The disclosure relates generally to determination of fuse life for a fuse element, and more specifically, to determination of remaining fuse life in a vehicle.
Electric, hybrid, fuel cell and many other types of vehicles use battery packs as a source of electrical energy for driving the vehicles. These vehicles employ a fuse system to provide an automatic interruption of power in the event of excessive current flow.
A fuse system includes a fuse element configured to receive a current. A controller is operatively connected to the fuse element and has a processor and tangible, non-transitory memory on which is recorded instructions for executing a method for determining a remaining fuse life (L) of the fuse element. Execution of the instructions by the processor causes the controller to determine at least one temperature (T) of the fuse element. The remaining fuse life (L) and temperature (T) vary over time t.
Determining the temperature (T) of the fuse element may include: determining the current (I) received by the fuse element; and converting the current (I) to the temperature (T), based at least partially on a resistance (R) and heat capacity (CP) of the fuse element, an ambient temperature (TA) and other factors.
One or more temperature sensors may be operatively connected to respective zones of the fuse element and configured to provide respective temperature readings for the respective zones. Determining the temperature (T) of the fuse element may include: obtaining the respective temperature readings from the one or more temperature sensors; and obtaining the temperature (T) of the fuse element as a weighted average of the respective temperature readings.
The controller may obtain multiple values of the temperature (T) and obtain a weighted value of the temperature (T), using respective weighting factors. The controller may be configured to convert the temperature (T) of the fuse element to a strain value (S). The controller may be configured to convert the strain value (S) to a used fuse life (U). The controller may be configured to convert the used fuse life (U) to the remaining fuse life (L).
The controller may be deactivated at an initial time from a first wake cycle and then activated after a key-off time duration (t0) from the initial time. The controller may be configured to obtain a last-known temperature delta of the fuse element, where the last-known temperature delta is the last-known temperature difference from the first wake cycle between the fuse element and the ambient temperature. The controller may be configured to determine a correction factor (CF) based at least partially on the key-off time duration (t0) and a predefined constant (τ). The correction factor (CF) may be defined as the exponential of the negative of the key-off time duration (to) divided by a predefined constant (τ) [CF=e(−t0/τ)].
The fuse system may be part of a vehicle. The vehicle may include at least one battery component configured to store energy and be operatively connected to the fuse element. The controller may be configured to determine if the remaining fuse life is below a first threshold. If the remaining fuse life is below the first threshold, the controller determines if the remaining fuse life is below a second threshold. In one example, the first threshold is 20% life remaining and the second threshold is 5% life remaining.
If the remaining fuse life is above the second threshold (and below the first threshold), a first message may be displayed to the vehicle display. If the remaining fuse life is below the second threshold, the vehicle may be shifted to a predefined alternative operating mode. The predefined alternative operating mode is configured to limit the current received by the fuse element.
The above features and advantages and other features and advantages of the present disclosure are readily apparent from the following detailed description of the best modes for carrying out the disclosure when taken in connection with the accompanying drawings.
Referring to the Figures, wherein like reference numbers refer to the same or similar components throughout the several views,
Referring to
Referring to
Referring to
The fuse element 14 may include one or more zones, each with a respective temperature sensor. In the embodiment shown in
Referring now to
Referring to
If the controller 30 is not initializing, the method 100 proceeds to step 104, as indicated by line 103. In step 104, the controller 30 is configured to determine the temperature (T) of the fuse element. Step 104 may be accomplished by sub-step 105 alone, sub-step 106 alone or a combination of sub-steps 105 and 106.
Sub-step 105 includes determining the current (I) received by the fuse element 14 via the current-measuring device and then converting the current (I) to the temperature (T). The current (I) is converted to the temperature (T) based at least partially on a resistance (R) and heat capacity (CP) of the fuse element 14, a last-known temperature (TL), a heat transfer coefficient k and an ambient temperature (TA). In one embodiment, the temperature (T) is defined as:
T(t)=∫0t(I2(t)*R−k(TL−TA))dt/CP.
Here, k represents a heat transfer coefficient for calculating heat lost to the ambient temperature. The heat transfer coefficient k may be generated for a particular system using calculations or a lookup table. In one example, the heat transfer coefficient k is assumed to be a constant and calculated based on the vertical and horizontal surface area of the fuse element 14, the general shape of the housing (not shown) that the fuse element 14 resides in, the surface temperature of the fuse element 14 and other factors. The fuse element 14 may be broken down into multiple surfaces each having its own surface temperature and heat transfer coefficient. In another example, the heat transfer coefficient k is assumed to vary based on the degree of temperature difference between the surface temperature of the fuse element 14 and ambient temperature (TA). In this case, the heat transfer coefficient k may be in the form of a lookup table or in the form of an equation. The method 100 may include multiple heat transfer coefficients in the temperature approximation, such as a heat transfer coefficient that is applied to the fuse body temperature instead of directly on the fuse element 14. Additional coefficients may be applied directly to the fuse element 14 in order to approximate heat flowing from the elements into the material that is used to fill the void between the elements and into the fuse body/copper cables (not shown).
Referring to
The controller 30 may obtain repeat step 104 to obtain multiple values of the temperature and use a weighted value (obtained with respective weighting factors) of the temperature (T) in step 108. In one example, the controller 30 repeats step 104 twice and uses the average value of the temperature (T=0.5 T1+0.5 T2) in step 108, providing a more robust determination. In step 108 of
In step 110 of
The used fuse life (U) at time (tn) may be defined as the absolute value of the difference in inverse cycles to failure values at times (tn) and (tn-1) (illustrated in the example below):
U(tn)=|1/C(tn)−1/C(tn-1)|.
In step 112 of
L(tn)=L(tn-1)−U(tn).
A numerical non-limiting example based on
U(t1)=|1/C(10% strain)|=(1/(200 cycles to failure)=0.5%.
L(t1)=L(t0)−U(t1)=100%−0.5%=99.5%
The used fuse life and remaining fuse life at time t2 may be calculated as follows:
U(t2)=|1/C(5% strain)−1/C(10% strain)|=|1/(500 cycles to failure)−1/(200 cycles to failure)|=10.2%−0.5%)|=0.3%.
L(t2)=L(t1)−U(t2)=99.5%−0.3%=99.2%
The used fuse life and remaining fuse life at time t3 may be calculated as follows:
U(t3)=|1/C(15% strain)−1/C(5% strain)|=|1/(100 cycles to failure)−1/(500 cycles to failure)|=|1%−0.2%)|=0.8%.
L(t3)=L(t2)−U(t3)=99.2%−0.8%=98.4%.
In step 114, the controller 30 is configured to determine if the remaining fuse life is below a first threshold (L<X). In one example, the first threshold is 20% life remaining. If the remaining fuse life (L) is below the first threshold, the method 100 proceeds to step 116. If the remaining fuse life (L) is above the first threshold, the method 100 may loop back to step 104.
In step 116 of
If the remaining fuse life is below the second threshold, method 100 proceeds to step 120 in which the controller 30 is configured to shift to a predefined alternative operating mode (indicated as “A” in
The remaining fuse life (L) may be converted to a mileage counter that is specific to a particular vehicle/driver, e.g miles remaining fuse life (M). For example, if 50% remaining fuse life (L=50%) occurred for a first vehicle/driver at an odometer reading of 10,000 miles, this would indicate that the first vehicle/driver A had 10,000 miles left in remaining fuse life (M=10,000 miles). If 50% remaining fuse life (L=50%) occurred for a second vehicle/driver at an odometer reading of 20,000 miles, this would indicate that the second vehicle/driver had 20,000 miles left in remaining fuse life (M=20,000 miles).
Referring back to step 102, if the controller 30 is initializing, the method 100 may proceed to step 122, as indicated by line 121. In step 122 of
In step 124 of
The corrected temperature delta (ΔT) of the fuse element 14 is defined as a product of the last-known temperature delta (ΔT1) of the fuse element 14 multiplied by the correction factor (CF). The correction factor (CF) is based at least partially on the key-off time duration (t0) and a predefined constant (τ). In the embodiment shown, the correction factor (CF) is defined as the exponential of the negative of the key-off time duration (to) divided by a predefined constant (τ) [CF=e(−t0/τ)], where e is Euler's number. Thus the corrected temperature delta (ΔT) may be defined as (where TL1 is the uncorrected last-known temperature and TA1 is the uncorrected ambient temperature):
(ΔT)=(ΔT1)*CF=(TL1−TA1)*e(−t0/τ).
The time constant to may be calculated by measuring the temperature decay of the fuse element 14 after key-off and fitting the function [e(−t0/τ)] to the measured results. In another example, the time constant to is calculated using the thermal capacity, thermal resistivity, surface area, and heat transfer coefficient to calculate an approximate temperature in lieu of physical temperature measurements. Alternatively, the time constant to may be calculated by employing thermal and/or computational fluid dynamics 2D/3D simulations in lieu of physical temperature measurements.
As noted above, the controller 30 of
A computer-readable medium (also referred to as a processor-readable medium) includes any non-transitory (e.g., tangible) medium that participates in providing data (e.g., instructions) that may be read by a computer (e.g., by a processor of a computer). Such a medium may take many forms, including, but not limited to, non-volatile media and volatile media. Non-volatile media may include, for example, optical or magnetic disks and other persistent memory. Volatile media may include, for example, dynamic random access memory (DRAM), which may constitute a main memory. Such instructions may be transmitted by one or more transmission media, including coaxial cables, copper wire and fiber optics, including the wires that comprise a system bus coupled to a processor of a computer. Some forms of computer-readable media include, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD, any other optical medium, punch cards, paper tape, any other physical medium with patterns of holes, a RAM, a PROM, an EPROM, a FLASH-EEPROM, any other memory chip or cartridge, or any other medium from which a computer can read.
Look-up tables, databases, data repositories or other data stores described herein may include various kinds of mechanisms for storing, accessing, and retrieving various kinds of data, including a hierarchical database, a set of files in a file system, an application database in a proprietary format, a relational database management system (RDBMS), etc. Each such data store may be included within a computing device employing a computer operating system such as one of those mentioned above, and may be accessed via a network in any one or more of a variety of manners. A file system may be accessible from a computer operating system, and may include files stored in various formats. An RDBMS may employ the Structured Query Language (SQL) in addition to a language for creating, storing, editing, and executing stored procedures, such as the PL/SQL language mentioned above.
The detailed description and the drawings or figures are supportive and descriptive of the disclosure, but the scope of the disclosure is defined solely by the claims. While some of the best modes and other embodiments for carrying out the claimed disclosure have been described in detail, various alternative designs and embodiments exist for practicing the disclosure defined in the appended claims. Furthermore, the embodiments shown in the drawings or the characteristics of various embodiments mentioned in the present description are not necessarily to be understood as embodiments independent of each other. Rather, it is possible that each of the characteristics described in one of the examples of an embodiment can be combined with one or a plurality of other desired characteristics from other embodiments, resulting in other embodiments not described in words or by reference to the drawings. Accordingly, such other embodiments fall within the framework of the scope of the appended claims.
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