A power tool includes a brushless motor including several windings, a drive circuit for driving the brushless motor, a detection device for detecting the brushless motor so as to obtain a load parameter corresponding to a load of the brushless motor, and a controller for outputting a first control signal to reduce current of the brushless motor in a first slope when the load parameter exceeds a first preset range.

A motor device includes a motor having coils of three phases and a single-phase coil. The motor device includes a drive circuit of a first system capable of supplying a drive current to the coils of the three phases and a drive circuit of a second system capable of supplying a drive current to the single-phase coil. The drive circuit of the second system is different from the drive circuit of the first system. The drive circuit of the first system includes a three-phase inverter circuit connected to one end of each of the coils of the three phases, and the drive circuit of the second system includes a single-phase inverter circuit connected to both ends of the single-phase coil.

A half-bridge driver circuit is configured to generate drive signals based on control signals. A processing circuit is configured to generate high side and low side control signals based on a control signal. An edge detector is configured to generate first and second signals in response to rising and falling edges in the control signal. A state machine transitions between states in response to the first and second signals, and is configured to sequentially, in response to the first signal, set the high side and low side control signals low; in response to the second signal, set the high side control signal high and the low side control signal low; in response to the first signal, set the high side and low side control signals low; and in response to the second signal, set the high side control signal low and the low side control signal high.

A permanent-magnet synchronous machine comprises a rotor and a stator for holding at least one first stator winding and a second stator winding which is electrically insulated from said first stator winding. The second stator winding has a smaller conductor cross section and a larger number of turns than the first stator winding, wherein a first operating voltage is provided for motor operation of the first stator winding and a second operating voltage is provided for motor operation of the second stator winding. The second operating voltage has a higher rated voltage than a rated voltage of the first operating voltage.

In an embodiment, a motor driver comprises a multipurpose pin operable to couple the motor driver to a controller and judgment logic coupled to the multipurpose pin. The motor driver is operable to receive an input signal via the multipurpose pin and may be operable in a normal operation mode or a setting operation mode. The judgment logic may be operable to detect whether a prescribed pattern is present in the input signal, wherein the prescribed pattern indicates one of the normal operation mode or the setting operation mode, control at least a portion of the motor driver to operate in the setting operation mode when the prescribed pattern is detected in the input signal, and control at least the portion of the motor driver to operate in the normal operation mode when the prescribed pattern is not detected in the input signal.

An electric motor includes a stator, a rotor provided to be rotatable with respect to the stator, and a driving circuit board including a power IC applying a driving voltage to the stator, a Hall IC detecting a rotation position of the rotor, and a control IC adjusting a phase of the driving voltage in accordance with a magnetic-pole-position signal from the Hall IC and rotation speed information calculated on the basis of the magnetic-pole-position signal. The Hall IC is provided at a position at which an advance angle is larger than zero when a rotation speed of the rotor is zero.

A motor controller includes a motor drive circuit, a noise cancellation circuit, and a control unit. The motor drive circuit supplies electric power to an electric motor. The noise cancellation circuit includes an RLC circuit, a switch element, and a pull-down resistor. One end of the RLC circuit is electrically connected to a positive terminal of a power supply via the switch element, and the other end of the RLC circuit is electrically connected to a frame ground. A connection point between the RLC circuit and the switch element is electrically connected to a negative terminal of the power supply via the pull-down resistor. The control unit turns ON the switch element for a predetermined time at falling timings of phase voltages output from the motor drive circuit.

An electrical converter unit and a method for reducing thermal stress of a power semiconductor switch, such as an IGBT, of an electrical converter unit, the electrical converter unit comprising at least a gate control circuit wherein the electrical converter unit controls an electrical motor. The method comprises determining load and estimating required motor current based on the determined load and/or a predetermined speed profile. The electrical converter unit has at least a first operating state and a second operating state. The second operating state is used if predetermined criteria is fulfilled, the predetermined criteria relating to at least one of the following: estimated required current, measured motor speed, temperature of the power semiconductor switch and/or electrical converter unit, temperature model of the power semiconductor switch and/or electrical converter unit. In the second operating state a lower switching frequency of the power semiconductor switch is used than in the first operating state, and in the second operating state a higher switching speed of the power semiconductor switch is used than in the first operating state.

A control circuit has a three-phase modulation operation mode under which a three-phase modulation signal is output to an inverter circuit as a pulse width modulation signal, a two-phase modulation operation mode under which a two-phase modulation signal is output to the inverter circuit as the pulse width modulation signal, and a transitional operation mode under which one of the three-phase modulation operation mode and the two-phase modulation operation mode is switched to the other. The control circuit transitions to the transitional operation mode in response to a reference signal set in advance, and switches an operation by outputting to the inverter circuit, a transition modulation signal with a mixture ratio between the three-phase modulation signal and the two-phase modulation signal being gradually changed in a predetermined electrical angle interval unit.

A control device (2) for controlling power supply to a continuous-rotation motor, of the horological, DC type, is arranged to generate electrical pulses with a lower supply voltage to drive the rotor. The number of pulses per time interval is a function of the load applied to the motor. A voltage divider is arranged to supply the lower supply voltage with a plurality of different values and thus the electrical pulses with a variable voltage. A logic circuit counts the numbers of electrical pulses in successive time periods; to periodically select a voltage value, from among a plurality of different values, as a function of a counted number of electrical pulses or of a succession of counted numbers of electrical pulses; and to control the voltage divider so that the latter supplies the lower supply voltage with the selected voltage value after the selection of this voltage value.