A supercritical CO2 turbo-generator system is disclosed. The turbo-generator system comprises: a plurality of turbine generator units (200A-200C), a direct current bus (410), a plurality of active rectifiers (290A-290C), and a voltage controller (280). Each of plurality of turbine generator units comprises: a turbine (312) with a supercritical CO2 input and a supercritical CO2 output, a generator (326) with an electrical input and power output, a shaft (314) connecting the turbine and generator, and a speed sensor (327) for determining a speed of the associated shaft. The plurality of turbine generator units are connected in the form of a cascading series with the input of a first turbine generator unit (200A) connected to a source of heated supercritical CO2. The input of a second turbine generator unit (200B) is connected to the output of the first turbine generator unit. The input of a third turbine generator unit (200C) is connected to the output of the second turbine generator unit. The voltage controller (280) is configured to monitor the speed sensor (327) of each of the plurality of turbine generator units and vary the load on each generator (230A-230C) to control shaft (314) speed. Each of the plurality of active rectifiers (290A-290C) then converts the power output of a generator (230A-230C) to direct current, and the power from the plurality of active rectifiers then combined by the direct current bus.

A voltage fluctuation suppressing device for an alternating current generator provided in the alternating current generator and configured to suppress voltage fluctuation by excitation control based on an output voltage includes a processor, and a memory configured to be able to communicate with the processor. The processor is configured to: detect a load current of each of output terminals; identify in-use output terminals based on the detection of the load current; detect inter-terminal voltages of the output terminals including the identified output terminals; and control excitation by using an output voltage calculated from the detected inter-terminal voltages.

A rotary electrical machine including an annular stator having a stator core around which an armature winding is wound, and a rotor arranged on an inner circumference of the stator, a permeance of a q-axis magnetic circuit is made larger than a permeance of a d-axis magnetic circuit. The machine includes a switch for supplying power to a field winding and controller. The controller calculates the duty ratio on the condition that an upper limit of the duty ratio of the switch is a predetermined value and turns on/off the switch based on the calculated ratio. The predetermined value is set to a value larger than the duty ratio corresponding to the field current that gives the maximum reduction amount of the inductance of the field winding with respect to an increasing amount of the field current in a range that the current can take and is less than 100%.

An inverter type engine generator includes an alternator operable as a motor for starting an engine; a converter composed of a three-phase rectifying bridge circuit, converting three-phase alternating current output from the alternator into direct current, and operatable as a motor driver for driving the alternator when power is supplied from a power source; and a processor and a memory. The upper and lower three sets of elements of the three-phase rectifying bridge circuit of the converter are configured such that upper elements are configured from duty-controllable switching elements and thyristors connected in parallel therewith, and lower elements are configured from duty-controllable switching elements having diodes. The processor and the memory perform turning off the lower elements and controlling the duty of the thyristors while turning off the upper elements so that an output voltage of the three-phase rectifying bridge circuit is reduced, when a detected terminal voltage of the converter exceeds the target voltage.

A method of performing de-excitation of a brushless synchronous machine having a stator; and a rotor including: a field winding, an exciter armature, a rectifier having thyristors, the rectifier having input terminals connected to the exciter armature and output terminals connected to the field winding, a field discharge resistor connected in series with the field winding, and a bypass switch connected in parallel with the field discharge resistor, the bypass switch being operable between a closed state in which the field discharge resistor is bypassed, and an open state, wherein the method including: a) controlling the thyristors to fire only during a negative half-cycle of the armature voltage waveforms, and b) controlling the bypass switch to obtain the open state from the closed state to thereby discharge a field winding current through the field discharge resistor.

A power conversion device, comprising: an energization device (END) applying a voltage to armature and field windings of a rotating electrical machine (REM) according to an energization signal (ENS), and having inverter and alternator power generation modes (I-PGM,A-PGM); a power-generation switching signal generator (PGSSG) generating a power-generation switching signal (GES) for switching the I-PGM, A-PGM according to switching of a first selection (FSS) switching the modes arbitrarily and a second selection (SSS) switching the modes base on a maximum output in the modes; a voltage command generator (VCG) generating an armature voltage command (AVC) and a field voltage command (FVC) based on a REM output command (REMC); an energization signal generator (ESG) generating the ENS corresponding to armature and field windings based on AVC, FVC, GES and DC voltage of END, wherein PGSSG generates the GES by switching FSS, SSS regarding a rotating electrical machine output command MOC value.

A power conversion device, comprising: an energization device (END) applying a voltage to armature and field windings of a rotating electrical machine (REM) according to an energization signal (ENS), and having inverter and alternator power generation modes (I-PGM,A-PGM); a power-generation switching signal generator (PGSSG) generating a power-generation switching signal (GES) for switching the I-PGM, A-PGM according to switching of a first selection (FSS) switching the modes arbitrarily and a second selection (SSS) switching the modes base on a maximum output in the modes; a voltage command generator (VCG) generating an armature voltage command (AVC) and a field voltage command (FVC) based on a REM output command (REMC); an energization signal generator (ESG) generating the ENS corresponding to armature and field windings based on AVC, FVC, GES and DC voltage of END, wherein PGSSG generates the GES by switching FSS, SSS regarding a rotating electrical machine output command MOC value.

A rotary electrical machine includes a switch for supplying power to a field winding and controller. A ratio of an on-time to one switching cycle of the switch is defined as a duty ratio, and a duty ratio which is larger than the duty ratio corresponding to the field current that gives the maximum reduction amount of the inductance of the field winding with respect to an increasing amount of the field current in a range that the current can take and has a value less than 100% is set as a predetermined value. The controller calculates the duty ratio wherein an upper limit of the ratio is the predetermined value and turns on/off the switch based on the calculated duty ratio. Also, a relay and abnormality detection part that detects abnormality in the switch. The relay is switched to off in response to the occurrence of abnormality being detected.

Disclosed herein is a converter for converting an AC voltage to a DC voltage, the converter comprising: a first H-bridge circuit comprising a first AC terminal for receiving an AC voltage, a second AC terminal, a first DC terminal and a second DC terminal; a second H-bridge circuit comprising a first AC terminal for receiving an AC voltage, a second AC terminal, a first DC terminal and a second DC terminal; an isolation block arranged between the second AC terminal of the first H-bridge circuit and the second AC terminal of the second H-bridge circuit; and a DC voltage output of the converter with a first terminal and a second terminal; wherein: the first terminal of the DC voltage output is connected to the first DC terminal of the first H-bridge circuit and the first DC terminal of the second H-bridge circuit; and the second terminal of the DC voltage output is connected to the second DC terminal of the first H-bridge circuit and the second DC terminal of the second H-bridge circuit.

A control method and a switching device are provided for a separately excited synchronous machine as a drive in a hybrid or electric vehicle. The switching device converts and/or distributes electrical energy within the vehicle, in particular the hybrid or electric vehicle, wherein an asymmetric full bridge is provided, in the bridge branch of which a rotor of an SSM is arranged. Switches are provided in the asymmetric full bridge in order to provide a pulse width modulation corresponding to a desired motor rotational speed and power of the SSM. The device is characterized in that it has a short-circuit branch extending in parallel with the bridge branch of the asymmetric full bridge, by which short-circuit branch the rotor of the SSM is able to be short-circuited.