An apparatus for reducing noise of a gear pump through uneven pitch-simulated control includes a calculation unit to calculate different control current values for each tooth of a teeth order by applying a teeth number, the teeth order, and a teeth angle of the gear pump in which a plurality of teeth are evenly formed, a storage unit to map and store the teeth order and the different control current values corresponding to the teeth order for each tooth, and a current controller to variably generate the control current value mapped corresponding to the teeth order when each tooth reaches a reference position when the gear pump rotates by a motor, wherein the control current value is added to a reference current value of a motor control signal and applied to the motor.

A stator assembly includes a stator core defined by an inner periphery and an outer periphery, and a plurality of coils. The stator core includes a stator yoke. Each coil of the plurality of coils includes a first set of segments and a second set of segments each extending between the inner periphery and the outer periphery of the stator core. The first set of segments is arranged to form a first coil portion having a “V” shape and the second set of segments is arranged to form a second coil portion having a “V” shape. The first coil portion and the second coil portion each have a vertex and two ends. The ends of the first coil portion are coupled to the ends of the second coil portion. Other example stators, and example dynamoelectric machines and compressors including one or more stators are also disclosed.

A stator assembly includes a stator core defined by an inner periphery and an outer periphery, and a plurality of coils. The stator core includes a stator yoke. Each coil of the plurality of coils includes a first set of segments and a second set of segments each extending between the inner periphery and the outer periphery of the stator core. The first set of segments is arranged to form a first coil portion having a “V” shape and the second set of segments is arranged to form a second coil portion having a “V” shape. The first coil portion and the second coil portion each have a vertex and two ends. The ends of the first coil portion are coupled to the ends of the second coil portion. Other example stators, and example dynamoelectric machines and compressors including one or more stators are also disclosed.

A variable capacity screw compressor comprises a suction port, at least two screw rotors and a discharge port being configured in relation to a selected rotational speed that operates at least one screw rotor at an optimum peripheral velocity that is independent of a peripheral velocity of the at least one screw rotor at a synchronous motor rotational speed for a rated screw compressor capacity. A motor is configured to drive the at least one screw rotor at a rotational speed at a full-load capacity that is substantially greater than the synchronous motor rotational speed at the rated screw compressor capacity. A variable speed drive receives a command signal from a controller and generates a control signal that drives the motor at the selected rotational speed.

A variable capacity screw compressor comprises a suction port, at least two screw rotors and a discharge port being configured in relation to a selected rotational speed that operates at least one screw rotor at an optimum peripheral velocity that is independent of a peripheral velocity of the at least one screw rotor at a synchronous motor rotational speed for a rated screw compressor capacity. A motor is configured to drive the at least one screw rotor at a rotational speed at a full-load capacity that is substantially greater than the synchronous motor rotational speed at the rated screw compressor capacity. A variable speed drive receives a command signal from a controller and generates a control signal that drives the motor at the selected rotational speed.

A welding machine includes a welding power supply that generates a welding waveform during a welding operation, an internal combustion engine, and a generator that is operatively connected to the welding power supply to supply electrical energy to the welding power supply. The generator includes a rotor shaft driven by the internal combustion engine, and an end casting located at an end of the generator opposite the internal combustion engine. A rotary screw compressor is mounted to the end casting of the generator. A clutch mechanism couples the rotor shaft to the rotary screw compressor to selectively drive the rotary screw compressor by the rotor shaft.

In a method for operation control of a compressor, full-load running in which a gas intake control valve is fully open and a target rotation speed of a drive source is set to a full-load rotation speed that is a maximum rotation speed in a speed control band when pressure of compressed gas supplied to the consumption side is a datum pressure or less is carried out; then no-load running in which the valve is fully closed and a no-load rotation speed is set as the target rotation speed of the drive source when the supply pressure is a no-load running pressure or less that is a pressure higher than the datum pressure is carried out. The no-load running is started from the standard no-load rotation speed, however, after a transition time, the target rotation speed is reduced to a low speed no-load rotation speed.

In a method for operation control of a compressor, full-load running in which a gas intake control valve is fully open and a target rotation speed of a drive source is set to a full-load rotation speed that is a maximum rotation speed in a speed control band when pressure of compressed gas supplied to the consumption side is a datum pressure or less is carried out; then no-load running in which the valve is fully closed and a no-load rotation speed is set as the target rotation speed of the drive source when the supply pressure is a no-load running pressure or less that is a pressure higher than the datum pressure is carried out. The no-load running is started from the standard no-load rotation speed, however, after a transition time, the target rotation speed is reduced to a low speed no-load rotation speed.

A controller for a compressor, more specifically for a first electrical VSD motor configured to drive a compressor element, the controller including a housing in which is provided a rectifier, a DC link with a DC bus and two inverters connected to the same DC bus, a first inverter configured to control the first VSD motor driving the compressor element, and a second inverter configured to control a second VSD motor driving a fan configured to cool the compressor.

A controller for a compressor, more specifically for a first electrical VSD motor configured to drive a compressor element, the controller including a housing in which is provided a rectifier, a DC link with a DC bus and two inverters connected to the same DC bus, a first inverter configured to control the first VSD motor driving the compressor element, and a second inverter configured to control a second VSD motor driving a fan configured to cool the compressor.