1. Variable Reluctance Resolver Features：

With a simple structure and no coupling transformer, it is brushless, highly accurate, low-cost, and has low environmental requirements.  It facilitates the integration of the transmission system and utilizes the rotor salient pole effect to induce sine and cosine signals related to the rotation angle in the stator windings, achieving non-contact, highly reliable angular position detection. It is widely used in electric vehicles, servo control, and other fields, and can replace traditional rotary transformers.  Applications include automotive electronic power steering (EPS), mining machinery (underground coal trucks, conveyor belt motors, etc.), and high-speed trains.

2. Core advantages

• Simple and reliable structure: Both the excitation winding and output winding are fixed on the stator, and the rotor has no windings, brushes, or slip rings, achieving completely contactless operation and improving reliability.

• High precision: The signal is generated by the change in air gap permeability caused by the salient pole effect of the rotor, resulting in extremely high precision, reaching the "second" level.

• Low cost: The simplified structure reduces material and processing costs.

• Easy integration: Small size and light weight make it easy to integrate with motor drive systems.

• Strong anti-interference ability: The brushless structure requires less demanding environmental conditions and has good anti-interference capabilities.

3. Why did the resolver control unit report an error during the first test?

Are the frequency, input voltage, turns ratio, and current loss of the resolver consistent with the values set by the control unit。Stranded cable (input voltage, Sin, Cos)

Is there any electromagnetic interference (from motor brakes, excessively long cables)

4. Why can resolver products in the same series have different specifications?

Because servo controllers commonly found on the market come in different frequencies and voltages. The data on resistance and phase shift in the three tables correspond to various resistances, impedance strengths, and phase shifts under two to three different input frequencies and feedback voltages. We provide you with the necessary information to help you select the correct analog-to-digital converter or appropriate control components.

5. How to install and secure the stator and rotor of a rotary transformer?

The stator is mounted to the bearing housing of the motor. It is secured using clamps or snap rings.

The rotor is typically glued to the rotating shaft. For some special shapes or security applications, the rotor can be secured to the shaft using axial screws. For larger shaft diameters, the rotor is secured with radial clamping screws (e.g., set screws).

6. What is the accuracy of the resolver?

Standard resolvers have an absolute measurement accuracy of ±10'. In most cases, this accuracy is sufficient for speed control units with typical systems. For applications requiring higher precision positioning, we also offer resolvers with absolute measurement accuracies of ±6' and ±4'.

Live Applications of Variable Reluctance (VR) Rotary Transformers

A reluctance-type resolv­er rotor has no windings or brushes, with all the windings arranged on the stator. It's sturdy and can handle high temperatures, strong vibrations, oil, dust, and heavy electromagnetic interference. It outputs sine and cosine angle signals based on changes in magnetic reluctance, and when paired with an RDC decoding chip, you can get the rotor's angle and speed. It's widely used for position feedback in permanent magnet synchronous motors under harsh conditions.

• New energy vehicles (largest mass production application scenario)

1. Main drive motor (BEV/PHEV)

2. EPS electric power steering motor

3. ISG hybrid start-generator, electronic brake booster motor EBB, air compressor motor

• Industrial Automation and Servo Equipment

1. High-power servo motor, explosion-proof servo motor：In metallurgy, injection molding, textiles, and coal mine explosion-proof equipment, the glass discs of photoelectric encoders are easily damaged by oily mist and dust; magnetoresistive resolvers have no optical components and can operate maintenance-free for a long time.

2. Industrial robot joint servos, collaborative robots：Frequent repeated impacts on the joint and tight spaces call for a thin magnetic reluctance resolver; using a multi-speed magnetic reluctance resolver improves angular accuracy.

3. High-speed CNC machine spindle：High-speed spindle, oil-cooled environment, position and speed feedback.

4. Wind turbine pitch servo：The wind turbine nacelle experiences large day-night temperature differences and heavy vibrations, the pitch motor rotor position feedback is needed, and it's outdoors without anyone on-site for a long time.

• rail transit field

High-speed train and urban rail traction permanent magnet motors; locomotive auxiliary motors.

Operating conditions: -40 to 125°C, vehicle body shock and vibration, strong electromagnetic noise from high-power converters; installed at the traction motor end to detect rotor position for vector control, with some models domestically replacing imported wound resolvers.

• Aerospace and Special Military Applications

Meets DO-160 and GJB military standards, resistant to high and low temperatures, shocks, radiation, and vacuum degassing.

1. Aircraft engine FADEC control systems, helicopter actuators: high-temperature engine areas, servo motor position feedback.

2. Spacecraft attitude control actuators, onboard servos.

3. Downhole oil and gas equipment, underwater marine actuators: high temperature and high pressure downhole, electronic components cannot be placed on the rotor side, reluctance resolver rotors made entirely of silicon steel laminations, extremely reliable.

• Other niche real-world scenarios

- Energy storage flywheel motors: high-speed rotation, vacuum environment;

- Electrification of construction machinery and heavy trucks: hydraulic pump-driven motors;

- Auxiliary motors for electric ship propulsion.