Vehicle Charging Circuit with Switchable DC/DC Converters
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Solution Overview
Problem
Existing vehicle charging systems face challenges in efficiently adapting to varying AC voltage connections, leading to inefficiencies and increased costs due to the need for semiconductor technologies that can handle high voltages across different regional configurations.
Innovation Solution
A vehicle-side charging circuit with adjustable DC/DC converters connected in parallel or series via a switch apparatus, combined with an active rectifier that includes power factor correction and harmonic filtering, allows for adaptation to different AC voltage configurations, reducing the operating voltage requirements for semiconductors and enabling cost-effective charging across multiple voltage networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single-phase or multiphase AC voltage connection is used to charge the vehicle, then the charging circuit must be adapted to different voltage configurations, but using high-voltage semiconductor technology to handle all configurations increases cost
Solution Approach 1:
The charging circuit is divided into multiple DC/DC converter units (first, second, third DC/DC converters) that can be independently controlled. Each converter handles a portion of the total power, allowing the system to adapt to different voltage configurations by activating appropriate numbers and arrangements of converters rather than requiring a single high-voltage semiconductor solution
Solution Approach 2:
The circuit employs switchable connections that dynamically reconfigure the DC/DC converters between series and parallel arrangements based on the detected AC voltage configuration. This dynamic adaptability allows the same hardware to efficiently handle both single-phase and multiphase connections without requiring expensive high-voltage semiconductors for all operating conditions
2Reliability
If DC/DC converters are connected in series to handle high rectified voltage from three-phase connection, then the operating voltage for each converter is reduced, but the circuit complexity increases due to switchable connections
Solution Approach 1:
The high-voltage handling task is segmented across multiple DC/DC converters connected in series. By dividing the total voltage burden among several converters, each converter operates at a lower, more manageable voltage level that is compatible with standard semiconductor cut-off voltages, improving reliability without requiring specialized high-voltage components
Solution Approach 2:
The switchable connection apparatus serves multiple functions: it configures converters in series for high-voltage three-phase connections, in parallel for single-phase connections, and can be controlled based on detected AC voltage parameters. This multi-functionality justifies the added complexity by enabling a single circuit design to handle diverse operating conditions
3Power
If DC/DC converters are connected in parallel for single-phase operation, then the current-carrying capacity is increased, but the circuit requires complex switching to adapt between series and parallel configurations
Solution Approach 1:
Multiple DC/DC converters are merged in parallel configuration during single-phase operation to combine their current-carrying capacities. This allows the charging circuit to handle the required power levels for single-phase charging by aggregating the output of individual converters, achieving high current capability without requiring any single converter to be oversized
Solution Approach 2:
The circuit dynamically reconfigures the connection topology of DC/DC converters based on the detected AC voltage configuration. For single-phase connections, converters are switched to parallel arrangement to maximize current capacity; for multiphase connections, they are switched to series arrangement for voltage compatibility. This dynamic adaptation optimizes performance for each operating mode
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 enables efficient charging by dividing or multiplying operating voltages and current-carrying capacities, allowing the use of less expensive semiconductor switches and reducing the need for high-voltage components, thus optimizing charging efficiency and cost-effectiveness across different AC voltage connections.
Implementation Method 1
a rectifier (20) connected to said AC voltage interface (10) by way of said AC voltage side (21), said rectifier (20) having a function of rectifying the voltage applied to said AC voltage interface (10)
Implementation Method 2
a plurality of DC-isolating DC/DC converters (30, 40, 50; 300, 400, 500) connected in parallel or in series with one another
Data Source
AI summary
A vehicle-side charging circuit includes an AC-voltage interface, a rectifier connected thereto and at least one first and one second DC-to-DC converter. The DC-to-DC converters are electrically isolating, and each have at least one intermediate circuit capacitor and at least one switch unit. The charging circuit also includes an on-board electrical system connection. The rectifier is connected to the on-board electrical system connection by way of the DC-to-DC converters. The charging circuit has a switch device which connects the DC-to-DC converters so as to be switchable between one another. In a first switching state, the switching device connects the two intermediate circuit capacitors and the switching units of the DC-to-DC converters in parallel and, in a second switching state, connects the intermediate circuit capacitors and the switch units in series.