Study Examination: Creation of a Management System for Electric Motors
Sierra Circuits Unveils High-Performance Motor Control PCB
Sierra Circuits, a leading printed circuit board (PCB) manufacturer, has announced the launch of a new high-current motor control PCB, designed to manage high currents and switching frequencies while ensuring signal integrity, thermal management, and noise reduction.
Key Design Specifications and Measures
The design process begins with a thorough evaluation of the circuit's requirements, including controlled impedance, routing density, PCB material, and operating frequency. To maintain signal integrity at high switching frequencies, controlled impedance traces are marked in schematics and closely managed throughout the board layout.
For microstrip construction, an unbroken ground plane beneath traces is used, while for stripline construction, ground or power planes are placed over, under, and beside differential pairs. Stitching vias near signal vias are added to provide return current paths between reference planes, and stitching capacitors are symmetrically placed for differential pairs to maintain signal quality.
Sierra Circuits uses precision equipment to measure impedance on PCBs and coupons, ensuring traces meet the required specifications given board size and layer complexity. High current capability requires wide and thick copper traces, adequate thermal vias, and possibly copper pours for heat dissipation.
Common Challenges in Component Placement and Routing
Managing high switching frequencies, noise and EMI reduction, layer transition effects, space constraints, and thermal management pose challenges in component placement and routing for high-current motor control PCBs.
To minimize crosstalk and noise coupling, components are grouped according to their functions using the same topologies. Over a thousand components are incorporated in the motor control board, making component placement challenging.
Board Features and Specifications
The motor control board operates at a 50 MHz frequency and has an ethernet connection of 100 Mb/S. The board material is FR-370 HR, offering maximum thermal performance and reliability. The locations of the input connectors are fixed, affecting the component placement, which is critical.
The board is an IPC class-3 design, undergoing a thorough inspection to ensure high quality. The IPC Class 3 Design Guide contains 8 chapters, 23 pages, and is a 35-minute read. It covers IPC guidelines for manufacturing defects, assembly processes, and sets the level of acceptance criteria.
The design includes a brushed DC motor controller for efficient control over motor torque and speed. To prevent interference, components are grouped according to their functions using the same topologies. The motor control board is an 8-layered board with dimensions of 192 mm x 141 mm.
Overcoming Fabrication Challenges
Sierra Circuits' DFM engineers examine all vital specifications, including high-current requirements, and set up suitable fabrication rules. Controlled impedance traces of 100 ohms differential and 50 ohms single-ended are required for signal integrity.
The motor control board requires current up to 25 amps, necessitating the splitting of high-current traces into different board layers. Sierra Circuits resolves the challenges of fabricating a complex board by establishing correct design constraints.
CAN Bus interfacing is implemented in this design, used in complex, robust designs, majorly in the automotive and industrial sectors. The team reads a blog on "10 automotive PCB design guidelines" to ensure the design adheres to industry best practices.
Delivering Quality and Customer Expectations
Sierra Circuits delivers high-quality boards that meet their customers' expectations. The motor control board is designed to operate on a peak current of 30 amps and an average current of 20 amps. Motor controllers can be used in various propulsion systems, including electric cars, bikes, fuel pumps, motorbikes, multi-axis motion controllers, robotic motion controllers, servo motors, high-speed tape recorders, X-Y recorders, heavy-duty drives, and optical position encoders in stepper motors.
- The high-performance motor control PCB, unveiled by Sierra Circuits, is designed with controlled impedance traces to maintain signal integrity at high switching frequencies, a key aspect in data-and-cloud-computing technology.
- In the manufacturing industry, Sierra Circuits uses precision equipment to ensure that the copper traces on their PCBs meet the required specifications, a crucial factor in managing high currents and thermal management.
- To accommodate high currents and achieve noise reduction, the motor control board's design incorporates elements of finance and business, such as the use of wide and thick copper traces, adequate thermal vias, and possibly copper pours for heat dissipation.
