Abstract: A power supply for a negative voltage load has a switch-mode power unit, a monitoring unit, a first auxiliary power unit and a second auxiliary power unit. The switch-mode power unit has a rectifying circuit, a power factor correction circuit, a DC to DC power circuit. The first auxiliary power unit is connected to output terminals of the power factor correction circuit and converts DC power to a first DC power for driving the monitoring unit. The second auxiliary power unit is connected to the negative voltage load in parallel and converts negative power from the negative voltage load to a second DC power for driving the monitoring unit when AC power is interrupted. Since the first and the second auxiliary power unit do not work at the same time, the power supply can effectively enhances the conversion efficiency of the power supply.

Abstract: A resonant circuit has two parallel resonant branches and one assistant inductor connecting the two resonant branches. Each resonant branch has a series capacitor and a series inductor connected in series. The other end of the series inductor is for connecting to a primary side of a transformer unit. The resonant circuit can provide two characteristic resonant frequencies fr and fm, so that a resonant power converter using the resonant circuit has an operating frequency fs that satisfies fs>fr or fm<fs<fr. The combination of the two resonant branches and the assistant inductor can reduce the frequency switch range of the resonant power converter within a specific voltage gain.

Abstract: A power supply for a negative voltage load has a switch-mode power unit, a monitoring unit, a first auxiliary power unit and a second auxiliary power unit. The switch-mode power unit has a rectifying circuit, a power factor correction circuit, a DC to DC power circuit. The first auxiliary power unit is connected to output terminals of the power factor correction circuit and converts DC power to a first DC power for driving the monitoring unit. The second auxiliary power unit is connected to the negative voltage load in parallel and converts negative power from the negative voltage load to a second DC power for driving the monitoring unit when AC power is interrupted. Since the first and the second auxiliary power unit do not work at the same time, the power supply can effectively enhances the conversion efficiency of the power supply.

Abstract: A fan includes a motor and an impeller. The motor drives the impeller to rotate and includes a base, a bearing, a stator, a rotor and a magnetic element. The central portion of the base is extended to form a bushing for accommodating the bearing therein. The stator telescopes around the bushing. The rotor is disposed corresponding to the stator and has a shaft passing through the bearing. The magnetic element is disposed at the bottom of the bushing and located adjacent to one end of the shaft.

Abstract: A resonant circuit has two parallel resonant branches and one assistant inductor connecting the two resonant branches. Each resonant branch has a series capacitor and a series inductor connected in series. The other end of the series inductor is for connecting to a primary side of a transformer unit. The resonant circuit can provide two characteristic resonant frequencies fr and fm, so that a resonant power converter using the resonant circuit has an operating frequency fs that satisfies fs>fr or fm<fs<fr. The combination of the two resonant branches and the assistant inductor can reduce the frequency switch range of the resonant power converter within a specific voltage gain.

Abstract: A fan includes a motor and an impeller. The motor drives the impeller to rotate and includes a base, a bearing, a stator, a rotor and a magnetic element. The central portion of the base is extended to form a bushing for accommodating the bearing therein. The stator telescopes around the bushing. The rotor is disposed corresponding to the stator and has a shaft passing through the bearing. The magnetic element is disposed at the bottom of the bushing and located adjacent to one end of the shaft.