Disclosed is a hair dryer having a reverse blowing dust-removal function, comprising a housing, a fan module, an air inlet, and an air outlet. The housing has a pass-through airflow channel between the air inlet and the air outlet. The fan module is disposed within the airflow channel of the housing. A circuit control board is disposed within the housing. A microcontroller and a power supply drive module are disposed on the circuit control board. The power supply drive module is connected to the fan module. The micro-controller is connected to the power supply drive module. A reverse rotation button and a forward rotation button that are connected to the micro-controller are disposed on the housing. The micro-controller controls, in response to a reverse rotation signal output by the reverse rotation button, the fan module to rotate in a reverse direction by means of the power supply drive module.

The invention relates to a method for operating an electric machine (1), in particular of a motor vehicle, that has a stator (4) and a rotor (2), wherein the stator (4) has a stator winding (5) having at least three phases (U, V, W), and wherein the rotor is arranged/arrangeable on a rotor shaft (3), wherein a time-invariant differential equation modelling the machine (1) is taken as a basis for ascertaining a desired current value (I.sub.desired,fl) for the stator winding (5) for producing a required torque and/or a required rotation speed, wherein the desired current value (I.sub.desired,fl) is compared with an actual current value (I.sub.actual,fl) of the stator winding (5), which actual current value corresponds to electric phase currents (I.sub.U, I.sub.V, I.sub.W) flowing through the phases (U, V, W), and wherein the comparison is taken as a basis for passing current through the phases (U, V, W) such that a difference from the actual current value (I.sub.actual,fl) to the desired current value (I.sub.desired,fl) is reduced. There is provision for the time-invariant differential equation to be ascertained on the basis of a periodic, linear differential equation by means of a Floquet transformation.

A motor driving circuit and a motor driving method are provided. The motor driving circuit is used to drive the motor and includes an inverter circuit, a control circuit, a current-limiting circuit, a start circuit and a transient circuit. The control circuit controls the inverter circuit to drive the motor with a motor control current according to a set current limit value indicated by a current-limiting signal, and outputs a steady state ready signal in response to the motor reaching a steady state. The current-limiting circuit generates the current-limiting signal according to a start state signal, or generates the current-limiting signal according to a transient signal. The start circuit outputs the start state signal when the motor starts. The transient circuit detects whether the motor is in a transient state, and outputs the transient signal in response to the motor being in a transient state.

A power tool comprising a housing and a brushless direct-current (BLDC) motor disposed within the housing. The motor includes a stator and a rotor rotatable relative to the stator. The power tool is configured to generate a power output from the motor such that a quotient obtained by the power output measured in Watts (Wout), divided by an input measured in Volt-Amperes (Vain), and further divided by a diameter of the motor measured in meters (m), is greater than 10 Wout/Vain/m.

The invention relates to a method for the closed-loop and open-loop control of two or more EC motors operated using a common converter, wherein for the purpose of setting the operating point of the EC motors, common open-loop or closed-loop control using at least one controller is provided, wherein a combination of at least two control options is provided and in this case a controlled variable regulates the voltage setting at the output of the converter such that the two or more EC motors follow an intended sequence of operating points in a stable manner.

A power tool comprising a housing, a motor, and a circuit board residing in the housing is provided. A rectifier that receives an alternating current and converts the alternating current to a direct current, a switching arrangement having a plurality of motor switches connected electrically between the rectifier and the motor, and a capacitor connected electrically between the rectifier and the switching arrangement, are mounted on a rear portion of a planar surface of the circuit board. A switching arrangement and at least one heat sink in thermal communication therewith are mounted on a front portion of the planar surface of the circuit board.

A current limiting device includes a current limiter to limit a current to be carried to a drive within a range of a current limit value. The current limit value is set to change according to an acceleration of the drive.

There is provided herein an electrical motor and associated motor drive. The motor comprises an output shaft, and a speed sensor configured to measure the speed of the output shaft. The motor drive comprises a controller configured to output a current demand for the motor based on a speed error between a desired speed of the output shaft and the measured speed of the output shaft, and a feedback signal of the output current demand scaled by a first gain.

A motor driving circuit and a motor driving method are provided. The motor driving circuit is used to drive the motor and includes an inverter circuit, a control circuit, a current-limiting circuit, a start circuit and a transient circuit. The control circuit controls the inverter circuit to drive the motor with a motor control current according to a set current limit value indicated by a current-limiting signal, and outputs a steady state ready signal in response to the motor reaching a steady state. The current-limiting circuit generates the current-limiting signal according to a start state signal, or generates the current-limiting signal according to a transient signal. The start circuit outputs the start state signal when the motor starts. The transient circuit detects whether the motor is in a transient state, and outputs the transient signal in response to the motor being in a transient state.

A rotating electric machine control device has an electronic control unit, or an ECU that controls driving of a motor having motor windings, and includes mutually-communicable plural control units. The control unit includes a basic instruction calculation unit, a field-weakening calculation unit, and a current control calculation unit and a PWM (pulse width modulation) output unit. The current control calculation unit and the PWM output unit generate a PWM signal based on d-axis current instruction values and q-axis current instruction values that are calculated based on basic current instruction values and field-weakening d-axis current instruction value. At least a part of the instruction values used for generation of the PWM signal is shared by the plural control units.