On-vehicle DC-DC control circuit, control method and electric vehicle

Abstract

The present application provides a vehicle-mounted DC-DC control circuit, a control method, and an electric vehicle, wherein the controller is used to correct the voltage value of the first capacitor cycle by cycle to obtain an overvoltage protection value and an undervoltage protection value; the input voltage across the first capacitor is detected in real time by a voltage detector; when it is monitored that the voltage value across the first capacitor is between the overvoltage protection value and the undervoltage protection value, the switch tube of the bridge circuit, the switch tube of the rectifier circuit, and the switch tube of the clamping absorption circuit are in a conductive state; in the dynamic startup process, the capacitor pre-charging stage is performed first, and then a closed-loop startup stage with restrictions is performed. The present application solves to a certain extent the problem that the vehicle-mounted DC-DC quality risk may be caused by a rapid jump or drop in the high-voltage bus voltage of the entire vehicle.

Description

Technical Field

[0001] The present application belongs to the technical field of electric vehicles, and in particular, relates to a vehicle-mounted DC-DC control circuit, a control method and an electric vehicle. Background Art

[0002] With the rapid development of new energy vehicles, the reliability of vehicle-mounted DC-DC has received more and more attention. The vehicle-mounted DC-DC converter is used to convert the energy of the high-voltage battery of electric vehicles into the energy of the low-voltage battery, or to convert the low voltage on the low-voltage battery into the high voltage on the high-voltage battery. During the operation of the vehicle-mounted DC-DC converter, interference such as impact current and impact voltage may occur, and some components may not work properly, such as excessive loss of the switch tube, damage to the driver chip, or magnetic saturation of the transformer, which will affect the reliability of the vehicle-mounted DC-DC converter.

[0003] Especially on the high-voltage side of electric vehicles, there are many devices, and extreme intermittent loads or fault conditions may cause the voltage to jump or drop rapidly. The sudden change in voltage may cause quality risks of on-board DCDC.

[0004] The above statements are only used to provide background technical information related to the present application. Unless otherwise stated herein, the contents described in this section are not prior art for the contents of other parts of the present application. Summary of the invention

[0005] The vehicle-mounted DC-DC control circuit, control method and electric vehicle proposed in the present invention first perform a capacitor pre-charging stage and then a closed-loop startup stage with restrictions during the dynamic startup process, and at the same time, the input voltage across the first capacitor is detected in real time by a voltage detector, and the input overvoltage and undervoltage protection values ​​are corrected cycle by cycle according to the voltage of the input capacitor C1. To a certain extent, the problem of the vehicle-mounted DCDC quality risk caused by the rapid rise or fall of the high-voltage bus voltage of the whole vehicle is solved.

[0006] This application scheme can effectively avoid the risk of damage to the on-board DCDC power devices caused by rapid fluctuations in high voltage.

[0007] In addition, the present application can control the stress of the MOS switch tube of the rectifier circuit in the circuit to remain within the required range, thereby improving the working reliability of the vehicle-mounted DC-DC converter.

[0008] According to a first aspect of an embodiment of the present application, a vehicle-mounted DC-DC control circuit is provided, comprising a DC-DC converter, a voltage detector and a controller; the DC-DC converter comprises a first capacitor, a bridge circuit, a first inductor, a transformer, a rectifier circuit, a clamping absorption circuit and a second capacitor connected in sequence; the first capacitor is connected in parallel with the bridge circuit, and the voltage across the first capacitor determines the primary side voltage of the transformer and the secondary side voltage of the transformer;

[0009] The controller is connected to a voltage detector;

[0010] The controller is used to control the DC-DC converter to enter the pre-charging stage, soft-start stage and working stage of the startup process in sequence;

[0011] The controller is used to detect the input voltage across the first capacitor in real time through a voltage detector during the pre-charging stage, the soft-start stage and the working stage; correct the overvoltage protection value and the undervoltage protection value period by period according to the voltage value of the first capacitor, and when it is monitored that the voltage value across the first capacitor is between the overvoltage protection value and the undervoltage protection value, the switch tube of the bridge circuit, the switch tube of the rectifier circuit and the switch tube of the clamping absorption circuit are in a conductive state; otherwise, the current operation is stopped;

[0012] Wherein, in the pre-charging stage, the voltage of the third capacitor in the clamping absorption circuit is charged to the first voltage interval;

[0013] In the soft start stage, the minimum pulse width of the primary side driving voltage of the DC-DC converter is set; during closed-loop startup, the initial pulse width of the primary side driving voltage starts from the minimum pulse width and limits the pulse width mutation within the threshold.

[0014] In some embodiments of the present application, after the bridge circuit is connected to the first inductor, it is connected to the primary winding of the transformer;

[0015] The bridge circuit includes a first bridge arm and a second bridge arm connected in parallel; both ends of the first bridge arm and the second bridge arm receive the input voltage or output voltage of the primary side of the transformer; the first bridge arm includes a first switch tube and a fourth switch tube, and the second bridge arm includes a third switch tube and a second switch tube;

[0016] The common node of the first switch bridge arm is connected to one end of the primary winding of the transformer, and the common node of the second switch bridge arm is connected to the first inductor and then to the other end of the primary winding of the transformer.

[0017] In some embodiments of the present application, the rectifier circuit is connected between two ends of the secondary winding of the transformer and ground; the secondary winding of the transformer includes a first secondary winding and a second secondary winding, and the connection point between the first secondary winding and the second secondary winding is a center tap of the transformer;

[0018] The rectifier circuit includes a first rectifier tube, a second rectifier tube and a second inductor;

[0019] The two ends of the secondary winding of the transformer are respectively connected to one end of the first rectifier tube and one end of the second rectifier tube, and the other end of the first rectifier tube and the other end of the second rectifier tube are grounded; the center tap of the transformer is connected to the second inductor and then to one end of the second capacitor, and the other end of the second capacitor is grounded.

[0020] In some embodiments of the present application, the clamping absorption circuit is connected between two ends of the secondary winding of the transformer and ground; the secondary winding of the transformer includes a first secondary winding and a second secondary winding, and the connection point between the first secondary winding and the second secondary winding is a center tap of the transformer;

[0021] The clamping absorption circuit includes a first clamping switch tube, a second clamping switch tube and a third capacitor;

[0022] The two ends of the secondary winding of the transformer are respectively connected to one end of the first clamp switch tube and one end of the second clamp switch tube; after the other ends of the first clamp switch tube and the second clamp switch tube are connected, they are connected to the first end of the third capacitor, and the second end of the third capacitor is grounded.

[0023] In some implementations of the present application, the overvoltage protection value and the undervoltage protection value are corrected periodically according to the voltage value of the first capacitor, including:

[0024] When the input voltage jumps, the equivalent circuit of the DC-DC converter impact path is obtained;

[0025] Determine the allowable fluctuation value of the input voltage based on the equivalent circuit of the DC-DC converter impact path ; Allowable fluctuation value The calculation formula is:

[0026] ;

[0027] in, The value of depends on the current carrying capacity of all switches in the bridge circuit and the clamping absorption circuit;

[0028] Wherein, L is the sum of the first inductance L1, the primary line inductance of the transformer, and the secondary line inductance of the transformer converted to the primary side inductance; C is the capacity of C3 converted to the primary side;

[0029] According to the allowable fluctuation value of input voltage , correct the overvoltage protection value and undervoltage protection value, and get the overvoltage protection value as V+ , the undervoltage protection value is V- ; V is the current input voltage.

[0030] In some embodiments of the present application, charging the voltage of the third capacitor in the clamping absorption circuit to the first voltage interval includes:

[0031] The third capacitor is charged by a small duty cycle of the switch tube of the bridge circuit, so that the pre-charge voltage of the third capacitor is within the first voltage range;

[0032] The calculation formula for the first voltage interval is:

[0033] <( ) / N*2;

[0034] in, is the pre-charge voltage of the third capacitor, V is the current input voltage, is the allowable fluctuation value of the input voltage, and N is the transformer turns ratio.

[0035] In some embodiments of the present application, setting the minimum pulse width of the primary side driving voltage of the DC-DC converter includes:

[0036] Determine the minimum on-time of the switch tube in the clamping absorption circuit, and determine the hysteresis turn-on dead zone and advance turn-off dead zone of the switch tube in the clamping absorption circuit relative to the switch tube in the bridge circuit;

[0037] The minimum on-time, the delayed turn-on dead zone, and the advanced turn-off dead zone are superimposed to determine the minimum pulse width.

[0038] According to a second aspect of an embodiment of the present application, there is provided a vehicle-mounted DC-DC control method applied to a vehicle-mounted DC-DC control circuit, wherein the vehicle-mounted DC-DC control circuit comprises a DC-DC converter, a voltage detector, and a controller; the DC-DC converter comprises a first capacitor, a bridge circuit, a first inductor, a transformer, a rectifier circuit, a clamping absorption circuit, and a second capacitor connected in sequence; the first capacitor is connected in parallel with the bridge circuit, and the voltage across the first capacitor determines the primary side voltage of the transformer and the secondary side voltage of the transformer;

[0039] The control method comprises the following steps:

[0040] The startup process of the DC-DC converter first enters the pre-charging stage, and the voltage of the third capacitor in the clamping absorption circuit is charged to the first voltage range;

[0041] The startup process of the DC-DC converter enters the soft start stage again, and the minimum pulse width of the primary side driving voltage of the DC-DC converter is set;

[0042] When the closed loop is started, the initial pulse width of the primary side driving voltage starts from the minimum pulse width and limits the sudden change of the pulse width to within the threshold;

[0043] Make the DC-DC converter enter the working stage;

[0044] During the pre-charging stage, the soft-start stage and the working stage, the input voltage across the first capacitor is detected in real time by a voltage detector; the overvoltage protection value and the undervoltage protection value are corrected cycle by cycle according to the voltage value of the first capacitor; when it is monitored that the voltage value across the first capacitor is between the overvoltage protection value and the undervoltage protection value, the switch tube of the bridge circuit, the switch tube of the rectifier circuit and the switch tube of the clamping absorption circuit are put into a conductive state; otherwise, the current operation is stopped.

[0045] According to a third aspect of an embodiment of the present application, there is provided a vehicle-mounted DC-DC control device, comprising:

[0046] A storage unit for storing executable instructions; and

[0047] The processing unit is used to connect with the memory to execute executable instructions to complete the above control method.

[0048] According to a fourth aspect of an embodiment of the present application, there is provided an electric vehicle comprising any one of the above-mentioned on-board DC-DC control circuits.

[0049] By adopting the vehicle-mounted DC-DC control circuit, control method and electric vehicle of the present application, the controller detects the input voltage across the first capacitor in real time through a voltage detector. When it is monitored that the voltage value across the first capacitor is between the overvoltage protection value and the undervoltage protection value, all the switch tubes of the bridge circuit, all the switch tubes of the rectifier circuit and all the switch tubes of the clamping absorption circuit are in a conductive state; in the dynamic startup process, the present application first performs a capacitor pre-charging stage and then performs a closed-loop startup stage with restrictions. At the same time, the input voltage across the first capacitor is detected in real time through a voltage detector, and the input overvoltage and undervoltage protection values ​​are corrected cycle by cycle according to the voltage of the input capacitor C1, which solves the problem of vehicle-mounted DCDC quality risk caused by a rapid jump or drop in the high-voltage bus voltage of the whole vehicle to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0051] Figure 1 : shows a schematic diagram of the principle of a vehicle-mounted DC-DC control circuit according to an embodiment of the present application;

[0052] Figure 2 A circuit diagram of a DC-DC converter charging according to an embodiment of the present application is shown in FIG.

[0053] Figure 3 : shows a schematic diagram of an equivalent circuit of an impact path of a DC-DC converter according to an embodiment of the present application;

[0054] Figure 4 : shows a principle flow chart of a vehicle-mounted DC-DC control method according to an embodiment of the present application;

[0055] Figure 5 A schematic diagram of the steps of the vehicle-mounted DC-DC control method according to an embodiment of the present application is shown in FIG.

[0056] Figure 6 A schematic diagram of the steps for setting the minimum pulse width of the primary side driving voltage of the DC-DC converter is shown in FIG.

[0057] Figure 7 Graph shows the structure of the vehicle-mounted DC-DC control device according to an embodiment of the present application. DETAILED DESCRIPTION

[0058] Regarding this application, it is considered that the current on-board DC-DC converters are mainly single-stage, with phase-shifted full-bridge design or hard-switching full-bridge / half-bridge as the main design, and the secondary side is mainly full-wave, current doubler, and full-bridge rectification. The reliability of the existing main topological forms is focused on solving the main electrical stress problems, such as current or voltage. However, when the on-board DC-DC converter is started, it may cause interference such as impact current and impact voltage, and may also cause some devices to malfunction, such as excessive loss of the switch tube, damage to the driver chip, or magnetic saturation of the transformer, which affects the reliability of the on-board DC-DC converter.

[0059] In particular, electric vehicles have a large number of high-voltage side devices, and extreme intermittent loads or fault conditions may cause the voltage to jump or drop rapidly. This sudden change in voltage may cause quality risk issues for on-board DC-DC.

[0060] The present application can effectively avoid the risk of damage to vehicle-mounted DC-DC power devices caused by rapid fluctuations in high voltage. In addition, the present application can control the stress of the MOS switch tube in the rectifier circuit in the circuit to be within the required range, thereby improving the working reliability of the vehicle-mounted DC-DC converter.

[0061] Specifically, the vehicle-mounted DC-DC control circuit, control method and electric vehicle of the present application, the vehicle-mounted DC-DC control circuit, includes a DC-DC converter, a voltage detector and a controller; the DC-DC converter includes a first capacitor, a bridge circuit, a first inductor, a transformer, a rectifier circuit, a clamping absorption circuit and a second capacitor connected in sequence; the first capacitor is connected in parallel with the bridge circuit, and the voltage across the first capacitor determines the primary voltage of the transformer and the secondary voltage of the transformer; and the controller corrects the input overvoltage and undervoltage protection values ​​according to the voltage of the input capacitor C1 in each control cycle, and in the dynamic startup process, first performs a capacitor pre-charging stage and then performs a closed-loop startup stage with restrictions. To a certain extent, it solves the problem that the high-voltage bus voltage of the whole vehicle jumps or drops rapidly, which may cause the quality risk of the vehicle-mounted DC-DC.

[0062] In order to make the technical solutions and advantages in the embodiments of the present application more clearly understood, the exemplary embodiments of the present application are further described in detail below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present application, rather than an exhaustive list of all the embodiments. It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0063] Example 1

[0064] Figure 1 Schematic diagram of the principle of the vehicle-mounted DC-DC control circuit according to an embodiment of the present application is shown in FIG.

[0065] like Figure 1 As shown, the vehicle-mounted DC-DC control circuit includes a DC-DC converter, a voltage detector 20 and a controller 10 ; the controller 10 is connected to the voltage detector 20 .

[0066] The DC-DC converter includes a first capacitor C1, a bridge circuit 30, a first inductor L1, a transformer, a rectifier circuit 50, a clamping absorption circuit 40 and a second capacitor C2 connected in sequence; the first capacitor C1 is connected in parallel with the bridge circuit 30, and the voltage across the first capacitor C1 determines the primary side voltage and the secondary side voltage of the transformer.

[0067] The controller 10 is used to control the DC-DC converter to sequentially enter the pre-charging stage, the soft-start stage and the working stage of the startup process;

[0068] The controller 10 is also used to detect the input voltage across the first capacitor C1 in real time through the voltage detector 20 during the pre-charging stage, the soft-start stage and the working stage. The overvoltage protection value and the undervoltage protection value are corrected cycle by cycle according to the voltage value of the first capacitor C1. When it is detected that the voltage value across the first capacitor C1 is between the overvoltage protection value and the undervoltage protection value, all the switch tubes of the bridge circuit 30, all the switch tubes of the rectifier circuit 50 and all the switch tubes of the clamping absorption circuit 40 are turned on; otherwise, the current operation is stopped;

[0069] In the pre-charging stage, the voltage of the third capacitor C3 in the clamping absorption circuit 40 is charged to the first voltage range;

[0070] In the soft start stage, the minimum pulse width of the primary side driving voltage of the DC-DC converter is set; during closed-loop startup, the initial pulse width of the primary side driving voltage starts from the minimum pulse width and limits the pulse width mutation within the threshold.

[0071] The application adopts the minimum pulse width to ensure that C3 can be replenished or discharged in each cycle, so that it can quickly reach the theoretical platform voltage;

[0072] Limiting pulse width mutation within a certain range can effectively prevent startup or dynamic magnetization.

[0073] The vehicle-mounted DC-DC control circuit of this embodiment corrects the input overvoltage and undervoltage protection values ​​according to the voltage of the input capacitor C1 in each control cycle, and in the dynamic startup process, first performs the capacitor pre-charging stage and then performs the closed-loop startup stage with restrictions. This can effectively avoid the risk of damage to the vehicle-mounted DCDC power device caused by rapid high-voltage fluctuations.

[0074] In addition, the present application can control the stress of the MOS switch tube of the rectifier circuit 50 in the circuit to be maintained within the required range, thereby improving the working reliability of the vehicle-mounted DC-DC converter.

[0075] When implementing it, Figure 1 As shown, the bridge circuit 30 is connected to the first inductor L1 and then to the primary winding of the transformer.

[0076] The bridge circuit 30 includes a first bridge arm and a second bridge arm connected in parallel; two ends of the first bridge arm and the second bridge arm receive the input voltage or output voltage of the primary side of the transformer and are connected in parallel with the first capacitor C1 .

[0077] The first bridge arm includes a first switch tube P1 and a fourth switch tube P4, and the second bridge arm includes a third switch tube P3 and a second switch tube P2;

[0078] The common node of the first switch bridge arm is connected to one end of the primary winding of the transformer, and the common node of the second switch bridge arm is connected to the first inductor and then to the other end of the primary winding of the transformer.

[0079] The first inductor L1 may be a transformer leakage inductor or an external independent inductor.

[0080] The clamping absorption circuit 40 includes a first clamping switch tube AC1 , a second clamping switch tube AC2 and a third capacitor C3 .

[0081] Specifically, the two ends of the secondary winding of the transformer are respectively connected to one end of the first clamp switch tube AC1 and one end of the second clamp switch tube AC2; after the other ends of the first clamp switch tube AC1 and the second clamp switch tube AC2 are connected, they are connected to the first end of the third capacitor C3, and the second end of the third capacitor C3 is grounded.

[0082] The rectifier circuit 50 is connected between two ends of the secondary winding of the transformer and the ground; the secondary winding of the transformer includes a first secondary winding and a second secondary winding, and the connection point between the first secondary winding and the second secondary winding is a center tap M of the transformer;

[0083] Specifically, the rectifier circuit 50 includes a first rectifier tube SR1 , a second rectifier tube SR2 , and a second inductor L2 .

[0084] The two ends of the secondary winding of the transformer are respectively connected to one end of the first rectifier tube SR1 and one end of the second rectifier tube SR2, and the other end of the first rectifier tube SR1 and the other end of the second rectifier tube SR2 are grounded; the center tap M of the transformer is connected to the second inductor L2 and then to one end of the second capacitor C2, and the other end of the second capacitor C2 is grounded.

[0085] Furthermore, the clamping absorption circuit 40 is connected between two ends of the secondary winding of the transformer and ground; the secondary winding of the transformer includes a first secondary winding and a second secondary winding, and the connection point between the first secondary winding and the second secondary winding is the center tap M of the transformer.

[0086] In other implementations, the controller 10 corrects the overvoltage protection value and the undervoltage protection value periodically according to the voltage value of the first capacitor, specifically including:

[0087] First, when the input voltage jumps, the equivalent circuit of the DC-DC converter impact path is obtained;

[0088] Secondly, according to the equivalent circuit of the DC-DC converter impact path, determine the allowable fluctuation value of the input voltage ; Allowable fluctuation value The calculation formula is:

[0089] ;

[0090] in, The value of depends on the current carrying capacity of all switches in the bridge circuit and the clamping absorption circuit;

[0091] Wherein, L is the sum of the first inductance L1, the primary line inductance of the transformer, and the secondary line inductance of the transformer converted to the primary side inductance; C is the capacity of C3 converted to the primary side;

[0092] Finally, according to the allowable fluctuation value of the input voltage , correct the overvoltage protection value and undervoltage protection value, and get the overvoltage protection value as V+ , the undervoltage protection value is V- ; V is the current input voltage.

[0093] Figure 2 A circuit diagram of a DC-DC converter charging according to an embodiment of the present application is shown in FIG. Figure 3 Schematic diagram of an equivalent circuit of a DC-DC converter impulse path according to an embodiment of the present application is shown in FIG.

[0094] The present application considers that the main risk caused by DC-DC input voltage fluctuation is excessive impact current. Therefore, taking the positive half-cycle operation of the transformer as an example, when the input voltage jumps, the clamping absorption capacitor C3 and the filter capacitor C2 are charged.

[0095] like Figure 2 As shown, the charging path for absorption capacitor C3 is P3, L1, T1, AC2, C3, SR1, P4, and its resonant frequency is f3. The charging path for filter capacitor C2 is P3, L1, T1, L2, C2, SR1, P4, and its resonant frequency is f2. The operating frequency of the DC-DC converter is f1.

[0096] Under normal design, f3>f1>10*f2 exists. Since L2 is a power filter inductor and is controlled by the loop, the charging path of the filter capacitor C2 can be ignored during the switching cycle. The charging path of the absorption capacitor C3 plays a decisive role in the impact current, so the following analysis only considers the C3 path.

[0097] Excessive impact current can easily cause overcurrent stress and damage to the switch tubes P1, P2, P3, and P4 of the bridge circuit; it can also cause overcurrent stress and damage to the switch tubes AC1 and AC2 of the clamping absorption circuit.

[0098] like Figure 3 The figure shows the equivalent circuit of the impact path, which is equivalent to the zero-state response solution of the LCR resonant circuit, where L is the sum of L1, the primary line inductance of the transformer, and the secondary line inductance of the transformer converted to the primary side inductance; R is the sum of the on-impedance of P3, the on-impedance of P4, and the on-impedance of AC2 converted to the primary impedance; and C is the capacitance of C3 converted to the primary side.

[0099] The impulse current waveform complies with:

[0100] ;

[0101] in The maximum value is approximately It happens all the time;

[0102] Right now ;

[0103] in, The value of depends on the current carrying capacity of the switch tubes P1, P2, P3, P4 and AC1, AC2;

[0104] If the equivalent impedance R of the transformer is small, the analysis can be approximated as LC resonance, so The calculation can be simplified to:

[0105] .

[0106] In further implementation, charging the voltage of the third capacitor C3 in the clamping absorption circuit 40 to the first voltage interval includes:

[0107] The third capacitor C3 is charged by the switch tube of the bridge circuit 30 with a small duty cycle, so that the pre-charge voltage of the third capacitor C3 is within the first voltage range;

[0108] The calculation formula for the first voltage interval is:

[0109] <( ) / N*2;

[0110] in, is the pre-charge voltage of the third capacitor C3, V is the input voltage, is the fluctuation range of the input voltage, and N is the transformer turns ratio.

[0111] In specific implementation, setting the minimum pulse width of the primary side driving voltage of the DC-DC converter includes:

[0112] First, determine the minimum on-time of the switch tube in the clamping absorption circuit 40, and determine the hysteresis turn-on dead zone and the advance turn-off dead zone of the switch tube in the clamping absorption circuit 40 relative to the switch tube in the bridge circuit 30;

[0113] Then, the minimum on-time, the delayed turn-on dead zone, and the advanced turn-off dead zone are superimposed to determine the minimum pulse width.

[0114] With the vehicle-mounted DC-DC control circuit of the present application, the controller 10 detects the input voltage across the first capacitor in real time through the voltage detector 20. When it is detected that the voltage value across the first capacitor is between the overvoltage protection value and the undervoltage protection value, all the switch tubes of the bridge circuit 30, all the switch tubes of the rectifier circuit 50, and all the switch tubes of the clamping absorption circuit 40 are in a conductive state. In the dynamic startup process, the present application first performs a capacitor pre-charging stage, and then performs a closed-loop startup stage with restrictions. At the same time, the input voltage across the first capacitor is detected in real time through the voltage detector, and the input overvoltage and undervoltage protection values ​​are corrected cycle by cycle according to the voltage of the input capacitor C1. To a certain extent, it solves the problem of the quality risk of the vehicle-mounted DC-DC caused by the rapid rise or fall of the high-voltage bus voltage of the whole vehicle.

[0115] The present application scheme can effectively avoid the risk of damage to vehicle-mounted DC-DC power devices caused by rapid fluctuations in high voltage. In addition, the present application can control the MOS switch tube stress of the rectifier circuit 50 in the circuit to remain within the required range, thereby improving the working reliability of the vehicle-mounted DC-DC converter.

[0116] Example 2

[0117] This embodiment provides a vehicle-mounted DC-DC control method applied to a vehicle-mounted DC-DC control circuit. For details not disclosed in the control method of this embodiment, please refer to the specific implementation content of the vehicle-mounted DC-DC control circuit in other embodiments.

[0118] Figure 4 The principle flow chart of the vehicle-mounted DC-DC control method according to an embodiment of the present application is shown in FIG.

[0119] like Figure 4 As shown, after receiving the startup command, the startup process first enters the pre-charging stage, then the soft start stage, and then the normal working stage.

[0120] At the same time in these three stages, the input voltage across the first capacitor is detected in real time by the voltage detector, and under-voltage and over-voltage judgment is performed:

[0121] Firstly, the overvoltage protection value and the undervoltage protection value are corrected periodically by the voltage value of the first capacitor.

[0122] Then, when it is monitored that the voltage value on both sides of the first capacitor is between the overvoltage protection value and the undervoltage protection value, the switch tube of the bridge circuit, the switch tube of the rectifier circuit and the switch tube of the clamping absorption circuit are put into a conductive state; otherwise, when it is monitored that the voltage value on both sides of the first capacitor is outside the range of the overvoltage protection value and the undervoltage protection value, the machine is shut down and the current stage of work is stopped.

[0123] Figure 5 A schematic diagram of the steps of the vehicle-mounted DC-DC control method according to an embodiment of the present application is shown in FIG.

[0124] like Figure 5 As shown, see Figure 1 The control method comprises the following steps:

[0125] S1: The startup process of the DC-DC converter enters the pre-charging stage, and the voltage of the third capacitor C3 in the clamping absorption circuit 40 is charged to the first voltage range;

[0126] The calculation formula for the first voltage interval is:

[0127] <( ) / N*2;

[0128] in, is the pre-charge voltage of the third capacitor C3, V is the current input voltage, is the allowable fluctuation value of the input voltage, and N is the transformer turns ratio.

[0129] S2: The startup process of the DC-DC converter enters the soft start stage, and the minimum pulse width of the primary side driving voltage of the DC-DC converter is set; during closed-loop startup, the initial pulse width of the primary side driving voltage starts from the minimum pulse width and limits the sudden change of the pulse width within the threshold;

[0130] S3: Make the DC-DC converter enter the working stage.

[0131] S4: In the pre-charging stage, the soft-start stage and the working stage, the input voltage across the first capacitor is detected in real time by a voltage detector; the overvoltage protection value and the undervoltage protection value are corrected cycle by cycle according to the voltage value of the first capacitor, and when it is monitored that the voltage value across the first capacitor is between the overvoltage protection value and the undervoltage protection value, the switch tube of the bridge circuit, the switch tube of the rectifier circuit and the switch tube of the clamping absorption circuit are put into a conductive state; otherwise, the current work is stopped.

[0132] Figure 6 A schematic diagram of the steps for setting the minimum pulse width of the primary side driving voltage of the DC-DC converter is shown in FIG.

[0133] like Figure 6 As shown, the minimum pulse width of the primary side driving voltage of the DC-DC converter is set in S2 including:

[0134] S21: First, determine the minimum on-time of the switch tube in the clamping absorption circuit 40, and determine the hysteresis turn-on dead zone and the advance turn-off dead zone of the switch tube in the clamping absorption circuit 40 relative to the switch tube in the bridge circuit 30;

[0135] S22: Then, the minimum on-time, the delayed turn-on dead zone, and the advanced turn-off dead zone are superimposed to determine the minimum pulse width.

[0136] The application adopts the minimum pulse width to ensure that C3 can be replenished or discharged in each cycle, so that it can quickly reach the theoretical platform voltage;

[0137] Limiting pulse width mutation within a certain range can effectively prevent startup or dynamic magnetization.

[0138] By adopting the vehicle-mounted DC-DC control method of the present application, during the dynamic startup process, a capacitor pre-charging stage is first performed, followed by a closed-loop startup stage with restrictions. At the same time, the input voltage across the first capacitor is detected in real time by a voltage detector, and the input overvoltage and undervoltage protection values ​​are corrected cycle by cycle according to the voltage of the input capacitor C1.

[0139] The application scheme can effectively avoid the risk of damage to vehicle-mounted DC-DC power devices caused by rapid fluctuations in high voltage. In addition, the application can control the stress of the MOS switch tube of the rectifier circuit in the circuit to be within the required range, thereby improving the working reliability of the vehicle-mounted DC-DC converter.

[0140] Example 3

[0141] This embodiment provides a vehicle-mounted DC-DC control device. For details not disclosed in the vehicle-mounted DC-DC control device of this embodiment, please refer to the specific implementation content of the vehicle-mounted DC-DC control circuit or system in other embodiments.

[0142] Figure 7 Schematic diagram of the structure of a vehicle-mounted DC-DC control device 400 according to an embodiment of the present application is shown in FIG.

[0143] like Figure 7 As shown, the vehicle-mounted DC-DC control device 400 includes: a storage unit 402: used to store executable instructions; and a processing unit 401: used to connect with the storage unit 402 to execute the executable instructions to complete the vehicle-mounted DC-DC control method.

[0144] Those skilled in the art will understand that Figure 4 The foregoing is merely an example of the vehicle-mounted DC-DC control device 400 and does not constitute a limitation on the vehicle-mounted DC-DC control device 400. The vehicle-mounted DC-DC control device 400 may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the vehicle-mounted DC-DC control device 400 may also include input and output devices, network access devices, buses, etc.

[0145] The so-called processing unit 401 (Central Processing Unit, CPU) can also be other general-purpose processors, digital signal processors (Digital Signal Processor, DSP), application-specific integrated circuits (Application Specific Integrated Circuit, ASIC), field-programmable gate arrays (Field-Programmable Gate Array, FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor can be a microprocessor or the processing unit 401 can also be any conventional processor, etc. The processing unit 401 is the control center of the vehicle-mounted DC-DC control device 400, and uses various interfaces and lines to connect various parts of the entire vehicle-mounted DC-DC control device 400.

[0146] The storage unit 402 can be used to store computer-readable instructions. The processing unit 401 implements various functions of the vehicle-mounted DC-DC control device 400 by running or executing the computer-readable instructions or modules stored in the storage unit 402 and calling the data stored in the storage unit 402. The storage unit 402 can mainly include a program storage area and a data storage area, wherein the program storage area can store an operating system, an application required for at least one function (such as a sound playback function, an image playback function, etc.), etc.; the data storage area can store data created according to the use of the vehicle-mounted DC-DC control device 400, etc. In addition, the storage unit 402 can include a hard disk, a memory, a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), at least one disk vehicle-mounted DC-DC control device component, a flash memory device, a read-only vehicle-mounted DC-DC control device (Read-Only Memory, ROM), a random access vehicle-mounted DC-DC control device (Random Access Memory, RAM) or other non-volatile / volatile vehicle-mounted DC-DC control device components.

[0147] If the module integrated in the vehicle-mounted DC-DC control device 400 is implemented in the form of a software function module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present invention implements all or part of the processes in the above-mentioned embodiment method, and can also instruct the relevant hardware to complete it through computer-readable instructions. The computer-readable instructions can be stored in a computer-readable storage medium. When the computer-readable instructions are executed by the processor, the steps of each of the above-mentioned method embodiments can be implemented.

[0148] Example 4

[0149] This embodiment provides an electric vehicle. For details not disclosed in the electric vehicle of this embodiment, please refer to the specific implementation contents of the vehicle-mounted DC-DC control circuit or method in other embodiments.

[0150] Example 5

[0151] This embodiment provides a computer-readable storage medium on which a computer program is stored; the computer program is executed by a processor to implement the vehicle-mounted DC-DC control circuit in other embodiments.

[0152] The memory and storage medium of the embodiment of the present application, the controller is used to correct the voltage value of the first capacitor period by period to obtain the overvoltage protection value and the undervoltage protection value; the input voltage across the first capacitor is detected in real time by the voltage detector, and when the voltage value across the first capacitor is detected to be between the overvoltage protection value and the undervoltage protection value, all the switch tubes of the bridge circuit, all the switch tubes of the rectifier circuit and all the switch tubes of the clamping absorption circuit are turned on; in the dynamic startup process, the capacitor pre-charging stage is first performed, and then the closed-loop startup stage with restrictions is performed. To a certain extent, the problem of the risk of vehicle-mounted DCDC quality caused by the rapid jump or drop of the high-voltage bus voltage of the whole vehicle is solved.

[0153] The present application scheme can effectively avoid the risk of damage to vehicle-mounted DCDC power devices caused by rapid fluctuations in high voltage. In addition, the present application can control the MOS switch tube stress of the rectifier circuit 50 in the circuit to remain within the required range, thereby improving the working reliability of the vehicle-mounted DC-DC converter.

[0154] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0155] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0156] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0157] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process in the computer or other programmable device. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0158] The terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The singular forms "a", "the" and "the" used in the present invention and the appended claims are also intended to include plural forms unless the context clearly indicates other meanings. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0159] It should be understood that although the terms first, second, third, etc. may be used in the present invention to describe various information, these information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present invention, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0160] Although the preferred embodiments of the present application have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0161] Obviously, those skilled in the art can make various changes and modifications to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and their equivalents, the present application is also intended to include these modifications and variations.

Claims

1. A vehicle-mounted DC-DC control circuit, characterized in that: The invention comprises a DC-DC converter, a voltage detector and a controller; the DC-DC converter comprises a first capacitor, a bridge circuit, a first inductor, a transformer, a rectifier circuit, a clamping absorption circuit and a second capacitor connected in sequence; the first capacitor is connected in parallel with the bridge circuit, and the voltage across the first capacitor determines the primary side voltage of the transformer and the secondary side voltage of the transformer; The controller is connected to the voltage detector; the controller is used to control the DC-DC converter to sequentially enter the pre-charging stage, the soft-start stage and the working stage of the startup process; The controller is also used to detect the input voltage at both ends of the first capacitor in real time through a voltage detector during the pre-charging stage, the soft-start stage and the working stage; correct the overvoltage protection value and the undervoltage protection value period by period according to the voltage value of the first capacitor, and when it is monitored that the voltage value at both ends of the first capacitor is between the overvoltage protection value and the undervoltage protection value, make the switch tube of the bridge circuit, the switch tube of the rectifier circuit and the switch tube of the clamping absorption circuit in a conductive state; In the pre-charging stage, the voltage of the third capacitor in the clamping absorption circuit is charged to the first voltage range; In the soft start phase, the minimum pulse width of the primary side driving voltage of the DC-DC converter is set; during closed-loop startup, the initial pulse width of the primary side driving voltage starts from the minimum pulse width and limits the sudden change of the pulse width to within the threshold; Wherein, the bridge circuit is connected to the first inductor and then to the primary winding of the transformer; The bridge circuit includes a first bridge arm and a second bridge arm connected in parallel; both ends of the first bridge arm and the second bridge arm receive the input voltage or output voltage of the primary side of the transformer; the first bridge arm includes a first switch tube and a fourth switch tube, and the second bridge arm includes a third switch tube and a second switch tube; The common node of the first bridge arm is connected to one end of the primary winding of the transformer, and the common node of the second bridge arm is connected to the first inductor and then to the other end of the primary winding of the transformer; Wherein, the rectifier circuit is connected between two ends of the secondary winding of the transformer and ground; the secondary winding of the transformer includes a first secondary winding and a second secondary winding, and the connection point between the first secondary winding and the second secondary winding is a center tap of the transformer; The rectifier circuit includes a first rectifier tube, a second rectifier tube and a second inductor; The two ends of the secondary winding of the transformer are respectively connected to one end of the first rectifier tube and one end of the second rectifier tube, and the other end of the first rectifier tube and the other end of the second rectifier tube are grounded; the center tap of the transformer is connected to the second inductor and then to one end of the second capacitor, and the other end of the second capacitor is grounded; The step of correcting the overvoltage protection value and the undervoltage protection value periodically according to the voltage value of the first capacitor includes: When the input voltage jumps, the equivalent circuit of the DC-DC converter impact path is obtained; According to the equivalent circuit of the DC-DC converter impact path, the allowable fluctuation value of the input voltage is determined The allowable fluctuation value The calculation formula is: ； in, The value of depends on the current carrying capacity of all the switch tubes in the bridge circuit and the clamping absorption circuit; Wherein, L is the sum of the first inductor L1, the transformer primary line inductance and the transformer secondary line inductance converted to the primary side inductance; C is the capacity of the third capacitor C3 converted to the primary side; According to the allowable fluctuation value of the input voltage , correct the overvoltage protection value and undervoltage protection value, and get the overvoltage protection value as V+∆V, and the undervoltage protection value as V-∆V; V is the current input voltage.

2. The vehicle-mounted DC-DC control circuit according to claim 1, characterized in that: The clamping absorption circuit is connected between two ends of the secondary winding of the transformer and ground; the secondary winding of the transformer includes a first secondary winding and a second secondary winding, and the connection point between the first secondary winding and the second secondary winding is a center tap of the transformer; The clamping absorption circuit includes a first clamping switch tube, a second clamping switch tube and a third capacitor; The two ends of the secondary winding of the transformer are respectively connected to one end of the first clamp switch tube and one end of the second clamp switch tube; after the other ends of the first clamp switch tube and the second clamp switch tube are connected, they are connected to the first end of the third capacitor, and the second end of the third capacitor is grounded.

3. The vehicle-mounted DC-DC control circuit according to claim 1, characterized in that: The step of charging the voltage of the third capacitor in the clamping absorption circuit to the first voltage interval includes: The third capacitor is charged by a small duty cycle of the switch tube of the bridge circuit, so that the pre-charge voltage of the third capacitor is within the first voltage range; The calculation formula for the first voltage interval is: <( ) / N*2； in, is the pre-charge voltage of the third capacitor, V is the current input voltage, ∆V is the allowable fluctuation value of the input voltage, and N is the transformer turns ratio.

4. The vehicle-mounted DC-DC control circuit according to claim 1, characterized in that: The step of setting the minimum pulse width of the primary side driving voltage of the DC-DC converter comprises: Determine the minimum on-time of the switch tube in the clamping absorption circuit, and determine the hysteresis turn-on dead zone and the advance turn-off dead zone of the switch tube in the clamping absorption circuit relative to the switch tube in the bridge circuit; The minimum on-time, the delayed turn-on dead zone, and the advanced turn-off dead zone are superimposed to determine the minimum pulse width.

5. A vehicle-mounted DC-DC control method applied to a vehicle-mounted DC-DC control circuit, characterized in that: The vehicle-mounted DC-DC control circuit is a circuit according to any one of claims 1 to 4, comprising a DC-DC converter, a voltage detector and a controller; the DC-DC converter comprises a first capacitor, a bridge circuit, a first inductor, a transformer, a rectifier circuit, a clamping absorption circuit and a second capacitor connected in sequence; the first capacitor is connected in parallel with the bridge circuit, and the voltage across the first capacitor determines the primary side voltage of the transformer and the secondary side voltage of the transformer; The control method comprises the following steps: The startup process of the DC-DC converter enters a pre-charging stage, and the voltage of the third capacitor in the clamping absorption circuit is charged to the first voltage interval; The startup process of the DC-DC converter enters the soft start stage, and the minimum pulse width of the primary side driving voltage of the DC-DC converter is set; during closed-loop startup, the initial pulse width of the primary side driving voltage starts from the minimum pulse width and limits the sudden change of the pulse width to within the threshold; The DC-DC converter enters a working phase; During the pre-charging stage, the soft-start stage and the working stage, the input voltage across the first capacitor is detected in real time by a voltage detector; the overvoltage protection value and the undervoltage protection value are corrected cycle by cycle according to the voltage value of the first capacitor; when it is monitored that the voltage value across the first capacitor is between the overvoltage protection value and the undervoltage protection value, the switch tube of the bridge circuit, the switch tube of the rectifier circuit and the switch tube of the clamping absorption circuit are put into a conductive state; otherwise, the current operation is stopped.

6. A vehicle-mounted DC-DC control device, characterized in that: include: A storage unit for storing executable instructions; as well as A processing unit is used to connect to the memory to execute executable instructions to complete the method as claimed in claim 5.

7. An electric vehicle, characterized in that: The vehicle-mounted DC-DC control circuit comprises the vehicle-mounted DC-DC control circuit according to any one of claims 1 to 4.

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