MUEV Phase IIIBy: Kevin Jaris & Nathan Golick
IntroductionPetroleum is a finite resource.Demand for clean energy is driving the increase in the production of electric cars.Improvements in regenerative braking techniques will increase the range and efficiency of electric cars.
Regenerative BrakingCars generally dissipate kinetic energy via friction braking.Regenerative braking recovers a significant amount of the kinetic energy.Energy returned to battery.Increases range per charge.
Past Work Phase IDesign a prototype electric vehicle test platform for testing with the following specifications: Minimum round trip distance of 25 miles Maximum speed of 40 mph Operate within temperature range of -10F to 100FAcquire and display data from the motor and battery subsystemsOperate within a curb weight of 800 to 1800 lbs
Past Work Phase IIModeling Battery DC Motor Controller Vehicle Dynamics Loads A/C Lighting Heat Verify and Optimize Vehicle Model Perform data acquisition Adjust model until desired performance is achieved. Compare experimental and simulated outputs of subsystems
Original Project GoalsDesign and simulate power electronics Build power electronics Test power electronics in labConnect to DC motor/generator Create braking profile Model in SimulinkInvestigate variable speed drive
Functional DescriptionThe DC motor/generator produces a back EMF voltage during regenerative braking.Back EMF voltage is the input to the boost converter.The boost converter output is 43 volts.Output voltage charges batteries.
Performance SpecificationsGenerate a constant 43 volt output voltage while in regenerative braking modeBraking voltages range from about 5 to 35 volts.System designed for minimal project construction costs.
System Block Diagram
Drive Shaft Coupling
Current Limited Control
Boost Converter/Power Electronics
Field Current Control Electronics
Boost Converter Basics
Design ProcessCalculate the component values Design and simulate the boost converterBuild boost converterAnalyzed and compared the results Solve problems that arose
Boost Converter Schematic
Low Voltage Input Boost Converter SimulationVin
High Voltage Input Boost Converter Simulation
Additional CircuitrySafety shut off circuitGate driver circuitSnubber circuit
IssuesMOSFET temperaturePower supply current limit Wire gaugeIC chips highly vulnerable to static discharge Individual to series inductor switch
Input Current and Drain Voltage
SolutionsParallel MOSFETsParallel inductorsThermocouple to monitor temperatureFan and heat sinks for heat dissipation to keep case temperature under 90 CMoved to power labReplaced wire with 16 gaugeTesting and replacement of ICs
Accomplished GoalsDesigned and simulated boost converter/power electronicsBuilt power electronicsTested power electronics
Future WorkComplete duty cycle controllerAttach DC motor/generator Test with braking profileModel subsystem in SimulinkConnect regenerative braking system to the MUEV
Increases net efficiency
More electric vehicles are in production
How efienct today?Cars generally dissipate energy Design and simulate the power electronics in PowerSIMPower electronics will be built based on PSIM verification and connected to a voltage source to verify proper operation.Use a controlled voltage on the additional motor to simulate various braking profiles applied to the MUEV motor. We will be testing the regenerative braking power electronics design with a matched set of DC motor/generators in the power lab instead of using the MUEV motor.Investigate the possibility of using a variable speed drive to recover energy at lower speeds.
The DC motor will drive the generator which produces a back EMF voltage and current output.The back EMF voltage and output current are the inputs to the boost converter.The boost converter will keep a constant output voltage about 43 volts.20% above the 36 volt lead acid batteries onboard.The boosted output voltage will be used to recharge the three onboard 12 volt batteries.
Generate a constant 43 volt output voltage from the boost converter while in regenerative braking mode from about 10% to 100% motor speed.Expected regenerative braking voltages will range from about 5 to 35 volts.Regenerative braking system designed with minimal cost.
Using shotkey diode so do not need turn on snubbersCalculate the component values of the boost converter.Design and simulate the boost converter design in PSIM.System design utilized as many on hand components as possible. Build the boost converter, analyze and compare the results to the simulated resultsSolve problems that arose and analyze the circuitry to fix the problems.
Rs is the equivalent resistance of hysteriesis of ferromagnetic core
Higher frequency higher hysteresis
Eventually battery will be 36 v and resistance will be 30m OhmsParallel inductorsParallel MOSFETsSafety shut off circuitGate driver circuit
Solid state relay (purchase)
Wire thickness from 20G to 16GCurrent cut in halfRds ON is the same
Power dissapation is cut factor 4Future teams can complete duty cycle controllerAttach DC motor/generator to test with braking profileConnect regenerative braking system to MUEV