DC power supply

Power supply (6) for E/M conversion means (1), fit to convert electric energy, in the form of direct current (DC), into mechanical energy electric and fit to convert back mechanical energy into DC electrical energy. The power supply comprises a main DC supply buffer (7), fit to buffer a large amount of electric energy, control means (9) fit to enable that electric energy is transmitted from the main DC supply buffer to the E/M conversion means and to disable that electric energy is transmitted back from the E/M conversion means to the main buffer. The power supply, moreover, comprises an additional DC buffer (8), fit to supply electric energy to the E/M conversion means and to absorb electric energy transmitted back from the E/M conversion means to the additional DC buffer. A vehicle, using the power supply may comprise a DC or AC based machine having recuperation or re-generation capabilities.