The full bridge rectifier converter, Fig. 13.1 is very likely to be used to drive a dc motor as it provides four-quadrant operation. Hence the load is composed from La the armature inductance, Ra the armature resistance and Ea the back EMF induced in the armature of the dc motor. Two schemes of control for the output voltage are examined: bipolar and unipolar. The switches in each leg S1 to S4 are combinations of a transistor and a diode in anti parallel thus allowing flow of current in both directions. There is no loss of generality to consider the single switches S1 to S4 in Fig. 13.1 as bi-directional switches. Expressions for the output voltage and current are derived and time waveforms are displayed. Expressions for the distortion of the output voltage and current are also developed. A mathematical model is not used because of the simplicity of the circuit. A mathematical model is included in Appendix A 13.1. It can be used to extend the analysis in investigating the input current. This is useful in deciding the size and rating of the filter capacitors that usually accompany the output stage of a dc supply.