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Thanks , Uncle Duncan , for the video. Question : could swapping the < A > lines at the HX711 have solved the sign issue? I cannot wait for the next video.

I am currently do some experiments on LED driver running OB5628 ic... nice to see these type of videos 😍

Another great video! I'm starting to see VFDs applied in refrigeration systems at my work. Specifically the ultra low temp freezers (-86C) that we use for cyrogenic storage. Instead of driving the high and low side compressors directly with mains single phase, they are now using 3 phase VFDs with an inverter. To make them more efficient as you said once they reach steady-state. But I appreciate your in depth analysis!

I always love a good buck converter video! Nice explanation. I tend to see the drivers fail instead of the LEDs. And its always funny that you can never find the datasheet for these mystery chips on the cheap stuff. Good stuff!

That’s a great project, really interesting to get anything down to the milligram and the setup of how you got there from the loadcell to the 3D printed parts Continued Success Fabrizio

Thank you Uncle D.

Which communication cable you used to connect with the drive

Can you set the color manually or do they always cycle through the colors?

i like it from pakistan

i like it from pakistan

I need something like this because I have to fill up a hole with JBWeld so I can drill and retap the hole. Unfortunate part is it's a two part epoxy so its hard to mix it and then shove it in something to inject in the hole. I dont think I can scoop it and put in the hole after mixing it. Cant really mix it in the hole. I dont have a syringe like this. I believe I used to but not anymore

😂👍👍👍

Hello Duncan Happy New Year all the best

### Field Weakening in Induction Motors with Variable Speed Drives (VSDs) Field weakening is a technique used to increase the speed range of an induction motor beyond its nominal speed (base speed) while maintaining efficient operation. This is accomplished by reducing the stator flux, which effectively lowers the back electromotive force (EMF) and allows the motor to operate at higher speeds. Below is a detailed explanation of how this process works: --- #### **1. Background on Induction Motor Operation** - **Base Speed Operation**: At speeds below the base speed, the motor operates in the "constant torque region." The VSD provides a constant voltage-to-frequency (V/f) ratio to maintain the required magnetic flux in the motor for torque production. - **Field Weakening Region**: When the motor needs to operate above the base speed, the voltage limit of the drive is reached (typically the supply voltage). To allow further speed increase, the stator flux is deliberately reduced, entering the "constant power region." --- #### **2. Mechanism of Field Weakening** - **Magnetic Flux Reduction**: The flux in an induction motor is proportional to the stator voltage and inversely proportional to the frequency. As the frequency increases beyond the base frequency, the voltage cannot increase further due to the drive's limitations. To maintain operation, the VSD reduces the stator flux. \[ \phi_s = \frac{V_s}{k \cdot f_s} \] where: - \(\phi_s\): Stator flux - \(V_s\): Stator voltage - \(f_s\): Supply frequency - \(k\): Motor constant - **Current Control**: The VSD adjusts the current vector dynamically to control the flux and torque-producing components. The flux component is reduced, while the torque-producing current is prioritized to maintain motor performance. --- #### **3. Impact on Motor Performance** - **Torque Reduction**: In the field-weakening region, the torque output decreases because torque is proportional to the flux and the torque-producing current. With lower flux, the maximum torque capability is diminished. \[ T = k \cdot \phi_s \cdot I_q \] where: - \(T\): Torque - \(\phi_s\): Stator flux - \(I_q\): Torque-producing component of the current - \(k\): Motor constant - **Constant Power Operation**: Despite the reduced torque, the motor can maintain constant power because power is the product of torque and speed: \[ P = T \cdot \omega \] As speed (\(\omega\)) increases, the reduction in torque is offset by the increase in speed. - **Efficiency Considerations**: Efficiency may decrease in the field-weakening region due to increased copper losses and reduced magnetic efficiency. --- #### **4. Role of the Variable Speed Drive** - **Dynamic Control**: The VSD monitors motor speed, voltage, and current to calculate the required flux and adjust the frequency and current accordingly. - **Protection Mechanisms**: The VSD ensures safe operation by preventing the motor from entering unstable regions (e.g., excessive speed or overheating due to high currents). - **Field Weakening Curve**: The drive uses predefined or user-configured settings to manage the transition from the constant torque to the constant power region. --- #### **5. Applications of Field Weakening** Field weakening is particularly useful in applications requiring high-speed operation beyond the base speed, such as: - Centrifugal pumps and fans - Machine tools - Electric vehicles - Industrial conveyor systems --- ### **Key Considerations** - **Motor Design**: Not all induction motors are suitable for field weakening. Motors must be designed to handle the thermal and mechanical stresses associated with high-speed operation. - **Drive Programming**: Proper configuration of the VSD is essential to optimize field weakening without compromising motor life or performance. - **Operating Limits**: Continuous operation in the field-weakening region may result in overheating or reduced motor lifespan if not managed correctly. By leveraging the advanced control capabilities of modern VSDs, field weakening enables a significant extension of the operational speed range of induction motors, making them versatile for various industrial applications.

Yup, this is super useful. I'm sharing it left right and center. 👍👍👍

Thanks for doing that for us . As usual , a picture is worth a thousand words . It makes a complex situation easier to understand

Genius!

This is an awesome tip, thanks Uncle D... Would you mind if I share it on other groups?

Mamod are no longer in business..

Thank you for showing the oscilloscope traces . It really to make the subject come to life. Coming down with the supply voltage means a safe and instructive talk Oscilloscopes ? ..............Every home should have one !

Interesting 😂

Excellent . I like the way the holes in the ceiling diffuser create the impression of overhead luminaires . Clever stuff

I remember those cards. 😅

That's no corvette

Now THIS is cool! And creative!!

I was wondering how you did it. 🤗

😊 Almost as 'romantic' as the steam engine. 😅😅🤗👍👍👍

Really cool project and looks amazing! The setPixelColor tree is hurting my eyes tho 🫣

I have one of those AIO pump and it came already making a clacking noise, i guess it is about the rotor hitting the stator case. Thickening the water with oil helped a bit but I'm still searching to solving it definitely

Yet another example showing how invaluable an oscilloscope is for generating understanding. Thanks for that

The scope signal is inverted, only thought about that afterwards. So the flat line areas is where the led is on permanently and the pwm is where it gets dimmed.

Awesome video! I didn't know you had a channel. I just subscribed. Really enjoy all the detail you get into. I have to go back and go through your catalog of videos!

Thanks for sharing . Could you at, some stage, repeat the experiment for a capacitor ?

Really found that interesting .Charles Kettering in the USA produced the first successful automotive self starter more than 100 years ago . He was the first to realise that the motor did not need to be continuously rated for the power it delivered . The motor is a series motor with brushes .exactly as you just showed us

That Variac you have is fantastic, a dive into the ins and outs of the Variac like what’s being is it a toroidal transformer just something things to put in a future video if you see fit to film one Continued Success Fabrizio

This is living proof that an ounce of short practical experiment is better than a ton of theoretical waffle Not only did you show the poor result , but by measurement you showed us why .Thanks for that

Great video Duncan, but are you diving into Johnny Depp, if possible change title to deep, otherwise everything fantastic especially your oscilloscope, is that an oscilloscope and a tester as well, great setup you have Duncan, and interesting explanations about inducters other circuit explanations thank you Continued Success Fabrizio

Very interesting , I've learnt a lot . Thanks for going to the trouble to show us this . Always nice when theory and practice come together .

When it comes to reactive components , inductances don't like having their current changed and react by changing their terminal voltage in an effort to keep the current constant . Capacitors don't like their voltage to be changed and react by drawing current in an effort to keep their terminal voltage constant . Thanks for showing this so clearly .

Hello, this happens to be the first video of yours that I've watched. Interesting and clear explanation of the some of the implications of power factors. Noting that you have also done hundreds of podcasts and videos, I'd like to say thank you for putting in such long-running effort for the benefit of others. (And I'm also surprised I've not come across your work before.) If you don't mind, I offer one constructive criticism. Although you have accomplished the intention of such a demonstration, please consider what is missing if someone wants to replicate your experiment. This is an issue I've noticed among many DIY or educational presentations. Certainly, it would be a bit silly to list "blender" as one of the items needed. But what about the transformer? And certainly the DIN-rail mountable VSD needs at least a part number shown (turn the unit on its side?). Just from a cursory glance from the list of your other videos, it's clear you've used the VSD at least several times before and perhaps have identified it previously. However, consider my first encounter as an instance of a viewer just jumping into the middle, thus skipping the requisite prior context. It would be a simple matter of copy and paste to replicate the parts list from previous videos. It's hard to explain why that is a real time saver for people like me. I want to dig right in, not go hunting through other videos looking for the gadget in question. Ideally, include links to where to buy the items in the description section. I also *prefer* to purchase things that are set up as so-called "affiliate links" to support in a small way a presenter's efforts. Back to the VSD a moment. Granted, that device is a sophisticated model having an ethernet connector and what appears to be a 12 pin interface port as well. It certainly isn't a cheap piece of kit. That said, you never know who might be inspired by one of your presentations, becoming enthused to follow up even if it takes some time to save up and purchase such a device. Looking forward to watching more of your work. Cheers, H in Florida, USA (waiting for a monster hurricane to blow by ...)

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I wonder if there is a difference in pressure when you do this. I wan to make an aquarium pump connected to an ESP32 and plug it into a pneumatic toilet flush controller. That way I can use IR wave sensors to flush the toilet.

What brand is the VFD ?

I remember years ago that a customer used normally closed contacts on the motor start contactor to connect large value AC capacitors to the motor terminals when the contactor dropped out . The motor was required to stop as quickly as possible and the system did not utilise a VSD . I realise now that the capacitors could not absorb power , but the circulating current heated the rotor bars to absorb the system inertia

Interesting 🙏

Thanks for that . Do you know what the Coefficient Of Performance (COP) for these small systems is ? Does it pump more heat than the power consumed by the compressor ?

Effaçeur ¢ompul$if déte¢té.

gotta look into reflected impedances. your "workpiece" is a single turn secondary. the coil a primary of "x turns". secondary resistane reflects at the square of turns ratio. using that you can figure out the impedance of the work, and design the coil to operate at determined power levels... stay within component ratings... need a pretty high frequency for thin material, skin effect nonsense... and, dont run long thin wires. you want the feeder to be as capacitive as possible, ie, thin plates/ribbon with insulator clamped between. try to keep the inductor and magnetic fields constrained where it matters... around the workpiece. would get much better results with that adhesive copper "slug barrier" tape, rather than a pancake.

with that small coil you can heat that screwdriver to red-hot.

My mug is ceramic, so my thought would be to make an induction heater pad and put a piece of steel over it with a weight sensor to put a bit more energy as the weight increases. I could tare it with an empty mug, so presumably it would turn off without any coffee and the less coffee there is, the less heat.