Electric energy meter linear power supply with adjustable transient heavy load capability and wide power supply range

Abstract

The invention discloses an electric energy meter linear power supply with adjustable transient heavy load capacity and a wide power supply range, which comprises an alternating current step-down circuit, a main system power supply circuit and a relay driving circuit, and is characterized in that the output end VCC of the main system power supply circuit is used for supplying power to an electric energy meter system, and the relay driving circuit is used for driving a relay to act; the electric energy meter linear power supply with the adjustable transient heavy load capacity and the wide power supply range further comprises a transient heavy load power supply circuit. The output end of the alternating-current step-down circuit is connected with the input end of the transient heavy-load power supply circuit, and the output end VQL of the transient heavy-load power supply circuit is connected with the power supply end of the relay driving circuit. On the basis of a traditional linear power supply, a transient heavy load power supply circuit is additionally arranged to independently supply power to the relay driving circuit, and therefore the requirement for transient heavy load is met while the system power supply voltage is not increased and normal low power consumption is kept.

Description

Technical Field

[0001] The present invention belongs to the field of linear power supplies, and particularly relates to a linear power supply for an electric energy meter. Background Art

[0002] With the popularization of high-power household appliances and the significant increase in the power consumption per unit in modern families, the measured current load of electric energy meters during peak electricity consumption periods has generally exceeded 100A. To ensure metering accuracy and electrical safety, the power grid has carried out three important upgrades to smart electric energy meters: First, the rated current of the load switch has been increased from 60A to 100A to adapt to higher current demands; second, the safety distance between the moving and static contacts has been extended from 2mm to 5.5mm to enhance safety during power-off; at the same time, the short-circuit withstand capacity of the built-in switch has been significantly improved, enabling it to reliably withstand a short-circuit current impact of 3000A, 10ms, and meet higher short-time working withstand requirements.

[0003] However, the above improvements directly result in the power consumption of the driving coil of the relay increasing from 1.5W to 9W to meet the breaking requirements of the new load switch. If a traditional linear power supply scheme is adopted, it is necessary to increase the output voltage of the transformer to improve the load-carrying capacity. However, directly increasing the output voltage will bring the following problems: First, the overall power consumption increases significantly, reducing the system efficiency; second, when the input voltage is 1.9 times the rated voltage, the output DC voltage may exceed the maximum withstand voltage of the subsequent circuit, resulting in circuit damage; in addition, since the system power supply and transient heavy load (the instantaneous high-power load required by the relay driving coil when breaking the load switch) share a power supply circuit, system power supply drops are likely to occur during the drive of the transient heavy load, causing abnormal system operation.

[0004] On the other hand, electric energy meters need to work in a complex voltage environment, and there may be problems of relatively high and low voltages. Existing linear power supplies do not have the ability to carry a transient high-power load under a wide input power supply range.

[0005] Since the traditional linear power supply scheme cannot meet the requirements of wide input power supply range, normal low power consumption, and transient heavy load carrying, existing electric energy meters usually use a switching power supply to solve the above problems. However, the switching power supply scheme has problems such as increased cost, increased failure rate, and degraded EMI performance. In addition, the switching power supply scheme also has problems such as excessive starting current, resulting in the abnormal operation of the electric energy meter calibration bench. Summary of the Invention

[0006] The present invention proposes a linear power supply for an electric energy meter with adjustable transient heavy load capacity and a wide power supply range, and its purpose is to solve the problem that a linear power supply cannot simultaneously meet the requirements of wide input power supply range, normal low power consumption, and transient heavy load carrying.

[0007] The technical solution of the present invention is as follows: A linear power supply for an electric energy meter with adjustable transient overload capacity and wide power supply range, comprising an AC step-down circuit, a main system power supply circuit, and a relay drive circuit. The output end of the AC step-down circuit is connected to the input end of the main system power supply circuit. The output end VCC of the main system power supply circuit is used to supply power to the electric energy meter system. The relay drive circuit is used to drive the relay to act. The linear power supply for the electric energy meter with adjustable transient overload capacity and wide power supply range further comprises a transient overload power supply circuit; The output end of the AC step-down circuit is connected to the input end of the transient overload power supply circuit, and the output end V_QL of the transient overload power supply circuit is connected to the power supply end of the relay drive circuit.

[0008] As a further improvement of the linear power supply for the electric energy meter with adjustable transient overload capacity and wide power supply range: The transient overload power supply circuit includes a voltage multiplier circuit, a clamping voltage stabilizing circuit, and an energy storage circuit. The output end of the AC step-down circuit is connected to the input end of the voltage multiplier circuit. The output end of the voltage multiplier circuit is connected to the input end of the clamping voltage stabilizing circuit. The output end of the clamping voltage stabilizing circuit is connected to the energy storage circuit; The voltage multiplier circuit is used to increase the voltage. The clamping voltage stabilizing circuit is used to clamp the output overload power supply voltage and protect the backend circuit. The energy storage circuit is used to store electrical energy to meet the power supply requirements of the relay drive circuit.

[0009] As a further improvement of the linear power supply for the electric energy meter with adjustable transient overload capacity and wide power supply range: The voltage multiplier circuit includes capacitor C5, diode V3, diode V2, diode V6, and diode V8; The first AC output end AC-1 of the AC step-down circuit is connected to one end of capacitor C5 and at the same time to the positive electrode of diode V2; the negative electrode of diode V2 is connected to the other end of capacitor C5 and at the same time to the positive electrode of diode V3. The negative electrode of diode V3 is the output end of the voltage multiplier circuit; The second AC output end AC-2 of the AC step-down circuit is connected to the positive electrode of diode V6 and at the same time to the negative electrode of diode V8; the negative electrode of diode V6 is connected to the negative electrode of diode V2; the positive electrode of diode V8 is grounded.

[0010] As a further improvement of the linear power supply for the electric energy meter with adjustable transient overload capacity and wide power supply range: The clamping voltage stabilizing circuit includes a switching element and a switching drive control circuit. The input end of the clamping voltage stabilizing circuit is connected to the output end of the clamping voltage stabilizing circuit through the switching element. The switching drive control circuit is used to achieve the clamping of the output voltage of the switching element.

[0011] As a further improvement to the linear power supply of the electricity meter with adjustable transient overload capacity and wide power supply range: The switching element is an N-MOS transistor V4. The drain of the N-MOS transistor V4 is connected to the input terminal V_IN of the clamping voltage stabilizing circuit, and the source is connected to the output terminal of the clamping voltage stabilizing circuit. The input terminal V_IN of the clamping voltage stabilizing circuit is also grounded through a series-connected resistor R1 and capacitor C6 in sequence. The connection node between the resistor R1 and the capacitor C6 is connected to one end of the resistor R2, and the other end of the resistor R2 is connected to the gate of the N-MOS transistor V4.

[0012] As a further improvement to the linear power supply of the electricity meter with adjustable transient overload capacity and wide power supply range: The switching drive control circuit includes a zener diode V7. The positive electrode of the zener diode V7 is grounded, and the negative electrode is connected to one end of the resistor R2.

[0013] As a further improvement to the linear power supply of the electricity meter with adjustable transient overload capacity and wide power supply range: The switching drive control circuit includes a three-terminal adjustable voltage regulator D2, a resistor R4, and a resistor R5. The positive electrode of the three-terminal adjustable voltage regulator D2 is grounded, and the negative electrode is connected to one end of the resistor R2. The resistor R4 and the resistor R5 are connected in series between the source of the N-MOS transistor V4 and the ground terminal, and the connection node between the resistor R4 and the resistor R5 is connected to the reference terminal of the three-terminal adjustable voltage regulator D2.

[0014] As a further improvement to the linear power supply of the electricity meter with adjustable transient overload capacity and wide power supply range: A TVS tube V5 is connected between the gate and the source of the N-MOS transistor V4.

[0015] As a further improvement to the linear power supply of the electricity meter with adjustable transient overload capacity and wide power supply range: The switching element is a MOS transistor or a triode.

[0016] As a further improvement to the linear power supply of the electricity meter with adjustable transient overload capacity and wide power supply range: The energy storage circuit includes an energy storage capacitor C7 and a resistor R3 connected in parallel between the output terminal and the ground terminal. The output terminal of the clamping voltage stabilizing circuit is directly connected to the output terminal of the energy storage circuit, which is the output terminal V_QL of the transient overload power supply circuit.

[0017] Compared with the prior art, the present invention has the following positive effects: 1. Based on the traditional linear power supply, the present invention adds a transient overload power supply circuit to independently supply power to the relay drive circuit. The transient overload power supply circuit increases the voltage through a voltage doubling circuit, and at the same time, the energy storage circuit stores energy, so as to meet the demand of transient overload while not increasing the system power supply voltage and maintaining low power consumption in the normal state.

[0018] 2. The transient overload power supply circuit boosts the voltage through a voltage multiplier circuit and clamps the output voltage through a clamping voltage stabilization circuit, enabling it to obtain a wide power supply range (170V~420V@AC), thus ensuring that the system input power supply can still meet the requirements of transient overload under a wide power supply range.

[0019] 3. By adjusting the switching drive control circuit of the clamping voltage stabilization circuit (for example, selecting zener diodes with different voltage stabilization values), the voltage value of the output terminal V_QL can be adjusted, and further the transient overload capacity can be adjusted.

[0020] 4. Compared with the switching power supply scheme, the circuit of the present invention is relatively simple, has higher reliability, and has cost advantages. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is the circuit schematic diagram of the AC step-down circuit, the main system power supply circuit, and the transient overload power supply circuit in the linear power supply in Embodiment 1; Figure 2 It is the circuit schematic diagram of the relay drive circuit in Embodiment 1; Figure 3 It is the circuit schematic diagram of the clamping voltage stabilization circuit in Embodiment 2.

[0022] In the figure, part A is the AC step-down circuit, part B is the main system power supply circuit, part C is the transient overload power supply circuit, part D is the relay drive circuit, part C-1 is the voltage multiplier circuit, C-2-A is the clamping voltage stabilization circuit in Embodiment 1, C-2-B is the clamping voltage stabilization circuit in Embodiment 2, and C-3 is the energy storage circuit. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The technical solution of the present invention will be described in detail below with reference to the drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Embodiment 1

[0024] As Figure 1 , a linear power supply for an electric energy meter with adjustable transient overload capacity and a wide power supply range includes an AC step-down circuit, a main system power supply circuit, a transient overload power supply circuit, and a relay drive circuit.

[0025] The output terminal of the AC step-down circuit is connected to the input terminal of the main system power supply circuit, and the output terminal VCC of the main system power supply circuit is used to supply power to the electric energy meter system.

[0026] The output terminal of the AC step-down circuit is connected to the input terminal of the transient overload power supply circuit, the output terminal V_QL of the transient overload power supply circuit is connected to the power supply terminal of the relay drive circuit, and the relay drive circuit is used to drive the relay to act.

[0027] Based on the traditional linear power supply, the present invention adds a transient heavy-load power supply circuit to supply power to the relay drive circuit alone, meeting the power supply requirements of transient heavy loads, and at the same time not increasing the system power supply voltage, enabling the system to maintain low power consumption in the normal state.

[0028] 1. AC step-down circuit A: The AC voltage is input at the AC step-down circuit end. After passing through protection devices (varistor RV1, thermistor RT1), the voltage transformation is completed through the linear transformer T1, and low-voltage alternating current is output for the use of the subsequent circuit.

[0029] The normal operation power consumption of the electricity meter and terminal equipment is relatively low, and the linear transformer selected at the front end is usually a small-power transformer.

[0030] 2. Main system power supply circuit B: The input low-voltage alternating current is converted into direct current V_DC by the full-bridge rectifier chip V1, then filtered by the input filter capacitors C1 and C2 and input to the linear voltage regulator D1 to obtain the DC power supply V_DC, and then output the stable DC power supply VCC after passing through the filter capacitors C3 and C4 for the use of the system MCU and peripherals. To ensure the power efficiency of the whole machine, the input voltage V_DC of D1 should not be too high.

[0031] 3. Transient heavy-load power supply circuit C: The transient heavy-load power supply circuit includes a voltage multiplier circuit, a clamping and voltage stabilizing circuit, and an energy storage circuit. The output end of the AC step-down circuit is connected to the input end of the voltage multiplier circuit, the output end of the voltage multiplier circuit is connected to the input end of the clamping and voltage stabilizing circuit, and the output end of the clamping and voltage stabilizing circuit is connected to the energy storage circuit.

[0032] Among them, the voltage multiplier circuit is used to increase the voltage, the clamping and voltage stabilizing circuit is used to clamp the output heavy-load power supply voltage and protect the subsequent circuit, and the energy storage circuit is used to store electrical energy to meet the power supply requirements of the relay drive circuit.

[0033] Among them: 3-1. The voltage multiplier circuit includes capacitor C5, diode V3, diode V2, diode V6, and diode V8.

[0034] The first AC output end AC-1 of the AC step-down circuit is connected to one end of capacitor C5 and also to the positive electrode of diode V2; the negative electrode of diode V2 is connected to the other end of capacitor C5 and also to the positive electrode of diode V3, and the negative electrode of diode V3 is the output end of the voltage multiplier circuit. The second AC output end AC-2 of the AC step-down circuit is connected to the positive electrode of diode V6 and also to the negative electrode of diode V8; the negative electrode of diode V6 is connected to the negative electrode of diode V2; the positive electrode of diode V8 is grounded.

[0035] The voltage between AC-1 and AC-2 is alternating current. When the voltage of AC-2 is greater than that of AC-1, the diode V6 conducts forward to charge the electrolytic capacitor C5. At the initial stage of system cold start and during driving transient heavy load, when V_IN is lower than V_M, V3 also conducts forward. When the voltage of AC-1 is greater than that of AC-2, due to the fact that the voltage across the capacitor cannot change suddenly, the electrolytic capacitor C5 and the secondary coil of the transformer jointly charge the backend energy storage circuit through the diode V3 and the clamping voltage stabilization circuit. At the initial stage of system cold start, since the capacitance of the backend energy storage circuit is much larger than that of the electrolytic capacitor C5, after the electrolytic capacitor C5 is completely discharged, the voltage of V_M may still be lower than AC-1. Therefore, there is a working condition of reverse charging for the electrolytic capacitor C5. Thus, a diode V2 is connected in parallel across C5 to limit the reverse voltage of C5, restricting the maximum value of the reverse voltage of C5 to the forward voltage drop of V2 to prevent the electrolytic capacitor C5 from being damaged due to excessive reverse voltage. When the voltage doubling circuit charges the subsequent circuit, if the diode V8 is not used, a return path can be formed by means of the diode inside the rectifying full-bridge rectifier chip V1. However, considering that the current-carrying capacity of the internal diode of V1 is usually small, the return diode V8 is added.

[0036] 3-2. The clamping voltage stabilization circuit includes a switching element and a switching drive control circuit. The input end of the clamping voltage stabilization circuit is connected to the output end of the clamping voltage stabilization circuit through the switching element, and the switching drive control circuit is used to achieve the clamping of the output voltage of the switching element.

[0037] In this embodiment, the switching element is an N-MOS transistor V4. The drain of the N-MOS transistor V4 is connected to the input end V_IN of the clamping voltage stabilization circuit, and the source is connected to the output end of the clamping voltage stabilization circuit. The input end V_IN of the clamping voltage stabilization circuit is also grounded through a series-connected resistor R1 and capacitor C6 in sequence. The connection node between the resistor R1 and the capacitor C6 is connected to one end of the resistor R2, and the other end of the resistor R2 is connected to the gate of the N-MOS transistor V4.

[0038] The switching drive control circuit includes a zener diode V7. The positive electrode of the zener diode V7 is grounded, and the negative electrode is connected to one end of the resistor R2.

[0039] The resistor R1 and the capacitor C6 form an RC charging circuit, which can control the slow turn-on of the N-MOS transistor V4 to prevent the excessive instantaneous impact of the backend load on the power supply. At the same time, the resistor R1 is used as the pull-up resistor for the gate of the N-MOS transistor, providing a control voltage for the turn-on of the N-MOS transistor V4. The resistor R2 is a current-limiting protection resistor to prevent the N-MOS transistor V4 from oscillating. The zener diode V7 is used to clamp the gate voltage of the switching transistor. The condition for the N-MOS transistor V4 to turn on is that the difference between its gate voltage and source voltage reaches a certain threshold VGS(TH). Therefore, after the capacitor C7 is fully charged, the voltage value of V_QL is the zener voltage Vz of the zener diode V7 minus the VGS(TH) (about 1.5V) of the N-MOS transistor. The voltage value of V_QL can be adjusted by selecting zener diodes with different zener voltages, thereby adjusting the transient heavy-load capacity. To prevent the excessive voltage difference between the gate and source of the N-MOS transistor V4, causing overvoltage damage, a TVS diode V5 is connected in parallel with the N-MOS transistor V4 for protection.

[0040] In the initial stage of the system cold start, due to the large capacitance of the capacitor in the backend energy storage circuit, the charging current of the linear transformer to the backend capacitor through the clamping voltage stabilization circuit is large. It should be noted that when the charging current is too large, the excessive power dissipation on V4 may cause it to burn out. Therefore, when selecting V4, the required specification model should be selected according to the maximum power dissipation measured in actual tests.

[0041] As an optional implementation, when the load power is small, an NPN transistor can also be used to replace the N-MOS transistor V4.

[0042] 3-3. The energy storage circuit includes an energy storage capacitor C7 and a resistor R3 connected in parallel between the output terminal and the ground terminal. The output terminal of the clamping voltage stabilization circuit is directly connected to the output terminal of the energy storage circuit, which is the output terminal V_QL of the transient heavy-load power supply circuit.

[0043] To ensure that the instantaneous large energy required by the internal drive coil of the high-power relay (assuming its parameters are rated power 9W, rated voltage 12V, and drive time 50mS) is satisfied, the capacitance selection of the corresponding electrolytic capacitor C7 is generally large (such as ≥3000μF). At the same time, a relatively high working voltage V_QL (such as 27V - 30V) needs to be provided to ensure that the voltage across the electrolytic capacitor C7 is not lower than the minimum value of the relay drive voltage within the typical 50mS time of the MCU controlling the drive of the relay. The electrolytic capacitor C7 is the main energy storage device. When the voltage across C7 starts to decrease during the operation of driving the relay, the alternating current from the AC step-down circuit and the direct current stored in the voltage doubler circuit will jointly replenish the energy of the energy storage circuit through the clamping voltage stabilization circuit, jointly supporting the MCU to control the relay to complete the switching-on and switching-off actions. The resistor R3 in the circuit is a discharge resistor to ensure that the electrolytic capacitor C7 is discharged after the system loses power.

[0044] To ensure normal driving of transient heavy loads even in low-temperature environments, appropriate margins should be left when selecting the regulated voltage value Vz of the voltage-regulating diode V7 and the capacitance of the energy-storage electrolytic capacitor C7.

[0045] 4. Relay driving circuit D: As Figure 2 , the main device of the relay driving circuit is the relay driving chip D3 (common models: 8251S, PN7705, BL5616). The power supply terminal of the relay driving chip D3 is connected to the output terminal V_QL of the energy-storage circuit, and the control pin is connected to the I / O ports (RelayOff, RelayOn) of the system MCU. The MCU can achieve relay tripping / closing actions by controlling the control pin of the relay driving chip D3. Resistors R6 and R7 are pull-down resistors for the control signal to ensure that the relay driving chip does not malfunction when the I / O state is uncontrollable during the initial power-on startup of the MCU. Resistor R8 is a resistor for setting the relay driving current-limiting parameter, which can adjust the maximum output current limit value of the relay driving chip D3.

[0046] The energy required to drive the transient heavy load mainly comes from the electrolytic capacitor C7. As the relay driving chip D3 starts to conduct, the voltage V_QL of the electrolytic capacitor C7 gradually decreases, and the driving ability gradually decreases. Therefore, this solution cannot be directly used to drive heavy loads that require constant-voltage driving. In this case, a voltage-regulating circuit can be added at the back end to meet the requirements of constant-voltage driving. Embodiment 2

[0047] The difference between this embodiment and Embodiment 1 lies in the different structure of the switch driving control circuit.

[0048] Specifically, as Figure 3 , the switch driving control circuit includes a three-terminal adjustable voltage regulator D2, a resistor R4, and a resistor R5. The positive pole of the three-terminal adjustable voltage regulator D2 is grounded, the negative pole is connected to one end of the resistor R2, and the resistor R4 and the resistor R5 are connected in series between the source electrode of the N-MOS transistor V4 and the ground terminal. The connection node between the resistor R4 and the resistor R5 is connected to the reference terminal of the three-terminal adjustable voltage regulator D2.

[0049] Due to the relatively large accuracy and temperature coefficient of the voltage-regulating diode, when a more accurate clamping voltage is required, this embodiment can be used, and the 431 chip (three-terminal adjustable voltage regulator D2) and the feedback resistors R4 and R5 are used to replace V7.

[0050] It should be noted that for those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. The scope of the present invention is defined by the claims rather than the above description.

Claims

1. A linear power supply for an electric energy meter with adjustable transient heavy load capacity and a wide power supply range, comprising an AC step-down circuit, a main system power supply circuit and a relay drive circuit, wherein the output end of the AC step-down circuit is connected to the input end of the main system power supply circuit, the output end VCC of the main system power supply circuit is used to power the electric energy meter system, and the relay drive circuit is used to drive the relay to operate, characterized in that: The electric energy meter linear power supply with adjustable transient heavy load capacity and wide power supply range also includes a transient heavy load power supply circuit; The output end of the AC step-down circuit is connected to the input end of the transient heavy load power supply circuit, and the output end V_QL of the transient heavy load power supply circuit is connected to the power supply end of the relay drive circuit.

2. The linear power supply for electric energy meter with adjustable transient heavy load capacity and wide power supply range as claimed in claim 1, characterized in that: The transient heavy load power supply circuit includes a voltage doubler circuit, a clamping voltage stabilizing circuit and an energy storage circuit, the output end of the AC step-down circuit is connected to the input end of the voltage doubler circuit, the output end of the voltage doubler circuit is connected to the input end of the clamping voltage stabilizing circuit, and the output end of the clamping voltage stabilizing circuit is connected to the energy storage circuit; The voltage doubling circuit is used to increase the voltage, the clamping voltage stabilizing circuit is used to clamp the output heavy-load power supply voltage and protect the back-end circuit, and the energy storage circuit is used to store electrical energy to meet the power supply requirements of the relay drive circuit.

3. The linear power supply for electric energy meter with adjustable transient heavy load capacity and wide power supply range as claimed in claim 2, characterized in that: The voltage doubler circuit includes capacitor C5, diode V3, diode V2, diode V6 and diode V8; The first AC output terminal AC-1 of the AC step-down circuit is connected to one end of the capacitor C5 and to the positive electrode of the diode V2; the negative electrode of the diode V2 is connected to the other end of the capacitor C5 and to the positive electrode of the diode V3, and the negative electrode of the diode V3 is the output end of the voltage doubler circuit; The second AC output terminal AC-2 of the AC step-down circuit is connected to the anode of the diode V6 and also connected to the cathode of the diode V8; the cathode of the diode V6 is connected to the cathode of the diode V2; the anode of the diode V8 is grounded.

4. The linear power supply for electric energy meter with adjustable transient heavy load capacity and wide power supply range as claimed in claim 2, characterized in that: The clamping voltage stabilizing circuit comprises a switch element and a switch driving control circuit, wherein the input end of the clamping voltage stabilizing circuit is connected to the output end of the clamping voltage stabilizing circuit through the switch element, and the switch driving control circuit is used to realize the clamping of the output voltage of the switch element.

5. The linear power supply for electric energy meter with adjustable transient heavy load capacity and wide power supply range as claimed in claim 4, characterized in that: The switch element is an N-MOS tube V4, the drain of the N-MOS tube V4 is connected to the input end V_IN of the clamping voltage stabilizing circuit, and the source is connected to the output end of the clamping voltage stabilizing circuit; the input end V_IN of the clamping voltage stabilizing circuit is also grounded through a resistor R1 and a capacitor C6 connected in series in sequence, the connection node between the resistor R1 and the capacitor C6 is connected to one end of the resistor R2, and the other end of the resistor R2 is connected to the gate of the N-MOS tube V4.

6. The linear power supply for electric energy meter with adjustable transient heavy load capacity and wide power supply range as claimed in claim 5, characterized in that: The switch drive control circuit includes a voltage stabilizing diode V7, wherein the positive electrode of the voltage stabilizing diode V7 is grounded, and the negative electrode is connected to one end of the resistor R2.

7. The linear power supply for electric energy meter with adjustable transient heavy load capacity and wide power supply range as claimed in claim 5, characterized in that: The switch drive control circuit includes a three-terminal adjustable voltage regulator D2, a resistor R4 and a resistor R5. The positive electrode of the three-terminal adjustable voltage regulator D2 is grounded, and the negative electrode is connected to one end of the resistor R2. The resistor R4 and the resistor R5 are connected in series between the source electrode of the N-MOS tube V4 and the ground terminal, and the connection node between the resistor R4 and the resistor R5 is connected to the reference terminal of the three-terminal adjustable voltage regulator D2.

8. The linear power supply for electric energy meter with adjustable transient heavy load capacity and wide power supply range as claimed in claim 5, characterized in that: A TVS tube V5 is connected between the gate and source of the N-MOS tube V4.

9. The linear power supply for electric energy meter with adjustable transient heavy load capacity and wide power supply range as claimed in claim 4, characterized in that: The switch element is a MOS tube or a triode.

10. The linear power supply for electric energy meter with adjustable transient heavy load capacity and wide power supply range as claimed in claim 2, characterized in that: The energy storage circuit includes an energy storage capacitor C7 and a resistor R3 connected in parallel between the output terminal and the ground terminal. The output terminal of the clamping voltage stabilizing circuit is directly connected to the output terminal of the energy storage circuit, which is the output terminal V_QL of the transient heavy load power supply circuit.

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