CN210128992U - Alternating current acquisition circuit applied to three-phase grid-connected inverter - Google Patents
Alternating current acquisition circuit applied to three-phase grid-connected inverter Download PDFInfo
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- CN210128992U CN210128992U CN201920718364.1U CN201920718364U CN210128992U CN 210128992 U CN210128992 U CN 210128992U CN 201920718364 U CN201920718364 U CN 201920718364U CN 210128992 U CN210128992 U CN 210128992U
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Abstract
The utility model provides an alternating current acquisition circuit applied to a three-phase grid-connected inverter, which comprises a Hall current sensor, a sampling resistor, a filter capacitor, an integrating circuit, a voltage bias circuit, a voltage follower and a voltage clamper; the utility model has the advantages that the current signal distortion degree collected by the high-precision alternating current collecting circuit is small, the inversion result can be observed by matching with an oscilloscope, the waveform of the inversion current can be visually obtained, and when the harmonic wave is large, the inverter is ensured to work in the safe current range; the utility model discloses alternating current acquisition circuit also can be used to in other alternating current acquisition systems, convenient and reliable.
Description
Technical Field
The utility model relates to a power electronics field especially relates to an alternating current acquisition circuit for three-phase grid-connected inverter.
Background
With the urgent development of green energy-saving energy in the current society, the three-phase grid-connected inverter has obvious effects in energy conservation, emission reduction and energy recycling. The three-phase grid-connected inverter is widely applied in the power electronic industry, in an inversion grid-connected system, a grid-connected current signal is very important for a control system, and the quality of grid-connected current determines the inversion efficiency of the system. Accurate alternating current signals need to be acquired, such as establishment of a grid-connected inverter mathematical model, PI regulation of closed-loop control, guarantee that grid-connected current meets grid-connected conditions and the like. In addition, the fact that the grid-connected current is in a controllable range is very critical to system safety.
Disclosure of Invention
The utility model provides a be applied to three-phase grid-connected inverter's alternating current acquisition circuit solves the problem among the prior art.
In order to achieve the purpose of the invention, the utility model provides a scheme as follows:
an alternating current acquisition circuit applied to a three-phase grid-connected inverter comprises a Hall current sensor, a sampling resistor, a filter capacitor, an integrating circuit, a voltage bias circuit, a voltage follower and a voltage clamper; three wiring terminals of the Hall current sensor are respectively connected with +15V, -15V and a measurement output end M; the output obtained by the measuring output end M is a current signal, the current signal passes through a sampling resistor R1 to obtain a voltage signal, and the voltage signal is connected with a filter capacitor C1 in parallel with a sampling resistor R1; the integrating circuit comprises an operational amplifier U1A, a resistor R2, a resistor R3, a resistor R4 and a capacitor C2, a voltage signal after passing through a sampling resistor R1 is used as an input voltage of the operational amplifier U1A, the input voltage is added to an inverting input end of the operational amplifier U1A through a resistor R2, the capacitor C2 is arranged between an output end and the inverting input end of an operational amplifier U1A, the resistor R4 is connected to a capacitor C2 in parallel, and the resistor R3 is connected to the homodromous input end of the operational amplifier U1A; the voltage bias circuit comprises a resistor R5, a resistor R6 and a-3.3V power supply, wherein the-3.3V power supply is connected with the resistor R6, the resistor R5 is connected with the output end of the operational amplifier U1A, and the resistor R6 is connected with a resistor R5 in parallel; the voltage follower comprises an operational amplifier U1B, a resistor R7 and a resistor R8, wherein the inverting input end of the operational amplifier U1B is connected with the resistor R5, a resistor R8 is arranged between the output end and the inverting input end of the operational amplifier U1B, and the resistor R7 is connected with the homodromous input end of the operational amplifier U1A; the voltage clamp comprises a resistor R9, a diode D1, a diode D2 and a +3.3V power supply, wherein the resistor R9 is connected with the output end of an operational amplifier U1B, a resistor R9 is connected with a diode D1 and a diode D2, the diode D1 is connected with the +3.3V power supply, and a diode D2 is grounded.
Furthermore, the type of the Hall current sensor is a Hall current sensor HNC-50 LA.
Compared with the prior art, the invention has the beneficial effects that:
the utility model has the advantages that the current signal distortion degree collected by the high-precision alternating current collecting circuit is small, the inversion result can be observed by matching with an oscilloscope, the waveform of the inversion current can be visually obtained, and when the harmonic wave is large, the inverter is ensured to work in the safe current range; the utility model discloses alternating current acquisition circuit also can be used to in other alternating current acquisition systems, convenient and reliable.
Drawings
Fig. 1 is a circuit diagram of the present invention;
fig. 2 is a working schematic diagram of the circuit of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings. Wherein like elements in different embodiments are numbered with like associated elements. In the following description, numerous details are set forth in order to provide a better understanding of the present application. However, those skilled in the art will readily recognize that some of the features may be omitted or replaced with other elements, materials, methods in different instances.
In the design of the three-phase grid-connected inverter, the alternating current component plays a key role in establishing a mathematical model of the three-phase grid-connected inverter system. In addition, a system generally applying a direct current control strategy adopts a voltage outer ring and a current inner ring to form a double closed-loop control structure, and the current ring is used as an inner ring of the double closed-loop structure and has the effect of inhibiting load disturbance. In an inversion grid-connected system, grid-connected current and grid voltage have the same frequency and phase, which are necessary conditions for ensuring that the system has a high power factor, so that the acquisition of an accurate three-phase grid-connected current signal is very important. The current signal distortion degree that the current acquisition circuit of high accuracy gathered is little, can cooperate oscilloscope to observe the contravariant result, can directly perceivedly obtain the wave form of contravariant current, when the harmonic is great, further improve the system, ensure that the dc-to-ac converter works in safe current range. The utility model discloses alternating current acquisition circuit also can be used to in other alternating current acquisition systems, convenient and reliable.
The alternating current detection circuit is shown in fig. 1, a Hall current sensor HNC-50LA is selected for collecting alternating current signals, and the electrical parameters of the alternating current detection circuit are shown in table 1. The sensor utilizes the principle of electromagnetic induction, does not need to be connected into a circuit, only needs to pass a current lead to be measured through the module input through hole, can sample from the output end M to measure the size of induced current, and has high measurement precision, convenient use, safety and reliability.
TABLE 1
Three terminals of the Hall current sensor HNC-50LA are +15V, -15V and a measurement output end M respectively.
The output obtained by the Hall current sensor HNC-50LA is a current signal, and a voltage signal is obtained after R1 sampling resistance, and is in direct proportion to the grid-connected current. C1 is a filter capacitor which is connected with R1 in parallel and filters harmonic components output by the sensor.
The operational amplifier U1A, R2, R3, R4 and C2 form an integrating circuit for eliminating offset voltage. The voltage signal after passing through the sampling resistor R1 is used as the input voltage of the operational amplifier, is added to the inverting input end of the integrated operational amplifier through R2, and is led back to a depth negative feedback between the output end and the inverting input end through a capacitor C2; in order to balance the resistances of the two input ends of the integrated operational amplifier to the ground, the resistance R3 of the non-inverting input end is R2; in order to prevent the low-frequency signal from being too high in gain, a resistor R4 is connected in parallel to the capacitor C2 for limitation. In addition, in an actual integrator, due to the fact that an operational amplifier inevitably has bias voltage, although the bias voltage is low, the capacitor is charged and discharged, the capacitor is saturated after a long time, and the parallel resistor can provide a discharge loop for the capacitor and does not saturate.
Assuming that the voltage across the sampling resistor R1 is Ui and the voltage at the output end of the operational amplifier is Uo, the relationship between Ui and Uo is:
in the formula UO (t)1) For integrating the output voltage at the start of the integration, the final value of the integration is t2The output voltage at the moment.
The voltage bias circuit is composed of R5, R6 and-3.3V power supplies. Because the voltage which can be accepted by the DSP is 0-3.3V, and the voltage is still an alternating current signal after passing through the integrator, and positive and negative voltages exist, a bias circuit is needed to pull the voltage down to a negative half shaft.
The operational amplifier U1B and the resistors R7 and R8 form an inverting voltage follower, and the inverting voltage follower is equivalent to an open circuit to a preceding stage due to the characteristics of high input impedance and low output impedance, and plays a role in isolating in a circuit. R9 is a current limiting resistor of 1.8K.
The D1, D2 and +3.3V power supply form a voltage clamping and limiting circuit to ensure that the voltage is between 0-3.3V that the DSP can receive.
For example, fig. 2 is a software flow chart of a current acquisition signal part in a three-phase grid-connected inverter, a system needs to be initialized, and an acquired current signal is subjected to a/D conversion to complete a control algorithm of the inverter.
The present invention has been described in terms of specific examples, which are provided to aid understanding of the invention and are not intended to be limiting. For a person skilled in the art to which the invention pertains, several simple deductions, modifications or substitutions may be made according to the idea of the invention.
Claims (2)
1. An alternating current acquisition circuit applied to a three-phase grid-connected inverter is characterized by comprising a Hall current sensor, a sampling resistor, a filter capacitor, an integrating circuit, a voltage bias circuit, a voltage follower and a voltage clamper; three wiring terminals of the Hall current sensor are respectively connected with +15V, -15V and a measurement output end M; the output obtained by the measuring output end M is a current signal, the current signal passes through a sampling resistor R1 to obtain a voltage signal, and the voltage signal is connected with a filter capacitor C1 in parallel with a sampling resistor R1; the integrating circuit comprises an operational amplifier U1A, a resistor R2, a resistor R3, a resistor R4 and a capacitor C2, a voltage signal after passing through a sampling resistor R1 is used as an input voltage of the operational amplifier U1A, the input voltage is added to an inverting input end of the operational amplifier U1A through a resistor R2, the capacitor C2 is arranged between an output end and the inverting input end of an operational amplifier U1A, the resistor R4 is connected to a capacitor C2 in parallel, and the resistor R3 is connected to the homodromous input end of the operational amplifier U1A; the voltage bias circuit comprises a resistor R5, a resistor R6 and a-3.3V power supply, wherein the-3.3V power supply is connected with the resistor R6, the resistor R5 is connected with the output end of the operational amplifier U1A, and the resistor R6 is connected with a resistor R5 in parallel; the voltage follower comprises an operational amplifier U1B, a resistor R7 and a resistor R8, wherein the inverting input end of the operational amplifier U1B is connected with the resistor R5, a resistor R8 is arranged between the output end and the inverting input end of the operational amplifier U1B, and the resistor R7 is connected with the homodromous input end of the operational amplifier U1A; the voltage clamp comprises a resistor R9, a diode D1, a diode D2 and a +3.3V power supply, wherein the resistor R9 is connected with the output end of an operational amplifier U1B, a resistor R9 is connected with a diode D1 and a diode D2, the diode D1 is connected with the +3.3V power supply, and a diode D2 is grounded.
2. The alternating current acquisition circuit applied to the three-phase grid-connected inverter as claimed in claim 1, wherein the type of the Hall current sensor is a Hall current sensor HNC-50 LA.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920718364.1U CN210128992U (en) | 2019-05-17 | 2019-05-17 | Alternating current acquisition circuit applied to three-phase grid-connected inverter |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201920718364.1U CN210128992U (en) | 2019-05-17 | 2019-05-17 | Alternating current acquisition circuit applied to three-phase grid-connected inverter |
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| CN210128992U true CN210128992U (en) | 2020-03-06 |
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| CN201920718364.1U Expired - Fee Related CN210128992U (en) | 2019-05-17 | 2019-05-17 | Alternating current acquisition circuit applied to three-phase grid-connected inverter |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112462258A (en) * | 2020-11-06 | 2021-03-09 | 珠海格力电器股份有限公司 | Motor terminal voltage detection method, device and circuit and air conditioning system |
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2019
- 2019-05-17 CN CN201920718364.1U patent/CN210128992U/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112462258A (en) * | 2020-11-06 | 2021-03-09 | 珠海格力电器股份有限公司 | Motor terminal voltage detection method, device and circuit and air conditioning system |
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| CF01 | Termination of patent right due to non-payment of annual fee |
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| CF01 | Termination of patent right due to non-payment of annual fee |