KR101778967B1

KR101778967B1 - Apparatus for driving stepper motor

Info

Publication number: KR101778967B1
Application number: KR1020110005618A
Authority: KR
Inventors: 서상욱
Original assignee: 엘지전자 주식회사
Priority date: 2011-01-19
Filing date: 2011-01-19
Publication date: 2017-09-18
Also published as: KR20120084211A

Abstract

A drive device for a step motor is disclosed. The present invention can drive a stepper motor by constituting a stepper motor drive circuit with simple elements without using an expensive drive IC. The present invention reduces the size of the entire circuit configuration and reduces the cost by driving the step motor by bipolar driving and two-phase excitation using a plurality of transistors.

Description

[0001] APPARATUS FOR DRIVING STEPPER MOTOR [0002]

The present invention relates to a drive apparatus for a step motor composed of simple elements without using a dedicated IC for driving a step motor.

Types of motors include an AC motor in which the driving power is AC, a DC motor in DC, and a step motor in which the driving signal is a clock pulse, depending on the driving method of the motor. The stepper motor drives the motor by controlling the current flow of each phase of the motor by the clock pulse. The moving angle of the stepper motor is determined by the number of clock pulses. For example, if a clock pulse is a stepper motor that rotates 180 times, then each clock pulse travels about 2 ° each time it is input.

The stepping motor driving (phase excitation) method is classified into uni-polar driving in which the direction of the current is constant and bipolar driving in which the direction of the current is reversed depending on the direction of the current. The driving method of the step motor is classified into constant voltage drive, voltage conversion drive, and constant current drive by a method of controlling excitation current. Or a 1-phase, 2-phase or 1-2-phase mixed excitation method depending on the excitation method. The one - phase excitation method is less used in efficiency and the two - phase excitation and the 1-2 phase excitation are mainstream. If a two-phase exciter is used, it rotates by a full step per unit pulse, that is, by a step angle, and when a 1-2 phase exciter is used, it is rotated by half the step per unit pulse, that is,

The bipolar drive of the stepper motor has two polarities to alternately change the polarity of the current to be passed through the winding. It has the merit of precisely controlling the angle of the stepper motor as compared with the unipolar drive. Torque is good even in the inside. On the other hand, the bipolar driving has a disadvantage that the torque is lowered at a high speed, and therefore, the demolding is apt to occur.

As shown in Fig. 1, L297 and L298 are commonly used as a dedicated driver IC for an apparatus for driving a stepping motor. At this time, L297 contains all circuits for driving the stepper motor with constant current, and L298 includes two H bridge drive circuits for bipolar drive. Therefore, the conventional stepping motor driving apparatus is implemented using two IC elements, resulting in a complex circuit configuration, a large volume, and a large cost.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a drive device for a stepping motor capable of driving a stepping motor by constituting a drive circuit of a stepping motor with simple elements.

According to an aspect of the present invention, there is provided a step motor driving apparatus including a plurality of switching units for receiving a pulse input signal and switching the pulse input signal to a motor control signal, The plurality of switching units including: a transistor that is operated by the pulse input signal to generate the motor control signal; and a control unit that is connected in parallel to the transistor, And a free wheeling diode that forms a current path during driving to consume energy stored in the coil of the step motor.

In the driving apparatus for a step motor according to the present invention, the pulse input signal is composed of two normal signals a and b and two reverse-phase signals a 'and b' for each phase, A pair of said switching parts is connected for each of the input signals.

The drive apparatus drives the step motor in a bipolar two phase excitation manner so that a pair of the motor control signals are generated respectively in two coils of the step motor.

In the driving apparatus for a step motor according to the present invention, each of the transistors included in the plurality of switching units has the same delay time.

The present invention can drive a stepper motor by constituting a stepper motor drive circuit with simple elements without using an expensive drive IC.

The present invention reduces the size of the entire circuit configuration and reduces the cost by driving the step motor by bipolar driving and two-phase excitation using a plurality of transistors.

FIG. 1 is a circuit diagram showing a driving device of a step motor composed of two ICs of L297 and L298 according to the related art; FIG.
2 is a block diagram schematically showing a configuration of a drive apparatus for a stepping motor according to the present invention;
3 is a circuit diagram showing an example of a drive apparatus for a step motor according to the present invention;
4 is a diagram for explaining a signal input / output relationship in a driving apparatus for a step motor according to the present invention;
5 is a view for explaining the operation of a driving apparatus for a step motor according to the present invention;
6 is a diagram for explaining an example of driving for three consecutive pulses in a two-phase excitation operation of a three-phase stepping motor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a driving apparatus for a step motor according to the present invention will be described in detail with reference to the accompanying drawings.

2, the driving apparatus 100 for a step motor according to the present invention includes a plurality of switching units 110 to 180 that receive a pulse input signal and convert the pulse input signal into a motor control signal, The stepping motor 200 is driven by supplying a motor control signal to the stepping motor.

3 and 5, the plurality of switching units 110 to 180 may include transistors U110 to U180 that are operated by the pulse input signal to generate the motor control signal, And a free wheeling diode (D180) that forms a current path during driving of the step motor to consume energy stored in the coil of the step motor.

Referring to FIG. 3, the pulse input signal is composed of two normal signals a and b and two inverted phase signals a 'and b' for each phase. The switching unit of the pair is connected. That is, a pair of switching units 110 and 120 are connected to the pulse input signal a, and the pair of switching units are composed of transistors U110 and U120 and freewheeling diodes D110 and D120, respectively. Also, the pulse input signal a '(

A pair of

switching units

130 and 140 are connected, and the pair of switching units are composed of transistors U130 and U140 and freewheeling diodes D130 and D140, respectively. The pulse input signals b and b 'are similarly configured. Therefore, the driving apparatus of the present invention is composed of eight transistors and eight freewheeling diodes connected in parallel. Of course, the number of transistors and diodes can be determined differently depending on the driving method and the like. The free wheeling diodes D110 to D180 are flyback diodes that maintain the flow of the induction current when the transistor is turned off, that is, when the power applied to the step motor is turned off, And is slowly reduced through the self-resistance component of the motor, thereby preventing the transistor, the driving device, and the step motor from being damaged.

Here, the driving apparatus 100 drives the step motor 200 in a bipolar two-phase excitation mode so that a pair of the motor control signals are generated in two coils of the step motor 200. The bipolar drive of the step motor 200 has two polarities to alternately change the polarities of the currents to be passed through the windings. It is possible to precisely control the angle of the step motor in comparison with the unipolar drive And the torque is good even in low speed. Referring to FIG. 6, a two-phase excitation is most widely used in a manner that current is always passed over two phases. The current consumption needs to be doubled for one-phase excitation, but the maximum holding torque increases by only √2, resulting in poor efficiency. However, since the damping characteristics are good, overshoot and undershoot that occur during rotation are reduced. Figure 6 shows the motion of the rotor during two-phase excitation for the same case. As shown in the first figure, when the phase 1 and phase 2 are excited at the same time, the rotor is in the middle position unlike the phase 1 excitation, and when the excitation winding is switched as shown in the second figure, Can be seen.

Referring to FIG. 4A, when the pulse input signal a becomes a high signal (Vcc signal), a signal on a 'must be applied to the motor. Also, when the b-phase is a high signal, the signal b 'must be a signal. Each of the transistors U110 to U180 included in the plurality of switching units has the same delay time. In the case of a general motor driving apparatus, a dead time is set between the switching elements to prevent arm short. Here, the short circuit occurs when Vcc and GND are short-circuited for a short period of time and the circuit is broken, for example, when two transistors U110 and U120 corresponding to each other of the switching part are turned on at the same time. Such a short circuit phenomenon can be easily solved by using a transistor having the same specifications, that is, a transistor having the same delay time and taking a pulse input signal as shown in FIG. 4A. Referring to FIG. 4B, the motor control signals generated by the pulse input signals a, a ', b, b' are A, A '(

), B, B '(

).

Referring to FIG. 5A, when the pulse input signal a is high and a 'is low, the transistors U120 and U130 in the switching units 120 and 130 connected to a' I never do that. In this case, the transistor U110 is operated by the pulse input signal a, the state of the motor control signal A becomes high, the transistor U140 operates, and the state of the motor control signal A 'is low, So that a path from A to A 'is formed. The same operation is performed when the pulse input signal b is high and b 'is low. That is, when b 'is low, the transistors U160 and U170 in the switching units 160 and 170 connected to b' do nothing. In this case, the transistor U150 in the switching unit 150 operates by the pulse input signal b, the state of the motor control signal B becomes high, and the transistor U180 in the switching unit 180 operates The state of the motor control signal B 'becomes low so that a path from B to B' is formed.

FIG. 5B shows a path opposite to FIG. 5A. Referring to FIG. 5B, when the pulse input signal a is low and a 'is high, the transistors U110 and U140 in the switching units 110 and 140 connected to a do nothing. In this case, the transistor U120 operates by the pulse input signal a ', and the state of the motor control signal A' becomes high, the transistor U180 operates, and the state of the motor control signal A becomes low, A is formed. When b is low, the transistors U150 and U180 in the switching units 150 and 180 connected to b do not operate. In this case, the transistor U160 in the switching unit 160 operates by the pulse input signal b ', and the state of the motor control signal B' becomes high, and the transistor U170 in the switching unit 170 operates, The state of the control signal B becomes low so that a path from B 'to B is formed.

INDUSTRIAL APPLICABILITY As described above, the stepping motor driving apparatus according to the present invention can drive the stepping motor by constructing the stepping motor drive circuit with simple elements without using an expensive driving IC. The present invention reduces the size of the entire circuit configuration and reduces the cost by driving the step motor by bipolar driving and two-phase excitation using a plurality of transistors. The stepping motor and stepping motor driving apparatus according to the present invention can be used in various application fields. In particular, the present invention can be used for household appliances such as a refrigerator control of a Kimchi refrigerator, a refrigerator damper control, and the like.

100: Driving device 200: Step motor
110 to 180:

Claims

And a plurality of switching units for receiving a pulse input signal and for switching the pulse input signal to a motor control signal,
And a step motor drive circuit for supplying the motor control signal to the step motor to drive the step motor by a bipolar drive method,
Wherein the plurality of switching units comprises:
A bipolar transistor operating by the pulse input signal to generate the motor control signal; And
And a free wheeling diode connected in parallel to the transistor and consuming energy stored in a coil of the step motor by forming a current path during driving of the step motor,
And the step motor is driven by the bipolar drive method.

The method according to claim 1,
The pulse input signal is composed of two normal signals a and b and two opposite phase signals a 'and b' for each phase,
And a pair of the switching units is connected to each of the four pulse input signals.

3. The method of claim 2,
Wherein the drive unit drives the stepper motor in a bipolar two phase excitation manner so that a pair of the motor control signals are generated respectively in two coils of the stepper motor.

4. The method according to any one of claims 1 to 3,
Wherein each of the transistors included in the plurality of switching units has the same delay time.