Design Case (40mm Annular Control Board)
This application design simplifies and optimizes the sensorless control algorithm for Brushless Direct Current (BLDC) motors, which is typically implemented by Digital Signal Controllers (DSC) or high-end 16/32-bit microcontrollers. It achieves complete control functionality on the New Tang enhanced 1T 8051 core microcontroller, highlighting the overall cost-performance ratio of the product.
The algorithm utilizes a selective filtering function for digital filtering of Back-Electromotive Force (BEMF). By filtering each phase of the motor, it determines the timing for commutation of the motor drive voltage. This control technique eliminates the need for discrete low-pass filter hardware and external comparators (suitable for three-phase motors). The motor control algorithm consists of five main parts:
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Using the on-chip Analog-to-Digital Converter (ADC) to sample the trapezoidal BEMF signal
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Sampling the PWM on-state with the ADC to reduce noise and address low inductance issues
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Using the on-chip Analog Comparator (ACMP) to compare the trapezoidal BEMF signal with VBUS/2 for quick zero-crossing detection
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Filtering the comparison result signal with a selective filtering function
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Commutating the motor drive voltage in three different modes:– Traditional Open-loop Controller– Traditional Closed-loop Controller– Proportional-Integral (PI) Closed-loop Controller
Six-Step (Trapezoidal) Commutation
New Tang NuMicro® ML51 Low-Power Microcontroller
The New Tang NuMicro® ML51 Low-Power series features an enhanced 1T 8051 core microcontroller with built-in Flash, achieving typical power consumption of 80 μA/MHz in normal operation mode and less than 1 μA in sleep mode. This series can run at a maximum speed of 24 MHz and integrates various analog features, such as a 12-bit 500 Ksps SAR ADC and up to two sets of ACMP analog comparators, built-in four-order reference voltage for ADC and ACMP use, and up to four sets of DMA for accelerated data transfer to reduce CPU load. Additionally, the NuMicro® ML51 series includes rich peripheral devices, such as two sets of serial ports, two sets of I²C, up to two sets of ISO-7816, and two sets of SPI interfaces.
The NuMicro® ML51 low-power series has built-in Flash memory ranging from 16 to 64 KB and SRAM from 1 to 4 KB. It offers various package options from 10-pin to 64-pin, with pin compatibility with New Tang’s 32-bit Arm microcontrollers for easier selection and upgrades. Fully compliant with industrial specifications, the operating temperature range is -40 ℃ to +105 ℃.
Recommended Application Model ML51PB9AE（P-LQFP32 / B9-16 KB Flash）
Target ApplicationsApplication
BLDC motor control, handheld devices, smart remote controllers, network endpoints, smart homes, smoke detection, battery devices, etc.