An estimation method for estimating a rotor frequency of a motor during freewheeling, includes: applying a fixed input voltage and one selected from a plurality of stator frequencies to the motor sequentially so as to perform frequency scanning; detecting a stator current value of the motor corresponding to the selected stator frequency; calculating a stator current slope of the stator current values sequentially; defining a target period from a start point where the stator current slope varies from positive to negative to an end point where the stator current slope varies from negative to positive; and determining that a difference between the scanned stator frequency and the rotor frequency is within a preset value, then designating any of the corresponding stator frequencies during the target period as an estimated value of the rotor frequency.

A method includes configuring a motor drive system with a motor/generator and a plurality of inverters coupled to the motor/generator, configuring a plurality of active harmonic planes to generate a torque on each of the active harmonic planes, and applying a harmonic plane synchronization mechanism to the plurality of active harmonic planes so that torque components and magnetizing components of currents are controlled in coordination on different active harmonic planes to output a desired torque from the motor/generator.

An example power delivery device includes a drive shaft to connect with a load, a first motor connected with the drive shaft through a first reducer, and at least one second motor connected with the drive shaft through a second reducer, wherein a first final driven gear of the first reducer is directly connected with the drive shaft, and a second final driven gear of the second reducer is connected with the drive shaft through a one-direction connector.

Disclosed are an inverter control device and method. The method according to an embodiment of the present includes estimating a rotation speed of a motor, determining a slip frequency reference using an energy of a direct current terminal capacitor of an inverter, which provides an output voltage to the motor, and a direct current terminal energy reference when a direct current terminal voltage of the inverter is a certain level or less, and providing a frequency reference determined by adding the rotation speed of the motor and the slip frequency reference to the inverter.

A system for controlling an operation of an induction motor (IM). A controller processor detects a spectrum of a current signal from received sensor data using a module. Obtain a number of rotor bars and a number of pole pairs of the IM to identify a principle slot harmonics (PSH) type IM from stored IM data. Use the PSH-type IM to identify a static eccentricity (SE) fault signature signal located at a secondary PSH frequency of the PSH-type IM. Determine a level of signal strength in the spectrum of the current signal at a location of the secondary PSH frequency, and compare to a SE fault table database to obtain a SE fault level of the PSH-type IM. Compare the SE fault level to a database to obtain a SE fault threshold, and if the SE fault level is outside the SE threshold, generate an interrupt command to the controller.

A method is for operating a three-phase cage motor on a multiphase electrical grid via a soft starter, with which one or more grid phases of the grid being respectively switchable by firing thyristors. Apart from a grid-related firing criterion, a rotor-flux-related firing criterion is taken into account.

According to some embodiments, AC chopping circuit includes a switching circuit, a synchronizing signal generating circuit, a switch driving circuit and an auxiliary power supplying circuit. In some examples, the switching circuit are coupled to an AC power source and a load. In certain examples, the synchronizing signal generating circuit provides a synchronizing signal which is related to a polarity of the AC power source. In some examples, the switching circuit is controlled based at least in part on the synchronizing signal.

Provided is a power conversion controller in which variation in reactive power among power conversion controllers can be inhibited while maintaining the running performance of vehicles. The power conversion controller includes a power factor setter that sets a power factor based on a detection value of an overhead line voltage, and a calculator that calculates a reactive current command value by multiplying an active current command value by a tangent of a power factor angle of the power factor. The power factor setter sets a reference value set in advance as the power factor if the detection value is within a reference range, sets a value smaller than the reference value as the power factor if the detection value is below the reference range, and sets a value larger than the reference value as the power factor if the detection value is beyond the reference range.

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.

A motor control system includes a multi-phase motor, a multi-phase inverter circuit, a plurality of controllable switches, a plurality of sensors, and a monitor circuit. Each controllable switch is coupled in series between a second terminal of the motor and a common winding node and is responsive to switch commands to operate in either a first switch mode or a second switch mode. The monitor circuit is responsive to sensor signals to determine when one or more of the sensed motor state variables attains a predetermined threshold magnitude and when one or more of the sensed motor state variables attains the predetermined threshold magnitude, to supply a switch command to one or more of the controllable switches that causes the one or more controllable switches to operate in the second switch mode.