CN111948442A - Voltage detection circuit, voltage detection method and electric equipment - Google Patents
Voltage detection circuit, voltage detection method and electric equipment Download PDFInfo
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- CN111948442A CN111948442A CN202010791607.1A CN202010791607A CN111948442A CN 111948442 A CN111948442 A CN 111948442A CN 202010791607 A CN202010791607 A CN 202010791607A CN 111948442 A CN111948442 A CN 111948442A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/165—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values
- G01R19/16533—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application
- G01R19/16538—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application in AC or DC supplies
- G01R19/16547—Indicating that current or voltage is either above or below a predetermined value or within or outside a predetermined range of values characterised by the application in AC or DC supplies voltage or current in AC supplies
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R15/00—Details of measuring arrangements of the types provided for in groups G01R17/00 - G01R29/00, G01R33/00 - G01R33/26 or G01R35/00
- G01R15/14—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks
- G01R15/22—Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks using light-emitting devices, e.g. LED, optocouplers
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/22—Arrangements for measuring currents or voltages or for indicating presence or sign thereof using conversion of ac into dc
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/40—Testing power supplies
- G01R31/42—AC power supplies
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/20—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess voltage
- H02H3/202—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess voltage for dc systems
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Abstract
The invention discloses a voltage detection circuit, a voltage detection method and electric equipment, wherein the voltage detection circuit comprises: a rectifier connected to an alternating current power supply; the isolation detection circuit detects the direct current bus voltage of the rectifier and outputs a corresponding detection signal; and the main control chip receives the detection signal and judges whether the alternating current power supply is abnormal or not. The invention effectively improves the voltage detection precision through the rectifier and the isolation detection circuit, avoids the unstable voltage detection phenomenon, and has simple control logic, low cost and high precision.
Description
Technical Field
The invention relates to the technical field of detection circuits, in particular to a voltage detection circuit, a voltage detection method and electric equipment.
Background
In countries and regions with severe power supply conditions, because the voltage fluctuation of the power grid is too large, each fluctuation can damage electric equipment, the service life of the electric equipment is influenced if the voltage fluctuation is too large, and the electric equipment is burnt out to cause fire. In order to avoid property loss and reduce safety risk, the electric equipment needs to be provided with a voltage detection circuit, the voltage detection circuit is used for detecting voltage fluctuation of a power grid, and protection action is executed when the voltage is too low or too high, so that the electric equipment is ensured not to be influenced by the voltage fluctuation.
The existing common voltage detection circuit adopts a voltage transformer to detect, the voltage transformer is directly connected to an alternating current power supply, the phenomenon of unstable voltage detection is easy to occur, and due to the self precision difference of components, the deviation of a measurement result is large, even the normal use of electric equipment is influenced, and the after-sale feedback is caused.
Therefore, how to design a voltage detection circuit for effectively improving the detection accuracy is an urgent technical problem to be solved in the industry.
Disclosure of Invention
In order to solve the problem that the detection result of the existing voltage detection circuit is unstable, the invention provides the voltage detection circuit, the voltage detection method and the electric equipment.
The technical scheme adopted by the invention is that a voltage detection circuit is designed, and the voltage detection circuit comprises:
a rectifier connected to an alternating current power supply;
the isolation detection circuit detects the direct current bus voltage of the rectifier and outputs a corresponding detection signal;
and the main control chip receives the detection signal and judges whether the alternating current power supply is abnormal or not.
Preferably, the ac power supply supplies power to a load connected thereto, and the main control chip executes a load protection operation when it is determined that the ac power supply is abnormal.
Preferably, the isolation detection circuit outputs a first detection signal when the voltage of the direct-current bus meets a preset protection condition, and the main control chip determines that the alternating-current power supply is abnormal after receiving the first detection signal; the isolation detection circuit outputs a second detection signal when the voltage of the direct-current bus does not meet the preset protection condition, and the main control chip judges that the alternating-current power supply is normal after receiving the second detection signal.
Preferably, when the main control chip is in a low-voltage protection mode, the preset protection condition is that the voltage of the direct-current bus is below a preset low voltage; and/or when the main control chip is in a high-voltage protection mode, the preset protection condition is that the voltage of the direct-current bus is higher than the preset high voltage.
Preferably, the isolation detection circuit comprises an isolation device, the isolation device is provided with an input module and an output module which are isolated from each other, the input module is connected to a direct current bus of the rectifier through a divider resistor, and the output module is connected with the main control chip; the detection signal output by the isolation detection circuit changes along with the on-off state of the isolation device.
In one embodiment, the isolation detection circuit further comprises: the positive electrode of the input module is connected with a power supply voltage VDD through a resistor R10, the negative electrode of the input module is connected with the output end of the three-terminal voltage-stabilizing tube U3, and the divider resistor is composed of a resistor R1 and a resistor R2 which are connected in series between direct-current buses of the rectifier; the input end of the three-terminal voltage regulator tube U3 is connected with a connecting line between the resistor R1 and the resistor R2, and the three-terminal voltage regulator tube U3 controls the on-off state of the isolation device.
The isolation detection circuit further includes: triode Q2, triode Q2's collecting electrode passes through resistance R4 and connects operating voltage VCC, and triode Q2's base is connected the output module, triode Q2's emitter ground connection, triode Q2's collecting electrode connect the main control chip, and isolator controls triode Q2's on-off state.
In another embodiment, the voltage dividing resistor is composed of a resistor R1 and a resistor R2 which are connected in series between direct current buses of the rectifier, the anode of the input module is connected to a connecting line between the resistor R1 and the resistor R2, and the cathode of the input module is grounded.
The collector of the output module is connected with a working voltage VCC, the emitter of the output module is connected with two branches, one branch is connected with the main control chip through a resistor R3, and the other branch is grounded through a resistor R6.
Preferably, the isolation device is an optocoupler U1A, the input module is a light emitting diode, and the output module is a phototriode.
The invention also provides a voltage detection method, which comprises the following steps:
converting an alternating current power supply into direct current;
detecting the actual voltage of the direct current;
judging whether the actual voltage meets a preset protection condition or not;
if yes, outputting a first detection signal, and judging that the alternating current power supply is abnormal;
and if not, outputting a second detection signal and returning to detect the actual voltage of the direct current.
Preferably, the load protection operation is executed after the ac power supply abnormality is determined.
Preferably, after the load protection operation is performed, the actual voltage of the dc power is continuously detected, and if the second detection signal is output, the load recovery operation is performed first, and then the actual voltage of the dc power is detected again.
Preferably, the load protection action comprises closing the ac power connected load and the load restoration action comprises opening the ac power connected load.
The invention also provides electric equipment adopting the voltage detection circuit.
Compared with the prior art, the invention has the following beneficial effects:
1. converting alternating current into direct current, detecting the voltage of a direct current bus, wherein the detection precision is higher than that of direct detection of the alternating current;
2. utilize isolator to convert voltage signal to the weak current signal that master control chip can discern for consumer is safe and reliable more, and the suitability of circuit is stronger, detection range is wider.
Drawings
The invention is described in detail below with reference to examples and figures, in which:
FIG. 1 is a block diagram of a voltage detection circuit of the present invention;
FIG. 2 is a circuit diagram of a first embodiment of the present invention;
FIG. 3 is a schematic circuit diagram of a second embodiment of the present invention;
FIG. 4 is a DC bus voltage waveform for AC voltages below 184V in a first embodiment of the present invention;
FIG. 5 is a waveform of a detection signal when an AC voltage is lower than 184 in the first embodiment of the present invention;
FIG. 6 is a DC bus voltage waveform for AC voltages above 184V in a first embodiment of the present invention;
FIG. 7 is a waveform of a detection signal when the AC voltage is higher than 184V in the first embodiment of the present invention;
fig. 8 is a flow chart of the detection of the low voltage protection mode in the first embodiment of the present invention.
Detailed Description
As shown in fig. 1 to 3, the voltage detection circuit provided by the present invention is suitable for an electric device, especially for an electric device powered by ac power, and mainly includes: rectifier, isolation detection circuit and main control chip, each part is explained in detail below.
The ac power supply V3 supplies power to the connected load, the rectifier D2 is connected to the ac power supply to convert ac power to dc power, and the rectifier D2 may be a full-bridge rectifier circuit, that is, a rectifier circuit formed by four diodes connected to each other.
The isolation detection circuit detects the direct-current bus voltage of the rectifier D2 and outputs a corresponding detection signal, the main control chip receives the detection signal and judges whether the alternating-current power supply is abnormal, and the detection signal is a weak-current signal with the voltage lower than the direct-current bus voltage. More specifically, the isolation detection circuit comprises an isolation device, the isolation device is provided with an input module and an output module which are isolated from each other, the input module is connected to a direct current bus of a rectifier D2 through a divider resistor, a connecting circuit between the input module and an alternating current power supply is a strong current part, the output module is connected with a main control chip, the connecting circuit between the output module and the main control chip is a weak current part, and a detection signal output by the isolation detection circuit changes along with the on-off state of the isolation device. In the invention, the isolating device preferably adopts an optocoupler U1A, the input module is a light emitting diode, and the output module is a phototriode.
The isolation detection circuit outputs a first detection signal when the voltage of the direct-current bus meets a preset protection condition, the main control chip judges that the alternating-current power supply is abnormal after receiving the first detection signal, and the main control chip executes load protection action after judging that the alternating-current power supply is abnormal for protecting the electric equipment. The isolation detection circuit outputs a second detection signal when the voltage of the direct-current bus does not meet the preset protection condition, and the main control chip judges that the alternating-current power supply is normal after receiving the second detection signal.
According to the invention, alternating current is converted into direct current through the rectifier D2, the direct current bus voltage with more stable voltage fluctuation is detected, the detection precision is higher than that of direct detection of the alternating current, and then the voltage signal is converted into a weak current signal which can be identified by the main control chip through the isolating device, so that the electric equipment is safer and more reliable.
The main control chip has at least one protection mode, and the protection mode can be set to be a low-voltage protection mode or a high-voltage protection mode. When the main control chip is in a low-voltage protection mode, and the preset protection condition is that the voltage of the direct-current bus is below the preset low voltage, namely the voltage of the direct-current bus is reduced to be below the preset low voltage, the main control chip receives a first detection signal and executes a load protection action. When the main control chip is in a high-voltage protection mode, the preset protection condition is that the direct-current bus voltage is higher than the preset high voltage, namely the direct-current bus voltage rises to be higher than the preset high voltage, the main control chip receives a first detection signal and executes a load protection action.
The present invention provides two embodiments of isolation detection circuit, which are described in detail below.
As shown in fig. 2, in the first embodiment, the isolation detection circuit includes a voltage dividing resistor, a three-terminal regulator tube U3, an optocoupler U1A, a triode Q2, and the like, the voltage dividing resistor is composed of a resistor R1 and a resistor R2 connected in series between dc buses of the rectifier, a capacitor C4 connected in parallel with the voltage dividing resistor is further connected between the dc buses of the rectifier, an anode of the light emitting diode is connected to a power supply voltage VDD through a resistor R10, a cathode of the light emitting diode is connected to an output terminal of the three-terminal regulator tube U3, an input terminal of the three-terminal regulator tube U3 is connected to a connection line between the resistor R1 and the resistor R2, and a ground terminal of the three-terminal regulator tube U. And the on-off state of the isolation device is controlled by a three-terminal voltage regulator tube U3.
Operating voltage VCC is connected to triode's collecting electrode, triode's projecting pole passes through resistance R6 ground connection, triode Q2's collecting electrode passes through resistance R4 and connects operating voltage VCC, triode Q2's base passes through resistance R5 and connects triode's projecting pole, triode Q2's projecting pole ground connection, be connected with electric capacity C2 between triode Q2's base and the projecting pole, main control chip is connected to triode Q2's collecting electrode, triode Q2's collecting electrode is as the output pin who keeps apart detection circuitry, through opto-coupler U1A control triode Q2's on-off state, and then send different detected signal and give main control chip.
When the main control chip is in a low-voltage protection mode, when the voltage of a direct-current bus is greater than a preset low voltage, the direct-current bus is divided by a resistor R1 and a resistor R2, the voltage of the input end of a three-terminal voltage regulator tube U3 is greater than the reference voltage of the three-terminal voltage regulator tube U3, the three-terminal voltage regulator tube U3 is conducted, current flows through a light-emitting diode, a phototriode is conducted at the moment, namely an optocoupler U1A is conducted, a triode Q2 is conducted, the collector of a triode Q2 is at a low level, namely a second detection signal is a low-level signal, and when.
When the voltage of the direct current bus is below a preset low voltage and is divided by a resistor R1 and a resistor R2, the voltage of the input end of a three-terminal voltage regulator tube U3 is smaller than the reference voltage, the three-terminal voltage regulator tube U3 is turned off, an optocoupler U1A and a triode Q2 are not conducted, the collector of the triode Q2 is at a high level, namely a first detection signal is a high level signal, and when a main control chip detects the high level signal, the alternating current power supply is judged to be abnormal, and a load protection action is executed.
When the main control chip is in a high-voltage protection mode, the principle is similar to that of low-voltage protection, but the voltage division ratio of the voltage division resistor is required to be adjusted according to the reference voltage of the three-terminal voltage regulator tube U3, namely the voltage of the input end of the three-terminal voltage regulator tube U3 is adjusted, and the judgment logic of the main control chip is opposite to that of low-voltage protection. When the voltage of the direct current bus is lower than the preset high voltage, after the voltage is divided by the resistor R1 and the resistor R2, the voltage of the input end of the three-terminal voltage regulator tube U3 is lower than the reference voltage, the three-terminal voltage regulator tube U3 is turned off, the optocoupler U1A and the triode Q2 are not conducted, the collector of the triode Q2 is at a high level, namely the second detection signal is a high level signal, and when the main control chip detects the high level signal, the alternating current power supply is judged to be normal.
When the voltage of the direct current bus is above a preset high voltage, after the voltage is divided by a resistor R1 and a resistor R2, the voltage of the input end of a three-terminal voltage regulator tube U3 is larger than the reference voltage, the three-terminal voltage regulator tube U3 is conducted, current flows through a light emitting diode, a phototriode is conducted at the moment, namely an optocoupler U1A is conducted, a triode Q2 is conducted, the collector of the triode Q2 is at a low level, namely a second detection signal is a low level signal, and when a main control chip detects the low level signal, the alternating current power supply is judged to be abnormal, and load protection action is executed.
For convenience of understanding, the description will be given by substituting specific numerical values by taking the low-voltage protection as an example.
As shown in fig. 4 to 7, assuming that the area voltage is 230V and is low level below 184V, TL431 is selected as the three-terminal regulator U3, and PC817 is selected as the optocoupler U1A.
Selection of resistors R1 and R2
Since the local voltage is low below 184V, the device is type-selected with this voltage as a reference point. The 184V is the dc voltage of about 260V after the ac power is rectified and filtered by the rectifier D2 and the electrolytic capacitor C4. The type of the resistors R1 and R2 is selected according to the condition that the reference voltage of a three-terminal voltage regulator U3 with the model number of TL431 is 2.5V, the voltage of the input end of the three-terminal voltage regulator U3 is 2.5V and the current of the input end does not exceed the reference input current range of TL 431-0.05-10 mA (according to the specification of a manufacturer), and the requirements of resistor power consumption and derating are met when the voltage of a direct current bus is 260V. It is known that R1: R2=1:103, R1 selects 10K, R2 selects 1030K; at the moment, the current of the input end of the three-terminal voltage regulator tube U3 is about 0.25mA, and the TL431 reference input current range is met.
The resistors R4, R5, R6 and R10 are selected
The resistor R5 and the resistor R6 determine a collector current IC1 of the optocoupler U1A, the resistor R5 determines a base current IB2 of the triode Q2, the resistor R4 determines a collector current IC2 of the triode Q2, and the resistor R10 determines an input current IF of the optocoupler U1A. In order to ensure that the optocoupler U1A can fully work in a switching state, the optocoupler must be guaranteed to work in a saturation state, and the IF of the optocoupler needs to be larger than IC. To ensure that transistor Q2 operates in the on-off state, it is necessary to ensure that the saturated conduction condition of transistor Q2 is met. In order to ensure the normal work of the triode Q2 and the optocoupler, the current cannot be larger than the specification of the components.
Selection of voltages VDD, VCC
The power supply voltage VDD selects the voltage on the strong power side with small fluctuation, namely the power supply voltage on the alternating current power supply side, so that the optocoupler UIA can be ensured to always work in a saturated state, for example, when the voltage detection circuit is applied to a transformer, the voltage on the auxiliary winding side can be selected as the power supply voltage VDD. Another benefit of this design is that ac power supply and main control chip are completely isolated through the isolating device, guarantee consumer safe and reliable.
The working voltage VCC is the working voltage of the main control chip.
As shown in fig. 3, in the second embodiment, the isolation detection circuit includes a voltage dividing resistor and an optocoupler U1A, etc., the voltage dividing resistor is composed of a resistor R1 and a resistor R2 connected in series between the dc buses of the rectifier, a capacitor C4 connected in parallel with the voltage dividing resistor is further connected between the dc buses of the rectifier D2, the anode of the light emitting diode is connected to the connection line between the resistor R1 and the resistor R2, and the cathode of the light emitting diode is grounded. The collector of the phototriode is connected with a working voltage VCC, the emitter of the phototriode is connected with two branches, one branch is connected with the main control chip through a resistor R3, and the other branch is grounded through a resistor R6. The emitting electrode of the phototriode is used as an output pin of the isolation detection circuit, and different detection signals are sent to the main control chip by changing the on-off state of the optocoupler U1A.
Under the main control chip is in the low-voltage protection mode, when direct current bus voltage is greater than and predetermines the low-voltage, after resistance R1, resistance R2 partial pressure, emitting diode switches on, and the phototriode switches on this moment, and opto-coupler U1A switches on promptly, and the emission pole of phototriode is the high level, and the second detected signal is the high level signal promptly, and when the main control chip detected the high level signal, it was normal to judge alternating current power supply.
When the voltage of the direct-current bus is below a preset low voltage, after the voltage is divided by the resistor R1 and the resistor R2, the light-emitting diode is turned off, the optocoupler U1A cannot be conducted, the emitting electrode of the phototriode is at a low level, namely, the first detection signal is a low level signal, and when the main control chip detects the low level signal, the alternating-current power supply is judged to be abnormal, and the load protection action is executed.
When the main control chip is in a high-voltage protection mode, the principle is similar to that of low-voltage protection, but the voltage division ratio of the voltage division resistor needs to be adjusted according to the conducting voltage of the light-emitting diode, and the judgment logic of the main control chip is opposite to that of the low-voltage protection. When the voltage of the direct-current bus is smaller than the preset high voltage, after the voltage is divided by the resistor R1 and the resistor R2, the light-emitting diode is turned off, the optocoupler U1A cannot be conducted, the emitting electrode of the phototriode is at a low level, namely, the second detection signal is a low level signal, and when the main control chip detects the low level signal, the alternating-current power supply is judged to be normal.
When the direct current bus voltage is above the preset high voltage, after the direct current bus voltage is divided by the resistor R1 and the resistor R2, the light emitting diode is conducted, the phototriode is conducted at the moment, namely, the optocoupler U1A is conducted, the emitting electrode of the phototriode is at a high level, namely, the first detection signal is a high level signal, and when the main control chip detects the high level signal, the alternating current power supply is judged to be abnormal, and the load protection action is executed.
In the second embodiment, the type selection of the voltage dividing resistor needs to consider the working current of the isolation device to prevent the isolation device from malfunctioning, the working voltage VCC should be consistent with the working voltage of the main control chip, and the resistor R3 selects the chip current to be considered to ensure the safety of the chip.
The invention also provides a voltage detection method of the voltage detection device, which comprises the following steps:
converting an alternating current power supply into direct current;
detecting the actual voltage of the direct current;
judging whether the actual voltage meets a preset protection condition or not;
if yes, outputting a first detection signal, judging that the alternating current power supply is abnormal, executing load protection action, and returning to detect the actual voltage of the direct current;
and if not, outputting a second detection signal and returning to detect the actual voltage of the direct current.
It should be noted that the voltage detection apparatus of the present invention always maintains a detection state during the process of connecting the electric device to the power supply, continues to detect the actual voltage of the direct current after performing the load protection action, and if the second detection signal is output, performs the load recovery action first, and then returns to continue to detect the actual voltage of the direct current, where the actual voltage of the direct current is the above direct current bus voltage. Further, the load protection action includes closing the load connected to the ac power source, and the load recovery action includes opening the load connected to the ac power source.
As shown in fig. 8, to facilitate understanding of the voltage detection method, taking the low voltage protection mode in the first embodiment as an example, the voltage detection method includes the following steps:
converting an alternating current power supply into a direct current bus voltage;
dividing voltage by using a voltage dividing resistor;
detecting the voltage between the resistor R1 and the resistor R2, and judging whether the voltage is greater than the reference voltage of the three-terminal voltage regulator tube U3;
if yes, the three-terminal voltage regulator tube U3 is conducted, the optocoupler U1A is conducted, the triode Q2 is conducted, the isolation detection circuit outputs a low level signal, and the main control chip judges that the alternating current power supply is normal after detecting the low level signal;
if not, the three-terminal voltage regulator tube U3 is turned off, the optocoupler U1A is turned off, the triode Q2 is turned off, the isolation detection circuit outputs a high level signal, the main control chip judges that the alternating current power supply is abnormal after detecting the high level signal, the load protection action is executed, and the voltage between the detection resistor R1 and the detection resistor R2 is returned.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.
Claims (15)
1. A voltage detection circuit, comprising:
a rectifier connected to an alternating current power supply;
the isolation detection circuit detects the direct-current bus voltage of the rectifier and outputs a corresponding detection signal;
and the main control chip receives the detection signal and judges whether the alternating current power supply is abnormal or not.
2. The voltage detection circuit according to claim 1, wherein the ac power supply supplies power to a load connected thereto, and the main control chip performs a load protection action when it is determined that the ac power supply is abnormal.
3. The voltage detection circuit according to claim 1, wherein the isolation detection circuit outputs a first detection signal when the dc bus voltage satisfies a preset protection condition, and the main control chip determines that the ac power supply is abnormal after receiving the first detection signal;
the isolation detection circuit outputs a second detection signal when the voltage of the direct-current bus does not meet a preset protection condition, and the main control chip judges that the alternating-current power supply is normal after receiving the second detection signal.
4. The voltage detection circuit according to claim 3, wherein when the main control chip is in a low-voltage protection mode, the preset protection condition is that the dc bus voltage is below a preset low voltage;
and/or when the main control chip is in a high-voltage protection mode, the preset protection condition is that the voltage of the direct-current bus is higher than the preset high voltage.
5. The voltage detection circuit according to claim 1, wherein the isolation detection circuit comprises an isolation device, the isolation device is provided with an input module and an output module which are isolated from each other, the input module is connected to a direct current bus of the rectifier through a voltage dividing resistor, and the output module is connected to the main control chip; the detection signal output by the isolation detection circuit changes along with the on-off state of the isolation device.
6. The voltage detection circuit of claim 5, wherein the isolation detection circuit further comprises: the input module comprises a three-terminal voltage regulator tube U3, the anode of the input module is connected with a power supply voltage VDD through a resistor R10, the cathode of the input module is connected with the output end of the three-terminal voltage regulator tube U3, and the voltage dividing resistor is composed of a resistor R1 and a resistor R2 which are connected in series between direct current buses of the rectifier;
the input end of the three-terminal regulator tube U3 is connected with a connecting line between the resistor R1 and the resistor R2, and the three-terminal regulator tube U3 controls the on-off state of the isolation device.
7. The voltage detection circuit of claim 5, wherein the isolation detection circuit further comprises: triode Q2, triode Q2's collecting electrode passes through resistance R4 and connects operating voltage VCC, triode Q2's base is connected output module, triode Q2's projecting pole ground connection, triode Q2's collecting electrode is connected the main control chip, isolator control triode Q2's on-off state.
8. The voltage detection circuit according to claim 5, wherein the voltage dividing resistor comprises a resistor R1 and a resistor R2 connected in series between DC buses of the rectifier, a positive electrode of the input block is connected to a connection line between the resistor R1 and the resistor R2, and a negative electrode of the input block is grounded.
9. The voltage detection circuit of claim 5, wherein a collector of the output module is connected to a working voltage VCC, an emitter of the output module is connected to two branches, one branch is connected to the main control chip through a resistor R3, and the other branch is connected to ground through a resistor R6.
10. The voltage detection circuit according to any one of claims 5 to 9, wherein the isolation device is an optocoupler U1A, the input module is a light emitting diode, and the output module is a phototransistor.
11. A voltage detection method is characterized by comprising the following steps:
converting an alternating current power supply into direct current;
detecting an actual voltage of the direct current;
judging whether the actual voltage meets a preset protection condition or not;
if yes, outputting a first detection signal, and judging that the alternating current power supply is abnormal;
and if not, outputting a second detection signal, and returning to detect the actual voltage of the direct current.
12. The voltage detection method according to claim 11, wherein a load protection action is executed after the ac power supply abnormality is determined.
13. The voltage detection method according to claim 12, wherein after the load protection operation is performed, the actual voltage of the dc power is continuously detected, and if the second detection signal is output, the load recovery operation is performed first, and then the actual voltage of the dc power is detected again.
14. The voltage detection method of claim 13, wherein the load protection action comprises turning off the ac power connected load, and wherein the load recovery action comprises turning on the ac power connected load.
15. An electric device, characterized in that the electric device employs the voltage detection circuit according to any one of claims 1 to 10.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010791607.1A CN111948442A (en) | 2020-08-07 | 2020-08-07 | Voltage detection circuit, voltage detection method and electric equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010791607.1A CN111948442A (en) | 2020-08-07 | 2020-08-07 | Voltage detection circuit, voltage detection method and electric equipment |
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