1. Introduction - the Project Brief
The project described in this case study details the design and development of a combined sensorless motor driver capable of controlling both brushless DC (BLDC) and asynchronous (induction) motors on a single hardware platform. Commissioned by a European client operating in a high-performance motion-control market, the project encompassed the full delivery lifecycle — from hardware design and firmware development through to software interface, production, and validation.
The resulting system operates within a 36–48 V DC range and is optimised for applications demanding high rotational speeds, exceeding 100,000 rpm for asynchronous motors and 50,000 rpm for BLDC configurations. It integrates advanced motor control algorithms, a configurable software interface, motor profile management, and a sophisticated fault-detection and recovery framework.
The project’s objective was to deliver a compact, high-efficiency control platform that offered both versatility and ease of configuration for end users, allowing multiple motor types and use cases to be supported without hardware changes.
2. Project Background and Objectives
The client required a multi-purpose motor controller for a range of precision electromechanical systems that utilise both BLDC and induction motors. Traditionally, these two motor classes demand separate control electronics due to fundamental differences in their commutation principles. Achieving a unified solution required a control architecture flexible enough to adapt dynamically to each motor type’s electrical and mechanical characteristics while maintaining high-speed operational integrity.
Key project goals included:
- Development of a universal hardware platform supporting both motor types without external switching or reconfiguration.
- Implementation of sensorless operation across the full speed range to minimise mechanical complexity and improve system reliability.
- Creation of a graphical software interface enabling setup, tuning, live monitoring, and data logging.
- Incorporation of motor profile storage, allowing rapid changeover between motor configurations.
- Design of a comprehensive fault management system capable of predictive protection, logging, and controlled recovery.
- Delivery of production-ready hardware, firmware, and software, fully tested to the client’s compliance standards.
3. System Overview
The system consists of three tightly integrated layers:
- Hardware Power Stage and Control Electronics – designed to operate efficiently in the 36–48 V DC range while supporting continuous current sufficient for high-speed operation.
- Embedded Firmware – managing all motor control, fault handling, and communication with the host interface.
- Software Interface – a PC-based application providing configuration, live control, and data visualisation for engineering and production use.
These components combine to form a modular architecture that can be configured during runtime to operate in either BLDC or asynchronous mode, with the firmware dynamically adjusting its control strategy based on the loaded motor profile.
4. Hardware Development
The hardware was designed around a compact, thermally optimised PCB layout capable of sustaining high current densities while maintaining electromagnetic compatibility and low noise operation. Key considerations included:
- Power stage design: The inverter stage was optimised for low switching losses and high-frequency operation, enabling efficient control at the upper end of the speed spectrum.
- Thermal management: Component placement and heat-sinking were modelled to maintain safe junction temperatures during prolonged high-speed operation.
- Isolation and safety: Galvanic isolation was provided between power and control domains to ensure robustness during transient events.
- Scalability: The design supports multiple power ratings with minimal modification, enabling future derivative products.
All circuitry was validated through simulation and prototype testing, with particular attention given to the layout of the gate-driver and sense paths to ensure accurate current feedback and low noise susceptibility — both critical for stable sensorless control.
5. Firmware Architecture
At the heart of the system lies a real-time embedded firmware layer that governs all aspects of motor control and system protection. The firmware was developed in C, with a modular structure that separates motor control, communications, and diagnostics tasks.
Key architectural features include:
- Unified control core: A shared core algorithm structure accommodates both BLDC and asynchronous modes, abstracting key variables such as current loops, torque references, and flux estimations into interchangeable modules.
- Dynamic configuration: When a motor profile is loaded, the firmware reconfigures control parameters, PWM limits, and timing constants automatically, removing the need for manual code changes.
- Data communication layer: A custom communications protocol ensures reliable, low-latency data exchange between the controller and the software interface, allowing real-time monitoring and tuning.
Firmware development followed a staged verification process including hardware-in-the-loop testing and automated fault-injection to validate protection mechanisms.
6. Software Interface
The software interface was a major deliverable and a key differentiator for the end customer. It provides engineers and operators with direct visibility into motor performance and enables both setup and live control of the driver.
6.1 Design Objectives
The interface was required to:
- Provide intuitive setup of motor parameters, such as rated voltage, pole pairs, current limits, and acceleration profiles.
- Enable live telemetry, displaying speed, current, voltage, and fault status in real time.
- Allow manual control of motor start/stop and reference commands for testing or demonstration.
- Support motor profile management, including creation, saving, loading, and exporting of profiles.
- Offer diagnostic tools for commissioning and production testing.
6.2 Implementation
The interface was built as a stand-alone desktop application communicating directly with the driver through a custom protocol. It features structured menus, graphical gauges, and data plots for clarity during high-speed operation. Real-time data buffering enables continuous trend recording without communication loss, even under heavy processing load.
For engineering teams, the tool doubles as a development utility, allowing firmware calibration and parameter tuning during prototype validation. For production users, it simplifies the loading of predefined profiles, ensuring consistent setup across multiple units.
7. Motor Profile Management
The motor profile storage system is one of the standout features of the driver. It enables a library of motor configurations to be stored locally and recalled instantly, greatly improving flexibility for the client’s end users who operate multiple motor models.
Each profile contains key electrical and mechanical parameters including:
- Nominal voltage and current limits
- Motor constants (Kv, resistance, inductance)
- Control loop gains and ramp profiles
- Fault thresholds and recovery behaviours
Profiles can be created and edited via the software interface, then saved either to local storage or directly written to the driver’s non-volatile memory. When loaded, the firmware automatically reinitialises control structures to match the stored parameters.
This feature reduces commissioning time significantly and ensures repeatability — a vital factor in production environments and test setups where rapid changeovers are common. It also allows the client to pre-configure profiles for their own customers, streamlining downstream deployment.
8. Fault Management and Diagnostic Framework
High-speed motor control presents unique risks, including overcurrent, overheating, desynchronisation, and power-stage stress. The developed driver therefore incorporates an advanced fault management and diagnostic framework designed to protect both the controller and connected equipment while maximising uptime.
8.1 Real-Time Protection
Protection mechanisms operate continuously in real time, monitoring current, voltage, and thermal data. Thresholds are dynamically adapted according to the active motor profile and operational mode. Fast-acting comparators ensure that critical faults — such as phase short circuits or bus overvoltage — trigger immediate hardware shutdown.
8.2 Fault Categorisation and Logging
Faults are categorised by severity:
- Critical faults (requiring full shutdown)
- Recoverable faults (such as transient over-temperature or communication loss)
- Advisory warnings (indicating operating conditions approaching limits)
All events are time-stamped and logged in non-volatile memory, allowing engineers to perform post-event analysis via the software interface.
8.3 Recovery and Predictive Logic
Where possible, the controller implements soft recovery, automatically attempting to restart after transient faults once safe conditions are restored. The firmware also includes predictive monitoring that analyses current draw and temperature trends to pre-emptively warn of mechanical or electrical degradation.
This holistic approach to fault management contributes significantly to equipment reliability and reduces downtime in continuous-operation environments.
9. Validation and Testing
The driver underwent an extensive validation program that included:
- Bench testing with both BLDC and asynchronous motors across the full voltage range.
- Thermal endurance trials, ensuring stable operation at maximum continuous load.
- High-speed operation testing exceeding 100,000 rpm on asynchronous motors, verifying rotor tracking and sensorless stability.
- Fault-injection tests to confirm protection system response times and data logging accuracy.
- Software validation, including communication stress tests and verification of all user interface features.
Each test stage produced structured reports shared with the client, ensuring full traceability and confidence in the design’s performance envelope.
10. Production and Deployment
Following validation, the design was transitioned to full production. The hardware was optimised for manufacturability, with particular focus on assembly efficiency, component sourcing, and thermal performance. The firmware and software were frozen at release versions and configured for field upgradability, allowing future refinements without hardware modification.
Comprehensive documentation was produced, including manufacturing drawings, test procedures, and user manuals. Training was provided to the client’s engineering team to support commissioning and ongoing product integration.
11. Outcome and Client Impact
The completed motor driver delivered substantial technical and operational benefits for the client:
- Unified control for both motor types simplified their product ecosystem and reduced inventory complexity.
- Rapid setup through the motor profile system cut commissioning time dramatically.
- Real-time diagnostics improved reliability and made troubleshooting more efficient.
- Compact hardware and sensorless design reduced overall system cost and maintenance requirements.
- High-speed capability opened new application domains where previously separate systems were required.
Feedback from field testing indicated strong performance consistency, low noise, and high thermal stability. The integrated software interface was particularly valued for its clarity and ease of use, enabling even non-specialist technicians to perform setup and analysis confidently.
12. Conclusion
The development of the combined sensorless BLDC and asynchronous motor driver represents a significant engineering achievement in versatile motor control. By unifying two traditionally distinct technologies into a single, efficient, and intelligent platform, the project delivered tangible value to the client — enabling faster deployment, reduced hardware costs, and enhanced diagnostic capability.
The inclusion of motor profile storage, real-time software interfacing, and advanced fault management provides a forward-looking foundation for future scalability. With firmware and hardware architectures designed to accommodate evolving control techniques and communication standards, the platform positions the client to address diverse and demanding applications across industrial, laboratory, and high-performance domains.