An averaged modeling of the Jones DC-DC switching converter

Chopper drives are widely used in traction applications. A DC-DC power converter is connected between a fixed voltage DC source and a DC motor in order to vary the armature voltage. A feedback loop is used in order to obtain a constant speed, when the input voltage or the load torque varies. Therefore, the control-to-output transfer function of the DC motor-chopper system must be known to make possible a proper design of the feedback loop. On the other side, DC-DC power converters may use an SCR as a static switch. In that case, an auxiliary extinction circuit for the main SCR is needed. This paper shows that the extinction circuit used in the particular case of the Jones chopper modifies the transfer functions of the DC motor-chopper system, so that the feedback loop design must be carried out very carefully