Martin A said:
What is it that makes FOC controllers cost twice the price, the componentry or something else?
That's a good question.
Comparing a cheap cloned commodity knock-off of a BLDC trap controller to any first line product is fraught with problems.
And re John's comment about Russian electronics - we have that, see Adaptto. But should the market be depending on starving companies to define the value of a product?
Both controller types have (generally three) phase FET H bridges driving the motor windings. Trap controllers have a very simple CPU or chip that is reading the three binary hall inputs and driving PWM into the FET bridge, while monitoring battery current via a shunt. Literally a one dollar chip can do the brains of a trap controller.
Let's make a list of some of the things that an FOC controller has that a Trap controller doesn't.
FOC controllers have motor current sensors, at least two of them. They must have high bandwidth to be used for FOC control. They feed ADCs that need to be fast and fairly precise and synchronized to produce the data the algorithm needs for good control. These are more expensive than the shunt a trap controller uses.
FOC controllers have better drivers for their FET arrays. They are managing currents into and out of all three phase wires simultaneously, they must actively control all the FETs synchronously and not rely on the diodes to conduct motor current, so they need better control precision.
FOC controllers need to manage noise much better since they are making critical measurements while they are controlling. This requires better design and more components.
FOC controllers have significantly more computing power and complicated control algorithms to implement in real time.
Many licenses and patents exist for FOC controls, this may have impact on the cost of the software.
The FOC controller needs to know more about the motor and operational characteristics, so documentation, tuning software and support costs all go up.
The software needs to be more suited to the application, so an FOC program for running a lathe won't be suitable for an ebike. So the controller must be more customizable than a Trap controller. Again documentation and support costs go up.
I'm sure there are many more details that I haven't covered here. Basically an FOC controller is implementing a modern optimized mathematical control algorithm whereas a trap controller is basically implementing a 200 year old mechanical commutator (invented in the early 1800's) using electronics.