Contactless power transmission apparatus and adjustment method thereof
A power transmission apparatus supplies power to a power reception apparatus without contact therebetween. The power transmission apparatus includes: a power conversion unit that outputs an alternating-current voltage of a predetermined frequency; a power transmission unit that has a power transmission coil and a capacitor that is connected to the power transmission coil; a transmission line that connects the power conversion unit and the power transmission unit; and a compensator that is disposed between the power conversion unit and the transmission line. The compensator includes: an inductive reactance element that has an inductive reactance that is greater than an inductive reactance of the transmission line; and a capacitor that reduces an inductive reactance that is a sum of an inductive reactance of the transmission line and an inductive reactance of the inductive reactance element. The inductive reactance element and the capacitor are connected.
1. A power transmission apparatus that supplies power to a power reception apparatus without contact therebetween, the power transmission apparatus comprising:
a power conversion unit that outputs an alternating-current voltage of a predetermined frequency;
a power transmission unit that has a power transmission coil and a capacitor that is connected to the power transmission coil;
a transmission line that connects the power conversion unit and the power transmission unit; and
a compensator that is disposed between the power conversion unit and the transmission line, wherein
the compensator includes
an inductive reactance element that has an inductive reactance that is greater than an inductive reactance of the transmission line, and
a capacitor that reduces an inductive reactance that is a sum of an inductive reactance of the transmission line and an inductive reactance of the inductive reactance element, wherein the inductive reactance element and the capacitor of the compensator are connected.
2. The power transmission apparatus according to claim 1 , wherein:
a capacitance of the capacitor of the compensator is a capacitance that generates a capacitive reactance capable of canceling out the inductive reactance that is the sum of the inductive reactance of the transmission line and the inductive reactance of the inductive reactance element.
3. The power transmission apparatus according to claim 1 , wherein:
an inductance of the inductive reactance element and a capacitance of the capacitor of the compensator are determined based on an output voltage of the power conversion unit and an input voltage of the power transmission unit.
4. The power transmission apparatus according to claim 3 , wherein:
the inductance of the inductive reactance element and the capacitance of the capacitor of the compensator are an inductance and a capacitance at which a difference between the output voltage and the input voltage is equal to or less than a determination value.
5. The power transmission apparatus according to claim 3 , wherein:
the compensator includes
n inductive reactance elements (n being a natural number),
m capacitors (m being a natural number, where at least either of n and m is 2 or greater), and
a switch that changes a combination of the n inductive reactance elements and the m capacitors.
6. The power transmission apparatus according to claim 5 , further comprising:
a control apparatus that controls switching of the combination of the n inductive reactance elements and the m capacitors by the switch such that a voltage difference between the output voltage and the input voltage is equal to or less than a determination value.
7. The power transmission apparatus according to claim 1 , wherein:
an inductance of the inductive reactance element and a capacitance of the capacitor of the compensator are determined based on an output voltage of the power conversion unit and an output current outputted from the power conversion unit.
8. The power transmission apparatus according to claim 7 , wherein:
the inductance of the inductive reactance element and the capacitance of the capacitor of the compensator are an inductance and a capacitance at which a difference between a phase of the output voltage and a phase of the output current is equal to or less than a determination value.
9. The power transmission apparatus according to claim 7 , wherein:
the compensator includes
n inductive reactance elements (n being a natural number),
m capacitors (m being a natural number, where at least either of n and m is 2 or greater), and
a switch that changes a combination of the inductive reactance elements and the capacitors.
10. The power transmission apparatus according to claim 9 , further comprising:
a control apparatus that controls switching of the combination of the n inductive reactance elements and the m capacitors by the switch such that a difference between a phase of the output voltage and a phase of the output current is equal to or less than a determination value.
11. The power transmission apparatus according to claim 5 , wherein:
the switch is a semiconductor switch.
12. The power transmission apparatus according to claim 1 , wherein:
the inductive reactance element is a coil or a transformer.
13. The power transmission apparatus according to claim 1 , wherein:
the compensator has a noise filter for removing high-frequency noise of the power conversion unit, the noise filter including a coil; and
the coil of the noise filter is used as the inductive reactance element.
14. The power transmission apparatus according to claim 1 , wherein:
two or more power transmission units are connected to a single power conversion unit.
15. An adjustment method of a power transmission apparatus that supplies power from a power conversion unit to a power transmission unit through a transmission line, the power conversion unit outputting an alternating-current voltage, and the power transmission unit including a power transmission coil and a capacitor connected to the power transmission coil, the adjustment method comprising:
disposing, between the power conversion unit and the transmission line, a compensator that includes an inductive reactance element that has an inductive reactance that is greater than an inductive reactance of the transmission line and a capacitor;
measuring an output voltage of the power conversion unit and an input voltage of the power transmission unit; and
adjusting an inductance of the inductive reactance element and a capacitance of the capacitor of the compensator based on the output voltage and the input voltage.
16. The adjustment method for a power transmission apparatus according to claim 15 , wherein:
the inductance of the inductive reactance element and the capacitance of the capacitor of the compensator are adjusted such that a difference between the output voltage and the input voltage is equal to or less than a determination value.
17. An adjustment method for a power transmission apparatus that supplies power from a power conversion unit to a power transmission unit through a transmission line, the power conversion unit outputting an alternating-current voltage, and the power transmission unit including a power transmission coil and a capacitor connected to the power transmission coil, the adjustment method comprising:
disposing, between the power conversion unit and the transmission line, a compensator that includes an inductive reactance element that has an inductive reactance that is greater than an inductive reactance of the transmission line and a capacitor;
measuring an output voltage outputted from the power conversion unit and an output current outputted from the power conversion unit; and
adjusting an inductance of the inductive reactance element and a capacitance of the capacitor of the compensator based on the output voltage and the output current.
18. The adjustment method for a power transmission apparatus according to claim 17 , wherein:
the inductance of the inductive reactance element and the capacitance of the capacitor of the compensator are adjusted such that a difference between a phase of the output voltage and a phase of the output current is equal to or less than a determination value.