An auxiliary drive circuit comprising: a first energy storage device having an output voltage, the first energy storage device being coupled to a first DC bus and configured to output electrical power to the first DC bus; a first DC-to-DC voltage converter coupled to the first DC bus and to a second DC bus, the first DC-to-DC voltage converter configured to convert the electrical power to a first voltage and to output the first voltage to the second DC bus; and a second DC-to-DC voltage converter (108, 120) coupled to the second DC bus and coupled to an auxiliary bus, the second DC-to-DC voltage converter (108, 120) configured to convert the first voltage to a second voltage, and to provide the second voltage to the auxiliary bus, the auxiliary bus configured to provide an auxiliary voltage to a plurality of auxiliary loads, wherein the second voltage is different from the first voltage, wherein the second voltage is greater than the output voltage; P characterised in that: the auxiliary drive circuit comprises: an auxiliary drive system including control devices (178, 180) and DC-to-AC inverters (164, 166) coupled to the auxiliary bus and configured to independently control the voltage input to the plurality of auxiliary loads; and a controller in operable communication with the control devices, the controller being configured to: receive an input comprising a measured value of one or more parameters associated with operation of a vehicle in which the auxiliary drive circuit is incorporated; and provide a command to command at least one of a frequency and voltage to drive at least one motor of the plurality of auxiliary loads based on the measured value of the one or more parameters at a higher operating efficiency of the plurality of auxiliary loads compared to an operating efficiency if the auxiliary drive was operated at the second voltage. a first energy storage device having an output voltage, the first energy storage device being coupled to a first DC bus and configured to output electrical power to the first DC bus; a first DC-to-DC voltage converter coupled to the first DC bus and to a second DC bus, the first DC-to-DC voltage converter configured to convert the electrical power to a first voltage and to output the first voltage to the second DC bus; and a second DC-to-DC voltage converter (108, 120) coupled to the second DC bus and coupled to an auxiliary bus, the second DC-to-DC voltage converter (108, 120) configured to convert the first voltage to a second voltage, and to provide the second voltage to the auxiliary bus, the auxiliary bus configured to provide an auxiliary voltage to a plurality of auxiliary loads, wherein the second voltage is different from the first voltage, wherein the second voltage is greater than the output voltage; P characterised in that: the auxiliary drive circuit comprises: an auxiliary drive system including control devices (178, 180) and DC-to-AC inverters (164, 166) coupled to the auxiliary bus and configured to independently control the voltage input to the plurality of auxiliary loads; and a controller in operable communication with the control devices, the controller being configured to: receive an input comprising a measured value of one or more parameters associated with operation of a vehicle in which the auxiliary drive circuit is incorporated; and provide a command to command at least one of a frequency and voltage to drive at least one motor of the plurality of auxiliary loads based on the measured value of the one or more parameters at a higher operating efficiency of the plurality of auxiliary loads compared to an operating efficiency if the auxiliary drive was operated at the second voltage. an auxiliary drive system including control devices (178, 180) and DC-to-AC inverters (164, 166) coupled to the auxiliary bus and configured to independently control the voltage input to the plurality of auxiliary loads; and a controller in operable communication with the control devices, the controller being configured to: receive an input comprising a measured value of one or more parameters associated with operation of a vehicle in which the auxiliary drive circuit is incorporated; and provide a command to command at least one of a frequency and voltage to drive at least one motor of the plurality of auxiliary loads based on the measured value of the one or more parameters at a higher operating efficiency of the plurality of auxiliary loads compared to an operating efficiency if the auxiliary drive was operated at the second voltage. receive an input comprising a measured value of one or more parameters associated with operation of a vehicle in which the auxiliary drive circuit is incorporated; and provide a command to command at least one of a frequency and voltage to drive at least one motor of the plurality of auxiliary loads based on the measured value of the one or more parameters at a higher operating efficiency of the plurality of auxiliary loads compared to an operating efficiency if the auxiliary drive was operated at the second voltage.