ENERGY CONVERTER AND ELECTROMECHANICAL APPARATUS

• US 20100225261A1
• Filed: 02/08/2010
• Published: 09/09/2010
• Est. Priority Date: 03/05/2009
• Status: Active Grant

• Current Assignee: Godo Kaisha IP Bridge 1 (IP Bridge, Inc.)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: NAKAMURA, Kazuyoshi, TAKEUCHI, Kesatoshi
• Granted Patent: US 8,258,734 B2
• Time in Patent Office: Days
• US Class Current: 318/400.290
• CPC Class Codes: H02P 25/18 with arrangements for switching the windings, e.g. with mechanical switches or relays
• CPC Class Codes: H02P 25/184 wherein the motor speed is changed by switching from a delta to a star, e.g. wye, connection of its windings, or vice versa
• CPC Class Codes: H02P 27/08 with pulse width modulation
• CPC Class Codes: H02P 6/085 in a bridge configuration

Abstract

An energy converter includes magnetic coils of N phases (N is an integer of 3 or more), and a PWM drive circuit for driving the magnetic coils of N phases, wherein the magnetic coil of each phase can be independently controlled by the PWM drive circuit.

Claims

1. An energy converter comprising:

magnetic coils of N phases (N is an integer of 3 or more); and

a PWM drive circuit for driving the magnetic coils of N phases, wherein

the magnetic coil of each phase can be independently controlled by the PWM drive circuit.

2. The energy converter according to claim 1, further comprising a switching circuit for switching between an independent connection state where the magnetic coils of N phases are disconnected so as to be independently controlled and a star connection state where the magnetic coils of N phases are star-connected.

3. The energy converter according to claim 1, wherein

the PWM drive circuit includes

an H-bridge circuit having four switches for connecting both ends of the magnetic coil of each phase with either a power supply potential or a ground potential and four protective diodes respectively connected in parallel with the four switches, and

a PWM signal generating unit that supplies a PWM signal to the four switches, and

the four switches are controlled in each PWM cycle such that a first switch disposed on the ground potential side at one end of the magnetic coil of each phase is always turned on, a second switch disposed on the power supply potential side at the other end of the magnetic coil of each phase is turned on in a period determined by the duty ratio of the PWM signal, and a third switch disposed on the power supply potential side at the one end and a fourth switch disposed on the ground potential side at the other end are turned off.

4. An electromechanical apparatus comprising:

magnetic coils of N phases (N is an integer of 3 or more);

magnets; and

a PWM drive circuit that drives the magnetic coils of N phases, wherein

the magnetic coil of each phase can be independently controlled by the PWM drive circuit.

5. The electromechanical apparatus according to claim 4, further comprising a switching circuit for switching between an independent connection state where the magnetic coils of N phases are disconnected so as to be independently controlled and a star connection state where the magnetic coils of N phases are star-connected.

6. The electromechanical apparatus according to claim 4, wherein

the PWM drive circuit includes

an H-bridge circuit having four switches for connecting both ends of the magnetic coil of each phase with either a power supply potential or a ground potential and four protective diodes respectively connected in parallel with the four switches, and

a PWM signal generating circuit that supplies a PWM signal to the four switches, and

the four switches are controlled in each PWM cycle such that a first switch disposed on the ground potential side at one end of the magnetic coil of each phase is always turned on, a second switch disposed on the power supply potential side at the other end of the magnetic coil of each phase is turned on in a period determined by the duty ratio of the PWM signal, and a third switch disposed on the power supply potential side at the one end and a fourth switch disposed on the ground potential side at the other end are turned off.

7. The electromechanical apparatus according to claim 4, wherein

the PWM drive circuit drives all the magnetic coils of N phases at a starting time and, after the starting, selects the number of phases to be driven in accordance with the magnitude of torque required for the electromechanical apparatus.

8. The electromechanical apparatus according to claim 7, further comprising a regenerator to execute regeneration by using the magnetic coil of a phase that is not driven.

9. The electromechanical apparatus according to claim 4, further comprising a control unit that controls voltage to be applied to the magnetic coil, wherein

the control unit applies voltage to the magnetic coil in an excitation interval that is symmetric about a π

/2 phase point when a position at which the polarity of a waveform of induced voltage induced in the magnetic coil due to the movement of the magnets is reversed is defined as a π

phase point, does not apply voltage to the magnetic coil in a non-excitation interval that is symmetric about the π

phase point of the waveform of the induced voltage, and makes the length of the non-excitation interval greater as the electromechanical apparatus rotates at high revolution.