Johnson Electric S.a.

Johnson Electric International Ag

Siu Chung Yip

Chi Ping Sun

Song Ping Chen

Fang Li

Yong Gao

Hai Bo Ma

Yuk Tung Lo

Jian Xun Zou

Song Chen

An electric tool and a motor drive system are provided. The motor drive system includes a trigger switch, an electronic switch, and a switch control circuit connected between the trigger switch and the electronic switch. The trigger switch is connected in series to a power supply. The electronic switch is configured to control a motor to be powered on or powered off. The switch control circuit is configured to control the electronic switch based on a state of the trigger switch, wherein the electronic switch is delayed to be turned off after the trigger switch is turned off to control the motor to be powered off later than a time that the trigger switch is turned off.

Electric tool and motor drive system

A fan for a ventilation system has a motor, a motor speed control unit and a controller arranged to control the motor to maintain the quantity of air flowing through the system constant. The controller compares the actual motor current with an expected motor current for the fan operating at the desired air quantity and motor speed to determine an actual system operating condition. When the difference between the actual motor current and the expected motor current is greater than a preset range, the motor speed is adjusted to a new motor speed determined based on the actual system operating condition. The system operating conditions may change due to changes in the static pressure of the system such as changes to the ventilation ducting or external wind pressure.

Growing community of inventors

Hong Kong, China

Siu Chung Yip