Electricity: motive power systems – Open-loop stepping motor control systems
Patent
1986-09-08
1988-03-15
Shoop, Jr., William M.
Electricity: motive power systems
Open-loop stepping motor control systems
318685, 318701, H02P 800
Patent
active
047315709
DESCRIPTION:
BRIEF SUMMARY
DESCRIPTION
1. Technical Field
The present invention relates to electrical drive circuits for motors and, more particularly, to a drive circuit for a variable-speed switched reluctance motor having a bifilar winding, that is to say main and auxiliary windings integrally wound on the motor.
2. Background Art
In recent years considerable interest has been shown in the use of switched-reluctance motor drives as a replacement for conventional induction motor drives. The former have been shown to be able to achieve unusually good combinations of high power output and system efficiency while having costs considerably below those of AC-motor systems. Variable-speed switched reluctance machines are also often able to provide a range and quality of control usually only associated with the best DC-motor systems, while providing a range of substantial operational advantages in terms of reliability and robustness.
Various drive circuits are known and, in particular, drive circuits using thyristor switches have been utilized to provide the desired commutation control of the individual phases of the motor. Each phase has its own respective drive circuit and these are identical with one another. Conventional circuits utilize a commutation capacitor which is initially charged to a supply voltage by the firing of a first thyristor switch which is then switched off, a second thyristor switch being closed to allow current produced by the capacitor to flow through the load winding of the motor. As there are advantages in using bifilar wound motors, modified circuits have been utilized, but those studied have suffered from various disadvantages.
The present invention is directed to overcoming one or more of the problems as set forth above.
DISCLOSURE OF THE INVENTION
According to the present invention, an electrical drive circuit for a variable-speed switched reluctance motor connectable to a DC power source is provided. The motor has a bifilar winding having a main winding and an auxiliary winding. The drive circuit includes first and second voltage/current lines for connection to the DC power source, one end of the main winding being connected to the first voltage/current line. A resonant reversal inductor is also included.
First, second and third thyristor switches each have a respective firing circuit for firing the thyristor switches to conduction. The first thyristor switch is connected between the second end of the main winding and the second voltage/current line. The second and third thyristor switches are connected in series with the inductor between the second end of the main winding and the second voltage/current line, in parallel with the first thyristor switch. A commutation/snubber capacitor device is connected in parallel with the third thyristor switch between the second thyristor switch and the second voltage/current line. Means are included for sensing the direction of current flow through the commutation/snubber capacitor device, thereby to sense current flow through either the second or the third thyristor switches.
Finally, control means are provided for preventing the first and third thyristor switches from conducting when the second thyristor switch is conducting and to prevent the first and second thyristor switches from conducting when the third thyristor switch is conducting, the control means being connected to the sensing means and to the firing circuits.
BRIEF DESCRIPTION OF THE DRAWINGS
One example of one phase of a drive circuit according to the present invention will now be described with reference to the accompanying drawings in which:
FIG. 1 shows the basic arrangement of a drive circuit for one phase (in a 3-phase machine there will be two further identical circuits);
FIG. 2 illustrates a first thyristor firing circuit;
FIG. 3 illustrates a second thyristor firing circuit;
FIG. 4 illustrates a current sensing circuit;
FIG. 5 illustrates a control means for the thyristor firing circuits; and
FIGS. 6 and 7 are timing diagrams for various signals of the circuit.
BEST MODE FOR CARRYING O
REFERENCES:
patent: 4387326 (1983-06-01), Ray et al.
patent: 4500824 (1985-02-01), Miller
Bergmann Saul M.
Caterpillar Inc.
Noe Stephen L.
Shoop Jr. William M.
LandOfFree
Electrical drive circuit for a variable-speed switched reluctanc does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electrical drive circuit for a variable-speed switched reluctanc, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electrical drive circuit for a variable-speed switched reluctanc will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1928120