Apparatus and method for supplying direct current with superimposed alternating current

Claim 1

A DC+AC power supply comprising: (a) a transformer having at least two star-connected phase windings in the secondary, at least one of these windings being an ordinary winding used exclusively for supplying an AC voltage to a rectifier system, and at least one of these windings being an unbalancing winding used for supplying AC voltage to a rectifier system and also for providing an additional AC voltage component across a load; (b) a rectifier system having at least two rectifier circuit elements, each circuit element having two terminals, one terminal being connected to any phase-winding of the secondary of the transformer, the other terminal being connected to a first output terminal, all rectifier circuit elements having the same direction with respect to said first output terminal, whereby each of the phase-windings is connected to a corresponding rectifier circuit element; (c) a load having a first and a second terminal, the first load terminal being connected to the first output terminal, and the second load terminal being connected to any point of the unbalancing winding, said point being different from the point of star connection of transformer windings, whereby an additional AC voltage component is introduced across the load, said AC voltage being superimposed on a DC voltage across said load.

Claim 16

A method for providing an AC voltage superimposed on a DC voltage, the method comprising the steps of: (a) supplying an at least one-phase voltage to a modifying transformer with star-connected phase windings in the secondary; (b) modifying said AC voltage into a first and a second voltage with the help of said transformer, the first voltage being an at least one-phase voltage and being created with the help of at least one ordinary winding of the secondary of said transformer, said first AC voltage being used for supplying an AC current to a system of rectifier circuit elements, the second voltage being an unbalancing voltage and being created by one of the ordinary phase windings which is also an unbalancing winding, said second voltage being used for changing the AC potential of one terminal of a load; (c) rectifying said first voltage with the help of rectifying circuit elements for providing a rectified voltage across the load; (d) coupling a first load terminal with rectifier circuit elements and a second load terminal with a point of star-connection of the secondary of the transformer, whereby a DC voltage with a minimum AC ripple voltage is introduced across the load; (d) changing the AC potential of the second load terminal by connecting said terminal to any point of the unbalancing winding whereby an additional AC voltage superimposed on the DC voltage is introduced across the load, said AC voltage being changed as the second load terminal is connected to different points along the unbalancing winding;

Claim 17

A method for providing an AC voltage superimposed on a DC voltage, the method comprising the steps of: (a) supplying an at least one-phase voltage to a modifying transformer with star-connected phase windings in the secondary; (b) modifying said AC voltage into a first and a second voltage with the help of said transformer, the first voltage being an at least one-phase voltage and being created with the help of at least one ordinary winding of the secondary of said transformer, said first AC voltage being used for supplying an AC current to a system of rectifier circuit elements, the second voltage being an unbalancing voltage and being created by one of the ordinary phase windings which is also an unbalancing winding, said second voltage being used for changing the AC potential of one terminal of a load; (c) rectifying said first voltage with the help of rectifying circuit elements for providing a rectified voltage across the load; (d) coupling a first load terminal with rectifier circuit elements and a second load terminal with a point of star-connection of the secondary of the transformer, whereby a DC voltage with a minimum AC ripple voltage is introduced across the load; (d) changing the AC potential of the second load terminal by connecting said terminal to any point of the unbalancing winding whereby an additional AC voltage superimposed on the DC voltage is introduced across the load, said AC voltage being changed as the second load terminal is connected to different points along the unbalancing winding;

Claim 19

A method for providing an AC voltage superimposed on DC voltage, the method comprising the steps of: (a) supplying an at least one-phase AC voltage to a modifying transformer with star-connected phase windings in the secondary; (b) modifying said AC voltage into a first and a second voltage with the help of said transformer, the first voltage being an at least one-phase voltage and being created with the help of at least one ordinary winding of the secondary of said transformer, said first AC voltage being used for supplying an AC current to a system of rectifier circuit elements, the second voltage being an unbalancing voltage and being created by one of the phase-windings of the secondary which is an unbalancing winding, the second voltage being used for changing the AC potential of one terminal of a load; (c) rectifying said first voltage with the help of rectifying circuit elements for providing a rectified voltage across the load; (d) coupling a first load terminal with rectifier circuit elements and a second load terminal with a point of star connection of the secondary of the transformer, whereby a DC voltage with a minimum AC ripple voltage is introduced across the load; (e) changing the AC potential of the second load terminal by connecting said terminal to any point of the unbalancing winding thereby an additional AC voltage superimposed on the DC voltage is introduced across the load, said AC voltage being changed as the second load terminal is connected to different points along the unbalancing winding.

Claim 20

A method for providing an AC voltage superimposed on DC voltage, the method comprising the steps of: (a) supplying an at least one-phase AC voltage to a modifying transformer with star-connected phase windings in the secondary; (b) modifying said AC voltage into a first and a second voltage with the help of said transformer, the first voltage being an at least one-phase voltage and being created with the help of at least one ordinary winding of the secondary of said transformer, said first AC voltage being used for supplying an AC current to a system of rectifier circuit elements, the second voltage being an unbalancing voltage and being created by one of the phase-windings of the secondary which is an unbalancing winding, the second voltage being used for changing the AC potential of one terminal of a load; (c) rectifying said first voltage with the help of rectifying circuit elements for providing a rectified voltage across the load; (d) coupling a first load terminal with rectifier circuit elements and a second load terminal with a point of star connection of the secondary of the transformer, whereby a DC voltage with a minimum AC ripple voltage is introduced across the load; (e) changing the AC potential of the second load terminal by connecting said terminal to any point of the unbalancing winding thereby an additional AC voltage superimposed on the DC voltage is introduced across the load, said AC voltage being changed as the second load terminal is connected to different points along the unbalancing winding.

Claim 22

A method for providing an AC voltage superimposed on a DC voltage, the method comprising the steps of: (a) supplying an at least one-phase sinusoidal AC voltage to a saturable core reactor; (b) modifying said sinusoidal voltage into non-sinusoidal voltage with the help of said reactor and also controlling the value of said non-sinusoidal voltage by said reactor; (c) supplying said non-sinusoidal voltage to a modifying transformer with star-connected phase-windings in the secondary; (d) modifying said AC voltage into a first and a second voltage with the help of said transformer, the first voltage being an at least one-phase voltage, and being created with the help of at least one ordinary winding of the secondary of said transformer, said first AC voltage being used exclusively for supplying an AC current to a system of rectifier circuit elements, the second voltage being an unbalancing voltage and being created by one of the phase windings of the secondary which is an unbalancing winding, the second voltage being used for changing the AC potential of one terminal of a load; (e) rectifying said first voltage with the help of rectifying circuit elements for providing a rectified voltage across the load; (f) coupling a first load terminal with rectifier circuit elements and a second load terminal with a point of star connection of the secondary of the transformer, whereby a DC voltage with a minimum AC ripple voltage is introduced across the load; (g) changing the AC potential of the second load terminal by connecting said terminal to any point of the unbalancing winding whereby an additional AC voltage superimposed on the DC voltage is introduced across the load, said AC voltage being changed as the second load terminal is connected to different points along the unbalancing winding; (h) coupling terminals of at least one capacitor with the transformer and rectifier circuit elements, so that one capacitor terminal is connected to the point of star connection of the transformer secondary, and the other terminal is connected to the same point of the rectifier system to which the first load terminal is connected, whereby the waveform of the AC component across the load is changed as capacitance of the capacitor increases.

Claim 23

A method for providing an AC voltage superimposed on a DC voltage, the method comprising the steps of: (a) supplying an at least one-phase sinusoidal AC voltage to a saturable core reactor; (b) modifying said sinusoidal voltage into non-sinusoidal voltage with the help of said reactor and also controlling the value of said non-sinusoidal voltage by said reactor; (c) supplying said non-sinusoidal voltage to a modifying transformer with star-connected phase-windings in the secondary; (d) modifying said AC voltage into a first and a second voltage with the help of said transformer, the first voltage being an at least one-phase voltage, and being created with the help of at least one ordinary winding of the secondary of said transformer, said first AC voltage being used exclusively for supplying an AC current to a system of rectifier circuit elements, the second voltage being an unbalancing voltage and being created by one of the phase windings of the secondary which is an unbalancing winding, the second voltage being used for changing the AC potential of one terminal of a load; (e) rectifying said first voltage with the help of rectifying circuit elements for providing a rectified voltage across the load; (f) coupling a first load terminal with rectifier circuit elements and a second load terminal with a point of star connection of the secondary of the transformer, whereby a DC voltage with a minimum AC ripple voltage is introduced across the load; (g) changing the AC potential of the second load terminal by connecting said terminal to any point of the unbalancing winding whereby an additional AC voltage superimposed on the DC voltage is introduced across the load, said AC voltage being changed as the second load terminal is connected to different points along the unbalancing winding; (h) coupling terminals of at least one capacitor with the transformer and rectifier circuit elements, so that one capacitor terminal is connected to the point of star connection of the transformer secondary, and the other terminal is connected to the same point of the rectifier system to which the first load terminal is connected, whereby the waveform of the AC component across the load is changed as capacitance of the capacitor increases.

Claim 24

A method for comprising the steps of: (a) supplying an at least one-phase AC voltage to a modifying transformer with star connected phase windings in the secondary; (b) modifying said AC voltage into a first, a second and a third voltage with the help of said transformer, the first voltage being an at least one-phase voltage and being created with the help of at least one ordinary winding of the secondary of said transformer, said first AC voltage being used for supplying an AC current to a system of rectifier circuit elements, the second voltage being an unbalancing voltage and being created by one of the ordinary phase windings which is also an unbalancing winding, the second voltage being used for changing the AC potential of one terminal of a load, the third voltage being another unbalancing voltage and being created by one of the ordinary phase windings which is also an unbalancing winding, the third voltage being used for changing the AC potential of the other terminal of the load; (c) rectifying said first voltage with the help of rectifying circuit elements for providing a rectified voltage across the load; (d) coupling a first load terminal with rectifier circuit elements and a second load terminal with a point of star connection of the secondary of the transformer, whereby a DC voltage with a minimal AC ripple voltage is introduced across the load; (e) changing the AC potential of the second load terminal by connecting said terminal to any point of the unbalancing winding, whereby an additional AC voltage superimposed on the DC voltage is introduced across the load, said AC voltage being changed as the second load terminal is connected to different points along the unbalancing winding; (f) changing the AC potential of the first load terminal by connecting one terminal of at least one capacitor to said first load terminal and connecting another capacitor terminal to any point of the unbalancing winding, this point being different from the point of connection of the second load terminal, whereby an additional AC voltage superimposed on the DC voltage is introduced across the load, said AC voltage being altered while said other capacitor terminal is connected to different points along the unbalancing winding.

Claim 25

A method for comprising the steps of: (a) supplying an at least one-phase AC voltage to a modifying transformer with star connected phase windings in the secondary; (b) modifying said AC voltage into a first, a second and a third voltage with the help of said transformer, the first voltage being an at least one-phase voltage and being created with the help of at least one ordinary winding of the secondary of said transformer, said first AC voltage being used for supplying an AC current to a system of rectifier circuit elements, the second voltage being an unbalancing voltage and being created by one of the ordinary phase windings which is also an unbalancing winding, the second voltage being used for changing the AC potential of one terminal of a load, the third voltage being another unbalancing voltage and being created by one of the ordinary phase windings which is also an unbalancing winding, the third voltage being used for changing the AC potential of the other terminal of the load; (c) rectifying said first voltage with the help of rectifying circuit elements for providing a rectified voltage across the load; (d) coupling a first load terminal with rectifier circuit elements and a second load terminal with a point of star connection of the secondary of the transformer, whereby a DC voltage with a minimal AC ripple voltage is introduced across the load; (e) changing the AC potential of the second load terminal by connecting said terminal to any point of the unbalancing winding, whereby an additional AC voltage superimposed on the DC voltage is introduced across the load, said AC voltage being changed as the second load terminal is connected to different points along the unbalancing winding; (f) changing the AC potential of the first load terminal by connecting one terminal of at least one capacitor to said first load terminal and connecting another capacitor terminal to any point of the unbalancing winding, this point being different from the point of connection of the second load terminal, whereby an additional AC voltage superimposed on the DC voltage is introduced across the load, said AC voltage being altered while said other capacitor terminal is connected to different points along the unbalancing winding.

Claim 26

A method for providing an AC voltage superimposed on a DC voltage, the method comprising the steps of: (a) supplying an at least one-phase AC voltage to a modifying transformer with electrically connected phase-windings in the secondary; (b) modifying said AC voltage into a first and a second voltage with the help of said transformer, the first voltage being an at least one-phase voltage and being created with the help of at least one ordinary winding of the secondary of said transformer, said first AC voltage being used for supplying an AC current to a system of rectifier circuit elements, the second voltage being an unbalancing voltage and being created by one of the ordinary windings which is also an unbalancing winding, the second voltage being used for changing the AC potential of one terminal of a load; (c) rectifying said first voltage with the help of rectifying circuit elements for providing a rectified voltage across the load; (d) coupling a first and a second load terminal with the system of rectifying circuit elements so that a DC voltage with a minimal AC ripple voltage is introduced across the load; (e) changing the AC potential of the first load terminal using at least one capacitor connected to the first load terminal with one capacitor terminal and to any point of the unbalancing winding with the other capacitor terminal, whereby an additional AC voltage superimposed on the DC voltage is introduced across the load, said AC voltage changing while said other capacitor terminal is connected to different points of the unbalancing winding.

Claim 27

A method for providing an AC voltage superimposed on a DC voltage, the method comprising the steps of: (a) supplying an at least one-phase AC voltage to a modifying transformer with electrically connected phase-windings in the secondary; (b) modifying said AC voltage into a first and a second voltage with the help of said transformer, the first voltage being an at least one-phase voltage and being created with the help of at least one ordinary winding of the secondary of said transformer, said first AC voltage being used for supplying an AC current to a system of rectifier circuit elements, the second voltage being an unbalancing voltage and being created by one of the ordinary windings which is also an unbalancing winding, the second voltage being used for changing the AC potential of one terminal of a load; (c) rectifying said first voltage with the help of rectifying circuit elements for providing a rectified voltage across the load; (d) coupling a first and a second load terminal with the system of rectifying circuit elements so that a DC voltage with a minimal AC ripple voltage is introduced across the load; (e) changing the AC potential of the first load terminal using at least one capacitor connected to the first load terminal with one capacitor terminal and to any point of the unbalancing winding with the other capacitor terminal, whereby an additional AC voltage superimposed on the DC voltage is introduced across the load, said AC voltage changing while said other capacitor terminal is connected to different points of the unbalancing winding.