mounted on a vehicle, e.g. a tractor, or drawn by an animal or a vehicle (A01D34/695 takes precedence) - H02P 2101/45: for motor vehicles, e.g. car alternators - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS - F02D: CONTROLLING COMBUSTION ENGINES (vehicle fittings, acting on a single sub-unit only, for automatically controlling vehicle speed B60K31/00; conjoint control of vehicle sub-units of different type or different function, road vehicle drive control systems for purposes other than the control of a single sub-unit B60W) - 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) - A01D: HARVESTING; MOWING ## Abstract Disclosed is an alternator overvoltage protection circuit having a TRIAC and a MOSFET. The TRIAC is electrically connected to the MOSFET and the TRIAC is electrically connected to a magneto. The TRIAC is configured to ground the magneto when triggered by the MOSFET. The MOSFET is electrically connected to an alternator and configured to conduct when the alternator operates in an overvoltage condition. Also disclosed is a method of alternator overvoltage protection for a piece of outdoor power equipment, the method including providing a TRIAC and an alternator rotated by an engine having a magneto, wherein the alternator outputs a voltage when rotated by the engine. The method further includes configuring the TRIAC to ground the magneto when the alternator operates in an overvoltage condition, thereby disabling the magneto, which stops the rotation of the engine and stops the alternator from outputting voltage. ## Claims ### Claim 1 An alternator overvoltage protection circuit comprising: a TRIAC and a MOSFET; said TRIAC is electrically connected to said MOSFET, said TRIAC is electrically connected to a magneto, wherein said TRIAC is configured to ground said magneto when triggered by said MOSFET; and said MOSFET is electrically connected to an alternator, wherein said MOSFET is configured to conduct when said alternator operates in an overvoltage condition. ### Claim 2 (depends on 1) The alternator overvoltage protection circuit of claim 1, wherein said alternator is connected to and rotated by an engine, wherein said magneto is connected to and provides spark to said engine. ### Claim 3 (depends on 2) The alternator overvoltage protection circuit of claim 2, wherein said alternator provides a voltage output; wherein grounding said magneto with said TRIAC disables said magneto and stops said voltage output from said alternator. ### Claim 4 (depends on 3) The alternator overvoltage protection circuit of claim 3, further comprising a transistor; wherein said transistor is electrically connected to said alternator, wherein said transistor is configured to conduct when said alternator operates in said overvoltage condition. ### Claim 5 (depends on 4) The alternator overvoltage circuit of claim 4, wherein said overvoltage condition is present when said alternator outputs a voltage greater than about 18.65 VDC. ### Claim 6 (depends on 4) The alternator overvoltage circuit of claim 4, wherein said overvoltage condition is present when said alternator outputs a voltage greater than about 15 VDC. ### Claim 7 (depends on 4) The alternator overvoltage circuit of claim 4, wherein said overvoltage condition is present when said alternator outputs a voltage greater than about 20 VDC. ### Claim 8 An alternator overvoltage protection circuit comprising: a TRIAC and a MOSFET; said TRIAC is electrically connected to said MOSFET, said TRIAC is electrically connected to a magneto, wherein said TRIAC is configured to ground said magneto when triggered by said MOSFET; and said MOSFET is electrically connectable to an alternator, wherein said MOSFET is configured to conduct when said alternator operates in an overvoltage condition. ### Claim 9 (depends on 8) The alternator overvoltage protection circuit of claim 8, wherein said alternator is connected to and rotated by an engine, wherein said magneto is connected to and provides spark to said engine. ### Claim 10 (depends on 9) The alternator overvoltage protection circuit of claim 9, wherein said alternator provides a voltage output; wherein grounding said magneto with said TRIAC disables said magneto and stops said voltage output from said alternator. ### Claim 11 (depends on 10) The alternator overvoltage protection circuit of claim 10, further comprising a transistor; wherein said transistor is electrically connectable to said alternator, wherein said transistor is configured to conduct when said alternator operates in said overvoltage condition. ### Claim 12 (depends on 11) The alternator overvoltage circuit of claim 11, wherein said overvoltage condition is present when said alternator outputs a voltage greater than about 18.65 VDC. ### Claim 13 (depends on 11) The alternator overvoltage circuit of claim 11, wherein said overvoltage condition is present when said alternator outputs a voltage greater than about 15 VDC. ### Claim 14 (depends on 11) The alternator overvoltage circuit of claim 11, wherein said overvoltage condition is present when said alternator outputs a voltage greater than about 20 VDC. ### Claim 15 A method of alternator overvoltage protection comprising: providing a TRIAC and an alternator rotated by an engine having a magneto, wherein said alternator outputs a voltage when rotated by said engine; and configuring said TRIAC to ground said magneto when said alternator operates in an overvoltage condition, thereby disabling said magneto, stopping the rotation of said engine, and stopping said alternator from outputting voltage. ### Claim 16 (depends on 15) The method of claim 15 further comprising: providing a transistor and a MOSFET; configuring said transistor to conduct when said alternator operates in said overvoltage condition; configuring said MOSFET to conduct when a voltage is imposed on a gate of said MOSFET by said conducting transistor; and configuring said MOSFET to direct a portion of current from said magneto to trigger a gate of said TRIAC when said MOSFET is conducting, thereby causing said TRIAC to conduct. ### Claim 17 (depends on 16) The method of claim 16, wherein said overvoltage condition is present when said alternator output voltage is greater than about 18.65 VDC. ### Claim 18 (depends on 16) The method of claim 16, wherein said overvoltage condition is present when said alternator output voltage is greater than about 15 VDC. ### Claim 19 (depends on 16) The method of claim 16, wherein said overvoltage condition is present when said alternator output voltage is greater than about 20 VDC.