Auxiliary power module protection control for one vehicle

Abstract

From several perspectives, a method for controlling an APM contactor for a vehicle can include logging multiple APM contactor actuations within a single time step. These actuations include multiple auxiliary battery charging actuations and multiple accessory actuations. The method can further include comparing a number of these accessory actuations to a predetermined accessory actuation threshold. The method can also include restricting future APM contactor actuations in response to the finding that the number of accessory actuations is greater than or equal to the predetermined accessory actuation threshold.

Description

INTRODUCTION

[0001] The present disclosure relates to systems and methods for power system control for a vehicle.

[0002] To enhance occupant comfort and vehicle performance, vehicles may be equipped with energy storage and distribution systems configured to provide electrical power to various vehicle systems and components. Energy storage and distribution systems may include rechargeable energy storage systems (RESS) and power electronics systems. The RESS may include high-voltage traction batteries configured to store large amounts of energy for use by the vehicle's propulsion systems (e.g., electric motors and / or hybrid electric motors), and low-voltage auxiliary batteries configured to store smaller amounts of energy for use by vehicle accessories (e.g., vehicle lighting, air conditioning, entertainment systems, security / alarm systems, and / or the like). The power electronics systems may include power conversion devices (e.g., inverters, power supplies, and other electrical components).These systems include auxiliary power modules (APMs), DC / DC converters, and / or similar components, as well as circuit breakers for conversion between high-voltage and low-voltage vehicle systems. However, current vehicle energy storage and distribution systems cannot adequately reduce the wear and tear on power electronics components due to the frequent power demands of vehicle accessories.

[0003] Although current vehicle energy storage and distribution systems and procedures fulfill their purpose, there is consequently a need for a new and improved system and procedure for controlling an Auxiliary Power Module (APM) contactor for a vehicle. SUMMARY

[0004] A method for controlling an auxiliary power module (APM) contactor for a vehicle is developed according to several aspects. This method may include logging multiple actuations of the APM contactor within a single time step. These actuations include multiple auxiliary battery charging actuations and multiple accessory actuations. The method may further include comparing a number of these accessory actuations with a predefined accessory actuation threshold. Additionally, the method may include restricting future actuations of the APM contactor in response to the determination that the number of accessory actuations is greater than or equal to the predefined accessory actuation threshold.

[0005] According to another aspect of the present disclosure, logging each of the multiple actuations of the APM contactor can further include detecting an actuation of the APM contactor. Logging each of the multiple actuations of the APM contactor can further include incrementing a total actuation count variable in a non-transient memory in response to the detection of the actuation of the APM contactor. Logging each of the multiple actuations of the APM contactor can further include categorizing the actuation of the APM contactor in response to the detection of the actuation of the APM contactor. The actuation of the APM contactor is categorized as one of the multiple auxiliary battery charging actuations or as one of the multiple accessory actuations.Logging each of the multiple APM contactor actuations can further include incrementing an auxiliary battery charging actuation counter variable in the non-transient memory in response to categorizing the APM contactor actuation as one of the multiple auxiliary battery charging actuations. The auxiliary battery charging actuation counter variable stores the number of the multiple auxiliary battery charging actuations. Logging each of the multiple APM contactor actuations can further include incrementing an accessory actuation counter variable in the non-transient memory in response to categorizing the APM contactor actuation as one of the multiple accessory actuations. The accessory actuation counter variable stores the number of the multiple accessory actuations.

[0006] According to another aspect of the present disclosure, logging each of the multiple actuations of the APM contactor can include storing an actuation record in non-transient memory in response to the categorization of the APM contactor actuation. The actuation record contains an actuation time and an actuation categorization.

[0007] According to a further aspect of the present disclosure, restricting future actuations of the APM contactor can also include predicting a period of high actuation frequency, at least partially, based on multiple actuation data records in the non-transient memory. Furthermore, restricting future actuations of the APM contactor can include actuating the APM contactor into an ON state at the beginning of the high actuation frequency period. Finally, restricting future actuations of the APM contactor can include actuating the APM contactor into an OFF state at the end of the high actuation frequency period, so that the APM contactor remains continuously ON during the high actuation frequency period.

[0008] According to another aspect of the present disclosure, the method may further include determining an overall actuation trend. The overall actuation trend is a trend in the number of multiple actuations over several time steps. The method may further include comparing the overall actuation trend with a predetermined overall actuation threshold. The predetermined overall actuation threshold includes a predetermined expected overall actuation trend. The predetermined expected overall actuation trend is determined at least partially based on an expected lifetime of the APM contactor and a maximum number of actuations of the APM contactor. The method may further include restricting future accessory actuations and future auxiliary battery charging actuations in response to the finding that the overall actuation trend is greater than or equal to the predetermined expected overall actuation trend.

[0009] According to another aspect of the present disclosure, categorizing the actuation of the APM contactor can include categorizing the actuation of the APM contactor as one of several auxiliary battery charging actuations in response to the determination that the APM contactor was actuated to charge an auxiliary battery of the vehicle. Furthermore, categorizing the actuation of the APM contactor can include categorizing the actuation of the APM contactor as one of several accessory actuations in response to the determination that the APM contactor was not actuated to charge the auxiliary battery of the vehicle.

[0010] According to another aspect of the present disclosure, comparing the number of multiple accessory actuations with the specified accessory actuation threshold can further include determining an accessory actuation trend. The accessory actuation trend is a trend in the number of multiple accessory actuations over several time steps. Comparing the number of multiple accessory actuations with the specified accessory actuation threshold can further include comparing the accessory actuation trend with the specified accessory actuation threshold. The specified accessory actuation threshold includes a specified expected accessory actuation trend. The specified expected accessory actuation trend is determined at least partially based on an expected service life of the APM contactor and a maximum number of actuations of the APM contactor.Comparing the number of multiple accessory actuations with the specified accessory actuation threshold may, in response to the determination that the accessory actuation trend is greater than or equal to the specified expected accessory actuation trend, include determining that the number of multiple accessory actuations is greater than or equal to the specified accessory actuation threshold.

[0011] According to a further aspect of the present disclosure, the method may also include calculating the number of available auxiliary battery charging cycles within the time step, at least partially based on the number of multiple accessory cycles, the expected lifetime of the APM contactor, and the maximum number of cycles of the APM contactor. The method may also include estimating the number of auxiliary battery charging cycles within the time step. Furthermore, the method may include comparing the number of available auxiliary battery charging cycles with the number of estimated auxiliary battery charging cycles. Finally, the method may include limiting future auxiliary battery charging cycles in response to the finding that the number of available auxiliary battery charging cycles is less than the number of estimated auxiliary battery charging cycles.

[0012] According to a further aspect of the present disclosure, estimating the number of auxiliary battery charging cycles within the time step can also include measuring the battery temperature of an auxiliary battery of the vehicle. Estimating the number of auxiliary battery charging cycles within the time step can also include determining an estimated energy draw from the auxiliary battery during the time step. Estimating the number of auxiliary battery charging cycles within the time step can also include determining an effective energy capacity of the auxiliary battery, at least partially based on the battery temperature. Estimating the number of auxiliary battery charging cycles within the time step can also include determining an estimated charge cycle of the auxiliary battery. The estimated charge cycle is characterized by a charge cycle duty cycle and a charge cycle period.Estimating the number of estimated auxiliary battery charging operations within the time step may also include estimating the number of estimated auxiliary battery charging operations within the time step, at least partially, based on the charging cycle duty cycle and the charging cycle period.

[0013] According to another aspect of the present disclosure, restricting future auxiliary battery charging operations may also include actuating the APM contactor into an ON state, so that the APM contactor is constantly in the ON state.

[0014] A system for controlling an auxiliary power module (APM) contactor for a vehicle is being developed, based on several considerations. The system may include a traction battery, an APM contactor electrically connected to the traction battery, an auxiliary battery, low-voltage vehicle accessories, and an auxiliary power module (APM) electrically connected to the APM contactor, the auxiliary battery, and the low-voltage vehicle accessories. The APM is configured to convert a high voltage provided by the traction battery to a low voltage for use by the auxiliary battery and the low-voltage vehicle accessories. The system may also include a controller electrically connected to at least the APM contactor. The controller is programmed to log multiple actuations of the APM contactor within a single time step.The multiple activations include multiple auxiliary battery charging activations to charge the auxiliary battery and multiple accessory activations to power low-voltage vehicle accessories. The controller is further programmed to compare a number of the multiple accessory activations against a predefined accessory activation threshold. The controller is also programmed to restrict future activations of the APM contactor in response to the determination that the number of multiple accessory activations is greater than or equal to the predefined accessory activation threshold.

[0015] According to another aspect of the present disclosure, the controller is further programmed to detect an actuation of the APM contactor in order to log the multiple actuations of the APM contactor. To log the multiple actuations of the APM contactor, the controller is further programmed to increment a total actuation count variable in a non-transient memory in response to the detection of the actuation of the APM contactor. To log the multiple actuations of the APM contactor, the controller is further programmed to categorize the actuation of the APM contactor in response to the detection of the actuation of the APM contactor. The actuation of the APM contactor is categorized as one of several auxiliary battery charging actuations or as one of several accessory actuations.To log the multiple actuations of the APM contactor, the controller is further programmed to increment an auxiliary battery charging actuation counter variable in non-transient memory in response to the categorization of the APM contactor actuation as one of the multiple auxiliary battery charging actuations. The auxiliary battery charging actuation counter variable stores the number of the multiple auxiliary battery charging actuations. To log the multiple actuations of the APM contactor, the controller is further programmed to increment an accessory actuation counter variable in non-transient memory in response to the categorization of the APM contactor actuation as one of the multiple accessory actuations. The accessory actuation counter variable stores the number of the multiple accessory actuations.To log the multiple actuations of the APM contactor, the controller is further programmed to store an actuation record in non-transient memory in response to the categorization of the APM contactor actuation. The actuation record contains an actuation time and an actuation categorization.

[0016] According to another aspect of the present disclosure, the controller is further programmed to predict a period of high actuation frequency, at least partially, based on multiple actuation data sets in non-transient memory, in order to limit future actuations of the APM contactor. To limit future actuations of the APM contactor, the controller is further programmed to actuate the APM contactor into an ON state at the beginning of the high actuation frequency period. To limit future actuations of the APM contactor, the controller is further programmed to actuate the APM contactor into an OFF state at the end of the high actuation frequency period, so that the APM contactor is continuously in the ON state during the high actuation frequency period.

[0017] According to another aspect of the present disclosure, the controller is further programmed to determine an accessory actuation trend in order to compare the number of multiple accessory actuations with the predefined accessory actuation threshold. The accessory actuation trend is a trend in the number of multiple accessory actuations over several time steps. To compare the number of multiple accessory actuations with the predefined accessory actuation threshold, the controller is further programmed to compare the accessory actuation trend with the predefined accessory actuation threshold. The predefined accessory actuation threshold includes a predefined expected accessory actuation trend. The predefined expected accessory actuation trend is determined at least partially based on an expected lifetime of the APM contactor and a maximum number of actuations of the APM contactor.In order to compare the number of multiple accessory activations with the specified accessory activation threshold, the controller is further programmed to determine, in response to the finding that the accessory activation trend is greater than or equal to the specified expected accessory activation trend, that the number of multiple accessory activations is greater than or equal to the specified accessory activation threshold.

[0018] According to another aspect of the present disclosure, the controller is further programmed to calculate the number of available auxiliary battery charging cycles within the time step, at least partially, based on the number of multiple accessory cycles, the expected lifetime of the APM contactor, and the maximum number of cycles of the APM contactor. The controller is further programmed to estimate the number of auxiliary battery charging cycles within the time step. The controller is further programmed to compare the number of available auxiliary battery charging cycles with the number of estimated auxiliary battery charging cycles. The controller is further programmed to limit future auxiliary battery charging cycles in response to the finding that the number of available auxiliary battery charging cycles is less than the number of estimated auxiliary battery charging cycles.

[0019] According to another aspect of the present disclosure, the system further includes an auxiliary battery temperature sensor that is electrically connected to the controller. To estimate the number of auxiliary battery charging cycles, the controller is programmed to measure the battery temperature of an auxiliary battery in the vehicle. To estimate the number of auxiliary battery charging cycles, the controller is programmed to determine an estimated energy draw from the auxiliary battery during the time step. To estimate the number of auxiliary battery charging cycles, the controller is programmed to determine an effective energy capacity of the auxiliary battery, at least partially based on the battery temperature. To estimate the number of auxiliary battery charging cycles, the controller is programmed to determine an estimated charge cycle of the auxiliary battery.The estimated charging cycle is characterized by a charging cycle duty cycle and a charging cycle period. To estimate the number of auxiliary battery charging operations, the controller is programmed to estimate the number of auxiliary battery charging operations within the time step, at least partially, based on the charging cycle duty cycle and the charging cycle period.

[0020] According to another aspect of the present disclosure, the controller is further programmed to actuate the APM contactor into an ON state, so that the APM contactor is constantly in the ON state in order to limit future auxiliary battery charging actuations.

[0021] A method for controlling an auxiliary power module (APM) contactor for a vehicle is developed, taking several aspects into account. The method may include logging multiple APM contactor actuations within a single time step. These actuations include multiple auxiliary battery charging actuations and multiple accessory actuations. The method may also include comparing a number of accessory actuations with a predefined accessory actuation threshold. Furthermore, the method may include restricting future APM contactor actuations in response to the determination that the number of accessory actuations is greater than or equal to the predefined accessory actuation threshold.The method may further include calculating the number of available auxiliary battery charging cycles within the time step, at least partially based on the number of multiple accessory cycles, the expected lifetime of the APM contactor, and the maximum number of cycles of the APM contactor. The method may further include estimating the number of auxiliary battery charging cycles within the time step. The method may further include comparing the number of available auxiliary battery charging cycles with the number of estimated auxiliary battery charging cycles. The method may further include limiting future auxiliary battery charging cycles in response to the finding that the number of available auxiliary battery charging cycles is less than the number of estimated auxiliary battery charging cycles.

[0022] According to another aspect of the present disclosure, comparing the number of multiple accessory actuations with the specified accessory actuation threshold can further include determining an accessory actuation trend. The accessory actuation trend is a trend in the number of multiple accessory actuations over several time steps. Comparing the number of multiple accessory actuations with the specified accessory actuation threshold can further include comparing the accessory actuation trend with the specified accessory actuation threshold. The specified accessory actuation threshold includes a specified expected accessory actuation trend. The specified expected accessory actuation trend is determined at least partially based on an expected service life of the APM contactor and a maximum number of actuations of the APM contactor.Comparing the number of multiple accessory actuations with the specified accessory actuation threshold may, in response to the determination that the accessory actuation trend is greater than or equal to the specified expected accessory actuation trend, include determining that the number of multiple accessory actuations is greater than or equal to the specified accessory actuation threshold.

[0023] According to a further aspect of the present disclosure, estimating the number of auxiliary battery charging cycles within the time step can also include measuring the battery temperature of an auxiliary battery of the vehicle. Estimating the number of auxiliary battery charging cycles within the time step can also include determining an estimated energy draw from the auxiliary battery during the time step. Estimating the number of auxiliary battery charging cycles within the time step can also include determining an effective energy capacity of the auxiliary battery, at least partially based on the battery temperature. Estimating the number of auxiliary battery charging cycles within the time step can also include determining an estimated charge cycle of the auxiliary battery. The estimated charge cycle is characterized by a charge cycle duty cycle and a charge cycle period.Estimating the number of estimated auxiliary battery charging operations within the time step may also include estimating the number of estimated auxiliary battery charging operations within the time step, at least partially, based on the charging cycle duty cycle and the charging cycle period.

[0024] Further areas of application will become apparent from the description provided here. It should be understood that the description and the specific examples serve only for illustration and are not intended to limit the scope of protection afforded by this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The drawings described here serve only for illustration and are not intended to limit the scope of protection of the present disclosure in any way; they show: Fig. 1 a schematic graphical representation of a system for controlling an auxiliary power module contactor (APM contactor) for a vehicle according to an exemplary embodiment; Fig. 2 a flowchart of a procedure for controlling an auxiliary power module contactor (APM contactor) for a vehicle according to an exemplary embodiment; Fig. 3 a continuation of the schedule after Fig. 2 of the method for controlling an auxiliary power module contactor (APM contactor) for a vehicle according to an exemplary embodiment; and Fig. 4 a flowchart of a method for estimating the number of estimated auxiliary battery charging operations within a time step according to an exemplary embodiment. DETAILED DESCRIPTION

[0026] The following description is merely exemplary and is not intended to limit the present disclosure, its application or its uses.

[0027] According to the aspects of this disclosure, battery electric vehicles (BEVs), hybrid electric vehicles (HEVs), and / or the like may include an Auxiliary Power Module (APM) configured to provide power to the low-voltage vehicle accessories and / or to charge the low-voltage auxiliary batteries. According to the aspects of this disclosure, the APM may be energized / disenergized by an APM contactor, which is an electrical and / or electromechanical switch for interrupting the flow of an electric current. However, the APM contactor may experience wear due to an excessive number of switching cycles (i.e., actuations). Therefore, it is advantageous to prevent the APM contactor from exceeding the limits of its switching cycle design. Accordingly, this disclosure provides a new and improved system and method for controlling an APM contactor for a vehicle.

[0028] In Fig. Figure 1 illustrates a system for controlling an auxiliary power module (APM) contactor for a vehicle, generally designated by reference numeral 10. System 10 is shown with an exemplary vehicle 12. While a passenger car is illustrated, it should be understood that vehicle 12 can be any type of vehicle without derogating from the scope of protection of this disclosure. System 10 generally includes a controller 14, a traction battery 16, an APM contactor 18, an auxiliary power module (APM) 20, an auxiliary battery 22, and a low-voltage vehicle accessory 24.

[0029] The controller 14 is used to implement a method 100 for controlling an auxiliary power module (APM) contactor for a vehicle, as described below. The controller 14 includes at least one processor 26 and a non-transient computer-readable memory device or non-transient computer-readable memory media 28. The processor 26 can be a custom-designed or commercially available processor, a central processing unit (CPU), a graphics processing unit (GPU), an auxiliary processor among several processors associated with the controller 14, a semiconductor-based microprocessor (in the form of a microchip or chipset), a macroprocessor, a combination thereof, or generally, an instruction-executing device.

[0030] The computer-readable storage device or computer-readable storage media 28 can contain volatile and non-volatile memory, e.g., in read-only memory (ROM), read / write memory (RAM), and hold memory (KAM). KAM is persistent or non-volatile memory that can be used to store various operating variables while the processor 26 is turned off. The computer-readable storage device or computer-readable storage media 28 can be implemented using a number of storage devices, such as PROMs (programmable read-only memory), EPROMs (electrical PROMs), EEPROMs (electrically erasable PROMs), flash memory, or other electrical, magnetic, optical, or combined storage devices capable of storing data, some of which represent executable instructions, used by the controller 14 to control various systems of the vehicle 12.

[0031] The controller 14 can also consist of multiple controllers that are electrically interconnected. The controller 14 can be interconnected with additional systems and / or controllers of the vehicle 12, which allows the controller 14 to access data such as the speed, acceleration, braking, and steering angle of the vehicle 12.

[0032] The controller 14 is electrically connected to at least the APM contactor 18 and the auxiliary battery 22. According to an exemplary embodiment, the electrical connection is established, for example, using a CAN network, a FLEXRAY network, a local area network (e.g., WiFi, Ethernet, and the like), a network of serial peripheral interfaces (SPI network), or the like. It should be recognized that various additional wired and wireless techniques and communication protocols for communicating with the controller 14 are within the scope of protection of this disclosure. It should further be recognized that the electrical communication within the scope of protection of this disclosure also includes the power and / or energy transfer between electrical devices (e.g., using conductive wires and / or wireless power transfer techniques).

[0033] The traction battery 16 stores and provides electrical energy in the form of direct current (DC) for propulsion and the high-voltage power supply (e.g., 400 volts) of the vehicle systems. According to one exemplary embodiment, the traction battery 16 contains multiple battery cells (e.g., lithium-ion battery cells) connected electrically in series and / or parallel to provide increased voltage and / or current capability. According to a non-limiting example, the multiple battery cells are housed in a casing configured to protect them from mechanical vibration, water ingress, and dust ingress. The casing is also configured to provide temperature control (e.g., using a liquid cooling system, a resistance heating system, and / or the like).According to an exemplary embodiment, the traction battery 16 further comprises a battery management system (BMS) configured to monitor battery characteristics, such as the state of charge (SOC), state of health (SOH), temperature, and / or the like, and to transmit these characteristics to the controller 14. According to a non-limiting example, the BMS includes a BMS controller electrically connected to multiple BMS sensors located within the housing of the traction battery 16. According to an exemplary embodiment, the traction battery 16 provides a DC voltage via a positive and a negative output terminal. The positive and negative output terminals are electrically connected to a high-voltage side of the APM 20 via the APM contactor 18, as discussed in more detail below.According to some embodiments, the controller 14 is electrically connected to the traction battery 16, e.g. to monitor the SOC of the traction battery 16.

[0034] The APM contactor 18 is used to connect / disconnect the APM 20 from the traction battery 16. According to an exemplary embodiment, the APM contactor 18 is an electromechanical device designed for making or breaking electrical connections in high-voltage circuits. According to a non-limiting example, the APM contactor 18 includes a set of contacts (not shown), an electromagnet (not shown), and a control circuit (not shown). The set of contacts includes movable and stationary contact points that can be brought together or separated by the electromagnet. The electromagnet generates a magnetic field when energized by the circuit. The magnetic field attracts or repels the movable contact points, thereby actuating the APM contactor 18.

[0035] When the controller 14 sends a signal to the control circuit during operation, the control circuit energizes the electromagnet, closing the contacts and allowing an electric current to flow between the traction battery 16 and the APM 20. Conversely, when the control circuit deactivates the electromagnet, the contacts open, interrupting the current flow between the traction battery 16 and the APM 20. It should be recognized that the APM contactor 18 can be implemented using any electronically controllable switch, including relays, electronic solid-state switches (e.g., transistors), and / or the like, without infringing upon the scope of protection of this disclosure. The APM contactor 18 is electrically connected to the controller 14 as discussed above.

[0036] According to an exemplary embodiment, the APM contactor 18 has a limited maximum number of actuations due to mechanical deterioration of its components (e.g., the set of contacts). The maximum number of actuations is the maximum number of times the APM contactor 18 can be actuated (i.e., connected or disconnected) before an electrical or mechanical failure of the APM contactor 18 is expected. By defining an expected lifetime of the APM contactor 18 (e.g., ten years), a nominal number of actuations permissible within a specific time step (e.g., one day) can be calculated based on the maximum number of actuations. The maximum number of actuations and the expected lifetime are also referred to as the design limits of the APM contactor.

[0037] The Auxiliary Power Module (APM) 20 is used to convert the high-voltage power provided by the traction battery 16 into low-voltage power suitable for supplying power to the vehicle's auxiliary systems 12. According to one exemplary embodiment, the APM 20 is implemented as a DC / DC converter, such as a buck-boost converter, a step-down converter, an unbalanced primary induction converter (SEPIC), and / or the like. It should be recognized that the APM 20 can be implemented using any circuit topology or architecture capable of DC / DC conversion. According to some embodiments, operation of the APM 20, including, for example, an activation state, a duty cycle, a conversion ratio, a voltage setpoint, and / or the like, is controlled by the controller 14 using electrical signals (e.g.,The APM 20 is controllable by analog and / or digital electrical signals. It includes a high-voltage side configured to receive high-voltage power and a low-voltage side configured to output low-voltage power. The high-voltage side of the APM 20 is connected to the traction battery 16 via the APM contactor 18, allowing the controller 14 to connect / disconnect the APM 20 to / from the traction battery 16 and consequently power / disconnect the APM 20. The low-voltage side of the APM 20 is connected to the auxiliary battery 22 and the low-voltage vehicle accessory 24, as discussed in more detail below. In some embodiments, the controller 14 is electrically connected to the APM 20, for example, to monitor power transfer from the APM 20 and / or to control its operation.

[0038] The auxiliary battery 22 stores electrical energy in the form of direct current (DC) for the low-voltage power supply (e.g., twelve volts) of the vehicle systems and provides this electrical energy. According to a non-limiting example, the auxiliary battery 22 is used to provide electrical energy to the low-voltage vehicle accessory 24 when the APM 20 is switched off. According to an exemplary embodiment, the auxiliary battery 22 contains one or more battery cells (e.g., lead-acid battery cells) that are electrically connected in series and / or parallel to provide increased voltage and / or current capability. According to a non-limiting example, the one or more battery cells are housed in an enclosure configured to protect the one or more battery cells from mechanical vibration, water ingress, and dust ingress.The housing is also configured to provide temperature control (e.g., using a liquid cooling system, a resistance heating system, and / or the like). According to one exemplary embodiment, the auxiliary battery 22 provides a DC voltage via a positive and a negative output terminal. The positive and negative output terminals are electrically connected to the low-voltage side of the APM 20. According to some embodiments, the controller 14 is electrically connected to the auxiliary battery 22, for example, to monitor power input / output of the auxiliary battery 22 and / or state of charge (SOC) of the auxiliary battery 22.

[0039] According to one exemplary embodiment, the controller 14 is electrically connected to the auxiliary battery 22 to monitor the voltage of the auxiliary battery 22 and to estimate its state of charge (SOC). If the state of charge of the auxiliary battery 22 falls below a predetermined threshold (e.g., eighty percent), the controller 14 can use the APM contactor 18 to supply energy to the APM 20 in order to charge the auxiliary battery 22, as discussed in more detail below. According to some embodiments, the auxiliary battery 22 also includes a charging controller configured to manage and regulate the charging of the auxiliary battery 22.

[0040] The total amount of energy that can be stored in the auxiliary battery 22 is referred to as the effective energy capacity of the auxiliary battery 22. According to an exemplary embodiment, the effective energy capacity of the auxiliary battery 22 varies with temperature due to, for example, temperature-dependent chemical and / or electrochemical processes or reactions within the auxiliary battery 22. Accordingly, according to a non-limiting example, the amount of energy required to fully charge or fully discharge the auxiliary battery 22 is temperature-dependent. Therefore, the auxiliary battery 22 also includes an auxiliary battery temperature sensor 30.

[0041] The auxiliary battery temperature sensor 30 is used to measure the temperature of the auxiliary battery 22. According to a non-limiting example, the auxiliary battery temperature sensor 30 includes a sensing element and a signal conditioning circuit. The sensing element detects temperature changes and converts them into electrical signals. According to a non-limiting example, the sensing element includes a thermocouple and / or a thermistor. The signal conditioning circuit amplifies and processes the electrical signals generated by the sensing element to provide temperature information to the controller 14. The auxiliary battery temperature sensor 30 is electrically connected to the controller 14, as discussed above.

[0042] Therefore, based on the temperature of the auxiliary battery 22, which is obtained using the auxiliary battery temperature sensor 30, the controller 14 can determine the effective energy capacity of the auxiliary battery 22 and consequently determine an amount of energy required to charge the auxiliary battery 22 based on the state of charge of the auxiliary battery 22.

[0043] The low-voltage vehicle accessory 24 is used to provide additional features and / or functionality for the vehicle 12. Within the scope of this disclosure, the low-voltage vehicle accessory 24 includes any system and / or component of the vehicle 12 configured to operate using low-voltage electrical power (e.g., twelve volts). When the APM 20 is energized (i.e., the APM contactor 18 is closed), the low-voltage vehicle accessory 24 is powered directly by the APM 20, drawing a negligible amount of energy from the auxiliary battery 22. When the APM 20 is de-energized (i.e., the APM contactor 18 is open), the low-voltage vehicle accessory 24 is powered by the energy stored in the auxiliary battery 22.

[0044] According to a non-limiting example, the low-voltage vehicle accessory 24 includes one or more of the following: a vehicle communication system (i.e., a system enabling vehicle-to-vehicle (V2V), vehicle-to-infrastructure (V2X) communication, communication via wireless local area networks (WLAN), and / or cell data communication), a vehicle camera system (i.e., one or more cameras arranged in / on the vehicle 12, e.g., for security monitoring purposes), an alarm system, a battery heating / cooling system for the traction battery 16 and / or the auxiliary battery 22, a vehicle infotainment system, interior / exterior vehicle lights, a heating, ventilation, and air conditioning (HVAC) system, and / or the like. It should be recognized that the low-voltage vehicle accessory 24 may include alternative and / or additional components without deviating from the scope of protection of this disclosure.According to some embodiments, the controller 14 is electrically connected to the low-voltage vehicle accessory 24, e.g. to monitor the power consumption of the low-voltage vehicle accessory 24 and / or to control the operation of the low-voltage vehicle accessory 24.

[0045] In Fig. Figure 2 shows a flowchart of method 100 for controlling an auxiliary power module (APM) contactor for a vehicle. Method 100 begins in block 102 and proceeds to block 104. In block 104, the controller 14 receives a request to actuate the APM contactor 18. Within the scope of this disclosure, actuation of the APM contactor 18 includes any switching of the APM contactor 18, including from an off state to an on state or from an on state to an off state. According to an exemplary embodiment, the request is received from one or more of the auxiliary batteries 22 and / or the low-voltage vehicle accessories 24. According to a non-limiting example, the request is received because it is determined that the auxiliary battery 22 requires charging.According to another non-restrictive example, the request is received because the low-voltage vehicle accessory 24 has been activated by an occupant of the vehicle 12 or by the controller 14. If no request to actuate the APM contactor 18 is received, procedure 100 continues to block 106 (. Fig. 3 via an off-page connector 3A) to enter a standby state. If a request to actuate the APM contactor 18 is received, procedure 100 continues to block 108.

[0046] In block 108, controller 14 actuates APM contactor 18 according to the request received in block 104. According to one non-restrictive example, controller 14 actuates APM contactor 18 from the off state to the on state. According to another non-restrictive example, controller 14 actuates APM contactor 18 from the on state to the off state. After block 108, procedure 100 continues to block 110.

[0047] In block 110, the controller 14 increments a total actuation count variable in the non-transient media 28 of the controller 14. Within the scope of this disclosure, the total actuation count variable is used to store a total number (i.e., count) of actuations of the APM contactor 18 performed within a given time step. Within the scope of this disclosure, the time step is a predetermined duration (e.g., one day). According to an exemplary embodiment, the total actuation count variable is reset to zero after the completion of each time step. Following block 110, the method 100 proceeds to block 112.

[0048] In block 112, the controller 14 categorizes the actuation of the APM contactor 18 performed in block 108. According to an exemplary embodiment, the actuation of the APM contactor 18 performed in block 108 is categorized as one of several auxiliary battery charging actuations or as one of several accessory actuations. Within the scope of protection of this disclosure, an auxiliary battery charging actuation is an actuation performed for the purpose of controlling the charging of the auxiliary battery 22 (i.e., starting or stopping a charging process). An accessory actuation is an actuation performed for the purpose of providing power to the low-voltage vehicle accessory 24.

[0049] According to one exemplary embodiment, the actuation of the APM contactor 18 performed in block 108 is categorized based on the information stored in the media 28 of the controller 14, which indicates the source of the request received in block 104 (e.g., one or more marker bits). According to a non-restrictive example, the actuation is categorized as an auxiliary battery charging actuation if the APM contactor 18 was actuated to charge the auxiliary battery 22. Otherwise, the actuation is categorized as an accessory actuation. According to another exemplary embodiment, the actuation of the APM contactor 18 performed in block 108 is categorized based on the measurement of the current flow to / from the auxiliary battery 22 and the low-voltage vehicle accessory 24 to determine the primary energy consumer.If the actuation of the APM contactor 18, which is carried out in block 108, is categorized as one of several auxiliary battery charging actuations, procedure 100 continues to block 114. If the actuation of the APM contactor 18, which is carried out in block 108, is categorized as one of several accessory actuations, procedure 100 continues to block 116.

[0050] In block 114, the controller 14 increments an auxiliary battery charging actuation counter variable in the non-transient media 28 of the controller 14. Within the scope of this disclosure, the auxiliary battery charging actuation counter variable is used to store a total number (i.e., count) of the multiple auxiliary battery charging acts performed within a given time step. Within the scope of this disclosure, the time step is a predetermined duration (e.g., one day). According to an exemplary embodiment, the auxiliary battery charging actuation counter variable is reset to zero after completion of each time step. Following block 114, the method 100 proceeds to block 118, as discussed in more detail below.

[0051] In block 116, the controller 14 increments an accessory actuation counter variable in the non-transient media 28 of the controller 14. Within the scope of this disclosure, the accessory actuation counter variable is used to store a total number (i.e., count) of the multiple accessory actuations performed within a given time step. Within the scope of this disclosure, the time step is a predetermined duration (e.g., one day). According to an exemplary embodiment, the accessory actuation counter variable is reset to zero after the completion of each time step. Following block 116, the method 100 proceeds to block 118.

[0052] In block 118, the controller 14 stores an actuation record for the actuation of the APM contactor 18 performed in block 108 in the media 28 of the controller 14. In other words, the controller 14 logs the actuation of the APM contactor 18 performed in block 108 in the media 28 of the controller 14. Within the scope of protection of this disclosure, the actuation record contains at least one time point of the actuation of the APM contactor 18 performed in block 108 (i.e., an actuation time point), and an actuation categorization of the actuation of the APM contactor 18 performed in block 108. The actuation categorization is one of: an auxiliary battery charging actuation or an accessory actuation, as determined in block 112. According to an exemplary embodiment, the actuation record further contains the current value of the total actuation count variable, the auxiliary battery charging actuation count variable, and the accessory actuation count variable.According to another exemplary embodiment, the actuation data record also contains a length and / or time remaining in the current time step. After block 118, method 100 continues to block 120.

[0053] In block 120, the controller 14 determines an accessory actuation trend. Within the scope of this disclosure, the accessory actuation trend is a trend (i.e., a change over time) of the number of multiple accessory actuations over several time steps. According to one exemplary embodiment, the accessory actuation trend is represented as a running total of the number of multiple accessory actuations performed during each time step. According to a non-limiting example, the accessory actuation trend includes multiple data points, such as a first data point representing the total number of multiple accessory actuations performed on a first day and all previous days, a second data point representing the total number of the first data point and the total number of multiple accessory actuations performed on a second day, and so on for thirty days if the time step length is one day.According to another exemplary embodiment, the accessory actuation trend is represented as the number of multiple accessory actuations performed during each time step. According to a non-restrictive example, the accessory actuation trend includes multiple data points representing the number of multiple accessory actuations performed on each day for the preceding thirty days, if the time step length is one day.

[0054] According to an exemplary embodiment, the accessory actuation trend is determined using a mathematical / statistical data analysis of several actuation data sets (discussed above with respect to Block 118) stored in the media 28 of the controller 14. It should be recognized that the data analysis of the actuation data sets may include operations such as outlier detection and filtering, normalization, and / or additional data filtering or cleansing techniques. Following Block 120, the method 100 proceeds to Block 122.

[0055] In block 122, the controller 14 compares the accessory actuation trend determined in block 120 with a predefined accessory actuation threshold. Within the scope of protection of this disclosure, the predefined accessory actuation threshold includes a predefined expected accessory actuation trend. Assuming that the APM contactor 18 is used within the limits of its design boundaries, the predefined expected accessory actuation trend is an expected trend in the number of multiple accessory actuations over several time steps.

[0056] According to a non-restrictive example, the specified expected accessory actuation trend, starting, for example, from the vehicle's production date, contains fifteen accessory actuations per day if the APM contactor design limits result in a total expected daily actuation count of twenty actuations and five actuations are allocated for charging the auxiliary battery. According to another non-restrictive example, the specified expected accessory actuation trend contains multiple data points, including a first data point representing the sum of the number of accessory actuations expected on a first day and all previous days, a second data point representing the sum of the first data point and the number of accessory actuations expected on a second day (i.e., fifteen accessory actuations), and so on for thirty days if the time step length is one day.According to an exemplary embodiment, the specified expected accessory actuation trend is defined based on the design limits of the APM contactor and stored in the media 28 of the controller 14.

[0057] According to an exemplary embodiment, method 100 proceeds to block 124 ( Fig. 3 via the off-page connector 3B) if an accessory actuation trend line defined by the multiple data points of the accessory actuation trend determined in block 120 is above (i.e., greater than) an expected accessory actuation trend line defined by the multiple data points of the specified expected accessory actuation trend for at least a specified number of time steps (where the specified number is greater than or equal to zero). If the accessory actuation trend line is not above the expected accessory actuation trend line for at least the specified number of time steps, procedure 100 proceeds to block 126 ( Fig. 3 via the off-page connector 3C). According to some embodiments, a buffer quantity may also be included, such that the accessory actuation trend line must lie at least the buffer quantity above the expected accessory actuation trend line for at least the specified number of time steps in order for the method 100 to proceed to block 124.

[0058] According to one exemplary embodiment, the operations of block 122 described above are executed only after a predetermined number of time steps (e.g., thirty time steps) have elapsed, in order to allow for a larger data set for more data points in the accessory actuation trend. According to a non-restrictive example, if the predetermined number of time steps has not been reached, the method 100 restarts in block 102, and the method does not execute the operations of block 122 until the predetermined number of time steps has elapsed.

[0059] In Fig. 3 is a continuation of the schedule according to Fig. Figure 2 of Method 100 for controlling an APM contactor for a vehicle is shown. In Block 124, the controller 14 predicts a period of high actuation frequency, at least partially, based on the multiple actuation data sets (discussed above with respect to Block 118) stored in the media 28 of the controller 14. According to an exemplary embodiment, the controller 14 analyzes the multiple actuation data sets to identify a pattern of a high number of actuations within a specific time window. According to a non-restrictive example, the controller 14 identifies a pattern of a high number of actuations between 6:00 PM and 8:00 PM, Monday through Friday. Therefore, it is determined that the period of high actuation frequency begins at 6:00 PM and ends at 8:00 PM every Monday through Friday.It should be recognized that the controller 14 can use any combination of mathematical, statistical, and / or machine learning-based methods to analyze the multiple actuation data sets and identify the period of high actuation frequency. After block 124, procedure 100 continues to block 128.

[0060] If the current time in block 128 is not within the period of high actuation frequency defined in block 124, procedure 100 continues to block 130. If the current time is within the period of high actuation frequency defined in block 124, procedure 100 continues to block 132, as discussed in more detail below.

[0061] In block 130, the controller 14 controls the APM contactor 18 using a standard off-state control procedure. According to an exemplary embodiment, the standard off-state control procedure involves actuating the APM contactor 18 to the off state unless a specific request to actuate the APM contactor 18 to the on state is received in block 104. In other words, the APM contactor 18 may be actuated without restriction according to the requests received in block 104. After block 130, the procedure 100 continues to enter the ready state in block 106.

[0062] In block 132, the controller 14 actuates the APM contactor 18 to the ON state in response to the determination that the current time falls within the high-frequency period defined in block 124. According to an exemplary embodiment, the APM contactor 18 is actuated to the ON state at the beginning of the high-frequency period and to the OFF state at the end of the high-frequency period. Therefore, the APM contactor 18 remains in the ON state continuously during the high-frequency period, effectively limiting future accessory actuations and reducing the number of actuations of the APM contactor 18. Following block 132, the process 100 continues to enter the standby state in block 106.

[0063] In block 126, the controller 14 determines an overall actuation trend. Within the scope of protection of the present disclosure, the overall actuation trend is a trend (i.e., a change over time) of the number of multiple actuations over several time steps. According to one exemplary embodiment, the overall actuation trend is represented as a running total of the number of multiple actuations performed during each time step. According to a non-limiting example, the overall actuation trend includes multiple data points, such as a first data point representing the total of the number of multiple actuations performed on a first day and all previous days, a second data point representing the total of the first data point and the number of multiple actuations performed on a second day, and so on for thirty days if the time step length is one day.According to another exemplary embodiment, the overall actuation trend is represented as the number of multiple actuations performed during each time step. According to a non-restrictive example, the overall actuation trend includes multiple data points representing the number of multiple actuations performed on each day for the preceding thirty days, if the time step length is one day.

[0064] According to an exemplary embodiment, the overall actuation trend is determined using a mathematical / statistical data analysis of the multiple actuation data sets (discussed above with respect to Block 118) stored in the media 28 of the controller 14. It should be recognized that the data analysis of the actuation data sets may include operations such as outlier detection and filtering, normalization, and / or additional data filtering or cleansing techniques. Following Block 126, the method 100 proceeds to Block 134.

[0065] In block 134, the controller 14 compares the overall actuation trend determined in block 126 with a predetermined overall actuation threshold. Within the scope of protection of this disclosure, the predetermined overall actuation threshold includes a predetermined expected overall actuation trend. Assuming that the APM contactor 18 is used within the limits of the design boundaries of the APM contactor, the predetermined expected overall actuation trend is an expected trend in the number of multiple actuations over multiple time steps.

[0066] According to a non-restrictive example, the specified expected total actuation trend includes, for example, twenty accessory actuations per day, starting from the production date of vehicle 12, if the design limits of the APM contactor result in an expected total daily actuation count of twenty actuations. According to another non-restrictive example, the specified expected total actuation trend includes multiple data points, including a first data point representing the sum of the number of multiple actuations expected on a first day and all previous days, a second data point representing the sum of the first data point and the number of multiple actuations expected on a second day (i.e., twenty actuations), and so on for thirty days, if the time step length is one day.According to an exemplary embodiment, the specified expected overall actuation trend is defined based on the design limits of the APM contactor and stored in the media 28 of the controller 14.

[0067] According to an exemplary embodiment, method 100 proceeds to block 136 if an overall actuation trend line defined by the multiple data points of the overall actuation trend determined in block 126 is higher than (i.e., greater than) an expected overall actuation trend line defined by the multiple data points of the predetermined expected overall actuation trend for at least a predetermined number of time steps (where the predetermined number is greater than or equal to zero time steps). If the overall actuation trend line is not higher than the expected overall actuation trend line for at least the predetermined number of time steps, method 100 proceeds to enter the ready state in block 106.According to some embodiments, a buffer quantity may also be included, so that the total actuation trend line must be at least the buffer quantity above the expected total actuation trend line for at least the specified number of time steps in order for the procedure 100 to proceed to block 136.

[0068] In block 136, controller 14 estimates the number of auxiliary battery charging activations within the time step, as discussed in more detail below. After block 136, procedure 100 continues to block 138.

[0069] In block 138, the controller 14 compares the number of estimated auxiliary battery charging operations determined in block 136 with the number of available auxiliary battery charging operations. Within the scope of protection of this disclosure, the number of available auxiliary battery charging operations is determined at least partially based on the number of multiple accessory operations, the expected service life of the APM contactor, and the maximum number of operations of the APM contactor. If, according to a non-restrictive example, the design limits of the APM contactor result in an expected total daily number of twenty operations, and the number of multiple accessory operations performed on that day is fifteen, then the number of available auxiliary battery charging operations is five.If the number of estimated auxiliary battery charging operations is less than the number of available auxiliary battery charging operations, procedure 100 continues to block 140. If the number of estimated auxiliary battery charging operations is greater than the number of available auxiliary battery charging operations, procedure 100 continues to block 142, as discussed in more detail below.

[0070] In block 140, the controller 14 controls the APM contactor 18 using the standard off-state control procedure. According to an exemplary embodiment, the standard off-state control procedure involves actuating the APM contactor 18 to the off state unless a specific request to actuate the APM contactor 18 to the on state is received in block 104. In other words, the APM contactor 18 may be actuated without restriction according to the requests received in block 104. After block 140, the procedure 100 continues to enter the ready state in block 106.

[0071] In block 142, the controller 14 activates the APM contactor 18, effectively limiting future auxiliary battery charging cycles. Therefore, the APM contactor 18 remains permanently in the on state, thus reducing the number of cycles it requires. Following block 142, procedure 100 continues to enter the standby state in block 106.

[0072] According to one exemplary embodiment, the controller 14 repeatedly exits the standby state 106, restarting the procedure 100 in block 102. According to a non-limiting example, the controller 14 exits the standby state 106 and restarts the procedure 100 with a timer, e.g., every three hundred milliseconds.

[0073] In Fig.Figure 4 shows a flowchart of an exemplary embodiment 136a of block 136 (i.e., a method for estimating the number of auxiliary battery charging cycles within the time step). Exemplary embodiment 136a begins in block 402. In block 402, the controller 14 uses the auxiliary battery temperature sensor 30 to measure the temperature of the auxiliary battery 22. After block 402, exemplary embodiment 136a proceeds to blocks 404 and 406.

[0074] In block 404, the controller 14 determines an effective energy capacity of the auxiliary battery 22, at least partially, based on the battery temperature measured in block 402. According to an exemplary embodiment, the effective energy capacity is related to the state of health (SOH) of the auxiliary battery 22 and, consequently, to its age. The effective energy capacity is also related to the battery temperature. According to a non-limiting example, the effective capacity is inversely related to the battery temperature. To determine the effective energy capacity, the controller 14, according to an exemplary embodiment, uses a predefined lookup table stored in the media 28 of the controller 14, which stores the relationship between the battery temperature, the battery age, and the effective energy capacity.Following block 404, exemplary embodiment 136a continues to block 408, as will be discussed in more detail below.

[0075] In block 406, the controller 14 determines an estimated energy draw from the auxiliary battery 22 during the time step. Within the scope of this disclosure, the estimated energy draw is an estimated amount of energy discharged from the auxiliary battery 22 during a time step (e.g., a day). According to one non-limiting example, energy may be discharged from the auxiliary battery 22 to power the low-voltage vehicle accessories 24 and / or additional vehicle systems. According to another non-limiting example, energy may be discharged from the auxiliary battery 22 to heat the traction battery 16 and / or the auxiliary battery 22. Therefore, according to one non-limiting example, the estimated energy draw may be related to the battery temperature measured in block 402.To determine the estimated energy consumption, the controller 14, according to an exemplary embodiment, measures the current flow to / from the auxiliary battery 22, extrapolating the measurement over the length of the time step. After block 406, the exemplary embodiment 136a proceeds to block 408.

[0076] In block 408, the controller 14 determines an estimated charge cycle of the auxiliary battery 22. Within the scope of protection of the present disclosure, the estimated charge cycle is a periodic curve that estimates the timing of the charging and discharging of the auxiliary battery 22. According to an exemplary embodiment, the estimated charge cycle is characterized by a charge cycle duty cycle and a charge cycle period. The charge cycle period is the period (i.e., the inverse of the frequency) of the periodic estimated charge cycle curve. The charge cycle duty cycle indicates a percentage of the charge cycle period for which the auxiliary battery 22 is estimated to be charged.To determine the estimated charging cycle, the controller 14, according to an exemplary embodiment, estimates how often and for how long the auxiliary battery 22 needs to be charged, based on the effective energy capacity of the auxiliary battery 22 determined in block 404 and the estimated energy draw from the auxiliary battery 22 determined in block 406. After block 408, the exemplary embodiment 136a proceeds to block 410.

[0077] In Block 410, the controller 14 estimates the number of estimated auxiliary battery charging operations within the time step, at least partially based on the charging cycle duty cycle and / or the charging cycle period. According to an exemplary embodiment, the number of estimated auxiliary battery charging operations within the time step is equal to the frequency of the estimated charging cycle (i.e., the inverse of the charging cycle period) multiplied by the ratio of the time step to the charging cycle period. It should be recognized that additional methods for estimating the number of estimated auxiliary battery charging operations within the time step, at least partially based on the charging cycle duty cycle and / or the charging cycle period, are within the scope of protection of this disclosure. Following Block 410, exemplary embodiment 136a is completed, with method 100 continuing as discussed above.

[0078] System 10 and Method 100 of the present disclosure offer several advantages. Using System 10 and Method 100, the actuation of the APM contactor 18 is limited based on the design limits of the APM contactor 18, thereby mitigating premature wear or failure of the APM contactor 18. Furthermore, the limitation of the APM contactor actuations is performed dynamically based on detected periods of high usage. Long-term trends are analyzed to determine whether the actuation of the APM contactor 18 should be limited, while allowing short periods of increased usage without interrupting the occupant experience. Additionally, System 10 and Method 100 enable differentiation between actuations for the purpose of operating vehicle accessories and actuations for the purpose of charging the auxiliary battery 22.

[0079] The description in this disclosure is merely exemplary, and variations that do not deviate from the main point of this disclosure are deemed to fall within the scope of protection of this disclosure. Such variations are not to be considered a deviation from the inventive concept and the scope of protection of this disclosure.

Claims

[1] Method for controlling an APM contactor for a vehicle, the method comprising: Logging multiple actuations of the APM contactor within a time step, where the multiple actuations include multiple auxiliary battery charging actuations and multiple accessory actuations; Comparing a number of the multiple accessory actuators with a predefined accessory actuator threshold; and Restricting future APM contactor actuations in response to the finding that the number of multiple accessory actuations is greater than or equal to the specified accessory actuation threshold. [2] Method according to claim 1, wherein logging each of the multiple actuations of the APM contactor further comprises: Detecting an activation of the APM contactor; Incrementing a total actuation count variable in a non-transient memory in response to the detection of actuation of the APM contactor; Categorizing the actuation of the APM contactor in response to the detection of the actuation of the APM contactor, wherein the actuation of the APM contactor is categorized as one of several auxiliary battery charging actuations or as one of several accessory actuations; Incrementing an auxiliary battery charging actuation counter variable in the non-transient memory in response to categorizing the actuation of the APM contactor as one of the multiple auxiliary battery charging acts, wherein the auxiliary battery charging actuation counter variable stores a count of the multiple auxiliary battery charging acts; and Incrementing an accessory actuation counter variable in the non-transient memory in response to categorizing the actuation of the APM contactor as one of the multiple accessory actuations, wherein the accessory actuation counter variable stores the number of multiple accessory actuations. [3] Method according to claim 2, wherein logging each of the multiple actuations of the APM contactor further comprises: Storing an actuation record in the non-transient memory in response to the categorization of the actuation of the APM contactor, wherein the actuation record contains an actuation time and an actuation categorization. [4] Method according to claim 3, wherein restricting future activations of the APM contactor further comprises: Predictions of a period of high actuation frequency are based at least partially on multiple actuation data sets in the non-transient memory; Actuating the APM contactor into an on state at the beginning of a high actuation frequency period; and Actuating the APM contactor into an off state at one end of the high actuation frequency period, so that the APM contactor is constantly in the on state during the high actuation frequency period. [5] The method of claim 3, further comprising: Determining an overall actuation trend, where the overall actuation trend is a trend in the number of multiple actuations over multiple time steps; Comparing the overall actuation trend with a predetermined overall actuation threshold, wherein the predetermined overall actuation threshold includes a predetermined expected overall actuation trend, the predetermined expected overall actuation trend being determined at least partially based on an expected lifetime of the APM contactor and a maximum number of actuations of the APM contactor; and Restricting future accessory activations and future auxiliary battery charging activations in response to the determination that the total activation trend is greater than or equal to the specified expected total activation trend. [6] Method according to claim 3, wherein categorizing the actuation of the APM contactor further comprises: Categorizing the actuation of the APM contactor as one of several auxiliary battery charging actuations in response to the determination that the APM contactor was actuated to charge an auxiliary battery of the vehicle; and Categorizing the actuation of the APM contactor as one of several accessory actuations in response to the determination that the APM contactor was not actuated to charge the vehicle's auxiliary battery. [7] Method according to claim 1, wherein comparing the number of multiple accessory actuations with the predetermined accessory actuation threshold further comprises: Determining an accessory actuation trend, where the accessory actuation trend is a trend in the number of multiple accessory actuations over multiple time steps; Comparing the accessory actuation trend with the specified accessory actuation threshold, wherein the specified accessory actuation threshold includes a specified expected accessory actuation trend, the specified expected accessory actuation trend being determined at least partially based on an expected lifetime of the APM contactor and a maximum number of actuations of the APM contactor; and Determine, in response to the finding that the accessory actuation trend is greater than or equal to the specified expected accessory actuation trend, that the number of multiple accessory actuations is greater than or equal to the specified accessory actuation threshold. [8] The method of claim 1, further comprising: Calculating the number of available auxiliary battery charging cycles within the time step, at least partially based on the number of multiple accessory cycles, an expected lifetime of the APM contactor, and a maximum number of cycles of the APM contactor; Estimating the number of auxiliary battery charging cycles within the time step; Comparing the number of available auxiliary battery charging operations with the number of estimated auxiliary battery charging operations; and Restricting future auxiliary battery charging operations in response to the finding that the number of available auxiliary battery charging operations is less than the number of estimated auxiliary battery charging operations. [9] Method according to claim 8, wherein the estimation of the number of estimated auxiliary battery charging operations within the time step further comprises: Measuring the battery temperature of a vehicle's auxiliary battery; Determining an estimated energy draw from the auxiliary battery during the time step; Determining the effective energy capacity of the auxiliary battery, at least partially, based on the battery temperature; Determining an estimated charge cycle of the auxiliary battery, wherein the estimated charge cycle is characterized by a charge cycle duty cycle and a charge cycle period; and Estimating the number of estimated auxiliary battery charging operations within the time step, at least partially based on the charging cycle duty cycle and the charging cycle period. [10] Method according to claim 8, wherein restricting future auxiliary battery charging operations further comprises: Actuating the APM contactor into an on state, so that the APM contactor is constantly in the on state.

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