CN211321212U

CN211321212U - Converter pre-charging loop with burning loss prevention function

Info

Publication number: CN211321212U
Application number: CN202020319220.1U
Authority: CN
Inventors: 王超
Original assignee: Lexing Electric Wuxi Co ltd
Current assignee: Lexing Electric Wuxi Co ltd
Priority date: 2020-03-13
Filing date: 2020-03-13
Publication date: 2020-08-21
Anticipated expiration: 2030-03-13

Abstract

The utility model discloses a converter is charging circuit in advance with prevent scaling loss function relates to converter technical field, and this is charging circuit in advance includes rectifier circuit and IGBT inverter circuit, and rectifier circuit includes six diodes, NTC charging resistor, relay, first electric capacity, second electric capacity, first resistance and second resistance, and the relay connects in parallel at NTC charging resistor's both ends, and IGBT inverter circuit includes six IGBT modules. Because the NTC charging resistor is a negative temperature coefficient resistor, the resistance value of the NTC charging resistor is reduced along with the rise of the temperature, by utilizing the temperature characteristic, even if the NTC charging resistor is continuously connected into the main loop by the misoperation of the relay, the resistance value is immediately reduced after the temperature of the NTC charging resistor rises, on one hand, the heat productivity of the resistor is reduced, the burning loss of a PCB light plate and surrounding components caused by overhigh temperature can not be caused, on the other hand, the limitation of the resistor on the current is reduced after the resistance value of the NTC resistor is reduced, and the loading capacity of the product can not be greatly influenced.

Description

Converter pre-charging loop with burning loss prevention function

Technical Field

The utility model belongs to the technical field of the converter technique and specifically relates to a converter is charging circuit in advance with prevent scaling loss function.

Background

In the prior art, a winding resistor made of cement is generally adopted as a charging resistor of a pre-charging loop of a frequency converter and used for protecting a rectifier bridge in the initial stage of power-on, and because a main capacitor has no voltage, a current peak formed by a large voltage difference at the moment of power-on exceeds the current of a diode of the rectifier bridge, so that the diode is burnt. The cement winding resistor is not easy to damage due to strong temperature resistance and can bear high temperature. When the voltage of the main capacitor reaches 460V, the relay connected in parallel to the cement winding resistor is closed, and the cement winding resistor is bypassed. Otherwise, the cement winding resistor can continuously limit the current in the main loop, and the loading capacity of the frequency converter is influenced.

However, in practical application, due to signal transmission interference in an industrial field, or due to the problems of corrosion of relay contacts, quality of the relay and the like caused by the service life of the relay and field corrosive gas, it is difficult to avoid the situation that the contacts are in poor contact when the relay malfunctions or is sucked. Use cement wire resistor under relay malfunction or contact failure's the condition, cement wire resistor can continuously generate heat, leads to the worn-out fur carbonization around the cement wire resistor, and other devices near cement wire resistor also can appear melting and scaling loss because the heat is too high. The frequency converter product can not carry out self protection under this kind of condition, only continuous generating heat causes cement wire winding resistance to burn and decreases, and the frequency converter major loop is because the power supply interruption stop work, can only be maintained by the discovery of user after finally waiting to mechanical equipment stop work.

SUMMERY OF THE UTILITY MODEL

In view of the above problems and technical needs, the present applicant has proposed an inverter pre-charge circuit with burn-out prevention function, which employs an NTC charging resistor instead of a cement winding resistor as a charging resistor of the inverter pre-charge circuit, and since the resistance of the NTC charging resistor decreases with an increase in temperature, even if the NTC charging resistor is continuously connected to a main circuit, the burn-out of surrounding devices and the main circuit is not caused.

The technical scheme of the utility model as follows:

a pre-charging circuit of a frequency converter with an anti-burning function comprises a rectifying circuit and an IGBT (insulated gate bipolar transistor) inverter circuit, wherein the rectifying circuit comprises six diodes, an NTC (negative temperature coefficient) charging resistor, a relay, a first capacitor, a second capacitor, a first resistor and a second resistor;

one end of an NTC charging resistor is connected with the common end of the cathode of a first diode, the cathode of a second diode and the cathode of a third diode, the other end of the NTC charging resistor is connected with a second capacitor through a first capacitor, the other end of the NTC charging resistor is also connected with the second resistor through the first resistor, the NTC charging resistor is a negative temperature coefficient resistor, the resistance value of the NTC charging resistor is reduced along with the rise of the temperature, the first resistor is connected in parallel with the two ends of the first capacitor, the second resistor is connected in parallel with the two ends of the second capacitor, the common end of the second capacitor and the second resistor is connected with the common end of the anode of a fourth diode, the anode of a fifth diode and the anode of a sixth diode, the anode of the first diode is connected with the cathode of the fourth diode, the anode of the second diode is connected with the cathode of the fifth diode, the anode of the third diode is connected with the cathode of the sixth diode, the three-phase alternating current power supply is respectively and correspondingly connected with the common ends of two diodes of each diode loop, the relay is connected in parallel with two ends of the NTC charging resistor, one end of the first resistor is respectively connected with the collector of the first IGBT module, the collector of the second IGBT module and the collector of the third IGBT module, the emitter of the first IGBT module is connected with the collector of the fourth IGBT module, the emitter of the second IGBT module is connected with the collector of the fifth IGBT module, the emitter of the third IGBT module is connected with the collector of the sixth IGBT module, the common ends of the emitter of the fourth IGBT module, the emitter of the fifth IGBT module and the emitter of the sixth IGBT module are connected with the common ends of the second capacitor and the second resistor, the gate pole of each IGBT module is connected with the CPU, the collector of each IGBT module is also connected with the cathode of the diode, the emitter of each IGBT module is also connected with the anode of the diode, and, and the common ends of the two IGBT modules of each IGBT loop respectively correspond to the three-phase alternating current power supply after frequency conversion.

The technical scheme is that the NTC charging resistor is realized based on a DSC-10D13MSFC model.

The utility model has the beneficial technical effects that:

the application discloses a converter pre-charge circuit with prevent scaling loss function, it has adopted NTC charging resistor to replace cement wire winding resistance as the charging resistor of converter pre-charge circuit, because NTC charging resistor is the resistance of a negative temperature coefficient, its resistance reduces along with the rising of temperature, utilize this temperature characteristic, even relay malfunction makes NTC charging resistor continuously insert the major loop, after NTC charging resistor temperature rose, the resistance reduces immediately, on the one hand the calorific capacity of resistance itself has been reduced, can not make PCB worn-out fur and surrounding components and parts lead to the scaling loss because the high temperature, on the other hand after NTC resistance reduces, itself descends to the restriction of electric current, the area load ability of product can not receive great influence.

Drawings

Fig. 1 is a circuit diagram of a frequency converter pre-charging loop with a burnout prevention function disclosed in the present application.

Detailed Description

The following describes the embodiments of the present invention with reference to the accompanying drawings.

The application discloses converter pre-charge circuit with prevent scaling loss function, its circuit diagram is shown in fig. 1, and the pre-charge circuit includes rectifier circuit and IGBT inverter circuit, and rectifier circuit includes six diodes, NTC charging resistor R, relay K, first electric capacity C1, second electric capacity C2, first resistance R1 and second resistance R2, and IGBT inverter circuit includes six IGBT modules.

In the present application, the NTC charging resistor R is implemented based on a DSC-10D13MSFC model, which has a resistance of 10 Ω ± 20% at 25 ℃ and a power of 5.12W, and is a negative temperature coefficient resistor whose resistance decreases with increasing temperature. Specifically, one end of an NTC charging resistor R is connected to a common terminal of a cathode of a first diode D1, a cathode of a second diode D2 and a cathode of a third diode D3, the other end of the NTC charging resistor R is connected to a second capacitor C2 through a first capacitor C1, the other end of the NTC charging resistor R is further connected to a second resistor R2 through a first resistor R1, the first resistor R1 is connected in parallel to both ends of the first capacitor C1, a second resistor R2 is connected in parallel to both ends of the second capacitor C2, a common terminal of the second capacitor C2 and the second resistor R2 is connected to an anode of a fourth diode D4, an anode of the fifth diode D5 and a common terminal of an anode of the sixth diode D6, an anode of the first diode is connected to a cathode of the fourth diode, an anode of the second diode is connected to a cathode of the fifth diode, anodes of the third diode is connected to a cathode of the sixth diode, six diodes form three-phase alternating current power supplies, and the two common terminals of each three-phase alternating current power supplies are, in the application, the three-phase alternating current power supply adopts three-phase 50Hz power frequency alternating current. Optionally, an R pin of the three-phase ac power supply is connected to a common terminal of the first diode D1 and the fourth diode D4, an S pin of the three-phase ac power supply is connected to a common terminal of the second diode D2 and the fifth diode D5, and a T pin of the three-phase ac power supply is connected to a common terminal of the third diode D3 and the sixth diode D6. The relay K is connected in parallel at two ends of the NTC charging resistor R, one end of the first resistor R1 is respectively connected with the collector of the first IGBT module V1, the collector of the second IGBT module V2 and the collector of the third IGBT module V3, the emitter of the first IGBT module V1 is connected with the collector of the fourth IGBT module V4, the emitter of the second IGBT module V2 is connected with the collector of the fifth IGBT module V5, the emitter of the third IGBT module V3 is connected with the collector of the sixth IGBT module V6, the emitter of the fourth IGBT module V4, the common ends of the emitter of the fifth IGBT module V5 and the emitter of the sixth IGBT module V6 are connected with the common ends of a second capacitor C2 and a second resistor R2, the gate of each IGBT module is connected with a CPU, the collector of each IGBT module is also connected with the cathode of a diode, the emitter of each IGBT module is also connected with the anode of the diode, the six IGBT modules form three IGBT loops, and the common ends of the two IGBT modules of each IGBT loop respectively correspondingly output a three-phase alternating current power supply after frequency conversion. Optionally, a U pin of the frequency-converted three-phase ac power supply is connected to common terminals of the first IGBT module V1 and the fourth IGBT module V4, a V pin of the frequency-converted three-phase ac power supply is connected to common terminals of the second IGBT module V2 and the fifth IGBT module V5, and a W pin of the frequency-converted three-phase ac power supply is connected to common terminals of the third IGBT module V3 and the sixth IGBT module V6.

The utility model discloses a converter precharge circuit's with prevent scaling loss function input inserts three-phase 50Hz power frequency alternating current, and the uncontrollable rectifier circuit that six diodes are constituteed is rectified three-phase alternating current into pulsatory direct current, then becomes frequency and amplitude adjustable alternating current through the IGBT inverter circuit contravariant that six IGBT modules are constituteed to export for the load through U, V, W three-phase. The first capacitor C1 and the second capacitor C2 are main capacitors and play a role in filtering and storing energy, and the first resistor R1 and the second resistor R2 are voltage-sharing resistors and are used for sharing voltage of the first capacitor C1 and the second capacitor C2. Because the two main capacitors of the first capacitor C1 and the second capacitor C2 have no voltage at two ends before being electrified, a large current is generated at the electrifying moment, the NTC charging resistor R plays a role in limiting the current at the electrifying moment, and protects the six diodes from being burnt by the large current, and when the voltage of the main capacitors reaches 460V, the relay K connected in parallel with the NTC charging resistor R attracts to bypass the NTC charging resistor R.

This precharge return circuit has adopted NTC charging resistor to replace cement wire winding resistance as the charging resistor of converter precharge return circuit, because NTC charging resistor is the resistance of a negative temperature coefficient, its resistance reduces along with the rising of temperature, utilize this temperature characteristic, even relay malfunction makes NTC charging resistor continuously insert the main loop, after NTC charging resistor temperature rose, the resistance reduces immediately, on the one hand reduced the calorific capacity of resistance itself, can not make PCB worn-out fur and surrounding components and parts lead to the scaling loss because the temperature is too high, on the other hand after NTC resistance reduces, the restriction to the electric current of itself descends, the loading capacity of product can not receive great influence. If the load used by the end user equipment is small, the operation of the equipment is basically not influenced, and the frequency converter can continuously operate under the condition that the NTC charging resistor is connected. If the load dragged by the user equipment is large, the problem of insufficient energy supply caused by the access of the NTC charging resistor can cause the situation that the output torque of the frequency converter is insufficient, and a user can find the problem that the relay K is not attracted or the contact of the contact is poor according to the phenomenon.

What has been described above is only a preferred embodiment of the present application, and the present invention is not limited to the above embodiments. It is to be understood that other modifications and variations directly derivable or suggested by those skilled in the art without departing from the spirit and scope of the present invention are to be considered as included within the scope of the present invention.

Claims

1. The pre-charging circuit of the frequency converter with the burning loss prevention function is characterized by comprising a rectifying circuit and an IGBT (insulated gate bipolar transistor) inverter circuit, wherein the rectifying circuit comprises six diodes, an NTC charging resistor, a relay, a first capacitor, a second capacitor, a first resistor and a second resistor, and the IGBT inverter circuit comprises six IGBT modules;

one end of the NTC charging resistor is connected with a common end of a first diode cathode, a second diode cathode and a third diode cathode, the other end of the NTC charging resistor is connected with the second capacitor through the first capacitor, the other end of the NTC charging resistor is also connected with the second resistor through the first resistor, the NTC charging resistor is a negative temperature coefficient resistor, the resistance value of the NTC charging resistor is reduced along with the rise of the temperature, the first resistor is connected in parallel with two ends of the first capacitor, the second resistor is connected in parallel with two ends of the second capacitor, the common end of the second capacitor and the second resistor is connected with the common end of a fourth diode anode, a fifth diode anode and a sixth diode anode, the anode of the first diode is connected with the cathode of the fourth diode, and the anode of the second diode is connected with the cathode of the fifth diode, the anode of the third diode is connected with the cathode of the sixth diode, the six diodes form three diode loops, a three-phase alternating current power supply is correspondingly connected with the common end of two diodes of each diode loop respectively, the relay is connected in parallel with two ends of the NTC charging resistor, one end of the first resistor is connected with the collector of the first IGBT module, the collector of the second IGBT module and the collector of the third IGBT module respectively, the emitter of the first IGBT module is connected with the collector of the fourth IGBT module, the emitter of the second IGBT module is connected with the collector of the fifth IGBT module, the emitter of the third IGBT module is connected with the collector of the sixth IGBT module, and the common ends of the emitter of the fourth IGBT module, the emitter of the fifth IGBT module and the emitter of the sixth IGBT module are connected with the common end of the second capacitor and the second resistor, the gate pole of each IGBT module is connected with the CPU, the collector of each IGBT module is further connected with the cathode of a diode, the emitter of each IGBT module is further connected with the anode of a diode, the six IGBT modules form three IGBT loops, and the common ends of the two IGBT modules of each IGBT loop respectively correspond to the three-phase alternating current power supply after frequency conversion.

2. The inverter pre-charging loop with burning loss prevention function according to claim 1, wherein the NTC charging resistor is implemented based on DSC-10D13MSFC model.