A system including series hybrid architecture using compounded doubly fed induction machines, the system comprising: a controller configured to control the operation of the system; a power source configured to convert a first form of energy to a second form of energy; a first machine configured to generate power, wherein the first machine is mechanically coupled to the power source; a second machine configured to control equipment, wherein the first machine is electrically coupled to the second machine; a first power electronics circuit configured to modify electrical power of the first machine, characterised in that modifying the electrical power of the first machine comprises: detecting, at the first power electronics circuit, the electrical power; comparing the electrical power to a value for an electrical output level; providing an excitation signal to the first machine based on the comparison; modifying the electrical power based on the excitation signal; transmitting the modified electrical power to a second machine to operate the second machine; and a second power electronics circuit configured to detect an input to the second machine and provide a second signal to control an output of the second machine, wherein providing the second signal comprises: receiving the modified electrical power at the second power electronics circuit; comparing the received modified electrical power to a value for a threshold level; selecting a speed of operation for the second machine by controlling the operation of the second machine; comparing a current speed of operation of the second machine to the selected speed of operation; and providing an excitation signal to the second machine based at least in part on the comparison to control the speed of operation of the second machine. a controller configured to control the operation of the system; a power source configured to convert a first form of energy to a second form of energy; a first machine configured to generate power, wherein the first machine is mechanically coupled to the power source; a second machine configured to control equipment, wherein the first machine is electrically coupled to the second machine; a first power electronics circuit configured to modify electrical power of the first machine, characterised in that modifying the electrical power of the first machine comprises: detecting, at the first power electronics circuit, the electrical power; comparing the electrical power to a value for an electrical output level; providing an excitation signal to the first machine based on the comparison; modifying the electrical power based on the excitation signal; transmitting the modified electrical power to a second machine to operate the second machine; and a second power electronics circuit configured to detect an input to the second machine and provide a second signal to control an output of the second machine, wherein providing the second signal comprises: receiving the modified electrical power at the second power electronics circuit; comparing the received modified electrical power to a value for a threshold level; selecting a speed of operation for the second machine by controlling the operation of the second machine; comparing a current speed of operation of the second machine to the selected speed of operation; and providing an excitation signal to the second machine based at least in part on the comparison to control the speed of operation of the second machine. detecting, at the first power electronics circuit, the electrical power; comparing the electrical power to a value for an electrical output level; providing an excitation signal to the first machine based on the comparison; modifying the electrical power based on the excitation signal; transmitting the modified electrical power to a second machine to operate the second machine; and a second power electronics circuit configured to detect an input to the second machine and provide a second signal to control an output of the second machine, wherein providing the second signal comprises: receiving the modified electrical power at the second power electronics circuit; comparing the received modified electrical power to a value for a threshold level; selecting a speed of operation for the second machine by controlling the operation of the second machine; comparing a current speed of operation of the second machine to the selected speed of operation; and providing an excitation signal to the second machine based at least in part on the comparison to control the speed of operation of the second machine. receiving the modified electrical power at the second power electronics circuit; comparing the received modified electrical power to a value for a threshold level; selecting a speed of operation for the second machine by controlling the operation of the second machine; comparing a current speed of operation of the second machine to the selected speed of operation; and providing an excitation signal to the second machine based at least in part on the comparison to control the speed of operation of the second machine.