Application of a Digital Trigger Generator to NSLS Booster and Storage Ring Dipole Power Supplies

The digital trigger generator described in reference (1) has been used to control a number of power supplies at the NSLS. Two extensions to the basic controller have been used to preserve its inherent high performance in particular applications. In the case of fast slew rate applications, the bandwidth limits of the supply generate errors in tracking the current reference. The repetitive nature of the NSLS Booster cycle has made possible an adaptive feed-forward scheme which corrects the errors of a given cycle based on data derived from previous cycles. For slowly varying current regulated supplies, the residual subharmonic ripple due to unbalanced phase voltages, transformer unbalance, etc. is corrected by means of a microprocessor based harmonic analyser which feeds data to the phase correction input of the controller.