Dual-Inverter EV Drive Control for Battery Overcurrent Balancing
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Solution Overview
Problem
Existing drive systems using multiple batteries face issues with overcurrent due to variations in internal resistance among batteries, leading to inefficiencies and potential damage.
Innovation Solution
A control system adjusts the ON-time of switching elements in inverters to balance current output from batteries with varying internal resistances, using PWM control to ensure consistent current averaging and phase interleaving to reduce ripple and improve power factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple batteries are connected in parallel to supply power to the electric motor, then the reliability of the vehicle is improved, but overcurrent occurs in batteries with lower internal resistance
Solution Approach 1:
The control part dynamically adjusts the ON-time parameter of switching elements in each inverter based on real-time current detection. When a battery outputs excessive current, the control part reduces the ON-time of its corresponding inverter's switching elements, thereby changing the operational parameter to balance current distribution and prevent overcurrent while maintaining reliable power supply from multiple batteries
2Adaptability or versatility
If batteries with different internal resistances are used in parallel, then the availability of power supply is improved, but current distribution becomes unbalanced
Solution Approach 1:
The control part implements a feedback mechanism by continuously detecting the current output from each battery and adjusting the ON-time of switching elements accordingly. This closed-loop control ensures that batteries with different internal resistances contribute balanced current to the electric motor, maintaining stable current distribution while preserving the adaptability of having multiple power sources with varying characteristics
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 overcurrent, optimizes current distribution, reduces ripple, and enhances power efficiency in electric vehicle drive systems.
Implementation Method 1
a control part that performs PWM control on the first inverter and the second inverter such that an ON-time of the first switching element in one cycle of the first alternating current becomes shorter than an ON-time of the second switching element
Data Source
AI summary
A drive system includes: a first inverter that outputs first alternating current by switching first direct current with a switching element (first switching element), to an electric motor generating power for propelling a vehicle; a second inverter that supplies, to the electric motor, second alternating current having the same frequency as the first alternating current by switching direct current with a switching element (second switching element); and a control part that performs PWM control on the first inverter and the second inverter such that an ON-time of the first switching element in one cycle of the first alternating current becomes longer than an ON-time of the second switching element when the direct current is smaller than the direct current.