JPH0426390A - Driving circuit for brushless dc motor - Google Patents

Abstract

PURPOSE:To control the number of revolutions of a motor by a method wherein a inverter circuit which supplies a field current to a stator winding, a pulse width modulation circuit which outputs a control pulse to the inverter circuit, etc. are provided and the pulse width of the control pulse is varied by the pulse width modulation circuit. CONSTITUTION:An inverter circuit 12 which supplies a field current to the stator winding of a brushless DC motor 10, a pulse width modulation circuit 18 which outputs a control pulse to the inverter circuit 12, etc. are provided. In order to control the movement status of the motor 10, the inverter circuit 12 is operated by a certain DC voltage inputted through a first input terminal 24 and supplies the field current to the motor 10. The timing of the supply of the field current is given by a control pulse which is inputted from a logic circuit 16 through the pulse width modulation circuit 18. With this constitution, to the inverter circuit 12 the DC voltage inputted to the inverter circuit 12 can be constant and, further, the number of revolutions of the motor 10 can be controlled.

Description

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

[Prior Art] Conventionally, there is a drive circuit for a brushless DC motor as shown in FIG. That is, an inverter circuit 112 that supplies field current to the stator winding of the brushless DC motor 110, a logic circuit 114 that controls this inverter circuit 112 with control pulses, and this logic circuit 1.
A drive circuit 1 includes a Hall IC 116 that is connected to 14 and detects the position and rotation speed of the rotor of the brushless DC motor 110, and a rotation pulse circuit 118 that outputs the rotation speed of the brushless DC motor 110 as a rotation pulse.
It is 20.

In order to easily incorporate this drive circuit 120 into the motor 110, the input circuit 112, the logic circuit 114, and the rotation pulse circuit 118 are integrated and formed on one substrate.

When operating the motor 110, a DC voltage of 5V to 50V is supplied to the inverter circuit 112 from the switch jig power supply 124. In addition, the rotation pulse circuit 118
A rotation pulse corresponding to the rotation of the motor 110 is inputted to the microcomputer 122 from the motor 110 .

In response to this input rotation pulse, the microcomputer 122
By controlling the switching power supply 124, the inverter circuit 1
The rotation speed of the motor 110 was changed by changing the DC voltage supplied to the motor 12.

Furthermore, 5V is applied to the integrated circuit from the auxiliary power supply 12B.
This integrated circuit was operated by applying a DC voltage of .

[Problems to be Solved by the Invention] In the drive circuit 120 configured as described above, in order to control the motor 1100 rotation speed, it is necessary to change the output voltage of the switching power supply 124 by the microcomputer 122 as described above. Therefore, it is difficult to control it, and the circuit configuration other than the drive circuit 120 becomes complicated, which increases the cost and there is little point in integrating the drive circuit 120.

[Object of the Invention] In view of the above-mentioned problems, the present invention provides an integrated brushless DC motor drive circuit that can maintain a constant DC voltage input to an inverter circuit and control the rotational speed of the motor. be.

[Means for Solving the Problems] A drive circuit for a branless DC motor according to claim 1 of the present invention supplies field current to the stator winding of a branless DC motor 10, as shown in the block diagram of FIG. an inverter circuit 12 that outputs control pulses to the inverter circuit 12, a pulse width modulation circuit 18 that outputs control pulses to the inverter circuit 12, and a brushless DC motor lO
, a Hall element 20 for detecting rotational position provided in , a logic circuit 16 which receives the detection signal from the Hall element 20 and outputs a control pulse to the pulse width modulation circuit 18 , and an output signal from the logic circuit 16 . It consists of a rotation pulse circuit 22 that outputs a rotation pulse indicating the rotation speed of the motor 10, the inverter circuit 12, and the pulse width modulation circuit 1.
8. The logic circuit 16 and the rotating pulse circuit 22 are integrated to form an integrated circuit 11, the integrated circuit 11 is provided with a first input terminal 24 for supplying a constant DC voltage to the inverter circuit 12, and the pulse width is A second input terminal 26 for inputting a rotation control signal for controlling the rotation speed to the modulation circuit 18 is provided in the integrated circuit 11, and the rotation pulse circuit 22
The integrated circuit 11 is provided with an output terminal 30 for outputting rotational pulses from the integrated circuit 11, and a third input terminal 28 for supplying an operating voltage for the integrated circuit 11.

A drive circuit for a brushless DC motor according to a second aspect of the present invention, as shown in the block diagram of FIG. A pulse width modulation circuit 18 that outputs control pulses to the sensorless circuit 21 that detects the rotation speed using the field current from the inverter circuit 12, and a detection signal from the sensorless circuit 2I that inputs the detection signal to the pulse width modulation circuit 18. A logic circuit 16 outputs a control pulse, and a motor 1 is controlled by an output signal from the logic circuit 16.
It consists of a rotation pulse circuit 22 that applies a rotation pulse that indicates a rotation speed of 0, and the in-speed circuit 12, the pulse width modulation circuit 18, the sensorless circuit 21, the logic circuit 16, and the rotation pulse circuit 22 are integrated. An integrated circuit 11 is formed, a first input terminal 24 for supplying a constant DC voltage to the inverter circuit 12 is provided on the integrated circuit 11, and a rotation control signal is provided to the pulse width modulation circuit 18 for controlling the rotation speed. The second input terminal 26 for inputting the integrated circuit 11
an output terminal 30 for outputting rotational pulses from the rotational pulse circuit 22 is provided on the integrated circuit 11, and a third input terminal 28 for supplying an operating voltage for the integrated circuit 11;
is provided in the integrated circuit 11.

[Function] In order to control the operating state of the motor 10 by the drive circuit for the branless DC motor configured as claimed in claim 1, the first
Due to the constant DC voltage input from the input terminal 24,
The inverter circuit 12 is activated to supply field current to the motor 1o. The timing for supplying this field current is determined by inputting a control pulse from the logic circuit 16 to the inverter circuit 12 via the pulse width modulation circuit 18.

The number of rotations of the motor 1o is detected by the Hall element 20, and this number of rotations is sent to the rotation pulse circuit 22 through the logic circuit 16.
The signal is then output from the output terminal 3o.

Further, a rotation control signal corresponding to the rotation pulse is input from the second input terminal 26 to the pulse width modulation circuit 18 . This rotation control signal changes the width of the control pulse, changes the ON/OFF timing of the transistor in the inverter circuit 12, and changes the rotation speed of the motor IO.

Further, the operating power source of the integrated circuit 11 is supplied to the third input terminal 28
It is done by the voltage from.

In order to control the operating state of the motor 10 by the drive circuit for a brushless DC motor having the structure of claim 2, the first
With a constant DC voltage manually applied from the input terminal 24,
The inverter circuit 12 is activated to supply field current to the motor 10. The timing for supplying this field current is determined by inputting the control pulse from the logic circuit 16 to the inverter circuit 12 via the pulse width modulation circuit 18.
((Dingtsu.

Sensorless circuit 21 from the field current of inverter circuit) 2
The rotation speed of the motor 10 is detected by the logic circuit 16.
The signal passes through the rotation pulse circuit 22 and is outputted from the output terminal 30. Further, a rotation control signal corresponding to the rotation pulse is output from the second input terminal 26 to the pulse width modulation circuit 1.
8 is input.

By changing the width of the control pulse using this rotation control signal,
The QN and OFF timings of the transistors in the inverter circuit 12 are changed to change the rotation speed of the motor 1o.

Further, the operating power source of the integrated circuit 11 is supplied to the third input terminal 28
It is done by the voltage from.

[Heavenly Example] Hereinafter, one embodiment of the present invention will be described based on FIG. 3.

Reference numeral 10 is a molded motor type three-phase brushless DC motor.

Reference numeral 12 denotes an inverter circuit connected to the stator windings of the brushless DC motor 10, and by supplying field current from the second inverter circuit 12 to the three-phase stator windings, the brushless DC motor 10 is Rotate.

Reference numeral 14 denotes a current limiting circuit connected between the inverter circuit 12 and the stator winding, which prevents an excessive field current from flowing into the stator winding during startup or in the event of an accident. This is a circuit for

A logic circuit 16 outputs a control pulse to the inverter circuit 12. The control pulses from the logic circuit 16 control the drive and rotation direction of the motor IO.

Reference numeral 18 is a pulse width modulation circuit provided between the inverter circuit 12 and the logic circuit 16. This pulse width modulation circuit 18 changes the pulse width of the control pulse output from the logic circuit 16, and by changing the pulse width of the control pulse, the inverter circuit 1
The rotational speed of the motor 10 is changed by changing the ON%OFF timing of 2.

Reference numeral 20 denotes Hall ICs provided in the motor IO, and three Hall ICs are provided at every 120° around the rotor.

The detection signal of this Hall IC 20 reaches the logic circuit 16.

Reference numeral 22 denotes a rotation pulse circuit, which is connected to the logic circuit 16 and outputs rotation pulses in response to the output signal from the Hall IC 20.

The inverter circuit 12, the current limit circuit 14, the pulse width modulation circuit 18, the logic circuit 16, and the rotation pulse circuit 2
2 is integrated on one substrate to form one drive circuit.

Reference numeral 24 is an input terminal for inputting a 140V DC voltage to the inverter circuit 12.

Reference numeral 26 is an input terminal for controlling the rotation speed (No. 3 manually) to the pulse width modulation circuit 18.

Reference numeral 28 is an input terminal for inputting a DC voltage for operating the integrated circuit 11.

Reference numeral 30 is an output terminal for outputting rotation pulses from the rotation pulse circuit 22.

The input terminals 24, 26, 28 and the output terminal 3o are provided in the integrated drive circuit 11.

Reference numeral 32 is a 100V AC power supply.

Reference numeral 34 denotes a rectifying and smoothing circuit connected to the AC power supply 32, and a DC voltage of 140V is outputted through this rectifying and smoothing circuit.

The output terminal of this rectifying and smoothing circuit 34 and the input terminal 24 of the drive circuit 11 are connected.

Reference numeral 36 denotes an auxiliary power supply that supplies a 12V DC voltage to the input terminal 28 of the drive circuit 11. The AC power supply 32 supplies power to the auxiliary power supply 36 .

Reference numeral 38 denotes a microcomputer (hereinafter referred to as microcomputer), which is connected to the input terminal 26 and output terminal 30 of the drive circuit 11.

Next, the operating state of the drive circuit 11 of the motor 10 configured as described above will be explained.

An input voltage of 140V is input to the input terminal 24, and a DC voltage of 12y is input manually to the input terminal 28. In this state, from the microcomputer 38 to the input terminal 26
When a rotation control signal for starting rotation of the motor 10 is input through the inverter circuit 12, the current limiting circuit 1
4, the field current is supplied to the stator windings. Motor 1
0 starts rotating, the Hall IC 20 detects its rotational position, outputs a detection signal to the logic circuit 16, and the rotation pulse circuit 22 manually inputs the rotation pulse to the microcomputer 38 via the output terminal 30. When changing the rotation speed of the motor 10, the pulse width of the control pulse generated from the pulse width modulation circuit 18 or the logic circuit 16 is changed according to the rotation control signal from the microcomputer 38, and the control pulses with different pulse widths are transferred to the inverter. input to circuit 12; by this,
The field current supplied to motor lO changes and motor 1
0 rotation speed changes.

Incidentally, since the drive circuit 11 is integrated on one substrate, when the brushless DC motor 10 is molded, the drive circuit 11 is molded inside the brushless DC motor 10 at the same time. And the input terminals 24, 26
．． 28 and the output terminal 30 are left exposed from this molding motor 10. As a result, the input terminal 24
It becomes possible to control the rotation speed of the motor 10 by simply inputting a constant DC voltage to the motor 10. Further, in this case, heat radiation from the drive circuit J1 is performed from the mold of the motor 10.

Further, as shown in the block diagram of FIG. 4, in place of the Hall IC 20 of the first embodiment, a sensorless circuit 21 that detects the rotation speed of the motor IO by the field current output from the inverter circuit 12 is installed in the drive circuit. 11 may be integrated.

[Effects of the Invention] As described above, in the brushless DC motor drive circuit of the present invention, when changing the rotation speed of the motor, the pulse width of the control pulse is changed by the pulse width modulation circuit, thereby changing the rotation speed. You can change the number. Therefore, it is not necessary to supply the inverter circuit with a variable voltage depending on the rotational speed as in the conventional case, and a drive circuit suitable for integration can be provided.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a drive circuit according to claim 1 of the present invention, FIG. 2 is a block diagram showing a drive circuit according to claim 2, and FIG. 3 is an embodiment of the present invention. FIG. 4 is a block diagram of the drive circuit of the second embodiment, and FIG. 5 is a block diagram of a conventional motor drive circuit. It is. [Explanation of symbols] 10... Brushless DC motor 12... Inverter circuit 14... Current limiting circuit 16... Logic circuit 18... Pulse width modulation circuit 20 ... Hall IC 22 ... Rotation pulse 24 ... Input terminal 26 ... Input terminal 28 ... Input terminal 30 ... Output terminal

Claims (2)

[Claims] 1. A drive circuit for a brushless DC motor such as a molded motor, which includes an inverter circuit that supplies field current to the stator winding of the brushless DC motor, a pulse width modulation circuit that outputs control pulses to the inverter circuit, and a brushless DC motor. A Hall element for detecting the rotational position provided in the circuit, a logic circuit that receives the detection signal from the Hall element and outputs a control pulse to the pulse width modulation circuit, and an output signal from the logic circuit that indicates the rotational speed of the motor. The inverter circuit, the pulse width modulation circuit, the logic circuit and the rotary pulse circuit are integrated to form an integrated circuit, and the inverter circuit is configured to provide a constant DC voltage to the inverter circuit. A first input terminal is provided on the integrated circuit, a second input terminal is provided on the integrated circuit for inputting a rotation control signal for controlling the rotation speed to the pulse width modulation circuit, and the rotation pulse from the rotation pulse circuit is provided. A drive circuit for a brushless DC motor, characterized in that the integrated circuit is provided with an output terminal for outputting the output, and a third input terminal for supplying an operating voltage for the integrated circuit is provided in the integrated circuit. 2. A drive circuit for a brushless DC motor such as a molded motor, which includes an inverter circuit that supplies field current to the stator winding of the brushless DC motor, a pulse width modulation circuit that outputs control pulses to the inverter circuit, and an inverter circuit. A sensorless circuit that detects the rotation speed using the field current of the motor, a logic circuit that receives a detection signal from the sensorless circuit and outputs a control pulse to the pulse width modulation circuit, and an output signal from the logic circuit that indicates the motor rotation speed. It consists of a rotation pulse circuit that outputs rotation pulses, the inverter circuit, pulse width modulation circuit, sensorless circuit, logic circuit, and rotation pulse circuit are integrated to form an integrated circuit, and a constant DC voltage is supplied to the inverter circuit. The integrated circuit is provided with a first input terminal for inputting a rotation control signal for controlling the rotation speed to the pulse width modulation circuit, and the integrated circuit is provided with a second input terminal for inputting a rotation control signal for controlling the rotation speed to the pulse width modulation circuit. A drive circuit for a brushless DC motor, characterized in that the integrated circuit is provided with an output terminal for outputting rotational pulses, and the integrated circuit is provided with a third input terminal for supplying an operating voltage for the integrated circuit.