Inverter short circuit protection circuit

Abstract

The invention belongs to the technical field of circuits, and discloses an inverter short-circuit protection circuit which comprises a port ILOAD, the port ILOAD is connected with one end of a resistor R285, the other end of the resistor R285 is connected with one end of a capacitor C103, a pin 6 of a comparator U1, a pin 3 of the comparator U1 and one end of a resistor R288, and the other end of the capacitor C103 is connected with a port GND; a pin 1 of the comparator U1 is connected with the other end of the resistor R288, one end of the capacitor C113, one end of the resistor R290 and one end of the resistor R293, the other end of the resistor R293 is connected with one end of the resistor R294 and a base electrode of the triode Q49, the other end of the resistor R294 is connected with a port GND and an emitting electrode of the triode Q49, and a collector electrode of the triode Q49 is connected with a port IOVPI. The beneficial effects of the invention are that the driving device controls the switching tube of the inverter according to the sampling result, so that the inverter is protected, the scheme is simple, the cost is low, and the inverter is well protected.

Description

Technical Field

[0001] The present invention relates to the field of circuit technologies, and particularly to an inverter short - circuit protection circuit. Background Art

[0002] An inverter is a device that converts direct current electrical energy (batteries, accumulators) into alternating current (generally 220V, 50Hz sine wave). It consists of an inverter bridge, control logic, and a filtering circuit, and is widely applicable to air conditioners, home theaters, electric grinders, power tools, sewing machines, DVDs, VCDs, computers, TVs, washing machines, range hoods, refrigerators, video recorders, massagers, fans, lighting, etc. It can sample the current and compare the sampled value with the corresponding reference current value. When the sampled value of the inductor current is greater than the reference current value, the semiconductor power switch tubes are turned off according to a certain time sequence, thereby preventing the semiconductor power switch tubes from being burned out due to over - current. In existing devices, a protection circuit is used to protect the inverter, but the circuit structure is relatively complex, the cost is high, and the safety is low.

[0003] Therefore, it is necessary to provide an inverter short - circuit protection circuit to simplify the design, reduce the cost, and improve the product reliability. Summary of the Invention

[0004] The present invention discloses an inverter short - circuit protection circuit, which can effectively solve the technical problems involved in the background art.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] An inverter short - circuit protection circuit includes a port I_LOAD. One end of the port I_LOAD is connected to one end of a resistor R285. The other end of the resistor R285 is connected to one end of a capacitor C103, pin 6 of a comparator U1, pin 3 of the comparator U1, and one end of a resistor R288. The other end of the capacitor C103 is connected to the port GND.

[0007] Pin 1 of the comparator U1 is connected to the other end of the resistor R288, one end of a capacitor C113, one end of a resistor R290, and one end of a resistor R293. The other end of the resistor R293 is connected to one end of a resistor R294 and the base of a triode Q49. The other end of the resistor R294 is connected to the port GND and the emitter of the triode Q49. The collector of the triode Q49 is connected to the port IOVP_I.

[0008] Pin 2 of the comparator U1 is connected to pin 5 of the comparator U1, one end of a resistor R289, one end of a resistor R287, and one end of a capacitor C115. The other end of the resistor R289 and the other end of the capacitor C115 are connected to the port GND.

[0009] Pin 4 of the comparator U1 is connected to one end of the capacitor C104, one end of the capacitor C110, and the port GND;

[0010] Pin 7 of the comparator U1 is connected to one end of the resistor R279. The other end of the resistor R279 is connected to one end of the capacitor C114 and one end of the resistor R286. The other end of the capacitor C114 is connected to the port GND. The other end of the resistor R286 is connected to the other end of the resistor R290, pin 8 of the comparator U1, the other end of the capacitor C104, the other end of the capacitor C110, the other end of the resistor R287, and the port MCU_3.3VA;

[0011] The port I_LOAD is connected to the sampling end of the inverter, and the port IOVP_I is connected to the driving device of the inverter.

[0012] As a preferred improvement of the present invention: The model of the comparator U1 is LM393APWR.

[0013] As a preferred improvement of the present invention: The other end of the resistor R285 is connected to one end of the resistor R292. The other end of the resistor R292 is connected to the port IOVP1, and the port IOVP1 is connected to the single-chip microcomputer.

[0014] As a preferred improvement of the present invention: The single-chip microcomputer is connected to the port MCU_3.3VA to provide a reference voltage.

[0015] As a preferred improvement of the present invention: The driving device is a control chip, and the model 51116 can be adopted.

[0016] As a preferred improvement of the present invention: The inverter includes a port VBUS. The port VBUS is connected to one end of the capacitor C204, pin 1 of the switching tube Q1, and pin 1 of the switching tube Q2. Pin 2 of the switching tube Q1 is connected to pin 1 of the switching tube Q3 and one end of the inductor L6. The other end of the inductor L6 is connected to one end of the capacitor C60. Pin 2 of the switching tube Q2 is connected to pin 1 of the switching tube Q4 and the other end of the capacitor C60. Pin 2 of the switching tube Q3 is connected to pin 2 of the switching tube Q4, the port I_LOAD, one end of the resistor R130, one end of the resistor R28, and one end of the resistor R162. The other end of the capacitor C204 is connected to the other end of the resistor R130, the other end of the resistor R28, and the other end of the resistor R162. Pin 3 of the switching tube Q1, pin 3 of the switching tube Q2, pin 3 of the switching tube Q3, and pin 3 of the switching tube Q4 are connected to the driving device.

[0017] As a preferred improvement of the present invention: The other end of the capacitor C204 is grounded.

[0018] As a preferred improvement of the present invention: the switching transistors Q1, Q2, Q3, and Q4 are IGBTs or MOS transistors.

[0019] The beneficial effects of the present invention are as follows:

[0020] Signal sampling is performed on the inverter. The sampled signal is transmitted to a comparator through a resistor. The comparator outputs a result, which is connected to a driving device through resistors, capacitors, and a triode. The driving device controls the switching transistors of the inverter according to the sampling result, thereby protecting the inverter. The solution is simple, low in cost, and has a good protection effect on the inverter. Description of the Drawings

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings, where:

[0022] Figure 1 is a schematic diagram of a short-circuit protection circuit for an inverter of the present invention;

[0023] Figure 2 is a schematic diagram of the inverter structure;

[0024] Figure 3 is a schematic diagram of the driving part. Detailed Embodiments

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0026] It should be noted that all directional indicators (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relative position relationship and movement conditions between components in a specific posture (as shown in the drawings). If the specific posture changes, the directional indicators will also change accordingly.

[0027] In addition, in the present invention, descriptions such as "first" and "second" are for descriptive purposes only, and should not be construed as indicating or implying their relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0028] In the present invention, unless otherwise clearly defined and limited, terms such as "connection" and "fixation" shall be understood in a broad sense. For example, "fixation" may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and may be the communication inside two components or the interaction relationship between two components, unless otherwise clearly limited. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] In addition, the technical solutions between various embodiments of the present invention can be combined with each other, but it must be based on the ability of those of ordinary skill in the art to implement. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0030] Please refer to Figure 2 As shown, the inverter includes a port VBUS. The port VBUS is connected to one end of a capacitor C204, pin 1 of a switch Q1, and pin 1 of a switch Q2. Pin 2 of the switch Q1 is connected to pin 1 of a switch Q3 and one end of an inductor L6. The other end of the inductor L6 is connected to one end of a capacitor C60. Pin 2 of the switch Q2 is connected to pin 1 of a switch Q4 and the other end of the capacitor C60. Pin 2 of the switch Q3 is connected to pin 2 of the switch Q4, a port I_LOAD, one end of a resistor R130, one end of a resistor R28, and one end of a resistor R162. The other end of the capacitor C204 is connected to the other end of the resistor R130, the other end of the resistor R28, and the other end of the resistor R162. Pin 3 of the switch Q1, pin 3 of the switch Q2, pin 3 of the switch Q3, and pin 3 of the switch Q4 are connected to the driving device. In this embodiment, the other end of the capacitor C204 is grounded, and the switches Q1, Q2, Q3, and Q4 are IGBTs or MOS transistors.

[0031] The above is the full-bridge inverter topology, which consists of switching transistors Q1, Q2, Q3, Q4, and L6, C60. Generally, a CT is used to detect the current of the switching transistors. After experimental tests, without affecting reliability, we removed this device and instead connected current-detecting resistors R130, R28, and R162 in series between GND and I_LOAD to detect the current of the switching transistors. This is beneficial for simplifying the design and reducing costs, and can reduce costs by approximately 50%. The following is the design solution.

[0032] Please refer to Figure 3 As shown, the figure shows the part of the inverter transistor drive device. It receives the microcontroller control signal and converts it into drive voltages A, B, C, D to drive Q1, Q3, Q2, Q4, and IOVP_I is an external control signal of the inverter transistor drive device. It is an external high level of 3.3V. When the external 3.3V is pulled low, the drive voltages A, B, C, D are turned off, and similarly, Q1, Q3, Q2, Q4 are also turned off. In this embodiment, the drive device is a control chip.

[0033] Please refer to Figure 1As shown in the figure, the present invention provides an inverter short-circuit protection circuit, including port I_LOAD. One end of port I_LOAD is connected to one end of resistor R285. The other end of resistor R285 is connected to one end of capacitor C103, pin 6 of comparator U1, pin 3 of comparator U1, and one end of resistor R288. The other end of capacitor C103 is connected to port GND; pin 1 of comparator U1 is connected to the other end of resistor R288, one end of capacitor C113, one end of resistor R290, and one end of resistor R293. The other end of resistor R293 is connected to one end of resistor R294 and the base of triode Q49. The other end of resistor R294 is connected to port GND and the emitter of triode Q49. The collector of triode Q49 is connected to port IOVP_I; pin 2 of comparator U1 is connected to pin 5 of comparator U1, one end of resistor R289, one end of resistor R287, and one end of capacitor C115. The other end of resistor R289 and the other end of capacitor C115 are connected to port GND; pin 4 of comparator U1 is connected to one end of capacitor C104, one end of capacitor C110, and port GND; pin 7 of comparator U1 is connected to one end of resistor R279. The other end of resistor R279 is connected to one end of capacitor C114 and one end of resistor R286. The other end of capacitor C114 is connected to port GND. The other end of resistor R286 is connected to the other end of resistor R290, pin 8 of comparator U1, the other end of capacitor C104, the other end of capacitor C110, the other end of resistor R287, and port MCU_3.3VA; port I_LOAD is connected to the sampling end of the inverter, and port IOVP_I is connected to the driving device of the inverter. In this embodiment, the model of comparator U1 is LM393APWR. The other end of resistor R285 is connected to one end of resistor R292. The other end of resistor R292 is connected to port IOVP1. Port IOVP1 is connected to the single-chip microcomputer, and the single-chip microcomputer is connected to port MCU_3.3VA.

[0034] The above is the short-circuit protection control part, which is composed of comparator U1, resistors, capacitors, triodes, etc. Among them, U1-B is the reverse input terminal 2 connected to R289, R287, and then to the MUC_3.3V reference voltage. After the voltage division of R289 and R287, it is 3.3V*(R289 / (R289+R287)).

[0035] The non-inverting input terminal 3 of U1-B is connected to I_LOAD through R285. As long as the current sampled by R130, R28, and R162 exceeds R289 and the voltage division of R287 occurs, the output terminal 1 of the comparator U1-B is triggered to output a high level, which passes through R293 to Q49 and then the triode pulls down IVOP_I. Since the inverter tube drives the default output of IVOP_I to be 3.3V, after being pulled down by Q49, the driving voltages A, B, C, and D are turned off, and Q1, Q3, Q2, and Q4 are also turned off. At this time, the inverter is in a protection state. If the U1 comparator fails, I_LOAD is connected to R292 through R285 and then to IOVP1, and IOVP1 is connected to the single-chip microcomputer. The single-chip microcomputer can also protect the inverter by turning off the signals of A, B, C, and D through internal calculation, that is, the single-chip microcomputer can output signals to the comparator to drive the switching tubes of the inverter. The above is the short-circuit protection design scheme. This scheme is beneficial to simplify the design, reduce costs, and improve the reliability of the product.

[0036] Although the embodiments of the present invention have been disclosed as above, they are not limited to only the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those familiar with the field, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the illustrated examples shown and described here.

Claims

1. An inverter short-circuit protection circuit, characterized in that: It includes a port I_LOAD, wherein the port I_LOAD is connected to one end of a resistor R285, the other end of the resistor R285 is connected to one end of a capacitor C103, a pin 6 of a comparator U1, a pin 3 of the comparator U1 and one end of a resistor R288, and the other end of the capacitor C103 is connected to a port GND; Pin 1 of the comparator U1 is connected to the other end of the resistor R288, one end of the capacitor C113, one end of the resistor R290 and one end of the resistor R293, the other end of the resistor R293 is connected to one end of the resistor R294 and the base of the transistor Q49, the other end of the resistor R294 is connected to the port GND and the emitter of the transistor Q49, and the collector of the transistor Q49 is connected to the port IOVP_I; Pin 2 of the comparator U1 is connected to pin 5 of the comparator U1, one end of the resistor R289, one end of the resistor R287 and one end of the capacitor C115, and the other end of the resistor R289 and the other end of the capacitor C115 are connected to port GND; Pin 4 of the comparator U1 is connected to one end of the capacitor C104, one end of the capacitor C110 and the port GND; Pin 7 of the comparator U1 is connected to one end of the resistor R279, the other end of the resistor R279 is connected to one end of the capacitor C114 and one end of the resistor R286, the other end of the capacitor C114 is connected to the port GND, the other end of the resistor R286 is connected to the other end of the resistor R290, pin 8 of the comparator U1, the other end of the capacitor C104, the other end of the capacitor C110, the other end of the resistor R287 and the port MCU_3.3VA; The port I_LOAD is connected to a sampling terminal of the inverter, and the port IOVP_I is connected to a driving device of the inverter.

2. The inverter short-circuit protection circuit according to claim 1, characterized in that: The comparator U1 is of model LM393APWR.

3. The inverter short-circuit protection circuit according to claim 1, characterized in that: The other end of the resistor R285 is connected to one end of the resistor R292, the other end of the resistor R292 is connected to the port IOVP1, and the port IOVP1 is connected to the single chip microcomputer.

4. The inverter short-circuit protection circuit according to claim 3, characterized in that: The single chip microcomputer is connected to the port MCU_3.3VA.

5. The inverter short-circuit protection circuit according to claim 1, characterized in that: The driving device is a control chip.

6. The inverter short-circuit protection circuit according to claim 1, characterized in that: The inverter includes a port VBUS, wherein the port VBUS is connected to one end of a capacitor C204, a pin 1 of a switch tube Q1, and a pin 1 of a switch tube Q2, a pin 2 of the switch tube Q1 is connected to a pin 1 of a switch tube Q3 and one end of an inductor L6, the other end of the inductor L6 is connected to one end of a capacitor C60, a pin 2 of the switch tube Q2 is connected to a pin 1 of a switch tube Q4 and the other end of the capacitor C60, a pin 2 of the switch tube Q3 is connected to a pin 2 of the switch tube Q4, a port I_LOAD, one end of a resistor R130, one end of a resistor R28, and one end of a resistor R162, the other end of the capacitor C204 is connected to the other end of the resistor R130, the other end of the resistor R28, and the other end of the resistor R162, and a pin 3 of the switch tube Q1, a pin 3 of the switch tube Q2, a pin 3 of the switch tube Q3, and a pin 3 of the switch tube Q4 are connected to the driving device.

7. The inverter short-circuit protection circuit according to claim 6, characterized in that: The other end of the capacitor C204 is grounded.

8. The inverter short-circuit protection circuit according to claim 6, characterized in that: The switch tube Q1 , the switch tube Q2 , the switch tube Q3 and the switch tube Q4 are IGBTs or MOS tubes.

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