Bidirectional DC/DC Converter for Emergency Load Lowering
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Solution Overview
Problem
Existing emergency systems for work machines like cranes and cable excavators are inadequate as they often require a separate backup energy source for safe load lowering, which is not always feasible due to insufficient kinetic energy from the primary energy source, especially when starting from a standstill.
Innovation Solution
A bidirectional DC/DC converter connects the high voltage and low voltage onboard networks, allowing energy flow in both directions, enabling the low voltage rechargeable battery to supply the high voltage network upon primary energy source failure, thus facilitating emergency load lowering without additional backup components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate backup energy source is provided in the high voltage onboard network for emergency load lowering, then emergency safety is improved, but device complexity and weight increase
Solution Approach 1:
The low voltage battery, originally designed solely for low voltage consumers, is made multi-functional by enabling it to also supply the high voltage onboard network during emergencies through the bidirectional DC/DC converter. This eliminates the need for a separate backup energy source in the high voltage network while maintaining emergency safety.
Solution Approach 2:
The patent merges the backup energy supply function into the existing low voltage battery system rather than adding a separate backup system. The bidirectional DC/DC converter enables energy transfer from the low voltage battery to the high voltage network, combining multiple functions into a single integrated system.
2Reliability
If a sufficiently dimensioned rechargeable battery is provided in the high voltage onboard network for emergency lowering, then emergency capability is improved, but weight and device complexity increase
Solution Approach 1:
The low voltage battery serves dual purposes: supplying low voltage consumers during normal operation and providing emergency energy to the high voltage network when needed. This multi-functionality eliminates the need for additional emergency batteries, reducing overall system weight.
Solution Approach 2:
The existing low voltage battery, already present in the system for other purposes, is made to serve the additional function of emergency energy supply. The battery essentially serves itself by providing energy across different voltage networks through the bidirectional DC/DC converter.
3Use of energy by moving object
If kinetic energy from the primary energy source is used for emergency lowering, then energy availability is improved, but reliability deteriorates when the machine is stationary
Solution Approach 1:
Energy is stored in advance in the low voltage battery during normal operation. This preliminary energy storage ensures that when an emergency occurs and the machine is stationary with insufficient kinetic energy, the battery can immediately provide the necessary energy for safe load lowering.
Solution Approach 2:
The bidirectional DC/DC converter acts as an intermediary that enables energy transfer from the low voltage battery to the high voltage network. This mediator allows the battery to supplement the primary energy source during emergencies, ensuring reliable energy availability regardless of the machine's motion state.
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 safe and controlled emergency load lowering by utilizing the energy stored in the low voltage battery, reducing the need for separate backup systems and ensuring energy availability even when the machine is stationary, thereby enhancing operational safety and efficiency.
Implementation Method 1
The high voltage onboard network and the low voltage onboard network are connected via a bidirectional DC/DC converter to allow an energy flow from the high voltage onboard network in the direction of the low voltage onboard network and moreover to allow an energy flow from the low voltage onboard network in the direction of the high voltage onboard network.
Data Source
AI summary
A device for emergency supply of a high voltage onboard network, in particular for the emergency load lowering of a work machine such as a crane or a cable excavator, comprising a high voltage onboard network having an electrical drive unit and a primary DC energy source for supplying the electrical drive unit with energy; a low voltage onboard network, preferably a 12 V, 24 V, or 48 V onboard network, having a low voltage rechargeable battery for taking up and outputting energy, wherein the high voltage onboard network and the low voltage onboard network are connected via a DC/DC converter to allow an energy flow from the high voltage onboard network in the direction of the low voltage onboard network. The DC/DC converter is preferably a bidirectional DC/DC converter to permit an energy flow from the low voltage onboard network in the direction of the high voltage onboard network.