ADI brings improved efficiency to motor control applications

"We are looking for our customers, who are the architects of drives, to change their architectures and potentially to change their overall platforms," Anders Frederiksen, ADI's marketing manager for motor and power control, told New Electronics. Frederiksen was referring to the increased need for efficiency in both motor control and PV inverters – applications served by the company's new CM40x family of mixed signal control processors. The devices have an ARM CortexM4 at their core running at 240Mhz, and also feature a 16bit a/d converter with 14bit accuracy. Frederickson commented: "So what we are doing is mixing what is probably the highest performance M4 floating point device in the world with most advanced analogue front end built in a multi-die approach. We have found from our customers that this will bring them to that level of efficiency – it will give them the performance they need for more accurate control. We are not launching a product – we are launching a way to design your system. It is as platform approach going forward." An assp with a Cortex-M4 with floating point extension, it has 348kB of parity enabled so it is secure zero wait state SRAM, security runs through to the 2MB flash memory and there is a cache to speed up the performance of that. "So the idea here is that you run the real time application at full 240Mhz zero wait state and where needed you hand-pick your algorithms or use the flash just for storage, programme or whatever it is that is needed for your application," said Frederickson. There is a standard development board for motor control but there is also a high voltage power board so that developers can get as close as possible to a real life drive. Equally there are two versions of the development board for use as a PV inverter. "It is very accurate in its measurement of currents, voltage and it has the full featured functionality of the end application," Frederickson added. The development board features the AD7401A which is the isolated sigma delta unit from the ADI portfolio. "It gives 14bit accurate current measurement," explained Frederickson, "and normally what you would do is feed it through an fpga to demodulate the bit stream coming out of that – typically 10 to 20Mhz and that is beyond most microcontrollers – but the sinc filter we have built into this family has that capability. What this means is that we have taken the fpga costs off the system while still offering the same functionality." Frederickson would not state specific efficiency improvement figures on account of different load conditions, but believed: "compared to drives we can gain typically about 5 and 10%."