An apparatus includes a voltage regulation module that controls output voltage of a bidirectional DC to DC converter to an output voltage reference over an output current range between a positive power reference and a negative power reference. A positive power regulation module controls output power of the converter to the positive power reference over a positive constant power range between the output voltage reference and a positive output current reference. A negative power regulation module controls output power of the converter to the negative power reference over a constant power range between the output voltage reference and a maximum negative power limit, and a constant current module limits output current to a positive output current reference in a range between a minimum output voltage and output power of the converter reaching the positive power reference.