Generator Excitation Control for Cooling System Starting Currents
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Solution Overview
Problem
Conventional cooling systems for transport units require oversized primary energy sources or complex operating strategies to manage high starting currents, leading to increased acquisition and operational costs, as well as inefficient energy supply utilization.
Innovation Solution
A cooling system with a generator featuring excitation control and modular design, utilizing asynchronous electric motors and power factor correction, allows for reduced starting currents and optimized energy distribution among multiple refrigeration circuit modules, eliminating the need for complex regulation or oversized generators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the generator is dimensioned to cover the entire operating range including peak starting currents, then the power supply capability is improved, but the acquisition cost and operational cost increase significantly
Solution Approach 1:
The generator's excitation current is dynamically adjusted based on the instantaneous power demand. During starting currents of refrigeration circuit module elements, the excitation control increases the excitation current to provide additional reactive power, allowing the generator to cover peak demands without being permanently oversized.
Solution Approach 2:
The excitation control changes the magnetic field strength of the generator by adjusting the excitation current, thereby changing the reactive power output. This parameter change allows the generator to adapt its power supply capability to match the instantaneous load requirements, particularly during starting current events.
2Reliability
If an oversized generator is provided to handle peak starting currents, then the power supply reliability is improved, but the energy efficiency deteriorates due to underutilization during normal operation
Solution Approach 1:
The generator operates dynamically with variable excitation current rather than being statically oversized. During normal operation, the excitation current is reduced to match the lower power demand, improving energy efficiency. During peak starting currents, the excitation current is increased to maintain reliability.
Solution Approach 2:
The excitation control system automatically adjusts the generator's reactive power output in response to load changes, particularly detecting and responding to starting current events of refrigeration circuit module elements without external intervention.
3Loss of energy
If complex operating strategies are implemented to limit maximum current consumption, then the power consumption is controlled, but the device complexity and operational costs increase
Solution Approach 1:
The excitation control acts as an intermediary between the generator and the refrigeration circuit module elements. Instead of controlling the consumers to limit their current draw, the excitation control mediates by providing additional reactive power support during starting currents, allowing uncontrolled hard connection while managing the overall power demand.
4Power
If the generator is dimensioned for peak starting currents, then the starting capability is improved, but the system robustness deteriorates due to electrical oscillations and overvoltages
Solution Approach 1:
The excitation control applies preliminary anti-action by increasing the excitation current before and during the switching on of refrigeration circuit module elements. This preemptive increase in reactive power support counteracts the harmful electrical oscillations and overvoltages that would otherwise occur during hard starting currents.
Solution Approach 2:
The excitation control system monitors the electrical network conditions and adjusts the excitation current in response to detected load changes. This feedback mechanism allows the generator to maintain stable operation during starting currents by dynamically compensating for electrical oscillations.
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 reduces energy consumption, enables efficient startup of refrigeration circuit elements, and optimizes energy usage, resulting in a more cost-effective and robust cooling system that can handle high starting torques without overloading the generator.
Implementation Method 1
a generator (5) for providing an energy supply for the cooling system... the generator (5) has an excitation control... the magnitude and gradient of the excitation current being dependent on the current load torque of the drive unit
Implementation Method 2
the at least one drive unit for the refrigeration circuit module element is an asynchronous electric motor
Data Source
AI summary
The invention relates to a cooling system for cooling a transport unit, comprising a generator for providing an energy supply for the cooling system, and at least one refrigeration circuit module connected to the energy supply, which has a switchable drive unit for a refrigeration circuit module element. The cooling system is characterized in that the generator has an excitation control.