JPS6355290B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for detecting anti-phase and open phase of a three-phase AC power source.

Generally, the rotation direction of a three-phase motor or the like connected to a three-phase AC power source is determined by the phase order of the power source. Therefore, in order to set each phase of the three-phase AC power supply in a predetermined phase order, a device is required that detects the phase order and detects the case of reverse phase or open phase.

Conventionally, as this type of phase sequence detection device, for example, as shown in FIG. 1, three-phase AC power lines R, S,
A circuit system has been proposed in which a wiring circuit consisting of a resistor r, a capacitor C, and an excitation coil L is connected to T. That is, in the circuit shown in FIG.
Utilizing the fact that the voltage between the excitation coil L terminals changes during positive phase and anti-phase due to the relationship between load impedance and power supply vector, the relay is energized within this voltage change range, and the phase sequence installed in the power supply line is activated. The modified relay contact is configured to operate. Therefore, the relationship between positive phase and anti-phase in the conventional circuit configured as described above is shown in vector diagrams as shown in FIGS. 2 and 3.

Figures 2a and b show the direction and vector diagram of the current flowing through the circuit during positive phase. In this case, the vector of the current i _L flowing through the exciting coil L is the combination of the T-phase current i _T and the S-phase current i _S. From the relationship, it can be found by the following formula.

i _L = 2cos7.5゜ ...(1) On the other hand, Figure 3 a and b show the direction and vector diagram of the current flowing in the circuit when the phase is reversed. In this case, the vector of the current i _L flowing through the exciting coil L is , is obtained from the relationship between the R-phase current i _R and the S-phase current i _S using the following equation.

i _L = 2cos52.5゜ ...(2) Therefore, from the relationship of equations (1) and (2) above, the rate of change of the current signal flowing through the exciting coil L during positive phase and anti-phase is expressed by the following equation: It becomes like this.

Positive phase/antiphase = 2cos7.5゜/2cos52.5゜=1.629...
(3) As is clear from the above equation (3), according to the conventional circuit system, the rate of change of current during positive phase and anti-phase is small, so the voltage induced between both terminals of exciting coil L The change is also small, and as a result, in order to energize the relay with the voltage change that occurs in the excitation coil L when the phase is out of phase, there is a problem that it is extremely difficult to detect the out-of-phase state when considering fluctuations in the power supply voltage. .

Furthermore, according to the conventional circuit system shown in FIG.
When the T phase to which the excitation coil L is connected becomes an open phase, the open phase can be detected because no voltage is applied to the terminals of the excitation coil L. However, R
When the phase and S phase are open, the exciting coil L
Approximately 1/2 of the line voltage (in the case of equal impedance) is generated as a residual voltage between the terminals of the relay, making relay operation unstable and making it impossible to detect an open phase condition.

Therefore, the inventor of the present invention conducted various studies and made prototypes in order to completely overcome the problems of the circuit system for detecting anti-phase open phase of the conventional three-phase AC power supply mentioned above. By connecting the collector terminal, base terminal, and emitter terminal of the transistor through appropriate resistors and capacitors, the collector output is significantly reduced during anti-phase compared to when the phase is positive, and the collector output is also By the output becoming zero,
It was found that anti-phase and open-phase states can be properly detected.

Therefore, an object of the present invention is to be able to reliably detect out-of-phase and open-phase states with a simple circuit configuration, to simplify the detection circuit, and to reduce power consumption and improve reliability. The purpose of the present invention is to provide an antiphase/open phase detector that can be used.

In order to achieve the above object, in the present invention, a three-phase AC power supply line is connected to one of the collector terminal, base terminal, and emitter terminal of each transistor through a reactance element. It is connected to a terminal and configured to detect anti-phase and open-phase states based on the emitter output of the transistor.

In the anti-phase/out-of-phase detector described above, it is preferable to connect a resistor to the collector side of the transistor, connect a capacitor to the base side, and further connect a detection resistor to the emitter side.

Alternatively, a capacitor or coil may be connected to the collector side of the transistor, a resistor or coil may be connected to the base side, and a detection resistor may be further connected to the emitter side.

Further, as the anti-phase open phase detector, it is preferable to connect a constant voltage diode between the collector and emitter of the transistor, and to connect a protective diode between the base and emitter of the transistor.

Next, embodiments of the anti-phase open phase detector according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 4 is a circuit diagram showing an embodiment of the anti-phase open phase detector according to the present invention, in which the three-phase AC power line R,
S and T are coupled by an npn type transistor Tr. That is, the power line R phase is connected to the collector terminal of the transistor Tr via the resistor _r1 ,
The S phase is connected to the base terminal of the transistor _Tr via a capacitor C, and the T phase is connected to the emitter terminal of the transistor Tr via a detection resistor _r2 .

In this case, the detection resistor _r2 and the capacitor C are set so as to satisfy the following condition.

r ₂ (1+h _FE )≪1ω/C...(4) However, h _FE : Emitter ground current amplification factor By configuring the circuit in this way, in the circuit shown in Figure 4, the three-phase AC power lines R, S ，
When T is in positive phase, the voltage relationship becomes like a vector diagram as shown in FIG. 5a. In addition, Figure 5a
, V _RS , V _ST , and V _TR are the line voltages of the three-phase AC power supply line, V _CE is the voltage between the collector and emitter of the transistor Tr, and V _BE is the voltage between the collector and emitter of the transistor Tr.
The voltage between the base and emitter of the Tr and i _B indicate the base current of the transistor Tr, respectively.

Therefore, when considering the line voltage V _TR (V _CE ) as a reference, the line voltage V _ST (V _BE ) will be delayed by 60°. However, the base current i _B of the transistor Tr is
The phase is 90 degrees ahead of the line voltage V _ST , and as a result, the base current i _B is 30 degrees ahead of the collector-emitter voltage V _CE of the transistor Tr.

From the above facts, it can be seen that the _fifth
As shown in Figure b, a pulse voltage of 150° is generated within one cycle of the base current _iB .

On the other hand, as shown in Fig. 6, when the anti-phase open phase detector is in the anti-phase state, the voltage relationship is as shown in Fig. 7 a.
It looks like the vector diagram shown in . In this case, considering the line voltage V _RS (V _CE ) as a reference, the base current
i _B is 150° behind the collector-emitter voltage V _CE of the transistor Tr. As a result, a 30° pulse voltage is generated within one cycle of the base current _iB between the terminals of the detection resistor _r2 connected to the emitter terminal of the transistor Tr, as shown in Figure 7b. Become.

As is clear from the above, according to the detector of the present invention, when the output voltage at the detection resistor _r2 is averaged, the output voltage generation rate is
150°/360°, and 30°/360° in antiphase, and the rate of change of these signals (in positive phase/inverse phase) is 5
It will be doubled. Therefore, the signal change rate between positive phase and anti-phase times obtained by the detector of the present invention can be improved by about three times as compared to the conventional circuit system.

Furthermore, according to the detector of the present invention shown in FIG.
Phase loss in phase alternating current power lines R, S, and T can be detected as follows.

When the R phase is open, the collector current of the transistor Tr does not flow.

When the S phase is open, the base current of the transistor Tr does not flow.

When the T phase is open, the emitter current of the transistor Tr does not flow.

Therefore, when any of the three-phase AC power lines R, S, and T is in an open phase state, the transistor
Since the Tr does not operate and no voltage is generated across the detection resistor _r2 , an open phase state can be reliably detected.

FIG. 8 shows an example of a circuit in which the anti-phase open phase detector according to the present invention can be put into practical use. That is, in the circuit shown in FIG. 8, to protect the transistor Tr, a constant voltage diode ZD including a detection resistor _r2 is connected in parallel between the collector and the emitter, and a diode D is connected between the base and the emitter. Additionally, resistors r ₃ and r ₄ are additionally connected.
With this configuration, anti-phase and open-phase states of the three-phase AC power lines R, S, and T can be detected by the detection circuit DC connected between the terminals of the detection resistor _r2 . Furthermore, by changing the circuit elements on the collector side and base side of the transistor Tr to the circuit shown in FIG. 8, and modifying the circuit as shown in FIGS. 9 to 11,
Exactly the same effects as in the above embodiment can be expected.

As is clear from the various embodiments described above, the anti-phase open phase detector according to the present invention can not only achieve anti-phase detection but also properly detect the open phase of each phase compared to the conventional circuit system. can be detected. Also,
Since the detector according to the present invention operates without contact,
Since the detection circuit can have a configuration in which the detection output is directly input to the semiconductor circuit, it has many advantages such as the circuit configuration can be made smaller and simpler, and power consumption can be reduced.

Therefore, the detector of the present invention can be widely applied as a phase sequence detector to three-phase AC power supply circuits such as general induction machines and compressor motors in which the direction of rotation is determined.

Although the preferred embodiments of the present invention have been described above, it goes without saying that various design changes can be made without departing from the spirit of the present invention.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a conventional phase sequence detector, FIGS. 2a and 2b are circuit diagrams and vector diagrams of the phase sequence detector shown in FIG.
b shows a circuit diagram and a vector diagram of the phase sequence detector shown in FIG. 1 at the time of anti-phase, and FIG. 4 is a circuit diagram showing an embodiment of the anti-phase open phase detector according to the present invention,
FIGS. 5a and 5b show a vector diagram and an output characteristic waveform diagram of the detector shown in FIG. 4 at the time of positive phase, respectively,
6 is a circuit diagram of the detector shown in FIG. 4 when the phase is out of phase, FIGS. 7a and 7b are vector diagrams and output characteristic waveform diagrams of the circuit shown in FIG. 6, and FIG. 9 to 11 are circuit diagrams showing modifications of the circuit shown in FIG. 8, respectively. R, S, T...3-phase AC power line, r, _r1 ...resistor, C...capacitor, L...excitation coil, _r2 ...detection resistor, Tr...transistor, ZD...constant voltage diode, D...diode.

Claims (1)

[Claims] 1. A three-phase AC power line is connected to each of the collector terminal, base terminal, and emitter terminal of the transistor through a reactance element to either the collector terminal or the base terminal, respectively, An anti-phase open phase detector configured to detect anti-phase and open phase states using the emitter output of a transistor. 2. In the anti-phase loss detector according to claim 1, the anti-phase loss detector is formed by connecting a resistor to the collector side of the transistor, connecting a capacitor to the base side, and further connecting a detection resistor to the emitter side. Phase detector. 3. In the anti-phase open phase detector according to claim 1, a capacitor or coil is connected to the collector side of the transistor, a resistor or coil is connected to the base side, and a detection resistor is further connected to the emitter side. Anti-phase open phase detector. 4. In the anti-phase open phase detector according to any one of claims 1 to 3, a constant voltage diode is connected between the collector and emitter of the transistor, and a protective diode is connected between the base and emitter of the transistor. Anti-phase open phase detector.