Power factor corrected UPS with improved connection of battery to neutral
An uninterrupted power supply (UPS) device with uninterrupted neutral from input to output utilizes the same converter for converting rectified AC power and battery power to positive and negative high voltage (HV) rails. A simple circuit is utilized for connecting the battery to the conversion components of the PFC circuit without adverse affect on the performance of the PFC circuit, and while holding the battery substantially connected to neutral. In a first embodiment, the circuit comprises a simple combination of four diodes and a pair of high pass capacitors arranged so that in both power line and battery supply modes the battery is balanced around neutral. In a second, preferred embodiment, one terminal of the battery is connected directly to neutral.
1. An uninterrupted power supply (UPS), comprising:
first and second input terminals configured for connection to a power line source, the first input terminal configured for connection to a power line neutral;
first and second output terminals, the first output terminal being configured for connection to the first input terminal through an uninterrupted conductor;
a power factor correction (PFC) converter circuit configured to operate in an AC-powered mode as an AC to DC converter circuit, the PFC converter circuit having an input configured for connection to the first and second input terminals, a positive output terminal that produces a positive DC voltage, and a negative output terminal that produces a negative DC voltage;
a positive voltage rail connected to the positive output terminal;
a negative voltage rail connected to the negative output terminal;
a DC to AC converter circuit that has an input connected across the positive and negative voltage rails and that provides an AC output at the first and second output terminals; and
a connection circuit that connects a DC power source to the PFC converter circuit such that when the power line source fails and the UPS is in a DC-powered mode, voltage produced by the DC power source is converted through the PFC converter circuit to supply the positive and negative voltage rails.
2. An uninterrupted power supply (UPS) comprising:
first and second input terminals configured for connection to a power line source, the first input terminal configured for connection to a power line neutral;
first and second output terminals, the first output terminal configured to be connected to the first input terminal through an uninterrupted conductor;
a rectifier circuit connected to the first and second input terminals and operative to provide positive and negative rectified voltage outputs from the power line source;
a power factor correction (PFC) circuit having an input configured to be connected to the rectifier circuit and operative to provide positive and negative DC voltage outputs relative to the power line neutral from the positive and negative rectified voltage outputs;
a connection circuit operative to connect a terminal of a DC power source to the input of the PFC circuit such that, when the power line source fails, a DC voltage produced by the DC power source is convened through the PFC circuit to provide the positive and negative DC voltage outputs; and
a DC to AC converter circuit that produces an AC output at the first and second output terminals from the positive and negative DC outputs.
3. An uninterrupted power supply (UPS), comprising:
first and second input terminals;
first and second output terminals, the first output terminal conductively connected to the first input terminal;
a power factor correction (PFC) converter circuit configured to operate in an AC-powered mode as an AC to DC converter circuit, the PFC converter circuit having an input configured for connection to the first and second input terminals, a positive output terminal that produces a positive DC voltage, and a negative output terminal that produces a negative DC voltage;
a positive voltage rail connected to the positive output terminal;
a negative voltage rail connected to the negative output terminal;
a DC to AC converter circuit that has an input connected across the positive and negative voltage rails and that provides an AC output at the first and second output terminals; and
a connection circuit that connects a DC power source to the PFC converter circuit such that when an AC power source coupled to the first and second input terminal fails and the UPS is in a DC-powered mode, voltage produced by the DC power source is converted through the PFC converter circuit to supply the positive and negative voltage rails.
4. An uninterrupted power supply (UPS) comprising:
first and second input terminals;
first and second output terminals, the first output terminal conductively connected to the first input terminal;
a rectifier circuit connected to the first and second input terminals and operative to provide positive and negative rectified voltage outputs from an AC power source coupled to the first and second input terminals;
a power factor correction (PFC) circuit having an input configured to be connected to the rectifier circuit and operative to provide positive and negative DC voltage outputs;
a connection circuit operative to connect a terminal of a DC power source to the input of the PFC circuit such that, when the AC power source fails, a DC voltage produced by the DC power source is converted through the PFC circuit to provide the positive and negative DC voltage outputs; and
a DC to AC converter circuit that produces an AC output at the first and second output terminals from the positive and negative DC outputs.