Electric Vehicle Stall Control for Switching Element Thermal Management

The control device implements periodic action by controlling the inverter circuit to operate in alternating phases: a first period where the electric motor generates driving torque to maintain the vehicle in stopped state, and a second period where torque generation is reduced or stopped to allow switching element cooling. This periodic alternation prevents continuous overheating while maintaining vehicle stability during stall conditions.

The control device applies preliminary action by proactively managing the torque generation cycles before critical overheating occurs. The system monitors and controls the duration of torque generation periods, and the cooling periods are initiated in advance to prevent thermal damage to the switching elements, rather than reacting after overheating has occurred.

Instead of continuous brake application, the control device uses periodic action by alternating between torque generation periods and cooling periods. During cooling periods, the electric motor torque is reduced or stopped rather than applying brakes, which allows cooling while minimizing the impact on startup readiness. This approach reduces the thermal management time compared to brake-based cooling.

The control device replaces the mechanical brake system with an electrical control approach. Rather than using the brake unit to cool the inverter circuit (mechanical method), the system uses electrical torque control to manage heating and cooling cycles. The electric motor itself is used to control thermal conditions by adjusting its torque output, eliminating the need for mechanical brake intervention and associated startup delays.

The control device implements periodic action by establishing a cycle of torque generation and cooling periods. Before each torque generation phase that would cause heating, a cooling period is inserted where torque is reduced or stopped. This periodic pattern allows the system to accumulate enough cooling to permit high-torque startup without immediate overheating, while still achieving smooth vehicle acceleration when torque is applied.

The control device applies preliminary action by preparing the thermal state before torque generation. Cooling periods are scheduled in advance to reduce switching element temperature to acceptable levels before the next torque generation phase. This proactive thermal management ensures that when high torque is needed for smooth startup, the switching elements are already cooled and can handle the increased thermal load without damage.