JP2001186793A - Dc brushless motor device and compressor using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem associated with a DC brushless motor device that a request to ignite applied voltage ahead of the zero cross point of induced voltage to accomplish high-efficiency operation or high-r.p.m. revolution cannot be met. SOLUTION: The DC brushless motor device has a plurality of phases and its revolution is controlled by an inverter. The motor device is provided with the inverter 2 that energizes each phase in the DC brushless motor according to control signals, a position detecting means 4 that detects the rotational position of the DC brushless motor based on a reference signal, and a control means 5 that outputs control signals to the inverter based on the result of position detection by the position detecting means. The reference signal is rectangular waves.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a DC brushless motor device controlled by an inverter.

[0002]

2. Description of the Related Art FIG. 10 is a diagram showing a configuration of a conventional DC brushless motor. In the figure, 1 is a DC power supply, 2 is an inverter for converting a DC current from the DC power supply 1 into an AC current, 3 is composed of a stator 3a having a winding coil and a rotor 3b having a permanent magnet. DC brushless motor operated by alternating current, 4 is a position detecting means for comparing a reference voltage from DC power supply 1 with a terminal voltage of DC brushless motor 3, 5 is control for controlling inverter 2 to drive inverter 2 Control means for outputting a signal.

A normal three-phase DC brushless motor rotates a rotor having a permanent magnet by passing independent alternating currents through three winding coils in a stator 3a. Are controlled by the control device. In the figure, the control device includes an inverter 2 for applying a voltage and a frequency to energize each of three phases of a DC brushless motor 3, that is, a U phase, a V phase, and a W phase, and a rotor based on a terminal voltage of the DC brushless motor 3. Position detecting means 4 for detecting the position 3b and outputting this position detection signal
And control means 5 for obtaining a voltage application firing timing for controlling the rotation of the DC brushless motor based on the position detection signal, and controlling the on / off of each switch element of the inverter 2 based on the voltage application firing timing. Have. The DC power supply 1 is switched by the inverter 2 to apply a voltage to the phase winding of the DC brushless motor 3 to switch the energization, while detecting the position of the rotor 3b based on the terminal voltage waveform and detecting the position of the rotor 2b based on the position detection signal.
To control the rotation of the DC brushless motor 3. Here, the position detecting means 4 compares each phase terminal voltage waveform with the reference voltage, and outputs the comparison result to the control means 5 as a position detection signal. / 2, that is, the DC bus voltage V
One half of dc is used. The position detection method is performed as follows. The terminal voltage of each phase is input to the position detecting means 4 as needed. In general, the magnitude relationship between the terminal voltage and the reference voltage is compared, and a location where the magnitude relationship is reversed, that is, a point where the polarity is reversed is called a zero cross point. The position of the rotor 3b is detected based on the zero cross. That is, the position detection timing is determined by the zero cross timing.
When the voltage applied to the DC brushless motor 3 is performed by pulse width modulation, the control unit 5 generates and realizes a switch element drive signal so that the ignition switch at each time is chopped in a predetermined manner.

[0004]

Generally, in order to drive a DC brushless motor efficiently and at a high rotation speed, it is necessary to energize the inverter applied voltage phase to a position advanced from the induced voltage phase of the DC brushless motor. However, the position detection signal can be detected only during the power-supply suspension period when power is not supplied to each phase, and the power-supply suspension period is required from the predetermined phase to this signal detection timing, that is, from the polarity change of the position detection signal. Therefore, the lead angle of the applied voltage phase of the inverter cannot be advanced beyond a predetermined value. When the conventional position detection circuit 4 is used, the position detection signal always senses the zero cross point of the terminal voltage, so that the firing phase of the applied voltage can advance only up to the zero cross point of the terminal voltage at the maximum. Therefore, even if it is desired to fire the applied voltage prior to the zero-cross point of the induced voltage in order to realize high-efficiency operation or high rotation,
There was a problem that we could not meet that demand. SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide an inverter device and a control method capable of increasing a lead angle of an applied voltage phase with respect to an induced voltage phase.

[0005]

A first aspect of the present invention is a DC brushless motor device having a plurality of phases, the rotation of which is controlled by an inverter, wherein each phase in the DC brushless motor is controlled based on a control signal. An inverter that conducts electricity,
Position detecting means for detecting the rotational position of the DC brushless motor based on a reference signal, and control means for outputting the control signal to the inverter based on a position detection result by the position detecting means, The reference signal is a square wave.

In a second aspect based on the first aspect, the position detecting means detects the rotational position of the DC brushless motor by comparing the reference signal with an induced voltage of each phase of the DC brushless motor. .

In a third aspect based on the first aspect, the position detecting means detects the rotational position of the DC brushless motor for each of the plurality of phases based on the same reference signal, and The means outputs a control signal for each of the plurality of phases of the DC brushless motor to the inverter based on a position detection result for each of the plurality of phases by the position detecting means.

According to a fourth aspect, in the first aspect, the reference signal and the control signal are synchronized with each other.

According to a fifth aspect, in the first aspect, the amplitude of the reference signal is changed according to the input current of the inverter.

In a sixth aspect based on the first aspect, the amplitude of the reference signal is changed according to the output frequency of the inverter or the output voltage of the inverter.

A seventh aspect of the present invention is a DC brushless motor device, wherein the motor has a plurality of phases and the rotation of which is controlled by an inverter, in a compressor for compressing gas by operating a cylinder by rotation of the motor. An inverter for energizing each phase in the DC brushless motor based on a control signal, position detecting means for detecting a rotational position of the DC brushless motor based on a reference signal, and a position detection result by the position detecting means. Control means for outputting the control signal to the inverter based on the
The reference signal is a DC brushless motor device having a square wave.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 In the present embodiment, portions denoted by the same reference numerals as those in the conventional example indicate the same or corresponding portions. FIG. 1 is a diagram showing a configuration of an inverter device according to this embodiment. In the figure, 1 is a DC power supply, 2 has a plurality of switch elements that operate based on a control signal, converts DC from the DC power supply 1 into AC, and based on the plurality of switch elements, a DC brushless motor 3 described later. , An inverter for supplying an AC current to the windings of the stator 3a, and a DC brushless device 3 comprising a stator 3a having a plurality of windings and a rotor 3b having permanent magnets, and operating with the AC current from the inverter 2. motor,
Reference numeral 4 denotes position detecting means for comparing a reference voltage as a reference signal output from the reference signal generating means 6 with a terminal voltage of the DC brushless motor 3, and reference numeral 5 denotes a control signal for controlling the inverter 2 to drive the inverter 2. Control means for outputting,
Reference numeral 6 denotes a reference signal generating means having a D / A converter 7;
Is a microcomputer comprising a control means 5, a reference voltage generating means 6 and a D / A converter 7, and 9 is a compressor comprising a DC brushless motor 3 and a cylinder 10.

Next, the operation will be described. This embodiment is different from the conventional example in the setting of the reference voltage and the setting of the rotor 3b.
Since the method of position detection is different, only this point will be described.

First, a DC current output from DC power supply 1 is input to inverter 2, and の of DC bus voltage Vdc from DC power supply 1 is input to reference voltage generating means 6. Next, each switch element in the inverter 2 is operated based on a control signal from the control means 5, and DC
When an alternating current is applied to a specific winding in the stator 3a of the brushless motor, a magnetic field is generated in the stator 3a, and the rotor 3b is rotated by the action of the magnetic field. The control signal is generated and output based on a clock in the control means 5.

Next, the position detecting means 4 acquires an induced voltage, that is, a so-called terminal voltage, which is generated in a winding to which the AC current is not supplied from the inverter 2 among a plurality of windings in the stator 3a. . The induced voltage is a voltage caused by an induced electromotive force generated when the rotor 3b rotates and a magnetic flux passes through the winding. Further, the terminal voltage is simply referred to as the stator 3a.
And includes a voltage due to induced electromotive force, a DC voltage supplied from a DC power supply, and the like. Further, the position detection means 4 calculates the position of the rotor 3b by comparing the terminal voltage with an existing reference voltage output from a reference voltage generation means 6 described later, and uses the calculation result as a position detection signal as a position detection signal. Output to The position detection is calculated in the same manner as in the conventional example, and is calculated from the magnitude relationship between the terminal voltage and the existing reference voltage.

Next, the control means 5 outputs a control signal to each switch element in the inverter 2 based on the position detection signal. At the same time, the reference voltage generating means 6
To output the energization mode information. The energization mode information indicates what AC current is output to which winding in the stator 3a from the inverter 2, and two types of positive and negative phases are provided for one winding. Obviously it exists. Generally, in the case of a three-phase DC brushless motor, there are six types as described later. The power-on mode information is generated and output based on a clock in the control means 5.

Next, in the reference generating means 6, a square wave AC voltage pattern is created based on the energizing mode information from the control means 5, and the DC bus voltage Vdc from the DC power supply 1 is generated.
And a new reference voltage is created by superimposing the half-wave on the AC voltage pattern of the square wave created earlier. This reference voltage is sent to the position detecting means 4 as an analog value via the D / A converter 7.

Next, using the new reference voltage sent to the position detecting means 4, the terminal detecting means 4 compares the terminal voltage with the new reference voltage as described above, and controls again as a position detecting signal. Output to means 5. Thereafter, the position detection result from the position detection means 4 is sequentially reflected on the reference voltage, and the position detection is repeated.

Next, comparison between the reference voltage and the terminal voltage by the position detecting means 4 will be described. FIG. 2 is a diagram showing a time chart for one phase of the U phase of the reference voltage generating means 6 and the position detecting means 4. In the drawing, C1 and C2 denote an energization suspension period during which no current is supplied from the inverter 2 to the U phase, and D denotes an other phase detection period during which current is supplied to the U phase and position detection is performed in phases other than the U phase. Also, the reference voltage A
Is a reference voltage in the conventional example fixed to 1/2 of the DC bus voltage Vdc, and is indicated by a two-dot broken line. On the other hand, the reference voltage B is an example of the reference voltage according to the present embodiment, and is indicated by a dashed line.

(A) UP drive signal Sup for outputting a positive-phase signal with respect to the U-phase, and (A) UN drive signal Sun for outputting a negative-phase signal with respect to the U-phase. ,
(C) is a U-phase terminal voltage, (D) is a position detection signal A detected and output at the reference voltage A, and (E) is a position detection signal B detected and output at the reference voltage B.

FIG. 2 shows that the lead angle of the applied voltage with respect to the induced voltage (hereinafter referred to as “lead angle”) is the amplitude ΔVt of the AC signal.
Obviously, it can be controlled by changing h. Generally, in order to control the advance angle, a method of controlling the angle α between the zero-cross timing of the position detection signal and the firing timing of the applied voltage is used. However, this method has a limitation that the ignition timing of the applied voltage cannot be advanced earlier than the zero-cross timing as described in the conventional example. That is, in the related art, the applied voltage cannot be fired earlier than the zero-cross timing of the induced voltage.

Next, the operation will be described. First, a method of position detection using a reference voltage in a conventional example will be described. The position detection by the position detecting means 4 is performed by the reference voltage B
The position detection signal is performed at a zero-cross point where the terminal voltage and the terminal voltage intersect, and the position detection signal becomes as shown by an upward or downward arrow in FIG.

Next, a method of position detection using a reference voltage in the present embodiment will be described. In this embodiment, the reference voltage A is generated by using the reference voltage generating means 6 and superimposing an AC voltage as a square wave having a delayed phase on the applied voltage of the reference voltage B. That is, instead of being always constant like the reference voltage B, the AC voltage is a square wave having a constant amount ΔVth amplitude like the reference voltage B as shown in the figure. The switching of the addition or subtraction of ΔVth is performed in the other phase detection period D during which the position detection is not performed.
Done in

Therefore, the position detection by the position detecting means 4 is performed at the zero cross point where the reference voltage A and the terminal voltage intersect, and the position detection signal is as shown by an upward or downward arrow in (e). That is, when the position is detected by the reference voltage A, the phase is output with a phase advanced from the zero-cross timing when the position is detected by the conventional reference voltage B. Therefore, since the control means 5 generates the firing timing of the applied voltage based on the advanced position detection signal, the phase of the applied voltage also advances.

Next, the energization mode information will be described.
FIG. 3 is a diagram showing the energization mode information and the state of each switch element in the three-phase DC brushless motor device. In the drawing, the phase represents the rotational position of the rotor 3b in an angle, the ignition switch indicates the ON state of the switch element in the inverter 2, and the symbol of the ignition switch is shown in FIG. Corresponds to things. The position detection phase is a phase for which the position is detected among the U phase, V phase, and W phase. This is a state where the voltage is decreasing. That is, in FIG. 2, the section C1 corresponds to the U ↑ position detection phase, and the section C2 corresponds to the U ↓ position detection phase.

Next, the operation will be described. First, when the phase of the rotor 3b is between 30 and 90, only the UP and VN of the switch elements in the inverter 2 are turned on. That is, a DC current is applied to the U-phase winding in the forward direction, and a DC current is applied to the V-phase winding in the reverse direction. The position detection is performed by the W-phase winding. It goes without saying that the induced voltage generated in the W phase is in a reduced state. The position of the rotor 3b is detected by this position detection, and when the phase of the rotor 3b becomes 90 degrees, the ignition switch VN switches to OFF and WN switches to ON. Thus, the rotor 3
The phase in which b is between 30 and 90 is referred to as a first energization mode.

Next, the phase of the rotor 3b is changed from 90 to 150.
During this period, only UP and WN of the switch elements in the inverter 2 are ON. That is, a DC current is applied to the U-phase winding in the forward direction (positive phase), and a DC current is applied to the W-phase winding in the reverse direction (reverse phase). The position detection is performed by the V-phase winding. It goes without saying that the induced voltage generated in the V phase is increasing.
The position of the rotor 3b is detected by this position detection, and when the phase of the rotor 3b becomes 150 degrees, the U of the ignition switch
P switches OFF and VP switches ON. Thus, the phase of the rotor 3b between 90 and 150 is called the second energization mode.

Hereinafter, the same applies to phases other than those described above.
Description is omitted. Note that the phase of the rotor 3b is changed from 150 to 2
The interval between 10 is the third energization mode, and the phase of the rotor 3b is 21
The period between 0 and 270 is referred to as a fourth energizing mode, the phase of the rotor 3b between 270 and 330 is referred to as a fifth energizing mode, and the phase of the rotor 3b between 330 and 30 is referred to as a sixth energizing mode.

As described above, in this embodiment, the DC voltage and the AC voltage as a square wave are superimposed to create a reference voltage,
The rotor 3b of the DC brushless motor is
, The position detection timing, that is, the zero-cross timing can be advanced as long as the amplitude of the induced voltage is within the range, and can be shared with the conventional advance control. The range can be expanded, and especially the rotation range on the high-speed side can be expanded.

Although the operation of the reference voltage has been described for one phase, it is clear that the generation of the reference voltage should be performed for three phases in order to obtain position detection signals for three phases. .

When the control means 5 is a digital control circuit such as a microcomputer in the present invention, a circuit for converting the reference voltage generation means 6 into an analog voltage is required. In this embodiment, the D / A converter 7 in the microcomputer 8 is used, but the circuit may be provided outside.

When a microcomputer 8 with a built-in A / D converter is used, the position detecting means 4 in addition to the reference voltage generating means 6 can be built in the microcomputer 8, so that the circuit size is further reduced. And recyclability can be improved.

Embodiment 2 FIG. In the present embodiment, portions denoted by the same reference numerals as those in Embodiment 1 indicate the same or corresponding portions. The structure of the present embodiment is the same as that of the first embodiment, and only the waveform of the reference voltage is different. FIG.
FIG. 3 is a time chart showing the operation of each unit when a three-phase reference voltage signal is shared, but differs from FIG. 2 in that a common reference voltage in which three-phase position detection is indicated by a thick line is used. In the figure, the bold line is a common reference voltage shared by all three phases, and corresponds to an analog value output from the D / A converter 7 in FIG. Also, (A),
(A) and (c) show the time changes of the U-phase, V-phase, and W-phase terminal voltages, respectively, and the phases of each phase are shifted by 2π / 3 each.

Next, the operation will be described. The position detection method is the same as the method described with reference to FIG. 2 except that the three-phase position detection uses a common reference voltage indicated by a bold line, and only this point will be described. As is clear from the figure, it is understood that the zero-cross point in each phase, that is, the position detection is detected without omission by using the common reference voltage indicated by the thick line. In this way, the zero cross timings of all three phases can be controlled by the same common reference voltage.

As described in the present embodiment, the same effect can be obtained even when the same common reference voltage is used. It is needless to say that the non-energized phase of the different phase is limited to the energized phase and does not occur simultaneously.

In this embodiment, three phases are described, but the invention is not limited to three phases. However, 1
In order to perform position detection using two common reference voltages, three or more phases and an odd phase are preferable. This is because two or more zero-cross points of the induced voltage at the same time occur at the same time if the phases are even-numbered phases, and the crossing polarities at the zero-cross points are opposite. That is, when position detection is performed using the same reference voltage on which the same ΔVth is superimposed, the phase of the zero-cross point advances on the one hand, and the phase of the zero-cross point delays on the other hand, meaning that control cannot be performed with one common voltage. Become. Of course, even in this case, it is possible to control the phase of the phase of the zero-cross point to be advanced and the phase of the phase to be delayed by using the common reference voltage as in the present embodiment.

When the common reference voltage is created, the common reference voltage is created such that the polarity switching timing of the common reference voltage and the energized phase switching timing are synchronized. Here, the energized phase switching timing is equivalent to the energized mode information described in the first embodiment, and is a timing at which the inverter 2 switches a phase to which energization is performed. The switching timing is controlled by a control signal, and the energized phase switching timing is equivalent to the timing of the control signal. The switching timing of the ignition switch in FIG. 3, that is, the phase is 30, 90,
150, 210, 270, 330. Furthermore, the reference voltage is equivalent to the reference voltage created based on the energization mode information. Needless to say, this energized phase switching timing is generated and output by the clock in the control means 5.

On the other hand, the polarity switching timing of the common reference voltage is a timing at which the polarity is inverted with respect to Vdc / 2, and is equivalent to the reference voltage described in the first embodiment. Since the reference voltage is generated and output by the clock in the control means 5, it is needless to say that the polarity switching timing of the common reference voltage is similarly generated and output by the clock in the control means 5.

Therefore, since both the polarity switching timing of the common reference voltage and the energized phase switching timing are based on the clock in the control signal 5, it is very easy to synchronize both timings. Further, if the polarity switching timing of the common reference voltage and the energized phase switching timing are synchronized,
When the energized phase is switched, the position detection phase based on the induced voltage is switched. That is, in FIG.
The position detection timing is detected at the position b in the section 1 (U $), the ignition switch is switched, the mode is switched from the sixth conduction mode to the first conduction mode, and at the same time, W is detected in the position detection phase in the section E2. ↓ means that the position detection starts.

Next, a case where the polarity switching timing of the common reference voltage and the energized phase switching timing are not synchronized will be described. FIG. 5A shows a case where the polarity switching timing of the common reference voltage and the energized phase switching timing are not synchronized. The section indicated by T in the figure is a section that cannot be used for position detection because the polarity of the common reference voltage has not been switched. As described in the first embodiment, DC
In order to rotate the brushless motor at high speed, it is necessary to increase the amplitude of the common reference voltage to advance the phase of the zero cross point between the common reference voltage and the induced voltage. That is, if the section indicated by T can be used for the zero-cross point, it is possible to perform higher-speed rotation. Therefore, the switching of the common reference signal is preferably performed simultaneously with the switching of the energized phase.

Next, the waveform of the common reference voltage will be described. FIG. 5B shows a case where a common reference voltage is used as a triangular wave instead of a square wave. When the common reference voltage shown by the solid line in the figure is used and the phase between the common reference voltage and the terminal voltage shifts for some reason and becomes a common reference voltage indicated by a broken line, or when a triangular wave is used, the zero crossing point is used. Will also be out of phase. As described above, even a slight phase fluctuation affects the zero-cross point, and stable rotation cannot be obtained.

FIG. 5C shows the case where a common reference voltage is used as a square wave, particularly a square wave having a trapezoidal waveform.
When the common reference voltage indicated by the solid line in the drawing has a phase delayed for some reason and becomes the common reference voltage indicated by the broken line, unlike the case where the common reference voltage as a triangular wave described with reference to FIG. It can be seen that even when the phase of the common reference voltage is shifted, the detection of the zero cross point is not affected. This is because a section constant for a common reference voltage value characteristic of a square wave is used as a zero cross point. Therefore, it is desired that the common reference voltage is a square wave.

The section indicated by T in the figure is a stage in which the polarity of the common reference voltage is being switched. As described with reference to FIG. 5B, when the section indicated by T is used as the zero-cross point, the DC brushless motor can rotate at higher speed. Therefore, it is desired that the waveform of the common reference voltage is a rectangular wave as shown in FIG. 4 among the square waves.

As can be seen from these examples, the polarity switching timing of the common reference voltage is synchronized with the energized phase switching timing, and the waveform is a square wave, especially a rectangular wave, so that a higher speed and stable rotation can be obtained. . Of course, it is needless to say that the operation can be performed even when the polarity switching timing of the common reference voltage and the energized phase switching timing are not synchronized. Further, in this embodiment, the AC component of the voltage output from the reference voltage generating means 6 is shown as a square wave, but is not limited to this, and may be, for example, a sine wave. However, a square wave can be realized simply by chopping a DC voltage, and is easy to generate.

As described above, in this embodiment, since the common reference voltage is used for detecting the positions of a plurality of phases, the circuit configuration is simplified and the cost is reduced. In addition, since position detection is performed by comparing the induced voltage from each phase with the reference voltage by the position detection means, synchronization can be performed using the same clock, which simplifies the circuit and reduces cost.

Embodiment 3 In the present embodiment, portions denoted by the same reference numerals as those in Embodiment 1 indicate the same or corresponding portions. Note that the present embodiment differs from the first embodiment in the method of setting the reference voltage, and therefore only this point will be described. FIG. 6 is a diagram showing a configuration of the inverter device according to this embodiment. In the figure, 11 is energization switching timing information, and 12 is an input current value. Further, the reference voltage generating means 6 is configured to output the input current value 1
2, energized phase switching timing information 11 and DC bus voltage V
A reference voltage signal is output based on 1/2 of dc.

In general, the relationship between the lead angle and the voltage, current, frequency and torque in a cylindrical (non-salient) DC brushless motor will be described. These relationships can be expressed by the following equations (1), (2), (3), and (4).

[0048]

(Equation 1)

In the equations (1) to (4), Vd is d
Axis voltage, Vq is q-axis voltage, R is motor resistance, ω is frequency, L is winding inductance, Id is d-axis current, Iq is q-axis current, Φ is magnetic flux, V is output voltage of inverter, and β is lead. The angle, τ is the output torque, and kt is the torque constant. Here, the center of the magnetic flux of the magnet is the d-axis, and the electrical angle π /
The two phases are called the q axis.

It is clear from the above equation that the lead angle β can be a means for operating the current and voltage of the motor. Generally, the output voltage V of the inverter is used as an operation amount for controlling the speed of the motor, and Iq is uniquely determined by the load torque. Therefore, the lead angle β can be used as an operation amount for controlling Id. Specifically, the larger the advance angle β, the smaller the Id. Also, since the operating point where Id = 0 is the maximum efficiency point of the motor,
If the lead angle β is controlled according to the input current of the inverter 2, high-efficiency operation can be realized.

According to equations (1) to (4), the maximum efficiency (Id =
0) If the lead angles are β1 and β2, if τ1> τ2, β
Since 1> β2, the motor can be efficiently controlled by controlling the lead angle in accordance with the output torque. From equations (1) to (4), if the lead angle β is increased, I
It is also apparent that d decreases and the output voltage V of the inverter decreases. In other words, if the lead angle β is increased, it is possible to operate up to higher rotation even if the DC bus voltage is constant. For example, ΔVth according to the output frequency of the inverter
Is increased, the rotation range on the high-speed side can be expanded efficiently on the low-speed side.

Next, the operation will be described. First, the reference voltage generator 6 detects an input current to the inverter 2 and obtains an input current value. Further, a voltage value ΔVth corresponding to the amplitude of the reference voltage having a positive correlation with the input current value is calculated. Next, the reference voltage generating means 6 acquires the energized phase switching timing from the control means 5, and obtains the voltage value Δ
An AC component is created from Vth and the energized phase switching timing. Next, 1 / (1) of the DC bus voltage Vdc from the DC power supply 1
2 is acquired, and the AC component created earlier is superimposed as a reference voltage. Thereafter, position detection and D
Controls the C brushless motor.

From the above-mentioned equations (1) to (4), if the operating frequency is constant, the current value input to the inverter 2 depends on the load torque. As described above, highly efficient operation according to the load torque can be performed. In this embodiment, an example in which only the inverter input current is considered for ΔVth has been described.
If the operating frequency of the C brushless motor can also be taken into consideration, it is possible to control more efficiently even if the operating frequency of the DC brushless motor is changed.

As described above, in this embodiment, ΔVth increases and decreases in accordance with the current value input to the inverter 2 to increase and decrease the advance angle β, so that highly efficient operation is possible.

Embodiment 4 In the present embodiment, portions denoted by the same reference numerals as those in Embodiment 3 indicate the same or corresponding portions. FIG. 7 is a diagram showing a configuration of the inverter device according to this embodiment. In the figure, reference numeral 13 denotes output frequency information of the inverter. The reference voltage generating means 6 outputs a reference voltage signal based on the output frequency information of the inverter indicating the output frequency of the control means 5, the energized phase switching timing information indicating the energized phase switching timing, and 1/2 of the DC bus voltage Vdc. Things.

Next, the operation will be described. First, the reference voltage generator 6 obtains the output frequency information 13 and the energization switching timing information of the inverter 2 of the inverter 2 from the controller 5. Further, the output frequency information 13 of this inverter
Voltage value ΔV corresponding to the amplitude of the reference voltage having a positive correlation with
Th is calculated, and an AC component is created by adding or subtracting ΔVth in accordance with the energization switching timing. At this time, ΔVth is created so that the advance angle β increases with an increase in the output frequency of the inverter. next,
Acquire 1/2 of the DC bus voltage Vdc from the DC power supply 1,
The AC component created earlier is superimposed on a reference voltage.
Thereafter, the same position detection and control of the DC brushless motor as in the first embodiment are performed.

As described above, in this embodiment, the lead angle β increases with the increase of the output frequency of the inverter. Therefore, from the equations (1) to (4), the output voltage of the inverter during high-speed operation is small. In other words, it is possible to operate up to high rotation. Because the DC voltage from the DC power supply 1 is chopped by the switch element in the inverter 2 to generate the output voltage of the inverter, the output voltage of the inverter 2 does not exceed the voltage value of the DC power supply. Therefore, the voltage required to rotate at the same operating frequency can be reduced, in other words, the number of rotations that can be operated at the maximum voltage can be increased.

Embodiment 5 FIG. In the present embodiment, portions denoted by the same reference numerals as those in Embodiment 4 indicate the same or corresponding portions. This embodiment is different from the fourth embodiment in that the output voltage information of the inverter is used instead of the output frequency of the inverter, and this point will be described.
FIG. 8 is a diagram showing a configuration of the inverter device according to this embodiment. In the figure, reference numeral 14 denotes output voltage information of the inverter.

Next, the operation will be described. Generally, when a motor is driven at a variable speed, it is known that the output frequency of the inverter is substantially proportional to the output voltage of the inverter. Therefore, in the operation described in the fourth embodiment, the output voltage information 14 of the inverter may be used instead of the output frequency 13 of the inverter.

As described above, in this embodiment, since the lead angle β is changed with respect to the output voltage information of the inverter,
From the expressions (1) to (4), the output voltage of the inverter during high-speed operation can be reduced, that is, the operation can be performed up to high rotation.

Embodiment 6 FIG. FIG. 9 is a configuration diagram of an air conditioner using the compressor 9 to which the DC brushless motor device described in the first to fifth embodiments is applied.

In general, a hermetic compressor has the characteristic that the refrigerant used has a larger dielectric constant than air and a large leakage current due to a small ground-to-ground impedance. It increases as the voltage increases. On the other hand, as means for speeding up the compressor,
As described above, there are a method of advancing the phase of the zero cross timing and a method of increasing the DC voltage of the inverter. If the speed is increased by the latter method, an electric leakage may occur during operation and the earth leakage breaker may fall. Further, in order to increase the DC voltage, it is necessary to add a booster circuit to the power supply circuit, which causes an increase in cost.

Therefore, if a DC brushless motor that can be operated up to a high rotation range by advancing the phase of the zero-cross timing is applied to the compressor, the capacity can be increased without changing the configuration of the compressor 9. In addition, when the compressor 9 is mounted on an air conditioner, it is possible to improve the heating capacity at which the compressor needs to be driven at a high speed.

[0064]

According to a first aspect of the present invention, there is provided a DC brushless motor device having a plurality of phases, the rotation of which is controlled by an inverter, wherein an inverter energizes each phase in the DC brushless motor based on a control signal. And position detecting means for detecting a rotational position of the DC brushless motor based on a reference signal; and control means for outputting the control signal to the inverter based on a position detection result by the position detecting means. Since the reference signal is a square wave,
The variable range of the lead angle can be expanded.

According to a second aspect of the present invention, in the first aspect, the position detecting means compares the reference signal with the induced voltage of each phase of the DC brushless motor to detect the rotational position of the DC brushless motor. The rotation range on the high-speed side can be expanded.

In a third aspect based on the first aspect, the position detecting means detects the rotational position of the DC brushless motor for each of the plurality of phases based on the same reference signal, and The circuit outputs a control signal for each of the plurality of phases of the DC brushless motor to the inverter based on a position detection result for each of the plurality of phases by the position detection means, so that a circuit configuration is simplified. .

According to a fourth aspect, in the first aspect, since the reference signal and the control signal are synchronized with each other, they can be synchronized using the same clock.

According to a fifth aspect, in the first aspect, the amplitude of the reference signal is changed in accordance with the input current of the inverter, so that a high-efficiency operation can be realized.

According to a sixth aspect, in the first aspect, the amplitude of the reference signal is changed in accordance with the output frequency of the inverter or the output voltage of the inverter, so that high-efficiency operation can be realized.

A seventh aspect of the present invention is a DC brushless motor device, wherein the motor has a plurality of phases and the rotation of which is controlled by an inverter, in a compressor for compressing gas by operating a cylinder by rotation of the motor. An inverter for energizing each phase in the DC brushless motor based on a control signal, position detecting means for detecting a rotational position of the DC brushless motor based on a reference signal, and a position detection result by the position detecting means. Control means for outputting the control signal to the inverter based on the
Since the reference signal is a DC brushless motor device having a square wave, the capacity can be increased without changing the configuration.

[0071]

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 2 is a time chart of reference voltage generating means and position detecting means for one phase.

FIG. 3 is a diagram showing a conduction mode and a state of each switching element.

FIG. 4 is a time chart showing the operation of each unit when a three-phase reference voltage signal is shared.

FIG. 5: Position detection with different common reference voltages.

FIG. 6 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 7 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 8 is an overall configuration diagram showing an embodiment of the present invention.

FIG. 9 is a configuration diagram of an air conditioner.

FIG. 10 is a configuration diagram showing a conventional device.

[Explanation of symbols]

1 DC power supply, 2 inverters, 3 DC brushless motor, 3a DC brushless motor stator, 3b D
C brushless motor rotor, 4 position detecting means, 5
Control means, 6 reference voltage generating means, 7 D / A converter, 8 microcomputer, 9 compressor, 10 cylinder, 11 energization switching timing information, 12 input current value, 13 inverter output frequency information, 14 inverter output voltage information .

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Isao Kawasaki, 2-3-2 Marunouchi, Chiyoda-ku, Tokyo F-term within Mitsubishi Electric Corporation (reference) 5H560 AA02 BB04 BB12 DA13 DA19 DC01 DC12 EB01 GG04 SS01 SS07 UA06 XA12 XA13 XA15 XB09

Claims (7)

[Claims] 1. A DC brushless motor device having a plurality of phases, the rotation of which is controlled by an inverter, wherein the inverter energizes each phase in the DC brushless motor based on a control signal and a reference signal. Position detecting means for detecting the rotational position of the DC brushless motor, and control means for outputting the control signal to the inverter based on a position detection result by the position detecting means, wherein the reference signal is DC characterized by being a square wave
Brushless motor device. 2. The method according to claim 1, wherein said position detecting means is configured to detect said reference signal and said D signal.
C. Compare the induced voltage of each phase of the brushless motor
2. The DC brushless motor device according to claim 1, wherein a rotation position of the C brushless motor is detected. 3. The position detecting means detects the rotational position of the DC brushless motor for each of the plurality of phases based on the same reference signal. 2. The DC brushless motor device according to claim 1, wherein a control signal for each of the plurality of phases of the DC brushless motor is output to the inverter based on a position detection result for the plurality of phases. 3. 4. The DC brushless motor device according to claim 1, wherein said reference signal and said control signal are synchronized with each other. 5. The DC brushless motor device according to claim 1, wherein the amplitude of the reference signal is changed according to the input current of the inverter. 6. The DC brushless motor device according to claim 1, wherein the amplitude of the reference signal is changed according to an output frequency of the inverter or an output voltage of the inverter. 7. A compressor in which a cylinder is operated by rotation of a motor to compress a gas, wherein the motor has a plurality of phases, and is a DC brushless motor device whose rotation is controlled by an inverter. DC based
An inverter for energizing each phase in the brushless motor, position detecting means for detecting a rotational position of the DC brushless motor based on a reference signal, and an inverter based on a position detection result by the position detecting means. And a control means for outputting the control signal, wherein the reference signal is a DC brushless motor device having a square wave.