This article describes the use of STM's latest Cortex-M4 core MCU with the FOLI single-resistance sensorless application based on the SLLIMM-nano second-generation series power modules in the refrigerator. With the vigorous promotion of national energy efficiency policies, more and more motor applications such as washing machines, fans, dishwashers, and range hoods have begun to sample frequency conversion technology. In the traditional motor drive, the use of discrete components leads to the reproduction of the system design structure, and the reliability is reduced. STMicroelectronics has developed a compact and reliable power module product for low-power motor applications. SLLIMM (Small Low-Loss Intelligent Molded Module) small low loss intelligent integrated module. There are two series in this module, SLLIMM series and SLLIMM-nano series. The SLLIMM series is 600V, 10A to 30A, and the SLLIMM-nano II is 600V with 5A.
software design
The STM32F302C8T6 is the latest STM-based Cortex-M4 core (with 8MHZ RC for 16 phase-locked loop multipliers) with FPU (maximum frequency 72MHZ). For high-performance motor drive applications, it integrates a dedicated circuit for the motor. Controlled Advanced TImer, with a maximum operating frequency of 128MHz, thanks to the powerful computing power of the Cortex-M4 core, an internal 8.2MHz high-speed op amp module. Powerful processing core, internal integrated high-speed op amp is enough to meet the requirements of field-oriented control (FOC) for real-time data calculation, cost-effective and competitive.
For common embedded permanent magnet synchronous motors (I-PMSM), such as refrigerator compressors, it is usually necessary to do a full-pressure start, which will require the compressor to start successfully in a short time under heavy load, such as drum washing, hood There will be similar work scenarios, so ST introduces high-frequency injection (HFI - High Frequency InjecTIon) based on the powerful computing power of Cortex-M4, ensuring that the compressor can start smoothly at zero speed under heavy load conditions. Enter normal operation mode. The HFI function needs to be implemented based on the FOC SDK 4.0 provided by STM. At the same time, STM also provides an easy-to-use configuration and online real-time debugging software ST Motor Control Workbench on the PC side for users to quickly get started (such as figure 1).
Figure 1 ST Motor Control Workbench GUI
To use the HFI function, you need to open the GUI interface and select “Internal PMSM†in the motor type selection (currently HFI only supports Ld).
Figure 2 Motor Body Feature Parameter Configuration Dialog Box
Go to the Driver Management Module page by clicking “Driver Management†on the right side of the GUI. Select “Speed ​​PosiTIon Feedback Management†from the page that appears. In the pop-up dialog box, select the “Main sensor†tab and use the “Sensor SelecTIon†drop-down selection box. Check " Sensor-less ( HFI + Observer )" (Figure 3).
image 3
At the same time, in order to meet the debugging requirements of HFI, we also need to enter the “Control Functionality†on the right side of the GUI to enter the “DAC Functionality†dialog box, and cooperate with the two DAC modules that come with the MCU to output the current and electrical angle signals required for debugging (Figure 4 ).
Figure 4
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