Power transmission control device, power transmission device, electronic instrument, and non-contact power transmission system

• US 8,060,011 B2
• Filed: 02/20/2008
• Issued: 11/15/2011
• Est. Priority Date: 02/20/2007
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Jin, Mikimoto
• Primary Examiner(s): Phu; Sanh D
• Application Number:
  US12/071,371
• Publication Number:
  US 20080197713A1
• Time in Patent Office: 1,364 Days
• Field of Search: 455/127.1, 455/41.1, 455/41.2, 455/573, 455/572, 320/108
• US Class Current: 455/41.1
• CPC Class Codes: H02J 50/10 using inductive coupling
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/60 responsive to the presence of foreign objects, e.g. detection of living beings
• CPC Class Codes: H02J 50/70 involving the reduction of electric, magnetic or electromagnetic leakage fields
• CPC Class Codes: H02J 50/80 involving the exchange of data, concerning supply or distribution of electric power, between transmitting devices and receiving devices
• CPC Class Codes: H02J 50/90 involving detection or optimisation of position, e.g. alignment
• CPC Class Codes: H02J 7/00045 Authentication, i.e. circuits for checking compatibility between one component, e.g. a battery or a battery charger, and another component, e.g. a power source
• CPC Class Codes: H02J 7/02 for charging batteries from ac mains by converters

Abstract

A power transmission control device provided in a power transmission device of a non-contact power transmission system includes a drive clock signal generation circuit that generates a drive clock signal that specifies a drive frequency of a primary coil, a driver control circuit that generates a driver control signal based on the drive clock signal and outputs the driver control signal to a transmission driver, a waveform adjusting circuit that outputs a waveform adjusting signal of an induced voltage signal of the primary coil, a pulse width detection circuit that receives the waveform adjusting signal and the drive clock signal and detects pulse width information relating to the waveform adjusting signal, and a control circuit that detects a change in secondary-side load based on the detected pulse width information.

Claims

1. A power transmission control device provided in a power transmission device of a non-contact power transmission system, the non-contact power transmission system transmitting power from the power transmission device to a power reception device by electromagnetically coupling a primary coil and a secondary coil to transmit the power to a load of the power reception device, the power transmission control device comprising:

a drive clock signal generation circuit that generates a drive clock signal that specifies a drive frequency of the primary coil;

a driver control circuit that generates a driver control signal based on the drive clock signal, and outputs the driver control signal to a transmission driver that drives the primary coil;

a waveform adjusting circuit that adjusts a waveform of an induced voltage signal of the primary coil and outputs a waveform adjusting signal;

a pulse width detection circuit that receives the waveform adjusting signal and the drive clock signal and detects pulse width information relating to the waveform adjusting signal; and

a control circuit that detects a change of secondary-side load based on the pulse width information that has been detected.

2. The power transmission control device as defined in claim 1,

the control circuit detecting data that has been transmitted from the power reception device by means of load modulation based on the detected pulse width information that has been detected.

3. The power transmission control device as defined in claim 1,

the pulse width detection circuit detecting the pulse width information by measuring a pulse width period, the pulse width period being a period from a first point when the drive clock signal changes from an inactive voltage level to an active voltage level to a second point when the waveform adjusting signal changes from an active voltage level to an inactive voltage level.

4. The power transmission control device as defined in claim 3,

the pulse width detection circuit including a counter that increments or decrements a count value during the pulse width period and measures the pulse width period based on the count value.

5. The power transmission control device as defined in claim 4,

the pulse width detection circuit including an enable signal generation circuit that receives the waveform adjusting signal and the drive clock signal and generates an enable signal that becomes active in the pulse width period;

and

the counter incrementing or decrementing the count value when the enable signal is active.

6. The power transmission control device as defined in claim 5,

the enable signal generation circuit including a flip-flop circuit that is reset or set when the waveform adjusting signal is active, the drive clock signal being input to a clock signal terminal of the flip-flop circuit and a high-potential-side power supply voltage or a low-potential-side power supply voltage being input to a data terminal of the flip-flop circuit.

7. The power transmission control device as defined in claim 6,

the waveform adjusting circuit including a comparator, the induced voltage signal of the primary coil being input to a non-inverting input terminal of the comparator and a given set voltage being input to an inverting input terminal of the comparator.

8. The power transmission control device as defined in claim 4,

the pulse width detection circuit including:

a count value holding circuit that holds the count value from the counter; and

an output circuit that compares a first count value with a second count value, the first count value being the count value that has been currently held by the count value holding circuit, the second count value being the count value that has been previously held by the count value holding circuit, and outputs a larger count value among the first count value and the second count value.

9. The power transmission control device as defined in claim 4,

the pulse width detection circuit including:

a count value holding circuit that holds the count value from the counter; and

an output circuit that outputs an average value of a plurality of count values that have been held by the count value holding circuit.

10. The power transmission control device as defined in claim 1,

the power transmission control device further including:

an amplitude detection circuit that detects amplitude information relating to the induced voltage signal of the primary coil;

an A/D conversion circuit that performs A/D conversion of the amplitude information;

a first latch circuit that latches data from the A/D conversion circuit; and

a second latch circuit that latches data from the pulse width detection circuit,

the second latch circuit latching the data from the pulse width detection circuit at a timing synchronized with a latch timing of the first latch circuit.

11. A power transmission device comprising:

the power transmission control device as defined in claim 1; and

a power transmission section that generates an alternating voltage and supplies the alternating voltage to the primary coil.

12. An electronic instrument comprising the power transmission device as defined in claim 11.

13. A non-contact power transmission system comprising a power transmission device and a power reception device, the non-contact power transmission system transmitting power from the power transmission device to the power reception device by electromagnetically coupling a primary coil and a secondary coil to transmit the power to a load of the power reception device, the power reception device including:

a power reception section that converts an induced voltage in the secondary coil into a direct voltage; and

a load modulation section that variably changes a load depending on transmission data when the power reception device transmits data to the power transmission device; and

the power transmission device including;

a drive clock signal generation circuit that generates a drive clock signal that specifies a drive frequency of the primary coil;

a driver control circuit that generates a driver control signal based on the drive clock signal, and outputs the driver control signal to a transmission driver that drives the primary coil;

a waveform adjusting circuit that adjusts a waveform of an induced voltage signal of the primary coil and outputs a waveform adjusting signal;

a pulse width detection circuit that receives the waveform adjusting signal and the drive clock signal and detects pulse width information relating to the waveform adjusting signal; and

a control circuit that detects a change in secondary-side load based on the pulse width information that has been detected.

14. A power transmission control device provided in a power transmission device of a non-contact power transmission system, the non-contact power transmission system transmitting power from the power transmission device to a power reception device by electromagnetically coupling a primary coil and a secondary coil to transmit the power to a load of the power reception device, the power transmission control device comprising:

a drive clock signal generation circuit that generates a drive clock signal that specifies a drive frequency of the primary coil;

a driver control circuit that generates a driver control signal based on the drive clock signal, and outputs the driver control signal to a transmission driver that drives the primary coil;

a waveform adjusting circuit that adjusts a waveform of an induced voltage signal of the primary coil and outputs a waveform adjusting signal;

a pulse width detection circuit that receives the waveform adjusting signal and the drive clock signal and detects pulse width information of the waveform adjusting signal; and

a control circuit that controls the power transmission control device based on the pulse width information that has been detected.

15. A power transmission device comprising:

the power transmission control device as defined in claim 14; and

a power transmission section that generates an alternating voltage and supplies the alternating voltage to the primary coil.

16. An electronic instrument comprising the power transmission device as defined in claim 15.

17. A non-contact power transmission system comprising a power transmission device and a power reception device, the non-contact power transmission system transmitting power from the power transmission device to the power reception device by electromagnetically coupling a primary coil and a secondary coil to transmit the power to a load of the power reception device,

the power transmission device being the power transmission device as defined in claim 15.