Absolutely, establishing complete electric drive systems before installation is a critical step in the electric vehicle (EV) conversion process. This approach ensures that all components are functioning correctly and are compatible with each other before being integrated into the vehicle. At GMT-CMVTE, complete electric drive systems are assembled in the workshop before being installed in the engine-free vehicle.
Converting the Conventional Vehicles to Electric Vehicles
In an EV conversion, it’s crucial to first establish and test the complete wiring to ensure all components are properly connected and functioning. Converting a conventional vehicle to an EV involves several key steps, including wiring and integrating the complete EV drive system.
Here’s a general guide to help you understand the process:
Step 1: Research and Planning
- Select a Donor Car: Choose a vehicle that is suitable for conversion. Factors to consider include weight, aerodynamics, and available space for batteries and electric components.
- Gather Components: You’ll need an electric motor, motor controller, batteries, charger, and auxiliary components like power steering and air conditioning systems.
Step 2: Remove Internal Combustion Engine (ICE) Components
- Strip Out ICE Components: Remove the engine, fuel tank, exhaust system, and radiator. Depending on your conversion, you might also need to remove the transmission and drivetrain components.
Step 3: Select Electric Components
- With the ICE components removed, it’s time to select the electric components for your conversion.
- This typically includes an electric motor, motor controller, batteries, charger, and auxiliary components such as power steering and air conditioning systems.
- You can choose from a variety of electric motors, ranging from DC brushed motors to AC induction motors, depending on your performance requirements and budget.
Step 4: Install Electric Components
- Mount the Electric Motor: Install the electric motor in place of the removed ICE. Connect it to the transmission or directly to the wheels.
- Install the Motor Controller: This regulates power delivery to the motor.
- Place the Batteries: Strategically place the batteries throughout the vehicle, considering weight distribution and available space.
Step 5: Wiring and Integration
- Route and Connect Wiring: Carefully route and connect the wiring harnesses for the electric motor, controller, batteries, charger, and auxiliary systems. Ensure all connections are secure and properly insulated to prevent electrical faults or shorts.
- Integrate with Existing Systems: Connect the electric components with the vehicle’s existing systems, such as brakes, steering, and instrumentation.
Step 6: Testing and Debugging
- Thorough Testing: Before hitting the road, thoroughly test and debug your EV conversion. Check for proper operation of the electric motor, controller, and auxiliary systems.
- Check for proper operation of the electric motor, controller, and auxiliary systems. Test the vehicle’s performance, including acceleration, braking, and handling.
- Address any issues or discrepancies that arise during testing to ensure the safety and reliability of your electric vehicle.
Step 7: Finalization and Refinement
- Once testing is complete, finalize your EV conversion by making any necessary adjustments or refinements.
- Fine-tune the motor controller settings for optimal performance and efficiency. Consider adding additional features or upgrades, such as regenerative braking or onboard telemetry.
- Finally, give your electric vehicle a fresh coat of paint or personalized decals to make it truly your own.
Wiring, Connecting, and Operating a Complete Electric Drive System in GMT-CMVTE for EV Conversion
- Understanding the Complete Electric Vehicle Drive System
Electric vehicles are revolutionizing the automotive industry, offering a cleaner and more sustainable alternative to traditional ICE vehicles. At the heart of every EV is its drive system, which is responsible for converting electrical energy from the battery into mechanical power to drive the wheels. Let’s dive into the key components and workings of a complete electric vehicle drive system.
The complete EV drive system is composed of two Li-ion battery packs each one has105Ah, 163V to drive high voltage 50kW PMSM for EV Conversion in GMT-CMVTE.
- Key Components of an EV Drive System
- Battery Pack
The battery pack is the primary source of energy for an EV. It stores electrical energy that powers the electric motor and other vehicle systems. Modern EVs typically use lithium-ion batteries due to their high energy density and long lifespan. Li-ion battery pack has 51cells, 105Ah, 163.2V battery pack used in GMT. Two of then are connected in series to get the output voltage of 326.4V. In this GMT, Power Distribution Unit (PDU) is used to manage the power from the two battery packs for EV Conversion.
2, Electric Motor in GMT
The electric motor converts electrical energy from the battery into mechanical power. Unlike ICEs, electric motors deliver instant torque, providing quick acceleration and a smooth driving experience. Common types of electric motors used in EVs include induction motors and permanent magnet synchronous motors. The test has been performed to drive 50kW PMSM with maximum restricted power of 100kW.
3, Power Electronics
Power electronics manage the flow of electrical energy between the battery and the electric motor. This includes components like inverters, which convert the direct current (DC) from the battery into alternating current (AC) for the motor, and converters, which adjust voltage levels as needed.
- Three-phase Voltage Source Inverter
The PMSM-inverter system is adopted in this test. In this system, the controller calculates the switching signals according to the expected voltages, and the inverter can output the corresponding voltage pulses based on the switching signals; then these voltage pulses are applied to the motor windings to generate continuous state currents.
Electric vehicle drive with a PMSM motor
- DC-DC Converter in GMT
The DC-DC converter is used in EVs for charging the 12V Lead-acid battery. The following is a picture during work in GMT for EV conversion. The 12V battery is charging with 35.5 A. This current depends on the high and low voltages, and on the internal resistance of the loop. In this test, the used DC-DC converter steps down the high-voltage battery of 326.4V in EVs to 13.8V for charging the 12 lead-acid battery.
- On-board Battery Charger (OBC) in GMT
RA6P6 series on-board charger is a high-power density and high-efficiency charger specially developed for new energy vehicles such as new lithium-ion pure electric vehicles and logistics vehicles. The module is 90-265VAC AC input, and the DC output voltage is adjustable in the full range. In the test, a 6 kW, 360V,18A, air-cooled on-board AC-DC charger are used during charging test in GMT.
4,Controller
The controller acts as the brain of the EV drive system. It regulates the power flow from the battery to the motor based on driver inputs, such as acceleration and braking. The controller ensures optimal performance and efficiency of the drive system.
- Motor Control Unit (MCU) in GMT
Testing the inverter and controller for a 50kW electric drive system is a crucial step in ensuring the reliability and efficiency of the EV conversion. Here, inverter and controller for 50kW for EV Conversion in GMT-CMVTE has been wired and tested.
Using vector control in Permanent Magnet Synchronous Motor (PMSM) drive systems is a highly effective method for EV drives. It allows for precise control of the motor’s torque and speed, which is crucial for the performance and efficiency of electric vehicles.
Key Aspects of Vector Control in PMSM Drive Systems
- Vector Control Method:
- Field-Oriented Control (FOC): This method decouples the torque and flux control, allowing for independent control of the motor’s magnetic field and torque production.
- High Efficiency: Vector control improves the efficiency and dynamic performance of the motor, making it ideal for EV applications.
- Multi-Control Modes:
- Torque Control Mode: This mode allows the driver to control the torque output of the motor directly. It’s useful for applications where precise torque control is needed, such as in acceleration and deceleration.
- Speed Control Mode: This mode allows the driver to set a desired speed, and the system adjusts the torque to maintain that speed. It’s ideal for maintaining consistent speeds, such as during highway driving.
Implementation in EV Conversion
- Programming and Selection: The ability to switch between torque control mode and speed control mode provides flexibility in driving conditions. This can be programmed into the vehicle’s control system, allowing the driver to choose the most appropriate mode for their needs.
- Testing and Validation: Both control modes should be thoroughly tested to ensure they perform as expected under various driving conditions. This includes testing for responsiveness, stability, and efficiency.
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- Vehicle Control Unit (VCU) in GMT
The Brain Behind EVs: The Role of a Vehicle Control Unit
In this blog, we explore the critical role of Vehicle Control Units (VCUs) in the EV powertrain. As the central management systems within EVs, VCUs oversee and regulate essential functions like motor management, battery supervision, and energy efficiency.
Technical features:
- Built-in 3-way CAN bus for communication with other modules.
- Protection features: provide overvoltage, overcurrent and power reverse connection protection.
- With multi-channel digital input/output, analog input/output, PWM output, and PT100 temperature detection interface.
- With various power output: including 24V, 5V, 15V power supply.
- It has the functions of real-time monitoring, fault alarm, diagnosis and debugging of the host computer.
Vehicle Control Unit (VCU) for 50kW PMSM for EV Conversion in GMT-CMVTE
- 5, Transmission
- While many EVs use a single-speed transmission due to the wide torque range of electric motors, some high-performance models may incorporate multi-speed transmissions to enhance efficiency and performance at different speeds.
- 6, Thermal Management System
- Managing the temperature of the battery, motor, and power electronics is crucial for maintaining performance and longevity. Thermal management systems use liquid or air cooling to keep components within their optimal temperature range.
Communication Between MCU, VCU, BMS, OBC Charger and other Peripheral Equipment
- Controller Area Network (CAN)
The CAN bus allows microcontrollers and devices to communicate with each other within the vehicle without a host computer. It is known for its robustness and error-handling capabilities, making it suitable for critical applications like controlling the electric motor or battery system. Through CAN messages, the VCU can send commands to the traction inverter to adjust the speed and torque of the motor, request battery status updates, and receive data from various sensors. It is important to note that while the VCU doesn’t directly control the torque and power delivered to the motor, it calculates and commands what is needed based on driver input and vehicle status. The traction inverter then translates these commands into action, adjusting the motor’s operation accordingly.
- How the CAN Communication Circuit Works
- Data Transmission: The CAN bus uses a differential signalling method with two wires, CAN High (CAN-H) and CAN Low (CAN-L), to transmit data. This method helps in reducing electrical noise and ensuring data integrity.
- Message Prioritization: Each message on the CAN bus has a unique identifier that determines its priority. If multiple messages are sent simultaneously, the message with the highest priority is transmitted first, ensuring critical data is communicated promptly.
- Real-time Monitoring: The CAN bus enables real-time monitoring and control of the charging process. For instance, the OBC can communicate with the BMS to adjust the charging rate based on the battery’s state of charge (SoC), temperature, and voltage.
- Error Detection and Handling: The CAN protocol includes error detection mechanisms to ensure reliable communication. If an error is detected, the faulty message is retransmitted, and the source of the error is identified and isolated.
