A long-distance speed control system for a brushless DC motor of a fan is provided. The long-distance speed control system includes a switch connected with a mains power supply, a switch circuit, a voltage detection module, a power cord, a processing unit, and a drive unit, which can control the multi-stage rotational speed of the motor. In the field of brushless DC motors for fans, there is no need to use analog-to-digital conversion chips between the mains power supply and the processor, having the advantages of low cost, environmental protection, and reduction of waste of earth resources. Besides, the switch, the switch circuit and the power cord can withstand the mains power supply, having the advantages of less signal attenuation and long-distance transmission.

A long-distance speed control system for a brushless DC motor of a fan is provided. The long-distance speed control system includes a switch connected with a mains power supply, a switch circuit, a voltage detection module, a power cord, a processing unit, and a drive unit, which can control the multi-stage rotational speed of the motor. In the field of brushless DC motors for fans, there is no need to use analog-to-digital conversion chips between the mains power supply and the processor, having the advantages of low cost, environmental protection, and reduction of waste of earth resources. Besides, the switch, the switch circuit and the power cord can withstand the mains power supply, having the advantages of less signal attenuation and long-distance transmission.

An apparatus for treating a respiratory disorder in a patient includes a power supply, a first power supply circuit coupled to the power supply, a pressure generator to generate a flow of air, a transducer to generate a flow signal representing a property of the flow of air, and motor power supply circuitry. The motor power supply circuitry includes: a motor controller to control operation of a motor in the pressure generator based on the flow signal; one or more storage elements to store energy generated by motor deceleration; an energy dissipation circuit to dissipate a portion the energy generated by the deceleration of the motor; and an energy transfer circuit to couple the one or more storage elements to the first power supply circuit and transfer the energy generated by motor deceleration and/or the energy stored by the one or more storage elements to the first power supply circuit.

An apparatus for treating a respiratory disorder in a patient includes a power supply, a first power supply circuit coupled to the power supply, a pressure generator to generate a flow of air, a transducer to generate a flow signal representing a property of the flow of air, and motor power supply circuitry. The motor power supply circuitry includes: a motor controller to control operation of a motor in the pressure generator based on the flow signal; one or more storage elements to store energy generated by motor deceleration; an energy dissipation circuit to dissipate a portion the energy generated by the deceleration of the motor; and an energy transfer circuit to couple the one or more storage elements to the first power supply circuit and transfer the energy generated by motor deceleration and/or the energy stored by the one or more storage elements to the first power supply circuit.

A radial stabilizer is provided for stabilizing levitation passive bearing elements against lateral displacements. The stabilizer provides a means to introduce anisotropy in the radial stiffness of the stabilizer. The presence of anisotropic stiffness has a strongly stabilizing effect on whirl-type rotor-dynamic instabilities. The stabilizer design also provides a means for continuously monitoring the state of health of the rotor by signaling the onset of changes of balance that would be expected to precede any major failure.

A radial stabilizer is provided for stabilizing levitation passive bearing elements against lateral displacements. The stabilizer provides a means to introduce anisotropy in the radial stiffness of the stabilizer. The presence of anisotropic stiffness has a strongly stabilizing effect on whirl-type rotor-dynamic instabilities. The stabilizer design also provides a means for continuously monitoring the state of health of the rotor by signaling the onset of changes of balance that would be expected to precede any major failure.

An electric motor includes: a stator; a rotor; and a printed circuit board, pcb, mounted to an end of the motor, the motor end windings being provided as connections on the pcb. The motor further includes transient voltage suppression, TVS, components on the pcb.

A magnetic voltage/current limiting system is mounted in conjunction with a main coil, in a coil assembly of a wind turbine generator, for limiting the outputted voltage (or current) to a predetermined upper value. The limiting system generally has at least one limiting coil and a control circuit connected to the main coil. The limiting system is configured to be activated when the voltage (or current) outputted by the main coil increases beyond the predetermined upper value. Once activated, the limiting system diverts a portion of the outputted current to the limiting coil such as to generate a magnetic field in the limiting coil. This additional magnetic field generally limits the amount magnetic field generated by passing magnets to flow through the main coil, thereby limiting the outputted voltage.

A magnetic voltage/current limiting system is mounted in conjunction with a main coil, in a coil assembly of a wind turbine generator, for limiting the outputted voltage (or current) to a predetermined upper value. The limiting system generally has at least one limiting coil and a control circuit connected to the main coil. The limiting system is configured to be activated when the voltage (or current) outputted by the main coil increases beyond the predetermined upper value. Once activated, the limiting system diverts a portion of the outputted current to the limiting coil such as to generate a magnetic field in the limiting coil. This additional magnetic field generally limits the amount magnetic field generated by passing magnets to flow through the main coil, thereby limiting the outputted voltage.

An electric working machine according to one aspect of the present disclosure includes a motor, a current detector, a voltage detector, and a load state determination unit. The current detector is configured to detect a current flowing through the motor during drive of the motor. The voltage detector is configured to detect an input voltage supplied to the motor during drive of the motor. The load state determination unit is configured to determine whether the motor is in a no-load operation state based on the detected current, the detected input voltage and an output voltage from an electric power source.