Jiangang Hu

Dynamic Modeling and Analysis of

This paper contributes to the AC small signal modeling and analysis of Z source converter (ZSC) in continuous conduction mode. The AC small signal model considers the dynamics introduced by Z network uniquely contained in ZSC. AC small signal model of ZSC is derived and computer simulation results are used to validate the small signal modeling method. Various applications of the AC small signal models to ZSC design and experimental verifications are presented.

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In this paper, a cascade controller is designed and analyzed for a boost converter. The fast inner current loop uses sliding-mode control. The slow outer voltage loop uses the proportional-integral (PI) control. Stability analysis and selection of PI gains are based on the nonlinear closed-loop error dynamics. It is proven that the closed-loop system has a nonminimum phase behavior. The voltage transients and reference voltage are predictable. The current ripple and system sensitivity are studied. The controller is validated by a simulation circuit with nonideal circuit parameters, different circuit parameters, and various maximum switching frequencies. The simulation results show that the reference output voltage is well tracked under parametric changes, system uncertainties, or external disturbances with fast dynamic transients, confirming the validity of the proposed controller.

Source Converter—Derivation of AC Small Signal Model and Design-Oriented Analysis

High-frequency current responses of a permanent magnet synchronous machine (PMSM), with and without considering eddy current effects, are significantly different. This paper investigates the eddy current effects on rotor position estimation. A compensation method is developed to improve the high-frequency-injection-based rotor position estimation of a PMSM at zero and low speeds. The paper also contributes to an improved magnetic pole identification based on space vector pulse width modulation for an arbitrary initial rotor position. The estimation and sensorless control method of PMSM, considering eddy current effects, has been verified by experimental results.

Closed-Loop Analysis and Cascade Control of a Nonminimum Phase Boost Converter

In this paper, an AC small-signal equivalent circuit model of continuous conduction mode (CCM) ZSI based on state space averaging is presented. The AC small-signal model includes the dynamics of ZSI introduced by the inductors and capacitors contained in the ZSI circuit, providing guidelines to the system control design. In addition, a novel modified space vector PWM is presented to distribute the shoot-through states into the zero vectors without compromise to the active space vector. Simulation results based on the design are presented, using the proposed SVPWM control strategy

Eddy Current Effects on Rotor Position Estimation and Magnetic Pole Identification of PMSM at Zero and Low Speeds

This paper contributes to an improved magnetic pole identification based on space vector PWM for an arbitrary initial rotor position of PM synchronous machines. The principle of magnetic pole identification is discussed and the N-S pole identification method based on space vector PWM presented. The improved identification method is verified by experiment results

A modified space vector PWM for Z-source inverter-modeling and design

The paper discusses the issues and provides solutions to digital implementation of sliding mode observer (SMO), especially for sensorless controlled induction machine (IM) operating over a wide speed range. An adaptive low pass filter (LPF) is proposed with variable cut-off frequency for a wide speed range, including a programming technique of using over-sampling to increase the sampling rate seen by the SMO. The sampling rate is made much higher than the system PWM frequency. Methods of designing proper gain are given for a specific SMO. Simulation and experimental results based on the fixed-point DSP TMS320F2812 are provided to verify the effectiveness of the proposed methods

Magnetic Pole Identification for PMSM at Zero Speed Based on Space Vector PWM

High-frequency current responses of a PM synchronous machine with and without considering the eddy current effects are significantly different. This paper identifies and investigates the eddy current effects on rotor position estimation. Compensation method is developed to improve high-frequency-injection-based sensorless control of a PM synchronous machine at zero and low speeds. The estimation and sensorless control method, considering eddy current effects, has been verified by experimental results

Sliding Mode Observer for Wide Speed Range Sensorless Induction Machine Drives: Considerations for Digital Implementation

Design and control of a kilo-amp voltage source DC/AC inverter suitable for low voltage integrated starter-generator (ISG) operation is presented. Multiparallel MOSFETs are used to achieve extremely high current capability. Issues related to power module integration, filtering components and thermal management are discussed. A prototype with current capability up to 1500 amps is designed and built to validate the kilo-amp inverter. A sensorless control scheme based on indirect flux orientation (IFO) in ISG application is studied. Computer simulation and experimental results are presented for verification.

Eddy Current Effects on Rotor Position Estimation for Sensorless Control of PM Synchronous Machine

Compared with conventional field orientation control (FOC), the proposed algorithm achieves induction generator objectives using only one regulator based on the principle of indirect field orientation control. By means of direct control of the slip angular velocity and full utilization of the DC bus voltage, the currents projected onto the d- and q-axes are self tuned in high speed range without any conflicting regulations, resulting in stable and constant power delivering in a flux weakening level of 1/4.3. Moreover, the close-loop slip regulation automatically compensates errors from the estimation of the rotor flux angle and speed, and therefore makes the system robust. Simulation and experimental results on a 10 kW induction generator system are presented to verify the effectiveness of the proposed algorithm.