Published July 29, 2026; reviewed July 29, 2026
Estimate line voltage, phase voltage, RMS phase current, and peak phase current before you ask a supplier to wind a custom 3 phase axial flux motor.
Default screen
50kW output, 400V DC bus, 0.95 efficiency, 0.90 power factor, Wye winding.
Use the result for
Inverter current class, cable sizing conversation, and RFQ evidence requests.
The report layer does not compete with the tool. It explains how to interpret the current estimate, which evidence to ask for, and where a nominal kW match can still fail.
A 3 phase axial flux motor can look compact at the motor housing while still forcing very high RMS and peak current through the inverter, busbars, and phase cables.
Evidence:The calculator uses P = sqrt(3) x Vline,rms x Iline,rms x power factor and flags high-current cases before they become packaging or thermal problems.
For OEM procurement, the practical default is a 3-phase permanent-magnet axial flux machine driven by a BLDC/PMSM inverter. Exact winding, sensor, and control details still need supplier confirmation.
Evidence:Public axial-flux product literature is dominated by traction and industrial inverter-driven permanent-magnet machines, but public pages do not prove a universal market share.
Wye keeps phase current equal to line current and lowers phase voltage by sqrt(3). Delta keeps phase voltage equal to line voltage and lowers phase current by sqrt(3), but can raise harmonic-current risk.
Evidence:The calculator exposes Wye and Delta because the same DC bus and kW target can imply different phase-current and phase-voltage requirements.
Peak current is useful for acceleration, launch, or short bursts. Continuous operation needs coolant temperature, winding temperature limit, flow rate, and a torque-speed or efficiency map.
Evidence:The RFQ checklist separates electrical interface data from thermal validation so a peak-power claim is not mistaken for an S1 continuous rating.
The same motor housing can become a clean production drive or a current-limited prototype depending on DC bus voltage, inverter RMS current, winding connection, and cooling path.
| Assumption | Value | Use / Limit |
|---|---|---|
| Default calculation point | 50kW mechanical output, 0.95 efficiency, 0.90 power factor | Use the calculator for your actual voltage, kW target, and winding assumption. |
| Voltage model | Vline,rms ~= Vdc x 0.707 | First-pass SVPWM screening value; controller limits and modulation strategy can change available voltage. |
| Power equation | Iline,rms = Pelectrical / (sqrt(3) x Vline,rms x PF) | Mechanical output is divided by efficiency before current is estimated. |
| Procurement limit | Not a datasheet replacement | Final sizing needs Ke, Kt, phase resistance, inductance, torque-speed map, and thermal test data. |
Practical interpretation
If the result shows hundreds of amps at a low-voltage bus, do not treat the motor diameter as the only packaging constraint. The inverter, phase conductors, connector system, and coolant loop now drive the design.
These examples use the same 50kW, 0.95 efficiency, 0.90 power factor, Wye calculation point as the default tool state. They are not final motor recommendations.
| Design | Electrical Rule | Best Fit | Risk |
|---|---|---|---|
| 3-phase Wye / Star | Iphase = Iline; Vphase = Vline / sqrt(3) | Low-speed torque, compact EV traction drives, AGV and AMR wheel modules. | Can hit high phase current quickly on 48V and 96V platforms. |
| 3-phase Delta | Iphase = Iline / sqrt(3); Vphase = Vline | Higher-speed designs where voltage utilization matters more than launch torque. | Can create circulating harmonic currents if the winding and controller are not designed together. |
| Dual 3-phase | Two isolated 3-phase sets, usually driven by paired inverters | Aviation, marine propulsion, and safety-critical equipment needing redundancy. | Raises inverter count, harness complexity, calibration effort, and validation cost. |
| DC Bus | Usable Line RMS | Phase Current | Peak Current | Decision Signal |
|---|---|---|---|---|
| 48V DC | ~33.9V RMS | ~995A RMS | ~1,407A | Usually impractical for 50kW unless the package uses very large conductors and short burst duty. |
| 96V DC | ~67.9V RMS | ~497A RMS | ~703A | Possible for short bursts, but inverter and connector thermal limits dominate the design. |
| 400V DC | ~282.8V RMS | ~119A RMS | ~169A | A more realistic traction-voltage screening point for light EV and industrial packages. |
| 800V DC | ~565.7V RMS | ~60A RMS | ~84A | Current is cleaner, but insulation, safety, and inverter cost move up. |
AFPM Motor 3-phase calculator model
Updated July 29, 2026
Uses Vline,rms ~= Vdc x 0.707 under a first-pass SVPWM assumption, then estimates line RMS current from three-phase real power.
Confidence:High for arithmetic screening; medium for hardware until verified with motor constants, inverter limits, and dyno data.
Open calculatorYASA P400-R public product page
Reviewed July 29, 2026
A production-oriented axial-flux benchmark should be read as a specific motor/inverter package, not as a generic rule for every 3 phase axial flux motor.
Confidence:High for the existence of the published product page; medium when extrapolated to custom procurement.
YASA product pageImperix SVPWM technical note
Reviewed July 29, 2026
Space-vector PWM changes voltage utilization compared with sinusoidal PWM, so DC bus voltage and modulation method must be stated in the inverter match.
Confidence:Medium-high for modulation context; final value depends on controller implementation and limits.
SVPWM noteAstrodyne TDI, 3-phase Delta vs Wye overview
Reviewed July 29, 2026
Wye and Delta connections use different line-to-phase voltage/current relationships, which changes phase-current interpretation.
Confidence:Medium for fundamentals summary; supplier winding drawings remain the procurement source of truth.
Y/Delta referenceAFPM Motor inquiry workflow
Updated July 29, 2026
RFQ review should request DC bus range, inverter RMS/peak current, winding connection, torque-speed map, and cooling data in one package.
Confidence:High for internal review process; final design remains application-specific.
RFQ checklistTreat these risks as review gates. A supplier quote that does not resolve them is not ready for prototype approval.
Trigger:Specifying a “3 phase axial flux motor” but expecting it to run directly from wall AC.
Mitigation:Use a VFD or BLDC/PMSM inverter that synthesizes the motor-side three-phase waveform.
Trigger:Peak or RMS current exceeds module, capacitor, connector, or cooling limits.
Mitigation:Raise DC bus voltage, reduce peak torque, change winding turns, or select a higher-current inverter.
Trigger:Short burst power is treated as continuous S1 output.
Mitigation:Ask for coolant conditions, winding temperature rise, duty cycle, and dyno evidence.
Trigger:Supplier and buyer quote “phase current” while using different winding definitions.
Mitigation:Require winding diagram, line current, phase current, phase voltage, and controller RMS/peak definitions.
| Platform | Typical DC Bus | Decision Focus |
|---|---|---|
| AGV / AMR drive module | 48-96V | Check current first. Low-voltage systems often hit connector and busbar limits before motor packaging limits. |
| Light EV / motorcycle | 96-400V | Match peak launch torque to inverter current, then verify cooling for hill climbs and repeated acceleration. |
| Drone / eVTOL auxiliary drive | 400-800V | Prioritize mass, redundancy, insulation clearance, bearing load, and fault handling over raw kW density. |
| Industrial pump or fan | 400-800V | Treat continuous duty, thermal stability, ingress protection, and service life as the primary gate. |
Send the calculator result with these evidence requests so the supplier answers electrical, thermal, and mechanical fit in the same review cycle.
| Data Area | Ask The Supplier For | Decision It Supports |
|---|---|---|
| Inverter interface | DC bus range, line RMS current, peak phase current, switching frequency, sensor type, and field-weakening limit. | Confirms whether the controller can actually deliver the torque-speed target. |
| Motor constants | Kt, Ke, phase resistance, phase inductance, pole count, winding connection, and temperature basis. | Prevents generic kW comparisons from hiding voltage and current incompatibility. |
| Thermal evidence | Coolant type, flow rate, inlet temperature, winding limit, thermal sensor location, and derating curve. | Separates peak launch power from continuous production duty. |
| Mechanical package | Outer diameter, axial length, mass, shaft/bearing loads, mounting face, IP rating, and resolver or encoder package. | Validates the axial-flux packaging advantage against real integration constraints. |
| Validation data | Torque-speed map, efficiency map, NVH notes, insulation class, hipot result, and thermal-cycle report. | Gives procurement enough evidence to move from calculator screening to prototype approval. |
The motor-side waveform is three-phase AC generated by an inverter. The system may be fed by a DC battery or DC link, but the inverter still controls phase current and frequency.
No. A single-phase supply must feed a VFD or BLDC/PMSM inverter that creates the motor-side three-phase output.
For the same mechanical output, a higher usable line RMS voltage lowers the line RMS current required by the three-phase power equation.
No. Battery or DC-link current is an input-side value. Motor phase RMS current depends on modulation, winding connection, motor constants, and operating point.
Choose Wye when launch torque and lower-speed control dominate. Choose Delta only when the motor and controller are designed for higher-speed operation and harmonic-current risk is addressed.
The inverter will current-limit, thermally derate, fault, or fail depending on protection design. The motor will not reach its advertised peak torque.
It lowers current for the same power, but it raises insulation, safety, connector, and inverter cost requirements.
The real power delivered by a three-phase machine depends on voltage, current, and power factor. Using a realistic PF avoids underestimating current.
Request DC bus range, inverter RMS and peak current, winding connection, Kt, Ke, phase resistance, cooling conditions, torque-speed map, and efficiency map.
No. Compare mass only after rating basis, cooling hardware, duty cycle, controller mass, and test temperature are stated.
Use it as a screening result to decide whether the voltage/current target is plausible, then ask the supplier for measured data at your exact operating point.
Missing thermal data, undefined current basis, no winding diagram, no inverter derating curve, or no torque-speed map should stop production approval.
Include your DC bus voltage, target kW, duty cycle, winding assumption, allowable phase current, cooling method, and package envelope. The engineering team can then respond with a winding and inverter review instead of a generic brochure.
Inquiry Email
Please include application, peak/continuous torque, speed range, voltage/current limit, outer diameter, axial length, cooling method, quantity, and drawings or reference samples.
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+86 188 5797 1991
Share torque-speed, package, cooling, and sample quantity in the first message.
Axial Flux PM Motor
Review the permanent-magnet topology and RFQ scope.
Motorcycle & Light EV Drives
Map motor voltage, torque, and cooling choices to light EV use.
Drone & eVTOL Propulsion
Compare mass, redundancy, and high-voltage integration tradeoffs.
AFPM Quality Validation
See the validation evidence to request before prototype approval.
