Power Supply

Power Supply¶

Input Filter
- Transformer
Rectifier
PFC
Power Stage
XFMR
Output Circuits

Input Filter¶

LC Low-pass filters:
- Rounds out the edges
- Made up of RLC circuit (Resistor, Capacitor and Inductor)

Use Transformer to Reduce the Voltage Input.

Use a varistor (voltage dependent resistor) to prevent high voltage spikes on the electrical power grid from damaging the power supply.

Rectification¶

Use diodes to direct Electron flow in one direction.
- Diodes have an intrinsic voltage drop across them which makes them less efficient
Electric Wave is a Absolute value Sin wave.
thyristors or MOSFETs can be used if the input is used to switch between wires
- These are more efficient but are harder to implement

Connect 4 diodes to have directed flow from both L and N to the new DC+ and the DC-

L input -----  >| -------- DC+
             \   /
              \ >|
               X
              / |<
             /   \
Neutral ----- |<  -------- DC-

Half Wave Rectifier¶

Only one of the outputs from Transformer has a diode to rectify that line in one direction.

Full Wave Rectifier¶

Both of the outputs from Transformer has a diode to rectify that line in one direction.

Bridge Rectifier¶

Both of the outputs from Transformer has a diode to rectify that line and also have two more diodes to redirect from the ground to the output.

Power Factor Correction (PFC)¶

Converts the High Voltage to High Frequency

Apparent power: The Load Voltage * The Load Current. This is the measured current and voltage on the system

True Power: This is the Wattage from a watt meter on the circuit.

Reactive Power: Is the sqrt of the difference of the the apparent power squared and the true power squared.

\[ \texttt{true\_power}^2 + \texttt{reactive\_power}^2 = \texttt{apparent\_power}^2 \\ \texttt{apparent\_power} = \sqrt{\texttt{true\_power}^2 + \texttt{reactive\_power}^2) \]

Reducing the Reactive power improves the efficiency of the power supply. A correct Capacitance needs to be calculated

\[ resistance = \dfrac{\texttt{ac\_voltage}^2}{\texttt{reactive\_power}} \\ capacitance = \dfrac{\texttt{1}} {2\pi * \texttt{ac\_frequency} * resistance} \]

This capacitance then reduces the reactive_power which makes the apparent_power about the same as the true_power.

\[ \texttt{true\_capacitance} = \dfrac{1}{2\pi* resistance * \texttt{ac\_frequency}} \\ \dfrac{resistance}{\texttt{ac\_voltage}^2} = \texttt{capacitance\_power} \\ \texttt{true\_power}^2 + (\texttt{reactive\_power}-\texttt{capacitance\_power})^2 = \texttt{apparent\_power}^2 \]

Since reactive_power will be almost equal to the capacitance_power this makes true_power almost equal to the apparent_power.

Active¶

Passive¶

Power Stage¶

Uses Pulse Modulated Width (PWM) to send the correct power (Wattage) depending on the load.
- PWM quickly switches the power on and off again

Output Rectifier¶

Uses a Transformer to convert the High frequency low voltage into a stable Output Voltage.

DC to DC Conversion¶

The magic of DC-DC voltage conversion