Stabilized Voltage Supply Unit for Road Pavers
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Solution Overview
Problem
Standard electrical consumers on road construction machines cannot be operated efficiently due to varying engine speeds, which cause frequency fluctuations, leading to potential damage and limited usage, especially when the engine is not running at low speeds, necessitating special or expensive frequency-tolerant consumers or overloading the 24-volt vehicle electrical system.
Innovation Solution
A stabilized power supply unit with a universal converter circuit generates a constant mains voltage and frequency from the varying alternator output, allowing standard electrical consumers to operate independently of engine speed, using bridge rectifiers or regulated switching power supplies to ensure a stable frequency and voltage, eliminating the need for exotic connectors and reducing operational effort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If standard sockets are supplied with power by the three-phase generator directly, then the electrical capacity is sufficient, but the frequency varies with engine speed causing damage to standard electrical consumers
Solution Approach 1:
A converter circuit is introduced as an intermediary between the three-phase generator and the power supply unit. This converter circuit transforms the variable frequency AC output from the generator into a stable frequency output, thereby protecting standard electrical consumers from frequency variations while maintaining full utilization of the generator's electrical capacity
Solution Approach 2:
The converter circuit changes the frequency parameter of the electrical output from variable (dependent on engine speed) to fixed (stable frequency). This parameter transformation allows standard electrical consumers to operate reliably regardless of engine speed variations, while the converter is controlled by a control device that monitors engine speed and adjusts conversion parameters accordingly
2Reliability
If the engine speed is restricted to low speeds for standard consumers, then frequency stability is achieved, but productivity and operational flexibility are reduced
Solution Approach 1:
The system dynamically adapts to different engine speeds through the converter circuit. Instead of restricting engine operation to low speeds, the converter continuously adjusts its conversion parameters based on real-time engine speed feedback, maintaining stable output frequency across the full operational range of the engine, thereby preserving both reliability and productivity
3Adaptability or versatility
If special frequency-tolerant consumers are used, then operation at varying frequencies is possible, but additional expense is incurred
Solution Approach 1:
The converter circuit provides universal compatibility for all standard electrical consumers by transforming the variable frequency output into stable frequency regardless of the specific consumer type. This eliminates the need for expensive specialized frequency-tolerant consumers, as the converter makes the standard generator output compatible with conventional equipment
4Reliability
If the 24-volt vehicle electrical system is used for standard consumers, then frequency stability is maintained, but the electrical system becomes heavily loaded
Solution Approach 1:
The converter circuit extracts the frequency stabilization function from the 24-volt vehicle electrical system and implements it directly at the power supply level. This allows standard electrical consumers to be powered directly from the three-phase generator through the converter, bypassing the 24-volt system and avoiding overloading the vehicle's electrical system while maintaining frequency stability
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
Enables the permanent and efficient operation of standard electrical consumers like power tools and lighting equipment without overloading the vehicle electrical system, utilizing the alternator's power reserve effectively and reducing the need for additional technical effort in voltage supply, allowing standard power grid-like usage on construction sites.
Implementation Method 1
The intermediate circuit contains bridge rectifiers or a regulated switching power supply
Implementation Method 2
a universal converter circuit with which an intermediate voltage can be generated from the alternating current generator with varying frequency
Data Source
Figure 1
Figure 2
AI summary
In a road construction machine (F), in particular a road paver or a feeder for road pavers, with a primary drive unit (P) comprising an internal combustion engine (4) driving at least one three-phase generator (19) and having at least one connection device (24) for at least one standard AC load (28, 29), at least one stabilized voltage supply unit (21) is connected between the connection device (24) and the three-phase generator (19), with which standard mains voltage with a permanently stable frequency can be provided at the connection device (24) regardless of the speed of the internal combustion engine (4) driving the three-phase generator (19).