A method for electric vehicle motor mode conversion and torque limitation

Abstract

The present invention relates to a method for converting and limiting the motor mode of an electric vehicle. The method comprises determining the motor mode of the electric vehicle based on the vehicle state and vehicle information; obtaining a torque limit for the electric vehicle based on the motor mode, wherein the vehicle state includes a low-voltage state, a high-voltage drivable state, and a charging state; the vehicle information includes the current gear, required torque, maximum battery discharge / charge power, motor peak torque, current vehicle speed, fault type, motor speed, DC-DC power, air conditioning power, PTC power, and special operating conditions, wherein the fault type includes a speed limit fault, a power limit fault, a power output prohibition fault, and a low-voltage fault; and the special operating conditions include cruise control and anti-slope conditions. The method for converting and limiting the motor mode of an electric vehicle provided by the present invention can respond to torque demands in a timely manner, thereby improving the stability and comfort of new energy vehicles.

Description

Technical Field

[0001] The present invention relates to the technical field of electric vehicles and provides a method for mode conversion and torque limitation of an electric vehicle motor. Background Art

[0002] After years of development, new energy electric vehicle technology has evolved into the following categories: pure electric vehicles, hybrid electric vehicles, and plug-in hybrid electric vehicles. Pure electric vehicles are currently the primary driver of development. Currently, electric vehicle motor modes and torque limiting methods are relatively crude, unable to respond promptly to torque demands, resulting in poor stability and comfort. This clearly fails to meet the drive system control requirements of the pure electric vehicle market for comfort and handling stability.

[0003] Based on this, the present invention provides a method for electric vehicle motor mode conversion and torque limitation. Summary of the Invention

[0004] In response to the above problems, the present invention provides a method for electric vehicle motor mode conversion and torque limitation.

[0005] The first object of the present invention is to provide a torque limiting method for an electric vehicle. The torque limiting method comprises:

[0006] Determine the motor mode of the electric vehicle based on the vehicle status and vehicle information, wherein the vehicle status includes a low-voltage state, a high-voltage drivable state, and a charging state; the vehicle information includes the current gear, required torque, maximum battery discharge / charge power, motor peak torque, current vehicle speed, fault type, motor speed, DC-DC power, air conditioning power, PTC power, and special operating conditions, wherein the fault type includes a speed limit fault, a power limit fault, a power output prohibition fault, and a high-voltage fault; and the special operating conditions include cruise control and hill-slip prevention conditions;

[0007] Based on the motor mode, the electric vehicle torque limit is obtained.

[0008] Furthermore, the determining of the motor mode of the electric vehicle based on the vehicle state and vehicle information includes:

[0009] When the vehicle state is a low voltage state or a charging state, the motor mode is a pulse width modulation off mode, i.e., a PWM OFF mode;

[0010] When the vehicle state is a high-voltage drivable state, the motor mode is determined based on whether the electric vehicle has any fault.

[0011] Furthermore, the motor mode is determined based on whether a fault occurs in the electric vehicle, including:

[0012] The electric vehicle has a fault, and the motor mode is a fault mode;

[0013] If no fault occurs in the electric vehicle, the motor mode is determined based on whether any special operating conditions occur in the electric vehicle.

[0014] Furthermore, the motor mode is determined based on whether the electric vehicle has a special operating condition, including:

[0015] The electric vehicle has a special operating condition, and the motor mode is a speed mode;

[0016] If no special operating conditions occur in the electric vehicle, the motor mode is determined based on the required torque and the current gear.

[0017] Furthermore, determining the motor mode according to the required torque and the current gear position includes:

[0018] When the required torque is zero, the motor mode is zero torque mode;

[0019] The required torque is positive, the current gear is the forward gear, and the motor mode is the forward drive mode (i.e., D gear drive);

[0020] The required torque is negative, the current gear is reverse gear, and the motor mode is reverse drive mode (i.e., R gear drive);

[0021] The required torque is negative, the current gear is the forward gear, and the motor mode is the energy recovery mode (divided into coasting energy recovery and braking energy recovery; when driving in D gear, the speed reaches a certain value, the accelerator pedal is released (coasting) or the brake pedal is pressed, and the motor converts kinetic energy into electrical energy to charge the battery pack).

[0022] Furthermore, based on the motor mode, the torque limitation of the electric vehicle is obtained, including:

[0023] When the motor mode is PWM OFF mode, the maximum torque is limited to 0 and the vehicle has no power output;

[0024] When the motor mode is speed mode, the maximum torque limit is calculated based on the preset vehicle speed, the motor peak torque, and the current maximum discharge power of the battery;

[0025] When the motor mode is any of the zero torque mode, forward drive mode, reverse drive mode, and energy recovery mode, the maximum torque limit is calculated based on the peak torque of the motor and the current maximum charge / discharge power of the battery;

[0026] When the motor mode is a fault mode, the torque limitation of the electric vehicle is obtained according to the fault type.

[0027] Furthermore, obtaining the electric vehicle torque limit according to the fault type includes:

[0028] The fault type is a speed limit fault, and the maximum torque limit is calculated based on the maximum speed limit, the motor peak torque, and the current maximum discharge / charge power of the battery;

[0029] The fault type is a power limit fault, and the maximum torque limit is calculated based on the limited power coefficient, the peak torque of the motor, and the current maximum discharge / charge power of the battery;

[0030] The fault type is a power output prohibition fault. The maximum torque limit starts from the motor output torque at the time of the fault occurrence and drops to zero within a specified time. Before the maximum torque limit drops to zero, the vehicle can output power.

[0031] The fault type is a lower high-voltage fault, the maximum torque is limited to zero, and the vehicle has no power output.

[0032] The second object of the present invention is to provide a torque limiting system for an electric vehicle. The torque limiting system includes a motor mode determination module and an electric vehicle torque limiting module;

[0033] The motor mode determination module is used to determine the motor mode of the electric vehicle based on the vehicle state and vehicle information;

[0034] The electric vehicle torque limiting module is used to obtain the limit of the electric vehicle torque based on the motor mode.

[0035] The third object of the present invention is to provide a method for converting the motor mode of an electric vehicle. The conversion method includes a switching method and a torque limiting method for the electric vehicle. The switching method includes:

[0036] Switching any one of the PWM OFF mode, fault mode, forward drive mode, reverse drive mode, energy recovery mode, and speed mode to the zero torque mode, and switching the torque limits corresponding to the PWM OFF mode, fault mode, forward drive mode, reverse drive mode, energy recovery mode, speed mode, and zero torque mode to each other according to the motor mode switching sequence;

[0037] Switching between the PWM OFF mode and the fault mode, and switching between the torque limits corresponding to the PWM OFF mode and the fault mode;

[0038] Switch the PWM OFF mode to the zero torque mode, and then switch to any motor mode among the forward drive mode, reverse drive mode, energy recovery mode, and speed mode, and switch the torque limits corresponding to the PWM OFF mode, zero torque mode, forward drive mode, reverse drive mode, energy recovery mode, and speed mode according to the motor mode switching order;

[0039] Switching any motor mode among the forward drive mode, the reverse drive mode, the energy recovery mode, and the speed mode to the PWM OFF mode, and switching the torque limits corresponding to the forward drive mode, the reverse drive mode, the energy recovery mode, the speed mode, and the PWM OFF mode according to the motor mode switching sequence;

[0040] Switching the fault mode to the zero torque mode, and then switching to any motor mode among the forward drive mode, reverse drive mode, energy recovery mode, and speed mode, and switching the torque limits corresponding to the fault mode, zero torque mode, forward drive mode, reverse drive mode, energy recovery mode, and speed mode according to the motor mode switching order;

[0041] Switch any motor mode among the forward drive mode, reverse drive mode, energy recovery mode, and speed mode to the fault mode, and switch the torque limit corresponding to each motor mode according to the motor mode switching sequence;

[0042] Switch any motor mode among the forward drive mode, reverse drive mode, energy recovery mode, and speed mode to the zero torque mode, and then switch to any remaining motor mode among the forward drive mode, reverse drive mode, energy recovery mode, and speed mode, and switch the torque limits corresponding to the forward drive mode, reverse drive mode, energy recovery mode, speed mode, and zero torque mode according to the motor mode switching order.

[0043] Beneficial effects of the present invention:

[0044] The present invention provides a torque limiter and torque limiter method for an electric vehicle that can promptly respond to torque demands, thereby improving the stability and comfort of new energy vehicles. Other features and advantages of the present invention will be described in the following description and, in part, will become apparent from the description or be learned through practice of the present invention. The objectives and other advantages of the present invention can be achieved and obtained through the structures set forth in the description, claims, and accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0046] Figure 1 A flowchart of a torque limiting method according to an embodiment of the present invention is shown;

[0047] Figure 2 A schematic diagram of a method for converting motor modes of an electric vehicle according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0048] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0049] like Figure 1 As shown, the torque limiting method of an electric vehicle according to an embodiment of the present invention includes:

[0050] Determine the motor mode of the electric vehicle based on the vehicle status and vehicle information, wherein the vehicle status includes low-voltage state, high-voltage drivable state, and charging state; the vehicle information includes current gear, required torque, maximum battery discharge / charge power, motor peak torque, current vehicle speed, fault type, motor speed, DC-DC power, air conditioning power, PTC power, and special operating conditions; the fault type includes speed limit fault, power limit fault, power output prohibition fault, and high-voltage down fault; the special operating conditions include cruise control and anti-slope conditions;

[0051] Based on the motor mode, the electric vehicle torque limit is obtained.

[0052] In this embodiment, the vehicle state and vehicle information are used to determine the motor mode of the electric vehicle, specifically including the following steps:

[0053] ①1: When the vehicle state is a low voltage state or a charging state, the motor mode is a pulse width modulation off mode (PWM OFF) mode;

[0054] ①2: When the vehicle is in a high-voltage drivable state, the motor mode is determined based on whether the electric vehicle has a fault, including:

[0055] ①2②1: The electric vehicle has a fault and the motor mode is a fault mode;

[0056] ①2②2: If there is no fault in the electric vehicle, the motor mode is determined based on whether there is any special operating condition in the electric vehicle, including:

[0057] ①2②2③1: The electric vehicle has a special operating condition, and the motor mode is the speed mode;

[0058] ①2②2③2: If there is no special operating condition for the electric vehicle, the motor mode is determined based on the required torque and the current torque, including:

[0059] ①2②2③2④1: When the required torque is zero, the motor mode is zero torque mode;

[0060] When the required torque in ①2②2③2④2 is non-zero, the required torque is positive, the current gear is the forward gear, and the motor mode is the forward drive mode;

[0061] ①2②2③2④3: The required torque is negative, the current gear is reverse, and the motor mode is reverse drive mode;

[0062] ①2②2③2④4: The required torque is negative, the current gear is forward, and the motor mode is energy recovery mode. (①, ②, ③, and ④ represent the number of steps. The subscripts of ①, ②, ③, and ④ represent different situations in the same step.)

[0063] In this embodiment, the torque limitation of the electric vehicle is obtained based on the motor mode, including:

[0064] When the motor mode is PWM OFF mode, the maximum torque is limited to 0 and the vehicle has no power output;

[0065] When the motor mode is speed mode, the maximum torque limit is calculated based on the preset vehicle speed, the motor peak torque, and the current maximum discharge power of the battery. The specific calculation steps are as follows:

[0066] (1) Calculate TqMAX (the maximum torque currently allowed at the desired vehicle speed). The calculation formula is shown in formula (1):

[0067]

[0068] (1) Where V diff Refers to V req Refers to the expected vehicle speed, V actrefers to the actual vehicle speed, TqMAX refers to the maximum torque currently allowed at the desired vehicle speed, KP refers to the proportional coefficient, Ki refers to the integral coefficient, and t refers to time. TqMAX is limited according to the desired vehicle speed Vreq to prevent overshoot.

[0069] (2) Calculate the maximum torque that the motor can currently achieve. The calculation method is as follows:

[0070] a. Power-speed-torque map (curve chart) constructed based on motor test data;

[0071] b. Calculate the current allowable discharge power, which is the current maximum discharge power of the battery - DCDC power - air conditioning power - PTC power;

[0072] c. Based on the current allowable discharge power and motor speed, the maximum torque that the motor can currently achieve is obtained by looking up the table (i.e., map table);

[0073] (3) Limit torque = max (the maximum torque currently achievable by the motor, the peak torque of the motor, TqMAX);

[0074] When the motor mode is any of the zero torque mode, forward drive mode, reverse drive mode, and energy recovery mode, the maximum torque limit is calculated based on the motor peak torque and the current maximum charge / discharge power of the battery. The specific calculation method is as follows:

[0075] Zero Torque Mode:

[0076] (1) Calculate the maximum torque that the motor can currently achieve. The calculation method is as follows:

[0077] a. Power-speed-torque map (curve chart) constructed based on motor test data;

[0078] b. Calculate the current allowable discharge power, which is the current maximum discharge power of the battery - DCDC power - air conditioning power - PTC power;

[0079] c. Based on the current allowable discharge power and motor speed, the maximum torque that the motor can currently achieve is obtained by looking up the table (i.e., map table);

[0080] (2) Limit torque = min (the maximum torque that the motor can currently achieve, the peak torque of the motor);

[0081] Forward drive mode:

[0082] (1) Calculate the maximum torque that the motor can currently achieve. The calculation method is as follows:

[0083] a. Power-speed-torque map (curve chart) constructed based on motor test data;

[0084] b. Calculate the current allowable discharge power, which is the current maximum discharge power of the battery - DCDC power - air conditioning power - PTC power;

[0085] c. Based on the current allowable discharge power and motor speed, the maximum torque that the motor can currently achieve is obtained by looking up the table (i.e., map table);

[0086] (2) Limit torque = min (the maximum torque that the motor can currently achieve, the peak torque of the motor);

[0087] Reverse drive mode:

[0088] (1) Calculate the maximum torque that the motor can currently achieve. The calculation method is as follows:

[0089] a. Power-speed-torque map (curve chart) constructed based on motor test data;

[0090] b. Calculate the current allowable discharge power, which is the current allowable discharge power = the battery's current maximum discharge power - DC power - air conditioning power - PTC power;

[0091] c. Based on the current allowable discharge power and motor speed, the maximum torque that the motor can currently achieve is obtained by looking up the table (i.e., map table);

[0092] (3) Limit torque = max (maximum torque currently achievable by the motor, - |motor peak torque|);

[0093] Energy recovery mode:

[0094] (1) Calculate the maximum torque that the motor can currently achieve. The calculation method is as follows:

[0095] a. Power-speed-torque map (curve chart) constructed based on motor test data;

[0096] b. Calculate the current allowable charging power: Current allowable charging power = - |Battery current maximum charging power| - DC power;

[0097] c. Based on the current allowable charging power and motor speed, the maximum torque that the motor can currently achieve is obtained by looking up the table (i.e., map table);

[0098] (3) Limit torque = max (maximum torque currently achievable by the motor, - |motor peak torque|);

[0099] When the motor mode is a fault mode and the fault type is a power limit fault, the maximum torque limit is calculated based on the limited power coefficient, the motor peak torque, and the current maximum discharge / charge power of the battery.

[0100] The specific steps include:

[0101] (1) Calculate the maximum torque that the motor can currently achieve. The calculation method is as follows:

[0102] a. Power-speed-torque map (curve chart) constructed based on motor test data;

[0103] b. Calculate the current allowable discharge power, which is the current maximum discharge power of the battery - DCDC power - air conditioning power - PTC power;

[0104] c. Based on the current allowable discharge power and motor speed, the maximum torque that the motor can currently achieve is obtained by looking up the table (i.e., map table);

[0105] (2) Limit torque = K*min (the maximum torque currently achievable by the motor, the peak torque of the motor); K represents the limit power coefficient, K∈(0,1);

[0106] When the motor mode is fault mode and the fault type is speed limit fault, the maximum torque limit is calculated based on the maximum speed limit, the motor peak torque, and the current maximum discharge / charge power of the battery:

[0107] The specific calculation steps are as follows:

[0108] (1) Calculate TqMAX (the maximum torque currently allowed under the vehicle speed limit) using the formula (1);

[0109] (2) Calculate the maximum torque that the motor can currently achieve. The calculation method is as follows:

[0110] a. Power-speed-torque map (curve chart) constructed based on motor test data;

[0111] b. Calculate the current allowable discharge power, which is the current maximum discharge power of the battery - DCDC power - air conditioning power - PTC power;

[0112] c. Based on the current allowable discharge power and motor speed, the maximum torque that the motor can currently achieve is obtained by looking up the table (i.e., map table);

[0113] (3) Limit torque = max (the maximum torque currently achievable by the motor, the peak torque of the motor, TqMAX (the maximum torque currently allowed under the vehicle speed limit));

[0114] When the motor mode is in fault mode and the fault type is a power output prohibition fault, the maximum torque limit starts from the motor output torque at the time of the fault occurrence and drops to zero within 30 seconds. Before the maximum torque limit drops to zero, the vehicle can output power;

[0115] When the motor mode is a fault mode and the fault type is a lower high voltage fault, the maximum torque is limited to zero and the vehicle has no power output.

[0116] In other embodiments of the present invention, a torque limiting system for an electric vehicle is provided, comprising a motor mode determination module and an electric vehicle torque limiting module;

[0117] The motor mode determination module is used to determine the motor mode of the electric vehicle based on the vehicle state and vehicle information;

[0118] The electric vehicle torque limiting module is used to obtain the limit of the electric vehicle torque based on the motor mode.

[0119] In this embodiment, the motor mode determination module is used to determine the motor mode of the electric vehicle based on the vehicle state and vehicle information, including:

[0120] The motor mode determination module determines that the motor mode is a pulse width modulation off mode (PWM OFF) mode when the vehicle state is a low voltage state or a charging state;

[0121] The motor mode determination module determines the motor mode according to whether the electric vehicle has a fault when the vehicle state is in a high-voltage drivable state, including:

[0122] The motor mode determination module determines that the motor mode is a fault mode according to a fault occurring in the electric vehicle;

[0123] The motor mode determination module determines the motor mode according to whether the electric vehicle has any special operating conditions and whether there is any fault in the electric vehicle, including:

[0124] The motor mode determination module determines that the motor mode is a speed mode according to a special operating condition of the electric vehicle;

[0125] The motor mode determination module determines the motor mode according to the required torque and the current torque when no special operating conditions occur in the electric vehicle, including:

[0126] The motor mode determination module determines that the motor mode is a zero torque mode when the required torque is zero;

[0127] The motor mode determination module determines that the motor mode is a forward driving mode according to the required torque being positive and the current gear being a forward gear;

[0128] The motor mode determination module determines that the motor mode is a reverse drive mode according to the required torque being negative and the current gear being reverse;

[0129] The motor mode determination module determines that the motor mode is the energy recovery mode according to the required torque being negative and the current gear being a forward gear.

[0130] In this embodiment, the electric vehicle torque limiting module is used to obtain the electric vehicle torque limit based on the motor mode, including:

[0131] The electric vehicle torque limiting module limits the maximum torque to 0 when the motor mode is PWM OFF mode, and the vehicle has no power output;

[0132] The electric vehicle torque limiting module calculates the maximum torque limit according to the preset vehicle speed, the motor peak torque, and the current maximum discharge power of the battery when the motor mode is the speed mode;

[0133] The electric vehicle torque limiting module calculates the maximum torque limit according to the peak torque of the motor and the current maximum charge / discharge power of the battery when the motor mode is any one of the zero torque mode, the forward drive mode, the reverse drive mode, and the energy recovery mode;

[0134] When the motor mode is in fault mode and the fault type is a speed limit fault, the electric vehicle torque limit module calculates the maximum torque limit according to the maximum speed limit and the current maximum discharge / charge power of the battery;

[0135] When the motor mode is in fault mode and the fault type is a power limit fault, the electric vehicle torque limit module calculates the maximum torque limit according to the limited power coefficient, the peak torque of the motor, and the current maximum discharge / charge power of the battery;

[0136] When the motor mode is in fault mode and the fault type is a speed limit fault, the electric vehicle torque limit module calculates the maximum torque limit according to the maximum speed limit, the motor peak torque, and the current maximum discharge / charge power of the battery;

[0137] When the electric vehicle torque limiting module is in a fault mode according to the motor mode and the fault type is a power output prohibition fault, the maximum torque limit starts from the motor output torque at the time of the fault occurrence and drops to zero within 30 seconds. Before the maximum torque limit drops to zero, the vehicle can output power;

[0138] When the electric vehicle torque limiting module is in a fault mode according to the motor mode and the fault type is a lower high voltage fault, the maximum torque is limited to zero and the vehicle has no power output.

[0139] like Figure 2 As shown, a schematic diagram of a method for converting a motor mode of an electric vehicle according to an embodiment of the present invention includes:

[0140] Switching any of the PWM OFF mode, fault mode, forward drive mode, reverse drive mode, energy recovery mode, and speed mode to the zero torque mode, and switching the torque limits corresponding to the above motor modes to each other according to the motor mode switching order;

[0141] Switching between the PWM OFF mode and the fault mode, and switching between the torque limits corresponding to the PWM OFF mode and the fault mode;

[0142] Switch the PWM OFF mode to the zero torque mode, and then switch to any motor mode among the forward drive mode, reverse drive mode, energy recovery mode, and speed mode, and switch the torque limits corresponding to the above motor modes according to the motor mode switching order;

[0143] Switching any motor mode among the forward drive mode, reverse drive mode, energy recovery mode, and speed mode to the PWM OFF mode, and switching the torque limits corresponding to the above motor modes according to the motor mode switching sequence;

[0144] Switching the fault mode to the zero torque mode, and then switching to any motor mode among the forward drive mode, reverse drive mode, energy recovery mode, and speed mode, and switching the torque limits corresponding to the above motor modes according to the motor mode switching order;

[0145] Switch any motor mode among the forward drive mode, reverse drive mode, energy recovery mode, and speed mode to the fault mode, and switch the torque limits corresponding to the above motor modes according to the motor mode switching order;

[0146] Switch any motor mode among the forward drive mode, reverse drive mode, energy recovery mode, and speed mode to zero torque mode, and then switch to any remaining motor mode among the forward drive mode, reverse drive mode, energy recovery mode, and speed mode, and the torque limits corresponding to the above motor modes are switched according to the motor mode switching order.

[0147] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A torque limiting method for an electric vehicle, characterized in that: include: Determine the motor mode of the electric vehicle based on the vehicle status and vehicle information; Based on the motor mode, the torque limit of the electric vehicle is obtained; The step of obtaining the torque limitation of the electric vehicle based on the motor mode includes: When the motor mode is PWM OFF mode, the maximum torque is limited to 0 and the vehicle has no power output; When the motor mode is speed mode, the maximum torque limit is calculated based on the preset vehicle speed, the motor peak torque, and the current maximum discharge power of the battery, including: Calculate the maximum torque currently allowed at the desired vehicle speed; Calculate the maximum torque that the motor can currently achieve; Limit torque = max (the maximum torque currently achievable by the motor, the peak torque of the motor, the maximum torque currently allowed at the expected vehicle speed); When the motor mode is any of the zero torque mode, forward drive mode, reverse drive mode, and energy recovery mode, the torque limit is calculated based on the peak torque of the motor and the current maximum charge / discharge power of the battery, including: Zero Torque Mode: Calculate the maximum torque that the motor can currently achieve; Limit torque = min (the maximum torque that the motor can currently reach, the peak torque of the motor); Forward drive mode: Calculate the maximum torque that the motor can currently achieve; Limit torque = min (the maximum torque that the motor can currently reach, the peak torque of the motor); Reverse drive mode: Calculate the maximum torque that the motor can currently achieve; Limit torque = max (the maximum torque that the motor can currently reach, - |motor peak torque|); Energy recovery mode: Calculate the maximum torque that the motor can currently achieve; Limit torque = max (the maximum torque that the motor can currently reach, - |motor peak torque|); When the motor mode is a fault mode, the electric vehicle torque limitation is obtained according to the fault type, including: When the motor mode is a fault mode and the fault type is a power limit fault, the maximum torque limit is calculated based on the limited power coefficient, the motor peak torque, and the current maximum discharge / charge power of the battery, including: Calculate the maximum torque that the motor can currently achieve; Limit torque = K*min (the maximum torque currently achievable by the motor, the peak torque of the motor); K represents the limit power coefficient, K∈(0,1); When the motor mode is a fault mode and the fault type is a speed limit fault, the maximum torque limit is calculated based on the maximum speed limit, the motor peak torque, and the current maximum discharge / charge power of the battery, including: Calculate the maximum torque currently allowed under the vehicle speed limit; Calculate the maximum torque that the motor can currently achieve; Limit torque = max (the maximum torque currently achievable by the motor, the peak torque of the motor, the maximum torque currently allowed under the vehicle speed limit); When the motor mode is in fault mode and the fault type is a power output prohibition fault, the maximum torque limit starts from the motor output torque at the time of the fault occurrence and drops to zero within 30 seconds. Before the maximum torque limit drops to zero, the vehicle can output power; When the motor mode is in fault mode and the fault type is lower high voltage fault, the maximum torque is limited to zero and the vehicle has no power output; The calculation formula for the currently allowed maximum torque at the desired vehicle speed is as follows: Among them, Tq MAX Refers to the maximum torque currently allowed at the desired vehicle speed, K P Refers to the proportional coefficient, Ki refers to the integral coefficient, t refers to the time, , V req Refers to the expected vehicle speed, V act Refers to the actual vehicle speed; The calculation of the maximum torque currently achievable by the motor includes: Power-speed-torque map constructed based on motor test data; Calculate the current allowable discharge power, which is the current maximum discharge power of the battery - DCDC power - air conditioning power - PTC power. According to the current allowable discharge power and motor speed, the maximum torque that the motor can currently achieve is obtained by looking up the map table; The calculation formula for the currently allowed maximum torque at the limited vehicle speed is the same as the calculation formula for the currently allowed maximum torque at the desired vehicle speed.

2. The torque limiting method for an electric vehicle according to claim 1, characterized in that: The vehicle status includes a low-voltage state, a high-voltage drivable state, and a charging state.

3. The torque limiting method for an electric vehicle according to claim 1, characterized in that: The vehicle information includes the current gear, required torque, maximum battery discharge / charge power, motor peak torque, current vehicle speed, fault type, motor speed, DCDC power, air conditioning power, PTC power, and special operating conditions. The fault types include speed limit fault, power limit fault, power output prohibition fault, and high voltage fault; the special operating conditions include cruise control and anti-slope conditions.

4. A torque limiting method for an electric vehicle according to any one of claims 1 to 3, characterized in that: The determining of the motor mode of the electric vehicle based on the vehicle state and vehicle information includes: When the vehicle state is a low voltage state or a charging state, the motor mode is a pulse width modulation off mode, i.e., a PWMOFF mode; When the vehicle state is a high-voltage drivable state, the motor mode is determined based on whether the electric vehicle has any fault.

5. The torque limiting method for an electric vehicle according to claim 4, characterized in that: The method of determining the motor mode according to whether a fault occurs in the electric vehicle includes: The electric vehicle has a fault, and the motor mode is a fault mode; If no fault occurs in the electric vehicle, the motor mode is determined based on whether any special operating conditions occur in the electric vehicle.

6. The torque limiting method for an electric vehicle according to claim 5, characterized in that: The motor mode is determined based on whether the electric vehicle has a special operating condition, including: The electric vehicle has a special operating condition, and the motor mode is a speed mode; If no special operating conditions occur in the electric vehicle, the motor mode is determined based on the required torque and the current gear.

7. The torque limiting method for an electric vehicle according to claim 6, characterized in that: The determining of the motor mode according to the required torque and the current gear position includes: When the required torque is zero, the motor mode is zero torque mode; The required torque is positive, the current gear is the forward gear, and the motor mode is the forward drive mode; The required torque is negative, the current gear is reverse gear, and the motor mode is reverse drive mode; The required torque is negative, the current gear is the forward gear, and the motor mode is the energy recovery mode.

8. A torque limiting system for an electric vehicle, characterized in that: Including motor mode judgment module and electric vehicle torque limit module; The motor mode determination module is used to determine the motor mode of the electric vehicle based on the vehicle state and vehicle information; The electric vehicle torque limiting module is used to obtain the limit of the electric vehicle torque based on the motor mode; The step of obtaining the torque limitation of the electric vehicle based on the motor mode includes: When the motor mode is PWM OFF mode, the maximum torque is limited to 0 and the vehicle has no power output; When the motor mode is speed mode, the maximum torque limit is calculated based on the preset vehicle speed, the motor peak torque, and the current maximum discharge power of the battery, including: Calculate the maximum torque currently allowed at the desired vehicle speed; Calculate the maximum torque that the motor can currently achieve; Limit torque = max (the maximum torque currently achievable by the motor, the peak torque of the motor, the maximum torque currently allowed at the expected vehicle speed); When the motor mode is any of the zero torque mode, forward drive mode, reverse drive mode, and energy recovery mode, the torque limit is calculated based on the peak torque of the motor and the current maximum charge / discharge power of the battery, including: Zero Torque Mode: Calculate the maximum torque that the motor can currently achieve; Limit torque = min (the maximum torque that the motor can currently reach, the peak torque of the motor); Forward drive mode: Calculate the maximum torque that the motor can currently achieve; Limit torque = min (the maximum torque that the motor can currently reach, the peak torque of the motor); Reverse drive mode: Calculate the maximum torque that the motor can currently achieve; Limit torque = max (the maximum torque that the motor can currently reach, - |motor peak torque|); Energy recovery mode: Calculate the maximum torque that the motor can currently achieve; Limit torque = max (the maximum torque that the motor can currently reach, - |motor peak torque|); When the motor mode is a fault mode, the electric vehicle torque limitation is obtained according to the fault type, including: When the motor mode is a fault mode and the fault type is a power limit fault, the maximum torque limit is calculated based on the limited power coefficient, the motor peak torque, and the current maximum discharge / charge power of the battery, including: Calculate the maximum torque that the motor can currently achieve; Limit torque = K*min (the maximum torque currently achievable by the motor, the peak torque of the motor); K represents the limit power coefficient, K∈(0,1); When the motor mode is a fault mode and the fault type is a speed limit fault, the maximum torque limit is calculated based on the maximum speed limit, the motor peak torque, and the current maximum discharge / charge power of the battery, including: Calculate the maximum torque currently allowed under the vehicle speed limit; Calculate the maximum torque that the motor can currently achieve; Limit torque = max (the maximum torque currently achievable by the motor, the peak torque of the motor, the maximum torque currently allowed under the vehicle speed limit); When the motor mode is in fault mode and the fault type is a power output prohibition fault, the maximum torque limit starts from the motor output torque at the time of the fault occurrence and drops to zero within 30 seconds. Before the maximum torque limit drops to zero, the vehicle can output power; When the motor mode is in fault mode and the fault type is lower high voltage fault, the maximum torque is limited to zero and the vehicle has no power output; The calculation formula for the currently allowed maximum torque at the desired vehicle speed is as follows: Among them, Tq MAX Refers to the maximum torque currently allowed at the desired vehicle speed, K P Refers to the proportional coefficient, Ki refers to the integral coefficient, t refers to the time, , V req Refers to the expected vehicle speed, V act Refers to the actual vehicle speed; The calculation of the maximum torque currently achievable by the motor includes: Power-speed-torque map constructed based on motor test data; Calculate the current allowable discharge power, which is the current maximum discharge power of the battery - DCDC power - air conditioning power - PTC power. According to the current allowable discharge power and motor speed, the maximum torque that the motor can currently achieve is obtained by looking up the map table; The calculation formula for the currently allowed maximum torque at the limited vehicle speed is the same as the calculation formula for the currently allowed maximum torque at the desired vehicle speed.

Images