Half-Bridge Capacitor Discharge Using Linear-Mode Power Switches
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Solution Overview
Problem
Existing electric circuit arrangements in vehicles, particularly those used in electromobility, face challenges in efficiently and economically discharging energy accumulators like intermediate circuit capacitors, which often require large and expensive discharge resistors that consume space and generate heat.
Innovation Solution
A discharge control circuit is introduced to manage the power switching elements into a linear operation, using a separate discharge control circuit to generate discharge voltages, eliminating the need for additional components and reducing reliance on driver circuits, thereby allowing discharge through the half bridge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate discharge circuit with discharge resistors is used to discharge the energy accumulator, then the energy accumulator can be discharged safely, but the device complexity and cost increase significantly
Solution Approach 1:
The patent merges the discharge function with the existing half-bridge circuit by utilizing the power switching elements and driver circuits that are already present in the inverter. The driver circuits generate control voltages to operate the power switching elements in their linear region, enabling the half-bridge to function as a discharge path without requiring separate discharge components.
Solution Approach 2:
The power switching elements and driver circuits are designed to serve multiple functions: normal switching operation during inverter function and linear region operation during discharge function. This multi-functionality eliminates the need for dedicated discharge components while maintaining safe discharge capability.
2Reliability
If large discharge resistors are used to discharge the high-capacity energy accumulator, then the discharging can be achieved, but the resistors become large and expensive
Solution Approach 1:
The patent changes the operating parameters of the power switching elements from their normal switching state to linear region operation. By adjusting the control voltage from the driver circuits, the power switching elements operate in their linear region where they exhibit variable resistance characteristics, enabling discharge functionality without requiring large fixed-value discharge resistors.
3Reliability
If additional power semiconductors are added to create a dedicated discharge circuit, then the discharging function is improved, but the device complexity and design space consumption increase
Solution Approach 1:
The existing half-bridge circuit serves itself for discharge by utilizing its own power switching elements and driver circuits. The driver circuits generate appropriate control voltages to operate the power switching elements in linear region, enabling the circuit to perform discharge function without external assistance or additional components.
4Reliability
If traditional discharge resistors are used, then the energy accumulator can be discharged, but significant heat is generated causing heating issues
Solution Approach 1:
The patent changes the operating state of the power switching elements from fully conductive or fully off states to linear region operation. This parameter change allows for controlled resistance adjustment during discharge, enabling better heat management compared to fixed-value discharge resistors that operate at constant high power dissipation.
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 reduces costs, design space, and weight while avoiding component heating, providing a robust and economical solution for safe and efficient discharging of energy accumulators.
Implementation Method 1
the power switching elements each have a switchable section, the electric resistance of which can be adjusted by a control voltage of the power switching element which is imposed at a control input of the power switching element
Data Source
AI summary
An electric circuit arrangement includes at least one half bridge including two power switching elements, two driver circuits, and a discharge control circuit, wherein the half bridge is in parallel with an energy accumulator and each power switching element has a switchable section with an electric resistance that is adjustable by a control voltage at a control input of the power switching element, while in a normal operation of the power switching elements, the drivers circuits generates the control voltage at the control input of each power switching element, and, while in at least one discharge operation that discharges the energy accumulator, the discharge control circuit generates a discharge voltage as the control voltage as the control input of at least one of the power switching elements, the discharge voltage placing the at least one of the power switching elements in linear operation.