JPS6043759B2 - Stepping motor drive method - Google Patents

Description

[Detailed description of the invention] The present invention relates to a stepping motor driving method.

Generally, in order to operate a stepping motor stably, it is necessary to flow a relatively large current through the windings housed in a limited volume. As a result, the internal temperature of the motor has the disadvantage that a considerable amount of power is wasted just for positioning, especially when the motor is stopped, and the internal temperature rises. For this reason, conventionally, when the motor is stopped, the winding currents of all phases are cut, and the motor shaft is fixed by a mechanical locking method, such as by engaging the detent lever with the detent cam using a plunger magnet to fix the motor shaft. However, the conventional mechanical locking method described above has drawbacks such as difficult mechanical adjustment, high cost, and long time required for restarting.

In order to eliminate the above drawbacks, the present invention performs positioning during stopping by reducing or cutting the current flowing through the winding of at least one phase selected immediately before stopping, and will be described in detail below with reference to the drawings. .

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG.
The figure is a time chart illustrating the operation of the embodiment shown in FIG. In the example of a three-phase, three-pole stepping motor shown in Figure 1, 1 is the input terminal for step pulse a, 2
is a distributor that selects and sends out three-phase drive signals by selecting two phases in different combinations from -d each time step pulse a is input from input terminal -1, and 3 and 4 are stop signals e and f, respectively. The input terminal 5a is a first gate circuit that does not pass the drive signal while the stop signal e is being input, and 5b is a first gate circuit that does not pass the drive signal while the stop signal f is being input.
a second gate circuit that does not allow the drive signal c to pass through, 6a;
6b and 6c are the windings 7a and 7b of each phase of the stepping motor in accordance with the drive signals b and c passed through the first gate circuit 5a) and the second gate circuit 5b, or the drive signal d sent directly from the distributor 2, respectively. and 7c is a driver circuit that sends excitation current g-1 to 7c. The operation of the above configuration will be explained with reference to the time chart shown in FIG. First, each time a step pulse a is input to the input terminal 1, two phases are selected from the three-phase drive signals bd from the distributor 2 in different combinations and sent out. Here, while the stop signals e and f are not input to the input terminals 3 and 4, the drive signals b and c are applied to the first gate circuit 5a and the second gate circuit 5a.
In order to pass through the gate circuit 5b, the three-phase drive signals b-d sent from the distributor 2 directly drive the driver circuits 6a,
Similarly to when 6b and 6c are driven, windings 7a and 7b
Excitation current g-1 flows through and 7c, and a stepping motor (not shown) rotates. Next, for example, if the stepping motor is to be stopped at a point where the step pulses a shown in FIG. 2 are input as Pl, P2, and P3, the input of the next step pulse is stopped. At this time, exciting currents g and h
is flowing through the windings 7a and 7c, so the windings 7a and 7c stop at a position where the electromagnetic forces are balanced. Here, a stop signal e is input to the input terminal 3 to prevent the first gate circuit 5a from passing through, thereby preventing the excitation current g from flowing through the winding 7a. Therefore, the excitation current h flows only through the winding 7c, and accordingly, the stepping motor also increases at 116
Since it rotates, stops, and is held at this position, it consumes less power and generates less heat. Next, to restart, first turn on the stop signal e. Stop the input and return to the state before the stop signal e was input. In response to this, the stepping motor also rotates 1B in the opposite direction to the above, returning to the state before stopping. After this, if the next stepping motor a is input as P4, P5, . . . P8, it will immediately start rotating. Therefore, compared to mechanical locking methods, restarting can be performed faster. In the above explanation, winding 7
Although we have explained the case where excitation currents g and h flow through windings a and 7c, when excitation current g-1 flows through windings 7b and 7c or windings 7c and 7a, a stop signal f is input to input terminal 4. Then, it will stop in the same way and be held at that position.The present invention is not limited to the above embodiments.
Of course, it can be applied to an n-phase stepping motor having two or more phases, and in this case, the gate circuit n may be added to all the phases, or as in this embodiment, the gate circuit n may be added to the n-phase stepping motor. It can be implemented in the same way even if it is added to one phase.

Further, instead of completely cutting off the excitation current of one of the selected phases as in the above embodiment, the excitation current of at least one of the selected phases may be reduced. As described above in detail, according to the present invention, the stepping motor requires less power consumption to position the stepping motor, generates less heat, is less expensive, and can be restarted at high speed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, and FIG.
The figure is a time chart for explaining the operation of the embodiment shown in FIG. 2...Distributor, 5a...First gate circuit, 5b...Second gate circuit, 6a, 6b and 6
c...driver circuit, 7a, 7b and 7c...
winding.

Claims (1)

[Claims] 1. In a stepping motor driving method in which two selected phases of windings of a plurality of phases are sequentially excited and driven, means for controlling the current flowing through the winding of one of the two selected phases is provided. and after temporarily stopping the selected two phases while keeping them simultaneously excited, reducing or cutting the current flowing through the winding of one of the selected two phases to perform positioning at the time of stopping, Further, a stepping motor driving method is characterized in that the current flowing in the one phase is returned to the state immediately before stopping and then restarted.