JPS63290490A - Power receiving device for home bus system - Google Patents

Abstract

PURPOSE:To reduce a cost by detecting a signal current by using a transformer, making it a high impedance against a transmission signal to miniaturize the transformer. CONSTITUTION:When a bipolar signal is superimposed on a home bus 2, a signal current tends to flow into a power receiving device 1 through a terminal 7 in the case of a positive-polarity pulse. When a signal current which is a positive-polarity pulse flows through the primary winding 4a of a transformer 4, an inductive current flows in its secondary winding. This causes the collector- emitter voltage of a transistor 3a to rise, to expel the signal current which is the positive-polarity pulse of bipolar signal that has been apt to flow into the primary winding 4a of the transformer 4. In the case of a negative-polarity pulse of the bipolar signal, the collector-emitter voltage of the transistor 3 is dropped, and a signal current which is a negative-polarity pulse that has been apt to flow out from the primary winding 4a of the transformer 4 is drawn back.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention 8A relates to a power receiving device for operating a terminal connected to a home bus or a part of a circuit inside the terminal using a DC power supply superimposed on the home bus. It is something.

Conventional technology Conventionally, when receiving DC power superimposed on a home bus, a choke transformer and a capacitor were used to receive the power.

FIG. 3 shows an example of a conventional power receiving device.

21 is a home bus, and a power supply device 22 superimposes power on the home bus 21. 23 is a power receiving device consisting of a chiller coil 23& and a capacitor 23b;
It receives the DC power superimposed on the home bus 21 and supplies power for the communication terminal 24 to operate.

The communication terminal 25 is supplied with power from an external power supply device 26.

FIG. 4 is an equivalent circuit for analyzing the waveform distortion of the communication bipolar code transmitted to the home bus 11 of FIG. 3 in the conventional embodiment. 31 is a signal source Ks of a bipolar code transmitted by the communication terminal 24 or 26. 32 is the output impedance R8 of the communication terminal 24 or 25 during transmission. Bipolar code signal source 31
and the output impedance 32Vi are connected in series to the choke coil 23 & of the power receiving device 23 through the home bus 21.
connected to. Therefore, the bipolar code output by the bipolar code signal source 31 is differentiated by the output impedance 32 and the inductance L of the choke coil 231L.

FIG. 5 shows an example of the output waveform of the bipolar code signal source 31. FIG. 6 shows an example of a signal waveform at both ends of the choke coil 231L of the equivalent circuit shown in FIG. 4, that is, on the home path. As shown in FIG. 6, the signal waveform of the bipolar code on the home path becomes a differentiated waveform, which is inconvenient for normal reception.

The factors by which this waveform is differentiated are the output impedance 32 of the equivalent circuit shown in FIG. 4 and the inductance L of the choke coil 23&. The time constant τ is expressed by the following equation.

t3 From the above formula, the smaller R8 and the larger L, the larger τ becomes,
The differential of the bipolar code becomes small, and the signal is transmitted while remaining close to the original signal waveform.

Problems to be Solved by the Invention Such conventional power receiving devices have the following problems.

The inductance of the choke coil is, for example, 960
In the case of a bipolar code with a transmission rate of 0 bps and a duty of 60%, a value of ts o o mH or more is required,
If one or two people are required to handle the power receiving capacity, i.e., the current capacity, it is necessary to wind a conductor wire with a large diameter around a very large iron core, and the shape of the choke coil becomes very large.

SUMMARY OF THE INVENTION The present invention uses a transformer to sense the signal current and provide no inductance to the transmitted signal.

Effect of the Invention With the above-described configuration, the present invention can improve the drawback that the shape of the power receiving device using the choke coil becomes sharp and the cost increases.

Example FIG. 1 shows an embodiment of the power receiving device of the present invention.

1 is a power receiving device, which mainly includes a transformer 4 and a current control section 3.
It is made up of. One end of the primary winding 4a of the transformer 4 is connected to one end of the home path 2 via the terminal 7, and the other end is connected to one end of the secondary winding 4b of the transformer 4 and to the emitter of the transistor 3&. has been done. A capacitor 5 and a resistor 6 are connected in series to transmit a signal from the other end of the secondary winding 4b of the transformer 4 to the base of the transistor 3&. 9 is a capacitor, and the positive terminal of capacitor 9 is transistor 3! The transistor 3a is connected to the collector of
Connected to the pace of. The negative pole of the capacitor 9 is connected to the other side of the home path 2 via the terminal 8.

10 is a constant voltage circuit that uses a resistor 11, a Zener diode 12, and a capacitor 13 to keep the voltage taken out by the power receiving device 1 constant. The output of the constant voltage circuit supplies power to a powered circuit 14 such as a communication terminal.

Next, the operation will be explained. FIG. 2 is an explanatory diagram of the operation of the embodiment shown in FIG. In FIG. 2, when a bipolar signal such as (m) is superimposed on the home path 2, the signal current tends to flow into the power receiving device 1 side through the terminal 7 in the case of a positive polarity pulse.

When a signal current of a positive polarity pulse of bipolar sign flows through the primary winding 4a of the transformer 4 in the direction of arrow 15, a current due to electrical induction as shown by arrow 16 flows through the secondary winding 4b. Arrow 1
In order to reduce the pace current of transistor 3, the induced current of transistor 3 is
The collector-emitter voltage V(1+1) of & increases.

Therefore, the signal current of the bipolar positive pulse that was about to flow into the primary winding 4& of the transformer 4 is repelled.

Next, when the Ibora code is a negative polarity pulse, similarly, when the signal current flows through the primary winding 4 of the transformer 4 in the direction opposite to the arrow 16, it flows through the secondary winding 4b in the opposite direction of the arrow 16 due to magnetic induction. Current flows. This induced current is caused by the transistor 3
In order to increase the base current of transistor 2L, the collector-emitter voltage vex of transistor 3IL decreases, as shown at 2 in FIG. 2(B). Therefore, the negative pulse signal current that was about to flow out of the primary winding 42L of the transformer 4 is pulled back.

As described above, neither the signal current of the positive pulse nor the signal current of the negative pulse flows through the primary winding 4a of the transformer 4, and the impedance for the bipolar code of this power receiving device as seen from the home bus 2 is close to infinity. Therefore, the influence on the waveform of the bipolar code on the home bus 2 is reduced.

As described above, the inductance of the transformer required for this power receiving circuit does not need to be as large as 500 mH as in the conventional example, and even the magnetic coupling between the primary winding and the secondary winding is sufficient. If so, 1 mH or less is sufficient.

Therefore, according to the present invention, the number of windings of the transformer is very small, and the shape is very small, so that power can be received without affecting the home bus.

[Brief explanation of drawings]

Fig. 1 is a configuration diagram of a home bus system using a power receiving device for a home bus system according to an embodiment of the present invention, Fig. 2 is an operation waveform diagram of the same device, and Fig. 3 is a home bus system diagram using a conventional power receiving device. A system configuration diagram, FIG. 4 is an equivalent circuit diagram for waveform analysis by a conventional power receiving device, FIG. 6 is an explanatory diagram of bipolar code, and FIG. 6 is an explanatory diagram of waveform distortion. 1... Power receiving device, 2... Home bus,
3...Current control unit, 4...Transformer,
5,9.13・・・Con7F y,su,3&,6
．． 11... Resistor, end, 8... Terminal, 1o... Constant voltage circuit, 12... Zener diode, 14... Power supplied circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Diagram (A) Terminal 7 Peep L Diagram 4 JZ. / : N6 figure

Claims (1)

[Claims] In a home bus system in which DC voltage is superimposed on the home bus and power is supplied from the home bus to terminals connected to the home bus, a transformer having multiple windings is connected in series with the primary winding of the transformer, and is connected to the load. 1. A power receiving device for a home bus system, comprising: a current control element that controls a supplied DC current, and controls a current flowing through the current control section based on an output signal of a secondary winding of the transformer.