Voltage Source Rectifier Research Articles

Optimal Control of Sinusoidal Input Current Three Phase PWM Rectifiers.

A new design method based on the linear-quadratic control theory is developed for the control of PWM rectifiers with sinusoidal input current. The PWM rectifiers are promising because they can supply DC power while keeping a sinusoidal AC current with unity in the fundamental power factor. There are two types, a voltage-source rectifier and a current-source rectifier. The former is required to simultaneously control both the fundamental power factor and DC voltage, while the latter does so for both the fundamental power factor and DC current. State feedback control is essentially suited for multi-input and multi-output systems such as those. Here a discrete-time optimal regulator is applied to their control because it provides a microprocessor-based robust feedback system without steady-state errors in response to step reference and/or disturbance change. The regulator is implemented using a digital-signal-processor. Experimental results demonstrate the validity.

Variable structure control of voltage sourced reversible rectifiers

The principal result of the paper is a novel control scheme for the voltage sourced reversible rectifier based on variable structure control (VSC) techniques. A time-scale separation property of the rectifier dynamics is identified. This is exploited by using singular perturbation methods to reduce the model order. Conditions are given for global stability. Simulation results are presented for the reversible rectifier operating with a simple type of VSC. These demonstrate an excellent dynamic performance. The design process and experimental results for a conventional space vector modulated control scheme are included for comparison.

A novel load current control method for a leading power factor voltage source PWM rectifier

A novel PWM voltage source rectifier, controlled by the load DC current instead of the DC voltage, has been developed. Its main characteristics are: (a) there is neither input current sensors nor DC voltage sensor; (b) it works with an unchangeable and predefined PWM pattern; (c) it presents a very strong stability; (d) its stability does not depend on the size of the DC capacitor; (e) it can work at leading power factor for all load conditions; and (f) it can also work with zero regulation for all load conditions. Digital simulations, analyses, and experiments confirm all these characteristics of the control method. >

A space vector-based rectifier regulator for AC/DC/AC converters

A voltage-sourced rectifier control scheme for use with AC/DC/AC variable speed drives is presented. A control scheme is derived that directly calculates the duration of time spent on the zero state and on each switching state adjacent to the reference vector, over a constant switching interval, in order to drive the line current vector to the reference vector. In addition, under transient conditions, when deadbeat control is not possible, a control scheme is presented that ensures that the line current vector is driven in the direction of the reference current vector. The current reference for the rectifier controller is derived from the bus voltage error and a feedforward term based on the estimated converter output power. The proposed space vector-based rectifier regulator is shown to exhibit improved harmonic and transient performance over existing per-phase duty cycle prediction methods, especially at modulation indices near unity. The deadbeat control of the rectifier input current is accomplished every half-cycle with constant switching frequency while still symmetrically distributing the zero state within the half-cycle period. >

Angle controlled current regulated rectifiers for AC/AC converters

Rectifier control schemes for use in AC-DC-AC voltage-sourced resonant link converters with controlled rectifiers are discussed. Resonant link converters require the use of discrete pulse modulation. Control of the AC-to-DC converter by means of averaging methods or duty-cycle control is not inherent with this type of modulation. However, it is shown that the voltage-sourced rectifier cannot be operated solely on the basis of instantaneous quantities. A bang-bang control scheme is developed which independently controls the angle and the magnitude of the AC line current vector. The magnitude of the current is controlled using a linear combination of the link voltage error and the current magnitude error. The current reference is derived by the use of load torque estimation. In addition, the current vector that satisfies the sliding-mode criteria and results in the lowest voltage ripple is chosen to further minimize the size of the link capacitor. >

Hysteresis current-forced three-phase voltage-sourced reversible rectifier

A voltage-sourced reversible rectifier (VSRR) which achieves bidirectional power flow between a three-phase AC supply and a DC bus voltage is described. The device features a current-forced control strategy that has the advantages of simplicity and extremely fast response time, while operating with unity power factor and sinusoidal AC supply currents to produce a regulated DC bus voltage. Six power transistors provide the necessary control over the currents, and to prevent them from switching faster than their capability a hysteresis band is introduced into the control strategy. The paper investigates the effects of the hysteresis, inductance and transistor switching delays on switching rates, distortion and efficiency by using both simulated and experimentally obtained results.