Charging precision analysis of a 40 kW, 3 kV soft-switching boost converter for ultra precise capacitor charging

In this paper, the charging precision of a 40 kW, 3 kV soft-switching boost converter for capacitor charging is investigated. At the beginning, an overview on the topology and the control of the converter is given. Then, two different feedback controllers are presented and compared analytically in order to determine their sensitivity on noisy input variables. An algorithm to investigate the charging precision is illustrated. This algorithm considers the signal to noise ratio of all measured signals, the controller output limitations, quantization related errors, the finite resolution in the digital domain and the switching signal jitter in order to calculate the charging precision. All effects mentioned before are analyzed separately. This analysis shows, that the output voltage measurement signal to noise ratio is the key parameter for the charging precision. Finally, the charging precision of the presented converter is analyzed including all considered effects. The repetition accuracy of the converter is determined to be 8.3 ppm at an output voltage of 3 kW, neglecting the load connection and the input voltage variation during one switching cycle.