An Improved Cold Startup Strategy with Bias-Flip Rectifier for Piezoelectric Energy Harvesting System

To satisfy the demand of green philosophy of renewable energy, self-powered energy harvesting system from the piezoelectric energy have been applied as an alternative solution to battery. Unfortunately, piezoelectric energy harvesting system has several challenges at low excitation level, which requires additional auxiliary supply to accomplish the function of cold startup. This paper presents an improved cold startup strategy with bias-flip rectifier, which is designed in a 0.18 μm BCD process. As the simulation shows that not only the successful cold startup is attained when open voltage Voc is equal to 0.45V, but also the output voltage of PEH is 3 times of that in negative voltage rectifier (NVC). Compared with the full bridge rectifier (FBR), the bias-flip rectifier has a higher voltage conversion efficiency (VCE) of about 99%. The output power is about 14.4 μW, and has a better voltage flipping efficiency which is 93.5%.