EV Charging Control via PFC Current Limiting
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Solution Overview
Problem
Existing charging methods for electric vehicles often result in external charging device shut-downs due to overcurrent, and fail to maximize battery charging efficiency as they limit the charging current to prevent such shut-downs.
Innovation Solution
A charging control method and system that utilizes a power factor correction circuit (PFC) and DC/DC converter, where a PFC controller receives a control pilot signal to restrict the allowable current value, derives an output current command value by applying it to a proportional-integral controller, and adjusts the charging current to prevent overcurrent while optimizing battery charging efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the charging current is increased to improve battery charging efficiency, then the charging speed increases, but the external charging device may shut down due to overcurrent
Solution Approach 1:
The patent implements a feedback control mechanism where the controller continuously monitors the charging current and compares it against the maximum allowable current value obtained from the charging device. When the current approaches the limit, the controller adjusts the charging rate to prevent overcurrent conditions, thereby maintaining both high charging speed and device stability through closed-loop control
Solution Approach 2:
The patent applies dynamic current adjustment by varying the charging current in real-time based on the battery's state of charge and the charging device's capacity. The controller dynamically modifies the charging profile to optimize charging speed while ensuring the current never exceeds the maximum allowable value, thus preventing device shut-down
2Reliability
If the charging current is limited to prevent charging device shut-down, then the device stability is maintained, but the battery charging efficiency decreases
Solution Approach 1:
The patent changes the charging parameters dynamically by adjusting the current magnitude, voltage levels, and charging profile based on real-time conditions. By modifying these parameters within safe operational limits, the system maintains device stability while maximizing charging efficiency through optimized current utilization throughout the charging process
Solution Approach 2:
The patent applies partial action by delivering charging current at levels that are sufficient to achieve high charging efficiency without reaching the excessive threshold that would cause device shut-down. The controller precisely controls the current to be just below the maximum allowable value, optimizing the balance between charging speed and device protection
3Adaptability or versatility
If multiple vehicles are charged simultaneously using a single charging device, then the charging capacity utilization increases, but the current per vehicle must be reduced to prevent overcurrent
Solution Approach 1:
The patent implements dynamic current allocation that automatically adjusts the charging current for each vehicle based on the number of connected vehicles and the total charging device capacity. When multiple vehicles are connected, the controller dynamically redistributes the available current to ensure fair allocation while maintaining optimal charging speed for each battery, preventing overcurrent conditions
Solution Approach 2:
The patent creates a universal charging control system that can handle multiple vehicles simultaneously with different battery capacities and charging requirements. The controller universally applies the current management algorithm across all connected vehicles, adapting the charging profile for each vehicle while ensuring the total current remains within the charging device's maximum capacity
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
Prevents external charging device shut-downs by limiting the input current to a maximum allowable value, reduces charging time, and achieves stable and efficient battery charging by maximizing the output current value close to the allowable limit.
Implementation Method 1
a power factor correction circuit (PFC) and a direct current-direct current (DC/DC) converter
Data Source
AI summary
A charging control method for an electric vehicle is provided. The method uses a vehicle charging device that includes a power factor correction circuit (PFC) and a DC/DC converter. The method includes receiving, by a PFC controller, a control pilot (CP) signal from an external charging device and restricting by the PFC controller an allowable current value derived by analyzing the CP signal to a maximum current value that is to be applied to the PFC. The PFC controller then derives an output current command value of the DC/DC converter by applying an output value of a voltage controller of the PFC to the allowable current value. A DC/DC converter controller then charges a battery using the output current command value of the DC/DC converter.