JP2005304133A - Motor driving method and motor driving unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve lower vibration and lower noise property by suppressing the efficiency deterioration or increase of torque ripple due to the dispersion of the sensor attachment position in a motor whose position is detected by a sensor, and reducing the abrupt change in drive current waveform. <P>SOLUTION: A sensor signal correcting circuit 11 calculates a correction position signal, based on the sensor phase information obtained by a one-phase sensor signal outputted from a positional sensor 1 and the counter electromotive voltage phase information obtained by the counter electromotive voltage to the above phase outputted from a counter electromotive voltage detecting circuit 9. An energization control circuit 2 decides an energization phase, based on the correction position signal calculated by the sensor signal correcting circuit 11. A PWM control circuit 7 generates a signal for driving a phase to be PWM-driven which is decided by the energization control circuit 2. When an output transistor 3 energizes the phase selected by the energization control circuit 2, motor winding 4 is also energized. A current detector 5 detects a current value, and when it reaches the target current value decided by a control commanding part 6, it switches off the energization to make it nonconductive thereby performing switching control. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a motor driving method and a motor driving device that perform rotor position detection using at least one position sensor.

  As a conventional motor PWM drive system, there is a peak current control type motor drive system in which energization is turned off when a current flowing through a motor winding is detected and a target current value is reached. In this method, since the current is directly controlled by turning off when the current value reaches the target value, there is no delay in the current phase.

  The driving method disclosed in Patent Document 1 will be described with reference to FIG.

  FIG. 5 is a block diagram of a conventional motor driving apparatus for driving a three-phase motor, where 1 is a position sensor, 2 is an energization control circuit, 3 is an output transistor, 4 is a motor winding, 5 is a current detector, 6 Is a control command unit, 7 is a PWM control circuit, and 8 is a power source.

  As the position sensor 1, a hall element or the like is used. The position sensor 1 is disposed every 120 degrees and detects the position of the rotor of the motor. The energization phase is determined by the energization control circuit 2 from the sensor signal output by the position sensor 1. Further, a signal for driving a phase to be PWM driven determined in the energization control circuit 2 is formed by the PWM control circuit 7.

When the output transistor 3 is energized for the phase selected by the energization control circuit 2, a current flows through the motor winding 4, the current is detected by the current detection unit 5, and the target current value determined by the control command unit 6 When reaching the value, switching control is performed by turning off the power and making it non-conductive. Therefore, the peak value of the current flowing through the motor winding 4 is controlled to be constant by the input signal.
Japanese Patent Laid-Open No. 11-18474

  However, in the prior art, drive control is performed by the energization control circuit 2 only by position information obtained using the position sensor 1 such as a Hall element. Therefore, when there is an error in the mounting position of at least one position sensor 1, accurate position detection becomes difficult, and a deviation occurs between the motor position and the drive signal. As a result, a reduction in torque and a ripple occur, resulting in a deterioration in efficiency.

  Similarly, when there are relative variations in the mounting positions of a plurality of sensors, unevenness of the current flowing through the motor winding also occurs between the phases, and torque ripple increases. Therefore, the rotational speed of the motor or the current consumption varies.

  An object of the present invention is to provide a motor driving method and a motor driving device that reduce unevenness in rotational speed or variation in current consumption.

  In order to achieve the above object, the present invention detects the rotor position using at least one sensor such as a Hall element, and stores the difference from the position sensor signal by capturing the rotor position signal from the back electromotive voltage. Then, the position sensor signal is corrected using the phase difference.

  According to the present invention, even in the case of a motor with a sensor mounting position error or variation, the rotor position is accurately detected, the timing deviation of the drive signal from the rotor position is reduced, efficiency is improved, and torque ripple is suppressed. , Low vibration can be achieved, and further noise reduction can be achieved by storing the deviation value and correcting the timing of the rotor position signal in a 180-degree energization state such as sine wave current drive Thus, a stable motor drive capable of suppressing variations in rotational speed or current consumption, torque ripple, and noise reduction can be realized.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a configuration diagram of a three-phase motor driving apparatus for explaining an embodiment of the present invention, wherein 1 is a position sensor, 2 is an energization control circuit, 3 is an output transistor, 4 is a motor winding, and 5 is a current. A detection unit, 6 is a control command unit, 7 is a PWM control circuit, 8 is a power source, 9 is a counter electromotive voltage detection circuit, 10 is a phase difference detection circuit, and 11 is a sensor signal correction circuit.

  The operation of the motor driving apparatus configured as described above will be described below.

  A Hall element or the like is used as the position sensor 1. The position sensor 1 is arranged every 120 degrees and detects the position of the rotor of the motor. The counter electromotive voltage generated by the rotation of the motor is detected by the counter electromotive voltage detection circuit 9.

  Here, the phase difference detection circuit 10 will be described with reference to FIG.

  2A is sensor phase information obtained from a one-phase sensor signal output from the position sensor 1, and FIG. 2B is obtained from a counter electromotive voltage for the phase output from the counter electromotive voltage detection circuit 9. FIG. The counter electromotive voltage phase information is shown.

  The phase difference detection circuit 10 calculates the relative time difference α between the sensor phase in FIG. 2A and the counter electromotive voltage phase in FIG. 2B and the time β in one cycle in the sensor phase in FIG. And the ratio of α and β is held as α / β = k.

  Next, the sensor signal correction circuit 11 will be described with reference to FIG.

  FIG. 3A shows sensor phase information obtained from a one-phase sensor signal output from the position sensor 1.

  The sensor signal correction circuit 11 detects the time γ of one cycle of FIG. 3A, calculates the time difference k × γ from the k calculated and held by the phase difference detection circuit 10, and the waveform of FIG. A waveform shifted by k × γ time, that is, FIG. 3B is created. Since the phase shift between the counter electromotive voltage and the position sensor signal is fixed, FIG. 3B is a position signal having the same phase as the counter electromotive voltage.

  Here, the phase difference detection circuit 10 and the sensor signal correction circuit 11 have been described as performing the phase correction operation for only one phase, but the phase correction operation may be performed for each of the three phases.

  In the circuit configuration that generates a three-phase drive signal using one phase of the position sensor signal, the difference from the back electromotive voltage signal phase is detected only from the one phase, and the position sensor phase information of the phase is corrected from this. In addition, two other phases whose phases are shifted by 120 degrees may be generated.

  In this embodiment, the purpose is to maintain efficiency. However, if the efficiency is not concerned, the back electromotive voltage detection circuit 9 is omitted, and the phase difference detection circuit 10 obtains the sensor phase obtained from the signal output from the position sensor 1. A method may be employed in which the phase of each phase of information is detected, the phase deviation is calculated and held, and position correction is performed by the sensor signal correction circuit 11.

  The position correction will be described with reference to FIG. Each phase of the sensor phase information is shown in FIGS. 4 (a), 4 (b), and 4 (c).

In the phase difference detection circuit 10, one cycle time ε of any one phase, the phase time difference η in FIGS. 4A and 4B, and the phase time difference in FIGS. 4B and 4C ζ and the phase time difference ξ in FIG. 4C and FIG. 4A are detected, the phase shift in FIG. 4A is calculated based on the following equation (Equation 1), and the ratio of ε and n is calculated. , Ε / n = m.
(Equation 1)
n = {− (ξ−120 degrees) + (η−120 degrees)} / 2 × {| η−120 degrees | / (| η−120 degrees | + | ζ−120 degrees |)}
Further, an arithmetic expression that can reduce the deviation with higher accuracy than the expression (Equation 1) may be used.

  Thereafter, the sensor signal correction circuit 11 corrects FIG. 4A for m × ε time, and forms the other two phases shifted by 120 degrees from the corrected signal.

  In this case, by eliminating the relative variation of the position sensor and reducing the significant deviation of the sensor position, it is possible to reduce the torque ripple and generate a three-phase drive current that is different in phase by 120 degrees accurately. Vibration can be achieved.

  An energization phase is determined by the energization control circuit 2 based on the corrected position signal output from the sensor signal correction circuit 11. Further, a signal for driving the phase to be PWM driven determined in the energization control circuit 2 is generated by the PWM control circuit 7. When the output transistor 3 is energized for the phase selected by the energization control circuit 2, the motor winding 4 is also energized. When the current value is detected by the current detection unit 5 and the target current value determined by the control command unit 6 is reached, switching control is performed by turning off the current and turning it off.

  In the present embodiment, PWM driving has been described for the purpose of low power consumption, but linear driving can also be applied when low power consumption is not an issue. The energization phase is determined by the energization control circuit 2 from the position information signal corrected by the sensor signal correction circuit 11 without the PWM control circuit 7. The amplitude of energization is determined by the voltage of the control command unit 6. If the position sensor is a Hall element, the energization waveform may be generated from the output of the Hall signal corrected by the sensor signal correction circuit 11, or a sensor such as a trapezoidal wave or a sine wave from the phase information by the sensor signal correction circuit 11. A signal waveform may be generated.

  Thus, in this embodiment, since the phase information of the position sensor signal is corrected by the phase information of the back electromotive voltage signal, correct rotor position detection can be performed even if there is an error or variation in the sensor mounting position. .

  Further, referring to the arrangement of the position sensor 1, the sensor signal is usually detected about 30 degrees ahead or 30 degrees behind the energization signal. When a position sensor advanced by 30 degrees is used, k = (α−30 degrees) / β, and a phase signal obtained by delaying the position sensor signal by 30 degrees + k × γ may be given to the energization control circuit 2. Such a method is not limited to the case where the phase difference between the position sensor arrangement and the energization signal is 30 degrees, and can achieve the desired effect.

  Further, in order to reduce noise due to torque ripple or a sharp change in current, it is preferable that the energization angle of the drive current waveform is close to 180 degrees. In the method of generating the drive signal from the back electromotive voltage detection signal, when the output transistor is made non-conductive and detected by the voltage difference between the output terminal of the output transistor and the motor middle point, the conduction angle is equal to the back electromotive voltage detection section. Decreases and the conduction angle becomes less than 180 degrees.

  However, in this embodiment, once the phase difference is detected, the value is held (stored), and the phase information of the position sensor signal corrected thereby is used. Therefore, vibration or noise can be sufficiently reduced. Further, if the control command unit 6 performs sinusoidal current drive, vibration or noise can be further reduced.

  Back electromotive force detection is performed at the timing when the motor rotates to some extent. If one cycle is detected at the rising timing, the phase difference is detected by the difference in falling timing located at the midpoint of that cycle. Or, it is better to improve the accuracy by a method such as averaging the phase differences before and after one cycle to be detected.

  In addition, if the position sensors are basically the same, the phase difference does not change. Therefore, a test sequence circuit may be provided to accumulate phase correction information only at the time of test or startup. Considering that the phase sensor signal fluctuates due to the change, the phase correction information may be accumulated once every several times.

  The present invention is useful for driving a motor that needs to reduce variations in rotational speed or current consumption.

The block diagram of the three-phase motor drive device for demonstrating embodiment of this invention Waveform diagram for explaining the operation of the phase difference detection circuit in the present embodiment Waveform diagram for explaining the operation of the sensor signal correction circuit in the present embodiment Waveform diagram for explaining the average correction operation of the phase deviation of each phase in the present embodiment Configuration diagram of a conventional motor drive device

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Position sensor 2 Current supply control circuit 3 Output transistor 4 Motor winding 5 Current detection part 6 Control command part 7 PWM control circuit 8 Power supply 9 Back electromotive voltage detection circuit 10 Phase difference detection circuit 11 Sensor signal correction circuit

Claims (5)

In a motor driving method for detecting the position of a rotor using at least one position sensor,
A motor that stores information related to a phase difference between a back electromotive voltage and an output signal of the position sensor, corrects the output signal of the position sensor based on the phase difference information, and generates an energization signal. Driving method. In a motor driving method for detecting the position of a rotor using a plurality of position sensors,
Capturing a counter electromotive voltage, storing information related to a phase difference between the counter electromotive voltage and an arbitrary one-phase sensor signal, correcting the sensor signal based on the phase difference information, and generating an energization signal A motor driving method characterized by the above. In a motor driving method for detecting the position of a rotor using a plurality of position sensors,
A predetermined correction value is calculated using a phase deviation between phases detected by the position sensor, the correction value is stored, an output signal of the position sensor is corrected based on the correction value, and an energization signal Generating a motor.   A position sensor that performs position detection; a sensor signal correction circuit that corrects a position sensor signal from the position sensor; and an energization control circuit that creates an energization signal from the corrected signal, and corrects the position sensor signal. A motor driving device that generates a driving voltage.   A position sensor that performs position detection, a counter electromotive voltage detection circuit that detects a counter electromotive voltage, a phase difference detection circuit that compares a phase difference between the counter electromotive voltage and a sensor signal from the position sensor, and the phase difference And a sensor signal correction circuit that generates an energization signal from the position sensor signal based on the position sensor signal, and generates a drive voltage by correcting the position sensor signal according to the timing of the back electromotive voltage. .

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