4
Source-backed boundaries
Safety, FOC sensing limits, and I2t limits are separated from supplier-specific claims.
Hybrid Tool & Engineering Report
100A PMSM Servo Drive Calculator
Compare your PMSM phase current with a 100A reference, then identify the rating, thermal, and FOC evidence required before locking the robot actuator design.
Published September 24, 2026; evidence and assumptions reviewed October 3, 2026. The calculator is a screening tool; final release still requires supplier derating data and thermal validation.
100A PMSM Servo Drive Sizing Calculator
Compare continuous and peak phase RMS current with a 100A numeric reference. Pulse duration and cooling are recorded as review context; this tool does not predict thermal capability or final drive fit.
Enter a positive phase RMS current (Arms). Confirm the supplier rating uses the same phase and RMS basis.
Enter RMS phase current during the high-load interval. If the datasheet gives Apk or bus current, confirm its definition before comparing.
Enter a positive pulse duration. Repetition rate and the vendor protection curve are also needed to assess thermal limits.
Context only. The choice does not change the numeric result; confirm the vendor’s tested cooling condition.
Ready to Compare Current
Enter the duty-cycle values to run the current-only screen.The first result compares the entered phase RMS currents with a nominal 100A reference. It does not predict drive fit.Next step: Fill all fields, then click Compare Current Envelope.
Continuous current vs referenceAwaiting input
Enter continuous phase current in Arms
Peak current vs referenceAwaiting input
Enter peak phase current in Arms
Assumptions shown in result
- - Enter motor phase RMS current values (Arms) from the datasheet or measured duty.
- - Treat the 100A value as a numeric reference until the supplier rating basis is confirmed.
- - Cooling and pulse duration are context for the supplier review, not a thermal model.
3
Scenario screens
Calculator examples cover compact robotics, mobile automation, and direct-drive high-torque axes.
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Supplier checks
The RFQ list forces continuous, pulse, cooling, motor-control, and FOC loop evidence into one review.
Decision Summary
Key Takeaways for 100A Drive Selection
4x
Thermal load & I²t
At the same phase-path resistance, 100A produces four times the instantaneous I²R loss of 50A. That ratio alone does not determine a drive or motor thermal limit; duty cycle, cooling, and the supplier protection model still matter.
Noise
Sensing trade-off
For illustration, mapping a 200A span onto an ideal 12-bit ADC gives about 0.049A per code. Real current resolution also depends on sensor gain, offset, noise, filtering, and sampling; this arithmetic does not predict torque ripple.
Peak?
Rating ambiguity
A compact drive advertised as 100A may mean 100A peak, not 100A continuous. Ask for continuous current, peak duration, repetition rate, and cooling condition together to calculate the true RMS limit.
How the Tool Decides
The calculator compares entered phase RMS current with a nominal 100A reference. It does not infer pulse capability from duration or cooling because suppliers define current ratings and thermal protection for specific products and test conditions.
| Input | Why it matters | Screening rule |
|---|---|---|
| Continuous current | Provides one current magnitude to compare with a supplier continuous phase-current rating on the same basis. | This page compares against a nominal 100A phase-RMS reference only; it does not apply a cooling derating factor. |
| Peak current | Shows peak current magnitude relative to the same nominal reference. | Values above 100A are outside this numeric screen. Supplier limits may use a different phase, RMS, or peak convention. |
| Peak duration | Suppliers need pulse width and repetition rate to specify transient current capability. | Recorded for review only; no universal duration threshold or thermal model is applied. |
| Cooling condition | The supplier rating depends on the tested mounting and cooling condition. | Context only. Compare with the exact cooling condition used in the supplier rating. |
Evidence Layer
Sources, Scope, and Known Limits
The page separates general engineering rules from vendor-specific ratings. Public sources support the safety and technology framing; supplier datasheets must still confirm the exact 100A current envelope for a purchase decision.
Review cycle: refreshed every six months, or sooner when supplier ratings, safety standards, or GaN motor-drive guidance change.
| Source | Supports | Boundary | Date note |
|---|---|---|---|
| IEC 61800-5-1 adjustable speed electrical power drive safety standard | The standard covers electrical, thermal, fire, mechanical, energy, and other hazards for power drive systems. | Use the standard to frame safety review; it does not publish a vendor-specific current rating. | IEC source reviewed October 3, 2026 |
| Texas Instruments GaN technology and motor-drive guidance | TI says GaN devices can switch faster and have the potential to reduce switching loss; its page lists motor drives among possible applications. | The source describes device-level potential, not a guaranteed PMSM drive efficiency, current rating, or switching-frequency target. | TI source reviewed October 3, 2026 |
| Texas Instruments, Low-Drift In-Line Motor Current Measurements | Motor phase current measurement depends on sensor placement and amplifier behavior under PWM; practical range and accuracy depend on the sensing implementation. | The 0.049A/code figure is a transparent ideal-range arithmetic example, not a measured FOC resolution or torque-ripple prediction. | TI source reviewed October 3, 2026 |
| Kollmorgen, I²t Motor Overload Protection | One documented algorithm accumulates current squared above nominal over time and compares it with a product-specific limit; this is not a universal drive formula. | This is one motor-overload implementation. Drive protection, motor protection, filtering, thresholds, and recovery behavior vary by product. | Kollmorgen source reviewed October 3, 2026 |
Review your PMSM drive shortlist
Share the motor, current duty, cooling condition, and control requirements with our engineering team before finalizing an RFQ.
| Parameter | 100A Target | Lower-current option | System Impact |
|---|---|---|---|
| Power path and thermal | Validate current path, losses, and cooling against the vendor thermal data | Lower current may reduce resistive loss; compare actual path resistance and duty | At equal phase-path resistance, 100A has 4x the instantaneous I²R loss of 50A. Actual resistance, switching loss, duty cycle, and cooling differ by design. |
| Connector and cabling | Check conductor and connector sizing against the actual duty | Check conductor and connector sizing against the actual duty | Connector size follows system current, voltage drop, temperature rise, and installation rules; it cannot be inferred from a drive class label alone. |
| DC bus energy | Calculate bus rise and braking needs from system energy | Calculate bus rise and braking needs from system energy | Regenerated energy depends on the moving system and deceleration profile; current class alone does not define the DC-bus energy. |
| FOC current sensing | Verify current-sense range, error budget, sampling, and low-speed torque performance | A tighter range can improve ideal code size if peak headroom remains adequate | A wider analog measurement span maps more amps per ideal ADC code, while usable FOC accuracy also depends on sensor, amplifier, ADC, noise, offsets, and sampling. |
| Procurement cost | Compare drive, thermal, cable, and validation cost from supplier data | May lower BOM and qualification burden; verify with a like-for-like quote | Do not choose a lower rating from this screen alone; compare measured duty, overload behavior, motor requirements, and supplier quotations. |
Sizing and Current Sensing Trade-offs
A higher current rating can affect power-path, connector, and sensing choices, but performance and cost depend on the actual design. A wider sensing span maps more amps per ideal ADC code; verify sensor error, noise, bandwidth, sampling, and low-speed torque behavior on the selected hardware.
Risk Matrix
The highest-impact mistakes are usually not the headline current rating. They are thermal assumptions, regeneration handling, FOC sensing range, and switching/layout validation.
Qualitative engineering priorities only; marker positions do not represent measured field incident rates.
| Risk | Trigger | Mitigation |
|---|---|---|
| Thermal shutdown or unsafe surface temperature | Sustained high current in a sealed or poorly coupled joint | Specify cooling plate, ambient temperature, duty cycle, and firmware thermal protection state in the RFQ. |
| Low-current torque noise in PMSM | A wide current-sense range is used where the joint operates at much lower current | Ask for the current-sense range and error budget, sensor type, FOC current-loop bandwidth, and low-current torque test data. |
| Regeneration over-voltage | High deceleration current pushes energy back to the DC bus | Review battery absorption, braking resistor sizing, and over-voltage trip thresholds. |
| EMI or switching instability | High-frequency GaN switching is used without matching layout and filtering | Validate conducted/radiated emissions, layout parasitics, and motor cable length before freezing the PCB. |
Procurement Check
Questions to Ask Before Buying a 100A Drive
| Question | Why it matters |
|---|---|
| What is the continuous phase current rating? | Distinguishes a model’s continuous rating from its peak rating and the conditions attached to each. |
| What pulse current is allowed, for how many seconds, and at what repetition rate? | Prevents the common error of treating a one-time pulse rating as a robot duty-cycle rating. |
| What cooling surface, ambient temperature, and enclosure assumptions were used? | Makes the thermal number reproducible in the actual robot joint. |
| What motor inductance, PWM frequency, and FOC loop bandwidth are supported? | Confirms the drive can control the low-inductance PMSM motor cleanly, not just survive the current. |
| How is regenerative energy handled? | High-current braking can fail through DC bus over-voltage even when torque output is adequate. |
Scenario Checks
What Current-Only Examples Can Tell You
These illustrative cases use phase RMS current inputs to show what the numeric comparison can and cannot conclude. They are not measured product results or supplier recommendations.
| Case | Input assumption | Outcome |
|---|---|---|
| Humanoid knee jump recovery | 35A continuous, 95A peak, 1.5s pulse, chassis conduction | Below the numeric references, but current-only screening cannot confirm fit. Match the vendor current basis and request pulse, repetition, and thermal limits. |
| AGV steering actuator | 18A continuous, 45A peak, 2s pulse, sealed enclosure | Below the numeric references. Compare appropriately rated options using measured duty, motor requirements, sensing performance, and like-for-like quotations. |
| Direct-drive robot shoulder | 72A continuous, 100A peak, 4s pulse, active cooling | Peak reaches the numeric reference with no screen margin. Confirm rating basis, pulse repetition, cooling, and supplier thermal protection data. |
Frequently Asked Questions
Next Steps
- Browse GaN Servo Drives to compare compact drive families after your current envelope is known.
- If you plan to design the PCB into your own housing, check the 100A board level servo drive integration guide.
- Start with the GaN low-voltage servo drive family when compact 24V to 60V robotics packaging is the main constraint.
- Compare the 48V servo driver board path if the actuator architecture is centered on a bare-board integration.
- Review the GaN servo drive selection guide for thermal management, FOC current sensing, and integration review.
- Review humanoid robot joint requirements when the 100A request comes from compact knee, hip, or shoulder actuators.
Inquiry Email
Include voltage, current, motor, encoder, protocol, board envelope, and quantity stage.