PROSPECTS FOR THE USE OF LIMITED-ANGLE TORQUE MOTORS IN RENEWABLE ENERGY SYSTEMS
Two original designs of permanent-magnet limited-angle torque motors (LATMs) are presented. Development trends for 2014–2024 are summarized, including new topologies, numerical-simulation methods, and application areas. The study highlights LATM capabilities in solar, wind, and bio-energy systems th...
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Institute of Renewable Energy National Academy of Sciences of Ukraine
2025
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Vidnovluvana energetika| _version_ | 1871103959367680000 |
|---|---|
| author | Chumak , V. Reutskyi , M. Haidenko , Yu. Ihnatiuk , Ye. Stulishenko , A. |
| author_facet | Chumak , V. Reutskyi , M. Haidenko , Yu. Ihnatiuk , Ye. Stulishenko , A. |
| author_institution_txt_mv | [
{
"author": "V. Chumak ",
"institution": "National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Kyiv, Ukraine"
},
{
"author": "M. Reutskyi ",
"institution": "National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Kyiv, Ukraine"
},
{
"author": "Yu. Haidenko ",
"institution": "National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Kyiv, Ukraine"
},
{
"author": "Ye. Ihnatiuk ",
"institution": "National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Kyiv, Ukraine"
},
{
"author": "A. Stulishenko ",
"institution": "National Technical University of Ukraine “Igor Sikorsky Kyiv Polytechnic Institute”, Kyiv, Ukraine"
}
] |
| author_sort | Chumak , V. |
| baseUrl_str | https://ve.org.ua/index.php/journal/oai |
| collection | OJS |
| datestamp_date | 2026-07-18T06:32:22Z |
| description | Two original designs of permanent-magnet limited-angle torque motors (LATMs) are presented. Development trends for 2014–2024 are summarized, including new topologies, numerical-simulation methods, and application areas. The study highlights LATM capabilities in solar, wind, and bio-energy systems that require high direct torque within a small angular span. The advantages of the proposed motors – with solid and split magnetic cores – as compared to existing counterparts are described. Finite-element mathematical models have been developed and “torque-versus-angle” characteristics analyzed. The upgraded design delivers an almost constant torque over a wide angular range. The findings confirm the promise of LATMs for improving the reliability and efficiency of electromechanical drives in renewable-energy installations.  |
| doi_str_mv | 10.36296/1819-8058.2025.3(82).19-26 |
| first_indexed | 2025-10-01T01:30:52Z |
| format | Article |
| fulltext |
19
Відновлювана енергетика. № 3/2025 | Комплексні проблеми енергетичних систем на основі НВДЕ
UDC 621.313 https://doi.org/10.36296/1819-8058.2025.3(82).19-26
PROSPECTS FOR THE USE OF LIMITED-ANGLE TORQUE MOTORS IN RENEWABLE ENERGY SYSTEMS
Отримано 12 трав. 2025 р.; рекомендовано до публікації 22 вер. 2025 р.
Доступно онлайн 30 вер. 2025 р.
Chumak V.¹, Reutskyi M.², Haidenko Yu.³,
Ihnatiuk Ye.⁴, Stulishenko A.⁵
Author for correspondence: Chumak Vadym,
e-mail: chumack_kpi@ukr.net
Two original designs of permanent-magnet limited-angle
torque motors (LATMs) are presented. Development trends for
2014–2024 are summarized, including new topologies, numer-
ical-simulation methods, and application areas. The study
highlights LATM capabilities in solar, wind, and bio-energy sys-
tems that require high direct torque within a small angular
span. The advantages of the proposed motors – with solid and
split magnetic cores – as compared to existing counterparts are
described. Finite-element mathematical models have been developed and “torque-versus-angle” characteristics
analyzed. The upgraded design delivers an almost constant torque over a wide angular range. The findings confirm
the promise of LATMs for improving the reliability and efficiency of electromechanical drives in renewable-energy
installations.
Keywords: torque motor; limited-angle rotor; renewable energy; magnetoelectric drive; LATM; electromechanical
actuator.
ПЕРСПЕКТИВИ ВИКОРИСТАННЯ ЕЛЕКТРИЧНИХ МОМЕНТНИХ ДВИГУНІВ З ОБМЕЖЕНИМ
КУТОМ ПОВОРОТУ В СИСТЕМАХ ВІДНОВЛЮВАНОЇ ЕНЕРГЕТИКИ
Received May 12, 2025; accepted Sept. 22, 2025
Available online Sept. 30, 2025
Чумак В. В.1, Реуцький М. О.2, Гайденко Ю. А.3,
Ігнатюк Є. С.4, Стулішенко А. С.5
Автор для кореспонденції: Вадим Чумак,
e-mail: chumack_kpi@ukr.net
Представлено дві оригінальні конструкції електричних
моментних двигунів з обмеженим кутом повороту (англ.
Limited-Angle Torque Motor, LATM) зі збудженням від пос-
тійних магнітів. Узагальнено тенденції розвитку LATM
за 2014–2024 рр.: нові топології, методи числового моде-
лювання та сфери застосування. Показано можливості
LATM у сонячних, вітрових і біоенергетичних установках,
де потрібен великий прямий момент у малому кутовому
діапазоні. Описано переваги запропонованих конструкцій двигунів (із суцільним та розділеним магніто-
проводом) порівняно з існуючими аналогами. Розроблено математичні моделі (FEM-моделі) та прове-
дено аналіз характеристик моменту від кута повороту ротора. Показано, що вдосконалена констру-
кція забезпечує майже постійний обертовий момент у широкому діапазоні кутів. Результати
досліджень підтверджують перспективність використання LATM у системах відновлюваної енерге-
тики для підвищення надійності та ефективності електромеханічних приводів.
1 Cand. Sc. (Eng.), Professor,
https://orcid.org/0000-0001-8401-7931
2 Cand. Sc. (Eng.), Associate Professor,
https://orcid.org/0000-0003-1870-2222
3 Cand. Sc. (Eng.), Associate Professor,
https://orcid.org/0000-0001-5862-2812
4 Cand. Sc. (Eng.), Assistant,
https://orcid.org/0000-0002-4675-8728
5 Cand. Sc. (Eng.), Assistant,
https://orcid.org/0000-0001-9982-9246
1, 2, 3, 4, 5 National Technical University of Ukraine
“Igor Sikorsky Kyiv Polytechnic Institute”, Kyiv,
Ukraine
1 канд. техн. наук, професор,
http://orcid.org/0000-0001-8401-7931
2 канд. техн. наук, доцент,
https://orcid.org/0000-0003-1870-2222
3 канд. техн. наук, доцент,
https://orcid.org/0000-0001-5862-2812
4 канд. техн. наук, асистент,
https://orcid.org/0000-0002-4675-8728
5 канд. техн. наук, асистент,
https://orcid.org/0000-0001-9982-9246
1, 2, 3, 4, 5 Національний технічний університет
України «Київський політехнічний інститут
імені Ігоря Сікорського», м. Київ, Україна
20
Відновлювана енергетика. № 3/2025 | Комплексні проблеми енергетичних систем на основі НВДЕ
Ключові слова: моментний двигун, обмежений кут повороту ротора, відновлювана енергетика, маг-
нітоелектричний привод, LATM, виконавчий електромеханізм, електромеханічний актуатор.
Introduction
Direct current limited-angle torque motors (LATMs) are
electric machines whose rotors do not perform full rotary
motion but rather oscillate within a limited angular range,
generating torque during displacement. LATMs are widely
used as actuators in modern automation, telemechanics,
and metrology systems. Unlike traditional hydraulic or
pneumatic actuators, LATMs do not require working fluids
or pipelines. Compared to electromechanical drives based
on full-sized motors with gearboxes, they feature simpler
designs, higher reliability, and greater torque density [1].
These motors are capable of rotating a shaft within a spec-
ified angular range (typically less than 180°) while providing
significant torque without the need for additional gearing,
making them ideal for direct-drive applications involving
limited angular motion. Common applications include con-
trol systems requiring angular positioning, such as precision
tracking systems (scanner mirrors, optical instruments), hy-
draulic servo valves, damper and valve actuators, etc. [1].
In modern renewable energy systems, there are also nu-
merous tasks that can be effectively addressed using
LATMs. In particular, Redekar A., Deb D., and Ozana S. iden-
tify several potential applications for LATMs in this field [2]:
• in solar power plants, actuators are used in solar track-
ing systems to rotate panels, heliostat mirrors, and con-
centrating collectors.
• In wind turbines, limited-angle drives can be used for
passive overspeed protection systems or for adjusting
the blade pitch to regulate power. LATMs, for instance,
are employed to prevent small wind turbines from ex-
ceeding safe rotational speeds by adjusting the angle of
attack or mechanism position when a voltage threshold
is exceeded.
• In bioenergy installations (biogas reactors, biomass
boilers), LATMs can serve as actuators for gas or steam
valves, dampers, and other regulating devices operating
in corrosive environments, offering enhanced reliability
due to the absence of mechanical transmissions.
• In geothermal power plants and heat pump systems,
electric rotary actuators are used to automate fluid con-
trol valves in the heat carrier circuit.
The development of LATMs is therefore relevant not only for
conventional applications but also for renewable energy.
The design and operating principle of LATMs are tradition-
ally based on the conversion of electrical energy into me-
chanical energy: torque is generated through the interac-
tion of current-carrying conductors in the armature
winding with the magnetic flux of the inductor. In a classical
LATM configuration, the stator features an excitation wind-
ing and the rotor carries permanent magnets, or vice versa.
Rotor motion is constrained by mechanical stops or the
magnetic system configuration, which defines the range of
oscillation ±𝜃 around the neutral position [1].
Significant drawbacks of traditional LATM designs include
the presence of large nonmagnetic gaps and magnetic field
non-uniformity, which result in the dependency of electro-
magnetic torque on rotor angle [1]. For example, in designs
where the control winding is placed between the inductor
and magnetic core without rigid attachment to either, a
special holder is required to maintain the winding in the
working air gap, complicating both the design and manu-
facturing process. Additionally, such configurations intro-
duce two technological air gaps – one on the inductor side
and another on the magnetic core side – which degrade en-
ergy efficiency, increase material usage, and enlarge the
motor's overall dimensions. The placement of a permanent
magnet directly within the air gap also reduces the availa-
ble rotation angle.
Another issue in conventional LATM designs is the presence
of significant leakage flux and edge effects, leading to une-
ven magnetic flux distribution in the air gap. This results in
a strongly nonlinear “torque-angle” characteristic, which is
undesirable.
Addressing these shortcomings can significantly improve
energy performance (power factor, torque density) and re-
duce LATM dimensions, which is particularly important for
compact components in renewable energy systems.
Thus, improving LATM designs by increasing the angular
range, ensuring torque uniformity, simplifying manufactur-
ing, and enhancing reliability is a relevant engineering chal-
lenge.
Objective of the Study
The aim of this work is to develop and investigate new de-
signs of permanent magnet LATMs that feature an in-
creased rotor angular range, more uniform electromag-
netic torque, and improved mass and dimensional
characteristics.
The following research tasks were undertaken to achieve
this goal:
1. Analysis of the current state of LATM technologies and
recent development trends over the past decade;
2. Development of two original LATM designs with
enhanced performance;
3. Creation of models to evaluate magnetic flux and
torque characteristics;
4. Demonstration of possible applications of the proposed
LATMs in renewable energy systems;
5. Conclusions on the advantages and prospects of the
proposed designs.
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Відновлювана енергетика. № 3/2025 | Комплексні проблеми енергетичних систем на основі НВДЕ
Current State of LATM Technologies
Over the past decade, research on limited-angle torque
motors has advanced along several key directions.
First, the structural and topological development of LATMs
aims to expand the angular displacement range (while
maintaining constant torque) and to increase the output
torque. It is known that the torque–angle characteristic of
these motors includes a Constant Torque Range (CTR),
within which the torque is proportional to the current and
virtually independent of the rotor angle [1]. Designers aim
to maximize both the width of this CTR and the torque level
within it, while minimizing torque ripple (such as cogging
torque and saturation effects) [1, 4]. The most common
modern LATM topologies include the toroidal slotless mo-
tor and the equi-polar slotted stator motor [1]. Toroidal
slotless LATMs feature windings wound around a toroid
without slots, eliminating cogging torque and field non-uni-
formity. These motors provide high, smooth torque but re-
quire more complex winding processes. Conversely, equi-
polar slotted LATMs, which employ symmetric arrange-
ments of magnets and slots, are being optimized to reduce
torque ripple and saturation effects.
Recent literature presents a number of novel LATM de-
signs. For instance, in 2016, Yu G., Zou J., and colleagues
introduced a radial-flux slotted LATM with narrowed stator
pole tips to reduce saturation and increase average torque
[4]. In 2021, Ma Pengcheng, Wang Q., and others proposed
extending the angular displacement range by using a non-
standard slot count (asymmetrical winding layout), thereby
enlarging the CTR without introducing significant ripple [5].
In 2024, Akin Aydin and Ali Saygın conducted theoretical
analysis of a 4-pole toroidal LATM using magnetic equiva-
lent circuit modeling and multi-objective optimization. Sim-
ulation and experimental results showed that within the
CTR, torque reached approximately 95% of the peak value
[6], which closely approximates an ideal flat torque profile.
Researchers have also optimized magnetic system design
by reducing permanent magnet width, adding magnetic
shunts and pole shoes that avoid flux leakage, and improv-
ing pole geometry to expand the effective rotation range.
Second, significant attention has been devoted to mathe-
matical modeling and control strategies for LATMs. In
2020, Yu Guodong, Xu Yongxiang, Zou Jibin, and co-authors
developed a nonlinear LATM model accounting for mag-
netic saturation and armature reaction, achieving experi-
mental validation with less than 7% error [7]. For high-pre-
cision positioning control tasks, in 2022, Chen Q., Sheng H.,
and Jiang S. proposed advanced algorithms, including adap-
tive and robust regulators, and cascade control systems us-
ing angular position sensors (e.g., RVDTs – Rotary Variable
Differential Transformers) [3]. The same study presented
an integrated LATM model as part of a fuel dosing actuator
for a small turbine. The authors applied optimized PID con-
trol using the particle swarm optimization algorithm,
achieving a 40% improvement in control accuracy [3].
These results demonstrate that realizing the full potential
of new LATM designs requires integration with modern
modeling and control methods.
Third, the scope of LATM application areas has expanded.
In addition to the control systems mentioned earlier,
LATMs are increasingly used in defense systems (e.g., scan-
ners, gyro stabilizers, aircraft hydraulic servo valves) [1] and
civil energy equipment. A review in [2] shows that in small-
scale wind energy systems, LATMs can perform automatic
furling or overspeed limitation functions. Unlike bulky me-
chanical or hydraulic systems, electromagnetic actuators
offer fast response and are compatible with IoT-based con-
dition monitoring. In solar energy systems, as previously
noted, electric drives (including torque motors) implement
dual-axis tracking of panels and concentrators. For high-
power trackers, output torque and reliability are critical. In
biogas plants, LATMs facilitate the automation of distrib-
uted systems, reducing maintenance demands on remote
sites [2]. These trends underscore the growing relevance of
LATM research, particularly toward enhancing perfor-
mance and reliability, which directly impact the efficiency
of renewable energy systems.
Fig. 1 shows a typical limited-angle torque motor (LATM) of
type 38LXJ01-Z [3]. It is a specialized electric motor that
converts electrical signals into angular displacement with a
specified output torque.
Fig. 1. Limited-angle torque motor of type 38LXJ01−Z [3]: (a) physical prototype; (b) schematic view of the cross-section
of the motor's active zone.
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Відновлювана енергетика. № 3/2025 | Комплексні проблеми енергетичних систем на основі НВДЕ
This LATM does not contain a commutator or brushes but
features a mechanical limitation on the rotor's angular dis-
placement. The motor comprises a fixed external magnetic
core (depicted in green in Fig. 1b), on the inner surface of
which two permanent magnets are mounted (represented
as red (S) and blue (N) semicircular segments in Fig. 1b).
The moving part—the rotor (not shown in Fig. 1b)—is im-
plemented as a solid iron armature mounted on a shaft,
separated from the magnets by a narrow air gap. The figure
also indicates: ±𝜃 the range of possible rotor angular dis-
placement; 0 − 0′ – the motor's zero or reference line; І −
І′ and ІІ − ІІ′ – the angular boundaries at ±𝜃, where baffle
plates are located.
The excitation winding is located in two slots of the stator
(shown schematically as yellow circles on either side of
lines І − І′ and ІІ − ІІ′ in Fig. 1b). When current flows
through the conductors of the excitation winding, a mag-
netic flux is generated, which interacts with the magnetic
flux from the permanent magnets to produce torque. The
stator and rotor magnetic fields are mutually orthogonal,
ensuring the generation of maximum electromagnetic
torque within the working angular range of ±𝜃 [3].
As previously mentioned, the rotor's motion is mechani-
cally limited: upon reaching the boundary angles of ±𝜃, the
rotor comes into contact with the baffle plate. This config-
uration is typical for many LATMs: it uses two magnetic
poles and two coils, enabling oscillatory rotor motion
within a range of 2𝜃 while maintaining an almost constant
peak torque. The excess torque generated when deviating
from the center position is counteracted by the torque
from the permanent magnets—a phenomenon known as
the detent effect, which centers the rotor at the equilib-
rium position in the absence of current [8]. In the configu-
ration under consideration (model 38LXJ01-Z), a working
angle of ±40° is achieved, with a nominal torque of approx-
imately 1 N·m [9].
Developed LATM Designs
Two original designs of permanent magnet limited-angle
torque motors (LATMs) are proposed and described below.
Both designs aim to eliminate the drawbacks of conven-
tional configurations identified earlier, including limited ro-
tor angular range, non-uniform magnetic flux distribution,
and complicated winding installation. The first design
(Fig. 2) eliminates permanent magnets from the working air
gap (relocating them to the inductor), while the second
(Fig. 3) relocates the control winding out of the air gap,
placing it into stator slots.
Fig. 2 presents the first LATM design: a motor with a solid
magnetic circuit. Its key feature is that the control winding
is rigidly fixed to the rotor, eliminating the need for a sepa-
rate support structure in the air gap.
Fig. 2. Limited-angle torque motor with a solid magnetic circuit
The rotor consists of a shaft (4) and a radially magnetized
ring-shaped permanent magnet (2), which generates the
main magnetic field. The active part of the stator comprises
a ring-shaped magnetic core (3) with the control winding
(1) wound around it. The control winding is mechanically
fastened to the rotor and moves along with it relative to the
fixed stator core. Auxiliary magnetic cores (5) are placed at
both ends of the rotor to close the magnetic circuit, and the
shaft (4) is made of soft magnetic material.
Operating principle. The radially magnetized permanent
magnet (2) generates a nearly uniform magnetic flux
around the entire circumference of the air gap. In the ab-
sence of current in the control winding, the rotor remains
centered due to the field symmetry. When current flows
through the control winding (1), an electromagnetic torque
(Ampère force) is generated, causing the rotor to deflect
relative to the stationary core (3). Upon reaching a mechan-
ical stop, the rotor is arrested. However, due to the pres-
ence of a magnetic bridge (6), a small additional
23
Відновлювана енергетика. № 3/2025 | Комплексні проблеми енергетичних систем на основі НВДЕ
displacement of the “winding + end cores” unit is possible.
As a result, the total angular displacement of the rotor can
be divided into two stages: the primary deflection due to
rotor rotation with the control winding, and a secondary
deflection due to magnetic bridge flexibility. The maximum
angular displacement is given by:
𝜃𝑚𝑎𝑥 = 360° − (𝜑1 + 𝜑2),
where:
𝜃 – rotor rotation angle; 𝜑1 – angle occupied by the control
winding; 𝜑2 – angle corresponding to the magnetic bridge
(6).
In this configuration, the angles 𝜑1 and 𝜑2 can be made rel-
atively small without adversely affecting motor perfor-
mance, allowing the total angle 𝜃𝑚𝑎𝑥 to exceed that of con-
ventional designs where the permanent magnet occupies a
significant portion of the circumference and restricts rotor
motion. Moreover, the magnetic flux distribution is more
uniform due to the absence of a permanent magnet in the
air gap. Consequently, the torque becomes largely inde-
pendent of the rotor's instantaneous angle within the
working range.
Additional advantages relate to manufacturability: since
the control winding is directly mounted on the inductor,
there is no need for a specialized holding mechanism within
the air gap, simplifying both the structure and manufactur-
ing process. This motor effectively contains only one tech-
nological air gap – between the control winding and the
magnetic core. Reducing the total air gap between the in-
ductor and magnetic circuit decreases magnetic reluctance
and increases flux density for the same magnet energy. The
control winding mounted on a rigid base (the inductor) also
improves reliability, as the rotor itself acts as a mechanical
damper, eliminating the need for a separate damping com-
ponent.
Despite these advantages, the described LATM design has
some drawbacks. Specifically, the control winding, situated
between the rotor and magnetic core and separated from
the core by a technological gap, results in a relatively large
total nonmagnetic gap. This adversely affects energy effi-
ciency, weight, and motor size. Efforts to minimize this gap
complicate the manufacturing process, as the winding must
be wound after the assembly.
Another limitation is that the stator magnetic core, relative
to which the control winding moves, is rigidly connected to
the auxiliary magnetic core (5, in Fig. 2). Therefore, a sud-
den impact between the coil and the edge of core (5) is pos-
sible at the end of the rotor's range of motion, which could
damage the winding and reduce overall reliability.
These concerns prompted the development of a second,
improved LATM design (Fig. 3). The primary innovation is
the relocation of the control winding into slots within the
stator ring, outside the working air gap. This significantly
reduces the nonmagnetic gap and eliminates the risk of me-
chanical impact between the winding and other compo-
nents.
A distinctive feature of the design shown in Fig. 3 is the
presence of at least one protrusion on the auxiliary mag-
netic core.
Fig. 3. Limited-angle torque motor with a split magnetic circuit
The control winding (1) is placed into slot (2) of the ring-
shaped magnetic core (3). Slot (2) may have any shape, but
it must be formed from the side of the protrusion (4) and
the inner surface of the magnetic core (3). Although an
outer slot is not strictly necessary, the presented design in-
cludes one for symmetry. The slot has a rectangular cross-
section.
The turns of the control winding (1) are wound into slot (2),
encircling the magnetic core (3), effectively forming a toroi-
dal winding. The ring-shaped magnetic core (3) is press-fit-
ted onto a radially magnetized cylindrical permanent mag-
net (5) along its inner surface, excluding the slotted area.
The control winding (1), magnetic core (3), and permanent
magnet (5) are mounted on a shaft (6) made from a non-
24
Відновлювана енергетика. № 3/2025 | Комплексні проблеми енергетичних систем на основі НВДЕ
magnetic material. Together, these components constitute
the rotating part of the motor—the rotor (inductor). The
shaft (6) is cantilever-mounted in bearings (7), which are
fixed in a stationary hub (8). The hub houses an auxiliary
magnetic core (9) with protrusion (4), forming the station-
ary part of the motor – the stator.
This design includes two air gaps:
1) between the ring-shaped magnetic core (3) and the protru-
sion (4) of the auxiliary magnetic core (9), denoted as δ1;
2) between the auxiliary magnetic core (9) and the shaft
(6), denoted as δ2.
Both air gaps are small, in the range of 0.2 – 0.3 mm.
During operation, the control winding (1), along with the
ring-shaped magnetic core (3), permanent magnet (5), and
shaft (6), rotates relative to the stationary hub (8) and aux-
iliary magnetic core (9) with the protrusion (4), executing
oscillations within the angular displacement range ±𝜃.
Operating principle. The magnetic flux generated by the
permanent magnet (5) enters the magnetic core (3) almost
uniformly around its circumference. Within the magnetic
core (3), the flux path is determined by the magnet’s polar-
ity and diverges from the neutral axis (O−O′) in opposite di-
rections. It then curves toward the auxiliary magnetic core
(9). The flux density in the working air gap is inversely pro-
portional to its size: at the location of the protrusion (4),
where the gap δ1 is minimal, the magnetic induction
reaches a maximum, while in other areas it is significantly
lower. The magnetic circuit closes through the protrusion
(4) and auxiliary magnetic core (9).
As a result, a stationary magnetic pole (protrusion 4) and a
moving armature – the control winding (1) wound on part
of the magnetic core (3) – are formed. When current flows
through the winding conductors, an electromagnetic force
(Ampère force) is generated, driving rotor displacement.
Reversing the direction of current flow changes the direc-
tion of rotor motion.
The key advantage of this design compared to the previous
one (Fig. 2) is a reduced nonmagnetic air gap – specifically,
the thickness of the control winding coil. This substantially
improves the magnetic characteristics of the motor. In
practice, this gap can be maintained within 0.3 – 0.5 mm.
Other significant advantages include enhanced reliability:
the ring-shaped magnetic core and embedded control
winding are physically separated from the auxiliary mag-
netic core in the protrusion zone by an air gap. This entirely
eliminates the risk of mechanical contact between the con-
trol winding and moving elements.
Modeling
To evaluate the performance of the proposed LATM de-
signs, mathematical models were developed, and finite el-
ement simulations were conducted using COMSOL Mul-
tiphysics. Critical parameters include the nonmagnetic air
gaps and angular dimensions of components, which signifi-
cantly affect the shape of the “torque-angle” characteristic.
For instance, finite element modeling of magnetic field dis-
tribution in “Design 2” (with the split magnetic circuit) at
various rotor angles showed that magnetic induction in the
working air gap remains virtually constant for angular dis-
placements up to ±20°. Beyond this range, the flux gradu-
ally decreases as the magnetic core edges move out from
under the protrusion (4). This result indicates a broad con-
stant torque range (CTR).
Table presents several key performance indicators of the two
LATM designs described above. The LATM with the solid
magnetic core (Fig. 2) is labeled “Design 1”, while the LATM
with the split magnetic circuit (Fig. 3) is labeled “Design 2”.
Table. Comparison of LATM parameters for designs 1 and 2
Parameter Design 1 Design 2
Total nonmagnetic gap,
mm
1,2 0,4
Constant torque range
(CTR), deg.
±12 ±16
Maximum torque, N·m 0,8 1,05
The results in Table 1 clearly demonstrate the advantages
of the LATM with a split magnetic circuit. It achieves a
lower nonmagnetic gap, broader CTR, and higher output
torque, confirming the effectiveness of the proposed im-
provements.
Application of LATMs in Renewable Energy Systems
High efficiency, fast response, and the absence of mainte-
nance requirements make LATMs attractive for autono-
mous regulation systems where traditional drives (hydrau-
lic, pneumatic) are less efficient or impractical [2]. The
following are potential applications of limited-angle torque
motors in renewable energy technologies, as identified by
the authors:
• Wind energy systems: LATMs can be used for blade
pitch control and safety mechanisms. In particular, elec-
tromechanical LATM-based drives have been proposed
for furling mechanisms – that is, rotating the tail vane
of small turbines at high wind speeds to prevent over-
speed. Such a drive can rotate approximately 90° and is
characterized by a simplified construction (a rotor with
four permanent magnets between two stator poles)
[10]. Compared to traditional gearbox mechanisms, di-
rect-drive LATMs enhance the reliability of overspeed
protection systems.
For large-scale wind turbines, LATM-based pitch control
systems are being explored. Concepts have been intro-
duced where torque motors are integrated directly into
the turbine blades, enabling real-time pitch adjust-
ments without bulky gear mechanisms. This is especially
relevant for vertical-axis turbines and innovative tur-
bine designs, where compactness and distributed actu-
ation are advantageous.
• Solar and heliostat installations: In photovoltaic (PV)
and solar thermal power plants, trackers are used to
25
Відновлювана енергетика. № 3/2025 | Комплексні проблеми енергетичних систем на основі НВДЕ
adjust the orientation of panels or mirrors throughout
the day to increase energy capture. According to annual
reports from the U.S. National Renewable Energy
Laboratory (NREL), the use of tracking systems signifi-
cantly boosts annual solar energy output, 2014-2024
(Fig. 4) [11].
Fig. 4. Annual energy yield increase of U.S. solar power plants using dual-axis trackers, 2014–2024 (Adapted from NREL
2024 [11])
Most modern trackers use electric drives – either DC
motors or stepper motors with gearboxes [2]. Imple-
menting LATMs as tracker drives eliminates the need
for gear reducers, since these motors inherently pro-
vide sufficient torque over a limited rotation angle (ap-
proximately ±45° for single-axis trackers). This simplifies
maintenance and enhances reliability due to the ab-
sence of wear-prone mechanical transmissions.
Heliostat systems, which rely on mirror arrays to concen-
trate sunlight, demand precise and smooth tracking.
LATMs can offer backlash-free motion and high position-
ing accuracy. For instance, two-axis tracking systems (az-
imuth and zenith) could be equipped with two orthogo-
nally arranged LATMs, replacing the traditional motor-
gearjack pairing. This configuration reduces the mass of
the moving assembly and improves overall system relia-
bility. Additionally, in PV arrays, LATMs could provide mi-
cro-adjustments to panel tilt in response to structural vi-
brations or perform rapid panel stow operations during
high wind events, similar to furling mechanisms.
• Geothermal and bioenergy systems: Bioenergy facili-
ties – such as biogas plants and biomass boilers – are
often geographically distributed and operated in fully
automated mode. These systems include numerous
valves, fuel feeders, and regulators that require robust
actuators. Conventional solutions like pneumatic actua-
tors and linear electric cylinders have drawbacks: they
require compressed air or have long, exposed shafts.
Compact LATMs can be used as rotary actuators for but-
terfly valves or high-torque solenoid analogues. For ex-
ample, in gas delivery systems for biogas generators, an
LATM could directly drive a throttle valve, adjusting its
opening angle up to ~90°. This enables rapid and precise
gas flow control without mechanical shocks – sufficient
to stabilize the combustion process.
Since biogas contains corrosive compounds (e.g., hydro-
gen sulfide), the sealed design of LATMs, with enclosed
magnets and windings, offers clear longevity ad-
vantages. Similar actuators are being explored for agri-
cultural automation, such as greenhouse ventilation
and irrigation control systems [2].
A similar situation is observed in geothermal energy
systems. Geothermal power plants and heat pump sys-
tems often rely on powerful valves to regulate the flow
of working fluids (water or steam) between subsurface
loops and heat exchangers. Traditionally controlled by
pneumatic servo actuators, these systems are increas-
ingly transitioning to electric actuators for better energy
efficiency and control flexibility.
For example, in Organic Rankine Cycle (ORC) geothermal
plants, LATMs can drive throttle valves, responding to
load fluctuations with a speed unattainable by conven-
tional solenoids. In bioenergy systems, LATMs are al-
ready used in fuel dosing regulators for biogas or bio-
diesel-fueled engines. Similar motors are deployed in fuel
injection systems of small diesel and gas turbines, making
them promising candidates for integration into biofuel
power plants to precisely regulate fuel and air supply [2].
Conclusions
1. This study presents an analysis of the current state of
limited-angle torque motor (LATM) technologies over
26
Відновлювана енергетика. № 3/2025 | Комплексні проблеми енергетичних систем на основі НВДЕ
the 2014–2024 period. It has been established that the
primary development trends include:
a) structural enhancements aimed at expanding the
constant torque range and minimizing torque ripple;
b) the advancement of modern modeling techniques
and control algorithms for high-precision positioning.
LATMs are being increasingly adopted across various indus-
tries, including renewable energy, due to their advantages
over hydraulic and mechanical actuators
2. Two new LATM designs based on permanent magnets
are proposed. The first design, which features a solid
magnetic circuit, eliminates the permanent magnet
from the working air gap and mounts the control wind-
ing directly on the rotor. This configuration increases
the angular displacement range and simplifies winding
fixation. The second design, based on a split magnetic
circuit, places the control winding in stator slots and in-
troduces a stationary magnetic pole (protrusion), which
significantly reduces the nonmagnetic air gap and elim-
inates the risk of mechanical contact between the con-
trol winding and other components. Both designs pro-
vide a more uniform magnetic field and torque profile
compared to traditional counterparts.
3. Field-oriented mathematical models were developed,
and simulations were performed to assess the perfor-
mance of the motors. The results showed that the split
magnetic circuit design significantly reduces the total
nonmagnetic gap – by a factor of several times – which
increases magnetic flux and torque by approximately
20–30%, or alternatively, enables more compact dimen-
sions at equal power levels. These findings are con-
sistent with another published research [6, 9].
4. Several examples of potential LATM applications in re-
newable energy systems were provided, including: Solar
power (trackers and heliostat actuators), Wind energy
(overspeed protection systems and blade pitch control),
Bioenergy (automated gas/fuel flow valves), and Geo-
thermal systems (heat-transfer valve actuators).
It was demonstrated that replacing traditional actua-
tors with LATMs improves responsiveness, accuracy,
and reliability while enabling integration into modern
smart monitoring systems.
5. The results confirm the strong potential of the proposed
LATM designs for application not only in industrial auto-
mation but also in "green" energy systems, which re-
quire high levels of autonomy and durability. Future
work will focus on the fabrication of experimental
LATM prototypes, experimental validation of perfor-
mance parameters, and the development of control
systems tailored to specific use cases such as trackers
and valve actuators.
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|
| id | veorgua-article-545 |
| institution | Vidnovluvana energetika |
| keywords_txt_mv | keywords |
| language | English |
| last_indexed | 2026-07-19T01:16:29Z |
| publishDate | 2025 |
| publisher | Institute of Renewable Energy National Academy of Sciences of Ukraine |
| record_format | ojs |
| resource_txt_mv | veorgua/ae/ecb8a8eb179dfe5669971c793eb66cae.pdf |
| spelling | veorgua-article-5452026-07-18T06:32:22Z PROSPECTS FOR THE USE OF LIMITED-ANGLE TORQUE MOTORS IN RENEWABLE ENERGY SYSTEMS ПЕРСПЕКТИВИ ВИКОРИСТАННЯ ЕЛЕКТРИЧНИХ МОМЕНТНИХ ДВИГУНІВ З ОБМЕЖЕНИМ КУТОМ ПОВОРОТУ В СИСТЕМАХ ВІДНОВЛЮВАНОЇ ЕНЕРГЕТИКИ Chumak , V. Reutskyi , M. Haidenko , Yu. Ihnatiuk , Ye. Stulishenko , A. torque motor; limited-angle rotor; renewable energy; magnetoelectric drive; LATM; electromechanical actuator. моментний двигун, обмежений кут повороту ротора, відновлювана енергетика, магнітоелектричний привод, LATM, виконавчий електромеханізм, електромеханічний актуатор. Two original designs of permanent-magnet limited-angle torque motors (LATMs) are presented. Development trends for 2014–2024 are summarized, including new topologies, numerical-simulation methods, and application areas. The study highlights LATM capabilities in solar, wind, and bio-energy systems that require high direct torque within a small angular span. The advantages of the proposed motors – with solid and split magnetic cores – as compared to existing counterparts are described. Finite-element mathematical models have been developed and “torque-versus-angle” characteristics analyzed. The upgraded design delivers an almost constant torque over a wide angular range. The findings confirm the promise of LATMs for improving the reliability and efficiency of electromechanical drives in renewable-energy installations.  Представлено дві оригінальні конструкції електричних моментних двигунів з обмеженим кутом повороту (англ. Limited-Angle Torque Motor, LATM) зі збудженням від постійних магнітів. Узагальнено тенденції розвитку LATM за 2014–2024 рр.: нові топології, методи числового моделювання та сфери застосування. Показано можливості LATM у сонячних, вітрових і біоенергетичних установках, де потрібен великий прямий момент у малому кутовому діапазоні. Описано переваги запропонованих конструкцій двигунів (із суцільним та розділеним магнітопроводом) порівняно з існуючими аналогами. Розроблено математичні моделі (FEM-моделі) та проведено аналіз характеристик моменту від кута повороту ротора. Показано, що вдосконалена конструкція забезпечує майже постійний обертовий момент у широкому діапазоні кутів. Результати досліджень підтверджують перспективність використання LATM у системах відновлюваної енергетики для підвищення надійності та ефективності електромеханічних приводів.  Institute of Renewable Energy National Academy of Sciences of Ukraine 2025-09-28 Article Article application/pdf https://ve.org.ua/index.php/journal/article/view/545 10.36296/1819-8058.2025.3(82).19-26 Vidnovluvana energetika ; No. 3(82) (2025): Scientific and applied Journal renewable energy ; 19-26 Возобновляемая энергетика; ##issue.no## 3(82) (2025): Scientific and applied Journal renewable energy ; 19-26 Відновлювана енергетика; № 3(82) (2025): Науково-прикладний журнал Відновлювана енергетика; 19-26 2664-8172 1819-8058 10.36296/1819-8058.2025.3(82) en https://ve.org.ua/index.php/journal/article/view/545/454 Copyright (c) 2025 V. Chumak , M. Reutskyi , Yu. Haidenko , Ye. Ihnatiuk , A. Stulishenko https://creativecommons.org/licenses/by-nc-nd/4.0 |
| spellingShingle | torque motor limited-angle rotor renewable energy magnetoelectric drive LATM electromechanical actuator. Chumak , V. Reutskyi , M. Haidenko , Yu. Ihnatiuk , Ye. Stulishenko , A. PROSPECTS FOR THE USE OF LIMITED-ANGLE TORQUE MOTORS IN RENEWABLE ENERGY SYSTEMS |
| title | PROSPECTS FOR THE USE OF LIMITED-ANGLE TORQUE MOTORS IN RENEWABLE ENERGY SYSTEMS |
| title_alt | ПЕРСПЕКТИВИ ВИКОРИСТАННЯ ЕЛЕКТРИЧНИХ МОМЕНТНИХ ДВИГУНІВ З ОБМЕЖЕНИМ КУТОМ ПОВОРОТУ В СИСТЕМАХ ВІДНОВЛЮВАНОЇ ЕНЕРГЕТИКИ |
| title_full | PROSPECTS FOR THE USE OF LIMITED-ANGLE TORQUE MOTORS IN RENEWABLE ENERGY SYSTEMS |
| title_fullStr | PROSPECTS FOR THE USE OF LIMITED-ANGLE TORQUE MOTORS IN RENEWABLE ENERGY SYSTEMS |
| title_full_unstemmed | PROSPECTS FOR THE USE OF LIMITED-ANGLE TORQUE MOTORS IN RENEWABLE ENERGY SYSTEMS |
| title_short | PROSPECTS FOR THE USE OF LIMITED-ANGLE TORQUE MOTORS IN RENEWABLE ENERGY SYSTEMS |
| title_sort | prospects for the use of limited-angle torque motors in renewable energy systems |
| topic | torque motor limited-angle rotor renewable energy magnetoelectric drive LATM electromechanical actuator. |
| topic_facet | torque motor limited-angle rotor renewable energy magnetoelectric drive LATM electromechanical actuator. моментний двигун обмежений кут повороту ротора відновлювана енергетика магнітоелектричний привод LATM виконавчий електромеханізм електромеханічний актуатор. |
| url | https://ve.org.ua/index.php/journal/article/view/545 |
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