Regenerative Braking Power Control for Stable Auxiliary Voltage
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Solution Overview
Problem
In regenerative braking systems, rapid fluctuations in voltage supplied to auxiliary machines occur during transitions between regeneration and non-regeneration periods due to the slower response of auxiliary-machine generators, potentially hindering normal operation and requiring large capacitors that increase system size and cost.
Innovation Solution
A regenerative braking system with a controller that manages power flow between generators, rectifiers, inverters, and power storage, ensuring stable voltage by activating/deactivating generators and power converters based on regeneration status, using a first and second electric power converting apparatus to maintain predetermined voltage levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a large-capacitance smoothing capacitor is connected to the auxiliary-machine DC line to reduce voltage fluctuations, then voltage stability is improved, but system size and cost increase
Solution Approach 1:
The control device performs preliminary action by predicting the start and end of regeneration periods in advance, and pre-adjusting the power supply configuration before voltage fluctuations occur. The controller switches the auxiliary-machine generator to a deactivated state before the regeneration period ends, and activates it before the next regeneration period begins, thereby preventing voltage fluctuations without requiring large smoothing capacitors.
Solution Approach 2:
The control device acts as an intermediary that coordinates between the DC/DC converter and the auxiliary-machine generator. It manages the power flow switching and activates/deactivates the generator at appropriate times to compensate for voltage fluctuations, replacing the need for large-capacitance smoothing capacitors with intelligent control.
2Loss of energy
If the auxiliary-machine generator output is made zero during regeneration period to maximize energy conservation, then energy efficiency is improved, but voltage fluctuations increase
Solution Approach 1:
The system dynamically adjusts the operating state of the auxiliary-machine generator based on the regeneration period status. During regeneration periods, the generator is deactivated to maximize energy conservation. At the critical transition moments (start and end of regeneration), the controller dynamically switches the generator state and activates the DC/DC converter to maintain voltage stability, achieving both energy efficiency and voltage stability.
Solution Approach 2:
The control device changes the operating parameters of the auxiliary-machine generator and DC/DC converter based on regeneration period detection. It adjusts the generator output from zero during regeneration to active state at transitions, and controls the DC/DC converter power transmission ratio to maintain voltage within the normal operating range, thereby resolving the contradiction between energy conservation and voltage stability.
3Loss of energy
If the auxiliary-machine generator is activated in a state where its output is zero immediately after the end of regeneration period, then energy conservation is improved, but rapid voltage reduction occurs
Solution Approach 1:
The control device performs preliminary action by detecting the end of the regeneration period in advance and activating the auxiliary-machine generator before the voltage fluctuation occurs. It also pre-activates the DC/DC converter to ensure smooth power transition, preventing rapid voltage reduction while maintaining energy conservation benefits.
Solution Approach 2:
The control device uses feedback from voltage detection to adjust the generator activation timing and DC/DC converter power transmission ratio. It continuously monitors the auxiliary-machine DC line voltage and adjusts the power supply configuration to maintain voltage within the normal operating range, preventing rapid voltage reduction while preserving energy conservation.
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
Reduces voltage fluctuations during regeneration operation transitions, ensuring stable power supply to auxiliary machines and optimizing energy conservation.
Implementation Method 1
a first rectifier circuit that is connected to the first generator, rectifies output of the first generator, and outputs the output of the first generator as direct current electric power to a first direct current line
Implementation Method 2
a first electric power converting apparatus that converts the electric power of the first direct current line, and supplies the electric power of the first direct current line to the second direct current line
Implementation Method 3
an inverter connected between the first direct current line and an electric motor
Data Source
Figure 1
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AI summary
When regeneration operation is being performed, electric power on a main-machine side is supplied to an auxiliary-machine side, a voltage on the auxiliary-machine side is controlled to become a first voltage value predetermined on the basis of operating voltage specifications of an auxiliary apparatus, a generator on the auxiliary-machine side is deactivated to stop supply of electric power to the auxiliary-machine side, and electric power on the auxiliary-machine side is supplied to a power storage apparatus. When the regeneration operation is ended, the supply of the electric power from the main-machine side to the auxiliary-machine side is stopped, the generator on the auxiliary-machine side is activated, the generator on the auxiliary-machine side is controlled such that a voltage on the auxiliary-machine side becomes the first voltage value, electric power of the power storage apparatus is supplied to the auxiliary-machine side, and the voltage on the auxiliary-machine side is controlled to become a second voltage value higher than the first voltage value. This enables reduction of fluctuations of a voltage supplied to auxiliary machines at a time of switching of regeneration operation by travel motors.