Corrección de factor de potencia basada en la estimación digital de la corriente de línea: aplicación en el convertidor Boost en modo de conducción continua

• Autores: Víctor Manuel López Martín
• Directores de la Tesis: Francisco Javier Azcondo Sánchez (dir. tes.)
• Lectura: En la Universidad de Cantabria ( España ) en 2013
• Idioma: español
• Número de páginas: 226
• Tribunal Calificador de la Tesis: Paolo Mattavelli (presid.), Alberto Pigazo López (secret.), Javier Sebastián Zúñiga (voc.)
• Materias:
  • Ciencias tecnológicas
    • Tecnología electrónica
• Enlaces
  • Tesis en acceso abierto en: UCrea
• Resumen
  • español

    En esta tesis se presenta un controlador digital universal de corrección de factor de potencia basado en la estimación digital de la corriente de entrada. En dicha estimación se tiene en cuenta todas las fuentes de error en la estimación de la corriente debido a la implementación real del estimador, que introducen una diferencia entre la tensión medida en la inductancia y la real (tanto en términosde voltios como en términos de tiempo). Para compensar esta desviación. Una compensación feedforward para compensar errores con la variable tiempo, y un lazo de realimentación digital feedback que cancela la diferencia de tiempos el modo de conducción discontinua (MCD) de la corriente real de entrada (TgDCM) y de la corriente digital reconstruida (TrebDCM). Se presenta además una modificación en el control no-lineal de corrección de factor de potencia (NLC), para asegurar una corriente sinusoidal ante tensiones de red distorsionadas. Los resultados experimentales, obtenidos con un Boost PFC bajo diferentes condiciones muestran el comportamiento del control propuesto.

  • English

    Continuous conduction mode (CCM) power factor correction (PFC) without input current measurement is a step forward with respect to previously proposed PFC digital controllers. Inductor volt-second (vsL) measurement in each switching period enables the digital estimation of the input current, used in the inner current loop. However, an accurate compensation of the small inaccuracies in the measured vsL is required in the estimation, to match the actual current. Otherwise, these errors are accumulated every switching period over the half-line cycle, leading to an appreciable current distortion. A vsL estimation method is proposed in this thesis, measuring the input (vg) and the output voltage (vo). Discontinuous measuring the drain-to-source MOSFET voltage, vds. Parasitic elements also cause a small difference between the estimated voltage across the inductor, based on input and output voltage measurements, and the actual one, which must be taken into account to estimate the current in the proposed sensorless PFC digital controller. This thesis analyzes deeply the current estimation inaccuracies caused by errors in the ON-time estimation, voltage measurements, and the parasitic elements. A new digital feedback control with high resolution is also proposed to cancel the difference between DCM operation time of the real input current TgDCM, and the estimated DCM time TrebDCM. Therefore, the current estimation is calibrated using digital signals during in DCM. A fast feedforward coarse time error compensation is carried out with the measured delay of the drive signal, and then a fine compensation is achieved with the feedback loop that matches the estimated and DCM times. With this contribution, an universal controller is proposed. The digital controller can be used in universal applications due to the ability of the DCM time feedback loop to autotune based on the operation conditions (power level, input voltage, output voltage...), which improves the operation range in comparison with previous solutions. Furthermore, an additional improvement is presented in this controller which the current demanded by the Sensorless PFC rectifier is pure sinusoidal despite the non-sinusoidal input voltage of the grid. This contribution is really interesting in applications where the harmonic limits are stricter (like in aircraft systems) and must be fulfilled independently on the voltage waveshape. This modification is totally done into the digital controller without any need of extra analogs components. Experimental results are shown for a 1 kWboost PFC converter over a wide power and voltage range. The digital controller is implemented in a field programmable gate array (FPGA) with a very simple analog circuitry to adapt the signals needed by the controller. The behaviour of the controller, applied in lighting systems, is also shown.