Power Converter Controller Di/dt Prediction for Zero Crossing

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Solution Overview

Problem

In DC-DC converter systems, the double arm drive period is difficult to predict accurately due to ripple components in reactor current, leading to increased gate interference and energy losses during zero crossing events.

Innovation Solution

A power conversion apparatus that includes a pair of switching elements connected in series, a coil, and a controller that calculates the time rate of change of the coil current to switch between single arm drive and double arm drive modes based on voltage and inductance, allowing for more precise control of the double arm drive period.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If double arm drive is performed during zero crossing to ensure proper current transition, then reliability of current switching is improved, but gate interference and energy losses increase due to extended double arm drive period

Engineering Contradiction:

Improvecurrent switching reliabilityVSAvoidgate interference loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent changes the control parameter from fixed double arm drive timing to dynamically adjusted timing based on predicted current zero crossing points. By calculating di/dt and predicting when current will reach zero, the system optimizes the double arm drive period duration to be just long enough for reliable switching without excessive gate interference losses.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent performs preliminary calculation of the time rate of change of current (di/dt) before the zero crossing event occurs. This allows the controller to predict the exact timing of zero crossing and prepare the optimal double arm drive period in advance, ensuring reliable current transition while minimizing energy losses.

Inventive Principle:

Principle #10Preliminary action

2Loss of energy

If double arm drive period is shortened to reduce gate interference, then energy losses are reduced, but accuracy of zero crossing timing prediction deteriorates due to ripple components in reactor current

Engineering Contradiction:

Improvegate interference lossVSAvoidzero crossing timing prediction accuracy

Core Design Contradiction:

Loss of energyVSMeasurement precision

Solution Approach 1:

The patent introduces di/dt (time rate of change of current) as an intermediary parameter to predict zero crossing timing. Instead of directly measuring the noisy current signal with ripple components, the system calculates the rate of change from voltage and inductance, providing a cleaner prediction signal that maintains accuracy while enabling shorter double arm drive periods.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces direct current measurement (which is affected by ripple noise) with a calculation-based approach using di/dt prediction. This substitution of measurement method eliminates the interference from ripple components and achieves more accurate zero crossing timing prediction.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Device complexity

If fixed control method is used for simplicity, then device complexity is reduced, but double arm drive period cannot be optimized leading to increased energy losses

Engineering Contradiction:

Improvecontrol system complexityVSAvoidgate interference loss

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The patent implements a self-optimizing control system that automatically calculates di/dt and determines the optimal double arm drive period based on real-time operating conditions. The controller adapts to different voltage and inductance conditions without requiring manual tuning, achieving energy optimization while maintaining relatively simple implementation through self-adjustment.

Inventive Principle:

Principle #25Self-service

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enables a shorter double arm drive period, reducing gate interference and energy losses by improving the accuracy of zero crossing timing prediction.

Implementation Method 1

a controller that calculates, based on a voltage between the higher potential side terminal and the lower potential side terminal and an inductance of the coil, a time rate of change of a current value of a current flowing through the coil

Methodology Applied

Scientific EffectFaraday's Law of Electromagnetic Induction: Electromagnetic Induction

Data Source

PatentUS9742337B2Power conversion apparatus

Publication Date: 2017.08.22 TOYOTA JIDOSHA KK

AI summary

A power conversion apparatus includes a pair of switching elements that are connected in series between a higher potential side terminal and a lower potential side terminal to form upper and lower arms; a coil whose end is connected between the pair of switching elements; and a controller that calculates, based on a voltage between the higher potential side terminal and the lower potential side terminal and an inductance of the coil, a time rate of change of a current value of a current flowing through the coil, and switches, based on the calculated time rate of change of the current value, between a single arm drive mode in which only one of the pair of switching elements is driven to be turned on/off and a double arm drive mode in which the pair of switching elements are driven to be turned on/off in opposite phase.