Variable Speed Generator Control for Transport Refrigeration
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Solution Overview
Problem
Existing transport refrigeration generator sets operate at a constant speed, leading to inefficient fuel usage and increased risk of out-of-fuel conditions, especially in varying ambient temperatures, which can result in loss of perishable cargo.
Innovation Solution
A multi-speed generator set controlled by an electronic control unit and a controller that adjusts engine speed based on fuel delivery conditions, switching between high and low speeds depending on load thresholds to optimize fuel efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the generator set operates at a constant high speed to maintain reliable power supply, then the power output stability is improved, but the fuel consumption increases
Solution Approach 1:
The generator set transitions from constant speed operation to variable speed operation, dynamically adjusting the engine speed based on actual load conditions. The controller monitors load demands and modifies the engine operating speed accordingly, allowing the system to maintain reliability when needed while reducing energy consumption during partial load conditions.
Solution Approach 2:
The system changes the operating parameters of the generator set by adjusting engine speed as a variable parameter rather than keeping it constant. The controller modifies the engine speed parameter in response to changing load conditions, enabling the system to optimize between power reliability and fuel efficiency by selecting appropriate speed levels.
2Use of energy by moving object
If the generator set operates at reduced speed to decrease fuel consumption, then the fuel efficiency is improved, but the power output capability decreases
Solution Approach 1:
The system dynamically adjusts engine speed based on real-time load monitoring. When load demands increase, the controller increases engine speed to maintain adequate power output. When loads are light, the controller reduces speed to improve fuel efficiency. This dynamic response ensures the system has sufficient power capability when needed while optimizing fuel consumption during normal operation.
Solution Approach 2:
The controller is pre-programmed with operating strategies that anticipate power requirements. The system maintains readiness to increase power output by having the controller monitor load conditions continuously and pre-establish the capability to adjust engine speed upward when demand increases, ensuring power capability is preserved without continuously operating at high speed.
3Reliability
If the generator set operates continuously at high speed, then the power supply reliability is maintained, but the service life of the generator set decreases
Solution Approach 1:
The generator set operates dynamically rather than continuously at high speed. The controller adjusts engine speed based on actual power demands, allowing the system to maintain power supply reliability when needed while reducing operational stress during lower demand periods. This variable operation reduces wear and tear on engine components, thereby extending the overall service life of the generator set.
4Power
If the generator set operates at high speed to meet peak power demands, then the power output is sufficient, but the noise level increases
Solution Approach 1:
The system dynamically adjusts engine speed to match actual power requirements. During peak demand periods, the engine operates at higher speeds to provide sufficient power output. During normal or low demand periods, the engine operates at lower speeds, which significantly reduces noise levels. This dynamic speed adjustment allows the system to meet power demands when necessary while minimizing noise pollution during routine operation.
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A generator set for a transport refrigeration unit that is operable at a first frequency and a second frequency. The generator set includes a generator and a prime mover. The generator set is controlled by an electronic control unit (ECU) that is coupled to a controller. The ECU is configured to monitor the engine operation condition to obtain an engine operation condition value; whereas the controller is configured to receive the engine operation condition value and compare the value with an engine operation condition threshold. When the engine operation condition value, for example, exceeds the engine operation condition threshold, the controller instructs the ECU to operate the engine at a first speed; and when the engine operation condition value, for example, is below the engine operation condition threshold, the controller instructs the ECU to operate the engine at a second speed that is slower than the first speed.