Charging circuit, vehicle-mounted charger and vehicle

Abstract

The invention discloses a charging circuit, a vehicle-mounted charger and a vehicle, and relates to the technical field of vehicle-mounted charging. Comprising a power factor correction unit and a resonance unit, the input end of the power factor correction unit is electrically connected with an external power supply, and the output end is electrically connected with the input end of the resonance unit; the output end of the resonance unit is electrically connected with a load; a voltage stabilizing capacitor is not arranged in the power factor correction unit, and the power factor correction unit is configured to rectify and boost a voltage from an external power supply to generate a fluctuating output voltage to the resonance unit; and the resonance unit is configured to regulate the output voltage at a fixed transformation ratio and generate fluctuating voltage to charge a load. An electrolytic capacitor is directly omitted, the size expenditure is obviously reduced, the cost is well saved, miniaturization and cost reduction of the vehicle-mounted charger are facilitated, and driving control is simpler. While the heat dissipation is sufficient, the assembly process is relatively simple, and the production line is convenient to operate.

Description

Technical Field

[0001] The present application relates to the field of vehicle-mounted charging technology, and in particular to a charging circuit, a vehicle-mounted charger, and a vehicle. Background Art

[0002] With the rapid development of new energy vehicles, especially electric vehicles, the power density requirements for power devices are becoming increasingly higher. Generally speaking, for the same output power, the size of the device restricts the improvement of power density. For electric vehicle on-board chargers, since they use an external AC power supply to charge the load (such as a power battery with the function of receiving and storing electrical energy), they must have large power devices such as rectification, inversion, boost, and voltage stabilization.

[0003] In the existing technology, on-board chargers are basically divided into two major structures: PFC (Power Factor Correction) and LLC (Resonant Converter). Among them, the electrolytic capacitors used for voltage stabilization in PFC occupy a relatively large volume, which greatly affects the improvement of power density and indirectly leads to an increase in cost, which is very unfavorable to the miniaturization and cost reduction of on-board chargers.

[0004] Application Contents

[0005] In view of the above problems, the present application provides a charging circuit, an on-board charger and a vehicle, which better solve the above problems.

[0006] In a first aspect, an embodiment of the present application provides a charging circuit, the charging circuit comprising: a power factor correction unit, a resonance unit;

[0007] The input end of the power factor correction unit is electrically connected to the external power supply, and the output end is electrically connected to the input end of the resonance unit;

[0008] The output end of the resonant unit is electrically connected to the load;

[0009] The power factor correction unit is configured to rectify and boost the voltage from the external power supply to generate a fluctuating output voltage to the resonance unit;

[0010] The resonant unit is configured to regulate the output voltage with a fixed transformation ratio to generate a fluctuating voltage for charging the load.

[0011] Optionally, the power factor correction unit includes: a first bridge arm, a second bridge arm, and a third bridge arm;

[0012] The first end of the first bridge arm is electrically connected to the first end of the second bridge arm, the first end of the third bridge arm, and the first end of the resonant unit respectively;

[0013] The second end of the first bridge arm is electrically connected to the second end of the second bridge arm, the second end of the third bridge arm, and the second end of the resonant unit respectively;

[0014] The third end of the first bridge arm is electrically connected to the first phase line of the external power supply;

[0015] The third end of the second bridge arm is electrically connected to the second phase line of the external power supply;

[0016] The third end of the third bridge arm is electrically connected to the neutral line of the external power supply;

[0017] The external power supply is a single-phase power supply, and the first phase line and the second phase line are obtained by dividing one phase line of the external power supply into two phases.

[0018] Optionally, the power factor correction unit further includes: a first inductor and a second inductor;

[0019] A first end of the first inductor is electrically connected to the first phase line, and a second end of the first inductor is electrically connected to the third end of the first bridge arm;

[0020] A first end of the second inductor is electrically connected to the second phase line, and a second end of the second inductor is electrically connected to the third end of the second bridge arm;

[0021] The first inductor, the second inductor, the first bridge arm, and the second bridge arm form a boost structure, and the voltage from the external power supply is boosted by changing the duty cycle of the respective switching tubes in the first bridge arm and the second bridge arm;

[0022] The switching frequency of the switch tube in the third bridge arm is the same as the frequency of the external power supply. By changing the on and off of the switch tube in the third bridge arm, the voltage from the external power supply is rectified.

[0023] Optionally, the power factor correction unit includes: the power factor correction unit includes: a first bridge arm, a second bridge arm, a third bridge arm, and a fourth bridge arm;

[0024] The first end of the first bridge arm is electrically connected to the first end of the second bridge arm, the first end of the third bridge arm, the first end of the fourth bridge arm, and the first end of the resonant unit respectively;

[0025] The second end of the first bridge arm is electrically connected to the second end of the second bridge arm, the second end of the third bridge arm, the second end of the fourth bridge arm, and the second end of the resonant unit respectively;

[0026] The third end of the first bridge arm is electrically connected to the first phase line of the external power supply;

[0027] The third end of the second bridge arm is electrically connected to the second phase line of the external power supply;

[0028] The third end of the third bridge arm is electrically connected to the third phase line of the external power supply;

[0029] The third end of the fourth bridge arm is electrically connected to the neutral line of the external power supply

[0030] The external power supply is a three-phase power supply, which provides the first phase line, the second phase line and the third phase line respectively.

[0031] Optionally, the power factor correction unit further includes: a first inductor, a second inductor, and a third inductor;

[0032] A first end of the first inductor is electrically connected to the first phase line, and a second end of the first inductor is electrically connected to the third end of the first bridge arm;

[0033] A first end of the second inductor is electrically connected to the second phase line, and a second end of the second inductor is electrically connected to the third end of the second bridge arm;

[0034] A first end of the third inductor is electrically connected to the third phase line, and a second end of the third inductor is electrically connected to the third end of the third bridge arm;

[0035] The first inductor, the second inductor, the third inductor, the first bridge arm, the second bridge arm, and the third bridge arm form a boost structure, and the voltage from the external power supply is boosted by changing the duty cycle of the respective switching tubes in the first bridge arm, the second bridge arm, and the third bridge arm;

[0036] The switching frequency of the switch tube in the fourth bridge arm is the same as the frequency of the external power supply. By changing the on and off of the switch tube in the fourth bridge arm, the voltage from the external power supply is rectified.

[0037] Optionally, the resonant unit includes: a fifth bridge arm, a sixth bridge arm, a seventh bridge arm, an eighth bridge arm, a first capacitor, a fourth inductor, and a transformer;

[0038] The first end of the fifth bridge arm and the first end of the sixth bridge arm are both electrically connected to the first end of the power factor correction unit;

[0039] The second end of the fifth bridge arm and the second end of the sixth bridge arm are both electrically connected to the second end of the power factor correction unit;

[0040] The first end of the first capacitor is electrically connected to the third end of the fifth bridge arm, and the second end is electrically connected to the primary side of the transformer;

[0041] The first end of the fourth inductor is electrically connected to the third end of the sixth bridge arm, and the second end is electrically connected to the primary side of the transformer;

[0042] The secondary side of the transformer is electrically connected to the third end of the seventh bridge arm and the third end of the eighth bridge arm respectively;

[0043] The first end of the seventh bridge arm is electrically connected to the first end of the eighth bridge arm and the first end of the load respectively;

[0044] The second end of the seventh bridge arm is electrically connected to the second end of the eighth bridge arm and the second end of the load respectively.

[0045] Optionally, the switching frequency of each switch tube in the fifth bridge arm and the sixth bridge arm is fixed to a preset frequency, and the output voltage is inverted in combination with the first capacitor and the fourth inductor by changing the on and off states of the switch tubes to obtain a fluctuating inverter voltage;

[0046] The transformer is configured to transform the inverter voltage to obtain a voltage-regulated fluctuating inverter voltage;

[0047] The fluctuating inverter voltage is rectified by changing the on and off states of the respective switching tubes in the seventh bridge arm and the eighth bridge arm to obtain the fluctuating voltage.

[0048] Optionally, the resonance unit includes: the resonance unit includes: a fifth bridge arm, a sixth bridge arm, a seventh bridge arm, an eighth bridge arm, a first capacitor, a second capacitor, a fourth inductor, a fifth inductor, and a transformer;

[0049] The first end of the fifth bridge arm and the first end of the sixth bridge arm are both electrically connected to the first end of the power factor correction unit;

[0050] The second end of the fifth bridge arm and the second end of the sixth bridge arm are both electrically connected to the second end of the power factor correction unit;

[0051] The first end of the first capacitor is electrically connected to the third end of the fifth bridge arm, and the second end is electrically connected to the primary side of the transformer;

[0052] The first end of the fourth inductor is electrically connected to the third end of the sixth bridge arm, and the second end is electrically connected to the primary side of the transformer;

[0053] The secondary side of the transformer is electrically connected to the first end of the second capacitor and the first end of the fifth inductor respectively;

[0054] The second end of the fifth inductor is electrically connected to the third end of the seventh bridge arm;

[0055] The second end of the second capacitor is electrically connected to the third end of the eighth bridge arm;

[0056] The first end of the seventh bridge arm is electrically connected to the first end of the eighth bridge arm and the first end of the load respectively;

[0057] The second end of the seventh bridge arm is electrically connected to the second end of the eighth bridge arm and the second end of the load respectively.

[0058] Optionally, when the load is charged, the switching frequency of each switch tube in the fifth bridge arm and the sixth bridge arm is fixed to a preset frequency, and the output voltage is inverted in combination with the first capacitor and the fourth inductor by changing the on and off states of the switch tubes to obtain a fluctuating inverter voltage;

[0059] The transformer is configured to transform the inverter voltage to obtain a voltage-regulated fluctuating inverter voltage;

[0060] The fluctuating voltage is obtained by changing the on and off states of the respective switching tubes in the seventh bridge arm and the eighth bridge arm and rectifying the fluctuating inverter voltage in combination with the second capacitor and the fifth inductor.

[0061] Optionally, when the load is discharging, the stable voltage continuously generated by the load is inverted into a stable inverter voltage after passing through the seventh bridge arm, the eighth bridge arm, the second capacitor, and the fifth inductor;

[0062] The stable inverter voltage is rectified into a stable rectified voltage after passing through the fifth bridge arm and the sixth bridge arm;

[0063] The stable rectified voltage is inverted into an industrial frequency AC voltage after passing through the power factor calibration unit and output.

[0064] Optionally, the charging circuit further includes: a voltage reduction unit;

[0065] The step-down unit is used to step down the fluctuating voltage to supply power to low-voltage equipment; or

[0066] The step-down unit is used to step down the stable voltage generated by the load to supply power to the low-voltage device.

[0067] Optionally, the step-down unit includes: a plurality of inverter bridge arms, a step-down transformer, a plurality of rectifier bridge arms, and a voltage stabilizing capacitor;

[0068] The first ends of the plurality of inverter bridge arms are electrically connected to the first end of the resonance unit, and the second ends thereof are electrically connected to the second end of the resonance unit;

[0069] The third end of each inverter bridge arm is electrically connected to the primary side of the step-down transformer;

[0070] The secondary side of the step-down transformer is electrically connected to the first ends of the plurality of rectifier bridge arms, the first end of the voltage stabilizing capacitor, and the first end of the low-voltage device respectively;

[0071] The second ends of the plurality of rectifier bridge arms are electrically connected to the second end of the voltage stabilizing capacitor and the second end of the low-voltage device;

[0072] Wherein, the multiple inverter bridge arms are used to invert the fluctuating voltage or the stable voltage;

[0073] The step-down transformer is used to step down the fluctuating voltage after inversion or the stable voltage after inversion to obtain a fluctuating step-down voltage or a stable step-down voltage;

[0074] The multiple rectifier bridge arms combine with the voltage stabilizing capacitor to rectify the fluctuating step-down voltage or the stable step-down voltage to obtain a stable rectified voltage to power the low-voltage equipment.

[0075] Optionally, the charging circuit further includes: a filtering unit;

[0076] The filtering unit is arranged between the input end of the power factor correction unit and the output end of the external voltage, and is used to filter and stabilize the voltage output by the external voltage, or to filter and stabilize the voltage transmitted in reverse by the load.

[0077] Optionally, the load includes: a device having the function of receiving and storing electric energy.

[0078] In a second aspect, an embodiment of the present application provides an on-board charger, comprising: a charging circuit as described in any one of the first aspects.

[0079] Optionally, a power module is included, the power module is partially immersed in the water channel, and the power module integrates a target switch tube. The target switch tube includes all the switch tubes in the power factor correction unit and the resonance unit.

[0080] Optionally, the target switch tube also includes all switch tubes in the step-down unit.

[0081] Optionally, the on-board charger includes: a power board;

[0082] The power module also integrates a driver chip, which is controlled by the power board and controls the on and off of each switch tube;

[0083] The power board is connected to the power module. The power board is integrated with a control chip for controlling all switching tubes in the power factor correction unit and the resonance unit to realize the function of the on-board charger.

[0084] Optionally, the power module is directly attached to the water channel and partially immersed in the water channel;

[0085] The power module includes: an overcurrent terminal, a plastic package shell, a heat dissipation base plate, and a signal terminal;

[0086] The switch tube is integrated and packaged in the plastic housing;

[0087] The heat dissipation base plate serves as the bottom of the power module, is installed on the outside of the plastic package shell, and is immersed in the water channel;

[0088] The overcurrent terminal extends out of the plastic housing and is used to connect to low-voltage equipment in the vehicle;

[0089] The signal terminal extends out of the plastic housing and is used to be connected to the power board.

[0090] Optionally, the heat dissipation base plate is provided with comb-shaped teeth, and the comb-shaped teeth are embedded in the water channel and become part of the water channel.

[0091] Optionally, the on-board charger further includes: a filter board, an auxiliary source drive board, and a magnetic device;

[0092] The filter board is integrated with the magnetic device and connected to the power board. The filter board is used to filter and stabilize the voltage output by the external power supply or the voltage output by the load.

[0093] The auxiliary source driving board is connected to the power board and the power module respectively, and is used to provide the required low voltage to the power board and the driving chip;

[0094] The magnetic device includes: an inductor in the power factor correction unit, a transformer in the resonance unit, and a transformer in the step-down unit;

[0095] The power board is also integrated with other parts, including: a sampling structure, a communication structure, the power factor correction unit, the resonance unit, and the remaining structures of the step-down unit except the switch tube, the inductor, and the transformer.

[0096] In a third aspect, an embodiment of the present invention further provides a vehicle, comprising: the on-board charger described in the second aspect above.

[0097] The charging circuit proposed in this application directly eliminates the electrolytic capacitor, utilizes the characteristics of the load itself, breaks the prejudice of the existing technology, and directly uses the fluctuating voltage to charge the load, which significantly reduces the volume cost and saves a lot of cost, which is very beneficial to the miniaturization and cost reduction of the on-board charger. At the same time, because the frequency of the switching tube in the resonant unit is fixed, there is no need to adjust the voltage range by adjusting the frequency, so the drive control (that is, the control logic) is simpler. And all the switching tubes are integrated and packaged into a power module, which is more conducive to the convection heat dissipation of the coolant. While fully dissipating the heat, its assembly process is relatively simple, the production line operation is convenient, and it has high practicality. BRIEF DESCRIPTION OF THE DRAWINGS

[0098] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiment below. The accompanying drawings are for illustration purposes only and are not to be considered as limiting the present application. The same reference symbols are used throughout the drawings to represent the same components. In the drawings:

[0099] Figure 1 The present invention is a partial structure of a vehicle-mounted charger in the prior art;

[0100] Figure 2 The invention relates to a heat dissipation structure of an on-board charger in the prior art;

[0101] Figure 3 is a modular schematic diagram of a charging circuit according to an embodiment of the present application;

[0102] Figure 4 This is a modular schematic diagram of a preferred charging circuit in an embodiment of the present application;

[0103] Figure 5 is a modular schematic diagram of a charging circuit including a step-down unit in an embodiment of the present application;

[0104] Figure 6 This is a schematic diagram of the structure of the first preferred structure of the power factor correction unit in the embodiment of the present application, combined with the first preferred structure of the resonance unit and including a step-down unit;

[0105] Figure 7 This is a schematic diagram of the structure of the first preferred structure of the power factor correction unit in the embodiment of the present application combined with the second preferred structure of the resonance unit and including a step-down unit;

[0106] Figure 8 This is a schematic diagram of the structure of the second preferred structure of the power factor correction unit in the embodiment of the present application, combined with the second preferred structure of the resonance unit and including a step-down unit;

[0107] Figure 9This is a structural diagram of a vehicle-mounted charger according to an embodiment of the present application;

[0108] Figure 10 It is a schematic structural diagram of the power module 2 in the embodiment of the present application. DETAILED DESCRIPTION

[0109] To make the above-mentioned objects, features and advantages of the present application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present application and are only part of the embodiments of the present application, not all of them, and are not intended to limit the present application.

[0110] The inventors found that the on-board chargers of electric vehicles are basically divided into two major structures: PFC (Power Factor Correction) and LLC (Resonant Converter). Among them, the electrolytic capacitor used for voltage stabilization in PFC occupies a relatively large volume, for example: Figure 1 The figure shows a conventional on-board charger structure, where 16 represents electrolytic capacitors. It can be seen that there are many of them and they occupy a large volume, which greatly affects the improvement of power density and indirectly leads to an increase in cost, which is very unfavorable for the miniaturization and cost reduction of the on-board charger.

[0111] In addition, the inventors further discovered that in current on-board chargers, whether in PFC or LLC structures, MOS tubes (Metal-Oxide-Semiconductor Field-Effect Transistor, abbreviated as MOSFET, Chinese: Metal-Oxide-Semiconductor Field-Effect Transistor) are used as their switching tubes, and these MOS tubes are all discrete. For example: Figure 2 The heat dissipation structure of a conventional on-board charger is shown. In this structure, a spring piece 5 is crimped with a bolt 6, and then the MOS tube is fixed on a heat sink 3 for heat dissipation. The assembly process is relatively complicated, the production line operation is inconvenient, and the heat dissipation effect is relatively poor, which affects the stability of the switching tube during production and use.

[0112] In response to the above problems, the inventors, after in-depth research, creatively proposed a charging circuit, an onboard charger, and a vehicle of the present application, which effectively solve the above problems. The technical solution of the present application is explained and illustrated in detail below.

[0113] The present application provides a charging circuit, which is applied to a scenario where an AC power supply provides AC power to charge a load. The charging circuit includes: a power factor correction unit, a resonance unit; Figure 3In the modular schematic diagram of the charging circuit shown, the input of the power factor correction unit is electrically connected to an external power source, and the output is electrically connected to the input of the resonance unit; the output of the resonance unit is electrically connected to a load. The load can include any device capable of receiving and storing electrical energy, such as a power battery commonly used in electric vehicles.

[0114] The charging circuit of the present application creatively does not have a voltage stabilizing capacitor in the power factor correction unit. However, the traditional PFC structure has multiple voltage stabilizing capacitors (i.e. Figure 1 The reason for including a voltage-stabilizing capacitor is that traditional technology prejudges the need for stable DC power. Typically, a traditional PFC rectifies and boosts the voltage of an external power source to stable DC power. The LLC then regulates this stable DC power using varying switching frequencies to achieve a stable, suitable voltage range for charging the load. For example, assuming an external power source provides 220V AC power, the PFC rectifies and boosts this 220V AC power to a stable 400V DC voltage. The LLC then regulates this stable 400V DC voltage using varying switching frequencies to achieve a stable, suitable voltage range of 400V to 600V for charging the load.

[0115] However, in the charging circuit of the present application, the power factor correction unit does not have a voltage-stabilizing capacitor. The power factor correction unit is configured to rectify and boost the voltage from the external power supply to generate a fluctuating output voltage to the resonant unit. That is, the voltage output by the power factor correction unit of the present application to the resonant unit is a fluctuating DC voltage with ripples. Continuing with the above example: the external power supply provides 220V AC power, and the 220V AC power is rectified and boosted by the power factor correction unit to a fluctuating DC voltage of 300V to 400V with ripples. The resonant unit is configured to regulate the output voltage with a fixed transformation ratio to generate a fluctuating voltage to charge the load. That is, the switching frequency of the resonant unit is fixed, not variable, so it regulates the voltage output by the power factor correction unit with a fixed transformation ratio; for example, the power factor correction unit outputs a fluctuating, rippled 300V~400V DC voltage to the resonant unit, and the resonant unit uses a fixed switching frequency and transformer transformation ratio to regulate the voltage, for example, boosting the voltage by 1.5 times, then a fluctuating, rippled voltage range of 450V~600V is obtained to charge the load.

[0116] The resonant unit of the present application outputs a fluctuating voltage with ripples. Since the output of the resonant unit is connected to the load, and the load can be equivalently regarded as a large capacitor device with a very high capacitance value, and the characteristics of the capacitor device itself determine that it can clamp the fluctuating voltage with ripples very well, so it can ensure that the fluctuating voltage output by the resonant unit forms a stable DC voltage while not affecting the service life of the load itself.

[0117] This application creatively breaks the prejudice of traditional technology and cleverly utilizes the characteristic that the load itself can be equivalent to a large capacitor (especially the fact that the capacity of power batteries, which are currently the typical load, is getting larger and larger, and the voltage level is getting higher and higher, which shows the characteristic of larger capacitance). It directly eliminates the electrolytic capacitor, significantly reduces the volume cost, and saves a lot of cost, which is very conducive to the miniaturization and cost reduction of vehicle chargers. At the same time, because the frequency of the switching tube in the resonant unit is fixed, there is no need to adjust the voltage range by adjusting the frequency, so the drive control (that is, the control logic) is simpler.

[0118] In one embodiment of the present application, considering that the resonant unit outputs a fluctuating voltage with ripples, which may affect the electromagnetic compatibility of the entire charging circuit, the preferred charging circuit further includes: a filtering unit. Figure 4 A modular schematic diagram of a preferred charging circuit is shown, in which a filter unit is arranged between the input end of the power factor correction unit and the output end of the external voltage. The filter unit is used to filter and stabilize the voltage output by the external voltage, or to filter and stabilize the voltage transmitted in the reverse direction of the load, thereby meeting the electromagnetic compatibility design requirements.

[0119] In the charging circuit proposed in this application, there are various structures of the power factor correction unit and the resonant unit. The following only exemplifies several preferred structural forms. Those skilled in the art can derive other structures by simple transformation or reasoning based on the exemplified structural forms. No detailed description is given here.

[0120] The first preferred structural form of the power factor correction unit in this application is:

[0121] The power factor correction unit includes: a first bridge arm, a second bridge arm, and a third bridge arm; the first end of the first bridge arm is electrically connected to the first end of the second bridge arm, the first end of the third bridge arm, and the first end of the resonance unit respectively; the second end of the first bridge arm is electrically connected to the second end of the second bridge arm, the second end of the third bridge arm, and the second end of the resonance unit respectively.

[0122] The third end of the first bridge arm is electrically connected to the first phase line of the external power supply; the third end of the second bridge arm is electrically connected to the second phase line of the external power supply; and the third end of the third bridge arm is electrically connected to the neutral line of the external power supply. The external power supply is a single-phase power supply, and the first phase line and the second phase line are obtained by dividing a phase line of the external power supply into two paths. Generally speaking, each bridge arm is formed by two MOS tubes connected in series, and the third end of the bridge arm refers to the series connection node of the two series-connected MOS tubes. This first structure can be regarded as the structure of a power factor correction unit when the external power supply is a single-phase power supply. Generally, a single-phase power supply has only one live wire L and one neutral wire N. Then, the live wire L is divided into two paths, one path L1 is electrically connected to the third end of the first bridge arm, and the other path L2 is electrically connected to the third end of the second bridge arm. The remaining neutral wire N is electrically connected to the third end of the third bridge arm.

[0123] In addition, if there is a boost requirement, the power factor correction unit also needs to include: a first inductor and a second inductor; the first end of the first inductor is electrically connected to the first phase line, and the second end is electrically connected to the third end of the first bridge arm; the first end of the second inductor is electrically connected to the second phase line, and the second end is electrically connected to the third end of the second bridge arm, that is, the first inductor is arranged between the first phase line L1 and the first bridge arm, and the second inductor is arranged between the second phase line L2 and the second bridge arm.

[0124] The first and second inductors, along with the first and second bridge arms, form a boost structure. The voltage from the external power supply is boosted by varying the duty cycle of the switches in the first and second arms. The switching frequency of the switches in the third arm is the same as the external power supply frequency, meaning its duty cycle is 0.5. By varying the on and off cycles of the switches in the third arm, the voltage from the external power supply is rectified.

[0125] The second preferred structural form of the power factor correction unit in this application is:

[0126] The power factor correction unit includes: a first bridge arm, a second bridge arm, a third bridge arm, and a fourth bridge arm; the first end of the first bridge arm is electrically connected to the first end of the second bridge arm, the first end of the third bridge arm, the first end of the fourth bridge arm, and the first end of the resonance unit respectively; the second end of the first bridge arm is electrically connected to the second end of the second bridge arm, the second end of the third bridge arm, the second end of the fourth bridge arm, and the second end of the resonance unit respectively.

[0127] The third end of the first bridge arm is electrically connected to the first phase line of the external power supply; the third end of the second bridge arm is electrically connected to the second phase line of the external power supply; the third end of the third bridge arm is electrically connected to the third phase line of the external power supply; and the third end of the fourth bridge arm is electrically connected to the neutral line of the external power supply. The external power supply is a three-phase power supply, which provides a first phase line, a second phase line, and a third phase line, respectively. This second structure can be regarded as the structure of a power factor correction unit when the external power supply is a three-phase power supply. Generally, a three-phase power supply has three live wires L1, L2, and L3 and a neutral wire N. Then, each live wire is electrically connected to the third end of a corresponding bridge arm, and the remaining neutral wire N is electrically connected to the third end of the fourth bridge arm.

[0128] Similarly, if a voltage boost is required, the power factor correction unit also needs to include: a first inductor, a second inductor, and a third inductor; the first end of the first inductor is electrically connected to the first phase line, and the second end is electrically connected to the third end of the first bridge arm; the first end of the second inductor is electrically connected to the second phase line, and the second end is electrically connected to the third end of the second bridge arm; the first end of the third inductor is electrically connected to the third phase line, and the second end is electrically connected to the third end of the third bridge arm. In other words, the first inductor is arranged between the first phase line L1 and the first bridge arm, the second inductor is arranged between the second phase line L2 and the second bridge arm, and the third inductor is arranged between the third phase line L3 and the third bridge arm.

[0129] The first, second, and third inductors, along with the first, second, and third bridge arms, form a boost structure. The voltage from the external power supply is boosted by varying the duty cycle of the switches in each of the first, second, and third arms. The switching frequency of the switches in the fourth arm is the same as the frequency of the external power supply, meaning its duty cycle is 0.5. By varying the on and off cycles of the switches in the fourth arm, the voltage from the external power supply is rectified.

[0130] The first preferred structural form of the resonant unit in this application is:

[0131] The resonant unit includes: a fifth bridge arm, a sixth bridge arm, a seventh bridge arm, an eighth bridge arm, a first capacitor, a fourth inductor, and a transformer. The first end of the fifth bridge arm and the first end of the sixth bridge arm are both electrically connected to the first end of the power factor correction unit; and the second end of the fifth bridge arm and the second end of the sixth bridge arm are both electrically connected to the second end of the power factor correction unit.

[0132] The first end of the first capacitor is electrically connected to the third end of the fifth bridge arm, and the second end is electrically connected to the primary side of the transformer. The first end of the fourth inductor is electrically connected to the third end of the sixth bridge arm, and the second end is electrically connected to the primary side of the transformer. The secondary side of the transformer is electrically connected to the third end of the seventh bridge arm and the third end of the eighth bridge arm, respectively. The first end of the seventh bridge arm is electrically connected to the first end of the eighth bridge arm and the first end of the load, respectively. The second end of the seventh bridge arm is electrically connected to the second end of the eighth bridge arm and the second end of the load, respectively.

[0133] The switching frequency of each switching tube in the fifth bridge arm and the sixth bridge arm is fixed to a preset frequency (the preset frequency is an empirical value obtained through a large number of tests, and the optimal value may be: 180kHz). By changing the conduction and disconnection of the switching tube, the fluctuating output voltage is inverted in combination with the first capacitor and the fourth inductor to obtain a fluctuating inverter voltage.

[0134] The transformer is configured to transform the fluctuating inverter voltage to obtain a regulated fluctuating inverter voltage; by changing the conduction and disconnection of the respective switching tubes in the seventh bridge arm and the eighth bridge arm, the fluctuating inverter voltage is rectified to obtain a fluctuating voltage.

[0135] The first preferred structural form of the above-mentioned resonant unit can realize charging of the load, but considering actual needs, the load may also need to output electrical energy under certain conditions. Therefore, the second preferred structural form of the resonant unit in this application is proposed:

[0136] The resonant unit includes: a fifth bridge arm, a sixth bridge arm, a seventh bridge arm, an eighth bridge arm, a first capacitor, a second capacitor, a fourth inductor, a fifth inductor, and a transformer. The first end of the fifth bridge arm and the first end of the sixth bridge arm are both electrically connected to the first end of the power factor correction unit; the second end of the fifth bridge arm and the second end of the sixth bridge arm are both electrically connected to the second end of the power factor correction unit.

[0137] The first end of the first capacitor is electrically connected to the third end of the fifth bridge arm, and the second end is electrically connected to the primary side of the transformer; the first end of the fourth inductor is electrically connected to the third end of the sixth bridge arm, and the second end is electrically connected to the primary side of the transformer; the secondary side of the transformer is electrically connected to the first end of the second capacitor and the first end of the fifth inductor, respectively.

[0138] The second end of the fifth inductor is electrically connected to the third end of the seventh bridge arm; the second end of the second capacitor is electrically connected to the third end of the eighth bridge arm; the first end of the seventh bridge arm is electrically connected to the first end of the eighth bridge arm and the first end of the load respectively; the second end of the seventh bridge arm is electrically connected to the second end of the eighth bridge arm and the second end of the load respectively.

[0139] When the load is charged, the switching frequency of each switch tube in the fifth bridge arm and the sixth bridge arm is fixed to a preset frequency. By changing the on and off states of the switch tubes, the output voltage is inverted in combination with the first capacitor and the fourth inductor to obtain a fluctuating inverter voltage; the transformer transforms the inverter voltage to obtain a fluctuating inverter voltage after voltage regulation; by changing the on and off states of each switch tube in the seventh bridge arm and the eighth bridge arm, the fluctuating inverter voltage is rectified in combination with the second capacitor and the fifth inductor to obtain a fluctuating voltage.

[0140] When the load is discharged, that is, when the load outputs the industrial frequency AC voltage through the charging circuit, the stable voltage continuously generated by the load is inverted into a stable inverter voltage after passing through the seventh bridge arm, the eighth bridge arm, the second capacitor, and the fifth inductor; the stable inverter voltage is rectified into a stable rectified voltage after passing through the fifth bridge arm and the sixth bridge arm; the stable rectified voltage is inverted into an industrial frequency AC voltage after passing through the power factor calibration unit and output.

[0141] The structural forms of the power factor correction unit and the resonance unit listed above can be used in any combination to form a charging circuit. For example: the first preferred structure of the power factor correction unit combined with the first preferred structure of the resonance unit can obtain a charging circuit for charging the load when the external power supply is a single-phase power supply; the first preferred structure of the power factor correction unit combined with the second preferred structure of the resonance unit can obtain a charging circuit for charging the load when the external power supply is a single-phase power supply, and the load can output an industrial frequency AC voltage to the outside; the second preferred structure of the power factor correction unit combined with the second preferred structure of the resonance unit can obtain a charging circuit for charging the load when the external power supply is a three-phase power supply, and the load can output an industrial frequency AC voltage to the outside, and so on.

[0142] In addition, for electric vehicles, there is generally a step-down unit (ie DC-DC), so the charging circuit also includes: a step-down unit; Figure 5 The diagram shows a modular schematic of a charging circuit that includes a step-down unit. The step-down unit is used to step down fluctuating voltages to power low-voltage devices, or to step down the stable voltage generated by a load to power low-voltage devices. Low-voltage devices generally include in-vehicle batteries, air conditioners, and vehicle computers, among other low-voltage devices.

[0143] Preferably, the step-down unit includes: multiple inverter bridge arms, a step-down transformer, multiple rectifier bridge arms, and a voltage-stabilizing capacitor; the first ends of the multiple inverter bridge arms are electrically connected to the first end of the resonant unit, and the second ends are electrically connected to the second end of the resonant unit; the third end of each inverter bridge arm is electrically connected to the primary side of the step-down transformer.

[0144] The secondary side of the step-down transformer is electrically connected to the first ends of multiple rectifier bridge arms, the first end of the voltage-stabilizing capacitor, and the first end of the low-voltage device respectively; the second ends of the multiple rectifier bridge arms are electrically connected to the second end of the voltage-stabilizing capacitor and the second end of the low-voltage device.

[0145] Among them, multiple inverter bridge arms are used to invert the fluctuating voltage (when the external power supply provides voltage) or the stable voltage (when the load provides voltage); the step-down transformer is used to step down the fluctuating voltage after inversion or the stable voltage after inversion to obtain a fluctuating step-down voltage or a stable step-down voltage; multiple rectifier bridge arms are combined with the voltage-stabilizing capacitor to rectify the fluctuating step-down voltage or the stable step-down voltage to obtain a stable rectified voltage to power the low-voltage equipment.

[0146] In order to better understand the above structure, refer to Figure 6 The first preferred structure of the power factor correction unit shown above is combined with the first preferred structure of the resonant unit and includes a structural schematic diagram of the step-down unit. The external power supply is a single-phase power supply. The live wire L is divided into two paths, which are respectively connected to the first inductor L1 and the second inductor L2. The first inductor L1 is connected to the switching tubes Q1 and Q2 (Q1 and Q2 form the first bridge arm), and the second inductor L2 is connected to the switching tubes Q3 and Q4 (Q3 and Q4 form the second bridge arm). The neutral wire N of the single-phase power supply is connected to the switching tubes Q5 and Q6 (Q5 and Q6 form the third bridge arm). Among them, Q1, Q2, Q3, and Q4 are high-frequency tubes, commonly known as fast tubes, and Q5 and Q6 are industrial frequency tubes, commonly known as slow tubes. The above parts constitute a power factor correction circuit.

[0147] The first inductor L1, the second inductor L2, and the switches Q1, Q2, Q3, and Q4 form a boost circuit. By varying the duty cycle of switches Q1, Q2, Q3, and Q4, the output voltage of the power factor correction unit can be adjusted. Switches Q5 and Q6 operate at the same switching frequency as the external power supply, with a duty cycle of 0.5. Switch Q5 conducts during the negative half-cycle of the external power supply voltage, while switch Q6 conducts during the positive half-cycle, rectifying the AC power output from the external power supply into DC power.

[0148] The resonant unit is composed of switching tubes Q7, Q8 (Q7, Q8 form the fifth bridge arm), Q9, Q10 (Q9, Q10 form the sixth bridge arm), Q11, Q12 (Q11, Q12 form the seventh bridge arm), Q13, Q14 (Q13, Q14 form the eighth bridge arm), a first capacitor C1, a transformer T1, and a fourth inductor L4. The switching frequency of the switching tubes Q7, Q8, Q9, and Q10 is fixed. At this switching frequency, the fluctuating DC power output by the power factor correction unit is converted into sinusoidal AC power under the action of the first capacitor C1, the transformer T1, and the fourth inductor L4. After being rectified by the switching tubes Q11, Q12, Q13, and Q14, it is converted into fluctuating DC power and output to the load. Figure 6 The power battery BAT is used to represent the load.

[0149] In the step-down unit, the fluctuating voltage is inverted into AC power by switches Q15, Q16, Q17, and Q18. After being transformed by transformer T2, it is rectified by switches Q19, Q20, Q21, Q22, Q23, Q24, Q25, and Q26 to output a low-voltage DC voltage, which charges the vehicle's battery and low-voltage equipment (denoted by R in the figure). The step-down unit can also operate in reverse mode. The low-voltage DC voltage output by the battery is inverted by switches Q19, Q20, Q21, Q22, Q23, Q24, Q25, and Q26, transformed by transformer T2, and then rectified by switches Q15, Q16, Q17, and Q18 to output a high-voltage DC voltage in reverse.

[0150] Reference Figure 7 The schematic diagram shows a structure of the first preferred structure of the power factor correction unit combined with the second preferred structure of the resonance unit and including a step-down unit. Figure 7 and Figure 6 The difference is that the resonant unit adds a second capacitor C2 and a fifth inductor L5 on the secondary side of the transformer T1 to achieve the reverse function of the charging circuit. Figure 7 The power battery BAT represents the load, and the DC voltage generated by it is inverted into a high-frequency sinusoidal AC voltage through the switch tubes Q11, Q12, Q13, Q14, the second capacitor C2, the fifth inductor L5, and the transformer T1, and then rectified into a DC voltage through the switch tubes Q7, Q8, Q9, and Q10, and then inverted into a power frequency AC voltage through the switch tubes Q1, Q2, Q3, Q4, Q5, and Q6 for output. The rest of the structure is the same as Figure 6 Same, no more details.

[0151] Reference Figure 8 The schematic diagram of the structure of the second preferred structure of the power factor correction unit shown above is combined with the second preferred structure of the resonance unit and includes a step-down unit. Figure 8 and Figure 7 The difference is that the external power supply is a three-phase power supply, the input of the power factor correction unit is a three-phase AC power, and the switch tubes Q1, Q2, Q3, Q4, Q5, Q6, the first inductor L1, the second inductor L2, and the third inductor L3 are used to boost the three-phase AC voltage, and the switch tubes Q7, Q8 ( Figure 8 Q7 and Q8 form the fourth bridge arm; Q9 and Q10 form the fifth bridge arm; Q11 and Q12 form the sixth bridge arm; Q12 and Q14 form the seventh bridge arm; Q15 and Q16 form the eighth bridge arm) for rectification and output of boosted DC voltage. Figure 7 Same, no more details.

[0152] The above explains and illustrates the charging circuit that omits the electrolytic capacitor. In order to solve the problem that the aforementioned switching tube is discrete and not conducive to heat dissipation, based on the above charging circuit, the embodiment of the present application also proposes an on-board charger, which includes: a charging circuit as described in any of the above items.

[0153] Preferably, the on-board charger includes: a power module, the power module is partially immersed in the water channel, the power module is integrated with a target switch tube, the target switch tube includes all the switch tubes in the power factor correction unit and the resonant unit, and also includes all the switch tubes in the step-down unit. Figure 6 、 7 Middle switch tubes Q1~Q26, or Figure 8 The middle switching tubes Q1 to Q28 are all integrated in the power module.

[0154] Preferably, the on-board charger further includes: a power board.

[0155] The power module also integrates a driver chip, which is controlled by the power board and controls the on and off of each switch tube.

[0156] The power board is connected to the power module. The power board integrates a control chip, which is used to control all switching tubes in the power factor correction unit, resonant unit, and step-down unit to realize the function of the on-board charger.

[0157] For the on-board charger, in order to realize the corresponding functions, it also includes: filter board, auxiliary source drive board and magnetic devices. Figure 9 The structural diagram of a vehicle charger is shown in FIG. Figure 9 The system includes a power board 1, a power module 2, a filter board 4, an auxiliary power driver board 5, magnetic components 6, and a water channel 3. The filter board 4 and magnetic components 6 are integrated and connected to the control board 1. The filter board 4 is used to filter and stabilize the voltage output by the external power supply or the load. The filter board is the aforementioned filter unit.

[0158] The auxiliary source driver board 5 is connected to the power board 1 and the power module 2 respectively, and is used to provide the required low voltage for the power board 1 and the driver chip. Generally, it is 12V; the magnetic components include: the inductor in the power factor correction unit ( Figure 6 、 7 The first inductor L1, the second inductor L2), the transformer in the resonant unit ( Figure 6 、 7 , T1 in 8) and the transformer in the step-down unit ( Figure 6 、 7 , 8 in T2);

[0159] The power board 1 is connected to the power module 2. In addition to the integrated control chip, the power board 1 also integrates other parts for controlling all the switch tubes in the power factor correction unit and the resonant unit to realize the function of the on-board charger. That is, the main function of the charging circuit is realized by the power board 1. Among them, the so-called other parts of the power board 1 include: sampling structure, communication structure, power factor correction unit, resonant unit and the remaining structures in the step-down unit except the switch tube, inductor and transformer (such as Figure 6 The first capacitor C1 and the fourth inductor L4; Figure 7 The first capacitor C1, the second capacitor C2, the fourth inductor L4, the fourth and fifth inductors L5, etc.).

[0160] The power module 2 is directly attached to the water channel 3 and partially immersed in the water channel. Figure 10 The power module 2 shown in the figure comprises an overcurrent terminal 21 , a plastic package housing 22 , a heat dissipation base plate 23 , and a signal terminal 24 .

[0161] After integration, the switching tube is encapsulated in a plastic casing 22; the heat dissipation base plate 23 serves as the bottom of the power module 2, is installed on the outside of the plastic casing 22, and is immersed in the water channel 3; the overcurrent terminal 21 extends out of the plastic casing 22 and is used to connect to the low-voltage equipment in the vehicle (that is, the external low-voltage and high-current load) to ensure the normal operation of the external low-voltage load; the signal terminal 24 extends out of the plastic casing 22 and is used to connect to the power board 1.

[0162] Preferably, the heat sink base plate 23 is provided with comb-like teeth that are embedded in the water channel 3 and become part of it. Coolant flows through the heat sink base plate 23 and the comb-like teeth to achieve convection heat dissipation, which facilitates sufficient heat dissipation of the power module 2. The assembly process is relatively simple, and the production line is convenient. The plastic housing 22 is preferably made of epoxy resin, which integrally encapsulates the power module 2 and has high heat resistance and reliability.

[0163] Based on the above-mentioned charging circuit, the embodiment of the present application also proposes a vehicle, which includes: the above-mentioned on-board charger of the present application. Through the above-mentioned embodiment, the charging circuit, on-board charger and vehicle proposed in the present application directly eliminate the electrolytic capacitor, utilize the characteristics of the load itself, break the prejudice of the prior art, and directly use the fluctuating voltage to charge the load, which significantly reduces the volume cost and saves a lot of cost, which is very beneficial to the miniaturization and cost reduction of the on-board charger. At the same time, since the frequency of the switching tube in the resonant unit is fixed, there is no need to adjust the voltage range by adjusting the frequency, so the drive control (that is, the control logic) is simpler. And all the switching tubes are integrated and packaged into a power module, which is more conducive to the convection heat dissipation of the coolant. While fully dissipating the heat, its assembly process is relatively simple, the production line operation is convenient, and it has high practicality.

[0164] Although preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they become aware of the basic inventive concepts. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present invention.

[0165] Finally, it should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that includes a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or terminal device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of additional identical elements in the process, method, article, or terminal device that includes the element.

[0166] The embodiments of the present application are described above in conjunction with the accompanying drawings and are introduced in detail. Specific examples are used herein to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea. At the same time, for those skilled in the art, according to the ideas of the present application, there may be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present application.

Claims

1. A charging circuit, characterized in that: The charging circuit includes: a power factor correction unit and a resonance unit; The input end of the power factor correction unit is electrically connected to the external power supply, and the output end is electrically connected to the input end of the resonance unit; The output end of the resonant unit is electrically connected to the load; The power factor correction unit is configured to rectify and boost the voltage from the external power supply to generate a fluctuating output voltage to the resonance unit; The resonant unit is configured to regulate the output voltage with a fixed transformation ratio to generate a fluctuating voltage for charging the load.

2. The charging circuit according to claim 1, wherein: The power factor correction unit includes: a first bridge arm, a second bridge arm, and a third bridge arm; The first end of the first bridge arm is electrically connected to the first end of the second bridge arm, the first end of the third bridge arm, and the first end of the resonant unit respectively; The second end of the first bridge arm is electrically connected to the second end of the second bridge arm, the second end of the third bridge arm, and the second end of the resonant unit respectively; The third end of the first bridge arm is electrically connected to the first phase line of the external power supply; The third end of the second bridge arm is electrically connected to the second phase line of the external power supply; The third end of the third bridge arm is electrically connected to the neutral line of the external power supply; The external power supply is a single-phase power supply, and the first phase line and the second phase line are obtained by dividing one phase line of the external power supply into two phases.

3. The charging circuit according to claim 2, wherein: The power factor correction unit further includes: a first inductor and a second inductor; A first end of the first inductor is electrically connected to the first phase line, and a second end of the first inductor is electrically connected to the third end of the first bridge arm; A first end of the second inductor is electrically connected to the second phase line, and a second end of the second inductor is electrically connected to the third end of the second bridge arm; The first inductor, the second inductor, the first bridge arm, and the second bridge arm form a boost structure, and the voltage from the external power supply is boosted by changing the duty cycle of the respective switching tubes in the first bridge arm and the second bridge arm; The switching frequency of the switch tube in the third bridge arm is the same as the frequency of the external power supply. By changing the on and off of the switch tube in the third bridge arm, the voltage from the external power supply is rectified.

4. The charging circuit according to claim 1, wherein: The power factor correction unit includes: the power factor correction unit includes: a first bridge arm, a second bridge arm, a third bridge arm, and a fourth bridge arm; The first end of the first bridge arm is electrically connected to the first end of the second bridge arm, the first end of the third bridge arm, the first end of the fourth bridge arm, and the first end of the resonant unit respectively; The second end of the first bridge arm is electrically connected to the second end of the second bridge arm, the second end of the third bridge arm, the second end of the fourth bridge arm, and the second end of the resonant unit respectively; The third end of the first bridge arm is electrically connected to the first phase line of the external power supply; The third end of the second bridge arm is electrically connected to the second phase line of the external power supply; The third end of the third bridge arm is electrically connected to the third phase line of the external power supply; The third end of the fourth bridge arm is electrically connected to the neutral line of the external power supply The external power supply is a three-phase power supply, which provides the first phase line, the second phase line and the third phase line respectively.

5. The charging circuit according to claim 4, characterized in that: The power factor correction unit further includes: a first inductor, a second inductor, and a third inductor; A first end of the first inductor is electrically connected to the first phase line, and a second end of the first inductor is electrically connected to the third end of the first bridge arm; A first end of the second inductor is electrically connected to the second phase line, and a second end of the second inductor is electrically connected to the third end of the second bridge arm; A first end of the third inductor is electrically connected to the third phase line, and a second end of the third inductor is electrically connected to the third end of the third bridge arm; The first inductor, the second inductor, the third inductor, the first bridge arm, the second bridge arm, and the third bridge arm form a boost structure, and the voltage from the external power supply is boosted by changing the duty cycle of the respective switching tubes in the first bridge arm, the second bridge arm, and the third bridge arm; The switching frequency of the switch tube in the fourth bridge arm is the same as the frequency of the external power supply. By changing the on and off of the switch tube in the fourth bridge arm, the voltage from the external power supply is rectified.

6. The charging circuit according to claim 1, wherein: The resonant unit includes: a fifth bridge arm, a sixth bridge arm, a seventh bridge arm, an eighth bridge arm, a first capacitor, a fourth inductor, and a transformer; The first end of the fifth bridge arm and the first end of the sixth bridge arm are both electrically connected to the first end of the power factor correction unit; The second end of the fifth bridge arm and the second end of the sixth bridge arm are both electrically connected to the second end of the power factor correction unit; The first end of the first capacitor is electrically connected to the third end of the fifth bridge arm, and the second end is electrically connected to the primary side of the transformer; The first end of the fourth inductor is electrically connected to the third end of the sixth bridge arm, and the second end is electrically connected to the primary side of the transformer; The secondary side of the transformer is electrically connected to the third end of the seventh bridge arm and the third end of the eighth bridge arm respectively; The first end of the seventh bridge arm is electrically connected to the first end of the eighth bridge arm and the first end of the load respectively; The second end of the seventh bridge arm is electrically connected to the second end of the eighth bridge arm and the second end of the load respectively.

7. The charging circuit according to claim 6, wherein: The switching frequency of each switch in the fifth bridge arm and the sixth bridge arm is fixed to a preset frequency, and the output voltage is inverted in combination with the first capacitor and the fourth inductor by changing the on and off states of the switch to obtain a fluctuating inverter voltage; The transformer is configured to transform the inverter voltage to obtain a voltage-regulated fluctuating inverter voltage; The fluctuating inverter voltage is rectified by changing the on and off states of the respective switching tubes in the seventh bridge arm and the eighth bridge arm to obtain the fluctuating voltage.

8. The charging circuit according to claim 1, wherein: The resonant unit includes: the resonant unit includes: a fifth bridge arm, a sixth bridge arm, a seventh bridge arm, an eighth bridge arm, a first capacitor, a second capacitor, a fourth inductor, a fifth inductor, and a transformer; The first end of the fifth bridge arm and the first end of the sixth bridge arm are both electrically connected to the first end of the power factor correction unit; The second end of the fifth bridge arm and the second end of the sixth bridge arm are both electrically connected to the second end of the power factor correction unit; The first end of the first capacitor is electrically connected to the third end of the fifth bridge arm, and the second end is electrically connected to the primary side of the transformer; The first end of the fourth inductor is electrically connected to the third end of the sixth bridge arm, and the second end is electrically connected to the primary side of the transformer; The secondary side of the transformer is electrically connected to the first end of the second capacitor and the first end of the fifth inductor respectively; The second end of the fifth inductor is electrically connected to the third end of the seventh bridge arm; The second end of the second capacitor is electrically connected to the third end of the eighth bridge arm; The first end of the seventh bridge arm is electrically connected to the first end of the eighth bridge arm and the first end of the load respectively; The second end of the seventh bridge arm is electrically connected to the second end of the eighth bridge arm and the second end of the load respectively.

9. The charging circuit according to claim 8, characterized in that: When the load is charged, the switching frequency of each switch tube in the fifth bridge arm and the sixth bridge arm is fixed to a preset frequency, and the output voltage is inverted in combination with the first capacitor and the fourth inductor by changing the on and off states of the switch tubes to obtain a fluctuating inverter voltage; The transformer is configured to transform the inverter voltage to obtain a voltage-regulated fluctuating inverter voltage; The fluctuating voltage is obtained by changing the on and off states of the respective switching tubes in the seventh bridge arm and the eighth bridge arm and rectifying the fluctuating inverter voltage in combination with the second capacitor and the fifth inductor.

10. The charging circuit according to claim 8, wherein: When the load is discharged, the stable voltage continuously generated by the load is inverted into a stable inverter voltage after passing through the seventh bridge arm, the eighth bridge arm, the second capacitor, and the fifth inductor; The stable inverter voltage is rectified into a stable rectified voltage after passing through the fifth bridge arm and the sixth bridge arm; The stable rectified voltage is inverted into an industrial frequency AC voltage after passing through the power factor calibration unit and output.

11. The charging circuit according to claim 1, wherein: The charging circuit further includes: a step-down unit; The step-down unit is used to step down the fluctuating voltage to supply power to low-voltage equipment; or The step-down unit is used to step down the stable voltage generated by the load to supply power to the low-voltage device.

12. The charging circuit according to claim 11, wherein: The step-down unit includes: multiple inverter bridge arms, a step-down transformer, multiple rectifier bridge arms, and a voltage stabilizing capacitor; The first ends of the plurality of inverter bridge arms are electrically connected to the first end of the resonance unit, and the second ends thereof are electrically connected to the second end of the resonance unit; The third end of each inverter bridge arm is electrically connected to the primary side of the step-down transformer; The secondary side of the step-down transformer is electrically connected to the first ends of the plurality of rectifier bridge arms, the first end of the voltage stabilizing capacitor, and the first end of the low-voltage device respectively; The second ends of the plurality of rectifier bridge arms are electrically connected to the second end of the voltage stabilizing capacitor and the second end of the low-voltage device; Wherein, the multiple inverter bridge arms are used to invert the fluctuating voltage or the stable voltage; The step-down transformer is used to step down the fluctuating voltage after inversion or the stable voltage after inversion to obtain a fluctuating step-down voltage or a stable step-down voltage; The multiple rectifier bridge arms, in combination with the voltage-stabilizing capacitor, rectify the fluctuating step-down voltage or the stable step-down voltage to obtain a stable rectified voltage to power the low-voltage device.

13. The charging circuit according to claim 1, wherein: The charging circuit further includes: a filtering unit; The filtering unit is arranged between the input end of the power factor correction unit and the output end of the external voltage, and is used to filter and stabilize the voltage output by the external voltage, or to filter and stabilize the voltage transmitted in reverse by the load.

14. The charging circuit according to claim 1, wherein: The load includes: a device having the function of receiving and storing electric energy.

15. A vehicle-mounted charger, characterized in that: The on-board charger includes: a charging circuit as described in any one of claims 1-14.

16. The on-vehicle charger according to claim 15, characterized in that: include: A power module is partially immersed in the water channel, and a target switch tube is integrated in the power module. The target switch tube includes all the switch tubes in the power factor correction unit and the resonant unit.

17. The on-vehicle charger according to claim 16, characterized in that: The target switch tube also includes all switch tubes in the step-down unit.

18. The on-board charger according to claims 15-16, characterized in that: The on-board charger includes: a power board; The power module also integrates a driver chip, which is controlled by the power board and controls the on and off of each switch tube; The power board is connected to the power module. The power board is integrated with a control chip for controlling all switching tubes in the power factor correction unit, the resonance unit, and the step-down unit to realize the function of the on-board charger.

19. The on-vehicle charger according to claim 16, characterized in that: The power module is directly attached to the water channel and partially immersed in the water channel; The power module includes: an overcurrent terminal, a plastic package shell, a heat dissipation base plate, and a signal terminal; The switch tube is integrated and packaged in the plastic housing; The heat dissipation base plate serves as the bottom of the power module, is installed on the outside of the plastic package shell, and is immersed in the water channel; The overcurrent terminal extends out of the plastic housing and is used to connect to low-voltage equipment in the vehicle; The signal terminal extends out of the plastic housing and is used to be connected to the power board.

20. The on-vehicle charger according to claim 19, characterized in that: The heat dissipation bottom plate is provided with comb-shaped teeth, and the comb-shaped teeth are embedded in the water channel and become a part of the water channel.

21. The on-vehicle charger according to claim 18, characterized in that The on-board charger further includes: a filter board, an auxiliary source drive board and a magnetic device; The filter board is integrated with the magnetic device and connected to the power board. The filter board is used to filter and stabilize the voltage output by the external power supply or the voltage output by the load. The auxiliary source driving board is connected to the power board and the power module respectively, and is used to provide the required low voltage to the power board and the driving chip; The magnetic device includes: an inductor in the power factor correction unit, a transformer in the resonance unit, and a transformer in the step-down unit; The power board is also integrated with other parts, including: a sampling structure, a communication structure, the power factor correction unit, the resonance unit, and the remaining structures of the step-down unit except the switch tube, the inductor, and the transformer.

22. A vehicle, characterized in that: The vehicle comprises: the on-board charger according to any one of claims 15-21.

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