CN212012457U

CN212012457U - Driving circuit based on frequency converter

Info

Publication number: CN212012457U
Application number: CN202021074226.3U
Authority: CN
Inventors: 肖至恢
Original assignee: Shenzhen Moter Driver Technology Co ltd
Current assignee: Shenzhen Moter Driver Technology Co ltd
Priority date: 2020-06-09
Filing date: 2020-06-09
Publication date: 2020-11-24
Anticipated expiration: 2030-06-09

Abstract

The utility model relates to a converter technical field discloses a drive circuit based on converter that impulse level response speed is very fast and the operation is stable possesses: a single chip Microcomputer (MCU) for generating and outputting a pulse level; the controller (U101) is used for receiving the pulse level; the input end of the push-pull circuit (204) is connected with the output end of the pre-drive circuit (201), and the output end of the push-pull circuit (204) is connected with the grid of the IGBT; when the input pulse level is high level, the high level controls the IGBT to be conducted through a push-pull circuit (204); when the input pulse level is low level, the low level controls the IGBT to be cut off through a push-pull circuit (204).

Description

Driving circuit based on frequency converter

Technical Field

The utility model relates to a converter technical field, more specifically say, relate to a drive circuit based on converter.

Background

The frequency converter is a power control device which applies a frequency conversion technology and a microelectronic technology and controls an alternating current motor by changing the frequency of a working power supply. At present, when a frequency converter circuit outputs a pulse signal (PWM) to drive an IGBT (Insulated Gate Bipolar Transistor) to be alternately turned on, a forward voltage and a reverse voltage (pulse level) output by a driving circuit are delayed due to interference of the pulse signal by an external signal, so that the IGBT is not turned on and off in time.

Therefore, how to increase the response speed of the forward and reverse voltages output by the driving circuit becomes a technical problem that needs to be solved urgently by those skilled in the art.

SUMMERY OF THE UTILITY MODEL

The to-be-solved technical problem of the utility model lies in, because pulse signal receives external signal's interference to the aforesaid of prior art, the defect that the delay appears in forward and reverse voltage that leads to the drive circuit output provides the drive circuit based on converter that pulse level response speed is very fast and the operation is stable.

The utility model provides a technical scheme that its technical problem adopted is: a drive circuit based on an inverter is constructed, and the drive circuit is provided with:

the single chip microcomputer is configured in the driving circuit and used for generating and outputting pulse levels;

the input end of the controller is coupled with the signal output end of the singlechip, and the controller is used for receiving the pulse level;

the signal input end of the photoelectric coupler is connected with the signal output end of the controller;

the input end of the front driving circuit is connected with the signal output end of the photoelectric coupler;

the input end of the push-pull circuit is connected with the output end of the pre-drive circuit, and the output end of the push-pull circuit is connected with the grid of the IGBT;

when the input pulse level is high level, the high level controls the IGBT to be conducted through the push-pull circuit;

when the input pulse level is low level, the low level controls the IGBT to be switched off through the push-pull circuit.

In some embodiments, the electronic device further includes a first resistor and a first triode, one end of the first resistor is connected to a signal output end of the single chip, and the other end of the first resistor is coupled to a signal input end of the controller;

the base electrode of the first triode is connected with the other signal output end of the single chip microcomputer, and the collector electrode of the first triode is connected with the other signal input end of the controller;

the pulse level is input to the controller through the first resistor and the first triode.

In some embodiments, the optocoupler includes a first optocoupler and a second optocoupler,

the input end of the first photoelectric coupler is connected with the emitting electrode of the first triode;

the signal input end of the second photoelectric coupler is connected with the signal output end of the controller;

and a signal output end of the second photoelectric coupler is connected with the input end of the pre-drive circuit.

In some embodiments, the pre-driver circuit includes a second transistor and a third transistor,

the base electrodes of the second triode and the third triode are respectively connected with the signal output end of the second photoelectric coupler,

the collector of the second triode is connected with one input end of the push-pull circuit,

the collector of the third triode is connected with the other input end of the push-pull circuit,

and the emitting electrodes of the second triode and the third triode are respectively connected with the other signal output end of the second photoelectric coupler.

In some embodiments, the push-pull circuit includes a fifth transistor and a sixth transistor,

bases of the fifth triode and the sixth triode are respectively connected with a collector of the third triode;

a collector electrode of the fifth triode is respectively connected with a collector electrode of the second triode and a base electrode of the third triode;

and emitting electrodes of the fifth triode and the sixth triode are respectively connected with the grid electrode of the IGBT.

In some embodiments, the controller further comprises a first diode, an anode of the first diode is connected with a collector voltage monitoring terminal of the controller,

the cathode of the first diode is connected with the collector of the IGBT.

The driving circuit based on the frequency converter comprises a single chip microcomputer, a controller, a photoelectric coupler, a front driving circuit and a push-pull circuit, wherein the single chip microcomputer is used for generating and outputting a pulse level; the input end of the push-pull circuit is connected with the output end of the pre-drive circuit, and the output end of the push-pull circuit is connected with the grid of the IGBT; when the input pulse level is high level, the high level controls the IGBT to be conducted through a push-pull circuit; when the input pulse level is low level, the low level controls the IGBT to be cut off through the push-pull circuit. Compared with the prior art, the controller controls the on-off of the push-pull circuit, so that the input PWM pulse level controls the state of the IGBT through the push-pull circuit, the problem that the forward voltage and the reverse voltage (pulse level) output by the driving circuit are delayed due to the fact that the pulse signal is interfered by an external signal can be effectively solved, and the on-off timeliness of the IGBT is further improved.

Drawings

The invention will be further explained with reference to the drawings and examples, wherein:

fig. 1 is a main control circuit diagram of an embodiment of a driving circuit based on a frequency converter;

fig. 2 is a partial control circuit diagram of an embodiment of a driving circuit based on a frequency converter.

Detailed Description

In order to clearly understand the technical features, objects, and effects of the present invention, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Fig. 1 is a main control circuit diagram of an embodiment of a driving circuit based on a frequency converter; fig. 2 is a partial control circuit diagram of an embodiment of a driving circuit based on a frequency converter. As shown in fig. 1 and 2, in the first embodiment of the driving circuit based on the frequency converter of the present invention, the driving circuit based on the frequency converter includes a main control circuit 100 and a control circuit 200.

In order to reduce interference of an external signal with a PWM (pulse width modulation) pulse signal, the drive circuit round-trip wiring of the gate-emitter of the IGBT is connected by a twisted pair.

The main control circuit 100 can provide a transient power or a transient current large enough to enable the IGBT to quickly establish a gate control electric field to be turned on, and has a high input/output electrical isolation performance to insulate the signal circuit from the gate driving circuit.

The control circuit 200 has a very small pulse signal input/output delay time to enable the IGBT to rapidly switch in an on or off state, and has a sensitive overcurrent protection capability.

The control circuit 200 includes a pre-driver circuit 201, an overcurrent protection circuit 202, a voltage clamp circuit 203, and a push-pull circuit 204.

Specifically, the single chip microcomputer MCU is used as a highly integrated processor with a general structure, has strong computing capability, is suitable for processing diagnosis and operation of various data of different information sources, focuses on control, and also has the function of generating PWM pulse signals.

The MCU is disposed in the driving circuit and configured to generate and output a pulse level (i.e., a high level or a low level), and output the generated pulse level to the controller U101.

And the controller U101 is used for amplifying the power of the pulse signal output by the MCU to drive the IGBT.

The signal input end of the controller U101 is connected with the signal output end of the single-chip microcomputer MCU, and the signal input end of the controller U101 is used for receiving the pulse level output by the single-chip microcomputer MCU and outputting the pulse level to the photoelectric coupler (corresponding to U201).

The photocouplers (U102 and U201) transmit electric signals by taking light as a medium, and have good isolation effect on input and output electric signals.

Specifically, a signal input end of the photocoupler (corresponding to U201) is connected with a signal output end (corresponding to pin 14) of the controller U101, and is configured to isolate a pulse level output after amplification by the controller U101 and output the pulse level to the pre-driver circuit 201.

The pre-drive circuit 201 is used for receiving the pulse level output by the photoelectric coupler (corresponding to the U201) and pre-amplifying the pulse level.

Specifically, the input terminal of the pre-driver circuit 201 is connected to the signal output terminal of the photocoupler (corresponding to U201), and is configured to receive the pulse level output by the photocoupler (corresponding to U201) and output the pulse level to the push-pull circuit 204.

The push-pull circuit 204 adopts two power BJT transistors or MOSFET transistors with the same parameters, the two power BJT transistors or MOSFET transistors exist in the circuit in a push-pull mode, each power BJT transistor or MOSFET transistor is responsible for positive and negative half-cycle waveform amplification tasks, and when the circuit works, only one of the two symmetrical power switch transistors is conducted each time, so that the conduction loss is small, and the efficiency is high.

Specifically, an input end of the push-pull circuit 204 is connected to an output end of the pre-driver circuit 201, and an output end of the push-pull circuit 204 is connected to a gate of the IGBT.

When the input pulse level (PWM pulse signal) is high level, a power BJT (corresponding to NPN type) or MOSFET (corresponding to N channel type) in the push-pull circuit 204 is turned on, so that the high level can control the IGBT to be turned on through the push-pull circuit 204.

When the input pulse level is low level, a power BJT (corresponding to PNP type) or MOSFET (corresponding to P-channel type) in the push-pull circuit 204 is turned on, and the low level controls the IGBT to be turned off through the push-pull circuit 204.

The controller U101 controls the on and off of the push-pull circuit 204, so that the input PWM pulse level controls the state of the IGBT through the push-pull circuit 204, the problem that the forward voltage and the reverse voltage (pulse level) output by the driving circuit are delayed due to the interference of the pulse signal by an external signal can be effectively solved, and the on and off timeliness of the IGBT is further improved.

In some embodiments, in order to improve the stability of the input pulse signal, a first resistor R101 and a first transistor VT101 may be disposed in the circuit, wherein the first transistor VT101 is an NPN transistor having switching and amplifying functions.

Specifically, one end of the first resistor R101 is connected to a signal output end of the MCU, and the other end of the first resistor R101 is coupled to a signal input end (corresponding to pin 15) of the controller U101.

The base electrode of the first triode VT101 is connected with the other signal output end of the single chip microcomputer MCU, the collector electrode of the first triode VT101 is connected with the other signal input end (corresponding to 14 pins) of the controller U101, and the pulse level output by the single chip microcomputer MCU is input into the controller U101 through the first resistor R101 and the first triode VT101 to provide a driving signal for the work of the IGBT.

In some embodiments, in order to improve the isolation effect of the pulse signal, photo couplers may be provided as the first photo coupler U102 and the second photo coupler U201.

The input end of the first photoelectric coupler U102 is connected with the emitter of the first triode VT101, and the signal output end of the first photoelectric coupler U102 is used as an overcurrent protection output. That is, when the current signal of the IGBT emitter acquired by the ninth resistor R207 (belonging to the overcurrent protection circuit 202) is greater than the current threshold of the controller U101, the first photocoupler U102 is turned on, outputs the overcurrent protection signal to the single chip MCU, and stops outputting the PWM pulse signal through the single chip MCU, so that the IGBT can stop in time.

The signal input end of the second photoelectric coupler U201 is connected with the signal output end of the controller U101; a signal output end of the second photocoupler U201 is connected to an input end of the pre-driver circuit 201, and the pre-driver circuit 201 is configured to receive the pulse level isolated by the second photocoupler U201.

In some embodiments, the high front-end driver circuit 201 includes a second transistor VT201 and a third transistor VT202, wherein the second transistor VT201 and the third transistor VT202 are NPN transistors having switching and amplifying functions.

Specifically, the bases of the second transistor VT201 and the third transistor VT202 are respectively connected to the signal output terminal of the second photocoupler U201, and are configured to receive the driving level.

The collector of the second transistor VT201 is connected to an input terminal of the push-pull circuit 204 through a fifth resistor R203, and the collector of the third transistor VT202 is connected to another input terminal of the push-pull circuit 204.

The emitting electrodes of the second triode VT201 and the third triode VT202 are respectively connected to the other signal output terminal of the second photocoupler U201.

In some embodiments, the push-pull circuit 204 includes a fifth transistor VT204 and a sixth transistor VT205, wherein the fifth transistor VT204 is an NPN transistor, and the sixth transistor VT205 is a PNP transistor, both of which function as a switch.

Specifically, bases of the fifth transistor VT204 and the sixth transistor VT205 are respectively connected to a collector of the third transistor VT202, and a collector of the fifth transistor VT204 is respectively connected to a collector of the second transistor VT201 and a base of the third transistor VT 202.

The emitters of the fifth transistor VT204 and the sixth transistor VT205 are connected to the gate of the IGBT, respectively.

The working principle is as follows: when the current of 10mA flows through 1us at the 14 pin and the 15 pin of the controller U101, the IGBT is normally turned on, the VCE drops to about 3V, the voltage of the 6 pin is clamped to about 8V, the first voltage regulator diode VS201 has a voltage value of 13V and is not broken down, the fourth transistor VT203 is not turned on, the potential at the point E is about 20V, the second diode D201 (belonging to the voltage clamping circuit 203) is turned off, and the normal operation of the fifth transistor VT204 and the sixth transistor VT205 is not affected.

If no current flows through the 14 pins and the 15 pins of the controller U101, the second triode VT201 and the third triode VT202 are turned on, the third triode VT202 is turned on to turn off the fifth triode VT204 and turn on the sixth triode VT205, the IGBT gate charge is rapidly discharged through the sixth triode VT205, so that the potential of the 3 pin of the controller U101 is reduced to 0V, the IGBT gate-emitter is subjected to a negative bias of about 5V, the IGBT is reliably turned off, meanwhile, the rapid rise of the VCE makes the pin 6 of the controller U101 "float," the discharge of the fourth capacitor C202 makes the potential at the B point 0V, so the first zener diode VS201 is not turned on, the subsequent circuit does not work, and the IGBT is controlled to be normally turned off.

In some embodiments, in order to improve the safety of the operation of the IGBT, a first diode D101 may be provided in the circuit, specifically, an anode of the first diode D101 is connected to a collector voltage monitoring terminal (corresponding to 6 pins) of the controller U101, and a cathode of the first diode D101 is connected to a collector of the IGBT.

If overcurrent occurs, the VCE of the IGBT is too large to turn off the first diode D101, so that the first zener diode VS201 (belonging to the overcurrent protection circuit 202) is broken down, the fourth triode VT203 is turned on, the sixth capacitor C204 discharges through the ninth resistor R207, and the potential of the anode of the second diode D201 decreases, thereby reducing the gate-emitter voltage UGE of the IGBT, completing slow turn-off, and realizing protection of the IGBT.

While the embodiments of the present invention have been described with reference to the accompanying drawings, the present invention is not limited to the above-described embodiments, which are merely illustrative and not restrictive, and many modifications may be made by one skilled in the art without departing from the spirit and scope of the present invention as defined in the appended claims.

Claims

1. A drive circuit based on a frequency converter is characterized by comprising:

2. The frequency converter based drive circuit of claim 1, further comprising

One end of the first resistor is connected with a signal output end of the singlechip, and the other end of the first resistor is coupled to a signal input end of the controller;

3. The frequency converter based drive circuit according to claim 2,

the photoelectric coupler comprises a first photoelectric coupler and a second photoelectric coupler,

4. The frequency converter based drive circuit according to claim 3,

the front driving circuit comprises a second triode and a third triode,

5. The frequency converter based drive circuit according to claim 4,

the push-pull circuit comprises a fifth triode and a sixth triode,

6. The frequency converter based driving circuit according to any one of claims 1 to 5, further comprising a first diode, an anode of the first diode being connected to a collector voltage monitor terminal of the controller,

the cathode of the first diode is connected with the collector of the IGBT.