JP3184437B2 - DC switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC switch suitable for opening and closing a DC power distribution system.

[0002]

2. Description of the Related Art Conventionally, indoor wiring such as electric lamps and motive power is supplied from an AC power supply. However, with the practical use of photovoltaic power generation and fuel cells, a DC power supply is being used. But,
At present, there is no appropriate DC switch interposed in a DC power supply indoor wiring or the like.

[0003] For example, as a switch used for blinking an electric light, a small switch has been widely used for AC, but when it is used for DC, its range is limited to an extremely small current. In the case of DC, the current is zero like AC
Because there is no point in time when the mechanical contact is opened, an arc is generated when the mechanical contact is opened, so that the circuit cannot be opened or the contact is burned.

[0004]

However, in a DC power supply system such as a photovoltaic power generator or a fuel cell, it is essential to have a DC switch of, for example, a wall-embedded type which can open the power distribution system (for example, 10A to 20A). . However, at present, there is no DC switch of an embedded wall type that meets this demand. For this reason, in practice, a device such as a DC breaker is used as a substitute, but this DC breaker is equipped with a trip circuit. It requires power to operate and has poor usability.

It is an object of the present invention to solve the above-mentioned problems and to provide a DC switch suitable for opening and closing a DC power distribution system and capable of constructing a switch having a relatively large DC rated current.

[0006]

In order to achieve the above object, a DC switch according to the first aspect of the present invention includes a DC switch having a manual operation switch having an interlocking mechanical contact, and a DC switch having a positive side and a negative side. Forced commutation using electrically connected input and output terminals, a main thyristor inserted between the plus or minus bus between the input and output terminals, and an auxiliary thyristor to turn off the main thyristor Circuit, and a gate trigger voltage circuit for a gate circuit of the main thyristor and the auxiliary thyristor, wherein the manually operated switch is inserted into a positive bus or a negative bus between the input / output terminals as an interlocking mechanical contact. a first contact that is, a third contact which is inserted in the gate circuit of the main thyristor, inserted into the gate circuit of the auxiliary thyristor Second; and a contact which is, at the time of its entry operation, the first contact ON, perform sequentially the third contact ON, also at the time of switching operation, the third contact OFF, a second contact ON, first Are sequentially turned off.

Combining a manually operated switch having at least three interlocking mechanical contacts with a main thyristor,
In the case of "ON" operation, the main thyristor is turned on after the first contact inserted between the input / output terminals is entered, and in the case of "OFF" operation, the second contact inserted in the gate circuit of the auxiliary thyristor is turned ON. When turned on to activate the commutation circuit, a current flows in the main thyristor in the opposite direction. When the current flowing through the main thyristor becomes zero (main thyristor is turned off), the first mechanical contact is opened. Therefore, even in the case of direct current, the first mechanical contact can be easily cut off without causing an arc or burning out the contact when opening the first mechanical contact. The second contact of the manual operation switch is turned off after the auxiliary thyristor is turned on at the time of the “off” operation, or
Alternatively, at the time of the "ON" operation, the third contact is turned ON and returned to OFF before the main thyristor is turned on.

According to a second aspect of the present invention, in the DC switch according to the first aspect, the gate trigger voltage circuit is constituted by a voltage dividing circuit provided between the positive bus or the negative bus, while the energy saving circuit is constituted. A semiconductor switch is provided in series in the voltage dividing circuit, and the semiconductor switch is connected at least from the end of the on-operation to the off-operation by a fourth contact provided as one of the mechanical contacts interlocked with the manual operation switch. A period until the start, for example, immediately after the third contact ON at the time of the ON operation, to the third contact OF at the time of the OFF operation
The period immediately before F or immediately before the second contact is turned on is O
It is configured to perform FF.

After the third contact is turned on and the main thyristor is turned on at the time of the "ON" operation, the current supply to the unnecessary voltage dividing circuit is cut off, and thereafter, the period until the "OFF" operation is performed. In other words, the interruption is continued until the current supply to the voltage dividing circuit is required again to turn on the auxiliary thyristor. Therefore, unnecessary power consumption in the voltage dividing circuit during the period of supplying to the load is avoided, and power and heat generation are reduced. Therefore, it is safe even if it is configured as, for example, a DC switch or the like embedded in a wall.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment shown in the drawings.

The DC switch shown in FIG. 1 includes a manually operated switch 1 which is manually turned on and off from the outside of a casing, and a DC input terminal A connected to a DC power supply system. , B and DC output terminals C and D connected to a DC load L.

SW1, SW2 and SW3 are mechanical contacts of the manually operated switch 1, here, mechanical contacts of a rotary switch.

DC input terminals A and B connected to a DC power supply system and DC output terminals C and D connected to a DC load L
Are connected by buses 2 and 3, and the buses 2 and 3
The mechanical contact SW1 of the manual operation switch 1 is inserted into one positive bus 2, and the thyristor 4 (main thyristor SCR1), which is a semiconductor switch, has an anode in the other negative bus 3 as an output terminal. It is inserted on the D side.

An auxiliary thyristor 6 is provided in parallel with the main thyristor 4 to constitute a forced commutation circuit 5 for turning off the main thyristor 4. That is, a series circuit composed of a resistor R1, an inductor L1 and a capacitor C1 is connected between the anode-side buses 2 and 3 of the main thyristor 4, and a connection point P between the resistor R1 and the inductor L1 is connected.
The anode of the auxiliary thyristor 6 is connected to 1, and the cathode of the auxiliary thyristor 6 is connected to the cathode of the main thyristor 4.

Furthermore, in order to create a firing voltage for the gate of the main thyristor 4 and the gate of the auxiliary thyristor 6,
A voltage dividing circuit 7 including resistors R2 and R3 is provided as a gate trigger voltage circuit between the buses 2 and 3 on the cathode side of the main thyristor 4, and a voltage at a connection point P2 of the voltage dividing circuit 7 The gate of the auxiliary thyristor 6 is provided via a contact SW2, and the gate of the auxiliary thyristor 6 is provided via a contact SW2.

Next, the operation will be described.

When the manual operation switch 1 is turned on, the first contact SW1 is turned on and the third contact SW3 is turned on in one operation.
In one operation, the third contact SW3 = OFF, the second contact SW
2 = ON and the first contact SW1 = OFF are sequentially performed. Here, the second contact SW2 is turned off after turning on the auxiliary thyristor at the time of the "off" operation, but the third contact SW3 is turned off at the time of the "on" operation as shown in FIG. It may be turned on and returned to off before the main thyristor is turned on.

First, the case where the DC switch is turned on will be described. In FIG. 2, when the manual operation switch 1 is depressed to the "ON" position in one operation, the mechanical contact SW1 is first turned on.
Turns on (time T1). As a result, a DC voltage is applied to the voltage dividing circuit 7. Then, the main thyristor 4 (SCR
The contact SW3 in the gate circuit of 1) is turned on (time T).
3) As a result, the voltage at the connection point P2 of the voltage dividing circuit 7 is applied to the gate of the main thyristor 4. Therefore,
The main thyristor 4 is turned on, the input terminals A, B and the output terminals C, D conduct, the DC voltage appears at the output terminals C, D, and the current I flows through the load L.

Next, a case where the DC switch is turned off will be described. In FIG. 2, when the manual operation switch 1 is pressed to the opposite side and is set to the "OFF" position by one operation, first, the contact SW3 in the gate circuit of the main thyristor 4 (SCR1) is turned off.
At the same time or subsequently, the contact SW2 in the gate circuit of the auxiliary thyristor 6 is turned on (time T5). Therefore, the auxiliary thyristor 6 (SCR2)
Is turned on, and the electric charge previously stored in the capacitor C1 with the polarity shown in the figure flows from the connection point P1 through the auxiliary thyristor 6 as a discharge current i in a direction to cancel the current I of the main thyristor 4. Here, the peak value of the discharge current i is set to be larger than the peak value of the current I of the main thyristor 4, and when the discharge current i becomes equal to the current I of the main thyristor 4, the main thyristor 4 is turned off. I do. After this, the charging current flows through the capacitor C1 with the polarity reversed in the route of SW1, loads L, C1, L1 and SCR2, but becomes zero when charging is completed.
Since the auxiliary thyristor 6 is turned off, the circuit currents are all zero.

After the above, that is, after the load current becomes zero, the mechanical contact SW1 is turned off (time T).
6). Therefore, even when the mechanical contact SW1 is turned off, no arc is generated between the contacts, and it is possible to easily and completely cut off the current supply from the input terminal to the output terminal.

FIG. 3 shows another embodiment. This is an improvement of the above, and the voltage dividing circuit 7 as the gate trigger voltage circuit includes a resistor R formed by connecting a plurality of resistors in series.
3 and a series circuit of a Zener diode ZD,
The voltage dividing point, that is, the connection point P2, is connected to a contact SW inserted in series with the gate of each of the thyristors 4 and 6 via a resistor R4.
2, SW3 is connected to a connection point P3. Further, in order to constitute the energy saving circuit 8 for blocking the current flowing through the resistor R3 of the voltage dividing circuit 7 except when necessary, the energy saving circuit 8 is connected in series with the resistor R3 of the voltage dividing circuit 7 (in this example, the connection point P2 and the resistor R3).
), A switching transistor Tr1 is inserted, and its base is connected to the positive bus 2 via a series circuit including a resistor R5 and a mechanical contact SW4 of the manually operated switch 1. This contact SW4 is also a mechanical contact of a rotary switch that works together with the contacts SW1 to SW3, and turns off after the "on" operation of the manual operation switch 1 is completed, as shown in FIG. The timing is set so as to return to ON beforehand. Note that a series circuit of an inductor L2 and a capacitor C2 is connected in parallel to the contact SW4 for energy absorption. In addition, plus bus 2 and minus bus 3
Between them, a surge protection element 9 is provided immediately after the first contact SW1.

Next, the operation of the DC switch shown in FIG.
This will be described with reference to FIG.

First, the case where the DC switch is turned on will be described. In FIG. 4, when the manual operation switch 1 is depressed to the "ON" position by one operation, the mechanical contact SW1 is first turned ON.
(Time T1). As a result, the voltage E of the DC power supply system (for example, 210 V, 10 A) is applied to the voltage dividing circuit 7 as it is. Subsequently, the gate contact SW2 of the auxiliary thyristor 2 of the forced commutation circuit 5 is returned to OFF in advance (time T
2) Then, the contact SW3 in the gate circuit of the main thyristor 4 (SCR1) is turned on (time T3). At this time, the contact SW4 of the energy saving circuit 8 is still ON.
Therefore, the transistor Tr1 is in the ON state.
Therefore, the voltage at the connection point P2 of the voltage dividing circuit 7 is applied to the gate of the main thyristor 4 through the resistor R4 and the contact SW3. Therefore, the main thyristor 4 turns on,
As a result, the input terminals A and B and the output terminals C and D conduct, a DC voltage appears at the output terminals C and D, and a current I flows through a load L, for example, a fluorescent lamp. Thereafter, the contact SW4 of the energy saving circuit 8 is turned off, and the transistor Tr1 is turned off.
Since the FF state is set, the current flowing through the resistor R3 is cut off, and wasteful power consumption of the voltage dividing circuit 7 during the period in which the load L is used is avoided.

Next, a case where the DC switch is turned off will be described. In FIG. 4, when the manual operation switch 1 is pressed to the opposite side and set to the "OFF" position by one operation, first, the contact SW4 of the energy saving circuit 8 is turned ON, and the transistor T
r1 is turned on, and the voltage dividing circuit 7 is energized (time T8). Subsequently, the contact SW3 in the gate circuit of the main thyristor 4 (SCR1) is turned off (time T4), and simultaneously or subsequently, the contact SW2 in the gate circuit of the auxiliary thyristor 6 is turned on (time T5). . Accordingly, the auxiliary thyristor 6 (SCR2) is turned on, and the electric charge previously stored in the capacitor C1 with the polarity shown in the drawing has the LC resonance current in the direction to cancel the current I of the main thyristor 4 through the auxiliary thyristor 6 from the connection point P1. Flows as i. Here, the peak value of the LC resonance current i is set to be larger than the peak value of the current I of the main thyristor 4, and when the LC resonance current i becomes equal to the current I of the main thyristor 4, the main thyristor 4 Turns off.
After that, the capacitor C1 has SW1, load L, C1, L
The charging current flows with the polarity reversed in the route of SCR1 and SCR2, but becomes zero when charging is completed, and the auxiliary thyristor 6 is turned off, so that all circuit currents become zero.

After the above, that is, after the load current becomes zero, the mechanical contact SW1 is turned off (time T).
6). Therefore, even when the mechanical contact SW1 is turned off, no arc is generated between the contacts, and it is possible to easily and completely cut off the current supply from the input terminal to the output terminal.

In the case of the DC switch shown in FIG. 3, the current flowing through the resistor R3 of the voltage dividing circuit 7 is controlled by the operation of the energy-saving circuit 8 at one time when the manual operation switch 1 is turned on and off. Only, that is, when a gate voltage required to turn on the main thyristor 4 is generated (time T1
To T7) and the gate voltage necessary to turn on the auxiliary thyristor 6 (time T8 to T6), the power is consumed only very little, and the heat generation can be kept small. it can.

In the above embodiment, the OFF period of the contact SW4 is from the time when the "ON" operation of the manual operation switch 1 is completed (time T7) to the time when the "OFF" operation is started (time T8). At least this load usage period (time T7
-T8) is sufficient. For example, the OFF period of the contact SW4 is started immediately after the time T3 at which the main thyristor 4 is turned on when the "ON" operation is completed (at the time T3).
7), and the OFF period of the contact SW4 ends at the time T when the auxiliary thyristor 6 is turned on from the start of the “OFF” operation (time T8).
5 can be set arbitrarily up to immediately before.

[0028]

As described above, according to the first aspect of the present invention, a manually operated switch having at least three interlocking mechanical contacts is combined with a main thyristor to turn on.
At the time of operation, the main thyristor is turned on after the first contact inserted between the input and output terminals enters, and at the time of "off" operation,
The second contact inserted into the gate circuit of the auxiliary thyristor is
N, the commutation circuit is activated, and a current in the opposite direction is caused to flow through the main thyristor, whereby the first mechanical contact is opened when the current flowing through the main thyristor becomes zero (main thyristor OFF). You. Therefore, even in the case of direct current, the first mechanical contact can be easily cut off without causing an arc or burning out the contact when opening the first mechanical contact. The second contact of the manual operation switch is turned off after the auxiliary thyristor is turned on at the time of the “off” operation, or the third contact is turned on at the time of the “on” operation.
Then, the main thyristor is turned off before it is turned on.

In addition, the circuit breaker can be made smaller than a breaker containing an iron box, can be operated with a lighter force than the breaker, and can be constructed with a relatively large DC rated current.

Next, according to the second aspect of the present invention, the current supply to the unnecessary voltage dividing circuit is continuously cut off at least during a period from the end of the ON operation to the start of the OFF operation. Therefore, unnecessary power consumption in the voltage dividing circuit during the period of supplying to the load is avoided, and power and heat generation are reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a circuit configuration of a DC switch according to an embodiment of the present invention.

FIG. 2 is a timing chart showing the mechanical contacts of the DC switch of FIG. 1 and the operation of the thyristor.

FIG. 3 is a diagram showing a circuit configuration of a DC switch according to another embodiment of the present invention.

FIG. 4 is a timing chart showing the mechanical contacts of the DC switch of FIG. 3 and the operation of the thyristor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Manual operation switch 2 Positive bus 3 Minus bus 4 Main thyristor 5 Commutation circuit (arc extinguishing circuit) 6 Auxiliary thyristor 7 Voltage dividing circuit (gate trigger voltage circuit) 8 Energy saving circuit 9 Surge protection element A, B DC input terminal C , D DC output terminal C1, C2 Capacitor L1, L2 Inductor P1, P2, P3 Connection point R1 to R5 Resistance ZD Zener diode SW1, SW2, SW3, SW4 Mechanical contact of manually operated switch Tr1 Switching transistor L Load

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hidenori Takahashi 6-8-19 Shimomeguro, Meguro-ku, Tokyo Inside Meiko Corporation (72) Inventor Fumio Watanabe 4-46-8 Nukii, Nerima-ku, Tokyo Meikosho (72) Inventor Atsuyasu Imai 4-46-8 Nukii, Nerima-ku, Tokyo Meiko Shoji Co., Ltd. (56) References JP-A-61-231835 (JP, A) JP-A-58-78334 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01H 33/59 H03K 17/73

Claims (2)

(57) [Claims] 1. A manually operated switch having an interlocked mechanical contact, an input terminal and an output terminal electrically connected to each other on the plus side and the minus side, and a positive bus between the input and output terminals. A main thyristor inserted into the minus bus, a forced commutation circuit configured using an auxiliary thyristor to turn off the main thyristor, and a gate trigger voltage circuit for a gate circuit of the main thyristor and the auxiliary thyristor; The manual operation switch includes a first contact inserted into a plus bus or a minus bus between the input / output terminals as a mechanical contact to be interlocked, and a first contact inserted into a gate circuit of the main thyristor .
3 contacts and inserted into the gate circuit of the auxiliary thyristor
A second contact , when the switch is turned on, the first contact is turned on, and the third contact is turned on.
Third contact OFF, second contact ON, first contact OFF
The DC switch is characterized in that it is performed in order. 2. The semiconductor device according to claim 1, wherein the gate trigger voltage circuit comprises a voltage dividing circuit provided between the plus bus or the minus bus, and a semiconductor switch is provided in series in the voltage dividing circuit to constitute an energy saving circuit. The semiconductor switch is configured to turn off at least a period from the end of the on-operation to the start of the off-operation by a fourth contact provided as one of the mechanical contacts interlocked with the manual operation switch. The DC switch according to claim 1, wherein