JP3380538B2 - Operation control device for DC motor - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a DC motor operation control device for controlling the number of revolutions using PWM control of a DC motor.

[0002]

2. Description of the Related Art In recent years, DC motors are highly efficient and
The range of applications is expanding due to the ease of controlling the rotation speed.

A conventional operation control method for a DC motor will be described below. Generally, the control of the rotation speed of the DC motor is
This is done by controlling the voltage applied to the electric motor.
In recent years, PWM control has been widely used as a method of changing this voltage. For example, it is possible to control the rotation speed by turning on / off the semiconductor switch on one side of the inverter circuit at a chopping frequency higher than the driving frequency. At this time, the voltage is adjusted by the on-off ratio of the chopping duty.

As an example of this method, for example, JP-A-63 / 1988
There is a method disclosed in Japanese Patent No. 234893. Hereinafter, such a conventional DC motor operation control device will be described with reference to the drawings.

FIG. 6 is a block diagram of a conventional DC motor operation controller.

In FIG. 6, reference numeral 1 is an AC power source. Reference numeral 2 denotes a voltage doubler rectifier circuit that converts the AC voltage of the AC power supply 1 into a DC voltage, and includes diodes 2a to 2b and capacitors 2c to.
2d is connected.

Reference numeral 3 is an inverter circuit, in which semiconductor switches (transistors) 3a to 3f are connected in a three-phase bridge, and diodes 3g to 3l are connected to the respective transistors in parallel and in opposite directions.

A DC motor 4 is driven by the output of the inverter circuit 3. A position detection circuit 5 detects a rotational position of a rotor (not shown) of the DC motor 4 and generates a rotation pulse, and detects a position from a counter electromotive voltage of the DC motor 4.

Reference numeral 6 is a commutation circuit for producing a signal for commutating the semiconductor switches 3a to 3f of the inverter circuit 3 from the output of the position detection circuit 5. Reference numeral 7 denotes a rotation speed command circuit, which generates a rotation speed command signal for the DC motor 4. Reference numeral 8 denotes a rotation speed detection circuit, which counts rotation pulses of the position detection circuit 5 for a certain period (for example, 0.5 seconds).

Reference numeral 9 denotes a duty setting circuit, which determines the duty ratio of the two from the difference between the rotation speed command signal of the rotation speed command circuit 7 and the actual rotation speed detected by the rotation speed detection circuit 8. Output the value. Reference numeral 10 is a chopping signal generation circuit, which produces a waveform having a different on / off ratio at a constant frequency in accordance with the duty value in order to make the rotation speed of the DC motor 4 variable.

Reference numeral 11 is a combining circuit for combining the output of the commutation circuit 6 and the output of the chopping signal generating circuit 10, and chops only one side arm of the inverter circuit 3. 12 is according to the output of the synthesis circuit 11,
A drive circuit for operating the semiconductor switches 3a to 3f of the inverter circuit 3.

[0012]

However, in the conventional fairness as described above, the control of the rotation speed is performed only by changing the on-off ratio of the chopping duty, so that the chopping duty is turned on at a low rotation speed. There was a problem that the efficiency decreased due to the decrease of the ratio.

The present invention solves the above-mentioned conventional problems, and an object of the present invention is to provide an operation control device for a DC motor, which suppresses a decrease in efficiency at low rotation speeds.

[0014]

In order to achieve this object, an operation control device for a DC motor according to the present invention comprises a rectifying section for converting an AC input voltage into two kinds of high and low DC voltages, and a plurality of semiconductor switches. Inverter circuit with bridge connection,
A DC motor driven by the inverter circuit, before
The rotation position of the DC motor rotor is detected and rotated.
Position detection circuit for generating rolling pulse, and the position detection circuit
Rotation speed detection circuit that counts the rotation pulse of
A rotation speed command circuit for commanding the rotation speed of the flow motor,
With the rotation speed command signal of the rotation speed command circuit and the rotation speed detection circuit
Duty to match the detected actual speed
A duty setting circuit that outputs a value, and a rectifying unit that selects a low DC voltage of the rectification unit when the rotation speed of the DC motor is low, and a high DC voltage of the rectification unit when the rotation speed of the DC motor is high. It has a configuration called a switching circuit.

The output of the duty setting circuit is used to check
Chopping signal that generates a signal to perform hopping
And a chopping signal correction circuit that corrects the chopping signal when switching the DC voltage of the rectification unit.

[0016]

With this configuration, the rectification switching circuit is
When the rotation speed of the DC motor is low, the low DC voltage conversion of the rectification unit is selected, and when the rotation speed of the DC motor is high, the high DC voltage conversion of the rectification unit is selected. As a result, the on ratio of the chopping duty can be increased even at a low rotation speed, so that the efficiency reduction at a low rotation speed can be suppressed.

By providing a chopping signal correction circuit, the chopping signal is corrected when the DC voltage conversion of the rectifying unit is switched. As a result, a temporary increase in the DC motor input current at the time of switching from the low DC voltage to the high DC voltage can be suppressed, so that the rotation speed can be smoothly switched and the parts can be downsized.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an operation control device for a DC motor according to a first embodiment of the present invention.

FIG. 1 is a block diagram of an operation control device for a DC motor, in which the same components as those of the conventional one are designated by the same reference numerals and detailed description thereof will be omitted.

Reference numeral 13 denotes a rectifying section switching circuit, which outputs a rectifying section switching signal'L 'to a rectifying section 14 which will be described later when the duty command of the duty setting circuit 9 is smaller than a predetermined minimum duty value d1. When the duty command is larger than the predetermined maximum duty value d2, the rectification unit switching signal'H 'is output to the rectification unit 14.

Reference numeral 14 is a rectifying unit, which converts an AC input voltage into a plurality of DC voltages. A detailed circuit of the rectification unit 14 is shown in FIG.

In FIG. 2, reference numeral 2 denotes a voltage doubler rectifier circuit, which has the same configuration as that shown in FIG. Reference numeral 15 is a rectifier circuit, which is composed of diodes 15a to 15d and a capacitor 15e. Needless to say, the rectifying unit 14 may be configured in other ways, and the circuit shown in FIG. 2 is an example.

Reference numerals 16 and 17 respectively denote an input switch and an output switch. As shown in (Table 1), when the rectifying section switching signal is "H", the input switch and the output switch are connected to the contacts 16a and 17a, respectively. Then, the voltage doubler rectifier circuit 2 rectifies the voltage. When the rectifying section switching signal is'L ', the input switch and the output switch are connected to the contacts 16b and 17b, respectively, and the rectifying circuit 15 performs rectification.

[0025]

[Table 1]

Next, the operation of the rectifying section switching circuit 13 and the rectifying section 14 will be described with reference to FIG.

First, in step 101, the duty setting circuit 9 compares the rotation speed command value of the rotation speed command circuit 7 with the rotation speed detection value of the rotation speed detection circuit 8, and the rotation speed detection value is small. For example, the process proceeds to step 102 and the duty value is increased.

Next, in step 103, the rectification section switching circuit 13 compares the duty value set in step 102 with the maximum duty value d2. If the set duty value is greater than or equal to d2, the process proceeds to step 104. , D2, the process returns to step 101. In step 104, the rectification switching circuit 13 outputs the rectification section switching signal'H ', the step-up voltage rectification circuit 2 of the rectification section 14 is selected in step 105, and the process returns to step 101 again.

Next, at step 101, if the rotation speed detection value is not small, the routine proceeds to step 106, and if the rotation speed detection value is large, the routine proceeds to step 107 to decrease the duty value. When the rotation detection value and the rotation speed command value are equal in step 106, the process returns to step 101 again.

Next, in step 108, the rectifying section switching circuit 13 compares the duty value set in step 107 with the minimum duty value d1. If the set duty value is less than or equal to d1, the process proceeds to step 109. If it is larger than d1, the process returns to step 101. In step 109, the rectifier switching circuit 13 outputs the rectifier switching signal'L ', the rectifier circuit 13 of the rectifier 14 is selected in step 110, and the process returns to step 101.

Therefore, the rectifying circuit 13 which outputs a low DC voltage when the rotation speed of the DC motor 4 is a low rotation speed is selected, and a high DC voltage is output when the rotation speed of the DC motor 4 is a high rotation speed. The voltage doubler rectifier circuit 2 that outputs
Will be selected.

As a result, the on ratio of the chopping duty can be increased even at a low rotation speed, so that it is possible to suppress a decrease in efficiency at a low rotation speed.

Next, a second embodiment of the present invention will be described with reference to the drawings.

FIG. 4 is a block diagram of an operation control device for a DC motor according to the second embodiment of the present invention.

Reference numeral 18 denotes a chopping correction circuit. When the duty command of the duty setting circuit 9 is equal to or more than the maximum duty value d2, the duty command is reduced to the minimum duty value d1 at a predetermined constant speed and correction is performed. As the duty command, the chopping signal generation circuit 10 and the rectification unit switching circuit 1
3 and outputs the corrected duty value to the chopping signal generation circuit 10 and the duty command of the duty setting circuit 9 to the rectifier switching circuit 13 when the corrected duty value becomes d1. Is.

Next, the operation of the chopping signal correction circuit 18 will be described with reference to FIG.

First, in step 201, the duty setting circuit 9 compares the rotation speed command value of the rotation speed command circuit 7 with the rotation speed detection value of the rotation speed detection circuit 8, and the rotation speed detection value is small. For example, the process proceeds to step 202 and the duty value is increased.

Next, in step 203, the rectifying section switching circuit 13 compares the duty value set in step 202 with the maximum duty value d2. If the set duty value is d2 or more, the process proceeds to step 204. , D2, the process returns to step 201.

In step 204, the chopping signal correction circuit 18 reduces the set duty value from the maximum duty value d2 at a predetermined constant speed, and outputs the correction duty command as the chopping signal generation circuit 10 and the rectification. It is output to the section switching circuit 13.

Next, in step 205, the chopping signal correction circuit 18 compares the correction duty value set in step 204 with the minimum duty value. If the correction duty value is d1 or less, the process proceeds to step 206, When it is larger than d1, the process returns to step 201. In step 206, the rectifying section switching circuit 13 outputs the rectifying section switching signal'H ', the doubling voltage rectifying circuit 2 of the rectifying section 14 is selected in step 207, and the process returns to step 201 again.

Next, at step 201, if the rotation speed detection value is not small, the routine proceeds to step 208, and if the rotation speed detection value is large, the routine proceeds to step 209 to decrease the duty value. When the rotation detection value is equal to the rotation command value in step 208, step 2 is executed again.
Return to 01.

Next, at step 210, the rectification section switching circuit 13 compares the duty value set at step 209 with the minimum duty value d1. If the set duty value is d1 or less, the routine proceeds to step 211. , D1, the process returns to step 201. In step 211, the rectifier switching circuit 13 outputs the rectifier switching signal'L ', the rectifier circuit 13 of the rectifier 14 is selected in step 212, and the process returns to step 101.

Therefore, when the rotation speed of the DC motor 4 is low, the rectifying circuit 13 which outputs a low DC voltage is selected, and when the rotation speed of the DC motor 4 is high, a high DC voltage is selected. The voltage doubler rectifier circuit 2 that outputs
Will be selected.

As a result, the on ratio of the chopping duty can be increased even at a low rotation speed, so that the efficiency reduction at a low rotation speed can be suppressed.

Further, the rectifying circuit 1 of the rectifying section 14
When switching 3 to the voltage doubler rectifier circuit 2, the chopping signal correction circuit 18 temporarily reduces the duty value, so that a temporary increase in the input current of the DC motor 4 at the time of switching can be suppressed. The rotation can be smoothly switched, and the parts can be downsized.

In the present embodiment, the rectification unit has been described as having two types of DC voltage conversion, but it goes without saying that the types of DC voltage conversion may be further increased.

[0047]

As described above, according to the present invention, the rectifying section switching circuit selects the low DC voltage of the rectifying section when the rotation speed of the DC motor is low, and selects the high DC voltage of the rectifying section when the rotation speed of the DC motor is high. Select the voltage. Therefore, the on ratio of the chopping duty can be increased even at a low rotation speed, so that the efficiency reduction at a low rotation speed can be suppressed.

Further, the chopping signal correction circuit corrects the chopping signal when switching the DC voltage of the rectifying section. As a result, a temporary increase in the DC motor input current at the time of switching from the low DC voltage to the high DC voltage can be suppressed, so that the rotation speed can be smoothly switched and the parts can be downsized.

[Brief description of drawings]

FIG. 1 is a block diagram of a DC motor operation control device according to a first embodiment of the present invention.

FIG. 2 is a detailed circuit diagram of the rectifying unit in FIG.

FIG. 3 is a flowchart showing the operation of the rectifier switching circuit and the rectifier of FIG.

FIG. 4 is a block diagram of an operation control device for a DC motor according to a second embodiment of the present invention.

5 is a flowchart showing the operation of the rectifier switching circuit and the rectifier of FIG.

FIG. 6 is a block diagram of a conventional DC motor operation control device.

[Explanation of symbols]

3 inverter 4 DC motor 6 Commutation circuit 10 Chopping signal generation circuit 11 Compositing circuit 12 drive circuit 13 Rectifier switching circuit 14 Rectifier 18 Chopping signal correction circuit

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-4-105583 (JP, A) JP-A-4-156291 (JP, A) JP-A-4-161090 (JP, A) JP-A-2- 79775 (JP, A) JP 58-54884 (JP, A) JP 61-170292 (JP, A) JP 56-150991 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H02P 6/06

Claims (2)

(57) [Claims] 1. A rectification unit for converting an AC input voltage into two types of high and low DC voltages, an inverter circuit in which a plurality of semiconductor switches are bridge-connected, a DC motor driven by the inverter circuit, and a DC motor of the DC motor. Rotor times
Position detection that detects rotation position and generates rotation pulse
Counts the rotation pulses of the output circuit and the position detection circuit
Rotation speed detection circuit and command the rotation speed of the DC motor
Rotation speed command circuit, and the rotation speed command of the rotation speed command circuit
Signal and the actual speed detected by the speed detection circuit
The duty setting that outputs the duty value so that
A constant circuit, and a rectifier switching circuit that selects a low DC voltage of the rectifier when the rotation speed of the DC motor is low, and selects a high DC voltage of the rectifier when the rotation speed of the DC motor is high. DC motor operation control device. Wherein a chopping signal generating circuit for generating a signal for chopper <br/> ping the output of the duty setting circuit, when switching the dc voltage of the rectifier unit, a chopping signal correction for correcting said chopping signal The operation control device for the DC motor according to claim 1, further comprising a circuit.