An M phase coupled inductor includes a magnetic core including a first end magnetic element, a second end magnetic element, and M legs disposed between and connecting the first and second end magnetic elements. The electrical power supply device includes a temperature controller and a thermoelectric converter. Travel of the piston in the direction from the fluid receiving end to the fluid discharging end of the cylinder is sensed at discrete locations to provide an indication of the quantity of fluid therebetween and the related flow rate.