JP2018098861A - Driving device and driving method of brushless motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving device and a driving method of a brushless motor capable of improving stability of current control for the brushless motor.SOLUTION: The driving device of a brushless motor for performing feedback control so that a phase current of the brushless motor becomes a phase current target value which is a target value of the phase current, includes: a current detection unit that detects a power supply current value which is a current value of a power supply current supplied from a power supply device; an inverter unit having a switching element and converting the power supply current into the phase current by performing PWM control of on and off of the switching element; and a control unit that controls a duty ratio of the PWM control according to a power supply current value fed back from the current detection unit. When the power supply current value fed back is within a predetermined detectable range, the control unit controls a duty ratio to a constant value.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a driving device and a driving method for a brushless motor.

  Conventionally, a brushless motor drive device converts a power supply current supplied from a power supply device into an alternating current by PWM (Pulse Width Modulation) control, and outputs the alternating current as a phase current to each phase of the brushless motor. By doing so, the brushless motor is driven (see Patent Document 1).

  Here, the brushless motor drive device includes a current detection unit that detects a current value of a power supply current supplied from the power supply device (hereinafter referred to as “power supply current value”), and the power supply detected by the current detection unit. Based on the current value and the duty ratio of PWM control, the current value of the phase current (hereinafter referred to as “phase current value”) is estimated. The brushless motor driving apparatus controls the duty ratio of the PWM control so that the estimated phase current value becomes the target value. As described above, the brushless motor driving device performs current control on the driving of the brushless motor by feeding back the estimated phase current value to the target value.

JP-A-2015-35858

  However, in the above-described current detection unit, a minimum current value (hereinafter referred to as “current threshold”) that can be detected correctly is determined. Therefore, when the current value of the power supply current supplied from the power supply device is less than the current threshold value, the power supply current value detected by the current detection unit is indefinite and may not be an accurate value. Therefore, the phase current value cannot be estimated correctly, and the current control for the brushless motor is not stable. Such a problem is not limited to the case where the estimated phase current is feedback-controlled, but is a problem common to all current feedback controls when the brushless motor is current-controlled.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a brushless motor driving apparatus and a driving method capable of improving the stability of current control for the brushless motor.

  One aspect of the present invention is a brushless motor driving apparatus that performs feedback control so that a phase current of a brushless motor becomes a phase current target value that is a target value of the phase current, and is supplied from a power supply apparatus. A current detection unit that detects a power supply current value that is a current value of the power supply current, and an inverter unit that has a switching element and converts the power supply current into the phase current by PWM control of on / off of the switching element And a control unit that controls a duty ratio of the PWM control according to a power supply current value fed back from the current detection unit, wherein the control unit detects the power supply current value fed back as a predetermined value. When not in a possible range, the brushless motor drive device is characterized in that the duty ratio is controlled to a constant value.

  One embodiment of the present invention is the above-described brushless motor driving device, wherein the detectable range is a range of current values that can be accurately detected by the current detection unit.

  One aspect of the present invention is the above-described brushless motor drive device, wherein the control unit is an estimated phase current value that is an estimated value of the phase current according to the power supply current value and the duty ratio to be fed back. And an feedback control unit that feedback-controls the duty ratio so that the phase current estimated value becomes the phase current target value, and the feedback control unit includes the power supply current value and When the phase current target value is not within the detectable range, a first control unit that performs first control for controlling the duty ratio to a constant value, and when the power supply current value is not within the detectable range. And when the phase current target value is within the detectable range, a second control unit that performs a second control for increasing the duty ratio every predetermined time.

  One aspect of the present invention is the above-described brushless motor driving device, wherein the feedback control unit includes the phase current estimated value, the phase current target value, and the phase current target value when the power supply current value is in the detectable range. The brushless motor driving device according to claim 3, further comprising a PI control unit configured to control the duty ratio by performing PI control so that a difference value of the two becomes a predetermined value.

  One aspect of the present invention is the above-described brushless motor driving device, wherein the PI control unit is configured to integrate the PI control when the PI control is shifted from the first control or the second control to the PI control. The initial value is determined based on the duty ratio immediately before the transition.

One aspect of the present invention is the brushless motor driving device described above, wherein an initial value of an integral value for the PI control is calculated by the following equation (1).
Initial value of integral value = {duty ratio before transition− (phase current target value−phase current estimated value) × proportional control gain} / integral control gain (1)

  One embodiment of the present invention is the above-described brushless motor driving device, wherein the brushless motor is a driving source of an electric oil pump.

  One aspect of the present invention is a method for driving a brushless motor, wherein feedback control is performed so that a phase current of the brushless motor becomes a phase current target value that is a target value of the phase current, which is supplied from a power supply device. A current detection step for detecting a power supply current value that is a current value of the power supply current, and a switching element, and PWM control of on and off of the switching element to convert the power supply current into the phase current, An output step for outputting the phase current to a brushless motor; and a control step for controlling a duty ratio of the PWM control in accordance with a power supply current value fed back from the current detection step. When the power supply current value fed back is not within a predetermined detectable range, the duty ratio is controlled to a constant value. Characterized the door, it is a driving method of a brushless motor.

  As described above, according to the present invention, it is possible to improve the stability of current control for a brushless motor.

FIG. 2 is a diagram illustrating an example of a schematic configuration of the electric oil pump 1 when the driving device 7 of the brushless motor 6 according to the first embodiment is used for driving the electric oil pump 1. It is a figure which shows an example of schematic structure of the drive device 7 which concerns on 1st Embodiment. It is a figure which shows an example of schematic structure of the control part 11 which concerns on 1st Embodiment. It is a figure which shows an example of schematic structure of the PI control part 115 which concerns on 1st Embodiment. It is a time chart figure of the current feedback control in the conventional drive device. It is a time chart figure of current feedback control using the 1st control in drive device 7 concerning a 1st embodiment. It is a figure which shows the flow of the 1st control of the drive device 7 which concerns on 1st Embodiment. It is a figure which shows an example of schematic structure of the drive device 7A which concerns on 2nd Embodiment. It is a figure which shows an example of schematic structure of 11 A of control parts which concern on 2nd Embodiment. It is a time chart figure of current feedback control in drive device 7A concerning a 2nd embodiment. It is a figure which shows the flow of control of the duty ratio D in the drive device 7A which concerns on 2nd Embodiment. It is a figure which shows an example of schematic structure of the drive device 7B which concerns on 3rd Embodiment. It is a figure which shows an example of schematic structure of the control part 11B which concerns on 3rd Embodiment. It is a figure which shows the negative of the control part 11B which concerns on 2nd Embodiment. It is a time chart figure of current feedback control in drive device 7B concerning a 3rd embodiment. It is a figure which shows the flow of control of the duty ratio D in the drive device 7B which concerns on 3rd Embodiment.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention. In the drawings, the same or similar parts may be denoted by the same reference numerals and redundant description may be omitted. In addition, the shape and size of elements in the drawings may be exaggerated for a clearer description.

  In the entire specification, when a part includes a component, “includes”, “have”, or “comprises”, this does not exclude other components unless otherwise stated. This means that it can further include the following components.

  Hereinafter, a brushless motor driving apparatus according to an embodiment of the present invention will be described with reference to the drawings.

  The brushless motor drive device according to the embodiment of the present invention drives the drive source of the electric pump using, for example, the brushless motor as a drive source of the electric oil pump. In the embodiment described below, a case where a brushless motor is used as a drive source of an electric oil pump will be described, but the present invention is not limited to this. For example, the brushless motor can be used as a drive source for a wiper device, an electric power steering device, or the like.

(First embodiment)
FIG. 1 is a diagram illustrating an example of a schematic configuration of the electric oil pump 1 when the driving device 7 of the brushless motor 6 according to the first embodiment is used for driving the electric oil pump 1.
The electric oil pump 1 is used as a hydraulic supply source that supplies oil to an oil supply destination 8 such as a hydraulic device such as a continuously variable transmission mounted on a vehicle.
The electric oil pump 1 is connected to the host ECU 2.
The electric oil pump 1 pumps up oil stored in the oil pan 3 and supplies the hydraulic equipment with hydraulic pressure.

The host ECU 2 is connected to the electric oil pump 1 and the temperature sensor 4.
The host ECU 2 acquires the oil temperature measured by the temperature sensor 4 (hereinafter referred to as “measured oil temperature”). When the host ECU 2 acquires the measured oil temperature, the host ECU 2 refers to an oil temperature table stored in advance in a storage unit (not shown) in the host ECU 2 and refers to the phase current that flows through the brushless motor 6 corresponding to the measured oil temperature. Target value (hereinafter referred to as “phase current target value”) I _pth . For example, the oil temperature table is a table in which the oil temperature is associated with the phase current target value I _pth for each oil temperature.
The _host ECU 2 _{outputs the} phase current target value I _pth acquired from the oil temperature table to the electric oil pump 1 as a command value.

Next, the electric oil pump 1 will be described.
The electric oil pump 1 includes an oil pump 5, a brushless motor 6, a driving device 7, and a rotation sensor 10.

  The oil pump 5 is connected to the brushless motor 6 and the oil supply destination 8. The oil pump 5 is a pump driven by a brushless motor 6. The oil pump 5 is driven by the brushless motor 6 to pump the oil in the oil pan 3 to the oil supply destination 8.

  The brushless motor 6 includes a rotor having permanent magnets and a stator on which coils U, V, and W corresponding to three phases (U, V, and W) are wound in order in the rotation direction of the rotor. Each of the coils U, V, W of each phase has one end connected to the drive device 7 via a motor terminal and the other end connected to each other.

The drive device 7 is connected to the host ECU 2 and the brushless motor 6. The drive device 7 controls the drive of the brushless motor 6 based on the phase current target value I _pth output from the _host ECU 2. Specifically, the drive device 7 performs feedback control so that the phase current of the brushless motor 6 becomes the phase current target value I _pth input from the _host ECU 2. For example, the drive device 7 converts a current supplied from the power supply device 9 (hereinafter referred to as “power supply current”) into a predetermined current (for example, AC current), and uses the converted current as a phase current to the brushless motor 6. Output.

  The rotation sensor 10 detects the rotation of the brushless motor 6. For example, the rotation sensor 10 is a magnetic rotary encoder provided with a Hall IC. For example, the rotation sensor 10 detects a change in magnetic flux density received from a sensor magnet (not shown) provided in the rotor of the brushless motor 6. The rotation sensor 10 generates detection signals of two phases (A phase and B phase) having different phases from each other using the detected change in magnetic flux density as an electrical signal. The rotation sensor 10 outputs an output value depending on whether or not the value of the alternating signal for each phase exceeds a preset value (that is, the strength of the magnetic field received by the rotation sensor 10 exceeds a predetermined strength). It is converted into a binary digital signal (pulse signal) that changes between High and Low. The rotation sensor 10 outputs an A-phase pulse signal and a B-phase pulse signal as detection signals to the driving device 7 as pulse signals of each phase.

Below, the drive device 7 which concerns on 1st Embodiment is demonstrated.
FIG. 2 is a diagram illustrating an example of a schematic configuration of the driving device 7 according to the first embodiment.
As shown in FIG. 2, the drive device 7 includes a control unit 11, an inverter unit 12, a current detection unit 13, and a gate driver circuit 16.

The inverter unit 12 has a plurality of switching elements, and converts the power source current into a phase current by PWM (Pulse Width Modulation) control of on / off of the switching elements. Specifically, the inverter unit 12 includes six switching elements 121 to 126 as shown in FIG. The inverter unit 12 switches on and off the switching elements 121 to 126 to convert the power source current into the phase current.
The switching elements 121 and 122 connected in series, the switching elements 123 and 124 connected in series, and the switching elements 125 and 126 connected in series are connected to the power supply device 9 connected via the current detection unit 13. Are connected in parallel between the high potential side and the ground potential.

  The connection point between the switching element 121 and the switching element 122 is connected to one end of the coil U. A connection point between the switching element 123 and the switching element 124 is connected to one end of the coil V. A connection point between the switching element 125 and the switching element 126 is connected to one end of the coil W.

  The switching elements 121 to 126 are, for example, FETs (Field Effective Transistors) or IGBTs (Insulated Gate Bipolar Transistors). Each switching element 121-126 has the structure connected in parallel with the free-wheeling diode 131-136. The switching elements 121 to 126 are switched on and off based on a pulse width modulation signal (PWM signal) input from the control unit 11 via the gate driver circuit 16.

  The gate driver circuit 16 outputs the PWM signal having the duty ratio D output from the control unit 11 to the switching elements 121 to 126.

Current detector 13 detects the power source current value I _b is a current value of the power supply current supplied from the power supply 9. For example, the current detection unit 13 includes a shunt resistor 14 and an amplifier AM.
The amplifier AM amplifies a voltage difference generated at both ends of the shunt resistor 14 when a power supply current flowing from the power supply device 9 to the inverter unit 12 flows to the shunt resistor 14. Then, the amplifier AM outputs a signal obtained by amplifying the voltage difference generated across the shunt resistor 14 to the control unit 11 as a current detection signal. The current detection signal indicates a power source current value I _b. In other words, the current detection unit 13 calculates the power current I _b from the potential difference generated across the shunt resistor 14, and outputs a power current I _b with the calculated the control unit 11.

Here, the current detection unit 13 has a detectable range that is a range of current values that can be accurately detected. For example, the detectable range is a current value range equal to or greater than a predetermined current threshold value I _bth . For example, the current threshold value I _bth is a minimum current value that can be correctly detected in the current detection unit 13. Therefore, when the power supply current value I _b supplied from the power supply unit 9 is less than the current threshold I _bth, the power supply current value I _b for the current detection unit 13 has detected is undefined and may not be the exact value . The detectable range may be set as a range of current values between the maximum current value that can be detected correctly and the minimum current value.

Current detector 13 outputs to the control unit 11 the supply current I _b detected every predetermined period.
In other words, the current detection unit 13 feeds back the power supply current value _Ib to the control unit 11.

  In the present embodiment, the case where the current detection unit 13 is connected between the power supply device 9 and the inverter unit 12 will be described, but the present invention is not limited thereto. For example, the current detection unit 13 may be connected between the inverter unit 12 and the ground potential.

Control unit 11, according to the power supply current value I _b fed back from the current detection unit 13, controls the duty ratio D of the PWM control of the inverter unit 12.
Below, an example of schematic structure of the control part 11 which concerns on 1st Embodiment is demonstrated.
FIG. 3 is a diagram illustrating an example of a schematic configuration of the control unit 11 according to the first embodiment.
As illustrated in FIG. 3, the control unit 11 according to the first embodiment includes a determination unit 112, an estimation unit 113, and a feedback control unit 114.

Determination unit 112 acquires the power current _{I b} from the current detection unit 13. Then, the determination unit 112 determines whether or not the power source current value I _b obtained from the current detector 13 is in the detectable range. Determination unit 112, when the power source current value I _b obtained from the current detector 13 has determined to be in the detectable range, the estimation unit an accurate signal indicating that the power supply current value I _b is a correct value 113 and the feedback control unit 114. On the other hand, the determination unit 112, when the power source current value I _b obtained from the current detection unit 13 determines that there is no detectable range (is outside the detectable range) is incorrect the power supply current value I _b An inaccurate signal indicating a value is output to the estimation unit 113 and the feedback control unit 114.

When the estimation unit 113 acquires an accurate signal from the determination unit 112, the phase current estimation value that is an estimation value of the phase current according to the power supply current value _Ib and the duty ratio D fed back from the current detection unit 13. I _pp is calculated. In other words, when the estimation unit 113 acquires an accurate signal from the determination unit 112, the estimation unit 113 estimates the current phase current according to the power supply current value _Ib and the duty ratio D. For example, the estimation unit 113 calculates the phase current estimated value I _pp (I _b / D) by dividing the power supply current value I _b by the duty ratio D. Note that the duty ratio D used for estimating the phase current is the current duty ratio D in the PWM control for controlling on and off of the switching elements 121 to 126 (the duty ratio D output from the control unit 11 to the gate driver circuit 16). ). Note that when the inaccurate signal is acquired from the determination unit 112, the estimation unit 113 does not calculate the phase current estimation value _Ipp .

As shown in FIG. 3, the feedback control unit 114 includes a PI control unit 115, a first control unit 116, and a storage unit 117.
PI control unit 115 controls the duty ratio D when the power source current value I _b to be fed back is in the detectable range. Specifically, PI control unit 115 controls duty ratio D of PWM control according to phase current estimated value I _pp when an accurate signal is acquired from determination unit 112.

For example, PI control unit 115, when the power supply current value I _b is in the detection range, the phase current estimated value difference value is a predetermined value of I _pp and the phase current target value I _pth (e.g., 0) becomes as The duty ratio D is controlled by PI control.
FIG. 4 is a diagram illustrating an example of a schematic configuration of the PI control unit 115 according to the first embodiment.

As shown in FIG. 4, the PI control unit 115 includes a subtractor 211, adders 212 and 215, and multipliers 213 and 214.
The subtractor 211 subtracts the phase current estimated value I _pp from the phase current target value I _ppth, and _outputs the phase current deviation ΔI _p (I _pth −I _pp ), which is the subtracted value, to the adder 212 and the multiplier 213. To do.
The adder 212 outputs a value obtained by adding the phase current deviation ΔI _p and the previous integrated value to the multiplier 214 as a new integrated value. Therefore, the adder 212, each time the PI control, and outputs an integral value obtained by adding the integral value of the phase current deviation [Delta] I _p up to the previous to a new phase current deviation [Delta] I _p to the multiplier 214. In the first embodiment, the initial value of the previous integral value is zero.

Multiplier 213 multiplies phase current deviation ΔI _p output from subtractor 211 by proportional control gain Kp, and outputs the multiplied value (ΔI _p × Kp) to adder 215.
Multiplier 214 multiplies the integral value output from adder 212 by integral control gain Ki, and outputs the multiplied value (integral value × Ki) to adder 215.
The adder 215 adds the value (ΔI _p × Kp) output from the multiplier 213 and the value (integral value × Ki) output from the multiplier 214 to add a duty ratio D (ΔI _p × Kp + integration). Value x Ki) is calculated. The adder 215 outputs the calculated duty ratio D to the gate driver circuit 16. Further, the adder 215 outputs the calculated duty ratio D to the estimation unit 113.

Returning to Figure 3, the first control unit 116, the power supply current value I _b which is fed back to control the duty ratio D in the absence in the detectable range. Specifically, when the inaccurate signal is acquired from the determination unit 112, the first control unit 116 controls the duty ratio D to a constant value. The value of the duty ratio D to be a constant value is stored in the storage unit 117. For example, the duty ratio D stored in the storage unit 117 is the previous duty ratio D. That is, the first control unit 116, when the power supply current value I _b that is fed back is shifted to outside the detection range of the detection range outputs the duty ratio D of the transition immediately before always to the gate driver circuit 16 .
Here, the effect of controlling the duty ratio D in the first control unit 116 to a constant value will be described with reference to FIGS. Hereinafter, the control for controlling the duty ratio D in the first control unit 116 to a constant value may be referred to as a first control.

  FIG. 5 is a time chart of current feedback control in a conventional drive device. FIG. 6 is a time chart of current feedback control using the first control in the driving device 7 according to the first embodiment.

As shown in FIG. 5, the conventional drive device controls the duty ratio D by _performing PI control so that the phase current deviation ΔI _p (I _pth −I _pp ) becomes zero. In this case, if the current value of the power supply current flowing from the power supply 9 to the inverter section 12 is less than the current threshold I _bth, the power supply current value I _b for the current detection unit 13 detects are not exact value indeterminate . That is, the power supply current value I _b is less than the current threshold I _bth is not an exact value undefined. In this case, even if the conventional drive device is controlled by performing PI control of the duty ratio D when the phase current deviation ΔI _p becomes 0, the value of the power supply current value I _b is indefinite and not accurate. The value of this phase current deviation ΔI _p is also indefinite, and the duty ratio D is not stable. Therefore, the phase current of the brushless motor 6 is not stabilized and may oscillate.

On the other hand, as shown in FIG. 6, the drive device 7 according to the first embodiment, when the supply current value I _b for the current detection unit 13 detects less than the current threshold I _bth is the duty ratio D constant Control to value. Thus, the driving device 7, it becomes possible to control the duty ratio D without the influence of the power source current value I _b is incorrect value undefined, the phase current of the brushless motor 6 is stabilized. Thereby, the stability of the current control for the brushless motor 6 is improved.

Below, the flow of 1st control of the drive device 7 which concerns on 1st Embodiment is demonstrated. FIG. 7 is a diagram illustrating a flow of the first control of the driving device 7 according to the first embodiment.
Determination unit 112 acquires the power current _{I b} from the current detection unit 13. Then, the determination unit 112, the power supply current value _{I b} obtained from the current detection unit 13 determines whether a current threshold _{I bth} more (step S101). Determination unit 112, when the power supply current value _{I b} obtained from the current detector 13 is determined to be current threshold _{I bth} more outputs an accurate signal to the estimating unit 113 and PI control unit 115.

PI control unit 115, when acquiring the correct signal from the judging unit 112, the estimation unit 113 phase current estimated values were calculated _{I pp} and the phase current target value _I phase current deviation which is subtracted value between _pth [Delta] I _p The duty ratio D is determined by performing PI control based on (I _pth −I _pp ) (step S102). Then, the PI control unit 115 outputs the determined duty ratio D to the gate driver circuit 16.

On the other hand, the determination unit 112, when the power supply current value I _b obtained from the current detection unit 13 is determined not to be current threshold I _bth more outputs an incorrect signal to the estimating unit 113 and the first control unit 116.
If the inaccurate signal is acquired from the determination unit 112, the first control unit 116 controls the duty ratio D to a constant value (step S103). For example, the first control unit 116 fixes the duty ratio D to the previous duty ratio D, and always outputs the fixed duty ratio D to the gate driver circuit 16. Here, for example, always from the power supply current value I _b is determined to be less than the current threshold value I _bth, it is until the power source current value I _b is determined to be current threshold I _bth more .

As described above, the drive device 7 according to the first embodiment is a drive device for the brushless motor 6 that _performs feedback control so that the phase current of the brushless motor 6 becomes the phase current target value I _pth . The driving device 7, the power supply current value I _b fed back from the current detection unit 13 when not in the detectable range, and controlling the duty ratio D to a constant value. Thereby, the drive device 7 can improve the stability of the current control for the brushless motor even when the power supply current _Ib is outside the detectable range and becomes unstable.

As described above, the driving device 7 according to the first embodiment switches between the PI control and the first control depending on whether or not the power supply current value _Ib is within the detectable range. That is, when the power supply current value _Ib is in the detectable range, the driving device 7 controls the phase current by controlling the duty ratio D by PI control, and the power supply current value _Ib is not in the detectable range. In this case, the phase current is controlled by setting the duty ratio D to a constant value by the first control.

(Second Embodiment)
Below, the drive device 7A of the brushless motor 6 which concerns on 2nd Embodiment is demonstrated.
FIG. 8 is a diagram illustrating an example of a schematic configuration of a driving device 7A according to the second embodiment.
As illustrated in FIG. 8, the drive device 7A includes a control unit 11A, an inverter unit 12, a current detection unit 13, and a gate driver circuit 16.

  FIG. 9 is a diagram illustrating an example of a schematic configuration of the control unit 11A according to the second embodiment. As illustrated in FIG. 9, the control unit 11A according to the second embodiment includes a determination unit 112A, an estimation unit 113, and a feedback control unit 114A.

Determination unit 112A determines whether or not the power source current value I _b obtained from the current detector 13 is in the detectable range. Further, determination unit 112A determines whether or not phase current target value I _pth input from _host ECU 2 is within a detectable range.

Determination unit 112A, when the power supply current value I _b obtained from the current detector 13 has determined to be in the detectable range outputs a correct signal to the estimating unit 113 and a feedback control unit 114A.
If the determination unit 112A determines that the power supply current value _Ib and the phase current target value _Ipth are not within the detectable range, the feedback control unit 114A outputs a first control signal that instructs execution of the first control. Output to.
If the determination unit 112A determines that the power supply current value _Ib is not in the detectable range and the phase current target value _Ipth is in the detectable range, the determination unit 112A instructs to perform the second control. The control signal is output to the feedback control unit 114A. Here, the second control is a control for increasing the duty ratio D every predetermined time.

As shown in FIG. 9, the feedback control unit 114 </ b> A includes a PI control unit 115, a PI control unit 115, a first control unit 116, a second control unit 118, and a storage unit 117.
The PI control unit 115 is a subtraction value between the phase current estimated value I _pp calculated by the estimation unit 113 and the phase current target value I _pth when the power supply current value I _b fed back is within the detectable range. The duty ratio D is determined by performing PI control based on the phase current deviation ΔI _p (I _pth −I _pp ).

The first control unit 116 controls the duty ratio D and the power source current value I _b fed back, when the phase current target value I _pth input from the high-level ECU is not in the detectable range together. Specifically, when acquiring the first control signal from the determination unit 112, the first control unit 116 controls the duty ratio D to a constant value. The value of the duty ratio D to be a constant value is stored in the storage unit 117. For example, the duty ratio D stored in the storage unit 117 is the previous duty ratio D.

The second control unit 118 is not the power source current value I _b is detectable range to be fed back, and the phase current target value I _pth output from the high-level ECU controls the duty ratio D in the case where the detection range . Specifically, when the second control unit 118 acquires the second control signal from the determination unit 112, the second control unit 118 increases the duty ratio D every predetermined time. For example, the second control unit 118, when the power supply current value I _b to be fed back is a case not in the detectable range, the phase current target value I _pth shifts to the detectable range outside the detectable range, The duty ratio is increased from the duty ratio D in the first control every predetermined time. Thus, drive devices 7A, when the power source current value I _b to be fed back is in the outside of the detection range, the phase current target value I _pth has shifted within the detectable range outside the detectable range, the Transition from the first control to the second control.

  Here, the effect of increasing the duty ratio D in the second control unit 118 every predetermined time will be described with reference to FIG. FIG. 10 is a time chart of current feedback control in the drive device 7A according to the second embodiment.

For example, in the driving device 7 according to the first embodiment, when the power supply current value _Ib is less than the current threshold value _Ibth , the duty ratio D is set to a constant value, thereby stabilizing the current control for the brushless motor. Can be improved. However, in the driving device 7, the phase current may not increase due to the duty ratio D being controlled to a constant value, and as a result, the power supply current value _Ib may not increase. Therefore, the drive device 7 may not be able to increase the phase current even when the phase current target value I _pth that increases the phase current from the upper ECU 2 _{beyond the} current threshold value I _bth is input to the drive device 7. .

On the other hand, drive system 7A according to the second embodiment, when the power source current value I _b and the phase current target value I _pth is less than the current threshold I _bth is first control for the duty ratio D to a constant value I do. The drive device 7A according to the second embodiment has a duty ratio D when the power supply current value _Ib is less than the current threshold value _Ibth and the phase current target value _Ipth is _{equal to} or greater than the current threshold value _Ibth. The second control for increasing is performed. Accordingly, the drive device 7A gradually increases the phase current, whereby the power supply current value _Ib becomes _{equal to} or greater than the current threshold value _Ibth , and can shift to PI control.
As described above, the drive device 7A performs the second control when the power supply current value _Ib is less than the current threshold value _Ibth and the phase current target value _Ipth is _{equal to} or greater than the current threshold value _Ibth . Control and PI control can be switched.

  Hereinafter, the flow of control of the duty ratio D in the drive device 7A according to the second embodiment will be described. FIG. 11 is a diagram illustrating a flow of control of the duty ratio D in the driving device 7A according to the second embodiment.

Determination unit 112A acquires the power current _{I b} from the current detection unit 13. Then, the determination unit 112, the power supply current value _{I b} obtained from the current detection unit 13 determines whether a current threshold _{I bth} more (step S201). Determination unit 112A, when the power source current value _{I b} obtained from the current detector 13 is determined to be current threshold _{I bth} more outputs an accurate signal to the estimating unit 113 and PI control unit 115.

When the determination unit 112A outputs an accurate signal, the determination unit 112A increments the detection count N (step 202). Note that the initial value of the detection number N is zero. The determination unit 112A determines whether or not the number of detections N is _{equal to} or greater than a predetermined number threshold Nth (step S203). PI control unit 115, the determination unit 112A, the number of detection times when N is determined to be the predetermined number threshold value _{N th} or more, the phase current estimated value _{I pp} and, subtraction value between the phase current target value _{I pth} The duty ratio D is determined by performing PI control based on the phase current deviation ΔI _p (I _pth −I _pp ) (step S204). Then, the PI control unit 115 outputs the determined duty ratio D to the gate driver circuit 16.
On the other hand, in step S203, the determination unit 112A, when the number of detection times N is determined to be less than the predetermined number threshold value _{N th,} the process proceeds to step S201.

Determination unit 112A, when the power source current value _{I b} obtained from the current detector 13 is determined to be less than the current threshold _{I bth} clears the detection number N to zero (step S205).
Next, the determination unit 112A determines whether or not the phase current target value I _pth input from the _host ECU 2 is _{equal to} or greater than the current threshold value I _bth (step S206). If the determination unit 112A determines that the phase current target value I _pth input from the _host ECU 2 is _greater than or _equal to the current threshold I _bth , the determination unit 112A performs second control to increase the duty ratio D (step S207).
On the other hand, if the determination unit 112A determines that the phase current target value I _pth input from the _host ECU 2 is less than the current threshold value I _bth , the first control for fixing the duty ratio D to the previous duty ratio D is performed. This is performed (step S208).

As described above, the driving device 7A according to the second embodiment is a driving device for the brushless motor 6 that _performs feedback control so that the phase current of the brushless motor 6 becomes the phase current target value I _pth . When the power supply current value _Ib and the phase current target value _Ipth are not within the detectable range, the driving device 7A performs the first control that controls the duty ratio D to a constant value. On the other hand, when the power supply current value _Ib is not in the detectable range and the phase current target value I _pth is in the detectable range, the driving device 7A increases the duty ratio D every predetermined time. . As a result, the driving device 7A can improve the stability of the current control for the brushless motor 6 even when the power supply current _Ib is outside the detectable range and becomes unstable. Further, when the first control is being performed and the command for increasing the phase current is input from the host ECU 2, the driving device 7A gradually increases the phase current and shifts to the PI control. Can do.

As described above, the driving device 7 _{</ b > A} is switched to any one of the first control, the second control, and the PI control from the three relationships of the power supply current value I _b , the phase current target value I _pth, and the detectable range, thereby making the brushless The stability of the current control for the motor 6 can be improved.

(Third embodiment)
Below, the drive device 7B of the brushless motor 6 which concerns on 3rd Embodiment is demonstrated.
FIG. 12 is a diagram illustrating an example of a schematic configuration of a driving device 7B according to the third embodiment.
As shown in FIG. 12, the drive device 7B includes a control unit 11B, an inverter unit 12, a current detection unit 13, and a gate driver circuit 16.

  FIG. 13 is a diagram illustrating an example of a schematic configuration of a control unit 11B according to the third embodiment. As illustrated in FIG. 13, the control unit 11B according to the third embodiment includes a determination unit 112A, an estimation unit 113, and a feedback control unit 114B.

Determination unit 112A determines whether or not the power source current value I _b obtained from the current detector 13 is in the detectable range. Further, determination unit 112A determines whether or not phase current target value I _pth input from _host ECU 2 is within a detectable range.

Determination unit 112A, when the power supply current value I _b obtained from the current detector 13 has determined to be in the detectable range outputs a correct signal to the estimating unit 113 and a feedback control unit 114B.
If the determination unit 112A determines that the power supply current value _Ib and the phase current target value _Ipth are not within the detectable range, the feedback control unit 114B outputs a first control signal that instructs execution of the first control. Output to.
If the determination unit 112A determines that the power supply current value _Ib is not in the detectable range and the phase current target value _Ipth is in the detectable range, the determination unit 112A instructs to perform the second control. The control signal is output to the feedback control unit 114B.

As shown in FIG. 13, the feedback control unit 114B includes a PI control unit 115B, a first control unit 116, a second control unit 118, and a storage unit 117.
PI control unit 115B, when the power source current value I _b to be fed back is in the detectable range, and the phase current estimated value I _pp of estimator 113 have been calculated, is the subtraction value between the phase current target value I _pth The duty ratio D is determined by performing PI control based on the phase current deviation ΔI _p (I _pth −I _pp ).

The PI control unit 115B has the same configuration as the PI control unit 115. That is, the PI control unit 115B includes a subtractor 211, adders 212 and 215, and multipliers 213 and 214. Here, the feature of the PI control unit 115B is that, when shifting from the second control to the PI control, the initial value of the integral value in the PI control is determined based on the duty ratio of the second control immediately before the shift. is there. For example, when the PI control unit 115B shifts from the first control or the second control to the PI control, the PI control such that the duty ratio D immediately before the shift coincides with the duty ratio when the PI control is started. Determine the initial value of the integral at. Here, as described above, the initial value of the integral value is the initial value of the integral value that the adder 212 adds to the phase current deviation ΔI _p at the start of PI control. Further, the duty ratio D immediately before the transition is the duty ratio D of the first control immediately before the transition or the duty ratio D of the second control immediately before the transition.

For example, the PI control unit 115B calculates an initial value of the integral value for PI control using the following formula.
Initial value of integral value = {duty ratio D before transition− (phase current target value I _{pth −phase} current estimated value I _pp ) × proportional control gain Kp} / integral control gain Ki (1)

Here, when the PI control unit 115B shifts from the first control or the second control to the PI control, the initial value of the integral value in the PI control is determined based on the duty ratio of the second control immediately before the shift. The effect of this will be described with reference to the drawings.
For example, when shifting from the first control or the second control to the PI control, the duty ratio D calculated by the PI control may not match the duty ratio D before the shift. Accordingly, as shown in FIG. 14, the first control or the second control in the transition time of T ₁ of the time a transition to PI control, it may change the duty ratio D is generated. Therefore, immediately after the transition time of T _1, the variation of the phase current and supply current I _b becomes larger. In this case, the transition between the first control or the second control and the PI control may be repeated.

FIG. 15 is a time chart of current feedback control in the drive device 7B according to the third embodiment. When the drive device 7B according to the third embodiment shifts from the first control or the second control to the PI control, the initial value of the integral value in the PI control is set so that the duty ratios before and after the shift match. decide. Thus, driver 7B from the first control or the second control in the transition time of T ₁ of the time a transition to PI control, it is possible to suppress the variation of the duty ratio D is generated, the phase current and supply the variation of the current value I _b becomes possible inhibition.

  The flow of controlling the duty ratio D in the drive device 7B according to the third embodiment will be described below. FIG. 16 is a diagram illustrating a flow of control of the duty ratio D in the drive device 7B according to the third embodiment.

Determination unit 112A acquires the power current _{I b} from the current detection unit 13. Then, the determination unit 112, the power supply current value _{I b} obtained from the current detection unit 13 determines whether a current threshold _{I bth} more (step S301). Determination unit 112A, when the power source current value _{I b} obtained from the current detector 13 is determined to be current threshold _{I bth} more outputs an accurate signal to the estimating unit 113 and PI control unit 115.

When the determination unit 112A outputs an accurate signal, the determination unit 112A increments the detection count N (step 202). Note that the initial value of the detection number N is zero. The determination unit 112A determines whether or not the number of detections N is _{equal to} or greater than a predetermined number threshold Nth (step S303).
PI control unit 115B, when the detected number of times N is determined to be the predetermined number threshold value N _th or more, the initial value of the integral value in the PI control is determined based on the duty ratio D immediately before the transition. For example, the PI control unit 115B calculates an initial value of the integral value for PI control using the equation (1) (step S304). Then, the PI control unit 115B uses a value obtained by adding the phase current deviation ΔI _p (I _pth −I _pp ) with respect to the calculated initial value of the integrated value as a new integrated value for PI calculation in PI control. The duty ratio D is determined (step S305).

On the other hand, in step S303, the determination unit 112A, when the number of detection times N is determined to be less than the predetermined number threshold value _{N th,} the process proceeds to step S301.

Determination unit 112A, when the power source current value _{I b} obtained from the current detector 13 is determined to be less than the current threshold _{I bth} clears the detection number N to zero (step S306).
Next, the determination unit 112A determines whether or not the phase current target value I _pth input from the _host ECU 2 is greater than or _equal to the current threshold value I _bth (step S307). When the determination unit 112A determines that the phase current target value I _pth input from the _host ECU 2 is _{equal to} or greater than the current threshold value I _bth , the determination unit 112A performs second control to increase the duty ratio D (step S308).
On the other hand, if the determination unit 112A determines that the phase current target value I _pth input from the _host ECU 2 is less than the current threshold value I _bth , the first control for fixing the duty ratio D to the previous duty ratio D is performed. This is performed (step S309).

As described above, the drive device 7B according to the third embodiment is a drive device for the brushless motor 6 that _performs feedback control so that the phase current of the brushless motor 6 becomes the phase current target value I _pth . When the driving device 7B shifts from the first control or the second control to the PI control, the driving device 7B determines the initial value of the integral value in the PI control based on the duty ratio immediately before the shift. Thereby, the driving device 7B can improve the stability of the current control for the brushless motor 6 even when the power source current _Ib is outside the detectable range and becomes unstable.

The drive unit 7B, in case of transition to PI control from the first control or the second control, it is possible to suppress the variation of the duty ratio D is generated, the variation of the phase current and supply current value I _b It becomes possible to suppress.

  In this embodiment, the sensorless brushless motor 6 can be driven without using the rotation sensor 10. In this case, for example, by detecting the magnetic pole position of the rotor based on the induced voltage appearing at the motor terminal, the drive control of the brushless motor 6 can be performed without a position sensor without providing a rotation sensor (position sensor). it can.

  You may make it implement | achieve the control parts 11, 11A, and 11B in embodiment mentioned above with a computer. In that case, a program for realizing this function may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be read into a computer system and executed. Here, the “computer system” includes an OS and hardware such as peripheral devices. The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory inside a computer system serving as a server or a client in that case may be included and a program held for a certain period of time. Further, the program may be a program for realizing a part of the above-described functions, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system. You may implement | achieve using programmable logic devices, such as FPGA (Field Programmable Gate Array).

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes designs and the like that do not depart from the gist of the present invention.

  The execution order of each process such as operation, procedure, step, and stage in the apparatus, system, program, and method shown in the claims, the description, and the drawings is particularly “before” or “prior to”. It should be noted that the output can be realized in any order unless the output of the previous process is used in the subsequent process. Regarding the operation flow in the claims, the specification, and the drawings, even if it is described using “first”, “next”, etc. for the sake of convenience, it means that it is essential to carry out in this order. It is not a thing.

DESCRIPTION OF SYMBOLS 1 Electric oil pump 5 Oil pump 6 Brushless motor 7 Drive apparatus 10 Rotation sensor 11 Control part 12 Inverter part 13 Current detection part 16 Gate driver circuit 112 Determination part 113 Estimation part 114 Feedback control part 115 PI control part 116 1st control part 117 Storage unit 118 Second control unit

Claims (8)

The brushless motor driving apparatus that performs feedback control so that the phase current of the brushless motor becomes a phase current target value that is a target value of the phase current,
A current detection unit that detects a power supply current value that is a current value of a power supply current supplied from the power supply device;
An inverter unit having a switching element and converting the power supply current into the phase current by PWM control of on and off of the switching element;
A control unit for controlling a duty ratio of the PWM control according to a power supply current value fed back from the current detection unit;
Have
The controller is configured to control the duty ratio to a constant value when the power supply current value fed back is not within a predetermined detectable range.   The brushless motor driving apparatus according to claim 1, wherein the detectable range is a range of a current value that can be accurately detected by the current detection unit. The controller is
An estimation unit that calculates a phase current estimated value that is an estimated value of the phase current according to the power supply current value fed back and the duty ratio;
A feedback control unit that feedback-controls the duty ratio so that the phase current estimated value becomes the phase current target value;
Have
The feedback control unit includes:
A first control unit that performs a first control to control the duty ratio to a constant value when the power supply current value and the phase current target value are not within the detectable range;
When the power supply current value is not in the detectable range and the phase current target value is in the detectable range, a second control is performed to increase the duty ratio every predetermined time. A control unit;
The drive apparatus of the brushless motor of Claim 2 characterized by comprising.   When the power supply current value is in the detectable range, the feedback control unit performs PI control so that a difference value between the phase current estimated value and the phase current target value becomes a predetermined value, thereby the duty ratio. The brushless motor driving apparatus according to claim 3, further comprising a PI control unit that controls the motor.   When the PI control unit shifts from the first control or the second control to the PI control, the PI control unit determines an initial value of an integral value in the PI control based on a duty ratio immediately before the shift. The brushless motor driving device according to claim 4, wherein the driving device is a brushless motor. 6. The brushless motor driving apparatus according to claim 5, wherein an initial value of an integral value for the PI control is calculated by the following equation.
Initial value of integral value = {duty ratio before transition-(phase current target value-phase current estimated value) x proportional control gain} / integral control gain   The brushless motor drive device according to any one of claims 1 to 6, wherein the brushless motor is a drive source of an electric oil pump. A method of driving the brushless motor, wherein feedback control is performed so that a phase current of the brushless motor becomes a phase current target value that is a target value of the phase current,
A current detection step of detecting a power supply current value that is a current value of a power supply current supplied from the power supply device;
An output step of having a switching element, converting the power source current into the phase current by PWM control of on and off of the switching element, and outputting the phase current to the brushless motor;
A control step for controlling a duty ratio of the PWM control according to a power supply current value fed back from the current detection step;
Have
The method for driving a brushless motor, wherein the control step controls the duty ratio to a constant value when the power supply current value fed back is not within a predetermined detectable range.

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