Piezoelectric energy harvesters generate electrical power from ambient mechanical vibrations, making these vibrations a viable energy source for powering wireless sensor and identifier nodes. In order to harvest an appreciable amount of power, piezoelectric devices are typically inserted into high-Q mechanical resonant structures that significantly limit their harvesting bandwidth. The dynamic active energy harvesting method has been proposed as a way to widen the bandwidth of resonant piezoelectric energy harvesters; however, an autonomous design has not yet been demonstrated. This paper demonstrates the first autonomous implementation of this method. This was accomplished through the use of a resonant inverter topology in combination with a low-power analog control circuit design that reduces the computational demand of the microcontroller. Experimental results using the Mide Volture V20w piezoelectric device show that the harvested power is up to twice that of the adaptive rectifier method. These results include previously ignored loss mechanisms such as control losses, gating losses, and phase detection losses, making this system the first autonomous energy harvesting system of its kind.