EV Charging Device Control Mode Switching for Efficiency
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Solution Overview
Problem
Existing charging devices for electromotive vehicles face inefficiencies in DC-DC conversion due to power losses and potential excessive current issues during external charging, particularly when the upper arm element of the DC-DC converter is kept in an on state without proper control conditions.
Innovation Solution
A charging device with a control system that selectively switches between two control modes based on the state of external charging, using a first electric power converter to convert AC voltage to DC voltage and a second converter to manage charging current, with on/off control of switching elements to optimize charging efficiency and prevent excessive current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the upper arm element of the DC-DC converter is kept in an on state to increase charging efficiency, then charging efficiency of the converter is improved, but excessive current may occur or efficiency of other elements may decrease
Solution Approach 1:
The patent applies dynamics by making the switching element's state changeable rather than fixed. The control device dynamically adjusts the switching element between on-state and off-state based on real-time comparison between battery voltage and rectified voltage, enabling the system to adapt to varying charging conditions and avoid excessive current while maintaining high efficiency
2Productivity
If DC-DC conversion operation is performed to charge the electrical storage device, then charging can be performed, but power loss occurs due to switching element resistance and inductor losses
Solution Approach 1:
The patent extracts the DC-DC conversion step from the charging path by directly connecting the rectified voltage to the battery when rectified voltage exceeds battery voltage. This eliminates the intermediate DC-DC conversion process and its associated power losses from switching elements and inductors, achieving lossless charging under appropriate conditions
3Ease of operation
If the switching element is frequently switched on and off to control charging current, then charging current can be regulated, but power loss increases due to switching element resistance
Solution Approach 1:
The patent uses periodic action through controlled switching of the switching element based on voltage comparison. The element is switched on when rectified voltage exceeds battery voltage and turned off when it falls below, creating a periodic switching pattern that regulates charging current while minimizing unnecessary switching operations and associated power losses
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 approach enhances the charging efficiency of electrical storage devices in electromotive vehicles by adapting control modes based on charging conditions, reducing power losses and excessive current risks, thereby improving overall charging performance.
Implementation Method 1
a first electric power converter that converts an alternating-current voltage, supplied from an external power supply, to a direct-current voltage higher than a peak voltage of the alternating-current voltage
Implementation Method 2
The first electric power converter converts an alternating-current voltage, supplied from an external power supply, to a direct-current voltage higher than a peak voltage of the alternating-current voltage
Implementation Method 3
a second electric power converter that, during external charging for charging the electrical storage device by the external power supply, converts direct-current electric power between the first power supply line and a second power supply line that is electrically connected to a positive electrode of the electrical storage device
Implementation Method 4
The second electric power converter includes a first switching element that is electrically connected between a first node and the first power supply line and a first inductor that is electrically connected between the first node and the second power supply line
Data Source
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AI summary
An AC-DC converter (250) converts an alternating-current voltage (vac), supplied from an external power supply (500), to a direct-current voltage higher than a peak voltage of the alternating-current voltage, and outputs the direct-current voltage to a first power supply line (PL1). In a normal control mode, a DC-DC converter (210) steps down a voltage of the power supply line (PL1) through on/off control over a switching element (Ql) to charge a main battery (10). On the other hand, in an upper arm ON control mode, the DC-DC converter (210) charge the main battery (10) while the switching element (Ql) is kept in an on state. On the basis of a state of external charging, a control device (300) applies the upper arm ON control mode when a condition that upper arm ON control is applicable is satisfied, and applies the normal control mode when the condition is not satisfied.