JP2006174665A - Motor controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor controller with the running performance improved. <P>SOLUTION: This motor controller is equipped with a DC-AC conversion means which converts DC voltage into AC voltage, based on a PWM signal, by a switching element and supplies it to a three-phase brushless DC motor; an induced voltage detecting means which detects the induced voltage of the brushless DC motor; a magnetic pole position detecting means which detects the magnetic pole position of the brushless DC motor from the induced voltage; a voltage control means which outputs a voltage waveform, based on the magnetic pole position outputted from the magnetic pole position detecting means; a PWM control means which converts the waveform of voltage into a PWM signal; and a regenerative voltage detecting means which detects the regenerative voltage contained in the induced voltage. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

  Conventional motor control devices that control the rotational speed of a brushless DC motor include a 120 ° energization control method (see, for example, Patent Document 1) and a sine wave 180 ° energization control (see, for example, Patent Documents 2 and 3).

  The 120 ° energization method is a method in which the above-mentioned patent directly detects 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 mechanical angle 30 °, that is, every electrical angle 60 °.

For the 180 ° energization method, the above patent 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 integrates it A position detection signal corresponding to the induced voltage is obtained by comparing the output signal of the integration circuit input to the 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 because the integration circuit is passed.
Japanese Patent No. 2642357 JP 7-245982 A Japanese Patent Laid-Open No. 7-337079

  However, the conventional configuration has the following problems.

  FIG. 6 is a control block diagram of a conventional motor control device. Since this 120 ° energization method compares the zero cross of the induced voltage portion, if the motor load sudden change or the power supply voltage sudden change occurs, the induced voltage zero cross signal will be hidden in the inverter output voltage region and detected. It may not be possible.

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

  FIG. 7A 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. 7B is a relationship diagram between the phase current waveform and the induced voltage waveform in the 180 ° energization control.

  Since the 180 ° energization method passes through the integration circuit, the zero-cross position of the induced voltage cannot be accurately grasped with an 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 phase 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 has been made to solve the above-mentioned problems, and the object of the present invention is to provide a 180 ° sine wave with a position sensor by applying a new method of induced voltage feedback control that does not require a mechanical electromagnetic pickup sensor. An object of the present invention is to provide a motor control device that achieves a high speed performance of the same level, further improves the step-out limit torque in any operating load region, and is inexpensive and highly reliable.

  In order to solve the above-described conventional problems, a motor control device according to the present invention includes a plurality of switching elements, converts a DC voltage into an AC voltage based on a PWM signal by opening and closing the switching elements, and supplies the DC voltage to a three-phase brushless DC motor. AC conversion means, induced voltage detection means for detecting the induced voltage of the brushless DC motor, magnetic pole position detection means for detecting the magnetic pole position of the brushless DC motor from the induced voltage, and output from the magnetic pole position detection means Regenerative voltage detection for detecting a regenerative voltage included in the induced voltage in a motor control device having voltage control means for outputting a voltage waveform based on a magnetic pole position and PWM control means for converting the voltage waveform into the PWM signal Magnetic pole position detecting means for determining the magnetic pole position based on the detected regenerative voltage and the induced voltage The regenerative voltage detecting means has a predetermined reference voltage and determines the regenerative voltage by comparing the reference voltage with the induced voltage, and the reference voltage is the (voltage value of DC voltage) × (regenerative voltage) (Coefficient) or (voltage value of DC voltage) × (1−regenerative voltage coefficient), and the regenerative voltage coefficient is set based on a physical quantity related to the DC voltage.

  The motor control device of the present invention reduces the regenerative voltage coefficient when the DC voltage change rate is large, and increases the regenerative voltage coefficient when the DC voltage change rate is small.

  In the motor control device of the present invention, the regenerative voltage coefficient is a linear function expression of the DC voltage change rate.

  In the motor control device of the present invention, the linear function expression of the DC voltage change rate has an upper limit value and a lower limit value.

  The motor control device of the present invention increases the regenerative voltage coefficient when the DC voltage ripple ratio is large, and decreases the regenerative voltage coefficient when the DC voltage ripple ratio is small.

  In the motor control device of the present invention, the regenerative voltage coefficient is a linear function expression of a DC voltage ripple rate.

  In the motor control apparatus of the present invention, the linear function expression of the DC voltage ripple rate has an upper limit value and a lower limit value.

  According to the motor control device of the present invention, it is possible to provide a motor control device that avoids the step-out phenomenon caused by the regenerative voltage, and it is possible to construct an inverter system corresponding to a wide range of operation loads at low cost, and even when the DC voltage fluctuation is extremely large. Since it is possible to accurately determine the regenerative voltage and to prevent erroneous detection of the induced voltage, it is possible to provide a motor control device having high responsiveness, stability and reliability against voltage changes.

  According to a first aspect of the present invention, there is provided a DC / AC converter that includes a plurality of switching elements, converts a DC voltage into an AC voltage based on a PWM signal by opening and closing the switching elements, and supplies the AC voltage to a three-phase brushless DC motor, and induction of the brushless DC motor Induced voltage detecting means for detecting voltage, magnetic pole position detecting means for detecting the magnetic pole position of the brushless DC motor from the induced voltage, and voltage for outputting a voltage waveform based on the magnetic pole position output from the magnetic pole position detecting means In a motor control device having control means and PWM control means for converting the voltage waveform into the PWM signal, regenerative voltage detection means for detecting a regenerative voltage included in the induced voltage, the detected regenerative voltage and the Magnetic pole position detection means for determining the magnetic pole position based on the induced voltage, and the regenerative voltage detection means is a predetermined reference The regenerative voltage is determined by comparing the reference voltage with the induced voltage, and the reference voltage is the above (DC voltage value) × (regenerative voltage coefficient) or (DC voltage value) × (1 -Regenerative voltage coefficient), and the regenerative voltage coefficient is set based on a physical quantity related to the DC voltage.

  The second aspect of the invention is a motor control device in which the regenerative voltage coefficient of the first aspect of the invention is particularly small when the DC voltage change rate is large and large when the DC voltage change rate is small.

  The third aspect of the invention is a motor control device in which the regenerative voltage coefficient of the second aspect of the invention is a linear function expression of a DC voltage change rate.

  The fourth invention is a motor control device in which the linear function expression of the DC voltage change rate of the third invention has an upper limit value and a lower limit value.

  The fifth aspect of the present invention is a motor control device that particularly increases the regenerative voltage coefficient of the first aspect of the invention when the DC voltage ripple rate is large and decreases it when the DC voltage ripple rate is low.

  The sixth aspect of the invention is a motor control device in which the regenerative voltage coefficient of the fifth aspect of the invention is a linear function expression of a DC voltage ripple rate.

  The seventh aspect of the invention is a motor control device in which the linear function expression of the DC voltage ripple rate of the sixth aspect of the invention has an upper limit value and a lower limit value.

  Embodiments of a motor control device according to the present invention will be described below with reference to the accompanying drawings.

  Note that the present invention is not limited to the embodiments.

(Embodiment 1)
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 portion 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 device 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 converting means 6. .

  In the case of 120 ° energization control, the PWM control unit 5 outputs six types of PWM signals for opening and closing the switching elements of the DC / AC conversion unit 6, and the switching elements are opened and closed by the six types 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 detection means 2 will be described with reference to FIG. 2B, FIG. 3, and FIG.

  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 between 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 detection means 2 is as shown in FIG. 3B induced voltage 10a and FIG. 4B 10b 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 (the 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, the PWM signal for 120 ° energization control is used in the 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, the voltage waveform is defined as phase current 9.

  FIG. 8 is an equivalent circuit diagram of the BLM7.

  R1 is a winding primary resistance, Lu, Lv, and Lw are inductances of each phase, and Eu, Ev, and Ew are field-induced voltages 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,
True magnetic pole position ≡ induced voltage zero cross position.

That is, if the induced voltage 10 in FIG. 3A corresponds to the U phase, the zero cross U1≡the positive zero cross signal 11
Zero cross U2 = Reverse zero cross signal 12
It is.

In addition,
Eu ≠ induced voltage 10
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. 3, 4 and 5. FIG.

  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 incorrect, 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,
Induced voltage 10a ≧ VDC / 2
As one of the necessary conditions for determining the reverse zero cross signal 12,
Induced voltage 10b ≦ VDC / 2
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 regenerates 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 regeneration determination reference voltage 17 and a VTH2 regeneration determination reference voltage 18 inside, and makes a determination by comparing the values with the regenerative voltage 13 and the regenerative voltage 14.

Specifically, VTH 1 regeneration determination reference voltage 17 = (1−regenerative voltage coefficient) * VDC
VTH2 regeneration determination reference voltage 18 = regenerative voltage coefficient * VDC
It is. The regenerative voltage coefficient may be set appropriately.

  The regenerative voltage detecting 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 is acquired at time Tij31 intervals, and the regenerative voltage is determined for each V0j, V1j, V2j,.

Here, i and j are arbitrary natural numbers. When judging the regenerative voltage,
Vi = Σ (Vip) / (j + 1); p = 0 → j
And the regenerative voltage is determined by comparing Vi with VTH1 or VTH2.

That is, in the case of FIG.
Vi ≧ VTH1
In the case of FIG.
Vi ≦ VTH2
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 detecting means 2 obtains the positive zero cross signal 11 and the reverse zero cross signal 12 according to the conventional determination standard described above when the regeneration end signal is received.

  When the position determination is completed, the current cut is completed 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.

Controllability is improved by changing the regenerative voltage coefficient in accordance with the voltage change rate and ripple rate change of the VDC. If the voltage change rate is σ and the voltage ripple rate is ξ (≧ 0),
Regenerative voltage coefficient 1 = Kσ1 · σ + Kσ2
Or
Regenerative voltage coefficient 2 = Kξ1 ・ ξ + Kξ2
You can use mathematical expressions.

here,
Kσ1 <0
Kξ1, Kσ2, Kξ2> 0
Meet.

  In addition, an upper limit value and a lower limit value may be set for the regenerative voltage coefficient obtained from each of the above equations, and it is preferable to set the regenerative voltage coefficient within a real number that satisfies 0 <regenerative voltage coefficient <0.5.

If the maximum value of the DC voltage is VDCMAX, the minimum value is VDCMIN, and the average value is VDCAVE,
ξ = (VDCMMAX−VDCMMIN) / VDCAVE
The relationship is established.

  The meaning of the above regenerative voltage coefficient 1 is to reduce the regenerative voltage coefficient when the DC voltage change rate becomes a large positive number.

  In this case, since there is a delay in reading the DC voltage, a correction effect is produced in which the regeneration determination reference voltage VTH1 is increased with respect to the DC voltage increase after the DC voltage is detected.

  Even in the case where the DC voltage change rate is a negative number, a correction effect of reducing VTH1 with respect to the DC voltage decrease is produced.

  As a result, the response followability to the DC voltage is improved, the erroneous detection of the regenerative voltage is prevented, and the induced voltage can be accurately captured.

  On the other hand, the above expression regenerative voltage coefficient 2 means that the regenerative voltage coefficient is increased as the DC voltage ripple rate increases.

  In this case, since the DC voltage fluctuation value becomes large, a correction effect for reducing the regeneration determination reference voltage VTH1 in advance is produced with respect to the DC voltage decrease that occurs after the DC voltage is detected.

  When the DC voltage ripple ratio is small, the correction amount can be reduced.

  As a result, control stability against DC voltage fluctuation is improved, erroneous detection of the regenerative voltage is prevented, and the induced voltage can be accurately captured.

  As described above, the present invention has been described by taking a three-phase brushless DC motor as an example, but the concept is the same for application to a single-phase brushless DC motor, and departs from the gist, concept and claims of the present invention. It is possible to change, add, or delete the embodiment as appropriate within the range not to be performed.

Control block diagram of motor control apparatus of this embodiment (A) is a block diagram of DC / AC converting means (b) is a field induced voltage waveform relationship diagram of a three-phase brushless DC motor. Operation explanatory diagram of regenerative voltage detection means Operation explanatory diagram of regenerative voltage detection means Operation explanatory diagram of regenerative voltage detection 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 Regenerative voltage end point 30 Regeneration detection point 31 Regeneration detection time interval

Claims (7)

DC-AC conversion means that includes a plurality of switching elements, converts a DC voltage into an AC voltage based on a PWM signal by opening and closing the switching element, and supplies the AC voltage to a three-phase brushless DC motor; and an induced voltage for detecting the induced voltage of the brushless DC motor Detection means; magnetic pole position detection means for detecting the magnetic pole position of the brushless DC motor from 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; In a motor control device having a PWM control means for converting a waveform into the PWM signal, based on the regenerative voltage detection means for detecting a regenerative voltage included in the induced voltage, the detected regenerative voltage and the induced voltage. Magnetic pole position detecting means for determining the magnetic pole position, and the regenerative voltage detecting means has a predetermined reference voltage and the reference voltage. The regenerative voltage is determined by comparing the voltage with the induced voltage, and the reference voltage is the above (DC voltage value) x (regenerative voltage coefficient) or (DC voltage value) x (1-regenerative voltage coefficient). The motor control device characterized in that the calculated regenerative voltage coefficient is set based on a physical quantity related to the DC voltage. 2. The motor control device according to claim 1, wherein the regenerative voltage coefficient is decreased when the DC voltage change rate is large, and is increased when the DC voltage change rate is small. The motor control device according to claim 2, wherein the regenerative voltage coefficient is a linear function expression of a DC voltage change rate. 4. The motor control device according to claim 3, wherein the linear function expression of the DC voltage change rate has an upper limit value and a lower limit value. 2. The motor control device according to claim 1, wherein the regenerative voltage coefficient is increased when the DC voltage ripple rate is large and is decreased when the DC voltage ripple rate is small. 6. The motor control device according to claim 5, wherein the regenerative voltage coefficient is a linear function expression of a DC voltage ripple rate. The motor control apparatus according to claim 6, wherein the linear function expression of the DC voltage ripple rate has an upper limit value and a lower limit value.

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