JP7489173B2 - MOTOR CONTROL DEVICE, MOTOR CONTROL METHOD, AND VARIABLE VALVE TIMING CONTROL DEVICE AND VARIABLE VALVE TIMING CONTROL METHOD USING THEM - Google Patents

Description

The present invention relates to a motor control device and a motor control method, as well as a variable valve timing control device and a variable valve timing control method using these.

Improved fuel efficiency and cleaner exhaust are required for internal combustion engines installed in automobiles and other vehicles. As one method to achieve this, the electrification of engine accessories is being promoted. By electrifying parts that have previously been driven directly by the engine, it is expected that control response will improve and mechanical losses such as friction will be reduced. For example, power steering, which operates by driving a hydraulic pump with engine power, is becoming more and more electrified, and electrification of parts related to engine combustion control, such as variable valve timing devices, is also being considered.

There are various types of motors used for electrification, but DC motors are used in automobiles because they use a DC power source. Traditionally, DC commutator motors using brush commutators were mainstream, but with recent developments in power electronics, brushless DC motors are becoming more popular. Brushless DC motors detect the magnetic pole position using a rotation angle sensor such as a hall sensor or encoder, and control the voltage applied to the motor coil based on the detected rotation angle. One example of this type of motor control technology is disclosed in Patent Document 1.

Patent document 1 discloses a technology that includes a main control unit with three Hall sensors, and detects the rising edge of a V-phase signal, the rising edge of a W signal, and the falling edge of a U-phase signal, or the rising edge of a U-phase signal, the falling edge of a W signal, and the rising edge of a V-phase signal, to switch operating modes.

JP 2005-261957 A

When the valve timing of an engine is variably controlled by a motor, a cam attached to the motor's rotating shaft operates to open and close the valve. A variable valve timing control device that controls the motor controls the opening and closing timing of the valve by changing the rotation angle of the motor corresponding to the rotation angle of the engine. During engine operation, the motor is required to accelerate and decelerate in order to respond to required operations, such as fluctuations in engine torque. For this reason, depending on the conditions, the rotation direction of the motor may change from forward rotation to reverse rotation, or from reverse rotation to forward rotation. In this case, for example, when the technology described in Patent Document 1 is used for variable valve timing control, since speed information is obtained from the interval between pulse signals of the rotation angle sensor, a period occurs at the point where the rotation direction changes in which the interval between the pulse signals does not correspond to the speed. Therefore, there is a possibility that a period exists near the point where the rotation direction changes in which the speed is determined to be excessive. Since it is necessary to appropriately control the motor in a variable valve timing control device, high responsiveness is required, and the gain in the upper control system is generally set high. However, when an excessive speed such as that described above exists, the gain cannot be increased from the viewpoint of ensuring stability, and the speed calculation accuracy decreases, making it difficult to appropriately control the motor.

The object of the present invention is to provide a motor control device and a motor control method that can ensure speed calculation accuracy and appropriately control a motor even when the motor frequently switches between forward and reverse rotation, and a variable valve timing control device and a variable valve timing control method that use these.

In order to achieve the above object, as an example, the present invention provides a motor control device including: motor speed estimating means for estimating a motor speed estimated value based on a three-phase signal of a rotation angle sensor which outputs a magnetic flux direction as a digital signal for three phases; and gate signal generating means for outputting a gate signal adjusted so that a motor generates a desired torque, based on a duty ratio signal calculated based on the motor speed estimated value and a torque command value and the three-phase signal, wherein a rising edge is defined as a change of the digital signal output from the rotation angle sensor from a low level to a high level, and a falling edge is defined as a change of the digital signal output from the rotation angle sensor from a high level to a low level, and the motor speed estimating means includes first period determining means for determining a first period in which the three-phase signal output from the rotation angle sensor is output in the order of rising, falling, rising across the three phases; the motor speed estimation means comprising: second period determination means for determining a second period to be output; elapsed time calculation means operating based on an event detection signal generated when the three-phase signal changes to a rising or falling edge, and for calculating an elapsed time from a difference between a current FRC value generated by a free-running counter and a previous FRC value stored; speed calculation means for estimating the motor speed estimated value from the reciprocal of the elapsed time calculated by the elapsed time calculation means; previous speed value storage means for storing a previous value of the motor speed estimated value; and estimated speed selection means for selecting either the motor speed estimated value estimated by the speed calculation means or the previous value stored in the previous speed value storage means, wherein the estimated speed selection means selects the motor speed estimated value estimated by the speed calculation means when the output of the rotation angle sensor is in the first period or the second period, and selects the previous value when the output of the rotation angle sensor is in a period other than the first period or the second period.

The present invention also provides a motor control method comprising: estimating a motor speed estimate based on a three-phase signal of a rotation angle sensor which outputs a magnetic flux direction as a digital signal for three phases; and outputting a gate signal adjusted so that the motor generates a desired torque based on a duty ratio signal calculated based on the motor speed estimate and a torque command value and the three-phase signal ; wherein a rising edge is defined as a transition of the digital signal output from the rotation angle sensor from a low level to a high level, a falling edge is defined as a transition of the digital signal output from the rotation angle sensor from a high level to a low level, a first period is defined as a period during which the three-phase signal output from the rotation angle sensor is output in the order of rising, falling, rising across the three phases, and A period during which the three-phase signals output from the rotation angle sensor are output in the order of falling, rising, falling across all three phases is defined as a second period, and an elapsed time is calculated from the difference between a current FRC value generated by a free-running counter and a previously stored FRC value based on an event detection signal generated when the three-phase signals change to a rising or falling edge, and the motor speed estimated value is estimated from the reciprocal of the calculated elapsed time, and when the output of the rotation angle sensor is in the first period or the second period, control is performed to update the motor speed estimated value , and when the output of the rotation angle sensor is in a period other than the first period or the second period, the motor speed estimated value is held at the motor speed estimated value at the time of update.

The present invention provides a motor control device and a motor control method that can ensure speed calculation accuracy and appropriately control a motor even when the motor frequently switches between forward and reverse rotation, as well as a variable valve timing control device and a variable valve timing control method that use these.

1 is a block diagram showing a motor drive system according to a first embodiment of the present invention; 1 is a control block diagram of a motor control device 20 according to a first embodiment of the present invention. FIG. 2 is a control block diagram of a motor speed estimating means 28 according to the first embodiment of the present invention. FIG. 4 is a diagram showing an example of the operation of the motor speed estimating means 28 according to the first embodiment of the present invention. 5 is a flowchart showing the operation of a motor speed estimating means 28 according to the first embodiment of the present invention. FIG. 11 is a control block diagram of a motor speed estimating means 28 according to a second embodiment of the present invention. FIG. 11 is a diagram showing an example of the operation of a motor speed estimating means 28 according to the second embodiment of the present invention. FIG. 11 is a control block diagram of a motor speed estimating means 28 according to a third embodiment of the present invention. FIG. 11 is a diagram showing an example of the operation of a motor speed estimating means 28 according to the third embodiment of the present invention. 10 is a flowchart showing the operation of a motor speed estimating means 28 according to the third embodiment of the present invention. FIG. 13 is a diagram showing the relationship between the change phase and the direction of rotation according to a third embodiment of the present invention. FIG. 11 is a cross-sectional view of a variable valve timing control device according to a fourth embodiment of the present invention. FIG. 13 is a diagram showing the operation of the variable valve timing control device according to the fourth embodiment of the present invention. FIG. 13 is a schematic diagram of an electric power steering device according to a fifth embodiment of the present invention.

The motor control device according to the embodiment of the present invention is particularly applicable to applications that require high speed responsiveness, and targets a brushless DC motor as the motor. Main application examples envisioned are a variable valve timing control device that uses a motor to control the valve timing in an internal combustion engine, and an electric power steering device that uses a motor to assist steering operations.

In an embodiment of the present invention, a rotation angle sensor is provided that outputs a three-phase signal for detecting the rotation angle of a motor, and a first period is defined as a period in which the three-phase signal output from the rotation angle sensor is output in the order of rising, falling, rising across the three phases, and a second period is defined as a period in which the three-phase signal output from the rotation angle sensor is output in the order of falling, rising, falling across the three phases, and when the output of the rotation angle sensor is in the first period or the second period, the rotation speed output of the motor is updated. In this embodiment, by configuring as described above, it is possible to select as the rotation speed a case in which the rotation direction of the motor changes and a case in which the rotation speed output calculation calculated by detecting the rotation angle sensor pulse signal interval is accurate for the period until the motor rotation becomes stable. This makes it possible to eliminate the influence of speed calculation errors in the area where forward and reverse rotation change and in the area of unstable speed due to insufficient shaft rigidity, etc.

In an embodiment of the present invention, a rotation angle sensor is provided that outputs a three-phase signal for detecting the rotation angle of the motor, and a period from when only a specific phase of the three-phase signals output from the rotation angle sensor changes at least twice to when a signal change of a phase other than the specific phase is detected is defined as a third period, and when the output of the rotation angle sensor is in the third period, the rotation speed output of the motor is held at the previous rotation speed output, and the rotation speed output of the motor is updated at the end of the third period.

In an embodiment of the present invention, a rotation angle sensor is provided that outputs a three-phase signal for detecting the rotation angle of a motor, and a period from when only a specific phase of the three-phase signals output from the rotation angle sensor changes at least twice to when a signal change of a phase other than the specific phase is detected is defined as a third period, and when the output of the rotation angle sensor is in the third period, the rotation speed output of the motor is set to 0, and the rotation speed output of the motor is updated at the end of the third period.

Furthermore, in an embodiment of the present invention, in a variable valve timing control including an intake cam and an exhaust cam that open and close the intake valve and the exhaust valve, an intake side camshaft and an exhaust side camshaft that are connected to the intake cam and the exhaust cam, respectively, and an intake side electric valve timing control motor and an exhaust side electric valve timing control motor that rotate and drive the intake side camshaft and the exhaust side camshaft, the intake side electric valve timing control motor and the exhaust side electric valve timing control motor are controlled by the motor control described in the above embodiment.

In an embodiment of the present invention, by adjusting the valve timing of the engine using a motor driven by the above-mentioned motor control device, it is possible to ensure speed calculation accuracy and appropriately control the motor even when forward and reverse rotation is frequently switched, contributing to reduced fuel consumption and cleaner exhaust emissions.

The following describes an example that embodies the above embodiment.

Figure 1 is a block diagram showing a motor drive system according to a first embodiment of the present invention. In this embodiment, an inverter for driving a three-phase motor is used as the power conversion device, and the motor 10 to be controlled is a brushless DC motor. Torque generated by the motor 10 is transmitted to the motor shaft 11. The motor 10 determines the timing of applying voltage to each winding using a rotation angle sensor 12. An absolute encoder or resolver can be used as the rotation angle sensor 12, but this figure uses a Hall IC as an example for explanation. The Hall IC outputs the magnetic flux direction as a digital signal. The wiring connected to the motor 10 is three-phase wiring 13, and an AC voltage is applied to the wiring 13 from a power conversion device 14. The power conversion device 14 converts the DC voltage into an AC voltage by turning on and off a switching element 15, and creates the AC voltage to be applied to the wiring 13.

The current detector 16 (DC current detector) measures the current flowing into or out of the power conversion device 14. Typically, a shunt resistor is inserted between the ground point and the negative connection terminal of the switching element 15, and the current is detected by measuring the voltage across the shunt resistor. The switching element 15 is turned on/off by a gate voltage 18 created by a gate driver 17. The gate driver 17 amplifies a gate signal 19 that determines the on/off timing of the switching element 15, and converts it into a voltage and current that enables the switching element 15 to operate.

The motor control device 20 receives a command signal 21 from a higher-level control system such as an electronic control unit (ECU), and creates a gate signal 19 for operating the motor 10 so as to follow this command signal 21. The motor control device 20 uses a rotation angle sensor signal 22 and a DC current signal 23 as other inputs. The rotation angle sensor signal 22 is the output of the rotation angle sensor 12, and three phase signals, U phase, V phase, and W phase, are output. In this embodiment, these three phase signals are defined as a three-phase signal. The DC current signal 23 is the output of the current detector 16.

Next, the configuration of the motor control device 20, which is part of the configuration of the motor drive system, will be described. FIG. 2 is a control block diagram of the motor control device 20 according to the first embodiment of the present invention. In this embodiment, the command signal 21 received by the motor control device 20 is a torque command.

The command signal 21 is input to the compensation means 24. The compensation means 24 receives the command signal 21 and the torque estimate 25, performs control so that the deviation between the command signal 21 and the torque estimate 25 is reduced, and outputs a torque command signal 26. Specifically, a means such as PID control is used. The torque estimation means 27 estimates the torque estimate 25 from the DC current signal 23. In the brushless DC motor that is the subject of this embodiment, the generated torque is approximately proportional to the DC current, so the torque estimate 25 can be estimated from the DC current signal 23.

The rotation angle sensor signal 22 is input to the motor speed estimation means 28, which outputs a motor speed estimate 29. The motor speed estimate 29 is used for various purposes, such as constructing a speed control system, correcting back electromotive force, and improving the accuracy of the rotation angle, but for simplicity, only the back electromotive force estimation means 30 is shown here. In a brushless DC motor (motor 10), as the rotation speed increases, the voltage that can be used to generate torque due to the electromotive force inside the motor decreases. The back electromotive force estimation means 30 calculates the back electromotive force estimate 31. If no advance angle control is performed, the back electromotive force is simply proportional to the motor rotation speed.

The torque command signal 26 and the back electromotive force estimated value 31 are sent to the phase voltage conversion means 32, which calculates the phase voltage to be applied to each phase of the motor 10. The power conversion device 14 changes the phase voltage by changing the switching duty ratio, so here it outputs a duty ratio signal 33. For example, when the duty ratio is 1, a DC voltage (VDC) is applied as the phase voltage, when the duty ratio is 0, 0 is applied, and when the duty ratio is 0.5, half the DC voltage (VDC/2) is applied. The duty ratio signal 33, torque direction signal 34, and rotation angle sensor signal 22 created in this way are input to the gate signal creation means 35, which outputs the gate signal 19 adjusted so that the motor 10 generates the desired torque.

Next, we will explain the configuration of the motor speed estimation means 28, which is part of the configuration of the motor control device 20. Figure 3 is a control block diagram of the motor speed estimation means 28 according to the first embodiment of the present invention.

The rotation angle sensor signal 22 input to the motor speed estimation means 28 is input to the change event detection means 41, the first period determination means 42, and the second period determination means 43. The change event detection means 41 generates an event detection signal 44 when the rotation angle sensor signal 22 changes. Typically, the event detection signal 44 is often implemented in a microcomputer as an interrupt activation. When the event detection signal 44 is generated, the first period determination means 42 and the second period determination means 43 store the state of the rotation angle sensor signal 22 and compare it with a preset change pattern.

The rotation angle sensor signal 22 has two levels: high level and low level. When the rotation angle sensor signal 22 changes from low level to high level, it is called a rising edge, and when the rotation angle sensor signal 22 changes from high level to low level, it is called a falling edge.

In this embodiment, the first period is a pattern in which the rotation angle sensor signal 22 (three-phase signal) output from the rotation angle sensor 12 detects a rise, fall, and rise change in sequence, and the change extends across all phases (three phases) of the U phase, V phase, and W phase.

The second period is a pattern in which the rotation angle sensor signal 22 (three-phase signal) output from the rotation angle sensor 12 detects changes of falling, rising, and falling in that order, and the changes extend across all phases (three phases) of the U, V, and W phases. The timing diagram of the first and second periods will be described later in FIG. 4.

The outputs of the first period determination means 42 and the second period determination means 43 are sent to the logical sum means 45, which performs the speed calculation described below when either the first period or the second period is satisfied.

The event detection signal 44 also operates the elapsed time calculation means 46. The elapsed time calculation means 46 inputs the FRC current value 48 generated by the FRC (free running counter) 47, and calculates the difference between the current FRC value 48 and the previous FRC value 50 recorded in the previous FRC value storage means 49. This is equivalent to the time interval of the event detection signal 44. After calculating the difference, the FRC current value 48 is sent to the previous FRC value storage means 49, and the previous FRC value 50 is updated. The speed calculation means 51 estimates the motor speed by calculating the inverse of the time interval calculated by the elapsed time calculation means 46. Since the speed calculation means 51 cannot always calculate the motor speed, it is provided with an estimated speed selection means 52. For example, when the motor speed is 0 (zero), the event detection signal 44 is not generated, so in such a case, it is necessary to output some motor speed estimate value by a different method. In this embodiment, when the motor speed cannot be calculated, the estimated speed selection means 52 selects whether to use the previous speed value or to forcibly set the estimated motor speed to 0 (zero).

In this embodiment, if the behavior of the rotation angle sensor 12 does not fall under either the first period determination means 42 or the second period determination means 43, the estimated speed selection means 52 selects the stored value of the previous speed value storage means 53 or the zero speed setting means 54 as the estimated speed 55. If the behavior of the rotation angle sensor 12 falls under either the first period determination means 42 or the second period determination means 43, the output of the speed calculation means 51 is selected as the output of the estimated speed 55.

Next, the operation of the motor speed estimating means 28 will be described with reference to Fig. 4. Fig. 4 is a diagram showing an example of the operation of the motor speed estimating means 28 according to the first embodiment of the present invention. For the sake of simplicity, the following is assumed.
The rotation angle sensor 12 is a Hall IC and outputs a digital signal.
The elapsed time calculation means 46 obtains the time when the rotation angle sensor 12 of any phase changes.
The Hall ICs are arranged with a 120 degree offset for each phase, and an event detection signal 44 is generated every 60 degrees of motor rotation.
・The motor is a three-phase, two-pole machine, and the effects of reduction gears, etc. are not taken into consideration. This makes the mechanical angle and electrical angle equal, eliminating the need for conversion.
・The motor rotation direction is defined as forward rotation clockwise and reverse rotation counterclockwise.

The phases are U, V, and W clockwise, with the U-phase Hall IC positioned 60 degrees behind the U-phase of the motor coil, the V-phase Hall IC positioned 60 degrees behind the V-phase of the motor coil, and the W-phase Hall IC positioned 60 degrees behind the W-phase of the motor coil.

In FIG. 4, 22a is a U-phase Hall IC, 22b is a V-phase Hall IC, and 22c is a W-phase Hall IC. Hall ICs 22a to 22c are arranged between the windings of motor 10 as shown in the figure. 61a, 61b, 61c, 61d, and 61e are the times when Hall ICs 22a to 22c change, and 62a, 62b, 62c, 62d, and 62e are the rotational states of motor 10 at times 61a, 61b, 61c, 61d, and 61e.

The condition for the speed calculation means 51 to be able to calculate a reliable estimated speed is when the elapsed time calculation means 46 is able to correctly obtain the time it takes for the motor 10 to rotate 60 degrees. The elapsed time calculation means 46 monitors the changes in the Hall ICs 22a-22c and looks at the time intervals between them, so when forward and reverse rotation switches, the elapsed time calculation means 46 does not measure the time it takes to rotate 60 degrees, and as a result, the speed calculation means 51 outputs a speed calculation result that differs from the actual result.

In FIG. 4, the motor 10 rotates in the forward direction until time 61a. Here, the forward direction is defined as clockwise. After the output of the W-phase Hall IC 22c changes at time 61a, the motor 10 rotates in the reverse direction due to the influence of an external force or the like from time 61a to time 61b, and the output of the W-phase Hall IC 22c changes again at time 61b. The motor 10 returns to forward rotation from time 61b to time 61c, and the output of the W-phase Hall IC 22c changes at time 61c. Thereafter, the forward rotation continues at times 61d and 61e. During periods 61c, 61d, and 61e during which the forward rotation continues, the output rise of the W-phase Hall IC 22c, the output fall of the V-phase Hall IC 22b, and the output rise of the U-phase Hall IC 22a are observed. In other words, by observing the rising and falling patterns of the output of the Hall ICs 22a to 22c, it is possible to determine whether the motor is rotating stably in the forward or reverse direction, which serves as a criterion for determining whether to operate the speed calculation means 51.

The time interval 63 indicated by the arrow is calculated by the elapsed time calculation means 46. Also, the speed calculation selection time 64 indicated by a triangle is the result calculated by the speed calculation means 51 and selected by the estimated speed selection means 52.

Here, the pattern in which the outputs of the Hall ICs 22a to 22c change in the order of rising, falling, and rising, and the outputs of all of the Hall ICs 22a to 22c change, is defined as the first period. Also, the pattern in which the outputs of the Hall ICs 22a to 22c change in the order of falling, rising, and falling, and the outputs of all of the Hall ICs 22a to 22c change, is defined as the second period.

In FIG. 4, the arrow indicated by number 65 is the first period, and the arrow indicated by number 66 is the second period. When the brushless DC motor rotates normally in the forward or reverse direction, the first period 65 or the second period 66 is observed as long as the Hall ICs 22a to 22c are operating normally and continuously. When the output of the rotation angle sensor signal 22 is in the first period 65 or the second period 66, the result of the speed calculation means 51 is adopted, and the rotation speed output of the motor 10 is updated.

In FIG. 4, the speed calculation selection time 64 is displayed when the first period 65 or the second period 66 is detected. This makes it possible to determine not to use the results of the speed calculation means 51 obtained from the time interval from time 61a to time 61b and the time interval from time 61b to time 61c, during which the time it takes for the motor 10 to rotate 60 degrees cannot be obtained. Then, when the output of the rotation angle sensor signal 22 is outside the first period 65 or the second period 66, the rotation speed output of the motor 10 is maintained at the rotation speed output at the time of update.

In addition, in FIG. 4, the result of the speed calculation means 51 obtained from the time interval from time 61c to time 61d is not used. This is because if an unexpected reverse rotation occurs during forward rotation, it is expected that a large external force is being applied, and there is a concern that the output accuracy of the elapsed time calculation means 46 will deteriorate in the time interval from time 61c to time 61d due to the effects of shaft torsion and backlash during that period. In this embodiment, the output of the speed calculation means 51 is not used even in the period from time 61c to time 61d, so it is particularly suitable for applications where it is difficult to ensure rigidity.

In addition, this is suitable for a control system with high-gain characteristics to ensure high responsiveness. In the case of a high-gain control system, if the speed estimation error is large, it is determined that the deviation from the command is also large, and a large torque is generated to try to follow it. As a result, power consumption increases. Also, it is difficult to ensure stability, but this embodiment can easily solve the problems associated with high-gain control systems.

Next, the operation of the motor speed estimation means 28 will be described. Figure 5 is a flowchart showing the operation of the motor speed estimation means 28 according to the first embodiment of the present invention.

In FIG. 5, the flow chart is started by detecting the event detection signal 44. S101 is a process for acquiring the counter, and the current value of the FRC 47 is stored in the variable cnt. S102 is a process for acquiring the output of the Hall ICs 22a to 22c. The acquired output of the Hall ICs 22a to 22c is used to identify the phase in which a change has occurred by the change phase identification process S103. Then, the change phase information is written to the variable phs by the change phase writing process S104. The variable phs may be an integer value (U phase = 1, V phase = 2, W phase = 3, etc.) or a character (U phase = 'u', V phase = 'V', W phase = 'W', etc.) as long as the phase can be identified. The counter acquisition process S101, the output acquisition process S102 of the Hall ICs 22a to 22c, the change phase identification process S103, and the change phase writing process S104 are executed in parallel using the event detection signal 44 as a trigger.

The previous counter value acquisition process S105 reads out the counter information acquired by the previous event detection signal 44 as the variable cnt_z. S106 is a time interval acquisition process, which calculates the difference between the variables cnt and cnt_z and stores it in the variable t60. t60 means the time required for the motor 10 to rotate an electrical angle of 60 degrees. Since the FRC 47 is represented by a limited number of bits, it is cleared to 0 at regular intervals. Therefore, there are cases where cnt_z>cnt depending on the timing of cnt acquisition.

Time interval determination process S107 checks whether variable t60 is positive or negative to determine whether cnt_z>cnt. If variable t60 is negative, time interval correction process S108 adds a preset constant CMAX+1. This obtains the correct time interval. Note that CMAX is the maximum value of FRC. For example, if FRC is 16 bits, CMAX is 65535. If variable t60 is positive, variable t60 is used as the time interval as is.

S109 is a speed calculation process, in which the reciprocal of variable t60 is multiplied by 2π (π is the circular constant) and then divided by 6 to obtain a temporary electrical angle speed spd_tmp. Multiplying by 2π is to convert the unit system to rad/s, and dividing by 6 is to convert to the speed per rotation. S110 is a previous counter value update process, in which the acquired counter information cnt is substituted for the previous counter value cnt_z. Processes S101 to S110 are mainly performed by the elapsed time calculation means 46, previous FRC value storage means 49, and speed calculation means 51.

S111 is a phase information acquisition process, which reads the change phase phs, the previous change phase phs_z, and the change phase before last phs_z2. The variable phs is written out in the change phase write process S104. S112 is a first period determination process, which determines whether the change phase phs, the previous change phase phs_z, and the change phase before last phs_z2 correspond to the first period described above. If they do not correspond to the first period, the subsequent second period determination process S113 is performed to determine whether they correspond to the second period described above. If the determination in either S112 or S113 is Y, the tentative electrical angle speed spd_tmp calculated in the speed calculation process S109 is adopted as the electrical angle speed spd.

If it is neither the first period nor the second period, a speed comparison process S115 determines whether it is high or low speed. If the constant TH is the speed threshold, and the variable spd_tmp is greater than the speed threshold TH, the previous speed value setting process S116 sets the electrical angular velocity spd to the previous electrical angular velocity value spd_z. If the variable spd_tmp is smaller than the speed threshold TH, the zero speed setting process S117 sets the electrical angular velocity spd to 0. This electrical angular velocity spd is the estimated speed 55. Here, if the output of the rotation angle sensor is other than the first period or the second period, the rotation speed output of the motor is set to 0.

S119 is a phase information update process, in which the previous change phase phs_z is substituted for the change phase before last phs_z2, and the change phase phs is substituted for the previous change phase phs_z. S111 to S119 are processes performed by the first period determination means 42, the second period determination means 43, the logical sum means 45, the estimated speed selection means 52, the previous speed value storage means 53, and the zero speed setting means 54.

According to this embodiment, the motor rotation speed output is updated when the output of the rotation angle sensor is in the first or second period, so that the speed calculation accuracy can be ensured and the motor can be appropriately controlled even when the motor frequently switches between forward and reverse rotation.

Next, a second embodiment will be described. FIG. 6 is a control block diagram of the motor speed estimation means 28 according to the second embodiment of the present invention. The configuration of the motor control device 20 and the motor drive system is the same as that in FIG. 1, so a detailed description will be omitted.

The difference from the first embodiment shown in FIG. 3 is that a third period determination means 56 is provided instead of the first period determination means 42, the second period determination means 43, and the logical sum means 45. The third period is defined as the period from the point in time when only the signal of a specific phase of the three-phase signal has changed two or more times until a change in a phase other than the specific phase is detected.

Figure 7 is a diagram showing an example of the operation of the motor speed estimation means 28 according to the second embodiment of the present invention. In Figure 7, the third period is the period from time 61b to time 61d. Unlike Figure 4, the speed calculation selection time 64 also corresponds to time 61d. As in Figure 4, the results of the speed calculation means 51 obtained from the time intervals from time 61a to time 61b and from time 61b to time 61c, in which the time required for the motor 10 to rotate 60 degrees cannot be obtained, are not adopted. However, the results of the speed calculation means 51 obtained from the time intervals from time 61c to time 61d are adopted as the speed calculation result.

During the period between time 61c and time 61d, for example, if the rotating shaft of motor 10 has sufficient rigidity or if a high-resolution sensor is available, the speed detection error is sufficiently small. Therefore, the second embodiment can be used in the case of hardware that satisfies the above conditions.

In the second embodiment, by using the judgment based on the third period, it becomes possible to update the speed information even at time 61d, which is effective in improving responsiveness.

Next, we will explain how to calculate the speed. For simplicity, we will use the same assumptions about the rotation angle sensor 12 and motor 10 used in Figure 4.

The difference between FIG. 7 and FIG. 4 is that the execution and stop of speed calculation is determined by the presence or absence of the third period 67. From the start of the third period 67 to just before the end of the third period 67, the value stored in the previous speed value storage means 53 or the zero speed setting means 54 is selected as the estimated speed 55. If the value of the zero speed setting means 54 is selected, the rotation speed output of the motor 10 becomes 0. The speed calculation means 51 continues to operate in the third period 67, and updates the estimated speed 55 immediately after the end of the third period 67. If the third period 67 is not detected, the estimated speed 55 adopts the result of the speed calculation means 51 as usual.

Note that the flowchart in the second embodiment is omitted because it simply replaces the first period determination process S112 and the second period determination process S113 with the third period determination process in the flowchart of the first embodiment shown in FIG. 5.

According to the second embodiment, it is possible to ensure the accuracy of speed calculation and appropriately control the motor even when the motor frequently switches between forward and reverse rotation.

Next, a third embodiment will be described. Figure 8 is a control block diagram of the motor speed estimation means 28 according to the third embodiment of the present invention. The configuration of the motor control device 20 and the motor drive system is the same as that of Figure 1, so a detailed description will be omitted. Also, for the sake of simplicity, the following description will be given assuming that the rotation angle sensor 12 is a Hall IC.

The U-phase change event generating means 71a, V-phase change event generating means 71b, and W-phase change event generating means 71c, which serve as phase change event generating means for each phase, monitor changes in the rotation angle signal of each layer and notify the presence or absence of a change.

In FIG. 8, the output of the U-phase Hall IC 22a among the input three-phase rotation angle sensor signals 22 is input to the U-phase change event generating means 71a. The U-phase change event generating means 71a constantly monitors the output of the Hall IC 22a, and generates an event detection signal 44 when a change is detected. When implemented in an embedded microcomputer, this is generally realized by generating an interrupt due to a change in the digital I/O input. If the microcomputer has sufficient processing capabilities, it may be configured to constantly monitor by polling. The same is true for the V-phase and W-phase, and there is a V-phase change event generating means 71b that monitors the output of the Hall IC 22b, and a W-phase change event generating means 71c that monitors the output of the Hall IC 22c. In addition, the V-phase change event generating means 71b generates a V-phase event detection signal 44b, and the W-phase change event generating means 71c generates a W-phase event detection signal 44c.

The three-phase rotation angle sensor signal 22 is input to the U-phase update permission means 72a, which determines whether the U-phase change event is to be used or ignored. When implemented in an embedded microcomputer, this is generally realized as a flag. In this case, the U-phase update permission means 72a operates, for example, as follows.
If the phase that changed immediately before was the V or W phase, the U phase update permission flag is set (permitted).
・If the phase that changed immediately before was the U phase, clear the U phase update permission flag (not permitted).
In addition, in realizing this, it is also possible to use a method based on state transitions, for example, without relying on flags.

The same is true for the V and W phases, and there is a V phase update permission means 72b and a W phase update permission means 72c.

The U-phase event detection signal 44a operates the U-phase change time storage means 73a. When the U-phase update permission means 72a permits an update, the U-phase change time storage means 73a stores the FRC current value 48 (current time) obtained from the free running counter 47 as the time when the U-phase changed. When the U-phase update permission means 72a prohibits an update, the U-phase change time storage means 73a does not operate. The same is true for the V-phase and W-phase, and the means has a V-phase change time storage means 73b and a W-phase change time storage means 73c.

The U-phase change time storage means 73a, V-phase change time storage means 73b, and W-phase change time storage means 73c (phase change time storage means) store the change time of the rotation angle signal for each phase. After the U-phase change time storage means 73a, V-phase change time storage means 73b, and W-phase change time storage means 73c (phase change time storage means) finish their respective processes, they are transmitted to the elapsed time calculation means 46 and start operating.

The elapsed time calculation means 46 inputs the U phase change time stored in the U phase change time storage means 73a, the V phase change time stored in the V phase change time storage means 73b, and the W phase change time stored in the W phase change time storage means 73c, and calculates the difference between the two most recent change times. The obtained difference in change times is sent to the speed calculation means 51. The speed calculation means 51 calculates the speed from the difference in the change times of the rotation angle signals of each phase output from the phase change time storage means of each phase in the three phases (the difference between the two most recent change times). Since the difference between the two most recent change times represents the occurrence interval of the event detection signal 44, the speed information can be obtained by calculating the reciprocal.

Figure 9 is a diagram showing an example of the operation of the motor speed estimation means 28 according to the third embodiment of the present invention. The difference between Figure 9 and Figure 7 in the second embodiment is that there is a W-phase update prohibited section 68.

At time 61a, a change in the output of the W-phase Hall IC 22c is observed. Since the previous change in the rotation angle sensor signal 22 was U-phase, the W-phase update permission means 72c is in the permission state at this point, and the W-phase change time storage means 73c operates. At the same time, the elapsed time calculation means 46 and the speed calculation means 51 operate. After the elapsed time calculation means 46 and the speed calculation means 51 operate, the W-phase update permission means 72c clears the W-phase update permission flag, and the state becomes one in which changes in the W phase are not permitted.

At time 61b, when the motor 10 rotates in the reverse direction due to an external force or the like, the output of the W-phase Hall IC 22c changes again. However, at this point, the W-phase update permission means 72c does not permit the operation of the W-phase change time storage means 73c, so the change time information at time 61b is skipped. In other words, if the same phase changes continuously before the other phases change, the change time information is ignored. At time 61c, the motor 10 returns to forward rotation, but at this time too, the W-phase update permission means 72c does not permit the operation of the W-phase change time storage means 73c, so the change time information at time 61c is skipped. In other words, the phase change time storage means updates the rotation speed output of the motor 10 when the phase change event generation means detects a change in the rotation angle signal in one phase and then detects a change in the rotation angle signal in the other phase.

At time 61d, a change in the V-phase Hall IC 22b is observed. At this point, the V-phase update permission means 72c permits the operation of the V-phase change time storage means 73b, and the V-phase change time storage means 73b operates. At the same time, the elapsed time calculation means 46 and the speed calculation means 51 operate. After the elapsed time calculation means 46 and the speed calculation means 51 operate, the V-phase update permission means 72b clears the W-phase update permission flag, and the state does not permit a change in the V-phase. At the same time, the W-phase update permission means 72c sets the W-phase update permission flag, and the state permits a change in the W-phase.

In the case of the embodiment shown in FIG. 9, just like the embodiment shown in FIG. 7, it is possible to update the motor rotation speed output at time 61d, which is effective in improving responsiveness.

Figure 10 is a flowchart showing the operation of the motor speed estimation means 28 according to the third embodiment of the present invention. Note that the elapsed time calculation means 46 and the speed calculation means 51 are omitted because their processing is exactly the same as that from S106 onwards in the flowchart shown in Figure 5.

In FIG. 10, the U-phase Hall IC 22a, V-phase Hall IC 22b, and W-phase Hall IC 22c are monitored simultaneously in parallel, so after processing begins, the processing flow is branched into three. From the left, the processing is related to the U-phase, the V-phase, and the W-phase, and since the processing is similar for each phase, only the processing flow on the far left (ending in 'a') will be explained.

S121a is a monitoring process for the U-phase Hall IC 22a, and monitors changes in the U-phase Hall IC 22a by means of an interrupt or the like. If there is no change, monitoring continues, and if there is a change, the process proceeds to the U-phase update determination process S122a. If the U-phase update permission means 72a permits the update, the process proceeds to the next process, and if it prohibits it, the process returns to process S121a again. The update determination method of the U-phase update permission means 72a has been described in the explanation of Figure 8, so a description will be omitted here.

S123a is a pulse direction acquisition process that acquires the direction of change of the U-phase Hall IC 22a. Here, the variable name representing the pulse direction is written as "pls_dir". S101a is a counter acquisition process, and S105a is a previous counter value acquisition process, and the same processes as those in the flowchart shown in FIG. 5 are performed.

S124a is an information update process, which updates the variables in the U-phase change time storage means 73a. Here, the current change phase is written as "phs" and the previous change phase is written as "phs_z". Also, the previous value of the variable "pls_dir" explained in process S123a is written as "pls_dir_z". The variables updated here are provided to determine the rotation direction of the motor 10.

The motor control device 20 in this embodiment is intended for applications in which the motor frequently rotates back and forth, and variables are used because it is often important to determine the direction of rotation in the upper control system. By combining these variables, the direction of rotation of the motor can be easily determined, for example, as shown in the table in Figure 11.

Figure 11 is a diagram showing the relationship between the change phase and the direction of rotation in the third embodiment of the present invention. Note that the variables "phs" and "phs_z" that represent the change phase are of character type, and the variables "pls_dir" and "pls_dir_z" that represent the pulse direction are written with the rising edge as +1 and the falling edge as -1.

In FIG. 10, process S125a represents the process of the U-phase change time storage means 73a. Process S126 is a joining process, in which when the process related to the U phase, the process related to the V phase, or the process related to the W phase is completed, the branched process flows are joined and the process moves to the subsequent stage. Note that, because motor control is designed with care so that each branch is not performed simultaneously, all considerations regarding memory conflict processing between each branch flow and interrupt priority order are omitted in the description.

According to the third embodiment, if the same phase changes consecutively before another phase changes, the change time information is ignored, so that the speed calculation accuracy can be ensured and the motor can be appropriately controlled even when the motor frequently switches between forward and reverse rotation.

The above describes an embodiment of the motor control device 20 according to the present invention. The present invention is a motor control device that uses the time interval of the rotation angle sensor 12 to detect the speed, and other embodiments are possible. For example, the rotation angle sensor 12 is not limited to a Hall IC, and can be applied to, for example, an encoder pulse signal in the same manner. A typical incremental encoder pulse has two phases, A and B, but the W phase can be omitted in the embodiments shown in Figures 6 and 8. In addition, in the explanation of each embodiment, for the sake of simplicity, the speed is calculated using the time interval measured every 60 degrees of motor rotation angle, but the present invention can be applied even if another speed detection method is used. For example, six time interval information from the rising edge of the U phase to the next rising edge, the falling edge of the U phase to the next falling edge, the rising edge of the V phase to the next rising edge, the falling edge of the V phase to the next falling edge, the rising edge of the W phase to the next rising edge, and the falling edge of the W phase to the next falling edge may be used. This is a method of measuring the time required for 360 rotations every 60 degrees of motor rotation angle, but this can also be applied by changing the speed calculation means 51.

When the time interval of the output of the rotation angle sensor signal 22 is used to detect the speed, the speed calculation means 51 cannot be implemented strictly when the motor is completely stopped, because the information of the rotation angle sensor signal 22 cannot be obtained. In this case, for example, if no information is obtained for a certain period of time, it is advisable to use a countermeasure such as setting the speed to 0 (zero).

According to this embodiment, at the moment when forward and reverse rotations are switched, the situation where the time interval of the rotation angle sensor signal 22 does not correspond to the rotation speed is detected and dealt with, so that the speed calculation error can be reduced even in a situation where forward and reverse rotations are switched. Therefore, this embodiment is particularly suitable for applications where forward and reverse rotations are repeated.

Next, a fourth embodiment of the present invention will be described. In the fourth embodiment, an example will be described in which the motor control device described in the first to third embodiments is applied to a variable valve timing control device. Figure 12 is a cross-sectional view of a variable valve timing control device according to the fourth embodiment of the present invention.

The engine 201 is equipped with an intake side electric valve timing control device 10a and an exhaust side electric valve timing control device 10b. The engine crankshaft 202 is connected to a piston in a cylinder, and converts the reciprocating motion of the piston into rotational motion.

The intake cam 204a and exhaust cam 204b are connected to the intake camshaft 203a and exhaust camshaft 203b, respectively.

The intake side electric valve timing control device 10a has an intake side electric valve timing control motor attached to the engine 201, and an intake side phase changer attached to the intake side camshaft 203a. The intake side phase changer transmits the rotational force of the crankshaft 202 by a timing chain or timing belt, and has a speed reduction mechanism (not shown) that can reduce the rotation of the intake side electric valve timing control motor to change the rotational phase of the intake side camshaft 203a and the crankshaft 202.

The exhaust side electric valve timing control device 10b has an exhaust side electric valve timing control motor attached to the engine 201, and an exhaust side phase changer attached to the exhaust side camshaft 203b. Like the intake side phase changer, the exhaust side phase changer is also designed to transmit the rotational force of the crankshaft 202 by a timing chain or timing belt, and has a speed reduction mechanism (not shown) that can reduce the rotation of the exhaust side electric valve timing control motor to change the rotational phase of the exhaust side camshaft 203b and the crankshaft 202.

The intake cam 204a opens the intake valve 206a by pressing the intake valve stem end 205a. When the intake cam 204a rotates to a position where it does not press the intake valve stem end 205a, the intake valve 206a is closed by the intake valve spring 207a. Similarly, on the exhaust side, the exhaust cam 204b opens the exhaust valve 206b by pressing the exhaust valve stem end 205b. When the exhaust cam 204b rotates to a position where it does not press the exhaust valve stem end 205b, the exhaust valve 206b is closed by the exhaust valve spring 207b.

The variable valve timing control device shown in FIG. 12 is a system called a rotationally synchronized type, in which the intake camshaft 203a and the exhaust camshaft 203b are normally controlled to rotate in synchronization with the crankshaft 202. In the case of a four-stroke internal combustion engine, a "synchronized state" is defined as a state in which the camshaft rotates once for every two rotations of the crankshaft, and the valve opening start angle and valve opening end angle are always the same crankshaft angle.

In such a variable valve timing control device, the intake timing can be advanced by increasing the rotation speed of the intake side electric valve timing control motor from a synchronized state, and then returning to the synchronized state once the desired valve opening angle is reached. This is called "advancing." The intake timing can also be delayed by decreasing the rotation speed of the intake side electric valve timing control motor from a synchronized state, and then returning to the synchronized state once the desired valve opening angle is reached. This is called "retarding." The exhaust valve can be controlled in exactly the same way.

Next, the operation of the variable valve timing control device will be described with reference to FIG. 13. FIG. 13 is a diagram showing the operation of the variable valve timing control device according to the fourth embodiment of the present invention.

Here, an example is shown of the operation from the maximum retard angle (re-retard angle) that the engine allows, through the maximum advance angle (re-advance angle), and back to the re-retard angle. The horizontal axis is time. 211 is a graph of the engine speed, 212 is a graph of the valve phase angle, and 213 is a graph of the motor speed. Note that in this embodiment, the engine speed is constant, and the valve phase angle 212 is set to 0 degrees when it is the camshaft angle relative to the crankshaft angle in a normal operating state. Also, since the intake side and exhaust side are completely similar, no distinction will be made between intake and exhaust hereafter. In this embodiment, at least one of the intake and exhaust sides is provided with a motor that opens and closes the valve.

When changing from re-retard to re-advance, the motor speed rises once at t1 and then falls to the synchronous speed at t2. This allows the valve phase angle to be changed back to advance. From this state, the motor speed is lowered at t3 and then raised to the synchronous speed again at t4, allowing the valve phase angle to be changed back to retard. When changing from advance to retard, the motor speed is lowered from t3 to t4, but at this time, depending on the synchronous speed determined from the engine speed and the required response up to the re-retard, a situation may occur in which the motor rotation speed switches from forward to reverse. Conventional motor speed calculation methods have large calculation errors when switching from forward to reverse. In variable valve timing control devices, the upper control system is often high gain to ensure high responsiveness, and as a result, calculation errors can significantly deteriorate control performance.

In the fourth embodiment, therefore, by controlling the intake side electric valve timing control device 10a and the exhaust side electric valve timing control device 10b using the motor control device described in the first to third embodiments, it is possible to reduce calculation errors at the point where forward rotation is switched to reverse rotation, thereby providing a variable valve timing control device with improved responsiveness.

Next, a fifth embodiment of the present invention will be described. In the fifth embodiment, an example will be described in which the motor control device described in the first to third embodiments is applied to an electric power steering device. FIG. 14 is a schematic diagram of an electric power steering device according to the fifth embodiment of the present invention. The electric power steering device assists steering operation with the driving force of a motor.

A steering shaft 222 is connected to the steering wheel 221. A motor 10, which serves as the driving source of the electric power steering device, is connected to a motor shaft 11. The motor shaft 11 is connected to the steering shaft 222 by a power synthesis means 223, and the power of the motor 10 is synthesized to the steering shaft 222 by the power synthesis means 223. The steering shaft 222 with the synthesized power is coupled to a steering gear mechanism 224. The steering gear mechanism 224 is attached to a knuckle arm 225 and changes the direction of the wheels 226.

Electric power steering devices are constantly exposed to resistance from the road surface. In addition, the driver repeatedly makes small adjustments to the steering wheel to compensate for road resistance, causing the motor 10 to repeatedly rotate forward and backward. By applying the motor control device described in the first to third embodiments to an electric power steering device, it is possible to achieve the effect of realizing control that reduces the torque that rebounds to the driver, even when the steering wheel 221 rotates in the direction opposite to the direction intended by the driver during off-road driving (the so-called "kicked" state). Furthermore, when electric airplanes become widespread, a similar effect can be expected for electric rudder control for aircraft.

10...motor, 10a...intake side electric valve timing control device, 10b...exhaust side electric valve timing control device, 11...motor shaft, 12...rotation angle sensor, 13...wiring, 14...power conversion device, 15...switching element, 16...current detector, 17...gate driver, 18...gate voltage, 19...gate signal, 20...motor control device, 21...command signal, 22...rotation angle sensor signal, 23...DC current signal, 24...compensation means, 25...torque estimation value, 26...torque command signal, 27...torque estimation means, 28...motor speed estimation means, 29...motor speed estimation value, 30... Back electromotive force estimation means, 31...back electromotive force estimated value, 32...phase voltage conversion means, 33...duty ratio signal, 34...torque direction signal, 35...gate signal creation means, 41...change event detection means, 42...first period determination means, 43...second period determination means, 44...event detection signal, 44a...U-phase event detection signal, 44b...V-phase event detection signal, 44c...W-phase event detection signal, 45...logical OR means, 46...elapsed time calculation means, 47...free running counter, 48...FRC current value, 49...previous value storage means, 50...previous value, 51...speed calculation means, 52...estimated speed selection means , 53...previous speed value storage means, 54...zero speed setting means, 55...estimated speed, 56...third period determination means, 61a, 61b, 61c, 61d, 61e...time, 63...time interval, 64...speed calculation selection time, 65...first period, 66...second period, 67...third period, 68...phase update prohibited section, 71a...U-phase change event generation means, 71b...V-phase change event generation means, 71c...W-phase change event generation means, 72a...U-phase update permission means, 72b...V-phase update permission means, 72c...W-phase update permission means, 73a...U-phase change time storage means, 73b...V-phase change time storage means, 73c... W-phase change time storage means, 201...engine, 202...crankshaft, 203a...intake side camshaft, 203b...exhaust side camshaft, 204a...intake cam, 204b...exhaust cam, 205a...intake valve stem end, 205b...exhaust valve stem end, 206a...intake valve, 206b...exhaust valve, 207a...intake valve spring, 207b...exhaust valve spring, 212...valve phase angle, 221...steering wheel, 222...steering shaft, 223...power synthesis means, 224...steering gear mechanism, 225...knuckle arm, 226...wheel

Claims (8)

A motor control device comprising: a motor speed estimating means for estimating a motor speed estimated value based on a three-phase signal of a rotation angle sensor which outputs a magnetic flux direction as a digital signal for three phases; and a gate signal generating means for outputting a gate signal adjusted so that a motor generates a desired torque, based on a duty ratio signal calculated based on the motor speed estimated value and a torque command value and the three-phase signal,
a rising edge is defined as a transition of the digital signal output from the rotation angle sensor from a low level to a high level, and a falling edge is defined as a transition of the digital signal output from the rotation angle sensor from a high level to a low level,
The motor speed estimation means
a first period determination means for determining a first period during which the three-phase signal output from the rotation angle sensor is output in the order of rising, falling, and rising across three phases;
a second period determination means for determining a second period during which the three-phase signal output from the rotation angle sensor is output in the order of falling, rising, and falling across three phases;
an elapsed time calculation means which operates based on an event detection signal generated when the three-phase signal changes to a rising or falling edge, and calculates an elapsed time from the difference between the current FRC value generated by the free-running counter and the previous FRC value stored;
a speed calculation means for estimating the motor speed estimate value from the reciprocal of the elapsed time calculated by the elapsed time calculation means;
a previous speed value storage means for storing a previous value of the motor speed estimate;
an estimated speed selection means for selecting either the motor speed estimated value estimated by the speed calculation means or the previous value stored in the previous speed value storage means,
the estimated speed selection means selects the motor speed estimated value estimated by the speed calculation means when the output of the rotation angle sensor is in the first period or the second period, and selects the previous value when the output of the rotation angle sensor is in a period other than the first period or the second period.
Equipped with A motor control device comprising: a motor speed estimating means for estimating a motor speed estimated value based on a three-phase signal of a rotation angle sensor which outputs a magnetic flux direction as a digital signal for three phases; and a gate signal generating means for outputting a gate signal adjusted so that a motor generates a desired torque, based on a duty ratio signal calculated based on the motor speed estimated value and a torque command value and the three-phase signal,
a rising edge is defined as a transition of the digital signal output from the rotation angle sensor from a low level to a high level, and a falling edge is defined as a transition of the digital signal output from the rotation angle sensor from a high level to a low level,
The motor speed estimation means
a third period determination means for determining a third period from a point in time when only a signal of a specific phase among the three-phase signals output from the rotation angle sensor has changed two or more times to a point in time when a signal change of a phase other than the specific phase is detected;
an elapsed time calculation means which operates based on an event detection signal generated when the three-phase signal changes to a rising or falling edge, and calculates an elapsed time from the difference between the current FRC value generated by the free-running counter and the previous FRC value stored;
a speed calculation means for estimating the motor speed estimate value from the reciprocal of the elapsed time calculated by the elapsed time calculation means;
a previous speed value storage means for storing a previous value of the motor speed estimate;
an estimated speed selection means for selecting either the motor speed estimated value estimated by the speed calculation means or the previous value stored in the previous speed value storage means,
the estimated speed selection means selects the previous value when the output of the rotation angle sensor is in the third period, and selects the motor speed estimated value estimated by the speed calculation means at the end of the third period. A motor control device comprising: a motor speed estimating means for estimating a motor speed estimated value based on a three-phase signal of a rotation angle sensor which outputs a magnetic flux direction as a digital signal for three phases; and a gate signal generating means for outputting a gate signal adjusted so that a motor generates a desired torque, based on a duty ratio signal calculated based on the motor speed estimated value and a torque command value and the three-phase signal,
a rising edge is defined as a transition of the digital signal output from the rotation angle sensor from a low level to a high level, and a falling edge is defined as a transition of the digital signal output from the rotation angle sensor from a high level to a low level,
The motor speed estimation means
a third period determination means for determining a third period from a point in time when only a signal of a specific phase among the three-phase signals output from the rotation angle sensor has changed two or more times to a point in time when a signal change of a phase other than the specific phase is detected;
an elapsed time calculation means which operates based on an event detection signal generated when the three-phase signal changes to a rising or falling edge, and calculates an elapsed time from the difference between the current FRC value generated by the free-running counter and the previous FRC value stored;
a speed calculation means for estimating the motor speed estimate value from the reciprocal of the elapsed time calculated by the elapsed time calculation means;
a zero speed setting means for setting the estimated speed of the motor to zero;
an estimated speed selection means for selecting either the motor speed estimated value estimated by the speed calculation means or the estimated motor speed of 0 set by the zero speed setting means,
said estimated speed selection means sets the estimated motor speed to 0 when the output of the rotation angle sensor is within the third period, and selects the motor speed estimated value estimated by the speed calculation means at the end of the third period. A variable valve timing control device including an intake cam and an exhaust cam for opening and closing an intake valve and an exhaust valve, an intake camshaft and an exhaust camshaft connected to the intake cam and the exhaust cam, respectively, and an intake side electric valve timing control motor and an exhaust side electric valve timing control motor for driving and rotating the intake side camshaft and the exhaust side camshaft,
4. A variable valve timing control device, wherein the intake side electric valve timing control motor and the exhaust side electric valve timing control motor are controlled by a motor control device according to claim 1. A motor control method comprising the steps of: estimating a motor speed estimate based on a three-phase signal of a rotation angle sensor which outputs a magnetic flux direction as a digital signal for three phases; and outputting a gate signal adjusted so that the motor generates a desired torque based on a duty ratio signal calculated based on the motor speed estimate and a torque command value and the three-phase signal, the method comprising the steps of:
a rising edge is defined as a transition of the digital signal output from the rotation angle sensor from a low level to a high level, and a falling edge is defined as a transition of the digital signal output from the rotation angle sensor from a high level to a low level,
a first period is a period during which the three-phase signal output from the rotation angle sensor is output in the order of rising, falling, and rising across three phases;
a second period is a period during which the three-phase signal output from the rotation angle sensor is output in the order of falling, rising, and falling across the three phases;
Based on an event detection signal generated when the three-phase signals change to a rising or falling edge, an elapsed time is calculated from the difference between the current FRC value generated by a free-running counter and the previous FRC value stored in the memory, and the motor speed estimate value is estimated from the reciprocal of the calculated elapsed time.
a motor control method comprising: controlling to update the motor speed estimate value when the output of the rotation angle sensor is in the first period or the second period; and holding the motor speed estimate value at the motor speed estimate value at the time of update when the output of the rotation angle sensor is in a period other than the first period or the second period. A motor control method comprising the steps of: estimating a motor speed estimate based on a three-phase signal of a rotation angle sensor which outputs a magnetic flux direction as a digital signal for three phases; and outputting a gate signal adjusted so that the motor generates a desired torque based on a duty ratio signal calculated based on the motor speed estimate and a torque command value and the three-phase signal, the method comprising the steps of:
a rising edge is defined as a transition of the digital signal output from the rotation angle sensor from a low level to a high level, and a falling edge is defined as a transition of the digital signal output from the rotation angle sensor from a high level to a low level,
a third period is a period from when only a signal of a specific phase among the three-phase signals output from the rotation angle sensor changes two or more times to when a signal change of a phase other than the specific phase is detected;
Based on an event detection signal generated when the three-phase signals change to a rising or falling edge, an elapsed time is calculated from the difference between the current FRC value generated by a free-running counter and the previous FRC value stored in the memory, and the motor speed estimate value is estimated from the reciprocal of the calculated elapsed time.
a motor speed estimation value that is updated when the output of the rotation angle sensor is within the third period and that is indicative of a current speed of the motor; A motor control method comprising the steps of: estimating a motor speed estimate based on a three-phase signal of a rotation angle sensor which outputs a magnetic flux direction as a digital signal for three phases; and outputting a gate signal adjusted so that the motor generates a desired torque based on a duty ratio signal calculated based on the motor speed estimate and a torque command value and the three-phase signal, the method comprising the steps of:
a rising edge is defined as a transition of the digital signal output from the rotation angle sensor from a low level to a high level, and a falling edge is defined as a transition of the digital signal output from the rotation angle sensor from a high level to a low level,
a third period is a period from when only a signal of a specific phase among the three-phase signals output from the rotation angle sensor changes two or more times to when a signal change of a phase other than the specific phase is detected;
Based on an event detection signal generated when the three-phase signals change to a rising or falling edge, an elapsed time is calculated from the difference between the current FRC value generated by a free-running counter and the previous FRC value stored in the memory, and the motor speed estimate value is estimated from the reciprocal of the calculated elapsed time.
a motor speed estimation value being updated when the output of the rotation angle sensor is within the third period, the estimated motor speed being set to 0, and the motor speed estimation value being updated when the third period ends. A variable valve timing control method comprising an intake cam and an exhaust cam for opening and closing an intake valve and an exhaust valve, an intake camshaft and an exhaust camshaft connected to the intake cam and the exhaust cam, respectively, and an intake side electric valve timing control motor and an exhaust side electric valve timing control motor for driving and rotating the intake side camshaft and the exhaust side camshaft,
8. A variable valve timing control method, wherein the intake side electric valve timing control motor and the exhaust side electric valve timing control motor are controlled by a motor control method according to any one of claims 5 to 7 .

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