Ground Compactor Converter Frequency Control for Battery Life
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Solution Overview
Problem
Rechargeable batteries in ground compaction devices experience reduced operation time and service life due to the need for increased motor currents when voltage drops, leading to thermal deterioration and higher cooling requirements.
Innovation Solution
A converter apparatus adjusts the alternating current voltage frequency based on the rechargeable battery's direct current voltage, reducing frequency when the voltage falls below a threshold to maintain consistent power and reduce motor currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the converter provides alternating current voltage at a fixed control frequency, then the electric motor can operate at constant power, but the motor currents must be increased when the rechargeable battery voltage falls, leading to thermal deterioration and reduced battery service life
Solution Approach 1:
The converter dynamically adjusts the output frequency based on the rechargeable battery voltage level. When voltage drops below the threshold, the converter reduces the operating frequency proportionally, preventing excessive current draw and thermal stress on the battery, thus extending battery service life while maintaining adequate motor performance
Solution Approach 2:
The system changes the operating parameters (frequency) of the electric motor based on battery voltage conditions. By reducing frequency when voltage drops, the system maintains a safer operating current range, preventing thermal deterioration and extending battery life
2Power
If the converter provides alternating current voltage at a fixed control frequency, then the electric motor can operate at constant power, but the lower voltage increases slip in the motor, leading to higher cooling requirements
Solution Approach 1:
The converter dynamically adjusts the output frequency based on the rechargeable battery voltage level. When voltage drops below the threshold, the converter reduces the operating frequency proportionally, preventing excessive current draw and thermal stress on the battery, thus extending battery service life while maintaining adequate motor performance
Solution Approach 2:
The system changes the operating parameters (frequency) of the electric motor based on battery voltage conditions. By reducing frequency when voltage drops, the system maintains a safer operating current range, preventing thermal deterioration and extending battery life
3Productivity
If the converter provides alternating current voltage at a fixed control frequency, then the electric drive can operate at full capacity, but the higher currents required when voltage falls lead to a reduction in rechargeable battery operation time
Solution Approach 1:
The converter dynamically adjusts the output frequency based on the rechargeable battery voltage level. When voltage drops below the threshold, the converter reduces the operating frequency proportionally, preventing excessive current draw and thermal stress on the battery, thus extending battery service life while maintaining adequate motor performance
Solution Approach 2:
The system changes the operating parameters (frequency) of the electric motor based on battery voltage conditions. By reducing frequency when voltage drops, the system maintains a safer operating current range, preventing thermal deterioration and extending battery life
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
Extends battery operation time, reduces cooling requirements, and prolongs battery service life by preventing excessive current draw and thermal stress.
Implementation Method 1
a converter apparatus (4) for transforming a direct current voltage (U) which can be drawn from the energy storage (3) into an alternating current voltage for the electric drive (2)
Data Source
AI summary
A ground compaction device has a working device for generating a working movement for ground compaction, an electric drive for driving the working device, an electrical energy storage for providing electrical energy for the electric drive, and a converting apparatus for converting a direct current voltage that can be drawn from the energy storage into an alternating current voltage for the electric drive. The converting apparatus is designed to provide the alternating voltage at a predetermined control frequency when the direct current voltage drawn from the energy storage is present at a direct current voltage value above a predetermined threshold voltage value, and to provide the alternating current voltage at a reduced frequency which is lower than the control frequency when the direct current voltage obtained from the energy storage is present at a direct current voltage value equal to or below the threshold voltage value.