In this program, if returns are saturated, the essential difference between the brand new operator efficiency as well as the actual production are provided to new type in of your own integrator having a gain regarding K a to allow brand new built-up value of this new integrator might be remaining at an actual worthy of. The brand new acquire regarding an enthusiastic anti-windup control is sometimes selected because the K an excellent = 1 / K p to avoid the fresh new personality of the limited current.
Fig. 2.37 suggests the newest experience of integrator windup having a good PI most recent operator, which is generated by a big improvement in the latest site value. Fig. 2.37A suggests the fresh abilities out-of a recent operator instead of an anti-windup control. Due to its soaked output voltage, the actual most recent displays a massive overshoot and you will an extended setting time. In addition, Fig. dos.37B reveals a current operator with an enthusiastic anti-windup manage. When the yields is saturated, the accumulated value of the fresh new integrator should be remaining at the a good best worth, leading to a significantly better show.
2.6.2.step 1 Increases options process of the proportional–integrated current operator
Select the control bandwidth ? c c of one’s most recent operator to-be inside step 1/10–1/20 of the altering regularity f s w and you can less than 1/twenty-five of the sampling volume.
The fresh new procedures step 1 and you may dos try interchangeable with each other, we.age., the brand new changing frequency might be dependent on the mandatory data transfer ? c c for current-control.
twelve.dos.dos Secure region of unmarried-loop DC-hook current control
According to the Nyquist stability criterion, a system can be stabilized by tuning the proportional gain under the condition, i.e., the magnitude is not above 0 dB at the frequency where the phase of the open-loop gain is (-1-2k)? (k = 0, 1, 2.?) [ 19 ]. Four sets of LC-filter parameter values from Table 12.1 , as listed in Table 12.2 , are thus used to investigate the stability of the single-loop DC-link current control https://datingranking.net/de/swinger-sites-de/. Fig. 12.4 shows the Bode plots of the open-loop gain of the single-loop DC-link current control Go, which can be expressed as
Figure 12.4 . Bode plots of the open-loop gain Go of the single-loop DC-link current control (kpdc = 0.01) corresponding to Table II. (A) Overall view. (B) Zoom-in view, 1000–1900 Hz. (C) Zoom-in view, 2000–3500 Hz.
where Gdel is the time delay, i.e., G d e l = e ? 1.5 T s and Gc is the DC-link current PI controller, i.e., Gc = kpdc + kidc/s. The proportional gain kpdc of the PI controller is set to 0.01 and the integrator is ignored since it will not affect the frequency responses around ?c1 and ?c2. It can be seen that the CSC system is stable in Cases II, III, and IV. However, it turns out to be unstable in Case I, because the phase crosses ?540 and ?900 degrees at ?c1 and ?c2, respectively.
To further verify the relationship between the LC-filter parameters and the stability, root loci in the z-domain with varying kpdc under the four sets of the LC-filter parameters are shown in Fig. 12.5 . It can be seen that the stable region of kpdc becomes narrow from Case IV to Case II. When using the LC-filter parameters as Cases I, i.e., L = 0.5 mH and C = 5 ?F, the root locus is always outside the unity circle, which indicates that the system is always unstable. Thus, the single-loop DC-link current control can be stabilized with low resonance frequency LC filter, while showing instability by using high resonance frequency LC filter. The in-depth reason is that the phase lag coming from the time delay effect becomes larger at the resonances from low frequencies to high frequencies, which affect the stability of the single-loop DC-link current control.
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