A method for controlling a three-phase electrical converter comprises: selecting a three-phase optimized pulse pattern from a table of pre-computed optimized pulse patterns based on a reference flux; determining a two-component optimal flux from the optimized pulse pattern and determine a one-component optimal third variable; determining a two-component flux error from a difference of the optimal flux and an estimated flux estimated based on measurements in the electrical converter; determining a one-component third variable error from a difference of the optimal third variable and an estimated third variable; modifying the optimized pulse pattern by time-shifting switching instants of the optimized pulse pattern such that a cost function depending on the time-shifts is minimized, wherein the cost function comprises a flux error term and a third variable error term, wherein the flux error term is based on a difference of the flux error and a flux correction function providing a flux correction based on the time-shifts and the third variable error term is based on a difference of the third variable error and a third variable correction function providing a third variable correction based on the time-shifts; and applying the modified optimized pulse pattern to the electrical converter.

A method of commutation in a matrix rectifier from an active vector to a zero vector includes two steps. A method of commutation in a matrix rectifier from a zero vector to an active vector includes three steps.

The direct current (DC) side fault isolator for high voltage direct current (HVDC) converters (10) includes a first set of double thyristor switches (12) connected across the line-to-line voltage terminals between first and second phases of alternating current (AC) terminals of a HVDC converter (14), and a second set of double thyristor switches (12) connected across the line-to-line voltage between the second phase and a third phase of the AC terminals of the HVDC converter (14). In use, the first and second sets of double thyristor switches (12) separate the HVDC converter (10) from an external power grid (18) during direct current (DC) side faults by turning on these thyristors (12).

The direct current (DC) side fault isolator for high voltage direct current (HVDC) converters (10) includes a first set of double thyristor switches (12) connected across the line-to-line voltage terminals between first and second phases of alternating current (AC) terminals of a HVDC converter (14), and a second set of double thyristor switches (12) connected across the line-to-line voltage between the second phase and a third phase of the AC terminals of the HVDC converter (14). In use, the first and second sets of double thyristor switches (12) separate the HVDC converter (10) from an external power grid (18) during direct current (DC) side faults by turning on these thyristors (12).

A circuit arrangement for providing electrical power for at least one DC load from at least one alternating current source having a primary DC intermediate voltage circuit. The primary DC intermediate voltage circuit is supplied with electrical power of the alternating current source via two rectifiers connected in series such that a centre point tap is provided, means for limiting the DC output voltage of the associated rectifier are provided between the centre point tap of the primary DC intermediate voltage circuit and at least one DC potential of the primary DC intermediate voltage circuit, which can limit the DC output voltage of at least one of the rectifiers connected in series in the event of a fault state in the DC load, in the secondary DC intermediate voltage circuit and/or in at least one of the DC/DC converters.

An AC/DC converter including a PFC circuit. The PFC circuit includes: a reactor; a first thyristor and a second thyristor; at least one switching element; and a capacitor. When an input of an alternating-current voltage is started, with a function of the switching element being made inactive, a controller executes a soft start by adjusting a pulse width when each of the thyristors is turned ON by changing a timing when each of the thyristors is turned ON based on a phase angle.