Most transportation industry, including automotive, military, aerospace, and space, have experienced a spike in interest in hybrid and electric vehicle technologies in the last decade. To achieve the promised efficiency and green profile of hybrid and electric cars, it’s vital to undertake driveline and component testing throughout design and manufacture.
Hybrid and electric drivetrains have peculiarities that make testing them distinct from IC-only systems. Hybrid and electric systems employ regenerative braking, which stores electricity in the vehicle’s battery. This needs complicated AC inverters and transmissions.
These cars also contain many module control units (MCUs), tiny onboard computers that regulate the engine, gearbox, and charging system, among others. To test these components, the test system must interact with them through high-speed in-vehicle networks. Changing technology and complexity demand a different, more sophisticated testing approach than IC-only systems.
The technology exists to assure hybrid and electric cars’ energy efficiency. The testing technique reduces operations and maintenance expenses and improves the vehicle’s environmental performance.
Driveline testing for hybrid/EV
During the development of a vehicle, hybrid or electric driveline testing is undertaken at many phases.
Engineers require accurate measurements for testing.
Design engineers need accurate measurements to maximize design efficiency. Otherwise, hybrid/electric technologies will be less beneficial. Most automobiles employ inverter-driven 3-phase AC motors, hence sophisticated power analyzers are required to evaluate 3-phase AC power with high harmonic content. These complicated test systems have numerous aspects to be tested and coordinated.
Manufacturers check performance and safety via in-process and end-of-line testing.
End-of-line testing is conducted to ensure no manufacturing faults were introduced and that components will work as expected. Typical tests include operational validation, fast performance testing, and thorough testing to ensure high-voltage electrical systems are safely separated in cars.
In-process testing is also used to test production-line component assemblies. This enhances production productivity and minimizes the likelihood of incorrect components in the final product.
Motor users examine incoming merchandise for faults.
A proportion of components are tested for quality control (QC) to ensure they work as expected and are defect-free. A forklift firm may QC test imported electric motors for its forklifts. They’d utilize QC testing to make sure their supplier’s cargo functions as expected and won’t fail often in the field. This sort of test system is less sophisticated since it doesn’t measure as many elements nor as accurately as engineering systems.
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Hybrid or electric cars employ 4-quadrant motor/inverter technology to help or replace the engine (electric vehicle). Four quadrant indicates the motor may accelerate, run, and decelerate forward or backward.
During deceleration, the system employs regenerative braking, so the electric motor slows the car and becomes a generator, returning energy to the battery. In hybrid systems, the engine is usually off while stopping, slowing down, or idling. The electric motor becomes a generator and partly recharges the battery. To keep going or accelerate, the engine is restarted. During acceleration, the electric motor uses recovered energy to minimize engine load and fuel consumption.
Recaptured electricity allows us to run longer between fillups and/or charges, improving fuel efficiency. The testing procedure used to develop and manufacture automobiles must guarantee the engine runs efficiently and uses regenerative power effectively.
Hybrid/electric vehicle testing
Traditional internal combustion engine testing evaluates speed, torque, temperatures, pressures, and flows. Internal combustion engine testing (e.g., water brake and eddy current) does not need precise control of speed and torque, hence these dynamometers cannot test hybrid or electric powertrains’ regenerative (motoring) modes of operation.
Modern hybrid/EV test systems must be able to test high-power regenerative electrical drives, high voltage battery and charging systems, and any number of smart control modules (MCUs).
System testing
For bigger hybrid/electric drivetrains, high-voltage, high-efficiency drive systems are trending. From 12/24-volt DC to 240-volt AC, one-eighth or less of the electricity is needed to produce the same power. This is more efficient and needs lesser wiring and components to transmit energy, resulting in smaller, lighter, more energy-efficient automobiles. Current designs use 800 volts or more, making cars more efficient.
For this sort of testing, a 4-quadrant driving dynamometer is needed to simulate/test all hybrid or electric vehicle operating modes. Testing a system that functions in this way requires the ability to drive or load in either direction. A typical dynamometer can’t test a regenerative braking system.
High-efficiency AC systems employ three-phase inverters to accurately regulate the electric motor(s). These systems are incredibly efficient but produce a lot of harmonic distortion. A contemporary hybrid/EV test equipment also incorporates a powerful three-phase power analyser. This device must properly measure high-power electrical values with harmonic distortion.
SAKOR developed HybriDyne to thoroughly evaluate hybrid and electric vehicle drive systems, including electrical assist (parallel hybrid), diesel-electric (serial hybrid), and all-electric vehicle systems.
The HybriDyne incorporates SAKOR’s DynoLAB powertrain data collecting and control technologies. HybriDyne can test individual mechanical and/or electrical components, integrated sub-assemblies, and full drivetrains using a single system.
Simulation of high-voltage batteries
High-voltage batteries and charging systems are crucial to current hybrid and electric cars. To test a high-voltage hybrid or electric powertrain, you need precise, repeatable DC power. Since battery performance varies with charge status, ambient conditions, and age, they aren’t suitable for powering hybrid/EV test system DC components. Reliable DC power is needed for repeated outcomes. A normal power supply can’t absorb power from the regenerative system. Standard power supplies used with regenerative systems may be damaged.
SAKOR addressed this difficulty by designing a Solid State Battery Simulator/Test System to test high-voltage hybrid car batteries.
High-efficiency, line-regenerative DC power supplies the system. During regenerative modes, absorbed power is returned to the AC mains instead of being wasted as heat, as in older testing systems. This technology improves electricity efficiency and saves running expenses.
Coupled with the DynoLAB, the Solid State Battery Simulator/Tester precisely replicates high-voltage battery reaction. Its reproducible findings are due to its constant charge state. When used as a battery tester, this identical equipment simulates a vehicle’s charge/discharge profile on a road course.
When utilizing an AC dynamometer with a regenerative DC power supply, the power absorbed by one unit may be recirculated to the other. This decreases AC mains power by 85% to 90%, reducing overall operating costs. This energy-efficient structure may readily pay for itself throughout the test system’s life. Low maintenance also reduces operational expenses.
Modules’ communication
Hybrid or electric vehicle testing systems must have MCU communication. Throttle and ignition formerly controlled the engine. Now, engines have an engine control unit (ECU), and the car will likely have a separate MCU that regulates the electric drive. These units send orders and/or data through CAN, LIN, FlexRay, etc.
To evaluate this complicated drivetrain layout, the test system must interact effectively with these control components. DynoLAB integrates these distinct devices into a single test platform.
Hybrid and electric vehicles offer enhanced environmental performance in the automotive, heavy equipment, military, and aerospace sectors. To fulfill this promise, driveline testing programs must adapt to new technologies.
