JPS61266068A - Constant-current supplying circuit - Google Patents

Abstract

PURPOSE:To simplify the circuit configuration by connecting a current detector with the secondary winding of a transformer, further connecting a current transformer coupled electromagnetically with the secondary winding side, and turning ON and OFF a transistor of the primary winding side on the basis of the output of the detector. CONSTITUTION:A transformer 110 has the sole primary winding 103 and a plurality of secondary windings 211, 221. A current detector 226 is connected with the winding 221, and the winding of an electromagnetically coupled current transformer 225 is connected with the windings 211, 221. A controller 1 controls to turn ON and OFF a transistor 102 connected with the primary winding 102 on the basis of the output of a current detector 226.

Description

[Detailed Description of the Invention] [Summary] A constant current supply circuit according to the present invention is configured to supply constant current to a plurality of independent loads using one control system, and a constant current supply circuit according to the present invention is configured to supply a constant current to a plurality of independent loads using one control system. An element for detecting the supplied current as a feedback signal is provided only in a specific one. On the other hand, each current supply circuit is provided with a current transformer, and this current transformer is in a predetermined relationship with a current transformer provided in a specific current supply circuit so that the supply current of each current supply circuit can be controlled by the feedback signal. Connect with. As a result, in the multi-output constant current circuit, all outputs can be made constant current by a single control circuit, so the circuit configuration can be simplified.

[Industrial application field]

The present invention relates to an elevating circular constant current supply circuit.

[Conventional technology]

In order to obtain each independent constant current output in a conventional constant current circuit, a control circuit 1 proportional to the number of load resistors 213, 223, 233, as shown in FIGS.
1 to 13, pulse transformer 101.106°109.1
- transistor 102.104.107, transformer 110
.about.112 and two current supply circuits .about.23' were required.

[Problem that the invention seeks to solve]

As a result, the control circuits 11 to 13 used in each circuit
The transistors 102, 106, 107 and the transformers 101, 106, 109, 110 to 112 are also proportional to the number of loads, and the resistors 213, 223, 233 as current detection elements are also proportional to the number of loads, and are large in size and high. The price was.

[Means to solve the problem]

The present invention will be described with reference to FIG.

FIG. 1 is a circuit diagram of a constant current supply circuit according to the present invention when there are two loads, corresponding to FIG. 5 described above. In FIG. 1, one control circuit 1. One transistor 102
．． One DC power supply 104 and one main transformer 110 are connected as shown.

The main transformer 110 has a primary winding 103 and two independent secondary windings 211,221. After the secondary windings 211 and 221, there are load resistors 213 and 223, respectively.
A rectifier 212, 222 and a capacitor 214, 224 are connected to supply direct current to.

Each of the current supply circuits 21 and 22 has a current transformer 225.
The 0 windings are connected in series. Further, one current supply circuit 22 is provided with a resistor 226 as a current detection element.

Like the conventional one, the control circuit 1 includes a reference voltage generator, an amplifier, a pulse width control circuit, etc., and controls the pulse width of the pulse output that turns the transistor 102 on or off according to the signal from the resistor 226. change.

[For production]

The operation of the circuit shown in FIG. 1 will be described below.

First, the pulse output from the control circuit 1 is transmitted to the transistor 102.
Turn on. This causes the primary winding 1 of the main transformer 110 to
Power from the power supply 104 is stored in 03.

This accumulated power, when the transistor 102 is turned off,
It is transmitted to the respective independent secondary windings 211 and 221.

The transmitted power is rectified by a rectifier 212.222, smoothed by a capacitor 214.224, and a constant DC current is applied to a load 213.223.

This basic operation is the same as in the conventional case, but the signal waveforms of the circuit are shown in FIGS. 2(a) to 2(C). FIG. 2(a) shows the voltage between the collector and emitter of the transistor 102. FIG. 2 (bl is the current 1c flowing through the capacitor 214 or 224, and FIG. 2 (C1 is the current flowing through the rectifier 212 or 222).

In the circuit of FIG. 1, current supply circuits 21 and 22 are coupled by a current transformer 225. In the circuit of FIG. If the current transformer 2250 turns ratio is as shown in the diagram (nl:nz, and the flowing current is 1, If, then according to the law of equal ampere turns, n, I, = n
, I. Therefore, the current flowing from one secondary winding 211 of the main transformer 110 is proportional to the current flowing from the other secondary winding 221 by the current transformer 225, and is smoothed and regulated by the smoothing capacitors 214 and 224. As a currentized output current, it is supplied to the load resistor 213, 223.

This output current is detected by the resistor 226, and the control circuit 1 determines the conduction time of the transistor 102.
Constant current can be achieved.

〔Example〕

FIG. 3 shows an embodiment of the present invention. The constant current supply circuit shown in FIG.
3, and is an expanded version of the circuit shown in FIG. That is, current supply circuit 2
One winding of two current transformers 216 and 217 is connected in series to the other current supply circuit 22, and the other winding is connected to the other current supply circuit 22.
．． 23.

The operation is similar to that in FIG.

FIG. 4 shows another embodiment of the invention. The constant current supply circuit of FIG. 4 includes five independent load resistors 213, 223 .
233.243.253, but the current transformer 216.226.246°25
The connection relationship of 6 is different from that shown in FIGS. 1 and 3. That is, each current supply circuit 21. is connected to a specific current supply circuit 21 via a current transformer.
22.23 and 2L 24.25 are connected in sequence.

Current supply circuit 21 provided with current detection resistor 215
The current supply circuits are connected so that they are vertically balanced in the figure with . This circuit configuration is more suitable than the circuit shown in FIG. 1 or FIG. 3, especially when the load increases.

In the above embodiments, the constant current value of each current supply circuit can be set arbitrarily. That is, the secondary winding 211.221.23124L 2 of the main transformer 110
This can be realized by arbitrarily setting the ratio between 51 and the primary winding. As a result, the current transformation ratio of each current transformer is also changed.

When implementing the present invention, various modifications in addition to those described above may be adopted. For example, the circuit configuration shown in FIG. 3 and the circuit configuration shown in FIG. 4 can be combined as appropriate.

Note that even with these, the current provided to each load is electrically insulated and uniqueness is maintained. Further, a constant current can be supplied to the load as in the conventional case.

〔Effect of the invention〕

As mentioned above, the number of current transformers is (number of loads - 1) required, but only one current detection element is required, and the control circuit 1, transistor 102, and main transformer 116 are also Only one piece is enough. Therefore, the circuit configuration is significantly simplified, and the device can be made smaller and lower in price.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the principle of the present invention, FIG. 2 is a signal waveform diagram of the circuit shown in FIG. 1, and FIGS. 3 and 4 are constant current supply circuits as other embodiments of the present invention. Figures 5 and 6 are diagrams showing conventional constant current supply circuits,
It is. (Explanation of symbols) 1... Control circuit, 101... Pulse transformer, 102... Transistor, 104... Power supply, 110... Main transformer, 21-25... Current supply circuit, 212, 222.232.242.252... Rectifier, 214, 224.234.244.254... Capacitor, 216, 226.246.256... Current transformer. Fig. 1 Fig. 5 A diagram showing a conventional constant current supply circuit Fig. 2 A diagram showing a signal waveform diagram Fig. 3 A diagram showing an embodiment of the present invention Fig. 4 A diagram showing an embodiment of the present invention

Claims (1)

[Claims] 1. A transformer having a single primary winding and multiple secondary windings (
110), a current detector (22) connected to one of the plurality of secondary windings;
6), a current transformer (225) in which electromagnetically coupled windings are connected to different secondary windings; A constant current supply circuit comprising: a control circuit (1) for controlling on/off of a transistor (102) connected to a transistor (102). 2. Claim 1, wherein one winding of each of the plurality of current transformers is connected in series to the specific current supply circuit, and each of the other windings is connected to another current supply circuit. The constant current supply circuit according to item 1. 3. One winding of two current transformers is connected in series to each of the plurality of current supply circuits, and the other winding is connected in an adjacent current supply circuit around the specific current supply circuit. The constant current supply circuit according to claim 1, wherein the constant current supply circuit is provided so as to be connected in series.