Electric Motor for Challenge XMembersMotivationOverviewDesign ConstraintsConfigurationSlide 7TestingSlide 9Motor DesignSlide 11Slide 12Slide 13Controller DesignSlide 15Future WorkAcknowledgementsReferencesQuestions??Electric Motor Electric Motor for Challenge Xfor Challenge XMembersMembersFaculty AdvisorFaculty Advisor Dr. Marshall MolenDr. Marshall MolenTeam MembersTeam MembersMichael RobertsonMichael RobertsonCraig RossCraig RossDustin OttDustin Ott Jeff Smith Jeff Smith (Team leader)(Team leader)Hardware, testing, Website, simulation Hardware, testing, Hardware, Hardware, testing, Website, simulation Hardware, testing, Hardware, testing,testing, and research and research and research and researchand research and research and research and researchMotivationMotivationBecome involved in an effort to make Become involved in an effort to make vehicles cleaner and more efficientvehicles cleaner and more efficientGain experience in a large-scale Gain experience in a large-scale engineering effortengineering effortHelp MSU winHelp MSU winOverviewOverviewMany alternatives to a gasoline engine exist. In several lies a common thread:Electrical energy storage deviceElectrical energy storage deviceElectric motorElectric motorThe motor provides extra efficiency, high The motor provides extra efficiency, high starting torque, and the ability to starting torque, and the ability to recapture energy from the wheels.recapture energy from the wheels.Design ConstraintsDesign ConstraintsPowerPower90 – 110 hp90 – 110 hpMotor EfficiencyMotor Efficiency> 75%> 75%Generator Generator Must allow for for Must allow for for battery rechargingbattery rechargingStrengthStrengthMust handle high Must handle high starting torquestarting torqueSizeSizeMust fit in carMust fit in carWeightWeight< 800 lb< 800 lbConfigurationConfigurationOriginally, we considered 3 optionsOriginally, we considered 3 options1 AC induction motor1 AC induction motor2 AC induction motors2 AC induction motors1 AC induction + 1 DC permanent magnet motor1 AC induction + 1 DC permanent magnet motor1 AC induction motor seemed the best compromise 1 AC induction motor seemed the best compromise between performance and size / weightbetween performance and size / weightConfigurationConfigurationAnother option: 1 DC permanent magnet motorAnother option: 1 DC permanent magnet motorHigh energy densityHigh energy densityBetter speed controlBetter speed control> 90% efficient as both a motor and a generator> 90% efficient as both a motor and a generatorBrushed or brushless?Brushed or brushless?Brushless DC motors have longer lives, require less Brushless DC motors have longer lives, require less maintenance, and have better thermal / electrical / maintenance, and have better thermal / electrical / mechanical characteristicsmechanical characteristicsTestingTestingTo test the accuracy of the efficiency numbers, we To test the accuracy of the efficiency numbers, we decided to measure the characteristics of a smaller decided to measure the characteristics of a smaller brushless DC motor.brushless DC motor.Motor – Bosch Rexroth MKD-112C-058Motor – Bosch Rexroth MKD-112C-058Controller – Bosch Rexroth DKC01.3-100Controller – Bosch Rexroth DKC01.3-100Motor was operated via DriveTopMotor was operated via DriveTopMotoring characteristics were measured by placing Motoring characteristics were measured by placing various loads on the motorvarious loads on the motorTestingTestingResultsResultsMotoringMotoringMore testingMore testingneededneededGeneratingGeneratingWere not able to couple the MKD-112C with Were not able to couple the MKD-112C with another motor to test the generation another motor to test the generation capabilitiescapabilitiesTorque vs. Speed0123456781000 1200 1400 1600 1800 2000 2200 2400 2600 2800Spe e d (rpm )Torque (ft.lbs)Torque (ft.lbs)Motor DesignMotor DesignDimensionsDimensionsPower is proportional to l x rPower is proportional to l x r22 However, small r is essential for fitting under the However, small r is essential for fitting under the vehiclevehicleAlso, a long, thin motor would work better, Also, a long, thin motor would work better, mechanicallymechanicallyMotor DesignMotor DesignMaterialsMaterialsElectrically magnetized componentsElectrically magnetized componentsSimple field-weakening [1]Simple field-weakening [1]Permanent magnetPermanent magnetHigher torque, more compact [1]Higher torque, more compact [1]Magnetic compositesMagnetic compositesIncrease torque/weight ratio, decrease axial length [2]Increase torque/weight ratio, decrease axial length [2]Motor DesignMotor DesignFeedback [3]Feedback [3]Hall sensorsHall sensorsSimple controlSimple controlMore elaborate motorMore elaborate motorBack EMF sensingBack EMF sensingMore complex controlMore complex controlLess maintenanceLess maintenanceLess motor componentsLess motor componentsMotor DesignMotor DesignPossible modificationPossible modificationMultiple windings [4]Multiple windings [4]Two sets of windings with different numbers of Two sets of windings with different numbers of turns can act as an electric gear systemturns can act as an electric gear systemUseful for providingUseful for providing high starting torque high starting torque while retaining a while retaining a large region of large region of operation operationController DesignController DesignConcept [3]Concept [3]Two switchesTwo switches are closed at a are closed at a time timeThe rotor positionThe rotor position sensors are used to determine which two to activate sensors are used to determine which two to activatePulse widths determine the desired speed of thePulse widths determine the desired speed of the motor motorBack EMF zero-crossing can be translated to lookBack EMF zero-crossing can be translated to look like Hall sensor data like Hall sensor dataController DesignController DesignCommutation Algorithm [3]Commutation Algorithm [3] // If the state has not changed, do nothing// If the state has not changed, do nothing if (sensor_port = sensor_old) if (sensor_port = sensor_old) return return // Update the PWM outputs and retain the new state // Update the PWM outputs and retain the new state sensor_old sensor_old sensor_port
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