A system for controlling a motor may include an alternating current (AC) bus configured to transmit an AC power signal to a set of stator windings, where the AC power signal produces a first rotating magnetic flux at the set of stator windings. The system may also include a high frequency contactless transformer configured to transmit an excitation signal to a set of rotor windings, where the excitation signal produces a second rotating magnetic flux at the rotor. The system may also include electrical circuitry configured to determine a rotor voltage and a rotor current associated with the excitation signal, determine a rotor flux magnitude estimate and a rotor flux angle estimate based on the rotor voltage and the rotor current, and determine an inverter control signal operable to generate the excitation signal based at least partially on the rotor flux magnitude estimate and the rotor flux angle estimate.

A generalized frequency conversion system for a steam turbine generator unit. The system comprises at least a variable speed steam turbine with an adjustable rotating speed, a water feeding pump, a variable frequency generator operating at a variable speed, a speed increasing gearbox with a fixed rotating speed ratio, a variable frequency bus and an auxiliary machine. With a change in load of the unit, parameters of steam entering the variable speed steam turbine and an extracted steam amount are adjusted (changed) accordingly, so that the rotating speed of the steam turbine changes accordingly. In this way, on one hand, the rotating speed of the water feeding pump is changed through the speed increasing gearbox; and on the other hand, the frequency of alternating current outputted by the variable frequency generator is changed. In the present invention, there is no need to additionally provide other types of frequency converters, and the system is simple, reliable, low in cost and high in efficiency.

Solar Motor Controller is an electronic device with DC power input terminals that may connect directly to solar PV panels, and output terminals that may connect directly to single or multiphase phase AC electric motors without requiring an energy storage subsystem. The Controller runs electric motors of many frequencies and is capable of interfacing to multiple voltages of solar PV panels with or without maximum power point tracking. The Controller may drive motors in water pumping, HVAC, refrigeration, compressors operation, blowers, machine tools, and many other applications; some controller applications may operate at motor speeds adjusted to conform to power available from attached solar panels.

A thyristor starter is configured to accelerate a synchronous machine from a stop state to a predetermined rotation speed by sequentially performing a first mode of performing commutation of an inverter by intermittently setting DC output current of a converter to zero and a second mode of performing commutation of the inverter by induced voltage of the synchronous machine. In a first case in which a first synchronous machine having a first inductance is started, a switching rotation speed for switching from the first mode to the second mode is set to a higher rotation speed, compared with a second case in which a second synchronous machine having a second inductance larger than the first inductance is started.

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.

The present disclosure is constructed on the prior art inverter architecture, a pulse code width modulation (PCWM). This is an open loop motor control system without sensing its rotor position. The present disclosure employs a closed loop method to track the optimum efficiency motor operating point directly. A bench load test is conducted to gather information for an AI type control, which includes both load angle vs. voltage command charts and power factor vs. voltage command charts, with load levels as parameters for certain frequency command ranges. This way, the optimum efficiency motor operating points are generated a priori. The AI type control is mechanized to track the optimum efficiency motor operating points.

A fan drive circuit for a variable speed fan motor in a cooling system, includes an inverter configured to supply a current signal to stator windings of the variable speed fan motor, a frequency detection circuit coupled to an output stage of an inverter of a compressor motor of the cooling system and configured to detect a first frequency of a compressor current signal at the output stage of a variable speed compressor drive circuit and generate a frequency signal, and a digital signal processor (DSP) coupled to the inverter and the frequency detection circuit. The DSP is configured to receive the frequency signal corresponding to the first frequency from the frequency detection circuit, select a second frequency corresponding to the first frequency at which to operate the variable speed fan motor, and transmit control signals to the inverter to supply current to the stator windings at the second frequency.

The present invention provides a method and system for controlling the temperature of an electric motor by adjusting the electric losses in the motor. In an embodiment, the required load on the motor is determined and a first motor voltage is provided to meet the required load. A predetermined temperature set point for the motor is compared against the temperature of the motor and based on the temperature of the motor and the predetermined temperature set point, a secondary motor voltage is determined. The motor voltage may then be adjusted based on the calculated voltage and the motor load measurement adjusted based on the measured motor speed and actual motor voltage.

In order to improve a method for selecting a frequency converter for a refrigerant compressor unit that includes a refrigerant compressor and an electric drive motor such that the frequency converter is selected in a manner for optimized use, it is proposed that a working state suitable for operation of the refrigerant compressor unit should be selected within an application field of an application graph of the refrigerant compressor, that an operating frequency for this selected working state should be selected, and that a working state operating current value that corresponds to the selected working state and the selected operating frequency should be determined from drive data, for operation of the refrigerant compressor unit.

A sensor is configured to sense current, of one or more output phases of an inverter, associated with back electromotive force (back EMF) of the machine. A converter or electronic data processor is adapted to convert the sensed current into current vectors associated with a stationary reference frame. An estimator or current model is configured to estimate back-EMF vectors from the converted current vectors. A vector tracking observer or the electronic data processor is adapted to mix the back-EMF vectors and applying the mixed back-EMF vectors to a preliminary inertial model. A secondary observer or the data processor is operable to apply the output of the preliminary inertial model to a secondary inertial model in the second speed range to estimate position or motion data for the rotor.