Contents
What is sub harmonic oscillation?
Sub-harmonic oscillation is normally characterized by observing alternating wide and narrow pulses at the switch node. For peak current mode control, sub-harmonic oscillation occurs with a duty cycle greater than 50%.
What causes subharmonic oscillation?
The source of subharmonic oscillations is the simultaneous conditions of fixed frequency and fixed peak amplitude of inductor current as shown in part a of the accompanying figure. Current increases at a rate (S1) equal to input voltage divided by inductor value.
What is subharmonic frequency?
Subharmonic are interharmonics with frequencies lower than fundamental frequency (60 or 50 Hz) [1]. The direct consequence of the low frequency current injection is low frequency voltage distortion which appears as fundamental component modulation.
What is subharmonic generation?
A subharmonic synthesizer is a device or system that generates subharmonics of an input signal. The nth subharmonic of a signal of fundamental frequency F is a signal with frequency F/n. Various harmonics can be amplified or modulated, although it is most common to boost the fundamental frequency’s lower octave.
Why is the power supply in current-mode instead of voltage mode?
In these applications, the power supply runs in voltage mode, maintaining a constant output voltage while providing the required current to the load. When the supply runs in current mode, the supply provides a constant current into a variety of load voltage conditions including a short circuit.
What is the difference between harmonics and Interharmonics?
While interharmonic and harmonic definitions are similar, their difference — that harmonics are periodic at the fundamental frequency and interharmonics are not — is important.
Do undertones exist?
In music, the undertone series or subharmonic series is a sequence of notes that results from inverting the intervals of the overtone series. While overtones naturally occur with the physical production of music on instruments, undertones must be produced in unusual ways.
How do you sing subharmonic?
Slide the tone up and then down to the lowest note you can sing. Slide the note slightly a half-note up and then bring your singing voice all the way down to the lowest note you can comfortably sing. Sustain the lowest note you can without your voice cracking or popping.
When does subharmonic oscillation occur in current mode?
You can find a good explanation of all this in this paper from TI: Basically subharmonic oscillation is not a small signal instability, it’s a large signal phenomenon in peak current mode control that occurs when the duty cycle is greater than 50%.
What are the different types of SMPs circuits?
SMPS is the Switched Mode Power Supply circuit which is designed for obtaining the regulated DC output voltage from an unregulated DC or AC voltage. There are four main types of SMPS such as The AC to DC conversion part in the input section makes the difference between AC to DC converter and DC to DC converter.
What causes instability in a current mode switch?
The difference between the average inductor current and the dc value of the sampled inductor current can cause instability for certain operating conditions. This instability is known as sub-harmonic oscillation, which occurs when the inductor ripple current does not return to its initial value by the start of next switching cycle.
What causes sub harmonic oscillation in DC DC converter?
Sub-harmonic oscillations in current-mode-controlled converters are easily revealed through simple drawings as shown in akellyirl answer. However, it is less known that these oscillations find their origin in the inner current-loop instability affected by the presence of a right-half-plane zeros (RHPZ) pair.