Mild Hybrid Testing

Task

The aim of mild hybrid systems is to support the combustion engine in operating points in which the latter is comparatively inefficient. These systems are a compromise between an improvement of fuel efficiency and a minimization of conceptual changes to the vehicle body that are required for full hybrid drives.

Based on 48 V systems, automotive suppliers are developing electric motors that are designed as integrated motor starter generators (MSGs) and coupled to the internal combustion engine. This innovative drive component facilitates four additional functions within the existing system: brake energy recuperation, torque support during start-up, an especially comfortable start-stop control, and energy-efficient coasting.  

Challenge

Mild hybrid electric vehicle controllers require an innovative test system for validating these complex functions.

Combining the option of full-power testing in a virtual environment requires a laboratory setup that can represent the highly dynamic effects of electric machines. For most realistic emulation, PWM effects also need to be simulated precisely. This requires extremely short cycle times for all involved components and interfaces. To also test the environmental effects like cold-starts or extreme temperatures, the surrounding conditioning needs to be controlled as well. 

Solution

Testing mild hybrid drives is a typical application for the dSPACE test systems based on DS5381 low-voltage electronic load units.

The example configuration described here is a mild-hybrid test system that is designed for power hardware-in-the-loop testing of a 48 V starter/generator unit with a phase current of 1,200 A. In this test system, 12 low-voltage electronic load units are connected in parallel to achieve the required system power. The ECU is located in a separate climate chamber and is connected to the HIL test system using custom specific mapping cabinet and harness. To provide the most realistic motor emulation possible, a user-programmable FPGA board from dSPACE is integrated into the test setup. This FPGA board computes the model of the permanent magnet synchronous motor (PMSM), which is included in the dSPACE XSG Electric Components library. The board also provides the required low-latency interfaces to the load modules. This model-based approach lets you change motor parameters or even motor types during run time with just a few clicks and without any hardware modifications. To close all control loops, the test system is also equipped with communication protocols and position sensor simulation interfaces. The climate chamber allows for conditioning of the device under test (DUT) according to customer requirements.

Basic Information

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