CN217956688U

CN217956688U - Bus voltage protection circuit

Info

Publication number: CN217956688U
Application number: CN202221810139.9U
Authority: CN
Inventors: 付琪琪; 杨帆; 徐毛毛
Original assignee: Gree Electric Appliances Inc of Zhuhai
Current assignee: Gree Electric Appliances Inc of Zhuhai
Priority date: 2022-07-14
Filing date: 2022-07-14
Publication date: 2022-12-02
Anticipated expiration: 2032-07-14

Abstract

The utility model discloses a bus voltage protection circuit, this circuit includes: the sampling circuit is used for sampling bus voltage; the comparison circuit is connected with the sampling circuit and used for comparing the bus voltage obtained by sampling with the reference voltage and outputting a comparison result signal; and the relay is connected with the output end of the comparison circuit, and is switched off under the condition that the bus voltage obtained by sampling is greater than the reference voltage according to the comparison result. Through the utility model discloses, can solve the photovoltaic air conditioner because of the photovoltaic response speed that is incorporated into the power networks is slow, bus voltage rises rapidly, leads to the problem of MOS pipe excessive pressure damage, has reached the technological effect who improves the reliability of compressor drive plate.

Description

Bus voltage protection circuit

Technical Field

The utility model relates to the technical field of circuits, particularly, relate to a bus voltage protection circuit.

Background

When the commercial power and the photovoltaic are connected to the grid, the photovoltaic air conditioner can generate the condition of instantaneous lifting of instantaneous open-circuit voltage, if the response speed is slow, the unstable control condition of the compressor can be generated, and the overcurrent protection of the compressor can be caused, so that the bus voltage lifting of a compressor driving plate is caused, and finally, the overvoltage damage of a switching power supply MOS (MOSFET, field effect transistor) on the compressor driving plate is caused, and the normal operation of a unit is influenced.

Aiming at the problem that a switching power supply on a driving board is easy to damage in the photovoltaic grid connection process in the prior art, an effective solution is not provided at present.

SUMMERY OF THE UTILITY MODEL

The embodiment of the utility model provides an in provide a bus voltage protection circuit to lead to the problem that switching power supply damaged on the drive plate easily when the photovoltaic is incorporated into the power networks among the solution prior art.

In order to solve the technical problem, the utility model provides a bus voltage protection circuit, include: the sampling circuit is used for sampling bus voltage; the comparison circuit is connected with the sampling circuit and used for comparing the bus voltage obtained by sampling with the reference voltage and outputting a comparison result signal; and the relay is connected with the output end of the comparison circuit, and is switched off under the condition that the bus voltage obtained by sampling is greater than the reference voltage according to the comparison result.

Further, the sampling circuit includes: the circuit comprises a first resistor, a second resistor and a third resistor, wherein a first end of the second resistor is connected with the first resistor, and a second end of the second resistor is connected with the third resistor and a first input end of a comparison circuit.

Furthermore, a first input end of the comparison circuit is connected with the sampling circuit, and a second input end of the comparison circuit is connected with the reference voltage circuit.

Further, the reference voltage circuit includes: the first end of the fourth resistor is connected with a power supply voltage, the second end of the fourth resistor is connected with the second input end of the comparison circuit, the first end of the fifth resistor is grounded, and the second end of the fifth resistor is connected with the second input end of the comparison circuit and the second end of the fourth resistor.

Further, the comparison circuit is a comparator, a first input end of the comparator is an anode of the comparator, and a second input end of the comparator is a cathode of the comparator.

Further, the output end of the comparator is connected with the relay through a gate circuit.

Furthermore, a first input end of the gate circuit is connected with an output end of the comparison circuit, a second input end of the gate circuit is connected with an output signal of the DSP control unit, and an output end of the gate circuit is connected with a first end of the relay coil.

Further, a second end of the relay coil is connected to a fixed voltage.

Further, the gate circuit includes: or, and gate.

Use the technical scheme of the utility model, come sampling bus voltage through setting up sampling circuit, then carry out the comparison with reference voltage through comparison circuit with the bus voltage that the sampling obtained, output comparison result signal, and under the bus voltage that obtains at the sampling was greater than reference voltage's the condition, the control relay is turn-offed, thereby can solve the photovoltaic air conditioner because of the photovoltaic response speed that is incorporated into the power networks is slow, bus voltage rises rapidly, lead to the problem of MOS pipe overvoltage damage, the technological effect of the reliability of improvement compressor drive plate has been reached.

Drawings

Fig. 1 is a circuit schematic diagram of a bus voltage protection circuit according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a conventional charging circuit;

fig. 3 is a bus over-voltage fast protection circuit according to an embodiment of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention will be described in further detail with reference to the accompanying drawings, 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 skilled in the art without creative efforts belong to the protection scope of the present invention.

The terminology used in the embodiments of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used in the embodiments of the present invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise, and "a plurality" typically includes at least two.

It should be understood that the term "and/or" as used herein is merely one type of association that describes an associated object, meaning that three relationships may exist, e.g., a and/or B may mean: a exists alone, A and B exist simultaneously, and B exists alone. In addition, the character "/" herein generally indicates that the former and latter related objects are in an "or" relationship.

It should be understood that although the terms first, second, third, etc. may be used to describe the resistors, inputs, etc. in embodiments of the present invention, these resistors, inputs, etc. should not be limited to these terms. These terms are only used to distinguish between resistors, inputs, etc. For example, a first resistance may also be referred to as a second resistance, and similarly, a second resistance may also be referred to as a first resistance, without departing from the scope of embodiments of the present invention.

The words "if", as used herein may be interpreted as "at \8230; \8230whenor" when 8230; \8230when or "in response to a determination" or "in response to a detection", depending on the context. Similarly, the phrase "if determined" or "if detected (a stated condition or event)" may be interpreted as "upon determining" or "in response to determining" or "upon detecting (a stated condition or event)" or "in response to detecting (a stated condition or event)", depending on the context.

It is also noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that an article or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such article or apparatus. Without further limitation, an element defined by the phrase "comprising one of 8230, and" comprising 8230does not exclude the presence of additional like elements in articles or devices comprising the element.

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

Example 1

Fig. 1 is a schematic circuit diagram of a bus voltage protection circuit provided in the present application, which may include: a sampling circuit 101 for sampling a bus voltage; the comparison circuit 102 is connected with the sampling circuit and used for comparing the bus voltage obtained by sampling with the reference voltage and outputting a comparison result signal; and the relay 103 is connected with the output end of the comparator, and is switched off under the condition that the bus voltage obtained by sampling is greater than the reference voltage according to the comparison result.

The sampling circuit 101 may include: the comparator comprises a first resistor, a second resistor and a third resistor, wherein a first end of the second resistor is connected with the first resistor, and a second end of the second resistor is connected with the third resistor and a first input end of the comparator.

The first input of the comparator circuit 102 may be coupled to the sampling circuit and the second input of the comparator circuit may be coupled to the reference voltage circuit 104.

The reference voltage circuit may include: the first end of the fourth resistor is connected with a power supply voltage, the second end of the fourth resistor is connected with the second input end of the comparison circuit, the first end of the fifth resistor is grounded, and the second end of the fifth resistor is connected with the second input end of the comparison circuit and the second end of the fourth resistor.

In a specific implementation, the comparison circuit may be a comparator, the first input terminal of the comparator may be a positive electrode of the comparator, the second input terminal of the comparator may be a negative electrode of the comparator, of course, the first input terminal of the comparator may be a negative electrode of the comparator, and the second input terminal of the comparator may be a positive electrode of the comparator, which may be specifically set according to an actual scene and a setting requirement, which is not limited in this application. Further, the comparison circuit may be implemented by a comparator, or may be implemented by other components, and only needs to implement a function of comparing with the reference voltage.

The output end of the comparison circuit may be connected to the relay through a gate circuit, specifically, a first input end of the gate circuit is connected to the output end of the comparison circuit, a second input end of the gate circuit is connected to an output Signal of a DSP (Digital Signal Processing) control unit, and an output end of the gate circuit is connected to a first end of the relay coil. For a relay, the second end of the relay coil may be connected to a fixed voltage.

The gate circuit may be: or, and gate. Specifically, for the gate circuit, only the on and off of the relay need to be controlled by the bus voltage sampling signal and the DSP control signal, and what type of gate circuit is specifically selected may be selected according to actual conditions and needs, which is not limited in the present application.

The bus voltage protection circuit can be applied to the photovoltaic air conditioner to solve the problem that the photovoltaic air conditioner is damaged by overvoltage of the MOS tube due to the fact that the photovoltaic grid-connected response speed is low and the bus voltage rises rapidly, and the technical effect of improving the reliability of the compressor driving plate is achieved

Example 2

The above method is described below with reference to a specific example, however, it should be noted that the specific example is only for better describing the present application and is not to be construed as limiting the present application.

In order to solve the problem that the overvoltage damage of an MOS (metal oxide semiconductor) tube is caused by the fact that the response speed of a photovoltaic grid-connected air conditioner is low and the bus voltage rises rapidly, and improve the reliability of a compressor driving plate, the over-high bus voltage rapid protection circuit is provided in the embodiment.

As shown in fig. 2, a schematic diagram of a conventional charging circuit may include: the power supply comprises a relay TR1, a diode D1, resistors R1-R5, capacitors C1 and C2, a primary winding L of a switching power supply, an MOS (metal oxide semiconductor) tube Q and a control unit; the rectified bus voltage charges a bus capacitor after passing through a relay TR1 and supplies power to a primary side of a switching power supply, and when photovoltaic grid connection is carried out, if the bus voltage rapidly rises and exceeds the voltage bearable by a drain-source electrode of an MOS (metal oxide semiconductor) of a switching power supply circuit, an MOS is easy to be damaged by overvoltage;

as shown in fig. 2, the resistors R1, R2 and R3 form a bus voltage sampling circuit, but the sampled bus voltage signal is used for controlling the frequency of the compressor by the DSP, and does not participate in the relay control, when the photovoltaic grid connection is instantaneous, the bus voltage rapidly rises and exceeds the voltage that can be borne by the Q drain-source electrode of the MOS transistor, the drain-source electrode of the MOS transistor is broken down, and the overvoltage is damaged;

as shown in fig. 3, the present embodiment provides a fast protection circuit for bus overvoltage, which may include: the circuit comprises a relay TR1, a diode D1, an OR gate U1, a comparator U2, resistors R1, R2, R3, R4, R5, R6, R7 and R8, capacitors C1, C2 and C3, a primary winding L of a switching power supply, an MOS (metal oxide semiconductor) tube Q and a control unit.

As shown in fig. 3, the resistors R4, R5, and R6 constitute a bus voltage sampling circuit, one end of the resistor R1 is connected to the VCC power supply, the other end is connected to the negative electrode of the comparator, one end of the resistor R2 is connected to the negative electrode of the comparator, the other end is connected to GND, and an overvoltage protection reference value (i.e., reference voltage) is set by adjusting the resistance values of the resistors R1 and R2. The output of the comparator and the control signal of the DSP are connected to an OR gate, the output of the OR gate is connected to one end of a coil of a relay TR1, and the other end of the coil is connected with 12V.

If the bus voltage is Ui, the sampling signal U is = Ui × R6/(R4 + R5+ R6), the comparator reference voltage Uref = VCC × R2/(R1 + R2), and when U is = Uref, it can be determined as the critical point of overvoltage protection, and the simplified equation Ui = VCC × R2 (R4 + R5+ R6)/[ R6 (R1 + R2) ] sets the overvoltage protection value by adjusting the resistance values of the resistors R1, R2, R3, R4, R5, R6, and when setting the overvoltage protection value, it is necessary to control the power not exceeding the resistors, so as to avoid the over-power damage of the resistors. The VCC power supply may be, but is not limited to, a dc power supply of 12V, 5V, 3.3V, etc.

When a sampling signal (namely, bus voltage obtained by sampling) is smaller than reference voltage, the output of the comparator is at a low level, the output of the OR gate follows the output signal of the DSP control unit, namely, the DSP control unit gives a high/low level, the output of the OR gate U1 is at a high/low level, when the output of the OR gate is at a low level, the two sides of the coil end of the relay TR1 are subjected to voltage difference, so that the switch side is attracted, the bus charging circuit works normally, and when the output of the OR gate is at a low level, the two sides of the coil end of the relay TR1 are not subjected to voltage difference, so that the switch side is disconnected, and the bus charging circuit is disconnected.

When the sampling signal is greater than the reference voltage, the output of the comparator is high level, no matter the DSP control unit gives high/low level, the output of the OR gate U1 is high level, the coil end of the relay TR1 is high level because of both sides, therefore, the switch side is not attracted, the bus circuit is disconnected, and the overvoltage damage caused by overhigh drain-source voltage of the MOS tube is avoided.

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 the same; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art will understand 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 in its corresponding aspects.

Claims

1. A bus voltage protection circuit, comprising:

the sampling circuit is used for sampling bus voltage;

the comparison circuit is connected with the sampling circuit and used for comparing the bus voltage obtained by sampling with the reference voltage and outputting a comparison result signal;

and the relay is connected with the output end of the comparison circuit, and is turned off under the condition that the bus voltage obtained by sampling is greater than the reference voltage according to the comparison result.

2. The protection circuit of claim 1, wherein the sampling circuit comprises: the circuit comprises a first resistor, a second resistor and a third resistor, wherein a first end of the second resistor is connected with the first resistor, and a second end of the second resistor is connected with the third resistor and a first input end of a comparison circuit.

3. The protection circuit of claim 1, wherein a first input of the comparison circuit is coupled to the sampling circuit and a second input of the comparison circuit is coupled to a reference voltage circuit.

4. The protection circuit of claim 3, wherein the reference voltage circuit comprises: the first end of the fourth resistor is connected with a power supply voltage, the second end of the fourth resistor is connected with the second input end of the comparison circuit, the first end of the fifth resistor is grounded, and the second end of the fifth resistor is connected with the second input end of the comparison circuit and the second end of the fourth resistor.

5. The protection circuit of claim 3, wherein the comparison circuit is a comparator, the first input terminal of the comparator is a positive pole of the comparator, and the second input terminal of the comparator is a negative pole of the comparator.

6. The protection circuit according to claim 1, wherein the output of the comparison circuit is connected to the relay through a gate circuit.

7. The protection circuit of claim 6, wherein a first input terminal of the gate circuit is connected to an output terminal of the comparison circuit, a second input terminal of the gate circuit is connected to an output signal of the DSP control unit, and an output terminal of the gate circuit is connected to the first terminal of the relay coil.

8. The protection circuit of claim 7, wherein the second end of the relay coil is connected to a fixed voltage.

9. The protection circuit of claim 6, wherein the gate circuit comprises: or, and gate.

10. Protection circuit according to one of claims 1 to 7, characterized in that it is applied in a photovoltaic air conditioner.