CN105655982A - Frequency converter output current detection circuit and detection method thereof - Google Patents
Frequency converter output current detection circuit and detection method thereof Download PDFInfo
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- CN105655982A CN105655982A CN201610186861.2A CN201610186861A CN105655982A CN 105655982 A CN105655982 A CN 105655982A CN 201610186861 A CN201610186861 A CN 201610186861A CN 105655982 A CN105655982 A CN 105655982A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
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- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measuring Instrument Details And Bridges, And Automatic Balancing Devices (AREA)
- Emergency Protection Circuit Devices (AREA)
- Inverter Devices (AREA)
Abstract
The invention discloses a frequency converter output current detection circuit and a detection method thereof. The circuit comprises a first Hall sensor, a second Hall sensor, an anti-phase operational amplifier, an additive operation device and an anti-phase operation device, two-phase power lines penetrate through the first Hall sensor and the second Hall sensor respectively, and only one phase power line in the two-phase power line penetrating through the first Hall sensor is the same as one phase in the two-phase power line penetrating through the second Hall sensor; the first Hall sensor outputs a first detection signal, the second Hall sensor outputs a second detection signal, the first detection signal and the second detection signal are subjected to operation conducted by the anti-phase operational amplifier, then a first phase current signal and a second phase current signal are obtained, and the first phase current signal and the second phase current signal are input into the additive operation device and then processed through the anti-phase operation device, so that a third phase current signal is obtained. By means of the frequency converter output current detection circuit and the detection method thereof, inter-phase and oppositely output short-circuit protection can be achieved, and the frequency converter output current detection circuit and the detection method thereof have the advantages of being simple in structure and low in cost.
Description
Technical field
The present invention relates to current detecting research field, particularly to a kind of output current of frequency converter testing circuit and detection method thereof.
Background technology
At present, the detection of output current of frequency converter is generally adopted method below: adopting three Hall elements or diverter (A, B, C) respectively the three-phase of converter to be exported electric current U, V, W and detect, structure is referring to Fig. 1. Each power line is respectively provided with a Hall element or diverter. Adopt in this way, it is possible to detect the size of three-phase output electric current, carry out the short-circuit protection of U, V, W three-phase short-circuit protection between phase and phase and three-phase (PE) ground-to-ground.
In actual applications, three-phase exporting the size of electric current when detecting, add up to the principle of zero according to three-phase current, it is only necessary to detect any of which biphase current, another phase can be obtained by calculating. It addition, the short-circuit protection that U, V, W three-phase is between phase and phase whether specifically refer to detection U and V or U and W or V and W short-circuit, this phase fault has only to detect arbitrarily biphase equally. But; carry out the short-circuit protection of U, V, W three-phase difference (PE) over the ground; need above three-phase, all have Hall current detection to realize; referring to Fig. 2; if only arranging Hall element (A, B) on the power line that U, V are biphase to carry out current detecting; so will be unable to protection during W relative ground circuit, be easily caused converter and damage. Based on this consideration, although size and the phase fault protection of three-phase output electric current can realize with 2 sensors, but but can not accomplish the three-phase output protection to PE short circuit. Therefore general existing converter still adopts three sensors, namely each with a sensor above U, V, W three-phase.
Summary of the invention
Present invention is primarily targeted at the shortcoming overcoming prior art with not enough; a kind of output current of frequency converter testing circuit is provided, only with two Hall elements in this testing circuit, the detection of three-phase current can be realized; alternate and relatively short-circuit protection can be realized again, provide cost savings.
Another object of the present invention is to provide a kind of detection method based on above-mentioned output current of frequency converter testing circuit; the numerical value that the method gathers according to two Hall elements; three-phase current and each electric current relatively can be obtained, thus realizing protection through calculating.
The purpose of the present invention is realized by following technical scheme: output current of frequency converter testing circuit, including the first Hall element, the second Hall element, rp-op amp, adder calculator, anti-phase arithmetical unit, described first Hall element, the second Hall element have two-phase power supply line traverse respectively, and it is mutually identical with in the two-phase power supply line in the second Hall element to only have a phase power line in the two-phase power supply line of the first Hall element; First Hall element output the first detection signal, second Hall element output the second detection signal, first-phase current signal and second-phase current signal is obtained after first detection signal and the second detection signal inverted operational amplifier computing respectively, described first-phase current signal and second-phase current signal are input to adder calculator then through an anti-phase arithmetical unit, obtain third phase current signal. The present invention passes through such scheme, only with two Hall elements, namely achieves the detection of three-phase current, realizes again alternate and relatively short-circuit protection, have the advantage that cost is low.
Preferably, be equipped with the first voltage lifting circuit between described first Hall element and rp-op amp, between the second Hall element and rp-op amp, described first voltage lifting circuit for detect first in signal and the second detection signal original with the 0V sinusoidal wave lifting being benchmark be with the 2.5V sine wave being benchmark.
Preferably; described output current of frequency converter testing circuit also includes comparison circuit; described first-phase current signal, second-phase current signal, third phase current signal are separately input to comparison circuit; comparison circuit is for comparing first-phase current signal, second-phase current signal, third phase current signal with default overcurrent protection threshold value respectively; once there is stream; then send control signals to the CPU of converter, and then triggering converter short-circuit protection circuit carries out short-circuit protection.
Further, be provided with the second voltage lifting circuit before described comparison circuit, described second voltage lifting circuit in first-phase current signal, second-phase current signal, third phase current signal original with the 0V sinusoidal wave lifting being benchmark be with the 2.5V sine wave being benchmark.
A kind of detection method based on above-mentioned output current of frequency converter testing circuit, the signal negative value equal to first-phase current signal is detected according to first, second detection signal is equal to the negative value of second-phase current signal, first-phase current signal, second-phase current signal, third phase current signal are added and are zero, obtain third phase current signal; Preset an overcurrent protection threshold value; by first-phase current signal, second-phase current signal, third phase current signal three value compare with this overcurrent protection threshold value respectively; once more than this overcurrent protection threshold value, then send control signal and realize the short-circuit protection of converter.
The present invention compared with prior art, has the advantage that and beneficial effect:
The detection of existing inverter current and overcurrent protection (especially U, V, W tri-relative ground circuit protection) are with three Hall elements realizations; and the present invention only needs to adopt two Hall elements to realize; each Hall element is each passed through two output leads; and wherein a phase output will also cross two Hall elements; measured value according to Hall element can obtain U, V, W three-phase output electric current by corresponding relation and carry out three relative ground circuit protections; provide cost savings, make system more simplify.
Accompanying drawing explanation
Fig. 1 is the one of which annexation schematic diagram of Hall element and power line in the detection of existing inverter current.
Fig. 2 is the wherein another kind of annexation schematic diagram of Hall element and power line in the detection of existing inverter current.
Fig. 3 is the annexation schematic diagram of Hall element and power line in the embodiment of the present invention 1 current detecting.
Fig. 4 is the circuit diagram of the embodiment of the present invention 1 current detection circuit.
Fig. 5 utilizes adder calculator to obtain the circuit diagram of third phase electric current in the embodiment of the present invention 1.
Fig. 6 is the annexation schematic diagram of Hall element and power line in the embodiment of the present invention 2 current detecting.
Fig. 7 is the annexation schematic diagram of Hall element and power line in the embodiment of the present invention 3 current detecting.
Detailed description of the invention
Below in conjunction with embodiment and accompanying drawing, the present invention is described in further detail, but embodiments of the present invention are not limited to this.
Embodiment 1
As shown in Figure 3; the present embodiment output current of frequency converter testing circuit includes the first Hall element A, the second Hall element B; first Hall element A passes the U phase in U, V, W three-phase power line and V phase; second Hall element B passes the W phase in U, V, W three-phase power line and V phase; current detecting and two functions of short-circuit protection can be realized by this circuit, below in conjunction with circuit diagram, it is specifically described.
One, current detecting
Referring to Fig. 4 and Fig. 5, for the first Hall element A, first Hall element A output the first detection signal, this detection signal first passes through the first voltage lifting circuit of the compositions such as R569, R570, and the first voltage lifting circuit was originally put the first detection signal centered by 0V and was lifted to the sinusoidal wave lifting of the voltage waveform benchmark of point centered by 2.5V is with the 2.5V sine wave being benchmark. Then sending signal to rp-op amp IC505, obtain first-phase current signal after inverted operational amplifier computing, this signal is W phase current signal.
In like manner, the second Hall element B first passes through the first voltage lifting circuit of the compositions such as R603, R604, obtains second-phase current signal after being then passed through the computing of rp-op amp MC34074, and this signal is U phase current signal.
After obtaining W phase current signal and U phase current signal, adopt the circuit shown in Fig. 5, two paths of signals is input to after adder calculator then through an anti-phase arithmetical unit, obtains third phase current signal, i.e. V phase current signal.
So far, the present embodiment, only with two Hall elements, namely achieves the detection of three-phase current, it is possible to the controller that the current signal obtained is sent to outside operates for the storage of current signal, detection etc.
Two, short-circuit protection
After obtaining three-phase current through foregoing circuit, it is also possible to carry out the short-circuit protection of U, V, W three-phase short-circuit protection and three between phase and phase relatively (PE) further. Short-circuit protection is realized by comparison circuit.
Referring to Fig. 4, for the first Hall element A, after detection obtains W phase current, first pass through the second voltage lifting circuit and (include R535, R544, R536 etc.), second voltage lifting circuit in W phase current signal original with the 0V sinusoidal wave lifting being benchmark be with the 2.5V sine wave being benchmark, it is then input to comparison circuit (IC501 see in figure), W phase current signal is compared by comparison circuit with the overcurrent protection threshold value preset, if it exceeds overcurrent protection threshold value, then send control signals to the CPU of converter, and then triggering converter short-circuit protection circuit carries out short-circuit protection.
In like manner, after second Hall element B detection obtains U phase current, first pass through the second voltage lifting circuit and (include R609, R610, R611 etc.), second voltage lifting circuit is being lifted to the voltage waveform of point centered by 2.5V by original putting centered by 0V in U phase current signal, it is then input to comparison circuit (IC502 see in figure), U phase current signal is compared by comparison circuit with the overcurrent protection threshold value preset, if it exceeds overcurrent protection threshold value, then send control signals to the CPU of converter, and then triggering converter short-circuit protection circuit carries out short-circuit protection.
By the present embodiment, phase fault and relatively (PE) short circuit all can detect, it is achieved that only carry out short-circuit protection with two Hall elements, have simple in construction, an advantage that cost is low.
Embodiment 2
The present embodiment except following characteristics other structures with embodiment 1:
In embodiment 1; first Hall element A passes the U phase in U, V, W three-phase power line and V phase; second Hall element B passes the W phase in U, V, W three-phase power line and V phase; in the present embodiment; referring to Fig. 6; first Hall element A traverse U phase and W phase; output the first detection signal is-V; second Hall element B traverse W phase and V phase; output the second detection signal-U; by adopting Fig. 4, circuit shown in 5, it is possible to obtain U, V, W three-phase current signal, and then short-circuit protection can be realized according to three-phase current signal.
Embodiment 3
The present embodiment except following characteristics other structures with embodiment 1:
In the present embodiment; referring to Fig. 7; first Hall element A traverse U phase and W phase; output the first detection signal is-V; second Hall element B is through U phase and V phase, and output the second detection signal-W, by adopting Fig. 4, circuit shown in 5; U, V, W three-phase current signal can be obtained, and then short-circuit protection can be realized according to three-phase current signal.
Above-described embodiment is the present invention preferably embodiment; but embodiments of the present invention are also not restricted to the described embodiments; the change made under other any spirit without departing from the present invention and principle, modification, replacement, combination, simplification; all should be the substitute mode of equivalence, be included within protection scope of the present invention.
Claims (5)
1. output current of frequency converter testing circuit, it is characterized in that, including the first Hall element, the second Hall element, rp-op amp, adder calculator, anti-phase arithmetical unit, described first Hall element, the second Hall element have two-phase power supply line traverse respectively, and it is mutually identical with in the two-phase power supply line in the second Hall element to only have a phase power line in the two-phase power supply line of the first Hall element; First Hall element output the first detection signal, second Hall element output the second detection signal, first-phase current signal and second-phase current signal is obtained after first detection signal and the second detection signal inverted operational amplifier computing respectively, described first-phase current signal and second-phase current signal are input to adder calculator then through an anti-phase arithmetical unit, obtain third phase current signal.
2. output current of frequency converter testing circuit according to claim 1, it is characterized in that, be equipped with the first voltage lifting circuit between described first Hall element and rp-op amp, between the second Hall element and rp-op amp, described first voltage lifting circuit for detect first in signal and the second detection signal original with the 0V sinusoidal wave lifting being benchmark be with the 2.5V sine wave being benchmark.
3. output current of frequency converter testing circuit according to claim 1 and 2; it is characterized in that; described output current of frequency converter testing circuit also includes comparison circuit; described first-phase current signal, second-phase current signal, third phase current signal are separately input to comparison circuit; comparison circuit is for comparing first-phase current signal, second-phase current signal, third phase current signal with default overcurrent protection threshold value respectively; once there is stream; then send control signals to the CPU of converter, and then triggering converter short-circuit protection circuit carries out short-circuit protection.
4. output current of frequency converter testing circuit according to claim 1, it is characterized in that, be provided with the second voltage lifting circuit before described comparison circuit, described second voltage lifting circuit in first-phase current signal, second-phase current signal, third phase current signal original with the 0V sinusoidal wave lifting being benchmark be with the 2.5V sine wave being benchmark.
5. the detection method based on the output current of frequency converter testing circuit described in any one of claim 1-4, it is characterized in that, the signal negative value equal to first-phase current signal is detected according to first, second detection signal is equal to the negative value of second-phase current signal, first-phase current signal, second-phase current signal, third phase current signal are added and are zero, obtain third phase current signal; Preset an overcurrent protection threshold value; by first-phase current signal, second-phase current signal, third phase current signal three value compare with this overcurrent protection threshold value respectively; once more than this overcurrent protection threshold value, then send control signal and realize the short-circuit protection of converter.
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| CN201610186861.2A CN105655982B (en) | 2016-03-28 | 2016-03-28 | Output current of frequency converter detection circuit and its detection method |
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| CN201610186861.2A CN105655982B (en) | 2016-03-28 | 2016-03-28 | Output current of frequency converter detection circuit and its detection method |
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| CN105655982B CN105655982B (en) | 2018-10-30 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111812385A (en) * | 2020-07-22 | 2020-10-23 | 南京工业职业技术学院 | Three-phase bus current detection method |
| CN112415418A (en) * | 2020-10-23 | 2021-02-26 | 湖南中科电气股份有限公司 | Electromagnetic stirring variable frequency power supply fault detection circuit |
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| CN112415418B (en) * | 2020-10-23 | 2022-05-24 | 湖南中科电气股份有限公司 | Electromagnetic stirring variable frequency power supply fault detection circuit |
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| CN105655982B (en) | 2018-10-30 |
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