JPS62100198A - Controller for stepping motor of battery power supply - Google Patents

Abstract

PURPOSE:To enable revolution at high speed, and to obtain a battery effective- utilizing voltage range wider than conventional devices by changing the oscillating frequency of pulses in response to an operating voltage drop with time of a battery. CONSTITUTION:Pulses generated from an oscillator OSC are applied to a driver 2 through an AND gate 3, thus driving a stepping motor 1. A photo-coupler 6 is formed by an LED4 and a CDS5, the resistance value of the CDS5 is changed in response to the voltage fluctuation of a battery E, and the oscillating frequency of the oscillator OSC is altered. When the voltage of the battery is high, the oscillating frequency is increased, and the motor is turned at high speed. Torque hardly lowers because of high voltage at that time. When the voltage of the battery drops, the oscillating frequency is decreased, and the lowering of torque is reduced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a stepping motor control 1+ device suitable for use in small mobile equipment whose power source is a battery and whose power source is a microcomputer-controlled stepping motor. Regarding.

[Prior Art] This type of conventional stepping motor control device that uses a microcomputer generates pulses and also uses a dedicated LSI to control the number of rising and falling pulses, the maximum pulse frequency, and the target position. The total number of pulses is stored in advance, and by counting the pulses, the stepping motor is controlled by issuing commands to start rotation, continue rotation, and stop rotation. When a battery is used as a power source in such a control device, due to the nature of the battery, the voltage deteriorates and fluctuates greatly during use, so the pulse is applied so that the stepping motor's 1 to 1 kW does not drop even if the terminal voltage of the battery drops slightly. It was necessary to set the oscillation frequency of the stepping motor to a low value so that even a small voltage drop would not cause the stepping motor to stop rotating. For this reason, it has been difficult for battery-operated devices to rotate stepping motors at high speeds.

[Problem to be Solved by the Invention 1] However, the present invention provides a battery-powered stepping motor control device that allows the stepping motor to rotate at a high speed, which has been difficult in the past, and provides a wider voltage range for effective use of batteries than before. It provides:

[Means for Solving the Problems] A battery-powered stepping motor control t11 device of the present invention will be described with reference to FIGS. 1 to 4.

Battery powered stepping motor control device of the present invention (A
)teeth. A driver (2) connected to the stepping motor (1), an oscillator (O20) that generates pulses, and an oscillator (O20) interposed between the driver (2) and the oscillator (O20).
) and an AND gate (3) that transmits and blocks the pulses sent from the driver (2), an LED (4), and C; O8.
(5) forms a photocoupler (6), and a capacitor (6) is inserted to change the resistance value of the CDS (5) in response to changes in the voltage of the battery (E) and change the oscillation frequency of the oscillator (08G). A control unit (A) that gradually flows and cuts off current to the LED (4) with a time constant of CI>(C2) and a resistor (R1), and counts pulses output from the AND gate (3). A counter (8), a command to determine the rotation direction of the stepping motor (1), a command to open and close the AND gate (3), a command to conduct/cut off current to the LED (4), and a control section. (7) and a microcomputer (10) which issues a command to completely discharge the interposed capacitors (C1) and (C2) and return them to a chargeable state in accordance with a program.

The driver (2) is connected to the No. 1 boat (1) of the output boat (9) to receive a rotation direction command. The oscillator (O20) is a self-running multivibrator constructed from a general-purpose timer IC (not shown).

The AND gate (3) connects the output of the oscillator (O20) to one input side, connects the second port (i) of the output port (9) to the remaining one, and connects the output side to the driver (2). and the counter (8).

The control unit (7) controls the oscillation frequency [
The resistor (RA') (R11) that determines the
R1) and the capacitor (C1) form a coupler (6), and connect both ends of the capacitor (C2) between the resistor (R1) and the LED (4) and between the LED (4) and the capacitor (C1). On one end of (C2), there is a resistor (R3) connected to the 4th boat (■) of the output port (9).
Connect the collector of 1-transistor (Tr2) with the base connected through and the emitter grounded, and the remaining narrow end is connected to the No. 3 port (III) of the output boat (9) through the resistor (R2). This is done by connecting the collector of a transistor (Trl) whose base is connected and whose emitter is grounded.

In FIG. 1, (R4) and (R5) are voltage dividing resistors.

(However, if the voltage of the battery (E) is about 6 to 12 V rg, the voltage dividing resistor (R4') (R5) may be omitted and the resistor <R1) and the battery (E) may be directly connected).

In addition, the photocoupler (6) has a CDS (5) of approximately 700 Ω when a current of 15 mA flows through the LED (4).
) when no current flows through it, the resistance value is almost at the maximum value of 'M'.

The counter (8) is a CPtJ bus directly connected counter, and is a down counter in which the counter value can be freely read and written.

Microcomputer (10) is a well-known computer,
Basically, it consists of CPU, RAM, and ROMJI.

A program to control the CPU is written in the ROM, and the CPU takes in the pulse number data written in the counter (8) and performs performance processing according to the program while exchanging data with the RAM. , and outputs the processed data to the output boat (9) as necessary.

The programs written in the ROM are shown in flowcharts as shown in FIGS. 3 and 4. Further, when the apparatus of the present invention is operated according to the program shown in FIG. 4, the relationship between pulse frequency and time is as shown in FIG. 2. The solid line in FIG. 2 represents the change when the voltage of the battery (E) is high, and the dotted line represents the change when the voltage of the battery (E) is decreased.

[Function] Here, the function of the device of the present invention will be explained based on FIGS. 1 to 4.

First, the output boat (9) is initialized. (See FIG. 3) That is, the second output port (II) is set to OV (hereinafter referred to as below), the AND gate (3) is closed, and the operation of the driver (2) and counter (8) is stopped. Next, the third output port is set to L to turn off the transistor (Trl). Next, the fourth output port (rV) is set to 5V (hereinafter referred to as 1), and the capacitors (C1) and (C2) are completely discharged to complete the initialization.

Next, the total number of pulses up to the target position is written into the counter (8) from the ROM or RAM depending on the purpose. (Those with fixed specifications that can be stored in the ROM are written to the ROM, and items that change depending on the calculation results are written to the RAM.) Set the No. 1 output port (I) to H or L to the stepping motor ( 1), and set the fourth output port NV) to L to turn off the transistor (Tr2) and make the capacitors (C1) and (C2) ready for charging.

Next, the second output port (ff) is set to (), and the AND gate (3) is opened to apply the pulse of the oscillation frequency determined by the formula described above to the clock input of the driver (2) and the input of the counter (8). The stepping motor (1) now starts rotating (state of ■ in Figure 2).The frequency at this time is L.
Since no current flows through ED (4), the frequency is the lowest. (However, this value should be within the self-starting frequency range in which the stepping motor (1) does not cause step-out).

Also, when the third output port (I[[) is set to H and the transistor (Trl) is turned on, current gradually flows to the LED (4) with the time constant of the resistor (R1) and capacitor (C2). Therefore, the resistance value of CDS (5) also gradually decreases, and the oscillation frequency increases (state 2 in FIG. 2). The capacitor (C1) then enters a discharge state. (Capacitor (
C2) is charged).

As shown by the solid line in Figure 2, when the terminal voltage of the battery is high, the divided voltage of the voltage dividing resistor (R4) (R5') is also high < LE.
As the current in D (4) increases, the oscillation frequency increases and the stepping motor (1) rotates at a high speed, and when it decreases, the oscillation frequency decreases as shown by the dotted line and the stepping motor (1) rotates at a low speed. The microcomputer (10) reads the latest counter value from the counter (8), subtracts it from the initially set number of pulses, and determines whether the remaining number of pulses is below a certain level. The counter value can be read and subtracted repeatedly (state ◯ in Fig. 2). In the case of Yes, the third output port 1~(I[[) is set to L and the transistor (Tr+)
Turn off. At this time, the capacitor (C1) was completely discharged, so the current of the LED (4) did not suddenly become zero, but gradually with the time constant of the resistor (R1) and the capacitor (C1) until the capacitor (C1) was charged. As the current decreases, the oscillation frequency also gradually decreases (as shown by the shape c in Figure 2).
,). When fully charged, the current of the LED (4) also becomes zero, and the oscillation frequency at this time becomes the same lowest as at the beginning.

Furthermore, the microcomputer (10) has a counter (8
) and subtract it from the initially set number of pulses to determine whether the remaining number of pulses is zero. If No, repeat reading and subtracting the counter value again (■ in Figure 2). condition). If Yes, set the No. 2 output boat (IF) to L, close the AND gate (3), stop the rotation of the stepping motor (1), and then set the No. 4 output boat (rV) to H. For this operation, capacitors (C1) and (C2) are completely discharged.

[Effects] As described above, in the present invention, the oscillation frequency of the pulse changes in response to the voltage drop over time as the battery operates. High-speed rotation of the stepping motor is possible. or. As a characteristic of a stepping motor, when the rotation speed increases, the coil current decreases and the torque decreases, and conversely, when the rotation speed decreases, the coil current increases and the torque increases.
This is described in 11 of the present invention. II Let's look at the case of control using Ill purchasing. The fact that the stepping motor is rotating at high speed means that the voltage of the battery is high, and the coil current increases as the voltage increases, so the drop in coil current is small.

Therefore, the decrease in torque is also small. On the other hand, even if the battery voltage gradually decreases, the oscillation frequency decreases, the rotational speed decreases, and the coil current increases, so even with a considerable voltage drop, sufficient coil current can flow, and the torque decreases little. It spreads. Therefore, it is advantageous in terms of efficiency and economy, and has excellent effects such as being able to obtain a wide range of effective use of batteries.

4. Brief explanation of the drawings Fig. 1 is a block diagram of the device of the present invention, Fig. 2 is a diagram of the relationship between pulse frequency and time when the device of the present invention is operated, and Figs. 3 to 4 are each a diagram of the device of the present invention. This is a flowchart of the program used in .

A...Battery powered stepping motor control device oS
C...Oscillator RA, RB...Resistance R1
, R2, R3... Resistors R4, R5... Voltage dividing resistors Go, CI, C2... Capacitors Tr1. Tr2
...1~Rangister■...1st boat ■...2nd boat■...
・No.3 boat ■・・・No.4 ported・Stepping motor

Claims (1)

[Claims] 1. A driver connected to a stepping motor, an oscillator that generates pulses, an AND gate that is interposed between the driver and the oscillator and transmits and blocks pulses sent from the oscillator to the driver, and a battery operating voltage over time. A control section configured to gradually conduct/cut off the current by interposing a capacitor to change the oscillation frequency of the oscillator in response to the drop, and a counter for counting pulses output from the AND gate. , a command to open the AND gate and start rotation of the stepping motor, a command to flow current to the control section, and subtracting the latest pulse count value from a preset value to a value below a certain value. A command to stop the current in the control section when the temperature reaches zero, and a command to close the AND gate when the latest pulse count value is subtracted from a preset value and becomes 0. A battery-powered stepping motor control device comprising a microcomputer that sequentially issues commands to completely discharge the interposed capacitor and return it to a chargeable state.