A battery charging abnormality intelligent early warning system and early warning method

Abstract

This invention belongs to the field of battery charging technology, and relates to an intelligent early warning system and method for battery charging anomalies. The early warning method first acquires the first real-time voltage V at point P1. in and the second real-time voltage V at point P2 out Then, based on the first real-time voltage V in Second real-time voltage V out Calculate the real-time charging current *i*, and then calculate the derivative of *i* with respect to time. Finally, determine whether charging is complete based on the rate of change of the value of *i*: if charging is complete, use the average current over the current time period as *I*. Mi The current is stored in the MCU chip as the initial value for the next charge, and the MCU chip controls the alarm device to sound an alarm when charging is complete. The early warning system provided by this invention can monitor the charging time and charging current in real time, and determine the charging status based on the above values. It can automatically cut off the charging circuit and end the charging process when the temperature is too high.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of battery charging, and relates to a battery charging abnormality intelligent early warning system and method. BACKGROUND

[0002] With the continuous progress of science and technology, electric vehicles and mobile phones and other electronic products using rechargeable batteries have been widely used. However, there are reports of fire caused by charging of rechargeable batteries, and the loss is heavy.

[0003] At present, most chargers lack charging abnormality detection and control parts, and the charger only has a charging function without detection and power-off function, so how the charger overcomes the above-mentioned shortcomings and alarms when a fire has not yet occurred in the early stage of charging abnormality is an urgent need for the current charger.

[0004] Therefore, the present application is proposed. SUMMARY

[0005] The present application aims to overcome the shortcomings of the prior art, and provides a battery charging abnormality intelligent early warning system and method, which has the advantages of low cost, strong function, etc., and can be widely applied to chargers of electric vehicles, mobile phones and other electronic products.

[0006] To achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0007] On the one hand, the present application provides a battery charging abnormality intelligent early warning system, which comprises an MCU chip and a charging circuit, the charging circuit comprising a triode T1,

[0008] The emitter of the triode T1 is connected with one end of a first capacitor C1 and grounded, and the other end of the first capacitor C1 is connected with a device to be charged. The base of the triode T1 is connected with the MCU chip through a first resistor R1, and the collector of the triode T1 is connected with an input power supply through a fifth resistor R5 and a MOS power transistor M1. The gate of the MOS power transistor M1 is connected with the fifth resistor R5, the source is connected with the input power supply, and the drain is connected with the device to be charged. The source of the MOS power transistor M1 is also connected with the collector of the triode T1 through a second resistor R2.

[0009] The first real-time voltage V in of the P1 point in the charging circuit is input to the first input end of the MCU chip through a first sampling circuit, the second real-time voltage V out of the P2 point in the charging circuit is input to the second input end of the MCU chip through a second sampling circuit, and the third input end of the MCU chip also collects real-time temperature information T of the MOS power transistor M1 through a third sampling circuit. The output end of the MCU chip is connected with an alarm device.

[0010] Specifically, the first sampling circuit comprises a third resistor R3 and a first analog-to-digital conversion chip ADC1 connected in sequence between a P1 point and a first input end of the MCU chip, one end of the third resistor R3 being connected to the P1 point and the other end being grounded through a fourth resistor R4.

[0011] Specifically, the second sampling circuit comprises a sixth resistor R6 and a second analog-to-digital conversion chip ADC2 connected in sequence between a P2 point and a second input end of the MCU chip, one end of the sixth resistor R6 being connected to the P2 point and the other end being grounded through a seventh resistor R7.

[0012] Specifically, the third sampling circuit comprises a temperature sensor S1 and a third analog-to-digital conversion chip ADC3 connected in series, the temperature sensor S1 being used to monitor real-time temperature information T of the MOS power transistor M1.

[0013] Specifically, the alarm device comprises a sound alarm and a light alarm. Alarm sound is stored in a storage unit of the MCU chip in advance, and is directly called and sent to the alarm device when alarming. The alarm device comprises a digital-to-analog conversion chip MS4344, which converts the digital sound transmitted by the MCU chip into analog sound, and then the sound is played through an operational amplifier LM358 and a loudspeaker. The light alarm of the alarm device is completed by a red light LED, and the alarm is directly controlled by the MCU chip.

[0014] Further, the temperature sensor S1 is located within a circular region with the position of the MOS power transistor M1 as the center and 1 cm as the radius. For example, the temperature sensor S1 is within 5 mm from the connection between the heat sink at the bottom of the MOS power transistor and the copper sheet.

[0015] Before the whole early warning system is used, the storage unit of the MCU chip stores a relationship curve between the on-resistance R of the MOS power transistor M1 and the real-time temperature information T, and the MCU chip can retrieve the corresponding on-resistance R according to the real-time temperature information T, so as to effectively overcome the calculation error caused by the change of the on-resistance R with temperature. Then, the real-time current i is calculated according to the formula i = (V out -V in ) / R, so as to ensure the accuracy of the calculation result.

[0016] It is to be further explained that, in the early warning system, the sampling frequency of the first analog-to-digital conversion chip ADC1 and the second analog-to-digital conversion chip ADC2 is not less than 100 MHz, and the third resistor R3, the fourth resistor R4, the sixth resistor R6 and the seventh resistor R7 all adopt high-precision resistors (error value < 10%), which is beneficial to obtaining more accurate first real-time voltage V in and second real-time voltage V outIn addition, the output of the first analog-to-digital conversion chip ADC1, the second analog-to-digital conversion chip ADC2 and the third analog-to-digital conversion chip ADC3 is a 16-bit digital signal, which can provide higher precision and realize accurate measurement.

[0017] In another aspect, the application further provides a warning method of the battery charging abnormal intelligent warning system, under the premise that the charging circuit is turned on, the first real-time voltage V in at the P1 point and the second real-time voltage V out at the P2 point are obtained respectively. in out Then, the real-time charging current i is calculated based on the first real-time voltage V in and the second real-time voltage V out , and the derivative of i with respect to time is calculated. Finally, whether the charging is completed is determined according to the rate of change of the value of : if the charging is completed, the average value of the current in the current time period is taken as I Mi , and is stored to the MCU chip as the initial value of the current for the next charging, and the MCU chip controls the alarm device to perform charging completion alarm.

[0018] During the whole charging process, when the temperature information T of the MOS power transistor M1 received by the MCU chip is greater than the preset threshold T h , it is determined that the charging is abnormal, the MCU chip disconnects the MOS power transistor M1, stops charging and starts the alarm device to perform charging abnormality alarm; wherein is defined as the average value of all temperature information T in the past 5 days. The charging abnormality alarm sound is "charging abnormality", and the red light-emitting diode in the alarm device flashes once every 0.2s, prompting the user to disconnect the power supply.

[0019] In the initial charging stage, if the real-time charging current i is greater than or equal to 0.1I Mi , it indicates that the useful electrical equipment is connected, and the MOS power transistor M1 remains turned on; otherwise, the MCU chip disconnects the MOS power transistor M1 through the triode T1 to stop charging.

[0020] Further, the warning method specifically includes the following steps:

[0021] Step 1, under the premise that the charging circuit is turned on, the MCU chip turns on the MOS power transistor M1 through the triode T1 to connect the input power supply, and the first real-time voltage V in at the P1 point and the second real-time voltage V out at the P2 point are obtained respectively.

[0022] Step 2, the first real-time voltage V in and the second real-time voltage V outCalculating real-time charging current i;

[0023] Step 3, calculating the derivative of real-time charging current i with respect to time

[0024] Step 4, judging whether the charging is completed according to the rate of change of the value of

[0025] Step 4.1, if the rate of change of the value of is less than 3% and lasts for 30min~40min, it is judged that the charging has been completed, the average value of the current in the 30min~40min is calculated, and the average value of the current is taken as I Mi and stored as the initial value of the current at the next charging; wherein, the rate of change of the value of is equal to the absolute value of the derivative of t;

[0026] Step 4.2, the MCU chip controls the alarm device to broadcast the sound of "charging is completed, please disconnect the power supply", and the red light emitting diode in the alarm device flashes once every specified time t1, prompting the user to disconnect the power supply; if the MCU chip receives the first real-time voltage V in of P1 point is zero, it is judged that the input power has been disconnected by the user, otherwise, the MCU automatically controls the MOS power transistor M1 to be disconnected after continuing to charge for 1min~10min, and the charging is stopped.

[0027] Compared with the prior art, the technical scheme provided by the present application has the following beneficial effects:

[0028] 1) When the MCU chip controls the MOS power transistor to be turned on, if the calculated real-time current value i≥0.1I Mi , it indicates that the useful electrical equipment is connected, the MOS power transistor remains turned on, otherwise, the MCU chip controls the MOS power transistor M1 to be disconnected, and the charging is stopped. Moreover, the storage unit of the MCU chip stores the curve relationship between the on-resistance R of the MOS power transistor M1 and the real-time temperature information T, the real-time temperature information T of the MOS power transistor M1 is monitored in real time by the temperature sensor S1 arranged near the MOS power transistor, the real-time temperature information T is input into the MCU chip through the third analog-digital conversion chip ADC3, the MCU chip retrieves the corresponding on-resistance R of the MOS power transistor M1 according to the real-time temperature information T, and this method can effectively overcome the calculation error caused by the change of the on-resistance R with temperature.

[0029] ​2) The early warning system provided by the application, the first analog-digital conversion chip, the second analog-digital conversion chip and the third analog-digital conversion chip all output 16-bit digital signals, and the sampling frequency of the first analog-digital conversion chip and the second analog-digital conversion chip is not less than 100MHz. The first analog-digital conversion chip inputs the first real-time voltage of P1 point, and the second analog-digital conversion chip inputs the second real-time voltage of P2 point, the first real-time voltage is the input voltage, and the second real-time voltage is the output voltage. The MCU chip controls the on-off of the MOS power transistor through the bipolar NPN triode.

[0030] 3) The early warning system provided by the application, the alarm device is used to provide sound and light alarm, the alarm sound is stored in the MCU chip in advance, and the alarm sound is directly called and sent to the alarm device during alarm, the sound alarm of the alarm device comprises a digital-analog conversion chip MS4344, the digital sound transmitted by the MCU chip is converted into analog sound, and the sound is played through the operational amplifier LM358 and the loudspeaker. The light alarm of the alarm device is completed by a red light LED, and the alarm is realized by directly controlling the MCU chip.

[0031] 4) The early warning system provided by the application can monitor the charging time length and the charging current size in real time, and judge the charging state according to the above-mentioned values in real time, so that the charging circuit can be automatically cut off and the charging process can be ended when the temperature is too high. BRIEF DESCRIPTION OF DRAWINGS

[0032] The accompanying drawings, which are incorporated into and form part of the specification, are included to explain the principles of the application and, to this end, will be briefly described.

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the accompanying drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, those skilled in the art can obtain other drawings according to these drawings without any creative effort.

[0034] Figure 1 The principle block diagram of the battery charging abnormal intelligent early warning system provided by the application;

[0035] Figure 2 The flowchart of the battery charging abnormal intelligent early warning method provided by the application.

[0036] Wherein: T1, triode; C1, first capacitor; R, on-resistance of MOS power transistor; R1, first resistor; R2, second resistor; R3, third resistor; R4, fourth resistor; R5, fifth resistor; R6, sixth resistor; R7, seventh resistor; M1, MOS power transistor; V in , first real-time voltage of P1 point; V out, the second real-time voltage of P2 point; S1, temperature sensor; T, real-time temperature information of MOS power transistor; ADC1, first analog-digital conversion chip; ADC2, second analog-digital conversion chip; ADC3, third analog-digital conversion chip. DETAILED DESCRIPTION

[0037] The exemplary embodiments will be described in detail below with reference to the drawings. The embodiments described in the following exemplary embodiments do not represent all the embodiments consistent with the present application. Rather, they are merely examples consistent with some aspects of the present application as detailed in the appended claims.

[0038] In order for those skilled in the art to better understand the technical solutions of the present application, the present application will be described in further detail below with reference to the drawings and embodiments.

[0039] EMBODIMENT

[0040] The present embodiment provides a battery charging abnormality intelligent early warning system, the principle diagram of which is shown in Figure 1 The charging circuit comprises a triode T1, a first capacitor C1, a fifth resistor R5 and a MOS power transistor M1.

[0041] The emitter of the triode T1 is connected with one end of the first capacitor C1 and grounded, and the other end of the first capacitor C1 is connected with the device to be charged. The base of the triode T1 is connected with the MCU chip through the first resistor R1, and the collector of the triode T1 is connected with the input power supply through the fifth resistor R5 and the MOS power transistor M1. The gate of the MOS power transistor M1 is connected with the fifth resistor R5, the source is connected with the input power supply, and the drain is connected with the device to be charged. The source of the MOS power transistor M1 is also connected with the collector of the triode T1 through the second resistor R2.

[0042] The first real-time voltage V in of P1 point in the charging circuit is input to the first input end of the MCU chip through the first sampling circuit, and the second real-time voltage V out of P2 point in the charging circuit is input to the second input end of the MCU chip through the second sampling circuit. The third input end of the MCU chip also collects the real-time temperature information T of the MOS power transistor M1 through the third sampling circuit. The output end of the MCU chip is connected with the alarm device.

[0043] Further, the first sampling circuit comprises a third resistor R3 and a first analog-digital conversion chip ADC1 connected in sequence between P1 point and the first input end of the MCU chip. One end of the third resistor R3 is connected with P1 point, and the other end is grounded through a fourth resistor R4.

[0044] Further, the second sampling circuit comprises a sixth resistor R6 and a second analog-digital conversion chip ADC2 connected in sequence between the P2 point and the second input end of the MCU chip, one end of the sixth resistor R6 is connected with the P2 point, and the other end is grounded through a seventh resistor R7.

[0045] Further, the third sampling circuit comprises a temperature sensor S1 and a third analog-digital conversion chip ADC3 connected in series, and the temperature sensor S1 is used to monitor the real-time temperature information T of the MOS power transistor M1.

[0046] Preferably, the alarm device comprises a sound alarm and a light alarm. The sound alarm comprises a digital-analog conversion chip MS4344, which can convert the digital sound transmitted by the MCU chip into analog sound, and then the sound is played through the operational amplifier LM358 and the speaker. The light alarm of the alarm device is completed by a red light LED, which is directly controlled by the MCU chip to realize the alarm.

[0047] In the early warning system, the temperature sensor S1 is located near the MOS power transistor, specifically, in a circular region with the MOS power transistor M1 as the center and 1cm as the radius; for example, the temperature sensor S1 is within 5mm from the connection between the heat sink at the bottom of the MOS power transistor and the copper sheet.

[0048] Before the whole early warning system is used, the storage unit of the MCU chip stores the relationship curve between the on-resistance R of the MOS power transistor M1 and the real-time temperature information T, the MCU chip can retrieve the corresponding on-resistance R according to the real-time temperature information T, which can effectively overcome the calculation error caused by the change of the on-resistance R with temperature, and then calculate the real-time current i according to the formula i=(V out -V in ) / R, to ensure the accuracy of the calculation result.

[0049] It is to be further explained that in the early warning system, the sampling frequency of the first analog-digital conversion chip ADC1 and the second analog-digital conversion chip ADC2 is not less than 100MHz, and the third resistor R3, the fourth resistor R4, the sixth resistor R6 and the seventh resistor R7 all adopt high-precision resistors (error value <10%), which is conducive to obtaining more accurate first real-time voltage and second real-time voltage. In addition, the outputs of the first analog-digital conversion chip ADC1, the second analog-digital conversion chip ADC2 and the third analog-digital conversion chip ADC3 are all 16-bit digital signals, which can provide higher precision and realize accurate measurement.

[0050] In addition, the embodiment also provides an early warning method of the battery charging abnormal intelligent early warning system, which comprises the steps of acquiring the first real-time voltage V inthe second real-time voltage V out ; then the first real-time voltage V in and the second real-time voltage V out is calculated, and the derivative of i with respect to time is calculated Finally, according to the rate of change of the value of , it is determined whether the charging is completed: if the charging is completed, the average value of the current in the current time period is taken as I Mi , and is stored in the MCU chip as the initial value of the current for the next charging, and the MCU chip controls the alarm device to perform charging completion alarm.

[0051] It should be noted that, during the entire charging process, when the temperature information T of the MOS power transistor M1 received by the MCU chip is greater than the preset threshold T h , it is determined that the charging is abnormal, the MCU chip disconnects the MOS power transistor M1, stops charging and starts the alarm device to perform charging abnormality alarm; wherein, the threshold T is defined as the average value of all temperature information T in the past 5 days. The charging abnormality alarm sound is "charging abnormality", and the red light-emitting diode in the alarm device flashes once every 0.2s, prompting the user to disconnect the power supply.

[0052] Referring to Figure 2 , the early warning method specifically includes the following steps:

[0053] Step 1, set I Mi initial value as 0.003A, if the real-time charging current i≥0.1I Mi , it indicates that the useful electrical equipment is connected, the MCU chip makes the MOS power transistor M1 conductive to connect the input power supply through the triode T1, and the first real-time voltage V in at P1 point and the second real-time voltage V out at P2 point are obtained respectively.

[0054] Step 2, based on the first real-time voltage V in and the second real-time voltage V out , the real-time charging current i is calculated; set the on-resistance of the MOS power transistor M1 as R, then the real-time charging current is i=(V out -V in ) / R.

[0055] If i≥I Mi / 10, indicating that the useful electric facility accesses the charging end, the MOS power transistor M1 keeps on, otherwise, the MCU chip makes the MOS power transistor M1 off through the transistor T1; the on-resistance R of the MOS power transistor M1 and the temperature relation curve are stored in the storage unit of the MCU chip before the MOS power transistor M1 is used normally. Figure 1 In the middle, S1 is a temperature sensor arranged near the MOS power transistor M1 for measuring the real-time temperature information T of M1, T is input to the MCU chip through the third analog-digital conversion chip ADC3, and the MCU chip retrieves the on-resistance R corresponding to the MOS power transistor M1 according to the real-time temperature information T, so as to effectively overcome the calculation error caused by the change of the on-resistance R with temperature;

[0056] Step 3, calculating the derivative of the real-time charging current i with respect to time

[0057] Step 4, judging whether the charging is completed according to the value change rate of

[0058] Step 4.1, if the value change rate of is less than 3% and lasts for 30 min, it is judged that the charging has been completed, the average value of the current in the 30 min is calculated, and the average value of the current is taken as I Mi and stored as the initial value of the current for the next charging; wherein, The value change rate of is equal to the absolute value of the derivative of

[0059] Step 4.2, the MCU chip controls the alarm device to broadcast the sound of "charging is completed, please disconnect the power supply", and the red light-emitting diode in the alarm device flashes every 1s, prompting the user to disconnect the power supply; if the MCU chip receives the first real-time voltage V in of P1 point is zero, it is judged that the input power has been disconnected by the user, otherwise, the MOS power transistor M1 is automatically controlled to be off by the MCU after the charging lasts for 5 min, and the charging is stopped.

[0060] It is additionally explained that if the value change rate of is less than 3%, in order to ensure that the equipment to be charged can be fully charged and safe, the charging can last for 30 min to 40 min; when it is judged that the input power is not disconnected by the user, the MOS power transistor M1 can be disconnected by the MCU chip after the charging lasts for 1 min to 10 min, and the charging is stopped.

[0061] ​The foregoing is considered as illustrative only of the principles of the application. Numerous modifications and changes will readily occur to those skilled in the art, and the generic principles defined herein can be applied to other embodiments without departing from the spirit or scope of the application.

[0062] It is to be understood that the application is not limited to the embodiments described above, and various modifications and changes can be made without departing from the scope of the present application. The scope of the application is limited only by the claims that follow.

Claims

1. A method for intelligent early warning of abnormal battery charging, characterized in that, The aforementioned early warning method is based on a battery charging anomaly intelligent early warning system. This system includes an MCU chip and a charging circuit, the latter comprising a transistor (T1). The emitter of the transistor (T1) is connected to one end of the first capacitor (C1) and grounded, while the other end of the first capacitor (C1) is connected to the device to be charged. The base of the transistor (T1) is connected to the MCU chip via the first resistor (R1), and the collector of the transistor (T1) is connected to the input power supply via the fifth resistor (R5) and the MOS power transistor (M1). The gate of the MOS power transistor (M1) is connected to the fifth resistor (R5), the source is connected to the input power supply, and the drain is connected to the device to be charged. A second resistor (R2) is also connected between the source of the MOS power transistor (M1) and the collector of the transistor (T1). The first real-time voltage (V) at point P1 in the charging circuit in The second real-time voltage (V) at point P2 in the charging circuit is input to the first input terminal of the MCU chip via the first sampling circuit. out The data is input to the second input terminal of the MCU chip via the second sampling circuit. The third input terminal of the MCU chip also collects the real-time temperature information (T) of the MOS power transistor (M1) through the third sampling circuit. The output terminal of the MCU chip is connected to an alarm device. The MCU chip stores the relationship curve between the on-resistance (R) of the MOS power transistor (M1) and the real-time temperature information (T) in its storage unit. The MCU chip can retrieve the corresponding on-resistance (R) based on the real-time temperature information (T). With the charging circuit on, first obtain the first real-time voltage (V) at point P1. in ) and the second real-time voltage (V) at point P2 out Then, based on the first real-time voltage (V) in ) and second real-time voltage (V out And the on-resistance (R) is calculated according to the formula i = (V out -V in ) / R calculates the real-time charging current i, and calculates the derivative of i with respect to time. Finally, according to The rate of change of the current value determines whether charging is complete: if charging is complete, the average current value within the current time period is taken as I. Mi The current is stored in the MCU chip and used as the initial value for the next charge. At the same time, the MCU chip controls the alarm device to sound an alarm when charging is complete. During the entire charging process, when the temperature information T of the MOS power transistor (M1) received by the MCU chip is greater than the preset threshold T... h If the condition is abnormal, the MCU chip will disconnect the MOS power transistor (M1), stop charging, and activate the alarm device to issue a charging abnormality alarm; where, the definition is... This is the average of all temperature information T over the past 5 days; In the initial stage of charging, if the real-time charging current i ≥ 0.1I Mi If the signal is positive, it indicates that an electrical device is connected, and the MOS power transistor (M1) remains on; otherwise, the MCU chip disconnects the MOS power transistor (M1) through the transistor (T1) and stops charging. if If the rate of change of the current value is less than 3% and lasts for 30 to 40 minutes, then charging is considered complete. Calculate the average current value within this 30 to 40 minutes and use this average current value as I. Mi And store it as the initial current value for the next charging; where, The rate of change of the value equals Take the absolute value after differentiating with respect to t; The MCU chip controls the alarm device to broadcast the message "Charging complete, please disconnect the power." At the same time, the red LED in the alarm device flashes once every specified time t1 to remind the user to disconnect the power. If the MCU chip receives the first real-time voltage (Vin) at point P1 as zero, it determines that the input power has been disconnected by the user. Otherwise, after charging for another 1 to 10 minutes, the MCU automatically controls the MOS power transistor (M1) to disconnect and stop charging.

2. The intelligent early warning method for abnormal battery charging according to claim 1, characterized in that, Specifically, the steps include the following: Step 1: With the charging circuit on, the MCU chip turns on the MOS power transistor (M1) through the transistor (T1) to connect the input power supply, and obtains the first real-time voltage (V) at point P1. in ) and the second real-time voltage (V) at point P2 out ); Step 2, based on the first real-time voltage (V) in ) and second real-time voltage (V out Calculate the real-time charging current i; Step 3: Calculate the derivative of the real-time charging current i with respect to time. Step 4, according to The rate of change of the value determines whether charging is complete.

3. The intelligent early warning method for abnormal battery charging according to claim 1, characterized in that, The first sampling circuit includes a third resistor (R3) and a first analog-to-digital converter chip (ADC1) connected in sequence between point P1 and the first input terminal of the MCU chip. One end of the third resistor (R3) is connected to point P1, and the other end is grounded through a fourth resistor (R4).

4. The intelligent early warning method for abnormal battery charging according to claim 1, characterized in that, The second sampling circuit includes a sixth resistor (R6) and a second analog-to-digital converter chip (ADC2) connected in sequence between point P2 and the second input terminal of the MCU chip. One end of the sixth resistor (R6) is connected to point P2, and the other end is grounded through a seventh resistor (R7).

5. The intelligent early warning method for abnormal battery charging according to claim 1, characterized in that, The third sampling circuit includes a temperature sensor (S1) and a third analog-to-digital converter chip (ADC3) connected in series. The temperature sensor (S1) is used to monitor the real-time temperature information (T) of the MOS power transistor (M1).

6. The intelligent early warning method for abnormal battery charging according to claim 5, characterized in that, The temperature sensor (S1) is located within a circular area with a radius of 1 cm centered on the location of the MOS power transistor (M1).

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