| 摘要 |
A switched-capacitor circuit has two capacitors and two MOSFETs that cross-couple the capacitors, connecting the anode of one to the cathode of the other, and vice-versa. When either MOSFET is on, the capacitors are in series; the order alternates as the MOSFETs alternate. A reversing cyclical voltage suitable as a primary drive for a transformer is generated. If the MOSFETs alternate with no dead-time, a square-wave excitation is generated. With off-time, a pwm excitation is generate. Charge is maintained on the switched-capacitors using a symmetrical common-mode inductor. A bifilar winding is center-tap as its input, and the ends of the bifilar winding are connected to the capacitors. The capacitors are effectively in parallel. Because the charging current flows and returns through each leg of the inductor equally, it cannot magnetize the inductor core or cause any flux change. Because any voltages induced in the windings are common-mode, flux change in the core does not affect the charging current. The ac voltage generated when the capacitors switch is across the full inductor. Not only does the inductance attenuate any noise, the center-tap is between equal and opposite negative and positive voltages, which cancel. There is very little noise at the input. The circuit is reciprocal, so it can be used to rectify a transformer output. Two can be used as a bi-directional transformer isolated power converter. Several modules using 1 to 1 transformers can be stacked for a power converter having a higher ratio of input to output voltage. |
| 主权项 |
1. A symmetrical power converter comprising
a common-mode-inductor and a cross-coupled capacitor switching circuit, the common-mode inductor comprising at least a first inductor core, and a bifilar winding wound through the at least a first inductor core, the bifilar winding having a start of the bifilar winding connected to a first common-mode capacitor, with a first wire of the bifilar winding connected to the anode of the first common-mode capacitor, and with a second wire of the bifilar winding connected to the cathode of the first common-mode capacitor, an end of the bifilar winding connected to a second common-mode capacitor, with the first wire of the bifilar winding connected to the anode of the second common-mode capacitor, and with the second wire of the bifilar winding connected to the cathode of the second common-mode capacitor, the bifilar winding further having a center-tap as its input for the common-mode inductor, with the first wire of the bifilar winding connecting to an input voltage, and with the second wire of the bifilar winding for connecting to the return of the input voltage, the cross-coupled capacitor switching circuit comprising a first switch connecting the anode of the first common-mode capacitor to the cathode of the second common-mode capacitor, and a second switch connecting the anode of the second common-mode to the cathode of the first common-mode capacitor, whereby the first switch and the second switch may be closed alternately to generate a first alternating voltage between the anode of the first common-mode capacitor and the anode of the second common-mode capacitor, and to generate a second alternating voltage between the cathode of the first common-mode capacitor and the cathode of the second common-mode capacitor, the first alternating voltage and the second alternating voltage being equal in magnitude and timing. |
