There are few greater joys as an engineer than taking something new apart to see how it works. Last week Vladimir Brunstein and I got started on the design project by dissecting a commercial induction stove and doing some initial measurements to see how it works. We have significant progress, and Vladimir has some addition testing using an oscilloscope to validate our assumptions.
There are five major “components” to an induction cooktop:
- The power supply (on the main circuit board) – includes heat sink and exhaust fan
- The control circuit (on the main circuit board) along with some sensors
- The induction coil (on top of the main board, under the glass cooking surface
- The user interface (display and buttons)
- The enclosure (bottom case and glass cooking surface)
The main surprise was how compact and “simple” the control board was. The board uses “through hole” components (rather than surface mount) and most of the control appears to be handled by a custom microcontroller on the lower section right of the board. The display appears to have its own controller chip. Since consumer induction cookers all tend to work the same way (and do it very well), we don’t want to mess with the controls at this stage — our focus will be on how to replace the power supply that currently runs off AC with one that will run off DC (battery).
But why bother, if everything is as optimized as this board tends to suggest? In a COTS (commercial-off-the-shelf) solar electric cooking system, the battery must run power through an inverter, which converts it to AC for input to the induction cooktop. If we can eliminate the inverter, it will reduce system cost, increase the efficiency and also improve the reliability.
More updates will be posted as we start actually building and testing the new power supply.