A high-voltage direct-current boost charging control method for an on-board OBC

Abstract

The application discloses a high-voltage direct-current boosting charging control method for a vehicle-mounted OBC, which comprises the following steps: collecting an input voltage and an output current of a driving circuit, performing voltage outer loop control on the input voltage to obtain a first reference current, and performing current outer loop control on the output current to obtain a second reference current; obtaining a third reference current for current inner loop control according to the first reference current and the second reference current; performing current inner loop control on three phases of the driving circuit according to the third reference current to obtain a driving signal for controlling the on-off state of a switch tube in the driving circuit; and the controller controls the on-off state of the switch tube in the driving circuit according to the driving signal to be compatible with different kinds of charging piles. Compared with the prior art, the application can solve the problems of high-voltage battery high-power charging and charging pile compatible charging at home and abroad.

Description

Technical Field

[0001] This invention relates to the field of power control, and in particular to a high-voltage DC boost charging control method for an on-board computer (OBC). Background Technology

[0002] With the increasing demand for energy conservation, emission reduction, and air pollution control, new energy vehicles are gradually being commercialized, with electric vehicles becoming the mainstay. The problem of charging difficulties for electric vehicles is slowly being addressed with the gradual construction of charging stations. Simultaneously, thanks to the efforts of domestic automakers, the quality of domestic new energy vehicles has made a qualitative leap, achieving remarkable results both domestically and internationally. With the development of battery technology, to shorten charging time, new energy vehicles are gradually being equipped with 600V-900V high-voltage batteries. However, some DC charging stations currently have an output voltage below 500V, requiring the DC station voltage to be boosted to the battery voltage for high-power charging. Furthermore, foreign charging stations only offer constant current functionality, requiring the maintenance of the charging station's output voltage to continuously charge the battery. Therefore, achieving compatibility with both domestic and foreign charging stations is a pressing technical problem that the industry needs to solve. Summary of the Invention

[0003] To address the issue that high-voltage batteries are not compatible with charging stations both domestically and internationally in existing technologies, this invention proposes a high-voltage DC boost charging control method for vehicle-mounted OBCs.

[0004] The technical solution of this invention is to propose a high-voltage DC boost charging control method for an on-board computer (OBC). The on-board OBC includes a drive circuit connected to a high-voltage battery. The drive circuit includes a three-phase full-bridge circuit, and an input inductor is connected to the midpoint of each bridge arm in the three-phase full-bridge circuit. All switching transistors in the drive circuit are connected to a controller that can control their on / off states. The high-voltage DC boost charging control method includes:

[0005] The input voltage and output current of the drive circuit are collected, and the input voltage is subjected to voltage outer loop control to obtain a first reference current, and the output current is subjected to current outer loop control to obtain a second reference current.

[0006] A third reference current for current inner loop control is obtained based on the first reference current and the second reference current;

[0007] Based on the third reference current, the three phases of the drive circuit are respectively subjected to current inner loop control to obtain drive signals for controlling the on / off state of the switching transistors in the drive circuit.

[0008] The controller controls the on / off state of the switching transistor in the drive circuit according to the drive signal to ensure compatibility with different types of charging piles.

[0009] Furthermore, the step of performing voltage outer loop control on the input voltage to obtain the first reference current includes:

[0010] The first difference value is obtained by subtracting the input voltage from the reference voltage of the outer voltage loop;

[0011] The first difference is subjected to PI transformation, and the value after PI transformation is used as the first reference current.

[0012] Furthermore, the step of performing outer-loop current control on the output current to obtain the second reference current includes:

[0013] The second difference value is obtained by subtracting the output current from the reference current of the outer current loop;

[0014] The second difference is subjected to PI transformation, and the value after PI transformation is used as the second reference current.

[0015] Further, obtaining the third reference current for current inner loop control based on the first reference current and the second reference current includes:

[0016] The first reference current and the second reference current are compared, and the minimum value between the first reference current and the second reference current is taken as the third reference current.

[0017] Furthermore, when the output power of the drive circuit is less than the preset power,

[0018] Before performing inner-loop current control on the three phases of the drive circuit according to the third reference current to obtain the drive signal for controlling the on / off state of the switching transistor, the method further includes:

[0019] A circulating current is provided for the drive circuit, the circulating current including: an inverter current located in the first phase of the drive circuit, and a charging current located in the second and third phases of the drive circuit.

[0020] Furthermore, the step of performing inner-loop current control on the three phases of the drive circuit based on the third reference current to obtain drive signals for controlling the on / off state of the switching transistor includes:

[0021] The first inductor current on the input inductor connected to the first bridge arm of the driving circuit is collected. The third reference current is subtracted from the inverter current to obtain the third difference value. The first error between the third difference value and the first inductor current is subjected to PI transformation. The value after PI transformation is phase-shifted by 0° and used as the driving signal of the switching transistor on the first bridge arm in the driving circuit.

[0022] The second inductor current on the input inductor connected to the second bridge arm of the driving circuit is collected. The third reference current and the charging current are summed to obtain the first sum value. The second error between the first sum value and the second inductor current is subjected to PI transformation. The value after PI transformation is phase-shifted by 120° and used as the driving signal of the switching transistor on the second bridge arm in the driving circuit.

[0023] The third inductor current on the input inductor connected to the third bridge arm of the driving circuit is collected. The third reference current is summed with the charging current to obtain a second sum value. The third error between the second sum value and the third inductor current is subjected to PI transformation. The value after PI transformation is phase-shifted by 240° and used as the driving signal of the switching transistor on the third bridge arm of the driving circuit.

[0024] Furthermore, when the output power of the drive circuit is greater than the preset power,

[0025] The step of performing inner-loop current control on the three phases of the drive circuit based on the third reference current to obtain drive signals for controlling the on / off state of the switching transistor includes:

[0026] The first inductor current on the input inductor connected to the first bridge arm of the driving circuit is collected, and the fourth error between the third reference current and the first inductor current is converted by PI. The value after PI conversion with a phase offset of 0° is used as the driving signal of the switching transistor on the first bridge arm of the driving circuit.

[0027] The second inductor current on the input inductor connected to the second bridge arm of the driving circuit is collected. The fifth error between the third reference current and the second inductor current is converted by PI. The value after PI conversion is phase-shifted by 120° and used as the driving signal of the switching transistor on the second bridge arm of the driving circuit.

[0028] The third inductor current on the input inductor connected to the third bridge arm of the driving circuit is collected. The sixth error between the third reference current and the third inductor current is converted by PI. The value after PI conversion is phase-shifted by 240° and used as the driving signal for the switching transistor on the third bridge arm of the driving circuit.

[0029] Compared with the prior art, the present invention has at least the following beneficial effects:

[0030] This invention proposes a high-voltage DC boost charging control method for vehicle-mounted OBC. By detecting the input voltage and output current of the drive circuit, a drive signal compatible with domestic and foreign charging piles is calculated. The controller then controls the corresponding switching transistor to operate under the drive signal, thereby achieving the effect of charging compatible with domestic and foreign charging piles. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a flowchart of the overall high-voltage DC boost charging control method of the present invention;

[0033] Figure 2 This is a schematic diagram of the overall circuit topology of the vehicle-mounted OBC of the present invention;

[0034] Figure 3 This is the control logic diagram of the voltage outer loop in the vehicle-mounted OBC of the present invention;

[0035] Figure 4 This is the control logic diagram of the outer current loop in the vehicle-mounted OBC of the present invention;

[0036] Figure 5 This is a calculation logic diagram of the third reference current in the vehicle-mounted OBC of the present invention;

[0037] Figure 6 This is a logic diagram for calculating the drive signal when the output power of the vehicle-mounted OBC is less than the preset power.

[0038] Figure 7 This is a logic diagram for calculating the drive signal when the output power of the vehicle-mounted OBC exceeds the preset power, as per the present invention. Detailed Implementation

[0039] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0040] Therefore, a feature pointed out in this specification is used to describe one feature of one embodiment of the invention, and does not imply that every embodiment of the invention must have the described feature. Furthermore, it should be noted that this specification describes many features. Although certain features may be combined to illustrate possible system designs, these features may also be used in other combinations not explicitly stated. Therefore, unless otherwise stated, the described combinations are not intended to be limiting.

[0041] The principles and structure of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0042] Please see Figure 1 To address the issues of high-power charging of high-voltage batteries and compatibility with domestic and international charging stations, this invention proposes a high-voltage DC boost charging control method for an on-board charger (OBC), which includes, but is not limited to, the following steps:

[0043] S101. Collect the input voltage and output current of the driving circuit, perform voltage outer loop control on the input voltage to obtain a first reference current, and perform current outer loop control on the output current to obtain a second reference current.

[0044] Specifically, in the above-mentioned high-voltage DC boost charging control method, the first reference current is obtained by performing voltage outer loop control on the input voltage, including:

[0045] The first difference value is obtained by subtracting the input voltage from the reference voltage of the outer voltage loop;

[0046] The first difference is subjected to PI transformation, and the value after PI transformation is used as the first reference current.

[0047] Please see Figure 3 Vin is the input voltage, REF is the reference voltage of the outer voltage loop, For the PI transformation formula (K) p For proportionality coefficient, K i Here, is the integral coefficient, s is the Laplace constant, and Iref1 is the first reference current. The main function of this outer voltage loop is to maintain the input voltage of the charging pile, especially for charging piles abroad that do not have a constant voltage loop. When the input voltage is unstable, the output current will stop, resulting in discontinuous charging. The obtained first reference current can be used to calculate the subsequent third reference current.

[0048] Furthermore, in the above-mentioned high-voltage DC boost charging control method, the second reference current is obtained by performing an outer current loop control on the output current, including:

[0049] The second difference value is obtained by subtracting the output current from the reference current of the outer current loop;

[0050] The second difference is subjected to PI transformation, and the value after PI transformation is used as the second reference current.

[0051] Please see Figure 4 Iout is the output current, REF I is the reference current of the outer current loop, Here is the PI conversion formula, and Iref2 is the second reference current. The main function of the outer current loop is to limit the maximum current output. If the charging station has constant voltage and constant current functions, this loop can be used for constant current charging. If the charging station only has constant current functions and no constant voltage, this can be used as a maximum current limit to prevent the charging current from exceeding the module's input power and damaging the module. The obtained second reference current can be used for the subsequent calculation of the third reference current.

[0052] S102. Obtain a third reference current for current inner loop control based on the first reference current and the second reference current.

[0053] Specifically, in the above-mentioned high-voltage DC boost charging control method, obtaining a third reference current for the inner current loop control based on the first reference current and the second reference current includes:

[0054] Compare the first reference current and the second reference current, and take the minimum value of the first reference current and the second reference current as the third reference current.

[0055] Please see Figure 5 Iref1 is the first reference current, Iref2 is the second reference current, and Iref is the third reference current. The value of Iref is the minimum value between the first reference current and the second reference current. The obtained third reference current is used as the input of the current inner loop control to obtain the drive signal.

[0056] S103. Perform current inner loop control on the three phases of the drive circuit according to the third reference current to obtain drive signals for controlling the on / off state of the switching transistors in the drive circuit.

[0057] Specifically, for cases where the output power of the drive circuit is less than the preset power, to ensure compatibility with domestic and international charging piles (i.e., compatibility with constant voltage / constant current charging piles and constant current charging piles), before performing inner-loop current control on each of the three phases of the drive circuit based on the third reference current to obtain the drive signal used to control the on / off state of the switching transistors, the following steps are also included: providing a circulating current for the drive circuit. This circulating current includes the inverter current located in the first phase of the drive circuit, and the charging current located in both the second and third phases of the drive circuit. The inverter current is IoffsetA, and the charging current is IoffsetBC, satisfying IoffsetA = 2IoffsetBC.

[0058] In the above-mentioned high-voltage DC boost charging control method, the three phases of the drive circuit are subjected to current inner-loop control based on the third reference current to obtain drive signals for controlling the on / off state of the switching transistors, including:

[0059] The first inductor current on the input inductor connected to the first bridge arm of the drive circuit is collected. The third reference current is subtracted from the inverter current to obtain the third difference value. The first error between the third difference value and the first inductor current is PI transformed. The value after PI transformation is phase-shifted by 0° and used as the drive signal of the switching transistor on the first bridge arm in the drive circuit.

[0060] The second inductor current on the input inductor connected to the second bridge arm of the drive circuit is collected. The third reference current and the charging current are summed to obtain the first sum value. The second error between the first sum value and the second inductor current is PI transformed. The value after PI transformation is phase-shifted by 120° and used as the drive signal for the switching transistor on the second bridge arm in the drive circuit.

[0061] The third inductor current on the input inductor connected to the third bridge arm of the drive circuit is collected. The third reference current is summed with the charging current to obtain the second sum. The third error between the second sum and the third inductor current is subjected to PI transformation. The value after PI transformation is phase-shifted by 240° and used as the drive signal for the switching transistor on the third bridge arm of the drive circuit.

[0062] Please see Figure 6 Iref is the third reference current, IoffsetA is the inverter current, IpffsetBC is the charging current, IA is the first inductor current, IB is the second inductor current, IC is the third inductor current, PWM A is the drive signal for the switch on the first bridge arm, PWM B is the drive signal for the switch on the second bridge arm, and PWM C is the drive signal for the switch on the third bridge arm.

[0063] For the drive signal of the switching transistor on the first bridge arm, Iref-IoffsetA is first calculated, then the obtained third difference is converted with the first error of IA by PI transformation, and finally the phase offset of the value obtained by PI transformation is set to 0° to obtain the drive signal PWM A.

[0064] For the drive signal of the switching transistor on the second bridge arm, Iref+IoffsetBC is first calculated, then the first sum and the second error of IB are converted by PI transformation, and finally the value obtained by PI transformation is set with a phase offset of 120° to obtain the drive signal PWM B.

[0065] For the drive signal of the switching transistor on the third bridge arm, Iref+IoffsetBC is first calculated, then the second sum and the third error of IC are converted by PI, and finally the value obtained by PI conversion is set with a phase offset of 240° to obtain the drive signal PWM C.

[0066] Furthermore, when the output power of the drive circuit is greater than the preset power, the three phases of the drive circuit are subjected to current inner-loop control according to the third reference current to obtain drive signals for controlling the on / off state of the switching transistors, including:

[0067] The first inductor current on the input inductor connected to the first bridge arm of the drive circuit is collected. The fourth error between the third reference current and the first inductor current is converted by PI. The value after PI conversion is phase-shifted by 0° and used as the drive signal for the switching transistor on the first bridge arm of the drive circuit.

[0068] The second inductor current on the input inductor connected to the second bridge arm of the drive circuit is collected. The fifth error between the third reference current and the second inductor current is converted by PI. The value after PI conversion is phase-shifted by 120° and used as the drive signal for the switching transistor on the second bridge arm of the drive circuit.

[0069] The third inductor current on the input inductor connected to the third bridge arm of the drive circuit is collected. The sixth error between the third reference current and the third inductor current is converted by PI. The value after PI conversion is phase-shifted by 240° and used as the drive signal for the switching transistor on the third bridge arm of the drive circuit.

[0070] Please see Figure 7 Iref is the third reference current, IA is the first inductor current, IB is the second inductor current, IC is the third inductor current, PWM A is the drive signal for the switch on the first bridge arm, PWM B is the drive signal for the switch on the second bridge arm, and PWM C is the drive signal for the switch on the third bridge arm.

[0071] Since no circulating current is set in this case, there is no need to consider the inverter current and charging current when calculating PWM A, PWM B, and PWM C. In this case, the drive signal of the switch on the first bridge arm is directly transformed by PI conversion of the fourth error of Iref and IA, and then the phase of the PI-converted value is shifted by 0° as the drive signal PWM A of the switch on the first bridge arm in the drive circuit.

[0072] For the drive signal of the switch on the second bridge arm, it is directly transformed by PI conversion of the fifth error of Iref and IB, and then the phase of the PI-converted value is shifted by 120° as the drive signal PWMB of the switch on the second bridge arm in the drive circuit.

[0073] For the drive signal of the switch on the third bridge arm, it is directly transformed by PI conversion of Iref and the sixth error of IC, and then the phase of the PI-converted value is shifted by 240° as the drive signal PWMC of the switch on the third bridge arm in the drive circuit.

[0074] S104. The controller controls the on / off state of the switching transistor in the drive circuit according to the drive signal to be compatible with different types of charging piles.

[0075] For details, please see Figure 2 The driving circuit proposed in this invention adopts a three-phase full-bridge circuit, which includes three bridge arms: a first bridge arm composed of switching transistors Q1 and Q2, a second bridge arm composed of switching transistors Q3 and Q4, and a third bridge arm composed of switching transistors Q5 and Q6. These three bridge arms correspond to the three-phase input of the vehicle's OBC (On-Board Circuit). An input inductor L1 is connected to the midpoint of the first bridge arm, an input inductor L2 is connected to the midpoint of the second bridge arm, and an input inductor L3 is connected to the midpoint of the third bridge arm. Figure 2 In this context, IA, IB, and IC represent the inductor currents on input inductors L1, L2, and L3, respectively—that is, the first inductor current, the second inductor current, and the third inductor current. Furthermore, switching transistors Q1, Q2, Q3, Q4, Q5, and Q6 are also connected to the controller (i.e.,...). Figure 2 The DSP controller (in this context) sends drive signals to switches Q1, Q2, Q3, Q4, Q5, and Q6, thereby controlling their on / off states to achieve different charging effects. Here, Vin is the input voltage of the drive circuit, Iout is the output current of the drive circuit, and Vbat is the battery voltage of the high-voltage battery. The controller first acquires Vin, Iout, Vbat, IA, IB, and IC, and then calculates the drive signal used to control the on / off state of the switches in the drive circuit using the aforementioned high-voltage DC boost charging control method. This drive signal controls the on / off state of the switches to adapt to different charging piles, thus achieving the goal of high-power charging of high-voltage batteries and compatibility with charging piles both domestically and internationally.

[0076] After calculating the drive signals PWM A, PWM B, and PWM C using the above method, the controller can control the on / off states of the switching transistors in the first, second, and third bridge arms according to these signals. This solves the problem of high-power charging of high-voltage batteries and compatibility with domestic and international charging piles. In other words, the above high-voltage DC boost charging control method utilizes the controller to control the on / off states of the switching transistors in the driven circuit based on the drive signals to ensure compatibility with different types of charging piles. Figure 2 The controller (DSP controller) in the system controls the on / off states of switching transistors Q1, Q2, Q3, Q4, Q5, and Q6 respectively.

[0077] Compared with the prior art, the present invention proposes a high-voltage DC boost charging control method for vehicle-mounted OBC. By detecting the input voltage and output current of the drive circuit, the drive signal that is compatible with domestic and foreign charging piles is calculated, and the corresponding switching transistor is controlled by the controller to work under the drive signal, so as to achieve the effect of compatible charging of domestic and foreign charging piles.

[0078] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-voltage DC boost charging control method for an on-board computer (OBC), wherein the OBC includes a drive circuit connected to a high-voltage battery, the drive circuit includes a three-phase full-bridge circuit, and an input inductor is connected to the midpoint of each bridge arm in the three-phase full-bridge circuit; all switching transistors in the drive circuit are connected to a controller that can control their on / off states, characterized in that... The high-voltage DC boost charging control method includes: The input voltage and output current of the drive circuit are collected, and the input voltage is subjected to voltage outer loop control to obtain a first reference current, and the output current is subjected to current outer loop control to obtain a second reference current. A third reference current for current inner loop control is obtained based on the first reference current and the second reference current; Based on the third reference current, the three phases of the drive circuit are respectively subjected to current inner loop control to obtain drive signals for controlling the on / off state of the switching transistors in the drive circuit. The controller controls the on / off state of the switching transistor in the drive circuit according to the drive signal to ensure compatibility with different types of charging piles; When the output power of the drive circuit is less than the preset power Before performing inner-loop current control on the three phases of the drive circuit according to the third reference current to obtain the drive signal for controlling the on / off state of the switching transistor, the method further includes: A circulating current is provided for the drive circuit, the circulating current including: an inverter current located in the first phase of the drive circuit, and a charging current located in the second and third phases of the drive circuit.

2. The high-voltage DC boost charging control method according to claim 1, characterized in that, The step of obtaining the first reference current by performing voltage outer loop control on the input voltage includes: The first difference value is obtained by subtracting the input voltage from the reference voltage of the outer voltage loop; The first difference is subjected to PI transformation, and the value after PI transformation is used as the first reference current.

3. The high-voltage DC boost charging control method according to claim 1, characterized in that, The step of obtaining the second reference current by performing current outer loop control on the output current includes: The second difference value is obtained by subtracting the output current from the reference current of the outer current loop; The second difference is subjected to PI transformation, and the value after PI transformation is used as the second reference current.

4. The high-voltage DC boost charging control method according to claim 1, characterized in that, The step of obtaining a third reference current for current inner loop control based on the first reference current and the second reference current includes: The first reference current and the second reference current are compared, and the minimum value between the first reference current and the second reference current is taken as the third reference current.

5. The high-voltage DC boost charging control method according to claim 1, characterized in that, The step of performing inner-loop current control on the three phases of the drive circuit based on the third reference current to obtain drive signals for controlling the on / off state of the switching transistor includes: The first inductor current on the input inductor connected to the first bridge arm of the driving circuit is collected. The third reference current is subtracted from the inverter current to obtain the third difference value. The first error between the third difference value and the first inductor current is subjected to PI transformation. The value after PI transformation is phase-shifted by 0° and used as the driving signal of the switching transistor on the first bridge arm in the driving circuit. The second inductor current on the input inductor connected to the second bridge arm of the driving circuit is collected. The third reference current and the charging current are summed to obtain the first sum value. The second error between the first sum value and the second inductor current is subjected to PI transformation. The value after PI transformation is phase-shifted by 120° and used as the driving signal of the switching transistor on the second bridge arm in the driving circuit. The third inductor current on the input inductor connected to the third bridge arm of the driving circuit is collected. The third reference current is summed with the charging current to obtain a second sum value. The third error between the second sum value and the third inductor current is subjected to PI transformation. The value after PI transformation is phase-shifted by 240° and used as the driving signal of the switching transistor on the third bridge arm of the driving circuit.

6. The high-voltage DC boost charging control method according to claim 1, characterized in that, When the output power of the drive circuit is greater than the preset power The step of performing inner-loop current control on the three phases of the drive circuit based on the third reference current to obtain drive signals for controlling the on / off state of the switching transistor includes: The first inductor current on the input inductor connected to the first bridge arm of the driving circuit is collected, and the fourth error between the third reference current and the first inductor current is converted by PI. The value after PI conversion with a phase offset of 0° is used as the driving signal of the switching transistor on the first bridge arm of the driving circuit. The second inductor current on the input inductor connected to the second bridge arm of the driving circuit is collected. The fifth error between the third reference current and the second inductor current is converted by PI. The value after PI conversion is phase-shifted by 120° and used as the driving signal of the switching transistor on the second bridge arm of the driving circuit. The third inductor current on the input inductor connected to the third bridge arm of the driving circuit is collected. The sixth error between the third reference current and the third inductor current is converted by PI. The value after PI conversion is phase-shifted by 240° and used as the driving signal for the switching transistor on the third bridge arm of the driving circuit.

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