EV Inverter Non-Overlap Control via Single Isolation Feedback
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Solution Overview
Problem
Inverters for electric vehicles face issues with overlapping turn-on events of opposing phase switches, which can damage the system, and the dead time between switching events leads to inefficiencies, as existing non-overlap enforcement methods are either open-loop or require multiple galvanic isolation channels, increasing costs and defect-related failures.
Innovation Solution
A closed-loop non-overlap enforcement architecture that uses a single galvanic isolation channel to confirm the off-state of one switch before allowing the opposing switch to turn on, employing a burst of galvanic pulses and a roundtrip timer to ensure proper timing and prevent shoot-through events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dead time is increased between switching events, then overlapping turn-on events are prevented, but inverter efficiency deteriorates
Solution Approach 1:
The patent implements a closed-loop feedback mechanism where the actual off-state of a phase switch is detected and fed back to the PWM controller. The PWM controller uses this feedback to dynamically adjust the enable signal timing, ensuring the opposing switch is confirmed off before allowing turn-on. This replaces fixed dead time with adaptive timing based on real-time switch state feedback, preventing overlaps while minimizing unnecessary dead time losses.
2Reliability
If multiple galvanic isolation channels are used for non-overlap enforcement, then shoot-through prevention is improved, but device complexity and cost increase
Solution Approach 1:
The patent makes the primary galvanic isolation channel multi-functional by using it for both PWM signal transmission and off-state feedback. The PWM controller sends enable signals through the galvanic interface and simultaneously receives feedback about the actual switch off-state through the same interface. This eliminates the need for separate dedicated feedback galvanic channels while maintaining shoot-through prevention capability.
3Device complexity
If fixed dead time is used between switching events, then non-overlap enforcement is simplified, but timing precision and reliability deteriorate
Solution Approach 1:
The patent transitions from static fixed dead time to dynamic adaptive timing. The system continuously monitors the actual switch off-state through feedback and adjusts the enable signal timing accordingly. This dynamic approach adapts to varying switching conditions and ensures reliable non-overlap enforcement regardless of changes in load, temperature, or component characteristics.
Data Source
AI summary
A system includes: an inverter including: a first galvanic interface to separate a first high voltage area from a low voltage area; a first low voltage controller in the low voltage area, the first low voltage controller configured to send a first control signal using the first galvanic interface to a first high voltage controller in the first high voltage area; a second galvanic interface to separate a second high voltage area from the low voltage area; and a second low voltage controller in the low voltage area, the first low voltage controller configured to send a second control signal using the second galvanic interface to a second high voltage controller in the second high voltage area, wherein the second low voltage controller is configured to provide an output latch signal to the first low voltage controller and receive an input latch signal from the first low voltage controller.