JP2013070468A - Drive unit of brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make step-out hard to occur in a transient state of a brushless motor.SOLUTION: In a slow speed operation region where a brushless motor is rotationally driven below a first rotation speed N1, an energizing mode is switched according to a comparison result between a phase voltage of a non-energizing phase and a threshold. In a middle speed operation region where the brushless motor is rotationally driven at or above the first rotation speed N1 and at or below a second rotation speed N2, the energizing mode is switched when a second condition that the phase voltage of the non-energizing phase crosses a reference voltage is established and the time required for rotation at a prescribed angle from the state elapses or when a first condition that the phase voltage of the non-energizing phase crosses a prescribed voltage is established (S362-S368). Also, in a high speed operation region where the brushless motor is rotationally driven faster than the second rotation speed N2, the energizing mode is switched when the second condition that the phase voltage of the non-energizing phase crosses the reference voltage is established (S362, S369).

Description

  The present invention relates to a brushless motor driving apparatus.

  As a technique for driving a brushless motor without a sensor, as described in JP-A-11-341869 (Patent Document 1), an induced voltage (magnetic saturation voltage) of a non-conduction phase is compared with a predetermined voltage, A technique for sequentially switching the energization mode for each phase has been proposed.

JP-A-11-341869

  By the way, since the predetermined voltage compared with the induced voltage is set according to the motor rotation speed calculated from the switching period of the energization mode, it involves a time delay. For this reason, in a transient state in which the command rotational speed of the motor changes suddenly, there is a possibility that a deviation occurs between the actual rotational speed (actual rotational speed) and the calculated rotational speed.

  SUMMARY OF THE INVENTION Accordingly, in view of the problems of the prior art, an object of the present invention is to provide a brushless motor drive device that suppresses the divergence even in a transient state and hardly causes step-out.

  For this reason, the brushless motor drive device that rotationally drives the brushless motor has a plurality of energization mode switching means, and changes the energization mode switching method according to the rotation state of the brushless motor.

  Step-out and the like can be made difficult to occur in a transient state.

1 is a schematic configuration diagram of a hydraulic pump system for an automobile AT (Automatic Transmission). It is a circuit diagram which shows the structure of a motor control apparatus and a brushless motor. It is a block diagram which shows the structure of a controller. It is a time chart which shows the electricity supply pattern of a brushless motor. It is a flowchart which shows the drive control of a brushless motor. It is a flowchart of the subroutine which drives a brushless motor. It is a flowchart of the subroutine which drives a brushless motor. It is explanatory drawing of the map which sets a target motor rotational speed. It is explanatory drawing of the method of setting the limiting value of a duty ratio. It is explanatory drawing of the other method which sets the limiting value of a duty ratio. It is explanatory drawing of the correlation with the induced voltage and duty ratio of a non-energized phase. It is explanatory drawing of the phase terminal voltage detection period of a non-energized phase. It is explanatory drawing of the map which sets the predetermined value which determines whether the brushless motor rotated the predetermined angle. Problems and solutions when the actual rotational speed of the motor is suddenly reduced are shown. (A) is an explanatory diagram of the cause of the error, and (B) is an explanatory diagram of the solution. A problem and a solution when the actual rotational speed of the motor suddenly increases are shown, (A) is an explanatory diagram of the cause of the error, and (B) is an explanatory diagram of the solution.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows a schematic configuration of a hydraulic pump system for an automobile AT, which is an example of an application target of a brushless motor drive device.

  In the automobile AT hydraulic pump system, as an oil pump for supplying oil to the transmission 7 and the actuator 8, a mechanical oil pump 6 driven by an output of an engine (not shown) and an electric oil pump driven by a motor. 1 is provided.

  The engine control system also includes an idle stop control function that stops the engine when the automatic stop condition is satisfied and restarts the engine when the automatic start condition is satisfied. Since the mechanical oil pump 6 also stops its operation while the engine is stopped due to the idle stop, the oil pump 1 and the actuator 8 are supplied with oil by operating the electric oil pump 1 during the idle stop. Supply.

  The electric oil pump 1 is driven by a directly connected brushless motor (three-phase synchronous motor) 2. The brushless motor 2 is controlled by a motor control unit (MCU) 3 based on a command from an AT control unit (ATCU) 4.

  The motor control device (drive device) 3 drives and controls the brushless motor 2 to drive the electric oil pump 1, and supplies oil from the oil pan 10 to the transmission 7 and the actuator 8 via the oil pipe 5.

  During engine operation, the oil in the oil pan 10 is supplied to the transmission 7 and the actuator 8 via the oil pipe 9 by the engine-driven mechanical oil pump 6, and at this time, the brushless motor 2 is turned off (stopped). In addition, the flow of oil toward the electric oil pump 1 is blocked by the check valve 11.

  When the engine is idle stopped, the rotational speed of the mechanical oil pump 6 is decreased and the oil pressure of the oil pipe 9 is decreased. Therefore, the AT control device 4 issues a motor start command in synchronization with the engine idle stop. Send to 3

Upon receiving the start command, the motor control device 3 starts the brushless motor 2 to rotate the electric oil pump 1 and starts supplying oil by the electric oil pump 1.
When the discharge pressure of the mechanical oil pump 6 decreases while the discharge pressure of the electric oil pump 1 exceeds the valve opening pressure of the check valve 11, the oil is supplied to the oil pipe 5, the electric oil pump 1, It circulates through the path of the check valve 11, the transmission 7, the actuator 8, and the oil pan 10.

  In this embodiment, the brushless motor 2 drives the electric oil pump 1 of the hydraulic pump system. In addition to this, a brushless motor that drives an electric water pump used for circulating engine cooling water in a hybrid vehicle or the like. The target device driven by the brushless motor 2 is not limited to the oil pump.

FIG. 2 shows details of the motor control device 3 and the brushless motor 2.
The motor control device 3 has a motor drive circuit 212 and a controller 213 with a built-in computer, and the controller 213 communicates with the AT control device 4.

  The brushless motor 2 is a three-phase DC (Direct Current) brushless motor (three-phase synchronous motor), and a U-phase, V-phase, and W-phase three-phase winding 215u, 215v, 215w is connected to a cylindrical stator (not shown). And a permanent magnet rotor (rotor) 216 is rotatably provided in a space formed at the center of the stator.

  The motor drive circuit 212 includes a circuit in which switching elements 217a to 217f including antiparallel diodes 218a to 218f are connected in a three-phase bridge and a power supply circuit 219. The switching elements 217a to 217f are, for example, FETs (Field Effect Transistor)

  The control terminals (gate terminals) of the switching elements 217a to 217f are connected to the controller 213, and on / off of the switching elements 217a to 217f is controlled by a pulse width modulation (PWM) operation by the controller 213.

  The controller 213 is a circuit that calculates an applied voltage (input voltage) of the brushless motor 2 and generates a pulse width modulation signal (PWM signal) to be output to the motor drive circuit 212 based on the applied voltage. As shown in FIG. 3, the controller 213 includes a PWM generator 251, a gate signal switch 252, an energization mode determiner 253, a comparator 254, a voltage threshold switch 255, a voltage threshold learner 256, and a non-energized phase voltage selector. A container 257.

The PWM generator 251 is a circuit that generates a pulse wave modulated PWM wave based on an applied voltage command (command voltage).
The energization mode determiner 253 is a device that sequentially outputs a mode command signal for determining the energization mode (switching mode) of the motor drive circuit 212, and the energization mode is set to 6 by using the mode switching trigger signal output from the comparator 254 as a trigger. Switch to the street. The energization mode indicates a two-phase selection pattern in which a pulse voltage is applied among the three phases.

  The gate signal switching unit 252 determines the operation by which each of the switching elements 217a to 217f of the motor drive circuit 212 is switched based on the mode command signal that is the output of the energization mode determination unit 253, and according to this determination , Six gate pulse signals are output to the motor drive circuit 212.

  The voltage threshold value switching unit 255 is a circuit that sequentially generates and switches threshold values in the energization mode switching control based on the comparison between the pulse induced voltage of the non-energized phase and the threshold value. It is determined based on a mode command signal which is an output of H.253.

  The non-conduction phase voltage selector 257 selects a detection value of the non-conduction phase voltage from the three-phase terminal voltages Vu, Vv, Vw of the brushless motor 2 in accordance with the mode command signal, and the comparator 254 and the voltage threshold learning device 256 is a circuit to output to 256. The terminal voltage of the non-conduction phase is strictly a voltage between the ground GND and the terminal, but in the present embodiment, a neutral point voltage is separately detected, and the neutral point voltage and the GND-terminal are detected. The terminal voltages Vu, Vv, and Vw are obtained by obtaining the difference from the voltage.

  The comparator 254 compares the threshold value output from the voltage threshold value switch 255 with the voltage detection value (detection value of the pulse induced voltage) of the non-conduction phase voltage output from the non-conduction phase voltage selector 257, thereby The switching timing is determined, and a mode switching trigger is output to the energization mode determiner 253 based on the determination result. The pulse-induced voltage is a voltage induced in the non-conducting phase by applying a pulse voltage for two phases, and the saturation state of the magnetic circuit changes depending on the position of the rotor (magnetic pole position). An induced voltage corresponding to the position is generated in the non-energized phase, and the position of the rotor can be estimated from the induced voltage of the non-energized phase to detect the switching timing of the energized mode.

  The voltage threshold value learning unit 256 is a device that updates and stores a threshold value used for determination of switching timing of the energization mode. Since the pulse induced voltage of the non-energized phase detected for the determination of the switching timing varies due to manufacturing variations of the brushless motor 2, detection variations of the voltage detection circuit, and the like, a fixed value is set as a threshold for the variation of the induced voltage. If is used, the switching timing of the energization mode is erroneously determined. Therefore, the voltage threshold learning unit 256 detects the pulse induced voltage at the magnetic pole position corresponding to the switching timing of the energization mode, thereby correcting the threshold to be close to the induced voltage generated at the actual switching timing, and the voltage threshold switching The threshold value stored in the device 255 is replaced with the correction result.

FIG. 4 shows a voltage application state to each phase in each energization mode.
The energization mode is composed of six energization modes (1) to (6) that are sequentially switched every 60 degrees of electrical angle. In each energization mode (1) to (6), a pulse is applied to two phases selected from three phases. Apply voltage (pulse voltage).

  In the present embodiment, the angular position of the rotor that performs switching from the energization mode (3) to the energization mode (4) with the angular position of the U-phase coil as the reference position (angle 0 deg) of the rotor (magnetic pole). Rotor for switching from energization mode (5) to energization mode (6) to 30 deg for the magnetic pole position), 90 deg for the angular position of the rotor that switches from energization mode (4) to energization mode (5) The angle position of the rotor is switched to 150 deg, the angle position of the rotor that switches from the energization mode (6) to the energization mode (1) is set to 210 deg, and the rotor that switches from the energization mode (1) to the energization mode (2) Is set to 270 deg, and the angular position of the rotor for switching from the energization mode (2) to the energization mode (3) is set to 330 deg.

  In the energization mode (1), the switching element 217a and the switching element 217d are turned on, and all others are turned off, so that the voltage V is applied to the neutral point in the U phase and the neutral point in the V phase. On the other hand, a voltage −V is applied, and a current flows from the U phase toward the V phase.

  In the energization mode (2), the switching element 217a and the switching element 217f are turned on, and all others are turned off, whereby the voltage V is applied to the neutral point in the U phase and the neutral point in the W phase. On the other hand, a voltage −V is applied, and a current flows from the U phase to the W phase.

  In the energization mode (3), the switching element 217c and the switching element 217f are turned on, and all others are turned off, so that the voltage V is applied to the neutral point in the V phase and the neutral point in the W phase. On the other hand, a voltage −V is applied, and a current flows from the V phase toward the W phase.

  In the energization mode (4), the switching element 217b and the switching element 217c are turned on, and all others are turned off, so that the voltage V is applied to the neutral point in the V phase and the neutral point in the U phase. On the other hand, a voltage −V is applied, and a current flows from the V phase to the U phase.

  In the energization mode (5), the switching element 217b and the switching element 217e are turned on, and all others are turned off, so that the voltage V is applied to the neutral point in the W phase and the neutral point in the U phase. On the other hand, a voltage −V is applied, and a current flows from the W phase to the U phase.

  In the energization mode (6), the switching element 217e and the switching element 217d are turned on, and all others are turned off, so that the voltage V is applied to the neutral point in the W phase and the neutral point in the V phase. On the other hand, a voltage −V is applied, and a current flows from the W phase toward the V phase.

  In the case of such energization control, for example, in the energization mode (1), the switching element 217a and the switching element 217d are turned on, and all others are turned off to apply the voltage V to the U phase, A voltage -V was applied to the phase, and a current was allowed to flow from the U phase to the V phase, but the upper switching element 217c was driven with a PWM wave having a phase opposite to that of the PWM wave that drives the lower switching element 217d. In the complementary control system, the upper switching element 217c is turned off when the lower switching element 217d is on, and the upper switching element 217c is turned on when the lower switching element 217d is off. It is possible to perform energization control in each energization mode (1) to (6).

  Thus, by switching the six energization modes (1) to (6) every electrical angle of 60 deg, each switching element 217 a to 217 f is energized for 120 deg every 240 deg, as shown in FIG. 4. The energization method is called a 120 degree energization method.

FIG. 5 shows an outline of drive control of the brushless motor 2 by the motor control device 3.
In step 301 (abbreviated as “S301” in the figure, the same applies hereinafter), whether or not the threshold learning condition used for determining the switching timing of the energization mode, in other words, the operating condition of the voltage threshold learning unit 256 is satisfied. Determine whether. Specifically, the threshold learning condition is that a request for driving the brushless motor 2 is not generated immediately after the power is turned on or immediately after the electric oil pump 1 is stopped. If the learning condition is satisfied, the routine proceeds to step 302 where threshold learning is performed.

An example of the threshold learning process is shown below.
For example, when learning the threshold value V4-5 used for determining switching from the energization mode (4) to the energization mode (5), the permanent magnet rotor 216 is first positioned at an angle corresponding to the energization mode (3). . When an applied voltage corresponding to the energization mode (3), that is, Vu = 0, Vv = Vin, Vw = −Vin is applied to each phase, the permanent magnet rotor 216 is added to the combined magnetic flux of the U phase, the V phase, and the W phase. When pulled, torque is generated, and the north pole of the permanent magnet rotor 216 rotates to an angle of 90 deg. Then, after the voltage application corresponding to the energization mode (3) is performed, it is estimated that the positioning to the angle of 90 deg is completed after the time required for the permanent magnet rotor 216 to rotate to the angle of 90 deg. .

  The angle 90 deg at which the permanent magnet rotor 216 is attracted when the phase energization corresponding to the energization mode (3) is performed is an angular position for switching from the energization mode (4) to the energization mode (5).

  When the positioning of the permanent magnet rotor 216 to the angle of 90 deg is completed, the voltage application pattern corresponding to the energization mode (4) from the voltage application pattern corresponding to the energization mode (3), that is, Vu = −Vin, Vv. = Vin, Vw = 0. Then, immediately after switching from the applied voltage corresponding to the energization mode (3) to the applied voltage corresponding to the energization mode (4), the terminal voltage Vw of the W phase that is a non-energized phase in the energization mode (4) is detected. Based on this terminal voltage Vw, the threshold value V4-5 used for switching determination from the energization mode (4) to the energization mode (5) is updated and stored.

  That is, the switching from the energization mode (4) to the energization mode (5) is set so as to be performed at an angle of 90 deg as described above, in other words, whether the angle is 90 deg. Whether or not the timing for switching from 4) to energization mode (5) has come is determined based on the terminal voltage Vw of the W phase that is the non-energization phase in energization mode (4).

  Here, by continuing the applied voltage corresponding to the energization mode (3), it is possible to position at the angular position (90 deg) for switching from the energization mode (4) to the energization mode (5). When switching from the energization mode (3) to the energization mode (4), the W-phase terminal voltage Vw immediately after switching to the energization mode (4) indicates the terminal voltage V of the non-energization phase at the angular position of 90 deg.

  Therefore, the energization mode (4) to the energization mode (5) based on the W-phase terminal voltage Vw immediately after switching from the state in which the applied voltage corresponding to the energization mode (3) is continued to the energization mode (4). The threshold value V4-5 used for the determination of switching to is updated and stored. When the W-phase terminal voltage Vw, which is the non-energized phase in the energization mode (4), crosses the threshold V4-5 (when the W-phase terminal voltage Vw = the threshold V4-5), the energization mode Switching from (4) to energization mode (5) is executed.

Update learning can be performed in the same manner for threshold values used for switching other energization modes.
In the threshold update process, the terminal voltage V of the non-energized phase at the angular position at which the energization mode is switched may be stored as a threshold as it is, or the previous threshold value and the non-energized phase obtained this time may be stored. The weighted average value with the terminal voltage V may be stored as a new threshold value, and furthermore, the moving average value of the terminal voltage V of the non-conduction phase obtained over a plurality of past times may be stored as a new threshold value. Good.

  Further, if the terminal voltage V of the non-energized phase obtained this time is a value within the normal range stored in advance, the threshold value is updated based on the terminal voltage V of the non-energized phase obtained this time, and the terminal voltage V is out of the normal range. If it is, update of the threshold value based on the terminal voltage V of the non-conducting phase obtained this time is prohibited, and the threshold value may be held as the previous value.

  Further, the design value is stored as the initial value of the threshold value, and in the unlearned state where the threshold value has never been learned, the switching value of the energization mode is determined using the initial value (design value) as the threshold value. Like that.

  The voltage of the non-conduction phase fluctuates to the negative side with respect to the reference voltage. A common threshold is set in the mode switching from (1) → (2), (3) → (4), (5) → (6). A common threshold can be set in the mode switching from (2) → (3), (4) → (5), (6) → (1) with the energized phase voltage swinging to the plus side with respect to the reference voltage. .

  For example, the threshold value V4-5 learned as described above is used as a common threshold value in mode switching from (2) → (3), (4) → (5), (6) → (1), and (1) In (2), (3) → (4), (5) → (6) mode switching, a threshold having the same absolute value as the threshold V4-5 can be used as a common threshold.

However, the threshold learning is not limited to the above, and various known learning processes can be employed as appropriate.
As described above, when the threshold value used for determining the mode switching timing is learned in step 302 and when it is determined in step 301 that the learning condition is not satisfied, the process proceeds to step 303.

  In step 303, it is determined whether or not a drive request for the electric oil pump 1 (brushless motor 2) is generated. In the case of the present embodiment, the generation of an idle stop request indicates the generation of a drive request for the electric oil pump 1. And if the drive request | requirement of the electric oil pump 1 has generate | occur | produced, it will progress to step 304, and the switching timing to the next electricity supply mode is compared by comparing the voltage of the non-energized phase in the electricity supply mode at that time, and a threshold value. The sensorless motor drive control for driving the brushless motor 2 is performed by sequentially switching the energization mode.

  The brushless motor 2 is activated by, for example, positioning it at a position of 90 deg by applying a voltage according to the energization mode (3), then switching to the energization mode (5), and starting to rotate the brushless motor 2, When the angle position for switching from 5) to energization mode (6) is 150 deg, the voltage of the V phase, which is the non-energized phase in energization mode (5), is changed from energization mode (5) to energization mode ( It is determined when the threshold value V5-6 used for determining switching to 6) is crossed, and switching to the energization mode (6) is performed. Thereafter, the voltage of the non-energized phase is compared with the threshold value, and the energization mode is sequentially switched.

On the other hand, if the drive request for the electric oil pump 1 has not occurred, the routine is terminated by bypassing step 304.
Details of the motor drive control in step 304 will be described based on the flowcharts of FIGS.

  In step 351, for example, a target rotational speed [rpm] of the brushless motor 2 is calculated with reference to a map in which a target rotational speed corresponding to the oil temperature of ATF (Automatic Transmission Fluid) is set as shown in FIG. . Here, in the map shown in FIG. 8, the target rotational speed increases linearly as the oil temperature rises, but the present invention is not limited to such characteristics. When the brushless motor 2 drives the water pump, the target rotational speed may be set to a higher rotational speed as the engine coolant temperature increases.

  In step 352, an applied voltage to be applied to the brushless motor 2 is calculated based on the target rotational speed of the brushless motor 2 and the actual rotational speed (actual rotational speed) as follows. That is, when the applied voltage is controlled by PI (proportional integral) by rotational feedback, if “rotational speed deviation = target rotational speed−actual rotational speed” is set, “applied voltage = rotational speed deviation × P (proportional) gain + rotation” The applied voltage can be obtained from the equation “speed deviation integral value × I (integral) gain”. The same applies to other control methods, for example, PID (proportional integral derivative) control. The actual rotation speed uses the calculated value calculated in step 361, which will be described later, but the detected value detected by a known sensor or the like may be used. The applied voltage may be a known method such as a method of calculating based on a deviation between the target discharge pressure and the actual discharge pressure of the electric oil pump 1 or a required torque.

In step 353, the lower limit value of the duty ratio for PWM control of the phase current is set by the following method.
For example, as shown in FIG. 9, a PWM counter valley (a point where the counter value changes from decrease to increase) that repeats increase / decrease for each carrier period in PWM control, in other words, near the center of the pulse width PW of the pulse application voltage. When the A / D conversion timing (sampling timing) of the non-energized phase is used, the period (voltage fluctuation time) in which the pulse induced voltage of the non-energized phase fluctuates immediately after the application of the pulse voltage (immediately after the rise) is If it is longer than 2, A / D conversion (sampling) of the pulse induced voltage of the non-energized phase is performed while the pulse induced voltage is swinging, and the pulse induced voltage of the non-energized phase is accurately detected. It cannot be detected. If the time required for the A / D conversion processing of the pulse-induced voltage of the non-energized phase (A / D conversion time from the start to completion of A / D conversion) is longer than ½ of the pulse width PW, A / During the D conversion process, the application of voltage to the phase energization stops, and in this case as well, the pulse-induced voltage of the non-energized phase cannot be detected accurately, and the brushless motor 2 may step out. is there.

Therefore, the lower limit value of the duty ratio is calculated according to the following equation.
Lower limit = max (voltage fluctuation time, A / D conversion time) × 2 / carrier cycle × 100
According to this equation, twice the longer of the voltage fluctuation time and the A / D conversion time is set to the minimum pulse width PWmin, and the pulse-induced voltage A of the non-conduction phase is varied while the pulse-induced voltage fluctuates. It can suppress that / D conversion (sampling) is performed, and can suppress that the application of the voltage with respect to an energized phase stops during an A / D conversion process.

  In the PWM control, the peak of the PWM counter that repeatedly increases and decreases for each carrier cycle (the point at which the counter value changes from increasing to decreasing) is used as the A / D conversion timing (sampling timing) of the voltage of the non-energized phase, or PWM switching Even when the non-energized phase voltage is A / D conversion timing (sampling timing), the lower limit value of the duty ratio is set as described above.

  The voltage fluctuation time and A / D conversion time can use values obtained in advance through experiments and simulations, and set the lower limit value of the duty ratio based on the measurement result obtained by measuring the voltage fluctuation time in step 353. You can also

  When the A / D conversion timing (sampling timing) of the voltage of the non-energized phase can be set to an arbitrary timing, as shown in FIG. 10, the A / D conversion processing is started immediately after the voltage fluctuation time has elapsed. As a result, A / D conversion (sampling) of the pulse induced voltage of the non-conducting phase can be performed within the shortest possible pulse, and the pulse induction of the non-conducting phase is performed while the pulse induced voltage fluctuates. It can suppress that A / D conversion (sampling) of a voltage is performed, and can suppress that the application of the voltage with respect to an energized phase stops during an A / D conversion process.

Specifically, the lower limit value of the duty ratio is calculated according to the following equation.
Lower limit value = (voltage fluctuation time + A / D conversion time) / carrier cycle × 100
That is, if the pulse width PW is longer than the sum of the voltage fluctuation time and the A / D conversion time, and A / D conversion is started immediately after the voltage fluctuation time has elapsed, the pulse-induced voltage is changing. It is possible to suppress the A / D conversion (sampling) of the pulse induced voltage of the non-energized phase, and it is possible to suppress the voltage application to the energized phase from being stopped during the A / D conversion process.

  Further, the magnitude of the pulse-induced voltage in the non-energized phase varies depending on the duty ratio. As shown in FIG. 11, when the duty ratio decreases, the pulse-induced voltage in the non-energized phase also decreases, and when the duty ratio is small, the voltage There is a possibility that the voltage becomes lower than the detection resolution, and the switching timing of the energization mode cannot be determined.

  Therefore, the minimum value of the duty ratio that generates a pulse induced voltage (voltage exceeding the resolution of voltage detection) that can be detected by the voltage detection circuit may be set as the lower limit value. In this case, a larger duty ratio can be used as a final duty ratio among any one of the lower limit values obtained from the above two formulas and the lower limit value obtained in consideration of the resolution of voltage detection. .

  By setting the lower limit value of the duty ratio in this way, it is possible to suppress the A / D conversion (sampling) of the pulse induced voltage of the non-energized phase while the pulse induced voltage fluctuates, and A / The application of the voltage to the energized phase during the D conversion process can be prevented from being stopped, and furthermore, a voltage that can be detected as a pulse-induced voltage can be generated to determine the timing for switching the energization mode. The occurrence of step-out in 2 can be suppressed.

In step 354, the duty ratio is set based on the applied voltage (input voltage) set in step 352 and the lower limit value of the duty ratio set in step 353.
First, the basic duty [%] is calculated from “basic duty = applied voltage / power supply voltage × 100”. Here, as the power supply voltage, the immediately preceding power supply voltage that has been A / D converted in step 356 described later may be used. When the basic duty is larger than the lower limit value, the basic duty is set as the duty ratio. On the other hand, when the basic duty is lower than the lower limit value, the duty ratio may be lower than the lower limit value by setting the lower limit value as the duty ratio. Limit to not.

  In the case of the hydraulic pump system as in the present embodiment, it is not required to control the motor rotation speed with high accuracy, and an applied voltage higher than the request is given. The discharge amount can be secured, and there is no occurrence of a decrease in hydraulic pressure or insufficient lubrication. Further, when the brushless motor 2 drives the water pump, even if the duty ratio is limited, at least a cooling water circulation amount equal to or more than the required amount can be secured, and the occurrence of engine overheating can be suppressed.

  In step 355, a non-energized phase (phase for detecting a pulse induced voltage) corresponding to the energization mode at that time is selected. Specifically, the W phase is selected in the energization mode (1), the V phase is selected in the energization mode (2), the U phase is selected in the energization mode (3), and the energization mode ( In the case of 4), the W phase is selected, in the energization mode (5), the V phase is selected, and in the energization mode (6), the U phase is selected. Such a non-energized phase is selected by the non-energized phase voltage selector 257 based on a signal from the energized mode determiner 253.

In step 356, A / D conversion (sampling) of the phase terminal voltage of the non-energized phase selected in step 355 and the power supply voltage is performed at a predetermined timing.
Here, the detection period (A / D conversion timing) of the phase terminal voltage of the non-energized phase will be described with reference to FIG. 12 taking the energization mode (3) as an example. In the energization mode (3), the voltage V is applied to the V phase, the voltage -V corresponding to the instruction voltage is applied to the W phase by the pulse width modulation operation, and the current flows from the V phase to the W phase. The detection phase is the U phase, and the phase terminal voltage of the U phase is detected during the ON period of the switching element 217f in the lower stage of the W phase.

  Further, a commutation current is generated immediately after the switching of the energization mode, and if the voltage detected in the commutation current generation section is used, the switching timing of the energization mode is erroneously determined. Therefore, the voltage detection value immediately after the switching of the energization mode is not used for the determination of the switching timing for a predetermined number of times from the first time. The predetermined number of times can be variably set according to the motor rotation speed and current (motor load). The higher the motor rotation speed and the higher the motor current, the larger the predetermined number of times. The power supply voltage is also A / D converted at the same timing as the phase terminal voltage of the non-energized phase.

In step 357, for example, the phase voltage is calculated from the phase terminal voltage and the power supply voltage subjected to A / D conversion in step 356, using the expression “phase voltage = phase terminal voltage−power supply voltage / 2”.
In step 358, it is determined whether or not the rotational speed of the brushless motor 2 is less than a first rotational speed N1 that defines a boundary between the low speed operation area and the medium speed operation area. If the motor rotation speed is less than the first rotation speed N1, it is determined that the brushless motor 2 is in the low speed operation region, and the routine proceeds to step 359. If the motor rotation speed is equal to or higher than the first rotation speed N1, it is determined that the brushless motor 2 is in the medium speed operation region or the high speed operation region, and the process proceeds to step 362.

  As the first rotational speed N1, for example, a first predetermined value for determining the transition from the medium speed operation region to the low speed operation region and the second for determining the transition from the low speed operation region to the medium speed operation region. By setting a predetermined value (> first predetermined value) and providing a so-called “hysteresis”, even if switching between the low speed operation region and the medium speed operation region is suppressed from being repeated in a short time Good (same below).

  In step 359, based on the phase voltage and the threshold learned in step 302, it is determined whether it is the switching timing of the energization mode in the low speed operation region. Specifically, in the case of the energization mode (1) at that time, when the phase voltage becomes equal to or lower than the threshold value V1-2, it is determined that it is the switching timing to the energization mode (2). In the case of the energization mode (2), when the phase voltage becomes equal to or higher than the threshold value V2-3, it is determined that it is the switching timing to the energization mode (3). ), It is determined that it is the switching timing to the energization mode (4) when the phase voltage is equal to or lower than the threshold value V3-4, and the current mode is the energization mode (4) at that time. Is determined to be the timing for switching to the energization mode (5) when the phase voltage becomes equal to or higher than the threshold V4-5, and if the phase voltage is the energization mode (5) at that time, the phase voltage is the threshold Switching timing to energization mode (6) when V5-6 or lower If determined, were energization mode (6) at that time that there is, it is determined that when the phase voltage becomes the threshold V6-1 or a switching timing of the energization mode (1). If it is determined that it is the switching timing of the energization mode, the process proceeds to step 360. On the other hand, if it is determined that it is not the switching timing of the energization mode, the subroutine is terminated.

  In step 360, the mode is switched to the next energization mode. Specifically, if the current mode is the current mode (1), the mode is switched to the current mode (2). If the current mode is the current mode (2), the mode is switched to the current mode (3). When the current mode is (3), the mode is switched to the current mode (4). When the current mode is (4), the mode is switched to the current mode (5). ) Is switched to the energization mode (6), and if it is the energization mode (6) at that time, the mode is switched to the energization mode (1).

  In step 361, the rotational speed of the brushless motor 2 is calculated based on the energization mode switching period. Specifically, the time interval at which the energization mode is switched is measured, and the rotation speed is calculated from this time interval. For example, when the number of pole pairs of the brushless motor 2 is 3, the rotation speed can be obtained from the equation “rotation speed = 60/3 / time interval”.

  In step 362, whether or not the rotational speed of the brushless motor 2 is equal to or lower than the second rotational speed N2 that delimits the boundary between the high-speed operation region and the medium-speed operation region. In short, the motor rotational speed is the first rotational speed. It is determined whether or not the vehicle is in a “medium speed operation region” that is N1 or more and the second rotation speed N2 or less. If the motor rotation speed is equal to or lower than the second rotation speed N2, it is determined that the brushless motor 2 is in the medium speed operation region, and the process proceeds to step 363. If the motor rotation speed is higher than the second rotation speed N2, it is determined that the brushless motor 2 is in the high speed operation region, and the process proceeds to step 369.

  In step 363, a predetermined voltage for determining the switching timing of the energization mode in the medium speed operation region is set based on the motor rotation speed, current, and temperature. That is, the switching timing of the energization mode varies depending on the motor rotation speed, the induced voltage constant, and the magnetic saturation voltage. The induced voltage constant varies with the motor temperature, and the magnetic saturation voltage varies with the motor temperature and the motor current. For this reason, since the switching timing of the energization mode changes according to the motor rotation speed, current, and temperature, the predetermined voltage is set based on the motor rotation speed, current, and temperature.

  Specifically, an induced voltage constant representing the relationship with the motor rotation speed is acquired in advance, and the induced voltage constant is corrected according to the motor temperature. The induced voltage constant increases as the motor temperature decreases. Also, the magnetic saturation voltage is acquired in advance and corrected according to the motor temperature and motor current. The magnetic saturation voltage increases as the motor temperature decreases and increases as the motor current increases. Then, the predetermined voltage is set from the expression “predetermined voltage = motor rotation speed × induced voltage constant + magnetic saturation voltage”.

  In step 364, it is determined whether or not the relationship between the phase voltage and the predetermined voltage satisfies the first condition in order to determine whether or not it is the switching timing of the energization mode in the medium speed operation region. That is, in the energization mode (2), (4) or (6), whether or not “phase voltage ≧ predetermined voltage” is satisfied, and in the energization mode (1), (3) or (5), “phase voltage It is determined whether or not “≦ predetermined voltage”. Here, in the energization mode (2), (4) or (6), the predetermined voltage takes a positive value, and in the energization mode (1), (3) or (5), the predetermined voltage is a negative value. Take. If the relationship between the phase voltage and the predetermined voltage satisfies the first condition, the process proceeds to step 360. If the relationship between the phase voltage and the predetermined voltage does not satisfy the first condition, the process proceeds to step 365.

  In step 365, whether or not the relationship between the phase voltage and the reference voltage (for example, power supply voltage / 2) satisfies the second condition in order to determine whether it is the switching timing of the energization mode in the medium speed operation region. Determine whether or not. That is, in the energization mode (2), (4) or (6), whether or not “phase voltage ≧ reference voltage” is satisfied, and in the energization mode (1), (3) or (5), “phase voltage It is determined whether or not “≦ reference voltage”. Here, in the energization mode (2), (4) or (6), the reference voltage takes a positive value, and in the energization mode (1), (3) or (5), the reference voltage is a negative value. Take. If the relationship between the phase voltage and the reference voltage satisfies the second condition, the process proceeds to step 366. If the relationship between the phase voltage and the reference voltage does not satisfy the second condition, the subroutine is terminated.

  In step 366, the elapsed time is measured to determine whether the brushless motor 2 has rotated a predetermined angle (for example, 30 degrees) after the relationship between the phase voltage and the reference voltage satisfies the second condition. Counts up the counter. Here, when the time measurement by the counter has not been started, the time measurement is started.

  In step 367, a predetermined value corresponding to the time required for the brushless motor 2 to rotate by a predetermined angle is set. Specifically, as shown in FIG. 13, a predetermined value corresponding to the motor rotation speed is set with reference to a map having a characteristic that the predetermined value gradually decreases as the motor rotation speed increases.

  In step 368, it is determined whether or not the counter value has reached a predetermined value or not, in other words, whether or not the brushless motor 2 has rotated a predetermined angle after the relationship between the phase voltage and the reference voltage satisfies the second condition. . If the counter value exceeds the predetermined value, the process proceeds to step 360. If the counter value does not exceed the predetermined value, the subroutine is terminated.

  In step 369, it is determined whether or not the relationship between the phase voltage and the reference voltage satisfies the second condition in order to determine whether or not it is the switching timing of the energization mode in the high-speed operation region. If the relationship between the phase voltage and the reference voltage satisfies the second condition, the process proceeds to step 360. On the other hand, if the relationship between the phase voltage and the reference voltage does not satisfy the second condition, the subroutine is terminated.

  Therefore, the brushless motor 2 that drives the electric oil pump 1 is driven by sequentially switching the energization modes in the low speed operation region, the medium speed operation region, and the high speed operation region as follows.

  In the low-speed operation area, the result of comparison between the phase voltage of the non-energized phase and the threshold value, that is, when the phase voltage of the non-energized phase crosses the threshold value corresponding to the current energizing mode, switching to the next energizing mode It is done. Here, since the threshold value is a value learned from the induced voltage at the magnetic pole position corresponding to the switching timing of the energization mode, even if there are manufacturing variations of the brushless motor 2, detection variations of the voltage detection circuit, etc. The corrected value is taken. For this reason, the switching of the energization mode in the low speed operation region is performed at an appropriate timing, and the step-out of the brushless motor 2 can be made difficult to occur.

  In the medium speed operation region, when the phase voltage of the non-energized phase crosses the predetermined voltage according to the motor rotation speed, current and temperature (condition 1), or after the phase voltage of the non-energized phase crosses the reference voltage When the time required for the rotor to rotate by a predetermined angle has passed (condition 2), the mode is switched to the next energization mode. In short, in the medium speed operation region, the energization mode is switched when at least one of the two conditions is met.

  Here, the condition 1 specifically means that the phase voltage of the non-energized phase changes from the third voltage lower than the predetermined voltage to the fourth voltage equal to or higher than the predetermined voltage, or from the fourth voltage to the third voltage. This is the case when the voltage changes. Further, the condition 2 specifically refers to the phase voltage of the non-conduction phase changing from the first voltage lower than the reference voltage to the second voltage equal to or higher than the reference voltage, or from the second voltage to the first voltage. This is a case where the time required to rotate a predetermined angle from that state has elapsed.

  As shown in FIG. 14 (A), when the motor rotation speed is suddenly decreased from B to A, the rotation speed (calculation rotation speed) obtained by calculation is B, whereas the actual rotation speed is A. A rotational speed error occurs only by B-A. In this case, since the predetermined voltage for determining the switching timing of the energization mode is set based on the calculated rotational speed B that is larger than the actual rotational speed A, the absolute value thereof becomes large. For this reason, the phase voltage does not cross the predetermined voltage, and the energization mode is not switched according to the condition 1. However, as shown in FIG. 14B, since the phase voltage crosses the reference voltage, Condition 2 is satisfied at the time when the rotor rotates by a predetermined angle, and the energization mode is switched.

  Note that when the motor rotation speed suddenly increases from A to B, the predetermined voltage for determining the switching timing of the energization mode is set based on the calculated rotation speed A smaller than the actual rotation speed B. The absolute value becomes small, and the malfunction that a phase voltage does not cross a predetermined voltage does not occur.

  Further, as shown in FIG. 15A, when the motor rotation speed suddenly increases from A to B, the calculated rotation speed is A while the actual rotation speed is B, and the rotor rotates by a predetermined angle. An error (time error) corresponding to the rotation speed error (B-A) occurs with respect to the time to perform. In this case, since the time for which the rotor rotates by a predetermined angle is set based on the calculated rotational speed A that is slower than the actual rotational speed B, it is longer than the actually required time. For this reason, the timing at which the condition 2 is satisfied is delayed. However, as shown in FIG. 15B, Condition 1 is satisfied when the phase voltage crosses the predetermined voltage, and the energization mode is switched.

  When the motor rotation speed is suddenly decreased from B to A, the time for which the rotor rotates by a predetermined angle is set based on the calculated rotation speed B faster than the actual rotation speed A. It becomes shorter than the time, and the timing at which the condition 2 is satisfied is not delayed.

  Therefore, when at least one of the condition 1 and the condition 2 is satisfied, the energization mode is switched, and the brushless motor 2 is stepped out even in a transient state in which the motor rotation speed rapidly decreases or increases. It becomes difficult to improve the responsiveness.

  In the high-speed operation region, when the phase voltage of the non-energized phase crosses the reference voltage, in other words, the phase voltage of the non-energized phase changes from the first voltage that is less than the reference voltage to the second voltage that is greater than or equal to the reference voltage. Or when it changes from the 2nd voltage to the 1st voltage, it switches to the next energization mode. For this reason, there is no delay in switching the energization mode, and the step-out of the brushless motor 2 can be made difficult to occur.

  Here, when the brushless motor 2 shifts from the low speed operation region to the medium speed operation region or the high speed operation region, in order to suppress the step-out in the transient state, until the actual rotational speed of the brushless motor 2 converges to the target rotational speed. The energization mode may be switched when the phase voltage of the non-energized phase crosses the reference voltage. In this case, the target rotational speed of the brushless motor 2 may have a width defined by the upper limit value and the lower limit value in order to avoid the infinite convergence.

  Further, the controller 213 further includes a comparator (comparator) that determines the switching timing of the energization mode by comparing the voltage detection value of the non-energization phase output from the non-energization phase voltage selector 257 with the reference voltage. In this case, it may be determined whether or not the phase voltage has crossed the reference voltage based on the determination result output from the comparator instead of the phase voltage of the non-conduction phase.

  Here, technical ideas other than the claims that can be grasped from the above embodiment will be described together with effects.

(A) In the brushless motor drive device according to claim 1 or 2,
The brushless motor driving apparatus, wherein the predetermined voltage is set according to a temperature, a current, and a rotation speed of the brushless motor.
According to the above configuration, the predetermined voltage to be compared with the induced voltage of the non-energized phase can be adapted to the switching timing of the energization mode that changes according to the rotation speed, induced voltage constant, and magnetic saturation voltage of the brushless motor. For this reason, the energization mode is switched in accordance with the operating state of the brushless motor, and step-out can be made difficult to occur.

(B) In the brushless motor drive device according to claim 2,
The target rotational speed is a brushless motor driving device having a width defined by an upper limit value and a lower limit value.
According to the said structure, it can avoid that the actual rotational speed of a brushless motor does not converge on target rotational speed forever.

(C) In the brushless motor drive device according to claim 1, claim 2, (b) or (b),
A comparator for comparing the voltage of the non-energized phase with the reference voltage;
A brushless motor drive device that determines whether or not the induced voltage of the non-energized phase crosses the reference voltage based on a comparison result of the comparator.
According to the above configuration, whether or not the induced voltage of the non-energized phase crosses the reference voltage is determined from the comparison result of the comparator, so that the control load can be reduced.

  DESCRIPTION OF SYMBOLS 1 ... Electric oil pump, 2 ... Brushless motor, 3 ... Motor control apparatus, 212 ... Motor drive circuit, 213 ... Controller, 215u, 215v, 215w ... Winding, 216 ... Permanent magnet rotor, 217a-217f ... Switching element 251 ... PWM generator 252 ... Gate signal switcher 253 ... Energization mode determiner 254 ... Comparator 255 ... Voltage threshold switcher 256 ... Voltage threshold learner 257 ... Non-energized phase voltage selector

Claims (2)

A brushless motor drive device that rotationally drives the brushless motor by switching the energization mode for each phase of the brushless motor having a plurality of windings,
In the low-speed operation region where the brushless motor is rotationally driven at a speed lower than the first rotational speed, the energization mode is switched according to the comparison result between the induced voltage of the non-energized phase and the threshold value,
In a medium speed operation region where the brushless motor is driven to rotate at a speed greater than or equal to the first rotational speed and less than or equal to the second rotational speed, the induced voltage of the non-energized phase crosses the reference voltage and rotates a predetermined angle from that state When the time required for the elapse of time or when the induced voltage of the non-energized phase crosses a predetermined voltage, the energization mode is switched,
In a high-speed operation region where the brushless motor is driven to rotate faster than the second rotation speed, the energization mode is switched when the induced voltage of the non-energized phase crosses the reference voltage.
A drive device for a brushless motor. When the brushless motor moves from the low speed operation region to the medium speed operation region or the high speed operation region, the induced voltage of the non-energized phase is increased until the actual rotational speed of the brushless motor converges to the target rotational speed. When the reference voltage is crossed, the energization mode is switched.
The brushless motor driving apparatus according to claim 1, wherein: