Piezoelectric Transformer Frequency Control via Input Phase Detection

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Solution Overview

Problem

Existing methods for frequency control of piezoelectric transformers, particularly in plasma generators, face challenges in achieving maximum efficiency without affecting the transformer's operation significantly, as they often require tapping output signals or additional electrodes, which complicate the structure and negatively impact performance.

Innovation Solution

A method and circuit arrangement that regulate the frequency of a piezoelectric transformer by detecting phase information of the input impedance and adjusting the AC voltage based on predetermined phase criteria, allowing optimal operation without affecting the transformer's behavior on the output side, using only input-side information.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Extent of automation

If voltage is tapped from the output side for frequency control, then frequency regulation is achieved, but the amplitude of output voltage is affected and the oscillation behavior of the piezo element is disturbed

Engineering Contradiction:

Improvefrequency controlVSAvoidoutput voltage stability

Core Design Contradiction:

Extent of automationVSReliability

Solution Approach 1:

The patent extracts the frequency control function from the output side to the input side by detecting the phase of the input voltage. This separation allows frequency regulation without tapping into the output voltage, thereby maintaining output stability while achieving automated frequency control through input-side phase detection.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces phase detection of the input voltage as an intermediary mechanism for frequency control. Instead of directly controlling frequency through output voltage tapping, the phase information of the input voltage serves as a mediator that enables indirect frequency regulation without disturbing the output oscillation behavior.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If additional electrodes are added for feedback signal, then frequency control capability is improved, but the structure of the piezoelectric component is complicated

Engineering Contradiction:

Improvefrequency control capabilityVSAvoidstructure complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent enables the piezoelectric transformer to self-regulate its operating frequency by detecting the phase of its own input voltage. This self-service approach eliminates the need for additional feedback electrodes or external frequency control circuits, maintaining structural simplicity while achieving adaptive frequency control.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The input voltage serves multiple functions: it provides the driving signal for the piezoelectric element and simultaneously serves as the source for frequency control information through phase detection. This multi-functionality eliminates the need for separate control electrodes or circuits, reducing structural complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Extent of automation

If output voltage is used for frequency control, then frequency regulation is possible, but the mode of operation of the piezoelectric transformer is negatively affected

Engineering Contradiction:

Improvefrequency regulationVSAvoidoperation efficiency

Core Design Contradiction:

Extent of automationVSProductivity

Solution Approach 1:

Instead of using output voltage for frequency control (conventional approach), the patent inverts the control direction by using input voltage phase detection. This inversion allows frequency regulation to be achieved without the negative effects associated with output-side control, maintaining optimal operating mode and efficiency.

Inventive Principle:

Principle #13The other way round (Inversion)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enables the piezoelectric transformer to operate at maximum efficiency under various conditions without compromising its functionality, reducing heating and allowing higher plasma outputs while maintaining a simple structure and minimizing the need for output-side signal tapping.

Implementation Method 1

when a sinusoidal AC voltage is applied to the input side, this is deformed, e.g. This in turn generates a corresponding output voltage on the output side due to the direct piezoelectric effect

Methodology Applied

Scientific EffectDirect piezoelectric effect: Piezoelectric Effect

Implementation Method 2

If the frequency of the applied input voltage matches the resonant frequency of the piezoelectric element, electromechanical resonance of the element results, so that the mechanical vibration reaches a maximum

Methodology Applied

Scientific EffectElectromechanical resonance: Resonance

Data Source

PatentEP3329522B1Method for frequency control of a piezoelectric transformer and switch arrangement comprising a piezoelectric transformer

Publication Date: 2021.06.30 TDK ELECTRONICS AG

Figure 1~2
Figure 3A~4

AI summary

The invention relates to a method for frequency control of a piezoelectric transformer (1), wherein a piezoelectric transformer (1) is excited on an input side (1a) with an alternating voltage of predetermined frequency, and phase information of the input impedance of the piezoelectric transformer (1) is detected in a return path. The detected phase information regarding a predetermined phase criterion is subsequently evaluated and the frequency of the alternating voltage is controlled according to the evaluated phase information. In addition, a switch arrangement is described for carrying out a corresponding frequency control.