JP2005261143A - Sensorless control method and apparatus of brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sensorless control method and apparatus of an analog brushless motor which can cope with sharp acceleration and deceleration. <P>SOLUTION: Integrator circuits 10u, 10v, 10w have an OP amplifier 13 and a capacitor circuit 14 connected in parallel. The integrator circuits 10u, 10v, 10w and comparison circuits 11u, 11v, 11w are used and generate analog rotational position estimating signals Hu, Hv, Hw from three phase voltages Vu, Vv, Vw. The brushless motor, using a permanent magnet, is controlled without a rotational position detecting sensor by controlling currents carried from a DC power supply to three phases, based on the rotational position estimating signals. The capacitance of the capacitor circuit 14 is switched, based on the rotational speed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a sensorless control method and apparatus for a brushless motor, and more particularly, a permanent magnet driven using a DC power source such as a brushless DC motor mounted on an automobile and used for driving a hydraulic pump. The present invention relates to a method and apparatus for controlling a used brushless motor without using a rotational position detection sensor such as a Hall element.

  Conventionally, DC motors with brushes have been used as electric motors mounted on automobiles to drive hydraulic pumps, steering devices, etc. However, there is a problem of reliability due to the durability of brushes, and brushless motors should be used. Is desired.

  As a typical brushless motor, a permanent magnet motor driven using a DC power source, such as a brushless DC motor, is known. In a conventional brushless DC motor, based on rotational position signals from three sensors. The rotor is rotationally driven by controlling energization to the three phases of the U phase, the V phase, and the W phase by the PWM method. The energization of each phase is normally performed by so-called 120-degree energization in which energization is performed only in a 120-degree section of an electrical angle of 180 degrees. Further, the rotational position signal of each phase is delayed by 30 degrees with respect to the induced voltage of that phase.

  As described above, three rotational position detection sensors are required for driving a conventional brushless DC motor. However, when the motor is mounted in a high-temperature engine room, there is a problem of heat resistance of the sensor. So-called sensorless driving for driving the motor without using the position detection sensor is required.

  As described in Non-Patent Document 1, sensorless driving of a brushless DC motor has already been put into practical use in home appliance motors. In order to sensorlessly drive a brushless DC motor, it is necessary to estimate the rotational position of the rotor and generate a rotational position estimation signal corresponding to the rotational position signal from the conventional rotational position detection sensor. Is generated using a three-phase induced voltage.

  There are an analog method and a digital method for generating the rotational position estimation signal.

  The analog system is composed of a 90-degree phase delay filter, a comparator (comparison circuit), and a logic circuit, and a rotational position estimation signal is obtained by shaping the terminal voltage of each phase by the filter and the comparator.

  In the case of digital sensorless driving, so-called one-side PWM driving is performed in which only one of the upper arm and lower arm of each phase is PWM driven. The digital system includes a comparator that compares a terminal voltage of each phase and a reference voltage, two high-speed counters that perform phase shift, and a logic circuit. When 120-degree energization is performed, the induced electromotive force of each phase is exposed in a section of 60 degrees outside the energization section of one cycle for each phase twice. In this section, the comparator compares the terminal voltage with the reference voltage to detect the zero-cross timing of the induced voltage, that is, the zero-cross point. A rotational position estimation signal corresponding to the rotational position signal from the rotational position detection sensor is obtained by performing a phase shift of 30 degrees using two types of counters.

  According to the digital system, the problem of the analog system to be described later is solved, but there is a problem that two kinds of high-speed counters are necessary and the circuit becomes complicated.

The analog system has advantages such as a simple circuit configuration and good compatibility with PWM control. However, since a 90-degree phase delay filter is used, there is a problem in that the rotation range is limited by its frequency characteristics, and it cannot cope with rapid acceleration / deceleration. In particular, when the load torque is large, step-out is likely to occur if the capacitance value of the capacitor constituting the 90-degree phase delay filter is small.
Published by Kazuo Nagatake “Motor Practical Pocketbook Motor / Inverter Technology for Home Appliances”, Nikkan Kogyo Shimbun, April 28, 2000

  An object of the present invention is to provide a sensorless control method and apparatus for an analog brushless motor that has a wide rotation range and can cope with sudden acceleration / deceleration.

  The sensorless control method for a brushless motor according to the present invention generates a rotational position estimation signal for each phase in an analog manner from the three-phase phase voltage using an integration circuit and a comparison circuit in which a capacitor circuit is connected in parallel to an OP amplifier. A method of controlling a brushless motor using a permanent magnet without using a rotational position detection sensor by controlling energization from a DC power supply to three phases based on a rotational position estimation signal of each phase, Based on this, the capacitance value of the capacitor circuit is switched.

  A sensorless control device for a brushless motor according to the present invention uses an integration circuit and a comparison circuit in which a capacitor circuit is connected in parallel to an OP amplifier to generate a rotational position estimation signal for each phase in an analog manner from three phase voltages. A position estimation signal generating means and an energization control means for controlling energization from the DC power supply to the three phases based on the rotational position estimation signal of each phase, and a brushless motor using a permanent magnet is used without using the rotational position detection sensor. The capacitor circuit includes a plurality of capacitors arranged in parallel and a switch connected in series to a predetermined capacitor, and the rotational position estimation signal generating means adjusts the rotational speed. Switching means for switching the capacitance value of the capacitor circuit by controlling on / off of the switch based on It is an feature.

  In the method and apparatus according to the present invention, the rotational position estimation signal is obtained by adding the advance angle in the advance angle control to the rotational position signal from the conventional rotational position sensor.

  An integration circuit and a comparison circuit are provided for each phase.

  The OP amplifier of the integration circuit receives the phase voltage and an intermediate voltage value of the phase voltage, the output of the OP amplifier is compared with a predetermined reference voltage value by the comparison circuit, and the output of the comparison circuit becomes the rotational position estimation signal.

  When the phase voltage exceeds the intermediate voltage value at the first zero cross point, the output of the OP amplifier increases linearly from the lower limit value, and eventually saturates to the upper limit value, and then the phase voltage reaches the intermediate voltage value at the second zero cross point. If it falls below, it decreases linearly from the upper limit value, eventually saturates to the lower limit value, and then increases again linearly at the first zero cross point. The increase rate and decrease rate of the output of the OP amplifier increase as the capacitance value of the capacitor circuit increases. The intermediate voltage value between the upper limit value and the lower limit value of the output of the OP amplifier is equal to the intermediate voltage value of the phase voltage.

  The reference voltage value input to the comparison circuit is equal to the intermediate voltage value of the phase voltage. The rotational position estimation signal, which is the output of the comparison circuit, is turned on when the output of the OP amplifier is larger than the reference voltage value, and is turned off otherwise.

  As a result, a rotational position estimation signal whose phase is delayed from the phase voltage is obtained. As described above, since the increase rate and decrease rate of the output of the OP amplifier increase as the capacitance value of the capacitor circuit increases, the phase delay angle of the rotational position estimation signal with respect to the phase voltage is the capacitance value of the capacitor circuit of the integration circuit. Becomes smaller as becomes larger. Therefore, the advance angle included in the rotational position estimation signal increases as the capacitance value of the filter capacitor circuit increases.

  When the rotation speed is the slowest, the capacitance value of the capacitor circuit is minimized, and the capacitance value of the capacitor circuit is increased as the rotation speed increases. Usually, when the capacitance value of the capacitor circuit is minimum, the advance angle is 0, and the phase delay angle of the rotational position estimation signal with respect to the phase voltage is 30 degrees, that is, the rotational position estimation signal is the conventional rotational position signal. To be the same.

  In this way, at low speed, the motor is driven based on a rotational position estimation signal with a leading angle of 0 or small, and at high speed, the leading angle control with a large leading angle is performed. For this reason, the motor can be driven in a wide range from low speed to high speed, and it is possible to cope with rapid acceleration / deceleration. Further, even if the load torque is large, there is no possibility of causing step-out.

  According to the method and apparatus of the present invention, the rotation range is wide, it can cope with sudden acceleration / deceleration, and there is no possibility of causing step-out.

  Hereinafter, an embodiment in which the present invention is applied to sensorless control of an in-vehicle brushless DC motor will be described with reference to the drawings.

  FIG. 1 shows an example of the configuration of a sensorless control device for a brushless DC motor.

  This sensorless control device drives a brushless DC motor (1) mounted on an automobile to drive a hydraulic pump or the like by using a direct current power source (2) comprising a battery mounted on the automobile. A rotational position estimation signal generator (3), which is a rotational position estimation signal generation means for generating a rotational position estimation signal for each phase in an analog manner based on the phase voltage, and a power source (2) based on the rotational position estimation signal for each phase ) To a three-phase energization control device (4) which is an energization control means for controlling energization. Let E be the DC voltage of the DC power supply (2). The three-phase voltages are Vu, Vv, and Vw, respectively, and are collectively referred to as V. The three-phase rotational position estimation signals are denoted by Hu, Hv, and Hw, respectively, and are collectively referred to as H.

  The energization control device (4) is the same as the conventional one, and includes a logic circuit (5), a gate drive circuit (6), and a switching circuit (7).

  The switching circuit (7) controls the energization of the upper arm switching element (8u +) and the lower arm switching element (8u-), which controls the U-phase energization from the power source (2) to the motor (1), and the V-phase. An upper arm switching element (8v +) and a lower arm switching element (8v-), and an upper arm switching element (8w +) and a lower arm switching element (8w-) for controlling energization to the W phase are provided. The switching elements are generically designated by reference numeral (8).

  As will be described later, the logic circuit (5) generates a switching element control signal Du + for each switching element (8) by a known method based on the rotational position estimation signal H generated by the rotational position estimation signal generator (3). , Du-, Dv +, Dv-, Dw +, Dw- are generated and output. The switching element control signal is generally referred to as D.

  The gate drive circuit (6) drives each element (8) on and off based on the switching element control signal D.

  The energization control device (4) controls the energization of each switching element by, for example, the PWM method.

  As shown in FIG. 2, the rotational position estimation signal generation device (3) includes a U-phase integration circuit (first integration circuit) (10u), a comparison circuit (first comparison circuit) (11u), and a V-phase integration circuit. Integration circuit (second integration circuit) (10v) and comparison circuit (second comparison circuit) (11v), W-phase integration circuit (third integration circuit) (10w) and comparison circuit (third comparison circuit) (11w) ), And a switching device (12) as switching means. The integration circuit is generally designated by reference numeral (10), and the comparison circuit is generally designated by reference numeral (11).

  The three-phase integration circuit (10) and the comparison circuit (11) are the same as each other.

  Each integrating circuit (10) is formed by connecting a capacitor circuit (14) in parallel to an OP amplifier (13).

  A corresponding phase voltage V and a predetermined reference voltage Yc are input to the OP amplifier (13), and outputs Yu, Yv, Yw of the corresponding integration circuit (10) and the above-described reference are input to the comparison circuit (11). The voltage Yc is input. The output of each comparison circuit (11) becomes the rotational position estimation signal H for each phase. The output of the integrating circuit (10) is collectively referred to as Y. The reference voltage Yc is a half value of the power supply voltage E, that is, an intermediate voltage value (= E / 2) of the phase voltage V.

  Each capacitor circuit (14) is provided between the phase voltage V, which is the input of the OP amplifier (13), and the output Y of the OP amplifier (13), and a plurality of capacitors (3 in this example) are connected in parallel. Capacitor), that is, first, second and third capacitors (15a), (15b) and (15c). Capacitors are generally designated by reference numeral (15). Switches (16b) and (16c) are connected in series to the second and third capacitors (15b) and (15c), respectively. For example, the capacitance value of each capacitor (15) is 1 μF for the first and second capacitors (15a) and (15b), and 3.3 μF for the third capacitor (15c). In this case, the capacitance value of the capacitor circuit (14) is 1 μF when the two switches (16b) and (16c) are both off (not connected), and only the second switch (16b) is on (connected). 2 μF, and when only the third switch (16c) is on, it becomes 4.3 μF, and when both the two switches (16b) and (16c) are both on, it becomes 5.3 μF.

  The switching device (12) controls on / off of the switches (16b) and (16c) of each integrating circuit (10) based on the detected rotational speed value of the rotor of the motor (1) detected by a rotational speed sensor (not shown). Thus, the capacitance value of the capacitor circuit (14) of each integrating circuit (10) is switched based on the rotation speed. More specifically, the entire rotation range of the motor (1) is divided into four ranges of first, second, third and fourth in order from the low speed side, and in the first area on the lowest speed side, two switches (16b) (16c) are both turned off. In the next second area, only the second switch (16b) is turned on. In the next third area, only the third switch (16c) is turned on. In the four regions, both the two switches (16b) and (16c) are turned on. By doing so, the capacitance value of the capacitor circuit (14) becomes 1 μF, 2 μF, 4.3 μF and 5.3 μF in the first, second, third and fourth regions, respectively, and the rotation speed is increased. The capacitance value of the capacitor circuit (14) is switched so as to increase.

  FIG. 3 is a time chart showing the relationship between the three-phase phase voltage V input to the OP amplifier (13) of the three-phase integration circuit (10) and the rotational position estimation signal H which is the output of the three-phase comparison circuit (11). It is a chart.

  As shown in FIG. 3, the phase voltage Vv of the V phase is 120 degrees behind the phase voltage Vu of the U phase, and the phase voltage Vw of the W phase is further 120 degrees with respect to the phase voltage Vv of the V phase. Running late. The rotational position estimation signal H is represented by 0 (off) and 1 (on), and the polarity is inverted every 180 degrees. Similarly to the phase voltage V, the V-phase rotational position estimation signal Hv is 120 degrees behind the U-phase rotational position estimation signal Hu, and the W-phase rotational position estimation signal Hw 120 degrees behind the rotational position estimation signal Hv. Further, the rotational position estimation signal H of each phase is delayed in phase by the electrical angle φ with respect to the phase voltage V. FIG. 3 shows a case where the rotation speed is in the first region and the capacitance value of the capacitor circuit 14 is minimum (1 μF in this example). In this case, φ is 30 degrees, that is, The integration circuit (10) is set so that the rotational position estimation signal H is the same as the conventional rotational position signal. When the capacitance value of the capacitor circuit (14) increases, the phase delay angle φ becomes smaller than 30 degrees as shown by the chain line in FIG. 3, and the lead angle control is performed.

  Next, generation of the U-phase rotational position estimation signal Hu in the rotational position estimation signal generation device (3) will be described in more detail with reference to FIG.

  FIG. 4 shows the relationship among the U-phase phase voltage Vu, the output Yu of the integrating circuit (10u), and the rotational position estimating signal Hu that is the output of the comparison circuit (11u) in the rotational position estimation signal generating device (3). . In FIG. 3, the solid line represents the case where the capacitance value of the capacitor circuit (14u) is minimum, and the chain line represents the case where the capacitance value is large.

  As shown in FIG. 4, the output Yu of the integrating circuit (10u) is linear from the lower limit value Ymin at the zero cross point from the negative to positive phase voltage Vu (first zero cross point = time of 0 ° in FIG. 4). After reaching the upper limit value Ymax and saturating, the phase voltage Vu decreases linearly from the upper limit value Ymax at the zero cross point (second zero cross point = 180 ° in FIG. 4) from positive to negative. Then, after eventually reaching the lower limit Ymin and saturating, it again increases linearly from the lower limit Ymin at the first zero cross point.

  In the comparison circuit (11u), the output Yu of the integration circuit (10u) is compared with the reference voltage Yc, and the rotational position estimation signal Hu that is the output of the comparison circuit (11u) is turned on when the output Yu is larger than the reference voltage Yc. ("1"), otherwise it is off ("0"). As a result, a rotational position estimation signal Hu having a phase delayed by an electrical angle φ with respect to the phase voltage Vu is obtained.

  As indicated by a chain line in FIG. 4, the increase rate and decrease rate of the output Yu of the integration circuit (10u) increase as the capacitance value of the capacitor circuit (14) increases. Therefore, the phase delay angle φ of the rotational position estimation signal Hu with respect to the phase voltage Vu decreases as the capacitance value of the capacitor circuit (14) increases. Therefore, the advance angle included in the rotational position estimation signal Hu increases as the capacitance value of the capacitor circuit of the filter increases.

  In the above rotational position estimation signal generation device (3), when the rotational speed is in the first region on the lowest speed side and the capacitance value of the capacitor circuit (14) is minimum, the advance angle becomes 0, and the phase voltage The integration circuit (10u) is set so that the phase delay angle φ of the rotational position estimation signal Hu with respect to Vu is 30 degrees, that is, the rotational position estimation signal Hu is equal to the conventional rotational position signal. As described above, since the capacitance value of the capacitor circuit (14) becomes large in the high speed region, the motor is driven based on the rotational position estimation signal having a lead angle of 0 or small at low speeds, and large advancement at high speeds. Lead angle control by corners is performed. For this reason, the motor can be driven in a wide range from low speed to high speed, and it is possible to cope with rapid acceleration / deceleration. Further, even if the load torque is large, there is no possibility of causing step-out.

  FIG. 5 conceptually shows the relationship between the rotational speed and the torque when the capacitance value of the capacitor circuit (14) of the integrating circuit (10) is fixed and when the integrated value is variable as in this embodiment. It is shown.

  In FIG. 5, a solid line A indicates a case where the capacitance value is variable, a broken line B indicates a case where the capacitance value is fixed to a small value, and a broken line C indicates a case where the capacitance value is fixed to a large value. When the capacitance value is fixed to a small value as in B, the characteristics at high speed and low torque are poor, and smooth high speed rotation cannot be performed. When the capacity value is fixed to a large value as in C, the characteristics at low speed and high torque are poor, and smooth low speed rotation cannot be performed. On the other hand, when the capacity value is made variable as in A, both the characteristics at low speed and high torque and at high speed and low torque are improved, and smooth rotation is possible in both the low speed range and the high speed range. .

FIG. 1 is a block diagram of a sensorless control device for a brushless DC motor showing an embodiment of the present invention. FIG. 2 is a block diagram showing an example of the configuration of the rotational position estimation signal generation device of FIG. FIG. 3 is a time chart showing an example of signals of each part of the sensorless control device. FIG. 4 is a time chart showing an example of signals of each part of the sensorless control device. FIG. 5 is a graph showing the relationship between the rotational speed and torque of the brushless DC motor.

Explanation of symbols

(1) Brushless DC motor
(2) DC power supply
(3) Rotation position estimation signal generator
(4) Energization control device
(10u) (10v) (10w) Integration circuit
(11u) (11v) (11w) Comparison circuit
(12) Switching device
(13) OP amplifier
(14) Capacitor circuit
(15a) (15b) (15c) Capacitor
(16b) (16c) switch

Claims (2)

Using an integration circuit and a comparison circuit in which a capacitor circuit is connected in parallel to an OP amplifier, a rotational position estimation signal for each phase is generated from the three-phase voltage in an analog manner, and a direct current is generated based on the rotational position estimation signal for each phase. A method of controlling a brushless motor using a permanent magnet without using a rotational position detection sensor by controlling energization from a power source to three phases,
A sensorless control method for a brushless motor, wherein the capacitance value of the capacitor circuit is switched based on a rotation speed. Rotation position estimation signal generating means for generating a rotation position estimation signal for each phase in an analog manner from three-phase phase voltages using an integration circuit and a comparison circuit in which a capacitor circuit is connected in parallel to an OP amplifier, and rotation of each phase An apparatus for controlling a brushless motor using a permanent magnet without using a rotational position detection sensor, comprising an energization control means for controlling energization from a DC power source to a three-phase based on a position estimation signal,
The capacitor circuit includes a plurality of capacitors arranged in parallel and a switch connected in series to a predetermined capacitor,
A sensorless control device for a brushless motor, characterized in that the rotational position estimation signal generating means includes switching means for switching the capacitance value of the capacitor circuit by turning on and off the switch based on a rotational speed.

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