Control method and system for active short circuit of electric control system of electric vehicle

Abstract

The invention provides a control method and system for active short circuit of an electric control system of an electric vehicle, and the method comprises the steps: when the electric control system breaks down, if the fault is a short-circuit fault, judging whether the fault belongs to an IGBT short-circuit fault only occurring in an upper / lower bridge, and if yes, entering an ASC mode short-circuit state of the bridge where the fault is located; if the fault is the open-circuit fault, judging whether the upper bridge and the lower bridge have the open-circuit fault, and if so, performing the next step; otherwise, entering an ASC mode short-circuit state of the other bridge of the bridge where the open-circuit fault is located; the number of upper bridge open circuits and the number of lower bridge open circuits in the faults are compared, and the ASC mode two-phase short circuit state of the bridge where the small number of open circuit faults are located is entered; and if the number of the upper bridge open-circuit faults is equal to the number of the lower bridge open-circuit faults, selecting one to enter an upper / lower bridge ASC mode two-phase short-circuit state. According to the scheme, the risk of direct conduction of the positive electrode and the negative electrode of the battery possibly caused by a short-circuit fault of the other bridge when a default upper / lower bridge ASC active short circuit is directly entered is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of electric vehicle safety, and in particular to a control method and system for active short circuit of an electric control system of an electric vehicle. Background Art

[0002] In the electronic control system of new energy vehicles, the normal operation of the electronic control system is extremely important. Once the electronic control system fails, the system will be abnormal at the least, and the vehicle will be destroyed and people will die at the worst. And as the lowest-level executive device, the electronic control system is difficult to control and diagnose itself. Therefore, in the event of a motor failure, the electronic control system needs to be actively protected. The two most common active protection measures are SPO (Safety Pulse Off), also known as Freewheeling, and ASC (Active Short Circuit). SPO is implemented by disconnecting all the switch tubes to achieve the separation of the motor and the controller (this isolation is not complete because the body diode has the function of freewheeling); ASC is achieved by short-circuiting the upper bridge or the lower bridge to separate the motor and the controller.

[0003] Generally, when the electronic control system fails, the system will enter Figure 1 The lower bridge three-phase short circuit or Figure 2 The upper bridge three-phase short circuit safety state shown in the figure will enter the open circuit state when the motor speed is low or the reverse electromotive force is less than the bus voltage, such as Figure 3 The three-phase circuit is shown as open. Among them, when the three phases of the lower bridge are short-circuited, the gate levels of U_LS, V_LS and W_LS are powered on, the IGBT is turned on, the gate levels of U_HS, V_HS and W_HS are powered off, and the IGBT is not turned on; when U_LS, V_LS and W_LS are turned on, the three-phase lines of the motor are short-circuited together. When the three phases of the upper bridge are short-circuited, the gate levels of U_HS, V_HS and W_HS are powered on, the IGBT is turned on, the gate levels of U_LS, V_LS and W_LS are powered off, and the IGBT is not turned on; when U_HS, V_HS and W_HS are turned on, the three-phase lines of the motor are short-circuited together. When the three phases are open, the upper bridge U_HS, V_HS, W_HS and the lower bridge U_LS, V_LS, W_LS are powered off at the same time, and the IGBT is not turned on.

[0004] The above-mentioned method of controlling the electronic control system to enter a short-circuit or open-circuit safety state has the following disadvantages: (1) When a motor and a motor controller fail, the lower bridge short-circuit safety state is entered by default. If a phase of the upper bridge is short-circuited U_HS, V_HS, or W_HS, or two phases of the upper bridge are short-circuited U_HS, V_HS, or W_HS, or three phases of the upper bridge are short-circuited U_HS, V_HS, and W_HS, there may be a risk of direct conduction of the positive and negative poles of the battery; (2) When a motor and a motor controller fail, the lower bridge short-circuit safety state is entered by default. If an open-circuit fault occurs simultaneously on the upper and lower bridges of a phase U, V, or W, resulting in the electronic control being unable to fully enter the lower bridge or the upper bridge active short circuit (Active Short Circuit, referred to as ASC), if the electronic control system is controlled to enter the open-circuit state at this time, there may be a risk of excessive reverse electromotive force. Summary of the invention

[0005] Based on the above-mentioned problems existing in the prior art, the present invention aims to provide a control method and system for active short circuit of an electric vehicle electronic control system, so as to solve the technical problem in the prior art that when a vehicle electronic control system fails, directly entering the default upper bridge or lower bridge short circuit state based on ASC will cause safety risks.

[0006] The present invention provides a control method for active short circuit of an electric vehicle electric control system, which comprises the following steps:

[0007] When the motor fails, determine the type of fault in the electronic control system;

[0008] If a short-circuit fault occurs, the ASC mode of the bridge where the fault occurs will enter the safe short-circuit state;

[0009] If an open circuit fault occurs, determine whether both the upper bridge and the lower bridge have open circuit faults. If so, proceed to the next step; otherwise, enter the ASC mode safety short circuit state of the other bridge where the open circuit fault occurs;

[0010] Compare the number of open circuit faults on the upper bridge and the number of open circuit faults on the lower bridge in this fault, and enter the ASC mode two-phase safe short-circuit state of the bridge with the smaller number of open circuit faults; if the number of open circuit faults on the upper bridge is equal to the number of open circuit faults on the lower bridge, select one of the upper / lower bridges to enter the ASC mode two-phase safe short-circuit state.

[0011] According to an embodiment of the present invention, when a fault occurs, the priority of processing a short circuit fault is higher than the priority of processing an open circuit fault.

[0012] According to one embodiment of the present invention, the control method for active short circuit of the electric vehicle electronic control system is applicable to any one of the following three fault conditions: an IGBT short circuit fault only occurs in the upper / lower bridge, an open circuit fault only occurs in the upper / lower bridge, or an open circuit fault occurs in both the upper bridge and the lower bridge, and an open circuit fault occurs in only one phase of at least one bridge.

[0013] According to an embodiment of the present invention, the upper / lower bridge entering the ASC mode two-phase safety short-circuit state is limited only when an open-circuit fault occurs in one phase of the bridge.

[0014] According to an embodiment of the present invention, the fault situation in which the number of upper bridge open circuit faults is equal to the number of lower bridge open circuit faults is: both the upper bridge and the lower bridge of a phase have open circuit faults, or the upper bridge of a phase has an open circuit fault and the lower bridge of another phase has an open circuit fault.

[0015] The present invention also provides a control system for active short circuit of an electric vehicle electric control system, which comprises a judgment module and a comparison module. The judgment module is used to judge the type of fault in the electric control system when a motor fails, and enter the ASC mode safety short circuit state of the bridge where the fault occurs when a short circuit fault occurs; the comparison module is started when an open circuit fault occurs on both the upper bridge and the lower bridge, and when an open circuit fault occurs on one of the upper bridge and the lower bridge, the ASC mode safety short circuit state of the other bridge where the open circuit fault occurs is entered;

[0016] The comparison module is used to compare the number of open circuit faults in the upper bridge and the number of open circuit faults in the lower bridge in the fault when open circuit faults occur on both the upper bridge and the lower bridge of the electronic control system, and enter the ASC mode two-phase safe short-circuit state of the bridge where the open circuit fault number is smaller; and when the number of open circuit faults in the upper bridge is equal to the number of open circuit faults in the lower bridge, choose to enter the ASC mode two-phase safe short-circuit state of the upper / lower bridge.

[0017] The present invention provides a control method and system for active short circuit of an electric vehicle electric control system, which has the following beneficial effects:

[0018] (1) When a motor fails, this solution first determines the type of fault in the electronic control system, and selectively enters the upper / lower bridge ASC mode based on the type and location of the IGBT short-circuit or open-circuit fault, thereby avoiding the risk of direct conduction of the positive and negative electrodes of the battery caused by a short-circuit fault in another bridge when the default upper / lower bridge ASC is directly entered into the active short circuit in the prior art;

[0019] (2) When an open circuit fault occurs, the system selectively enters the ASC mode two-phase safety short circuit state or the ASC mode (three-phase) safety short circuit state according to the upper bridge and lower bridge open circuit fault conditions (including the fault location and the number of faults). This solves the problem in the prior art that when an open circuit fault occurs in the electronic control system, the system cannot fully enter the upper bridge or lower bridge ASC and directly enters the open circuit state, which may cause the risk of excessive reverse electromotive force. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 It is a schematic diagram of the electric control system entering the safe state of the lower bridge three-phase short circuit in the prior art;

[0022] Figure 2 It is a schematic diagram of the electric control system entering the safe state of the upper bridge three-phase short circuit in the prior art;

[0023] Figure 3 It is a schematic diagram of the electric control system entering a safe state of three-phase open circuit in the prior art;

[0024] Figure 4 It is a flow chart of a control method for active short circuit of an electric control system of an electric vehicle provided by an embodiment of the present invention;

[0025] Figure 5 The present invention provides a circuit diagram of a control system for active short circuit of an electric vehicle electric control system. DETAILED DESCRIPTION

[0026] The following descriptions of the embodiments refer to the attached drawings to illustrate specific embodiments in which the present invention can be implemented.

[0027] The present invention provides a control system for active short circuit of an electric control system of an electric vehicle, which comprises a judgment module and a comparison module. The judgment module is used to judge the type of fault in the electric control system when a motor fails, and enter the ASC mode safety short circuit state of the bridge where the fault occurs when a short circuit fault occurs; the comparison module is started when an open circuit fault occurs in both the upper bridge and the lower bridge, and when an open circuit fault occurs in one of the upper bridge and the lower bridge, the ASC mode safety short circuit state of the other bridge where the open circuit fault occurs is entered;

[0028] The comparison module is used to compare the number of open circuit faults in the upper bridge and the number of open circuit faults in the lower bridge in the fault when open circuit faults occur on both the upper bridge and the lower bridge of the electronic control system, and enter the ASC mode two-phase safe short-circuit state of the bridge where the open circuit fault number is smaller; and when the number of open circuit faults in the upper bridge is equal to the number of open circuit faults in the lower bridge, choose to enter the ASC mode two-phase safe short-circuit state of the upper / lower bridge.

[0029] The present invention also provides a control method for active short circuit of electric vehicle electric control system, which is implemented based on the control system of active short circuit of electric vehicle electric control system, and its flow chart is as follows: Figure 4 As shown, the following steps are included:

[0030] When the motor fails, determine the type of fault in the electronic control system;

[0031] If a short-circuit fault occurs, the ASC mode of the bridge where the fault occurs will enter the safe short-circuit state;

[0032] If an open circuit fault occurs, determine whether both the upper bridge and the lower bridge have open circuit faults. If so, proceed to the next step; otherwise, enter the ASC mode safety short circuit state of the other bridge where the open circuit fault occurs;

[0033] Compare the number of open circuit faults on the upper bridge and the number of open circuit faults on the lower bridge in this fault, and enter the ASC mode two-phase safe short-circuit state of the bridge with the smaller number of open circuit faults; if the number of open circuit faults on the upper bridge is equal to the number of open circuit faults on the lower bridge, select one of the upper / lower bridges to enter the ASC mode two-phase safe short-circuit state.

[0034] According to one embodiment of the present invention, the upper / lower bridge enters the ASC mode two-phase safe short-circuit state only when an open circuit fault occurs in one phase of the bridge. It is not difficult to understand that the upper / lower bridge enters the ASC mode two-phase safe short-circuit state only when an open circuit fault occurs in one phase of the bridge, which means: the prerequisite for the upper / lower bridge to enter the ASC mode two-phase safe short-circuit state is that only one phase of the upper / lower bridge has an open circuit fault. For example, when the U phase of the upper bridge has an open circuit fault, the upper bridge can enter the ASC mode two-phase (V phase and W phase) safe short-circuit state; and when the V phase of the lower bridge has an open circuit fault, the lower bridge can enter the ASC mode two-phase (U phase and W phase) safe short-circuit state.

[0035] According to one embodiment of the present invention, the fault situation in which the number of upper bridge open circuit faults is equal to the number of lower bridge open circuit faults is: open circuit faults occur in both the upper bridge and the lower bridge of a phase (for example, open circuit faults occur in both the upper bridge and the lower bridge of the U phase), or an open circuit fault occurs in the upper bridge of one phase and an open circuit fault occurs in the lower bridge of another phase (for example, an open circuit fault occurs in the upper bridge of the U phase and an open circuit fault occurs in the lower bridge of the V phase).

[0036] like Figure 5The circuit diagram of the automobile electronic control system in the embodiment of the present invention is shown, and from left to right are a DC power supply, a supporting capacitor, a three-phase full-bridge inverter module for converting DC to AC, and a motor for driving the vehicle. The three-phase full-bridge inverter module includes a three-phase upper bridge IGBT power device and a three-phase lower bridge IGBT power device. Each phase of the three-phase upper bridge IGBT power device is respectively connected to each phase of the three-phase lower bridge IGBT power device, and the three-phase upper bridge IGBT power device and the three-phase lower bridge IGBT power device are respectively electrically connected to the three phases of the motor. Among them, the three phases of the three-phase full-bridge inverter module include U, V, and W phases, and each phase includes an upper bridge and a lower bridge. Therefore, there can be up to 6 locations where faults may occur, namely, U-phase upper bridge, V-phase upper bridge, W-phase upper bridge, U-phase lower bridge, V-phase lower bridge, and W-phase lower bridge. In actual situations, the number of locations where faults may occur can be 6, 5, 4, 3, 2, and 1. Accordingly, the number of situations for each number of faults is respectively So the total number of failures is: Since there are two types of fault conditions at each location, short circuit or open circuit (break), the total number of short circuit or break fault conditions that actually occur is: It can be seen that there are many types of actual fault conditions in automotive electronic control systems.

[0037] In view of the large number of actual fault conditions, the fault conditions can be divided into general faults and serious faults. Among them, serious faults refer to fault conditions that do not meet the requirements of entering the two-phase safe short-circuit state of the ASC mode and the ASC mode (three-phase) safe short-circuit state, such as two-phase circuit breakage of the upper bridge and two-phase circuit breakage of the lower bridge, or simultaneous circuit breakage of the upper and lower bridges of one phase, circuit breakage of the upper bridge of one of the other two phases, circuit breakage of the lower bridge of the last phase, or simultaneous circuit breakage of the upper and lower bridges of two phases, etc. In serious cases, since the electric control system of the electric vehicle is in an out-of-control state at this time, it is not within the protection scope of this solution (in fact, the ASC active short circuit in the prior art cannot be used for Handling situations where the electric control system of electric vehicles is in a serious fault); general faults refer to fault conditions that meet the requirements of entering the ASC mode two-phase safe short-circuit state and the ASC mode (three-phase) safe short-circuit state in this solution. Specifically, general faults include the following situations: (1) IGBT short-circuit faults that occur only in the upper / lower bridge; (2) Open-circuit faults that occur only in the upper / lower bridge; (3) When open-circuit faults occur in both the upper and lower bridges, at least one of the bridges has an open-circuit fault in only one phase, for example, the upper bridge U and V phases are open, and the lower bridge U phase is open, or the upper bridge U, V, and W phases are open, and the lower bridge W phase is open, or the upper bridge V and W phases are open, and the lower bridge V phase is open.

[0038] Furthermore, in actual situations, open circuit faults and short circuit faults may occur simultaneously in the vehicle, that is, when a fault occurs, there are both short circuit faults and open circuit faults, and the fault may occur at any position, that is, U-phase upper bridge, V-phase upper bridge, W-phase upper bridge, U-phase lower bridge, V-phase lower bridge, W-phase lower bridge, a total of 6 positions, and when a short circuit fault occurs, this scheme enters the ASC mode safety short circuit state of the bridge where the fault occurs; when an open circuit fault occurs, it enters the ASC mode safety short circuit state of the other bridge where the open circuit fault occurs; in order to ensure that the electronic control system can be shut down normally when a fault occurs, for example, when a short circuit fault and an open circuit fault occur simultaneously on the upper bridge , while no fault occurs in the lower bridge, for example, a short circuit occurs in the upper bridge IGBT of phase U and an open circuit occurs in the upper bridge IGBT of phase V. At this time, the upper bridge ASC mode safety short circuit state can be entered normally according to the processing logic of the short circuit fault. However, if the lower bridge ASC mode safety short circuit state is entered according to the processing logic of the open circuit fault, the upper bridge IGBT and the lower bridge IGBT of phase U will be short-circuited at the same time, which may cause the risk of direct conduction of the positive and negative electrodes of the battery. Therefore, in this solution, it is set that when a fault occurs, the priority of handling the short circuit fault is higher than the priority of handling the open circuit fault, that is, the shutdown processing of the electronic control system is performed preferentially according to the processing logic of the short circuit fault.

[0039] In summary, the present invention provides a control method and system for active short circuit of an electric vehicle electric control system. When a motor fails, the fault type of the electric control system is first determined, and the upper / lower bridge ASC mode is selectively entered based on the type of IGBT short circuit or open circuit fault and the fault location, thereby avoiding the risk of direct conduction of the positive and negative electrodes of the battery due to a short circuit fault of another bridge when the default upper / lower bridge ASC is directly entered into the active short circuit in the prior art; at the same time, when an open circuit fault occurs, the ASC mode is selectively entered based on the upper and lower bridge open circuit fault conditions (including the fault location and number). The two-phase safe short-circuit state or the ASC mode (three-phase) safe short-circuit state solves the problem in the prior art that when an open-circuit fault occurs in the electronic control system, the electronic control system cannot fully enter the upper bridge or lower bridge ASC and directly enters the open-circuit state, which may cause excessive reverse electromotive force (the rotation of the motor rotor will generate reverse electromotive force, and the higher the speed, the greater the reverse electromotive force. When the reverse electromotive force is too large, the freewheeling diode of the IGBT is turned on, and the reverse electromotive force flows from the motor through the freewheeling diode into the power supply, causing current backflow, which is equivalent to charging the capacitor. If charged for a long time, the capacitor voltage is too high, and there is a risk of capacitor breakdown).

[0040] It should be noted that although the present invention is disclosed as above by specific embodiments, the above embodiments are not intended to limit the present invention. Ordinary technicians in this field can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined in the claims.

Claims

1. A control method for active short circuit of an electric vehicle electric control system, characterized in that: The following steps are involved: When the motor fails, determine the type of fault in the electronic control system; If a short-circuit fault occurs, the ASC mode of the bridge where the fault occurs will enter the safe short-circuit state; If an open circuit fault occurs, determine whether both the upper bridge and the lower bridge have open circuit faults. If so, proceed to the next step; otherwise, enter the ASC mode safety short circuit state of the other bridge where the open circuit fault occurs; Compare the number of open circuit faults of the upper bridge and the number of open circuit faults of the lower bridge in the fault, and enter the ASC mode two-phase safe short circuit state of the bridge where the number of open circuit faults is smaller; If the number of upper bridge open circuit faults is equal to the number of lower bridge open circuit faults, one of the upper / lower bridges will enter the ASC mode two-phase safety short-circuit state.

2. The control method for active short circuit of electric vehicle electronic control system according to claim 1, characterized in that: When a fault occurs, the priority of handling a short circuit fault is higher than that of an open circuit fault.

3. The control method for active short circuit of electric vehicle electronic control system according to claim 1, characterized in that: The control method for active short circuit of the electric vehicle electronic control system is applicable to any one of the following three fault conditions: an IGBT short circuit fault only occurs in the upper / lower bridge, an open circuit fault only occurs in the upper / lower bridge, or an open circuit fault occurs in both the upper bridge and the lower bridge, and an open circuit fault occurs in only one phase of at least one bridge.

4. The control method for active short circuit of electric vehicle electronic control system according to claim 1, characterized in that: The upper / lower bridge enters the ASC mode two-phase safe short-circuit state only when an open circuit fault occurs in one phase of the bridge.

5. The control method for active short circuit of electric vehicle electronic control system according to claim 1, characterized in that: The fault situations where the number of upper bridge open circuit faults is equal to the number of lower bridge open circuit faults are: open circuit faults occur in both the upper bridge and the lower bridge of a phase, or an open circuit fault occurs in the upper bridge of a phase and an open circuit fault occurs in the lower bridge of another phase.

6. A control system for active short circuit of electric vehicle electronic control system, characterized in that: It includes a judgment module and a comparison module. The judgment module is used to judge the fault type of the electric control system when the motor fails, and enter the ASC mode safety short-circuit state of the bridge where the fault occurs when a short-circuit fault occurs; the comparison module is started when an open-circuit fault occurs on both the upper bridge and the lower bridge, and when an open-circuit fault occurs on one of the upper bridge and the lower bridge, the ASC mode safety short-circuit state of the other bridge where the open-circuit fault occurs is entered; The comparison module is used to compare the number of open circuit faults of the upper bridge and the number of open circuit faults of the lower bridge in the fault when open circuit faults occur on both the upper bridge and the lower bridge of the electric control system, and enter the ASC mode two-phase safe short circuit state of the bridge where the number of open circuit faults is smaller; When the number of upper bridge open circuit faults is equal to the number of lower bridge open circuit faults, one of the upper / lower bridges is selected to enter the ASC mode two-phase safety short-circuit state.

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