This study proposes a sensorless speed-control system for a DC-link capacitorless inverter-based interior permanent magnet synchronous motor (IPMSM) drive system via measuring switching-state current-ripples. By measuring the current-ripple of each pulse-width modulation switching-state, the rotor position of the IPMSM can be estimated. As a result, the hardware of a high-frequency sinusoidal voltage or current source is not required. In addition, by suitably selecting the different levels of the fictitious DC-link voltage and compensating the duty cycle of the switching interval, the estimated rotor position error can be effectively reduced to nearly 50%. A 32-bit digital signal processor, TMS-320LF-2407A, is used to execute the rotor position estimation algorithm and the speed-controller. Experimental results validate the theoretical analysis. The proposed sensorless IPMSM drive can be operated from 3 to 2000 r/min. This study proposes a method to implement a DC-link capacitorless inverter IPMSM drive system and improve its performance without injecting any high-frequency voltage or current.