Supervisor demanding impossible workload at the very end of my PhD. Considering change of supervisor I am a PhD student in computer vision and I managed to publish 2 conference papers (one as first author and other as co-author) as a side project, since I had low quality data during my PhD.

Currently my supervisor is demanding a huge amount of work to be completed in 6 months - he is telling me to write 2 journal papers and a thesis!

My PhD always had problems with lack of data, but my supervisor never acknowledged that. After my papers had been rejected because of the low quality data, he acknowledged we needed to develop a better dataset.
So, I have been working for one year developing a novel high quality dataset for my PhD. But the problem is, I just have 6 months left and he is demanding at least 2 journal papers before the submission of my thesis.

I suggested to him to extend my PhD. He replied that I am allowed to take more time to complete my PhD, but he won't give funding to me after the original time passes. My supervisor actually has money for funding, since a post-doc left the project. But he said he will use this money to extend the contract of the other post-doc (the latter post-doc already has a 2 year contract).

It took 2 years to convince my supervisor that we needed a better dataset. I could be developing it from the first day of my PhD. Therefore, I consider it not my fault that I am in this situation where I am experiencing a major setback and now I am being rushed to complete my PhD.

To add to this, after I had developed the dataset, my supervisor is now giving it to new PhD students...

To give a bit of context, we had access to some prototypical sensor from the physics department, which I can use to collect lab data (the low quality data  that I had to work with in the beginning), but the sensor is really bad for the type of computer vision research that I am conducting. I always wanted a commercial sensor so I could collect more realistic data that would represent my PhD topic. I used the lab data for my research as I had no other choice at the time, but my paper was rejected because the reviewers claimed my dataset was not realistic, so they could not evaluate if my method would work for more realistic scenarios. After I developed the new dataset (after I managed to get my supervisor to buy a new sensor from my funds allocated for PhD travel), my supervisor is requesting to me to still work with the lab data and publish it before I move to the new realistic dataset.

Furthermore, my supervisor doesn't have knowledge about my research topic - all the meetings that I had with him were me explaining very basic concepts to him. I have been working completely alone, and I do not benefit from real academic discussions with him.

I suggested that I could work just with the lab data and write my thesis about it, and he could hire me as research assistant afterwards and I could publish more papers on the new dataset. But he wants me write 2 journal papers (one with the lab data and other with the new dataset) before the end of my PhD!

I never had a good relationship with my supervisor, he constantly criticises my work and never shows an alternative solution. And changing supervisor in my case is a bit more challenging since my PhD is industry funded and we have to sign a NDA.

I really think I don't have time to write both journals. I don't know what to do... I won't work without funding. I am really considering going until the end and asking for change of supervisor at any cost (but afraid of the consequences).
I agree with user Maarten Buis that this is probably too personal to really give good advice. But let me suggest a few things. 

You should probably optimize everything now for quick completion of your degree under a situation over which you have little control. 

While you can ask your supervisor for more funding, he has already said no. What has changed to make him say yes?

While you can complain to the institute that would most likely result in animosity from your advisor, not helping your path to completion. 

While you can ask for a different supervisor, that would set you back, possibly for years and not necessarily leaving you in a better situation, depending on the local culture generally. 

You have been given a steep hill to climb - two papers, etc. Start climbing. Do what you can. That is, in fact, all you can do anyway, but give it a good effort. Everything you do for that will get you closer to completion and will help build a good record of accomplishment for a future position. 

I would, myself, try to work on the two papers in tandem. Getting a rough outline of both as quickly as possible and then filling in the details as it becomes possible. I assume that the work behind the dissertation contributes to the papers and is done or nearly so. That might make it possible to work on all three items simultaneously. Then, as the deadlines approach you will have made progress and if you need additional time for completion you have an argument for it and additional funding. 

No, it isn't right or fair. But a short term push toward a better future might be better than just fighting it when you have not much chance of winning the fight.