A vacuum pump with dynamic control of cooling fan speed and motor flux is provided to reduce transmitted noise and waste heat and provide a quieter, more efficient pump.

This compressor system is provided with: a driving machine having a rotary-driven first output shaft and a second shaft that is rotary driven so as to reach the same speed as the first output shaft; a working-fluid-compressing first compressor to which the rotation of the first output shaft is transmitted; a working-fluid-compressing second compressor to which the rotation of the second output shaft is transmitted; a variable-speed step-up gear for increasing the speed of the first output shaft and transmitting the increased speed to the first compressor, said step-up gear being capable of varying the increased speed; and a constant-speed step-up gear for increasing the speed of the second output shaft and transmitting the increased speed to the second compressor, said step-up gear keeping the increased speed constant.

A power conversion apparatus includes: an inverter to drive a motor, using a first carrier signal; an inverter connected in parallel to the inverter, to drive a motor, using a second carrier signal; respective phase lower arm shunt resistors to detect a first current flowing inside the inverter; respective phase lower arm shunt resistors to detect a second current flowing in the inverter; and a control unit to control the inverters. A phase difference is set between the first carrier signal and the second carrier signal to prevent a detection period for the first current in the first carrier signal and a detection period for the second current in the second carrier signal from overlapping each other when the inverters are controlled.

Generally, a variable fan speed control in an HVAC system is described. Such methods and systems to control fan speed can in turn improve efficiency of the HVAC system by minimizing power consumption, for example of the compressor. The control scheme is based on various operating conditions of compressor load and ambient air temperature, which are used to determine an optimum fan speed.

A motor controller comprises: a rotation angle estimation unit for estimating and computing a rotation angle of a motor repeatedly based on the current and voltage of the motor without using a motor rotation angle detector; a speed calculation unit for calculating the period of the signal waveform of the rotation angle that is repeatedly estimated and calculated by the rotation angle estimation unit and for calculating an actual rotational speed of the motor based on the period; a drive signal generating unit for generating a drive signal to drive and control the motor based on at least a deviation between the actual rotational speed and a target rotational speed and the rotation angle; and a switching circuit that is switched based on the drive signal to provide drive power to the motor.

System and method for testing a pump. The testing of the pump includes determining a Mechanical Power Index (MPI) for the pump. The MPI is determined by operating the pump at operating speed for a minimum operating interval. When the pump is stopped under normal operation by the application, the pump speed is continuously monitored. The time when the pump speed decreases to an initial speed close to the operating speed is read as an initial time. When the pump speed decreases to a final pump speed close to the critical speed, the end time is read and the elapsed time is determined as Δt=end time−initial time. The MPI is calculated to be the initial pump speed minus the final pump speed divided by Δt. The MPI can be used during the lifetime of the pump to determine when the pump is deteriorating.

Systems, apparatus and methods for operating a chiller plant while minimizing or eliminating the occurrence of centrifugal compressor surge. Taking into account chiller design specifications and current operating conditions, a compressor lift point at which surge is predicted to occur is established. Minima and maxima for various chiller setpoints that avoid or eliminate the occurrence of compressor surge are imposed on setpoints provided by a conventional optimizing chiller controller. The chiller system is operated in accordance with the resultant anti-surge setpoints. Coolant tower flow is modulated to enable the compressor to operate at near-surge conditions while preventing the onset of actual surge.

At timing t0, a brake gas (raw material gas) starts to be supplied to an ion beam generator, and the brake gas is fed into a turbo molecular pump. After timing t1, a vent valve is opened intermittently to feed atmospheric air into the turbo molecular pump. The brake gas may be different from the raw material gas. The brake gas is supplied using a gas supply system.

A guide vane within an annular inlet duct of a gas-turbine engine provides for generating swirl within an annular inlet duct so as to provide for reducing the rate of deceleration of the inlet air flow within the annular inlet duct while providing for diffusion of the meridional component of velocity thereof.

A motor drive and method to control a motor in a fluid system. The method may comprise determining a pressure; determining a proportional error as a limited difference between the pressure and a pressure setpoint; determining an integral step as a limited proportional error; determining an integral error as a limited sum of the integral step and a preceding unbound integral error; determining an error as the product of the integral error, the proportional error, and a gain factor; and generating a control signal to cause the inverter to output a motor voltage to drive the motor and maintain the pressure about the pressure setpoint.