JP2007221867A - Motor controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor controller in which operation performance is enhanced. <P>SOLUTION: The motor controller comprises a DC/AC conversion means for converting a DC voltage into an AC voltage by opening/closing a switching element based on a PWM signal and supplying the AC voltage to a three-phase brushless DC motor, a means 1 for detecting induction voltage of the three-phase brushless DC motor, a means 8 for detecting a regeneration voltage included in the induction voltage, a means 2 for judging the magnetic pole position based on the regeneration voltage and the induction voltage, a voltage control means 3 outputting a voltage waveform based on the magnetic pole position output from the magnetic pole position detecting means 2, and a PWM control means 5 for converting the voltage waveform into a PWM signal. The motor controller is further provided with a means 40 for controlling the conduction angle of voltage waveform of the voltage control means 3 based on a physical value related to the number of detection times of the regeneration voltage detection means 8, and the DC current. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a motor control device that controls the frequency of a brushless DC motor.

  Conventionally, there are a 120 ° energization control method and a sine wave 180 ° energization control as motor control devices for controlling the rotational speed of a brushless DC motor. FIG. 6 shows a control block diagram of the conventional motor control device.

  The 120 ° energization method is a method of directly detecting the zero-cross signal of the induced voltage, and is obtained by comparing the inverter phase voltage with the reference voltage in order to detect it. The commutation signal is changed based on this zero cross signal. This zero cross signal is generated 12 times during one rotation of the motor, and is generated every 30 ° mechanical angle, that is, every 60 ° electrical angle (see, for example, Patent Document 1).

The 180 ° energization method amplifies the differential voltage between the neutral point potential of the motor winding and the neutral point potential of the three-phase Y-connected resistor to the three-phase inverter output voltage, and inputs it to the integration circuit The position detection signal corresponding to the induced voltage is obtained by comparing the output signal of the integration circuit with the low-pass signal obtained by processing the output signal with a filter circuit and cutting the direct current. This position detection signal is generated 12 times during one rotation of the motor, and is generated every 30 ° mechanical angle, that is, every 60 ° electrical angle. In this method, phase correction control is required to pass through an integration circuit (see, for example, Patent Documents 2 and 3).
Japanese Patent Laid-Open No. 1-8890 JP 7-245982 A Japanese Patent Laid-Open No. 7-337079

  However, since the conventional 120 ° energization method compares the zero crossing of the induced voltage portion, the zero cross signal of the induced voltage is hidden in the inverter output voltage region when the motor load sudden change or the power supply voltage sudden change occurs. Therefore, it may become impossible to detect. In such a state, first, a step-out phenomenon occurs and the inverter system stops.

  In addition, at 120 ° energization, the induced voltage per phase can be confirmed continuously for 60 ° electrical angle, but in order to reduce the noise and vibration during motor operation, the energization angle is set to about 150 ° for operation. If this is the case, the induced voltage per phase can only be confirmed continuously for an electrical angle of 30 °, and the risk of step-out increases due to the effect of the inverter regenerative voltage even during normal operation, and unstable phenomena such as turbulence occur. There was a tendency to occur easily.

  Further, the conventional configuration has a problem that an operation close to 180 ° energization is impossible.

  FIG. 8A is a relationship diagram between the phase current waveform and the induced voltage waveform of 120 ° energization control. During normal operation, the phase current 20 is set to the position of the induced voltage 10 and when the maximum rotation speed is increased, the phase current 20 needs to be advanced, but the limit is fast and the high-speed rotation performance is inferior.

FIG. 8B is a relationship diagram between the phase current waveform and the induced voltage waveform in the 180 ° energization control. 180
Since the energization method passes through the integration circuit, the zero cross position of the induced voltage cannot be accurately grasped in absolute value, and the phase difference between the zero cross position and the position detection signal varies greatly depending on the operating state. Complicated control such as correction is required, and the phase correction adjustment is difficult, and the control calculation is complicated.

  Further, the motor requires a neutral point output terminal, and uses the third harmonic component of the induced voltage waveform, and therefore has a problem that it cannot be used in a motor using a sine wave magnetized magnet.

  In addition, in the sensorless sine wave 180 ° energization drive control by the current feedback method, the motor magnetic pole position is estimated and calculated by the motor current and the motor electrical constant, so the calculation error becomes large, and the limit point of the motor current advance control is There was a problem that the maximum number of rotations was not far from control with a position sensor.

  The present invention solves the above-mentioned conventional problems, and realizes high-speed performance equivalent to 180 ° sine wave conduction with a position sensor by a new method of induced voltage feedback control that does not require a mechanical electromagnetic pickup sensor, It is another object of the present invention to provide a motor control device that can further improve the step-out limit torque in any operating load region and that is inexpensive and highly reliable.

  The present invention includes a plurality of switching elements, a DC / AC converting means for converting a DC voltage into an AC voltage based on a PWM signal by opening and closing the switching elements and supplying the AC voltage to a three-phase brushless DC motor, and the three-phase brushless DC motor. An induced voltage detecting means for detecting an induced voltage of the magnetic field, a regenerative voltage detecting means for detecting a regenerative voltage included in the induced voltage, and a magnetic pole position detecting means for determining the magnetic pole position based on the regenerative voltage and the induced voltage. Voltage control means for outputting a voltage waveform based on the magnetic pole position output from the magnetic pole position detection means, and PWM control means for converting the voltage waveform into the PWM signal, and the regenerative voltage detection means An energization angle control means for controlling the energization angle of the voltage waveform of the voltage control means based on the number of times of regenerative detection and a physical quantity related to DC current And it is characterized in and.

  As a result, the energization angle can be finely controlled in accordance with the change of the direct current, so that step-out can be prevented and the operation assurance of the motor control device can be improved.

  According to the present invention, it is possible to control to the optimum current conduction angle according to the motor characteristics and operation application while avoiding the step-out phenomenon due to the regenerative voltage, and also to control responsiveness and control stability against large DC current fluctuations.・ Control reliability is improved, and a motor controller that can handle a wide range of operating loads can be provided.

A first invention includes a plurality of switching elements, DC / AC converting means for converting a DC voltage into an AC voltage based on a PWM signal by opening and closing the switching elements and supplying the AC voltage to a three-phase brushless DC motor, and the three-phase brushless Inductive voltage detecting means for detecting an induced voltage of a DC motor, regenerative voltage detecting means for detecting a regenerative voltage included in the induced voltage, and magnetic pole position for determining the magnetic pole position based on the regenerative voltage and the induced voltage Detection voltage; voltage control means for outputting a voltage waveform based on the magnetic pole position output from the magnetic pole position detection means; and PWM control means for converting the voltage waveform into the PWM signal, the regenerative voltage detection. An energization angle control means for controlling the energization angle of the voltage waveform of the voltage control means on the basis of the number of regenerative detections of the means and a physical quantity related to the direct current. By the, can be controlled finely conduction angle in response to a change in DC current can be prevented and loss of synchronism, it is possible to improve the operation guarantee of the motor control device.

  According to a second aspect of the present invention, particularly in the first aspect, the energization angle control means reduces the energization angle when the DC current change rate is large, and increases the energization angle when the DC current change rate is small. Since the energization angle can be controlled according to the direct current change rate, a more stable control system can be constructed.

  In the third aspect of the invention, in particular in the second aspect of the invention, the energization angle control means can control the energization angle finely according to the direct current change rate by using a linear function expression of the direct current change rate, so that it is more stable. A control system can be constructed.

  According to a fourth aspect of the present invention, in the first aspect of the invention, the energization angle control means reduces the energization angle when the DC current ripple rate is large, and increases the energization angle when the DC current ripple rate is small. Since the energization angle can be controlled according to the DC current ripple rate, a more stable control system can be constructed.

  In the fifth aspect of the invention, in particular in the fourth aspect of the invention, the energization angle control means can control the energization angle finely according to the DC current ripple rate by adopting a linear function formula of the DC current ripple rate. A control system can be constructed.

  According to a sixth aspect of the present invention, in the first aspect of the invention, the energization angle control means reduces the energization angle when the DC current average value is large, and increases the energization angle when the DC current average value is small. Since the energization angle can be controlled according to the direct current average value, a more stable control system can be constructed.

  In the seventh aspect of the invention, particularly in the sixth aspect of the invention, the energization angle control means can control the energization angle finely according to the DC current average value by adopting a linear function equation of the DC current average value. A control system can be constructed.

  In the eighth invention, in particular, in the third, fifth, and seventh inventions, the linear function formula has an upper limit value and a lower limit value, thereby limiting the conduction angle, so that a more stable control system can be constructed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
Embodiments of a motor control device according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows a control block diagram of the motor control device of the present embodiment. The motor control device of the present embodiment is a motor control device that controls the rotation speed of the three-phase brushless DC motor 7. In this figure, the motor control device converts a DC voltage 4 into an AC voltage and outputs it to a three-phase brushless DC motor (hereinafter abbreviated as BLM) 7 and an induction for detecting an induced voltage of the BLM 7. A voltage detection means 1; a magnetic pole position detection means 2 for detecting the magnetic pole position of the brushless DC motor from the induced voltage; a voltage control means 3 for outputting a voltage waveform based on the magnetic pole position output from the magnetic pole position detection means 2; PWM control means 5 for converting a voltage waveform into a PWM signal, regenerative voltage detection means 8 for detecting a regenerative voltage included in the induced voltage, and a magnetic pole position for determining a magnetic pole position based on the detected regenerative voltage and the induced voltage And detecting means 2.

  The PWM control means 5 outputs a PWM signal for controlling the applied voltage, frequency, and phase for controlling the rotation speed of the BLM 7. The DC / AC converting means 6 includes six switching elements (FIG. 2A) that open and close at high speed.

  First, the roles of the induced voltage detection means 1, the magnetic pole position detection means 2, the voltage control means 3, and the PWM control means 5 will be described sequentially in FIG. This part is the same as the operation of the control block diagram of the conventional motor control device in FIG.

  In FIG. 1, the induced voltage detection means 1 lowers the induced voltage of the BLM 7, the magnetic pole position detection means 2 detects the induced voltage zero cross signal, and outputs the induced voltage zero cross signal to the voltage control means 3 as the magnetic pole position. Based on the magnetic pole position, the voltage control means 3 calculates a voltage waveform for driving the BLM 7 and outputs it to the PWM control means 5. Based on the voltage waveform, the PWM control means 5 outputs a PWM signal to the DC / AC conversion means 6. In the motor control apparatus configured as described above, the rotation speed of the BLM 7 is controlled by changing the frequency and phase (hereinafter referred to as “inverter frequency”) of the AC voltage output from the DC / AC conversion means 6. .

  In the case of 120 ° energization control, the PWM control means 5 outputs six types of PWM signals for opening and closing the switching elements of the DC / AC conversion means 6, and the switching elements are opened and closed by the six kinds of PWM signals. The inverter frequency output from the AC conversion means 6 is controlled.

  Six kinds of PWM signals will be described. The six types of PWM signals are pulse signals for driving the switching elements of the DC / AC converter 6. The PWM signal has six basic patterns PTN1 to PTN6 in one cycle of the inverter electrical angle, and the reciprocal of one cycle of the PWM signal is the inverter frequency.

  Actually, the method for changing the rotation speed of the BLM 7 is that the PWM control means 5 controls the rotation speed of the BLM 7 while changing the inverter frequency of the DC / AC conversion means 6.

  As shown in FIG. 2 (a), the DC / AC converting means 6 has six switching elements. For the U-phase, V-phase, and W-phase, one switching element is provided in the upper arm and the lower arm is switched. One element is provided.

  In PTN1, the U-phase upper arm switching element Tu and the V-phase lower arm switching element Ty are energized.

  In PTN2, the U-phase upper arm switching element Tu and the W-phase lower arm switching element Tz are energized.

  In PTN3, the V-phase upper arm switching element Tv and the W-phase lower arm switching element Tz are energized.

  In PTN4, the V-phase upper arm switching element Tv and the U-phase lower arm switching element Tx are energized.

  In PTN5, the W-phase upper arm switching element Tw and the U-phase lower arm switching element Tx are energized.

  In PTN6, the W-phase upper arm switching element Tw and the V-phase lower arm switching element Ty are energized.

  The commutation switching of the PWM signal is performed based on the voltage waveform output of the voltage control means 3.

  The detailed operation of the magnetic pole position detecting means 2 will be described with reference to FIG. 2B and FIGS. The induced voltage zero cross signal of the BLM 7 is generated six times during one electrical angle cycle. FIG. 3A shows the induced voltage zero-cross signal per phase. FIG. 3A is a relationship diagram of the phase current waveform and the phase induced voltage waveform, and shows the induced voltage 10, the phase current 9, the positive zero cross signal 11 and the reverse zero cross signal 12. The positive zero cross signal 11 is generated at an electrical angle of 0 °, and the reverse zero cross signal 12 is generated at an electrical angle of 180 °. The induced voltage that can be actually observed by the magnetic pole position detecting means 2 is the induced voltage 10a in FIG. 3B and the induced voltage 10b in FIG. 4B if the negative side of the DC voltage 4 is the GND potential N. This means that the line voltage of the BLM 7 is observed. If the induced voltage near the zero cross signal is considered, the waveform of the induced voltage 10 is superimposed on the PWM voltage component. . Basically, the intersection of the half of the DC voltage VDC (= VDC / 2) and the induced voltage 10a (10b), and further the conduction point of each of the upper and lower arm elements of the DC / AC converting means 6 is one. The positive zero cross signal 11 (reverse zero cross signal 12) can be detected during the arcing period (TON portion in FIGS. 3 and 4).

  The magnetic pole position detection means 2 detects the positive zero cross signal 11 and the reverse zero cross signal 12 in the figure, and outputs them to the voltage control means 3 as the magnetic pole position. Based on the zero cross signal, the voltage control means 3 calculates a voltage waveform substantially similar to the phase current 9, and the PWM control means 5 creates a PWM signal base PTN corresponding to each electrical angle based on the voltage waveform. To do. The electrical angles X1 to X2 in FIG. 3 and the electrical angles X3 to X4 in FIG. 4 are current cut sections. Further, the voltage control means 3 can create a voltage waveform of a 120 ° to 180 ° energization waveform. However, in order to observe the induced voltage, it is necessary to make the conduction angle less than 180 °.

  When the conduction angle> 120 °, in addition to the six PWM signals described in the 120 ° conduction control, a three-phase sine wave drive PWM signal is added. Basically, a PWM signal for 120 ° energization control is used in a section where the current is OFF in any one of the three phases (≡current cut section). In the section where the phase current flows in all three phases, the PWM signal for three-phase sine wave drive is used. Since this PWM signal is already known as three-phase sine wave PWM control, detailed description thereof is omitted here.

  The voltage waveform output by the voltage control means 3 is almost similar to that of the phase current 9, but the phase difference is somewhat advanced with respect to the phase current 9. In this embodiment, for simplification, the phase difference will be described as zero. That is, voltage waveform ≡phase current 9 is defined.

  FIG. 9 is an equivalent circuit diagram of the BLM7. R1 is the primary resistance of the winding, Lu · Lv · Lw is the inductance of each phase, and Eu · Ev · Ew is the field induced voltage of each phase. Here, the field induced voltage means an induced voltage generated only by a magnet (field) when the BLM 7 rotates in a non-energized state. FIG. 2B is a field induced voltage waveform relationship diagram of the three-phase brushless DC motor. In the figure, U1 represents the positive zero cross position of Eu, and U2 represents the reverse zero cross position. Similarly, the other phases are also shown, and the interval between the zero cross positions is ideally generated 6 times every 60 ° and one cycle of the electrical angle. These zero-cross positions are named as the true magnetic pole positions of the BLM7.

  The true magnetic pole position of the BLM 7 cannot be determined directly from the zero cross signal of the induced voltage 10 due to the influence of the armature reaction, and a phase difference occurs between the two. Further, since this phase difference depends on the operating load, it is difficult to specify the true magnetic pole position from the induced voltage zero cross signal. However, even if the true magnetic pole position cannot be specified, it is sufficiently possible to control the rotation speed of the BLM 7 only by the induced voltage zero cross signal, and it may be preferable to control by the induced voltage. In the present embodiment, description will be made assuming that the phase difference between the two is zero. That is,

It is. That is, if the induced voltage 10 in FIG. 3A corresponds to the U phase,

It is. In addition,

It is. The above equation is generated because the voltage waveform amplitudes of both are different due to the influence of the armature reaction.

  Next, the detailed operation of the regenerative voltage detection means 8 will be described with reference to FIGS. Generally, as a condition for generating the regenerative voltage, the regenerative voltage is generated continuously for a predetermined time from the moment when the phase current of the BLM 7 is cut, and then the original induced voltage is generated. The output of the induced voltage detection means 1 includes both the regenerative voltage and the induced voltage, and both need to be distinguished. If this determination is wrong, the regenerative voltage portion is erroneously detected as a zero-cross signal of the induced voltage, and abnormal phenomena such as turbulence and step-out occur.

  FIG. 3B and FIG. 4B show the relationship between the regenerative voltage and the induced voltage. FIG. 3 shows a case where the time differential value is positive as the induced voltage 10, and FIG. 4 shows a case where the time differential value is negative as the induced voltage 10. In the figure, the regenerative voltage 13 and the regenerative voltage 14 are generated from the moment when the phase current 9 is cut and continue to the regenerative voltage end point 19 and the regenerative voltage end point 22. As one of the necessary conditions for determining the positive zero cross signal 11,

As one of the necessary conditions for determining the reverse zero cross signal 12,

There is. However, since the voltage value of the regenerative voltage 13 is VDC before the positive zero cross signal 11 is detected, the relationship of the above equation is already satisfied and erroneous detection occurs. In order to prevent this, in the position detection in the figure, if the position detection result is ignored before the regenerative voltage end point 19 and the position detection determination is started after the regenerative voltage end point 19, the regenerative voltage 13 is supplied to the positive zero cross signal 11. As a false positive.

  Similarly, in the case of the reverse zero cross signal 12, the voltage value of the regenerative voltage 14 is 0 V, which already satisfies the relationship of the above equation and erroneously detects. In order to prevent this, the determination of the position detection section in the figure is started after the regenerative voltage end point 22. Thus, the regenerative voltage detecting means 8 outputs the regenerative voltage end point 19 and the regenerative voltage end point 22 to the magnetic pole position detecting means 2 as a regeneration end signal, and the magnetic pole position detecting means 2 receives the regenerative voltage until receiving the signal. 13. Ignore position detection of regenerative voltage 14. If the signal is received, determination of position detection is started, so that the original positive zero cross signal 11 and reverse zero cross signal 12 can be determined.

  The regenerative voltage detection means 8 has a VTH1 regenerative determination reference voltage 17 and a VTH2 regenerative determination reference voltage 18 inside, and makes a determination by comparing the value with the regenerative voltage 13 and the regenerative voltage 14. In particular

And

It is a real number that satisfies The regenerative voltage coefficient may be set appropriately. The regenerative voltage detection means 8 samples the regenerative voltage 13 and the regenerative voltage 14. That is, the regeneration detection point 15 and the regeneration detection point 16. The regenerative voltage detection means 8 performs voltage sampling from the electrical angles X1 and X3, which are current cut start points, and obtains the voltage Vij between the regenerative detection point 15 and the regenerative detection point 16. This voltage Vij will be described with reference to FIG.

  FIG. 5 illustrates the voltage sampling operation of the regenerative voltage detection means 8. T = 0 in the figure corresponds to the electrical angles X1 and X3 of the current cut start point. From T = 0, the regenerative voltage detection means 8 starts sampling the induced voltage of the induced voltage detection means 1 (which is still the regenerative voltage at this time), and the regenerative voltage end point 19 and the regenerative voltage end point 22 at which the regenerative voltage ends. Thus, a regeneration end signal is generated for the magnetic pole position detecting means 2. From T = 0, a Vij regeneration detection point 30 that is a regenerative voltage acquisition at time Tij31 intervals is acquired,

The regenerative voltage is determined every time. Here, i and j are arbitrary natural numbers. When judging the regenerative voltage,

And the regenerative voltage is determined by comparing Vi with VTH1 or VTH2. That is, in the case of FIG.

In the case of FIG.

If so, Vi is regarded as a regenerative voltage. While the above condition is satisfied, the magnetic pole position detecting means 2 ignores all the position detection results. When the above condition is not satisfied, the regenerative voltage detecting means 8 sends a regeneration end signal to the magnetic pole position detecting means 2, and the magnetic pole position detecting means 2 receives the signal to detect the position. Start judgment. The magnetic pole position detection means 2 obtains the positive zero cross signal 11 and the reverse zero cross signal 12 according to the conventional determination criterion described above when the regeneration end signal is received. When the position determination is finished, the current cut is finished at the electrical angle X2 after the elapse of the wait time in FIGS. 3 and 4, and phase commutation (switching of the base PTN) is performed.

  Next, the operation of the conduction angle control means 40 will be described. The energization angle control unit 40 adjusts the energization angle based on the number of regeneration detections NRCV determined by the regenerative voltage detection unit 8 and outputs the energization angle to the voltage control unit 3. In the voltage control means 3, the electrical angle X1 and the electrical angle X3, which are current cut start angles in FIGS. 3 and 4, are increased or decreased based on the energization angle. Specifically, when the energization angle value is increased, X1 · X3 is increased (the current cut start is delayed), and when the energization angle value is decreased, X1 · X3 is decreased (the current cut start is advanced). The voltage control means 3 outputs the voltage waveform thus obtained to the PWM control means 5.

  The regeneration detection frequency NRCV will be described. As described above, from T = 0 in FIG. 5, the regenerative voltage is taken at time Tij31 intervals, and the regenerative detection point 30Vij is acquired. And

The regenerative voltage is determined every time. Here, i and j are arbitrary natural numbers. When judging the regenerative voltage,

And the regenerative voltage is determined by comparing Vi with VTH1 or VTH2. That is, in the case of FIG.

In the case of FIG.

It is. Further, NRCV ≧ 0 is satisfied. Then, it switches to the next base pattern, and again at time T = 0 after the start of the current cut start angle,

It becomes. The initial value after power-on is also NRCV = 0. It is considered that the energization angle is controlled using this regenerative detection number NRCV. Basically, if the NRCV increases, the time region of the regenerative voltage 13 increases when taking FIG. 3 as an example. Accordingly, the time interval between the regenerative voltage end point 19 and the positive zero cross signal 11 is shortened. Naturally, the regenerative voltage end point 19 cannot be detected accurately and accurately unless the position is advanced in time with respect to the positive zero cross signal 11, and exhibits an unstable behavior. Further, if a stable motor control device is constructed, it is necessary to secure a time interval from the regenerative voltage end point 19 to the positive zero cross signal 11 to some extent. As a technique for realizing this, the electrical angle X1 may be reduced and accelerated as NRCV increases. Moreover, if NRCV becomes small, the electrical angle X1 should be enlarged and delayed. That is,

It is. When expressed in mathematical formula, a constant value NRCV0 (≧ 0) is defined,

Considering that, if the conduction angle is IANG,

It is. here,

It is. An image of the above equation is shown in FIG. As shown by the conduction angle value 32 (shown as IG in the figure) in this figure,

Also,

Is provided with a limiter at the conduction angle IANG. During normal operation,

Meet. Here, m0 is a natural number.

  On the other hand, when the conduction angle is changed in the conduction angle control means 40 in accordance with the temporal change of the current average value, current change rate, and current ripple rate of the direct current IDC, the controllability is further improved. If the current change rate absolute value of the DC current IDC is σI (≧ 0) and the current ripple rate is ξI (≧ 0),

Or

You can use mathematical expressions. here,

It is a real number that satisfies Moreover, it is better to set an upper limit value and a lower limit value for the energization angle obtained from the above formulas,

Set in the real number range that satisfies. If the maximum value of DC current is IDMAXAX, the minimum value is IDCMIN, and the average value is IDCAVE,

The relationship is established.

  The meaning of the conduction angle 1 is to reduce the conduction angle when the DC current average value / DC current change rate increases. In this case, if the DC current average value / DC current change rate is large and the energization angle is large, it is difficult to detect the zero-cross position of the induced voltage and the control system tends to become unstable. It works to make it easier to detect the zero-cross position. The meaning of the energization angle 2 is to decrease the energization angle as the DC current average value / DC current ripple rate increases. When the DC current average value / DC current ripple ratio increases, it becomes difficult to detect the zero-cross position of the induced voltage. Conversely, when the DC current average value, DC current change rate, and DC current ripple rate are small, the energization angle can be increased. The conduction angle control of the conduction angle control means 40 can further improve the control stability against fluctuations in the DC current, and also prevent erroneous detection of the regenerative voltage and accurately capture the zero-cross position of the induced voltage. Is possible.

  Although the present embodiment has been described by taking a three-phase brushless DC motor as an example, the concept is the same for application to a single-phase brushless DC motor, and the scope does not depart from the spirit, concept, and claims of the present invention. Of course, it is possible to change, add, or delete the embodiment as appropriate.

  The motor control device according to the present invention can be applied to an inverter device for an air conditioner and the like because a motor control device with high operation reliability can be constructed even with respect to a current change.

Control block diagram of motor control apparatus of Embodiment 1 (A) Configuration diagram of DC / AC conversion means (b) Field-induced voltage waveform relationship diagram of three-phase brushless DC motor (A) Operation explanatory diagram of regenerative voltage detecting means (b) Operation explanatory diagram of regenerative voltage detecting means (A) Operation explanatory diagram of regenerative voltage detecting means (b) Operation explanatory diagram of regenerative voltage detecting means Operation explanatory diagram of regenerative voltage detection means Operation explanatory diagram of conduction angle control means Control block diagram of a conventional motor control device Relationship diagram between conventional phase current waveform and induced voltage waveform Equivalent circuit diagram of three-phase brushless DC motor

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Induced voltage detection means 2 Stage magnetic pole position detection means 3 Voltage control means 4 DC voltage 5 PWM control means 6 DC / AC conversion means 7 Brushless DC motor (BLM)
8 regenerative voltage detection means 9 phase current 10 induced voltage 11 positive zero cross signal 12 reverse zero cross signal 13 regenerative voltage 14 regenerative voltage 15 regenerative detection point 16 regenerative detection point 17 regenerative determination reference voltage 18 regenerative determination reference voltage 19 regenerative voltage end point 20 phase Current 21 Phase current 22 Regeneration voltage end point 30 Regeneration detection point 31 Regeneration detection time interval 32 Energization angle value 40 Energization angle control means 41 DC current detection means

Claims (8)

DC switching means including a plurality of switching elements, converting a DC voltage into an AC voltage based on a PWM signal by opening and closing the switching element and supplying the AC voltage to a three-phase brushless DC motor; and an induced voltage of the three-phase brushless DC motor An induced voltage detecting means for detecting; a regenerative voltage detecting means for detecting a regenerative voltage included in the induced voltage; a magnetic pole position detecting means for determining the magnetic pole position based on the regenerative voltage and the induced voltage; Voltage control means for outputting a voltage waveform based on the magnetic pole position output from the position detection means, and PWM control means for converting the voltage waveform into the PWM signal, and the number of regenerative detections of the regenerative voltage detection means, A conduction angle control means for controlling a conduction angle of a voltage waveform of the voltage control means based on a physical quantity related to a direct current is provided. Motor control apparatus. The motor control device according to claim 1, wherein the energization angle control means reduces the energization angle when the direct current change rate is large, and increases the energization angle when the direct current change rate is small. The motor control apparatus according to claim 2, wherein the conduction angle control means is a linear function expression of a direct current change rate. The motor control device according to claim 1, wherein the energization angle control means reduces the energization angle when the DC current ripple rate is large, and increases the energization angle when the DC current ripple rate is small. The motor control apparatus according to claim 4, wherein the conduction angle control means is a linear function expression of a direct current ripple rate. The motor control device according to claim 1, wherein the energization angle control means reduces the energization angle when the DC current average value is large, and increases the energization angle when the DC current average value is small. The motor control device according to claim 6, wherein the conduction angle control means is a linear function expression of a direct current average value. The motor control device according to claim 3, wherein the linear function equation has an upper limit value and a lower limit value.

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