Load switch driving system and method based on linear power supply of intelligent electric energy meter

Abstract

The invention relates to the technical field of intelligent electric energy meter power supplies, in particular to a load switch driving system and method based on an intelligent electric energy meter linear power supply. A linear power supply module isolates, reduces, rectifies and filters alternating-current voltage and outputs first direct-current voltage, and the first direct-current voltage passes through a DC-DC voltage reduction module to obtain second direct-current voltage; the second direct-current voltage supplies power to the MCU microcontroller and also supplies constant-voltage charging to the farad capacitor energy storage module, charging of the energy storage module can be completed in a short time, when the MCU microcontroller of the electric energy meter receives a switching-on / switching-off instruction, the control module sends out a boosting enabling signal, the DC-DC boosting module is started, the farad capacitor end voltage pump is boosted to the third direct-current voltage, and the farad capacitor energy storage module is started. The driving module outputs large-current pulse to drive the high-power load switch to act reliably, the action is completed, the DC-DC boosting module is closed, the low-power-consumption normal state is recovered, if a power grid is powered down, the farad capacitor can prolong the dormancy operation time of the electric energy meter, and the accuracy of an internal clock is guaranteed.

Description

Technical Field

[0001] This invention relates to the field of smart energy meter power supply technology, and in particular to a load switch drive system and method based on the linear power supply of a smart energy meter. Background Technology

[0002] Currently, smart meters generally use linear power supplies, with an output power typically below 3.5VA, which is sufficient to meet conventional functions such as metering and communication. However, as smart grids continuously increase the requirements for performance indicators such as overload capacity, contact resistance, and electrical clearance of load switches, the transient drive power of load switches has risen to 9W~12W, while the operating time is required to be shortened to within 30ms.

[0003] In existing technologies, to compensate for the power gap in linear power supplies, the linear power supply is usually directly replaced with a high-power switching power supply. While this approach can meet transient power requirements, it brings drawbacks such as high cost, complex EMI, long development cycles, and insufficient field operation experience, severely restricting the economic efficiency and reliability of smart meters. Therefore, there is an urgent need for a new system and method that can reliably drive high-power load switches without replacing the linear power supply. Summary of the Invention

[0004] The purpose of this invention is to provide a load switch driving system and method based on the linear power supply of a smart energy meter, which aims to solve the problem that existing low-power linear power supplies cannot directly drive high-power load switches.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a load switch drive system based on a linear power supply of a smart energy meter, comprising a linear power supply module, a DC-DC step-down module, a supercapacitor energy storage module, a DC-DC boost module, a control module, a drive module, and a load switch module. The linear power supply module, the DC-DC step-down module, the supercapacitor energy storage module, the DC-DC boost module, the drive module, and the load switch module are connected in sequence, and the control module is connected to the DC-DC boost module and the drive module. The linear power supply module is used to isolate and step down the mains voltage and output a first DC voltage; The DC-DC step-down module is used to reduce the first DC voltage to the second DC voltage; The supercapacitor energy storage module is used to charge and store transient drive energy with a second DC voltage; The DC-DC boost module is used to boost the voltage of the supercapacitor to the third DC voltage required by the load switch when enabled; The control module is used to enable the DC-DC boost module before the load switch operates and to turn off the DC-DC boost module after the power grid fails to reduce static power consumption. The drive module is used to output drive current under the power supply of a third DC voltage; The load switch module is used to perform on / off actions based on the drive current.

[0006] The linear power supply module includes a power frequency transformer unit, a full-bridge rectifier unit, and a π-type filter unit. The power frequency transformer unit is used to isolate and step down the 220V AC mains voltage to a low voltage AC. The full-bridge rectifier unit is used to rectify low-voltage AC into pulsating DC. The π-type filter unit is used to suppress ripple and output a first DC voltage.

[0007] The DC-DC buck module includes a PWM controller unit, a power MOSFET unit, an energy storage inductor unit, an output capacitor unit, and a feedback voltage divider unit. The PWM controller unit is used to generate a switching signal with an adjustable duty cycle; The power MOSFET unit is used to perform high-frequency switching operations; The energy storage inductor unit is used for energy storage and output smoothing; The output capacitor unit is used to filter out high-frequency ripple; The feedback voltage divider unit is used to sample the output voltage and feed it back to the PWM controller unit to stabilize the second DC voltage.

[0008] The supercapacitor energy storage module includes a supercapacitor unit, a current-limiting resistor unit, a reverse protection diode unit, and a voltage-equalizing resistor unit. The supercapacitor unit is used for large-capacity energy storage using a second DC voltage. The current-limiting resistor unit is used to charge the supercapacitor with the second DC voltage through a constant resistance method, limiting the excessive current at the beginning of charging to prevent the DC-DC module from overcurrent protection. The anti-reverse diode unit is used to prevent the supercapacitor from discharging in reverse to the DC-DC step-down module; The voltage equalization resistor unit is used to maintain the long-term voltage balance between the individual cells when the two individual supercapacitors are used together.

[0009] The DC-DC boost module includes a boost controller unit, a boost inductor unit, a synchronous rectifier MOSFET unit, an output rectifier diode unit, an adjustable feedback unit, and an output capacitor unit. The boost controller unit is used to initiate boost voltage upon triggering by the control module; The boost inductor unit is used for energy storage and transmission; The synchronous rectifier MOSFET unit is used to perform high-frequency switching operations; The output rectifier diode unit is used to isolate the input and output terminals; The adjustable feedback unit is used to set the third DC voltage by adjusting the voltage divider resistor; The output capacitor unit is used to smooth the DC output after boosting.

[0010] The control module includes a power failure detection unit, a boost enable unit, a timing logic unit, and a communication interface unit. The power failure detection unit is used to monitor the grid voltage in real time and generate a power failure signal when power fails. The boost enable unit is used to control the start and stop of the DC-DC boost module according to the load switch operation command or power failure signal; The timing logic unit is used to coordinate the timing of supercapacitor charging, boost startup, and drive signal issuance. The communication interface unit is used to interact with the external main control MCU to exchange switch action commands and status information.

[0011] Secondly, a load switch driving method based on a linear power supply of a smart energy meter, used in the load switch driving system based on a linear power supply of a smart energy meter as described in the first aspect, includes the following steps: The linear power module isolates and steps down the mains voltage to a first DC voltage; The DC-DC step-down module reduces the first DC voltage to the second DC voltage and charges the supercapacitor energy storage module. The control module enables the DC-DC boost module when it receives a load switch operation command; The DC-DC boost module boosts the voltage of the supercapacitor to a third DC voltage and supplies power to the drive module; The drive module uses a third DC voltage to drive the load switch module to complete the switching action; When the power grid fails, the control module shuts down the DC-DC boost module to reduce the energy consumption of the supercapacitor.

[0012] The load switch drive system based on the linear power supply of a smart energy meter of the present invention, after the system is powered on, the linear power supply module first isolates, steps down, rectifies and filters the 220V AC grid voltage, and outputs a stable first DC voltage (typically 20V). This voltage enters the DC-DC step-down module, and after PWM modulation and LC filtering, a second DC voltage (typically 5V) is obtained. This second DC voltage is then used to charge the supercapacitor energy storage module at a constant voltage using a current-limiting method. Within 30 seconds, the energy required for one load switch operation is completed without continuously supplying power to subsequent stages, thus not increasing the long-term burden on the linear power supply. When the control module receives the "closing / opening" command, it immediately issues a boost enable signal: the DC-DC boost module starts instantaneously, pumping the voltage at the supercapacitor terminals to the third DC voltage (typically 12V) required by the load switch with an efficiency of over 85%. The drive module outputs a large current pulse at this voltage, directly driving the load switch coil, enabling it to complete a reliable operation within ≤30ms. After the operation is completed, the control module turns off the boost enable, the DC-DC boost module stops working, and the system returns to low-power normal operation. If the power grid fails, the power failure detection unit cuts off the boost enable within 10ms, and the supercapacitor only provides a μA-level sustaining current to the metering MCU, significantly extending the sleep time of the energy meter. This solves the problem that existing technologies cannot directly drive high-power load switches with low-power linear power supplies. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a schematic diagram of a load switch drive system based on a linear power supply of a smart energy meter provided by the present invention.

[0015] Figure 2 This is a schematic diagram of a linear power supply module.

[0016] Figure 3 This is a schematic diagram of a DC-DC step-down module.

[0017] Figure 4 This is a schematic diagram of a farad capacitor energy storage module.

[0018] Figure 5 This is a schematic diagram of a DC-DC boost module.

[0019] Figure 6 This is a schematic diagram of the control module.

[0020] Figure 7This is a schematic diagram of the driver module.

[0021] Figure 8 This is a schematic diagram of a load switch module.

[0022] Figure 9 This is the circuit diagram of a DC-DC step-down module.

[0023] Figure 10 This is the circuit diagram of a farad capacitor energy storage module.

[0024] Figure 11 This is the circuit diagram of a DC-DC boost module.

[0025] Figure 12 This is the circuit diagram of the driver module.

[0026] Figure 13 This is a flowchart of the load switch driving method based on the linear power supply of a smart energy meter provided by the present invention.

[0027] In the diagram: 1-Linear power supply module, 2-DC-DC step-down module, 3-Faraday capacitor energy storage module, 4-DC-DC boost module, 5-Control module, 6-Drive module, 7-Load switch module, 11-Power frequency transformer unit, 12-Full-bridge rectifier unit, 13-π-type filter unit, 21-PWM controller unit, 22-Power MOSFET unit, 23-Energy storage inductor unit, 24-Output capacitor unit, 25-Feedback voltage divider unit, 31-Faraday capacitor unit, 32-Current limiting resistor unit, 33-Reverse protection diode unit, 34-Voltage equalizing capacitor. 41-Boost controller unit, 42-Boost inductor unit, 43-Synchronous rectifier MOSFET unit, 44-Output rectifier diode unit, 45-Adjustable feedback unit, 46-Output capacitor unit, 51-Power-down detection unit, 52-Boost enable unit, 53-Timing logic unit, 54-Communication interface unit, 61-Driver chip unit, 62-Gate resistor unit, 63-Energy storage electrolysis unit, 64-Protection TVS unit, 65-Current sampling unit, 71-Magnetic latching relay unit, 72-Auxiliary contact unit, 73-Arc extinguishing unit. Detailed Implementation

[0028] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0029] Please see Figures 1 to 12In a first aspect, the present invention provides a load switch drive system based on the linear power supply of a smart energy meter, comprising a linear power supply module 1, a DC-DC step-down module 2, a supercapacitor energy storage module 3, a DC-DC boost module 4, a control module 5, a drive module 6, and a load switch module 7. The linear power supply module 1, the DC-DC step-down module 2, the supercapacitor energy storage module 3, the DC-DC boost module 4, the drive module 6, and the load switch module 7 are connected in sequence, and the control module 5 is connected to the DC-DC boost module 4 and the drive module 6. The linear power supply module 1 is used to isolate and step down the grid voltage and output a first DC voltage; The DC-DC step-down module 2 is used to reduce the first DC voltage to the second DC voltage; The supercapacitor energy storage module 3 is used to charge and store transient drive energy with a second DC voltage; The DC-DC boost module 4 is used to boost the voltage of the supercapacitor to the third DC voltage required by the load switch when enabled; The control module 5 is used to enable the DC-DC boost module 4 before the load switch operates, and to turn off the DC-DC boost module 4 after the power grid fails to reduce static power consumption. The drive module 6 is used to output drive current under the power supply of the third DC voltage; The load switch module 7 is used to perform on / off actions based on the drive current.

[0030] In this embodiment, after the system is powered on, the linear power supply module 1 first isolates, steps down, rectifies, and filters the 220V AC mains voltage to output a stable first DC voltage (typically 20V). This voltage enters the DC-DC step-down module 2, and after PWM modulation and LC filtering, a second DC voltage (typically 5V) is obtained. This second DC voltage is then used to charge the supercapacitor energy storage module 3 at a constant voltage using a current-limiting method. Within 30 seconds, the energy storage required for one load switch operation is completed without continuously supplying power to subsequent stages, thus avoiding increasing the long-term burden on the linear power supply. When the control module 5 receives the "closing / opening" command, it immediately issues a boost enable signal: the DC-DC boost module 4 starts instantaneously, pumping the voltage at the supercapacitor terminals to the third DC voltage (typically 12V) required by the load switch with an efficiency of over 85%. The drive module 6 outputs a large current pulse at this voltage, directly driving the load switch coil to complete a reliable operation within ≤30ms. After the operation is completed, the control module 5 turns off the boost enable, the DC-DC boost module 4 stops working, and the system returns to its low-power normal state. If the power grid fails, the power failure detection unit 51 cuts off the boost enable within 10ms, and the farad capacitor only provides a μA-level sustaining current to the metering MCU, significantly extending the sleep time of the energy meter. This solves the problem that existing technologies cannot directly drive high-power load switches with low-power linear power supplies.

[0031] Furthermore, the linear power supply module 1 includes a power frequency transformer unit 11, a full-bridge rectifier unit 12, and a π-type filter unit 13; The power frequency transformer unit 11 is used to isolate and step down the 220V AC mains voltage to low voltage AC. The full-bridge rectifier unit 12 is used to rectify low-voltage AC into pulsating DC; The π-type filter unit 13 is used to suppress ripple and output a first DC voltage.

[0032] In this embodiment, the power frequency transformer unit 11 first isolates and steps down the 220V AC mains voltage to a low voltage (such as 15VAC), and then converts it into pulsating DC through the full-bridge rectifier unit 12; the π-type filter unit 13 (CLC structure) suppresses the 100Hz ripple to <100mVpp and outputs a stable first DC voltage (typically 20V).

[0033] Furthermore, the DC-DC buck module 2 includes a PWM controller unit 21, a power MOSFET unit 22, an energy storage inductor unit 23, an output capacitor unit 24, and a feedback voltage divider unit 25; The PWM controller unit 21 is used to generate a switching signal with an adjustable duty cycle; The power MOSFET unit 22 is used to perform high-frequency switching operations; The energy storage inductor unit 23 is used for energy storage and output smoothing; The output capacitor unit 24 is used to filter out high-frequency ripple; The feedback voltage divider unit 25 is used to sample the output voltage and feed it back to the PWM controller unit 21 to stabilize the second DC voltage.

[0034] In this embodiment, the PWM controller unit 21 generates an adjustable duty cycle (D≈0.42) to drive the power MOSFET unit 22 to switch at high frequency; the energy storage inductor unit 23 stores energy during the conduction period and freewheels during the turn-off period, forming an LC filter with the output capacitor unit 24; the feedback voltage divider unit 25 samples the output voltage in real time and sends it back to the PWM controller 21, and stabilizes the second DC voltage (5V±2%) in a closed loop.

[0035] Furthermore, the supercapacitor energy storage module 3 includes a supercapacitor unit 31, a current-limiting resistor unit 32, an anti-reverse diode unit 33, and a voltage equalizing resistor unit 34; The supercapacitor unit 31 is used for large-capacity energy storage with a second DC voltage. The current-limiting resistor unit 32 is used to charge the supercapacitor with the second DC voltage through a constant resistance method, thereby limiting the excessive current at the beginning of charging and preventing the DC-DC module from overcurrent protection. The anti-reverse diode unit 33 is used to prevent reverse discharge; The voltage equalization resistor unit 34 is used to maintain the long-term voltage balance between the individual cells when the two individual supercapacitors are used together.

[0036] In this embodiment, the current-limiting resistor unit 32 limits the charging current to within 0.5C to prevent surges; the anti-reverse diode unit 33 prevents the capacitor from discharging in reverse; and the voltage equalizing resistor unit 34 is connected in parallel across the series-connected supercapacitors to balance the leakage current and maintain long-term voltage balance.

[0037] Furthermore, the DC-DC boost module 4 includes a boost controller unit 41, a boost inductor unit 42, a synchronous rectifier MOSFET unit 43, an output rectifier diode unit 44, an adjustable feedback unit 45, and an output capacitor unit 46; The boost controller unit 41 is used to start boosting when triggered by the control module 5; The boost inductor unit 42 is used for energy storage and transmission; The synchronous rectifier MOSFET unit 43 is used to perform high-frequency switching operations; The output rectifier diode unit 44 is used to isolate the input and output terminals; The adjustable feedback unit 45 is used to set the third DC voltage by adjusting the voltage divider resistor; The output capacitor unit 46 is used to smooth the DC output after boosting.

[0038] In this embodiment, after receiving the enable signal, the boost controller unit 41 drives the boost inductor unit 42 to store energy at a fixed frequency (e.g., 500kHz); the synchronous rectifier MOSFET unit 43 and the output rectifier diode unit 44 work together to reduce conduction losses; the adjustable feedback unit 45 sets the third DC voltage (12V) through the voltage divider network; and the output capacitor unit 46 filters out high-frequency ripple.

[0039] Furthermore, the control module 5 includes a power failure detection unit 51, a boost enable unit 52, a timing logic unit 53, and a communication interface unit 54; The power failure detection unit 51 is used to monitor the grid voltage in real time and generate a power failure signal when power fails. The boost enable unit 52 is used to control the start and stop of the DC-DC boost module 4 according to the load switch action command or power failure signal. The timing logic unit 53 is used to coordinate the timing of supercapacitor charging, boost start-up, and drive signal issuance. The communication interface unit 54 is used to interact with the external main control MCU to exchange switch action commands and status information.

[0040] In this embodiment, the power failure detection unit 51 monitors the mains voltage in real time through a resistor divider and comparator, with the threshold set to 80% of the rated value; the boost enable unit 52 immediately pulls the EN pin of the chip high / low when the "action command" or "power failure signal" arrives; the timing logic unit 53 ensures that the supercapacitor is charged before the boost is started; and the communication interface unit 54 exchanges commands and status with the main control MCU.

[0041] Furthermore, the driving module 6 includes a driving chip unit 61, a gate resistor unit 62, an energy storage electrolysis unit 63, a protection TVS unit 64, and a current sampling unit 65; The driving chip unit 61 is used to output a large current driving pulse under the third DC voltage; The gate resistor unit 62 is used to suppress ringing and EMI; The energy storage electrolysis unit 63 is used to compensate for instantaneous current drops; The protection TVS unit 64 is used to absorb the reverse induced voltage of the load switch coil; The current sampling unit 65 is used to monitor the drive current in real time and feed back overcurrent information to the control module 5.

[0042] In this embodiment, the drive chip unit 61 outputs a large current pulse at 12V; the gate resistor unit 62 suppresses MOSFET ringing; the energy storage electrolysis unit 63 compensates for the instantaneous current drop in the coil; the protection TVS unit 64 absorbs the reverse induced voltage; and the current sampling unit 65 monitors overcurrent in real time and provides feedback.

[0043] Furthermore, the load switch module 7 includes a magnetic latching relay unit 71, an auxiliary contact unit 72, and an arc extinguishing unit 73; The magnetic latching relay unit 71 is used to achieve contact closure and retention under the action of driving current; The auxiliary contact unit 72 is used to provide feedback on the switch position signal; The arc-extinguishing unit 73 is used to suppress the electric arc during disconnection.

[0044] In this embodiment, the magnetic latching relay unit 71 is mechanically locked after being driven by a pulse current, and the coil does not need to be energized for a long time; the auxiliary contact unit 72 provides feedback on the actual switching state; and the arc extinguishing unit 73 (RC absorption or varistor) suppresses the interruption arc.

[0045] The circuit diagram of DCDC step-down module 2 is as follows: Figure 9 As shown in the diagram. Capacitor C2 is used for input filtering. R1 and R8 are connected in series for voltage division, enabling the control function of the chip's EN pin. C1 is the chip's bootstrap circuit, providing current for chip startup. L2 is the energy storage inductor, storing energy. R3 and R9 control the chip's output voltage, setting the output voltage value to be lower than the maximum withstand voltage of the supercapacitor. This circuit is used to charge the supercapacitor in the energy storage circuit. The energy storage circuit of supercapacitor energy storage module 3 consists of supercapacitor E1, with a typical capacitance of 1.5F / 5.5V. Diode D3 prevents reverse discharge of the supercapacitor. Resistors R2 and R6 are used for charging current limiting. Its structural diagram is shown below. Figure 10 As shown.

[0046] The DC-DC boost module 4 consists of a boost-type DC-DC regulator U2 and peripheral circuitry, and features enable control functionality. Its input terminal is connected to the positive terminal of a supercapacitor via a diode, and its output terminal is connected to a relay driver chip. By adjusting its feedback resistors R5 and R10, the regulator's output voltage is changed, thus obtaining the voltage required to drive the relay. Its structural diagram is shown below. Figure 11 As shown.

[0047] The voltage regulator U2 enable terminal is connected to the control unit. When the smart energy meter is powered off, the enable is turned off to reduce the energy consumption of the supercapacitor. When the smart energy meter is powered on, the enable is turned on to convert the supercapacitor energy into relay driving energy.

[0048] The circuit and load switch principle of drive module 6: The control circuit sends signals to the drive circuit to control the working state of the drive circuit, thereby controlling the operation of the load switch. UZ1 is a dedicated chip for motor drive, and its load capacity must meet the power requirements of the subsequent load switch. R11 and R12 are series resistors to reduce signal reflection and protect the chip's I / O lines. E3 is an electrolytic capacitor for energy storage, reducing voltage fluctuations during load switch operation and improving power supply stability. PK1 is a load switch drive protection device. Its structural diagram is shown below. Figure 12 As shown.

[0049] In summary, the circuit components are as follows. This invention can be implemented using the following example: Assume that in the prior art, the typical power of a load switch is 9W, and the operating time is ≤30ms. The energy required to drive the load switch to complete one operation is W1=PT=9W30ms=0.27J. The typical power of a linear transformer is around 3W. This is far from sufficient to drive the load switch. Therefore, the energy released by a supercapacitor is needed to drive the load switch. In existing applications, the withstand voltage of supercapacitors is generally low due to cost considerations; the high voltage required for operation must be obtained through a DC-DC boost converter. Assuming an 85% conversion efficiency, a Vmax voltage of 5V, and a Vmin voltage of 2.5V in the DC-DC boost circuit, and using the supercapacitor energy conversion formula W1=1 / 2C(Vmax²-Vmin²)*0.85, the supercapacitor capacitance required for one load switch operation is approximately: C≈0.034F. Assuming a 1.5F / 5.5V farad capacitor is selected, with a maximum voltage of 5V and a minimum voltage of 2.5V, the energy conversion formula for the farad capacitor shows that it can support approximately 44 normal operation of the load switch.

[0050] Please see Figure 13 Secondly, a load switch driving method based on a linear power supply of a smart energy meter, used in the load switch driving system based on a linear power supply of a smart energy meter as described in the first aspect, includes the following steps: S1: Linear power module 1 isolates and steps down the mains voltage to a first DC voltage; Specifically, the power frequency transformer unit 11 first isolates and steps down the 220V AC mains voltage to a low voltage AC of about 15V, then converts it into pulsating DC through the full-bridge rectifier unit 12, and finally suppresses the ripple to <100mVpp through the π-type filter unit 13 (CLC) to output a stable first DC voltage of 20V.

[0051] S2: DC-DC step-down module 2 reduces the first DC voltage to the second DC voltage and charges the farad capacitor energy storage module 3; Specifically, the PWM controller unit 21 drives the power MOSFET unit 22 at a fixed frequency of 1.6MHz, and forms a synchronous Buck topology with the energy storage inductor unit 23 and the output capacitor unit 24 to reduce 20V to 5V; the current limiting resistor unit 32 limits the initial charging current to 0.5C (about 0.75A), and the farad capacitor unit 31 charges to above 2.5V within <30s, which satisfies the load switch to perform a complete operation.

[0052] S3: When the control module 5 receives the load switch operation command, it enables the DC-DC boost module 4; Specifically, after the MCU receives the "close / open" command via UART, the timing logic unit 53 first confirms that the voltage of the supercapacitor is ≥4V, and then the boost enable unit 52 pulls up the EN pin of the boost chip to 5V, with the entire enable delay <2ms.

[0053] S4: DC-DC boost module 4 boosts the voltage of the supercapacitor to the third DC voltage and supplies power to drive module 6; Specifically, the boost controller unit 41 drives the boost inductor unit 42 and the synchronous rectification MOSFET unit 43 at 1.6MHz to pump 5V to 12V. The adjustable feedback unit 45 precisely sets the output through R5 / R10. The output capacitor unit 46 provides a transient current of >1A and a voltage drop of <5%.

[0054] S5: Drive module 6 uses the third DC voltage to drive load switch module 7 to complete the switching action; Specifically, the load switch driver chip unit 61 outputs a 2A peak current pulse under 12V power supply. After the ringing is suppressed by the gate resistor unit 62, it directly drives the magnetic latching relay coil. The protection TVS unit 64 clamps the coil reverse spike within 30V, and the action time is ≤30ms.

[0055] S6: When the power grid fails, the control module 5 shuts down the DC-DC boost module 4 to reduce the energy consumption of the supercapacitor; Specifically, when the power-down detection unit 51 detects that the input voltage is lower than 176V, it immediately pulls down the EN pin through the boost enable unit 52, and the DC-DC boost module 4 shuts down current <1µA; the farad capacitor provides µA-level leakage current only through the voltage equalization resistor unit 34 to maintain MCU sleep for ≥24h.

[0056] The beneficial effects of this invention are: The circuit is simple in composition and uses conventional components. It mainly utilizes the supercapacitors already used in smart energy meters to achieve the function of driving a high-power load switch with a low-power linear power supply. Therefore, it does not require changing the power supply design, resulting in a significant cost advantage. Because the circuit design is simpler than that of a switching power supply circuit, it greatly reduces the design difficulty of the product and further improves the reliability of the product in the field.

[0057] The above-disclosed embodiments are merely preferred embodiments of the load switch drive system and method based on the linear power supply of a smart energy meter according to the present invention. Of course, they should not be construed as limiting the scope of the present invention. Those skilled in the art can understand that all or part of the processes of the above embodiments can be implemented, and equivalent changes made in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A load switch drive system based on the linear power supply of a smart energy meter, characterized in that, It includes a linear power supply module, a DC-DC buck module, a supercapacitor energy storage module, a DC-DC boost module, a control module, a drive module, and a load switch module. The linear power supply module, the DC-DC buck module, the supercapacitor energy storage module, the DC-DC boost module, the drive module, and the load switch module are connected in sequence. The control module is connected to the DC-DC boost module and the drive module. The linear power supply module is used to isolate and step down the mains voltage and output a first DC voltage; The DC-DC step-down module is used to reduce the first DC voltage to the second DC voltage; The supercapacitor energy storage module is used to charge and store transient drive energy with a second DC voltage; The DC-DC boost module is used to boost the voltage of the supercapacitor to the third DC voltage required by the load switch when enabled; The control module is used to enable the DC-DC boost module before the load switch operates and to turn off the DC-DC boost module after the power grid fails to reduce static power consumption. The drive module is used to output drive current under the power supply of a third DC voltage; The load switch module is used to perform on / off actions based on the drive current.

2. The load switch drive system based on the linear power supply of a smart energy meter as described in claim 1, characterized in that, The linear power supply module includes a power frequency transformer unit, a full-bridge rectifier unit, and a π-type filter unit; The power frequency transformer unit is used to isolate and step down the 220V AC mains voltage to a low voltage AC. The full-bridge rectifier unit is used to rectify low-voltage AC into pulsating DC. The π-type filter unit is used to suppress ripple and output a first DC voltage.

3. The load switch drive system based on the linear power supply of a smart energy meter as described in claim 1, characterized in that, The DC-DC buck module includes a PWM controller unit, a power MOSFET unit, an energy storage inductor unit, an output capacitor unit, and a feedback voltage divider unit; The PWM controller unit is used to generate a switching signal with an adjustable duty cycle; The power MOSFET unit is used to perform high-frequency switching operations; The energy storage inductor unit is used for energy storage and output smoothing; The output capacitor unit is used to filter out high-frequency ripple; The feedback voltage divider unit is used to sample the output voltage and feed it back to the PWM controller unit to stabilize the second DC voltage.

4. The load switch drive system based on the linear power supply of a smart energy meter as described in claim 1, characterized in that, The supercapacitor energy storage module includes a supercapacitor unit, a current-limiting resistor unit, a reverse protection diode unit, and a voltage-equalizing resistor unit. The supercapacitor unit is used for large-capacity energy storage using a second DC voltage. The current-limiting resistor unit is used to charge the supercapacitor with the second DC voltage through a constant resistance method, limiting the excessive current at the beginning of charging to prevent the DC-DC module from overcurrent protection. The anti-reverse diode unit is used to prevent the supercapacitor from discharging in reverse to the DC-DC step-down module; The voltage equalization resistor unit is used to maintain the long-term voltage balance between the individual cells when the two individual supercapacitors are used together.

5. The load switch drive system based on the linear power supply of a smart energy meter as described in claim 1, characterized in that, The DC-DC boost module includes a boost controller unit, a boost inductor unit, a synchronous rectifier MOSFET unit, an output rectifier diode unit, an adjustable feedback unit, and an output capacitor unit; The boost controller unit is used to initiate boost voltage upon triggering by the control module; The boost inductor unit is used for energy storage and transmission; The synchronous rectifier MOSFET unit is used to perform high-frequency switching operations; The output rectifier diode unit is used to isolate the input and output terminals; The adjustable feedback unit is used to set the third DC voltage by adjusting the voltage divider resistor; The output capacitor unit is used to smooth the DC output after boosting.

6. The load switch drive system based on the linear power supply of a smart energy meter as described in claim 1, characterized in that, The control module includes a power failure detection unit, a boost enable unit, a timing logic unit, and a communication interface unit; The power failure detection unit is used to monitor the grid voltage in real time and generate a power failure signal when power fails. The boost enable unit is used to control the start and stop of the DC-DC boost module according to the load switch operation command or power failure signal; The timing logic unit is used to coordinate the timing of supercapacitor charging, boost startup, and drive signal issuance. The communication interface unit is used to interact with the external main control MCU to exchange switch action commands and status information.

7. A load switch driving method based on a linear power supply of a smart energy meter, used in the load switch driving system based on a linear power supply of a smart energy meter as described in any one of claims 1-6, characterized in that, Includes the following steps: The linear power module isolates and steps down the mains voltage to a first DC voltage; The DC-DC step-down module reduces the first DC voltage to the second DC voltage and charges the supercapacitor energy storage module. The control module enables the DC-DC boost module when it receives a load switch operation command; The DC-DC boost module boosts the voltage of the supercapacitor to a third DC voltage and supplies power to the drive module. The drive module uses a third DC voltage to drive the load switch module to complete the switching action; When the power grid fails, the control module shuts down the DC-DC boost module to reduce the energy consumption of the supercapacitor.

Images