JP2014068191A - Digital amplitude modulation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent damage to other circuits from leakage output signals from other power amplifiers when one power amplifier is dismounted or mounted during operation.SOLUTION: According to an embodiment, a digital amplitude modulation device power-amplifies a predetermined signal in a plurality of power amplifiers arranged in parallel so as to be controlled on/off in response to a voltage amplitude level of a signal to be modulated, and combines outputs of the respective power amplifiers in a combiner comprising primary windings of transformers connected to the respective power amplifiers and secondary windings of the transformers opposed to the primary windings, to generate an amplitude-modulated wave. The plurality of power amplifiers each include first switching means and second switching means. The first switching means switches between supply and interruption of power. The second switching means switches the primary winding of the transformer for the power amplifier switched between supply and interruption of power to a normally open state or a short circuit state, and switches to supply or interruption of an on/off control signal.

Description

  Embodiments described herein relate generally to a digital amplitude modulation apparatus used in a transmission apparatus for medium wave broadcasting, for example.

  For example, in medium-wave broadcasting, a plurality of power amplifiers arranged in parallel are provided, and an amplified carrier signal is output by controlling on / off of the plurality of power amplifiers according to the voltage amplitude level of the modulated signal. A digital amplitude modulation device that generates AM waves (Amplitude Modulation Waves) by combining the output signals of power amplifiers that are turned on and sends them to a predetermined broadcast service area. It's being used.

  The digital amplitude modulation device requires stable operation for many years, and therefore requires regular maintenance of the power amplifier. This maintenance work is performed by removing the power amplifier from the digital amplitude modulator during the operation of the digital amplitude modulator. If the power amplifier fails, it is necessary to remove the failed power amplifier and replace it with a normal power amplifier.

  However, if the power amplifier is removed from the digital amplitude modulation device or attached when the digital amplitude modulation device is operating, the output signal from the other power amplifier leaks and damages other related circuits. May give.

  For example, in Patent Document 1, during operation of a digital amplitude modulation device, power having a function of realizing an off state by a disable signal for disconnecting and / or replacing one power amplifier of a plurality of power amplifiers The power amplifier includes a switch and a controller for controlling enable and disable, a short-circuit switch and a switch driver for realizing a normal open state and a short-circuit state of the primary winding, and a power amplifier based on a disable signal in the power amplifier A digital amplitude modulation device is proposed, characterized in that it comprises the steps of: realizing an off state of the power amplifier; shorting a primary winding associated with the power amplifier; and disconnecting the power amplifier from the digital amplitude modulation device. .

JP 2001-352259 A

  By the way, in the digital amplitude modulation apparatus proposed in the above-mentioned Patent Document 1, a short time delay (several milliseconds) is realized after the step of using the timer and realizing the off state of the power amplifier. Short the primary winding associated with. As a result, the output signal from the other power amplifier leaks to the primary winding for a short time, which may cause damage to the transformer and other related circuits.

  An object of the present invention is to provide a digital amplitude modulation device capable of preventing damage to other circuits due to leakage of an output signal from another power amplifier even if the power amplifier is removed or attached during operation. There is.

  According to the embodiment, according to the embodiment, the digital amplitude modulation device can amplify a predetermined signal with a plurality of power amplifiers arranged in parallel and capable of being turned on / off according to the voltage amplitude level of the modulated signal. Then, an amplitude modulated wave is generated by synthesizing the output of each power amplifier by a synthesizer composed of a primary winding of the transformer connected to each power amplifier and a secondary winding facing the primary winding of the transformer. In the digital amplitude modulation device, each of the plurality of power amplifiers includes a first switching unit and a second switching unit. The first switching means switches between power supply and cutoff. The second switching means switches the primary winding of the transformer of the power amplifier that is switched between power supply and cutoff by the first switching means to a normal open state or a short circuit state, and ON / OFF control input to the power amplifier Switches between signal supply and cutoff.

1 is a block diagram showing a configuration of a digital amplitude modulation apparatus according to a first embodiment. The circuit block diagram which shows the specific structure of the power amplifier which concerns on 1st Embodiment, and a synthetic | combination part. The characteristic view which shows the output voltage of the power amplifier which concerns on 1st Embodiment. The circuit block diagram which shows the relay circuit which concerns on 1st Embodiment. The circuit block diagram which shows the specific structure of the power amplifier which concerns on 2nd Embodiment, and a synthetic | combination part. The flowchart which shows the power supply voltage interruption | blocking control procedure when removing a power amplifier and its content in 2nd Embodiment. The other circuit block diagram which shows the specific structure of the power amplifier which concerns on 2nd Embodiment, and a synthetic | combination part. The flowchart which shows the power supply voltage interruption | blocking control procedure when attaching a power amplifier in 2nd Embodiment, and the content. The flowchart which shows the power supply voltage interruption | blocking control procedure when removing a power amplifier and its content in 3rd Embodiment. In 3rd Embodiment, the power supply voltage cutoff control procedure when attaching a power amplifier, and the flowchart which shows the content.

  Hereinafter, embodiments will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a block diagram showing the configuration of the digital amplitude modulation apparatus according to the first embodiment.

  A carrier signal as a transmission signal is input to the carrier signal input terminal 101 of the digital amplitude modulation apparatus 100 shown in FIG. The carrier signal input to the carrier signal input terminal 101 is distributed and supplied to n (n is an arbitrary natural number) power amplifiers 1201 to 120n of a power amplifier (PA) 120. Each of the power amplifiers 1201 to 120n becomes ON = driving state and OFF = stopped state according to the control of the control unit 110, and outputs the carrier signal amplified in the ON state.

  The amplified carrier signal is synthesized by the synthesis unit 130, filtered by the filter unit 140, and then output from the output signal terminal 103 as an amplitude-modulated RF band broadcast wave (AM wave). A transmitting antenna (not shown) is connected to the end of the output signal terminal 103, and generally, a matching circuit, a filter, a rejector, a track circuit, and the like are inserted therebetween.

  On the other hand, an audio signal (modulated signal) input to the digital amplitude modulation apparatus 100 is input to the control unit 110. The control unit 110 controls the on / off state of each of the power amplifiers 1201 to 120n according to the phase difference between the on / off control signal and the carrier signal according to the voltage amplitude of the input audio signal.

  FIG. 2 is a circuit configuration diagram illustrating specific configurations of the power amplifiers 1201 to 120n and the combining unit 130. Here, the power amplifier 1202 will be described as a representative.

  The power amplifier 1202 has a class D full bridge configuration including switching elements 13 to 16 made of, for example, MOSFETs, and the power supply voltage Vin is supplied via the switch 121.

  The combining unit 130 includes n transformers (# 1 to #n), the primary winding is connected to the output terminal of the power amplifier 1202, the secondary winding is connected in series, and one end thereof is directly grounded. Alternatively, it is grounded via a coil, a capacitor, a resistor, or a combination thereof, and the other end is used as a combined output end. That is, in the combining unit 130, when the carrier signal amplified by any of the power amplifiers 1201 to 120n is added to the primary winding, it is output to the secondary winding side and combined.

  Furthermore, the power amplifier 1202 includes a control connector 10 that can be detachably attached to the control unit 110, a switch controller 11 for switching control of the switch 121, and a relay that shorts or opens the primary winding of the transformer # 2. A circuit 12 is provided. In the control connector 10, an on / off control signal and / or a carrier signal and a switching current for short-circuiting or opening a primary winding associated with the power amplifier flow. The other power amplifiers 1201, 1203 to 120 n are also provided with a control connector 10, a switch controller 11, and a relay circuit 12, similarly to the power amplifier 1202.

  In the power amplifier 1202, when an on / off control signal or a carrier signal is supplied from the control unit 110 via the control connector 10, the switching elements 13 to 16 are subjected to switching control to generate an RF signal as shown in FIG. 3. Output. That is, in the RF signal S1, the switching element 13 and the switching element 16 are turned on, and the switching element 14 and the switching element 15 are turned off. On the other hand, in the RF signal S2, the switching element 14 and the switching element 15 are turned on, and the switching element 13 and the switching element 16 are turned off.

  As shown in FIG. 4, the relay circuit 12 includes a switch 12a. When the relay current is supplied from the relay power source 123 to the coil 12b, the switch 12a is switched to the terminal 12c side, and is in a normally open state. It is in. When the control connector 10 is removed, the relay current is not supplied from the relay power source 123 to the coil 12b, the switch 12a is switched to the terminal 12d side, and the primary winding of the transformer # 2 is short-circuited.

  Next, the removal or attachment operation of the power amplifier having the above configuration will be described.

  Each of the power amplifiers 1201 to 120n includes a switch controller 11 and a switch 121 that cut off the power supply from the power supply 122, like the power amplifier 1202 shown in FIG. Moreover, the control part 110 and the relay power supply 123 are provided, and each of the power amplifiers 1201-120n is connected via the control connector 10. FIG.

  During the operation of the digital amplitude modulation apparatus, when removing one power amplifier 1202 of the plurality of power amplifiers 1201 to 120n, the power supply power is first shut off using the switch 121, and then the control connector 10 is turned off. By removing, damage to the transformer and other related circuits due to leakage of output signals from the other power amplifiers 1201, 1203 to 120n during operation of the digital amplitude modulation apparatus can be prevented. This is because the current when the power is shut off, that is, when the output is 0, flows to GND because the switching element 14 and the switching element 15 or the switching element 13 and the switching element 16 are in the ON state, and the primary of the transformer # 2 This is because, when the winding is short-circuited, the current does not operate as a transformer, so that the current can be lost and the power amplifier 1202, transformer # 2, and other circuits can be protected.

  Note that when the primary winding of the transformer # 2 is in a short circuit state, no current is generated because the power supply is shut off even when the switching element 13 and the switching element 16 or the switching element 14 and the switching element 15 are turned on. . Therefore, the order of the state switching may be any relationship.

  On the other hand, the reverse operation at the time of installation, that is, by inserting the control connector 10, the on / off control signal is supplied, the primary winding of the transformer # 2 is brought into the normally open state, and then the power is supplied. Thus, one power amplifier 1202 of the plurality of power amplifiers 1201 to 120n can be attached without hindering the operation of the other power amplifiers 1201, 1203 to 120n.

  As described above, in the first embodiment, on / off control of the plurality of power amplifiers 1201 to 120n and switching of the operation state of the relay circuit 12 are performed by the control unit 110 via the control connector 10, so that the operator However, simply attaching and detaching the control connector 10 to and from the power amplifier 1202 enables easy attachment and / or replacement. That is, during the operation of the digital amplitude modulation apparatus, when one power amplifier 1202 is removed, the power supplied to the power amplifier 1202 to be removed is shut off by the switch 121 and then the power supply is shut off. The primary winding of the transformer # 2 related to the power amplifier 1202 is short-circuited by the relay circuit 12 and the on / off control signal is cut off. On the other hand, when attaching, the primary winding of the transformer # 2 related to the power amplifier 1202 is supplied with the normal open state and the on / off control signal by the relay circuit 12, and then the power is supplied. I have to.

  Accordingly, it is possible to prevent damage to the transformer # 2 and other related circuits due to leakage of output signals from the other power amplifiers 1201, 1203 to 120n during operation.

(Second Embodiment)
In the second embodiment, the primary circuit of the transformer is short-circuited by the relay circuit 12 by using the blow of the fuse as a trigger.

  FIG. 5 is a circuit configuration diagram illustrating specific configurations of the power amplifiers 1201 to 120n and the combining unit 130 according to the second embodiment. Here, the power amplifier 1202 will be described as a representative. In FIG. 5, the same parts as those in FIG.

  The power supply voltage Vin from the power supply 22 is supplied to the switching elements 13 to 16 through the fuses 21. Here, for example, during a lightning strike, a large output may be generated from the power amplifiers 1201 to 120n, and the fuse 21 of the power amplifier 1202 may be cut by an overcurrent. In such a case, the supply of the power supply voltage Vin is interrupted, and the outputs of the switching elements 13 to 16 become zero. At this time, the primary winding of the transformer # 2 is short-circuited by the relay circuit 12 in order to avoid generation of current in the primary winding of the transformer # 2.

  Next, the removal and mounting operations of the power amplifiers 1201 to 120n configured as described above will be described with reference to FIGS. 6 and 7, respectively. Here, the removal and attachment operations will be described using the power amplifier 1202 as an example, but the same applies to other power amplifiers.

  FIG. 6 is a flowchart showing a power supply voltage cutoff control procedure and its contents when the power amplifier 1202 is removed.

  First, it is detected whether or not the power amplifier 1202 is operating (step ST6a). If it is operating (Yes in step ST6a), it is constantly monitored whether or not the fuse 21 is cut (step ST6b). ). Here, when the fuse 21 is cut because the overcurrent has occurred in the power amplifier 1202 due to, for example, a lightning strike (Yes in step ST6b), the primary winding of the transformer # 2 is short-circuited by the relay circuit 12. Then, the on / off control signal input to the power amplifier 1202 via the control connector 10 is blocked (step ST6c).

  If the fuse 21 is not cut in step ST6b (No in step ST6b), the primary winding of the transformer # 2 is set in a normally open state by the relay circuit 12, and the processing in steps ST6a and ST6b is performed. Will be executed repeatedly.

  As described above, according to the second embodiment, when the fuse 21 is cut, the primary winding of the transformer is automatically switched to a short circuit state by the relay circuit 12 and separated from other power amplifiers. Therefore, the power amplifier 1202 can be easily removed.

  Next, a power supply voltage supply control procedure when the power amplifier 1202 is attached will be described. The power amplifier 1202 in this procedure is not limited to the configuration described in FIG. 21, a switch 124 is provided. In this power amplifier 1202, the power supply voltage Vin from the power supply 22 is supplied via the switch 124 and the fuse 21. For example, a large voltage is applied to the power amplifiers 1201 to 120 n during a lightning strike, and the fuse of the power amplifier 1202. When the switch 21 is disconnected, the switch 124 is automatically turned off and the power supply voltage Vin is cut off. At this time, the current flowing through the primary winding of the transformer # 2 is absorbed by the ground (GND) when the switching element 13 and the switching element 16 or the switching element 14 and the switching element 15 are turned on. . Thereafter, the current is lost by short-circuiting the primary winding side of the transformer # 2.

  FIG. 8 is a flowchart showing the power supply voltage supply control procedure and its contents when the power amplifier 1202 is attached.

  First, after the power amplifier 1202 is attached, an on / off control signal input to the power amplifier 1202 is supplied via the control connector 10, and the primary winding of the transformer # 2 is brought into a normally open state by the relay circuit 12. (Step ST8a). Thereafter, the conduction state of the fuse 21 is confirmed (step ST8b). When it is confirmed that the fuse 21 is conducting (YES in step ST8b), power is supplied to the power amplifier 1202 (step ST8c). If it cannot be confirmed that the fuse 21 is conducting (NO in step ST8b), an on / off control signal is supplied, and the primary winding of the transformer # 2 is brought into a normally open state by the relay circuit 12 (step ST8a). Repeat the process.

  In this case, since the current flowing to the primary winding side of the transformer # 2 is absorbed by the GND, damage to the transformer # 2 and other circuits can be prevented.

  As described above, according to the second embodiment, the primary winding of the transformer # 2 related to the power amplifier 1202 is normally opened by the relay circuit 12 and the on / off control signal is supplied. Thus, the power amplifier 1202 can be attached without hindering the operation of other power amplifiers in the digital amplitude modulation apparatus.

  In the second embodiment, the switch 124 shown in FIG. 7 may be provided in the power amplifier 1202 shown in FIG. 5 described in the operation at the time of removal. In the second embodiment, the switch controller 11 shown in FIG. 2 described in the first embodiment can be provided.

(Third embodiment)
In the third embodiment, the operation of removing and attaching the power amplifiers 1201 to 120n will be described with reference to FIGS. 9 and 10, respectively, with the control connector 10 being pulled out from the power amplifier and the control unit as a trigger. Here, the power amplifier 1202 shown in FIG. 2 is taken as an example and the removal and attachment operations will be described, but the same applies to other power amplifiers.

  FIG. 9 is a flowchart showing a power supply voltage cutoff control procedure and its contents when the power amplifier 1202 according to the third embodiment is removed.

  During the operation of the digital amplitude modulator (YES in step ST9a), the operator shuts off the power supply to replace the power amplifier 1202 with another normal power amplifier due to a failure, for example, and then the power amplifier 1202 When the control connector 10 is pulled out (YES in step ST9b), the primary winding of the transformer # 2 is short-circuited by the relay circuit 12, and an on / off control signal input to the power amplifier 1202 via the control connector 10 is received. Blocked (step ST9c). If the control connector 10 is not extracted in step ST9b (No in step ST9b), the power amplifier 1202 repeatedly executes the processes in steps ST9a and ST9b.

  As described above, according to the third embodiment, when the control connector 10 is disconnected from the power amplifier 1202, the primary winding of the transformer # 2 related to the power amplifier 1202 whose power supply is cut off is connected to the relay circuit 12. Therefore, for example, the failed power amplifier 1202 can be safely removed and replaced with another power amplifier.

  FIG. 10 is a flowchart showing a power supply voltage supply control procedure and its contents when the power amplifier 1202 according to the third embodiment is attached.

  When the operator replaces the power amplifier 1202 with another normal power amplifier, for example, due to a failure or the like, after the normal power amplifier is installed, first, the on / off input to the power amplifier 1202 via the control connector 10 is performed. An OFF control signal is supplied, and the primary winding of the transformer # 2 is brought into a normally open state by the relay circuit 12 (step ST10a). Thereafter, when it is confirmed that the control connect 10 of the power amplifier 1202 is inserted (YES in step ST10b), power is supplied to the attached power amplifier 1202 (step ST10c).

  As described above, according to the third embodiment, the primary winding of the transformer # 2 related to the power amplifier 1202 is supplied with the normal open state and the on / off control signal by the relay circuit 12, and then the power source Therefore, the power amplifier 1202 can be attached without hindering the operation of other power amplifiers in the digital amplitude modulation apparatus.

(Other embodiments)
In each of the above embodiments, the example in which the relay circuit is used as a means for causing the primary winding of the transformer related to the power amplifier to be in a short circuit state or a normal open state has been described. However, the embodiment is limited to the relay circuit described in each embodiment. Instead, the description has been made using a mechanical relay as a relay circuit, but a semiconductor relay, a hybrid relay, or other circuits that realize switching may be used.

  Furthermore, the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  DESCRIPTION OF SYMBOLS 10 ... Control connector, 11 ... Switch controller, 12 ... Relay circuit, 13-16 ... Switching element, 21 ... Fuse, 22 ... Power supply, 100 ... Digital amplitude modulator, 1201-120n ... Power amplifier, 121 ... Switch, 122 ... Power supply, 123... Power supply for relay, 130... Synthesizer, 140.

Claims (7)

A predetermined signal is power-amplified by a plurality of power amplifiers arranged in parallel and capable of being turned on / off in accordance with the voltage amplitude level of the modulated signal, a primary winding of a transformer connected to each power amplifier, and the transformer In a digital amplitude modulation device that generates an amplitude-modulated wave by synthesizing the output of each power amplifier with a synthesizer composed of a secondary winding facing the primary winding of
Each of the plurality of power amplifiers includes:
First switching means for switching between power supply and cutoff;
The primary winding of the transformer of the power amplifier that is switched between power supply and cutoff by the first switching means is switched to a normal open state or a short circuit state, and an on / off control signal input to the power amplifier is supplied or A digital amplitude modulation device comprising: a second switching means for switching between cutoffs.   The second switching means includes a fuse, and when the fuse is cut as a trigger, the primary winding of the transformer of the power amplifier to which power is cut off is short-circuited and is turned on / off to be input to the power amplifier. 2. The digital amplitude modulation apparatus according to claim 1, wherein the control signal is cut off.   The second switching means includes a fuse, and triggered by the conduction of the fuse, opens the primary winding of the transformer of the power amplifier to which power is supplied, and is input to the power amplifier. 2. The digital amplitude modulation apparatus according to claim 1, wherein an on / off control signal is supplied.   The digital amplitude modulation apparatus according to claim 1, wherein the second switching means is a detachable control connector.   The second switching means triggers the disconnection of the control connector to short-circuit the primary winding of the transformer of the power amplifier to which power is cut off, and an on / off control signal input to the power amplifier The digital amplitude modulation device according to claim 4, wherein:   The second switching means is an on / off control input to the power amplifier by opening the primary winding of the transformer of the power amplifier to which power is supplied, triggered by the attachment of the control connector. 5. The digital amplitude modulation apparatus according to claim 4, wherein a signal is supplied.   2. The digital amplitude modulation apparatus according to claim 1, wherein the second switching means is a relay circuit.

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