Today the universal motor is still widely used in home appliances such as vacuum cleaners, washers, hand tools, and food processors. The operational mode, which is used in this application, is closed loop and regulated speed. This mode requires a speed sensor on the motor shaft. Such a sensor is usually an incremental sensor or a tachometer generator. The kind of motor and its drive have a high impact on many home appliance features like cost, size, noise, and efficiency. Electronic control is usually necessary when variables speed or energy savings are required. MCUs offer the advantages of low cost and attractive design. They can operate with only a few external components and reduce the energy consumption as well as the cost. This circuit was designed as a simple schematic using key features of a Kinetis L MCU. For demonstration purposes, the Freescale low cost Freedom KL25z development platform was used.
This application note describes the design of a low-cost phase angle motor control drive system based on Freescales’s Kinetis L series microcontroller (MCU) and the MAC4DC snubberless triac. The low-cost single-phase power board is dedicated for universal brushed motors operating from 1000 RPMs to 15,000 RPMs. This application note explains both HW and SW design with an ARM Kinetis L series MCU. Such a low-cost MCU is powerful enough to do the whole job necessary for driving a closed loop phase angle system as well as many others algorithms.
-Freedom development platform with universal motor drive board extension
The phase angle control technique is used to adjust the voltage applied to the motor. A phase shift of the gate’s pulses allows the effective voltage, seen by the motor, to be varied. All required functions are performed by just one integrated circuit and a small number of external components. This allows a compact printed circuit board (PCB) design and a cost-effective solution.
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Get the full application note in the link bellow: