Embodiments of a mixing device power system generally include a power control module, an AC motor, and a variable frequency drive, wherein upon application of AC power to the system, electrical power is provided to the power control module which transmits electrical power to the AC motor, whereby rotation of a mixing spindle is initiated. After the spindle has begun rotating, transmission of electrical power from the power control module to the AC motor is ceased, and substantially simultaneously electrical power transmission is commenced from the power control module to the variable frequency drive which transmits electrical power to the AC motor, whereby rotation of the mixing spindle is continued. A method of using the mixing device power system to mix a fluid sample is also provided.

A system for controlling an AC motor is provided. The system comprises an electrical connection path for connecting an electrical input of the AC motor to a first phase of alternating current from an electric power supply. The system also comprises two or more motor controllers, each motor controller is located on the electrical connection path between the electric power supply and the AC motor and is operable to regulate current of the first phase passing through it. Each motor controller is connected in parallel, relative to the other motor controllers, to the electrical connection path. At least one processor is configured to control the motor controllers to repeatedly change which of the motor controllers current of the first phase passes through, such that at any given time current of the first phase only passes through one of the motor controllers. A corresponding method is also provided.

A compressor driving apparatus, or a home appliance including the same, includes a DC terminal capacitor to store a charge, an inverter to convert direct current associated with the charge of the DC terminal capacitor into an alternating current and output the alternating current to a motor, an output current detection unit to detect an output current flowing in the motor, and an inverter controller to increase a motor speed by starting the motor, and controlling a speed increase of the motor to change based on an increasing slope of a change in an output current detected by the output current detection unit during the speed increase of the motor.

This method for controlling an asynchronous electrical motor (32) of a compressor system (10), comprises:connecting (100) a capacitor bank (50) of the compressor system (10) in parallel with a first electrical motor (32) of the compressor system, this connection comprising connecting capacitors (52, 54, 56) of the capacitor bank (50) to windings of the stator of the first motor (32), by operating a switch unit (60) of the capacitor bank connected to an internal power bus (12);starting (102) the first asynchronous electrical motor (32), by providing an input electrical current to the windings of the first motor (32) from the internal power bus (12);disconnecting (108) the capacitor bank (50) from said first motor (32) once said motor (32) has started, this disconnection comprising disconnecting said capacitors (52, 54, 56) from the windings of the motor (32).

This method for controlling an asynchronous electrical motor (32) of a compressor system (10), comprises:connecting (100) a capacitor bank (50) of the compressor system (10) in parallel with a first electrical motor (32) of the compressor system, this connection comprising connecting capacitors (52, 54, 56) of the capacitor bank (50) to windings of the stator of the first motor (32), by operating a switch unit (60) of the capacitor bank connected to an internal power bus (12);starting (102) the first asynchronous electrical motor (32), by providing an input electrical current to the windings of the first motor (32) from the internal power bus (12);disconnecting (108) the capacitor bank (50) from said first motor (32) once said motor (32) has started, this disconnection comprising disconnecting said capacitors (52, 54, 56) from the windings of the motor (32).

This method for controlling asynchronous electrical motors of a compressor system, comprises: receiving an order to start a first asynchronous electrical motor and a second asynchronous electrical motor of a compressor system; unloading said first and second motors, by operating respectively a first load control unit of the first motor and a second load control unit of the second motor, in order to reduce the mechanical load associated to said motors; starting the first motor and, only once the first motor is running at nominal speed, starting the second motor, loading both the first and second electrical motor only once the second motor has started and is running at nominal speed, by operating the first load control unit and the second load control unit, in order to increase the mechanical load associated to said motors.

This method for controlling asynchronous electrical motors of a compressor system, comprises: receiving an order to start a first asynchronous electrical motor and a second asynchronous electrical motor of a compressor system; unloading said first and second motors, by operating respectively a first load control unit of the first motor and a second load control unit of the second motor, in order to reduce the mechanical load associated to said motors; starting the first motor and, only once the first motor is running at nominal speed, starting the second motor, loading both the first and second electrical motor only once the second motor has started and is running at nominal speed, by operating the first load control unit and the second load control unit, in order to increase the mechanical load associated to said motors.

A reactive power system comprises a plurality of electrical capacitor banks, with each electrical capacitor bank electrically connected in series with an electrical switch. The electrical switches may be electrically connected to a system such as, for example, an electrical induction motor starter system. A controller is coupled with the motor starter system and each of the electrical switches. The controller, in response to receiving a signal from the motor starter system, determines which of the plurality of electrical capacitor banks from which electrical power should be provided for the motor starter system. For the determined or identified electrical capacitor bank(s), the controller identifies the corresponding electrical switch(es) and communicates a signal to close the switch(es). Closing the switches results in the capacitors in the corresponding electrical capacitor banks to be electrically connected to the motor starter system and to provide current to the motor starter system.

A vehicle includes an engine, an electric machine, and a controller. The electric machine is configured to start the engine. The controller is programmed to pre-flux the electric machine with current that has a magnitude that changes as temperature of the engine changes within a predefined range.

The present invention provides an improved hybrid motor starter that extends the expected life of the main motor contacts of a standard contactor by reducing arcing during opening and closing of the main motor contacts and permits the use of physically smaller solid state switching devices and secondary contacts that have electrical ratings significantly lower than the standard contactor. The use of smaller solid state switching device and secondary contacts that have lower electrical ratings is permitted by minimizing the time at which these devices are exposed to full motor currents.