Wound Rotor Synchronous Motors (WRSM)

Name: Wound Rotor Synchronous Motors (WRSM)
Brand: Magnet-Free Motor
Availability: PreOrder

High power-density externally excited synchronous motor programs for EV traction and e-axle teams eliminating NdFeB supply-chain risk while retaining controllable rotor flux.

Target Buyer:Best for OEM EV engineering, Tier-1 drivetrain, and advanced mobility teams migrating away from PMSM platforms while keeping high-speed efficiency and supply-chain control.

Engineering Assets

Request reference specifications and STEP models without a registration gate. We confirm the correct package after a quick project-fit check.

Request Datasheet Request STEP Model

Wound rotor motor assembly with visible slip ring interface for excitation programs

Capability Highlights

Zero permanent magnet cost volatility for rare-earth-risk reduction
Controllable rotor field for high-speed flux weakening strategies
Slip ring, brush, or brushless excitation interface manufacturing review
Hairpin stator, wound rotor, insulation, impregnation, and balance support
Prototype-to-pilot manufacturing path for EV and heavy mobility programs
Manufacturing evidence for resistance, hipot, VPI, balance, and dyno checks

Typical Applications

EV traction motors
E-axle drive units
Hybrid and heavy-duty mobility traction
Aerospace electrification prototypes
Rare-earth-free drivetrain R&D platforms

Engineering Focus

Rotor winding slot fill factor, retention, and centrifugal load margin
Class F/H insulation, VPI impregnation, and thermal path validation
High-speed balancing, overspeed margin, and shaft interface tolerance
Excitation current, voltage window, brush/slip-ring wear assumptions, or brushless coupler constraints
Torque-speed map, inverter control strategy, cooling circuit, and dyno acceptance points

Key Evaluation Matrix

Metric	Typical Range	Why It Matters
Power Density	>= 1.6 kW/kg target review	Critical for EV weight reduction and range extension.
Excitation Interface	Slip ring / brush / brushless review	Defines rotor package, reliability risks, electrical interface, and test scope.
Insulation Class	Class F / H project dependent	Rotor thermal durability is one of the main adoption gates for EESM traction.
Validation Evidence	Resistance, hipot, VPI, balance, dyno	Procurement teams need measurable sample evidence before design freeze.
Cooling Strategy	Water jacket / oil / hybrid review	Cooling assumptions determine winding temperature, power density, and package feasibility.

Production and Validation Flow

Process Step	Buyer Evidence	Acceptance Gate
Architecture and excitation review	Torque-speed map, field-current window, inverter limits, excitation interface, cooling assumptions, and package constraints.	WRSM/EESM scope is separated into stator, rotor, excitation interface, or complete motor support.
Rotor/stator DFM and validation plan	Winding route, hairpin stator notes, rotor retention method, insulation class, VPI route, and dyno-point plan.	Critical manufacturing and test risks are agreed before prototype build.
Prototype build and sample evidence	Resistance, hipot, IR/surge, VPI, balance, dimensional inspection, thermal, and dyno records.	Buyer can approve iteration, pilot release, or architecture stop using measurable records.
Pilot transition and change control	Drawing revision baseline, control plan, lot traceability, packaging, lead time, and deviation process.	Program is ready for controlled pilot lots with stable acceptance criteria.

RFQ Checklist

Torque-speed curve, peak/continuous power, base speed, and maximum speed
Excitation architecture preference and field current/voltage window
Cooling method, thermal limits, duty cycle, and ambient assumptions
Rotor/stator drawings, stack length, airgap, shaft interface, and housing constraints
Insulation class, partial discharge target, balance grade, and overspeed requirement
Prototype quantity, validation plan, annual forecast, and target delivery country

Risk Controls

Rotor thermal failure: Rigorous dynamometer thermal mapping and Class H insulation.
Excitation interface wear or packaging conflict: Review brush, slip-ring, or brushless excitation architecture together with duty cycle and service targets.
High-speed rotor imbalance: Freeze balance grade, overspeed speed, correction method, and report format before pilot samples.
Late inverter-control changes: Align field weakening, current limits, resolver/encoder needs, and dyno points before sample order.

Product Gallery

Wound rotor synchronous motor sample for EESM and WRSM validation

Hairpin stator winding used in rare-earth-free EV traction motor manufacturing

Buyer FAQ

Can you handle high-speed balancing?

Yes, we provide dynamic balancing test reports for every rotor assembly.

Can you build only the stator or rotor instead of a complete motor?

Yes. Many projects start with hairpin stator, wound rotor, lamination stack, or excitation-interface components before full motor integration.

What drawings are required for first review?

Send rotor/stator drawings, shaft interface, stack geometry, cooling assumptions, excitation window, target speed, and validation requirements.

Related Resources

Inquiry Email

[email protected]

Email app

Include target torque/speed, quantity, and delivery location.

Instant Chat

+86 18857971991

Chat on WhatsApp

Direct response from our engineering team.

Wound Rotor Synchronous Motors (WRSM)

High power-density externally excited synchronous motor programs for EV traction and e-axle teams eliminating NdFeB supply-chain risk while retaining controllable rotor flux.

Target Buyer:Best for OEM EV engineering, Tier-1 drivetrain, and advanced mobility teams migrating away from PMSM platforms while keeping high-speed efficiency and supply-chain control.

Capability Highlights

Zero permanent magnet cost volatility for rare-earth-risk reduction

Controllable rotor field for high-speed flux weakening strategies

Slip ring, brush, or brushless excitation interface manufacturing review

Hairpin stator, wound rotor, insulation, impregnation, and balance support

Prototype-to-pilot manufacturing path for EV and heavy mobility programs

Manufacturing evidence for resistance, hipot, VPI, balance, and dyno checks

Engineering Focus

Rotor winding slot fill factor, retention, and centrifugal load margin

Class F/H insulation, VPI impregnation, and thermal path validation

High-speed balancing, overspeed margin, and shaft interface tolerance

Excitation current, voltage window, brush/slip-ring wear assumptions, or brushless coupler constraints

Torque-speed map, inverter control strategy, cooling circuit, and dyno acceptance points

Key Evaluation Matrix

Metric	Typical Range	Why It Matters
Power Density	>= 1.6 kW/kg target review	Critical for EV weight reduction and range extension.
Excitation Interface	Slip ring / brush / brushless review	Defines rotor package, reliability risks, electrical interface, and test scope.
Insulation Class	Class F / H project dependent	Rotor thermal durability is one of the main adoption gates for EESM traction.
Validation Evidence	Resistance, hipot, VPI, balance, dyno	Procurement teams need measurable sample evidence before design freeze.
Cooling Strategy	Water jacket / oil / hybrid review	Cooling assumptions determine winding temperature, power density, and package feasibility.

Production and Validation Flow

Process Step	Buyer Evidence	Acceptance Gate
Architecture and excitation review	Torque-speed map, field-current window, inverter limits, excitation interface, cooling assumptions, and package constraints.	WRSM/EESM scope is separated into stator, rotor, excitation interface, or complete motor support.
Rotor/stator DFM and validation plan	Winding route, hairpin stator notes, rotor retention method, insulation class, VPI route, and dyno-point plan.	Critical manufacturing and test risks are agreed before prototype build.
Prototype build and sample evidence	Resistance, hipot, IR/surge, VPI, balance, dimensional inspection, thermal, and dyno records.	Buyer can approve iteration, pilot release, or architecture stop using measurable records.
Pilot transition and change control	Drawing revision baseline, control plan, lot traceability, packaging, lead time, and deviation process.	Program is ready for controlled pilot lots with stable acceptance criteria.

RFQ Checklist

Torque-speed curve, peak/continuous power, base speed, and maximum speed

Excitation architecture preference and field current/voltage window

Cooling method, thermal limits, duty cycle, and ambient assumptions

Rotor/stator drawings, stack length, airgap, shaft interface, and housing constraints

Insulation class, partial discharge target, balance grade, and overspeed requirement

Prototype quantity, validation plan, annual forecast, and target delivery country

Risk Controls

Rotor thermal failure: Rigorous dynamometer thermal mapping and Class H insulation.

Excitation interface wear or packaging conflict: Review brush, slip-ring, or brushless excitation architecture together with duty cycle and service targets.

High-speed rotor imbalance: Freeze balance grade, overspeed speed, correction method, and report format before pilot samples.

Late inverter-control changes: Align field weakening, current limits, resolver/encoder needs, and dyno points before sample order.