JPH099691A - Drive controller of stepping motor - Google Patents

Abstract

PURPOSE: To prevent any through current to be generated when switching the currents flowing through motor coils, by providing waiting terms when determining the terms wherein currents are made to flow in a motor and switching the directions of the currents flowing through the motor coils. CONSTITUTION: Respective phase signals (PHA, PHB, PHC, PHD, PHA2, PHB2, PHC2, PHD2) are so outputted from a motor controller 1 as for currents to flow through winding coils L1, L2 in a motor. A region (A) is the term wherein a current of 380-400mA is made to flow through the winding coil L1 or L2, and a region (B) is the term wherein the phase signal PHA, PHB, PHC, or POD is so made to be 'L' as to interrupt the current fed from a power supply and the current is made to flow in the motor only by the energy stored in the winding coil, and further, a region (C) is a waiting term for switching the phase currents of the motor. That is, after the phase signals PHA, PHA2 are made to be 'L' and transistors Q1, Q2, Q3 are brought into OFF, the waiting term is provided before the phase signals PHC, PHC2 are brought into ON. Thereby, any through current is eliminated when switching the phase signal from PHA2 to PHC2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stepping motor drive control device.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 7, a drive control device for a bipolar stepping motor which controls a constant current of a stepping motor has two circuits of an H bridge of a transistor or an FET (one for each winding coil). Circuit). In FIG. 7, L1 and L2 are 2
It is the winding coil of the phase stepping motor.
4, Q7, Q10 are current control switches, Q2, Q5,
Q8 and Q11 are phase power switching switches, IC1 to IC4
Is a comparator for detecting the current flowing in the winding coil, I
C5 to 8 are AND gates, R5 to R12 are resistors for giving a hysteresis to the output of the comparator, and D1 and D.
2, D5, D6 are flywheel diodes, D3, D
4, D7 and D8 are diodes for back electromotive force protection, C1 is a capacitor for counter current through absorption for back electromotive force absorption, 1 is a motor controller (CPU) that outputs a phase signal of the motor at the timing when the motor rotates, R1 to R4 Is a resistance for current detection.

Next, the operation will be described. When a current is applied to L1 in the right direction in FIG. 7, the motor controller 1 sets the signal line PHA to “H (high)”. No current is flowing through the current detecting resistor R1, so that no voltage is generated at R1. Therefore, the output of the comparator IC1 is "
H ”is output, the signal line and PHA1 output“ H ”, Q3 and Q1 are turned on, and a current flows in the right direction to L1 from the power line signal line VNI through Q1. The current flows to R1 via Q2, and a voltage is generated at R1.When the divided voltage value of R5 and R6 of the voltage is higher than the reference voltage VREF, IC1 becomes "L".
(Low) ”, and when low, outputs“ H ”, and Q1 and Q
Turn 3 OFF / ON.

When Q1 and Q3 are turned off in L1, a current flows as shown in FIG. With this, constant current control is performed. FIG. 9 shows the current waveform.

In this manner, the coils are excited and the rotor inside the motor is rotated by sequentially passing currents in the left and right directions of the winding coils L1 and L2. FIG.
The waveforms of currents flowing through the signal lines PHA, PHB, PHC, PHD (hereinafter referred to as phase signals) and L1, L2 are shown at 0.

[0006]

However, in the above-mentioned conventional example, the through current flows at the timing shown in FIG. 11 based on the switching timing of the phase signals (PHA, PHB, PHC, PHD). This through-current flows through the path shown by the dotted line in FIG. 12 when switching between PHA and PHC, for example, which causes a problem that the ripple of the power supply line VNI becomes large.
Was using. When the power supply to the stepping motor is cut off, each phase signal is set to "L", but the current flowing in the coil L1 (L2) tries to continue flowing due to the characteristics of the coil, and Q2, Q
A back electromotive force is generated at the drains of Q5, Q8, and Q11. The back electromotive force returns to C1 via D3, D4, D7, and D8, but depending on the capacity of C1, there is a problem that the power supply line VNI is raised and the withstand voltage of C1 is exceeded. Used a high capacitor.

For the above-mentioned reasons, C1 requires a capacitor having a very large external size. Especially when the motor is driven by a battery, power saving is indispensable, but in the conventional control, the phase signal is "H",
When 1, PHB1, PHC1, and PHD1 are "H", electric power is always supplied from the power source to the motor, so no power saving measures have been taken.

Therefore, an object of the present invention is, firstly, to eliminate the through current, and secondly, to reduce the back electromotive force and save power.

[0009]

In order to achieve the above object, the present invention is, firstly, in the case where each transistor or FET (hereinafter referred to as a switch) of a motor driving H bridge is turned on before switching a phase signal. It is characterized by taking a wait (waiting period) until the switch that has been turned off completely and then switching the phase signal to eliminate the through current.

Secondly, the present invention conserves power by controlling the switches of the motor drive H-bridge at independent timings and shortening the time when power is directly supplied from the power supply to the motor as much as possible. When switching between phases, the back electromotive force is reduced by consuming as much power as possible stored in the coil.

[0011]

Next, embodiments of the present invention will be described. FIG.
1 is a drawing which best represents the present invention, in which 1 is a motor controller for controlling rotation of a motor, PHA, PHB, PH
C, PHD, PHA2, PHB2, PHC2, PHD2
Is a signal line controlled by the controller 1, VNI is a power supply line, C1 is a ripple preventing capacitor, L1 and L
2 is a winding coil of a two-phase stepping motor, Q1, Q
4, Q7, Q10 are PNP type FETs, Q2, Q5, Q
8, Q11 is NPN type FET, IC1, IC2, IC
3, IC4 is a comparator for detecting the current flowing in the winding coil, and IC5, IC6, IC7, IC8 are AN.
D gates, R5 to R12 are resistors for giving a hysteresis to the output of the comparator, D1, D2, D5 and D6 are flywheel diodes, D3, D4, D7 and D8 are counter electromotive force protection diodes, and C1 is ripple prevention. Capacitors, R1 to R4 are current detection resistors, and R13 to R16 are pull-up resistors for turning off Q1, Q4, Q7, and Q10.

Next, in the above-mentioned configuration, the motor controller 1 uses the phase signals (PHA, PHB, PHC, PHD, PHD).
HA2, PHB2, PHC2, PHD2) and outputs a current to the in-motor winding coils L1, L2. The operation of the motor controller 1 will be described later.

For example, the phase signals PHA and PHA2 are "H".
Then, Q2 is turned on, but no current is flowing through the current detection resistor R1, so that no voltage is generated across R1. Therefore, since the voltage is lower than the reference voltage VREF, the output of the comparator IC1 outputs "H", and AN
Since both input terminals of the D gate IC5 are "H", the signal line PHA1 becomes "H". This turns on Q3
Then, Q1 turns on, and a current starts to flow in L1 as shown by the solid line in FIG.

In this embodiment, the current flowing through L1 is 400
When the output becomes mA, the output of IC1 becomes "L".
Current detection resistor R so that it becomes "H" at 80mA
1. Hysteresis creating resistors R5, R6, reference voltage VR
EF is set.

That is, the controller 1 is PHA, PHA
After setting 2 to "H", current starts to flow in L1.
PHA1 becomes "L" when it reaches 0mA, and Q3
Turns off and Q1 turns off. At this time, because of the characteristics of the coil, L1 tries to continue to flow the current that has been flowing so far, and therefore continues to flow the current through the path indicated by the dotted line in FIG. this is,
The energy stored in L1 is gradually consumed by the internal resistance of L1 and the like, and the current flowing through L1 decreases. Then, when it becomes 380 mA, the output of IC1 becomes "H" again, and flows as shown by the solid line in FIG. In this way, the current flowing in L1 is 400 mA to 400 mA.
Flow between mA. FIG. 3 shows the current waveform and the phase signal timing, but the above description corresponds to the area A.

Next, the controller 1 sets PHA2 to "H".
The case where PHA is set to "L" without changing the value will be described. When PHA becomes "L", the signal line PH1 is always "L"
Therefore, both Q1 and Q3 are turned off, and the current flows as shown by the dotted line in FIG. This corresponds to the area B in FIG.

The above-mentioned operation is carried out by each phase signal (PHA, PHB,
PHC and PHD) respectively, so that a current is passed through the motor internal coils L1 and L2 to rotate the motor. The timing chart is shown in FIG.

In FIG. 4, a region A is a period in which a current is flowing through the winding coil L1 or L2 from 380 mA to 400 mA, and a region B is PHA, PHB, PHC or PHD.
L ", the power supply is cut off, and a current is supplied only by the energy stored in the coil. Area C is a wait time for switching the phase current. Areas A and B are shown in FIGS. It is the same period.

Providing this region C is the first aspect of the present invention.
The purpose is to eliminate the through current. That is PH
Set A and PHA2 to "L" to turn off Q1, Q2 and Q3
By providing a period from when the PHC and PHC2 are turned on to when the PHC2 and PHC2 are turned on, it is possible to eliminate the through current when the PHA2 and the PHC2 are switched.

The time of this region C is set to 10 μs in order to make it longer than the switching time due to the characteristics of Q1 and Q3.

Next, in the region B, a current is passed only by the energy stored in the coil. Providing this region B is to save power, which is the second object of the present invention. That is, in the period of the region B, the current is supplied only by the energy stored in the coil, and therefore the energy of the power source is not used. Therefore, the longer the area B is, the more power is saved.

The shaded area in FIG. 5 is the electric power saved by the power saving. Further, the provision of the region B also realizes the reduction of the counter electromotive force. That is, the energy stored in the coil between the regions B is consumed to some extent by the internal resistance and the like, so that the counter electromotive force is reduced by the consumed energy.

For example, in this embodiment, the power supply (VNI) is 12V. Before the region B is provided, when PHA is set to “L”, the drain of Q2 rises to about 16V, whereas when the region B is provided, it rises to only about 13V. The time for the region B in this example was about 50 μs. This time is set to the longest time without affecting the torque because the torque of the motor may be affected if the current flowing through the coil is excessively reduced.

Next, the operation of the motor controller 1 will be described with reference to FIG.
It will be described according to the flowchart of FIG. FIG. 6 is a flowchart according to the timing of FIG.

First, PHA, PHA2, PHD, PHD
2 is set to "H" (step S1). This gives L
Current begins to flow in 1 and L2. After outputting the phase signal,
The internal timer 1 is activated (step S2) (here, the internal timer 1 is a timer that measures the period of the area A in FIG. 4 and is the internal timer of the controller 1), and after timeout (step S3), PHD is set to "L" (step S4). This corresponds to the region B in FIG. 4, and energy is not supplied to the L2 from the power supply. PH
After setting D to "L", the internal timer 2 is activated (step S5). The internal timer 2 is a timer for measuring the period of the area B in FIG. In this embodiment, it is set to 50 μs. When the internal timer 2 times out (step S6), PHD2 is set to "L" (step S6).
7). This corresponds to the area C, and Q10 and Q12 are completely turned off. After setting PHD2 to "L", the internal timer 3 is activated (step S8). The internal timer 3 is a timer for measuring the period of the area C, and in the present embodiment, it is 10 μm.
s. When the internal timer 3 times out (step S9), the next phase signal PHB, PHB2
To "H". The above is repeated to rotate the motor.

[0026]

As described above, according to the present invention,
First, it is possible to reduce the size of the power supply components (capacitor, etc.) by completely eliminating the through current that may flow when the motor is driven.

In addition, according to the present invention, secondly, since the withstand voltage of the used parts of the power source can be lowered, the used parts can be downsized and the energy use efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a current path.

FIG. 3 is an explanatory diagram of a current waveform.

FIG. 4 is a timing diagram.

FIG. 5 is a diagram for explaining a current amount that can be saved.

FIG. 6 is a control flow chart of the present invention.

FIG. 7 is a circuit diagram of a conventional example.

FIG. 8 is an explanatory diagram of a current path of a conventional example.

FIG. 9 is an explanatory diagram of current limitation in a conventional example.

FIG. 10 is a timing and phase current waveform of a conventional example.

FIG. 11 is a diagram for explaining a through current waveform of a conventional example.

FIG. 12 is an explanatory diagram of a through current path of a conventional example.

[Explanation of symbols]

1 Motor controller C1 Power supply ripple capacitor L1, L2 Motor winding coil Q1, Q4, Q7, Q10 PNP type FET Q2, Q5, Q8, Q11 NPN type FET IC1 to IC4 Comparator IC5 to IC8 AND gate R5 to R12 Hysteresis resistance D1, D2, D5, D6 Flywheel diode D3, D4, D7, D8 Counter-electromotive force protection diode R1-R4 Current detection resistor R13-R16 Pull-up resistor

Claims (2)

[Claims] 1. A stepping motor drive control device for controlling a constant current of a stepping motor to drive it in a bipolar manner, wherein an H-bridge circuit composed of four switches for each motor coil and a direction of current flowing through the motor coil are set. It has a control means for switching, a time measuring means for deciding a time for flowing a current through the motor, and a time measuring means for providing a wait period when changing the direction of the current flowing through the motor coil, and switches the direction of the current flowing through the motor coil. A stepping motor drive control device, which is characterized by preventing a through current that occurs at the time. 2. A stepping motor drive control device for controlling a constant current of a stepping motor to perform bipolar drive, wherein an H bridge circuit composed of four switches for each motor coil and the four switches are independently provided. It has a control means for controlling and a timing means for controlling the four switches with a time lag, and the switch connected to the power source side among the four switches is turned off first,
By turning off the switch on the ground side with a time difference by the time measuring means, the coil energy is effectively used,
A stepping motor drive control device characterized by saving power and reducing back electromotive force.