Three-phase Switch-mode Rectifier Research Articles

Development of Digital Control for High Power Permanent-Magnet Synchronous Motor Drives

This paper is concerned with the development of digital control system for high power permanent-magnet synchronous motor (PMSM) to yield good speed regulation, low current harmonic, and stable output speed. The design of controller is conducted by digitizing the mathematical model of PMSM using impulse invariance technique. The predicted current estimator, which is insensitive to motor feedback currents, is proposed to function under stationary frame for harmonic current suppression. In the AC/DC power converter, mathematical model anddc-link voltage limit of the three-phase switch-mode rectifier are derived. In addition, a current controller under synchronous frame is introduced to reduce the current harmonics and increase the power factor on the input side. A digital control system for 75 kW PMSM is realized with digital signal processor (R5F5630EDDFP). Experimental results indicate that the total harmonic distortion of current is reduced from 4.1% to 2.8% for 50 kW output power by the proposed predicted current estimator technique.

A Control Strategy for Output Maximisation of a PMSG-Based Variable-Speed Wind Turbine

This paper presents a control strategy for output maximisation of a direct drive permanent magnet synchronous generator (PMSG)-based small-scale variable-speed wind turbine. The control topology uses a single switch three-phase switch-mode rectifier and the generator torque, and power is controlled by controlling the switch duty cycle of the switch. To extract maximum power from the wind, the torque reference of the PMSG is calculated from generator speed and wind turbine characteristics. From this torque reference, a current reference is calculated using measured DC link voltage and generator speed. The current error is then used to control the duty cycle of the switch-mode rectifier and thereby torque of the generator is regulated through a proportionalintegral regulator. The operational characteristics of the generating system are investigated under varying wind speed through extensive simulations and the results confirm that the proposed control strategy can maximise the output power under fluctuating wind speeds.

A digitally controlled switch mode power supply based on matrix converter

High power telecommunication power supply systems consist of a three-phase switch mode rectifier followed by a dc/dc converter to supply loads at -48 V dc. These rectifiers draw significant harmonic currents from the utility, resulting in poor input power factor with high total harmonic distortion (THD). In this paper, a digitally controlled three-phase switch mode power supply based on a matrix converter is proposed for telecommunication applications. In the proposed approach, the matrix converter directly converts the low frequency (50/60Hz, three-phase) input to a high frequency (10/20kHz, one-phase) ac output without a dc-link. The output of the matrix converter is then processed via a high frequency isolation transformer to produce -48V dc. Digital control of the system ensures that the output voltage is regulated and the input currents are of high quality under varying load conditions. Due to the absence of dc-link electrolytic capacitors, power density of the proposed rectifier is expected to be higher. Analysis, design example and experimental results are presented from a three-phase 208-V, 1.5-kW laboratory prototype converter.

SEPIC derived three-phase switching mode rectifier with sinusoidal input current

A SEPIC derived three-phase rectifier is proposed to achieve clean sinusoidal input current, unity power factor, step up/down DC voltage and to be insensitive to input voltage distortion. Depending upon how many boost modes are chosen and which class of generalised zero voltage space vector is selected to obtain the equivalent DC duty cycle, different control strategies can be obtained. It is seen that through introduction of an equivalent duty cycle the DC/DC SEPIC converter function can be maintained without affecting the desired rectifier characteristic. The input to output voltage gain for two control strategies is also derived. Finally, a hardware implementation example and some experimental results are given to demonstrate the validity of the proposed rectifier.

A novel simplified space-vector-modulated control scheme for three-phase switch-mode rectifier

A novel simplified control scheme for a three-phase switch-mode rectifier is proposed in this paper. The proposed control scheme is based upon a load-conductance rectifier controller, in which reference current signals are obtained. The goal to follow the reference current is converted to follow a reference voltage. A simplified control scheme utilizing space-vector modulation is developed to calculate the duty ratio required to synthesize the reference voltage. The proposed scheme has the advantage of space-vector modulation with fast dynamic response and is simple enough to be implemented in a single-chip microprocessor 80196MC.

A new space-vector-modulated control for a unidirectional three-phase switch-mode rectifier

A unidirectional three-phase switch-mode rectifier that delivers sinusoidal input currents in phase with the corresponding input phase voltages is proposed and analyzed in this paper. In the proposed topology, three AC switches are placed before the bridge rectifier and, respectively, across two power lines. A simple control scheme combing space-vector modulation and hysteresis current control is presented. Sinusoidal input line currents are observed in experimental results.

Modelling and design of a reversible three-phase switching mode rectifier

A reversible three-phase switching mode rectifier consisting of a four-active-switch and without current sensor is proposed. To achieve controllable power factor, clean sinusoidal input current, adjustable DC output voltage, and bidirectional power flow capability, a closed-form pulse width modulation (PWM) duty cycle function is derived. The popularly used state space averaging technique is extended for modelling the reversible three-phase four-active-switch rectifier. The space vector representation technique is then used to simplify the modelling process without sacrificing accuracy and valid frequency range. Both steady-state and small signal analyses are made. Results show that the proposed closed-form control law for the rectifier can indeed achieve the desired property. Moreover, the rectifier also possesses a bidirectional power flow capability, which is useful for many applications. Finally, a prototype hardware circuit was constructed and experimental results are presented for demonstration. Guidelines for determining the LC parameters and the PI controller gains are described briefly in the text.

Three-phase switch mode rectifier with hysteresis current control

A three-phase configuration of a switch mode rectifier (SMR) that makes use of continuous conduction waveform of the input supply current is suggested. Continuous conduction is achieved by the hysteresis current control (HCC) technique. This three-phase SMR operates at close to unity power factor and has reduced current stresses on the switching devices because of the continuous nature of input current. The conduction period considered for the rectifier diodes is 180/spl deg/. Digitally simulated performance results are provided. Selected experimental results demonstrating the SMR operation are also presented.

Novel three-phase SMR converter with inherent snubber energy recovery capability

This paper describes the switch mode rectifier (SMR) having a quite new circuit configuration, which has been developed by the authors and given the name "DC clamped type SMR" (DCC-SMR). The DCC-SMR is unique in that no bilateral switching device is used in the frequency conversion circuit. Therefore, the authors have used a DC snubber circuit in conjunction with the switching device of the DCC-SMR. This DC snubber circuit features a very simple structure consisting only of a capacitor with no need for a discharge resistance or for a complicated regenerative circuit for snubber energy. This is because snubber energy is regenerated on the primary side of the high frequency (HF) transformer by the main switch. Furthermore, an innovative method has been applied for magnetic saturation-preventive control of the HF transformer. The authors carried out operational checks on the main circuit and the snubber circuit of the DCC-SMR as well as on the magnetic saturation-preventive control circuit, and through experiments confirmed a satisfactory result. We manufactured an industrial DC power supply prototype of the DCC-SMR system having a DC output of 100 kW (100 V, 1000 A), with which input/output conversion efficiency 91.6%, input power factor 0.99 and input current total harmonic distortion factor 4.6% were obtained.

Novel Three-phase SMR Converter.

We already developed a conventional SMR (Switch Mode Rectifier) converter using bilateral switch. A conventional SMR converter has a weak point that is to be need of AC snubber circuit and the complicated circuit for regeneration of snubber energy.This paper discribes a novel three-phase SMR converter which was named DC-Clamped type SMR ( DCC-SMR ) using direct frequency changing technology for industrial use power supply. DCC-SMR consists of frequency changer, HF (High Frequency) transformer and HF rectifier. Frequency changer of DCC-SMR doesn't use bilateral switch. Then, we can use DC snubber for switch. Furthermore, DCC-SMR doesn't-need regenerative circuit and discharge resistance, because snubber circuit is only capaciter and snubber energy is regenerated to primary winding of HF transformer by main switch.We verified usefulness in experimentation. Moreover, we refer to efficiency of 100kw prototype system.

Analysis and design of a three-phase offline DC-DC converter with high-frequency isolation

Single-phase offline switch mode rectifiers (or offline DC-DC converters) face severe component stresses in higher than 10kW applications. The authors show that in three-phase, switch-mode rectifier (SMR) topologies' component stresses are reduced, and performance is improved substantially. These improvements include faster response times, reduced switching stresses of the power semiconductor devices, and reduced size and ratings of associated reactive components. The authors also present an analysis and design approach for three-phase SMR converters under large-input voltage and load variations. Output voltage control is achieved by varying the duty cycle of the inverter power semiconductor switches. Theoretical results are verified experimentally. >