High Power Electrical Systems

This product is a highly integrated Mechatronics product consisting of mechanical, electromagnetic, and electromechanical components and subsystems of a car modeled based on 42V technology. The product enables users to perform simulation, and analysis of components and subsystems of a dual voltage system.

Note: Generic products with similar functionalities are available on the market for up to 100k per copy. This product is, however, much more specific compared to generic products and when 42v becomes the auto industry standard; it has the potential of becoming Mechatronics Inc. number one product.

Using MAST, Saber Simulation Environment modeling language, models for all components used in the dual-voltage system are developed, e.g., the alternator, batteries, DC/DC converter, and loads. By simulating the system, the flow of power through the system was monitored as the power supply and demand changes with vehicle speed changes (drive-cycle) and load on-off transitions (load-cycle). The simulation results, and in particular, the final battery state of charge at the end of each transient analysis, were then used to make judgments regarding the sizing of the power supply components

The basic dual-voltage system consists of two buses; one supplied by the existing standard 12V battery and regulated at 14V, and the other supplied by a 36V battery and regulated at 42V. All high-power loads are located on the 42V bus. All low-power loads are placed on the 14V bus. Two scenarios have been analyzed; dual/single alternator systems.

• Dual Alternator System; is based on two alternators providing both high (42V) and low (14V) voltage outputs.

Figure 1 Saber design of dual alternator system

• Single Alternator System; is based on one alternator providing high (42V) voltage output. The lower voltage (14V) is derived from the high voltage bus by use of a dc/dc converter.

Figure 2 Saber design of single alternator system with DC/DC converter

To evaluate the power flow in the dual-voltage system, the system’s supply and demand of power under typical driving conditions needed to be simulated. This required the use of two types of data: drive-cycles or engine speed profile and load-cycles. The length of the engine speed profile used is 800 seconds. A number of standard and non-standard drive-cycles exist and are used in the industry. Table 1 lists each drive-cycle used in this product and a brief description of each.

Table 1 Drive-cycles used in simulations

Figure 3 below shows two typical drive-cycles (CLCC summer and winter, respectively), the engine speed in revolutions per minute plotted against time in seconds. Engine idle speed is 850 rpm for summer and 700 rpm for winter. Engine speed for Country Night Load (CNL) is 2752 rpm.

Figure 3 City Load Carrying Capacity engine speed profiles used in dual alternator system (in summer and winter)

Besides specifying the car’s speed, which determines the amount of power that can be supplied to the system by the alternator, it is also necessary to specify the sequence of load events, which will demand power from the electrical system.

Figure 4 (14 volts) and Figure 5 (42 volts) show alternator currents and bus voltages for CNL drive-cycle for the dual alternator system.

Figure 4 (14 volts) bus voltage and alternator current for 14 volts alternator (CNL)

Figure 5 (42 volts) bus voltage and alternator current for 42 volts alternator (CNL)

Figure 6 (14 volts) and Figure 7 (42 volts) show DC/DC converter and alternator currents and bus voltages for CNL drive-cycle for the single alternator system.

Figure 6 (14 volts) bus voltage and current for DC/DC converter (14 volts side) (CNL)

Figure 7 (42 volts) bus voltage and alternator current for 42 volts alternator (CNL)

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