Redesign of Blower Motor Control
Redesign of Blower Motor Control in Patient Ventilator
Starting situation
IMT was commissioned by a leading developer and manufacturer of ventilation devices to undertake a critical engineering project. The customer had received an end-of-life ("EOL") notice for the microcontroller used in the blower control electronics circuit of one of their ventilators. Due to resource constraints on the customer’s side, IMT was entrusted with identifying and implementing a suitable replacement, along with the necessary hardware and software updates to the mainboard.
Feasibility Phase
IMT initiated the project with a Feasibility Phase to identify potential replacement components and assess necessary design architecture modifications. The team selected candidate components, built prototypes using development boards, and developed the required firmware. Performance tests were conducted at both the blower module level and the ventilator system level, ensuring that the new blower microcontroller met the specification requirements.
Development and Implementation
Following the feasibility demonstration, IMT proceeded with the final development of the blower mainboard and adaptation of the manufacturing test fixture. The existing EMS supplier was engaged to produce the new blower board prototypes and serial units.
In agreement with the customer, an "Integrated Solution" concept was implemented as the replacement for the EOL microcontroller. This concept was chosen for its superior fulfillment of technical requirements, expandability, reliability, life cycle management, cost-effectiveness, and size optimization. The solution comprised:
- A standard 32-bit microcontroller with a limited number of I/Os
- A brushless DC Pre-Driver with three half-bridges (six MOSFETs)
- Closed-loop regulation performed in software by back-reading the speed feedback signal of the brushless DC motor
- Component selection based on current and mid-term market availability
Engineering and Verification
IMT executed the hardware development of the mainboard, the software integration—including the adaptation of a new Hardware Abstraction Layer (HAL)—, and the redesign of the production test stand for the mainboard. The electronics were initially designed using Altium software but later translated into OrCAD to align with the toolset used by the customer's suppliers.
To ensure compliance, IMT provided comprehensive technical documentation, including:
- New electronics and software design specifications
- Verification test protocols and results
- Documentation required for submission to notified bodies and the FDA
Results
The project was successfully completed to the full satisfaction of the customer. The redesigned blower motor control system ensures continued operation of the ventilator while enhancing reliability, manufacturability, and regulatory compliance. IMT's expertise in embedded systems and medical device engineering played a crucial role in the seamless execution of this project.
