US 12,261,539 B2
Self-oscillating resonant push-pull converter with a synchronous rectifier for phase-modulated bidirectional communication
Max Bauer, Rheinfelden (DE); Peter Wehrli, Aarau (CH); and Lukas Gätzi, Zürich (CH)
Assigned to Endress+Hauser SE+Co. KG, Maulburg (DE)
Appl. No. 18/004,729
Filed by Endress+Hauser SE+Co. KG, Maulburg (DE)
PCT Filed Jun. 21, 2021, PCT No. PCT/EP2021/066735
§ 371(c)(1), (2) Date Jan. 9, 2023,
PCT Pub. No. WO2022/008211, PCT Pub. Date Jan. 13, 2022.
Claims priority of application No. 10 2020 118 176.0 (DE), filed on Jul. 9, 2020.
Prior Publication US 2023/0253890 A1, Aug. 10, 2023
Int. Cl. H02M 3/335 (2006.01); H02M 3/00 (2006.01)
CPC H02M 3/33592 (2013.01) [H02M 3/01 (2021.05); H02M 3/33584 (2013.01)] 15 Claims
OG exemplary drawing
 
1. A method for operating a communication system for bidirectional galvanically isolated communication, the method comprising:
providing the communication system, including:
a DC/DC converter circuit, including:
a push-pull driver to which a reference clock with a fixed frequency can be applied on an input side;
a transformer having a primary coil and a secondary coil, wherein the push-pull driver is connected, on an output side, to the primary coil;
a synchronous rectifier connected, on an AC side, to the secondary coil;
a resonant circuit including a capacitance and one inductance, the resonant circuit being designed such that a part of the resonant circuit is on a primary side of the transformer and another part of the resonant circuit is on a secondary side of the transformer;
a decoupling inductance connected on a secondary side of the transformer and downstream of the synchronous rectifier and which is not part of the resonant circuit; and
an output capacitance connected in series with the decoupling inductance and via which an output voltage is provided;
a transmitting transfer channel having a first modulator unit connected for data transfer to a first demodulator unit via a second galvanic isolation; and
a receiving transfer channel having a second demodulator unit connected to a second modulator unit via a third galvanic isolation,
wherein, for the modulation units and demodulation units, the DC/DC converter circuit also provides, on the primary side and the secondary side, the reference clock required for modulation and demodulation;
applying to the push-pull driver on the input side the reference clock having the fixed frequency that is not changed during operation.