A third power supply circuit subjects a reference voltage to DC-DC conversion to generate a power supply voltage common to a second driver circuit for driving a second switching device and a fourth driver circuit for driving a fourth switching device. Wirings from a substrate on which the third power supply circuit is provided to a substrate on which the second driver circuit and the fourth driver circuit are provided are used by the third power supply circuit to supply the power supply voltage commonly to the second driver circuit and the fourth driver circuit. A first impedance device, a second impedance device, a third impedance device, and a fourth impedance device are provided in a substrate on which the second driver circuit and the fourth driver circuit are provided.

A switching element driving device for driving first and second switching elements of a half bridge circuit, the first and second switching elements being respectively formed in upper and lower arm units of the half bridge, and having respectively first and second freewheeling diodes connected thereto in antiparallel. The switching element driving device includes upper and lower arm driving circuits respectively configured to output first and second driving signals for driving the first and second switching elements, and a drive capability decision circuit configured to, responsive to turning on of the first switching element, set drive capability of the first driving signal to a first level and to change the drive capability of the first driving signal to a second level upon detecting a reverse recovery current of the second freewheeling diode of the second switching element, the first level being higher than the second level.

A switching element driving device for driving first and second switching elements of a half bridge circuit, the first and second switching elements being respectively formed in upper and lower arm units of the half bridge, and having respectively first and second freewheeling diodes connected thereto in antiparallel. The switching element driving device includes upper and lower arm driving circuits respectively configured to output first and second driving signals for driving the first and second switching elements, and a drive capability decision circuit configured to, responsive to turning on of the first switching element, set drive capability of the first driving signal to a first level and to change the drive capability of the first driving signal to a second level upon detecting a reverse recovery current of the second freewheeling diode of the second switching element, the first level being higher than the second level.

A power conversion system includes: an output terminal connected to a load; a switch configured to be turned on in a first case that an AC voltage from the AC power supply is normal, and to be turned off in a second case that the AC voltage from the AC power supply is abnormal; a power converter configured to convert the AC power from the AC power supply into DC power and store the DC power in a storage battery in the first case, and to convert the DC power in the storage battery into AC power and output the AC power to the output terminal in the second case; and a line-commutated inverter configured to operate in synchronization with an AC voltage appearing at the output terminal, and convert the DC power supplied from a fuel cell into AC power and output the AC power to the output terminal.

A power conversion system includes: an output terminal connected to a load; a switch configured to be turned on in a first case that an AC voltage from the AC power supply is normal, and to be turned off in a second case that the AC voltage from the AC power supply is abnormal; a power converter configured to convert the AC power from the AC power supply into DC power and store the DC power in a storage battery in the first case, and to convert the DC power in the storage battery into AC power and output the AC power to the output terminal in the second case; and a line-commutated inverter configured to operate in synchronization with an AC voltage appearing at the output terminal, and convert the DC power supplied from a fuel cell into AC power and output the AC power to the output terminal.

A power inverter system includes switching mode inverter legs connected in parallel between a common DC input and, via leg output inductors, a common phase output to feed a phase output current to a common load. The commutations of the parallel-connected inverter legs are initiated by essentially simultaneous commutation commands. The leg output current is sensed before and after a commutation in each of the parallel-connected inverter legs to obtain a pre-commutation current value and a post-commutation current value. Alternatively, a voltage pulse over the leg output inductor is sensed in each of the parallel-connected inverter legs during the commutation. A current sharing between the parallel-connected inverter legs is balanced by means of adjusting switching instants of main switches of the parallel-connected inverter legs for subsequent commutation autonomously in each of the parallel-connected inverter legs based on a difference between the pre-commutation and the post-commutation current values or based on the sensed voltage pulse of the respective parallel-connected inverter leg.

An electrical assembly comprising power conversion system (PCM) having an output (OT1), a filter device (2) connected to the output (OT1) of the power conversion system (PCM), a pre-charging circuit (PCC), and an interface (ITF) for connecting the electrical assembly to an electrical power network (GRD). The filter device (2) comprises inductor system and filter capacitor system adapted to co-operate with the inductor system for filtering an alternating current. The filter device (2) comprises a capacitor switch device (S3) for disconnecting the filter capacitor system from the inductor system. The electrical assembly comprises a grid switch device (S4) connected in parallel with the pre-charging circuit (PCC). The parallel connected pre-charging circuit (PCC) and grid switch device (S4) are operationally connected between the output (OT1) of the power conversion system (PCM) and the interface (ITF) of the electrical assembly.

A voltage source converter has director valve phase legs in parallel with waveshaper phase legs between two DC terminals. The director valve and waveshaper phase legs include upper and lower phase arms alternately operated to form waveshapes on AC terminals of the converter, thereby allowing a number of waveshaper phase arms to be available for use for other purposes. At least one of the available phase arms is controlled to contribute to other aspects of converter operation than waveshaping.

A system includes multiple electrical nodes connected in series to a primary power source via transmission lines. Each node includes a power converter that can receive first power from the primary power source or another upstream node. The power converter can change a voltage level and/or a frequency of the first power. Each node also includes a high-speed synchronous rotating machine (HSRM), which includes an inertial storage flywheel, a rotating excitation assembly, stator windings, and a synchronous motor coupled to an induction generator. The HSRM can boost a voltage level between an input and output to compensate for a voltage drop of the first power. At least one of the nodes further includes an inductive power coupler to electrically couple the node to a mobile power source that provides second power to the node and receives a portion of the first power from the node using contactless inductive power transfer. The system includes a combination of AC and DC power transmission techniques and associated bidirectional power converters.

An electrical motor system and a method for operating the electrical motor system are disclosed. The electrical motor system comprises a direct current (DC) source, a filter connected in parallel with the DC source and an electric motor with at least two sets of windings. A voltage signal is provided from the DC source to the inverter circuit where the signal is modulated. The modulated signal is then supplied from the inverter circuit to each set of windings with a respective time offset between each set of windings respectively, providing a very efficient DC bus ripple reduction. Hereby, it is e.g. possible to use small filter capacitors/capacitor banks in electrical motor systems.