Transformer-based isolated bi-directional DC-DC power converter, and method and controller for using same
View Patent ↗A transformer based isolated bi-directional DC-DC power converter may have signals for controlling power transfer in first and second directions are derived from the same side of the transformer. The converter may include a transformer, a first switching circuit, a second switching circuit, and a controller. In a first mode, the controller controls the first and second switching circuits, and power is transferred from a first side to a second side. In a second mode, the controller controls the first and second switching circuits, and power is transferred from the second side to the first side.
1. A bi-directional DC-DC power converter comprising:
an isolation barrier configured to provide electrical isolation between a first side of the bidirectional DC-DC power converter and a second side of the bi-directional DC-DC power converter;
a first switching circuit located on a first side of the isolation barrier;
a second switching circuit located on a second side of the isolation barrier;
a controller, electrically coupled to the second side of the isolation barrier and electrically isolated from the first side of the isolation barrier, for controlling one or more of the first and second switching circuits, wherein, in a first mode in which power is transferred from the first side of the bidirectional DC-DC power converter to the second side of the bidirectional DC-DC power converter, the controller controls one or both of the first and second switching circuits based at least partially on an output of the second switching circuit, and wherein, in a second mode in which power is transferred from the second side of the bidirectional DC-DC power converter to the first side of the bidirectional DC-DC power converter, the controller controls one or both of the first and second switching circuits based at least partially on an input voltage of the second side of the bidirectional DC-DC power converter;
a selector switch, wherein a transformer of the bidirectional DC-DC power converter operates in one of the first mode and the second mode based on a state of the selector switch; and
an analog-to-digital converter (ADC), electrically coupled to the second side of the isolation barrier and electrically isolated from the first side of the isolation barrier, operable to generate a digital representation of the output of the second switching circuit in the first mode and a digital representation of the input voltage of the second side of the bidirectional DC-DC power converter in the second mode;
wherein the transformer of the bidirectional DC-DC power converter includes a first winding on the first side of the isolation barrier and a second winding on the second side of the isolation barrier, the first switching circuit configured to couple to the first winding, and the second switching circuit configured to coupe to the second winding; and
wherein,
in the first mode, the output of the second switching circuit is coupled to an input of the analog-to-digital converter via a first state of the selector switch, and
in the second mode, an input of the second winding of the transformer of the bidirectional DC-DC power converter is coupled to the input of the analog-to-digital converter via a second state of the selector switch.
2. The bi-directional DC-DC power converter as claimed in claim 1 , wherein the transformer of the bidirectional DC-DC power converter operates as a forward power converter in the first mode and a backwards power converter in the second mode.
3. The bi-directional DC-DC power converter as claimed in claim 2 , wherein (i) in the first mode, the bi-directional DC-DC power converter operates as a voltage-fed converter and (ii) in the second mode, the bi-directional DC-DC power converter operates as a current-fed converter.
4. The bi-directional DC-DC power converter as claimed in claim 1 , in which the controller is responsive to a voltage at the input of the second winding of the transformer of the bidirectional DC-DC power converter to estimate a voltage at an input/output node of the first switching circuit.
5. The bi-directional DC-DC power converter as claimed in claim 1 , further comprising:
a sampling circuit, wherein the sampling circuit (i) is operable in the second mode and (ii) samples a voltage at the input of the second winding.
6. The bi-directional DC-DC power converter as claimed in claim 1 , wherein a phase between switching of switches in the first switching circuit and switching of switches in the second switching circuit is adjustable so as to control a power transfer in a first direction and a second direction of the bi-directional DC-DC power converter.
7. The bi-directional DC-DC power converter of claim 1 , wherein the isolation barrier includes a second transformer.