A vehicle charging system and method

Abstract

This invention provides a vehicle charging system and method, relating to the field of vehicle charging technology. The system includes: a boost control circuit whose input terminal is connected to a charging pile, and whose output terminal is connected to the input terminal of a power battery and a drive motor; the boost control circuit includes: a voltage detection module and a first switching unit; the input terminal of the voltage detection module is connected to the charging pile, and its output terminal is connected to the first switching unit, the voltage detection module being used to detect the output voltage of the charging pile and the voltage across the first switching unit; a motor controller is connected to the power battery and the drive motor; the power battery includes: a battery module and a switching module connected in parallel with the battery module, the battery module being connected to the charging pile through the boost control circuit; the switching module includes: a second switching unit and a third switching unit, the second switching unit being disposed between the positive terminal of the battery module and the boost control circuit, and the third switching unit being disposed between the negative terminal of the battery module and the boost control circuit.

Description

Technical Field

[0001] This invention relates to the field of vehicle charging technology, and in particular to a vehicle charging system and method. Background Technology

[0002] With the rapid development of the pure electric vehicle industry, the requirements for vehicle power performance are getting higher and higher. In order to meet the increasing requirements for vehicle acceleration, top speed and other performance aspects, under the premise of strictly controlling the cost of vehicle drive system, most pure electric vehicle manufacturers generally improve the performance of vehicle drive system by increasing the output voltage of power battery.

[0003] For the high-output voltage power batteries of pure electric vehicles, a high-voltage DC power supply is required from the outside during the fast charging process. However, due to the lag in the construction of DC fast charging pile infrastructure, most charging piles are not high-voltage DC charging piles. This results in the inability to fast charge vehicles equipped with high-voltage power batteries due to the lack of infrastructure such as charging piles. Summary of the Invention

[0004] This invention provides a vehicle charging system and method to solve the problem in the prior art that high-voltage fast charging of vehicles equipped with high-voltage power batteries is impossible due to infrastructure such as charging piles.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A vehicle charging system, comprising:

[0007] Boost control circuit, motor controller, drive motor, and power battery;

[0008] The input terminal of the boost control circuit is connected to the charging pile, and the output terminal is connected to the input terminal of the power battery and the drive motor. The boost control circuit includes a voltage detection module and a first switching unit. The input terminal of the voltage detection module is connected to the charging pile, and the output terminal is connected to the first switching unit. The voltage detection module is used to detect the output voltage of the charging pile and the voltage across the first switching unit.

[0009] The motor controller is connected to the power battery and the drive motor;

[0010] The power battery includes: a battery module and a switching module connected in parallel with the battery module; the battery module is connected to the charging pile through the boost control circuit.

[0011] The switching module includes a second switching unit and a third switching unit. The second switching unit is disposed between the positive terminal of the battery module and the boost control circuit, and the third switching unit is disposed between the negative terminal of the battery module and the boost control circuit.

[0012] When the output voltage of the charging pile is higher than the preset voltage, the first switch unit is in the open state, and the second switch unit and the third switch unit are in the closed state; when the output voltage of the charging pile is higher than the preset voltage, the first switch unit and the second switch unit are in the closed state, and the third switch unit is in the open state.

[0013] Furthermore, the voltage detection module includes:

[0014] The system comprises a first voltage detection unit, a second voltage detection unit, and a third voltage detection unit.

[0015] The first voltage detection unit is connected to the charging pile and is used to detect the output voltage of the charging pile and transmit the output voltage to the boost control circuit and the motor controller.

[0016] The second voltage detection unit is connected to the first switching unit and is used to detect the voltage across the first switching unit;

[0017] One end of the third voltage detection unit is connected to the charging pile, and the other end is connected to the first switch unit, which is used to detect faults in the first switch unit.

[0018] Furthermore, the boost control circuit also includes:

[0019] Voltage regulator module and discharge module;

[0020] The voltage regulator module is connected to the charging pile and is used to adjust the output voltage of the boost control circuit;

[0021] The discharge module is connected in parallel with the voltage regulator module and is used to consume the power stored in the voltage regulator module after charging is completed.

[0022] Furthermore, the power battery also includes:

[0023] The system includes a fourth switching unit, a fifth switching unit, a pre-charge module, and a monitoring module.

[0024] The first switching unit is the main positive switching unit of the power battery, and the fifth switching unit is the main negative switching unit of the power battery;

[0025] The pre-charge module is connected in parallel with the fifth switch unit;

[0026] The monitoring module is connected in parallel with the battery module, and the monitoring module includes a first voltage detection unit and an insulation monitoring unit connected in series.

[0027] The voltage detection unit is used to detect the voltage across the battery module, and the insulation monitoring unit is used for insulation monitoring of the power battery.

[0028] This invention also provides a vehicle charging method, applied to the vehicle charging system described above, comprising:

[0029] Obtain the output voltage of the charging station;

[0030] When the output voltage is higher than the preset voltage, the first switching unit is controlled to open, and the second and third switching units are controlled to close.

[0031] When the output voltage is lower than the preset voltage, the first and second switching units are controlled to close, and the third switching unit is opened.

[0032] Further, obtaining the output voltage of the charging pile includes:

[0033] The output voltage of the charging pile is obtained through the first voltage detection unit of the voltage detection module, and the output voltage is transmitted to the boost control circuit and the motor controller;

[0034] The voltage across the first switching unit is obtained through the second voltage detection unit of the voltage detection module;

[0035] The output voltage of the boost control circuit is obtained through the third voltage detection unit of the voltage detection module.

[0036] This invention also provides a vehicle charging method, applied to the vehicle charging system described above, comprising:

[0037] When the output voltage of the charging pile is lower than the preset voltage, the voltage value of the DC bus of the motor controller is obtained.

[0038] Based on the voltage value, determine the voltage ripple coefficient of the DC bus of the motor controller;

[0039] The output voltage of the motor controller is linearly controlled in a closed loop based on the voltage ripple coefficient.

[0040] Furthermore, the linear closed-loop control includes voltage closed-loop control, which includes:

[0041] Determine the target voltage, and determine the first voltage difference based on the voltage value;

[0042] Determine the initial current value, the proportional coefficient of the voltage closed-loop control, the integral coefficient of the voltage closed-loop control, and the pulse width modulation period;

[0043] Based on the initial current value, the proportional coefficient of the voltage closed-loop control, the integral coefficient of the voltage closed-loop control, and the pulse width modulation period, voltage closed-loop control is applied to the first voltage difference to obtain the target current value.

[0044] Wherein, the proportional coefficient and the integral coefficient of the voltage closed-loop control are both greater than zero;

[0045] The pulse width modulation period is the output of voltage ripple control.

[0046] Furthermore, the linear closed-loop control includes current closed-loop control, which includes:

[0047] Obtain the current of the motor controller, and determine the first current difference based on the target current value;

[0048] Determine the initial duty cycle of the target upper bridge arm of the motor controller, the proportional coefficient of the current closed-loop control, the integral coefficient of the current closed-loop control, and the pulse width modulation period.

[0049] Based on the initial duty cycle, the proportional coefficient of the current closed-loop control, the integral coefficient of the current closed-loop control, and the pulse width modulation period, the first current difference is subjected to current closed-loop control to obtain the target duty cycle of the target upper bridge arm.

[0050] Wherein, the proportional coefficient and the integral coefficient of the current closed-loop control are both greater than zero.

[0051] Furthermore, the linear closed-loop control includes voltage ripple closed-loop control, which includes:

[0052] Determine the target voltage ripple coefficient, and determine the first ripple coefficient difference based on the voltage ripple coefficient;

[0053] When the difference in the first ripple coefficient is greater than zero, the initial pulse width modulation period, the proportional coefficient of the voltage ripple closed-loop control, and the integral coefficient of the voltage ripple closed-loop control are determined.

[0054] Based on the initial pulse width modulation period, the proportional coefficient of the voltage ripple closed-loop control, and the integral coefficient of the voltage ripple closed-loop control, the first ripple coefficient difference is used as input for voltage ripple closed-loop control to obtain the target pulse width modulation period.

[0055] The proportional coefficient and integral coefficient of the voltage ripple closed-loop control are both greater than zero.

[0056] The beneficial effects of this invention are:

[0057] The vehicle charging system of this invention, by incorporating a motor controller, a drive motor, and a boost control circuit including a voltage detection module and a first switching unit, can adjust the voltage provided by the power battery according to the output voltage of the charging pile. When the output voltage of the charging pile is lower than a preset value, the system increases the output voltage of the charging pile, thereby providing the power battery with a voltage capable of high-voltage charging. This vehicle charging system solves the problem in the prior art where high-voltage fast charging of vehicles equipped with high-voltage power batteries is impossible due to infrastructure limitations such as charging piles. Attached Figure Description

[0058] Figure 1 One of the structural schematic diagrams of a vehicle charging system according to an embodiment of the present invention;

[0059] Figure 2 A second schematic diagram illustrating the structure of a vehicle charging system according to an embodiment of the present invention;

[0060] Figure 3 The third schematic diagram illustrating the structure of the vehicle charging system according to an embodiment of the present invention;

[0061] Figure 4 Fourth schematic diagram illustrating the structure of a vehicle charging system according to an embodiment of the present invention;

[0062] Figure 5 One of the simplified U-phase structural diagrams of the drive motor according to an embodiment of the present invention;

[0063] Figure 6 A second simplified schematic diagram of the U-phase structure of the drive motor according to an embodiment of the present invention;

[0064] Figure 7 The third simplified U-phase structural diagram of the drive motor according to an embodiment of the present invention;

[0065] Figure 8 One of the schematic diagrams illustrating the steps of a vehicle charging method according to an embodiment of the present invention;

[0066] Figure 9 A second schematic diagram illustrating the steps of a vehicle charging method according to an embodiment of the present invention;

[0067] Figure 10 This is a schematic diagram illustrating the PI control architecture of an embodiment of the present invention. Detailed Implementation

[0068] To make the technical problems, technical solutions, and advantages of this invention clearer, a detailed description will be provided below in conjunction with the accompanying drawings and specific embodiments. In the following description, specific details such as particular configurations and components are provided merely to aid in a comprehensive understanding of the embodiments of this invention. Therefore, those skilled in the art should understand that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of this invention. Furthermore, for clarity and brevity, descriptions of known functions and structures have been omitted.

[0069] It should be understood that the phrase "one embodiment" or "an embodiment" throughout the specification means that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of the invention. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification do not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments.

[0070] This invention addresses the problem in the prior art that high-voltage fast charging of vehicles equipped with high-voltage power batteries is impossible due to the lack of infrastructure such as charging piles, and provides a vehicle charging system and method.

[0071] like Figure 1 As shown, an embodiment of the present invention provides a vehicle charging system, including:

[0072] Boost control circuit, motor controller, drive motor, and power battery;

[0073] The input terminal of the boost control circuit is connected to the charging pile, and the output terminal is connected to the input terminal of the power battery. The boost control circuit includes a voltage detection module and a first switching unit S6. The input terminal of the voltage detection module is connected to the charging pile, and the output terminal is connected to the first switching unit S6. The voltage detection module is used to detect the output voltage of the charging pile and the voltage across the first switching unit S6.

[0074] The motor controller is connected to the power battery;

[0075] The power battery includes: a battery module B1 and a switching module connected in parallel with the battery module B1. The battery module B1 is connected to the charging pile through the boost control circuit.

[0076] The switching module includes a second switching unit S4 and a third switching unit S5. The second switching unit S4 is disposed between the positive terminal of the battery module B1 and the boost control circuit, and the third switching unit S5 is disposed between the negative terminal of the battery module B1 and the boost control circuit.

[0077] When the output voltage of the charging pile is higher than the preset voltage, the first switch unit S6 is in the open state, and the second switch unit S4 and the third switch unit S5 are in the closed state; when the output voltage of the charging pile is higher than the preset voltage, the first switch unit S6 and the second switch unit S4 are in the closed state, and the third switch unit S5 is in the open state.

[0078] Optionally, the first switching unit, the second switching unit, and the third switching unit are all relays.

[0079] In one embodiment of the present invention, when the output voltage of the charging pile is greater than a preset value (i.e., the charging pile is a high-voltage charging pile), the boost control circuit is not required to perform boost charging of the power battery; in this case, such as Figure 2 As shown, when the first switch unit is opened and the second and third switch units are closed, the boost control circuit is internally short-circuited, and the positive and negative terminals of the charging pile are directly connected to the power battery to perform high-voltage fast charging of the power battery.

[0080] In one embodiment of the present invention, when the output voltage of the charging pile is less than a preset value (i.e., the charging pile is not a high-voltage charging pile), the boost control circuit is required to perform boost charging on the power battery; at this time, if Figure 3 As shown, the first and second switch units are closed, and the third switch unit is opened; the boost control circuit then uses its negative terminal as a connector.

[0081] It should be noted that when the output voltage of the charging pile is less than the preset value, the third switch unit is in the closed state, and the channel between the power battery and the negative terminal of the charging pile will be meaningless.

[0082] The positive terminal of the charging pile is connected to the positive terminal of the power battery and the positive terminal of the motor controller, forming an equipotential connection. The negative terminal of the charging pile is connected to the neutral point of the drive motor, and is connected to the negative terminal of the power battery via the stator winding coil of the drive motor and the power conversion module (e.g., insulated gate bipolar transistor, IGBT) of the motor controller.

[0083] like Figure 4 As shown, the motor controller and the drive motor form a Boost circuit to increase the voltage difference between the positive and negative terminals of the power battery. By increasing the output voltage of the charging pile, the power battery of the vehicle can be fast-charged.

[0084] In an optional embodiment of the present invention, such as Figure 5As shown, taking the U-phase of the drive motor as an example, the upper and lower bridge arms of the power module of the U-phase are simplified according to their functions. For example, the upper bridge arm of the U-phase is simplified to a switch K, and the lower bridge arm of the U-phase is simplified to a freewheeling diode VD1.

[0085] It should be noted that, according to Figure 5 During the Boost fast charging control process, the upper bridge arm of phase U is turned on (corresponding to switch K being closed). At this time, the current output from the positive terminal of the charging pile flows back to the negative terminal of the charging pile through the winding coil of the drive motor. Figure 6 The current i1 in the inductor (energy stored in the inductor);

[0086] When the upper bridge arm of phase U is disconnected (corresponding switch K is disconnected), a current i2 is generated through the freewheeling diode VD1 of the lower bridge arm of phase U under the action of the winding inductance of the drive motor. Figure 7 As shown, the presence of this current causes the potential at the negative terminal of capacitor C1 to be pulled low;

[0087] according to Figure 5 , 6 In step 7, the positive terminal of the charging pile is at the same potential as the positive terminal of the power battery, and the negative terminal of the power battery is at the same potential as the negative terminal of capacitor C1. This enables the voltage between the positive and negative terminals of the power battery to be increased, thereby achieving the function of boost charging.

[0088] The vehicle charging system of this invention, by incorporating a motor controller, a drive motor, and a boost control circuit including a voltage detection module and a first switching unit, can adjust the voltage provided by the power battery according to the output voltage of the charging pile. When the output voltage of the charging pile is lower than a preset value, the system increases the output voltage of the charging pile, thereby providing the power battery with a voltage capable of high-voltage charging. This vehicle charging system solves the problem in the prior art where high-voltage fast charging of vehicles equipped with high-voltage power batteries is impossible due to infrastructure limitations such as charging piles.

[0089] Optionally, the voltage detection module includes:

[0090] The first voltage detection unit V5, the second voltage detection unit V6, and the third voltage detection unit V7;

[0091] The first voltage detection unit V5 is connected to the charging pile and is used to detect the output voltage of the charging pile and transmit the output voltage to the boost control circuit and the motor controller.

[0092] The second voltage detection unit V6 is connected to the first switching unit S6 and is used to detect the voltage across the first switching unit S6.

[0093] One end of the third voltage detection unit V7 is connected to the charging pile, and the other end is connected to the first switch unit S6, for fault detection of the first switch unit S6.

[0094] Optionally, the first voltage detection unit, the second voltage detection unit, and the third voltage detection unit are all voltage detection meters.

[0095] The vehicle charging system of this invention detects the output voltage of the charging pile through the first voltage detection unit, so that the vehicle charging system can control the closing state of the first switch unit, the second switch unit and the third switch unit according to the output voltage.

[0096] The vehicle charging system of this invention detects adhesion faults in the first switching unit through the third voltage detection unit.

[0097] Optionally, the boost control circuit further includes:

[0098] Voltage regulator module and discharge module;

[0099] The voltage regulator module is connected to the charging pile and is used to adjust the output voltage of the boost control circuit;

[0100] The discharge module is connected in parallel with the voltage regulator module and is used to consume the power stored in the voltage regulator module after charging is completed.

[0101] Optionally, the voltage regulator module is capacitor C2.

[0102] The solution of this embodiment of the invention is used to filter the output voltage of the charging pile, thereby stabilizing the output voltage of the fast charging pile during the fast charging boost control process;

[0103] Optionally, the discharge module includes:

[0104] The switch K1 and the discharge resistor R3 are connected in series.

[0105] In one embodiment of the present invention, K1 is in the open state during the boost control process of the charging system; after the boost control is completed, the charge stored in capacitor C2 needs to be discharged. At this time, switch K1 is closed. In this state, the charge stored in capacitor C2 will be consumed as heat through discharge resistor R3, thereby ensuring the high voltage safety of the system.

[0106] Optionally, the power battery may further include:

[0107] The fourth switch unit S2, the fifth switch unit S1, the precharge module 42, and the monitoring module 43;

[0108] The first switching unit S6 is the main positive switching unit of the power battery, and the fifth switching unit S1 is the main negative switching unit of the power battery;

[0109] The pre-charge module 42 is connected in parallel with the fifth switch unit S1;

[0110] The monitoring module 43 is connected in parallel with the battery module B1. The monitoring module 43 includes a first voltage detection unit V1 and an insulation monitoring unit I1 connected in series.

[0111] The voltage detection unit V1 is used to detect the voltage across the battery module B1, and the insulation monitoring unit I1 is used for insulation monitoring of the power battery.

[0112] Optionally, both the main positive switch unit and the main negative switch unit are relays, and the insulation monitoring unit is a current meter.

[0113] Optionally, the pre-charge module includes a pre-charge group R1 and a pre-charge relay S3 connected in series;

[0114] In one embodiment of the present invention, V1 detects the voltage across the battery module, V2 detects the output voltage of the power battery during pre-charging, and V3 detects the output voltage of the power battery after the pre-charging of the charging system is completed; I1 represents an insulation monitoring circuit, which is used to realize insulation monitoring of the power battery system.

[0115] like Figure 8 As shown. This invention provides a vehicle charging method, applied to the vehicle charging system described above, comprising the following steps:

[0116] Step 801: Obtain the output voltage of the charging pile;

[0117] Step 802: When the output voltage is higher than the preset voltage, control the first switching unit to open, and the second switching unit and the third switching unit to close.

[0118] When the output voltage is lower than the preset voltage, the first and second switching units are controlled to close, and the third switching unit is opened.

[0119] Optionally, obtaining the output voltage of the charging pile includes:

[0120] The output voltage of the charging pile is obtained through the first voltage detection unit of the voltage detection module, and the output voltage is transmitted to the boost control circuit and the motor controller;

[0121] The voltage across the first switching unit is obtained through the second voltage detection unit of the voltage detection module;

[0122] The output voltage of the boost control circuit is obtained through the third voltage detection unit of the voltage detection module.

[0123] like Figure 9 As shown, this embodiment of the invention also provides a vehicle charging method, applied to the vehicle charging system described above, comprising:

[0124] Step 901: If the output voltage of the charging pile is lower than the preset voltage, obtain the voltage value of the DC bus of the motor controller;

[0125] Step 902: Determine the voltage ripple coefficient of the DC bus of the motor controller based on the voltage value;

[0126] Step 903: Perform linear closed-loop control on the output voltage of the motor controller based on the voltage ripple coefficient.

[0127] The vehicle charging method of this invention adopts interleaved parallel technology, and uses the power conversion module of the motor controller and the three-phase winding of the drive motor to form a three-phase interleaved parallel Boost circuit.

[0128] Based on the working characteristics of electric vehicle motor controllers, coordinated control of the U, V, and W three-phase boost circuits is achieved through a single control core.

[0129] It should be noted that, compared with single-phase Boost control, the three-phase interleaved parallel fast charging boost method has the advantages of lower output voltage ripple and faster dynamic response speed.

[0130] like Figure 5 , 6 As shown in Figure 7, the Boost function schematic diagram shows that by controlling the power conversion module of the motor controller and the shutdown of the U, V, and W phase upper bridge arms of the drive motor, the three-phase interleaved parallel Boost function can be realized. That is, the fast charging boost is achieved by controlling the duty cycle of the control signals of the U, V, and W phase upper bridge arms within a shutdown cycle.

[0131] Among them, the control signals of the three-phase upper bridge arm of U, V, and W are staggered by 120°, and the control signals of each channel differ by 1 / 3 in time.

[0132] Several mature control methods exist for three-phase interleaved parallel boost converter circuits, such as bilinear PI closed-loop control. The vehicle charging method of this invention introduces the ripple coefficient of the DC bus voltage on the motor controller side during fast charging, realizing a three-loop control for fast charging boost. PI regulators are designed for the voltage ripple coefficient, command voltage, and desired currents of the U, V, and W phases respectively, forming a three-loop control to achieve the fast charging boost function. The specific implementation architecture is as follows: Figure 10 As shown.

[0133] The vehicle charging method of this invention, wherein the linear control closed-loop control includes:

[0134] Voltage closed-loop control, current closed-loop control, and voltage ripple closed-loop control.

[0135] like Figure 10 As shown, Uc represents the voltage command, i.e. the target voltage for boost control, and U represents the actual DC bus voltage value collected by the motor controller. The difference between these two voltages is PI-regulated to obtain the desired current value i. This control is a voltage closed-loop control.

[0136] In addition, i u i represents the current value of phase U of the stator winding of the drive motor. v i represents the current value of phase V of the stator winding of the drive motor. w This represents the current value of phase W of the stator winding of the drive motor; the difference between the three current values ​​and the desired current value i is used for PI regulation to obtain the duty cycle commands Du, Dv, and Dw (duty cycle signals within a single PWM control cycle) of the upper bridge arm control signals of the three phases U, V, and W of the motor controller. These duty cycle signals are used to realize the on and off of the upper bridge arms of the three phases U, V, and W, ultimately realizing the three-phase interleaved parallel fast charging boost control; this control is a current closed-loop control.

[0137] The PWM control cycle of the motor controller is adjusted in real time by adjusting the DC bus voltage ripple coefficient during the boost control process, thereby reducing the output voltage ripple. Here, Yc represents the target ripple coefficient value, and Y represents the actual voltage ripple coefficient. After PI regulation, the PWM control cycle H is obtained, which will be used in the voltage closed-loop regulation and current closed-loop regulation control processes.

[0138] Optionally, the linear closed-loop control includes voltage closed-loop control, which includes:

[0139] Determine the target voltage, and determine the first voltage difference based on the voltage value;

[0140] Determine the initial current value, the proportional coefficient of the voltage closed-loop control, the integral coefficient of the voltage closed-loop control, and the pulse width modulation period;

[0141] Based on the initial current value, the proportional coefficient of the voltage closed-loop control, the integral coefficient of the voltage closed-loop control, and the pulse width modulation period, voltage closed-loop control is applied to the first voltage difference to obtain the target current value.

[0142] Wherein, the proportional coefficient and the integral coefficient of the voltage closed-loop control are both greater than zero;

[0143] The pulse width modulation period is the output of voltage ripple control.

[0144] In one embodiment of the present invention, the difference between the voltage command Uc and the actual DC bus voltage U during the boost control process is defined as ΔU, i.e., ΔU = Uc - U. Then, through PI closed-loop control, the following is obtained:

[0145]

[0146] i int K represents the initial value of the current command. P-U K represents the proportional coefficient in voltage closed-loop control. P-U >0; K I-U K represents the integral coefficient in voltage closed-loop control. I-U >0; H represents the PWM control period, where H is the output of the "voltage ripple closed-loop control". The initial value of the current command is obtained through PI regulation, and then its range is limited, defining i... max with i min Let i be the maximum and minimum values ​​of the current command, and i max >i min >0.

[0147]

[0148] Where i represents the current command obtained through voltage closed-loop control, which will be used for subsequent current closed-loop control of the U, V, and W phases.

[0149] Optionally, the linear closed-loop control includes current closed-loop control, which includes:

[0150] Obtain the current of the motor controller, and determine the first current difference based on the target current value;

[0151] Determine the initial duty cycle of the target upper bridge arm of the motor controller, the proportional coefficient of the current closed-loop control, the integral coefficient of the current closed-loop control, and the pulse width modulation period.

[0152] Based on the initial duty cycle, the proportional coefficient of the current closed-loop control, the integral coefficient of the current closed-loop control, and the pulse width modulation period, the first current difference is subjected to current closed-loop control to obtain the target duty cycle of the target upper bridge arm.

[0153] Wherein, the proportional coefficient and the integral coefficient of the current closed-loop control are both greater than zero.

[0154] In one embodiment of the present invention, the deviations between the current command and the three-phase currents U, V, and W of the motor are defined as ΔIu, ΔIv, and ΔIw, respectively:

[0155]

[0156] The specific implementation of current closed-loop control will be explained using phase U as an example:

[0157]

[0158] Among them, D u-int K represents the initial value of the duty cycle control command for the upper arm of phase U. P-iu K represents the proportional coefficient of the U-phase current closed-loop control, and K P-iu >0; K I-iu K represents the integral coefficient of the U-phase current closed-loop control, and K I-iu >0; H represents the PWM control period, where H is the output of the "voltage ripple closed-loop control". The initial value of the duty cycle control command for the upper arm of phase U is obtained through PI regulation. Then, its range is limited, and D is defined. max With D min Let D be the maximum and minimum values ​​of the duty cycle control command, and D max >D min >0.

[0159]

[0160] D u This indicates the duty cycle control command obtained through current closed-loop control, which will be used for the final fast-charging boost control. The process for obtaining the duty cycle commands for phase V and phase W is the same as above.

[0161] Optionally, the linear closed-loop control includes voltage ripple closed-loop control, which includes:

[0162] Determine the target voltage ripple coefficient, and determine the first ripple coefficient difference based on the voltage ripple coefficient;

[0163] When the difference in the first ripple coefficient is greater than zero, the initial pulse width modulation period, the proportional coefficient of the voltage ripple closed-loop control, and the integral coefficient of the voltage ripple closed-loop control are determined.

[0164] Based on the initial pulse width modulation period, the proportional coefficient of the voltage ripple closed-loop control, and the integral coefficient of the voltage ripple closed-loop control, the first ripple coefficient difference is used as input for voltage ripple closed-loop control to obtain the target pulse width modulation period.

[0165] The proportional coefficient and integral coefficient of the voltage ripple closed-loop control are both greater than zero.

[0166] For fast-charging boost control of electric vehicles, the expected voltage is generated in the DC high-voltage bus connected to the motor controller and the power battery according to the vehicle's charging requirements, thereby charging the power battery. Therefore, it is necessary to keep the bus voltage as stable as possible during the charging process. To address this requirement, this invention introduces a voltage ripple closed-loop control measure. When the voltage ripple is large, the PWM control period of the drive motor controller is adjusted to minimize the impact of voltage ripple on the charging process.

[0167] In one embodiment of the present invention, Yc represents the target ripple coefficient value, Y represents the actual voltage ripple coefficient, and the purpose of the PI closed loop is to ensure that the voltage ripple coefficient during the fast charging boost process does not exceed Yc. First, the input of the PI controller is calculated, namely the ripple coefficient deviation value ΔY.

[0168]

[0169] Considering that the three-phase interleaved parallel fast charging boost method provided by the vehicle charging method in this embodiment of the invention, although having the advantage of lower output voltage ripple compared to single-phase boost, still cannot completely eliminate ripple, it is necessary to control the ripple within an acceptable range. Here, Yc is the acceptable voltage ripple coefficient threshold. When the actual ripple coefficient Y does not exceed Yc during the fast charging boost control process, it is considered that the current ripple coefficient is within the expected range, and PI regulation is not required. In this case, ΔY = 0. If Y exceeds Yc, PI regulation is required.

[0170]

[0171] Among them, H int K represents the initial value of the PWM control cycle. P-H K represents the proportional coefficient for voltage ripple closed-loop control. P-H >0; K I-H K represents the integral coefficient of the voltage ripple closed-loop control, and K I-H >0. The initial value of the PWM control cycle was obtained through PI regulation, and then its range was limited, defining H. max With H min Let H be the maximum and minimum values ​​of the PWM control period, and H be the maximum and minimum values ​​of the PWM control period. max >H min >0.

[0172]

[0173] Where H represents the PWM control period obtained through voltage ripple closed-loop control, and this PWM period will be used for fast charging boost control.

[0174] The above describes the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications are also within the scope of protection of the present invention.

Claims

1. A vehicle charging method, applied to a vehicle charging system, the vehicle charging system comprising: Boost control circuit, motor controller, drive motor, and power battery; The input terminal of the boost control circuit is connected to the charging pile, and the output terminal is connected to the input terminal of the power battery and the drive motor. The motor controller is connected to the power battery and the drive motor. When the output voltage of the charging pile is lower than a preset voltage, the boost control circuit is used to increase the output voltage of the charging pile. The method includes: If the output voltage of the charging pile is lower than the preset voltage, obtain the voltage value of the DC bus of the motor controller; Based on the voltage value, determine the voltage ripple coefficient of the DC bus of the motor controller; The output voltage of the motor controller is linearly controlled in a closed loop based on the voltage ripple coefficient. The linear closed-loop control includes voltage ripple closed-loop control, which includes: Determine the target voltage ripple coefficient, and determine the first ripple coefficient difference based on the voltage ripple coefficient; When the difference in the first ripple coefficient is greater than zero, the initial pulse width modulation period, the proportional coefficient of the voltage ripple closed-loop control, and the integral coefficient of the voltage ripple closed-loop control are determined. Based on the initial pulse width modulation period, the proportional coefficient of the voltage ripple closed-loop control, and the integral coefficient of the voltage ripple closed-loop control, the first ripple coefficient difference is used as input for voltage ripple closed-loop control to obtain the target pulse width modulation period. Wherein, the proportional coefficient and the integral coefficient of the voltage ripple closed-loop control are both greater than zero; The linear closed-loop control includes voltage closed-loop control, which includes: Determine the target voltage, and determine the first voltage difference based on the voltage value; Determine the initial current value, the proportional coefficient of the voltage closed-loop control, the integral coefficient of the voltage closed-loop control, and the pulse width modulation period; Based on the initial current value, the proportional coefficient of the voltage closed-loop control, the integral coefficient of the voltage closed-loop control, and the pulse width modulation period, voltage closed-loop control is applied to the first voltage difference to obtain the target current value. Wherein, the proportional coefficient and the integral coefficient of the voltage closed-loop control are both greater than zero; The pulse width modulation period is the output of voltage ripple control.

2. The vehicle charging method according to claim 1, characterized in that, The linear closed-loop control includes current closed-loop control, which includes: Obtain the current of the motor controller, and determine the first current difference based on the target current value; Determine the initial duty cycle of the target upper bridge arm of the motor controller, the proportional coefficient of the current closed-loop control, the integral coefficient of the current closed-loop control, and the pulse width modulation period. Based on the initial duty cycle, the proportional coefficient of the current closed-loop control, the integral coefficient of the current closed-loop control, and the pulse width modulation period, the first current difference is subjected to current closed-loop control to obtain the target duty cycle of the target upper bridge arm. Wherein, the proportional coefficient and the integral coefficient of the current closed-loop control are both greater than zero.

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