DESC:FORM-2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)

Title: UNIFIED MICROCONTROLLER BASED MULTI-MOTOR CONTROL SYSTEM AND METHOD THEREOF

APPLICANT DETAILS:
(a) NAME: BHARAT ELECTRONICS LIMITED
(b) NATIONALITY: INDIAN
(c) ADDRESS: OUTER RING ROAD, NAGAVARA, BANGALORE 560045, INDIA

PREAMBLE TO THE DESCRIPTION:
The following specification (particularly) describes the nature of the invention (and the manner in which it is to be performed):

UNIFIED MICROCONTROLLER BASED MULTI-MOTOR CONTROL SYSTEM AND METHOD THEREOF

FIELD OF THE INVENTION:
This invention is related to the relates to the field of control system and more particularly to a unified microcontroller-based multi-motor control system and method thereof.

BACKGROUND OF THE INVENTION:
The following background discussion includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
A motor control system is one of the key components in any electromechanical systems. Control of the Brushless Direct Current Motor (BLDC motor) involves electronic commutation and closed loops. The BLDC motor provides many advantages over brushed DC motors and induction motors such as better speed-torque characteristics, high power density and long operating life. Due to these advantages, BLDC motors are used in unmanned mobile systems, automobiles, health care systems etc.
The BLDC motor includes permanent magnets as rotor, coil windings as stator and motor control system is used for its commutation and closed loop control. Commutation involves sequential switching and varying current among stator windings which rotates rotor continuously. There are three types of commutation approaches for controlling speed of the motor, namely trapezoidal commutation, sinusoidal commutation and field-oriented control (FOC).
Trapezoidal commutation is most widely used for controlling BLDC motor. This approach uses three current controllers for controlling current in stator windings. These current controllers cause torque ripple which are dominant during lower speeds. Such undesired torque ripple cause motor to vibrate and generate more noise which affects the smooth operation and precision.
The sinusoidal commutation does not cause torque ripple when BLDC motor operates at lower speeds, but it is inefficient in controlling output torque at higher speeds which affects smooth operation.
US Patent no. US11374520B2 relates to field - oriented sensor less brushless motor control in a power tool. The power tool is provided including a housing, a brushless motor disposed within the housing, a power switch circuit that supplies power from a power source to the brushless motor, and a controller configured to receive at least one signal associated with a phase current of the motor, detect an angular position of the rotor based on the phase current of the motor, and apply a drive signal to the power switch circuit to control a commutation of the motor based on the detected angular position of the rotor. If the supply of power to the motor is turned OFF to cause the motor to slow down and is turned back ON while the rotor speed exceeds a speed threshold, the controller electronically brakes the motor for a time interval to measure the phase current of the motor and detects the angular position of the rotor based on the measured phase current.
Another US Patent no. US10589011B2 relates to field-oriented control for control of blood pump motor. A ventricular assist device includes a pump configured to pump blood of a patient. A motor is configured to operate the pump. First, second, and third conductors are coupled to the motor and are configured to supply electric current from a power supply to the motor in first, second, and third phases, respectively. A controller is configured to operate the motor using a Field Oriented Control (FOC) method, and if one from the group consisting of first, second and third conductors becomes unable to supply electric current to the motor, the controller continues to operate the motor using the FOC method using the phases of the two conductors that are able to supply electric current to the motor.
FOC, also known as vector control, is a technique, which provides better control capability over full torque and speed ranges. This approach is efficient in controlling output torque of the motor at both lower and higher speeds. In this approach, magnetic fields of stator and rotor are orthogonal to achieve maximum torque. This approach uses decoupled control of flux and torque and helps the BLDC motor to rotate above nominal speed using field weaking technique. The FOC approach requires a high-cost controller with more processing capability as it uses complex algorithms, multiple current controllers and transforms.
Hence, there is a need for a cost effective, hardware efficient FOC based control system which ensures smooth operations and controls torque output of the BLDC motor efficiently at both lower and higher speeds.

OBJECT/S OF THE INVENTION:
The primary object of the present invention is to overcome the drawbacks associated with prior art.
In an objective the present invention provides a cost effective, hardware efficient FOC based control system which ensures smooth operations and controls torque output of the BLDC motor efficiently at both lower and higher speeds.

SUMMARY OF THE INVENTION:
In an aspect, the present invention provides a unified microcontroller based multi-motor control system comprising:
a) a master control unit (101) is configured to set a target speed of a motor;
b) a communication unit (102) communicable connected to the master control unit (101) receives the set speed of the motor;
c) a reference data extraction unit (103) receives the set speed of the motor is configured to convert into a reference data; and
d) plurality of motor control units (104, 105), where each motor control unit comprises of following units a position sensing unit (207), a speed estimation unit (205), an inverter (209), a current sensing unit (206), a speed control unit (201), a current transformation unit (204), a current control unit (202), a pulse width modulation (PWM) generation unit (203) and a fault monitoring unit (211);
wherein the speed control unit (201) is configured to calculate a reference quadrature axis current based on the target speed and an actual speed of the motor, where the actual speed is calculated from ta rotor position data given by a position feedback sensors coupled on to the motors.
In an embodiment, each motor control unit includes a cascaded control loop comprising a speed control as an outer loop and a torque control as inner loop.
In an embodiment, position sensing unit (207) identifies the sector of electric motor to which the rotor is pointing.
In an embodiment, the inverter (209) circuit converts direct current to an alternating current and comprises plurality of switches which regulate the alternating current supplied to the stator windings.
In an embodiment, the current sensing unit (206) measures the alternating current drawn by the coil windings when the rotor is pointed to the particular sector.
In an embodiment, the current transformation unit (204) takes input from the current sensing unit (206) and estimates quadrature axis current of the rotor.
In an embodiment, the current control unit (202) takes actual quadrature axis current input from the current transformation unit (204) and target quadrature axis current from the speed control unit [201] and estimates the duty cycle required to achieve target speed.
In an embodiment, the PWM generation unit (203) generates the modulated signals based on the estimated duty cycle to drive the inverter switches (like MOSFET, IGBT etc.) to incrementally vary the speed of the rotor to achieve target speed, where each speed control unit (201) and current control unit (202) have an individual proportional-integral (PI) controller.
In an embodiment, the fault monitoring unit (211) raises the alarm if any faulty condition is detected and switches off the supply to the inverter (209) during execution of a motor control and communicates the fault status to the master control unit (101).
In an aspect, the present invention provides a unified microcontroller based multi-motor control method comprising steps of:
a) receiving reference (target speed) data from the master control unit;
b) extracting the data and forwarding it to both motor control unit based on identifier;
c) identifying the sector in which rotor is positioned and alignment using feedback sensor input;
d) estimating speed error between target and actual speeds;
e) calculating the target quadrature axis current based on the speed error;
f) sensing and measuring the alternate current supplied from the inverter to the stator;
g) transforming the measured current to direct axis current and quadrature axis current;
h) calculating error between target and measured quadrature axis currents;
i) estimating the duty cycle of the PWM signal and generating PWM signal; and
j) measuring the actual speed from feedback sensors and incrementally varying it based on proportional-integral gain values till it reaches target speed.

DETAILED DESCRIPTION OF DRAWINGS:
The advantages and features of the present disclosure will become better understood with reference to the following detailed description and claims taken in conjunction with the accompanying drawing, in which:
Fig. 1 illustrates a block diagram of motor control system of the present invention.
Fig. 2 illustrates a block diagram of motor control units (Units 1 to N).
Fig. 3 illustrates a block diagram of Motor control system Architecture.
Fig. 4 illustrates a working principle (Flowchart) of motor control system.
It should be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative system and method of embodying the principles of the present disclosure. Similarly, it will be appreciated that any flow charts, flow diagrams, and the like represent various processes which may be substantially represented in computer readable medium and so executed by a computer or processor, whether or not such computer or processor is explicitly shown.

DETAILED DESCRIPTION OF THE INVENTION:
The foregoing descriptions of specific embodiments of the present disclosure have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiment was chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated.
The terms “a” and “an” herein do not denote a limitation of quantity but rather denote the presence of at least one of the referenced item.
The terms “having”, “comprising”, “including”, and variations thereof signify the presence of a component.
A motor control system is one of key components in any electromechanical systems. Control of the BLDC motor involves electronic commutation and closed loops. As discussed, three types of commutation approaches are typically used for controlling the speed of the motor, namely trapezoidal commutation, sinusoidal commutation and FOC.
Trapezoidal commutation is most widely used for controlling BLDC motor. This approach uses three current controllers for controlling current in stator windings. These current controllers cause torque ripples which are dominant during lower speeds. Such undesired torque ripple causes motor to vibrate and generate more noise which affects the smooth operation and precision finally resulting in reduction of lifespan of the motors.
The sinusoidal commutation does not cause torque ripple when BLDC motor operates at lower speeds, but this approach generates torque ripple at higher speeds and hence is not suitable for operation at higher speeds.
FOC, also known as vector control, is a technique, which provides better control capability over full torque and speed ranges. This approach is efficient in controlling output torque of the motor at both lower and higher speeds. In this approach, magnetic fields of stator and rotor are orthogonal to achieve maximum torque. This approach uses decoupled control of flux and torque and helps the BLDC motor to rotate above nominal speed using field weaking technique. This approach is used in applications wherever precise control of position is essential. FOC approach uses complex algorithms, multiple current controllers and transforms due to this, FOC requires controller with more processing capability, high-cost controllers.
In an embodiment of the present disclosure, a unified microcontroller based multi-motor control system and method thereof is disclosed. Referring to figure 1, the system comprises of a master control unit [101], communication unit [102], reference data extraction unit [103] and multiple motor control units. The Communication Unit [102] reads the commanded speed data from the Master control unit [101] and forwards the same to the motor control unit-1[104] and motor control unit-2 [105] based on the identifier data.
In an aspect, the present invention provides a unified microcontroller based multi-motor control system comprising:
a) a master control unit (101) is configured to set a target speed of a motor;
b) a communication unit (102) communicable connected to the master control unit (101) receives the set speed of the motor;
c) a reference data extraction unit (103) receives the set speed of the motor is configured to convert into a reference data; and
d) plurality of motor control units (104, 105), where each motor control unit comprises of following units a position sensing unit (207), a speed estimation unit (205), an inverter (209), a current sensing unit (206), a speed control unit (201), a current transformation unit (204), a current control unit (202), a pulse width modulation (PWM) generation unit (203) and a fault monitoring unit (211);
wherein the speed control unit (201) is configured to calculate a reference quadrature axis current based on the target speed and an actual speed of the motor, where the actual speed is calculated from ta rotor position data given by a position feedback sensors coupled on to the motors.
In an embodiment, each motor control unit includes a cascaded control loop comprising a speed control as an outer loop and a torque control as inner loop.
In an embodiment, position sensing unit (207) identifies the sector of electric motor to which the rotor is pointing.
In an embodiment, the inverter (209) circuit converts direct current to an alternating current and comprises plurality of switches which regulate the alternating current supplied to the stator windings.
In an embodiment, the current sensing unit (206) measures the alternating current drawn by the coil windings when the rotor is pointed to the particular sector.
In an embodiment, the current transformation unit (204) takes input from the current sensing unit (206) and estimates quadrature axis current of the rotor.
In an embodiment, the current control unit (202) takes actual quadrature axis current input from the current transformation unit (204) and target quadrature axis current from the speed control unit [201] and estimates the duty cycle required to achieve target speed.
In an embodiment, the PWM generation unit (203) generates the modulated signals based on the estimated duty cycle to drive the inverter switches (like MOSFET, IGBT etc.) to incrementally vary the speed of the rotor to achieve target speed, where each speed control unit (201) and current control unit (202) have an individual proportional-integral (PI) controller.
In an embodiment, the fault monitoring unit (211) raises the alarm if any faulty condition is detected and switches off the supply to the inverter (209) during execution of a motor control and communicates the fault status to the master control unit (101).
In an aspect, the present invention provides a unified microcontroller based multi-motor control method comprising steps of:
a) receiving reference (target speed) data from the master control unit;
b) extracting the data and forwarding it to both motor control unit based on identifier;
c) identifying the sector in which rotor is positioned and alignment using feedback sensor input;
d) estimating speed error between target and actual speeds;
e) calculating the target quadrature axis current based on the speed error;
f) sensing and measuring the alternate current supplied from the inverter to the stator;
g) transforming the measured current to direct axis current and quadrature axis current;
h) calculating error between target and measured quadrature axis currents;
i) estimating the duty cycle of the PWM signal and generating PWM signal; and
j) measuring the actual speed from feedback sensors and incrementally varying it based on proportional-integral gain values till it reaches target speed.
Further, referring to figure 2, each motor control unit comprises the following units:
1. Position sensing Unit [207]
2. Speed estimation Unit [205]
3. Inverter [209]
4. Current Sensing unit [206]
5. Speed control Unit [201]
6. Current Transformation Unit [204]
7. Current control Unit [202]
8. Pulse width modulation (PWM) Generation Unit [203]
9. Fault monitoring unit [211]
Position sensing unit [207] identifies the particular sector of electric motor to which rotor is pointing. Electric motor may comprise of one or more position sensors like Encoder, Hall Sensor and Resolver that identify the particular sector of electric motor to which rotor is pointing.
Power source supplies DC current for rotation of the rotor. An Inverter [209] circuit which converts direct current to alternating current and it [209] comprises of multiple switches which regulate the alternating current supplied to the stator windings. Current Sensing unit [206] measures the alternating current drawn by the coil windings when the rotor is pointed to the particular sector. Speed control Unit [201] estimates reference quadrature axis current based on target speed and actual speed of the motor. Actual speed is calculated from the rotor position data given by position feedback sensors coupled on to the motors.
Current Transformation Unit [204] takes input from the current Sensing unit [206] and estimates quadrature axis current of the rotor. A Current control Unit [202] takes actual quadrature axis current input from the current Transformation Unit [204]and target quadrature axis current from the Speed control Unit [201] and estimates the duty cycle required to achieve target speed. PWM Generation Unit [203] generates the modulated signals based on the estimated duty cycle to drive the inverter switches (like MOSFET, IGBT etc.) to incrementally vary the speed of the rotor to achieve target speed. Each Speed control Unit [201] and Current control Unit [202] have individual proportional-integral (PI) controller. Fault monitoring unit [211] raises the alarms for any faults and switches off the supply to the rotor during execution of the motor control algorithm.
Referring to figure 3, figure 3 illustrates a Motor control system Architecture in accordance with one aspect of the present disclosure. Further, Figure 4 illustrates the working principle (Flowchart) of motor control system in another aspect of the present disclosure.
In one embodiment, the position sensing unit [207] identifies the particular sector of electric motor to which rotor is pointing. An inverter [209] comprising of multiple switches converts direct current to alternating current for sourcing stator windings.
In one embodiment, the current sensing unit [206] measures the alternating current drawn by the coil windings and the current transformation unit [204] takes input from the current Sensing unit [206] and estimates quadrature axis current of the rotor.
In another embodiment, the current control unit [202] takes actual quadrature axis current input from the current Transformation Unit [204]and target quadrature axis current from the speed control Unit [201] and estimates the duty cycle of the pulse width modulation signals and the speed control unit [201] comprises of single speed proportional-integral controller for regulating speed of the motor.
Further, the current control unit [202] comprises of single current proportional-integral controller for regulating torque of the motor and an Inter-processor communication unit [309] shares the data with motor control units through internal communication bus. The Communication Unit [102] reads the target speed data from the master control unit [101] and forwards the same to both motor control units 1 [104] and 2 [105] based on the identifier data.
Yet in another embodiment, the speed control unit [201] estimates error between target speed and actual speed provided by the position feedback sensors and corrects the same and estimates the reference quadrature axis current based on the target speed, actual speed and the PI gain values.
Also, the fault monitoring unit [211] raises the alarm if any faulty condition is detected and switches off the supply to the inverter [209] during execution of the motor control algorithm and communicates the fault status to the master control unit [101].
The advantageous aspect of the present invention includes:
1. Model based motor control approach.
2. Multiple BLDC Motor control system based on FOC architecture and unified microcontroller.
3. Fault monitoring, correction and status feedback communication to master control unit [101].
4. Implementation of multiple motor control units in one motor control system. Each motor control unit includes cascaded control loop comprising speed control as outer loop and torque control as inner loop.
,CLAIMS:We Claim:

1. A unified microcontroller based multi-motor control system comprising:
a) a master control unit (101) is configured to set a target speed of a motor;
b) a communication unit (102) communicable connected to the master control unit (101) receives the set speed of the motor;
c) a reference data extraction unit (103) receives the set speed of the motor is configured to convert into a reference data; and
d) plurality of motor control units (104, 105), where each motor control unit comprises of following units a position sensing unit (207), a speed estimation unit (205), an inverter (209), a current sensing unit (206), a speed control unit (201), a current transformation unit (204), a current control unit (202), a pulse width modulation (PWM) generation unit (203) and a fault monitoring unit (211);
wherein the speed control unit (201) is configured to calculate a reference quadrature axis current based on the target speed and an actual speed of the motor, where the actual speed is calculated from ta rotor position data given by a position feedback sensors coupled on to the motors.
2. The unified microcontroller based multi-motor control system as claimed in claim 1, wherein each motor control unit includes a cascaded control loop comprising a speed control as outer loop and a torque control as inner loop.
3. The unified microcontroller based multi-motor control system as claimed in claim 1, wherein the position sensing unit (207) identifies the sector of electric motor to which the rotor is pointing.
4. The unified microcontroller based multi-motor control system as claimed in claim 1, wherein the inverter (209) circuit converts direct current to an alternating current and comprises plurality of switches which regulate the alternating current supplied to the stator windings.
5. The unified microcontroller based multi-motor control system as claimed in claim 1, wherein the current sensing unit (206) measures the alternating current drawn by the coil windings when the rotor is pointed to the particular sector.
6. The unified microcontroller based multi-motor control system as claimed in claim 1, wherein the current transformation unit (204) takes input from the current sensing unit (206) and estimates quadrature axis current of the rotor.
7. The unified microcontroller based multi-motor control system as claimed in claim 1, wherein the current control unit (202) takes actual quadrature axis current input from the current transformation unit (204) and target quadrature axis current from the speed control unit [201] and estimates the duty cycle required to achieve target speed.
8. The unified microcontroller based multi-motor control system as claimed in claim 1, wherein the PWM generation unit (203) generates the modulated signals based on the estimated duty cycle to drive the inverter switches (like MOSFET, IGBT etc.) to incrementally vary the speed of the rotor to achieve target speed, where each speed control unit (201) and current control unit (202) have an individual proportional-integral (PI) controller.
9. The unified microcontroller based multi-motor control system as claimed in claim 1, wherein the fault monitoring unit (211) raises the alarm if any faulty condition is detected and switches off the supply to the inverter (209) during execution of a motor control and communicates the fault status to the master control unit (101).
10. A unified microcontroller based multi-motor control method, the method comprising steps of:
a) receiving reference (target speed) data from the master control unit;
b) extracting the data and forwarding it to both motor control unit based on identifier;
c) identifying the sector in which rotor is positioned and alignment using feedback sensor input;
d) estimating speed error between target and actual speeds;
e) calculating the target quadrature axis current based on the speed error;
f) sensing and measuring the alternate current supplied from the inverter to the stator;
g) transforming the measured current to direct axis current and quadrature axis current;
h) calculating error between target and measured quadrature axis currents;
i) estimating the duty cycle of the PWM signal and generating PWM signal; and
j) measuring the actual speed from feedback sensors and incrementally varying it based on proportional-integral gain values till it reaches target speed.