Motor Drive Protection | Overcurrent, Fault Handling, Testing

What we do

We design fast, reliable protection for motor drives—so faults turn into controlled events, not destroyed hardware. From overcurrent/short-circuit and over/undervoltage to thermal, desaturation, and stall conditions, we implement hardware-first trips with firmware fallback, clean fault handling, and repeatable test procedures.

Outcomes we target

  • Sub-µs hardware shutdown on shoot-through/desat; deterministic firmware responses

  • Stable fault state machine (latched, auto-retry, limp) with clear diagnostics

  • Fewer field failures via SOA-aware limits, thermal derating, and EMC-robust sensing

  • Documented acceptance criteria and traceable test evidence

Services

  • Protection Architecture – partitioning of hardware (gate driver/DESAT, comparators, BKIN) and firmware (ADC watchdogs, timers) with safe states.

  • Overcurrent & Short-Circuit – DESAT networks, blanking, soft-shutdown, shunt/Hall/LEM sizing, Rogowski options; fast paths to TIM BKIN/BRK.

  • Over/Undervoltage & Brown-Out – DC-bus sensing, surge filters, crowbar/bleed strategy, firmware derating, BOR thresholds.

  • Thermal & SOA Management – junction/case/board sensors, thermal models, foldback, cooldown timers, fan/pump control.

  • Observer & Stall Protections – sensorless loss-of-sync, position/speed plausibility, stall detection, torque limiting.

  • Firmware Fault Handling – fault latching, debounce, timestamping, error codes, safe torque off (STO) interface if present.

  • EMC/ESD Robustness – filtering, grounding/shielding guidance, comparator hysteresis, Schmitt inputs, digital filtering with phase awareness.

  • Test Planning & Fixtures – repeatable short-tests (STG/STB), load abuse, brown-out, thermal ramps; HIL/SIL scripts, datalogging.

  • Design Review – gate driver selection, Miller clamp, dead-time, snubbers/TVS, layout review (Kelvin shunts, current loops).

Deliverables you receive

  • Protection Strategy Doc (PDF): block diagrams, thresholds, timing budgets, safe states.

  • Schematics & BOM Notes: DESAT network values, shunt choices, filters, TVS/snubber specs.

  • Firmware Module: protection manager (HAL/LL) with ISR hooks, ADC watchdogs, state machine, diagnostic events.

  • Test Plan & Reports: procedures, acceptance limits, oscilloscope/LA captures, pass/fail summary.

  • Failure Tree & FMEA Lite: key hazards, mitigations, residual risk notes.

  • Handover Session: 60–90 min walkthrough for your team.

Technical stack

  • Power stages: IGBT/MOSFET inverters, PMSM/BLDC drives, DC/BLAC/IM

  • Sensors: shunt, Hall/LEM, Rogowski, NTCs, on-die temps

  • Gate drivers: DESAT/soft-shutdown, Miller clamp, UVLO, active clamping

  • STM32 features: TIM1/TIM8 BKIN/BRK kill inputs, dead-time/BDTR, ADC analog watchdog, VREFINT monitoring, COMP/OPAMP, DFSDM, BOR/PVD

  • Standards alignment: support for customer flows targeting IEC/UL/EN (e.g., ISO 13849 concepts, STO interfaces) on a best-effort basis*

* We don’t issue certifications; we prepare evidence and designs to support your certification path.

How an engagement works

  1. Discovery (30 min) – topology, power levels, failure history, KPIs.

  2. Architecture & Plan – protection tree, thresholds, timings, test list.

  3. Implementation – hardware values, firmware modules, state machine, logs.

  4. Validation – execute tests (bench/HIL), corner cases, EMC stress.

  5. Handover – reports, parameter sets, training, next-steps.

What we need from you

  • Schematic/PCB (power & control), gate driver P/N, shunt/gain details

  • Motor & inverter ratings (Vdc, Idc/phase, switching freq), thermal limits

  • Control stack (MCSDK/HAL/LL), current sampling method & PWM mode

  • Safety targets (e.g., max fault energy, shutdown time, retry policy)

Packages (example framing—set your own prices)

  • Protection Audit  – risk review, thresholds/timing budget, fix plan.

  • Implementation Sprint  – hardware values, firmware manager, initial tests.

  • Production Hardening – abuse testing, EMC robustness, documentation & training.
    (Positioning tip: “transparent, cost-effective pricing” or a clear price-match policy performs better legally than “cheapest”.)

Example use cases

  • E-mobility/inverters – DESAT + BKIN hard-kill, soft-shutdown, controlled restart.

  • Pumps/Compressors – brown-out ride-through with current/torque foldback.

  • Robotics/AGV – overload protection with thermal derating and safe limp mode.

  • Fans/HVAC – acoustic-friendly current limiting and restart strategies.

FAQ

How fast is “fast” protection?
Hardware trips via DESAT/COMP→BKIN are typically sub-µs to a few µs; firmware follows with safe sequencing.

Will protection cause nuisance trips?
We balance blanking/hysteresis and provide filtered thresholds plus event debouncing and retry logic.

Do you support sensorless drives?
Yes—observer plausibility checks and stall detection integrate with the protection manager.

Can you help with STO?
We interface with certified STO modules and ensure firmware reaches a safe state; certification remains with your safety HW vendor.