A frequency converter with a rectifier on an input side and a backup capacitor arranged downstream of the rectifier. Input-side phases of the rectifier feed the backup capacitor via multiple half-bridges of the rectifier. The input-side phases are connected to grid-side phases of a multiphase supply grid via a pre-circuit. Each grid-side phase is connected to an input-side phase within the pre-circuit via a phase capacitor. Each grid-side phase is additionally directly connected to another input-side phase within the pre-circuit via a switch and the grid-side phases are short-circuited with the input-side phases when the switches are closed. Each phase capacitor connects two grid-side phases or two input-side phases together. The frequency converter has a control apparatus which keeps the switches open when pre-charging the backup capacitor and closes the switches when a specified charge state of the backup capacitor is reached.

A frequency converter includes a rectifier on an input side and a support capacitor downstream of the rectifier. Input-side phases of the rectifier feed the backup capacitor via multiple half-bridges of the rectifier. The half-bridges have active switching elements and the rectifier is designed as a recovery rectifier. The input-side phases are connected to grid-side phases of a multiphase supply grid via an upstream circuit. Each grid-side phase is connected to one of the input-side phases within the upstream circuit via a respective phase capacitor. A control facility controls the active switching elements when a first charge state of the support capacitor is reached and input-side phase voltages are applied to the input-side phases via the active switching elements. Voltages running in the opposite direction to the grid-side phase voltages are applied to the grid-side phases to which the input-side phases are connected via the phase capacitors.

A frequency converter with a rectifier on an input side and a backup capacitor arranged downstream of the rectifier. Input-side phases of the rectifier feed the backup capacitor via multiple half-bridges of the rectifier. The input-side phases are connected to grid-side phases of a multiphase supply grid via a pre-circuit. Each grid-side phase is connected to an input-side phase within the pre-circuit via a phase capacitor. Each grid-side phase is additionally directly connected to another input-side phase within the pre-circuit via a switch and the grid-side phases are short-circuited with the input-side phases when the switches are closed. Each phase capacitor connects two grid-side phases or two input-side phases together. The frequency converter has a control apparatus which keeps the switches open when pre-charging the backup capacitor and closes the switches when a specified charge state of the backup capacitor is reached.

A frequency converter includes a rectifier on an input side and a support capacitor downstream of the rectifier. Input-side phases of the rectifier feed the backup capacitor via multiple half-bridges of the rectifier. The half-bridges have active switching elements and the rectifier is designed as a recovery rectifier, The input-side phases are connected to grid-side phases of a multiphase supply grid via an upstream circuit. Each grid-side phase is connected to one of the input-side phases within the upstream circuit via a respective phase capacitor. A control facility controls the active switching elements when a first charge state of the support capacitor is reached and input-side phase voltages are applied to the input-side phases via the active switching elements. Voltages running in the opposite direction to the grid-side phase voltages are applied to the grid-side phases to which the input-side phases are connected via the phase capacitors.

An apparatus for an alpha trim adjustment includes a phase delay circuit that creates a phase delay for a gate signal for a switching cycle. The gate signal is for a phase of a three-phase, phase shifted alternating current (AC) input of a multi-pulse motor drive powering a direct current (DC) motor. The apparatus includes an alpha trim circuit that modifies the phase delay with an alpha trim adjustment to create an adjusted phase delay for the switching cycle, a delay application circuit that applies the adjusted phase delay to the gate signal.

A method and device is disclosed for charging and/or maintenance of lead-acid and alkaline accumulator batteries, allowing a charge, discharge, or recovery in control-conditioning cycles of these batteries. To increase efficiency of the battery recovery process, its charge is created by a reversible current in consecutive stages. Correction of the charging mode is provided based on voltage and temperature of the accumulator battery.

An apparatus for an alpha trim adjustment includes a phase delay circuit that creates a phase delay for a gate signal for a switching cycle. The gate signal is for a phase of a three-phase, phase shifted alternating current (AC) input of a multi-pulse motor drive powering a direct current (DC) motor. The apparatus includes an alpha trim circuit that modifies the phase delay with an alpha trim adjustment to create an adjusted phase delay for the switching cycle, a delay application circuit that applies the adjusted phase delay to the gate signal.

A method and device is disclosed for charging and/or maintenance of lead-acid and alkaline accumulator batteries, allowing a charge, discharge, or recovery in control-conditioning cycles of these batteries. To increase efficiency of the battery recovery process, its charge is created by a reversible current in consecutive stages. Correction of the charging mode is provided based on voltage and temperature of the accumulator battery.

AC/DC converter wherein a three-phase trans former (2) comprises a plurality of first secondary windings (4-a, 4-b, . . . 4-n) magnetically linked with a first primary winding (3-T), a plurality of second secondary windings (5-a, 5-b, . . . 5-n) magnetically linked with a second primary winding (3-S) and a plurality of third secondary windings (6-a, 6-b, . . . 6-n) magnetically linked with a third primary winding (3-R). There is provided a plurality of first, second and third reconfigurable connection modules each of which is respectively connected on the input side with a first, a second and a third secondary winding; the outputs of the first reconfigurable connection modules being connected in series to one another, the outputs of the second reconfigurable connection modules being connected in series to one another and the outputs of the third reconfigurable connection modules are connected in series to one another. Each reconfigurable module comprises electronic switches selectively controllable so that three connections can be made, including a direct connection, wherein the voltage supplied at the input of the reconfigurable connection module is transferred to its output with the same polarity, a bypass connection, wherein the output of the re configurable connection module is short-circuited and the output voltage at the module is substantially equal to zero, and a reverse connection, wherein the voltage supplied at the input of the re configurable connection module is transferred to its output with reversed polarity.

AC/DC converter wherein a three-phase trans former (2) comprises a plurality of first secondary windings (4-a, 4-b, . . . 4-n) magnetically linked with a first primary winding (3-T), a plurality of second secondary windings (5-a, 5-b, . . . 5-n) magnetically linked with a second primary winding (3-S) and a plurality of third secondary windings (6-a, 6-b, . . . 6-n) magnetically linked with a third primary winding (3-R). There is provided a plurality of first, second and third reconfigurable connection modules each of which is respectively connected on the input side with a first, a second and a third secondary winding; the outputs of the first reconfigurable connection modules being connected in series to one another, the outputs of the second reconfigurable connection modules being connected in series to one another and the outputs of the third reconfigurable connection modules are connected in series to one another. Each reconfigurable module comprises electronic switches selectively controllable so that three connections can be made, including a direct connection, wherein the voltage supplied at the input of the reconfigurable connection module is transferred to its output with the same polarity, a bypass connection, wherein the output of the re configurable connection module is short-circuited and the output voltage at the module is substantially equal to zero, and a reverse connection, wherein the voltage supplied at the input of the re configurable connection module is transferred to its output with reversed polarity.