Development of a High-Performance Sensorless BLDC Fuel Pump Driver with CANopen Control for Automotive Application

1. Introduction

This case study details the development of a high-power sensorless BLDC motor driver designed for use in advanced motorsport fuel systems. The driver was engineered to operate reliably at 24V and up to 50 A continuous current, providing precise electronic control of high-performance fuel pumps through a CANopen communication interface.

The project’s objective was to deliver a robust, thermally efficient, and compact control unit capable of sustaining extreme environmental and mechanical stress while maintaining exceptional control accuracy and protection integrity. The deliverables comprised hardware and embedded firmware, fully validated for production deployment in a professional motorsport environment.

The final system provides smooth, sensorless operation of the fuel pump across a wide speed range, seamless CANopen integration with existing vehicle control networks, and advanced real-time protection. The result is a driver that combines high-power density, durability, and intelligent communication—essential characteristics in the performance-critical context of competitive motorsport.

2. Project Background and Objectives

Motorsport fuel systems demand precise, reliable, and rapid control of pump flow to respond instantly to engine load and dynamic conditions. The client, a European motorsport technology company, required a bespoke controller to manage next-generation high-flow pumps used in endurance and performance racing.

The project brief specified several key requirements:

• Continuous operation at 24V and 50 A, with headroom for transient current peaks.
• Sensorless BLDC control to minimise size, weight, and mechanical complexity.
• Full CANopen integration, enabling seamless communication with the engine control unit (ECU) and data acquisition systems.
• High thermal efficiency and sustained performance under extreme heat and vibration.
• Comprehensive protection, including overcurrent, overtemperature, phase fault, and loss-of-communication safeguards.
• Compact, lightweight construction compatible with motorsport packaging constraints.

The project thus aimed to develop a dedicated high-power controller that not only met these functional requirements but also exhibited the build quality, consistency, and resilience expected in professional motorsport.

3. System Overview

The fuel pump driver was designed as a dedicated BLDC control unit consisting of two primary layers:

1. High-power inverter hardware, optimised for continuous 50 A operation with exceptional thermal performance.
2. Embedded firmware, responsible for sensorless commutation, current regulation, fault handling, and CANopen communications.

The system interfaces with the vehicle’s control network via CANopen, allowing real-time speed or flow control commands, status monitoring, and fault reporting. The architecture is modular, allowing adaptation to different pump ratings or communication mappings without hardware modification.

4. Hardware Design

4.1 Power Stage

The driver’s hardware was engineered around a three-phase inverter topology optimised for efficiency and robustness. Key design priorities included low switching losses, current handling capability, and effective heat dissipation.

High-performance MOSFETs with low R_DS(on) values were selected to minimise conduction losses, while a carefully tuned gate-drive network ensured fast, clean transitions with minimal switching noise. The PCB was designed with heavy copper layers and thermal vias directly connecting the power stage to the heatsink interface, achieving superior current distribution and temperature control.

4.2 Thermal Architecture

At 50 A continuous operation, thermal management was a central challenge. The solution combined multiple layers of thermal optimisation:

• Direct-path heat conduction from MOSFETs and shunt resistors to a metal baseplate.
• Finite Element Analysis (FEA) to model temperature gradients and optimise copper pour thickness and spacing.
• Low-impedance current sense paths to minimise power dissipation in measurement circuits.
• Use of automotive-grade components rated for extended temperature operation.

The result was a power stage capable of maintaining safe junction temperatures under continuous load in environments exceeding 85 °C ambient temperature.

4.3 Mechanical Design and Environmental Robustness

The controller was packaged in a sealed, vibration-resistant aluminium enclosure, designed to meet the mechanical durability standards typical of motorsport electronics. Key features included:

• Encapsulation of sensitive components for resistance to oil, fuel, and moisture.
• High-strength mounting points to prevent mechanical stress on solder joints.
• Shielded wiring interfaces to maintain EMC performance even in noisy engine bay environments.

The enclosure design balanced mass reduction with thermal conduction, ensuring both strength and efficient heat transfer to the mounting surface.

5. Firmware Architecture

The firmware was developed in C, structured into modular layers to support scalability and robust real-time operation.

5.1 Control Core

The motor control core implements sensorless BLDC commutation with precise current control and speed regulation. An adaptive estimation algorithm provides reliable startup and smooth operation across a wide speed range, even under variable pump loads. The control loops are executed within a deterministic scheduler, ensuring consistent timing at high switching frequencies.

5.2 Current Regulation

To maintain linear response and protect the fuel pump under rapid transients, the firmware implements real-time current limiting and torque control. Current feedback is sampled synchronously with PWM updates to ensure accurate phase current reconstruction. Advanced filtering techniques provide clean measurement data even under high electromagnetic noise.

5.3 CANopen Communication Layer

The driver communicates via CANopen, providing compatibility with industry-standard control networks and diagnostic tools. The firmware includes:

• Object Dictionary compliant with CANopen conventions, allowing access to control and monitoring parameters.
• Process Data Objects (PDOs) for high-speed data exchange with the ECU.
• Service Data Objects (SDOs) for configuration and calibration.
• Heartbeat and Node Guarding for network supervision.
• Customisable mapping to align with the client’s control strategy and ECU data model.

This structure allows the driver to operate as a fully addressable network node, supporting both command-based and autonomous operation modes.

5.4 Fault Handling and Diagnostics

A real-time diagnostic layer continuously monitors current, voltage, and temperature. Faults are classified and handled according to severity, with immediate shutdown for critical events and automatic recovery for transient conditions. Diagnostic information is transmitted over CANopen, enabling external logging and analysis.

6. Thermal and Electrical Efficiency

6.1 Design Optimisation

The driver’s thermal performance was optimised through a combination of hardware design, control strategy, and firmware-level current management. Power losses were minimised using:

• Low-resistance components and optimised copper geometry.
• High-frequency PWM control to reduce current ripple.
• Adaptive dead-time management to reduce switching overlap.
• Temperature-aware current limiting, dynamically adjusting output to maintain safe thermal operating margins.

6.2 Efficiency Results

Testing demonstrated that the controller achieved >95% overall efficiency at nominal load and maintained full-load operation (50 A continuous) for extended durations without thermal derating. The efficiency was further enhanced by the firmware’s ability to adjust switching parameters dynamically based on real-time thermal feedback.

This balance between power density and reliability was a defining success criterion, enabling continuous operation under the intense thermal conditions typical of racing applications.

7. Fault Protection and Safety

Given the high energy levels involved, the system required rapid fault detection and protective action. Key protection mechanisms included:

• Phase current over-limit protection, with hardware-level comparators providing sub-microsecond shutdown.
• DC bus over-voltage and under-voltage protection, preventing unsafe operating conditions.
• Temperature monitoring of critical components with programmable thresholds.
• Loss-of-communication timeout, ensuring the pump returns to a safe state if CANopen control is lost.

The firmware’s fault management strategy integrates closely with the CANopen diagnostic model, ensuring that all events are recorded and reported to the network master. Engineers can retrieve detailed logs for post-event analysis, greatly simplifying troubleshooting during development and race operations.

8. Validation and Testing

The driver underwent a comprehensive validation program designed to verify electrical, thermal, and mechanical performance under real-world racing conditions.

8.1 Electrical Validation

Bench testing covered a range of fuel pump loads, confirming stable sensorless commutation and precise current regulation. The unit maintained consistent operation across a wide supply voltage range and during rapid command transitions from the CANopen master.

8.2 Thermal Characterisation

Thermal cycling and endurance tests confirmed that the controller could operate at full current load indefinitely without exceeding design limits. High-speed thermal imaging was used to validate FEA predictions and verify uniform heat distribution.

8.3 Vibration and Environmental Testing

The assembly was subjected to motorsport-grade vibration profiles and temperature extremes to validate mechanical integrity. The driver maintained full functionality under sustained vibration and shock levels representative of engine-bay mounting in endurance race vehicles.

8.4 EMC Testing

The design was verified for electromagnetic compatibility to ensure reliable operation alongside other high-frequency systems such as ignition modules, telemetry radios, and ECUs.

9. Production and Integration

After successful validation, the design was transitioned to production. The controller’s architecture allows easy adaptation for different pump power levels or form factors by scaling key power-stage components.

Manufacturing documentation was generated, including assembly drawings, test procedures, and calibration guidelines. A factory-level test routine was developed to validate each unit’s CANopen communication, thermal calibration, and fault detection functionality.

The driver integrates seamlessly with the client’s existing CANopen-based vehicle control infrastructure, enabling centralised management of pump performance and diagnostics. Firmware updates can be deployed over the CAN network, allowing continued refinement without physical access to the hardware.

10. Outcome and Performance Summary

The completed high-performance fuel pump driver achieved or exceeded all specified targets:

In live race testing, the controller demonstrated flawless reliability and thermal stability. Engineers reported a marked improvement in pump response time and system diagnostics, while the CANopen integration simplified calibration and real-time monitoring during both dyno and track sessions.

11. Conclusion

The development of the 24V, 50 A CANopen-controlled sensorless BLDC fuel pump driver represents a significant advancement in compact, high-efficiency power electronics for motorsport. Through a combination of careful thermal design, robust mechanical engineering, and intelligent firmware architecture, the system delivers exceptional reliability and control precision under extreme conditions.

Its success underscores the value of a system-level design approach—balancing electrical, mechanical, and thermal disciplines—to meet the uncompromising demands of high-performance racing environments.

The resulting controller not only meets the immediate requirements of the client’s fuel system but establishes a flexible foundation for future high-power control applications within automotive and aerospace domains, where efficiency, reliability, and communication integration remain paramount.