Intermediate Circuit Capacitor Series-Parallel Switching for Vehicle Charging

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Solution Overview

Problem

High-cost intermediate circuit capacitances designed for high voltages and inefficiencies in charging systems, particularly during three-phase charging, lead to significant power losses and increased component stress.

Innovation Solution

The intermediate circuit is configured with two capacitors that can be connected in parallel or series using changeover switches, bypassing the diode circuit in series configuration to minimize losses and diverting asymmetrical components through a diode circuit, allowing efficient voltage distribution and power handling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If intermediate circuit capacitances are designed for high voltages to handle three-phase charging, then the system can process higher rectified voltages, but the cost of components increases significantly

Engineering Contradiction:

Improverectified voltage handling capabilityVSAvoidcomponent cost

Core Design Contradiction:

PowerVSEase of manufacture

Solution Approach 1:

The patent divides the intermediate circuit capacitor into two separate capacitances connected in series. This segmentation allows each capacitor to be rated for a lower voltage than the total rectified voltage, reducing individual component costs while maintaining the ability to handle high voltages through the series combination.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the voltage rating parameter of the capacitors from high-voltage single-component design to lower-voltage multi-component design. By operating each capacitor at a fraction of the total voltage (through series connection), the system achieves the same power handling capability with less expensive components.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If a diode circuit is used to divert asymmetrical components during three-phase charging, then the system can handle asymmetrical loads, but power losses increase due to voltage drop across the diodes

Engineering Contradiction:

Improveasymmetrical component handling capabilityVSAvoidpower loss

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent extracts the asymmetrical component handling function from the main power conduction path by using the diode circuit solely for diverting asymmetrical components. The main power flow bypasses the diodes through the series capacitors, minimizing energy loss while maintaining the ability to handle asymmetrical loads.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The diode circuit acts as an intermediary that handles only the asymmetrical components rather than the full power load. By separating the asymmetrical current path from the main power path, the system maintains adaptability for asymmetrical loads while minimizing power losses in the diode circuit.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Power

If changeover switches are used to configure capacitors in series for high voltage, then high rectified voltages can be handled, but the complexity of the circuit increases

Engineering Contradiction:

Improverectified voltage handling capabilityVSAvoidcircuit configuration complexity

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The changeover switches serve multiple functions: they configure the capacitors in series for high-voltage operation, provide bypass paths for the diode circuit to minimize losses, and enable flexible switching between different operational modes. This multi-functionality reduces the need for separate dedicated components for each function.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 configuration reduces power losses and maintains efficient charging by distributing high rectified voltages across multiple capacitors, minimizing diode circuit losses and effectively handling asymmetrical components, thus lowering overall system costs and improving efficiency.

Implementation Method 1

intermediate circuit capacitances must be designed according to the higher voltage

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

the diode circuit enables a neutral conductor to be connected in order to be able to divert symmetrical components

Methodology Applied

Scientific EffectDiode rectification: Diode

Data Source

PatentUS11554680B2Intermediate circuit and vehicle-mounted charging circuit with intermediate circuit

Publication Date: 2023.01.17 SCHAEFFLER TECHNOLOGIES AG & CO KG

AI summary

An intermediate circuit is equipped with a first terminal connection, which includes a neutral conductor connection, and with a first and a second intermediate circuit capacitor and a diode circuit. The intermediate circuit has configuration switches which in a first state connect the intermediate circuit capacitors to one another in series and in a second state connect the intermediate circuit capacitors to one another in parallel. The configuration switches are each designed as changeover switches, which bypass the diode circuit in the first state, wherein the neutral conductor connection is connected to the diode circuit. A vehicle-based charging circuit, which includes the intermediate circuit and a rectifier circuit, is also described.