Dynamic PWM Update Order for Power Converter Shoot-Through Prevention

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing software-based deadtime insertion methods in power converters for electric vehicles may fail to ensure correct pulse width modulation (PWM) command updates due to software running overtime or interruptions, leading to potential shoot-through conditions.

Innovation Solution

A controller-based algorithm that dynamically determines the update order for PWM commands for upper and lower switches based on the timing of their rising edges, ensuring consistent register values and preventing shoot-through by sequencing updates accordingly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If software-based deadtime insertion is used to update PWM commands, then the system can operate without additional hardware, but the update order may be incorrect when software runs overtime or is interrupted, leading to shoot-through conditions

Engineering Contradiction:

Improvehardware complexityVSAvoidPWM command update reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent applies dynamics by making the update order adaptive rather than fixed. The controller dynamically determines the update sequence based on the actual timing of rising edges detected in the PWM commands. This allows the system to adjust the update order in real-time according to the actual signal behavior, ensuring correct deadtime insertion even when software execution timing varies or interruptions occur.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements feedback by detecting the actual rising edge timing of PWM commands and using this information to determine the update order. The controller monitors the timing characteristics of the PWM signals and adjusts the update sequence accordingly, creating a closed-loop control mechanism that ensures reliable operation without requiring additional hardware.

Inventive Principle:

Principle #23Feedback

2Ease of operation

If a fixed update order is used for PWM commands, then the control logic is simple, but it cannot adapt to varying rising edge timings, potentially causing shoot-through conditions

Engineering Contradiction:

Improvecontrol logic simplicityVSAvoidadaptability to rising edge timing variations

Core Design Contradiction:

Ease of operationVSAdaptability or versatility

Solution Approach 1:

The patent transforms the static, fixed update order into a dynamic, adaptive sequence. Instead of always updating in the same order, the controller determines the update sequence based on the detected rising edge timings. This dynamic approach maintains relatively simple control logic while significantly improving adaptability to varying operating conditions and PWM signal characteristics.

Inventive Principle:

Principle #15Dynamics

3Reliability

If additional hardware is added to ensure correct PWM command updates, then update reliability improves, but device complexity and cost increase

Engineering Contradiction:

ImprovePWM command update reliabilityVSAvoidhardware complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces potential hardware-based solutions with a software/control algorithm approach. Instead of adding hardware circuits to enforce update order or detect timing, the invention uses software-based detection of rising edges and conditional logic to determine the appropriate update sequence. This substitution maintains high reliability while avoiding additional hardware complexity and cost.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS11557999B2Dynamic pulse width modulation update

Publication Date: 2023.01.17 FORD GLOBAL TECH LLC

AI summary

A control method includes sequentially updating a next cycle pulse width modulation command for each of an upper switch and lower switch of a phase leg of a power converter according to an order defined by timing of a rising edge of the next cycle pulse width command for one of the switches relative to a rising edge of a previous cycle pulse width command for the one of the switches.