TDFS Input Impedance of Step-Down (Buck) DC to DC Converter - Switching My GalinaDesigner21 × Galina Member for 10 years 4 months 104 designs 3 groups Member of the PartQuest Explore team. Title Description <p>This example demonstrates the use of the TDFS method (Time Domain Frequency Sweep) to measure the input impedance of a switching DC/DC power converter. The converter circuit is identical to the design shown in the companion example: “Step-Down (Buck) DC to DC Converter - Switching”.</p><p>In this example, the TDFS impedance measurement model applies a 12V DC bias to the line input, in addition to a sinusoidal stimulus with 3V peak amplitude, and a frequency range from 3 kHz to 30 kHz. The input current is measured and the impedance vs. frequency is computed. </p><p>The results show that the impedance magnitude (blue waveform) is approximately 5.0 Ohms at low frequency, This is approximately the reflected value of the 1 Ohm load resistor, multiplied by the effective DC/DC conversion ratio squared:</p><p> 1 Ohm * (12.0/5.0)**2 = 5.76 Ohm</p><p>The phase measurement (red waveform) shows -175 degrees at low frequency, indicating that this is effectively a "negative resistance". That is, the input current decreases when the line voltage increases. This behavior can be observed directly in the time domain waveforms, where the line voltage (brown waveform) and the input current (green waveform) are almost completely out of phase at 3 kHz. </p><p>This negative impedance, or constant power load characteristic, can be destabilizing in power distribution systems. This will be demonstrated in a related design, and in Part 3 of the TDFS Blog Series, coming soon!</p> About text formats Tags Buck ConverterOp-Amp Lead-Lag CompensatorSwitching ConverterPEG127KA3110Q Electrolytic CapacitorMC33272A OP-AMPXAL6060-223 InductorNRVTS560EMFS Schottky Power RectifierTDFSTDFS ImpedanceNegative ImpedanceConstant Power Loads Select a tag from the list or create your own.Drag to re-order taxonomy terms. License - None - What's this? Design Titleby Galina × Embed Design Copy Embed Code <iframe allowfullscreen="true" referrerpolicy="origin-when-cross-origin" frameborder="0" width="100%" height="720" scrolling="no" src="https://explore.partquest.com/embed-design/172716"></iframe> Embed Live Design Copy Embed Code <iframe allowfullscreen="true" referrerpolicy="origin-when-cross-origin" frameborder="0" width="100%" height="720" scrolling="no" src="https://explore.partquest.com/node/172716"></iframe> Share a Link Copy URL https://explore.partquest.com/node/172716 TDFS Input Impedance of Step-Down (Buck) DC to DC Converter - Switching Mike DonnellyDesigner19 × Mike Donnelly Member for 10 years 4 months 1,529 designs 10 groups Member of the PartQuest Explore Development Team. Focused on modeling and simulation of analog, mixed-signal and multi-discipline systems covering a broad range of applications, including power electronics, controls and mechatronic systems. Title Description <p>This example demonstrates the use of the TDFS method (Time Domain Frequency Sweep) to measure the input impedance of a switching DC/DC power converter. The converter circuit is identical to the design shown in the companion example: “Step-Down (Buck) DC to DC Converter - Switching”.</p><p>In this example, the TDFS impedance measurement model applies a 12V DC bias to the line input, in addition to a sinusoidal stimulus with 3V peak amplitude, and a frequency range from 3 kHz to 30 kHz. The input current is measured and the impedance vs. frequency is computed. </p><p>The results show that the impedance magnitude (blue waveform) is approximately 5.0 Ohms at low frequency, This is approximately the reflected value of the 1 Ohm load resistor, multiplied by the effective DC/DC conversion ratio squared:</p><p> 1 Ohm * (12.0/5.0)**2 = 5.76 Ohm</p><p>The phase measurement (red waveform) shows -175 degrees at low frequency, indicating that this is effectively a "negative resistance". That is, the input current decreases when the line voltage increases. This behavior can be observed directly in the time domain waveforms, where the line voltage (brown waveform) and the input current (green waveform) are almost completely out of phase at 3 kHz. </p><p>This negative impedance, or constant power load characteristic, can be destabilizing in power distribution systems. This will be demonstrated in a related design, and in Part 3 of the TDFS Blog Series, coming soon!</p> About text formats Tags Buck ConverterOp-Amp Lead-Lag CompensatorSwitching ConverterPEG127KA3110Q Electrolytic CapacitorMC33272A OP-AMPXAL6060-223 InductorNRVTS560EMFS Schottky Power RectifierTDFSTDFS ImpedanceNegative ImpedanceConstant Power Loads Select a tag from the list or create your own.Drag to re-order taxonomy terms. License - None - What's this? Design Titleby Mike Donnelly × Embed Design Copy Embed Code <iframe allowfullscreen="true" referrerpolicy="origin-when-cross-origin" frameborder="0" width="100%" height="720" scrolling="no" src="https://explore.partquest.com/embed-design/131701"></iframe> Embed Live Design Copy Embed Code <iframe allowfullscreen="true" referrerpolicy="origin-when-cross-origin" frameborder="0" width="100%" height="720" scrolling="no" src="https://explore.partquest.com/node/131701"></iframe> Share a Link Copy URL https://explore.partquest.com/node/131701
TDFS Input Impedance of Step-Down (Buck) DC to DC Converter - Switching Mike DonnellyDesigner19 × Mike Donnelly Member for 10 years 4 months 1,529 designs 10 groups Member of the PartQuest Explore Development Team. Focused on modeling and simulation of analog, mixed-signal and multi-discipline systems covering a broad range of applications, including power electronics, controls and mechatronic systems. Title Description <p>This example demonstrates the use of the TDFS method (Time Domain Frequency Sweep) to measure the input impedance of a switching DC/DC power converter. The converter circuit is identical to the design shown in the companion example: “Step-Down (Buck) DC to DC Converter - Switching”.</p><p>In this example, the TDFS impedance measurement model applies a 12V DC bias to the line input, in addition to a sinusoidal stimulus with 3V peak amplitude, and a frequency range from 3 kHz to 30 kHz. The input current is measured and the impedance vs. frequency is computed. </p><p>The results show that the impedance magnitude (blue waveform) is approximately 5.0 Ohms at low frequency, This is approximately the reflected value of the 1 Ohm load resistor, multiplied by the effective DC/DC conversion ratio squared:</p><p> 1 Ohm * (12.0/5.0)**2 = 5.76 Ohm</p><p>The phase measurement (red waveform) shows -175 degrees at low frequency, indicating that this is effectively a "negative resistance". That is, the input current decreases when the line voltage increases. This behavior can be observed directly in the time domain waveforms, where the line voltage (brown waveform) and the input current (green waveform) are almost completely out of phase at 3 kHz. </p><p>This negative impedance, or constant power load characteristic, can be destabilizing in power distribution systems. This will be demonstrated in a related design, and in Part 3 of the TDFS Blog Series, coming soon!</p> About text formats Tags Buck ConverterOp-Amp Lead-Lag CompensatorSwitching ConverterPEG127KA3110Q Electrolytic CapacitorMC33272A OP-AMPXAL6060-223 InductorNRVTS560EMFS Schottky Power RectifierTDFSTDFS ImpedanceNegative ImpedanceConstant Power Loads Select a tag from the list or create your own.Drag to re-order taxonomy terms. License - None - What's this? Design Titleby Mike Donnelly × Embed Design Copy Embed Code <iframe allowfullscreen="true" referrerpolicy="origin-when-cross-origin" frameborder="0" width="100%" height="720" scrolling="no" src="https://explore.partquest.com/embed-design/131701"></iframe> Embed Live Design Copy Embed Code <iframe allowfullscreen="true" referrerpolicy="origin-when-cross-origin" frameborder="0" width="100%" height="720" scrolling="no" src="https://explore.partquest.com/node/131701"></iframe> Share a Link Copy URL https://explore.partquest.com/node/131701