Galvanic Isolation Watchdog Timing for Noise Immunity
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Solution Overview
Problem
Conventional solutions for controlling noise interference between high voltage and low voltage domains in power switch driver circuits are inadequate, particularly in safety-critical applications like automotive systems, where noise from high voltage domains can corrupt control signals and lead to false shutdowns or errors.
Innovation Solution
The system employs a gate driver device that schedules watchdog commands and precision measurements using the duty cycle and frequency of PWM gate control signals to avoid noise-induced corruption across a galvanic isolation barrier, ensuring that data operations are timed to avoid noise interference from high voltage domain transitions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If galvanic isolation barriers are used to isolate low voltage control circuitry from high voltage power switches, then noise interference is reduced, but protection against noise corruption of control signals and measurements is insufficient
Solution Approach 1:
The system schedules watchdog commands and precision measurements to be executed at specific times relative to PWM transitions. By preliminarily determining safe time windows before noise occurs, the system proactively protects critical communications from corruption while maintaining galvanic isolation.
Solution Approach 2:
The system dynamically adjusts the timing of watchdog commands and measurements based on the PWM duty cycle and frequency. By making the communication schedule adaptive to changing operating conditions, the system maintains reliable noise-free communication across varying power switch operating states.
2Speed
If fast current switching is performed in the high voltage domain to drive power switches, then power switch operation speed is improved, but radiated noise and conducted noise on supply and signal lines increase
Solution Approach 1:
The system extracts critical communications (watchdog commands and precision measurements) from the noisy time periods by scheduling them to occur only during safe windows when PWM transitions are not occurring. This separates the critical data exchange from the noise-generating switching events.
Solution Approach 2:
The system implements periodic watchdog commands and measurements that are synchronized with the PWM cycle. By using periodic action aligned with the power switch operating rhythm, the system ensures critical communications occur at predictable, noise-free intervals.
3Measurement precision
If watchdog commands and temperature measurements are transmitted regularly across the galvanic isolation barrier, then monitoring accuracy is maintained, but data frames are corrupted by noise from power switch die
Solution Approach 1:
The system preliminarily identifies safe time windows relative to PWM transitions and schedules all critical communications within these windows. By planning communications in advance based on known noise-free periods, the system prevents data corruption before it can occur.
Solution Approach 2:
The system uses watchdog commands that provide feedback between the low voltage and high voltage domains. By scheduling these feedback mechanisms during noise-free periods, the system ensures reliable monitoring and detection of abnormal conditions without data corruption.
Data Source
AI summary
A control system (100, 200) and method (300) are provided where a first voltage domain circuit (111) and a power switch (121) operate in a first voltage domain and where a second voltage domain circuit (109) operates in a second voltage domain, where the second voltage domain circuit includes a gate driver circuit (202) for providing a control terminal driving signal (PWM1) to drive the power switch, and also includes a watchdog communication circuit (207) for scheduling watchdog communications between the first and second voltage domain circuits to be temporally separated from noise-inducing signal transitions in the control terminal driving signal.