Discussion Overview
The discussion revolves around the phase currents in trapezoidal switching, specifically focusing on calculations related to RMS values, assumptions regarding motor characteristics, and the effects of back EMF. Participants explore theoretical and practical aspects of motor performance under trapezoidal switching conditions.
Discussion Character
- Technical explanation
- Mathematical reasoning
- Debate/contested
Main Points Raised
- One participant calculates the RMS value of phase voltage as Vp = 0.4714Vs, leading to a current of 16.52 amps per phase, based on a supply voltage of 20V and a phase-phase resistance of 0.57 Ohms, and seeks validation of these calculations.
- Another participant requests clarification on the assumptions made in the calculations.
- A participant notes that currents are influenced by inductance and back EMF, questioning the implications when applied voltage equals back EMF, leading to zero current flow.
- One participant emphasizes the importance of including assumptions such as RdsOn of the source and complex load impedance when calculating RMS current, mentioning a simulation that yields a current of 16.46 Arms for a specific load.
- A question is posed regarding the expected efficiency ratio (Tau/T) for a practical motor at maximum RPM, along with a hypothetical inquiry about the rationale for using only 2/3 of the supply voltage.
Areas of Agreement / Disagreement
Participants express differing views on the assumptions necessary for accurate calculations and the implications of back EMF on current flow. The discussion remains unresolved regarding the optimal conditions and parameters for trapezoidal switching.
Contextual Notes
Limitations include potential missing assumptions related to motor characteristics, the dependence on specific definitions of terms like back EMF, and unresolved mathematical steps in the calculations presented.
Who May Find This Useful
Individuals interested in motor control, electrical engineering, and those studying the effects of switching techniques on phase currents may find this discussion relevant.
