Robust Control of Winding-Based DC-Bus Capacitor Discharge for PMSM Drives in Electric Vehicles

Active discharge circuit is of great significance for discharging the dc-bus capacitor voltage to safe voltage in the electric vehicles (EVs) based PMSM drive system when EVs encounter an emergency such as a crash event. However, when electric vehicle occurs a collision, the active discharge circuit may be damaged or failed, which poses a great electric threat to the passengers and succors. In order to resolve the problem, this article proposes a winding-based dc-bus capacitor discharge method. To quickly discharge the dc-bus capacitor energy, the machine windings are used as discharge resistance with active discharge circuit fault. For the purpose of reducing the bus voltage to safe voltage as soon as possible, the discharge method can be divided into two phases, rapid discharge stage and bus voltage regulation stage. Firstly, the dc-bus voltage will be dropped to safe voltage due to the large flux-weakening current applied to the d-axis. Secondly, in order to stabilize the bus voltage at safe voltage, an extended observer state (ESO) is designed to estimate and compensate the total power loss that is regarded as disturbance in bus voltage regulation stage. The parameters of the proposed ESO are designed and the tracking performance is analyzed. Finally, the proposed discharge technique is validated by both simulation and experiments, which are conducted on a three-phase SPMSM drive platform.