CN212908985U - Protection circuit and inverter - Google Patents
Protection circuit and inverter Download PDFInfo
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- CN212908985U CN212908985U CN202020961423.0U CN202020961423U CN212908985U CN 212908985 U CN212908985 U CN 212908985U CN 202020961423 U CN202020961423 U CN 202020961423U CN 212908985 U CN212908985 U CN 212908985U
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Abstract
The embodiment of the utility model provides a relate to electron electric power technical field, disclose a circuit structure simple, the cost is lower, and protection circuit that the sensitivity is good is applied to the dc-to-ac converter, and it includes: the utility model provides a series connection is at the current sampling circuit on dc-to-ac converter direct current link negative bus, the first amplifier circuit who connects gradually with current sampling circuit, switch circuit, buffer circuit, second amplifier circuit and control circuit, wherein, first amplifier circuit is used for exporting high level signal when detecting the level signal that is higher than first predetermined reference voltage, and second amplifier circuit is used for exporting low level signal when detecting the level signal that is higher than second predetermined reference voltage, and control circuit is arranged in the switching device who cuts off in the dc-to-ac converter when receiving low level signal, the utility model provides a protection circuit can realize the isolation of detected signal and drive signal to and the overcurrent and short-circuit protection of dc-to-ac converter, effectively promotes the interference killing feature of dc-to-ac converter.
Description
Technical Field
The embodiment of the utility model provides a relate to electron electric power technical field, in particular to protection circuit and dc-to-ac converter.
Background
The overcurrent and short-circuit protection circuit is very important in the design and manufacture process of the inverter, and the overcurrent and short-circuit protection circuit greatly determines the safety problem of the inverter in practical use. If the over-current and short-circuit protection circuit fails, the inverter tube is likely to be burnt out when the output of the inverter is short-circuited or over-current, so that the over-current and short-circuit protection circuit has a great effect on the inverter.
In the prior art, overcurrent and short-circuit protection of an IGBT can be divided into a Uge monitoring method or a Uce monitoring method, the two principles are basically similar, and the principle that Uge or Uce is also raised when collector current Ic is raised is utilized, when Uge or Uce exceeds Uge (sat) or Uce (sat), a driving circuit of the IGBT is automatically turned off, because Uge is basically unchanged when a fault occurs, change of Uce is large, and Uge change is small when desaturation occurs, so that the IGBT is difficult to master, and the Uce monitoring technology is generally adopted to protect the IGBT in practice.
In implementing the present invention, the inventors found that there are at least the following problems in the above related art: although the manner of protecting the IGBT by the Uce monitoring technology used in the field of inverters can realize overcurrent and short-circuit protection of the IGBT, a peripheral circuit is complex, the cost is high, isolation of detection signals is difficult to realize, the anti-interference capability is poor, and certain use limitations are realized.
SUMMERY OF THE UTILITY MODEL
To the above-mentioned defect of prior art, the embodiment of the utility model provides an it is better, can realize overflowing and short-circuit protection's protection circuit and dc-to-ac converter to keep apart the effect.
The embodiment of the utility model provides an aim at is realized through following technical scheme:
in order to solve the above technical problem, in a first aspect, the embodiment of the present invention provides a protection circuit for an inverter, including:
the current sampling circuit is connected in series to a negative bus of the inverter direct-current link;
the input end of the first amplifying circuit is connected with the current sampling circuit and is used for outputting a high-level signal when the current sampling circuit is detected to output a level signal higher than a first preset reference voltage;
the control end of the switch circuit is connected with the output end of the first amplifying circuit;
the control end of the isolation circuit is connected with the input end of the switch circuit;
the input end of the second amplifying circuit is connected with the output end of the isolating circuit and used for outputting a low-level signal when the isolating circuit is detected to output a level signal higher than a second preset reference voltage;
and the input end of the control circuit is connected with the output end of the second amplifying circuit and is used for turning off the switching device in the inverter when receiving a low-level signal.
In some embodiments, the current sampling circuit is a current sampling resistor.
In some embodiments, further comprising: a filter circuit connected in parallel with the current sampling circuit.
In some embodiments, the filter circuit comprises:
one end of the first current limiting resistor is connected with the output end of the current sampling circuit;
one end of the first filter capacitor is connected with the other end of the first current-limiting resistor, and the other end of the first filter capacitor is connected with the input end of the current sampling circuit;
and one end of the second current-limiting resistor is connected with the other end of the first current-limiting resistor, and the other end of the second current-limiting resistor is connected with the input end of the first amplifying circuit.
In some embodiments, the first amplification circuit comprises:
one end of the third current limiting resistor is used for inputting the first preset reference voltage;
and the reverse phase input end of the first comparator is connected with the other end of the third current-limiting resistor, the positive phase input end of the first comparator is connected with the current sampling circuit, the output end of the first comparator is connected with the control end of the switch circuit, and the power supply input end of the first comparator is connected with a direct current power supply.
In some embodiments, the switching circuit comprises:
one end of the first voltage dividing resistor is used for inputting a direct current power supply;
one end of the second voltage-dividing resistor is connected with the other end of the first voltage-dividing resistor, and the other end of the second voltage-dividing resistor is grounded;
and the base electrode of the triode is connected with the other end of the first divider resistor, the collector electrode of the triode is connected with the input end of the isolation circuit, and the emitter electrode of the triode is grounded.
In some embodiments, the isolation circuit comprises:
one end of the third voltage dividing resistor is used for inputting a direct current power supply;
a fourth voltage dividing resistor, one end of which is connected with the other end of the third voltage dividing resistor, and the other end of which is connected with the input end of the switch circuit;
the optocoupler comprises a light emitting diode and a phototriode, wherein the anode of the light emitting diode is connected with one end of the fourth voltage-dividing resistor, and the cathode of the light emitting diode is connected with the other end of the fourth voltage-dividing resistor;
one end of the second filter capacitor is respectively connected with the collector of the phototriode and the other direct current power supply, and the other end of the second filter capacitor is grounded;
and one end of the fifth voltage-dividing resistor is respectively connected with the emitter of the phototriode and the input end of the second amplifying circuit, and the other end of the fifth voltage-dividing resistor is grounded.
In some embodiments, the second amplification circuit comprises:
one end of the fourth current limiting resistor is connected with the output end of the isolation circuit;
the inverting input end of the second comparator is connected with the other end of the fourth current-limiting resistor, and the power supply input end of the second comparator is connected with a direct-current power supply;
one end of the fifth current-limiting resistor is connected with the direct-current power supply, and the other end of the fifth current-limiting resistor is connected with the positive phase input end of the second comparator;
one end of the sixth divider resistor is connected with the positive phase input end of the second comparator, and the other end of the sixth divider resistor is grounded;
one end of the third filter capacitor is connected with the positive phase input end of the second comparator, and the other end of the third filter capacitor is grounded;
one end of the fourth filter capacitor is connected with the power supply input end of the second comparator, and the other end of the fourth filter capacitor is grounded;
and the cathode of the quick recovery diode is connected with the output end of the second comparator, and the anode of the quick recovery diode is connected with the control circuit.
In some embodiments, the control circuit comprises:
the input end of the DSP control circuit module is connected with the output end of the second amplifying circuit, and the output end of the DSP control circuit module is used for outputting a PWM (pulse width modulation) driving signal;
one end of the seventh divider resistor is connected with a direct current power supply;
the four input ends of the and gate chip are respectively connected with the output end of the second amplifying circuit, the other end of the seventh divider resistor and the input end of the DSP control circuit module, and the four control ends of the and gate chip are connected with the output end of the DSP control circuit module;
and the input end of the IGBT driving circuit module is connected with the four output ends of the AND gate chip, and the output end of the IGBT driving circuit module is used for outputting a control signal for turning off a switching device in the inverter.
In order to solve the above technical problem, in a second aspect, the embodiment of the present invention provides an inverter, including:
a direct current link;
the input end of the inverter bridge is connected with the output end of the direct current link;
the input end of the voltage transformation link is connected with the output end of the inverter bridge;
and the protection circuit according to the first aspect, wherein the protection circuit is disposed on a negative bus between the dc link and the inverter bridge.
Compared with the prior art, the beneficial effects of the utility model are that: be different from prior art's condition, the embodiment of the utility model provides a protection circuit is provided in, is applied to the dc-to-ac converter, and it includes: the protection circuit provided by the embodiment of the invention can realize the isolation of detection signals and driving signals, and ensure the over-current and short-circuit protection of the inverter and the IGBT while ensuring the over-current and short-circuit protection of the inverter and the IGBT, the anti-interference capability of the inverter is improved, and the circuit is simple in structure, low in cost and good in sensitivity.
Drawings
One or more embodiments are illustrated by the accompanying figures in the drawings that correspond thereto and are not to be construed as limiting the embodiments, wherein elements/modules and steps having the same reference numerals are represented by like elements/modules and steps, unless otherwise specified, and the drawings are not to scale.
Fig. 1 is a schematic block diagram of a protection circuit provided in a first embodiment of the present invention;
fig. 2 is a schematic structural diagram of a protection circuit provided in a first embodiment of the present invention;
fig. 3 is a schematic block diagram of an inverter provided in an embodiment of the present invention;
fig. 4 is a schematic structural diagram of an inverter provided in the second embodiment of the present invention.
Detailed Description
The present invention will be described in detail with reference to the following embodiments. The following examples will assist those skilled in the art in further understanding the present invention, but are not intended to limit the invention in any way. It should be noted that various changes and modifications can be made by one skilled in the art without departing from the spirit of the invention. These all belong to the protection scope of the present invention.
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
It should be noted that, if not conflicted, the various features of the embodiments of the invention can be combined with each other and are within the scope of protection of the present application. In addition, although the functional blocks are divided in the device diagram, in some cases, the blocks may be divided differently from those in the device. Further, the terms "first," "second," and the like, as used herein, do not limit the data and the execution order, but merely distinguish the same items or similar items having substantially the same functions and actions.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
Specifically, the embodiments of the present invention will be further explained with reference to the drawings.
Example one
An embodiment of the present invention provides a protection circuit, please refer to fig. 1, which shows a schematic block diagram of a protection circuit provided by an embodiment of the present invention, the protection circuit 100 includes: a current sampling circuit 110, a first amplifying circuit 120, a switching circuit 130, an isolating circuit 140, a second amplifying circuit 150, and a control circuit 160.
The current sampling circuit 110 is configured to be connected in series to the negative bus of the inverter dc link.
The input end of the first amplifying circuit 120 is connected to the current sampling circuit 110, and the first amplifying circuit 120 is configured to output a high level signal when detecting that the current sampling circuit 110 outputs a level signal higher than a first preset reference voltage. Specifically, the first preset reference voltage may be set according to actual needs.
The control terminal of the switching circuit 130 is connected to the output terminal of the first amplifying circuit 120.
The control terminal of the isolation circuit 140 is connected to the input terminal of the switching circuit 130.
The input end of the second amplifying circuit 150 is connected to the output end of the isolating circuit 140, and the second amplifying circuit 150 is configured to output a low level signal when detecting that the isolating circuit 140 outputs a level signal higher than a second preset reference voltage. Specifically, the second preset reference voltage may be set according to actual needs.
An input terminal of the control circuit 160 is connected to an output terminal of the second amplifying circuit 150, and is configured to turn off the switching device in the inverter when receiving a low level signal.
When the protection circuit 100 of the embodiment of the present invention is in operation, the current sampling circuit 110 collects level signals on the inverter in real time, when the inverter is short-circuited, the current on the negative bus suddenly rises to generate a peak current, and at this time, the current sampling circuit 110 detects that the level signals are higher than a safety voltage set by the system, that is, the first preset reference voltage, or when the current on the inverter is suddenly too large, the level signals detected on the bus are also higher than the first preset reference voltage; when the first amplifying circuit 120 detects that the current sampling circuit 110 outputs a level signal higher than a first preset reference voltage, the first amplifying circuit 120 outputs a high level signal, so as to control the switching circuit 130 to be turned on, the level of the input end of the switching circuit 130 is raised, so as to control the isolation circuit 140 to be turned on, and the isolation circuit 140 outputs a high level signal; at this time, the second amplifying circuit 150 detects a level signal higher than a second preset reference voltage, and the second amplifying circuit 150 outputs a low level signal, so that the control circuit 160 turns off the switching device in the inverter, thereby implementing overcurrent and short-circuit protection of the inverter.
In some embodiments, please refer to fig. 2, which illustrates a circuit structure of a protection circuit according to an embodiment of the present invention, wherein,
optionally, the current sampling circuit is a current sampling resistor R19.
Optionally, the protection circuit 100 further includes: a filter circuit 170, wherein the filter circuit 170 is connected in parallel with the current sampling circuit 110.
Optionally, the filter circuit 170 includes: the circuit comprises a first current limiting resistor R46, a first filter capacitor C12 and a second current limiting resistor R32. One end (1) of the first current limiting resistor R46 is an input end of the filter circuit 170, and the other end (2) of the second current limiting resistor R32 is an output end of the filter circuit 170.
One end of the first current limiting resistor R46 is connected to the output end of the current sampling circuit 110; one end of the first filter capacitor C12 is connected to the other end of the first current limiting resistor R46, and the other end of the first filter capacitor C12 is connected to the input end of the current sampling circuit 110; one end of the second current limiting resistor R32 is connected to the other end of the first current limiting resistor R46, and the other end of the second current limiting resistor R32 is connected to the input terminal of the first amplifying circuit 120.
Optionally, the first amplifying circuit 120 includes: a third current limiting resistor R26 and a first comparator U4. The non-inverting input terminal of the first comparator U4 is the input terminal of the first amplifying circuit 120, and the output terminal of the first comparator U4 is the output terminal of the first amplifying circuit 120.
One end of the third current limiting resistor R26 is used for inputting the first preset reference voltage V _ Ref; an inverting input terminal of the first comparator U4 is connected to the other terminal of the third current limiting resistor R26, a non-inverting input terminal of the first comparator U4 is connected to the current sampling circuit 110, an output terminal of the first comparator U4 is connected to a control terminal of the switching circuit 130, and a power input terminal of the first comparator U4 is connected to a +18V dc power supply.
Optionally, the switching circuit 130 includes: the voltage regulator comprises a first voltage-dividing resistor R27, a second voltage-dividing resistor R35 and a transistor Q7. The base of the transistor Q7 is the control terminal of the switch circuit 130, the collector of the transistor Q7 is the input terminal of the switch circuit 130, and the emitter of the transistor Q7 is the output terminal of the switch circuit 130.
One end of the first voltage dividing resistor R27 is used for inputting a +18V direct current power supply; one end of the second voltage-dividing resistor R35 is connected with the other end of the first voltage-dividing resistor R27, and the other end of the second voltage-dividing resistor R35 is grounded; the base of the transistor Q7 is connected to the other end of the first voltage-dividing resistor R27, the collector of the transistor Q7 is connected to the input of the isolation circuit 140, and the emitter of the transistor Q7 is grounded.
Optionally, the isolation circuit 140 includes: the voltage divider comprises a third voltage dividing resistor R22, a fourth voltage dividing resistor R24, an optical coupler U2, a second filter capacitor C10 and a fifth voltage dividing resistor R23. The cathode (2) of a light emitting diode in the optocoupler U2 is a control end of the isolation circuit 140, one end (1) of the third voltage division resistor R22 is an input end of the isolation circuit 140, and an emitter (3) of a phototriode in the optocoupler U2 is an output end of the isolation circuit 140.
One end of the third voltage dividing resistor R22 is used for inputting a +18V direct current power supply; one end of the fourth voltage dividing resistor R24 is connected to the other end of the third voltage dividing resistor R22, and the other end of the fourth voltage dividing resistor R24 is connected to the input terminal of the switch circuit 130; the optocoupler U2 comprises a light emitting diode and a phototriode, wherein an anode (1) of the light emitting diode is connected with one end of the fourth voltage-dividing resistor R24, and a cathode (2) of the light emitting diode is connected with the other end of the fourth voltage-dividing resistor R24; one end of the second filter capacitor C10 is respectively connected with the collector (4) of the phototriode and another +5V direct current power supply, and the other end of the second filter capacitor C10 is grounded; one end of the fifth voltage-dividing resistor R23 is respectively connected with the emitter (3) of the phototriode and the input end of the second amplifying circuit 150, and the other end of the fifth voltage-dividing resistor R23 is grounded.
Optionally, the second amplifying circuit 150 includes: the circuit comprises a fourth current limiting resistor R28, a second comparator U5, a fifth current limiting resistor R31, a sixth voltage dividing resistor R36, a third filter capacitor C13, a fourth filter capacitor C11 and a fast recovery diode D6. One end (1) of the fourth current limiting resistor R28 is the input end of the second amplifying circuit 150, and the anode of the fast recovery diode D6 is the output end of the second amplifying circuit 150.
One end of the fourth current limiting resistor R28 is connected to the output end of the isolation circuit 140; the inverting input end of the second comparator U5 is connected with the other end of the fourth current limiting resistor R28, and the power supply input end of the second comparator U5 is connected with a +5V direct-current power supply; one end of the fifth current limiting resistor R31 is connected to the +5V dc power supply, and the other end of the fifth current limiting resistor R31 is connected to the non-inverting input terminal of the second comparator U5; one end of the sixth voltage-dividing resistor R36 is connected to the non-inverting input terminal of the second comparator U5, and the other end of the sixth voltage-dividing resistor R36 is grounded; one end of the third filter capacitor C13 is connected to the non-inverting input terminal of the second comparator U5, and the other end of the third filter capacitor C13 is grounded; one end of the fourth filter capacitor C11 is connected to the power input end of the second comparator U5, and the other end of the fourth filter capacitor C11 is grounded; the cathode of the fast recovery diode D6 is connected to the output of the second comparator U5, and the anode of the fast recovery diode D6 is connected to the control circuit 160.
Optionally, the control circuit 160 includes: the circuit comprises a DSP control circuit module, a seventh divider resistor R25, an AND gate chip U1 and an IGBT drive circuit module. The four input ends (2, 4, 10, 12) of the and gate chip U1 and the input end INVOCP of the DSP control circuit module are input ends of the control circuit 160, and the four output ends (SPWM1ML, SPWM1MH, SPWM2ML, SPWM2MH) of the IGBT driving circuit module are output ends of the control circuit 160.
The input end INVOCP of the DSP control circuit module is connected with multiple output ends of the second amplifying circuit 150, and the output end (SPWM _1L, SPWM _1H, SPWM _2L, SPWM _2H) of the DSP control circuit module is used for outputting a PWM driving signal; one end of the seventh voltage-dividing resistor R25 is connected with a +3.3V direct-current power supply; four input ends (2, 4, 10, 12) of the and-gate chip U1 are respectively connected to the output end of the second amplifying circuit 150, the other end (2) of the seventh voltage-dividing resistor R25 and the input end INVOCP of the DSP control circuit module, and four control ends (SPWM _1L, SPWM _1H, SPWM _2L, SPWM _2H) of the and-gate chip U1 are connected to the output end (SPWM _1L, SPWM _1H, SPWM _2L, SPWM _2H) of the DSP control circuit module; the input end (SPWM _1DL, SPWM _1DH, SPWM _2DL, SPWM _2DH) of the IGBT drive circuit module is connected with four output ends (SPWM _1DL, SPWM _1DH, SPWM _2DL, SPWM _2DH) of the AND gate chip U1, and the output end (SPWM1ML, SPWM1MH, SPWM2ML, SPWM2MH) of the IGBT drive circuit module is used for outputting a drive signal for turning off a switching device in the inverter.
When the bus current is too large, the current flowing through the current sampling resistor R19 is large, the voltage drop across the current sampling resistor R19 rises, the non-inverting input end of the first comparator U4 receives the voltage drop, when the voltage drop is higher than the first predetermined reference voltage received at the inverting input of the first comparator U4, the first comparator U4 outputs a high level signal, the base of the transistor Q7 is turned on after receiving the high level signal, the level of the collector of the transistor Q7 is raised, therefore, the optocoupler U2 is turned on, the inverting input end of the second comparator U5 outputs a low level signal after receiving a level signal higher than a second preset reference voltage, the AND gate chip U1 switches off a control signal through hardware, and simultaneously, after the DSP control circuit module receives the level signal, starting software protection and shutting down the output of the inverter.
Example two
The embodiment of the present invention provides an inverter, please refer to fig. 3, which shows a schematic block diagram of an inverter provided by the embodiment of the present invention, the inverter 200 includes: a direct current link 210, an inverter bridge 220, a transformation link 230 and a protection circuit 100. The input end of the inverter bridge 220 is connected to the output end of the dc link 210, the input end of the transformer link 230 is connected to the output end of the inverter bridge 220, and the protection circuit 100 is disposed on the negative bus between the dc link 210 and the inverter bridge 220.
Specifically, reference may be made to fig. 4, which illustrates a structure of an inverter, wherein the inverter 220 is formed by a switch Q1, a switch Q2, a switch Q5, a switch Q6, and related devices and connections thereof, bases of the four switches are respectively connected to four output terminals (SPWM1ML, SPWM1MH, SPWM2ML, SPWM2MH) of an IGBT driving circuit module in the protection circuit 100 as shown in fig. 2, and the switches are turned on or off according to a received control signal, so as to turn off the inverter when the protection circuit 100 detects a short circuit or an overcurrent, thereby protecting electronic components in the inverter.
It should be noted that the protection circuit 100 according to the embodiment of the present invention is the protection circuit 100 according to the first embodiment, and the specific circuit structure and connection mode of the protection circuit 100 refer to the first embodiment and fig. 1 and/or fig. 2, which are not described in detail herein.
The embodiment of the utility model provides an in provide a protection circuit is applied to the dc-to-ac converter, and it includes: the protection circuit provided by the embodiment of the invention can realize the isolation of detection signals and driving signals, and ensure the over-current and short-circuit protection of the inverter and the IGBT while ensuring the over-current and short-circuit protection of the inverter and the IGBT, the anti-interference capability of the inverter is improved, and the circuit is simple in structure, low in cost and good in sensitivity.
It should be noted that the above-described device embodiments are merely illustrative, where the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit it; within the idea of the invention, also technical features in the above embodiments or in different embodiments can be combined, steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not depart from the spirit and scope of the present invention.
Claims (10)
1. A protection circuit, applied to an inverter, comprising:
the current sampling circuit is connected in series to a negative bus of the inverter direct-current link;
the input end of the first amplifying circuit is connected with the current sampling circuit and is used for outputting a high-level signal when the current sampling circuit is detected to output a level signal higher than a first preset reference voltage;
the control end of the switch circuit is connected with the output end of the first amplifying circuit;
the control end of the isolation circuit is connected with the input end of the switch circuit;
the input end of the second amplifying circuit is connected with the output end of the isolating circuit and used for outputting a low-level signal when the isolating circuit is detected to output a level signal higher than a second preset reference voltage;
and the input end of the control circuit is connected with the output end of the second amplifying circuit and is used for turning off the switching device in the inverter when receiving a low-level signal.
2. The protection circuit of claim 1,
the current sampling circuit is a current sampling resistor.
3. The protection circuit of claim 2, further comprising:
a filter circuit connected in parallel with the current sampling circuit.
4. The protection circuit of claim 3, wherein the filter circuit comprises:
one end of the first current limiting resistor is connected with the output end of the current sampling circuit;
one end of the first filter capacitor is connected with the other end of the first current-limiting resistor, and the other end of the first filter capacitor is connected with the input end of the current sampling circuit;
and one end of the second current-limiting resistor is connected with the other end of the first current-limiting resistor, and the other end of the second current-limiting resistor is connected with the input end of the first amplifying circuit.
5. The protection circuit according to any one of claims 1 to 4, wherein the first amplification circuit includes:
one end of the third current limiting resistor is used for inputting the first preset reference voltage;
and the reverse phase input end of the first comparator is connected with the other end of the third current-limiting resistor, the positive phase input end of the first comparator is connected with the current sampling circuit, the output end of the first comparator is connected with the control end of the switch circuit, and the power supply input end of the first comparator is connected with a direct current power supply.
6. The protection circuit according to any one of claims 1 to 4, wherein the switching circuit includes:
one end of the first voltage dividing resistor is used for inputting a direct current power supply;
one end of the second voltage-dividing resistor is connected with the other end of the first voltage-dividing resistor, and the other end of the second voltage-dividing resistor is grounded;
and the base electrode of the triode is connected with the other end of the first divider resistor, the collector electrode of the triode is connected with the input end of the isolation circuit, and the emitter electrode of the triode is grounded.
7. The protection circuit according to any one of claims 1 to 4, wherein the isolation circuit comprises:
one end of the third voltage dividing resistor is used for inputting a direct current power supply;
a fourth voltage dividing resistor, one end of which is connected with the other end of the third voltage dividing resistor, and the other end of which is connected with the input end of the switch circuit;
the optocoupler comprises a light emitting diode and a phototriode, wherein the anode of the light emitting diode is connected with one end of the fourth voltage-dividing resistor, and the cathode of the light emitting diode is connected with the other end of the fourth voltage-dividing resistor;
one end of the second filter capacitor is respectively connected with the collector of the phototriode and the other direct current power supply, and the other end of the second filter capacitor is grounded;
and one end of the fifth voltage-dividing resistor is respectively connected with the emitter of the phototriode and the input end of the second amplifying circuit, and the other end of the fifth voltage-dividing resistor is grounded.
8. The protection circuit according to any one of claims 1 to 4, wherein the second amplification circuit includes:
one end of the fourth current limiting resistor is connected with the output end of the isolation circuit;
the inverting input end of the second comparator is connected with the other end of the fourth current-limiting resistor, and the power supply input end of the second comparator is connected with a direct-current power supply;
one end of the fifth current-limiting resistor is connected with the direct-current power supply, and the other end of the fifth current-limiting resistor is connected with the positive phase input end of the second comparator;
one end of the sixth divider resistor is connected with the positive phase input end of the second comparator, and the other end of the sixth divider resistor is grounded;
one end of the third filter capacitor is connected with the positive phase input end of the second comparator, and the other end of the third filter capacitor is grounded;
one end of the fourth filter capacitor is connected with the power supply input end of the second comparator, and the other end of the fourth filter capacitor is grounded;
and the cathode of the quick recovery diode is connected with the output end of the second comparator, and the anode of the quick recovery diode is connected with the control circuit.
9. The protection circuit according to any one of claims 1 to 4, wherein the control circuit includes:
the input end of the DSP control circuit module is connected with the output end of the second amplifying circuit, and the output end of the DSP control circuit module is used for outputting a PWM (pulse width modulation) driving signal;
one end of the seventh divider resistor is connected with a direct current power supply;
the four input ends of the and gate chip are respectively connected with the output end of the second amplifying circuit, the other end of the seventh divider resistor and the input end of the DSP control circuit module, and the four control ends of the and gate chip are connected with the output end of the DSP control circuit module;
and the input end of the IGBT driving circuit module is connected with the four output ends of the AND gate chip, and the output end of the IGBT driving circuit module is used for outputting a control signal for turning off a switching device in the inverter.
10. An inverter, comprising:
a direct current link;
the input end of the inverter bridge is connected with the output end of the direct current link;
the input end of the voltage transformation link is connected with the output end of the inverter bridge;
and a protection circuit as claimed in any one of claims 1 to 9, said protection circuit being arranged on a negative bus between said dc link and said inverter bridge.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020961423.0U CN212908985U (en) | 2020-05-29 | 2020-05-29 | Protection circuit and inverter |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202020961423.0U CN212908985U (en) | 2020-05-29 | 2020-05-29 | Protection circuit and inverter |
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| CN212908985U true CN212908985U (en) | 2021-04-06 |
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