Thermal management of battery cell tab temperature

Abstract

A vehicle includes a system that operates a method of controlling a temperature of a vehicle cell. The system includes a battery cell, a temperature sensor, and a processor. The battery cell has a tab for current to flow into and out of the battery cell. The temperature sensor is configured to measure a cell temperature of the battery cell at a location that is remote from the tab. The processor is configured to predict a tab temperature from the cell temperature and control power provided from the battery cell to a load based on the tab temperature.

Description

Technical Field

[0001] This article relates to the control of battery cell temperature, and more specifically to a system and method for controlling the operation of battery cells based on the calculated temperature at the cell's junction. Background Technology

[0002] Electric vehicles draw power from battery packs that house multiple battery cells. Each battery cell includes a contact plate through which current flows in and out. The current or power passing through a battery cell can raise its temperature above a safe operating temperature. Due to the size of the contact plate, it is most likely to reach this safe threshold temperature before any other component. Unfortunately, due to design and packaging considerations, it is difficult to place a sensor directly on the contact plate to measure its temperature. Therefore, it is desirable to provide a method for determining the contact plate temperature based on other temperature measurements available from the battery cell. Summary of the Invention

[0003] In one exemplary embodiment, a method for controlling the temperature of a control unit is disclosed. The cell temperature is measured at a battery cell, the battery cell including contacts for current flow into and out of the battery cell, wherein the cell temperature is obtained at a location remote from the contacts. The contact temperature of the contacts is predicted based on the cell temperature. The power supplied from the battery cell to a load is controlled based on the contact temperature.

[0004] In addition to one or more features described herein, the battery cell is included in the battery module, and obtaining the cell temperature also includes obtaining one of the following: the highest and lowest temperatures of the battery cell at a location in the battery module separate from the battery cell, and the average temperature of the battery cell. The method also includes predicting the contact temperature using a dynamic thermodynamic model of the heat exchange process around the cell contacts and current busbars based on the current and cell temperature at the battery cell. In one embodiment, the contact is in thermal contact with the busbar, and the busbar is in thermal contact with the heat sink, and the dynamic thermodynamic model determines the state of the battery cell based on the heating of the contact, busbar, and heat sink caused by the current flowing through the contact. A Kalman filter is applied to the state of the battery cell determined using the dynamic thermodynamic model to determine the contact temperature. The method also includes reducing the power supplied to the load when the contact temperature is greater than or equal to a temperature limit. The load is at least one of the vehicle's electric motor and electrical components of the vehicle.

[0005] In another exemplary embodiment, a system for controlling the temperature of a battery cell is disclosed. The system includes a temperature sensor and a processor. The temperature sensor is configured to measure the cell temperature at the battery cell, which includes contacts for current flow into and out of the cell, wherein the temperature sensor is located remotely from the contacts. The processor is configured to predict the contact temperature of the contacts based on the cell temperature and to control the power supplied from the battery cell to a load based on the contact temperature.

[0006] In addition to one or more features described herein, the battery cells are included in the battery module, and the temperature sensor includes one of the following: a maximum temperature sensor for measuring the highest temperature of the battery module, a minimum temperature sensor for measuring the lowest temperature of the battery module, and an average temperature sensor for measuring the average temperature of the battery cells. The processor is also configured to predict the contact temperature based on the current and cell temperature of the battery cells using a dynamic thermodynamic model of the battery cells. In one embodiment, the contact is in thermal contact with a busbar, and the busbar is in thermal contact with a heat sink, and the processor is further configured to use a dynamic thermodynamic model to determine the state of the battery cells based on heating of the contact, busbar, and heat sink due to current flowing through the contact. The processor is also configured to apply a Kalman filter to the state of the battery cells determined using the dynamic thermodynamic model to determine the contact temperature. The processor is also configured to reduce the power supplied to the load when the contact temperature is greater than or equal to a temperature limit. The processor is also configured to reduce power based on a maximum permissible battery current limit based on a temperature limit and the dynamic thermodynamic model of the battery cells.

[0007] In yet another exemplary embodiment, a vehicle is disclosed. The vehicle includes a battery cell, a temperature sensor, and a processor. The battery cell has terminals for current to flow into and out of the battery cell. The temperature sensor is configured to measure the cell temperature of the battery cell at a location remote from the terminals. The processor is configured to predict the terminal temperature based on the cell temperature and control the power supplied from the battery cell to a load based on the terminal temperature.

[0008] In addition to one or more features described herein, the battery cell is included in the battery module, and the temperature sensor includes one of the following: a maximum temperature sensor for measuring the highest temperature of the battery module or battery pack, a minimum temperature sensor for measuring the lowest temperature of the battery module or battery pack, and an average temperature sensor for measuring the average temperature of the battery module or battery pack. The processor is also configured to predict the contact temperature based on the current and cell temperature of the battery cell using a dynamic thermodynamic model of the battery cell. In one embodiment, the contact is in thermal contact with a busbar, and the busbar is in thermal contact with a heat sink, and the processor is further configured to use a dynamic thermodynamic model to determine the state of the battery cell, which includes heating of the contact, busbar, and heat sink due to current flowing through the contact. The processor is also configured to apply a Kalman filter to the state of the battery cell determined using the dynamic thermodynamic model to determine the contact temperature. The processor is also configured to reduce the power supplied to the load when the contact temperature is greater than or equal to a temperature limit.

[0009] The above-described features and advantages, as well as other features and advantages, of this disclosure will become apparent from the following detailed description when taken in conjunction with the accompanying drawings. Attached Figure Description

[0010] Other features, advantages, and details appear only by way of example in the following detailed description, which refers to the accompanying drawings, wherein:

[0011] Figure 1 A vehicle that can be operated using a battery pack as disclosed herein is shown;

[0012] Figure 2 It shows Figure 1 A detailed schematic diagram of the electrical system of a vehicle that can be operated using a battery pack;

[0013] Figure 3 A top view of the battery module in the battery pack is shown;

[0014] Figure 4 It shows along Figure 3 A side view of the connector portion of the battery module, taken from line 4-4;

[0015] Figure 5 A top view of a battery module according to another embodiment is shown;

[0016] Figure 6 It shows along Figure 5 The line 6-6 was cut Figure 5 A side view of the connector portion of the battery module;

[0017] Figure 7The graph shows the change in terminal temperature of the battery pack powering the electric motor of a vehicle operating at 80 miles per hour over time.

[0018] Figure 8 A graph showing the change in terminal temperature of the battery pack that powers the electric motor that operates the vehicle during high-power driving operations over time is shown.

[0019] Figure 9 A block diagram is shown of a method for estimating patch temperature using a Kalman filter in one embodiment;

[0020] Figure 10 A block diagram of a method for estimating patch temperature using a Kalman filter in another embodiment is shown;

[0021] Figure 11 It shows Figure 10 The output of the Kalman filter is compared with the simulated response of the actual temperature measurement;

[0022] Figure 12 A power margin diagram of the battery pack is shown;

[0023] Figure 13 A flowchart illustrating a method for managing the power output of a battery pack based on the temperature of the battery terminals is shown.

[0024] Figure 14 A schematic diagram of a method for predicting cell temperature using a neural network is shown. Detailed Implementation

[0025] The following description is exemplary in nature only and is not intended to limit this disclosure, its application, or use. It should be understood that in all the drawings, corresponding reference numerals denote the same or corresponding parts and features.

[0026] According to an exemplary embodiment, Figure 1 A vehicle 100 is shown that can be operated using the battery pack 102 disclosed herein. The vehicle 100 includes the battery pack 102 and an electrical load 104, which operates relying on power supplied by the battery pack 102. The vehicle 100 also includes a control system 106 for controlling the operation of the battery pack 102. The control system 106 includes a processor 108 and a storage device 110 storing various programs 112 or instructions. The processor 108 accesses the programs or instructions from the storage device 110 and executes the programs or instructions to perform the various operations disclosed herein. The processor 108 determines or calculates the temperature of the battery pack 102 or its components and controls the operation of the battery pack to maintain the temperature below a selected temperature threshold.

[0027] Figure 2 It shows Figure 1Detailed diagram 200 of the electrical system of vehicle 100. The electrical system includes battery pack 102 and electrical load 104. Electrical load 104 may include electric motor 202 of vehicle 100 and / or other electrical components 204, such as instrument lights, exterior lights, entertainment system, etc.

[0028] The battery pack 102 includes multiple battery modules 206a-206n connected in series by multiple buses 208a-208n. A bus temperature sensor 210 is shown disposed on bus 208a for measuring the temperature of bus 208a during operation of the battery pack 102. Although only one bus temperature sensor (i.e., bus temperature sensor 210) is shown, in various embodiments, other bus temperature sensors may be arranged on any of the multiple buses 208a-208n.

[0029] A battery circuit breaker 214 is disposed on the wire between the battery pack 102 and the electrical load 104. The battery circuit breaker 214 allows the vehicle operator to connect and disconnect the battery pack 102 from the electrical load 104. A battery disconnect unit 212 (also referred to herein as a "BDU") is disposed on another wire between the battery pack 102 and the electrical load 104. The battery disconnect unit 212 controls the flow of power from the battery pack 102 to the load based on a measured temperature at the battery pack 102, such as the contact temperature of the battery pack's cells. The battery disconnect unit 212 includes a temperature measurement function (T0) at the battery disconnect unit 212. BDU ) BDU sensor 216.

[0030] Figure 3 An embodiment is shown. Figure 2 A top view 300 of a battery module (e.g., battery module 206a). Battery module 206a includes a battery cell 302 and a connector 304 disposed at a connector 305. Figure 4 The cross-section 4-4 of the connector is shown in detail. The coolant line 306 allows coolant to flow along the axis of the battery module 206a to cool the battery module. In various aspects, the coolant generates areas of cooler temperature and areas of hotter temperature. A first temperature sensor 308 is located near the coolant line and measures the lowest or approximately lowest temperature (T0) of the battery module 206a. min The second temperature sensor 310 is located away from the coolant lines (near the outer edge of the battery cell) and measures the highest or approximately highest temperature of the battery cell (T). max ).

[0031] In various embodiments, the contact 304 is a component of the battery module 206a, which heats up the fastest due to current flow and is most susceptible to failure or burnout due to the high temperatures caused by current flow. Furthermore, the high temperatures generated at the contact point heat the battery cells and cause them to age rapidly. The method disclosed herein is based on temperature measurements obtained at different locations (i.e., T...). max T min The temperature of the terminal 304 is predicted using measurements of temperature and current, etc. In various embodiments, the terminal temperature is determined by solving a dynamic or thermodynamic model using temperature and current measurements. The predicted terminal temperature can then be used to calculate the power output of the battery cell or battery pack that allows the vehicle to operate safely.

[0032] Figure 4 The section cut along section line 4-4 is shown. Figure 3 A side view 400 of the connector 305 of the battery module 206a is shown. Side view 400 shows one end of the battery cell 302, the connector 304, the busbar 402, and the heat sink 408. The busbar 402 includes an electrical busbar 404 and a thermal busbar 406. The connector 304 extends between the battery cell 302 and the thermal busbar 406. Current from the battery cell 302 flows through the connector 304 and into the electrical busbar 404.

[0033] Heat can flow between the contact plate 304 and the battery cell 302, and between the contact plate 304 and the heat busbar 406. The heat busbar 406 is in thermal contact with the contact plate cooling material or the heat sink 408. The heat exchange between the battery cell 302, the contact plate 304, the heat busbar 406, and the heat sink 408 is given by a thermodynamic model. The thermodynamic model is given by the dynamic thermodynamic equations shown in equations (1)-(3):

[0034] C tab dT tab / dt=I 2 R tab -K1(T tab -T max )-K3(T bus -T tab Equation (1)

[0035] C bus dT bus / dt=I 2 R bus +K3(T bus -T tab )+K2(T sink -T bus Equation (2)

[0036] C sink dT sink / dt=K2(T sink -T bus )-K4(T sink -T cool Equation (3)

[0037] Among them, C tab It is the heat capacity of the 304 chip, C bus It is the heat capacity of the heat manifold 406, C sink I is the heat capacity of the heat sink 408, I is the current flowing from the battery cell 302 through the contact 304 and the thermal busbar 406, and R is the current. tab It's a 304 chip resistor, R bus It is the resistor of the 404 busbar. T tab It is the temperature of the 304 stainless steel splice, T. max The temperature measured at the first temperature sensor 308, T min The temperature T is measured at the second temperature sensor 310. bus It is the busbar temperature, T sink This is the temperature of the radiator 408. (T) cool It is the temperature of the surrounding environment. In equation (3), T cool You can use T min Instead, equations (1)-(3) can be solved using temperature measurements to determine the contact temperature T. tab .

[0038] Figure 5 A top view 500 of a battery module 206a according to another embodiment is shown. The battery module 206a includes battery cells 502 and contact points 504. An average temperature sensor 506 measures the average temperature (T) of the battery module 206a. avg Section line 6-6 is shown along the axis of battery cell 502.

[0039] Figure 6 The section taken along section line 6-6 is shown. Figure 5 A side view of the contact patch of the battery module 206a. The contact patch 504 provides the flow of current I and is in thermal contact with the busbar 602, which is in thermal contact with the cooling plate of the heat sink 604. The heat exchange between the battery cell 502, the contact patch 504, the busbar 602 and the heat sink 604 is given by a thermodynamic model, which includes a set of dynamic thermodynamic equations shown in equations (4)-(6):

[0040] C tab dT tab / dt=I 2 R tab -K1(T tab -T avg )-K3(T bus-T tab Equation (4)

[0041] C bus dT bus / dt=I 2 R bus +K3(T bus -T tab )-K4(T bus -T sink Equation (5)

[0042] C sink dT sink / dt=K2(T sink -T bus )-K4(T sink -T cool Equation (6)

[0043] Among them, T avg This is the average temperature measured at the average temperature sensor 506. Similar to equation (3), T... cool You can use T min replace.

[0044] In various embodiments, when the heat sink 604 is so low as to be negligible, equations (4)-(6) can be simplified. In this case, the cooling of the fin 504 depends more on the temperature of the heat sink 604. The simplified set of equations is shown in equations (7) and (8):

[0045] C tab dT tab / dt=I 2 R tab -K1(T tab -T avg )-K3(T bus -T tab Equation (7)

[0046] C bus dT bus / dt=I 2 R bus +K3(T bus -T tab )-K4(T bus -T cool Equation (8)

[0047] Figure 7 The T-shaped battery pack is shown. tabGraph 700 shows the value as a function of time for the battery pack, which powers the electric motor 202 of the vehicle traveling at 80 mph. The x-axis represents time (t), and the y-axis represents temperature (T). Curve 702 shows the actual junction temperature, while curve 704 shows the junction temperature calculated using equations (4)-(6). Curve 704 is consistent with curve 702 with 95% accuracy. Temperature threshold 706 shows the highest operating temperature of the battery cell junctions.

[0048] Figure 8 The T-shaped battery pack is shown. tab Graph 800 shows the value as a function of time for the battery pack supplying power to the electric motor 202 of the operating vehicle 100 under high-power driving control. Time (t) is displayed in seconds along the x-axis, and temperature (T) along the y-axis. Curve 802 shows the actual junction temperature, while curve 804 shows the junction temperature calculated using equations (4)-(6). Curve 804 matches curve 802 with 83% accuracy. Temperature threshold 806 shows the highest operating temperature of the battery cell junctions.

[0049] Figure 9 This example illustrates the use of a Kalman filter to estimate the patch temperature T in one embodiment. tab The method is illustrated in block diagram 900. The predicted temperature provided by the dynamic thermodynamic equations disclosed herein can be improved by using a Kalman filter. Block diagram 900 shows a dynamic model estimator 902 and a Kalman filter 904. The dynamic model estimator 902 receives input variables 906, including current (I), maximum temperature (T). max ) and minimum temperature (T min The thermodynamic state of the battery cell is calculated using equations based on the state variable T. tab T min and T max The linear combination of the observed parameters y determines the observed parameters y, as shown in equation (9):

[0050] y = a1T tab +a2 T min +a3T max Equation (9)

[0051] Input variables I, T max and T min It is also sent to the Kalman filter 904. The Kalman filter 904 receives the state variable, the observed parameter y, and the temperature (T) based on the battery disconnection unit 212. BDU The filtered temperature value is 908, as shown in equation (10):

[0052] y = T bdu / (τ(Tmax Equation (10) is given by equation (s+1).

[0053] Where τ is T max The function, and (τs+1) -1 The temperature T applied to the battery disconnection unit 212 bdu The Kalman filter 904 output junction temperature T tab The predicted value is 910.

[0054] Figure 10 A block diagram 1000 illustrates a method for estimating patch temperature using a Kalman filter in another embodiment. Block diagram 1000 shows a dynamic model estimator 1002 and a Kalman filter 1004. The dynamic model estimator 1002 receives current (I) and minimum temperature (T). min The input variable is 1006, and the thermodynamic state of the battery cell is calculated using equations (11)-(13).

[0055] c tab dT tab / dt=I 2 R tab -K1(T tab -T max )-K2(T sink -T tab Equation (11)

[0056] C bus dT bus / dt=I 2 R bus +K2(T sink -T tab )-K3(T sink -T min Equation (12)

[0057] C max dT max / dt=I 2 R max +K1(T tab -T max )-K4(T max -T min Equation (13)

[0058] The observed parameter y consists of these two values: T tab and T max As shown in equation (14):

[0059] y = [y1, y2] = [T] tab T max Equation (14)

[0060] Input variables 1006 (I and T) min And the maximum temperature T of the battery module max The measured parameter 1008 is also sent to the Kalman filter 1004. The Kalman filter 1004 outputs the contact temperature T. tab The predicted value is 1010.

[0061] Figure 11 It shows Figure 10 The output (Y1, Y2) of the Kalman filter is compared with the simulated response of the actual temperature measurement. Figure 1100 shows T tab The predicted value (curve 1104) and T tab A comparison of the measured values ​​(curve 1102). Curve 1102 agrees with curve 1104 with 93.88% accuracy. Graph 1110 shows T... max The predicted value (curve 1114) and T max Comparison of measured values ​​(curve 1112). Curve 1112 agrees with curve 1114 with 94.68% accuracy.

[0062] Figure 12 A power margin diagram 1200 for the battery pack is shown. The x-axis represents temperature, and the y-axis represents battery power. Therefore, based on the power margin diagram 1200, the battery pack power can be controlled or selected by predicting or calculating the contact temperature using the methods disclosed herein. Temperature limits divide the diagram into several operating regions. Temperature T1 marks the full-power operating region 1202 for the contacts. Temperatures T1 and T2 mark the power reduction region 1204. Temperatures T2 and T3 mark the minimum power operating region 1206. In the full-power operating region 1202, the battery pack can operate at full power (100% power) without causing thermal damage or thermal injury to the contacts or battery cells. No power regulation steps are required. In the power reduction region 1204, the power of the battery cells is reduced or decreased to prevent the power passing through the contacts from exceeding the power limit of the battery cells. The power reduction lowers the temperature of the battery contacts back below their temperature limit T1. The power reduction process in the power reduction region 1204 can be linearly related to temperature, as shown by the descent line 1208, or non-linearly related to temperature, as shown by the descent curve 1210. The reduction process can continue until the contact temperature reaches T2. Line 1212 represents the minimum allowable power at the load (e.g., the minimum propulsion power of motor 202) for temperatures above T2. Reducing the power below this line will shut down the vehicle. Therefore, power reduction ceases in the minimum power operating region 1206.

[0063] Figure 13A flowchart 1300 illustrates a method for managing the power output of a battery pack based on contact temperature. The method begins at block 1302. In block 1304, a check is performed to see if the contactor is closed for the high-voltage mainline or DC fast-charging line. If the contactor is not closed, the method loops back to block 1304 until it is closed. If the contactor is closed, the method proceeds to block 1306. In block 1306, the contact temperature T is predicted using the dynamic model disclosed herein or alternative modeling methods, such as using a neural network model or other nonlinear function model and lookup tables. tab .

[0064] In box 1308, a limiting contact temperature is defined. In box 1310, the predicted contact temperature is compared with the limiting contact temperature. If the predicted contact temperature is lower than the limiting contact temperature, the method loops back to box 1310. If the predicted contact temperature is greater than or equal to the limiting contact temperature, the method proceeds to box 1312. In box 1312, the maximum current limit of the battery cell is calculated based on the limiting contact temperature and the dynamic model. In box 1314, the allowable battery power is predicted based on the calculated maximum allowable current limit of the battery cell. This process can loop back from box 1314 to box 1306 to repeat. Otherwise, the process ends in box 1316.

[0065] Figure 14 A schematic diagram 1400 illustrates a method for predicting cell temperature using a neural network. In various embodiments, the neural network 1402 may be a recurrent neural network. The neural network contains multiple interconnected nodes. Each node performs an algorithm similar to multiple linear regression. The recurrent neural network includes recurrent layers. Each recurrent layer includes loop functions, so its input includes both the data to be analyzed and the output of calculations previously performed by that layer. Connections between nodes form a directional graph in time sequence. The neural network 1402 may receive multiple measurements u(t) as input 1404, such as battery current, minimum temperature, maximum temperature, and BDU temperature. The neural network 1402 generates the patch temperature T. tab The output is 1406. In subsequent time steps of the neural network, the patch temperature T can be... tab Reintroduced as input to neural network 1402 to improve the accuracy of the neural network.

[0066] Battery packs used in electric vehicles include battery modules and battery cells, with each battery cell having contacts for current flow. As current flows through the contacts, heat is generated, and excessively high contact temperatures can cause thermal damage to the battery. Due to the size and location of the contacts, directly placing temperature sensors on them for monitoring purposes is generally impractical. Therefore, this invention calculates the contact temperature of the battery cells or battery modules in the battery pack by using temperatures obtained at non-contact locations within the battery module, rather than directly measuring the contact temperature. The calculated contact temperature can be used to control the power usage of the battery pack. Controlling power usage to operate the battery cells within a safe temperature range prevents overheating of the battery cells and the battery pack, thereby extending the battery pack's lifespan.

[0067] While the foregoing disclosure has been described with reference to exemplary embodiments, those skilled in the art will understand that various changes and equivalent substitutions may be made without departing from its scope. Furthermore, many modifications may be made to adapt particular situations or materials to the teachings of this disclosure without departing from its essential scope. Therefore, it is intended that this disclosure be limited to the specific embodiments disclosed, but will include all embodiments falling within its scope.

Claims

1. A method for controlling the temperature of a battery cell, comprising: The cell temperature at the battery cell is measured. The battery cell includes contacts for current to flow into and out of the battery cell, wherein the cell temperature is obtained at a location away from the contacts. Predict the bonding temperature of the bonding pads based on the unit temperature; Power supplied from the battery cell to the load is controlled based on the temperature of the junction plate; Based on the current and cell temperature at the battery cell, a dynamic thermodynamic model of the heat exchange process around the cell terminals and busbars is used to predict the terminal temperature; and A Kalman filter is applied to the state of the battery cell determined using a dynamic thermodynamic model to determine the junction temperature.

2. The method according to claim 1, wherein, The battery cell is included in a battery module, and obtaining the cell temperature also includes obtaining one of the following: (i) The highest and lowest temperatures of the battery cells at the location where the battery module is separated from the battery cells; and (ii) Average temperature of the battery cell.

3. The method according to claim 1, wherein, The contact plate is in thermal contact with the busbar, and the busbar is in thermal contact with the heat sink. The dynamic thermodynamic model determines the state of the battery cell based on the heating of the contact plate, the busbar, and the heat sink caused by the current passing through the contact plate.

4. The method according to claim 1 further includes reducing the power supplied to the load when the temperature of the contact plate is greater than or equal to the temperature limit.

5. A system for controlling the temperature of a battery cell, comprising: A temperature sensor is configured to measure the cell temperature at a battery cell, the battery cell including tabs for current inflow and outflow from the battery cell, wherein the temperature sensor is located away from the tabs; and The processor is configured as follows: Predict the bonding temperature of the bonding pads based on the unit temperature; The power supplied from the battery cell to the load is controlled based on the contact temperature. Based on the current and cell temperature at the battery cell, a dynamic thermodynamic model of the heat exchange process around the cell contacts and busbars is used to predict the contact temperature. and A Kalman filter is applied to the state of the battery cell determined using a dynamic thermodynamic model to determine the junction temperature.

6. The system according to claim 5, wherein, The battery cell is included in the battery module, and the temperature sensor further includes one of the following: (i) a maximum temperature sensor for measuring the highest temperature of the battery module and a minimum temperature sensor for measuring the lowest temperature of the battery module; and (ii) An average temperature sensor for measuring the average temperature of the battery cells.

7. The system according to claim 5, wherein, The contact patch is in thermal contact with the busbar, and the busbar is in thermal contact with the heat sink. The processor is also configured to determine the state of the battery cell using a dynamic thermodynamic model based on the heating of the contact patch, the busbar, and the heat sink due to the current passing through the contact patch.

8. The system according to claim 5, wherein, The processor is also configured to reduce the power supplied to the load when the patch temperature is greater than or equal to the temperature limit.

Images