Variable driving conditions can cause an integrated starter generator hybrid powertrain to switch between multiple drive modes. The addition of a permanent magnet synchronous motor (PMSM) gives hybrid powertrains complex electromechanical coupling characteristics. The effects of excitation sources, such as the engine and PMSM, may cause unstable behavior in the drive system, such as speed fluctuations during mode switches due to electromechanical coupling characteristics. Although traditional mode switch strategies and methods have achieved measurable results, they are difficult to improve. To solve this problem, we first considered the combination and separation of the clutch and establish a nonlinear model of mode switches for series–parallel hybrid electric vehicles. Then, we predicted the instability boundary of the drive system during mode switches. Experimental results indicated that the proposed instability boundary has higher accuracy. Numerical results showed that the three-mode switches have different thresholds of instability for the clutch structure gap. The decrease in electromagnetic torque and the increase in load excitation amplitude will improve the critical value of the clutch structure gap. The increase in load excitation frequency causes the critical value of the clutch structure gap to drop first and then rise.

可变的驾驶条件会导致集成的起动发电机混合动力系统在多种驱动模式之间切换。添加永磁同步电机 (PMSM) 使混合动力系统具有复杂的机电耦合特性。发动机和 PMSM 等激励源的影响可能会导致驱动系统中的不稳定行为，例如由于机电耦合特性导致模式切换期间的速度波动。传统的模式切换策略和方法虽然取得了可观的效果，但难以改进。为了解决这个问题，我们首先考虑了离合器的组合和分离，建立了串并联混合动力汽车模式切换的非线性模型。然后，我们预测了模式切换期间驱动系统的不稳定边界。实验结果表明，所提出的不稳定边界具有更高的精度。数值结果表明，对于离合器结构间隙，三模式开关具有不同的不稳定阈值。电磁转矩的减小和负载激励幅值的增加会提高离合器结构间隙的临界值。负载激励频率的增加导致离合器结构间隙的临界值先下降后上升。电磁转矩的减小和负载激励幅值的增加会提高离合器结构间隙的临界值。负载激励频率的增加导致离合器结构间隙的临界值先下降后上升。电磁转矩的减小和负载激励幅值的增加会提高离合器结构间隙的临界值。负载激励频率的增加导致离合器结构间隙的临界值先下降后上升。