Non-isolated bus converters with voltage divider topology

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United States Patent and Trademark Office

A voltage converter having four switches Q1, Q2, Q3, Q4, connected in series and operated in pairs in a complementary fashion. An input voltage is provided across the four switches. A middle capacitor is connected in parallel with two middle switches Q2, Q3. Voltage output is provided across switches Q3 and Q4 (i.e. at a midpoint of the four switches). Series-connected output capacitors can be connected in parallel with the set of four switches. The middle capacitor alone or in combination with parallel connected capacitors, when connected to the input voltage or output terminals functions as a capacitive voltage divider for voltage conversion and/or regulation with extremely high efficiency and which can provide either step-down or step-up function. Also, an output inductor can be provided as a perfecting feature to further increase efficiency. Alternatively, two of the four switches can be replaced with rectifying diodes. Alternatively, the voltage converter has two or more sets of four switches connected in parallel. The two sets can be connected by resistor-capacitor ladder, or an inductor-capacitor ladder for charge/voltage sharing to reduce voltage ripple.