Charging system and electric vehicle

Abstract

The invention provides a charging system and an electric vehicle, and relates to the technical field of electric vehicles, one end of a switch tube is suitable for being electrically connected with a charging port, and the other end is electrically connected with a first end of an inductive element; the second end of the inductive element is suitable for being electrically connected with the power battery through the bridge arm module; during boost charging, the inductive element and the bridge arm module form a boost charging loop, and the power battery is charged after the voltage received by the charging port is boosted. During voltage reduction charging, the inductive element and the bridge arm module form a voltage reduction charging loop, and the voltage received by the charging port is reduced to charge the power battery. According to the invention, few components are added, the boost-buck charging function is realized, and the charging compatibility and convenience of the electric vehicle are improved. The circuit is simple, the space occupancy rate is reduced, and meanwhile the cost of the electric automobile is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of electric vehicles, in particular to a charging system and an electric vehicle. Background Art

[0002] Most of the DC fast charging piles on the market currently have a limited output voltage range, while the voltage range of the power batteries of different models of electric vehicles is getting wider and wider, and the power required for charging is also uneven. Due to the differences in the output capacity of charging piles from different manufacturers, some high-voltage models cannot be charged at charging piles with low output voltage, or charging piles with high output voltage cannot output the maximum power to charge low-voltage electric vehicles. Summary of the invention

[0003] In view of the above problems, the present invention is proposed to provide a charging system and an electric vehicle that overcome the above problems or at least partially solve the above problems.

[0004] In a first aspect, a charging system is provided, the charging system comprising: a switch tube, an inductive element and a bridge arm module;

[0005] One end of the switch tube is suitable for being electrically connected to the charging port, and the other end is electrically connected to the first end of the inductive element;

[0006] The second end of the inductive element is suitable for being electrically connected to the power battery through the bridge arm module;

[0007] When the charging system operates in the boost charging mode, the working state of the switch tube is controlled, and the inductive element and the bridge arm module are used to form a boost charging circuit to increase the voltage received by the charging port to charge the power battery;

[0008] When the charging system operates in the step-down charging mode, the working state of the switch tube is controlled, and the inductive element and the bridge arm module are used to form a step-down charging circuit to charge the power battery after reducing the voltage received by the charging port.

[0009] Optionally, the switch tube includes: a first switch tube and a second switch tube;

[0010] The first end of the first switch tube is suitable for being electrically connected to the first end of the charging port;

[0011] The second end of the first switch tube is electrically connected to the first end of the inductive element;

[0012] The first end of the second switch tube is electrically connected to the first end of the inductive element;

[0013] The second end of the second switch tube is suitable for being electrically connected to the second end of the charging port.

[0014] Optionally, the second end of the first switch tube is electrically connected to the first end of the second switch tube, and the electrical connection point is electrically connected to the first end of the inductive element.

[0015] Optionally, when the charging system operates in a direct charging mode, the working state of the switch tube is controlled, and a direct charging loop is formed using the inductive element and the bridge arm module, and the power battery is directly charged using the voltage received by the charging port.

[0016] Optionally, the charging system further comprises: a filter capacitor;

[0017] One end of the filter capacitor is electrically connected to the first end of the inductive element, and the other end is electrically connected to the negative terminal of the bridge arm module;

[0018] The filter capacitor is used to filter the electric energy received by the charging port.

[0019] Optionally, the charging system further includes: a first contactor or a second contactor;

[0020] One end of the first contactor is electrically connected to the second end of the switch tube, and the other end is electrically connected to the first end of the inductive element;

[0021] The first contactor is used to control the on / off of the circuit between the second end of the switch tube and the first end of the inductive element;

[0022] One end of the second contactor is electrically connected to the negative end of the bridge arm module, and the other end is suitable for being electrically connected to the second end of the charging port;

[0023] The second contactor is used to control the on / off of the circuit between the charging port and the negative terminal of the bridge arm module.

[0024] Optionally, the first switch tube includes: a first field effect tube; the second switch tube includes: a second field effect tube;

[0025] The first end of the first field effect tube is suitable for being electrically connected to the first end of the charging port, the third end is suitable for receiving a first control signal, and the second end is electrically connected to the first end of the inductive element;

[0026] The first end of the second field effect tube is electrically connected to the first end of the inductive element, the third end is suitable for receiving the second control signal, and the second end is electrically connected to the second end of the charging port and the negative terminal of the power battery respectively.

[0027] Optionally, the inductive element includes: N-phase windings; the bridge arm module includes: N bridge arms connected in parallel;

[0028] The first end of the N-phase winding is electrically connected to the other end of the switch tube;

[0029] The second ends of the N-phase windings are connected to the midpoints of the N bridge arms in a one-to-one correspondence, where N is an integer greater than or equal to 1.

[0030] Optionally, when the charging system operates in the boost charging mode, the first switch tube is controlled to be closed, the second switch tube is controlled to be disconnected, and the upper bridges of the N bridge arms are controlled to be closed, and the lower bridge of at least one bridge arm is controlled to be turned on for a first preset time, so that the electric energy received by the charging port is used to charge the N-phase winding;

[0031] After the first preset time is turned on, the lower bridges of the N bridge arms are controlled to be closed and the upper bridge of at least one bridge arm is turned on, so that the charging port and the N-phase winding charge the power battery together;

[0032] The above process is repeated until charging is completed.

[0033] Optionally, when the charging system operates in the buck charging mode, in the first stage, the first switch tube is controlled to be closed, the second switch tube is disconnected, and the lower bridges of the N bridge arms are controlled to be closed and the upper bridge of at least one bridge arm is turned on, so that the charging port charges the N-phase winding and the power battery at the same time;

[0034] In the second stage, the first switch tube is controlled to be disconnected, the second switch tube is controlled to be closed, and the lower bridges of the N bridge arms are controlled to be closed, and the upper bridge of at least one bridge arm is controlled to be turned on, so that the N-phase winding is freewheeling to reduce the voltage and charge the power battery;

[0035] The above process is repeated until charging is completed.

[0036] Optionally, when the charging system operates in the direct charging mode, the first switch tube is controlled to be closed and the second switch tube is controlled to be disconnected, and the lower bridge of each of the N bridge arms is controlled to be closed and the upper bridge of at least one bridge arm is turned on, then the charging port, the three-phase winding and the upper bridge of each of the N bridge arms are used for direct charging of the power battery.

[0037] Optionally, the charging system further comprises: a pre-charge capacitor and a positive and negative switch of the power battery;

[0038] The pre-charge capacitor is electrically connected to the positive terminal and the negative terminal of the power battery;

[0039] When the charging system operates in the boost pre-charging mode, the first switch tube is controlled to be closed, the second switch tube is controlled to be disconnected, the positive and negative switches are controlled to be disconnected, and the upper bridges of the N bridge arms, the second bridge arm, and the third bridge arm are controlled to be closed, and the lower bridge of at least one bridge arm is controlled to be turned on for a second preset time, so that the electric energy received by the charging port or the electric energy provided by the in-vehicle power supply is used to charge the three-phase winding;

[0040] After the second preset time is turned on, the lower bridges of the N bridge arms are controlled to be closed and the upper bridge of at least one bridge arm is turned on, so that the electric energy received by the charging port or the electric energy provided by the in-vehicle power supply and the three-phase winding freewheeling are used to charge the pre-charge capacitor together, and this process is repeated until the voltage of the pre-charge capacitor differs from the current real-time voltage of the power battery within a preset range;

[0041] When the charging system operates in the buck pre-charging mode, in the first stage, the positive and negative switches are controlled to be disconnected, the first switch tube is closed, the second switch tube is disconnected, and the lower bridges of the N bridge arms are controlled to be closed and the upper bridge of at least one bridge arm is turned on, so that the electric energy received by the charging port or the electric energy provided by the in-vehicle power supply is used to charge the N-phase winding and the pre-charging capacitor at the same time;

[0042] In the second stage, the positive and negative switches are controlled to be disconnected, the first switch tube is disconnected, the second switch tube is closed, and the lower bridges of the N bridge arms are controlled to be closed and the upper bridge of at least one bridge arm is turned on, so that the N-phase winding continues to charge the pre-charge capacitor by freewheeling, and the process is repeated until the voltage of the pre-charge capacitor differs from the current real-time voltage of the power battery within a preset range;

[0043] When the charging system operates in the direct pre-charging mode, the first switch tube is controlled to be closed, the second switch tube is controlled to be disconnected, the positive and negative switches are controlled to be disconnected, and the lower bridges of the N bridge arms are controlled to be closed, and the upper bridge of at least one bridge arm is controlled to be turned on. Then, the electric energy received by the charging port or the electric energy provided by the in-vehicle power supply is input to the pre-charging capacitor through the N-phase winding and the upper bridges of the N bridge arms, and the pre-charging capacitor is directly charged until the voltage of the pre-charging capacitor differs from the current real-time voltage of the power battery within a preset range.

[0044] In a second aspect, an electric vehicle is provided, comprising: a charging system as described in the first aspect.

[0045] The embodiments of the present application have the following advantages:

[0046] In the present invention, a switch tube is creatively added, and the switch tube is electrically connected to the charging port and the inductive element. Only the switch tube is added, and the DC fast charging boost or buck module is no longer needed, thereby realizing the boost-boost charging function. That is, when boost charging is required, the inductive element and the bridge arm module are used to form a boost charging circuit, and the voltage received by the charging port is increased to charge the power battery, solving the problem of boosting the low-voltage charging pile to charge the electric vehicle; at the same time, when step-down charging is required, the inductive element and the bridge arm module are used to form a step-down charging circuit, and the voltage received by the charging port is reduced to charge the power battery. Through the above-mentioned boost and buck methods, the compatibility and convenience of electric vehicle charging are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0048] Figure 1 is a schematic diagram of a circuit structure of a charging system according to an embodiment of the present invention;

[0049] Figure 2 It is a schematic diagram of the circuit structure of a preferred charging system according to an embodiment of the present invention;

[0050] Figure 3 Schematic diagram of the current direction when the power battery BAT is directly charged in an embodiment of the present invention;

[0051] Figure 4 It is a schematic diagram of the current direction when the upper bridge of the first bridge arm, the second bridge arm, and the third bridge arm are controlled to be closed and the lower bridge is turned on in the boost charging of the power battery BAT in an embodiment of the present invention, and a schematic diagram of the current direction when the upper bridge of the first bridge arm, the second bridge arm, and the third bridge arm are controlled to be closed and the lower bridge is turned on for a second preset time in the boost pre-charging of the pre-charge capacitor X;

[0052] Figure 5 It is a schematic diagram of the current direction when the lower bridge of the first bridge arm, the second bridge arm and the third bridge arm are controlled to be closed and the upper bridge is turned on during the boost charging of the power battery BAT in an embodiment of the present invention;

[0053] Figure 6 Schematic diagram of the current direction when the first switch tube K4 is closed and the second switch tube K5 is disconnected during the step-down charging of the power battery BAT in the embodiment of the present invention;

[0054] Figure 7Schematic diagram of the current direction when the first switch tube K4 is disconnected and the second switch tube K5 is closed during the step-down charging of the power battery BAT in the embodiment of the present invention;

[0055] Figure 8 It is a schematic diagram of the current direction when the lower bridge of the first bridge arm, the second bridge arm and the third bridge arm are controlled to be closed and the upper bridge is turned on during the boost pre-charging of the pre-charge capacitor X in an embodiment of the present invention;

[0056] Fig. 9 Schematic diagram of the current direction when the first switch tube K4 is closed and the second switch tube K5 is disconnected during the step-down pre-charging of the pre-charge capacitor X in the embodiment of the present invention;

[0057] Fig.10 Schematic diagram of the current direction when the first switch tube K4 is disconnected and the second switch tube K5 is closed during the step-down pre-charging of the pre-charge capacitor X in the embodiment of the present invention;

[0058] Fig.11 This is a modular schematic diagram of an electric vehicle according to an embodiment of the present invention. DETAILED DESCRIPTION

[0059] In order to make the above-mentioned purposes, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, are only part of the embodiments of the present invention, not all of the embodiments, and are not used to limit the present invention.

[0060] The inventors found that the voltage range of power batteries of different models of electric vehicles is getting wider and wider, and the power required for charging is also uneven. Due to the differences in the output capacity of charging piles from different manufacturers, some high-voltage models cannot be charged at charging piles with low output voltage, or charging piles with high output voltage cannot charge low-voltage electric vehicles at maximum power output.

[0061] The inventor further found that most manufacturers use direct charging, and some manufacturers use boost charging solutions, which are compatible with charging piles with low output voltages. However, very few have step-down charging functions. For charging piles with high output voltages, the output power of high-voltage charging piles is low, and the output cannot be maximized, and low-voltage electric vehicles cannot be charged well.

[0062] After further research, the inventor creatively discovered that the very few system structures that are currently compatible with buck-boost charging cannot switch between buck and boost smoothly. This is because the current flow direction of the circuit loop in its structure is opposite during boost charging and buck charging. Therefore, when switching from boost to buck, or from buck to boost, an energy release process is required, and the switching can only be achieved after the electric energy is released. This not only causes a waste of electric energy, but also leads to an increase in charging costs and a longer charging time, giving users a bad charging experience.

[0063] In view of the above problems, the inventor creatively proposed a charging system and an electric vehicle of the present invention. The technical solution of the present invention is explained and illustrated in detail below.

[0064] The charging system of the present invention includes: a switch tube, an inductive element and a bridge arm module. Figure 1 , showing a schematic diagram of the circuit structure of a charging system according to an embodiment of the present invention. One end of the switch tube is suitable for being electrically connected to the charging port, and the other end is electrically connected to the first end of the inductive element. It should be noted that the charging port is a DC charging port connected to a DC charging pile. Since electric vehicles currently support DC charging, DC charging is generally achieved using a charging pile. The electric energy received by the charging port in the embodiment of the present invention refers to electric energy in the form of DC.

[0065] The inductive element and the bridge arm module can be existing structures of electric vehicles. For example, the inductive element can be a motor winding, and the bridge arm module can be a control loop of the motor. At present, conventional motors of electric vehicles generally include drive motors and refrigeration system motors (generally air-conditioning motors). Regardless of the type of motor, the structure of its motor control loop is basically the same, and is composed of a metal-oxide semiconductor field-effect transistor (MOS) or an insulated gate bipolar transistor (IGBT). Therefore, any motor and its control loop can be reused.

[0066] In the actual charging process, if boost charging is required (that is, the voltage of the electric energy received by the charging port is lower than the voltage of the power battery), that is, the charging system works in the boost charging mode, the switch tube is controlled to be disconnected, and the inductive element and the bridge arm module are used to form a boost charging circuit to increase the voltage of the electric energy received by the charging port to charge the power battery.

[0067] If step-down charging is required (i.e. the voltage of the electric energy received by the charging port is higher than the voltage of the power battery), that is, the charging system works in the step-down charging mode, the working state of the switch tube is controlled first, and a step-down charging circuit is formed using the inductive element and the bridge arm module to reduce the voltage received by the charging port to charge the power battery.

[0068] It is naturally understandable that if it is direct charging (that is, when the voltage of the electric energy received by the charging port is equal to the voltage of the power battery), that is, when the charging system works in direct charging mode, there is no need for boost or buck charging. The first switch tube is controlled to be closed and the second switch tube is disconnected. The electric energy received by the charging port is transmitted to the power battery through the inductive element and the bridge arm module to directly charge the power battery.

[0069] It should be noted that, in general, the power battery also needs to be equipped with a positive switch and a negative switch, which are referred to as positive and negative switches in the embodiment of the present invention. The switch is generally implemented by a normally open contact on a contactor, rather than a switch tube. When charging the power battery, the positive and negative switches need to be closed. When pre-charging the pre-charge capacitor, the positive and negative switches need to be opened.

[0070] Based on the above circuit structure, a preferred switch tube structure includes: a first switch tube and a second switch tube. The first end of the first switch tube is suitable for being electrically connected to the first end of the charging port (i.e., the positive end); the second end of the first switch tube is electrically connected to the first end of the inductive element; the first end of the second switch tube is electrically connected to the first end of the inductive element; the second end of the second switch tube is suitable for being electrically connected to the second end of the charging port (i.e., the negative end).

[0071] Based on the above switch tube structure, there is another connection relationship: the second end of the first switch tube is electrically connected to the first end of the second switch tube, and the electrical connection is electrically connected to the first end of the inductive element. Both of these connection modes are acceptable.

[0072] Considering that the electric energy received by the charging port may have ripples, which may affect the charging efficiency and quality, the charging system also includes: a filter capacitor; one end of the filter capacitor is electrically connected to the first end of the inductive element, and the other end is electrically connected to the negative end of the bridge arm module; the filter capacitor is used to filter the electric energy received by the charging port, thereby eliminating the ripples that may exist in the electric energy and improving the charging efficiency and quality.

[0073] In addition, since the power battery is discharged when driving or in similar working conditions, although the switch tube is disconnected in such working conditions, the power battery will not be transmitted to the charging port, causing the charging port to be charged. If a person accidentally touches the charging port or the corresponding position without knowing it, there will be a risk of electric shock. However, in order to further improve safety, the hardware avoids the situation where the switch tube may be closed due to an error in the control signal or cannot be disconnected when the switch tube is damaged. Therefore, the charging system also includes: a first contactor or a second contactor.

[0074] One end of the first contactor is electrically connected to the second end of the switch tube, and the other end is electrically connected to the first end of the inductive element; the first contactor is used to control the on-off of the circuit between the second end of the switch tube and the first end of the inductive element. The first contactor is used to distinguish between driving and charging conditions in a hardware manner. When driving or in similar working conditions, the first contactor is disconnected to prevent the charging port from being energized when the power battery is discharged. In this way, even if a person accidentally touches the charging port or the corresponding position without knowing it, there will be no risk of electric shock. When the first contactor is closed during charging, since the charging gun has been plugged into the charging port, there is no risk of electric shock.

[0075] If there is only a second contactor, one end of the second contactor is electrically connected to the negative terminal of the bridge arm module, and the other end is suitable for being electrically connected to the second end of the charging port. The second contactor is used to control the on-off of the circuit between the charging port and the negative terminal of the bridge arm module. In this way, since the circuit from the power battery to the negative pole of the charging port can be disconnected by the second contactor, the problem of the charging port being charged when the power battery is discharged is also avoided. Of course, a better way is to set both the first contactor and the second contactor in the circuit, so that safety is doubly guaranteed. In the event that one of the contactors is damaged, it can still be ensured that the charging port is not charged when the power battery is discharged.

[0076] In addition, if there is a filter capacitor, one end of the second contactor is electrically connected to the negative terminal of the bridge arm module and the filter capacitor respectively, and the other end is electrically connected to the negative terminal of the charging port.

[0077] For the two switch tubes, preferably, the first switch tube includes: a first field effect tube; the second switch tube includes: a second field effect tube. The first end of the first field effect tube is suitable for being electrically connected to the positive terminal of the charging port, the third end receives the first control signal, and the second end is electrically connected to the first end of the inductive element; the first end of the second field effect tube is electrically connected to the first end of the inductive element, the third end is suitable for receiving the second control signal, and the second end is electrically connected to the second end of the charging port and the negative terminal of the power battery respectively.

[0078] It is naturally understandable that if the second end of the first field effect tube is electrically connected to the first end of the second field effect tube, then the electrical connection point between the two is electrically connected to the first end of the inductive element.

[0079] The inductive element includes: N-phase windings; the bridge arm module includes: N bridge arms connected in parallel. In order to better illustrate the structure and working process of the inductive element and the bridge arm module, the following takes the motor winding as the inductive element and the motor control circuit as the bridge arm module as an example.

[0080] The windings of a general motor include: a three-phase winding; the motor control circuit includes: a first bridge arm, a second bridge arm, and a third bridge arm; the first ends of each of the three-phase windings are short-circuited and connected to the electrical connection points of the two field effect transistors; the second end of the first winding in the three-phase winding is electrically connected to the midpoint of the first bridge arm, the second end of the second winding is electrically connected to the midpoint of the second bridge arm, and the second end of the third winding is electrically connected to the midpoint of the third bridge arm.

[0081] In order to more clearly explain and illustrate the circuit structure of the above charging system, refer to Figure 2 A schematic diagram of the circuit structure of a preferred charging system is shown. Figure 2 The specific structure of the field effect transistor, three-phase winding, three bridge arms, and pre-charge capacitor X and filter capacitor C are shown as an example. It includes: a positive switch K1 of the power battery, a negative switch K2, a second contactor K3, a first switch tube K4, a second switch tube K5, a first contactor K6, a charging port J, a power battery BAT, a three-phase winding, and three bridge arms WBA.

[0082] During direct charging, the first switch tube K4 is closed, the positive and negative switches K1 and K2 are closed, the second switch tube K5 is disconnected, the second contactor K3 and the first contactor K6 are closed, and the lower bridges of the first bridge arm, the second bridge arm and the third bridge arm are controlled to be closed, and the upper bridge of at least one bridge arm is turned on. Then, the electric energy received by the charging port J is transmitted to the power battery through the three-phase winding and the upper bridge of the first bridge arm, the second bridge arm or the third bridge arm, so as to directly charge the power battery. The specific current direction during charging can be referred to Figure 3 As shown. During direct charging, since the three-phase winding is always energized, and it can be regarded as a three-phase inductor in terms of electrical characteristics, and since the inductor can be regarded as a wire when it is always energized, direct charging can be achieved. It should be noted that in the charging process of any mode, or in the pre-charging process of the pre-charge capacitor, whether the upper bridge of the bridge arm is turned on or the lower bridge is turned on, one bridge arm can be turned on. Of course, two bridge arms can also be turned on or all three bridge arms are turned on. The difference is that the performance is different, such as power, ripple, etc. For example: All three bridge arms are turned on, and their power is higher than that of two bridge arms and one bridge arm, and the efficiency is higher. Of course, when three bridge arms are turned on at the same time, the ripple is larger than when three bridge arms are turned on alternately. These are all known to those skilled in the art based on the structure of the motor and its control circuit, and they will not be repeated one by one.

[0083] When the voltage of the electric energy received at the charging port is lower than the voltage of the power battery, for example, the voltage of the power battery is 600V, but the charging pile can only provide 500V, boost charging is required. During boost charging, the second contactor K3 and the first contactor K6 are closed, the first switch tube K4 is controlled to be closed, the second switch tube K5 is disconnected, and the positive and negative switches K1 and K2 of the power battery are closed, and the upper bridges of the first bridge arm, the second bridge arm, and the third bridge arm are controlled to be closed, and the lower bridge of at least one bridge arm is turned on for the first preset time. Then, the electric energy received at the charging port is used for three-phase winding charging. For the specific current direction during charging in this case, please refer to Figure 4 shown.

[0084] After the first preset time, the lower bridges of the first bridge arm, the second bridge arm, and the third bridge arm are controlled to be closed, and the upper bridge of at least one bridge arm is turned on (which is opposite to the switch state of the bridge arm when charging the three-phase winding). Then, the electric energy received by the charging port J and the three-phase winding freewheeling work together to increase its voltage and charge the power battery, thus achieving boost charging. In this case, the specific current direction during charging can be referred to Figure 5 These two processes are repeated, that is, Figure 4 , Figure 5 The two current charging processes shown are repeated until the charging is completed, for example, until the power battery is fully charged.

[0085] When the voltage of the electric energy received at the charging port is higher than the voltage of the power battery, for example: the voltage of the power battery is 300V, and the charging pile can provide 800V, it is necessary to step down the voltage for charging. During step-down charging, the second contactor K3 and the first contactor K6 are closed, and the positive and negative switches K1 and K2 are directly closed. In the first stage, the first switch tube K4 is controlled to be closed for a period of time, and the second switch tube K5 is disconnected for a period of time, and the lower bridges of the first bridge arm, the second bridge arm, and the third bridge arm are controlled to be closed, and the upper bridge of at least one bridge arm is turned on. Then, the electric energy received by the charging port J is the simultaneous charging of the three-phase winding and the power battery. Since the three-phase winding can be regarded as an inductor in terms of electrical characteristics, and the inductor has the function of hindering the current during charging for a period of time (not always charged), it can be regarded as having a higher resistance value. In this case, it actually receives electric energy together with the power battery voltage divider, so the voltage received by the power battery will become lower, that is, the power battery step-down charging is achieved. In this case, the specific current direction during charging can be referred to. Figure 6 As shown in the figure. Since the output voltage of the charging pile is higher than the power battery voltage, its output power is higher than when it is output at the power battery voltage, which improves the output power of the charging pile and charges low-voltage electric vehicles well, maximizing the power utilization of the charging pile, making the charging pile output as large as possible, and shortening the charging time.

[0086] After the first switch tube K4 is closed for a period of time and the second switch tube K5 is disconnected for a period of time, in the second stage, the first switch tube K4 is controlled to be disconnected for a period of time and the second switch tube K5 is controlled to be closed for a period of time. The two periods of time may be the same or different. The specific period of time is determined by the actual voltage of the power battery. At the beginning of charging, the actual voltage is low, and as the charging process proceeds, the actual voltage will become higher and higher, so the corresponding closing or disconnecting time will also become shorter. The specific time can be determined according to the actual voltage of the power battery.

[0087] After the first switch tube K4 is closed for a period of time and the second switch tube K5 is opened for a period of time, in the second stage, the first switch tube K4 is controlled to be opened and the second switch tube K5 is closed, and then the lower bridges of the first bridge arm, the second bridge arm and the third bridge arm are controlled to be closed and the upper bridge of at least one bridge arm is turned on (the same as the switching state of the bridge arm when the three-phase winding and the power battery are charged at the same time as before), the three-phase winding continues to charge the power battery at a reduced voltage, and the electric energy received by the charging port no longer supplies power to the three-phase winding and the power battery during this period of time. In this case, the specific current direction during charging can be referred to Figure 7 These two processes are repeated, that is, Figure 6 , Figure 7 The two current charging processes shown are repeated until charging is completed.

[0088] Through the above description, combined with Figure 4 , Figure 5 , Figure 6 , Figure 7 It can be seen from the current direction that the charging system proposed by the present invention, whether it is boost charging or buck charging, its current direction is always consistent, and the opposite situation will not occur. For example: when charging an electric car at present, it may send its own real-time voltage of 200V to the charging pile, while the voltage of the power battery when fully charged is 1000V, and the maximum charging voltage that the charging pile can provide is 750V. Then at the beginning, the charging system charges the power battery in a buck charging manner, and the charging pile can maximize the output and have high output power; when the power battery is charged to 750V, the charging system does not need to release electric energy, and directly switches to the boost charging mode to continue charging the power battery smoothly and seamlessly until the power battery is fully charged to 1000V.

[0089] Therefore, no matter it is switching from boost to buck, or from buck to boost, the charging system does not require an energy release process, and does not need to release the electrical energy before switching. It will not cause waste of electrical energy, reduce charging costs, shorten charging time, and bring users a better charging experience.

[0090] For the pre-charge capacitor X, generally before charging the power battery, it is necessary to pre-charge the pre-charge capacitor X first, so that the voltage of the pre-charge capacitor X reaches or is close to the real-time voltage of the power battery. The current timing of the pre-charge capacitor X is similar to that of boost and buck charging.

[0091] When boost pre-charging is required, that is, when the charging system works in boost pre-charging mode, the second contactor K3 and the first contactor K6 are closed, the first switch tube K4 is controlled to be closed, the second switch tube K5 is disconnected, and the positive and negative switches K1 and K2 of the power battery are disconnected, and the upper bridges of the first bridge arm, the second bridge arm, and the third bridge arm are controlled to be closed, and the lower bridge of at least one bridge arm is turned on for the second preset time. Then, the electric energy received by the charging port J or the electric energy provided by the in-vehicle power supply (for example, the high-voltage side of the battery after DC-DC conversion) is used to charge the three-phase winding. In this case, the specific current direction during charging can be referred to Figure 4 As shown, the only difference is that when the pre-charge capacitor X is boosted and pre-charged, the positive and negative switches K1 and K2 are disconnected instead of closed.

[0092] After the second preset time, the lower bridges of the first bridge arm, the second bridge arm, and the third bridge arm are controlled to be closed, and the upper bridge of at least one bridge arm is turned on. Then, the electric energy received by the charging port J or the electric energy provided by the power supply in the vehicle and the three-phase winding freewheeling work together to increase the voltage and charge the pre-charge capacitor X. This process is repeated until the voltage of the pre-charge capacitor X differs from the current real-time voltage of the power battery within the preset range. In this case, the specific current direction during charging can be referred to Figure 8 shown.

[0093] When pre-charging at reduced voltage is required, that is, the charging system works in the pre-charging mode, the second contactor K3 and the first contactor K6 are closed, and the positive and negative switches K1 and K2 are disconnected. In the first stage, the first switch tube K4 is controlled to be closed for a period of time, and the second switch tube K5 is first disconnected for a period of time, and the lower bridges of the first bridge arm, the second bridge arm, and the third bridge arm are controlled to be closed, and the upper bridge of at least one bridge arm is turned on. Then, the electric energy received by the charging port J or the electric energy provided by the power supply in the car is used to charge the three-phase winding and the pre-charging capacitor X at the same time, that is, the pre-charging capacitor X is charged at reduced voltage. In this case, the specific current direction during charging can be referred to Fig. 9 shown.

[0094] After controlling the first switch tube K4 to close for a period of time and the second switch tube K5 to open for a period of time, in the second stage, the first switch tube K4 is opened for a period of time and the second switch tube K5 is closed for a period of time. The situation here is the same as the aforementioned step-down charging. The two time periods may be the same or different. The specific time period is also determined according to the actual voltage of the power battery. During this period, the lower bridges of the first bridge arm, the second bridge arm, and the third bridge arm are controlled to be closed, and the upper bridge of at least one bridge arm is turned on. Then, the three-phase winding continues to step down and charge the pre-charge capacitor X. This process is repeated until the voltage of the pre-charge capacitor X differs from the current real-time voltage of the power battery BAT within a preset range. In this case, the specific current direction during charging can be referred to. Fig.10 shown.

[0095] During direct pre-charging, that is, when the charging system works in the direct pre-charging mode, the second contactor K3 and the first contactor K6 are closed, the first switch tube K4 is controlled to be closed, the second switch tube K5 is disconnected, the positive and negative switches K1 and K2 are disconnected, and the lower bridges of the first bridge arm, the second bridge arm, and the third bridge arm are controlled to be closed, and the upper bridge of at least one bridge arm is turned on. Then, the electric energy received by the charging port J or the electric energy provided by the in-vehicle power supply is input to the pre-charge capacitor X through the three-phase winding and the upper bridge of at least one bridge arm, and the pre-charge capacitor X is directly charged until the voltage of the pre-charge capacitor differs from the current real-time voltage of the power battery BAT within a preset range.

[0096] The above method realizes the pre-charging of the pre-charge capacitor X. In addition, when the charging port J does not receive power or the charging port J fails to transmit power, the pre-charge capacitor X can be pre-charged with the power provided by the power supply in the vehicle, so that when the power battery BAT is subsequently discharged, the pre-charge capacitor X can be pre-charged first and then discharged to the outside, which will not cause a discharge failure of the power battery BAT.

[0097] Based on the above charging system, an embodiment of the present invention further provides an electric vehicle, referring to Fig.11 The modular schematic diagram of an electric vehicle is shown, and the electric vehicle includes: a charging system as described above.

[0098] Through the above embodiments, in the charging system of the present invention, only a switch tube is added, and a DC fast charging boost or buck module is no longer needed, thereby realizing the buck-boost charging function. That is, when boost charging is required, a boost charging circuit is formed by using an inductive element and a bridge arm module, and the voltage received by the charging port is increased to charge the power battery, solving the problem of boosting the low-voltage charging pile to charge the electric vehicle; at the same time, when step-down charging is required, a step-down charging circuit is formed by using an inductive element and a bridge arm module, and the voltage received by the charging port is reduced to charge the power battery, solving the problem that the high-voltage charging pile has low output power and cannot charge low-voltage electric vehicles well, and cannot maximize the use of the charging pile power, so that the charging pile can output as much power as possible and reduce the charging time. Through the above-mentioned boost and step-down methods, the compatibility and convenience of electric vehicle charging are improved.

[0099] In addition, during the charging process, all circuit loops have the participation of inductive elements and switch tubes, which can effectively avoid the risk of short circuit between the vehicle and the charging pile during charging. In addition to the participation of inductance, it can also be combined with the pre-charging circuit of the power battery to further prevent the risk of short circuit between the vehicle and the charging pile.

[0100] The first contactor or the second contactor is in a closed state during boost and buck charging, distinguishing between driving and charging conditions. When driving or in similar conditions, the first contactor or the second contactor is disconnected to prevent the charging port from being charged when the power battery is discharged, thereby preventing people from accidentally touching the charging port or the corresponding position without knowing it, and avoiding the risk of electric shock.

[0101] The entire charging system reuses the original structure with very few additional components. Therefore, the overall structure uses fewer components and the circuit lines are simple, which reduces space occupancy while also reducing the cost of electric vehicles. In addition, the control logic is relatively simple, which indirectly reduces the difficulty of EMC design of the entire vehicle.

[0102] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. 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.

[0103] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or terminal device including the elements.

[0104] The technical solutions provided by the embodiments of the present invention are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A charging system, characterized in that: The charging system comprises: a switch tube, an inductive element and a bridge arm module; One end of the switch tube is suitable for being electrically connected to the charging port, and the other end is electrically connected to the first end of the inductive element; The second end of the inductive element is suitable for being electrically connected to the power battery through the bridge arm module; When the charging system operates in the boost charging mode, the working state of the switch tube is controlled, and the inductive element and the bridge arm module are used to form a boost charging circuit to increase the voltage received by the charging port to charge the power battery; When the charging system operates in the step-down charging mode, the working state of the switch tube is controlled, and the inductive element and the bridge arm module are used to form a step-down charging circuit to charge the power battery after reducing the voltage received by the charging port.

2. The charging system according to claim 1, characterized in that: The switch tube comprises: a first switch tube and a second switch tube; The first end of the first switch tube is suitable for being electrically connected to the first end of the charging port; The second end of the first switch tube is electrically connected to the first end of the inductive element; The first end of the second switch tube is electrically connected to the first end of the inductive element; The second end of the second switch tube is suitable for being electrically connected to the second end of the charging port.

3. The charging system according to claim 2, characterized in that: The second end of the first switch tube is electrically connected to the first end of the second switch tube, and the electrical connection point is electrically connected to the first end of the inductive element.

4. The charging system according to claim 1, characterized in that: When the charging system operates in the direct charging mode, the working state of the switch tube is controlled, and a direct charging loop is formed by using the inductive element and the bridge arm module, and the voltage received by the charging port is used to directly charge the power battery.

5. The charging system according to claim 1, characterized in that: The charging system further comprises: a filter capacitor; One end of the filter capacitor is electrically connected to the first end of the inductive element, and the other end is electrically connected to the negative terminal of the bridge arm module; The filter capacitor is used to filter the electric energy received by the charging port.

6. The charging system according to claim 1, characterized in that: The charging system further includes: a first contactor or a second contactor; One end of the first contactor is electrically connected to the second end of the switch tube, and the other end is electrically connected to the first end of the inductive element; The first contactor is used to control the on / off of the circuit between the second end of the switch tube and the first end of the inductive element; One end of the second contactor is electrically connected to the negative end of the bridge arm module, and the other end is suitable for being electrically connected to the second end of the charging port; The second contactor is used to control the on / off of the circuit between the charging port and the negative terminal of the bridge arm module.

7. The charging system according to claim 2, characterized in that: The first switch tube includes: a first field effect tube; the second switch tube includes: a second field effect tube; The first end of the first field effect tube is suitable for being electrically connected to the first end of the charging port, the third end is suitable for receiving a first control signal, and the second end is electrically connected to the first end of the inductive element; The first end of the second field effect tube is electrically connected to the first end of the inductive element, the third end is suitable for receiving the second control signal, and the second end is electrically connected to the second end of the charging port and the negative terminal of the power battery respectively.

8. The charging system according to claim 2, characterized in that: The inductive element includes: N-phase windings; the bridge arm module includes: N bridge arms connected in parallel; The first end of the N-phase winding is electrically connected to the other end of the switch tube; The second ends of the N-phase windings are connected to the midpoints of the N bridge arms in a one-to-one correspondence, where N is an integer greater than or equal to 1.

9. The charging system according to claim 8, characterized in that: When the charging system operates in the boost charging mode, the first switch tube is controlled to be closed, the second switch tube is controlled to be disconnected, and the upper bridges of the N bridge arms are controlled to be closed, and the lower bridge of at least one bridge arm is controlled to be turned on for a first preset time, so that the electric energy received by the charging port is used to charge the N-phase winding; After the first preset time is turned on, the lower bridges of the N bridge arms are controlled to be closed and the upper bridge of at least one bridge arm is turned on, so that the charging port and the N-phase winding charge the power battery together; The above process is repeated until charging is completed.

10. The charging system according to claim 8, characterized in that: When the charging system operates in the step-down charging mode, in the first stage, the first switch tube is controlled to be closed, the second switch tube is disconnected, and the lower bridges of the N bridge arms are controlled to be closed and the upper bridge of at least one bridge arm is turned on, so that the charging port charges the N-phase winding and the power battery at the same time; In the second stage, the first switch tube is controlled to be disconnected, the second switch tube is controlled to be closed, and the lower bridges of the N bridge arms are controlled to be closed, and the upper bridge of at least one bridge arm is controlled to be turned on, so that the N-phase winding is freewheeling to reduce the voltage and charge the power battery; The above process is repeated until charging is completed.

11. The charging system according to claim 8, characterized in that: When the charging system operates in the direct charging mode, the first switch tube is controlled to be closed and the second switch tube is controlled to be disconnected, and the lower bridges of the N bridge arms are controlled to be closed and the upper bridge of at least one bridge arm is turned on, so that the charging port, the three-phase winding and the upper bridges of the N bridge arms are directly connected to charge the power battery.

12. The charging system according to claim 8, characterized in that: The charging system also includes: a pre-charge capacitor and a positive and negative switch of the power battery; The pre-charge capacitor is electrically connected to the positive terminal and the negative terminal of the power battery; When the charging system operates in the boost pre-charging mode, the first switch tube is controlled to be closed, the second switch tube is controlled to be disconnected, the positive and negative switches are controlled to be disconnected, and the upper bridges of the N bridge arms are controlled to be closed, and the lower bridge of at least one bridge arm is controlled to be turned on for a second preset time, so that the electric energy received by the charging port or the electric energy provided by the in-vehicle power supply is used to charge the three-phase winding; After the second preset time is turned on, the lower bridges of the N bridge arms are controlled to be closed and the upper bridge of at least one bridge arm is turned on, so that the electric energy received by the charging port or the electric energy provided by the in-vehicle power supply and the three-phase winding freewheeling are used to charge the pre-charge capacitor together, and this process is repeated until the voltage of the pre-charge capacitor differs from the current real-time voltage of the power battery within a preset range; When the charging system operates in the buck pre-charging mode, in the first stage, the positive and negative switches are controlled to be disconnected, the first switch tube is closed, the second switch tube is disconnected, and the lower bridges of the N bridge arms are controlled to be closed and the upper bridge of at least one bridge arm is turned on, so that the electric energy received by the charging port or the electric energy provided by the in-vehicle power supply is used to charge the N-phase winding and the pre-charging capacitor at the same time; In the second stage, the positive and negative switches are controlled to be disconnected, the first switch tube is disconnected, the second switch tube is closed, and the lower bridges of the N bridge arms are controlled to be closed and the upper bridge of at least one bridge arm is turned on, so that the N-phase winding continues to charge the pre-charge capacitor by freewheeling, and the process is repeated until the voltage of the pre-charge capacitor differs from the current real-time voltage of the power battery within a preset range; When the charging system operates in the direct pre-charging mode, the first switch tube is controlled to be closed, the second switch tube is disconnected, the positive and negative switches are disconnected, and the lower bridges of the N bridge arms are controlled to be closed and the upper bridge of at least one bridge arm is turned on. Then, the electric energy received by the charging port or the electric energy provided by the in-vehicle power supply is input to the pre-charging capacitor through the N-phase winding and the upper bridge of the at least one bridge arm, and the pre-charging capacitor is directly charged until the voltage of the pre-charging capacitor differs from the current real-time voltage of the power battery within a preset range.

13. An electric vehicle, characterized in that: The electric vehicle comprises a charging system as described in any one of claims 1-12.

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