Precise Volt-Second Measuring Instrument for Voltage-Source Inverters

Accurately measuring pulse modulated voltage is challenging due to its steep voltage slopes and time delays during switching. However, for modern sensorless drives, knowledge of instantaneous phase voltage is required for e.g. flux linkage estimation. This paper presents a novel measuring technique for precise volt-second sensing that combines the advantages of analog circuit technology with the performance of an FPGA. The presented sensor prototype for volt-second sensing is based on the concept of an analog synchronous voltage-to-frequency converter. It is shown how to save additional expensive components by utilizing existing control hardware. The working principle is demonstrated by simulations and finally validated by measurements on the testbench.