DC bus overvoltage protection circuit

Abstract

The utility model discloses a DC bus overvoltage protection circuit, and mainly relates to the technical field of circuit overvoltage protection. Comprising a voltage sampling module, a voltage comparison module, an alarm isolation module and a control module, the input end of the voltage sampling module is electrically connected with a direct current bus, the output end of the voltage sampling module is electrically connected with the voltage comparison module, and the output end of the voltage comparison module is electrically connected with the input end of the alarm isolation module. The output end of the alarm isolation module is electrically connected with the control module. The beneficial effects of the utility model lie in that the switch-off of the internal circuit can be realized when the voltage of the DC bus is too high, and the circuit elements and the electric equipment can be protected.

Description

Technical Field

[0001] The utility model relates to the technical field of circuit overvoltage protection, in particular to a DC bus overvoltage protection circuit. Background Technique

[0002] In an electronic circuit, various electrical equipment usually uses the grid 220V - 50HZ mains power as an AC input power supply. Due to the diverse application environments, some electrical equipment will convert the alternating current into direct current through a rectifier circuit for use. Since the rectifier circuit is affected by unstable factors such as interference and short circuit, it will cause the bus voltage to suddenly rise, resulting in the circuit components and electrical equipment on the bus being damaged or burned out due to exceeding the rated withstand voltage, which is likely to cause safety accidents.

[0003] Therefore, it is necessary to design a DC bus overvoltage protection circuit for the above problems. Content of the Utility Model

[0004] The purpose of the utility model is to provide a DC bus overvoltage protection circuit, which can realize the function of turning off the internal circuit when the DC bus voltage is too high and protecting circuit components and electrical equipment.

[0005] The utility model to achieve the above object is realized through the following technical solutions:

[0006] It includes a voltage sampling module, a voltage comparison module, an alarm isolation module and a control module. The input end of the voltage sampling module is electrically connected to the DC bus, the output end of the voltage sampling module is electrically connected to the voltage comparison module, the output end of the voltage comparison module is electrically connected to the input end of the alarm isolation module, and the output end of the alarm isolation module is electrically connected to the control module.

[0007] Preferably, the voltage sampling module is provided with a first voltage-dividing resistor and a second voltage-dividing resistor. The first voltage-dividing resistor is provided with a first connection end and a second connection end. The first connection end is the input end of the voltage sampling module and is electrically connected to the DC bus. The second connection end is the output end of the voltage sampling module. The second voltage-dividing resistor is provided with a third connection end and a fourth connection end. The third connection end is electrically connected to the input end of the voltage comparison module, and the fourth connection end is grounded.

[0008] Preferably, the first voltage-dividing resistor and the second voltage-dividing resistor adopt chip resistors.

[0009] Preferably, the voltage comparison module is provided with a first operational amplifier and a second operational amplifier. The non-inverting input terminal of the first operational amplifier is electrically connected to the output terminal of the voltage sampling module. The inverting input terminal of the first operational amplifier is electrically connected to the output terminal of the first operational amplifier. The non-inverting input terminal of the second operational amplifier is electrically connected to the output terminal of the first operational amplifier. The inverting input terminal of the second operational amplifier is electrically connected to the reference voltage source.

[0010] Preferably, the models of the first operational amplifier and the second operational amplifier are TL072 dual-power low-noise input operational amplifiers of Texas Instruments TI.

[0011] Preferably, the input terminal of the alarm isolation module is provided with a fifth connection terminal and a sixth connection terminal. The fifth connection terminal is electrically connected to the output terminal of the voltage comparison module. The sixth connection terminal is grounded. The output terminal of the alarm isolation module is provided with a seventh connection terminal and an eighth connection terminal. The seventh connection terminal is grounded. The eighth connection terminal is connected to the power supply of the control module. The model of the alarm isolation module is ISP817 module of ISOMICRON company.

[0012] Preferably, the control module is specifically a signal processor, and the model is TMS320F28377D dual-core microcontroller of TI company.

[0013] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0014] The overvoltage protection circuit for the DC bus of the present utility model is provided with a voltage-dividing resistor, an integrated operational amplifier, a transistor output optocoupler, and a signal processor, so that when the DC bus voltage is too high, it can not only use the fast signal processing ability of the signal processor to timely turn off the output of the rectifier circuit, but also avoid the signal processor from being impacted by a large voltage through electrical isolation. Brief Description of the Drawings

[0015] Figure 1 is a schematic diagram of the circuit structure of the present utility model.

[0016] Reference numerals shown in the drawings:

[0017] 1. Voltage sampling module; 2. Voltage comparison module; 3. Alarm isolation module; 4. Control module; 5. Rectifier circuit; 6. DC bus. Detailed Embodiment

[0018] The present utility model will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present utility model and not to limit the scope of the present utility model. In addition, it should be understood that after reading the content taught by the present utility model, those skilled in the art can make various changes or modifications to the present utility model, and these equivalent forms also fall within the scope defined by this application.

[0019] In the present invention, terms such as "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "side", "bottom", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only relationship terms determined for the convenience of describing the structural relationship of each component or element of the present invention, and do not specifically refer to any component or element in the present invention, and should not be construed as a limitation to the present invention.

[0020] In the present invention, terms such as "fixed connection", "connected", "connected" should be understood in a broad sense, which means it can be a fixed connection, an integral connection or a detachable connection; it can be directly connected or indirectly connected through an intermediate medium. For those related scientific research or technical personnel in the field, the specific meaning of the above terms in the present invention can be determined according to specific circumstances, and should not be construed as a limitation to the present invention.

[0021] Embodiment:

[0022] As Figure 1 shown, it includes a voltage sampling module, a voltage comparison module, an alarm isolation module and a control module. The input end of the voltage sampling module is electrically connected to the DC bus, the output end of the voltage sampling module is electrically connected to the voltage comparison module, the output end of the voltage comparison module is electrically connected to the input end of the alarm isolation module, and the output end of the alarm isolation module is electrically connected to the control module.

[0023] Among them, the voltage sampling module includes a first voltage dividing resistor R 1 and a second voltage dividing resistor R 2 . The first voltage dividing resistor R 1 includes a first connection terminal and a second connection terminal, and the second voltage dividing resistor R 2 includes a first connection terminal and a second connection terminal; the first voltage dividing resistor and the second voltage dividing resistor are surface mount resistors with a withstand voltage exceeding the DC bus voltage value to avoid being broken down by the high voltage of the DC bus; the resistance values of the first voltage dividing resistor and the second voltage dividing resistor are determined by the rated voltage V D of the DC bus and the reference voltage V 0 , and the determination method is as shown in Equation (1). In the formula, the k value is the overvoltage coefficient of the allowable DC bus voltage, which is set according to the actual situation:

[0024]

[0025] The first voltage-dividing resistor R 1 has its first terminal electrically connected to the DC bus, and its second terminal is electrically connected to the first terminal of the second voltage-dividing resistor R 2 and serves as the output terminal of the voltage sampling module to be electrically connected to the input terminal of the voltage comparison module;

[0026] The second voltage-dividing resistor R 2 has its second terminal grounded. The voltage comparison module includes a first operational amplifier T1 and a second operational amplifier T2. The first operational amplifier T1 includes a non-inverting input terminal, an inverting input terminal, an output terminal, a power supply terminal VCC and VEE. The non-inverting input terminal is electrically connected to the output terminal of the voltage sampling module, the inverting input terminal is electrically connected to the output terminal and is electrically connected to the non-inverting input terminal of the second operational amplifier T2. The power supply terminal VCC is electrically connected to the positive power supply according to the specifications of the operational amplifier, and the power supply connector VEE is electrically connected to the negative power supply or grounded according to the specifications of the operational amplifier;

[0027] The structure of the second operational amplifier T2 is the same as that of the first operational amplifier, but the inverting input terminal is electrically connected to the reference voltage source V 0 and the output terminal of the second operational amplifier T2 serves as the output terminal of the voltage comparison module to be electrically connected to the input terminal of the alarm isolation module.

[0028] The alarm isolation module includes a transistor output optocoupler U1. In this embodiment, the ISP817 module of ISOMICRON company is used. The transistor output optocoupler U1 includes a first input terminal, a second input terminal, a third output terminal and a fourth output terminal. The first input terminal is electrically connected to the output terminal of the voltage comparison module and forms an input loop with the second input terminal. The second input terminal is connected to the ground before electrical isolation. The third output terminal serves as the output terminal of the alarm isolation module and is electrically connected to the power supply VS of the control module and the input terminal of the control module. The third output terminal forms an output loop with the fourth output terminal, and the fourth output terminal is connected to the ground after electrical isolation.

[0029] The control module is mainly composed of a signal processor U2. The signal processor uses a DSP chip or other integrated chips with digital signal processing capabilities. In this utility model, the TMS320F28377D dual-core microcontroller of TI company is used. The signal processor U2 contains multiple groups of input terminals and corresponding multiple groups of output terminals. One group of input terminals and output terminals is selected as part of the DC bus overvoltage protection circuit. The input terminal is electrically connected to the output terminal of the alarm isolation module, and the output terminal is electrically connected to the drive input of the power electronic device of the rectifier circuit. The output of the rectifier circuit determines the voltage value V of the DC bus D .

[0030] In this embodiment, when the DC bus voltage value is less than k*V DWhen the first operational amplifier T1 follows and outputs according to the voltage value sent by the sampling voltage module, since the voltage at the non-inverting input terminal of the second operational amplifier T2 is less than the reference voltage V at the inverting input terminal 0 , the output terminal of the second operational amplifier T2 outputs the voltage VEE, and the input loop of the alarm isolation module is not conducting, realizing that the output of the alarm isolation module is at a high level; the signal processor receiving the high level continues to output the normal trigger signal of the rectifier circuit to ensure the normal output of the DC bus; when the DC bus voltage value exceeds k*V D When the first operational amplifier T1 follows and outputs according to the voltage value sent by the sampling voltage module, since the voltage at the non-inverting input terminal of the second operational amplifier T2 is greater than the reference voltage V at the inverting input terminal 0 , the output terminal of the second operational amplifier T2 outputs the voltage VCC, making the input loop of the alarm isolation module conduct, realizing that the output of the alarm isolation module is at a low level; the signal processor receiving the low level immediately stops the trigger signal of the rectifier circuit and stops the output of the DC bus, realizing the overvoltage protection function of the DC bus.

Claims

1. A DC bus overvoltage protection circuit, characterized in that: It includes a voltage sampling module, a voltage comparison module, an alarm isolation module and a control module, wherein the input end of the voltage sampling module is electrically connected to the DC bus, the output end of the voltage sampling module is electrically connected to the voltage comparison module, the output end of the voltage comparison module is electrically connected to the input end of the alarm isolation module, and the output end of the alarm isolation module is electrically connected to the control module; The voltage sampling module is provided with a first voltage-dividing resistor and a second voltage-dividing resistor, the first voltage-dividing resistor is provided with a first connection end and a second connection end, the first connection end is the input end of the voltage sampling module and is electrically connected to the DC bus, the second connection end is the output end of the voltage sampling module, the second voltage-dividing resistor is provided with a third connection end and a fourth connection end, the third connection end is electrically connected to the input end of the voltage comparison module, and the fourth connection end is grounded; The voltage comparison module is provided with a first operational amplifier and a second operational amplifier, wherein the first operational amplifier has a non-inverting input terminal electrically connected to the output terminal of the voltage sampling module, the first operational amplifier has an inverting input terminal electrically connected to the output terminal of the first operational amplifier, the second operational amplifier has a non-inverting input terminal electrically connected to the output terminal of the first operational amplifier, and the second operational amplifier has an inverting input terminal electrically connected to a reference voltage source; The input end of the alarm isolation module is provided with a fifth connection end and a sixth connection end, the fifth connection end is electrically connected to the output end of the voltage comparison module, the sixth connection end is grounded, and the output end of the alarm isolation module is provided with a seventh connection end and an eighth connection end, the seventh connection end is grounded, and the eighth connection end is connected to the power supply of the control module. The model of the alarm isolation module is the ISP817 module of ISOMICRON.

2. A DC bus overvoltage protection circuit according to claim 1, characterized in that: The first voltage-dividing resistor and the second voltage-dividing resistor are chip resistors.

3. The DC bus overvoltage protection circuit according to claim 1, characterized in that: The first operational amplifier and the second operational amplifier are TL072 dual-power supply low-noise input operational amplifiers produced by Texas Instruments (TI).

4. A DC bus overvoltage protection circuit according to claim 1, characterized in that: The control module is specifically a signal processor, and its model is TMS320F28377D dual-core microcontroller from TI.

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