Abstract: A switch mode power converter achieving high efficiency through zero voltage switching (ZVS) by using an auxiliary switch, a capacitor, an auxiliary winding and an inductor. The technique can be applied to a boost, buck-boost, buck, isolated forward or isolated flyback converter. The auxiliary switch is turned on before the main power switch turns on, and the capacitor provides voltage to energize the inductor and force current to flow into the auxiliary winding. The current is transformed by the main winding and discharges the capacitance across main power switch to zero volts before the main switch turns on. Hence ZVS is obtained and can greatly reduce the switching loss of the main power switch.

Abstract: An AC-to-DC power converter draws input current through an inductor. When the input voltage of the converter is sufficiently high and the switch of the converter is on, current flows into the converter, through the inductor, to the tap of a transformer, through a first primary winding of the transformer, and through the switch. When the switch is then turned off, current continues to flow through the inductor and to the tap of the transformer but then flows through a second primary of the transformer and into a storage capacitor. Energy stored in the storage capacitor is transferred to the load when it is not possible to obtain sufficient energy from the input current to supply the load. The AC-to-DC converter has very few circuit components and low input current harmonics.

Abstract: A buck converter in accordance with the present invention provides multiple, well regulated, low voltage outputs. A cascaded buck converter comprises a main buck converter that is coupled to a subordinate buck converter through a cascade transistor in series with the free wheeling diode or transistor. The main buck converter is coupled to the free wheeling diode through the cascade transistor. Additional voltage outputs are possible by placing additional subordinate buck converters in series with the cascade transistor.An isolated forward converter with multiple output voltages in accordance with the present invention may be derived using the cascaded buck converter topology. The cascading configuration permits multiple voltage outputs using a minimum number of switching devices while avoiding undesirable cross regulation.

Abstract: A switch mode power converter achieving high efficiency through zero voltage switching (ZVS) by using an auxiliary switch, a capacitor, an auxiliary winding and an inductor. The technique can be applied to a boost, buck-boost, buck, isolated forward or isolated flyback converter. The auxiliary switch is turned on before the main power switch turns on, and the capacitor provides voltage to energize the inductor and force current to flow into the auxiliary winding. The current is transformed by the main winding and discharges the capacitance across main power switch to zero volts before the main switch turns on. Hence ZVS is obtained and can greatly reduce the switching loss of the main power switch.

Abstract: A transformer bobbin has margining ledges disposed on either side of a primary winding surface such that a primary wire is wound between margining surfaces of the margining ledges. L-shaped grooves extend into the margining ledges and then parallel to the primary winding surface to accommodate the primary wire ends that connect to terminals of the bobbin. Margining of the secondary is accomplished with a pair of margining bibs which attach to the bobbin after the primary is wound and after a layer of insulation is placed over the primary. The secondary is wound over the insulation layer between margining surfaces of the bibs. With the margining ledges and bibs, required creepage distances can be maintained without the use of sleeving, margining tape, interlayer tape or holding tape.

Abstract: An AC-to-DC power converter achieves greater than 80 percent power factor correction with greater than 75 percent efficiency using only one power switch, only one magnetic component, only one control loop, and a storage capacitor. The only magnetic component is a transformer having first primary winding, a second primary winding, and at least one secondary winding. During a first time interval of the period of the AC input current, the second primary winding is energized with energy previously stored in a storage capacitor. During a second time interval of the period of the AC input current, the first primary winding is energized with energy of an input current flowing through the AC input terminals. As a result, the AC-to-DC power converter drawns input current for an extended period of time before the point in time when the input voltage peaks and also for an extended period of time after the point in time when the input voltage peaks.

Abstract: An AC-to-DC power converter achieves greater than 80 percent power factor correction with greater than 75 percent efficiency using only one power switch, only one magnetic component, only one control loop, and a storage capacitor. The only magnetic component is a transformer having first primary winding, a second primary winding, and at least one secondary winding. During a first time interval of the period of the AC input current, the second primary winding is energized with energy previously stored in a storage capacitor. During a second time interval of the period of the AC input current, the first primary winding is energized with energy of an input current flowing through the AC input terminals. As a result, the AC-to-DC power converter drawns input current for an extended period of time before the point in time when the input voltage peaks and also for an extended period of time after the point in time when the input voltage peaks.

Abstract: An AC-to-DC power converter achieves greater than 80 percent power factor correction with greater than 75 percent efficiency using only one power switch, only one magnetic component, only one control loop, and a storage capacitor. The only magnetic component is a transformer having first primary winding, a second primary winding, and at least one secondary winding. During a first time interval of the period of the AC input current, the second primary winding is energized with energy previously stored in a storage capacitor. During a second time interval of the period of the AC input current, the first primary winding is energized with energy of an input current flowing through the AC input terminals. As a result, the AC-to-DC power converter drawns input current for an extended period of time before the point in time when the input voltage peaks and also for an extended period of time after the point in time when the input voltage peaks.

Abstract: A boost converter power supply circuit uses energy from a diode recovery current which flows in the blocking diode at diode commutation to discharge a capacitance associated with the main switch of the boost converter in order to achieve zero voltage switching. The diode recovery current energy is initially captured in an inductor, is then transferred to a capacitor, and is then transferred back to the inductor prior to the main switch being switched on. In accordance with another embodiment, a control circuit for controlling a boost converter to achieve power factor correction is disclosed which does not use a high gain input current feedback loop. The control circuit responds relatively quickly to output load changes, thereby overcoming disadvantages of prior art control circuits. Because the control circuit does not require an X-Y multiplier, the control circuit lends itself to realization in integrated circuit form.

Abstract: A two switch, DC/DC converter provides sufficient inductive energy storage at the termination of the "on" period of each switch to alter the charge on the intrinsic and stray capacitance of the combination of switches producing zero voltage across the alternate switch prior to its turn on. A short dead-band between the turn on pulses provided by the control circuit allows time for this transition. Thus the energy stored in the capacitance of the switches is returned to the source and load rather than being dissipated in the switching devices. This greatly improves the efficiency of the converter particularly when operating at high frequency. The unique topology of the converter provides other new and useful characteristics in addition to zero voltage switching capability such as operation as constant frequency with pulse-width-modulation for regulation, quasi-square wave output current, and the ability to integrate the magnetic elements with or without coupling.

Abstract: A two switch, DC/DC converter provides sufficient inductive energy storage at the termination of the "on" period of each switch to alter the charge on the intrinsic and stray capacitance of the combination of switches producing zero voltage across the alternate switch prior to its turn on. A short dead-band between the turn on pulses provided by the control circuit allows time for this transition. Thus the energy stored in the capacitance of the switches is returned to the source and load rather than being dissipated in the switching devices. This greatly improves the efficiency of the converter particularly when operating at high frequency. The unique topology of the converter provides other new and useful characteristics in addition to zero voltage switching capaibility such as operation at constant frequency with pulse-width-modulation for regulation, quasi-square wave output current, and the ability to integrate the magnetic elements with or without coupling.

Abstract: An EMI/RFI shielded housing for an electrical apparatus comprises a case member and a complementary cover member, each comprising an end wall portion and a side wall portion together defining substantially continuous and unbroken peripheral surfaces. The side wall portions of these members are respectively configured for an interference fit therebetween to define an assembled condition of the housing. This interference fit is defined by the side wall portion of the case member being received interiorally of the side wall portion of the cover member. Moreover, substantially the entire inner surfaces of the end wall portions of both case and cover member are electrically conductive, substantially the entire inner surface of the side wall portion of the case member is electrically conductive and major fractional portions of respective facing surfaces of the assembled and interference-fitted side wall portions are electrically conductive.