Power supply switching circuit suitable for intelligent electric meter and intelligent electric meter

Abstract

The utility model provides a power supply switching circuit suitable for an intelligent electric meter and the intelligent electric meter. The power supply switching circuit comprises a DC power supply loop, an energy storage loop, a battery power supply loop, a switch control unit, a clock power supply VRTC and an MCU system power supply VCC. The direct current power supply loop is connected with the energy storage loop, the battery power supply loop, the clock power supply VRTC, the MCU system power supply VCC and the switch control unit. The energy storage loop is respectively connected with a clock power supply VRTC and an MCU system power supply VCC through the switch control unit; and the battery power supply loop is respectively connected with the clock power supply VRTC and the MCU system power supply VCC. After the electricity meter is powered down for several seconds, the energy storage loop is controlled to only supply power to the clock power supply VRTC so as to ensure that the energy storage loop can supply power to the clock for more than 48 hours.

Description

Technical Field

[0001] The utility model relates to the field of smart electric meters, in particular to a power supply switching circuit suitable for smart electric meters and a smart electric meter. Background Art

[0002] The State Grid smart meter standard clearly stipulates that the battery life of smart meters should be greater than 16 years. However, in the actual use scenario of the meter, when a power outage occurs due to external reasons, the meter will be directly powered by the battery, which will affect the battery life. In order to extend the battery life, the State Grid standard stipulates that an energy storage device should be added, and the clock should be powered for at least two days when the meter is powered off to ensure the correct timing of the clock. However, for most of the current clock modules that are integrated into the MCU chip, resulting in high power consumption of the MCU chip, the power of the energy storage device is not enough to power the clock for more than 48 hours under high temperature conditions, making the MCU clock inaccurate and the meter daily timing error large. Utility Model Content

[0003] The technical problem to be solved by the utility model is to provide a power supply switching circuit and a smart meter suitable for a smart meter, so as to ensure that the clock power supply time of the energy storage component can be maintained for more than 48 hours after a power failure.

[0004] In order to solve the above technical problems, the first technical solution adopted by the utility model is:

[0005] A power supply switching circuit suitable for a smart meter, comprising a DC power supply circuit, an energy storage circuit, a switch control unit, a clock power supply VRTC and an MCU system power supply VCC;

[0006] The DC power supply circuit is respectively connected to the energy storage circuit, the clock power supply VRTC, the MCU system power supply VCC and the switch control unit; the energy storage circuit is respectively connected to the clock power supply VRTC and the MCU system power supply VCC via the switch control unit.

[0007] Optionally, the switch control unit includes a capacitor C7, a transistor Q2, a MOS transistor Q1 and a diode D5; the source of the MOS transistor Q1 is respectively connected to the anode of the diode D5 and the MCU system power supply VCC, the drain is respectively connected to the cathode of the diode D5, the clock power supply VRTC and the energy storage circuit, and the gate is connected to the collector of the transistor Q2; the base of the transistor Q2 is respectively connected to the DC power supply circuit and one end of the capacitor C7, and the other end of the capacitor C7 and the emitter of the transistor Q2 are respectively grounded.

[0008] Optionally, the switch control unit further includes a diode D4 and a diode D7;

[0009] The energy storage loop is connected to the anode of the diode D4; the cathode of the diode D4 is connected to the clock power supply VRTC and the drain of the MOS tube Q1 respectively;

[0010] The base of the transistor Q2 is connected to the DC power supply circuit via the diode D7.

[0011] Optionally, the switch control unit further includes a resistor R2, a resistor R3, a resistor R4, a resistor R6 and a resistor R7;

[0012] The drain of the MOS tube Q1 is also connected to the ground via the resistor R3 and the resistor R2 in sequence; the gate of the MOS tube Q1 is connected to the resistor R2 and the collector of the transistor Q2 respectively via the resistor R4; the base of the transistor Q2 is divided into two paths, one is connected to the cathode of the diode D7 and one end of the capacitor C7 respectively via the resistor R6, and the other is connected to the ground via the resistor R7.

[0013] Optionally, the energy storage circuit includes a diode D3, a resistor R1 and a super capacitor C6;

[0014] The anode of the diode D3 is connected to the DC power supply circuit; the cathode of the diode D3 is divided into two paths, one path is connected to the switch control unit, and the other path is connected to the ground via the resistor R1 and the super capacitor C6.

[0015] Optionally, it also includes a battery power supply circuit; the battery power supply circuit is connected to the DC power supply circuit and the MCU system power supply VCC respectively; the battery power supply circuit is also connected to the clock power supply VRTC via the switch control unit.

[0016] Optionally, the battery power supply circuit includes a diode D6, a resistor R5 and a battery; the cathode of the diode D6 is respectively connected to the DC power supply circuit, the MCU system power supply VCC and the clock power supply VRTC, and the anode is connected to the battery via the resistor R5.

[0017] Optionally, the DC power supply circuit includes an input end, a transformer, a rectifier bridge, a DC-DC circuit, a voltage regulator and an output end connected in sequence; the output end is respectively connected to an energy storage circuit, a battery power supply circuit, a clock power supply VRTC, an MCU system power supply VCC and a switch control unit.

[0018] Optionally, the DC power supply circuit further includes a diode D1 and a diode D2;

[0019] The output end is divided into three paths, one is connected to the energy storage circuit, one is connected to the switch control unit via the diode D1; and one is connected to the battery power supply circuit, the MCU system power supply VCC and the clock power supply VRTC via the diode D2.

[0020] The second technical solution adopted by the utility model is:

[0021] A smart electric meter comprises the above-mentioned power supply switching circuit applicable to the smart electric meter.

[0022] The beneficial effects of the utility model are as follows: for a high-power MCU system, the utility model divides its power supply into two independent parts, namely a clock power supply VRTC and an MCU system power supply VCC, so that when the power is off, the switch control unit is designed to control the energy storage circuit to supply power to the clock power supply VRTC and the MCU system power supply VCC at the same time, thereby meeting the MCU data preservation requirement and ensuring that the clock is not powered off; after a few seconds of power off, the switch control unit will control the energy storage circuit to supply power only to the clock power supply VRTC, thereby ensuring that the energy storage circuit can supply power to the clock for more than 48 hours. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A schematic diagram of the circuit composition and connection of a power supply switching circuit suitable for a smart meter provided in an embodiment of the utility model;

[0024] Figure 2 A circuit composition and connection diagram of a power supply switching circuit suitable for a smart meter provided in a specific embodiment of the utility model;

[0025] Figure 3 A circuit connection diagram of a power supply switching circuit suitable for a smart meter provided in an embodiment of the utility model.

[0026] Description of labels:

[0027] 1. DC power supply circuit; 2. Energy storage circuit; 3. Switch control unit; 4. Clock power supply VRTC;

[0028] 5. MCU system power supply VCC; 6. Battery power supply circuit. DETAILED DESCRIPTION

[0029] In order to explain the technical content, achieved objectives and effects of the present invention in detail, the following is an explanation in conjunction with the implementation modes and the accompanying drawings.

[0030] Please refer to Figure 1 , Figure 1 The present invention provides a circuit composition and connection diagram of a power supply switching circuit suitable for a smart meter. Figure 1As shown, the present embodiment provides a power supply switching circuit suitable for a smart meter, comprising a DC power supply circuit 1, an energy storage circuit 2, a switch control unit 3, a clock power supply VRTC 4, and an MCU system power supply VCC5. The DC power supply circuit 1 is respectively connected to the energy storage circuit 2, the clock power supply VRTC 4, the MCU system power supply VCC 5, and the switch control unit 3; the energy storage circuit 2 is respectively connected to the clock power supply VRTC 4 and the MCU system power supply VCC5 via the switch control unit 3.

[0031] The working principle of this embodiment is: the clock power supply VRTC is separated from the MCU system power supply VCC, and the two are designed independently; when the smart meter is not powered off, the DC power supply circuit supplies power to the clock power supply VRTC and the MCU system power supply VCC; after power failure, the energy storage circuit will supply power to the clock power supply VRTC and the MCU system power supply VCC respectively through the switch control unit, but after maintaining a short time sufficient for the MCU to save data, the switch control unit will cut off the path from the energy storage circuit to the MCU system power supply VCC, so that the energy storage circuit only supplies power to the clock power supply VRTC, thereby effectively extending the power supply time of the energy storage circuit and ensuring that the power supply time of the energy storage components to the clock meets the standard. Therefore, this embodiment can achieve that after the meter loses power, its clock module can still maintain operation for at least 48 hours, ensuring accurate timing of the clock; at the same time, it can also ensure the timely storage of meter data.

[0032] In some specific embodiments, Figure 2 As shown, the power supply switching circuit also includes a battery power supply circuit 6; the battery power supply circuit 6 is connected to the DC power supply circuit 1 and the MCU system power supply VCC 5 respectively; the battery power supply circuit 6 is also connected to the clock power supply VRTC 4 via the switch control unit 3.

[0033] Here, when the power level of the energy storage circuit 2 is lower than that of the battery power supply circuit 6 , the battery circuit 6 can be switched to supply power to the clock power supply VRTC 4 and the MCU system power supply VCC 5 .

[0034] In some specific embodiments, the DC power supply circuit includes an input end, a transformer, a rectifier bridge, a DC-DC circuit, a voltage regulator (preferably a three-terminal integrated voltage regulator), and an output end connected in sequence. The input end is connected to the mains; the output end is respectively connected to the energy storage circuit, the battery power supply circuit, the clock power supply VRTC, the MCU system power supply VCC, and the switch control unit.

[0035] The working principle of the above DC power supply circuit is as follows: 220V AC mains electricity flows into the DC power supply circuit from the input end, and then is converted into an AC voltage that meets the requirements through a transformer in sequence, and then filtered out interference through a rectifier bridge, and converted into DC power through a DC-DC circuit; then a stable 5.7V DC power is output through a voltage regulator, and finally flows into the circuit or unit connected to it through the output end.

[0036] Here, the DC power output by the DC power supply circuit is not only used to charge the energy storage circuit and the battery power supply circuit, but also used to power the MCU system power supply VCC and the clock power supply VRTC; further, it is also used to provide a switching signal for the switch control unit.

[0037] Specifically, if Figure 3 As shown, the DC power supply circuit 1 also includes a diode D1 and a diode D2. The output end of the DC power supply circuit (5.7V in the figure) will be divided into three paths, the first path is connected to the energy storage circuit; the second path is connected to the switch control unit via the diode D1 (corresponding to the VDD in the figure); one path is connected to the battery power supply circuit, the MCU system power supply VCC and the clock power supply VRTC respectively via the diode D2. Here, the diode D1 and the diode D2 are preferably anti-reverse charging diodes to prevent current backflow.

[0038] In some specific embodiments, Figure 3 As shown, the battery power supply circuit 6 includes a diode D6, a resistor R5 and a battery; the cathode of the diode D6 is respectively connected to the output end of the DC power supply circuit and the MCU system power supply VCC, and is connected to the clock power supply VRTC via the switch control unit; the anode of the diode D6 is connected to the battery via the resistor R5.

[0039] Wherein, the diode D6 is an anti-reverse charging diode; and the resistor R5 is a current limiting resistor.

[0040] Here, the electric energy of the battery in the battery power supply circuit will not flow out on a daily basis; and when the battery power is low, it will be charged in time through the DC power supply circuit; when the voltage of the energy storage circuit is lower than the voltage of the battery power supply circuit (such as lower than 3.6V), the switch control unit will turn on the power supply line from the battery power supply circuit to the clock power supply VRTC and the MCU system power supply VCC, so that the battery power supply circuit can supply power to the clock power supply VRTC and the MCU system power supply VCC.

[0041] See also Figure 3 This embodiment is further expanded on the basis of the above embodiment, and the specific structure of the energy storage circuit and the switch control unit are further refined.

[0042] like Figure 3As shown, the present embodiment provides a power supply switching circuit suitable for a smart meter, wherein the energy storage circuit 2 specifically includes a diode D3, a resistor R1 and a super capacitor C6. The anode of the diode D3 is connected to the output end of the DC power supply circuit (i.e., 5.7V in the figure); the cathode of the diode D3 is divided into two paths, one of which is connected to the switch control unit, and the other is connected to the resistor R1 and the super capacitor C6 in sequence and then grounded.

[0043] Wherein, the diode D3 is an anti-reverse charging diode; and the resistor R1 is a current limiting resistor.

[0044] The energy storage circuit of this embodiment has the characteristic of extremely simple structure.

[0045] The power supply switching circuit for smart meters provided in this embodiment, wherein the switch control unit specifically includes a capacitor C7, a transistor control circuit and a MOS tube control circuit; the transistor control circuit includes a transistor Q2; the MOS tube control circuit includes a MOS tube Q1 and a diode D5. The source of the MOS tube Q1 in the MOS tube control circuit is respectively connected to the anode of the diode D5 and the MCU system power supply VCC, the drain is respectively connected to the cathode of the diode D5, the clock power supply VRTC and the energy storage circuit, and the gate is connected to the collector of the transistor Q2 in the transistor control circuit; the base of the transistor Q2 is respectively connected to the DC power supply circuit and one end of the capacitor C7, and the other end of the capacitor C7 and the emitter of the transistor Q2 are respectively grounded. Here, the transistor control circuit uses the output VDD of the DC power supply circuit as a switching signal.

[0046] Preferably, the MOS transistor Q1 is a P-channel MOS transistor; and the diode D5 is a reverse current protection diode.

[0047] The working principle of the above-mentioned switch control unit is as follows: after power failure, the line from the energy storage circuit to the clock power supply VRTC is turned on, and the super capacitor in the energy storage circuit supplies power to the clock. In particular, at the moment of power failure, due to the effect of capacitor C7 in the switch control unit (C7 discharges slowly), it will be possible to ensure that the MOS tube Q1 in the MOS tube control circuit is briefly turned on (maintained for a few seconds, preferably 10s), so that the energy storage circuit can supply power to the MCU system power supply VCC to provide time for MCU data storage and processing; and when the power of capacitor C7 is exhausted, the MOS tube Q1 in the MOS tube control circuit will be cut off, and the path from the energy storage circuit to the MCU system power supply VCC will be cut off, and the energy storage circuit will no longer supply power to the MCU system. At this point, the energy storage circuit only supplies power to the clock power supply VRTC, thereby ensuring that the power supply time of the energy storage circuit can reach more than 48 hours, thereby meeting the State Grid's power supply time standard for energy storage components in electric meters. When the voltage of the energy storage circuit is lower than the voltage of the battery power supply circuit (usually 3.6V), the diode D5 in the switch control unit will be turned on, and the battery power supply circuit will supply power to the clock power supply VRTC and the MCU system power supply VCC at the same time.

[0048] In some specific implementations of this embodiment, Figure 3 As shown, the transistor control loop of the switch control unit 3 also includes a diode D7, a resistor R6 and a resistor R7. The DC power supply loop is connected to the base of the transistor Q2 via the diode D7 and the resistor R6. Here, the diode D7 is a reverse current protection diode; the resistor R6 is a current bias resistor; after passing through the diode D7 and the resistor R6, it will be able to provide a suitable current for the conduction of the transistor Q2. The base of the transistor Q2 will also be grounded via the resistor R7; one end of the capacitor C7 is specifically connected between the diode D7 and the resistor R6, and the other end is grounded.

[0049] In some specific implementations of this embodiment, Figure 3 As shown, the MOS control loop of the switch control unit 3 also includes a diode D4, a resistor R2, a resistor R3 and a resistor R4. The drain of the MOS tube Q1 is also connected to the resistor R3 and the resistor R2 in sequence and then grounded; the gate of the MOS tube Q1 is connected to one end of the resistor R4, and the other end of the resistor R4 is divided into two paths, one of which is connected to the connection line between the resistor R3 and the resistor R2, and the other is connected to the collector of the transistor Q2.

[0050] The embodiment of the utility model further provides a smart meter, which includes the power supply switching circuit applicable to the smart meter as described in any of the above embodiments. Here, the specific structure of the power supply switching circuit will not be repeated, and please refer to the description of the above embodiments for details.

[0051] The smart meter provided in this embodiment is designed independently by separating the clock power supply VRTC from the MCU system; at the same time, in conjunction with the configuration of the DC power supply circuit, the energy storage circuit, the battery power supply circuit and the switch control unit, it will be possible to realize that after the meter is powered off, the switch control unit controls the clock power supply VRTC and the MCU system power supply VCC to be powered at the same time, providing the MCU with data preservation time; in particular, after the MCU completes data preservation, that is, after the preset time, the switch control unit will cut off the power supply from the energy storage circuit to the MCU system power supply VCC, and control the energy storage circuit to only supply power to the clock power supply VRTC, thereby ensuring that the power supply time of the energy storage components of the meter for the clock meets the national grid standard. In addition, when the voltage of the energy storage circuit is too low, the switch control unit will switch the control to the battery power supply circuit to supply power to the clock power supply VRTC and the MCU system power supply VCC. Therefore, the smart meter of this embodiment will be able to ensure that its clock can maintain accurate timing for more than two days after power failure, and the MCU data can be stored in time.

[0052] In summary, the power supply switching circuit and smart meter provided by the utility model are suitable for smart meters. The meter power supply is divided into a clock power supply VRTC and an MCU system power supply VCC which are independent of each other. When the power is off, the energy storage circuit is designed to supply power to the clock power supply VRTC and the MCU system power supply VCC at the same time, which can meet the MCU data preservation requirements and ensure that the clock is not disconnected. After a few seconds, the energy storage circuit will cut off the power supply to the MCU system power supply VCC, and only the clock power supply VRTC will be supplied, so as to ensure that the energy storage circuit can supply power to the clock for more than 48 hours. In addition, when the power of the energy storage circuit is too low, the battery will be switched to supply power to the clock power supply VRTC and the MCU system power supply VCC at the same time, so as to ensure that the power-off processing of the meter meets the national grid standards.

[0053] The above description is only an embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent transformations made using the contents of the specification and drawings of the present invention, or directly or indirectly applied in the relevant technical field, are also included in the patent protection scope of the present invention.

Claims

1. A power supply switching circuit suitable for a smart meter, characterized in that: Including DC power supply circuit, energy storage circuit, switch control unit, clock power supply VRTC and MCU system power supply VCC; The DC power supply circuit is respectively connected to the energy storage circuit, the clock power supply VRTC, the MCU system power supply VCC and the switch control unit; the energy storage circuit is respectively connected to the clock power supply VRTC and the MCU system power supply VCC via the switch control unit.

2. A power supply switching circuit suitable for a smart meter as claimed in claim 1, characterized in that: The switch control unit includes a capacitor C7, a transistor Q2, a MOS transistor Q1 and a diode D5; the source of the MOS transistor Q1 is respectively connected to the anode of the diode D5 and the MCU system power supply VCC, the drain is respectively connected to the cathode of the diode D5, the clock power supply VRTC and the energy storage circuit, and the gate is connected to the collector of the transistor Q2; the base of the transistor Q2 is respectively connected to the DC power supply circuit and one end of the capacitor C7, and the other end of the capacitor C7 and the emitter of the transistor Q2 are respectively grounded.

3. A power supply switching circuit suitable for a smart meter as claimed in claim 2, characterized in that: The switch control unit also includes a diode D4 and a diode D7; The energy storage loop is connected to the anode of the diode D4; the cathode of the diode D4 is connected to the clock power supply VRTC and the drain of the MOS tube Q1 respectively; The base of the transistor Q2 is connected to the DC power supply circuit via the diode D7.

4. A power supply switching circuit suitable for a smart meter as claimed in claim 3, characterized in that: The switch control unit further includes a resistor R2, a resistor R3, a resistor R4, a resistor R6 and a resistor R7; The drain of the MOS tube Q1 is also connected to the ground via the resistor R3 and the resistor R2 in sequence; the gate of the MOS tube Q1 is connected to the resistor R2 and the collector of the transistor Q2 respectively via the resistor R4; the base of the transistor Q2 is divided into two paths, one is connected to the cathode of the diode D7 and one end of the capacitor C7 respectively via the resistor R6, and the other is connected to the ground via the resistor R7.

5. A power supply switching circuit suitable for a smart meter as claimed in claim 1, characterized in that: The energy storage circuit includes a diode D3, a resistor R1 and a super capacitor C6; The anode of the diode D3 is connected to the DC power supply circuit; the cathode of the diode D3 is divided into two paths, one path is connected to the switch control unit, and the other path is connected to the ground via the resistor R1 and the super capacitor C6.

6. A power supply switching circuit suitable for a smart meter as claimed in claim 1, characterized in that: It also includes a battery power supply circuit; the battery power supply circuit is connected to the DC power supply circuit and the MCU system power supply VCC respectively; the battery power supply circuit is also connected to the clock power supply VRTC via the switch control unit.

7. A power supply switching circuit suitable for a smart meter as claimed in claim 6, characterized in that: The battery power supply circuit includes a diode D6, a resistor R5 and a battery; the cathode of the diode D6 is respectively connected to the DC power supply circuit, the MCU system power supply VCC and the clock power supply VRTC, and the anode is connected to the battery via the resistor R5.

8. A power supply switching circuit suitable for a smart meter as claimed in claim 6, characterized in that: The DC power supply circuit includes an input end, a transformer, a rectifier bridge, a DC-DC circuit, a voltage stabilizer and an output end which are connected in sequence; the output end is respectively connected to an energy storage circuit, a battery power supply circuit, a clock power supply VRTC, an MCU system power supply VCC and a switch control unit.

9. A power supply switching circuit suitable for a smart meter as claimed in claim 8, characterized in that: The DC power supply circuit also includes a diode D1 and a diode D2; The output end is divided into three paths, one is connected to the energy storage circuit, one is connected to the switch control unit via the diode D1; and one is connected to the battery power supply circuit, the MCU system power supply VCC and the clock power supply VRTC via the diode D2.

10. A smart electric meter, characterized in that: A power supply switching circuit suitable for a smart meter comprising the power supply switching circuit described in any one of claims 1 to 9 above.

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