01
Six-step commutation
A direct, computationally efficient approach that commutates phases in six electrical sectors.
Consider when: simplicity and robust speed control matter more than minimum ripple or acoustic noise.
Brushless DC motor-control design
Custom BLDC motor control engineered around the motor, load and product.
Outer Reef develops the power electronics, sensing, embedded control and system interfaces required when an off-the-shelf drive cannot meet the application.
- Power electronics
- Embedded control
- Sensing + feedback
- System verification
Start with the operating envelope
The controller is one part of a coupled electromechanical system.
A useful design brief describes the motor, load, power source, duty cycle, environment and interfaces together. Those inputs drive the control strategy, power stage, sensing, thermal path and fault response.
Send us your application requirements- Motor and feedback
- Electrical parameters, pole pairs, Hall sensors, encoder or resolver, and available characterization data.
- Load and motion
- Torque-speed points, inertia, acceleration, holding behavior, reversals and required position or speed accuracy.
- Power and energy
- Bus voltage, source impedance, peak current, regeneration, brownout behavior and stored-energy constraints.
- Thermal and environment
- Duty cycle, ambient range, cooling path, enclosure, moisture, contamination, shock and vibration.
- Interfaces and safety
- Commands, communications, interlocks, safe states, fault response and higher-level system behavior.
- Production constraints
- Mechanical envelope, connectors, target volume, component lifecycle, programming, calibration and manufacturing test.
Control architecture
Choose the commutation and feedback strategy from the system requirements.
There is no universally best algorithm. Torque ripple, acoustic noise, starting behavior, low-speed control, efficiency, sensor cost and processor resources determine the right approach.
01CommandTorque · speed · position
02ControlState estimation · loops
03Power stageGate drive · switching
04Motor + loadElectromechanical output
02
Sinusoidal commutation
Smooth phase-current commands can reduce torque ripple and acoustic effects within the useful control bandwidth.
Consider when: smooth motion and lower audible noise are important and the operating range is well defined.
03
Field-oriented control
Transforms measured phase currents into rotating d-q coordinates so flux and torque-producing current can be regulated separately.
Consider when: dynamic torque control, efficiency, wide operating range or precise low-speed behavior justify the added sensing and computation.
Hardware and firmware, developed together
Close the gaps between the schematic, control code and physical machine.
Motor-control failures often appear at discipline boundaries. Co-design makes current sensing, switching behavior, timing, thermal limits, mechanics and communications visible in one engineering workflow.
Hardware
Power-stage architecture
MOSFET selection, gate drive, dead time, DC-link behavior and protection coordinated with the required operating envelope.
Hardware
Measurement and protection
Current, bus-voltage and temperature sensing designed with bandwidth, accuracy, isolation and fault response in view.
Hardware
PCB and thermal design
High-current paths, switching loops, grounding, heat spreading, connectors and mechanical constraints resolved as one layout problem.
Firmware
Commutation and control loops
Current, torque, velocity and position behavior implemented with timing, saturation and operating-state transitions defined.
Firmware
Feedback and estimation
Hall, encoder, resolver or sensorless feedback selected around starting behavior, low-speed needs, accuracy and fault tolerance.
Firmware
Diagnostics and communications
Fault logging, calibration, parameter management, bootloading and system interfaces integrated into the product architecture.
System
Motor characterization
Use available data or targeted measurement to establish parameters and operating limits needed for control and protection.
System
Electromechanical integration
Account for the transmission, load, mechanical resonance, cables, enclosure and host controller that influence real behavior.
System
Production readiness
Design for programming, calibration, traceability, test access, component availability and repeatable manufacturing checks.
Development path
Move from operating requirements to controlled, testable hardware.
The sequence adapts to program maturity. Existing electronics can be diagnosed or redesigned; new systems can begin with motor characterization and architecture tradeoffs.
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01
Define the envelope
Capture torque-speed points, inertia, duty cycle, supply limits, environment, interfaces and fault behavior.
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02
Resolve tradeoffs
Compare feedback, commutation, power-stage, processor, thermal and packaging options against measurable requirements.
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03
Prototype and bring up
Build in stages, validate supplies and gate drive, confirm sensing polarity and scaling, then commission control loops safely.
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04
Integrate the machine
Tune with the actual motor, transmission, load, cabling, enclosure and host-system commands.
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05
Verify and transfer
Exercise operating corners and faults, document results, and prepare programming, calibration and production tests.
Verification strategy
Test the controller against the conditions that can break the product.
Verification should connect measurable limits to system requirements. The exact plan depends on the application, risk profile and production environment.
AreaEvaluateWhy it matters
Electrical
Phase current, bus transients, switching behavior, current-loop response and protection thresholds.
Confirms control stability and electrical margin across normal and fault conditions.
Motion
Startup, low-speed behavior, torque-speed response, reversals, braking and load disturbances.
Shows whether the controller meets the machine-level behavior that matters to the user.
Thermal
Power-stage, PCB and motor temperatures across duty-cycle and ambient corners.
Identifies continuous limits, cooling needs and derating before enclosure or production choices become fixed.
Fault response
Sensor loss, stall, overcurrent, overtemperature, supply interruption and communications faults.
Confirms that detection, shutdown and recovery behavior match the system risk analysis.
Integration
EMC pre-compliance, cable effects, communications, mechanical resonance and production calibration.
Finds failures that do not appear when the controller is evaluated as an isolated bench assembly.
Built for the product around it
Motor-control design reaches beyond the control algorithm.
Packaging, connectors, thermal paths, service access, communications and production test can determine whether a controller works as part of a finished machine.
- Mechanical envelope and heat rejection
- Power, motor, feedback and host-system interfaces
- Programming, calibration and service access
- Assembly, inspection and production test strategy
- Component availability and lifecycle risk
Planning a custom controller
Questions that shape the engineering scope.
These answers describe typical engineering considerations. The right architecture depends on the motor, load and product requirements.
What information is needed to scope a custom BLDC controller?
Useful inputs include motor electrical data, torque-speed points, load inertia, duty cycle, supply limits, feedback devices, interfaces, environment, mechanical envelope, fault behavior, production volume and target cost. Missing data can become part of the characterization plan.
When should a BLDC system use sensors instead of sensorless control?
Hall sensors, encoders or resolvers are often appropriate when startup under load, zero-speed torque, precise low-speed motion or known rotor position is required. Sensorless methods can reduce wiring and hardware, but startup and low-speed observability need careful evaluation for the application.
Does every BLDC application need field-oriented control?
No. Six-step control can be a strong choice for applications with straightforward speed control and acceptable torque ripple. Sinusoidal or field-oriented control becomes more attractive when smooth torque, acoustic performance, efficiency, dynamic response or precise low-speed behavior carries more weight.
When does a custom controller make sense?
A custom design can be justified when available drives cannot satisfy the combined electrical, thermal, mechanical, communications, safety, cost or production requirements. An early comparison should include total integration burden, not only controller purchase price.
Can Outer Reef develop both controller hardware and embedded firmware?
The existing Outer Reef service offering includes custom motor-control hardware and embedded firmware. The project scope can cover either discipline or the combined controller, depending on the starting point and system responsibilities.
What should be planned for production transfer?
Typical needs include component lifecycle review, design-for-manufacture, programming and calibration flow, test points, manufacturing test limits, traceability, released documentation and a controlled path for firmware configuration.
Bring the system problem
Need a controller that fits the machine rather than the other way around?
Share the motor, load, power source and operating constraints you already know. An initial engineering discussion can identify the missing inputs and the right next step.