Bidirectional DC/DC Converter Capacitor Discharge Control
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Solution Overview
Problem
Conventional non-contact power supplying systems face instability when switching between power transmission and reception due to residual charges in capacitors, leading to unintended electrical current flow in inverters and converters.
Innovation Solution
A power conversion device with bidirectional DC/DC converters and semiconductor switches that control voltage step-down and step-up operations, along with a controller to manage switching between power transmission and reception, ensuring stable operation by safely discharging accumulated charges in intermediate capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If bidirectional switching between power transmission and reception is implemented, then power supply flexibility is improved, but system stability deteriorates due to residual charges in capacitors causing unintended current flow
Solution Approach 1:
The controller performs preliminary discharge of the intermediate capacitor before switching between power transmission and reception modes. By detecting the voltage across the intermediate capacitor and discharging it when voltage exceeds a threshold, the system eliminates residual charges that would otherwise cause unintended current flow and instability during mode transitions.
2Speed
If capacitor charges are not discharged during switching, then switching speed is improved, but harmful current flow increases causing operational instability
Solution Approach 1:
The controller rapidly discharges the intermediate capacitor by connecting it through a discharge path when voltage exceeds the threshold, quickly eliminating residual charges before the switching operation. This rapid discharge action allows the system to maintain fast switching speeds while preventing harmful current flow during mode transitions.
3Reliability
If intermediate capacitor voltage is monitored and controlled, then operational stability is improved, but device complexity increases due to additional control circuitry
Solution Approach 1:
The controller continuously monitors the voltage across the intermediate capacitor and uses this feedback information to determine when discharge is necessary. When the detected voltage exceeds a predetermined threshold, the controller activates the discharge path; when voltage is within acceptable range, normal operation proceeds. This feedback mechanism ensures operational stability with minimal additional control complexity.
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
Enables stable switching between power transmission and reception, preventing overvoltage and current issues, and reducing energy loss by efficiently transferring charges to a DC power source or battery, thus ensuring reliable non-contact power supplying.
Implementation Method 1
a coil for non-contact power supplying is provided at the center thereof
Implementation Method 2
a bidirectional non-contact power supplying technology in which power transmission and power reception can be switched
Data Source
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AI summary
A power conversion device comprises an inner coil which can transmit power between an external coil by coupling magnetically with the external coil, an inverter (4a, 4b) whose AC side is connected to the inner coil and power conversion can be performed between the AC side and a DC side and a bidirectional DC/DC converter (5a, 5b) which comprises an intermediate capacitor (8a, 8b), is connected to the DC side of the inverter (4a, 4b) and can perform power conversion bidirectionally between a DC power source (7a, 7b), which is connected to a side which is opposite to the side of the inverter (4a, 4b), and the inverter (4a, 4b), wherein in switching operation from power reception to power transmission where power reception operation is switched to power transmission operation, after control of discharging charges which are accumulated in the intermediate capacitor (8a, 8b) is performed, the power transmission operation is started.