To achieve energy efficiency, ceiling fans and ventilation fans are moving from simple alternate-current (AC) induction motors to brushless direct-current (DC) motors (BLDC). An AC-operated BLDC motor requires two sections to run the BLDC motor: the AC-DC power conversion section and the DC to 3-phase AC conversion section. The Texas Instruments reference design, TIDA-00652, helps to meet these challenges of higher efficiency and power factor in a simpler way by using a single-stage power supply to convert the AC mains input into a low-voltage DC output. This reference design also combines a fully integrated and well protected single-chip, DRV10983, sensor-less sinusoidal brushless motor controller for low-noise operation.
For the DRV10983 device, the motor can be controlled directly through PWM, analog, or I2C inputs. With the physical arrangement of ceiling fans, the speed control of an AC-operated BLDC motor can be possible with an infrared (IR) remote or any high-end wireless control. The speed can also be varied with a change in the supply voltage of the DRV10983 device, but with the variation of AC over universal range, the output of AC-DC is regulated to 24 VDC. Therefore the speed of the fan is controlled by providing a fixed DC or PWM signal at the SPEED pin of the DRV10983 device. The speed of the fan can also be controlled using the I2C input of theDRV10983 device, as demonstrated in the TIDA-00652 reference design.
This application report presents two different ways to control the AC-operated BLDC ceiling fan with existing infrastructure. The first solution is to vary the speed by only toggling the AC mains switch. The second solution is to vary the speed using the TRIAC component similar to an existing AC-operated ceiling fan.
All trademarks are the property of their respective owners.
Figure 1 shows a basic block diagram for an AC-operated BLDC ceiling fan demonstrated using the TIDA-00652 reference design.
With the addition of a proposed circuit to the existing solution, the speed can be controlled by only toggling the AC mains switch. The proposed solution can completely eliminate the option of a remote to reduce the cost of the microcontroller (MCU), remote, and IR receiver. These devices can be replaced by a low-cost solution based on a ring counter (TI's CD74HC4017 device) and inverter (TI's SN74HCT14 device) which varies the speed by only toggling the AC mains and avoids the cost of a TRIAC component which are used in conventional ceiling fans. This solution can also be used along with the IR remote solution and can be used as additional control in case of the remote is lost.
In addition, using the proposed solution, an arrangement of sequence LEDs can be implemented on the surface of the fan to indicate the speed of the fan. Figure 3 shows this modification of the proposed solution.