Negar Honarmand, Ali Motebaheri Nejad, Hamoun Hayati
supervised by Professor Bin Wu
The objective of the project is to design and implement a working prototype of a 1.5kW (AC Level 1) PHEV charger that can meet the SAE Standard J1772 developed by Society of Automotive Engineers. The rated input AC Voltage that is used is 120V/60Hz. The DC output range is 0 to 150 V. The rated output power is 1.5 KW. The rated efficiency should be more than 90%.Total Line Current THD should be less than 5%. The input power factor should be more than 0.98 which is almost unity. The charging profile is constant current charging. The maximum DC output voltage is 150 V and since the power is 1.5 KW, the output current should be 10 A. The interleaved boost converter and a diode rectifier were used in this project. The switching frequency that was used is 15 KHz. The voltage after the rectifier is half wave sinusoidal waveform which is positive. The interleaved boost converter consists of two parallel connected boost converter units, which are controlled by a phase-shifted switching function (interleaved operation). Since this converter has two parallel units, the duty cycle for each unit is equal to (Vout-Vin)/Vout, and it is same for each unit due to parallel configuration. A phase shift should be implemented between the timing signals of the first and the second switch. Since there are two units parallel in this converter, the phase shift value is 180 QUOTE . The PWM duty cycle signals are generated by comparing a level control signal (Vc) with a constant peak repetitive triangle signal (Vst). The frequency of the repetitive triangle signal establishes the switching frequency. Since the interleaved boost converter requires two PWM signals to drive both of switches, the additional work necessary to generate two of PWM signals from single duty cycle formula. The first PWM signal is produce when the control signal V1 is less than Vst and the second PWM signal is produce when the control signal V2 is greater than Vst. In addition, a PI controller was used for DC current feedback control to control the output current. Since the current in the output should be 10 A, the reference current that was used is 10 A. Furthermore, Power Factor Correction (PFC) is used to improve the input power factor, voltage regulation and Total Harmonic Distortion (THD) of the input current. Without such a PFC stage, the current drawn will have significant harmonic contents due to the discontinuous currents drawn over a short duration. As a result, it will cause in increased network losses, radiated emission and total harmonic distortion. At higher power levels, it can reduce overall efficiency of the system.
Project targeted applications: Battery Charger for Plug-in Electric Vehicle