CN105893648B

CN105893648B - Method for selecting wire diameter of high-voltage electric wire of hybrid power and electric automobile

Info

Publication number: CN105893648B
Application number: CN201510039400.8A
Authority: CN
Inventors: 粟亮; 孙韬; 王成君; 杨晓军
Original assignee: Aptiv Electric System Co ltd
Current assignee: Aptiv Electric System Co ltd
Priority date: 2015-01-26
Filing date: 2015-01-26
Publication date: 2020-10-16
Anticipated expiration: 2035-01-26
Also published as: CN105893648A

Abstract

The invention relates to a method for selecting the wire diameter of a high-voltage electric wire of a hybrid power and electric automobile, which is characterized by comprising the following steps of: 1) establishing a vehicle model, and performing electrical load simulation to obtain a high-voltage wire current curve; 2) establishing a conductor model, and carrying out conductor thermal simulation according to the high-voltage conductor current curve to obtain real-time temperature rise data of the high-voltage conductor; 3) selecting an initial wire diameter according to the real-time temperature rise data of the high-voltage wire; 4) and judging whether the selected initial wire diameter meets the temperature rise condition, if so, taking the selected wire diameter as a final value, and if not, returning to the step 2). Compared with the prior art, the method has the advantages of accurate line diameter selection, high precision and the like.

Description

Method for selecting wire diameter of high-voltage electric wire of hybrid power and electric automobile

Technical Field

The invention relates to the field of hybrid power and electric automobiles, in particular to a method for selecting the wire diameter of a high-voltage electric wire of a hybrid power and electric automobile.

Background

The driving energy source of the automobile is being switched from an internal combustion engine to a chemical battery, and if a line diameter selection method of a low-voltage lead-Isotemp curve method is continuously used, the design problem of a high-voltage lead is solved, and wrong design can be caused. The high-voltage wires connect high-voltage components such as a battery pack, an inverter, and a drive motor. These components are used to meet the power and energy requirements for vehicle drive and braking energy feedback. During operation of the entire vehicle, the current on the circuit connecting the high-voltage components fluctuates strongly. The Isotemp curve method can only handle steady state current conditions. Thus, if the design of the high voltage conductor is continued, erroneous results may result.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide a method for selecting the wire diameter of the high-voltage electric wire of the hybrid power and electric automobile, which is accurate in wire diameter selection and high in precision.

The purpose of the invention can be realized by the following technical scheme:

a method for selecting the wire diameter of a high-voltage electric wire of a hybrid power and electric automobile comprises the following steps:

1) establishing a vehicle model, and performing electrical load simulation to obtain a high-voltage wire current curve;

2) establishing a conductor model, and carrying out conductor thermal simulation according to the high-voltage conductor current curve to obtain real-time temperature rise data of the high-voltage conductor;

3) selecting an initial wire diameter according to the real-time temperature rise data of the high-voltage wire;

4) and judging whether the selected initial wire diameter meets the temperature rise condition, if so, taking the selected wire diameter as a final value, and if not, returning to the step 2).

The vehicle model comprises a driving condition module, a vehicle dynamics module, a mechanical transmission module, a driving motor module, an inverter module and a battery pack module.

The vehicle model also includes a motor controller module and a battery controller module.

The step 1) is specifically as follows:

101) establishing a vehicle model, setting a vehicle running state and vehicle parameters, and calculating direct current and alternating current of a high-voltage electrical load;

102) simulating the vehicle model to obtain direct current and alternating current of the high-voltage electrical load of the simulation test;

103) and judging whether the calculated value in the step 101) is matched with the test value in the step 102), if so, outputting a high-voltage wire current curve of the simulation test, otherwise, modifying the vehicle model, and returning to the step 101).

The step 2) is specifically as follows:

201) establishing a lead model, setting the environmental temperature and lead parameters, and selecting the minimum selectable value of the wire diameter of the lead;

202) taking the current curve of the high-voltage wire as the input of a wire model, and carrying out wire thermal simulation to obtain the temperature rise of the conductor wire core and the surface of the insulator of the wire subjected to simulation test;

203) calculating the temperature rise of the conductor core and the surface of the insulator of the lead;

204) and judging whether the test value in the step 202) is matched with the calculated value in the step 203), if so, outputting real-time temperature rise data of the high-voltage wire subjected to the simulation test, otherwise, modifying the wire model, and returning to the step 203).

Compared with the prior art, the invention has the following advantages:

(1) according to the characteristics of the high-voltage wire, a new method is set, the surface temperature rise of a conductor wire core and an insulator of the high-voltage wire is calculated according to a real load current curve, then the wire diameter of the wire is selected according to temperature rise data, the wire diameter is selected accurately, and the method is suitable for selecting the wire diameter of a high-voltage electric wire harness.

(2) When a vehicle model and a wire model are established, the method provided by the invention is combined with test data to calibrate and correct partial parameters, and the model precision is high.

(3) The invention can effectively solve the design problem of the high-voltage wire, thereby ensuring the use safety of the automobile.

Drawings

FIG. 1 is a schematic diagram of an exemplary high voltage conductor system in an electric vehicle;

FIG. 2 is a schematic flow chart of a method for selecting a wire diameter according to the present invention;

FIG. 3 is an exemplary architecture of a vehicle model of the present invention;

figure 4 is an exemplary architecture of a wire pattern of the present invention.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments. The method described below may be used with any hybrid and electric vehicle. The high-voltage component is used for driving the vehicle. Electric vehicles are driven by batteries alone, and hybrid vehicles are driven by both an internal combustion engine and a battery. High voltage, as known in the present invention, refers to voltages greater than 60 volts.

As shown in fig. 1, an exemplary high voltage conductor system 00 in an electric vehicle is shown. The system 00 comprises a high voltage battery pack 30 that can receive charging from the outside of the vehicle via an ac plug 10 and an on-board charger 20. The high voltage battery pack 30 provides power to a 12V system 50 (e.g., battery and low voltage loads) via a DC-DC converter 40. The high-voltage battery pack 30 also supplies power to the electric heater 70 and the electric air conditioner 80 (including an air conditioner inverter 81 and an air conditioner compressor 82). Most of the energy and power of the high voltage battery pack 30 is used to power an inverter 60, which converts high voltage dc power to high voltage ac power to power a drive motor 90. During vehicle braking, the drive motor 90 and inverter 60 convert braking energy into high voltage dc power that is provided to the high voltage battery pack for charging. Wherein the high

voltage connection circuit

11, 21, 22, 31, 32, 33, 34, 35, 36, 37, 38, 61, 62, 63 distributes and transmits high voltage electrical power in the high voltage components. In particular, the currents delivered by the high

voltage dc circuits

31, 32 and the high voltage ac

circuits

61, 62, 63 fluctuate strongly with changes in the speed and acceleration of the vehicle.

For high voltage harness design, the traditional Isotemp curve method is adopted to select the wire diameter of the high voltage wire. The Isotemp curve assumes that the current carried by the high voltage harness is stable, i.e., always steady. However, such an assumption is not true for the high-

voltage connection loops

31, 32, 61, 62, 63, since the actual current is dynamic and fluctuates strongly. Therefore, a new method is proposed for selecting the wire diameter of a high-voltage electrical harness.

The embodiment of the invention provides a method for selecting the wire diameter of a high-voltage electric wire of a hybrid power and electric automobile. The method consists of three steps: 1) electrical load simulation and test; 2) conducting wire thermal simulation and test, and 3) vehicle-mounted test verification.

The method comprises the following steps of 1) introducing a current behavior characteristic of a vehicle model simulation electric load, and 2) introducing a temperature rise characteristic of a wire model simulation wire, wherein the two models are firstly constructed based on theoretical analysis, and then are calibrated and corrected by combining test data through partial parameters so as to meet the requirement of satisfactory precision.

As shown in fig. 2, the method 100 of this embodiment specifically includes the following steps:

step 101, start.

Step 102, vehicle operating conditions are set. Vehicle operating conditions include driving conditions (time profile of speed trajectory) and road grade.

Step 103, setting vehicle parameters such as wind resistance coefficient, tire rolling resistance coefficient, vehicle cross-sectional area, tire radius, rear axle final reduction ratio, gear ratio of transmission gear train, mechanical characteristics and efficiency map of driving motor, peak power and efficiency map of inverter, braking energy recovery characteristics of vehicle, battery state of charge SOC range, rated capacity and rated voltage of battery, etc. These parameters define the load power and load torque request on the motor output shaft, and also determine the current and voltage profiles of the high voltage battery pack.

And step 104, after the vehicle parameters are set, calculating the direct current and the alternating current of the high-voltage electrical load by using the vehicle simulation model to calculate the alternating current and the direct current of the high-voltage electrical load. FIG. 3 is a block diagram illustrating an exemplary architecture of a vehicle model. One exemplary architecture of a vehicle model, such as the structural diagram 200, includes a driving conditions module 210, a vehicle dynamics module 220, a mechanical transmission module 230, a motor controller module 240, a drive motor module 250, an inverter module 260, a braking energy recovery controller module 270, and a high voltage battery module 280.

The driving conditions module 210 outputs a time-varying speed trajectory, via connection 211, to the vehicle dynamics module 220. The user may select a standard or customized driving cycle, such as a European New Driving cycle regime (NEDC), a U.S. City Driving cycle regime (UDDS), or a Japanese driving cycle regime (J1015). Another option provided by driving conditions 210 is road grade, which may be defined as a function of time or a fixed value. The function of the vehicle dynamics module 220 is to calculate the vehicle drive force demand and transmit the settlement result to the mechanical transmission module 230 via connection 221. As is well known, the vehicle driving force is the sum of static friction force, rolling resistance, wind resistance, and acceleration force. All of these forces are a function of vehicle speed. Thus, the driving force obtained by the vehicle dynamics module 220 is calculated based on the vehicle speed data transmitted by the driving conditions module 210. The mechanical transmission module 230 consists of wheels, a rear axle final drive, a simple or complex transmission gear train. The mechanical transmission module 230 simulates the true driveline of the vehicle to reflect the rotational speed and torque transfer relationship from the wheels to the drive motor output shaft. The configuration and parameters of the mechanical transmission module 230 may be set according to the actual transmission system. The mechanical transmission module 230 provides as input a time function of vehicle load torque and speed to the motor controller module 240 via connection 231. The primary function of the motor controller module 240 is to determine whether the drive motor can meet the load torque and speed requested by the vehicle. By comparing the load torque and the rotational speed requested by the vehicle with the driving performance boundary of the driving motor, it can be determined whether the driving motor can satisfy the load torque and the rotational speed requested by the vehicle. If the latter exceeds the former drivability limit, it is necessary to limit the request for vehicle load torque and rotational speed to the maximum values allowed. After processing, a reasonable vehicle load torque and speed request is transmitted from 240 through connection 241 to 250. The drive motor module 250, may be a simple map of efficiency, with motor efficiency being a function of motor speed and motor torque. Or a complex equivalent circuit, which is used for replacing the feedback control loop. In order to obtain the 3-phase alternating voltage and the 3-phase alternating current at the input end of the driving motor, a complex circuit model needs to be established. The primary function of the drive motor module 250 is to simulate the input-output characteristics of a real drive motor. Which converts the request from vehicle load torque and speed to an electrical power request at the output of the inverter module 260 via connection 251. The inverter module 260 may be a simple efficiency map with input-to-output conversion efficiency as a function of motor speed and torque. The electrical power request at the input of the inverter module 260 is transferred to the braking energy recovery controller module 270 via connection 261. The latter is a braking energy feedback controller module, which implements a braking energy feedback control strategy and calculates the real battery charging and discharging power request during the acceleration and deceleration of the vehicle. Overcharge or overdischarge of a high voltage battery pack can be detrimental to its performance and life. Therefore, almost all hybrid and electric vehicles need to include a braking energy feedback control strategy, and it is necessary to add such a module in the vehicle simulation model architecture. The braking energy recovery controller module 270 outputs a real battery charge and discharge power request to the high voltage battery module 280 via connection 271. The last high voltage battery module 280 implements the electrical or also thermal behavior of the high voltage battery pack according to the charge and discharge power request. The output terminal voltage, output terminal current, state of charge SOC, or also temperature, is calculated. Some battery control strategies are optional, such as SOC allowed range control or strategies where power is limited by SOC and temperature.

Step 105, comparing the calculated current value with the test value.

And step 106, if the current data values of the simulation and the test are matched with each other, executing step 107, otherwise, executing step 108 and returning to step 103 until the simulation and the test data of the current are consistent.

Step 107, it is checked whether all possible vehicle operating conditions have been set, and if so, it means that accurate current data has been obtained for all possible vehicle operating conditions. These current data are provided as inputs to the next stage of analysis, and if not, the process returns to step 102.

And step 108, modifying the vehicle model and returning to the step 103.

The decision flow from 102 to 108 constitutes the vehicle simulation and testing phase. The next phase is the wire simulation and testing phase.

Step 131, setting an ambient temperature and lead parameters, wherein the lead parameters include: geometry, conductor core material, insulator material, conductor core outer diameter, insulator outer diameter, shielding mesh outer diameter, jacket outer diameter, conductor core direct current resistance, shielding layer direct current resistance, conductor core thermal conductivity, conductor core specific heat, insulation layer thermal conductivity, insulation layer specific heat, and the like. These parameters define the heat transfer properties of the wire.

In step 132, the wire diameter is selected from the minimum possible values, and the minimum selectable value of the wire diameter is selected. The current curve data from the previous stage is then injected into a wire thermal simulation model, which is described in FIG. 4.

At the heart of the wire pattern 300 is a finite element analysis numerical simulation model 320, shown in figure 4. In a simple case, 320 consists of an insulating layer 321 and a conductor core 322. The model 320 can be described by a set of equations for heat transfer chemistry, or established by any numerical simulation software. The thermal performance of the wire is determined by the ambient temperature 340 and the wire parameters 350. The latter reflects the heat transfer characteristics of the wire, including wire diameter, geometry, conductor core material, insulation layer material, conductor core outer diameter, insulation layer outer diameter, shielding layer outer diameter, jacket outer diameter, conductor core DC resistance, shielding layer DC resistance, conductor core thermal conductivity, conductor core specific heat, insulation layer thermal conductivity, insulation layer specific heat, and the like. The wire thermal simulation model 320 should be calibrated based on the test data until the simulated output and the actual test output are close to unity. After the wire thermal simulation model is established, the current curve (time function of current) provided by block 310 can be used to simulate the thermal performance of the wire and output the conductor core and insulation surface temperature rise curve (time function of temperature) as described in block 330.

Step 133, using the high-voltage wire current curve as an input of a wire model, performing wire thermal simulation, and obtaining temperature rises of the conductor core and the insulator surface of the wire subjected to simulation test;

and step 134, calculating the temperature rise of the surface of the conductor insulator and the conductor wire core.

And step 135, judging whether the calculated data of the temperature rise and the test data are matched, if not, turning to step 138, and if so, turning to step 136.

And step 136, judging whether the temperature rise of the lead exceeds the limit value in the specification, if so, turning to step 139, and if not, turning to step 137.

In step 137, the current value of the wire diameter is passed to step 151 as the initial design value.

Step 138, modify the wire simulation model and then return to step 134.

Step 139, increase the wire diameter to the next allowable gauge and turn back to step 133.

The decision flow from 131 to 139 constitutes the thermal simulation and testing phase of the wire. The next phase is the vehicle test validation phase.

And 151, making a vehicle test plan, wherein the contents mainly comprise a test standard and a multi-working-condition test sequence.

And 152, modifying the vehicle, making a high-voltage wiring harness sample according to the initial design value of the high-voltage wiring harness obtained in the last stage, assembling the high-voltage wiring harness sample on the vehicle, and simultaneously installing sensors such as a current sensor, a voltage sensor, a thermocouple, a CAN bus interface and the like.

And step 153, the vehicle sequentially completes the test on the chassis dynamometer according to the multi-working-condition test sequence predefined by 151.

Step 154, all data collected by the sensors are collated and analyzed.

Step 155, determine whether the temperature of the lead exceeds the threshold, if yes, go back to step 139, otherwise go to step 156.

Step 156, vehicle tests verify that the initial design of the wire diameter is feasible, and the current wire diameter value is frozen as the final design value.

And step 157, ending.

The present embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation manner and a specific operation process are given, but the scope of the present invention is not limited to the following embodiments.

Claims

1. A method for selecting the wire diameter of a high-voltage electric wire of a hybrid power and electric automobile is characterized by comprising the following steps:

1) establishing a vehicle model, performing electrical load simulation, and obtaining a high-voltage wire current curve, wherein the step 1) comprises the following steps:

101) establishing a vehicle model, setting vehicle running conditions and vehicle parameters, and calculating direct current and alternating current of a high-voltage electrical load;

102) simulating the vehicle model to obtain direct current and alternating current of a high-voltage electrical load of a simulation test;

103) judging whether the calculated value in the step 101) is matched with the test value in the step 102), if so, outputting a high-voltage wire current curve of a simulation test, otherwise, modifying the vehicle model, and returning to the step 101);

2) establishing a conductor model, carrying out conductor thermal simulation according to the current curve of the high-voltage conductor, and obtaining real-time temperature rise data of the high-voltage conductor, wherein the step 2) comprises the following steps:

202) taking the current curve of the high-voltage wire as the input of the wire model, and carrying out wire thermal simulation to obtain the temperature rise of the conductor wire core and the insulator surface of the wire subjected to simulation test;

204) judging whether the test value of the step 202) is matched with the calculated value of the step 203), if so, executing a step 3), otherwise, modifying the wire model, and returning to the step 202);

3) selecting an initial wire diameter according to the real-time temperature rise data of the high-voltage wire, wherein the step 3) comprises the following steps:

judging whether the real-time temperature rise of the high-voltage wire of the simulation test exceeds a limit value, if not, selecting the current wire diameter as the initial wire diameter, if so, increasing the wire diameter and returning to the step 202);

4) judging whether the selected initial wire diameter meets the temperature rise condition and selecting a final design value, wherein the step 4) comprises the following steps:

401) formulating a high-voltage lead sample piece according to the initial lead diameter selected in the step 3), and installing the high-voltage lead sample piece on a vehicle;

402) testing the vehicle and collecting temperature rise data of the high-voltage lead in the test;

403) judging whether the temperature rise data of the high-voltage wire in the step 402) exceeds the limit value, if so, increasing the wire diameter and returning to the step 202), and if not, selecting the wire diameter as the final design value.

2. The hybrid and electric vehicle high voltage electrical conductor wire diameter selection method of claim 1, wherein the vehicle model comprises a driving condition module, a vehicle dynamics module, a mechanical transmission module, a drive motor module, an inverter module, and a battery pack module.

3. The hybrid and electric vehicle high voltage electrical conductor wire diameter selection method of claim 2, wherein the vehicle model further comprises a motor controller module and a battery controller module.

4. The hybrid and electric vehicle high voltage electrical conductor wire diameter selection method of claim 1, wherein the vehicle operating conditions include driving conditions and road grade.