JPH08251979A - Motor driver - Google Patents

Abstract

PURPOSE: To realize high speed rotary driving of a motor by additionally providing only a simple external circuit and utilizing a conventional motor drive circuit IC employing the motor drive system having no position detecting element as it is with no modification. CONSTITUTION: A counter electromotive force division circuit 18 is provided between stator windings 2a, 2b, 2c and driving transistors 7a, 7b, 7c. When a permanent magnet rotor 1 is rotary driven, counter electromotive forces induced in the stator winding 2a, 2b, 2c are divided by means of resistors 15a, 16a, 15b, 16b and 15c, 16c and fed to driving transistors 7a, 7b, 7c through transistors 17a, 17b, 17c. The transistors 17a, 17b, 17c have collector terminals connected with the stator winding 2a, 2b, 2c which are fed with currents from the driving transistors 7a, 7b, 7c through the transistors 17a, 17b, 17c.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor drive device, and more particularly, to omit a position detecting element adapted to detect an energization switching position by utilizing a counter electromotive voltage generated in a stator winding of a motor. Type motor drive device.

[0002]

2. Description of the Related Art In recent years, motors have been downsized along with the downsizing of assembled devices. From the viewpoint of saving the installation space of the position detecting element that detects the energized phase switching position when realizing the miniaturization of the motor, a motor drive device that drives the motor without the position detecting element has been proposed. Most of them are configured to detect the energization switching position by utilizing the counter electromotive voltage generated in the stator winding of the motor. For example, Japanese Patent Application Laid-Open No. 55-160980 discloses a motor drive device of this type.

A conventional motor drive device will be described below with reference to the drawings. FIG. 4 is a configuration diagram of a conventional motor drive device, and FIG. 5 is a waveform diagram of essential parts in the conventional motor drive device.

In FIG. 4, the position detection circuit 11 for detecting the energized phase switching position and the drive transistors 7a, 7b,
A motor drive circuit 10 composed of 7c rotationally drives a DC motor composed of a permanent magnet rotor 1 having four poles magnetized and stator windings 2a, 2b and 2c.

The stator windings 2a, 2b, 2c are Y-connected, and their common terminals are connected to a DC power source 8 having a voltage value Vm. The stator windings 2a, 2b and 2c are connected to the collector terminals of the drive transistors 7a, 7b and 7c, respectively. The respective emitter terminals of the drive transistors 7a, 7b, 7c are commonly connected and grounded via the current detection resistor 9. That is, the drive transistor 7a,
Of 7b and 7c, the drive transistor corresponding to the input signal having the largest base input signal input to each base terminal is selectively turned on.

When the permanent magnet rotor 1 rotates, the stator windings 2a, 2b, 2c have a sinusoidal back electromotive force around the voltage Vm of the DC power source 8 as shown in FIG. 5 (a). 12
a, 12b, and 12c occur. Note that (Fig. 5 (a))
The shaded area in indicates the voltage drop due to the current flowing through the stator winding 12a.

In FIG. 4, the position detection circuit 11 is
An energized phase switching position signal is created from these back electromotive voltages, and signals for selectively driving the drive transistors 7a, 7b, 7c are generated. That is, the rectifier circuits 3a, 3b, 3
In c, a non-conducting region (here, a portion above the voltage Vm) of the counter electromotive voltage generated in each of the stator windings 2a, 2b, 2c is taken out. Projection type voltage-current conversion circuits 4a, 4b,
4c converts the half-wave waveform of the back electromotive force obtained by the rectifier circuits 3a, 3b, 3c into a current for charging the time integration capacitors 6a, 6b, 6c, and the suction type voltage-current conversion circuits 5a, 5c.
b, 5c are time-integrated capacitors 6a, 6b, 6c which are half-wave waveforms of the back electromotive force obtained by the rectifier circuits 3a, 3b, 3c
Converts the electric charge stored in the discharge current. As a result, voltage signal waveforms as shown in (FIG. 5 (b)), (FIG. 5 (c)), and (FIG. 5 (d)) are obtained in the time integration capacitors 6a, 6b, and 6c, respectively. It is input to the base terminals of the drive transistors 7a, 7b, 7c. As a result, the stator windings 2a, 2b, 2c have
Current waveforms 13a, 13b, 13c are supplied as shown in (e)).

Although not shown, the voltage of the current detection resistor 9 is usually detected to drive the drive transistors 7a and 7a.
Each base current is controlled so that the current supplied to the stator windings 2a, 2b, 2c by b, 7c becomes a predetermined value.

Further, as described above, there is a tendency toward miniaturization of equipment in recent years, and the motor drive circuit 10 as described here is used.
Are integrated circuits (hereinafter referred to as ICs) and are commercially available.

[0010]

By the way, for example, a helical scanning type video tape recorder (hereinafter referred to as VTR).
With the recent digital recording, it is necessary to rotate the rotary head faster than before to increase the recording transmission rate and to drive the rotary motor of the rotary head at high speed. Is coming.

When the motor is driven to rotate at high speed, the counter electromotive voltage generated in the stator winding increases in proportion to the rotation speed.
This means that the voltage applied to the drive transistor in the motor drive circuit becomes large, and it is necessary to use a transistor having a higher withstand voltage characteristic. As described above, since it is necessary to satisfy the miniaturization of equipment at the same time, the motor drive circuit needs to be integrated, and the conventional motor drive circuit IC must be changed. There is a problem that it takes time and development cost is required.

According to the present invention, by simply adding a simple external circuit, the conventional motor drive circuit IC adopting the motor drive system of the position detecting element omitted type can be used as it is without any change, and the motor can rotate at high speed. The first purpose is to realize driving.

A second object is to simultaneously realize a large motor drive current in order to shorten the starting time when the motor is driven at high speed.

[0014]

In order to achieve the first object, the motor drive device of the present invention is such that the common terminal of the Y-type connected motor stator winding group is connected to a DC power source.
The other terminal of the motor stator winding group is connected to the drive transistor group, and the energization phase switching position is detected by using the counter electromotive voltage generated in each of the motor stator winding group to detect the motor stator. In a motor drive device of a position detection element omitted type configured to sequentially selectively turn on / off the drive transistor group so as to sequentially selectively drive the winding group,
The connection between the other terminal of the stator winding group and the drive transistor group is cut, and each other terminal of the stator winding group is connected to a resistor in which first and second resistors are connected in series. The collector terminal is connected to each other terminal of the stator winding group, each emitter terminal is connected to each drive transistor group, and each base terminal is connected to each of the first and second terminals. It comprises a transistor group to which each of the series connection contacts of the second resistor is connected.

In order to achieve the second object,
In the motor drive device of the present invention, the common terminal of the Y-type connected motor stator winding group is connected to the DC power supply, the other terminal of the motor stator winding group is connected to the drive transistor group, and the motor fixing unit is connected. The energizing phase switching position is detected by using the counter electromotive voltage generated in each of the child winding groups, and the driving transistor groups are sequentially and selectively selected to sequentially and selectively drive the motor stator winding groups. In a motor drive device of a position detection element omitting type configured to be turned on / off, the connection between the other terminal of the stator winding group and the drive transistor group is cut, and the stator winding group is disconnected. Each other terminal is grounded through a resistor in which first and second resistors are connected in series, each of the drive transistor groups is connected to each emitter terminal, and each base terminal is connected to each of the first and second drive transistors. Second resistor in series Each of the continuous contacts is connected, and a current mirror circuit group for obtaining a current having a current ratio N (N is a positive real number) times the current supplied by each of the drive transistors is connected to each collector terminal. And a current output terminal of each of the current mirror circuit groups is connected to another terminal of each of the stator winding groups.

[0016]

According to the motor drive device of the present invention, for the first purpose, the counter electromotive voltage generated in the stator winding is divided by the first and second resistors and applied to the drive transistor group. Therefore, it is not necessary to change the drive transistor to one having a high breakdown voltage performance.

Further, for the second purpose, the current supplied from the drive transistor is amplified by the current mirror circuit and supplied to the stator winding, so that the motor current can be increased.

[0018]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram of a motor drive device according to an embodiment of the present invention for achieving the first object, and FIG. 2 is a waveform diagram of essential parts of the motor drive device. .

In FIG. 1, the same components as those of the conventional motor drive device shown in FIG. 4 are designated by the same reference numerals.

The motor drive device shown in FIG. 1 is different from the conventional motor drive device shown in FIG. 4 in that it has stator windings 2a, 2b and 2c and drive transistors 7a, 7b and 7c.
A counter electromotive voltage dividing circuit 18 is provided between c. Further, in order to realize high-speed rotation driving of the motor, a DC power supply 14 having a voltage Vm ₂ (> Vm) is installed in place of the DC power supply 8 having a voltage Vm in the conventional motor drive device.

When the permanent magnet rotor 1 is rotationally driven, as described above, the counter electromotive voltages 19a and 19b are applied to the stator windings 2a, 2b and 2c as shown in FIG. 2 (a). , 19c
Occurs. With respect to the operation waveform of the conventional motor drive device shown in (FIG. 5A), the counter electromotive voltage increases as the rotation speed increases. Further, the center voltage of the counter electromotive voltage is changed to the voltage Vm ₂ by changing the DC power supply.

Now, as shown in FIG. 1, the counter electromotive force generated in the stator winding 2a is the resistance 15a, 16
It is grounded and divided by the serial connection of a. Resistor 15a,
At the contact of 16a, a voltage generated by dividing the counter electromotive voltage generated in the stator winding 2a by the resistors 15a and 16a is generated,
The emitters of the transistors 17a, whose contacts are connected to the bases of the resistors 15a and 16a, have resistors 15a and 16a at their emitter terminals.
A voltage dropped by the base-emitter voltage from the contact voltage of a can be obtained. That is, as shown in FIG. 2B, the collector terminal of the drive transistor 7a is almost
The counter electromotive voltage generated in the stator winding 2a is applied to the resistors 15a, 16
A voltage waveform 20a divided by a is applied. Voltage waveform 20a
Center voltage Vc ₂ of the resistance voltage Vm ₂ of the DC power supply 14 1
It is a voltage dropped by the base-emitter voltage from the voltage divided by 5a and 16a.

Similarly, resistors 15b and 16b and a transistor 17b are similarly provided between the stator winding 2b and the driving transistor 7b, and a resistor 15c and a resistor 15c are provided between the stator winding 2c and the driving transistor 7c. 16c and a transistor 17c are similarly provided, and resistors 15a and 15c are also provided.
b and 15c have the same resistance value, and resistors 16a, 16b,
16c has the same resistance value. Then, the same operation is performed respectively, and as shown in (FIG. 2b), the stator windings 2b and 2b are connected to the collector terminals of the drive transistors 2b and 2c, respectively.
The voltage waveforms 20b and 20c are generated by dividing the counter electromotive voltage generated in 2c and dropping by the base-emitter voltage.

By the way, in (FIG. 1), in order to compensate for the operation in the rectifier circuits 3a, 3b, 3c (not shown in (FIG. 1) and the same as that shown in (FIG. 4)) in the position detection circuit 11. The voltage Vm ₂ of the DC power supply 14 is divided by the resistors 15d and 16d and the transistor 17d and input. As a result, the position detection circuit 11 has a stator winding 2a as shown in (FIG. 2 (c)), (FIG. 2 (d)) and (FIG. 2 (e)), as in the conventional motor drive device. , 2b, 2c generate position signals for switching the energized phases.

The collector terminals of the transistors 17a, 17b, 17c are connected to the stator windings 2a, 2b, 2c, and the driving transistors 7a, 7b, 7c are supplied as shown in FIG. 2 (f). The current to be applied is the transistor 17
stator windings 2a, 2b, 2 via a, 17b, 17c
c (current waveforms 21a, 21b, 21c).

When the motor rotates at high speed, the counter electromotive voltage generated in the stator winding increases in proportion to the rotation speed.
By adding a counter electromotive voltage dividing circuit 18 as shown in FIG. 1 to the conventional motor drive device, the drive transistor 7
The voltage applied to a, 7b, 7c can be kept low,
It is not necessary to replace the drive transistors 7a, 7b, 7c with transistors having a high breakdown voltage performance. That is, even if the motor drive circuit 10 is not changed at all,
High speed rotation drive of the motor can be realized.

Next, regarding the motor drive device of the present invention,
Another configuration example will be described. In other words, if the motor drive current required to maintain rotation increases due to an increase in load such as windage loss due to high-speed rotation drive, or if the startup time for high-speed rotation drive is about the same as conventional ones. It is possible to increase the motor drive current.
In these cases, in the motor drive device shown in (FIG. 1),
The current supply capability of the drive transistors 7a, 7b, 7c will be restricted.

FIG. 3 is a block diagram of a motor drive device according to an embodiment of the present invention for solving these problems (that is, for achieving the above-mentioned second object).

The permanent magnet rotor 1 rotates to rotate the stator winding 2
The counter electromotive voltage generated at a is divided by the resistors 22a and 23a, input to the drive transistor 7a of the motor drive circuit 10 via the base-emitter of the transistor 24a, and at the same time input to the position detection circuit 11. Similarly, for the drive transistors 7b and 7c, the stator windings 2b and
The counter electromotive voltage generated in 2c is divided and input, and also input to the position detection circuit 11. The voltage Vm ₂ of the DC power supply 14 is also input to the motor drive circuit 10 via the resistors 22d and 23d and the transistor 24d, and is also supplied to the position signal detection circuit 11.

The position detection circuit 11 produces a position signal for sequentially driving the drive transistors 7a, 7b, 7c in the same manner as described above.

The current supplied by the drive transistor 7a is
The diode 27a and the resistor 2 are connected via the transistor 24a.
5a. The diode 27a and the resistor 25a and the transistor 28a and the resistor 26a constitute a current mirror circuit, and the current supplied by the drive transistor 7a is amplified by the ratio of the resistor 25a and the resistor 26a and is supplied to the diode 31a and the resistor 29a. Further, the diode 31a
The resistor 29a, the transistor 32a, and the resistor 30a form a current mirror circuit.
The current a is supplied to the stator winding 2a at a ratio of the resistance 29a and the resistance 30a. That is, the current supplied from the drive transistor 7a is amplified by the two current mirror circuits and supplied to the stator winding 2a. Stator winding 2b, 2
Similarly for c, the currents supplied from the drive transistors 7b and 7c are amplified and supplied.

With this configuration, even when the permanent magnet rotor 1 rotates at high speed, the stator windings 2a, 2b, 2
The counter electromotive voltage generated in c is divided and applied to the drive transistors 7a, 7b, and 7c.
It is not necessary to improve the withstand voltage performance of a, 7b and 7c. In addition, even when the load increases due to windage loss during high-speed rotation and the motor current required to maintain rotation increases, the current supplied by the drive transistors 7a, 7b, 7c is amplified, and the stator winding is amplified. Since it is supplied to the lines 2a, 2b, 2c, it is not necessary to improve the current supply capability of the drive transistors 7a, 7b, 7c.

[0034]

As is apparent from the above description, according to the motor drive device of the present invention, the motor drive adopting the conventional position detection element omitted type motor drive system can be achieved only by adding a simple external circuit. It is possible to realize high-speed rotation driving of the motor by using the circuit IC as it is without any change.

Further, it is possible to simultaneously increase the motor drive current to shorten the starting time when the motor is driven at high speed.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a motor drive device according to an embodiment of the present invention.

FIG. 2 is a waveform diagram of essential parts in the motor drive device of the embodiment shown in FIG.

FIG. 3 is a configuration diagram of a motor drive device according to an embodiment of the present invention.

FIG. 4 is a configuration diagram of a conventional motor drive device.

FIG. 5 is a waveform diagram of essential parts in the conventional motor drive device shown in FIG.

[Explanation of symbols]

 2a, 2b, 2c Stator winding 7a, 7b, 7c Drive transistor 10 Motor drive circuit 11 Position detection circuit 17a, 17b, 17c Transistor 15a, 15b, 15c Resistor 16a, 16b, 16c Resistor

Claims (2)

[Claims] 1. A motor stator winding, wherein a common terminal of the Y-connected motor stator winding group is connected to a DC power source, and the other terminal of the motor stator winding group is connected to a drive transistor group. Using the back electromotive force generated in each of the groups, the conduction phase switching position is detected, and the drive transistor groups are sequentially turned on / off so as to drive the motor stator winding groups selectively. In the motor drive device of the position detection element omitted type configured as described above, each connection of the other terminal of the stator winding group and the drive transistor group is cut, and each of the stator winding group is disconnected. The other terminal is grounded via a resistor in which first and second resistors are connected in series, each other terminal of the stator winding group is connected to each collector terminal, and each emitter terminal is connected to the drive terminal. Each transistor group is connected The motor driving device comprising comprising a transistor group each of said first and second series connection contacts of the resistors is connected to each of the base terminal. 2. A common terminal of a Y-type connected motor stator winding group is connected to a DC power source, and another terminal of the motor stator winding group is connected to a drive transistor group, the motor stator winding. Using the back electromotive force generated in each of the groups, the conduction phase switching position is detected, and the drive transistor groups are sequentially turned on / off so as to drive the motor stator winding groups selectively. In the motor drive device of the position detection element omitted type configured as described above, each connection of the other terminal of the stator winding group and the drive transistor group is cut, and each of the stator winding group is disconnected. The other terminal is grounded through a resistor in which first and second resistors are connected in series, each emitter terminal is connected to each of the drive transistor groups, and each base terminal is connected to each of the first and second resistors. Each of the series connection contacts of the resistor And a current mirror circuit group for obtaining a current having a current ratio of N (N is a positive real number) times the current supplied by each of the drive transistors to each collector terminal. A motor drive device, comprising: a current output terminal of each of the current mirror circuit groups connected to another terminal of each of the stator winding groups.