Rectification step-down circuit and three-phase self-recovery overvoltage and undervoltage protector

Abstract

The utility model discloses a rectification step-down circuit and a three-phase self-recovery overvoltage and undervoltage protector. The rectification step-down circuit comprises a three-phase rectification filter circuit and a DC-DC step-down circuit. The three-phase rectification filter circuit directly takes electricity from a three-phase line and outputs high-voltage direct current; the DC-DC step-down circuit is used for converting the high-voltage direct current into low-voltage direct current to supply power to a post-stage control circuit; and the ground of the DC-DC step-down circuit is a suspended ground. The rectification step-down circuit is a three-phase rectification step-down circuit based on suspension ground control. According to the three-phase self-recovery overvoltage and undervoltage protector adopting the rectification step-down circuit, a circuit breaker can still work stably when a product is in an open-phase state or a power grid has relatively high voltage fluctuation.

Description

Technical Field

[0001] The utility model relates to the field of power management, in particular to a rectifier step-down circuit and a three-phase self-recovery over-voltage and under-voltage protector. Background Art

[0002] Existing self-recovery over- and under-voltage protectors generally use phase A and phase N as the input of the product or use IGBT step-down and voltage stabilization, DC-DC conversion, and then rectification and voltage stabilization to the working voltage required by the product (hereinafter referred to as IGBT solution).

[0003] Existing self-recovery over- and under-voltage protectors generally use single-phase A for power. In three-phase product applications, if phase A is missing, the product will not work, which poses a risk to product protection. In addition, the product has a small operating voltage range and poor overvoltage capability, which can easily lead to overvoltage damage, causing the control circuit to not work properly and fail to play a protective role. When an IGBT solution is used, when overvoltage occurs, the excess voltage is absorbed by the IGBT chip, and an overvoltage shock is likely to occur when power is turned on, causing the IGBT chip to burn out, and in severe cases, electrical fires may occur. Utility Model Content

[0004] In order to solve the above problems in the prior art, the utility model provides a rectifier step-down circuit and a three-phase self-recovery over-voltage and under-voltage protector, and the technical solution is as follows:

[0005] A rectifier and voltage-reducing circuit, comprising a three-phase rectifier and filter circuit and a DC-DC voltage-reducing circuit;

[0006] The three-phase rectifier and filter circuit directly draws power from the three-phase line and outputs high-voltage direct current;

[0007] The DC-DC step-down circuit is used to convert the high-voltage direct current into low-voltage direct current to supply power to the subsequent control circuit;

[0008] The ground of the DC-DC buck circuit is a floating ground.

[0009] Furthermore, the three-phase rectification and filtering circuit includes a three-phase full-bridge rectifier circuit, and the three-phase full-bridge rectifier circuit includes four current limiting resistors and eight rectifier diodes. The eight rectifier diodes constitute four full-bridge rectifier circuits in parallel, and the three-phase lines and the neutral line PN are respectively connected through a current limiting resistor and a full-bridge rectifier circuit.

[0010] Furthermore, the three-phase rectifier filter circuit includes a filter circuit, which includes a pair of filter capacitors connected in series, and each filter capacitor is connected in parallel with a resistor; the first and last ends of the series filter capacitors are respectively connected to the positive and negative electrodes of the high-voltage direct current.

[0011] Furthermore, the resistor connected in parallel with the filter capacitor includes one resistor or multiple resistors connected in series.

[0012] Furthermore, the filtering circuit also includes a mutual inductance choke and a capacitor; the mutual inductance choke is connected in series between the two output ends of the three-phase rectifier and filter circuit and the positive and negative electrodes of the high voltage direct current.

[0013] Furthermore, the three-phase rectifying and filtering circuit also includes a surge protection circuit, and the surge protection circuit includes a varistor, and the varistor is connected across two output ends of the three-phase rectifying and filtering circuit.

[0014] Furthermore, the DC-DC buck circuit includes a power management chip U1, a semiconductor switch tube Q1, a startup circuit, resistors R10, R11, R14, R15, R16, R17, an inductor L3, capacitors C6, C7, E4, diodes D10, D12, D14 and a voltage regulator tube ZD2;

[0015] The power management chip is a primary side controller, including a power pin, a ground pin, a drive pin, a system feedback pin, a current sampling input pin and a configuration pin;

[0016] The circuit connection relationship of the DC-DC buck circuit is:

[0017] The driving pin is connected to the cathode of the diode D9 and the first end of the resistor R9; the anode of the diode D9, the second end of the resistor R9, the first end of the resistor R10 and the control end of the semiconductor switch tube Q1 are connected; the input end of the semiconductor switch tube Q1 is connected to the output positive electrode of the three-phase rectifier filter circuit, and the output end is connected to the first end of the resistor R14 and the second end of the resistor R10; the second end of the resistor R14 is connected to the floating ground UGND;

[0018] The power supply pin is connected to the positive electrode of the high voltage direct current through the startup circuit, and is connected to the first end of the inductor L3 through the voltage regulator tube ZD2, the diode D10; the second end of the inductor L3 is connected to the floating ground UGND;

[0019] The system feedback pin is connected through a resistor R16 and a first end of an inductor L3, and is connected through a parallel resistor R15, a capacitor C7 and a floating ground UGND;

[0020] The current sampling input pin is connected to the output end of the semiconductor switch tube Q1 through the resistor R11, and is connected to the floating ground UGND through the capacitor C6;

[0021] The ground pin is connected to a floating ground UGND;

[0022] The configuration pin is connected to the floating ground UGND, and is used to configure the power management chip U1 to a buck mode;

[0023] The first end of the inductor L3 is connected to the negative electrode HGND of the high voltage direct current through the capacitor E4, the resistor R17 connected in parallel, and is connected to the anode of the diode D14; the cathode of the diode D14 is connected to the positive electrode of the power supply of the subsequent control circuit to supply power to the subsequent control circuit;

[0024] The diode D12 has an anode connected to HGND, and a cathode connected to the floating ground UGND.

[0025] Furthermore, the startup circuit includes multiple resistors, a voltage regulator ZD1 and a capacitor C3 connected in series; the first end of the multiple resistors connected in series is connected to the positive electrode HVCC of the high voltage direct current, and the other end is connected to the power pin of the power management chip, and is connected through the parallel voltage regulator ZD1, the capacitor C3 and the floating ground UGND.

[0026] Furthermore, the semiconductor switch tube Q1 is a MOS tube or an IGBT tube.

[0027] Furthermore, the power management chip is compatible with chip KP212.

[0028] The utility model also provides a three-phase self-recovering over- and under-voltage protector, the power supply circuit of which adopts the rectifier and voltage-reducing circuit as described above.

[0029] The utility model achieves the following technical effects:

[0030] In summary, the rectifier and buck circuit of this embodiment is a three-phase rectifier and buck circuit based on floating ground control. The three-phase self-recovery over- and under-voltage protector using the rectifier and buck circuit of this embodiment can still work stably when the product is missing phase or the grid has high voltage fluctuations. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a circuit diagram of the rectifier and voltage-reducing circuit of the utility model;

[0032] Figure 2 It is the circuit block diagram of the three-phase self-recovery over- and under-voltage protector. DETAILED DESCRIPTION

[0033] To further illustrate each embodiment, the present invention provides drawings. These drawings are part of the disclosure of the present invention, which are mainly used to illustrate the embodiments and can be used in conjunction with the relevant descriptions in the specification to explain the operating principles of the embodiments. With reference to these contents, ordinary technicians in this field should be able to understand other possible implementations and advantages of the present invention.

[0034] The utility model is now further described in conjunction with the accompanying drawings and specific implementation methods.

[0035] Embodiment 1:

[0036] The utility model provides a rectifier and voltage-reducing circuit which can be used for three-phase power-taking products such as three-phase self-recovery overvoltage protectors, and comprises a three-phase rectifier and filter circuit 10 and a DC-DC voltage-reducing circuit 20.

[0037] In this embodiment, the three-phase rectification and filtering circuit 10 directly draws power from the three-phase line and outputs high-voltage direct current, the positive pole of the high-voltage direct current is marked as HVCC, and the negative pole is marked as HGND.

[0038] The DC-DC step-down circuit 20 is arranged between the three-phase rectifying and filtering circuit 10 and the subsequent control circuit, and is used to step down the high-voltage direct current output by the three-phase rectifying and filtering circuit 10 into the low-voltage direct current required by the subsequent control circuit, such as Figure 1 The +24V and GND shown are the positive and negative poles of the low voltage direct current.

[0039] In this embodiment, the three-phase rectification and filtering circuit 10 includes a three-phase full-bridge rectification circuit, a filtering circuit, a surge protection circuit and other circuits.

[0040] The three-phase full-bridge rectifier circuit includes four current limiting resistors R1-R4 and eight rectifier diodes D1-D8. The rectifier diodes D1-D8 form four parallel full-bridge rectifier circuits. The three-phase lines PA, PB, PC and the neutral line PN are connected through a current limiting resistor and a full-bridge rectifier circuit respectively.

[0041] The three-phase full-bridge rectifier circuit also includes a surge protection circuit. The surge protection circuit includes a varistor RV1.

[0042] The filter circuit includes a pair of filter capacitors E1 and E2 connected in series, and the filter capacitors E1 and E2 are connected between the positive electrode HVCC and the negative electrode HGND of the high voltage direct current output by the three-phase rectifier filter circuit. The filter capacitor E1 is connected in parallel with resistors RC1 and RC2; the filter capacitor E2 is connected in parallel with resistors RC3 and RC4.

[0043] The filter circuit also includes capacitors C1 and C2 connected in series, and a common mode choke LF1. The capacitors C1 and C2 connected in series are connected between the two output ends of the three-phase full-bridge rectifier circuit, and the common mode choke LF1 is connected in series between the two output ends of the three-phase full-bridge rectifier circuit and the high voltage direct current.

[0044] In this embodiment, the DC-DC buck circuit 20 is composed of a power management chip U1, a semiconductor switch tube Q1, resistors R5-R11, R14, R15, R16, R17, capacitors C6, C7, E4, an inductor L3, diodes D10, D14 and a voltage regulator tube VZ2.

[0045] The power management chip U1 adopts a primary side controller such as KP212, including pins such as a power pin VDD, a ground pin GND, a drive pin GATE, a system feedback pin FB, a current sampling input pin CS and a configuration pin SEL.

[0046] The circuit connection relationship of the DC-DC buck circuit 20 is:

[0047] The driving pin GATE is connected to the cathode of the diode D9 and the first end of the resistor R9; the anode of the diode D9, the second end of the resistor R9, the first end of the resistor R10 and the control end of the semiconductor switch tube Q1 are connected; the input end of the semiconductor switch tube Q1 is connected to the positive electrode HVCC of the high-voltage direct current, and the output end is connected to the first end of the resistor R14 and the second end of the resistor R10; the second end of the resistor R14 is connected to the floating ground UGND;

[0048] The power supply pin VDD is connected to the positive electrode HVCC of the high voltage direct current through the startup circuit, and is connected to the first end of the inductor L3 through the voltage regulator tube ZD2, the diode D10; the second end of the inductor L3 is connected to the floating ground UGND;

[0049] The system feedback pin FB is connected through the resistor R16 and the first end of the inductor L3, and is connected through the parallel resistor R15, the capacitor C7 and the floating ground UGND;

[0050] The current sampling input pin CS is connected to the output end of the semiconductor switch tube Q1 through the resistor R11, and is connected to the floating ground UGND through the capacitor C6;

[0051] The ground pin GND is connected to the floating ground UGND;

[0052] Connect the configuration pin SEL to the floating ground UGND to configure the power management chip U1 to buck mode;

[0053] The first end of the inductor L3 is connected to the negative electrode HGND of the high voltage direct current through the capacitor E4 and the resistor R17 connected in parallel, and is connected to the anode of the diode D14; the cathode of the diode D14 is connected to the positive electrode of the power supply of the subsequent control circuit to supply power to the subsequent control circuit;

[0054] The anode of the diode D12 is connected to HGND, and the cathode is connected to the floating ground UGND.

[0055] The startup circuit includes multiple resistors R5-R8, a voltage regulator ZD1 and a capacitor C3 connected in series; the first ends of the multiple resistors R5-R8 connected in series are connected to the positive electrode HVCC of the high-voltage direct current, and the other ends are connected to the power pin VDD of the power management chip U1, and are connected through the parallel voltage regulator ZD1, the capacitor C3 and the floating ground UGND.

[0056] In this embodiment, the driving pin GATE is driven by a MOS tube, and the semiconductor switch tube Q1 adopts a semiconductor switch tube such as a high-voltage MOS tube, an IGBT tube, etc.

[0057] Working principle:

[0058] like Figure 1 As shown, this rectifier and step-down circuit uses phase A, phase B, phase C, and phase N (i.e., PA, PB, PC, and PN) as the input for power supply, i.e., a three-phase power supply mode. Through the floating ground mode of chip U1 (floating at the voltage output end), the high-voltage MOS tube Q1 is controlled to perform voltage conversion. In the circuit, R1-R4 uses high-power resistors to absorb circuit surges; D1-D8 is a three-phase full-bridge rectifier; RV1 uses a varistor as an overvoltage protection and surge protector; C1, C2, filter inductor LF1, RC1-RC4 and E1, E2 form a primary rectifier filter voltage stabilization circuit. E1 and E2 are connected in series to mainly improve the withstand voltage of the filter circuit; RC1 and RC2 are connected in series and then connected in parallel with E1, and RC3 and RC4 are connected in series and then connected in parallel with E1, which mainly plays a role in voltage division and balancing; R5-R8 series capacitor C3 provides a start-up voltage for the control chip U1, and D10 and ZD2 are connected from the output The output end is used to supply power to the control chip U1, and the voltage regulator ZD1 is used to clamp the VDD working voltage to prevent the chip from being damaged by overvoltage; the resistors R15 and R16 are used to divide the voltage to provide the control chip U1 with a zero-crossing switch signal and a voltage regulation signal; the resistor R14 is a load output current sampling resistor, which provides an overcurrent protection signal for the control chip U1; R9 and D9 are connected in series between the control chip output and the gate of the MOS tube Q1 input, so that U1 controls the on and off of Q1 to perform voltage conversion, and the load is powered after the voltage is stabilized by the filter circuit composed of inductor L3 and capacitor E4; the diode D12 provides a freewheeling current for the circuit when Q1 is turned off.

[0059] Since the power supply is three-phase, on three-phase power supply products such as three-phase self-recovery over- and under-voltage protectors, no matter which phase of the line is short of power, the power supply can still be output stably.

[0060] The rectifier and buck circuit of this embodiment has improved the voltage resistance design in the overcurrent protection circuit, the rectifier circuit, and the filter circuit. High-voltage MOS tubes are selected, which have strong overvoltage capability and an operating voltage range of AC50V to AC440V. In addition, the power management chip integrates over- and under-voltage protection, cycle-by-cycle current limiting protection, over-temperature protection, short-circuit protection, Gate output clamping, VDD clamping, and soft start functions, providing reliable protection for the stable operation of the power supply.

[0061] The utility model also provides a three-phase self-recovery over-voltage and under-voltage protector, including a power supply circuit, a three-phase voltage sampling circuit, a single-chip microcomputer, a drive circuit, a magnetic latching relay, an energy storage capacitor and a working status indication circuit, etc. Figure 2The power supply circuit adopts the above-mentioned rectifier and step-down circuit to supply power to the circuit breaker circuit composed of a single-chip microcomputer, a drive circuit, a magnetic latching relay and an energy storage capacitor, so as to ensure the stable operation of the circuit breaker.

[0062] In summary, the rectifier and buck circuit of this embodiment is a three-phase rectifier and buck circuit based on floating ground control. The three-phase self-recovery over- and under-voltage protector using the rectifier and buck circuit of this embodiment can still stably draw power from the grid when the product is missing phase or the grid has a high voltage fluctuation, and the circuit breaker can still work stably.

[0063] Although the present invention has been specifically demonstrated and described in conjunction with the preferred embodiments, those skilled in the art should understand that various changes may be made to the present invention in form and detail without departing from the spirit and scope of the present invention as defined in the appended claims, all of which are within the scope of protection of the present invention.

Claims

1. A rectifier and step-down circuit, characterized in that: Including three-phase rectification and filtering circuit and DC-DC buck circuit; The three-phase rectifier and filter circuit directly draws power from the three-phase line and outputs high-voltage direct current; The DC-DC step-down circuit is used to convert the high-voltage direct current into low-voltage direct current to supply power to the subsequent control circuit; The ground of the DC-DC buck circuit is a floating ground.

2. The rectifier and step-down circuit according to claim 1, characterized in that: The three-phase rectification and filtering circuit includes a three-phase full-bridge rectifier circuit, which includes four current-limiting resistors and eight rectifier diodes. The eight rectifier diodes constitute four full-bridge rectifier circuits in parallel, and the three-phase lines and the neutral line PN are respectively connected through a current-limiting resistor and a full-bridge rectifier circuit.

3. The rectifier and step-down circuit according to claim 1, characterized in that: The three-phase rectifier filter circuit includes a filter circuit, which includes a pair of filter capacitors connected in series, and each filter capacitor is connected in parallel with a resistor; the first and last ends of the series filter capacitors are respectively connected to the positive and negative electrodes of the high-voltage direct current.

4. The rectifier and step-down circuit according to claim 3, characterized in that: The resistor connected in parallel with the filter capacitor includes one resistor or multiple resistors connected in series.

5. The rectifier and step-down circuit according to claim 3, characterized in that: The filter circuit also includes a mutual inductance choke and a capacitor; the mutual inductance choke is connected in series between the two output ends of the three-phase rectifier filter circuit and the positive and negative electrodes of the high voltage direct current.

6. The rectifier and step-down circuit according to claim 1, characterized in that: The DC-DC step-down circuit includes a power management chip U1, a semiconductor switch tube Q1, a startup circuit, resistors R10, R11, R14, R15, R16, R17, an inductor L3, capacitors C6, C7, E4, diodes D10, D12, D14 and a voltage regulator tube ZD2; The power management chip is a primary side controller, including a power pin, a ground pin, a drive pin, a system feedback pin, a current sampling input pin and a configuration pin; The circuit connection relationship of the DC-DC buck circuit is: The driving pin is connected to the cathode of the diode D9 and the first end of the resistor R9; the anode of the diode D9, the second end of the resistor R9, the first end of the resistor R10 and the control end of the semiconductor switch tube Q1 are connected; the input end of the semiconductor switch tube Q1 is connected to the output positive electrode of the three-phase rectifier filter circuit, and the output end is connected to the first end of the resistor R14 and the second end of the resistor R10; the second end of the resistor R14 is connected to the floating ground UGND; The power supply pin is connected to the positive electrode of the high voltage direct current through the startup circuit, and is connected to the first end of the inductor L3 through the voltage regulator tube ZD2, the diode D10; the second end of the inductor L3 is connected to the floating ground UGND; The system feedback pin is connected through a resistor R16 and a first end of an inductor L3, and is connected through a parallel resistor R15, a capacitor C7 and a floating ground UGND; The current sampling input pin is connected to the output end of the semiconductor switch tube Q1 through the resistor R11, and is connected to the floating ground UGND through the capacitor C6; The ground pin is connected to a floating ground UGND; The configuration pin is connected to the floating ground UGND, and is used to configure the power management chip U1 to a buck mode; The first end of the inductor L3 is connected to the negative electrode HGND of the high voltage direct current through the capacitor E4, the resistor R17 connected in parallel, and is connected to the anode of the diode D14; the cathode of the diode D14 is connected to the positive electrode of the power supply of the subsequent control circuit to supply power to the subsequent control circuit; The diode D12 has an anode connected to HGND, and a cathode connected to the floating ground UGND.

7. The rectifier and step-down circuit according to claim 6, characterized in that: The startup circuit includes multiple resistors connected in series, a voltage regulator tube ZD1 and a capacitor C3; the first end of the multiple resistors connected in series is connected to the positive electrode HVCC of the high voltage direct current, and the other end is connected to the power pin of the power management chip, and is connected through the parallel voltage regulator tube ZD1, the capacitor C3 and the floating ground UGND.

8. The rectifier and step-down circuit according to claim 6, characterized in that: The semiconductor switch tube Q1 is a MOS tube.

9. The rectifier and step-down circuit according to claim 6, characterized in that: The power management chip is compatible with chip KP212.

10. A three-phase self-recovering over-voltage and under-voltage protector, characterized in that: The power supply circuit adopts the rectifier and step-down circuit as described in any one of claims 1 to 9.

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