Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

In this paper a class E based methodology for driving a piezoelectric ceramic transducer (PZT) is described.

Page 9, Figure 8. Reference of the current signal is different of the reference of the inverting input of the comparator. In general it is not clear how this zero crossing detector operates, as there is no information for the current sensor.

Page 11, Figure 11. A smaller time-step (higher waveforms time detail) would show more clear the transients. 

The operation of the PLL could have some explanation. A general flow chart of the algorithm can be added.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The proposed model is a class E ZVS resonant inverter with a CLC filter and digital frequency tracking for driving a piezoelectric transducer in ultrasonic cleaning. A digital signal processor (DSP) adjusts the operating frequency in real time based on load changes using a phase-locked loop (PLL) control method.

The authors further posit that the proposed method ensures that the inverter maintains zero-voltage switching (ZVS) operation across a frequency range of 30.0 kHz to 34.0 kHz, thereby improving energy efficiency and reducing switching losses.
In order to enhance the depth of scientific research, it could be better  to provide commentary on the following points:
- The impact of parasitic elements within the converter circuit remains to be elucidated. Specifically, there has been a paucity of discourse concerning the   influence of the transistor on-state resistance (Rds(on)), the series equivalent resistances of the filter (C2L2C3), and their effect on the mentioned ZVS range.

- No mathematical analysis of power losses in the circuit has been performed. It would be beneficial to compare the calculated and experimentally obtained results.

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

1. The inductor L1 in the proposed system appears to be relatively large and heavy. The authors are encouraged to clarify whether its physical size can be reduced, and to discuss potential design trade-offs involved in such reduction.
2. In lines 107–108, the CLC filter is described as consisting of a series inductor L2, a shunt capacitor C2, and another series capacitor C3. Is this description correct? It does not seem to match the circuit shown in Figure 2.
3. In lines 167–168, Figure 4(d) is stated to combine series capacitors C2 and Cx into a single effective capacitance Ct. However, this designation does not match the Cy label shown in Figures 4(c) and 4(d). Please clarify and ensure consistent notation throughout the manuscript.
4. The reverse recovery characteristics of switch Q1 are of concern. The authors should provide data or discussion on whether the reverse recovery current is excessively high and whether the recovery time is unduly long, along with its potential impact on system performance.
5. When comparing the experimental waveforms of iQ1 and iC1 with their simulated counterparts, the measured iQ1 waveform exhibits pronounced current oscillations. This discrepancy may indicate inaccuracies in the simulated component parameters. The authors are encouraged to elaborate on the possible causes of this deviation.
6. Is the proposed system adaptable to different load conditions?
7. It is recommended that the authors provide the dynamic response of the system when subjected to load changes, such as transitions between heavy-load and light-load conditions, to validate its robustness.

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Although the operation of the circuit in Fig. 9 is apparent, the different symbols in non-inverting input reference (ground) and the inverting input reference (ground) and negative comparator supply voltage will confuse the reader. Same ground symbols exist in Fig. 10 also, but because of the galvanic isolation of the optocoupler different grounds can exist in this case.

The different ground symbols are the problem in Fig. 9 as the comparator does not operate correctly with different grounds.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf