Alternator overvoltage protection circuit

Patent metadata

Field	Value
Publication number	US-9537436-B2
Application number	US-201514885386-A
Country	US
Kind code	B2
Filing date	Oct 16, 2015
Priority date	Jan 5, 2013
Publication date	Jan 3, 2017
Grant date	Jan 3, 2017

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.

First claim

What is claimed is:

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;

said MOSFET is electrically connected to an alternator, wherein said MOSFET is configured to conduct when said alternator operates in an overvoltage condition; and
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; and
wherein said MOSFET is configured to conduct when a voltage is imposed on a gate of said MOSFET by said conducting transistor; and wherein said MOSFET is configured to direct a portion of current from said magneto to trigger a gate of said TRIAC when said MOSFET is conducting, wherein a first voltage at a gate of said TRIAC and a second voltage at a first terminal of said TRIAC are less than a third voltage at a second terminal of said TRIAC causing said TRIAC to conduct.

2. 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.

3. 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.

4. The alternator overvoltage circuit of claim 1 , wherein said overvoltage condition is present when said alternator outputs a voltage greater than about 18.65VDC.

5. The alternator overvoltage circuit of claim 1 , wherein said overvoltage condition is present when said alternator outputs a voltage greater than about 15 VDC.

6. The alternator overvoltage circuit of claim 1 , wherein said overvoltage condition is present when said alternator outputs a voltage greater than about 20 VDC.

Assignees

• Mtd Products Inc

Inventors

• Guadiz Maynard S

Classifications

• H02H7/09

  against over-voltage; against reduction of voltage; against phase interruption · CPC title

• H02P9/04

  Control effected upon non-electric prime mover and dependent upon electric output value of the generator · CPC title

• H02H3/202

  for DC systems · CPC title

• H02P9/006 Primary

  Means for protecting the generator by using control (control effected upon generator excitation circuit to reduce harmful effects of overloads or transients H02P9/10) · CPC title

• H02H7/065

  against excitation faults · CPC title