A CMOS MPPT power conditioning circuit for energy harvesters

Abstract

This paper presents the design of an ultra-low power consumption power conditioning circuit with an analogue maximum power point tracker to maximize the scavenged power generated by energy harvesting devices. Excess power is stored in a large storage capacitor to be used once the power generated by the harvester falls below the power required by the load. The circuit was designed to work with various types of energy harvesters such as solar cells and piezoelectric devices, thus making it compatible with both AC and DC input voltages. The AC/DC-to-DC converter topology employed, does not make use of any rectifier, in order to maximize the power efficiency of the converter. This power conditioner was designed using the AMS High Voltage 0.35 µm CMOS technology. The power conditioner cold starts with a minimum input voltage of 1 V and can subsequently operate with a wide voltage range of 0.2 V to 50 V to be compatible with various types of harvesters. It consumes 250 nW and can work with harvesters capable of generating power in the microwatt and milliwatt range.