EV Drive Inverter Charging Using Motor Inductors for Voltage Boost
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Solution Overview
Problem
Existing electric drive systems for vehicles face challenges in efficiently charging batteries from direct current energy sources with voltages lower than the nominal battery voltage, requiring complex and costly solutions.
Innovation Solution
The method involves using a system with three switches to control the coupling of the electric three-phase motor's neutral point and the battery's negative potential line to the direct current charging connection, allowing charging from both matching and lower voltage direct current sources, utilizing the inductors of the electric three-phase motor as a boost converter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a battery is charged from a direct current energy source with voltage lower than the nominal battery voltage, then charging compatibility is improved, but additional voltage boosting equipment and system complexity are required
Solution Approach 1:
The inverter's inductors are designed to serve dual functions: operating as part of the three-phase motor drive system during vehicle operation and functioning as a boost converter during charging operations. This multi-functionality eliminates the need for separate voltage boosting equipment, allowing the battery to accept charging from both nominal voltage sources (800V) and lower voltage sources (400V) without additional hardware
Solution Approach 2:
The charging system utilizes components already present in the electric drive system (the inverter and its inductors) to perform the voltage boosting function. The existing inductors that are necessary for motor operation are repurposed to automatically perform voltage conversion during charging, making the system self-sufficient and eliminating the need for external or separate voltage boosting equipment
2Adaptability or versatility
If a dedicated boost converter is added to enable charging from lower voltage sources, then charging adaptability is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges the charging function with the existing inverter unit by utilizing its inductors for voltage boosting. Instead of adding a separate boost converter, the inverter's components are integrated into the charging circuitry, allowing the same hardware to handle both motor drive and voltage conversion functions during charging
Solution Approach 2:
The inverter is designed to perform multiple functions: it operates as a standard inverter during motor drive and as a boost converter during charging operations. This universal design allows the system to adapt to different charging voltage sources without requiring additional dedicated equipment
3Productivity
If the inverter uses pulse width modulation to charge the battery from lower voltage, then charging efficiency is improved, but control complexity increases
Solution Approach 1:
The system dynamically switches between different operating modes based on the charging voltage source. When charged from a lower voltage source (400V), the inverter operates in boost converter mode using pulse width modulation to efficiently transfer energy. When charged from a nominal voltage source (800V), it operates in direct charging mode. This dynamic adaptation allows the system to optimize charging efficiency for each scenario while managing control complexity through standardized control algorithms
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 cost-effective and efficient battery charging from direct current energy sources with varying voltages, using the electric three-phase motor's inductors to boost lower voltages to the nominal battery voltage, thus simplifying the charging process.
Implementation Method 1
utilizing the inductors of the electric three-phase motor as a boost converter
Data Source
AI summary
A method for operating an electric drive system of a vehicle where the electric drive system has an electric three-phase motor, a battery, and an inverter via which the electric three-phase motor is couplable electrically to the battery. A neutral point of the electric three-phase motor is couplable electrically to a positive pole connection of a direct current charger connection of the electric drive system. A negative potential line of the battery is couplable electrically to a negative pole connection of the direct current charger connection of the electric drive system. The neutral point is couplable electrically via a first switch to the positive pole connection. The negative potential line is couplable electrically via a second switch to the negative pole connection. The positive pole connection is couplable electrically via a third switch to a tap of an intermediate circuit capacitor.