A bearingless hub assembly comprising a rim hollowed to receive a tube magnet, and magnets embedded around the circumference of the rim on both ends. The rim is capped by front and rear rim plates configured to hold the embedded magnets in place and fitted to receive respective circular magnets. Similar magnets in corresponding front or rear drive plate maintain space (i.e., levitation) vis--vis the front and rear rim caps by repelling each other, thus allowing the rim (and, as applied, a mechanically-attached tire assembly) to move freely with no friction. The front and rear drive plate carry forward and reverse electromagnetic actuators as well as forward and reverse levitation control units, power generators and speed sensors. These components mount 360 degrees around the circumference of the drive plates while the embedded magnets of the rim spin through when in motion.

A position deviation calculated by a subtractor of a vacuum pump is input to the PIDs of three modes. The first PID is a PID controller for a high-bias mode, the second PID is a PID controller for a high-rigidity mode, and the third PID is a PID controller for a low-rigidity mode. The output signal of the third PID is extracted as a change of an indicator current for each clock of a PWM frequency and then the mean value of a change of an indicator current for several clocks is determined in a calculating unit. At this point, a switching control unit performs an operation on whether the mean value of the averaged change of the indicator current is larger than a preset redetermined value and then according to the result, an value is outputted in the range of 0 to 1 from the switching control unit.

A magnetic bearing (20) has: a rotor (22) to be supported for rotation about an axis (502); and a stator (24) extending from a first end (30) to a second end (32). The stator has: a circumferential outer winding (50); a circumferential inner winding (52); a radial spacing (54) between the inner winding and the outer winding; a plurality of laminate teeth (84A, 84B, 86A, 86B); and a plurality of radial windings (34A, 34B, 36A, 36B) respectively encircling a respective associated tooth of the plurality of teeth. A plurality of magnetic flux paths are respectively associated with the plurality of radial windings and pass: radially through the associated winding; axially through the radial spacing; radially from the radial spacing to the rotor; and axially along the rotor.

A control method for a magnetic bearing includes following steps: acquiring a suspension stopping instruction for the magnetic bearing, and respectively applying a control current to one or more control coils of the magnetic bearing to subject a rotor to a vertically or obliquely upwards electromagnetic force, a vertical component of the electromagnetic force is less than the gravity of the rotor. A control device for a magnetic bearing is also disclosed, including a suspension stopping instruction acquiring unit and a control current applying unit. The control method and control device for a magnetic bearing can control a falling velocity of the rotor to be lower than that of the rotor being subjected only to the gravity, and have higher control efficiency.

Disclosed is an air conditioner and a control method thereof, the air conditioner where a plurality of units is connected wirelessly to receive and transmit data with each other, and the control method in which an address is set in a wireless communication method using an initially set basic channel, a group is set in response to a response signal, and communication is performed with an indoor unit belonging into the same group through a new channel. Accordingly, the plurality of units in the air conditioner is able to receive and transmit data with each other wirelessly, and a group is set with respect to multiple units so that the multiple units are able to communicate with each other directly. Additionally, because a group is able to be easily set with respected to units connected via a pipe by setting a channel, it is possible to reduce a time for setting wireless communication and make the communication setting accurate. The present disclosure allows units to communicate using a different channel according to which group each unit belongs to, thereby preventing intervention between groups and malfunction of units.

A magnetic bearing control apparatus and a vacuum pump which do not require a displacement sensor, which enable control with high accuracy, and which are small and low cost. A rate of change (di/dt) that is a time derivative of a current value I.sub.m flowing through an electromagnet varies in accordance with a magnitude of a displacement of a gap between a target member and the electromagnet. The rate of change (di/dt) can be obtained by detecting a voltage value V.sub.s that is generated at both ends of an inductive element. Therefore, by detecting the voltage value V.sub.s, the magnitude of the displacement of the gap can be estimated by calculation. Inductive elements are connected in series to electromagnets and the voltage V.sub.s between the inductive elements is detected by the differential input amplifier. A single period of switching of a PWM switching amplifier is constituted by a current control period of the electromagnet and a displacement detection period for detecting the rate of change (di/dt). In addition, the displacement detection period is further constituted by a current increase period and a current decrease period which are certain periods of time. The current increase period and the current decrease period are equal to each other.

A first radial force value and a second radial force value is received by a radial magnetic bearing controller. Coefficients are computed for a first equation using the first and second radial force values. The first equation is solved to define first solution values. A second solution value paired with each first solution value is computed using the first radial force value and a respective first solution value to define second solution values. Control current sets are computed for each unique paired solution of the second solution values and the first solution values. Each control current set includes a control current value for each of three control currents. A control current value for each of the three control currents is selected from the control current sets. The control current value for each of the three control currents is output to a respective radial winding of a three-pole radial magnetic bearing.

The present disclosure provides a power supply system for a magnetic bearing and a control method therefor. The system includes a rectifying and filtering circuit configured to rectify and filter an alternating current to obtain a first direct current with a first DC bus voltage, the first direct current being configured to supply power to an electric motor controller of an electric motor to which the magnetic bearing belongs; a power obtaining circuit configured to obtain a second direct current with a second DC bus voltage from the first direct current, the second DC bus voltage being within an input voltage range allowed by the DC-DC power supply; a DC-DC power supply configured to convert the second direct current to a third direct current with a third DC bus voltage, the third direct current being configured to supply power to a bearing controller of the magnetic bearing.

A magnetic bearing device comprises a radial magnetic bearing configured to magnetically levitate and support a rotor shaft in a radial direction; an axial magnetic bearing configured to magnetically levitate and support, in an axial direction, a rotor disc rotatable together with the rotor shaft; and an axial displacement sensor disposed on a surface of an electromagnet core of the axial magnetic bearing facing the rotor disc and configured to detect axial displacement of the rotor disc.

The present disclosure relates to a chiller. A compressor driver includes: a compressor including a compressor motor and a magnetic bearing; a coil driver including a switching element and to apply a current to a bearing coil of the magnetic bearing by a switching operation of the switching element to cause a rotor of the compressor motor to be levitated from or land on the magnetic bearing; and a controller to control the switching element of the coil driver, wherein, when the rotor of the compressor motor lands, the controller is configured to gradually decrease the current flowing through the bearing coil. Accordingly, damage to the rotor of the compressor motor can be prevented when the compressor motor is stopped in a magnetic levitation system.