**2. Power semiconductor module in HEV/EV**

**1. Introduction**

24 Modeling and Simulation for Electric Vehicle Applications

research and development [1].

During the lastfew decades, people have made great efforts on exploiting sustainable andclean energy to mitigate the global crisis of fossil energy and deterioration of environment. Accord‐ ingly, the application systems powered by new and clean energy are developed with high interests. One of the crucial systems is hybrid and electric vehicles (HEV/EVs), which rely fully orpartlyonelectricitywhichtransformedfromrenewable andcleanenergysuchas solar,wind, and nuclear powers. Therefore, HEV/EV is regarded as environmental-friendly product for the reduction of CO2 and noise remarkably. Furthermore, the development of HEV/EV is becom‐ ingamainpolicyofmostgovernmentsandautomotiveindustry,leadingtoworldwideextensive

**Performance Temp Reliability Efficiency Size/weight Cost** Power device High *T*jmax **√ √ √ √**

> Direct cooling **√ √ √** Planar contact **√ √ √ √**

> New housing **√ √ √**

HEV has dual power sources of internal combustion engine and electric motor, while EV uses electric motor to power only. In both cases, the electric motor is essential to the systems. The motor, on the other hand, acts as a generator for regenerative breaking. The importance of motor in HEV/EV results in high-level significance of power-train system of which the main element is DV/AC inverter. The inverter controls power conversion from battery to motor by power semiconductor devices. Therefore, the core component in the power system of HEV/EV is power semiconductor switches, which are normally insulated gate bipolar transistor (IGBT) and free-wheeling diode (FWD) at the moment [2]. For increasing power, reliability, and prolonging lifetime, IGBT and FWD chips are packaged to module with

The great interest of developing HEV/EV across the world has motivated massive effort on improving and optimizing automotive modules. These modules always work in harsh environment of high temperature, humidity, mechanical vibration, and shock, and the possibility of chemical contamination. As limited by the space and weight in HEV/EV system,

Module packaging Low *R*th **√ √ √**

Ultrasonic welding **√** New interconnection **√ √**

**Table 1.** Dependence of IGBT module performance on power device and assembly.

multiple devices, isolation layer, and protection parts [2–9].

Low *R*, *L* **√ √ √**

Low loss **√ √ √ √ √**

No base **√ √ √**

It is expected that the HEV/EV will be one of the strong growth points for automotive industry in the next few decades with the improvement of performance, evolvement of technologies, and reduction of cost of ownership [1]. **Figure 1** shows the annual light-duty vehicle sales prediction by technology type. Based on Energy Technology Perspectives forecast, EV, Plugin HEV (PHEV), and HEV will reach sales of 2.5, 5.0, and 10.0 M, respectively, per year by 2020, making the total sales of low carbon vehicles about 18% of the annual sales. By 2030, EV, PHEV, and HEV are expected to sell 9, 25, and 26 M units, respectively, corresponding to 50% of annual automotive market. And by 2050, sales of all kinds of low carbon vehicles will occupy more than 80% of the whole automotive sales [1]. Yole Development suggests that about 25 M cars manufactured will be electrified in 2016, with the majority of them being micro-HEV with low level of electrification, and 5 M will be full HEV, PHEV or EV [16].

With rapid ramp-up sales of HEV/EV in the last decade, power semiconductor industry has seen huge opportunity of power components and system supply. DC/AC inverter market will grow from \$45 bn in 2012 to \$71 bn in 2020 with more than 28 M units of 2012 and 80 M in 2020 [17]. HEV/EV represents one of the biggest markets for power device and system manufac‐ turers together with the other most attractive motion and conversion applications of photo‐ voltaics (PVs), wind turbines, rail traction, motor drives, and uninterruptible power supplies (UPSs) [17].

**Figure 1.** Annual light-duty vehicle sales by technology type, source: IEA 2010.

Power electronics is one of the essential technologies in HEV/EV research and development. The electricity for driving HEV/EV from grid is needed to be converted a few times before reaching electric motor and accessory appliances. These procedures are controlled by power electronic systems of which the main components are power IGBT modules [4, 5, 9]. **Fig‐ ure 2** shows the schematic of power-train system in the EV showing the power control systems of converters and inverters. For HEV, the battery could be charged by both the electric grid and the internal combustion engine.

**Figure 2.** Schematic of power train in the EV.

Power modules are the core parts of inverter and converter systems in **Figure 2**, which dominate the system performance, reliability, size, weight, and the cost. **Figure 3** is an example of an inverter cost breakdown, showing that power module accounts for 30% of the whole cost and its cost reduction is critical to the system. To save size and weight of power systems, the cooling technology and system must be improved as it accounts for about 15% of cost and 30% of weight of the whole system. In 2012, the market was \$1.9 bn for power modules which were mostly made with IGBT. At the moment, the average cost of a power module is above \$500 in HEV, making a few billions of market in the next few years [17].

**Figure 3.** Cost breakdown of an HEV/EV inverter.

In HEV/EV application, the work environment of power system and module is harsh than industry applications. For example, the ambient temperature under the hood may reach 100°C with higher humidity; the HEV manufacturer is looking for sharing engine coolant with power module so the coolant temperature will be up to 105°C; the mechanical vibration and shock are usually strong and unpredictable during the vehicle running. In addition, the reliability, size, weight, and cost are challenges to power module development as the limited space and cost objectives of HEV/EV [9, 10–13]. **Table 2** shows the technology targets for both the power electronics and electric motors in HEV/EV [15].


**Table 2.** Technology targets for HEV/EV.

**Figure 1.** Annual light-duty vehicle sales by technology type, source: IEA 2010.

HEV, making a few billions of market in the next few years [17].

and the internal combustion engine.

26 Modeling and Simulation for Electric Vehicle Applications

**Figure 2.** Schematic of power train in the EV.

**Figure 3.** Cost breakdown of an HEV/EV inverter.

Power electronics is one of the essential technologies in HEV/EV research and development. The electricity for driving HEV/EV from grid is needed to be converted a few times before reaching electric motor and accessory appliances. These procedures are controlled by power electronic systems of which the main components are power IGBT modules [4, 5, 9]. **Fig‐ ure 2** shows the schematic of power-train system in the EV showing the power control systems of converters and inverters. For HEV, the battery could be charged by both the electric grid

Power modules are the core parts of inverter and converter systems in **Figure 2**, which dominate the system performance, reliability, size, weight, and the cost. **Figure 3** is an example of an inverter cost breakdown, showing that power module accounts for 30% of the whole cost and its cost reduction is critical to the system. To save size and weight of power systems, the cooling technology and system must be improved as it accounts for about 15% of cost and 30% of weight of the whole system. In 2012, the market was \$1.9 bn for power modules which were mostly made with IGBT. At the moment, the average cost of a power module is above \$500 in The major criteria for evaluating an automotive power module such as the performance, efficiency, reliability, cost, and volume/weight are generally determined by power semicon‐ ductor devices, packaging, and manufacturing technology. These criteria can be characterized by a series of technical parameters in aspects of the power module's electrical, thermal, thermomechanical, and mechanical properties, as well as packaging materials and processing techniques. The parameters determining the overall performance of a power module are thermal impedance (resistance and capacitance), operating and maximum junction tempera‐ ture (*T*j op, *T*jmax), parasitic resistance and inductance, power cycling, thermal cycling/shock, vibration ruggedness, etc. [2–13]. People have made numerous technical advancements to improve these parameters through material and processing development and package structure optimization. **Table 1** lists the potential available solutions to meet the challenges of automotive packaging in the aspects of power semiconductor devices, and power modules packaging. It is supposed that improvement in one technology area is not sufficient at all to overcome all the difficulties and a comprehensive approach is required, and it may be not possible to achieve all the market and technical goals by making improvement to the existing technologies.
