Charging circuit and boosting method of electric automobile

Abstract

The invention provides a charging circuit and a boosting method of an electric vehicle. The charging circuit comprises a power supply; the first end of the first switch tube is connected with an external charging pile, and the second end is connected with a power supply; the motor rotating coil comprises a first winding, a second winding and a third winding which form a three-phase winding; the motor bridge circuit is connected in parallel to two ends of a power supply and comprises a first phase, a second phase and a third phase which form a three-phase circuit, and each phase in the three-phase circuit comprises two IGBT switches; the first end of the second switch tube is connected with an external charging pile, and the second end is connected with the three-phase winding; when the output voltage of the external charging pile is larger than or equal to the voltage of the power supply, the first switching tube is switched on, and when the output voltage of the external charging pile is smaller than the voltage of the power supply, the second switching tube is switched on, and two IGBT switches corresponding to a second phase in the motor bridge circuit are controlled to be switched on and switched off respectively. Through the method, direct charging can be performed when the voltage of the charging pile is matched, and charging is performed after voltage boosting is performed when the voltage of the charging pile is low.

Description

Technical Field

[0001] The present application relates to the field of electric vehicles, and in particular to a charging circuit and a voltage boosting method for an electric vehicle. Background Art

[0002] With the rapid development of electric vehicles, in order to improve the charging efficiency of electric vehicles and shorten the charging time, the voltage platform of some electric vehicles has been increased from 400V to 800V, so that electric vehicles can be quickly charged through a higher voltage platform to expand the application scope of electric vehicles.

[0003] Since the current charging piles are mainly divided into three types according to the maximum output voltage, namely 500V, 750V and 1000V, when the voltage platform of the electric vehicle is 800V, the maximum output voltage of the charging pile may be lower than the battery of the electric vehicle. In this case, the electric vehicle cannot be fast charged normally and needs to be boosted before charging the battery. In other words, it is necessary to develop a circuit that can directly charge when the charging pile voltage matches and can boost the voltage when the charging pile voltage is lower. Summary of the invention

[0004] The embodiments of the present application provide a charging circuit and a voltage boosting method for an electric vehicle. The charging circuit can directly charge when the voltage of the charging pile matches, and can first boost the voltage and then charge when the voltage of the charging pile is low.

[0005] In view of this, a first aspect of an embodiment of the present application provides a charging circuit for an electric vehicle, the charging circuit comprising a power supply, a first switch tube, a motor rotating coil, a motor bridge circuit, a second switch tube and a controller:

[0006] The power supply is used to be charged by an external charging pile;

[0007] The first switch tube has a first end connected to the positive electrode of the external charging pile, and a second end connected to the positive electrode of the power supply;

[0008] The motor rotating coil includes a first winding, a second winding and a third winding forming a three-phase winding;

[0009] The motor bridge circuit is connected in parallel to the two ends of the power supply, and includes a first phase, a second phase and a third phase forming a three-phase circuit, wherein each phase of the three-phase circuit includes two insulated gate bipolar transistor IGBT switches;

[0010] The second switch tube has a first end connected to the positive electrode of the external charging pile, and a second end connected to the three-phase winding;

[0011] The controller is used to determine the magnitude of the output voltage of the external charging pile and the voltage of the power supply. When the output voltage of the external charging pile is greater than or equal to the voltage of the power supply, the first switch tube is turned on. When the output voltage of the external charging pile is less than the voltage of the power supply, the second switch tube is turned on and the second corresponding two IGBT switches in the motor bridge circuit are controlled to open and close respectively, so that the second winding in the motor rotating coil can boost the current of the external charging pile.

[0012] A second aspect of an embodiment of the present application provides a voltage boosting method based on a charging circuit, the method comprising:

[0013] The controller determines the magnitude of the output voltage of the external charging pile and the voltage of the power supply;

[0014] If the output voltage of the external charging pile is greater than or equal to the voltage of the power supply, the controller turns on the first switch tube so that the external charging pile directly charges the power supply;

[0015] If the output voltage of the external charging pile is lower than the voltage of the power supply, the controller turns on the second switch tube and controls the second corresponding two IGBT switches in the motor bridge circuit to open and close respectively, so that the second winding in the motor rotating coil boosts the low-voltage DC power of the external charging pile and charges the power supply.

[0016] The embodiment of the present application provides a charging circuit and a boost method for an electric vehicle, wherein the charging circuit includes a power supply, a first switch tube, a motor rotating coil, a motor bridge circuit, a second switch tube and a controller: the power supply is used to be charged by an external charging pile; the first switch tube, the first end of which is connected to the positive pole of the external charging pile, and the second end of which is connected to the positive pole of the power supply; the motor rotating coil includes a first winding, a second winding and a third winding forming a three-phase winding; the motor bridge circuit is connected in parallel to both ends of the power supply, including a first phase, a second phase and a third phase forming a three-phase circuit, wherein each phase of the three-phase circuit includes The controller comprises two insulated gate bipolar transistor IGBT switches; the second switch tube, the first end is connected to the positive electrode of the external charging pile, and the second end is connected to the three-phase winding; the controller is used to judge the size of the output voltage of the external charging pile and the voltage of the power supply. When the output voltage of the external charging pile is greater than or equal to the voltage of the power supply, the first switch tube is turned on. When the output voltage of the external charging pile is less than the voltage of the power supply, the second switch tube is turned on and the second corresponding two IGBT switches in the motor bridge circuit are controlled to open and close respectively, so that the second winding in the motor rotating coil can boost the current of the external charging pile. Through the above method, it is possible to directly charge by turning on the first switch tube when the charging pile voltage matches, and to boost the voltage first and then charge by turning on the second switch tube when the charging pile voltage is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0018] Figure 1 A circuit diagram of a charging circuit for an electric vehicle provided in an embodiment of the present application;

[0019] Figure 2 A schematic diagram of a process for a voltage boosting method provided in an embodiment of the present application;

[0020] Figure 3 A logic flow chart of the power-on process of an electric vehicle in a non-boost mode provided in an embodiment of the present application;

[0021] Figure 4 A logic flow chart of a power-off process of an electric vehicle in a non-boost mode provided in an embodiment of the present application;

[0022] Figure 5 A logic flow chart of the power-on process of an electric vehicle in boost mode provided by an embodiment of the present application;

[0023] Figure 6 A logic flow chart of the power-off process of an electric vehicle in boost mode provided in an embodiment of the present application. DETAILED DESCRIPTION

[0024] In order to enable those skilled in the art to better understand the solution of the present application, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0025] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0026] In order to increase charging power and shorten charging time, the voltage platform of some electric vehicles has been increased from 400V to 800V, but the current charging piles have not yet fully adapted to the 800V voltage platform. The current charging piles are mainly divided into three types according to the maximum output voltage, namely 500V, 750V and 1000V. When the voltage platform of the electric vehicle is 800V, when charging with 500V and 750V charging piles, the maximum output voltage of the charging pile is less than the high-voltage battery voltage of the electric vehicle, and the vehicle cannot be charged normally. At this time, it is necessary to boost the voltage first and then charge the high-voltage battery.

[0027] In view of this, an embodiment of the present application provides a charging circuit and a boosting method for an electric vehicle, wherein the charging circuit can directly charge when the charging pile voltage matches, and can first boost the voltage and then charge when the charging pile voltage is low.

[0028] The following circuit embodiment is used to illustrate the charging circuit of the electric vehicle provided by the present application. Figure 1 , Figure 1 The circuit diagram of the charging circuit of the electric vehicle provided in the embodiment of the present application includes a power supply, a first switch tube K1, a motor rotating coil, a motor bridge circuit, a second switch tube K2 and a controller:

[0029] Power supply, used to be charged by an external charging pile.

[0030] The power source refers to a device installed in an electric vehicle to provide electric energy output for the electric vehicle, such as a battery. When the power of the power source is exhausted, it is necessary to connect an external charging pile to charge it, that is, the power source is installed on the charging circuit, and the external charging pile charges it through the charging circuit.

[0031] It should be noted that the power supply currently installed in electric vehicles is usually between 400V and 1000V. In order to distinguish 12V low-voltage lead-acid batteries, 400V to 800V batteries are high-voltage batteries in the electric vehicle field, such as Figure 1 As shown in the figure, the Energy Storage System (ESS) refers to the power supply of the electric vehicle, and the 800ESS refers to the 800V high-voltage battery of the electric vehicle. Since the power supply usually used in electric vehicles is a high-voltage battery, when the external charging pile does not match, it needs to be boosted before charging.

[0032] Since DC charging has a fast charging speed, DC charging piles are currently mainly used for charging. Figure 1 As shown, direct current (DC) refers to direct current, and DC Charge refers to a direct current external charging pile that can charge a high-voltage battery.

[0033] The first switch tube K1 has a first end connected to the external charging pile, and a second end connected to the positive electrode of the power supply.

[0034] like Figure 1 As shown, the first end of the first switch tube K1 is directly connected to the external charging pile, and the second end is directly connected to the positive electrode of the power supply, so that when the first switch tube is turned on, the external charging pile can directly charge the power supply of the electric vehicle.

[0035] The second switch tube K2 has a first end connected to the external charging pile, and a second end connected to the three-phase winding.

[0036] Pull out one phase of the three-phase winding, such as Figure 1 As shown, for example, the first winding is connected to one end of the second switch tube K2, and the other end of the second switch tube K2 is connected to the external charging pile, so that when the second switch tube K2 is turned on, the external charging pile charges the power supply through the motor rotating coil and the motor bridge circuit boost.

[0037] The motor rotating coil includes a first winding Lu, a second winding Lv and a third winding Lw forming a three-phase winding. In this embodiment, when the second switch tube is turned on, only Lv participates in the boosting work.

[0038] like Figure 1 As shown, the motor rotation coil includes a first winding, a second winding and a third winding forming a three-phase winding, that is, Figure 1Lu, Lv, and Lw are shown in the figure. The motor coil is a component of the motor of an electric vehicle. The motor is a device that converts electrical energy into mechanical energy in an electric vehicle. The motor coil can store electrical energy. When the energy gradually increases, the voltage also increases. The boost fast charging relies on this characteristic of the motor coil to achieve the boost function. Lv is divided into two stages in the boost charging process: storing electrical energy and releasing electrical energy. When the second corresponding IGBT switch Q2 in the motor bridge circuit is controlled to be disconnected and the IGBT switch Q5 is closed, the input voltage charges Lv. At this time, Lv is storing electrical energy and the voltage at both ends is constantly rising; when Lv is fully charged, Q2 can be controlled to be closed and Q5 can be disconnected. At this time, the output voltage is equal to the input voltage plus the voltage corresponding to Lv. Lv begins to release electrical energy and the voltage at both ends is constantly decreasing. Then Q2 is controlled to be disconnected and Q5 is closed. The continuous repetition of these two stages is the boost process.

[0039] The motor bridge circuit is connected in parallel to both ends of the power supply, and includes a first phase, a second phase, and a third phase forming a three-phase circuit.

[0040] like Figure 1 As shown, the motor bridge circuit is connected in parallel at both ends of the power supply, and has the first phase, the second phase, and the third phase forming a three-phase circuit, which are the U, V, and W phases commonly understood. Each phase has two corresponding IGBT switches, wherein the first two corresponding IGBT switches are Q1 and Q4, the second two corresponding IGBT switches are Q2 and Q5, and the third two corresponding IGBT switches are Q3 and Q6. In this embodiment, the second corresponding Q2 and Q5 are related to boosting. The motor bridge circuit is a component of the inverter of an electric vehicle. In the related art, the motor bridge circuit is used to regulate the various performances of the entire electric vehicle, that is, to give full play to the high-voltage battery and motor of the electric vehicle. In this application, in addition to realizing the control of the motor, the motor bridge circuit can also use the energy storage function of the motor rotating coil to achieve boosting (as described in the motor rotating coil part above).

[0041] The controller is used to determine the size of the output voltage of the external charging pile and the voltage of the power supply. When the output voltage of the external charging pile is greater than or equal to the voltage of the power supply, the first switch tube is turned on. When the output voltage of the external charging pile is less than the voltage of the power supply, the second switch tube is turned on so that the motor rotation coil and the motor bridge circuit can boost the current of the external charging pile.

[0042] The controller can determine the magnitude of the output voltage of the external charging pile and the voltage of the power supply. During the actual charging process, the controller can obtain the output voltage of the external charging pile by exchanging messages with the external charging pile. When the output voltage of the external charging pile is greater than or equal to the voltage of the power supply, it indicates that the external charging pile can directly charge the power supply and the first switch tube can be turned on. Figure 1 As shown, when the first switch is closed, the external charging pile can charge directly to the power supply. When the output voltage of the external charging pile is lower than the voltage of the power supply, for example, when the maximum output voltage of the external charging pile is 500V and 750V and the voltage of the power supply is 800V, it means that the external charging pile needs to be boosted before charging the power supply, and the second switch can be turned on, such as Figure 1 As shown, the charging circuit formed by the second switch tube, the motor rotating coil and the motor bridge circuit can increase the voltage of the external charging pile to input it into the power supply, thereby charging the power supply.

[0043] In some embodiments, the circuit further includes a first capacitor C1:

[0044] The first capacitor C1 has a first end connected to the first switch tube and the second switch tube, and a second end connected to the negative electrode of the power supply, and is used to stabilize the DC power of the external charging pile and allow the charging pile to identify the connection status with the power supply.

[0045] Since the voltage of the external charging pile usually fluctuates greatly, the voltage can be stabilized by charging and discharging the first capacitor C1; at the same time, since the first capacitor C1 itself has a high voltage, the first capacitor C1 can simulate the high-voltage battery, allowing the external charging pile to recognize that the high-voltage battery is connected.

[0046] In some embodiments, the circuit further includes a second capacitor C2, a third switch tube K3, a fourth switch tube K4, a first resistor R1 and a fifth switch tube K5:

[0047] A second capacitor C2 is connected in parallel to both ends of the power supply;

[0048] A third switch tube K3, a first end of which is connected to the second capacitor C2, and a second end of which is connected to the positive electrode of the power supply;

[0049] A fourth switch tube K4, a first end of which is connected to the second capacitor C2, and a second end of which is connected to the first resistor R1;

[0050] A first resistor R1, a first end of which is connected to the fourth switch tube K4, and a second end of which is connected to the positive electrode of the power supply;

[0051] A fifth switch tube K5, a first end of which is connected to the second capacitor C2, and a second end of which is connected to the negative electrode of the power supply;

[0052] The controller is used to turn on the fourth switch tube K4 to charge the second capacitor C2 before the power supply is charged by the external charging pile, and to turn on the third switch tube K3 and turn off the fourth switch tube K4 when the power supply is charged by the external charging pile.

[0053] like Figure 1As shown, the second capacitor C2 is connected in parallel with the motor bridge circuit at both ends of the power supply, and is used to realize the original motor function control function of the motor bridge circuit; the first end of the third switch tube K3 is connected to the second capacitor C2, and the second end is connected to the positive electrode of the power supply, so that when the controller turns on the third switch tube K3, the second capacitor C2 can be directly connected in parallel with the power supply.

[0054] Before the external charging pile charges the power supply, the second capacitor C2 needs to be pre-charged. In order to ensure a smaller pre-charging current, a fourth switch tube K4 and a first resistor R1 are provided in the charging circuit. The first end of the fourth switch tube K4 is connected to the second capacitor C2, and the second end is connected to the first resistor R1. The first resistor R1 has a first end connected to the fourth switch tube K4, and a second end connected to the positive electrode of the power supply, so that when the controller needs to pre-charge the second capacitor C2, the fourth switch tube K4 can be turned on to allow the power supply to pre-charge the second capacitor C2.

[0055] In order to ensure the safety of the circuit, a fifth switch tube K5 is provided in the charging circuit, a first end of which is connected to the second capacitor C2, and a second end of which is connected to the negative electrode of the power supply.

[0056] In some embodiments, in order to ensure the safety of the circuit, the circuit further includes a sixth switch tube K6:

[0057] The sixth switch tube K6 has a first end connected to the negative electrode of the external charging pile, and a second end connected to the negative electrode of the power supply.

[0058] It can be seen that the embodiment of the present application provides a charging circuit for an electric vehicle, which includes a power supply, a first switch tube, a motor rotating coil, a motor bridge circuit, a second switch tube and a controller: a power supply for being charged by an external charging pile; a first switch tube, a first end of which is connected to the positive pole of the external charging pile, and a second end of which is connected to the positive pole of the power supply; a motor rotating coil, including a first winding, a second winding and a third winding forming a three-phase winding; a motor bridge circuit, connected in parallel at both ends of the power supply, including a first phase, a second phase and a third phase forming a three-phase circuit, wherein each phase of the three-phase circuit includes The controller comprises two insulated gate bipolar transistor IGBT switches; the second switch tube, the first end is connected to the positive electrode of the external charging pile, and the second end is connected to the three-phase winding; the controller is used to judge the size of the output voltage of the external charging pile and the voltage of the power supply. When the output voltage of the external charging pile is greater than or equal to the voltage of the power supply, the first switch tube is turned on. When the output voltage of the external charging pile is less than the voltage of the power supply, the second switch tube is turned on and the second corresponding two IGBT switches in the motor bridge circuit are controlled to open and close respectively, so that the second winding in the motor rotating coil can boost the current of the external charging pile. Through the above method, it is possible to directly charge by turning on the first switch tube when the charging pile voltage matches, and to boost the voltage first and then charge by turning on the second switch tube when the charging pile voltage is low.

[0059] The voltage boosting method based on the above charging circuit provided by the present application is described below with a method embodiment. Figure 2 As shown, Figure 2 A schematic flow chart of a voltage boosting method provided in an embodiment of the present application, the method comprising:

[0060] S201. The controller determines the magnitude of the output voltage of the external charging pile and the voltage of the power supply.

[0061] Since there are many types of voltages for external charging piles at present, in order to be able to directly charge the power supply when the maximum output voltage of the external charging pile is greater than or equal to the voltage of the power supply, and to be able to first boost the voltage of the external charging pile and then charge it when the maximum output voltage of the external charging pile is less than the voltage of the power supply, the present application provides two charging modes, one is a non-boost mode, and the other is a boost mode. The two modes charge the battery in different ways through different related operations, and the basis for switching between the two modes is the size of the output voltage of the external charging pile and the voltage of the power supply.

[0062] S202: If the output voltage of the external charging pile is greater than or equal to the voltage of the power supply, the controller turns on the first switch tube so that the external charging pile can directly charge the power supply.

[0063] When the output voltage of the external charging pile is greater than or equal to the voltage of the power supply, it means that the external charging pile can directly charge the power supply, so the controller can directly turn on the first switch tube K1 to allow the current of the external charging pile to directly flow into the battery to start charging, that is, non-boost mode.

[0064] In some embodiments, in order to ensure circuit safety, the controller in S202 turns on the first switch tube, including:

[0065] The controller obtains an initial voltage value of the first capacitor and an initial voltage value of the second capacitor;

[0066] If the difference between the initial voltage value of the first capacitor and the initial voltage value of the second capacitor is smaller than the preset safety value, the controller turns on the first switch tube.

[0067] Specifically, in order to ensure circuit safety, the controller will turn on the first light-opening tube K1 only when the difference between the initial voltage value of the first capacitor C1 and the initial voltage value of the second capacitor C2 is less than a preset safety value.

[0068] In some embodiments, when the output voltage of the external charging pile is greater than or equal to the voltage of the power supply, that is, in a non-boost mode, after turning on the first switch tube, the method further includes:

[0069] The controller turns on the fourth switch tube and the fifth switch tube so that the power supply pre-charges the first capacitor and the second capacitor;

[0070] The controller collects the voltage value of the first capacitor and the voltage value of the second capacitor;

[0071] If the voltage value of the first capacitor is greater than or equal to the first voltage value, and the voltage value of the second capacitor is greater than or equal to the preset second voltage value, the controller turns on the third switch tube, cuts off the fourth switch tube, turns on the sixth switch tube, and sends a charging signal to the external charging pile.

[0072] Specifically, when the output voltage of the external charging pile is greater than or equal to the voltage of the power supply, the controller can turn on the fourth switch tube K4 and the fifth switch tube K5 first after turning on the first switch tube K1, so that the battery can charge the first capacitor C1 and the second capacitor C2. The controller can collect the voltage values ​​of the first capacitor C1 and the second capacitor C2 and perform corresponding detections. When the voltage value of the first capacitor C1 is greater than or equal to the first voltage value, and the voltage value of the second capacitor C2 is greater than or equal to the preset second voltage value, it means that the pre-charging of the first capacitor C1 and the second capacitor C2 is completed, and the third switch tube K3 can be turned on, the fourth switch tube K4 can be cut off, and the sixth switch tube K6 can be turned on, so that the external charging pile can charge the power supply.

[0073] It should be noted that, when the controller determines that the sixth switch tube K6 is closed, the controller can send a charging signal to the charging pile to inform the external charging pile that the charging circuit is ready.

[0074] Through the above control strategy, after the first capacitor C1 and the second capacitor C2 are pre-charged, the external charging pile can safely charge the battery directly.

[0075] In some embodiments, when in the non-boost mode, the method further comprises:

[0076] When receiving a stop charging signal, the controller sends a stop charging signal to the external charging pile so that the external charging pile stops outputting current;

[0077] The controller collects the current value in the charging circuit;

[0078] If the current value is less than the preset shutdown current, the controller cuts off the first switch tube and the sixth switch tube so that the first capacitor is actively discharged;

[0079] The controller collects the voltage value of the first capacitor;

[0080] If the voltage value of the first capacitor is less than the first preset shutdown voltage, the controller cuts off the third switch tube and the fifth switch tube so that the second capacitor is actively discharged.

[0081] When the electric vehicle is in non-boost mode, if a stop charging signal is received, the controller will send a stop charging signal to the external charging pile so that the external charging pile can stop the current output. For the safety of the electric vehicle, it is necessary to cut off the corresponding switch tube in the circuit when the current value of the charging circuit is small. Therefore, the controller collects the current value in the charging circuit. When the current value is less than the preset shutdown current, it means that the current value is small. The controller can safely cut off the first switch tube K1 and the sixth switch tube K6 so that the first capacitor C1 is actively discharged. The controller can collect the voltage value of the first capacitor C1. If the voltage value of the first capacitor C1 is less than the first preset shutdown voltage, the controller can cut off the third switch tube K3 and the fifth switch tube K5 so that the second capacitor C2 is actively discharged, thereby achieving safe power-off in non-boost mode.

[0082] It should be noted that the preset shutdown current, the first preset shutdown voltage and the second preset shutdown voltage are set for safety considerations. In practical applications, the preset shutdown current may be 5A, and the first preset shutdown voltage may be 60V.

[0083] S203. If the output voltage of the external charging pile is lower than the voltage of the power supply, the controller turns on the second switch tube and controls the second corresponding two IGBT switches in the motor bridge circuit to open and close respectively, so that the second winding in the motor rotating coil boosts the low-voltage DC power of the external charging pile and charges the power supply.

[0084] When the output voltage of the external charging pile is lower than the voltage of the power supply, the controller can turn on the second switch tube K2 so that the current of the external charging pile passes through the motor rotating coil and the motor bridge circuit to boost the low-voltage DC power of the external charging pile and then charge the power supply.

[0085] In some embodiments, the controller turns on the second switch in S203, including:

[0086] The controller obtains an initial voltage value of the first capacitor and an initial voltage value of the second capacitor;

[0087] If the difference between the initial voltage value of the first capacitor and the initial voltage value of the second capacitor is smaller than the preset safety value, the controller turns on the second switch tube.

[0088] Specifically, in order to ensure circuit safety, the controller will turn on the second light-opening diode K2 only when the difference between the initial voltage value of the first capacitor C1 and the initial voltage value of the second capacitor C2 is less than a preset safety value.

[0089] In some embodiments, when the output voltage of the external charging pile is less than the voltage of the power supply, that is, the electric vehicle is in a boost mode, after turning on the second switch tube, the method further includes:

[0090] The controller turns on the fourth switch tube and the fifth switch tube so that the power supply pre-charges the second capacitor;

[0091] The controller collects the voltage value of the second capacitor;

[0092] If the voltage value of the second capacitor is greater than or equal to the preset second voltage value, the controller turns on the third switch tube and cuts off the fourth switch tube;

[0093] The controller pre-charges the first capacitor;

[0094] The controller collects the voltage value of the first capacitor;

[0095] If the voltage value of the first capacitor is greater than the preset first voltage value, the controller turns on the sixth switch tube and sends a charging signal to the external charging pile.

[0096] When the output voltage of the external charging pile is less than the voltage of the power supply, after the controller turns on the second switch tube K2, the controller can turn on the fourth switch tube K4 and the fifth switch tube K5 so that the power supply can pre-charge the second capacitor C2. This step is different from the boost mode in that the charging circuit cannot pre-charge the first capacitor C1 at this time. The controller can correspondingly collect the voltage value of the second capacitor. When the voltage value of the second capacitor C2 is greater than the preset second voltage value, the controller can turn on the third switch tube K3 and cut off the fourth switch tube K4 to achieve the parallel connection of the second capacitor C2 and the power supply. Since the power supply cannot charge the first capacitor C1 through the charging circuit, the controller can pre-charge the first capacitor C1 and collect the voltage value of the first capacitor C1. When the voltage value of the first capacitor C1 is greater than the preset first voltage value, it indicates that the pre-charging of the first capacitor C1 is completed. The controller can turn on the sixth switch tube K6 so that the external charging pile can charge the power supply. The controller maintains the voltage of the first capacitor C1 stable during the charging process.

[0097] It should be noted that, when the controller determines that the pre-charging of the first capacitor C1 is completed, the controller may send a charging signal to the charging pile to inform the external charging pile that the charging circuit is ready.

[0098] In addition, the preset second voltage value is the target voltage for pre-charging the second capacitor C2, which can be set to the voltage value of the power supply, and the preset first voltage value is the target voltage for pre-charging the first capacitor C1. In actual applications, the preset first voltage value can be set to the maximum output voltage of the external charging pile minus 40V and the current voltage of the power supply minus 150V, whichever is smaller.

[0099] In some embodiments, in the boost mode, the method further comprises:

[0100] When receiving a stop charging signal, the controller sends a stop charging signal to the external charging pile so that the external charging pile stops outputting current;

[0101] The controller controls the first capacitor to actively discharge to a voltage less than a preset safety voltage value;

[0102] The controller collects the current value in the charging circuit;

[0103] If the current value is less than the preset shutdown current, the controller cuts off the second switch tube and the sixth switch tube so that the first capacitor is actively discharged;

[0104] The controller collects the voltage value of the first capacitor;

[0105] If the voltage value of the first capacitor is less than the first preset shutdown voltage, the controller cuts off the third switch tube and the fifth switch tube so that the second capacitor is actively discharged.

[0106] When the electric vehicle is in boost mode, if a stop charging signal is received, the controller will send a stop charging signal to the external charging pile so that the external charging pile can stop the current output. In boost mode, the controller will discharge the voltage of the first capacitor C1 to the first preset shutdown voltage, which can be 60V, and then the controller can collect the current value of the charging circuit. When the current value is less than the preset shutdown current, the preset shutdown current can be 5A, and the controller can cut off the second switch tube K2 and the sixth switch tube K6 so that the first capacitor C1 is actively discharged; the controller collects the voltage value of the first capacitor C1; if the voltage value of the first capacitor C1 is less than the first preset shutdown voltage, the controller cuts off the third switch tube K3 and the fifth switch tube K5 so that the second capacitor C2 is actively discharged to achieve safe power-off in boost mode.

[0107] The charging method of the charging circuit provided by the present application is described below by another method embodiment, and the method includes:

[0108] When the external charging pile receives the charging signal, the switch tube of the external charging pile is turned on to charge the power supply;

[0109] When the external charging pile receives a stop charging signal, the switch tube of the external charging pile is cut off to stop charging the power supply.

[0110] Specifically, when the external charging pile receives a charging signal, the switch tube inside the external charging pile can be turned on. There are usually two switch tubes inside the external charging pile. When the charging signal is received, the two switch tubes can be turned on and the corresponding ready-to-charge signal is sent to the electric vehicle, informing the electric vehicle that the external charging pile is ready. Subsequently, current is output to the power supply of the electric vehicle to start charging.

[0111] When the external charging pile receives a stop charging signal, the switch tube of the external charging pile can be cut off to stop charging the power supply.

[0112] In some embodiments, for the safety of the external charging pile, before cutting off the switch tube in the charging pile, the power output stop process can be performed first so that the current of the external charging pile gradually decreases. When the current of the external charging pile is reduced to below the safety current of the charging pile, for example 5A, the switch tube inside the external charging pile is disconnected.

[0113] The above method embodiment will be described below based on the specific power-on process of the electric vehicle in the non-boost mode. Figure 3 , Figure 3 A logic flow chart of the power-on process of an electric vehicle in non-boost mode provided in an embodiment of the present application.

[0114] For electric vehicles, the power-on process includes:

[0115] 1. When the output voltage of the external charging pile is greater than or equal to the voltage of the power supply, it is determined that the electric vehicle is in non-boost mode.

[0116] 2. First close the first switch tube K1, and then close the fourth switch tube K4 and the fifth switch tube K5.

[0117] 3. A power source (high voltage battery) is used to charge the first capacitor C1 and the second capacitor C2.

[0118] 4. The battery management system (BMS) detects that the pre-charging of the first capacitor C1 and the second capacitor C2 is completed.

[0119] 5. Close the third switch tube K3, then open the fourth switch tube K4, and finally close the sixth switch tube K6.

[0120] 6. Send a preparation completion signal to the external charging pile. For example, BRO SPN2829=0xAA can be sent to the external charging pile to inform the external charging pile that the electric vehicle is ready and can start charging.

[0121] For an external charging pile, the power-on process includes:

[0122] 1. After receiving the charging signal sent by the electric vehicle, the external charging pile closes the positive and negative switches of the main circuit inside the external charging pile and sends a corresponding ready-to-charge signal to the electric vehicle. For example, CROSPN2830=0xAA can be sent to the electric vehicle to inform the electric vehicle that the external charging pile is ready.

[0123] 2. After closing the switch inside the external charging pile, current can be output to the electric vehicle to charge the power supply (high-voltage battery) of the electric vehicle.

[0124] The above method embodiment will be described below with reference to the specific power-off process of the electric vehicle in the non-boost mode. Figure 4 , Figure 4 A logic flow chart of the power-off process of an electric vehicle in a non-boost mode provided in an embodiment of the present application.

[0125] For electric vehicles, the power-off process includes:

[0126] 1. The BMS detects a charging stop signal sent by an external charging pile and has sent a charging stop signal itself. For example, the charging stop signal includes a BST charging termination message, and the charging stop signal includes a CST charging termination message.

[0127] 2. The electric vehicle determines whether the current of the charging circuit is reduced to below 5A.

[0128] 3. When the charging current decreases to below 5A, the first switch tube K1 and the sixth switch tube K6 are turned off.

[0129] 4. The power distribution unit (PDU) starts internal active discharge to actively discharge the first capacitor C1 of the charging circuit to 0V.

[0130] 5. BMS controls to disconnect the third switch tube K1 and the fifth switch tube K5.

[0131] 6. The clutch control unit (CCU) actively discharges the second capacitor C2 of the charging circuit to below 60V.

[0132] It should be noted that, in order to ensure safety, the judgment condition for turning off the first switch tube K1 and the sixth switch tube K6 includes not only whether the current is reduced to below 5A, but also whether there is no current for more than 5s.

[0133] For an external charging pile, the power-off process includes:

[0134] 1. The external charging pile first sends a pile charging stop signal to the electric vehicle and detects the charging stop signal sent by the electric vehicle. For example, the charging stop signal includes a BST charging termination message, and the pile charging stop signal includes a CST charging termination message.

[0135] 2. The external charging pile stops the current output to quickly reduce the output current of the external charging pile.

[0136] 3. The external charging pile determines whether the output current of the external charging pile is reduced to below 5A.

[0137] 4. When the output current of the external charging pile decreases to below 5A, disconnect the switch inside the external charging pile.

[0138] It should be noted that in order to ensure safety, the judgment conditions for disconnecting the switch inside the external charging pile include not only whether the current is reduced to below 5A, but also whether there is no current for more than 5s.

[0139] The above method embodiment will be described below based on the specific power-on process of the electric vehicle in the boost mode. Figure 5 , Figure 5 A logic flow chart of the power-on process of an electric vehicle in boost mode provided in an embodiment of the present application.

[0140] For electric vehicles, the power-on process includes:

[0141] 1. When the output voltage of the external charging pile is lower than the voltage of the power supply, it is judged that the electric vehicle adopts the boost mode.

[0142] 2. First close the second switch tube K2, and then close the fourth switch tube K4 and the fifth switch tube K5.

[0143] 3. Power supply to charge the second capacitor C2.

[0144] 4. The BMS detects that the pre-charging of the second capacitor C2 is completed.

[0145] 5. Close the third switch tube K3 and then open the fourth switch tube K4.

[0146] 6. The automotive power electronics box (PEB) charges the first capacitor C1. For example, the BMS sends a precharge instruction BMSReqPEBOfbdMd (0x3 = Precharge ControlMode) to the PEB, and the BMS sends "BMSReqPEBChrgVol" to the PEB. The PEB closes the internal IGBT switch to charge the first capacitor C1 until the precharge of the first capacitor C1 is completed.

[0147] 7. PEB detects the voltage value of the first capacitor C1 and sends it to the BMS, and the BMS can detect whether the first capacitor C1 is fully charged.

[0148] 8. When the voltage value of the first capacitor C1 is fully charged, the BMS can send a charging instruction BMSReqPEBOfbdMd (0x2 = Voltage Control Mode) to the PEB to exit the pre-charge mode so that the PEB can start the boost mode. After the PEB feedbacks PEBOfbdMdSts (0x2 = Voltage Control Mode), the BMS controls the closing of the sixth switch tube K6 and sends a preparation completion signal to the external charging pile. For example, the preparation completion signal includes BRO SPN2829 = 0xAA to inform the charging pile that the electric vehicle is ready.

[0149] For an external charging pile, the power-on process includes:

[0150] 1. After receiving the charging signal sent by the electric vehicle, the external charging pile closes the positive and negative switches of the main circuit inside the external charging pile and sends a corresponding ready-to-charge signal to the electric vehicle. For example, CROSPN2830=0xAA can be sent to the electric vehicle to inform the electric vehicle that the external charging pile is ready.

[0151] 2. After closing the switch inside the external charging pile, current can be output to the electric vehicle to charge the power supply of the electric vehicle.

[0152] The above method embodiment will be described below with reference to the specific power-off process of the electric vehicle in the boost mode. Figure 6 , Figure 6 A logic flow chart of the power-off process of an electric vehicle in boost mode provided in an embodiment of the present application.

[0153] For electric vehicles, the power-off process includes:

[0154] 1. The BMS detects a charging stop signal sent by an external charging pile and has sent a charging stop signal itself. For example, the charging stop signal includes a BST charging termination message, and the charging stop signal includes a CST charging termination message.

[0155] 2. PEB will actively discharge the first capacitor C1 of the charging circuit until the active discharge of the first capacitor C1 is completed.

[0156] 3. The electric vehicle determines whether the current of the charging circuit is reduced to below 5A.

[0157] 4. When the charging current decreases to below 5A, the BMS controls the second switch tube K2 and the sixth switch tube K6 to be disconnected.

[0158] 5. The PDU starts internal active discharge to reduce the voltage of the first capacitor C1 to 0V.

[0159] 6. The BMS controls to turn off the third switch K3 and the fifth switch K5.

[0160] 7. The CCU actively discharges to reduce the voltage of the second capacitor C2 to below 60V.

[0161] It should be noted that, in order to ensure safety, the judgment condition for turning off the first switch tube K1 and the sixth switch tube K6 includes not only whether the current is reduced to below 5A, but also whether there is no current for more than 5s.

[0162] For an external charging pile, the power-off process includes:

[0163] 1. The external charging pile first sends a pile charging stop signal to the electric vehicle and detects the charging stop signal sent by the electric vehicle. For example, the charging stop signal includes a BST charging termination message, and the pile charging stop signal includes a CST charging termination message.

[0164] 2. The external charging pile stops the current output and quickly reduces the output current of the external charging pile.

[0165] 3. The external charging pile determines whether the output current of the external charging pile is reduced to below 5A.

[0166] 4. When the output current of the external charging pile decreases to below 5A, disconnect the switch inside the external charging pile.

[0167] It should be noted that in order to ensure safety, the judgment conditions for disconnecting the switch inside the external charging pile include not only whether the current is reduced to below 5A, but also whether there is no current for more than 5s.

[0168] It should be noted that the BMS, PDU, CCU and PEB in the above specific power-on and power-off processes are all controllers in the aforementioned method embodiments.

[0169] Another embodiment of the present application provides an electronic device, including:

[0170] A memory for storing executable instructions;

[0171] The processor is used to implement the method in the above method embodiment of the embodiment of the present application when executing the executable instructions stored in the memory.

[0172] Another embodiment of the present application provides a computer-readable storage medium storing executable instructions for implementing the method in the above method embodiment of the present application when executed by a processor.

[0173] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0174] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A charging circuit for an electric vehicle, characterized in that: The circuit includes a power supply, a first switch tube, a motor rotation coil, a motor bridge circuit, a second switch tube and a controller: The power supply is used to be charged by an external charging pile; The first switch tube has a first end connected to the positive electrode of the external charging pile, and a second end connected to the positive electrode of the power supply; the motor rotation coil includes a first winding, a second winding and a third winding forming a three-phase winding; The motor bridge circuit is connected in parallel to the two ends of the power supply, and includes a first phase, a second phase and a third phase forming a three-phase circuit, wherein each phase of the three-phase circuit includes two insulated gate bipolar transistor IGBT switches; The second switch tube has a first end connected to the positive electrode of the external charging pile, and a second end connected to the three-phase winding; The controller is used to determine the magnitude of the output voltage of the external charging pile and the voltage of the power supply. When the output voltage of the external charging pile is greater than or equal to the voltage of the power supply, the first switch tube is turned on. When the output voltage of the external charging pile is less than the voltage of the power supply, the second switch tube is turned on and the second corresponding two IGBT switches in the motor bridge circuit are controlled to open and close respectively, so that the second winding in the motor rotating coil can boost the current of the external charging pile.

2. The circuit according to claim 1, characterized in that The circuit further includes a first capacitor: The first capacitor has a first end connected to the first switch tube and the second switch tube, and a second end connected to the negative electrode of the power supply, and is used to stabilize the direct current of the external charging pile and allow the charging pile to identify the connection status with the power supply.

3. The circuit according to claim 1, characterized in that: The circuit further includes a second capacitor, a third switch tube, a fourth switch tube, a first resistor and a fifth switch tube: The second capacitor is connected in parallel to both ends of the power supply; The third switch tube has a first end connected to the second capacitor and a second end connected to the positive electrode of the power supply; The fourth switch tube has a first end connected to the second capacitor and a second end connected to the first resistor; The first resistor has a first end connected to the fourth switch tube, and a second end connected to the positive electrode of the power supply; The fifth switch tube has a first end connected to the second capacitor and a second end connected to the negative electrode of the power supply; The controller is used to turn on the fourth switch tube to charge the second capacitor before the power supply is charged by the external charging pile, and to turn on the third switch tube and turn off the fourth switch tube when the power supply is charged by the external charging pile.

4. The circuit according to claim 1, characterized in that The circuit further includes a sixth switch tube: The sixth switch tube has a first end connected to the negative electrode of the external charging pile, and a second end connected to the negative electrode of the power supply.

5. A voltage boosting method based on the charging circuit according to any one of claims 1 to 4, characterized in that: The method comprises: The controller determines the magnitude of the output voltage of the external charging pile and the voltage of the power supply; If the output voltage of the external charging pile is greater than or equal to the voltage of the power supply, the controller turns on the first switch tube so that the external charging pile directly charges the power supply; If the output voltage of the external charging pile is lower than the voltage of the power supply, the controller turns on the second switch tube and controls the second corresponding two IGBT switches in the motor bridge circuit to open and close respectively, so that the second winding in the motor rotating coil boosts the low-voltage DC power of the external charging pile and charges the power supply.

6. The method according to claim 5, characterized in that The controller turns on the first switch tube, comprising: The controller obtains an initial voltage value of the first capacitor and an initial voltage value of the second capacitor; If the difference between the initial voltage value of the first capacitor and the initial voltage value of the second capacitor is smaller than a preset safety value, the controller turns on the first switch tube.

7. The method according to claim 6, characterized in that After turning on the first switch tube, the method further includes: The controller turns on the fourth switch tube and the fifth switch tube so that the power supply pre-charges the first capacitor and the second capacitor; The controller collects a voltage value of the first capacitor and a voltage value of the second capacitor; If the voltage value of the first capacitor is greater than or equal to a preset first voltage value, and the voltage value of the second capacitor is greater than or equal to a preset second voltage value, the controller turns on the third switch tube, cuts off the fourth switch tube, turns on the sixth switch tube, and sends a charging signal to the external charging pile.

8. The method according to claim 7, further comprising: When receiving a stop charging signal, the controller sends the stop charging signal to the external charging pile so that the external charging pile stops outputting current; The controller collects the current value in the charging circuit; If the current value is less than a preset shutdown current, the controller cuts off the first switch tube and the sixth switch tube so that the first capacitor is actively discharged; The controller collects a voltage value of the first capacitor; If the voltage value of the first capacitor is less than a first preset shutdown voltage, the controller cuts off the third switch tube and the fifth switch tube so that the second capacitor is actively discharged.

9. The method according to claim 5, characterized in that The controller turns on the second switch tube, comprising: The controller obtains an initial voltage value of the first capacitor and an initial voltage value of the second capacitor; If the difference between the initial voltage value of the first capacitor and the initial voltage value of the second capacitor is smaller than a preset safety value, the controller turns on the second switch tube.

10. The method according to claim 9, characterized in that After turning on the second switch tube, the method further includes: The controller turns on the fourth switch tube and the fifth switch tube so that the power supply pre-charges the second capacitor; The controller collects a voltage value of the second capacitor; If the voltage value of the second capacitor is greater than or equal to a preset second voltage value, the controller turns on the third switch tube and cuts off the fourth switch tube; The controller pre-charges the first capacitor; The controller collects a voltage value of the first capacitor; If the voltage value of the first capacitor is greater than a preset first voltage value, the controller turns on the sixth switch tube and sends a charging signal to the external charging pile.

11. The method according to claim 10, characterized in that The method further comprises: When receiving a stop charging signal, the controller sends the stop charging signal to the external charging pile so that the external charging pile stops outputting current; The controller controls the first capacitor to actively discharge to a voltage less than a preset safety voltage value; The controller collects the current value in the charging circuit; If the current value is less than a preset shutdown current, the controller cuts off the second switch tube and the sixth switch tube so that the first capacitor is actively discharged; The controller collects a voltage value of the first capacitor; If the voltage value of the first capacitor is less than a first preset shutdown voltage, the controller cuts off the third switch tube and the fifth switch tube so that the second capacitor is actively discharged.

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