JPH08191589A - Brushless dc motor - Google Patents

Abstract

PURPOSE: To operate a motor at the maximum efficiency by detecting the relative rotational position of a stator and the rotor of the motor and by controlling the voltage pattern fo armature coils on the basis of a position signal. CONSTITUTION: A rotational position detector 3 detects the relative rotational position of a stator 1 and a rotor 10 on the basis of a potential difference between a voltage VN of the neutral point of armature coils 1a to 1c of a motor part 11 and a voltage VM of the neutral point of a resistance circuit 2 and outputs a position signal of which the level switches over at each 60deg . In order to control the speed of rotaion of the rotor 10 by changing the phase from the time point of the switchover of the position signal to the switchover of a voltage pattern, a microcomputer 4 outputs a command signal showing a phase correction angle, and based on the command signal, the phase from the time point of the switchover of the position signal to the switchover of the voltage pattern is corrected. Accordingly, the output voltage of an inverter part 20 can be made maximum at a rated point and further the execution of an operation with a larger output than the one at the rated point is also possible.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects a position signal representing the relative position of a rotor and a stator on the basis of an induced voltage induced in an armature coil of a brushless DC (direct current) motor, The present invention relates to a brushless DC motor that controls a voltage pattern of an armature coil based on the position signal.

[0002]

2. Description of the Related Art Conventionally, as a brushless DC motor,
There is one described in Japanese Examined Patent Publication No. 5-72197. As shown in FIG. 28, this brushless DC motor includes a rotor 70 having permanent magnets having a plurality of poles, a stator 71 having armature coils 71a, 71b and 71c connected in three phases Y, and the armature coil. A resistor circuit 72 including resistors 72a, 72b, 72c connected in parallel to 71a, 71b, 71c in a three-phase Y connection
And a rotational position detector 7 for detecting the relative rotational position of the rotor 70 with respect to the armature coils 71a, 71b, 71c.
3 and a position signal indicating the rotational position of the rotor 70 from the rotational position detector 73, the armature coils 71a, 7a
A microcomputer (hereinafter, referred to as a microcomputer) 74 that outputs a switching signal for switching the voltage pattern for the 1b and 71c, and a switching signal from the microcomputer 74 to switch and control the voltage pattern of the armature coils 71a, 71b, and 71c. A base drive circuit 75 that outputs a commutation control signal, and a commutation control signal from the base drive circuit 75, receive the armature coils 71a, 71b, 7
And an inverter unit 80 for switching the voltage pattern of 1c.

The inverter section 80 has three transistors 80a, 80b, 80c connected to the positive side of the DC power supply 76 via a switch 77 and three transistors 80d connected to the negative side of the DC power supply 76, respectively. , 80e, 8
It is composed of 0f. The collectors of the transistors 80a and 80d are connected to each other, the collectors of the transistors 80b and 80e are connected to each other, and the collectors of the transistors 80c and 80f are connected to each other. The transistors 80a and 80d
Of the transistors 80b and 80e are connected to the U-phase armature coil 71a, the transistors 80b and 80e are connected to the V-phase armature coil 71b, and the transistors 80c and 80f are connected to each other. Is connected to the W-phase armature coil 71c. Then, the commutation control signal from the base drive circuit 75 is input to the bases of the transistors 80a to 80f of the inverter section 80, respectively.

Further, the rotational position detector 73 includes a voltage V _{M at} the neutral point of the resistance circuit 72 and armature coils 71a, 7a.
The neutral point voltage V _{N of} 1b and 71c is input, and the resistance circuit 7
Neutral point of 2 and armature coils 71a, 71b, a differential amplifier 81 which outputs a voltage difference signal V _MN representing the voltage difference between the neutral point of 71c, receives a potential difference signal V _MN from the differential amplifier 81 , An integrator 82 for integrating the potential difference signal V _MN ,
A zero cross comparator 83 is provided which receives an integrated signal obtained by integrating the potential difference signal V _MN from the integrator 82 and outputs a position signal. Further, in the comparator 84, both ends of the armature coil 71c are connected to input terminals,
A signal indicating the polarity of the induced voltage E _W is output to the microcomputer 74.

In the brushless DC motor having the above structure, the motor terminal voltages of U-phase, V-phase, and W-phase from the inverter section 80 are V _U , V _V , V _W , and armature coils 71a, 71b, 7 respectively.
Each U-phase 1c, V-phase, the induced voltage E _U and W-phase, E _V, when the E _W, the voltage V _M at the neutral point of the resistor circuit 72 and the armature coil 7
1a, 71b, the voltage V _N at the neutral point of _{71c, V M = (1/3)} (V U + V V + V W) V N = (1/3) {(V U -E U) + (V _{V -E V) + (V W} -E
_W )}. Accordingly, the neutral point of the resistor circuit 72 and the armature coils 71a, 71b, the potential difference signal V _MN representing the voltage difference between the neutral point of 71c _{is, V MN = V M -V N} = (1/3) (E _U + E _V + E _W), and the armature coils 71a, 71b, the induced voltage E _U of 71c, E _V, is proportional to the sum of E _W.

The induced voltages E _U , E _V , and E _W of the armature coils 71a, 71b, and 71c are as shown in FIGS.
Become different in phase trapezoidal waveform for each 120 deg, the potential difference signal V _MN is induced voltage E _U, E _V, a substantially triangular wave having a fundamental frequency component of 3 times the E _W. The peak point of the triangular wave of the potential difference signal V _MN becomes the switching point of the voltage pattern. The integrator 82 integrates the potential difference signal V _MN from the differential amplifier 81 to generate a substantially sinusoidal integrated signal ∫V _MN dt.
(Shown in FIG. 29E) is output. Then, the zero-cross comparator 83 detects the zero-cross point of the integrated signal ∫V _MN dt and outputs the position signal (shown in FIG. 29 (F)) to the microcomputer 7.
4 is output. That is, the peak point of the voltage difference signal V _MN is the amplitude by the rotating speed is varied, by integrating the voltage difference signal V _MN, with each other to to detect the zero-cross point. The position signal indicates the relative position of the rotor 70 with respect to the armature coils 71a, 71b, 71c of the stator 71. Next, the microcomputer 74
Receives the position signal from the zero-cross comparator 83 and outputs a switching signal to the base drive circuit 75. The base drive circuit 75 receives the switching signal from the microcomputer 74 and sends a commutation control signal to the bases of the transistors 80a to 80f of the inverter unit 80 (FIG. 29 (G)).
~ (Shown in (L)) is output. Then, the inverter unit 8
The 0 transistors 80a-80f are sequentially turned on / off to switch the voltage pattern for the armature coils 71a, 71b, 71c.

Thus, the brushless DC motor is
Armature coils 71a, 71b, 71c of the induced voltage E _U, E _V, E _W
By detecting a position signal representing the rotational position of the rotor 70, the inverter unit 80 switches the voltage pattern of the armature coils 71a, 71b, 71c according to the position signal.

[0008]

By the way, when the brushless DC motor is used to drive a load such as a compressor having a large fluctuation range of torque, if the performance of the brushless DC motor is sufficiently exhibited, the compressor is It is possible to operate within the operation area (shown in FIG. 30) required by the. However, when the above-mentioned load is driven, the phase of the voltage pattern with respect to the induced voltage of the motor cannot be adjusted, so that there is a problem that the operation cannot be performed within the entire operation area.

Therefore, the applicant of the present application has conceived a brushless DC motor which can be operated in the entire operation area by correcting the phase of the voltage pattern while controlling the speed by the output voltage of the inverter section 80. This brushless DC motor is normally operated at a rated point within the operation area of the compressor shown in FIG. 31, and it is desirable that the motor efficiency be maximized at that rated point. However, as shown in FIG. 32, when the torque is constant at 20 kgfcm, the inverter output voltage becomes a characteristic line that rises to the right and gradually increases in proportion to the number of revolutions, and is rated to enable operation in all operating areas. At that point, the inverter output voltage becomes lower than the maximum voltage of 200V. For this reason, a large amount of motor current is supplied to produce the rated output, and as shown in FIG. 33, there is a problem that copper loss increases and motor efficiency decreases at the rated point, and the inverter output voltage becomes maximum at the rated point. It is necessary to use a motor that becomes. However, in this case, there arises a new problem that operation at an output higher than the rated point cannot be performed.

Therefore, an object of the present invention is to optimally switch between speed control by voltage and speed control by phase so that operation can be performed at maximum efficiency below the rated point and operation at an output higher than the rated point is also possible. To provide a motor.

[0011]

To achieve the above object, a brushless DC motor according to a first aspect of the present invention is a stator having a rotor having magnets having a plurality of poles and an armature coil connected to a three-phase Y connection. And a resistance circuit in which three-phase Y-connections are made in parallel with the armature coil, and a potential difference between a neutral point of the armature coil and a neutral point of the resistance circuit,
Based on the rotational position detecting means that detects the relative rotational position of the rotor and the stator and outputs a position signal whose level switches every 60 deg, and based on the position signal of the rotational position detecting means, In a brushless DC motor including an inverter section for switching the voltage pattern of an armature coil, a potential difference between a neutral point of the armature coil and a neutral point of the resistance circuit is detected, and a potential difference signal representing the potential difference is output. Potential difference detecting means, integrating means for integrating the potential difference signal detected by the potential difference detecting means, and outputting an integrated signal, and receiving the integrated signal from the integrating means, the level of the integrated signal is predetermined. A voltage command signal for controlling the rotation speed of the rotor by changing the output voltage of the inverter unit for determining whether the value is equal to or more than a value. In order to control the rotation speed of the rotor by changing the phase from the switching of the position signal to the switching of the voltage pattern, the voltage speed control means for outputting to the inverter section, and a command indicating the phase correction angle. Phase speed control means for outputting a signal, phase correction means for correcting the phase from the switching time of the position signal to the switching of the voltage pattern based on the command signal from the phase speed control means, and the voltage On the basis of the voltage command signal from the speed control means, when controlling the rotation speed by the voltage speed control means, when the output voltage of the inverter unit becomes the maximum voltage, the voltage speed control means changes to the phase speed control means. While switching the control of the rotation speed, when controlling the rotation speed by the phase speed control means, the level determination means When the level of the integration signal is determined to be less than the predetermined value, it is characterized in that a speed control switching means for switching the control of the rotational speed to the voltage speed control means from the phase speed control means.

Further, in the brushless DC motor according to claim 2, in the brushless DC motor according to claim 1, when the rotation speed is controlled by the voltage speed control means, when the predetermined value of the level determination means is at maximum efficiency. And the phase correction means switches the position signal based on the determination result of the level determination means such that the integrated signal from the integration means reaches the predetermined value. It is characterized in that the phase from the time point until the voltage pattern is switched is corrected.

According to a third aspect of the present invention, there is provided a brushless DC motor in which a rotor having magnets having a plurality of poles, a stator having an armature coil connected to a three-phase Y connection, and a parallel state with respect to the armature coil. The relative rotational position of the rotor and the stator is detected on the basis of the potential difference between the resistance circuit connected in three-phase Y-connection and the neutral point of the armature coil and the neutral point of the resistance circuit. And a brushless DC motor including a rotational position detecting unit that outputs a position signal whose level switches every 60 degrees, and an inverter unit that switches the voltage pattern of the armature coil based on the position signal of the rotational position detecting unit. In, the potential difference detection means for detecting the potential difference between the neutral point of the armature coil and the neutral point of the resistance circuit, and outputting a potential difference signal representing the potential difference,
Receiving the potential difference signal from the potential difference detecting means, level determining means for determining whether the level of the potential difference signal is a predetermined value or more, and changing the output voltage of the inverter section to change the rotation speed of the rotor. In order to control, the voltage speed control means for outputting a voltage command signal to the inverter section and the phase from the time when the position signal is switched to the time when the voltage pattern is switched are changed to control the rotation speed of the rotor. Therefore, based on the command signal from the phase speed control means, the phase speed control means for outputting a command signal representing the phase correction angle and the phase from the switching time of the position signal to the switching of the voltage pattern are determined. The rotation speed is controlled by the voltage speed control means based on the phase correction means for correction and the voltage command signal from the voltage speed control means. When the output voltage of the inverter section reaches the maximum voltage, the voltage speed control means switches the control of the rotation speed to the phase speed control means while the phase speed control means controls the rotation speed, When the determination means determines that the level of the potential difference signal is less than the predetermined value, the phase speed control means includes a speed control switching means for switching the control of the rotation speed to the voltage speed control means. .

According to a fourth aspect of the present invention, in the brushless DC motor of the third aspect, when the rotation speed is controlled by the voltage speed control means, when the predetermined value of the level determination means is at maximum efficiency. Of the potential difference signal, the phase correction means, based on the determination result of the level determination means, so that the potential difference signal from the potential difference detection means becomes the predetermined value,
It is characterized in that the phase from the time when the position signal is switched to the time when the voltage pattern is switched is corrected.

[0015]

According to the brushless DC motor of the first aspect, the rotational position detecting means causes the magnets having a plurality of poles to operate on the basis of the potential difference between the neutral point of the armature coil and the neutral point of the resistance circuit. The relative rotation position between the rotor and the stator that it has is detected, and a position signal whose level switches every 60 deg is output. The potential difference detecting means detects the potential difference between the neutral point of the armature coil and the neutral point of the resistance circuit and outputs a potential difference signal representing the potential difference, and the integrating means detects the potential difference detecting means. The potential difference signal from is integrated and the integrated signal is output. The voltage speed control means outputs a voltage command signal and changes the output voltage of the inverter section to control the rotation speed of the rotor. Then, when the output voltage of the inverter section becomes maximum, the speed control switching means switches the control of the rotational speed from the voltage speed control means to the phase speed control means. The phase speed control means outputs a command signal representing a phase correction angle in order to control the rotation speed of the rotor by changing the phase from the time when the position signal is switched to when the voltage pattern is switched, and the phase correction means The phase from the switching of the position signal to the switching of the voltage pattern is corrected based on the command signal indicating the phase correction angle. Then, when the integrated signal becomes less than the predetermined value based on the determination result of the level determination means, the speed control switching means switches the control of the rotation speed from the phase speed control means to the voltage speed control means. For example, by setting the inverter output voltage at the rated point of the motor to the maximum voltage, the motor is operated at the maximum efficiency at the rated point, and in the area where operation is possible by adjusting the inverter output voltage, the voltage speed control unit is used to adjust the voltage. Speed control by. On the other hand, in the operating region where the inverter output voltage becomes the maximum voltage and the rotation speed cannot be increased by the speed control by the voltage, the inverter output voltage is fixed at the maximum voltage and the phase speed control unit is used to control the speed by the phase. Performs field weakening control. That is, by advancing the phase of the output voltage of the inverter section further than the phase of the induced voltage, an armature current that weakens the field of the rotor is made to flow, and the induced voltage is apparently reduced to reduce the rotation speed. Raise it.

Therefore, the speed control can be smoothly switched by optimally switching the voltage speed control means and the phase speed control means. In addition, the output voltage of the inverter unit can be maximized at the rated point, and operation at an output higher than the rated point is possible.

According to the brushless DC motor of claim 2, in the brushless DC motor of claim 1,
When controlling the rotation speed by the voltage speed control means,
The predetermined value of the level determination means is set to the level of the integrated signal at the time of maximum efficiency, and the phase correction means,
Based on the determination result of the level determining means, the voltage pattern is switched from the switching point of the position signal so that the integrated signal from the integrating means becomes a predetermined value, that is, the motor is operated at maximum efficiency. Correct the phase up to.

Therefore, during speed control by the voltage of the voltage speed control means, the motor can be operated at maximum efficiency by correcting the phase of the output voltage of the inverter section by the phase correction means.

Further, according to the brushless DC motor of the third aspect, the rotational position detecting means has a plurality of poles based on the potential difference between the neutral point of the armature coil and the neutral point of the resistance circuit. The relative rotational position between the rotor having a magnet and the stator is detected, and a position signal for switching the level every 60 deg is output. Then, the potential difference detecting means detects a potential difference between the neutral point of the armature coil and the neutral point of the resistance circuit, and outputs a potential difference signal representing the potential difference. The voltage speed control means outputs a voltage command signal and changes the output voltage of the inverter section to control the rotation speed of the rotor. Then, when the output voltage of the inverter section becomes maximum, the speed control switching means switches the control of the rotational speed from the voltage speed control means to the phase speed control means. The phase speed control means outputs a command signal representing a phase correction angle in order to control the rotation speed of the rotor by changing the phase from the switching point of the position signal to the switching of the voltage pattern, and the phase correction means. Corrects the phase from the time when the position signal is switched to when the voltage pattern is switched, based on the command signal indicating the phase correction angle. Then, based on the determination result of the level determination means, when the potential difference signal becomes less than the predetermined value, the speed control switching means switches the control of the rotation speed from the phase speed control means to the voltage speed control means. For example, by setting the inverter output voltage at the rated point of the motor to the maximum voltage, the motor is operated at the maximum efficiency at the rated point, and in the area where operation is possible by adjusting the inverter output voltage, the voltage speed control unit is used to adjust the voltage. Speed control by. On the other hand, in the operating region where the inverter output voltage becomes the maximum voltage and the rotation speed cannot be increased by the speed control by the voltage, the inverter output voltage is fixed at the maximum voltage and the phase speed control unit is used to control the speed by the phase. Performs field weakening control.

Therefore, the speed control can be smoothly switched by optimally switching the voltage speed control means and the phase speed control means. In addition, the output voltage of the inverter unit can be maximized at the rated point, and operation at an output higher than the rated point is possible.

According to the brushless DC motor of claim 4, in the brushless DC motor of claim 3,
When controlling the rotation speed by the voltage speed control means,
The predetermined value of the level determining means is set to the level of the potential difference signal at the maximum efficiency, and the phase correcting means determines the potential difference signal from the potential difference detecting means based on the determination result of the level determining means. Is adjusted to a predetermined value, that is, the phase from the switching of the position signal to the switching of the voltage pattern is corrected so that the motor is operated at maximum efficiency.

Therefore, during speed control by the voltage of the voltage speed control means, the motor can be operated with maximum efficiency by correcting the phase of the output voltage of the inverter section by the phase correction means.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The brushless DC motor of the present invention will be described in detail below with reference to embodiments.

(First Embodiment) FIG. 1 shows the structure of a brushless DC motor according to a first embodiment of the present invention. Reference numeral 1 denotes a Y-connection of armature coils 1a, 1b, 1c, and a plurality of permanent magnets. A stator 2 for rotating the rotor 10 having a rotating magnetic field by a rotating magnetic field is connected in parallel to the armature coils 1a, 1b, 1c, and a resistor circuit in which resistors 2a, 2b, 2c are Y-connected, and 3 is the resistor circuit 2 Neutral point voltage V _M and armature coil 1a,
The potential difference signal V _MN indicating the potential difference from the neutral point voltage V _{N of} 1b and 1c is detected, and the relative position of the rotor 10 is detected based on the potential difference signal V _MN to detect the rotor 10 The rotational position detector as a rotational position detecting means for outputting a position signal indicating the relative position of the microcomputer 4, the microcomputer 4 receiving the position signal from the rotational position detector 3 and outputting a switching signal, the microcomputer 5 4 is a base drive circuit that receives a switching signal from the control circuit 4 and outputs a commutation control signal. Commutation control signals from the base drive circuit 5 are connected to the inverter section 20, respectively. The stator 1 and the rotor 10 form a motor unit 11.

The rotational position detector 3 inputs the neutral point voltage V _M of the resistance circuit 2 to the inverting input terminal, connects the ground GND to the non-inverting input terminal via the resistor R ₁ , and outputs the output terminal. and the resistance R ₂ and an amplifier IC1 connected to the capacitor C ₁ in parallel between the inverting input terminal, an inverting input terminal via the resistor R ₃ to the output terminal of the amplifier IC1 is connected to the non-inverting input terminal Ground GN via resistor R ₄
D together is connected, an amplifier IC2 where the resistor R ₅ is connected between the output terminal and the inverting input terminal, the amplifier IC2
The inverting input terminal is connected to the output terminal of, and the ground GND is connected to the non-inverting input terminal via the resistor R ₆ , and
And an amplifier IC3 of connecting the resistor R ₇ between the output terminal and the non-inverting input terminal. It has a structure which also serves as both of the amplifier IC1, resistor R _1, resistor R ₂ and the integrator 22 as a differential amplifier 21 and the integration means as a potential difference detecting means by the capacitor C _1. Further, an inverting amplifier 23 in the amplifier IC2 and resistors _{R 3, R 4, R 5} , amplifier I
In C3 and resistor R _6, R ₇ constitute a zero-cross comparator 24. Then, the armature coils 1a, 1b, 1c neutral point of because it is connected to the non-inverting input terminal of the amplifier IC1 via the ground GND and the resistor R _1, a differential amplifier 21
(Integrator 22), the voltage V _M and the armature coil 1a of the neutral point of the resistor circuit 2, 1b, and detects a potential difference signal V _MN representing the voltage difference between the voltage V _N at the neutral point of 1c, the potential difference Signal V _MN
Is integrated and an integrated signal ∫V _MN dt is output.

Further, the brushless DC motor includes a level detector 6 which receives the integrated signal ∫V _MN dt from the integrator 22 of the rotational position detector 3 and outputs a level detection signal to the microcomputer 4. As shown in FIG. 2, the level detector 6 connects the integrated signal ∫V _MN dt from the integrator 22 of the rotational position detector 3 to the inverting input terminal of the amplifier IC4, and also at the non-inverting input terminal of the amplifier IC4. To ground GND
Connected via a resistor R ₈ to connect the output terminal and the non-inverting input terminal of an amplifier IC4 via a resistor R _9. Constitute a hysteresis comparator having a hysteresis characteristic in the amplifier IC4 and the resistor R _8, R _9. The brushless DC motor is driven according to the position signal, and as shown in FIG. 4, the integrated signal ∫V _MN dt (shown in FIG. 4 (A)) input to the inverting input terminal of the amplifier IC4 of the level detector 6 is used as a reference. When the value E1 is exceeded, the output terminal of the amplifier IC4 becomes L level, and when the integrated signal ∫V _MN dt becomes less than the reference value E2,
The output terminal of the amplifier IC4 becomes H level. That is,
Level detection signal of the level detector 6 (shown in FIG. 4 (C))
Is a signal having the same period and a phase different from that of the position signal (shown in FIG. 4B). However, when the level of the integrated signal ∫V _MN dt from the rotational position detector 3 becomes small, the integrated signal ∫
V _MN may not exceed the reference value E1 is integral signal ∫V _MN dt
Does not fall below the reference value E2, the frequency of the level detection signal is lower than that of the position signal, and the duty ratio is different. That is, whether or not the integrated signal ∫V _MN is equal to or higher than a predetermined level can be detected by whether or not the level detection signal continues in a predetermined cycle.

The inverter section 20 includes three transistors 20a, 20b and 20c whose collectors are connected to the positive side of the DC power supply 9 and three transistors whose emitters are connected to the negative side of the DC power supply 9, respectively. 20d, 20e,
It is composed of 20f. The emitter of the transistor 20a and the collector of the transistor 20d are connected to each other, and the emitter of the transistor 20b and the transistor 20e are connected.
Are connected to each other, and the emitter of the transistor 20c and the collector of the transistor 20f are connected to each other. The U-phase armature coil 1a is connected to the mutually connected portions of the transistors 20a and 20d, and the V-phase armature coil 1b is connected to the mutually connected portions of the transistors 20b and 20e. The W-phase armature coil 1c is connected to the mutually connected portions of 20f. Then, diodes are respectively connected in antiparallel between the collectors and the emitters of the transistors 20a to 20f.

As shown in FIG. 3, the microcomputer 4 further includes a phase correction timer T1 to which the position signal from the rotational position detector 3 shown in FIG. 1 is connected via an external interrupt terminal, and the position signal. In response, the period measurement timer T2 for measuring the period of the voltage pattern of the armature coils 1a, 1b, 1c and the measured timer value from the period measurement timer T2 are received, and the armature coil 1a is obtained from the timer value. , 1b, 1c calculates the period of the voltage pattern and outputs a period signal representing the period, and the period signal from the period calculating unit 41 is received, and the period corresponds to the phase correction angle. And a timer value calculator 42 for calculating a timer value and outputting a timer value setting signal to the phase correction timer T1. Further, the microcomputer 4 receives a periodic signal from the period calculating unit 41, calculates a rotation speed and outputs a current speed signal, and a current speed signal from the speed calculating unit 43 and an external signal. And a voltage speed control unit 44 as a voltage speed control means for receiving the speed command signal and outputting a voltage command signal.
A phase speed control unit 45 as a phase speed control means for receiving a current speed signal from the speed calculation unit 43 and a speed command signal from the outside and outputting a phase correction angle command signal, and an interrupt from the phase correction timer T1. An inverter mode selection unit 46 that receives the signal IRQ and outputs a voltage pattern signal, and a PWM that receives the voltage pattern signal from the inverter mode selection unit 46 and the voltage command signal from the voltage speed control unit 44 and outputs a switching signal (Pulse width modulation) section 47. The voltage command signal from the voltage speed control unit 44 is connected to the input 1 of the switch SW2, the voltage command signal of the maximum voltage is connected to the input 2 of the switch SW2, and the voltage command signal from the voltage speed control unit 44 and the maximum voltage are connected. Either one of the voltage command signals is input from the switch SW2 to the PWM unit 47. The phase correction timer T1, the cycle measuring timer T2, the cycle calculating section 41, and the timer value calculating section 42 constitute phase correcting means.

Further, the microcomputer 4 receives the position signal from the rotational position detector 3 and the level detection signal from the level detector 6 and outputs a level determination signal and a phase correction angle command signal representing the level determination result. A level determination unit 51 for outputting is provided, a phase correction angle command signal from the level determination unit 51 is connected to the input 1 of the switch SW1, and a phase correction angle command signal from the phase speed control unit 45 is connected to the input 2 of the switch SW1. Then, one of the phase correction angle command signal from the level determination unit 51 and the phase correction angle command signal from the phase speed control unit 45 is input to the timer value calculation unit 42 from the switch SW1. It should be noted that the level detector 6 and the level determination section 51 constitute a level determination means.

Further, the microcomputer 4 receives the voltage command signal from the voltage speed control unit 44 and the level judgment signal indicating the level judgment result from the level judgment unit 51, and performs speed control by voltage and speed control by phase. A speed control switching determination unit 52 for determining switching is provided, and the speed control switching determination unit 52 uses the switch SW in the case of speed control by voltage.
While switching 1 and SW2 to the input 1 side, switches SW1 and SW2 are switched to the input 2 side in the case of speed control by phase. The speed control switching determination unit 52 and the switches SW1 and SW2 constitute speed control switching means.

In the above structure, when the brushless DC motor is driven according to position detection, the induced voltages E _U , E _V , E _{W of the} U-phase, V-phase and W-phase of the armature coils 1a, 1b, 1c.
Shows a trapezoidal waveform having different phases every 120 deg, as shown in FIGS. The amplifier IC1 of the rotational position detector 3 shown in FIG. 1 has the voltage V _{M at} the neutral point of the resistor circuit 2 input to the inverting input terminal and the armature coil input to the non-inverting input terminal of the amplifier IC1. Potential difference signal V _MN (Fig. 5) representing the potential difference from the neutral point voltage V _N of 1a, 1b, 1c.
(Shown in (D)), the potential difference signal V _MN is integrated, and an integrated signal ∫V _MN dt (shown in FIG. 5E) is output. The integrated signal ∫V _MN dt has a substantially sinusoidal waveform having a frequency three times the rotation frequency. Then, the inverting amplifier 23
Amplifies the integrated signal ∫V _MN dt input to the inverting input terminal of the amplifier IC2 to a predetermined amplitude, and the zero-cross comparator 24 detects the zero-cross of the amplified integrated signal ∫V _MN dt and detects the position signal. (Shown in FIG. 5 (F)) is output.

Next, the position signal from the rotational position detector 3 is sent from the external interrupt terminal of the microcomputer 4 to the cycle measuring timer T.
Entered in 2. Then, the period measuring timer T2 measures the period from the leading edge to the trailing edge and the period from the trailing edge to the leading edge of the position signal, and outputs the measured timer value. In response to the signal representing the timer value from the cycle measuring timer T2, the cycle calculating section 41 causes the armature coils 1a, 1b,
Find the period of the voltage pattern of 1c. That is, the period from the trailing edge to the leading edge and the period from the leading edge to the trailing edge of the position signal are repeated every 60 deg, and the measured timer value of each period is multiplied by 6 to obtain the above voltage. The timer value for one cycle of the pattern is obtained.

Then, in response to the periodic signal representing the period from the period calculating unit 41, the timer value calculating unit 42 outputs the timer value setting signal. Upon receiving the timer value setting signal from the timer value calculation unit 42, the phase correction timer T1 measures the time until the voltage signal is switched from the position signal. That is, the phase correction timer T1 causes the inverter mode selection unit 46 to receive the interrupt signal I when the count ends.
The RQ is output, and the inverter mode selection unit 46 outputs the phase-corrected voltage pattern signal (shown in FIGS. 5H to 5M) to the PW.
It is output to the M section 47. Then, the PWM unit 4
Reference numeral 7 denotes a base drive circuit 5 which shows a switching signal in FIG.
Then, when the base drive circuit 5 outputs a commutation control signal to the inverter section 20, each of the transistors 20a to 20f of the inverter section 20 is turned on / off. Note that FIG.
The inverter mode shown in (N) is the voltage pattern signal (FIG. 5 (H)-
(Shown in (M)), numbers 0 to 5 are assigned.

The operation of the microcomputer 4 will be described below with reference to FIGS.
It will be described according to the flowcharts 8 and 9. It should be noted that the interrupt processing 1 is performed every time the position signal input to the external interrupt terminal of the microcomputer 4 rises or falls. The reference values E1 and E2 of the level detector 6 are set to values corresponding to the level V1 of the integrated signal ∫V _MN dt at the maximum motor efficiency point. Before starting the interrupt processing 1, switch SW
1, SW2 is selected on the input 1 side to perform speed control by voltage and clear the counters CNT1 and CNT2.

First, in FIG. 6, when the interrupt processing 1 starts, it is determined in step S101 whether or not the previous level detection signal is at the H level. If it is determined that the previous level detection signal is at the H level, the process proceeds to step S111. , It is determined whether or not the level detection signal this time is L level. When it is determined in step S111 that the current level detection signal is at the L level, the process proceeds to step S112, the counter CNT1 is incremented by 1, and the process proceeds to step S102. On the other hand, if it is determined in step S111 that the current level detection signal is not the L level, the process proceeds to step S102.

On the other hand, if it is determined in step S101 that the previous level detection signal is not at the H level, the process proceeds to step S113 to determine whether or not the current level detection signal is at the H level.
When it is determined in step S113 that the current level detection signal is at the H level, the process proceeds to step S114, the counter CNT1 is incremented by 1, and the process proceeds to step S102. On the other hand, if it is determined in step S113 that the current level detection signal is not the H level, the process proceeds to step S102.

Next, in step S102, the counter CNT2 is incremented by 1, and in step S103, it is determined whether or not the counter CNT2 is 5, and if it is determined that the counter CNT2 is 5, the process proceeds to step S121 while the counter is counted. CNT2
If it is determined that is not 5, the process proceeds to step S104. Then, in step S121, it is determined whether or not the counter CNT1 is 5, and when it is determined that the counter CNT1 is 5,
If the level of the integrated signal ∫V _MN dt exceeds the level V1 at the peak efficiency point, the process proceeds to step S122, and the process proceeds to step S126. On the other hand, in step S121, the counter CNT1
If it is determined that the counter CNT1 is not 5, it proceeds to step S123 and determines whether or not the counter CNT1 is 0. When it is determined in step S123 that the counter CNT1 is 0, the process proceeds to step S124, where it is assumed that the level of the integrated signal ∫V _MN dt is below the peak efficiency point level V1, and the process proceeds to step S126. On the other hand, in step S123, the counter CN
If it is determined that the content of T1 is not 0, the process proceeds to step S125, the integrated signal ∫V _MN dt is determined to have the optimum level, and the process proceeds to step S126. Next, in step S126, the counter CN
T1 is cleared, the counter CNT2 is cleared in step S127, and the process proceeds to step S104.

Next, in step S104, the period measurement timer T2
The timer value is read, the process proceeds to step S105, the period measurement timer T2 is started, and the next period measurement is started. Then, in step S106, the cycle calculator 41 calculates the cycle of the position signal from the timer value of the cycle measuring timer T2,
The speed calculator 43 calculates the motor rotation frequency (current speed).

Next, in step S107, it is determined whether the current speed control is voltage speed control. If it is determined that the voltage speed control is in voltage speed control, the operation proceeds to step S131 where error frequency = command frequency-rotation. Calculate the frequency. The command frequency is based on a speed command signal from the outside, and the rotation frequency is based on the current speed calculated by the speed calculator 43. Next, in step S132, it is determined whether the error frequency is 0 or more, and when it is determined that the error frequency is 0 Hz or more, the process proceeds to step S141, and Bufpa = Kpa × error frequency is calculated. However, Kpa is a coefficient. Next, in step S142, Bufia (current time) = Bufia (previous time) + Kia × error frequency is calculated. However, Kia is a coefficient. Next, in step S143, the voltage command Vreq = Bufia + Bufpa (current time) is calculated, and the process proceeds to step S133.

On the other hand, if it is determined in step S132 that the error frequency is negative, the flow advances to step S144 to calculate Bufpa = Kpa × error frequency. However, Kpa is a coefficient. Next, in step S145, Bufia (current time) = Bufia (previous time) −Kia × error frequency is calculated. However, Kia is a coefficient. Next, in step S146, the voltage command Vreq = Bufia-Bufpa (this time) is calculated, and the process proceeds to step S133, in which the voltage speed control unit 4 is operated.
4 outputs the voltage command Vreq.

Next, in step S134, it is determined whether or not the level is optimal, and if it is determined that the level is optimal, the process proceeds to step S135, while if it is determined that the level is not optimal, the process proceeds to step S151 and the integrated signal It is determined whether the level of ∫V _MN dt exceeds the level V1 of the peak efficiency point. When it is determined in step S151 that the level of the integrated signal ∫V _MN dt is higher than the level V1, the process proceeds to step S152, the previous phase correction angle command is set to +1 deg (delay correction side), and the process proceeds to step S135. On the other hand, if it is determined in step S151 that the level of the integrated signal ∫V _MN dt does not exceed the level V1, the process proceeds to step S153, the previous phase correction angle command is set to −1 deg (advance correction side), and the process proceeds to step S135.

Next, in step S135, the timer value calculator 42 determines the phase correction timer value T based on the phase correction angle command.
Calculate ISOU. Next, in step S136, the phase correction timer value TISOU (which is timer 1 in FIG. 7) is set in the phase correction timer T1, and the phase correction timer T1 is started in step S137.

Next, in step S138, it is determined whether or not the voltage command is the maximum voltage, and if it is determined that the voltage command is the maximum voltage, the process proceeds to step S154, and the speed control is switched to the phase control, and this division is performed. Include processing 1 ends. That is, the speed control switching determination unit 52 switches the switch SW.
1, SW2 is switched from the input 1 side to the input 2 side, PWM
The voltage command signal of the maximum voltage is input to the unit 47 via the switch SW2 to maximize the output voltage of the inverter unit 20 and the phase correction angle command signal of the phase speed control unit 45 is input via the switch SW1 to the timer calculation unit. It is input to 42 and speed control is performed by the phase of the voltage pattern.

On the other hand, if it is determined in step S138 that the voltage command is not the maximum voltage, the interrupt processing 1 is ended.

On the other hand, when it is determined in step S107 that the voltage / speed control is not performed, the process proceeds to step S161 shown in FIG. 8 and error frequency = command frequency-rotation frequency is calculated. Next, in step S162, the error frequency is 0 Hz.
If it is determined that the error frequency is 0 or more, it proceeds to step S171 to calculate Bufpb = Kpb × error frequency. However, Kpb is a coefficient. Next, in step S172, Bufib (current time) = Bufib (previous time) −Kib × error frequency is calculated. However, Kib is a coefficient. Next, in step S173, the phase command Preq = Bufib-Bufpb (current time) is calculated, and the process proceeds to step S163.

On the other hand, if it is determined in step S162 that the error frequency is negative, the flow advances to step S174 to calculate Bufpb = Kpb × error frequency. However, Kpb is a coefficient. Next, in step S175, Bufib (current time) = Bufib (previous time) + Kib × error frequency is calculated. However, Kib is a coefficient. Next, in step S176, the phase command Preq = Bufib + Bufpb (current time) is calculated, and the flow proceeds to step S163.

Next, in step S163, the phase correction angle command Pr
The phase correction timer value TISOU is calculated from eq. next,
In step S164, the PWM unit 4 outputs the voltage command signal of the maximum voltage.
Type in 7. Next, in step S165, the phase correction timer value TI is set in the phase correction timer T1 (timer 1 in FIG. 8).
SOU is set, and the phase correction timer T1 is started in step S166. Then, in step S167, it is determined whether or not the level of the integrated signal ∫V _MN dt is below the level V1 at the peak efficiency point, and it is determined that the level of the integrated signal ∫V _MN dt is below the level V1. Then, step S1
Proceeding to 78, the speed control is switched to the voltage, and this interrupt processing 1 is ended. That is, the speed control switching determination unit 52 switches the switches SW1 and SW2 to the input 1 side, the voltage command signal from the voltage speed control unit 44 is input to the PWM unit 47 via the switch SW2, and the inverter unit 2
The output voltage of 0 is adjusted to control the speed by voltage, and the phase correction angle command signal from the level determination unit 51 is input to the timer calculation unit 42 via the switch SW1 to adjust the phase of the voltage pattern. The maximum motor efficiency operation is performed.

On the other hand, in step S167, the integrated signal ∫V _MN dt
When it is judged that the level of is not below the level V1,
This interrupt processing 1 is completed.

Further, as shown in FIG. 9, when the count of the phase correction timer T1 is finished and the interrupt signal IRQ is output from the phase correction timer T1, the inverter mode is advanced by one step in step S181. Next, in step S182, the voltage pattern is output, and this interrupt processing 2 is ended.

FIGS. 5 (A) to 5 (N) show signals of respective parts of this brushless DC motor. The brushless DC motor operates according to the flowcharts of FIGS. 6 to 9,
As shown in FIG. 5 (G), the phase correction timer T1 starts sequentially for each position signal. Then, for example, when the inverter mode (shown in FIG. 5 (N)) is [4], the phase correction timer T1 is started with the switching point of the position signal as the reference point, and the phase correction timer T1 finishes counting. At that point, the inverter mode is advanced one step to [5].

As described above, every time the interrupt processing 1 is performed five times, it is determined whether the level detection signal continuously changes from the H level to the L level and from the L level to the H level, and the level is detected. When it is determined that the change in the detection signal has continued five times, it is determined that the level of the integrated signal ∫V _MN dt is equal to or higher than a predetermined value (based on the reference values E ₁ and E ₂ of the level detector 6), while the level detection signal is If it is determined that there has not been any change in, the level of the integrated signal ∫V _MN dt is assumed to be less than the predetermined value. Also,
When the change of the level detection signal is 1 to 4 times, the level of the integrated signal ∫V _MN dt is stable near a predetermined value and is an optimum level.

Then, when speed control by voltage is performed, when the level of the integrated signal ∫V _MN dt is equal to or higher than a predetermined value,
While the phase of the voltage pattern is delayed by 1 deg, the phase of the voltage pattern is advanced by 1 deg when the level of the integrated signal ∫V _MN dt is less than a predetermined value. Therefore, by setting the above-mentioned predetermined value to the level of the integrated signal ∫V _MN dt at the peak efficiency point, the phase of the voltage pattern is corrected so that the level of the integrated signal ∫V _MN dt becomes the predetermined value, and the maximum value is obtained. Motor efficient operation can be performed. Then, when the rotation frequency is increased by the voltage-based speed control and the voltage command becomes maximum, the speed control is switched to the phase-based speed control.

On the other hand, when the speed control based on the phase is performed, the voltage command is always maximized, the phase correction angle is corrected to control the rotation frequency, and the level of the integrated signal ∫V _MN dt becomes less than the predetermined value. At this time, it switches to speed control by voltage.

Therefore, as shown in FIG. 10, in a motor having a rated speed of 80 rpm and a torque of 20 kgfcm, the inverter output voltage is maximized at the rated point to maximize the motor efficiency at the rated point. You can Then, the maximum motor efficiency control area (speed control area by voltage) is an area shown by the shaded area in FIG. 10, and the field weakening control area (speed control area by phase) is an area adjacent to the upper right corner of the maximum motor efficiency control area. Become. The boundary line between the maximum motor efficiency control region and the field weakening control region shows when the inverter output voltage is the maximum voltage in the speed control by voltage.

FIG. 11 shows the torque of 20 kgfc in FIG.
The relationship between the rotation speed and the inverter output voltage when m is constant is shown. In the region where the rotation speed is 0 rps to approximately 80 rps, the maximum motor efficiency in which the inverter output voltage increases from 0 V to the maximum voltage 200 V in proportion to the rotation speed. Becomes the control area,
In the region where the rotation speed exceeds 80 rps, the inverter output voltage is fixed at the maximum voltage of 200 V and becomes the field weakening control region.

FIG. 12 shows the relationship between the number of revolutions at a constant torque and the motor efficiency. The inverter output voltage is the maximum voltage and the motor efficiency is the maximum at the rated point where the number of revolutions is about 80 rps.

FIG. 13 shows the relationship between the phase correction angle and the rotation speed when the speed is controlled by the phase with the torque being constant. When the phase correction angle is set to the delay correction side, the rotation speed becomes smaller, When the phase correction angle is advanced to the correction side, the rotation speed increases. In the field-weakening control region of FIG. 10, when the rotational speed is reduced from the state of operating at a torque of 20 kgfcm and a rotational speed of 110 rps to the rated point, the phase correction angle is controlled to the delayed phase side, and the maximum motor efficiency point is exceeded. Also, if the speed control is not switched to the voltage, the motor will reach the step-out limit point and step out. Therefore, as shown in the relationship between the phase correction angle and the integration signal ∫V _MN dt during voltage speed control (when the speed is constant) shown in FIG. 14, the level of the integration signal ∫V _MN dt increases as the phase correction angle becomes closer to the delay correction side. Becomes smaller and the phase correction angle advances, and the level of the integrated signal ∫V _MN dt increases as it goes to the correction side. When speed control is performed by voltage, the level of the integrated signal ∫V _MN dt at the maximum motor efficiency point becomes V almost constant
Using the characteristic of 1, the speed control by phase is switched to the speed control by voltage. That is, during speed control by the phase, since it is on the lead correction side with respect to the phase of the maximum motor efficiency point, the level of the integrated signal ∫V _MN dt is greater than V1, and the phase correction angle is set on the delay correction side, and the rotation speed is changed. while reducing the level of the integral signal ∫V _MN dt is monitored by the level determining unit 51, when the level of the integral signal ∫V _MN dt becomes V1, by switching the speed control by the voltage, the speed control by the phase It smoothly switches to speed control by voltage.

For example, as shown in FIG. 15, in the field weakening control region within the operation area of the compressor, the torque is increased from the rated point A to the point B, and the rotational speed is kept constant with the torque kept constant. The speed is lowered to shift to the point C where the speed control is switched to the voltage. At this time, the integrated signal ∫V _MN
As shown in FIG. 16, at the rated point A, the level of dt becomes the level V1 of the peak efficiency point of the phase correction angle φ2, and the region having a level higher than V1 is the field weakening control region. Then, when the torque is increased from the rated point A, the substantially straight line representing the characteristic of the integrated signal ∫V _MN dt moves substantially in parallel to the advance correction side, and accordingly moves to the point B having a value larger than the level V1. Next, a transition is made from point B to point C of the phase correction angle φ1 along a substantially straight line representing the characteristic of the integrated signal ∫V _MN dt.

Further, as shown in FIG. 17, in the field weakening control region within the operation area of the compressor, the rotational speed is increased from the rated point A to the point B, and the torque is maintained while the rotational speed is kept constant. The speed is lowered to shift to the point C where the speed control is switched to the voltage. At this time, the level of the integrated signal ∫V _MN dt becomes the level V1 at the peak efficiency point of the phase correction angle φ2 at the rated point A, as shown in FIG. 18, and the region having a level higher than V1 is the field weakening control region. Is. Then, if the rotation speed is increased from the rated point A, the integrated signal ∫V _MN dt
Along the substantially straight line representing the characteristic of, the point B is shifted to a value larger than the level V1. Next, when the torque is reduced from point B, the substantially straight line representing the characteristic of the integrated signal ∫V _MN dt moves substantially parallel to the delay correction side, and accordingly, the phase correction angle φ3
To the point C of level V1.

Therefore, by optimally switching the speed control by voltage and the speed control by phase, the output voltage of the inverter unit can be maximized at the rated point, and the motor can be operated at maximum efficiency at the rated point.

In the case of speed control by voltage, the phase correction means corrects the phase of the inverter output voltage so that the level of the integrated signal ∫V _MN dt becomes the level V1 of the peak efficiency point, and the motor is driven. Can be operated with maximum efficiency.

(Second Embodiment) FIG. 19 is a block diagram showing the essential parts of a brushless DC motor according to a second embodiment of the present invention.
The brushless DC motor, the microcomputer, and the level detector have the same configuration, and the drawings and description are omitted except for the microcomputer 100 and the level detectors 6A, 6B ,. 20 shows a block diagram of the microcomputer 100 of the brushless DC motor. The microcomputer 100 of this brushless DC motor receives the current speed signal and the torque signal from the speed calculating unit 43 and the other components other than the level determining unit 51 of the microcomputer 4 of the first embodiment, and outputs a switching signal. In response to the level detection signal switching unit 101 and the switching signal from the level detection signal switching unit 101, the level detector 6A,
Switch S for switching the level detection signal from 6B, ...
W3, and a level determination unit 102 that receives a level detection signal from the switch SW3 and a position signal from the rotational position detector 3 and outputs a signal indicating a level determination result.

21 and 22, the brushless DC motor of the second embodiment has different characteristics from the brushless DC motor of the first embodiment as described below.

First, FIG. 21 shows the characteristics of the integrated signal ∫V _MN dt with respect to the phase correction angle when the operating frequency is fixed and the load is changed in the brushless DC motor. The characteristic of the brushless DC motor is that the integrated signal ∫V _MN dt changes from the lead correction side of the phase correction angle to the delay correction side.
The level becomes gradually smaller and becomes closer to the lead correction side of the phase correction angle as the load increases, while it moves substantially parallel from the lead correction side of the phase correction angle to the delay correction side as the load decreases. When the load is large, the phase correction angle at the peak efficiency point is φ5, and the level of the integrated signal ∫V _MN dt at this phase correction angle φ5 is V2. On the other hand, when the load is small, the phase correction angle at the peak efficiency point is φ6, and the level of the integrated signal ∫V _MN dt at this phase correction angle φ6 is V3.

FIG. 22 shows the characteristics of the integral signal ∫V _MN dt with respect to the phase correction angle when the operating frequency is changed while the load is kept constant in the brushless DC motor. The characteristic of the brushless DC motor is that the integrated signal ∫V _MN dt changes from the lead correction side of the phase correction angle to the delay correction side.
Is gradually reduced, and the higher the operating frequency is, the closer the phase correction angle is to the advance correction side, while the lower the operating frequency is, the phase correction angle is advanced from the advance correction side to the delay correction side substantially in parallel. When the operating frequency is high, the phase correction angle at the peak efficiency point is φ7, and the level of the integrated signal ∫V _MN dt at this phase correction angle φ7 is V4. On the other hand, the phase correction angle at the peak efficiency point was φ8 when the operating frequency was low, and the level of the integrated signal ∫V _MN dt at this phase correction angle φ8 was V5.

That is, the present invention is applied to a brushless DC motor in which the level of the integrated signal at the peak efficiency point does not become constant depending on the magnitude of the load and the level of the operating frequency.

In the brushless DC motor having the above structure, the position signal from the rotational position detector 3 and the speed calculation unit 4 are used.
The level detection signal switching unit 101 outputs a switching signal to the switch SW3, based on the current speed signal from No. 3 and the torque signal representing the torque value according to the load from the outside.
That is, one of the level detectors 6A, 6B, ... Is selected according to the change of the load and the change of the operating frequency, and the reference value for judging the level of the integrated signal ∫V _MN dt is switched. After that, the microcomputer 100 executes the first
The interrupt processing shown in the flowcharts of FIGS. 6, 7, 8 and 9 of the embodiment is performed. Therefore, switching from speed control by voltage to speed control by phase is performed when the output voltage of the inverter unit 20 is maximum, while switching from speed control by phase to speed control by voltage is integrated by the load or the rotation frequency. Even if the level of the signal ∫V _MN dt changes, the integrated signal is monitored based on the reference value according to the load and the rotation frequency, and is performed when the level of the integrated signal ∫V _MN dt falls below the reference value.

Therefore, the output voltage of the inverter can be maximized at the rated point, and the motor can be operated at maximum efficiency at the rated point.

Further, in the case of speed control by voltage, the phase of the inverter output voltage is corrected by the phase correction means so that the level of the integrated signal ∫V _MN dt becomes the reference value selected according to the load and the operating frequency. By doing so, the motor can be operated with maximum efficiency.

Although the level detectors 6A, 6B, ... Determine the level of the integrated signal in the second embodiment, it may determine the level of the potential difference signal.

That is, as shown in FIG. 23, in the brushless DC motor, the characteristic of the potential difference signal with respect to the phase correction angle is shown when the load is kept constant and the operating frequency is changed. The characteristic of the brushless DC motor is a substantially straight line in which the level of the potential difference signal gradually decreases from the advance correction side of the phase correction angle to the delay correction side, and the higher the operating frequency is, the closer the phase correction angle is to the advance correction side. As the frequency is lower, the phase correction angle moves substantially parallel to the lag correction side from the lead correction side. When the operating frequency was high, the phase correction angle at the peak efficiency point was φ3, and the level of the potential difference signal at this phase correction angle φ3 was V2.
On the other hand, when the operating frequency is low, the phase correction angle at the peak efficiency point is φ3, and the level of the potential difference signal at this phase correction angle φ3 is V22. Note that the phase correction angle φ13 is a step out limit point, and the step out limit level when the operating frequency is high is V
3. The step-out limit level is V23 when the operating frequency is low. Based on the characteristic of the potential difference signal, one of the level detectors 6A, 6B, ... Is selected according to the change of the operating frequency to switch the reference value for determining the level of the potential difference signal. Good.

(Third Embodiment) FIG. 24 is a block diagram of a microcomputer used in the brushless DC motor of the third embodiment of the present invention, except for the brushless DC motor, the microcomputer and the level detector shown in FIG. A / D converter 20 having the same configuration and replacing the microcomputer 200 and the level detector
Illustrations and explanations other than 2 are omitted. The rotational position detector 3
The A / D converter 202 receives the integrated signal from
The converted integrated signal is output.

Further, the microcomputer 200 of the brushless DC motor described above receives a position signal from the rotational position detector 3, a current speed signal from the speed calculation unit 43, a torque signal representing an external load torque value, and A / A. A level determination unit 201 that receives the A / D-converted integrated signal from the D converter 202 and outputs a signal representing the level determination result is provided. In the brushless DC motor, the level of the integrated signal at the peak efficiency point does not become constant depending on the size of the load and the operating frequency, as in the second embodiment.

In the brushless DC motor having the above structure, the level determination unit 201 selects a reference value from a preset table based on the current speed signal from the speed calculation unit 43 and the torque signal from the outside, It is determined whether or not the peak value of the A / D-converted integrated signal is greater than or equal to the reference value. Then, the interrupt process shown in the flowcharts of FIGS. 6, 7, 8 and 9 of the first embodiment is performed. Therefore, switching from voltage speed control to phase speed control is
While the output voltage of the inverter unit 20 is maximum,
Switching from speed control by phase to speed control by voltage monitors the integrated signal based on the reference value according to the load and rotation frequency even if the level of the integration signal ∫V _MN dt changes depending on the load and rotation frequency. Then, when the level of the integrated signal ∫V _MN dt falls below the reference value.

Therefore, the output voltage of the inverter section can be maximized at the rated point, and the motor can be operated at maximum efficiency at the rated point.

Further, in the case of speed control by voltage, the phase of the inverter output voltage is corrected by the phase correcting means so that the level of the integrated signal ∫V _MN dt becomes the reference value selected according to the load and the operating frequency. By doing so, the motor can be operated with maximum efficiency.

In the first, second and third embodiments, the phase correction angle is adjusted so that the level of the integrated signal becomes a predetermined value, and the maximum efficiency operation is performed. It may be set to a value.

Further, in the above-mentioned first, second and third embodiments, the phase correcting timer T1 and the period measuring timer T are used as the phase correcting means.
Although the period calculation unit 41 and the timer value calculation unit 42 are used, the phase correction means is not limited to this.

Although the microcomputers 4, 100, 200 are used in the first, second, and third embodiments, logic circuits or the like may be used instead of the microcomputers.

In the first, second and third embodiments, the voltage pattern switching method of the armature coils 1a, 1b, 1c is the 180-degree energization method, but the voltage pattern switching is limited to 180 degrees. Instead, a 120-180 degree energization method may be used.

Further, in the first, second and third embodiments, the rotational position detector 3 is used as the rotational position detecting means, but the rotational position detecting means is not limited to this, and other circuit configurations may be used. Of course.

That is, as shown in FIG. 25, the neutral point voltage V _M of the resistor circuit 2 is connected to the inverting input terminal, and the resistor R ₂₁ is connected between the non-inverting input terminal and the ground GND. , A resistor R ₂₂ is provided between the output terminal and the inverting input terminal.
An amplifier IC21 where the capacitor C ₂₁ is connected in parallel with,
Inverting input terminal to the output terminal of the amplifier IC21 is connected, the resistor R ₂₃ between the non-inverting input terminal and the ground GND
There is connected, or may be that having an amplifier IC22 are connected a resistor R ₂₄ between the output terminal and the non-inverting input terminal.

Further, as shown in FIG. 26, the neutral point voltage V _M of the resistor circuit 2 is connected to the inverting input terminal, and the resistor R ₃₁ is connected between the non-inverting input terminal and the ground GND. , the output terminal and the amplifier IC31 of resistance R ₃₂ is connected between the inverting input terminal, is connected to the inverting input terminal via the output terminal and the resistor R ₃₃ of the amplifier IC31, and a non-inverting input terminal and the ground GND A resistor R ₃₄ is connected between the amplifier IC 32 and a resistor R ₃₅ and a capacitor C ₃₁ are connected in parallel between the output terminal and the inverting input terminal, and an inverting input terminal is provided at the output terminal of the amplifier IC 32. A resistor R ₃₆ may be connected between the non-inverting input terminal and the ground GND, and a resistor R ₃₇ may be connected between the output terminal and the non-inverting input terminal to include the amplifier IC 33. .

As shown in FIG. 27, the armature coils 1a, 1b, 1c are Y-connected, and the stator 1 for rotating a rotor 10 having a plurality of permanent magnets by a rotating magnetic field and the armature coil 1a. , 1b, 1c connected in parallel, and a resistor circuit 2 in which resistors 2a, 2b, 2c are Y-connected, and a DC power source 10
Three transistors 20a respectively connected to the positive side of 9
20b, 20c and three transistors 20d, 20e, 20f respectively connected to the negative side of the DC power supply 109, and a brushless provided with an inverter unit 20 in which the emitters of the transistors 20d, 20e, 20f are connected to the ground GND. In a DC motor, armature coils 1a, 1b, 1c
The neutral point voltage V _N is connected to the inverting input terminal via the resistor R ₄₁ , the neutral point voltage V _{M of} the resistors 2a, 2b, 2c is connected to the non-inverting input terminal, and the non-inverting input terminal is also connected. An amplifier IC 41 in which a resistor R ₄₂ is connected between the terminal and the ground GND and a resistor R ₄₃ is connected between the output terminal and the inverting input terminal.
When, the output terminal of the amplifier IC41 and via the resistor R ₄₄ is an inverting input terminal connected, the non-inverting input terminal and ground GN
A resistor R ₄₅ is connected to D and an amplifier IC _{42 in} which a resistor R ₄₆ and a capacitor C ₄₁ are connected in parallel between an output terminal and an inverting input terminal, and an inversion to the output terminal of the amplifier IC _42. The input terminal is connected, the resistor R ₄₇ is connected between the non-inverting input terminal and the ground GND, and the resistor R ₄₈ is connected between the output terminal and the non-inverting input terminal to provide the amplifier IC43. The ones are good.

In the first embodiment, the differential amplifier 21 of the rotational position detector 3 is used as the potential difference detecting means, and the integrator 2 is used.
Although 2 is used as the integrating means, the potential difference detecting means and the integrating means may be configured separately from the rotational position detector.

In the third embodiment, the integrated signal ∫V
_MN dt is A / D converted, but the potential difference signal or the signal obtained by smoothing the potential difference signal or the integrated signal ∫V _MN dt is subjected to A / D conversion, and the level is obtained by using the A / D converted signal. You may make a decision.

[0087]

As is apparent from the above, the brushless DC motor according to the invention of claim 1 has a rotor having magnets having a plurality of poles, and a stator having an armature coil connected to a three-phase Y connection. Three-phase Y in parallel with the armature coil
Based on the connected resistance circuit and the potential difference between the neutral point of the armature coil and the neutral point of the resistance circuit, the relative rotational position of the rotor and the stator is detected to obtain 60 deg.
A brushless DC motor comprising: a rotational position detecting unit that outputs a position signal whose level switches every time; and an inverter unit that switches a voltage pattern of the armature coil based on the position signal of the rotational position detecting unit,
The potential difference detecting means detects the potential difference between the neutral point of the armature coil and the neutral point of the resistance circuit and outputs a potential difference signal representing the potential difference, and the integrating means detects the potential difference detected by the potential difference detecting means. The signal is integrated, the integrated signal is output, the integrated signal from the integrating means is received, and the level determining means determines whether or not the level of the integrated signal is equal to or more than a predetermined value,
The voltage speed control unit outputs a voltage command signal to the inverter unit in order to change the output voltage of the inverter unit and control the rotation speed of the rotor, while the phase speed control unit,
In order to control the rotation speed of the rotor by changing the phase from the time when the position signal is switched to when the voltage pattern is switched, a command signal indicating the phase correction angle is output, and the phase correction means switches the position signal. The phase from the time point until the voltage pattern is switched is corrected based on the command signal from the phase speed control means, and the speed control switching means is rotated by the voltage speed control means based on the voltage command signal from the voltage speed control means. When controlling the speed, when the output voltage of the inverter unit reaches the maximum voltage, the control of the rotation speed is switched from the voltage speed control means to the phase speed control means, while the level determination means is used when the rotation speed is controlled by the phase speed control means. If it is determined that the level of the integrated signal is less than the predetermined value, the phase speed control means switches the rotation speed control to the voltage speed control means. It is obtain things.

Therefore, according to the brushless DC motor of the first aspect of the invention, the speed control can be smoothly switched by optimally switching the voltage speed control means and the phase speed control means. In addition, the output voltage of the inverter unit can be maximized at the rated point, and operation at an output higher than the rated point is possible.

Further, in the brushless DC motor according to the invention of claim 2, in the brushless DC motor according to claim 1, when the rotation speed is controlled by the voltage speed control means, the predetermined value of the level determination means is set to the maximum efficiency. The phase correction means sets the position signal of the position signal so that the integration signal from the integration means has the predetermined value based on the determination result of the level determination means. The phase from the time of switching to the switching of the voltage pattern is corrected.

Therefore, according to the brushless DC motor of the second aspect of the present invention, at the time of speed control by the voltage of the voltage speed control means, the phase correction means corrects the phase of the output voltage of the inverter section to maximize the efficiency. The motor can be operated with.

Further, the brushless DC motor according to the invention of claim 3 has a rotor having a magnet having a plurality of poles, a stator having an armature coil connected to a three-phase Y connection, and the armature coil. The relative rotational positions of the rotor and the stator are determined based on the potential difference between the resistance circuit in which the three-phase Y-connections are connected in parallel and the neutral point of the armature coil and the neutral point of the resistance circuit. A brushless device that includes a rotational position detection unit that detects and outputs a position signal whose level switches every 60 degrees, and an inverter unit that switches the voltage pattern of the armature coil based on the position signal of the rotational position detection unit. In the DC motor, the potential difference detecting means is
The potential difference signal representing the potential difference is detected by detecting the potential difference between the neutral point of the armature coil and the neutral point of the resistance circuit, and the level determination means receives the potential difference signal from the potential difference detection means and receives the potential difference signal. The voltage speed control means outputs a voltage command signal to the inverter part in order to change the output voltage of the inverter part to control the rotation speed of the rotor. The phase speed control means outputs a command signal representing a phase correction angle in order to control the rotation speed of the rotor by changing the phase from the time when the position signal is switched to when the voltage pattern is switched, and the phase correction means , The phase from the position signal switching time to the voltage pattern switching is corrected based on the command signal from the phase speed control means, and based on the voltage command signal from the voltage speed control means. Then, the speed control switching means switches the control of the rotation speed from the voltage speed control means to the phase speed control means when the output voltage of the inverter section reaches the maximum voltage when the rotation speed is controlled by the voltage speed control means, while the phase control is performed. When controlling the rotation speed by the speed control means,
When the level determination means determines that the level of the potential difference signal is less than the predetermined value, the phase speed control means switches the control of the rotation speed to the voltage speed control means.

Therefore, according to the brushless DC motor of the third aspect of the present invention, the speed control can be smoothly switched by optimally switching the voltage speed control means and the phase speed control means. In addition, the output voltage of the inverter unit can be maximized at the rated point, and operation at an output higher than the rated point is possible.

Further, in the brushless DC motor of the fourth aspect of the present invention, in the brushless DC motor of the third aspect, when the rotation speed is controlled by the voltage speed control means, the predetermined value of the level determination means is set to the maximum efficiency. At the level of the potential difference signal at the time of, the phase correction means,
Based on the determination result of the level determination means, the phase from the switching point of the position signal to the switching of the voltage pattern is corrected so that the potential difference signal from the potential difference detection means becomes the predetermined value. is there.

Therefore, according to the brushless DC motor of the fourth aspect of the present invention, at the time of speed control by the voltage of the voltage speed control means, the phase correction means corrects the phase of the output voltage of the inverter section to maximize the efficiency. The motor can be operated with.

[Brief description of drawings]

FIG. 1 is a brushless D according to a first embodiment of the present invention.
It is a block diagram of a C motor.

FIG. 2 is a circuit diagram of a level detector of the brushless DC motor.

FIG. 3 is a block diagram of a microcomputer of the brushless DC motor.

FIG. 4 is a diagram showing signals of respective parts when the level detector is used.

FIG. 5 is a diagram showing signals of respective parts of the brushless DC motor.

FIG. 6 is a flowchart showing an interrupt processing 1 of the above microcomputer.

FIG. 7 is a flowchart showing an interrupt process 1 of the microcomputer.

FIG. 8 is a flowchart showing an interrupt processing 1 of the microcomputer.

FIG. 9 is a flowchart showing an interrupt process 2 by a timer interrupt of the phase correction timer of the microcomputer.

FIG. 10 is a diagram showing an operating area of the compressor when the compressor is driven as a load of the brushless DC motor.

FIG. 11 is a diagram showing a characteristic of an inverter output voltage with respect to a rotation speed of the brushless DC motor.

FIG. 12 is a diagram showing characteristics of motor efficiency with respect to the rotation speed of the brushless DC motor.

FIG. 13 is a diagram showing a characteristic of a rotation frequency with respect to a phase correction angle in the brushless DC motor.

FIG. 14 is a diagram showing a characteristic of an integrated signal with respect to a phase correction angle in the brushless DC motor.

FIG. 15 is a diagram showing a transition of an operating state in the above brushless DC motor when speed control by voltage is switched to speed control by phase, and further speed control is switched by voltage.

FIG. 16 is a diagram showing a relationship of an integration signal with respect to a phase correction angle when the speed control by voltage is switched to the speed control by phase and further the speed control by voltage is switched in the brushless DC motor.

FIG. 17 is a diagram showing a transition of an operating state when the speed control by voltage is switched to the speed control by phase and further the speed control by voltage is switched in the brushless DC motor.

FIG. 18 is a diagram showing a relationship of an integration signal with respect to a phase correction angle when the speed control by voltage is switched to the speed control by phase in the brushless DC motor, and further the speed control is switched by voltage.

FIG. 19 is a configuration diagram of essential parts of a brushless DC motor according to a second embodiment of the present invention.

FIG. 20 is a block diagram of a microcomputer of the brushless DC motor.

FIG. 21 is a diagram showing the characteristics of the integrated signal with respect to the phase correction angle when the load is changed at a constant frequency in the brushless DC motor.

FIG. 22 is a diagram showing a characteristic of an integrated signal with respect to a phase correction angle when the frequency is changed with a constant load in the brushless DC motor.

FIG. 23 is a diagram showing a characteristic of a potential difference signal with respect to a phase correction angle when the frequency is changed with a constant load in the brushless DC motor.

FIG. 24 is a block diagram of a brushless DC motor microcomputer according to a third embodiment of the present invention.

FIG. 25 is a circuit diagram of another example of a rotational position detector.

FIG. 26 is a circuit diagram of a rotation position detector of another example.

FIG. 27 is a circuit diagram of another example of a rotational position detector.

FIG. 28 is a configuration diagram of a conventional brushless DC motor.

FIG. 29 is a diagram showing signals of respective parts of the brushless DC motor.

FIG. 30 is a diagram showing an operation area of the compressor when the compressor is driven as a load of the brushless DC motor.

FIG. 31 is a diagram showing an operating area of the compressor when the compressor is driven as a load of the brushless DC motor.

FIG. 32 is a diagram showing a characteristic of an inverter output voltage with respect to a rotation speed of the brushless DC motor.

FIG. 33 is a diagram showing characteristics of motor efficiency with respect to the rotation speed of the brushless DC motor.

[Explanation of symbols]

1 ... Stator, 1a, 1b, 1c ... Armature coil, 2 ... Resistance circuit, 3 ... Rotation position detector, 4 ... Microcomputer, 5 ... Base drive circuit, 6 ... Level detector, 9 ... DC power supply, 10 ... Rotor, 20 ... Inverter section, 20a-20f ... Transistor, 41 ... Period computing section, 42 ... Timer value computing section, 43 ...
Speed calculation unit, 44 ... Voltage speed control unit, 45 ... Phase speed control unit, 46 ... Inverter mode selection unit, 47 ... PWM
Section, 51 ... Level determination section, 52 ... Speed control switching determination section,
T1 ... Phase correction timer, T2 ... Period measurement timer.

Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H02P 6/02 371 J

Claims (4)

[Claims] 1. A rotor (10) having a multi-pole magnet,
A stator (1) having an armature coil (1a, 1b, 1c) connected to a three-phase Y connection, and the armature coil (1a, 1b, 1c)
And a resistor circuit (2) with three-phase Y connection in parallel,
Based on the potential difference between the neutral point of the armature coils (1a, 1b, 1c) and the neutral point of the resistance circuit (2), the rotor (1
0) and the relative rotational position of the stator (1) are detected,
Based on the rotational position detecting means (3) that outputs a positional signal whose level switches every 60 degrees, and the armature coils (1a, 1b, 1) based on the positional signal of the rotational position detecting means (3).
In a brushless DC motor including an inverter section (20) for switching the voltage pattern of c), the potential difference between the neutral point of the armature coils (1a, 1b, 1c) and the neutral point of the resistance circuit (2) is set. A potential difference detecting means (21) for detecting and outputting a potential difference signal representing the potential difference, and an integrating means (22) for integrating the potential difference signal detected by the potential difference detecting means (21) and outputting an integrated signal.
And a level determining means (6, 51) for receiving the integrated signal from the integrating means (22) and determining whether the level of the integrated signal is a predetermined value or more, and an output of the inverter section (20). Voltage speed control means for outputting a voltage command signal to the inverter section (20) in order to control the rotation speed of the rotor (10) by changing the voltage.
(44) and, in order to control the rotation speed of the rotor (10) by changing the phase from the switching point of the position signal to the switching of the voltage pattern, a command signal indicating a phase correction angle is output. The phase speed control means (45) and the phase from the time when the position signal is switched to when the voltage pattern is switched are the phase speed control means (45).
Correction means for correcting based on the command signal from
(T1, T2, 41, 42) and the voltage command signal from the voltage speed control means (44), when the rotation speed is controlled by the voltage speed control means (44), the inverter section (20 When the output voltage of) becomes the maximum voltage, the rotational speed control is switched from the voltage speed control means (44) to the phase speed control means (45), while the rotational speed is controlled by the phase speed control means (45). At this time, if the level determination means (6, 51) determines that the level of the integrated signal is less than the predetermined value,
From the phase speed control means (45) to the voltage speed control means
Speed control switching means for switching the rotation speed control to (44)
A brushless DC motor having (52, SW1, SW2). 2. The brushless DC motor according to claim 1, wherein when the rotation speed is controlled by the voltage speed control means (44), the predetermined value of the level determination means (6) is set to the maximum efficiency. Set to the level of the integrated signal above,
The phase correction means (T1, T2, 41, 42) is based on the determination result of the level determination means (6), and the integration means (2
2. A brushless DC motor characterized in that the phase from the switching of the position signal to the switching of the voltage pattern is corrected so that the integrated signal from 2) becomes the predetermined value. 3. A rotor (10) having a multi-pole magnet,
A stator (1) having an armature coil (1a, 1b, 1c) connected to a three-phase Y connection, and the armature coil (1a, 1b, 1c)
And a resistor circuit (2) with three-phase Y connection in parallel,
Based on the potential difference between the neutral point of the armature coils (1a, 1b, 1c) and the neutral point of the resistance circuit (2), the rotor (1
0) and the relative rotational position of the stator (1) are detected,
Based on the rotational position detecting means (3) that outputs a positional signal whose level switches every 60 degrees, and the armature coils (1a, 1b, 1) based on the positional signal of the rotational position detecting means (3).
In a brushless DC motor including an inverter section (20) for switching the voltage pattern of c), the potential difference between the neutral point of the armature coils (1a, 1b, 1c) and the neutral point of the resistance circuit (2) is set. A potential difference detecting means (21) for detecting and outputting a potential difference signal representing the potential difference, and the potential difference signal from the potential difference detecting means (21) are received to determine whether the level of the potential difference signal is a predetermined value or more. A level determining means for determining and a voltage speed for outputting a voltage command signal to the inverter part (20) in order to control the rotation speed of the rotor (10) by changing the output voltage of the inverter part (20). Control means
(44) and, in order to control the rotation speed of the rotor (10) by changing the phase from the switching point of the position signal to the switching of the voltage pattern, a command signal indicating a phase correction angle is output. The phase speed control means (45) and the phase from the time when the position signal is switched to when the voltage pattern is switched are the phase speed control means (45).
Correction means for correcting based on the command signal from
(T1, T2, 41, 42) and the voltage command signal from the voltage speed control means (44), when the rotation speed is controlled by the voltage speed control means (44), the inverter section (20 When the output voltage of) becomes the maximum voltage, the rotational speed control is switched from the voltage speed control means (44) to the phase speed control means (45), while the rotational speed is controlled by the phase speed control means (45). At this time, when the level determination means determines that the level of the potential difference signal is less than the predetermined value, the speed control switching for switching the rotation speed control from the phase speed control means (45) to the voltage speed control means (44). Means (52, S
W1 and SW2)
C motor. 4. The brushless DC motor according to claim 3, wherein when the voltage speed control means (44) controls the rotation speed, the predetermined value of the level determination means is set to:
The potential difference signal level at the maximum efficiency is set, and the phase correction means (T1, T2, 41, 42) sets the potential difference detection means (2) based on the determination result of the level determination means.
So that the potential difference signal from 1) becomes the predetermined value,
A brushless DC motor, which corrects a phase from the time when the position signal is switched to when the voltage pattern is switched.