SER-DES Motor Drive Circuit Galvanic Isolation
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Solution Overview
Problem
The high cost and increased board space requirements of existing isolation circuits in three-phase motor drive systems, which necessitate multiple isolation channels to isolate driver circuits and sensors, lead to elevated silicon and PCB costs.
Innovation Solution
The implementation of serializer-deserializer (SER-DES) modules that convert parallel signals into serial data streams, reducing the number of isolation channels needed by grouping signals within isolation domains and using galvanic isolation channels to maintain synchronization between motor controller and power modules, thereby simplifying the design and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If full isolation is required between each driver and sensor in a three-phase motor system, then reliability and safety are improved, but device complexity and manufacturing cost increase significantly due to requiring twelve isolation circuits
Solution Approach 1:
The patent combines multiple isolation circuits into a single isolation channel by serializing multiple signals and transmitting them sequentially through one isolation barrier. Instead of using twelve separate isolation circuits for each driver and sensor, the invention merges them into a single channel that handles multiple signals over time, thereby reducing device complexity while maintaining the required isolation safety.
Solution Approach 2:
The patent employs periodic serialization of multiple signals, where control signals for different drivers and sensors are transmitted in alternating time slots through the single isolation channel. This periodic multiplexing allows the system to maintain full isolation capability while using only one isolation circuit, effectively resolving the contradiction between reliability and device complexity.
2Reliability
If twelve isolation circuits are provided to isolate each driver and sensor, then galvanic isolation and safety are maintained, but silicon manufacturing cost and PCB space increase
Solution Approach 1:
The invention merges the function of twelve separate isolation circuits into a single isolation channel by implementing signal serialization. Multiple control and feedback signals are multiplexed into a single serial data stream that passes through one isolation barrier, thereby maintaining galvanic isolation while dramatically reducing silicon manufacturing cost and PCB space requirements.
Solution Approach 2:
The single isolation channel is designed to be universal, handling multiple different signal types (control signals, feedback signals, sensor data) through time-division multiplexing. This multi-functional approach allows one isolation circuit to perform the work of twelve separate circuits, reducing manufacturing costs while maintaining isolation integrity.
Data Source
AI summary
A motor drive circuit includes a first serializer-deserializer (SER-DES) module that converts first SER-DES input signals into a first SER-DES output serial data stream. The first SER-DES input signals relate to motor control inputs or motor drive power outputs. A second SER-DES module converts a second SER-DES input serial data stream corresponding to the first SER-DES output serial data stream into second SER-DES output signals. The second SER-DES input signals relate to motor drive power outputs or motor control inputs. A serial isolation channel provides a galvanic isolation barrier between the first SER-DES module and the second SER-DES module. The serial isolation channel communicates the first SER-DES output serial data stream across the galvanic isolation barrier to provide the second SER-DES input serial data stream.