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This paper presents a new technique to detect the junction temperature of Silicon Carbide (SiC) MOSFET devices. The process of detection is based on injecting a high frequency/low amplitude sweep signal into the gate lead of a SiC device during its OFF-state period. A frequency response analysis is carried out to determine the variation in the impedance which is a function of temperature change. The...
With the fast development of distributed power generations, stability and security have attracted extensive attention in the recent years. As a representative of clean energies, Photovoltaic (PV) systems have been installed extensively worldwide. This drives grid-connected requirements to be continuously updated. In current active grid requirements/codes, PV systems should be more intelligent in the...
This paper proposes an advanced model predictive control for the three-level active-neutral-point-clamp (ANPC) inverter in order to improve the system performance with fast dynamic response and ensure the stability of the controller. The proposed scheme is Lyapunov function based voltage mode control which utilizes the discrete behavior of the converter considering the unavoidable quantization errors...
In this paper, an improved control strategy for three-phase inverter is proposed, which ensures three-phase output voltage symmetry under unbalanced grid voltage. Firstly, the positive and negative sequence separation module is used to obtain unbalance output voltage and current during the grid faults. By calculating output power of the inverter, an improved P-ƒ, Q-U and Q-G droop control strategy...
This paper focuses on the high frequency current injection method for sensorless control of surface mounted permanent magnet synchronous machines (SPMSM) at low speed. In sensorless control of injection method, a PI close loop is needed to estimate the rotor position. However, constant PI parameters are unable to achieve optimal control effect in both process of dynamic and steady-state. In this paper,...
The converter valve is the critical link of AC and DC system and the most commonly used switching devices for converter valve are thyristors. The performance of thyristors could significantly affect the performance of converter valve while the transient characteristics and second order effects of thyristor are critical to determine the reliability of converter valve in HVDC (High Voltage Direct Current)...
In the conventional variable speed drive, the dc-link including the dc-choke and electrolytic capacitor is bulky with limited lifetime. The slim dc-link drive is thus proposed for the lower cost and longer lifetime by using the film capacitor to replace the electrolytic capacitor and dc-choke. However, such drive system suffers from the potential instability issue, due to the negative incremental...
Distributed control methods generally implemented with droop control have been widely applied in the energy management of microgrids. However, the robustness and stability of distributed control has been influenced by the size and diversity of the microgrid structure and compositions. Meanwhile, centralized control has been considered lack of flexibility and expansibility. In this paper, a novel control...
This paper discusses the effect of current measurement error in angle estimation of permanent magnet AC motor for position sensorless control based on motor back EMF. The current measurement errors due to non-ideal elements in the system are classified into the scaling error, the offset error, and the discretization error. Those errors have been represented in the estimated synchronous reference frame...
Interleaved Multi-phase DC/DC Converters (IMDDC) with Integrated Magnetic Components (IMC) are well-known as one of the converter topologies that can achieve high-power-density. However, as one of the drawbacks of IMDDCs, the power conversion efficiency when all phases are driven may decrease between light and middle loads. The main causes of the efficiency reduction are non-load losses caused by...
HV n-/p-LDMOS devices with the source-side extending into bulk-region to evaluate the electrostatic-discharge (ESD) protection robustness by a TSMC 0.25 µm 60 V process are investigated in this paper. After a systematic analysis, the trigger voltage (Vt1) values of the n-LDMOS with the source-side extending into the bulk-end either by uniformly or non-uniformly distributed manners that had decreased...
This paper discusses an optimized switching pattern for reducing an input current distortion of a matrix converter using a space vector modulation. The matrix converter has 27 instantaneous output voltage / input current patterns. In order to keep low input current distortion, the matrix converter always must select optimized switching pattern. A space vector modulation is one of solution of these...
High reliability performance of microinverters in Photovoltaic (PV) systems is a merit to match lifetime with PV panels, and to reduce the required maintenance efforts and costs. This paper applies a reliability oriented design method for a grid-connected PV microinverter to achieve specific lifetime requirement. Reliability allocation is performed from the system-level requirement to the component-level...
As the penetration level of grid-connected PV systems increases, more advanced control functionality is demanded. In order to ensure smooth and friendly grid integration as well as enable more PV installations, the power generated by PV systems needs to be flexible and capable of: 1) limiting the maximum feed-in power, 2) ensuring a smooth change rate, and 3) providing a power reserve. Besides, such...
This paper presents the suppression control of the source current harmonics of the bi-directional isolated AC/DC converter. The proposed circuit consists of three-phase AC to high-frequency single-phase AC matrix converter, high-frequency transformer, and single-phase AC to DC converter. The authors have achieved the soft-switching of all commutations of the both converters. The further downsizing...
In this paper, a novel valley-fill snubber circuit for a three-phase PWM inverter is proposed. One advantage of the valley-fill snubber is that surge voltage suppression is achieved without the power loss that happens in a conventional snubber resister. The second advantage is that ZVS/ZCS operation is realized without using additional active switches. Hence, the proposed snubber circuit is effective...
This paper discusses operating characteristics of a permanent magnet synchronous motor (PMSM) drive system based on direct torque control (DTC). In this system, the whole control system works in a rotating reference frame that is synchronized with the stator flux linkage vector (called M-T frame). The stator flux estimation is also based on a PMSM model in the M-T frame, and thus, this is expected...
A pattern matching method for position sensorless control of IPMSMs having non-sinusoidal inductance spatial distribution in standstill and very low speed region has been proposed. In the proposed method, the rotor position is estimated by comparing the phase current derivatives measured in a real-time with those in advanced. The current derivatives are obtained by measuring the phase currents twice...
This paper analyzes the conducted noise generation mechanism of totem-pole bridgeless PFC converter in consideration of frame ground capacitor and LISN at every input voltage zero-crossing. The spike current occurs at zero-crossing and causes severe common mode noise. The frequency range on noise spectrum caused by zero-crossing issue is discussed by mathematical calculation. Furthermore, the experimental...
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