JP2010110042A - Motor controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor controller which can execute determination about the demagnetization of a motor where the possibility of wrong determination is reduced. <P>SOLUTION: The motor controller includes a resolver 32 which detects the rotational speed of a rotor, and a control unit 30 which controls the rotation of the motor. The control unit 30 determines whether the operation state of the motor belongs to a determination execution range or belongs to a determination inhibition range, based on the detected rotational speed MRN1 of the rotor and a torque command TR1, and in case that the operation range belongs to the determination execution range, it executes demagnetization determination for determining whether the demagnetizing factor of the permanent magnet of the motor has dropped under a specified value, based on the motor voltage. The control unit 30 inhibits the determination of demagnetization in case that the operation state of the motor belongs to the determination inhibition range. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a motor control device, and more particularly to a motor control device that controls a motor including a permanent magnet and performs a demagnetization determination of the permanent magnet.

Japanese Patent Laid-Open No. 8-103093 (Patent Document 1) calculates the demagnetization factor by detecting the magnetic flux of the magnet by calculation or actual measurement in order to suppress the torque drop caused by the demagnetization of the magnet in the salient pole type permanent magnet motor. Then, a technique for calculating a phase control target based on the demagnetization factor and controlling the motor current to the calculated phase is disclosed.
JP-A-8-103093

  In order to determine whether or not the motor can normally generate torque, a motor demagnetization determination is performed.

  However, if the motor demagnetization determination is performed even when no current is flowing, the dead time cannot be accurately interpolated, resulting in a loss of accuracy and erroneous determination. Therefore, in such a state where no current flows, it is preferable not to perform the demagnetization determination that decreases accuracy.

  An object of the present invention is to provide a motor control device capable of executing motor demagnetization determination with reduced possibility of erroneous determination.

  In summary, the present invention is a motor control device, and includes a sensor that detects the rotational speed of the rotor and a control unit that controls the rotation of the motor. The control unit determines whether the operation state of the motor belongs to the determination execution region or the determination prohibition region based on the detected rotation speed of the rotor and the torque command value, and when the operation state belongs to the determination execution region Performs a demagnetization determination that determines whether the demagnetization factor of the permanent magnet of the motor is lower than a predetermined value based on the motor voltage, and if the operating state belongs to the determination prohibition region, Judgment is prohibited.

  Preferably, the determination prohibition region is a region where the current flowing through the motor is smaller than a predetermined value.

  Preferably, a control part performs control of the inverter which drives a motor. The inverter includes first and second switching elements that form an upper arm and a lower arm, respectively. The control unit performs a switching control by providing a dead time for avoiding that the first and second switching elements are simultaneously turned on, and corrects the motor voltage according to the dead time.

  Preferably, the control unit notifies the driver when the demagnetization factor is larger than a predetermined value as a result of the demagnetization determination.

  According to the present invention, when a demagnetization determination is performed, a warning or the like due to an erroneous determination is avoided.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and description thereof will not be repeated.

  FIG. 1 is a circuit diagram showing a configuration of a vehicle 100 according to an embodiment of the present invention. The vehicle 100 may be any of an electric vehicle that drives wheels with a motor, a fuel cell vehicle, and a hybrid vehicle that uses a motor and an engine in combination for driving the vehicle.

  Referring to FIG. 1, vehicle 100 includes a battery B, a voltage sensor 10, system main relays SR1 and SR2, a capacitor C1, an inverter 14, a temperature sensor 35, a current sensor 24, and a control device 30. Is provided.

  The battery B is a secondary battery such as nickel metal hydride or lithium ion. Voltage sensor 10 detects DC voltage value VB output from battery B, and outputs the detected DC voltage value VB to control device 30. System main relays SR1, SR2 are turned on / off by a signal SE from control device 30. More specifically, system main relays SR1 and SR2 are turned on by signal SE of H (logic high) level and turned off by signal SE of L (logic low) level. Capacitor C1 smoothes the voltage across terminals of battery B when system main relays SR1 and SR2 are on.

  Vehicle 100 further includes a voltage sensor 21, a current sensor 11, a boost converter 12, a capacitor C <b> 2, a voltage sensor 13, and a resolver 32.

The resolver 32 detects the rotational speed MRN1 and transmits it to the control device 30.
Current sensor 11 detects a direct current flowing between battery B and boost converter 12 and outputs the detected current to control device 30 as a direct current value IB.

  Boost converter 12 has a first end connected to reactor L1 connected to the positive electrode of battery B via system main relay SR1, and IGBT elements Q1, Q2 connected in series between the output terminals of boost converter 12 that outputs voltage VH. And diodes D1, D2 connected in parallel to IGBT elements Q1, Q2, respectively.

  Reactor L1 has the other end connected to the emitter of IGBT element Q1 and the collector of IGBT element Q2. The cathode of diode D1 is connected to the collector of IGBT element Q1, and the anode of diode D1 is connected to the emitter of IGBT element Q1. The cathode of diode D2 is connected to the collector of IGBT element Q2, and the anode of diode D2 is connected to the emitter of IGBT element Q2.

  Voltage sensor 21 detects the voltage on the input side of boost converter 12 as voltage value VL. Current sensor 11 detects the current flowing through reactor L1 as current value IB. Capacitor C2 is connected to the output side of boost converter 12 and accumulates energy sent from boost converter 12, and smoothes the voltage. Voltage sensor 13 detects the voltage on the output side of boost converter 12, that is, the voltage between electrodes of capacitor C2, as voltage value VH.

  Inverter 14 receives the boosted voltage from boost converter 12 and drives motor generator M1. Further, inverter 14 returns the electric power generated in motor generator M <b> 1 due to regenerative braking to boost converter 12. At this time, boost converter 12 is controlled by control device 30 to operate as a step-down circuit.

  Motor generator M1 is a motor for generating torque for driving drive wheels (not shown) of vehicle 100. This motor may be incorporated in a hybrid vehicle, for example, having a function of a generator driven by an engine and operating as an electric motor for the engine so that the engine can be started.

  Inverter 14 includes a U-phase arm 15, a V-phase arm 16, and a W-phase arm 17. U-phase arm 15, V-phase arm 16, and W-phase arm 17 are connected in parallel between the output lines of boost converter 12.

  U-phase arm 15 includes IGBT elements Q3 and Q4 connected in series, and diodes D3 and D4 connected in parallel with IGBT elements Q3 and Q4, respectively. The cathode of diode D3 is connected to the collector of IGBT element Q3, and the anode of diode D3 is connected to the emitter of IGBT element Q3. The cathode of diode D4 is connected to the collector of IGBT element Q4, and the anode of diode D4 is connected to the emitter of IGBT element Q4.

  V-phase arm 16 includes IGBT elements Q5 and Q6 connected in series, and diodes D5 and D6 connected in parallel with IGBT elements Q5 and Q6, respectively. The cathode of diode D5 is connected to the collector of IGBT element Q5, and the anode of diode D5 is connected to the emitter of IGBT element Q5. The cathode of diode D6 is connected to the collector of IGBT element Q6, and the anode of diode D6 is connected to the emitter of IGBT element Q6.

  W-phase arm 17 includes IGBT elements Q7 and Q8 connected in series, and diodes D7 and D8 connected in parallel with IGBT elements Q7 and Q8, respectively. The cathode of diode D7 is connected to the collector of IGBT element Q7, and the anode of diode D7 is connected to the emitter of IGBT element Q7. The cathode of diode D8 is connected to the collector of IGBT element Q8, and the anode of diode D8 is connected to the emitter of IGBT element Q8.

  An intermediate point of each phase arm is connected to each phase end of each phase coil of motor generator M1. That is, the motor generator M1 is a three-phase permanent magnet motor, and one end of each of the three coils of the U, V, and W phases is connected to the middle point. The other end of the U-phase coil is connected to the connection node of IGBT elements Q3 and Q4. The other end of the V-phase coil is connected to a connection node of IGBT elements Q5 and Q6. The other end of the W-phase coil is connected to a connection node of IGBT elements Q7 and Q8.

  Current sensor 24 detects the current flowing through motor generator M1 as motor current value MCRT1, and outputs motor current value MCRT1 to control device 30.

  Control device 30 receives torque command value TR1, rotation speed MRN1, voltage values VB, VL, VH, current value IB, and motor current value MCRT1. Control device 30 then outputs a boost instruction PWU and a step-down instruction PWD to boost converter 12. Furthermore, control device 30 provides inverter 14 with a drive instruction PWMI1 for converting a DC voltage, which is an output of boost converter 12, into an AC voltage for driving motor generator M1, and an AC voltage generated by motor generator M1. A regenerative instruction PWMC1 which is converted into a DC voltage and returned to the boost converter 12 side is output.

  Next, the operation of boost converter 12 will be briefly described. Boost converter 12 operates as a boost circuit serving as a forward conversion circuit that supplies power from battery B to inverter 14 during powering operation. Conversely, during regenerative operation, boost converter 12 also operates as a step-down circuit as a reverse conversion circuit that regenerates power generated by motor generator M1 in battery B.

  Boost converter 12 operates as a booster circuit by turning on and off IGBT element Q2 with IGBT element Q1 turned off. That is, when IGBT element Q2 is on, a path is formed in which a current flows from the positive electrode of battery B to the negative electrode of battery B via reactor L1 and IGBT element Q2. While this current is flowing, energy is accumulated in the reactor L1.

  When IGBT element Q2 is turned off, the energy stored in reactor L1 flows to inverter 14 side through diode D1. As a result, the voltage between the electrodes of the capacitor C2 increases. Therefore, the output voltage of boost converter 12 applied to inverter 14 is boosted.

  On the other hand, boost converter 12 operates as a step-down circuit by turning on and off IGBT element Q1 with IGBT element Q2 turned off. That is, when the IGBT element Q1 is on, the current regenerated from the inverter 14 flows to the IGBT element Q1, the reactor, and the battery B.

  In the state where IGBT element Q1 is off, a loop including reactor L1, battery B, and diode D2 is formed, and the energy stored in reactor L1 is regenerated in battery B. In this reverse conversion, the time during which the battery B receives power is longer than the time during which the inverter 14 supplies power, and the voltage at the inverter 14 is stepped down and regenerated by the battery B. The operation of boost converter 12 is performed by appropriately controlling the above power running operation and regenerative operation.

  In order to further reduce the loss, synchronous control may be performed in which the IGBT elements Q1 and Q2 are made conductive in synchronization with the timing when forward current flows in the diodes D1 and D2, respectively, in the above operation.

  The regenerative control includes braking accompanied by regenerative power generation when a foot brake operation is performed by a driver driving a hybrid vehicle or an electric vehicle. Moreover, even when the foot brake is not operated, it includes a case where the vehicle is decelerated or accelerated while regenerative power generation is performed by turning off the accelerator pedal during traveling.

  FIG. 2 is a flowchart showing the control for the motor demagnetization determination executed by the control device 30 of FIG. The process of this flowchart is called and executed every time a predetermined time elapses from a predetermined main routine or every time a predetermined condition is satisfied.

  Referring to FIGS. 1 and 2, when the process is started, motor torque and rotational speed are acquired in step S1. The motor torque is a torque command value TR1, and the rotation speed is a rotation speed MRN1 obtained from the resolver 32 in FIG.

  Subsequently, in step S2, it is determined whether or not the motor operating point defined by the torque and the rotational speed falls within the determination area.

FIG. 3 is a diagram showing the determination execution region used in step S2 of FIG.
Referring to FIG. 3, the vertical axis represents the torque command value, and the horizontal axis represents the rotational speed. A region where the torque command value is 0 or close thereto is set as a determination prohibition region where the motor demagnetization determination is not performed. When the torque command value is 0, the current flowing through the motor is also 0 or close thereto. This is because when the current flowing through the motor is 0, as will be described later, the accuracy of dead time correction cannot be obtained, and therefore correct determination may not be performed.

  The judgment prohibition area may be judged by the absolute value of the torque command value being below a threshold value close to zero, or the motor current is detected and the absolute value is below a threshold value close to zero. You may judge by.

  In step S2, if the motor operating point defined by the torque command value and the motor rotational speed is within the determination region, the process proceeds to step S2. On the other hand, if the motor operating point is not within the determination area, the process proceeds to step S4.

  In step S3, motor demagnetization determination is executed. Hereinafter, the motor demagnetization determination will be described.

[Principle of demagnetization calculation]
The amount of magnetic flux of the rotor can be seen by a counter electromotive voltage generated in proportion to the rotational speed. The counter electromotive voltage cannot be directly measured by the control device 30 at any rotation, but can be calculated from the q-axis voltage control value, and from this value, it is detected that the amount of magnetic flux of the rotor is decreasing. .

The q-axis voltage equation is shown below for normal and demagnetization.
Vq_map = ωφ + ωLdId: When normal (1)
Vq_dgus = K · ωφ + ωLdId: at the time of demagnetization (2)
FIG. 4 is a vector diagram at normal time.

FIG. 5 is a vector diagram at the time of demagnetization.
Since the q-axis voltage is uniquely determined by using the rotation speed, Id, and Iq as arguments, if the q-axis voltage at the normal time is given as a map (Vq_map) in advance, the magnetic flux can be calculated by equations (1) and (2). Decrease amount appears as a difference between the control voltage Vq_dgus and the map voltage Vq_map. Since ωφ can be calculated from the rotation speed and the counter-electromotive constant, the current demagnetization factor (1-K) can be calculated on the control device 30 by the following equation.

(1-K) = (Vq_map−Vq) / ωφ (3)
FIG. 6 is a diagram showing a voltage map in which the voltage Vq_map used in Expression (3) is stored.

  The q-axis voltage map (Vq_map) is obtained using the current vector (id, iq) and the rotational speed ω as arguments. Therefore, two Vqs corresponding to id and iq taken in a lattice point are prepared as shown in FIG. 6 on the low rotation side / high rotation side, and the rotation speed direction is linearly interpolated to implement the voltage Vq_map. Get the value. Separate maps on the power running side / regeneration side.

  Referring to FIG. 2 again, after the demagnetization rate (1-K) based on the equation (3) is calculated in step S3, the demagnetization determination is executed. The demagnetization determination can be made based on, for example, whether or not the demagnetization factor 1-K is larger than a predetermined threshold value. As the demagnetization occurs, the motor causes a torque drop, and the motor may not be able to output the torque as commanded.

  Therefore, the process proceeds to step S5, and the control device 30 outputs the result of the demagnetization determination. For example, the driver is informed of demagnetization with a warning lamp or the like, or when a display device is installed, a warning is displayed on the display to urge the driver to repair. Further, the diagnostic result may be stored in a nonvolatile memory so that it can be referred to at the time of periodic inspection.

  On the other hand, if the motor operating point is not in the determination region in step S2, that is, if the operating point is in the determination prohibition region in FIG. 3, the process proceeds to step S4. In step S4, motor demagnetization determination is prohibited. In the determination prohibition region, the torque is small and the current is close to zero. It will be explained a little more that an error is likely to occur in the determination result in such a state.

When the demagnetizing factor is obtained by equation (3), dead time correction is performed based on the following equation (4). Note that “√3” indicates the square root of 3.
Vq_dt = VH × (dead time (μs) / one carrier period (μs)) × √3 (dq axis conversion coefficient) × cos θ (4)
FIG. 7 is a vector diagram showing a difference in voltage with and without dead time correction.

  Even in the no-current state, the current I is sampled and the dead time correction is performed, but cannot be corrected correctly due to the current ripple.

  The current phase θ in FIG. 7 is not stable due to current ripple. For this reason, an error may occur in the dead time correction. Equation (4) can be applied in a large current state where the current is stable. Whether or not the state is a large current state may be determined based on whether or not the absolute value of the current value exceeds a threshold value appropriately obtained through experiments or the like.

FIG. 8 is a waveform diagram showing the relationship between the current value and the dead time correction voltage in a large current state.
FIG. 9 is a diagram showing the relationship among the determination value, dead time correction value, and map voltage value in a large current state.

  As shown in FIG. 8, if the current is large, the dead time correction voltage is stable. Therefore, the determination value is accurately obtained based on the relationship shown in FIG.

  FIG. 10 is a waveform diagram showing the relationship between the current value in the no-current state and the dead time correction voltage.

  FIG. 11 is a diagram illustrating a relationship among a determination value, a dead time correction value, and a map voltage value in a no-current state.

  As shown in FIG. 10, in the no-current state, the detected current value is a minute current ripple. This current ripple component causes an unstable dead time correction value. As shown in FIG. 11, the determination value becomes unstable due to the unstable dead time correction value.

Therefore, in order to avoid such an unstable determination being executed, the motor demagnetization determination prohibition is executed in step S4 in FIG.
As a result, a warning or the like is not erroneously notified based on an inaccurate determination result.

  When the process of step S4 or S5 is completed, the process proceeds to step S6, and control is transferred to the main routine.

  Finally, this embodiment will be summarized with reference to FIG. 1 again. The motor control device of the present embodiment includes a resolver 32 that detects the rotational speed of the rotor and a control device 30 that controls the rotation of the motor. The motor generator M1 has, for example, a built-in permanent magnet in the rotor and a current that generates a rotating magnetic field in the stator coil. Based on the detected rotor rotational speed MRN1 and torque command value TR1, control device 30 determines whether the motor operating state belongs to the determination execution region or the determination prohibition region, and the operation state enters the determination execution region. When belonging, a demagnetization determination is performed based on the motor voltage to determine whether or not the demagnetization rate of the permanent magnet of the motor is lower than a predetermined value. The control device 30 prohibits the demagnetization determination when the motor operating state belongs to the determination prohibition region of FIG.

  Preferably, the determination prohibition area shown in FIG. 3 is an area where the current flowing through the motor becomes smaller than a predetermined value.

  Preferably, control device 30 executes control of inverter 14 that drives motor generator M1. Inverter 14 includes first and second switching elements that form an upper arm and a lower arm, respectively. The upper arm and the lower arm are provided in each of the U, V, and W phases. For example, the U-phase arm 15 is provided with an IGBT element Q3 corresponding to the upper arm and an IGBT element Q4 corresponding to the lower arm. For example, the V-phase arm 16 is provided with an IGBT element Q5 corresponding to the upper arm and an IGBT element Q6 corresponding to the lower arm. For example, the W-phase arm 17 is provided with an IGBT element Q7 corresponding to the upper arm and an IGBT element Q8 corresponding to the lower arm. The control device 30 performs a switching control by providing a dead time for preventing the first and second switching elements from being turned on simultaneously, and corrects the motor voltage according to the dead time as shown in FIG. That is, the voltage Vq_map obtained from the map is corrected with the dead time correction value, and a determination value for determining demagnetization is calculated.

  Preferably, the control device 30 notifies the driver when the demagnetization factor is larger than a predetermined value as a result of the demagnetization determination.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is a circuit diagram showing a configuration of a vehicle 100 according to an embodiment of the present invention. 2 is a flowchart showing control for motor demagnetization determination executed by a control device 30 of FIG. 1. It is the figure which showed the determination execution area | region used by step S2 of FIG. It is a vector diagram at the time of normal. It is a vector diagram at the time of demagnetization. It is a figure which shows the voltage map which memorize | stored voltage Vq_map. It is a vector diagram showing a difference in voltage with and without dead time correction. It is the wave form diagram which showed the relationship between the electric current value in a large current state, and a dead time correction voltage. It is the figure which showed the relationship between the judgment value in a heavy current state, a dead time correction value, and the voltage value of a map. FIG. 6 is a waveform diagram showing a relationship between a current value in a no-current state and a dead time correction voltage. It is the figure which showed the relationship between the determination value in a no-current state, a dead time correction value, and the voltage value of a map.

Explanation of symbols

  10, 13, 21 Voltage sensor, 11, 24 Current sensor, 12 Boost converter, 14 Inverter, 15 U phase arm, 16 V phase arm, 17 W phase arm, 30 Control device, 32 Resolver, 35 Temperature sensor, B battery, C1, C2 capacitor, D1-D8 diode, L1 reactor, M1 motor generator, Q1-Q8 IGBT element, SR1, SR2 System main relay.

Claims (4)

A sensor for detecting the rotational speed of the rotor;
A control unit for controlling the rotation of the motor,
The control unit determines whether the motor operating state belongs to the determination execution region or the determination prohibition region based on the detected rotation speed of the rotor and the torque command value, and the operation state enters the determination execution region. If it belongs, a demagnetization determination is performed based on the motor voltage to determine whether the demagnetization factor of the permanent magnet of the motor is lower than a predetermined value, and the operation state belongs to the determination prohibition region And a motor control device that prohibits the demagnetization determination.   The motor control device according to claim 1, wherein the determination prohibition region is a region where a current flowing through the motor is smaller than a predetermined value. The control unit executes control of an inverter that drives the motor,
The inverter includes first and second switching elements that form an upper arm and a lower arm, respectively.
The control unit performs a switching control by providing a dead time for preventing the first and second switching elements from being turned on simultaneously, and corrects the motor voltage according to the dead time. 2. The motor control device according to 2.   The motor control device according to any one of claims 1 to 3, wherein the controller notifies the driver when the demagnetization factor is larger than the predetermined value as a result of the demagnetization determination.

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