JP2001223062A - Zero-cross six-phase snow melting device and driving method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a snow melting device without generation of noise. SOLUTION: Bidirectional conductive circuits 11-13 are formed by connecting thyristors 21-26 by back-to-back connection, and connected to heating resistors 31-33. Three serially connected circuits are connected by Δ-connection and three-phase alternating current voltage is impressed to the top point. The operation of one of bidirectional conductive circuits 11-13 does not affect the operation of the rest of bidirectional conductive circuits 11-13. Accordingly, by getting to start conduction consecutively from the circuit, out of the bidirectional conductive circuits 11-13, of which the voltage between both ends is nearly zero, the snow melting device 1 can be started without generation of noise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a snow melting device or a heating device, and to a device provided with a large number of electronic devices such as an aircraft or a hospital operating room without disturbing radio waves or noise. The present invention relates to a snow melting device or a heating device suitable for melting snow on a road surface of an airport or heating an operating room of a hospital.

[0002]

2. Description of the Related Art Conventionally, a heater is buried under a road surface in a snow-covered area, and a snow melting apparatus is constituted by the heater and a power supply arranged indoors. When snowfall occurs in winter, the heater is energized to melt snow on the road surface and allow for an accident such as a slip accident.

[0003] Reference numeral 201 in FIG. 11 is one of the conventional snow melting devices, and has a heater 203 and a power supply device 205. In the heater 203, three resistance heating elements 23 are provided.
1 to 233 are arranged, and each resistance heating element 231 to 2
Reference numeral 33 denotes a Δ connection. Three relay elements 211 to 213 are arranged in the power supply device 205, and the R, S, and T phases of the three-phase AC voltage are applied to the heater 203 via the relay elements 211 to 213. It is configured to be.

In this snow melting apparatus 201, relays 211 to 211
Since the state of energization to the heater 203 is controlled by opening and closing the 213, the emission of the disturbing electromagnetic wave due to the surge current is extremely large.

[0005] Reference numeral 101 in FIG.
Of the heater 103 and the power supply 1
05.

In the power supply device 105, three bidirectional conducting circuits 111 to 113 are provided. Each of the bidirectional conduction circuits 111 to 113 includes thyristor elements 121 to 126 connected in anti-parallel, respectively.
A three-phase AC voltage composed of a three-phase and a T-phase is applied to the heater 103.

Reference numerals 131 to 133 in the heater 103 are as follows:
The figure shows resistance heating elements, and each of the resistance heating elements 131-133.
Are connected to each other, and the respective bidirectional conducting circuits 111 to 113
When the thyristor elements 121 to 126 are turned on in a predetermined order, the resistance heating elements 131 to 133 are energized.

[0008] The timing chart of FIG. 10 shows the timing for turning the thyristor element 121-126, the current i _a through i _c flowing to the resistance heating element 131-133.

First, at time t ₁ when the voltage between the ST phases of the three-phase AC power supply switches from a negative voltage to a positive voltage, a control signal is applied to the gates of the two thyristor elements 123 and 126 to make them conductive. At this time, a positive voltage, T
A negative voltage is applied between the -R phases, and each of the resistance heating elements 131-1 is activated by the conduction of the thyristor elements 123 and 126.
Current starts to flow through 33.

In this state, the voltage between the T and R phases is changed from negative to positive.
Time t_TwoAnd two thyristor elements 122 and 125
And then when the voltage between the RS phases becomes zero
Time t _ThreeTo replace the remaining two thyristor elements 121 and 124 with
When the conduction is performed, the operation shifts to the steady operation, and the resistance heating elements 131
To 133, an alternating current flows.

When a steady operation is performed and the temperature of the heater 103 rises to a predetermined temperature or higher, the control signals to the gates of the thyristor elements 121 to 126 are stopped, and the thyristor elements 121 to 126 are naturally extinguished.

Here, the voltage application to the gate terminal is stopped at time t ₄ when the voltage between the R and S phases becomes zero,
The arc is extinguished in order from the thyristor element where the forward current stops flowing.

However, the thyristor element 1 as described above
In the control methods 21 to 126, the thyristor elements 121 to
A transient voltage fluctuation occurs when turning on or extinguishing 126, and a switching transient surge current of 20 kHz to 30 kHz flows. This surge current is the resistance heating element 1
If it flows through 31-133 or a lead wire, an interfering electromagnetic wave will be radiated. In the timing chart of FIG. 10, when the two thyristor elements 122 and 125 conduct at time t ₂ , the voltage applied to the resistance heating elements 131 and 133 changes suddenly, which causes noise.

In recent years, there has been a demand for burying the above-described snow melting system in an underground such as an apron, a waiting road, and a taxiway at an airport, instead of a runway for takeoff and landing of an airplane. This is because, when there is heavy snowfall at the airport, the runway where airplanes take off and land can be relatively easily removed by arranging several snowplows in diagonal rows, while aprons and waiting paths In places such as taxiways, if the number of waiting airplanes is large, it is difficult to use the mobility of the snowplow as described above because it is difficult to stand by while waiting for snow removal. is there.

If a snow melting device that emits jamming waves as in the prior art is provided in such a place where the vehicle stays for a relatively long time, the electronic equipment mounted on the aircraft is damaged, and the flight is stopped. This can be a hindrance.

There is also a demand that the radio wave reflecting surface of the glide slope, which is one of the aviation security facilities, be melted by a conventional heating device. The radio wave reflecting surface of this glide slope is intended to always emit a wide guided radio wave as a guide to the airplane that lands, and is to be emitted after being reflected by the radio wave reflecting surface. In order to remove the snow cover above, if a snow melting device that emits a conventional jamming radio wave is buried, the jamming radio wave from the snow melting device mixes into the guided radio wave for the landing guide, Damage to the electronics of the arriving airplane can be a major hindrance to landing.

In recent hospitals, advanced surgical equipment equipped with electronic equipment is provided. However, such air-conditioning of the operating room uses a method in which warm air circulates between the operating room and the ward. For this reason, it has been unavoidable that a subject suffers from infection due to being exposed to warm air from a ward during surgery.

It is sufficient to install an air conditioner dedicated to the operating room. However, this requires a large amount of cost. In addition, in the case of heating by air conditioning, it is impossible to avoid weak noise and airflow. In the case of an operation that requires a long time, a complaint such as annoyance is given by a doctor or a nurse, and it has been desired to avoid the complaint. However, using a conventional heat generating device that emits jamming waves of a contact switch type would damage surgical instruments.

[0019]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned disadvantages of the prior art, and an object of the present invention is to provide a method for operating a snow melting apparatus for preventing a disturbing electromagnetic wave from being emitted from the snow melting apparatus. To provide. Also,
Another object of the present invention is to provide a heating device that does not emit jamming radio waves.

[0020]

In order to solve the above problems, the invention according to claim 1 comprises a bidirectional conduction circuit in which thyristor elements are connected in anti-parallel, and a resistance heating element capable of generating heat by energization. A heating circuit is configured by connecting in series to form a heating circuit, and a plurality of heating elements configured to apply a three-phase AC voltage by connecting the three heating circuits with each other by Δ are connected under a road surface by a snow melting apparatus. is there.

According to a second aspect of the present invention, in the snow melting apparatus according to the first aspect, the heating circuit is configured such that at least one resistance heating element is connected in series to one bidirectional conduction circuit. It is a configured snow melting device.

According to a third aspect of the present invention, there is provided the snow melting apparatus according to the first aspect, wherein the plurality of heat generating circuits according to the second aspect are connected in parallel.

According to a fourth aspect of the present invention, in the snow melting apparatus according to the first aspect, the heating circuit includes a plurality of the resistance heating elements connected in parallel to one bidirectional conduction circuit.
It is a snow melting device configured to be connected in series.

According to a fifth aspect of the present invention, there is provided an operating method for controlling the snow melting apparatus according to any one of the first to fourth aspects, wherein the respective thyristor elements are cut off from each other. This is an operation method in which, among the directional conduction circuits, bidirectional conduction circuits whose applied voltage has become substantially zero volts can be sequentially turned on.

According to a sixth aspect of the present invention, there is provided the operation method according to the fifth aspect, wherein the bidirectional conduction circuit is sequentially cut off.

According to a seventh aspect of the present invention, there is provided an antenna for transmitting an induced radio wave, and a radio wave reflecting surface formed of a part of a road surface in an airport and reflecting the induced radio wave. 4. The snow melting device according to claim 1, wherein the snow melting device is an aircraft guidance device buried under a road surface of the radio wave reflecting surface.

According to an eighth aspect of the present invention, the heat generating circuit is constituted by connecting a bidirectional conductive circuit in which thyristor elements are connected in reverse parallel to each other and a resistance heating element capable of generating heat by energization in series. A heating device configured to embed a plurality of heating elements configured to apply a three-phase AC voltage by Δ-connecting them under a road surface.

According to a ninth aspect of the present invention, in the heating apparatus according to the eighth aspect, the heating circuit is configured such that at least one resistance heating element is connected in series to one bidirectional conduction circuit. It is a configured heating device.

A tenth aspect of the present invention is the heating apparatus according to the eighth aspect, wherein the plurality of the heat generating circuits according to the ninth aspect are connected in parallel.

According to an eleventh aspect of the present invention, in the heating apparatus according to the eighth aspect, the heating circuit includes the bidirectional conduction circuit 1.
A heating device configured to connect a plurality of resistance heating elements connected in parallel to each other in series.

The present invention is configured as described above, and has a bidirectional conduction circuit in which thyristor elements are connected in antiparallel. Therefore, when a control signal is applied to the gate of the thyristor element, the bidirectional conduction circuit becomes conductive in both directions.

When a two-way conductive circuit is connected in series to a resistance heating element buried under a road surface of an airport or on a radio wave reflecting surface and the like, and three of the series-connected circuits are Δ-connected, a three-phase AC power supply is provided. Thus, the resistance heating element can generate heat.

In this case, since the resistance heating element and the bidirectional conduction circuit are connected by Δ, even if one bidirectional conduction circuit changes from cutoff to conduction or from conduction to cutoff, the other bidirectional connection circuit changes. The voltage applied to the directional conduction circuit does not change,
Therefore, no interfering electromagnetic waves (noise) are generated at the time of starting or shutting off.

At the time of start-up, the bidirectional conduction circuit is first cut off, and then a control signal is applied to the gate of the bidirectional conduction circuit of which the voltage at both ends is substantially zero volts, and sequentially. When the conductive state is established, the current gradually starts to flow.

[0035]

Embodiments of the present invention will be described with reference to the drawings. Referring to FIG. 1, reference numeral 1 denotes a snow melting apparatus using the control method of the present invention.

The snow melting apparatus 1 comprises three resistance heating elements 31
33 and three bidirectional conductive circuits 11 to 13, and each of the resistance heating elements 31 to 33 is
1 to 13 are connected in series, and the heat-generating circuits connected in series are configured by Δ connection.

Each connection portion of the Δ-connected circuit is configured so that three-phase AC, R-phase, S-phase, and T-phase voltages are respectively applied.

Each of the bidirectional conducting circuits 21 to 23 is configured by connecting two thyristor elements in antiparallel. Reference numerals 21 to 26 indicate the thyristor elements. The thyristor elements 21 to 26 used here are reverse blocking three-terminal thyristor elements. In a non-conducting state, no current flows from the anode terminal to the cathode terminal or from the cathode terminal to the anode terminal. When a voltage is applied, the current flows only in the direction from the anode terminal to the cathode terminal. In addition, the reverse blocking three-terminal thyristor element is designed so that a reverse bias state occurs between the anode terminal and the cathode terminal (forced arc extinction) or that the arc is extinguished when the current becomes zero (natural arc extinction). It has become.

The circuit operation of the snow melting apparatus 1 will be described with reference to the timing chart of FIG. In the figure, R-S,
ST and TR indicate the inter-phase voltage, RS is the voltage of the R phase based on the S phase, ST is the voltage of the S phase based on the T phase, and T -R is the voltage of the T phase based on the R phase.

First, the timing at which any of the inter-phase voltages of RS, ST, and TR changes from negative to positive is detected, and the thyristor in the bidirectional conduction circuit connected between the phases is detected. The element is made conductive.

In the time chart of FIG. 2, at time t ₁ , the inter-phase voltage between S and T becomes zero. At this time t ₁ , the thyristor element 23 connected between the S phase and the T phase A trigger voltage is applied to the 24 gate terminals, and the gate terminal becomes conductive. In this state, only the bidirectional conduction circuit 12 constituted by the thyristor elements 23 and 24 becomes conductive.

When the voltage between the S-phase and the T-phase rises after time t ₁ , the voltage passes through the bidirectional conduction circuit 12 to the resistance heating element 32 connected between the S-phase and the T-phase. Electric current flows. The symbol i _{1 in} FIG. 3 indicates the current.

The voltage of each phase of R, S and T has a phase of 120
°, and one cycle of the voltage change of each phase is represented by a symbol T ₀ , and after any one inter-phase voltage becomes zero, T _0/6 (6 minutes of one cycle) After a lapse of one period, one of the other inter-phase voltages becomes zero.

Here, at time t ₁ , the inter-phase voltage between S and T is zero, and at time t ₂ after a lapse of T _0/6 from time t ₁ , the inter-phase voltage between T and R is obtained. Is zero.

When the inter-phase voltage between R and S becomes zero at time t ₂ , this is detected, and when a trigger voltage is applied to the gate terminals of the thyristor elements 21 and 22 connected between the R and S phases, In addition to the bidirectional conducting circuit 12 which is already conducting,
The bidirectional conduction circuit 11 constituted by the thyristor elements 21 and 22 becomes conductive.

When time t ₂ elapses and a voltage difference occurs between the R phase and the S phase, a current is supplied to the resistance heating element 31 connected between the R phase and the S phase via the bidirectional conduction circuit 11. Flows.

The symbol i _{2 in} FIG. 4 indicates the current,
Via the two bidirectional conducting circuits 11 and 12 which have conducted, 2
Currents i ₁ and i ₂ flow through the resistance heating elements 31 and 32, respectively.

[0048] Further elapses by a time T _0/6 from the time t _2, the At time t _3, the interphase voltage between T-R becomes zero. At time t _3, upon detecting a zero voltage, a voltage is applied to the gate terminal of the T-phase and R-phase thyristor element 25, 26 connected between and to the possible conduction states.

When time t ₃ elapses and a voltage difference occurs between the T phase and the R phase, a current flows through the bidirectional conduction circuit 13 composed of the thyristor elements 25 and 26. Symbol i in FIG.
₃ shows the current, after a time t _3, further T ₀
/ 6 only time up to the time t ₄ has elapsed, the current i ₁ ~ described above each of the respective bidirectional conducting circuits 11 to 13
i ₃ flows.

Next, at time t ₄ , the inter-phase voltage between SR becomes zero again. Then, when the time t ₄ elapses,
Polarity of the phase between the voltage between the S-R is reversed, bi-directional conducting circuit 12 connected between them, the voltage of the opposite direction is applied to the time t ₄ before.

The bidirectional conduction circuit 12 whose applied voltage is reversed
Of the two thyristor elements 23 and 24, the one that is forward biased switches from one thyristor element 23 to the other thyristor element 24, but the two thyristor elements 23 and 24 in the bidirectional conduction circuit 12 the 24 time t ₁ after, continues to apply the trigger voltage, therefore,
The current continues to flow through the bidirectional conduction circuit 12 only by switching the thyristor elements through which the current flows.

Reference numeral i _{4 in} FIG. 6 indicates a current flowing through the bidirectional conductive circuit 12 to the resistance heating element 32 in a direction opposite to that before time t ₄ . In this state, the directions of the currents i ₂ and i ₃ flowing through the other bidirectional conducting circuits 11 and 13 do not change.

[0053] After a time t _4, every time elapses by a time T _0/6, among the three bidirectional conducting circuits 11 to 13,
Although the polarity of the voltage applied to any one of the bidirectional conducting circuits is reversed, the trigger voltage has already been applied to the thyristor elements 21 to 26 in each of the bidirectional conducting circuits 11 to 13, and therefore, Even if the polarity of the voltage applied to each of the bidirectional conducting circuits 11 to 13 is reversed, the bidirectional conducting circuits 11 to 13 are not interrupted. Therefore, the current does not change suddenly and noise does not occur.

[0054] current i ₂ ~i ₄ of FIG. 6, T from the time t _{4 0} /
6 only the time has elapsed, a current flowing through to the time t ₅ at which the phase between the voltage between the R-S is zero to the resistance heating element 31 to 33, 7 and 8, after the lapse of time t _5, respectively T _0/6 ,
The current flowing between time t ₆ and time t ₇ after the lapse of 2 × T ₀ and its direction are shown.

After time t ₃ when each of the bidirectional conducting circuits 11 to 13 is in the conducting state, the snow melting apparatus 1 shifts to a steady operation, and when the energization to the resistance heating elements 31 to 33 is stopped,
When the application of the trigger voltage to the gate terminals of the thyristor elements 21 to 26 is stopped all at once (time t ₈ ), and the thyristor elements 21 to 26 are naturally extinguished, energization can be stopped without generating noise.

Reference numeral 50 in FIG. 12 indicates an airport facility, which has a runway 51 and an antenna 52 erected at an end of the runway 51.

The antenna 52 is configured to transmit guided radio waves for guiding an aircraft into the air, and a radio wave reflecting surface 53 made of asphalt laid on the ground is disposed in front of the antenna 52. ing. Reference numeral 55 in FIG. 12 indicates an aircraft guidance device having the antenna 52 and the radio wave reflecting surface 53.

Reference numeral 57 in the figure denotes an aircraft that is about to land on the runway 51. The guided radio wave transmitted from the antenna 52 directly arrives at the aircraft 57 and the radio wave reflecting surface 53. Some of the light reaches the aircraft 57 after being reflected by the airplane. Reference numeral 54 in FIG. 12 indicates a guided radio wave that reaches the aircraft 57 directly and reflected, and the aircraft 57 determines a course according to the two types of guided radio waves and lands on the runway 51.

The aircraft guidance apparatus 55 of the present invention is arranged such that the resistance heating elements 31 to 33 of the snow melting apparatus 1 are provided below the radio wave reflecting surface 53.
And the bidirectional conducting circuits 11 to 13 are buried, and the resistance heating elements 31 to 33 generate heat, so that the radio wave reflection surface 53 is formed.
There is no snow on top.

[0060] If a small amount of snow remains, such as a mottled pattern or a comb, and is not a flat surface, reflected radio waves may be scattered or scattered, which may hinder aircraft landing guidance. Therefore, conventionally, the snow was carefully removed by a staff member in an off-limits area, but the aircraft guidance device 53 of the present invention does not need to do so.

In order to apply the snow melting apparatus over a wide area, the above-mentioned △ -connected circuits may be connected in parallel. In addition to the above-described circuit configuration, a series circuit of a resistance heating element and a bidirectional conductive circuit may be connected in parallel and connected in this state, or a plurality of resistance heating elements may be connected to one bidirectional conductive circuit. Can be connected in parallel, and a circuit in which the components are connected in series can be connected in parallel.

The snow melting device and the aircraft guidance device have been described above. However, in order to form a heating device, the above-described resistance heating element is not buried, but is disposed, for example, between laminates made of woven fabric, non-woven fabric, or the like. Carpet by the usual method of
By laying this on the floor, a heating device can be configured.

[0063]

According to the snow melting apparatus of the present invention and the method of operating the same, the six thyristor elements are brought into conduction with a delay of 60 degrees, and are operated in six phases. Each thyristor element conducts when the applied voltage is zero. Also, when stopping, shut off in order with zero volts. Therefore, since no interfering electromagnetic waves are generated,

The present invention is suitable for melting snow in places where disturbing radio waves are disturbed by aircraft in airport facilities and for heating rooms such as operating rooms equipped with electronic equipment in hospital facilities.

The resistance heating element having the structure of the present invention is represented by Δ
By connecting, the current flowing through the switch becomes 1 / √3, so that the heat generation of the zero cross switch can be reduced to 1/3. Therefore, downsizing and long life can be achieved, which is very economical and has the effect of suppressing overcurrent.

[Brief description of the drawings]

FIG. 1 is a circuit diagram illustrating a snow melting apparatus according to an example of the present invention.

FIG. 2 is a timing chart for explaining the operation;

FIG. 3 is a diagram for explaining a current flowing through the snow melting device;
(1)

FIG. 4 is a diagram for explaining a current flowing through the snow melting device;
(2)

FIG. 5 is a diagram for explaining a current flowing through the snow melting device;
(3)

FIG. 6 is a diagram for explaining a current flowing through the snow melting device;
(4)

FIG. 7 is a diagram for explaining a current flowing through the snow melting device;
(5)

FIG. 8 is a diagram for explaining a current flowing through the snow melting device;
(6)

FIG. 9 is a circuit diagram showing a conventional snow melting apparatus.

FIG. 10 is a timing chart thereof.

FIG. 11 is a circuit diagram showing a conventional snow melting apparatus using a relay.

FIG. 12 is a diagram illustrating an aircraft guidance device according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Snow melting device 21-26 ... Thyristor element 31-33 ... Resistance heating element 11-13 ... Bidirectional conduction circuit 52 ... Antenna 53 ... Radio wave reflection surface 55 ... Aircraft guidance device

Continued on the front page (72) Inventor Tetsuo Morita 10-13 Minamimachi, Hanno City, Saitama Prefecture Inside Hanno Plant of Shindengen Kogyo Co., Ltd. ) Inventor Katsumi Mizuno F-term (reference) 4-8-33 Shibaura, Minato-ku, Tokyo 2D051 AA07 AB01 GA01 3K058 AA30 AA46 BA01 BA16 CA07 CA86 GA08 3L072 AA01 AB03 AB10 AC02 AD16 AE10 AG02 AG07

Claims (11)

[Claims] 1. A heating circuit is formed by serially connecting a bidirectional conduction circuit in which thyristor elements are connected in anti-parallel and a resistance heating element capable of generating heat by energization, thereby forming a heating circuit.
A snow melting device configured to embed a plurality of heating elements connected to apply a three-phase AC voltage under a road surface. 2. The snow melting apparatus according to claim 1, wherein said heating circuit is configured to connect at least one of said resistance heating elements in series to said one bidirectional conduction circuit. 3. The snow melting apparatus according to claim 1, wherein the plurality of heat generating circuits according to claim 2 are connected in parallel. 4. The heating circuit according to claim 1, wherein a plurality of the resistance heating elements are connected in parallel to one bidirectional conduction circuit.
The snow melting apparatus according to claim 1, wherein the snow melting apparatus is configured to be connected in series. 5. The operating method for controlling a snow melting apparatus according to claim 1, wherein said thyristor element is cut off from said two-way conduction circuit. An operation method in which a bidirectional conduction circuit whose applied voltage has become substantially zero volts can be sequentially turned on. 6. The operating method according to claim 5, wherein the bidirectional conduction circuit is sequentially shut off. 7. An antenna for transmitting an induced radio wave, and a radio wave reflecting surface which is constituted by a part of a road surface in an airport and reflects the induced radio wave, and wherein the antenna has a function of transmitting the guided radio wave. An aircraft guidance device, wherein the snow melting device according to claim 1 is buried under a road surface of the radio wave reflecting surface. 8. A heating circuit is formed by connecting a bidirectional conduction circuit in which thyristor elements are connected in anti-parallel and a resistance heating element capable of generating heat by energization in series to form a heating circuit.
A heating device configured to embed a plurality of heating elements that are connected to apply a three-phase AC voltage under a road surface. 9. The heating apparatus according to claim 8, wherein the heating circuit is configured to connect at least one of the resistance heating elements in series with one of the bidirectional conduction circuits. 10. A heating apparatus according to claim 8, wherein a plurality of said heat generating circuits according to claim 9 are connected in parallel. 11. The bidirectional conducting circuit 1 according to claim 1, wherein
9. The heating apparatus according to claim 8, wherein a plurality of the resistance heating elements connected in parallel to each other are connected in series.