CN213602554U

CN213602554U - Improved circuit for enhancing starting capability of inverter

Info

Publication number: CN213602554U
Application number: CN202021904498.1U
Authority: CN
Inventors: 朱德华; 刘瑜; 龚士权; 陈功义
Original assignee: New Focus Lighting and Power Technology Shanghai Co Ltd
Current assignee: New Focus Lighting and Power Technology Shanghai Co Ltd
Priority date: 2020-09-03
Filing date: 2020-09-03
Publication date: 2021-07-02
Anticipated expiration: 2030-09-03

Abstract

This technical scheme provides an improvement circuit of inverter reinforcing startability, through the mode that changes inverter short-circuit current detection, change full-wave detection into by the full-bridge, increase a branch road in addition in the short-circuit protection circuit of inverter and be used for the detection of short-circuit current direction to judge the branch road of taking place the short circuit, and then can effectually open the current flow direction of full-bridge in turn, guarantee that the MOS pipe can undertake heavy current impact in turn, when reducing components and parts production of heat, promoted the startability of load.

Description

Improved circuit for enhancing starting capability of inverter

Technical Field

The utility model relates to an inverter field especially relates to an improvement circuit of dc-to-ac converter reinforcing startability.

Background

Inverters are widely used in life as a converter for converting direct current electric energy (batteries, storage batteries) into constant frequency, constant voltage or frequency and voltage regulation alternating current. The load on the market is various, for example, the instantaneous power when the inductive load such as an air conditioner, a refrigerator and the like is started can reach 3-5 times of the rated power, and for example, the starting characteristic of the rectifying load such as a high-frequency welding machine is close to a short circuit, so that the inverter has a short circuit protection function in order to protect the inverter from being damaged when being used on a large impact load.

As shown in the circuit topology of the conventional inverter shown in fig. 1, only one branch of the protection circuit generates a short-circuit current detection signal, and the direction of the short-circuit current cannot be detected. The MOS tube in the bridge inverter circuit is always impacted by short-circuit current to reduce the impact resistance, and if the impact of the short-circuit current on the device is reduced by reducing the set short-circuit current value, the starting capability of the corresponding inverter is weakened.

Disclosure of Invention

In view of the above problems in the prior art, an improved circuit for enhancing the starting capability of an inverter is provided, and the specific technical solution is as follows:

the protection circuit is connected with a load through a current transformer and comprises a first output end and a second output end;

the bridge inverter circuit is connected with the load;

the microcontroller is connected with the bridge type inverter circuit and comprises a first sampling feedback pin and a second sampling feedback pin, the first output end is connected with the first sampling feedback pin, and the second output end is connected with the second sampling feedback pin.

Preferably, a first pulse width generating pin and a second pulse width generating pin of the microcontroller are respectively connected to a gate of a first MOS transistor and a gate of a second MOS transistor in the bridge inverter circuit, and a fourth pulse width generating pin and a third pulse width generating pin of the microcontroller are respectively connected to a gate of a fourth MOS transistor and a gate of a third MOS transistor in the bridge inverter circuit.

Preferably, the source of the second MOS transistor and the source of the fourth MOS transistor in the bridge inverter circuit are grounded, and the drain of the first MOS transistor and the drain of the third MOS transistor are connected to a dc power supply.

Preferably, a first node is arranged between the source electrode of the first MOS transistor and the drain electrode of the second MOS transistor, a second node is arranged between the source electrode of the third MOS transistor and the drain electrode of the fourth MOS transistor, and the current transformer and the load are connected between the first node and the second node.

Preferably, the protection circuit is provided with a first diode and a second diode, an output end of the first diode is connected with the first output end, and an output end of the second diode is connected with the second output end.

Preferably, the lower end of the secondary side winding of the current transformer is connected with the input end of the first diode, and the upper end of the secondary side winding of the current transformer is connected with the input end of the second diode.

Preferably, a third node is further arranged in the middle of the secondary side winding of the current transformer, and the third node is grounded.

Preferably, the protection circuit further includes a first resistor and a second resistor, the first resistor is connected between the output terminal of the second diode and the third node, and the second resistor is connected between the output terminal of the first diode and the third node.

The technical scheme has the following advantages or beneficial effects:

this technical scheme provides an improvement circuit of inverter reinforcing start-up ability, through the mode that changes inverter short-circuit current detection, change full-wave detection into by the full-bridge, increase a branch road in addition in the protection circuit of inverter and be used for the detection of short-circuit current direction to judge the branch road that takes place the short circuit, and then can effectually open the current flow direction of full-bridge in turn, guarantee that the MOS pipe can undertake heavy current impact in turn, promoted the start-up ability of load when reducing components and parts production of heat.

Drawings

FIG. 1 is a circuit topology diagram of a conventional inverter;

fig. 2 is a topology diagram of an improved inverter circuit.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by a person of ordinary skill in the art without creative efforts belong to the protection scope of the present invention.

It should be noted that, in the present invention, the embodiments and features of the embodiments may be combined with each other without conflict.

The present invention will be further described with reference to the accompanying drawings and specific embodiments, but the present invention is not limited thereto.

In view of the above problems in the prior art, there is provided an improved circuit for enhancing the starting capability of an inverter, as shown in fig. 2, including:

the protection circuit is connected with a load RL through a current transformer T1 and comprises a first output end and a second output end;

a bridge inverter circuit connected to the load RL;

and the microcontroller U1 is connected with the bridge inverter circuit, the microcontroller U1 comprises a first sampling feedback pin 1 and a second sampling feedback pin 2, a first output end is connected with the first sampling feedback pin 1, and a second output end is connected with the second sampling feedback pin 2.

A first pulse width generating pin 6 of the microcontroller U1 generates a first pulse width modulation signal DR1, a second pulse width generating pin 5 of the microcontroller U1 generates a second pulse width modulation signal DR2, a third pulse width generating pin 4 of the pulse width microcontroller U1 generates a third pulse width modulation signal DR3, and a fourth pulse width generating pin 3 of the microcontroller U1 generates a fourth pulse width modulation signal DR 4.

As a preferred embodiment, the first pulse width generating pin 6 and the second pulse width generating pin 5 of the microcontroller U1 are respectively connected to the gate of a first MOS transistor M1 and the gate of a second MOS transistor M2 in the bridge inverter circuit, and the fourth pulse width generating pin 3 and the third pulse width generating pin 4 of the microcontroller U1 are respectively connected to the gate of a fourth MOS transistor M4 and the gate of a third MOS transistor M3 in the bridge inverter circuit; the pulse width modulation signals DR 1-DR 4 generated by the microcontroller U1 respectively drive the first MOS transistor M1, the second MOS transistor M2, the fourth MOS transistor M4 and the third MOS transistor M3 to alternately work to provide alternating current output for the load RL.

In a preferred embodiment, the source of the second MOS transistor M2 and the source of the fourth MOS transistor M4 in the bridge inverter circuit are grounded, and the drain of the first MOS transistor M1 and the drain of the third MOS transistor M3 are connected to a dc power supply.

In a preferred embodiment, a first node is disposed between the source of the first MOS transistor M1 and the drain of the second MOS transistor M2, a second node is disposed between the source of the third MOS transistor M3 and the drain of the fourth MOS transistor M4, and the current transformer T1 and the load RL are connected between the first node and the second node.

In a preferred embodiment, the protection circuit has a first diode D1 and a second diode D2, the output terminal of the first diode D1 is connected to the first output terminal, and the output terminal of the second diode D2 is connected to the second output terminal.

In a preferred embodiment, the lower end of the secondary winding of the current transformer T1 in the protection circuit is connected to the input terminal of the first diode D1, and the upper end of the secondary winding of the current transformer T1 is connected to the input terminal of the second diode D2.

In a preferred embodiment, a third node is further disposed in the middle of the secondary winding of the current transformer T1, and the third node is grounded.

In a preferred embodiment, the protection circuit further includes a first resistor R1 and a second resistor R2, the first resistor R1 is connected between the output terminal of the second diode D2 and the third node, and the second resistor R2 is connected between the output terminal of the first diode D1 and the third node.

When the second pwm signal DR2 and the fourth pwm signal DR4 are effective values, the second MOS transistor M2 and the third MOS transistor M3 are turned on, assuming that a large current flows through the load RL at this time, the current in the protection circuit forms a short-circuit detection signal IS1 through the current transformer T1, the second diode D2 and the first resistor R1, the microcontroller U1 reads the short-circuit detection signal IS1 and stops sending the pwm signals DR 1-DR 4, when the short-circuit detection signal IS1 disappears, the microcontroller U1 turns on and sends only the first pwm signal DR1 and the third pwm signal DR3 to turn on the first MOS transistor M1 and the fourth MOS transistor M4, and at this time, the load of the RL does not decrease. Meanwhile, a short-circuit detection signal IS2 in the opposite direction IS formed on the other branch of the protection circuit, the microcontroller U1 stops sending the pulse width modulation signals DR 1-DR 4 after reading the short-circuit detection signal IS2 in the opposite direction, and when the short-circuit detection signal IS2 in the opposite direction disappears, the microcontroller U1 generates only the second pulse width modulation signal DR2 and the fourth pulse width modulation signal DR4 to enable the second MOS transistor M2 and the third MOS transistor M3 to be conducted, and the cycle IS repeated, so that the first MOS transistor M1, the third MOS transistor M3, the second MOS transistor M2 and the fourth MOS transistor M4 can alternately rest for one period to reduce the heat generation amount of the protection circuit.

In conclusion, according to the technical scheme, the mode of detecting the short-circuit current of the inverter is changed from the full-bridge mode to the full-wave mode, and the branch circuit is added in the protection circuit of the inverter and used for detecting the direction of the short-circuit current, so that the branch circuit with the short circuit is judged, the current flow direction of the full-bridge can be effectively and alternately switched on, the MOS tube can alternately bear the large-current impact, the heat generated by components is reduced, and the starting capability of the load is improved.

The above description is only an example of the preferred embodiment of the present invention, and not intended to limit the scope of the present invention, and those skilled in the art should be able to realize the equivalent alternatives and obvious variations of the present invention.

Claims

1. An improved circuit for enhancing starting capability of an inverter, comprising:

the bridge inverter circuit is connected with the load;

2. The improved circuit for enhancing startup capability of inverter of claim 1, wherein a first pulse width generating pin and a second pulse width generating pin of said microcontroller are connected to the gate of a first MOS transistor and the gate of a second MOS transistor of said bridge inverter circuit, respectively, and a fourth pulse width generating pin and a third pulse width generating pin of said microcontroller are connected to the gate of a fourth MOS transistor and the gate of a third MOS transistor of said bridge inverter circuit, respectively.

3. The improved circuit for enhancing starting capability of inverter according to claim 2, characterized in that the source of the second MOS transistor and the source of the fourth MOS transistor in the bridge inverter circuit are grounded, and the drain of the first MOS transistor and the drain of the third MOS transistor are connected to a dc power supply.

4. The improved circuit for enhancing startup capability of inverter according to claim 3, wherein a first node is disposed between the source of the first MOS transistor and the drain of the second MOS transistor, a second node is disposed between the source of the third MOS transistor and the drain of the fourth MOS transistor, and the current transformer and the load are connected between the first node and the second node.

5. The improved circuit for enhancing startup capability of an inverter of claim 1, wherein said protection circuit is provided with a first diode and a second diode, an output terminal of said first diode is connected to said first output terminal, and an output terminal of said second diode is connected to said second output terminal.

6. The improved circuit for enhancing starting capability of inverter as claimed in claim 5, wherein the lower end of the secondary winding of said current transformer is connected to the input terminal of said first diode, and the upper end of the secondary winding of said current transformer is connected to the input terminal of said second diode.

7. The improved circuit for enhancing starting capability of inverter as claimed in claim 6, wherein a third node is further disposed between the secondary windings of said current transformer, and said third node is grounded.

8. The improved inverter starting capability improvement circuit according to claim 7, wherein said protection circuit further comprises a first resistor and a second resistor, said first resistor is connected between the output terminal of said second diode and said third node, and said second resistor is connected between the output terminal of said first diode and said third node.