Piezoelectric Transformers: An Historical Review

Abstract

Piezoelectric transformers (PTs) are solid-state devices that transform electrical energy into electrical energy by means of a mechanical vibration. These devices are manufactured using piezoelectric materials that are driven at resonance. With appropriate design and circuitry, it is possible to step up and step down the voltages between the input and output sections of the piezoelectric transformer, without making use of magnetic materials and obtaining excellent conversion efficiencies. The initial concept of a piezoelectric ceramic transformer was proposed by Charles A. Rosen in 1954. Since then, the evolution of piezoelectric transformers through history has been linked to the relevant work of some excellent researchers as well as to the evolution in materials, manufacturing processes, and driving circuit techniques. This paper summarizes the historical evolution of the technology.Keywords: piezoelectric transformer; piezoelectric-based power supply; non-magnetic transformers Historical Introduction 1920s-1930s: Early Studies on Piezoelectric Transformers Using Salt Rochelle Single CrystalThe first studies on electrical to electrical conversion using piezoelectric materials took place in the late 1920s and early 1930s. Alexander McLean Nicolson has the honor of being the first researcher to investigate the idea of a piezoelectric transformer. Nicolson considered two single crystal blocks preloaded against each other with an external frame (Figure 1). Abstract: Piezoelectric transformers (PTs) are solid-state devices that transform electrical energy into electrical energy by means of a mechanical vibration. These devices are manufactured using piezoelectric materials that are driven at resonance. With appropriate design and circuitry, it is possible to step up and step down the voltages between the input and output sections of the piezoelectric transformer, without making use of magnetic materials and obtaining excellent conversion efficiencies. The initial concept of a piezoelectric ceramic transformer was proposed by Charles A. Rosen in 1954. Since then, the evolution of piezoelectric transformers through history has been linked to the relevant work of some excellent researchers as well as to the evolution in materials, manufacturing processes, and driving circuit techniques. This paper summarizes the historical evolution of the technology.

Ceramic-Heterostructure-Based Magnetoelectric Voltage Transformer with an Adjustable Transformation Ratio

“…where φ is the phase shift between voltage and current. The active power in the output circuit was calculated as P 2 = U 2 2 /2R L . The impedance of the transformer was measured using a panoramic RLC-meter (AM-326).…”

“…Voltage transformers, which are used for converting the amplitude of an alternating voltage and the galvanic isolation of elements of electronic circuits with respect to the dc voltage, are among the most important elements of modern electronics. Currently, compact transformers using the phenomenon of electromagnetic induction [1] and solid-state transformers employing the piezoelectric effect [2] are widely used in low-power electronic circuits. However, both types of transformers have several disadvantages.…”

Effects of Disc-Shaped Piezoelectric Size Reduction on Resonant Inductorless DC-DC Converter

“…R represents the mechanical damping (and its associated losses) but thermal effects and semiconductor losses are neglected. The expression of the efficiency η and maximal output power Pout_max are given in (2) and 3, where ω is the radial resonant pulsation and RL is the resistive load.…”

“…Piezoelectric-based converters have proved to be a very good alternative for high-gain, low-power converters [1]. For low-power range (until some dozen of Watts) piezoelectric elements have inherent advantages compared to magnetic such as a very high quality factor leading to very high efficiency, a planar shape, a high-power density, low EMI radiations [2] and should be suitable for integration in silicon . The converter described in Figure1 and first presented in [3], [4], has the particularity of using the piezoelectric material as an energy storage element, contrary to most common converters with piezoelectric transformers.…”

Evaluating the Reduction of Stress Intensity Factor in Center-Cracked Plates Using Piezoelectric Actuators

“…Thus, different necessary step-up conversion to drive the piezoelectric actuator had been proposed in the literature. Vazquez Carazo and Uchino [16] and Vazquez Carazo [17] proposed a novel DC-AC converter using a piezoelectric transformer, capable of converting a 24 V DC input voltage up to 600 V AC output voltage with frequency and magnitude control for driving piezoelectric actuators. Other circuit topologies with higher step-up ratios and better control strategies to drive piezoelectric actuators were also presented [18], but these topologies often mean larger volume and more complex control methods.…”