DC/DC Converter Bus Capacitor Discharge Without Extra Resistors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for active discharging of bus capacitors in electric vehicles are costly due to the need for additional switches and resistors, which also pose safety risks and inefficiencies.
Innovation Solution
A bus capacitor discharging method utilizing a DC/DC converter with a chopper unit, transformer, and rectifier unit, where the controller short-circuits the transformer's secondary side and closes a loop between the bus capacitor and the transformer's primary side, eliminating the need for additional switches and resistors, thereby reducing costs and ensuring safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a switch and a resistor are added between positive bus and negative bus for active discharging, then the bus capacitor can be discharged quickly to ensure safety, but the cost increases due to additional components
Solution Approach 1:
The patent makes the existing DC/DC converter components (chopper unit and rectifier unit) serve the additional function of bus capacitor discharging. The chopper unit's switch tube and inductor, along with the rectifier unit's diode, form a discharge circuit that utilizes existing components rather than requiring dedicated discharging components, thereby reducing cost while maintaining safety.
Solution Approach 2:
The existing DC/DC converter components are designed to perform multiple functions: the chopper unit and rectifier unit not only perform their original power conversion functions but also serve as the active discharging circuit for the bus capacitor. This multi-functionality eliminates the need for separate discharging components, reducing overall system cost.
2Productivity
If a switch and a resistor are added for active discharging, then the discharging function is achieved, but the device complexity increases
Solution Approach 1:
The DC/DC converter's existing components (chopper unit with switch tube and inductor, rectifier unit with diode) are made to serve the discharging function themselves. By controlling the switch tube to conduct and forming a closed loop with the bus capacitor, the system achieves active discharging without requiring additional dedicated discharging components.
Solution Approach 2:
The discharging circuit is merged with the existing DC/DC converter circuitry. The chopper unit's switch tube and inductor, combined with the rectifier unit's diode, are integrated to form the discharge path, combining the power conversion and discharging functions into a single unified circuit structure.
3Device complexity
If the rectifier unit is not controlled during discharging, then the circuit is simpler, but excessively high output voltage may occur causing safety issues
Solution Approach 1:
The controller monitors the discharging process and controls the rectifier unit's diode based on the operational state. When the switch tube conducts during discharging, the controller ensures the diode is in the correct state to prevent excessive voltage. This feedback control mechanism maintains safety while managing the complexity of the control system.
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 method effectively discharges bus capacitors at low cost and high security, avoiding excessive output voltages and ensuring reliable energy consumption without the need for additional components.
Implementation Method 1
a transformer, and a rectifier unit... a primary side of the transformer, a secondary side of the transformer
Implementation Method 2
energy on the bus capacitor may be consumed by the resistor... form a closed discharge loop
Data Source
AI summary
This application discloses a bus capacitor discharging method and a related device thereof. The discharging method is applicable to a DC/DC converter, and the DC/DC converter includes a chopper unit, a transformer, and a rectifier unit. A bus capacitor is coupled to the chopper unit, the chopper unit is coupled to a primary side of the transformer, a secondary side of the transformer is coupled to the rectifier unit, and the chopper unit and the rectifier unit are both coupled to a controller. During specific implementation, when determining to discharge the bus capacitor, the controller may control the rectifier unit to short-circuit the secondary side of the transformer, and control the chopper unit to close a loop formed between the bus capacitor and the primary side of the transformer.