Week-7 Challenge: DC Motor Control

1. A. Explain a MATLAB demo model named ‘Speed control of a DC motor using BJT H-bridge’.

    B. Comment on the armature current shoot-up from the scope results.

    C. Refer to the help section of ‘The Four-Quadrant Chopper DC Drive (DC7) block’. Compare it with the H-bridge model.

2. Develop a 2-quadrant chopper using simulink & explain the working of the same with the relevant results. (Refer to article - Multiquadrant operation of motor )

3. Explain in a brief about operation of BLDC motor.

       AIM :

        To create speed control of a DC mator using BJT H- bridge circuit and armature current shoot up and the four quadrant chopper DC Drive and 2 quadrant chopper using simuling ruselt and BLDC motor all the matlab simulation and result.

1. A. Explain a MATLAB demo model named ‘Speed control of a DC motor using BJT H-bridge’.

    B. Comment on the armature current shoot-up from the scope results.

    C. Refer to the help section of ‘The Four-Quadrant Chopper DC Drive (DC7) block’. Compare it with the H-bridge model.

         MATLAB demo named ‘Speed control of a DC motor using BJT H-bridge’ forward or backward circuit.

 H-bridge model of circuit is a 'A' side and 'b' side is used to the BJT bipolar junction transistors is using h-bridge DC motor drive circuit arrangement of transistor that allows a circuits full control over a standard electronics DC motor. H-bridge is allows a microcontroller, logic chip,or remote controle to electronically command the motor forward, reverse brake and coast. 

 H-bridge circuit :   

    H-bridge circuit is the Q1 and Q2 is bi bolar or fet transistor high voltage. this circuit is the diode is D1 and D4 is called catch diode and usually of a schottky type.                  

       Q1 side is the diode D1 and Q4 side D4 diode is motor loade is shorted the circute is supply voltage to load. this is forwade side.

      H-bridge circuit is the Q2 and Q3 is called diode will be aivate is the diode D2 and D3 is usede.

        H-bridge is the Dc motor to  voltage is Q1 and Q4 is Diode is the D1 and D2 is used. of IGBT blocking.

             MATLAB SINULINK OF DC MOTOR USING IGBT H-BRIDGE      

          The speed control of a DC motor using BJT H-bridge this example  shows the simulation of an H-bridge used to generate a choppeed voltage and to control the speed of a DC motor.

           the pulse generator of 500hz og the puls is used dc motor load is source voltage and bjt using igbt circuit connecting load torque proportional square of speed fan type (t=k*w^2).

      the bipolar junction transistor(BJT) when used for power switching applications operates as an IGBT. when it is conducting(BJT operating in the saturated region, forward voltage of vfis developed between collector and emitter in the range of 1 v. Therefore,the IGBT block can be used to model the BJT device.

   simulation

The motor starts in the positive direction with a duty cycle of 75% (mean DC voltage of 180V). At t= 0.5 sec., the armature voltage is suddenly reversed and the motor runs in the negative direction.

'Scope' shows motor speed, armature current and load torque and 'Currents' shows currents flowing in BJT Q3 and diode D3.

    currents of IGBT and diode simulation : 

        C. Refer to the help section of ‘The Four-Quadrant Chopper DC Drive (DC7) block’. Compare it with the H-bridge model.

         The 200 HP DC motor is separately excited with a constant 150 V DC field voltage source. The armature voltage is provided by an IGBT converter controlled by two PI regulators. The converter is fed by a 515 V DC bus obtained by rectification of a 380 V AC 50 Hz voltage source. In order to limit the DC bus voltage during dynamic braking mode, a braking chopper has been added between the diode rectifier and the DC7 block

   circuit of fourth qudrande of DC chopper :

           The four-quadrant DC drive block using these function of speed controller  DC and regulation switch, current controller DC, chopper. armature voltage, speed referance, motor torque referance are given as inputs. motor, converter, controller, motor angular speed are get as outputs.

      PI current controller PIspeed controller is used in the regulation switch of IGBT H-bridge circuit using chopper.

2. Develop a 2-quadrant chopper using simulink & explain the working of the same with the relevant results. (Refer to article - Multiquadrant operation of motor )

                the two quadrant chopper operation using simulink. in the it is obtained by connecting  type-A and type-B chopper in parallel. 

The circuit digram :

      CH = chopper switch

      D2 = diode

      FD = free-wheeling diode

The Two-Quadrant Chopper block represents a two-quadrant controlled chopper for converting a fixed DC input to a variable DC output. The block contains two switching devices.

GTO — Gate turn-off thyristor. For information about the I-V characteristic of the device, see GTO.

Ideal semiconductor switch — For the  information about the I-V characteristic of the device, see Ideal Semiconductor Switch of the BJT circuit.

IGBT — Insulated-gate bipolar transistor. For information about the I-V characteristic of the device, see IGBT (Ideal, Switching).

MOSFET — N-channel metal-oxide-semiconductor field-effect transistor. For information about the I-V characteristic of the device, see MOSFET (Ideal, Switching).

Thyristor — For information about the I-V characteristic of the device, see Thyristor (Piecewise Linear).

Averaged Switch — Semiconductor switch with an anti-parallel diode. The control signal port, G, accepts values in the [0,1] interval. When the value at port G is equal to 0 or 1, the averaged switch is either fully opened or fully closed, and it behaves similarly to the Ideal Semiconductor Switch block with an anti-parallel diode this diode is conect to BJT circuit and  1 to 2. When the value at port G is between 0 and 1, the averaged switch is partly opened. You can then average the PWM signal over a specified period. This allows for undersampling of the model or using modulation waveforms instead of PWM signals.

        3. Explain in a brief about operation of BLDC motor.

      The BLDC motor is works on the principle similar to theat of DC motor. the current carrying conductor placed in amagnetic experience a force.

    BLDC motor and application of such places as computer peripherals of the hand help power tools and vechile ranging from model. BLDC motor stands for Brushless direct current motor and as name magnets instead of electromagnets that are used in conventional motors. the permanent magnets of BLDC motor have less energy and heat losses compared to electromagnets.

    A BLDC motor is electronically commuted DC motor wich does not have brushes. the controller provides of current to motor windings which control the speed and torque of the synchronous motor.

   BLDC motor Advantages and Disadventages :

     1) this BLDC motor is compact in size and provide high torque with better speed control and efficency

      1) Some disadvandge like high cost, resonance issue, and complex wiring setup due to the involvement of electronic control.

   IMPORTANT :

    because computers control the electrical current brushless DC motors can achve much more precise motion control.

   A brushless DC motor consists of a rotor in form of a permanent magnet stator in form of polyphase 

armature windings. it differs from conventional DC motor  contains brushes and the commutation is done using electrically.

       OPEN AND CLOSED LOOP SPEED CONTROL :

   It is simply controlling the DC voltage applied to motor terminal by chopping the dc voltage

   It controlling the input supply voltage throgh the speed feed feeback from the motor. thus the supply voltage is controlled depending on the erroe signal.

    Application to Speed Control of Brushless DC Motor :

   to using the circuit and working all BLDC motor.

   CONCLUSION :

      To conclute matlab sinulation and all DC motor control H-bridge circuit and BLDC circuit using and 

four and two quadrant chopper using simuling module and various result.