Piezoelectric Drive Circuit Step Wave Harmonic Suppression
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing piezoelectric element drive circuits consume excessive power due to harmonics in the drive current that do not contribute to the substantial operation of the piezoelectric element, particularly the (2n+1)th order harmonic, leading to wasteful power consumption.
Innovation Solution
A piezoelectric element drive circuit is designed with a drive voltage generator that produces a step wave with a pause time of (t2−t1)/(2n+1) at the resonant frequency of (2n+1) times the predetermined frequency, suppressing the (2n+1)th order harmonic in the drive current by optimizing the impedance peaks and using an inductor in series to inhibit spike-like currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a rectangular wave drive voltage is used, then power consumption is reduced, but harmonics in the drive current cause wasteful power consumption
Solution Approach 1:
The patent applies periodic action by introducing a pause period within each drive cycle where the drive voltage is set to an intermediate potential between the positive and negative drive voltages. This periodic pause structure suppresses the (2n+1)th order harmonic components in the drive current while maintaining the fundamental driving function, thereby reducing wasteful power consumption caused by harmonics.
Solution Approach 2:
The patent changes the parameter of drive voltage waveform from a simple rectangular wave to a stepped wave with intermediate potential pauses. By modifying the voltage waveform parameters (introducing intermediate potential levels and pause durations), the patent suppresses harmful harmonic components while maintaining effective piezoelectric element operation.
2Use of energy by moving object
If the drive voltage is lowered to reduce power consumption, then energy efficiency improves, but the (2n+1)th order harmonic causes ripple in drive current
Solution Approach 1:
The periodic pause at intermediate potential is strategically timed to suppress the (2n+1)th order harmonic components that cause current ripple. By introducing these periodic interruptions in the voltage application, the patent stabilizes the drive current while maintaining energy efficiency.
Solution Approach 2:
The intermediate potential acts as an intermediary state between the positive and negative drive voltages. During the pause period, this intermediate potential level serves to dampen harmonic oscillations and stabilize the drive current, preventing ripple while maintaining overall energy efficiency.
3Productivity
If a rectangular wave drive voltage is applied, then the piezoelectric element operates, but spike-like currents are generated during voltage transitions
Solution Approach 1:
The patent introduces periodic pause periods at intermediate potential between the positive and negative voltage transitions. These periodic pauses allow the current to settle and prevent the generation of spike-like currents during voltage transitions, while maintaining continuous operation of the piezoelectric element.
Solution Approach 2:
The pause period at intermediate potential serves as a cushioning transition phase before the next voltage transition. This beforehand cushioning prevents abrupt current changes and spike generation by providing a gradual transition state between positive and negative drive voltages.
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 configuration significantly reduces wasteful power consumption by minimizing the (2n+1)th order harmonic in the drive current, enhancing the efficiency of the piezoelectric element operation by suppressing unnecessary power consumption.
Implementation Method 1
a piezoelectric element which is driven at a predetermined frequency and has a resonant frequency of (2n+1) times the predetermined frequency
Implementation Method 2
a waveform of a potential difference between the first output terminal and the second output terminal is a step wave which transitions while taking an intermediate potential
Data Source
AI summary
A piezoelectric element drive circuit includes a piezoelectric element driven at a predetermined frequency and having a resonant frequency of (2n+1) times the predetermined frequency (n is a predetermined natural number), and a drive voltage generator that has a first output terminal connected to a first terminal of the piezoelectric element and a second output terminal connected to a second terminal of the piezoelectric element. When the piezoelectric element is driven, a waveform of potential difference between the first output terminal and the second output terminal is a step wave which transitions while taking an intermediate potential. A time length for which the potential difference is the intermediate potential is around (t2−t1)/(2n+1) in a period of time from time t1 at which the potential difference falls to the intermediate potential to time t2 at which the potential difference falls to the intermediate potential subsequently.