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(Uni) DT021/TU821 Electric Car (Week 5)

Electric Car Tractive System

TUDAUTHOR NAME: Jerico M.               STUDENT NUMBER: C15580367                COURSE: DT021A/TU821      

Week 5 Objectives

basgsagdsagdsagadsgdsagsadgdsagasgsadgdsagsadgasadgasgdsagsadgadsgasgaThe goal of this week is to start the implementation of the instrumentation of sensors around the EV, this involves co-ordination with the mechanical students working on other sensors such as speed, steering, braking, etc… along with other signals that we will be using such as the BMS temperature, voltage and current measurements over CAN bus.

  1. Attend meeting with supervisors: Monday 24/02/20
  2. Obtain the EMUS G1 BMS CAN bus IDs from Michael
  3. Get updates for the speed sensors from Lowry
  4. Start implementation of the LA 205-S hall-effect current sensors using the Arduino
  5. Start rewiring of the LVCSS to the new case
  6. Spec hall-effect current sensors for bidirectional use for regenerative mode
  7. Work at Bolton Street workshop: Friday 28/02/20

Overall Project Progress

asgsagdsagdsagadsgdsagsadgdsagasgsadgdsagsadgasadgasgdsagsadgadsgasgasOver the week the most important parts were to talk to certain students on the mechanical side, mainly Lowry for the speed sensor and Michael for the BMS measurements, along with finally starting the rewiring of the LVCSS.

Supervisor Meeting Summary (Week 5)

After meeting with supervisors the objectives for the project have been laid out for the coming weeks. In terms of the overall project, the following objectives must be addressed this week and the next few weeks.

Objectives for the next few weeks

  • Start the rewiring of the LVCSS, this includes:
    • Obtaining cable IDs from the technicians
    • Creating a colour-code scheme for the cables
    • Improve cable management and component positioning on the LVCSS
    • Fit it to the new case and make necessary rearrangements
    • Get rid of fault points by getting rid of the grey connectors or obtaining more secure connectors as they will be needed for maintenance
  • Getting an update from Lowry to see his progress with the other sensors on the EV:
    • Speed sensor
    • Steering position sensor
    • Brake position sensor
  • Getting an update from Michael on the BMS measurements over CAN including:
    • BMS temperature measurements CAN ID
    • BMS voltage measurements CAN ID
    • BMS current measurements CAN ID
  • Start instrumentation on the EV by first researching, then implementing it through an Arduino for CAN bus communication the following:
    • Motor current measurements (LA 205-S)
    • Motor voltage measurements (LA 205-S)
    • BMS measurements as mentioned above:
      • BMS temperature measurements (BMS Cell Modules)
      • BMS voltage measurements (BMS Cell Modules)
      • BMS current measurements (G1 Close Loop Dual Range Current Sensor)

Objectives for long-term and thesis research

Moving on to the long term objectives of the projects, research on additional objectives have also been laid out depending on how the EV progresses, this includes the following:

  • Research how fast the transient characteristics of the TS can be caught
  • Research on the sample rates of the Arduino, if the data from drives/motor LA 205-S sensors can be logged on to an SD card for monitoring purposes
  • Research on energy that is being used up in the EV to see how regenerative braking can be implemented, its efficiency if implemented and how it could be implemented for next year projects

Overall Project Plan

The deadline for the objective of rewiring the LVCSS has already been set out by supervisors as shown below in Figure 1, which is due around the 13th of March. On the side as mentioned earlier, the starting the implementation of the sensors around the vehicle will begin this week, for example milestones for the following include: The LA 205-S current sensors for the motors tested via Arduino then over CAN bus and BMS current, voltage and temperature readings, all being sent over CAN bus to the main SCADA system.

After meeting with supervisors on Monday 24/02/20 and some of the mechanical students on Friday 28/02/20, the project plan was adjusted with the guidance of supervisors as mentioned previously and also had to be further updated as issues of high priority regarding the speed sensors have arose, which will be discussed in more detail later in this blog.

Week 5 Project Plan

Figure 1: Project Plan for the Next Three Weeks (Week 5)

EV Tractive System & LVCSS Progress

asgsagdsagdsagadsgdsagsadgdsagasgsadgdsagsadgasadgasgdsagsadgadsgasgasThe main objectives for this week and the coming weeks will be to start rewiring the LVCSS before the given deadline on Friday 13/03/20 for the overall EV tasks that have to be done as part of being the ESA & ESO for the formula team, in addition to the specific goals of my own project, I will also be starting the instrumentation of the EV cars, this includes having the speed sensor, BMS sensors, motor and drive sensors sending measurements over CAN bus via Arduino.

LVCSS Component Layout Plan for the New Case

With the co-ordination of the mechanical student Sean and other students Raimonds and Niall, a lot of progress has been made in terms of installing the LVCSS from the old case to the new case. Improvements regarding the components of the LVCSS were carried out for this week as there are issues due to space constraints in the new case because on the old case, the following main component layout can be seen below in Figure 2:

Week 5 Component Rearranged (Before)

Figure 2: LVCSS Original Component Layout

From Figure 2, all of the grey spaces on the main board are filled up with several cables on the physical system, making it difficult to track where cables from each wire even goes to, in addition it can be seen that there were also other relays that weren’t even installed on to the main board, for example the Ready to Drive Relay and TSAL Relay. Thus after spending hours planning an improved layout of the components, the following main changes we agreed to make were to:

  • Installing all relays into the same part of the main board to allow for easier cable management, better component organization and easier to track cables to each relay during maintenance.
  • Move fuse & fuse connections beside the relay connection points at the bottom of the main board for the same purpose as mentioned above for the relays.
  • Replacing the Arduino UNO on the board with an Arduino NANO to create more space for other components.
  • Order a mount for the Arduino NANO so it can be installed into the main board.
  • Make all appropriate drilled holes for installation around the board, obtain all required screws & bolts before making component layout changes.

After agreeing to these changes, the new layout can be seen below in Figure 3, where we have already successfully made the necessary work to install the relays, fuses, in addition a mount for the Arduino NANO has also been ordered and the brake position sensor and relay code from the UNO has also been obtained so that it can simply be used for the NANO.

Week 5 Component Rearranged (After)

Figure 3: LVCSS Updated Component Layout

Battery Management System (BMS) CAN IDs

After talking to Michael who is doing his project on the BMS, obtaining the CAN IDs from him has been postponed as he does not know what IDs the BMS is actually using for the temperature and voltage measurements, also he does not have the hall-effect current sensor installed yet, so for now the BMS CAN IDs will have to be given dummy IDs when designing the CAN ID priority structure for the entire CAN bus communication system of the EV.

LEM LA 205-S Hall-effect Current Sensor

After initial research into the LA 205-S current sensors, the following pin layout shown in Figure 4 was obtained for the sensor, with the following connections for both the sensor and the Arduino:

  1. Cable being measured through the LA-205S sensor.
  2. Variable resistor connection on Pin 2 based on the resistance needed for the cable being measured.
  3. 12V to 15V supply across Pin 1 and Pin 3 of the LA-205S sensor.
  4. Pin 2 of the LA-205S sensor to an Analog Pin of the Arduino for measurements.
  5. Pin 4 of the LA-205S sensor unconnected.
  6. 5V supplied via USB connection from a computer to the Arduino.
  7. DC to DC converter since Arduino is 5V and LA-205S sensor is 12V to 15V.
LEM SPECS

Figure 4: LEM LA 205-S Hall-effect Current Sensor Pin Layout

With an idea of how to implement the sensor with the Arduino researched, this will be tested next week starting  Monday 02/03 and expected to have it working by Friday 06/03 as shown in the updated project plan in Figure 1.

Speed Sensor

After finally talking to Lowry, updates on the speed sensor were discussed, I finally found out which sensors will be used, which is the SR17C-J7 hall-effect speed sensor. With the sensor present at the lab, we were able to successfully test the sensor for speed measurements using the Arduino, although there were issues that we needed to find out which are:

  • To find out the max frequency of the sensor, so Lowry knows how to design the gear disc that will be used with the sensor.
  • To find out if the Arduino is capable of measuring the measured data to measure the speed or if timers have to be used because the Arduino might not be able to handle the large amount of data form the sensor, although if timers are used it gives very inaccurate readings at low speeds.

Although at the end of Friday 28/02/20, an issue came up regarding the speed sensors due to the way the sensor is designed as shown in Figure 5. The problem with this sensor design is the way it requires space on both sides of the gear disk in order to measure the speed, while there is only space on one side on the physical wheel system of the EV, this is urgent as the type of sensor needs to be known by Monday 02/03/20 since it determines the disk design and other modifications which takes a long time to be made by the mechanical engineers.

Week 5 Speed Sensor SR17C-J6 Sensor Design.JPG

Figure 5: SR17C-J6 Speed Sensor Design

With this issue, I was tasked to spec a speed sensor with a design shown in Figure 6, since this sensor can easily be mounted on one side of the gear disk to measure the speed. Since it takes a long time to modify parts and manufacture the disk, obtaining a new speed sensor is of high priority, thus the project plan in Figure 1 needs to be changed to adjust to the development of the EV.

Week 5 Speed Sensor Needed Design.JPG

Figure 6: Desired Speed Sensor Design

Week 5 Objectives Checklist

asgsagdsagdsagadsgdsagsadgdsagasgsadgdsagsadgasadgasgdsagsadgadsgasgasRed = Incomplete               Green = Complete

  1. Attend meeting with supervisors: Monday 24/02
  2. Obtain the EMUS G1 BMS CAN bus IDs from Michael (Michael does not know the BMS CAN IDs being used for temperature and voltage measurements)
  3. Get updates for the speed sensors from Lowry (New issues such as spec for a speed sensor is needed by Monday 02/03)
  4. Start implementation of the LA 205-S hall-effect current sensors using the Arduino
  5. Start rewiring of the LVCSS to the new case
  6. Spec hall-effect current sensors for bidirectional use for regenerative mode
  7. Work at Bolton Street workshop: Friday 28/02

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