Power converters with integrated bidirectional startup

An auxiliary circuit configured to provide various voltages and/or signals to a converter circuit controller and/or a converter circuit, the auxiliary circuit including:

• a first input terminal configured to be selectably coupled to a first voltage;
• a second input terminal configured to be selectably coupled to a second voltage;
• and
• at least one input voltage selector, wherein a selected input voltage selector of the at least one input voltage selector has a first input coupled to the first input terminal of the auxiliary circuit, a second input coupled to the second input terminal of the auxiliary circuit, and an output terminal, wherein the selected input voltage selector includes:
• a first resistive divider coupled to the first input terminal and having a first central node;
• a second resistive divider coupled to the second input terminal and having a second central node;
• a comparator having a first input, a second input, and an output configured to provide a control signal to the output terminal of the selected input voltage selector;
• a first diode coupled between the first central node and the first input of the comparator;
• a second diode coupled between the second central node and the first input of the comparator;
• and
• a reference voltage source coupled to the second input of the comparator;
• wherein the selected input voltage selector is responsive to the control signal and is configured to selectively couple, during a startup phase of the auxiliary circuit, the first voltage to the output terminal if the first voltage is greater than the second voltage, or the second voltage to the output terminal if the second voltage is greater than the first voltage, and to selectively couple, during a steady-state operational phase of the auxiliary circuit, the first voltage to the output terminal if the first voltage is less than the second voltage, or the second voltage to the output terminal if the second voltage is less than the first voltage, while the lesser voltage meets or exceeds a specified minimum voltage for the steady-state operational phase.

A power converter including:

• a bidirectional converter circuit having first and second terminals, the bidirectional converter circuit configured to have a forward mode of operation wherein a first voltage applied to the first terminal generates a second voltage at the second terminal, the bidirectional converter circuit configured to have a reverse mode of operation wherein a second voltage applied to the second terminal generates the first voltage at the first terminal, the bidirectional converter circuit being further configured to operate initially in a startup phase and thereafter in a steady-state phase;
• an auxiliary circuit configured to provide various voltages and/or signals to other circuitry;
• and
• an input voltage selector having first and second input terminals coupled respectively to the first and second terminals of the bidirectional converter circuit, the input voltage selector having an output terminal coupled to the auxiliary circuit;
• wherein the input voltage selector is configured to selectively couple the greater of the first voltage or the second voltage to the output terminal to provide power to the auxiliary circuit during the startup phase of the bidirectional converter circuit when the bidirectional converter circuit is operated in the forward mode of operation;
• and
• wherein the input voltage selector is configured to selectively couple the greater of the first voltage or the second voltage to the output terminal to provide power to the auxiliary circuit during the startup phase of the bidirectional converter circuit when the bidirectional converter circuit is operated in the reverse mode of operation.

A power converter including:

• a bidirectional converter circuit having first and second terminals, the bidirectional converter circuit configured to have a forward mode of operation wherein a first voltage applied to the first terminal generates a second voltage at the second terminal, the bidirectional converter circuit configured to have a reverse mode of operation wherein a second voltage applied to the second terminal generates the first voltage at the first terminal, the bidirectional converter circuit being further configured to operate initially in a startup phase and thereafter in a steady-state phase, the bidirectional converter circuit including a plurality of control and circuit power inputs;
• a controller coupled to the control and circuit power inputs of the bidirectional converter circuit;
• an auxiliary circuit coupled to the controller and configured to provide various voltages and/or signals to the controller, the auxiliary circuit including an input voltage selector including:
• a first input terminal coupled to the first terminal of the bidirectional converter circuit;
• a second input terminal coupled to the second terminal of the bidirectional converter circuit;
• an output terminal configured to provide power to the auxiliary circuit;
• a first input selection circuit coupled between the first input terminal and the output terminal and configured to selectively couple the first voltage to the output terminal;
• and
• a second input selection circuit coupled between the second input terminal and the output terminal and configured to selectively couple the second voltage to the output terminal;
• wherein the first input selection circuit and the second input selection circuit are configured to selectively couple the greater of the first voltage or the second voltage to the output terminal to provide power to the auxiliary circuit during the startup phase of the bidirectional converter circuit when the bidirectional converter circuit is operated in the forward mode of operation;
• and
• wherein the first input selection circuit and the second input selection circuit are configured to selectively couple the greater of the first voltage or the second voltage to the output terminal to provide power to the auxiliary circuit during the startup phase of the bidirectional converter circuit when the bidirectional converter circuit is operated in the reverse mode of operation.