JP6297868B2 - Brushless motor control device and control method - Google Patents

Description

  The present invention relates to a control device and a control method for a brushless motor, and more particularly to a control device and a control method for performing sensorless switching determination of a power supply mode of a three-phase brushless motor.

  As a conventional brushless motor control device and control method, in a three-phase brushless motor, an energization mode in which a pulse voltage corresponding to a PWM (Pulse Width Modulation) signal is applied to two phases is changed to a non-energized phase during application of the pulse voltage. It is known that switching is performed when the induced pulse induced voltage crosses a threshold value determined for each energization mode (see, for example, Patent Document 1).

  Here, since the pulse induced voltage fluctuates immediately after the pulse voltage is applied to the two phases, if the duty of the PWM signal is reduced in order to rotate the brushless motor at a low speed, the pulse induced voltage is reduced within the fluctuation period of the pulse induced voltage. Sampling is likely to occur, and the switching timing of the energization mode may be erroneous.

  Therefore, in the brushless motor control device and control method of Patent Document 1, the pulse induced voltage of the non-conduction phase is detected in one cycle (hereinafter referred to as “main cycle”) of the plurality of cycles of the PWM signal. The duty of the PWM signal in the main period (hereinafter referred to as “main period duty”) is limited so that the pulse-induced voltage is not sampled within the fluctuation period, and other periods other than the main period among the plurality of periods of the PWM signal (Hereinafter referred to as “adjustment cycle”) PWM signal duty (hereinafter referred to as “adjustment cycle duty”) is set smaller than the main cycle duty, and the average duty obtained by averaging the main cycle duty and the adjustment cycle duty is The duty set in the rotation speed feedback control etc. (hereinafter referred to as “set duty”) It is adjusted.

JP 2013-66343 A

  By the way, a switching element such as an FET (Field Effect Transistor) that switches energization to each phase of a brushless motor has a dead zone that does not turn on when the duty of a pulse signal input to its control terminal approaches zero. .

  For this reason, when the adjustment cycle duty is reduced to an area close to 0, the average duty (hereinafter referred to as “output average duty”) obtained by averaging the main duty and the adjustment cycle of the output duty of the switching element is calculated from the set duty. There is a divergence and the step changes with respect to the set duty.

  Therefore, when the rotational speed feedback control is performed, if the set duty is set in the vicinity of the discontinuity where the output average duty changes stepwise, the output average duty may fluctuate and the actual rotational speed may cause hunting. was there.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a brushless motor control device and control method in which the difference between the set duty and the output average duty is reduced.

For this reason, in the brushless motor control device and control method according to the present invention, the energization mode in which the switching element applies a pulse voltage corresponding to the PWM signal to the two phases of the three-phase brushless motor is induced in the non-energized phase. assuming that switch based on a pulse induced voltage that, when setting the duty of the PWM signal is less than the first predetermined value, a predetermined one cycle among a plurality successive periods of the PWM signal, a first phase of the two phases As a period for applying the PWM signal to the switching element connected to the first, the duty of one predetermined period is limited to the first predetermined value as the period for detecting the pulse induced voltage, and the predetermined one is limited to the first predetermined value. The average duty obtained by averaging the duty of the cycle and the duty of a cycle other than the predetermined one of the plurality of cycles of the PWM signal is a set duty cycle. As it will be, by adjusting the duty of the other periods, when the second predetermined value or more set duty is the duty of the other period less than the first predetermined value is zero or more, the other cycle by duty While the PWM signal is applied to the switching element connected to the first phase of the two phases, when the set duty is less than a second predetermined value where the duty of the other period is less than zero, the PWM by the duty of the other period The signal is applied to the switching element connected to the second phase of the two phases, and when the set duty is less than the second predetermined value, the duty of the other period is turned on by the switching element connected to the second phase. When the value is a dead zone, the duty of the other period is decreased and corrected by a predetermined amount so as to deviate from the dead band, and the duty of a predetermined period is increased and corrected by a predetermined amount. The

  According to the brushless motor control device and control method of the present invention, the deviation between the set duty and the output average duty of the switching element is reduced, and the linearity of the output average duty with respect to the set duty is improved. Rotation speed hunting in the feedback control can be suppressed.

It is a block diagram which shows an example of the cooling system which cools an engine. It is a circuit block diagram which shows an example of a brushless motor and its control apparatus. It is a block diagram which shows the structure of a part of control unit. It is a time chart which shows an example of the electricity supply mode of a brushless motor. It is a timing chart which shows the detection timing of a pulse induced voltage. It is a time chart which shows another detection timing of a pulse induced voltage. It is a time chart which shows the main period and adjustment period of a PWM signal. It is a flowchart which determines the drive conditions establishment of an electric water pump. It is a flowchart which shows an example of a main routine among motor control processes. It is a flowchart which illustrates the first half part of a sensorless control subroutine. It is a flowchart which illustrates the second half part of a sensorless control subroutine. It is explanatory drawing which shows an example of the calculation of target rotational speed. It is a time chart which shows the 1st application duty setting. It is a time chart which shows the 2nd application duty setting. It is a time chart which shows the 3rd applied duty setting. It is explanatory drawing which shows the relationship between a setting duty, a main period duty, and an adjustment period duty, (a) is a PWM signal duty of a control unit, (b) is an output duty of a switching element, (c) is an output average of a switching element Duty. It is explanatory drawing which shows an example of the switching characteristic of a switching element. It is explanatory drawing which shows the responsiveness of the switching element in a dead zone, (a) is a PWM signal output of a control unit, (b) is a gate voltage waveform, (c) is a switching output of a switching element. It is explanatory drawing which shows the responsiveness of the switching element in a dead zone, (a) is a PWM signal output of a control unit, (b) is a gate voltage waveform, (c) is a switching output of a switching element. It is explanatory drawing which shows the relationship between the setting duty, the main period duty after correction | amendment, and adjustment period duty, (a) is the PWM signal duty of a control unit, (b) is the output duty of a switching element, (c) is a switching element Output average duty. It is explanatory drawing which shows the relationship between the main period duty after correction | amendment other than a setting duty and adjustment period duty, (a) is a PWM signal duty of a control unit, (b) is an output duty of a switching element, (c) is This is the output average duty of the switching element.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows an example of a cooling system that cools an engine by circulating a refrigerant.

  Cooling water as a refrigerant that has cooled the cylinder block, cylinder head, and the like of the engine 10 mounted on the vehicle is guided to the radiator 16 provided with the electric radiator fan 14 via the first cooling water passage 12. . The cooling water guided to the radiator 16 exchanges heat with the outside air when passing through the radiator core to which the fins are attached, and the temperature thereof decreases. Then, the cooling water whose temperature has been lowered by passing through the radiator 16 is returned to the engine 10 via the second cooling water passage 18. In addition to the cooling water, LLC (Long Life Coolant) may be used as the coolant for cooling the engine 10.

  Further, the first cooling water passage 12 and the second cooling water passage 18 are connected via a bypass passage 20 so that the cooling water discharged from the engine 10 bypasses the radiator 16. An electric thermostat 22 that opens and closes the passage area of the bypass passage 20 in multiple stages or continuously from fully open to fully closed is arranged at the junction between the downstream end of the bypass passage 20 and the second coolant passage 18. It is installed. The electric thermostat 22 is an open / close valve that opens and closes a valve by utilizing the thermal expansion of the built-in wax, for example, by a built-in heater driven according to the duty (duty ratio) of the PWM signal via a drive circuit. Can be configured as a valve. Therefore, the ratio of the cooling water passing through the radiator 16 can be changed by controlling the electric control thermostat 22 with the duty.

  A mechanical water pump 24 and an electric water pump 26 that forcibly circulate cooling water between the engine 10 and the radiator 16 between the downstream end of the second cooling water passage 18 and the electric control thermostat 22. Are arranged respectively. The mechanical water pump 24 is attached so as to close the cooling water inlet of the engine 10 and is driven by, for example, a camshaft of the engine 10. The electric water pump 26 is driven by a brushless motor, which will be described later, which is a driving source different from the engine 10 so that the cooling performance can be exhibited or the heating function can be maintained even when the engine 10 is stopped by the idle stop function. The electric power system of the vehicle is configured to drive the electric water pump 26 even during idle stop.

  A water temperature sensor as a cooling water temperature detecting means for detecting the temperature of cooling water discharged from the engine 10 (cooling water temperature) as a control system for controlling the driving of the radiator fan 14, the electric thermostat 22, and the electric water pump 26. 28, a vehicle speed sensor 30 for detecting the vehicle speed, a temperature sensor 32 for detecting the outside air temperature, a rotation speed sensor 34 for detecting the engine rotation speed, and a load sensor 36 for detecting the engine load are attached. The output signals of the water temperature sensor 28, the vehicle speed sensor 30, the temperature sensor 32, the rotational speed sensor 34, and the load sensor 36 are input to an engine control unit (hereinafter referred to as “ECU”) 38 having a built-in computer, and the ROM ( The radiator fan 14, the electric thermostat 22 and the electric water pump 26 are controlled in accordance with a control program stored in a read-only memory or the like.

  The ECU 38 repeatedly determines whether or not a driving condition for driving the electric water pump 26 is satisfied, at least during the operation of the engine 10. When the ECU 38 determines that this drive condition is satisfied, it outputs a drive command signal to the electric water pump 26, while when it determines that the drive condition is not satisfied, the electric water pump A stop command signal for stopping or prohibiting the drive 26 is output.

  In the cooling system of the engine 10 as described above, when the engine 10 is started, in order to improve the fuel consumption of the engine 10 by suppressing the generation of hot spots in which only the coolant temperature in the engine 10 and its vicinity increases, The pump 26 causes the need to circulate the cooling water at a relatively low flow rate that does not affect the friction of the engine 10. For this reason, the brushless motor that drives the electric water pump 26 is required to expand the controllable rotational speed range to the low rotational speed side.

  In this embodiment, the brushless motor 100 drives an electric water pump 26 incorporated in a cooling system that cools the engine 10, but in addition, an electric motor incorporated in a hydraulic pump system for an automatic transmission. The oil pump may be driven, and the target device driven by the brushless motor 100 is not limited to the electric water pump 26.

FIG. 2 shows an example of the brushless motor 100 that drives the electric water pump 26 and its control device.
The brushless motor 100 is a three-phase DC (Direct Current) brushless motor (three-phase synchronous motor), and is a cylinder in which U-phase, V-phase, and W-phase three-phase windings 110u, 110v, and 110w that are star-connected are not shown. A rotor (permanent magnet rotor) 120 is rotatably provided in a space formed in the center of the stator.

  A control device (hereinafter referred to as “motor control device”) 200 of the brushless motor 100 includes a drive circuit 210 and a control unit 220 including a microcomputer, and the control unit 220 communicates with the ECU 38. . The motor control device 200 is not limited to the one disposed in the vicinity of the brushless motor 100. For example, at least the control unit 220 of the motor control device 200 may be formed integrally with the ECU 38 or another control unit.

  The drive circuit 210 includes a circuit in which switching elements 214a to 214f including antiparallel diodes 212a to 212f are connected in a three-phase bridge, and a power supply circuit 230. The switching elements 214a to 214f are, for example, FETs And an IGBT (Insulated Gate Bipolar Transistor), etc., which are composed of semiconductor elements used for power control. The control terminals (gate terminals) of the switching elements 214a to 214f are connected to the control unit 220, and the control unit 220 controls on / off of the switching elements 214a to 214f by pulse width modulation (PWM). The voltage applied to the brushless motor 100 is controlled.

  In PWM control, a PWM signal is generated by comparing a value (voltage level) of a carrier signal set by a triangular wave with a value (voltage level) of an instruction signal set based on a command value of an applied voltage. Thus, the timing for turning on / off each of the switching elements 214a to 214f is detected.

  The drive control of the brushless motor 100 by the control unit 220 is performed without a sensor that does not use a sensor that detects the position information of the rotor 120. Further, the control unit 220 uses a sine wave drive method according to the motor rotation speed. And switching to the rectangular wave drive system.

  The sine wave driving method is a method of driving the brushless motor 100 by applying a sine wave voltage to each phase. In this sine wave driving method, the position information of the rotor 120 is obtained from the induced voltage (speed electromotive voltage) generated by the rotation of the rotor 120, while the motor rotation speed is detected during the rotor position detection cycle based on the speed electromotive voltage. Is used to estimate the position of the rotor 120, calculate a three-phase output set value from the estimated position of the rotor 120 and the PWM duty, and control the direction and strength of the current by the difference in interphase voltage to generate a three-phase alternating current. Flow in each phase.

  The rectangular wave driving method is a method of driving the brushless motor 100 by sequentially switching a selection pattern (energization mode) of two phases to which a pulse voltage is applied among the three phases for each position of a predetermined rotor 120.

  In this rectangular wave driving method, the position information of the rotor 120 is obtained from the voltage (transformer induced voltage, pulse induced voltage) induced in the non-energized phase by applying a pulsed voltage to the energized phase, and at the switching timing of the energized mode. A certain angular position is detected.

  Here, since the output level of the speed electromotive voltage detected for position detection in the sine wave driving method decreases as the motor rotation speed decreases, the position detection accuracy decreases in the low rotation speed range. On the other hand, the pulse induced voltage detected for position detection in the rectangular wave driving method can be detected even in a low rotational speed range including the motor stop state, and the position detection accuracy can be maintained even in the low rotational speed range.

  Therefore, the control unit 220 controls the brushless motor 100 by the sine wave drive method in a high rotation speed region where the position information can be detected with sufficient accuracy by the sine wave drive method, that is, in a region where the motor rotation speed is higher than the set rotation speed. The so-called high speed sensorless control is performed.

  In addition, the control unit 220 performs so-called low-speed sensorless control in which the brushless motor 100 is controlled by the rectangular wave driving method in a low rotation speed range where position information cannot be detected with sufficient accuracy by the sine wave driving method. Note that the low rotational speed range in which position information cannot be detected with sufficient accuracy by the sine wave driving method includes a motor rotational speed range lower than the set rotational speed and a time when the motor is activated.

  Further, in the PWM control of the brushless motor 100, the control unit 220 determines the duty ratio of the PWM control according to the deviation between the motor rotation speed and the target rotation speed, for example, and brings the motor rotation speed close to the target rotation speed.

FIG. 3 is a functional block diagram illustrating a part related to the low speed sensorless control in the control unit 220.
The control unit 220 includes an applied voltage calculation unit 302, a PWM generation unit 304, a gate signal switching unit 306, an energization mode determination unit 308, a comparison unit 310, a voltage threshold switching unit 312, a voltage threshold learning unit 314, and a non-energized phase voltage selection unit. 316, a main cycle duty setting unit 318, an adjustment cycle duty setting unit 320, and a duty correction unit 322.

  The applied voltage calculation unit 302 calculates the target rotation speed of the brushless motor 100 and the actual rotation speed that is the actual rotation speed of the brushless motor 100, and applies the applied voltage based on the calculated target rotation speed and the actual rotation speed. The command value of is calculated.

  The PWM generator 304 generates a PWM signal that has been subjected to pulse width modulation based on the command value of the applied voltage calculated by the applied voltage calculator 302.

The energization mode determination unit 308 is a device that outputs a mode command signal for determining the energization mode of the drive circuit 210, and switches the energization mode in six ways using the mode switching trigger signal output from the comparison unit 310 as a trigger.
The energization mode refers to a two-phase selection pattern in which a pulse voltage is applied among the three phases of the U, V, and W phases of the brushless motor 100, and the first energization that allows current to flow from the U phase toward the V phase. Mode M1, a second energization mode M2 for flowing current from the U phase to the W phase, a third energization mode M3 for flowing current from the V phase to the W phase, and a fourth for flowing current from the V phase to the U phase There are six energization modes: energization mode M4, fifth energization mode M5 in which current flows from the W phase toward the U phase, and sixth energization mode M6 in which current flows from the W phase toward the V phase.
Then, the energization mode determination unit 308 outputs a mode command signal for instructing any one of the first energization mode M1 to the sixth energization mode M6 in accordance with the mode switching trigger signal output from the comparison unit 310.

  The gate signal switching unit 306 is generated by the mode command signal that is the output of the energization mode determination unit 308 and the PWM generation unit 304 to determine how the switching elements 214a to 214f of the drive circuit 210 are switched. Based on the determined PWM signal, six gate pulse signals are output to the motor drive circuit 210 according to the determination.

  The voltage threshold switching unit 312 sequentially switches and outputs the voltage threshold used for detecting the switching timing of the energization mode according to the energization mode, and the threshold switching timing is based on the mode command signal output from the energization mode determination unit 308. To be determined.

The non-conduction phase voltage selection unit 316 selects a detection value of the non-conduction phase voltage from the three-phase terminal voltages Vu, Vv, Vw of the brushless motor 100 according to the mode command signal, and compares the comparison unit 310 and the voltage threshold learning unit. To 314.
Although the terminal voltage of the non-conduction phase is strictly a voltage between the ground GND and the terminal, in the present embodiment, the neutral point voltage is detected, and the voltage between the neutral point and the ground GND and the terminal is detected. The terminal voltage Vu, Vv, Vw is obtained by obtaining the difference from the voltage.

  The comparison unit 310 compares the threshold value output by the voltage threshold value switching unit 312 with the voltage detection value (detection value of the pulse induced voltage) of the non-conduction phase voltage output by the non-conduction phase voltage selection unit 316, thereby In other words, it is detected whether or not the rotor position (magnetic pole position) for switching the energization mode is reached, and a mode switching trigger is output to the energization mode determination unit 308 when the switching timing is detected.

The voltage threshold learning unit 314 is a device that updates and stores a threshold used for determination of the switching timing of the energization mode.
Since the pulse-induced voltage of the non-energized phase (open phase) varies depending on manufacturing variations of the brushless motor 100, detection variations of the voltage detection circuit, etc., it is possible to erroneously determine the switching timing of the energized mode if a fixed value is used as the threshold value. There is sex.
Therefore, the voltage threshold learning unit 314 detects a pulse induced voltage at a predetermined magnetic pole position where the energization mode is switched, and performs threshold learning processing for correcting the threshold stored in the voltage threshold switching unit 312 based on the detection result. carry out.

  The energization mode is composed of the six energization modes M1 to M6 as described above. In the rectangular wave driving method, these energization modes M1 to M6 are sequentially switched at the switching angle position set at an electrical angle interval of 60 deg. The brushless motor 100 is driven by sequentially switching the two phases to which the pulse voltage (pulse voltage) is applied.

  As shown in FIG. 4, when the angular position of the U-phase coil is set to the reference position (angle = 0 deg) of the rotor (magnetic pole), the control unit 220 has an angular position (magnetic pole position) of 30 deg. At a certain time, switching from the third energization mode M3 to the fourth energization mode M4 is performed, and when the rotor angular position is 90 deg, switching from the fourth energization mode M4 to the fifth energization mode M5 is performed. When the position is 150 deg, the fifth energization mode M5 is switched to the sixth energization mode M6, and when the rotor angular position is 210 deg, the sixth energization mode M6 is switched to the first energization mode M1. When the rotor angular position is 270 deg, the first energization mode M1 is switched to the second energization mode M2, and when the rotor angular position is 330 deg, the second energization mode M2 is switched to the second energization mode M2. To switch to the conduction mode M3.

  The voltage threshold value switching unit 312 of the control unit 220 stores the non-energized phase voltage (pulse induced voltage) at the angular position of the rotor that switches the energization mode as a threshold value, and can be updated, and the energization mode at that time A threshold value corresponding to is output.

  The comparison unit 310 outputs a signal indicating that the angle for performing switching to the next energization mode is detected when the voltage of the non-energization phase reaches the threshold value, and the energization mode determination unit 308 is energized based on the signal. Perform mode switching.

  Here, when the duty of the PWM signal generated by the PWM generator 304 is less than the lower limit duty (first predetermined value), the main cycle duty setting unit 318, the adjustment cycle duty setting unit are as follows. 320 and the duty correction unit 322, and then output to the gate signal switching unit 306.

  The pulse-induced voltage in the non-energized phase is detected while the PWM signal is on and the pulse voltage is applied to the two phases, but as shown in FIGS. 5 and 6, immediately after the application of the pulse voltage is started. Since ringing in which the pulse induced voltage fluctuates occurs, the duty of the PWM signal is reduced to shorten the ON period in order to rotate the brushless motor 100 at a low speed (the pulse voltage application time is shortened). In other words, the pulse induced voltage is sampled within the ringing period, which may erroneously detect the pulse induced voltage and erroneously determine the switching timing of the energization mode.

Therefore, as shown in FIG. 7, the main cycle duty setting unit 318 is a predetermined one of a plurality of consecutive cycles (for example, N cycle: N is an integer of 2 or more) of the PWM signal generated by the PWM generation unit 304. to detect a pulse induced voltage in the non-energized phase in the main cycle is one cycle, a main cycle duty D ₁ is the duty of the PWM signal in the main cycle, the lower limit as the pulse induced voltage is not sampled in the ringing period duty Dmin Limiting means for limiting to (first predetermined value) is provided. As a result, the detection accuracy of the pulse induced voltage is improved, the determination of the switching timing of the energization mode is performed stably, and the occurrence of step-out of the brushless motor 100 is suppressed.

Further, as shown in FIG. 7, the adjustment cycle duty setting unit 320 is configured to adjust the PWM signal in the adjustment cycle, which is a cycle other than the main cycle among the N cycles of the continuous PWM signal generated by the PWM generation unit 304. The duty, that is, the adjustment cycle duty D _{2 to DN} is set smaller than the main cycle duty D ₁ (= Dmin) set by the main cycle duty setting unit 318, and the main cycle duty D ₁ and the adjustment cycle duty D _{2 are set.} average duty _Dav to a to D _N and averaged _{{= (D 1 + D 2} + ···· + D N) / N} is adjusted so that the set duty Dt is the duty which is set according to the rotational speed To make adjustments. Thus, the main period duty D ₁ instead of being unable to below the lower limit duty Dmin, to reduce the duty adjustment cycle is another cycle other than within the main period of the N periods of the PWM signal, substantially in N periods of the PWM signal Thus, the set duty Dt is applied to increase the operating range of the electric water pump 26 toward the low rotation speed side.

Further, as will be described later, the duty correction unit 322 uses the main cycle duty D ₁ set by the main cycle duty setting unit 318 and the adjustment cycle duties D _{2 to} D _N set by the adjustment cycle duty setting unit 320, Correction means for correcting according to the responsiveness of the switching elements 214a to 214f with respect to the duty of the PWM signal is made.

The value of N that specifies the number of periods of the main period and the adjustment period can be changed based on various parameters such as the actual rotational speed of the brushless motor 100, the target rotational speed, the PWM signal setting duty Dt, and the PWM carrier frequency. but, in the following embodiments, for convenience, N = 2 by setting the control unit 220, to secure the detection accuracy of the pulse induced voltage by the main period duty D _1, the main period duty D ₁ and the adjustment period duty D ₂ The following description assumes that the set duty Dt is substantially applied.

  FIG. 8 shows the contents of the process relating to the driving condition of the brushless motor 100 (electric water pump 26), which is repeatedly performed in the ECU 38 when the ignition key is turned on.

In step 1001 (abbreviated as “S1001” in the figure, the same applies hereinafter), it is determined whether or not the drive condition of the electric water pump (electric WP) 26, that is, the brushless motor 100 is satisfied.
For example, the power supply voltage of the brushless motor 100 exceeds a predetermined voltage, no abnormality is detected in the brushless motor 100 or the drive circuit 210 in various diagnostic processes, the power supply relay of the brushless motor 100 is turned on, The driving conditions for the brushless motor 100 may include a request for driving the water pump 26 and the water temperature or oil temperature of the engine 10 being equal to or higher than a predetermined temperature.

  In the case of the cooling system shown in FIG. 1, the establishment / non-establishment of the drive condition of the electric water pump 26 is determined by the motor control device 200 (control unit 220) that has acquired various types of information from the ECU 38. Can do.

  If it is determined that the drive condition of the brushless motor 100 is satisfied, the process proceeds to step 1002, and the drive flag F is set to a value (for example, 1) indicating that the drive condition is satisfied, The data is stored in a writable storage device such as a RAM (Random Access Memory) (Yes). On the other hand, if it is determined that the driving condition of the brushless motor 100 is not satisfied, the process proceeds to step 1003 and the driving flag F is set to a value (for example, 0) that means that the driving condition is not satisfied. Is stored in RAM (No).

Next, FIG. 9 shows a main routine for controlling the brushless motor 100 (electric oil pump 26) repeatedly performed by the control unit 220 when the ignition key is turned on.
In step 2001, it is determined whether or not the driving flag F has changed from 0 to 1, that is, whether or not the driving condition of the brushless motor 100 has changed from the non-established state to the established state. If it is determined that the drive flag F has changed from 0 to 1, the process proceeds to step 2003 (Yes). If the drive flag F remains 0 or 1, or if the drive flag F has changed from 1 to 0, The process proceeds to step 2002 (No).

  In step 2002, it is determined whether or not the drive flag F is 0 in order to determine whether or not it is necessary to perform sensorless control of the brushless motor 100 described later. When the drive flag F is 0, the drive condition of the brushless motor 100 is not satisfied, and thus this control process is terminated to omit the sensorless control of the brushless motor 100 (Yes). On the other hand, when the drive flag F is 1, since the drive condition of the brushless motor 100 is satisfied, the process proceeds to step 2005 to execute the sensorless control (No).

  When it is determined in step 2001 that the drive condition has changed from the non-established state to the established state, the control unit 220 performs an estimation process of the initial position (magnetic pole position at the start of driving) of the brushless motor 100 in step 2003. It is determined whether or not a condition to perform is satisfied.

  For example, when a drive command is generated during the inertial rotation of the brushless motor 100, the brushless motor 100 may rotate so as to affect the estimation of the initial position between the start and completion of the estimation process. Therefore, the estimation process indicates that the rotational speed of the brushless motor 100 is equal to or lower than a predetermined speed, in other words, the induced voltage (speed electromotive voltage) generated by the rotation of the rotor 120 is equal to or lower than the predetermined voltage. Condition.

In other words, the predetermined speed in the initial position estimation process is an upper limit value of the motor rotation speed that can make the estimation error of the initial position within an allowable range, and the predetermined voltage is an induction generated at the upper limit rotation speed. Voltage (speed electromotive force).
Here, the predetermined speed can be a predetermined speed ≧ 0 rpm, and the initial position estimation process is performed in a motor stopped state or in a low-speed rotation state in which the change of the magnetic pole position in the time required for the estimation process is sufficiently small.

If the control unit 220 determines in step 2003 that the conditions for executing the initial position estimation process are not satisfied, that is, if the motor rotation speed exceeds the predetermined speed, the control unit 220 repeats the process in step 2003 and executes it. If it is determined that the condition is satisfied (motor rotational speed ≦ predetermined speed is satisfied), the routine proceeds to step 2004.
If the control unit 220 determines in step 2003 that the conditions for performing the initial position estimation process are not satisfied, the control unit 220 determines that the initial position cannot be estimated, and rotates the brushless motor 100 to a predetermined position. Positioning processing can be performed.

  In step 2004, the control unit 220 performs a process of estimating the initial position of the brushless motor 100, determines an energization mode for starting driving according to the initial position estimated in the estimation process, and based on the determination. Then, driving of the brushless motor 100 is started.

The outline of the initial position estimation process will be described. Energization is sequentially performed in each energization mode without rotating the brushless motor 100, and a pulse induced voltage induced in a non-energized phase (open phase) is acquired in each energization mode. .
Then, the initial position of the brushless motor 100 is detected by obtaining a difference in pulse induced voltage between the energization modes in a predetermined combination and comparing the level of the difference with each other. When the initial position (stop position) of the brushless motor 100 is detected, an optimum energization mode for starting driving from the initial position is determined.

  When the brushless motor 100 starts rotating, the control unit 220 proceeds to step 2005, and drives the brushless motor 100 by the sensorless control described above, that is, the rectangular wave driving method in the low speed region and the sine wave driving method in the high speed region.

  Next, the flowcharts of FIGS. 10 and 11 are subroutines showing the contents of sensorless control by rotational speed feedback in step 2005 of the flowchart of FIG.

In step 3001, the applied voltage calculation unit 302 calculates the target rotation speed of the brushless motor 100.
In the brushless motor 100 that rotationally drives the electric oil pump 26 of the present embodiment, for example, as shown in FIG. 12, in the first cooling water passage 12, the second cooling water passage 18, or the bypass passage 20 of the cooling system. The target rotational speed can be set to a higher rotational speed as the temperature of the cooling water passing through is higher. When the brushless motor 100 drives a hydraulic pump that supplies hydraulic pressure to an automatic transmission or the like, the target rotational speed is set to a higher rotational speed as the oil temperature (ATF (Automatic Transmission Fluid) oil temperature) is higher.

  In the cooling system of FIG. 1, the target rotation speed is calculated based on the coolant temperature information input by communication from the ECU 38 in the motor control device 200 (control unit 220). Instead, the ECU 38 After calculating the target rotational speed, the signal of the target rotational speed may be input to the motor control device 200 (control unit 220) by communication.

  In step 3002, the applied voltage calculation unit 302 calculates the actual rotational speed of the brushless motor 100 based on the switching period of the energization mode. Specifically, the applied voltage calculation unit 302 uses the mode switching trigger output from the comparison unit 310 to measure the time interval during which the energization mode is switched, and calculates the rotation speed from this time interval. For example, when the number of pole pairs of the brushless motor 100 is 3, the rotation speed can be obtained from the equation “rotation speed = 60/3 / time interval”.

  In step 3003, the applied voltage calculation unit 302 calculates a command value for the applied voltage (input voltage) based on the target rotation speed calculated in step 3001 and the actual rotation speed calculated in step 3002.

For example, the command value of the applied voltage (input voltage) is determined according to the following equation by proportional-integral control (PI control) based on the deviation between the target rotational speed and the actual rotational speed.
Applied voltage = Rotational speed deviation * Proportional gain + Rotational speed deviation integrated value * Integral gain Rotational speed deviation = Target rotational speed-Actual rotational speed

  However, the method for determining the command value of the applied voltage is not limited to the method based on the target rotational speed. For example, the command value of the applied voltage is based on the deviation between the target discharge pressure of the electric oil pump 26 and the actual discharge pressure. Known determination methods such as a method for determining the value of the applied voltage and a method for determining the command value of the applied voltage based on the required torque can be appropriately employed. Further, the calculation processing of the applied voltage for bringing the actual value closer to the target value is not limited to proportional integral control, and a known calculation processing method such as proportional integral differentiation control (PID control) can be appropriately employed.

In step 3004, the PWM generator 304 calculates a set duty Dt that is set to be applied to the brushless motor 100 based on the applied voltage (input voltage) determined in step 3003. Specifically, the set duty Dt (%) is calculated from the following equation.
Setting duty Dt = applied voltage / power supply voltage * 100

In step 3005, the PWM generator 304 determines whether or not the set duty Dt ≧ the lower limit duty Dmin is satisfied.
Here, as described above, the lower limit duty Dmin is the pulse voltage application time during which the pulse induced voltage of the non-energized phase can be detected without being affected by ringing, that is, the lower limit value of the duty at which the PWM signal is turned on (> 0). And is calculated based on actually measured values such as a ringing period and a sampling time, or stored in advance in a ROM (Read Only Memory) or the like.

For example, as shown in FIG. 5, the lower limit duty Dmin is a carrier signal valley that repeats increase / decrease for each carrier period in PWM control at the timing of starting sampling (A / D conversion) of the pulse-induced voltage of the non-energized phase. In other words, in the case of the vicinity of the center of the pulse width of the PWM signal, the sampling is suppressed during the ringing period, and the application of the pulse voltage to the two phases during the sampling is suppressed. Therefore, as shown by the following equation, it may be twice the longer of the ringing period and the sampling time.
Dmin = max (ringing period, sampling time) * 2 / carrier cycle * 100

Further, as shown in FIG. 6, for example, as shown in FIG. 6, the lower limit duty Dmin suppresses the sampling during the ringing period and starts the sampling immediately after the ringing period elapses. The lower limit duty Dmin may be calculated as shown by the following equation in order to prevent the application of the pulse voltage to the two phases from stopping.
Dmin = (ringing period + sampling time) / carrier cycle * 100

  Note that the pulse-induced voltage of the non-energized phase changes depending on the duty of the pulse voltage, and if the duty is small, the voltage becomes lower than the resolution of voltage detection, making it impossible to determine the switching timing of the energized mode. Therefore, if necessary, the minimum duty value for generating a pulse induced voltage exceeding the resolution of voltage detection may be set as the lower limit duty Dmin.

  When it is determined in step 3005 that the set duty Dt ≧ the lower limit duty Dmin is established, the process proceeds to step 3006 (Yes). On the other hand, if it is determined that the set duty Dt ≧ the lower limit duty Dmin does not hold, that is, it is determined that the set duty Dt <the lower limit duty Dmin, go to Step 3007 to avoid sampling the pulse induced voltage within the ringing period. Proceed (No).

  In step 3006, the PWM generator 304 sets the set duty Dt calculated in step 3004 as the first applied duty DA that is the duty of the PWM signal that is actually applied to the switching element, and the first applied duty. The PWM signal of DA (= Dt) is transmitted to the gate signal switching unit 306.

  With such setting of the first applied duty DA, as shown in FIG. 13, two of the three phases are energized, that is, switching elements (SW elements) connected to the upstream phase in the current direction. Control of the downstream lower switching element in any energization mode in which the upper one (hereinafter referred to as “upstream upper switching element”, hereinafter the same) is turned on and the downstream lower switching element is turned on / off. A PWM signal whose ON time ratio is specified by a set duty Dt is applied to the terminal as a gate signal. For example, in the energization mode M3 in which the upper switching element 214c connected to the V phase is turned on and the lower switching element 214f connected to the W phase is turned on / off, the control terminal of the switching element 214f A PWM signal having a set duty Dt is applied as a gate signal.

  Here, the PWM generator 304 not only turns on / off the downstream lower switching element according to the PWM signal but also generates a PWM signal by a complementary PWM method in order to flow current from the upstream phase toward the downstream phase. That is, as shown in FIG. 13, when the downstream lower stage switching element is on, the downstream upper stage switching element is off, and when the downstream lower stage switching element is off, the downstream upper stage switching element is on. For the downstream upper switching element, a PWM signal having a phase opposite to that of the PWM signal applied to the downstream lower switching element is generated. For example, in the energization mode M3, a PWM signal having a phase opposite to that applied to the W-phase lower switching element 214f is applied to the W-phase upper switching element 214e.

  The complementary PWM method is adopted as an example of the energization mode M3. When the switching element 214f on the lower side of the W phase, which is the downstream side, is turned from on to off, the current flows in the direction that has been flowing until then. In order to flow, it passes through the diode 212e connected in reverse parallel to the switching element 214e on the upper side of the W phase, but the forward resistance of the diode 212e is larger than the on-resistance in the switching portion of the switching element 214e. This is because if the switching element 214e is turned on, the current flows through the switching portion of the switching element 212e (for example, the channel of the FET) to reduce the current loss.

  Further, as shown in FIG. 13, the PWM signal applied to the downstream lower switching element is turned on in order to avoid a ground fault / short circuit that occurs when the downstream upper switching element and the downstream lower switching element are simultaneously turned on. A dead time Z in which both the downstream upper switching element and the downstream lower switching element are turned off is provided so that the OFF time of the PWM signal applied to the downstream upper switching element becomes longer than the time.

  As shown in FIG. 13, the PWM signal applied to the downstream lower switching element includes the value of the lower carrier signal and the value of the downstream instruction signal for generating the PWM signal applied to the downstream switching element. The PWM signal generated by comparison and applied to the downstream upper switching element compares the value of the upper carrier signal obtained by offsetting the potential level of the lower carrier signal with the value of the downstream instruction signal to provide a dead time. Can be generated.

  The above-described complementary PWM method, dead time setting, and PWM signal generation method will be described in the same manner in the second applied duty setting and the third applied duty setting described below. Omitted.

In step 3007, the PWM generator 304 determines whether or not the set duty Dt ≧ Dmin / 2 is satisfied. Note that the reason why the lower limit duty Dmin is divided by 2 is that, as described above, the value of N that specifies the number of periods of the main period and the adjustment period is set to N = 2. dt = Dmin / 2 to (second predetermined value) is _satisfied, in _{dt = (D 1 + D 2} ) / 2 = (Dmin + D 2) / 2 that equation, when to be adjusted periodically duty _{D 2} 0 is there.

  If it is determined in step 3007 that the set duty Dt ≧ the lower limit duty Dmin / 2 is established, the process proceeds to step 3008 (Yes). On the other hand, if it is determined that the set duty Dt ≧ the lower limit duty Dmin / 2 is not satisfied, that is, it is determined that the set duty Dt <the lower limit duty Dmin / 2, the process proceeds to step 3009 (No).

In step 3008, the main period duty setting unit 318 and the adjustment cycle duty setting portion 320, respectively, by setting the second applied duty DB consisting of primary cycle duty D ₁ and adjustment period duty D _2, the second applied duty The PWM signal of DB is transmitted to the duty correction unit 322.

Here, the main period duty D ₁ is set to the lower limit duty Dmin, so that no sampled pulse induced voltage in the ringing period. The adjustment period duty _{D 2} is in a range satisfying _{0 ≦ D 2 ≦ Dmin, (} D 2 = 2 × Dt-Dmin) obtained in accordance with the set duty Dt.

With such setting of the second applied duty DB, as shown in FIG. 14, in any energization mode, the on-time ratio is specified by the lower limit duty Dmin at the control terminal of the downstream lower switching element in the main cycle. While the PWM signal is applied as a gate signal, in the adjustment period, the value of the downstream instruction signal is changed, and the on-time ratio is set to D ₂ (= 2 × Dt−Dmin) at the control terminal of the downstream lower switching element. The PWM signal specified in (1) is applied as a gate signal. For example, in the energization mode M3 in which the upper switching element 214c connected to the V phase is turned on and the lower switching element 214f connected to the W phase is turned on / off, in the main period, the switching element 214f The PWM signal having the lower limit duty Dmin is applied as a gate signal to the control terminal of the same, and the PWM signal specified by D ₂ (= 2 × Dt−Dmin) is similarly applied to the control terminal of the switching element 214f in the adjustment period as the gate signal. Apply.

  Therefore, in the second applied duty DB, torque is generated in the positive rotation direction, which is the intended rotation direction by switching the energization mode, in the main cycle, while the current flowing in the main cycle is reduced in the adjustment cycle. Therefore, the torque generated in the same positive rotation direction as the main cycle is reduced so that the PWM signal specified by the set duty Dt equal to or higher than the lower limit duty Dmin / 2 can be applied, so to speak, the positive duty adjustment is performed. .

In step 3009, the main period duty setting unit 318 and the adjustment cycle duty setting unit 320, respectively, a main period duty _{D 1} equal to the lower limit duty Dmin, satisfy -Dmin ≦ _D 2 <0, i.e., minimizing the -Dmin value A third applied duty DC consisting of a negative adjustment cycle duty D ₂ is set, and a PWM signal of the third applied duty DC is transmitted to the duty correction unit 322.

  With such setting of the third applied duty DC, as shown in FIG. 15, in any energization mode, in the main period, the downstream instruction signal is set to a value that does not intersect the lower carrier signal and the upper carrier signal, and upstream. The side instruction signal is changed to a value that intersects the lower carrier signal and the upper carrier signal, and a PWM signal in which the on-time ratio is specified by the lower limit duty Dmin is applied to the control terminal of the downstream lower switching element as a gate signal.

On the other hand, in the adjustment cycle, instead of changing the downstream instruction signal to a value that does not cross the lower carrier signal and the upper carrier signal, the upstream instruction signal is changed to a value that intersects the lower carrier signal and the upper carrier signal, and A PWM signal whose on-time ratio is specified by | D ₂ | (= | 2 × Dt−Dmin |) is applied as a gate signal to the control terminal of the upstream lower switching element instead of the lower switching element. At this time, since the ON PWM signal is applied to the control terminal of the downstream upper switching element by the above-described complementary PWM method, the downstream upper switching element is the upstream side, and the upstream lower switching element is the downstream side. The voltage applied to the energized phase is reversed between the main period and the adjustment period.

  Therefore, at the third applied duty DC, torque is generated in the positive rotation direction that is the intended rotation direction by switching the energization mode in the main cycle, while in the negative rotation direction opposite to the positive rotation direction in the adjustment cycle. Torque is generated so that the PWM signal specified by the set duty Dt less than the lower limit duty Dmin / 2 can be applied, that is, negative duty adjustment is performed.

  In step 3010, the duty correction unit 322 corrects the second applied duty DB set in step 3008 according to the responsiveness of the switching elements 214a to 214f with respect to the duty of the PWM signal.

  In Step 3011, the duty correction unit 322 corrects the third applied duty DC set in Step 3009 according to the responsiveness of the switching elements 214 a to 214 f with respect to the duty of the PWM signal.

Here, the significance of the duty correction unit 322 correcting the second applied duty DB and the third applied duty DC will be described.
As shown in FIG. 16A, in the PWM signal output from the control unit 220 (gate signal switching unit 306) to the control terminals of the switching elements 214a to 214f, the second application duty DB and the third application duty DC, as average duty Dav that was limited to the lower limit duty Dmin main cycle duty D ₁ and adjustment period duty D ₂ averaged is directly proportional to the preset duty cycle Dt, by adjusting the adjustment period duty D _2, The set duty Dt can be applied substantially in two periods of the main period and the adjustment period of the PWM signal.

  However, as shown in FIG. 17, the switching elements 214a to 214f do not turn on in the range of 0% to X% of the duty of the PWM signal output from the control unit 220 to the switching elements 214a to 214f. For example, it has a dead zone in which no current flows through the FET channel. In addition, when the negative duty adjustment is performed in the setting of the third applied duty DC, the switching elements 214a to 214f are within the range of -X% to 0% of the duty of the PWM signal output from the control unit 220. Have a similar dead zone.

Therefore, as shown in FIGS. 16A and 16B, in the switching outputs of the switching elements 214a to 214f, the output adjustment cycle duty D ₂₁ is PWM output from the control unit 220 with respect to the same set duty Dt. Where the adjustment cycle duty D ₂ should be the same value as the signal adjustment cycle duty D ₂ , the adjustment cycle duty D ₂ is within the range where the switching elements 214 a to 214 f are in the dead zone −X% to X%, ie, the set duty Dt {(Dmin−X) / 2} to {(Dmin + X) / 2}, the switching elements 214a to 214f are fixed to 0 [%] at which they are not turned on. Therefore, as shown in FIG. 16C, the output average duty of the switching elements 214a to 214f does not change linearly with respect to the set duty Dt like the average duty Dav in FIG. Will change.

  Therefore, among the PWM signals output from the control unit 220, the second applied duty DB and the third applied duty DC are corrected in accordance with the responsiveness of the switching elements 214a to 214f with respect to the duty of the PWM signal to perform switching. The output average duty of the elements 214a to 214f is made to match the average duty Dav.

The switching elements 214a to 214f have dead zones for the following reasons.
When the switching element is, for example, a MOSFET (Metal Oxide Field-Effect Transistor), as shown in FIG. 18 (b), the gate voltage with respect to the source when n-type or p-type When the gate voltage with respect to the drain exceeds a predetermined threshold voltage TH, the switching elements 214a to 214f are turned on as shown in FIG. 18 (c), and a current flows, as shown in FIG. 18 (b). As described above, when the gate voltage falls below the predetermined threshold voltage TH, the switching elements 214a to 214f are turned off to interrupt the current.

  As shown in FIG. 18A, the duty of the PWM signal output from the control unit 220 to the gate terminals of the switching elements 214a to 214f is not in the range of 0% to X% of the dead zone, that is, larger than X%. In this case, even when the time until the gate voltage exceeds the predetermined threshold voltage TH is taken into consideration, as shown in FIG. 18C, the time during which the switching elements 214a to 214f are turned on and the current flows is as follows. Secured.

  However, as shown in FIG. 19 (a), when the duty of the PWM signal output from the control unit 220 to the switching elements 214a to 214f is 0% to X% of the dead zone, it is shown in FIG. 19 (b). As described above, the PWM signal output from the control unit 220 changes from the high level to the low level before the gate voltage exceeds the predetermined threshold voltage TH, so that the switching elements 214a to 214f. Cannot be turned on and no current can flow. For this reason, the switching elements 214a to 214f have a dead zone that does not turn on when the duty of the PWM signal input to the control terminal approaches zero.

In step 3010 and step 3011, as a method in which the duty correction unit 322 corrects the second applied duty DB and the third applied duty DC, for example, as shown in FIG. that of the PWM signal, the adjustment period duty _{D 2} is less than 0, i.e., in the range of setting the duty Dt is less than Dmin / 2 (second predetermined value), the adjustment period duty _{D 2} is of the switching element 214a~214f in order to not be included in the scope of the -X [%] ~0 [%] is a dead zone, corrects the adjustment period duty _{D 2} to X [%] correction adjustment period duty _{D 20} with reduced. Then, in accordance with such correction, the main period duty D ₁ is corrected to a corrected main period duty D ₁₀ that is increased by X [%], and thereby the corrected main period duty D ₁₀ and the correction adjustment period duty D ₂₀ are changed. The averaged duty Dav averaged is adjusted to be the set duty Dt.

Further, the correction main periodic duty _{D 10,} the main period duty _{D 1,} according to the setting duty Dt increases from Dmin / 2 to (Dmin + x) / 2, the same change the adjustment period duty _{D 2} rate of change with respect to setting the duty Dt Increase in rate.

According to the correction, because as shown in FIG. 20 (b), the output duty of the switching element, the output main cycle duty D ₁₁ is not affected by the dead zone of the switching elements 214a-214f, the correction main cycle The output adjustment cycle duty D ₂₁ does not change with respect to the duty D ₁₀ , and the correction adjustment cycle duty D ₂₀ is included in the range of −X [%] to X [%] in which the correction adjustment cycle duty D ₂₀ is the dead zone of the switching elements 214 a to 214 f. because it is corrected so as not to be unchanged from correction adjustment period duty D ₂₀ in the range of less than Dmin / 2 by the preset duty cycle Dt. For this reason, as shown in FIG. 20C, the output average duty of the switching element linearly changes with respect to the set duty Dt in the same manner as the average duty Dav in the range where the set duty Dt is less than Dmin / 2. The output average duty and the set duty Dt have a one-to-one relationship.

Further, as shown in FIG. 20 (b), among the output duty of the switching elements 214a-214f, output adjustment period duty _{D 21} is in the range of from Dmin / 2 of (Dmin + X) / 2 by the preset duty cycle Dt, the switching element is fixed to 0 under the influence of the dead zone having the 214a-214f, although reduced from the adjustment period duty D _2, according to the correction range setting duty Dt is Dmin / 2 or more, the adjustment period duty D ₂ a decrease increase correction to the correction main cycle duty D _10, the average duty Dav the output main periodic duty D ₁₁ and output adjustment period duty D ₂₁ averaged is set to be set duty Dt, switching The average output duty of the elements 214a to 214f is set as shown in FIG. In the range where the duty Dt is Dmin / 2 or more, linearly changes with respect to similarly set the duty Dt and the average duty Dav, the output average duty and setting the duty Dt is one-to-one relationship.

In other words In other words the correction of FIG. 20 (a), in short, the adjustment period duty _{D 2} is corrected to adjust the period duty _{D 20} the adjustment period duty _{D 2} so that they are not included in the dead zone of the switching element 214a~214f together, depending on the correction, the average duty Dav of the main period duty D ₁ and the adjustment period duty D ₂ by averaging becomes linear relationship with respect to the set duty Dt (directly proportional) manner, the main period duty D ₁ correcting the correction main cycle duty _{D 10} a. Then, in some settings duty Dt, also the adjustment period duty _{D 2} is included in the dead zone of the switching elements 214a-214f, such as which output adjustment period duty _{D 21} at the output duty of the switching elements 214a-214f is predict whether a value in advance, the output main periodic duty D ₁₁ and output adjustment period duty D ₂₁ are averaged, the average output duty of the switching element 214a~214f becomes a linear relationship with respect to the set duty Dt (directly proportional) manner to correct the main cycle duty D ₁ to the correction main cycle duty D _10.

In step 3010 and step 3011, another method for the duty correction unit 322 to correct the second applied duty DB and the third applied duty DC is, for example, from the control unit 220 as shown in FIG. in PWM signal output, to be such adjustment period duty _{D 2} is not included in the range of -X [%] ~0 [%] is a dead zone of the switching element 214a-214f, setting the duty Dt (Dmin + X) / 2 or less scope, the adjustment period duty _{D 2,} 2-fold i.e. 2X [%] of the X [%] is corrected to correction adjustment period duty _{D 20} with reduced. Then, in accordance with such correction, the main cycle duty D ₁ is corrected to a corrected main cycle duty D ₁₀ increased by 2X [%] in a range where the set duty Dt is (Dmin + X) / 2 or less, thereby , average duty Dav obtained by averaging the correction main periodic duty D ₁₀ and a correction adjustment period duty D ₂₀ is set to be set duty Dt.

In other words the correction of another representation of FIG. 21 (a), the short, adjustment period duty _{D 2} is corrected to adjust the period duty _{D 20} the adjustment period duty _{D 2} so that they are not included in the dead zone of the switching element 214a~214f together, depending on the correction, the average duty Dav of the main period duty D ₁ and the adjustment period duty D ₂ by averaging becomes linear relationship with respect to the set duty Dt (directly proportional) manner, the main period duty D ₁ correcting the correction main cycle duty _{D 10} a. The main period duty D ₁ is only corrected in accordance with the correction of the adjustment period duty D _2.

According to the correction, because as shown in FIG. 21 (b), the output duty of the switching element, the output main cycle duty D ₁₁ is not affected by the dead zone of the switching elements 214a-214f, the correction main cycle The output adjustment cycle duty D ₂₁ does not change with respect to the duty D ₁₀ , and the correction adjustment cycle duty D ₂₀ is included in the range of −X [%] to X [%] in which the correction adjustment cycle duty D ₂₀ is the dead zone of the switching elements 214 a to 214 f. because it is corrected so as not to be unchanged from correction adjustment period duty D _20. For this reason, as shown in FIG. 21 (c), the output average duty of the switching elements 214a to 214f changes linearly with respect to the set duty Dt similarly to the average duty Dav, and the output average duty and the set duty Dt are 1 It becomes a one-to-one relationship.

When correction of the PWM signal output from the control unit 220 is not necessary, for example, in the range where the set duty Dt is (Dmin + X) / 2 to Dmin in FIGS. 20 (a) and 21 (a), the duty correction is performed. part 322 transmits, for PWM signal transmitted from the main cycle duty setting unit 318 and the adjustment cycle duty setting section 320, the gate signal switching unit 306 without correcting the primary cycle duty D ₁ and adjustment period duty D ₂ any To do.

  In step 3102, the non-energized phase voltage selection unit 316 detects the pulse induced voltage of the non-energized phase in the energized mode when executing this step. Specifically, the W-phase voltage Vw is detected in the energization modes M1 and M4, the V-phase voltage Vv is detected in the energization modes M2 and M5, and the U-phase voltage is detected in the energization modes M3 and M6. The voltage Vu is detected.

  Immediately after switching the energization mode, a commutation current is generated, 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 energization mode switching can be prevented from being used for determining the switching timing from the first time to the set number of times. The set times can be variably set according to the actual rotational speed of the brushless motor 100 and the current (motor load) that actually flows through the brushless motor 100, and the actual rotational speed is high and the current that actually flows is high. The set times can be set to a large value.

In step 3013, it is determined whether or not the execution condition for the low speed sensorless control is satisfied.
Specifically, the determination is made based on whether or not the actual rotational speed of the brushless motor 100 is higher than a set rotational speed that is a selection criterion for performing either the low speed sensorless control or the high speed sensorless control. The set rotational speed is the minimum value of the actual rotational speed at which switching determination can be performed using the speed electromotive force as a trigger, and is determined and stored in advance through experiments and simulations. As the set rotation speed, for example, a first set rotation speed for determining the shift to the low-speed sensorless control and a second set rotation speed (> first set rotation speed) for determining the stop of the low-speed sensorless control are set. It is preferable to suppress the switching of the sensorless control from being repeated in a short time.

  If it is determined in step 3013 that the low-speed sensorless control is performed, in other words, if the actual rotational speed of the brushless motor 100 is less than the set rotational speed, the process proceeds to step 3014, where the comparison unit 310 When the pulse induced voltage of the non-energized phase from the energized phase voltage selection unit 316 is compared with the threshold value from the voltage threshold value switching unit 312, and it is determined that the pulse induced voltage of the non-energized phase crosses the threshold value, the energization mode When it is determined that it is the switching timing, the process proceeds to step 3015, where the energization mode determination unit 308 determines the next energization mode and switches the energization mode.

  On the other hand, when it is determined in step 3013 that the low-speed sensorless control is not performed, in other words, when the actual rotational speed of the brushless motor 100 is higher than the set speed, the process proceeds to step 3016 and the pulse of the non-energized phase is performed. High-speed sensorless control is performed in which the time point at which it is determined that the induced voltage has further rotated by 30 deg from the time point when the induced voltage crosses the zero level is detected as the switching timing to the next energization mode.

  Specifically, 30 deg is converted into time based on the motor rotation speed at that time, and when the time corresponding to 30 deg has elapsed from the time of zero crossing, the timing for switching to the next energization mode is determined, and the process proceeds to step 3015. Then, switch to the next energization mode.

According to such a motor controller 200, a main period duty _{D 1} and adjustment period duty _{D 2,} according to the response of the switching element 214a~214f respect to the duty of the PWM signal, i.e., the switching element is not turned on by the dead zone Correction is performed in consideration of the duty range of the PWM signal. Accordingly, the output average duty of the switching element 214a~214f, in setting the duty Dt for adjusting period duty _{D 2} becomes a value near 0, by reducing the deviation from the preset duty cycle Dt, similar to the average duty Dav, set duty It changes linearly with respect to Dt, and the output average duty and the set duty Dt have a one-to-one relationship.
Therefore, even if the feedback control of the rotational speed setting duty Dt when adjusting period duty D ₂ becomes near 0, without output average duty swings significantly, the actual rotational speed of the brushless motor 100 causes hunting The possibility can be reduced.

In the above-described embodiment, the N period of the PWM signal composed of one main period and (N-1) adjustment period is set to N = 2 for convenience of explanation. , N may be an integer greater than 2, and the main cycle duty D ₁ and the adjustment cycle duties D _{2 to DN} can be corrected in the same manner as the above-described correction.

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

(B) A brushless motor control device that switches the energization mode in which the switching element applies a pulse voltage corresponding to the PWM signal to the two phases of the three-phase brushless motor based on the pulse induced voltage induced in the non-energized phase. There,
When the set duty, which is the duty of the set PWM signal, is less than a first predetermined value, the predetermined one period among a plurality of consecutive periods of the PWM signal is set as the main period for detecting the pulse induced voltage. 1 limiting means for limiting to a predetermined value;
The adjustment cycle such that an average duty obtained by averaging the duty of the main cycle and the duty of other cycle (adjustment cycle) other than the main cycle among the plurality of cycles of the PWM signal becomes the set duty. Adjusting means for adjusting the duty of
Correction means for correcting the duty of the main period or the duty of the adjustment period according to the response of the switching element to the duty of the PWM signal;
A control device for a brushless motor, comprising:

In this way, when the set duty becomes less than the lower limit duty (first predetermined value), the main cycle duty is limited to the lower limit duty so that the pulse induced voltage of the non-energized phase is not sampled within the fluctuation period. The control device for the brushless motor that sets the adjustment cycle duty smaller than the main cycle duty and adjusts the average duty obtained by averaging the main cycle duty and the adjustment cycle duty to be the set duty The main cycle duty and the adjustment cycle duty can be corrected according to the responsiveness of the element.
As a result, the deviation between the set duty and the output average duty of the switching element is reduced and the linearity of the output average duty with respect to the set duty is improved, so that hunting of the rotational speed in the rotational speed feedback control is suppressed. Can do.

(B) The brushless motor control device according to (A), wherein the correction unit corrects the duty of the main cycle based on the correction content of the duty of the adjustment cycle.
In this way, even if the adjustment cycle duty is corrected, it is possible to correct the main cycle duty so that the average duty by the average of the main cycle duty and the adjustment cycle duty becomes the set duty.

(C) The correction means corrects the duty of the main period or the duty of the adjustment period when the dead band of the PWM signal that does not turn on the switching element includes the duty of the adjustment period. The brushless motor control device according to (a) or (b).
In this way, the adjustment cycle duty is corrected so that the adjustment cycle duty is not included in the dead zone of the switching element, or the output of the switching element is output with respect to the adjustment cycle duty without correcting the adjustment cycle duty. The main cycle duty can be corrected by predicting in advance that the output adjustment cycle duty in the duty changes.

(D) The correction means corrects the adjustment cycle duty so that the dead band of the PWM signal that does not turn on the switching element does not include the duty of the adjustment cycle. The brushless motor control device described.
In this way, the output adjustment cycle duty at the output duty of the switching element can be prevented from changing with respect to the adjustment cycle duty.

(E) The control unit for the brushless motor according to (c) or (d), wherein the correction unit corrects the adjustment cycle duty by an integral multiple of a half width of the dead zone.
In this way, the adjustment cycle duty can be prevented from being included in the dead zone.

(F) The correction means corrects the duty of the adjustment cycle when the set duty is less than a second predetermined value smaller than the lower limit duty. The brushless motor control device described.
In this way, part of the duty of the adjustment period is not included in the dead zone of the switching element, so that the linearity of the output average duty of the switching element with respect to the set duty is improved.

(G) The control device for a brushless motor according to (e), wherein the second predetermined value is a duty when the duty of the other period becomes zero.
In this way, when the duty of the adjustment cycle is negative, it can be corrected so that the duty of the adjustment cycle is not included in the dead zone of the switching element.

(H) The correction means increases and corrects the duty of the main period, and decreases and corrects the duty of the adjustment period. (B) The brushless motor according to any one of (a) to (g), Control device.
In this way, the duty of the main period limited to the lower limit duty is not corrected for reduction, and the detection accuracy of the pulse induced voltage in the non-energized phase is ensured. In this way, the main cycle duty cannot be reduced and can only be increased, but by reducing the adjustment cycle duty, the average of the main cycle duty and the adjustment cycle duty is averaged. The duty can be matched with the set duty.

DESCRIPTION OF SYMBOLS 100 ... Brushless motor, 110u ... U phase, 110v ... V phase, 110w ... W phase, 120 ... Rotor, 200 ... Motor controller, 210 ... Drive circuit, 212a-212f ... Switching element, 302 ... Applied voltage calculating part, 304 ... PWM generation unit, 306 ... gate signal switching unit, 308 ... energization mode determination unit, 310 ... comparison unit, 312 ... voltage threshold switching unit, 316 ... non-energization phase voltage selection unit, 318 ... main cycle duty setting unit, 320 ... Adjustment cycle duty setting unit, 322... Duty correction unit

Claims (4)

A control device for a brushless motor that switches an energization mode in which a switching element applies a pulse voltage corresponding to a pulse width modulation signal to two phases of a three-phase brushless motor based on a pulse induced voltage induced in a non-energized phase. And
When the set duty of the pulse width modulation signal is less than a first predetermined value, a switching element connected to a predetermined one of a plurality of consecutive periods of the pulse width modulation signal and the first phase of the two phases Limiting means for limiting the duty of the predetermined one period to the first predetermined value as a period of detecting the pulse induced voltage as a period of applying the pulse width modulation signal to
An average duty obtained by averaging the duty of the predetermined one period limited to the first predetermined value and the duty of a period other than the predetermined one of the plurality of periods of the pulse width modulation signal is A duty of the other period is adjusted so as to become a set duty, and the set duty is less than the first predetermined value and the duty of the other period is equal to or greater than a second predetermined value. In this case, the pulse width modulation signal with the duty of the other period is applied to the switching element connected to the first phase, while the set duty becomes the duty of the other period less than zero. If it is less than the predetermined value, the pulse width modulation signal according to the duty of the other period is applied to the switching element connected to the second phase of the two phases, and adjusting means
When the set duty is less than the second predetermined value, when the duty of the other period is a value that becomes a dead zone in which the switching element connected to the second phase is not turned on, the duty of the other period Correction means for correcting the decrease by a first predetermined amount so as to deviate from the dead zone, and for increasing the duty of the predetermined one period by the first predetermined amount ;
A control device for a brushless motor, comprising: When the set duty is equal to or greater than the second predetermined value , the correction means is configured such that when the duty of the other period is a value that is a dead zone in which the switching element connected to the first phase is not turned on. The duty of another period is corrected to be decreased by a second predetermined amount so as to deviate from the dead zone, and the duty of the predetermined period is increased to be corrected by the second predetermined amount. The control device of the brushless motor described in 1. When the set duty is equal to or greater than the second predetermined value , the correction means is configured such that when the duty of the other period is a value that is a dead zone in which the switching element connected to the first phase is not turned on. The brushless motor control device according to claim 1 , wherein the duty of the predetermined cycle is corrected by adding the duty of the other cycle to the duty of the predetermined cycle. A control unit for a brushless motor that switches an energization mode in which a switching element applies a pulse voltage corresponding to a pulse width modulation signal to two phases of a three-phase brushless motor based on a pulse induced voltage induced in a non-energized phase.
When the set duty of the pulse width modulation signal is less than a first predetermined value, a switching element connected to a predetermined one of a plurality of consecutive periods of the pulse width modulation signal and the first phase of the two phases As a period for applying the pulse width modulation signal to the predetermined period, the duty of the predetermined period is limited to the first predetermined value as a period for detecting the pulse induced voltage,
An average duty obtained by averaging the duty of the predetermined one period limited to the first predetermined value and the duty of a period other than the predetermined one of the plurality of periods of the pulse width modulation signal, Adjust the duty of the other period to be the set duty,
When the set duty is less than the first predetermined value and the duty of the other period is equal to or greater than a second predetermined value that is equal to or greater than zero, a pulse width modulation signal with the duty of the other period is selected from the two phases. When the setting duty is applied to the switching element connected to the first phase and the set duty is less than the second predetermined value where the duty of the other period is less than zero, the pulse width modulation by the duty of the other period Applying a signal to the switching element connected to the second phase of the two phases;
When the set duty is less than the second predetermined value, when the duty of the other period is a value that becomes a dead zone in which the switching element connected to the second phase is not turned on, the duty of the other period Is reduced by a predetermined amount so as to deviate from the dead zone, and the duty of the predetermined cycle is increased by the predetermined amount.
Brushless motor control method.