DESC:Prior Art Draw back :

In general, Wall mounted regulator are not suitable for BLDC fan, the reason being that a Generic controller cannot keep the fan rotation in desired speed step as there will not be specific detection of input voltage based on regulator capacitance .

Object of the invention :

A new novel technique in Hardware and firmware is proposed and being developed to achieve performance of BLDC motor with Generic wall regulator makes and models.

The other objects of the invention are :-

Feature rich and high performance fans is the aim of the invention which is based on (MCU) microcontroller based intelligent, variable speed control, brushless DC (BLDC) fans.

BLDC enabled fans which exhibit variable speed control, low acoustic noise, reliability, long life time, low power consumption, protection features, easy to maintain/upgrade and communication interface capability are the essential novel characteristics shall be exhibits by these novel MCU based BLDC operable fans.

The other object is to create a novel algorithm which is variable speed control algorithms for BLDC fan, which include methods for acoustic noise reduction, power consumption consideration, and communication interface.

The other objectives is to offer a flexible, simple, cost effective MCU based solution, as cost of MCU is low and unique speed control algorithms may be used to be adopted in the MCU solution.

Description of invention :

Typically the physical appearance of conventional and BLDC fans are basically the same. Both types of fans also do operate on the principle to convert electrical energy to mechanical motion. The fan rotates when a DC voltage is applied to its terminals. The speed of the fan depends on the applied voltage across the terminals.

But the internal construction is significantly different between conventional and BLDC fans but both fans do require the commutation that allows the direction of current flowing through the fan windings to reverse every 180° of rotation.

In a typical DC fan systems, the stator of the permanent magnet is composed of two or more permanent magnet pole pieces and rotor is composed of windings that are connected to a mechanical brush referred as commutator. The stator magnets and the opposite polarities of the energised windings attract the rotor and rotor will rotate until it is aligned with stator. At that instant, the brushes move across the commutator contacts and energise the next winding, and thereby the fan rotor rotates continuously.

But this is not so in BLDC fan. In this stator is a classic two-phase stator and rotor will have surface mounted permanent magnets. Hence BLDC fan is a rotating electric machine. This means BLDC fan is equivalent to a reverse conventional DC fan, the current polarity is altered by the “electrical commutator” instead of “mechanical brushes: Hence unlike conventional DC fan which suffers higher inertia due to bulky rotor coils, BLDC fans operate with a lighter rotor due to its permanent magnets.

To control the variable speed in BLDC fans, these are external and internal approaches available. In external approach is it is done by connecting external transistor/FET in series of the BLDC fan (high side/low side) to control the supply voltage across fan, by using linear regulator or by using DC-DC regular or by using pulse-width modulation (PWM) driving methods. The speed of BLDC fan is direct proportion to supply voltage.

The other approach is internal approach which is using “Built-in internal transistors/FETs inside the BLDC fan”. The change in speed by ASIC solution ensures rigid but with least flexibility as speed control method and hardware configuration pins are defined and fixed. This is easy to implement but suffer lack of flexibility.

The other solution is MCU solution, in which many speed control algorithms can be adopted. The two methods generally are known as phase on/off time delay method and PWM control method.

Hence it can be understood that a BLDC motor is a synchronous electric motor powered by DC electricity and having an electronic commutation system, rather than mechanical commutator and brushes. In BLDC motors, current to torque and voltage to rpm have “linear” relationships. This linearity provides an opportunity to use “BLDC motor” in the “conventional ceiling fans”. This invention hence presents practical implementation of such BLDC motor for ceiling fan application along with the actual power measurements in comparison with conventional ceiling fans. Further BLDC motor, a controller is always required and BLDC motor has rated starting current.

BLDC fans are isolated from input supply voltage/voltage fluctuation. BLDC ceiling fans require electronic hardware with a microcontroller to run the motor. In BLDC motors, it is the electronic hardware that supplies the input voltage to the motor and it is “constant”. So typically the input supply voltage at the “mains” is decoupled from the BLDC ceiling fan motor. It is isolated from main voltage and it receives the constant voltage supplied by the electronic hardware.

The speed of the fan is dependent on the voltage of the voltage regulator connected to the ADC pin of the MCU. The ADC allows the microprocessor controller circuits to communicate with the real world (convention regulator).

In conventional fans as we go on changing the position on knob from position 1 to position n, the series resistance keeps on decreasing and hence the voltage applied to the fan increases and so does the speed of the fan.

As per invention, in BLDC fans, there is a need to find a solution, which solution will be such that it is flexible to be adapted to capture the signals of the “conventional regulator” and give corresponding input to the BLDC motor, as it is immune to the “conventional regulator” selection of the user.

As there will be multiple makes and models of wall regulator in market / the end user, as per solution offered by this invention is to identify the wall regulator step position with unique Potential difference detection impedance check method.

As per the invention, in this method regulator output voltage is sensed for various conditions. For every position changes the unique algorithm will detect the no load voltage and load condition voltage. The differential voltage will define the regulator impedance.

As per this invention additional load is provided typically by adding 60 watt dump load for 2sec.This dump load is activated through a solid state switch and controlled by MCU. The dump load is typical, as per products in the market. The numerical value mentioned is merely for understanding and is not limited by the actual value mentioned herein.

The novel features of the invention are :

1. Hardware is incorporated to detect no load voltage and load voltage to aid MCU to detect regulator impedance.
The hardware has following components :-
EMI filter & Rectifier
Fly Back Converter
24V to 5V DC Converter
MCU
FET Driver
Electronic Switch
Relay Drive
2. A unique Fuzzy logic according technique is used to detect this no load and load voltage and MCU will compute impedance and switch the motor in a particular speed step according to the table defined internally

Working Principle :
Figure of content:
Fig. 1 Block Diagram
Part no. Part Name
101 P
102 Regulator
103 N
104 EMI Filter
105 Regulator Position Check
106 Fly-Back DC-DC
107 24-5V-DC-DC
108 MCU
109 FET Driver
110 Buzzer
111 Motor
112 Regulator Impedance Check Triggering Pulse
113 Regulator Impedance Check Feed back

Fig. 2 Regulator based Ordinary Induction Ceiling Fan
Part no. Part Name
201 N
202 P
203 Wall Regulator
204 Auxiliary Winding
205 Main Winding
206 Capacitor
207 Induction FAN

Fig. 3 Regulator Position & Fan Motor terminal voltage Graph
Part no. Part Name
301 Fan Motor Voltage (V)

Fig. 4 Challenges for Regulator based BLDC Fan
Part no. Part Name
401 P
402 N
403 Regulator
404 SMPS & BLDC Driver Board
405 BLDC Fan

Fig. 5 Regulator Position & Input terminal voltage Graph
Part no. Part Name
501 Fan SMPS input voltage (V)

Fig. 6 Design for Regulator based BLDC Fan
Part no. Part Name
601 P
602 Regulator
603 N
604 EMI Filter & Rectifier
605 Fly-Back DC-DC
606 24-5V DC-DC
607 MCU
608 FET Driver
609 Buzzer
610 Motor
611 Electronic Switch
612 Switch Driver
613 Dump Load

Fig. 7 PDD method flow chart
Part no. Part Name
701 Start
702 Wait for 2 Sec
703 Read no Load ADC
704 Turn on Dump Load
705 Wait for 2 Sec
706 Read Dump Load ADC
707 Find the Position
708 Set the motor at Actual position
709 Turn on Load
710 Is 10 sec Expired?
711 Read Load ADC
712 Change Detected in Regulator Position
713 Recheck the Position

Fig. 8 BLDC Fan Driver
Part no. Part Name
801 Supply
802 SMPS
803 Inverter
804 Motor

Fig. 9 Hardware of PDD technique wall BLDC Fan Driver

Description :
Fig. 1 Block Diagram :-
Regulator is work as a controller of fan. The controller yield given to the EMF channel and Controller Position checker. EMF filter give an output to the MCU, Flyback DC- DC Converter and get a regulator impedance feedback in digital signal like Triggering pulse Fly back DC- DC Converter to change over 325v Dc to 24v Dc, this 24v given to FET Driver and DC-DC converter, this DC- DC converter to change over 24v Dc to 5v Dc. The 5v is given to the MCU. Micro controller Unit is the main unit to perform all over the operation of Regulator control.
Fig. 2 Regulator based Ordinary Induction Ceiling Fan :-
According to double field revolving theory, an alternating flux can be separated into two fluxes which rotate initially in opposite direction. A single phase induction motor can be started by adding an auxiliary winding and a capacitor connected in series to it. To start a single phase AC induction motor, two phases are needed to produce the rotating magneto motive force (MMF) but we have only one phase due to single phase AC supply in our homes. Therefore, we require an additional phase to start these kinds of motors. We get the second phase by adding a capacitor in series with the starting wind of a ceiling fan motor, so we move to BLDC Fans.
Fig. 3 Regulator Position & Fan Motor terminal voltage Graph :-
An adjustable voltage regulator is a kind of regulator whose regulated output voltage can be varied over a range. When we set a regulation position at 0 to get 0 Voltage, to change a position at 1 we get around 110v, to change a position at 2 we get around 140v, to change a position at 3 we get around 180v, to change a position at 4 we get around 200v, to change a position at 5 we get around 230v.
Fig. 4 Challenges for Regulator based BLDC Fan :-
The three legs of the electrical coils as indicated are excited through the PWM technique so at any point, two of them are applied with the positive and the negative waveforms of the PWM output whereas the third is non-energized .In essence we have two components required for the BLDC motor control: One is the PWM generation and control electronics for the BLDC motor and the other is the DC voltage generation based on the AC mains. In the proposed BLDC motor based ceiling fan solution, the DC power is supplied through an SMPS which converts the AC mains supply to DC voltage. The electronics of the BLDC Motor controller as such has the ability to either take the 24V DC from battery or from AC Mains and the SMPS design (AC DC converter module) allows varying AC voltage to be used as input while keeping the constant DC output, as desired. Speed control of the motor is achieved through the remote.
Fig. 5 Regulator Position & Input terminal voltage Graph :-
When we set a regulation position at 0 to get 0 Voltage, to change a position at 1, 2, 3, 4, we get around 200v, to change a position at 5 we get around 230v (Maximum Voltage)
Unreadable input voltage changes happening, due to variable motor impedance and Variable regulator impedance.
Fig. 6 Design for Regulator based BLDC Fan :-
EMI filter:
Regulator Connect earlier than in collection because of regulating purpose (act like a Resistance).The EMI filter (electromagnetic interference filter) is a filter circuit composed of a capacitor, an inductor and a resistor. Its function is to reduce high frequency electronic noise that may cause interference with other devices.EMI filter, a square wave group or composite noise passing through the power supply filter can be converted into a sine wave of a specific frequency.EMI filters are devices or internal modules designed to reduce or eliminate noise interference.
Fly Back Converter:
Input : 325V DC Supply
Output: 24V DC Supply
This transformer gives an advantage of voltage control at secondary and also we can drive many different output voltages. Fly back converter is an isolated power converter and provide isolation between primary and secondary side. The current flowing from the transformer charges the capacitor at secondary side and supplies the energy to the connected load. A Fly back Converter is an important power converter used in switched-mode power supplies to meet our low voltage requirements. Our DC – DC converters are designed using this topology because of provision of isolation between primary and secondary winding. Also, it provides good output efficiency, which means less loss.
24V to 5V DC Converter:
Input : 24V DC Supply
Output: 5V DC Supply
This Buck Converter is designed to provide 24V to 5V power conversion for MCU Operating purpose. It provides High efficiency, high precision DC–DC Converter unit, Over voltage and current protection.
MCU:
It is a Main control Unit to control the performance of the entire unit to interface with that. An MCU is an intelligent semiconductor IC that consists of a processor unit (FET Driver), communication interfaces and peripherals (Buzzer). MCU is a 48 pin Micro controller and it has Over Voltage Protection circuit. All over the Software code programmed here to Performing an Operation.
FET Driver:
Input : 24V DC Supply, PWM Signals
Output: DC to AC Conversion
A MOSFET driver allows a low current digital output signal from something like a Microprocessor to drive the gate of a MOSFET. A 5 volt digital signal (PWM) can switch a high voltage MOSFET using the driver. MOSFET driver input can be a pulse signal. It will lead to fast speed and small ground bounce.
Electronic Switch:
Electronic switching device is a combination of active switchable power semiconductor drivers that have been integrated into one. The main characteristics of the switch are determined by internal correlation of functions and interactions of its integrated system. Switching devices are normally selected based on the rating at which they handle power, that is, the product of their current and voltage rating instead of their power dissipation rate. This circuit is used to control the speed of a BLDC motor through a technique called pulse width modulation. The speed of the motor will depend on the average voltage applied to it. This applying a continuously variable voltage to the motor, we instead apply a series of pulses of varying width. These pulses are so fast that the motor does not start and stop, but rather inertia keeps it going. Instead, the motor responds to the averaged value of these pulses. If the pulses are narrow and widely spaced, the average value will be low and the motor speed will be slow. If the pulses are wide and closely spaced, the average will high and the motor speed will be fast.
Dump Load:
Dump Load is a Dummy Load connected to the supply to check an initial performance. Dump load consume 60W power.
Fig. 7 PDD method flow chart :-
Step 1: Power supply is given to the Hardware.
Step 2: When the Power supply is on wait for 2 second and read the No Load Analog to Digital Converter
Step 3: Then connect the Dummy Load and wait for 2 second and read the Dummy Load Analog to Digital Converter to find the position.
Step 4: This Position is Motor’s Actual Position. Set that Motor at Actual Position
Step 5: After that to connect the Load, Wait for 10 sec to reconfirm the position
Step 6: If the condition is true recheck the position and Set that Motor at Actual Position
Step 7: If the condition is false Read the Load Analog to Digital Converter and check Change Detected in Regulator position.
Step 8: If any Change Detected in Regulator position. Set that Motor at Actual Position
Step 9: If No Change in Detected in Regulator position. Wait for 10 sec to reconfirm the position.
Step 10: To Repeat the step 6 to 9.

Fig. 8 BLDC Fan Driver :-
SMPS is used for convert ac supply into dc supply and maintaining the unity power factor. Inverter is doing the motor commutation process which is driving the motor. Our entire goal is based on the regulator position need to change the motor speed.

Ceiling fan has a single-phase electric motor and blades connected to it. When given a supply to motor, unable to provide torque to rotate it. Therefore, a start capacitor is provided across one of the two windings. This goes out of circuit once the motor starts. For fan speed control regulators are used (Table 1).

General specification for Ordinary Ceiling Fan
Fan Motor Type Capacitor type single phase Induction motor
Capacitor rating 2.0mfd. , 440V, 50Hz, A.c.
Rated Voltage 240 V
Rated Power input 72 Watts
Rated Current 0.33 A
Rated Power Factor 0.9
Rated Speed 380 RPM
Isolation 1.5 KV
Fan Load Impedance 727 Ohm
Table 1

There are three types of regulators available in the market, Capacitor regulator, Step type electronic regulator and Movable Electronic Regulator. All three types regulator have different ways of controlling the voltage by changing the fan speed. From a price and efficiency perspective, capacitor regulator is the cheapest.

Table 2 illustrates for capacitor regulator based induction fan operation:
SL:NO Input Voltage Regulator Position Regulator Capacitor (uF) Capacitor Impedance (Ohm) Fan Motor Power (W) Fan Motor Voltage (V) Fan motor Current (A)
1

230 0 - - 0 0 0
2 1 2.2 1447.597 16 107.872 0.1483
3 2 4.4 723.79849 27 140.13 0.1927
4 3 7.7 413.59914 45 180.907 0.2487
5 4 11 289.5194 55 200 0.275
6 5 - 0 75 230 0.3261

Table 2: Wall regulator for induction motor

The conclusion is that there is readable input voltage changes happened due to fixed motor Impedance and Variable regulator impedance. The input voltage change is critical parameter for fan speed control.

But for BLDC motor there is no brush use between rotor and stator for transferring electricity supply. Hence it’s called brushless dc motor and a regulator of conventional ceiling fan cannot be operated with BLDC fan for reasons mentioned above (refer Fig. 8)

A SMPS is used for convert ac supply into dc supply and maintaining the unity power factor. Inverter is doing the motor commutation process which is driving the motor. The entire goal is based on the regulator position need to change the motor speed, wherein adaptation is the core essential portion of this invention.

Table 3 illustrates capacitor regulator based BLDC fan operation:
SL:NO Input Voltage Regulator Position Regulator Capacitor (uF) Capacitor Impedance (Ohm) Input Power (W) Input Current Load Impedance Fan SMPS input voltage(V)
1 230 0 - - 0 0 - 0
2 1 2.20 1447.5 6 0.026 8816.6 197.5
3 2 4.40 723.7 12 0.052 4408.3 197.5
4 3 7.70 413.5 18 0.078 2938.8 201.6
5 4 1.10 289.5 24 0.104 2204.1 203.2
6 5 - 0 36 0.156 1469.4 231

Table 3: Wall regulator for BLDC Fan

For conclusion there are unreadable input voltage changes happening, due to variable motor impedance and Variable regulator impedance. Hence that regulator position detection is very difficult in this method.

As per the invention the design consists of SMPS, motor FET driver and in addition to that a new novel technical is included which is “Predict control impedance check method. This is identifying the regulator impedance. In this method, the proposed algorithm will detect the no load voltage and dump load voltage. The differential voltage will define the regulator impedance.

The novel technique includes hardware, firmware and software. The details in terms of physical / structural arrangement and details in terms of operational / functional arrangement are given below:

Hardware:
Fortior Micro Controller
Motor driver
SMPS
Software:
Embedded C
KEIL
Firmware:
FOC Algorithm

Table 4 illustrates the differential voltage reading for regulatory changes:
Supply Voltage Regulator Position Regulator output Voltage Dump Load On Condition Voltage Difference Voltage
230 1 194 157 37
2 197 180 17
3 202 192 10
4 206 199 7
5 230 230 0

Table 4: Capacitor impedance observation

Difference voltage obtained for all type standard wall regulators is illustrated in Table 5.

Regulator Position Minimum Difference Voltage Maximum Difference Voltage
1 20 40
2 12 19
3 9 11
4 5 8
5 0 4
Table 5: Capacitor impedance observation

In conclusion this unique combination of impedance check hardware and firmware is referred as Predict control impedance check method. This method can support all type of market regulators and supporting operating voltage will be 170VAC to 265 VAC.

The invention teaches a method to control the variable speed in wall mounted BLDC ceiling fan associated with a conventional regulator, with detection of input voltage as speed of a BLDC fan is direct proportion to supply voltage comprising of electronic hardware supply means of constant support input voltage to the motor whereby input supply voltage at the “mains” is decoupled from the BLDC ceiling fan motor. It has a Micro controller Unit with a ADC pin which ADC pin of MCU is adapted to communicate with convention regulator of the wall mounted BLDC ceiling fan wherein change of position on knob from position 1 to position n, the series impedance decreases and hence voltage applied to fan increases and thereby increasing the speed of the fan. Further the arrangement has a fuzzy logic adapted to detect the no load and load voltage of the control regulator and associated corresponding input given to MCU, which MCU will compute the impedance and accordingly switch the motor in a particular speed, based on the differential voltage so computed by MCU, and a dump load controlled by MCU and it was operating based on supply voltage changes.
It should be noted that any one of the foregoing embodiments is illustrative and not limitation of the present invention and therefore, various changes and modifications are possible within the scope of the present invention. The applicant relies upon the provisional specification and drawings filed in this application and shall be considered as part and parcel of complete specification.
,CLAIMS:WE CLAIM :
1. A method to control the variable speed in wall mounted BLDC ceiling fan associated with a conventional regulator, with detection of input voltage as speed of a BLDC fan is direct proportion to supply voltage comprising of :-
a. electronic hardware supply means of constant support input voltage to the motor whereby input supply voltage at the “mains” is decoupled from the BLDC ceiling fan motor,
b. a Micro controller Unit with a ADC pin,
c. the ADC pin of MCU adapted to communicate with convention regulator of the wall mounted BLDC ceiling fan wherein change of position on knob from position 1 to position n, the series impedance decreases and hence voltage applied to fan increases and thereby increasing the speed of the fan,
d. a fuzzy logic adapted to detect the no load and load voltage of the control regulator and associated corresponding input given to MCU, which MCU will compute the impedance and accordingly switch the motor in a particular speed, based on the differential voltage so computed by MCU, and
e. a dump load controlled by MCU and operating based on supply voltage changes.