Intermediate Circuit Voltage Control for Battery-Free Cargo E-Bikes
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Solution Overview
Problem
Chainless cargo bicycles face challenges in maintaining stable operation when the drive battery unit is not providing power, as the power ratio from the battery to the electric drive is significantly higher than the generator's output, leading to instability and inefficiency in power transmission.
Innovation Solution
A control unit is introduced that electrically connects the generator and electric drive, featuring a control module to regulate the intermediate circuit voltage, a status detector to switch between battery-powered and battery-free configurations, and a switch device to manage power flow, ensuring robust operation even without a drive battery unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the drive battery unit is not providing power, then the generator must supply all power to the electric drive, but the intermediate circuit voltage becomes unstable due to fluctuating pedal power
Solution Approach 1:
The control unit continuously monitors the intermediate circuit voltage and adjusts the electric drive's power consumption accordingly. When voltage deviates from the setpoint, the control module modifies the drive power to bring voltage back to the desired level, creating a closed-loop feedback system that stabilizes the intermediate circuit despite fluctuating generator input.
Solution Approach 2:
The system dynamically changes the electric drive's power consumption parameter based on the intermediate circuit voltage level. By adjusting the drive power as a controlled variable, the system adapts to varying generator output and maintains stable operation without requiring a battery buffer.
2Productivity
If the electric drive consumes more power than the generator supplies, then the intermediate circuit voltage drops, but this causes instability in battery-free operation
Solution Approach 1:
The control unit uses feedback to monitor intermediate circuit voltage and adjust electric drive power consumption. When voltage drops below the setpoint, the system reduces drive power to prevent instability, creating a self-regulating mechanism that balances power demand with generator supply capability.
Solution Approach 2:
The system dynamically adjusts the electric drive's power consumption based on real-time intermediate circuit voltage conditions. This dynamic adaptation allows the system to optimize drive performance while maintaining stability under varying generator output conditions.
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
The control unit enables reliable and efficient operation of chainless cargo bicycles by stabilizing the intermediate circuit voltage, allowing the vehicle to function with fluctuating power inputs and preventing power exchange during negative torque, thus ensuring continuous operation and robust regulation.
Implementation Method 1
a control module 2 configured to receive a setpoint value as a reference variable and an actual value as a controlled variable and to output a control variable
Implementation Method 2
a generator (120) that can convert a user's pedaling movement into electrical current
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention relates to a control unit (1) for use in an intermediate circuit (110) of a vehicle, wherein the intermediate circuit (110) electrically connects a generator (120) and an electric drive (130), comprising: a control module (2) configured to receive a setpoint as a reference variable (w) and an actual value as a controlled variable (x) and to output a control variable (u), wherein the controlled variable (x) and the reference variable (w) have the same physical dimension; an evaluation module (3) configured to determine a manipulated variable (y) from the control variable (u), which influences the controlled variable (x) at least indirectly such that the actual value approaches the setpoint; a generator interface (4) configured to receive a generator parameter, in particular a generator power value, from the generator (120); and a drive interface (5) configured to communicate with the electric drive (130);wherein the control unit (1) is configured to determine an intermediate circuit voltage (UZ) present in the intermediate circuit (110) and to use it as a controlled variable (x). The invention further relates to a method for adapting a drive power of an electric drive (130) of a vehicle to an output power of a generator (120) of the vehicle.