Discussion Overview
The discussion revolves around determining the torque constant (Kt) and back EMF constant (Ke) of a brushless DC (BLDC) motor, specifically in the context of an in-wheel motor used in electric scooters. Participants seek methods for measuring torque at a given current and understanding the relationship between Kt and Ke.
Discussion Character
- Technical explanation
- Experimental/applied
- Debate/contested
Main Points Raised
- One participant inquires about the torque constant and back EMF constant, seeking assistance in measurement techniques.
- Another participant suggests that the easiest way to find Kt and Ke is to refer to the motor specifications provided by the manufacturer.
- It is proposed that Kt can be calculated by measuring the generated torque and the current required to produce it, with a formula Kt=Torque/Ampere.
- Methods for measuring torque are discussed, including using a spring scale, a torque wrench, or a prony brake.
- There is a question about whether Kt equals Ke in BLDC motors, with one participant stating that ideally they should be equal, but in practice, they may not be.
- Units for Kt and Ke are clarified, with Kt expressed in Nm/A and Ke in RPM/V, noting that Ke may also be expressed as Volts/RPM.
- Participants discuss measuring resistance (R) and inductance (La) using an ohmmeter and an LCR meter.
Areas of Agreement / Disagreement
Participants express differing views on the relationship between Kt and Ke, with some suggesting they are ideally equal while others indicate practical discrepancies. The discussion remains unresolved regarding the exact nature of this relationship.
Contextual Notes
Participants have not reached a consensus on the equivalence of Kt and Ke, and there are varying methods proposed for measuring torque and other parameters, indicating a range of assumptions and conditions that may affect the results.