CN110336264B - Voltage limiting circuit - Google Patents
Voltage limiting circuit Download PDFInfo
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- CN110336264B CN110336264B CN201910780439.3A CN201910780439A CN110336264B CN 110336264 B CN110336264 B CN 110336264B CN 201910780439 A CN201910780439 A CN 201910780439A CN 110336264 B CN110336264 B CN 110336264B
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- 230000000670 limiting effect Effects 0.000 title claims abstract description 87
- 238000000034 method Methods 0.000 claims abstract description 19
- 230000002159 abnormal effect Effects 0.000 claims description 23
- 230000001960 triggered effect Effects 0.000 claims description 4
- 230000015556 catabolic process Effects 0.000 claims description 3
- 230000008859 change Effects 0.000 claims description 2
- 230000001808 coupling effect Effects 0.000 claims description 2
- 230000008569 process Effects 0.000 abstract description 5
- 238000004891 communication Methods 0.000 description 13
- 230000001419 dependent effect Effects 0.000 description 8
- 238000012423 maintenance Methods 0.000 description 6
- 238000010586 diagram Methods 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
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- 230000000087 stabilizing effect Effects 0.000 description 1
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
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Abstract
The invention discloses a voltage limiting circuit, which is characterized by comprising: voltage controlled switches, resistors, positive temperature coefficient thermistors, and piezoresistors; the voltage control type switch is connected with the resistor in series and then connected with the positive temperature coefficient thermistor in parallel to form a series-parallel branch; one end of the series-parallel branch circuit is an input electrode end of the voltage limiting circuit, and the other end of the series-parallel branch circuit is an output electrode end of the voltage limiting circuit; the other end of the series-parallel branch is also connected with a piezoresistor in series; one end of the piezoresistor is connected with the series-parallel branch circuit, and the other end of the piezoresistor is a common electrode end of the voltage limiting circuit; the positive temperature coefficient thermistor is thermally coupled to the varistor. The power output capacity of the voltage limiting circuit is improved through the dynamic conduction of the resistor voltage dividing circuit, and the power divider is suitable for the power requirements of different working states of the electric energy meter; the voltage output to the electric energy meter switching power supply can be stabilized between 110 and 330 volts during power switching (in the jump process), so that the normal operation of the electric energy meter switching power supply is ensured.
Description
Technical Field
The invention relates to the technical field of regulated power supplies, in particular to a voltage limiting circuit.
Background
The switch-type voltage-stabilized power supply is a power supply part of a plurality of electronic devices and has the advantages of high efficiency, good voltage stabilizing performance, wide voltage application range and the like. In a conventional 220-volt power supply line, the voltage is often abnormally increased due to faults such as poor zero line contact or open circuit, and the highest abnormal voltage can reach approximately 380 volts. The components such as a rectifier bridge, a switching triode, a filter capacitor and the like which form the switching type voltage-stabilizing power supply are sensitive to abnormal overvoltage, and the components are easy to damage due to too high fluctuation of input voltage, so that a voltage limiting circuit is needed to limit the fluctuation of the power grid voltage below a safe value. The intelligent electric energy meter for electric energy metering adopts a switching power supply, and when the intelligent electric energy meter is connected to a 220-volt power grid, a voltage limiting circuit in the intelligent electric energy meter is required to control the fluctuation of the power grid voltage between 110 and 330 volts so as to ensure the safety of components and the normal operation of the switching power supply.
The first diagram shows a voltage limiting circuit widely applied to an old electronic electric energy meter with weak communication function, because the electric energy meter does not need too large power consumption during data transmission, only needs a power supply to provide power below 3 watts, so that the voltage limiting circuit can realize a good voltage limiting effect, a thermistor connected in series at the input end of the power supply in the circuit plays a role in voltage division, a piezoresistor connected in parallel at the output end plays a role in voltage limiting, thermal coupling between the voltage limiting circuit and the voltage limiting circuit improves response speed, and the voltage limiting circuit provides protection for each other, thereby having good practical use effect. However, with the development of the internet of things technology, the communication function of the novel intelligent electric energy meter is greatly enhanced, the corresponding power consumption is also increased, the intelligent electric energy meter has two working states, one is in a pure metering state, the power consumption is below 3 watts, the input current is within 10 milliamperes, the other is in a metering and communication (data transmission) working state, the power consumption is about 6-10 watts, the input current is about 30-100 milliamperes, and the input current has a jump process when the two working states are switched. The voltage limiting circuit in the first graph can reduce the output voltage to below 100 volts after power switching (in the jump process) due to too low output power and too narrow dynamic range, and cannot be stabilized between 110 and 330 volts, so that the switching power supply of the electric energy meter cannot work reliably and normally.
Disclosure of Invention
At least one of the purposes of the present invention is to provide a voltage limiting circuit, which is capable of adapting to different working states of a novel intelligent electric energy meter, and stably limiting the voltage output to a switching power supply terminal between 110 and 330 volts when the grid voltage exceeds 330 volts, aiming at overcoming the problems existing in the prior art.
In order to achieve the above object, the present invention adopts a technical scheme including the following aspects.
A voltage limiting method includes connecting a thermistor as an input end in series with a power grid and connecting a piezoresistor as an output end in parallel with the power grid, connecting the two ends of the piezoresistor in parallel with a load circuit, and limiting voltage of the load circuit to be protected by thermal coupling action of the thermistor and the piezoresistor when the voltage of the connected power grid is higher than a preset voltage and is in abnormal voltage, so that the voltage output to the load circuit is limited between a minimum voltage value allowed to be input and a maximum voltage value allowed to be input; the method is characterized in that a voltage control type resistor branch is connected in parallel to the thermistor, and the conduction condition of the corresponding voltage control type resistor branch is set;
when the power supply voltage is higher than the preset voltage and is in abnormal voltage, and the power change of the load circuit exceeds the preset value, the temperature of the thermistor is higher than the heat balance point above the Curie temperature point, so that the voltage at two ends of the thermistor is increased to trigger the voltage control type resistance branch to be conducted, and the power range output to the protected circuit is increased.
Preferably, in the voltage limiting method, the voltage control type resistor branch includes: a voltage controlled switch and a resistor; the voltage controlled switch is connected in series with a resistor.
Preferably, in the voltage limiting method, the on voltage value of the voltage controlled switch is greater than the difference between the maximum abnormal voltage peak value of the power grid and the maximum voltage peak value allowed to be input by the load circuit, and is less than the difference between the maximum abnormal voltage peak value of the power grid and the minimum voltage peak value allowed to be input by the load circuit.
Preferably, in the voltage limiting method, the resistor should have a value that: when the load circuit is in a minimum working current state after the voltage control type switch is triggered to be conducted, the voltage drop generated by the resistor is larger than the difference value between the maximum abnormal voltage value of the power grid and the maximum voltage value allowed to be input by the load circuit;
when the voltage control type switch is triggered to be conducted and the load circuit is in a maximum working current state, the voltage drop generated by the resistor is smaller than the difference value between the maximum voltage value allowed to be input by the load circuit and the minimum voltage value allowed to be input by the load circuit.
Further, a voltage limiting circuit includes: a voltage-controlled resistor branch, a positive temperature coefficient thermistor and a piezoresistor;
wherein the voltage controlled resistive branch comprises: a voltage controlled switch and a resistor, the voltage controlled switch being in series with the resistor; the voltage control type resistor branch is connected with the thermistor in parallel to form a series-parallel branch; one end of the series-parallel branch is an input electrode end of the voltage limiting circuit, and the other end of the series-parallel branch is led out to be a tap which is an output electrode end of the voltage limiting circuit; the other end of the series-parallel branch is also connected with the piezoresistor in series; one end of the piezoresistor is connected with the series-parallel branch circuit, and the other end of the piezoresistor is a common electrode end of the voltage limiting circuit; the thermistor is thermally coupled with the piezoresistor; the voltage limiting circuit adopts the voltage limiting method, and when the accessed power grid voltage is higher than the preset voltage and is in abnormal voltage, the voltage limiting protection is carried out on the protected circuit; when the load power changes to exceed a preset value, the temperature of the thermistor is higher than a heat balance point above the Curie temperature point, so that the voltage at two ends of the thermistor rises to trigger the voltage control type resistor branch to be conducted, and the power range output to a protected circuit is increased.
Preferably, in the voltage limiting circuit, the voltage control type switch is a discharge tube, and when the voltage of the connected power grid is 220V, the direct current breakdown voltage value of the discharge tube is 70V-380V.
Preferably, in the voltage limiting circuit, the resistance value of the resistor is 1.7 kiloohms-2.4 kiloohms.
Preferably, in the voltage limiting circuit, when the voltage of the connected power grid is 220V, the nominal voltage-sensitive voltage of the piezoresistor is 390V, and the maximum allowable alternating current working voltage is 250V.
Preferably, in the voltage limiting circuit, the voltage control switch, the resistor, the thermistor and the piezoresistor are packaged into a whole, and the corresponding electrode terminals are led out from the lead wires.
Further, an intelligent electric energy meter comprises a voltage limiting circuit adopting the voltage limiting method.
In summary, due to the adoption of the technical scheme, the invention has at least the following beneficial effects:
according to the voltage limiting circuit, the resistor voltage dividing circuit controlled by the dynamic switch (voltage control switch) is connected in parallel to two ends of the thermistor, and through setting of corresponding element parameters, the voltage control switch can be adapted to dynamic conduction of different power states of the load circuit (protected circuit), so that when the resistor is connected to the voltage limiting circuit when the voltage control switch is conducted, the power output capacity of the voltage limiting circuit is improved, the voltage limiting circuit can output a power value with a wider dynamic range, and the power value output by the voltage limiting circuit can be adapted to the power requirements of different working states of the load circuit under the abnormal state of the power grid voltage; the resistor voltage dividing circuit can also enable the voltage output to the electric energy meter switching power supply to be stabilized between 110 and 330 volts during power switching (in a jump process), thereby ensuring the normal operation of the electric energy meter switching power supply.
Drawings
Fig. 1 is a circuit diagram of a voltage limiting circuit applied to an old electronic electric energy meter with weak communication function in the prior art.
Fig. 2 is a voltage limiting circuit diagram according to an exemplary embodiment of the present invention.
Reference numerals: 101-a thermistor; 102-piezoresistor; 1-an input electrode terminal; 2-an output electrode terminal; 3-an input electrode terminal; 4-piezoresistors; 5-thermistor (positive temperature coefficient thermistor); 6-voltage controlled switch; 7-resistor 7.
Detailed Description
The present invention will be described in further detail with reference to the drawings and examples, so that the objects, technical solutions and advantages of the present invention will become more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Fig. 2 shows a voltage limiting circuit according to an exemplary embodiment of the present invention. The circuit of this embodiment mainly includes: a voltage controlled switch 6, a resistor 7, a positive temperature coefficient thermistor 5 and a varistor 4;
wherein, the voltage control switch 6 is connected in series with the resistor 7 and then connected in parallel with the positive temperature coefficient thermistor 5 to form a series-parallel branch; one end of the series-parallel branch is an input electrode end 1 of the voltage limiting circuit, and the other end of the series-parallel branch is led out to be tapped as an output electrode end 2 of the voltage limiting circuit; the other end of the series-parallel branch is also connected with the piezoresistor 4 in series; one end of the piezoresistor 4 is connected with the series-parallel branch circuit, and the other end of the piezoresistor is a common electrode end of the voltage limiting circuit; the ptc thermistor 5 is thermally coupled to the varistor 4.
Specifically, in actual use, the input electrode terminal of the voltage limiting circuit is connected with a 220 volt power grid line, the output electrode terminal of the voltage limiting circuit is connected with a load circuit (taking an electric energy meter switching power supply as an example), the normal working voltage range of the switching power supply is between 110 and 330 volts, the voltage-sensitive voltage of the voltage dependent resistor is 390 volts, and the maximum allowable alternating current working voltage is 250 volts. According to the stable state of the power grid voltage and the working state of the electric energy meter, the voltage limiting circuit has three different working modes, namely the following steps:
the first working mode is as follows: when the voltage of the power grid connected to the input electrode terminal is lower than 250V, the piezoresistor is in a state of high resistance and no heat, the thermistor is also in a normal temperature state, the thermistor is in a zero-power resistance value, and the thermistor is in a low-resistance state. At this time, the current flowing through the thermistor is lower than the minimum operating current of the thermistor at normal temperature, regardless of whether the ammeter is in the metering state or the communication state, and the thermistor cannot generate heat and the resistance value cannot be increased. At this time, since the thermistor is in a low-resistance state, the voltage drop on the thermistor is very small (the voltage division is very small), and the voltage limiting circuit can be approximately considered to be inoperative, and the power grid voltage is almost directly applied to the switching power supply of the electric energy meter.
The second mode of operation: when the voltage of the power grid connected to the input electrode exceeds 250V (at an abnormal voltage value), the voltage dependent resistor starts to flow current and starts to generate heat, the heat generated by the voltage dependent resistor is thermally coupled to the thermistor to increase the resistance of the thermistor due to heating, the partial pressure on the thermistor is increased, the current flowing into the voltage dependent resistor is slowed down, along with the increase of the voltage of the power grid, when the current flowing into the voltage dependent resistor reaches 10-30 mA, the heat balance can be achieved above the Curie temperature point, the thermistor shares a part of abnormal overvoltage, and the voltage output to the switch power supply end is limited to 330V. If the electric energy meter works in a metering state, the current flowing through the thermistor only needs to be divided into a plurality of milliamperes to flow into the switching power supply, the heat generated by the incremental current cannot enable the temperature of the thermistor to continuously rise away from a heat balance point, the resistance value of the thermistor cannot be continuously increased, the voltage division at two ends of the thermistor cannot be continuously increased, at the moment, if the conducting voltage value of the voltage control type switch in the voltage limiting circuit is set to be higher than the voltage value of the voltage division value, the voltage control type switch cannot be turned on, and accordingly, no current flows through a branch circuit connected with the voltage control type switch in series. At this time, the output power of the voltage limiting circuit can ensure the normal operation of the electric energy meter in the metering state.
When the voltage of the power grid is recovered to be normal, the voltage at two ends of the piezoresistor is smaller than 250V, the piezoresistor returns to a high-resistance non-conducting state, no heat is generated, the thermistor cannot be coupled to the heat, the resistance begins to drop, the partial pressure of the thermistor is reduced, and finally the piezoresistor returns to the first working mode.
The third working mode is as follows: if the electric energy meter is in an abnormal state of the power grid voltage and works in a communication state, the current output by the voltage limiting circuit to the switching power supply needs to be increased to tens of milliamperes, so that the thermistor additionally generates more than 1 watt of power consumption due to the increase of the current, the generated additional heat can enable the temperature of the thermistor to be separated from a heat balance point to continuously rise, the temperature of the thermistor is slightly raised above the Curie temperature point of the positive temperature coefficient thermistor to cause the rapid increase of the resistance, the partial pressure at the two ends of the thermistor also rapidly rises, and the voltage output to the switching power supply end of the electric energy meter also can be reduced. Once the partial pressure at the two ends of the thermistor exceeds the conducting voltage of the voltage control type switch, the switch is conducted, the resistor is connected with the thermistor in parallel, the power output capacity of the voltage limiting circuit is improved, and the voltage output to the switch power supply end is ensured to be maintained between 110 and 330 volts.
In order to enable the voltage limiting circuit to adapt to the stable state of the power grid voltage and the working state of the electric energy meter to realize the switching between the second working mode and the third working mode, the switching-on voltage of the voltage control switch is selected to be larger than the difference value between the maximum abnormal voltage peak value of the power grid and the maximum voltage peak value allowed to be output by the voltage limiting circuit and smaller than the difference value between the maximum abnormal voltage peak value of the power grid and the minimum voltage peak value allowed to be output by the voltage limiting circuit. In a further embodiment of the invention, the voltage controlled switch may be operated as a discharge tube, the dc breakdown voltage of which may be between 70 and 380 volts when used in a voltage limiting circuit of an electric energy meter connected to a 220 volt power grid.
Further, the lower limit of the resistance value of the resistor connected in series with the voltage control switch should be satisfied so that the voltage drop generated by the resistance value is equal to the difference between the maximum abnormal voltage value of the power grid and the maximum allowable voltage value output to the switch power supply terminal when the resistor is switched to the minimum working current after the communication state through the electric energy meter. The upper limit of the resistance value of the resistor is selected to be satisfied so that the voltage drop generated by the resistance value is equal to the difference between the maximum allowable voltage value and the minimum allowable voltage value output to the switch power supply end by the voltage limiting circuit when the resistor is switched to the maximum working current in the communication state by the electric energy meter. If the electric energy meter working in the 220V power grid is set, 10 watts of power is required to be consumed in a communication state, when the voltage of the switch power supply terminal is 330V of the highest allowable value, the input working current is 30 mA of the minimum value, and when the voltage of the switch power supply terminal is 110V of the lowest allowable value, the input working current is 90 mA of the maximum value; the maximum abnormal voltage of the power grid is 380 volts. Then the lower limit of the resistor resistance is rl= (380 volt-330 volt)/0.03 amp = 1.7 kilo ohm, the upper limit of the resistor resistance R H = (330 volts-110 volts)/0.09 ampere = 2.4 kiloohms. Here, in order to facilitate explanation of the working principle and omit complicated nonlinear calculation, the setting ignores the partial pressure of the lowest maintenance on voltage value of the discharge tube and the shunt influence of the thermistor in different resistance states, and in practical application, some engineering correction can be performed, so long as the experiment verification support exists, and the upper and lower limits of the resistance values have large errors which are acceptable.
After the element parameters are optimized according to the thought, when the abnormal voltage of the power grid reaches a high position above 330V, once the electric energy meter enters a communication state, a voltage control type switch (discharge tube) is conducted, and the voltage output to the switch power supply end is reduced to between 110 and 330V, so that the normal operation of the switch power supply of the electric energy meter is ensured. At this time, the voltage dependent resistor will reduce or stop heating, so that the resistance of the thermistor is reduced, the current flowing through the thermistor is increased, the corresponding shunt flowing through the resistor starts to reduce, when the resistance of the thermistor is reduced to a certain extent, the voltage at two ends of the voltage dependent resistor starts to rise again, the voltage dependent resistor starts to generate heat again, further reduction of the resistance of the thermistor is prevented, and the voltage output to the switching power supply of the electric energy meter is balanced again at 330V.
When the electric energy meter finishes the communication function and returns to the metering state, the current flowing into the switching power supply of the electric energy meter suddenly drops from tens of milliamperes to a few milliamperes, the shunt flowing through the resistor is smaller than the lowest maintenance discharge current of the discharge tube (the maintenance current is larger than about 20 milliamperes to keep the discharge tube conducting), the discharge tube is disconnected, and the circuit returns to the state of the second working mode.
If the ammeter still works in the communication state, the power grid voltage is restored to the normal voltage, at the moment, the piezoresistor also stops heating, the resistance value of the thermistor is reduced, the shunt is increased, the current flowing through the resistor is reduced, until the shunt flowing through the resistor is reduced to be smaller than the lowest maintenance current of the discharge tube or the voltage across the thermistor is reduced to be smaller than the lowest maintenance voltage of the discharge tube (the maintenance voltage is greater than about 30 volts to keep the discharge tube conducting), the discharge tube is disconnected, and the circuit directly returns to the state of the first working mode. In summary, the voltage limiting circuit in this example dynamically improves the power output capability of the voltage limiting circuit by connecting the thermistor in parallel with a resistor voltage dividing circuit (voltage control type switch) controlled by a dynamic switch, so that the dynamic output power range of the voltage limiting circuit is wider, and the voltage limiting circuit can adapt to the power requirements of the electric energy meter when the electric energy meter is in an abnormal state of the power grid voltage and works in a communication state, and also ensures that the voltage output to the electric energy meter switching power supply in the jump process can be stabilized between 110 and 330 volts, thereby ensuring the normal work of the electric energy meter switching power supply.
Besides the application in the electric energy meter, the voltage limiting circuit can be applied to other electric appliances with low-power switching power supplies, such as LED lighting appliances, in which the switching power supplies do not necessarily have a large power state and a small power state, and the corresponding voltage limiting circuit only has two working states of a working mode 1 and a working mode 3.
The foregoing is a detailed description of specific embodiments of the invention and is not intended to be limiting of the invention. Various alternatives, modifications and improvements will readily occur to those skilled in the relevant art without departing from the spirit and scope of the invention.
Claims (10)
1. A voltage limiting method includes connecting a thermistor as an input end in series with a power grid and connecting a piezoresistor as an output end in parallel with the power grid, connecting the two ends of the piezoresistor in parallel with a load circuit, and limiting voltage of the load circuit to be protected by thermal coupling action of the thermistor and the piezoresistor when the voltage of the connected power grid is higher than a preset voltage and is in abnormal voltage, so that the voltage output to the load circuit is limited between a minimum voltage value allowed to be input and a maximum voltage value allowed to be input; the method is characterized in that a voltage control type resistor branch is connected in parallel to the thermistor, and the conduction condition of the corresponding voltage control type resistor branch is set;
when the power change of the load circuit exceeds a preset value, the temperature of the thermistor is higher than a heat balance point above a Curie temperature point, and the voltage at two ends of the thermistor is increased to trigger the voltage control type resistor branch to be conducted, so that the power range output to a protected circuit is increased.
2. The voltage limiting method of claim 1, wherein the voltage controlled resistive branch comprises: a voltage controlled switch and a resistor; the voltage controlled switch is connected in series with a resistor.
3. The voltage limiting method of claim 2, wherein the on voltage value of the voltage controlled switch is greater than the difference between the maximum abnormal voltage peak value of the power grid and the maximum voltage peak value allowed to be input by the load circuit and is less than the difference between the maximum abnormal voltage peak value of the power grid and the minimum voltage peak value allowed to be input by the load circuit.
4. The voltage limiting method of claim 2, wherein the resistor should have a value that: when the load circuit is in a minimum working current state after the voltage control type switch is triggered to be conducted, the voltage drop generated by the resistor is larger than the difference value between the maximum abnormal voltage value of the power grid and the maximum voltage value allowed to be input by the load circuit;
when the voltage control type switch is triggered to be conducted and the load circuit is in a maximum working current state, the voltage drop generated by the resistor is smaller than the difference value between the maximum voltage value allowed to be input by the load circuit and the minimum voltage value allowed to be input by the load circuit.
5. A voltage limiting circuit, the voltage limiting circuit comprising: a voltage-controlled resistor branch, a positive temperature coefficient thermistor and a piezoresistor;
wherein the voltage controlled resistive branch comprises: a voltage controlled switch and a resistor, the voltage controlled switch being in series with the resistor; the voltage control type resistor branch is connected with the thermistor in parallel to form a series-parallel branch; one end of the series-parallel branch is an input electrode end of the voltage limiting circuit, and the other end of the series-parallel branch is led out to be a tap which is an output electrode end of the voltage limiting circuit; the other end of the series-parallel branch is also connected with the piezoresistor in series; one end of the piezoresistor is connected with the series-parallel branch circuit, and the other end of the piezoresistor is a common electrode end of the voltage limiting circuit; the thermistor is thermally coupled with the piezoresistor; the voltage limiting circuit adopts the method as set forth in any one of claims 1-4, and performs voltage limiting protection on the protected circuit when the accessed power grid voltage is higher than a preset voltage and is at an abnormal voltage; when the load power changes to exceed a preset value, the temperature of the thermistor is higher than a heat balance point above the Curie temperature point, so that the voltage at two ends of the thermistor rises to trigger the voltage control type resistor branch to be conducted, and the power range output to a protected circuit is increased.
6. The voltage limiting circuit of claim 5, wherein the voltage controlled switch is a discharge tube, and the dc breakdown voltage of the discharge tube is 70V-380V when the connected grid voltage is 220V.
7. The voltage limiting circuit of claim 5, wherein the resistor has a value of 1.7 kiloohms to 2.4 kiloohms.
8. The voltage limiting circuit of claim 5 wherein the nominal voltage sensitive voltage of the varistor is 390V and the maximum allowable ac operating voltage is 250V when the connected grid voltage is 220V.
9. The voltage limiting circuit of any one of claims 5-8, wherein the voltage controlled switch, resistor, thermistor and varistor are packaged as one unit with the respective electrode terminals routed from leads.
10. The intelligent electric energy meter comprises a voltage limiting circuit adopting the voltage limiting method of any one of claims 1-4.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201910780439.3A CN110336264B (en) | 2019-08-22 | 2019-08-22 | Voltage limiting circuit |
| PCT/CN2020/103038 WO2021031766A1 (en) | 2019-08-22 | 2020-07-20 | Voltage limiting circuit |
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| CN201910780439.3A CN110336264B (en) | 2019-08-22 | 2019-08-22 | Voltage limiting circuit |
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| CN110336264B true CN110336264B (en) | 2024-01-26 |
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| CN110336264B (en) * | 2019-08-22 | 2024-01-26 | 成都铁达电子股份有限公司 | Voltage limiting circuit |
| CN114003118A (en) * | 2020-07-28 | 2022-02-01 | 华为技术有限公司 | Server power supply circuit and server |
| CN114825299A (en) * | 2022-05-24 | 2022-07-29 | 西安图为电气技术有限公司 | Voltage control circuit and soft start circuit |
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Also Published As
| Publication number | Publication date |
|---|---|
| WO2021031766A1 (en) | 2021-02-25 |
| CN110336264A (en) | 2019-10-15 |
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