CONTROLLER BY BATTERY DRIVE OF MOTOR DRIVEN TOOL

摘要

PURPOSE:To reduce the size of a heat sink plate by varying a duty ratio in response to a load current at the input of a gate terminal of a motor control MOSFET, thereby largely reducing the power loss of a drive transistor. CONSTITUTION:A motor 2, a MOSFET 3 and a current detecting resistor 4 are connected in series with a power source battery 1, a comparator 6 which inputs the output from a triangular wave generator 5 to the gate of the MOSFET 3 by converting it into a pulse of arbitrary duty ratio, and a duty ratio controller 7 for controlling the duty ratio of a pulse output from the comparator 6 proportional to the output from the resistor 4 are provided.