TRU Inverter Power Conversion for Multi-Source AC Compatibility
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Solution Overview
Problem
Transport refrigeration units (TRUs) face sub-optimal alternating current electrical power supply from external AC sources, requiring conversion to suitable frequencies and voltages, and there is a need for diverse internal power sources to ensure reliable operation.
Innovation Solution
An apparatus comprising a power converter with a rectifier, first inverter, DC link, and second inverter, along with a power distribution unit and DC-DC converter, which can utilize external AC power, internal electrical generators, and batteries to provide flexible and efficient electrical power supply to TRUs, including conversion of AC to DC voltage and management of power flow by a controller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external AC power source is used to supply electrical power to TRU, then power supply availability is improved, but the alternating current electrical power characteristics (frequency and voltage) may be sub-optimal or unsuitable for TRU operation
Solution Approach 1:
A power converter is introduced as an intermediary device between the external AC power source and the TRU. The power converter includes a rectifier that converts AC to DC, and an inverter that converts DC back to AC with controlled frequency and voltage characteristics, thereby adapting the external power source output to match TRU requirements
Solution Approach 2:
The power converter dynamically changes the electrical parameters (frequency and voltage) of the power supply. The inverter stage adjusts the output frequency and voltage levels to match the specific requirements of the TRU, transforming sub-optimal external AC power into suitable operating conditions
2Adaptability or versatility
If battery is used as internal power source for TRU operation, then power supply flexibility is improved, but battery degradation occurs and service life is reduced
Solution Approach 1:
The system performs preliminary actions by charging the battery from external AC power sources when available and conditions are favorable. The controller monitors battery state of charge and external power availability, charging the battery in advance during low-stress periods to reduce the depth of discharge cycles during operation, thereby extending battery life
Solution Approach 2:
The controller implements feedback control by continuously monitoring battery state of charge, temperature, and discharge/charge rates. Based on this feedback, the system adjusts charging parameters and discharge limits to optimize battery longevity while maintaining operational flexibility
3Adaptability or versatility
If power converter is provided to convert external AC power to suitable characteristics, then power characteristics compatibility is improved, but device complexity increases
Solution Approach 1:
The power converter is designed with multi-functionality to justify its complexity. It can operate in multiple modes: converting external AC to DC for battery charging, converting DC to AC for TRU power supply, and potentially providing isolation and protection functions. This universal capability reduces the need for separate dedicated devices for each function
4Reliability
If diverse internal power sources (generator and battery) are provided, then power supply reliability is improved, but device complexity and management difficulty increase
Solution Approach 1:
The power distribution unit implements dynamic switching between different power sources based on real-time conditions. The controller continuously evaluates the state of the generator, battery, and external power sources, dynamically selecting the optimal power source or combination thereof to supply the TRU, thereby managing complexity through adaptive control rather than fixed configurations
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
The apparatus ensures reliable and efficient electrical power supply to TRUs by converting sub-optimal external AC power and utilizing internal power sources, reducing battery degradation and extending service life, while managing power flow to meet demand and store excess energy effectively.
Implementation Method 1
a rectifier, a first inverter and a DC link, internal to the power converter, the DC link being electrically connected to an output of the rectifier
Implementation Method 2
an output of the first inverter being electrically couplable to the transport refrigeration unit
Implementation Method 3
a second inverter having an input configured to be electrically connected to an electrical generator and an output electrically connected to the power distribution unit or to the DC link of the power converter, wherein the second inverter is configured to convert an alternating current voltage supplied at the input into a direct current voltage
Implementation Method 4
convert a voltage supplied to the DC-DC converter by the power distribution unit from a second voltage magnitude to a first voltage magnitude for supply to the DC link
Data Source
Figure 1
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Figure 2B
AI summary
The present disclosure relates to an apparatus 100 configured to supply electrical power to a transport refrigeration unit 110, the apparatus 100 comprising: a power converter 120 including a rectifier 122, a first inverter 124 and a DC link 121, internal to the power converter 120, the DC link 121 being electrically connected to an output of the rectifier 122 and an input of the first inverter 164, an input of the rectifier 122 being electrically connectable to a power source external to the apparatus 100 at a connection port 170 of the apparatus 100 and an output of the first inverter 124 being electrically couplable to the transport refrigeration unit 110; a power distribution unit 140 electrically coupled to the DC link 121 of the power converter 120; and a second inverter 164 having an input configured to be electrically connected to an electrical generator 160 and an output electrically connected to the power distribution unit 140 or to the DC link 121 of the power converter 120, wherein the second inverter 164 is configured to convert an alternating current voltage supplied at the input into a direct current voltage for supply at the output.