Abstract: A switch mode power supply is described including a primary side for coupling to a mains supply and a secondary side for coupling to a device, an isolation transformer comprising a primary coil and a secondary coil and arranged to isolate the primary side from the secondary side, and a noise filter coupled between a primary ground at the primary side and a secondary ground at the secondary side, the noise filter having a conductance value that varies with frequency. The noise filter conductance comprises a peak conductance in a peak conductance frequency region. The noise filter is operable to reduce the common-mode noise of the switch mode power supply at frequencies occurring in the peak conductance frequency region.

Abstract: A switch mode power supply is described including a primary side for coupling to a mains supply and a secondary side for coupling to a device, an isolation transformer comprising a primary coil and a secondary coil and arranged to isolate the primary side from the secondary side, and a noise filter coupled between a primary ground at the primary side and a secondary ground at the secondary side, the noise filter having a conductance value that varies with frequency. The noise filter conductance comprises a peak conductance in a peak conductance frequency region. The noise filter is operable to reduce the common-mode noise of the switch mode power supply at frequencies occurring in the peak conductance frequency region.

Abstract: A transformer (900) comprising a primary-side auxiliary winding (976, wherein in use the primary-side auxiliary winding (976) is configured such that a first electric potential distribution is induced in the primary-side auxiliary winding (976); and a secondary-side auxiliary winding (982) configured such that a second electric potential distribution is induced in the secondary-side auxiliary winding (982). The primary-side auxiliary winding (976) is physically located between (a) a main pair of windings; and (b) the second-side auxiliary winding (982).

Abstract: A transformer (900) comprising a primary-side auxiliary winding (976, wherein in use the primary-side auxiliary winding (976) is configured such that a first electric potential distribution is induced in the primary-side auxiliary winding (976); and a secondary-side auxiliary winding (982) configured such that a second electric potential distribution is induced in the secondary-side auxiliary winding (982). The primary-side auxiliary winding (976) is physically located between (a) a main pair of windings; and (b) the second-side auxiliary winding (982).

Abstract: The invention relates to a switched mode power converter and a method of operating such a converter A switched mode power converter according to the invention includes a transformer (2) having a primary winding (2a) and at least one secondary winding (2b) and a secondary side rectifier circuit including an output filter (6, 10) coupled to the at least one secondary winding (2b), and a secondary side active switch device (S3) coupled between the at least one secondary winding and the output filter. The converter further includes primary side and secondary side control means (12, 16, 18) for regulating the switching of the primary side and secondary side switches, respectively, and configured so as to reduce the duty cycle of the primary side switch device (S1) during a lower power mode of operation of the converter, the reduction of the duty cycle of the primary side switch being determined with reference to the duty cycle of the secondary side switch (S3).

Abstract: In order to improve the efficiency of a Power Factor Convertor (PFC) first stage to a AC-DC converter the switching cell is split into two smaller ones (each comprising a switched inductor with an output diode). Below a certain load only one cell is active. The second cell only becomes active, out of phase with the first, but not generally in antiphase, after a predefined load level is surpassed in such a way that above that level the first cell has a fixed on time and the second cell a variable one.

Abstract: A switched mode power converter is provided which includes a transformer (2) having a primary winding (2a) and at least one secondary winding (2b); a primary side active switch device (S1) coupled to the primary winding for selectively applying an input voltage to the primary winding; and a secondary side rectifier circuit including an output filter (6, 12) coupled to the at least one secondary winding (2), and first and second active switch devices (16, 14) coupled between the at least one secondary winding (2b) and the output filter. The switch devices are arranged such that each one is operable independently of the other to block current between the at least one secondary winding and the output filter in an opposite direction to the other. This facilitates better regulation of the converter and avoids the occurrence of voltage spikes encountered in existing configurations.

Abstract: In order to improve the efficiency of a Power Factor Convertor (PFC) first stage to a AC-DC converter the switching cell is split into two smaller ones (each comprising a switched inductor with an output diode). Below a certain load only one cell is active. The second cell only becomes active, out of phase with the first, but not generally in antiphase, after a predefined load level is surpassed in such a way that above that level the first cell has a fixed on time and the second cell a variable one.

Abstract: In a multi-resonance converter for converting a first DC voltage into a second DC voltage, wherein the output of a half-bridge comprising semiconductor switches is connected through a resonance capacitor to the primary winding of a transformer and the secondary winding of the transformer, together with rectifier elements, an output inductor and an output capacitor, forms a current output, it is proposed that a controller, which can be supplied which the voltage across the output capacitor and a reference voltage, should control the semiconductor switches alternately so that one of the semiconductor switches is respectively turned on at a predetermined time after the other semiconductor switch is turned off. Preferably, the frequency is controlled in an upper range of the drawn power while in a lower range of the drawn power, the mark-space ratio is controlled for selected respectively constant frequencies.

Abstract: A switched mode power converter is provided which includes a transformer (2) having a primary winding (2a) and at least one secondary winding (2b); a primary side active switch device (S1) coupled to the primary winding for selectively applying an input voltage to the primary winding; and a secondary side rectifier circuit including an output filter (6, 12) coupled to the at least one secondary winding (2), and first and second active switch devices (16, 14) coupled between the at least one secondary winding (2b) and the output filter. The switch devices are arranged such that each one is operable independently of the other to block current between the at least one secondary winding and the output filter in an opposite direction to the other. This facilitates better regulation of the converter and avoids the occurrence of voltage spikes encountered in existing configurations.

Abstract: The invention relates to a switched mode power converter and a method of operating such a converter A switched mode power converter according to the invention includes a transformer (2) having a primary winding (2a) and at least one secondary winding (2b) and a secondary side rectifier circuit including an output filter (6, 10) coupled to the at least one secondary winding (2b), and a secondary side active switch device (S3) coupled between the at least one secondary winding and the output filter. The converter further includes primary side and secondary side control means (12, 16, 18) for regulating the switching of the primary side and secondary side switches, respectively, and configured so as to reduce the duty cycle of the primary side switch device (S1) during a lower power mode of operation of the converter, the reduction of the duty cycle of the primary side switch being determined with reference to the duty cycle of the secondary side switch (S3).

Abstract: In a multi-resonance converter for converting a first DC voltage into a second DC voltage, wherein the output of a half-bridge comprising semiconductor switches is connected through a resonance capacitor to the primary winding of a transformer and the secondary winding of the transformer, together with rectifier elements, an output inductor and an output capacitor, forms a current output, it is proposed that a controller, which can be supplied which the voltage across the output capacitor and a reference voltage, should control the semiconductor switches alternately so that one of the semiconductor switches is respectively turned on at a predetermined time after the other semiconductor switch is turned off. Preferably, the frequency is controlled in an upper range of the drawn power while in a lower range of the drawn power, the mark-space ratio is controlled for selected respectively constant frequencies.