A field of electric drive devices and electric machines, such as electric motors and electric generators for industrial applications, and more particularly to a method, an arrangement and a frequency converter for controlling lateral vibration of an electric machine. The arrangement of the present invention for controlling lateral vibration of an electric machine includes a frequency converter, one or more vibration sensors and an electric machine, wherein the one or more vibration sensors is/are arranged for measuring the lateral vibration from the electric machine and for producing measured vibration data; and wherein the frequency converter is arranged for generating a control torque for exerting the control torque on the stator of the electric machine, the control torque being determined utilizing the measured vibration data.

The invention relates to a method for determining an error voltage of a current converter to which a load, in particular in the form of a three-phase machine such as an asynchronous machine, is connected, is determined and if necessary compensated, wherein an output voltage on the current converter is increased stage-by-stage or step-by-step and which is measured here as a current adjusting a step response. The invention further relates to a three-phase machine, for example in the form of an asynchronous machine having power electronics comprising a current converter and in the form of a compensation device for compensating the error voltage of the current converter. The invention further relates to a method for operating and/or controlling such a three-phase machine, in which the error voltage of the current converter is determined and compensated. According to the invention, the error voltage is determined from the current measured as a step response and from a resistance of the load, wherein said resistance is determined from a target voltage jump and from a simultaneously measured actual current jump in a relatively high current range of at least 30% of at least 50% of the rated current of the end stage of the current converter.

The invention relates to a method for determining an error voltage of a current converter to which a load, in particular in the form of a three-phase machine such as an asynchronous machine, is connected, is determined and if necessary compensated, wherein an output voltage on the current converter is increased stage-by-stage or step-by-step and which is measured here as a current adjusting a step response. The invention further relates to a three-phase machine, for example in the form of an asynchronous machine having power electronics comprising a current converter and in the form of a compensation device for compensating the error voltage of the current converter. The invention further relates to a method for operating and/or controlling such a three-phase machine, in which the error voltage of the current converter is determined and compensated. According to the invention, the error voltage is determined from the current measured as a step response and from a resistance of the load, wherein said resistance is determined from a target voltage jump and from a simultaneously measured actual current jump in a relatively high current range of at least 30% of at least 50% of the rated current of the end stage of the current converter.

An electric motor system implements a redundant wye-wounded motor that includes first phase leads, second phase leads, first neutral leads, and second neutral leads. The first and second phase leads receive alternating current (AC) power from a power supply. A first phase-lead switch selectively connects the first phase leads to the power supply, and a second phase-lead switch selectively connects the second phase leads to the power supply. A first neutral-lead switch selectively connects the first neutral leads to the redundant wye-wounded motor, and a second neutral-lead switch selectively connects the second neutral leads to the redundant wye-wounded motor. A controller detects a circuit fault among a plurality of different types of circuit faults, and controls the operation of one or both of the primary neutral-lead switch and the second neutral-lead switch based on the circuit fault.

An electric motor system implements a redundant wye-wounded motor that includes first phase leads, second phase leads, first neutral leads, and second neutral leads. The first and second phase leads receive alternating current (AC) power from a power supply. A first phase-lead switch selectively connects the first phase leads to the power supply, and a second phase-lead switch selectively connects the second phase leads to the power supply. A first neutral-lead switch selectively connects the first neutral leads to the redundant wye-wounded motor, and a second neutral-lead switch selectively connects the second neutral leads to the redundant wye-wounded motor. A controller detects a circuit fault among a plurality of different types of circuit faults, and controls the operation of one or both of the primary neutral-lead switch and the second neutral-lead switch based on the circuit fault.

A method of controlling a 3n-phase electrical machine (7) by means of n power converters (3a, 3b) each being controlled by a respective controller, and each power converter (3a, 3b) being configured to power a respective set of three phases of the electrical machine (7), wherein the method for each controller comprises: a) obtaining measured currents (ia,1, ib,1, ic,1, ia,2, ib,2, ic,2) of the set of three phases of the electrical machine (7) controlled by the controller, b) estimating all currents ({circumflex over (.Math.)}dq, 2, {circumflex over (.Math.)}dq, 1) of all the other sets of three phases of the electrical machine (7), which are controlled by the other controllers, c) transforming the measured currents (ia,1, ib,1, ic,1, ia,2, ib,2, ic,2) and all the estimated currents ({circumflex over (.Math.)}dq,2, {circumflex over (.Math.)}dq,1) using vector space decomposition, VSD, to obtain a set of VSD currents, and d) controlling the corresponding power converter based on the VSD currents.

A motor controller comprises a switch circuit, a control unit, and a pulse width modulation signal, where the pulse width modulation signal has a duty cycle. The motor controller is used for driving a motor, where the motor has a coil. The switch circuit is configured to supply a coil current to the coil. The control unit is configured to generate a plurality of control signals to control the switch circuit. When the motor controller enters an early alignment state, the motor controller enables the coil current to achieve a predetermined value within one electric period. When the coil current achieves the predetermined value, the control unit records the duty cycle. The motor controller is configured to increase a success rate of starting the motor.

A motor controller comprises a switch circuit, a control unit, and a pulse width modulation signal, where the pulse width modulation signal has a duty cycle. The motor controller is used for driving a motor, where the motor has a coil. The switch circuit is configured to supply a coil current to the coil. The control unit is configured to generate a plurality of control signals to control the switch circuit. When the motor controller enters an early alignment state, the motor controller enables the coil current to achieve a predetermined value within one electric period. When the coil current achieves the predetermined value, the control unit records the duty cycle. The motor controller is configured to increase a success rate of starting the motor.

Embodiments of the present disclosure relate to a refrigeration system that includes a compressor configured to circulate refrigerant along a refrigerant loop, a motor configured to drive the compressor, and a variable speed drive coupled to the motor and configured to supply power to the motor. The variable speed drive includes a primary winding of a step down transformer coupled to an alternating current (AC) power source, a first secondary winding of the step down transformer, where the first secondary winding is configured to supply power at a variable supplied voltage to the motor when the motor operates below a threshold voltage, and a second secondary winding of the step down transformer, where the second secondary winding is configured to supply power at a fixed supplied voltage when the motor operates at or above the threshold voltage.

Embodiments of the present disclosure relate to a refrigeration system that includes a compressor configured to circulate refrigerant along a refrigerant loop, a motor configured to drive the compressor, and a variable speed drive coupled to the motor and configured to supply power to the motor. The variable speed drive includes a primary winding of a step down transformer coupled to an alternating current (AC) power source, a first secondary winding of the step down transformer, where the first secondary winding is configured to supply power at a variable supplied voltage to the motor when the motor operates below a threshold voltage, and a second secondary winding of the step down transformer, where the second secondary winding is configured to supply power at a fixed supplied voltage when the motor operates at or above the threshold voltage.