Safe turn-off method of new energy automobile motor controller

Abstract

The invention relates to a safe turn-off method for a motor controller of a new energy automobile, and the safe turn-off control steps are as follows: S1, when an MCU detects an emergency braking demand sent by a fault matrix, the MCU judges whether the rotating speed of a motor is greater than a preset value, and if yes, the step S2 is carried out; if not, performing the step S3; s2, an SPO control mode is started, and after preset time is delayed, the step S4 is executed; s3, starting an SPO control mode, judging whether the bus voltage is overvoltage or not, if yes, executing the step S4, and if not, executing the step S3; if not, the step S5 is carried out; s4, starting an ASC control mode, judging whether the three-phase current is over-current or not, if so, returning to the step S3, and if not, returning to the step S4; if not, the step S5 is carried out; s5, judging that the bus voltage reaches the preset value, the motor rotating speed reaches the bottom preset value, reporting the state of the controller to the VCU, and ending the control; according to the method, in the system fault state, the active short circuit (ASC) and passive follow current (SPO) working modes can be intelligently decided, and the safety of the electric drive system is guaranteed.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy vehicle drive motor control, and in particular relates to a safe shutdown method for a new energy vehicle motor controller. Background Art

[0002] The electric drive system is the "heart" of new energy vehicles. The safe operation of the electric drive system is the guarantee of safe driving of the vehicle. Once the electric drive system fails, the consequences will be disastrous. As an actuator in the electric drive system, the motor is difficult to control and diagnose itself. Therefore, in the event of a motor failure, the electric drive system needs to enter a safe state to protect the safety of the electric drive system. The common way is to let the system enter ASC (Active Short Circuit) or SPO (Safety Pulse Off).

[0003] ASC protects the electric drive system by controlling the power module of the controller to close the three-phase upper bridge and disconnect the lower bridge, or to close the three-phase lower bridge and disconnect the upper bridge, so that the three-phase electricity of the motor is short-circuited together. However, in the active short-circuit (ASC) mode, the three-phase lines of the motor are short-circuited, and a transient large current is generated in the motor winding, causing the motor winding temperature to rise rapidly, increasing the risk of motor demagnetization.

[0004] SPO disconnects the motor and controller by disconnecting all six switches of the inverter bridge. In this mode, the energy on the motor side can only be passively rectified by the reverse diode on the inverter bridge. If the maximum value of the back EMF does not exceed 1 / 2Vdc, the back EMF cannot turn on the diode, and the motor will idle for a long time and cannot enter a safe state1. However, when the motor is running at high speed, if the SPO operation is performed, the motor is in a weak magnetic state, and the disappearance of the d-axis current will cause the d-axis magnetic field to increase, generating a higher back EMF. After the back EMF is passively rectified by the diode, the voltage may exceed the battery voltage, causing the DC-Link to charge, the bus voltage to increase, and the risk of controller failure to increase1.

[0005] In summary, both the ASC and SPO modes have certain defects when used, and they need to be handled with caution in motor control applications to avoid possible voltage increases and system risks. The existing motor control systems are in urgent need of a motor control method that can intelligently select appropriate protection measures according to actual working conditions (i.e., can reasonably select the corresponding ASC or SPO mode). Summary of the invention

[0006] In order to solve the above technical problems, the purpose of the present invention is to provide a safe shutdown method for a motor controller of a new energy vehicle, which achieves the safe shutdown logic of the motor controller through intelligent decision-making active short circuit (ASC) and passive freewheeling (SPO) working modes.

[0007] In order to achieve the above-mentioned invention object, the present invention adopts the following technical solutions:

[0008] A safe shutdown method for a new energy vehicle motor controller, the safe shutdown control steps are as follows:

[0009] S1. When the MCU detects the emergency braking demand sent from the fault matrix, the MCU determines whether the motor speed is greater than the preset value. If so, proceed to step S2; if not, proceed to step S3;

[0010] S2, start the SPO control mode, and after a preset delay, enter step S4;

[0011] S3, start the SPO control mode, and determine whether the bus voltage is overvoltage, if so, proceed to step S4; if not, proceed to step S5;

[0012] S4, start the ASC control mode, and determine whether the three-phase current is overcurrent, if so, return to step S3; if not, proceed to step S5;

[0013] S5: Determine that the bus voltage reaches the preset value, the motor speed reaches the preset value, the controller status is reported to the VCU, and the control ends;

[0014] The switching between the SPO control mode and the ASC control mode is performed by using a pre-safety shutdown control circuit formed by a combination of multiple AND gates, OR gates, and NOT gates.

[0015] As a preferred solution: the pre-safety shutdown control circuit includes an AND gate A, an AND gate C, an AND gate D, an OR gate B, an OR gate F and an NOT gate E, the two input ends of the AND gate A are respectively connected to the SPO port of the MCU and the MCU fault port, the two input ends of the AND gate C are respectively connected to the output end of the AND gate A and the PWM_U / V / W_BOT port of the MCU; the two input ends of the AND gate D are respectively connected to the output end of the AND gate A and the PWM_U / V / W_TOP port of the MCU, and the output end of the AND gate D is connected to the CTRL_TOP_UVW port of the IGBT driver; the two input ends of the OR gate B are respectively connected to the SPO port and the ASC port of the MCU, and the output end of the OR gate B is connected to the input end of the NOT gate E, the two input ends of the OR gate F are respectively connected to the output ends of the AND gate C and the NOT gate E, and the output end of the OR gate F is connected to the IGBT driver.

[0016] As a preferred solution: in step S1, the motor speed information is obtained by parsing the three-phase current, and the specific steps are as follows:

[0017] The three-phase current is collected and the current peak is detected to estimate the current frequency. The motor speed is then estimated using the phase current frequency. Motor speed = phase current frequency / number of motor pole pairs.

[0018] As a preferred solution: the bus voltage overvoltage judgment in step S3 is performed by a voltage comparator.

[0019] As a preferred solution: the judgment of the three-phase current overcurrent in step S4 is performed by a three-phase current sensor and a current comparator.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The method of the present invention collects system status (rotation speed, current, voltage) and can intelligently decide on active short circuit (ASC) and passive freewheeling (SPO) working modes under a system fault state, thereby ensuring the safety of the electric drive system under a fault state; at the same time, through the intelligent decision-making of active short circuit (ASC) and passive freewheeling (SPO) working modes, it can not only realize the function of limiting excessive phase current, thereby preventing demagnetization faults of the motor; it can also realize the function of limiting excessive back electromotive force voltage, thereby preventing faults of components such as motor controller LINK capacitors, and improving the stability of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings in the specification, which constitute a part of the present application, are used to provide a further understanding 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 a limitation on the present application.

[0023] Figure 1 It is a schematic diagram of the hardware framework of the method of the present invention;

[0024] Figure 2 It is a structural schematic diagram of the front safety shutdown control circuit of the method of the present invention;

[0025] Figure 3 It is a control logic flow chart of the method of the present invention. DETAILED DESCRIPTION

[0026] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0027] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0028] In addition, in the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0029] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more, unless otherwise clearly specified.

[0030] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0031] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0032] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0033] like Figures 1 to 3 As shown, a safe shutdown method for a new energy vehicle motor controller, the safe shutdown control steps are as follows:

[0034] S1. When the MCU detects the emergency braking demand sent from the fault matrix, the MCU determines whether the motor speed is greater than the preset value. If so, proceed to step S2; if not, proceed to step S3;

[0035] S2, start the SPO control mode, and after a preset delay, enter step S4;

[0036] S3, start the SPO control mode, and determine whether the bus voltage is overvoltage, if so, proceed to step S4; if not, proceed to step S5;

[0037] S4, start the ASC control mode, and determine whether the three-phase current is overcurrent, if so, return to step S3; if not, proceed to step S5;

[0038] S5: Determine that the bus voltage reaches the preset value, the motor speed reaches the preset value, the controller status is reported to the VCU, and the control ends;

[0039] The switching between the SPO control mode and the ASC control mode is performed by using a pre-safety shutdown control circuit formed by a combination of multiple AND gates, OR gates, and NOT gates.

[0040] The method of the present invention achieves the safe shutdown logic of the motor controller by real-time monitoring of phase current, bus voltage, rotation speed and other states, and intelligently deciding active short circuit (ASC) and passive freewheeling (SPO) working modes; and through phase current and voltage judgment logic, the voltage and current states are judged in real time. If an overcurrent is detected in the active short circuit working mode, the passive freewheeling working mode can be switched; if an overvoltage is detected in the passive freewheeling working mode, the active short circuit working mode can be switched.

[0041] As a preferred solution: the pre-safety shutdown control circuit includes an AND gate A, an AND gate C, an AND gate D, an OR gate B, an OR gate F and an NOT gate E, the two input ends of the AND gate A are respectively connected to the SPO port of the MCU and the MCU fault port, the two input ends of the AND gate C are respectively connected to the output end of the AND gate A and the PWM_U / V / W_BOT port of the MCU; the two input ends of the AND gate D are respectively connected to the output end of the AND gate A and the PWM_U / V / W_TOP port of the MCU, and the output end of the AND gate D is connected to the CTRL_TOP_UVW port of the IGBT driver; the two input ends of the OR gate B are respectively connected to the SPO port and the ASC port of the MCU, and the output end of the OR gate B is connected to the input end of the NOT gate E, the two input ends of the OR gate F are respectively connected to the output ends of the AND gate C and the NOT gate E, and the output end of the OR gate F is connected to the IGBT driver.

[0042] The front safety shutdown control circuit can ensure that the upper and lower bridge arms will not be in a short-circuit state. The SPO / ASC value-added table of the circuit is as follows:

[0043]

[0044] The value-added table shows that the ASC working mode can only be entered when both the ASC and SPO control signals are activated. This avoids the possibility of short circuits between the upper and lower bridge arms during the ASC\SPO working mode switching process at the hardware level.

[0045] As a preferred solution: in step S1, the motor speed information is parsed through the three-phase current, and the specific steps are as follows: collect the three-phase current, detect the peak value, and estimate the motor speed using the phase current frequency, where the motor speed = phase current frequency / number of motor pole pairs. The motor speed information is parsed through the three-phase current, and is used as a basis for determining the speed in the event of a resolver failure; a safety channel redundancy design is achieved.

[0046] As a preferred solution: the bus voltage overvoltage judgment in step S3 is performed by a voltage comparator. The three-phase current overcurrent judgment in step S4 is performed by a three-phase current sensor and a current comparator. The overcurrent, overvoltage, speed and other parameters in the method of the present invention are all judged by hardware logic, which improves the system response speed. The active short circuit and passive freewheeling switching are realized by a logic circuit, which improves the system response speed; the entire system safety fault processing time is short, which improves the reliability of the system.

[0047] The method of the present invention collects system status (rotation speed, current, voltage) and can intelligently decide on active short circuit (ASC) and passive freewheeling (SPO) working modes under a system fault state, thereby ensuring the safety of the electric drive system under a fault state; at the same time, through the intelligent decision-making of active short circuit (ASC) and passive freewheeling (SPO) working modes, it can not only realize the function of limiting excessive phase current, thereby preventing demagnetization faults of the motor; it can also realize the function of limiting excessive back electromotive force voltage, thereby preventing faults of components such as motor controller LINK capacitors, and improving the stability of the system.

[0048] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0049] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. Ordinary technicians in the field can change, modify, replace and modify the above embodiments within the scope of the present invention without departing from the principles and purpose of the present invention. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A safe shutdown method for a new energy vehicle motor controller, characterized in that: The safety shutdown control steps are as follows: S1. When the MCU detects the emergency braking demand sent from the fault matrix, the MCU determines whether the motor speed is greater than the preset value. If so, proceed to step S2; if not, proceed to step S3; S2, start the SPO control mode, and after a preset delay, enter step S4; S3, start the SPO control mode, and determine whether the bus voltage is overvoltage, if so, proceed to step S4; if not, proceed to step S5; S4, start the ASC control mode, and determine whether the three-phase current is overcurrent, if so, return to step S3; if not, proceed to step S5; S5: Determine that the bus voltage reaches the preset value, the motor speed reaches the preset value, the controller status is reported to the VCU, and the control ends; The switching between the SPO control mode and the ASC control mode is performed by using a pre-safety shutdown control circuit formed by a combination of multiple AND gates, OR gates, and NOT gates.

2. A safe shutdown method for a new energy vehicle motor controller according to claim 1, characterized in that: The front safety shutdown control circuit includes an AND gate A, an AND gate C, an AND gate D, an OR gate B, an OR gate F and an NOT gate E. The two input ends of the AND gate A are respectively connected to the SPO port of the MCU and the MCU fault port, and the two input ends of the AND gate C are respectively connected to the output end of the AND gate A and the PWM_U / V / W_BOT port of the MCU; the two input ends of the AND gate D are respectively connected to the output end of the AND gate A and the PWM_U / V / W_TOP port of the MCU, and the output end of the AND gate D is connected to the CTRL_TOP_UVW port of the IGBT driver; the two input ends of the OR gate B are respectively connected to the SPO port and the ASC port of the MCU, and the output end of the OR gate B is connected to the input end of the NOT gate E, the two input ends of the OR gate F are respectively connected to the output ends of the AND gate C and the NOT gate E, and the output end of the OR gate F is connected to the IGBT driver.

3. The method for safely shutting down a motor controller of a new energy vehicle according to claim 1, characterized in that: In step S1, the motor speed information is obtained by parsing the three-phase current, and the specific steps are as follows: The three-phase current is collected and the current peak is detected to estimate the current frequency. The motor speed is then estimated using the phase current frequency. Motor speed = phase current frequency / number of motor pole pairs.

4. The method for safely shutting down a motor controller of a new energy vehicle according to claim 1, characterized in that: The bus voltage overvoltage judgment in step S3 is performed by a voltage comparator.

5. The method for safely shutting down a motor controller of a new energy vehicle according to claim 1, characterized in that: In step S4, the judgment of whether the three-phase current is overcurrent is performed by a three-phase current sensor and a current comparator.

Images