WO2018146793A1

WO2018146793A1 - Inverter control device and vehicle driving system

Info

Publication number: WO2018146793A1
Application number: PCT/JP2017/004923
Authority: WO
Inventors: 敦明横山
Original assignee: 日産自動車株式会社
Priority date: 2017-02-10
Filing date: 2017-02-10
Publication date: 2018-08-16
Also published as: JP6822493B2; JPWO2018146793A1

Abstract

Provided is a control device for an inverter that drives a motor including a magnet, the control device including: a rotation sensor that detects the rotation state of the motor; a current sensor that detects the current in the motor; and a controller that controls the inverter, wherein the controller calculates a voltage instruction value for controlling the motor voltage on the basis of a torque instruction value, a detection value representing the rotation state detected by the rotation sensor, and a detected current detected by the current sensor, calculates a demagnetization determination threshold in accordance with the rotation state, compares a torque-voltage instruction value included in the voltage instruction value with the demagnetization determination threshold, and determines whether or not demagnetization of the magnet has occurred in accordance with the result of the comparison.

Description

Inverter control device and vehicle drive system

The present invention relates to an inverter control device and a vehicle drive system.

It is determined whether or not the voltage command value Vq has decreased below a predetermined threshold value. If the voltage command value Vq has decreased, the behavior of Vq is further monitored, and if Vq is steady, the motor is identified as being demagnetized. A control device is known (Patent Document 1).

JP 2011-259253 A

However, there is a problem that demagnetization cannot be accurately determined when the operating point of operation changes.

The problem to be solved by the present invention is to provide an inverter control device and a vehicle drive system that can determine demagnetization even when the operating point of driving varies.

The present invention calculates a demagnetization determination threshold according to the rotation state of the motor, compares the torque voltage command value with the demagnetization determination threshold, and determines whether or not demagnetization of the magnet has occurred according to the comparison result. The above-mentioned problem is solved by determining.

According to the present invention, there is an effect that demagnetization can be determined even when the operating point of driving varies.

FIG. 1 is a block diagram of a vehicle drive system according to the present embodiment. FIG. 2 is a block diagram of the drive system according to the present embodiment. FIG. 3 is a block diagram of the inverter control apparatus according to the present embodiment. FIG. 4 is a flowchart showing a control flow of demagnetization determination by the controller shown in FIG. FIG. 5 is a flowchart showing a control flow of a controller of an inverter control device according to another embodiment of the present invention. FIG. 6 is a block diagram of a vehicle drive system according to another embodiment of the present invention. FIG. 7 is a block diagram of a vehicle drive system according to another embodiment of the present invention. FIG. 8 is a block diagram of a vehicle drive system according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<< First Embodiment >>
FIG. 1 is a block diagram showing a vehicle drive system including an inverter control device according to an embodiment of the present invention. Hereinafter, the inverter control device of the present example will be described with reference to an example in which the inverter control device is provided to an electric vehicle. The inverter control device of the present example is a hybrid including at least a motor, such as a parallel type hybrid vehicle and a series type hybrid vehicle. It can also be applied to vehicles.

As shown in FIG. 1, the vehicle control system including the inverter control device of the present example includes a battery 1, an inverter 2, a motor 3, a speed reducer 4, drive wheels 5, and a controller 100. The vehicle drive system is not limited to the configuration shown in FIG. 1 and may include other configurations such as auxiliary devices.

The battery 1 is a vehicle power source and is a battery group in which a plurality of secondary batteries are connected in series or in parallel. A lithium ion battery etc. are used for a secondary battery. The inverter 2 includes a plurality of switching elements such as IGBTs, and converts AC power output from the battery 1 into DC power by switching on and off the switching elements according to a switching signal from the controller 100. Further, the inverter 2 converts AC power generated by the regenerative operation of the motor 3 into DC power, and outputs the DC power to the battery 1. A current sensor is connected between the inverter 2 and the motor 3. The current sensor detects the current flowing through the motor 3 and outputs the detected value to the controller 100.

The motor 3 is connected to the drive shaft of the vehicle and is a vehicle drive source that is driven by AC power from the inverter 2. The motor 3 is an electric motor such as a permanent magnet synchronous motor. Further, a rotation angle sensor is connected to the motor 3, and a detection value of the rotation angle sensor is output to the controller 100. The output shaft of the motor 3 is connected to the left and right drive wheels 5 via the speed reducer 4 and the left and right drive shafts. The motor 3 regenerates energy by generating a regenerative driving force by the rotation of the drive wheels 5.

The controller 100 determines the vehicle state such as the accelerator opening, the vehicle speed and the gradient, the SOC of the battery 1, the chargeable / dischargeable power of the battery 1, the generated power of the motor 3, etc. A drive torque (necessary torque) for outputting torque in response to a driver's request is commanded to the inverter 2. The driver's request is determined by the accelerator operation and the brake operation.

The controller 100 controls the motor 3 via the inverter 2 while optimizing the efficiency of the drive system of the vehicle according to the driving state of the vehicle and the state of the battery 1. In FIG. 1, one controller 100 is shown as a control part for controlling the vehicle, but the controller 100 may be a plurality of controllers such as a motor controller and an integrated controller. Various controllers are connected by a CAN communication network. The controller 100 includes a memory 110, a CPU 120, and the like.

Next, the vehicle drive system will be described with reference to FIG. FIG. 2 is a block diagram of the drive system.

The inverter 2 includes

upper arm elements

21, 23, and 25 that form an upper arm circuit,

lower arm elements

22, 24, and 26 that form a lower knitting circuit, a smoothing capacitor 27, a discharge resistor 28, and a discharge switch 29. And a drive circuit 30.

The

upper arm elements

21, 23, and 25 have a main configuration of a circuit in which switching elements Q1, Q3, and Q5 as power devices and diodes D1, D3, and D5 are connected in parallel. The collector terminal of the switching element Q1 and the cathode terminal of the diode D1 are connected, and the collector terminal of the switching element Q1 and the anode terminal of the diode D1 are connected. Similarly, the

lower arm elements

22, 24, and 26 are mainly configured by a circuit in which switching elements Q2, Q4, and Q6 as power devices and diodes D2, D4, and D6 are connected in parallel. The connection between switching element Q2 to switching element Q6 and diodes D2 to D6 is the same as the connection between switching element Q1 and diode D1.

In the present embodiment, three pairs of circuits in which two switching elements Q1 to Q6 are connected in series are electrically connected to the battery 1 by being connected between the power supply line P and the power supply line N. Each connection point for connecting the switching elements is electrically connected to the three-phase output portion of the three-phase motor 3. The power line P is connected to the positive side of the battery 1, and the power line N is connected to the negative side of the battery 1.

The connection point between the emitter terminal of the switching element Q1 and the collector terminal of the switching element Q2 is a U-phase output, and the connection point between the emitter terminal of the switching element Q3 and the collector terminal of the switching element Q4 is a V-phase output. The connection point between the emitter terminal of Q5 and the collector terminal of the switching element Q6 is a W-phase output and is connected to the three-phase wiring of the motor 3. The

upper arm elements

21, 23, 25 and the

lower arm elements

22, 24, 26 constitute a two-level three-phase inverter circuit 20.

The smoothing capacitor 27 is an element that is connected between the inverter circuit 20 and the battery 1 and smoothes the electric power from the battery 1. The smoothing capacitor 27 is connected between the power supply lines P and N.

The discharge resistor 28 and the discharge switch 29 are connected in series, and the series circuit of the discharge resistor 28 and the discharge switch 29 is connected between the power supply lines P and N. The discharge resistor 28 discharges the electric charge charged in the smoothing capacitor 27. The controller 100 controls on / off of the discharge switch 29. When the discharge switch 29 is turned on, the smoothing capacitor 27 and the discharge resistor 28 are brought into conduction, and discharge is performed.

The drive circuit 30 has a function of switching on and off the switching elements S1 to S6 based on a switching signal transmitted from the controller 100. *

The motor 3 is connected to the connection point of the switching elements Q1 and Q2, the connection point of the switching elements Q3 and Q4, and the connection point of the switching elements Q5 and Q6 in each phase of the inverter circuit.

The relay switch 7 is connected between the battery 1 and the smoothing capacitor 27 of the inverter 2.

The controller 100 is a controller for controlling the drive circuit 30. Based on the torque command value input from the outside, the phase current of the motor 3, and the rotation speed (rotation speed) of the motor 3, the controller 100 outputs the required torque of the torque command value from the motor 3. Calculate the current command value. The phase current of the motor 3 is detected by a current sensor 8 connected between the inverter circuit 20 and the motor 3, and the rotational speed of the motor 3 is calculated from the detection value of the resolver 9 provided in the motor 3. The

Then, the controller 100 generates a switching signal for supplying the power required by the motor 3 and outputs it to the drive circuit 30. Then, the drive circuit 30 switches on and off each of the switching elements Q1 to Q6 based on the switching signal. Thereby, the controller 100 is controlling the inverter 2 by PWM control.

Next, a control block related to inverter control in the controller 100 will be described with reference to FIG. FIG. 3 is a block diagram of the inverter 2, the motor 3, and the controller 100. The controller 100 includes a rotation speed controller 31, a current command value calculator 32, a current controller 33, a non-interference controller 34, a two-phase three-phase voltage converter 35, a rotation speed calculator 36, and a three-phase two-phase current converter. 37.

The rotation speed controller 31 matches the rotation speed detection value (ω _G : motor rotation speed) output from the rotation speed calculator 36 with the rotation speed command value (ω _G ^* ) of the motor 3 output from the controller 100. It is a PID controller that calculates the torque command value (T ^* ) of the motor 3 so that The rotational speed controller 31 receives the rotational speed command value (ω _G ^* ) and the rotational speed detection value (ω _G ) as inputs, calculates a torque command value (T ^* ) by the following equation (1), and obtains a current command value. The result is output to the calculator 32.

However, the K _p is a proportional gain, the K _I is an integral gain, the _the K _D derivative gain, the T _D is the time constant of the approximate differentiation, s is a Laplace operator, the omega _G the rotation speed detection value, omega _G ^* indicates the rotational speed command value. The rotational speed command value (ω _G ^* ) is a target value calculated by the controller 100. The controller 100 calculates the target torque according to the user's request according to the vehicle state, and calculates the rotation speed necessary for outputting the target torque as the rotation speed command value.

The current command value calculator 32 inputs the torque command value (T ^* ), the voltage (V _dc ) of the battery 1, and the rotation speed detection value (ω _G ) indicating the angular frequency of the motor 3. The dq axis current command values (I _d ^* , I _q ^* ) are calculated and output to the current controller 33. The dq axis represents the axis of the rotational coordinate system by the magnetic flux axis of the magnet and the axis orthogonal to the magnet axis. The current command value calculator 32 receives the dq-axis current command values (I _d ^* , I _q ^* ) using the torque command value (T ^* ), the rotation speed detection value (ω _G ), and the voltage (V _dc ) as indices. A map for output is stored in the memory 110. The map is an optimum command value that minimizes the loss of the motor 3 and the loss of the inverter 2 with respect to the input of the torque command value (T ^* ), the rotation speed detection value (ω _G ), and the voltage (V _dc ). Is output. Then, the current command value calculator 32 refers to the map and calculates the dq axis current command value (I _d ^* , I _q ^* ).

The current command value calculator 32 includes a dq-axis current based on the detected value of the current sensor 8 in addition to the torque command value (T ^* ), the voltage (V _dc ) of the battery 1 and the rotation speed detection value (ω _G ). (I _d , I _q ) and chargeable / dischargeable power (P _in , P _out ) of the battery 1 are input, and the current command value calculator 32 calculates the dq axis current command value. The dq-axis current command value is a target value of the current of the motor 3, and includes an excitation current command value and a torque current command value.

The current controller 33 receives the dq-axis current command value (I _d ^* , I _q ^* ) and the dq-axis current (I _d , I _q ) as inputs, performs control calculation using the following equation (2), The dq axis voltage command value (v _d ^* , v _q ^* ) is output. The dq-axis voltage command values (v _d ^* , v _q ^* ) are target values of the motor 3 voltage, and include an excitation voltage command value and a torque voltage command value.

Here, K _pd and K _pq indicate proportional gains, and K _id and K _iq indicate integral gains.

The current controller 33 may calculate the dq axis voltage command values (v _d ^* , v _q ^* ) with reference to a map corresponding to the above equation (2).

The non-interference controller 34 calculates dq-axis non-interference voltages (v _ddcpl , v _qdcpl ) for canceling the generated interference voltage when current flows through the d-axis and q-axis of the motor 3. The voltage equation of the motor 3 is generally expressed by the following equation (3) when expressed in dq coordinates.

Where L _d is the d-axis inductance, L _q is the q-axis inductance, _Ra is the winding resistance of the motor 3, ω _re is the electrical angular velocity, φ _a is the magnetic flux density (torque constant), and p is the differential Indicates an operator.

When equation (3) is transformed by Laplace transform for each component, it is expressed by the following equation.

However, each of the current response models Gp is represented by the following equation.

As shown in the equation (3), there is a speed electromotive force that interferes between the dq axes, and in order to cancel this, the non-interference controller 34 has a non-interference voltage (v expressed by the following equation (6). _ddcpl , _vqdcpl ).

A subtractor is provided on the output side of the current controller 33 and the non-interference controller 34. In the subtracter, the non-interference voltage (v _d ^* , v _q ^* ) represented by the equation (6) ( By subtracting v _ddcpl , v _qdcpl ), the interference term in equation (4) is canceled, and the dq-axis current is expressed by the following equation (7).

The two-phase three-phase voltage converter 35 receives the dq axis voltage command values (v _d ^* , v _q ^* ) and the detected value θ of the resolver 9 as input, and uses the following equation (8) to Converts dq-axis voltage command values (v _d ^* , v _q ^* ) to u, v, w-axis voltage command values (v _u ^* , v _v ^* , v _w ^* ) in the fixed coordinate system and outputs them to inverter 2 To do.

The three-phase two-phase current converter 37 is a control unit that performs three-phase to two-phase conversion. The phase current (I _u , I _v , I _w ) and the detected value θ of the magnetic pole position detector 52 are input as fixed coordinates. The phase currents (I _u , I _v , I _w ) of the system are converted into phase currents (I _d , I _q ) of the rotating coordinate system, and the current command value calculator 32, current controller 33, and non-interacting controller 34 are converted. Output to.

The current sensor 8 is provided for each of the U phase and the V phase, detects a phase current (I _u , I _v ), and outputs it to the three-phase two-phase current converter 37. The w-phase current is not detected by the current sensor 8. Instead, the three-phase two-phase current converter 37 calculates the w-phase current based on the input phase currents (I _u , I _v ). .

A resolver (rotation sensor) 9 is a detector that is provided in the motor 3 and detects the position of the magnetic pole of the motor 3, and outputs a detection value (θ) to the rotation speed calculator 36. The resolver 9 detects the rotation state of the motor 3 at a predetermined cycle. The rotation speed calculator 36 calculates a rotation speed detection value (ω _G ) that is an angular frequency of the motor 3 from the detection value (θ) of the resolver 9, and outputs it to the rotation speed controller 31 and the current command value calculator 32. .

Then, when the phase currents (I _d , I _q ) are input to the current controller 33, the control device is controlled by a current control loop with a predetermined gain. The inverter 2 generates a PWM control signal for switching on and off of the switching element based on the input voltage command values (v ^* _u , v ^* _v , v ^* _w ) under the control of the current control loop. Based on the PWM control signal, the switching element is operated to convert electric power.

The determination threshold calculator 41 calculates a determination threshold (v _qd ^* ) for determining demagnetization. The demagnetization determination unit 42 compares the voltage command value (v _q ^* ) with the determination threshold value (v _qd ^* ), and based on the comparison result, whether or not demagnetization of the magnet included in the motor 3 has occurred. Determine. The determination of demagnetization by the determination threshold calculator 41 and the demagnetization determination unit 42 will be described later.

By the way, in the permanent magnet type synchronous motor of the motor 3, for example, a strong magnet such as a neodymium magnet is used. This magnet is magnetized to obtain a magnetic force, but if an excessive magnetic force is applied in the opposite direction, the magnetic force cannot be maintained. This phenomenon is demagnetization. When demagnetization occurs in the motor for driving the vehicle, the torque for driving the vehicle decreases because the magnetic force of the motor is weak despite the current flowing through the motor.

Demagnetization, to influence the voltage command value (v q _^*), it is possible to determine the demagnetization from the change of the voltage command value (v q _^*). As shown in the above equation (3), the torque voltage (v _q ) changes according to the rotation speed of the motor 3, so that the voltage command value (v _q ^* ) also changes depending on the motor rotation speed. The number of rotations of the motor varies depending on the state of the vehicle, the driving operation of the driver, and the like, and is not steady. Therefore, the voltage command value (v _q ^* ) is not a steady value. The decrease in the voltage command value (v _q ^* ) is caused not only by demagnetization but also by a change in the motor rotation speed. In the present embodiment, the following control is performed to determine demagnetization under a state where the operating point of operation varies.

Next, control of the demagnetization determination by the controller 100 will be described with reference to FIG. FIG. 4 is a flowchart showing a control flow of demagnetization determination by the controller 100. Note that the control flow shown in FIG. 4 is repeatedly executed at a predetermined cycle. The control cycle of the control flow may be a sufficiently small cycle (for example, a 1 / 10th cycle with respect to the driving cycle) with respect to the time during which the rotation speed varies (corresponding to the driving cycle of the vehicle).

In step S1, the demagnetization determination unit 42 acquires a voltage command value (v _q ^* ). In step S2, the demagnetization determination unit 42 calculates an average value (v _q ^* _AVE ) of the voltage command value (v _q ^* ). The average value of the voltage command value _{^{_{^{_{(v q *) (v q}}}}} * AVE) , including the voltage command value obtained immediately before the _(v ^{q *),} a plurality of past times (e.g., last 5 times) voltage command component Calculation is performed using the value (v _q ^* ).

In step S3, the demagnetization determination unit 42 calculates the absolute value of the difference between the current voltage command value (v _q ^* ) and the average value (v _q ^* _AVE ), and calculates the absolute value of the difference and a predetermined threshold ( Compare D ₁₎ and. The predetermined threshold value (D ₁ ) is a threshold value indicating the fluctuation range of the voltage command value (v _q ^* ), and is set in advance according to the allowable fluctuation range. Since the fluctuation of the voltage command value (v _q ^* ) corresponds to the fluctuation of the motor rotation speed (ω _G ), the threshold value (D ₁ ) indicates the fluctuation width of the motor rotation speed (ω _G ). . The lower the threshold (D ₁ ), the higher the accuracy of excitation determination.

When the absolute value of the difference is smaller than the threshold value (D ₁ ), the demagnetization determination unit 42 determines that the fluctuation of the motor rotation speed is small, and executes the control in step S4. On the other hand, when the absolute value of the difference is equal to or greater than the threshold value (D ₁ ), the demagnetization determination unit 42 determines that the fluctuation of the motor rotation speed is large, and executes the control of step S11.

In step S4, the demagnetization determination unit 42 increments the counter (A). In step S5, the demagnetization determination unit 42 compares the counter (A) with the threshold value (A _th ). The threshold value (A _th ) represents the time during which the fluctuation range of the voltage command value (v _q ^* ) is less than the threshold value (D ₁ ). The higher the threshold value (A _th ), the longer the time during which the rotational speed is stable. The threshold value (A _th ) is set to 100 times, for example. When the counter (A) is larger than the threshold value (A _th ), the demagnetization determining unit 42 determines that the motor rotation speed stabilization time has continued for a predetermined time or more, and executes the control of step S6. On the other hand, when the counter (A) is equal to or smaller than the threshold value (A _th ), the control flow returns to step S1, and the demagnetization determination unit 42 executes the control of step S1.

In step S6, the determination threshold value calculator 41 calculates a determination threshold value (v _qd ^* ) corresponding to the motor rotation speed (ω _G ). The determination threshold value (v _qd ^* ) is a threshold value for determining demagnetization, and is a value corresponding to the motor rotation speed (ω _G ). The memory 110 stores a map in which the motor rotation speed (ω _G ) is associated with the determination threshold value (v _qd ^* ). That is, when the motor rotation speed (ω _G ) varies, the determination threshold value (v _qd ^* ) indicated by the map also becomes a different value.

When the determination threshold calculator 41 acquires the motor rotation speed (ω _G ), the determination threshold calculator 41 identifies the determination threshold (v _qd ^* ) corresponding to the current motor rotation speed (ω _G ) on the map while referring to the map. .

In step S7, the demagnetization determination unit 42 calculates the difference (v _qd ^* −v _q ^* ) between the determination threshold value (v _qd ^* ) specified on the map and the current voltage command value (v _q ^* ). The calculated difference is compared with a predetermined threshold (D ₂ ). The predetermined threshold value (D ₂ ) indicates a decrease amount of the voltage command value (v _q ^* ) due to demagnetization, and is set in advance accordingly.

When the difference is larger than the threshold value (D ₂ ), the demagnetization determination unit 42 determines that the voltage command value (v _q ^* ) is lower than the normal value, and executes the control of step S8. On the other hand, when the difference is less than the threshold value (D ₂ ), the demagnetization determination unit 42 determines that no demagnetization has occurred and the current voltage command value (v _q ^* ) is normal, The control in step S11 is executed.

In step S8, the demagnetization determination unit 42 increments the counter (B). In step S9, the demagnetization determination unit 42 compares the counter (B) with the threshold value (B _th ). The threshold value (B _th ) indicates the number of determinations determined as abnormal, and is determined according to the determination accuracy of demagnetization. The threshold value (B _th ) is determined in advance, and is set to 3 times, for example.

If the counter (B) is higher than the threshold value (B _th ), in step S10, the demagnetization determination unit 42 determines that demagnetization has occurred. When the controller 100 determines that excitation is generated by the demagnetization determination unit 42, the controller 100 may notify the driver of the occurrence of demagnetization by displaying a lamp or the like. Then, the control flow ends. On the other hand, when the counter (B) is less than the threshold value (B _th ), the control flow ends.

If the absolute value of the difference between the voltage command value (v _q ^* ) and the average value (v _q ^* _AVE ) is greater than or equal to the threshold value (D ₁ ) in step S3, the demagnetization determination device 42 in step S11. Resets the counter (A). If the absolute value of the difference between the current voltage command value (v _q ^* ) and the determination threshold value (v _qd ^* ) is less than the threshold value (D ₂ ) in step S7, the demagnetization determination device is determined in step S11. 42 resets the counter (A). Then, after the counter (A) is reset, the control flow ends. If the absolute value of the difference between the current voltage command value (v _q ^* ) and the determination threshold value (v _qd ^* ) is less than the threshold value (D ₂ ), the demagnetization determination unit 42 determines in step S11. The counter (B) may be reset.

As described above, in the present embodiment, the determination threshold value (v _qd ^* ) corresponding to the rotation state of the motor 3 is calculated, and the torque voltage command value (v _q ^* ) is compared with the determination threshold value (v _qd ^* ). In accordance with the comparison result, it is determined whether or not the magnet 3 of the motor 3 is demagnetized. Thus, demagnetization can be determined under the situation where the torque voltage command value (v _q ^* ) varies like the motor 3.

In the present embodiment, as a mask condition, the control flow from step S1 to step S5 adds that the fluctuation of the motor rotation speed is small. However, depending on the required demagnetization determination accuracy, the step is performed. The control flow from S1 to step S5 may be omitted. That is, in the present embodiment, the determination threshold value (v _qd ^* ) becomes a value corresponding to the fluctuation of the motor rotation speed by the calculation process in step S6. For this reason, when the motor rotation speed fluctuates, the determination threshold value (v _qd ^* ) also fluctuates. Therefore, even when the torque voltage command value (v _q ^* ) fluctuates due to fluctuations in the motor rotation speed, it can be accurately reduced. Can determine magnetism. As a mechanism of magnet demagnetization, a state where the reverse magnetic field exceeds the knick point is a demagnetization state. And when a reverse magnetic field exceeds a nick point, magnetic force will reduce sharply. Therefore, demagnetization can be accurately determined if the determination threshold (v _qd ^* ) can follow fluctuations in the motor rotation speed.

Further, the mask condition is not limited to the fluctuation range of the motor rotation speed, and may include other elements such as a detection current. For example, when the detected current or the motor speed is outside a predetermined range, the voltage command value or the motor speed may be an abnormal value due to an abnormality in the current sensor 8, the resolver 9, or the CPU 120. Therefore, if the detected current or the motor rotation speed is out of the predetermined range and the mask condition is not satisfied, the controller 100 may not execute the excitation determination control.

Further, the determination threshold value calculator 41 may calculate, for example, a moving average value of the torque voltage command value (v _q ^* ) as the determination threshold value (v _qd ^* ) instead of the calculation process using the map. The determination threshold value calculator 41 may calculate the determination threshold value (v _qd ^* ) not only by the moving average but also by an arithmetic process using an arithmetic expression including at least the motor rotation number as a variable.

<< Second Embodiment >>
An inverter control device according to another embodiment of the present invention will be described. In the present embodiment, the calculation control of the determination threshold value (v _qd ^* ) by the controller 100 is different from the first embodiment. Other configurations and control methods are the same as those in the first embodiment described above, and the description thereof is incorporated.

The controller 100 calculates a torque voltage command value (v _q ^* ) based on the motor rotation speed (ω _G ) at a predetermined cycle, and associates the motor rotation speed (ω _G ) with the torque voltage command value (v _q ^* ). Then, it is stored in the memory 110 as a map. The controller 100, the current motor speed (omega _G) to the newly torque voltage command value based (v q _^*) when calculating the current motor speed torque voltage command value corresponding to the (ω _G) (v _q ^* ) is specified on the map. Controller 100, a torque voltage command value specified on the map (v q _^*) and the newly computed torque voltage command value (v q _^*) is compared with the smaller torque voltage command values (v _q ^* ) _Is set as a new determination threshold (v _qd ^* ). The controller 100 associates the newly set determination threshold value (v _qd ^* ) with the motor rotation speed (ω _G ) and stores it in the map.

That is, when the controller 100 newly calculates the torque voltage command value (v _q ^* ), the controller 100 newly stores the torque voltage command value (v _q ^* ) stored as the determination threshold value (v _qd ^* ) on the map, Then, select low with the calculated torque voltage command value (v _q ^* ), set the lower torque voltage command value (v _q ^* ) as the determination threshold value (v _qd ^* ), and update the map.

Next, the control flow of the inverter control device will be described. FIG. 5 is a flowchart showing a control flow of an inverter control apparatus according to another embodiment of the present invention. Since the control flow of steps S1 to S11 is the same as the control flow of steps S1 to S11 according to the first embodiment, a description thereof will be omitted.

If the difference (v _qd ^* −v _q ^* ) between the current voltage command value (v _q ^* ) and the determination threshold (v _qd ^* ) is equal to or less than the threshold (D ₂ ) in step S7, the process proceeds to step S12. Thus, the demagnetization determination unit 42 resets the counter (A). In step S13, the controller 100 specifies the determination threshold value (v _qd ^* ) corresponding to the current motor rotation speed while referring to the map. The controller 100 compares the specified determination threshold value (v _qd ^* ) with the current voltage command value (v _q ^* ). If the current voltage command value (v _q ^* ) is lower than the specified determination threshold value (v _qd ^* ), the controller 100 newly determines the current voltage command value (v _q ^* ) in step S14. Set the threshold (v _qd ^* ) and update the map. On the other hand, when the current voltage command value (v _q ^* ) is equal to or greater than the specified determination threshold value (v _qd ^* ), the controller 100 ends the control flow without updating the map.

As described above, in the present embodiment, the rotation state of the motor 3 detected by the resolver 9 and the calculated torque voltage command value (v _q ^* ) are stored in the memory 110 in association with each other, and the current rotation state is obtained. based torque voltage command value (v q _^*) is newly computed, the newly computed torque voltage command value (v q _^*) with the stored torque voltage command value to the memory 110 (v q _^*) and of The lower value is set as the determination threshold (v _qd ^* ). As a result, the determination threshold value (v _qd ^* ) is updated while managing the decrease in the torque voltage command value (v _q ^* ) due to the individual variation of the inverter 2 or the motor 3, the variation of the temperature characteristics of the inverter 2 or the motor 3, or the like. Therefore, the determination accuracy can be increased.

In the present embodiment, the controller 100 associates the motor rotation speed (ω _G ) with the torque voltage command value (v _q ^* ) and stores it in the memory 110 as a map at the initial stage of the vehicle. When the torque voltage command value (v _q ^* ) corresponding to each motor rotation number (ω _G ) is calculated and the corresponding relationship is stored in the memory 110 within the entire operation range, the controller 100 The torque voltage command value (v _q ^* ) may not be updated by select low. When the reverse magnetic field exceeds the knick point, the magnetic force decreases sharply. Therefore, the determination accuracy can be improved without updating the determination threshold value (v _qd ^* ) by selecting low the torque voltage command value (v _q ^* ).

<< Third Embodiment >>
FIG. 6 is a block diagram showing a vehicle drive system according to another embodiment of the present invention. The present embodiment is different from the first embodiment in that the presence or absence of demagnetization is determined while the clutch is disengaged. Other configurations are the same as those in the first embodiment or the second embodiment described above, and the description thereof is incorporated as appropriate.

As shown in FIG. 6, the vehicle drive system includes a clutch 50 in addition to the battery 1 and the like. The clutch 50 connects and disconnects between the motor 3 and the speed reducer 4. The controller 100 controls the clutch 50. When the clutch is disengaged, the motor 3 is not connected to the drive shaft of the vehicle. At this time, since the operation of the motor 3 does not depend on the driver's vehicle operation, the rotation speed of the motor 3 is stabilized.

The controller 100 disengages the clutch according to the driver's operation or the state of the vehicle. Then, the controller 100 determines whether or not demagnetization of the magnet included in the motor 3 has occurred while the clutch 50 is disengaged. The method for determining demagnetization is the same as in the first embodiment. Thereby, demagnetization can be determined in a state where the rotation speed of the motor 3 is stable without affecting the driving request by the driver. As a result, the demagnetization determination accuracy can be increased.

Note that the vehicle drive system according to the present embodiment is also applicable to a hybrid system as shown in FIG. The hybrid vehicle is a parallel-type automobile that uses a plurality of power sources such as an internal combustion engine and a motor generator for driving the vehicle, and includes a battery 1, an inverter 2, a motor 3, left and right drive wheels 5, an internal combustion engine (hereinafter referred to as an engine). 10, a first clutch 11, a second clutch 12, a propeller shaft 13, a differential gear unit 14, a drive shaft 15, and an automatic transmission 17.

The first clutch 11 is interposed between the output shaft of the engine 10 and the rotation shaft of the motor 3, and connects and disconnects (ON / OFF) the power transmission between the engine 10 and the motor 3. Examples of the first clutch 11 include a wet multi-plate clutch that can continuously control the oil flow rate and hydraulic pressure with a proportional solenoid. In the first clutch 11, the hydraulic pressure of the hydraulic unit is controlled based on a control signal from the controller 100, whereby the clutch plate of the first clutch 11 is engaged (including a slip state) or released. A dry clutch may be adopted as the first clutch 11.

The automatic transmission 17 is a stepped transmission that switches the gear ratio such as 7 forward speeds and 1 reverse speed in stages, and automatically switches the gear ratios according to the vehicle speed, the accelerator opening, and the like.

The second clutch 12 may be obtained by diverting some of the frictional engagement elements among the plurality of frictional engagement elements that are engaged at each gear of the automatic transmission 17. Alternatively, the second clutch 12 may be a dedicated clutch different from the automatic transmission 17.

The output shaft of the automatic transmission 17 is connected to the left and right drive wheels 5 via a propeller shaft 13, a differential gear unit 14, and left and right drive shafts 15. In FIG. 1, reference numeral 5 denotes left and right steering front wheels.

The controller 100 connects the clutch 11 and disconnects the clutch 12 while the vehicle is stopped. The controller 100 rotates the engine 10 with the driving force of the motor 3 and operates the auxiliary machinery by the rotation of the engine 10. At this time, since the motor 3 can be driven in a steady state, the rotation speed of the motor 3 is stabilized. Then, the controller 100 determines whether or not demagnetization of the magnet included in the motor 3 has occurred while the clutch 12 is disengaged. Thereby, the determination accuracy of demagnetization can be improved.

As described above, in the present embodiment, the magnet 12 included in the motor 3 is demagnetized while the rotation of the motor 3 is stabilized by disengaging the clutch 12 under the driving environment that does not affect the driving request by the driver. Determine whether it has occurred. Thereby, the determination accuracy of demagnetization can be improved.

In FIG. 7, a rear-wheel drive hybrid vehicle is illustrated, but a front-wheel drive hybrid vehicle or a four-wheel drive hybrid vehicle may be used. The hybrid system may be a series type.

In addition, when the inverter control apparatus according to the first or second embodiment is applied to a vehicle drive system having a clutch as in this embodiment, excitation can be determined with a small fluctuation in the motor rotation speed. The threshold value (D ₁ ) or the threshold value (D ₁ ) may be made smaller. Thereby, the determination accuracy of demagnetization can be improved.

<< 4th Embodiment >>
FIG. 8 is a block diagram showing a vehicle drive system according to another embodiment of the present invention. In the present embodiment, the inverter control system according to the first embodiment or the second embodiment is applied to a vehicle drive system provided with a continuously variable transmission. The configuration and control of the inverter control system are the same as those in the first embodiment or the second embodiment, and the description thereof is incorporated as appropriate.

As shown in FIG. 8, the vehicle drive system includes a continuously variable transmission (CVT) 70 in addition to the battery 1 and the like. The CVT 70 is connected between the motor 3 and the speed reducer 4. The CVT 70 has two pulleys and a belt. The CVT 70 changes the position of the belt between the two pulleys to change the speed, thereby changing the rotation speed of the axle and suppressing fluctuations in the motor rotation speed.

For example, a scene in which the driver performs a brake operation while the vehicle is running and the vehicle speed gradually decreases will be described. Unlike the present embodiment, when the CVT 70 is not provided and the motor 3 is directly connected to the axle, the motor speed decreases as the vehicle speed decreases. The same applies when the motor 3 is connected to the axle via a stepped transmission. On the other hand, when the motor 3 is coupled to the axle via the CVT 70 as in the present embodiment, the motor 3 is coupled directly to the axle, or the motor 3 is coupled via the stepped transmission. As compared with the case where the motor is connected to the axle, fluctuations in the motor rotation speed are suppressed.

And in a vehicle drive system provided with CVT70, demagnetization can be determined in the state where the fluctuation of motor rotation speed was controlled by applying the inverter control device like the 1st embodiment or the 2nd embodiment. Thereby, the determination accuracy of demagnetization can be improved.

When the inverter control device according to the first or second embodiment is applied to a vehicle drive system having the CVT 70 as in the present embodiment, excitation can be determined with a small fluctuation in the motor rotation speed. The threshold value (D ₁ ) or the threshold value (D ₁ ) may be made smaller. Thereby, the determination accuracy of demagnetization can be improved.

DESCRIPTION OF SYMBOLS 1 ... Battery 2 ... Inverter 3 ... Motor 4 ... Reduction gear 5 ... Drive wheel 7 ... Relay switch 8 ... Current sensor 9 ... Resolver 10 ... Engine 11 ... 1st clutch 12 ... 2nd clutch 13 ... Propeller shaft 14 ... Differential gear unit DESCRIPTION OF SYMBOLS 15 ... Drive shaft 17 ... Automatic transmission 20 ...

Inverter circuit

21, 23, 25 ...

Upper arm element

22, 24, 26 ... Lower arm element 27 ... Smoothing capacitor 28 ... Discharge resistor 29 ... Discharge switch 30 ... Drive circuit 31 ... Number-of-rotations controller 32 ... Current command value calculator 33 ... Current controller 34 ... Non-interference controller 35 ... Two-phase / three-phase voltage converter 36 ... Number-of-rotations calculator 37 ... Three-phase / two-phase current converter 41 ... Determination threshold Operation unit 42 ... Demagnetization determination unit 50 ... Clutch 52 ... Magnetic pole position detector 70 ... Continuously variable transmission 100 ... Controller 110 ... Memory 120 ... CP

Claims

In an inverter control device for driving a motor including a magnet,
A rotation sensor for detecting a rotation state of the motor;
A current sensor for detecting the current of the motor;
A controller for controlling the inverter,
The controller is
Based on the torque command value, the detection value of the rotation state detected by the rotation sensor, and the detection current detected by the current sensor, a voltage command value for controlling the voltage of the motor is calculated,
Calculate a demagnetization determination threshold according to the rotation state,
An inverter control device that compares a torque voltage command value included in the voltage command value with the demagnetization determination threshold value and determines whether or not demagnetization of the magnet has occurred according to a comparison result.
The inverter control device according to claim 1,
The controller is
The rotation state detected by the rotation sensor and the calculated voltage command value are stored in a memory in association with each other,
Based on the current rotation state, the voltage command value is newly calculated,
An inverter control device that sets a lower value of the newly calculated voltage command value and the voltage command value stored in the memory as the demagnetization determination threshold value.
In a vehicle drive system provided with the inverter control device according to claim 1 or 2,
A vehicle drive system comprising a clutch connecting between the motor and a vehicle axle, wherein the controller determines whether or not demagnetization of the magnet is occurring in a state where the clutch is disconnected.
A vehicle drive system comprising the inverter control device according to any one of claims 1 to 3,
A vehicle drive system comprising a continuously variable transmission that connects between the motor and a vehicle axle, wherein the controller controls the continuously variable transmission.