Overvoltage and overcurrent mutation protection circuit and method

Abstract

One technical solution of the present invention is to provide a protection circuit against voltage and current mutations, which is characterized by including an input control unit, a DC voltage stabilization unit, a high voltage detection unit, a voltage conversion and power supply unit, a voltage mutation detection unit, a charging and voltage mutation current limiting unit, a voltage charging completion detection unit, and a fast turn-off circuit. The present invention also provides a working method for the protection circuit against voltage and current mutations. The protection circuit against voltage and current mutations provided by the present invention can well complete the suppression of overvoltage and overcurrent during the startup of the auxiliary power supply circuit, suppress the mutation of the power supply voltage after normal operation, take effective protection against the overhigh auxiliary power supply voltage, and well protect the auxiliary power supply circuit from damage when the power supply voltage mutates or is too high. The structure of the present invention is simple and easy to implement, and it can be applied not only in single-phase AC power supply, but also in three-phase AC power supply, DC power supply or AC-DC hybrid power supply.

Description

Technical Field

[0001] The present invention relates to an inverter auxiliary power supply circuit used for protecting a photovoltaic inverter and an energy storage inverter. Background Art

[0002] With the development of human industrial civilization, environmental pollution has become increasingly serious. In order to reduce the environmental pollution caused by industrial development, governments of various countries have successively promulgated a series of policies for developing clean energy, which has further promoted the rapid development of the photovoltaic industry, and a large number of photovoltaic inverters and energy storage inverters have been installed. At present, the power supply of the auxiliary power supply used in photovoltaic inverters and energy storage inverters is usually powered by three modes: one is AC power supply, one is DC power supply, and one is DC-AC hybrid power supply. No matter which power supply mode is used, there will be a phenomenon of current overshoot at the moment of startup and ineffective protection of the power supply when the input voltage is too high. Moreover, when multiple machines are connected in parallel or there is a load mutation, it often causes a mutation of the auxiliary power supply voltage, thereby causing damage to the auxiliary circuit due to overvoltage and overcurrent. At present, the startup overvoltage suppression circuit of the existing inverter auxiliary power supply circuit can only suppress the voltage overshoot phenomenon at the moment of startup, cannot well suppress the mutation of the power supply voltage after normal operation, and cannot take effective protection when the auxiliary power supply voltage is too high. Summary of the Invention

[0003] The technical problem to be solved by the present invention is that the startup overvoltage suppression circuit of the existing inverter auxiliary power supply circuit can only suppress the voltage overshoot phenomenon at the moment of startup, cannot well suppress the mutation of the power supply voltage after normal operation, and cannot take effective protection when the auxiliary power supply voltage is too high.

[0004] To solve the above technical problem, a technical solution of the present invention is to provide a protection circuit against voltage and current mutation, which is characterized by including an input control unit, a DC voltage stabilization unit, a voltage too high detection unit, a voltage conversion power supply unit, a voltage mutation detection unit, a charging and voltage mutation current limiting unit, a voltage charging completion detection unit, and a fast turn-off circuit, whose states switch between conduction and disconnection, wherein:

[0005] The power supply is connected to the input end of the input control unit, the output end of the input control unit is connected to the input end of the DC voltage stabilization unit, and the control end of the input control unit is connected to the output end of the voltage too high detection unit; the input control unit turns off and conducts according to whether the voltage detection signal output by the voltage too high detection unit is higher than the set value: when the voltage detection signal is higher than the set value, the input control unit turns off; when the voltage detection signal is lower than the set value, the input control unit conducts;

[0006] The output terminal of the DC voltage stabilization unit is connected to the input terminals of the overvoltage detection unit, the voltage conversion power supply unit, and the voltage charging completion detection unit; the DC voltage stabilization unit includes a filtering unit, and the output terminal of the filtering unit is connected to the overvoltage detection unit, the voltage conversion power supply unit, and the voltage charging completion detection unit. The input terminal of the filtering unit inputs direct current, which is directly provided by the power supply or provided after partial conversion of the alternating current provided by the power supply by the rectification unit;

[0007] The voltage mutation detection unit is connected in series in the DC voltage stabilization unit, and the output terminal of the voltage mutation detection unit is connected to the voltage mutation current limiting control terminal of the charging and voltage mutation current limiting unit; when the voltage mutation detection unit detects that the voltage reaches the set mutation value, the voltage mutation detection unit causes the current limiting resistor in the charging and voltage mutation current limiting unit to cut into the DC voltage stabilization unit through the voltage mutation current limiting control terminal of the charging and voltage mutation current limiting unit for current limiting protection; when the power supply voltage mutation ends, the current limiting resistor is cut out from the DC voltage stabilization unit;

[0008] The input terminal of the voltage mutation detection unit is connected to direct current; the output terminal of the voltage mutation detection unit is connected to the input terminal of the filtering unit;

[0009] The output terminal of the voltage charging completion detection unit is connected to the charging current limiting control terminal of the charging and voltage mutation current limiting unit; when the output of the DC voltage stabilization unit reaches the set working voltage, the voltage charging completion detection unit causes the current limiting resistor in the charging and voltage mutation current limiting unit to cut out from the DC voltage stabilization unit through the charging current limiting control terminal of the charging and voltage mutation current limiting unit;

[0010] The charging current limiting control terminal of the charging and voltage mutation current limiting unit is also electrically connected to the output terminal of the fast turn-off circuit, and the input terminal of the fast turn-off circuit is electrically connected to the output terminal of the DC voltage stabilization unit; when the power supply connected to the DC voltage stabilization unit is disconnected, the voltage on the capacitor of the filtering unit gradually decreases. When it drops to the set value, the fast turn-off circuit causes the current limiting resistor in the charging and voltage mutation current limiting unit to cut into the DC voltage stabilization unit through the charging current limiting control terminal of the charging and voltage mutation current limiting unit; when the power supply is connected to the DC voltage stabilization unit again, the current limiting resistor provides current limiting protection for the circuit.

[0011] Preferably, if the input terminal of the input control unit is connected to single-phase AC power supply or single-phase AC and DC hybrid power supply, then the input control unit includes a relay K1, a diode D5, a diode D6, a MOS transistor Q1, a resistor R9, a resistor R11, a capacitor C6, a capacitor C5, a resistor R10, and a diode D14;

[0012] The single-phase AC power supply is respectively connected to the 2nd pin and the 7th pin of the relay K1, and the 3rd pin and the 6th pin of the relay K1 are connected to the input end of the DC voltage stabilization unit; A diode D5 and a diode D6 are connected in series between the 8th pin and the 1st pin of the relay K1; The 1st pin of the relay K1 is connected to the output end of the voltage conversion power supply unit via a resistor R10. At the same time, the resistor R10 is grounded via a capacitor C5; The 8th pin of the relay K1 is connected to the drain of the MOS transistor Q1; The source of the MOS transistor Q1 is grounded; A diode D14, a capacitor C6 and a resistor R11 connected in parallel are connected across the gate and the source of the MOS transistor Q1; The gate of the MOS transistor Q1 is connected to the output end of the overvoltage detection unit via a resistor R9.

[0013] Preferably, when the input end of the input control unit is connected to a DC power supply; The input control unit includes a relay K1, a diode D5, a diode D6, a MOS transistor Q1, a resistor R9, a resistor R11, a capacitor C6, a capacitor C5, a resistor R10 and a diode D14;

[0014] The single-phase AC power supply is respectively connected to the 2nd pin and the 7th pin of the relay K1, and the 3rd pin and the 6th pin of the relay K1 are connected to the input end of the DC voltage stabilization unit; A diode D5 and a diode D6 are connected in series between the 8th pin and the 1st pin of the relay K1; The 1st pin of the relay K1 is connected to the output end of the voltage conversion power supply unit via a resistor R10. At the same time, the resistor R10 is grounded via a capacitor C5; The 8th pin of the relay K1 is connected to the drain of the MOS transistor Q1; The source of the MOS transistor Q1 is grounded; A diode D14, a capacitor C6 and a resistor R11 connected in parallel are connected across the gate and the source of the MOS transistor Q1; The gate of the MOS transistor Q1 is connected to the output end of the overvoltage detection unit via a resistor R9.

[0015] Preferably, when the input end of the input control unit is connected to a three-phase AC power supply or a three-phase AC and DC hybrid power supply: The input control unit includes a relay K1 and a relay K2; Any two-phase power supplies in the three-phase AC power supply are connected to the 2nd pin and the 7th pin of the relay K1, and the remaining one-phase power supply is connected to the 2nd pin of the relay K2; The 3rd pin, the 6th pin of the relay K1 and the 3rd pin of the relay K2 are connected to the input end of the DC voltage stabilization unit;

[0016] Relay K1 is correspondingly provided with diode D5, diode D6, MOS transistor Q1, resistor R9, resistor R11, capacitor C6, capacitor C5, resistor R10 and diode D14; diode D5 and diode D6 are connected in series between the 8th pin and the 1st pin of relay K1; the 1st pin of relay K1 is connected to the output terminal of the voltage conversion power supply unit via resistor R10, and at the same time, resistor R10 is grounded via capacitor C5; the 8th pin of relay K1 is connected to the drain of MOS transistor Q1; the source of MOS transistor Q1 is grounded; diode D14, capacitor C6 and resistor R11 connected in parallel are connected across the gate and the source of MOS transistor Q1; the gate of MOS transistor Q1 is connected to the output terminal of the overvoltage detection unit via resistor R9;

[0017] Relay K2 is correspondingly provided with diode D10, diode D11, MOS transistor Q5, resistor R18, resistor R19, capacitor C10, capacitor C9, resistor R20 and diode D18; diode D10 and diode D11 are connected in series between the 8th pin and the 1st pin of relay K2; the 1st pin of relay K2 is connected to the output terminal of the voltage conversion power supply unit via resistor R20, and at the same time, resistor R20 is grounded via capacitor C9; the 8th pin of relay K2 is connected to the drain of MOS transistor Q5. The source of MOS transistor Q5 is grounded; diode D18, capacitor C10 and resistor R19 connected in parallel are connected across the gate and the source of MOS transistor Q5; the gate of MOS transistor Q5 is connected to the output terminal of the overvoltage detection unit via resistor R18;

[0018] The overvoltage detection unit adopts a resistor voltage division network connected in parallel at the output terminal of the DC voltage stabilization unit. This resistor voltage division network includes resistors R3, R5 and R8 connected in series, and the output terminal of the overvoltage detection unit is led out between resistor R5 and resistor R8.

[0019] Preferably, the charging and voltage mutation current limiting unit includes current limiting resistor R12, triode Q4, diode D15, resistor R15, triode Q2 and diode D16; the base of triode Q4 is the charging current limiting control end; diode D15 is connected across the base and the emitter of triode Q4; the emitter of triode Q4 is grounded; current limiting resistor R12 is connected across the emitter and the collector of triode Q4; one end of current limiting resistor R12 is also connected to the input terminal of the DC voltage stabilization unit, and the other end is connected to the input terminal of the filtering unit of the DC voltage stabilization unit; the base of triode Q4 is connected to the collector of triode Q2 via a resistor; the base of triode Q2 is the voltage mutation current limiting control end; diode D16 is connected across the base and the emitter of triode Q2; the emitter of triode Q2 is grounded.

[0020] Preferably, the voltage mutation detection unit includes resistors R1, R4, and R6 connected in series. An output terminal of the voltage mutation detection unit is led out between resistor R4 and resistor R6 and is connected to a voltage mutation current limiting control terminal of the charging and voltage mutation current limiting unit.

[0021] Preferably, the voltage charging completion detection unit includes resistors R14, R21, diode D7, resistor R13, and capacitor C7 connected in series; resistor R14 is connected to an output terminal of the DC voltage stabilization unit. Two ends of capacitor C7 are respectively grounded and connected to a charging current limiting control terminal of the charging and voltage mutation current limiting unit; an initial voltage value of a capacitor in a filtering unit of the DC voltage stabilization unit is 0V. After the capacitor in the filtering unit starts to charge, the voltage on the capacitor in the filtering unit of the DC voltage stabilization unit gradually rises. At this time, the output of the DC voltage stabilization unit charges capacitor C7 via resistor R14, resistor R21, diode D7, and resistor R13; when the voltage on the capacitor in the filtering unit of the DC voltage stabilization unit reaches a set operating voltage, the voltage on capacitor C7 also just charges to meet the requirement of the gate turn-on voltage of triode Q4, causing triode Q4 to conduct and short-circuiting current limiting resistor R12, and current limiting resistor R12 is automatically cut out from the DC voltage stabilization unit.

[0022] Preferably, the fast turn-off circuit includes triode Q3, diode D17, capacitor C8, resistor R16, and resistor R17; the base of triode Q3 is used as an input terminal of the fast turn-off circuit, and the base of triode Q3 is connected between resistor R21 and resistor R14 connected in series; the collector of triode Q3 is grounded via resistor R17; the emitter of triode Q3 is connected to the base of triode Q4 via resistor R13; a parallel combination of diode D17, capacitor C8, and resistor R16 is connected across the base and collector of triode Q4;

[0023] When single-phase AC power supply, three-phase AC power supply, DC power supply, or AC-DC hybrid power supply connected to the DC voltage stabilization unit is disconnected, the voltage on the capacitor in the filtering circuit gradually decreases. When it drops to a set value, after the voltage at the base of triode Q3 drops to a set value, triode Q3 conducts and discharges capacitor C7, quickly pulling the base voltage of triode Q4 below the turn-on threshold and turning it off, and cutting current limiting resistor R12 into the DC voltage stabilization unit; when single-phase AC power supply, three-phase AC power supply, DC power supply, or AC-DC hybrid power supply is connected to the DC voltage stabilization unit again, current limiting resistor R12 provides current limiting protection for the circuit.

[0024] Preferably, when single-phase AC and DC hybrid power supply or three-phase AC and DC hybrid power supply is connected to an input terminal of the input control unit, an isolation and reverse connection prevention unit connected in series to the DC power supply is further included for isolating the DC power supply and the AC power supply.

[0025] Another technical solution of the present invention is to provide a working method for the aforementioned protection circuit against voltage and current mutations, which is characterized by the following steps:

[0026] The input voltage Vin is input to the DC voltage stabilizing unit, and the DC voltage output by the DC voltage stabilizing unit starts to rise from 0V; at this time, the rectifying resistor in the charging and voltage mutation current limiting unit is cut into the DC voltage stabilizing unit to limit the charging current, and the charging current is limited to a maximum value of the input voltage Vin divided by the current limiting resistor R12; under the condition of current limiting, the DC voltage output by the DC voltage stabilizing unit is gradually raised to the set working voltage value; after reaching the set working voltage value, the current limiting resistor in the charging and voltage mutation current limiting unit is cut out of the DC voltage stabilizing unit to supply power to the subsequent circuit;

[0027] At this time, if there is a mutation in the input voltage but it has not reached the highest protection voltage value set by the voltage over - high detection unit, the voltage mutation detection unit acts on the charging and voltage mutation current limiting unit, and cuts the current limiting resistor in the charging and voltage mutation current limiting unit into the DC voltage stabilizing unit to limit the mutated voltage; when the input voltage is further raised to reach the highest protection voltage value set by the voltage over - high detection unit, the input control unit switches to the off state to disconnect the input voltage from the subsequent circuit, achieving the effect of protecting the subsequent circuit; when the DC voltage output by the DC voltage stabilizing unit is lower than the highest protection voltage value set by the voltage over - high detection unit, the input control unit switches to the on state to reconnect the input voltage and the subsequent circuit to continue power supply; if the input voltage is still higher than the set highest value at this time, the input control unit switches to the off state again, and this cycle repeats until the input voltage is normal or there is human intervention;

[0028] Before the input control unit switches to the off state again, if the input voltage has returned to normal, the protection circuit against voltage and current mutations repeats the above actions and re - enters the startup cycle; if the protection circuit against voltage and current mutations has started to work normally, at this time, if the power is turned off manually to cut off the connection between the input voltage and the subsequent circuit, when the setting voltage is lower than the set value, it causes the fast - turn - off unit to act, so that the fast - turn - off unit quickly turns off, and cuts the current limiting resistor in the charging and voltage mutation current limiting unit into the DC voltage stabilizing unit to prepare for the next startup.

[0029] The protection circuit against voltage and current mutations provided by the present invention can well complete the suppression of over - voltage and over - current during the startup of the auxiliary power supply circuit, can suppress the mutation of the supply voltage after normal operation, can effectively protect against the over - high supply voltage of the auxiliary power supply, and can well protect the auxiliary power supply circuit from damage when the supply voltage mutates or is too high. Moreover, the structure of the present invention is simple and easy to implement, and it can be applied not only in single - phase AC power supply, but also in three - phase AC power supply, DC power supply or AC - DC hybrid power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a block diagram of the principle of the present invention;

[0031] Figure 2 schematically shows the circuit schematic diagram of the present invention applied in single-phase AC power supply;

[0032] Figure 3 schematically shows the circuit schematic diagram of the present invention applied in three-phase AC power supply;

[0033] Figure 4 schematically shows the circuit schematic diagram of the present invention applied in DC power supply;

[0034] Figure 5 schematically shows the circuit schematic diagram of the present invention applied in single-phase AC and DC hybrid power supply;

[0035] Figure 6 schematically shows the circuit schematic diagram of the present invention applied in three-phase AC and DC hybrid power supply;

[0036] Figure 7 schematically shows the working process of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0037] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0038] As Figure 1 shown, a voltage and current sudden change protection circuit disclosed by the present invention includes an input control unit whose state switches between conduction and disconnection, a DC voltage stabilization unit, a voltage over-high detection unit, a voltage conversion power supply unit, a voltage sudden change detection unit, a charging and voltage sudden change current limiting unit, a voltage charging completion detection unit, a fast turn-off circuit, and an isolation anti-reverse unit.

[0039] Single-phase AC power supply, three-phase AC power supply, DC power supply or AC-DC hybrid power supply is connected to the input end of the input control unit. The output end of the input control unit is connected to the input end of the DC voltage stabilization unit, and the control end of the input control unit is connected to the output end of the voltage over-high detection unit.

[0040] The input control unit operates according to the voltage output by the overvoltage detection unit. When the voltage output by the overvoltage detection unit is too high, that is, after the overvoltage detection unit detects that the voltage output by the DC voltage regulator unit reaches the maximum set value, the input control unit will be disconnected, thereby protecting the circuit behind the input control unit from being damaged. After the overvoltage detection unit detects that the voltage output by the DC voltage regulator unit drops below the maximum set value, the input control unit resumes the conducting state, and the circuit behind the input control unit will recharge and work again, entering the next cycle.

[0041] As Figure 2 shown, when the present invention is applied to single-phase AC power supply and as Figure 5 shown, when the present invention is applied to single-phase AC and DC hybrid power supply: The input control unit consists of a relay K1, a diode D5, a diode D6, a MOS transistor Q1, a resistor R9, a resistor R11, a capacitor C6, a capacitor C5, a resistor R10, and a diode D14. The single-phase AC power supply is respectively connected to the 2nd pin and the 7th pin of the relay K1, and the 3rd pin and the 6th pin of the relay K1 are connected to the input end of the DC voltage regulator unit. A diode D5 and a diode D6 are connected in series between the 8th pin and the 1st pin of the relay K1. The 1st pin of the relay K1 is connected to the output end of the voltage conversion power supply unit via a resistor R10. At the same time, the resistor R10 is grounded via a capacitor C5. The 8th pin of the relay K1 is connected to the drain of the MOS transistor Q1. The source of the MOS transistor Q1 is grounded. A diode D14, a capacitor C6, and a resistor R11 are connected in parallel between the gate and the source of the MOS transistor Q1. The gate of the MOS transistor Q1 is connected to the output end of the overvoltage detection unit via a resistor R9.

[0042] As Figure 4 shown, when the present invention is applied to DC power supply, the DC power supply is respectively connected to the 2nd pin and the 7th pin of the relay K1.

[0043] After the overvoltage detection unit detects that the voltage output by the DC voltage regulator unit reaches the maximum set value, the relay K1 will be disconnected, thereby protecting the circuit behind the relay K1 from being damaged. After the overvoltage detection unit detects that the voltage output by the DC voltage regulator unit drops below the maximum set value, the relay K1 will resume the conducting state, and the subsequent circuit will recharge and work again, entering the next cycle.

[0044] As Figure 3 shown, when the present invention is applied to three-phase AC power supply and as Figure 6 shown, when the present invention is applied to three-phase AC and DC hybrid power supply, two relays are used, namely the relay K1 and the relay K2.

[0045] Any two-phase power supplies in the three-phase AC power supply are connected to the 2nd and 7th pins of relay K1, and the remaining one-phase power supply is connected to the 2nd pin of relay K2. The 3rd and 6th pins of relay K1 and the 3rd pin of relay K2 are connected to the input end of the DC voltage stabilization unit.

[0046] Relay K1 is correspondingly provided with diode D5, diode D7, MOS transistor Q1, resistor R9, resistor R11, capacitor C6, capacitor C5, resistor R10, and diode D14.

[0047] Relay K2 is correspondingly provided with diode D10, diode D11, MOS transistor Q5, resistor R18, resistor R19, capacitor C10, capacitor C9, resistor R20, and diode D18. Diode D10 and diode D11 are connected in series between the 8th and 1st pins of relay K2. The 1st pin of relay K2 is connected to the output end of the voltage conversion power supply unit via resistor R20. At the same time, resistor R20 is grounded via capacitor C9. The 8th pin of relay K2 is connected to the drain of MOS transistor Q5. The source of MOS transistor Q5 is grounded. A parallel-connected diode D18, capacitor C10, and resistor R19 are connected across the gate and source of MOS transistor Q5. The gate of MOS transistor Q5 is connected to the output end of the overvoltage detection unit via resistor R18.

[0048] The overvoltage detection unit uses a resistor voltage division network connected in parallel at the output end of the DC voltage stabilization unit. In this embodiment, this resistor voltage division network includes series-connected resistors R3, R5, and R8, and the output end of the overvoltage detection unit is led out between resistor R5 and resistor R8.

[0049] After the overvoltage detection unit detects that the voltage output by the DC voltage stabilization unit reaches the highest set value, it will disconnect relay K1 and relay K2, thereby protecting the circuits behind relay K1 and relay K2 from being damaged. After the overvoltage detection unit detects that the voltage output by the DC voltage stabilization unit drops below the highest set value, relay K1 and relay K2 will resume the conducting state, and the subsequent circuits will recharge and work, entering the next cycle.

[0050] The input end of the DC voltage stabilization unit is connected to the output end of the input control unit, and the output end of the DC voltage stabilization unit is connected to the input end of the overvoltage detection unit and the input end of the voltage conversion power supply unit.

[0051] When the present invention is applied to single-phase AC power supply as shown in Figure 2 or when the present invention is applied to as shown in Figure 5When the single-phase AC and DC hybrid power supply is as shown, the DC voltage stabilizing unit includes a rectifying unit composed of diodes D1, D2, D3, D4 and a filtering unit composed of capacitors C1, C2, C3, C4, resistors R2, R7.

[0052] The DC voltage stabilizing unit is used to rectify and filter the single-phase AC voltage and regulate it into a DC voltage.

[0053] When the present invention is applied to Figure 3 the three-phase AC power supply as shown or when the present invention is applied to Figure 6 the three-phase AC and DC hybrid power supply as shown, the DC voltage stabilizing unit includes a rectifying unit composed of diodes D1, D2, D3, D4, D8, D9 and a filtering unit composed of capacitors C1, C2, C3, C4, resistors R2, R7.

[0054] The DC voltage stabilizing unit is used to rectify and filter the three-phase AC voltage and regulate it into a DC voltage.

[0055] When the present invention is applied to Figure 4 the DC power supply as shown, the DC voltage stabilizing unit includes a filtering unit composed of capacitors C1, C2, C3, C4, resistors R2, R7.

[0056] The voltage mutation detection unit is connected in series to the DC voltage stabilizing unit and is used to detect whether there is a mutation in the power supply voltage. The output end of the voltage mutation detection unit is connected to the voltage mutation current limiting control end of the charging and voltage mutation current limiting unit. When the power supply voltage has a mutation at the moment of startup or after normal startup and reaches the set mutation value, it will be detected by the voltage mutation detection unit. The voltage mutation detection unit enables the current limiting resistor in the charging and voltage mutation current limiting unit to cut into the DC voltage stabilizing unit through the voltage mutation current limiting control end for current limiting protection. When the power supply voltage mutation ends, the current limiting resistor cuts out from the DC voltage stabilizing unit.

[0057] The charging and voltage mutation current limiting unit consists of a current limiting resistor R12, a triode Q4, a diode D15, a resistor R15, a triode Q2, and a diode D16. The base of the triode Q4 is the charging current limiting control terminal. The diode D15 is connected across the base and the emitter of the triode Q4. The emitter of the triode Q4 is grounded. The current limiting resistor R12 is connected across the emitter and the collector of the triode Q4. One end of the current limiting resistor R12 is also connected to the input terminal of the DC voltage stabilization unit, and the other end is connected to the input terminal of the filtering unit of the DC voltage stabilization unit. The base of the triode Q4 is connected to the collector of the triode Q2 via a resistor. The base of the triode Q2 is the voltage mutation current limiting control terminal. The diode D16 is connected across the base and the emitter of the triode Q2. The emitter of the triode Q2 is grounded. When the circuit provided by the present invention is powered on for the first time, the capacitor voltage on the filtering unit of the DC voltage stabilization unit is 0V, the triode Q4 is in the off state, and the current limiting resistor R12 is connected in series to the DC voltage stabilization unit to limit the input voltage. The current limiting value is Vin / R12, where Vin is the voltage value input to the DC voltage stabilization unit. When the capacitor voltage on the filtering unit of the DC voltage stabilization unit rises to the set working voltage, the triode Q4 is turned on, and the current limiting resistor R12 is automatically cut out from the DC voltage stabilization unit, and the circuit disclosed by the present invention operates normally with power supply. At this time, if the input voltage suddenly mutates and the mutation value does not reach the maximum protection value after passing through the DC voltage stabilization unit, it will be detected by the voltage mutation detection unit and transmitted to the base of the triode Q2, so that the base of the triode Q2 reaches the required voltage for threshold voltage opening, thereby pulling down the base voltage of the triode Q4, quickly turning off the triode Q4, and cutting the current limiting resistor R12 into the DC voltage stabilization unit for current limiting protection. When the input voltage mutation ends, the triode Q4 is turned on again to short-circuit the current limiting resistor R12 and cut the current limiting resistor R12 out of the DC voltage stabilization unit.

[0058] When the present invention is applied to single-phase AC power supply as shown in Figure 2 When the present invention is applied to single-phase AC and DC hybrid power supply as shown in Figure 5 When the present invention is applied to three-phase AC power supply as shown in Figure 3 or when the present invention is applied to three-phase AC and DC hybrid power supply as shown in Figure 6 the voltage mutation detection unit is connected in series between the rectification unit and the filtering unit. When the present invention is applied to DC power supply as shown in Figure 4 the voltage mutation detection unit is connected in series before the wave unit.

[0059] The voltage mutation detection unit is composed of resistors R1, R4, and R6 connected in series, and is used to detect whether there is a mutation in the power supply voltage. The output terminal of the voltage mutation detection unit is led out between resistor R4 and resistor R6 and is connected to the voltage mutation current limiting control terminal of the charging and voltage mutation current limiting unit. Whether at the moment of startup or after normal startup, if the input voltage has a mutation and reaches the set mutation value, the triode Q2 will be turned on, quickly discharging the base of the triode Q4, turning off the triode Q4 quickly, and cutting the current limiting resistor R12 into the DC voltage stabilizing unit to limit the current of the circuit for protection.

[0060] The input terminal of the voltage charging completion detection unit is connected to the output terminal of the DC voltage stabilizing unit, and the output terminal of the voltage charging completion detection unit is connected to the charging current limiting control terminal of the charging and voltage mutation current limiting unit. When the output of the DC voltage stabilizing unit reaches the set working voltage, the voltage charging completion detection unit causes the current limiting resistor in the charging and voltage mutation current limiting unit to cut out from the DC voltage stabilizing unit via the charging current limiting control terminal of the charging and voltage mutation current limiting unit. After the circuit disclosed in the present invention works normally in this way, the current limiting resistor has no loss and heat generation, and does not affect the work of the subsequent circuit.

[0061] The voltage charging completion detection unit is composed of resistor R14, resistor R21, diode D7, resistor R13, and capacitor C7 connected in series. Resistor R14 is connected to the output terminal of the DC voltage stabilizing unit, and the two ends of capacitor C7 are respectively grounded and connected to the charging current limiting control terminal of the charging and voltage mutation current limiting unit. The initial voltage value of the capacitor in the filtering unit of the DC voltage stabilizing unit is 0V. After the capacitor in the filtering unit starts to charge, the voltage on the capacitor in the filtering unit of the DC voltage stabilizing unit gradually rises. At this time, the output of the DC voltage stabilizing unit charges capacitor C7 via resistor R14, resistor R21, diode D7, and resistor R13. When the voltage on the capacitor in the filtering unit of the DC voltage stabilizing unit reaches the set working voltage, the voltage on capacitor C7 also just charges to meet the requirement of the gate turn-on voltage of triode Q4, turning on triode Q4, short-circuiting current limiting resistor R12, and automatically cutting current limiting resistor R12 out of the DC voltage stabilizing unit. After the circuit provided by the present invention works normally in this way, current limiting resistor R12 also has no loss and heat generation, and does not affect the work of the subsequent circuit.

[0062] The charging current limiting control terminal of the charging and voltage mutation current limiting unit is also connected to the output terminal circuit of the fast turn-off circuit, and the input terminal of the fast turn-off circuit is connected to the output terminal circuit of the DC voltage stabilizing unit. When the single-phase AC power supply, three-phase AC power supply, DC power supply or AC-DC hybrid power supply connected to the DC voltage stabilizing unit is disconnected, the voltage on the capacitor of the filtering unit gradually decreases. After it drops to the set value, the fast turn-off circuit causes the current limiting resistor in the charging and voltage mutation current limiting unit to cut into the DC voltage stabilizing unit via the charging current limiting control terminal of the charging and voltage mutation current limiting unit. When the single-phase AC power supply, three-phase AC power supply, DC power supply or AC-DC hybrid power supply is connected to the DC voltage stabilizing unit again, the current limiting resistor can well limit the current in the circuit, will not cause overshoot of the current, and can well meet the current limiting requirements of frequent on-off and the on-off current limiting requirements of the warm machine.

[0063] The fast turn-off circuit consists of a triode Q3, a diode D17, a capacitor C8, a resistor R16 and a resistor R17. The base of the triode Q3 is used as the input terminal of the fast turn-off circuit, and the base of the triode Q3 is connected between the series-connected resistors R21 and R14. The collector of the triode Q3 is grounded via the resistor R17. The emitter of the triode Q3 is connected to the base of the triode Q4 via the resistor R13. A parallel-connected diode D17, capacitor C08 and resistor R16 are connected in parallel between the base and the collector of the triode Q4. When the single-phase AC power supply, three-phase AC power supply, DC power supply or AC-DC hybrid power supply connected to the DC voltage stabilizing unit is disconnected, the voltage on the capacitor in the filtering circuit gradually decreases. After it drops to the set value and the voltage at the base of the triode Q3 drops to the set value, the triode Q3 conducts, discharges the capacitor C7, quickly pulls down the base voltage of the triode Q4 below the turn-on threshold and turns it off, and cuts the current limiting resistor R12 into the DC voltage stabilizing unit. When the single-phase AC power supply, three-phase AC power supply, DC power supply or AC-DC hybrid power supply is connected to the DC voltage stabilizing unit again, the current limiting resistor R12 can well limit the current in the circuit, will not cause overshoot of the current, and can well meet the current limiting requirements of frequent on-off and the on-off current limiting requirements of the warm machine.

[0064] The voltage conversion power supply unit is a small DC / DC switching power supply, which is used to convert the high voltage output by the DC voltage stabilizing unit into +12VDC voltage to supply power to the relays K1 and K2 of the input control unit.

[0065] When the present invention is applied in Figure 5 the single-phase AC and DC hybrid power supply shown in Figure 6When in the three-phase AC and DC hybrid power supply as shown, it further includes an isolation and reverse current prevention unit, which is used to isolate the DC power supply and the AC power supply to prevent the AC power supply and the DC power supply from flowing back in reverse to each other. When the AC power supply voltage is higher than the DC power supply voltage, the AC power supply input will supply power; when the DC power supply voltage is higher than the AC power supply voltage, the DC power supply voltage input will supply power; when the AC voltage and the DC voltage are equal in a certain state, the DC voltage input and the AC voltage input will supply power simultaneously. The isolation and reverse current prevention unit consists of diode D12 and diode D13 connected in series to the DC power supply.

[0066] The working principle of a voltage and current mutation protection circuit provided by the present invention is:

[0067] The input voltage Vin enters the input DC voltage stabilizing unit, and the DC voltage output by the DC voltage stabilizing unit starts to rise from 0V. At this time, the rectifying resistor in the charging and voltage mutation current limiting unit cuts into the DC voltage stabilizing unit to limit the charging current. The charging current is limited to a maximum value of the input voltage Vin divided by the current limiting resistor R12. Under the current limiting condition, the DC voltage output by the DC voltage stabilizing unit gradually rises to the set working voltage value. After reaching the set working voltage value, the current limiting resistor in the charging and voltage mutation current limiting unit cuts out of the DC voltage stabilizing unit to supply power to the subsequent circuit. At this time, the current limiting resistor in the charging and voltage mutation current limiting unit has no loss and does not affect the operation of the subsequent circuit. At this time, if there is a mutation in the input voltage but it has not reached the highest protection voltage value set by the overvoltage detection unit, the voltage mutation detection unit acts on the charging and voltage mutation current limiting unit to cut the current limiting resistor in the charging and voltage mutation current limiting unit into the DC voltage stabilizing unit to limit the mutated voltage. When the input voltage further rises to reach the highest protection voltage value set by the overvoltage detection unit, the input control unit switches to the off state to disconnect the input voltage from the subsequent circuit, achieving the effect of protecting the subsequent circuit. After the DC voltage output by the DC voltage stabilizing unit is lower than the highest protection voltage value set by the overvoltage detection unit, the input control unit switches to the on state to reconnect the input voltage and the subsequent circuit to continue power supply. If the input voltage is still higher than the set highest value at this time, the input control unit switches to the off state again, and this cycle repeats until the input voltage is normal or there is human intervention. If the input voltage has returned to normal before the input control unit switches to the off state again, the anti-voltage and current mutation protection circuit provided by the present invention will repeat the above actions and re-enter the startup cycle. If the anti-voltage and current mutation protection circuit provided by the present invention has started to operate normally, and if the input voltage is cut off at this time to disconnect the connection between the input voltage and the subsequent circuit, when the setting voltage is lower than the set value, it will cause the fast turn-off unit to act, so that the fast turn-off unit quickly turns off, and the current limiting resistor in the charging and voltage mutation current limiting unit is cut into the DC voltage stabilizing unit to prepare for the next startup. Since the fast turn-off unit can quickly cut the current limiting resistor in or out, it can well meet the current limiting requirements for fast switching on and off, and also well solve the current limiting requirements for hot starting. If the input voltage is DC, there is no rectifying part in the rectifying and filtering unit, and the DC voltage is directly added to the filtering capacitor of the rectifying and filtering unit through the input control unit or the isolation and anti-reverse unit. If it is AC-DC hybrid power supply input, the rectifying part in the rectifying and filtering unit is still required. If it is three-phase power supply, one more control relay will be added to the input control unit and corresponding control actions will be added.

Claims

1. A protection circuit against sudden changes in voltage and current, characterized in that, It includes an input control unit whose state switches between on and off, a DC voltage stabilizing unit, a voltage over - high detection unit, a voltage conversion power supply unit, a voltage mutation detection unit, a charging and voltage mutation current - limiting unit, a voltage charging completion detection unit, and a fast turn - off circuit, where: The power supply is connected to the input end of the input control unit. The output end of the input control unit is connected to the input end of the DC voltage stabilizing unit, and the control end of the input control unit is connected to the output end of the voltage over - high detection unit. The input control unit turns off and on according to whether the voltage detection signal output by the voltage over - high detection unit is higher than the set value: when the voltage detection signal is higher than the set value, the input control unit turns off; when the voltage detection signal is lower than the set value, the input control unit turns on. The output end of the DC voltage stabilizing unit is connected to the input end of the voltage over - high detection unit, the input end of the voltage conversion power supply unit, and the input end of the voltage charging completion detection unit. The DC voltage stabilizing unit includes a filtering unit. The output end of the filtering unit is connected to the voltage over - high detection unit, the voltage conversion power supply unit, and the voltage charging completion detection unit. The input end of the filtering unit inputs direct current, which is directly provided by the power supply or is provided after the rectifying unit converts part of the alternating current provided by the power supply. The voltage mutation detection unit is connected in series in the DC voltage stabilizing unit. The output end of the voltage mutation detection unit is connected to the voltage mutation current - limiting control end of the charging and voltage mutation current - limiting unit. When the voltage mutation detection unit detects that the voltage reaches the set mutation value, the voltage mutation detection unit makes the current - limiting resistor in the charging and voltage mutation current - limiting unit cut into the DC voltage stabilizing unit through the voltage mutation current - limiting control end of the charging and voltage mutation current - limiting unit for current - limiting protection. When the power supply voltage mutation ends, the current - limiting resistor is cut out from the DC voltage stabilizing unit. The input end of the voltage mutation detection unit is connected to direct current. The output end of the voltage mutation detection unit is connected to the input end of the filtering unit. The output end of the voltage charging completion detection unit is connected to the charging current - limiting control end of the charging and voltage mutation current - limiting unit. When the output of the DC voltage stabilizing unit reaches the set working voltage, the voltage charging completion detection unit makes the current - limiting resistor in the charging and voltage mutation current - limiting unit cut out from the DC voltage stabilizing unit through the charging current - limiting control end of the charging and voltage mutation current - limiting unit. The charging current - limiting control end of the charging and voltage mutation current - limiting unit is also in circuit communication with the output end of the fast turn - off circuit. The input end of the fast turn - off circuit is in circuit communication with the output end of the DC voltage stabilizing unit. When the power supply connected to the DC voltage stabilizing unit is disconnected, the voltage on the capacitor of the filtering unit gradually decreases. When it drops to the set value, the fast turn - off circuit makes the current - limiting resistor in the charging and voltage mutation current - limiting unit cut into the DC voltage stabilizing unit through the charging current - limiting control end of the charging and voltage mutation current - limiting unit. When the power supply is connected to the DC voltage stabilizing unit again, the current - limiting resistor provides current - limiting protection for the circuit.

2. The anti-voltage and current mutation protection circuit according to claim 1, characterized in that, When the input end of the input control unit is connected to single-phase AC power supply or single-phase AC and DC hybrid power supply, the input control unit includes a relay K1, a diode D5, a diode D6, a MOS transistor Q1, a resistor R9, a resistor R11, a capacitor C6, a capacitor C5, a resistor R10, and a diode D14; The single-phase AC power supply is respectively connected to the 2nd pin and the 7th pin of the relay K1. The 3rd pin and the 6th pin of the relay K1 are connected to the input end of the DC voltage stabilization unit. A diode D5 and a diode D6 are connected in series between the 8th pin and the 1st pin of the relay K1. The 1st pin of the relay K1 is connected to the output end of the voltage conversion power supply unit via a resistor R10. At the same time, the resistor R10 is grounded via a capacitor C5. The 8th pin of the relay K1 is connected to the drain of the MOS transistor Q1. The source of the MOS transistor Q1 is grounded. A diode D14, a capacitor C6, and a resistor R11 connected in parallel are connected across the gate and the source of the MOS transistor Q1. The gate of the MOS transistor Q1 is connected to the output end of the overvoltage detection unit via a resistor R9.

3. The anti-voltage and current mutation protection circuit according to claim 1, characterized in that, When the input end of the input control unit is connected to DC power supply; the input control unit includes a relay K1, a diode D5, a diode D6, a MOS transistor Q1, a resistor R9, a resistor R11, a capacitor C6, a capacitor C5, a resistor R10, and a diode D14; The DC power supply is respectively connected to the 2nd pin and the 7th pin of the relay K1. The 3rd pin and the 6th pin of the relay K1 are connected to the input end of the DC voltage stabilization unit. A diode D5 and a diode D6 are connected in series between the 8th pin and the 1st pin of the relay K1. The 1st pin of the relay K1 is connected to the output end of the voltage conversion power supply unit via a resistor R10. At the same time, the resistor R10 is grounded via a capacitor C5. The 8th pin of the relay K1 is connected to the drain of the MOS transistor Q1. The source of the MOS transistor Q1 is grounded. A diode D14, a capacitor C6, and a resistor R11 connected in parallel are connected across the gate and the source of the MOS transistor Q1. The gate of the MOS transistor Q1 is connected to the output end of the overvoltage detection unit via a resistor R9.

4. A protection circuit against voltage and current mutations as claimed in claim 1, characterized in that, When the input end of the input control unit is connected to three-phase AC power supply or three-phase AC and DC hybrid power supply: the input control unit includes a relay K1 and a relay K2; any two-phase power supplies in the three-phase AC power supply are connected to the 2nd pin and the 7th pin of the relay K1, and the remaining one-phase power supply is connected to the 2nd pin of the relay K2; the 3rd pin, the 6th pin of the relay K1, and the 3rd pin of the relay K2 are connected to the input end of the DC voltage stabilization unit; Relay K1 is correspondingly provided with diode D5, diode D7, MOS transistor Q1, resistor R9, resistor R11, capacitor C6, capacitor C5, resistor R10 and diode D14; Diode D5 and diode D6 are connected in series between pin 8 and pin 1 of relay K1; Pin 1 of relay K1 is connected to the output terminal of the voltage conversion power supply unit via resistor R10. At the same time, resistor R10 is grounded via capacitor C5; Pin 8 of relay K1 is connected to the drain of MOS transistor Q1; The source of MOS transistor Q1 is grounded; Diode D14, capacitor C6 and resistor R11 connected in parallel are connected across the gate and source of MOS transistor Q1; The gate of MOS transistor Q1 is connected to the output terminal of the overvoltage detection unit via resistor R9; Relay K2 is correspondingly provided with diode D10, diode D11, MOS transistor Q5, resistor R18, resistor R19, capacitor C10, capacitor C9, resistor R20 and diode D18; Diode D10 and diode D11 are connected in series between pin 8 and pin 1 of relay K2; Pin 1 of relay K2 is connected to the output terminal of the voltage conversion power supply unit via resistor R20. At the same time, resistor R20 is grounded via capacitor C9; Pin 8 of relay K2 is connected to the drain of MOS transistor Q5; The source of MOS transistor Q5 is grounded; Diode D18, capacitor C10 and resistor R19 connected in parallel are connected across the gate and source of MOS transistor Q5; The gate of MOS transistor Q5 is connected to the output terminal of the overvoltage detection unit via resistor R18; The overvoltage detection unit uses a resistor voltage division network connected in parallel at the output terminal of the DC voltage stabilization unit. This resistor voltage division network includes resistors R3, R5 and R8 connected in series, and the output terminal of the overvoltage detection unit is led out between resistor R5 and resistor R8.

5. A protection circuit against voltage and current mutations according to any one of claims 2, 3, and 4, characterized in that, The charging and voltage mutation current limiting unit includes current limiting resistor R12, triode Q4, diode D15, resistor R15, triode Q2 and diode D16; The base of triode Q4 is the charging current limiting control terminal; Diode D15 is connected across the base and emitter of triode Q4; The emitter of triode Q4 is grounded; Current limiting resistor R12 is connected across the emitter and collector of triode Q4; One end of current limiting resistor R12 is also connected to the input terminal of the DC voltage stabilization unit, and the other end is connected to the input terminal of the filtering unit of the DC voltage stabilization unit; The base of triode Q4 is connected to the collector of triode Q2 via a resistor; The base of triode Q2 is the voltage mutation current limiting control terminal; Diode D16 is connected across the base and emitter of triode Q2; The emitter of triode Q2 is grounded.

6. A protection circuit against voltage and current mutations according to any one of claims 2, 3, and 4, characterized in that The voltage mutation detection unit includes resistors R1, R4, R6 connected in series, and the output terminal of the voltage mutation detection unit is led out between resistor R4 and resistor R6 and is connected to the voltage mutation current limiting control terminal of the charging and voltage mutation current limiting unit.

7. A protection circuit against voltage and current mutation as described in any one of claims 2, 3, and 4, characterized in that The voltage charging completion detection unit includes a series connection of resistor R14, resistor R21, diode D7, resistor R13, and capacitor C7; resistor R14 is connected to the output terminal of the DC voltage stabilization unit, and both ends of capacitor C7 are respectively grounded and connected to the charging current limiting control terminal of the charging and voltage mutation current limiting unit; the initial voltage value of the capacitor in the filtering unit of the DC voltage stabilization unit is 0V. After the capacitor in the filtering unit starts charging, the voltage of the capacitor in the filtering unit of the DC voltage stabilization unit gradually rises. At this time, the output of the DC voltage stabilization unit charges capacitor C7 via resistor R14, resistor R21, diode D7, and resistor R13; when the voltage of the capacitor in the filtering unit of the DC voltage stabilization unit reaches the set working voltage, the voltage of capacitor C7 also just charges to meet the gate turn-on voltage requirement of triode Q4, causing triode Q4 to conduct and short-circuiting current limiting resistor R12, and current limiting resistor R12 is automatically cut out from the DC voltage stabilization unit.

8. A protection circuit against voltage and current sudden changes according to any one of claims 2, 3, and 4, characterized in that The fast turn-off circuit includes triode Q3, diode D17, capacitor C8, resistor R16, and resistor R17; the base of triode Q3 is used as the input terminal of the fast turn-off circuit, and the base of triode Q3 is connected between series-connected resistor R21 and resistor R14; the collector of triode Q3 is grounded via resistor R17; the emitter of triode Q3 is connected to the base of triode Q4 via resistor R13; a parallel connection of diode D17, capacitor C8, and resistor R16 is connected across the base and collector of triode Q4; When the single-phase AC power supply, three-phase AC power supply, DC power supply, or AC-DC hybrid power supply connected to the DC voltage stabilization unit is disconnected, the voltage of the capacitor in the filtering circuit gradually decreases. After it drops to the set value, when the voltage of the base of triode Q3 drops to the set value, triode Q3 conducts and discharges capacitor C7, quickly pulling down the base voltage of triode Q4 below the turn-on threshold and turning it off, and cutting current limiting resistor R12 into the DC voltage stabilization unit; when the single-phase AC power supply, three-phase AC power supply, DC power supply, or AC-DC hybrid power supply is connected to the DC voltage stabilization unit again, current limiting resistor R12 provides current limiting protection for the circuit.

9. A protection circuit against voltage and current mutations according to any one of claims 2, 3, and 4, characterized in that When the single-phase AC and DC hybrid power supply or the three-phase AC and DC hybrid power supply is connected to the input terminal of the input control unit, an isolation and reverse protection unit connected in series to the DC power supply is further included for isolating the DC power supply and the AC power supply.

10. A working method of the protection circuit against voltage and current mutation as claimed in claim 1, characterized in that, It includes the following steps: The input voltage Vin is input to the DC voltage stabilization unit, and the DC voltage output by the DC voltage stabilization unit starts to rise from 0V; at this time, the rectifying resistor in the charging and voltage mutation current limiting unit is cut into the DC voltage stabilization unit to limit the charging current, and the charging current is limited to a maximum value of the input voltage Vin divided by the current value of current limiting resistor R12; under the condition of current limiting, the DC voltage output by the DC voltage stabilization unit is gradually raised to the set working voltage value; after reaching the set working voltage value, the current limiting resistor in the charging and voltage mutation current limiting unit is cut out from the DC voltage stabilization unit to supply power to the subsequent circuit; At this time, if there is a sudden change in the input voltage but it has not reached the maximum protection voltage value set by the overvoltage detection unit, the voltage mutation detection unit acts on the charging and voltage mutation current limiting unit, and cuts the current limiting resistor in the charging and voltage mutation current limiting unit into the DC voltage stabilizing unit to limit the mutated voltage; when the input voltage further rises and reaches the maximum protection voltage value set by the overvoltage detection unit, the input control unit switches to the off state, disconnecting the input voltage from the subsequent circuit to protect the subsequent circuit; After the DC voltage output by the DC voltage stabilizing unit is lower than the maximum protection voltage value set by the overvoltage detection unit, the input control unit switches to the on state, reconnecting the input voltage and the subsequent circuit to continue power supply; If the input voltage is still higher than the set maximum value at this time, the input control unit switches to the off state again, and this cycle repeats until the input voltage is normal or there is human intervention; Before the input control unit switches to the off state again, if the input voltage has returned to normal, the anti-voltage and current mutation protection circuit repeats the above actions and re-enters the startup cycle; if the anti-voltage and current mutation protection circuit has started working normally, at this time if the power is turned off manually, disconnecting the connection between the input voltage and the subsequent circuit, when the set voltage is lower than the set value, it causes the fast turn-off unit to act, so that the fast turn-off unit quickly turns off, and cuts the current limiting resistor in the charging and voltage mutation current limiting unit into the DC voltage stabilizing unit to prepare for the next startup.

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