DC-DC Converter Switching Circuit for High-Voltage Bus Discharge
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Solution Overview
Problem
High-voltage electric power distribution systems in vehicles lack an effective discharge path for high-voltage electric power under certain circumstances, such as faults or short circuits in the low-voltage electric power distribution center, which can lead to system instability and potential damage.
Innovation Solution
A topology that includes a high-voltage bus electrically connected to a DC-DC electric power converter with a high-voltage switching circuit, transformer, and low-voltage rectifier, controlled by a controller that can operate the switches in linear and pulsewidth-modulated modes to discharge high-voltage electric power to a low-voltage DC load, providing a redundant discharge path through the DC-DC converter when the primary discharge path is unavailable.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the primary discharge path through the low-voltage electric power distribution center is used, then the system operates normally under standard conditions, but the system becomes unstable and vulnerable to damage when faults or short circuits occur in the low-voltage distribution center
Solution Approach 1:
The discharge path is segmented into multiple independent routes: the primary discharge path through the low-voltage electric power distribution center and the secondary discharge path through the DC-DC electric power converter. This segmentation allows the system to isolate faults in one path without affecting the other, thereby improving reliability while maintaining manageable complexity through modular design.
Solution Approach 2:
The secondary discharge path through the DC-DC electric power converter is prepared in advance as a protective measure. When faults or short circuits occur in the low-voltage distribution center, this pre-configured alternative path immediately becomes available to discharge high-voltage electric power, preventing system instability and damage before they can propagate.
2Reliability
If a secondary discharge path through the DC-DC converter is added, then the system gains redundancy and stability under fault conditions, but the device complexity and control requirements increase
Solution Approach 1:
The switching circuit employs dynamic control with two distinct operational modes: linear mode for the first switch and pulsewidth-modulated mode for the second switch. The controller dynamically adjusts the duty cycle of the pulsewidth-modulated switch based on real-time magnitude of electric current feedback, allowing the system to adapt to varying fault conditions and optimize discharge performance while managing control complexity through structured mode switching.
Solution Approach 2:
A magnitude of electric current sensor provides real-time feedback on the current flowing through the high-voltage power bus. This feedback is fed to the controller, which uses it to dynamically adjust the duty cycle of the pulsewidth-modulated switch, ensuring stable and efficient discharge operation while preventing excessive current that could damage components.
3Productivity
If the first switch operates in linear mode and the second switch operates in pulsewidth-modulated mode, then stable and efficient discharge is achieved, but the control system complexity increases
Solution Approach 1:
Different operational qualities are applied to different switches based on their specific roles in the discharge path. The first switch operates in linear mode to provide stable voltage control and protectiveness, while the second switch operates in pulsewidth-modulated mode to provide efficient and adjustable power discharge. This localized optimization of switch operating modes achieves both stability and efficiency without requiring all switches to operate in the same complex mode.
Solution Approach 2:
The controller changes the operational parameters of the switches based on the discharge requirements. The first switch maintains a relatively simple linear operating state for stability, while the second switch utilizes pulsewidth-modulated operation with dynamically adjusted duty cycle based on current magnitude feedback. This parameter differentiation optimizes discharge efficiency while managing control complexity through structured parameter management.
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 ensures stable and efficient discharge of high-voltage electric power to a low-voltage DC load, even when the primary discharge path is faulty, thereby preventing system instability and protecting the vehicle's electrical components.
Implementation Method 1
a transformer, and a low-voltage rectifier
Implementation Method 2
a low-voltage rectifier
Data Source
AI summary
A topology for electric power distribution in a vehicle includes a high-voltage bus connected to a DC-DC electric power converter that is connected to a low-voltage DC load. The DC-DC electric power converter includes a high-voltage switching circuit, a transformer, and a low-voltage rectifier. The high-voltage switching circuit includes first and second switches arranged in series between positive and negative legs of the high-voltage electric power bus at a first node that connects to a leg of an inductor of the transformer. A controller receives a command to discharge the high-voltage electric power bus, and in response, controls a first gate circuit to operate a first switch in a linear mode, and controls a second gate circuit to operate a second switch in a pulsewidth-modulated mode. A duty cycle for the pulsewidth-modulated operation of the second switch is determined based upon the magnitude of electric current.