Dual-Active-Bridge DC/DC Discharge for Hazardous DC Link Voltage
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Solution Overview
Problem
Transport climate control systems face challenges in safely dissipating energy below hazardous threshold levels without additional components, preventing uncontrolled discharges, and minimizing user exposure to potentially hazardous voltages.
Innovation Solution
The implementation of a DC/DC converter with a dual-active bridge topology that controls phase shift between source-side and load-side bridges to dissipate energy actively, using a transformer to discharge current and minimize current flow to the load, thereby avoiding the need for passive discharge components and ensuring safe energy dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If passive discharge (e.g., bleeding resistor) is used to dissipate residual energy, then energy dissipation is achieved, but uncontrolled discharge time occurs and static power dissipation increases
Solution Approach 1:
The patent employs an active discharge circuit that dynamically controls the discharge process of residual energy in the DC link, replacing static passive discharge components. The controller actively manages the discharge current flow through switching devices, enabling controlled and accelerated energy dissipation that reduces discharge time while preventing uncontrolled discharge.
Solution Approach 2:
The discharge circuit utilizes the existing DC link capacitor and switching devices to dissipate its own residual energy without requiring external passive discharge components. The system serves itself by using internal components (switching devices and controller) to actively discharge the DC link, eliminating the need for separate bleeding resistors and reducing overall system complexity.
2Loss of energy
If chopper circuit with heater is used to provide energy dissipation, then energy dissipation is achieved, but user exposure to hazardous voltage occurs
Solution Approach 1:
The patent introduces a controlled discharge path as an intermediary between the hazardous DC link and the external environment. The controller and switching devices create a safe intermediate circuit that directs residual current flow through controlled paths, preventing direct exposure to hazardous voltages while still achieving effective energy dissipation.
Solution Approach 2:
The patent replaces mechanical/chopper-based energy dissipation methods with an electronically controlled discharge circuit. Instead of using mechanical choppers and heaters that expose users to hazardous voltages, the system uses electronic switching devices and controller logic to manage energy dissipation, substituting mechanical control with electronic control for safer operation.
3Loss of energy
If additional components (e.g., bleeding resistor) are used for energy dissipation, then residual energy can be dissipated, but device complexity increases
Solution Approach 1:
The patent makes the switching devices serve multiple functions: they perform their primary power conversion function during normal operation and simultaneously serve as discharge switches for dissipating residual energy in the DC link. The controller also performs dual roles by managing both power conversion control and discharge timing. This multi-functionality eliminates the need for separate bleeding resistors and reduces overall system complexity.
Solution Approach 2:
The patent merges the discharge circuit functionality with the existing power conversion circuit components. The switching devices and controller that already exist in the power supply system are combined to perform both power conversion and energy dissipation functions, consolidating multiple functions into existing components rather than adding separate discharge circuitry.
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 allows for safe and controlled energy dissipation below hazardous levels, preventing uncontrolled discharges and user exposure, while actively managing energy transfer to minimize shock hazards and operational inefficiencies.
Implementation Method 1
discharging current from the source-side bridge across a transformer to the load-side bridge
Implementation Method 2
the energy may be dissipated as a switching loss while allowing a minimum amount of real power to the load side
Data Source
AI summary
Technologies for safely lowering a DC link voltage potential include detecting shut down of a system that is powered by the DC link energy storage system and initiating an operating mode to dissipate energy as a form of loss without utilizing an additional resistor, that is, dissipating the DC link internally to the enclosed power module.