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Transformerless DC To DC Converter

IP.com Disclosure Number: IPCOM000082842D
Original Publication Date: 1975-Feb-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 3 page(s) / 45K

Publishing Venue

IBM

Related People

Davis, JH: AUTHOR [+2]

Abstract

A transformerless DC-to-DC converter converts lower voltage electrical energy to higher voltage, requiring breakdown voltage of the switching devices only equal to that of the applied lower voltage.

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Transformerless DC To DC Converter

A transformerless DC-to-DC converter converts lower voltage electrical energy to higher voltage, requiring breakdown voltage of the switching devices only equal to that of the applied lower voltage.

A pair of series resonant L-C networks, L1, C1 and L3, C3 are driven by emitter-follower T3 and complimentary emitter-followers T1, T2. Common-base feedback amplifier T4 drives the parallel L-C network C2, L2 which is connected to the bases of T1 and T3. The parallel resonant network C2, L2 provides the negative base current required to turn on T3, during negative alteration of current in the series L-C networks.

To sustain oscillation, current gain of the emitter-follower drivers is large enough to exceed loses of tank L2, C2 plus the base current of T4. This is achieved when L3 equals L1, C3 equals C1, and the product of L2 times C2 is chosen to equal the product of L1 times C1.

The AC potential difference between point X1 and X3 is applied to voltage rectifier and multiplier D1, D2, D3, D4, and C4, C5, C6, and C7. The AC potentials of these points are nominally equal in amplitude and 180 degrees out- of-phase with each other, as a result of interchanging the respective positions of C1, C3 and L1, L3 as shown in Fig. 1. The DC output voltage is approximately equal to 7 (Q) VA, where Q is the series resonant voltage gain and VA is the AC signal at drive point E1. The rectifier network provides an output equal to 7 times the peak voltage at point X1, compared with a multiplication of only 4 if network L3, C3 were not utilized and if point R were returned to ground reference.

The output filter capacitor C7 is connected to E4 which is a virtual ground to the AC signal, rather than to actual ground reference. This connection causes displacement current associated with the capacitance of the diodes to remain within the feedback loop, so that oscillation can be better assured. Output voltage regulation is achieved by control...