JPS627399A - Motor driving device - Google Patents

Abstract

PURPOSE:To suppress a spike voltage generated by a stator winding by modulating a driving current by a triangular signal at a timing for turning ON or OFF a driving transistor. CONSTITUTION:The output of a triangular wave oscillator 1 is converted by a pulse signal generator 2 to a pulse signal, and input to a distributor 3. The distributor 3 outputs a signal which repeats in a ring shape. Driving transistors 4a, 4b, 4c are turned ON and OFF repeatedly in response to the signal which repeats in the ring shape to forcibly and sequentially drive stator windings 5a, 5b, 5c. The output of the oscillator 1 modulates a driving current command 6, and suppresses the driving current at the position where the current phase is switched.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a motor drive device that is driven by forcibly energizing stator windings in sequence.

2. Description of the Related Art Examples of devices to which the present invention relates include stepping motors. A stepping motor uses a signal that repeats in a ring pattern to turn on and off the drive transistor connected to the stator winding, sequentially energizing each stator winding and driving it. From the perspective of the drive transistor, the stator The winding is an inductive load, and when the drive transistor changes from an on state to an off state, a high voltage appears between the emitter and collector of the drive transistor due to a sudden change in current, which may damage the drive transistor. Conventionally, the following methods have been used to suppress this spike voltage.

FIG. 5 shows the prior art, particularly the stator windings and drive transistors per phase. In the figure, 9 is a stator winding, 10 is a drive transistor, and 11 is a diode. Now, when the drive transistor 10 turns from the on state to the off state, the current flowing through the stator winding 9 does not suddenly become zero, but a forward current flows through the diode 11 in the direction shown by the arrow in the figure, and the drive transistor 10 The high voltage no longer appears on the collector.

Furthermore, FIG. 6 shows another conventional technique.

This is also shown for each phase as in FIG. 5.

Reference numerals 9 and 10 in the figure are exactly the same as those in FIG. 5, and are a stator winding and a drive transistor, respectively. 12 is a resistor, 13
is a capacitor. In FIG. 6, when the drive transistor 10 is turned from the on state to the off state, the stator winding 9
The capacitor 13 absorbs the spike voltage generated by the voltage. Note that the resistor 12 is provided to prevent resonance caused by the inductance of the stator winding 9 and the capacitance of the capacitor 13.

(For example, “Basics and Applications of Stepping Motors” No. 5
Problems to be Solved by the Invention According to such conventional technology, diodes, resistors, and capacitors must be attached to each stator winding in order to satisfy the safe operating area of the drive transistor. However, it also has the disadvantage of increasing the number of external parts. Moreover, when using the configuration shown in Figure 6, it was often necessary to use a capacitor with an extremely large capacity.Also, because the phase switching of the stator winding was abrupt, the drive current suddenly increased. There was also the problem that the changes caused vibrations and electromagnetic noise.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention suppresses the drive current using the triangular wave oscillator output at the timing when the energized phase is switched.

According to the present invention, the drive current is modulated by a triangular wave signal at the timing when the drive transistor turns on or off,
Therefore, the change in the current flowing through the stator winding becomes smooth, and the spike voltage generated in the stator winding is suppressed.

As a result, the safe operating area of the drive transistor is satisfied, and vibration and electromagnetic noise are also reduced.

Example FIG. 1 is a block diagram showing one embodiment of the present invention.

1 is a triangular wave oscillator, 2 is a pulse signal generator, and 3 is a distributor. 5a, 5b, and 5c are stator windings, respectively. 4a, 4b, 4c are stator windings 5a, 5b, respectively
, 5c, and 6 is a drive current command.

That is, the output of the triangular wave oscillator 1 is transmitted to the pulse signal generator 1.
The signal is converted into a pulse signal and input to the distributor 3.

The distributor 3 is composed of, for example, a ring counter and outputs a signal that is repeated in a ring manner. Then, the drive transistors 4a, 4b, 4c are sequentially turned on and off (repeatedly, the stator windings 5a, 5b, 5
c is forced to drive sequentially. This causes the rotor of the brushless motor to start rotating. Further, the output of the triangular wave oscillator 1 modulates the drive current command 6, and the drive current is suppressed at the point where the phase to which current is applied changes.

FIG. 2 is a waveform diagram of essential parts of the embodiment shown in FIG. 1.

That is, FIG. 2(1) shows the output waveform of the triangular wave oscillator 1, and FIG. 2(b) shows the output waveform of the pulse signal generator 2. FIG. 2(C), +d), (f!l) are the results of distributing the output of the pulse signal generator 2 through the distributor 3, and are the base input waveforms of the drive transistors 4a, 4b, and 4C, respectively.Furthermore, The drive current command 6 is modulated by the triangular wave oscillator 1, and here, the drive current is suppressed especially when the triangular wave becomes a trough, so the stator windings 5a, 5b
, 5c respectively.

Figure 2ff) (g) (The current shown in hl flows. In other words, this suppresses the transient voltage change due to the inductance of the stator windings 5a, 5b, and 5c that occurs when switching the energized phase. Drive transistor 4a.

This suppresses the jump in the collector potential of 4b and 4c.

Yet another embodiment of the invention is shown in FIG. Third
In the figure, 1.2, 3.4a, 4b.

4C, 5a, 5b, and 50.6 are completely equivalent to those shown in FIG. 1, and their explanation will be omitted here. 7 is a frequency divider that divides the output of the pulse signal generator 2; 8 is a logic circuit which logically processes the output of the pulse signal generator 2 and the output of the frequency divider 7, detects the timing of switching the energized phase performed by the output of the distributor 3, and generates a triangular wave at this timing. Drive current command 6 using the output of oscillator 1
This modulates the drive current and suppresses the drive current. Figure 4 shows the third
The main part waveform diagram of the figure is shown. Figure 4 (al is triangular wave oscillator 1
This is the output waveform of FIG. 2B shows the output waveform of the pulse signal generator 2. (C) of the same figure shows the output waveform of the frequency divider 7, and here specifically shows the result of 1/2 frequency division.

In addition, (d), (e), and (f) in the same figure show the output waveforms of the distributor 3, and the driving transistors 4a + 4b, 4, respectively.
It is input to the base terminal of c. Furthermore, if C1 is passed through the EX-OR gate circuit in the logic circuit 8, the waveform shown in FIG. The phase matches the timing at which the energized phase switches.

At this timing, when the drive current command 6 is modulated and suppressed by the output of the triangular wave oscillator 1 (waveform shown in FIG. 4(a)), the current shown in FIG. 4 (hl) flows as the drive current.At this time, the fixed prewinding vA5a, 5b.

The current shown in FIG. 4(1)(j)(g)) flows through 5c. That is, as a result of this, the current flowing through each phase when switching the energized phase changes smoothly, thereby suppressing the generation of a transient spike voltage due to the inductance of the stator winding.

Effects of the Invention As described above, according to the present invention, it is possible to suppress the spike voltage caused by the inductance of the stator winding without adding a diode, capacitor, or resistor to the stator winding, and it is possible to suppress the spike voltage caused by the inductance of the stator winding. The safe operation area can be satisfied. Furthermore, since the drive current flowing through each phase changes smoothly, vibration and electromagnetic noise are also suppressed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention, FIG. 2 is a main waveform diagram for explaining FIG. 1, and FIG. 3 is a block diagram showing another embodiment of the present invention. FIG. 4 is a main part waveform diagram for explaining FIG. 3. FIGS. 5 and 6 are diagrams showing conventional examples. 1...Triangular wave oscillator, 2...Pulse signal generator, 3...Distributor. Name of agent Patent attorney Toshio Nakao (1 person) Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] A triangular wave oscillator that generates a triangular wave signal, a pulse signal generator that generates a pulse signal in synchronization with the output of the triangular wave oscillator, and the output of the pulse signal generator is inputted, thereby sequentially energizing the stator windings. a distributor for obtaining a command signal for the motor drive, and the output of the triangular wave oscillator is used to suppress a stator winding drive current at the time of energization phase switching.