CN-122003794-A - Magnetic field weakening vehicle-mounted AC charger in a vehicle connected to an AC power source

CN122003794ACN 122003794 ACN122003794 ACN 122003794ACN-122003794-A

Abstract

The charging device and system are used to charge the energy storage system of each vehicle using grid power, where all vehicles are connected to the same transformer. The apparatus and system coordinates the charging process and may employ field weakening techniques to reduce peak line voltage as necessary, as determined based on the minimum energy storage system voltage of the vehicle connected to the same transformer.

Inventors

O. M. Hayes
N. A. Lemberg

Assignees

BAE系统控制有限公司

Dates

Publication Date: 20260508
Application Date: 20241009
Priority Date: 20231012

Claims (20)

1. An apparatus associated with a charging station, the charging station comprising a transformer and a plurality of charging ports, wherein a plurality of vehicles are respectively connected to the charging station for charging respective energy storage devices using power from the transformer through a switching device, the plurality of vehicles forming a charging group, each vehicle comprising an on-board ac charger, the apparatus comprising: a communication interface; A processor configured to: Receiving real-time direct current voltages of respective energy storage systems of at least two vehicles connected to the same transformer from the vehicle-mounted alternating current charger of the at least two vehicles through the communication interface; determining a minimum dc voltage of the energy storage system in each of the at least two vehicles based on the dc voltages received from the at least two vehicles; Comparing the determined minimum DC voltage with a peak line voltage (V_LL) associated with the transformer, thereby determining whether field weakening is required, When it is determined that the field weakening is required, the processor will be further configured to: calculating reactive ac current such that the peak line voltage (v_ll) associated with the transformer is reduced to less than the determined minimum dc voltage; A value proportional to the calculated reactive ac current is transmitted to the vehicle ac charger of the at least two vehicles via the communication interface.
2. The apparatus of claim 1, further comprising a plurality of voltage sensors configured to detect a voltage of each three phase on the plurality of charging ports, and the processor is configured to determine the peak line voltage (v_ll) corresponding to the detected voltage.
3. The apparatus of claim 1, wherein the on-board ac charger includes voltage sensors for respectively detecting voltages at terminals of the conversion circuit in the vehicle, and the processor is further configured to receive the detected voltages from the voltage sensors.
4. The apparatus of claim 1, wherein the real-time direct current voltages of the respective energy storage systems of the at least two vehicles are received while each energy storage device is coupled to the same transformer and the operations of determining the minimum direct current voltage, whether field weakening is required, calculating the reactive alternating current, and transmitting a value proportional to the calculated reactive alternating current are repeated based on the received direct current voltages.
5. The apparatus of claim 1, wherein the value proportional to the calculated reactive ac current is the same for each of the at least two vehicles.
6. The apparatus of claim 1, wherein when an additional carrier is connected to one of the charging ports, a real-time dc voltage of an energy storage system in the additional carrier is received prior to charging, and the processor repeats the operations of determining the minimum dc voltage, whether field weakening is required, calculating the reactive ac current, and transmitting a value proportional to the calculated reactive ac current.
7. The device of claim 1, wherein the device is located within the charging station.
8. The apparatus of claim 1, wherein the communication interface is a wireless communication interface.
9. The apparatus according to claim 1, wherein the reactive alternating current for reducing the peak line voltage (v_ll) is determined based on Proportional Integral (PI) control.
10. The apparatus of claim 1, wherein the charging station has a plurality of transformers and a plurality of groups of charging ports, wherein a plurality of groups of carriers are connectable to the plurality of groups of charging ports by respective switching devices, wherein each group of carriers constitutes a different charging group, each charging group comprising carriers connected to the same transformer, wherein the processor is configured to calculate the reactive current required for each charging group based on a real-time voltage of the energy storage system in each group of carriers and the peak line voltage (v_ll) associated with the respective transformer.
11. An in-vehicle charging system for a vehicle, the vehicle being coupleable via a switching device to a transformer within a charging station, wherein the charging station includes a plurality of ports, the transformer configured to provide three-phase alternating current to charge an energy storage system within the vehicle, the vehicle being connectable to the ports via an alternating current charging cable, the in-vehicle charging system comprising: an ac filter comprising an inductor, the ac filter being capable of coupling to each phase of the three-phase ac power; a conversion circuit coupled to the inductor of each ac filter, the conversion circuit configured to convert the three-phase ac power received by its input terminals into dc power for a system dc bus and configured to provide independently controllable active ac current and reactive ac current; A voltage sensor for detecting a voltage of each of three phases of the input terminal, respectively; a communication interface configured to electrically communicate with at least one other carrier in a charging group, the charging group including one or more other carriers coupled to the same transformer; Wherein the on-board charging system further comprises a first processor and a second processor, wherein the first processor is configured to be set to at least one of an active fleet controller mode and an inactive fleet controller mode, wherein the processor is an active fleet controller when set to be in the active fleet controller mode, and wherein the second processor receives commands from a vehicle set to the active fleet controller when the first processor is set to be in the inactive fleet controller mode, Wherein when the first processor is the active fleet controller, the second processor is configured to close one or more switches associated with each of the three phases and determine a real-time voltage of the energy storage device in its own vehicle when a condition is met, and The first processor is configured to: Receiving real-time direct current voltages of corresponding energy storage systems of at least one other vehicle in the charging group from the vehicle-mounted charging system of the vehicle through the communication interface; Determining a minimum dc voltage in the energy storage system in each vehicle connected to the same terminal based on the received real-time dc voltage and the determined real-time voltage of the energy storage device; Determining a peak line voltage (v_ll) corresponding to the voltage detected at the input terminal of the conversion circuit; Comparing the determined peak line voltage (V_LL) with the minimum DC voltage to determine whether field weakening is required, When it is determined that field weakening is required, the first processor is further configured to: calculating a reactive ac current that causes the peak line voltage (v_ll) to be lower than the minimum dc voltage; transmitting a value proportional to the calculated reactive ac current to the vehicle-mounted charging system of the at least one other vehicle in the charging group via the communication interface; Wherein the second processor is configured to cause the conversion circuit to provide reactive ac current based on the calculated reactive ac current such that it flows through each inductor and transformer, thereby reducing the peak line voltage (v_ll).
12. The on-board charging system of claim 11, wherein setting the mode to the active or inactive fleet controller mode is based on a time at which one or more vehicles in the charging group are connected to the plurality of ports.
13. The on-board charging system of claim 11, wherein setting a mode to an active or inactive fleet controller mode is based on the real-time voltage of each of the energy storage systems of the vehicles in the charging group.
14. The in-vehicle charging system according to claim 11, wherein when the first processor is set in the active fleet controller mode, the second processor is configured to: transmitting the real-time dc voltage of the energy storage system of the vehicle through the communication interface; receiving a value proportional to the calculated reactive ac current through the communication interface; The conversion circuit in the vehicle charging system is caused to provide reactive alternating current based on the received proportional value such that it flows through each inductor and transformer, thereby reducing the peak line voltage (V LL).
15. The on-board charging system of claim 12, wherein the second processor is further configured to: regulating the system direct current bus voltage to enable the system direct current bus voltage to be basically matched with the real-time voltage of the energy storage system after the reactive alternating current is injected; Controlling one or more switches associated with the energy storage system to close when the peak line voltage (V_LL) is less than the real-time voltage of the energy storage system and the system DC bus voltage substantially matches the real-time voltage of the energy storage system, and Wherein the energy storage system is charged after controlling the one or more switches.
16. The on-board charging system of claim 15, wherein the second processor is configured to transmit the real-time voltage of the energy storage system when the energy storage system is charged when the first processor is set to be in an inactive fleet controller mode, and wherein the first processor receives the real-time voltage when the first processor is set to be in an active fleet controller mode and repeats the operations of determining the minimum direct voltage, whether field weakening is required, calculating the reactive alternating current, and transmitting a value proportional to the calculated reactive alternating current based on the received direct voltage.
17. The on-board charging system according to claim 15, wherein when the first processor is set in active fleet controller mode, the second processor is configured to detect the real-time voltage of the energy storage system in the vehicle as the energy storage system charges, and the first processor is configured to repeat the operations of determining the minimum direct voltage, if field weakening is required, calculating the reactive alternating current, and transmitting based on the detected real-time voltage.
18. The on-board charging system of claim 11, wherein the first processor is the second processor.
19. An on-board charging system for a vehicle, the vehicle being coupleable via a switching device to a transformer within a charging station, wherein the charging station includes a plurality of ports, the transformer configured to provide three-phase alternating current to charge an energy storage system within the vehicle, the vehicle being connectable to the ports via an alternating current charging cable, the on-board charging system comprising: an ac filter comprising an inductor, the ac filter being capable of coupling to each phase of the three-phase ac power; a conversion circuit coupled to the inductor of each ac filter, the conversion circuit configured to convert the three-phase ac power received by its input terminals into dc power for a system dc bus and configured to provide independently controllable active ac current and reactive ac current; a communication interface configured to electrically communicate with at least one other carrier in a charging group, the charging group including one or more other carriers coupled to the same transformer; And a processor configured to: transmitting a real-time direct current voltage of an energy storage system in the vehicle through a communication interface; Receiving a value proportional to the calculated reactive ac current from a vehicle having a processor set to be in an active fleet controller mode or from a dedicated external fleet controller via the communication interface, the processor being set to calculate reactive ac current based on a minimum dc voltage of the energy storage system of the vehicle in the charging group and a peak line voltage (v_ll) on the plurality of ports; Causing the conversion circuit in the vehicle charging system to provide reactive alternating current based on the received value such that it flows through each inductor, switching device and transformer, thereby reducing the peak line voltage (v_ll); After injecting the reactive alternating current, regulating a system direct current bus voltage to substantially match the real time voltage of the energy storage system, and controlling one or more switches associated with the energy storage system to close when the peak line voltage (V LL) is less than the real time voltage of the energy storage system and the system direct current bus voltage substantially matches the real time voltage of the energy storage system, Wherein the energy storage system is charged after controlling the one or more switches.
20. The on-board charging system for a vehicle according to claim 18, wherein the processor is further configured to transmit the real-time voltage of the energy storage system as the energy storage system is charged and to receive an updated value proportional to the calculated reactive ac current.

Description

Magnetic field weakening vehicle-mounted AC charger in a vehicle connected to an AC power source Technical Field The present disclosure relates to charging of vehicles such as hybrid vehicles or electric vehicles, wherein an on-board power conversion device is used to directly charge an energy storage system from an ac power source. More particularly, the present disclosure relates to coordinating charging of a plurality of vehicles in a charging group connected to an external ac power source using an onboard power converter as a charger. Background Both electric and hybrid vehicles are equipped with an electric Energy Storage System (ESS). Industry standard is to charge the ESS by connecting an external dc charger. The DC charger converts the alternating current into direct current, inputs the alternating current power supply and outputs the direct current to a DC bus of the carrier. The electric vehicle has an electric power converter for converting direct current into alternating current, thereby driving the vehicle to travel. The electric power converter of the electric vehicle may also convert alternating current to direct current for regenerative braking. U.S. patent 11,052,782 describes the use of an on-board power converter as an on-board charger that can be directly connected to an external ac power source. However, problems may occur when the passively rectified grid voltage overlaps the energy storage system voltage range (v_ LLRMS ×sqrt (2) > vbattery_min). This problem may be caused by the use of alternating current power sources, such as a utility grid. For example, 277/480V AC input power would be passively rectified to 679V DC. The voltage of the energy storage system in an electric vehicle is mainly dependent on the state of charge (SoC). Therefore, the electric vehicle charger must be able to regulate the output dc voltage so that the energy storage system can be charged both at low and high states of charge. U.S. patent 11,052,782 solves this problem by means of a field weakening technique. The field weakening technique is based on a comparison of the peak line voltage v_ll with the real-time energy storage system voltage (v_ess). The field weakening function enables the charge controller to inject reactive current into the ac input power reactance. The field weakening function will lower the V LL of the ac input and thus the dc voltage output by the rectifier. However, if multiple carriers are connected to the same external ac input power source, the real-time Energy Storage System (ESS) voltage may or may not be the same for each carrier. Furthermore, during charging, different vehicles may be connected to or disconnected from the same external power source, which may also lead to differences in the real-time energy storage system voltage. The present disclosure describes how to control one on-board charger to actively rectify an ac input to charge an energy storage system in an electric vehicle, and how to control multiple on-board chargers to operate in parallel across multiple electric vehicles. Disclosure of Invention Accordingly, the present disclosure relates to directly charging a plurality of vehicles with an ac power source, wherein each vehicle has an onboard charger. This eliminates redundant external dc chargers and associated external power conversion devices. The present disclosure also relates to control and coordination of charging a plurality of in-vehicle chargers operating in parallel in a plurality of vehicles, respectively. This coordination achieves field weakening to charge multiple carriers as needed. For example, an apparatus associated with a charging station is disclosed. The charging station includes a transformer and a plurality of charging ports. A plurality of carriers may be connected to the charging station, respectively, to charge their respective energy storage devices with power from the transformer through the switching device. The plurality of carriers may form a charging group. Each vehicle includes an onboard ac charger. The apparatus may include a communication interface and a processor. The processor may be configured to receive real-time direct current voltages of respective energy storage systems of at least two vehicles from an on-board ac charger connected to the at least two vehicles of the same transformer, determine a minimum direct current voltage of the energy storage systems in each of the at least two vehicles based on the direct current voltages received from the at least two vehicles, and compare the determined minimum direct current voltage to a peak line voltage (v_ll) associated with the transformer to determine whether field weakening is required. When it is determined that field weakening is required, the processor may be configured to calculate reactive ac current to reduce the transformer related peak v_ll below the determined minimum dc voltage. And transmitting a value proportional to the calculated ac reactive current to a