An electromagnetic rotary drive includes a magnetically contactlessly drivable rotor free of coils, and a stator configured as a bearing and drive stator configured to drive the rotor magnetically and contactlessly about an axis of rotation. The rotor is capable of being supported magnetically contactlessly with respect to the stator in an operating state. The stator includes an upper stator part having a plurality of pronounced upper poles configured to carry upper windings and a lower stator part having a plurality of pronounced lower poles configured to carry lower windings. The upper stator part and the lower stator part are arranged spaced apart from one another with respect to an axial direction. A permanent magnet is disposed between the upper stator part and the lower stator part.

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 generator assembly for harvesting energy in a bearing arrangement having a first ring and a second ring is provided. The generator assembly includes a plurality of coils attached to the first ring and configured to interact with a magnet ring with alternating magnetization directions attached to the second ring, and a plug connector for supplying power generated by the generator assembly to external devices. The coils are encapsulated and mounted in an outer carrier ring such that the winding axis is oriented in a radial direction of the bearing and the magnet ring is composed of plural permanent magnets attached to an inner carrier ring attached to the inner ring of the bearing.

A generator assembly for harvesting energy in a bearing arrangement having a first ring and a second ring is provided. The generator assembly includes a plurality of coils attached to the first ring and configured to interact with a magnet ring with alternating magnetization directions attached to the second ring, and a plug connector for supplying power generated by the generator assembly to external devices. The first ring is an outer ring of the bearing, the groove is formed on an outer circumference of the first ring and is helicoidally shaped, and a helix angle of the groove is 45 or more.

Unique systems, methods, techniques and apparatuses of power amplifiers are disclosed. One exemplary embodiment is a power system for an active magnetic bearing including at least one power amplifier. Each power amplifier includes a first semiconductor device including a first node coupled to a neutral point node and a second node, a second output node coupled to the neutral point node, a second semiconductor device including a first node coupled to the second node of the first semiconductor device and a second node coupled to a first output node, a third semiconductor device including a first node coupled to a first DC bus node and a second node coupled to the first output node, and a fourth semiconductor device including a first node coupled to a second DC bus node and a second node coupled to the second node of the first semiconductor device.

A balanced switching amplifier for a magnetic bearing assembly may include a first switching amplifier configured to drive a first load of an electromagnet of the magnetic bearing assembly via a first plurality of lead wires. The balanced switching amplifier may also include a second switching amplifier configured to drive a second load of the electromagnet via a second plurality of lead wires. The first switching amplifier and the second switching amplifier may be configured to operate in tandem such that respective voltages in the first plurality of lead wires and the second plurality of lead wires substantially neutralize one another, thereby reducing electromagnetic emissions from each of the first plurality of lead wires and the second plurality of lead wires.

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.

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.

A magnetic bearing device for magnetically suspending a rotor (22) for rotation about a rotation axis (A) comprises an amplifier device, a first main coil (p) and a second main coil (n). In order to compensate for a stray flux that is created when the main coils are supplied with currents from the amplifier device, a compensation coil (c) is connected between a common node of the main coils and the amplifier device with such polarity that a current flowing through the compensation coil will diminish the stray flux caused by the main coils (p, n).