Protective redundant subsystem for power tools
US9071188B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 3, 2010 |
| Grant date | Jun 30, 2015 |
| Priority date | — |
| Expiry date | May 16, 2032 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH02H7/093
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
A protective redundancy circuit is provided for a power tool having an electric motor. The protective redundant subsystem is comprised of: a motor switch coupled in series with the motor; a motor control module that controls the switching operation of the motor switch; and a protective control module that monitors switching operation of the motor switch and disables the power tool when the switching operation of the motor switch fails. In the context of an AC powered tool, the switching operation of the motor switch is correlated to and synchronized to the waveform of the AC input signal. During each cycle or half cycle, the motor control module introduces a delay period before closing the motor switch and the protective control module determines the operational status of the motor switch by measuring the voltage across the motor switch during the delay period.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.