CN113285586A

CN113285586A - Rectifier bridge starts protection circuit

Info

Publication number: CN113285586A
Application number: CN202110686077.9A
Authority: CN
Inventors: 张胜; 涂才根; 谭在超; 丁国华; 罗寅
Original assignee: Suzhou Covette Semiconductor Co ltd
Current assignee: Suzhou Covette Semiconductor Co ltd
Priority date: 2021-06-21
Filing date: 2021-06-21
Publication date: 2021-08-20

Abstract

The invention discloses a rectifier bridge start-up protection circuit, which comprises a rectifier bridge, an energy storage capacitor C0 and a power resistor R1, wherein an AC alternating current power supply charges a capacitor C0 through a power resistor R1 and the rectifier bridge, the power resistor R1 is connected in series on a loop between the AC alternating current power supply and the rectifier bridge, the energy storage capacitor C0 is connected at two ends of the rectifier bridge and comprises an IC control chip, an NMOS tube N1, an NOMS tube N2, a capacitor C1, a capacitor C2, an HB pin, an HO pin and an HS pin, grids of the NMOS tube N1 and the NOMS tube N2 are connected at two ends of the power resistor R1, and sources and drains of the NMOS tube N1 and the NOMS tube N2 are respectively connected with each other, the circuit has a simple structure, can be realized by only one power resistor, two NMOS power tubes and one control IC, limits the AC alternating current power supply start-up peak current, protects the safety of the rectifier bridge, the normal starting of the equipment under the conditions of high temperature and low temperature is ensured.

Description

Rectifier bridge starts protection circuit

Technical Field

The invention relates to the technical field of power circuits, in particular to a rectifier bridge starting protection circuit.

Background

Devices powered by dc power typically draw power from an AC supply network through a diode rectifier bridge having a circuit configuration as shown in fig. 1. When the input voltage of the AC power supply is at the highest voltage, the AC power supply is turned on, the peak voltage value of the two output terminals of the AC power supply is Vac 1.414, at this time, the internal power supply device is not turned on, and the voltage difference across the energy storage capacitor C0 is 0V, so the peak voltage of the AC power supply is completely loaded on the two diodes connected in series and the loop parasitic resistor r, and usually the resistance value of the resistor r is very small, only a few ohms, and the voltage drop across the two diodes is ignored, and the starting peak current of the AC power supply is obtained as:

Ipeak=Vac*1.414/r

this peak current is very large and may cause damage to the rectifier bridge, the connecting lines and other devices.

The current common solution is to add an NTC resistor (negative temperature coefficient resistor), as shown in fig. 2, the resistance of the NTC resistor decreases with increasing temperature, for example, we use a 100 Ω NTC resistor, which has a resistance of 100 Ω at 25 ℃ and the starting peak current of the rectifier bridge is limited to about Vac 1.414/100, thereby ensuring the safety of the rectifier bridge device. When the power supply equipment works normally, current flows through the NTC resistor to heat the power supply equipment, and when the temperature rises to 85 ℃, the resistance value of the NTC resistor is reduced to about 10 omega, so that the loss of electric energy is reduced. This solution presents two problems: 1. for high-power equipment, the resistance value of the NTC resistor is reduced when the power supply equipment works normally, but the electric energy loss of the NTC resistor is still considerable; 2. under low temperature conditions, the resistance of the NTC resistor becomes large, and for a 100 Ω NTC resistor, the resistance is about 34K Ω at-40 ℃, which may cause the starting current of the AC power supply to be too small, resulting in abnormal starting of the device.

Disclosure of Invention

Aiming at the situation, a more excellent solution is provided, namely the starting peak current of an AC power supply is limited, the electric energy loss after the circuit normally works is reduced, and meanwhile, the normal starting of the power supply equipment under the low-temperature condition is ensured.

As an improvement of the invention, the gates of the NMOS transistor N1 and the NOMS transistor N2 are connected to two ends of a power resistor R1, and the sources and the drains of the NMOS transistor N1 and the NOMS transistor N2 are respectively connected.

As an improvement of the invention, a power supply pin VCC of the IC control chip is connected to a power supply generated after the internal circuit normally works, an HS pin is connected to the sources of an NMOS tube N1 and an NOMS tube N2, an HO pin is connected to the grids of an NMOS tube N1 and an NOMS tube N2, and an HB pin is connected to the HS pin through a capacitor C1.

As an improvement of the present invention, the IC control chip includes an under-voltage detection module, a level shift module, a charge pump module, and a power driving module, wherein the charge pump module is configured to charge a capacitor C1, the level shift module is configured to shift a high-level signal output by the under-voltage detection module from a VCC voltage domain to a voltage domain between VHB and VHS, the under-voltage detection module is configured to detect a voltage of VCC, and the power driving module is configured to enhance a current driving capability of the high-level signal in the voltage domain between VHB and VHS.

As an improvement of the invention, the resistance range of the power resistor R1 is 10 Ω -10K Ω, and a proper resistance value can be selected according to the requirement of the starting current of the power supply equipment.

As an improvement of the invention, the range of the on-resistance values of the NMOS transistor N1 and the NOMS transistor N2 is 5m omega-10 omega, and a proper on-resistance value can be selected according to the power requirement when the equipment normally works.

As an improvement of the present invention, the capacitor C2 is connected to the VCC power supply pin and the GND pin, and the capacitor C2 is a filter capacitor of the power supply VCC.

The invention has the beneficial effects that:

1) the starting peak current of the AC power supply is limited, and the safe work of the rectifier bridge is protected;

2) the resistance value of the power resistor R1 is basically unchanged under the low-temperature condition, so that the normal starting of the equipment under the low-temperature condition is ensured;

3) after the equipment normally works, the current-limiting resistor is reduced to be an on-resistance formed by connecting two power NMOS tubes in series, and the loss of electric energy is greatly reduced.

Drawings

Fig. 1 is a schematic diagram of a rectifier bridge protection circuit in the prior art.

Fig. 2 is a schematic diagram of a circuit structure of a rectifier bridge with an NTC resistor added in the prior art.

Fig. 3 is a schematic structural diagram of a rectifier bridge start-up protection circuit according to the present invention.

Detailed Description

The present invention will be further illustrated with reference to the accompanying figures 1-3 and the following detailed description, which should be understood to illustrate the invention only and not to limit the scope of the invention.

Example (b): according to the figure 3, a rectifier bridge starting protection circuit comprises a rectifier bridge, an AC power supply charges a capacitor C0 through a power resistor R1 and the rectifier bridge, an energy storage capacitor C0 and a power resistor R1, the resistance range of the power resistor R1 is 10-10K omega, a proper resistance value can be selected according to the requirement of the starting current of power supply equipment, the resistance value of the power resistor R1 is affected very little by temperature, the power resistor R1 is connected in series on a loop between the AC power supply and the rectifier bridge, the energy storage capacitor C0 is connected to two ends of the rectifier bridge and comprises an IC control chip, an NMOS tube N1, an NOMS tube N2, a capacitor C1, a capacitor C2, an HB pin, an HO pin and an HS pin, the grids of the NMOS tube N1 and the NOMS tube N2 are connected to two ends of the power resistor R1, the source and the drain of the NMOS tube N1 and the NOMS tube N2 are connected respectively, the N1 and the NOMS tube N2 are connected to the resistance value range of the power resistor N3510-10 omega, the power supply pin VCC of the IC control chip is connected to a power supply generated after the internal circuit normally works, the HS pin is connected to the source electrodes of the NMOS tube N1 and the NOMS tube N2, the HO pin is connected to the grid electrodes of the NMOS tube N1 and the NOMS tube N2, the HB pin is connected to the HS pin through a capacitor C1, the IC control chip comprises an undervoltage detection (UV) module, a Level Shift (LS) module, a Charge Pump (CP) module and a power drive (Drv) module, the charge pump module is used for charging the capacitor C1, the level shift module is used for shifting a high level signal output by the undervoltage detection module from a VCC voltage domain to a voltage domain between VHB and VHS, the undervoltage detection module is used for detecting the voltage of the VCC, the power drive module is used for enhancing the current driving capability of the high level signal in the voltage domain between the VHB and the VHS, capacitor C2 is connected to VCC power supply pin and GND pin, and capacitor C2 is the filter capacitor of power VCC.

The working principle is as follows: before the power supply equipment is started, the voltage value at two ends of an energy storage capacitor C0 is 0V, a power supply VCC generated by the power supply equipment is also equal to 0V, a control circuit IC does not work, a HO pin outputs 0V level relative to an HS pin, a power tube NMOS tube N1 and an NOMS tube N2 are cut off, at the moment, an AC alternating current power supply charges the capacitor C0 through a power resistor R1 and a rectifier bridge, the charged peak current is limited to Vac 1.414/R1 by a power resistor R1, the safe work of the rectifier bridge is ensured, the resistance value of the power resistor R1 is influenced very little by temperature, so the power supply equipment can be normally started under the low-temperature condition, when the voltage at two ends of the energy storage capacitor C0 is charged to be high enough, the power supply equipment starts to work, and generates a power supply voltage VCC, and the capacitor C2 is a filter capacitor of the power supply VCC; the charge pump CP starts to operate and charges the capacitor C1, the charging voltage is VHB-VHS, the specific voltage value is determined according to the gate control voltages of the NMOS transistor N1 and the NMOS transistor N2, and the voltages of the HS pin and the HB pin fluctuate along with the AC power supply voltage.

The voltage of VCC is detected by the undervoltage detection (UV) module, when the voltage of VCC is high enough, the undervoltage detection (UV) module outputs a high level signal, the Level Shift (LS) module shifts the high level signal from the VCC voltage domain to the voltage domain between VHB and VHS, the high level signal is output from the HO pin after the current driving capability is enhanced by the power driving (Drv) module, the voltage difference between the HO pin and the HS pin is approximately equal to the voltage difference between the HB pin and the HS pin, namely equal to the voltage difference generated by the charge pump, and the voltage difference between the HO pin and the HS pin turns on the power NMOS pipe N1 and the NMOS pipe N2.

After the NMOS tube N1 and the NMOS tube N2 are started, the NMOS tube N1 is connected with the on-resistance of the NMOS tube N2 in series and then connected with the power resistor R1 in parallel, and as the series on-resistance value 2Rdson of the NMOS tube N1 and the NMOS tube N2 is far smaller than the resistance value of the power resistor R1, the resistance value of the power resistor R1 can be ignored, the AC alternating current power supply supplies power to equipment through the very small on-resistance 2Rdson, and the loss of electric energy is greatly reduced.

In the description of the present invention, it should be noted that the terms "upper", "lower", "left", "right", "inner", "outer", etc. indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention; furthermore, unless expressly stated or limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, as they may be fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art will understand that various modifications can be made to the embodiments described in the foregoing embodiments, or some or all of the technical features of the embodiments can be equivalently replaced, and the modifications or the replacements do not make the essence of the corresponding technical solutions depart from the scope of the embodiments of the present invention.

Claims

1. A rectifier bridge starts the protective circuit, the said protective circuit includes rectifier bridge, energy storage capacitor C0 and power resistor R1, AC power supply will charge the capacitor C0 through power resistor R1 and rectifier bridge, power resistor R1 connects in series on the loop circuit between AC power supply and rectifier bridge, energy storage capacitor C0 connects at both ends of rectifier bridge, characterized by that, the protective circuit also includes IC control chip, NMOS pipe N1, NOMS pipe N2, capacitor C1, capacitor C2, HB base pin, HO base pin and HS base pin.

2. The rectifier bridge starting protection circuit as claimed in claim 1, wherein the gates of the NMOS transistor N1 and the NOMS transistor N2 are connected to two ends of the power resistor R1, and the sources and drains of the NMOS transistor N1 and the NOMS transistor N2 are connected to each other.

3. The rectifier bridge start-up protection circuit of claim 2, wherein the IC control chip comprises an under-voltage detection module, a level shift module, a charge pump module, and a power driving module, the charge pump module is configured to charge the capacitor C1, the level shift module is configured to shift a high-level signal output by the under-voltage detection module from a VCC voltage domain to a voltage domain between VHB and VHS, the under-voltage detection module is configured to detect a voltage of VCC, and the power driving module is configured to enhance a current driving capability of the high-level signal in the voltage domain between VHB and VHS.

4. The protection circuit of claim 3, wherein the VCC power supply pin of the IC control chip is connected to the internal circuit, the HS pin is connected to the sources of NMOS transistor N1 and NOMS transistor N2, the HO pin is connected to the gates of NMOS transistor N1 and NOMS transistor N2, and the HB pin is connected to the HS pin through capacitor C1.

5. The rectifier bridge starting protection circuit according to claim 4, wherein the resistance value of the power resistor R1 is in a range of 10 Ω -10K Ω.

6. The rectifier bridge start-up protection circuit of claim 5, wherein the on-resistance value of the NMOS transistor N1 and the NOMS transistor N2 is in a range of 5m Ω -10 Ω.

7. The rectifier bridge start-up protection circuit of claim 6, wherein the voltage of the HS pin and the HB pin fluctuates with the AC power supply voltage.

8. The protection circuit of claim 7, wherein the capacitor C2 is connected to a VCC power supply pin and a GND pin, and the capacitor C2 is a filter capacitor of the power supply VCC.