FOC (PMSM/BLDC) | Start-Up & Low-Speed Tuning

What we do

We make sensorless Field-Oriented Control (FOC) behave like you do have a sensor—especially at start-up and low speed where estimators struggle. We engineer robust observers, clean start sequences, and handover logic so your PMSM/BLDC drive delivers smooth torque, quiet acoustics, and reliable restarts.

Outcomes we target

  • Confident start-up on loaded machines (no stall, no kickback)
  • Stable low-speed torque with minimal ripple and cogging
  • Silent transition from open-loop to closed-loop sensorless control
  • Wider operating envelope (cold/warm, battery sag, high saliency)
  • Clear fault recovery: loss-of-sync detection and graceful re-starts

Services

  • Observer Design & Tuning – SMO, MRAS/Luenberger, PLL/back-EMF, EKF (when budgets allow); estimator bandwidth vs. noise trade-offs and delay compensation.

  • Start-Up Sequences – initial alignment, I-F ramp/open-loop V/f, current-limited ramps, and seamless handover criteria to closed-loop.

  • Low-Speed Enhancements – High-Frequency Injection (HFI) for saliency tracking, demodulation filters, and anti-cogging feedforward.

  • Parameter Adaptation – Rs(T) and flux linkage correction, inertia/friction ID, bus-voltage feed-forward and field-weakening integration.

  • Ripple & Acoustics – SVM timing, dead-time comp, MTPA biasing, dq cross-coupling and notch/averaging for speed estimate.

  • Protections & Recovery – loss-of-lock detection, stall handling, re-sync strategies, brown-out & low-temperature handling.

  • Data & Test Harness – logging of estimators, phase currents/voltages, dq variables; scripted sweeps for envelope validation.

  • Integration – MCSDK/HAL/LL modules, ISR-safe estimator updates, LUTs for temperature/speed zones.

Deliverables you receive

  • Sensorless Control Pack: tuned observer parameters, start-up/handover logic, and safety thresholds (headers/CSV + notes).

  • Code Patches: estimator module(s), HFI demodulation (if used), and handover state machine for CubeIDE/MCSDK (HAL/LL).

  • Validation Report: start-up success matrix, low-speed torque plots, acoustic/ripple metrics, and boundary-case results.

  • Test Scripts & Logs: reproducible sweeps (Python/MATLAB) and acceptance checklist.

  • Handover Session: 60–90 min walkthrough and Q&A.

Technical stack

  • Motors: IPMSM/SPMSM, surface & interior saliency; BLDC in FOC or 6-step→FOC migration

  • Observers: SMO, MRAS/Luenberger, back-EMF PLL, EKF; optional HFI (sinusoidal or square injection)

  • Peripherals: TIM1/8 center-aligned PWM, ADC injected sampling synced to PWM, DMA pipelines, OPAMP/COMP, DFSDM

  • MCUs: STM32F3/F4/F7, G4, H7, U5

  • Tooling: X-CUBE-MCSDK, STM32CubeIDE/CubeMX, HAL/LL; FreeRTOS compatible

How an engagement works

  1. Discovery (30 min) – mechanics, load profile, and problem symptoms.

  2. Baseline & Data – capture start-ups, low-speed runs, estimator traces.

  3. Design & Integration – observer choice, start-up/handover logic, low-speed aids (HFI if needed).

  4. Validation – envelope sweeps, temperature/bus-voltage corners, abuse tests.

  5. Handover – parameters, code, reports, and team training.

What we need from you

  • Motor datasheet (poles, Rs, Ld/Lq if known, Ke/Kt), inverter schematic, sensing method (shunt/Hall/LEM)

  • DC-bus range, PWM freq, ADC timing windows, mechanical inertia/friction (if known)

  • Operating envelope: min/max speed & torque, start-up load conditions

  • KPIs (e.g., start-up success ≥ 99%, low-speed ripple ≤ X %, restart time ≤ Y s)

Packages

  • Sensorless Audit  – root-cause analysis, observer/start-up plan, acceptance tests.

  • Tuning Sprint – observer tuning + start-up/handover integration, initial validation.

  • Production Readiness – HFI or advanced aids, corner-case robustness, documentation & training.
    (Messaging tip: use “transparent, cost-effective pricing” or a clear price-match policy rather than “cheapest”.)

Example use cases

  • E-bikes & scooters – hill starts without kickback, quiet crawl speeds.

  • Robotics/AGV/AMR – precise low-speed positioning and smooth micro-moves.

  • Pumps/Compressors – loaded start-ups, sag-tolerant restarts, lower heat.

  • Fans/HVAC – whisper-quiet low-RPM operation with stable torque.

FAQ

Can you do zero-speed sensorless?
We use HFI to track saliency at standstill/near-zero and blend to back-EMF/SMO as speed rises.

Is HFI always required?
No. Many SPMSM/BLDC systems meet targets with tuned SMO/MRAS and robust start-up/handover; HFI is reserved for tough low-speed specs or high saliency.

Will this fit my MCU budget?
Yes—estimators are ISR-tight. HFI adds modest CPU; we size it to your loop time.

What about field-weakening?
Our observers and schedulers handle weakened flux; we validate transitions across base speed.

How do you prevent loss-of-sync?
Plausibility checks on back-EMF/observer residuals, adaptive bandwidth, and torque-limited ramps; immediate safe fallback on faults.