ARM-based Freescale Kinetis MCUs focus on motor control and digital power conversion
Modern sensored and sensorless motor control, Freescale says, is demanding on the MCU and requires precise speed and position measurement in parallel with general application task processing. The MCU must be able to support a range of control algorithms – from entry level BLDC to advanced PMSM and ACIM control loops – as well as offer high speed/resolution ADCs and PWMs for fast, accurate signal capture and response.
The Kinetis V series’ fast signal acquisition and processing capabilities, combined with the Kinetis Motor Suite, provide a unified hardware and software platform for developing scalable, cost-effective motor control systems. Designers can achieve increased efficiency, quieter operation, and improved reliability.
The KV4x family is the flagship of the existing V series, targeting digital power conversion designs, as well as PMSM and ACIM applications requiring high dynamic control. KV4x MCUs incorporate a 150 MHz ARM Cortex-M4 processor with floating-point unit executing from up to 256 kB of Flash memory via a 128-bit wide interface that minimises CPU wait states. With up to 30 timer channels – twelve provided by the highly flexible eFlexPWM – KV4x family devices provide multiple three-phase motor drive capabilities supporting dead time insertion, complementary pairing of PWMs, half cycle reload and fault detection. For sensorless motor control speed/position detection, two 12-bit ADCs support sample rates of up to 1.9 Msamples/sec and can be triggered by any module connected to the MCU’s internal peripheral crossbar, including timers, analogue comparators or GPIO. For switched mode power supply applications, an eFlexPWM module provides 300 picosecond resolution, while the ADCs sample at 4.1 Msamples/sec. This improves real-time control, ensuring that critical timing windows for data gathering and system updates are met. The KV4x family’s high degree of feature integration enables up to 30 PWM outputs, 38 ADC channel inputs, as well as CAN, UART and SPI interfaces to be housed in a 100-pin LQFP package.
The KV3x family, also Cortex-M4 based, targets intermediate PMSM applications with CPU frequencies of 100-120 MHz, up to 512/96 kB of Flash/SRAM and an optional external bus interface for off-chip system expansion.
The KV1x family represents the entry-level of the series and integrates the fastest-available Cortex-M0+ MCU core. With a CPU frequency of 75 MHz, plus hardware divide and square root block, KV1x devices offer a performance increase of more than 25% in math-intensive applications compared to other MCUs in the family’s class. Packing this high processing efficiency into a small, 32 kB solution positions KV1x MCUs as cost-effective options for BLDC and PMSM designs that currently rely on larger, more expensive 32-bit MCUs, the company claims
Traditionally, PID loop tuning is trial and error based, requires in-depth motor control expertise and results in non-optimal system performance that can degrade over time. Kinetis Motor Suite addresses these issues, simplifying the development cycle, delivering more predictable system response and reducing time to market.
The Kinetis Motor Suite consists of three software components for tuning, observing and managing motor control system operation: the Kinetis Motor Tuner, a GUI for motor parameter configuration that enables fast, precise PID loop tuning in minutes; Kinetis Motor Observer, advanced software pre-programmed into the MCU that enables tuning of control loops and estimation blocks to regulate motor and inverter efficiency, power factor, current/torque ripple and noise, and; the Kinetis Motor Manager, which provides a real-time, non-intrusive display of system variables and the MCU memory map. The motor manager includes a software oscilloscope with debugging and data logging capability. Kinetis V series MCUs pre-programmed with Kinetis Motor Suite software will be available to order in the third quarter of 2014.
Production-qualified Kinetis KV1x MCUs are now available with pricing from $0.99 (10,000). Kinetis KV3x MCUs are currently sampling, and Kinetis KV4x MCUs are planned to sample in Q3 2014.
Freescale; www.freescale.com/Kinetis/vseries
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