ZERO VECTOR FREQUENCY TUNING
What’s ZVF?
Zero Vector Frequency is the frequency the FOC motor control loop runs at, usually between 20-40kHz
Why tune it?
For various reasons the ZVF frequency can cause interference with the IMU causing an unstable feeling board.
Most commonly ZVF interference issues are noticeable when accelerating hard, at certain speeds (often 10-20mph) the nose will start going up and down unpredictably, often quite subtle but noticeable enough to be unsettling.
Other interference effects can be motor noise, especially when LEDs and noisy buck converters are involved. For example on the Thor300 and on the ADV1 interference with the LEDs is quite noticeable and adjusting your ZVF can help.
How to tune it?
Typically you want to stay between 25-35kHz
Start by going up and down in 0.5kHz increments to eliminate light interference noise at low speed.
From there tune in 0.1kHz increments to eliminate nose hunting issues when accelerating or braking hard.
Easy fix for LSM6 IMU ESCs
If the above doesn’t solve your problem, there’s one last resort change you can make that almost always works:
- Manually change the IMU frequency from 832Hz to 416Hz
- DOES NOT WORK for BMI160 IMUs (800Hz is standard freq)
** so don’t do this with ADV1 and V-Kits, or with Spintend UBox ESCs
Note that this trick usually doesn’t help with low-speed interference noise when the lights are on. But it almost always solves the nose hunting issue!