JP2003189671A - Motor drive - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor drive with a simple construction that can reduce operating noise and vibration. <P>SOLUTION: The motor drive has a DC-AC converting means 4 that outputs a pseudo AC voltage to a three-phase brushless DC motor 5, a magnetic pole detecting means 1 that detects the induced voltage of the armature winding, and a pulse width modulation (PWM) duty ratio control means 3 that controls the switching element of the DC-AC conversion means 4. It is provided with a leakage flux estimating means 6 that calculates the amount of leakage flux within the motor based on a prescribed electrical physical quantity, and a current angle setting means 2 that controls the current angle of the armature current to maintain the calculated leakage flux amount to a prescribed value or lower, so that operating noise and vibration may be reduced with a simple construction. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor drive device for frequency controlling a brushless DC motor.

[0002]

2. Description of the Related Art A three-phase brushless DC motor is extremely easy to maintain and has an explosion-proof structure because there are no brushes and slipping. Therefore, the three-phase brushless DC motor is widely used in various fields. And such a three-phase brushless DC
A motor driving device that drives or controls the motor is attached to the motor.

FIG. 9 shows a schematic structure of a 120 ° energization control type (rectangular wave energization control type) motor drive device for controlling the rotation speed of a three-phase brushless DC motor. As shown in FIG. 9, this motor drive device is provided with magnetic pole position detection means 101.
And a PWM duty control means 103 and a DC / AC conversion means 104. Here, the magnetic pole position detection means 10
1 detects the position of the rotor of the brushless DC motor 105 (hereinafter, abbreviated as "motor 105"). P
The WM duty control means 103 outputs a duty signal for controlling the applied voltage, frequency and phase for controlling the rotation speed of the motor 105. DC / AC conversion means 104
Converts the DC voltage into a pseudo AC voltage and outputs it to the motor 105. The DC / AC converter 104 includes six switching elements that open and close at high speed.

In the motor drive device thus constructed, the DC voltage is converted by the DC / AC converting means 104.
The frequency and the phase are converted into a pseudo AC voltage having a variable value and output to the motor 105. Here, the rotation speed of the motor 105 is controlled by changing the frequency and phase (hereinafter, referred to as “inverter frequency”) of the pseudo AC voltage output from the DC / AC converter 104. This inverter frequency is controlled by the PWM duty control means 103. The PWM duty control means 103 opens / closes the switching element of the DC / AC conversion means 104.
Output the street base pattern. The switching elements are opened and closed by these base patterns, and thereby the inverter frequency output from the DC / AC converting means 104 is controlled. Here, the reciprocal of one cycle of the base pattern is the inverter frequency.

When changing the number of rotations of the motor 105,
The PWM duty control means 103 controls the rotation speed of the motor 105 while changing the inverter frequency of the DC / AC conversion means 104 based on the rotation phase information input from the magnetic pole position detection means 101. Here, the phase detection characteristic of the magnetic pole position detection means 101 does not depend on the inverter frequency (phase) or the voltage amplitude output from the DC / AC conversion means 104, and directly detects the induced voltage generated from the motor 105 to obtain the motor 105. The magnetic pole position of is estimated and calculated.

The PWM duty control means 103 outputs six types of base patterns based on the rotation phase information. The DC / AC converting means 104 has six switching elements, each of which has one switching element in the upper arm and one in the lower arm for each of the U-phase, V-phase and W-phase. It is equipped with a switching element.

In the motor drive by such a conventional motor drive device, under the condition that the load torque applied to the motor 105 is small, the motor 105 exerts its original torque performance and good speed control performance is obtained. Further, the speed followability is good even for a considerable speed pulsation, and a sufficient high speed response can be secured. Further, since the configuration of the control circuit and the motor operation program are simple, there is an advantage that the cost of the entire system including the control circuit can be reduced.

[0008]

However, under the condition that the load torque applied to the motor 105 is large, the influence of the leakage magnetic flux between the stator and the rotor inside the motor is increased due to the increase of the armature current of the motor 105. It cannot be ignored. In particular, as the volume of the motor 105 becomes smaller, the ratio of the leakage magnetic flux increases remarkably. When such a phenomenon occurs, the motor 105 cannot exhibit the original torque performance.

In this case, (increase load torque)-(increase armature current)-(increase leakage magnetic flux amount)-(decrease motor generated torque)-(increase armature current)-(increase leakage magnetic flux amount),
Such a magnetic saturation phenomenon occurs, and the armature current continues to increase. For this reason, the driving efficiency may be deteriorated, heat may be generated, or power components may be burned, and in the worst case, the motor may be out of step and even damage the motor equipment. here,
If the volume of the motor 105 is increased, the high load torque region can be effectively used, and such a situation can be avoided. However, this causes problems that the cost of the motor increases and it is difficult to reduce the cost of the control device.

The present invention has been made to solve the above-mentioned conventional problems, and is directed to a motor (three-phase brushless DC).
Without increasing the volume of the motor, etc., the amount of magnetic flux leakage can be reduced under the condition that the load torque applied to the motor is high and the magnetic saturation phenomenon is likely to occur, and the original torque withstanding performance of the motor can be exhibited. It is an object to be solved to provide a low-cost motor drive device that can be performed.

Further, it is possible to suppress the occurrence of torque down in the motor to reduce noise or vibration generated in the mechanical system of the motor, and to simplify the noise prevention mechanism or vibration prevention mechanism. Providing a driving device is also a problem to be solved. Further, it is also intended to provide a motor drive device capable of ensuring very good speed control performance, speed followability or control stability under a situation where the load torque is small, without increasing the circuit cost. It should be an issue.

[0012]

A motor drive device according to a first aspect of the present invention made to solve the above problems includes (i) a switching element, and the switching element is opened and closed according to a control signal. A DC-AC converting means for converting the DC voltage into a desired pseudo-AC voltage and outputting the pseudo-AC voltage to a three-phase brushless DC motor;
i) A magnetic pole position detecting means for detecting a rotation phase obtained from an induced voltage of a three-phase armature winding of a three-phase brushless DC motor and outputting rotation phase information, and (iii) a switching element of a DC / AC converting means. In a motor drive device having PWM duty control means for outputting a control signal for PWM control of opening / closing operation, (iv) a three-phase brushless DC motor connected between the magnetic pole position detection means and the PWM duty control means. A leakage magnetic flux amount estimating means for calculating the leakage magnetic flux amount due to the action of the armature current between the stator and the rotor on the basis of a predetermined electrical physical quantity,
(V) Current conduction angle setting means for controlling the current conduction angle of the armature current so that the leakage magnetic flux amount calculated by the leakage magnetic flux amount estimating means is equal to or less than a predetermined value. .

A motor drive device according to a second invention of the present application is characterized in that the predetermined electrical physical quantity is an armature current. A motor drive device according to a third invention of the present application is characterized in that the predetermined electrical physical quantities are a DC voltage and a PWM duty.

In the motor drive device according to the fourth aspect of the present invention, the current conduction angle setting means increases the current conduction angle when the calculated leakage magnetic flux amount is larger than a predetermined value, and the leakage magnetic flux amount is a predetermined value. When it is further reduced, the current conduction angle is reduced. A motor drive device according to a fifth aspect of the present invention has a current conduction angle of 120 degrees or more.
It is characterized in that it has a current conduction angle setting means for setting it to less than 80 degrees.

A motor drive device according to a sixth aspect of the present invention is applied (applied) to a torque control device of a one-piston rotary compressor, and corresponds to a rotational load torque fluctuation of the one-piston rotary compressor, and is a three-phase brushless DC. It is characterized by having a PWM duty control means for controlling the electromagnetic torque generated by the motor. The motor drive device according to the seventh invention of the present application is applied (applied) to a torque control device of a one-piston rotary compressor, and a current conduction angle is increased in an operation region where torque control is required, and an operation without torque control is performed. The region is characterized by having current conduction angle setting means for reducing the current conduction angle.

In the motor drive device according to the eighth aspect of the present invention, the current conduction angle corresponding to only the maximum current in one cycle of the armature current is provided with respect to the periodic fluctuation of the armature current (effective value). It is characterized in that it has a current conduction angle setting means for fixing the leakage magnetic flux amount inside the three-phase brushless DC motor to a predetermined value or less. A motor drive device according to a ninth invention of the present application is characterized by having a current conduction angle setting means for changing the current conduction angle in a continuous discrete or stepwise manner.

[0017]

DETAILED DESCRIPTION OF THE INVENTION Referring to the accompanying drawings,
An embodiment of a motor drive device according to the present invention will be described in detail. (Structure of Motor Driving Device) First, the structure of the motor driving device will be described. FIG. 1A is a block diagram showing a schematic configuration of a motor drive device according to an embodiment of the present invention.
This motor drive is a three-phase brushless DC motor 5
(Hereinafter, abbreviated as “motor 5”)
The rotation speed is controlled by 0 ° to 180 ° energization control (rectangular wave energization control).

As shown in FIG. 1A, the motor driving device for controlling the motor 5 includes a magnetic pole position detecting means 1, a current conduction angle setting means 2, a PWM duty controlling means 3, and a DC / AC converting means 4. And a leakage magnetic flux amount estimating means 6. Here, the magnetic pole position detection means 1 detects the position of the rotor of the motor 5, and calculates the rotation speed from the detected rotor position of the motor 5. PWM duty control means 3
Outputs a PWM duty signal for controlling the applied voltage, frequency and phase for controlling the rotation speed of the motor 5.
The DC / AC converter 4 converts the DC voltage into a pseudo AC voltage and outputs it to the motor 5. The leakage magnetic flux amount estimating means 6 calculates the leakage magnetic flux amount.

The current conduction angle setting means 2 sets the current conduction angle such that the amount of leakage magnetic flux due to the action of the armature current between the stator and the rotor inside the motor 5 is set to a predetermined value or less. Specifically, the current conduction angle setting means 2 is connected between the magnetic pole position detecting means 1 and the PWM duty controlling means 3, and the rotation speed information and the rotor position information output from the magnetic pole position detecting means 1 are included, The current conduction angle is calculated based on the leakage magnetic flux amount calculation value inside the motor output from the leakage magnetic flux amount estimating means 6, and this is output to the PWM duty controlling means 3.

The current energization angle update data calculated by the current energization angle setting means 2 is output to the leakage magnetic flux amount estimation means 6. Further, the DC / AC converting means 4 has six switching elements, and for the U phase, V phase, and W phase,
Each of the upper arms has one switching element, and the lower arm has one switching element.

In the motor drive device thus constructed, the DC voltage supplied from the DC power supply is converted by the DC / AC converting means 4 into a pseudo AC voltage having a variable frequency and phase and output to the motor 5. The rotation speed of the motor 5 is the frequency and phase of the pseudo AC voltage output from the DC / AC converter 4 (hereinafter referred to as "inverter frequency").
It is controlled by changing. This inverter frequency is controlled by the PWM duty control means 3. The PWM duty control means 3 outputs a base pattern signal for opening / closing the switching element of the DC / AC converting means 4 based on this value. The switching elements are opened and closed by these base pattern signals, and thereby the inverter frequency output from the DC / AC converting means 4 is controlled.

The commutation switching of each base pattern signal is performed based on the output signal of the magnetic pole position detecting means 1. The magnetic pole position detection means 1 detects a zero-cross signal of the three-phase induced voltage of the motor 5, calculates rotor position information and rotation speed information from the detection signal, and outputs it to the current conduction angle setting means 2. The zero-cross signal (= rotor position information) is generated 6 times for 3 phases in one electrical angle cycle. In addition, zero cross occurs (3 × pole number) times during one rotation of the motor 5.
When the rotor position information of the magnetic pole position detection means 1 is input to the PWM duty control means 3 via the current conduction angle setting means 2, the PWM duty control means 3 outputs a base pattern signal based on the rotor position information. Switch sequentially.

(Base Pattern) Next, the base pattern output from the PWM duty control means 3 will be described. Here, the base pattern means a pulse signal for driving the switching element of the DC / AC converter 4. In the case of 120 ° energization, the base pattern has six basic patterns in one cycle of the electrical angle of the output voltage of the DC / AC converter 4. Here, the reciprocal of one cycle of the base pattern is the inverter frequency.

The first base pattern PTN1 electrically connects the U-phase upper arm switching element and the V-phase lower arm switching element. The second base pattern PTN2 is
The U-phase upper arm switching element and the W-phase lower arm switching element are electrically connected. Third base pattern PTN
3 conducts the V-phase upper arm switching element and the W-phase lower arm switching element. The fourth base pattern PTN4 electrically connects the V-phase upper arm switching element and the U-phase lower arm switching element. The fifth base pattern PTN5 includes a W-phase upper arm switching element and a U-phase upper arm switching element.
Conducts electrical connection with the lower arm switching element. The sixth base pattern PTN6 electrically connects the W-phase upper arm switching element and the V-phase lower arm switching element. P
The WM duty control means 3 sets the base pattern to PTN 1 → based on the rotation phase information of the magnetic pole position detection means 1.
PTN2 → ... → PTN6 → PTN1 are sequentially switched.

When the current conduction angle is set to 120 ° or more and less than 180 °, in addition to the six base patterns PTNn (n = 1 to 6) described for 120 ° conduction, a three-phase sinusoidal drive base pattern PTNsn ( There are 6 types of n = 1 to 6). Basically, in the section where the current is turned off in any one of the three phases (generated every 60 times), 1
A base pattern PTNn for controlling 20 ° energization is used. In other sections, the base pattern PTNSn is used. The base pattern PTNsn is a technique known as normal three-phase sine wave PWM control, and thus detailed description thereof is omitted here. The current conduction angle is 18
At 0 °, as the base pattern, only the three-phase sinusoidal wave driving base pattern PTNsn is used for driving.

FIG. 8 is an explanatory diagram of the current conduction angle. Figure 8
Then, the current conduction angle 36 is defined by Wx. Wx
= 120, 120 ° energization is achieved. In FIG. 8, if Wx <180 is satisfied, the induced voltage of the motor 5 can be confirmed, so that the motor 5 can be operated without providing a position sensor.
Further, when 120 <Wx <180, the addition of the three-phase sine wave driving base PTNsn in addition to the six types of base patterns PTNn described in the 120 ° energization control is as described above.

In FIG. 8, the armature current OFF start angle (= −X) to the armature current OFF end angle (= X) is a section in which the induced voltage of the motor 5 can be confirmed. Considering three phases, the section in which such an induced voltage can be confirmed exists once for each area of 60 electrical degrees. Therefore, considering one cycle of the inverter frequency (electrical angle of 360 °), there are six regions where the induced voltage can be confirmed.

(Operation of Leakage Magnetic Flux Amount Estimation Means) Next, the operation of the leakage magnetic flux amount estimation means 6 will be described. Here, the leakage magnetic flux means an armature current (hereinafter, “effective value” unless otherwise noted) between the stator and the rotor inside the motor 5.
Shall mean. ) Means that the magnetic flux does not pass through the inside of the rotor but passes through the surface of the rotor. Such a phenomenon is also called a magnetic saturation phenomenon. The leakage magnetic flux is also called an ineffective magnetic flux. When this phenomenon occurs, the motor generated torque is not proportional to the armature current, and the generated torque per unit current is significantly reduced, which causes deterioration of motor driving efficiency, current increase, noise increase or vibration increase. In particular, this phenomenon becomes more remarkable as the armature current increases during high load torque operation. Further, as the volume of the motor 5 becomes smaller, the leakage flux per unit current tends to increase, and it is necessary to reduce the leakage flux as much as possible.

In order to reduce the leakage magnetic flux, in terms of control,
It suffices to increase the current conduction angle of the armature current flowing through the motor 5. However, if the current conduction angle is simply increased, the section in which the induced voltage of the motor 5 is detected becomes short, and the robustness, speed responsiveness, and control stability of the motor 5 are impaired. Therefore, in the present invention, the leakage flux amount estimating means 6 calculates the leakage flux amount inside the motor 5, and the current conduction angle setting means 2 is set so that the leakage flux amount becomes a predetermined value or less.
The current conduction angle is set by. With such a configuration, it is possible to construct a motor drive device in which the control performance based on the high-speed response of 120 ° energization and the load torque withstanding performance due to the increased current energization angle are balanced in a high dimension.

FIG. 3 and FIG. 4 respectively show an armature current distortion rate-current conduction angle characteristic diagram showing the relationship between the armature current distortion rate and the current conduction angle, and a high load torque region (armature current). Is a leakage magnetic flux amount-current conduction angle characteristic diagram showing the relationship between the leakage magnetic flux amount and the current conduction angle at = I1max.

As can be seen from the leakage magnetic flux amount 18 in FIG. 4, the leakage magnetic flux amount 18 decreases when the current conduction angle is increased, and the leakage magnetic flux amount is almost 0 when the current conduction angle is 155 ° or more. Therefore, an effective current conduction angle capable of reducing the amount of leakage magnetic flux is sufficient if 120 ° ≦ current conduction angle ≦ about 165 ° when the conduction angle margin is + 10 °. If the current conduction angle in this range,
Since there is a detection section (at least 15 °) in which the induced voltage of the motor 5 can be sufficiently detected, a relatively stable control system can be constructed.

If the limit value of the leakage magnetic flux amount is set to the leakage magnetic flux amount limit value 14, the set value of the current conduction angle becomes 140 ° ≦ current in consideration of the characteristic intersection point 19 during high load torque operation. It suffices if the conduction angle is ≦ 165 °.

Further, according to the armature current distortion rate 15 in FIG. 3, the armature current distortion rate decreases as the current conduction angle increases, and becomes almost 0 when the current conduction angle is 180 °. Basically, there is an interphase relationship between the armature current distortion rate 15 and the leakage magnetic flux amount 18, and at the current conduction angle 140 ° at the characteristic intersection 16, the armature current distortion rate limit value 17 can be set. it can. This means that it is the same point as the leakage magnetic flux amount limit value 14. Therefore, it can be said that the amount of leakage magnetic flux increases with the armature current distortion rate, and it is considered that the distortion component in the armature current, that is, the multiple harmonic components, adversely affects the load torque performance of the motor 5.

(First Explanation of Leakage Magnetic Flux Calculation Method)
As a first method of calculating the amount of leakage magnetic flux, a method of calculating from the armature current will be described. In FIG. 1B, the amount of leakage magnetic flux of the motor 5 is calculated from the armature current 7.
The armature current 7 of the motor 5 is taken into the leakage magnetic flux amount estimating means 6, the leakage magnetic flux amount estimating means 6 calculates the leakage magnetic flux amount, and the calculated value is output to the current conduction angle setting means 2.

As shown in FIGS. 2A and 2B, the set value of the current conduction angle of the current conduction angle setting means 2 is set to the current conduction angle 10
When a constant value (near current conduction angle Iang1≉120 °) is set as described above, the leakage magnetic flux amount 12 has a relationship between the leakage magnetic flux amount and the armature current at that time. With the leakage magnetic flux amount 12, when the armature current = I1max, the leakage magnetic flux amount = Δφma
It becomes x1 and exceeds the leakage magnetic flux amount limit value 14. On the other hand, if the current conduction angle of the current conduction angle setting means 2 is set to the current conduction angle 11 and the current conduction angle Iang2 ≧ 140 °, the leakage magnetic flux amount 13 is obtained. The maximum leakage magnetic flux amount Δφmax2 of the leakage magnetic flux amount 13 is Δφmax2 ≦ Δφmax. Therefore, the leakage magnetic flux amount of the motor 5 can be suppressed to the leakage magnetic flux amount limit value 14 or less.

As shown in the graph of FIG. 2B, if the leakage magnetic flux amount is calculated in advance for each current conduction angle,
It is possible to accurately calculate the leakage magnetic flux amount from the armature current of the motor 5. The calculation of the amount of magnetic flux leakage can be performed strictly using magnetic field analysis by the finite element method. If the geometrical and electrical specifications of the motor 5 are determined, the leakage magnetic flux amount of the motor 5 is also uniquely determined. Therefore, the leakage magnetic flux amount-armature current characteristic is numerically analyzed using the current conduction angle as a parameter, and The analysis value is stored in advance in the leakage magnetic flux amount estimating means 6.

In this way, the amount of leakage magnetic flux can be accurately determined easily by the armature current 7 of the motor 5, so that the current conduction angle at which the leakage magnetic flux amount becomes equal to or less than the predetermined leakage magnetic flux amount is set to the current conduction angle setting means 2 Can be set with. Specifically, in the current conduction angle setting means 2, the leakage magnetic flux amount estimation means 6
The calculated leakage magnetic flux value and the reference leakage magnetic flux amount limit value 14 are constantly compared with each other, and if the leakage magnetic flux calculated value exceeds the leakage magnetic flux amount limit value 14, the current conduction angle is increased. On the contrary, when the calculated leakage flux becomes smaller than the leakage flux limit value 14, the current conduction angle is reduced. In this way, regardless of the armature current of the motor 5, the leakage magnetic flux amount of the motor 5 can be maintained below a predetermined value (here, the leakage magnetic flux amount limit value 14).

(Second Explanation of Leakage Magnetic Flux Calculation Method) As a second method of calculating the leakage flux quantity, a method of calculating the leakage flux quantity by PWM duty and DC voltage will be explained. Figure 1
(C) shows the amount of leakage magnetic flux of the motor 5 with the DC voltage 8 and the PWM.
It is calculated by the duty 9. The DC voltage 8 of the DC / AC converting means 4 and the PWM duty 9 of the PWM duty controlling means 3 are taken into the leakage magnetic flux amount estimating means 6, the leakage magnetic flux amount estimating means 6 calculates the leakage magnetic flux amount, and the calculated value is passed through the current. Output to the angle setting means 2. The operation of the current conduction angle setting means 2 is the same as the content described in the first method of calculating the leakage magnetic flux amount.

As shown in FIG. 5A, the armature current-PWM duty characteristic of the motor 5 is such that the DC voltage 8 is equal to VDC.
Then, theoretically, the electric currents 21 to 23 are obtained. Here, V1>V0>V2> 0 and inverter frequency f1 = f0 (constant value). From the characteristic diagram shown in FIG. 5A and the characteristic diagram shown in FIG. 2B, the characteristic diagram shown in FIG. 5B and the characteristic diagram shown in FIG.
And the characteristic diagram shown in FIG. Note that FIG. 5B shows the current conduction angle = Iang1, and FIG. 5C shows the current conduction angle = Iang2.

Based on the result of numerical analysis of the leakage magnetic flux amount-armature current characteristic using the current conduction angle as a parameter, the leakage magnetic flux amount-PWM duty characteristic is measured with the DC voltage and the current conduction angle as parameters. Store in 6. Then, the DC voltage 8 of the DC / AC converting means 4 and P
With the PWM duty 9 of the WM duty control means 3, the leakage magnetic flux amount estimating means 6 calculates the leakage magnetic flux amount, and outputs the calculated value to the current conduction angle setting means 2. By doing so, the amount of leakage magnetic flux of the motor 5 can be easily determined accurately, so that the current conduction angle can be set by the current conduction angle setting means 2 so that the current conduction angle becomes equal to or less than the predetermined leakage magnetic flux amount.

A method for changing the current conduction angle of the current conduction angle setting means 2 shown in FIGS. 1A to 1C will be described below. FIG. 6 shows an outline of this changing method. Current conduction angle 1
The change method shown by 1 changes the current conduction angle continuously and discretely, and the current conduction angle changes smoothly. Therefore, it is suitable for applications where it is desired to reduce noise and vibration as much as possible. Further, the changing method indicated by the current conduction angle 30 is to change the current conduction angle in steps, and the current conduction angle is changed in steps. This reduces the calculation load of the control system, so noise and vibration can be reduced to the standard level, but the memory capacity of ROM, RAM, etc. in the control configuration is reduced, and the cost is reduced by using the low-speed CPU. It can be carried out.

FIG. 7 shows a motor drive device according to the present invention.
FIG. 7 is an operation diagram in the case of being applied as a torque control device for a one-piston rotary compressor and controlling the electromagnetic torque generated by the brushless DC motor in response to the rotational load torque fluctuation of the one-piston rotary compressor. FIG. 7 is a diagram showing various quantities with respect to the rotor rotation angle of the motor 5 incorporated in the one-piston rotary compressor. Since the load torque of the one-piston rotary compressor changes like the load torque 31, the output torque of the motor 5 also needs to change like the output torque 33. At this time, the PWM duty output by the PWM duty control means 3 is approximately PW.
It becomes like the M duty 34. Further, the armature current of the motor 5 becomes the armature current 32, and the current value comes to fluctuate periodically.

In such a case, in the case of the method described above, the calculated value of the leakage magnetic flux amount of the leakage magnetic flux amount estimating means 6 also changes in accordance with the period variation, so the current conduction angle of the current conduction angle setting means 2 is changed. The output value also fluctuates. However, when the periodic load fluctuation can be predicted, the current conduction angle by the current conduction angle setting means 2 does not have the periodic variation, and the armature peak current 35 which is the peak current of the armature current 32.
It is preferable to fix the current conduction angle corresponding to the above so that the current conduction angle does not change periodically.

Basically, by increasing the current conduction angle in the operating region where the torque control is required and decreasing the current conduction angle in the operating region where the torque control is not required, the magnetic saturation during the torque control is reduced. Therefore, it is possible to suppress the driving vibration and the driving noise, improve the motor driving efficiency, and suppress the armature current. Therefore, a switching element having a small current capacity, low cost, and a small space can be used, and the performance and cost merit of the one-piston rotary compressor can be maximized. Although one embodiment of the present invention has been described above, it goes without saying that various other embodiments are possible without departing from the scope of the present invention.

[0045]

According to the first aspect of the present invention, a leakage magnetic flux amount estimating means for calculating the leakage magnetic flux amount on the basis of a predetermined electrical physical quantity, and an electric machine for controlling the calculated leakage magnetic flux amount to a predetermined value or less. Since it has a current conduction angle setting means for controlling the current conduction angle of the child current, it is possible to drive the motor at a current conduction angle that matches the load torque and reduce the amount of leakage magnetic flux to bring out the original performance of the motor. it can. Therefore, a motor having an extremely small volume can be used, and the cost of the motor drive device can be reduced.

According to the second invention of the present application, since the amount of leakage magnetic flux is calculated by the armature current, a special magnetic detection device for detecting the leakage magnetic flux is not required, and the cost of the motor drive device can be reduced. You can

According to the third invention of the present application, since the amount of leakage magnetic flux is calculated by the DC voltage and the PWM duty, a current sensor or the like for detecting the armature current is not required, and the cost of the motor drive device can be reduced. It can be achieved further.

According to the fourth aspect of the present invention, since the current conduction angle is set according to the load torque, 120 ° when the load is light.
By the energization drive, very good robust controllability, speed control performance, speed followability and control stability can be secured. Further, since the current conduction angle is increased when the load is heavy, the amount of leakage magnetic flux inside the motor can be suppressed to a predetermined value or less, and the original torque withstanding performance of the motor can be exhibited.

According to the fifth aspect of the present invention, if the current-carrying angle is appropriately set according to the application of the motor drive device, the speed followability, speed response, control stability and torque withstanding performance can be improved at a high level. A low cost motor can be used while balancing.

According to the sixth aspect of the present invention, since the one-piston rotary compressor can be driven with low vibration or low noise, the high efficiency and low cost of the one-piston rotary compressor are fully exhibited. be able to.

According to the seventh aspect of the present invention, since the magnetic saturation phenomenon during torque control can be suppressed, the motor drive efficiency during torque control is improved. Furthermore, since the armature current can also be suppressed, it is possible to use a switching element having a small current capacity, low cost, and a small space, which reduces the cost of the entire motor drive device, suppresses heat generation, saves energy, and downspaces. Can contribute to realization.

According to the eighth aspect of the present invention, when the load fluctuates cyclically, the current conduction angle is prevented from fluctuating cyclically, so that the control stability of the armature current during torque control jumps. And has a great effect on suppression of vibration, noise, and current, and it is possible to further increase the added value of the motor drive device.

According to the ninth aspect of the present invention, the method of changing the current conduction angle can be selected according to the application of the motor drive device. Then, according to the continuous discrete method, the current conduction angle changes smoothly, and the operating noise and the operating vibration of the motor drive device / load device can be further reduced.
Further, in the case of the step change, the control calculation load is lightened, the ROM and RAM capacities can be reduced, and a low-cost low-speed calculation microcomputer can be used. Therefore, the cost of the motor drive device can be reduced. It is possible to further improve the cost performance.

[Brief description of drawings]

FIG. 1A is a control block diagram (basic configuration diagram) of a motor drive device according to an embodiment of the present invention, and FIG.
And (c) are diagrams showing a first leakage magnetic flux amount calculation method and a second leakage magnetic flux amount calculation method in the motor drive device shown in (a), respectively.

2A and 2B are a current conduction angle characteristic diagram and a leakage magnetic flux amount characteristic diagram in the first leakage magnetic flux amount calculation in the motor drive device according to the present invention, respectively.

FIG. 3 is an armature current distortion rate-current conduction angle characteristic diagram.

FIG. 4 is a leakage magnetic flux amount-current conduction angle characteristic diagram.

5 (a), (b) and (c) are respectively an armature current characteristic diagram, a first leakage flux amount characteristic diagram and a second leakage flux amount characteristic diagram in the second leakage flux amount calculation in the motor drive device according to the present invention. It is a 2nd leakage magnetic flux amount characteristic diagram.

FIG. 6 is a diagram illustrating a method of changing a current conduction angle.

FIG. 7: Armature current, output torque, load torque and P
It is a figure which shows the change of WM duty.

FIG. 8 is a diagram illustrating a change in current conduction angle.

FIG. 9 is a block diagram of a conventional motor drive device.

[Explanation of symbols]

1 ... Magnetic pole position detecting means, 2 ... Current conduction angle setting means, 3 ...
PWM duty control means, 4 ... DC / AC conversion means, 5
... 3-phase brushless DC motor, 6 ... Leakage magnetic flux amount estimating means, 7 ... Armature current, 8 ... DC voltage, 9 ... PWM duty, 10 ... Current conduction angle, 11 ... Current conduction angle, 12 ... Leakage magnetic flux amount, 13 ... Leakage magnetic flux amount, 14 ... Leakage magnetic flux amount limit value, 15 ... Armature current distortion rate, 16 ... Characteristic intersection, 17
... Armature current distortion rate limit value, 18 ... Leakage magnetic flux amount, 19 ...
Characteristic intersection, 21 ... Armature current, 22 ... Armature current, 2
3 ... Armature current, 24 ... Leakage flux amount, 25 ... Leakage flux amount, 26 ... Leakage flux amount, 27 ... Leakage flux amount, 28 ... Leakage flux amount, 29 ... Leakage flux amount, 30 ... Current conduction angle, 31 ...
Load torque, 32 ... Armature current, 33 ... Output torque, 3
4 ... PWM duty, 35 ... Armature peak current, 36
... current conduction angle, 101 ... magnetic pole position detection means, 103 ... P
WM duty control means, 104 ... DC / AC conversion means,
105 ... 3-phase brushless DC motor.

Claims (9)

[Claims] 1. A direct current alternating current including a switching element, converting the direct current voltage into a desired pseudo alternating voltage by opening and closing the switching element according to a control signal, and outputting the pseudo alternating voltage to a three-phase brushless DC motor. The conversion means, the magnetic pole position detection means for detecting the rotation phase obtained from the induced voltage of the three-phase armature winding of the three-phase brushless DC motor, and outputting the rotation phase information, and the switching element of the DC / AC conversion means. And a PWM duty control means for outputting a control signal for PWM controlling the opening / closing operation of the three-phase brushless DC motor connected between the magnetic pole position detection means and the PWM duty control means. The amount of leakage magnetic flux due to the action of the armature current between the stator and the rotor inside is based on the specified electrical physical quantity. And a current conduction angle setting means for controlling the current conduction angle of the armature current so that the leakage magnetic flux amount calculated by the leakage magnetic flux amount estimating means becomes equal to or less than a predetermined value. A motor drive device having. 2. The motor drive device according to claim 1, wherein the predetermined electrical physical quantity is an armature current. 3. The motor drive device according to claim 1, wherein the predetermined electrical physical quantity is a DC voltage and a PWM duty. 4. The current conduction angle setting means increases the current conduction angle when the calculated leakage magnetic flux amount exceeds a predetermined value, and increases the current conduction angle when the leakage magnetic flux amount decreases below a predetermined value. The motor drive device according to any one of claims 1 to 3, characterized in that 5. The motor drive device according to claim 1, further comprising a current conduction angle setting means for setting the current conduction angle to 120 degrees or more and less than 180 degrees. 6. A PWM duty control means, which is applied to a torque control device for a one-piston rotary compressor, and which controls the electromagnetic torque generated by the three-phase brushless DC motor in response to fluctuations in rotational load torque of the one-piston rotary compressor. The motor drive device according to claim 1, further comprising: 7. A current energizing device applied to a torque control device for a one-piston rotary compressor, wherein a current energizing angle is increased in an operating region where torque control is required, and a current energizing angle is reduced in an operating region where torque control is not required. The motor drive device according to claim 6, further comprising angle setting means. 8. An amount of leakage magnetic flux inside the three-phase brushless DC motor, which is fixed to a current conduction angle corresponding to only the maximum current in one cycle of the armature current with respect to periodic fluctuations of the armature current. 7. The motor drive device according to claim 6, further comprising a current conduction angle setting unit that sets the current to a predetermined value or less. 9. The motor drive device according to claim 1, further comprising a current conduction angle setting means for changing the current conduction angle in a continuous discrete or stepwise manner.