Johnson Electric S.a.

Johnson Electric International Ag

Techtronic Cordless Gp

Hai Bo Ma

Yong Li

Tao Zhang

Yong Gao

Yuk Tung Lo

Rui Feng Qin

Song Ping Chen

Jie Chai

Xin Hui Guan

Qiang Zhou

Jin Yun Gan

Jing Li

Siu Chung Yip

Hai Ming Luo

Jian Xun Zou

Wei Long Lan

Ka Lung Ng

Yu Quan Liang

Song Chen

A method of controlling a sensorless motor (). The method contains the steps of determining a current speed of the motor (); selectively using a first method, a second method, or a third method to determine a position of a rotor of the motor (), depending on the current speed of the motor (); and transmitting a drive signal to the motor () based on the determined position of the rotor. A sensorless motor assembly is also disclosed. According to the method, multiple rotor position detection methods are provided to the sensorless motor () which cover a full speed range of the motor ().

Sensorless motor assembly and method of controlling the same

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 circuit includes a first operating component, a second operating component and a starting time control circuit. The starting voltage of the first operating component is different from that of the second operating component, and the starting time control circuit is configured to regulate a starting time of the first operating component to be synchronous with that of the second operating component.

Electronic device having delay circuit for synchronous starting of two operating components

A power tool and a motor drive circuit thereof are provided. The motor drive circuit includes an inverter, a controller and a current sensor. The inverter includes a plurality of semiconductor switches and configured to convert a voltage from a power supply into an alternating current for an electric motor. The controller is configured to output detecting signals and drive signals for the inverter. The current sensor is configured to sample a current flowing through the motor, the current comprising a plurality of driving current portions corresponding to the drive signals and a plurality of position detecting current portions corresponding to the detecting signals. The controller determines the drive signals at least based on the position detecting current portions of the current so as to control power modes of the semiconductor switches in the inverter in a starting stage of the motor.

Power tool and motor drive circuit thereof

A commutatorfor an electric motor comprises a plurality of commutator segments supported by a base. The segments have an electrically conductive body portionand at least one electrically conductive foldable tangprovided on the body portionfor engaging a winding lead wireof an electric motor. The foldable tanghas a proximal endon or adjacent to the body portion, and a distal endremote from the proximal end. A wire-accommodating portionis provided on or adjacent to the foldable tang, so that, when the tangis folded, the wire-accommodating portion provides a predetermined gapfor the winding lead wire

Electric motor commutator

Growing community of inventors

Hong Kong, China

Hai Bo Ma