[Introduction]With the improvement of people’s health awareness, smart cleaning appliances are becoming more and more popular, and users’ requirements for the size, power, and portability of vacuum cleaners are also gradually increasing, especially wireless vacuum cleaners.

However, most of the vacuum cleaner motors on the market are series-excited AC motors and permanent magnet DC brush motors. The service life of these two types of motors is closely related to carbon brushes: short life, large size, large weight and low efficiency, and they are not very good. to meet market demand. Coupled with the impact of the battery, it is not easy for the vacuum cleaner to “shake the braid”.

Based on the new requirements of vacuum cleaners for motors with small size, light weight, long life and high performance, the brushless DC motor (BLDC) has the characteristics of long life and easy control, which well meets the needs of multi-application integration in the design of vacuum cleaners. Personalized vacuum cleaner design offers more possibilities.

● The high efficiency of a BLDC motor is reflected in the fact that its swirling force (torque) can be controlled to always keep the maximum value; therefore, the BLDC motor can obtain the required torque and number of revolutions exactly, and suppress the motor by precise control heat and power consumption. If the battery is driven, the driving time can be extended through careful control. In addition, it has the characteristics of durability and low electrical noise.

● BLDC motors for industrial applications are designed to provide a protected, high-efficiency, small-scale solution, where a three-phase bridge switching circuit is the core, and its control typically uses a microcontroller (MCU) or other ASIC to coordinate its switching to meet precise requirements switch timing requirements. This can be challenging because most MCU outputs are not optimized for driving power transistors. Therefore, it is beneficial to shorten the duration of the transition period by charging and discharging the gate capacitance faster. A gate driver is a circuit that amplifies a control signal from a microcontroller or other source so that it adapts to the efficient operation of a semiconductor switch.

● The precise control of the motor and its subsequent adjustment have high requirements on the MCU, which also has certain requirements on the dead time and the variability of the input signal. The solution given by Renesas is: intelligent gate driver BLDC motor control.

System advantage

● Allows the use of a minimalist MCU, without the need for a three-phase coupled S/H circuit for current sensing;

● The input signal of PWM consists only of PWMhi signal, and PWMlo with adjustable dead time is generated by gate driver;

● Wide range of motor functions: voltage 5~60V, maximum current 2A.

System Block Diagram

target application

● Ventilators/fans

For ventilators and fans, changing the air volume and air pressure of the ventilator to meet the requirements of changing operating conditions is called performance adjustment. Among the commonly used adjustment methods, in terms of economic performance, this method of changing the fan speed is better, but more complicated. The impeller strength and motor load conditions need to be considered when changing the speed.

● vacuum cleaner

There is a fan attached to the motor of the vacuum cleaner. The electric exhaust fan runs at high speed after being energized, so that an instant vacuum is formed inside the vacuum cleaner. The air pressure inside is much lower than the air pressure outside. Under the action of this air pressure difference, dust and dirt enter with the airflow. The vacuum cleaner barrel is filtered by the dust bag, and the dust remains in the dust bag, and the purified air escapes into the room through the motor, which cools the motor and purifies the air.

● heater system

With the development of power Electronic technology and BLDC motor, the heater system has gradually changed from “AC frequency conversion” to “DC frequency conversion”. In the current process of ultra-high voltage DC power transmission and transformation, because under the condition of certain power, the greater the current, the greater the loss. “Ultra high voltage-DC” can achieve the purpose of energy saving and environmental protection.

Combination element

● RAA227063 is a smart gate driver IC for BLDC motor applications. It integrates three half-bridge smart gate drivers capable of driving up to three N-channel MOSFET bridges and supports bridge voltages from 4.5V to 60V. Each gate driver supports up to 1A source current and 2A sink peak drive current with programmable drive strength control.

The RAA227063 implements adjustable and adaptive dead time to ensure robustness and flexibility. The active gate retention mechanism prevents the cross-conduction caused by the Miller effect and further enhances the robustness.

● MOSFETs are suitable for switching (motor drive, etc.) and load switching applications, with low on-resistance, high-speed switching and high robustness.

● The RA2E1 product group is the RA family of entry-level single-chip microcontrollers based on the 48MHz Arm® Cortex®-M23 core with up to 128kB of code Flash and 16kB of SRAM. Using an optimized process and Renesas’ low-power process technology, this product is an industry-leading ultra-low-power microcontroller. RA2E1 products support a wide operating voltage range of 1.6~5.5V and a variety of packages such as LQFP, QFN, LGA, BGA and WLCSP. The RA2E1 is pin and peripheral compatible with the RA2L1 product group, making it ideal for battery-operated and space-constrained applications, as well as other systems requiring high performance and low power consumption.

This solution provides more possibilities for motor applications, unifies practicality and portability, and helps to further expand the corresponding market.