JP6493067B2 - Motor control device - Google Patents

Description

  The present invention relates to a motor control device.

  There are various types of control for generating a voltage to be applied to the winding of a synchronous motor such as a brushless DC motor (hereinafter referred to as “motor”), and there are cases where they are properly used depending on the purpose.

  In Patent Document 1, when the phase of the motor winding current is advanced, rectangular wave control for generating a rectangular wave voltage is performed, and when it is not necessary to advance the phase of the motor winding. An AC motor drive control device that performs PWM (Pulse Width Modulation) control for generating a voltage having a sine wave waveform is disclosed.

Japanese Patent No. 3683135

  However, if the control method for generating the voltage is different, the generated voltage and current are not the same. In the invention described in Patent Document 1, since the drive system for generating voltage is changed while the motor is rotating, a difference occurs in the generated voltage and current when the drive system is changed. As a result, the rotational speed of the motor is changed. However, there was a problem that it may fluctuate unexpectedly.

  The present invention has been made in view of the above, and an object of the present invention is to provide a motor control device that can suppress fluctuations in the rotation speed of the motor when the voltage generation drive system is changed according to the rotation speed.

In order to solve the above-mentioned problem, the motor control device according to claim 1 can be controlled by two different drive systems, and is a drive that applies a voltage generated by the control to the windings of the three-phase motor. A circuit, a current detection unit for detecting a current flowing in the winding of the three-phase motor according to an applied voltage, and the driving method based on a predetermined command signal before starting the three-phase motor. after controlling the driving circuit, based on the predetermined command signal by controlling the drive circuit in the other drive system, controls the drive circuit to generate a voltage at each of two different drive schemes, the When the voltage generated by the other driving method is applied to the winding of the three-phase motor, the current detected by the current detecting unit is changed to the voltage generated by the one driving method. Applied to the wire Said changing said predetermined command signal to match the current detected by the current detection unit, based on the difference between said predetermined command signal and the command signal obtained by said change, the one of the two drive systems calculates a correction value when the drive system is changed to the other drive system, after the start of the three-phase motor, when changing the driving method of the driving circuit, the correction value input command signal And a drive circuit control unit that controls the drive circuit using a command signal corrected by one of the two different drive methods.

  According to this motor control device, the current detected by applying the voltage generated by the other driving method to the winding of the three-phase motor is changed to the voltage generated by one driving method being the winding of the three-phase motor. The command signal is changed so as to coincide with the current detected by being applied to. When the voltage generation drive system is changed by calculating a correction value based on the difference between the command signal before and after the change and correcting the command signal with the calculated correction value, the fluctuation of the rotation speed of the motor Can be suppressed.

The motor control device according to claim 2 is the motor control device according to claim 1, wherein the drive circuit control unit, before the start of the three-phase motor, the drive circuit controlled by the one drive system After the first phase winding is energized to the ground region via the second phase winding, the drive circuit is controlled by the other driving method to control the second phase from the first phase winding. The correction value is calculated without rotating the rotor of the three-phase motor by energizing the grounding region through the winding.

  According to this motor control device, by preventing the rotor of the three-phase motor from rotating, the fluctuation of the current detected by the current detection unit is suppressed, so that the correction value can be easily calculated.

According to a third aspect of the present invention , in the motor control device according to the first or second aspect, the drive circuit control unit calculates the correction value prior to the first start of the three-phase motor. When the three-phase motor is started after the first time, the command signal is corrected based on the stored correction value.

  According to this motor control device, by using the stored correction value, it is not necessary to calculate a correction value every time the three-phase motor is started, so that the control of the three-phase motor can be simplified and speeded up.

According to a fourth aspect of the present invention , in the motor control device according to the first or second aspect, the drive circuit control unit calculates and stores the correction value every time the three-phase motor is started a predetermined number of times. Then, the command signal is corrected based on the stored correction value.

  According to this motor control device, the three-phase motor can be controlled using the correction value corresponding to the temporal change of the three-phase motor by recalculating the correction value at every predetermined start.

The motor control device according to claim 5, in the motor control apparatus according to any one of claims 1-4, wherein the two drive schemes, the winding of any one phase in accordance with the rotational position of the rotor Is turned off and one of the other two-phase windings is energized from one winding to the other, and the driving circuit is controlled according to the rotational position of the rotor. Energizing the windings of the phases to de-energize, and after the current from one winding of the other two-phase windings to the other winding, the current flowing from the one winding to the other winding is attenuated And a second driving method for controlling the driving circuit so as to be performed.

  According to this motor control device, in the second drive method, energization is performed to attenuate the current remaining in the energized winding. Such energization can reduce noise generated in the induced voltage of the non-energized phase, and facilitates detection of the rotor position based on the induced voltage during low-speed rotation.

The motor control device according to claim 6 is the motor control device according to claim 5 , wherein the drive circuit control unit uses the first drive method when the rotation speed of the three-phase motor is high. When the rotational speed of the three-phase motor is low, each of the drive circuits is controlled by the second drive method.

  According to this motor control device, when the rotational speed of the three-phase motor is low, the second drive method that allows easy detection of the rotor position is used, and when the rotational speed of the three-phase motor is high, the drive circuit is switched. By using the first driving method with less operation, the control of the three-phase motor can be optimized according to the rotational speed.

It is the schematic which shows an example of the motor control apparatus which concerns on embodiment of this invention. It is the schematic which showed an example of the PWM duty command (command signal), the signal applied to the gate of inverter FET, the U-phase voltage, and the V-phase voltage in the motor control apparatus which concerns on embodiment of this invention, (A) Indicates the case of one-side PWM drive, and (B) indicates the case of balanced drive. It is the schematic which showed the operation | movement of the inverter circuit in the electricity supply to the V phase coil from the U phase coil of a motor, (A) shows the case of one-side PWM drive, (B) has shown the case of balanced PWM drive, respectively. It is the flowchart which showed an example of the sensorless control of the starting of the motor in the motor control apparatus which concerns on embodiment of this invention. It is a flowchart of the sensorless drive which concerns on this Embodiment. It is the flowchart which showed an example of the positioning control which concerns on this Embodiment. Timing describing each change in rotor rotational speed, motor current, command duty PWM duty, U-phase terminal voltage, V-phase terminal voltage, and average voltage between U and V phases in the positioning control in the embodiment of the present invention It is an example of a chart.

  FIG. 1 is a schematic diagram illustrating an example of a motor control device 100 according to the present embodiment. In the inverter circuit 114, the ignition switch 124 is turned on, the electric power supplied from the in-vehicle battery 120 is switched, and a voltage to be applied to the stator winding (coil) of the motor 118 that is a three-phase motor is generated. For example, the inverters FET 114A and 44D perform switching to generate a voltage to be applied to a U-phase coil, the inverters FET 114B and 44E to a V-phase coil, and the inverters FET 114C and 44F to a W-phase coil.

  The drains of the inverters FETs 114A, 114B, and 114C are connected to the positive electrode of the on-vehicle battery 120. The sources of the inverters FET 114D, 114E, and 114F are connected to the negative electrode of the battery 120.

  In the present embodiment, the rotational speed and position (rotational position) of the rotor are detected by an induced voltage generated by the rotation of the rotor of the motor 118. The induced voltage is a sinusoidal analog signal that changes according to the rotation of the rotor. In the present embodiment, the induced voltage is converted into a rectangular wave pulse signal by the position detection circuit 116 including a comparator and input to the microcomputer 110. .

  The microcomputer 110 calculates the position of the rotor from the signal input from the position detection circuit 116, and based on the calculated position of the rotor and the signal input from the ECU 122, which is a higher-level control device, the switching of the inverter circuit 114 is performed. The duty ratio of PWM control related to the control is calculated.

  The duty ratio signal calculated by the microcomputer 110 is output to the inverter circuit 114 via the pre-driver 112, and the inverter circuit 114 generates a voltage based on the duty ratio and applies it to the coil of the motor 118.

  A shunt resistor 126 having a resistance value of about 0.2 mΩ to several Ω is provided between the inverter circuit 114 and the negative electrode of the battery 120, and a current detection circuit 128 is connected to both ends of the shunt resistor 126. The current detection circuit 128 amplifies the potential difference between both ends of the shunt resistor 126 and outputs a voltage value proportional to the current of the shunt resistor 126 as a signal. The signal output from the current detection circuit 128 is input to the microcomputer 110, and the microcomputer 110 calculates the current of the inverter circuit 114 as a motor current based on the signal output from the current detection circuit 128.

  As will be described later, in this embodiment, the correction value is calculated based on the change in the motor current when the PWM control method is changed. When changing the PWM control method while the motor is rotating, the duty ratio is corrected by the calculated correction value, thereby suppressing fluctuations in the rotation speed of the motor due to the PWM control method change.

  FIG. 2 shows an example of a PWM duty command (command signal), signals applied to the gates of the inverters FETs 114A, 114B, 114D, and 114E, a U-phase voltage 154U, and a V-phase voltage 154V in the motor control device 100 according to the present embodiment. (A) shows a case of one-side PWM drive, and (B) shows a case of balanced drive. The PWM period T in FIG. 2 is a period necessary for PWM control for energizing the ground region from one coil to another, and in FIG. 2, the ground region from the U-phase coil to the ground region via the V-phase coil. This is a period required for PWM control for energizing one pulse. In the present embodiment, the PWM cycle T is approximately 50 μsec.

As shown in the “U-phase upper FET gate waveform” in FIG. 2A, a high level signal is continuously applied to the gate of the inverter FET 114A related to the energization of the U-phase coil, and the inverter FET 114A has a PWM cycle. Continuously on at T. Further, as shown in "V-phase lower FET gate waveform" in FIG. 2 (A), the high level signal having a period T ₁ in accordance with a command signal is applied to the gate of the inverter FET114E according to energization of the V-phase coil Thus, the inverter FET 114E is turned on. As a result, U-phase coil 18U and the V-phase coil 18V is energized, the period _{T 1,} the U-phase voltage 154U is a U-phase coil becomes _V b, V-phase voltage 154V is 0 is the voltage of the positive electrode of the battery 120 A potential difference is generated between the V-phase coil.

  As shown in FIG. 2A, the inverter FET that performs switching for energizing the U-phase coil 18U is continuously turned on, while the inverter FET that performs switching for energizing the V-phase coil 18V is performed. In the present embodiment, the case shown in FIG. 2A is referred to as one-side PWM drive because the PWM control is used to turn on and off.

  As shown in FIG. 2A, due to the influence of the switching operation of the inverter FET 114E, the waveform of the V-phase voltage 154V exhibits a substantially trapezoidal shape instead of a complete rectangular wave.

In the period T ₂ after the elapse of the period T ₁ , the inverter FET 114E is turned off, so that the U-phase voltage 154U indicates the positive voltage V _b of the battery 120, and the V-phase voltage 154V indicates a voltage equal to or higher than V _b . Indicate V-phase voltage 154V is _{V b} voltage higher than in the period _{T 2} are, because the current flows through the parasitic diode of the inverter FET114B is turned off. If the forward voltage is _{V F} of the parasitic diode, V-phase voltage 154V in period _{T 2} are showing the forward voltage _{V F} voltage higher than _{V b.}

Since the U-V line voltage in the PWM period T of the one-side PWM drive is a difference between the U-phase voltage 154U and the V-phase voltage 154V, it is calculated by the following equation (1).
U−V line voltage = (V _b × T ₁ / T) + (− V _F × T ₂ / T) (1)

In the one-way PWM driving, high other than those illustrated in FIG. 2 (A), in the period _{T 2,} the inverter FET114B, after providing the dead time to simultaneously turn off the 114E, the "V-phase upper FET gate waveform" In some cases, the inverter FET 114B is turned on at a level. In the period T ₂ are in such a case the influence of the forward voltage V _F is primarily Oyobi during dead time inverter FET114B is turned off after the period T _1, as a result, U-V line voltage has the formula (1) Slightly larger than the case.

As shown in the “U-phase upper FET gate waveform” in FIG. 2B, in the balanced drive, the inverter FET 114A related to energization to the U-phase coil is turned on after the dead time 152 has elapsed after the rising edge of the command signal. become. At the same time, as shown in “V-phase lower stage FET gate waveform” in FIG. 2B, a high level signal is applied to the gate of the inverter FET 114E related to energization to the V-phase coil, and the inverter FET 114E is turned on. As a result, in the cycle T ″ ₁ , the U-phase voltage 156U is V _b , which is the positive voltage of the battery 120, and the V-phase voltage 156V is 0, causing a potential difference between the U-phase coil and the V-phase coil. The time 152 is a time provided to prevent the inverter FETs connected in series from being turned on at the same time.

Thereafter, as shown in “U-phase upper FET gate waveform” and “V-phase lower FET gate waveform” in FIG. 2B, when the edge of the command signal falls, inverter FET 114A and inverter FET 114E are simultaneously turned off. Then, after the dead time 152 has elapsed, as shown in “U-phase lower FET gate waveform” and “V-phase upper FET gate waveform” in FIG. 2B, a high level signal is applied to the gates of the inverter FET 114B and the inverter FET 114D. Is applied, and the inverter FET 114B and the inverter FET 114D are turned on. As a result, in the cycle T ″ ₂ , the currents of the U-phase coil 18U and the V-phase coil 18V generated by energization of the cycle T ″ ₁ are attenuated.

In the case of FIG. 2B, the current supplied in the cycle T ″ ₁ is attenuated in the cycle T ″ ₂ , thereby balancing the potentials of the inverter circuit 114 and the motor 118 coil. In this embodiment, the case shown in FIG. 2B is referred to as balanced drive.

In the case of FIG. 2 (B), the U-V line voltage in the PWM cycle T of balanced PWM drive is the difference between the U-phase voltage 156U and the V-phase voltage 156V, and is calculated by the following equation (2). The
U-V line voltage _{= {V b × (T "} 1 -T" 2 -2T d / T)} + (- V F × 2T d / T) ... (2)

  3A and 3B are schematic diagrams showing the operation of the inverter circuit 114 when the motor 118 is energized from the U-phase coil 18U to the V-phase coil 18V. FIG. 3A is a one-side PWM drive, and FIG. 3B is a balanced PWM drive. Each case is shown.

  The one-side PWM drive shown in FIG. 3A is a case where the duty ratio of the voltage applied to the motor 118 is increased. In FIG. 3A, the power supplied from the battery 120 is applied to the U-phase coil 18U with the inverter FET 114A turned on, and grounded via the V-phase coil 18V and the inverter FET 114E.

  The lower table of FIG. 3 (A) is, in order from the top, the switching concept of the inverter FET 114A and the inverter FET 114D for switching to energize the U-phase coil 18U, the inverter FET 114B for switching to energize the V-phase coil 18V, and The switching concept of inverter FET114E and the change of the voltage of W phase coil 18W are shown.

  The switching concept of the inverter FET 114A and the inverter FET 114D that performs switching for energizing the U-phase coil 18U in the table of FIG. 3A indicates that the inverter FET 114A is continuously turned on. In addition, the switching concept of the inverter FET 114B and the inverter FET 114E that performs switching for energizing the V-phase coil 18V indicates that the inverter FET 114E is intermittently turned on and off by PWM control.

  In FIG. 3A, a current 140 is a current when the inverter FET 114E is turned on. The current 140 flows to the U-phase coil 18U via the inverter FET 114A that is continuously turned on, and further flows to the ground region via the V-phase coil 18V and the inverter FET 114E.

  In FIG. 3A, a current 142 is a current when the inverter FET 114E is turned off. The current 142 is due to the effect of the current 140 flowing. Even if the inverter FET 114E is turned off, the current 140 flows in the same direction as the current 140, that is, from the U-phase coil 18U to the V-phase coil 18V. This is due to an electromotive force that tries to pass a current through.

  Since the inverter FET 114E is turned off, the current 142 does not flow to the ground region, but only circulates in a circuit constituted by the U-phase coil 18U, the V-phase coil 18V, the parasitic diode of the inverter FET 114B, and the inverter FET 114A. However, as will be described later, the induced voltage generated in the W-phase coil 18W may be affected by the currents 140 and 142.

  In the case of FIG. 3A, since the power of the battery 120 is not energized in the W-phase coil 18W, the waveform at the bottom of the table in FIG. 3A is due to the induced voltage generated in the W-phase coil 18W. is there.

  As described above, the motor 118 according to the present embodiment detects the induced voltage generated in the coil of the phase where the power of the battery 120 is not energized without using the Hall element, and detects the position of the rotor. However, the voltage of the W-phase coil 18W in the lowermost stage in the table of FIG. 3A generates pulse-like noise due to the influence of the currents 140 and 142, etc., and the timing at which a signal optimal for rotor position detection can be extracted. May be limited.

  If the timing at which an optimal signal for rotor position detection can be extracted is limited, the rotor position detection is more difficult as the rotation speed of the motor 118 is lower. This is because as the rotational speed of the motor 118 decreases, the timing at which a non-energized coil such as the W-phase coil 18W shown in FIG. Therefore, when the rotation speed of the motor 118 is low, the PWM control by the balanced PWM drive shown in FIG.

  The balanced PWM drive shown in FIG. 3B is a case where the duty ratio of the voltage applied to the motor 118 is reduced. The lower table in FIG. 3B is, in order from the top, the switching concept of the inverter FET 114A and inverter FET 114D for switching to energize the U-phase coil 18U, the inverter FET 114B for switching to energize the V-phase coil 18V, and The switching concept of inverter FET114E and the change of the voltage of W phase coil 18W are shown.

  The switching concept of the inverter FET 114A and the inverter FET 114D that performs switching for energizing the U-phase coil 18U in the table of FIG. 3B indicates that the inverter FET 114A and the inverter FET 114D are alternately turned on and off. Further, in the switching concept of the inverter FET 114B and the inverter FET 114E that perform switching for energizing the V-phase coil 18V, the inverter FET 114E is turned on when the inverter FET 114A is turned on, and the inverter FET 114B is turned on when the inverter FET 114D is turned on. It is shown that.

  In FIG. 3B, a current 144 is a current when the inverter FET 114A and the inverter FET 114E are turned on. The current 144 flows to the U-phase coil 18U via the inverter FET 114A, and further flows to the ground region via the V-phase coil 18V and the inverter FET 114E.

  In FIG. 3B, a current 146 is a current when the inverter FET 114B and the inverter FET 114D are turned on. Current 146 is a forward current with current 144 in U-phase coil 18U and V-phase coil 18V. In the control for turning on the inverter FET 114B and the inverter FET 114D, a current in the direction opposite to that of the current 144 is passed. However, even when the inverter FET 114B and the inverter FET 114D are turned on due to the influence of the current 144, A current 144 and a forward current are actually observed. However, when the inverter FET 114B and the inverter FET 114D are turned on, there is an effect of attenuating the current 146 due to the influence of the current 144. As a result, the induced voltage generated in the W-phase coil 18W is notable although some spike waves are generated. As a result, it is easy to extract a signal optimal for detecting the position of the rotor 16.

The period T ″ ₂ for turning on the inverter FET 114B and the inverter FET 114D in order to attenuate the current 146 due to the influence of the current 144 may be shorter than the period T ″ ₁ for turning on the inverter FET 114A and the inverter FET 114E. ₂ "period T for _one" period T is different depending on the specifications of the motor 118, specifically determined through experiments or the like using a real machine.

In general, if the duty ratio of the command signal is the same, T ₁ <T ″ ₁ and the forward voltage V _F is about 0.65 V in the silicon-based semiconductor, and the above formulas (1) and (2 ), The U-V line voltage is higher in the one-side PWM drive, and the load of the inverter circuit 114 is reduced in the one-side PWM drive because the number of operations of the switching element is reduced.

  However, as described above, in one-side PWM drive, it is not easy to extract a signal that is optimal for rotor position detection during low-speed rotation. Therefore, it is desirable to perform one-side PWM driving when the motor 118 rotates at high speed and perform balanced PWM driving when the motor 118 rotates at low speed.

  In the present embodiment, the motor 118 is applied to the motor 118 by balanced PWM driving when the rotational speed of the motor 118 is equal to or lower than the predetermined rotational speed, and by one-side PWM driving when the rotational speed of the motor 118 exceeds the predetermined rotational speed. Generate voltage. Alternatively, when the duty ratio of the command signal exceeds a predetermined value, or when the motor current detected by the current detection circuit 128 exceeds a predetermined value, a voltage to be applied to the motor 118 is generated by one-side PWM driving. Also good.

  FIG. 4 is a flowchart showing an example of sensorless control for starting the motor 118 in the motor control apparatus 100 according to the present embodiment. The sensorless control means control for detecting the position of the rotor by detecting the induced voltage generated in the non-conduction phase without using the Hall element as in the motor 118 according to the present embodiment.

  In step 500 of FIG. 4, positioning control is performed before the motor 118 is started. Details of the positioning control will be described later with reference to FIGS. 6 and 7. In the positioning control, the correction value of the command signal for suppressing the fluctuation of the rotation speed of the motor 118 when switching from the balanced PWM driving to the one-side PWM driving. Is calculated.

  In step 502, it is determined whether a specified time has elapsed since the positioning control. If the determination is affirmative, forced commutation control is performed in step 504. In step 504, the coils of the respective phases are sequentially energized at a constant low speed, and the rotor of the motor 118 is rotated while gradually increasing the voltage.

  In step 506, it is determined whether or not the sensorless driving condition is satisfied. Specifically, an affirmative determination is made when the rotational speed of the rotor is improved and the rotor position can be detected by the induced voltage. If the determination in step 506 is affirmative, sensorless driving based on rotor position detection based on the induced voltage is executed in step 508.

  FIG. 5 is a flowchart of sensorless driving in step 508 of FIG. In step 600, it is determined whether or not the driving condition A is satisfied. Specifically, when the rotational speed of the motor 118 exceeds a predetermined rotational speed, the duty ratio of the command signal exceeds a predetermined value, and the motor current detected by the current detection circuit 128 has a predetermined value. It is determined that the drive A condition is satisfied in at least one of the cases where the voltage exceeds the limit, and in step 602, a voltage to be applied to the motor 118 is generated by one-side PWM drive (hereinafter referred to as “drive A”), and the process ends. To do.

  If the determination in step 600 is negative, a voltage to be applied to the motor 118 is generated in step 604 by balanced PWM drive (hereinafter referred to as “drive B”), and the process is terminated.

  FIG. 6 is a flowchart showing an example of the positioning control in step 500 of FIG. In step 700, a command signal having a predetermined duty ratio is applied only between specific two-phase coils, such as a U-phase coil to a V-phase coil, among the U-phase, V-phase, and W-phase coils. Based on this, the voltage generated by drive A is applied. The reason for energizing only between the specific two-phase coils is to prevent the rotor of the motor 118 from rotating. In the present embodiment, when the voltage generated in each of the driving A and the driving B is applied from the specific one-phase coil to the other-phase coil so as not to rotate the rotor, each is detected by the current detection circuit 128. A correction value for the command signal is calculated based on the motor current. Since the fluctuation of the motor current is suppressed by not rotating the rotor, the detection of the motor current and the calculation of the correction value based on the detected motor current are facilitated. As will be described later, in the present embodiment, the current is supplied from the U phase to the V phase, but may be supplied from the V phase to the W phase and from the W phase to the U phase. Also, if the rotor can be rotated because it is possible to detect the average value of the motor current, it is not important to energize the specific one-phase coil to the other one-phase coil as described above. May be.

In step 702, the current generated as a result of energization in step 700 is detected. The current detected in step 702 is, for example, the motor current 162 detected between times t ₀ and t ₁ in FIG. Here, FIG. 7 shows the rotor rotational speed 160, motor current 162, command signal PWM duty 164, U-phase terminal voltage 166U, V-phase terminal voltage 166V, and average between U-V phases in the positioning control in the present embodiment. 3 is an example of a timing chart showing changes in each of voltages 168.

As a trigger that the command signal is input to the initial value (START_DUTY) at time t ₀ in FIG. 7, a voltage generated by the drive A via a V-phase coil 18V from the U-phase coil 18U is energized to ground area. Specifically, the inverter FET 114A is kept on, and the inverter FET 114E is turned on / off according to the initial value of the command signal. The initial value (START_DUTY) is a command signal having a predetermined duty ratio, and corresponds to, for example, a command signal when the drive method is changed from drive B to drive A in the actual control of the motor 118. .

Immediately after such energization, as indicated by the rotational speed 160 in FIG. 7, the rotor may slightly move, and the motor current also varies due to the minute movement. In the present embodiment, the detection of the motor current is continued until time t _{1 in} order to avoid fluctuations in the motor current.

In step 704, it is determined whether the specified time has elapsed. Specified time, for example, according to whether or not the time t ₁ in FIG. 7 has elapsed. If the determination in step 704 is affirmative, the procedure proceeds to step 706. If the determination in step 704 is negative, the procedure returns to step 700, and the energization of the coil by drive A and the detection of the motor current are continued.

In step 706, the voltage generated by the drive B based on the initial command signal (START_DUTY) is applied to the coil. In step 708, the current generated as a result of energization in step 706 is detected. When the duty ratio is based on the same command signal, the voltage generated in the balanced PWM drive (drive B) is lower than that in the one-side PWM drive (drive A). Also in FIG. 7, the average voltage 168 between the U and V phases decreases at time t ₁ when the driving B starts, and the motor current 162 also decreases at time t ₁ .

In step 710, it is determined whether the specified time has elapsed. Specified time, for example, according to whether or not the time has elapsed t ₂ in FIG. If the determination in step 710 is affirmative, the procedure proceeds to step 712. If the determination in step 710 is negative, the procedure returns to step 706 to continue energization of the coil by drive B and detection of the motor current 162.

  In step 712, it is determined whether or not there is a difference between the motor current of drive A and the motor current of drive B. If the determination is affirmative, the motor current of drive A and the motor current of drive B are determined in step 714. The duty ratio of the command signal is adjusted so as to match. In step 716, the motor current of drive B is detected. In step 712, it is determined again whether there is a difference between the motor current of drive A and the motor current of drive B.

Processing during the time _{t 2} time _{t 3} in FIG. 7 corresponds to the processing of step 712 to 716 in FIG. 6. As shown in FIG. 7, extracted Yuki raise the PWM DUTY164 is gradually command signal from the time t _2, the duty ratio when the motor current 162 matches the motor current 162 by driving A up to the time t ₁ as END_DUTY To do.

  If the determination in step 712 is negative, that is, if the motor current of drive A and the motor current of drive B match, the correction value of the command signal is calculated based on END_DUTY, and the process ends. The correction value of the command signal is based on a difference between END_DUTY and START_DUTY, but may be a difference between END_DUTY and START_DUTY or a ratio between END_DUTY and START_DUTY. When the difference between END_DUTY and START_DUTY is used as the correction value, when the voltage applied to the coil of the motor 118 is generated by the drive B, the correction value is added to the duty ratio of the command signal and corrected based on the duty ratio. A voltage is generated by the drive B. When the ratio of END_DUTY and START_DUTY is used as the correction value, when the voltage applied to the coil of the motor 118 is generated by the drive B, the duty ratio of the command signal is multiplied by the correction value to correct the duty ratio. A voltage is generated by the drive B.

  In the present embodiment, the motor current 162 of the drive B is driven by correcting the duty ratio of the command signal of the drive B that is the balanced PWM drive in which the motor current 162 is lower than the drive A that is the one-side PWM drive. It is made to correspond to the motor current 162 of A.

  Contrary to the above-described embodiment, by correcting the duty ratio of the command signal of the drive A that is the one-side PWM drive in which the motor current 162 is larger than the drive B that is the balanced PWM drive, The motor current 162 may be matched with the motor current 162 of the drive B. In such a case, when the voltage to be applied to the coil of the motor 118 is generated by the drive A, the drive is performed based on the duty ratio corrected by subtracting the correction value that is the difference between END_DUTY and START_DUTY from the duty ratio of the command signal. A generates a voltage. Or, when the voltage applied to the coil of the motor 118 is generated by the drive A, the voltage at the drive A is based on the duty ratio corrected by dividing the duty ratio of the command signal by the correction value that is the ratio of END_DUTY and START_DUTY. Is generated.

  Or, contrary to the case of FIG. 7, after applying the voltage generated by the drive B, the voltage generated by the drive A is applied, and the correction value for correcting the duty ratio of the command signal of the drive A is calculated. Good.

  In the present embodiment, the above-described correction value is calculated when the motor 118 is started. However, the correction value is calculated and stored in the storage device when the motor 118 is started for the first time, and thereafter, the command signal is calculated using the stored correction value. The duty ratio may be corrected. Alternatively, the correction value is recalculated every predetermined number of times of starting the motor 118, the recalculated correction value is stored in the storage device, and the duty of the command signal is calculated using the recalculated correction value at the predetermined number of start times. The ratio may be corrected.

  As described above, according to this embodiment, when motor 118 is started, the value of each motor current 162 when a voltage generated by two different driving methods is applied to a specific two-phase coil of motor, respectively. The correction value of the duty ratio of the command signal when switching the driving method is calculated. By correcting the duty ratio of the command signal of one drive method with such a correction value, fluctuations in the rotation speed of the motor can be suppressed when the voltage generation drive system is changed according to the rotation speed.

18U ... U phase coil, 18V ... V phase coil, 18W ... W phase coil, 100 ... motor control device, 110 ... microcomputer, 112 ... predriver, 114 ... inverter circuit, 114A, 114B, 114C, 114D, 114E, 114F ... Inverter FET, 116 ... Position detection circuit, 118 ... Motor, 120 ... Battery, 124 ... Ignition switch, 126 ... Shunt resistance, 128 ... Current detection circuit, 140, 142, 144, 146 ... Current, 152 ... Dead time, 154U ... U phase voltage, 154V ... V phase voltage, 156U ... U phase voltage, 156V ... V phase voltage, 160 ... rotational speed, 162 ... motor current, 164 ... PWM DUTY, 166U ... U phase terminal voltage, 166V ... V phase terminal voltage 168: Average voltage between U and V phases, T: PWM cycle

Claims (6)

A drive circuit that can be controlled by two different drive systems and applies a voltage generated by the control to the windings of the three-phase motor;
A current detection unit for detecting a current flowing in the winding of the three-phase motor according to the applied voltage;
Before starting the three-phase motor, after controlling the drive circuit with one drive system based on a predetermined command signal, control the drive circuit with the other drive system based on the predetermined command signal, The current detection unit controls the drive circuit to generate a voltage in each of two different drive systems, and the voltage generated in the other drive system is applied to the winding of the three-phase motor. The predetermined command signal is changed so that the detected current coincides with the current detected by the current detection unit by applying the voltage generated by the one driving method to the winding of the three-phase motor. is allowed, with on the basis of the difference between said predetermined command signal and the command signal obtained by said alteration, it calculates a correction value for changing from the one driving system of the two drive systems to the other drive system, Of the three-phase motor When the driving method of the driving circuit is changed after operation, the input command signal is corrected based on the correction value, and the driving signal is corrected using the command signal corrected by one of the two different driving methods. A drive circuit controller for controlling the circuit;
Including a motor control device. The drive circuit control unit controls the drive circuit by the one drive method before starting the three-phase motor, and energizes the ground region from the first phase winding through the second phase winding. Then, the rotor of the three-phase motor is rotated by controlling the drive circuit with the other drive method and energizing the ground region through the second-phase winding from the first-phase winding. the motor control device according to claim 1 for calculating the correction value without causing. The drive circuit controller calculates and stores the correction value prior to the first start of the three-phase motor, and the command signal based on the stored correction value at the start of the three-phase motor after the first time. The motor control apparatus of Claim 1 or 2 which correct | amends. Said drive circuit control unit, the calculated and stored correction value for each start-up of a predetermined number of the three-phase motor, according to claim 1 or 2 for correcting the command signal based on the correction value the storage Motor control device. The two drive systems are configured so that one of the windings is de-energized according to the rotational position of the rotor, and one of the other two-phase windings is energized to the other winding. Depending on the first drive system that controls the drive circuit and the rotational position of the rotor, either one of the windings is de-energized, and one of the other two-phase windings is energized to the other. and then, any one of claims 1 to 4, and a second driving system for controlling the drive circuit so that energization is to attenuate the current flowing from the one winding to the other winding the motor control device according to. The drive circuit control unit uses the first drive method when the rotation speed of the three-phase motor is high, and uses the second drive method when the rotation speed of the three-phase motor is low. The motor control device according to claim 5, wherein each of the motors is controlled.

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