Applying FPGA Control with ADC-Free Sampling to Multi-Output Forward Converter

In this paper, a forward converter with multiple outputs is employed to build up a circuit system with full-digital control without any analog-to-digital (ADC) converter adopted. In this circuit, all the output voltages can be regulated by individual feedback control loops. As transient load variations due to the main output happens, the secondary outputs are affected quite slightly. Furthermore, the output voltage with the largest output current adopts not only the voltage mode control but also the interleaved control and current sharing control. Therefore, if this circuit system adopts full-digital control, the number of ADCs employed is relatively large, and the corresponding cost is expensive. Accordingly, the sampling of multiple output voltages and two-phase currents without any ADCs is used herein. Moreover, a nonlinear control strategy is proposed and applied to the traditional proportional-integral-derivative (PID) controller to accelerate the load transient response. In addition, the field programmable gate array (FPGA) is used as a control kernel.

Control Strategy of Parallel Systems with Efficiency Optimisation in Switched Reluctance Generators

To solve motor heating and life shortening of parallel switched reluctance generator (SRG) induced by uneven output currents due to different external characteristics, we generally adopt current sharing control (CSC) to make each parallel generator undertake large load currents on average to improve the reliability of parallel power generation system. However, the method usually causes additional loss of power because it does not consider the efficiency characteristics of each parallel generator. Therefore, with the efficiency expression for the parallel system of SRG established and analysed, the control strategy based on differential evolution (DE) algorithm is proposed as a mechanism by which to enhance generating capacity and reliability of multi-machine power generation from the perspective of efficiency optimisation. We re-adjust the reference current of each parallel generator to transform the working point of each generator and implement the efficiency optimisation of parallel system. The performance of the proposed control method is evaluated in detail by the simulation and experiment, and comparison with traditional CSC is carried out as well.