Voltage protection circuit capable of sampling positive and negative power supplies

Abstract

The invention discloses a voltage protection circuit capable of sampling positive and negative power supplies. The voltage protection circuit comprises a voltage sampling circuit, a sampling voltage conversion and amplification circuit, a comparison circuit and a fault indication and protection circuit, the voltage sampling circuit is used for collecting voltage signals of a protection sampling point of the high-voltage pulse modulator, and the output end of the voltage sampling circuit is connected to the sampling voltage conversion and discharge circuit; the sampling voltage conversion and amplification circuit is used for amplifying the sampled voltage and sending the amplified voltage into the comparison circuit or converting the sampled negative voltage into positive voltage, amplifying the positive voltage and sending the amplified positive voltage into the comparison circuit; the comparison circuit compares the received voltage with a threshold value and outputs a voltage fault signal to the fault indication and protection circuit according to a comparison result; the fault indication and protection circuit is used for sending out fault indication information and a fault protection signal. According to the invention, through the design of the dial S1, the requirement of positive and negative power supply sampling is met, and through the design of the positive and negative phase voltage comparison circuits, the identification of undervoltage and overvoltage faults is realized.

Description

Technical Field

[0001] This invention relates to the field of protection circuits for high-voltage pulse modulators, and particularly to a voltage protection circuit suitable for high-voltage pulse modulators that can sample positive and negative power supplies. Background Technology

[0002] With the continuous development of high-power pulse technology and the increasing output energy levels, high-voltage pulse modulators, as the core energy component of high-power microwave sources, are particularly important in providing pulse waveforms with high stability, high reliability, and high power density. Multi-primary solid-state pulse modulators abandon the traditional design of a single large energy storage and switch, employing N identical, relatively low-power solid-state switching units to achieve energy superposition. DC energy is simultaneously distributed to N independent and identical primary module units for storage. These N energy storage units receive precise and synchronized drive signals, causing all module units to discharge synchronously. Each module unit generates a high-voltage pulse, which is then combined through a pulse transformer. The combined high-voltage energy has N times the energy of a single module unit and is applied to the load to form a high-power microwave source.

[0003] Because the module unit operates under synchronous charging and discharging conditions, the stability of the charging voltage will directly affect the stability of the final pulse waveform. Overcharging will result in excessive energy output, which may damage the energy storage and switching devices in the module unit. Undercharging will result in insufficient output energy, which may not meet the final power level requirements. Therefore, voltage protection circuits need to be designed in N independent and identical module units to sample the charging voltage and achieve fault protection through preset undervoltage and overvoltage thresholds.

[0004] However, existing traditional sampling protection circuits are generally unipolar, which cannot meet the requirements of positive and negative sampling protection. At the same time, they cannot meet the different adaptation scenarios of the protection circuit and cannot adapt to different over- and under-voltage threshold points. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a voltage protection circuit that can sample positive and negative power supplies. It is suitable for overvoltage and undervoltage protection of high-voltage pulse modulators. It achieves overvoltage and undervoltage monitoring and identification protection by sampling the voltage of each solid-state switching unit in the solid-state pulse modulator, and can be compatible with positive and negative values ​​of the sampled voltage for fault monitoring and protection.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A voltage protection circuit capable of sampling positive and negative power supplies includes a voltage sampling circuit, a sampling voltage conversion and amplification circuit, a comparison circuit, and a fault indication and protection circuit.

[0008] The voltage sampling circuit is used to acquire the voltage signal of the high voltage pulse modulator protection sampling point, and its output is connected to the sampling voltage conversion and discharge circuit.

[0009] The sampling voltage conversion and amplification circuit is used to amplify the sampled voltage and send it to the comparison circuit, or to convert the sampled negative voltage into a positive voltage, amplify it, and then send it to the comparison circuit.

[0010] The comparison circuit compares the received voltage with a threshold and outputs a voltage fault signal to the fault indication and protection circuit based on the comparison result.

[0011] The fault indication and protection circuit is used to issue fault indication information and fault protection signals.

[0012] The sampling voltage conversion and amplification circuit includes a voltage follower circuit, an inverting proportional operational amplifier, and a DIP switch. The output of the voltage sampling circuit is connected to the voltage follower circuit. The output of the voltage follower circuit is connected to the input of the inverting proportional operational amplifier and the DIP switch S1. The inverting proportional operational amplifier is used to amplify the output voltage of the voltage follower circuit in an inverting proportional manner. The output of the inverting proportional operational amplifier is connected to the DIP switch S1. The DIP switch S1 is used to select whether the output of the voltage follower circuit or the output of the inverting proportional operational amplifier is connected to the comparator circuit.

[0013] The voltage sampling circuit includes resistors R1, R2, R3, and R4, and capacitors C3 and C5;

[0014] The sampling terminal HV-IN is used to set the sampling point of the high-voltage pulse modulator to collect the sampling voltage; the sampling terminal HV-IN is grounded after being connected in series with resistors R1, R2, and R3; a terminal is led out between resistors R2 and R3 and led out through resistor R4 to the output terminal of the voltage sampling circuit, which is used to connect to the sampling voltage conversion and amplification circuit; a capacitor C3 is connected in parallel across resistor R3, and the output terminal of the voltage sampling circuit is grounded through capacitor C5.

[0015] The output of the voltage sampling circuit is connected to the sampling voltage conversion and amplification circuit via resistor R5.

[0016] The comparison circuit includes an undervoltage fault comparison circuit and an overvoltage fault comparison circuit. The output terminals of the sampling voltage conversion and amplification circuit are respectively connected to the undervoltage fault comparison circuit and the overvoltage fault comparison circuit. The undervoltage fault comparison circuit and the overvoltage fault comparison circuit output the undervoltage and overvoltage comparison results and send them to the fault indication and protection circuit.

[0017] The undervoltage fault comparison circuit includes a voltage comparator N3A. The output of the sampling voltage conversion and amplification circuit is connected to the inverting input of the voltage comparator N3A via a resistor R11. The non-inverting input of the voltage comparator N3A is connected to one end of a resistor R10 and one end of an adjustable resistor RP1, with the other end of the adjustable resistor RP1 grounded. The other end of a resistor R10 is connected to the positive terminal of the power supply. The output of the voltage comparator N3A is connected to the fault indication and protection circuit.

[0018] The overvoltage fault comparison circuit includes a voltage comparator N3B.

[0019] The output of the sampling voltage conversion and amplification circuit is connected to the non-inverting input of voltage comparator N3B via resistor R13; the inverting input of voltage comparator N3B is connected to one end of resistor R14 and one end of adjustable resistor RP2, with the other end of adjustable resistor RP2 grounded; the other end of resistor R14 is connected to the positive terminal of the power supply; the output of voltage comparator N3B is connected to the fault indication and protection circuit.

[0020] The fault indication and protection circuit includes an undervoltage fault branch and an overvoltage fault branch, which are used to indicate undervoltage faults and overvoltage faults, respectively.

[0021] Both the overvoltage fault branch and the undervoltage fault branch include an optocoupler. The output signal of the comparator is used to control the conduction state of the primary side of the optocoupler. The first terminal of the secondary side of the optocoupler is connected to the cathode of the diode, and the second terminal of the secondary side of the optocoupler is connected to the anode of the diode. The anode of the diode leads out an undervoltage or overvoltage fault signal terminal to output a fault signal characterizing overvoltage or undervoltage.

[0022] The host computer's sampling port is connected to the undervoltage or overvoltage fault signal terminal to read its voltage signal. The host computer then determines the current undervoltage or overvoltage fault state based on the read voltage signal.

[0023] The advantages of this invention are: to adapt to charging power supplies of different polarities, the sampling protection circuit adopts a bipolar sampling method and has both undervoltage and overvoltage detection protection circuits. The protection threshold can also be adjusted according to usage requirements, resulting in a wider range of applications and more comprehensive protection. The protection circuit also includes:

[0024] 1. The circuit is simple in design. The S1 DIP switch makes this sampling circuit suitable for both positive and negative voltage sampling, greatly reducing costs and broadening its applicability. 2. The sliding rheostats RP1 and RP2 allow for adjustable undervoltage and overvoltage thresholds, making it suitable for sampling protection at different power levels and charging voltages. The circuit is also easy and flexible to adjust, offering wider applicability. 3. The output is optocoupler-isolated, resulting in better signal transmission isolation, enhanced safety, and more accurate fault diagnosis. Attached Figure Description

[0025] The following is a brief explanation of the contents of each of the accompanying drawings and the markings in the drawings:

[0026] Figure 1 This is a schematic diagram of the protection circuit of the present invention. Detailed Implementation

[0027] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and the description of the preferred embodiments.

[0028] This embodiment addresses the issue that traditional sampling protection circuits are generally unipolar. To adapt to charging power supplies of different polarities, the sampling protection circuit adopts a bipolar sampling method and features both undervoltage and overvoltage detection protection circuits. The protection threshold can also be adjusted according to usage requirements, resulting in a wider range of applications and more comprehensive protection.

[0029] This embodiment of a voltage protection circuit capable of sampling positive and negative power supplies includes a voltage sampling circuit, a sampling voltage conversion and amplification circuit, a comparison circuit, and a fault indication and protection circuit.

[0030] The voltage sampling circuit is used to acquire the voltage signal of the high-voltage pulse modulator protection sampling point, and its output is connected to the sampling voltage conversion and discharge circuit. The sampling voltage conversion and amplification circuit is used to amplify the sampled voltage and send it to the comparison circuit, or to convert the sampled negative voltage into a positive voltage and then amplify it before sending it to the comparison circuit. The comparison circuit compares the received voltage with the threshold and outputs a voltage fault signal to the fault indication and protection circuit according to the comparison result. The fault indication and protection circuit is used to issue fault indication information and fault protection signals.

[0031] In this embodiment, the sampling voltage conversion and amplification circuit includes a voltage follower circuit, an inverting proportional operational amplifier, and a DIP switch. The output terminal of the voltage sampling circuit is connected to the voltage follower circuit. The output terminal of the voltage follower circuit is connected to the input terminal of the inverting proportional operational amplifier and the DIP switch S1. The inverting proportional operational amplifier is used to amplify the output voltage of the voltage follower circuit in an inverting proportional manner. The output terminal of the inverting proportional operational amplifier is connected to the DIP switch S1. The DIP switch S1 is used to select whether the output terminal of the voltage follower circuit or the output terminal of the inverting proportional operational amplifier is connected to the comparator circuit.

[0032] The voltage sampling circuit includes resistors R1, R2, R3, and R4, and capacitors C3 and C5. The sampling terminal HV-IN is used to set the sampling point of the high-voltage pulse modulator to acquire the sampling voltage. The sampling terminal HV-IN is grounded after passing through resistors R1, R2, and R3 in series. A terminal is led out between resistors R2 and R3 and then through resistor R4 to lead out the output terminal of the voltage sampling circuit, which is used to connect to the sampling voltage conversion and amplification circuit. A capacitor C3 is connected in parallel across resistor R3, and the output terminal of the voltage sampling circuit is grounded through capacitor C5.

[0033] The output of the voltage sampling circuit is connected to the sampling voltage conversion and amplification circuit via resistor R5. The comparison circuit includes an undervoltage fault comparison circuit and an overvoltage fault comparison circuit. The output of the sampling voltage conversion and amplification circuit is connected to the undervoltage fault comparison circuit and the overvoltage fault comparison circuit, respectively. The undervoltage fault comparison circuit and the overvoltage fault comparison circuit output the undervoltage and overvoltage comparison results and send them to the fault indication and protection circuit.

[0034] The undervoltage fault comparison circuit includes a voltage comparator N3A. The output of the sampling voltage conversion and amplification circuit is connected to the inverting input of the voltage comparator N3A via a resistor R11. The non-inverting input of the voltage comparator N3A is connected to one end of a resistor R10 and one end of an adjustable resistor RP1, with the other end of the adjustable resistor RP1 grounded. The other end of a resistor R10 is connected to the positive terminal of the power supply. The output of the voltage comparator N3A is connected to the fault indication and protection circuit.

[0035] The overvoltage fault comparison circuit includes a voltage comparator N3B. The output of the sampling voltage conversion and amplification circuit is connected to the non-inverting input of the voltage comparator N3B via resistor R13. The inverting input of the voltage comparator N3B is connected to one end of resistor R14 and one end of adjustable resistor RP2, with the other end of adjustable resistor RP2 grounded. The other end of resistor R14 is connected to the positive terminal of the power supply. The output of the voltage comparator N3B is connected to the fault indication and protection circuit.

[0036] The fault indication and protection circuit includes an undervoltage fault branch and an overvoltage fault branch, used to indicate undervoltage and overvoltage faults respectively. Both the overvoltage and undervoltage fault branches include optocouplers. The comparator's output signal is used to detect the conduction state of the primary side of the optocoupler. The first terminal of the optocoupler's secondary side is connected to the cathode of a diode, and the second terminal of the optocoupler's secondary side is connected to the anode of the diode. The anode of the diode outputs an undervoltage or overvoltage fault signal terminal to indicate the fault signal representing overvoltage or undervoltage.

[0037] The host computer's sampling port is connected to the undervoltage or overvoltage fault signal terminal to read its voltage signal. The host computer then determines the current undervoltage or overvoltage fault state based on the read voltage signal. Figure 1As shown, the present invention provides a voltage protection circuit capable of sampling positive and negative power supplies, including a voltage sampling circuit 1, a sampling voltage amplification circuit 2, sampling voltage and threshold voltage comparison circuits 3 and 4, and fault indication circuits 5 and 6.

[0038] Specifically, such as Figure 1 As shown in label 1, the voltage at the HV-IN terminal can be either positive or negative. R1, R2, and R3 form a voltage sampling circuit, using the voltage across the low-side resistor R3 as the input voltage. Generally, R1 and R2 can be megaohm-level resistors, and R3 a kiloohm-level resistor. The resistor values ​​can be flexibly adjusted according to the input voltage to ensure the sampled input voltage is within ±10V. When HV-IN is positive, the voltage at resistor R5 is positive; when HV-IN is negative, the voltage at resistor R5 is negative. R5 is the input resistor of the voltage follower circuit, primarily used to eliminate the influence of bias current on the output voltage and for current limiting. N1 in label 2 is a rail-to-rail input / output, low offset voltage precision operational amplifier, containing two op-amps. N1A forms a voltage follower circuit, meaning that the output voltage at pin 1 of N1 is consistent with the input voltage at pin 3 of N1, serving to isolate, buffer, and increase output stability. N1B forms an inverting proportional operational amplifier circuit, where the output voltage at pin 7 of N1 is proportional to the input voltage at pin 6. The ratio is determined by the ratio of resistors R8 and R6. Since it is an inverting proportional amplifier circuit, the output voltage at pin 7 of N1 is inversely related to the input voltage at pin 6. If HV-IN is a positive voltage, pin 3 of N1 is also positive. After passing through the N1A circuit, pin 1 of N1 also outputs a positive voltage. At this time, switching switch S1 to position 1-2 disables the N1B circuit, and pin 7 output is no longer needed, thus ensuring that the voltage at point M is positive, allowing the subsequent circuit system to start working. If HV-IN is a negative voltage, pin 3 of N1 is also negative. After passing through the N1A circuit, pin 1 of N1 also outputs a negative voltage, and pin 7 output becomes positive. Switching switch S1 to position 2-3 ensures that the voltage at point M is positive, allowing the subsequent circuit system to start working. In this way, by selecting the position of switch S1, positive and negative voltages can be sampled.

[0039] Upon reaching point M, the current splits into two branches. N3 is an open-drain output dual-channel voltage comparator with good temperature stability and low input offset voltage. Branch 1, i.e., the circuit marked 3, constitutes an inverting voltage comparator. The voltage at pin 3 of N3 is a fixed value, which can be adjusted by the sliding rheostat RP1. By comparing the voltages at pins 2 and 3 of N3, the voltage at pin 1 of N3 can be determined. For example, if the voltage at pin 3 of N3 is adjusted to a fixed value of 5V by adjusting RP1, when the sampled voltage at pin 2 is less than 5V, the output voltage at pin 1 of N3 should always be 12V; when the sampled voltage at pin 2 is higher than 5V, the output voltage at pin 1 of N3 will be 0V. Similarly, branch 4, i.e., the circuit marked 4, constitutes a non-inverting voltage comparator. The voltage at pin 6 of N3 is a fixed value, which can be adjusted by the sliding rheostat RP2. By comparing the voltages at pins 5 and 6 of N3, the output voltage at pin 7 of N3 can be determined. If the voltage at pin 6 of N3 is adjusted to a fixed value of 10V by adjusting RP2, when the sampling voltage at pin 5 is less than 10V, the voltage output at pin 7 of N3 should always be 0V; when the sampling voltage at pin 5 is higher than 10V, the output voltage at pin 7 of N3 will be 12V.

[0040] Figure 1Points 5 and 6 in the diagram are fault identification circuits, which use optocoupler isolation output. When the voltage at point N is 12V, there is no input current to the primary winding of optocoupler N2, and the secondary winding cannot conduct, so there is no voltage output at the positive terminal of V1. When the voltage at point N is 0V, there is input current to the primary winding of optocoupler N2, and the secondary winding conducts, so there is a high-level output at the positive terminal of V1. The positive terminal signal of V1 can be connected to the I / O input point of a microcontroller or PLC, defined as an undervoltage fault point. By judging whether the voltage at this point is high or low, it can be determined whether it is an undervoltage fault. The overall logic is as follows: When the HV-IN voltage continuously decreases due to a fault, the voltage at point M also continuously decreases. When the voltage at point M falls below the threshold voltage set at pin 3 of N3, the output at point N changes from low to high. At this time, the secondary winding of the optocoupler switches from the conducting state to the non-conducting state, and the positive terminal voltage of V1 switches from high to low. Assuming that the I / O input program logic of the microcontroller or PLC is high when there is no fault, then an undervoltage fault should be identified. Similarly, when the voltage at point P is 12V, there is no input current in the primary winding of optocoupler N4, so the secondary winding of the optocoupler cannot conduct, and there is no voltage output at the positive terminal of V2. When the voltage at point P is 0V, there is input current in the primary winding of optocoupler N4, so the secondary winding of the optocoupler conducts, and there is a high-level output at the positive terminal of V2. The positive terminal signal of V2 can be connected to the I / O input point of the microcontroller or PLC and defined as an overvoltage fault point. By judging whether the voltage at this point is high or low, it can be determined whether it is an overvoltage fault. The overall logic is as follows: When the HV-IN voltage continuously rises due to a fault, the voltage at point M continuously rises. When the voltage at point M exceeds the threshold voltage set at pin 6 of N3, the output at point P changes from low to high. At this time, the secondary side of the optocoupler switches from the conducting state to the non-conducting state, and the positive terminal voltage of V2 switches from high to low. Assuming that the I / O input program logic of the microcontroller or PLC is high when it is a fault-free state, then an overvoltage fault state should be identified at this time.

[0041] This invention, through the design of DIP switch S1, meets the requirement of sampling both positive and negative power supplies. By designing two positive and negative voltage comparison circuits, it achieves the identification of undervoltage and overvoltage faults. Furthermore, through the design of sliding rheostats RP1 and RP2, the undervoltage and overvoltage threshold points are adjustable to adapt to different threshold protection requirements. Finally, through optocoupler isolation output, it achieves accurate identification of undervoltage and overvoltage faults, thereby identifying the charging voltage status and quickly protecting against fault conditions.

[0042] Obviously, the specific implementation of this invention is not limited to the above-described methods. Any non-substantial improvements made using the inventive concept and technical solution of this invention are within the protection scope of this invention.

Claims

1. A voltage protection circuit that can sample positive and negative power supplies, characterized by: The voltage sampling circuit, the sampling voltage conversion and amplification circuit, the comparison circuit, and the fault indication and protection circuit are included. The voltage sampling circuit is used to collect the voltage signal of the high-voltage pulse modulator protection sampling point, and the output end is connected to the sampling voltage conversion and discharge circuit. The sampling voltage conversion and amplification circuit is used to amplify the sampled voltage and send it into the comparison circuit or convert the negative voltage into positive voltage and then amplify and send it into the comparison circuit. The comparison circuit compares the received voltage with the threshold value and outputs the voltage fault signal to the fault indication and protection circuit according to the comparison result. The fault indication and protection circuit is used to issue the fault indication information and the fault protection signal.

2. The voltage protection circuit capable of sampling positive and negative power supply according to claim 1, characterized in that: The sampling voltage conversion and amplification circuit includes a voltage follower circuit, an inverting proportional operational amplifier, and a dial switch, the output end of the voltage sampling circuit is connected to the voltage follower circuit, the output end of the voltage follower circuit is connected to the input end of the inverting proportional operational amplifier and the dial switch S1 respectively, the inverting proportional operational amplifier is used to inversely and proportionally amplify the output voltage of the voltage follower circuit, the output end of the inverting proportional operational amplifier is connected to the dial switch S1, and the output end of the voltage follower circuit or the output end of the inverting proportional operational amplifier is selected by the dial switch S1 and connected to the comparison circuit.

3. A voltage protection circuit for positive and negative supply sampling as claimed in claim 1 or 2, characterized in that: The voltage sampling circuit includes resistors R1, R2, R3, R4 and capacitors C3, C5. The sampling terminal HV-IN is used to be arranged at the high-voltage pulse modulator protection sampling point to collect the sampling voltage, the sampling terminal HV-IN is connected to the ground through the resistors R1, R2, and R3 in series, the terminal between the resistors R2 and R3 is connected to the output end of the voltage sampling circuit through the resistor R4 to be connected to the sampling voltage conversion and amplification circuit, and the capacitors C3 are arranged in parallel at both ends of the resistor R3, and the output end of the voltage sampling circuit is connected to the ground through the capacitor C5.

4. A voltage protection circuit capable of positive and negative power supply sampling as claimed in claim 1 or 2, characterized in that: The output end of the voltage sampling circuit is connected to the sampling voltage conversion and amplification circuit through the resistor R5.

5. A voltage protection circuit capable of positive and negative power supply sampling as claimed in claim 1 or 2, characterized in that: The comparison circuit includes an under-voltage fault comparison circuit and an over-voltage fault comparison circuit, the output end of the sampling voltage conversion and amplification circuit is connected to the under-voltage fault comparison circuit and the over-voltage fault comparison circuit respectively, and the under-voltage fault comparison circuit and the over-voltage fault comparison circuit output the under-voltage and over-voltage comparison results and send them to the fault indication and protection circuit.

6. A voltage protection circuit for positive and negative supply sampling as claimed in claim 5, characterized in that: The under-voltage fault comparison circuit includes a voltage comparator N3A, the output end of the sampling voltage conversion and amplification circuit is connected to the inverting input end of the voltage comparator N3A through the resistor R11, the non-inverting input end of the voltage comparator N3A is connected to one end of the resistor R10 and one end of the adjustable resistor RP1 respectively, the other end of the adjustable resistor RP1 is connected to the ground, the other end of the resistor R10 is connected to the positive electrode of the power supply, and the output end of the voltage comparator N3A is connected to the fault indication and protection circuit.

7. A voltage protection circuit for positive and negative power supply sampling as defined in claim 5, characterized by: The over-voltage fault comparison circuit includes a voltage comparator N3B, An output end of the sampling voltage conversion and amplification circuit is connected to a non-inverting input end of a voltage comparator N3B through a resistor R13; an inverting input end of the voltage comparator N3B is connected to one end of a resistor R14 and one end of an adjustable resistor RP2, and the other end of the adjustable resistor RP2 is grounded; the other end of the resistor R14 is connected to a positive electrode of a power supply; and an output end of the voltage comparator N3B is connected to the fault indication and protection circuit.

8. A voltage protection circuit capable of positive and negative power supply sampling as claimed in claim 1 or 2, characterized in that: The fault indication and protection circuit comprises an under-voltage fault branch and an over-voltage fault branch for respectively indicating an under-voltage fault and an over-voltage fault.

9. A voltage protection circuit for positive and negative power supply sampling as claimed in claim 1 or 2, characterized in that: The over-voltage fault branch and the under-voltage fault branch each comprise an optocoupler, and an output signal of a comparator is used to control a conduction state of a primary side of the optocoupler; a first terminal of a secondary side of the optocoupler is connected to a cathode of a diode, a second terminal of the secondary side of the optocoupler is connected to an anode of the diode, and the anode of the diode leads out an under-voltage or over-voltage fault signal terminal for outputting a fault signal representing over-voltage or under-voltage.

10. A voltage protection circuit for positive and negative supply sampling as claimed in claim 9, characterized in that: A sampling port of the upper computer is connected to the under-voltage or over-voltage fault signal terminal to read a voltage signal thereof, and the upper computer judges a current under-voltage or over-voltage fault state according to the read voltage signal.

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