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The DC Drive

6 Basic Adjustments. Speed ReferenceMinimum SpeedMaximum Speed AccelerationDecelerationCurrent Limit. Typical DC Drive Adjustments. . Adjustments - Speed Reference. Speed ReferenceTypically it is a potentiometer that an operator turns to adjust the speed of the machine.. Adjustments

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The DC Drive

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    1. The DC Drive In the beginning

    2. 6 Basic Adjustments Speed Reference Minimum Speed Maximum Speed Acceleration Deceleration Current Limit

    3. Typical DC Drive Adjustments

    4. Adjustments - Speed Reference Speed Reference Typically it is a potentiometer that an operator turns to adjust the speed of the machine.

    5. Adjustments – Min. Speed Minimum Speed How fast the machine will operate with the Speed Reference turned all the way DOWN.

    6. Adjustments – Max. Speed Maximum Speed How fast the machine will operate with the Speed Reference turned all the way UP.

    7. Adjustments - Acceleration Acceleration Rate How much time it will take to go from stop to full speed.

    8. Adjustments - Deceleration Deceleration Rate How much time it will take to go from full speed to stop.

    9. Adjustments - Current Limit Current Limit This limits the amount of current coming out of the drive. It’s based on the motors Full Load Amps.

    10. Basic DC Drive Operations Speed Reference - How fast you want the machine to go. Can be analog 0 - 10vdc or 4 - 20mA signal from a controller. Can also be a adjustment via parameter, network data or keypad input Signal is modified by Min. and Max. Speed Adjustments Goes to the Ramp Circuits

    11. Basic DC Drives Operations Ramp (Rate) circuits get the speed reference and ramps the signal up over a period of time. The time periods are adjustable via a pot, parameter or network data. Output goes to a summing junction.

    12. Basic DC Drive Operations

    13. Basic DC Drive Operations Summing Junction Takes the signal from the Ramp circuits and adds them together with some sort of feedback. Feedbacks can be speed,voltage or current. The result out of the summing junction is an error signal indicating the difference between the speed reference and the feedback. Another way to look at it is “ difference between how fast I want it to go verses how fast it is actually going” Output goes to the Major Loop (Speed or Voltage Loop)

    14. Basic DC Drive Operations

    15. Basic DC Drive Operations Major Loop Operational Amplifier (Loop 2) The speed error signal from the summing junction is the input. This amplifies the error signal. There is a feedback loop around the amplifier. This loop has a resister and capacitor (digital drive’s would be integrator and proportional response) Tuning these values of the feedback loop will affect the overall response (stability) of the drive.

    16. Basics DC Drive Operations

    17. Basic DC Drive Operations Stability

    18. Basic DC Drive Operations Second Summing Junction The input to this junction is the amplified error signal out of the Major Loop (Loop 2) operational amplifier. The signal is now called Current Reference. Current Reference is “Summed” together with the current feedback signal. The output signal goes to the Current Minor Loop (Loop 1) Operational Amplifier.

    19. Basic DC Drive Operations

    20. Basic DC Drive Operations Current Minor Loop (Loop 1) The current error signal from the summing junction is the input. This amplifies the error signal. There is a feedback loop around the amplifier which is a resistor and capacitor. (Digital drive’s is Integrator & Proportional response) Tuning these values will affect overall response (stability) of the drive.

    21. Basic DC Drive Operations

    22. Basic DC Drives Operations Gate Pulse Driver Circuits These circuits provide the pulse to the gate inputs on all the SCR’s. Input from CML. Everything in the drive up to this point is there to tell these circuits when to fire.

    23. Gate Pulse Timing

    24. Basic DC Drive Operations

    25. Basic DC Drive Operations Power Module This is where the SCR’s live. The Power Module has AC power connected to it which is what gets switched (through the SCR’s) to the motor armature circuit as DC.

    26. Basic DC Drive Operations

    27. SCR Construction

    28. Typical DC Drive - SCR’s

    29. Power Module (SCR’s) Non-Regen

    30. Power Module (SCR’s) Regen

    31. Basic DC Drive Operations Motor The interaction of 2 magnetic fields causes rotation (armature & field). Typically the Field coils have a constant voltage applied and we vary the voltage in the armature to get variable speed (up to Base speed) To go above base speed we have constant maximum voltage in the armature and then we weaken the field voltage.

    32. Speed Regulator

    33. Voltage Regulator

    34. Current Regulator

    35. Position Regulator

    36. Force Transducer Tension Regulator Basic

    37. Contactor Reversing

    38. 3 Basic Types of Braking Coast to Rest Dynamic Braking Regenerative Braking

    39. Braking Methods Coast to Rest The application coasts to a stop. Time to rest is determined by Friction, Windage and Inertia of the load. Dynamic Braking Inertia contained in a load causes the load to continue rotating generating a voltage and current in the armature circuit opposite in direction of motoring and being dropped across a high wattage resistor.

    40. Braking Methods Regeneration Inertia contained in a load causes the load to continue rotating generating a voltage and current in the armature circuit opposite in direction of motoring current. Using a second set of SCR’s connected opposite than the first set, these are fired so that current flow is allowed to flow in the opposite direction back to the AC line supply.

    41. 4 Quadrant Operations

    42. DC Dynamic Braking

    43. Braking Force

    44. Stopping Methods Compared

    45. The AC drive Then there was AC

    46. AC Drive Power Section

    47. Drive Basics - PWM AC Operation

    48. NEMA Enclosures For Drives

    49. NEMA Enclosures For Drives

    50. NEMA Enclosures For Drives

    51. NEMA Enclosures For Drives

    52. NEMA Enclosures For Drives

    53. NEMA Enclosures For Drives

    54. NEMA Enclosures For Drives

    56. Open Loop AC The “LEM” current sensors provide the current information to the microprocessor which is used in the vector calculation. As part of the vector calculation there is feedback form the encoder which is directly connected to the motor. The encoder provides the microprocessor with shaft position. The diagram shows Closed loop control. The “LEM” current sensors provide the current information to the microprocessor which is used in the vector calculation. As part of the vector calculation there is feedback form the encoder which is directly connected to the motor. The encoder provides the microprocessor with shaft position. The diagram shows Closed loop control.

    57. Closed Loop AC Vector The “LEM” current sensors provide the current information to the microprocessor which is used in the vector calculation. As part of the vector calculation there is feedback form the encoder which is directly connected to the motor. The encoder provides the microprocessor with shaft position. The diagram shows Closed loop control. The “LEM” current sensors provide the current information to the microprocessor which is used in the vector calculation. As part of the vector calculation there is feedback form the encoder which is directly connected to the motor. The encoder provides the microprocessor with shaft position. The diagram shows Closed loop control.

    58. Open Loop SensorLess In sensorless control we have the same current information but we are estimating the rotor position for the vector calculation We still have the same PWM design for all three drives(straight PWM, Flux vector, and Sensorless vectorIn sensorless control we have the same current information but we are estimating the rotor position for the vector calculation We still have the same PWM design for all three drives(straight PWM, Flux vector, and Sensorless vector

    59. 3 Components of Vector Control There are 3 components to vector control 1. Torque current which is the rotor current 2. Magnetising current which is established during self tuning and is the magnetizing current of the motor. 3. Motor current which is the vectored sum of the other two componentsThere are 3 components to vector control 1. Torque current which is the rotor current 2. Magnetising current which is established during self tuning and is the magnetizing current of the motor. 3. Motor current which is the vectored sum of the other two components

    60. Optimizing Torque output

    61. Magnetizing Current

    62. Torque Current

    63. Motor Current

    64. General Purpose Mode V/Hz

    65. Vector Mode Torque Curve

    66. Constant Torque Load

    67. Variable Torque Loads

    68. AC Snubber Braking

    69. AC Regeneration

    70. Transportation Application Matrix

    71. Metals Application Matrix

    73. Paper Application Matrix

    75. Consumer Application Matrix

    77. Gas/Oil/Mining Application Matrix

    79. THE END

    80. Notes

    81. Notes

    82. Notes

    83. Notes

    84. Notes

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