The remaining questions pertain to a bidirectional converter that interfaces a battery bank to a main...

    

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The remaining questions pertain to a bidirectional converter that interfaces a battery bank to a main power bus in an electric vehicle. A schematic of the converter and how it fits in the system is shown below. The converter switches are realized using current bidirectional switches, which will be discussed in Chapter 4 (in the next course); these allow both discharging and charging of the battery. Battery bank batt it L roo ezt Main power bus D₂ C + V m bus AC motor drive AC motor When the vehicle is accelerating, power is drawn out of the battery bank, and the converter boosts the battery voltage att to the dc bus voltage Vus. The inductor current it is positive under these conditions, and transistor Q₁ conducts during the first interval for 0 < t < DTg. Diode D₂ conducts during the second interval for DT $ < t < Tg. Transistor Q₂ and diode D₁ do not conduct for this case. When the vehicle is decelerating, the AC motor can act as a generator to supply power extracted from the kinetic energy of the moving vehicle. This causes a reversal of the currents of the system, and the converter extracts power out of the dc bus to charge the battery. The inductor current it is negative under these conditions. Transistor Q₂ or diode D₁ conduct, while transistor Q₁ and diode D₂ do not conduct for this case. The IGBT transistors can be modeled as a constant voltage source VT in series with a resistance RT. The diodes can be modeled as a constant voltage source Vd. The inductor has dc winding resistance RL. Derive a dc equivalent circuit model for this converter under the conditions that the vehicle is accelerating and the inductor current is positive. Manipulate your model into the form illustrated below: Vbatt Re IL +1 Ve 1:m Bidirectional DC-DC converter model Vbus AC motor drive The vehicle operates with the following conditions and parameter values: • Vbatt - 240 V Vbus = 500 V VT = 1 V RT = 1.6 milli ohms Vd = 1.2 V RL = 4 milli ohms Power input to AC motor drive from dc bus = 150 kW ● ● ● 1. Calculate the duty cycle and enter its numeric value below. 2. For the conditions of Question 1, calculate the converter efficiency and enter its numeric value below 3. For the conditions of Question 1, calculate the conduction loss of the IGBT and enter its numeric value (in watts) below. The remaining questions pertain to a bidirectional converter that interfaces a battery bank to a main power bus in an electric vehicle. A schematic of the converter and how it fits in the system is shown below. The converter switches are realized using current bidirectional switches, which will be discussed in Chapter 4 (in the next course); these allow both discharging and charging of the battery. Battery bank batt it L roo ezt Main power bus D₂ C + V m bus AC motor drive AC motor When the vehicle is accelerating, power is drawn out of the battery bank, and the converter boosts the battery voltage att to the dc bus voltage Vus. The inductor current it is positive under these conditions, and transistor Q₁ conducts during the first interval for 0 < t < DTg. Diode D₂ conducts during the second interval for DT $ < t < Tg. Transistor Q₂ and diode D₁ do not conduct for this case. When the vehicle is decelerating, the AC motor can act as a generator to supply power extracted from the kinetic energy of the moving vehicle. This causes a reversal of the currents of the system, and the converter extracts power out of the dc bus to charge the battery. The inductor current it is negative under these conditions. Transistor Q₂ or diode D₁ conduct, while transistor Q₁ and diode D₂ do not conduct for this case. The IGBT transistors can be modeled as a constant voltage source VT in series with a resistance RT. The diodes can be modeled as a constant voltage source Vd. The inductor has dc winding resistance RL. Derive a dc equivalent circuit model for this converter under the conditions that the vehicle is accelerating and the inductor current is positive. Manipulate your model into the form illustrated below: Vbatt Re IL +1 Ve 1:m Bidirectional DC-DC converter model Vbus AC motor drive The vehicle operates with the following conditions and parameter values: • Vbatt - 240 V Vbus = 500 V VT = 1 V RT = 1.6 milli ohms Vd = 1.2 V RL = 4 milli ohms Power input to AC motor drive from dc bus = 150 kW ● ● ● 1. Calculate the duty cycle and enter its numeric value below. 2. For the conditions of Question 1, calculate the converter efficiency and enter its numeric value below 3. For the conditions of Question 1, calculate the conduction loss of the IGBT and enter its numeric value (in watts) below.