Capacitor balancing of a dual three-level (3L) T-type converter based on silicon carbide (SiC) discrete semiconductors was performed with the converter feeding an open-ends induction motor (OEIM). A model predictive control (MPC) using a two step cost function calculation was developed to balance the DC link capacitors and control the machine torque simultaneously. The number of redundant switching states used was reduced without affecting the operating voltage vectors, which substantially reduced the computational time. A simulation and experimental results are in good agreement.

An electronic control unit includes calculating a slip frequency of a rotating electric machine from a torque instruction value to the rotating electric machine and a target value of output efficiency to the rotating electric machine, calculating a frequency of the instruction signal from the slip frequency and a rotational frequency of the rotating electric machine, the slip frequency being changed by changing the target value of the output efficiency with the torque instruction value maintained and changing the slip frequency so as to change the frequency of the instruction signal to out of an inverter lock frequency band when the frequency of the instruction signal is included in the inverter lock frequency band.

In a method for determining the rotor position of a three-phase machine without using a rotary encoder, and to a device for controlling a three-phase motor without using a rotary encoder, the three-phase machine is fed by a converter that can be operated by pulse-width modulation, and the converter has model variables for the rotor angle and the current indicator of the three-phase machine, and the converter has device(s) by using which, in control operation, at least two values are measured which represent a measure of the local inductances of the machine which represent a measure of the local inductances of the machine, the error of the model rotor angle is determined in that, depending on the model rotor angle and the model current indicator, at least two weighting factors are determined, and in that a weighted sum is formed from the at least two measured values and the at least two weighting factors, and in that a further offset value is substracted from the sum, which is likewise determined on the basis of the model rotor angle and the model current indicator.

A motor drive device: a power conversion unit; a current detection unit that detects a phase current of the alternating-current motor; a position/speed specifying unit that specifies a magnetic pole position and a rotational speed of the alternating-current motor; a d-axis current pulsation generating unit that generates a d-axis current pulsation command based on q-axis current pulsation or a q-axis current pulsation command, which being in synchronization with the q-axis current pulsation or the q-axis current pulsation command and preventing or reducing an increase or decrease in amplitude of the voltage command; and a dq-axis current control unit that generates the voltage command for controlling the phase current on the dq rotating coordinates, which rotate in synchronization with the magnetic pole position, by using the magnetic pole position, the rotational speed, the phase current, the q-axis current pulsation or the q-axis current pulsation command, and the d-axis current pulsation command.

There is provided a device for correcting a Hall sensor installation position error in a BLDC motor which includes a rotor with a permanent magnet, a stator wound with coils to form a magnetic field around the rotor, and three linear Hall sensors installed outwardly around the rotor to generate output signals by the Hall-Effect, the device comprising: a detection unit to detect output signals H.sub.1, H.sub.2, H.sub.3 output from the three linear Hall sensors; a transformation unit to transform the output signals H.sub.1, H.sub.2, H.sub.3 detected in the detection unit to orthogonal two-phase transformation signals H.sub.a, H.sub.b and to transform the transformation signals H.sub.a, H.sub.b to normalized transformation signals H.sub.an, H.sub.bn; an operation unit to calculate a rotation angle of the motor from the normalized transformation signals H.sub.an, H.sub.bn output in the transformation unit; and a control unit to control the current supplied to the coils winding the stator based on information of the rotation angle transmitted from the operation unit, wherein the transformation unit transforms the output signals H.sub.1, H.sub.2, H.sub.3 to the orthogonal two-phase transformation signals H.sub.a, H.sub.b by Clarke Transformation.

Reduced computation time for model predictive control (MPC) of a five level dual T-type drive considering the DC link capacitor balancing, the common-mode voltage (CMV) along with torque control of an open-ends induction motor based on determining a reduced set of switching states for the MPC. The reduced set of switching states are determined by considering either CMV reduction (CMVR) or CMV elimination (CMVE). Cost function minimization generates a voltage vector, which is used to produce gating signals for the converter switches. The reduced switching state MPC significantly reduces computation time and improves MPC performance.

The invention relates to a motor control device for controlling a motor current, with a predictive deadbeat control unit configured to, based on a motor current error input signal, use a model predictive control scheme for providing an output signal for controlling the motor current according to a deadbeat control scheme, where the deadbeat control scheme is characterized by minimizing the motor current error input signal within a preset time period; an interface unit configured to allow adjusting the preset time period by a user input; and an integrator unit configured to, based on the motor current error input signal, provide an integrator output that is added to the output signal for controlling the motor current with controlling a motor current, with the advantages of a predictive deadbeat control scheme while avoiding the problems present in the conventional predictive deadbeat approaches. The invention also relates to a corresponding method.

A method and device for acquiring a rotor position based on a permanent magnet synchronous drive system. The permanent magnet synchronous drive system includes an inverter and a permanent magnet synchronous motor, wherein the initial speed of the permanent magnet synchronous motor is not zero. The method includes: controlling a bridge arm switch of an inverter periodically; collecting a three-phase current of the permanent magnet synchronous motor at a fixed time within each control period; and after the three-phase current is reversed, sending same to a phase-locked loop system to conduct processing, so as to obtain a phase angle of an induction potential vector, and according to the phase angle of the induction potential vector, acquiring a rotor position angle of the permanent magnet synchronous motor.

A hydraulic fracturing system for fracturing a subterranean formation is disclosed. In an embodiment, the system can include a plurality of electric pumps fluidly connected to a well associated with the subterranean formation and powered by at least one electric motor, and configured to pump fluid into a wellbore associated with the well at a high pressure; at least one generator electrically coupled to the plurality of electric pumps so as to generate electricity for use by the plurality of electric pumps; a gas compression system fluidly coupled to the at least one generator so as to provide fuel for use by the at least one generator; and a combustible fuel vaporization system gaseously coupled to the gas compression system so as to provide at least one of vaporized fuel or gasified fuel, or a combination thereof, to the gas compression system.

A hydraulic fracturing system for fracturing a subterranean formation is disclosed. In an embodiment, the system can include a plurality of electric pumps fluidly connected to a well associated with the subterranean formation and powered by at least one electric motor, and configured to pump fluid into a wellbore associated with the well at a high pressure; at least one generator electrically coupled to the plurality of electric pumps so as to generate electricity for use by the plurality of electric pumps; a gas compression system fluidly coupled to the at least one generator so as to provide fuel for use by the at least one generator; and a combustible fuel vaporization system gaseously coupled to the gas compression system so as to provide at least one of vaporized fuel or gasified fuel, or a combination thereof, to the gas compression system.