The present invention relates to a respiratory device for providing a supply of breathable gas to a patient breathing in successive cycles, each cycle including an inspiration phase and an expiration phase, the respiratory device comprising a blower including a motor configured to accelerate to reach an inspiration pressure provided during the inspiration phase and decelerate to reach an expiration pressure provided during the expiration phase, a first power source arranged to provide a supply of power to run the motor of the blower, and an energy storage unit configured to store energy generated by the motor when the motor decelerates, wherein when a voltage present in the energy storage unit exceeds a first threshold, the supply of power from the first power source to the motor is turned off and the motor is energized by the energy in the energy storage unit and when the voltage in the energy storage unit falls below a second threshold the supply of power from the first power source to the motor is turned on.
