Detection circuit and operating method thereof

Abstract

The invention provides a detection circuit and an operation method thereof. The detection circuit comprises: a voltage source (V1); a ground (G1); the first end of the first resistor (R1) is connected to the voltage source (V1); the first end of the thermistor (RT1) is connected to the second end of the first resistor (R1); the first end of the second resistor (R2) is connected to a connection point between the thermistor (RT1) and the first resistor (R1); a first switching element (Q1), wherein the first switching element (Q1) is connected between the second end of the second resistor (R2) and the ground (G1); and the second switch element (Q2) is connected between the second end of the thermistor (RT1) and the ground (G1).

Description

Detection circuit and operation method thereof Technical Field

[0001] The present invention generally relates to a detection circuit and an operating method thereof, and particularly relates to a detection circuit and an operating method thereof for a power tool (eg, a motor of a power tool). Background Art

[0002] Typically, a power tool includes a motor and a circuit for controlling the motor. The circuit includes a power supply and a ground, and includes various power devices, the temperatures of which need to be monitored to ensure the normal operation of the circuit. Figure 2 shows a voltage source V1 and a ground G1, with resistors R1 and RT1 arranged in series between the voltage source V1 and the ground G1. Resistor RT1 is a thermistor and can be used as a temperature sensor. RT1 can be used to detect the temperature of the power device. When it is detected that the temperature of the power device exceeds a temperature threshold, the control unit needs to adjust the operation of the circuit and the motor. In addition, the circuit also includes a circuit pin P1 located between R1 and RT1, which can be detected to obtain the voltage value there, and then determine whether the circuit is in a suspended (or floating or suspended) state. The circuit also includes a detection point TP1, which is used as a test point for the circuit.

[0003] Since the resistance value of RT1 varies with temperature, the voltage divider of the power supply voltage detected at test point TP1 is not a constant value, and therefore the voltage of voltage source V1 cannot be calibrated based on this. Secondly, since the voltage divider value is not constant, the floating state of pin P1 cannot be determined, and the floating state of resistor RT1 cannot be determined either. In addition, the control unit determines the resistance value of RT1 and thus the temperature through the voltage divider at point TP1. However, the voltage divider value monitored by the control unit is usually within a limited range, that is, it can only monitor a smaller temperature range. When the temperature exceeds this temperature range, the voltage divider value at point TP1 will exceed the monitoring range of the control unit, resulting in an inability to accurately monitor the temperature of the power device.

[0004] Summary of the Invention

[0005] The present invention provides a detection circuit and an operating method thereof, which solves one or more of the above problems.

[0006] The present invention discloses a detection circuit, comprising: a voltage source (V1); a ground (G1); a first resistor (R1), wherein a first end of the first resistor (R1) is connected to the voltage source (V1); a thermistor (RT1), wherein a first end of the thermistor (RT1) is connected to a second end of the first resistor (R1); a second resistor (R2), wherein a first end of the second resistor (R2) is connected to a connection point between the thermistor (RT1) and the first resistor (R1); a first switching element (Q1), wherein the first switching element (Q1) is connected between the second end of the second resistor (R2) and the ground (G1); and a second switching element (Q2), wherein the second switching element (Q2) is connected between the second end of the thermistor (RT1) and the ground (G1).

[0007] According to one embodiment of the present invention, the first switching element (Q1) and the second switching element (Q2) are transistors.

[0008] According to one embodiment of the present invention, the thermistor (RT1) is a negative temperature coefficient thermistor.

[0009] According to one embodiment of the present invention, the detection circuit further includes a pin (P1) located between the first resistor (R1) and the thermistor (RT1).

[0010] According to one embodiment of the present invention, the detection circuit further comprises a first capacitor (C1) connected in parallel with the thermistor (RT1) between the first resistor (R1) and the ground (G1).

[0011] According to one embodiment of the present invention, the detection circuit further includes a drive circuit for controlling the first switching element (Q1), the drive circuit including: a third resistor (R3) and a second capacitor (C2), the third resistor (R3) and the second capacitor (C2) being sequentially connected between the control end of the first switching element (Q1) and the ground (G1); and a fourth resistor (R4), the fourth resistor (R4) being connected in parallel with the third resistor (R3) and the second capacitor (C2) between the control end of the first switching element (Q1) and the ground (G1).

[0012] According to one embodiment of the present invention, the detection circuit further includes a drive circuit for controlling the second switching element (Q2), the drive circuit including: a fifth resistor (R5), the fifth resistor (R5) being connected between the control end of the second switching element (Q2) and the controller of the detection circuit; and a sixth resistor (R6), the sixth resistor (R6) being connected between the control end of the second switching element (Q2) and the ground (G1).

[0013] The present invention discloses a method for operating the detection circuit as described above, the method comprising the step of turning off the first switching element (Q1) and the second switching element (Q2) to detect the voltage value at the connection point between the thermistor (RT1) and the first resistor (R1).

[0014] According to one embodiment of the present invention, the method further includes the steps of turning on the first switching element (Q1) and turning off the second switching element (Q2) to detect a voltage value at a connection point between the thermistor (RT1) and the first resistor (R1).

[0015] According to one embodiment of the present invention, the method further includes the step of turning on the first switching element (Q1) and the second switching element (Q2) to detect a voltage value at a connection point between the thermistor (RT1) and the first resistor (R1).

[0016] According to one embodiment of the present invention, the method further includes the step of turning off the first switching element (Q1) and turning on the second switching element (Q2) to detect a voltage value at a connection point between the thermistor (RT1) and the first resistor (R1).

[0017] According to one embodiment of the present invention, the method further includes the step of turning off the first switching element (Q1) and turning on the second switching element (Q2), when the voltage value at the connection point between the thermistor (RT1) and the first resistor (R1) exceeds a predetermined value, turning on the first switching element (Q1) to detect the voltage value at the connection point between the thermistor (RT1) and the first resistor (R1).

[0018] According to one embodiment of the present invention, the method further comprises: selectively executing one or more of the steps according to control logic.

[0019] The present invention discloses a control system, which is used to execute the method described above, wherein the control system selectively executes one or more of the steps according to control logic.

[0020] The detection circuit and operating method of the present invention can implement voltage calibration of a voltage source, can implement floating detection of circuit pins, can also implement floating detection and / or short circuit detection of a temperature-sensitive resistor in the circuit, and can also expand the temperature monitoring range of the temperature-sensitive resistor. The detection circuit of the present invention has a simple structure, is easy to operate, is low in cost, can implement multiple functions, has good versatility, and can be applied to various tools and / or motors, such as power tools and their motors. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] FIG. 1 is a perspective view of an exemplary power tool and components thereof as described herein.

[0022] FIG2 is a diagram of a prior art circuit.

[0023] FIG3 is a diagram of a first embodiment of the circuit of the present invention.

[0024] FIG4 is a diagram of a second embodiment of the circuit of the present invention.

[0025] FIG5 is a flow chart of the operation of the circuit of FIG4. DETAILED DESCRIPTION

[0026] The preferred embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. The following description is exemplary and not intended to limit the present invention. Any other similar situations also fall within the scope of protection of the present invention.

[0027] The present invention relates to a power tool 100. This document describes the concepts of the present invention using a circular saw as an example, but the present invention is not limited thereto. The power tool may also be other types of power tools known or commonly used in the art, such as jigsaws, track saws, jigsaws, and other saws, drills, hammer drills, impact drills, planes, screwdrivers, milling cutters, grinders, angle grinders, vibrating grinders, gardening tools, and / or multi-tools. Accordingly, the inventive concepts herein are equally applicable to these power tools. Furthermore, these power tools may have various structures and components, which will not be described in detail. The present invention will focus on the aspects of the inventive concepts below.

[0028] FIG1 is a perspective view of a power tool according to the present invention. The power tool 100 includes a motor 10 and a control circuit board (PCB) 20 for controlling the motor 10. While the diagram illustrates PCB 20 positioned in the left front portion of the motor 10, this is merely an example. PCB 20 may be positioned in any suitable location relative to the motor 10 and electrically coupled to the motor to control it. The motor 10 may be any type of motor, such as a brushless motor, a brushed motor, a DC motor, or an AC motor.

[0029] FIG2 illustrates the relevant circuitry within PCB 20. As previously mentioned, the figure shows that this portion includes a voltage source V1 and a ground G1 for powering the circuit. Resistors R1 and RT1 are arranged in series between voltage source V1 and ground G1, and resistor RT1 is also connected in parallel with capacitor C1 to form an RC circuit. Resistor RT1 is a thermistor or temperature-sensitive resistor, such as an NTC (negative temperature coefficient) thermistor. The resistance of an NTC thermistor decreases as temperature increases, so RT1 can be used as a temperature sensor. RT1 is located near a power device (e.g., a MOS transistor) in the circuit and is used to detect its temperature. When the temperature of the power device is detected to be too high (e.g., exceeding a temperature threshold), the microcontroller (MCU) adjusts the circuit and motor operation, such as reducing its power or even interrupting its operation.

[0030] In addition, the circuit also includes a circuit pin P1. Since pin P1 is located between R1 and RT1, the voltage measured at the pin is the voltage divided by RT1 with respect to the voltage of voltage source V1, and this voltage divided by RT1 is used to determine whether the circuit is in a suspended (or floating or suspended) state. The terms "suspended", "floating" and "suspended" are understood in a broad sense in the electrical field. For example, a poor solder joint or a disconnection of pin P1 will cause the circuit to be suspended or floating; and a disconnection, a short circuit, damage, operation under abnormal conditions or abnormal operation of RT1 will cause RT1 to float. For example, when the resistance value of RT1 becomes extremely large with changes in temperature and is close to a short circuit, RT1 can be considered to be in a floating state.

[0031] The circuit also includes a detection point TP1, which serves as a test point for the circuit. Since point TP1 is located between R1 and RT1, the voltage measured at point TP1 is actually the voltage divided by RT1 from the voltage of voltage source V1. The microcontroller unit (MCU) can calibrate the voltage of voltage source V1 and determine the floating state of pin P1 and RT1 based on the voltage divided value detected at point TP1. In addition, the microcontroller unit (MCU) has an analog-to-digital converter (ADC), which determines the resistance value of RT1 and thus the temperature based on the voltage divided value detected at point TP1. RT1 detects the temperature of the power device itself or the ambient temperature nearby. This temperature may be referred to as the ambient temperature or simply the temperature in this article. The voltage divided value measured at test point TP1 is represented by the symbol Temp_FET in the figure.

[0032] As mentioned above, the resistance value of RT1 varies with temperature, and the divided voltage of the power supply voltage detected at the test point TP1 is not a constant value, so the micro control unit cannot perform the above function.

[0033] Voltage source V1 can provide any voltage to the circuit depending on the application, such as a voltage range of 1V (volts) to 5V, a voltage range of 2V to 6V, or 3V, 4V, 3.3V, 4.5V, 5V, 5.3V, etc. Similarly, resistors R1 and RT1 can have any suitable resistance values. For example, the resistance of R1 can be in the range of 10KΩ (ohms) to 30KΩ, such as 15KΩ, 20KΩ, 21KΩ, 25KΩ, etc., and the resistance of RT1 can be in the range of 20KΩ (ohms) to 40KΩ, such as 25KΩ, 30KΩ, 31KΩ, 33KΩ, 35KΩ, etc. Capacitor C1 can have any suitable capacitance value, such as a range of 0.001μF to 0.05μF, such as 0.005μF, 0.01μF, etc. Note that the above voltage, resistance, and capacitance values ​​are merely examples and are not limiting. Those skilled in the art can select various suitable values ​​based on specific applications.

[0034] The circuit in Figure 2 is described below using V1 as 3.3V, R1 as 20kΩ, RT1 as 33kΩ, and C1 as 0.01μF as an example. RT1 is an NTC thermistor connected in series with R1 between voltage source V1 and ground G1. Therefore, the voltage Temp_FET measured at point TP1 represents the voltage divider value of RT1. The resistance value of RT1, 33kΩ, refers to the resistance value at a specified temperature, such as room temperature, normal operating state, initial operating state, or before operation begins, such as 20°C or 25°C. Its resistance value decreases with increasing temperature and increases with decreasing temperature. At the specified temperature, the voltage divider value Temp_FET of RT1 measured at TP1 is 2.05V. As temperature increases, the resistance value of RT1 decreases, and the voltage divider value Temp_FET also decreases accordingly. As temperature decreases, the resistance value of RT1 increases, and the voltage divider value Temp_FET also increases accordingly. The ADC detects the voltage divider value Temp_FET at TP1 and uses this voltage divider value and the fixed resistance value of R1 to calculate the resistance value of RT1. Furthermore, the temperature detected by RT1 is determined by the relationship between the resistance value of RT1 and the temperature. However, the ADC's inherent voltage detection range is limited, with an upper and lower limit, so the detected temperature also falls within a temperature range. If the voltage at TP1 exceeds this range, for example, if it exceeds the ADC's own monitoring range, the ADC will be unable to accurately determine the voltage value at TP1 and the corresponding temperature.

[0035] In this example, the MCU's voltage range upper limit is 2.4V. Considering that RT1's resistance changes with temperature, when the temperature drops to 15°C, RT1's resistance increases to a certain value. At this point, RT1's voltage divider increases from 2.05V at the specified temperature to 2.4V. 2.4V is the upper range limit of the MCU's ADC. As the temperature drops further from 15°C, RT1's resistance increases further, and its voltage divider, Temp_FET, increases further from 2.4V, exceeding the upper limit of the MCU's monitoring range and exceeding its range. Therefore, the lowest temperature the MCU can monitor is 15°C. Similarly, the MCU has a certain lower voltage limit, and accordingly, the maximum temperature it can monitor is 125°C. Therefore, the MCU can only monitor temperatures between 15°C and 125°C.

[0036] It should be pointed out that the voltage range and temperature monitoring range of the MCU are only examples for illustration and are not restrictive. In addition, RT1 is not necessarily an NTC (negative temperature coefficient) thermistor, but can also be a PTC (positive temperature coefficient) thermistor.

[0037] In view of the above-mentioned shortcomings and problems, the present invention proposes an improved circuit, namely, a first embodiment of the circuit shown in FIG3 . Compared to the circuit of FIG2 , FIG3 adds a resistor R2 with a fixed resistance value and a transistor Q1. Resistor R2 and transistor Q1 are electrically connected in parallel with RT1. Transistor Q1 acts as a switching element and can be turned on and off. Transistor Q1 can be a diode, a triode, a field-effect transistor, a thyristor, or any combination thereof, and is used to control the on / off state of the circuit. When transistor Q1 is on, its resistance is very small and negligible, thereby directly electrically connecting resistor R2 between voltage source V1 and ground G1. In this case, resistor R2 is connected in parallel with RT1. When transistor Q1 is off, its resistance is very large, thereby placing resistor R1 in an open circuit state. A drive circuit for controlling transistor Q1 is provided on the left side of transistor Q1. The drive circuit is connected to the input or control terminal of transistor Q1, which is used to control the on / off state of the transistor and can be, for example, the base. The drive circuit includes resistors R3 and R4, and capacitor C2, electrically connected between ground G1 and the transistor's input. R4 is connected between the transistor's input and ground G1. R3 and C2 are connected in series between the transistor's input and ground G1, and R3 and C2 are connected in parallel with R4. The MCU controls the drive circuit to turn transistor Q1 on and off.

[0038] As described above, similar to resistors R1 and RT1, the resistance values ​​of resistors R2, R3, and R4 can be any suitable resistance value. For example, if R2 has a resistance value of 20 kΩ, when transistor Q1 is turned on, resistors R2 and RT1 are connected in parallel between resistor R1 and ground. Then, they are connected in series with R1 between voltage source V1 and ground G1. At this point, the voltage measured at TP1 is the voltage divided by the total resistance of R2 and RT1 in parallel. At the same temperature, the total resistance of R2 and RT1 in parallel is smaller than the voltage divided by RT1 alone, thus reducing the voltage divided. Thus, even if the temperature drops below 15°C, despite the increase in RT1's resistance, the voltage divided by R2 in parallel remains within the MCU's voltage range. This allows the MCU to monitor temperatures below 15°C, thus expanding the temperature monitoring range. The expanded temperature monitoring range is specifically determined by the resistance value of resistor R2. The lower the resistance value of R2, the smaller the total resistance value after it is connected in parallel with RT1, and the smaller the voltage divider value measured at TP1, so that a larger temperature range can be detected.

[0039] In this example, R2 has a resistance of 20 kΩ, expanding the MCU's temperature monitoring range to -40°C to 125°C. Specifically, compared to the circuit in Figure 2, when the temperature drops below 15°C, the MCU turns on transistor Q1, connecting R2 in parallel with RT1. This reduces the voltage divider value Temp_FET, which would have exceeded the 2.4V limit at temperatures below 15°C in Figure 2, to below 2.4V in Figure 3. This allows the voltage divider value Temp_FET to remain within the MCU's range even if the temperature continues to drop a certain amount from 15°C.

[0040] However, as described above with reference to FIG2 , since the resistance value of RT1 varies with temperature, the embodiment of FIG3 still cannot perform the following functions: calibrating the voltage of the voltage source V1 ; determining the floating state of the pin P1 ; and determining the floating state of the resistor RT1 .

[0041] FIG4 shows a second embodiment of the circuit. Compared to the circuit of FIG3 , FIG4 adds a transistor Q2, which is connected in series between the resistor RT1 and the ground G1. Transistor Q2 is substantially the same as transistor Q1, as described above and will not be repeated here. Similar to transistor Q1, transistor Q2 also has a drive circuit, which is connected to the input terminal or control terminal of transistor Q2 and includes R5 and a resistor R6 electrically connected between the ground G1 and the input terminal of the transistor, wherein R5 is connected between the input terminal of the transistor and the drive network (not shown) of the MCU. As described above, similar to resistors R1 and RT1, the resistance values ​​of resistors R5 and R6 can be any suitable resistance value. For example, R5 can be 1KΩ and R6 can be 200KΩ. Similarly, the MCU controls the on and off of transistor Q2 by controlling the drive circuit.

[0042] By adding transistor Q2, RT1 can be disconnected, so that the influence of the resistance change of RT1 can be eliminated at certain moments, thereby achieving functions that cannot be achieved in Figures 2 and 3.

[0043] As shown in FIG5 , the operation process of the circuit of FIG4 includes the following steps.

[0044] Step S1: When the circuit starts, Q1 and Q2 are turned off, disconnecting both R2 and RT1. The voltage at TP1, Temp_FET, is then detected. If it is 3.3V (i.e., the voltage of voltage source V1), the MCU is operating normally, indicating that the ADC channel is functioning properly, and the process proceeds to step S2. Otherwise, the ADC channel is malfunctioning and requires repair. It should be noted that step S1 also checks the floating state of pin P1; malfunctioning ADC channels indicates that pin P1 is floating.

[0045] Step S2: Turn on Q1, turn off Q2, detect the voltage value Temp_FET at TP1, and calibrate the voltage of voltage source V1 to see if it is 3.3V. If so, the process proceeds to step S3. The specific calibration process is as follows: Turning off Q2 causes RT1 to be disconnected, and turning on Q1 causes R2 and R1 to be connected in series between voltage source V1 and ground G1. Since the resistance values ​​of R1 and R2 are equal, the voltage divider value Temp_FET at TP1 is half of the voltage source V1. In other words, if the voltage divider value Temp_FET is 1.65V, it indicates that the voltage of voltage source V1 is 3.3V, and the calibration is successful.

[0046] Step S3: Turn on Q1 and Q2. At this point, R2 and RT1 are connected in parallel between R1 and ground G1. The voltage value Temp_FET at TP1 is detected to determine whether the voltage of the voltage value Temp_FET is greater than a predetermined value. If not, the process proceeds to step S4. The purpose of step S3 is to detect whether RT1 is in a floating state. Specifically, the voltage value Temp_FET is actually the voltage divider value of the total resistance of RT1 and R2 in parallel. If RT1 is an NTC resistor, the resistance value of RT1 increases as the temperature decreases. When the temperature detected or experienced by RT1 is within a predetermined temperature range, the resistance value of RT1 has a predetermined upper limit. However, when the temperature exceeds a certain threshold and decreases, the resistance value of RT1 increases, approaching infinity, which is equivalent to being disconnected. At this time, RT1 is in a floating state.

[0047] Based on this, the temperature detected by RT1 is set within a predetermined temperature range according to the specific application. When RT1 is at the predetermined temperature threshold, the resistance value of RT1 is at the predetermined upper limit, and the voltage value Temp_FET is at the aforementioned predetermined value. When the temperature detected by RT1 exceeds the predetermined temperature range, the resistance value of RT1 exceeds the predetermined upper limit, and the voltage value Temp_FET exceeds the aforementioned predetermined voltage value. Therefore, when the voltage value Temp_FET is detected to be greater than the predetermined value in step S3, it indicates that RT1 is in an abnormal floating state, that is, the temperature exceeds the predetermined range; if the voltage value Temp_FET is not greater than the predetermined value, it indicates that RT1 is in a normal state. In addition, when the voltage value Temp_FET is zero volts, it indicates that RT1 is short-circuited.

[0048] Step S4: Turn off Q1 and turn on Q2. At this point, R2 is disconnected, and RT1 and R1 are electrically connected in series between voltage source V1 and ground G1. The voltage value Temp_FET at TP1 is detected. This voltage value is actually the voltage divider value of RT1. The resistance value of RT1 at this time is calculated based on this voltage divider value. The resistance-temperature relationship of RT1 is then used to calculate the ambient temperature detected by RT1 or the ambient temperature in which RT1 is located.

[0049] As described above based on the example of Figure 2, the upper limit value of the voltage value Temp_FET monitored by the MCU is 2.4V. Therefore, if the voltage value Temp_FET detected at this time exceeds 2.4V, it indicates that the resistance value of RT1 increases and exceeds the upper limit threshold as the temperature decreases, that is, the monitored temperature at this time drops beyond the predetermined range and the actual temperature at this time cannot be accurately known. It is necessary to reduce the voltage divider value of RT1 and increase the temperature monitoring range. At this time, the process needs to proceed to step S5.

[0050] Step S5: Connect Q1 and Q2. At this point, R2 and RT1 are connected in parallel between R1 and ground G1. The voltage value Temp_FET at TP1 is detected, and the current lower temperature of RT1 is calculated. In step S5, the parallel connection of R2 and RT1 reduces the total resistance, thereby reducing the voltage divider value Temp_FET at TP1. Specifically, compared to the low-temperature voltage Temp_FET at step S4, which exceeded 2.4V, the addition of R2 in parallel with RT1 reduces the voltage value Temp_FET from 2.4V, bringing it within the MCU's measurement range.

[0051] It should be noted that the above steps S1-S5 do not have to be executed sequentially or simultaneously in the order described. Instead, these steps are independent of each other to achieve different functions. Therefore, these steps can be executed separately, in any order, or some of them can be combined and executed in any order. In other words, the MCU can selectively execute one or more of steps S1-S5 based on the control logic.

[0052] Before the motor 10 runs, the MCU needs to perform a floating check on the pin P1 (eg, step S1 ); and after the motor runs, the MCU will continue to perform a floating check on the pin P1 .

[0053] Before the motor 10 runs, the MCU needs to calibrate the voltage of the voltage source V1 (eg, step S2 ); and after the motor runs, the MCU may no longer perform calibration.

[0054] Before the motor 10 runs, the MCU needs to perform a floating check and / or a short circuit check on RT1 (eg, step S3 ); and after the motor runs, the MCU will continue to perform a floating check and / or a short circuit check on it.

[0055] During the operation of the motor 10, the MCU needs to monitor the temperature of the power device detected by RT1 and / or the ambient temperature (e.g., steps S4 and / or S5). The ambient temperature can usually be detected by step S4, wherein R2 is disconnected and the ambient temperature is determined only by the voltage divider value of RT1. In this case, the temperature range monitored by the MCU is, for example, 15°C to 125°C. When the ambient temperature is lower than 15°C, the MCU switches to step S5, wherein R2 and RT1 are connected in parallel, and the ambient temperature is determined by the voltage divider value of the total resistance of the parallel connection. In this case, the temperature range monitored by the MCU is, for example, -40°C (minus 40°C) to 125°C.

[0056] Furthermore, it should be noted that the various resistance values, voltage values, capacitance values, and temperature values ​​listed herein are examples, intended to illustrate the concepts of the present invention, and are not intended to be limiting. Those skilled in the art may appropriately set these values ​​based on specific applications. While RT1 is described as an NTC resistor, RT1 may be a PTC resistor, all of which are applicable to the concepts of the present invention and fall within the scope of protection of the present invention.

[0057] In addition, a control system is also provided. The control system is used to execute the circuit operation method of the present invention, and the control system selectively executes one or more of steps S1-S5 according to control logic.

[0058] The detection circuit and operating method of the present invention can implement voltage calibration of a voltage source, can implement floating detection of circuit pins, can also implement floating detection and / or short circuit detection of a temperature-sensitive resistor in the circuit, and can also expand the temperature monitoring range of the temperature-sensitive resistor. The detection circuit of the present invention has a simple structure, is easy to operate, is low in cost, can implement multiple functions, has good versatility, and can be applied to various tools and / or motors, such as power tools and their motors.

[0059] Although specific embodiments of the present invention have been described above, those skilled in the art will appreciate that these are merely illustrative and that the scope of the present invention is defined by the appended claims. Those skilled in the art may make various combinations, variations, or modifications to these embodiments without departing from the principles and essence of the present invention, and such combinations, variations, and modifications are intended to fall within the scope of the present invention.

Claims

1. A detection circuit comprising: Voltage source (V1); Ground (G1); a first resistor (R1), wherein a first end of the first resistor (R1) is connected to the voltage source (V1); a thermistor (RT1), wherein a first end of the thermistor (RT1) is connected to a second end of the first resistor (R1); a second resistor (R2), wherein a first end of the second resistor (R2) is connected to a connection point between the thermistor (RT1) and the first resistor (R1); a first switching element (Q1), the first switching element (Q1) being connected between the second end of the second resistor (R2) and the ground (G1); A second switching element (Q2), the second switching element (Q2) is connected between a second end of the thermistor (RT1) and the ground (G1).

2. The detection circuit according to claim 1, wherein: The first switching element (Q1) and the second switching element (Q2) are transistors.

3. The detection circuit according to claim 1, wherein: The thermistor (RT1) is a negative temperature coefficient thermistor.

4. The detection circuit according to claim 1, wherein: The detection circuit further includes a pin (P1) located between the first resistor (R1) and the thermistor (RT1).

5. The detection circuit according to claim 1, wherein: The detection circuit further includes a first capacitor (C1) connected in parallel with the thermistor (RT1) between the first resistor (R1) and the ground (G1). The detection circuit according to claim 1 , wherein: The detection circuit also includes a drive circuit for controlling the first switching element (Q1), the drive circuit including: a third resistor (R3) and a second capacitor (C2), the third resistor (R3) and the second capacitor (C2) being sequentially connected between the control end of the first switching element (Q1) and the ground (G1); and a fourth resistor (R4), the fourth resistor (R4) being connected in parallel with the third resistor (R3) and the second capacitor (C2) between the control end of the first switching element (Q1) and the ground (G1).

7. The detection circuit according to claim 1, wherein: The detection circuit further includes a drive circuit for controlling the second switch element (Q2), the drive circuit including: a fifth resistor (R5), the fifth resistor (R5) being connected between the control end of the second switch element (Q2) and a controller of the detection circuit; and a sixth resistor (R6), the sixth resistor (R6) being connected between the control end of the second switch element (Q2) and the ground (G1).

8. A method for operating the detection circuit according to any one of claims 1 to 7, the method comprising the step of turning off the first switching element (Q1) and the second switching element (Q2) to detect a voltage value at a connection point between the thermistor (RT1) and the first resistor (R1).

9. The method according to claim 8, wherein The method further includes the steps of turning on the first switching element (Q1) and turning off the second switching element (Q2) to detect a voltage value at a connection point between the thermistor (RT1) and the first resistor (R1).

10. The method according to claim 8, wherein The method further includes the step of turning on the first switching element (Q1) and the second switching element (Q2) to detect a voltage value at a connection point between the thermistor (RT1) and the first resistor (R1).

11. The method according to claim 8, wherein The method further includes the steps of turning off the first switching element (Q1) and turning on the second switching element (Q2) to detect a voltage value at a connection point between the thermistor (RT1) and the first resistor (R1).

12. The method according to claim 11, wherein The method further includes the step of turning off the first switching element (Q1) and turning on the second switching element (Q2), and when the voltage value at the connection point between the thermistor (RT1) and the first resistor (R1) exceeds a predetermined value, turning on the first switching element (Q1) to detect the voltage value at the connection point between the thermistor (RT1) and the first resistor (R1).

13. The method according to any one of claims 8 to 12, wherein The method further includes selectively executing one or more of the steps according to control logic.

14. A control system for executing the method according to any one of claims 8 to 13, wherein: The control system selectively executes one or more of the steps according to control logic.

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