Multi-Input EV Charging System Using Motor Coils for Voltage Boosting
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Solution Overview
Problem
Conventional charging systems for electric vehicles require large and expensive boosting converters to increase charging voltage from 400V to 800V, and there is a need to prevent relay fusing or cutting and neutral point capacitor damage during the charging process.
Innovation Solution
A multi-input charging system using a motor driving system with a controller that diagnoses relay failures and short-circuits relays to stabilize voltage levels, allowing external charging power to be boosted and applied to the battery without additional apparatus, using an inverter and motor coils to manage voltage levels and prevent overcurrent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a large-capacity boosting converter is used to boost charging voltage from 400V to 800V, then the charging voltage can be increased to meet battery requirements, but the system becomes very heavy, large, expensive, and difficult to include in the vehicle
Solution Approach 1:
The motor driving system is made multi-functional by enabling it to perform both motor driving and voltage boosting operations. The inverter and motor coils that originally serve only for motor control are now also used for boosting charging voltage, eliminating the need for a separate boosting converter and reducing system weight and complexity
Solution Approach 2:
The patent merges the voltage boosting function with the existing motor driving system by combining the inverter and motor coils into a single integrated boosting converter. This consolidation eliminates redundant components and reduces overall system weight and size while maintaining the required 800V charging capability
2Adaptability or versatility
If multiple relays are used to determine charging power paths according to voltage levels, then the system can handle various voltage inputs, but the risk of relay fusing or cutting increases during the charging process
Solution Approach 1:
The controller performs preliminary diagnosis of relay status before initiating charging operations. By checking whether relays are normally connected in advance and pre-charging the neutral point capacitor to match the incoming charging voltage, the system prevents relay fusing or cutting caused by voltage mismatches or overcurrent, thereby improving reliability while maintaining adaptability to various voltage inputs
3Stability of the object's composition
If a capacitor is added to the charging power input stage for voltage stabilization, then voltage stability improves, but the capacitor may be damaged during the charging process
Solution Approach 1:
The neutral point capacitor is pre-charged to a voltage level matching the incoming charging voltage before the charging power is applied to the input stage. This preliminary charging action prevents voltage shocks and overcurrent that would otherwise damage the capacitor, thereby maintaining voltage stability while improving capacitor durability
4Reliability
If relay diagnosis and pre-charging control are implemented, then relay and capacitor damage is prevented, but the charging process requires additional control steps
Solution Approach 1:
The controller leverages its existing multi-functionality to perform both motor control and charging management tasks. By integrating relay diagnosis and pre-charging control into the existing controller firmware, the system achieves improved reliability without adding hardware complexity, as the controller already handles multiple functions including inverter control and charging coordination
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 system enables stable battery charging with various voltage levels by diagnosing relay failures and pre-charging capacitors, preventing damage and ensuring efficient voltage boosting without additional cost or equipment, thus reducing the risk of relay fusing and capacitor damage.
Implementation Method 1
an inverter for receiving DC power stored in the battery, converting the DC power into three-phase AC power and outputting the three-phase AC power
Implementation Method 2
a motor for generating a torque using the three-phase AC power output from the inverter
Implementation Method 3
a neutral point capacitor connected to the second terminal of the first relay
Implementation Method 4
the DC voltage of the charging equipment can be boosted using inductance according to coils constituting a motor
Data Source
AI summary
A multi-input charging system and method using a motor driving system can prevent relay fusing or cutting in a motor and damage of a neutral point capacitor provided in a charging power input stage in a process of receiving external charging power through a neutral point of the motor and charging a battery.