Choose the most suitable motor control scheme
mcu, DSP or FPGA
different applications have different requirements for motor controllers. At present, there are various controller/driver solutions in the market, including standard controller/driver for specific simple applications, MCU, DSP and FPGA with external buffer grid slider quality: 200g (specification) driver and power level
mcu is the mainstream motor control scheme in the current market, which is suitable for high, medium and low-end motor control. Through the internal integrated motor control module, the development of motor control by customers can be simplified; Compared with the strong control function of DSP, it can better realize the servo control and protection function of the motor. In addition, in 32-bit processor, complex control of space vector, magnetic field positioning and PD closed-loop regulation can also be well realized by improving the operation speed
for simple low-power motor control applications such as small BLDC cooling fans, special standard motor control ICs can achieve low cost. But for demanding applications, it is more suitable to use DSP, MCU and FPGA, because other system management functions can be added, such as monitoring motor parameters and status, as well as communication with the host system. "However, DSP, MCU and FPGA require external gate drivers and power devices." Said khagendrathapa, global strategic marketing manager of diodes
"at present, 8-bit MCU is mainly used in low-cost and low-performance occasions, while 16 bit and 32-bit DSP/MCU are used in medium/high-performance occasions. Among them, DSC is relatively cost-effective." Charliewu, senior system engineer of Freescale microcontroller division, pointed out that "FPGA is mainly used to cooperate with DSC/MCU to generate special PWM signals. It is mainly used in high-power applications."
"As for the motor control scheme, DSP, MCU and FPGA have their own advantages. DSP is suitable for the control of high-end and complex motor systems because of its strong data processing ability and fast operation speed, such as the realization of space vector control algorithm of AC induction motor, sensorless spatial positioning, etc., but it depends on the maturity and stability of software algorithm, and has high requirements for developers. In addition, because the core voltage and interface level are mainly 3.3V or 1 . 8V, the drive circuit support of relevant level is required for motor driver. " Peng Tao, product manager of Fujitsu Microelectronics (Shanghai) Co., Ltd., pointed out that "FPGA can be well applied to customized motor drive through integrated logic circuit and special motor drive circuit, but it is slightly insufficient in the universality of motor control."
"the function of single chip microcomputer with DSP is generally used in high-end applications with faster speed requirements. Infineon's 16 bit single chip microcomputer and 32-bit single chip microcomputer are single chip microcomputer with DSP function, of which 32-bit supports floating-point operation." Mr. Shi Jingyan, senior director of sales and business development of Infineon Technology (China) Co., Ltd. industrial and diversified electronic market division, pointed out that "FPGA has its own characteristics. It is very flexible, but it has high entry threshold and high unit price. It is generally used in fields with small volume."
what is the view of FPGA manufacturers? This article invited two FPGA manufacturers to talk about the application status of their products in motor control
Xilinx Asia Pacific
current motor control requires high performance and efficiency, which puts forward higher requirements for control accuracy and response time. The technology based on vector control of asynchronous motor has been widely used since it was invented in the 1970s. This control method is now relatively mature, has been commercialized and the product quality is stable. However, because this method uses more complex coordinate transformation, it requires higher performance of the controller, such as operation speed and processing capacity. In addition, for some places where the cost and surrounding environment are considered, the speed sensorless technology of an experimental machine, which is also relatively common, has also been widely valued. This undoubtedly puts forward higher requirements for the processing capacity of the chip. With the rapid development of modern control theory, semiconductor devices such as MCU/DSP/FPGA and power electronic switching devices, the realization of high-performance speed sensorless vector speed regulation system is the development trend of motor control market in the future
mcu usually focuses on the number of I/O interfaces and the size of programmable memory. It is very suitable for occasions with a large number of I/O operations, so it is widely used in systems with low cost, low power consumption and low accuracy requirements. However, due to its limited processing capacity, the internal layout of the application field is relatively loose, which is greatly limited. DSP chip integrates analog/digital conversion, digital input/output, serial communication, motor control PWM signal output and other interfaces, so it makes the hardware design of motor control system flexible and simple, and DSP is good at high-speed operation, so it is generally used in relatively high-end control systems, such as servo motor control. FPGA shows excellent performance in high-end motor applications. It realizes fast response, multi axis simultaneous processing, flexible and diverse peripheral interfaces, and support of a variety of industrial buses
for the different requirements of motor control, the inherent programmability and parallel processing characteristics of FPGA chip are very suitable for medium and high-end motor control applications. Because it carries out parallel processing in the way of pure hardware and does not occupy CPU resources, it can make the system achieve high performance. At present, the development of motor control tends to be more and more diversified and complex, and the field also puts forward more and more stringent performance requirements. Therefore, customers may consider developing their own special control chip, and the programmability of FPGA can meet this demand
at present, most products consider current loop control as a co processing of DSP, while speed or position loop control is realized by DSP chip. In general, because the position control is flexible and the difference is large, it is difficult to achieve versatility, so the position loop is usually directly completed by DSP; However, the speed and current loops are relatively universal and closely related to each other, so that high-performance speed control cannot be separated from current control, so they can be completely integrated into a chip for processing. In this way, speed servo control can be realized, current control can be carried out alone, and position servo system can be formed together with DSP. Xilinx FPGA also provides a 32-bit MCU microprocessor, which can further control the position, speed and current by one FPGA. Customers can fully customize a SoC chip to meet special needs. And once the trial production is successful, if you want to mass produce, you can also directly customize ASIC chips according to the FPGA design to reduce costs. In addition, FPGA also acts as the co processing function of MCU/DSP in many occasions, and also plays a very important role in combinatorial logic, bus and interface expansion
in addition, with the improvement of process technology, FPGA chips also show more and more obvious advantages in power consumption and cost. The spartan-6 series recently launched by Xilinx company is based on 45 nm technology, which is very suitable for industrial control applications. It integrates advanced technologies such as DSP hard core, storage controller hard core, PCIe hard core, etc. customers can realize vector control algorithm and high-speed interconnection to meet the requirements of complex servo systemsAs a function of MCU/DSP coprocessor, FPGA has been widely used in most motor control products, providing functions such as logic, interface expansion and bus. At the same time, the third party of Xilinx, such as anfuli, the authorized agent of Xilinx, also provides a large number of peripheral interfaces and industrial bus IP cores, enriching the application in the field of motor control
Xilinx will launch a reference design based on AC motor vector control in the near future, and provide a demonstration board and FPGA source code. Customers can develop products suitable for their own applications on this platform. We also plan to provide motion control engine and algorithm implementation of direct torque control, so as to provide customers with more choices to meet the needs of higher performance on site
our FPGA chip has been widely used in high-end CNC machine tools, high-end servo systems, high-end frequency converters, laser marking machines, and robot products. Foreign large enterprises such as Siemens, Ge, abb, etc. mostly use FPGA as the core processing platform to realize a SoC solution. At present, the research and development level of domestic enterprises in high-end servo products is still far behind that of foreign countries, but we believe that FPGA will play an increasingly important role under the industrial policy of the Chinese government to encourage domestic enterprises to develop their own intellectual property rights
now, the market has widely used motor control in emerging markets, so it also puts forward different requirements for motor controller/driver. The new design for AC and DC motor control must have the following characteristics: high efficiency, low power consumption as far as possible; The working time is long and the performance is not affected
traditionally, embedded system designers have been considering MCU + ASSP solutions. However, by using solutions that combine MCU, analog peripherals, embedded flash memory, programmable logic, and real single-chip operation (such as smartfu operating environment up to ⑶ 0 ℃ to 55 ℃ sion), designers can now achieve the high level of integration that previously only customized solutions could achieve
smartfusion intelligent mixed signal FPGA has an important impact on the operation of the system. Because armcortex-m3 processor is a standard unit module separated from FPGA architecture, the two can operate independently. Therefore, there is no need to interrupt the operation of the processor when the FPGA architecture is reprogrammed. This also allows the processor to update the functions of user logic as needed while handling critical system functions. Similarly, user logic can continue to operate during processor firmware updates
the intelligent mixed signal FPGA provides the following performance advantages: customizable robust PWM, realizing more precise control algorithm; Compared with software solutions, it has a faster and more deterministic control system, so as to reduce current ripple and noise; Immediately respond to user I/O (such as emergency braking alarm); Hardware acceleration of control algorithm; High speed flash memory can access lookup tables faster
actel's DSP design process allows designers to evaluate algorithms at a high level of abstraction using MATLAB and Simulink, together with a complete set of dsplockset and actelip. DSP designers can now use our industry-leading tool set to run a seamless and intuitive design process to interpret, optimize and verify RTL level, logic gate level and physical level designs
the use of smaller and more cost-effective motors in traditional motor applications has gradually become an important factor in the use of electronic motor control technology in the industrial field. Smartfusionfpga can provide embedded system designers who need real system on chip (SOC) solutions with greater flexibility than traditional fixed function microcontroller solutions, and the cost is much lower than traditional FPGA solutions with embedded soft core processors
smartfusionfpga provides a low-power, single-chip solution to optimize slip frequency control in AC induction motors. It integrates CPU, NVM, ADC and analog interface, enhances the control loop, improves efficiency, reliability and energy saving performance, and makes the motor have higher efficiency and lower power consumption. In addition, large capacity embedded nonvolatile memory can provide the required security to protect customized control algorithms