A power adapter is provided to supply electric power from an alternating current from an alternating current (AC) power supply to a powered apparatus. It includes a switchable capacitor circuit housed within a housing and including a switchable capacitor switchably coupled across the AC power supply and a H-bridge circuit including four switches. An OFF-state of the four switches creates a charging path for the switchable capacitor, an ON-state of a first pair of the four switches creates a discharge path for the switchable capacitor during a positive half cycle of the alternating current, and an ON-state of a second pair of the four switches creates a discharge path for the switchable capacitor during a negative half cycle of the alternating current.

A power tool has a functional component, a motor, a power supply module, a controller and a drive circuit including a first drive terminal and a second drive terminal respectively electrically connected to a first power terminal and a second power terminal of the power supply module, multiple high-side switches wherein high-side terminals of the high-side switches are respectively electrically connected to the first drive terminal, and multiple low-side switches wherein low-side terminals of the low-side switches are respectively electrically connected to the second drive terminal. The controller is configured to output a first control signal to one high-side switch to place it in an on or off state and output a second control signal to one low-side switch to place it in the other state. The low-side terminal of one high-side switch is connected to the high-side terminal of one low-side switch.

A motor driving circuit includes a rotation speed request generator, a motor driving signal generating unit, an inverter circuit, a position detecting circuit, a current detecting module, a rotation speed signal lookup module, an automatic leading angle controller, and a modulation signal generating circuit. When the rotation speed request signal indicates that a rotation speed of a motor is adjusted to a current rotation speed, the rotation speed signal lookup module queries a lookup table and generates a leading angle indication signal for indicating a current leading angle as a adjusting angle, and the automatic leading angle controller generates a phase adjusting signal, and the modulation signal generation circuit roughly adjusts a modulation waveform with the adjusting phase. The modulation signal generating circuit performs a fine adjustment on the modulation waveforms according to a phase difference, thereby making the current zero-crossing point near the BEMF zero point.

An example motor includes: a rotor with a plurality of alternate polarity permanent magnets; and a stator forming a like number of poles. The stator forms one or more biasing features concentrating magnetic flux at at least one location. In some examples, the stator has an interior surface unbroken by locating features, and the stator has one or more openings that form the one or more biasing features.

A power tool is provided including: an electric brushless direct current (BLDC) motor having a rotor and a stator. The stator includes at least six teeth including a first set of teeth on which a first set of stator windings are wound and a second set of teeth on which a second set of stator windings are wound. The first and second sets of stator windings are alternatingly arranged relative to the stator. The first set of stator windings is connected in a wye configuration and the second set of stator windings is connected in delta configuration.

An operation controlling apparatus of a reciprocating compressor includes: a detector configured to detect a torque output by a motor of the reciprocating compressor, a rotation speed of the motor, a counter electromotive voltage of the motor, and a current applied to the motor; a controller configured to determine a mode switching time point for switching an operation mode of the reciprocating compressor based on the torque, the rotation speed, the counter electromotive voltage, and the current of the motor, and output a control signal for changing a wire ratio of the motor corresponding to the operation mode; and a driver configured to change the wire ratio of the motor based on the control signal and operate the reciprocating compressor in the operation mode among at least two operation modes.

An electromagnetic rotating apparatus may include an electromagnet winding that consumes power generated during regeneration. A motor voltage monitoring circuit detects that a voltage at a motor driving main circuit is higher than a voltage during normal operation, due to overshoot or the like after arrival at a set speed during deceleration or acceleration of a motor. The motor voltage monitoring circuit transmits a high-voltage detection signal to a braking current adjusting circuit and a magnetic bearing control circuit. Upon receiving the high-voltage detection signal, the braking current adjusting circuit reduces a braking current command value for the motor so as to maintain an excitation voltage for the motor constant or reduce this excitation voltage, and an amplifier control circuit in the magnetic bearing control circuit increases a bias current flowing through an electromagnet winding to increase power consumption.

A motor controller includes: a rotation speed measurement portion that measures a rotation speed of a motor; and an energization method switching portion that switches an energization method so that the motor is driven by a 120-degree energization method when a rotation speed of the motor measured by the rotation speed measurement portion is less than or equal to a predetermined threshold value, and the motor is driven by a 150-degree energization method when a rotation speed of the motor measured by the rotation speed measurement portion exceeds the predetermined threshold value.

A six-wire three-phase motor that can realize both of increasing an output and reducing a torque ripple is provided. A six-wire three-phase motor is a six-wire three-phase motor including: a stator including a winding wire wound independently between phases; and a rotor including a plurality of magnets in a circumferential direction, wherein the stator or the rotor is configured in such a manner that a third harmonic current component in a motor current of when an overmodulation voltage based on a PWM signal is applied becomes higher than a third harmonic current component in a motor current of when a sinusoidal modulation voltage based on the PWM signal is applied.

A permanent-magnet three-phase duplex motor is provided with two systems, namely a system that includes a first three-phase winding and a first inverter circuit, and a system that includes a second three-phase winding and a second inverter circuit, and a controlling apparatus is configured such that when one system fails, the controlling apparatus stops operation of the inverter circuit of the failed system, and controls operation of the inverter circuit of the normal system to increase the driving current that is supplied from the inverter circuit of the normal system, and the first three-phase winding and the second three-phase winding are configured such that magnetic fields that act on the permanent magnets in a demagnetizing direction when the increased driving current is supplied from the inverter circuit of the normal system are equal to magnetic fields that normally act on the permanent magnets in the demagnetizing direction.