This paper presents a new method of low power excitation for thermal flow sensors by driving them with voltage pulses. The impulses are generated by a capacitor circuit and can have duration of some ms or less, depending on the voltage and the required resolution. Although the sensor, due to the short duration of the pulse, does not reach thermal equilibrium, the dynamic heating curve contains enough information to determine the flow rate. This pulsed excitation method provides a substantial reduction of the power consumption (by 78%, in the case of pulses of 1 ms and 5 V). Moreover additional information contained in the shape of the impulse response allows to expand the measurement range by a factor of 8 or more.
