Abstract: The present invention provides a marine propulsion system that is suitable for any civilian and military marine vessels and which offers operational flexibility. The marine propulsion system includes a pair of ac busbars, each in parallel connection with a power converter. The respective power converters each connected in parallel to a propulsion motor.

Abstract: A dc energy store system includes a dc energy store, an AC/DC power converter having ac terminals connected to an ac power supply and dc terminals connected to the dc energy store, and at least one auxiliary unit associated with the dc energy store. The dc energy store system is adapted to be operated in a number of different operating modes including: (i) a first mode to supply power from the ac power supply to the dc energy store; (ii) a second mode to supply power from the dc energy store to the ac power supply; (iii) a third mode to supply power from the ac power supply to the auxiliary unit(s); and (iv) a fault mode where there is a fault in the ac power supply, and power is supplied from the dc energy store to the auxiliary unit(s).

Abstract: An ac synchronous electrical machine includes a stator and a multi-phase stator winding that defines a plurality of stator poles. The stator winding has two or more coil groups, each coil group including a plurality of coils for each phase that are received in winding slots in the stator. The stator winding is connected to a power source/sink. The coil groups are connected in series and each coil group is connected to a power source/sink by a respective switch (26a, 26b . . . ). This allows one or more of the coil groups to be selectively supplied with power from the associated power source/sink or selectively supply power to the associated power source/sink. The switches are operated by a controller. The coils in each coil group are arranged substantially symmetrically around the circumference of the stator to define selected poles of the electrical machine and to produce a constant and balanced rotating torque when any particular coil group or combination of coil groups is active.

Abstract: An assembly includes an electrical machine connected to a power converter by a three-phase circuit having three conductors, e.g. cables Each conductor is associated with a switching device such as a contactor or the like that connects the conductor to a common conductor or terminal. In the event of a fault current being developed in the circuit or the power converter the switching devices are operated to close the fault current and connect together the conductors of the three-phase circuit to provide a full three-phase short circuit.

Abstract: An assembly includes an electrical machine connected to a power converter by a three-phase circuit having three conductors, e.g. cables Each conductor is associated with a switching device such as a contactor or the like that connects the conductor to a common conductor or terminal. In the event of a fault current being developed in the circuit or the power converter the switching devices are operated to close the fault current and connect together the conductors of the three-phase circuit to provide a full three-phase short circuit.

Abstract: A dc energy store includes auxiliary systems operable in different modes, including self-supporting, island mode and normal modes. In the self-supporting mode a first controller uses a voltage demand signal indicative of desired ac voltage of an AC/DC power converter to control semiconductor power switching devices to achieve the desired level of ac voltage. The voltage demand signal is derived from comparing a voltage feedback signal and a second voltage demand signal preset to provide the desired ac voltage for the auxiliary systems. A second controller uses a current demand signal indicative of the desired dc link current to control the semiconductor power switching devices of a DC/DC power converter to achieve the desired level of dc link current. The current demand signal is derived from comparing a dc link voltage demand signal indicative of a desired dc link voltage and a dc link voltage feedback signal.

Abstract: A static energy supply unit has an energy store connected to an ac supply network by a power converter. A unit controller for the static energy supply unit includes an amplitude controller, a phase controller and a frequency controller. These measure and record characteristics of the supply network and provide output signals indicative of the voltage characteristics for an operating condition of the supply network. A signal generator for generating a simulated output voltage signal for each phase of the supply network is provided. A comparator is used to compare the simulated output voltage signal for each phase and a measured voltage for a corresponding phase of the supply network. The controller controls the operation of the power converter to vary the amount of power that is supplied to the supply network from the energy store based on the comparison of the simulated output voltage signal(s) and the measured voltage(s).

Abstract: A wind turbine generator has a drive end at which one or more turbine blades are mountable and a non-drive end. The wind turbine generator comprises an external stator having a radially inner surface and an internal rotor having a radially outer surface, an air gap being defined between the rotor and the stator. A main bearing arrangement is provided at the drive end and acts between the rotor and the stator to mount the rotor for rotation about the stator and a stabiliser bearing is provided at the non-drive end and acts between the rotor and the stator to stabilise the rotor and stator and maintain and control the air gap therebetween.

Abstract: An assembly includes an electrical machine connected to a power converter by a three-phase circuit having three conductors, e.g. cables. Each conductor is associated with a switching device such as a contactor or the like that connects the conductor to a common conductor or terminal. In the event of a fault current being developed in the circuit or the power converter, the switching devices are operated to close the fault current and connect together the conductors or the three-phase circuit to provide a full three-phase short circuit.

Abstract: A dc energy store system includes a dc energy store, an AC/DC power converter having ac terminals connected to an ac power supply and dc terminals connected to the dc energy store, and at least one auxiliary unit associated with the dc enemy store. The dc energy store system is adapted to be operated in a number of different operating modes including: (i) a first mode to supply power from the ac power supply to the dc energy store; (ii) a second mode to supply power from the dc energy store to the ac power supply; (iii) a third mode to supply power from the ac power supply to the auxiliary unit(s); and (iv) a fault mode where there is a fault in the ac power supply, and power is supplied from the dc energy store to the auxiliary unit(s).

Abstract: An ac synchronous electrical machine includes a stator and a multi-phase stator winding that defines a plurality of stator poles. The stator winding has two or more coil groups, each coil group including a plurality of coils for each phase that are received in winding slots in the stator. The stator winding is connected to a power source/sink. The coil groups are connected in series and each coil group is connected to a power source/sink by a respective switch (26a, 26b . . . ). This allows one or more of the coil groups to be selectively supplied with power from the associated power source/sink or selectively supply power to the associated power source/sink. The switches are operated by a controller. The coils in each coil group are arranged substantially symmetrically around the circumference of the stator to define selected poles of the electrical machine and to produce a constant and balanced rotating torque when any particular coil group or combination of coil groups is active.

Abstract: A dc energy store includes auxiliary systems operable in different modes, including self-supporting, island mode and normal modes. In the self-supporting mode a first controller uses a voltage demand signal indicative of desired ac voltage of an AC/DC power converter to control semiconductor power switching devices to achieve the desired level of ac voltage. The voltage demand signal is derived from comparing a voltage feedback signal and a second voltage demand signal preset to provide the desired ac voltage for the auxiliary systems. A second controller uses a current demand signal indicative of the desired dc link current to control the semiconductor power switching devices of a DC/DC power converter to achieve the desired level of dc link current. The current demand signal is derived from comparing a dc link voltage demand signal indicative of a desired dc link voltage and a dc link voltage feedback signal.

Abstract: A static energy supply unit has an energy store 4-connected to an ac supply network by a power converter. A unit controller for the static energy supply unit includes an amplitude controller, a phase controller and a frequency controller. These measure and record characteristics of the supply network and provide output signals indicative of the voltage characteristics for an operating condition of the supply network. A signal generator for generating a simulated output voltage signal for each phase of the ac supply network is provided. A comparator is used to compare the simulated output voltage signal for each phase and a measured voltage for a corresponding phase of the supply network. The controller controls the operation of the power converter to vary the amount of power that is supplied to the supply network from the energy store 4-based on the comparison of the simulated output voltage signal(s) and the measured ac voltage(s).

Abstract: A method of synchronizing a plurality of generators connected together in parallel to a supply network. A common synchronization signal can be generated having a frequency versus time pattern that is the same as the frequency versus time pattern of the supply network during normal operating conditions. The common synchronization signal is then supplied to each of the generators to control the level of power that is supplied to the supply network by the generators.

Abstract: A drive circuit includes an ac network and first and second network rectifier/inverters (which can be active or passive) that are connected to the ac network in parallel. A first PWM rectifier/inverter is connected to the first network rectifier/inverter through a first dc link. A second PWM rectifier/inverter is connected to the second network rectifier/inverter through a second dc link. A first two-layer stator winding having a plurality of individual stator coils is connected to the first PWM rectifier/inverter and a second two-layer stator winding having a plurality of individual stator coils is connected to the second PWM rectifier/inverter. The stator coils of the first stator winding and the stator coils of the second stator winding are interconnected such that, in use, the vector sum of voltages across the stator coils in the first stator winding is substantially equal to the vector sum of voltages across the stator coils in the second stator winding.

Abstract: A method of controlling a power converter is used to interface to a power grid or supply network operating at a frequency (Fnet) that is nominally fixed (say at 50 Hz, for example) but which can be varied as a way of controlling power imbalanced within the network as a whole. The power converter can include a network bridge that operates in accordance with the pulse width modulation (PWM) strategy having a switching frequency (Fpwm), a nominal switching frequency (Fpwm_nom) and a number of pulses per period (Pulse_Number).

Abstract: A multi-transformer unit is operative for converting an input AC voltage at a first voltage level to a net output AC voltage at a second voltage level. The multi-transformer unit can be used in place of a conventional transformer or an AC machine and is designed to suppress the transfer of harmonics between the input and output AC voltages. The unit comprises at least two phase-shifting transformers, each transformer being operative to provide a phase shift relative to the first voltage level. On the primary side of the unit the transformers are arranged for independent connection to the first voltage level, whereas on the secondary side of the unit the transformers are linked such that voltage vectors on the secondary side of the unit are added together to at least partially cancel the harmonic pollution and give the net output AC voltage.

Abstract: A method of synchronizing a plurality of generators connected together in parallel to a supply network. A common synchronization signal can be generated having a frequency versus time pattern that is the same as the frequency versus time pattern of the supply network during normal operating conditions. The common synchronization signal is then supplied to each of the generators to control the level of power that is supplied to the supply network by the generators.

Abstract: A drive circuit includes an ac network and first and second network rectifier/inverters (which can be active or passive) that are connected to the ac network in parallel. A first PWM rectifier/inverter is connected to the first network rectifier/inverter through a first dc link. A second PWM rectifier/inverter is connected to the second network rectifier/inverter through a second dc link. A first two-layer stator winding having a plurality of individual stator coils is connected to the first PWM rectifier/inverter and a second two-layer stator winding having a plurality of individual stator coils is connected to the second PWM rectifier/inverter. The stator coils of the first stator winding and the stator coils of the second stator winding are interconnected such that, in use, the vector sum of voltages across the stator coils in the first stator winding is substantially equal to the vector sum of voltages across the stator coils in the second stator winding.

Abstract: A propeller is driven by an electric motor through a mechanical drive train. The output torque of the motor to the drive train is controlled by a controller with respect to a normal torque reference signal and an emergency torque reference signal. When a measured deceleration of the motor exceeds a threshold deceleration value, the normal torque reference signal is modified or replaced by the emergency torque reference signal and the controller signals the motor to reduce or reverse the torque applied to the mechanical drive train by the motor. In this way, the integrity of the propeller and drive train can be protected if the propeller strikes an underwater obstruction.