An electric driven hydraulic fracking system is disclosed. A pump configuration that includes the single VFD, the single shaft electric motor, and the single hydraulic pump that is mounted on the single pump trailer. A pump configuration includes a single VFD configuration, the single shaft electric motor, and the single shaft hydraulic pump mounted on the single pump trailer. The single VFD configuration converts the electric power at the power generation voltage level distributed from the power distribution trailer to a VFD voltage level and drives the single shaft electric motor to control the operation of the single shaft electric motor and the single hydraulic pump. The VFD voltage level is a voltage level that is required to drive the single shaft electric motor. The VFD configuration also controls operation of the auxiliary systems based on the electric power at the auxiliary voltage level.

An electric motor system is described. The electric motor system includes a drive circuit including an inverter configured to supply variable frequency current and a contactor configured to supply line frequency current. The electric motor system also includes an electric motor coupled to the drive circuit wherein the electric motor is communicatively coupled to a controller. The controller is configured to control the inverter to supply variable frequency current to the electric motor, thereby operating the electric motor at a motor speed, and determine, based upon at least one input parameter, a maximum potential motor speed the inverter can achieve. The controller is also configured to receive a command to operate the electric motor at line frequency current and control the drive circuit to transition from supplying variable frequency current to supplying line frequency current before the maximum potential motor speed the inverter can achieve is reached.

The invention relates to a method for controlling a three-phase inverter (3) using a 120° control arrangement associated with a PWM-type control, the inverter (3) being driven by a controller and configured to power a permanent-magnet synchronous motor (5) of a device on board an aircraft. The motor (5) comprises a stator and a rotor that can be rotated relative to the stator when the motor (5) is powered. The inverter (3) comprises three branches (31, 32, 33), each branch comprising two switches (310, 311, 320, 321 and 330, 331) associated with a motor winding sing a 120° control arrangement of a three-phase inverter. The method is characterised in that when one switch on one branch is controlled such as to switch front the on-state to the off-state, the other switch on said branch is controlled such as to be in the on-state for a sufficient amount of time to allow the magnetic discharge of the motor winding associated with said branch.

A drive system includes: first and second inverters; a high-potential-side connection line; a low-potential-side connection line; a first changeover switch provided to at least one of the high-potential-side and low-potential side connection lines; a second changeover switch connected in parallel to the first changeover switch; a mode control section changing between a first mode in which to perform switching driving of upper and lower arm switches in one of the inverters and perform neutral point driving of at least one of the upper and lower arm switches in the other inverter to maintain in an on state and a second mode in which to perform switching driving of the upper and lower arm switches in both the inverters; and a changeover control section that, at the time of a changeover between the first and second modes, changes the first and second changeover switches between the on and off states.

Control of an AC motor includes rotation over an operating speed range with the output from an inverter by operating the inverter at switching frequencies that vary in proportion to rotor speed. The operating speed range is parsed into a plurality of speed regions and the switching frequencies within each operating speed region may correspond to a respective pulse ratio that is different from the respective pulse ratio corresponding to an adjacent speed region.

Control of an AC motor includes rotation over an operating speed range with the output from an inverter by operating the inverter at switching frequencies that vary in proportion to rotor speed. The operating speed range is parsed into a plurality of speed regions and the switching frequencies within each operating speed region may correspond to a respective pulse ratio that is different from the respective pulse ratio corresponding to an adjacent speed region.

Certain embodiments of the present application relate to a variable frequency drive (VFD) cabin for a pump configuration including a mobile trailer on which the VFD cabin is to be mounted. The VFD cabin generally includes a medium-voltage VFD and a ventilation system. In certain embodiments, the ventilation system is configured to generate an overpressure condition within the cabin to discourage the entry of dust and debris into the cabin. In certain embodiments, one or more components of the medium-voltage VFD are coupled to the floor of the cabin via a vibration damping system. In certain embodiments, the VFD cabin may be directly coupled to a chassis of the mobile trailer without an intervening suspension being provided between the VFD cabin and the chassis.

Certain embodiments of the present application relate to a variable frequency drive (VFD) cabin for a pump configuration including a mobile trailer on which the VFD cabin is to be mounted. The VFD cabin generally includes a medium-voltage VFD and a ventilation system. In certain embodiments, the ventilation system is configured to generate an overpressure condition within the cabin to discourage the entry of dust and debris into the cabin. In certain embodiments, one or more components of the medium-voltage VFD are coupled to the floor of the cabin via a vibration damping system. In certain embodiments, the VFD cabin may be directly coupled to a chassis of the mobile trailer without an intervening suspension being provided between the VFD cabin and the chassis.

A motor control method includes the following steps: receiving a frequency command and an excitation current setting value as a motor speed command; running a magnetic flux calculation program to generate a magnetic flux voltage command; generating a synchronous coordinate voltage command, and providing a three-phase current to a sensorless motor; calculating a synchronous coordinate feedback current based on the three-phase current, and calculating an effective current value of three-phase current; calculating a reactive power feedback value based on synchronous coordinate voltage command and the synchronous coordinate feedback current; running a steady state calculation program to calculate a reactive power command based on frequency command and the effective current value; calculating a reactive power error value between the reactive power command and the reactive power feedback value; and adding magnetic flux voltage command and reactive power error value to adjust synchronous coordinate voltage command and change three-phase current.

A common mode line-to-ground filter is disclosed which includes but is not limited to a resistor, capacitor and a ground. The common mode line to ground filter is connected on a high side of a step-up transformer. A low side of the step-up transformer is connected to a variable frequency drive that provides a semi-sinusoidal voltage waveform. The common mode line to ground filter generates a filtered sinusoidal waveform from the output of the step-up transformer. The filtered sinusoidal voltage waveform is supplied via an electrical cable to an electrically submersible pump deployed downhole.