Time sharing control of transport refrigeration system
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Solution Overview
Problem
Conventional transport refrigeration systems require multiple power bridges and DC links to operate in both road and standby modes, which are costly and inefficient.
Innovation Solution
A transport refrigeration system utilizing a power conversion unit with two power bridges and a DC link, controlled by switches to share power between an energy storage device and a power grid during standby mode, allowing for efficient operation with reduced components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional transport refrigeration systems use separate power bridges and DC links for road mode and standby mode, then the system can operate reliably in both modes, but the device complexity and cost increase
Solution Approach 1:
The patent merges the power conversion paths for road mode and standby mode by using a single shared DC link and two power bridges that can dynamically reconfigure their connections. Instead of having separate power conversion systems for each mode, the invention combines them into one integrated system where the power bridges and DC link serve both operational modes through dynamic switching controlled by a controller.
Solution Approach 2:
The invention employs dynamic switching mechanisms where the first and second switches can change their connection states based on the operational mode. In road mode, the switches configure the power flow from the energy storage device through the first power bridge to the motor. In standby mode, the switches reconfigure to allow power flow from the power grid through the second power bridge, with the first power bridge charging the energy storage device. This dynamic reconfiguration allows one set of components to serve multiple functions.
2Adaptability or versatility
If multiple power bridges and DC links are used to support both road and standby modes, then the system has full functionality, but the manufacturing cost increases
Solution Approach 1:
The invention makes the power bridges and DC link multi-functional by enabling them to serve different purposes in different operational modes. The first power bridge can function as a DC-DC converter in road mode and as a rectifier/charger in standby mode. The second power bridge functions as an AC-DC converter in standby mode and is disconnected in road mode. This multi-functionality reduces the total number of components needed compared to having dedicated separate systems for each mode.
Solution Approach 2:
The patent combines the power conversion infrastructure for both road and standby modes into a shared system. Instead of manufacturing separate power bridges and DC links for each mode, the invention manufactures one set of power bridges and DC links that are designed to handle both modes through dynamic switching, thereby reducing manufacturing costs and component count.
3Productivity
If separate power conversion systems are used for road mode and standby mode, then each mode operates independently, but energy efficiency decreases
Solution Approach 1:
The invention enables continuous useful action by allowing the first power bridge to continuously convert DC power during standby mode while simultaneously charging the energy storage device. The dynamic switching ensures that power conversion activities are continuously productive rather than idle, maximizing the utilization of the power conversion components and improving overall energy efficiency.
Solution Approach 2:
The invention merges the power conversion and energy storage charging functions into a single integrated process during standby mode. The first power bridge simultaneously performs power conversion and charges the energy storage device, eliminating the need for separate dedicated charging circuits and improving energy efficiency by reducing power losses associated with separate conversion stages.
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 functionality of both road and standby modes using only two power bridges and one DC link, optimizing energy use and reducing costs.
Implementation Method 1
a power conversion unit configured to convert an amplitude, a frequency and a phase of an input electrical power signal
Implementation Method 2
an energy storage device configured to supply electrical power to the motor via the power conversion unit during a road mode
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A transportation refrigeration system 200 including: a transportation refrigeration unit comprising a motor 32; a power conversion unit 26 configured convert an amplitude, a frequency and a phase of an input electrical power signal, wherein the power conversion unit 26 comprises a first power bridge 262, a DC link 264 and a second power bridge 266; an energy storage device 24 configured to supply electrical power to the motor 32 via the power conversion unit 26 during a road mode; a first switch 302 configured to selectively connect the first power bridge 262 to the energy storage device 24 or the motor 32; and a second switch 304 configured to selectively connect the second power 266 bridge to the motor 32 or a power grid 30; wherein the first switch 302 and second switch 304 are positioned to connect the first power bridge 262 and second power bridge 266 to specified sources and outputs during each of the road mode and the standby mode.