Electrical systems for connecting rotary electric machines to dc networks operating at different voltages V and W where V>W along with gas turbine engine arrangements incorporating such systems.

A charging system includes an AC/DC converter a DC/DC converter, and a control circuit. The AC/DC converter is connected between first/second input nodes and first/second intermediate nodes and is connected to an AC power supply via the first/second input nodes. The DC/DC converter is connected between the first/second intermediate nodes and first/second output nodes and is connectable to a battery via the first/second output nodes. The DC/DC converter includes an isolation transformer, a primary circuit, and a secondary circuit. The primary circuit includes switching elements. The control circuit causes the switching elements to start operation at a first frequency when the AC/DC converter and the DC/DC converter are activated, and causes the switching elements to operate at a second frequency when the AC/DC converter and the DC/DC converter are in steady operation. The first frequency is higher than the second frequency.

A charging system includes an AC/DC converter a DC/DC converter, and a control circuit. The AC/DC converter is connected between first/second input nodes and first/second intermediate nodes and is connected to an AC power supply via the first/second input nodes. The DC/DC converter is connected between the first/second intermediate nodes and first/second output nodes and is connectable to a battery via the first/second output nodes. The DC/DC converter includes an isolation transformer, a primary circuit, and a secondary circuit. The primary circuit includes switching elements. The control circuit causes the switching elements to start operation at a first frequency when the AC/DC converter and the DC/DC converter are activated, and causes the switching elements to operate at a second frequency when the AC/DC converter and the DC/DC converter are in steady operation. The first frequency is higher than the second frequency.

A controller (5) of an uninterruptible power supply apparatus includes: first to sixth comparator circuits (22a to 22f) respectively provided corresponding to first to sixth IGBTs (Q1 to Q6) and outputting, based on a comparison result of the magnitude of three-phase AC voltages, signals (A1 to A6) indicating that a corresponding IGBT is to be turned on; and a control unit (23) that, when a voltage between terminals (VD1 or VD2) of a first or second capacitor (C11 or C12) is higher than a target voltage (VDT), turns on and off each of the first to sixth IGBTs based on signals output from the first to sixth comparator circuits to decrease the voltage between terminals of the first or second capacitor.

A power conversion system includes N power converters. Each power converter includes an input terminal, a first output terminal and a second output terminal. Each of the N power converters receives a DC power through the input terminal. The first output terminal of a first power converter and the second output terminal of an N-th power converter are connected in parallel to form an N-th total output terminal. The first output terminal of an i-th power converter and the second output terminal of an (i−1)-th power converter are connected in parallel to form an (i−1)-th total output terminal. The two input terminals of the load are connected with two total output terminals of N total output terminals. A (2k−1)-th power converter is connected with a first power source. A 2k-th power converter is connected with a second power source. The redundancy of the power conversion system can be achieved.

A lumped power supply circuit for converting an AC signal into a DC signal, the lumped power supply circuit including: a cascaded H-bridge circuit having N H-bridge sub-circuits connected in series between two input terminals of the AC signal, and being configured to convert the AC signal into N first voltage signals, where N is a positive integer greater than or equal to 2; a high-frequency filtering module configured to filter the N first voltage signals, and to generate N second voltage signals; a DC conversion module to receive the N second voltage signals, and to convert the N second voltage signals into at least one third voltage signal; and a lumped power buffer module having an output terminal coupled to a load, and being configured to receive the at least one third voltage signal, and to filter out part of power frequency fluctuations in the third voltage signal.

A lumped power supply circuit for converting an AC signal into a DC signal, the lumped power supply circuit including: a cascaded H-bridge circuit having N H-bridge sub-circuits connected in series between two input terminals of the AC signal, and being configured to convert the AC signal into N first voltage signals, where N is a positive integer greater than or equal to 2; a high-frequency filtering module configured to filter the N first voltage signals, and to generate N second voltage signals; a DC conversion module to receive the N second voltage signals, and to convert the N second voltage signals into at least one third voltage signal; and a lumped power buffer module having an output terminal coupled to a load, and being configured to receive the at least one third voltage signal, and to filter out part of power frequency fluctuations in the third voltage signal.

A power converting apparatus includes: a first arm including a switching element and a switching element connected in series; a second arm including a switching element and a switching element connected in series, the second arm being connected in parallel with the first arm; a reactor having one end connected to the switching element and the switching element and an opposite end connected to an alternating-current power supply; and a smoothing capacitor connected in parallel with the first arm and the second arm. The loss characteristic of the switching element and the second switching element that occurs in each switching event is better than the loss characteristic of the switching element and the switching element that occurs in each switching event.

A rectifier arrangement (20) for rectifying an AC voltage into a DC voltage has connections, circuit arrangements, an interconnection apparatus (26) and an intermediate circuit (50). The connections include first and second connections (22, 21). The intermediate circuit (50) has a first line (51), a second line (52) and at least one capacitor (61, 62) between the first and second lines (51, 52). The circuit arrangements (31, 32, 33, 34, 35, 36) each have a first circuit arrangement connection (A) and a second circuit arrangement connection (B), between which a changeover arrangement (92) and a coil (91) are connected in series. The interconnection apparatus (26) enables at least: a first configuration in which the first connection (22) is connected to at least one first circuit arrangement connection (A), and a second configuration in which the first connection (22) is connected to at least one second circuit arrangement connection (B).

The present disclosure provides a three-phase AC/DC converter aiming for low input current harmonic. The converter includes an input stage for receiving a three-phase AC input voltage, an output stage for at least one load, and one or more switching conversion stages, each stage including a plurality of half bridge modules. The switches in each module operate with a substantially fixed 50% duty cycle and are connected in a specific pattern to couple a DC-link and a neutral node of the input voltage. The AC/DC converter further includes one or more controllers adapted to vary the switching frequency of the switches in the switching conversion stages based on at least one of load voltage, load current, input voltage, and DC-link voltage. The converter can also include one or more decoupling stages, such as, inductive components adapted to decouple the output stage from the switching conversion stages.