Sensorless control device, electric oil pump device, and sensorless control method

Abstract

A sensorless control device, an electric oil pump device, and a sensorless control method. The sensorless control device has: a motor drive circuit; a phase detection section that detects a signal based on a back electromotive force output phase of a motor; a storage section that stores a voltage control pattern and a speed control pattern; a voltage control section that outputs a control voltage based on the voltage control pattern; and a conduction control section that controls a drive voltage and a conduction switching speed based on the control voltage and the speed control pattern. When starting the motor, the voltage control section changes the control voltage over time based on the voltage control pattern, and the conduction control section performs a forced commutation control in which the drive voltage is changed over time in synchronization with the control voltage and the conduction switching speed is changed over time based on the speed control pattern. During the forced commutation control, a combination of the drive voltage and the conduction switching speed at any time always satisfies a first function having a negative slope with the drive voltage and the conduction switching speed as variables.

Description

Technical Field

[0001] This invention relates to a sensorless control device, an electric oil pump device, and a sensorless control method. Background Technology

[0002] Hybrid vehicles have a hydraulic supply system that provides hydraulic pressure to the transmission, consisting of a mechanical oil pump driven by the engine and an electric oil pump driven by a motor. In such hybrid vehicles, the motor is controlled when the engine stops and the mechanical oil pump is inoperable, thereby enabling the electric oil pump to provide the hydraulic pressure required by the transmission.

[0003] As a motor control method, sensorless control is a well-known approach: instead of using position sensors such as Hall effect sensors, it utilizes the motor's back electromotive force (EMF) to detect the motor's phase, and controls the motor's energization based on this phase detection result. In sensorless control, to detect the motor's phase, it is necessary to detect the point where the motor's neutral point voltage and back EMF intersect, i.e., the zero-crossing point. However, if the motor's speed is not above a specified speed, no back EMF sufficient for detecting the zero-crossing point is generated. Therefore, when starting a motor using sensorless control, the motor is typically energized according to a predetermined starting sequence before the motor's speed reaches the detectable zero-crossing point.

[0004] As an example of a starting sequence, a known starting sequence is as follows: After fixing the motor's phase to a specific phase by performing DC excitation for a predetermined time, forced commutation control is performed. In this forced commutation control, a constant drive voltage is applied to the energized phase while the energized phase is forcibly switched at a constant energization switching speed. When the motor speed reaches a detectable zero-crossing speed through this starting sequence, the forced commutation control ends, and then sensorless control of the motor is performed based on the phase detection result of the motor obtained from the zero-crossing detection.

[0005] Patent Document 1 describes a sensorless motor starting method. When the detection pattern of the zero-crossing point captured during forced commutation control matches a pre-stored rule-based change pattern, the method switches from forced commutation control to sensorless control. In this starting method, when the pattern switching timing during forced commutation control is shorter than a predetermined time, hysteresis angle control is performed to switch to sensorless control.

[0006] Patent Document 1: Japanese Patent Application Publication No. 2008-271727

[0007] However, for the motor to rotate properly, the drive voltage V applied to the motor needs to be controlled to an appropriate value corresponding to the rotational speed F, according to the FV characteristic which depends on the motor's specifications. Since the rotational speed F and the drive voltage V are proportional, the FV characteristic can be represented by a linear function with a positive slope. The more the combination of rotational speed F and drive voltage V deviates from the FV characteristic, the more unstable the motor's rotation becomes, and the more difficult it is to control the motor properly.

[0008] Furthermore, when a motor is connected to a load such as an oil pump, the energy required to rotate the motor increases. Therefore, the drive voltage required to rotate the motor connected to the load at the same speed as when it is unloaded increases. That is, even for the same motor, the motor's FV characteristics vary depending on the load size.

[0009] In the case of starting a motor via sensorless control as described above, although forced commutation control is performed according to a predetermined combination of drive voltage and energizing switching speed, the actual motor speed may not match the energizing switching speed, depending on the magnitude of the drive voltage and the load. Therefore, it is preferable to experimentally obtain the FV characteristics under various load conditions in advance, and when starting the motor via sensorless control, perform forced commutation control according to a combination of drive voltage and energizing switching speed with FV characteristics suitable for the actual load size. However, this method is difficult to implement in practice.

[0010] Therefore, a practical approach often employs the following method: While adjusting the drive voltage and switching speed based on the FV characteristics obtained under a specific load condition, forced commutation control is performed. This allows the combination of drive voltage and switching speed that enables the motor to rotate to a detectable zero-crossing speed to be determined experimentally beforehand. In this case, forced commutation control is performed during motor startup according to the drive voltage and switching speed combination determined by the above method. However, if the actual load conditions deviate significantly from the experimental load conditions, forced commutation control will be performed using a drive voltage and switching speed combination unsuitable for the actual load conditions. As a result, the motor may not be able to rotate to a detectable zero-crossing speed during startup, leading to motor startup failure. Summary of the Invention

[0011] In view of the above, one of the objects of the present invention is to provide a sensorless control device, an electric oil pump device, and a sensorless control method that can successfully start a motor regardless of the load size when starting the motor by sensorless control.

[0012] One aspect of the present invention provides a sensorless control device for controlling a motor without a position sensor. This sensorless control device includes: a motor drive circuit composed of multiple phase switching elements that provides power to each phase of the motor; and a phase detection unit that detects the phase of the motor based on the back electromotive force of the motor and outputs a phase detection signal representing the detection result of the phase. Furthermore, this sensorless control device includes a storage unit that stores a voltage control pattern and a speed control pattern. The voltage control pattern represents a control pattern for the drive voltage applied to the energized phase of the motor, and the speed control pattern represents a control pattern for the speed at which the energized phase is switched, i.e., the energization switching speed. Additionally, this sensorless control device includes a voltage control unit that outputs a control voltage based on a control command signal input from a higher-level control device, the phase detection signal, and the voltage control pattern. One aspect of the sensorless control device of the present invention further includes a power-on control unit that controls the switching element of the motor drive circuit according to the control voltage, the phase detection signal, and the speed control pattern, thereby controlling the drive voltage and the power-on switching speed. In one aspect of the sensorless control device of the present invention, when the motor is started, if the phase cannot be identified according to the phase detection signal, the voltage control unit changes the control voltage over time according to the voltage control pattern, and the power-on control unit controls the switching element according to the control voltage and the speed control pattern, thereby performing forced commutation control as follows: while changing the drive voltage over time synchronously with the control voltage, the power-on switching speed changes over time according to the speed control pattern. During the forced commutation control, the combination of the drive voltage and the power-on switching speed at any given time always satisfies a linear function with the drive voltage and the power-on switching speed as variables and having a negative slope.

[0013] An electric oil pump device according to one aspect of the present invention comprises: a motor having a shaft; a pump located on one axial side of the shaft and driven by the motor via the shaft to spray oil; and a sensorless control device of the above-described manner, which controls the motor without a position sensor.

[0014] One aspect of the present invention provides a sensorless control method for controlling a motor without a position sensor. When the motor is started, if the phase of the motor cannot be identified, forced commutation control is performed as follows: a drive voltage applied to the energized phase of the motor is varied over time according to a predetermined voltage control pattern, and an energization switching speed, which is the switching speed of the energized phase, is varied over time according to a predetermined speed control pattern. During the forced commutation control, the combination of the drive voltage and the energization switching speed at any given time always satisfies a linear function with a negative slope, using the drive voltage and the energization switching speed as variables.

[0015] According to the above-described manner of the present invention, a sensorless control device, an electric oil pump device, and a sensorless control method are provided that can successfully start a motor regardless of the load size when starting the motor by sensorless control. Attached Figure Description

[0016] Figure 1 This is a block diagram schematically showing an electric oil pump device having the sensorless control device of this embodiment.

[0017] Figure 2 This is a diagram illustrating an example of the power-on pattern and phase pattern used in the sensorless 120° power-on method of this embodiment.

[0018] Figure 3 This is a timing diagram illustrating the basic principle of the sensorless 120° power-on method of this embodiment.

[0019] Figure 4 This is a graph showing the relationship between the FV characteristics of the motor in this embodiment and the load.

[0020] Figure 5 This diagram illustrates an example of the voltage control pattern and speed control pattern stored in the storage unit in this embodiment.

[0021] Figure 6 This is a diagram showing other examples of voltage control patterns and speed control patterns stored in the storage unit in this embodiment.

[0022] Figure 7 This is a diagram showing other examples of voltage control patterns and speed control patterns stored in the storage unit in this embodiment.

[0023] Figure 8 This is a diagram showing other examples of voltage control patterns and speed control patterns stored in the storage unit in this embodiment.

[0024] Figure 9This is a timing diagram illustrating the operation of the sensorless control device of this embodiment.

[0025] Label Explanation

[0026] 10: Sensorless control device; 11: Motor drive circuit; 12: Phase detection unit; 12a: Zero-crossing detection circuit; 12b: Signal delay circuit; 13: Storage unit; 14: Voltage control unit; 15: Power-on control unit; 20: Motor; 30: Pump; 40: Electric oil pump; 100: Electric oil pump device; 200: Oil; 300: Vehicle battery; 400: Upper control device. Detailed Implementation

[0027] Hereinafter, the structure of one embodiment of the present invention will be described in detail with reference to the accompanying drawings.

[0028] Figure 1 This is a schematic circuit block diagram of an electric oil pump device 100 having the sensorless control device 10 of this embodiment. Figure 1 As shown, the electric oil pump unit 100 includes a sensorless control device 10 and an electric oil pump 40. The electric oil pump 40 includes a motor 20 and a pump 30. The electric oil pump unit 100 is, for example, a device for supplying oil to a transmission installed in a hybrid vehicle.

[0029] The sensorless control device 10 is a device that controls the motor 20 of the electric oil pump 40 without the presence of position sensors such as Hall sensors. That is, the sensorless control device 10 uses the back electromotive force of the motor 20 to detect the phase of the motor 20, and controls the energization of the motor 20 based on the detection result of this phase. The details of the vehicle control device 200 will be described later.

[0030] Motor 20 is, for example, an internal rotor type three-phase brushless DC motor, and is a sensorless motor without position sensors such as Hall sensors. Motor 20 has a shaft 21, U-phase terminal 22u, V-phase terminal 22v, W-phase terminal 22w, U-phase coil 23u, V-phase coil 23v, and W-phase coil 23w.

[0031] In addition, although Figure 1 The diagram is omitted, but motor 20 has a motor housing and a rotor and stator housed within the motor housing. The rotor is a rotating body supported by bearing components inside the motor housing. The stator is fixed inside the motor housing in a manner that surrounds the outer circumference of the rotor, generating the electromagnetic force required to rotate the rotor.

[0032] Shaft 21 is a shaft-like body coaxially connected to the rotor, extending radially inward along the rotor axis. The U-phase terminal 22u, V-phase terminal 22v, and W-phase terminal 22w are exposed metal terminals on the surface of the motor housing. These terminals are electrically connected to the motor drive circuit 11 of the sensorless control device 10, as detailed later. The U-phase coil 23u, V-phase coil 23v, and W-phase coil 23w are excitation coils located on the stator. The U-phase terminals 22u, V-phase terminals 22v, and W-phase terminals 22w are connected in a star configuration inside the motor 20.

[0033] The U-phase coil 23u is electrically connected between the U-phase terminal 22u and the neutral point N. The V-phase coil 23v is electrically connected between the V-phase terminal 22v and the neutral point N. The W-phase coil 23w is electrically connected between the W-phase terminal 22w and the neutral point N. By controlling the energizing states of the U-phase terminal 22u, V-phase terminal 22v, and W-phase terminal 22w by the sensorless control device 10, the electromagnetic force required to rotate the rotor is generated. As the rotor rotates, the shaft 21 also rotates synchronously with the rotor.

[0034] Pump 30 is located on one axial side of shaft 21 of motor 20. Pump 30 is driven by motor 20 via shaft 21 to spray oil 200. Pump 30 has an oil inlet 31 and an oil outlet 32. After oil 200 is drawn into the interior of pump 30 through oil inlet 31, it is sprayed out from oil outlet 32 ​​toward a transformer (not shown). Thus, pump 30 and motor 20 are adjacent and connected axially on shaft 21, thereby constituting electric oil pump 40.

[0035] The sensorless control device 10 includes a motor drive circuit 11, a phase detection unit 12, a storage unit 13, a voltage control unit 14, and a power-on control unit 15. The sensorless control device 10 is electrically connected to the motor 20, the vehicle battery 300, and the host control device 400. However, the vehicle battery 300 and the host control device 400 are not components of the sensorless control device 10 and the electric oil pump device 100.

[0036] The on-board battery 300 is one of several batteries used in hybrid vehicles, for example, to provide a 12V power supply voltage V to a 12V on-board system. M The upper-level control device 400, for example, is one of multiple ECUs (Electric Control Units) installed in a hybrid vehicle, which outputs a control command signal CS to the sensorless control device 10. The control command signal CS controls the electric oil pump device 100 to supply hydraulic pressure to the transformer.

[0037] The motor drive circuit 11, composed of multi-phase switching elements, is a circuit that supplies power to each phase of the motor 20. Specifically, the motor drive circuit 11 has a U-phase upper arm switch Q. UH V-phase upper arm switch Q VH W-phase upper arm switch Q WH U-phase lower side arm switch Q UL V-phase lower arm switch Q VL and the W-phase lower side arm switch Q WL In this embodiment, each arm switch is, for example, an N-channel MOS-FET.

[0038] U-phase upper arm switch Q UH The drain terminal, the upper arm switch of phase V, Q VH The drain terminal and the upper arm switch of phase W Q WH The drain terminals are electrically connected to the positive terminal of the vehicle battery 300. The U-phase lower arm switch Q... UL The source extreme element, V-phase lower side arm switch Q VL The source extreme element and the lower side arm switch Q of the W phase WL The source terminals are electrically connected to the negative terminals of the vehicle battery 300. Additionally, the negative terminals of the vehicle battery 300 are electrically connected to the vehicle's grounding terminal.

[0039] U-phase upper arm switch Q UH The source terminal is connected to the U-phase terminal 22u of motor 20 and the U-phase lower arm switch Q. UL The drain terminals are electrically connected respectively. The upper arm switch Q of phase V is connected. VH The source terminal is connected to the V-phase terminal 22V of motor 20 and the V-phase lower arm switch Q. VL The drain terminals are electrically connected respectively. The upper arm switch Q of phase W is connected. WH The source terminal and motor 20's W-phase terminal 22w and W-phase lower arm switch Q WL The drain terminals are electrically connected respectively.

[0040] U-phase upper arm switch Q UH The gate terminal, the upper arm switch Q of the V phase VH The gate terminal and the upper arm switch Q of phase W WH The gate terminals are electrically connected to the power-on control unit 15. Furthermore, the lower arm switch Q of phase U is... UL The gate terminal, the lower arm switch of the V phase Q VL The gate terminal and the lower arm switch Q of phase W WL The gate terminals are also electrically connected to the power-on control unit 15.

[0041] As described above, the motor drive circuit 11 is an inverter consisting of a three-phase full-bridge circuit with three upper arm switches and three lower arm switches. The motor drive circuit 11 configured in this way converts the DC power supplied by the vehicle battery 300 into three-phase power and outputs it to the motor 20 by controlling the switching of each arm switch through the power-on control unit 15.

[0042] In this embodiment, a sensorless 120° energization method is illustrated as the energization method for the motor 20. For ease of explanation, the basic principle of the sensorless 120° energization method will be explained below, followed by a description of the structure of the phase detection unit 12, the storage unit 13, the voltage control unit 14, and the energization control unit 15. Furthermore, the basic principle of the sensorless 120° energization method described below is merely an example, and the present invention is not limited thereto.

[0043] When using a sensorless 120° power-on method, according to Figure 2 The energized pattern shown controls the switching of each arm switch. For example... Figure 2 As shown, the energizing pattern for the 120° energizing method includes six energizing patterns: PA1, PA2, PA3, PA4, PA5, and PA6. In Figure 2 In the middle, from "Q" UH "to "Q WL In the column of “1” and “0”, “1” means that the corresponding arm switch is controlled to be on, and “0” means that the corresponding arm switch is controlled to be off.

[0044] exist Figure 3 In the diagram, the energizing period P1 from time t10 to time t11 represents the period during which the switching control of each arm switch is performed according to the energizing pattern PA1. During this energizing period P1, the upper arm switch Q of phase U... UH and W-phase lower side arm switch Q WL The circuit is on, and the other arm switches are off. During the energizing period P1, only the upper arm switch Q of phase U is active. UH The switch is controlled by a predetermined duty cycle. The duty cycle is controlled by the control voltage VC output from the voltage control unit 14 (described later). During the energizing period P1, the drive current flows from the U-phase terminal 22u to the W-phase terminal 22w in the U-phase coil 23u and the W-phase coil 23w. That is, the energized phases during the energizing period P1 are the U-phase and the W-phase.

[0045] exist Figure 3 In the diagram, the energizing period P2 from time t11 to time t12 represents the period during which the switching control of each arm switch is performed according to the energizing pattern PA2. During this energizing period P2, the upper arm switch Q of phase U... UH and V-phase lower side arm switch Q VLThe circuit is on, and the other arm switches are off. During the energizing period of P2, only the upper arm switch Q of phase U is off. UH It is controlled by a switch with a specified duty cycle. During the energizing period P2, the drive current flows from the U-phase terminal 22u to the V-phase terminal 22v in the U-phase coil 23u and the V-phase coil 23v. That is, the energized phases during the energizing period P2 are the U-phase and the V-phase.

[0046] exist Figure 3 In the diagram, the energizing period P3 from time t12 to time t13 represents the period during which the switching control of each arm switch is performed according to the energizing pattern PA3. During this energizing period P3, the upper arm switch Q of phase W... WH and V-phase lower side arm switch Q VL The circuit is on, and the remaining arm switches are off. During the energizing period P3, only the upper arm switch Q of phase W is active. WH It is controlled by a switch with a specified duty cycle. During the energizing period P3, the drive current flows from the W-phase terminal 22w to the V-phase terminal 22v in the W-phase coil 23w and the V-phase coil 23v. That is, the energized phases during the energizing period P3 are the W-phase and the V-phase.

[0047] exist Figure 3 In the diagram, the energizing period P4 from time t13 to time t14 represents the period during which the switching control of each arm switch is performed according to the energizing pattern PA4. During this energizing period P4, the upper arm switch Q of phase W... WH and U-phase lower side arm switch Q UL The circuit is on, and the remaining arm switches are off. This also applies to P4 during energization; only the upper arm switch Q of phase W is off. WH It is also controlled by a switch with a specified duty cycle. During the energizing period P4, the drive current flows from the W-phase terminal 22w to the U-phase terminal 22u in the W-phase coil 23w and the U-phase coil 23u. That is, the energized phases during the energizing period P4 are the W-phase and the U-phase.

[0048] exist Figure 3 In the diagram, the energizing period P5 from time t14 to time t15 represents the period during which the switching control of each arm switch is performed according to the energizing pattern PA5. During this energizing period P5, the upper arm switch Q of phase V... VH and U-phase lower side arm switch Q UL The circuit is on, and the remaining arm switches are off. During the energizing period P5, only the upper arm switch Q of phase V is on. VH It is controlled by a switch with a specified duty cycle. During the energizing period P5, the drive current flows from the V-phase terminal 22V to the U-phase terminal 22U in the V-phase coil 23V and the U-phase coil 23U. That is, the energized phases during the energizing period P5 are the V-phase and the U-phase.

[0049] exist Figure 3In the diagram, the energizing period P6 from time t15 to time t16 represents the period during which the switching control of each arm switch is performed according to the energizing pattern PA6. During this energizing period P6, the upper arm switch Q of phase V... VH and W-phase lower side arm switch Q WL The circuit is on, and the other arm switches are off. This also applies during the energizing period on P6; only the upper arm switch Q on phase V is off. VH It is controlled by a switch with a specified duty cycle. During the energizing period P6, the drive current flows from the V-phase terminal 22V to the W-phase terminal 22W in the V-phase coil 23V and the W-phase coil 23W. That is, the energized phases during the energizing period P6 are the V-phase and the W-phase.

[0050] By controlling the switching of each arm according to the above six energizing patterns, a rotating magnetic field is generated that causes the shaft 21 of motor 20 to rotate 360° in a certain direction. As a result, during the period from time t10 to time t16, the shaft 21 of motor 20 rotates 360° in a certain direction. In other words, during each period from energizing period P1 to energizing period P6, the shaft 21 of motor 20 rotates 60° in a certain direction.

[0051] The speed at which the energizing pattern switches, i.e., the speed at which the energizing phase switches, is called the energizing switching speed F. The unit of the energizing switching speed F is [Hz]. When the period for switching control according to an energizing pattern is set to P (seconds), the energizing switching speed Fs is expressed as [Fs = 1 / P]. The energizing switching speed F is sometimes also called the commutation frequency.

[0052] exist Figure 3 The waveforms of the voltages appearing at the U-phase terminal 22u, V-phase terminal 22v, and W-phase terminal 22w of the motor 20 are shown. Figure 3 In this context, "Vu" represents the U-phase terminal voltage appearing at the U-phase terminal 22u. "Vv" represents the V-phase terminal voltage appearing at the V-phase terminal 22v. "Vw" represents the W-phase terminal voltage appearing at the W-phase terminal 22w. Furthermore, the actual waveforms of the U-phase terminal voltage Vu, V-phase terminal voltage Vv, and W-phase terminal voltage Vw are waveforms with the same duty cycle as the switch, but... Figure 3 For simplicity, only the envelope of the voltage waveform is shown in the image.

[0053] The U-phase terminal voltage Vu is an effective voltage value determined by the switch duty cycle during energization periods P1 and P2, and a ground level value (0V) during energization periods P4 and P5. The V-phase terminal voltage Vv is an effective voltage value determined by the switch duty cycle during energization periods P5 and P6, and 0V during energization periods P2 and P3. The W-phase terminal voltage Vw is an effective voltage value determined by the switch duty cycle during energization periods P3 and P4, and 0V during energization periods P1 and P6. Thus, in the sensorless 120° energization mode, the phases for which the drive voltage required for the drive motor 20 is applied switch every 120°.

[0054] During the energizing period P3, although no drive current flows in the U-phase coil 23u, the energy stored in the U-phase coil 23u will be transmitted through the lower arm switch Q of the U-phase. UL The body diode causes a freewheeling current to flow in the U-phase coil 23u for a certain period of time. As a result, a ringing phenomenon occurs where the U-phase terminal voltage Vu is 0V for only a certain period of time from the beginning of period P3. Afterward, the U-phase terminal voltage Vu is consistent with the back electromotive force generated in the U-phase coil 23u. During the energizing period P3, at the middle of the energizing period P3, that is, when the motor 20 has rotated 30° from the beginning of the energizing period P3, the back electromotive force flows from the high-voltage side to the low-voltage side and interacts with the voltage of the neutral point N, that is, the neutral point voltage Vu. N Crossover.

[0055] Similarly, during the energizing period P6, although no drive current flows in the U-phase coil 23u, the energy stored in the U-phase coil 23u will flow through the upper arm switch Q of the U-phase. UH The body diode causes a freewheeling current to flow in the U-phase coil 23u for a certain period of time. As a result, the U-phase terminal voltage Vu becomes the power supply voltage V for only a certain period of time from the beginning of the energization period P6. M The ringing phenomenon occurs. Afterwards, the U-phase terminal voltage Vu coincides with the back electromotive force generated in the U-phase coil 23u. During the energizing period P6, at the midpoint of energizing period P6, i.e., when the motor 20 has rotated 30° from the beginning of energizing period P6, the back electromotive force flows from the low-voltage side towards the high-voltage side and coincides with the neutral point voltage Vu. N Crossover.

[0056] As described above, during the 360° rotation of motor 20, back electromotive force is exposed at the U-phase terminal 22u only during the energizing periods P3 and P6. Based on the same principle, during the 360° rotation of motor 20, back electromotive force is exposed at the V-phase terminal 22v only during the energizing periods P1 and P4, and back electromotive force is exposed at the W-phase terminal 22w only during the energizing periods P2 and P5. In the sensorless 120° energizing mode, the neutral point voltage V needs to be detected to detect the phase of motor 20. NThe point where the electromotive force intersects with the back electromotive force is the zero point.

[0057] exist Figure 3 In this context, "Zu" refers to the back electromotive force exposed at the U-phase terminal 22u, which becomes the neutral point voltage V. N The following condition occurs when the back electromotive force exposed to the U-phase terminal 22u becomes lower than the neutral point voltage V. N The high timing becomes the high-level U-phase zero-crossing detection signal. "Zv" is the neutral point voltage V when the back electromotive force exposed to the 22V V-phase terminal becomes the neutral point voltage. N The following conditions are met when the back electromotive force exposed to the 22V phase V terminal becomes lower than the neutral point voltage V. N The high timing becomes the high-level V-phase zero-crossing detection signal. "Zw" is the neutral point voltage V when the back electromotive force exposed to the W-phase terminal 22w becomes the neutral point voltage. N The following condition occurs when the back electromotive force exposed to the W-phase terminal 22W becomes lower than the neutral point voltage V. N The high timing becomes the high-level W-phase zero-crossing detection signal.

[0058] Alternatively, by simply inputting, for example, the U-phase terminal voltage Vu and the neutral point voltage V to the comparator... N Unable to obtain Figure 3 The U-phase zero-crossing detection signal Zu is shown. In practice, the comparator's output voltage undergoes prescribed waveform processing, thereby generating a voltage V that only crosses the neutral point. N The zero-crossing detection signal Zu for the U phase is generated when the zero-crossing point intersects with the back electromotive force. The zero-crossing detection signals Zv for the V phase and Zw for the W phase are generated using the same method.

[0059] exist Figure 3 In this context, "Hu" is the U-phase phase detection signal with a 30° phase delay relative to the U-phase zero-crossing detection signal Zu. "Hv" is the V-phase phase detection signal with a 30° phase delay relative to the V-phase zero-crossing detection signal Zv. "Hw" is the W-phase phase detection signal with a 30° phase delay relative to the W-phase zero-crossing detection signal Zw.

[0060] Furthermore, the motor 20 rotates 60° during the time interval between two adjacent zero-crossing points on the time axis. Therefore, by measuring the time interval between two adjacent zero-crossing points on the time axis and delaying the U-phase zero-crossing detection signal Zu by half the measurement time, a U-phase phase detection signal Hu with a phase delay of 30° relative to the U-phase zero-crossing detection signal Zu can be generated. The V-phase phase detection signal Hv and the W-phase phase detection signal Hw are generated in the same way.

[0061] like Figure 3As shown, the voltage levels of the U-phase phase detection signal Hu, the V-phase phase detection signal Hv, and the W-phase phase detection signal Hw vary regularly depending on six energizing patterns. Hereinafter, the patterns by which the voltage levels of the U-phase phase detection signal Hu, the V-phase phase detection signal Hv, and the W-phase phase detection signal Hw vary depending on the energizing patterns are referred to as phase patterns. Figure 2 As shown, the phase pattern of the sensorless 120° energization mode includes six phase patterns: PB1, PB2, PB3, PB4, PB5, and PB6. In Figure 2 In the middle, in "H" U "H" V "and "H W In the column of “1” and “0”, “1” means that the corresponding phase detection signal is high level and “0” means that the corresponding phase detection signal is low level.

[0062] In the sensorless 120° power-on mode, the phase pattern is identified based on three phase detection signals Hu, Hv, and Hw for each power-on period. The power-on pattern to be used in the next power-on period is determined based on the identification result of the phase pattern. Furthermore, when the phase pattern changes, the power-on pattern is switched to the next power-on pattern.

[0063] like Figure 3 As shown, for example, during the energizing period P1, the phase pattern of energizing period P1 is identified as phase pattern PB1 based on the phase detection signals Hu, Hv, and Hw. Since the phase pattern of energizing period P1 is phase pattern PB1, the energizing pattern PA2 is determined as the energizing pattern to be used in the next energizing period P2. Then, at the moment when the phase pattern PB1 changes, that is, at the moment when a falling edge is generated in the V-phase phase detection signal Hv, the energizing pattern is switched from energizing pattern PA1 to energizing pattern PA2.

[0064] In the sensorless 120° energization mode, the phase pattern recognition, energization pattern determination, and energization pattern switching are performed synchronously with the phase detection signals Hu, Hv, and Hw generated using the back electromotive force generated in the motor 20. This allows for energization control of the motor 20 without using position sensors such as Hall sensors. Hereinafter, the case of energizing the motor 20 synchronously with the phase detection signals Hu, Hv, and Hw generated using the back electromotive force generated in the motor 20 will be referred to as "sensorless synchronous control."

[0065] The above describes the basic principle of the sensorless 120° energization method. In this method, to generate phase detection signals Hu, Hv, and Hw, it is necessary to detect the neutral point voltage V of the motor 20. NThe point where the back electromotive force intersects with the zero-crossing point is the zero-crossing point. However, if the speed of motor 20 is not above the specified speed, a detectable zero-crossing back electromotive force will not be generated. Therefore, when starting motor 20 using a sensorless 120° energization method, the phase pattern cannot be identified based on the phase detection signals Hu, Hv, and Hw before the speed of motor 20 reaches the speed required to generate a detectable zero-crossing back electromotive force; that is, the phase of motor 20 cannot be identified, thus sensorless synchronous control is impossible. Therefore, when starting motor 20 using a sensorless 120° energization method, the energization control of motor 20 must be performed according to a predetermined starting sequence before the speed of motor 20 reaches the speed required to generate a detectable zero-crossing back electromotive force.

[0066] As an example of a starting sequence, the following starting sequence is known: after fixing the motor phase to a specific phase by performing DC excitation for a specified time, forced commutation control is performed to forcibly switch the energized phase while applying a constant drive voltage to the energized phase and at a constant energization switching speed.

[0067] like Figure 4 As shown, in order for motor 20 to rotate properly, the drive voltage V applied to motor 20 needs to be controlled to an appropriate value corresponding to the rotational speed F, based on the FV characteristic which depends on the specifications of motor 20. Since the rotational speed F and the drive voltage V are proportional, the FV characteristic can be represented by a linear function with a positive slope. The more the combination of rotational speed F and drive voltage V deviates from the FV characteristic, the more unstable the rotation of motor 20 becomes, and the more difficult it is to control motor 20 properly.

[0068] Furthermore, when motor 20 is connected to a load such as pump 30, the energy required to rotate motor 20 increases, thus increasing the drive voltage required to rotate motor 20 at the same speed as under no-load conditions. In other words, the FV characteristic of motor 20 varies depending on the load size. Figure 4 In the equation, LF0, a linear function with a positive slope, represents the FV characteristic of load T0. Figure 4 In the equation, a linear function LF1 with a positive slope represents the FV characteristic of a load T1 smaller than the load T0. Figure 4 In the equation, LF4, a linear function with a positive slope, represents the FV characteristic of a load T4 that is larger than the load T0. For example... Figure 4 As shown, the slope of the linear function representing the FV characteristic is constant regardless of the load, but the intercept of the linear function representing the FV characteristic varies depending on the load. That is, the smaller the load, the larger the intercept of the linear function representing the FV characteristic, and the larger the load, the smaller the intercept of the linear function representing the FV characteristic.

[0069] In the case of starting motor 20 via forced commutation control as described above, forced commutation control is performed according to a predetermined combination of drive voltage and energizing switching speed. However, the actual rotational speed of motor 20 may not be consistent with the energizing switching speed, depending on the magnitude of the drive voltage and the load. Therefore, as... Figure 4 As shown, preferably, the FV characteristics under various load conditions are obtained in advance through experiments. When the motor 20 is started by sensorless control, forced commutation control is performed according to the combination of drive voltage and energizing switching speed that conform to the FV characteristics corresponding to the actual load size. However, it is difficult to implement this method in reality.

[0070] Therefore, a practical approach often employs the following method: forced commutation control is performed while adjusting the drive voltage and switching speed based on the FV characteristics obtained under a specific load condition. This allows the combination of drive voltage and switching speed that enables the motor to rotate to a detectable zero-crossing speed to be determined experimentally beforehand. In this case, forced commutation control is performed according to the drive voltage and switching speed combination determined by the above method when starting the motor. However, if the actual load conditions deviate significantly from the experimental load conditions, forced commutation control will be performed using a drive voltage and switching speed combination unsuitable for the actual load conditions. As a result, the motor may fail to rotate to a detectable zero-crossing speed when starting, leading to motor start-up failure.

[0071] For example, in Figure 4 In this context, it is assumed that the drive voltage V0 and the switching speed F0 used in forced commutation control are determined based on the FV characteristics of the load T0. When a load T4, which is larger than the load T0, is connected to the motor 20, the drive voltage V0 determined by the FV characteristics of the load T0 deviates significantly from the FV characteristics of the load T4 towards the low-voltage side, and the switching speed F0 determined by the FV characteristics of the load T0 deviates significantly from the FV characteristics of the load T4 towards the high-speed side. As a result, a drive voltage V0 that is much lower than the drive voltage V4 suitable for the FV characteristics of the load T4 is applied to the motor 20, and the switching speed F0 that is much higher than the switching speed F4 suitable for the FV characteristics of the load T4 is used to switch the energized phase (energizing pattern), thereby limiting the motor 20 to not rotate due to the load.

[0072] On the other hand, when a load T1 smaller than the load T0 is connected to the motor 20, the drive voltage V0, determined by the FV characteristic of the load T0, deviates significantly from the FV characteristic of the load T1 towards the high-voltage side, and the energizing switching speed F0, determined by the FV characteristic of the load T0, deviates significantly from the FV characteristic of the load T1 towards the low-speed side. As a result, a drive voltage V0 much higher than the drive voltage V1 suitable for the FV characteristic of the load T1 is applied to the motor 20, and the energizing phase is switched at an energizing switching speed F0 much lower than the energizing switching speed F1 suitable for the FV characteristic of the load T1. Consequently, the motor 20 may experience significant vibration and become uncontrollable.

[0073] To address this problem, in this embodiment, when starting the motor 20, if the phase of the motor 20 cannot be identified, forced commutation control is performed as follows: The drive voltage applied to the energized phase of the motor 20 is varied over time according to a predetermined voltage control pattern, and the energization switching speed is varied over time according to a predetermined speed control pattern. However, the drive voltage and energization switching speed are not varied indefinitely during forced commutation control. Instead, the drive voltage and energization switching speed are varied while satisfying the condition that "during forced commutation control, the combination of drive voltage and energization switching speed at any given time always satisfies a linear function with a negative slope, using drive voltage and energization switching speed as variables."

[0074] Specifically, in the forced commutation control of this embodiment, for example, as Figure 4 As shown, the drive voltage V varies with time from a drive voltage V1 with FV characteristics suitable for load T1 to a drive voltage V4 with FV characteristics suitable for load T4, while the switching speed F varies from a switching speed F1 with FV characteristics suitable for load T1 to a switching speed F4 with FV characteristics suitable for load T4. During forced commutation control, the combination of drive voltage V and switching speed F at any given time always satisfies a linear function LF with drive voltage V and switching speed F as variables and a negative slope. In other words, during forced commutation control, in a two-axis coordinate plane with drive voltage V as the horizontal axis and switching speed F as the vertical axis, the intersection of drive voltage V and switching speed F at any given time always lies on the straight line represented by the linear function LF.

[0075] By performing the forced commutation control described above when starting the motor 20, the FV characteristic suitable for the combination of drive voltage V and energizing switching speed F varies with time within the range from the FV characteristic of load T1 to the FV characteristic of load T4. That is, the range of the FV characteristic that can be stably controlled by the motor 20 can be expanded, resulting in the motor 20 being able to stably rotate to a speed that generates a detectable back electromotive force regardless of the load size when starting the motor 20, thus enabling successful starting of the motor 20.

[0076] Furthermore, in a two-axis coordinate plane with the driving voltage V as the horizontal axis and the energizing switching speed F as the vertical axis, a linear function LF with a negative slope preferably intersects at a right angle with, for example, a linear function LF0 with a positive slope representing the FV characteristic of the load T0.

[0077] Hereinafter, based on the explanation of the basic principle of the sensorless 120° power-on method described above and the explanation of the forced commutation control implemented when starting the motor 20 in this embodiment, the phase detection unit 12, storage unit 13, voltage control unit 14 and power-on control unit 15 provided by the sensorless control device 10 of this embodiment will be explained.

[0078] The phase detection unit 12 detects the phase of the motor 20 based on the back electromotive force of the motor 20, and outputs phase detection signals Hu, Hv, and Hw, representing the phase detection results, to the voltage control unit 14 and the power-on control unit 15. The phase detection unit 12 is electrically connected to the U-phase terminal 22u, V-phase terminal 22v, and W-phase terminal 22w of the motor 20, respectively. Additionally, the phase detection unit 12 is connected to the upper arm switch Q of the W-phase. WH The drain terminal is electrically connected. The phase detection unit 12 is input with the U-phase terminal voltage Vu, V-phase terminal voltage Vv, W-phase terminal voltage Vw, and power supply voltage V. M .

[0079] The phase detection unit 12 includes a zero-crossing detection circuit 12a and a signal delay circuit 12b. The zero-crossing detection circuit 12a determines the signal based on the power supply voltage V. M Generating neutral point voltage V N (=V M / 2). Furthermore, the zero-crossing detection circuit 12a detects the U-phase terminal voltage Vu and the neutral point voltage V based on... N The U-phase zero-crossing detection signal Zu is generated and output to the signal delay circuit 12b. The back electromotive force of the U-phase zero-crossing detection signal Zu exposed at the U-phase terminal 22u becomes the neutral point voltage V. N The following condition occurs when the back electromotive force exposed to the U-phase terminal 22u becomes lower than the neutral point voltage V. N The high-level signal is triggered when the signal is high.

[0080] As described above, this is achieved solely by, for example, inputting the U-phase terminal voltage Vu and the neutral point voltage V to the comparator. N Unable to obtain Figure 3 The zero-crossing detection signal Zu for phase U is shown. Therefore, the zero-crossing detection circuit 12a detects the input phase U terminal voltage Vu and neutral point voltage V. N The comparator's output voltage undergoes specified waveform processing, thereby generating a voltage V that is only available at the neutral point. N The zero-crossing detection signal Zu of the U-phase is the edge of the zero-crossing point that intersects with the back electromotive force exposed at the U-phase terminal 22u.

[0081] In addition, the zero-crossing detection circuit 12a detects the voltage Vv at the V-phase terminal and the neutral point voltage V based on the voltage V at the neutral point. N The zero-crossing detection signal Zv of phase V is generated and output to the signal delay circuit 12b. The back electromotive force of the zero-crossing detection signal Zv exposed to the phase V terminal 22V becomes the neutral point voltage V. N The following conditions are met when the back electromotive force exposed to the 22V phase V terminal becomes lower than the neutral point voltage V. N The high-level signal is triggered when the voltage reaches a high level. The zero-crossing detection circuit 12a detects the input V-phase terminal voltage Vv and the neutral point voltage V. N The comparator's output voltage undergoes specified waveform processing, thereby generating a voltage V that is only available at the neutral point. N The zero-crossing detection signal Zv of the V-phase is the edge of the zero-crossing point that intersects with the back electromotive force exposed at the V-phase terminal 22V.

[0082] Furthermore, the zero-crossing detection circuit 12a detects the W-phase terminal voltage Vw and the neutral point voltage V based on the zero-crossing detection circuit 12a. N The zero-crossing detection signal Zw for phase W is generated and output to the signal delay circuit 12b. The back electromotive force of the zero-crossing detection signal Zw exposed at the phase W terminal 22w becomes the neutral point voltage V. N The following condition occurs when the back electromotive force exposed to the W-phase terminal 22W becomes lower than the neutral point voltage V. N The high-level signal is triggered when the signal is high. The zero-crossing detection circuit 12a detects the input W-phase terminal voltage Vw and the neutral point voltage V. N The comparator's output voltage undergoes specified waveform processing, thereby generating a voltage V that is only available at the neutral point. N The zero-crossing detection signal Zw of phase W, which intersects with the back electromotive force exposed at phase W terminal 22w, is the zero-crossing detection signal of phase W.

[0083] Signal delay circuit 12b generates a U-phase phase detection signal Hu with a 30° phase delay relative to the U-phase zero-crossing detection signal Zu, and outputs it to voltage control unit 14 and power-on control unit 15. Additionally, signal delay circuit 12b generates a V-phase phase detection signal Hv with a 30° phase delay relative to the V-phase zero-crossing detection signal Zv, and outputs it to voltage control unit 14 and power-on control unit 15. Furthermore, signal delay circuit 12b generates a W-phase phase detection signal Hw with a 30° phase delay relative to the W-phase zero-crossing detection signal Zw, and outputs it to voltage control unit 14 and power-on control unit 15. Thus, signal delay circuit 12b outputs three phase detection signals Hu, Hv, and Hw to voltage control unit 14 and power-on control unit 15.

[0084] As described above, the motor 20 rotates 60° within the time interval between two adjacent zero-crossing points on the time axis. The signal delay circuit 12b measures the time interval between two adjacent zero-crossing points on the time axis and delays the U-phase zero-crossing detection signal Zu by half the measurement time, thereby generating a U-phase phase detection signal Hu with a phase delay of 30° relative to the U-phase zero-crossing detection signal Zu. The signal delay circuit 12b generates the V-phase phase detection signal Hv and the W-phase phase detection signal Hw in the same way.

[0085] The storage unit 13 stores various data required for controlling the motor 20 via sensorless 120° energization. The storage unit 13 includes non-volatile memory such as EEPROM and volatile memory such as RAM. The storage unit 13 pre-stores... Figure 2 The energizing pattern and phase pattern are shown. Additionally, the storage unit 13 pre-stores DC excitation conditions in which the phase of the motor 20 is fixed at a specific phase. Furthermore, the storage unit 13 pre-stores a voltage control pattern representing the control pattern of the drive voltage V and a speed control pattern representing the control pattern of the energizing switching speed F.

[0086] For example, such as Figure 5 As shown, the voltage control pattern is a pattern in which the driving voltage V increases from driving voltage V1 to driving voltage V4 with a constant slope over time t. Driving voltage V1 is the value of driving voltage V suitable for the FV characteristics of load T1, and driving voltage V4 is the value of driving voltage V suitable for the FV characteristics of load T4. Driving voltage V1 is lower than driving voltage V4. Furthermore, as... Figure 5 As shown, the speed control pattern is a pattern in which the switching speed F decreases at a constant slope from switching speed F1 to switching speed F4 over time t. Switching speed F1 is the value of switching speed F suitable for the FV characteristics of load T1, and switching speed F4 is the value of switching speed F suitable for the FV characteristics of load T4. Switching speed F1 is higher than switching speed F4.

[0087] exist Figure 5 For example, the combination "V1, F1" of the driving voltage V and the switching speed F at time t0 satisfies a linear function LF. Furthermore, the combination "V0, F0" of the driving voltage V and the switching speed F at time t100 also satisfies a linear function LF. Moreover, the combination "V4, F4" of the driving voltage V and the switching speed F at time t200 also satisfies a linear function LF. Thus, in this embodiment, the voltage control pattern and the speed control pattern satisfy the condition that "the combination of the driving voltage V and the switching speed F at any given time always satisfies a linear function LF with the driving voltage V and the switching speed F as variables and having a negative slope."

[0088] In addition, such as Figure 6 As shown, as another example of a voltage control pattern, the storage unit 13 can also store a voltage control pattern in which the driving voltage V decreases from the driving voltage V4 to the driving voltage V1 with a constant slope over time t. Furthermore, as... Figure 6 As shown, as another example of a speed control pattern, the storage unit 13 may also store a speed control pattern in which the power-on switching speed F increases from the power-on switching speed F4 to the power-on switching speed F1 with a constant slope over time t. Figure 6 The voltage control pattern and speed control pattern shown also satisfy the condition that "the combination of the driving voltage V and the energizing switching speed F at any time always satisfies the condition that the driving voltage V and the energizing switching speed F are a linear function LF with a negative slope".

[0089] In addition, such as Figure 7 As shown, as another example of a voltage control pattern, the storage unit 13 can also store a voltage control pattern in which the driving voltage V increases in stages from the driving voltage V1 to the driving voltage V4 over time t. Furthermore, as... Figure 7 As shown, as another example of a speed control pattern, the storage unit 13 may also store a speed control pattern in which the power-on switching speed F decreases in stages from the power-on switching speed F1 to the power-on switching speed F4 over time t. Figure 7 The voltage control pattern and speed control pattern shown also satisfy the condition that "the combination of the driving voltage V and the energizing switching speed F at any time always satisfies the condition that the driving voltage V and the energizing switching speed F are a linear function LF with a negative slope".

[0090] Moreover, such as Figure 8 As shown, as another example of a voltage control pattern, the storage unit 13 can also store a voltage control pattern in which the driving voltage V decreases in stages from the driving voltage V4 to the driving voltage V1 over time t. Furthermore, as... Figure 8As shown, as another example of a speed control pattern, the storage unit 13 may also store a speed control pattern in which the power-on switching speed F increases in stages from the power-on switching speed F4 to the power-on switching speed F1 over time t. Figure 8 The voltage control pattern and speed control pattern shown also satisfy the condition that "the combination of the driving voltage V and the energizing switching speed F at any time always satisfies the condition that the driving voltage V and the energizing switching speed F are a linear function LF with a negative slope".

[0091] The voltage control unit 14 outputs a control voltage VC to the power-on control unit 15 based on various data, including the control command signal CS input from the upper control device 400, the phase detection signals Hu, Hv, and Hw input from the phase detection unit 12, and the voltage control pattern stored in the storage unit 13. The control voltage VC determines the switching duty cycle, and the switching duty cycle determines the value of the driving voltage V applied to the energized phase, i.e., the effective voltage value.

[0092] The power-on control unit 15 controls the switching of each arm of the motor drive circuit 11 based on various data including the control voltage VC input from the voltage control unit 14, the phase detection signals Hu, Hv, and Hw input from the phase detection unit 12, and the speed control pattern stored in the storage unit 13, thereby controlling the drive voltage V and the power-on switching speed F.

[0093] When starting motor 20, if the phase of motor 20, i.e., the phase pattern, cannot be identified based on the phase detection signals Hu, Hv, and Hw, the voltage control unit 14 and the power-on control unit 15 enter a forced commutation control mode. In forced commutation mode, the voltage control unit 14 changes the control voltage VC over time according to the voltage control pattern stored in the storage unit 13, and the power-on control unit 15 controls each arm switch based on the control voltage VC input from the voltage control unit 14 and the speed control pattern stored in the storage unit 13. This performs forced commutation control by simultaneously changing the drive voltage V over time in sync with the control voltage VC, and changing the power-on switching speed F over time according to the speed control pattern. During forced commutation control, the combination of the drive voltage V and the power-on switching speed F at any given time always satisfies a linear function LF with a negative slope, where the drive voltage V and the power-on switching speed F are variables. When starting the motor 20, if the phase pattern cannot be identified based on the phase detection signals Hu, Hv, and Hw, the voltage control unit 14 and the energizing control unit 15 enter a DC excitation mode for DC excitation control before entering the forced commutation mode. In the DC excitation mode, before outputting the control voltage VC according to the voltage control pattern, the voltage control unit 14 outputs the control voltage VC according to the DC excitation conditions stored in the storage unit 13. The energizing control unit 15 controls the switches of each arm according to the control voltage VC input from the voltage control unit 14 and the DC excitation conditions, thereby applying a DC drive voltage for a certain period of time to a specific energized phase.

[0094] In forced commutation mode, when the phase pattern is successfully identified based on the phase detection signals Hu, Hv, and Hw, the voltage control unit 14 and the power-on control unit 15 enter a sensorless synchronization control mode for sensorless synchronization control. In the sensorless synchronization control mode, the voltage control unit 14 outputs a control voltage VC based on the control command signal CS input from the upper control device 400 and the phase detection signals Hu, Hv, and Hw. The power-on control unit 15 controls the switches of each arm based on the control voltage VC input from the voltage control unit 14 and the phase detection signals Hu, Hv, and Hw. Thus, while applying a drive voltage V corresponding to the control command signal CS to the energized phase, the energized phase is switched at an energization switching speed F determined by the phase detection signals Hu, Hv, and Hw.

[0095] The following is for reference Figure 9 The timing diagram shown illustrates the operation of the sensorless control device 10 configured as described above.

[0096] exist Figure 9At time t1, a control command signal CS is input to the voltage control unit 14 from the host control device 400. For example, the control command signal CS is an analog voltage signal with a voltage value representing the target rotational speed. When the control command signal CS is input at time t1, the voltage control unit 14 determines whether there is a phase pattern in the six phase patterns stored in the storage unit 13 that matches the state of the phase detection signals Hu, Hv, and Hw.

[0097] At time t1, motor 20 is stopped, therefore no back electromotive force is generated. In this case, the zero-crossing detection circuit 12a cannot detect the zero-crossing point, therefore... Figure 9 As shown, the zero-crossing detection signals Zu, Zv, and Zw output from the zero-crossing detection circuit 12a are all at low levels. Consequently, the phase detection signals Hu, Hv, and Hw output from the signal delay circuit 12b are also all at low levels. In this case, the phase pattern of the motor 20 cannot be identified based on the phase detection signals Hu, Hv, and Hw. Therefore, at time t1, the voltage control unit 14 determines that there is no phase pattern consistent with the state of the phase detection signals Hu, Hv, and Hw and switches to DC excitation mode.

[0098] When the system transitions to DC excitation mode at time t1, the voltage control unit 14 outputs a control voltage VC to the power-on control unit 15, which has a voltage value representing, for example, a switching duty cycle of 15% to 25%, based on the DC excitation conditions stored in the storage unit 13. Furthermore, the voltage control unit 14 begins timing operation from the time t1 when the system transitions to DC excitation mode.

[0099] When the power-on control unit 15 is input with a control voltage VC having a voltage value representing, for example, a switching duty cycle of 15% to 25%, at time t1, it determines whether there is a phase pattern among the six phase patterns stored in the storage unit 13 that matches the state of the phase detection signals Hu, Hv, and Hw. As described above, at time t1, the phase detection signals Hu, Hv, and Hw are all at a low level. Therefore, at time t1, the power-on control unit 15 determines that there is no phase pattern that matches the state of the phase detection signals Hu, Hv, and Hw. When the power-on control unit 15 is input with a control voltage VC having a voltage value representing, for example, a switching duty cycle of 15% to 25%, and there is no phase pattern that matches the state of the phase detection signals Hu, Hv, and Hw, it switches to DC excitation mode.

[0100] After switching to DC excitation mode at time t1, the power-on control unit 15 starts switching control of each arm switch based on the control voltage VC input from the voltage control unit 14 and the DC excitation conditions stored in the storage unit 13. Specifically, for example, as Figure 9 As shown, the power-on control unit 15 switches the upper arm switch Q of phase U. UHW-phase upper arm switch Q WH and the V-phase lower arm switch Q VL When the circuit is turned on, the remaining arm switches are turned off. At this time, the energizing control unit 15 controls the upper arm switch Q of phase U with a switching duty cycle determined by the control voltage VC, for example, a switching duty cycle of 15% to 25%. UH and W phase upper arm switch Q WH .

[0101] Through the operation of the voltage control unit 14 and the power-on control unit 15 in the DC excitation mode described above, such as Figure 9 As shown, after time t1, the U-phase terminal voltage Vu and the W-phase terminal voltage Vw become voltage values ​​corresponding to, for example, a switching duty cycle of 15% to 25%, and the V-phase terminal voltage Vv becomes 0V. As a result, in DC excitation mode, a DC drive voltage is applied to a specific energized phase. Through such DC excitation control, the shaft 21 of the motor 20 rotates to a specific phase and stops. That is, through DC excitation control, the phase of the motor 20 is fixed at a specific phase. The voltage control unit 14, upon detecting, for example, at time t2, that the time required to fix the shaft 21 of the motor 20 at the specific phase has elapsed through a timing operation starting from time t1, switches to forced commutation mode.

[0102] Furthermore, the actual waveforms of the U-phase terminal voltage Vu, V-phase terminal voltage Vv, and W-phase terminal voltage Vw are waveforms with the same duty cycle as the switch, but... Figure 9 For simplicity, only the envelope of the voltage waveform is shown in the figure.

[0103] When the system transitions to forced commutation mode at time t2, the voltage control unit 14 outputs a control voltage VC to the power-on control unit 15 according to the voltage control pattern stored in the storage unit 13. For example, as... Figure 5 As shown, when a voltage control pattern in which the driving voltage V increases with time t at a constant slope is stored in the storage unit 13, the voltage control unit 14 outputs a control voltage VC that increases with time t at a constant slope starting from time t2.

[0104] As other examples, such as Figure 6 As shown, when a voltage control pattern in which the driving voltage V decreases with time t at a constant slope is stored in the storage unit 13, the voltage control unit 14 outputs a control voltage VC that decreases with time t at a constant slope starting from time t2. Other examples include... Figure 7 As shown, when a voltage control pattern in which the driving voltage V increases in stages with time t is stored in the storage unit 13, the voltage control unit 14 outputs a control voltage VC that increases in stages with time t starting from time t2. Other examples include... Figure 8As shown, when a voltage control pattern in which the driving voltage V decreases in stages with time t is stored in the storage unit 13, the voltage control unit 14 outputs a control voltage VC that decreases in stages with time t starting from time t2.

[0105] When the power-on control unit 15 receives a control voltage VC according to the voltage control pattern at time t2, it switches to forced commutation mode if there is no phase pattern consistent with the states of the phase detection signals Hu, Hv, and Hw. After switching to forced commutation mode at time t2, the power-on control unit 15 starts switching control of each arm switch according to the control voltage VC input from the voltage control unit 14 and the speed control pattern and power-on pattern stored in the storage unit 13.

[0106] Specifically, such as Figure 9 As shown, after time t2, the power-on control unit 15 generates a pulse signal, namely the power-on switching timing signal ST, having the same frequency as the power-on switching speed F determined according to the speed control pattern. The speed control pattern stored in the storage unit 13 is, for example... Figure 5 As shown in the pattern where the power-on switching speed F decreases with time t at a constant slope, the frequency of the power-on switching timing signal ST decreases with time t at a constant slope starting from time t2.

[0107] As other examples, such as Figure 6 As shown, when the storage unit 13 stores a speed control pattern in which the power-on switching speed F increases at a constant slope with time t, the frequency of the power-on switching timing signal ST increases at a constant slope with time t from time t2. Other examples include... Figure 7 As shown, when a speed control pattern in which the communication switching speed F decreases in stages with time t is stored in the storage unit 13, the frequency of the power-on switching timing signal ST decreases in stages with time t starting from time t2. Other examples include... Figure 8 As shown, when a speed control pattern in which the power-on switching speed F increases in stages with time t is stored in the storage unit 13, the frequency of the power-on switching timing signal ST increases in stages with time t from time t2.

[0108] The power-on control unit 15 switches the power-on pattern synchronously with the rising edge of the power-on switching timing signal ST. For example, as Figure 9 As shown, when a rising edge is generated in the power-on switching timing signal ST at time t2, the power-on control unit 15 first starts the switching control of each arm switch according to the power-on pattern PA4 that generates an appropriate rotating magnetic field for the phase of the motor 20 fixed by DC excitation control. That is, during the power-on period from time t2 until time t3 when the next rising edge of the power-on switching timing signal ST is generated, the upper arm switch Q of phase W...WH and U-phase lower side arm switch Q UL The circuit is switched on, and the remaining arm switches are switched off. During this energizing period, the upper arm switch Q of phase W is switched off. WH The switch duty cycle is controlled by the switch, which is determined by the control voltage VC that varies according to the voltage control pattern. Therefore, during this energizing period, the effective voltage value of the drive voltage V applied to the energized phase, i.e., the W-phase terminal voltage Vw, varies according to the voltage control pattern.

[0109] like Figure 9 As shown, when the next rising edge of the power-on switching timing signal ST is generated at time t3, the power-on control unit 15 switches the power-on pattern PA4 to the power-on pattern PA5, and starts the switching control of each arm switch according to the power-on pattern PA5. That is, during the power-on period from time t3 to time t4 when the next rising edge of the power-on switching timing signal ST is generated, the upper arm switch Q of phase V... VH and U-phase lower side arm switch Q UL The circuit is switched on, and the remaining arm switches are switched off. During this energizing period, the upper arm switch Q of phase V is switched off. VH The switch duty cycle is controlled by the switch, which is determined by the control voltage VC that varies according to the voltage control pattern. Therefore, the effective voltage value of the drive voltage V applied to the energized phase, i.e., the V-phase terminal voltage Vv, varies according to the voltage control pattern during this energizing period.

[0110] like Figure 9 As shown, when the next rising edge of the power-on switching timing signal ST is generated at time t4, the power-on control unit 15 switches the power-on pattern PA5 to the power-on pattern PA6, and starts the switching control of each arm switch according to the power-on pattern PA6. That is, during the power-on period from time t4 to time t5 when the next rising edge of the power-on switching timing signal ST is generated, the upper arm switch Q of phase V... VH and W-phase lower side arm switch Q WL The circuit is switched on, and the remaining arm switches are switched off. During this energizing period, the upper arm switch Q of phase V is switched off. VH The switch duty cycle is controlled by the switch, which is determined by the control voltage VC that varies according to the voltage control pattern. Therefore, the effective voltage value of the drive voltage V applied to the energized phase during this energizing period, i.e., the V-phase terminal voltage Vv, varies according to the voltage control pattern.

[0111] like Figure 9 As shown, when the next rising edge of the power-on switching timing signal ST is generated at time t5, the power-on control unit 15 switches the power-on pattern PA6 to the power-on pattern PA1, and starts the switching control of each arm switch according to the power-on pattern PA1. That is, during the power-on period from time t5 to time t6 when the next rising edge of the power-on switching timing signal ST is generated, the upper arm switch Q of phase U... UH and W-phase lower side arm switch QWL The circuit is switched on, and the remaining arm switches are switched off. During this energizing period, the upper arm switch Q of phase U is switched off. UH The switch duty cycle is controlled by the switch, which is determined by the control voltage VC that varies according to the voltage control pattern. Therefore, the effective voltage value of the drive voltage V applied to the energized phase, i.e., the U-phase terminal voltage Vu, varies according to the voltage control pattern during this energizing period.

[0112] like Figure 9 As shown, when the next rising edge of the power-on switching timing signal ST is generated at time t6, the power-on control unit 15 switches the power-on pattern PA1 to the power-on pattern PA2, and starts the switching control of each arm switch according to the power-on pattern PA2. That is, during the power-on period from time t6 to time t7 when the next rising edge of the power-on switching timing signal ST is generated, the upper arm switch Q of phase U... UH and V-phase lower side arm switch Q VL The circuit is switched on, and the remaining arm switches are switched off. During this energizing period, the upper arm switch Q of phase U is switched off. UH The switch duty cycle is controlled by the switch, which is determined by the control voltage VC that varies according to the voltage control pattern. Therefore, the effective voltage value of the drive voltage V applied to the energized phase, i.e., the U-phase terminal voltage Vu, varies according to the voltage control pattern during this energizing period.

[0113] like Figure 9 As shown, when the next rising edge of the power-on switching timing signal ST is generated at time t7, the power-on control unit 15 switches the power-on pattern PA2 to the power-on pattern PA3, and starts the switching control of each arm switch according to the power-on pattern PA3. That is, during the power-on period from time t7 to time t8 when the next rising edge of the power-on switching timing signal ST is generated, the upper arm switch Q of phase W... WH and V-phase lower side arm switch Q VL The circuit is switched on, and the remaining arm switches are switched off. During this energizing period, the upper arm switch Q of phase W is switched off. WH The switch duty cycle is controlled by the switch, which is determined by the control voltage VC that varies according to the voltage control pattern. Therefore, during this energizing period, the effective voltage value of the drive voltage V applied to the energized phase, i.e., the W-phase terminal voltage Vw, varies according to the voltage control pattern.

[0114] As described above, when the sensorless control device 10 operates in forced commutation mode, it performs forced commutation control as follows: While varying the drive voltage V applied to the energized phase of the motor 20 over time according to a predetermined voltage control pattern, it also varies the energization switching speed F according to a predetermined speed control pattern. During forced commutation control, the combination of the drive voltage V and the energization switching speed F at any given time always satisfies a linear function LF with a negative slope, where the drive voltage V and the energization switching speed F are variables.

[0115] For example, such as Figure 5 As shown, when the storage unit 13 stores a voltage control pattern in which the drive voltage V increases at a constant slope with time t and a speed control pattern in which the power-on switching speed F decreases at a constant slope with time t, after the forced commutation control starts at time t2, the drive voltage V applied to the energized phase of the motor 20 increases at a constant slope with time t according to the voltage control pattern, and the frequency of the power-on switching timing signal ST, i.e., the power-on switching speed F, decreases at a constant slope with time t according to the speed control pattern.

[0116] As other examples, such as Figure 6 As shown, when the storage unit 13 stores a voltage control pattern in which the drive voltage V decreases with time t at a constant slope and a speed control pattern in which the power-on switching speed F increases with time t at a constant slope, after the forced commutation control starts at time t2, the drive voltage V applied to the energized phase of the motor 20 decreases with time t at a constant slope according to the voltage control pattern, and the frequency of the power-on switching timing signal ST, i.e., the power-on switching speed F, increases with time t at a constant slope according to the speed control pattern.

[0117] As other examples, such as Figure 7 As shown, when the storage unit 13 stores a voltage control pattern in which the drive voltage V increases in stages with time t and a speed control pattern in which the power-on switching speed F decreases in stages with time t, after the forced commutation control starts at time t2, the drive voltage V applied to the energized phase of the motor 20 increases in stages with time t according to the voltage control pattern, and the frequency of the power-on switching timing signal ST, i.e., the power-on switching speed F, decreases in stages with time t according to the speed control pattern.

[0118] As other examples, such as Figure 8 As shown, when the storage unit 13 stores a voltage control pattern in which the drive voltage V decreases in stages with time t and a speed control pattern in which the power-on switching speed F increases in stages with time t, after the forced commutation control starts at time t2, the drive voltage V applied to the energized phase of the motor 20 decreases in stages with time t according to the voltage control pattern, and the frequency of the power-on switching timing signal ST, i.e., the power-on switching speed F, increases in stages with time t according to the speed control pattern.

[0119] In addition, Figures 5 to 8In any example, after the start of forced commutation control at time t2, the combination of drive voltage V and switching speed F at any time always satisfies a linear function LF with drive voltage V and switching speed F as variables and having a negative slope.

[0120] By performing the forced commutation control described above when starting the motor 20, the FV characteristic suitable for the combination of drive voltage V and energizing switching speed F varies with time within the range from the FV characteristic of load T1 to the FV characteristic of load T4. That is, the range of the FV characteristic of the motor 20 that can be stably controlled can be expanded, resulting in the motor 20 being able to stably rotate to a speed at which a back electromotive force that can be detected at a zero crossing point can be generated when starting the motor 20, regardless of the load size.

[0121] like Figure 9 As shown, before the motor 20 reaches the speed at which a detectable zero-crossing back electromotive force is generated, the zero-crossing detection signals Zu, Zv, and Zw are all at a low level, and the phase detection signals Hu, Hv, and Hw are also all at a low level. Here, it is assumed that at time t12, the motor 20 reaches the speed at which a detectable zero-crossing back electromotive force is generated.

[0122] When the motor 20 reaches the speed required to generate a detectable zero-crossing back electromotive force at time t12, the zero-crossing detection signals Zu, Zv, and Zw generate rising or falling edges synchronously with the timing of zero-crossing in the terminal voltages Vu, Vv, and Vw. As a result, after time t12, the phase detection signals Hu, Hv, and Hw generate rising or falling edges with a 30° phase delay relative to the zero-crossing detection signals Zu, Zv, and Zw.

[0123] like Figure 9 As shown, during the period from time t14 to time t20, the phase patterns identified based on the phase detection signals Hu, Hv, and Hw change in the order of PB4, PB5, PB6, PB1, PB2, and PB3. The voltage control unit 14 and the power-on control unit 15 monitor the state of the phase detection signals Hu, Hv, and Hw in the forced commutation mode. When they detect that the phase patterns identified based on the phase detection signals Hu, Hv, and Hw appear in the same order as the six phase patterns stored in the storage unit 13, they determine that the phase has been successfully identified based on the phase detection signals Hu, Hv, and Hw, and switch to the sensorless synchronous control mode. The voltage control unit 14 and the power-on control unit 15 switch to the sensorless synchronous control mode synchronously with the falling edge generated in the phase detection signal Hu at time t20.

[0124] After transitioning to the sensorless synchronous control mode at time t20, the voltage control unit 14 calculates the rotational speed of the motor 20 based on the phase detection signals Hu, Hv, and Hw. For example, the voltage control unit 14 measures the time between the falling edge generated in the phase detection signal Hu at time t20 and the rising edge generated in the phase detection signal Hw at time t19, i.e., the time it takes for the motor 20 to rotate 60°, and calculates the rotational speed of the motor 20 accordingly. The voltage control unit 14 determines the control voltage VC that makes the deviation between the calculated rotational speed and the target rotational speed represented by the control command signal CS zero through PI calculation, and outputs the determined control voltage VC to the power-on control unit 15.

[0125] When the system transitions to the sensorless synchronous control mode at time t20, the power-on control unit 15 stops generating the power-on switching timing signal ST and switches the power-on pattern synchronously with the edges generated in the phase detection signals Hu, Hv, and Hw. For example, the power-on control unit 15 switches the power-on pattern to power-on pattern PA4 synchronously with the falling edge generated in the phase detection signal Hu at time t20, and starts the switching control of each arm switch according to power-on pattern PA4.

[0126] That is, during the energizing period from time t20 to time t21 when the rising edge of the phase detection signal Hv is generated, the upper arm switch Q of phase W... WH and U-phase lower side arm switch Q UL The circuit is switched on, and the remaining arm switches are switched off. During this energizing period, the upper arm switch Q of phase W is switched off. WH The switching duty cycle, determined by the control voltage VC, is controlled by the switch. Therefore, the drive voltage V applied to the energized phase during this energizing period becomes a voltage value that makes the deviation between the calculated rotational speed and the target rotational speed zero. The energizing control unit 15 identifies the phase pattern PB4 during this energizing period based on the states of the phase detection signals Hu, Hv, and Hw. Based on the identified phase pattern PB4, the energizing control unit 15 determines the energizing pattern PA5 as the energizing pattern to be used in the next energizing period.

[0127] like Figure 9 As shown, when a rising edge is generated in the phase detection signal Hv at time t21, the voltage control unit 14 measures the time between this rising edge and the falling edge generated in the phase detection signal Hu at time t20, thereby calculating the rotational speed of the motor 20. The voltage control unit 14 determines the control voltage VC that makes the deviation between the calculated rotational speed and the target rotational speed represented by the control command signal CS zero through PI calculation, and outputs the determined control voltage VC to the power-on control unit 15.

[0128] When a rising edge is generated in the phase detection signal Hv at time t21, the power-on control unit 15 synchronously switches the power-on pattern to power-on pattern PA5, and starts the switching control of each arm switch according to power-on pattern PA5. That is, during the power-on period from time t21 to time t22 when a falling edge is generated in the phase detection signal Hw, the upper arm switch Q of phase V... VH and U-phase lower side arm switch Q UL The circuit is switched on, and the remaining arm switches are switched off. During this energizing period, the upper arm switch Q of phase V is switched off. VH The switch duty cycle, determined by the control voltage VC, is controlled by the switch. Therefore, the drive voltage V applied to the energized phase during this energizing period becomes a voltage value that makes the deviation between the calculated rotational speed and the target rotational speed zero. The energizing control unit 15 identifies the phase pattern PB5 during this energizing period based on the states of the phase detection signals Hu, Hv, and Hw. Based on the identified phase pattern PB5, the energizing control unit 15 determines the energizing pattern PA6 as the energizing pattern to be used in the next energizing period.

[0129] As described above, when the sensorless control device 10 operates in sensorless synchronous control mode, it synchronously identifies the phase pattern, determines the energizing pattern, and switches the energizing pattern with the phase detection signals Hu, Hv, and Hw generated using the back electromotive force generated in the motor 20. This allows for energizing control of the motor 20 without using position sensors such as Hall sensors. By performing this sensorless synchronous control, the rotational speed of the motor 20 is maintained at the target rotational speed indicated by the control command signal CS. Furthermore, the energizing switching speed F in the sensorless synchronous control is automatically controlled based on the timing of edge generation in the phase detection signals Hu, Hv, and Hw.

[0130] As described above, in this embodiment, when starting the motor 20, if the phase of the motor 20 cannot be identified, forced commutation control is performed. In this forced commutation control, the drive voltage V applied to the energized phase of the motor 20 is varied over time according to a predetermined voltage control pattern, and the energization switching speed F is varied according to a predetermined speed control pattern. During the forced commutation control, the combination of the drive voltage V and the energization switching speed F at any given time always satisfies a linear function LF with a negative slope, where the drive voltage V and the energization switching speed F are variables.

[0131] By performing the forced commutation control described above when starting the motor 20, the range of stable controllable FV characteristics of the motor 20 can be expanded. As a result, the motor 20 can be stably rotated to a speed at which a detectable back electromotive force is generated when starting the motor 20, regardless of the load size. Therefore, according to this embodiment, the motor 20 can be successfully started regardless of the load size through sensorless control.

[0132] In this embodiment, as an example of the forced commutation control described above, the driving voltage V applied to the energized phase of the motor 20 is increased with time at a constant slope according to a predetermined voltage control pattern, while the energization switching speed F is decreased with time at a constant slope according to a predetermined speed control pattern.

[0133] Furthermore, in this embodiment, as another example of the forced commutation control described above, while the drive voltage V applied to the energized phase of the motor 20 decreases with time at a constant slope according to a predetermined voltage control pattern, the energization switching speed F increases with time at a constant slope according to a predetermined speed control pattern.

[0134] By implementing forced commutation control according to these two examples, the range of the FV characteristics of motor 20 can be stably controlled to vary linearly. As a result, the possibility of driving motor 20 according to the combination of drive voltage V and energizing switching speed F that is actually suitable for the FV characteristics of the load connected to motor 20 is increased, and motor 20 can be rotated more stably to a speed that generates a detectable back EMF when starting motor 20.

[0135] In this embodiment, as another example of the forced commutation control described above, the drive voltage V applied to the energized phase of the motor 20 is increased in stages over time according to a predetermined voltage control pattern, while the energization switching speed F is decreased in stages over time according to a predetermined speed control pattern.

[0136] Furthermore, in this embodiment, as another example of the forced commutation control described above, the drive voltage V applied to the energized phase of the motor 20 is gradually reduced over time according to a predetermined voltage control pattern, while the energization switching speed F is gradually increased over time according to a predetermined speed control pattern.

[0137] By performing forced commutation control according to these two examples, the range of FV characteristics of motor 20 can be stably controlled to change in stages. As a result, compared with the two examples above where the range of FV characteristics changes linearly, although the possibility of driving motor 20 according to the combination of drive voltage V and energizing switching speed F that is actually suitable for the FV characteristics of the load connected to motor 20 is reduced, the processing load of energizing control can be reduced.

[0138] Furthermore, in this embodiment, DC excitation control is performed before forced commutation control when starting the motor 20. Therefore, the phase of the motor 20 is fixed at a specific phase before forced commutation control is performed, thus enabling the motor 20 to start rotating smoothly when forced commutation control begins.

[0139] Furthermore, in this embodiment, sensorless synchronization control is performed after the motor 20 reaches a speed that generates a detectable back electromotive force during forced commutation control. Thus, without using position sensors such as Hall sensors, the motor 20's rotational speed can be controlled to the target rotational speed indicated by the control command signal CS input from the host control device 400.

[0140] [Variation Example]

[0141] This invention is not limited to the above-described embodiments. The various structures described in this specification can be appropriately combined within a range that does not contradict each other.

[0142] For example, in the above embodiments, examples of voltage control patterns include a pattern in which the driving voltage increases with time at a constant slope, a pattern in which the driving voltage decreases with time at a constant slope, a pattern in which the driving voltage increases periodically with time, and a pattern in which the driving voltage decreases periodically with time. Furthermore, in the above embodiments, examples of speed control patterns include a pattern in which the energizing switching speed increases with time at a constant slope, a pattern in which the energizing switching speed decreases with time at a constant slope, a pattern in which the energizing switching speed increases periodically with time, and a pattern in which the energizing switching speed decreases periodically with time. The voltage control pattern and speed control pattern of the present invention are not limited to these; any other pattern can be used as long as the condition that "the combination of the driving voltage V and the energizing switching speed F at any given time always satisfies a linear function with the driving voltage V and the energizing switching speed F as variables and having a negative slope" is met.

[0143] Furthermore, in the above embodiments, a sensorless 120° power-on method was exemplified as a sensorless control method, but the sensorless control method in this invention is not limited to the sensorless 120° power-on method. Any control method that does not use a position sensor can be used, and other methods such as the 180° power-on method can also be used.

[0144] Furthermore, in the above embodiment, a case is illustrated where DC excitation control is performed before forced commutation control when starting the motor 20, but DC excitation control is not always necessary.

Claims

1. A sensorless control device for controlling a motor without a position sensor, wherein, This sensorless control device has the following features: The motor drive circuit consists of multiple phase switching elements that provide power to each phase of the motor. The phase detection unit detects the phase of the motor based on the back electromotive force of the motor and outputs a phase detection signal representing the detection result of the phase. The storage unit stores a voltage control pattern and a speed control pattern. The voltage control pattern represents a control pattern for the drive voltage applied to the energized phase of the motor, and the speed control pattern represents a control pattern for the energization switching speed, which is the speed at which the energized phase is switched. The voltage control unit outputs a control voltage based on the control command signal input from the upper control device, the phase detection signal, and the voltage control pattern; as well as The power-on control unit controls the switching elements of the motor drive circuit based on the control voltage, the phase detection signal, and the speed control pattern, thereby controlling the drive voltage and the power-on switching speed. When starting the motor, if the phase cannot be identified based on the phase detection signal, the voltage control unit increases the control voltage over time according to the voltage control pattern, and the energizing control unit controls the switching element according to the control voltage and the speed control pattern, thereby performing forced commutation control as follows: while increasing the drive voltage over time in sync with the control voltage, the energizing switching speed decreases over time according to the speed control pattern, so that when starting the motor, the motor can be stably rotated to a speed at which a detectable zero-crossing back electromotive force is generated regardless of the load size. During the forced commutation control, the combination of the drive voltage and the energizing switching speed at any given time always satisfies a linear function with a negative slope, using the drive voltage and the energizing switching speed as variables.

2. The sensorless control device according to claim 1, wherein, The voltage control unit increases the control voltage at a constant slope over time according to the voltage control pattern. The power-on control unit controls the switching element according to the control voltage and the speed control pattern, thereby performing forced commutation control as follows: while increasing the drive voltage at a constant slope over time in sync with the control voltage, the power-on switching speed decreases at a constant slope over time according to the speed control pattern.

3. The sensorless control device according to claim 1, wherein, The voltage control unit increases the control voltage in stages over time according to the voltage control pattern. The power-on control unit controls the switching element according to the control voltage and the speed control pattern, thereby performing forced commutation control as follows: while synchronously increasing the drive voltage with time in sync with the control voltage, the power-on switching speed is decreased with time in sync with the speed control pattern.

4. The sensorless control device according to any one of claims 1 to 3, wherein, The storage unit pre-stores the DC excitation conditions under which the motor's phase is fixed at a specific phase. When the motor is started, if the phase cannot be identified according to the phase detection signal, the voltage control unit outputs the control voltage according to the DC excitation condition before outputting the control voltage according to the voltage control pattern. The power-on control unit controls the switching element according to the control voltage and the DC excitation condition, thereby applying a DC drive voltage for a certain period of time to a specific energized phase.

5. The sensorless control device according to any one of claims 1 to 3, wherein, When the phase is successfully identified based on the phase detection signal, the voltage control unit outputs the control voltage based on the control command signal and the phase detection signal, and the power-on control unit controls the switching element based on the control voltage and the phase detection signal, thereby applying a drive voltage corresponding to the control command signal to the power-on phase and switching the power-on phase at a power-on switching speed determined by the phase detection signal.

6. An electric oil pump device, comprising: A motor, which has a shaft; A pump, located on one axial side of the shaft, is driven by the motor via the shaft to spray oil; and The sensorless control device according to any one of claims 1 to 4 controls the motor without a position sensor.

7. A sensorless control method for controlling a motor without a position sensor, wherein, When starting the motor, if the phase of the motor cannot be identified, forced commutation control is performed as follows: while increasing the drive voltage applied to the energized phase of the motor over time according to a predetermined voltage control pattern, the switching speed of the energized phase is decreased over time according to a predetermined speed control pattern, so that the motor can be stably rotated to a speed at which a detectable zero-crossing back electromotive force is generated when starting the motor, regardless of the load size. During the forced commutation control, the combination of the drive voltage and the energizing switching speed at any given time always satisfies a linear function with a negative slope, using the drive voltage and the energizing switching speed as variables.

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