JP2004064956A - Inverter system for driving polyphase motor and its controlling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To sustain an appropriate control when the voltmeter in an auxiliary battery line becomes abnormal. <P>SOLUTION: Neutral of a motor 14 is connected with the positive electrode of an auxiliary battery 18 and an auxiliary load 20. Voltage of a feeder line to the auxiliary load 20 is detected by means of a voltmeter 22 and fed to a control circuit 24 in order to control the neutral voltage. When the voltmeter 22 becomes unavailable, current level of an ammeter 26 measuring the current of the auxiliary battery 18 is controlled to become 0 thus sustaining control of the neutral voltage. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an inverter system for driving a multi-phase motor including an AC motor driven by an inverter and generating power, and a power supply connected to a neutral point of the AC motor.
[0002]
[Prior art]
Conventionally, AC motors have been widely used as a power source for various devices. Even in electric vehicles and hybrid vehicles, normally, DC power from a battery is converted into desired AC power by an inverter and supplied to the motor. System is adopted. This system has the advantage that the output torque can be controlled over a wide range and the electric power by regenerative braking can be used for charging the battery.
[0003]
Here, a high-voltage motor is highly efficient as a power source for a high-output motor. For an electric vehicle or a hybrid vehicle, a high-voltage battery of several hundred volts is used as a main battery connected to the input side of the inverter. I have. On the other hand, at the neutral point of the star-connected motor coil, a voltage half of the inverter input voltage is normally obtained. Therefore, by connecting a battery to this neutral point, it is possible to output two types of DC voltage from the system, and to control the transfer of power between the two batteries by, for example, chopper controlling the motor coil. You can also.
[0004]
Therefore, in a hybrid vehicle or the like, by using the motor as a generator, a system for obtaining two power supply voltages by using the generated power to charge two batteries can be adopted. In particular, a capacitor can be used instead of a battery. Such a system is disclosed in Japanese Patent Application Laid-Open No. H11-178114.
[0005]
Here, various electric devices are mounted on the vehicle, and about 12 V (about 14 V at the time of charging) of these auxiliary batteries is usually mounted. The voltage at the motor neutral point described above is about one half of the voltage at the inverter input side, and in a normal electric vehicle or hybrid vehicle, even a neutral point voltage becomes a considerably high voltage. It is difficult to connect to. Therefore, a DCDC converter provided separately is used to charge the auxiliary battery.
[0006]
On the other hand, as a practical application example of such a system, a so-called dual power supply system having a 36V power supply and a 12V power supply has been studied. In this two-power supply system, the inverter input voltage is set to about 42 V when charging the 36 V power supply, and the neutral point voltage may be set to about 14 V when charging the 12 V power supply. Power can be transferred between power sources.
[0007]
Therefore, according to this inverter system, the electric charge can be transferred between the high-voltage side battery and the low-voltage side battery using the motor coil, and there is an advantage that a DCDC converter is not required.
[0008]
Here, in the inverter system for driving a multiphase motor as described above, a large number of auxiliary loads are connected to the low-voltage battery, and the low-voltage battery supplies power to these auxiliary loads stably. Playing a role. Then, in order to maintain the state of charge of the low-voltage battery at a predetermined state, the low-voltage battery is connected to the power generated in accordance with the power used in the auxiliary load connected to the low-voltage battery. Power supply line. For this purpose, conventionally, the voltage of the low-voltage side power supply line is sensed, and the power generated by the motor is feedback-controlled so that this voltage is constant.
[0009]
[Problems to be solved by the invention]
However, when the voltage sensing of the low-voltage side power supply line becomes abnormal due to disconnection or the like, there is a problem that the generated power cannot be controlled, and the generated voltage becomes overvoltage or low voltage.
[0010]
The present invention has been made in view of the above problems, and has as its object to provide a multiphase motor drive inverter system capable of performing appropriate power generation control even when an abnormality occurs in sensing of a low-voltage-side power supply line. .
[0011]
[Means for Solving the Problems]
The present invention includes an AC motor driven by an inverter to output driving power and generate power, and a power supply connected to a neutral point of the AC motor, and the power supply is charged by generated power of the AC motor. In addition, in a multi-phase motor drive inverter system that supplies power from the power supply to a plurality of electrical devices, power supply line voltage detection means for detecting the voltage of the power supply, power supply current detection means for detecting the current of the power supply, And normally controls an inverter according to the output of the power supply line voltage detection means, and controls the inverter according to the output of the power supply current detection means when the power supply line voltage detection means is abnormal. And
[0012]
If the voltage of the power supply connected to the neutral point of the motor cannot be measured, the neutral point voltage of the inverter cannot be controlled, but according to the present invention, the feedback control can be continued by the power supply current.
[0013]
Further, it is preferable that, when the power supply line voltage detection means is abnormal, control is performed so that the power supply current becomes 0 according to the output of the power supply current detection means. The power supply current is the difference between the neutral point current of the motor and the current consumption of the auxiliary load connected to the power supply. If this is 0, the charge capacity of the power supply does not change and proper neutral point voltage control is performed. I can do it.
[0014]
The present invention also includes an AC motor driven by an inverter to output driving power and generate power, and a power supply connected to a neutral point of the AC motor, and the power supply is generated by the AC motor. In a multi-phase motor driving inverter system for charging and supplying power to a plurality of electric devices from the power supply, a power supply line voltage detection means for detecting a voltage of the power supply; Neutral point current detecting means for detecting a neutral point current, and normally controls an inverter in accordance with the output of the power line voltage detecting means, and the neutral point when the power line voltage detecting means is abnormal. The inverter is controlled according to the output of the current detecting means.
[0015]
The neutral point current may be equal to the total current consumption in the auxiliary load and the like. Therefore, by controlling the neutral point current to match the current consumption of the auxiliary load, appropriate inverter control can be performed. In addition, the current consumption of the auxiliary load is usually unknown. Therefore, it is preferable that the minimum current consumption of the entire accessory load is detected in advance, and this is set as the target value of the neutral point current. Thus, overcharging of the power supply can be reliably prevented, and rapid discharge of the power supply can be prevented.
[0016]
Further, it is preferable that the neutral point current detecting means detects three-phase currents of the AC motor, and detects a neutral point current based on the detected values. The three-phase current of the AC motor is information necessary for drive control of the motor, and is originally provided in the system. Therefore, this control can be performed without adding a special sensor.
[0017]
The present invention includes an AC motor driven by an inverter to output driving power and generate power, and a power supply connected to a neutral point of the AC motor, and the power supply is charged by generated power of the AC motor. And a power line voltage detecting means for detecting a voltage of the power supply in a multi-phase motor driving inverter system for supplying power from the power supply to a plurality of electric devices, and the power line voltage detecting means in a normal state. And controlling the inverter according to a neutral point voltage command corresponding to a target voltage of the power supply when the power supply line voltage detecting means is abnormal.
[0018]
The neutral point voltage is a voltage appropriate as a power supply voltage of the auxiliary load. Therefore, for example, by setting the voltage to 14 V or the like, the control can be temporarily performed in a simple manner.
[0019]
Further, it is preferable that the neutral point voltage command is corrected based on at least one of a rotation speed of the AC motor, an output torque command, and an inverter input side voltage. Thus, the control can be corrected in accordance with the operation state of the motor.
[0020]
The present invention also relates to a control method of the system as described above and a program for executing the control.
[0021]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0022]
FIG. 1 is a diagram illustrating an overall configuration of an inverter system for driving a multiphase motor according to an embodiment. An inverter 12 is connected to a battery 10 as a main power supply. That is, the output of the battery 10 is applied between the positive bus and the negative bus of the inverter 12. The output voltage Vbm of the battery 10 is 36 V (42 V during charging).
[0023]
The inverter 12 has, for example, three arms in which two switching elements (transistors) are arranged in parallel between a positive bus and a negative bus, and a three-phase motor output terminal is provided between the transistors of each arm.
[0024]
The three-phase motor output terminal of this inverter is connected to the three-phase motor coil terminal of the three-phase AC motor 14. Therefore, one upper transistor of the inverter 12 is sequentially turned on, and while the one upper transistor is turned on, the transistors of the other arm are sequentially turned on. Supply motor current.
[0025]
A positive electrode of an auxiliary battery 18 and various auxiliary loads 20 are connected to a neutral point of the AC motor 14 via a reactor 16. A voltmeter 22 for detecting the voltage of the power supply line of the auxiliary battery 18 on the auxiliary battery 18 side from the reactor 16 is provided, and the output of the voltmeter 22 (battery voltage: Vbs) is supplied to the control circuit 24. Have been. The output voltage Vbs of the auxiliary battery 18 is 12 V (14 V during charging).
[0026]
An ammeter 26 for detecting the current (battery current: Ibs) of the auxiliary battery 18 is provided between the auxiliary battery 18 and the power supply line, and its output is also input to the control circuit 24.
[0027]
The control circuit 24 normally controls the switching of the inverter 12 based on the output Vbs of the voltmeter 22 to control the current supplied to the motor 14, so that the voltage Vbs becomes a desired value (for example, 14 V). The power generation of the motor 14 is controlled so that
[0028]
Here, in the control circuit 24, a countermeasure at the time of abnormality as shown in FIG. 2 is performed. It is determined whether there is an abnormality in voltage sensing of the power supply line (14V power supply line) to which the auxiliary battery 18 is connected (S11). This is determined by whether or not the output Vbs from the voltmeter 22 is a normal value. For example, if this voltage is a voltage of 8 V or less, normal driving of various accessory loads cannot be performed, and in such a case, it is determined that the load is abnormal. In particular, if Vbs is 0 V, there is some failure.
[0029]
If the determination in S11 is NO, there is no problem, and the switching of the inverter 12 is controlled based on the detected Vbs (14V system voltage) (S12).
[0030]
On the other hand, if it is determined in S11 that there is an abnormality, an abnormality warning is issued (S13). For example, a display indicating a 14V system battery sensing error is displayed on the display panel, or an auxiliary battery error lamp is turned on.
[0031]
Then, the detection value Ibs of the ammeter 26 is detected. This Ibs is the difference between the current flowing through the auxiliary load and the neutral point current. Therefore, by controlling the inverter 12 so that this Ibs becomes 0, the power used by the auxiliary load and the power generated by the motor 14 can be matched. Therefore, in the present embodiment, the inverter 12 is controlled so that the current Ibs becomes 0.
[0032]
When the voltage sensing of the 14V system becomes abnormal, the feedback control cannot be performed, and the generated voltage largely deviates from the correct target voltage, which may cause an overvoltage or a voltage drop. In this case, the auxiliary battery 18 cannot be driven due to overcharging or rapid discharge, and the auxiliary load has a malfunction due to an overvoltage, a malfunction due to a voltage drop, and a reset of the CPU. appear. In the present embodiment, since the feedback control is performed based on the sensing of the current Ibs, the power generated by the motor 14 can be maintained at a substantially correct level. Therefore, it is possible to prevent the above-described problem from occurring. In addition, by issuing an abnormality warning, voltage sensing can be restored at an appropriate timing, and a normal state can be restored before a major problem occurs.
[0033]
FIG. 3 shows the configuration of the control circuit 24. The voltage Vbm of the battery 10 on the high voltage side is measured, and the difference from the target voltage Vbm is supplied to the Vbm feedback (F / B) unit 30. The Vbm feedback (F / B) unit 30 determines the torque command Tmg * of the motor 14 so that the battery 10 voltage Vbm becomes the double-table voltage Vbm *, and supplies the same to the switching calculation unit 32. Note that the torque command Tmg * corresponds to a generated power command of the motor 14.
[0034]
The switching operation unit 32 is also supplied with the phase coil currents Iu, Iv, Iw of the motor 14 and the detection signal θ about the rotor position, and according to these signals Su controls the switching of the switching elements of each phase of the inverter. , Sv, and Sw, thereby controlling each phase current of the motor 14. Thereby, control is performed so that the output torque (power generation) of the motor 14 matches the torque command Tmg *.
[0035]
Here, the command value Vn of the neutral point voltage of the motor 14 is supplied to the switching operation unit 32, whereby the ratio of the ON period of the upper switching element to the lower switching element of the inverter is controlled. The voltage is controlled.
[0036]
The neutral point voltage Vn supplies the difference between the normal-time auxiliary battery 18 voltage Vbs and its command value Vbs * to the feedback (F / B) unit 36 via the switching unit 34, whereby Vbs becomes Vbs. Vn is determined to match *. However, if it is determined in S11 in FIG. 2 that there is an abnormality, a switching signal is output in S14, whereby the switching unit 34 feeds back the difference between the auxiliary battery current Ibs and its command value Ibs * ( F / B) unit 36. Accordingly, in the feedback (F / B) unit 36, Vn is generated based on the current Ibs of the auxiliary battery, and the switching operation unit 32 controls the switching of the inverter 12 based on this Vn. Is controlled to a voltage corresponding to the power consumption of the auxiliary load.
[0037]
Here, control of the neutral point voltage Vn and the battery 10 voltage Vbm will be briefly described.
[0038]
In this system, the neutral point voltage is controlled by changing the ratio of the on-duty of the upper transistor to the on-duty of the lower transistor in the inverter 12. That is, if both ON periods are the same, the neutral point voltage becomes equal to the inverter input voltage (battery 10 voltage). On the other hand, if the ON period of the upper transistor is “2” with respect to the ON period of the lower transistor “1”, the neutral point voltage is １ ／ of the voltage of the battery 10.
[0039]
For example, when the voltage of the battery 10 is 36 V (42 V at the time of charging), the voltage of the auxiliary battery 18 is 12 V (14 V at the time of charging). Then, the AC motor 14 is driven by the electric power from the battery 10 to perform torque assist such as when starting the vehicle, and the various auxiliary loads 20 are operated by the electric power from the auxiliary battery 18.
[0040]
Here, in order to control the neutral point voltage to be 1/3 of the battery 10 voltage, the on-periods of the upper transistor and the lower transistor in the inverter 12 are unbalanced, and the neutral point voltage is It will oscillate according to the current supply phase to each phase. The reactor 16 plays a role of smoothing the oscillating neutral point voltage to some extent, and the output voltage of the auxiliary battery 18 is maintained at a substantially constant value by the auxiliary battery 18.
[0041]
FIG. 4 shows a configuration of another embodiment. In this example, instead of the ammeter 26, ammeters 28u, 28v, and 29w that measure the current of each phase coil of the motor are employed. Here, as shown in FIG. 3 described above, the phase coil currents Iu, Iv, Iw of the motor 14 are necessary for calculating the torque command Tmg *, and these ammeters 28u, 28v, 28w are originally provided. ing. In this embodiment, each phase coil current is used.
[0042]
Here, if there is no neutral point current, the sum of the coil currents of each phase should be zero. Therefore, the sum of the coil currents Iu, Iv, Iw of each phase becomes the neutral point current In. If the neutral point current In is controlled so as to match the current consumption of the entire auxiliary load connected to the 14V power supply line, correct power generation is supplied to the 14V power supply. Therefore, the current consumption of the auxiliary load is measured, the target value In * of the neutral point current is determined based on the measured current, and control is performed so that the neutral point current In matches In *.
[0043]
However, generally, it is not possible to measure the current consumption in all the auxiliary loads. Therefore, in the present embodiment, the minimum current consumption of the entire accessory load is checked in advance, and this minimum current consumption is set as the target neutral point current In *.
[0044]
Thus, overcharging of the auxiliary battery 18 can be prevented. When the current consumption in the auxiliary load increases, the auxiliary battery 18 cannot be dealt with and the auxiliary battery 18 is discharged. However, it is possible to prevent the auxiliary battery 18 from being rapidly discharged.
[0045]
FIG. 5 shows the configuration of the control circuit 24 in this embodiment. As described above, in the event of an abnormality, the switching unit 34 selects the difference (In * −In) from the target value of the neutral point current, and supplies the difference (In * −In) to the feedback (F / B) unit 36. Then, the feedback (F / B) unit 36 creates the neutral point voltage target value Vn and supplies it to the switching operation unit 32.
[0046]
Further, as a simple method, the neutral point voltage command Vn is calculated by open-loop feedforward control without feeding back the battery current or the neutral point current. For example, the neutral point voltage command Vn is set to 14V. As a result, although the accuracy of the control of the generated voltage is reduced, an improved control can be performed as compared with a case where no control is performed.
[0047]
FIG. 6 shows an example in which the accuracy is increased in the open loop control. In this example, normally, the difference between the accessory load power supply line voltage command Vbs * and the voltage Vbs is input to the control circuit 24, and the control of the inverter 12 is corrected based on these.
[0048]
FIG. 7 shows a configuration of the control circuit 24 of the present embodiment.
[0049]
The difference between the auxiliary load power supply line voltage command Vbs * and the voltage Vbs is input to a feedback (F / B) section, where a neutral point voltage command Vn is created, and this is switched via a switching section 34 to a switching operation section 32. To supply. On the other hand, when abnormal, the motor rotation speed Nmg, the motor output torque command Tmg *, and the battery 10 voltage Vbm are input to the map 38, and the corrected neutral point voltage command Vn is output. This output is supplied to the switching operation unit 32 via the switching unit 34.
[0050]
As a result, in the event of an abnormality, Vn can be corrected based on the operating state at that time and the like, and inverter drive control more in line with the current situation can be performed.
[0051]
Here, it is preferable that the AC motor 14 of the present embodiment is for a vehicle mounted on a vehicle. The accessory load 20 includes various accessories mounted on the vehicle. Further, as the AC motor 14 mounted on a vehicle, a motor generator for an eco-run system described in JP-A-2002-155773 is suitable.
[0052]
That is, the motor generator runs (i) the vehicle running while automatically starting the engine at the time of starting after performing idle stop control for stopping the engine while the vehicle is stopped, and (ii) via the drive system at the time of vehicle deceleration. Regenerative power generation performed by transmitting the rotation of wheels, (iii) driving of an air conditioner compressor or a power steering pump when the engine is stopped due to vehicle stop, (iv) power generation when the engine is driven, and (v) operation. Control to suppress the generation of vibration when the engine is stopped by controlling the rotation of the stopped engine. (Vi) Prevent engine stall that cuts fuel supply to the engine during deceleration and then recovers the engine speed when fuel supply is started. Used for, for example.
[0053]
【The invention's effect】
As described above, according to the present invention, when the voltage of the power supply connected to the motor neutral point cannot be measured, the feedback control can be continued by the power supply current.
[0054]
In addition, by controlling the neutral point current to match the current consumption of the auxiliary load, appropriate inverter control can be performed.
[0055]
Further, by setting the neutral point voltage to an appropriate voltage as the power supply voltage of the auxiliary load, the control can be continued by a simple method.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a system according to an embodiment.
FIG. 2 is a flowchart illustrating an operation of the embodiment of the embodiment.
FIG. 3 is a diagram showing a configuration of a control circuit of the embodiment.
FIG. 4 is a diagram showing a configuration of a system according to another embodiment.
FIG. 5 is a diagram showing a configuration of a control circuit of the embodiment.
FIG. 6 is a diagram showing a system configuration according to still another embodiment.
FIG. 7 is a diagram showing a configuration of a control circuit of the embodiment.
[Explanation of symbols]
Reference Signs List 10 main battery, 12 inverter, 14 AC motor, 16 reactor, 18 auxiliary battery, 20 auxiliary load, 22 voltmeter, 24 control circuit, 32
Switching operation unit, 34 switching unit, 36 feedback (F / B) unit.

Claims (11)

An AC motor driven by an inverter to generate driving force output and power generation, and a power supply connected to a neutral point of the AC motor; and charging the power supply with power generated by the AC motor; In a multi-phase motor drive inverter system that supplies power to multiple electrical devices from
Power supply line voltage detection means for detecting the voltage of the power supply line to which the power supply is connected,
Power supply current detection means for detecting the current of the power supply,
Has,
An inverter system for driving a multiphase motor that normally controls an inverter according to the output of the power supply line voltage detection means, and controls the inverter according to the output of the power supply current detection means when the power supply line voltage detection means is abnormal. . The system according to claim 1,
An inverter system for driving a multi-phase motor for controlling the power supply current to be 0 according to the output of the power supply current detection means when the power supply line voltage detection means is abnormal. An AC motor driven by an inverter to generate driving force output and power generation, and a power supply connected to a neutral point of the AC motor; and charging the power supply with power generated by the AC motor; In a multi-phase motor drive inverter system that supplies power to multiple electrical devices from
Power supply line voltage detection means for detecting the voltage of the power supply line to which the power supply is connected,
Neutral point current detecting means for detecting a neutral point current flowing into and out of the neutral point of the AC motor,
Has,
Normally, the inverter is controlled in accordance with the output of the power line voltage detecting means, and when the power line voltage detecting means is abnormal, the inverter is controlled in accordance with the output of the neutral point current detecting means. Inverter system. The system according to claim 3,
An inverter system for driving a multi-phase motor, wherein the neutral point current detecting means detects a three-phase current of the AC motor, respectively, and detects a neutral point current based on the detected value. An AC motor driven by an inverter to generate driving force output and power generation, and a power supply connected to a neutral point of the AC motor; and charging the power supply with power generated by the AC motor; In a multi-phase motor drive inverter system that supplies power to multiple electrical devices from
Power supply line voltage detection means for detecting the voltage of the power supply line to which the power supply is connected,
Has,
Normally, the inverter is controlled in accordance with the output of the power line voltage detecting means, and when the power line voltage detecting means is abnormal, the inverter is controlled in accordance with a neutral point voltage command corresponding to the target voltage of the power supply. Inverter system for driving a phase motor. The system according to claim 5,
An inverter system for driving a multi-phase motor, wherein the neutral point voltage command is corrected based on at least one of a rotation speed of the AC motor, an output torque command, and an inverter input side voltage. An AC motor driven by an inverter to generate driving force output and power generation, and a power supply connected to a neutral point of the AC motor; and charging the power supply with power generated by the AC motor; In the control method of the inverter system for driving a multi-phase motor that supplies power to a plurality of electric devices from the
An inverter system for driving a multiphase motor that normally controls an inverter according to the voltage of a power supply line to which the power supply is connected, and controls the inverter according to the current of the power supply when detection of the power supply line voltage is abnormal. Control method. An AC motor driven by an inverter to generate driving force output and power generation, and a power supply connected to a neutral point of the AC motor; and charging the power supply with power generated by the AC motor; In the control method of the inverter system for driving a multi-phase motor that supplies power to a plurality of electric devices from the
A multi-phase motor driving inverter system that controls an inverter according to the voltage of a power supply line to which the power supply is connected at normal times, and controls the inverter according to the current at the neutral point when the power supply line voltage detection is abnormal. Control method. An AC motor driven by an inverter to generate driving force output and power generation, and a power supply connected to a neutral point of the AC motor; and charging the power supply with power generated by the AC motor; In the control method of the inverter system for driving a multi-phase motor that supplies power to a plurality of electric devices from the
A multi-phase motor drive inverter system that controls an inverter according to the voltage of the power supply during normal times, and controls the inverter according to a neutral point voltage command corresponding to a target voltage of the power supply when the power supply line voltage is abnormal. Control method. A control program for a polyphase motor drive inverter system, the control program causing a system to execute the control method for a polyphase motor drive inverter system according to any one of claims 7 to 9. The system, method, or program according to any one of claims 1 to 10,
A multi-phase motor drive inverter system, wherein the AC motor is a vehicle AC motor, a control method of a multi-phase motor drive inverter, or a control program of a multi-phase motor drive inverter system.

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