Abstract: An AC/DC/AC power converter is constructed without using any electrolytic capacitor, such that it is more compact, durable and reliable. This converter only required a small capacitance for its DC link and this capacitor can be easily obtainable with other types of capacitors such as film or ceramic type. The system further includes means to disconnect both input and output to this DC bus capacitor. A controller capable of fast monitoring the DC bus voltage is also able of quickly disconnecting the capacitor out of either input or output energy path to prevent the capacitor from being charged to over-voltage. The controller also possesses capability of re-connecting the disrupted energy path once the DC bus voltage returns to normal.

Abstract: An AC/DC/AC power converter is constructed without using any electrolytic capacitor, such that it is more compact, durable and reliable. This converter only required a small capacitance for its DC link and this capacitor can be easily obtainable with other types of capacitors such as film or ceramic type. The system further includes means to disconnect both input and output to this DC bus capacitor. A controller capable of fast monitoring the DC bus voltage is also able of quickly disconnecting the capacitor out of either input or output energy path to prevent the capacitor from being charged to over-voltage. The controller also possesses capability of re-connecting the disrupted energy path once the DC bus voltage returns to normal.

Abstract: A portable outdoor stove is provided which includes a burner primarily comprising an outer and inner pieces bolted tightly to form a small gas/air mixture chamber for accepting and maintaining high pressure gaseous fuel, a wind guard of cylinder shape capable of tightly coupled with a cooking vessel and possessing window opening of less than 180° toward its top for exhaust outlet, adjustable means for supporting the burner and positioning flame from burner onto bottom of cooking vessel and supporting means for the wind guard.

Abstract: An active filter controller for use with both pure and hybrid shunt filters wherein the controller maintains a minimum DC bus voltage required to generate a compensating current on coupling lines and also extrapolates to estimate an expected feedback current to be compensated so that compensation currents are more accurate and harmonic currents are appreciably reduced.

Abstract: The burner possesses set of holes capable of directing high pressure combustion flame toward a upper center point concentrating heating power, extremely suitable for heating the bottom of a wok or any round bottom cooking vessel. With an adapter, another set of holes is capable of producing upward and outward spreading flame for flat bottom type cooking vessels. A protection guard can be put around the first wind guard preventing an operator accidentally touching the wind guard during cooking.

Abstract: A harmonic mitigating apparatus connected between a three phase power source and a load provides a multiple-winding reactor for reducing harmonics directed from the load to the source, the apparatus including, for each system phase, first and second line windings in series between the source and load and oriented so as to have the same polarity such that the winding fluxes add thereby increasing total reactance to harmonics directed from the load to the supply, the apparatus also including at least one trap circuit including a series inductance and capacitor for each phase and linked between the first and second line windings and a neutral point (or another phase), the trap circuit characterized by a reactance that is lower than the reactance of the first line winding such that harmonics flow into the trap circuit, for each phase, at least two of the first and second line windings and the trap winding arranged on the same core.

Abstract: An active filter controller for use with both pure and hybrid shunt filters wherein the controller maintains a minimum DC bus voltage required to generate a compensating current on coupling lines and also extrapolates to estimate an expected feedback current to be compensated so that compensation currents are more accurate and harmonic currents are appreciably reduced.

Abstract: A harmonic mitigating apparatus connected between a three phase power source and a load provides a multiple-winding reactor for reducing harmonics directed from the load to the source, the apparatus including, for each system phase, first and second line windings in series between the source and load and oriented so as to have the same polarity such that the winding fluxes add thereby increasing total reactance to harmonics directed from the load to the supply, the apparatus also including at least one trap circuit including a series inductance and capacitor for each phase and linked between the first and second line windings and a neutral point (or another phase), the trap circuit characterized by a reactance that is lower than the reactance of the first line winding such that harmonics flow into the trap circuit, for each phase, at least two of the first and second line windings and the trap winding arranged on the same core.

Abstract: A nine-phase AC to DC power converter system may exhibit current unbalance problem among bridges due to two reasons: slight voltage magnitude difference among different sets of three-phase supplies and pre-existing voltage harmonics in the power supply lines. Since the unpredictability of the pre-existing harmonics and manufacturing uncertainty of the nine-phase power supply (it is usually a three to nine phase transformer), all devices in the rectifier bridges are required to carry much higher than necessary current magnitude and have to be designed oversize, as much as 100% up. Here we describe various topologies of harmonic blocking reactors to combat this problem. The described topologies can significantly improve this situation and thus avoid the over-sizing exercise (cost) when such converter system is built. The principle can be easily extended to any multi-phase AC to DC or DC to AC power conversion system of more than nine phases.

Abstract: The invention includes an autotransformer for converting three-phase AC power to nine-phase AC power. The autotransformer includes three coils, each coil including a plurality of serial windings that together form a polygon. Nine output nodes are provided between adjacent winding pairs, the windings sized and arranged such that adjacent output voltages are separated by 40 degree phase shift and such that output voltage magnitudes are essentially identical. Both step-down and unity gain input node sets are provided wherein, when three-phase AC supply lines are linked to the step-down input set the output voltage is stepped down and when the three-phase AC supply lines are linked to the unity gain input set the transformer gain is unity. The invention also includes an isolation transformer having characteristics similar to those of the autotransformer.

Abstract: The invention includes a transformer for converting three-phase AC power to nine-phase AC power. An autotransformer includes three coils, each coil including a plurality of serial windings that together form a polygon. Nine output nodes are provided between adjacent winding pairs, the windings sized and arranged such that adjacent output voltages are separated by 40 degree phase shift and such that output voltage magnitudes are essentially identical. Both step-up and unity gain input node sets are provided wherein, when three phase AC supply lines are linked to the step-up input set the output voltage is stepped up and when the three phase AC supply lines are linked to the unity gain input set the transformer gain is unity. An isolation transformer includes a secondary arranged like the autotransformer configuration described above.

Abstract: The invention includes an autotransformer for converting three-phase AC power to twelve-phase AC power using only three coils (e.g., no primary or dead windings are required). The autotransformer includes three coils, each coil including a plurality of serial windings that together form a polygon. Twelve output nodes are provided between adjacent winding pairs, the windings sized and arranged such that adjacent output voltages are separated by 30 degree phase shift and such that output voltage magnitudes are essentially identical. In some embodiments step-up, step-down and unity gain input node sets are provided while in other embodiments unity gain and either step-up or step-down input node sets are provided. The invention also includes an isolation transformer configuration that uses a secondary configuration that is identical to inventive autotransformer configurations.