mxlemming
100 kW
- Joined
- Jul 17, 2020
- Messages
- 1,122
I've been looking for a while now for DTC examples. It seems to be very much proprietary and locked up in ABB and a few others inverters.
I see little objective evidence that it's any better than FOC, and also very little in terms of how it actually works... All the academic papers seem to be based on using some black box attained and comparing the torque ripple etc.
Is anyone aware of an actual open source implementation, an actual explanation of how it works etc?
Masses of nonsense with people implying it's sensorless intrinsically (it's not... You need an encoder/observer) and having faster torque response (really is this meaningful over FOC running with 30khz+ switching?)
From what i can tell it's basically:
Know position and speed from encoder or otherwise,
Know current from very good phase shunts/hall sensors/whatever
Look up predetermined values for how long to turn on each switch to get required current, which can be calculated based on inductance, resistance and BEMF
Write pwm values, or write timed on output
Wait until on period/other arbitrary time has elapsed before rerunning the control loop
Since you know current and inverter voltage you can construct an observer.
Is this correct? Does anyone have any greater insight?
It seems to me that with proper FOC the limiting factor usually being the ability to resolve position, this doesn't obviously present any great advantage.
I see little objective evidence that it's any better than FOC, and also very little in terms of how it actually works... All the academic papers seem to be based on using some black box attained and comparing the torque ripple etc.
Is anyone aware of an actual open source implementation, an actual explanation of how it works etc?
Masses of nonsense with people implying it's sensorless intrinsically (it's not... You need an encoder/observer) and having faster torque response (really is this meaningful over FOC running with 30khz+ switching?)
From what i can tell it's basically:
Know position and speed from encoder or otherwise,
Know current from very good phase shunts/hall sensors/whatever
Look up predetermined values for how long to turn on each switch to get required current, which can be calculated based on inductance, resistance and BEMF
Write pwm values, or write timed on output
Wait until on period/other arbitrary time has elapsed before rerunning the control loop
Since you know current and inverter voltage you can construct an observer.
Is this correct? Does anyone have any greater insight?
It seems to me that with proper FOC the limiting factor usually being the ability to resolve position, this doesn't obviously present any great advantage.