CN109302069B - Electric automobile charger and resonant circuit for improving current stability thereof - Google Patents
Electric automobile charger and resonant circuit for improving current stability thereof Download PDFInfo
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- CN109302069B CN109302069B CN201810994906.8A CN201810994906A CN109302069B CN 109302069 B CN109302069 B CN 109302069B CN 201810994906 A CN201810994906 A CN 201810994906A CN 109302069 B CN109302069 B CN 109302069B
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- 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
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33507—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters
- H02M3/33523—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of the output voltage or current, e.g. flyback converters with galvanic isolation between input and output of both the power stage and the feedback loop
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/10—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers
- H02H7/12—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers
- H02H7/1213—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for converters; for rectifiers for static converters or rectifiers for DC-DC 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
- H02M3/00—Conversion of dc power input into dc power output
- H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
- H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
- H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
- H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
- H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Dc-Dc Converters (AREA)
- Charge And Discharge Circuits For Batteries Or The Like (AREA)
Abstract
The invention discloses a resonance circuit for improving current stability, which comprises: the circuit comprises a rectangular wave generating circuit, a resonant tank circuit, a voltage transformation circuit and a rectifying circuit; the first end of the filter capacitor is connected with the first output end of the rectifying circuit, the common end of the filter capacitor is connected with the first end of the load, the second end of the filter capacitor is connected with the second output end of the rectifying circuit, and the common end of the filter capacitor is connected with the second end of the load; the first current sampling circuit is arranged between the rectifying circuit and the filter capacitor; the second current sampling circuit is arranged between the filter capacitor and the load; and the detection control device is used for determining whether the system is in a hiccup mode, if so, the output current of the second current sampling circuit is adopted for feedback control, and otherwise, the output current of the first current sampling circuit is adopted for feedback control. By applying the scheme provided by the invention, stable feedback current can be obtained when the system is in a hiccup mode. The invention also discloses a charger for the electric automobile, which has corresponding effects.
Description
Technical Field
The invention relates to the technical field of power converters, in particular to an electric vehicle charger and a resonant circuit for improving current stability of the electric vehicle charger.
Background
The resonance transformation technology adopted by the series resonance converter is a resonance circuit which realizes the stabilization of output voltage by controlling the switching frequency, can realize the zero-voltage switching-on of a primary side main MOS switch and the zero-current switching-off of a secondary side rectifier diode, can reduce the switching loss of a power supply and improve the efficiency and the power density of the power converter by the soft switching technology.
The LLC resonant circuit is one of the common resonant converting circuits, and when the load changes, the voltage dividing ratio of the load can be changed by adjusting the operating frequency of the LLC resonant circuit, thereby adjusting the voltage of the load. Referring to fig. 1, a characteristic curve of a dc voltage gain of the LLC resonant circuit is shown, where when a switching frequency of an MOS transistor in the LLC resonant circuit changes, the dc gain changes accordingly, that is, the load voltage is adjusted. It can be seen that when the load is small, the switching frequency of the MOS transistor needs to be increased to reduce the gain. However, the switching frequency cannot be raised infinitely due to the limitation of devices such as MOS transistors, and at this time, in order to achieve a lower gain, the system enters a hiccup mode, that is, the drive of the LLC resonant circuit is intermittently pulsed.
In the prior art, a current sampling circuit is arranged between an output end of a rectifying circuit and a filter capacitor in a resonant conversion circuit, and the output current of the current sampling circuit is used for performing closed-loop control on a system. When the system normally operates, namely in a non-hiccup mode, the current sampling circuit arranged at the position can quickly reflect the output current of the system, so that the feedback circuit can obtain quick response, and the bandwidth and the protection response of a current loop can be improved. However, when the load is low and the system is in the hiccup mode, the current signal sampled here will be an unstable steamed bread wave, and since the detected current is unstable, it is not favorable for the stable operation of the system to use it as the feedback current.
In summary, how to obtain stable feedback current when the system is in the hiccup mode is a technical problem that needs to be solved urgently by those skilled in the art.
Disclosure of Invention
The invention aims to provide an electric vehicle charger and a resonant circuit thereof for improving current stability so as to obtain stable feedback current when a system is in a hiccup mode.
In order to solve the technical problems, the invention provides the following technical scheme:
a resonant circuit for improved current stability, comprising:
the circuit comprises a rectangular wave generating circuit, a resonant tank circuit, a voltage transformation circuit and a rectifying circuit;
the rectangular wave generating circuit is connected with the resonant tank circuit, the resonant tank circuit is connected with the voltage transformation circuit, and the voltage transformation circuit is connected with the rectifying circuit;
the first end of the filter capacitor is connected with the first output end of the rectifying circuit, the common end of the filter capacitor is connected with the first end of the load, the second end of the filter capacitor is connected with the second output end of the rectifying circuit, and the common end of the filter capacitor is connected with the second end of the load;
the first current sampling circuit is arranged between the rectifying circuit and the filter capacitor;
a second current sampling circuit disposed between the filter capacitor and the load;
and the detection control device is used for determining whether the system is in a hiccup mode, if so, the output current of the second current sampling circuit is adopted for feedback control, and otherwise, the output current of the first current sampling circuit is adopted for feedback control.
Preferably, the detection control means includes:
the voltage sampling circuit is connected with the first end of the load at the first end and connected with the second end of the load at the second end;
the selection circuit is connected with the voltage sampling circuit, the first current sampling circuit and the second current sampling circuit and is used for determining whether a system is in a hiccup mode or not according to the output voltage of the voltage sampling circuit and a preset rule, if so, the output current of the second current sampling circuit is output to a feedback control device to enable the feedback control device to perform feedback control, and otherwise, the output current of the first current sampling circuit is output to the feedback control device to enable the feedback control device to perform feedback control;
the feedback control device.
Preferably, the preset rule is as follows: determining that the system is in a non-hiccup mode when the output voltage of the voltage sampling circuit is above a first threshold, determining that the system is in a hiccup mode when the output voltage of the voltage sampling circuit is below a second threshold, and determining that the system is in a mode that was last determined before when the output voltage of the voltage sampling circuit is between the first threshold and the second threshold, wherein the second threshold is less than the first threshold.
Preferably, the method further comprises the following steps:
and the first end of the ripple current processing circuit is connected with the first end of the load, and the second end of the ripple current processing circuit is connected with the second end of the load.
Preferably, the ripple current processing circuit includes:
the first resistor is connected with the first end of the load at the first end, and connected with the first end of the first capacitor at the second end;
the second end of the first capacitor is connected with the second end of the load.
Preferably, the rectangular wave generating circuit is a full-bridge rectangular wave generating circuit.
Preferably, the rectifier circuit is a bridge type full-control rectifier circuit, and the resonant tank circuit is an LLC resonant tank.
Preferably, the rectangular wave generating circuit includes a first rectangular wave generating circuit and a second rectangular wave generating circuit, the resonant tank circuit includes a first resonant tank circuit and a second resonant tank circuit, and the transforming circuit includes a first transforming circuit and a second transforming circuit; the rectifying circuit comprises a first rectifying circuit and a second rectifying circuit;
a first output end of the first rectangular wave generating circuit is connected with a first input end of the first resonant tank circuit, and a second output end of the first rectangular wave generating circuit is connected with a second input end of the first resonant tank circuit;
a first output end of the second rectangular wave generating circuit is connected with a first input end of the second resonant tank circuit, and a second output end of the second rectangular wave generating circuit is connected with a second input end of the second resonant tank circuit;
a first output end of the first resonant tank circuit is connected with a first input end of the first voltage transformation circuit, and a second output end of the first resonant tank circuit is connected with a second input end of the first voltage transformation circuit;
the first output end of the second resonance tank circuit is connected with the first input end of the second voltage transformation circuit, and the second output end of the second resonance tank circuit is connected with the second input end of the second voltage transformation circuit;
the first output end of the first voltage transformation circuit is connected with the first input end of the first rectifying circuit, and the second output end of the first voltage transformation circuit is connected with the second input end of the first rectifying circuit;
the first output end of the second voltage transformation circuit is connected with the first input end of the second rectifying circuit, and the second output end of the second voltage transformation circuit is connected with the second input end of the second rectifying circuit;
the positive electrode of the power supply in the second rectangular wave generating circuit is connected with the negative electrode of the power supply in the first rectangular wave generating circuit;
the first output end of the second rectifying circuit is connected with the first output end of the first rectifying circuit, and the common end of the second rectifying circuit is used as the first output end of the rectifying circuit; and the second output end of the second rectifying circuit is connected with the second output end of the first rectifying circuit, and the common end of the second rectifying circuit is used as the second output end of the rectifying circuit.
Preferably, the filter capacitor is an electrolytic capacitor.
An electric vehicle charger comprises the resonance circuit for improving the current stability.
The technical scheme provided by the embodiment of the invention comprises the following steps: the circuit comprises a rectangular wave generating circuit, a resonant tank circuit, a voltage transformation circuit and a rectifying circuit; the rectangular wave generating circuit is connected with the resonant tank circuit, the resonant tank circuit is connected with the voltage transformation circuit, and the voltage transformation circuit is connected with the rectifying circuit; the first end of the filter capacitor is connected with the first output end of the rectifying circuit, the common end of the filter capacitor is connected with the first end of the load, the second end of the filter capacitor is connected with the second output end of the rectifying circuit, and the common end of the filter capacitor is connected with the second end of the load; the first current sampling circuit is arranged between the rectifying circuit and the filter capacitor; the second current sampling circuit is arranged between the filter capacitor and the load; and the detection control device is used for determining whether the system is in a hiccup mode, if so, the output current of the second current sampling circuit is adopted for feedback control, and otherwise, the output current of the first current sampling circuit is adopted for feedback control.
The current sampling circuit comprises a first current sampling circuit arranged between a filter capacitor and a rectifying circuit and a second current sampling circuit arranged between the filter capacitor and a load. Because the sampling current obtained by the second current sampling circuit passes through the filter capacitor, the current signal acquired by the system is a stable and smooth direct current signal even when the system is in a hiccup mode. Therefore, when determining that the system is in the hiccup mode, the output current of the second current sampling circuit is adopted for feedback control, so that the system stability is facilitated, and the output current of the second current sampling circuit is stable feedback current. And when the system is in a non-hiccup mode, the output current of the first current sampling circuit is adopted for feedback control, so that the feedback circuit in the mode still has the advantage of quick response. Therefore, the scheme of the application can obtain stable feedback current when the system is in the hiccup mode.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a DC voltage gain characteristic curve of an LLC resonant circuit;
FIG. 2 is a schematic diagram of a resonant circuit for improving current stability according to the present invention;
fig. 3 is another structural diagram of the resonant circuit for improving current stability according to the present invention.
Detailed Description
The core of the invention is to provide a resonant circuit for improving the current stability, which can obtain stable feedback current when the system is in a hiccup mode.
In order that those skilled in the art will better understand the disclosure, the invention will be described in further detail with reference to the accompanying drawings and specific embodiments. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 2, fig. 2 is a schematic structural diagram of a resonant circuit for improving current stability according to the present invention, including:
a rectangular wave generating circuit 10, a resonant tank circuit 20, a transformer circuit 30 and a rectifier circuit 40.
Specifically, the rectangular wave generating circuit 10 is connected to the resonant tank circuit 20, the resonant tank circuit 20 is connected to the transformer circuit 30, and the transformer circuit 30 is connected to the rectifier circuit 40.
The rectangular wave generating circuit 10 may be a full-bridge rectangular wave generating circuit or a half-bridge rectangular wave generating circuit, and may be set and selected according to actual conditions without affecting the implementation of the present invention. The half-bridge rectangular wave generating circuit needs fewer switching devices, and the corresponding driving circuit is simpler in design and lower in cost. The full-bridge rectangular wave generating circuit has a more complex design but has higher output power, and is particularly suitable for the full-bridge rectangular wave generating circuit in a high-power circuit such as an electric vehicle charger. In addition, the type of the switching tube in the rectangular wave generating circuit 10 can also be selected according to actual needs.
The resonant tank circuit 20 may be a series resonant tank circuit, such as a common LC series resonant tank, an LLC series resonant tank, or a parallel resonant tank circuit, without affecting the implementation of the present invention. It should be noted that, the LLC series resonant tank has a low switching loss, a high efficiency near the resonant point, and is suitable for high-frequency and high-power applications, and therefore, in the electric vehicle charger of the present application, the LLC series resonant tank generally needs to be selected. LLC series resonance tank can be generally used by resonance capacitor CrResonant inductance LrAnd an excitation inductance LmIt is shown, but should be noted that the excitation is due toMagnetic inductance LmIs the transformer circuit 30, is an equivalent inductance, and therefore in the schematic diagram of a part of the LLC resonant circuit, the excitation inductance of the LLC resonant tank therein is not shown.
The transformer circuit 30 may be a transformer, and the number of turns of the primary winding and the secondary winding may be set according to actual needs. The rectifying circuit 40 may also include various forms such as a bridge rectifier circuit, a zero rectifier circuit, an uncontrollable rectifier circuit, a half-controlled rectifier circuit, etc. In one embodiment, the rectifier circuit 40 may be a bridge type fully-controlled rectifier circuit with low output voltage ripple, which can improve the utilization rate of the transformer. The type of the switching tube used in the rectifying circuit 40 can also be selected according to the requirement.
The first terminal of the filter capacitor C1 is connected to the first output terminal of the rectifier circuit 40, the common terminal thereof is connected to the first terminal of the load, the second terminal of the filter capacitor C1 is connected to the second output terminal of the rectifier circuit 40, and the common terminal thereof is connected to the second terminal of the load.
The specific capacitance of the filter capacitor C1 can be set according to actual needs, and in a case where the input voltage is relatively high, for example, in an electric vehicle charger, the filter capacitor C1 can be an electrolytic capacitor with a large capacitance.
And a first current sampling circuit 50 disposed between the rectifying circuit 40 and the filter capacitor C1.
Specifically, the first sampling terminal of the first current sampling circuit 50 may be connected to the first output terminal of the rectifying circuit 40, and the second sampling terminal may be connected to the first terminal of the filter capacitor C1, or the first sampling terminal thereof may be connected to the second output terminal of the rectifying circuit 40, and the second sampling terminal may be connected to the second terminal of the filter capacitor C1. Generally, the first sampling terminal of the first current sampling circuit 50 is connected to the second output terminal of the rectifying circuit 40, and the second sampling terminal is connected to the second terminal of the filter capacitor C1, where the second output terminal of the rectifying circuit 40 refers to the terminal connected to the negative electrode of the load, which is the connection mode in fig. 3.
Since the first current sampling circuit 50 is disposed between the rectifying circuit 40 and the filter capacitor C1, the sampled current is the output current of the rectifying circuit 40, and the current can quickly reflect the output current of the system, and the current is used as the feedback current in the closed-loop control, which also has the advantage of quick response.
And a second current sampling circuit 60 disposed between the filter capacitor C1 and the load.
Specifically, the first sampling terminal of the second current sampling circuit 60 may be connected to the first terminal of the filter capacitor C1, and the second sampling terminal may be connected to the first terminal of the load, or the first sampling terminal thereof may be connected to the second terminal of the filter capacitor C1, and the second sampling terminal may be connected to the second terminal of the load. In general, the first sampling terminal of the second current sampling circuit 60 is connected to the second terminal of the filter capacitor C1, and the second sampling terminal is connected to the second terminal of the load, where the second terminal of the load is the negative terminal of the load, and the current obtained here is more stable, which is the connection manner in fig. 3.
Since the second current sampling circuit 60 is disposed between the load and the filter capacitor C1, the sampled current is the current after the output current of the rectifying circuit 40 passes through the filter capacitor C1, and the sampled current is a smooth direct current regardless of whether the system is in the hiccup mode, and the current is used as a feedback current in the closed-loop control, which is beneficial to the system stability. The configurations of the first current sampling circuit 50 and the second current sampling circuit 60 can be set and adjusted according to actual needs, and the implementation of the present invention is not affected. For example, a differential current sampling circuit is adopted to reduce the influence of external disturbance on the detection result.
And the detection control device is used for determining whether the system is in a hiccup mode, if so, the output current of the second current sampling circuit 60 is used for feedback control, and otherwise, the output current of the first current sampling circuit 50 is used for feedback control.
The detection control device serves as a closed control element of the system and is not shown in fig. 2. The detection control means may determine whether the system is in the hiccup mode, for example, the detection control means may determine whether the system is in the hiccup mode according to the magnitude of the output current of the second current sampling circuit 60. Specifically, the hiccup mode may be determined by an associated logic determination circuit, such as a schmitt trigger circuit.
The detection control device is connected with the first current sampling circuit 50 and the second current sampling circuit 60, and when the system is determined to be in the hiccup mode, the detection control device adopts the output current of the second current sampling circuit 60 to perform feedback control, and correspondingly adopts the output current of the first current sampling circuit 50 to perform feedback control when the system is determined to be in the non-hiccup mode.
The resonance circuit for improving the current stability provided by the invention comprises: the circuit comprises a rectangular wave generating circuit, a resonant tank circuit, a voltage transformation circuit and a rectifying circuit; the rectangular wave generating circuit is connected with the resonant tank circuit, the resonant tank circuit is connected with the voltage transformation circuit, and the voltage transformation circuit is connected with the rectifying circuit; the first end of the filter capacitor is connected with the first output end of the rectifying circuit, the common end of the filter capacitor is connected with the first end of the load, the second end of the filter capacitor is connected with the second output end of the rectifying circuit, and the common end of the filter capacitor is connected with the second end of the load; the first current sampling circuit is arranged between the rectifying circuit and the filter capacitor; the second current sampling circuit is arranged between the filter capacitor and the load; and the detection control device is used for determining whether the system is in a hiccup mode, if so, the output current of the second current sampling circuit is adopted for feedback control, and otherwise, the output current of the first current sampling circuit is adopted for feedback control.
The current sampling circuit comprises a first current sampling circuit arranged between a filter capacitor and a rectifying circuit and a second current sampling circuit arranged between the filter capacitor and a load. Because the sampling current obtained by the second current sampling circuit passes through the filter capacitor, the current signal acquired by the system is a stable and smooth direct current signal even when the system is in a hiccup mode. Therefore, when determining that the system is in the hiccup mode, the output current of the second current sampling circuit is adopted for feedback control, so that the system stability is facilitated, and the output current of the second current sampling circuit is stable feedback current. And when the system is in a non-hiccup mode, the output current of the first current sampling circuit is adopted for feedback control, so that the feedback circuit in the mode still has the advantage of quick response. Therefore, the scheme of the application can obtain stable feedback current when the system is in the hiccup mode.
In one embodiment of the present invention, the detection control means includes:
a voltage sampling circuit 70 having a first terminal connected to the first terminal of the load and a second terminal connected to the second terminal of the load;
the selection circuit is connected with the voltage sampling circuit 70, the first current sampling circuit 50 and the second current sampling circuit 60 and is used for determining whether the system is in a hiccup mode or not according to the output voltage of the voltage sampling circuit 70 and a preset rule, if so, the output current of the second current sampling circuit 60 is output to the feedback control device to enable the feedback control device to perform feedback control, and otherwise, the output current of the first current sampling circuit 50 is output to the feedback control device to enable the feedback control device to perform feedback control;
a feedback control device.
In this embodiment, referring to fig. 3, it is determined whether the system is in the hiccup mode by the output voltage of the voltage sampling circuit 70, the first terminal of the voltage sampling circuit 70 is connected to the first terminal of the load, the second terminal is connected to the second terminal of the load, and the output is the load voltage.
The feedback control means and the selection circuit are not shown in fig. 3. The selection circuit is connected to the voltage sampling circuit 70, and can determine whether the system is in the hiccup mode according to the output voltage of the voltage sampling circuit 70 and a preset rule. For example, when the output voltage is higher than the preset value, indicating that the load is large, the selection circuit may determine that the system is in the non-hiccup mode, and when the output voltage is lower than the preset value, indicating that the load is small, the selection circuit may determine that the system is in the hiccup mode, and the size of the preset value may also be set and adjusted according to an actual circuit.
When the selection circuit determines that the system is in a non-hiccup mode, the selection circuit outputs the output current of the first current sampling circuit 50 to the feedback control device, correspondingly, when the selection circuit determines that the system is in the hiccup mode, the selection circuit outputs the output current of the second current sampling circuit 60 to the feedback control device, and the feedback control device performs feedback control according to the received corresponding electric signal.
In one embodiment of the present invention, the preset rule is: when the output voltage of the voltage sampling circuit 70 is higher than a first threshold value, it is determined that the system is in a non-hiccup mode, when the output voltage of the voltage sampling circuit 70 is lower than a second threshold value, it is determined that the system is in a hiccup mode, and when the output voltage of the voltage sampling circuit 70 is between the first threshold value and the second threshold value, it is determined that the system is in a mode which is determined last time before.
Considering the single threshold setting, if the output voltage of the voltage sampling circuit 70 fluctuates around the threshold, the system mode determined by the selection circuit will be switched continuously, which is not favorable for system stability. Therefore, the setting of the dual threshold is adopted in this embodiment. For example, the first threshold is 305V, the second threshold is 300V, and when the output voltage of the voltage sampling circuit 70 is higher than 305V, the selection circuit determines that the system is in the non-hiccup mode. If the output voltage of the voltage sampling circuit 70 drops, for example to 303V, the selection circuit will still determine that the system is in a non-hiccup mode. If the output voltage of the voltage sampling circuit 70 continues to decrease, for example to 297V, the selection circuit determines that the system is in hiccup mode. Assuming that the output voltage of the voltage sampling circuit 70 rises to 301V later, the selection circuit will still determine that the system is in hiccup mode. The setting of the double thresholds is beneficial to the stability of the system. The setting of the second threshold value and the setting of the first threshold value may be determined by experimental data and theoretical calculation.
In the above embodiment, the voltage sampling circuit 70 is provided at the load side, and the output voltage is the load voltage, but in other embodiments, the voltage sampling circuit 70 may be provided at another position of the resonant circuit, and may reflect the system operation mode, for example, may be provided at the output terminal of the rectangular wave generating circuit 10, and in this case, the relevant threshold value in the selection circuit may be adjusted appropriately.
In addition, in the foregoing solution, the selection circuit is adopted to obtain the output voltage of the voltage sampling circuit 70, and then it is determined whether the system is in the hiccup mode according to a preset rule, in other embodiments, the hiccup mode may be determined based on the current or the switching frequency. Specifically, the selection circuit may obtain the output current of the second current sampling circuit 60, and determine whether the system is in the hiccup mode according to the magnitude of the current, and of course, similar to the preset rule, when determining the magnitude of the current, a single threshold may be used as the determination reference, or a double threshold may be used as the determination reference, and the foregoing description may be referred to, and the description is not repeated here. The selection circuit can also obtain the switching frequency of the resonant circuit, and determine whether the system is in the hiccup mode based on the switching frequency, for example, when the switching frequency reaches a preset highest frequency and the duration reaches a preset duration, the selection circuit can determine that the system is in the hiccup mode.
In one embodiment of the present invention, the method further comprises:
and the first end of the ripple current processing circuit is connected with the first end of the load, and the second end of the ripple current processing circuit is connected with the second end of the load.
In this embodiment, a ripple current processing circuit may be further added to further reduce the output ripple after the current output from the rectifying circuit 40 has ripple and is processed by the filter capacitor C1. Specifically, the first terminal of the ripple current processing circuit may be connected to the first terminal of the load, and the second terminal of the ripple current processing circuit may be connected to the second terminal of the load. The specific structure of the ripple current processing circuit can be set according to actual needs, for example, a circuit based on a filtering method, a circuit based on a two-way parallel superposition method, and the like.
In one embodiment, referring to fig. 3, the ripple current processing circuit includes:
a first resistor R1 having a first end connected to a first end of the load and a second end connected to a first end of the first capacitor C2; and a first capacitor C2 having a second terminal connected to the second terminal of the load.
The ripple current processing circuit in the implementation mode is simple in structure and easy to implement. It should be noted that in this embodiment, the ripple frequency characteristic needs to be obtained according to an actual situation, so as to determine a more accurate resistance value and capacitance value, so as to avoid mixing new ripple or noise, and to increase the output ripple.
In one embodiment of the present invention, referring to fig. 3, the rectangular wave generating circuit 10 includes a first rectangular wave generating circuit 11 and a second rectangular wave generating circuit 12, the resonant tank circuit 20 includes a first resonant tank circuit 21 and a second resonant tank circuit 22, and the transforming circuit 30 includes a first transforming circuit 31 and a second transforming circuit 32; the rectifying circuit 40 includes a first rectifying circuit 41 and a second rectifying circuit 42;
a first output end of the first rectangular wave generating circuit 11 is connected with a first input end of the first resonant tank circuit 21, and a second output end is connected with a second input end of the first resonant tank circuit 21;
a first output end of the second rectangular wave generating circuit 12 is connected with a first input end of the second resonant tank circuit 22, and a second output end is connected with a second input end of the second resonant tank circuit 22;
a first output end of the first resonant tank circuit 21 is connected with a first input end of the first voltage transformation circuit 31, and a second output end is connected with a second input end of the first voltage transformation circuit 31;
a first output end of the second resonant tank circuit 22 is connected with a first input end of the second voltage transformation circuit 32, and a second output end is connected with a second input end of the second voltage transformation circuit 32;
a first output end of the first voltage transformation circuit 31 is connected with a first input end of the first rectification circuit 41, and a second output end is connected with a second input end of the first rectification circuit 41;
a first output end of the second voltage transformation circuit 32 is connected with a first input end of the second rectification circuit 42, and a second output end is connected with a second input end of the second rectification circuit 42;
the positive electrode of the power supply in the second rectangular wave generating circuit 12 is connected with the negative electrode of the power supply in the first rectangular wave generating circuit 11;
a first output terminal of the second rectifying circuit 42 is connected to a first output terminal of the first rectifying circuit 41, and a common terminal thereof serves as a first output terminal of the rectifying circuit 40; a second output terminal of the second rectifying circuit 42 is connected to a second output terminal of the first rectifying circuit 41, and a common terminal thereof serves as a second output terminal of the rectifying circuit 40.
This embodiment is generally suitable for applications where the voltage level of the system is large. Specifically, the front stage is designed in a serial manner, that is, the first rectangular wave generating circuit 11 and the second rectangular wave generating circuit 12 are designed in a serial manner, and the positive electrode of the power supply in the second rectangular wave generating circuit 12 is connected with the negative electrode of the power supply in the first rectangular wave generating circuit 11. Normally, the power supply voltage in the second rectangular wave generation circuit 12 is equal to the power supply voltage in the first rectangular wave generation circuit 11. In this manner, the power supply voltage in the first rectangular wave generating circuit 11 is equal to the power supply voltage in the second rectangular wave generating circuit 12 and is equal to half the power supply voltage in the single-power rectangular wave generating circuit 10, compared to the design of the single-power rectangular wave generating circuit 10. Since the level of the power supply voltage in the rectangular wave generating circuit 10 is lowered, it is advantageous to improve the safety of the system.
The latter stage is designed in parallel, specifically, the first rectangular wave generating circuit 11, the first resonant tank circuit 21, the first transformer circuit 31 and the first rectifying circuit 41 are connected in sequence, the second rectangular wave generating circuit 12, the second resonant tank circuit 22, the second transformer circuit 32 and the second rectifying circuit 42 are also connected in sequence, the first output end of the second rectifying circuit 42 is connected with the first output end of the first rectifying circuit 41, the common end thereof is used as the first output end of the rectifying circuit 40, the second output end of the second rectifying circuit 42 is connected with the second output end of the first rectifying circuit 41, and the common end thereof is used as the second output end of the rectifying circuit 40. Such a design does not lower the level of the output voltage of the system compared to the design of the single-power rectangular wave generation circuit 10. Therefore, in the embodiment of the present application, the level of the output voltage of the system is not affected on the premise that the level of the power supply voltage in the rectangular wave generating circuit 10 is reduced and the system safety is improved. It should be noted that the structures and related parameters of the first rectangular wave generating circuit 11, the first resonant tank circuit 21, the first voltage transforming circuit 31 and the first rectifying circuit 41 are generally the same as those of the second rectangular wave generating circuit 12, the second resonant tank circuit 22, the second voltage transforming circuit 32 and the second rectifying circuit 42, so as to reduce system harmonics and facilitate stable operation of the system.
Corresponding to the above embodiment of the resonant circuit for improving the current stability, the embodiment of the present invention further provides an electric vehicle charger, which may include the resonant circuit for improving the current stability in any of the above embodiments, and the description is not repeated here.
It is further noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
Those of skill would further appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of their functionality in order to clearly illustrate this interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the implementation. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.
The principle and the implementation of the present invention are explained in the present application by using specific examples, and the above description of the embodiments is only used to help understanding the technical solution and the core idea of the present invention. It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.
Claims (10)
1. A resonant circuit for improving current stability, comprising:
the circuit comprises a rectangular wave generating circuit, a resonant tank circuit, a voltage transformation circuit and a rectifying circuit;
the rectangular wave generating circuit is connected with the resonant tank circuit, the resonant tank circuit is connected with the voltage transformation circuit, and the voltage transformation circuit is connected with the rectifying circuit;
the first end of the filter capacitor is connected with the first output end of the rectifying circuit, the common end of the filter capacitor is connected with the first end of the load, the second end of the filter capacitor is connected with the second output end of the rectifying circuit, and the common end of the filter capacitor is connected with the second end of the load;
the first current sampling circuit is arranged between the rectifying circuit and the filter capacitor;
a second current sampling circuit disposed between the filter capacitor and the load;
and the detection control device is used for determining whether the system is in a hiccup mode, if so, the output current of the second current sampling circuit is adopted for feedback control, and otherwise, the output current of the first current sampling circuit is adopted for feedback control.
2. The resonant circuit for improving current stability according to claim 1, wherein the detection control means comprises:
the voltage sampling circuit is connected with the first end of the load at the first end and connected with the second end of the load at the second end;
the selection circuit is connected with the voltage sampling circuit, the first current sampling circuit and the second current sampling circuit and is used for determining whether a system is in a hiccup mode or not according to the output voltage of the voltage sampling circuit and a preset rule, if so, the output current of the second current sampling circuit is output to a feedback control device to enable the feedback control device to perform feedback control, and otherwise, the output current of the first current sampling circuit is output to the feedback control device to enable the feedback control device to perform feedback control;
the feedback control device.
3. The resonant circuit for improving current stability according to claim 2, wherein the predetermined rule is: determining that the system is in a non-hiccup mode when the output voltage of the voltage sampling circuit is above a first threshold, determining that the system is in a hiccup mode when the output voltage of the voltage sampling circuit is below a second threshold, and determining that the system is in a mode that was last determined before when the output voltage of the voltage sampling circuit is between the first threshold and the second threshold, wherein the second threshold is less than the first threshold.
4. The resonant circuit for improving current stability of claim 1, further comprising:
and the first end of the ripple current processing circuit is connected with the first end of the load, and the second end of the ripple current processing circuit is connected with the second end of the load.
5. The improved current stability resonant circuit of claim 4, wherein the ripple current processing circuit comprises:
the first resistor is connected with the first end of the load at the first end, and connected with the first end of the first capacitor at the second end;
the second end of the first capacitor is connected with the second end of the load.
6. The resonant circuit for improving current stability according to claim 1, wherein the rectangular wave generating circuit is a full-bridge rectangular wave generating circuit.
7. The resonant circuit for improving current stability according to claim 6, wherein the rectifying circuit is a bridge type fully controlled rectifying circuit, and the resonant tank circuit is an LLC resonant tank.
8. The resonant circuit for improving current stability according to any one of claims 1 to 7, wherein the rectangular wave generating circuit comprises a first rectangular wave generating circuit and a second rectangular wave generating circuit, the resonant tank circuit comprises a first resonant tank circuit and a second resonant tank circuit, and the transforming circuit comprises a first transforming circuit and a second transforming circuit; the rectifying circuit comprises a first rectifying circuit and a second rectifying circuit;
a first output end of the first rectangular wave generating circuit is connected with a first input end of the first resonant tank circuit, and a second output end of the first rectangular wave generating circuit is connected with a second input end of the first resonant tank circuit;
a first output end of the second rectangular wave generating circuit is connected with a first input end of the second resonant tank circuit, and a second output end of the second rectangular wave generating circuit is connected with a second input end of the second resonant tank circuit;
a first output end of the first resonant tank circuit is connected with a first input end of the first voltage transformation circuit, and a second output end of the first resonant tank circuit is connected with a second input end of the first voltage transformation circuit;
the first output end of the second resonance tank circuit is connected with the first input end of the second voltage transformation circuit, and the second output end of the second resonance tank circuit is connected with the second input end of the second voltage transformation circuit;
the first output end of the first voltage transformation circuit is connected with the first input end of the first rectifying circuit, and the second output end of the first voltage transformation circuit is connected with the second input end of the first rectifying circuit;
the first output end of the second voltage transformation circuit is connected with the first input end of the second rectifying circuit, and the second output end of the second voltage transformation circuit is connected with the second input end of the second rectifying circuit;
the positive electrode of the power supply in the second rectangular wave generating circuit is connected with the negative electrode of the power supply in the first rectangular wave generating circuit;
the first output end of the second rectifying circuit is connected with the first output end of the first rectifying circuit, and the common end of the second rectifying circuit is used as the first output end of the rectifying circuit; and the second output end of the second rectifying circuit is connected with the second output end of the first rectifying circuit, and the common end of the second rectifying circuit is used as the second output end of the rectifying circuit.
9. The improved current stability resonant circuit of claim 8 wherein said filter capacitor is an electrolytic capacitor.
10. An electric vehicle charger, characterized in that, comprising a resonance circuit for improving current stability according to any one of claims 1 to 9.
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| CN201810994906.8A CN109302069B (en) | 2018-08-29 | 2018-08-29 | Electric automobile charger and resonant circuit for improving current stability thereof |
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