A multiple drive for a heavy load application includes a plurality of drive trains which are activated such that individual ones of the plurality of drive trains are successively activated automatically during startup of the heavy load application as part of a predefined activation strategy according to a predefined activation scheme and an activation sequence defined therein. In the event of a repeated start of the heavy-load application, a different activation scheme can be used for the activation.

A device (1) for starting a motor (4) for alternating current, in particular for a compressor (5), wherein the motor (4) has at least one feed line (3) for the electrical power supply. The device comprises an actuator element (10) for limiting the current in the feed line (3), a switching element (16) for bypassing the actuator element (10), a current-monitoring element (15) for monitoring the current in the feed line (3), and a controller (18) for controlling the switching element (16). The actuator element (10) comprises at least a first start-up element (11) and a second start-up element (12) as well as a switch-over element (14) for switching over between the at least first and second start-up elements (11, 12).

A device (1) for starting a motor (4) for alternating current, in particular for a compressor (5), wherein the motor (4) has at least one feed line (3) for the electrical power supply. The device comprises an actuator element (10) for limiting the current in the feed line (3), a switching element (16) for bypassing the actuator element (10), a current-monitoring element (15) for monitoring the current in the feed line (3), and a controller (18) for controlling the switching element (16). The actuator element (10) comprises at least a first start-up element (11) and a second start-up element (12) as well as a switch-over element (14) for switching over between the at least first and second start-up elements (11, 12).

A starting method of a variable speed accelerator, which includes an electric device for generating rotational driving force and a transmission device for changing a speed of the rotational driving force generated by the electric device and transmits the changed rotational driving force to an object to be driven, the starting method includes: a constant speed electric motor starting step of starting a constant speed electric motor and gradually increasing a number of rotations in a first direction of a constant speed rotor and an internal gear; and a generator mode operating step of operating a variable speed electric motor in a generator mode and rotating a planetary gear carrier in the first direction, wherein the transmission device is a planetary gear transmission device, and wherein the electric device comprises: the constant speed electric motor.

A system includes a variable frequency drive (VFD) comprising an inverter having an output configured to be coupled to a motor and a switch configured to couple a power source to the motor to bypass the VFD. The system further includes a control circuit configured to synchronize the VFD to the power source, to operate the switch to couple the power source and the VFD in parallel and to subsequently disable the inverter responsive to a current of the inverter. In some embodiments, a PWM frequency of the VFD may be temporarily increased when transferring the motor from the power source to the VFD.

A motor control device is configured to drive a first motor that rotates a first rotation body and a second motor that rotates a second rotation body. The motor control device includes a power supply unit, inverters configured to convert an output from the power supply unit to an alternating current and supply the output to the first motor and the second motor, and a control unit configured to drive the second motor using rotor position sensorless control. The control unit may be configured to not start up the second motor during a predetermined operation in which a large current flowing through the first motor is being performed.

A motor control device is configured to drive a first motor that rotates a first rotation body and a second motor that rotates a second rotation body. The motor control device includes a power supply unit, inverters configured to convert an output from the power supply unit to an alternating current and supply the output to the first motor and the second motor, and a control unit configured to drive the second motor using rotor position sensorless control. The control unit may be configured to not start up the second motor during a predetermined operation in which a large current flowing through the first motor is being performed.

An electric propulsion system is described that includes an AC drive circuit, a synchronization circuit, and a control unit. The AC drive circuit includes a plurality of propulsor motors, an AC power bus, and an AC generator that delivers AC electrical power to the AC power bus for simultaneously driving the plurality of propulsor motors. The synchronization circuit is configured to synchronize, with the AC generator, single propulsor motor from the plurality of propulsor motors, at a time. The control unit is configured to maintain synchronicity between the single propulsor motor and the AC generator by engaging the synchronization circuit with the single propulsor motor in response to determining that the single propulsor motor is not synchronized with the AC generator.

A load starting system in which an upstream controller determines the sequence and timing for starting a group of loads in the most efficient and timely manner. The sequence and timing is determined by one or more real-time operational characteristics, device rating characteristics, customer/user characteristics or learned/historic characteristics or by a combination of the one or more real-time, device rating, customer/user or learned/historic characteristic.

A load starting system in which an upstream controller determines the sequence and timing for starting a group of loads in the most efficient and timely manner. The sequence and timing is determined by one or more real-time operational characteristics, device rating characteristics, customer/user characteristics or learned/historic characteristics or by a combination of the one or more real-time, device rating, customer/user or learned/historic characteristic.