STEPPER MOTOR

Abstract: A stepper motor operable from an alternating-current supply, having a slip-ring rotor (1-6), the rotor winding (1-7) and the stator windings (1-5) being connected in series in a circuit including commutating switches (Q1, Q2, Q3). A multi-polar rotor may be used.

Description: The present invention relates to stepper motors. This application is divided out of European patent application 83305856.3, publication number 0106595. Stepper motors are normally operated from pulsed DC supplies. The invention, which is defined in the claims appended hereto, provides a novel form of slip-ring stepper motor operable by AC. The invention will be described with reference to the accompanying drawings, in which: Fig. 1 shows a stepper motor which may be driven by AC 1-1 Output axle. 1-2 Outer case. 1-3 Bearing. 1-4 Stator iron core. 1-5 Stator winding. 1-6 Rotor iron core. 1-7 Rotor winding. 1-8 Rotor slip ring. 1-9 Rotor brushes. 1-10 The insulating holder of rotor slip ring. Fig. 2 shows the series connection diagram between the stator and rotor windings of motor in Fig. 1 and the control switch. Fig. 3 shows the truth table of the motor operation in Fig. 1. Fig. 4 shows a different embodiment. 4-1 Output axle. 4-2 Input slip ring of rotor. 4-3 Input brush of rotor. 4-4 Brush holder. 4-5 The tooth-shaped iron core of rotor. 4-6 Rotor winding. Figs. 5 and 6 shows the circuit diagram and truth table of the embodiment of Fig. 4. Figs. 7 and 8 are alternative circuits for use with this embodi­ ment. The motor of Fig. 1 is an AC and DC series repulsion stepper motor in which the polarity relations of AC or DC power applied to stator (1-4) and rotor )1-6) generate a servo-step function. The major difference between the design in this invention and the conventional DC stepper motor is that the exciting AC or DC power of the rotor (1-6) in this invention is delivered through the slip ring (1-8), and the rotor exciting winding is connected with the stator winding (1-5) in series (shown in Fig. 2 through the step-drive polarity commutation switch. Thus, the polarity relation of the stator and the rotor connected in series may be varied together with the power supply without affecting the attraction effect between poles. Moreover, the polarity relation may be varied by sequentially commutating the stator winding (1-5) and by applying AC or DC power through the polarity sequence commutation switch connected in series between the stator and the rotor. The truth table of this commutation is shown in Fig. 3. Further, the use of said repulsion stepper motor may include the known multi-stage and over-lapped type. Figs. 4 to 8, show another embodiment and control circuits for it. A motor according to the invention thus comprises an AC stepper driving motor structure, which comprises; 1) a field having a selected number of poles, and having one or more than one set of excitation windings; 2) a rotor having a selected number of poles, and having one or more than one set of windings connected to the slip ring of the rotor; 3) the related mechanical structure and brushes; 4) the polarity switching means, which may be an electro­ mechanical means, a solid state electronic switch element such as Triac, or SCR and so on; and the stator winding and rotor winding of said AC stepper driving motor may be connected in series or parallel and the number of ples between the stator and the rotor may be the same or may not; and the polarity switching means may sequentially change the opposite polarities of the rotor and stator; and the operation course of said AC stepper driving motor is to have the field becoming an un-balance state by means of switching the polarity switch for changing polarity so as to cause the rotor to rotate to a balanced point.

Claims: 1. A stepper motor operable from an alternating-current source and comprising a slip-ring rotor (1-6) and a stator (1-4), the windings (1-5) of each pair of opposite poles of the stator being connected in series with each other and with a switch (Q1, Q2, Q3), the circuit branches containing the windings with their switches being connected in parallel with one another and in series with the rotor winding (1-7). 2. A stepper motor according to Claim 1, in which the rotor has one pair of poles and switching means (Q4, Q5, Q6, Q7) are provided for reversing the polarity of the rotor winding. 3. A stepper motor according to Claim 1, in which the rotor is multipolar, having a number of poles different from that of the stator.

Inventors: YANG, TAI-HER
Applicants: YANG, TAI-HER
Application year: 1983
Main classification: H02P8
IPC codes: B23Q3, H02K29, F16H19, H02K49, H02K25, H02K33, H02K26, H02K3, H02K37, H02K23, H02P8, B23Q5, B23Q1, H02K7, B23Q11, B23P21