JP2002186272A - Motor controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To assure high quality control of motor by preventing generation of noise and vibration from the motor. SOLUTION: This motor controller is provided with a motor 21, an inverter circuit 27, a first calculation means 32 for outputting a threshold signal in the DC level based on a feedback velocity signal S12 from the motor 21 and a velocity command signal S11 corresponding to the reference rotating velocity, voltage limiting circuits R4, R5 which are provided in the first calculation means 32 to limit the saturation voltage of the first calculation means 32 to the level under the predetermined voltage which can be determined as desired, and a second calculation means 35 for outputting a switching control signal of an inverter circuit 27 under the pulse width modulation by the threshold signal and a triangular signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor control device for controlling the rotation state of a motor such as a DC motor that performs forward rotation or reverse rotation.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram showing the electrical configuration of a typical prior art control device 1 for a motor 2. As shown in FIG. Less than,
The control device 1 will be described with reference to FIG.

The control device 1 controls the rotational state of a three-phase motor 2 as an example. The motor 2 is provided with a magnetic pole detecting element 3 such as a hall element for each phase. The change in the magnetic flux density of the rotating magnetic field for each phase of the motor 2 is detected. Thus, the magnetic pole detection element 3 detects the rotation speed and the rotation direction of the motor 2 and the position in the rotation direction.

The control device 1 includes, for example, an input / output command signal control unit (hereinafter referred to as a control unit) 4 composed of a microcomputer or the like, and further has a rotation speed at which a position signal P from the magnetic pole detection element 3 is input. The measurement unit 5 is provided. The rotation speed signal from the rotation speed measurement unit 5 is input to the control unit 4.

[0005] A speed command signal corresponding to the reference rotation speed is separately input to the control unit 4. Based on the rotation speed signal and the speed command signal, a control having a characteristic of eliminating a deviation between these signals is performed. The signal is input to the logic circuit 6,
In the logic circuit 6, a control signal for turning on / off each transistor of the inverter circuit 7 is created and output to the inverter circuit 7. A DC power supply is connected to the inverter circuit 7, and a voltage / current from the DC power supply is modulated by the inverter circuit 7 and supplied to the motor 2. Thus, the motor 2 is controlled to rotate at the reference speed based on the speed command signal.

A drive signal line 8 for supplying a drive signal from the inverter circuit 7 to the motor 2 is provided with a current detecting means such as a current transformer 9 as an example. It is discriminated whether the current is an overcurrent due to an overload of the motor 2 or the like. If the current is an overcurrent, a control signal is output to the logic circuit 6 to generate logic for stopping the motor 2.

[0007]

In the above prior art,
In order to detect an overcurrent, the current transformer 9 and the overcurrent detection unit 1 are used.
It is necessary to provide 0 and the like separately from the control unit 4, which causes a problem that the number of parts and the manufacturing cost increase.

Further, since the speed control circuit is built in the control unit 4, when the current limit is activated, the overcurrent detection unit 1
There is a problem in that the operation of the current limiting circuit of 0 and the switching frequency of the speed control are not synchronized, and operate at an irregular switching frequency.

For this reason, there occurs a problem that sound in the audible range is generated or vibration is generated from the motor 2, resulting in a quality problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a motor control device capable of preventing noise and vibration from the motor and improving quality. It is.

[0011]

According to a first aspect of the present invention, there is provided a motor control device for switching an on / off state of a driving AC current supplied to a motor via a driving signal line, and a driving circuit. First calculating means for outputting a DC level threshold signal based on an input signal having a level corresponding to the current level of the driving AC current in the signal line and a reference rotation speed command signal corresponding to the reference rotation speed of the motor; A voltage limiting circuit provided in the first calculating means for limiting the saturation voltage of the first calculating means to a level lower than a predetermined voltage; and a pulse width modulation circuit based on the threshold signal and the triangular wave signal, Second operation means for outputting a switching control signal for controlling a switching operation in the circuit.

[0012]

In the motor control device according to the first aspect of the present invention, the inverter circuit controls an on / off switching operation of a driving alternating current supplied to the motor via a driving signal line. The first calculating means generates a DC level threshold signal based on an input signal of a level corresponding to the current level of the drive AC current in the drive signal line and a reference rotation speed command signal corresponding to the reference rotation speed of the motor. Output. The voltage limiting circuit provided in the first calculating means limits the saturation voltage of the first calculating means to a level lower than a predetermined arbitrary voltage.

[0013] The threshold signal output from the first calculating means whose saturation voltage is limited to a level lower than a predetermined arbitrary voltage is input to the second calculating means. A triangular wave signal is also input to the second calculating means. The second arithmetic means outputs a switching control signal pulse-width modulated based on the threshold signal and the triangular wave signal to the inverter circuit,
The on / off switching operation of the driving AC current is controlled.

At this time, the saturation voltage of the first calculating means is limited to less than an arbitrary voltage determined by the voltage limiting circuit, and the degree of saturation voltage limitation by the voltage limiting circuit is appropriately selected. The current limiting operation can be performed at a timing synchronized with the switching frequency of the inverter circuit. As a result, it is possible to prevent a situation where sound or vibration in the audible range from the motor is generated when the switching frequency of the inverter circuit and the switching frequency in the current limiting operation are not synchronized. Can be achieved.

[0015]

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

FIG. 1 is a circuit diagram showing an electric configuration of a speed control circuit 29 of a control device 12 of a motor 21 according to one embodiment of the present invention. FIG. 2 is a block diagram showing an example of an electric configuration of the control device 12. FIG. 3 is a waveform chart showing the operation of the present embodiment.

Hereinafter, the electrical configuration of the control device 12 will be schematically described with reference to FIG.

The control device 12 has a three-phase motor 2 as an example.
1 to control the rotation state of the motor 21.
For example, a magnetic pole detection element 23 such as a Hall element is provided for each phase, and a change in the magnetic flux density of the rotating magnetic field for each phase of the motor 21 is detected. Thus, the magnetic pole detection element 23 detects the rotation speed and the rotation direction of the motor 21 and the position in the rotation direction.

The control device 12 includes, for example, an input / output command signal control unit (hereinafter, a control unit) 24 composed of a microcomputer or the like, and further includes a rotation to which a speed feedback signal S12 from the magnetic pole detection element 23 is input. A speed measuring unit 25 is provided. The speed feedback signal S12 from the rotation speed measuring unit 25 is input to the control unit 24.

A speed command signal S11, which is a reference rotation speed command signal corresponding to the reference rotation speed of the motor 21, is separately input to the control unit 24, and based on the speed feedback signal S12 and the speed command signal S11. A control signal having a characteristic of eliminating the deviation of these signals is input to a logic circuit 26, and a control signal for turning on / off a plurality of switching transistors (not shown) provided in an inverter circuit 27 in the logic circuit 26. Is generated and output to the inverter circuit 27. Inverter circuit 2
7, a DC power supply is connected, and a voltage / current from the DC power supply is modulated by an inverter circuit 27 to generate a drive signal. The drive signal is supplied to the motor 21 via a drive signal line 28. Thus, the motor 21 is controlled to rotate at the reference speed based on the speed command signal S11.

Hereinafter, referring to FIG. An electrical configuration of the speed control circuit 29, which is a main part of the present embodiment, will be described.

The speed control circuit 29 is provided as an example in the logic circuit 26, but the present invention is not limited to such a configuration example.

The speed control circuit 29 connects the non-inverting input terminal of the amplifier 32, which is the first calculating means, to the ground potential as a reference potential, and has the inverting input terminal connected to a reference speed signal corresponding to the reference rotation speed of the motor 21. S11 and a speed feedback signal S12 from the magnetic pole detection element 23 are input via resistors R1 and R2 connected in parallel with each other. The inverting input terminal of the amplifier 32 is connected to the amplifier 32.
Is connected in a negative feedback manner to the output terminal via a resistor R3.

The output S13 of the amplifier 32 is input to a non-inverting input terminal of a comparator 35, which is a second calculating means, via a resistor R4 connected in series to the output terminal of the amplifier 32. Here, the non-inverting input terminal of the comparator 35 is connected to the ground potential via the resistor R5. The triangular wave signal Str is input to the inverting input terminal of the comparator 35. The output S14 of the comparator 35 is output to the inverter circuit 27 as a control signal for controlling the switching mode of each switching transistor (not shown) of the inverter circuit 27. The resistors R1 to R5 form a voltage limiting circuit 31.

Hereinafter, the operation of this embodiment will be described with reference to FIG.

As an example, when the motor 21 is overloaded and a current limit is applied, the output S1 of the amplifier 32 is
3 is reduced to half of the saturation voltage as shown in FIG. Therefore, the comparator 35 outputs the output S14 shown in FIG. 3B based on the triangular wave signal Str shown in FIG. The conduction width L at this output S4
2 is about half of the conventional conduction width. Therefore, the current flowing through the motor 21 is limited to a predetermined current value corresponding to the current width L2.

The speed control circuit 29 including such a voltage limiting circuit 31 is constituted by using the logic circuit 27 for generating a drive current for the motor 21 as described above. The necessity of separately providing a current limiting circuit is eliminated, so that the number of parts and the cost can be reduced.

The comparator 3 in the speed control circuit 29
5 is synchronized with the switching frequency of the switching transistor of the inverter circuit 28, and the frequency of the output S14 is also constant. This prevents a situation in which audible noise or vibration occurs. When the frequency of the output S14 is outside the audible range, no noise is generated. Therefore, the motor 21
Quality can be improved in the rotation operation.

[0029]

As described above, in the motor control device according to the first aspect of the present invention, the voltage limiting circuit provided in the first calculating means is adapted to set the saturation voltage of the first calculating means to be lower than an arbitrary voltage which is less than a predetermined voltage. It was made to limit to the level of. Also,
The threshold signal output from the first calculating means whose saturation voltage is limited to a level lower than a predetermined arbitrary voltage is input to the second calculating means. A triangular wave signal is also input to the second calculating means. The second arithmetic unit outputs a switching control signal pulse-width-modulated based on the threshold signal and the triangular wave signal to the inverter circuit, and controls on / off switching operation of the driving AC current.

At this time, the saturation voltage of the first calculating means is limited to less than an arbitrary voltage determined by the voltage limiting circuit. The current limiting operation can be performed at a timing synchronized with the switching frequency of the inverter circuit. As a result, it is possible to prevent a situation where sound or vibration in the audible range from the motor is generated when the switching frequency of the inverter circuit and the switching frequency in the current limiting operation are not synchronized. Can be achieved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an electrical configuration of a speed control circuit 29 of a control device 12 according to one embodiment of the present invention.

FIG. 2 is a block diagram illustrating an example of an electrical configuration of a control device 12.

FIG. 3 is a waveform chart showing the operation of the present embodiment.

FIG. 4 is a block diagram showing an electrical configuration of a control device 1 for a motor 2 according to a conventional technique.

[Explanation of symbols]

 Reference Signs List 21 motor 22 control device 24 control unit 25 rotation speed measurement unit 26 logic circuit 27 inverter circuit 29 speed control circuit 31 voltage limiting circuit 32 amplifier 35 comparator S11 reference speed signal S12 speed feedback signal S14 pulse width modulation signal R1 to R5 resistance Str Triangle wave signal

Claims (1)

[Claims] An inverter circuit for switching on / off a driving AC current supplied to a motor via a driving signal line, and an input having a level corresponding to a current level of the driving AC current in the driving signal line. A first calculating means for outputting a DC level threshold signal based on the signal and a reference rotation speed command signal corresponding to the reference rotation speed of the motor; and a first calculation means provided in the first calculation means. A voltage limiting circuit for limiting the saturation voltage to a level less than a predetermined arbitrary voltage; a pulse width modulated based on the threshold signal and the triangular wave signal; and a switching control signal for controlling a switching operation in the inverter circuit. A motor control device, comprising: a second calculation unit.