Over the past week, we have been working on the circuitry required for the project. The main piece of circuitry is the Buck Boost Converter, which is a DC to DC converter used to integrate both a LiPo 4.5 V battery and a 128 mF super capacitor.
The main feature of this circuit besides the two power sources are the two transistors in black, which are located in the middle of the circuit. The boost converter is the transistor lower on the image. This transistor is triggered whenever we need to draw more power from the supercapacitor. The buck converter is the transistor on top, and is primarily used for regenerative braking. The basic idea behind regenerative braking is that when a vehicle is slowing down, there is lost kinetic energy that can be converted to electrical potential and used to charge the supercapacitor. Each of these transistors, in our final design, will be given a PWM signal to the gate pin so as to not only determine which transistor is on, but also how long it is on. The two buttons on the circuit were used to test basic charging and discharging of the supercapacitor.
The second circuit we have been working on this week is a simple amplifying circuit to convert the 3.3V PWM of the mBed microcontroller to 5V. This circuit is a simple amplification circuit using two op-amps.
Our next steps from here are to test the amplifier circuit using PWM signals from an mBed (we've only tested thus far using 3.3V VDD). More importantly, however, our goal is to write the control system using various inputs from the buck-boost converter circuit, as well as drive and load motor speeds, and determine which of the two transistors needs to be on, and for what duty cycle/period. Our goal is to finish writing the control system by Monday April 13th and to be able to run simple tests by April 16th. These simple tests should include being able to run both the load and drive motor, being able to test regenerative braking, and being able to boost the drive motor when there is a high load.
The main feature of this circuit besides the two power sources are the two transistors in black, which are located in the middle of the circuit. The boost converter is the transistor lower on the image. This transistor is triggered whenever we need to draw more power from the supercapacitor. The buck converter is the transistor on top, and is primarily used for regenerative braking. The basic idea behind regenerative braking is that when a vehicle is slowing down, there is lost kinetic energy that can be converted to electrical potential and used to charge the supercapacitor. Each of these transistors, in our final design, will be given a PWM signal to the gate pin so as to not only determine which transistor is on, but also how long it is on. The two buttons on the circuit were used to test basic charging and discharging of the supercapacitor.
The second circuit we have been working on this week is a simple amplifying circuit to convert the 3.3V PWM of the mBed microcontroller to 5V. This circuit is a simple amplification circuit using two op-amps.
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