Hybrid Vehicle DC Link Voltage Stabilization
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Solution Overview
Problem
In series parallel hybrid vehicle systems, the disconnection of a rechargeable battery from the direct-current link leads to unstable operation and potential system shutdown due to voltage variations, making it difficult to maintain stable drive conditions.
Innovation Solution
The implementation of a vehicle control apparatus with a constant direct-current voltage control section and separate inverter control sections for the power generator and motor, which allows for independent torque control and voltage regulation, ensuring stable operation even when the battery is disconnected from the direct-current link.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the battery is disconnected from the direct-current link, then the system can avoid battery deterioration and continue operation, but the voltage of the direct-current link becomes unstable and the inverter operation becomes unstable
Solution Approach 1:
A capacitor is introduced as an intermediary component connected to the direct-current link. The capacitor maintains voltage stability by storing and releasing electrical energy as needed, compensating for the absence of the battery and preventing voltage fluctuations that would otherwise cause inverter operation instability.
Solution Approach 2:
The control system dynamically adjusts the operating parameters of the inverter based on the detected direct-current link voltage. When the battery is disconnected, the controller modifies the inverter's switching characteristics and power conversion parameters to maintain stable operation despite voltage variations, ensuring continuous reliable operation.
2Duration of action of stationary object
If the battery is disconnected from the direct-current link, then the system can operate without battery deterioration, but the entire vehicle system may stop due to unstable inverter operation
Solution Approach 1:
The capacitor is pre-connected to the direct-current link as a backup energy storage device. In the event of battery disconnection or failure, the capacitor immediately provides the necessary electrical energy buffer, preventing system shutdown and ensuring continuous operation without requiring battery intervention.
Solution Approach 2:
The capacitor serves as a mediator between the power source and the inverter load. It smooths out voltage fluctuations and provides stable DC bus voltage, enabling the inverter to operate reliably even when the battery is disconnected, thus preventing vehicle system stoppage.
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 stable drive conditions by maintaining constant direct-current link voltage and achieving desired axle torque, even when the battery is not connected, thereby preventing system shutdown and ensuring efficient operation.
Implementation Method 1
an inverter configured to drive a power generator; an inverter configured to drive a motor
Implementation Method 2
a rechargeable battery connected to the direct-current link
Data Source
Figure 1
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AI summary
A vehicle system according to embodiments is capable of achieving a stable drive, and includes an internal combustion engine 10; a first elect ric motor 30; a first power transmission mechanism 20 configured to trans mit a revolution of the internal combustion engine 10 to the first electric m otor 30 and a second power transmission mechanism 70; a second electri c motor 60 connected to the second power transmission mechanism 70; a first inverter 40 configured to drive the first electric motor 30; a second inv erter 50 connected to the first inverter 40 via a direct-current link and driv e the second electric motor 60; an axle 80 configured to rotate by being c oupled to the second power transmission mechanism 70, a voltage detecto r VS configured to detect a direct-current voltage of the direct-current link; a constant direct-current voltage control section 110 configured to output di rect-current section energy so that the direct-current voltage supplied from the voltage detector VS and the link voltage command are equalized, and a torque computing section 120 configured to compute a torque comman d of the first electric motor 30 and a torque command of the second elect ric motor 60 so that an output torque of the axle 80 and the axle torque command are equalized and a voltage of the direct-current link becomes c onstant