Resonance circuit, direct-current converter and electric automobile

Abstract

The utility model provides a resonance circuit, a direct-current converter and an electric automobile, the resonance circuit comprises an H-bridge switching circuit, an inductor, a peak current detection circuit, a transformer, a full-wave rectification circuit, a PWM controller and a battery, the positive electrode of the battery is connected with the middle output end of the secondary side of the transformer, and the negative electrode of the battery is grounded; the upper side output end of the primary side of the transformer is connected with one input end of the full-wave rectification circuit, the other input end of the full-wave rectification circuit is connected with the lower side output end of the secondary side of the transformer, and the output end of the PWM controller is connected with a control port of the full-wave rectification circuit; the upper output end of the primary side of the transformer is connected with one end of the inductor, the other end of the inductor is connected with one end of the H-bridge switching circuit, the other end of the H-bridge switching circuit is connected with the lower output end of the primary side of the transformer, and the peak current detection circuit is coupled with the other output end of the primary side of the transformer. The output end of the peak current detection circuit is connected with the input end of the PWM controller.

Description

Technical Field

[0001] The present application relates to the technical field of electric vehicle charging, and in particular to a resonant circuit, a DC converter and an electric vehicle. Background Art

[0002] With the energy consumption and environmental pollution problems brought about by the widespread use of automobiles, electric vehicles have received more and more attention. In existing electric vehicles, DC / DC (direct current to direct current) converters are commonly used components of electric vehicles. With the rapid development of electric vehicles, the requirements for the cost of the entire vehicle are becoming more and more stringent, requiring DC / DC to have bidirectional power conversion power, so as to achieve the goal of converting the high-voltage battery voltage into low voltage to power the low-voltage battery and low-voltage equipment of the entire vehicle, and at the same time, it can also convert the low-voltage battery voltage into high voltage to pre-charge the high-voltage circuit capacitor of the entire vehicle, thereby eliminating the pre-charging device of the entire vehicle to achieve the purpose of reducing the cost and weight of the entire vehicle.

[0003] LLC (resonant circuit) has become a commonly used circuit for DC / DC converters due to its high efficiency and low noise. When the existing reverse power changes, the LLC switch tube is in a hard switching state during operation, which causes the voltage spike value to be very high, which is easy to damage the switch tube and thus affect the stability of the DC / DC. Utility Model Content

[0004] The embodiments of the present application provide a resonant circuit, a DC converter and an electric vehicle, which detect the primary side current of the resonant circuit through a peak current detection circuit, and control the secondary side current according to the detection result, thereby solving the problem of very high voltage spike value of the switch tube when working.

[0005] A first aspect of an embodiment of the present application provides a resonant circuit, the resonant circuit comprising:

[0006] An H-bridge switch circuit, an inductor, a peak current detection circuit, a transformer, a full-wave rectifier circuit, a PWM controller and a battery, wherein the positive electrode of the battery is connected to the middle output terminal of the secondary side of the transformer, the negative electrode of the battery is grounded, the upper output terminal of the primary side of the transformer is connected to an input terminal of the full-wave rectifier circuit, the other input terminal of the full-wave rectifier circuit is connected to the lower output terminal of the secondary side of the transformer, and the output terminal of the PWM controller is connected to the control port of the full-wave rectifier circuit; the upper output terminal of the primary side of the transformer is connected to one end of the inductor, the other end of the inductor is connected to one end of the H-bridge switch circuit, the other end of the H-bridge switch circuit is connected to the lower output terminal of the primary side of the transformer, the peak current detection circuit is coupled and connected to the other output terminal of the primary side of the transformer, and the output terminal of the peak current detection circuit is connected to the input terminal of the PWM control;

[0007] The peak current detection circuit is used to detect the current value on the primary side of the transformer (106) through a coupling connection when the resonant circuit works in reverse, and to send a control signal to the PWM controller (104) to turn off the switch tube in the H-bridge switch circuit (101) when the current value is greater than a current threshold.

[0008] Optionally, the peak current detection circuit includes: a coupler, a bridge rectifier circuit, a resistor and a comparator, wherein two ends of one side of the coupler are respectively connected to the output end of the other end of the primary side of the transformer and the other end of the H-bridge switching circuit, and two ends of the other side of the coupler are respectively connected to two input ends of the bridge rectifier circuit, one output end of the bridge rectifier circuit is connected to the positive input end of the comparator, the other output end of the bridge rectifier circuit is grounded, and the negative input end of the comparator is connected to the comparison voltage; the output end of the comparator is the output end of the peak current detection circuit; and the two ends of the resistor are respectively connected to the two output ends of the bridge rectifier circuit.

[0009] For example, the H-bridge switch circuit includes: 4 MOS tubes and two capacitors, wherein one end of the first capacitor is connected to the source of the first MOS tube and the source of the third MOS tube, and the other end is grounded, the drain of the first MOS tube is connected to the source of the second MOS tube, the third MOS tube is connected to the source of the fourth MOS tube, the drain of the second MOS tube and the drain of the fourth MOS tube are grounded, one end of the second capacitor is connected to the drain of the first MOS tube, and the other end of the second capacitor is connected to the other end of the inductor; the source of the fourth MOS tube is connected to the other end of the H-bridge switch circuit.

[0010] For example, the full-wave rectifier circuit includes: two MOS tubes, wherein the source of the fifth MOS tube is connected to the lower output end of the transformer, the gate of the fifth MOS tube is connected to the output end of the PWM controller, the drain of the fifth MOS tube is grounded, the source of the sixth MOS tube is connected to the upper output end of the transformer, the gate of the sixth MOS tube is connected to the output end of the PWM controller, and the drain of the sixth MOS tube is grounded.

[0011] As an example, the resonant circuit further includes:

[0012] A MOS driver, one end of which is connected to the output end of the PWM controller, and the other end of which is connected to the gate of the fifth MOS tube and the gate of the sixth MOS tube;

[0013] The MOS driver is used to convert the PWM signal into a MOS driving signal.

[0014] As an example, the peak current detection circuit includes: a coupler, a bridge rectifier circuit, a Hall device and a comparator, wherein two ends of one side of the coupler are respectively connected to the output end of the other end of the primary side of the transformer and the other end of the H-bridge switching circuit, and two ends of the other side of the coupler are respectively connected to the two input ends of the bridge rectifier circuit, one output end of the bridge rectifier circuit is connected to the positive input end of the comparator, the other output end of the bridge rectifier circuit is grounded, and the negative input end of the comparator is connected to the comparison voltage; the output end of the comparator is the output end of the peak current detection circuit; and the two ends of the Hall device are respectively connected to the two output ends of the bridge rectifier circuit.

[0015] Optionally, the full-wave rectifier circuit further includes: two protection resistors;

[0016] One end of the first protection resistor is connected to the drain of the fifth MOS tube, and the other end of the first protection resistor is grounded;

[0017] One end of the second protection resistor is connected to the drain of the sixth MOS tube, and the other end of the second protection resistor is grounded.

[0018] Optionally, the resonant circuit further includes: a third capacitor,

[0019] The third capacitor is connected in parallel with the battery.

[0020] In a second aspect, a DC converter is provided, wherein the DC converter comprises the resonant circuit provided in the first aspect.

[0021] In a third aspect, an electric vehicle is provided, comprising the DC converter provided in the second aspect.

[0022] It can be seen that the technical solution adopted by the present application, when the resonant circuit works in reverse, detects the current at the other end of the primary side of the transformer in a coupled manner by setting a peak current detection circuit. When the current is greater than the current threshold, the PWM controller sends a PWM signal to disconnect the switch tube of the full-wave rectifier circuit. In this way, when the primary side current is large, the switch tube can be turned off. Since the peak voltage is proportional to the primary side current, the larger the primary side current, the larger the peak voltage. In this way, when the primary side current is detected to be higher than the current threshold, the switch tube in the full-wave rectifier circuit is directly disconnected through the control loop. In this way, the influence of the peak voltage on the switch tube is avoided, the service life of the switch tube is increased, and the stability of DC / DC is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0024] Figure 1 is a structural block diagram of a resonant circuit provided in an embodiment of the present application;

[0025] Figure 2 is a structural block diagram of a peak current detection circuit provided in an embodiment of the present application;

[0026] Figure 3 is a structural schematic diagram of an H-bridge switch circuit provided in an embodiment of the present application;

[0027] Figure 4 It is a structural schematic diagram of a full-wave rectifier circuit provided in an embodiment of the present application;

[0028] Figure 5 It is a structural schematic diagram of a resonant circuit provided in an embodiment of the present application. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0030] The terms "first", "second", etc. in the specification and claims of this application and the above-mentioned drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but optionally includes steps or units that are not listed, or optionally includes other steps or units inherent to these processes, products or devices.

[0031] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0032] The resonant circuit works forward: When working forward, the resonant circuit is powered by an external power supply to the battery, that is, the external power supply charges the battery. When working forward, the external power supply side of the resonant circuit is the primary side, and the battery side is the secondary side.

[0033] The resonant circuit works in reverse: When working in reverse, the resonant circuit discharges the external power supply from the battery, that is, the battery discharges the external power supply. When working in reverse, the external power supply side of the resonant circuit is the secondary side, and the battery side is the primary side.

[0034] In order to better illustrate the embodiments of this application. Figure 1 , Figure 1 This is a block diagram of the principle of the resonant circuit provided in this application. Figure 1 As shown, the embodiments of the present application are introduced below in conjunction with the accompanying drawings. In the accompanying drawings, dots at the intersection of intersecting wires indicate that the wires are connected, and no dots at the intersection indicate that the wires are not connected.

[0035] The resonant circuit comprises: an H-bridge switch circuit 101, an inductor L1, a peak current detection circuit 102, a transformer 106, a full-wave rectifier circuit 103, a PWM controller 104 and a battery 105, wherein the positive electrode of the battery 105 is connected to the middle output terminal of the secondary side of the transformer 106, and the negative electrode is grounded, the upper output terminal of the secondary side of the transformer 106 is connected to an input terminal of the full-wave rectifier circuit 103, the other input terminal of the full-wave rectifier circuit 103 is connected to the lower output terminal of the secondary side of the transformer 106, and the output terminal of the PWM controller 104 is connected to the control port of the full-wave rectifier circuit 103; the upper output terminal of the primary side of the transformer 106 is connected to one end of the inductor L1, the other end of the inductor L1 is connected to one end of the H-bridge switch circuit 101, the other end of the H-bridge switch circuit 101 is connected to the lower output terminal of the primary side of the transformer 106, the peak current detection circuit 102 is coupled to the other output terminal of the primary side of the transformer 106, and the output terminal of the peak current detection circuit 102 is connected to the input terminal of the PWM controller 104;

[0036] The peak current detection circuit 102 is used to detect the current value of the primary side of the transformer 106 through a coupling connection when the resonant circuit works in reverse, and send a control signal to the PWM controller 104 to turn off the switch tube in the H-bridge switch circuit 101 when the current value is greater than the current threshold;

[0037] The PWM controller 104 is used to generate a PWM signal according to the control signal, and input the PWM signal to the full-wave rectifier circuit 103 through the output terminal. The PWM signal is used to control the disconnection of the switch tube in the full-wave rectifier circuit 103.

[0038] For example, the resonant circuit further includes: a third capacitor C3, which is connected in parallel with the battery 105. The third capacitor C3 connected in parallel with the battery 105 can filter the harmonics of the battery 105.

[0039] The technical solution adopted in the present application is that when the resonant circuit works in reverse, the battery discharges to the outside at this time, and a peak current detection circuit is set to detect the current at the other end of the primary side of the reverse working transformer in a coupled manner. When the current is greater than the current threshold, a PWM signal is sent through the PWM controller to disconnect the switch tube of the full-wave rectifier circuit. In this way, when the primary side current is large, the switch tube can be turned off. Since the peak voltage of the reverse operation is proportional to the primary side current, the larger the primary side current of the reverse operation, the larger the peak voltage. In this way, when the primary side current of the reverse operation is detected to be higher than the current threshold, the switch tube in the full-wave rectifier circuit 103 is directly disconnected through the control loop, thereby avoiding the influence of the peak voltage on the switch tube, increasing the service life of the switch tube, and improving the stability of DC / DC.

[0040] For example, see Figure 2 , Figure 2 The structure diagram of the peak current detection circuit 102 provided in this application is as follows: Figure 2 As shown, the peak current detection circuit includes: a coupler 201, a bridge rectifier circuit, a resistor R1, and a comparator 202, wherein two ends of one side of the coupler 201 are respectively connected to the output end of the other end of the primary side of the transformer 106 and the other end of the H-bridge switch circuit 103, and two ends of the other side of the coupler 201 are respectively connected to two input ends of the bridge rectifier circuit, one output end of the bridge rectifier circuit is connected to the positive input end of the comparator, the other output end of the bridge rectifier circuit is grounded, and the negative input end of the comparator is connected to a comparison voltage Vref (a voltage value corresponding to the current threshold); the output end of the comparator is the output end of the peak current detection circuit 102; and the two ends of the resistor R1 are respectively connected to the two output ends of the bridge rectifier circuit.

[0041] For example, the resistor R1 may be replaced by a Hall device, and the Hall device may specifically include: a Hall sensor.

[0042] When the resonant circuit works in reverse, the battery discharges to the outside. The peak current detection circuit detects the current at the output end of the other end of the primary side of the transformer 106 by setting a coupler, and then outputs the detection signal to the comparator. The comparator compares it with the comparison voltage. When the voltage at the positive input end (that is, the voltage loaded by R1) is greater than the comparison voltage, a high level is output from the output end. The high level is input to the PWM controller, and the PWM controller outputs a PWM signal to control the switch tube to turn off.

[0043] For example, see Figure 3 , Figure 3 The schematic diagram of the structure of the H-bridge switch circuit 101 provided in this application is as follows: Figure 3 As shown, the H-bridge switch circuit includes: 4 MOS tubes and two capacitors, wherein one end of the first capacitor C1 is connected to the source of the first MOS tube Q1 and the source of the third MOS tube Q3, and the other end is grounded, the drain of the first MOS tube Q1 is connected to the source of the second MOS tube Q2, the third MOS tube Q3 is connected to the source of the fourth MOS tube Q4, the drain of the second MOS tube Q2 and the drain of the fourth MOS tube Q4 are grounded, one end of the second capacitor C2 is connected to the drain of the first MOS tube Q1, and the other end of the second capacitor C2 is connected to the other end of the inductor L1; the source of the fourth MOS tube Q4 is connected to the other end of the H-bridge switch circuit 101.

[0044] For example, see Figure 4 , Figure 4 The full-wave rectifier circuit 103 provided in this application is shown in FIG. Figure 4 As shown, the full-wave rectifier circuit 103 includes: two MOS transistors, wherein the source of the fifth MOS transistor Q5 is connected to the lower output end of the primary side of the transformer 106, the gate of the fifth MOS transistor Q5 is connected to the output end of the PWM controller 104, the drain of the fifth MOS transistor Q5 is grounded, the source of the sixth MOS transistor Q6 is connected to the upper output end of the primary side of the transformer 106, the gate of the sixth MOS transistor Q6 is connected to the output end of the PWM controller 104, and the drain of the sixth MOS transistor Q6 is grounded.

[0045] For example, the full-wave rectifier circuit 103 may further include: two protection resistors, wherein:

[0046] One end of the first protection resistor R5 is connected to the drain of the fifth MOS transistor Q5, and the other end of the first protection resistor R5 is grounded;

[0047] One end of the second protection resistor R6 is connected to the drain of the sixth MOS transistor Q6 , and the other end of the second protection resistor R6 is grounded.

[0048] The above technical solution sets a protection resistor for the MOS tube, which can provide overcurrent protection for the MOS tube and increase the life of the MOS tube.

[0049] When the above-mentioned resonant circuit works in reverse, because there is leakage inductance LK1 / LK2 in the transformer winding loop connected in series with the MOS tube Q5 / Q6, the energy stored in the leakage inductance LK1 / LK2 is released at the moment when the MOS tube Q5 / Q6 is turned off, resulting in a spike voltage generated in the MOS tube Q5 / Q6. When the parameters of the resonant circuit are fixed, the peak voltage of the above-mentioned resonant circuit is related to the current I1 / I2 flowing through the leakage inductance LK1 / LK2. The larger the peak voltage, the larger I1 / I2; therefore, the peak voltage can be controlled by controlling the current I1 / I2. In this application, the PWM controller is used to control the shutdown of Q5 and Q6 to disconnect the current I1 / I2, and the peak voltage of Q5 / Q6 is controlled by disconnecting the current I1 / I2, thereby reducing the peak voltage of Q5 / Q6 and improving the stability and service life of the switch tube.

[0050] See also Figure 5 , Figure 5 is a schematic diagram of the current structure of the resonant circuit, such as Figure 5 As shown, the above-mentioned resonant circuit can also include: a MOS driver, one end of which is connected to the output end of the PWM controller 104, and the other end is connected to the gate of the fifth MOS transistor Q5 and the gate of the sixth MOS transistor Q6, and the MOS driver is used to convert the PWM signal into a MOS drive signal.

[0051] The present application also provides a DC converter, which includes the above-mentioned resonant circuit. The specific structure of the DC converter can be found in FIG. Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 shown.

[0052] In another embodiment of the present application, an electric vehicle is provided, comprising the DC converter described in the above embodiment.

[0053] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0054] In the several embodiments provided in the present application, it should be understood that the disclosed resonant circuit can be implemented in other ways. For example, the resonant circuit embodiments described above are only schematic, and for example, the components in the above circuits can also use other components with the same functions. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, circuits or components, which can be electrical or other forms.

[0055] In addition, each circuit in each embodiment of the present application may be integrated into one circuit board, or each circuit may exist as a separate entity, or two or more circuits may be integrated into one circuit board.

[0056] The embodiments of the present application are introduced in detail above. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the present application and its core ideas. At the same time, for those skilled in the art, according to the ideas of the present application, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A resonant circuit, characterized in that: The resonant circuit comprises: an H-bridge switch circuit (101), an inductor, a peak current detection circuit (102), a transformer (106), a full-wave rectification circuit (103), a PWM controller (104) and a battery (105), wherein: The positive electrode of the battery (105) is connected to the middle output terminal of the secondary side of the transformer (106), the negative electrode of the battery (105) is grounded, the upper output terminal of the secondary side of the transformer (106) is connected to an input terminal of the full-wave rectifier circuit (103), the other input terminal of the full-wave rectifier circuit (103) is connected to the lower output terminal of the secondary side of the transformer (106), and the output terminal of the PWM controller (104) is connected to the control port of the full-wave rectifier circuit (103); the upper output terminal of the primary side of the transformer (106) is connected to one end of the inductor, the other end of the inductor is connected to one end of the H-bridge switch circuit (101), the other end of the H-bridge switch circuit (101) is connected to the lower output terminal of the primary side of the transformer (106), the peak current detection circuit (102) is coupled to the other output terminal of the primary side of the transformer (106), and the output terminal of the peak current detection circuit (102) is connected to the input terminal of the PWM controller (104); The peak current detection circuit (102) is used to detect the current value on the primary side of the transformer (106) through a coupling connection when the resonant circuit works in reverse, and to send a control signal to the PWM controller (104) to turn off the switch tube in the H-bridge switch circuit (101) when the current value is greater than a current threshold.

2. The resonant circuit according to claim 1, characterized in that: The peak current detection circuit comprises: a coupler (201), a bridge rectifier circuit, a resistor and a comparator (202), wherein two ends of one side of the coupler are respectively connected to the output end of the other end of the primary side of the transformer (106) and the other end of the H-bridge switch circuit (101), and two ends of the other side of the coupler are respectively connected to two input ends of the bridge rectifier circuit, one output end of the bridge rectifier circuit is connected to the positive input end of the comparator, the other output end of the bridge rectifier circuit is grounded, and the negative input end of the comparator is connected to a comparison voltage; the output end of the comparator is the output end of the peak current detection circuit (102); and the two ends of the resistor are respectively connected to the two output ends of the bridge rectifier circuit.

3. The resonant circuit according to claim 1, characterized in that: The H-bridge switch circuit (101) comprises: four MOS tubes and two capacitors, wherein one end of the first capacitor is connected to the source of the first MOS tube and the source of the third MOS tube, and the other end is grounded; the drain of the first MOS tube is connected to the source of the second MOS tube, the third MOS tube is connected to the source of the fourth MOS tube, the drain of the second MOS tube and the drain of the fourth MOS tube are grounded; one end of the second capacitor is connected to the drain of the first MOS tube, and the other end of the second capacitor is connected to the other end of the inductor; the source of the fourth MOS tube is connected to the other end of the H-bridge switch circuit.

4. The resonant circuit according to claim 1, characterized in that: The full-wave rectification circuit (103) comprises: two MOS transistors, wherein the source of the fifth MOS transistor is connected to the lower output end of the primary side of the transformer (106), the gate of the fifth MOS transistor is connected to the output end of the PWM controller (104), the drain of the fifth MOS transistor is grounded, the source of the sixth MOS transistor is connected to the upper output end of the primary side of the transformer (106), the gate of the sixth MOS transistor is connected to the output end of the PWM controller (104), and the drain of the sixth MOS transistor is grounded.

5. The resonant circuit according to claim 4, characterized in that: The resonant circuit further comprises: A MOS driver, one end of which is connected to the output end of the PWM controller (104), and the other end of which is connected to the gate of the fifth MOS tube and the gate of the sixth MOS tube.

6. The resonant circuit according to claim 1, characterized in that: The peak current detection circuit comprises: a coupler (201), a bridge rectifier circuit, a Hall device and a comparator (202), wherein two ends of one side of the coupler are respectively connected to the output end of the other end of the primary side of the transformer (106) and the other end of the H-bridge switch circuit (101), and two ends of the other side of the coupler are respectively connected to two input ends of the bridge rectifier circuit, one output end of the bridge rectifier circuit is connected to the positive input end of the comparator, the other output end of the bridge rectifier circuit is grounded, and the negative input end of the comparator is connected to a comparison voltage; the output end of the comparator is the output end of the peak current detection circuit (102); and the two ends of the Hall device are respectively connected to the two output ends of the bridge rectifier circuit.

7. The resonant circuit according to claim 4, characterized in that: The full-wave rectification circuit (103) further includes: two protection resistors; One end of the first protection resistor is connected to the drain of the fifth MOS tube, and the other end of the first protection resistor is grounded; One end of the second protection resistor is connected to the drain of the sixth MOS tube, and the other end of the second protection resistor is grounded.

8. The resonant circuit according to claim 1, characterized in that: The resonant circuit further includes: a third capacitor, The third capacitor is connected in parallel with the battery (105).

9. A DC converter, characterized in that: The DC converter comprises a resonant circuit as described in any one of claims 1-8.

10. An electric vehicle, characterized in that: Comprising the DC converter as claimed in claim 9.

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