EV Regenerative Braking Circuit for DC Bus Voltage Stability
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Solution Overview
Problem
In electric vehicles, particularly those with uneven terrain, regenerative power and battery rechargeability fluctuate, leading to unstable DC bus voltage due to improper distribution between battery charging and regenerative brake circuit power consumption.
Innovation Solution
The electric vehicle incorporates a power converter and a bidirectional power conversion device to manage regenerative power distribution, with the regenerative brake circuit operating at a higher voltage than the charging power converter, stabilizing DC bus voltage by optimizing power distribution between battery charging and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If regenerative power is distributed between battery charging and regenerative brake circuit without voltage threshold differentiation, then power utilization is simplified, but DC bus voltage becomes unstable
Solution Approach 1:
The patent applies parameter changes by establishing different voltage thresholds for the regenerative brake circuit and charging power converter. The regenerative brake circuit operates at a first voltage threshold while the charging power converter operates at a second voltage threshold, creating a hierarchical power distribution strategy that stabilizes DC bus voltage under varying regenerative power conditions
2Use of energy by moving object
If regenerative power is fully utilized for battery charging, then energy recovery is maximized, but voltage instability occurs when regenerative power exceeds battery rechargeable power
Solution Approach 1:
The patent segments the power distribution control into two distinct voltage thresholds: a first voltage threshold for the regenerative brake circuit and a second voltage threshold for the charging power converter. This segmentation allows the system to first utilize regenerative power for braking when voltage exceeds the first threshold, and only charge the battery when voltage exceeds the higher second threshold, preventing voltage instability while maximizing energy recovery
Solution Approach 2:
The patent introduces voltage threshold comparison as an intermediary control mechanism between regenerative power generation and power distribution. By comparing the detected voltage against predetermined first and second thresholds, the system mediates power flow distribution, ensuring stable voltage while optimizing energy recovery through controlled power routing to either the regenerative brake circuit or battery charging
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
Stabilizes DC bus voltage by effectively managing regenerative power distribution, preventing voltage fluctuations during varying regenerative power and battery charge conditions.
Implementation Method 1
a power converter configured to convert input direct current (DC) power into alternating current (AC) power and output it to the motor, and to convert regenerative electric power input from the motor into direct current (DC) power and output it
Implementation Method 2
a bidirectional power conversion device connected to the power converter, configured to operate in either a state in which DC power is input from the storage battery, its voltage is converted, and the converted voltage DC power is output to the power converter, or a state in which DC power is input from the power converter, its voltage is converted, and the converted voltage DC power is output to the storage battery for charging power control
Implementation Method 3
a regenerative brake circuit configured to perform a power processing operation to store or consume the DC power input from the power converter, wherein a first operating voltage at which the regenerative brake circuit starts the power processing operation is higher than a second operating voltage at which the bidirectional power conversion device starts the charging power control
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
An electric vehicle comprises a motor and a storage battery, and travels using the motor as a power source driven by electric power supplied from the storage battery. During regenerative braking, the storage battery is charged by regenerative electric power generated by the motor. The electric vehicle includes a power converter, a bidirectional power conversion device, and a regenerative brake circuit. The electric vehicle is configured such that a first operating voltage at which the regenerative brake circuit starts a power processing operation is higher than a second operating voltage at which the bidirectional power conversion device starts charging power control.