White Paper: Motor Control Designs with an Integrated FPGA Design Flow

 This white paper describes a recommended design flow that leverages Altera® FPGAs’ adaptability, variable-precision digital signal processing (DSP), and integrated system-level design tools for motor control designs. Motor-driven equipment designers can take advantage of the performance, integration, and efficiency benefits of this design flow.

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Motor Inverter Solution

Today, microcontroller  units (MCUs) control most power electronics, mainly because MCUs are low cost and provide a high level of integration. MCUs are typically programmed in C or Assembly language and are well-suited to algorithms that are executed sequentially at a rate within the MCU’s capability. Designers of traditional MCU-based systems are facing new challenges, however, as their applications demand faster sampling rates and more complex algorithms. 

FPGAs are gaining acceptance in high-performance power electronics control systems due to their speed, flexibility, and integrated design tools. These devices are well suited for electric vehicles (EV) drive system applications such as Valuable Voltage DC/DC converters (VVC) and motor control due to their parallel architecture and ability to handle multiple complex algorithms simultaneously in hardware.

FPGAs offer:

  • Increased processing speed: Algorithms can be accelerated and parallelized in an FPGA’s programmable hardware
  • Flexible design of interfaces: For example, parallel analog-to-digital converter (ADC) interfaces and pulse-width modulation (PWM) outputs can be added to support new inverter topologies
  • Ease of programming: Main control loop code can be maintained in C and run on hard or soft processors. Code for hardware acceleration can be fixed or floating point and written in C or MATLAB/Simulink
  • Ease of integration: Interfaces for encoders or resolvers, sigma-delta ADCs, and external communications can be built into the FPGA fabric
  • Cost effectiveness: Part count can be reduced, development streamlined, and the platform can be updated without affecting the PCB

IPM Motor Control with FPGA by Model-Based Design

Altera has developed a reference design of an Interior Permanent Magnet (IPM) motor control with Direct Torque and Flux Control using a Space Vector Modulation (DTFC-SVM) algorithm in a Model-Based Design (MBD). The simulation result shows notable torque ripple reduction compared to a Field-Oriented Control (FOC) algorithm. It also shows a significant advantage over MCU-based, DTFC-SVM control due to the FPGA’s high- bandwidth control loop implemented in hardware using parallel processing techniques.

Torque ripple comparison:

DTFC-SVM DSP Builder Reference Design

Altera’s DSP Builder tool provides MathWorks’ Simulink design blocks and the ability to auto-generate HDL code. It also simplifies the design process by allowing engineers to directly implement into the FPGA the same model they used to simulate the system. In addition, it permits the designer to leverage a rich library of power electronics components when constructing the testbench or system simulation model.

DSP Builder Design Flow

For more detailed information, download the FPGA-Based Control for Electric Vehicle and Hybrid Electric Vehicle Power Electronics white paper.