JPH0766733B2 - Excitation circuit of relay - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an exciting circuit of a relay used in a battery vehicle or the like, and more specifically, a plurality of relays are excited by only one switching element. is there.

[Prior art]

Fig. 4 shows the excitation circuit of a general relay. In FIG. 4, the exciting coil 1 and the transistor (switching element) 3 of the relay are inserted in series between the high voltage side V1 and the low voltage side V0 of the power supply. Also, the diode 7 and the resistance element 6
Are connected in parallel with the exciting coil 1.

The transistor (switching element) 3 is a chopper control element that adjusts the exciting current by opening and closing the V1-V0 power supply circuit in a short cycle, and also operates the exciting coil (in the chopper control state) -not operates (for a long time). It is an element that also controls the disconnection state. That is, when the transistor 3 is turned on, the exciting current flows through the exciting coil. The movable plate (having a movable contact) is attracted to the iron core of the electromagnet to connect the movable contact by the electromagnetic force generated by the ON state or the intermittent state in a short cycle, or is released when the OFF time is long. When the transistor 3 is turned off, the exciting current is cut off.

In the above, in order to protect the transistor 3 from the reverse voltage (surge voltage) generated when the exciting current is cut off, the current due to the reverse voltage is circulated by the circulation circuit composed of the diode 7 and the resistance element 6. . Here, the resistance element 6 is an element that shortens the separation time of the relay (which is the time until the current is effectively interrupted by the separation of the fixed contact and the movable contact). That is, when the excitation is finished and the relay is separated (the long-term disconnection state),
The resistor 6 converts the reflux current into Joule heat and attenuates it, thereby shortening the separation time.

However, in the exciter circuit of such a relay, during chopper control, even when the transistor 3 is switched at high speed (above the short cycle), the exciting current is interrupted and the current recirculates, so that the power loss caused by the resistor 6 is reduced. I can't ignore it.

Therefore, for example, Japanese Patent Application Laid-Open No. 54-131769 discloses an exciting circuit that simultaneously reduces the power loss in the return circuit during chopper control and shortens the drop-off time. The conventional excitation circuit shown in this publication is different from the main circuit including an excitation coil and a switching element in that the first circuit includes a one-way resistance element that forms a closed circuit with the excitation coil when the relay is turned on.
And a second return circuit including a resistance element and a unidirectional element that form a closed circuit with the exciting coil when the relay is disconnected.

Specifically, in FIG. 5, the exciting coil 1 and the current path between the main electrodes of the transistor 3 are connected in series, and are interposed between the high potential terminal + V and the low electronic terminal GND. A pulse signal VI1 for controlling energization of the exciting coil 1 is introduced into the base of the transistor 3. Further, the exciting coil 1 has a freewheeling diode 7
A series circuit including a resistance element 61 and the exciting coil 1 is connected so as to form a closed circuit, and the resistance element 61 is connected in parallel with a current path between main electrodes of a transistor 90 controlled by the transistor 91. There is. The transistor 91 is designed to be controlled by the control signal VI2 for switching the return circuit.

FIG. 6 shows a timing chart of the pulse signal VI1 and the control signal VI2. At time t ₀ , when the relay input signal is input to the control unit (not shown) (start of excitation), the pulse signal V1 and the control signal VI2 are input. Rises to H level. The pulse signal VI1 has an H level during the period t ₀ -t ₁ , and makes the transistor 3 continuous. Further, the transistor 9 is rendered conductive by the control signal VI2 of H level. As a result, a large exciting current is passed through the exciting coil 1 to reliably attract the movable plate of the relay.

Pulse signal VI1 becomes t ₁ subsequent pulse train in response to a command from the controller. Transistor 3 This t ₁ after the pulse signal VI1 is being chopper driven flow the small excitation current capable of maintaining a suction state of the movable plate to the exciting coil 1.

Control signal VI2 holds H level until time t ₂ (excitation termination) which is No. relay away落信inputted. During the period t ₀ -t ₂ in which the control signal VI2 is at H level, the transistor 9 is conductive and the resistance element 61 is short-circuited. Therefore, the reverse voltage (voltage having a reverse polarity to the power supply voltage of the high potential terminal + V) generated at both ends of the exciting coil 1 by the transistor 3 which operates as a chopper during the period t ₁ -t ₂ is forwarded by the diode 7 due to the reverse voltage. It is biased and gently deenergized in the closed circuit (first freewheeling circuit) with the transistor 9, diode 7 and exciting coil 1.
Since there is no resistance component in this closed circuit, there is almost no power loss.

Transistor 3 at time t ₂ when the control signal VI2 falls becomes non-conductive. At the same time, the transistor 9 shifts to the non-conducting state. Therefore, the reverse voltage generated in the exciting coil 1 at the time t ₂ is deenergized in a short time by the closed circuit (second return circuit) with the resistance element 61, the diode 7 and the exciting coil 1.

[Problems to be solved by the invention]

Now, consider controlling a plurality of relays based on the circuit configuration as shown in FIG. In the exciting circuit for controlling the plurality of relays, a plurality of exciting coils are connected to one switching element, and first and second return circuits are provided for each exciting circuit.

However, in the configuration in which a plurality of exciting coils are simply connected to the current path between the main electrodes of the switching element as described above, when the exciting coils are chopper-controlled simultaneously or sequentially chopper-controlled, However, if the chopper control times overlap, there are the following inconveniences.

That is, when the second exciting coil that follows is chopper-controlled before the first exciting coil that is chopper-controlled in advance is not terminated (transistor 9 is non-conductive),
Since the reverse voltage generated in the first exciting coil at the end of the excitation of the first exciting coil is also superimposed on the second exciting coil,
By the action of the first return circuit connected to the second exciting coil, the current flowing in the second exciting coil is increased, and a high current flows unnecessarily in the second exciting coil, resulting in a large power loss. Become.

The present invention has been made in view of such an actual situation, and in sequentially exciting a plurality of relays by providing an overlap time, in a subsequent relay due to a reverse voltage generated when the preceding relay is disconnected, It is an object of the present invention to provide an exciting circuit of a relay that accurately excites each relay while avoiding an increase in the power loss of.

[Technical means for solving problems]

In order to solve the above-mentioned problems, the excitation circuit of the relay of the present invention includes a switching element driven by a pulse signal, a plurality of excitation coils connected in series to a current path between main electrodes of the switching element, Each control element for connecting and disconnecting a current path formed by each exciting coil and the switching element based on a control signal, and a current path between main electrodes of the switching element to form a closed circuit with the exciting coil energized by each control element. From each series circuit of unidirectional elements, each first return circuit consisting of unidirectional elements connected in series, and a resistance element and a unidirectional element interposed between a connection point of the exciting coil and the control element and a reference potential point And each of the second reflux circuits.

In the exciting circuit of the relay having the above-described configuration, each first return circuit deactivates the reverse voltage generated in the exciting coil immediately after the control element becomes non-conductive during chopper control without power loss. In each of the second reflux circuits, the control element is made non-conductive at the end of the excitation, so that a current path formed of a current path between the excitation coil and the main electrodes of the switching element, a series circuit of a resistance element and a unidirectional element is formed. Forms a closed circuit to deactivate the reverse voltage generated in the exciting coil in a short time.

According to the second return circuit, the second return circuit forms a closed circuit with the switching element when the reverse voltage is deenergized. That is, the current based on the generated reverse voltage is drawn from the current path between the main electrodes of the switching element by the unidirectional element of the second reflux circuit, then flows through the resistance element and is consumed as Joule heat. Therefore, even if the succeeding exciting coil is chopper-controlled before the excitation of the preceding chopper-controlled exciting coil is completed, the reverse voltage-dependent current flowing to the succeeding exciting coil hardly flows. It is possible to avoid an unnecessarily high increase in current loss to the subsequent exciting coil due to the exciting coil.

〔Example〕

FIG. 1 is a configuration diagram showing an exciting circuit of a relay according to an embodiment of the present invention. The exciting circuit includes exciting coils 1a and 1b operated by a 12V DC power source 20 and exciting coils 1a and 1b. NPN-type transistor 3 connected in series to the low-voltage side and controlled by pulse signal VI1, PNP-type transistor 9a connected in series to the high-voltage side of exciting coil 1a, and high-voltage side of exciting coil 1b PNP transistor 9b, NPN transistor 90a controlled by control signal VI2 to drive transistor 9a, and NPN transistor 90b controlled by control signal VI3 to drive transistor 9b.
And a first freewheeling circuit including a freewheeling diode 8a connected in parallel to the exciting coil 1a and the transistor 9a, and a freewheeling diode 8b connected to the exciting coil 1b and the transistor 9b.
A first freewheeling circuit including a second freewheeling diode and a resistance element that are connected in parallel to the exciting coil 1a and the transistor 3 to form a closed circuit when the transistor 9a is off.
The freewheeling circuit 6a, the second freewheeling circuit 6b which is similarly connected in parallel to the exciting coil 1b and the transistor 3, and the digital computer 50.

The digital computer 50 inputs a signal for closing the relay 1a, a signal for disconnecting it and a signal for closing the relay 1b, a signal for disconnection from the outside, and gives the pulse signal VI to the base of the transistor 3.
1. It outputs a control signal VI2 applied to the base of the transistor 90a and a control signal VI3 applied to the base of the transistor 90b. Each of the pulse signals VI1, VI2, and VI3 is a high level signal (hereinafter referred to as an H signal) to turn on each transistor, and a low level signal (hereinafter referred to as an L signal) is turned off.

The operation of the excitation circuit of the relays 100a and 100b will be described below.
This will be described with reference to FIGS. FIG. 2 is a flowchart showing the processing in the digital computer 50, and FIG. 3 is a pulse signal VI1, a control signal VI2, a control signal.
6 is a timing chart showing changes in VI3.

As shown in FIG. 2, the digital computer 50 starts execution of control signal processing in the circuit of this embodiment when the power is turned on (S100). Next, set the initial state (S1
02).

Now, the input signal of the relay 100a is the digital computer 50.
Is input to (S104), the control signal V of the transistor 90a
Let I2 be an H signal (S106, time t ₀ ). Therefore, the transistors 90a and 9a are turned on. That is, the first return circuit 8
Switch to side a. Next, it is determined from the movable plate suction determination flag whether or not the movable plate has already been attracted to the electromagnet (1 if already attracted, φ if not yet attracted).
(S114), when the content of the flag is φ, a predetermined time
Continue the H1 signal of VI1 and pass a large exciting current (S116,
t ₀ −t ₁ ).

At this time, an exciting current flows through the exciting coil 1a through the transistor 9a and the transistor 3, and the movable plate is attracted to the iron core of the electromagnet by the electromagnetic force generated by the exciting current.

When the intermittent H signal of the pulse signal VI1 of the transistor 3 ends (the movable plate suction flag is set to 1 at this time), the movable plate of the relay 100a is held by the iron core of the electromagnet and the movable contact and the fixed contact are connected. Has been done. After that, a relatively small electromagnetic force is sufficient to continue the holding operation,
Pulse signal VI1 of the transistor 3 becomes a chopper signal (S118, t ₁ ~).

The chopper signal is a repetition of an H signal and an L signal having a constant duty cycle, and the transistor 3 turns on and off at a constant cycle to perform chopping. Here, the current due to the reverse voltage generated by the chopping of the transistor 3 circulates in the low voltage side of the exciting coil 1a, the first circulation circuit 8a, and the closed circuit formed by the transistor 9a. The same applies to the relay 100b side.
(S108 to S118) Now, when the relay 100a is excited first and the relay 100b is subsequently excited, when the disconnection signal of the relay 100a is input to the digital computer 50 (S120), the transistor 90a is activated.
Switch the control signal VI2 as L signal (S122, t _5), the transistor 90a, thus the second back circuit 6a side transistor 9a is turned off.

The second return circuit 6a forms a closed circuit with the transistor 3 and draws in a current based on the reverse voltage generated in the exciting coil 1a when the transistor 9a is turned off, and at that time, the current is consumed as Joule heat by the resistance element. Let For this reason,
The reverse voltage-dependent current that flows to the exciting coil 1b hardly flows. The reverse voltage-dependent current consumed as Joule heat is deenergized during the conduction period of the transistor 3 based on the pulse signal VI1. When the exciting coil 1b is finished to be excited, the pulse signal of the transistor 3 is set so that the transistor 3 is turned off after the transistor 9b.
VI1 to have a slow L signal by one-pulse partial from the control signal VI3 transistor 9b (step _{130, T = t 6 ~t 7} ).

〔The invention's effect〕

According to the exciter circuit of the relay of the present invention, when the reverse voltage from the preceding exciting coil is deenergized, the second reflux circuit that forms a closed circuit with the switching element is provided. Is drawn from the current path between the main electrodes by the unidirectional element of the second reflux circuit, then flows through the resistive element and is consumed as Joule heat. Therefore, even if the succeeding exciting coil is chopper-controlled before the excitation of the preceding chopper-controlled exciting coil is completed, the reverse voltage-dependent current flowing to the succeeding exciting coil hardly flows. It is possible to avoid an unnecessary increase in current loss to a subsequent exciting coil due to the exciting coil, and to control a plurality of exciting coils with a chopping switching element.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an excitation circuit of a relay according to the present invention. FIG. 2 is a flow chart showing the order of processing of the digital computer 50 in the embodiment circuit. FIG. 3 is a timing chart showing changes in the pulse signal VI1, the control signals VI2 and VI3. FIG. 4 is a block diagram showing a general excitation circuit. FIG. 5 is a block diagram showing a conventional excitation circuit. FIG. 6 is a timing chart showing the operation of FIG. 1 is an exciting coil, 3 is a switching element, 5 is a control unit,
6a and 6b are second freewheeling circuits, 8a and 8b are freewheeling diodes (first
Reflux circuit), 9a and 9b are control elements. It should be noted that constituent elements that operate commonly or equivalently in each figure are denoted by common reference numerals.

Claims (1)

[Claims] 1. A switching element driven by a pulse signal, a plurality of exciting coils connected in series in a current path between main electrodes of the switching element, and a current path formed by each exciting coil and the switching element. Each control element that is intermittent based on a control signal, and each unidirectional element that is connected in series to the current path between the main electrodes of the switching element to form a closed circuit with the excitation coil energized by each control element. A first return circuit and each second return circuit including a series circuit of a resistance element and a unidirectional element interposed between a connection point of the exciting coil and the control element and a reference potential point are provided. An exciting circuit for a relay, which is characterized in that