Power Source Device With Narrow DC Link Voltage
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Solution Overview
Problem
Existing power source devices for electric vehicles face efficiency issues when charging main batteries from commercial AC power sources, particularly due to wide operational voltage ranges that reduce the efficiency of insulated DC-DC converters and increase costs.
Innovation Solution
A power source device comprising an insulated AC-DC converter and a bidirectional DC-DC converter, which narrows the voltage range of the DC link voltage, allowing for efficient charging and power supply to accessory loads while maintaining high efficiency across varying battery voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the operational voltage range of the main battery is set to be wide to enable charging at maximum power, then the charging speed is improved, but the efficiency of the insulated DC-DC converter decreases
Solution Approach 1:
The power conversion system is divided into two separate converters: an insulated AC-DC converter for rectifying AC power to DC link voltage, and a bidirectional DC-DC converter for managing battery charging/discharging. This segmentation allows each converter to operate within optimized voltage ranges, maintaining high efficiency even when the battery operates across a wide voltage range for fast charging.
Solution Approach 2:
A DC link voltage is introduced as an intermediate stage between the AC power source and the battery. The insulated AC-DC converter generates this DC link voltage from AC input, and the bidirectional DC-DC converter uses it as its input to charge the battery. This intermediary voltage level allows both converters to operate efficiently within their respective optimal voltage ranges, decoupling the efficiency issue from the battery's wide operational voltage range.
2Power
If the current capacity of the resonance DC-DC converter is increased to enable fast charging at low battery voltage, then the charging power is improved, but the device complexity increases
Solution Approach 1:
The patent merges the AC-DC conversion function and the DC-DC conversion function into a unified power source device with a common control system. The insulated AC-DC converter and bidirectional DC-DC converter share the same housing and control unit, reducing overall device complexity while enabling high charging power through coordinated operation of both converters.
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
The solution enables high-efficiency charging of main batteries and power supply to loads with reduced converter losses and costs, even when the main battery voltage range is wide, by maintaining a narrower voltage range for the DC link voltage.
Implementation Method 1
an insulated AC-DC converter which receives an AC voltage to output a link voltage
Implementation Method 2
a bidirectional DC-DC converter which receives the link voltage to charge a battery, and receives the charged power to output the link voltage
Data Source
AI summary
Provided is a power source device having a high efficiency. A power source device 1 includes an insulated AC-DC converter 2 which receives a voltage of an AC power source 10 and outputs a link voltage Vlink, a bidirectional DC-DC converter 3 which receives the link voltage Vlink to charge a main battery 5, an insulated DC-DC converter 4 which receives the link voltage Vlink to supply power to a load 7, an operation mode in which the power is supplied from the AC power source 10 to the main battery 5, and an operation mode in which the power is supplied from the main battery 5 to the load 7.