Circuits and methods for achieving high linearity, high efficiency power amplifiers, including digital predistortion (DPD) and pulse cancellation in switched-state RF power amplifier systems are described.

Linearization Circuits And Methods For Multilevel Power Amplifier Systems

For power quality in V/V traction system of the 350-km/h high-speed railway, a kind of railway static power conditioner (RPC) is discussed, which is used to carry out the comprehensive compensation of negative sequence and harmonic currents in the traction substation. In order to improve the control effect and performance of RPC, a dual-loop control strategy is constructed for RPC. Taking into account the disturbance and variation of electrified railway environment, a recursive proportional-integral control based on fuzzy algorithm is adopted to realize a fast and smooth tracking to the reference current. An energy-balance control is proposed to suppress the fluctuation of dc-link voltage and maintain the stability of RPC, which is an accurate and adaptive feedback control based on corresponding parameters. Finally, the correctness of the analysis proposed in this paper has been confirmed by the simulation and experiment results.

A Dual-Loop Control Strategy of Railway Static Power Regulator Under V/V Electric Traction System

Harmonic resonances in traction power supply systems (TPSSs) have attracted great attention due to their potentially destructive impact on the safe and stable operation of railways. Based on operation data acquired from Chinese railways, this paper presents a comprehensive review of this issue considering both academic and engineering requirements. Analyzing actual incidents, the general patterns and effects of TPSS resonances are derived. The relation between the TPSS and the locomotive is illustrated by circuit models. Relevant methods for modeling locomotives and TPSSs are discussed. Both advanced resonance analysis methods giving general influence factors and a simplified resonance analysis explaining resonance features in a practical manner are discussed. Multiple ground-based and on-board solutions for resonance elimination are presented. At last, preidentifying resonances in actual systems is investigated for addressing the open topic of resonance prevention.

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High-Order Harmonic Resonances in Traction Power Supplies: A Review Based on Railway Operational Data, Measurements, and Experience

A multi-level inverter having one or more banks, each bank containing a plurality of low voltage MOSFET transistors. A processor configured to switch the plurality of low voltage MOSFET transistors in each bank to switch at multiple times during each cycle.

Multi-level Inverter

An integrated power supply and modulator system includes integrated power supply and modulator system includes three subsystems: a switched-capacitor voltage balancer stage; a magnetic regulation stage; and at least one output switching stage In one embodiment, the integrated power supply and modulator system further includes startup circuitry, feedback/feedforward circuitry and control circuitry

Integrated power supply and modulator for radio frequency power amplifiers

The invention relates to a control method of three-phase voltage type PWM rectifier under unbalance voltage of a power grid, relates to the technical field of power electrons. The method comprises the following steps: detecting three-phase power grid voltage value, and transforming to be under a two-phase static coordinate system; carrying out digital filtering on an Alpha-axis voltage component and a Beta-axis voltage component under the two-phase static coordinate system by a positive-negative sequence filter, and obtaining the Alpha-axis positive-negative sequence component and Beta-axis positive-negative sequence component; calculating and obtaining the Alpha-axis and Beta-axis current instruction according to the Alpha-axis and Beta-axis positive-negative sequence voltage component under the given active and reactive power and two-phase static coordinate system; detecting three-phase alternating current, transforming to be under the two-phase static coordinate system, adopting a predicting current control method, calculating and obtaining Alpha-axis input voltage instruction and Beta-axis input voltage instruction of the alternating side under the two-phase static coordinate system. SVPWM modulation is adopted to obtain driving pulse. The control method eliminates direct current voltage harmonic component of three-phase PWM rectifier under the unbalance voltage of the power grid and realizes the operation of controlled power coefficient.

Control method of three-phase voltage type PWM rectifier under unbalance voltage of power grid

The invention discloses a module combined multi-level converter, and belongs to the technical field of multi-level conversion. Three-phase alternating current wire connecting terminals of a first power unit (U1) are connected in series with n third power units (U3) (n is a positive integer, same below) in turn to form a three-phase upper bridge arm, three-phase alternating current wire connecting terminals of a second power unit (U2) are connected in series with n fourth power units (U4) in turn to form a three-phase lower bridge arm, the three-phase upper bridge arm is connected with the three-phase lower bridge arm through two electric reactors, and a connecting point between the two electric reactors is a three-phase alternating current output end. A direct current wire connecting terminal of the first power unit (U1) is connected with an anode (101) of a direct current bus, and a direct current wire connecting terminal of the second power unit (U2) is connected with a cathode (102) of the direct current bus. By increasing or reducing the number n of the power units of the upper bridge arm and the lower bridge arm, the level number of the converter can be changed. The module combined multi-level converter preserves the advantages of the conventional multi-level converter, overcomes the defects of the conventional multi-level converter, and can be applied to an energy conversion system of medium-high voltage high-power occasions.

Module combined multi-level converter

The Chinese railways are characterized by a wide range of various locomotive series. Nowadays, 80% of the locomotives driven by electricity run on the most main railroads. Most of the electric locomotives designed by AC-DC traction system till 2003 while DJ1 locomotives manufactured by AC-DC-AC traction system. Power Electronics is one of the pivotal parts of the whole locomotive equipment, playing important roles in power outputting, traction torque releasing, brake dynamic inflicting etc. This paper probes into 3 ages of the power electronics technology used in the electrical locomotives in China. The line-commutated control (thyristor and diodes) and the line-commutated control (thyristor and diodes) in traction and auxiliary system delegates the different age. Problems in system design concerning match of invert and asynchronous traction motor are discussed. Main circuit diagram, power electronics and general technical parameters are presented. At last, The paper gives a comparison of the traction characteristic for the electrical locomotive in different age.

Power electronics used in Chinese electric locomotives

The invention discloses a weak magnetic control method for a permanent magnet synchronous motor. The method comprises the following steps that: direct axis current instructions are obtained through a motor rotating speed regulator; and instruction values of motor alternating axis voltage are obtained by calculation through the direct axis voltage instruction value output by a motor direct axis current regulator and the maximum voltage value output by an inverter, and the motor voltage is guaranteed to reach the maximum value at the weak magnetic interval. The method provided by the invention can be used for solving the problem of nonideal system control effect caused by alternating and direct axis current coupling in weak magnetic control, and in addition, the voltage utilization rate can be improved.

Weak magnetic control method for permanent magnet synchronous motor

The invention belongs to power supply, in particular to a method for suppressing line-side harmonics of a magnetic-levitation train tractive power supply system capable of feeding back braking energy.The method comprises the following steps: a controller transforms an input current and an input voltage of an alternating current-direct current (AC-DC) transformation device into a current and a voltage in a rotating coordinate system by dq coordinate transformation; after the current and the voltage pass by a low-pass filter, the current is projected in a voltage direction, the projection is compared with an adjusted difference value between a positive DC bus and a negative DC bus by a proportional integral controller to obtain projections of a current active component on a q-axis and a d-axis; the projections on the q-axis and the d-axis are inversely transformed from a phase-locked ring at an angular frequency extracted from the input voltage to obtain a fundamental wave current active component; the difference of the fundamental wave current active component and the input current is a compensating current component which is compared with a practically measured AC of a three-phasefour-quadrant converter to obtain an error signal; and the turn-on time and the duty ratio of each power switching tube of the three-phase four-quadrant converter are calculated by using the error signal and a deadbeat predictor current control method, thereby sending out a PWM control signal of each power switching tube.

Liwei Zhang

Papers

Control method of three-phase voltage type PWM rectifier under unbalance voltage of power grid

Module combined multi-level converter

Power electronics used in Chinese electric locomotives

Weak magnetic control method for permanent magnet synchronous motor

Method for suppressing line-side harmonics of magnetic-levitation train tractive power supply system capable of feeding back braking energy