Custom driver board design for servo, stepper and BLDC motors

Feedback and control loops in servo drive design

Servo does not, on its own, describe the motor’s electrical type; it describes a control architecture that regulates position, speed or torque using feedback. A suitable PMSM/BLDC or stepper motor can be used in a closed-loop system according to the task. Encoder resolution and interface, current feedback, mechanical backlash and load changes are assessed together. Current, speed and position loops are tuned and tested with the actual mechanism; spinning an unloaded motor alone does not validate an axis.

Current regulation and motion profiles in stepper driver boards

Stepper motor applications require phase-current regulation, microstepping, acceleration ramps and holding requirements at standstill to be planned together. A STEP/DIR or communication-based command interface is selected to suit the machine’s control architecture. The microstep count alone does not establish mechanical positioning accuracy. Lost steps under load, vibration, heating and restart behaviour are examined; an encoder-based closed-loop approach is considered where needed.

Choosing commutation and FOC for BLDC/PMSM drives

For three-phase BLDC/PMSM motors, six-step commutation and field-oriented control (FOC) are compared against the motor design and required motion behaviour. The choice of Hall sensors, an encoder or sensorless estimation depends on starting, low-speed operation, load changes and stopping requirements. One algorithm is not applied to every motor. Phase-current sampling and PWM timing are designed together; the selected approach is validated with the motor across the intended operating range.

Power stage, gate driver and driver PCB layout

Power switches, gate drivers, the current-sensing chain and supply circuits are sized for the voltage, current, switching and thermal conditions. High-current paths, switching loops, sensitive measurement references and heat transfer are considered together on the PCB. Dead time, overcurrent response and undervoltage behaviour involve both hardware and firmware. A possible rise in DC-bus voltage during braking is also assessed against the motor’s stopping scenario.

Machine communication, parameters and fault behaviour

Commands, acceleration limits, motor parameters and fault records are defined in the drive firmware. CAN, RS-485 or another suitable interface is selected according to the existing controller and protocol requirements. Expected behaviour is defined for lost communication, sensor loss, excessive temperature and power cycling. The drive’s protective functions and the machine’s safety requirements are defined separately, with the relevant architecture and validation scope.

Prototype validation, production preparation and technical delivery

Initial power-up uses a controlled supply and defined limits; load, speed-change, stopping and fault scenarios follow. Current measurements, temperatures, feedback and communication results are tied to the hardware revision and firmware version. Acceptance criteria are written for each project; no unmeasured power, precision or efficiency figure is promised. Any required external laboratory work is planned separately.

For the approved design, schematics, PCB source files, manufacturing files, the bill of materials, developed firmware and test descriptions are included in the delivery scope. Sample production and assembly are provided only as part of the customer project we develop. Programming, parameter loading and functional checks are organised for subsequent batches to complete repeat-production preparation.