[0022] Example
[0023] The implementation method and circuit for power failure reporting of the power consumption information collection equipment in this embodiment: In this method, the communication module detects the power supply voltage of the meter and the zero-crossing signal of the grid to determine the power failure state. When the power failure state is detected, the carrier chip will Detect multiple grid zero-crossing signals to judge the power-down state. If no zero-crossing signal is detected multiple times, it is considered to be a power-down state, which increases the accuracy of power-down detection; this circuit includes charging circuit, farad capacitor, boost circuit and power-down The detection and control circuit, the charging circuit is connected to the input voltage VDD; the output of the charging circuit is connected to the farad capacitor; the input of the boost circuit is connected to the farad capacitor; the power failure detection and control circuit is connected to the charging circuit respectively Connect to the 4-pin EN of U1 of the boost circuit. The electricity consumption information collection equipment includes single-phase and three-phase electric energy meters, type I collectors, and type II collectors of the State Grid and China Southern Power Grid.
[0024] The charging circuit includes a first control transistor V1, a first current-limiting resistor R40, a second control transistor V2, a pull-up resistor R46, a shunt reference power supply TS1, a filter resistor R65, a filter capacitor C43, a third current-limiting resistor R47, and a A sampling resistor R66, a second sampling resistor R50; the reference voltage circuit TS1 uses a three-terminal adjustable shunt reference power supply TL431 with good thermal stability; one end of the first current limiting resistor R40 is connected to the input voltage VDD and the second control transistor V2 The emitter E is connected to the emitter E of the first control transistor V1; the base B of the first control transistor V1 is connected to the collector C of the second control transistor V2 and one end of the second current limiting resistor R44; The two ends of the pull-up resistor R46 are connected in parallel between the emitter E and the base B of the third control transistor V3; one end of the third current-limiting resistor R47 is connected to the base B of the second control transistor V2; the other end can be connected to the three ends. The cathode K of the adjusted shunt reference power supply TS1 is connected; one end of the filter resistor R65 is connected in series with the filter capacitor C43, and then connected in parallel between the cathode K of the three-terminal adjustable shunt reference power supply TS1 and the reference stage R; the first sampling resistor R66 Connected in parallel between the reference stage R of the three-terminal adjustable shunt reference power supply TS1 and the anode A, one end of the first sampling resistor R66 is connected to one end of the second sampling resistor R50, and the other end of the second R50 is connected to the first control transistor V1 Collector E is connected; the anode A of the three-terminal adjustable shunt reference power supply TS1 is connected to the reference ground GND. The input voltage VDD of the charging circuit can use the 3.3V or 5V power supply of the communication module, and can also use the 12V power supply provided by the electric meter. The output voltage value of the charging circuit can be set by adjusting the values of the first sampling resistor R66 and the second sampling resistor R50. The farad capacitor is composed of a farad capacitor C40; according to power output and power supply time requirements, farad capacitors of different capacities are selected.
[0025] The boost circuit includes a first stabilizing capacitor C41 and a second stabilizing capacitor C21, a power inductor L1, a first freewheeling diode VD6, a second freewheeling diode VD7, a third freewheeling diode VD8, and a boost chip U1, The first current-limiting resistor R45, the first sampling resistor R48, the second sampling resistor R49, and the third sampling resistor C42; the boost chip U1 uses the SX1308 boost chip, or the boost chip with the same boost function; One end of the capacitor C40 is connected to one end of the power inductor L1, and the other end is connected to the reference ground GND. The other end of the power inductor L1 is connected to one end of the second freewheeling diode VD7 and the 1 pin SW of the boost chip U1, respectively. The other end is connected to one end of the second stabilizing capacitor C21, one end of the first freewheeling diode VD6, one end of the short-circuit resistor R43, and the output voltage OUT12V. The other end of the first freewheeling diode VD6 is connected to the input voltage IN12V. The other end of the second regulator capacitor C21 is connected to the reference ground GND; the 2-pin GND of the boost chip U1 is connected to the reference ground GND; the 3-pin FB of the boost chip U1 is connected to the first sampling resistor R48 and the second sampling resistor, respectively One end of R49 is connected, the other end of R48 is connected to the reference ground GND, and the other end of the second sampling resistor R49 is connected to the output voltage OUT12V; the 4-pin EN of the boost chip U1 is connected to one end of the first current limiting resistor R45; The 5-pin IN of the pressure chip U1 is connected to the 6-pin NC, and is connected to the other end of the first current limiting resistor R45, the other end of the short-circuit resistor R43, and one end of the third freewheeling diode VD8, and the third freewheeling diode Two ends of VD8 are connected to the system power supply voltage VDD; the output voltage of the boost circuit is set by adjusting the values of the first sampling resistor R48 and the second sampling resistor R49. The internal logic circuit of the boost chip U1 in the boost circuit is powered by a 12V or 3.3V or 5V power supply of the communication module, so that the lowest input working voltage of the boost circuit can reach 0.8V or less.
[0026] The power-down detection and control circuit includes a third control transistor V3, a fourth control transistor V4, a fifth control transistor V5, a first voltage divider resistor R30, a second voltage divider resistor R31, a third voltage divider resistor R59, and a fourth control transistor V5. The voltage dividing resistor R67, the second current limiting resistor R32, the third current limiting resistor R60 and the clamping diode VD9 are composed; the base B of the third control transistor V3 is connected to one end of the fourth voltage dividing resistor R68 and the third voltage dividing resistor R59 respectively The other end of the fourth voltage divider resistor R68 is connected to the input 12V voltage IN12V, the other end of the third voltage divider resistor R59 is connected to the reference ground GND; the emitter E of the third control transistor V3 is connected to the reference ground; the third control The collector C of the transistor V3 is connected to one end of the third current-limiting resistor R60, and the other end of the third current-limiting resistor R60 is connected to the power supply state DET_V and the collector C of the fifth control transistor V5; the fifth control transistor V5 The emitter E is connected to the reference ground GND; the base of the fifth control transistor V5 is connected to one end of the second voltage dividing resistor R31 and the first voltage dividing resistor R30, and the other end of the first voltage dividing resistor R30 is connected to the reference ground, The other end of the second voltage dividing resistor R31 is connected to the collector C of the fourth control transistor V4; the base B of the fourth control transistor V4 is connected to the anode of the clamp diode VD9 and one end of the second current limiting resistor R32, respectively. The other end of the second current limiting resistor R32 is connected to the input 12V voltage IN12V; the design E of the fourth control transistor V4 is connected to the system power supply voltage VDD and the cathode of the clamp diode VD9; the power failure detection and control circuit (4) The power-down threshold can be set by adjusting the values of the fourth voltage dividing resistor R68 and the third voltage dividing resistor R5; the power-down detection and control circuit (4) notifies the power line carrier chip of the 12V power supply state DET_V.
[0027] The technical scheme adopted by the present invention to solve its technical problems is realized as follows: figure 1 As shown in the schematic diagram of the power failure reporting circuit, the power failure reporting circuit includes a charging circuit (1), a farad capacitor (2), a boost circuit (3), a power failure detection and control circuit (4). figure 1 Report circuit schematic diagram for power failure; figure 2 The schematic diagram of the zero-crossing detection circuit.
[0028] Power failure detection method: The communication module detects whether the power supply voltage of the meter is lower than a certain set threshold voltage (for example, the threshold is set to 7.5V). Because the power supply of the meter has a large-capacity energy storage capacitor, and the communication module The energy storage capacitor is small. When the communication module detects that the power supply voltage of the meter is lower than the threshold voltage, when the power-off state is maintained for a period of time (for example, the power-off state position is 10ms), it is still in the power-off state, indicating that the voltage provided by the meter has dropped slowly and the communication The module is plugged into the meter; when the power-down state disappears quickly (for example, the power-down state is maintained for 2ms), it means that the voltage provided by the meter is powered down quickly. When it is detected that the power supply voltage of the meter at this time is lower than a set threshold voltage (such as When the threshold is set to 2.5V) or less, it is considered that the communication module is unplugged, and the boost circuit is enabled and turned off through circuit control to prevent the communication module from supplying power through the energy storage unit. In addition, this status is notified to the carrier chip, and power failure reporting is prohibited. Prevent false alarms of power failure; at the same time, when the power is off, the carrier chip will detect the zero-crossing signal of the power grid multiple times to judge the power-down state. If no zero-crossing signal is detected multiple times, it is considered to be in the power-down state, which increases the accuracy of power-off detection .
[0029] Circuit function introduction: When the power grid and the electric meter are normally powered, even if the voltage provided by the electric meter to the communication module is lower than 12V, the communication module only provides 12V power supply from the electric meter, and the farad capacitor and its boost circuit do not work to prevent the device from being low. Under voltage conditions, the power supply system will oscillate. When the power failure detection and control circuit (4) detects that the 12V power supply of the meter is normal, the power failure detection and control circuit (4) controls the enable of the charging circuit to be turned on, and the enable of the boost circuit is turned off. At this time, the charging circuit (1) ) Start charging the farad capacitor (2) until the charge is full, and at the same time inform the power line carrier chip of the normal power supply status of IN12V through DET_V.
[0030] When the power grid fails or the meter is abnormal and causes a sudden power failure, the communication module is powered by the farad capacitor, but does not provide power to the meter. This is because if the farad capacitor of the communication module supplies power to the meter through the 12V pin at the same time, it may be It affects the power-down detection function of the meter, and other circuits of the meter may cause additional energy consumption. When the power-down detection and control circuit (4) detects that the 12V power supply of the meter is abnormal, the power-down detection and control circuit (4) controls the enable of the boost circuit to be turned on, and the enable of the charging circuit is turned off, and at the same time, the IN12V is turned off through DET_V The power status is notified to the power line carrier chip.
[0031] Circuit principle introduction:
[0032] 1) Charging circuit (1): Its main function is to charge the farad capacitor C40 when the meter's 12V power supply is normal, and the series voltage stabilizing circuit structure is adopted to realize constant voltage and constant current charging; the charging circuit (1) is respectively controlled by the regulator V1, limited Flow resistor R40, control transistor V2, pull-up resistor R46, reference voltage circuit TS1, R65, C43, R47, and sampling resistors R66, R50. Among them, TS1 uses the three-terminal adjustable shunt reference power supply TL431 with good thermal stability.
[0033] This circuit uses a single farad capacitor with a voltage of 2.65V. The input voltage VDD of the charging circuit can use the 3.3V or 5V power supply of the communication module, or the 12V power supply provided by the meter, which can be used to pull different voltages and different capacities. The capacitor is charged, and the output voltage of the charging circuit can be set by adjusting the values of the sampling resistors R66 and R50, and the charging current of the charging circuit can be set by setting the values of the current limiting resistors R47 and R40. R65 and C43 are used for frequency compensation of the reference voltage circuit, which can improve the transient frequency response of TL431.
[0034] 2) Farad capacitor (2): Its main function is to store energy, which is mainly composed of C40 Farad capacitor; the capacity of Farad capacitor is mainly determined by the required output power W and power supply time T. According to the formula:
[0035] Required energy Q1=W*T;
[0036] Capacitor energy storage Q2 = 0.5*C*U2;
[0037] Try to pull the voltage of the capacitor to U1, the lowest operating voltage U2 of the boost circuit, so when the farad capacitor is discharged from U1 to U2, the energy of Q1 needs to be provided, then W*T=0.5*C*(U1-U2)2 , It is obtained that C=(W*T)/[0.5*(U1-U2)2]; if the efficiency of the boost circuit is considered as η, the capacity is at least C/η. According to the above calculation results, choose the Farad capacitor closest to the standard value.
[0038] 3) Boost circuit (3): Its main function is to increase the low voltage of the farad capacitor to 12V or the required setting value, and use the boost boost circuit structure to achieve voltage increase; the boost circuit (3) is composed of a voltage stabilizing capacitor C41 , C21, power inductor L1, freewheeling diode VD6, VD7, boost chip U1, pull-up resistor R45 and feedback circuit R48, R49, C42; U1 uses SX1308 boost chip, can also use the same boost function Press the chip.
[0039] The output voltage value of the boost circuit can be set by adjusting the values of R49 and R48; the function of VD6 is that when the meter is powered off, the OUT12V voltage output by the boost circuit is only supplied to the communication module, but not to the meter; R43 The main function is to supply power to the internal logic circuit of the boost chip U1 with a 3.3V or 5V power supply compatible with 12V and the communication module; the advantage of this boost circuit is that under the premise of ensuring the power supply of the internal logic circuit of the boost chip U1, the boost circuit is the lowest The input working voltage can reach 0.8V or less, so even when the voltage of a single farad capacitor is low, a stable 12V voltage can be output through this boost circuit.
[0040] 4) Power-down detection and control circuit (4): Its main function is to realize the power-down detection of the meter, the hot-plug detection of the module, the enable control of the charging circuit and the boost circuit; the control circuit is controlled by the control transistors V3, V4, V5. , Voltage divider resistors R30, R31, R59, R67, current limiting resistors R32, R60 and clamp diode VD9.
[0041] The power-down threshold voltage value can be set by adjusting the values of R59 and R67; when the IN12V voltage output by the meter is powered down, that is, when the IN12V voltage is lower than the set power-down threshold voltage, the collector of the control transistor V3 is closed to ground. When the charging circuit (1) enable is turned off and the boost circuit (3) is turned on; when the voltage of IN12V output by the meter is normal, its voltage is higher than the set power-down threshold voltage, and the collector C of the transistor V3 is controlled When it is turned on to ground, the charging circuit (1) is controlled to be turned on and the boost circuit (3) is turned off; and the IN12V power supply status is notified to the power line carrier chip through DET_V.
[0042] When the IN12V voltage is lower than the set power-down threshold voltage, it is necessary to determine whether it is caused by the unplugging of the communication module to prevent false power-down reporting; by introducing the IN12V voltage to the base of the V4 of the control transistor, when the IN12V voltage is lower than VDD When the VEB voltage of the control transistor V4 is subtracted, the control transistor V4 is turned on, through the voltage division of R31 and R30, the control transistor V5 is turned on, DET_V is forced to be pulled down, and the boost circuit (3) is enabled to be closed to prevent The communication module is powered by the farad capacitor (2), and in addition, the DET_V status is notified to the carrier chip to prohibit power-down reporting to prevent power-down false alarms;
