DC bus voltage detection circuit of inverter

Abstract

The utility model discloses a DC bus voltage detection circuit of an inverter, which comprises a voltage division circuit, an isolation voltage amplification circuit, a differential amplification circuit, a voltage follower circuit and a rectification filter circuit, and is characterized in that the voltage division circuit is connected between the positive electrode and the negative electrode of a DC bus; a voltage signal input pin of the isolation voltage amplification circuit is connected with a voltage division signal output end of the voltage division circuit; two differential analog signal output pins of the isolation voltage amplification circuit are respectively connected with two differential signal input ends of the differential amplification circuit, the input end of the voltage follower circuit is connected with the output end of the differential amplification circuit, and the output end of the voltage follower circuit is connected with the input end of the rectification filter circuit. According to the utility model, the bus voltage detection can be realized by using the simple operational amplifier and the isolation voltage amplifier chip, and the circuit has the advantages of simple structure, low cost and the like.

Description

[Technical field]

[0001] The utility model relates to an inverter, in particular to a DC bus voltage detection circuit of the inverter. [Background Technology]

[0002] The inverter is an important device that converts direct current into alternating current and is widely used in power supply fields such as solar power generation and wind power generation. The bus voltage is one of the judgment bases for inverter startup and is also an important parameter in feedback control.

[0003] The utility model with patent number CN202021956448.8 discloses a three-phase inverter DC bus voltage active isolation detection device, including a resistor voltage-dividing sampling circuit and a DC bus voltage isolation circuit; the resistor voltage-dividing sampling circuit includes a voltage-dividing resistor unit connected to the positive and negative poles of the DC bus and a differential operation circuit for processing the voltage signal output by the voltage-dividing resistor unit; the DC bus voltage isolation circuit is mainly used to separate the output end of the resistor voltage-dividing sampling circuit from the circuit connected to the subsequent stage, to prevent the high-voltage signal at the DC bus end to be detected from interfering with the subsequent stage circuit, and to convert the voltage value output by the differential operation circuit into a voltage value matching the subsequent stage circuit through proportional operation. The active detection device for the DC bus voltage of the inverter uses many active devices such as chips and operational amplifiers, and the devices are susceptible to interference, and there are many anti-interference measures, and the overall cost is high. [Summary of the invention]

[0004] The technical problem to be solved by the utility model is to provide a DC bus voltage detection circuit of an inverter with a simple structure and low cost.

[0005] In order to solve the above technical problems, the technical solution adopted by the utility model is a DC bus voltage detection circuit of an inverter, including a voltage divider circuit, an isolation voltage amplifier circuit, a differential amplifier circuit, a voltage follower circuit and a rectifier filter circuit. The voltage divider circuit is connected to the output end between the positive and negative poles of the DC bus; the voltage signal input pin of the isolation voltage amplifier circuit is connected to the voltage divider signal of the voltage divider circuit; the two differential analog signal output pins of the isolation voltage amplifier circuit are respectively connected to the two differential signal input ends of the differential amplifier circuit, the input end of the voltage follower circuit is connected to the output end of the differential amplifier circuit, and the output end of the voltage follower circuit is connected to the input end of the rectifier filter circuit.

[0006] The DC bus voltage detection circuit described above, the isolation voltage amplifier circuit includes an isolation voltage amplifier chip, the first power input pin of the isolation voltage amplifier chip is connected to a 5V power supply and is grounded through a first capacitor; the second power input pin of the isolation voltage amplifier chip is connected to a 3.3V power supply and is connected to an analog ground through a second capacitor; the voltage signal input pin of the isolation voltage amplifier chip is connected to a voltage signal output end of a voltage divider circuit through a first current limiting resistor and is grounded through a third capacitor, and the third resistor is connected in parallel with the third capacitor; the chip-off input pin of the isolation voltage amplifier chip is grounded and is grounded through a 0Ω resistor; the first ground pin of the isolation voltage amplifier chip is grounded, and the second ground pin is connected to an analog ground.

[0007] The DC bus voltage detection circuit described above, the differential amplifier circuit includes a first operational amplifier, the inverting input terminal of the first operational amplifier is connected to the first differential analog signal output pin of the isolation voltage amplifier chip through the second current limiting resistor, and is connected to the output terminal of the first operational amplifier through the fourth resistor, and the fourth capacitor is connected in parallel with the fourth resistor; the non-inverting input terminal of the first operational amplifier is connected to the second differential analog signal output pin of the isolation voltage amplifier chip through the third current limiting resistor, and is connected to the analog ground through the fifth resistor, and the fifth capacitor is connected in parallel with the fifth resistor.

[0008] The DC bus voltage detection circuit described above, the voltage follower circuit includes a second operational amplifier, the non-inverting input terminal of the second operational amplifier is connected to the output terminal of the first operational amplifier through a fourth current limiting resistor, the inverting input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier; the output terminal of the second operational amplifier is connected to the input terminal of the electric rectifier and filter circuit.

[0009] The DC bus voltage detection circuit described above, the rectifier and filter circuit includes a capacitor and a dual series switching diode, the first end of the capacitor is connected to the output end of the rectifier and filter circuit, and the second end is connected to the analog ground; the anode of the dual series switching diode is connected to the analog ground, the cathode is connected to the 3.3V power supply, and the midpoint is connected to the output end of the rectifier and filter circuit.

[0010] The DC bus voltage detection circuit of the utility model can realize bus voltage detection by using a simple operational amplifier and an isolation voltage amplifier chip, and has the advantages of simple circuit structure, low cost, etc. [Drawings]

[0011] The utility model is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Figure 1 The utility model is a circuit diagram of a DC bus voltage detection circuit of an inverter according to an embodiment of the utility model. [Specific implementation method]

[0012] The DC bus voltage detection circuit of the inverter of the utility model embodiment is as follows Figure 1As shown, it includes a voltage divider circuit, an isolation voltage amplifier circuit, a differential amplifier circuit, a voltage follower circuit, and a rectifier filter circuit. The voltage divider circuit is connected between the positive and negative poles of the DC bus.

[0013] The first power input pin VDD1 of the isolation voltage amplifier circuit (isolation voltage amplifier chip U20, model NS i 1311) is connected to the 5V power supply +5VP, and is grounded to GND through the first capacitor C401. The second power input pin VDD2 of the isolation voltage amplifier circuit is connected to the 3.3V power supply SMCU_3.3V, and is connected to the analog ground AGND through the second capacitor C402. The voltage signal input pin VI N of the isolation voltage amplifier circuit is connected to the voltage divider signal output terminal PFC_FB_S of the voltage divider circuit through the first current limiting resistor R402, and is grounded to GND through the third capacitor C400. The bus voltage is divided by the main board voltage divider resistors R301, R302, R303 and the small board voltage divider resistor R400 to obtain the voltage divider signal PFC_FB_S, which flows into the isolation voltage amplifier chip U20 through the current limiting resistor R402. The SHTDN pin of the isolated voltage amplifier chip is grounded. The SHTDN pin is the chip shutdown input pin, and the high level is effective. Since the input function does not need to be turned off, the pin is low level. For more effective grounding, two 0Ω resistors can be connected between the SHTDN pin and the ground. The first ground pin GND1 of the isolated voltage amplifier circuit is connected to the ground GND, and the second ground pin GND2 is connected to the analog ground AGND.

[0014] The differential amplifier circuit includes a first operational amplifier U21-A, the in-phase input terminal of the first operational amplifier U21-A is connected to the second differential analog signal output pin OUTN of the isolation voltage amplifier circuit through the third current limiting resistor R406, and is connected to the analog ground AGND through the fifth resistor R407, and the fifth capacitor C403 is connected in parallel with the fifth resistor R407. The inverting input terminal of the first operational amplifier U21-A is connected to the first differential analog signal output pin OUTP of the isolation voltage amplifier circuit through the second current limiting resistor R405, and is connected to the output terminal of the first operational amplifier U21-A through the fourth resistor R408, the fourth capacitor C404 is connected in parallel with the fourth resistor R408, and the reverse input is connected to the output through the resistor R408 and the capacitor C404 to form a feedback loop, and the whole constitutes a differential circuit, and its analog output is determined by the gain R408 / R405.

[0015] The voltage follower circuit includes a second operational amplifier U21-B, the in-phase input terminal of the second operational amplifier U21-B is connected to the output terminal of the first operational amplifier U21-A through a fourth current limiting resistor R409, and the inverting input terminal of the second operational amplifier U21-B is connected to the output terminal of the second operational amplifier U21-B.

[0016] The rectifier filter circuit is composed of a capacitor and a dual series switch diode. The first terminal of the capacitor C405 is connected to the filter output VBUS_FBS, and the second terminal is connected to the analog ground AGND; the anode of the dual series switch diode D19 is connected to the analog ground AGND, the cathode is connected to the 3.3V power supply SMCU_3.3V, and the midpoint of the dual series switch diode D19 is connected to the filter output VBUS_FBS.

[0017] When the DC bus voltage detection circuit of the inverter of the embodiment of the utility model is working, the bus voltage is divided by the resistor to obtain the voltage division signal PFC_FB_S, which is input to the voltage signal input pin VI N of the isolation voltage amplifier circuit through the first current limiting resistor R402, and converted into a differential analog signal. The differential analog signal is modulated by the differential amplifier circuit, converted into an analog signal having a corresponding relationship with the bus voltage, and then isolated and followed by the voltage follower circuit. After the voltage follower circuit outputs the follow signal through the rectifier and filter circuit, the filter output VBUS_FBS is connected to the control unit, and the control unit detects the analog signal to obtain the corresponding bus voltage value.

[0018] The DC bus voltage detection circuit of the above embodiment of the utility model can realize the detection of bus voltage by using a simple operational amplifier and an isolation voltage amplifier chip, and has the advantages of simple circuit structure and low cost.

Claims

1. A DC bus voltage detection circuit for an inverter, characterized in that: It includes a voltage divider circuit, an isolation voltage amplifier circuit, a differential amplifier circuit, a voltage follower circuit and a rectifier filter circuit. The voltage divider circuit is connected between the positive and negative poles of the DC bus; the voltage signal input pin of the isolation voltage amplifier circuit is connected to the voltage divider signal output terminal of the voltage divider circuit; the two differential analog signal output pins of the isolation voltage amplifier circuit are respectively connected to the two differential signal input terminals of the differential amplifier circuit, the input terminal of the voltage follower circuit is connected to the output terminal of the differential amplifier circuit, and the output terminal of the voltage follower circuit is connected to the input terminal of the rectifier filter circuit.

2. The DC bus voltage detection circuit according to claim 1, characterized in that: The isolated voltage amplifier circuit comprises an isolated voltage amplifier chip, wherein the first power input pin of the isolated voltage amplifier chip is connected to a 5V power supply and is grounded through a first capacitor; the second power input pin of the isolated voltage amplifier chip is connected to a 3.3V power supply and is connected to an analog ground through a second capacitor; the voltage signal input pin of the isolated voltage amplifier chip is connected to a voltage divider signal of a voltage divider circuit through a first current limiting resistor and is grounded through a third capacitor; the chip-off input pin of the isolated voltage amplifier chip is grounded and is grounded through a 0Ω resistor; the first ground pin of the isolated voltage amplifier chip is grounded, and the second ground pin is connected to an analog ground.

3. The DC bus voltage detection circuit according to claim 1, characterized in that: The differential amplifier circuit includes a first operational amplifier, an inverting input terminal of the first operational amplifier is connected to a first differential analog signal output pin of an isolation voltage amplifier circuit through a second current limiting resistor, and is connected to an output terminal of the first operational amplifier through a fourth resistor, and a fourth capacitor is connected in parallel with the fourth resistor; a non-inverting input terminal of the first operational amplifier is connected to a second differential analog signal output pin of the isolation voltage amplifier circuit through a third current limiting resistor, and is connected to an analog ground through a fifth resistor, and a fifth capacitor is connected in parallel with the fifth resistor.

4. The DC bus voltage detection circuit according to claim 3, characterized in that: The voltage follower circuit includes a second operational amplifier, the in-phase input terminal of the second operational amplifier is connected to the output terminal of the first operational amplifier through a fourth current limiting resistor, the inverting input terminal of the second operational amplifier is connected to the output terminal of the second operational amplifier; and the output terminal of the second operational amplifier is connected to the input terminal of the rectifier and filter circuit.

5. The DC bus voltage detection circuit according to claim 1, characterized in that: The rectifier and filter circuit includes a capacitor and a dual series switch diode. The first end of the capacitor is connected to the output end of the rectifier and filter circuit, and the second end is connected to the analog ground. The anode of the dual series switch diode is connected to the analog ground, the cathode is connected to the 3.3V power supply, and the midpoint is connected to the output end of the rectifier and filter circuit.

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