Motor control device and control method therefor

Abstract

To provide a motor control device in which even if a motor is subjected to driving control which leads to great change of the rotational speed at the start time of the motor, driving control in which energization switching is performed at a timing different from a timing of detection of a magnetic pole position in a rotor can be adopted.SOLUTION: In the present invention, a motor control device 3 that performs driving control based on maximum current control at the start time of a motor, and then transitions to normal-time driving control, includes a control unit 32 that switches energization in a U-phase, a V-phase, and a W-phase. The control unit 32 performs first control which is motor driving initial time control for performing the switching at a first timing of detection of a magnetic pole position in a rotor, and second control which is normal time control for performing the switching at a second timing different from the first timing. The control unit 32 performs transition from the first control to the second control at a prescribed timing when the operation state becomes close to that of a normal time.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a motor control device and a control method thereof. [Background technology]

[0002] 2. Description of the Related Art Conventionally, in an electric oil pump device, a brushless motor may be used as a motor for driving the pump. When driving a brushless motor, a rotation angle sensor is often used, and the rotation angle sensor may be, for example, a Hall IC or a TMR (Tunnel Magneto-Resistance Effect) sensor.

[0003] When detecting the rotation angle using a TMR sensor, the magnetic force of a TMR sensor magnet attached to the motor shaft is detected by the TMR sensor, and the rotation angle of the motor is calculated from the detected magnetic force.

[0004] However, if the relative position between the TMR sensor magnet attached to the motor shaft and the motor magnet is uncertain, the TMR sensor can determine the motor's rotation angle as a relative position, but cannot determine the rotation angle as an absolute position.

[0005] Therefore, the TMR sensor needs to perform zero-point detection to identify the initial position of the motor. Therefore, Patent Document 1 discloses a motor control device and a control method thereof that performs angle correction of a rotation angle sensor based on the induced voltage of a brushless motor, thereby eliminating the need for additional configuration to perform angle correction of the rotation angle sensor. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2023-32765 Summary of the Invention [Problem to be solved by the invention]

[0007] In Patent Document 1, the motor is controlled by a 120° energization method in which energization is switched every 120° electrical angle in response to the timing of detection of the magnetic pole position of the motor. However, motor performance can be improved by using advance angle control, which switches the energization at a position that is phase-advanced from the timing of detecting the motor's magnetic pole position, or by using wide-angle energization, which switches the energization at an energization angle greater than 120°.

[0008] On the other hand, in the motor used in the electric oil pump, it is necessary to ensure torque when the motor is started. For this reason, in the motor used in the electric oil pump, drive control is performed using maximum current control when the motor is started, and after the motor rotation speed reaches almost the maximum rotation speed, the rotation speed changes significantly toward the steady-state rotation speed.

[0009] Furthermore, advance angle control and wide-angle energization predict the appropriate timing for energization switching based on the timing of detection of the motor's magnetic pole position and the motor's rotation speed, and perform energization switching at a timing different from the timing of detection of the rotor's magnetic pole position, so there is a problem that they are difficult to apply when the rotation speed changes significantly, as mentioned above.

[0010] The present invention has been made in consideration of the above circumstances, and aims to provide a motor control device and control method that can apply drive control that switches current flow at a timing different from the timing at which the rotor's magnetic pole position is detected, even to a motor that performs drive control in which the rotation speed changes significantly when the motor is started. [Means for solving the problem]

[0011] In order to achieve the above object, the present invention is realized by the following configuration. The motor control device of the present invention is a motor control device that performs drive control using maximum current control when the motor is started, and then transitions to drive control during steady state operation.The control device has a control unit that switches the current supply to the U phase, V phase, and W phase, and the control unit performs a first control at the beginning of motor drive, in which the switching is performed at a first timing when the magnetic pole position of the rotor is detected, and a second control during steady state operation, in which the switching is performed at a second timing different from the first timing, and the control unit transitions from the first control to the second control at a predetermined timing when the operating state during steady state operation is approached.

[0012] The motor control method of the present invention is a motor control method that performs drive control using maximum current control when the motor is started, and then transitions to drive control during steady state operation, performing a first control at the beginning of motor drive that switches current supply to the U phase, V phase, and W phase at a first timing when the magnetic pole position of the rotor is detected, and a second control during steady state that performs the switching at a second timing different from the first timing, and transitioning from the first control to the second control at a predetermined timing when the motor approaches the steady state operating state. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a motor control device and a control method that can apply drive control that switches current flow at a timing different from the timing at which the rotor's magnetic pole position is detected, even to a motor that performs drive control that causes the rotation speed to change significantly when the motor is started. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a diagram showing the configuration of an electric oil pump equipped with a motor control device of a first embodiment according to the present invention. [Figure 2] FIG. 3 is a diagram for explaining a first control of the first embodiment according to the present invention. [Figure 3] FIG. 2 is a diagram for explaining complementary PWM control in the first embodiment according to the present invention. [Figure 4] FIG. 4 is a diagram for explaining a second control of the first embodiment according to the present invention. [Figure 5] 3A and 3B are diagrams for explaining a control state in which the first control and the second control are combined and performed by the control unit of the first embodiment according to the present invention. [Figure 6] FIG. 10 is a diagram for explaining a second control of the second embodiment according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a mode for carrying out the present invention (hereinafter referred to as an "embodiment") will be described in detail with reference to the accompanying drawings. It should be noted that the same elements are denoted by the same numbers or symbols throughout the description of the embodiments.

[0016] (First embodiment) FIG. 1 is a diagram showing the configuration of an electric oil pump equipped with a control device 3 for a motor 1 according to a first embodiment of the present invention. The electric oil pump can be suitably used as a pump for hydraulic equipment such as a continuously variable transmission mounted on a vehicle, for example, by pumping up oil stored in an oil pan, applying hydraulic pressure, and supplying the oil.

[0017] The electric oil pump includes a motor 1, a pump 2 driven by the motor 1, and a control device 3 that controls the driving of the motor 1.

[0018] (Motor 1) The motor 1 is a brushless motor, and in this embodiment, includes a rotor R having a permanent magnet with a pair of N and S poles, and a stator that is arranged on the outer periphery of the rotor R at a distance from the rotor R and has a U-phase winding CU, a V-phase winding CV, and a W-phase winding CW.

[0019] The motor 1 also includes three hall sensors (a U-phase hall sensor HU, a V-phase hall sensor HV, and a W-phase hall sensor HW) that detect the magnetic pole position of the rotor R.

[0020] Specifically, the U-phase Hall sensor HU is provided between the U-phase winding CU and the V-phase winding CV (at approximately the middle position) when viewed in the circumferential direction.

[0021] In addition, the V-phase Hall sensor HV is provided between the V-phase winding CV and the W-phase winding CW (at approximately the midpoint) when viewed in the circumferential direction, and similarly, the W-phase Hall sensor HW is provided between the W-phase winding CW and the U-phase winding CU (at approximately the midpoint) when viewed in the circumferential direction.

[0022] In this embodiment, a case has been described in which a Hall sensor is used as a sensor for detecting the magnetic pole position of the rotor R, but the sensor for detecting the magnetic pole position of the rotor R does not need to be limited to a Hall sensor. For example, the sensor that detects the magnetic pole position of the rotor R may be an absolute angle sensor such as a resolver. In this case, the magnetic pole position of the rotor R can be detected more accurately, and the efficiency and controllability of the motor 1 can be further improved. That is, the magnetic pole position of the rotor R may be detected by the output signal of an absolute angle sensor provided in the motor 1, instead of the Hall sensor.

[0023] (Pump 2) The pump 2 includes a rotary drive unit (not shown) that rotates to pump out oil, and the rotary drive unit is connected to an output shaft (not shown) that is rotated by the rotor R of the motor 1. The pump 2 itself may have the same configuration as a general oil pump, and details thereof will be omitted.

[0024] (Control device 3) The control device 3 includes a three-phase bridge circuit (also referred to as an inverter section) having two switching elements (U-phase upper element U-FET1 and U-phase lower element U-FET2) for the U-phase winding CU, two switching elements (V-phase upper element V-FET1 and V-phase lower element V-FET2) for the V-phase winding CV, and two switching elements (W-phase upper element W-FET1 and W-phase lower element W-FET2) for the W-phase winding CW.

[0025] In this embodiment, field effect transistors (FETs) are used as switching elements for the U-phase winding CU, the V-phase winding CV, and the W-phase winding CW.

[0026] The U-phase upper element U-FET1 is a switching element on the high side of the U-phase, and the U-phase lower element U-FET2 is a switching element on the low side of the U-phase. Similarly, the V-phase upper element V-FET1 and the W-phase upper element W-FET1 are switching elements on the high side of the V phase and the W phase, respectively, and the V-phase lower element V-FET2 and the W-phase lower element W-FET2 are switching elements on the low side of the V phase and the W phase, respectively.

[0027] The control device 3 also includes a control unit 32 (e.g., a microcomputer) that switches the energization of the U phase, V phase, and W phase based on output signals from three Hall sensors that detect the magnetic pole position of the rotor R, and a drive circuit 31 (e.g., a gate driver IC) that drives the switching elements of the three-phase bridge circuit in accordance with control signals from the control unit 32 that switch the energization of the U phase, V phase, and W phase. The control unit 32 has a storage unit (not shown) and also has a timer function.

[0028] The control unit 32 then performs a first control at the beginning of motor drive, in which the energization of the U phase, V phase, and W phase is switched at a first timing when the magnetic pole position of the rotor R is detected, and a second control during steady state, in which the energization of the U phase, V phase, and W phase is switched at a second timing different from the first timing when transitioning from the first control.

[0029] A detailed explanation of the combination of the first control and the second control will be given later, but first, the basic parts of the first control and then the second control will be explained individually. As will be explained later, the first control is a control for switching the energization at the beginning of motor driving, and the second control is a control for switching the energization during steady state.

[0030] (First control) FIG. 2 is a diagram for explaining the first control of the first embodiment according to the present invention, showing the Hall sensor output and the switching state of the switching element. In FIG. 2, the electrical angle is shown at the top as 0° to 360°. The electrical angle is expressed as 360°, which is one cycle of switching the current supply to the U, V, and W phases. In this embodiment, a 2-pole, 3-slot motor is used, so the mechanical angle (360° of one physical rotation) and the electrical angle of 360° are the same.

[0031] Also, the U-phase FET energization (U-FET1, U-FET2) in FIG. 2 indicates the energization state of the switching elements corresponding to the U-phase, that is, the ON / OFF states of the two switching elements (U-phase upper element U-FET1 and U-phase lower element U-FET2) for the U-phase winding CU described above.

[0032] Similarly, the V-phase FET conduction (V-FET1, V-FET2) and the W-phase FET conduction (W-FET1, W-FET2) in FIG. 2 respectively indicate the ON / OFF states of two switching elements (V-phase upper element V-FET1 and V-phase lower element V-FET2) for the V-phase winding CV and two switching elements (W-phase upper element W-FET1 and W-phase lower element W-FET2) for the W-phase winding CW.

[0033] Furthermore, the U-phase Hall sensor HU output, the V-phase Hall sensor HV output, and the W-phase Hall sensor HW output indicate the ranges in which the outputs of the U-phase Hall sensor HU, the V-phase Hall sensor HV, and the W-phase Hall sensor HW are High or Low relative to the electrical angle.

[0034] The HU, HV, and HW sensor outputs at the bottom show that the combination of outputs from the U-phase Hall sensor HU, the V-phase Hall sensor HV, and the W-phase Hall sensor HW changes every 60° of electrical angle, and the Hall sensor outputs can be used to distinguish between 60° of electrical angle. As can be seen from FIG. 2, one of the switching elements is switched ON and OFF every 60° of electrical angle.

[0035] For example, at an electrical angle of 0°, the V-phase Hall sensor HV output remains low and unchanged, and similarly, the W-phase Hall sensor HW output remains high and unchanged, but the U-phase Hall sensor HU output changes from low to high. In this case, the U-phase upper stage device U-FET1 is switched from OFF (see 330° to 360° on the right) to ON. Similarly, at this timing of 0° electrical angle, the W-phase upper stage device W-FET1 is switched from ON to OFF.

[0036] Similarly, at an electrical angle of 60° when the W-phase Hall sensor HW output changes from high to low, the V-phase lower-stage element V-FET2 switches from ON to OFF, and the W-phase lower-stage element W-FET2 switches from OFF to ON.

[0037] As can be seen from FIG. 2, the switching elements are turned on and off at a first timing every 60° electrical angle when the output of any of the U-phase Hall sensor HU, V-phase Hall sensor HV, and W-phase Hall sensor HW changes from high to low or from low to high, resulting in switching of the current supply to the U-phase, V-phase, and W-phase.

[0038] In other words, the switching elements are turned on and off at the first timings of electrical angles 0°, 60°, 120°, 180°, 240°, and 300° at which the magnetic pole position of the rotor R is detected, resulting in switching of the current supply to the U phase, V phase, and W phase.

[0039] In this way, the magnetic pole position of the rotor R is detected every 60° electrical angle by the output signals of the U-phase Hall sensor HU, the V-phase Hall sensor HV, and the W-phase Hall sensor HW provided on the motor 1, and the control unit 32 performs a first control at the beginning of motor drive, which switches the current supply to the U-phase, V-phase, and W-phase at the first timing when the magnetic pole position of the rotor R is detected.

[0040] In this embodiment, PWM (Pulse Width Modulation) control is performed during the period when the high-side switching element is ON. Specifically, in the case of the U-phase upper stage element U-FET1, in the section from electrical angle 0° to 120° indicated as ON in FIG. 2, the U-phase upper stage element U-FET1 is controlled to be repeatedly turned ON and OFF. PWM control is also performed in the V-phase upper stage element V-FET1 in the electrical angle range of 120° to 240°, and in the W-phase upper stage element W-FET1 in the electrical angle range of 240° to 360°.

[0041] In this way, by performing PWM control, the rotation speed of the motor 1 can be controlled by adjusting the ON-OFF duty ratio (the ratio of the ON waveform width to one ON-OFF cycle).

[0042] Furthermore, during the period when the high-side switching element is ON, the low-side switching element is also controlled to be repeatedly turned ON and OFF. In other words, the section in which the high-side switching element is ON is under complementary PWM control.

[0043] FIG. 3 is a diagram for explaining complementary PWM control according to the first embodiment of the present invention, and specifically shows the operation of two switching elements (U-phase upper element U-FET1 and U-phase lower element U-FET2) for the U-phase winding CU in the electrical angle range from 0° to 120° when the U-phase upper element U-FET1 is ON.

[0044] In Figure 3, the number of switching operations in the electrical angle range from 0° to 120° is shown to be quite small so that the switching state can be seen and understood, but in reality, high-speed switching is performed much more frequently than the number of switching operations shown in Figure 3.

[0045] In Figure 3, the electrical angle is shown on the upper side, with the ON-OFF switching waveform on the upper side corresponding to the U-phase upper element U-FET1 and the ON-OFF switching waveform on the lower side corresponding to the U-phase lower element U-FET2.

[0046] As shown in FIG. 3, the PWM control is complementary in that the waveform of the U-phase upper element U-FET1 is inverted with respect to the waveform of the U-phase lower element U-FET2.

[0047] However, in order to prevent the U-phase upper element U-FET1 and the U-phase lower element U-FET2 from turning ON at the same time, more specifically, the U-phase lower element U-FET2 turns ON with a delay of dead time DT after the U-phase upper element U-FET1 turns OFF, and the U-phase lower element U-FET2 turns OFF earlier by the dead time DT than the U-phase upper element U-FET1 turns ON.

[0048] Note that complementary PWM control with such a dead time DT set can be achieved, for example, by an on-delay in which the rising edges of the waveforms of the U-phase upper element U-FET1 and the U-phase lower element U-FET2 are delayed by the dead time DT, while the falling edges are left unchanged.

[0049] (Second control) Next, the second control will be described. FIG. 4 is a diagram for explaining the second control of the first embodiment according to the present invention, and in the first embodiment, a case where advance angle control is performed as the second control is shown.

[0050] In FIG. 4, in order to make it easier to understand the control states of the switching elements, the switching states of the first control switching elements described above with reference to FIG. 2 are shown at the top.

[0051] In addition, to make the drawing easier to understand, the Hall sensor outputs shown in Figure 2 are omitted, but as explained in the first control, the magnetic pole position of the rotor R is detected at the first timing of electrical angles of 0°, 60°, 120°, 180°, 240°, and 300° using the output signals of the U-phase Hall sensor HU, the V-phase Hall sensor HV, and the W-phase Hall sensor HW.

[0052] In Figure 4, the control state of the switching elements for the second control is shown on the lower side, but as mentioned above, in this embodiment, the second control is an advance angle control that switches the current supply to the U phase, V phase, and W phase at a second timing different from the first timing at which the magnetic pole position of the rotor R is detected. For ease of understanding, in FIG. 4, dotted arrows indicate how the switching elements of the U-phase upper stage element U-FET1 are controlled.

[0053] As shown by the short dotted arrow in FIG. 4, at an electrical angle of 0°, the magnetic pole position of the rotor R is first detected, and based on this first timing, the next timing for turning on the U-phase upper-stage element U-FET1 is set to a second timing that appropriately advances the phase toward the advance angle side.

[0054] For example, this second timing is calculated by calculating the time from the first timing at which an electrical angle of 0° is detected to the electrical angle position (hereinafter simply referred to as the position) at which the phase is appropriately advanced from the rotation speed of motor 1 to the advance angle side.

[0055] Then, using the timer function of the control unit 32, the next U-phase upper stage device U-FET1 is turned ON at a position where the time determined from the first timing at which the electrical angle of 0° is detected has elapsed.

[0056] That is, based on the magnetic pole position of the rotor R one cycle before, the ON of the U-phase upper stage device U-FET1 in the next cycle is controlled to the advance side.

[0057] The same applies to turning off the U-phase upper stage element U-FET1. As shown by the long dotted arrow in FIG. 4, the timer function of the control unit 32 is used to turn off the U-phase upper stage element U-FET1 next time when the time has elapsed from the first timing at which an electrical angle of 120° is detected to a position where the phase has been appropriately advanced toward the advance angle side.

[0058] As for the remaining switching elements, although they are not indicated by dotted arrows, as shown in FIG. 4, the ON / OFF timing of each of the switching elements is set at a position where the phase is appropriately advanced toward the advance angle side, similar to the U-phase upper-stage element U-FET1.

[0059] In this way, by controlling the phase to advance toward the advance angle side, the phase shift between the phase induced voltage and the phase current that occurs when switching the energization at the first timing when the magnetic pole position of the rotor R is detected can be canceled, and high torque can be obtained.

[0060] The appropriate amount of phase advance to the advance angle side varies depending on the characteristics, rotation speed, load torque (current value), etc. of the motor 1. Therefore, for example, taking these factors into consideration, it is possible to determine in advance whether the appropriate amount of phase advance to the advance angle side is appropriate, and store this in the control unit 32.

[0061] Also in the second control, similarly to the first control, complementary PWM control with a dead time DT is performed in the section in which the high-side switching element is ON.

[0062] As described above, the second control predicts the second timing for switching the appropriate switching elements based on the first timing at which the magnetic pole position of the rotor R is detected and the rotation speed of the motor 1. Therefore, there is a problem in that it is difficult to predict the second timing when the rotation speed changes drastically.

[0063] As mentioned above, this situation is particularly evident in motors such as electric oil pumps, which require torque to be secured when the motor is started, and in which drive control is performed using maximum current control, and the motor rotation speed changes significantly toward the steady-state rotation speed after reaching nearly the maximum rotation speed.

[0064] However, the control unit 32 of this embodiment can solve this problem by performing a first control at the beginning of motor drive, which switches the current supply to the U phase, V phase, and W phase at a first timing when the magnetic pole position of the rotor R described above is detected, and a second control during steady state, which switches the current supply to the U phase, V phase, and W phase at a second timing different from the first timing.

[0065] (Control combining the first and second controls) Next, the switching of energization by the control unit 32 that combines the first control and the second control will be described. FIG. 5 is a diagram for explaining a control state in which the first control and the second control are combined and performed by the control unit 32 of the first embodiment according to the present invention.

[0066] In FIG. 5, the vertical axis indicates the rotation speed of the motor 1, and the horizontal axis indicates the time elapsed since the motor started. During section A immediately after the motor is started, drive control is performed using maximum current control, and the rotation speed of the motor 1 increases suddenly.

[0067] Furthermore, since it is not possible to guarantee that the rotation speed of the motor 1 will increase linearly in section A, even if the actual rotation speed, which is the actual rotation speed at the first timing (also called current time N) when the magnetic pole position of the rotor R is detected, is known, it is difficult to predict how far the rotor R will rotate at the next time (time N+1) based on that information.

[0068] Therefore, as shown in the upper part of Figure 5, the control corresponding to section A is performed using the first control, in section A where the rotation speed of motor 1 changes drastically, the control unit 32 switches the current supply to the U phase, V phase, and W phase at the first timing when the magnetic pole position of rotor R is detected, rather than making a prediction.

[0069] Then, at the point when the rotation of the motor 1 is ensured (at the boundary between section A and section B), control is started to match the actual rotation speed of the motor 1 with the command rotation speed. For example, as mentioned above, the duty ratio of the PWM control is adjusted so that the actual rotation speed becomes the command rotation speed.

[0070] The time period from the start of the motor until which section A is to be set may be determined in advance.

[0071] Specifically, first, the time required for the motor 1 to rotate properly is calculated in advance. The previously determined time (hereinafter also referred to as the maximum current time) is stored in the control unit 32, and the period from when the motor is started until the maximum current time has elapsed is set as section A.

[0072] After the motor is started, once the maximum current time has elapsed, control is performed in section B to match the actual rotation speed, which is the actual rotation speed of the motor 1, with the command rotation speed. That is, after the maximum current time (also called maximum current control time) has elapsed, control shifts to command rotation speed control.

[0073] Then, in section B, control is performed to adjust the actual rotation speed of motor 1 from the high rotation speed after maximum current control to the lower rotation speed of the command rotation speed, but because the rotation speed of motor 1 decreases rapidly, a linear decrease in rotation speed cannot be expected. For this reason, as explained above, in section B, it is difficult to predict how far rotor R will have rotated from the current time N to the next time N+1.

[0074] Therefore, even in section B where the rotation speed of motor 1 changes drastically, as shown in the upper part of Figure 5, the control corresponding to section B is performed using the first control, and instead of making a prediction, the control unit 32 switches the current supply to the U phase, V phase, and W phase at the first timing when the magnetic pole position of rotor R is detected.

[0075] In this way, during the initial stage of motor drive (sections A and B) when the rotation speed of motor 1 changes drastically after the motor starts, control unit 32 performs a first control at the initial stage of motor drive, which switches the current supply to U phase, V phase, and W phase at the first timing when the magnetic pole position of rotor R is detected.

[0076] Then, at a predetermined timing (the boundary point between section B and section C) when the difference δ between the command rotation speed and the actual rotation speed of the motor 1 becomes small and approaches a steady-state operating state, the control unit 32 transitions from the first control to the second control.

[0077] The predetermined timing at which the difference δ between the instructed rotation speed and the actual rotation speed of motor 1 becomes small is short when the instructed rotation speed is high, and conversely, long when the instructed rotation speed is low.

[0078] However, the time required to reach this predetermined timing can be determined in advance in relation to the commanded rotation speed. The relationship between the time required to reach the specified timing and the specified rotation speed will vary depending on the characteristics of the motor 1, but once the target motor 1 is determined, it can be found to suit that motor 1.

[0079] Therefore, the relationship between the command rotation speed and the time required to reach the specified timing after the motor is started can be stored in the memory section of the control section 32, and that time can be used as a pre-set time for determining the specified timing.

[0080] In addition, since the specified timing is reached in a shorter time when the instructed number of rotations is high than when the instructed number of rotations is low, the time required to reach this specified timing may be set to a time corresponding to when the instructed number of rotations is low, and this set time may also be used when the instructed number of rotations is high.

[0081] That is, the predetermined timing may be the timing when a preset time has elapsed after the motor has started, at which point the control unit 32 transitions from the first control to the second control.

[0082] The time required to reach the specified timing does not need to be limited to being calculated as the time from when the motor is started, but may be calculated as the time required for the difference δ between the command rotation speed and the actual rotation speed of motor 1 to become small, starting from the point where section A switches to section B.

[0083] As another method, the predetermined timing may be determined by utilizing the fact that as the actual rotation speed of motor 1 approaches the commanded rotation speed in a steady state, the absolute deviation between the commanded rotation speed and the actual rotation speed of motor 1 in a steady state naturally becomes smaller.

[0084] In other words, the specified timing may be the timing when the absolute deviation between the commanded rotation speed and the actual rotation speed of the motor 1 in a steady state falls within a predetermined threshold, at which point the control unit 32 transitions from the first control to the second control. For example, if the predetermined threshold is set to a value of 5% (=instructed rotation speed x 0.05) or less of the steady-state indicated rotation speed of motor 1, the rotation speed of motor 1 will be sufficiently close to a stable state, and it is thought that there will be no subsequent drastic changes in the rotation speed.

[0085] Furthermore, as another method, as the actual rotation speed of motor 1 approaches the command rotation speed in a steady state, the rotation speed naturally approaches a constant value, which means that the angular acceleration approaches zero, and this fact can be used to determine the specified timing.

[0086] That is, the predetermined timing may be the timing when the absolute value of the angular acceleration falls within a predetermined threshold value, and the control unit 32 may transition from the first control to the second control. For example, if the predetermined threshold is set to a value that is 1.5 times or less the maximum change in angular velocity that occurs due to the variation in the actual rotation speed of motor 1 relative to the indicated rotation speed in a steady state, as measured when the motor is rotating stably, the rotation speed of motor 1 will have sufficiently approached a stable state, and it is thought that there will be no subsequent drastic changes in the rotation speed.

[0087] When the motor 1 is driven in a steady state, the command rotation speed may change in accordance with changes in the required amount of oil supply, etc. However, in such cases, the command rotation speed does not deviate so far from the actual rotation speed that a drastic change in rotation speed occurs, as occurs in the early stages of motor drive, so even the second control can adequately follow it.

[0088] As described above, during the initial stage of motor drive (sections A and B) when the rotation speed of motor 1 changes drastically after motor start-up, control unit 32 switches the current supply to U phase, V phase, and W phase using the first control at the initial stage of motor drive, which is performed at the first timing when the magnetic pole position of rotor R is detected. In other words, since the current supply is switched using control that is not predictive control, the current supply can be switched without being affected by changes in rotation speed.

[0089] Then, at a predetermined timing (the boundary point between section B and section C) when the difference δ between the commanded rotation speed and the actual rotation speed of motor 1 becomes small and the operation state approaches a steady state where no drastic changes in the rotation speed occur, the control unit 32 transitions from the first control to the second control, so that even if the control for switching the power supply is based on the second control, which is a predictive control, it can be executed without any problems.

[0090] (Second embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. The basic configuration is the same as that of the first embodiment, so a description of the similarities will be omitted and only the differences will be mainly described. FIG. 6 is a diagram for explaining the second control of the second embodiment according to the present invention, and in the second embodiment, a case where wide-angle energization is performed as the second control is shown.

[0091] Figure 6 corresponds to Figure 4, and the way to read the figure is the same as that explained in Figure 4, but differs from Figure 4 in that the control state of the second control switching element shown on the bottom corresponds to wide-angle energization. Specifically, the difference from the advance angle control explained in FIG. 4 is that the range in which each switching element is turned on is expanded to the retard angle side.

[0092] As in FIG. 4 , in FIG. 6 , the dotted arrows indicate how the switching elements are controlled for the U-phase upper stage element U-FET1. As can be seen from FIG. 6 , at an electrical angle of 0°, first the magnetic pole position of the rotor R is detected, and then, based on this first timing, control is performed to appropriately advance the phase of the timing for turning on the next U-phase upper stage element U-FET1 to the advance angle side.

[0093] On the other hand, in the case of advance angle control, the U-phase upper stage element U-FET1 is turned off at a position where the phase is appropriately advanced toward the advance angle side from the first timing when an electrical angle of 120° is detected, whereas in the case of wide-angle conduction shown in FIG. 6, the turning off is performed at a position where the phase is appropriately delayed toward the retard angle side from the first timing when an electrical angle of 120° is detected. In addition, by widening the range of electrical angles at which the motor is turned on in this way, it is possible to improve characteristics such as noise, vibration, and torque ripple.

[0094] However, even in this wide-angle energization, the first timing at which the magnetic pole position of the rotor R is detected and the second timing at which the appropriate switching of the switching elements is performed are predicted based on the rotation speed of the motor 1, which is the same.

[0095] Therefore, similar to the case of the advance angle control of the first embodiment, when the rotation speed changes drastically, there is the same problem that it is difficult to predict the second timing.

[0096] However, as explained above, in the early stages of motor operation when rapid changes in rotation speed occur, the control unit 32 switches the energization using the first control, which is less affected by changes in rotation speed, and then transitions from the first control to the second control (wide-angle energization) at a predetermined timing when the motor approaches a steady-state operating state where rapid changes in rotation speed do not occur, so wide-angle energization can be performed without any problems.

[0097] Although the present invention has been described above based on specific embodiments, the present invention is not limited to the above embodiments.

[0098] For example, from the description of the embodiments, it is clear that a control method for a motor in which drive control using maximum current control is performed when the motor is started, and then transitions to drive control during steady state operation is also disclosed, in which a first control is performed at the beginning of motor drive, in which current supply to the U phase, V phase, and W phase is switched at a first timing when the magnetic pole position of the rotor R is detected, and a second control during steady state operation in which the switching is performed at a second timing different from the first timing, and the transition from the first control to the second control is performed at a predetermined timing when the operating state during steady state operation is approached.

[0099] In this way, the content that can be understood from the embodiments, as well as modifications and improvements to the embodiments, are included in the technical scope of the invention, and this is clear to those skilled in the art from the description of the claims. [Explanation of symbols]

[0100] 1...motor, 2...pump, 3...control device, 31...drive circuit, 32...control section, A, B, C...section, CU...U-phase winding, CV...V-phase winding, CW...W-phase winding, DT...dead time, HU...U-phase hall sensor, HV...V-phase hall sensor, HW...W-phase hall sensor, R...rotor, U-FET1...U-phase upper element, U-FET2...U-phase lower element, V-FET1...V-phase upper element, V-FET2...V-phase lower element, W-FET1...W-phase upper element, W-FET2...W-phase lower element, δ...differential

Claims

1. A motor control device that performs drive control using maximum current control at the time of motor startup and then transitions to drive control during steady state operation, The control device a control unit that switches current application to the U phase, the V phase, and the W phase; The control unit a first control at an initial stage of motor drive in which the switching is performed at a first timing when the magnetic pole position of the rotor is detected; a second control during a steady state in which the switching is performed at a second timing different from the first timing; The control unit performs the transition from the first control to the second control at a predetermined timing when the operating state approaches the steady state.

2. The control device according to claim 1 , wherein the second control is advance angle control or wide-angle energization.

3. 3. The control device according to claim 2, wherein the predetermined timing is a timing when a preset time has elapsed after the motor has started.

4. 3. The control device according to claim 2, wherein the predetermined timing is a timing when an absolute deviation between an instructed rotation speed and an actual rotation speed of the motor in the steady state after the motor has started falls within a predetermined threshold value.

5. 3. The control device according to claim 2, wherein the predetermined timing is a timing at which an absolute value of angular acceleration falls within a predetermined threshold value after the motor starts.

6. 6. The control device according to claim 3, wherein the magnetic pole position is detected by output signals from a U-phase Hall sensor, a V-phase Hall sensor, and a W-phase Hall sensor provided in the motor.

7. 6. The control device according to claim 3, wherein the magnetic pole position is detected by an output signal of an absolute angle sensor provided in the motor.

8. A motor control method that performs drive control using maximum current control at motor start-up and then transitions to drive control during steady state operation, comprising: a first control at the beginning of motor drive, which switches energization of the U-phase, V-phase, and W-phase at a first timing when the magnetic pole position of the rotor is detected; a second control during a steady state in which the switching is performed at a second timing different from the first timing; A control method in which the transition from the first control to the second control is performed at a predetermined timing when the operating state approaches the steady state.

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