JPH0469087A - Direct-current brushless motor drive control circuit - Google Patents

Abstract

PURPOSE:To prevent faulty start by vibrating an output shaft in low-speed operation such as start of a motor and stopping rotating the motor when the rotation direction of a rotation direction indication signal does not agree with that of a Hall rotation direction discrimination signal detected by a element. CONSTITUTION:When a rotation direction discrimination signal and a rotation direction indication signal which are detected from a motor 12 agree, a signal is transmitted from a monostable multi-vibrator 24 to a speed amplifier 32 via an LPF 28 and the motor 12 continues to rotate. If the signals disagree, a speed signal is not entered to the speed amplifier 32 because a rotation continuation signal entered to the LPF 28 is at level L. Therefore, the motor 12 is stopped. When a load put on an output shaft in low-speed operation in starting the motor 12 vibrates the output shaft and rotates the motor in the reverse direction to the direction indicated by the rotation direction indication signal, the speed signal is not entered to the reverse rotation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a drive control circuit for a DC brushless motor.

[Prior Art] Conventionally, there is a drive control circuit for a DC brushless motor as shown in the block diagram of FIG.

Reference numeral 112 indicates a three-phase DC brushless motor.

Reference numeral 114 is an inverter circuit that supplies drive current to the motor 112.

Reference numeral 116 denotes a power supply means for supplying DC motor current to the inverter circuit 114, for example, the motor current is output from an AC power source to the inverter circuit 114 via a rectifying and smoothing circuit and a chopper circuit.

Reference numeral 118 denotes a Hall element that detects the rotational position of the rotor of the motor 112, and for example, three Hall elements are provided around the rotor every 120 degrees.

Reference numeral 120 is a driver circuit. This driver circuit 120 receives the Hall element signal, rotation direction instruction signal, and speed control signal from the Hall element 118, controls the inverter circuit 114 according to the input signals, and finally controls the rotation direction and rotation of the motor 112. It determines the speed. Further, this driver circuit 120 outputs rotation pulses in accordance with the rotation speed of the rotor detected by the Hall element 118.

The code 122 is a monostable multivibrator, and the code 12
4 is a low pass filter (hereinafter referred to as LPF).

This monostable multivibrator 122 and L P F 1
24 converts the rotation pulse output from the driver circuit 120 into a speed signal.

A speed command circuit 126 controls the speed of the motor 112 by controlling this circuit 12B from the outside.

Reference numeral 12g denotes a speed amplifier, into which the speed signal output from the LPF 124 and the speed command circuit 126 is input, and this speed signal is amplified and output.

Reference numeral 130 is a pulse width modulation circuit (hereinafter referred to as PWM)
According to the speed signal input from the speed amplifier 128, the pulse width is modulated and output as a speed control signal. This output speed control signal is transmitted to the driver circuit 120.
The driver circuit 120 controls the inverter circuit 114 and determines the speed of the motor 112 according to the input control pulse.

In the drive control circuit 112 configured as described above, a rotation direction instruction signal is input to the driver circuit 120 and the motor 11 is
Controls the rotation direction of 2. In addition, when controlling the rotational speed of the motor 112, the speed command circuit 1
By controlling 2B, the rotational speed of the motor 112 is changed. Further, the PWM 130 is also controlled according to the rotation pulse output from the driver circuit 120, and the rotation speed of the motor 112 is controlled. As a result, motor 1]
This prevents the rotation speed of No. 2 from increasing above the set value.

[Problems to be Solved by the Invention] In the drive control circuit 110 having the above configuration, a load is applied when the motor 112 is started, and the output shaft vibrates, causing the motor to rotate in the opposite direction to the rotation direction indicated by the rotation direction switching signal. 112
may rotate.

In this case as well, the driver circuit 120 outputs a rotation pulse according to the speed of the rotor rotating in the opposite direction, and this pulse is output to the monostable multivibrator 122.
, L P F 124 and speed amplifier 128 .
W M 130 resulting in a speed control signal being input to driver circuit 120 .

Therefore, there is a problem in that the motor 112 starts rotating even though it is rotating in the opposite direction to the instructed rotation direction.

[Object of the Invention] In view of the above problems, the drive control circuit for a DC brushless motor of the present invention provides a circuit that does not output a speed control signal to the driver circuit when the motor is not rotating in the designated rotation direction. It is something.

[Means for Solving the Problem] As shown in the block diagram of FIG.
), an inverter circuit (2) that supplies a drive current to the DC brushless motor (1) according to a drive control signal and a speed control signal, and a Hall element (3) that detects the position of the rotor of the DC brushless motor (1). ), a rotation direction detection circuit (4) that determines the rotation direction of the rotor from the position detection signal from the Hall element (3) and outputs it as a rotation direction determination signal, and a rotation direction detection circuit (4) that instructs the rotation direction of the rotor from the outside. A driver circuit (6) that outputs a drive control signal to the inverter circuit (2) according to the rotation direction instruction signal and a position detection signal from the Hall element (3) and also outputs rotation pulses, and a driver circuit (6) that outputs rotation pulses and converts the rotation pulses into speed determination signals. A conversion circuit (7) that performs the conversion, and a comparison circuit that compares the rotation direction indicated by the rotation direction instruction signal and the rotation direction determined by the rotation direction determination signal, and outputs a rotation continuation signal if the rotation direction is the same. (8), a rotation continuation circuit (9) that controls the conversion circuit (7) to output a speed determination signal when a rotation continuation signal is input, and a speed determination signal and an external speed instruction signal. The speed control circuit (5) outputs a speed control signal in accordance with the speed control signal.

[Operation] In the drive control circuit for the DC brushless motor having the above configuration, the case where the direction of rotation indicated by the instruction signal coincides with the direction of rotation of the motor 1 will first be described.

A rotational direction instruction signal and a rotational direction determination signal output from the rotational direction detection circuit 4 in response to the position detection signal of the Hall element 3 are input to the comparison circuit 8 . In this comparison circuit 8, since the rotation direction indicated by the rotation direction instruction signal and the rotation direction determined by the rotation direction discrimination signal are the same direction, the comparison circuit 8 outputs a rotation continuation signal to the rotation continuation circuit 9. do. Since the rotation continuation signal is input to the rotation continuation circuit 9, the rotation continuation circuit 9 is controlled to output a speed determination signal to the conversion circuit 7. The conversion circuit 7 converts the rotation pulse into a speed discrimination signal and outputs it to the speed control circuit 5. The speed control circuit 5 outputs a speed control signal to the inverter circuit 2 according to the speed discrimination signal. Then, the driver circuit 6 controls the inverter circuit 2 according to the rotation direction instruction signal to drive the motor 1.

Next, a case will be described in which the rotation direction indicated by the rotation direction instruction signal and the rotation direction of the motor 1 are opposite directions.

A rotation direction instruction signal and a rotation direction determination signal are input to the comparison circuit 8. Since the rotation direction indicated by this rotation direction instruction signal and the rotation direction determined by the rotation direction determination signal are opposite directions, a rotation continuation signal is not output to the rotation continuation circuit 9. Therefore, in the rotation continuation circuit 9, the conversion circuit 7
control so that the speed discrimination signal is not output.

Since the speed discrimination signal is not input to the speed control circuit 5, no speed control signal is output, and therefore the driver circuit 6 stops the rotation of the motor 1.

[Example] Hereinafter, one embodiment of the present invention will be described based on the drawings.

FIG. 2 shows a block diagram of the drive control circuit 10 of this embodiment, and FIG. 3 similarly shows a circuit diagram of the drive control circuit 100.

Reference numeral 12 indicates a three-phase DC brushless motor.

Reference numeral 14 is an inverter circuit that supplies drive current to the motor 12. This inverter circuit 14 is composed of six NPN transistors and a diode connected in parallel to the transistors.

Reference numeral 15 denotes power supply means, which is composed of an AC power source, a rectifying and smoothing circuit, and a switching regulator.

Reference numeral 16 denotes a Hall element that detects the position of the rotor of the motor 12, and three Hall elements 16a, 1fib, 1
6c and more.

Reference numeral 18 is a driver circuit. This driver circuit 18 controls the inverter circuit 14 in accordance with the position detection signal from the Hall element 16 and the rotation direction instruction signal from the outside. That is, this driver circuit 1
Reference numeral 8 constitutes a logic circuit, which controls the base current of the transistor of the inverter circuit 14 to 0N10FFL and the drive current supplied to the motor 12. Further, this driver circuit 18 outputs rotation pulses.

Reference numeral 20 denotes a rotation direction detection circuit, which includes a Hall element 16.
A position detection signal output from the motor 12 is inputted thereto, and a rotation direction determination signal corresponding to the rotation direction of the motor 12 is outputted in accordance with the input position detection signal.

Reference numeral 22 is a comparison circuit into which a rotation direction instruction signal and a rotation direction determination signal are input. If both signals match, the rotation direction I! Outputs a continuation signal.

Reference numeral 24 denotes a monostable multivibrator, which receives rotation pulses from the driver circuit 8 and converts the rotation pulses into voltage signals.

Reference numeral 26 is an AND circuit into which the voltage signal from the monostable multivibrator 24 and the rotation continuation signal from the comparator circuit 22 are input. Then, the output signal is output only when both signals are input at the same time.

Reference numeral 28 is an LPF to which the output signal from the AND circuit 26 is input.

In addition, monostable multivibrator 24, AND circuit 26
and L P F 2, a conversion circuit in the claims.

Reference numeral 30 denotes a speed command circuit, which is a circuit for commanding the rotational speed of the motor 12.

Reference numeral 32 is a speed amplifier for amplifying the speed discrimination signal from the LPFZB and the speed instruction signal from the speed command signal 30.

Reference numeral 33 is a PWM, which modulates the output pulse width according to the signal output from the speed amplifier 32 and outputs it to the inverter circuit 14 as a speed control signal. This speed control signal controls 0N10FF of the upper stage or lower stage transistor of the inverter circuit I4. This changes the rotational speed of the motor 12.

Next, a third example of the circuit configuration of the Hall element 16, the rotation direction detection circuit 20, the comparison circuit 22, and the AND circuit 26 will be described.
The explanation will be based on the circuit diagram shown in the figure.

The position detection signals output from the three Hall elements 16a, 16b, and lee are sent to delay circuits 34a and 34, respectively.
b.

34c, the signal is input to decoders 36 and 38, which are powered by three people and have eight outputs. The decoders 36 and 38 are of the same type, and their input/output relationships are as follows.

A binary value with input terminal A of the decoder as the lower digit, B as the middle digit, and C as the upper digit is converted into the position of the output terminal corresponding to the decimal value.

In other words, when no H-level signal is input to the three input terminals, an output signal is output from the output terminal zO, and when only an H-level signal is input to the input terminal, an output signal is output from zl. If an H-level signal is input only to input terminal B, an H-level signal is output from z2, and the signals are sequentially output accordingly to input terminals A, B, and C.
When an H level signal is input to each of them, the configuration is such that an H level signal is output from z7. In this circuit, the output terminal Zl-26 of the decoder 38.38 is used. This decoder 38.38
The output signal output from AN is shown in FIG.
The D circuit, NOR circuit, OR circuit, and NAND AND circuit output a rotation determination signal. That is, the rotational direction detection circuit 20 is the decoder 38.31! and an AND circuit. As a result, the Hall element IBa,1
The rotational direction of the motor 12 is determined according to the position detection signals input from 8b and 18c, and a rotational direction determination signal is output.

For example, when the motor 12 is rotating clockwise with respect to the output shaft, the H level is output, and when the motor 12 is rotating counterclockwise, the rotation direction determination signal is output as the L level.

Next, the comparison circuit 22 will be explained.

Reference numeral 40 represents a NOT circuit, and reference numeral 42 represents an EX and OR circuit. The rotation direction instruction signal passes through the NOT circuit 40 to EX, O.
It is input to the input terminal of the R circuit 42. Further, the rotation determination signal is also input to the input terminal of the EX, OR circuit 42. In this case, as the rotation direction instruction signal, an H level signal is input when the motor I2 is rotated clockwise, and an L level signal is input when the motor I2 is rotated counterclockwise. As described above, when the levels of the rotation discrimination signal and the rotation direction instruction signal match, the EX/OR circuit 42 outputs an H level signal as a rotation/rotation continuation signal, and when they do not match, Outputs an L level signal.

When this rotation continuation signal is at H level, A
When the ND circuit 26 outputs a signal at H level and the rotation continuation signal is at L level, the AND circuit 26 outputs a signal at L level.

With the drive control circuit IO having the above configuration, when the rotation direction determination signal detected from the motor 12 and the rotation direction instruction signal match, the signal output from the monostable multivibrator 24 passes through the LPF 2g. The signal is input to the speed amplifier 32, and the motor 12 continues to rotate. However, if the rotation direction instruction signal and the rotation direction determination signal do not match, the rotation continuation signal input to L P F 2g is at L level, so no speed signal is input to the speed amplifier 32.

Therefore, motor 12 stops rotating.

The role of this drive control circuit 10 is that when the motor 12 is started up and operated at low speed, the output shaft vibrates due to the load applied to the output shaft and rotates in the opposite direction to the direction indicated by the rotation direction instruction signal. Even if it rotates, no speed signal is output for rotation in the opposite direction. Therefore, it is possible to prevent startup failures from occurring due to the influence of cogging of the motor 12.

In this embodiment, the speed control signal of the PWM 33 is inputted to the transistor of the inverter circuit 18, but it may be inputted to the switching regulator or the like of the power supply means 15 instead.

[Effects of the Invention] With the drive control circuit for a DC brushless motor having the above configuration, the output shaft vibrates during low-speed operation such as when starting the motor, and the rotation direction indication signal and the rotation direction detected by the Hall element are detected by the output shaft. If the rotation direction does not match the signal, the rotation of the motor is stopped.

Thereby, it is possible to prevent starting failures from occurring due to the influence of cogging of the motor.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a drive control circuit for a DC brushless motor according to the present invention, FIG. 2 is a block diagram of a drive control circuit showing an embodiment of the present invention, and FIG. 4 is a circuit diagram of a control circuit. FIG. 4 is a block diagram of a conventional drive control circuit. 7...Conversion circuit 8...Comparison circuit 9...Rotation continuation circuit [Explanation of symbols...DC brushless motor 2...Inverter circuit 3...Hall element 4...Rotation direction detection circuit 5...Speed control circuit 6...Driver circuit

Claims (1)

[Claims] 1. A DC brushless motor (1) and an inverter circuit (
2), a Hall element (3) that detects the position of the rotor of the DC brushless motor (1), and a rotation direction of the rotor that is determined from the position detection signal from the Hall element (3) and used as a rotation direction determination signal. A rotation direction detection circuit (4) that outputs a rotation direction signal that instructs the rotation direction of the rotor from the outside, and a drive control signal to the inverter circuit (2) in response to a position detection signal from the Hall element (3). A driver circuit (6) that outputs rotation pulses, a conversion circuit (7) that converts the rotation pulses into a speed discrimination signal, and a conversion circuit (7) that discriminates between the rotation direction indicated by the rotation direction instruction signal and the rotation direction discrimination signal. A comparison circuit (8) outputs a rotation continuation signal when the rotation direction is the same as the rotation direction, and a conversion circuit (7) outputs a speed discrimination signal when a rotation continuation signal is input. Driving a DC brushless motor characterized by comprising: a rotation continuation circuit (9) for controlling the rotation speed, and a speed control circuit (5) for outputting a speed control signal according to a speed discrimination signal and an external speed instruction signal. control circuit.