A method for estimating the temperature of a stator coil of a magnetic suspension bearing of a rotor that is connected by connection wires to circuits for servo-controlling the position of the rotor includes the following steps: measuring the electric voltage at the terminals of the connection wires of the stator coil; measuring the intensity of the current passing through the stator coil; estimating the electric resistance of the stator coil and of the connection wires on the basis of an adaptive filter, the measured electric voltage and the intensity of the measured current; and estimating the temperature of the coil on the basis of the value of the estimated resistance.

An electric motor system includes a drive shaft, first and second magnetic bearing portions facing each other and supporting the drive shaft, an electric motor to rotate the drive shaft, and a gap detection unit to detect a position of the drive shaft During rotation of the drive shaft, greater external force acts, on average, on the drive shaft in a first direction than in a second direction. The first and second direction extend from the second and first magnetic bearing portions to the first and second magnetic bearing portion. The first and second magnetic bearing portions produce first and second magnetic forces on the drive shaft in the first and second directions. A magnitude of the second magnetic force is greater than a magnitude of the first magnetic force. The gap detection unit is arranged closer to the second magnetic bearing portion than to the first magnetic bearing portion.

An electric motor system includes a drive shaft, first and second magnetic bearing portions facing each other and supporting the drive shaft, an electric motor to rotate the drive shaft, and a gap detection unit to detect a position of the drive shaft During rotation of the drive shaft, greater external force acts, on average, on the drive shaft in a first direction than in a second direction. The first and second direction extend from the second and first magnetic bearing portions to the first and second magnetic bearing portion. The first and second magnetic bearing portions produce first and second magnetic forces on the drive shaft in the first and second directions. A magnitude of the second magnetic force is greater than a magnitude of the first magnetic force. The gap detection unit is arranged closer to the second magnetic bearing portion than to the first magnetic bearing portion.

Provided are a vacuum pump, a magnetic bearing device, and a rotor that suppress swinging and vibration of a rotor. A vacuum pump includes, in the following order in the exhaust direction of a gas, the center of gravity of a rotor, an active radial bearing that supports the rotor in the radial direction in a non-contact manner by using a magnetic force, and a passive radial bearing that supports the rotor in the radial direction in a non-contact manner using a magnetic force.

The present disclosure provides a vacuum pump with which size and weight reduction, improvement of workability, and cost reduction can be realized. Electrical connection between a pump main body that has a rotor supported by a magnetic bearing and a control unit that controls the drive of the pump main body is established by a flexible printed wiring board configured by printing an electric circuit on a surface of a sheet-like insulating substrate.

Disclosed is a method for calibrating at least one gap sensor, the at least one gap sensor being provided on a magnetic bearing supporting a floating body in a non-contact manner by an electromagnetic force, the at least one gap sensor being configured to detect a gap between the floating body and a reference object that serves as a positional reference for position control of the floating body. The method includes: constructing a transformation formula for transforming an output of the at least one gap sensor into the gap using three or more constraints that are set as conditions for associating the gap with the output of the at least one gap sensor.

Magnetic levitation bearing structure includes a cylinder body, a rotating shaft, a motor stator, a motor rotor, an axial bearing, a radial bearing and a displacement sensing device; the displacement sensing device, the axial bearing stator, and the radial bearing stator are directly fixed on an inner wall of the cylinder body.

A tool includes a device including a housing and a rotor, the rotor to rotate about a longitudinal axis, and an axial gap generator including a stator assembly positioned adjacent to the rotor. The axial gap generator generates a voltage signal as a function of a gap spacing between the stator assembly and the rotor, the gap spacing being parallel to the longitudinal axis.

A bearing arrangement includes a shaft, at least one contact bearing and at least one non-contact bearing and a controller. The controller is configured to control a magnitude of a restoring force applied to the shaft by the non-contact bearing in accordance with a sensed parameter such that a stiffness of the shaft is modified such that one or more resonance frequencies of the shaft are moved away from one or more external forcing frequencies.

A discharge excitation gas laser device may include a laser chamber in which a laser gas containing a halogen gas is encapsulated, a pair of discharge electrodes disposed to face each other inside the laser chamber, a fan disposed inside the laser chamber to make the laser gas flow between the pair of discharge electrodes, a motor for rotating the fan, a motor power supply for supplying power to the motor, a magnetic bearing configured to levitate the rotary shaft of the fan magnetically, a displacement sensor for detecting the position of the rotary shaft through a can, and a controller configured to measure the rotational speed of the fan on the basis of a detection signal from the displacement sensor and control the motor power supply in such a manner that the measured rotational speed becomes a target rotational speed.