A method for detecting a stall condition of an electric motor. The method can include initiating an open-loop phase. During the open-loop phase, the method can include increasing a rotational speed of an electric motor and obtaining data indicative of a voltage associated with the electric motor while increasing the rotational speed of the electric motor. During the open-loop phase, the method can also include determining a difference between the voltage and a time varying target voltage and detecting a stall condition based at least in part on the difference between the voltage and the time varying target voltage. When a closed-loop condition is satisfied, the method can include initiating a closed-loop phase.

A motor controller 100-1 includes an inverter, a current detection unit, a current detector, and a PWM signal generator. Upon occurrence of a condition in which a first energization time period, which has an energization width in which a phase current for a first phase is detectable by the current detector, and a second energization time period, which has an energization width in which a phase current for a second phase is difficult to be detected by the current detector, are present, the PWM signal generator extracts a portion of a zero vector period for a first PWM signal, a second PWM signal, and a third PWM signal, to assign an energization width corresponding to the extracted zero vector period, to a period, other than the zero vector period, for a given PWM signal among the first PWM signal, the second PWM signal, and the third PWM signal, so that the second energization time period is adjusted to have an energization width in which the phase current for the second phase is detectable by the current detector.

A motor drive comprises a rectifier circuit portion arranged to receive an externally supplied AC voltage and to generate a DC bus voltage. An inverter circuit portion is arranged to receive the DC bus voltage (V.sub.DC_Bus) and to generate an AC output voltage (V.sub.out) for supply to an external load. A DC bus portion is connected between the rectifier and the inverter. An inductor (L.sub.1) is connected in series along a bus conductor between the rectifier and inverter, and a DC link capacitor (C.sub.1) is connected in parallel between the bus conductors. A voltage across the DC link capacitor (C.sub.1) is input to a tuneable notch filter arranged to supply a filtered signal. A controller varies the resonant frequency of the notch filter to a plurality of values across an operational range and modulates a supply current provided by the inverter with a probe current signal at the resonant frequency.

The present disclosure provides a power conversion apparatus converting a power from a DC power source, supplying the converted power to a rotary electric machine to drive the rotary electric machine. The power conversion apparatus according to the present disclosure includes: a first inverter circuit electrically connected to a first end of each of phase winding, transmitting power between respective phase windings and the DC power source; a second inverter circuit electrically connected to a second end each of phase winding, transmitting power between respective phase windings and the DC power source; and a control unit controlling the first inverter circuit and the second inverter circuit. The control unit is configured to change a total amount of current flowing through respective phase windings depending on a rotational speed of the rotary electric machine.

Systems and methods for starting a gas turbine engine can comprise a generator to be driven by the gas turbine engine to supply power to a grid system, a first switch to electrically couple and decouple the generator from the grid system, a first static frequency converter having a first capacity, a second static frequency converter having a second capacity, control means for electrically coupling and decoupling the first and second static frequency converters from the grid system, a synchronizer and a controller configured to operate the generator as a starter-motor with power from: the first static frequency converter to turn the gas turbine engine at a first rate sufficient to start the gas turbine engine within a first time period or the first static frequency converter and the second static frequency converter in synchronization to turn the gas turbine engine at a second rate greater than the first rate.

A thyristor starter accelerates 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 the thyristor starter, during a first time period from start of performance of the second mode to arrival of the induced voltage of the synchronous machine at a first voltage value, a phase control angle of the inverter is changed such that a value thereof becomes larger as a rotation speed of the synchronous machine becomes higher.

Systems and methods for starting a gas turbine engine can comprise a generator to be driven by the gas turbine engine to supply power to a grid system, a first switch to electrically couple and decouple the generator from the grid system, a first static frequency converter having a first capacity, a second static frequency converter having a second capacity, control means for electrically coupling and decoupling the first and second static frequency converters from the grid system, a synchronizer and a controller configured to operate the generator as a starter-motor with power from: the first static frequency converter to turn the gas turbine engine at a first rate sufficient to start the gas turbine engine within a first time period or the first static frequency converter and the second static frequency converter in synchronization to turn the gas turbine engine at a second rate greater than the first rate.

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.

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. The thyristor starter is further configured to raise induced voltage in proportion to the rotation speed of the synchronous machine by keeping field current constant and to suppress rise of the induced voltage by reducing the field current after the induced voltage reaches a first voltage value, in the first mode.