CN108594082B - Power-down signal transmission circuit and method for commercial power - Google Patents
Power-down signal transmission circuit and method for commercial power Download PDFInfo
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- CN108594082B CN108594082B CN201810689486.2A CN201810689486A CN108594082B CN 108594082 B CN108594082 B CN 108594082B CN 201810689486 A CN201810689486 A CN 201810689486A CN 108594082 B CN108594082 B CN 108594082B
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Abstract
The invention provides a circuit and a method for detecting a power-down signal of a commercial power, wherein the circuit comprises the following components: a front stage power supply circuit and a rear stage driving circuit; the pre-stage power supply circuit is provided with a power failure detection circuit and an output regulating circuit; the power-down detection circuit is connected with the mains supply and is used for transmitting a power-down signal to the output regulation circuit after detecting that the mains supply is powered down; the output regulating circuit is used for changing the voltage or current output by the backward driving circuit based on the power-down signal transmitted by the power-down detecting circuit; the rear-stage driving circuit is provided with an input detection circuit, and the input end of the input detection circuit is connected with the output end of the output regulating circuit in the front-stage power supply circuit and is used for obtaining a mains supply power-down signal according to the change of the voltage or the current output by the output regulating circuit. The detection circuit provided by the invention can directly regulate the output power supply of the power supply at the moment of power failure, and the post-stage circuit detects the voltage value and then judges the power failure state, so that the circuit structure is simplified and the interface of the power supply is unified.
Description
Technical Field
The invention relates to the technical field of detection circuits, in particular to a circuit and a method for detecting a power-down signal of a commercial power.
Background
With the continuous development of industrial technology, various electric equipment is increased, and further, the demand for power supply is increased. For systems using ac mains, it is often necessary to react at the instant of mains loss, thereby effectively protecting the load.
At present, a detection module in a commercial power failure detection circuit outputs a signal to a rear stage for driving and controlling through a signal wire, but because product planning sometimes hopes that a front-stage power module and a rear-stage driving and controlling are made into separate physical entities and then are connected, one more signal wire needs to be connected besides a power output wire, and thus, the use of a product can be interfered.
Disclosure of Invention
The invention provides a mains power down signal transmission circuit and a method thereof to overcome or at least partially solve the above problems.
According to one aspect of the present invention, there is provided a power-down signal transmission circuit, characterized by comprising:
a front stage power supply circuit and a rear stage driving circuit;
the pre-stage power supply circuit is provided with a power failure detection circuit and an output regulating circuit; the power-down detection circuit is connected with the mains supply and is used for transmitting a power-down signal to the output regulation circuit after detecting that the mains supply is powered down; the output regulating circuit is used for changing the voltage or current output to the rear-stage driving circuit based on the power-down signal transmitted by the power-down detecting circuit;
the rear-stage driving circuit is provided with an input detection circuit, and the input end of the input detection circuit is connected with the output end of the output regulating circuit in the front-stage power supply circuit and is used for obtaining a mains supply power-down signal according to the change of the voltage or the current output by the output regulating circuit.
Optionally, the output adjusting circuit includes a first transistor Q1 and a first resistor R1 connected in series with the first transistor Q1; the input detection circuit comprises an operational amplifier U1;
one end of the first resistor R1 is connected with the first transistor Q1, and the other end of the first resistor R1 is connected with the positive input end of the operational amplifier U1; the positive input end of the operational amplifier U1 is also connected with a reference power supply Vref through a second resistor R2; the negative input end of the operational amplifier U1 is grounded through a third resistor R3;
when the mains supply is normal, the first transistor Q1 is cut off, and the voltage of the positive input end of the operational amplifier U1 is equal to the reference power supply Vref;
when the mains supply is powered down, the first transistor Q1 is turned on, and the voltage of the positive input end of the operational amplifier U1 is reduced and smaller than the reference power supply Vref.
Optionally, the first transistor Q1 is a MOS transistor, and one end of the first resistor R1 is connected to the drain of the first transistor Q1;
the source electrode of the first transistor Q1 is grounded, and the gate electrode is connected to the first power supply voltage VCC1 through a fourth resistor R4.
Optionally, the power down detection circuit includes: a second transistor Q2 connected to the mains, and a first optocoupler U2 connected to the second transistor Q2;
the second transistor Q2 is connected with the cathode of the light emitting diode D3 in the primary side of the first optical coupler U2 in the output regulating circuit, and transmits a voltage signal transmitted by the commercial power to the first optical coupler U2; the anode of the light emitting diode D3 in the primary side of the first optical coupler U2 is connected with a second power supply voltage VCC2 through an eighth resistor R8;
an emitter of the secondary side triode Q3 in the first optocoupler U2 is connected with a source electrode of the first transistor Q1, and a collector of the secondary side triode Q3 in the first optocoupler U2 is connected with a grid electrode of the first transistor Q1;
when the mains supply is normal, the second transistor Q2 is conducted, and the first optocoupler U2 is conducted;
when the mains supply is powered down, the second transistor Q2 is cut off, and the first optocoupler U2 is cut off.
Optionally, the second transistor Q2 is a triode;
the collector electrode of the second transistor Q2 is connected with the cathode of the light-emitting diode D3 in the primary side of the first optical coupler U2; and the base electrode of the second transistor Q2 is connected with the mains supply, and the emitter electrode of the second transistor Q2 is grounded.
Optionally, the power down detection circuit further includes: a first diode D1, a second diode D2, a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7;
the positive electrode of the first diode D1 is connected with a live wire L, and the positive electrode of the second transistor D2 is connected with a zero line N; the cathodes of the first transistor D1 and the second transistor D2 are grounded through a fifth resistor R5 and a sixth resistor R6 which are connected in series at the same time; one end of the fifth resistor R5 connected with the sixth resistor R6 is connected with the base electrode of the second transistor Q2 through a seventh resistor.
Optionally, the power down detection circuit further includes: a first capacitor C1;
the first capacitor C1 is connected in parallel with the sixth resistor R6, one end of the first capacitor is connected to the base electrode of the second transistor Q2 through the seventh resistor R7, and the other end of the first capacitor is grounded together with the emitter electrode of the second transistor Q2.
When the mains supply is normal, the first capacitor C1 may store a voltage, and when the ac power output from the mains supply crosses the zero point, the voltage is provided to the second transistor Q2.
Optionally, the input detection circuit further includes: a ninth resistor R9, a second capacitor C2 and a second photo coupler U3;
one end of the ninth resistor R9 is connected with the output end of the operational amplifier U1, the other end of the ninth resistor R9 is connected with a second capacitor C2 in series, and the second capacitor C2 is also connected with the negative input end of the operational amplifier U1;
the operational amplifier U1, the ninth resistor R9, and the second capacitor C2 form a voltage feedback loop, where the voltage feedback loop is configured to obtain a feedback reference through the mains voltage signal detected by the power failure detection circuit, so as to adjust the power output voltage of the rear stage driving circuit.
Optionally, the input detection circuit further includes: a second optocoupler U3, a tenth resistor R10;
the cathode of the light emitting diode D4 in the primary side of the second optical coupler U3 is connected with the output end of the operational amplifier U1, and the anode is connected with a first power supply voltage VCC1 through the tenth resistor R10;
the secondary side of the second optocoupler U3 is connected with a control IC, and the control IC is used for controlling the primary side of the second optocoupler U3 according to the voltage of the positive input end of the operational amplifier U1 so as to adjust the output voltage of a power supply, and the rear-stage driving circuit judges whether the load is normally driven according to the output voltage of the power supply.
Optionally, the input detection circuit further includes a resistor R0, and one end of the resistor R0 is connected to the negative input end of the operational amplifier U1 and the second capacitor C2 at the same time;
when the commercial power is normal, the control IC adjusts the output voltage of the power supply to be (R0+R3) Vref/R3, and the later stage driving circuit drives the load normally;
when the mains supply is powered down, the control IC adjusts the output voltage of the power supply to be
(R0+R3) R1 Vref/(R1+R2) R3, the latter stage driving circuit stops driving the load.
According to another aspect of the present invention, there is also provided a method for transmitting a power-down signal of a utility power, including:
the power-down detection circuit detects a power-down signal of the mains supply, and after the power-down detection signal detects the power-down of the mains supply, the power-down signal is transmitted to the output regulation circuit in the pre-stage power circuit, and the output regulation circuit changes the voltage or current output by the backward driving circuit;
and an input detection circuit in the rear-stage driving circuit obtains a mains supply power-down signal according to the change of the voltage or the current output by the output regulating circuit.
Optionally, the output adjusting circuit changes a voltage or a current output to the post-stage driving circuit, including:
if the first transistor Q1 in the output adjusting circuit is cut off, the first resistor R1 connected with the positive input end of the operational amplifier U1 in the input detecting circuit does not work;
if the first transistor Q1 in the output adjusting circuit is turned on, the first resistor R1 connected to the positive input terminal of the operational amplifier U1 operates.
Optionally, the positive input end of the operational amplifier U1 is also connected with a reference power supply Vref through a second resistor R2; the negative input end of the operational amplifier U1 is grounded through a third resistor R3;
if the first resistor R1 connected with the positive input end of the operational amplifier U1 in the input detection circuit does not work, judging that the commercial power is normal, wherein the voltage of the positive input end of the operational amplifier U1 is Vref;
if the first resistor R1 connected to the positive input end of the operational amplifier U1 works, the voltage at the positive input end of the operational amplifier U1 is R1 Vref/(r1+r2), and it is determined that the commercial power is lost.
Optionally, the detecting, by a power-down detection circuit provided in the pre-stage power supply circuit, a power-down signal of the mains supply includes:
the power failure detection circuit detects the voltages of a zero line and a live line of alternating current through the second transistor Q2, judges that the commercial power is normal when the second transistor Q2 in the power failure detection circuit is conducted, and couples a signal of the normal commercial power to a secondary side through the first optical coupler U2 to transmit the signal to the output regulation circuit;
when the second transistor Q2 in the power-down detection circuit is turned off, the power-down of the commercial power is judged, and a signal of the power-down of the commercial power is coupled to the secondary side through the first optical coupler U2 and is transmitted to the output regulating circuit.
Optionally, the power failure detection circuit further stores a voltage through the first capacitor C1, and provides the voltage to the second transistor Q2 when the alternating current output by the mains power crosses the zero point.
Optionally, after the input detection circuit in the later stage driving circuit obtains the power-down signal according to the change of the voltage or the current output by the output adjusting circuit, the input detection circuit further includes:
and changing the output voltage of the power supply based on the mains supply power-down signal, and judging whether the load is normally driven by the rear-stage driving circuit according to the output voltage of the power supply.
Optionally, the changing the power supply output voltage based on the mains power down signal includes:
the input detection circuit comprises a voltage feedback loop consisting of an operational amplifier U1, a ninth resistor R9 around the operational amplifier U and a second capacitor C2; the second capacitor C2 is connected with the power supply voltage output end through a resistor R0;
and changing the feedback reference of the voltage feedback loop through the detected normal or power-down signal of the mains supply, so as to change the output voltage of the power supply.
Optionally, the changing the feedback reference of the voltage feedback loop by the detected normal or power down signal of the mains supply, thereby changing the output voltage of the power supply, includes:
when the voltage of the positive input end of the operational amplifier U1 is Vref, the control IC connected with the secondary side of the second optical coupler U3 adjusts the output voltage of the power supply to be (R0+R3) Vref/R3, and the rear-stage driving circuit normally drives a load;
when the voltage of the positive input end of the operational amplifier U1 is R1 Vref/(R1+R2), the power output voltage is regulated by the control IC connected with the secondary side of the second optocoupler U3 as follows:
(R0+R3) R1 Vref/(R1+R2) R3, the latter stage driving circuit stops driving the load.
The embodiment of the invention provides a power-down signal transmission circuit and a power-down signal transmission method for commercial power, wherein a power-down detection circuit is arranged in a front-stage power supply circuit to detect the power-down signal of the commercial power in real time, once the power-down of the commercial power is detected, an output regulating circuit rapidly changes the voltage or current output to a rear-stage driving circuit, and the power-down signal of the commercial power is obtained when the change of the voltage or current is detected by an input detection circuit arranged in the rear-stage driving circuit, so that corresponding response is made. The mains power down signal transmission circuit provided by the embodiment of the invention eliminates the traditional mode of transmitting the mains power down signal by using the single signal wire, directly transmits the mains power down signal through the main output of the power supply, not only can simplify the circuit structure, but also can unify the connection of the power supply, and reduces or avoids signal interference caused by the single signal wire.
The foregoing description is only an overview of the present invention, and is intended to be implemented in accordance with the teachings of the present invention in order that the same may be more clearly understood and to make the same and other objects, features and advantages of the present invention more readily apparent.
The above, as well as additional objectives, advantages, and features of the present invention will become apparent to those skilled in the art from the following detailed description of a specific embodiment of the present invention when read in conjunction with the accompanying drawings.
Drawings
Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Also, like reference numerals are used to designate like parts throughout the figures. In the drawings:
FIG. 1 is a schematic diagram of a conventional power-down signal transmission circuit;
fig. 2 is a schematic diagram of a power-down signal transmission circuit according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a power-down signal transmission circuit according to a preferred embodiment of the present invention;
fig. 4 is a schematic flow chart of a method for transmitting a power-down signal of a commercial power according to an embodiment of the invention.
Detailed Description
Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.
At present, in most electronic products, as shown in fig. 1, a power output end is provided with a rear-stage control and driving module, and as the module needs to rapidly store data at the moment of power failure of commercial power alternating current AC so as to memorize the current working state when the electronic product is started next time, a commercial power failure detection unit is integrated on a front-stage power module or a corresponding power failure detection unit is externally added. Besides the connecting wire originally used for voltage output, when the mains supply is powered down, the power-down detection circuit outputs a signal to the rear-stage driving and control module through the signal wire, and the rear-stage driving and control module rapidly reacts to the power failure of the mains supply. In the above scheme, the power-down signal is transmitted through a separate signal line, which may cause interference to the use of the product.
Fig. 2 is a schematic diagram of a power-down detection circuit according to an embodiment of the present invention, and as shown in fig. 2, the power-down detection circuit provided in the embodiment of the present invention may include: a front-stage power supply circuit 10 and a rear-stage drive circuit 20, the front-stage power supply circuit 10 being provided with a power-down detection circuit 11 and an output adjustment circuit 12; the power-down detection circuit 11 is connected with alternating current AC of the mains supply, and is used for transmitting a signal to the output adjustment circuit 12 after detecting that the mains supply is powered down, and the output adjustment circuit 12 is used for changing the voltage or current output by the rear-stage driving circuit 20 based on the power-down signal transmitted by the power-down detection circuit 11;
the rear driving circuit 20 is disposed between the output end of the front power circuit 10 and the load, and is provided with an input detection circuit 21, wherein the input end of the input detection circuit 21 is connected with the output end of the output adjusting circuit 12 in the front power circuit 10, and is used for obtaining a mains power failure signal according to the change of the voltage or the current output by the output adjusting circuit 12.
According to the power-down detection circuit for the mains supply provided by the embodiment of the invention, the power-down detection circuit 11 is arranged in the front-stage power supply circuit 10 to detect the power-down of the mains supply in real time, once the power-down of the mains supply is detected, the output regulation circuit 12 rapidly changes the voltage or current output to the rear-stage driving circuit 20, and the power-down signal of the mains supply is obtained when the change of the voltage or current is detected by the self-contained input detection circuit 21 in the rear-stage driving circuit, so that corresponding response is made. Based on the commercial power down signal detection circuit provided by the embodiment, the output power supply of the power supply can be directly regulated at the power down moment, the post-stage circuit detects the voltage value and then judges the power down state, so that a signal line for transmitting the power down signal between the pre-stage power supply and the post-stage drive is omitted, the commercial power down signal can be effectively acquired by the post-stage circuit while the circuit setting is simplified, and further the reaction is rapidly made.
At present, most products are composed of a front-stage constant-voltage power supply combined with a rear-stage dimming module (comprising an MCU), the MCU needs to store the current state at the moment of power failure, and the next power-on continues the state. Since the front stage and the rear stage are physically integrated, there may be one signal line inside to transmit the power down signal. However, the separate signal line may interfere with use. Based on the scheme provided by the embodiment of the invention, the front-stage power supply can be used as a common constant-voltage power supply, and can be used as the front stage of a dimming system when applied to a dimming product, so that the application range is wider.
Fig. 3 shows a schematic diagram of a power-down detection circuit according to a preferred embodiment of the present invention, and as shown in fig. 3, the output adjustment circuit 12 may include a first transistor Q1 and a first resistor R1 connected in series with the first transistor Q1; the input detection circuit 21 may include an operational amplifier (op amp) U1; one end of the first resistor R1 is connected with the first transistor Q1, and the other end of the first resistor R1 is connected with the positive input end of the operational amplifier U1; the positive input end of the operational amplifier U1 is also connected with a reference power supply Vref through a second resistor R2; the negative input of the operational amplifier U1 is grounded through a third resistor R3.
When the mains supply is normal, the first transistor Q1 is cut off, and the voltage of the positive input end of the operational amplifier U1 is equal to the reference power supply Vref; when the mains supply is powered down, the first transistor Q1 is turned on, and the voltage of the positive input end of the operational amplifier U1 is reduced and is smaller than the reference power supply Vref. In this embodiment, the power-down signal of the mains supply is obtained mainly by detecting the magnitude of the input voltage of the operational amplifier U1, that is, comparing the input voltage with the voltage input under normal conditions, and if the voltage is found to change, determining that the mains supply is powered down. In addition to the description of the embodiment, the output voltage of the front stage power supply circuit may be determined by a comparator or other manners, which is not limited by the present invention. Preferably, the first transistor Q1 may be a MOS transistor, and one end of the first resistor R1 is connected to the drain of the first transistor Q1; the source of the first transistor Q1 is grounded, and the gate is connected to the first power supply voltage VCC1 through the fourth resistor R4.
With continued reference to fig. 3, the power down detection circuit 11 may include: a second transistor Q2 connected to the mains and a first optocoupler U2 connected to the second transistor Q2. The second transistor Q2 is connected to the cathode of the light emitting diode D3 in the primary side of the first optocoupler U2 in the output adjusting circuit 12, and transmits the voltage signal transmitted by the commercial power to the first optocoupler U2; the anode of the light emitting diode D3 in the primary side of the first optocoupler U2 is connected to the second power supply voltage VCC2 through an eighth resistor R8. An emitter of the secondary side triode Q3 in the first optical coupler U2 is connected with a source electrode of the first transistor Q1, and a collector of the secondary side triode Q3 in the first optical coupler U2 is connected with a grid electrode of the first transistor Q1; when the mains supply is normal, the second transistor Q2 is conducted, and the first optocoupler U2 is conducted; when the mains supply is powered down, the second transistor Q2 is turned off and the first optocoupler U2 is turned off. Optionally, the second transistor Q2 is a triode; the collector electrode of the second transistor Q2 is connected with the cathode of the light-emitting diode D3 in the primary side of the first optical coupler U2; the base electrode of the second transistor Q2 is connected with the mains supply and the emitter electrode is grounded. The power failure detection circuit 12 mainly detects whether the input mains supply (i.e. alternating current AC) is normal, under normal conditions, Q2 will be turned on, and then U2 is turned on, and Q1 does not work; when the mains supply is powered down, Q2 is cut off, and Q1 is switched on for working, so that the voltage of the positive input end of the operational amplifier U1 is reduced and is smaller than the reference voltage Vref.
The power-down detection circuit 11 may further include: a first diode D1, a second diode D2, a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7; the positive electrode of the first diode D1 is connected with the live wire L, and the positive electrode of the second transistor D2 is connected with the zero line N; the cathodes of the first transistor D1 and the second transistor D2 are grounded through a fifth resistor R5 and a sixth resistor R6 which are connected in series at the same time; one end of the fifth resistor R5 connected with the sixth resistor R6 is connected with the base electrode of the second transistor Q2 through a seventh resistor. The fifth resistor R5, the sixth resistor R6, and the seventh resistor R7 can function as voltage dividing in the circuit shown in fig. 3. In practical application, the resistor devices with different numbers and different sizes can be set according to different requirements, and the invention is not limited.
Optionally, the power down detection circuit may further include: a first capacitor C1; the first capacitor C1 is connected in parallel with the sixth resistor R6, and one end is connected to the base of the second transistor Q2 through the seventh resistor R7, and the other end is grounded simultaneously with the emitter of the second transistor Q2. The first capacitor C1 may store a voltage when the mains supply is normal, and provide the voltage to the second transistor Q2 when the ac power output from the mains supply crosses the zero point. Since the alternating current normally has a zero crossing, the second transistor Q2 may be turned on and may be interrupted, but due to the presence of the first capacitor C1, the voltage stored by it can avoid the moment of zero crossing of the alternating current, but if the mains is powered down, the second transistor Q2 is delayed for a short time and then turned off.
The input detection circuit 21 may further include: a ninth resistor R9, a second capacitor C2 and a second photo coupler U3; one end of the ninth resistor R9 is connected with the output end of the operational amplifier U1, the other end of the ninth resistor R9 is connected with the second capacitor C2 in series, and the second capacitor C2 is also connected with the negative input end of the operational amplifier U1; the operational amplifier U1, the ninth resistor R9, and the second capacitor C2 form a voltage feedback loop, and the voltage feedback loop is used for obtaining a feedback reference through the mains voltage signal detected by the power-down detection circuit 12, so as to adjust the power output voltage of the post-stage driving circuit 20.
Further, the input detection circuit 21 may further include: a second optocoupler U3, a tenth resistor R10; the cathode of a light emitting diode D4 in the primary side of the second optical coupler U3 is connected with the output end of the operational amplifier U1, and the anode is connected with a first power supply voltage VCC1 through a tenth resistor R10; the triode Q4 in the secondary side of the second optocoupler U3 is connected with a control IC, the control IC can control the primary side of the second optocoupler U3 according to the voltage of the positive input end of the operational amplifier U1 so as to adjust the output voltage of the power supply, and a rear-stage driving circuit judges whether the load is normally driven according to the output voltage of the power supply.
With continued reference to fig. 3, the input detection circuit 21 further includes a resistor R0, and one end of the resistor R0 is connected to the negative input terminal of the operational amplifier U1 and the second capacitor C2 at the same time. When the commercial power is normal, the control IC can adjust the output voltage of the power supply to be (R0+R3) Vref/R3, and at the moment, the later stage driving circuit drives the load normally; when the commercial power is lost, the control IC can adjust the power output voltage to (R0+R3) R1 Vref/(R1+R2) R3, and at the moment, the later stage driving circuit stops driving the load, namely, stops outputting current to the load. Fig. 3 also shows a partial circuit of the power supply output, a third capacitor C3, a fourth capacitor C4, a third diode D5, a transformer T, etc. connected in parallel with the output terminal V0. When the mains supply is powered down, the pre-stage power supply circuit 10 is equivalent to no-load output, the energy stored in the third capacitor C3 and the fourth capacitor C4 in the power supply can ensure that output voltage exists for a long time, and the post-stage driving circuit 20 also has enough time to store the current state and report the state.
In the mains supply power-down signal transmission circuit provided by the preferred embodiment of the invention, whether the mains supply is normal is detected firstly, and then the mains supply output signal is fed back to the output regulating circuit through the optical coupler, and when the output regulating circuit judges that the mains supply is powered down, the voltage feedback reference of the operational amplifier can be changed rapidly, and the output voltage of the power supply is changed by combining with the control IC. According to the embodiment of the invention, the output power supply of the power supply is regulated at the moment of power failure, the post-stage circuit detects the voltage value and then judges the power failure state, so that an independent signal wire can be omitted, the mains power failure signal can be directly transmitted through the main output of the power supply, the circuit structure can be simplified, and the interface of the power supply can be unified. The above embodiments mainly describe that after the power-down signal of the mains supply is detected, the voltage output by the output circuit of the front-stage power supply is adjusted, and based on a similar method, the current output by the output circuit of the front-stage power supply can also be adjusted, and the change of the input current is detected by a comparator or other devices to obtain the power-down signal of the mains supply, so that the output to the load is controlled by the driving circuit of the rear stage.
Based on the same inventive concept, the embodiment of the present invention further provides a method for transmitting a power-down signal of a commercial power, as shown in fig. 4, where the method for transmitting the power-down signal of the commercial power provided in the embodiment may include:
step S402, a power-down detection circuit arranged in a front-stage power supply circuit detects a power-down signal of the mains supply, the power-down detection circuit transmits the power-down signal to an output regulating circuit in the front-stage power supply circuit after detecting the power-down of the mains supply, and the output regulating circuit changes the voltage or the current output by a rear-stage driving circuit;
in step S404, the input detection circuit in the later stage driving circuit obtains a power-down signal according to the change of the voltage or current output by the output adjustment circuit.
According to the power-down signal transmission method for the commercial power, provided by the embodiment of the invention, after the power-down adding detection circuit in the current stage power circuit detects the power-down of the commercial power, the output regulation circuit can rapidly change the voltage or current output by the backward stage driving circuit, so that the power-down signal of the commercial power is transmitted by utilizing the change of the output voltage or current of the previous stage power circuit, the mode of transmitting the power-down signal through a single signal wire is improved, the power-down signal of the commercial power is directly transmitted through the main output of the power supply, the circuit structure is simplified, and the interface of the power supply can be unified.
Wherein, mentioned in step S402, the voltage or current outputted from the post-stage driving circuit may be changed by the output adjusting circuit, preferably, it may include:
if the first transistor Q1 in the output regulating circuit is cut off, the first resistor R1 connected with the positive input end of the operational amplifier U1 in the input detecting circuit does not work; if the first transistor Q1 in the output adjusting circuit is turned on, the first resistor R1 connected to the positive input terminal of the operational amplifier U1 operates. That is, the first transistor Q1 is turned on or not to transmit the normal or power-off signal of the mains supply, so as to control the working state of the first resistor R1 connected to the positive input terminal of the operational amplifier U1, so as to change the input voltage of the positive input terminal of the operational amplifier U1.
Preferably, the positive input end of the operational amplifier U1 is also connected with a reference power supply Vref through a second resistor R2; the negative input end of the operational amplifier U1 is grounded through a third resistor R3;
if the first resistor R1 connected with the positive input end of the operational amplifier U1 in the input detection circuit does not work, judging that the commercial power is normal, wherein the voltage of the positive input end of the operational amplifier U1 is Vref; if the first resistor R1 connected to the positive input end of the operational amplifier U1 works, the voltage at the positive input end of the operational amplifier U1 is R1 Vref/(r1+r2), and it is determined that the commercial power is lost.
In the step S402, the power-down signal of the utility power may also be detected by a power-down detection circuit provided in the pre-stage power supply circuit, which may specifically include:
the power failure detection circuit detects the voltages of a zero line and a live line of alternating current through the second transistor Q2, judges that the commercial power is normal when the second transistor Q2 in the power failure detection circuit is conducted, and couples a signal of the normal commercial power to the secondary side through the first optical coupler U2 to transmit the signal to the output regulation circuit;
when the second transistor Q2 in the power-down detection circuit is turned off, the power-down of the commercial power is judged, and a signal of the power-down of the commercial power is coupled to the secondary side through the first optical coupler U2 and is transmitted to the output regulating circuit.
Since the second transistor Q2 may be turned on and off due to a zero crossing of the ac power, in a preferred embodiment of the present invention, the power-down detection circuit may store a voltage through the first capacitor C1 provided therein to supply the voltage to the second transistor Q2 when the ac power outputted from the mains crosses the zero crossing.
Preferably, the input detection circuit comprises a voltage feedback loop consisting of an operational amplifier U1, a ninth resistor R9 around the operational amplifier U, and a second capacitor C2; the second capacitor C2 is connected with the power supply voltage output end through a resistor R0; as mentioned above, the power output voltage may also be changed based on the mains power down signal, at which time the feedback reference of the voltage feedback loop may be changed by the detected mains power down signal or normal, thereby changing the power output voltage. Further, when the voltage of the positive input end of the operational amplifier U1 is Vref, the control IC connected with the triode Q4 in the secondary side of the second optocoupler U3 adjusts the power supply output voltage to be (R0+R3) Vref/R3, and the later stage driving circuit normally drives a load; when the voltage of the positive input end of the operational amplifier U1 is R1 Vref/(R1+R2), the power output voltage is adjusted by a control IC connected with a triode Q4 in the secondary side of the second optocoupler U3, and the power output voltage is as follows: (R0+R3) R1 Vref/(R1+R2) R3, the latter stage driving circuit stops driving the load.
In the embodiment of the invention, after the input detection circuit in the later stage driving circuit obtains the power-down signal according to the change of the voltage or the current output by the output regulating circuit, the output voltage of the power supply can be changed based on the power-down signal, and the later stage driving circuit judges whether the load is normally driven according to the output voltage of the power supply. If the mains supply is powered down, the output of current to the load is stopped quickly.
According to the mains supply power-down signal transmission method provided by the embodiment of the invention, a traditional mode of transmitting the mains supply power-down signal by using an independent signal wire is eliminated, and the mains supply power-down signal is directly transmitted through the main output of the power supply, so that the circuit structure can be simplified, the connection of the power supply can be unified, and the signal interference caused by the independent signal wire can be reduced or avoided.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present invention, and not for limiting the same; although the invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all technical features thereof can be replaced by others within the spirit and principle of the present invention; such modifications and substitutions do not depart from the scope of the invention.
Claims (15)
1. The utility power down signal transmission circuit is characterized by comprising:
a front stage power supply circuit and a rear stage driving circuit;
the pre-stage power supply circuit is provided with a power failure detection circuit and an output regulating circuit; the power-down detection circuit is connected with the mains supply and is used for transmitting a power-down signal to the output regulation circuit after detecting that the mains supply is powered down;
the output regulating circuit is used for changing the voltage or current output to the rear-stage driving circuit based on the power-down signal transmitted by the power-down detecting circuit;
the rear-stage driving circuit is provided with an input detection circuit, the input end of the input detection circuit is connected with the output end of the output regulating circuit in the front-stage power supply circuit, and the input detection circuit is used for obtaining a mains supply power failure signal according to the change of the voltage or the current output by the output regulating circuit;
the output regulating circuit comprises a first transistor Q1 and a first resistor R1 connected with the first transistor Q1 in series; the input detection circuit comprises an operational amplifier U1;
one end of the first resistor R1 is connected with the first transistor Q1, and the other end of the first resistor R1 is connected with the positive input end of the operational amplifier U1; the positive input end of the operational amplifier U1 is also connected with a reference power supply Vref through a second resistor R2; the negative input end of the operational amplifier U1 is grounded through a third resistor R3;
when the mains supply is normal, the first transistor Q1 is cut off, and the voltage of the positive input end of the operational amplifier U1 is equal to the reference power supply Vref;
when the mains supply is powered down, the first transistor Q1 is turned on, and the voltage of the positive input end of the operational amplifier U1 is reduced and smaller than the reference power supply Vref.
2. The power-down signal transmission circuit according to claim 1, wherein the first transistor Q1 is a MOS transistor, and one end of the first resistor R1 is connected to the drain of the first transistor Q1;
the source electrode of the first transistor Q1 is grounded, and the gate electrode is connected to the first power supply voltage VCC1 through a fourth resistor R4.
3. The power down signal transmission circuit of claim 2, wherein the power down detection circuit comprises: a second transistor Q2 connected to the mains, and a first optocoupler U2 connected to the second transistor Q2;
the second transistor Q2 is connected with the cathode of the light emitting diode D3 in the primary side of the first optical coupler U2 in the output regulating circuit, and transmits a voltage signal transmitted by the commercial power to the first optical coupler U2; the anode of the light emitting diode D3 in the primary side of the first optical coupler U2 is connected with a second power supply voltage VCC2 through an eighth resistor R8;
an emitter of the secondary side triode Q3 in the first optocoupler U2 is connected with a source electrode of the first transistor Q1, and a collector of the secondary side triode Q3 in the first optocoupler U2 is connected with a grid electrode of the first transistor Q1;
when the mains supply is normal, the second transistor Q2 is conducted, and the first optocoupler U2 is conducted;
when the mains supply is powered down, the second transistor Q2 is cut off, and the first optocoupler U2 is cut off.
4. A mains power down signal transmission circuit according to claim 3, wherein the second transistor Q2 is a transistor;
the collector electrode of the second transistor Q2 is connected with the cathode of the light-emitting diode D3 in the primary side of the first optical coupler U2; and the base electrode of the second transistor Q2 is connected with the mains supply, and the emitter electrode of the second transistor Q2 is grounded.
5. The power down signal transmission circuit of claim 4, wherein the power down detection circuit further comprises: a first diode D1, a second diode D2, a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7;
the positive electrode of the first diode D1 is connected with a live wire L, and the positive electrode of the second transistor D2 is connected with a zero line N; the cathodes of the first transistor D1 and the second transistor D2 are grounded through a fifth resistor R5 and a sixth resistor R6 which are connected in series at the same time; one end of the fifth resistor R5 connected with the sixth resistor R6 is connected with the base electrode of the second transistor Q2 through a seventh resistor.
6. The power down signal transmission circuit of claim 5, wherein the power down detection circuit further comprises: a first capacitor C1;
the first capacitor C1 is connected with the sixth resistor R6 in parallel, one end of the first capacitor C is connected with the base electrode of the second transistor Q2 through the seventh resistor R7, and the other end of the first capacitor C is grounded with the emitter electrode of the second transistor Q2 at the same time;
when the mains supply is normal, the first capacitor C1 may store a voltage, and when the ac power output from the mains supply crosses the zero point, the voltage is provided to the second transistor Q2.
7. The power-down signal transmission circuit according to any one of claims 1 to 5, wherein the input detection circuit further comprises: a ninth resistor R9, a second capacitor C2 and a second photo coupler U3;
one end of the ninth resistor R9 is connected with the output end of the operational amplifier U1, the other end of the ninth resistor R9 is connected with a second capacitor C2 in series, and the second capacitor C2 is also connected with the negative input end of the operational amplifier U1;
the operational amplifier U1, the ninth resistor R9, and the second capacitor C2 form a voltage feedback loop, where the voltage feedback loop is configured to obtain a feedback reference through the mains voltage signal detected by the power failure detection circuit, so as to adjust the power output voltage of the rear stage driving circuit.
8. The power-down signal transmission circuit of claim 7, wherein the input detection circuit further comprises: a second optocoupler U3, a tenth resistor R10;
the cathode of the light emitting diode D4 in the primary side of the second optical coupler U3 is connected with the output end of the operational amplifier U1, and the anode is connected with a first power supply voltage VCC1 through the tenth resistor R10;
the secondary side of the second optocoupler U3 is connected with a control IC, and the control IC is used for controlling the primary side of the second optocoupler U3 according to the voltage of the positive input end of the operational amplifier U1 so as to adjust the output voltage of a power supply, and the rear-stage driving circuit judges whether the load is normally driven according to the output voltage of the power supply.
9. The power-down signal transmission circuit according to claim 8, wherein the input detection circuit further comprises a resistor R0, and one end of the resistor R0 is simultaneously connected to the negative input end of the operational amplifier U1 and the second capacitor C2;
when the commercial power is normal, the control IC adjusts the output voltage of the power supply to be (R0+R3) Vref/R3, and the later stage driving circuit drives the load normally;
when the mains supply is powered down, the control IC adjusts the output voltage of the power supply to be
(R0+R3) R1 Vref/(R1+R2) R3, the latter stage driving circuit stops driving the load.
10. The utility power down signal transmission method is characterized by comprising the following steps:
the power-down detection circuit detects a power-down signal of the mains supply, and after the power-down detection signal detects the power-down of the mains supply, the power-down signal is transmitted to the output regulation circuit in the pre-stage power circuit, and the output regulation circuit changes the voltage or current output by the backward driving circuit;
an input detection circuit in the rear-stage driving circuit obtains a mains supply power-down signal according to the change of the voltage or the current output by the output regulating circuit;
wherein the output adjusting circuit changes a voltage or a current output to the rear stage driving circuit, comprising: if the first transistor Q1 in the output adjusting circuit is cut off, the first resistor R1 connected with the positive input end of the operational amplifier U1 in the input detecting circuit does not work;
if the first transistor Q1 in the output adjusting circuit is conducted, a first resistor R1 connected with the positive input end of the operational amplifier U1 works;
wherein, the power down detection circuit that sets up in the preceding stage power supply circuit detects the commercial power and falls the electric signal, include:
the power failure detection circuit detects the voltages of a zero line and a live line of alternating current through the second transistor Q2, judges that the commercial power is normal when the second transistor Q2 in the power failure detection circuit is conducted, and couples a signal of the normal commercial power to a secondary side through the first optical coupler U2 to transmit the signal to the output regulation circuit;
when the second transistor Q2 in the power-down detection circuit is turned off, the power-down of the commercial power is judged, and a signal of the power-down of the commercial power is coupled to the secondary side through the first optical coupler U2 and is transmitted to the output regulating circuit.
11. The method according to claim 10, wherein the positive input of the operational amplifier U1 is further connected to a reference power supply Vref through a second resistor R2; the negative input end of the operational amplifier U1 is grounded through a third resistor R3;
if the first resistor R1 connected with the positive input end of the operational amplifier U1 in the input detection circuit does not work, judging that the commercial power is normal, wherein the voltage of the positive input end of the operational amplifier U1 is Vref;
if the first resistor R1 connected to the positive input end of the operational amplifier U1 works, the voltage at the positive input end of the operational amplifier U1 is R1 Vref/(r1+r2), and it is determined that the commercial power is lost.
12. The method of claim 10, wherein the power down detection circuit further stores a voltage through a first capacitor C1, and provides the voltage to the second transistor Q2 at a zero crossing of the ac power output from the mains.
13. The method according to any one of claims 10-12, wherein after the input detection circuit in the subsequent stage driving circuit obtains the mains power down signal according to the change of the voltage or current output by the output adjustment circuit, further comprising:
and changing the output voltage of the power supply based on the mains supply power-down signal, and judging whether the load is normally driven by the rear-stage driving circuit according to the output voltage of the power supply.
14. The method of claim 13, wherein the changing the power supply output voltage based on the mains power down signal comprises:
the input detection circuit comprises a voltage feedback loop consisting of an operational amplifier U1, a ninth resistor R9 around the operational amplifier U and a second capacitor C2; the second capacitor C2 is connected with the power supply voltage output end through a resistor R0;
and changing the feedback reference of the voltage feedback loop through the detected normal or power-down signal of the mains supply, so as to change the output voltage of the power supply.
15. The method of claim 14, wherein said changing the feedback reference of the voltage feedback loop by the detected normal or power down signal, thereby changing the power supply output voltage, comprises:
when the voltage of the positive input end of the operational amplifier U1 is Vref, the control IC connected with the secondary side of the second optical coupler U3 adjusts the output voltage of the power supply to be (R0+R3) Vref/R3, and the rear-stage driving circuit normally drives a load;
when the voltage of the positive input end of the operational amplifier U1 is R1 Vref/(R1+R2), the power output voltage is regulated by the control IC connected with the secondary side of the second optocoupler U3 as follows:
(R0+R3) R1 Vref/(R1+R2) R3, the latter stage driving circuit stops driving the load.
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| CN201810689486.2A CN108594082B (en) | 2018-06-28 | 2018-06-28 | Power-down signal transmission circuit and method for commercial power |
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| CN109526110B (en) * | 2018-12-27 | 2021-01-26 | 重庆绿色科技开发（集团）有限公司 | Intelligent control system of three-primary-color multi-color-temperature LED street lamp for ZigBee networking communication |
| CN109714856B (en) * | 2018-12-27 | 2021-02-02 | 重庆绿色科技开发（集团）有限公司 | Intelligent control system of three-primary-color multi-color-temperature LED street lamp based on environment detection |
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