Two-stage converter using low permeability magnetics
View Patent ↗The use of low permeability magnetic material (NSME) with the disclosed design strategies form a two-stage isolated output converter system with the distinct advantages of superior density, efficiency, thermal operating bandwidth, service life, transient survival, and form factor flexibility over the prior art. These improvements are realized by, optimized application of NSME, efficient rectifying flyback management techniques, inclusion of switching buffers that substantially reduce switching losses. The instant invention provides power factor correction, output regulation, inrush limiting, over voltage, over current, over temperature, and transient protection, multi-converter load sharing, hot swapability, and fault signals. The disclosed system is designed, specified, and certified to function from −40 deg. C. to +65 deg. C. from a 180 vac to 264 vac 50/60 Hz input line and supports 1000 watts of output or 600 watts from 90 vac to 120 vac 50/60 Hz line input at greater then 0.95 power factor and features a packaged power density of 14 watts per cu. in. at high line.
1. A two stage converter comprising:
a power factor corrected flyback converter (PFCFC) having a feedback circuit connecting a boosted DC output to a power factor controller;
said power factor corrected flyback converter further comprising a magnetic element operating in a non-saturated region (NSME);
said PFCFC having a zero hold time silicon carbide diode in parallel with a high speed flyback diode;
an AC input comprising an inrush limiter, line filter rectifier and a transient protection diode which feeds an input to the PFCFC;
a buffer circuit providing a low impedance gate drive to a main switch transistor of the PFCFC; and
said PFCFC having a regulated DC output to an inrush controller;
an inrush controller sub-circuit having an input from a thermal switch which functions to provide an over-temperature shutdown;
said inrush controller having an output to a push pull converter;
said push pull converter having a controller which provides a duty cycle and frequency;
said push pull converter having a rectifier circuit;
said power factor corrected flyback converter providing a variable DC signal to said push pull converter;
said push pull converter further comprising a magnetic element operating in a non-saturating region (NSME).
2. A single stage converter comprising:
a power factor corrected flyback converter (PFCFC) having a feedback circuit connecting a boosted DC output to a power factor controller;
said power factor corrected flyback converter further comprising a magnetic element operating in a non-saturated region (NSME);
said PFCFC having a zero hold time silicon carbide diode in parallel with a high speed flyback diode;
an AC input comprising a line filter rectifier and a transient protection diode which feeds an input to the PFCFC;
a control power sub-circuit having an input from an auxiliary winding of the NSME;
said control power sub-circuit having an output to a thermal switch which functions to provide an over-temperature shutdown;
said thermal switch having an output to a buffer circuit;
said buffer circuit provides a low impedance gate drive to a main switch transistor of the PFCFC; and
said PFCFC having a regulated DC output.
3. The converter of claim 2 , wherein said NSME further comprises a low permeability.
4. The converter of claim 3 , wherein the NSME further comprises a mixture of 85% by weight of iron, 6% by weight of aluminum, and 9% by weight of silicon, thereby providing a wide thermal operating range for the magnetic element.
5. The converter of claim 2 , wherein the low permeability has a range of one to 500u.
6. The converter of claim 4 , wherein the NSME is an air magnetic element.
7. The converter of claim 2 , wherein the NSME further comprises a B-H curve characteristic ranging from B=1 to 10,000 gauss and H=1 to 100 oersteds.
8. The converter of claim 2 further comprising a frequency modulating circuit to optimize an output signal from the NSME.
9. The converter of claim 8 , wherein said converter is a push pull converter and further comprises a double-ended controller having a fixed pulse width.
10. The converter of claim 8 , wherein said converter is a push pull converter and further comprises a double-ended controller having a variable frequency.
11. The converter of claim 8 , wherein said converter is a push pull converter and further comprises a double ended controller having a duty cycle ranging from 40% to 60% of a fixed pulse width.
12. The converter of claim 11 , wherein the duty cycle is 50%.
13. The converter of claim 8 , wherein said converter is a push pull converter and further comprises a double-ended controller having an optimizing circuit varying a relationship between pulse width and frequency.
14. The converter of claim 2 , wherein said converter has a variable duty cycle.
15. The converter to claim 2 , wherein said converter has a constant duty cycle.
16. The converter of claim 2 further comprising a control circuit to monitor a bias of the NSME and controls a frequency and a pulse width for optimizing a NSME efficiency.
17. The converter of claim 2 , wherein the NSME is selected from the group consisting of:
an air magnetic element;
a molypermalloy powder(MPP) magnetic element;
a high flux MPP magnetic element;
a powder magnetic element;
a gapped ferrite magnetic element;
a tape wound magnetic element;
a cut magnetic element;
a laminated magnetic element; and
an amorphous magnetic element.