The overmodulation operation of a three-phase inverter can enhance the output torque capacity of the AC motors. In this case, the enhancement varies depending on the overmodulation schemes applied for the overmodulation operation. Steady-state overmodulation schemes are usually employed to give the unit voltage gain up to the six-step mode of an inverter. However, these schemes lead to a slow transient response of the output torque and require a complex algorithm for implementation. On the other hand, dynamic overmodulation schemes can achieve a rapid transient response of the output torque and are simple to implement. However, inverters using these schemes cannot work up to the six-step mode since the voltage gain of the inverter is less than one in the overmodulation region. In this paper, a technique is proposed that can increase the DC voltage utilization of an inverter by improving the voltage gain in dynamic overmodulation operation. An inverter with dynamic overmodulation using the proposed technique can work up to a six-step mode. Hence, AC motors can obtain enhanced torque capacity during flux-weakening operation. Consequently, an improved transient torque response can be achieved in the high-speed region. From simulation and experimental results, it was validated that the proposed technique can be used for dynamic overmodulation operation for not only the continuous PWM but also the DPWMs (discontinuous pulse width modulations).

三相逆变器的过调制操作可以增强交流电动机的输出转矩容量。在这种情况下，增强取决于用于过调制操作的过调制方案而变化。通常采用稳态过调制方案，以使单位电压增益达到逆变器的六步模式。但是，这些方案导致输出转矩的缓慢瞬态响应，并且需要复杂的算法来实施。另一方面，动态过调制方案可以实现输出转矩的快速瞬态响应，并且易于实现。但是，使用这些方案的逆变器无法在六步模式下工作，因为逆变器的电压增益在过调制区域中小于一。在本文中，提出了一种通过改善动态过调制操作中的电压增益来提高逆变器的直流电压利用率的技术。使用提出的技术进行动态过调制的逆变器可以工作到六步模式。因此，交流电动机可以在弱磁通过程中获得更高的转矩容量。因此，可以在高速区域中实现改善的瞬态转矩响应。从仿真和实验结果可以证明，所提出的技术不仅可用于连续PWM，而且还可用于DPWM（不连续脉冲宽度调制）的动态过调制操作。因此，交流电动机可以在弱磁通过程中获得更高的转矩容量。因此，可以在高速区域中实现改善的瞬态转矩响应。从仿真和实验结果可以证明，所提出的技术不仅可用于连续PWM，而且还可用于DPWM（不连续脉冲宽度调制）的动态过调制操作。因此，交流电动机可以在弱磁通过程中获得更高的转矩容量。因此，可以在高速区域中实现改善的瞬态转矩响应。从仿真和实验结果可以证明，所提出的技术不仅可用于连续PWM，而且还可用于DPWM（不连续脉冲宽度调制）的动态过调制操作。