JPS63124791A - Drive for brushless motor - Google Patents

Abstract

PURPOSE:To obtain a sufficient position sensing signal even at low supply voltage by mounting a level-shift circuit on the outside of a position transducer. CONSTITUTION:The position of 1 needle for a motor is detected by position transducers 21-23, and outputs from the position transducers are input to a positional signal processing circuit 50 through a level-shift circuit 30. The level- shift circuit 30 properly level-shifts position sensing signals from the position transducers 21-23. The positional signal processing circuit 50 outputs conduction command signals to drive transistors 151-156 in response to outputs from the position transducers 21-23, and controls conduction to motor driving coils 201-203.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a drive device for a brushless motor used in audiovisual equipment and the like.

Conventional technology In recent years, drive motors for audio and video equipment have become longer-lived, more reliable, and thinner.
Instead of conventional DC motors equipped with mechanical switching mechanisms such as brushes and commutators, so-called brushless motors equipped with electronic switches using transistors are increasingly being used. As a conventional technology of the drive device, for example, Japanese Patent Publication No. 59-2
There is one as shown in FIG. 18 of Publication No. 7197.

An example of the above-mentioned conventional brushless motor drive device will be described below with reference to the drawings.

FIG. 4 shows a circuit diagram of a conventional brushless motor drive device. In FIG. 4, reference numerals 1 to 3 indicate position detectors for the movable element, which are constituted by, for example, Hall elements. The transistors 7.8 constitute a pair of differential transistors, and the output of the position detector 2 is connected to the base input. Transistors 9 and 10 form a pair of differential transistors, and the output of the position detector 1 is connected to the base input. The transistors 5 and 6 form a pair of differential transistors, and the output of the position detector 3 is connected to the base input. The common emitters of the transistor pairs 5 and 6 are connected to the constant current source 4, and the common emitters of the transistor pairs 5 and 6 are connected to the constant current source 4.
, 8 are connected to the collector of said transistor 5, and the common emitters of said transistor pair 9.10 are connected to the collector of said transistor 6. The collectors of transistors 7 and 10 are both connected to the base of transistor 12, the collector of transistor 8 is connected to the base of transistor 11, and the collector of transistor 9 is connected to the base of transistor 13. The collectors of the transistors 11 to 13 are connected to drive coils 14 to 16 of a motor (not shown), respectively.
and each emitter is connected to the positive power supply line.

The operation of the conventional brushless motor drive device configured as described above will be described below.

FIG. 5 is an explanatory diagram of the operation in FIG. 4, and the position detector of the mover detects A - C+! As shown, a signal having a phase difference of 120° is output. First, at the base inputs of transistors 7.8 and 9, 10 and 5.6, the position detector output is A>A.

When B<IIIJ, C>C, the output current of the constant current source 4 is supplied to the base of the transistor 12 through the transistors 5 and 7, the transistor 12 is turned on, and the drive coil 15 is energized. A>A, B<IIJ.

At the time of CTC, the output current of constant current source 4 is
．． 10 to the base of transistor 12;
The transistor 12 continues to be in the ON state and the drive coil 1
5 is energized. A>A.

B>U, C<C and A<A, B>IIJ, C<'CI
), the output current of the constant current source 4 is supplied to the base of the transistor 13 through the transistor 6.9, and the transistor 13 energizes the ONL drive coil 16. A
When B>U, C>'C and A>B>LC>C, the output current of the constant current source 4 is supplied to the base of the transistor 11 through the transistors 5 and 8, and the transistor 11 is ONL. The drive coil 14 is energized. As described above, the drive coils 14 to 16 are sequentially energized to drive the motor.

Problems to be Solved by the Invention However, in the above configuration, the power supply voltage is low (,
For example, when the voltage is about 1V, the base-emitter voltage of each transistor is 0.7V, and the collector-emitter saturation voltage is 0.7V. IV, there is no margin for circuit operation.Also, even if there was margin for operation, the voltage applied to each base of the differential transistor pair 5.6 would be 0.
．． 8V or more is required, and similarly differential transistor pair 7,
The voltage applied to each base of 8, 9, and 1o is required to be 0.9V or more. Therefore, the driving power supply voltage V of the position detectors 1 to 3
W is required to be more than IV, and 1V single power supply operation becomes impossible. Therefore, each differential transistor pair in FIG.
A method of configuring with NPs is considered, but in this case, the voltage applied to the base of each differential transistor pair is the value obtained by subtracting 0.8V and 0.9V from the power supply voltage (IV), that is, 0.2V.
And it needs to be 0.1v or less. Therefore, the drive voltage v)l of the position detector is 1v or less, which is less than the power supply voltage, and operation with a 1v single power supply is seemingly possible. However, if the voltage applied to the base of the differential transistor pair is about 0.1V,
The driving voltage of the position detector becomes extremely small, making it impossible to obtain a sufficient output as a position detector.

As described above, the conventional brushless motor drive device is
In 1V single power supply operation, there is not only no margin for circuit operation (when connecting the input part of the position detection signal processing circuit composed of a differential transistor pair to the position detector output part,
Various problems were occurring.

In view of the above problems, the present invention provides a brushless motor drive device that can be operated with a single 1V power supply.

Means for Solving the Problems In order to solve the above-mentioned problems, a brushless motor drive device of the present invention includes a multi-phase motor drive coil, a plurality of drive transistors, a position detector for a movable element, and a brushless motor drive device according to the present invention. The device is composed of a position detection signal processing circuit that generates an energization command signal to the drive transistor in accordance with a detector output, and a level conversion circuit provided between the position detector and the position detection signal processing circuit. .

Effect The present invention provides a level conversion circuit between the position detector and the position detection signal processing circuit, so that when transmitting the position detector output to the position detection signal processing circuit input at low power supply voltage, the position detector Even if the maximum drive voltage within the power supply voltage is applied, the position detector output can be transmitted to the position detection signal processing circuit by appropriately converting the level. In other words, it is possible to transmit a detection signal sufficient as a position detector to the position detection signal processing circuit even at a low power supply voltage.

EXAMPLE Hereinafter, a brushless motor drive device according to an example of the present invention will be described with reference to the drawings.

FIG. 1 shows a circuit diagram of a brushless motor drive device according to an embodiment of the present invention.

In FIG. 1, reference numerals 21, 22, and 23 indicate position detectors for the movable element, which are constructed of, for example, Hall elements. The position detectors 21 to 23 are each connected in parallel to a position detector drive power source 24. Each output of the constant current source 31.37 is connected via a resistor 43, and the constant current source 32.3
Each output of 8 is connected via a resistor 44, and is connected to a constant current source 33.
．． 39 are connected via a resistor 45, each output of the constant current source 34.40 is connected via a resistor 46, each output of the constant current source 35.41 is connected via a resistor 47,
Each output of the constant current sources 36 and 42 is connected via a resistor 48. The constant current sources 31-42, the resistors 43-4
8 constitutes a level conversion circuit 30. One output of the position detector 21 is connected to the output of the constant current source 31, and the other output is connected to the output of the constant current source 32,
One output of the position detector 22 is connected to the constant current source 33.
The other output is connected to the output of the constant current source 34, one output of the position detector 23 is connected to the output of the constant current source 35, and the other output is connected to the output of the constant current source 35. 36 outputs. Each base input of the differential transistor pair 57, 58 is connected to each output of the constant current source 37, 38, and the common emitter is connected to the positive side feed line 20 via the constant current source 51. Each base input of the differential transistor pair 59.60 is connected to the constant current source 39.4.
0, and a common emitter is connected to the positive feed line 20 via a constant current source 52. Each base input of the differential transistor pair 61 , 62 is connected to each output of the constant current source 41 , 42 , and the common emitter is connected to the positive side feed line 20 via the constant current source 53 . The collectors of the transistors 57 and 62 are commonly grounded via a constant current source 54 and are connected to a transistor 63.
is connected to the emitter of The transistor 58.
59 are commonly grounded via a constant current source 55 and connected to the emitter of a transistor 64. The collectors of the transistors 60 and 61 are commonly grounded via a constant current source 56, and the collectors of the transistors 60 and 61
It is connected to the emitter of 5. The transistor 63
The collector of transistor 64 is connected to the base and collector of transistor 67 and the base of transistor 68, and the collector of transistor 64 is connected to the base and collector of transistor 67.
The collector of the transistor 65 is connected to the base and collector of the transistor 71 and to the base of the transistor 72. The bases of the transistors 63-65 are both connected to a bias power supply 66, and the bases of the transistors 67-65 are connected to a bias power supply 66.
Each emitter of 72 is connected to the positive feed line 20. The respective collectors of the transistors 68, 70, and 72 are connected to respective outputs of constant current sources 73, 74, and 75, and are input to a forward/reverse switching circuit 80. The outputs U, V, and W of the forward/reverse switching circuit 80 are provided by transistors 151 and 15 whose emitters are connected to the positive power supply line 20, respectively.
2.153, said transistor 1
The collectors of transistors 51 to 153 are connected to the bases of transistors 154 to 156 whose emitters are grounded, and are also grounded via resistors 157 to 159. The collectors of the transistors 154 to 156 are respectively connected to one end of the motor drive coils 201 to 203, and the other ends of the motor drive coils 201 to 203 are connected to the positive side feed line 2.
Connected to 0.

The operation of the brushless motor drive device configured as described above will be described below.

FIG. 2 is a specific circuit connection diagram of the level conversion circuit 30 and position detection signal processing circuit input section for the position detector 21 in FIG. 1, and in FIG. 2, parts having the same functions as in FIG. The explanation will be omitted. In FIG. 2, assuming that the output current of the constant current source 45 is Is, the transistors 31, 32, 37 .
Each of the 38 output currents will be approximately equal to Is. Therefore, the output current of the transistor 31 is absorbed by the transistor 37 through the resistor 43 in just the right amount.

That is, a voltage drop occurs at both ends of the resistor 43 due to Is, and by connecting one end of the position detector 21 to one end of the resistor 43, the other end of the resistor 43 is connected to one end of the position detector 21. DC level conversion output can be obtained. The same applies to the other end of the position detector 21. This situation is shown in FIG.

On the other hand, the base input voltage range of the differential transistor pair 57.58 that constitutes the input section of the position detection signal processing circuit is 0.7V for the voltage between the base and emitter of each transistor, and 0.1V for the saturation voltage between the collector and emitter. Then, OV~
The power supply voltage becomes -〇, SV, and the power supply voltage becomes 1. When it is OV, it becomes 0V-0.2V. Therefore, the DC bias voltage of ali*as is about 0.15V, but even if the applied voltage of the position detector drive power supply 24 is increased to obtain a sufficient position detector output, the voltage of Is and the resistor 43 By adding or subtracting the value and adjusting the amount of level conversion, the position detector output can be transmitted to the position detection signal processing circuit. Similarly, each output of the position detectors 22 and 23 can be transmitted to the position detection signal processing circuit. The position detection signal transmitted to the position detection signal processing circuit 50 as described above passes through the forward rotation/reverse rotation switching circuit 80, sequentially turns on the drive transistors 151 to 156, supplies power to the motor drive coils 201 to 203, and supplies power to the motor drive coils 201 to 203. This is what drives the. The situation is similar to the operation explanatory diagram of the conventional example shown in FIG.

As described above, according to this embodiment, by providing the level conversion circuit between the position detector and the position detection signal processing circuit, the position detector output can be effectively converted into the position detection signal even at a low power supply voltage of 1V. It can be transmitted to the processing circuit and exhibits extremely excellent performance as a drive device for ultra-low voltage brushless motors.

Effects of the Invention As described above, the present invention provides a level shift circuit for the position detector output, so that when the position detector output is coupled to the position detection signal processing circuit input, the DC bias voltage can be set and the required position can be controlled. Problems such as securing detector output can be eliminated, and particularly excellent effects can be obtained in ultra-low voltage operation.

[Brief explanation of the drawing]

FIG. 1 is a circuit wiring diagram of a brushless motor drive device according to an embodiment of the present invention, FIG. 2 is a specific circuit wiring diagram of a level conversion circuit and a position detection signal processing circuit input section, and FIG.
2 is an explanatory diagram of the operation in FIG. 2, FIG. 4 is a circuit connection diagram of a conventional brushless motor drive device, and FIG. 5 is an explanatory diagram of the operation of FIG. 4. 21-23...Position detector, 30...
Level conversion circuit, 31-36...Current supply means, 37-42...Current absorption means, 43-48.
... Resistor, 50 ... Position detection signal processing circuit, 151-156 ... Drive transistor, 2
01-203...Motor drive coil. Name of agent: Patent attorney Toshio Nakao and one other person Figure 2 Figure 3 ND ■ ■ Figure 5

Claims (2)

[Claims] (1) a plurality of phase motor drive coils, a plurality of drive transistors, a movable element position detector, and a position detection signal processing circuit that generates an energization command signal to the drive transistor according to the output of the position detector; A brushless motor drive device comprising a level conversion circuit provided between the position detector and the position detection signal processing circuit. (2) A level conversion circuit is constructed by connecting current supply means, current absorption means for absorbing all the output current of the current supply means, and connecting the current supply means and the current absorption means with a resistor. A drive device for a brushless motor according to scope 1.