Requirements for current and voltage measurement systems in direct current controlled industrial power inverters

In order to improve the grid-connected inverters for industry or solar fields, for example, we have done intensive research with future control methods using direct current control for such usually pulse-width modulation (PWM) controlled inverters. This paper investigates whether current measurements via sigma-delta converters are good and fast enough for the high dynamic performance of a direct current controller. In addition, the paper analyzes the capability to calculate the line-to-line voltages of the inverter from its gate signals. Today, the success of a new technology is strongly determined by its price. If sigma-delta measurements can replace expensive current measurements or the effort for a voltage measurement can be reduced, this will improve the preparedness of the industry in using improved control methods for pulse-controlled inverters. All examinations in this paper were made using the innovative switched diamond hysteresis control (SDHC) current controller with low-cost sigma-delta analog to digital (AD) converters.