Move a piezo

[avikde]

• fix cube file
• get micros working
• IMU
• set duty cycle as sin
• without piezo connected get scope output plot and data of the voltage at the output
• inductor jumper? make sure the signal is reasonable
• ADC reading of voltage
• closed loop voltage tracking
• 100Hz -> 370Hz
• try to eliminate any "noisy jitters"
• same at higher voltage: 50?
• connect piezo and see if the different capacitance means gains need to be changed

Sim:

• circuit sim

Info:

• https://www.thorlabs.com/thorproduct.cfm?partnumber=PB4NB2S capacitance 550nF. could use a 100nF capacitor in the meantime. Based on volume, mass should be ~1g.
• gate driver https://www.infineon.com/dgdl/Infineon-2EDL05x06xx-DS-v02_09-EN.pdf?fileId=db3a30433e30e4bf013e3c649ffd6c8b seems to be working ok

Open loop (sine)

Closed loop results

[avikde]

Low side tests with 1nF cap at load

10KHz PWM, 1Hz sine.

LO output is showing the correct PWM @ 15V with changing duty cycle.

However, Vs looks like this

Vs at 10KHz PWM, 100Hz sine

Vs at 100KHz PWM, 100Hz sine

Vs at 100KHz PWM, 10Hz sine

Vs at 100KHz PWM, 1Hz sine

Vs at 100KHz PWM, 0.1

Hz sine

[avikde]

with 100ms period

Cyan=LO, yellow=VS

makes sense: when the FET is on, the voltage snaps to zero even with the cap. Need the inductor to slow down the current?

with 1ms period

[avikde]

Questions:

• inductor needed or not: circuit analysis ODE, and then check with no (L=0) or different L values
• can only low side work for the low side cap? maybe not since the middle is just floating without the high side turning on

[avikde]

Lo = yellow, VS (before inductor) = cyan

Zoomed in

• as soon as lo gate turns on, voltage drops to 0, but then rises again! that must be coming from the cap

Same but now cyan is AFTER the inductor

• oscillations are due to LC dynamics. want slower time constant for that or faster for PWM?

[avikde]

Still falls too fast with this LC pair.

Looking much better with 0.1uF cap!

[avikde]

Open loop test result

open loop test 2: 1MHz base

Problem was sync (motivating feedback!) 10KHz base, 100Hz desired sine wave

Output @ 50v pp

[avikde]

ADC somewhat working.

• vmax ~300 with power off
• 1260 (vmax[1]) at ~19.5V (from scope)
• 1838 (vmax[1]) at ~30V (from scope)
• 2358 (vmax[1]) at ~40V (from scope)
• 2846 (vmax[1]) at ~50V (from scope)
• 3390 (vmax[1]) at ~60V (from scope)
• 3889 (vmax[1]) at ~70V (from scope)

https://docs.google.com/spreadsheets/d/1NQQbD_Zaig3STnTJG6g7wlEqw0pASV7lOaqTsuFVBwo/edit?usp=sharing

[avikde]

Closed loop

Vpp = 20, gain = 0.001

Vpp = 20, gain = 0.003

Gets noisier, a little more accurate, but since shape is still wrong.

Seems like the voltage rises much faster than it falls?? put a 0.5 for the rising inputs

Sinusoid with these params

Triangle

[avikde]

The piezo specs say 150V, 370Hz resonance. https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=10958&pn=PB4NB2S

[avikde]

zoomed in 300Hz

duty cycle being used is very small. can probably increase the number of steps?