Test method and system for energy and efficiency of new energy vehicle driving system

Abstract

The application discloses a kind of new energy automobile driving system energy and efficiency test method and system, test method includes setting four motor test bench parameter;Fitting test vehicle road resistance;Through power analyzer test battery power, calculate vehicle power battery electric energy;Through power analyzer test vehicle driving motor electric power, calculate vehicle driving motor drive electric energy and brake recovery electric energy;Through CAN bus reads the speed of driving motor, torque, calculates driving mechanical energy and brake mechanical energy;Through four motor test bench test wheel end speed, torque, calculates the mechanical energy of test vehicle wheel end;Under different cycle conditions, the energy and efficiency of driving state and braking state are calculated.The application realizes new energy automobile driving system energy management and efficiency test and accurate evaluation under different cycle conditions based on four motor test bench, with the characteristics of high test precision, wide practical range.

Description

Technical Field

[0001] This invention belongs to the field of driving energy consumption and braking energy recovery technology of new energy vehicle drive systems, and in particular relates to the testing of energy consumption in driving state and energy recovery in braking state of pure electric vehicle drive systems. Specifically, it relates to a method and system for testing the energy and efficiency of new energy vehicle drive systems. Background Technology

[0002] The driving range of new energy vehicles varies greatly under different operating conditions. This is due to two main reasons: firstly, the vehicle's overall requirements differ under different conditions; and secondly, energy consumption and powertrain efficiency vary significantly under different operating conditions. Therefore, it is necessary to conduct precise testing on the energy management and system efficiency of the vehicle under different operating conditions.

[0003] Currently, most people believe that the energy consumption of new energy vehicles under different operating cycles depends on the battery. In reality, energy consumption under different operating cycles and how to reduce it primarily depends on the motor system and the electric drive system; the battery is only one factor affecting energy consumption. Therefore, when researching energy management under different operating cycles for new energy vehicles, it is crucial to thoroughly study the energy consumption of the electric drive system, which is also significant for more accurate estimation of remaining range. The electric drive system, including the powertrain and transmission system, is the core of new energy vehicles, comprising important components such as the battery, motor, controller, reducer, drive shaft, and brakes.

[0004] In the cyclic operation of new energy vehicles, electrical energy is converted into mechanical energy for wheel-end propulsion through the electric drive system. However, not 100% of this electrical energy is converted into mechanical energy for propulsion; some energy remains unutilized. Therefore, further research is needed on the effective utilization rate of electrical energy conversion for propulsion during driving and the recovery rate of wheel-end mechanical energy converted into electrical energy for storage and reuse during regenerative braking. Summary of the Invention

[0005] Based on the above, the purpose of this invention is to propose a testing method and system for the energy and efficiency of a new energy vehicle drive system, so as to achieve a thorough research and development of the electric drive system of new energy vehicles through a rapid testing scheme.

[0006] To achieve the objectives of this invention, the technical solution provided by this invention is as follows:

[0007] First aspect

[0008] This invention provides a method for testing the energy and efficiency of a new energy vehicle drive system. The method is based on a four-motor test bench and includes the following steps:

[0009] Step 1: Install the current sensor and power analyzer at the power battery and drive motor assembly terminals;

[0010] Step 2: Fit the road resistance of the test vehicle and set the parameters of the four-motor test bench;

[0011] Step 3: The test vehicle undergoes different cyclic operating condition tests on the assembly bench;

[0012] Step 4: Measure the current, voltage, and power entering the drive motor assembly; read the speed and torque of the drive motor from the CAN bus and calculate its power; record the speed and torque at the wheel ends of the test vehicle and calculate its power.

[0013] Step 5: Calculate the energy and efficiency of the drive system under different cyclic operating conditions.

[0014] Step 2 includes the following:

[0015] Step 2-1: First, the test vehicle undergoes a full-vehicle transmission system resistance test on the assembly bench, and the test results are recorded. A new set of road resistances is obtained by subtracting the transmission system resistance from the actual road resistance of the test vehicle. Then, the road resistance formula F = a + bV + cV is applied. 2 The relationship between vehicle speed and resistance is shown, where 'a' represents a constant resistance term independent of speed; 'b' represents the resistance term related to the first-order velocity; and 'c' represents the resistance term related to the second-order velocity. A new quadratic function for road resistance, F′=a′+b′V+c′V, is fitted to this function. 2 , and serve as the load resistance of the test vehicle;

[0016] Step 2-2: Set the loading resistance of the four-motor test bench F′=a′+b′V+c′V 2 ;

[0017] Steps 2-3: Set the rolling radius and overall vehicle test mass of the test vehicle in the assembly test bench;

[0018] Steps 2-4: Establish a CAN communication connection between the assembly bench and the NI device, and send the vehicle speed signal from the assembly bench to the NI data acquisition device.

[0019] In step 3, the driver performs a cyclic test on the assembly bench based on the vehicle speed prompts fed back by the host computer of the vehicle speed prompt system. The cyclic test involves three regulatory cyclic test conditions: NEDC, WLTC, and CLTC. Each cyclic test condition is repeated twice.

[0020] Step 4 includes the following:

[0021] Step 4-1: Read the current I entering the drive motor assembly terminal from the power analyzer. dc Voltage U dc and power Prms ;

[0022] Step 4-2: Read the speed and torque of the CAN bus driven motor, and calculate it according to formula P. motor =Tn / 9550 to calculate the power P of its drive motor motor Where T represents torque and n represents rotational speed, the wheel-end rotational speed and torque of the test vehicle are recorded, and the same formula P is used. wheel =Tn / 9550 Calculate its wheel end power P wheel .

[0023] Step 5 includes the following:

[0024] Step 5-1: Input current I at the drive motor assembly terminal in each cycle condition dc =0 is the boundary, according to the integral formula I were obtained respectively dc When the value is greater than 0, the drive energy consumption W entering the drive motor assembly terminal is... battery1 ;I dc When <0, the braking energy recovery W battery0 In the formula, t1 is the start time of the cycle; t2 is the end time of the cycle.

[0025] Step 5-2: Same as step 5-1 above, using I dc =0 is the boundary, according to the integral formula I were obtained respectively dc When >0, the mechanical work W in the driving state motor1 ;I dc When <0, the mechanical work W of the drive motor in the regenerative braking state is motor0 ;

[0026] Step 5-3: Same as Step 5-1 above, using I... dc =0 is the boundary, according to the integral formula When I dc When the energy W is greater than 0, the mechanical energy W exerted by the wheel ends in the driving state of the test vehicle is measured. wheel1 ; when I dc When <0, the wheel-end mechanical energy W of the test vehicle in regenerative braking state is... wheel0 ;

[0027] Step 5-4: In each cycle, the input current I at the drive motor assembly terminal is... dc =0 is the boundary, when I dc When the value is greater than 0, calculate the efficiency of the drive motor in the driving state. When I dc When <0, calculate the efficiency of the drive motor in the regenerative braking state.

[0028] Step 5-5: In each cycle, the input current I at the drive motor assembly terminal is... dc =0 is the boundary, when I dc When the value is greater than 0, calculate the efficiency of the drive assembly in the drive state. When I dc When <0, calculate the efficiency of the drive assembly in the regenerative braking state.

[0029] Second aspect

[0030] Corresponding to the above method, the present invention provides a testing system for the energy and efficiency of a new energy vehicle drive system. The system is a testing system for the energy and efficiency of a new energy vehicle drive system under cyclic operating conditions based on a four-motor test bench. It includes a four-motor test bench, a power analyzer, a current sensor, a CAN bus interface, and a speed and torque sensor. The speed and torque sensor is integrated on the four-motor test bench. The current sensor is arranged on the high-voltage wiring harness of the vehicle's power battery and drive motor. The power analyzer is used to collect current and voltage and calculate real-time power. The CAN bus interface is used for collecting test data. The speed and torque sensor is used to test the speed and torque of the output shaft. The four-motor test bench is used to conduct tests on the energy management and efficiency of the drive system under cyclic operating conditions.

[0031] All the above test data are integrated into the assembly bench system and collected and recorded at the same frequency to facilitate subsequent data processing.

[0032] Compared with existing technologies, this invention uses a four-motor test bench to realize energy management and efficiency testing and accurate evaluation of the drive system under different cyclic operating conditions of new energy vehicles, and has the characteristics of high testing accuracy and wide applicability. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the test method flow provided in an embodiment of the present invention;

[0034] Figure 2 This is a schematic diagram of the test system structure provided in an embodiment of the present invention. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] This invention provides a method and system for testing the energy and efficiency of a new energy vehicle drive system. The test system includes a four-motor test bench, a data acquisition system, a power analyzer, a vehicle driving condition indication system, a CAN bus interface, and a host computer. The test method includes setting the parameters of the four-motor test bench; fitting the road resistance of the test vehicle; testing the battery power using the power analyzer and calculating the vehicle's power battery energy; testing the power of the vehicle's drive motors using the power analyzer and calculating the drive energy and regenerative braking energy of the drive motors; reading the speed and torque of the drive motors via the CAN bus and calculating the drive mechanical energy and braking mechanical energy; testing the wheel-end speed and torque using the four-motor test bench and calculating the mechanical energy at the wheel ends of the test vehicle; and calculating the energy and efficiency of the drive and braking states under different cyclic operating conditions. This invention, based on a four-motor test bench, enables energy management and efficiency testing and accurate evaluation of the drive system of new energy vehicles under different cyclic operating conditions, featuring high testing accuracy and wide applicability.

[0037] like Figure 1 and Figure 2 As shown, this embodiment provides a method for testing the energy and efficiency of a new energy vehicle drive system, including the following steps:

[0038] Step 1: Install the current sensor and power analyzer at the power battery and drive motor assembly terminals;

[0039] Step 2: Fit the road resistance of the test vehicle and set the parameters of the four-motor test bench;

[0040] Step 3: The test vehicle undergoes different cyclic operating condition tests on the assembly bench;

[0041] Step 4: Measure the current, voltage, and power entering the drive motor assembly; read the speed and torque of the drive motor from the CAN bus and calculate its power; record the speed and torque at the wheel ends of the test vehicle and calculate its power.

[0042] Step 5: Calculate the energy and efficiency of the drive system under different operating conditions;

[0043] Preferably, step 2 includes the following:

[0044] Step 2-1: First, the test vehicle undergoes a full-vehicle transmission system resistance test on the assembly bench, and the test results are recorded. A new set of road resistances is obtained by subtracting the transmission system resistance (since the transmission system resistance is already present on the bench, no further loading is needed) from the actual road resistance of the test vehicle. Then, the road resistance formula F = a + bV + cV is applied. 2The relationship between vehicle speed and resistance is shown in the figure. 'a' represents a constant resistance term independent of speed (such as road friction); 'b' represents resistance related to the first-order term of speed (such as transmission resistance); and 'c' represents resistance related to the quadratic term of speed (such as wind resistance). A new quadratic function for road resistance, F′=a′+b′V+c′V, is fitted to this function. 2 And it serves as the load resistance for the test vehicle.

[0045] Step 2-2: Set the loading resistance of the four-motor test bench F′=a′+b′V+c′V 2 ;

[0046] Steps 2-3: Set the rolling radius and overall vehicle test mass of the test vehicle in the assembly test bench;

[0047] Steps 2-4: Establish a CAN communication connection between the assembly bench and the NI device, and send the vehicle speed signal from the assembly bench to the NI data acquisition device.

[0048] Preferably, in step 3, the driver performs a cyclic test on the assembly bench based on the vehicle speed prompts fed back by the host computer of the vehicle speed prompt system. The cyclic test involves three regulatory cyclic tests: NEDC, WLTC, and CLTC, and each cyclic test is repeated twice.

[0049] Preferably, step 4 includes the following:

[0050] Step 4-1: Read the current I entering the drive motor assembly terminal from the power analyzer. dc Voltage U dc and power P rms ;

[0051] Step 4-2: Read the speed and torque of the CAN bus driven motor, and calculate it according to formula P. motor =Tn / 9550 to calculate the power P of its drive motor motor (T represents torque, n represents speed), record the wheel-end speed and torque of the test vehicle, and also according to the above formula P. wheel =Tn / 9550 to calculate its wheel end power P wheel ;

[0052] Preferably, step 5 includes the following:

[0053] Step 5-1: Input current I at the drive motor assembly terminal in each cycle condition dc =0 is the boundary, according to the integral formula I were obtained respectively dc When the value is greater than 0, the drive energy consumption W entering the drive motor assembly terminal is... battery1 ;I dc When <0, the braking energy recovery W battery0In the formula, t1 is the start time of the cycle; t2 is the end time of the cycle.

[0054] Step 5-2: Same as step 5-1 above, using I dc =0 is the boundary, according to the integral formula I were obtained respectively dc When >0, the mechanical work W in the driving state motor1 ;I dc When <0, the mechanical work W of the drive motor in the regenerative braking state is motor0 ;

[0055] Step 5-3: Same as Step 5-1 above, using I... dc =0 is the boundary, according to the integral formula When I dc When the energy W is greater than 0, the mechanical energy W exerted by the wheel ends in the driving state of the test vehicle is measured. wheel1 ; when I dc When <0, the wheel-end mechanical energy W of the test vehicle in regenerative braking state is... wheel0 ;

[0056] Step 5-4: In each cycle, the input current I at the drive motor assembly terminal is... dc =0 is the boundary. When I dc When the value is greater than 0, calculate the efficiency of the drive motor in the driving state. When I dc When <0, calculate the efficiency of the drive motor in the regenerative braking state.

[0057] Step 5-5: In each cycle, the input current I at the drive motor assembly terminal is... dc =0 is the boundary. When I dc When the value is greater than 0, calculate the efficiency of the drive assembly in the drive state. When I dc When <0, calculate the efficiency of the drive assembly in the regenerative braking state.

[0058] It should be noted that the four-motor test bench features high testing accuracy, wide capability coverage, customizable operating conditions, and high integration. The wheel-end torque sensors integrated into the bench further reduce pre-test preparation time. It can cover almost all the testing content of a complete new energy vehicle, eliminating the need for frequent vehicle disassembly and reassembly and the time spent searching for other related testing equipment resources, providing favorable conditions. Therefore, this testing method was chosen based on the four-motor test bench.

[0059] In addition, this invention provides a testing system for the energy and efficiency of a new energy vehicle drive system under cyclic operating conditions, based on a four-motor test bench. The system includes a four-motor test bench, a power analyzer, a current sensor, a CAN bus interface, and speed and torque sensors. The speed and torque sensors are integrated on the four-motor test bench. The current sensors are arranged on the high-voltage wiring harnesses of the vehicle's power battery and drive motor. The power analyzer is used to collect current and voltage data and calculate real-time power. The CAN bus interface is used for acquiring test data. The speed and torque sensors are used to test the speed and torque of the output shaft. The four-motor test bench is used to conduct tests on the energy management and efficiency of the drive system under cyclic operating conditions.

[0060] All the above test data are integrated into the assembly bench system and collected and recorded at the same frequency to facilitate subsequent data processing.

[0061] The above experimental methods can intuitively show the electrical energy and driving mechanical energy consumed and recovered under the two states of driving and braking recovery in cyclic operating conditions. At the same time, they can also reflect the proportion of mutual conversion between electrical energy and mechanical energy under the two states, providing strong data support for the development and research of electric drive system performance.

[0062] Finally, it should be noted that the above embodiments are merely illustrative and explanatory of the present invention, and are not intended to limit the present invention to the scope of the described embodiments. Furthermore, those skilled in the art will understand that the present invention is not limited to the above embodiments, and many more variations and modifications can be made based on the teachings of the present invention, all of which fall within the scope of protection claimed by the present invention.

Claims

1. A method for testing the energy and efficiency of a new energy vehicle drive system, characterized in that, The method described is a test method for the energy and efficiency of the drive system of a new energy vehicle under cyclic operating conditions based on a four-motor test bench, and includes the following steps: Step 1: Install the current sensor and power analyzer at the power battery and drive motor assembly terminals; Step 2: Fit the road resistance of the test vehicle and set the parameters of the four-motor test bench; Step 3: The test vehicle undergoes different cyclic operating condition tests on the assembly bench; Step 4: Measure the current, voltage, and power entering the drive motor assembly; read the speed and torque of the drive motor from the CAN bus and calculate its power; record the speed and torque at the wheel ends of the test vehicle and calculate its power. Step 5: Calculate the energy and efficiency of the drive system under different operating conditions; Step 2 includes the following: Step 2-1: First, the test vehicle undergoes a full-vehicle transmission system resistance test on the assembly bench, and the test results are recorded. A new set of road resistances is obtained by subtracting the transmission system resistance from the actual road resistance of the test vehicle. Then, the road resistance formula F=a+bV+cV is applied. 2 The relationship between vehicle speed and resistance is shown, where 'a' represents a constant resistance term independent of speed; 'b' represents the resistance term related to the first-order velocity; and 'c' represents the resistance term related to the second-order velocity. A new quadratic function for road resistance, F′=a′+ b′V + c′V, is then fitted. 2 , and serve as the load resistance of the test vehicle; Step 2-2: Set the loading resistance of the four-motor test bench to F′=a′+ b′V + c′V 2 ; Steps 2-3: Set the rolling radius and overall vehicle test mass of the test vehicle in the assembly test bench; Steps 2-4: Establish a CAN communication connection between the assembly bench and the NI device, and send the vehicle speed signal from the assembly bench to the NI data acquisition device; Step 5 includes the following: Step 5-1: Input current I at the drive motor assembly terminal in each cycle condition dc =0 is the boundary, according to the integral formula W battery = I were obtained respectively dc When the value is greater than 0, the drive energy consumption W entering the drive motor assembly terminal is... battery1 I dc When <0, the braking energy recovery W battery0 In the formula, t1 is the start time of the cycle; t2 is the end time of the cycle. Step 5-2: Same as step 5-1 above, using I dc =0 is the boundary, according to the integral formula W motor = I were obtained respectively dc When >0, the mechanical work W in the driving state motor1 I dc When <0, the mechanical work W of the drive motor in regenerative braking state is... motor0 ; Step 5-3: Same as Step 5-1 above, using I... dc =0 is the boundary, according to the integral formula W wheel = When I dc When the energy is greater than 0, the mechanical energy W exerted by the wheel ends in the driving state of the test vehicle is measured. wheel1 ; when I dc When <0, the wheel-end mechanical energy W of the test vehicle in regenerative braking state is... wheel0 ; Step 5-4: In each cycle, the input current I at the drive motor assembly terminal is... dc =0 is the boundary, when I dc When the value is greater than 0, calculate the efficiency η of the drive motor in the driving state. motor1 = ; when I dc When <0, calculate the efficiency η of the drive motor in the regenerative braking state. motor0 = ; Step 5-5: In each cycle, the input current I at the drive motor assembly terminal is... dc =0 is the boundary, when I dc When the value is greater than 0, calculate the efficiency η of the drive assembly in the drive state. powertrain1 = ; when I dc When <0, calculate the efficiency η of the drive assembly in the regenerative braking state. powertrain0 = .

2. The method for testing the energy and efficiency of a new energy vehicle drive system according to claim 1, characterized in that, In step 3, the driver performs a cyclic test on the assembly bench based on the vehicle speed prompts fed back by the host computer of the vehicle speed prompt system. The cyclic test involves three regulatory cyclic test conditions: NEDC, WLTC, and CLTC. Each cyclic test condition is repeated twice.

3. The method for testing the energy and efficiency of a new energy vehicle drive system according to claim 1, characterized in that, Step 4 includes the following: Step 4-1: Read the current I entering the drive motor assembly terminal from the power analyzer. dc Voltage U dc and power P rms ; Step 4-2: Read the speed and torque of the CAN bus driven motor, and calculate it according to formula P. motor =Tn / 9550 Calculate its drive motor power P motor Where T represents torque and n represents rotational speed, the wheel-end speed and torque of the test vehicle are recorded, also according to the formula P wheel Calculate the wheel end power P using =Tn / 9550. wheel .

4. A testing system for the energy and efficiency of a new energy vehicle drive system, used to perform the testing method for the energy and efficiency of a new energy vehicle drive system as described in any one of claims 1-3, characterized in that, The system is a test system for the energy and efficiency of the drive system of a new energy vehicle under cyclic operating conditions based on a four-motor test bench. It includes a four-motor test bench, a power analyzer, a current sensor, a CAN bus interface, and a speed and torque sensor. The speed and torque sensor is integrated on the four-motor test bench. The current sensor is arranged on the high-voltage wiring harness of the vehicle's power battery and drive motor. The power analyzer is used to collect current and voltage and calculate real-time power. The CAN bus interface is used for the acquisition of test data. The speed and torque sensor is used to test the speed and torque of the output shaft; the four-motor test bench is used to test the energy management and efficiency of the drive system under cyclic operating conditions. All the above test data are integrated into the assembly bench system and collected and recorded at the same frequency to facilitate subsequent data processing.

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