Deadbeat predictive current regulator features fast dynamic responses. However, it suffers from the steady state current tracking error in a practical system due to the plant uncertainties, particularly the inductances. Instead of using observer-based disturbance voltage feedforward methods, this paper proposes a new closed form method to directly compensate the current tracking errors with a simple feedforward term added to the voltage commands. Zero steady-state error is achieved with negligible computation compared to the observer-based methods. The new method is first derived to tackle the inductance mismatch in the surface mount permanent magnet synchronous motor (SMPMSM), then the system close loop transfer function is established to prove that the proposed method guarantees the zero steady-state error even with mismatches of the stator resistance and rotor flux linkage. Furthermore, based on the proposed compensation method, noise suppression schemes are added and designed to reduce high frequency noise sensitivities in practical systems. Finally, the proposed method is extended to the interior permanent magnet synchronous motor (IPMSM). IPMSM system simulation and 68.5 kW experimental results are provided to validate the proposed method.

This paper studies the high power density bidirectional dc-dc converter with interleaving, soft-switching, and near critical conduction mode (near-CRM) operation. Systematic design and control methods are proposed to enhance the effectiveness of passive currents balancing between multiple interleaved phases without using individual phase current feedbacks. This paper first analyzes the zero voltage turn-on operation, including the turn-off energy diversion by the added snubber capacitor and the turn-off resonance models. Second, the intrinsic inverse co-relation between the phase current deviation and the resulting effective duty cycles variation is quantitatively formulated and modeled as a closed-loop mechanism that balances the currents passively. Then, the design constraints of the system parameters including the snubber capacitance, dead time, and valley currents of the near-CRM mode are formulated to guarantee the effectiveness of counteracting the current unbalance. Finally, a variable switching frequency control is proposed to actively control the valley current and maintain the current balancing effectiveness throughout the operating range. An IGBT-based 20-kW three-phase interleaved prototype with the maximum efficiency of 99.1% is constructed to verify the proposed design and control methods.

Voltage balance of series capacitors is crucial for multilevel converters. In this paper, a new voltage self-balance mechanism based on zero-voltage switching (ZVS) for a three-level DC-DC converter is proposed. Firstly, the near-CRM (critical conduction mode) to realize ZVS and its resonance transition are analyzed in detail. Then, the resonance times at peak and valley currents are analytically expressed, and it is discovered that the additional duty cycles are induced by the ZVS resonant transitions between the switch parasitic capacitors and resonance inductor. Meanwhile, the unbalanced capacitor voltages alter the initial resonance conditions, so that the resulting additional duty cycles tend to counteract the unbalanced voltages. To further quantify the proposed voltage self-balance mechanism, not only the relationship between the effective duty cycle and the unbalanced voltages are formulated, but also the overall feedback mechanism of the passive voltage self-balance is modeled and illustrated. Finally, a three-level DC-DC converter prototype is constructed to experimentally verify the ZVS and voltage self-balance mechanism in the near-CRM mode.

The effectiveness of a battery management system (BMS) in lithium-ion batteries (LIBs) is significantly dependent on the accuracy of battery sensors. However, owing to the highly nonlinear nature of LIBs, detecting small uncertainties in sensor measurements, which can lead to high estimation errors, poses a remarkable challenge. Moreover, in conventional BMS, sensor uncertainty detection and state estimation are treated separately which greatly reduces its effectiveness. Hence, this article presents an integrated framework for fast bias detection and state estimation to ensure reliable and safe operations. First, extensive experimentation is performed to statistically analyze the effects of different sensor uncertainties on multiple chemistries of LIBs. Second, a fast bias detection algorithm is proposed to identify small sensor offsets effectively. Third, upon successful bias detection, a hybrid extended nonlinear observer is proposed for simultaneously estimating all states, in which bias is treated as an augmented state. Lastly, the observability of the proposed design is investigated across various practical scenarios. Validation results, using 58 Ah NMC and 25 Ah LiFePO4 LIB cells, underscore the potential of this integrated strategy to enhance the safety of LIBs in commercial applications.

The nonlinear characteristics of inductors, especially those with soft magnetic powder cores, are often perceived as undesirable and should be typically either avoided or mitigated. However, this letter presents an innovative method to take advantage of the nonlinear behavior of inductors in interleaved dc–dc converters. By analyzing the total current shape after interleaving, a novel single-sensor current balancing method is proposed, which is realized by using peak current sampling and exploiting the inductor's nonlinearity. The proposed method not only achieves low-cost current balancing with just one current sensor but also reduces the hardware volume and complexity of the converter. In addition, it also provides inspiration for various current balancing applications. Experimental validations for an interleaved dc–dc converter confirm the effectiveness of the proposed current balancing scheme.

When multiple virtual synchronous generators (VSG)s operate in parallel in an islanded microgrid, the sudden load power change could lead to significant transient circulating (and oscillating) power. In this paper, the transient circulating power is first analyzed with the two-VSGs small signal model. On this basis, the paper defines parameter design principles that theoretically eliminate all transient circulating power. Due to the line impedances uncertainty in practice, the ideal parameter design is not always available. Then, to suppress the remaining transient circulating power, an enhanced VSG (EVSG) control strategy is further proposed, by deriving and revising a two-VSGs transfer function from load disturbance to power angles difference. The proposed parameter design principles and the EVSG can be applied sequentially, so that the transient circulating power can be systematically suppressed without the side-effects as in existing methods. An experimental platform with 3 VSGs is established. The parameter design principles and the EVSG are thoroughly validated by experimental results. This is also the first time the 3-VSGs experimental results are reported, while all the existing literature has 2-VSGs data. It confirms that the two-VSGs analytical results can be extended to systems with more VSGs.