JPH0538184A - Brushless motor drive - Google Patents

Abstract

(57) [Abstract] [Purpose] To realize a brushless motor drive device without using a switching power supply (DC / DC converter) or the like in a drive device of a brushless motor used for driving home appliances and consumer appliances. With the goal. [Structure] A rotor position detection circuit 3, a plurality of drive coils, an energization state command circuit 4, a frequency generator 36, a speed detection circuit 5, a phase comparator 31, and a switching power element which constitutes a power circuit is turned on. By providing the PWM circuit 13 for controlling the ON / OFF duty and the means for applying a constant DC voltage to the power circuit, it is possible to maintain a constant power without using a switching power supply or the like which was conventionally required to change the rotation speed. Even if the DC voltage is directly applied to the motor, it is possible to obtain a highly accurate brushless motor drive device capable of variable speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless motor driving device.

[0002]

2. Description of the Related Art Conventionally, AC motors have been widely used as driving motors for home electric appliances such as air conditioners and water heaters and consumer appliances. A fan motor for an air conditioner or a water heater needs a variable speed to adjust its air volume. However, the AC motor has an advantage that it is very easy to use because it can be directly connected to and driven by an AC power source of a commercial power source, but it is difficult to change its rotation speed. Therefore, in recent years, a DC brushless motor that can easily change the rotation speed has been widely used instead of the AC motor. An example thereof is shown in FIG. FIG. 5 is a circuit diagram of a conventional brushless motor driving device.

A conventional brushless motor driving device will be described below with reference to FIG. The position detection circuit 106 obtains the output signal of the position detection sensor 105 and outputs the position detection signal of the rotor. The energization switching circuit 107 outputs an energization switching signal for the drive coil of the motor based on the position detection signal. This energization switching signal is power-amplified by the power circuit 108 to sequentially switch the energization state of the drive coil to drive the motor. The commercial power supply 102 is the rectifying / smoothing circuit 1
The DC voltage is rectified and smoothed by 03 to drive the switching power supply (DC / DC converter), and the DC voltage applied to the power circuit is changed by the switching power supply to change the rotation speed of the motor.

[0004]

However, in the brushless motor drive device having the above-described structure, a switching power supply (DC / DC converter) or the like is required to change the rotation speed of the motor. Since many elements such as coils, capacitors, and resistors are required to configure a switching power supply, a large amount of mounting space is required when configuring the system, and it is difficult to make the system light and thin, and it is costly. It was a factor to increase the price.

In view of the above problems, the present invention can change the rotation speed of a motor without using a switching power supply even when a constant DC voltage is applied to a power supply terminal of a power circuit, and a speed command. (EN) Provided is a high-performance and space-saving brushless motor drive device capable of obtaining a rotation speed synchronized with a signal.

[0006]

In order to achieve this object, a brushless motor driving device of the present invention is a position detecting device for detecting a rotational position of a plurality of phase coils of a motor and a rotor driven by the driving coil. Circuit, an energization state command circuit that sequentially switches energization states of the drive coil based on a position detection signal output from the position detection circuit, a frequency generator that detects a signal proportional to a rotation speed, and the frequency power generation A speed detection circuit that outputs a speed signal of a motor based on a detection signal from the machine, a speed command circuit of the motor, and a phase of the speed signal from the speed detection circuit and the speed command signal from the speed command circuit. O of a phase comparator to be compared and a switching power element forming a power circuit for supplying electric power to the drive coil according to a phase error signal from the phase comparator. / OFF to control the duty PW
It has an M circuit and a means for applying a DC voltage to the power circuit.

[0007]

According to the present invention, the AC power supply voltage can be rectified and smoothed to the DC power supply voltage and directly applied to the power supply terminal of the power circuit by the above-mentioned structure, and the motor rotation can be performed accurately in synchronization with the speed command signal without using the switching power supply. The speed can be variably controlled.

[0008]

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

1 and 2 are circuit diagrams of a brushless motor driving device according to an embodiment of the present invention. 1 and 2
Together, they constitute an embodiment of the configuration of the present invention.

Now, 1a, 1b and 1c are drive coils, which are connected to the power circuit 9. Position detection sensor 2
The output signals of a, 2b, and 2c are input to the position detection circuit 3, and the output signal of the position detection circuit 3 is input to the energization state command circuit 4. Reference numeral 36 is a frequency generator, for example, a zigzag FG drawn on a printed circuit board as shown in the figure.
An FG magnet connected to the rotor is provided so as to face the pattern, and a frequency signal corresponding to the rotation speed of the motor is obtained. Further, as another configuration of the frequency generator, a method of providing an FG magnet facing a Hall element, a Hall IC, a magnetic resistance element, or the like can be considered. A speed detection circuit 5 amplifies the detection signal from the frequency generator 36 and outputs a rectangular wave speed signal via a hysteresis comparator. A speed command circuit 6 outputs a rectangular wave-shaped speed command signal via a photocoupler and a hysteresis comparator. Reference numeral 31 is a phase comparator which compares the phases of the speed command signal and the speed signal and outputs a phase error signal corresponding to the phase difference. The phase error signal is converted into a DC voltage by the phase error amplifier 33 and input to one input terminal of the PWM comparator 35. Reference numeral 34 is an oscillator that oscillates at a constant frequency, and its output voltage is input to the other input terminal of the PWM comparator 35. The PWM comparator 35 compares the voltages of the two inputs, and outputs a PWM signal whose ON / OFF duty changes according to the phase error. In the PWM circuit 13, the energization state command circuit 4
The PWM signal is superposed on the output signal from the input terminal and is input to the base of the drive transistor forming the power circuit 9. The DC voltage applying means 12 is directly connected to the power circuit 9.

The specific circuit operation of the brushless motor driving device having the above-described structure according to the embodiment of the present invention will be described below.

FIG. 3 is a diagram of operation signal waveforms in FIG. 1, in which V _A , V _B and V _C are rotor position detection signal waveforms. The position detection signal is logically processed by the energization state command circuit 4 as follows, and the energization state command signal UHo,
Obtain VHo, WHo, UL, VL, WL.

UHo: Logical product of V _A and INV V _B V Ho: Logical product of V _B and INV V _C W Ho: Logical product of V _C and INV V _A UL: Logical product of V _B and INV V _A VL: V Logical product of _C and INV V _B WL: Logical product of V _A and INV V _C where INV V _A , INV V _B , INV V _C are inverted signals of V _A , V _B and V _C , respectively.

These energization state command signals are shown in FIG.
UHo, VHo, WHo, UL, VL, WL.

In FIG. 3, Vd is a duty control circuit 7
Is an output signal and is an ON / OFF signal. V
The d is logically processed by the energization switching circuit 8 as follows, and energization switching signals UH, VH, WH, UL, VL and WL are obtained.

UH: logical product of UHo and Vd VH: logical product of VHo and Vd WH: logical product of WHo and Vd UL: UL VL: VL WL: WL Applied to. For example, when UH and VL are H, current flows from the U-phase drive coil to the V-phase drive coil, and when UH and WL are H, current flows from the U-phase drive coil to the W-phase drive coil. In this way, the excitation states of the drive coils are switched one after another and the motor rotates. Also, V
By controlling the ON time of d, the current flowing through the drive coil can be controlled and the speed of the motor can be varied.

Next, the variable speed means of the motor will be described. FIG. 4 is an operation signal waveform diagram of the PWM circuit 13 in FIG. F _ref is an output signal of the speed command circuit 6, that is, a speed command signal, and F _SP is an output signal of the speed detection circuit 5, that is, a speed signal. The phase of the rising edge of each of the speed command signal and the speed signal is the phase comparator 31.
Are compared and output as both phase error signals PD. The phase error signal PD is converted into a DC voltage signal V _TH by the phase error amplifier 33. On the other hand, oscillator 3
4 outputs a triangular wave signal V _OSC which oscillates at a constant frequency and a constant amplitude. The signals V _TH and V _OSC are PW
The voltage is compared by the M comparator 35, and its output becomes a rectangular wave signal having ON / OFF duty such as Vd ′.

By the way, when the rotation speed of the motor becomes faster than the speed command signal F _ref , the speed signal F _SP is changed as shown in FIG.
, The H section of the position error signal PD becomes shorter and the potential of the signal V _TH decreases. At this time, since the ON time of the output voltage Vd 'of the PWM comparator 35 decreases and the motor current decreases, the rotation speed of the motor decreases, and as a result, the speed command signal F _ref and the speed signal F _SP become equal in frequency, and It is controlled so that the phase difference between the two signals is kept constant.

On the contrary, when the rotation speed of the motor becomes slower with respect to the speed command signal F _ref , the circuit operation opposite to the above is performed, and similarly, the frequency of the speed command signal F _ref and the frequency of the speed signal F _SP . Are equalized and the phase difference between the two signals is controlled to be constant. That is, the motor can be accurately controlled to a rotational speed synchronized with the speed command signal F _ref, moreover the speed command signal F _ref
The rotation speed of the motor can be easily changed by changing the.

Since the speed command signal is a digital signal,
Signals can be exchanged using elements such as photocouplers, and the motor control system and motor drive system are insulated, and noise generated from the motor drive system has an adverse effect on the motor control system. You can avoid it.

[0021]

As described above, according to the present invention, a DC voltage obtained by rectifying and smoothing an AC voltage of a commercial power source is directly applied to a power circuit for supplying electric power to a drive coil of a motor, and a signal proportional to a rotation speed is applied. Equipped with a frequency generator for detecting, the phase difference between the speed signal and the speed command signal from the speed detection circuit that outputs the speed signal based on the detection signal from the frequency generator is detected by the phase comparator, By providing a PWM circuit that controls the ON / OFF duty of the switching power element that constitutes the power circuit according to the phase error signal, the motor can be operated according to the speed command signal without using a switching power supply as in the past. You can shift. Moreover, the coils, capacitors, resistors, etc., which were conventionally required to configure the switching power supply, are not required, and the space for the motor drive system is reduced,
It can be simplified and the cost of parts can be reduced. Further, since the speed signal detected from the frequency generator is phase-locked with respect to the speed command signal, the rotation speed can be controlled to be constant with extremely high accuracy, and the rotation speed can be easily changed by changing the speed command signal. Can be changed. Furthermore, since the speed command signal can be isolated by a photocoupler, noise generated from the motor drive system can be prevented from adversely affecting the motor control system. A drive device can be realized.

[Brief description of drawings]

FIG. 1 is a divided view of a circuit configuration diagram of a brushless motor drive device according to an embodiment of the present invention.

FIG. 2 is a divided diagram of a circuit configuration diagram of a brushless motor drive device according to an embodiment of the present invention.

FIG. 3 is a waveform diagram of an operation signal in FIG.

FIG. 4 is an operation signal waveform diagram of the PWM circuit in FIG.

FIG. 5 is a block diagram of a conventional brushless motor drive device.

[Explanation of symbols]

 1a, 1b, 1c Drive coil 2a, 2b, 2c Position detection sensor 3 Position detection circuit 4 Energization state command circuit 5 Speed detection circuit 6 Speed command circuit 7 Duty control circuit 8 Energization switching circuit 9 Power circuit 10 AC power supply voltage 11 Rectification smoothing Circuit 12 DC voltage applying means 13 PWM circuit 31 Phase comparator 33 Phase error amplifier 34 Oscillator 35 PWM comparator 36 Frequency generator

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuji Dohi 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Sosei Yamamoto, 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co.

Claims (3)

[Claims] 1. A drive coil based on a plurality of phase coils of a motor, a position detection circuit for detecting a rotational position of a rotor driven by the drive coil, and a position detection signal output from the position detection circuit. An energized state command circuit for sequentially switching the energized state of, a frequency generator that detects a signal proportional to the rotation speed, a speed detection circuit that outputs a speed signal of the motor based on the detection signal from the frequency generator, A speed command circuit of the motor, a phase comparator for comparing the phases of the speed signal from the speed detection circuit and the speed command signal from the speed command circuit, and the drive according to the phase error signal from the phase comparator. A PWM circuit that controls the ON / OFF duty of a switching power element that constitutes a power circuit for supplying power to the coil, and a constant DC voltage is applied to the power circuit. Brushless motor driving device comprising and means for. 2. The brushless motor drive device according to claim 1, wherein a voltage obtained by rectifying and smoothing a commercial power source is directly applied to the power circuit. 3. The PWM circuit outputs an output signal from an energization state command circuit that sequentially switches the energization states of the drive coils based on the position detection signal and a voltage obtained by converting the phase error signal from the phase comparator into a DC voltage. The output voltage of the oscillation circuit that oscillates at a constant frequency is compared, and ON / OF
The brushless motor drive device according to claim 1 or 2, wherein an output signal from the duty control circuit in which the F duty changes is superimposed.