Power Controller Input Current Estimation via Primary Side

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Solution Overview

Problem

Conventional switching power converters require direct sensing of input current, which increases system costs and size due to additional components and causes power losses, while also being necessary for maintaining proper operation of dimmer switches in LED lamp systems.

Innovation Solution

A power controller estimates the average input current without direct sensing by calculating it based on the target peak primary side current and impedance of a sense resistor, reducing system costs and size, and maintaining dimmer switch operation by regulating the input current.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If direct sensing of input current is used, then accurate input current measurement is achieved, but system cost and size increase due to additional components

Engineering Contradiction:

Improveinput current measurement accuracyVSAvoidsystem cost and size

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses the primary side current as an intermediary parameter to indirectly estimate the input current. Instead of directly measuring input current with a sense resistor or transformer, the system measures the primary side current through an existing sense resistor and uses the known relationship between primary and input current to calculate the input current value. This intermediary approach eliminates the need for additional direct sensing components.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the physical direct current sensing mechanism (sense resistor or current transformer in the input path) with a computational approach. The system substitutes hardware-based direct measurement with a mathematical estimation method that uses the primary side current measurement and the relationship equation to derive input current, thereby eliminating the need for additional sensing components in the input path.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If direct sensing components are added, then input current can be measured accurately, but power losses increase through the sensing components

Engineering Contradiction:

Improveinput current measurement accuracyVSAvoidpower losses through sensing components

Core Design Contradiction:

Measurement precisionVSLoss of energy

Solution Approach 1:

The patent uses primary side current measurement as an intermediary that does not introduce additional power losses into the input path. By measuring the primary side current through an existing sense resistor and calculating the input current based on the known relationship, the system avoids inserting additional sensing components that would cause voltage drops and power losses in the input current path.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If input current is directly sensed, then dimmer switch operation can be maintained, but system complexity and cost increase

Engineering Contradiction:

Improvedimmer switch operationVSAvoidsystem complexity and cost

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent uses the primary side current measurement and the relationship between primary and input current as an intermediary method to maintain dimmer switch operation. The controller estimates the input current value using the primary side current and known parameters, which is then used to control the power converter to provide sufficient current for the dimmer while minimizing power loss, without requiring direct input current sensing components.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 method reduces system material and size costs while minimizing power losses and ensures proper operation of dimmer switches by accurately estimating and regulating the input current, achieving high power factor and low total harmonic distortion.

Implementation Method 1

an impedance of a sense resistor for sensing the primary side current of the power converter

Methodology Applied

Scientific EffectOhm's Law: Ohm's Law

Implementation Method 2

The controller measures the voltage drop across a voltage divider. In one embodiment, the voltage divider includes the sense resistor and an additional resistor for measuring the impedance of the sense resistor

Methodology Applied

Scientific EffectVoltage division: Ohm's Law

Data Source

PatentUS9071147B2Average input current estimation based on primary side current sense

Publication Date: 2015.06.30 DIALOG SEMICONDUCTOR INC

AI summary

The embodiments herein describe a power converter including a controller that estimates input current of the power converter. The controller estimates the input current without explicitly sensing the input current. The estimated input current can be used in various applications such as regulating power factor and total harmonic distortion as well as estimating current required to maintain proper operation of a dimmer switch in light emitting diode lamp systems.