Device for reducing the leakage noise of a power converter

Claim 1

A device for reducing the leakage noise of a power converter, comprising: AC power path means for transmitting an AC signal, having at least two lines adapted to be coupled to a source of AC power at one end of each said line; first noise filter means for preventing radio frequency noise produced in said power converter from leaking externally through said AC power path means, and having: (a) two inductors connected in series to the other ends of said lines of said AC power path means, the first and second terminals of each said inductor forming input and output terminals of said first noise filter means, respectively, (b) a ferrite core, said two inductors being coupled together by said ferrite core, (c) at least one capacitor, and (d) two ground capacitors, each said ground capacitor connected in parallel between one of the first and second terminals of each said inductor and ground; a rectifier circuit coupled to the output terminals of said first noise filter means, including at least one diode means for rectifying said AC signal transmitted from said AC power path means through said first noise filter means, to thereby produce a rectified DC voltage including a ripple component of said AC signal as an output signal; second noise filter means for preventing radio frequency noise produced in said power converter from being reflected from the power converter to the outside through said AC power path means, and having: (a) two inductors connected in series to said output signal of said rectifier circuit, the terminals of each said inductor forming input and output terminals of said second noise filter means, (b) a ferrite core, said inductors being coupled together by said ferrite core, and (c) at Ieast one capacitor; smoothing circuit means for smoothing a ripple component of said AC signal included in said rectified DC voltage which is supplied from said rectifier circuit means through said second noise filter means, to thereby produce an output of a DC signal; and an inverter circuit having a plurality of semiconductor switching means for converting said DC signal supplied from said smoothing circuit means into an output AC signal of a predetermined frequency, the inductances and capacitances of said two inductors and said at least one capacitor of said second noise filter means having values selected so as to reduce the radio frequency noise produced in said inverter circuit below the level to which the radio frequency noise can be reduced by said first noise filter means, and the inductances and capacitances of said two inductors, said at least one capacitor and said two ground capacitors of said first noise filter means having values selected so as to reduce the radio frequency noise coming from said inverter circuit after being reduced by said second noise filter means and the radio frequency noise produced in said rectifier circuit to a practically negligible level.

Claim 2

A device for reducing the leakage noise of a power converter, comprising: AC power path means for transmitting an AC signal, having at least two lines adapted to be coupled to a source of AC power at one end of each said line; first noise filter means for preventing radio frequency noise produced in said power converter from leaking externally through said AC power path means, and having: (a) two inductors connected in series to the other ends of said lines of said AC power path means, the first and second terminals of each said inductor forming input and output terminals of said first noise filter means, respectively, (b) a ferrite core, said two inductors being coupled together by said ferrite core, (c) at least one capacitor, and (d) two ground capacitors, each said ground capacitor connected in parallel between one of the first and second terminals of each said inductor and ground; a rectifier circuit coupled to the output terminals of said first noise filter means, including at least one diode means for rectifying said AC signal transmitted from said AC power path means through said first noise filter means, to thereby produce a rectified DC voltage including a ripple component of said AC signal as an output signal; second noise filter means for preventing radio frequency noise produced in said power converter from being reflected from the power converter to the outside through said AC power path means, and having: (a) two inductors connected in series to said output signal of said rectifier circuit, the terminals of each said inductor forming input and output terminals of said second noise filter means, (b) a ferrite core, said inductors being coupled together by said ferrite core, and (c) at Ieast one capacitor; smoothing circuit means for smoothing a ripple component of said AC signal included in said rectified DC voltage which is supplied from said rectifier circuit means through said second noise filter means, to thereby produce an output of a DC signal; and an inverter circuit having a plurality of semiconductor switching means for converting said DC signal supplied from said smoothing circuit means into an output AC signal of a predetermined frequency, the inductances and capacitances of said two inductors and said at least one capacitor of said second noise filter means having values selected so as to reduce the radio frequency noise produced in said inverter circuit below the level to which the radio frequency noise can be reduced by said first noise filter means, and the inductances and capacitances of said two inductors, said at least one capacitor and said two ground capacitors of said first noise filter means having values selected so as to reduce the radio frequency noise coming from said inverter circuit after being reduced by said second noise filter means and the radio frequency noise produced in said rectifier circuit to a practically negligible level.

Claim 6

A device for reducing the leakage noise of a power converter, comprising: an AC power path means for transmitting an AC signal, having at least two lines adapted to be coupled to a source of AC power; a first noise filter for preventing radio frequency noise produced in said power converter from leaking externally through said AC power path means, and having (a) two inductors, connected in series to said AC power path means so that the terminals of each said inductor form input and output terminals of said first noise filter means, (b) a ferrite core, said two inductors being coupled together by said ferrite core, and (c) at least one capacitor; a rectifier circuit connected to the output terminals of said first noise filter means including at least one diode means for rectifying said AC signal transmitted from said AC power path means through said first noise filter to produce a DC rectified voltage including a ripple component of said AC signal, as an output signal; a second noise filter for preventing radio frequency noise produced in said power converter from leaking externally through said AC power path means, and having: (a) two inductors connected in series to said output signal of said rectifier circuit so that the terminals of said inductors form input and output terminals of said second noise filter, (b) a ferrite core, said two inductors being coupled together by said ferrite core, (c) at least one capacitor, and (d) two ground capacitors, each said ground capacitor connected in parallel between one of the input and output terminals of each said inductor of said second noise filter and ground; smoothing circuit means for smoothing a ripple component of said AC signal included in said rectified DC voltage which is supplied from said rectifier circuit means through said second noise filter means, to hereby output a DC signal; an invertor circuit having a plurality of semiconductor switching elements for converting said DC signal supplied from said smoothing circuit means into an AC signal of a predetermined frequency; the inductances and capacitances of said two inductors, said at least one capacitor and said two ground capacitors of said second noise filter having values selected so as to reduce the radio frequency noise produced in said inverter circuit below the level to which the radio frequency noise can be reduced by said first noise filter, and the inductance and capacitance values of said two inductors and said at least one capacitor of said first noise filter being selected to reduce the noise coming from said inverter circuit after being reduced by said second noise filter and the radio frequency noise produced in said rectifier circuit to a substantially negligible level.

Claim 7

A device for reducing the leakage noise of a power converter, comprising: an AC power path means for transmitting an AC signal, having at least two lines adapted to be coupled to a source of AC power; a first noise filter for preventing radio frequency noise produced in said power converter from leaking externally through said AC power path means, and having (a) two inductors, connected in series to said AC power path means so that the terminals of each said inductor form input and output terminals of said first noise filter means, (b) a ferrite core, said two inductors being coupled together by said ferrite core, and (c) at least one capacitor; a rectifier circuit connected to the output terminals of said first noise filter means including at least one diode means for rectifying said AC signal transmitted from said AC power path means through said first noise filter to produce a DC rectified voltage including a ripple component of said AC signal, as an output signal; a second noise filter for preventing radio frequency noise produced in said power converter from leaking externally through said AC power path means, and having: (a) two inductors connected in series to said output signal of said rectifier circuit so that the terminals of said inductors form input and output terminals of said second noise filter, (b) a ferrite core, said two inductors being coupled together by said ferrite core, (c) at least one capacitor, and (d) two ground capacitors, each said ground capacitor connected in parallel between one of the input and output terminals of each said inductor of said second noise filter and ground; smoothing circuit means for smoothing a ripple component of said AC signal included in said rectified DC voltage which is supplied from said rectifier circuit means through said second noise filter means, to hereby output a DC signal; an invertor circuit having a plurality of semiconductor switching elements for converting said DC signal supplied from said smoothing circuit means into an AC signal of a predetermined frequency; the inductances and capacitances of said two inductors, said at least one capacitor and said two ground capacitors of said second noise filter having values selected so as to reduce the radio frequency noise produced in said inverter circuit below the level to which the radio frequency noise can be reduced by said first noise filter, and the inductance and capacitance values of said two inductors and said at least one capacitor of said first noise filter being selected to reduce the noise coming from said inverter circuit after being reduced by said second noise filter and the radio frequency noise produced in said rectifier circuit to a substantially negligible level.