Vehicle Drive System Intermediate Circuit Voltage Control
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Solution Overview
Problem
Existing electrically operated vehicle drive systems face inefficiencies in energy management across various operating states, particularly in vehicles with frequent braking and acceleration processes, as they struggle to optimize energy recovery and storage effectively.
Innovation Solution
A drive system that includes a first power source circuit with a control device, a second chargeable and dischargeable power source circuit, and an electric intermediate circuit, where detection devices for voltage and vehicle speed set a modifiable setpoint value for the intermediate circuit voltage, allowing the system to adjust power output based on vehicle speed, thereby optimizing energy management across different operating states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a fuel cell is used to generate electrical energy for the drive system, then the vehicle can operate in electric mode with reduced emissions, but the system cannot effectively handle frequent braking and acceleration processes in town center traffic
Solution Approach 1:
The patent combines a fuel cell with a double-layer capacitor buffer store in a hybrid powertrain system. The fuel cell handles steady-state power requirements while the capacitor buffer handles transient power demands during frequent braking and acceleration, allowing the system to leverage both technologies' strengths and achieve both energy efficiency and adaptability
Solution Approach 2:
The system dynamically adjusts the operating state of the fuel cell based on vehicle conditions. During frequent braking and acceleration in town center traffic, the capacitor buffer absorbs transient power demands, allowing the fuel cell to operate in a more stable, efficient operating range while still meeting overall power requirements
2Ease of operation
If the intermediate circuit voltage is kept constant to simplify control, then the system is easier to operate, but energy optimization during different operating states cannot be achieved
Solution Approach 1:
The patent implements dynamic voltage control of the intermediate circuit based on the operating state of the vehicle. The control device adjusts the intermediate circuit voltage according to whether the vehicle is accelerating, braking, or maintaining steady speed, allowing energy optimization across different operating states while maintaining manageable control complexity through state-based control logic
Solution Approach 2:
The system changes the voltage parameter of the intermediate circuit dynamically based on operating conditions. By adjusting voltage levels according to the vehicle's operating state (acceleration, braking, steady-state), the system optimizes energy management without requiring overly complex control mechanisms
3Speed
If the fuel cell output is continuously adjusted to meet instantaneous power demands, then the system responds quickly to changing conditions, but the fuel cell operates inefficiently outside its optimal operating range
Solution Approach 1:
The double-layer capacitor buffer store acts as an intermediary between the fuel cell and the drive unit. It absorbs transient power demands during acceleration and recovers energy during braking, allowing the fuel cell to operate in a stable, efficient operating range while still meeting instantaneous power requirements through the buffer
Solution Approach 2:
The capacitor buffer is pre-charged during steady-state operation and low-demand periods, storing energy in advance. During frequent braking and acceleration events, this pre-stored energy is quickly discharged to meet power demands, allowing the fuel cell to remain in its optimal operating range while still providing rapid response
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 approach enables the drive system to maintain an optimum energy state by adjusting voltage and power output according to vehicle speed, enhancing energy recovery during braking and acceleration, and reducing energy losses, thus improving overall energy efficiency.
Implementation Method 1
a drive unit (4) which can be supplied by the supply circuit in order to drive driven wheels (3) of the vehicle. In most applications, the drive unit can also carry out electrical braking with recovery of energy so that it feeds electrical energy back into the supply circuit.
Implementation Method 2
The fuel cell is suitable in particular for converting the energy contained in a chemical substance directly into electrical energy in order, for example, to drive a drive unit of an electrically operated vehicle using the acquired electrical energy.
Data Source
AI summary
A drive system for an electrically operated vehicle includes an electric drive unit operable as a motor and as a generator, a first power source circuit with a control device for controllably outputting power, a second chargeable and dischargeable power source circuit having at least one capacitor and which is connected in parallel to the drive unit, an electric intermediate circuit connected to the first and the second power source circuits and to the drive unit, a third chargeable and dischargeable power source circuit with at least one battery and which is connected to the intermediate circuit, a first detection device for detecting an electrical voltage of the intermediate circuit, which detection device is connected to the control device, and a second detection device for detecting a characteristic value of the vehicle speed and which is connected to the control device.