A low power consumption driver with low acoustics for piezoelectric synthetic jets
The low profile piezoelectric synthetic jet is a promising approach for forced air convection cooling of electronics for high density and portable applications. The synthetic jet considered in this paper, known as a DCJ ([2]), consists of a pair of piezoelectric discs mounted on a frame and driven with a voltage, which causes the discs to mimic the action of a pair of bellows. This DCJ requires a sinusoidal waveform of 125-175 Hz at an amplitude up to bQV, and must operate from a 5V DC source. The mostly capacitive load of the DCJ presents a challenge for typical amplifiers. Furthermore, many applications require quiet operation; hence the jet driving waveform must have very low distortion to prevent audible acoustic noise. This paper describes a bidirectional power driver topology for driving capacitive loads based on a dual flyback topology, along with a low-cost, pure sine reference generator with predistortion to allow a clean output waveform without feedback. The driver achieves low power consumption (rì 250mW) with low harmonic content. The use of predistortion and a delta-sigma DAC compensates for the inherent flyback converter nonlinearity and the low resolution DAC typical of low-cost microcontrollers. The paper describes and presents experimental results for a design that accomplishes these objectives in a 30 mm × 30 mm × 4 mm volume.