Sensorless SPMSM Control for Heavy Handling Machines Electrification: An Innovative Proposal

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The article highlights that sectors such as construction machinery are only beginning their transition toward electrification. A broader comparative study of similar products is recommended, including data analysis on technological trends and application developments, which is currently lacking in this work.

The manuscript does not provide a systematic comparison between the proposed fan drive system and conventional alternatives (e.g., mechanical or hydraulic drives). It is recommended that the authors include data comparing different approaches in terms of efficiency, cost, and reliability to better demonstrate the advantages of the proposed solution.

Key technical aspects—such as motor control strategies, power electronics configurations, and thermal management mechanisms—are not sufficiently discussed in terms of their strengths, limitations, and implementation details across different product designs. The authors are encouraged to elaborate on the control methods, thermal protection strategies, and algorithmic principles to enhance the technical clarity and depth of the work. Additionally, further discussion should be included to strengthen the strategic vision and long-term applicability of the research.

While the paper presents a technical solution aimed at addressing long-term challenges, the authors should provide more explicit justification for why the data and findings can be generalized across products. If generalization is not feasible, such limitations should be clearly acknowledged in a dedicated section.

Regarding the experimental setup, ethical considerations mainly involve the timeliness of testing and the knowledge background of the participants. The authors should clarify the expertise and roles of individuals involved in the experiments.

Lastly, although the methodology and results sections are reasonably robust, the paper would benefit from more critical engagement with international literature to better establish its global scientific significance. The authors should also indicate in the conclusion whether the observed differences in experimental results are statistically significant.

Author Response

Comments 1: [The article highlights that sectors such as construction machinery are only beginning their transition toward electrification. A broader comparative study of similar products is recommended, including data analysis on technological trends and application developments, which is currently lacking in this work.] 

Response 1: [Many thanks for this suggestion. We provided in the introduction an overview of the technological trends and application developments that enriches the paper.] 

 

Comments 2: [The manuscript does not provide a systematic comparison between the proposed fan drive system and conventional alternatives (e.g., mechanical or hydraulic drives). It is recommended that the authors include data comparing different approaches in terms of efficiency, cost, and reliability to better demonstrate the advantages of the proposed solution.] 

Response 2: [Thank you for this request. We added in the introduction a comparison of the main features of hydraulic and electric machines with special focus on power density, reliability, and efficiency.] 

 

Comments 3: [Key technical aspects—such as motor control strategies, power electronics configurations, and thermal management mechanisms—are not sufficiently discussed in terms of their strengths, limitations, and implementation details across different product designs. The authors are encouraged to elaborate on the control methods, thermal protection strategies, and algorithmic principles to enhance the technical clarity and depth of the work. Additionally, further discussion should be included to strengthen the strategic vision and long-term applicability of the research.] 

Response 3: [Many thanks for this suggestion, we added a discussion regarding thermal management and strategies at the end of the introduction. A discussion regarding sensorless strategies as been also added with a brief comparison between MRAS, MSO, EKF at the begin of the section “2.2. Sensorless MRAS algorithm”.] 

 

Comments 4: [While the paper presents a technical solution aimed at addressing long-term challenges, the authors should provide more explicit justification for why the data and findings can be generalized across products. If generalization is not feasible, such limitations should be clearly acknowledged in a dedicated section.] 

Response 4: [Thanks for your suggestion, a discussion regarding long-term challenges for heavy handling machines has been added at the end of the introduction.] 

 

 

 

 

Comments 5: [Regarding the experimental setup, ethical considerations mainly involve the timeliness of testing and the knowledge background of the participants. The authors should clarify the expertise and roles of individuals involved in the experiments.] 

Response 5: [Thanks for your suggestion. A section entitled “Author Contributions” has been added, at the end of the paper, to clarify the role and the contribution of every researcher involved in this work.] 

 

Comments 6: [Lastly, although the methodology and results sections are reasonably robust, the paper would benefit from more critical engagement with international literature to better establish its global scientific significance.] 

Response 6: [Thanks for your suggestion, the literature review has been enriched with a few references regarding sensorless algorithms, PI regulator tuning and evaluation of the computational requirements, together with a critical review of these topics.] 

 

Comments 7: [The authors should also indicate in the conclusion whether the observed differences in experimental results are statistically significant.] 

Response 7: [Thanks for the thorough review, in particular, regarding efficiency plots observed differences in experimental results have been discussed and the statistical significance has been also examined adding three new figures (fig. 11, fig. 12, fig. 13).] 

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript addresses a current and relevant topic: the electrification of secondary actuators (in particular, cooling fans) in heavy-duty handling machines, with a particular focus on the compactness of the system and the use of sensorless control techniques. However, the treatment suffers from several structural shortcomings, clarity of exposition and scientific completeness, which significantly compromise its potential impact.

The manuscript alternates descriptive, modeling and implementation parts in a disorderly way. A restructuring in more sections and subsections is recommended to improve the reading, for example according to the following scheme:

1. Introduction: State of the art on the electrification of work machines. Motivations for fan electrification.

2. Hardware architecture: Motor, integrated inverter, thermal requirements, interfaces (CAN, 48V).

3. Modeling and control: FOC modeling. PI control. Sensorless MRAS: principles, scheme and formulation.

4. FW/SW implementation: State machine, transition conditions, safety management.

5. Experimental validation: Bench tests, efficiency graphs.

6. Discussion and conclusions

The manuscript does not include any direct comparison with similar techniques present in the literature, a fundamental element to evaluate its innovative contribution. It is essential to integrate a comparison with other works in the literature highlighting pros and cons. The most effective way is to show a comparison table between methods choosing appropriate criteria and methods for such a comparison analysis.

For example, in the literature there are many articles on sensorless control of large-scale synchronous motors that exploit feedback linearization to improve performance compared to FOC since they integrate the nonlinear dynamics through the differential model, and that use state observers such as Utikin or EKF.

It is suggested to analyze the results of other articles and discuss relative advantages/disadvantages compared to the sensorless MRAS algorithm presented in the manuscript.

The choice of FOC control parameters is never discussed in the manuscript. Were simulations and recursive algorithms used to scale these parameters? Were heuristic logics used?
A discussion of this aspect is required.

The work describes FW implementations, but does not offer any evaluation of the computational complexity of the implemented control. An estimate of the complexity in terms of operations per cycle (MIPS) or CPU usage is required, also highlighting the HW target for the SW implementation.

For this type of analysis, it is strongly recommended to take inspiration from the following works in the literature:

Dini, P., & Saponara, S. (2022). Processor-in-the-loop validation of a gradient descent-based model predictive control for assisted driving and obstacle avoidance applications. IEEE Access, 10, 67958–67975.

Dini, P., et al. (2023). Real‐time electro‐thermal modelling and predictive control design of resonant power converter in full electric vehicle applications. IET Power Electronics, 16(12), 2045–2064.

The authors declare that the system has been tested experimentally on a load bench. It is requested to show a figure of the load bench in which the wiring to the measuring instruments and the connection torque meter-coupling to the rotation axis are evident (with possible vibration absorption systems for misalignment or eccentricity).

The manuscript does not explicitly report the characteristics of the motor under examination such as the characteristic speed-torque curve, nor the parameters of the park model necessary for the control design.

As experimental results the authors report only 2 graphs.

A much more detailed analysis of the experimental results is necessary! How many and which load torque protocols have been validated? Are only piecewise constant torques applied? How much power is absorbed by the machine?
It is certainly necessary to compare at least the sensorless vs sensored behavior, on classic evaluation metrics (e.g. initial overshoot, alignment time...) for how much performance loss there is. Better would be a comparison of two sensorless techniques on the same machine.

The presented contribution is potentially interesting, but not yet ready for publication in its current form. A major revision is recommended, with structural reorganization, integration of comparative references, computational analysis and improvement of experimental validation.

Comments on the Quality of English Language

Section 0 – Introduction

Replace “to increase overall system efficiency and flexibility and enable the use of advanced control algorithms” with “to increase overall system efficiency and flexibility and enable the use of advanced control algorithms”.

“High reliability standards” is not idiomatic; use “reliability standards” instead.

Avoid repetition and consider rewriting the opening paragraph to “Electric earthmoving equipment is becoming increasingly popular…” for clarity.

Section 1.1 – Mathematical Approach

“To ensure high efficiency” → use “to ensure high efficiency”.

“To simplify the control architecture” → should read “to simplify the implementation of the control architecture”.

“The homopolar components in the Clarke matrix can be neglected” → correct to “the homopolar component in the Clarke matrix can be neglected”.

Remove redundant punctuation in "under the isotropic motor assumption, (Ld = Lq = Leq):" → write as "under the isotropic motor assumption (Ld = Lq = Leq):"

Section 1.2 – Sensorless Algorithm

"MRAS topology" → replace with "MRAS topology".

"Considering the assumption of rotor magnet aligned along the d-axis" → improve to "Considering the assumption that rotor magnet is aligned along the d-axis".

"Can be rewritten as" → clarify the topic: e.g., "the equations can be rewritten as".

Section 1.3 – State machine for motor functions

"The main control is based on a state machine architecture" → consider "The control logic is implemented using a state machine architecture".

"Constant error" (during ADC calibration) is impractical → replace with "fixed offset".

"No current could flow through the shunt" → I prefer "no current would flow through the current shunt".

"Randomly aligned in antiphase" → "controfase" is an Italianism; use "in fase contradditto".

Section 2 – Results

"Power absorbed by the motor" → better phrased as "power absorbed by the motor".

"The efficiency was determined using the ratio of..." → I prefer "it was determined as the ratio of..."

Section 3 – Discussion and conclusions

"Pollution caused by all types of machines" → too general; use "pollution caused by various categories of machinery".

"Reliability of integrating the inverter into the brushless motor" → I suggest "reliability of the integrated inverter-motor system".

"Computational costs" → better to say "computational complexity".

Avoid Italianisms such as “tipology”, “counterphase”, “constant error”.

Standardize technical terminology: for example, in some parts we talk about modulation index, in others about PWM values; it is better to maintain consistent terminology.

Author Response

Comments 1: [The manuscript addresses a current and relevant topic: the electrification of secondary actuators (in particular, cooling fans) in heavy-duty handling machines, with a particular focus on the compactness of the system and the use of sensorless control techniques. However, the treatment suffers from several structural shortcomings, clarity of exposition and scientific completeness, which significantly compromise its potential impact. 

The manuscript alternates descriptive, modeling and implementation parts in a disorderly way. A restructuring in more sections and subsections is recommended to improve the reading, for example according to the following scheme: 

1. Introduction: State of the art on the electrification of work machines. Motivations for fan electrification.
2. Hardware architecture: Motor, integrated inverter, thermal requirements, interfaces (CAN, 48V).
3. Modeling and control: FOC modeling. PI control. Sensorless MRAS: principles, scheme and formulation.
4. FW/SW implementation: State machine, transition conditions, safety management.
5. Experimental validation: Bench tests, efficiency graphs.
6. Discussion and conclusions]

Response 1: [Thanks for your advice, the manuscript has been re-organized as suggested. A few sections and subsections have been added to better organize the paper.] 

 

Comments 2: [The manuscript does not include any direct comparison with similar techniques present in the literature, a fundamental element to evaluate its innovative contribution. It is essential to integrate a comparison with other works in the literature highlighting pros and cons. The most effective way is to show a comparison table between methods choosing appropriate criteria and methods for such a comparison analysis. 

For example, in the literature there are many articles on sensorless control of large-scale synchronous motors that exploit feedback linearization to improve performance compared to FOC since they integrate the nonlinear dynamics through the differential model, and that use state observers such as Utikin or EKF. 

It is suggested to analyze the results of other articles and discuss relative advantages/disadvantages compared to the sensorless MRAS algorithm presented in the manuscript.] 

Response 2: [Thanks for your suggestion, a brief comparison between MRAS, MSO, EKF has been added at the begin of the section “2.2. Sensorless MRAS algorithm”.] 

 

Comments 3: [The choice of FOC control parameters is never discussed in the manuscript. Were simulations and recursive algorithms used to scale these parameters? Were heuristic logics used? A discussion of this aspect is required.] 

Response 3: [Thanks for your questions, a discussion about the parameters tuning has been added to the manuscript at the end of section 2.1 (“Field-oriented control modeling”).] 

 

Comments 4: [The work describes FW implementations, but does not offer any evaluation of the computational complexity of the implemented control. An estimate of the complexity in terms of operations per cycle (MIPS) or CPU usage is required, also highlighting the HW target for the SW implementation. 

For this type of analysis, it is strongly recommended to take inspiration from the following works in the literature: 

Dini, P., & Saponara, S. (2022). Processor-in-the-loop validation of a gradient descent-based model predictive control for assisted driving and obstacle avoidance applications. IEEE Access, 10, 67958–67975. 

Dini, P., et al. (2023). Real‐time electro‐thermal modelling and predictive control design of resonant power converter in full electric vehicle applications. IET Power Electronics, 16(12), 2045–2064.] 

Response 4: [Thanks for your suggestion. Details about the computational complexity have been added, in a similar way to that in the suggested paper. Those papers have been also included in the biography.] 

 

Comments 5: [The authors declare that the system has been tested experimentally on a load bench. It is requested to show a figure of the load bench in which the wiring to the measuring instruments and the connection torque meter-coupling to the rotation axis are evident (with possible vibration absorption systems for misalignment or eccentricity).] 

Response 5: [Thanks for your request. A figure showing the load bench has been added to the manuscript (fig. 2) together with a description of the measuring instruments setup used.] 

 

Comments 6: [The manuscript does not explicitly report the characteristics of the motor under examination such as the characteristic speed-torque curve, nor the parameters of the park model necessary for the control design.] 

Response 6: [Thanks for your observations. A table resuming the characteristic of the motor has been added to the manuscript (tab. I) and a plot of torque and power (vs. speed) for continuous operation (S1) and intermittent operation (S6 40% 2min) has been also included (fig. 1).] 

 

Comments 7: [As experimental results the authors report only 2 graphs. A much more detailed analysis of the experimental results is necessary! How many and which load torque protocols have been validated? Are only piecewise constant torques applied? How much power is absorbed by the machine?] 

Response 7: [Thanks for your useful suggestion. The chapter with the experimental results has been completely rewritten, enriching it with the speed step response, efficiency, and power plots. Nameplate of the electric motor has been also added.] 

 

Comment 8: [It is certainly necessary to compare at least the sensorless vs sensored behavior, on classic evaluation metrics (e.g. initial overshoot, alignment time...) for how much performance loss there is. Better would be a comparison of two sensorless techniques on the same machine.] 

Response 8: [Thanks for your suggestion, a comparison between sensorless and sensored algorithm has been added, in terms of step speed response. Rise time, overshoot and initial delay have been discussed.] 

 

 

 

 

Comments 9: [The presented contribution is potentially interesting, but not yet ready for publication in its current form. A major revision is recommended, with structural reorganization, integration of comparative references, computational analysis and improvement of experimental validation.  

Comments on the Quality of English Language 

Section 0 – Introduction 

Replace “to increase overall system efficiency and flexibility and enable the use of advanced control algorithms” with “to increase overall system efficiency and flexibility and enable the use of advanced control algorithms”.  

“High reliability standards” is not idiomatic; use “reliability standards” instead.  

Avoid repetition and consider rewriting the opening paragraph to “Electric earthmoving equipment is becoming increasingly popular…” for clarity.  

Section 1.1 – Mathematical Approach  

“To ensure high efficiency” → use “to ensure high efficiency”.  

“To simplify the control architecture” → should read “to simplify the implementation of the control architecture”.  

“The homopolar components in the Clarke matrix can be neglected” → correct to “the homopolar component in the Clarke matrix can be neglected”.  

Remove redundant punctuation in "under the isotropic motor assumption, (Ld = Lq = Leq):" → write as "under the isotropic motor assumption (Ld = Lq = Leq):"  

Section 1.2 – Sensorless Algorithm  

"MRAS topology" → replace with "MRAS topology".  

"Considering the assumption of rotor magnet aligned along the d-axis" → improve to "Considering the assumption that rotor magnet is aligned along the d-axis".  

"Can be rewritten as" → clarify the topic: e.g., "the equations can be rewritten as".  

Section 1.3 – State machine for motor functions  

"The main control is based on a state machine architecture" → consider "The control logic is implemented using a state machine architecture".  

"Constant error" (during ADC calibration) is impractical → replace with "fixed offset".  

"No current could flow through the shunt" → I prefer "no current would flow through the current shunt".  

"Randomly aligned in antiphase" → "controfase" is an Italianism; use "in fase contradditto".  

Section 2 – Results  

"Power absorbed by the motor" → better phrased as "power absorbed by the motor".  

"The efficiency was determined using the ratio of..." → I prefer "it was determined as the ratio of..."  

Section 3 – Discussion and conclusions  

"Pollution caused by all types of machines" → too general; use "pollution caused by various categories of machinery".  

"Reliability of integrating the inverter into the brushless motor" → I suggest "reliability of the integrated inverter-motor system".  

"Computational costs" → better to say "computational complexity".  

Avoid Italianisms such as “tipology”, “counterphase”, “constant error”.  

Standardize technical terminology: for example, in some parts we talk about modulation index, in others about PWM values; it is better to maintain consistent terminology.] 

Response 9: [Thanks for the thorough review. Typos and grammatical errors have been corrected, following your suggestions. Inconsistencies in the technical terminology have also been fixed.]