Stiff Current Power Converter Topologies for Motor Drive Packaging

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Solution Overview

Problem

Existing motor drives based on stiff voltage sources are prone to short-circuit non-conforming events, which can damage electronic circuits due to rapid current increases when the voltage remains constant, and lack flexible packaging options for efficient component placement.

Innovation Solution

A power converter topology that delivers a stiff current source using a driver with power electronics, capacitors, and an inductor to regulate current, allowing for flexible packaging and preventing transients, and a pseudo current source topology formed from a stiff voltage source, capacitor, and inductor to maintain a constant current to the load.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a stiff voltage source topology is used to power motor drives, then the topology is simple and control requirements are simple, but short-circuit currents can rapidly increase and damage electronic circuits

Engineering Contradiction:

Improvetopology complexityVSAvoidshort-circuit protection

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent changes the fundamental parameter of the power source from constant voltage to constant current. The current source inverter uses a stiff current supply instead of a stiff voltage supply, fundamentally altering how the system handles load variations and short-circuit conditions. This parameter change eliminates the short-circuit current problem while maintaining system functionality.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the harmful effect of rapid current increase during short-circuits into a beneficial feature. By using a stiff current source, the system naturally limits current to a controlled level even during short-circuit conditions, transforming what would be a dangerous uncontrolled current surge into a protected, controlled current flow that prevents damage to electronic circuits.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Stability of the object's composition

If a stiff voltage source topology is used, then the voltage remains constant independent of load demands, but the current can rapidly increase forming a short circuit

Engineering Contradiction:

Improvevoltage stabilityVSAvoidshort-circuit current

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The patent changes the controlled parameter from voltage to current. Instead of maintaining constant voltage and allowing current to vary freely (which causes short-circuit hazards), the system maintains constant current while allowing voltage to vary. This parameter swap eliminates the harmful short-circuit current effect while providing stable power delivery to the motor drive.

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If traditional voltage source topologies are used, then the system operates simply, but flexible packaging options are limited for efficient component placement

Engineering Contradiction:

Improvesystem operation simplicityVSAvoidpackaging flexibility

Core Design Contradiction:

Ease of operationVSAdaptability or versatility

Solution Approach 1:

The patent segments the power converter into distinct functional modules: a stiff current source module, a DC-DC converter module, and an inverter module. This modular segmentation allows each module to be independently designed, packaged, and positioned, providing flexible packaging options for efficient component placement while maintaining the simplicity of operation through standardized interfaces and functions.

Inventive Principle:

Principle #1Segmentation

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

The solution effectively prevents damage from short-circuit transients and allows for efficient packaging of components, providing a controllable and stiff current supply to electric loads, enhancing reliability and flexibility in motor drive systems.

Implementation Method 1

an inductor coupled in series with the stiff voltage source and further in series with the first capacitor to hold a current delivered to the electric load stiff

Methodology Applied

Scientific EffectElectromagnetic Induction: Electromagnetic Induction

Implementation Method 2

at least one capacitor coupled to the load and to the power electronics to prevent transients from damaging the current source power converter

Methodology Applied

Scientific EffectCapacitance: Capacitance

Data Source

PatentUS7339345B2Power converter topologies for better traction drive packaging

Publication Date: 2008.03.04 FORD GLOBAL TECH LLC

AI summary

At least three alternative stiff current supply power converter topologies provide fixed current to a respective electric load such as a motor, or a non-inductive electric load using either a current source or a pseudo current source. The stiff current power converter topologies reduce the size of passive components within each of the topologies, thus reducing the overall packaging of each of the components and subsystems formed by each of the components. Each of the topologies have a stiff current source, a driver having power electronics formed therein to drive the associated electric load, wherein the stiff current source and the driver operate to deliver a stiff but controllable current to the electric load.