SEQUENTIAL CLOSING OF CONTACTORS OF A POWER SUPPLY FOR ELECTRIC VEHICLES

Abstract

An electric vehicle power supply can include a pair of parallel contactors that electrically connect a vehicle to a power source. It also includes a controller that closes one contactor of the pair before the other, based on the cumulative inrush current exposure of each contactor in the pair.

Description

FIELD OF TECHNOLOGY

[0001] The present disclosure relates to operating an electric vehicle supply equipment (EVSE) for providing electrical power to a vehicle. GENERAL STATE OF THE ART

[0002] Electric vehicles may rely on one or more traction batteries to provide electrical energy to propel an electric motor. The traction batteries can be charged from a power source via an EVSE. SUMMARY

[0003] A vehicle charging system includes an electric vehicle power supply including a pair of contactors electrically connecting a vehicle to a power source and a controller that closes one contactor of the pair before the other contactor of the pair based on a cumulative exposure to inrush current from each contactor of the pair.

[0004] A method includes, after connecting an electric vehicle power supply to a vehicle, sequentially closing a pair of parallel contactors electrically connecting the vehicle to a power source such that a last contactor of the pair to be closed is closed based on a zero voltage crossing of power associated with the power source and a first contactor of the pair to be closed is not closed based on a zero voltage crossing of the power.

[0005] An electric vehicle power supply includes a charging line including a pair of contactors and a controller. After the charging line is connected to a vehicle, the controller closes the pair sequentially, such that a first contactor of the pair to be closed is closed based on a cumulative exposure to inrush current from each contactor of the pair, and a second contactor of the pair to be closed is closed based on a zero-voltage crossing of power associated with a grid. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 illustrates an example block topology of an electrified vehicle with powertrain and energy storage components. Fig. Figure 2 illustrates an example block diagram of an EVSE with high-voltage buses and contactors. Fig. Figure 3 illustrates an example flowchart of a process for operating the EVSE to charge the vehicle. DETAILED DESCRIPTION

[0006] Embodiments are described in this specification. It should be understood, however, that the disclosed embodiments are merely examples, and other embodiments may take various and alternative forms. The figures are not necessarily to scale. Some features may be exaggerated or reduced to show details of specific components. Therefore, specific structural and functional details disclosed in this specification are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art.

[0007] Various features illustrated and described with respect to any of the figures may be combined with features illustrated in one or more other figures to produce embodiments not explicitly illustrated or described. The illustrated combinations of features provide representative embodiments for typical applications. However, various combinations and modifications of the features consistent with the teachings of this disclosure may be desirable for particular applications or implementations.

[0008] The present disclosure proposes, among other things, a system and method for controlling an EVSE for charging an electric vehicle.

[0009] Fig. 1 illustrates a plug-in hybrid-electric vehicle (PHEV). A plug-in hybrid-electric vehicle 112 may include one or more electric machines (electric motors) 114 mechanically coupled to a hybrid transmission 116. The electric machines 114 may be capable of operating as an electric motor or generator. Additionally, the hybrid transmission 116 is mechanically coupled to an internal combustion engine 118. The hybrid transmission 116 is also mechanically coupled to a driveshaft 120, which is mechanically coupled to the wheels 122. The electric machines 114 may provide propulsion and braking capability when the internal combustion engine 118 is on or off. The electric machines 114 may also serve as generators and may provide fuel efficiency benefits by recovering energy that would otherwise be lost as heat in the friction braking system.The electric machines 114 may also reduce vehicle emissions by enabling the internal combustion engine 118 to operate at more efficient speeds and by enabling the hybrid electric vehicle 112 to operate in electric mode, in which the internal combustion engine 118 is turned off under certain conditions.

[0010] A traction battery or battery pack 124 stores energy that can be used by the electric machines 114. A vehicle battery pack 124 may provide a high-voltage DC output. The traction battery 124 may be electrically coupled to one or more battery electric control modules (BECMs) 125. The BECM 125 may be provided with one or more processors and software applications configured to monitor and control various operations of the traction battery 124. The traction battery 124 may further be electrically coupled to one or more power electronics modules 126. The power electronics module 126 may also be referred to as a power inverter.One or more contactors 127 may isolate the traction battery 124 and the BECM 125 from other components when open, and couple the traction battery 124 and the BECM 125 to other components when closed. The power electronics module 126 may also be electrically coupled to the electric machines 114 and provide the ability to transfer power bidirectionally between the traction battery 124 and the electric machines 114. For example, a traction battery 124 may provide a DC voltage, while the electric machines 114 may operate on three-phase AC power. The power electronics module 126 may convert the DC voltage to three-phase AC power for use by the electric machines 114.In a regeneration mode, the power electronics module 126 can convert the three-phase alternating current from the electric machines 114, which act as generators, into DC voltage compatible with the traction battery 124. The description in this document applies equally to a pure electric vehicle. In a pure electric vehicle, the hybrid transmission 116 can be a manual transmission connected to the electric machine 114, and the internal combustion engine 118 may not be present.

[0011] In addition to providing motive power, the traction battery 124 may provide power to other vehicle electrical systems. A vehicle may include a direct current (DC / DC) converter module 128 that converts the high-voltage DC output of the traction battery 124 into a low-voltage DC supply compatible with other low-voltage loads of the vehicle. An output of the DC / DC converter module 128 may be electrically coupled to an auxiliary battery 130 (e.g., a 12V battery).

[0012] The vehicle 112 may be a battery electric vehicle (BEV) or a plug-in hybrid electric vehicle (PHEV) in which the traction battery 124 may be recharged by an external power source 136. The external power source 136 may be a connection to an electrical outlet. The external power source 136 may be an electrical power distribution network or grid, such as provided by a utility company. The external power source 136 may be electrically coupled to an electric vehicle power supply (EVSE) 138. The EVSE 138 may provide circuitry and controls to manage the transfer of energy between the power source 136 and the vehicle 112. The external power source 136 may provide DC or AC electrical power to the EVSE 138. The EVSE 138 may include a charging plug 140 for plugging into a charging socket 134 of the vehicle 112.The charging receptacle 134 may be any type of connector configured to transfer power from the EVSE 138 to the vehicle 112. The charging receptacle 134 may be electrically coupled to a charging device or an on-board power conversion module 132. The power conversion module 132 may condition the power supplied by the EVSE 138 to provide the proper voltage and current levels to the traction battery 124. The power conversion module 132 may interface with the EVSE 138 to coordinate the delivery of power to the vehicle 112. The EVSE connector 140 may have pins that mate with corresponding recesses of the charging receptacle 134. Alternatively, various components described as electrically coupled may transfer power using wireless inductive coupling.

[0013] One or more electrical loads 146 may be coupled to the high-voltage bus. The electrical loads 146 may have an associated controller that optionally operates and controls the electrical loads 146. Examples of electrical loads 146 may include a heating module, an air conditioning module, or the like.

[0014] The various components discussed may have one or more associated controllers to control and monitor the operation of the components. The controllers may communicate via a serial bus (e.g., Controller Area Network (CAN)) or via separate conductors. A system controller 150 may be present to coordinate the operation of the various components. It should be noted that system controller 150 is used as a general term and may include one or more control devices configured to perform various operations in the present disclosure. For example, system controller 150 may be programmed to enable a powertrain control function to operate the powertrain of vehicle 112. System controller 150 may further be programmed to enable a telecommunications function with various entities (e.g., a server) via a wireless network (e.g.,a mobile network).

[0015] The system controller 150 and / or the BECM 125 may be programmed individually or in combination to perform various operations with respect to the traction battery 124. For example, the system controller 150 and / or the BECM 125 may be configured to communicate with the EVSE 138 to operate and facilitate the battery charging process. Referring to Fig. 2 is an exemplary block diagram of an EVSE 138 and a portion of the EVSE circuitry. With continued reference to Fig. 1, the EVSE 138 may be configured to receive AC power from the power source 136 on a power source side. The EVSE 138 may be further configured to output AC power to the vehicle 112 on a vehicle side. A positive high-voltage (HV) bus 202a and a negative HV bus 202b may be connected between the power source side and the vehicle side of the EVSE circuit and configured to transfer electrical energy between the power source 136 and the vehicle 112. In one example, the positive and negative HV buses 202a, 202b may be directly connected between the power source side and the vehicle side, such that the AC power received from the power source 136 and the AC power output to the vehicle 112 have the same characteristics (e.g., voltage, frequency, or the like) associated with it.Alternatively, if the AC power output to the vehicle 112 has different characteristics than the AC power received from the power source, additional circuitry (not shown) may be provided to the EVSE 138 to facilitate power transformation. In the present disclosure, a positive main contactor MC+ 204a may be disposed on the positive HV bus 202a, and a negative main contactor MC- 204b may be disposed on the negative HV bus 202b. The main contactors 204a and 204b may selectively open and close to connect the power source side and the vehicle side of the EVSE 138.

[0016] The operations of the main contactors 204a and 204b may be controlled by an EVSE controller 206. The EVSE controller 206 may be configured to control the opening and closing of the main contactors 204a and 204b based on various factors obtained from the vehicle 112 and the power source 136. For example, the EVSE 138 may be provided with communication capabilities to communicate with the vehicle 112 and receive information related to the condition of the traction battery 124 (e.g., battery SOC, temperature). As discussed above, the system controller 150 and the BECM 125 of the vehicle 112 may communicate with the EVSE 138 and provide the information about the traction battery 124 to facilitate vehicle charging.In response to detecting that the EVSE connector 140 is paired with the vehicle 112, data communication may be established between the EVSE 138 and the vehicle 112 in preparation for charging. The controller 206 may start the charging process by closing the two main contactors 204a and 204b. One method is to close the main contactors 204a and 204b sequentially, one after the other, with a short period of time in between. For example, the positive main contactor 204a may be closed first, followed by the negative main contactor 204b. In this example, the power source 136 is not connected to the vehicle 112 until the negative (i.e., subsequent) main contactor 204b is closed. The EVSE controller 206 may alternate the closing sequence between the positive and negative main contactors 204a and 204b so that the contacts may have a uniform state of wear.

[0017] As discussed above, AC power is supplied to the vehicle 112 to charge the traction battery 124. The AC current at the positive HV bus 204a and the negative HV bus 204b may be in the form of a sinusoidal wave, as illustrated in waveform diagram 210. To further minimize the influence of inrush current, the controller 206 may be configured to operate the main contactors 204a and 204b to close at a voltage zero crossing point 212, as illustrated in waveform diagram 210. Alternatively, since the charging circuit is not closed and thus no inrush current occurs when only the first main contactor is closed, the first contactor may be closed at any time regardless of the phase of the waveform. The EVSE controller 206 may be configured to only command the downstream main contactor to close at the zero voltage crossing point 212 to mitigate the inrush current.Despite efforts to mitigate the inrush current, the timing of the second main contactor closing may not be 100% accurate due to various factors. A small amount of inrush current may still be generated once the charging circuit is closed upon closing the subsequent main contactor. The EVSE 138 may further be equipped with one or more current sensors 214 to monitor the current on the positive and negative HV buses 202a and 202b.

[0018] With reference to Fig. 3 illustrates an exemplary flow diagram of a process 300 for operating the EVSE. With continued reference to the Fig. 1 and Fig.2, the process 300 may be implemented via the EVSE controller 206. At operation 302, the EVSE controller 206 establishes a data communication connection with the vehicle 112 in response to detecting that the vehicle 112 has been connected to the EVSE 138 via the connector 140. As discussed above, the EVSE controller 206 may be configured to communicate with the system controller 150 as well as the BECM 125 via the EVSE connector 140, which is configured to support data communication protocols. Additionally or alternatively, one or more wireless communication connections (e.g., Wi-Fi) may be established between the EVSE 138 and the vehicle 112 to enable data communication. At operation 304, the EVSE controller 206 receives vehicle information related to battery charging from the vehicle 112.The vehicle information may include various entries that may be used to operate the EVSE 138 to control the battery charging process. For example, the vehicle information may include a current SOC used as the starting SOC for charging the traction battery 124. As a general rule, a lower starting SOC (e.g., 20%) may be associated with a higher starting charge power and thus possibly a higher inrush current when the second main contactor 204 is closed. Conversely, a higher starting SOC (e.g., 70%) may be associated with a lower starting charge power and thus possibly a lower inrush current. The vehicle information may further include a temperature of the traction battery 124 measured by a temperature sensor (not shown). The vehicle information may further include a battery and charging configuration (e.g.,Voltage, power limit) associated with the traction battery 124. Once the vehicle information is received, the EVSE controller 206 adjusts the settings accordingly to prepare for the charging process.

[0019] At operation 306, the EVSE 206 operates one of the main contactors 204 with a shorter lifetime (greater cumulative exposure to inrush current) to close it such that one of the positive or negative HV bus 202a, 202b is connected between the power source side and the vehicle side. Then, at operation 308, the EVSE controller 206 operates the other main contactor with a longer lifetime (e.g., a better condition) to close it, activating the charging circuit to begin charging the traction battery 124. The positive and negative main contactors 204a, 204b may have different lifetimes / conditions associated with them depending on their usage history. For example, a main contactor 204 exposed to more frequent and higher inrush current may have a shorter lifetime associated with it compared to the other main contactor 204 exposed to less frequent and lower inrush current.The lifespan / condition of each main contactor can be evaluated based on various factors (discussed below) and recorded in memory accessible to the EVSE controller 206. Since the charging circuit is not activated until the second main contactor is closed, the first main contactor to close has a shorter lifespan compared to the second main contactor to close. Therefore, a more consistent combined lifespan between the two main contactors 204 can be achieved.

[0020] At operation 310, the EVSE controller 206 measures the inrush current generated by the closing of the second main contactor via one of the current sensors 214. As discussed above, the inrush current should ideally be zero because the controller 206 commands the second main contactor 204 to close at the zero voltage crossing point. However, the timing to close the second main contactor 204 at a zero voltage crossing may not be completely accurate, and a small amount of inrush current may be generated. At operation 312, the EVSE controller 206 evaluates the impact of the inrush current on the life degradation of the second main contactor and updates the life property associated with the second main contactor. The life degradation of the second main contactor 204 can be quantified and evaluated in various ways. For example, it can be evaluated that a higher inrush current (e.g.,10 A) causes the equivalent of a higher lifetime degradation (e.g., 0.1%), whereas a lower inrush current (e.g., 2 A) can be assessed to cause the equivalent of a lower lifetime degradation (e.g., 0.02%). The EVSE 206 records the updated lifetime characteristic of the second main contactor 204 in memory. The next time vehicle charging is initiated, the EVSE 206 determines the sequence for closing the main contactors 204 based on the updated lifetime characteristics of both main contactors.

[0021] In addition to using the measured inrush current, there are alternative methods for assessing the wear of the main contactors. For example, the EVSE controller 206 may be configured to assess the life degradation of the main contactors 204 based on the starting SOC of the traction battery 124 in addition to or instead of the inrush current as measured by the current sensor 214. In general, a lower starting SOC of the traction battery 124 may be associated with a higher amount of inrush current, and a higher starting SOC of the traction battery 124 may be associated with a lower amount of inrush current. Therefore, a lower starting SOC may be assessed as causing the equivalent of greater life degradation, and a higher starting SOC may be assessed as causing the equivalent of less life degradation.

[0022] Additionally or alternatively, the EVSE 206 may be further configured to reverse the closing sequence of the main contactors each time a new charging process begins, regardless of the inrush current or the starting SOC.

[0023] The algorithms, methods, or processes disclosed in this document may be executable by or implemented by a computer, controller, or processing device, which may include any dedicated electronic control unit or programmable electronic control unit. Furthermore, the algorithms, methods, or processes may be stored in many forms as computer- or controller-executable data and instructions, including, but not limited to, information permanently stored on non-writable storage media, such as read-only memory devices, and information modifiably stored on writable storage media, such as compact discs, random access memory devices, or other magnetic and optical media. The algorithms, methods, or processes may also be implemented in software-executable objects.Alternatively, the algorithms, methods, or processes may be implemented in whole or in part using suitable hardware components, such as application-specific integrated circuits, field-programmable gate arrays, state machines, or other hardware components or devices, or a combination of firmware, hardware, and software components.

[0024] While exemplary embodiments are described above, these embodiments are not intended to describe all possible forms encompassed by the claims. The terms used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure. The terms "processor" and "processors" may be used interchangeably in this specification, as may the terms "controller" and "controllers."

[0025] As previously described, the features of various embodiments may be combined to form further embodiments of the invention that may not be explicitly described or illustrated. While various embodiments may have been described as providing advantages or being preferred over other prior art embodiments or implementations with respect to one or more desired characteristics, one of ordinary skill in the art will understand that one or more features or characteristics may be compromised to achieve desired overall system attributes depending on the specific application and implementation. These attributes may include, but are not limited to, strength, durability, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, etc.Thus, embodiments that are described as less desirable than other embodiments or prior art implementations with respect to one or more characteristics are not outside the scope of the disclosure and may be desirable for particular applications.

[0026] According to the present invention, a vehicle charging system is provided, comprising: an electric vehicle power supply including a pair of contactors configured to electrically connect a vehicle to a power source, and a controller programmed to close one contactor of the pair before the other contactor of the pair based on a cumulative exposure to inrush current from each contactor of the pair.

[0027] According to one embodiment, the controller is further programmed to close the other contactor of the pair based on a zero voltage crossing of the power associated with the power source.

[0028] According to one embodiment, the cumulative exposure to inrush current of one contactor of the pair is greater than that of the other contactor of the pair.

[0029] According to one embodiment, the controller is further programmed to update a parameter indicative of the cumulative inrush current exposure of one contactor of the pair or to update a parameter indicative of the cumulative inrush current exposure of the other contactor of the pair.

[0030] According to one embodiment, the controller is further programmed to close one contactor of the pair before the other contactor of the pair in response to a request to charge the vehicle.

[0031] According to one embodiment, the pair is parallel.

[0032] According to the present invention, a method includes: after connecting an electric vehicle power supply to a vehicle, sequentially closing a pair of parallel contactors configured to electrically connect the vehicle to a power source such that a last contactor of the pair to be closed is closed based on a zero voltage crossing of power associated with the power source and a first contactor of the pair to be closed is not closed based on a zero voltage crossing of the power.

[0033] In one aspect of the invention, the method includes closing the first contactor of the pair based on a cumulative exposure to inrush current of the first contactor of the pair.

[0034] In one aspect of the invention, the cumulative exposure to inrush current of the first contactor of the pair is greater than that of the last contactor of the pair.

[0035] In one aspect of the invention, the method includes updating a parameter indicative of the cumulative inrush current exposure of the first contactor of the pair or updating a parameter indicative of inrush current exposure of the last contactor of the pair.

[0036] In one aspect of the invention, the sequential closing occurs in response to a request to charge the vehicle.

[0037] According to the present invention, there is provided an electric vehicle power supply comprising: a charging line including a pair of contactors; and a controller programmed, after the charging line has been connected to a vehicle, to sequentially close the pair such that a first contactor of the pair to be closed is closed based on a cumulative exposure to inrush current from each contactor of the pair, and a second contactor of the pair to be closed is closed based on a zero voltage crossing of power associated with a grid.

[0038] According to one embodiment, the cumulative exposure to inrush current of the first contactor of the pair is greater than a cumulative exposure to inrush current of the second contactor of the pair.

[0039] According to one embodiment, the controller is further programmed to update a parameter indicative of the cumulative exposure to inrush current of the first contactor of the pair or to update a parameter indicative of the cumulative exposure to inrush current of the second contactor of the pair.

[0040] According to one embodiment, the controller is further programmed to sequentially close the pair in response to a request to charge the vehicle.

[0041] According to one embodiment, the pair is parallel.

Claims

[1] Vehicle charging system comprising: an electric vehicle power supply including a pair of contactors configured to electrically connect a vehicle to a power source, and a controller programmed to close one contactor of the pair before the other contactor of the pair based on a cumulative exposure to inrush current from each contactor of the pair. [2] The vehicle charging system of claim 1, wherein the controller is further programmed to close the other contactor of the pair based on a zero voltage crossing of the power associated with the power source. [3] The vehicle charging system of claim 1, wherein the cumulative inrush current exposure of one contactor of the pair is greater than that of the other contactor of the pair. [4] The vehicle charging system of claim 1, wherein the controller is further programmed to update a parameter indicative of the cumulative inrush current exposure of one contactor of the pair and to update a parameter indicative of the cumulative inrush current exposure of the other contactor of the pair. [5] The vehicle charging system of claim 1, wherein the controller is further programmed to close one of the pair of contactors before the other of the pair of contactors in response to a request to charge the vehicle. [6] The vehicle charging system of claim 1, wherein the pair is in parallel. [7] Method comprising: after connecting an electric vehicle power supply to a vehicle, sequentially closing a pair of parallel contactors configured to electrically connect the vehicle to a power source such that a last contactor of the pair to be closed is closed based on a zero voltage crossing of power associated with the power source and a first contactor of the pair to be closed is not closed based on a zero voltage crossing of the power. [8] The method of claim 7, further comprising closing the first contactor of the pair based on a cumulative exposure to inrush current of the first contactor of the pair. [9] The method of claim 8, wherein the cumulative exposure to inrush current of the first contactor of the pair is greater than that of the last contactor of the pair. [10] The method of claim 8, further comprising updating a parameter indicative of the cumulative inrush current exposure of the first contactor of the pair and updating a parameter indicative of inrush current exposure of the last contactor of the pair. [11] The method of claim 8, wherein the sequential closing occurs in response to a request to charge the vehicle. [12] Power supply for electric vehicles, comprising: a charging line including a pair of contactors; and a controller programmed, after the charging line has been connected to a vehicle, to close the pair sequentially such that a first contactor of the pair to be closed is closed based on a cumulative exposure to inrush current from each contactor of the pair, and a second contactor of the pair to be closed is closed based on a zero voltage crossing of power associated with a grid. [13] The electric vehicle power supply of claim 12, wherein the cumulative inrush current exposure of the first contactor of the pair is greater than a cumulative inrush current exposure of the second contactor of the pair. [14] The electric vehicle power supply of claim 12, wherein the controller is further programmed to update a parameter indicative of the cumulative exposure to inrush current of the first contactor of the pair and to update a parameter indicative of the cumulative exposure to inrush current of the second contactor of the pair. [15] The electric vehicle power supply of claim 12, wherein the controller is further programmed to sequentially close the pair in response to a request to charge the vehicle.

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