Contactor detection circuit

Abstract

A contactor detection circuit is disclosed. [Solution] The contactor detection circuit is configured such that the output terminal of a reference voltage generation circuit is connected to the inverting input terminal of the comparator and electrically connected to the two fixed contacts of the contactor in order to input a reference voltage V1 to the inverting input terminal of the comparator. The output terminal of a sampling circuit is connected to the common-mode input terminal of the comparator and the output terminal of a waveform generator is connected to the input terminal of the sampling circuit in order to input a sampling voltage V2 to the common-mode input terminal of the comparator. A periodically changing voltage signal V3 is input to the sampling circuit. When the contactor is open, the sampling voltage V2 output by the sampling circuit is a periodic waveform, causing the comparator to output a periodic square wave signal. When the contactor is closed, the sampling voltage V2 output by the sampling circuit is higher than the reference voltage V1, causing the comparator to output a high level.

Description

Technical Field

[0001] Cross - reference to Related Applications This application claims the benefit of Chinese Patent Application No. CN202411291252.4, filed with the China National Intellectual Property Administration on September 13, 2024, the entire disclosure of which is incorporated herein by reference.

[0002] The present invention relates to a contact detection circuit.

Background Art

[0003] High - voltage contacts are important components of high - voltage power distribution systems, and the detection of the contact state is a very important safety function. Currently, there are two main detection methods for contacts. One method is to use a high - voltage source as a sampling input and determine the state of the contact by voltage - division sampling. The disadvantage of the first solution is that in order to achieve insulation between high voltage and low voltage, insulation of the power supply and insulation of the operational amplifier are required, which is costly. In addition, the first method relies on a high - voltage source as a sampling input and needs to recognize the voltage of the high voltage in real time, which is inconvenient for actual applications. The second solution is to use a PWM wave generated by a microcontroller unit (MCU) to achieve insulation between high voltage and low voltage by means of a Y - capacitor. The disadvantage of the second solution is that it requires the development of an MCU and software, resulting in high costs.

Summary of the Invention

Problems to be Solved by the Invention

[0004] The present invention is made to overcome or mitigate at least one aspect of the above - mentioned disadvantages.

Means for Solving the Problems

[0005] According to an aspect of the present invention, a contactor detection circuit is provided. The contactor detection circuit comprises a comparator; a reference voltage generation circuit, the output terminal of which is connected to the inverting input terminal of the comparator for inputting a reference voltage V1 to the inverting input terminal of the comparator; a sampling circuit, electrically connected to two fixed contacts of the contactor, the output terminal of which is connected to the common-mode input terminal of the comparator for inputting a sampling voltage V2 to the common-mode input terminal of the comparator; and a waveform generator, the output terminal of which is connected to the input terminal of the sampling circuit, and used to input a periodically changing voltage signal V3 to the sampling circuit. When the contactor is open, the sampling voltage V2 output by the sampling circuit is a periodic waveform, causing the comparator to output a periodic square wave signal. When the contactor is closed, the sampling voltage V2 output by the sampling circuit is higher than the reference voltage V1, causing the comparator to output a high level.

[0006] According to an exemplary embodiment of the present invention, the sampling circuit includes a capacitor C1, one end of which is used to connect to one fixed contact of a contactor; a resistor R1, one end of which is grounded and the other end of which is connected to the other end of capacitor C1; a capacitor C2, one end of which is used to connect to the other fixed contact of a contactor; and a resistor R2, one end of which is connected to the output terminal of a waveform generator and the other end of which is connected to the other end of capacitor C2 and the common-mode input terminal of a comparator. One end of resistor R2 functions as the input terminal of the sampling circuit, and the other end of resistor R2 functions as the output terminal of the sampling circuit.

[0007] According to another exemplary embodiment of the present invention, capacitors C1 and C2 are Y capacitors used to electrically isolate a high-voltage circuit connected to two fixed contacts of the contactor.

[0008] According to another exemplary embodiment of the present invention, the sampling circuit further includes a diode D1, the positive terminal of which is connected to the other end of a resistor R2 and the other end of a capacitor C2, and the negative terminal of which is connected to the common-mode input terminal of a comparator.

[0009] According to another exemplary embodiment of the present invention, when the contactor is open, the sampling circuit is in an open-circuit state, and the sampling voltage V2 output by the sampling circuit is the output of the waveform generator minus the forward voltage drop across diode D1.

[0010] According to another exemplary embodiment of the present invention, when the contactor is closed, one end of capacitor C1 is electrically connected to one end of capacitor C2, and the output of the waveform generator is divided by resistor R1 and capacitor C1 and resistor R2 and capacitor C2, so that the sampling voltage V2 output by the sampling circuit is equal to the sum of the voltages across resistor R1, capacitor C1, and capacitor C2 (the total voltage across resistor R1, capacitor C1, and capacitor C2).

[0011] According to another exemplary embodiment of the present invention, the periodic voltage signal V3 output by the waveform generator is a waveform signal having a predetermined frequency, and the waveform signal is a square wave signal, a triangular wave signal, or a sine wave signal.

[0012] According to another exemplary embodiment of the present invention, the amplitude of the waveform signal is 2.5V, the waveform signal is forward-biased by 2.5V, and the waveform signal is periodically varied between 0V and 5V.

[0013] According to another exemplary embodiment of the present invention, the contactor detection circuit further comprises an LDO circuit having an input terminal for electrically connecting to a power supply, the output terminal of the LDO circuit being connected to the power supply terminals of the comparator, the reference voltage generation circuit, and the waveform generator in order to supply power to the comparator, the reference voltage generation circuit, and the waveform generator.

[0014] According to another exemplary embodiment of the present invention, the contactor detection circuit further comprises a power supply connected to the input terminal of the LDO circuit, wherein the output voltage of the power supply is 6 to 18V, and the output voltage of the LDO circuit is equal to 5V.

[0015] According to another exemplary embodiment of the present invention, the reference voltage generating circuit includes a resistor R4, one end of which is connected to the output terminal of an LDO circuit, and a resistor R5, one end of which is connected to the other end of resistor R4 and the inverting input of a comparator. The other end of resistor R5 is grounded, and the reference voltage V1 at the inverting input of the comparator is equal to the voltage across resistor R5 (the voltage across resistor R5).

[0016] According to another exemplary embodiment of the present invention, the output terminal of a comparator is used to connect to the input terminal of the analog-to-digital converter of the electronic control unit in order to input an analog detection voltage V4 to the analog-to-digital converter of the electronic control unit.

[0017] According to another exemplary embodiment of the present invention, the contactor detection circuit further comprises a voltage divider circuit, which is connected to the output terminal of a comparator and the input terminal of an analog-to-digital converter of an electronic control unit, and is used to divide the output of the comparator so that the analog detection voltage V4 input to the analog-to-digital converter is equal to a predetermined value.

[0018] According to another exemplary embodiment of the present invention, the voltage divider circuit includes a resistor R6, one end of which is connected to the output terminal of a comparator and the other end of which is used to electrically connect to the input terminal of an analog-to-digital converter, and a resistor R7, one end of which is connected to the other end of resistor R6. The other end of resistor R7 is grounded, and the analog sense voltage V4 input to the input terminal of the analog-to-digital converter is equal to the voltage across resistor R7 (the voltage across resistor R7).

[0019] According to another exemplary embodiment of the present invention, when the contactor is in the open state, the voltage of resistor R7 is a periodic rectangular wave signal. Therefore, the analog detection voltage V4 input to the input terminal of the analog-to-digital converter is a periodic rectangular wave signal. When the contactor is in the closed state, the voltage of resistor R7 is equal to 2V. Therefore, the analog detection voltage V4 input to the input terminal of the analog-to-digital converter is equal to 2V.

[0020] In the above exemplary embodiment according to the present invention, since there is no need to use an isolated power supply and an isolated operational amplifier, nor is it necessary to use an MCU or develop dedicated software, the cost is significantly reduced.

[0021] By explaining the exemplary embodiments of the present invention in detail while referring to the accompanying drawings, the above and other features of the present invention will become clearer.

Brief Description of the Drawings

[0022] [Figure 1] It is a circuit diagram of a contactor detection circuit according to an exemplary embodiment of the present invention when the contactor is in the open state. [Figure 2] It is a circuit diagram of a contactor detection circuit according to an exemplary embodiment of the present invention when the contactor is in the closed state. [Figure 3] It is a circuit diagram of a contactor detection circuit according to an exemplary embodiment of the present invention in which the numerical values of each electrical component are shown.

Modes for Carrying Out the Invention

[0023] Hereinafter, exemplary embodiments of the present disclosure will be described in detail while referring to the accompanying drawings. In the drawings, the same reference numerals refer to the same elements. However, the present disclosure can be embodied in many different forms and should not be construed as being limited to the embodiments described herein. Rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the concept of the present disclosure to those skilled in the art.

[0024] In the following detailed description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the disclosed embodiments. It will be apparent, however, that one or more embodiments may be practiced without these specific details. In other instances, well-known structures and devices are shown schematically in order to simplify the drawing.

[0025] According to a general concept of the present invention, a contact detector circuit is provided. The contact detector circuit includes a comparator, a reference voltage generation circuit, an output terminal of the reference voltage generation circuit being connected to an inverting input terminal of the comparator for inputting a reference voltage V1 to the inverting input terminal of the comparator, a sampling circuit, an output terminal of the sampling circuit being connected to a non-inverting input terminal of the comparator for inputting a sampling voltage V2 to the non-inverting input terminal of the comparator, the sampling circuit being electrically connected to two fixed contacts of a contact, and a waveform generator, an output terminal of the waveform generator being connected to an input terminal of the sampling circuit, the waveform generator being used for inputting a periodically changing voltage signal V3 to the sampling circuit. When the contact is in an open state, the sampling voltage V2 output by the sampling circuit is a periodic waveform, causing the comparator to output a periodic rectangular wave signal. When the contact is in a closed state, the sampling voltage V2 output by the sampling circuit is higher than the reference voltage V1, causing the comparator to output a high level.

[0026] FIG. 1 is a circuit diagram of a contact detector circuit according to an exemplary embodiment of the present invention when the contact is in an open state. FIG. 2 is a circuit diagram of a contact detector circuit according to an exemplary embodiment of the present invention when the contact is in a closed state. FIG. 3 is a circuit diagram of a contact detector circuit according to an exemplary embodiment of the present invention in which numerical values of each electrical component are shown.

[0027] As shown in Figures 1 to 3, an exemplary embodiment of the present invention discloses a contactor detection circuit. The contactor detection circuit comprises a comparator U1, a reference voltage generation circuit 2, a sampling circuit 1, and a waveform generator 3. The output terminal of the reference voltage generation circuit 2 is connected to the inverting input terminal of the comparator U1 to input a reference voltage V1 to the inverting input terminal of the comparator U1. The sampling circuit 1 is electrically connected to two fixed contacts of the contactor S1, and the output terminal of the sampling circuit 1 is connected to the common-mode input terminal of the comparator U1 to input a sampling voltage V2 to the common-mode input terminal of the comparator U1. The output terminal of the waveform generator 3 is connected to the input terminal of the sampling circuit 1 to input a periodic voltage signal V3 to the sampling circuit 1.

[0028] As shown in Figures 1 to 3, in the illustrated embodiment, when the contactor S1 is in the open state, the sampling voltage V2 output by the sampling circuit 1 is a periodic waveform, causing the comparator U1 to output a periodic square wave signal. When the contactor S1 is in the closed state, the sampling voltage V2 output by the sampling circuit 1 is higher than the reference voltage V1, causing the comparator U1 to output a high level. Therefore, in the present invention, the state of the contactor S1 can be determined based on the output of the comparator U1. When the comparator U1 outputs a periodic square wave signal, it can be determined that the contactor S1 is in the open state. When the comparator U1 outputs a high level, it can be determined that the contactor S1 is in the closed state.

[0029] As shown in Figures 1 to 3, in the illustrated embodiment, the sampling circuit 1 includes a capacitor C1, a resistor R1, a capacitor C2, and a resistor R2. One end of capacitor C1 is used to connect to one fixed contact of contactor S1 (i.e., one fixed contact point of the contactor). One end of resistor R1 is grounded, and the other end is connected to the other end of capacitor C1. One end of capacitor C2 is used to connect to the other fixed contact of contactor S1 (i.e., the other fixed contact point of the contactor). One end of resistor R2 is connected to the output terminal of waveform generator 3, and the other end is connected to the other end of capacitor C2 and the common-mode input terminal of comparator U1. In the illustrated embodiment, one end of resistor R2 functions as the input terminal of the sampling circuit 1, and the other end of resistor R2 functions as the output terminal of the sampling circuit 1.

[0030] As shown in Figures 1 to 3, in the illustrated embodiment, capacitors C1 and C2 are Y capacitors used to electrically isolate the high-voltage circuit 6 connected to the two fixed contacts of the contactor S1. In this way, reliable isolation between high voltage and low voltage can be achieved, improving safety during use.

[0031] As shown in Figures 1 to 3, in the illustrated embodiment, the sampling circuit 1 further includes a diode D1. The positive terminal of diode D1 is connected to the other end of resistor R2 and the other end of capacitor C2, and the negative terminal of diode D1 is connected to the common-mode input terminal of comparator U1.

[0032] As shown in Figures 1 to 3, in the illustrated embodiment, when the contactor S1 is open, the sampling circuit 1 is also open, and the voltage drop across resistor R2 is approximately zero. Therefore, the sampling voltage V2 output by the sampling circuit 1 is equal to the output of the waveform generator 3 minus the forward voltage drop across diode D1. At this time, the sampling voltage V2 output by the sampling circuit 1 is the periodic voltage signal V3 minus the forward voltage drop across diode D1.

[0033] As shown in Figures 1 to 3, in the illustrated embodiment, when the contactor S1 is in the closed state, one end of capacitor C1 is electrically connected to one end of capacitor C2. The output of the waveform generator 3 is divided by resistor R1 and capacitor C1 and resistor R2 and capacitor C2. Therefore, the sampling voltage V2 output by the sampling circuit 1 is equal to the sum of the voltages across resistor R1, capacitor C1, and capacitor C2 (the total voltage across resistor R1, capacitor C1, and capacitor C2).

[0034] As shown in Figures 1 to 3, in the illustrated embodiment, the periodic voltage signal V3 output by the waveform generator 3 is a waveform signal having a predetermined frequency, and the waveform signal may be a square wave signal, a triangular wave signal, a sine wave signal, or any other suitable waveform signal.

[0035] As shown in Figures 1 to 3, in the illustrated embodiment, the amplitude of the waveform signal is 2.5V, the waveform signal is forward-biased by 2.5V, and the waveform signal is periodically varied between 0V and 5V.

[0036] As shown in Figures 1 to 3, in the illustrated embodiment, the contactor detection circuit further comprises an LDO (low dropout regulator) circuit 5. The input terminal of the LDO circuit 5 is used to electrically connect to a power supply 8. The output terminal of the LDO circuit 5 is connected to the power supply terminals of the comparator U1, the reference voltage generation circuit 2, and the waveform generator 3, and is used to supply power to the comparator U1, the reference voltage generation circuit 2, and the waveform generator 3. In the illustrated embodiment, the LDO circuit 5 can supply a stable 5V voltage to the comparator U1, the reference voltage generation circuit 2, and the waveform generator 3.

[0037] As shown in Figures 1 to 3, in the illustrated embodiment, the contactor detection circuit further comprises a power supply 8 connected to the input terminal of the LDO circuit 5. The output voltage of the power supply 8 is 6 to 18V, and the output voltage of the LDO circuit 5 is equal to 5V. The output voltage of the power supply 8 can vary between 6 and 18V, but the LDO circuit 5 can ensure that its output voltage is always equal to 5V.

[0038] As shown in Figures 1 to 3, in the illustrated embodiment, the reference voltage generation circuit 2 includes resistors R4 and R5. One end of resistor R4 is connected to the output terminal of the LDO circuit 5. One end of resistor R5 is connected to the other end of resistor R4 and the inverting input of comparator U1. The other end of resistor R5 is grounded, and the reference voltage V1 at the inverting input of comparator U1 is equal to the voltage across resistor R5 (voltage across resistor R5).

[0039] As shown in Figures 1 to 3, in the illustrated embodiment, the output terminal of comparator U1 is used to connect to the input terminal of the analog-to-digital converter 7 of the electronic control unit in order to input the analog detection voltage V4 to the analog-to-digital converter 7 of the electronic control unit.

[0040] As shown in Figures 1 to 3, in the illustrated embodiment, the contactor detection circuit further comprises a voltage divider circuit 4, which is connected to the output terminal of comparator U1 and the input terminal of the analog-to-digital converter 7 of the electronic control unit, and divides the output of comparator U1 so that the analog detection voltage V4 input to the analog-to-digital converter 7 is equal to a predetermined value. In the illustrated embodiment, the simulated detection voltage V4 is equal to 2V.

[0041] As shown in Figures 1 to 3, in the illustrated embodiment, the voltage divider circuit 4 includes resistors R6 and R7. One end of resistor R6 is connected to the output terminal of comparator U1, and the other end is used to electrically connect to the input terminal of analog-to-digital converter 7. One end of resistor R7 is connected to the other end of resistor R6. The other end of resistor R7 is grounded, and the analog detection voltage V4 at the input of analog-to-digital converter 7 is equal to the voltage across resistor R7 (voltage across resistor R7).

[0042] As shown in Figures 1 to 3, in the illustrated embodiment, when the contactor S1 is in the open state, the voltage across resistor R7 is a periodic square wave signal, and therefore the analog detection voltage V4 at the input terminal of the analog-to-digital converter 7 is a periodic square wave signal. When the contactor S1 is in the closed state, the voltage across resistor R7 (voltage across resistor R7) is equal to 2V, and the analog detection voltage V4 at the input of the analog-to-digital converter 7 is equal to 2V. Therefore, in the illustrated embodiment, the state of the contactor S1 can be determined based on the analog detection voltage V4. When the simulated detection voltage V4 is a periodic square wave signal, it can be determined that the contactor S1 is in the open state. When the simulated detection voltage V4 is equal to 2V, it can be determined that the contactor S1 is in the closed state.

[0043] Figure 3 shows the specific numerical values ​​of each electronic component in the contactor detection circuit. However, the present invention is not limited to the illustrated embodiment, and the specific numerical values ​​of each electronic component in the contactor detection circuit can be adjusted according to the actual situation.

[0044] Those skilled in the art should understand that the embodiments described above are illustrative and not limiting. For example, those skilled in the art can make many modifications to the embodiments described above without structural or principle contradictions, and can freely combine the various features described in different embodiments.

[0045] While several exemplary embodiments have been illustrated and described, it will be understood by those skilled in the art that various modifications or changes can be made to these embodiments without departing from the principles and spirit of this disclosure. The scope of this disclosure is defined in the claims and its equivalents.

[0046] When used herein, elements described in the singular form and preceded by the word "a" or "an" should be understood not to exclude the plural forms of such elements or steps unless it is explicitly stated that such exclusion is to be excluded. Furthermore, references to “one embodiment” of the present invention are not intended to be construed as excluding the existence of additional embodiments that likewise incorporate the described features. Moreover, unless it is expressly stated otherwise, embodiments that “compile” or “have” one or more elements having a particular characteristic may include additional such elements that do not possess that characteristic.

Claims

1. A contactor detection circuit, Comparator (U1), A reference voltage generation circuit (2) is provided, and the output terminal of the reference voltage generation circuit (2) is connected to the inverting input terminal of the comparator (U1) in order to input a reference voltage V1 to the inverting input terminal of the comparator (U1), A sampling circuit (1) is electrically connected to two fixed contacts of a contactor (S1) to input a sampling voltage V2 to the common-mode input terminal of the comparator (U1), and the output terminal of the sampling circuit (1) is connected to the common-mode input terminal of the comparator (U1). A waveform generator (3) is provided, the output terminal of which is connected to the input terminal of the sampling circuit (1), and is used to input a periodically changing voltage signal V3 to the sampling circuit (1). Equipped with, When the contactor (S1) is in the open state, the sampling voltage V2 output by the sampling circuit (1) is a periodic waveform, causing the comparator (U1) to output a periodic square wave signal. A contactor detection circuit in which, when the contactor (S1) is in a closed state, the sampling voltage V2 output by the sampling circuit (1) is higher than the reference voltage V1, causing the comparator (U1) to output a high level.

2. The sampling circuit (1) is A capacitor C1, one end of which is used to connect to one fixed contact of the contactor (S1), A resistor R1, with one end grounded and the other end connected to the other end of the capacitor C1, A capacitor C2, one end of which is used to connect to the other fixed contact of the contactor (S1), A resistor R2, one end of which is connected to the output terminal of the waveform generator (3), and the other end of which is connected to the other end of the capacitor C2 and the common-mode input terminal of the comparator (U1), and Includes, The contactor detection circuit according to claim 1, wherein one end of the resistor R2 functions as the input terminal of the sampling circuit (1), and the other end of the resistor R2 functions as the output terminal of the sampling circuit (1).

3. The contactor detection circuit according to claim 2, wherein the capacitors C1 and C2 are Y capacitors used to electrically isolate the high-voltage circuit (6) connected to the two fixed contacts of the contactor (S1).

4. The contactor detection circuit according to claim 2, wherein the sampling circuit (1) further includes a diode D1, the positive terminal of the diode D1 being connected to the other end of the resistor R2 and the other end of the capacitor C2, and the negative terminal of the diode D1 being connected to the common-mode input terminal of the comparator (U1).

5. The contactor detection circuit according to claim 4, wherein when the contactor (S1) is in the open state, the sampling circuit (1) is in an open circuit state, and the sampling voltage V2 output by the sampling circuit (1) is obtained by subtracting the forward voltage drop of the diode D1 from the output of the waveform generator (3).

6. The contactor detection circuit according to claim 2, wherein when the contactor (S1) is in the closed state, one end of the capacitor C1 is electrically connected to one end of the capacitor C2, the output of the waveform generator (3) is divided by the resistor R1 and the capacitor C1 and the resistor R2 and the capacitor C2, and therefore the sampling voltage V2 output by the sampling circuit (1) is equal to the sum of the voltages across the resistor R1, the capacitor C1, and the capacitor C2.

7. The contactor detection circuit according to claim 1, wherein the periodic voltage signal V3 output by the waveform generator (3) is a waveform signal having a predetermined frequency, and the waveform signal is a square wave signal, a triangular wave signal, or a sine wave signal.

8. The contactor detection circuit according to claim 7, wherein the amplitude of the waveform signal is 2.5V, the waveform signal is forward-biased by 2.5V, and the waveform signal is periodically varied between 0V and 5V.

9. The LDO circuit (5) further comprises an input terminal for electrically connecting to a power supply (8), The contactor detection circuit according to claim 1, wherein the output terminal of the LDO circuit (5) is connected to the power supply terminals of the comparator (U1), the reference voltage generation circuit (2), and the waveform generator (3) in order to supply power to the comparator (U1), the reference voltage generation circuit (2), and the waveform generator (3).

10. The LDO circuit (5) is further provided with a power supply (8) connected to the input terminal, The contactor detection circuit according to claim 9, wherein the output voltage of the power supply (8) is 6 to 18V, and the output voltage of the LDO circuit (5) is equal to 5V.

11. The aforementioned reference voltage generation circuit (2) is A resistor R4, one end of which is connected to the output terminal of the LDO circuit (5), A resistor R5, wherein one end of the resistor R5 is connected to the other end of the resistor R4 and the inverting input terminal of the comparator (U1), and Includes, The contactor detection circuit according to claim 9, wherein the other end of the resistor R5 is grounded, and the reference voltage V1 at the inverting input terminal of the comparator (U1) is equal to the voltage across the resistor R5.

12. The contactor detection circuit according to any one of claims 1 to 11, wherein the output terminal of the comparator (U1) is used to connect to the input terminal of the analog-to-digital converter (7) of the electronic control unit in order to input an analog detection voltage V4 to the analog-to-digital converter (7) of the electronic control unit.

13. The contactor detection circuit according to claim 12, further comprising a voltage divider circuit (4), the voltage divider circuit (4) being connected to the output terminal of the comparator (U1) and the input terminal of the analog-to-digital converter (7) of the electronic control unit, and used to divide the output of the comparator (U1) so that the analog detection voltage V4 input to the analog-to-digital converter (7) is equal to a predetermined value.

14. The aforementioned voltage divider circuit (4) is A resistor R6, one end of which is connected to the output terminal of the comparator (U1) and the other end of which is used to electrically connect to the input terminal of the analog-to-digital converter (7), A resistor R7, wherein one end of the resistor R7 is connected to the other end of the resistor R6. Includes, The contactor detection circuit according to claim 13, wherein the other end of the resistor R7 is grounded, and the analog detection voltage V4 input to the input terminal of the analog-to-digital converter (7) is equal to the voltage across the resistor R7.

15. When the contactor (S1) is in the open state, the voltage across the resistor R7 is a periodic square wave signal, and therefore the analog detection voltage V4 input to the input terminal of the analog-to-digital converter (7) is a periodic square wave signal. The contactor detection circuit according to claim 14, wherein when the contactor (S1) is in the closed state, the voltage across the resistor R7 is equal to 2V, and therefore the analog detection voltage V4 input to the input terminal of the analog-to-digital converter (7) is equal to 2V.

Images