Charging circuit and charging method of vehicle-mounted power supply and vehicle

Abstract

The invention relates to the technical field of battery charging and discharging, and discloses a charging circuit and a charging method of a vehicle-mounted power supply and a vehicle. The charging circuit comprises a single-stage PFC circuit, a conversion circuit and a clamp voltage circuit, and the single-stage PFC circuit is used for receiving alternating current of an external network, performing half-wave rectification processing on the alternating current and then outputting sine waves; the conversion circuit comprises a first H-type bridge circuit, a second H-type bridge circuit and a resonance circuit, and is used for performing voltage boosting or voltage reduction adjustment on sine waves output by the single-stage PFC circuit and transmitting the adjusted voltage to the clamp voltage circuit; the clamp voltage circuit comprises a capacitor C and a battery management system, and the battery management system comprises a battery pack; and the clamping circuit is used for filtering the adjusted voltage and carrying out clamping control on the output voltage of the battery pack. According to the design of the charging circuit, a single-stage PFC structure is adopted, an inductor L1 and a capacitor C1 are not included, the space occupied by the L1 and the C1 is avoided, and the cost is saved.

Description

Technical Field

[0001] The present invention relates to the technical field of battery charging and discharging, and in particular to a charging circuit, a charging method and a vehicle of a vehicle-mounted power supply. Background Art

[0002] The on-board charger (OBC) is an important component of electric vehicles. It is responsible for transmitting the grid voltage through the ground AC charging pile and AC charging port to the on-board charger, and then charging the electric vehicle battery. OBC refers to a charger fixedly installed on an electric vehicle, which has the ability to safely and automatically charge the electric vehicle power battery. Figure 1 As shown, after the OBC converts AC into DC, it converts it into the DC voltage required by the battery through an isolation transformer (DC-DC) to charge the battery pack. Figure 2 As shown, corresponding to the voltage and current waveforms of the input and output of the OBC, the input voltage and current waveforms are similar to sine waves, the zero phases of the two waveforms are close to overlapping, and the output voltage and current are close to a constant value with small fluctuations.

[0003] At present, the on-board charger circuit, the part of the conversion between AC and DC, generally adopts the totem pole PFC (Power Factor Correction) circuit topology architecture, and the transformer isolation part adopts the LLC resonant converter, or the dual active bridge (Dual Active Bridge) converter topology structure. In this totem pole PFC architecture, inductor L1 and bus capacitor C1 are set, which are large in size, occupying about 1 / 4 of the space of the entire on-board charger, and resulting in low power density. Summary of the invention

[0004] In view of this, the present invention provides a charging circuit, a charging method and a vehicle of an on-board power supply to solve the problem that the inductor L1 and the capacitor C1 in the current OBC charging circuit occupy a large volume.

[0005] In a first aspect, the present invention provides a charging circuit for a vehicle-mounted power supply, the circuit comprising: a single-stage PFC circuit, a conversion circuit and a voltage clamping circuit, wherein:

[0006] The single-stage PFC circuit is an H-bridge circuit composed of four switch tubes, which is used to receive AC power from the external network and output a sine wave after half-wave rectification of the AC power.

[0007] The conversion circuit comprises: a first H-type bridge circuit, a second H-type bridge circuit and a resonant circuit, wherein the resonant circuit is connected between the first H-type bridge circuit and the second H-type bridge circuit, and each H-type bridge circuit is composed of four switch tubes; the first H-type bridge circuit is connected to the single-stage PFC circuit, and the second H-type bridge circuit is connected to the clamping circuit; the conversion circuit is used to perform voltage step-up or step-down adjustment on the sine wave output by the single-stage PFC circuit, and transmit the adjusted voltage to the clamping circuit;

[0008] The voltage clamping circuit includes: a capacitor C and a battery management system, the capacitor C is respectively connected to the output end of the second H-bridge circuit and the battery management system, and the battery management system includes a battery pack; the voltage clamping circuit is used to filter the adjusted voltage and clamp the output voltage of the battery pack.

[0009] The charging circuit of the vehicle power supply provided in this aspect adopts a single-stage PFC structure in the design, does not include inductor L1 and capacitor C1, and uses a conversion circuit and a clamping circuit to realize the functions of L1 and C1 in the original totem pole PFC circuit. The charging circuit of this solution avoids the space occupied by L1 and C1, saving cost.

[0010] In combination with the first aspect, in a possible implementation manner, the four switch tubes in the single-stage PFC circuit are: a first switch tube Q1, a second switch tube Q2, a third switch tube Q3 and a fourth switch tube Q4; wherein the first switch tube Q1 and the third switch tube Q3 are low-frequency switch tubes, and the second switch tube Q2 and the fourth switch tube Q4 are high-frequency switch tubes.

[0011] In combination with the first aspect, in another possible implementation, the first switch tube Q1 , the second switch tube Q2 , the third switch tube Q3 and the fourth switch tube Q4 are all insulated gate bipolar transistors IGBTs or diodes.

[0012] Optionally, when the first switch tube Q1 to the fourth switch tube Q4 are IGBTs, the alternating current is input to the source s of the first switch tube Q1 and the drain d of the fourth switch tube Q4.

[0013] When the first to fourth switch tubes Q1 to Q4 are diodes, the AC power is input to the positive electrode of the first switch tube Q1 and the negative electrode of the fourth switch tube Q4.

[0014] In combination with the first aspect, in another possible implementation manner, after the single-stage PFC circuit performs half-wave rectification on the AC power, the output sine wave is expressed as:

[0015]

[0016] Among them UCD Represents the output sinusoidal voltage, U ac represents the external AC voltage, ω represents the angular frequency, and θ represents the phase.

[0017] In combination with the first aspect, in another possible implementation manner, the conversion circuit performs voltage step-up or step-down adjustment on the sine wave, and the adjusted voltage is expressed as:

[0018] U EF = k·U CD

[0019] Among them, U EF Indicates the voltage adjusted by the conversion circuit, U CD Represents the sinusoidal voltage output by the single-stage PFC circuit, k is U CD Zoom in or out.

[0020] In combination with the first aspect, in another possible implementation, the first H-type bridge circuit is used to control the resonant frequency of the resonant circuit, and adjust the pulse width so that the switch tube in the first H-type bridge circuit is soft-turned on; the resonant circuit is used to store or release energy under the control of the first H-type bridge circuit, and transfer the energy to the secondary side of the transformer; the second H-type bridge circuit is used to rectify and phase-shift the AC voltage on the secondary side of the transformer, so that the switch tube in the second H-type bridge circuit is soft-turned on.

[0021] In a second aspect, the present invention further provides a charging method, which is applied to the charging circuit of the vehicle-mounted power supply as described in the first aspect or any one of the first aspects, and the method comprises:

[0022] The single-stage PFC circuit receives AC power from the external network, performs half-wave rectification on the AC power, and outputs a sine wave;

[0023] The conversion circuit receives the sine wave output by the single-stage PFC circuit, performs voltage step-up or step-down adjustment on the sine wave, and transmits the adjusted voltage to the voltage clamping circuit;

[0024] The voltage clamping circuit filters the adjusted voltage and controls the output voltage clamping of the battery pack in the voltage clamping circuit.

[0025] In combination with the second aspect, in a possible implementation manner, the voltage clamp circuit includes a capacitor C and a battery management system, and the battery management system includes a battery pack; and the method further includes:

[0026] The capacitor C in the voltage clamp circuit filters the adjusted voltage and outputs it to the battery management system;

[0027] The battery management system performs voltage clamping control on the voltage filtered by the capacitor C, and then outputs a constant voltage to the battery pack to charge the battery pack.

[0028] In a third aspect, the present invention further provides a vehicle, comprising a charging circuit for an on-board power supply; the charging circuit for the on-board power supply is the charging circuit described in the first aspect or any one of the first aspects.

[0029] The present invention provides a charging circuit, a charging method and a vehicle for an on-board power supply. A single-stage PFC structure is adopted in the single-stage PFC circuit design, and the inductor L1 and the capacitor C1 are not included. The functions of L1 and C1 in the original totem pole PFC circuit are realized by using a conversion circuit and a clamping circuit. The charging circuit of the present solution avoids the space occupied by L1 and C1, thereby saving cost.

[0030] In addition, two H-type bridge circuits are designed in the conversion circuit, with a resonant circuit structure connected in the middle, to achieve power factor correction and amplification / reduction of the sinusoidal voltage output by the front-end single-stage PFC circuit. Finally, the voltage output by the conversion circuit is filtered and the battery voltage is clamped through the clamping circuit, and a constant current voltage is output to charge the battery pack, realizing the OBC AC to DC conversion function. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 is a framework diagram of an electrical vehicle charger according to an embodiment of the present invention;

[0033] Figure 2 is a schematic diagram of an input voltage and current waveform and an output voltage and current waveform according to an embodiment of the present invention;

[0034] Figure 3a is a schematic diagram of a totem pole PFC and DAB topology according to an embodiment of the present invention;

[0035] Figure 3b is a schematic diagram of a totem pole PFC and LLC topology according to an embodiment of the present invention;

[0036] Figure 3c is a waveform diagram of an input voltage and current waveform and an output voltage and current waveform according to an embodiment of the present invention;

[0037] Figure 4 is a structural block diagram of a charging circuit of a vehicle-mounted power supply according to an embodiment of the present invention;

[0038] Figure 5 is a circuit diagram of a charging circuit of a vehicle-mounted power supply according to an embodiment of the present invention;

[0039] Figure 6 is another waveform diagram of input voltage, current waveform and output voltage, current waveform according to an embodiment of the present invention;

[0040] Figure 7 is a circuit diagram of another charging circuit of a vehicle-mounted power supply according to an embodiment of the present invention;

[0041] Figure 8 is a schematic diagram of the input voltage and current principle of a single-stage PFC according to an embodiment of the present invention;

[0042] Fig. 9 is a waveform diagram of an input voltage and an output voltage according to an embodiment of the present invention;

[0043] Fig.10 is a flow chart of a charging method according to an embodiment of the present invention;

[0044] Fig.11 is a schematic structural diagram of a vehicle according to an embodiment of the present invention. DETAILED DESCRIPTION

[0045] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0046] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0047] Furthermore, the terms “first” and “second” are used for descriptive purposes only and should not be understood as indicating or implying relative importance.

[0048] The technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0049] The technical solution of the present invention is applied to the field of battery charging and discharging technology, and specifically, can be applied to an on-board charger OBC. Figure 1 In addition, in a specific OBC circuit structure, as shown Figure 3a and Figure 3b As shown, two OBC circuit structures are provided.

[0050] like Figure 3a As shown in FIG. 1 , a topology structure composed of a totem pole PFC (Power Factor Correction) and a DAB (Dual Active Bridge) circuit is shown; Figure 3b As shown in FIG. 1 , a topology structure consisting of a totem pole PFC and an LLC resonant converter is shown. The LLC resonant converter is a high-performance DC / DC converter.

[0051] The totem pole PFC architecture, which is the totem pole form of the bridgeless full-bridge circuit, is a circuit architecture for power factor correction of AC power. The totem pole PFC architecture adopts the characteristics of the full-bridge circuit. The AC power supply can be directly converted into DC power supply through the totem pole power conversion unit, and controlled through the voltage loop and current loop compensation network. This architecture eliminates the traditional bridge rectifier, thereby reducing the loss of the rectifier bridge and improving efficiency.

[0052] The characteristics of the totem pole PFC architecture include: (1) High efficiency: The totem pole PFC architecture eliminates the loss of the rectifier bridge, so it can significantly improve efficiency under both low voltage input and high voltage input conditions. (2) High power factor: Through a special control strategy, the totem pole PFC architecture can achieve a unity power factor, thereby reducing the loss caused by reactive power and improving the utilization of the power supply. (3) Small size: Due to the use of high-frequency switching technology and bridgeless design, the totem pole PFC architecture is relatively small in size, which is conducive to the miniaturization and lightweight of the power supply system. (4) High reliability: The totem pole PFC architecture uses advanced control technology and protection strategies, which can effectively prevent the occurrence of abnormal conditions such as overcurrent and overvoltage, thereby improving the reliability of the power supply system.

[0053] The totem pole PFC circuits mentioned above all include: a first inductor L1, a first capacitor C1 (also called bus capacitor), two high-frequency switch power tubes Q1 and Q3, and two low-frequency switch power tubes Q2 and Q4. The function of this part of the circuit is to achieve power factor correction, that is, to control the phase of the input AC voltage to be basically consistent with the phase of the input AC current. The output waveform is as follows: Figure 2As shown, the AC current Iin (A) and Vac (V) are converted into DC current Iout (A) and DC voltage V0 (V) after passing through OBC.

[0054] Optionally, the capacity of the first capacitor C1 is 1600uF (microfarad).

[0055] Although Figure 5 The input voltage and current waveforms shown can reduce the pollution of current harmonics to the power grid, but in its circuit structure, the first inductor L1 and the first capacitor C1 of the totem pole PFC circuit are relatively large, occupying about 1 / 4 of the space of the entire on-board charger OBC, resulting in low power density.

[0056] The technical solution provided in this embodiment proposes a single-stage PFC circuit control technical solution in order to reduce costs, reduce the size of the charger, and improve power density. This solution is applied to Figure 4 The charging circuit shown.

[0057] See also Figure 4 , is a structural block diagram of a charging circuit of a vehicle-mounted power supply according to an embodiment of the present invention. The charging circuit includes: a single-stage PFC circuit, a conversion circuit and a voltage clamping circuit. The conversion circuit is arranged between the single-stage PFC circuit and the voltage clamping circuit.

[0058] Furthermore, if Figure 5 As shown in the figure, the single-stage PFC circuit is an H-bridge circuit composed of four switch tubes, which is used to receive AC power from the external network and output a sine wave after half-wave rectification of the AC power. Figure 4 and Figure 5 As shown, the AC input voltage is Vac, the input current is Iin, and the output voltage is V CD .

[0059] The conversion circuit includes: a first H-type bridge circuit, a second H-type bridge circuit and a resonant circuit, the resonant circuit is connected between the first H-type bridge circuit and the second H-type bridge circuit, each H-type bridge circuit is composed of four switching tubes; the first H-type bridge circuit is connected to the single-stage PFC circuit, and the second H-type bridge circuit is connected to the clamping circuit.

[0060] exist Figure 4 In the conversion circuit shown, the first H-type bridge circuit is an H-type bridge circuit 1, the second H-type bridge circuit is an H-type bridge circuit 2, and the resonant circuit may be an LC resonant circuit including a capacitor and / or an inductor.

[0061] like Figure 5As shown, the first H-type bridge circuit is composed of a fifth switch tube Q5, a sixth switch tube Q6, a seventh switch tube Q7, and an eighth switch tube Q8 to form a full-bridge circuit. The resonant circuit is an LC resonant circuit, and the internal structure of the resonant circuit can adopt the structure of a general LC resonant circuit, which is composed of components such as an inductor (L), a capacitor (C), and a possible resistor (R), and this embodiment does not limit this.

[0062] The second H-type bridge circuit is composed of a ninth switch tube Q9, a tenth switch tube Q10, an eleventh switch tube Q11, and a twelfth switch tube Q12 to form a full-bridge circuit.

[0063] The conversion circuit is used to adjust the voltage of the sine wave output by the single-stage PFC circuit by stepping up or stepping down, and transmit the adjusted voltage to the clamping circuit. For example, the output current is Iout and the output voltage is V0.

[0064] The clamping circuit includes: capacitor C (such as Figure 4 The second capacitor C2 is shown and the battery management system, the capacitor C is connected to the output end of the second H-bridge circuit and the battery management system respectively, and the battery management system (BMS) includes a battery pack and a battery manager (BMC). The clamping circuit is used to filter the adjusted voltage and clamp the output voltage of the battery pack. The battery pack contains at least one battery (battery) or battery module.

[0065] Among them, clamping is a measure to limit the potential of a certain point to a specified potential, which is an overvoltage protection technology. In the battery system, battery voltage clamping specifically refers to clamping the output voltage of the battery to a predetermined safety level through a specific circuit or device to prevent the voltage from being too high or too low and causing damage to the system.

[0066] Specifically, when the battery voltage exceeds the predetermined clamping voltage, the clamping diode will conduct and shunt the excess voltage to the ground or other low potential points, thereby limiting the output voltage of the battery to below the clamping voltage. Similarly, if the battery voltage is too low, the clamping circuit can also take corresponding measures for protection.

[0067] In this embodiment, the voltage clamp circuit is used to protect the battery pack from overvoltage, preventing the battery from generating excessive voltage during charging or discharging, thereby protecting the battery and the system from damage. In addition, it also has a voltage stabilization function: stabilizing the output voltage of the battery pack within a predetermined range, improving the stability and reliability of the system.

[0068] In addition, optionally, at least one relay may be included in the voltage clamping circuit, such as Figure 5 The circuit includes a relay 1 and a relay 2, which are respectively connected to two ends of the second capacitor C2, and are used to achieve accurate control and protection of the output voltage V0 and the output current Iout of the conversion circuit.

[0069] The battery management system (BMS) is responsible for monitoring, controlling, protecting and optimizing the battery pack to ensure safe, reliable and efficient operation of the battery. The BMS includes: the battery pack and the battery manager (BMC, which can be regarded as part of the BMS).

[0070] Furthermore, the functions of the battery pack include: integration and energy storage. Specifically, the battery pack is assembled from multiple battery modules to form an integral unit for storing and providing electrical energy. By connecting battery modules in parallel or in series, the battery pack can increase the voltage, capacity or power of the battery system.

[0071] The protection and support functions include: the battery pack is usually equipped with a shell or protective structure to protect the battery module and BMS from external impact and damage. The battery pack also includes a heat dissipation system to control the battery temperature, prevent overheating, and ensure that the battery operates within a suitable operating temperature range.

[0072] The connection and communication functions include: the battery pack provides an electrical interface for connecting to an external system, such as the drive motor of an electric vehicle or the inverter of an energy storage system. The BMS transmits information and exchanges data with external devices through the communication interface in the battery pack.

[0073] The functions of the battery management system (BMC) include: battery status monitoring, charge and discharge control, balance management, etc. Specifically, the battery status monitoring function includes: real-time monitoring of battery pack parameters such as temperature, voltage, current, capacity, etc. Diagnose the health status of the battery pack and warn of possible faults or safety hazards.

[0074] The charge and discharge control function includes: controlling the working state of the charger and the discharger to ensure that the battery pack is charged and discharged under safe and efficient conditions. Implementing battery protection and balance control to prevent overcharging and overdischarging and extend the battery life. The balance management function includes: monitoring the voltage difference between each cell of the battery pack, controlling the power balance between each cell in the battery pack, and ensuring the stability and efficiency of the overall performance of the battery pack through the balance strategy.

[0075] Specifically, in a possible implementation, the four switches in the above-mentioned single-stage PFC circuit are: a first switch Q1, a second switch Q2, a third switch Q3 and a fourth switch Q4. The first switch Q1 and the third switch Q3 are low-frequency switches, and the second switch Q2 and the fourth switch Q4 are high-frequency switches.

[0076] Furthermore, the second switch tube Q2 and the fourth switch tube Q4 function as power frequency rectifier tubes for rectifying the 50 Hz power frequency input voltage.

[0077] The first switch tube Q1 and the third switch tube Q3 are high-frequency switch tubes, for example, the switching frequency is about tens of Hz, such as 30Hz to 60kHz. In the original totem pole PFC circuit, the first inductor L1 and the first capacitor C1 are included. The high-frequency switch tubes Q1 to Q4 and the first inductor L1 form a boost circuit, which can boost the voltage of a half cycle of the AC input; Figure 3c As shown, the input voltage U is increased by the fast tubes Q1 and Q3 and the boost AB The voltage is then raised and filtered by the first capacitor C1 to output a nearly stable voltage.

[0078] Further, in a possible implementation manner, the first switch tube Q1, the second switch tube Q2, the third switch tube Q3 and the fourth switch tube Q4 are of insulated gate bipolar transistors (IGBT) or diodes, such as Figure 7 shown.

[0079] IGBT is a composite fully controlled voltage driven power semiconductor device. It is composed of BJT (bipolar junction transistor) and MOS (insulated gate field effect transistor), and has the advantages of the above two devices. IGBT contains four main regions, namely the emitter region (P+), collector region (N-), drift region (N+) and gate region (P), which together form a PNPN stacked structure. There are three electrodes on the outside, namely the gate g, collector c and emitter e.

[0080] In an IGBT, when a positive bias is applied to the gate, a conductive N-type channel can be formed between the N-region and the bottom of the P, allowing current to flow from the collector to the emitter. When the gate voltage drops below a certain threshold, the conductive channel disappears, the IGBT is turned off, and current is prevented from flowing. In this embodiment, the IGBT is mainly used in traction inverters and charging systems in electric vehicles, responsible for converting the DC power stored in the battery into AC power for driving the motor.

[0081] In this embodiment, the switch tubes Q5 to Q8 and the switch tubes Q9 to Q12 are all MOS tubes, such as IGBTs.

[0082] Figure 5In the charging circuit shown in the figure, in the full-bridge circuit of the single-stage PFC, when the first switch tube Q1 to the fourth switch tube Q4 are IGBTs, the AC power is input to the source s of the first switch tube Q1 and the drain d of the fourth switch tube Q4; when the first switch tube Q1 to the fourth switch tube Q4 are diodes, the AC power is input to the positive electrode of the first switch tube Q1 and the negative electrode of the fourth switch tube Q4. Among them, in the structure of the switch tubes Q1 to Q4, the drain d of the first switch tube Q1 and the drain d of the second switch tube Q2 are both connected to point C, and the source s of the third switch tube Q3 and the source s of the fourth switch tube Q4 are connected to point D (point D is grounded).

[0083] In addition, the waveforms of the output voltage V0 (V) and output current Iout (A) of the circuit also change. Figure 6 As shown, the input voltage Vac and the input current Iin are input waveforms with similar phases. After passing through the conversion circuit, the output voltage V0 (V) and the output current Iout (A) become sinusoidal waves, and the peak value of the output current Iout is higher than the output voltage V0.

[0084] like Figure 7 As shown, the switch tubes Q1~Q4 are designed as diodes, that is, corresponding to Q1~Q4, Figure 7 The first diode D1, the second diode D2, the third diode D3 and the fourth diode D4 are formed. The AC power is input to both ends of AB, the A end is connected to the positive electrode of the first diode D1, and the B end is connected to the negative electrode of the third diode D3. The positive and negative connection structure of D2 and D4 is shown in FIG. Figure 7 shown.

[0085] The charging circuit of the vehicle power supply provided in this embodiment is designed to adopt a single-stage PFC structure, does not include the first inductor L1 and the first capacitor C1, and uses a conversion circuit and a clamping circuit to implement the functions of L1 and C1 in the totem pole PFC circuit. The charging circuit of this solution avoids the space occupied by L1 and C1, so that the volume of the OBC is reduced by more than 20%, which saves device costs accordingly, that is, saves cost expenses.

[0086] With the above Figure 3a and Figure 3b Compared with the OBC structure shown in FIG. 1 , the embodiment of the present invention provides a single-stage PFC vehicle charging circuit, which changes the fast tubes Q1 and Q3 in the totem pole PFC circuit into slow tubes, designed as 50Hz switching power tubes, and realizes power factor correction through the switching tubes Q1 to Q8. AB There is no PFC inductor (such as L1) between U CDThere is no electrolytic capacitor (such as C1) between them, and the switch tubes Q1~Q4 are ordinary IGBTs or MOS tubes or diodes to realize power frequency rectification. That is, two H-type bridge circuits are designed in the conversion circuit, and a resonant circuit structure is connected in the middle to achieve power factor correction and amplification / reduction of the sine wave voltage output by the front-end single-stage PFC circuit. Finally, the voltage output by the conversion circuit is filtered and the battery voltage is clamped through the clamping circuit, and the constant current voltage is output to charge the battery pack, realizing the function of OBC AC to DC conversion.

[0087] It should be noted that, in another possible implementation of this embodiment, the first capacitor C1 can be replaced by a film capacitor, for example, a film capacitor of tens of microfarads can be used to replace C1, which can also achieve the effect of reducing volume and reducing costs. Similarly, the first inductor L1 can be replaced by a leakage inductor in a common mode inductor, that is, including a leakage inductor and a film capacitor, which can also achieve the effect of reducing volume and saving costs.

[0088] See also Figure 8 , is a schematic diagram of the working principle of the single-stage PFC in the above embodiment, assuming that the input voltage U AB It is a sine wave. When the input voltage U AB In the positive half cycle, the input current Iin enters point C from point A through the first switch tube Q1, and then returns to point B from point D through the fourth switch tube Q4. The positive half cycle is expressed as: A→Q1→C→D→Q4→B.

[0089] The negative half-cycle input current Iin enters point C from point B through the second switch tube Q2, and then returns to point A from point D through the third switch tube Q3. The negative half-cycle is expressed as: B→Q2→C→D→Q3→A.

[0090] U AB The voltage relationship is expressed by the following formula:

[0091]

[0092] Among them, Uac is the peak value of the sinusoidal wave voltage (i.e., the external grid AC voltage), ω represents the angular velocity, and θ represents the initial phase angle.

[0093] Since the single-stage PFC circuit has no input inductor L1 and electrolytic capacitor C1, it has no effect on the input waveform amplitude; therefore, the input voltage is directly converted into a forward voltage without gain change. After the single-stage PFC circuit performs half-wave rectification on the AC power, the absolute value of the negative half cycle of sin is taken to output a sine wave, U CD The voltage waveform is expressed by the following formula:

[0094]

[0095] Among them, U CD represents the output sinusoidal voltage, ω represents the angular velocity, and θ represents the initial phase angle.

[0096] like Figure 8 and Fig. 9 As shown, the single-stage PFC will CD The voltage is transferred to the secondary side second H-type bridge circuit after the resonance between the first H-type bridge circuit (including the switch tubes Q5-Q8) and the resonant circuit. After the rectification by the second H-type bridge circuit (including the switch tubes Q9-Q12), the output voltage U EF The function of this circuit is to boost the primary voltage to the secondary voltage, thereby achieving a close phase between the voltage and current. Fig. 9 As shown. The adjusted voltage U EF It can be expressed by the following formula:

[0097] U EF = k·U CD

[0098]

[0099] Among them, U EF Indicates the voltage adjusted by the conversion circuit, U CD Represents the sinusoidal voltage output by the single-stage PFC circuit, k is U CD In this embodiment, when k>1, k is the magnification factor or amplification factor.

[0100] Among them, the first H-type bridge circuit is used to control the resonant frequency of the resonant circuit LC, so that LC stores and releases energy, and transfers the energy to the inductance of the secondary side of the transformer to achieve the transfer of electric energy. In addition, the first H-type bridge circuit can also adjust the pulse width so that the four switch tubes Q5 to Q8 are turned on at zero current, thereby achieving soft turning on and improving circuit energy efficiency.

[0101] The resonant circuit is used to store and release energy, and transfer the stored energy and electricity to the secondary side of the transformer to achieve grid isolation and voltage regulation.

[0102] The second H-bridge circuit is used to rectify and phase-shift the AC voltage on the secondary side of the transformer. The second H-bridge can be soft-opened through phase-shift control to improve the circuit efficiency.

[0103] Finally, the adjusted voltage U EF The voltage clamp circuit is provided with a second capacitor C2, which can transmit the U EFThe battery pack is used for filtering and clamping the output battery voltage. Therefore, the output voltage Vo is close to the constant voltage output under the premise of ignoring the influence of ripple voltage. At this time, sin(ωt+θ)=1, and the output voltage V O It can be expressed by the following formula:

[0104] With the above Figure 3a or Figure 3b Compared with the totem pole PFC circuit shown in the figure (also known as the traditional OBC technology solution), the input voltage U AB and U CD After totem pole PFC rectification and filtering, it is expressed by the following expression:

[0105]

[0106]

[0107] Among them, k1 represents the voltage amplification factor after the totem pole PFC boost, k2 is U CD After the resonance between the four switch tubes Q5~Q8 and the transformer, it is transmitted to the secondary side Q9~Q12 for rectification to form the output voltage U EF The function of this circuit is to boost the primary voltage to the secondary side, thereby achieving a close phase between the voltage and current. Ignoring the influence of the ripple voltage, the output voltage Vo can be expressed by the following formula:

[0108]

[0109] The traditional OBC technical solution realizes two-stage power factor correction through a total of 8 switch tubes Q1 to Q8, and can realize two-stage voltage adjustment, that is, two amplification factors k1 and k2. The single-stage OBC technology adopted in the embodiment of the present invention simplifies the circuit, that is, it can be realized by using one amplification factor k, and only needs to realize power factor correction through four switch tubes Q5 to Q8, while saving the space occupied by L1 and C1 in the traditional OBC solution, reducing cost.

[0110] This embodiment also provides a charging method, which can be applied to the above Figure 4 , Figure 5 and Figure 7 The charging circuit of the vehicle power supply shown in FIG. Fig.10 As shown, the method includes:

[0111] Step S101: The single-stage PFC circuit receives AC power from the external network, performs half-wave rectification on the AC power, and outputs a sine wave. The voltage of the AC power from the external network is represented by U AB , the sine wave voltage is U CD .

[0112] Step S102: The conversion circuit receives the sine wave U output by the single-stage PFC circuit. CD , for the sine wave U CD Perform voltage step-up or step-down adjustment and convert the adjusted voltage U EF Transmitted to the clamping circuit;

[0113] Step S103: The voltage clamp circuit adjusts the voltage U EF Filtering, and clamping control of the output voltage U0 of the battery pack in the voltage clamping circuit, so that the output voltage U0 charges the battery pack.

[0114] Specifically, the voltage clamp circuit includes a second capacitor C2 and a battery management system BMS, and the battery management system includes a battery pack and a battery manager BMC; the above method step S103 also includes:

[0115] The second capacitor C2 in the voltage clamp circuit adjusts the adjusted voltage U EF The voltage is filtered and output to the battery management system BMS; after the battery management system BMS performs voltage clamping control on the voltage filtered by the second capacitor C2, it outputs a constant voltage U0 to the battery pack to charge the battery pack.

[0116] The further functional description of each of the above methods is the same as that of the above corresponding embodiments and will not be repeated here.

[0117] The method provided in this embodiment utilizes the charging circuit designed in the aforementioned embodiment. The charging circuit saves PFC inductance and electrolytic capacitors, and utilizes single-stage PFC to change the external network AC voltage from a constant value to a sinusoidal waveform, thereby avoiding the space occupied by L1 and C1 and saving cost.

[0118] In addition, the power factor correction function can also be achieved by replacing the original fast switching tubes Q1 and Q3 with slow tubes.

[0119] The embodiment of the present invention further provides a vehicle, such as Fig.11 As shown, the vehicle includes an on-board charger OBC; the on-board charger OBC is equipped with a charging circuit of an on-board power supply, which is used to convert external network AC power into constant current power to charge the battery pack.

[0120] Among them, the charging circuit of the vehicle power supply is the aforementioned Figure 4 , Figure 5 , Figure 7 The circuit structure shown, specifically, the construction and function of each circuit structure refer to the description of the previous embodiment and will not be repeated here.

[0121] The above embodiments are only used to illustrate the technical solutions of the embodiments of the present invention, rather than to limit them. Although the embodiments of the present invention are described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some of the technical features therein by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A charging circuit for a vehicle-mounted power supply, characterized in that: The circuit comprises: a single-stage PFC circuit, a conversion circuit and a voltage clamping circuit, wherein: The single-stage PFC circuit is an H-bridge circuit composed of four switch tubes, which is used to receive AC power from the external network and output a sine wave after half-wave rectification of the AC power. The conversion circuit comprises: a first H-type bridge circuit, a second H-type bridge circuit and a resonant circuit, wherein the resonant circuit is connected between the first H-type bridge circuit and the second H-type bridge circuit, and each H-type bridge circuit is composed of four switch tubes; the first H-type bridge circuit is connected to the single-stage PFC circuit, and the second H-type bridge circuit is connected to the clamping circuit; the conversion circuit is used to perform voltage step-up or step-down adjustment on the sine wave output by the single-stage PFC circuit, and transmit the adjusted voltage to the clamping circuit; The voltage clamping circuit includes: a capacitor C and a battery management system, the capacitor C is respectively connected to the output end of the second H-bridge circuit and the battery management system, and the battery management system includes a battery pack; the voltage clamping circuit is used to filter the adjusted voltage and clamp the output voltage of the battery pack.

2. The charging circuit according to claim 1, characterized in that: The four switch tubes in the single-stage PFC circuit are: a first switch tube Q1, a second switch tube Q2, a third switch tube Q3 and a fourth switch tube Q4; The first switch tube Q1 and the third switch tube Q3 are low-frequency switch tubes, and the second switch tube Q2 and the fourth switch tube Q4 are high-frequency switch tubes.

3. The charging circuit according to claim 2, characterized in that: The first switch tube Q1 , the second switch tube Q2 , the third switch tube Q3 and the fourth switch tube Q4 are all insulated gate bipolar transistors IGBTs or diodes.

4. The charging circuit according to claim 3, characterized in that: When the first switch tube Q1 to the fourth switch tube Q4 are IGBTs, the AC power is input to the source electrode s of the first switch tube Q1 and the drain electrode d of the fourth switch tube Q4; When the first to fourth switch tubes Q1 to Q4 are diodes, the AC power is input to the positive electrode of the first switch tube Q1 and the negative electrode of the fourth switch tube Q4.

5. The charging circuit according to any one of claims 1 to 4, characterized in that: After the single-stage PFC circuit performs half-wave rectification on the AC power, the output sine wave is expressed as: Among them, U CD Represents the output sinusoidal voltage, U ac represents the external AC voltage, ω represents the angular frequency, and θ represents the phase.

6. The charging circuit according to claim 5, characterized in that: The conversion circuit performs voltage step-up or step-down adjustment on the sine wave, and the adjusted voltage is expressed as: IN EF =k·U CD Among them, U EF Indicates the voltage adjusted by the conversion circuit, U CD Represents the sinusoidal voltage output by the single-stage PFC circuit, k is U CD Zoom in or out.

7. The charging circuit according to any one of claims 1 to 4, characterized in that: The first H-type bridge circuit is used to control the resonant frequency of the resonant circuit and adjust the pulse width so that the switch tube in the first H-type bridge circuit is soft-turned on; The resonant circuit is used to store or release energy under the control of the first H-bridge circuit, and transfer the energy to the secondary side of the transformer; The second H-type bridge circuit is used to rectify and phase-shift the AC voltage on the secondary side of the transformer, so that the switch tube in the second H-type bridge circuit is soft-turned on.

8. A charging method, characterized in that: A charging circuit applied to a vehicle-mounted power supply according to any one of claims 1 to 7, the method comprising: The single-stage PFC circuit receives AC power from the external network, performs half-wave rectification on the AC power, and outputs a sine wave; The conversion circuit receives the sine wave output by the single-stage PFC circuit, performs voltage step-up or step-down adjustment on the sine wave, and transmits the adjusted voltage to the voltage clamping circuit; The voltage clamping circuit filters the adjusted voltage and controls the output voltage clamping of the battery pack in the voltage clamping circuit.

9. The charging method according to claim 8, characterized in that: The voltage clamp circuit includes a capacitor C and a battery management system, and the battery management system includes a battery pack; The method further comprises: The capacitor C in the voltage clamp circuit filters the adjusted voltage and outputs it to the battery management system; The battery management system performs voltage clamping control on the voltage filtered by the capacitor C, and then outputs a constant voltage to the battery pack to charge the battery pack.

10. A vehicle, characterized in that: The vehicle includes an on-board charger; The on-board charger is equipped with a charging circuit of the on-board power supply according to any one of claims 1 to 7.

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