Position sensorless control method for switched reluctance generator

Abstract

A control method for a switched reluctance generator employing dual switched-mode power converters does not require a position sensor. In the excitation stage, the upper tube and lower tube of the main switch of a phase in the power converter are switched on, and the phase current is detected. When the phase current rises to a preset threshold, the upper tube or lower tube of the main switch of the phase is switched off, changing the phase of the switched reluctance generator into a zero voltage natural freewheeling state. When the phase current drops to the valley value, the rotor position is the end position of maximum phase inductance of the phase. This rotor position is used as the switch-off position of the main switch of the phase of the switched reluctance generator, and the upper tube and lower tube for the main switch of the phase are switched off.

Claims

1. A control method for a switched reluctance generator without a position sensor, and having a excitation power supply, windings of a switched reluctance generator, and a power converter composed of main switch and diodes with an upper tube S1 and a lower tube S2 in the power converter of the main switch of a phase in an ON state in the excitation stage, comprising the steps of: setting a threshold for the winding current of the phase, and detecting the winding current i of the phase; switching off either the upper tube S1 or the lower tube S2 in the power converter of the main switch of the phase when the winding current i of the phase rises to a preset threshold, so that the winding of the phase of the switched reluctance generator changes into a zero voltage natural freewheeling state and the winding current i of the phase begins to drop; the rotor position of the switched reluctance generator is the end position b of maximum phase inductance of the phase when the winding current i of the phase drops to a valley value, acquiring the end position b of maximum phase inductance of the phase; and switching off the upper tube S1 and lower tube S2 of the main switch in the power converter.

2. The method of claim 1 wherein said switching off step switches off the lower tube S2.

3. The method of claim 1 wherein said switching off step switches off the upper tube S1.

4. A control method for a switched reluctance generator without a position sensor, and having a excitation power supply, windings of a switched reluctance generator, and a power converter composed of main switch and diodes with an upper tube S1 and a lower tube S2 in the power converter of the main switch of a phase in an ON state in the excitation stage, comprising the steps of: setting a threshold for the winding current of the phase, and detecting the winding current i of the phase; switching off either the upper tube S1 or the lower tube S2 in the power converter of the main switch of the phase when the winding current i of the phase rises to a preset threshold, so that the winding of the phase of the switched reluctance generator changes into a zero voltage natural freewheeling state and the winding current i of the phase begins to drop; and acquiring the end position b of maximum phase inductance of the phase when the rotor position of the switched reluctance generator is an end position b of maximum phase inductance of the phase when the winding current i of the phase drops to a valley value.

5. The control method of claim 4 further comprising the steps of: taking the end position b of maximum phase inductance of the phase as the acquired switch-off position .sub.2 of the main switch of the phase in the power converter of switched reluctance generator; and switching off the upper tube S1 and lower tube S2 of the main switch in the power converter.

6. A method of controlling a switched reluctance generator without a position sensor, and having a excitation power supply, windings of a switched reluctance generator, and a power converter composed of main switch and diodes with an upper tube S1 and a lower tube S2 in the power converter of the main switch of a phase movable between an ON state and an OFF state, comprising the steps of: placing the upper tube S1 and the lower tube S2 into the OFF state in the excitation stage; setting a threshold for the winding current of the phase; detecting the winding current i of the phase; when the winding current i of the phase rises to a preset threshold, switching either the upper tube S1 or the lower tube S2 into the OFF state so that the winding of the phase of the switched reluctance generator changes into a zero voltage natural freewheeling state and the winding current i of the phase begins to drop; and acquiring the end position b of maximum phase inductance of the phase when the rotor position of the switched reluctance generator is an end position b of maximum phase inductance of the phase when the winding current i of the phase drops to a valley value.

7. The method of claim 6 further comprising the steps of: taking the end position b of maximum phase inductance of the phase as the acquired switch-off position .sub.2 of the main switch of the phase in the power converter of switched reluctance generator; and switching off the upper tube S1 and lower tube S2 of the main switch in the power converter.

8. The method of claim 7 wherein said switching step places only the upper tube S1 into the OFF state.

9. The method of claim 7 wherein said switching step places only the lower tube S2 into the OFF state.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic diagram of the current path of a phase in the switched reluctance generator system in the present invention after the phase changes into excitation state;

(2) FIG. 2 is a schematic diagram of current path of a phase in the switched reluctance generator system in the present invention after the upper tube S1 of the main switch of the phase is switched off and the phase changes into zero voltage natural freewheeling state;

(3) FIG. 3 is a schematic diagram of the characteristics of phase inductance L and phase current i in the present invention; and

(4) FIG. 4 is a schematic diagram of current path of a phase in the switched reluctance generator system in the present invention after the lower tube S2 of the main switch of the phase is switched off and the phase changes into zero voltage natural freewheeling state.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(5) Hereunder the present invention will be detailed in embodiments with reference to the accompanying drawings:

(6) Embodiment 1 . A switched reluctance generator system that employs dual switched-mode power converters for each phase

(7) The system employs excitation power supply, windings of a switched reluctance generator, and a power converter composed of main switch and diodes, wherein, in the excitation stage, the upper tube S1 and lower tube S2 of the main switch of a phase in the power converter are switched on, setting a threshold for the winding current of the phase, and detecting the phase current i; the path of phase current i is shown in FIG. 1.

(8) When the winding current i of the phase rises to the preset threshold, the upper tube S1 of the main switch of the phase in the power converter is switched off, and the phase in the switched reluctance generator changes into zero voltage natural freewheeling state, and the phase current i begins to drop; the path of phase current i is shown in FIG. 2; the characteristics of phase inductance L and phase current i are shown in FIG. 3.

(9) When the winding current i of the phase drops to the valley value, the rotor position of the switched reluctance generator is the end position b of maximum phase inductance of the phase; acquiring the end position b of maximum phase inductance of the phase, directly taking the acquired start position b as the switch-off position .sub.2 of the main switch of the phase in the power converter of switched reluctance generator, and switching off the upper tube S1 and lower tube S2 of the main switch in the power converter, as shown in FIG. 3.

(10) Embodiment 2. A switched reluctance generator system that employs dual switched-mode power converters for each phase

(11) The system employs excitation power supply, windings of a switched reluctance generator, and a power converter composed of main switch and diodes, wherein, in the excitation stage, the upper tube S1 and lower tube S2 of the main switch of a phase in the power converter are switched on, a threshold is set for the winding current of the phase, and the phase current i is detected; the path of phase current i is shown in FIG. 1.

(12) When the winding current i of the phase rises to the preset threshold, the lower tube S2 of the main switch of the phase in the power converter is switched off, and the phase of the switched reluctance generator changes into zero voltage natural freewheeling state, and the phase current i begins to drop; the path of phase current i is shown in FIG. 4; the characteristics of phase inductance L and phase current i are shown in FIG. 3.

(13) When the winding current i of the phase drops to the valley value, the rotor position of the switched reluctance generator is the end position b of maximum phase inductance of the phase; acquiring the end position b of maximum phase inductance of the phase, and directly taking the acquired start position b as the switch-off position .sub.2 of the main switch of the phase in the power converter of switched reluctance generator, and the upper tube S1 and lower tube S2 of the main switch in the power converter are switched off, as shown in FIG. 3.

(14) It will be understood that changes in the details, materials, steps and arrangements of parts which have been described and illustrated to explain the nature of the invention will occur to and may be made by those skilled in the art upon a reading of this disclosure within the principles and scope of the invention. The foregoing description illustrates the preferred embodiments of the invention; however, concepts, as based upon the description, may be employed in other embodiments without departing from the scope of the invention. The invention is not otherwise limited, except for the recitation of the claims set forth below.