Abstract: 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.

Abstract: 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.

Abstract: A motor control system controls power supplying of a motor. The motor control system is configured to control the motor be excited in advance of a zero crossing of a back electromotive force by an advance angle, and the advance angle gradually increases from an acceleration mode to a constant speed operating mode after the motor is started. The motor control system is further configured to control the motor to be excited within a conduction angle, and the conduction angle gradually reduces to a pre-determined value from the acceleration mode to the constant speed operating mode after the motor is started.

Abstract: A motor control system includes a drive controller and an inverter having two half bridges. When an excitation voltage for a motor is inverted or the motor is freewheeled, the drive controller turns off one semiconductor switch and turns on the other semiconductor switch after delaying for a delay angle in same half-bridge.

Abstract: 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.

Abstract: A cooking appliance (10) includes a housing (12), a food process area (14) inside the housing, a heat source (22, 504), a low voltage DC motor (18, 510, 610) driving an impeller (16) disposed upstream of the heat source to circulate air and convectively transfer heat for preparing food In one embodiment, the heat source (22), serving as a voltage divider, and a shunt (24), cooperate to regulate the voltage and current input for driving the low voltage DC motor (18). In another embodiment, the heat source (504, 604) is connected across an AC power source (502, 602) and a voltage divider (506, 606) regulates the voltage input to the low voltage DC motor (510, 610).

Abstract: 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.