WO2019218882A1

WO2019218882A1 - Super-capacitor application circuit of replaceable battery type smart electric energy meter power supply

Info

Publication number: WO2019218882A1
Application number: PCT/CN2019/085600
Authority: WO
Inventors: 石荣; 吴红英; 徐振伟; 李香; 郎干勇; 朱高凯; 潘建华; 刘静; 杨永广
Original assignee: 扬州万泰电子科技有限公司
Priority date: 2018-05-18
Filing date: 2019-05-06
Publication date: 2019-11-21
Also published as: CN108429332B; CN108429332A

Abstract

A super-capacitor application circuit of a replaceable battery type smart electric energy meter power supply. The circuit comprises a transformer T1, a rectifying circuit, a voltage stabilizing circuit and a sampling circuit, and further comprises a dual-super-capacitor clock backup power supply circuit. The dual-super-capacitor clock backup power supply circuit comprises a clock chip, an electric energy meter processing unit, an anti-reverse diode D5, a super-capacitor C6 and a charge-discharge resistor R6, wherein an input end of the super-capacitor C6 is connected to an output end of the charge-discharge resistor R6, and an output end of the super-capacitor C6 is grounded. Therefore, the trickle charge current is very low, and the service life of the super-capacitors C4 and C6 is prolonged.

Description

Supercapacitor application circuit for battery replaceable smart energy meter power supply

Technical field

The invention relates to a smart electric energy meter, in particular to a super capacitor application circuit of a battery replaceable smart electric energy meter power supply.

Background technique

The timing function of the smart energy meter is very important, which will affect important functions such as billing and event recording. It is required that the clock module must work normally even in the event of power failure. For this reason, a lithium battery is used as a clock backup power source inside the smart energy meter to ensure The clock module works normally during a power outage. However, lithium batteries have a passivation effect for a long time, which shortens the battery life, so it needs to be replaced after a period of use. However, the original smart energy meter clock battery is soldered to the power meter circuit board, so the replacement is inconvenient, and the replacement battery must be in the power-off state. In order to solve the problem that the battery cannot be replaced when the single-phase smart energy meter clock battery is under voltage, the State Grid Metrology Center has taken the lead in formulating the technical requirements of the battery replaceable smart energy meter, which not only improves the battery installation structure for battery replacement, but also ensures battery replacement. During the normal operation of the clock module, it is required to install a super capacitor in the electric energy meter, and in June 2016, it was publicized to the electric energy meter manufacturer. It is required that when the power meter is powered off and the battery is under voltage, the super capacitor only supplies power to the clock and keeps the clock clocked correctly for at least 2 days. The detection process of the State Grid Metrology Center is: after the electric energy meter is loaded for 10 minutes under the reference voltage condition, the electric energy meter clock is compared with the standard time, and then the clock battery is taken out and the electric energy meter is powered off, and the ambient temperature is -40 ° C. , let stand for 2 days. Put the clock battery back into the battery compartment of the energy meter, power on the energy meter, and the error between the power meter clock and the standard time should not exceed 5s. Repeat the above operation with the same smart energy meter at an ambient temperature of 70 ° C and meet the same requirements.

The supercapacitor charging and discharging circuit is simple, and there is no need for a charging circuit like a rechargeable battery. Therefore, the clock standby power supply in the battery replaceable electric energy meter is generally realized by a series circuit in which a super capacitor and a charging and discharging resistor are externally connected to the power output end. The advantage of using this method is that the circuit is simple to implement, but the disadvantages are:

(1) Since the electric energy meter is required to be de-energized after being loaded for a certain period of time under the reference voltage condition during the detection, the supercapacitor must be fully charged during this period, which requires that the charging resistor must be as much as possible under the premise of the supercapacitor. Small to speed up charging, and a big advantage of supercapacitors over lithium batteries is that they allow large currents to be charged and discharged without damage. However, since the charging resistor and the discharging resistor are the same resistor, this causes the discharging speed to be fast, so that the super capacitor holding time is reduced.

(2) Under the condition that the performance of the super capacitor is reduced or the power failure is far more than 2 days, the super capacitor maintenance time cannot meet the requirements.

Summary of the invention

The present invention is directed to the above problem, and provides a super capacitor application circuit of a battery replaceable smart energy meter power supply with low power consumption and long super capacitor maintenance time.

The technical solution of the present invention comprises: a transformer T1, a rectifying circuit, a voltage stabilizing circuit and a sampling circuit; and a double super capacitor clock standby power supply circuit;

The dual super capacitor clock backup power supply circuit comprises a clock chip, an electric energy meter processing unit, an anti-reverse diode D5, a super capacitor C6 and a charging and discharging resistor R6;

The clock chip includes a main power terminal Vcc2, a backup power terminal Vcc1, a chip select signal terminal CE, a data signal terminal I/O, and a communication clock signal SCLK; the main power terminal Vcc2 is connected to a voltage stabilizing circuit, and the backup power terminal Vcc1 is connected to the anode of the anti-reverse diode D5, and the chip select signal terminal CE, the data signal terminal I/O and the communication clock signal SCLK are respectively connected to corresponding ends of the electric energy meter processing unit;

The charging and discharging resistor R6 is connected in parallel with the sampling circuit, and is respectively connected to the negative electrode of the anti-reverse diode D5;

An input end of the super capacitor C6 is connected to an output end of the charging and discharging resistor R6, and an output end of the super capacitor C6 is grounded.

The clock chip uses a DS1302 low power clock chip.

The rectifier circuit includes a rectifier V1, a capacitor C1 and a capacitor C2;

The primary input end of the transformer T1 is connected to 220V mains; the input end of the rectifier V1 is connected to the secondary output end of the transformer T1;

The capacitor C1 and the capacitor C2 are connected in parallel, and the input ends thereof are respectively connected to the third pin of the rectifier V1, and the output ends thereof are respectively grounded.

The voltage stabilizing circuit comprises a three-terminal regulator U1, a common anode double diode D1, a common anode double diode D2, a capacitor C3, a resistor R1 and a super capacitor C4;

The first pin of the three-terminal regulator U1 is connected to the output end of the rectifier V1, and the second pin of the three-terminal regulator U1 is connected to the input end of the common anode double diode D1, the common anode double diode The output of D1 is grounded;

The common anode double diode D2 and the capacitor C3 are connected in parallel;

The positive input terminal of the capacitor C3 is connected to the third pin of the three-terminal regulator U1, and the negative output terminal of the capacitor C3 is grounded;

The third pin of the common anode dual diode D2 is connected to the third pin of the three-terminal regulator U1;

The resistor R1 and the super capacitor C4 are connected in series, the input end of the resistor R1 is connected to the first pin of the common anode dual diode D2, and the output end of the super capacitor C4 is grounded.

The input end of the capacitor C1 is provided with a detection circuit;

The detecting circuit includes a resistor R4 and a resistor R5; an input end of the resistor R4 is connected to a second pin of the common anode double diode D2; an input end of the resistor R5 is connected to an output end of the resistor R4, The output of the resistor R5 is grounded;

The electric energy meter processing unit is connected between the resistor R4 and the resistor R5.

The sampling circuit comprises a common cathode double diode D3, a diode D4, a clock battery, a resistor R2, a resistor R3 and a capacitor C5;

a first pin of the common cathode dual diode D3 is connected to a first pin of the common anode dual diode D2, and a third pin of the common cathode double diode D3 is connected to an electric energy meter processing unit, the diode D4 The negative output terminal is also connected to the electric energy meter processing unit, and the input end of the diode D4 is connected to a voltage of 5.7V;

One end of the resistor R3 is connected to the positive pole of the battery, and the other end is connected to the electric energy meter processing unit; one end of the capacitor C5 is connected to the electric energy meter processing unit, and the other end is grounded; one end of the resistor R2 is connected to the electric energy meter processing unit. The other end is grounded; the negative pole of the battery is grounded; the second pin of the common cathode dual diode D3 is connected between the resistor R3 and the battery.

In the present invention, in order to extend the duration of the clock backup power supply, a dual super capacitor clock backup power supply circuit is employed. On the basis of the existing single super capacitor clock backup power supply circuit, as shown in FIG. 2, a circuit as shown in FIG. 1 is added between the power supply V B and the one end of the common cathode double diode D3. The circuit is composed of a clock chip DS1302, a power meter processing unit, an anti-reverse diode D5, a super capacitor C6, and a charge and discharge resistor R6. At the same time, the V DC power supply in FIG. 2 is divided by the resistors R4 and R5 and sent to the power meter processing unit for detection to determine whether the power meter is powered off.

The circuit has the following characteristics: (1) Since the DS1302 is a general-purpose, inexpensive clock chip, and the number of electric energy meters is large, it is more than 100,000, so the price of the DS1302 is very low when purchased in bulk, so it will not be on the electric energy meter. The cost increases a lot; (2) The power consumption of the DS1302 is low when it is working. The operating current is less than 300nA at 2V, and the power consumption is less than 1mW when maintaining data and clock information. Since the clock function is not used in the present invention, there is no need to maintain data and clock information, and no external crystal oscillator is used to generate the clock. At the same time, after the power meter processing unit configures the trickle charge register of the DS1302, no communication is required between the power meter processing unit and the DS1302. Therefore, the power consumption increased by this circuit is extremely low. (3) In Figure 2, when the energy meter is working normally, the VCC power supply is provided by the output of the three-terminal regulator U1 at 5.7V, so the lifetime of the super capacitors C4 and C6 is little affected. When the clock battery is under voltage, the power meter is powered off by the super capacitors C4 and C6. Under the premise of satisfying the power consumption, the current meter processing unit configures the DS=10 of the trickle charge register, RS=11, that is, selects two diodes, selects the resistor R3=8KΩ, and the charging loop resistance is large, so the trickle charging current is small. Extends the life of supercapacitors C4 and C6.

DRAWINGS

1 is a circuit diagram of a dual super capacitor clock backup power supply of the present invention;

2 is a circuit diagram of a single super capacitor clock standby power supply;

Figure 3 is a circuit configuration diagram of the present invention;

Figure 4 is the working circuit of the DS1302 clock chip;

Figure 5 is an internal structure diagram of the DS1302 clock chip;

6 is a circuit diagram of a trickle charging power supply inside the DS1302 clock chip;

In the figure, POWER CONTROL is the power control device, INPUT SHIFT REGISTERS is the input shift register, COMMAND AND CONTROL LOGLC is the command and control system, REAL TIME CLOCK is the real-time clock,

1 OF 16 SELECT is 16 for 1, NOTE: ONLY 1010 ENABLES CHARGER is Note: Only 1010 can charge, 1 OF 2 SELECT is 2, 1, 1 OF 3 SELECT is 3

TCS=TRICKLE CHARGER SELECT is TCS=Trickle Charger Selection,

DS=DIODE SELECT is DS=diode selection,

ROUT=RESISTOR SELECT is ROUT=resistor selection.

Detailed ways

The present invention, as shown in FIGS. 1-6, includes a transformer T1, a rectifier circuit, a voltage stabilization circuit, and a sampling circuit; and is characterized in that it further includes a dual super capacitor clock backup power supply circuit;

The dual super capacitor clock backup power supply circuit comprises a clock chip, a power meter processing unit (ie, a CPU), an anti-reverse diode D5, a super capacitor C6, and a charging and discharging resistor R6;

The clock chip uses a DS1302 low power clock chip.

In order to overcome the shortcomings of the above-mentioned power meter clock backup power supply, the present invention adopts the DS1302 low-power real-time clock chip with fine current charging capability introduced by DALLAS, USA, which fully utilizes the advantages of its dual power supply and internal programmable fine current charging circuit. Invented a dual supercapacitor clock backup power supply that greatly extends the duration of the clock backup power supply with extremely limited cost and power consumption.

The DS1302 is a low-power real-time clock chip with a fine current charging capability introduced by DALLAS, USA. DS1302 is a high-performance, low-power, real-time clock circuit with RAM from DALLAS. It can time the year, month, day, week, hour, minute and second. It has leap year compensation function and the working voltage is 2.0V ~ 5.5V. The DS1302 provides dual power supply pins for the main power supply and the backup power supply. Vcc2 is the main power supply, and VCC1 is the backup power supply. It also provides the ability to charge the backup power supply with fine current. The continuous operation of the clock can also be maintained with the main power off. The DS 1302 is powered by the larger of Vcc1 or Vcc2. When Vcc2 is greater than Vcc1+0.2V, it is powered by Vcc2. When Vcc2 is less than Vcc1, it is powered by Vcc1.

Figure 4 shows the typical working circuit of the DS1302 clock chip. Among them, CE is the chip select signal, I/O is the data signal, SCLK is the communication clock signal, and X1 and X2 are the crystal oscillator signals. Figure 3 shows the internal structure of the DS1302 clock chip. As can be seen from the figure, the DS1302 mainly includes an oscillation circuit module, a data memory RAM, a command and control logic module, an input shift register, and a power control module.

Important to the present invention is the power control module. Among them, the most important thing is that the module contains a special register - trickle charge register, by programming the register, you can determine the charge or not and the charge current. Therefore, the trickle charge register determines the charging characteristics of the DS1302. Figure 6 shows the internal trickle charge power supply circuit diagram of the DS1302 clock chip.

Among them, TCS is the trickle charge selection bit, DS is the diode select bit, and RS is the resistor select bit. When TCS=1010, trickle charge is enabled; when TCS is other, trickle charge is disabled. When the DS1302 clock chip is powered on, there is no trickle charge. The power meter processing is required to initialize the TCS bit to the trickle charge mode. If DS=01, select a diode; if DS=10, select two diodes; if DS=00 or 11, even if TCS=1010, the charging function is disabled. If RS=01, select resistor R1=2KΩ; if RS=10, select resistor R2=4KΩ; if RS=11, select resistor R3=8KΩ; RS≠00. RS and DS are determined by the maximum charging current of external VCC1 and VCC2.

The input end of the capacitor C1 is provided with a detection circuit;

As shown in FIG. 2, the existing common energy meter clock backup power supply. The grid voltage is isolated and stepped down by the transformer T1 and then connected to the input terminal of the rectifier module V1. The DC voltage V DC output from the rectifier module V1 is connected to the input terminal of the three-terminal regulator U1, and the ground terminal of the three-terminal regulator passes through the common anode. The double diode D1 is grounded to raise the output voltage of the three-terminal regulator to 5.7V. The output voltage of the three-terminal regulator is 5.7V connected to the anode of the common anode dual diode D2, the cathode of the double diode D2 is output voltage VDD, the communication module of the power supply table works, and the other cathode output voltage V B is connected. One anode end of the cathode double diode D3, the other anode end of the double diode D3 is connected to the anode of the clock battery, the cathode output of the double diode D3 and the output of the 5.7V diode D4 together form the main and auxiliary power sources of the power meter processing unit CPU The electric energy meter clock is a built-in clock of the CPU. The resistors R2, R3 and the capacitor C5 constitute a step-down sampling circuit of the clock battery, and the CPU determines whether the clock battery is under voltage by the sampling value. When the clock battery is under voltage, an alarm signal is output in the energy meter processing unit to instantly replace the clock battery.

The invention is composed of an anti-reverse diode D5, a super capacitor C6 and a charge and discharge resistor R6. At the same time, the V DC power supply in Figure 1 is divided by resistors R4 and R5 and sent to the CPU for detection to determine whether the energy meter is powered off.

The working principle of the dual super capacitor clock backup power supply circuit adopted by the invention is as follows: when the energy meter is initially powered on, the CPU configures the trickle charge register of the clock chip DS1302 as follows: TCS=1010, DS=01, RS=01, even if it can Stream charging, select a diode, select resistor R1 = 2KΩ, in order to quickly charge the super capacitor C6. Since the DS1302's trickle charging circuit already contains a diode, in order to ensure that the super capacitor C6 is charged to the highest possible voltage, the diode D5 should be of the type with the smallest forward voltage. When the energy meter is powered off, the output voltage of the three-terminal regulator U1 in Figure 2 will gradually drop to 0V due to the function of the storage capacitor C1. The threshold voltage can be set to 9V. When the CPU detects that the V DC is less than 9V, the power meter can be considered to be powered off. However, the CPU's working power supply VCC is still in the normal working state, so the CPU has not entered the low power state. The CPU quickly configures the DS=10 of the trickle charge register, RS=11, that is, selects two diodes and selects the resistor R3=8KΩ. When the output voltage of the three-terminal regulator U1 is 0, if the clock battery is also under voltage, the clock module of the energy meter is completely powered by the super capacitors C4 and C6. When the voltage of the super capacitor C6 drops to a certain value, the super capacitor C4 replenishes energy through the trickle charging circuit, thereby greatly prolonging the maintenance time of the clock module and ensuring the accuracy of the meter timing.

The circuit has the following characteristics: (1) Since the DS1302 is a general-purpose, inexpensive clock chip, and the number of electric energy meters is large, it is more than 100,000, so the price of the DS1302 is very low when purchased in bulk, so it will not be on the electric energy meter. The cost increases a lot; (2) The power consumption of the DS1302 is low when it is working. The operating current is less than 300nA at 2V, and the power consumption is less than 1mW when maintaining data and clock information. Since the clock function is not used in the present invention, there is no need to maintain data and clock information, and no external crystal oscillator is used to generate the clock. At the same time, after the CPU configures the trickle charge register of the DS1302, no communication is required between the CPU and the DS1302. Therefore, the power consumption increased by this circuit is extremely low. (3) In Figure 1, when the energy meter is working normally, the VCC power supply is provided by the output of the three-terminal regulator U1 at 5.7V, so the lifetime of the super capacitors C4 and C6 is little affected. When the clock battery is under voltage, the power meter is powered off by the super capacitors C4 and C6. Under the premise of satisfying the power consumption, the CPU configures the trickle charge register DS=10, RS=11, that is, selects two diodes, selects the resistor R3=8KΩ, and the charging loop resistance is large, so the trickle charging current is small and prolonged. The life of super capacitors C4 and C6.

Claims

A supercapacitor application circuit for a battery replaceable smart energy meter power supply, comprising a transformer T1, a rectifier circuit, a voltage stabilization circuit and a sampling circuit; and characterized in that it further comprises a double super capacitor clock backup power supply circuit;

The dual super capacitor clock backup power supply circuit comprises a clock chip, an electric energy meter processing unit, an anti-reverse diode D5, a super capacitor C6 and a charging and discharging resistor R6;

The clock chip includes a main power terminal Vcc2, a backup power terminal Vcc1, a chip select signal terminal CE, a data signal terminal I/O, and a communication clock signal SCLK; the main power terminal Vcc2 is connected to a voltage stabilizing circuit, and the backup power terminal Vcc1 is connected to the anode of the anti-reverse diode D5, and the chip select signal terminal CE, the data signal terminal I/O and the communication clock signal SCLK are respectively connected to corresponding ends of the electric energy meter processing unit;

The charging and discharging resistor R6 is connected in parallel with the sampling circuit, and is respectively connected to the negative electrode of the anti-reverse diode D5;

An input end of the super capacitor C6 is connected to an output end of the charging and discharging resistor R6, and an output end of the super capacitor C6 is grounded.
The supercapacitor application circuit of a battery replaceable smart energy meter power supply according to claim 1, wherein the clock chip uses a DS1302 low power clock chip.
The supercapacitor application circuit of a battery replaceable smart energy meter power supply according to claim 1, wherein the rectifier circuit comprises a rectifier V1, a capacitor C1 and a capacitor C2;

The primary input end of the transformer T1 is connected to 220V mains; the input end of the rectifier V1 is connected to the secondary output end of the transformer T1;

The capacitor C1 and the capacitor C2 are connected in parallel, and the input ends thereof are respectively connected to the third pin of the rectifier V1, and the output ends thereof are respectively grounded.
The supercapacitor application circuit of a battery replaceable smart energy meter power supply according to claim 3, wherein the voltage stabilizing circuit comprises a three-terminal regulator U1, a common anode double diode D1, a common anode double diode D2, capacitor C3, resistor R1 and super capacitor C4;

The first pin of the three-terminal regulator U1 is connected to the output end of the rectifier V1, and the second pin of the three-terminal regulator U1 is connected to the input end of the common anode double diode D1, the common anode double diode The output of D1 is grounded;

The common anode double diode D2 and the capacitor C3 are connected in parallel;

The positive input terminal of the capacitor C3 is connected to the third pin of the three-terminal regulator U1, and the negative output terminal of the capacitor C3 is grounded;

The third pin of the common anode dual diode D2 is connected to the third pin of the three-terminal regulator U1;

The resistor R1 and the super capacitor C4 are connected in series, the input end of the resistor R1 is connected to the first pin of the common anode dual diode D2, and the output end of the super capacitor C4 is grounded.
The supercapacitor application circuit of a battery replaceable smart energy meter power supply according to claim 4, wherein the input end of the capacitor C1 is provided with a detecting circuit;

The detecting circuit includes a resistor R4 and a resistor R5; an input end of the resistor R4 is connected to a second pin of the common anode double diode D2; an input end of the resistor R5 is connected to an output end of the resistor R4, The output of the resistor R5 is grounded;

The electric energy meter processing unit is connected between the resistor R4 and the resistor R5.
The supercapacitor application circuit of a battery replaceable smart energy meter power supply according to claim 4, wherein the sampling circuit comprises a common cathode double diode D3, a diode D4, a clock battery, a resistor R2, a resistor R3, and Capacitor C5;

a first pin of the common cathode dual diode D3 is connected to a first pin of the common anode dual diode D2, and a third pin of the common cathode double diode D3 is connected to an electric energy meter processing unit, the diode D4 The negative output terminal is also connected to the electric energy meter processing unit, and the input end of the diode D4 is connected to a voltage of 5.7V;

One end of the resistor R3 is connected to the positive pole of the battery, and the other end is connected to the electric energy meter processing unit; one end of the capacitor C5 is connected to the electric energy meter processing unit, and the other end is grounded; one end of the resistor R2 is connected to the electric energy meter processing unit. The other end is grounded; the negative pole of the battery is grounded; the second pin of the common cathode dual diode D3 is connected between the resistor R3 and the battery.