Method and system for controlling power factor correction circuit
View Patent ↗An embodiment method for controlling a power factor correction circuit includes detecting an AC zero voltage crossing point, detecting a current flowing through an inductor, and reducing a distortion of the current flowing through the inductor by determining a current at the AC zero voltage crossing point as a resistive current, an inductive current, or a capacitive current and controlling each of a plurality of switching elements from a time point when the AC zero voltage crossing point is detected based upon a result of determining the current.
1. A method for controlling a power factor correction circuit, the method comprising:
detecting an AC zero voltage crossing point;
detecting a current flowing through an inductor; and
reducing a distortion of the current flowing through the inductor by determining a current at the AC zero voltage crossing point as a resistive current, an inductive current, or a capacitive current and controlling each of a plurality of switching elements from a time point when the AC zero voltage crossing point is detected based upon a result of determining the current.
2. The method of claim 1 , wherein reducing the distortion of the current flowing through the inductor comprises deriving a q-axis current component from the current flowing through the inductor and determining whether the current at the AC zero voltage crossing point is the resistive current, the inductive current, or the capacitive current based on the q-axis current.
3. The method of claim 1 , wherein reducing the distortion of the current flowing through the inductor comprises reducing the distortion of the current flowing through the inductor by controlling each of the plurality of switching elements from the time point when the AC zero voltage crossing point is detected to minimize the voltage applied to the inductor.
4. The method of claim 1 , wherein detecting the crossing point comprises determining a transition point from a negative voltage to a positive voltage or a transition point from the positive voltage to the negative voltage as the AC zero voltage crossing point by detecting a polarity of the AC voltage.
5. The method of claim 4 , wherein reducing the distortion of the current flowing through the inductor comprises controlling each of the plurality of switching elements based on a type of the AC zero voltage crossing point and the result of determining the current.
6. The method of claim 1 , wherein:
the plurality of switching elements comprises a first switching element and a second switching element of a first leg of a full-bridge structure and a third switching element and a fourth switching element of a second leg of the full-bridge structure; and
controlling each of the plurality of switching elements comprises independently controlling each of the plurality of switching elements in a first section, a second section, and a third section and PWM-controlling the plurality of switching elements based on duties at a time point before the first section and a time point after the third section, wherein a first time point is a point of the AC zero voltage crossing point.
7. The method of claim 6 , wherein, in response to a determination that the AC zero voltage crossing point is a crossing point from a negative voltage to a positive voltage and the current at the AC zero voltage crossing point is the inductive current, reducing the distortion of the current flowing through the inductor comprises controlling each of the first switching element, the second switching element, the third switching element, and the fourth switching element in each of the first section, the second section, and the third section such that:
in the first section, the first switching element is off, the second switching element is off, the third switching element is on, and the fourth switching element is off;
in the second section, the first switching element is off, the second switching element is on, the third switching element is off, and the fourth switching element is off; and
in the third section, the first switching element is off, the second switching element is on, the third switching element is off, and the fourth switching element is on.
8. The method of claim 6 , wherein, in response to a determination that the AC zero voltage crossing point is a crossing point from a positive voltage to a negative voltage and the current at the AC zero voltage crossing point is the inductive current, reducing the distortion of the current flowing through the inductor comprises controlling each of the first switching element, the second switching element, the third switching element, and the fourth switching element in each of the first section, the second section, and the third section such that:
in the first section, the first switching element is off, the second switching element is off, the third switching element is off, and the fourth switching element is on;
in the second section, the first switching element is on, the second switching element is off, the third switching element is off, and the fourth switching element is off; and
in the third section, the first switching element is on, the second switching element is off, the third switching element is on, and the fourth switching element is off.
9. The method of claim 6 , wherein, in response to a determination that the AC zero voltage crossing point is a crossing point from a positive voltage to a negative voltage and the current at the AC zero voltage crossing point is the capacitive current, reducing the distortion of the current flowing through the inductor comprises controlling each of the first switching element, the second switching element, the third switching element, and the fourth switching element in each of the first section, the second section, and the third section, such that:
in the first section, the first switching element is off, the second switching element is on, the third switching element is off, and the fourth switching element is off;
in the second section, the first switching element is off, the second switching element is off, the third switching element is on, and the fourth switching element is off; and
in the third section, the first switching element is on, the second switching element is off, the third switching element is on, and the fourth switching element is off.
10. The method of claim 6 , wherein, in response to a determination that the AC zero voltage crossing point is a crossing point from a negative voltage to a positive voltage and the current at the AC zero voltage crossing point is the capacitive current, reducing the distortion of the current flowing through the inductor comprises controlling each of the first switching element, the second switching element, the third switching element, and the fourth switching element in each of the first section, the second section, and the third section, such that:
in the first section, the first switching element is on, the second switching element is off, the third switching element is off, and the fourth switching element is off;
in the second section, the first switching element is off, the second switching element is off, the third switching element is off, and the fourth switching element is on; and
in the third section, the first switching element is off, the second switching element is on, the third switching element is off, and the fourth switching element is on.
11. A system for controlling a power factor correction circuit, the system comprising:
an AC voltage detection unit;
an inductor;
a full-bridge circuit;
a current sensor configured to detect a current flowing through the inductor; and
a controller configured to reduce a distortion of the current flowing through the inductor by detecting an AC zero voltage crossing point, determining the current flowing through the inductor at the AC zero voltage crossing point as a resistive current, an inductive current, or a capacitive current, and controlling each of a plurality of switching elements from a time point when the AC zero voltage crossing point is detected based on a result of determining the current.
12. The system of claim 11 , wherein the controller is configured to reduce the distortion of the current flowing through the inductor by controlling each of the plurality of switching elements from the time point when the AC zero voltage crossing point is detected to minimize a voltage applied to the inductor.
13. The system of claim 11 , wherein the controller is configured to:
determine a case in which a polarity of the AC voltage detected by the AC voltage detection unit becomes a transition point from a negative voltage to a positive voltage or from the positive voltage to the negative voltage as the AC zero voltage crossing point; and
control each of the plurality of switching elements based on a type of the AC zero voltage crossing point and the result of determining the current.
14. The system of claim 11 , wherein the full-bridge circuit comprises a first switching element and a second switching element constituting a first leg and a third switching element and a fourth switching element constituting a second leg.
15. The system of claim 14 , wherein the controller is configured to:
independently control each of the first switching element, the second switching element, the third switching element, and the fourth switching element in a first section, a second section, and a third section; and
PWM-control the plurality of switching elements based on duties at a time point before the first section and a time point after the third section, wherein a first time point is a point of the AC zero voltage crossing point.
16. The system of claim 15 , wherein, in response to a determination that the AC zero voltage crossing point is a crossing point from a negative voltage to a positive voltage and the current at the AC zero voltage crossing point is the inductive current, the controller is configured to reduce the distortion of the current flowing through the inductor by controlling each of the first switching element, the second switching element, the third switching element, and the fourth switching element in each of the first section, the second section, and the third section such that:
in the first section, the first switching element is off, the second switching element is off, the third switching element is on, and the fourth switching element is off;
in the second section, the first switching element is off, the second switching element is on, the third switching element is off, and the fourth switching element is off; and
in the third section, the first switching element is off, the second switching element is on, the third switching element is off, and the fourth switching element is on.
17. The system of claim 15 , wherein, in response to a determination that the AC zero voltage crossing point is a crossing point from a positive voltage to a negative voltage and the current at the AC zero voltage crossing point is the inductive current, the controller is configured to reduce the distortion of the current flowing through the inductor by controlling each of the first switching element, the second switching element, the third switching element, and the fourth switching element in each of the first section, the second section, and the third section such that:
in the first section, the first switching element is off, the second switching element is off, the third switching element is off, and the fourth switching element is on;
in the second section, the first switching element is on, the second switching element is off, the third switching element is off, and the fourth switching element is off; and
in the third section, the first switching element is on, the second switching element is off, the third switching element is on, and the fourth switching element is off.
18. The system of claim 15 , wherein, in response to a determination that the AC zero voltage crossing point is a crossing point from a positive voltage to a negative voltage and the current at the AC zero voltage crossing point is the capacitive current, the controller is configured to reduce the distortion of the current flowing through the inductor by controlling each of the first switching element, the second switching element, the third switching element, and the fourth switching element in each of the first section, the second section, and the third section, such that:
in the first section, the first switching element is off, the second switching element is on, the third switching element is off, and the fourth switching element is off;
in the second section, the first switching element is off, the second switching element is off, the third switching element is on, and the fourth switching element is off; and
in the third section, the first switching element is on, the second switching element is off, the third switching element is on, and the fourth switching element is off.
19. The system of claim 15 , wherein, in response to a determination that the AC zero voltage crossing point is a crossing point from a negative voltage to a positive voltage and the current at the AC zero voltage crossing point is the capacitive current, the controller is configured to reduce the distortion of the current flowing through the inductor by controlling each of the first switching element, the second switching element, the third switching element, and the fourth switching element in each of the first section, the second section, and the third section, such that:
in the first section, the first switching element is on, the second switching element is off, the third switching element is off, and the fourth switching element is off;
in the second section, the first switching element is off, the second switching element is off, the third switching element is off, and the fourth switching element is on; and
in the third section, the first switching element is off, the second switching element is on, the third switching element is off, and the fourth switching element is on.
20. The system of claim 11 , wherein the controller is configured to reduce the distortion of the current flowing through the inductor by deriving a q-axis current component from the current flowing through the inductor and determining whether the current at the AC zero voltage crossing point is the resistive current, the inductive current, or the capacitive current based on the q-axis current.