A vacuum cleaner design integrates a microcontroller, advanced infrared functionality, and intelligent suction management.
Today’s vacuum cleaner is an essential home tool. The upright and canister models are its two primary forms. While upright vacuums are popular in the US and UK, canister types dominate the European market. To simplify the design process NXP Semiconductor has launched the reference design for a vacuum cleaner that uses a universal motor, meaning that the motor can operate from an ac or dc supply. Vacuum cleaner motors can reach speeds of up to 30,000 RPMs. This rapid operation is essential to produce potent suction with a compact fan. In contrast, an induction motor’s speed is capped at 3600 RPMs.
The reference design is based on the HC908KX8 microcontroller unit (MCU), which produces the triac drive waveform and regulates the motor’s speed. Microcontrollers enhance these advanced models by incorporating features like infrared or wired remote controls, status LED indicators, and automated suction management. A potentiometer adjusts the motor speed, with the MCU gauging the potentiometer through an analogue-to-digital converter (ADC) port pin. Current injection into the MCU is controlled using a high-value resistor. To drive the triac directly, four-port pins provide adequate sink current. A charge pump power supply powers the MCU and the trial’s drive current. This power supply method is effective only up to roughly 20 mA, with its supply current determined by the AC line capacitor’s size. However, a basic charge pump power supply needs the current capacity to power status LEDs. To reduce the triac drive current, a sensitive gate triac can be employed.
The design of the vacuum cleaner incorporates phase angle control, which entails delivering only a section of the AC waveform to the load. The primary function of the phase angle control software is to generate the trigger pulse for the triac. The software has been developed for basic vacuum cleaner universal motor control. The design also features an internal oscillator and a small 16-pin package. The software is compatible with the internal oscillator or other low-cost RC oscillators. The reference design has eight Kbytes of FLASH memory, ample for a modest program. The phase angle control software occupies just around 1.2 Kbytes of this memory. The peak current of the vacuum cleaner motor design is approximately 40 amps.
NXP has tested this reference design. It comes with a Bill of Material (BOM), schematics, etc. You can find additional data about the reference design on the company’s website. To read more about this reference design, click here.
