Development of a sensorless current control technique for high frequency link converters.
Avionics
High frequency link bidirectional converters are characterized by a high frequency inductor current. Superior dynamic performance and saturation prevention requires sensing of this high frequency current and high bandwidth ADCs for subsequent signal processing. Typically Hall effect based sensors, having their own reasonable footprints and volume, are directly mounted on the power bus bar. This makes the realization of a highly compact bus bar structure more difficult. A sensorless current envelope tracking based scheme has been proposed which also do not require any high bandwidth ADCs. The ingenuity of the proposed scheme lies in estimating the envelope of the fundamental component of the current and subsequently controlling it. This scheme also leads to direct estimation of the peak current envelope, which can be easily integrated with the overall control scheme for overcurrent protection and saturation prevention. Hence, a control scheme is arrived at which is equally effective as erstwhile techniques and at the same time comes with much lesser computational overhead. The proposed control scheme is validated through a laboratory prototype. One of the key experimental results are shown in Figure 1.
Fig. 1. Experimental results for peak envelope estimation. Top trace: estimated ipke envelope (1 V/div). Second trace: actual iLs (10 A/div) (a and b), (5 A/div) (c). Third trace: vo (50 V/div). Bottom trace of (a) and (b): io (2 A/div). Bottom trace of (c): vdc (50 /div). (a) and (b) Time 20 ms/div. (c) Time 1 s/div. (a) 50% step increase in load current. (b) 50% step decrease in load current. (c) 15% ramp variation in input voltage.
Ref: G. Nayak and A. Dasgupta, "Inductor Current Envelope Tracking-Based Sensorless Control of Dual Active Bridge Converter," in IEEE Transactions on Power Electronics, vol. 37, no. 7, pp. 7907-7915, July 2022, doi: 10.1109/TPEL.2022.3151503.
