CN116577540A - Primary side voltage detection circuit, charging device and electric vehicle - Google Patents

Primary side voltage detection circuit, charging device and electric vehicle Download PDF

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Publication number
CN116577540A
CN116577540A CN202310856490.4A CN202310856490A CN116577540A CN 116577540 A CN116577540 A CN 116577540A CN 202310856490 A CN202310856490 A CN 202310856490A CN 116577540 A CN116577540 A CN 116577540A
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China
Prior art keywords
circuit
voltage
voltage detection
resistor
primary
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Granted
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CN202310856490.4A
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Chinese (zh)
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CN116577540B (en
Inventor
林木松
李微
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Pluckystone Technologies Co ltd
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Pluckystone Technologies Co ltd
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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L53/00—Methods of charging batteries, specially adapted for electric vehicles; Charging stations or on-board charging equipment therefor; Exchange of energy storage elements in electric vehicles
    • 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
    • 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
    • G01R19/0084—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring voltage only
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/02—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries for charging batteries from ac mains by converters
    • H02J7/04—Regulation of charging current or voltage
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0003—Details of control, feedback or regulation circuits
    • H02M1/0006—Arrangements for supplying an adequate voltage to the control circuit of converters
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/08—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
    • H02M1/088—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices
    • H02M1/092—Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters for the simultaneous control of series or parallel connected semiconductor devices the control signals being transmitted optically
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
    • H02M5/02—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc
    • H02M5/04—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters
    • H02M5/10—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using transformers
    • H02M5/12—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using transformers for conversion of voltage or current amplitude only
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K19/00—Logic circuits, i.e. having at least two inputs acting on one output; Inverting circuits
    • H03K19/0175—Coupling arrangements; Interface arrangements
    • H03K19/017509—Interface arrangements
    • H03K19/017536—Interface arrangements using opto-electronic devices
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03K—PULSE TECHNIQUE
    • H03K7/00—Modulating pulses with a continuously-variable modulating signal
    • H03K7/08—Duration or width modulation ; Duty cycle modulation
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J2207/00—Indexing scheme relating to details of circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J2207/20—Charging or discharging characterised by the power electronics converter
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/70—Energy storage systems for electromobility, e.g. batteries
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/7072—Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors

Abstract

The invention discloses a primary side voltage detection circuit, a charging device and an electric vehicle, wherein the charging device is provided with a transformer, and the primary side voltage detection circuit comprises: the voltage input end of the controller is used for accessing the primary side voltage of the transformer and outputting a voltage detection signal corresponding to the duty ratio according to the primary side voltage; the positive electrode of the transmitting end of the optical coupler is connected with the output end of the controller, and the optical coupler is used for isolating and outputting the voltage detection signal; the current adjusting element is connected in series between the output end of the controller and the positive electrode of the transmitting end of the optocoupler, and is used for adjusting the current output to the positive electrode of the transmitting end of the optocoupler so that the optocoupler works in a saturation region. The technical scheme of the invention aims to improve the accuracy of primary side voltage detection of the transformer.

Description

Primary side voltage detection circuit, charging device and electric vehicle
Technical Field
The invention relates to the field of voltage detection, in particular to a primary side voltage detection circuit, a charging device and an electric vehicle.
Background
At present, when an electric device is charged through a charging device, a transformer of the charging device converts high voltage of mains supply into low voltage to charge the electric device, and for different primary side voltages of the transformer, the charging device needs to charge the electric device by adopting corresponding charging voltage curves, so that the primary side voltage of the transformer needs to be detected, and in the process of detecting the primary side voltage, in order to prevent the high voltage of the mains supply from leaking to the secondary side of the transformer, electric shock risks and circuit faults are caused, an isolation device or an isolation circuit is usually arranged, and electric isolation is realized; the primary voltage detected after isolation by the isolation circuit has a certain deviation from the actual primary voltage, because devices in the isolation device may be affected by surrounding environment factors, for example, an optocoupler is used for isolation, and the optocoupler can change an amplification factor due to temperature change of the surrounding environment, so that output voltage is affected, and the detection result is inaccurate.
Disclosure of Invention
The invention mainly aims to provide a primary side voltage detection circuit, a charging device and an electric vehicle, and aims to improve the accuracy of primary side voltage detection of a transformer.
In order to achieve the above object, a primary side voltage detection circuit according to the present invention is applied to a charging device having a transformer, the primary side voltage detection circuit comprising:
the voltage input end of the controller is used for accessing the primary side voltage of the transformer and outputting a voltage detection signal corresponding to the duty ratio according to the primary side voltage;
the positive electrode of the transmitting end of the optical coupler is connected with the output end of the controller, and the optical coupler is used for isolating and outputting the voltage detection signal;
the current adjusting element is arranged between the output end of the controller and the positive electrode of the transmitting end of the optocoupler in series, and is used for adjusting the current output to the positive electrode of the transmitting end of the optocoupler so that the optocoupler works in a saturation region.
Optionally, the primary side voltage detection circuit further includes:
the input end of the signal synchronization circuit is connected with the emitter of the receiving end of the optocoupler, the power end of the signal synchronization circuit is used for being connected with a direct-current power supply, and the signal synchronization circuit is used for outputting pulse signals with the same duty ratio as the voltage detection signals according to the voltage detection signals.
Optionally, the signal synchronization circuit includes a first resistor, a second resistor, a third resistor, a first NPN triode and a first PNP triode, a first end of the first resistor is connected with a first end of the second resistor and is an input end of the signal synchronization circuit, a second end of the first resistor, a first end of the third resistor, a base of the first NPN triode and a base of the first PNP triode are interconnected, a second end of the second resistor, a second end of the third resistor and a collector of the first PNP triode are grounded, an emitter of the first NPN triode is connected with an emitter of the first PNP triode and is an output end of the signal synchronization circuit, and a collector of the first NPN triode is connected with a dc power supply voltage.
Optionally, the primary side voltage detection circuit further includes:
the input end of the second filter circuit is connected with the output end of the signal synchronization circuit, and the second filter circuit is used for filtering the pulse signal output by the signal synchronization circuit and outputting the pulse signal.
Optionally, the second filter circuit includes a fourth resistor, a fifth resistor, a first capacitor and a second capacitor, where a first end of the fourth resistor is connected to the output end of the signal synchronization circuit, a second end of the fourth resistor, a first end of the fifth resistor and a first end of the first capacitor are interconnected, a second end of the fifth resistor is connected to a first end of the second capacitor and is an output end of the second filter circuit, and a second end of the first capacitor and a second end of the second capacitor are grounded.
Optionally, the current adjusting element is an adjustable resistor.
Optionally, the primary side voltage detection circuit further includes:
the input end of the rectifying circuit is used for being connected with the primary side voltage of the transformer, and the rectifying circuit is used for rectifying the primary side voltage and then outputting direct current voltage;
the input end of the voltage reduction circuit is connected with the output end of the rectifying circuit, and the voltage reduction circuit is used for carrying out voltage reduction conversion on the direct-current voltage output by the rectifying circuit and then outputting the direct-current voltage;
the input end of the first filter circuit is connected with the output end of the voltage reduction circuit, the output end of the first filter circuit is connected with the input end of the controller, and the first filter circuit is used for filtering the direct current voltage output by the voltage reduction circuit and outputting the direct current voltage to the controller.
Optionally, the primary side voltage detection circuit further includes:
the temperature detection circuit is connected with the temperature input end of the controller, and is used for detecting the ambient temperature and outputting a temperature detection signal to the controller, and the controller is also used for controlling the primary side voltage detection circuit to stop working when the ambient temperature value detected by the temperature detection signal exceeds a temperature threshold value.
The invention also provides a charging device which comprises a transformer and the primary side voltage detection circuit.
The invention also provides an electric vehicle comprising the charging device.
The technical scheme of the invention comprises a primary side voltage detection circuit formed by a controller, an optocoupler and a current regulating element, wherein the voltage input end of the controller is used for accessing the primary side voltage of a transformer and outputting a voltage detection signal corresponding to the duty ratio according to the primary side voltage; the positive electrode of the transmitting end of the optical coupler is connected with the output end of the controller, and the optical coupler is used for isolating and outputting the voltage detection signal; the current adjusting element is connected in series between the output end of the controller and the positive electrode of the transmitting end of the optocoupler, and is used for adjusting the current output to the positive electrode of the transmitting end of the optocoupler so that the optocoupler works in a saturation region. Therefore, the optocoupler cannot be affected by the ambient temperature, and the transmission of the electric signals is more stable. The technical scheme of the invention aims to improve the accuracy of primary side voltage detection of the transformer.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to the structures shown in these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a schematic diagram of a functional module of an embodiment of a primary side voltage detection circuit according to the present invention;
FIG. 2 is a schematic diagram of a functional module of another embodiment of the primary side voltage detection circuit of the present invention;
FIG. 3 is a schematic circuit diagram of a primary side voltage detection circuit according to an embodiment of the present invention;
fig. 4 is a schematic circuit diagram of a primary voltage detection circuit according to another embodiment of the present invention.
Reference numerals illustrate:
the achievement of the objects, functional features and advantages of the present invention will be further described with reference to the accompanying drawings, in conjunction with the embodiments.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be noted that, if directional indications (such as up, down, left, right, front, and rear … …) are included in the embodiments of the present invention, the directional indications are merely used to explain the relative positional relationship, movement conditions, etc. between the components in a specific posture (as shown in the drawings), and if the specific posture is changed, the directional indications are correspondingly changed.
In addition, if there is a description of "first", "second", etc. in the embodiments of the present invention, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying a relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions of the embodiments may be combined with each other, but it is necessary to base that the technical solutions can be realized by those skilled in the art, and when the technical solutions are contradictory or cannot be realized, the combination of the technical solutions should be considered to be absent and not within the scope of protection claimed in the present invention.
The invention provides a primary side voltage detection circuit which is applied to a charging device, wherein the charging device is provided with a transformer. The charging device can be a device such as a charging pile and a power adapter for charging the electric device, the charging device usually converts commercial power into low voltage to charge the electric device, and for different primary side voltages of the transformers, the charging device needs to charge the electric device by adopting corresponding charging voltage curves, so that the primary side voltage of the transformers needs to be detected, and in the process of detecting the primary side voltage, in order to prevent high voltage of the commercial power from leaking to the secondary side of the transformers, electric shock risks and circuit faults are caused, an isolation device or an isolation circuit is usually arranged, so that electric isolation is realized; the primary voltage detected after isolation by the isolation circuit has a certain deviation from the actual primary voltage, because devices in the isolation device may be affected by surrounding environment factors, for example, an optocoupler is used for isolation, and the optocoupler can change an amplification factor due to temperature change of the surrounding environment, so that output voltage is affected, and the detection result is inaccurate.
Referring to fig. 1, in an embodiment of the present invention, the primary side voltage detection circuit includes:
the voltage input end of the controller 10 is used for accessing the primary side voltage of the transformer and outputting a voltage detection signal corresponding to the duty ratio according to the primary side voltage;
the positive electrode of the transmitting end of the optical coupler 30 is connected with the output end of the controller 10, and the optical coupler 30 is used for isolating and outputting the voltage detection signal;
the current adjusting element 20 is serially connected between the output end of the controller 10 and the positive electrode of the emitting end of the optocoupler 30, and the current adjusting element 20 is used for adjusting the current output to the positive electrode of the emitting end of the optocoupler 30, so that the optocoupler 30 works in a saturation region.
In this embodiment, the controller 10 may adopt a microprocessor, an MCU, a single chip microcomputer or other electronic components, the controller 10 may collect the primary side voltage of the transformer through the ADC acquisition port, the primary side of the transformer in the charging device may be connected to a power grid, and the power supply is connected to the power supply, so that the controller 10 may be damaged due to the excessively high voltage of the power supply, and therefore, a voltage stabilizing filter circuit may be disposed between the ADC acquisition port of the controller 10 and the primary side of the transformer, and the primary side voltage of the transformer may be output to the controller 10 after being stabilized and filtered, so that the controller 10 may work normally. After the primary voltage of the transformer is collected by the controller 10 through the ADC collection port, a voltage value can be obtained through calculation of the internal ADC module, then PWM signals with corresponding duty ratios are output according to the obtained voltage value, namely voltage detection signals are sent to the optocoupler 30, the detected different voltage values are represented by the PWM signals with different duty ratios, for example, the voltage of 0V-220V of the mains supply connected to the transformer can be detected by the controller 10 after voltage stabilization filtering, if the voltage detected by the controller 10 is 5V, PWM signals with the duty ratio of one hundred percent can be output, and if the voltage detected by the controller 10 is 0V, PWM signals with the duty ratio of zero percent can be output. Because the optocoupler 30 is a device that works according to the current connected to the positive electrode of the transmitting end, the voltage detected by the controller 10 fluctuates in the range of 0v to 5v, if the current at the input end of the optocoupler 30 is controlled by detecting the voltage, the current at the input end of the optocoupler 30 will be unstable and cannot work normally; therefore, the voltage value needs to be changed into a PWM signal with a corresponding duty ratio by the controller 10, and since the voltage of the PWM signal is stabilized at a fixed high level or low level, the current output to the positive electrode of the transmitting end of the optocoupler 30 can be stably controlled, so that the optocoupler 30 works normally. The specific voltage of the primary side of the transformer can be changed according to the actual application place.
In the embodiment, the optocoupler 30 is used as a device for realizing electrical isolation, so that the controller 10 in the primary side voltage detection circuit and a power chip on the secondary side of the transformer can be isolated, and the high voltage on the primary side is ensured not to be output to the secondary side, so that the secondary side circuit is damaged; compared with isolation devices such as Hall elements, the optocoupler 30 has lower cost, so that in the application scene of a plurality of small-sized charging devices, the optocoupler 30 is adopted for isolation, and the overall cost is lower; after the collector of the receiving end of the optocoupler 30 is connected with a direct-current voltage V1 and the controller 10 outputs a PWM signal with a corresponding duty ratio, the light receiving tube of the optocoupler 30 is turned on or off according to the PWM signal, so that the duty ratio of the PWM signal is synchronized to the direct-current voltage V1; for example, the collector of the receiving end of the optocoupler 30 is connected to a 12V dc voltage V1, and the voltage value of the 12V dc voltage V1 output under different duty ratios is actually 0V-12V, so that the voltage value can correspond to 0V-220V of the primary side of the transformer. It can be understood that the secondary side of the charging device is provided with a power chip, the optocoupler 30 outputs voltage to the power chip on the secondary side of the transformer, the power chip can obtain the voltage on the primary side according to the voltage output by the optocoupler 30, for example, the primary side voltage which is 220V normally fluctuates to be 110V, the voltage is output to the controller 10 after voltage stabilization filtering, at this moment, the controller 10 outputs a PWM signal with fifty percent of duty ratio to the optocoupler 30, after the optocoupler 30 receives the PWM signal with fifty percent of duty ratio, in a voltage signal period, a positive electrode of a transmitting end receives high-level voltage, that is, the current in the circuit is large current, the light receiving tube is turned on, a direct-current voltage V1 connected to a collector of a receiving end is output to the power chip on the secondary side of the transformer, a positive electrode of a receiving end receives low-level voltage, that is small current in the circuit, the light receiving tube is turned off, and the direct-current V1 is not output to the power chip on the secondary side of the transformer, and if the direct-current voltage V1 is 12V, the total voltage value of the power chip is 6V in a voltage signal period corresponds to the voltage corresponding to the primary side voltage of the voltage 110. The power supply chip adjusts the charging voltage curve of the charging device according to the change condition of the primary side voltage, such as the reduction of the primary side voltage, and correspondingly adjusts the voltage reduction of the charging device output to the electric equipment, so that the charging efficiency of the charging device is improved, and the service life of the charging device is prolonged.
It should be noted that, when the optocoupler 30 operates in the amplifying region, the current amplification factor is affected by the ambient temperature, because the characteristics of the photosensitive element in the optocoupler 30 are temperature sensitive, and the current amplification factor changes with the change of temperature. As the ambient temperature increases, the conductivity of the photosensitive element increases, resulting in an increase in the current amplification factor; when the ambient temperature is reduced, the conductivity of the photosensitive element is reduced, the current amplification factor is reduced, and the change of the amplification factor leads to the change of the output voltage of the optocoupler 30, so that the computational complexity is increased; in this embodiment, by setting the current adjusting element 20, the current received by the positive electrode of the transmitting end of the optocoupler 30 is adjusted to be greater than or equal to the minimum working current required by the optocoupler 30 to work in the saturation region, when the PWM signal is at a high level, the optocoupler 30 works in the saturation region, and when the PWM signal is at a low level, the optocoupler 30 works in the cut-off region, so that the optocoupler 30 cannot work in the amplifying region, when the optocoupler 30 works in the saturation region, the photosensitive element is in a saturated on state, the output current of the photosensitive element reaches the maximum value, and the photosensitive element is in a stable state, so that the optocoupler 30 cannot be affected by the ambient temperature, and the voltage output from the optocoupler 30 to the power chip is more accurate. The current adjusting element 20 may be a resistor, and the specific resistance of the resistor may be determined according to the minimum working current of the saturation region of the optocoupler 30 and the PWM signal high level voltage output by the controller 10.
The technical scheme of the invention comprises a primary side voltage detection circuit formed by a controller 10, an optocoupler 30 and a current regulating element 20, wherein the voltage input end of the controller 10 is used for accessing the primary side voltage of a transformer and outputting a voltage detection signal corresponding to the duty ratio according to the primary side voltage; the positive electrode of the transmitting end of the optical coupler 30 is connected with the output end of the controller 10, and the optical coupler 30 is used for isolating and outputting a voltage detection signal; the current adjusting element 20 is serially connected between the output end of the controller 10 and the positive electrode of the emitting end of the optocoupler 30, and the current adjusting element 20 is used for adjusting the current output to the positive electrode of the emitting end of the optocoupler 30, so that the optocoupler 30 works in a saturation region. So that the optocoupler 30 is not affected by the ambient temperature, and the transmission of the electric signal is more stable. The technical scheme of the invention aims to improve the accuracy of primary side voltage detection of the transformer.
Referring to fig. 2, in an embodiment, the primary side voltage detection circuit further includes:
the input end of the signal synchronization circuit 40 is connected with the emitter of the receiving end of the optocoupler 30, the power end of the signal synchronization circuit 40 is used for being connected with a direct current power supply, and the signal synchronization circuit 40 is used for outputting a pulse signal with the same duty ratio as the voltage detection signal according to the voltage detection signal.
In this embodiment, since the optocoupler 30 operates in the saturation region, the output voltage may also be affected by other factors to generate fluctuations. For example, a dark current of a light receiving tube in the optocoupler 30 may cause fluctuation of an output voltage; in addition, the output voltage of the optocoupler 30 may be affected by factors such as the nonlinear characteristics of the device. In order to eliminate the influence of the voltage fluctuation output by the optocoupler 30 on the voltage detection accuracy, the embodiment sets the signal synchronization circuit 40 to synchronize the duty ratio of the voltage detection signal isolated and output by the optocoupler 30 in the above embodiment to a stable direct current power supply and then output the voltage detection signal to the power supply chip on the secondary side of the transformer, so that the accuracy of voltage detection can be further improved; the signal synchronization circuit 40 may be composed of electronic components such as resistors and transistors; for example, the signal synchronization circuit 40 is connected to a 5V dc power supply, and synchronizes the duty ratio of the voltage detection signal isolated from the optocoupler 30 to the dc power supply, so that a 0V-5V dc voltage is output to the power chip, corresponding to the 0V-220V voltage on the primary side of the transformer.
Referring to fig. 3, in an embodiment, the signal synchronization circuit 40 includes a first resistor R1, a second resistor R2, a third resistor R3, a first NPN transistor N1, and a first PNP transistor P1, where a first end of the first resistor R1 is connected to a first end of the second resistor R2, and is an input end of the signal synchronization circuit 40, a second end of the first resistor R1, a first end of the third resistor R3, a base of the first NPN transistor N1, and a base of the first PNP transistor P1 are interconnected, a second end of the second resistor R2, a second end of the third resistor R3, and a collector of the first PNP transistor P1 are grounded, an emitter of the first NPN transistor N1 is connected to an emitter of the first PNP transistor P1, and is an output end of the signal synchronization circuit 40, and a collector of the first NPN transistor N1 is connected to a dc power supply voltage V2.
In this embodiment, the second resistor R2 may perform a current limiting function to prevent damage to electronic components caused by excessive current in the circuit, and the first resistor R1 and the third resistor R3 may perform a voltage dividing function to divide the voltage output by the optocoupler 30, so that the voltage output to the first NPN triode N1 and the first PNP triode P1 will not exceed the maximum operating voltage thereof. Since the optocoupler 30 receives the PWM signal, the signal output to the signal synchronization circuit 40 is also a pulse signal having the same duty ratio, i.e., a high-level electrical signal and a low-level electrical signal of different time ratios; when the high-level electric signal is output to the bases of the first NPN triode N1 and the first PNP triode P1, the first NPN triode N1 is conducted, the first PNP triode P1 is turned off, and at the moment, the direct-current power supply voltage V2 connected to the collector of the first NPN triode N1 can be output to the power supply chip on the secondary side of the transformer and is the high-level electric signal; when the low-level electric signal is output to the bases of the first NPN triode N1 and the first PNP triode P1, the first NPN triode N1 is turned off and the first PNP triode P1 is turned on, and at this time, the electric signal output by the signal synchronization circuit 40 is pulled down to the ground, and is the low-level electric signal. So that the duty ratio of the pulse signal output by the optocoupler 30 can be synchronized to the direct current power supply voltage V2 connected to the collector of the first NPN triode N1, and the direct current power supply voltage V2 does not pass through the optocoupler 30 and cannot cause fluctuation of output voltage due to dark current of the light receiving tube; and the detection of the primary side voltage is more accurate because the detection is not influenced by factors such as nonlinear characteristics of the device. For example, a direct current power supply voltage V2 of 5V is connected, after the duty ratio of the pulse signal output by the synchronous optocoupler 30, the voltage output to the power chip on the secondary side of the transformer is changed to 0V-5V, which corresponds to the voltage of 0V-220V on the primary side of the transformer.
Referring to fig. 4, in an embodiment, the primary side voltage detection circuit further includes:
the input end of the rectifying circuit is used for being connected with the primary side voltage of the transformer, and the rectifying circuit is used for rectifying the primary side voltage and then outputting direct current voltage;
the input end of the voltage reduction circuit is connected with the output end of the rectifying circuit, and the voltage reduction circuit is used for carrying out voltage reduction conversion on the direct-current voltage output by the rectifying circuit and then outputting the direct-current voltage;
the input end of the first filter circuit is connected with the output end of the voltage reduction circuit, the output end of the first filter circuit is connected with the input end of the controller 10, and the first filter circuit is used for filtering the direct current voltage output by the voltage reduction circuit and outputting the direct current voltage to the controller 10.
In this embodiment, the primary side of the transformer in the charging device is usually connected to a power grid, and the power supply is connected to the power grid, and the controller 10 is damaged due to the excessively high voltage of the power supply, so a rectifying circuit, a voltage reducing circuit and a first filter circuit may be disposed between the ADC acquisition port of the controller 10 and the primary side of the transformer. The rectifying circuit can be composed of a plurality of rectifying diodes, rectifies an alternating current power supply of the mains supply into a direct current power supply and outputs the direct current power supply to the voltage reduction circuit. The voltage-reducing circuit may be composed of a plurality of resistors, and is configured to reduce the voltage of the high-voltage commercial power to the operating voltage range of the controller 10, and then output the voltage to the first filter circuit; the first filter circuit may be formed by electronic components such as a capacitor and a resistor, and filters the pulsating dc power outputted from the voltage-reducing circuit into a stable dc power, so that the ADC module of the controller 10 detects the voltage value more simply. The rectification circuit, the step-down circuit and the first filter circuit can convert the high-voltage alternating current power supply into the low-voltage stable direct current voltage, so that the controller 10 can better detect the voltage value. The specific circuit structures of the rectifying circuit, the step-down circuit and the first filter circuit may refer to fig. 4, and the scheme is not limited.
In an embodiment, the primary side voltage detection circuit further comprises:
and the input end of the second filter circuit is connected with the output end of the signal synchronization circuit 40, and the second filter circuit is used for filtering and outputting the pulse signal output by the signal synchronization circuit 40.
In this embodiment, the second filter circuit may be formed by electronic elements such as a resistor and a capacitor, and the signal synchronization circuit 40 synchronizes the duty ratio of the voltage detection signal to the dc power supply, and then outputs a pulse signal, which is also a pulsating dc signal, so that the second filter circuit needs to be provided, and filters the pulsating dc power supply into a stable dc power supply, and then outputs the stable dc power supply to a power chip on the secondary side of the transformer in the charging device through an output terminal OUT of the second filter circuit, so that the power chip obtains the voltage on the primary side of the transformer according to the dc power supply voltage V2, thereby selecting a corresponding charging voltage curve to charge the device to be charged.
Referring to fig. 3, in an embodiment, the second filter circuit includes a fourth resistor R4, a fifth resistor R5, a first capacitor C1, and a second capacitor C2, where a first end of the fourth resistor R4 is connected to the output end of the signal synchronization circuit 40, a second end of the fourth resistor R4, a first end of the fifth resistor R5, and a first end of the first capacitor C1 are interconnected, and a second end of the fifth resistor R5 is connected to a first end of the second capacitor C2 and is an output end of the second filter circuit, and a second end of the first capacitor C1 and a second end of the second capacitor C2 are grounded.
In this embodiment, the fourth resistor R4 and the first capacitor C1 may form a set of RC filter circuits, and the fifth resistor R5 and the second capacitor C2 may form another set of RC filter circuits, and the pulse signal output by the signal synchronization circuit 40 is filtered by the two sets of filter circuits, so that the pulsating dc power supply is filtered into a stable dc power supply. The two groups of RC filter circuits can further filter high-frequency components in the pulse signals, so that a stronger filter effect is achieved, a specific filter circuit structure can be set according to actual conditions, and the scheme is not limited.
In one embodiment, the current adjusting element 20 is an adjustable resistor.
In this embodiment, the current adjusting element 20 can select an adjustable resistor, and as can be seen from the above description, the resistance value of the resistor is determined according to the minimum operating current of the saturation region of the optocoupler 30 and the high level voltage of the PWM signal outputted by the controller 10, so that the current can be adjusted more conveniently by using the adjustable resistor as the current adjusting element 20.
In an embodiment, the primary side voltage detection circuit further comprises:
the output end of the temperature detection circuit is connected with the temperature input end of the controller 10, the temperature detection circuit is used for detecting the ambient temperature and outputting a temperature detection signal to the controller 10, and the controller 10 is further used for controlling the primary side voltage detection circuit to stop working when the ambient temperature value detected by the temperature detection signal exceeds a temperature threshold value.
In this embodiment, the temperature detection circuit may be formed by electronic elements such as a temperature switch and a resistor, for example, the temperature switch is turned off when the temperature is set to be low, and turned on when the ambient temperature exceeds a temperature threshold, so that different electrical signals can be output to the controller 10, and the temperature threshold may be the highest working temperature that any electronic device in the primary side voltage detection circuit can bear; if the high-level electric signal represents that the temperature is normal and the low-level electric signal represents that the temperature is too high, the controller 10 can control the primary voltage detection circuit to stop working according to the low-level electric signal. The temperature detection circuit can play a role in over-temperature protection on the whole primary side voltage detection circuit.
The invention also provides a charging device which comprises a transformer and the primary side voltage detection circuit. The specific structure of the primary side voltage detection circuit refers to the above embodiments, and since the charging device adopts all the technical solutions of all the embodiments, the charging device has at least all the beneficial effects brought by the technical solutions of the embodiments, and will not be described in detail herein. In an embodiment, the charging device may be a power adapter or a charging pile, and may be applied to an electric vehicle or other electric equipment.
In an embodiment, the charging device further includes a power chip, the controller 10 is further electrically connected to the power chip, and the controller 10 is further configured to output an operation enable signal to the power chip when the operation voltage is accessed, so that the power chip starts to operate.
In this embodiment, the charging device further includes a power chip, where the power chip is connected to the secondary side of the transformer, and the power chip may select a corresponding charging voltage curve according to the detected primary side voltage value, and convert the voltage output from the secondary side of the transformer to charge the electric device. In order to save energy consumption, when the electric device is not charged, devices such as a power chip and the like in the charging device can keep a dormant state, when the primary side voltage detection circuit is connected with the working voltage and starts to detect the primary side voltage, the charging device is connected with the mains supply, so that the controller 10 in the primary side voltage detection circuit can output a working enabling signal to the power chip at the moment, so that the power chip starts to work, and other devices in the charging device can also start to work to charge the electric device.
The invention also provides an electric vehicle comprising the charging device. The specific structure of the charging device refers to the above embodiments, and since the electric vehicle adopts all the technical solutions of all the embodiments, the charging device at least has all the beneficial effects brought by the technical solutions of the embodiments, and will not be described in detail herein. It can be understood that the electric vehicle generally has a longer charging time, and if the voltage fluctuation of the power grid is larger or more frequent during charging, the charging device cannot charge the electric vehicle by using the corresponding charging voltage curve, which easily causes the service life of the charging device to be reduced or a safety accident to occur. The change condition of the primary side voltage can be accurately detected through the primary side voltage detection circuit in the charging device, so that the charging device can select a corresponding charging voltage curve to charge the electric vehicle.
The foregoing description is only of the optional embodiments of the present invention, and is not intended to limit the scope of the invention, and all the equivalent structural changes made by the description of the present invention and the accompanying drawings or direct/indirect application in other related technical fields are included in the scope of the invention.

Claims (10)

1. A primary voltage detection circuit for use with a charging device having a transformer, the primary voltage detection circuit comprising:
the voltage input end of the controller is used for accessing the primary side voltage of the transformer and outputting a voltage detection signal corresponding to the duty ratio according to the primary side voltage;
the positive electrode of the transmitting end of the optical coupler is connected with the output end of the controller, and the optical coupler is used for isolating and outputting the voltage detection signal;
the current adjusting element is arranged between the output end of the controller and the positive electrode of the transmitting end of the optocoupler in series, and is used for adjusting the current output to the positive electrode of the transmitting end of the optocoupler so that the optocoupler works in a saturation region.
2. The primary-side voltage detection circuit of claim 1, wherein the primary-side voltage detection circuit further comprises:
the input end of the signal synchronization circuit is connected with the emitter of the receiving end of the optocoupler, the power end of the signal synchronization circuit is used for being connected with a direct-current power supply, and the signal synchronization circuit is used for outputting pulse signals with the same duty ratio as the voltage detection signals according to the voltage detection signals.
3. The primary side voltage detection circuit of claim 2, wherein the signal synchronization circuit comprises a first resistor, a second resistor, a third resistor, a first NPN triode, and a first PNP triode, wherein a first end of the first resistor is connected to a first end of the second resistor and is an input end of the signal synchronization circuit, wherein a second end of the first resistor, a first end of the third resistor, a base of the first NPN triode, and a base of the first PNP triode are interconnected, wherein a second end of the second resistor, a second end of the third resistor, and a collector of the first PNP triode are grounded, wherein an emitter of the first NPN triode is connected to an emitter of the first PNP triode and is an output end of the signal synchronization circuit, and wherein a collector of the first NPN triode is connected to a dc power supply voltage.
4. The primary-side voltage detection circuit of claim 2, wherein the primary-side voltage detection circuit further comprises:
the input end of the second filter circuit is connected with the output end of the signal synchronization circuit, and the second filter circuit is used for filtering the pulse signal output by the signal synchronization circuit and outputting the pulse signal.
5. The primary-side voltage detection circuit of claim 4, wherein the second filter circuit comprises a fourth resistor, a fifth resistor, a first capacitor, and a second capacitor, the first end of the fourth resistor is connected to the output terminal of the signal synchronization circuit, the second end of the fourth resistor, the first end of the fifth resistor, and the first end of the first capacitor are interconnected, the second end of the fifth resistor is connected to the first end of the second capacitor, and is the output terminal of the second filter circuit, and the second ends of the first capacitor and the second capacitor are grounded.
6. The primary side voltage detection circuit of claim 1 wherein the current regulating element is an adjustable resistor.
7. The primary-side voltage detection circuit of claim 1, wherein the primary-side voltage detection circuit further comprises:
the input end of the rectifying circuit is used for being connected with the primary side voltage of the transformer, and the rectifying circuit is used for rectifying the primary side voltage and then outputting direct current voltage;
the input end of the voltage reduction circuit is connected with the output end of the rectifying circuit, and the voltage reduction circuit is used for carrying out voltage reduction conversion on the direct-current voltage output by the rectifying circuit and then outputting the direct-current voltage;
the input end of the first filter circuit is connected with the output end of the voltage reduction circuit, the output end of the first filter circuit is connected with the input end of the controller, and the first filter circuit is used for filtering the direct current voltage output by the voltage reduction circuit and outputting the direct current voltage to the controller.
8. The primary-side voltage detection circuit of claim 1, wherein the primary-side voltage detection circuit further comprises:
the temperature detection circuit is connected with the temperature input end of the controller, and is used for detecting the ambient temperature and outputting a temperature detection signal to the controller, and the controller is also used for controlling the primary side voltage detection circuit to stop working when the ambient temperature value detected by the temperature detection signal exceeds a temperature threshold value.
9. A charging device comprising a transformer and a primary voltage detection circuit as claimed in any one of claims 1 to 8.
10. An electric vehicle comprising the charging device according to claim 9.
CN202310856490.4A 2023-07-13 2023-07-13 Primary side voltage detection circuit, charging device and electric vehicle Active CN116577540B (en)

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