Filtering a Switched Power Supply

Power Filter

As seen in the previous post, a simple switch or diode rectified output is still not a clean DC signal. The waveform contains AC components on top of the DC offset. The simplest methods for smoothing this output involve filtering through the use of passive storage elements such as capacitors or inductors. In essence, these components tend to smooth the […]

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The Effect of Phase on Switching Rectifiers

Three-phase power rectification diagram.

In the previous post, we examined some of the most basic switch based rectifying circuits and saw that the switch could be replaced with a passive diode. Here, we will explore what happens when the switch is no longer in phase with the input. Let us consider a different way to operate the switch. Using the same circuit as the […]

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Basic Power Conversion Examples

Large Inductor

Let’s look at a few examples of power electronic systems. Consider the circuit shown below. It contains an AC source, a switch, and a resistive load. It is therefore a simple but complete power electronic system. Just to get an idea of how power conversion might take place, let us assign some kind of control to the switch. What if […]

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Important Variables and Notation

Oscilloscope Sine Eave

In a power electronic system, several electrical quantities are of special interest. Efficiency has already been identified in previous posts. Maximum values of currents and voltages will be needed to determine the necessary device ratings. Energy flow is the underlying objective, and power and energy levels in each part of the system are very important. We are most interested in […]

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The Reliability Objective and Integration

DSP Chip

It is well established in military electronics that the more parts are in a system, the more likely it is to fail. As we shall see, power electronic circuits tend to have few parts, especially in the main energy flow paths. The necessary operations must be carried out through shrewd use of those parts. Often, this means that sophisticated control […]

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The Efficiency Objective and the Switch

On-Off Switch

As simple a circuit element as the light switch like the one illustrated below gives a reminder that the extreme requirements in power electronics are not especially novel. Ideally, when a switch is on, it provides vswitch = 0, and will carry any current imposed on it. When a switch is off, it blocks the flow of current (iswitch = […]

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The Basic Objectives of Electrical Conversion

Dart Board

The function of a power conversion circuit is to control the energy flow between a given electrical source and a given load. A converter must manipulate flow, but should not consume energy. The reason is simple. Since a power converter appears between a source and a load, any energy used within the converter is lost to the overall system. To be […]

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