CN219842536U - Frequency converter power unit short circuit monitoring loop - Google Patents
Frequency converter power unit short circuit monitoring loop Download PDFInfo
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- CN219842536U CN219842536U CN202320802149.6U CN202320802149U CN219842536U CN 219842536 U CN219842536 U CN 219842536U CN 202320802149 U CN202320802149 U CN 202320802149U CN 219842536 U CN219842536 U CN 219842536U
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- 238000012544 monitoring process Methods 0.000 title claims abstract description 46
- 239000003990 capacitor Substances 0.000 abstract description 4
- 238000000034 method Methods 0.000 abstract 1
- 238000005070 sampling Methods 0.000 description 3
- 238000010586 diagram Methods 0.000 description 2
- 230000009897 systematic effect Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000007405 data analysis Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
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Abstract
The utility model relates to the technical field of electrical design, and particularly discloses a frequency converter power unit short circuit monitoring loop, which comprises a frequency converter power unit circuit and an inductor, wherein the inductor comprises an inductor L 1 And inductance L 2 Inductance L 1 And inductance L 2 Connected to the power unit circuit of the frequency converter, the inductor L 1 Parallel voltage monitoring module I, inductor L 2 A second parallel voltage monitoring module; the frequency converter power unit circuit is provided with a positive direct current bus and a negative direct current bus, and an inductor L is connected in series on the positive direct current bus 1 Series inductance L on negative DC bus 2 The method comprises the steps of carrying out a first treatment on the surface of the The inductor additionally arranged on the direct current bus not only can filter ripple current on the direct current bus and smooth direct current waveform, but also can properly inhibit large short-circuit current flowing through the system when short circuit occurs, and furthest protects the frequency converter system from damage; the inductor can also form a clamping loop of the direct current bus with devices such as a capacitor C and the like, so that the voltage stability at two ends of the direct current bus is better controlled.
Description
Technical Field
The utility model relates to the technical field of electrical design, in particular to a short circuit monitoring loop of a power unit of a frequency converter.
Background
Frequency converter transmission systems are particularly important in the industry, and the power units are the main parts of the main circuit of the high-voltage frequency converter. The power unit is a high voltage inverter component that rectifies, filters, inverts using power electronics. Whether the normal work of the power unit of the frequency converter directly influences the service life of the frequency converter equipment, at present, a loop for short circuit monitoring is not carried out on the power unit of the frequency converter, the specific position of the short circuit fault of the frequency converter cannot be directly judged, the protection response of a control system is too slow, systematic damage of the frequency converter can be caused, and a frying event is easy to occur. Therefore, a new short circuit monitoring loop of the power unit of the frequency converter is required to be provided, which is used for monitoring the working condition of the power unit of the frequency converter in real time, and can effectively prevent the short circuit of the power unit from occurring.
Disclosure of Invention
Aiming at the problems existing in the prior art, the utility model aims to provide a short circuit monitoring loop of a power unit of a frequency converter.
The technical scheme adopted for solving the technical problems is as follows: a frequency converter power unit short circuit monitoring loop comprises a frequency converter power unit circuit and an inductor, wherein the inductor comprises an inductor L 1 And inductance L 2 Inductance L 1 And inductance L 2 Connected to the power unit circuit of the frequency converter, the inductor L 1 Parallel voltage monitoring module I, inductor L 2 And a second parallel voltage monitoring module.
Specifically, the frequency converter power unit circuit is provided with a positive direct current bus and a negative direct current bus, and an inductor L is connected in series on the positive direct current bus 1 Series inductance L on negative DC bus 2 。
Specifically, the first voltage monitoring module monitors the inductance L 1 Voltage value U of (2) 1 Second monitoring inductance L of voltage monitoring module 2 Voltage value U of (2) 2 Voltage value U 1 And a voltage value U 2 And feeding back to the control system to judge whether the frequency converter power unit circuit has short circuit fault.
Specifically, the frequency converter power unit circuit is also provided with a three-phase electric interface phase line U, a phase line V and a phase line W.
The utility model has the following beneficial effects:
the short-circuit monitoring loop of the frequency converter power unit designed by the utility model has simple structure, safety and reliability;
1. the inductor additionally arranged on the direct current bus not only can filter ripple current on the direct current bus and smooth direct current waveform, but also can properly inhibit large short-circuit current flowing through the system when short circuit occurs, and the frequency converter system is protected from being damaged to the greatest extent;
2. the inductor can also form a clamping loop of the direct current bus with devices such as a capacitor C and the like, so that the voltage stability at two ends of the direct current bus is better controlled.
Drawings
Fig. 1 is a schematic circuit diagram of a frequency converter power cell short circuit monitoring loop.
FIG. 2 shows the flow through inductance L 1 And inductance L 2 Is a schematic diagram of the current change rate of (a).
In the figure: 1-a first voltage monitoring module; 2-a second voltage monitoring module.
Detailed Description
The technical solutions in the embodiments of the present utility model will be clearly and completely described in further detail below with reference to the accompanying drawings in the embodiments of the present 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.
As shown in FIG. 1, a frequency converter power unit short circuit monitoring loop comprises a frequency converter power unit circuit and an inductor, wherein the inductor comprises an inductor L 1 And inductance L 2 Inductance L 1 And inductance L 2 Connected to the power unit circuit of the frequency converter, the inductor L 1 Parallel voltage monitoring module 1, inductor L 2 Parallel voltageAnd a second monitoring module 2. The frequency converter power unit circuit is provided with a positive direct current bus and a negative direct current bus, and an inductor L is connected in series on the positive direct current bus 1 Series inductance L on negative DC bus 2 . The frequency converter power unit circuit is also provided with a three-phase electric interface phase line U, a phase line V and a phase line W.
Voltage monitoring module 1 monitoring inductance L 1 Voltage value U of (2) 1 Two 2 monitoring inductances L of voltage monitoring module 2 Voltage value U of (2) 2 Voltage value U 1 And a voltage value U 2 The feedback is sent to the control system to judge whether the frequency converter power unit circuit has short circuit fault, and the loop has simple structure, safety and reliability.
The working principle of the utility model is as follows:
the short circuit monitoring loop mainly consists of an inductor L 1 Inductance L 2 And a voltage monitoring loop.
(1) When the power unit works normally, the current flows through the inductor L 1 And inductance L 2 The current change rate of (a) is not large (k as in FIG. 2 1 ) The voltage monitoring module monitors the inductance L 1 And inductance L 2 Voltage U at both ends 1 And U 2 Lower than the set threshold |u|;
(2) when the power unit has short-circuit fault, the current flows through the inductor L 1 And inductance L 2 The current change rate of (e.g. k in fig. 2) increases abruptly 2 ) The voltage monitoring module monitors the inductance L 1 And inductance L 2 Voltage U at both ends 1 And U 2 Is higher than a set threshold |u|;
(3) if the duration of the monitored voltage exceeds a time threshold T (T in FIG. 2), the control system can determine that the power unit has a short circuit fault, and the system operates the protection device to prevent the occurrence of a frying event.
Wherein:
k＝di/dt
k 1 ＝di 1 /dt
k 2 ＝di 2 /dt
U 1 ＝L 1 *k 1 ＝L 1 *(di 1 /dt)
U 2 ＝L 2 *K 2 ＝L 2 *(di 2 /dt)
|U|＝L*k＝L*(di/dt)
T＝t 2 -t 1
k: inductance L 1 And inductance L 2 A change rate threshold of the medium current (set to be constant according to the actual);
k 1 : inductance L 1 Real-time rate of change of medium current;
K 2 : inductance L 2 Real-time rate of change of medium current;
U 1 : inductance L 1 The voltage at two ends in real time;
U 2 : inductance L 2 The voltage at two ends in real time;
u: inductance L 1 And inductance L 2 A two-terminal voltage threshold (set to a constant according to reality);
t: a time threshold (set to a constant according to the actual) is set.
The sampling time period of the voltage monitoring modules at the two ends of the inductor is deltat (delta T in fig. 2), the time deltat is reasonably configured with a duration time threshold value T, in the time threshold value T, enough voltage sampling sample quantity beta is ensured, and through large sample data analysis, it is judged that the power unit does have short circuit fault in the duration time T, but no accidental system overcurrent event occurs.
Wherein:
Δt＝t 3 -t 1
β＝T/Δt＝(t 2 -t 1 )/(t 3 -t 1 )
Δt: detecting time frequency of voltage at two ends of the inductor;
beta: the number of samples of the voltage sample in the time threshold T.
The time threshold T is not set too high, when a short-circuit fault of the power unit occurs, a momentary short-circuit heavy current passes through the power unit, and if the time threshold T is set too long, the protection reaction of the control system is too slow, and the systematic damage of the frequency converter can be caused.
For facilitating the occurrence of short-circuitsWhen the power unit works normally, the system controls the flash frequency of the diode to be f 1 When the power unit works normally, the system controls the flash frequency f of the diode 2 Hertz (wherein f) 2 >>f 1 ) When the high-frequency flickering of the light-emitting diode of the voltage monitoring module is found, the machine should be stopped for inspection in time.
The short circuit monitoring loop does not select the conventional devices such as a current transformer, and the like, judges the current short circuit condition by monitoring the secondary side numerical value of the current transformer, and adopts a small number of electronic components to complete the short circuit monitoring function.
The inductor additionally arranged on the direct current bus not only can filter ripple current on the direct current bus and smooth direct current waveform, but also can properly inhibit large short-circuit current flowing through the system when short circuit occurs, and furthest protects the frequency converter system from damage.
The inductor can also form a clamping loop of the direct current bus with devices such as a capacitor C and the like, so that the voltage stability at two ends of the direct current bus is better controlled.
Description: (1) the inductance value L of the series inductor in the loop is required to be designed in detail through the whole system, so that the possibility of electromagnetic resonance between the inductor and devices such as a capacitor in the loop of the system is eliminated, and the resonance frequency is avoided.
(2) Voltage monitoring module data sampling period frequency delta t at two ends of inductor and inductor L 1 And inductance L 2 The voltage threshold value |U| and the delay time threshold value T at the two ends are reasonably set according to actual conditions, and the condition that the system is in missing report or false report caused by too large or too small setting is prevented.
(3) Inductance L connected in series in direct current positive and negative buses 1 And inductance L 2 The same selection should be kept as much as possible to prevent system monitoring errors caused by inductance differences.
The present utility model is not limited to the above embodiments, and any person who can learn the structural changes made under the teaching of the present utility model can fall within the scope of the present utility model if the present utility model has the same or similar technical solutions.
The technology, shape, and construction parts of the present utility model, which are not described in detail, are known in the art.
Claims (4)
1. The frequency converter power unit short circuit monitoring loop is characterized by comprising a frequency converter power unit circuit and an inductor, wherein the inductor comprises an inductor L 1 And inductance L 2 Inductance L 1 And inductance L 2 Connected to the power unit circuit of the frequency converter, the inductor L 1 Parallel voltage monitoring module I, inductor L 2 And a second parallel voltage monitoring module.
2. The short-circuit monitoring circuit for a power unit of a frequency converter according to claim 1, wherein the power unit circuit of the frequency converter is provided with a positive direct current bus and a negative direct current bus, and an inductance L is connected in series with the positive direct current bus 1 Series inductance L on negative DC bus 2 。
3. The circuit of claim 1, wherein the voltage monitoring module monitors the inductance L 1 Voltage value U of (2) 1 Second monitoring inductance L of voltage monitoring module 2 Voltage value U of (2) 2 Voltage value U 1 And a voltage value U 2 And feeding back to the control system to judge whether the frequency converter power unit circuit has short circuit fault.
4. The inverter power cell short circuit monitoring circuit of claim 1 wherein the inverter power cell circuit is further provided with three phase electrical interfaces phase U, phase V and phase W.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320802149.6U CN219842536U (en) | 2023-04-12 | 2023-04-12 | Frequency converter power unit short circuit monitoring loop |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320802149.6U CN219842536U (en) | 2023-04-12 | 2023-04-12 | Frequency converter power unit short circuit monitoring loop |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN219842536U true CN219842536U (en) | 2023-10-17 |
Family
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202320802149.6U Active CN219842536U (en) | 2023-04-12 | 2023-04-12 | Frequency converter power unit short circuit monitoring loop |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN219842536U (en) |
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2023
- 2023-04-12 CN CN202320802149.6U patent/CN219842536U/en active Active
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