An electric motor drive device controls driving of a motor having open windings of two or more phases having end points that are open to each other. The switching arbitrator determines switching between a single-sided and dual-sided drive mode and arbitrates output of each of the inverters at a time of switching wherein output of the motor is continuous before and after the drive mode switching. The single-sided drive mode is a mode in which one of the two inverters performs switching drive. The dual-sided drive mode in which both the two inverters perform switching drive. The switching arbitrator gradually changes and increases the power level of the drive-start-side inverter from zero when the single-sided drive mode is switched to the dual-sided drive mode, and gradually changes and decreases the power level of the drive-end-side inverter to zero when the dual-sided drive mode is switched to the single-sided drive mode.

A method for starting a motor having a stator and a rotor is provided. The method includes starting a motor with field coils of the stator being in Y connection, switching the connection of the field coils to Δ connection when the speed of the rotor does not fall within a predetermined range from a rated speed within a predetermined time (t2), and switching the connection of the field coils to the Y connection when the speed of the rotor falls within the predetermined range from the rated speed.

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.

An apparatus for driving a motor of an MDPS may include: first to fourth driving power supply units configured to supply driving power to a driving motor; first to fourth inverters configured to switch the driving power supplied from the first to fourth driving power supply units, and supply the switched driving motor to the driving motor, in order to drive the driving motor; first to fourth driving units configured to drive the first to fourth inverters, respectively; a first control unit configured to operate the driving motor by switching the first and second inverters through the first and second driving units; a second control unit configured to operate the driving motor by switching the third and fourth inverters through the third and fourth driving units.

A driving device is used with a compressor including a motor including coils. The driving device drives the motor. The driving device includes an inverter connected to the coils, a connection switching unit to switch a connection state of the coils between a first connection state and a second connection state, a controller to control the inverter and the connection switching unit, and a compressor state detection unit to detect a state of the compressor. When the connection state of the coils is the first connection state, the controller controls the motor based on a first detection value detected by the compressor state detection unit and a first threshold. When the connection state of the coils is the second connection state, the controller controls the motor based on a second detection value detected by the compressor state detection unit and a second threshold.

A control device for a motor including a first coil and a second coil which are insulated from each other is provided. The control device includes a first circuit and a second circuit that switches a first process to a second process when the first circuit fails. The external circuit generates an instruction for performing a process of increasing an amount of operation which is calculated by one of the first circuit and the second circuit according to the number of control systems when the other of the first circuit and the second circuit fails.

One embodiment describes a wye-delta starter, which includes a first single pole, single current carrying path switching device that selectively connects and disconnects a first winding of a motor in a wye configuration; a second single pole, single current carrying path switching device that selectively connects and disconnects the first winding in a delta configuration, in which the first switching device and the second switching device are coupled via a first interlock; a third single pole, single current carrying path switching device that selectively connects and disconnects a second winding and a third winding of the motor in the wye configuration; a fourth single pole, single current carrying path switching device that selectively connects and disconnects the second winding in the delta configuration, in which the third switching device and the fourth switching device are coupled via a second interlock; and a fifth single pole, single current carrying path switching device that selectively connects and disconnects the third winding in the delta configuration.

One embodiment describes a wye-delta starter, which includes a first single pole, single current carrying path switching device that selectively connects and disconnects a first winding of a motor in a wye configuration; a second single pole, single current carrying path switching device that selectively connects and disconnects the first winding in a delta configuration, in which the first switching device and the second switching device are coupled via a first interlock; a third single pole, single current carrying path switching device that selectively connects and disconnects a second winding and a third winding of the motor in the wye configuration; a fourth single pole, single current carrying path switching device that selectively connects and disconnects the second winding in the delta configuration, in which the third switching device and the fourth switching device are coupled via a second interlock; and a fifth single pole, single current carrying path switching device that selectively connects and disconnects the third winding in the delta configuration.

One embodiment describes a motor starter, which includes a first single pole switching device that opens to disconnect power from a first winding of a motor; a second single pole switching device that closes after the first switching device opens to connect power to the first winding; a third single pole switching device closes after the second single pole switching device closes to increase power supplied to a second winding of the motor; a fourth single pole switching device that opens after the third single pole switching device closes to disconnect power supplied to a third winding of the motor and to reduce power supplied to the second winding; and a fifth single pole switching device that closes after the fourth switching device opens to connect power to the third winding.

One embodiment describes a motor starter, which includes a first single pole switching device that opens to disconnect power from a first winding of a motor; a second single pole switching device that closes after the first switching device opens to connect power to the first winding; a third single pole switching device closes after the second single pole switching device closes to increase power supplied to a second winding of the motor; a fourth single pole switching device that opens after the third single pole switching device closes to disconnect power supplied to a third winding of the motor and to reduce power supplied to the second winding; and a fifth single pole switching device that closes after the fourth switching device opens to connect power to the third winding.