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Gallium nitride high electron mobility transistor (GaN HEMT) has fast switching speed and low threshold voltage, which could result in a severe false triggering voltage pulse at the synchronous freewheeling transistor in bridge-leg circuit when the control transistor turns on. To suppress the crosstalk phenomenon, this article proposes an analytical model about the crosstalk voltage, with consideration of nonlinearities in capacitance–voltage (C–V) of GaN HEMT. By utilizing the equivalent circuit of control transistor and synchronous freewheeling transistor, the number of analytical model parameters to be extracted can be reduced significantly. Besides, the nonlinear characteristic of junction capacitances is taken into account in the model, and the accuracy is verified by the current–voltage (I–V) curve of capacitances. Based on the model, an exhaustive investigation into the impact of device and circuit parameters on the crosstalk phenomenon is conducted. Further, for the purpose of evaluating the oscillation of crosstalk voltage, the damping ratio and oscillation frequency are acquired. The proposed model can be applied to guiding GaN device selection and printed circuit board (PCB) circuit design. The effectiveness and superiority of the proposed model are verified with simulations and experiments on a double pulse test platform. [ABSTRACT FROM AUTHOR]

Beat phenomenon is an important concern in the reduced dc-link capacitance motor drive system. In previous research works, the topic is mainly concentrated on the beat phenomenon caused by the interaction of the fluctuated dc-link voltage and the motor phase voltage. In this paper, another form of the beat phenomenon generated by the fluctuated dc-link voltage and the severely fluctuated load torque is investigated. The effect of the beat phenomenon on the grid current and the motor speed is analyzed, which fluctuate with the low-frequency oscillation. In order to improve the drive system performance, a power balancing controller is proposed to suppress the grid current fluctuation, and a resonant controller is utilized to regulate the periodic power signals. Meanwhile, the applied fluctuated torque suppression method could improve the performance of the motor speed, which is only sensitive to the frequency of the fluctuated load torque. Experimental results are provided to verify the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

The LC resonance between the line inductor and the dc-link film capacitor is an important concern in the reduced dc-link capacitance interior permanent magnet synchronous motor drive system. In this paper, an active damping method based on the virtual damping resistor is applied to suppress the LC resonance and improve the drive system stability. The performance of the damping resistor is analyzed in a systematic level, and possible configurations have been analyzed to obtain the optimal solution, which is proved to be the inductor current feedback (ICF) damping method. In order to realize the equivalent damping effect, the dc-link voltage feedback is applied to emulate the ICF-based active damping method by a step-by-step approach. Meanwhile, the grid voltage distortion will stimulate additional harmonics of the grid current in the reduced dc-link capacitance motor drives. Hence a feedforward compensation method is applied to suppress the grid current distortion arising from the distorted grid voltage, which has not been investigated in the previous related researches. Harmonics of the grid current are reduced and requirements of EN61000-3-2 can be satisfied by applying the proposed method. Experiments on a compressor drive platform equipped with the reduced dc-link capacitance are performed to verify the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]