JPH10304676A - Discharging device of inverter internal capacitor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharging device which permits the charge of a smoothing capacitor to be consumptively-discharged at the coil of a permanent magnet motor, while eliminating rattles in a gear at the rotation of a motor. SOLUTION: At the same time as when stopping of an inverter 12 due to IG(ignition) off is detected by a stopping detection part 16a, an IG off timer 16b is incremented. When a rotation detection part 16d detects a stopping position based on the detected results of a rotor position sensor 18, a discharge controller 16c determines the vector direction of discharge current to start discharging control. When the discharge controller 16c performs discharging, a discharge current amount is increased gradually from zero, and even when torque occurs at a rotor, the initial rotational force of the motor is relieved to reduce gear collision and relieve or eliminate rattles.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for stopping an inverter connected to supply AC power to an AC motor.
The present invention relates to an improvement of a discharge device that consumes electric charge remaining in a smoothing capacitor inside the inverter.

[0002]

2. Description of the Related Art When an AC motor is driven by a DC power supply,
For example, when driving a motor of an electric vehicle, power conversion means for converting DC power supplied from a battery or the like to AC power is required, and an inverter is used for this power conversion means. On the input side of the inverter, that is, on the DC power supply side, power storage means (generally, a capacitor, hereinafter referred to as a smoothing capacitor) for smoothing the output of the DC power supply is provided. In the case of an electric vehicle, the capacity of the smoothing capacitor used is large, and may be several thousand μF. When the electric vehicle is in a driving state, a voltage is constantly applied to the smoothing capacitor and charging and discharging are repeated. The relay disposed therebetween opens at the same time as the IGoff, and at the same time, the control of the inverter stops, so that electric charges remain in the smoothing capacitor and cannot be removed. Usually IGoff
After a long period of time, the residual charge on the smoothing capacitor will be discharged spontaneously. Since the operation becomes difficult, it is preferable to discharge the residual charges promptly.

The simplest method for discharging is a method using a discharge resistor. For example, there is a method of opening a relay between a DC power supply and an inverter, and simultaneously inserting a discharge resistor into a circuit to discharge from a smoothing capacitor. If the power consumption by the discharge resistor does not matter much, the discharge resistor may be always inserted in the circuit. However, such a method requires a discharge resistor and a means (for example, a relay) for inserting the discharge resistor into a circuit, and is not suitable for miniaturization, simplification, and high reliability of the device configuration. In order to eliminate such a problem, Japanese Patent Application Laid-Open No. Sho 59-172368 discloses that the inverter is operated separately after the relay between the DC power supply and the inverter is opened, and the current is supplied from the smoothing capacitor to the motor coil. ing. That is, the electric charge remaining in the smoothing capacitor is consumed as Joule heat by the resistance of the motor coil.

[0004]

When the smoothing capacitor is discharged using the resistance of the motor coil as described above, it is necessary to control the operation of the inverter so that the motor does not rotate. Since the motor used in JP-A-59-172368 is an induction motor, a current may be applied to the windings so that a magnetic field does not alternate in the motor.
However, when a permanent magnet motor, that is, a synchronous motor excited by a permanent magnet, is used as a motor, the position of the permanent magnet (rotor) is detected by a sensor such as a resolver so that a magnetic field does not alternate in the motor. It is necessary to supply current to the coil.

However, since the sensor such as the resolver always includes an error, it is impossible to accurately detect the position of the rotor, and the rotation of the motor cannot be completely stopped. That is, torque is applied to the motor due to the linkage between the magnetic field generated by the permanent magnet and the magnetic field generated by the coil current. Although the torque generated in this manner is not so large, there is a problem that vibration is generated in the motor, and the tooth surface of the drive system gear connected to the motor collides, resulting in generation of rattling noise. In particular, in an electric vehicle or the like, a rattling sound is generated after the vehicle stops, which gives the user discomfort.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and an improvement in a method of controlling an inverter after disconnection from a DC power supply has reduced the rattle of gears caused by rotation of a motor. It is an object of the present invention to provide a discharge device capable of consuming and discharging the charge of a smoothing capacitor in a coil of a permanent magnet motor while eliminating the charge.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above object, a configuration of the present invention is to stop an inverter for converting DC power from a power supply into AC power in order to supply drive power to a motor. A discharge detector for discharging the electric charge remaining in the smoothing capacitor provided in the inverter with the coil of the motor at the time of the inverter; A discharge control unit for gradually increasing the discharge amount of the discharge means from zero based on the discharge control unit.

According to this configuration, even when a torque is generated in the motor by the discharge control, the motor gradually starts to rotate from the stop state, so that the tooth surfaces of the drive system gears come into contact with each other in the low-speed rotation section of the motor. Therefore, occurrence of rattling noise can be eliminated.

Further, in order to achieve the above object, the configuration of the present invention provides a configuration in which the inverter for converting the DC power from the power supply device into the AC power for supplying the driving power to the motor is stopped when the inverter is stopped. A discharge device for an internal capacitor of an inverter having a discharge unit for discharging electric charge remaining in a smoothing capacitor provided by a coil of the motor, a stop detection unit for detecting a stop of the inverter, And a correction unit that corrects an electrical angle of a current discharged by the discharging unit based on the rotation of the motor.

Here, the rotation detecting section is, for example, a sensor such as a resolver, which can detect at least the amount of rotation and the direction of rotation of the motor. This is to correct the electrical angle of the discharge current so as to generate a torque in the direction of suppressing rotation.

According to this configuration, the rotation detecting section constantly recognizes the detection error, and discharges the current in a direction to suppress the rotation of the motor based on the error to reduce the rotation of the motor based on the error. . That is, since the rotation suppression control is performed at the initial stage of the discharge control, the rotation of the motor can be minimized, and the rattling noise between the drive system gears can be eliminated.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention (hereinafter referred to as embodiments) will be described below with reference to the drawings.

Embodiment 1 FIG. 1A shows a system configuration of an electric vehicle according to an embodiment of the present invention. The electric vehicle shown in this figure uses a permanent magnet motor as a motor 10 for running the vehicle. The driving power of the motor 10 is supplied to the battery 1 via the inverter 12.
4 is provided. That is, the discharge output of the battery 14 is converted into three-phase alternating current by the inverter 12 and supplied to each phase winding (coil) of the motor 10. The inverter 12 includes a plurality of switching elements (for example, IGBTs) for converting power from DC to three-phase AC.
In addition, a smoothing capacitor C for smoothing the output of the battery 14 is incorporated. In the present embodiment, as described later, the smoothing capacitor C
Therefore, a resistor or the like for discharging is not required.

The operation of the inverter 12 is controlled by an electronic control unit (hereinafter referred to as ECU) 16. EC
U16 starts operating when the ignition switch is turned on, and an accelerator signal supplied from each circuit,
A torque command is calculated based on a brake signal, a shift position signal, and the like. The ECU 16 generates a pulse width modulation (PWM) signal based on the calculated torque command, and controls the switching operation of each switching element included in the inverter 12 based on the generated PWM signal. ECU16
When such control is performed, a rotor sensor signal which is an output of a rotor position sensor 18 attached to the motor 10, for example, a resolver and indicates a position θ of a rotor (rotor) of the motor 10, A feedback signal of each phase current Iu, Iv, Iw supplied from the inverter 12 to the motor 10, a signal indicating the voltage of the battery 14,
2 is input with a signal indicating the input voltage VINV. ECU
The ECU 16 further controls the relay unit 20 provided between the battery 14 and the inverter 12 to open and close the connection between the battery 14 and the inverter 12, and controls the relay 22 to control the ECU 16 and the inverter 12. Of the control power supply (+ 12V) to the power supply.

FIG. 1B shows an example of E applied to the first embodiment.
The outline of the internal configuration of the CU 16A (only the characteristic configuration used in the first embodiment is shown) is shown. A characteristic feature of the first embodiment is that when the operation of the inverter 12 is stopped, the electric charge remaining in the smoothing capacitor C is discharged by each layer coil of the motor 10. At that time, the discharge amount is gradually increased from zero.

In the ECU 16A, as shown in FIG. 1B, normal control of the inverter 12 and the like (during a drive (D) range or a reverse (R) range of an electric vehicle) is performed based on the input signals described above. In addition to a control unit (not shown) that performs control of driving the motor with the accelerator on to make the vehicle run, a stop detection unit 16a that detects a stop instruction signal of the inverter 12 (in this embodiment, detection of an off operation of the ignition SW) ), An IGoff timer 16b that starts operation based on the stop detection of the stop detection unit 16a,
During the operation of the IGoff timer 16b, a discharge control unit 16c that generates a PWM signal to discharge the charge remaining in the smoothing capacitor C and controls the switching operation of each switching element included in the inverter 12, A rotation detector 16d for detecting the amount and direction of rotation of the rotor for determining the vector direction of the discharge current of the discharge controller 16c based on the detection result of the sensor 18 is included.

Next, discharge control based on the configuration of the ECU 16A shown in FIG. 1B will be described with reference to the flowchart of FIG. 2 and the transition graph of the discharge current value of FIG. Note that FIG.
It is assumed that the control of the flowchart shown in FIG.

First, the stop detecting unit 16a determines whether or not IGoff is performed at a predetermined cycle (for example, a torque command calculation cycle (= current command value calculation cycle) of 5 ms) (S10).
0). If not IGoff, that is, if the IG key
When the electric vehicle is in the ON state when inserted into the cylinder and the traveling state or the traveling preparation state of the electric vehicle is maintained, normal control is performed on the inverter 12 (S101). The normal control includes a drive (D) range, a reverse (R)
In the range, control is performed to generate a torque in the motor 10 with the accelerator on to make the vehicle run. Then, in the next cycle, it is determined again whether or not IGoff is performed. If (S10
If the IGoff is confirmed in 0), that is, if the user turns off the IG key to stop or park the vehicle, the ECU 16A opens the relay of the relay unit 20, disconnects the connection between the inverter 12 and the battery 14, and , IGoff timer 16b is incremented (+
1) Then (S102), the discharge control of the smoothing capacitor C by the discharge control unit 16c is started. In the discharge control performed at this time, based on the detection result of the rotor position sensor 18, the discharge control unit 16c determines the vector direction of the discharge current based on the rotor stop position calculated by the rotation detection unit 16d. That is, the discharge is controlled so that the vector of the discharge current is directed in a direction parallel to the d-axis (the direction of the magnetic field formed by the rotor of the motor). As a result, no torque is generated on the q axis (the direction of the vector in which the torque is generated). However, as described above, since the rotor position sensor 18 includes an error, the actual direction of the d-axis (rotor) does not match the direction (position) of the rotor recognized by the sensor, and torque is generated. Resulting in.

Therefore, the discharge control section 16c starts the discharge of the electric charge remaining in the smoothing capacitor C and, at the same time, performs control to gradually increase the discharge amount from zero (S103). The change of the discharge amount at this time is, for example, as shown in FIG. 3A, a method of increasing the discharge amount by the square of the time t, or as shown in FIG. There is a method of linearly increasing the discharge amount based on the above. When the discharge amount increasing process for one cycle is completed, the IGoff timer 16
It is determined whether the increment value of b has exceeded the set value (S104).

The above-mentioned set value means that after the IG key is turned off, how much time elapses before the smoothing capacitor C
Of the residual charge of the
This is a value for determining whether to turn off the power supply of the ECU 16A, and the OFF time (for example, 1.0 second) of the ECU 16A is determined by the processing cycle and the increment value described above. IGof
If the increment value of the f-timer 16b has not exceeded the set value, the process returns to (S102) and the subsequent processes are repeated. Usually, once IGoff is confirmed, IGoff
The timer is sequentially incremented, and the discharge current amount of the smoothing capacitor C increases. In any of the above-described methods of increasing the amount of discharge, it is necessary to set the gradient of increase in the amount of discharge so that the tooth surfaces of the drive system gears contact each other at the initial stage of torque generation. That is, the section A shown in FIG.
The contact between the tooth surfaces of the drive system gears is performed while the amount of discharge is small in the vicinity of (while the generated torque is small and the rotation is in the low speed range). As a result, rattling of the gear is reduced or eliminated. Since the contact between the tooth surfaces of the drive system gears is completed while the generated torque is small, the tooth surfaces of the drive system gears are already in contact with each other even if the discharge current increases in the section B in the latter half of the control. Electric discharge remaining in the smoothing capacitor C can be satisfactorily discharged without rattling noise.

On the other hand, if the increment value of the IGoff timer 16b exceeds the set value in (S104), it is determined that the discharge of the residual charge in the smoothing capacitor C has been completed, and the power supply of the ECU 16A is turned off (S105). . That is, the relay 22 is opened, the supply of the control power (+12 V) to the ECU 16A and the inverter 12 is stopped, and the entire control is ended.

When the control of increasing the discharge amount is performed, FIG.
As shown in FIG.
Compared to the case of performing based on the increasing straight line as shown in (b), the contact between the tooth surfaces of the drive system gear can be performed softly, and the rattling noise can be reduced or eliminated better. In addition, the calculation for creating the increase curve becomes complicated.
Therefore, a correspondence table in which the elapsed time from IGoff and the discharge amount are associated in advance is created, and the rate of increase in the discharge amount is changed for each cycle as shown in FIG. The increase curve of FIG. 3A can be artificially formed, and the calculation for discharge control can be simplified.

As described above, even when the torque is generated due to the error of the rotor position sensor and the motor rotates,
By gradually increasing the discharge variable flow rate from zero, the impact of contact between the tooth surfaces of the drive system gear is reduced, and the gear hitting noise is reduced,
Alternatively, exclusion can be easily performed.

Embodiment 2 FIG. The basic part of the system configuration of the electric vehicle according to the second embodiment is the same as that shown in FIG. 1A, but the configuration inside the ECU 16 is different. FIG.
(C) shows the internal configuration of the ECU 16B applied to the second embodiment. ECU 1 applied in the first embodiment
6A, the inverter 12 is provided inside the ECU 16B.
A stop detection unit 16a that detects a stop instruction signal of the inverter 12, in addition to a control unit (not shown) that performs normal control such as
PW to discharge the charge remaining in the smoothing capacitor C
A discharge control unit 16 that generates an M signal and controls the switching operation of each switching element forming the inverter 12
c, a rotation detection unit 16d for detecting the state (position or amount of rotation, rotation direction) of the rotor based on the detection result of the rotor position sensor 18, and the discharge based on the detection result of the rotation detection unit 16d. When the rotation of the motor is generated by the discharge performed by the control unit 16c, the control unit 16c includes an electric angle correction unit 16e that corrects the electric angle of the discharge current in a direction to suppress the rotation.

Hereinafter, the discharging process of the second embodiment will be described with reference to the flowcharts of FIGS. First,
As in the first embodiment, the stop detection unit 16a determines whether or not IGoff is performed at a predetermined cycle (S200). IGoff
If not, that is, if the IG key is inserted into the IG cylinder and is in the on state, and the traveling state or the traveling preparation state of the electric vehicle is maintained, the normal control is performed on the inverter 12 (S201). On the other hand, when IGoff is confirmed in (S200), that is, when the user turns off the IG key to stop or park the vehicle, E
The CU 16B opens the relay of the relay unit 20, disconnects the connection between the inverter 12 and the battery 14, and
The rotation detecting unit 16d recognizes the stop position of the rotor based on the detection value of the rotor position detection sensor 18 at the time of Goff. Then, the discharge control unit 16c performs the discharge control of the smoothing capacitor C of the inverter 12 based on the rotor stop position at the time of IGoff so that no torque is generated in the rotor (S202).

Subsequently, the rotation detector 16d monitors whether or not the rotor is displaced (rotated) by discharge control based on the stopped state of the rotor at the time of IGoff due to a detection error of the rotor position sensor 18 or the like. Is performed (S203). If the displacement of the rotor is not detected (S204), the ECU 16
B determines whether or not the charge remaining in the smoothing capacitor C has been completely discharged (S205). If the discharge has not been completed, the process returns to (S202) and performs the discharge process in the next cycle. When the ECU 16B confirms that the discharge of the smoothing capacitor C is completed, the ECU 16B turns off the power supply of the ECU 16B (S
206). That is, the relay 22 is opened and the ECU 16B
Then, the supply of the control power (+12 V) to the inverter 12 is stopped, and the entire control is terminated.

On the other hand, if it is confirmed in step (S204) that the rotor is displaced due to torque generated due to a detection error of the rotor position sensor 18 even though the current is discharged in a direction in which no torque is generated, The angle correction unit 16e corrects the detection value of the rotor position sensor 18 based on the displacement state of the rotor, that is, the rotation amount and the rotation direction, and performs correction to suppress the rotation of the rotor (S207). That is, the electrical angle correction unit 16e forms an arithmetic dq axis coordinate system based on the magnetic field formed by the rotor based on the rotor position at the time of IGoff, as shown in FIG. When performing the discharge control of (S202), the control of each switching element of the inverter 12 is performed so as to direct the vector of the discharge current in a direction parallel to the d axis on the dq axis coordinate system. Subsequently, when the rotation of the rotor stopped by the discharge is confirmed by the rotor position sensor 18, the dq axis coordinate system initially set due to the error of the rotor position sensor 18 is shifted. Upon recognition, the offset correction of the dq axis coordinate system is performed. For example, when it is confirmed by the rotor position sensor 18 that the rotor has rotated clockwise, the origin of the control electrical angle is corrected so that the dq axis coordinate system is rotated counterclockwise. Similarly,
When it is confirmed that the rotor has rotated in the counterclockwise direction, a correction for rotating and moving the dq axis coordinate system in the clockwise direction is performed. At this time, the control electric angle origin correction amount is obtained by setting the electric angle after correction to θ _{e0 (t)} and setting the electric angle before correction to θ _{e0 (t-1).}
When the amount of displacement of the electrical angle per unit time is Δθe, it can be expressed as the following equation.

Θ _{e0 (t)} = θ _{e0 (t−1)} + f ₍ Δθ _e) At this time, the function f is added as a correction amount by, for example, 0.3 times the displacement amount Δθe. Originally, when the rotation of the rotor starts, it is only necessary to control so that the torque of the same magnitude is generated in the opposite direction. However, since there is a risk of divergence, it is desirable to perform gradual correction in each control cycle. For this purpose, the function f is used. In the first correction process, θ
_{e0 (t-1)} is "zero". As a result, the corrected d-
Discharge control correction is performed based on the q-axis coordinate system (S20).
8) The amount of rotation of the rotor is reduced. Then the ECU
16B determines whether the discharge is completed (S20).
5) If not completed, return to (S203) and perform the discharging process in the next control cycle. When the ECU 16B confirms that the discharge of the smoothing capacitor C has been completed, the ECU 16B is turned off (S206), and the entire control is terminated.

As described above, even when a torque is generated in the rotor during the discharge control due to the error of the rotor position detection sensor 18, the electric angle correction control is performed so as to suppress the torque generated in each discharge control cycle. Is performed, the rotation of the motor is reduced, the impact of the contact between the tooth surfaces of the drive system gears is reduced, and the gear hitting noise can be easily reduced or eliminated.

In the second embodiment, the ECU 16B
A learning function for recognizing the inherent error amount of the rotor position sensor 18 and correcting the dq axis coordinate system in advance in the subsequent discharge control. Is also good.

Embodiment 3 In the above-described first and second embodiments, when the rotor state cannot be detected due to a failure of the rotor position sensor 18 or the like, good discharge control cannot be performed, and a large rattling noise may be generated. Therefore, the discharge control itself may be stopped based on the detection result of a sensor (for example, an optical sensor or a magnetic sensor for rotation detection disposed in a gear or the like to which the motor 10 is connected) disposed in another part. Can be In this case, for example,
What is necessary is just to perform control based on a flowchart as shown in FIG.

First, the ECU 16 determines whether or not the current control state is during the discharge control of the smoothing capacitor C after the operation of the inverter 12 is stopped (S300). When discharge control is not being performed, normal control is performed and motor 1 based on accelerator operation is operated.
0 is performed (S301). On the other hand, during the discharge control, the gear rotation angle is monitored by an optical sensor, a magnetic sensor, or the like (S302). The ECU 16 determines whether or not the rotation angle of the gear has changed by a set value or more from the start of the discharge control based on the monitoring result of the sensor (S303). If it is detected that the gear has rotated beyond the set value, it means that the discharge control performed while suppressing the rotation of the motor has not been performed well, and the discharge control is stopped immediately (S
304), the power supply of the ECU 16 is turned off (S30).
5). As a result, it is possible to prevent a large rattling sound from giving the user great discomfort.

On the other hand, if it is determined in (S303) that the gear rotation angle is equal to or smaller than the set value, the ECU 16 determines whether or not the discharge has been completed (S306). Returning to (S302), monitoring of the gear rotation angle is continuously performed. If the discharge has been completed, the power supply of the ECU 16 is turned off (S305), and the entire control ends.

As described above, by detecting the displacement of the driving parts other than the motor such as the gear, the unpleasant rattling noise after the vehicle stops can be reliably prevented.

[0035]

According to the present invention, even if there is an error or the like in the rotor position sensor of the motor and a torque is generated in the motor during the discharge control of the smoothing capacitor, the control method of the inverter improves the play of the motor. The charge of the smoothing capacitor can be satisfactorily consumed and discharged by the coil of the permanent magnet motor while eliminating the hitting sound.

[Brief description of the drawings]

FIG. 1 is a diagram showing a system configuration of an electric vehicle having a discharge device according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating discharge control according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram illustrating transition of a discharge current value in discharge control according to the first embodiment of the present invention.

FIG. 4 is a flowchart illustrating discharge control according to a second embodiment of the present invention.

FIG. 5 shows dq of discharge control according to Embodiment 2 of the present invention.
FIG. 4 is an explanatory diagram illustrating correction of an axis coordinate system.

FIG. 6 is a flowchart illustrating discharge control according to a third embodiment of the present invention.

[Explanation of symbols]

10 motors, 12 inverters, 14 batteries, 1
6, 16A, 16BECU, 16a Stop detector, 16
b IGoff timer, 16c Discharge control unit, 16d
Rotation detection unit, 16e Electric angle correction unit, 18 Rotor position sensor.

Claims (2)

[Claims] An electric charge remaining in a smoothing capacitor provided in the inverter is discharged by a coil of the motor when an inverter that converts DC power from a power supply device into AC power to supply driving power to the motor is stopped. A discharge device for discharging the internal capacitor of the inverter having a discharge unit for causing the discharge unit to have a stop detection unit that detects the stop of the inverter; and a discharge control unit that gradually increases the discharge amount of the discharge unit from zero based on the stop detection. A discharge device for an internal capacitor of an inverter. 2. A motor according to claim 1, wherein when the inverter for converting the DC power from the power supply to the AC power to supply the driving power to the motor is stopped, the electric charge remaining in the smoothing capacitor provided in the inverter is discharged by the coil of the motor. A discharge detecting device that detects a stop of the inverter; a rotation detecting unit that detects rotation of the motor based on the discharge after the stop of the inverter; and a rotation of the motor. Correction means for correcting the electrical angle of the current discharged by the discharging means based on the following.