A MCU crash protection device based on dynamic voltage restorer

Abstract

The present invention provides an MCU crash protection device based on a dynamic voltage restorer. The dynamic voltage restorer device can ensure that the thyristor continues to be turned on when the MCU crashes, thereby achieving timely protection and ensuring that the load equipment can operate stably and safely. The device is connected in series between a system power supply and a load, and includes connected thyristors and an inverter module. The inverter module includes an MCU, and the inverter module also includes a conversion unit and a fault protection unit. The MCU, the conversion unit, the fault protection unit, and the thyristor are connected in series in sequence. The conversion unit determines the MCU state based on a signal sent by the MCU, thereby performing inverter output level conversion on the circuit. The fault protection unit provides a drive signal to the thyristor based on the level output of the conversion unit, thereby achieving MCU crash protection.

Description

Technical Field

[0001] The present invention relates to the technical field of power quality management, in particular to a dynamic voltage restorer technology, and specifically to an MCU crash protection device based on a dynamic voltage restorer. Background Art

[0002] The dynamic voltage restorer (DVR) is a series compensation device with an energy storage device. It is connected in series between sensitive loads and the system power supply to prevent system voltage interference from causing abnormal operation of sensitive loads. When the system voltage is disturbed and a voltage sag occurs, the dynamic voltage regulator compensates for the dropped voltage within 2mS, so that the load side voltage does not feel the disturbance, ensuring the safe and reliable operation of sensitive loads.

[0003] When there is no power drop in the current dynamic voltage restorer on the market, the MCU in the dynamic voltage restorer will send a drive signal to keep the thyristor connected in series between the power supply and the load on to ensure stable operation of the equipment. However, if the MCU crashes at this time, it is very likely that the thyristor drive signal will be lost, the equipment will stop working, and cause significant losses. To this end, there are currently two main solutions to dynamic voltage restorer failures. One is manual bypass, that is, bypassing the dynamic voltage restorer through a manual bypass switch to ensure normal operation of the load and put it into use again after the device is repaired; the other is inverter module power-off protection, but these two methods still have the following defects:

[0004] (1) Disadvantages of manual bypass: DVR is online and maintenance-free. Manual bypass is a remedial measure after a fault occurs and cannot provide timely and effective protection.

[0005] (2) Disadvantages of inverter module power-off protection: This method means that when the inverter module loses power, the thyristor will continue to conduct to ensure the operation of the load equipment. However, if the inverter module is not powered off, the MCU freezes and causes the drive signal of the thyristor to be lost, and this solution will not work. Summary of the Invention

[0006] In response to the above problems, the present invention provides an MCU crash protection device based on a dynamic voltage restorer, which can enable the dynamic voltage restorer device to continue to keep the thyristor turned on when the MCU crashes, thereby achieving timely protection and ensuring that the load equipment can operate stably and safely.

[0007] The technical solution is as follows: an MCU crash protection device based on a dynamic voltage restorer is connected in series between a system power supply and a load, and includes a thyristor and an inverter module connected thereto. The inverter module includes an MCU, and is characterized in that the inverter module further includes a conversion unit and a fault protection unit. The MCU, conversion unit, fault protection unit, and thyristor are sequentially connected in series.

[0008] The conversion unit determines the state of the MCU according to the signal sent by the MCU, thereby performing inverter output level conversion on the circuit;

[0009] The fault protection unit provides a driving signal to the thyristor according to the level output of the conversion unit, thereby realizing MCU crash protection.

[0010] It is further characterized by:

[0011] The conversion unit includes resistors R1 to R10, a capacitor C1, diodes D1 and D2, a voltage follower U1, comparators U2 and U3, and a NAND gate U4; the positive input end of the voltage follower U1 is connected to the signal pin end of the MCU, the negative input end of the voltage follower U1 is connected to the output end of the voltage follower U1 and to one end of the resistor R1, the other end of the resistor R1 is connected to one end of the capacitor C1, one end of the resistors R2 and R5, the positive input end of the comparator U2, and the negative input end of the comparator U3, the other end of the capacitor C1 and the resistor R2 are connected and then grounded, the negative input end of the comparator U2 is connected to one end of the resistors R3 and R4, the other end of the resistor R3 is connected to the power supply 3.3V, and the negative input end of the resistor R4 is connected to the positive input end of the comparator U2. The other end is grounded, the positive input end of the comparator U3 is connected to one end of the resistors R6, R7, and R8, the other end of the resistor R7 is connected to a power supply of 3.3V, the other end of the resistor R6 is grounded, the other end of the resistor R8 is connected to the positive electrode of the diode D2, the negative electrode of the diode D2 is connected to one end of the resistor R9, the output end of the comparator U3, and the first input end of the NAND gate U4, the other end of the resistor R9 is connected to a power supply of 5V, the other end of the resistor R5 is connected to the positive electrode of the diode D1, the negative electrode of the diode D1 is connected to one end of the resistor R10, the output end of the comparator U2, and the second input end of the NAND gate U4, the other end of the resistor R10 is connected to a power supply of 5V, and the output end of the NAND gate U4 is connected to the fault protection unit;

[0012] The fault protection unit includes resistors R11 to R16, a transistor Q1, an optocoupler U5, and capacitors C2 to C4. The optocoupler U5 adopts a model HCPL2631 dual-channel high-speed isolation optocoupler; one end of the resistor R11 is connected to the output end of the NAND gate U4, the other end of the resistor R11 is connected to one end of the resistor R12 and the base of the transistor Q1, the other end of the resistor R12 is connected to the emitter of the transistor Q1 and then to the power supply 3.3V, the collector of the transistor Q1 is connected to the 4th pin of the optocoupler U5 through the resistor R13, and the 1st pin of the optocoupler U5 is connected to the resistor R13. One end of R14, the other end of the resistor R14 is connected to pins 2 and 3 of the photoelectric coupler U5 and then grounded, pin 5 of the photoelectric coupler U5 is connected to one end of the capacitors C2, C3, and C4 and then grounded, pin 8 of the photoelectric coupler U5 is connected to one end of the resistors R15 and R16 and the other end of the capacitor C2 and then connected to the power supply 5V, pin 7 of the photoelectric coupler U5 is connected to the other end of the capacitor C3 and the other end of the resistor R15; pin 6 of the photoelectric coupler U5 is connected to the other end of the capacitor C4 and the other end of the resistor R16, and this connection point is connected to the thyristor as a fault protection signal end;

[0013] The signal sent by the signal pin end of the MCU is a square wave signal with a frequency of 8KHz and a duty cycle of 50%.

[0014] The beneficial effect of the present invention is that after receiving the signal sent by the MCU, the conversion unit determines the MCU state, thereby performing inverter output level conversion on the circuit, and then the fault protection unit provides a drive signal to the thyristor according to the level output of the conversion unit, thereby realizing MCU crash protection, which can ensure that when the MCU crashes, timely and effective protection is achieved, and the response speed is fast, thereby ensuring that the load equipment can operate stably and safely. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural block diagram of the present invention;

[0016] Figure 2 This is a circuit diagram of the conversion unit in the present invention;

[0017] Figure 3 This is a circuit diagram of the fault protection unit in the present invention;

[0018] Figure 4 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0019] like Figures 1 to 4As shown, the present invention provides an MCU crash protection device based on a dynamic voltage restorer, which is connected in series between a system power supply 1 and a load 2, and includes a connected thyristor SCR and an inverter module. The inverter module includes an MCU, and the thyristor SCR is connected to the load 2. The inverter module also includes a conversion unit 3 and a fault protection unit 4. The MCU, the conversion unit 3, the fault protection unit 4, and the thyristor SCR are connected in series in sequence; wherein the conversion unit 3 determines the MCU state according to the signal sent by the MCU, thereby performing inverter output level conversion on the circuit; the fault protection unit 4 provides a drive signal to the thyristor SCR according to the level output of the conversion unit 3, thereby realizing MCU crash protection.

[0020] The conversion unit 3 includes resistors R1 to R10, a capacitor C1, diodes D1 and D2, a voltage follower U1, comparators U2 and U3, and a NAND gate U4; the positive input terminal of the voltage follower U1 is connected to the signal pin terminal of the MCU, and the signal emitted by the signal pin terminal of the MCU is a square wave signal with a frequency of 8KHz and a duty cycle of 50%. The negative input terminal of the voltage follower U1 is connected to the output terminal of the voltage follower U1 and is connected to one end of the resistor R1. The other end of the resistor R1 is connected to one end of the capacitor C1, one end of the resistors R2 and R5, the positive input terminal of the comparator U2, and the negative input terminal of the comparator U3. The other ends of the capacitor C1 and the resistor R2 are connected and then grounded. The negative input terminal of the comparator U2 is connected to one end of the resistors R3 and R4. The resistor R 3 is connected to a power supply of 3.3V, the other end of the resistor R4 is grounded, the positive input terminal of the comparator U3 is connected to one end of the resistors R6, R7, and R8, the other end of the resistor R7 is connected to the power supply of 3.3V, the other end of the resistor R6 is grounded, the other end of the resistor R8 is connected to the anode of the diode D2, the cathode of the diode D2 is connected to one end of the resistor R9, the output end of the comparator U3, and the first input end of the NAND gate U4, the other end of the resistor R9 is connected to a power supply of 5V, the other end of the resistor R5 is connected to the anode of the diode D1, the cathode of the diode D1 is connected to one end of the resistor R10, the output end of the comparator U2, and the second input end of the NAND gate U4, the other end of the resistor R10 is connected to the power supply of 5V, and the output end of the NAND gate U4 is connected to the fault protection unit 4.

[0021] Fault protection unit 4 includes resistors R11 to R16, transistor Q1, photocoupler U5, and capacitors C2 to C4. Photocoupler U5 adopts model HCPL2631 dual-channel high-speed isolation optocoupler; one end of resistor R11 is connected to the output end of NAND gate U4, the other end of resistor R11 is connected to one end of resistor R12 and the base of transistor Q1, the other end of resistor R12 is connected to the emitter of transistor Q1 and then to the power supply 3.3V, the collector of transistor Q1 is connected to pin 4 of photocoupler U5 through resistor R13, and pin 1 of photocoupler U5 is connected to the One end, the other end of the resistor R14 is connected to the 2nd and 3rd pins of the photoelectric coupler U5 and then to ground, the 5th pin of the photoelectric coupler U5 is connected to one end of the capacitors C2, C3, and C4 and then to ground, the 8th pin of the photoelectric coupler U5 is connected to one end of the resistors R15 and R16 and the other end of the capacitor C2 and then to the power supply 5V, the 7th pin of the photoelectric coupler U5 is connected to the other end of the capacitor C3 and the other end of the resistor R15; the 6th pin of the photoelectric coupler U5 is connected to the other end of the capacitor C4 and the other end of the resistor R16, and this connection point is connected to the thyristor SCR as the fault protection signal end.

[0022] The working principle of the present invention is as follows: the SCR_LIVE signal sent by the MCU is a square wave signal with a frequency of 8KHz and a duty cycle of 50% (high level 3.3V, low level 0V), which is then low-pass filtered: that is, after passing through the voltage follower U1, it passes through a first-order RC low-pass filter composed of a resistor R1 and a capacitor C1. The cutoff frequency of this filter is f = 1 / (2πRC) = 31.9Hz, so after passing through the low-pass filter, the square wave is converted into a DC voltage with an amplitude of approximately 1.65V (DC bias voltage); then a voltage comparison is performed: the converted DC voltage is compared with the negative input terminal voltage of the comparator U2 and the positive input terminal voltage of the comparator U3 respectively (here, the level of the comparator U2 is the voltage on the resistor R4. After the resistors R3 and R4 divide the power supply 3.3V, a voltage value of 0.97V is calculated by the existing algorithm, which is the low voltage level; similarly, the level of the comparator U3 is determined by the resistors R6 and R7. 7. The power supply 3.3V is divided, and the voltage level after division is calculated by the existing algorithm to be 1.89V, which is a high voltage level; if the voltage after passing through the low-pass filter is within the range of 0.97V to 1.89V, it is considered that the MCU is in a non-frozen state). If the DC voltage is less than 0.97V or greater than 1.89V, it will be determined that the MCU is frozen, and the NAND gate outputs a high level; otherwise, when the MCU is not frozen, the NAND gate outputs a low level; when the MCU is frozen, the signal receiving end SCR_ALIVE signal on the fault protection unit 4 changes from low level to high level, the transistor Q1 changes from on state to off state, the optocoupler U5 changes from on state to off state, and the secondary side output SCR_LIVE_SELV signal of the optocoupler U5 changes from low level to high level. This signal is used as a fault protection signal to drive the thyristor SCR to turn on, thereby realizing timely protection against MCU freeze.

[0023] In summary, through the MCU crash protection device based on the dynamic voltage restorer of the present invention, when the MCU crashes, no matter whether the MCU pin is set high or low, the protection device can provide timely and effective protection with high reliability; at the same time, the protection device is an online detection device, and the delay from the MCU crash to the thyristor SCR opening is within 2 milliseconds, and the response protection speed is fast; in addition, the protection device converts the MCU crash into high and low level outputs, and the conversion process can be extended to lines with similar functions, with good flexibility and variability.

[0024] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0025] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. An MCU crash protection device based on a dynamic voltage restorer, connected in series between a system power supply and a load, comprising a thyristor and an inverter module connected thereto, wherein the inverter module includes an MCU, and characterized in that: The inverter module further includes a conversion unit and a fault protection unit, wherein the MCU, the conversion unit, the fault protection unit and the thyristor are sequentially connected in series; The conversion unit determines the state of the MCU according to the signal sent by the MCU, thereby performing inverter output level conversion on the circuit; The fault protection unit provides a driving signal to the thyristor according to the level output of the conversion unit, thereby realizing MCU crash protection; the conversion unit includes resistors R1~R10, capacitor C1, diodes D1, D2, voltage follower U1, comparators U2, U3, and NAND gate U4; the positive input end of the voltage follower U1 is connected to the signal pin end of the MCU, the negative input end of the voltage follower U1 is connected to the output end of the voltage follower U1 and to one end of the resistor R1, and the other end of the resistor R1 is connected to the One end of the capacitor C1, one end of the resistors R2 and R5, the positive input end of the comparator U2, and the negative input end of the comparator U3 are all connected. The other ends of the capacitor C1 and the resistor R2 are connected and then grounded. The negative input end of the comparator U2 is connected to one end of the resistors R3 and R4. The other end of the resistor R3 is connected to a power supply of 3.3V. The other end of the resistor R4 is grounded. The positive input end of the comparator U3 is connected to one end of the resistors R6, R7, and R8. The other end of the resistor R7 is connected to a power supply of 3.3V. The other end of the resistor R6 is grounded, the other end of the resistor R8 is connected to the anode of the diode D2, the cathode of the diode D2 is connected to one end of the resistor R9, the output end of the comparator U3, and the first input end of the NAND gate U4, the other end of the resistor R9 is connected to a power supply of 5V, the other end of the resistor R5 is connected to the anode of the diode D1, the cathode of the diode D1 is connected to one end of the resistor R10, the output end of the comparator U2, and the second input end of the NAND gate U4, and the other end of the resistor R10 is connected to a power supply of 5V. The output of NAND gate U4 is connected to the fault protection unit; the fault protection unit includes resistors R11-R16, transistor Q1, optocoupler U5, and capacitors C2-C4. Optocoupler U5 is a HCPL2631 dual-channel high-speed isolation optocoupler. One end of resistor R11 is connected to the output of NAND gate U4. The other end of resistor R11 is connected to one end of resistor R12 and the base of transistor Q1. The other end of resistor R12 is connected to the emitter of transistor Q1 and then to power supply 3.3V, the collector of the transistor Q1 is connected to pin 4 of the photoelectric coupler U5 through the resistor R13, pin 1 of the photoelectric coupler U5 is connected to one end of the resistor R14, the other end of the resistor R14 is connected to pins 2 and 3 of the photoelectric coupler U5 and then to ground, pin 5 of the photoelectric coupler U5 is connected to one end of the capacitors C2, C3, and C4 and then to ground, pin 8 of the photoelectric coupler U5 is connected to one end of the resistors R15 and R16 and the other end of the capacitor C2 and then to the 5V power supply, pin 7 of the photoelectric coupler U5 is connected to the other end of the capacitor C3 and the other end of the resistor R15; pin 6 of the photoelectric coupler U5 is connected to the other end of the capacitor C4 and the other end of the resistor R16, and this connection point is connected to the thyristor as a fault protection signal end.

2. The MCU crash protection device based on a dynamic voltage restorer according to claim 1, characterized in that: The signal sent by the signal pin end of the MCU is a square wave signal with a frequency of 8KHz and a duty cycle of 50%.

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