*2.1. HEB Architecture*

The object of this research is derived from the first Chinese HEB—a tracked vehicle that has a series hybrid powertrain and a hydraulic operating system. Its architecture schematic diagram can be seen in Figure 1. This powertrain adopts double wheel-side motors to drive tracks on both sides, enabling the HEB to achieve center-based steering. The drive system employs a typical alternating current(AC)-direct current (DC)-AC transmission form to convert mechanical energy into electrical energy and then mechanical energy. The blade operating system is driven by the hydraulic pump, whose power comes from the engine and flows through the transfer case. Table 2 gives the main specifications of the HEB.

**Figure 1.** Schematic diagram of the hybrid electric bulldozer (HEB) architecture.


