Converter for converting code-modulated power with conversion code, power transmission system, and controller

1. A converter comprising:

a terminal that receives code-modulated power into which first alternating-current power has been code-modulated with a modulation code, the first alternating-current power having a first frequency; and

a circuit that converts the code-modulated power with a conversion code to generate second alternating-current power having a second frequency lower than the first frequency,

wherein the conversion code includes:

a first partial sequence, of which bit values are respectively the same as corresponding bit values of the modulation code;

a second partial sequence, of which bit values are respectively the same as values obtained by inverting corresponding bit values of the modulation code;

a third partial sequence, of which bit values are respectively the same as values obtained by inverting corresponding bit values of the modulation code; and

a fourth partial sequence, of which bit values are respectively the same as corresponding bit values of the modulation code, and

wherein the circuit converts the code-modulated power into the second alternating-current power by performing code demodulation that includes:

in a first period, code-demodulating the code-modulated power with the first partial sequence to generate a first positive current;

in a second period, invertedly code-demodulating the code-modulated power with the second partial sequence to generate a second positive current;

in a third period, invertedly code-demodulating the code-modulated power with the third partial sequence to generate a first negative current; and

in a fourth period, code-demodulating the code-modulated power with the fourth partial sequence to generate a second negative current.

2. The converter according to claim 1 ,

wherein each cycle of the first partial sequence, the second partial sequence, the third partial sequence, and the fourth partial sequence is one-fourth or less of a cycle of the second alternating-current power.

3. The converter according to claim 1 ,

wherein each of the first partial sequence, the second partial sequence, the third partial sequence, and the fourth partial sequence is an orthogonal code sequence.

4. The converter according to claim 3 ,

the orthogonal code sequence is an orthogonal Gold sequence or an orthogonal m-sequence.

5. The converter according to claim 1 ,

wherein the second frequency of the second alternating-current power is one-Nth of the first frequency of the first alternating-current power, where N is an integer greater than or equal to 2.

6. The converter according to claim 5 ,

wherein the conversion code includes 2N partial sequences including the first partial sequence, the second partial sequence, the third partial sequence, and the fourth partial sequence, and

the 2N partial sequences have the same code length.

7. The converter according to claim 1 ,

wherein the circuit comprises a plurality of switches.

8. The converter according to claim 7 , further comprising:

a control circuit that generates control signals for turning on and off the switches,

wherein the circuit converts the code-modulated power in accordance with the control signals.

9. The converter according to claim 8 , further comprising:

a communication circuit that receives, from a controller, an instruction signal that includes timing information indicating a timing at which the code-modulated power is to be converted and code information regarding the conversion code, and

the control circuit generates the control signals in accordance with the instruction signal.

10. The converter according to claim 1 ,

wherein the circuit comprises an H-bridge circuit in which four bidirectional switch circuits are connected in a full-bridge configuration.

11. A power transmission system comprising:

the converter according to claim 1 ; and

a code modulator that code-modulates the first alternating-current power with the modulation code to generate the code-modulated power.

12. The converter according to claim 1 ,

wherein the code-modulated power is power of which current direction and/or voltage polarity changes at periods each corresponding to an integer multiple of a unit period.

13. The converter according to claim 1 ,

wherein the first partial sequence, the second partial sequence, the third partial sequence, and the fourth partial sequence have the same code length.

14. The converter according to claim 1 ,

wherein each cycle of the first partial sequence, the second partial sequence, the third partial sequence, and the fourth partial sequence is equal to a half cycle of the first alternating-current power.

15. The converter according to claim 1 ,

wherein the third partial sequence is the same sequence as the second partial sequence, and the fourth partial sequence is the same sequence as the first partial sequence.

16. The converter according to claim 1 ,

wherein the second positive current is the same current as the first positive current, and the second negative current is the same current as the first negative current.

17. The power transmission system according to claim 11 , further comprising:

a controller including a processor and a communication circuit; and

a transmission path through which the code modulator and the converter are connected to each other,

wherein the processor:

generates a first instruction signal for code-modulating the first alternating-current power with the modulation code to generate the code-modulated power;

transmits the first instruction signal to the code modulator via the communication circuit;

generates a second instruction signal for converting the code-modulated power with the conversion code to generate the second alternating-current power; and

transmits the second instruction signal to the converter via the communication circuit.