Charging Device Switching Resistor for Capacitor Discharge
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Solution Overview
Problem
The existing charging systems for electric vehicles face inefficiencies due to power losses from discharging resistors used to manage residual voltage in capacitors, which compromise both electromagnetic compatibility (EMC) behavior and charging efficiency.
Innovation Solution
A charging device with a switching mechanism and additional resistors is introduced to assist in the discharging of capacitors, allowing for the relocation of discharging resistors from the vehicle to the charging device, and a measuring circuit to detect switch defects, enabling efficient discharging and reducing power losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If discharging resistors are used to manage residual voltage in capacitors, then EMC behavior is improved, but power losses increase and charging efficiency decreases
Solution Approach 1:
The patent applies dynamics by making the discharging resistor switchable - the resistor is only connected to the capacitor during the discharging phase after charging completion, not continuously. This dynamic switching allows the system to achieve rapid voltage drop (improving EMC behavior) while avoiding continuous power loss during normal charging operation.
Solution Approach 2:
The discharging resistor is activated periodically - specifically after the charging process is completed - rather than operating continuously. This periodic activation ensures that the resistor only draws power when needed for safety discharging, thereby reducing overall energy losses while maintaining EMC compliance.
2Loss of energy
If the resistor value is increased to reduce power losses, then charging efficiency is improved, but the voltage drop rate becomes too slow to meet standard requirements
Solution Approach 1:
The system dynamically switches the resistor into the circuit only when needed for discharging. By using a higher resistance value that would be unsuitable for continuous operation, the patent achieves both reduced power loss (when switched off) and sufficient voltage drop rate (when switched on during discharging phase).
Solution Approach 2:
The charging process is allowed to complete fully before activating the discharging resistor. This preliminary completion of charging ensures that the resistor only operates during the discharging phase, allowing the use of higher resistance values that would otherwise cause excessive power loss during charging.
3Reliability
If the capacitor value is increased to improve EMC behavior, then electromagnetic compatibility is improved, but the time constant increases and voltage drop becomes slower
Solution Approach 1:
By dynamically switching the resistor into the circuit during the discharging phase, the patent can use larger capacitor values for better EMC filtering without being constrained by the time constant issue. The switched resistor provides an additional discharge path that accelerates voltage drop despite the larger capacitance.
Solution Approach 2:
The patent combines the capacitor's natural discharge function with the additional discharging resistor to create a hybrid discharge mechanism. This combination allows larger capacitor values to be used for improved EMC behavior while the resistor compensates for the slower discharge rate that would otherwise result from the larger time constant.
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 enhances EMC behavior, reduces power losses, and allows for faster discharging of residual voltages, improving the overall efficiency and reliability of the charging process while simplifying defect detection in the charging system.
Implementation Method 1
a charging device for charging an at least partially electrically operated vehicle is proposed which comprises at least one electrical component (e.g. ohmic resistor) and a switching device (e.g. opto-triac, relay)
Data Source
AI summary
An embodiment of the invention relates to a charging device for charging an at least partially electrically operated vehicle. The charging device is formed with at least one electrical component and a switching device. The at least one electrical component and the switching device are arranged in the charging device in such a way that when the charging device is connected to a vehicle a circuit is produced for assisting the discharging of at least one capacitor provided on the vehicle side, the capacitor being openable or closable via the switching device.