Distributed Brake Resistances for Rapid Power Dissipation

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Solution Overview

Problem

The existing apparatus for converting electrical energy to heat in drive and high-voltage technology has a long time delay between activating the braking controller and effectively converting real power to heat, making it unreliable for fault exclusion in converters.

Innovation Solution

The braking resistance is split into multiple individual resistances within bipolar submodules, each with an energy store and a controllable braking power semiconductor, allowing for quick conversion of real power to heat by matching the dimensions of the energy store and resistance, and using cooling devices for efficient heat dissipation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single braking resistance is used in the DC voltage link circuit, then the device complexity is low, but the conversion time of real power to heat is too long to reliably exclude faults

Engineering Contradiction:

Improvefault exclusion reliabilityVSAvoidbraking controller structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The braking resistance is divided into multiple individual braking resistances (Rb1, Rb2, etc.), each associated with a bipolar submodule. This segmentation allows independent control of each resistance element through dedicated braking power semiconductors, enabling faster and more reliable fault exclusion by selectively activating only the required braking elements rather than relying on a single large braking resistance.

Inventive Principle:

Principle #1Segmentation

2Speed

If the braking resistance is split into multiple individual resistances with energy stores and controllable semiconductors, then the conversion speed of real power to heat improves, but the device complexity increases

Engineering Contradiction:

Improvepower conversion speedVSAvoidbraking controller components

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The braking system is segmented into multiple independent units, each with its own energy store and controllable semiconductor. This allows parallel operation of multiple braking channels, significantly increasing the power conversion speed to heat while distributing the complexity across modular components rather than requiring one large complex system.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Energy stores are pre-charged during normal operation of the bipolar submodules. When braking is required, the pre-charged energy stores are immediately discharged through the controllable braking power semiconductors and individual braking resistances, enabling instantaneous power conversion to heat without delay for system initialization.

Inventive Principle:

Principle #10Preliminary action

3Measurement precision

If controllable power semiconductor valves are used instead of mechanical switches, then the control precision and response time improve, but the device complexity and cost increase

Engineering Contradiction:

Improvecontrol precisionVSAvoidpower semiconductor circuit

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

Mechanical switches are replaced with controllable power semiconductor valves in the braking controller. This substitution eliminates mechanical wear and contact bounce issues, providing superior control precision and faster response times for activating the braking resistances. The power semiconductors can be controlled by simple electrical signals, reducing the overall system complexity despite the increased electronic component sophistication.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 solution enables rapid and reliable conversion of real power to heat, improving fault tolerance and scalability in drive and high-voltage applications by allowing energy to be dissipated quickly and efficiently.

Implementation Method 1

The braking resistance is then used to convert the excess real power which occurs in a situation such as this to heat

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Implementation Method 2

using cooling devices for efficient heat dissipation

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

using cooling devices for efficient heat dissipation

Methodology Applied

Scientific EffectConvection: Convection

Data Source

PatentUS8610384B2Converter with distributed brake resistances

Publication Date: 2013.12.17 SIEMENS ENERGY GLOBAL GMBH & CO KG

AI summary

A device converts electrical energy into heat in the field of drive voltage technology and/or high voltage technology. The device contains a brake resistance and at least one controllable brake power semiconductor for controlling the conversion, enabling a rapid and economical transformation of effective power into heat as required. To this end, the brake resistance contains a plurality of individual brake resistances that are each part of a bipolar submodule. The submodules are connected in series, form a submodule series connection, and at least partially contain an energy accumulator respectively connected in parallel to an associated individual brake resistance and a controllable brake power semiconductor, which allows the current flow over the respectively associated individual brake resistance in a brake position, and interrupts the current flow over the brake resistance in a normal operating position.