Controllers for controlling hybrid motor drive circuits configured to drive a motor are provided herein. A controller is configured to drive the motor using an inverter when a motor commanded frequency is not within a predetermined range of line input power frequencies, and couple line input power to an output of the inverter using a first switch device when the motor commanded frequency is within the predetermined range of line input power frequencies.

Controllers for controlling hybrid motor drive circuits configured to drive a motor are provided herein. A controller is configured to drive the motor using an inverter when a motor commanded frequency is not within a predetermined range of line input power frequencies, and couple line input power to an output of the inverter using a first switch device when the motor commanded frequency is within the predetermined range of line input power frequencies.

A system and method for supplying electric power to various pieces of fracturing equipment in a fracturing operation with gas powered generators. The system and method also includes switch gears, auxiliary trailers, transformers, power distribution panels, new receptacles, and cables to supply three-phase power to electric fracturing equipment. The switchgear in the power supply system is weatherproof and able to endure the wear and tear of mobilization. The novel system and method provide clean and quiet electricity to all the equipment on site.

A system and method for supplying electric power to various pieces of fracturing equipment in a fracturing operation with gas powered generators. The system and method also includes switch gears, auxiliary trailers, transformers, power distribution panels, new receptacles, and cables to supply three-phase power to electric fracturing equipment. The switchgear in the power supply system is weatherproof and able to endure the wear and tear of mobilization. The novel system and method provide clean and quiet electricity to all the equipment on site.

A system and method for supplying electric power to various pieces of fracturing equipment in a fracturing operation with gas powered generators. The system and method also includes switch gears, auxiliary trailers, transformers, power distribution panels, new receptacles, and cables to supply three-phase power to electric fracturing equipment. The switchgear in the power supply system is weatherproof and able to endure the wear and tear of mobilization. The novel system and method provide clean and quiet electricity to all the equipment on site.

A system and method for supplying electric power to various pieces of fracturing equipment in a fracturing operation with gas powered generators. The system and method also includes switch gears, auxiliary trailers, transformers, power distribution panels, new receptacles, and cables to supply three-phase power to electric fracturing equipment. The switchgear in the power supply system is weatherproof and able to endure the wear and tear of mobilization. The novel system and method provide clean and quiet electricity to all the equipment on site.

A random value integration unit 175 outputs a random value output from a random value generation unit 174 in a diffusion width Rand output from a diffusion width generation unit 173 by a product of an output of the random value generation unit 174 and an output of the diffusion width generation unit 173. A triangular wave signal generation unit 176 generates a triangular wave signal corresponding to a second carrier frequency fc2 which is obtained by adding the random value output from the random value integration unit 175 to a first carrier frequency fc1 which is an output of a carrier frequency setting unit 171. That is, a frequency obtained by increasing the diffusion width of the first carrier frequency fc1 is used as the second carrier frequency fc2, and the second carrier frequency is used as the carrier frequency.

A control circuit for a motor of a compressor includes an inverter control module configured to control power switching devices of an inverter to generate output voltages from a DC power supply. The output voltages are applied to windings of the motor. A current control module is configured to generate voltage signals based on a torque demand. The inverter control module controls the power switching devices according to the voltage signals. A selector is configured to output one of an open loop torque value and a closed loop torque value as the torque demand. An open loop torque module is configured to generate the open loop torque value. The open loop torque module is configured to apply an upper limit to the open loop torque value. The upper limit is based on a voltage of the DC power supply.

Disclosed herein is an apparatus for controlling an inverter. The apparatus determines the phase of an command voltage in a restart section taking into account the frequency of an input voltage to an electric motor when an input power is reduced below a rated power, the frequency of the input voltage into the electric motor at the time of restarting, a time period for generating a torque, and the phase of the input voltage to the electric motor at the time of the restarting.

An apparatus for restarting a medium voltage inverter is disclosed, wherein the medium voltage inverter can be restarted by estimating a rotor speed when an input power returns from an instantaneous defective state to a normal state, whereby a time to restart the medium voltage inverter can be reduced by a simple configuration to dispense with the need to wait until the rotor speed reaches zero speed.