阅读说明：本技术 安全无线动力传动系统无线电装置
(Safety wireless power transmission system radio device
) 是由 本杰明·A·塔巴托夫斯基-布什
威廉·鲁斯纳克 于 2019-07-31 设计创作，主要内容包括：本公开提供了“安全无线动力传动系统无线电装置”。一种电池系统,具有：电池单元,所述电池单元包括容器；基板,所述基板安装到所述容器；以及所述基板上的电路。所述基板限定天线、微处理器、开关和收发器。所述微处理器顺序地激活所述开关以分别将所述收发器连接到所述天线以确立相对于发射器的位置,并且响应于所述位置落在预定义范围之外而阻止与所述发射器通信。(The present disclosure provides a "safe wireless driveline radio". A battery system having: a battery unit including a container; a base plate mounted to the container; and a circuit on the substrate. The substrate defines an antenna, a microprocessor, a switch, and a transceiver. The microprocessor sequentially activates the switches to respectively connect the transceiver to the antennas to establish a position relative to a transmitter and to prevent communication with the transmitter in response to the position falling outside a predefined range.)
1. A battery system, comprising:
a battery unit including a container;
a base plate mounted to the container; and
circuitry on the substrate, the circuitry defining an antenna, a microprocessor, a switch, and a transceiver, the microprocessor configured to: sequentially activating the switches to respectively connect the transceiver to the antennas to establish a position relative to a transmitter and prevent communication with the transmitter in response to the position falling outside a predefined range.
2. The battery system of claim 1, wherein the antenna is a directional antenna and is arranged on the substrate to define the apex of a triangle.
3. The battery system of claim 1, wherein the circuit further defines a timer to establish a time of flight of the signal.
4. The battery system of claim 1, wherein the transceiver is an ultra-wideband transceiver.
5. A battery system, comprising:
a battery unit including a container;
a base plate mounted to the container; and
circuitry on the substrate configured to prevent communication with a transmitter in response to a strength of a signal received by the circuitry from the transmitter indicating that a position of the transmitter relative to the circuitry falls outside of a set of predetermined positions.
6. The battery system of claim 5, wherein the circuit defines a directional antenna, a microprocessor, a switch, and a transceiver.
7. The battery system of claim 5, wherein the circuit further defines a timer.
8. The battery system of claim 6, wherein the microprocessor is configured to sequentially activate the switches to respectively connect the transceivers to the antennas.
9. The battery system of claim 6, wherein the transceiver is an ultra-wideband transceiver.
10. The battery system of claim 6, wherein the substrate is mounted to the container via a thermally conductive adhesive.
11. The battery system of claim 6, wherein the antenna is arranged on the substrate to define the apex of a triangle.
12. The battery system of claim 6, wherein the container is metal.
13. A method for a battery system, comprising:
by the circuitry mounted to the base plate of the container of the battery cell,
sequentially activating switches of the circuit to respectively connect a transceiver of the circuit to an antenna of the circuit to establish a distance from a transmitter,
allowing communication with the transmitter in response to the distance falling within a predefined range, an
Preventing communication with the transmitter in response to the distance falling outside the predefined range.
14. The method of claim 13, wherein the antenna is a directional antenna.
15. The method of claim 13, wherein the antennas are arranged on the substrate to define vertices of a triangle.
Technical Field
The present disclosure relates to battery cell systems that may communicate wirelessly with each other.
Background
Electric vehicles may include a traction battery to provide power to a traction motor for propulsion. The traction battery may be controlled according to data of the battery cells of the traction battery, such as temperature, voltage and current. Circuitry may be used to obtain this data.
Disclosure of Invention
A battery system has: a battery unit including a container; a base plate mounted to the container; and circuitry on the substrate defining an antenna, a microprocessor, a switch, and a transceiver. The microprocessor sequentially activates the switches to respectively connect the transceiver to the antennas to establish a position relative to a transmitter and to prevent communication with the transmitter in response to the position falling outside a predefined range.
A battery system has: a battery unit including a container; a base plate mounted to the container; and a circuit on the substrate. The circuit prevents communication with a transmitter in response to a strength of a signal received by the circuit from the transmitter indicating that a position of the transmitter relative to the circuit falls outside a set of predetermined positions.
A method for a battery system comprising: sequentially activating, by a circuit mounted to a substrate of a container of a battery cell, switches of the circuit to respectively connect a transceiver of the circuit to an antenna of the circuit to establish a distance from a transmitter; allowing communication with the transmitter in response to the distance falling within a predefined range; and preventing communication with the transmitter in response to the distance falling outside the predefined range.
Drawings
Fig. 1 is a schematic diagram of a battery pack having N battery cells connected in series.
Fig. 2 is a schematic view of one of the substrates of fig. 1.
Fig. 3 is a schematic diagram of the power switch, reference and cell balancing circuits of fig. 3.
Fig. 4A is a perspective view of a battery cell system.
Fig. 4B is a side cross-sectional view of a portion of the battery cell system of fig. 4A.
Fig. 5 and 6 are side views of the battery cell system.
Fig. 7 is a partial side cross-sectional view of a battery cell system.
Fig. 8 is a schematic diagram of a battery monitoring integrated circuit.
Fig. 9 is a schematic diagram of one of the pass switch circuits of fig. 8.
Fig. 10A is a partial side cross-sectional view of a battery cell system.
Fig. 10B is a top view of a portion of the battery cell system of fig. 10A.
Fig. 11 and 12 are schematic diagrams of a battery cell system.
Detailed Description
Various embodiments of the present disclosure are described herein. However, the disclosed embodiments are merely exemplary, and other embodiments may take various and alternative forms not explicitly shown or described. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention. As one of ordinary skill in the art will appreciate, various features illustrated and described with reference to any one of the figures may be combined with features illustrated in one or more other figures to produce embodiments that are not explicitly illustrated or described. The combination of features shown provides a representative embodiment of a typical application. However, various combinations and modifications of the described features, consistent with the teachings of the present disclosure, may be desired for particular applications or implementations.
Referring to fig. 1, a battery pack 10 contains a stack 12 of series-connected cells starting with the lowest cell (cell 1, 14) in the string, which cell 1, 14 is connected to cell 2, and so on up to cell N, which is the top cell in the string. Herein, N battery cells are connected in series. This is the usual arrangement of battery cells in a strong hybrid vehicle, which may be described as "Ns 1 p", meaning that the battery cell string has only one cell width or "1 p", and there are N such "1 p" cells stacked on top of each other. For example, for a strong hybrid vehicle, N may be 60, so 60s1p describes the 60 cells as being in one long series without any parallel. Now, if a string has 2 cells width or "2 p" and if there are 120 cells available and the most basic unit is 2 cells or "2 p" in parallel, then 60 sets of two cells in parallel can be stacked in series. In this case, when all 2 cells are grouped in parallel and stacked on top of each other in series (referred to as 60s2p), the resulting pack has the same voltage as 60s1p (for 60s1p, the pack voltage is the nominal cell voltage multiplied by 60), but the capacity of the pack is twice that of 60s1 p.
From a battery electronics hardware perspective, the bank arrangement of 60s1p functions the same as 60s2p, since there are still only 60 voltages to measure. The reason is that: for each of the 2 cells placed in parallel, only one voltage needs to be measured. Since there are 60 examples of 2p parallel cells stacked in series, a total of 60 voltages are measured in the entire group. A common arrangement for a battery electric vehicle may be to use a series combination of, for example, 96 voltages to be read, where each cell is 5 battery cells in parallel, which series combination would be 96s5 p. The total number of cells in this exemplary battery electric vehicle is 96 × 5 — 480 cells. It should be noted that the proposed content applies to any type of electrically powered vehicle, and that while fig. 1 specifically depicts the case of N cells in series, this approach works regardless of the "parallel" width of the stack — meaning, for example, that Ns1p has the same hardware setup as Ns5 p.
The battery pack 10 may be used in any kind of electrically powered vehicle within the scope of a mild hybrid vehicle, a value hybrid vehicle, a strong hybrid vehicle, a plug-in hybrid vehicle, a battery electric vehicle, or any other kind of vehicle that requires a traction battery that requires monitoring of individual cell voltages (although again, only one voltage need be measured for cells that are in parallel with each other). A notable feature is the presence of a small substrate 16 (which is a small circuit component) on FR4, ceramic, or some other suitable material, the small substrate 16 containing the circuitry needed to sense the voltage and temperature of the battery cell 14 and communicate this information through the RF link 18 between the substrate 16 and the central Battery Energy Control Module (BECM) 20. The RF link 18, which is implemented using radio frequency communications, may use a purely wireless medium between the substrate 16 and the central module 20 that couples energy to the receiving antenna on the BECM20 using antenna transmissions from the substrate 16, or the RF link 18 may use the medium of a high voltage bus in the battery pack 10. For example, as mentioned above, the battery cell strings 14 are connected in series strings. The (-) terminal on cell 1 may be referred to as V BOT 22, meaning the lowest potential of cell string 14. This same node is connected to the V _ BOT node of the BECM20 by wire 24. Similarly, the (+) terminal of battery cell N is connected to a node referred to as V _ TOP 26. This node is connected to the BECM20 by a wire 28 leading to the V _ TOP terminal of the BECM 20. In this manner, the BECM20 is connected to a high voltage bus from the battery cell stack 14, the battery cell stack 14 being made up of all battery cells from battery cell 1 to battery cell N. Since both the battery cell string 12 and the BECM20 are connected to the same high voltage bus 24, 28, they may use the high voltage bus 24, 28 as a medium that allows RF energy to travel from the substrate 16 (or any other substrate), through wiring connecting all of the battery cells to each other, through the high voltage bus wiring 24, 28, and to the BECM 20. The high voltage bus is a wired medium, but the wired medium may also carry RF energy from the substrate 16 (or any other substrate) to the central module 20. Indeed, for a radio frequency link between a given substrate and the central module 20, some portion of the signal energy may travel through the antenna radiation 18 and other portions of the signal energy may travel through the high voltage buses 24, 28. Thus, a system designer would arrange the RF communication circuitry on the substrate and the matching RF communication circuitry in the BECM20 in such a way that RF propagation could occur in any proportion in the wireless medium between the wired high voltage bus link from the battery cell string 14 to the V _ TOP and V _ BOT pins on the BECM20 or between the substrate 16 and the BECM 20.
It should be noted that any substrate may communicate using the RF link 18. That is, the RF communication circuitry on the substrate 16 may communicate not only with the BECM20, but also with any other substrate in the same group via RF. The same discussion above applies with respect to the possibility of using a wireless medium between two communication substrates or using a high voltage bus connecting a given two communication substrates. In practice today, each substrate may be able to best reach nearby substrates using RF links, but it may be more difficult to reach distant substrates for a variety of reasons (such as signal strength, efficiency of the RF channel between the transmitting and receiving substrates, etc.). Thus, a method known as mesh networking is employed in which the path taken by a message to proceed from one substrate to the central BECM20 may require several hops, meaning that the originating substrate sends out the message on an RF link to another nearby substrate, and the other nearby substrate forwards the message to a substrate closer to the central BECM20, and so on, until the message reaches a substrate with a superior RF link with the BECM 20. At this point, a message is sent from the last substrate in the mesh link to the central BECM 20. The process may proceed in reverse, with the central BECM20 sending messages to nearby substrates and then forwarding the messages along multiple links using the same kind of mesh networking concept until the message reaches the board addressed in the message. For a system properly set up to utilize mesh networking, there is no functional difference between the case where a given substrate has a direct RF link between itself and the central BECM20 and the case where the communication substrate should be mesh networked (where the number of hops equals the number of substrates in the battery pack 10). Now, it is contemplated that the hop limit or the number of hops a message may pass before being discarded may be set to be greater than the number of substrates in the battery pack 10. However, this approach may result in inefficient use of the RF spectrum, given that each time mesh networking is employed to transfer a message from one substrate to another, a certain amount of the available RF spectrum is used up. That is, if at a given time a substrate has an available link to the central BECM20, and it has a message addressed to the BECM20, it should preferentially send that message to the BECM20 rather than forward the message to some other substrate node that will continue to use the mesh networking mechanism and that will also continue to consume the RF spectrum. The most efficient use of the RF spectrum will occur without the need for mesh networking at all, such as in a system where each base node is always able to transmit and receive messages directly from the central BECM 20. However, since this is not always the case, the system may be configured with mesh networking capability such that if in some cases a substrate may not be able to reach the BECM20 directly through an RF link, a message may be sent to a nearby substrate to take advantage of mesh networking. This use of the mesh networking concept within the battery pack 10 is the reason that this technology may be referred to as peer battery pack sensing modules (which means that a network is formed between peer substrates to overcome any deficiencies in the RF link from a given substrate to the central BECM 20).
There are some other items worth mentioning in fig. 1. When node HV +32 is under control of BECM20, positive main contactor MC +30 connects (and disconnects) battery string 14 from the rest of the vehicle. That is, the BECM20 has a contactor drive circuit connected to the coil of the MC + contactor 30 that can open and close the MC + contactor 30 under the control of software executing in the BECM 20. In a similar manner, the negative main contactor MC-34 connects the lowest potential in the battery string 14 to the vehicle HV bus node HV-35 under the control of software executing in the BECM 20. A feature of the battery pack 10 is that the HV bus is precharged prior to closing the main contactor MC + 30. A precharge contactor PRC 36 and precharge resistor 38 are used for this HV bus precharge.
A typical contactor closing sequence that progresses the battery pack 10 from all contactor opens to connecting the HV buses 32, 35 would be to first close the MC-34 and the PRC 36 simultaneously, which would precharge the HV buses 32, 35 through the precharge resistor PRC 38. The BECM20 may monitor the voltage on the vehicle HV buses 32, 35. When this HV bus voltage is close in voltage (e.g., within 20V) to the bank voltage V _ TOP 26 relative to V _ BOT 22, the precharge succeeds and MC +30 can close. It should be noted that the BECM20 is on the vehicle CAN bus 40 and communication between the BECM20 and the rest of the vehicle occurs over the CAN bus 40. Other modules in the vehicle determine when the high voltage traction battery pack 10 needs to be connected to the HV buses 32, 35, and they send CAN messages to the BECM20 over the vehicle CAN bus 40. The BECM20 uses the vehicle CAN bus 40 to coordinate with other modules in the vehicle.
Referring to fig. 2, it is found that with respect to the lower level of detail of substrate 16, substrate 16 may be made of a suitable substrate material, such as FR4 or ceramic as mentioned above. It may be desirable to make the substrate 16 as small, reliable, and inexpensive as possible, since the vehicle bears the cost of N such substrates of N cells (in the case of a single series string, such as the Ns1p configuration). Ideally, all of the functions and circuitry depicted in FIG. 2 would be able to be contained in a single monolithic piece of silicon to reduce cost and improve reliability. However, there are many reasons that will result in a small number of components being mounted on the substrate 16. The first reason that more than one component may be required on the substrate 16 is the crystals 42 and 44. A crystal 42 (e.g., 24MHz) may be used to adjust the frequency used in the RF circuit. This 24MHz crystal can be used with a Phase Locked Loop (PLL) to double the oscillation to obtain the RF carrier frequency. If the desired RF carrier is below 24Mhz, the 24Mhz oscillation may also be subdivided via digital circuitry as needed. On the other hand, the crystal 44 (e.g., 32.768kHz) may be used as a low-power Real Time Clock (RTC). This type of crystal is known as a watch crystal and is common for circuits that require a hold time. The crystal 44 is optional in certain implementations because the processor 46 may have a built-in simple low power RC oscillator that is capable of holding time while the circuitry on the substrate 16 is asleep. The key difference between the optional table crystal 44 and the use of a built-in RC oscillator in the processor 46 is that: the watch crystal 44 is fairly accurate, e.g., + -20 PPM. This accuracy will only result in an error of about 12 seconds per week. However, if an internal RC timer within the processor 46 is used, the accuracy is about 8%. An application that requires excellent accuracy during sleep would be where the substrate 16 sleeps most of the time and wakes up at exactly the right moment to transmit data about the battery cell 1. The idea is that: all cells from 1 to N in the group will be in sleep and each cell will only wake up at the moment of the pair to transmit in the correct time slot. This approach results in the lowest current draw from each battery cell.
All power to operate the electronics on the substrate 16 comes from the battery unit 1. If the goal is to minimize current drain from the battery cell, it would be considered advantageous to minimize current draw, and sleep most of the time would achieve this. However, it is admittedly not a problem to have the system put energy into the traction battery when the electric vehicle is charging or running, and there is no particular need to minimize the current draw from the baseplate 16. For example, if the average current can be kept at 10mA or lower, this would be a typical current load on, for example, a lithium battery, as imposed by a typical battery monitoring integrated circuit. The amount of operating current draw from this type of monitoring electronics is not an issue for the system. What can be problematic for the system is the situation where the operating current varies from one cell to another. The cell balancing feature of the substrate comes into play when the current draw varies from one cell to the next.
Summarizing the concept of the optional watch crystal 44, the option of including a watch crystal would be relevant to minimizing current draw from the battery cell by having the electronics sleep for a majority of the time other than during the time that the radio in circuit block 46 is transmitting. However, many applications will be able to apply power to the substrate 16 while the battery pack 10 is in operation, and utilize the relatively accurate clock provided by the crystal 42. The crystal 42 will be utilized when the substrate 16 is emitting and therefore drawing full power.
Another alternative to the system is a precision reference voltage source contained in the cell balancing, power switching and reference circuit 48. This accurate reference voltage source is the "reference voltage source" in circuit 48. Now, some applications will require better accuracy than others. For example, strong hybrid electric vehicle applications attempt to maintain the battery cells within an operating window of, for example, 30% state of charge (SOC) to 70% SOC, and never attempt to charge the stack up to just 100% SOC. However, a plug-in vehicle will of course attempt to charge each battery cell in the pack up to exactly 100% SOC. The reason why the plug-in vehicle wants to bring each battery cell to exactly 100% SOC at the end of charging is that: in so doing, the vehicle will have maximum travel while not compromising the battery unit. In certain ranges, this is equivalent to say: the more accurate the cell voltage measurable in the function of determining the end-of-charge condition, the greater the capacity the pack may have. (alternatively, the less accurate the measured cell voltage, the greater margin that needs to be applied to the threshold voltage for determining 100% SOC for a given cell.) thus, for large strings, it may be significant to pay the price of a precision reference voltage source in the circuit 48 to produce a precision reference voltage for the substrate 16. For example, the selection of the reference voltage in circuit 48 and the accuracy of the A/D conversion (or voltage measurement function) in circuit block 46 may be specified as being able to determine the voltage of battery cell 1 within 10mV under all conditions, which is reasonably accurate for plug-in applications. It is the case that a strong hybrid electric vehicle application may be able to go well with a lower accuracy than this (e.g. + -. 100 mV). Thus, if a common hardware design is created for the substrate 16, to accommodate more accurate plug-in applications, the circuit 48 may fill the precision bandgap reference voltage source to produce a precision reference voltage that exits the block 48 and is provided for use by its voltage measurement function in the circuit block 46. However, the battery pack manufacturer may choose to depopulate the precise reference voltage source in circuit 48 so that no precise voltage is produced. This will be coordinated with software changes in the circuit block 46 so that a different, lower accuracy reference voltage source within the circuit block 46 is used instead. This option is a compromise between the cost of the substrate 16 and the need for application accuracy. In summary, the table crystal 44 may be optional depending on the application's need for time keeping accuracy in sleep (and the bandgap reference voltage source 50 in fig. 3 is optional depending on the application's need for cell voltage measurement accuracy).
Further comments may be made regarding advanced blocks in the substrate circuit. Cell 1 is the item being measured and the voltage of cell 1 is the input to block 48. Furthermore, the substrate 16 is powered by the same two nodes connected to the battery unit 1. There is a voltage Vsns which comes out of the circuit 48 and into the circuit block 46. This Vsns voltage is intended to be the same voltage as the positive lead of the battery cell 1. Vpwr coming out of the circuit 48 and entering the circuit block 46 is the power supply running the processor, radio, etc. This power supply may be (intentionally) interrupted if circuit block 46 asserts the Functional Safety Watchdog (FSWD) signal FSWD. The purpose of the FSWD is to be able to stop the supply of power in the event that it is determined that the substrate 16 is not functioning properly, which is an implementation of a complete power down of the circuit block 46. This type of complete power down is intended to restore the substrate 16 to its activated state. If the FSWD indicates a problem, then the rescue mode is to power down the processor.
The circuit block 46 contains a processor, a radio and so-called auxiliary functions. The auxiliary functions include: a/D conversion of cell voltages attached to the substrate 16 via Vsns input to the circuit block 46, a general purpose digital input/output port serving as a digital output (also referred to as CBctl) for activating a cell balancing function of the substrate 16, and FSWD. The FSWD output is operated by circuitry in the auxiliary functions designed to pulse when processor software is detected as not operating properly. This pulsing of the processor's FSWD output to the FSWD input of block 48 will cause block 48 to interrupt the power supply for a sufficient time to ensure a complete power down of the processor in circuit block 46. The block 48 is designed in such a way that: the power supply circuits (such as Vpwr and Vref) will be able to operate even if circuit block 46 fails and causes the FSWD output to be permanently asserted. The function of block 48 is arranged such that Vpwr and Vref are only turned off for a fixed duration, e.g., 100mS after the pulse on the FSWD output on circuit block 46. Thus, Vpwr provides power to operate the processor, ancillary circuits, and radio in circuit block 46. Vsns is the same potential as the battery cell 1, and the auxiliary function of the circuit block 46 is to perform a/D conversion on this voltage Vsns, which results in measurement of the battery cell voltage, which is the main function of the substrate 16. Circuit block 46 utilizes the Vref input in this a/D conversion function.
As mentioned above, the precision bandgap reference voltage source 50 in fig. 3 is optional; and if it is depopulated, the Vref signal from block 48 is inactive. When Vref is disabled, circuit block 46 is designed to automatically switch to its own internal and less accurate reference voltage source. The CBctl digital output from circuit block 46 is under the control of software running on a processor in circuit block 46. As mentioned above, the crystal 42 is used for RF communication from the circuit block 46. Crystal 42 also serves as the system clock for the processor in circuit block 46. Crystal 44 is optional and is a table crystal for a low power real time clock that maintains accurate time (if this is useful for the application) while the processor in circuit block 46 is asleep. If this feature is not required, the crystal 44 may be depopulated. The signal RFtxrx from circuit block 46 is from a radio in circuit block 46. It is a bi-directional signal that can act as a transmit signal from the radio or as an input signal to the radio. As previously mentioned, the RFtxrx signal is connected by a coupler circuit 54 to a Power Line Carrier (PLC) bus interface 56, the PLC bus interface 56 leading to the (+) cell input of the base plate 16, which is the high voltage bus of the battery pack 10; and, at the same time, RFtxrx is connected to the antenna circuit 58. This simultaneous connection to the antenna circuit 58 and the HV buses 32, 35 through the coupler circuit 54 allows a portion of the signal energy to be removed on the HV buses 32, 35 and a portion of the signal energy to exit the substrate 16 through the wireless antenna 58. Similarly, received energy may enter the substrate 16 through the HV buses 32, 35 or through the antenna 58. That is, the RF energy from block 46 is directed to coupler circuit 54. The coupler circuit 54 may then selectively direct this energy to either or both of the antenna circuit 58 and the PLC bus interface 56, which PLC bus interface 56 is a gateway that drives RF energy on the drive high voltage bus 32, 35 for communication with other substrates of other battery cells, and more generally with the vehicle. The coupler circuit 54 is frequency selective in that it can reduce the frequency content associated with the RF energy to allow it to flow to the PLC bus interface 56.
Referring to fig. 3, details of the power supply portion are disclosed. The cell input (e.g., cell 1) to the substrate 16 is attached by cell + lead 60 and cell-lead 62. Interestingly, these 2 pins are the only wired interface between the substrate 16 and the rest of the system. The only other interface to the system is wireless RF communication. A certain amount of RF energy is intended to travel through the connections 60 and 62. Further, the electric power of the operation substrate 16 is drawn from the individual battery cell and flows through the connection portion 60(+) and the connection portion 62 (-). It should be observed that node 60 or cell + is connected through current limiting resistor Rlim64 and connects Vsns, which flows towards circuit block 46 for measurement. It should be noted that the potential at node Vsns is relative to node 62, which node 62 is a ground reference voltage source for the entire substrate 16.
Node 62 is locally grounded. In general, any circuit in substrate 16 that requires a ground reference voltage source will use node cell-62. The cell balancing function of block 48 is implemented by a switch SWcb 70, which switch SWcb 70 may be implemented with an N-channel Metal Oxide Semiconductor Field Effect Transistor (MOSFET). The load resistor Rcb 72 completes the cell balancing circuit. It should be noted that if signal CBctl from circuit block 46 is active, SWcb 70 is activated, which connects Rcb 72 across battery cell 14 through connections 60, 62, thereby applying a certain amount (e.g., 8mA) of passive ohmic load. This current is referred to as the cell balancing capability of the substrate 16 and it can be easily set by adjusting the ohmic value of Rcb 72. However, the power dissipated is (Vcell ^2)/Rcb, where Vcell is the voltage of cell 14.
A control block 80 is shown which controls a path switch 82. For example, the pass switch 82 may be implemented as a P-channel MOSFET. High level details of the control block 80 are mentioned herein, which can be readily implemented by those skilled in the art. The cell voltages from connections 60, 62 are read through the connection from control block 80 to node 60. This allows the control block 80 to function when the voltage of the battery unit 1 is too low, for example by opening the pass switch 82. Likewise, control block 80 reads in the FSWD command signal from circuit block 46. This signal will be pulsed out when the circuit block 46 wants to command an instantaneous power down to perform a hardware restart of the system. However, if the FSWD 48 is stuck in an active state due to a fault, the control block 80 will turn on the pass switch 82 to allow the substrate 16 to operate. However, the processor in circuit block 46 will need to detect that the FSWD feature is not functioning. One approach is to set a digital "1" in some register that is known to take a "0" value at any time the processor is reset. When the FSWD is active, the software can ascertain whether the memory location remains 1, which means that power is never turned off and the FSWD is inoperative. When the FSWD is not functioning, diagnostics need to be set and the central module BECM20 should be notified of hardware problems. The basic features of the control block 80 are: if the cell voltage is normal and the FSWD signal is not pulsed out, control block 80 activates pass switch 82 to connect power to Vpwr and valid Vref. It should be noted that the bandgap reference voltage source 50 is arranged in conjunction with a resistor Rpu 90 (e.g. 1.8 kilo ohms) to generate the reference voltage Vref when the pass switch 82 is activated.
Referring to fig. 4A and 4B, a scheme of mounting the substrate 16 on the battery cell 14 is shown. In certain implementations, a thermally conductive material (such as thermal epoxy or SIL-PAD 76) is located between the substrate 16 and the top of the battery cell. To the extent that additional power is dissipated in the cell balancing circuits 70, 72, it is important that this heat be removed from the substrate 16 by the thermal interface 76. The container or can 78 of the cell 14 has a reasonable amount of surface area so it may be able to directly dissipate the heat generated in the cell balancing circuit 70, 72. However, if the can 78 is unable to dissipate this heat, some cooling mechanism (such as air or liquid cooling) should be contemplated to keep the battery cells 14 cool.
Substrate 16 is mounted on battery cell 14 by thermal connection 76 (e.g., thermal epoxy) to allow heat to be removed from substrate 16. The battery cells 14 need to measure their voltage and temperature and want to send data to the central BECM 20. The substrate 16 is encapsulated in a protective material and mounted on top of the can 78 of the battery cell 14. The flex cables 94, 96 are soldered to the substrate 16 and exit the packaged substrate on the opposite side. The flexible cable 94 is weld attached to a battery cell tab 98, which battery cell tab 98 is the positive terminal of the battery cell 14. The flexible cable 96 is weld attached to the cell tab 100, the cell tab 100 being the negative weld tab of the cell can 78. The flexible cable 94 is tightly secured at both ends and is adhesively connected to the battery cell can 78. Generally, the flexible cable 94 should be insulated to avoid shorting to the cell can sub-body 78. The same comments apply to the flex cable 96. It should be noted that the vent 102 of the battery cell 78 may open in the event of a fault. As such, it would not be optimal to have the substrate 16 above the vent 102. Thus, as depicted in fig. 4A, the packaged substrate 92 is arranged with the flex cables 94, 96 in a manner so as to avoid the cell vents 102. When the packaged substrate 16 is thermally mounted by the thermally conductive material 76, then the substrate 16 is at substantially the same temperature as the cell can 78, and then the on-chip thermal measurement circuitry in the processor of the circuit block 46 can directly read the cell temperature because the processor in the circuit block 46 is at substantially the same temperature as the cell can 78.
Referring again to fig. 2, different alternatives for the radios in circuit block 46 are worth discussing. It has been mentioned that RF propagation through the PLC bus interface 56 in the PLC mode may be utilized. For applications where the most robust signal path is through the medium of the high voltage bus, the frequency band that facilitates this mode of propagation is the best choice. For example, some commercial implementations with carrier frequencies between 455kHz and 30MHz are a good choice of PLC propagation modes. However, if a wireless link between nodes is applied that is more suitable for communication, then 2.4GHz is more suitable. There is no limitation on the frequency band used for RF communication, although using a frequency somewhere in the 455kHz to 2.4Ghz range will make it easier to find existing solutions from silicon manufacturing. Furthermore, the protocol used for communication is flexible according to the needs of the application. There are some existing protocols for power line carriers that may be used for applications where RF links are formed by wiring. For communication at 2.4Ghz, there are several popular alternatives, including bluetooth and ieee 802.15.4. No distinction is made herein between different available protocols. One aspect of using these communication protocols is that: they are used to create a data link from the substrate 16 to another radio transceiver to create a data link to the central BECM 20. As mentioned above, this may be implemented as a direct RF link from the substrate to the central BECM20, or the method may utilize mesh networking between peer substrates in order to create a data link to the central BECM 20.
As mentioned above, the substrate 16 is a mounting device for electronic circuits made of ceramic, FR4, or some other suitable surface for mounting silicon chips, surface mount components, and all other components specified herein. The connection from the battery unit 1 to the substrate 16 is made by means of flexible cables 94, 96 which can be soldered or soldered on either end. The PLC bus interface 56, power block 48, and coupler circuit 54 are conventional electronic circuits made of surface mount components as appropriate. Crystals 42 and 44 are typical surface mount devices. There are many alternatives for the antenna circuit 58. First, the antenna circuit 58 may be constructed from strip lines, which are traces on the substrate 16. Alternatively, a chip antenna may be utilized for a given application that may require better antenna performance. For circuit block 46, a maximum amount of flexibility is required. The implementation may be a single monolithic silicon, a Bluetooth Low Energy (BLE) radio, or an analog/digital array for performing ancillary functions. Alternatively, a bare chip low cost microprocessor may be used, as well as a separate bare chip for radio functions. The goal is to find bare chips that are commercially available for processor and radio functions and place them on substrate 16 in order to achieve the functions in the most compact and cheapest way. Ancillary functions as referenced in circuit block 46 are typically provided as peripheral features along with commercially available embedded processors.
Referring to fig. 3 and 5, the monolithic semiconductor 46 is mounted on a (metal) cell housing 78, the monolithic semiconductor 46 measures cell parameter (e.g., temperature, current, voltage, etc.) data, processes the data, and communicates (wired or wirelessly) information derived from the data off-chip. There are several mounting methods. The integrated circuit 46 may be mounted to the (ceramic) substrate 16 via solder bumps 106. Substrate 16 may then be mounted directly to cell housing 78 via thermally conductive adhesive 76 or via metal tabs deposited on the underside of substrate 16.
The thermal adhesive use case is the case when no electrical connection from the housing 78 to the substrate 16 is required. Here, the monolithic integrated circuit 46 needs to be mounted to the cell can 78 through a thermal connection. The block 46 is mounted on the substrate 16. The substrate 16 is metallized on the top side (the side facing the blocks 46) by a conductive material such as copper, aluminum, or the like. This metallization layer on the top side of the substrate 16 may be patterned via photolithographic techniques to form traces and pads 112, and chips may be mounted on and connected to the traces and pads 112. Two techniques for forming the node connections are solder bumps 106 on the underside of the bumps 46 or bond pads on the topside of the bumps 46 that can be wire bonded to conductive traces on the substrate 16. Block 114 represents any additional components required in the circuit, such as crystals, transistor switches, or other components, along with monolithic integrated circuit 46 (see fig. 2).
Referring to fig. 6, a conductive adhesive mount is shown. This use case is the case when it is desired to make an electrical connection from the metal housing 78 to the substrate 16'. An additional metallization layer 116 is added to the bottom side of the substrate 16'. In addition, one or more vias 118 extend from the metallization layer 116 to the traces or circuits 112 on the top side of the substrate 16'. Here, the monolithic integrated circuit 46 needs to be mounted to the battery cell can 78 by an electrical and thermal connection 120. The substrate 16' may be prefabricated with a metallization layer 112 on the top and a metallization layer 116 on the bottom, the metallization layers 112 and 116 being suitably patterned before being used to mount circuitry and connect to the cell can 78. Herein, the layer 120 is an adhesive that is thermally and electrically conductive, for example, by appropriately sized suspended carbon particles in the adhesive.
Referring to fig. 7, a direct chip mounting technique is shown. The basic concept is to mount the monolithic integrated circuit 46 directly to the metal cell can 78 via a thermally conductive adhesive 122. Here, chip 46 is connected to cell tabs 98, 100. This will be done via wire bonds 124, 125. However, the wire bonds 124, 125 need to be close to the target of the chip 46 so they can be soldered on one end to the pads 126 on the integrated circuit 46; and on the other side to respective metal pads 128, 130 on the flexible printed circuits 94, 96. As mentioned above, the positive weld tab 98 on the cell can 78 is joined to the flexible printed circuit 94 via a weld or solder joint. The flexible printed circuit 94 is a flexible circuit trace that is adhesively connected to the battery cell can 78. The flexible printed circuit 94 has conductive traces on its inside, but this conductive trace is surrounded by an insulating material so that there is no electrical connection made from the conductive trace to the metal can 78. Thus, the node of the positive solder tab 98 is connected to the flexible printed circuit 94, and it carries the signal to a point near the integrated circuit 46. The flexible printed circuit 94 has openings that expose this inner metal layer to which the wire bonds 124 are soldered or welded at pads 128. Similarly, the negative welding tab 100 of the battery cell can 78 is connected to the flexible printed circuit 96 via a weld or braze joint. The flexible printed circuit 96 connects the negative battery cell terminal to a point near the monolithic integrated circuit 46. Wire bonds 125 connect pads 126 to pads 130 and this completes the electrical connection of integrated circuit 46 to cell terminals 98, 100. The thermal adhesive 122 forms a good thermal connection from the block 46 to the can 78, but electrical insulation from the block 46 to the can 78 is desired. The adhesive 122 is not conductive.
Referring again to fig. 3 and 4, the traction battery pack 10 includes: a battery monitoring circuit 46, the battery monitoring circuit 46 measuring a voltage, a temperature, and the like of the individual battery cells (which exclusively supply power to the monitoring circuit 46); and a front-end path switch 82 (a path switch positioned between the battery cell and the monitoring circuitry), the front-end path switch 82 disconnecting power to the monitoring circuitry 46 under certain conditions, such as low battery cell voltage, or a problem that can be detected by a safety monitor that may be implemented in software or hardware. Examples of safety monitoring include monitoring for over-voltage, over-current, over-temperature, proper operation of a safety monitor, and the like. The associated predefined threshold may be established by, for example, testing or simulation. Exceeding these thresholds will cause the pass switch 82 to open.
Referring to fig. 8, the pass switch concept is also applicable to conventional battery monitoring integrated circuits. Herein, implementations of conventional Battery Monitoring Integrated Circuits (BMICs) 136, 138 applying the proposed path switch are found. That is, the pass switch concept is applied to BMIC technology. This is used in a traction battery pack comprising battery cells 140, 142 arranged in a string from VC1 to VCmm. There are one or more BMICs 136, 138 that monitor the cells and communicate cell voltage readings back to the central controller. A block 144, which is a pass switch circuit, is inserted between the top cell in the sub-string and the Vdd pin of the BMIC 136. In this example, a string of 12 cells with cell 140 at the bottom and cell 142 at the top, or cells VC 1-VC 12, is used to power the BMIC136, where the reference voltage source for the Vss pin of the BMIC136 is connected to the V _ BOT, which is the negative terminal on the cell 140, and the power supply connection or Vdd pin of the BMIC136 is connected to the pass switch circuit. Here, it is seen that the path switch circuit 144 opens and closes connections from the substrings VC1 to VC12 to the power supply pins or Vdd of the BMIC 136. That is, pass switch circuit 144 may disconnect power from BMIC 136. Also in this example, each BMIC in the stack (e.g., BMIC 138) is accompanied by a similar pass switch circuit.
It should be noted that the path switch circuit 144 may be reminiscent of the power switch circuit 82 in fig. 3. However, it is not the same. This is because the path switch circuit 82 is optimized for single cell battery pack sensing module peer-to-peer applications. The path switch circuit 144 is optimized for use with the BMICs 136, 138.
Referring to fig. 9, the power input connection to block 144 is through DC _ IN + 148. This corresponds to the positive terminal of the battery cell 142(VC 12). Vlocal1150 is also seen to be connected to the negative pin (VC1/V _ BOT) on battery cell 140VC1, which is herein the lowest potential in the entire string of battery cells VC1 to VCmm. The power supply for the channel block enters via DC _ IN +148 and Vlocal 1150. Vlocal1150 is a reference voltage source or local ground, and DC _ IN +148 is the combined power and measurement point for the node at the top of battery cell 142(VC 12). The DC _ IN + node 148 is connected to pass transistor 152 IN block 144. Switch 152 is controlled by control block 154. Control block 154 measures the voltage of DC _ IN + 148. Control block 154 uses this voltage to decide to open path switch 152 if: the voltage DC _ IN +148 drops below a certain voltage, e.g., 1.0 volts/cell. Thus, for 12 cells VC 1-VC 12, 1.0 volts per cell 12 cells — 12V. This makes it possible to open the pass switch 152 when a group of 12 cells VC 1-VC 12 falls below an average voltage of 1V per cell. The reason why it may be desirable to do so is that BMIC 144 is likely to over-discharge the battery cells to obtain its own power when the battery cells are so low. Therefore, it is an excellent protection feature for control block 154 to command pass switch 152 to protect the battery cells from over-discharge when the voltage of DC _ IN +148 compared to Vlocal1150 drops below, for example, 12V. There are certain modes of BMIC136 that result from problems during manufacturing or from the use of over-electrical stress in BMIC136, which can cause excessive current draw on the Vdd (power supply) pin of BMIC 136. In this case, in order to prevent the problem of the cell strings VC1 to VC12, the BMIC136 is disconnected using the path switch circuit 152. This therefore provides great utility by protecting the battery cells and allowing replacement of the electronics module containing the BMIC 136.
FSWD is a control input to control block 154. This FSWD is shown herein as a common signal connected to several pass switch circuits (such as 144, 146). This may be implemented as an interface signal that is common and capable of driving a signal into each of the control blocks. For example, the signal referenced to Vlocal1150 (also referred to as V _ BOT) can be connected to all control blocks through high impedance or even through opto-electrical isolation in each control block to prevent interaction between the different control blocks. The FSWD may be connected to a central control module (such as the BECM) so that in the event of a battery pack safety state event, it may choose to disconnect all BMICs by opening all pass switches. This is done via the FSWD signal. When the system is in a normal state, the central module may send heartbeat messages on the FSWD signal. However, when the central module does not send the appropriate heartbeat signal, the control block will then open the path switch. In this way, a reliable method of causing the BMIC to stop drawing power from the battery cell in the event of a safe state event is achieved.
Furthermore, the control block may be arranged to open the pass switch in the event of any desired fault event. So far, the use of control block 154 to open pass switch 152 IN the event of undervoltage on DC _ IN +148 and loss of the heartbeat signal on FSWD has been described. However, there may be any number of other signals that control block 154 may decide to monitor for opening of pass switch 152, such as the temperature of the circuit through an internal thermistor located in control block 154, or by monitoring the current through pass switch 152 through a drop in Vds through a measurement transistor (not shown), or any other suitable means of noticing some error in the circuit.
Referring to fig. 10A and 10B, flexible leads 94, 96 (e.g., flexible flat metal conductors represented by hatched lines surrounded by a dimensionally controlled insulating material represented by hatched outline lines having an adhesive on one side) are attached directly to the cell can 78 so that the assembly of flexible leads 94, 96 and the attached ground plane can exhibit controlled impedance characteristics. In addition, the proximity of the flat metal conductors with respect to the attached ground plane provides electromagnetic shielding for the flexible leads. Thus, the arrangement creates a low Z connection from the substrate 16 to the cell solder tabs 98, 100 and shielding of the signal from the solder tabs 98, 100 to the substrate 16, which can help obtain a low noise, accurate reading from the cell 14.
The two wire bonds 156, 157 are connected to a node on the block 46, which is the reference voltage source or ground of the transmitter circuit. Wire bond 158 is a node connected to battery cell + 98. The wire bonding part 160 is a node connected to the battery cell-100. The ground plane 162 is lower than the positive signal. It should be noted that the ground plane 162 is implemented in a conductor layer of the flexible printed circuit 94. The traces on top of the flexible printed circuit 94 are connected only to the positive battery cell terminal 98 and are insulated from the ground reference voltage source 162. The ground plane 166 is the layer below the flexible printed circuit 96. The signal layer in the flexible printed circuit 96 connects the wire bonds 160 from the cell connections on the integrated circuit 46 to the cell tabs 100.
A thermal adhesive layer 122 separates the block 46 from the cell can 78. It also insulates the flexible printed circuits 94, 96 and ground planes 162, 166 and prevents any connection from it to the cell can 78: they are insulated from the can 78. It should be noted that the ground planes 162, 166 are connected to each other by their connection to the ground reference voltage source of the block 46 via the wire bonds 156, 157, but the flex circuit 94 is not electrically connected to the flex circuit 96. Thus, a stripline antenna having controlled impedance characteristics is formed. Which can be used to transmit RF out of the circuit 46 through the dipole formed by the flex circuits 94, 96. The ground planes 162, 166 are part of a dipole antenna circuit. The ground plane 162 and the flexible printed circuit 94 form a stripline antenna, as do the ground plane 166 and the flexible printed circuit 96.
Security may be a consideration in wireless applications, such as those described herein. One security area is to identify trusted agents that may communicate with other wireless nodes in the powertrain. One approach is to measure the physical location of the radio in communication with the BECM radio. This ensures the security of the link if the BECM communicates over a wireless link and it measures that the transceiver on the other end is within the battery pack 10. If the BECM measures that the transceiver is outside of the battery pack 10, then it may choose not to communicate with it at all. Since networking with the vehicle is performed by means other than wireless networking as described herein, any communication requests originating from outside the battery pack 10 may be ignored. It may be reasonable to assume that a hostile agent will not be able to position a transceiver within the high voltage battery pack 10 because it is mechanically sealed and the agent will need to physically enter the vehicle.
Wireless circuitry implementing two wireless security zones is contemplated. Here, a circuit that detects the physical location of the radio device with which communication is being performed is added to the above wireless section. That is, the transmitter may ascertain the location of the receiver in space through several techniques. It is disclosed how to measure the distance from the transmitter to the receiver, how to measure the azimuth angle theta, and how to measure the azimuth angle phi. Starting from a point in three-dimensional space, the specification of the distance R, the azimuth angle θ, and the azimuth angle Φ uniquely fixes the position of the receiver in space. In one example, this is performed using a particular wireless technology known as Ultra-Wideband (UWB). The same concepts are applicable to other kinds of wireless technologies.
The underlying circuit features include the ability to measure distance, and the ability to measure azimuth angle θ and azimuth angle φ. The multiple antenna method may be used to measure range, for example by measuring the average signal strength of a received signal of known transmit power over all diversity antennas, thereby providing an R parameter. To calculate the theta and phi parameters, the signal strengths at the different diversity antennas are compared and a geometric calculation is performed to fix the position in space. Further, a technique for specifically using the ultra-wideband feature will be shown later.
Systems similar to those described in the previous figures should be considered: a plurality of battery cells, each battery cell having a substrate containing a processor and a wireless transceiver and one or more RF paths to advance RF signals from the wireless transceiver to an antenna. Referring to fig. 11, a single UWB transceiver 168 has a transmit receive port (TXRX) that selectively transmits or receives UWB pulses. As known to those skilled in the art, UWB transmit pulses are well-defined in time, and the time at which a pulse is received can be accurately measured by the receiver using a high resolution timer 170, which high resolution timer 170 measures, for example, to nanosecond accuracy. When the transmitter (e.g., circuitry that desires to communicate with the microprocessor 174) and the receiver have synchronized their timers using known techniques, such as those described in U.S. patent No. 9,217,781, they may be arranged so that the transmitter sends a pulse at the appointed time, and then the receiver measures the value of the high-accuracy timer at the time the pulse is received. By this mechanism, the time of flight of the pulse can be accurately measured. Since the velocity of the electromagnetic wave is known, the distance from the transmitter to the receiver can be measured within a few centimeters. It should be noted that fig. 1 shows three direction sensitive antennas 174, 176, 178. Switches 180, 182, 184, respectively, may be used to select each of the three antennas one at a time. The distances Da, Db, and Dc from each of the antennas 174, 176, 178 may be measured separately. The estimated distance between the transmitter and the receiver may be calculated as (Da + Db + Dc)/3. Referring to fig. 2, each of these antennas 174, 176, 178 is located in a well-defined location on the surface of the substrate 16; and they are arranged as isosceles triangles. This shape will enable the use of known geometries and signal measurements in order to fix the position of the receiver in three-dimensional space.
Since the distance from the transmitter to the receiver is now known, two further parameters are required to fix the position of the receiver in space relative to the transmitter. This would be the angles theta and phi because, given the reference point of the transmitter, only the radius and two angles need to be known to characterize the position in three dimensions. The switch 180 is first closed by control from the microprocessor 172 while the switches 182, 184 are open. This connects the directional antenna 174 to the UWB transceiver 168. As is well known to those skilled in the art, the signal strength is measured using a Received Signal Strength Indicator (RSSI) at transceiver 168 as RSSI _ a. The switch 182 is then closed while the switches 180, 184 are open, which now connects the directional antenna 176 to the transceiver 168. Again, the signal strength RSSI _ B is measured using the RSSI at the transceiver. Then, the switch 184 is closed while the switches 180, 182 are open, and the signal strength RSSI _ C is measured. The angle θ from 0 to 180 degrees is determined as the ratio of the two measured signal strengths between RSSI _ B and RSSI _ C as follows:
θ (in radians) — (pi/2) + K1 — (RSSI _ B-RSSI _ C), where K1 is a calibration constant.
If RSSI _ B is equal to RSSI _ C, the transmitter distances are equidistant from both, and since the antennas are directional, it is known that the position must lie on a line perpendicular to the line connecting the centers of the two directional antennas. If they are different, they must differ by an amount proportional to the closer the transmitter is to one of the two directional antennas; and therefore, by multiplying this difference by the correct scale factor, this provides an angle that is different from the centerline.
Similarly, the angle φ from 0 to pi/4 can be calculated as a function of RSSI _ A and the average of RSSI _ B and RSSI _ C:
RSSI _ BCavg ═ absolute value [ (RSSI _ B-RSSI _ C)/2) ]
Phi (in radians) — (pi/4) + K1 (RSSI _ a-RSSI _ BCavg), where K2 is a calibration constant.
Thus, the distance R, direction θ, and azimuth φ from the transmitter to the receiver are now known. Any undesired party wishing to communicate with the system via a transceiver will necessarily have a different triplet R, theta, phi, since they are necessarily outside the battery box. It should therefore be noted that the transmitter will refuse to communicate with a radio outside the battery box; and similarly the receiver will refuse to communicate with a transmitter outside the battery box. That is, the microprocessor 172 will prevent further communication with another device whose location falls outside of the expected range within the battery box and allow further communication with another device whose location falls within the expected range. This will ensure wireless security.
The processes, methods, or algorithms disclosed herein may be capable of being delivered to/implemented by a processing device, controller, or computer, which may include any existing programmable or dedicated electronic control unit. Similarly, the processes, methods or algorithms may be stored as data and instructions that are executable by a controller or computer in a number of forms, including, but not limited to: information permanently stored on non-writable storage media (such as read-only memory (ROM) devices); and information alterably stored on writable storage media such as floppy disks, magnetic tape, Compact Disks (CDs), Random Access Memory (RAM) devices, and other magnetic and optical media. The processes, methods, or algorithms may also be implemented in software executable objects. Alternatively, the processes, methods or algorithms may be implemented in whole or in part using suitable hardware components, such as Application Specific Integrated Circuits (ASICs), Field Programmable Gate Arrays (FPGAs), state machines, controllers or other hardware components or devices, or a combination of hardware, software and firmware components.
The words 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 and claims. Some arrangements, for example, need not include the timer 170: only a measure of received signal strength may be used to determine the relative position between the transmitter and receiver, etc., as is known in the art. Other arrangements are also contemplated.
As previously mentioned, features of the various embodiments may be combined to form further embodiments that may not be explicitly described or illustrated. Although various embodiments may be described as providing advantages or being preferred over other embodiments or prior art implementations with respect to one or more desired characteristics, those of ordinary skill in the art will recognize that one or more features or characteristics may be compromised to achieve desired overall system attributes, which depend on the specific application and implementation. These attributes include, but are not limited to: cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, serviceability, weight, manufacturability, ease of assembly, and the like. Accordingly, embodiments described as less desirable with respect to one or more characteristics than other embodiments or prior art implementations are within the scope of the present disclosure and may be desirable for particular applications.
In one aspect of the invention, the substrate is mounted to the container via a thermally conductive adhesive.
According to one embodiment, the container is metal.
According to one embodiment, the container is a metal can.
