CN-122008806-A - Optimal bus voltage and switching frequency strategy

Abstract

A transport refrigeration system is provided and includes a Trailer Refrigeration Unit (TRU), a battery for providing power to the TRU, an electrical system, and a controller. The electrical system includes a Direct Current (DC) bus electrically interposed between the battery and the TRU. The electrical system also includes an inverter and a boost converter disposed on the DC bus. The controller includes a memory unit that stores first, second, and third efficiency tables for the TRU, the inverter, and the boost converter, respectively, and a processor. The processor sets an operation target of the TRU and controls the inverter and the boost converter according to the voltage of the battery, the first, second, and third efficiency tables, and real-time operating conditions to achieve the operation target.

Inventors

• Shen Zaigui
• I. Agelman
• L. Ah Nei is many
• D. Ginsberg
• LIAO XUQIANG

Assignees

• 开利公司

Dates

Publication Date

20260512

Application Date

20251104

Priority Date

20241104

Claims (20)

1. 1. A transport refrigeration system comprising: a Trailer Refrigeration Unit (TRU); A battery for providing power to the TRU; An electrical system including a Direct Current (DC) bus electrically interposed between the battery and the TRU, and further including an inverter and a boost converter disposed on the DC bus, and A controller, the controller comprising: A memory unit storing a first efficiency table, a second efficiency table, and a third efficiency table for the TRU, the inverter, and the boost converter, respectively, and A processor for setting an operation target of the TRU and controlling the inverter and the boost converter according to the voltage of the battery, the first, second, and third efficiency tables, and real-time operation conditions to achieve the operation target.
2. 2. The transport refrigeration system of claim 1 wherein the controller is distributed between the inverter and the boost converter.
3. 3. The transport refrigeration system of any of claims 1 or 2 wherein the controller controls the inverter and the boost converter by issuing first and second signals to the inverter and the boost converter, respectively.
4. 4. The transport refrigeration system of claim 3 wherein the first signal and the second signal comprise Pulse Width Modulated (PWM) signals.
5. 5. The transport refrigeration system of any of claims 1-4 wherein the first, second, and third efficiency tables are based on historical data and are updateable.
6. 6. The transport refrigeration system of any of claims 1-5 wherein the operational target includes a compressor speed.
7. 7. The transport refrigeration system of claim 6, wherein the real-time operating conditions include at least one or more of an ambient temperature and pressure characteristic surrounding the TRU, a temperature and pressure characteristic of a container to be regulated by the TRU, a pressure and flow rate characteristic of the TRU, and an additional electrical characteristic of the electrical system.
8. 8. The transport refrigeration system of claim 6, wherein the processor is configured to: Determining a maximum efficient voltage demand for said compressor speed and a voltage difference between said voltage of said battery and said voltage demand, Modulating the switching frequency of the boost converter to compensate for the voltage difference with maximum efficiency, an The switching frequency of the inverter is modulated to build a sinusoidal voltage output from the boost converter output with maximum efficiency.
9. 9. A transport refrigeration system comprising: a Trailer Refrigeration Unit (TRU); A load; a battery for providing power to the TRU and the load; an electrical system including a Direct Current (DC) bus electrically interposed between the battery and the TRU and the load, and further including an inverter for each TRU and each load and a boost converter for some of the inverters disposed on the DC bus, and A controller, the controller comprising: A memory unit storing a first efficiency table, a second efficiency table, and a third efficiency table for the TRU and the load, the inverter, and the boost converter, respectively, and A processor for setting operation targets of the TRU and the load and controlling the inverter and the boost converter according to the voltage of the battery, the first efficiency table, the second efficiency table, and the third efficiency table, and real-time operation conditions to achieve the operation targets.
10. 10. The transport refrigeration system of claim 9, wherein the first efficiency table, the second efficiency table, and the third efficiency table are based on historical data and are updateable.
11. 11. The transport refrigeration system of any of claims 9 or 10, wherein the operational objective of the TRU includes a compressor speed.
12. 12. The transport refrigeration system of claim 11, wherein the real-time operating conditions include at least one or more of an ambient temperature and pressure characteristic surrounding the TRU and the load, a temperature and pressure characteristic of a vessel to be regulated by the TRU and the load, a pressure and flow rate characteristic of the TRU and the load, and an additional electrical characteristic of the electrical system.
13. 13. The transport refrigeration system of claim 11, wherein the processor is configured to: Determining a maximum efficient voltage demand for said compressor speed and a voltage difference between said voltage of said battery and said voltage demand, Modulating the switching frequency of the boost converter to compensate for the voltage difference with maximum efficiency, an The switching frequency of the inverter is modulated to build a sinusoidal voltage output from the boost converter output with maximum efficiency.
14. 14. A method of operating a transport refrigeration system including a Trailer Refrigeration Unit (TRU) and a battery for powering the TRU, the method comprising: setting a compressor speed of the TRU for a target temperature of the vessel; Determining a voltage demand for the compressor speed with reference to an efficiency table of the TRU; determining a voltage difference between the voltage of the battery and the voltage demand, and The voltage difference is compensated for to achieve the target temperature by controlling an inverter and a boost converter disposed on a Direct Current (DC) bus of an electrical system electrically interposed between the battery and the TRU according to efficiency tables of the inverter and the boost converter and real-time operating conditions.
15. 15. The method of claim 14, wherein controlling the inverter and the boost controller comprises issuing Pulse Width Modulation (PWM) signals to the inverter and the boost converter.
16. 16. The method of claim 15, wherein the method further comprises modulating the PWM signal to the inverter and the boost converter.
17. 17. The method of claim 16, wherein the PWM signal modulated to the inverter changes a duty cycle of the inverter to construct a sinusoidal voltage output from a boost converter output.
18. 18. The method of claim 16, wherein the PWM signal modulated to the boost converter changes a duty cycle of the boost converter to obtain a desired output voltage.
19. 19. The method of any of claims 14-18, further comprising generating the efficiency tables of the TRU, the inverter, and the boost converter based on historical data, and updating the efficiency tables of the TRU, the inverter, and the boost converter.
20. 20. The method of any of claims 14-19, wherein the real-time operating conditions include at least one or more of an ambient temperature and pressure characteristic surrounding the TRU, a temperature and pressure characteristic of a vessel to be regulated by the TRU, a pressure and flow rate characteristic of the TRU, and an additional electrical characteristic of the electrical system.

Description

Optimal bus voltage and switching frequency strategy Technical Field The present disclosure relates to compressor systems and, more particularly, to an optimal Direct Current (DC) bus voltage and switching frequency strategy for compressor systems. Background Refrigerated vehicles transport perishable or temperature sensitive cargo within a logistics network. Refrigerated vehicles typically include a Trailer Refrigeration Unit (TRU) that conditions the environment within a storage area (e.g., a container or trailer) of the vehicle in which the cargo is stored during transport. The TRU includes a refrigeration system powered by an energy source, and the like. Traditionally, in the case of tractor-trailer systems where the storage area is located within the trailer, the trailer has been provided with an internal combustion engine to supply power to the TRU. The internal combustion engine of the TRU is separate from the internal combustion engine of the powered tractor. In recent years, an electric power source has been used to supply power to TRUs, rather than using an internal combustion engine. Such an electrical power source may include a battery that charges electrical energy for use from a power grid and/or a generator coupled to the trailer axle. This increases the fuel consumption of the internal combustion engine of the tractor but allows smaller batteries to be used. Disclosure of Invention In accordance with aspects of the present disclosure, a transport refrigeration system is provided and includes a Trailer Refrigeration Unit (TRU), a battery for providing power to the TRU, an electrical system, and a controller. The electrical system includes a Direct Current (DC) bus electrically interposed between the battery and the TRU. The electrical system also includes an inverter and a boost converter disposed on the DC bus. The controller includes a memory unit that stores first, second, and third efficiency tables for the TRU, the inverter, and the boost converter, respectively, and a processor. The processor sets an operation target of the TRU and controls the inverter and the boost converter according to the voltage of the battery, the first, second, and third efficiency tables, and real-time operating conditions to achieve the operation target. According to one or more additional and/or alternative embodiments, the controller is distributed between the inverter and the boost converter. According to one or more additional and/or alternative embodiments, the controller controls the inverter and the boost converter by issuing a first signal and a second signal to the inverter and the boost converter, respectively. According to one or more additional and/or alternative embodiments, the first signal and the second signal comprise Pulse Width Modulated (PWM) signals. According to one or more additional and/or alternative embodiments, the first efficiency table, the second efficiency table, and the third efficiency table are based on historical data and are updateable. According to one or more additional and/or alternative embodiments, the operating target includes a compressor speed. According to one or more additional and/or alternative embodiments, the real-time operating conditions include at least one or more of an ambient temperature and pressure characteristic surrounding the TRU, a temperature and pressure characteristic of a vessel to be regulated by the TRU, a pressure and flow rate characteristic of the TRU, and an additional electrical characteristic of the electrical system. According to one or more additional and/or alternative embodiments, the processor is configured to determine a maximum efficient voltage demand for the compressor speed and a voltage difference between the voltage of the battery and the voltage demand, to modulate a switching frequency of the boost converter to compensate for the voltage difference with maximum efficiency, and to modulate the switching frequency of the inverter to construct a sinusoidal voltage output from the boost converter output with maximum efficiency. In accordance with aspects of the present disclosure, a transport refrigeration system is provided and includes a Trailer Refrigeration Unit (TRU), a load, a battery for providing power to the TRU and the load, an electrical system, and a controller. The electrical system includes a Direct Current (DC) bus electrically interposed between the battery and the TRU and the load. The electrical system also includes an inverter for each TRU and each load, and a boost converter for some of the inverters disposed on the DC bus. The controller includes a memory unit that stores first, second, and third efficiency tables for the TRU and the load, the inverter, and the boost converter, respectively, and a processor. The processor sets an operating target of the TRU and the load and controls the inverter and the boost converter according to the voltage of the battery, the first, second, and third efficiency tables,