CN101694938A - Surging current suppression method - Google Patents

Abstract

The invention discloses a surging current suppression method, which belongs to the application technology of device power ports. The method is formed as follows: at least one surging current suppression circuit is in series connection between an electric equipment power port and a commercial power, and large current impacts produced when electric equipment is started routinely can be effectively suppressed by adjusting impedance of an electric equipment power terminal through the surging current suppression circuit. The surging current suppression method can simultaneously guarantee power supply quality of a power network, avoid producing severe electromagnetic interference and not affect other properties of equipment while effectively suppress surging current.

Description

A kind of surge current suppression method

technical field

The invention relates to the application technology of the power supply interface of equipment, in particular to a surge current suppression method.

Background technique

Inrush current is the peak current that flows into the power supply device at the moment the power is turned on. The surge occurs for a very short time, probably at the microsecond level, and the magnitude of the current is more than twice the normal value. This peak current is much greater than the steady-state input current due to the rapid charging of the input filter capacitor. If the surge current exceeds the capacity of the device, the device will be completely destroyed or its life will be greatly reduced. The cumulative effect of multiple small surges can also cause semiconductor device performance degradation, equipment failure and shortened lifetime, resulting in decreased productivity. Moreover, the surge current will destroy the power supply quality of the grid, not only generate serious electromagnetic interference, but also affect other equipment connected to the grid.

Contents of the invention

The technical task of the present invention is to provide a surge current suppression method.

Technical task of the present invention is realized in the following way, and this method is as follows:

At least one inrush current suppression circuit is connected in series between the power supply port of the electrical equipment and the mains, and the impedance of the power supply terminal of the electrical equipment is adjusted through the surge current suppression circuit, effectively suppressing the large current impact generated by the normal startup of the electrical equipment.

The surge current suppressing circuit includes a thermistor 1, a relay 1 and a triode 1, the thermistor 1 and the relay 1 are connected in parallel, and one end is connected to the rectifier bridge, and the other end is respectively connected to the electrical equipment and a low-power auxiliary power supply. The power auxiliary power supply is connected with the relay driving circuit, the relay driving circuit is connected with the relay one, and the circuit connected between the relay driving circuit and the relay one is connected with the transistor one for improving the current driving ability.

A static discharge resistor 1 is connected to the circuit between the triode 1 and the electrical equipment, and a driving resistor 1 is connected to the circuit between the triode 1 and the relay driving circuit.

The relay one is provided with a clamping diode one for clamping the reverse voltage and protecting other devices from being damaged.

In the circuit: the rectifier bridge is used to rectify AC mains electricity into DC; the thermistor is a thermistor with a large resistance and positive temperature coefficient; the relay is in an open circuit state when it is not driven, and it is closed after being driven; the clamping diode is used To clamp the reverse voltage generated by the driving winding when the relay is in state transition, to protect other devices from damage; the triode is used to improve the current driving capability and ensure the good on-off of the relay; the low-power auxiliary power supply is a non-isolated power supply, Input and output common ground.

The surge current suppressing method of the present invention effectively suppresses the surge current while ensuring the power supply quality of the grid, avoiding serious electromagnetic interference, and not affecting other performances of the equipment. The surge current suppression circuit has reasonable design, convenient use and low installation cost.

Description of drawings

Accompanying drawing 1 is a schematic diagram of the use of the surge current suppression circuit;

Accompanying drawing 2 is a schematic diagram of using two stages of inrush current suppression circuit in series.

In the figure: A1, inrush current suppression circuit 1, A2, inrush current suppression circuit 2, D1, rectifier bridge, RT, thermistor 1, J1, relay 1, D2, clamping diode 1, R1, drive resistor 1 , R2, static discharge resistor 1, Q1, transistor 1, M1, electrical equipment, M2, low-power auxiliary power supply, M3, relay drive circuit, RT1, thermistor 2, J2, relay 2, D3, clamping diode 2 , R3, drive resistor two, R4, static discharge resistor two, Q2, transistor two.

Detailed ways

Example 1:

A surge current suppression circuit is connected in series between the power supply port of the electrical equipment and the mains, and the impedance of the power supply terminal of the electrical equipment is adjusted through the surge current suppression circuit, effectively suppressing the large current impact generated by the normal startup of the electrical equipment.

The circuit connection is as follows: the inrush current suppression circuit A1 includes a thermistor-RT, a relay-J1 and a transistor-Q1. After the thermistor-RT and relay-J1 are connected in parallel, one end is connected to the rectifier bridge D1, and the other end is respectively connected to the electrical equipment M1 is connected to the low-power auxiliary power supply M2, the low-power auxiliary power supply M2 is connected to the relay drive circuit M3, the relay drive circuit M3 is connected to the relay-J1, and the circuit connected between the relay drive circuit M3 and the relay-J1 is used to increase the current Transistor-Q1 of driving capability; static discharge resistor-R2 is connected to the circuit between triode-Q1 and electrical equipment M1, and driving resistor-R1 is connected to the circuit between triode-Q1 and relay drive circuit M3.

The relay-J1 is provided with a clamping diode-D2 for clamping the reverse voltage and protecting other components from being damaged.

The circuit operation process is:

The electrical equipment M1 is started, the mains power is connected to the circuit, and rectified into DC by the rectifier bridge D1. At this time, the relay-J1 is in the disconnected state, and the electrical equipment M1 can only be powered through the thermistor-RT, and the circuit is in a high-impedance state. , only a small current flows through the thermistor-RT to supply power for the electrical equipment M1 and the low-power auxiliary power supply M2, the power input filter capacitor of the electrical equipment M1 is slowly charged, the surge current is well suppressed, and the low-power auxiliary power supply M2 supplies power to the relay drive circuit M3 through the output voltage Vcc of the low-power auxiliary power supply. After a delay for a period of time, the output drive signal is sent to the transistor-Q1, and the transistor-Q1 is turned on. The output voltage Vcc of the low-power auxiliary power supply is provided for the drive winding of the relay-J1. Current, relay one J1 pulls in, the thermistor one RT is short-circuited, the circuit is in a low impedance state, and the current flows through relay one J1 to supply the electrical equipment M1, because the power input filter capacitor of the electrical equipment M1 has been pre-charged, at this time No large inrush current will be generated. The on-resistance of the relay-J1 is much smaller than that of the thermistor-RT, which basically belongs to the short-circuit state and will not affect the efficiency of the steady-state operation of the electrical equipment M1. With the normal operation of the equipment, the temperature inside the equipment rises, and the resistance value of the thermistor RT will increase, showing a higher impedance, so that it can ensure that all the power supply current is provided to the electrical equipment M1 through the relay J1, which is stable for the equipment. There is no impact on operating efficiency.

Example 2:

Two inrush current suppression circuits are connected in series between the power supply port of the electrical equipment and the mains, and the impedance of the power supply terminal of the electrical equipment is adjusted through the surge current suppression circuit, effectively suppressing the large current impact generated by the normal startup of the electrical equipment.

The circuit connection is as follows: the surge current suppression circuit A1 and the surge current suppression circuit A2 are connected in series between the rectifier bridge D1 and the electrical equipment M1; the surge current suppression circuit A1 includes a thermistor-RT, a relay-J1 and a transistor-Q1 , the thermistor-RT and relay-J1 are connected in parallel, and one end is connected to the rectifier bridge D1, and the other end is connected to the surge current suppression circuit A2; the collector of the triode-Q1 used to improve the current driving capability is connected to the relay-J1, and the emitter Grounded, the base is connected to the surge current suppression circuit A2, and the connected circuit is respectively connected with a driving resistor R1 and a static discharge resistor R2; the relay J1 is set to clamp the reverse voltage to protect other devices from Damaged clamping diode - D2.

The surge current suppression circuit A2 includes thermistor 2 RT1, relay 2 J2 and transistor 2 Q2. After the thermistor 2 RT1 and relay 2 J2 are connected in parallel, one end is connected to the surge current suppression circuit A1, and the other end is respectively connected to the electrical equipment M1 It is connected with the low-power auxiliary power supply M2, the low-power auxiliary power supply M2 is connected with the relay drive circuit M3, and the relay drive circuit M3 is respectively connected with the relay one J1 and the relay two J2; J2 is connected, the emitter is grounded, the base is connected to the electrical equipment M1 and the relay driving circuit M3 respectively, the static discharge resistor R4 is connected to the circuit where the base is connected to the electrical equipment M1, and the base is connected to the relay driving circuit M3 The circuit is connected with a driving resistor R3; the relay J2 is provided with a clamping diode D3 for clamping the reverse voltage and protecting other components from damage.

The circuit operation process is as in embodiment 1.

Claims (4)

1. A surge current suppression method is characterized in that at least one surge current suppression circuit is connected in series between the power supply port of the electric device and the mains, and the impedance of the power supply terminal of the electric device is adjusted by the surge current suppression circuit to effectively suppress The large current impact generated by the normal start-up of electrical equipment. 2. The inrush current suppression method according to claim 1, wherein the inrush current suppression circuit comprises a thermistor one, a relay one and a triode one, and one end of the thermistor one and a relay one are connected in parallel with the rectifier Bridge connection, the other end is respectively connected with the electrical equipment and the low-power auxiliary power supply, the low-power auxiliary power supply is connected with the relay drive circuit, the relay drive circuit is connected with the relay one, and the circuit connected between the relay drive circuit and the relay one is used for Transistor 1 with improved current drive capability. 3. The surge current suppression method according to claim 2, characterized in that the circuit between the triode one and the electrical equipment is connected with a static discharge resistor one, and the circuit between the triode one and the relay drive circuit connected with drive resistor one. 4. The surge current suppression method according to claim 2, characterized in that said relay one is provided with clamping diode one for clamping the reverse voltage and protecting other devices from being damaged.

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