Piezoelectric Driving Circuit External Inductor Peak Current Reduction
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Solution Overview
Problem
Piezoelectric circuits face high peak currents when driven by conventional full-bridge circuits, leading to increased power consumption and switching losses.
Innovation Solution
Incorporating an external inductor connected in parallel with a sub-piezoelectric circuit, which includes a series-resonance circuit and capacitors, to manage voltage polarity changes and reduce peak currents through controlled switching of switches in a full-bridge circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a full-bridge driving circuit is used to drive the piezoelectric circuit, then the piezoelectric circuit can be driven with voltage direction changes, but high peak current is generated when charging the capacitor during switching
Solution Approach 1:
An external inductor is introduced as an intermediary element connected in parallel with the piezoelectric circuit. This inductor acts as a mediator that provides an alternative current path during voltage polarity transitions, allowing the capacitor to discharge through the inductor rather than requiring high peak current from the power source during switching transitions.
Solution Approach 2:
The external inductor is pre-charged during the steady-state operation phase before voltage polarity changes occur. When a voltage direction change is commanded, the inductor already contains stored energy and is ready to immediately supply current to support the capacitor discharge, eliminating the need for high peak current at the moment of switching.
2Speed
If switches are turned on and off frequently to change voltage direction, then the piezoelectric circuit can respond to control signals, but switching losses increase due to high peak current
Solution Approach 1:
The external inductor serves as a buffer that absorbs and releases energy during switching transitions, protecting the switches from high peak current stress. This intermediary element allows frequent switching operations to maintain fast response while the inductor handles the energy management, preventing excessive switching losses.
3Reliability
If the piezoelectric circuit includes a capacitor for energy storage, then the circuit can maintain voltage during switching, but high peak current is required to charge the capacitor whenever voltage direction changes
Solution Approach 1:
The external inductor is connected in parallel with the piezoelectric circuit to serve as an intermediary energy storage element. During voltage polarity transitions, the inductor provides a discharge path for the capacitor, allowing the capacitor to maintain voltage stability while the inductor handles the peak current demands of charging and discharging cycles.
Solution Approach 2:
The system utilizes the inductive reactance parameter of the external inductor to change the current flow characteristics. By introducing this inductive element, the circuit parameters are modified to allow energy to be transferred between the capacitor and inductor through oscillatory current, thereby reducing the peak current drawn from the power source during capacitor charging.
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
The solution effectively reduces peak currents and power consumption by ensuring switches turn on and off at zero voltage conditions, minimizing switching losses and energy input required for mechanical energy conversion.
Implementation Method 1
an external inductor connected to the sub-piezoelectric circuit in parallel, and when a polarity of a piezoelectric voltage, that is, a both-end voltage of the piezoelectric circuit is inverted, the external inductor current helps the sub-piezoelectric circuit discharged
Implementation Method 2
A piezoelectric circuit can convert electrical energy to mechanical energy and also mechanical energy to electrical energy
Data Source
AI summary
The present invention relates to a piezoelectric circuit, a piezoelectric driving circuit driving the piezoelectric circuit, and a method for driving the piezoelectric circuit. The piezoelectric circuit includes a sub-piezoelectric circuit and an external inductor coupled in parallel with the sub-piezoelectric circuit. The external inductor discharges the sub-piezoelectric circuit when a polarity of a piezoelectric voltage, that is, a both-end voltage of the piezoelectric circuit is inverted. The piezoelectric driving circuit includes first and third switches connected to a first node of the piezoelectric circuit and second and fourth switches connected to a second node of the piezoelectric circuit.