Electric energy meter and voltage reference diode power supply circuit

Abstract

The utility model relates to an electric energy meter and a voltage reference diode power supply circuit and belongs to the technical field of electric energy meters. According to the utility model, the voltage bootstrap circuit and the temperature compensation circuit are added in the existing power supply circuit, a stable power supply is provided for the voltage reference diode through the voltage bootstrap circuit, and the output drift of the voltage reference diode caused by temperature change is corrected through the temperature compensation circuit; the change of the voltage output value caused by the change of the working current of the voltage reference diode due to the change of the environment temperature is compensated, so that the problem that the voltage reference diode cannot meet the requirements of the electric energy meter due to the fluctuation of the output voltage is solved.

Description

Technical Field

[0001] This utility model relates to an energy meter and a voltage reference diode power supply circuit, belonging to the field of energy meter technology. Background Technology

[0002] The 0.01-class standard energy meter serves as the standard instrument for energy meter traceability. Its voltage and current sampling circuits are converted into digital signals by an ADC (analog-to-digital converter). The subsequent signal processing section runs an energy metering algorithm to obtain energy-related data and information. The sampling accuracy of the standard energy meter's ADC depends on the reference voltage source that provides the quantization comparison benchmark. The accuracy and stability of the reference voltage source play a decisive role in the overall accuracy and stability of the 0.01-class standard energy meter.

[0003] The reference voltage source circuit of existing standard energy meters, such as Figure 1 As shown, VSS is the DC power supply, and Z1 is the voltage reference diode. Its working principle is as follows: the input DC power supply VSS is converted into a stable DC voltage by a low-noise, high-PSRR linear regulated power supply (LDO). This voltage is then applied to the voltage reference diode Z1 after passing through resistor R1. When the voltage reference diode Z1 operates in the reverse breakdown region, its voltage is a stable value that remains essentially unchanged with temperature. This voltage serves as the reference voltage for the ADC conversion circuit in the energy meter. However, when the ambient temperature changes, the output voltage of the LDO and the resistance of R1 will change, causing a change in the operating current of Z1. For example, when the operating current changes by 1 microamp, the regulated output value of Z1 changes by ΔV = 1 μA * the dynamic impedance of Z1. If the grid impedance of Z1 is 10 ohms, in a 0.01-level high-precision standard energy meter, this output voltage fluctuation does not meet the performance requirements, and therefore cannot meet the needs of the energy meter. Utility Model Content

[0004] The purpose of this invention is to provide a power supply circuit for an energy meter and a voltage reference diode, so as to solve the problem that the current voltage reference diode cannot meet the needs of the energy meter due to output voltage fluctuations.

[0005] This utility model provides a voltage reference diode power supply circuit to solve the above-mentioned technical problems. It includes a voltage source regulator circuit for providing a stable voltage, a voltage bootstrap circuit, and a temperature compensation circuit. The voltage bootstrap circuit includes an operational amplifier. The second input terminal of the operational amplifier is connected to the temperature compensation circuit, the first input terminal of the operational amplifier is connected to the output terminal of the voltage source regulator circuit, the output terminal of the operational amplifier is connected to the voltage reference diode through a first resistor, the first input terminal of the operational amplifier is also used to connect to the voltage reference diode, and the second input terminal of the operational amplifier is also connected between the output terminal of the operational amplifier and the first resistor.

[0006] Further, the temperature compensation circuit comprises a thermistor and a second resistor in parallel, one end of the thermistor and the second resistor in parallel is grounded, and the other end is connected with the second input end of the amplifier.

[0007] Further, a voltage stabilizing tube is arranged between the first input end of the operational amplifier and the output end of the voltage source stabilizing circuit.

[0008] Further, a third resistor is connected between the voltage stabilizing tube and the first input end of the operational amplifier.

[0009] Further, the first input end is a non-inverting input end, and the second input end is an inverting input end.

[0010] The utility model further provides a kind of electric energy meter, including voltage reference diode and the voltage reference diode power supply circuit for being used to power voltage reference diode, the voltage reference diode power supply circuit includes voltage source stabilizing circuit, voltage bootstrap circuit and temperature compensation circuit, the voltage bootstrap circuit includes operational amplifier, the second input end of operational amplifier is connected with temperature compensation circuit, the first input end of operational amplifier is connected with the output end of voltage source stabilizing circuit, the output end of operational amplifier is used for being connected to voltage reference diode by first resistance, the first input end of operational amplifier is also used to connect voltage reference diode, the second input end of operational amplifier is also connected to the output end of operational amplifier and first resistance between.

[0011] Further, the temperature compensation circuit comprises a thermistor and a second resistor in parallel, one end of the thermistor and the second resistor in parallel is grounded, and the other end is connected with the second input end of the amplifier.

[0012] Further, a voltage stabilizing tube is arranged between the first input end of the operational amplifier and the output end of the voltage source stabilizing circuit.

[0013] Further, a third resistor is connected between the voltage stabilizing tube and the first input end of the operational amplifier.

[0014] Further, the first input end is a non-inverting input end, and the second input end is an inverting input end.

[0015] The beneficial effects of this utility model are as follows: As an improved invention, this utility model adds a voltage bootstrap circuit and a temperature compensation circuit to the existing power supply circuit. The voltage bootstrap circuit provides a stable power supply to the voltage reference diode, and the temperature compensation circuit corrects the output drift of the voltage reference diode caused by temperature changes. It also compensates for the changes in voltage output value caused by changes in the operating current of the voltage reference diode due to changes in ambient temperature, thereby solving the problem that the voltage reference diode does not meet the requirements of the energy meter due to output voltage fluctuations. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of an existing voltage reference diode power supply circuit;

[0017] Figure 2 This is a schematic diagram of the power supply circuit for the voltage reference diode of this utility model. Detailed Implementation

[0018] The specific embodiments of this utility model will be further described below with reference to the accompanying drawings.

[0019] This invention employs a voltage bootstrap method to provide a stable voltage output to the voltage reference diode and adds a temperature compensation voltage to compensate for the changes in voltage output caused by changes in the operating current of the voltage reference diode due to changes in ambient temperature. This solves the problem that the voltage reference diode fails to meet the requirements of the energy meter due to output voltage fluctuations.

[0020] Example of a voltage reference diode power supply circuit

[0021] The voltage reference diode power supply circuit of this utility model is as follows: Figure 2 As shown, it includes a voltage source regulator circuit, a voltage bootstrap circuit, and a temperature compensation circuit. The voltage bootstrap circuit includes an operational amplifier. The second input terminal of the operational amplifier is connected to the temperature compensation circuit, and the first input terminal of the operational amplifier is connected to the output terminal of the voltage source regulator circuit. The output terminal of the operational amplifier is connected to the cathode of a voltage reference diode through a first resistor. The first input terminal of the operational amplifier is also used to connect to the voltage reference diode, and the second input terminal of the operational amplifier is also connected between the output terminal of the operational amplifier and the first resistor.

[0022] Specifically, the voltage source regulator circuit uses a low-noise, high-PSRR linear regulated power supply (LDO). The DC power supply VSS is converted into a stable DC voltage by the LDO. This DC voltage is applied to the voltage reference diode Z1 through the voltage bootstrap circuit, providing normal operating current for the voltage reference diode Z1. The voltage bootstrap circuit uses operational amplifier U1. The non-inverting input of operational amplifier U1 is connected to the output of the LDO via resistor R1 and Zener diode Z2. Simultaneously, the non-inverting input of operational amplifier U1 is also connected to the cathode of voltage reference diode Z1. A temperature compensation circuit is connected to the inverting input of operational amplifier U1. This temperature compensation circuit includes a parallel resistor R2 and a thermistor NTC (using a negative temperature coefficient). One end of the parallel connection between resistor R2 and the thermistor NTC is grounded, and the other end is connected to the inverting input of operational amplifier U1. The inverting input of operational amplifier U1 is also connected to the output of operational amplifier U1 via resistor R4, forming a negative feedback circuit for the operational amplifier. The output of operational amplifier U1 is connected to the cathode of voltage reference diode Z1 via resistor R3. The anode of voltage reference diode Z1 is grounded, and the voltage V across voltage reference diode Z1 is... RFE It refers to stabilizing the voltage. In this embodiment, the voltage reference diode Z1 is a Zener voltage reference diode, which can output a stable voltage value when operating in the reverse breakdown region.

[0023] The working principle of the voltage reference diode power supply circuit is as follows: When powered on normally, the output voltage of the LDO is V1. After passing through the Zener diode Z2 and the resistor R1, the voltage of V1 drops to V1-Vz2-VR1. That is, at this time, the voltage at the non-inverting input terminal of the operational amplifier U1 is V1-Vz2-VR1, and the voltage of the voltage reference diode Z1 is also V1-Vz2-VR1, where Vz2 is the Zener voltage of the Zener diode Z2, and VR1 is the voltage drop across the resistor R1.

[0024] After the power supply is powered on, when the voltage of the voltage reference diode Z1 has not reached its breakdown voltage value, the current flowing through the resistor R1 is relatively small, that is, the voltage drop across R1 can be ignored, and the voltage across the voltage reference diode Z1 is V1 - Vz2. If the voltage reaches the breakdown voltage value of the voltage reference diode Z1, the voltage reference diode Z1 enters the breakdown working area. At this time, the current flowing through the voltage reference diode Z1 increases, the current flowing through R1 also increases, and the voltage drop across R1 also increases. By setting the resistance value of the resistor R1, it can be made that V1 - VR1 < Vz2. In this way, the voltage regulator diode Z2 is in the cut-off area, and at this time, the output voltage of the LDO is disconnected from the subsequent stage. In this way, the voltage value VREF of the voltage reference diode Z1 is input to the non-inverting input terminal of the operational amplifier U1. The output voltage of the operational amplifier U1 is applied to both ends of the voltage reference diode Z1 after passing through R3, that is, the output of U1 provides a power supply input for the voltage reference diode Z1 after passing through R3. The output of the operational amplifier U1 forms a negative feedback loop through R4, resistor R2, and the thermistor NTC, and the output of the operational amplifier U1 and the output VREF of the voltage reference diode Z1 form a positive feedback loop. The negative feedback loop and the positive feedback loop act together on the power supply circuit of the voltage reference diode Z1 to make the circuit work in a stable state.

[0025] After the voltage reference diode Z1 is in the voltage stabilization state, its output voltage VREF provides a stable reference voltage for the non-inverting input terminal (+) of the operational amplifier U1. The voltage at the inverting input terminal (-) of the operational amplifier U1 is in a virtual short state with the voltage at the non-inverting input terminal, that is, the voltages at the two input terminals of the operational amplifier U1 are equal. At this time, the output voltage of the operational amplifier U1 is VREF * (1 + R4 / (R2 / / NTC)). In this way, the voltage applied across the resistor R3 is: VREF * (1 + R4 / (R2 / / NTC)) - VREF. Since the working condition of the minimum temperature coefficient (or zero temperature coefficient) of the reference diode Z1 is related to the current flowing through Z1, at a specific current point, the temperature coefficient of the reference diode Z1 is the smallest. At this time, the resistance value of R3 can be set to make the current value flowing through Z1 be in the working condition with the minimum temperature coefficient. The reference diode selected in this embodiment is 2DW14A. The working condition with the smallest temperature coefficient is when the current flowing through it is about 4 mA. Therefore, in this embodiment, the resistance value of R3 can be set to make the current flowing through it meet the condition of the minimum temperature coefficient of the reference diode Z1.

[0026] Since the resistance value of NTC is relatively limited and its resistance change cannot be precisely adjusted, the temperature compensation circuit in this embodiment uses resistor R2 in parallel with the thermistor NTC. Connecting NTC and R2 in parallel allows for precise adjustment of the resistance range and temperature control range, making it easy to match with the circuit. Generally, the voltage reference diode Z1 output (2DW14) has a negative temperature coefficient, and its output voltage VREF decreases as temperature rises. When R2 is connected in parallel with the resistor NTC (negative temperature coefficient resistor), the resistance of R2 / / NTC decreases as temperature rises. Since the output voltage of U1 is VREF*(1+R4 / (R2 / / NTC)), as the temperature rises, the output voltage of U1 increases, causing the voltage across R3 to rise. This increases the current flowing through R3 and Z1. When the current flowing through Z1 increases, its output voltage VREF increases, thus compensating for the output voltage change caused by temperature variations.

[0027] The voltage reference diode power supply circuit of this invention provides the voltage reference diode with its own output voltage, i.e., a voltage bootstrap circuit. Power is supplied to the diode via U1, improving power supply stability and making the output voltage more stable. Furthermore, a temperature compensation NTC resistor circuit is added to further correct output drift caused by temperature changes. Using a domestically produced 2DW14 reference diode, this reference power supply circuit can achieve a temperature coefficient of <5ppm, meeting the performance requirements of a 0.01 standard energy meter.

[0028] Electricity meter implementation example

[0029] The energy meter of this invention includes a voltage reference diode and a voltage reference diode power supply circuit for powering the voltage reference diode. The voltage reference diode power supply circuit includes a voltage source regulator circuit and a voltage bootstrap circuit. The voltage bootstrap circuit includes an operational amplifier. The second input terminal of the operational amplifier is connected through a temperature compensation circuit, and the first input terminal of the operational amplifier is connected to the output terminal of the voltage source regulator circuit. The output terminal of the operational amplifier is connected to the cathode of the voltage reference diode through a first resistor. The first input terminal of the operational amplifier is connected to the first resistor, and the second input terminal of the operational amplifier is also connected between the output terminal of the operational amplifier and the first resistor. The specific operation of this circuit has been described in detail in the embodiment of the voltage reference diode power supply circuit and will not be repeated here.

Claims

1. A voltage reference diode power supply circuit, comprising a voltage source regulator circuit for providing a stable voltage, characterized in that, It also includes a voltage bootstrap circuit and a temperature compensation circuit. The voltage bootstrap circuit includes an operational amplifier. The second input terminal of the operational amplifier is connected to the temperature compensation circuit. The first input terminal of the operational amplifier is connected to the output terminal of the voltage source regulator circuit. The output terminal of the operational amplifier is connected to a voltage reference diode through a first resistor. The first input terminal of the operational amplifier is also used to connect to the voltage reference diode. The second input terminal of the operational amplifier is also connected between the output terminal of the operational amplifier and the first resistor.

2. The voltage reference diode power supply circuit according to claim 1, characterized in that, The temperature compensation circuit includes a thermistor and a second resistor connected in parallel. One end of the thermistor and the second resistor are grounded, and the other end is connected to the second input terminal of the amplifier.

3. The voltage reference diode power supply circuit according to claim 1, characterized in that, A Zener diode is also installed between the first input terminal of the operational amplifier and the output terminal of the voltage source regulator circuit.

4. The voltage reference diode power supply circuit according to claim 3, characterized in that, A third resistor is also connected between the Zener diode and the first input terminal of the operational amplifier.

5. The voltage reference diode power supply circuit according to claim 1, characterized in that, The first input terminal is a non-inverting input terminal, and the second input terminal is an inverting input terminal.

6. An electricity meter, comprising a voltage reference diode and a voltage reference diode power supply circuit for supplying power to the voltage reference diode, characterized in that, The voltage reference diode power supply circuit includes a voltage source regulator circuit, a voltage bootstrap circuit, and a temperature compensation circuit. The voltage bootstrap circuit includes an operational amplifier. The second input terminal of the operational amplifier is connected to the temperature compensation circuit, the first input terminal of the operational amplifier is connected to the output terminal of the voltage source regulator circuit, the output terminal of the operational amplifier is connected to the voltage reference diode through a first resistor, the first input terminal of the operational amplifier is also used to connect to the voltage reference diode, and the second input terminal of the operational amplifier is also connected between the output terminal of the operational amplifier and the first resistor.

7. The electricity meter according to claim 6, characterized in that, The temperature compensation circuit includes a thermistor, with a second resistor connected in parallel across its two ends. One end of the parallel connection between the thermistor and the second resistor is grounded, and the other end is connected to the second input terminal of the amplifier.

8. The electricity meter according to claim 6, characterized in that, A Zener diode is also provided between the first input terminal of the operational amplifier and the output terminal of the voltage source regulator circuit.

9. The electricity meter according to claim 8, characterized in that, A third resistor is also connected between the Zener diode and the first input terminal of the operational amplifier.

10. The electricity meter according to claim 6, characterized in that, The first input terminal is a non-inverting input terminal, and the second input terminal is an inverting input terminal.

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