High-Performance AC Servo Motors: Precision and Power in Motion Control

In the realm of motion control, Ac Servo Motors stand out for their exceptional performance, responsiveness, and reliability. For applications demanding precise movements and high power within a compact footprint, Hudson servo motors are engineered to deliver. This article delves into the key features that make Hudson AC servo motors a superior choice for demanding applications.

Unmatched Power Density in AC Servo Motors

Achieving peak performance requires a harmonious blend of high peak torque, continuous torque, and rated speed. Hudson AC servo motors are meticulously designed to excel in all three aspects:

High Peak Torque: Utilizing sintered Neodymium-Iron-Boron magnets, far superior to plastic-bonded alternatives, Hudson AC servo motors maximize peak torque. Advanced 3-D Finite Element Analysis (FEA) software is employed to fine-tune magnet shapes, optimize winding fill factor, stator skew angle, and rotor geometry. This sophisticated design ensures maximum power output when you need it most.
High Continuous Torque: Efficient heat management is crucial for sustaining high continuous torque. Hudson AC servo motors feature an optimized thermal design that facilitates effortless heat dissipation. Even under heavy loads, the 200ºC-rated winding insulation maintains operational safety, and the specially formulated permanent magnets resist field strength degradation, ensuring consistent performance over prolonged use.
High-Speed Operation: Demanding applications often require AC servo motors to operate at high speeds while maintaining precise control. Hudson AC servo motors are engineered with a fast electrical time constant—a low ratio of winding inductance to resistance. This minimizes impedance to high-frequency current variations, effectively eliminating torque droop and ensuring optimal performance even at elevated speeds. The combination of high-speed capability and sustained high torque translates directly into maximum power for your application.

Alt text: Comparison of sintered NdFeB magnets versus plastic bonded Neodymium magnets in AC servo motor rotors, highlighting sintered magnets’ superior power density for compact servo motor design.

Responsive AC Servo Motors for Dynamic Control

For high-performance servo control, characterized by dynamic accuracy, precise velocity regulation, and rapid settling times, responsiveness is paramount. AC servo motors must be responsive both electromagnetically and mechanically. Hudson AC servo motors are engineered for exceptional responsiveness:

Fast Electrical Time Constant: Beyond minimizing steady-state torque droop, the fast electrical time constant of Hudson AC servo motors enables rapid response to transient demands from high-performance servo drives. This ensures that the motor reacts instantaneously to changes in command, maintaining precise control even in highly dynamic applications.
Quick Mechanical Response: Achieving rapid mechanical response necessitates generating high peak torque with a low inertia rotor. Hudson AC servo motors are designed with a high torque-to-inertia ratio. This means less torque is wasted on accelerating the rotor itself, and more torque is readily available to accelerate the load. The result is faster acceleration, deceleration, and overall system responsiveness.

Alt text: Advanced stator winding of an AC servo motor, showcasing a tightly packed, high fill factor design for enhanced power and responsiveness.

Smooth and Quiet Operation – Hallmarks of Hudson AC Servo Motors

While some AC servo motors achieve high torque at the expense of smooth operation, Hudson AC servo motors prioritize both. Many high-torque servo motors suffer from high detent torque, leading to jerky motion and unwanted vibrations. They may also exhibit back-EMF distortion, causing torque ripple even with sophisticated AC sinewave servo drives. These imperfections degrade settling time, induce servo hunting, and generate noise and vibration. Smooth, quiet motion requires an AC servo motor with minimal detent torque and linear, low-ripple torque output. Rotor balance and bearing quality are equally critical, especially at higher speeds.

Magnetic design plays a significant role in brushless motor noise and vibration. Internal Permanent Magnet (IPM) rotor designs, while sometimes used to reduce costs, can compromise servo performance. IPM designs can lead to inductance variations during rotation, resulting in inferior servo control and pulsating forces that generate audible noise and vibration.

External Permanent Magnet (EPM) Rotor Design: Hudson AC servo motors employ an External Permanent Magnet (EPM) rotor design. This design is chosen specifically for maximum smoothness and minimal audible noise. The EPM design avoids the inherent noise and performance drawbacks of IPM designs, ensuring superior motion quality.
Minimized Detent Torque and Torque Ripple: Hudson AC servo motors incorporate obliquely aligned stator lamination teeth and precisely shaped permanent magnets to minimize detent torque. Furthermore, they produce a harmonically pure back-EMF, effectively minimizing torque ripple. These design features contribute significantly to smoother, quieter operation.
Precision Balancing and High-Quality Bearings: Every Hudson BLDC motor undergoes precise custom rotor balancing and is equipped with high-quality bearings. This combination guarantees ultra-smooth mechanical movement, minimizing vibration and noise, especially crucial for sensitive applications.
A Step Up from Stepper Motors: For designers accustomed to stepper motors, the smooth and quiet motion of Hudson AC servo motors will be particularly noticeable. The transition to servo technology offers a significant upgrade in motion quality and precision.

Alt text: Audible noise comparison graph of AC servo motors with Internal Permanent Magnet (IPM) versus External Permanent Magnet (EPM) rotor designs, demonstrating the quieter operation of EPM servo motors, especially in the human-sensitive 400 Hz to 5 kHz range.

Versatile AC Servo Motors for Diverse Applications

The exceptional power density of Hudson AC servo motors enables them to fit into space-constrained applications where other brushless motors may not. Their open-standard design ensures compatibility with a wide array of servo drives.

High Motor Constant (Km): Hudson AC servo motors boast a very high motor constant (Km) per unit volume. This translates to maximum power output for a given motor size, making them ideal for applications where space is at a premium.
Space-Saving Cable Routing: Select Hudson AC servo motor models feature a single cable, single connector pigtail that exits tangentially from a recessed groove. This innovative design minimizes the space required for cable routing and service loops, further enhancing the motor’s effective power-to-size ratio.
Open-Standard Feedback: Hudson AC servo motors utilize standard quadrature encoder feedback and 120-degree commutation sensors. This adherence to industry standards ensures compatibility with virtually every make and model of brushless servo drive, eliminating vendor lock-in and providing design flexibility.
Brushless Design Advantages: The brushless design of Hudson AC servo motors eliminates the arcing, electrical noise, and carbon dust associated with brush-type motors. This makes them particularly well-suited for noise-sensitive and dust-sensitive environments, such as cleanrooms, medical devices, and laboratory equipment.

Alt text: Space-saving rotary optical encoders integrated with AC servo motors, illustrating the compact feedback solutions available for precision motion control.

Alt text: Connector and wiring harness options for AC servo motors, highlighting the space-efficient tangential-exit pigtail design for streamlined integration.

Rugged and Reliable AC Servo Motors: Built to Last

Hudson AC servo motors are engineered for rugged reliability, minimizing downtime and ensuring long-term performance in demanding industrial environments. Brushless servo motors inherently offer greater reliability than brush-type motors due to the absence of brushes, efficient heat dissipation, and minimal moving parts. Hudson takes reliability a step further with specific design features:

Oversized Precision Bearings: Hudson AC servo motors utilize oversized, precision bearings. These bearings are designed to minimize wear and prevent premature failure, especially in applications with radial (side) loading. They are permanently sealed with high-performance grease, reducing friction, minimizing motor noise, and eliminating the need for bearing maintenance.
Robust Stator Windings: In all brushless motor stators, the end windings are more vulnerable to overheating. Hudson AC servo motors feature machine-formed, densely packed end-turns. This unique construction creates a single thermal mass, protecting against spot overheating and burn-out, enhancing overall winding durability.
Corrosion-Resistant Magnets: The neodymium-rich permanent magnets in Hudson AC servo motors are protected with a thick nickel plating. This plating provides exceptional resistance to corrosion and hydrogen absorption, preventing brittleness and decrepitation (crumbling) common in rare-earth magnets, ensuring long-term magnet integrity.
Reliable Encoder Mounting: The encoder disk is securely attached to the shaft using an expanding mandrel-type clamp, eliminating set-screw failures prevalent in many encoders. This symmetric clamping method also reduces run-out error and improves rotor balance, contributing to both reliability and precision.
Integrated Thermal Protection: A built-in thermal sensor safeguards the AC servo motor by alerting the servo drive when the encoder electronics reach their maximum safe operating temperature. This prevents thermal damage and ensures that the motor windings operate well below their 200ºC rating, providing a substantial safety margin against overheating and insulation failure.
Noise-Immune Encoder: The fully integrated optical encoder boasts exceptional noise rejection thanks to redundant optical apertures, internal power supply filtering, and feedback-controlled illumination. Its shatter-proof, stainless steel encoder disk further enhances reliability. The encoder’s low current draw (40mA) also reduces heat generation and load on the motor drive, contributing to overall system efficiency and longevity.
Efficient Heat Dissipation Housing: Hudson AC servo motors feature an all-aluminum housing compression-fit to the stator, significantly improving conductive heat transfer to the mounting flange, the primary heat sink. The grooved housing further enhances convective heat transfer. These features combine to keep the motor cooler, extending its lifespan and boosting reliability.
Durable Anodized Finish: The AC servo motor housing is finished with a UV- and heat-resistant, “architectural quality” anodized coating. This robust finish is scratch-resistant, prevents peeling or flaking, and maintains the housing’s metallic appearance, ensuring long-lasting aesthetics and protection.
UL and CE Certification: The entire Hudson AC servo motor family has undergone rigorous testing and achieved UL and CE certification. These certifications validate that Hudson servo motors meet stringent standards for electrical safety and electromagnetic emissions, providing independent assurance of product quality and safety.

Alt text: Tightly packed and laced stator windings in an AC servo motor, designed to act as a single thermal mass for improved heat dissipation and hotspot reduction, enhancing servo motor reliability.

Alt text: Comparison of AC servo motor body surface coatings: a hard anodized finish versus painted or epoxy coatings, highlighting the superior durability and chip-resistance of anodized finishes for long-term reliability.

Alt text: Three-year warranty badge for AC servo motors, signifying exceptional product reliability and manufacturer confidence in long-term performance.

Reliability Through Rigorous Testing

Every Hudson AC servo motor undergoes a comprehensive suite of in-line and post-production tests to guarantee exceptional incoming quality. These tests encompass:

Electromagnetic performance verification
Magnet field strength measurement
Encoder integrity assessment
Rotor balance validation
Commutation sensor accuracy testing
Critical mechanical tolerance checks
Insulation system (hipot) testing
Complete functional performance evaluation
HASS (Highly Accelerated Stress Screening) testing beyond published specifications

Unmatched Warranty for AC Servo Motors

Hudson AC servo motors are backed by an industry-leading three-year warranty. Teknic extends this commitment further by deferring the warranty start date until the motor is put into service (up to six months after purchase), acknowledging potential storage periods. This unparalleled warranty demonstrates Teknic’s confidence in the long-term reliability of Hudson AC servo motors.

Cost Savings Across the Board with Hudson AC Servo Motors

The total cost of ownership extends beyond the initial purchase price. It encompasses peripheral components, installation, engineering, and long-term maintenance. Hudson AC servo motors excel in minimizing costs across all these areas.

Competitive Purchase Price

Hudson AC servo motors are offered at a highly competitive purchase price. This is achieved through:

OEM-Focused Direct Sales: Teknic’s OEM focus eliminates distributor markups, allowing direct purchasing at 100-piece annual quantity pricing even for individual servo motors. Direct factory technical support further enhances value.
Intelligent Option Limitation: By strategically limiting the number of options, manufacturing complexity and expenses are drastically reduced. These savings are passed on to customers in the form of lower prices without compromising performance or quality. The available options still provide ample flexibility for most applications, including winding choices, connector types, encoder outputs, resolutions, and IP66K/IP67 sealing. NEMA 23 size servo motors also offer shaft diameter options.

Whether seeking a superior, lower-cost AC servo motor or an economical, high-performance stepper motor replacement, Hudson AC servo motors are designed to meet diverse needs.

Installation Cost Savings

Thoughtful design features in Hudson AC servo motors translate into installation cost savings:

Finished Pigtails/On-Body Connectors: Pre-terminated pigtails or on-body connectors eliminate the labor and potential wiring errors associated with “flying leads,” simplifying installation and saving time.
Single-Connector Extension Cables: For models with pigtails, the single-connector design for extension cables significantly reduces costs compared to multi-connector systems.
Robust Standard Encoder Outputs: Hudson’s standard configuration includes encoders with high-current, low-impedance, totem-pole outputs. This robust interface minimizes noise issues common with open-collector encoder outputs and uses fewer wires than differential encoders, saving cable costs and space. A differential encoder option is available for demanding applications with long cable runs or severe electrical noise.

Alt text: Versatile cable orientation options with Hudson AC servo motors using Souriau Trim Trio connectors, demonstrating space-saving and flexible wiring configurations.

Alt text: AC servo motor wiring harness options: sealed IP65 Souriau Trim Trio connector and flying leads, showcasing the convenience of pre-terminated connectors and elimination of flying leads for simplified installation.

Assured Application Success with Expert Support

Teknic’s OEM-centric approach ensures application success through expert support. Factory specialists offer free solid-body simulations of your application to optimize AC servo motor selection, ensuring the right motor size for your specific needs. Custom torque/speed curves tailored to your chosen motor drive (including compatibility with virtually any brushless servo drive, and optimized for Teknic servo drives) are also provided, guaranteeing confident system performance.

Considering an all-in-one solution? Explore ClearPath – Teknic’s line of brushless servo motors with integrated drive and controller, offering simplicity, compactness, and cost-effectiveness.

Alt text: Torque-speed curve graph for a Teknic Hudson AC servo motor, illustrating performance characteristics and application suitability, and highlighting Teknic’s OEM application simulation services.

Understanding AC Servo Motor Terminology

The terminology surrounding brushless motors can be confusing. Hudson motors are accurately described as:

BLDC motor, brushless dc electric motor
Three-phase, permanent magnet motor
Synchronous, permanent magnet motor
AC servo motor (due to sinusoidal current for electronic commutation, distinct from AC induction motors)
DC servomotor (distinguishing from AC induction motors)
3-phase servomotor or simply servo motor

Technically, Teknic’s servo motors are “3-phase, synchronous, permanent magnet, brushless, servo motors.” “Servomotor” implies feedback control (e.g., encoder) for torque, velocity, and/or position. “Brushless” indicates electronic commutation. “Permanent magnet” denotes rotor magnets. “Synchronous” means rotor and electromagnetic field speeds are synchronized. “3-phase” refers to three stator windings.

Stepper motors, also brushless and permanent magnet, are typically 2-phase or 5-phase and usually open-loop controlled, unlike AC servo motors which are closed-loop for precise control. Stepper motors are commutated in steps, with the rotor following incrementally. AC servo motors offer superior precision and control compared to stepper motors in demanding applications.