JP2012191731A - Control device of motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for controlling a motor under PWM control by accurately performing position detection of a rotator when a voltage of a terminal connected to a coil exceeds a reference voltage.SOLUTION: The control device is caused to function as: means that generates a reference position from a last position detection result; means that estimates a next position detection time from this reference position and a rotational speed of the motor; means that calculates a phase difference between the next position detection estimation time and an ON set position of a PWM control signal; means that determines whether or not the next position detection estimation time is present at the set position of the PWM control signal; and means that changes a cycle of any one carrier in order to displace the phase by the phase difference so that the position detection estimation time is to be at the center of the PWM control signal if the next position detection estimation time is not present at the center of the ON period of the PWM control signal.

Description

  The present invention relates to a sensorless DC motor control device using PWM (Pulse Width Modulation) control, which improves the stability of rotor position detection and prevents or reduces turbulence, noise, vibration, etc. caused by position detection errors. This relates to the control device.

FIG. 4 is a circuit diagram showing a sensorless DC motor drive circuit based on PWM control.
In FIG. 4, the motor 1 is connected to an inverter 2 that generates a PWM drive signal, and the inverter 2 is connected to a PWM signal generator 9 that outputs a PWM control signal.
The PWM control signal generator 9 is connected to a control device 4 that outputs a carrier signal for generating a PWM control signal and an output voltage command signal. The control device 4 is used to obtain a position detection signal of the motor 1. The outputs of the comparators 5U, 5V, and 5W for comparing the voltages Uv, Vv, and Wv of the U-phase terminal 7U, V-phase terminal 7V, and W-phase terminal 7W of the motor 1 with the reference voltage B are connected. The positive side is connected.

  In the inverter 2, as shown in FIG. 5, a pair of switching elements 6Up and 6Un, 6Vp and 6Vn, 6Wp and 6Wn are connected between the positive side and the negative side of the DC power source 3, respectively. , 6Un, 6Vp, 6Vn, 6Wp, 6Wn are connected to the corresponding outputs of the PWM signal generator 9.

The connection point of the switching elements 6Up and 6Un constituting the inverter 2 is connected to the U-phase terminal 7U of the motor 1, the connection point of the switching elements 6Vp and 6Vn is connected to the V-phase terminal 7V of the motor 1, and the connection point of the switching elements 6Wp and 6Wn. Is connected to the W-phase terminal 7W of the motor 1.
The switching elements 6Up, 6Un, 6Vp, 6Vn, 6Wp, and 6Wn are generic names including bipolar transistors, FETs, MOS-FETs, thyristors, insulated gate bipolar transistors, and the like, which are appropriate depending on the output and specifications of the motor. Selected.

In the configuration as described above, the voltages Vu, Vv, and Vw of the U-phase terminal 7U, V-phase terminal 7V, and W-phase terminal 7W of the motor 1 are compared with the reference voltage B by the comparators 5U, 5V, and 5W. The position information of the rotor is input to the control device 4.
The control device 4 generates a PWM control signal as shown in FIG. 7 on the basis of the position information from the comparators 5U, 5V, and 5W, for example, a carrier signal and a voltage command having an appropriate period C composed of a triangular wave. The signal is output to the PWM signal generator 9.

  The PWM signal generator 9 compares the voltage command signal Vc for each phase that determines the duty ratio of the PWM drive signal that controls the rotation of the motor 1 with the carrier signal, and rises when the carrier signal becomes equal to or higher than the voltage command signal Vc. A rectangular PWM control signal as shown in FIG. 7, which falls when the voltage command signal Vc becomes lower, is output to the inverter 2.

  The inverter 2 controls the switching elements 6Up, 6Un, 6Vp, 6Vn, 6Wp, and 6Wn on / off according to the PWM control signal from the PWM signal generator 9, and the U-phase terminal 7U, V-phase terminal 7V, A PWM drive signal is output to the W-phase terminal 7W to rotate the motor 1.

Hereinafter, rotation control of the motor 1 will be described.
A PWM control signal is given to the gate of the switching element 6Up from the control device 4 via the PWM signal generator 9 in the period of electrical angle 0 to 120 degrees shown in FIG. As shown in FIG. 8B, a PWM control signal is given during a period of 120 to 240 electrical angles, and the electrical angle of 240 to 240 is applied to the gate of the switching element 6Wp as shown in FIG. 8C. A PWM control signal is given during a period of 360 degrees.

  As shown in FIG. 8 (d), a PWM control signal is given to the gate of the switching element 6Un during a period delayed by an electrical angle of 180 degrees of the switching element 6Up, and the gate of the switching element 6Vn is shown in FIG. 8 (e). As shown in FIG. 8, a PWM control signal is given in a period delayed by an electrical angle of 180 degrees of the switching element 6Vp, and the electrical angle of the switching element 6Wp is 180 degrees as shown in FIG. The PWM control signal is given during the delay period.

In the 120-degree energization method by PWM control, the PWM control signals given to the above switching elements 6Up, 6Un, 6Vp, 6Vn, 6Wp, and 6Wn have an initial electrical angle of 0 to 30 degrees and an end electrical angle of 90 to 120 degrees. A comb-like waveform in which the period repeats on and off, and a period with an intermediate electrical angle of 30 to 90 degrees is a flat plus waveform, and one of a pair of switching elements constituting a closed circuit described below is The comb-like waveform is controlled so that the other becomes a flat plus waveform.
The applied voltage is controlled by changing the duty ratio of the comb-like waveform to control the rotation speed to a desired value.

In the period of electrical angle 0 to 60 degrees, the switching elements 6Up and 6Vn become conductive and the positive side of the power source 3 → the switching element 6Up → the U phase coil 8U → the V phase coil 8V → the switching element 6Vn → the negative side of the power source 3 A closed circuit is formed and current flows.
Similarly, the switching elements 6Up and 6Wn are electrically connected in the period of 60 to 120 electrical angles, and in the direction from the U-phase coil 8U to the W-phase coil 8W, in the period of 120 to 180 electrical angles, 6Vp and 6Wn are conducted and the switching elements 6Vp and 6Un are conducted in the direction from the V-phase coil 8V to the W-phase coil 8W in the direction of the electrical angle of 180 to 240 degrees and the V-phase coil 8V to the U-phase coil 8U. In the direction of the electrical angle of 240 to 300 degrees, the switching elements 6Wp and 6Un are conducted, and in the direction of the W-phase coil 8W to the U-phase coil 8U, in the period of the electrical angle of 300 to 360 degrees, the switching element 6Wp. And 6Vn are conducted, and current flows in the direction from the W-phase coil 8W to the V-phase coil 8V.
As a result, a rotating magnetic field is generated by the coils 8U, 8V, and 8W to induce the rotor, and the motor rotates in a predetermined direction.

The rotor position detection will be described below.
A sensorless DC motor with PWM drive control using a 120-degree energization method has an induced voltage as shown in FIG. 6 applied to a stator coil to which any drive signal is not applied among U-phase, V-phase, and W-phase stator coils. V appears. The induced voltage V is compared with the reference voltage B to detect a point (points E and F in FIG. 6) that coincides with the reference voltage B, thereby detecting the position of the rotor. Based on this position information, the PWM drive signal is detected. And the motor is controlled to a desired rotational speed (Patent Document 1).

Hereinafter, the waveform of the voltage Vu appearing at the U-phase terminal 7U will be described with reference to FIG.
In the U-phase terminal 7U, an induced voltage Vu appears in a period of 120 to 180 electrical angles in which no voltage is applied and in a period of 300 to 360 degrees, but a series circuit of a V-phase coil 8V and a W-phase coil 8W. Since a voltage is applied to the three coils, a comb-like voltage is applied to the neutral point 10 of the three coils. As a result, the U-phase terminal 7U also has a comb-teeth waveform as shown in FIG. appear.
Similarly, a comb-tooth waveform that changes as shown in FIG. 8H appears in the V-phase terminal 7V in the period of electrical angle 60 to 120 degrees and the period of electrical angle 240 to 300 degrees, and in the W-phase terminal 7W. A comb-tooth waveform that changes as shown in FIG. 8 (i) appears in a period of 0 to 60 degrees electrical angle and a period of 180 to 240 degrees electrical angle.

Next, rotor position detection will be described by taking the U-phase terminal 7U as an example.
The rotor position can be detected by the induced voltage Vu appearing in the U-phase coil 8U when no driving voltage is applied to the U-phase terminal 7U. In the case of PWM control, the U-phase terminal is detected as described above. A comb-like voltage influenced by the PWM drive signal appears in the 7U voltage Vu.
The voltage Vu of the U-phase terminal 7U in which the comb-like voltage appears is compared with the reference voltage B. For example, the voltage Vu of the U-phase terminal 7U that appears in the period of the electrical angle 330 to 360 degrees in FIG. Is detected as the position of the rotor. As the reference voltage B, for example, a voltage obtained by dividing the voltage of the power source 3 by 1/2 using a resistor is used.

FIGS. 9A and 9B are partial enlarged views of the voltage Vu of the U-phase terminal 7U in the period of electrical angle 330 to 360 degrees.
The voltage Vu appearing at the U-phase terminal 7U has a comb-like voltage waveform that gradually increases.
In order to detect the position of the rotor using this, the voltage Vu appearing at the U-phase terminal 7U is compared with the reference voltage B by the comparator 5U, and the voltage Vu appearing at the U-phase terminal 7U matches the reference voltage B. Detect the point.
Further, the voltage Vu appearing at the U-phase terminal 7U has a voltage opposite in polarity to that at 330 to 360 degrees in the period of 150 to 180 degrees, and the voltage Vu and the reference voltage B are compared with the comparator 5U. And the point where the voltage Vu appearing at the U-phase terminal 7U matches the reference voltage B is detected.
Also for the V-phase terminal 7V and the W-phase terminal 7W, the same voltage is generated by shifting 120 degrees in electrical angle, position detection is performed in the same way, and position detection is performed 6 times during the electrical angle of 360 degrees. Done.

JP 59-139883 A.

  In the sensorless DC motor of the above PWM drive control, as shown in FIGS. 8G, 8H, and 8I, a comb-like waveform affected by the PWM drive signal is also applied to a terminal to which no voltage is applied. As shown in FIG. 9A, when the comb-like voltage Vu of the U-phase terminal 7U coincides with the reference voltage B during the period when it appears in the U-phase coil 8U, the position detection signal is correctly obtained. be able to.

However, during the period when the comb-like voltage Vu of the U-phase terminal 7U does not appear due to the influence of the PWM drive signal, the induced voltage Vu of the U-phase coil 8U indicated by the broken line in FIG. , The voltage Vu at the U-phase terminal 7U is 0, and that point cannot be detected.
In this case, since the voltage Vu of the U-phase terminal 7U exceeds the reference voltage B at the next rise timing when the PWM control signal is turned on, the comparator outputs a detection signal when the voltage exceeds the reference voltage B.
For this reason, when the point where the voltage Vu of the U-phase terminal 7U exceeds the reference voltage B is a period in which the voltage does not appear due to the influence of the PWM drive signal, an error occurs in the rotor position detection, resulting in turbulence, noise, There was a problem of causing vibration and the like.

  The present invention has been made in view of the above-described problems. Even when the point where the voltage Vu of each phase terminal of the motor stator exceeds the reference voltage B corresponds to the OFF period of the PWM control signal, It is an object of the present invention to provide a motor control device capable of detecting the position of a rotor with reduced error by predicting that point and preventing or reducing turbulence, noise, and vibration.

  Claim 1 of the present invention has a rotor and a stator composed of a plurality of phase coils, and sequentially applies a control voltage by PWM control to the stator to perform rotation control, and no control voltage is applied. A time when the voltage induced in the coil in the non-energized phase and the reference voltage coincide with each other is set as the rotor position detection time, and the position detection time of the rotor is fed back to the control device to perform the rotation control. In the DC motor control device, the control device includes means for estimating a next position detection time from the previous position detection time and the number of rotations of the motor, the next position detection estimated time, and a setting position where the PWM control signal is turned on. Means for calculating a phase difference between the first position and a position before the next position detection time estimated to shift the phase by the phase difference so that the next position detection estimated time is set to the ON position of the PWM control signal. A motor control device is characterized in that so as to function as a means for changing the period of A.

  Claim 2 of the present invention has a rotor and a stator composed of a plurality of phase coils, and sequentially applies a control voltage by PWM control to the stator to perform rotation control, and no control voltage is applied. A time when the voltage induced in the coil in the non-energized phase and the reference voltage coincide with each other is set as the rotor position detection time, and the position detection time of the rotor is fed back to the control device to perform the rotation control. In the DC motor control device, when the position of the rotor is detected, reference time detection means for acquiring the leading time of the PWM control carrier signal at the position detection time, the detection result of the reference time detection means, and Based on the position detection time, position detection time calculation means for calculating the time from the start of the PWM control carrier signal to position detection, and two positions based on the number of rotations and the number of poles of the motor Based on the detection results of the theoretical interval time calculating means for calculating the time between departure times and the reference time detecting means, the position detection time calculating means and the theoretical interval time calculating means, the latest position detection in the future from the reference time The next position detection estimated time calculating means for calculating the time until the next position detection estimated time calculating means, the next position detection estimated time calculating means, and the most recent position in the future based on the motor control command voltage and the frequency of the PWM control carrier signal. A determination unit that determines whether or not a next position detection estimation time that is a detection estimation time arrives in an ON section of the PWM signal, and when the next position detection estimation time and the PWM signal on section do not arrive by the determination unit, A means for calculating a phase difference between the next position detection estimated time and the center of the carrier waveform of PWM control, and a part of the carrier signal based on the phase difference A motor control device is characterized in that so as to function as a means for changing the period.

  Claim 3 of the present invention has a rotor and a stator composed of a plurality of phase coils, and sequentially applies a control voltage by PWM control to the stator to perform rotation control, and no control voltage is applied. A time when the voltage induced in the coil in the non-energized phase and the reference voltage coincide with each other is set as the rotor position detection time, and the position detection time of the rotor is fed back to the control device to perform the rotation control. In the DC motor control device, when the rotor position is detected, the motor control device acquires a leading time of a carrier signal of PWM control at the position detection time, and the reference time Based on the detection result of the detection means and the position detection time, the position detection time calculation means for calculating the time from the start of the carrier signal of PWM control to the position detection, the rotational speed of the motor, A theoretical interval time calculating means for calculating a time between two position detection times based on the number; and the reference time based on detection results of the reference time detecting means, the position detection time calculating means and the theoretical interval time calculating means. To the next position detection estimated time calculating means for calculating the time from the current position detection to the most recent position detection in the future, the calculation result by the next position detection estimated time calculating means, the frequency of the motor control command voltage and the PWM control carrier signal. Based on this, it is determined whether the next position detection estimated time, which is the latest position detection estimated time in the future, arrives in front of the center of the ON section of the PWM signal, arrives at the rear side, or arrives at the center of the ON section When the next position detection estimated time and the PWM signal ON section are not reached by the determining means and the determining means, Means for calculating a phase difference from the center of the waveform, means for changing the calculation method of the phase difference according to the result of the determination means, and means for changing a period of a part of the carrier signal based on the phase difference It is a motor control apparatus characterized by being made to function as.

  According to a fourth aspect of the present invention, in the motor control device according to the third aspect, the means for changing the phase difference calculation method is such that the next position detection estimated time comes before the center of the on-section of the PWM signal. , Phase difference = (carrier cycle C / 2) −surplus time S. When the next position detection estimated time arrives behind the center of the ON section of the PWM signal, phase difference = surplus time S− ( It is calculated by the carrier cycle C / 2) and is not calculated when the next position detection estimated time arrives at the center of the ON section of the PWM signal.

  According to the first and second aspects of the present invention, by changing the carrier cycle so that the next position detection estimated time becomes the ON setting position of the PWM control signal, the PWM control signal is always correctly set at the ON setting position. Since the position of the rotor can be detected, there is no error in detecting the position of the rotor, and it is possible to prevent or reduce turbulence, noise, vibration, and the like.

  According to the third and fourth aspects of the invention, since the means for changing the calculation method of the phase difference according to the result of the determination means is provided, the calculation of the phase difference is simplified and the calculation of the phase difference is not necessary. Since the calculation is not performed in some cases, the load on the control device can be reduced.

FIG. 4 is a waveform diagram of a carrier and a PWM control signal when an estimated next position detection time belongs to the second half of a triangular wave, for explaining the method according to the present invention, (a) is a waveform diagram before processing, and (b) is processing waveform. It is a later waveform diagram. FIG. 4 is a waveform diagram of a carrier and a PWM control signal when an estimated next position detection time belongs to the first half of a triangular wave for explaining the method according to the present invention, (a) is a waveform diagram before processing, and (b) is a processing diagram. It is a later waveform diagram. It is a flowchart which shows the process of moving the position of the PWM control signal of this invention, and is a main flowchart. It is a flowchart which shows the process of moving the position of the PWM control signal of this invention, and is a flowchart of the calculation process of theoretical area time. It is a flowchart which shows the process of moving the position of the PWM control signal of this invention, and is a flowchart of the calculation process of the number of carriers and a surplus time until the next position detection. It is a flowchart which shows the process of moving the position of the PWM control signal of this invention, and is a flowchart of a parameter setting process in case surplus time> carrier period / 2. It is a flowchart which shows the process of moving the position of the PWM control signal of this invention, and is a flowchart of a parameter setting process in the case of surplus time <carrier period / 2. It is a flowchart which shows the process of moving the position of the PWM control signal of this invention, and is a flowchart of a parameter setting process in case surplus time = carrier period / 2. It is a circuit diagram which shows the control circuit of the sensorless DC motor by PWM control. It is a circuit diagram which shows the detail of an inverter. In the conventional position detection of a rotor, it is a figure which shows the relationship between the position of a rotor, and an induced voltage. It is a wave form diagram which shows the carrier waveform output from the control apparatus 4 to the PWM signal generator 9. FIG. It is a wave form diagram which shows the voltage which appears in the terminal of a PWM control signal and each phase, (a) is a drive signal of switching element 6Up, (b) is a drive signal of switching element 6Vp, (c) is a drive signal of switching element 6Wp. , (D) is a drive signal for the switching element 6Un, (e) is a drive signal for the switching element 6Vn, (f) is a drive signal for the switching element 6Wn, (g) is a U-phase voltage Vu, and (h) is a V-phase. Voltages Vv and (i) are waveform diagrams of the W-phase voltage Vw. FIG. 7 is an enlarged view of a voltage waveform appearing at a terminal during a period in which the rotor position is detected by a conventional method, where (a) is a waveform diagram when position detection is normal, and (b) is a waveform diagram when position detection is abnormal. is there.

As described above, a comb-like voltage appears at the terminals of each phase, and an accurate detection signal can be obtained when the reference voltage B is exceeded during the ON period of the PWM control signal. During the OFF period, the point at which the voltage appearing at the terminal exceeds the reference voltage B cannot be detected accurately.
In the present invention, when it is estimated that a position to be detected comes in the off period of the PWM control signal, the position of the rotor is correctly detected by moving the on period of the PWM control signal. Movement of the PWM control signal during the ON period is performed by changing the carrier period before the estimated next position detection time.

Next, examples of the present invention will be described.
The circuit of the motor control device of the present invention has a basic configuration common to that of the conventional example shown in FIG. 4, and description of portions common to this conventional example is omitted.
The motor control device of the present invention is different from the conventional circuit configuration in that the control device 4 includes a means for generating a reference position from the previous position detection result, and the next position detection time from the reference position and the motor rotation speed. , Means for calculating the phase difference between the next position detection estimated time and the PWM control signal ON set position, and whether the next position detection estimated time is at the PWM control signal ON set position. If the next position detection estimated time is not at the set position where the PWM control signal is on, the phase difference is set by the phase difference so that the next position detection estimated time is at the center of the PWM control signal on. In order to shift, it is made to function as a means to change the period of one arbitrary carrier before the next position detection estimated time.

Hereinafter, as an embodiment of the present invention, a step of changing the carrier cycle is described with reference to FIGS. 1 (a) and 1 (b), FIGS. 2 (a) and 2 (b), and FIGS. 3 (a) to 3 (f). Will be described in detail as an example.
Steps (S0) to (S6) are common regardless of where the estimated next position detection time belongs in the triangular wave. S represents a step, and the subsequent number represents a step number.

(S0) The processing for changing the carrier cycle is started when the control device 4 receives an input of the position detection signal from the comparator 5U.
(S1) The position detection time Ti1, which is the time when the control device 4 receives the position detection signal from the comparator 5U, is acquired.
(S2) The control device 4 acquires the leading time (hereinafter referred to as reference time) Ti0 of the carrier in the carrier signal at the input time of the position detection signal, and the position detection time t1 from the reference time Ti0 and the position detection time Ti1. Is calculated.
(S3) The control device 4 calculates a theoretical interval time t2, which is a time interval until the next position detection estimated from the latest position detection is performed.

The calculation of the theoretical interval time t2 is as shown in FIG.
(S31) Theoretical frequency = (number of revolutions × (number of poles / 2)) is calculated from the number of rotations of the motor calculated based on the time interval of the position detection signal input from the comparator 5U and the number of stations of the motor.
(S32) Theoretical electrical angle period = (1 / theoretical frequency) is further calculated from the theoretical frequency.
(S33) Theoretical interval time t2 = theoretical electrical angle period × (60/360) is calculated.

(S4) When the theoretical interval time t2 is calculated in the control device 4, the next position detection position estimation time t3 = t1 + theoretical interval time t2 from the position detection time t1 and the theoretical interval time t2 calculated so far. Is calculated.
(S5) When the next position detection estimated time t3 is calculated, the control device 4 next calculates the number of carriers from the reference time Ti0 to the next position detection estimated time Ti3 and the surplus time S described later.

The calculation of the surplus time S is as shown in FIG.
(S51) Since the period C of the carrier signal for generating the PWM signal is constant, the number of carriers N = next position detection estimated time t3 / carrier period C is calculated. The number of carriers N calculated here takes an integer value excluding the remainder.
(S52) The surplus period S = next position detection estimated time t3- (carrier cycle C × number of carriers N) is calculated. The surplus time corresponds to the remainder of the calculation result of the number of carriers N in step S51.

(S6) When the surplus time S is calculated, the control device 4 next compares the surplus time S with the carrier period C / 2. Based on the comparison result, any one of the following three parameter processes (S7, S8, S9) is performed.
(S7) If the surplus time S is greater than the carrier period C / 2 by comparison in step S6, in other words, if the next position detection predicted time Ti3 is behind the top of the carrier as shown in FIG. The following processing shown in 3 (d) is performed.
(S71) When the surplus time S is larger than the carrier cycle C / 2, the phase difference D is calculated by subtracting the carrier cycle C / 2 from the surplus time S.
(S72) The changed carrier cycle C ′ = (carrier cycle C + (surplus time S−carrier cycle C / 2)) is calculated.
(S73) The next carrier change flag is set to TRUE, that is, the next carrier change execution flag is set.

(S8) If the surplus time S is smaller than the carrier period C / 2 by the comparison in step S6, in other words, as shown in FIG. 2A, the next position detection predicted time Ti3 is before the top of the carrier. The following processing shown in 3 (e) is performed.
(S81) When the surplus time S is smaller than the carrier period C / 2, the phase difference D is calculated by subtracting the surplus time S from the carrier period / 2.
(S82) The changed carrier cycle C ′ = (carrier cycle C− (surplus time S−carrier cycle C / 2)) is calculated.
(S83) The next carrier change flag is set to TRUE, that is, the next carrier change execution flag is set.

(S9) If the surplus time S is equal to the carrier cycle C / 2 by comparison in step S6, in other words, if the next position detection predicted time Ti3 is at the top of the carrier, the following processing shown in FIG. It is.
(S91) The next carrier cycle change flag is set to FALSE, that is, the next carrier cycle change execution flag is not set.

(S10) When the parameters are set in S7 to S9, the control device 4 determines the next carrier change flag, executes the following processing in the case of TRUE based on the determination result, and performs the following processing in the case of FALSE. The process ends without processing (S13).
(S11) In the parameter setting, when the carrier change flag is “TRUE”, the control device 4 uses the changed carrier period C ′ as shown in FIG. 1 (b) or FIG. 2 (b). The period of one carrier is changed for the carrier next to the carrier at the most recent position detection time.
(S12) The next carrier change flag is set to “FALSE”.
(S13) The carrier cycle changing process by the control device 4 is terminated.
Then, the PWM control signal ON period is formed by the carrier whose period has been changed, and the next position detection time Ti3 estimated at the center of the PWM control signal ON period arrives and correct position detection is performed.

The carrier period changing process described above is performed in a period of 150 to 180 degrees in the electrical angle of the U phase, a period of 330 to 360 degrees in the electrical angle, a period of 90 to 120 degrees in the electrical angle in the V phase, and 270 to 300 in the electrical angle. The above-described carrier cycle change process is performed six times during an electrical angle of 360 degrees by performing position detection based on the induced voltage of each phase of the W phase, 30 to 60 degrees of the W phase, and 210 to 240 degrees. Is done.
As a result, the sensorless DC motor is driven and controlled according to the six position signals correctly or with reduced errors, thereby preventing or reducing turbulence, noise, and vibration.

  In the above embodiment, the carrier period is reduced when the estimated next position detection time Ti3 is in the first half of the carrier, and is increased when it is in the second half, but the present invention is limited to this. Instead of something, it may be always made smaller or always made larger. In this case, even if the estimated next position detection time Ti3 coincides with the center of the carrier, it can be processed by the same calculation in one flow, and the flow can be simplified, but the carrier cycle is always changed. Since processing is performed, the load on the control device 4 increases.

  DESCRIPTION OF SYMBOLS 1 ... Motor, 2 ... Inverter, 3 ... DC power supply, 4 ... Control device, 5U, 5V, 5W ... Comparator, 6Up, 6Un, 6Vp, 6Vn, 6Wp, 6Wn ... Switching element, 7U ... U-phase terminal, 7V ... V phase terminal, 7W ... W phase terminal, 8U ... U phase coil, 8U ... V phase coil, 8W ... W phase coil, 9 ... PWM signal generator.

Claims (4)

It has a rotor and a stator composed of coils of a plurality of phases, and controls rotation by sequentially applying a control voltage by PWM control to the stator, and is induced in a coil of a non-energized phase to which no control voltage is applied. In the control device for the sensorless DC motor for performing the rotation control by returning the rotor position detection time to the control device as a time at which the detected voltage and the reference voltage coincide with each other as a rotor position detection time,
The control device;
Means for estimating the next position detection time from the previous position detection time and the number of rotations of the motor;
Means for calculating a phase difference between the next position detection estimated time and the ON setting position of the PWM control signal;
It was made to function as a means for changing the carrier cycle before the next position detection time estimated to shift the phase by the phase difference so that the next position detection estimated time becomes the ON set position of the PWM control signal. A motor control device characterized by the above. It has a rotor and a stator composed of coils of a plurality of phases, and controls rotation by sequentially applying a control voltage by PWM control to the stator, and is induced in a coil of a non-energized phase to which no control voltage is applied. In the control device for the sensorless DC motor for performing the rotation control by returning the rotor position detection time to the control device as a time at which the detected voltage and the reference voltage coincide with each other as a rotor position detection time,
A reference time detecting means for acquiring a leading time of a carrier signal for PWM control at the position detection time when the position of the rotor is detected;
Position detection time calculating means for calculating the time from the beginning of the carrier signal of PWM control to position detection based on the detection result of the reference time detection means and the position detection time;
Theoretical interval time calculating means for calculating a time between two position detection times based on the number of rotations and the number of poles of the motor;
Based on the detection results of the reference time detection means, the position detection time calculation means, and the theoretical interval time calculation means, a next position detection estimated time calculation means that calculates a time from the reference time to the most recent position detection in the future;
The next position detection estimated time, which is the most recent position detection estimated time in the future, is calculated based on the calculation result of the next position detection estimated time calculating means and the frequency of the motor control command voltage and the PWM control carrier signal. A determination means for determining whether or not to arrive in the section;
Means for calculating a phase difference between the next position detection estimated time and the center of the PWM control carrier waveform when the next position detection estimated time does not arrive in the ON section of the PWM signal by the determination means;
A motor control apparatus characterized in that it functions as means for changing a part of the period of a carrier signal based on the phase difference.
Data controller. It has a rotor and a stator composed of coils of a plurality of phases, and controls rotation by sequentially applying a control voltage by PWM control to the stator, and is induced in a coil of a non-energized phase to which no control voltage is applied. In the control device for the sensorless DC motor for performing the rotation control by returning the rotor position detection time to the control device as a time at which the detected voltage and the reference voltage coincide with each other as a rotor position detection time,
The motor control device comprises:
A reference time detecting means for acquiring a leading time of a carrier signal for PWM control at the position detection time when the position of the rotor is detected;
Position detection time calculating means for calculating the time from the beginning of the carrier signal of PWM control to position detection based on the detection result of the reference time detection means and the position detection time;
Theoretical interval time calculating means for calculating a time between two position detection times based on the number of rotations and the number of poles of the motor;
Based on the detection results of the reference time detection means, the position detection time calculation means, and the theoretical interval time calculation means, a next position detection estimated time calculation means that calculates a time from the reference time to the most recent position detection in the future;
The next position detection estimated time, which is the most recent position detection estimated time in the future, is calculated based on the calculation result of the next position detection estimated time calculating means and the frequency of the motor control command voltage and the PWM control carrier signal. Means for determining whether to arrive at the front of the section center, at the back side, or at the center of the on section;
Means for calculating a phase difference between the next position detection estimated time and the center of the PWM control carrier waveform when the determination means does not arrive at the next position detection estimated time and the ON section of the PWM signal;
Means for changing the calculation method of the phase difference according to the result of the determination means;
A motor control apparatus characterized in that it functions as means for changing a part of the period of a carrier signal based on the phase difference.   The means for changing the calculation method of the phase difference is calculated by the phase difference = (carrier cycle C / 2) −the surplus time S when the next position detection estimated time arrives in front of the center of the ON section of the PWM signal. When the next position detection estimated time arrives behind the center of the ON section of the PWM signal, it is calculated by phase difference = surplus time S− (carrier cycle C / 2), and the next position detection estimated time is calculated from the PWM signal. 4. The motor control device according to claim 3, wherein the calculation is not performed when the vehicle arrives at the center of the ON section.

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