CN219533365U - Device for detecting state of input end of frequency converter - Google Patents
Device for detecting state of input end of frequency converter Download PDFInfo
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- CN219533365U CN219533365U CN202320353497.XU CN202320353497U CN219533365U CN 219533365 U CN219533365 U CN 219533365U CN 202320353497 U CN202320353497 U CN 202320353497U CN 219533365 U CN219533365 U CN 219533365U
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Abstract
The utility model discloses a device for detecting the state of an input end of a frequency converter, which comprises a signal acquisition circuit, a first signal generation circuit and a second signal generation circuit, wherein the signal acquisition circuit is used for acquiring the current state of each phase of the input end of the frequency converter; the signal analysis circuit is connected with the signal acquisition circuit and is used for judging the state of the input end of the frequency converter according to the first signal; the frequency converter start-stop circuit is used for controlling the start and stop of the frequency converter and generating a second signal at the same time; the signal analysis circuit is connected with the starting and stopping circuit of the frequency converter and is used for starting or stopping operation according to the second signal. The operation of the signal analysis circuit is synchronous with the starting of the frequency converter, so that erroneous judgment can be avoided, and the detection accuracy is improved.
Description
Technical Field
The utility model relates to the field of frequency converters. More particularly, the utility model relates to an apparatus for detecting the state of an input of a frequency converter.
Background
The frequency converter mainly comprises units of rectification, filtering, inversion and the like, and when the three-phase input voltage of the frequency converter is in phase failure, if the frequency converter still operates, the direct current bus capacitor can be charged repeatedly in a large range, and the capacitor is easy to damage. At a lighter load, even if the capacitor is not damaged, the ripple factor of the dc bus voltage will increase compared to normal, causing oscillations in the switching duty cycle of the switching devices of the inverter unit and oscillations in the load current. And when the load is heavy, the rectifying unit may be further damaged, so that the failure probability of the frequency converter is increased. If phase loss occurs when power is transmitted to the frequency converter, the frequency converter is extremely easy to burn out due to single-phase high-current operation.
The existing methods for detecting the input open-phase of the medium-high voltage frequency converter are mainly three.
First kind: the voltage transformer or the current transformer is used for detecting the input voltage or the current signal and is matched with the controller to confirm whether the input high voltage is in open phase or not, but the size of the equipment is larger, and the application range of the frequency converter is affected.
Second kind: through the input leakage current transformer, whether the input high voltage is in the open phase or not can be confirmed by setting the current limit value of the leakage current transformer under a certain condition, but the equipment still has the problem of large volume and is easy to trigger false alarm.
Third kind: and the controller analyzes the waveform of the direct-current voltage pulsation by detecting the waveform of the bus direct-current voltage after the three-phase rectifying circuit and judges whether the input high voltage is in open phase or not. However, when the load is heavy, the fluctuation of the bus voltage is disordered, the analysis of the bus voltage by the controller is easy to be abnormal, and false alarm occurs.
In view of the foregoing, there is a need for a device for detecting the input state of three-phase wires of a frequency converter, which is compact, reliable and stable, so as to accurately determine the phase loss and single-phase abnormality.
Disclosure of Invention
In order to solve at least one or more of the technical problems mentioned above, the present utility model proposes an apparatus for detecting an input state of a frequency converter, comprising: the signal acquisition circuit is used for acquiring the current states of all phases at the input end of the frequency converter to generate a first signal; the signal analysis circuit is connected with the signal acquisition circuit and is used for judging the state of the input end of the frequency converter according to the first signal; the frequency converter start-stop circuit is used for controlling the start and stop of the frequency converter and generating a second signal at the same time; the signal analysis circuit is connected with the starting circuit of the frequency converter and is used for starting or stopping operation according to the second signal.
According to the technical scheme of the utility model, the operation of the signal analysis circuit is synchronous with the starting of the frequency converter, so that erroneous judgment can be avoided, operation resources can be saved, and components of the signal analysis circuit are protected.
Further, the signal acquisition circuit comprises a current transformer switch, a relay, an optical signal generator and an optical signal receiver, wherein a through hole of the current transformer switch is sleeved on a single-phase cable at the input end of the frequency converter; the contacts of the current transformer switch are connected in series with the input loop of the relay; the optical signal generator is connected in series with the output loop of the relay; the optical signal receiver is connected in series with the optical signal receiving circuit; the optical signal receiving circuit is connected with the signal analysis circuit; the optical signal receiver is in optical communication with the optical signal generator.
According to the technical scheme of the utility model, the high-low voltage isolation is realized through the combination of the current transformer switch and the relay, the high-low voltage isolation is further realized through the coupling of the optical signal generator and the optical signal receiver, and the safety is improved. In addition, by arranging an independent optical signal receiving circuit, the stability of the signal is ensured.
Further, the relay is powered by a 12v, 24v or 36v direct current power supply. The safety voltage is adopted, so that the safety attribute is further improved.
Further, a first voltage dividing resistor connected in series with the optical signal generator is arranged in the input loop of the relay.
By providing a first voltage dividing resistor, protection is provided for the optical signal generator.
Further, in the optical signal receiving circuit, a second voltage dividing resistor connected in series with the optical signal receiver is provided.
The second voltage dividing resistor and the optical signal receiver form reasonable resistance value matching, so that voltage signals at two sides of the second voltage dividing resistor float in a stable interval.
Further, the power supply of the optical signal receiving circuit adopts a 3.3v direct current power supply.
After the 3.3v direct current power supply is divided, weak current signals which are easy to perform signal operation are formed, so that the single-phase cable state can be accurately determined.
Further, the second signal controls the start or stop operation of the signal analysis circuit by controlling the on-off of the power supply of the signal analysis circuit.
By controlling the power-on and power-off of the signal analysis circuit, the loss of components of the signal analysis circuit can be reduced.
Further, the device also comprises a low-pass RC filter circuit, and the low-pass RC filter circuit is arranged on the input side of the signal analysis circuit and is used for filtering high-frequency noise.
The operation precision of the signal analysis circuit can be improved and the judgment accuracy of the single-phase cable state can be improved by filtering high-frequency noise in the signal.
Further, the device also comprises a voltage clamping circuit, wherein the voltage clamping circuit is arranged between the signal analysis circuit and the low-pass RC filter circuit.
The clamping circuit provides a stable voltage range for the signal information circuit and protects the internal components.
Further, the frequency converter start-stop circuit and the signal analysis circuit are integrated in the DSP controller.
The DSP controller is used for completing the start-stop control of the frequency converter and the start-stop operation control of the signal analysis circuit, so that the start-stop control and the stop operation control of the signal analysis circuit are synchronous, and the synchronous rate of the control can be improved.
Drawings
The above, as well as additional purposes, features, and advantages of exemplary embodiments of the present utility model will become readily apparent from the following detailed description when read in conjunction with the accompanying drawings. In the drawings, embodiments of the utility model are illustrated by way of example and not by way of limitation, and like reference numerals refer to similar or corresponding parts and in which:
fig. 1 shows a block diagram of an apparatus for detecting the state of an input of a frequency converter;
FIG. 2 shows a schematic diagram of a signal acquisition circuit;
fig. 3 shows a schematic diagram of a signal analysis judgment process.
Detailed Description
The following description of the embodiments of the present utility model will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the utility model. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.
It should be understood that the terms "comprises" and "comprising," when used in this specification and in the claims, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
It is also to be understood that the terminology used in the description of the utility model herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the utility model. As used in the specification and claims, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should be further understood that the term "and/or" as used in the present specification and claims refers to any and all possible combinations of one or more of the associated listed items, and includes such combinations.
As used in this specification and the claims, the term "if" may be interpreted as "when..once" or "in response to a determination" or "in response to detection" depending on the context. Similarly, the phrase "if a determination" or "if a [ described condition or event ] is detected" may be interpreted in the context of meaning "upon determination" or "in response to determination" or "upon detection of a [ described condition or event ]" or "in response to detection of a [ described condition or event ]".
Specific embodiments of the present utility model are described in detail below with reference to the accompanying drawings.
Fig. 1 shows a block diagram of an apparatus for detecting the state of an input of a frequency converter.
As shown in fig. 1, an apparatus for detecting an input state of a frequency converter includes: the signal acquisition circuit is used for acquiring the current states of all phases at the input end of the frequency converter to generate a first signal; the signal analysis circuit is connected with the signal acquisition circuit and is used for judging the state of the input end of the frequency converter according to the first signal; the frequency converter start-stop circuit is used for controlling the start and stop of the frequency converter and generating a second signal at the same time; the signal analysis circuit is connected with the starting circuit of the frequency converter and is used for starting or stopping operation according to the second signal.
The three-phase input end of the frequency converter, each end state comprises a normal state in which current exists in the cable and a phase-lack state in which current does not exist in the cable, the signal acquisition circuit converts the information of whether current exists in the cable into a signal capable of carrying out operation, and the signal is sent to the signal analysis circuit for operation and analysis, so that the input state of the cable is judged.
When the frequency converter is in a stop operation state, one or two phases of the three-phase line can supply power to other modules, for example, the control module only needs 220v voltage, and one phase is used for supplying power. In this case, there is no threat of travel to the frequency converter, and at this time, current detection is performed, and there is a false alarm. The operation of the signal analysis circuit is synchronized with the start-up of the frequency converter, so that erroneous judgment can be avoided. The signal analysis circuit only operates in the operating time period of the frequency converter, so that operation resources can be saved, and components of the signal analysis circuit are protected.
In the utility model, the frequency converter start-stop circuit generates a second signal at the moment of controlling the start-stop of the frequency converter, and sends the second signal to the signal analysis circuit, so that the signal analysis circuit and the frequency converter synchronously operate, thereby realizing the correlation between the detection result and the frequency converter and directly obtaining the detection result affecting the safety of the frequency converter.
The frequency converter start-stop circuit can adopt the existing frequency converter control circuit or can be independently arranged, so that the whole circuit scale is reduced.
In the utility model, the signal analysis circuit has two states, namely an operation state and a dormant state, and the switching of the two states is triggered by the second signal. The second signal contains two aspects, one is that the frequency converter is started and the other is that the frequency converter is stopped.
The implementation of the above two state switching of the signal analysis circuit can be achieved in the prior art, for example, by controlling power-up and power-down. The second signal can be an electric signal for logic judgment or a mechanical triggering action, and the two modes have implementation modes in the prior art, so long as the method can complete triggering of two state switching of the signal analysis circuit without limiting the specific generation and transmission processes of the second signal.
In the utility model, the signal acquisition circuit is independently arranged on each phase cable of the frequency converter, so that three signal acquisition circuits are arranged, the signal analysis circuit can be shared among the signal acquisition circuits, the signal analysis circuit can be independently arranged, the signal analysis circuit is preferably shared, and the circuit can be simplified to realize the miniaturization of the device.
Fig. 2 shows a schematic diagram of a signal acquisition circuit.
As shown in fig. 2, taking signal acquisition of a certain phase as an example, the signal acquisition circuit comprises a current transformer switch 11, a relay 12, an optical signal generator 13 and an optical signal receiver 14, wherein a through hole of the current transformer switch 11 is sleeved on a single-phase cable at the input end of the frequency converter; the contacts of the current transformer switch are connected in series in the input loop of the relay 12; the optical signal generator 13 is connected in series with the output loop of the relay 12; the optical signal receiver 14 is connected in series with an optical signal receiving circuit; the optical signal receiving circuit is connected with the signal analysis circuit; the optical signal receiver 14 is connected in optical communication with the optical signal generator 13.
The current transformer switch is also called a current induction switch or a current switch sensor, and generally comprises a transformer coil, a switch circuit, a protective shell, a wiring terminal and the like. A portion of the mutual inductance coil forms a through hole to accommodate the cable being tested. When detecting that current exists in the cable, the connection terminals of the switch circuit are connected or disconnected. The wiring terminal of the switch circuit is also called a contact and is used for being externally connected with other circuits so as to control the on-off of the other circuits.
The relay is a device for controlling the mechanical contact to be on or off by utilizing electromagnetic effect, for example, the coil with iron core is electrified, the coil current generates magnetic field, and the magnetic field attracts the armature to act to turn on or off the contact. Typically comprising an input loop, which is a loop connected to a power source and a control coil generating a magnetic field, and an output loop.
In the utility model, the contacts of the current transformer switch are connected in series in the input loop of the relay so as to realize the control of the on-off of the input loop of the relay.
In the output loop of the relay, a power supply and an optical signal generator are connected in series to form an optical signal transmitting circuit. When the output loop of the relay is conducted, the power supply supplies power to the optical signal generator, and the optical signal generator converts the electric signal into an optical signal and transmits the optical signal outwards.
The optical signal receiving circuit comprises a power supply and an optical signal receiver, the optical signal receiver 14 is coupled with the optical signal generator 13 to realize optical communication, receives the optical signal from the optical signal generator 13, converts the optical signal into an electric signal, and transmits the electric signal to the signal analysis circuit for operation and judgment.
The optical signal generator and the optical signal receiver can be selected from the existing or future optical communication elements according to the requirements, and the utility model is not limited.
According to the utility model, the current transformer switch is adopted to detect the current in the cables of each phase, so that the isolation between high voltage and low voltage can be realized. Isolation between high and low voltages is further achieved by employing optical communication between the optical signal generator and the optical signal receiver. The dual isolation structure of the utility model protects the safety of the signal analysis circuit. The power supplies of the optical signal transmitting circuit and the optical signal receiving circuit can be mutually independent, so that the signal strength of the optical signal receiving circuit can be ensured to be set according to the requirement of the signal analysis circuit, the influence of a high-voltage side is avoided, and the stability of a detection result is improved.
According to one embodiment of the utility model, the relay is powered by a 12v, 24v or 36v dc power supply. Preferably using a 24v power supply.
In the utility model, the input loop and the output loop of the relay can be powered by different power supplies, and can also be powered by the same power supply. Because in the present utility model the use of a relay is not a traditional small current controlled high current application, but rather an electrically isolating effect is achieved. The same power supply is adopted for supplying power, so that the volume of the equipment can be reduced, and the miniaturization is realized.
As shown in fig. 2, according to an embodiment of the present utility model, a first voltage dividing resistor R03 connected in series with the optical signal generator 13 is provided in the input circuit of the relay.
The first voltage dividing resistor R03 realizes protection of the optical signal generator, and may be provided in two or more, and when two or more are provided, it is preferable to be provided on both sides of the optical signal generator, respectively.
As shown in fig. 2, the optical signal receiving circuit is provided with a second voltage dividing resistor R05 connected in series with the optical signal receiver 14.
After the optical signal receiver 14 receives the optical signal, the optical signal receiver 14 is saturated and turned on, and the potential of the collector electrode changes from the high level to the level. The second voltage dividing resistor R05 has the following functions: the circuit is limited by current to realize the level change.
According to one embodiment of the utility model, the power supply of the optical signal receiving circuit adopts a 3.3v direct current power supply.
According to one embodiment of the utility model, the second signal controls the start or stop of the signal analysis circuit by controlling the on-off of the power supply of the signal analysis circuit.
The signal analysis circuit can be implemented by adopting the existing operation chip, such as a DSP chip to load the corresponding operation program.
As shown in fig. 2, the apparatus for detecting the state of the input end of the frequency converter further includes a low-pass RC filter circuit, which is disposed at the input side of the signal analysis circuit, for filtering high-frequency noise, according to an embodiment of the present utility model.
The low-pass filter circuit is composed of a resistor R06 and a capacitor C01, has a cutoff frequency f=1/2 pi RC, and ensures that high-frequency signals are filtered out by selecting proper capacitance resistance values and setting the cutoff frequency, the low-frequency signals can pass through, and the operation accuracy of the signals is improved.
According to one embodiment of the utility model, the means for detecting the state of the input of the frequency converter further comprises a voltage clamp, i.e. built up by a clamp diode D01, said voltage clamp being arranged between said signal analysis circuit and said low-pass RC filter circuit.
The frequency converter start-stop circuit and the signal analysis circuit are integrated in the DSP controller. As shown in FIG. 2, if the 3.3V voltage supply of the resistor at the upper end of the photoelectric receiver changes due to abnormal power supply line, when the voltage is higher than 3.3V or lower than 0V, the clamping circuit can control the potential of IO of the DSP to 0-3.3V, so that the DSP is ensured not to be damaged due to abnormal power supply of other power supplies.
When the frequency converter is started, the DSP can control the driving module of the frequency converter to control the inverter circuit, so that the frequency converter is started. After the DSP sends out a driving signal, 50ms later or in the excitation stage of the frequency converter, the collected state of the switch of the input current transformer is analyzed to confirm whether the input power supply of the frequency converter is in a phase failure state. If the IO of the DSP corresponding to the detection of one phase cable is low level, the phase is judged to be in a phase failure.
Fig. 3 shows a schematic diagram of a signal analysis judgment process.
As shown in fig. 3, after the signal analysis circuit is powered on, the level signals of 3 IO ports are collected and received, the received level signals are judged to be high level or low level, and the cable state corresponding to each level signal is judged based on the preset. For example, when the level signal corresponding to a certain phase cable is low, it is determined that the phase is absent, and when the level signals corresponding to three phase cables are high, it is determined that the three-phase power supply state is normal.
The utility model protects the safety of the signal analysis circuit through the double isolation structure. The power supplies of the optical signal transmitting circuit and the optical signal receiving circuit can be mutually independent, so that the signal strength of the optical signal receiving circuit can be ensured to be set according to the requirement of the signal analysis circuit, the influence of a high-voltage side is avoided, and the stability of a detection result is improved. The operation of the signal analysis circuit is synchronous with the starting of the frequency converter, so that erroneous judgment can be avoided, and the detection accuracy is improved.
While various embodiments of the present utility model have been shown and described herein, it will be obvious to those skilled in the art that such embodiments are provided by way of example only. Numerous modifications, changes, and substitutions will occur to those skilled in the art without departing from the spirit and scope of the utility model. It should be understood that various alternatives to the embodiments of the utility model described herein may be employed in practicing the utility model. The appended claims are intended to define the scope of the utility model and are therefore to cover all equivalents or alternatives falling within the scope of these claims.
Claims (10)
1. An apparatus for detecting an input state of a frequency converter, comprising:
the signal acquisition circuit is used for acquiring the current states of all phases at the input end of the frequency converter to generate a first signal;
the signal analysis circuit is connected with the signal acquisition circuit and is used for judging the states of all phases at the input end of the frequency converter according to the first signal;
the frequency converter start-stop circuit is used for controlling the start and stop of the frequency converter and generating a second signal at the same time;
the signal analysis circuit is connected with the starting circuit of the frequency converter and is used for starting or stopping operation according to the second signal.
2. The apparatus of claim 1, wherein the device comprises a plurality of sensors,
the signal acquisition circuit comprises a current transformer switch, a relay, an optical signal generator and an optical signal receiver,
the through hole of the current transformer switch is sleeved on the single-phase cable at the input end of the frequency converter;
the contacts of the current transformer switch are connected in series with the input loop of the relay;
the optical signal generator is connected in series with the output loop of the relay;
the optical signal receiver is connected in series with the optical signal receiving circuit;
the optical signal receiving circuit is connected with the signal analysis circuit;
the optical signal receiver is in optical communication with the optical signal generator.
3. The apparatus of claim 2, wherein the device comprises a plurality of sensors,
the relay is powered by a 12v, 24v or 36v direct current power supply.
4. The apparatus of claim 2, wherein the device comprises a plurality of sensors,
and a first voltage dividing resistor connected in series with the optical signal generator is arranged in an input loop of the relay.
5. The apparatus of claim 2, wherein the device comprises a plurality of sensors,
the optical signal receiving circuit is provided with a second voltage dividing resistor connected in series with the optical signal receiver.
6. The apparatus of claim 5, wherein the device comprises a plurality of sensors,
the power supply of the optical signal receiving circuit adopts a 3.3v direct current power supply.
7. The apparatus of claim 1, wherein the device comprises a plurality of sensors,
the connection mode of the signal analysis circuit and the frequency converter start-stop circuit is set to enable the second signal to control the start or stop operation of the signal analysis circuit by controlling the on-off of a power supply of the signal analysis circuit.
8. The apparatus of claim 1, wherein the device comprises a plurality of sensors,
the low-pass RC filter circuit is arranged on the input side of the signal analysis circuit and is used for filtering high-frequency noise.
9. The apparatus of claim 8, wherein the device comprises a plurality of sensors,
the low-pass RC filter circuit further comprises a voltage clamping circuit, wherein the voltage clamping circuit is arranged between the signal analysis circuit and the low-pass RC filter circuit.
10. The apparatus of claim 1, wherein the device comprises a plurality of sensors,
the frequency converter start-stop circuit and the signal analysis circuit are integrated in the DSP controller.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320353497.XU CN219533365U (en) | 2023-02-28 | 2023-02-28 | Device for detecting state of input end of frequency converter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320353497.XU CN219533365U (en) | 2023-02-28 | 2023-02-28 | Device for detecting state of input end of frequency converter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN219533365U true CN219533365U (en) | 2023-08-15 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202320353497.XU Active CN219533365U (en) | 2023-02-28 | 2023-02-28 | Device for detecting state of input end of frequency converter |
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| Country | Link |
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| CN (1) | CN219533365U (en) |
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- 2023-02-28 CN CN202320353497.XU patent/CN219533365U/en active Active
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