A system includes a starter generator configured to provide power to a first bus and a first inverter, a second inverter coupled to the first inverter, a first switch configured to selectively couple the second inverter to the first bus and to a second bus, a second switch configured to selectively couple a first motor to the first bus and to the second bus, and a controller. The controller sets the first switch to a second position and the second switch to a second position, causes the second inverter to convert the power from the first inverter to a starting power for starting the first motor, causes the second inverter to increase the starting power to match the power provided to the first bus from the starter generator, and switches the second switch to the first position, when the starting power matches the power from the starter generator.

Disclosed herein is an apparatus for controlling an inverter. The apparatus determines the phase of an command voltage in a restart section taking into account the frequency of an input voltage to an electric motor when an input power is reduced below a rated power, the frequency of the input voltage into the electric motor at the time of restarting, a time period for generating a torque, and the phase of the input voltage to the electric motor at the time of the restarting.

Disclosed herein is an apparatus for controlling an inverter in an inverter system. The apparatus includes: a first determining unit to determine a magnitude, a phase and a frequency of an input voltage to an electric motor in the inverter system; and a second determining unit to determine a restart command voltage for generating an inverter driving voltage larger than a residual voltage in the electric motor using the magnitude of the input voltage determined by the first determining unit, when the inverter system is restarted.

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 to zero and a second mode of performing commutation of the inverter by induced voltage of the synchronous machine. A second controller controls the firing phase of a thyristor in a converter such that DC output current of the converter matches a current command value, based on a detection signal of a position detector. In the first mode, the current command value is set such that the current value is higher as the rotation speed of the synchronous machine is higher.

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.

An operating circuit and a method for operating a synchronous machine on a voltage supply network is disclosed. The operating circuit has a converter circuit with controllable converter switches and a controllable switching arrangement to switch the converter circuit between a start converter configuration and a direct converter configuration. The power supply network is connected to a converter output and the synchronous machine is connected to a converter input of the converter circuit. In the direct converter configuration, an AC voltage is provided at the converter output with a preset AC voltage frequency. In the direct converter configuration, the switching of the AC voltage between the converter input and the converter output takes place without intermediate rectification.

An operating circuit and a method for operating a synchronous machine on a voltage supply network is disclosed. The operating circuit has a converter circuit with controllable converter switches and a controllable switching arrangement to switch the converter circuit between a start converter configuration and a direct converter configuration. The power supply network is connected to a converter output and the synchronous machine is connected to a converter input of the converter circuit. In the direct converter configuration, an AC voltage is provided at the converter output with a preset AC voltage frequency. In the direct converter configuration, the switching of the AC voltage between the converter input and the converter output takes place without intermediate rectification.

The present disclosure is related to ensuring a period for detecting a phase current from a DC bus current of an inverter. A motor control circuit of the present disclosure includes: a voltage command generator and a PWM signal generator. The voltage command generator detects a phase current from a DC bus current of an inverter driving an AC motor, and generating three-phase voltage commands. The PWM signal generator generates three-phase PWM signals to the inverter according to a comparison result of the three-phase voltage commands and a triangular wave signal with a predetermined frequency and outputs the three-phase PWM signals to the inverter. The PWM signal generator corrects a maximum or minimum voltage command by synchronizing the maximum or minimum voltage command with an intermediate command in a first period of multiple consecutive PWM periods.

A current sourced control topology is provided for an AC motor controller that eliminates many of the problems associated with prior art motor controllers that use voltage source inverter (VSI) technologies. By controlling the output of AC current sources such as synchronously controlled down converters to directly drive each motor phase, significant efficiency gains and a reduction in electromagnetic interference is achievable.

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.