JP2010193665A - Ac machine controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an AC machine controller capable of powering and regenerating an AC machine at a high efficiency within a battery protection range by effectively utilizing the battery and suppressing hunting. <P>SOLUTION: The AC machine controller includes: an adjusting torque operating section 8 for operating an adjustment torque by adjusting a request torque in controlling the AC machine by the maximum torque control, based on a difference (e) between a battery voltage VB of a battery for supplying power via an inverter circuit when the AC machine is powered and receiving the power via the inverter circuit when the AC machine is regenerated and storing the power, and a predetermined reference voltage VR; and a target torque switching section 9 for switching the target torque of the AC machine between the request torque and the adjustment torque when the battery voltage VB becomes a predetermined lower limit voltage or below when the AC machine is powered and it becomes a predetermined upper limit voltage or more when the AC machine is regenerated. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention converts a direct current power source fed from a battery into alternating current to drive an alternating current machine that functions as an alternating current motor, and converts the alternating current generated by the alternating current machine that functions as an alternating current generator into direct current. The present invention relates to an AC machine control device having at least one function of regenerating.

  In recent years, attention has been paid to the environmental load due to the consumption of fossil fuels, and various attempts have been made to reduce the environmental load even in automobiles in which a large number of engines are driven by an internal combustion engine that uses gasoline as fuel. An electric vehicle driven by a motor and a hybrid vehicle driven by an internal combustion engine and a motor are examples. A motor used in an electric vehicle or a hybrid vehicle is driven by receiving electric power from a storage battery (battery). When the motor output increases and the power consumption increases, the discharge from the battery also increases. In particular, if the discharge increases in a state where the remaining capacity of the battery is low, the battery may be overdischarged. When a battery is over-discharged, it can be damaged and its life can be significantly shortened. In order to prevent this, conventionally, when the voltage of the battery falls below a predetermined threshold value, the driving of the motor is stopped, and after the voltage of the battery is recovered by stopping the motor, the motor is driven again.

  However, even when the battery capacity is sufficiently large, for example, when rapid acceleration is performed, the output current may temporarily increase and the battery voltage may decrease. In the conventional configuration, the driving of the motor is stopped even in such a case. When the driving of the motor is stopped, the voltage of the battery having sufficient capacity is immediately recovered, so that the motor is driven again. On the other hand, when the acceleration request continues, a large amount of current is supplied again to the redriven motor, so that the voltage of the battery may drop and the driving of the motor may be stopped. That is, since driving and stopping of the motor are frequently repeated and vibration (hunting) is generated in the power of the vehicle, the comfortable driving is hindered.

  Japanese Patent Application Laid-Open No. 9-23512 (Patent Document 1) discloses a technique of a control device for an electric vehicle in view of this. This control device reduces the driving force of the motor when the voltage of the battery drops below the first threshold, and the battery voltage does not recover even if a predetermined time elapses after the driving force of the motor is reduced. Sometimes the driving force of the motor is further reduced. Further, the control device recovers the driving force of the motor when the voltage of the battery recovers to the second threshold value set to a voltage higher than the first threshold value.

JP-A-9-23512 (2nd to 7th paragraphs, etc.)

  The technique disclosed in Patent Document 1 is an excellent control method for eliminating hunting in view of conventional problems. However, since the driving force of the motor is limited based on the threshold value, the driving force of the motor is excessive until the battery voltage recovers to the second threshold value even if there is a margin in the battery output. Limited to In addition, although the motor is not stopped as in the prior art, when the battery voltage goes back and forth between the first threshold value and the second threshold value due to a sudden current fluctuation or the like, Hunting still occurs. There is a possibility that the driver may feel uncomfortable due to the fact that the battery cannot be effectively used within the operating voltage range of the battery and the torque requested by the driver is not output.

  It is said that a synchronous motor, which is a kind of AC motor, is most suitable for motors used for electric vehicles and hybrid vehicles in terms of weight, efficiency, maintainability, and the like. Since a battery mounted on an automobile is a direct current power source, an electric vehicle and a hybrid vehicle are configured to include an inverter circuit that converts direct current into alternating current. Since the synchronous motor can also function as a synchronous generator, hereinafter, the synchronous motor and the synchronous generator are collectively referred to as an AC machine. The generated AC power is converted to DC via an inverter circuit and regenerated to a battery as a storage battery, and the battery is charged. When the AC machine functions as a motor, that is, during power running, battery overdischarge becomes a problem as described above. On the other hand, when the alternator functions as a generator, that is, during regeneration, overcharging of the battery becomes a problem. However, if too much restriction is applied as in powering, regeneration is insufficient and energy efficiency is reduced.

  The present invention was devised in view of the above problems, and is an AC machine capable of effectively utilizing a battery and powering and regenerating the AC machine with high efficiency within a battery protection range while suppressing hunting. An object is to provide a control device.

In order to achieve the above object, the characteristic configuration of the AC machine control device according to the present invention
When an AC machine functioning as at least one of an AC motor and an AC generator is powered, the power is supplied through the inverter circuit, and when the AC machine is regenerated, the power is received and stored through the inverter circuit. An adjustment torque calculator that adjusts a required torque when the AC machine is controlled by maximum torque control based on a difference between a battery voltage of the battery and a predetermined reference voltage, and calculates an adjustment torque;
When the battery voltage is equal to or lower than a predetermined lower limit voltage when the AC machine is powered and when it is equal to or higher than a predetermined upper limit voltage when the AC machine is regenerated, the target torque of the AC machine is A target torque switching unit that switches between the required torque and the adjustment torque;
It is in the point provided with.

  According to this characteristic configuration, the target torque for controlling the alternator is switched between the adjustment torque obtained by adjusting the required torque based on the difference between the battery voltage and the reference voltage and the original required torque. Even when the battery voltage becomes equal to or lower than a predetermined lower limit voltage during power running, the adjustment torque does not become zero or is uniformly cut and kept at a constant value. The adjustment torque is obtained by adjusting the required torque based on the difference between the battery voltage and a predetermined reference voltage. Therefore, the AC machine can output the maximum torque within the range of power that can be supplied by the battery. it can. Therefore, the battery is effectively used without waste. The same applies during regeneration. Since the adjustment torque is calculated based on the required torque, the target torque smoothly changes when the target torque is switched from the required torque to the adjustment torque or when the adjustment torque is switched from the adjustment torque to the required torque. Therefore, even if the battery voltage fluctuates in the vicinity of a predetermined lower limit during power running, the target torque does not fluctuate greatly, and the AC machine rotates stably without causing hunting. As a result, it is possible to provide an AC machine control device that can effectively use the battery and that can power and regenerate the AC machine with high efficiency within the protection range of the battery by suppressing hunting.

In addition, the adjustment torque calculation unit of the AC machine control device according to the present invention includes:
A required torque storage unit for storing the required torque;
An adjustment amount calculation unit that calculates a torque adjustment amount to be increased or decreased with respect to the required torque by proportional-integral control based on a difference between the predetermined reference voltage and the battery voltage;
It is preferable to include an output unit that calculates the adjustment torque by increasing or decreasing the torque adjustment amount with respect to the request torque stored in the request torque storage unit.

  The request torque is stored in the request torque storage unit, and the adjustment torque is calculated by increasing or decreasing the torque adjustment amount with respect to the stored request torque. Therefore, an appropriate adjustment torque is calculated according to the required torque. Further, since the torque adjustment amount is calculated with high responsiveness by proportional-integral control, the adjustment torque follows the fluctuation of the battery voltage satisfactorily.

Block diagram schematically showing a configuration example of an AC machine control system for controlling an AC machine Block diagram schematically showing a configuration example of an AC machine control device Block diagram schematically showing a configuration example of the target torque setting unit

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram schematically showing the configuration of an AC machine control system that controls an AC machine. Since the AC motor and the AC generator have the same configuration, an AC motor will be described below as an example of the AC machine. An AC machine control system that drives a motor 12 that is an AC motor includes an inverter circuit 5 that is interposed between the motor 12 and a battery 20 that is a DC power source and converts the output of the battery 20 into three-phase AC. Composed. The inverter circuit 5 includes a plurality of switching elements. It is preferable to apply an insulated gate bipolar transistor (IGBT) or a metal oxide semiconductor field effect transistor (MOSFET) to the switching element. Here, the case where IGBT is used as a switching element is illustrated.

  The inverter circuit 5 is configured by a three-phase bridge circuit. Two IGBTs are connected in series between the input plus side 21 and the input minus side 22 of the inverter circuit 5, and this series circuit is connected in parallel in three lines. That is, a bridge circuit in which a set of series circuits corresponds to each of the stator coils u-phase, v-phase, and w-phase of the motor 12 is configured. In FIG. 1, IGBTs Q5, Q1, and Q3 are upper-stage switching elements corresponding to the u-phase, v-phase, and w-phase, respectively. The IGBTs Q6, Q2, and Q4 are lower-stage switching elements corresponding to the u-phase, the v-phase, and the w-phase, respectively. Note that flywheel diodes (regenerative diodes) are connected in parallel to the IGBTs Q1 to Q6, respectively. The flywheel diodes are connected in parallel such that the cathode terminal is connected to the collector terminal of the IGBT and the anode terminal is connected to the emitter terminal of the IGBT.

  The collectors of the IGBTs Q1, Q3, Q5 on the upper side of each phase are connected to the input plus side 21 of the inverter circuit 5, and the emitters are connected to the collectors of the IGBTs Q2, Q4, Q6 on the lower side of each phase. Further, the emitters of the IGBTs Q2, Q4, Q6 on the lower side of each phase are connected to the input minus side 22 (ground) of the inverter circuit 5. The intermediate points (IGBT connection points) of the series circuit by the IGBTs (Q5, Q6), (Q3, Q4), (Q1, Q2) of each phase to be paired are the u-phase, v-phase, and w-phase of the motor 12, respectively. The stator coils 12u, 12v, and 12w are connected to the stator coils 12u, 12v, and 12w, respectively.

  The gates of the IGBTs Q1 to Q6 are connected to an ECU 50 as a control unit via a driver circuit 51, and are individually controlled for switching. The ECU 50 is configured with a logic circuit such as a microcomputer as a core. The ECU 50 corresponds to the motor control device of the present invention. The drive signal input to the gate of the IGBT or MOSFET that switches the high voltage requires a voltage higher than the voltage of a general logic circuit, and therefore is input to the inverter circuit 5 via the driver circuit 51.

  The ECU 50 supplies the motor 12 with a three-phase AC drive current by performing PWM control on the IGBTs Q <b> 1 to Q <b> 6 based on the target torque and the rotational speed for the motor 12. Thereby, the motor 12 powers according to the rotation speed and the target torque. The motor 12 as an alternator works as a generator and the inverter circuit 5 receives power from the alternator side in the same manner as during powering. ECU50 converts IGBTQQ1-Q6 into direct current | flow by carrying out PWM control based on the target torque and rotation speed with respect to an AC machine. It is also possible to simply rectify using flywheel diodes connected in parallel to the IGBTs Q1 to Q6. That is, the inverter circuit 5 converts the DC power from the battery 20 into AC and supplies it when the motor 12 which is an AC machine functioning as at least one of an AC motor and an AC generator is powered. When the motor 12 is regenerated, AC power received from the motor 12 functioning as an AC generator is converted to DC and stored in the battery 20.

  Further, the ECU 50 performs feedback control based on the rotation speed and the motor current. As shown in FIG. 1, a current sensor that functions as a current detection unit 13 is provided to measure the drive current supplied to the u-phase, v-phase, and w-phase stator coils 12 u, 12 v, and 12 w of the motor 2. It has been. The detected value by the current sensor is received by the ECU 50 and used for feedback control. In this example, a configuration is shown in which the currents of all three phases are measured, but since the three phases are in an equilibrium state and the sum of instantaneous current values is zero, only the currents of the two phases are measured and the ECU 50 The remaining one-phase current may be obtained by calculation.

  Further, the motor 12 is provided with a rotation detection sensor such as a resolver as the rotation detection unit 11, and detects the rotation angle (mechanical angle) of the rotor of the motor 12. The rotation detection sensor functions as the rotation detection unit 11 alone or in cooperation with the ECU 50. The rotation detection sensor is set according to the number of poles (the number of pole pairs) of the rotor, and can convert the rotation angle of the rotor into an electrical angle θ and output a signal corresponding to the electrical angle θ. The ECU 50 calculates the rotational speed (angular velocity ω) of the motor 12 and the control timing of the IGBTs Q1 to Q6 of the inverter circuit 5 based on the rotational angle and the electrical angle θ.

  Moreover, the voltage detection part 14 which detects the output voltage of the battery 20 is also provided, and ECU50 acquires the detection result of the voltage detection part 14, and controls the motor 12. FIG. That is, the EUC 50 performs control for adjusting the output torque of the motor 12 according to the voltage of the battery 20. If the amount of power supply to the motor 12 increases while the remaining capacity of the battery 20 is small, the battery 20 may be overdischarged. On the other hand, when the motor 12 functions as a generator, that is, during regeneration, overcharging of the battery 20 becomes a problem. The ECU 50 adjusts the torque of the motor 12 according to the voltage of the battery 20 (battery voltage) in order to suppress such overdischarge and overcharge.

  FIG. 2 is a block diagram schematically showing the configuration of the ECU 50 as an AC machine control device. In FIG. 2, components other than the ECU 50 in the AC machine control system are simply simplified as appropriate. As described above, the ECU 50 is configured with a logic circuit such as a microcomputer as a core. Therefore, each function part of ECU50 does not need to be comprised independently, respectively, and it is sufficient if each function is implement | achieved by cooperation with a program and common hardware. The ECU 50 includes a target current setting unit 1, a current PI control unit 2, a 2-phase / 3-phase conversion unit 3, a PWM control unit 4, a 3-phase / 2-phase conversion unit 6, as shown in FIG. The target torque setting unit 7 and the rotation state calculation unit 10 are included.

  As a method of controlling an AC machine, a control method called vector control (field oriented control: FOC) is known. In the vector control, the coil current flowing through the stator coils of the three phases of the AC machine is a vector of the d axis that is the direction of the magnetic field generated by the permanent magnet disposed on the rotor and the q axis that is orthogonal to the d axis. Performs feedback control by converting coordinates to components. This vector control is also adopted in this example.

  The target current setting unit 1 is a functional unit that sets a target current for driving the motor 12. The target current setting unit 1 receives a target torque set based on a required torque required for the motor 12 from a control unit different from the ECU 50, for example, an ECU that controls the entire vehicle, and the target torque and the motor 12. The target current value is calculated based on the rotation state such as the number of rotations. The rotation state of the motor 12 is detected by the rotation angle detector 11 as described above. The target current value is calculated as a two-phase current of a d-axis current and a q-axis current. The target torque is set by a target torque setting unit 7 described later.

  The current PI control unit 2 is a functional unit that performs current control for determining a drive current for driving the motor 12 and determines a drive voltage based on the determined current. The current PI control unit 2 performs current control based on the target current set by the target current setting unit 1 and the motor current detected by the current detection unit 13 and fed back via the three-phase / two-phase conversion unit 6. Implement to determine the drive current. As the current control method, proportional control (P control) or proportional-integral control (PI control) is generally used. In this example, the case where the proportional-integral control method is used is illustrated, but it is of course possible to use the proportional control method. The motor current is detected by the current detector 13 as described above, and these are actually currents flowing through the three-phase stator coils 12v to 12W. On the other hand, the current PI control unit 2 performs current control on a two-phase current of a d-axis current and a q-axis current in a virtual vector space. Therefore, the three-phase current detected by the current detection unit 13 is converted into a two-phase current in the three-phase / two-phase conversion unit 6 and transmitted to the current PI control unit 2. The current PI control unit 2 calculates a voltage equation using the determined drive current and determines a two-phase drive voltage.

  The two-phase / three-phase conversion unit 3 causes the two-phase drive voltage of the d-axis voltage and the q-axis voltage calculated by the current PI control unit 2 to actually flow the drive current through the three-phase stator coils 12v to 12w. It is a function part which converts into the three-phase voltage which is a drive voltage of. The PWM control unit 4 is a functional unit that generates gate drive signals for switching the IGBTs Q1 to Q6 of the inverter circuit 5 so as to generate the three-phase drive voltages determined by the two-phase / three-phase conversion unit 3. is there. The inverter circuit 5 is switching-controlled by the PWM control unit 4, converts the output of the DC power supply 20 into AC, and drives the motor 12.

  The target torque setting unit 7 is a functional unit that sets a target torque based on the voltage of the battery 20 detected by the voltage detection unit 14 and the required torque. FIG. 3 is a block diagram schematically illustrating a configuration example of the target torque setting unit 7. The target torque setting unit 7 includes an adjustment torque calculation unit 8 and a target torque switching unit 9. The adjustment torque calculation unit 8 includes a request torque storage unit 83, an adjustment amount calculation unit 80, and an output unit 86.

  The target torque switching unit 9 switches the target torque of the motor 12 between a required torque when the motor 12 is controlled by the maximum torque control, which is a standard control, and an adjustment torque in which the required torque is adjusted. It is a functional part. The target torque switching unit 9 includes a changeover switch 91 and a switch control unit 92 that controls the changeover switch 91. The required torque and the adjustment torque are switched by a changeover switch 91. The switch control unit 92 switches the changeover switch 91 based on the voltage VB (battery voltage) of the battery 20 detected by the voltage detection unit 14.

  Specifically, when the motor 12 (alternator) is in a power running operation, the switch control unit 92 switches so that the target torque becomes the adjustment torque when the voltage VB of the battery 20 is equal to or lower than a predetermined lower limit voltage. The switch 91 is controlled. In addition, when the motor 12 (alternator) is in a regenerative operation, the switch control unit 92 sets the changeover switch 91 so that the target torque becomes the adjustment torque when the voltage VB of the battery 20 is equal to or higher than a predetermined upper limit voltage. Control. The target torque switching unit 9 is not necessarily configured using a physical switch such as an analog switch or a relay circuit. The target torque switching unit 9 is also a function unit, and of course may be configured by cooperation of a microcomputer and a program.

  As shown below, the adjustment torque is generated by adding the torque adjustment amount ΔT calculated by the adjustment amount calculation unit to the required torque. Here, the torque adjustment amount ΔT can take both positive and negative values. That is, when the motor 12 is in a power running operation, the amount of power drawn from the battery 20 is suppressed by setting the target torque to be smaller than the required torque. Accordingly, the torque adjustment amount is a negative value. The reverse is true when the motor 12 is in regenerative operation.

  The torque adjustment amount ΔT is calculated by the adjustment amount calculation unit 80. The adjustment amount calculation unit 80 calculates the torque adjustment amount ΔT based on the difference e between the voltage VB of the battery 20 detected by the voltage detection unit 14 and the predetermined reference voltage VR set by the reference voltage setting unit 84. To do. This predetermined reference voltage is set corresponding to each of the reference voltage VRL when the motor 12 is in a power running operation and the reference voltage VRH when the regenerative operation is performed. Further, it is preferable that these predetermined reference voltages have the same value as a predetermined upper limit voltage and a predetermined lower limit voltage, which are threshold values when the changeover switch 91 is controlled. That is, when the motor 12 is in a power running operation, the reference voltage VRL (VR) is equal to a predetermined lower limit voltage. When the motor 12 is in a regenerative operation, the reference voltage VRH (VR) is equal to a predetermined upper limit voltage. It is preferable.

  The difference e is calculated by the differentiator 85. The adjustment amount calculation unit 80 includes a torque PI control unit 81 and an integration unit 82. For example, the torque PI control unit 81 performs proportional-integral control (PI control) on the difference e according to the following equation (1) to calculate an adjustment value δT that is the basis of the torque adjustment amount ΔT. In equation (1), kp and ki are proportional constants, and n indicates the number of repetitive operations (nth).

δT = kp · (e (n) −e (n−1) + ki · e (n) (1)

  The integration unit 82 integrates the adjustment value δT calculated by the torque PI control unit 81 based on the formula (1) to obtain the torque adjustment amount ΔT. The adjustment torque is calculated by adding the required torque temporarily stored in the required torque storage unit 83 and the torque adjustment amount ΔT obtained by the adjustment amount calculation unit 80 in the adder 86. For example, when it is necessary to reduce the discharge amount of the battery 20 by reducing the output torque during the power running operation, the torque adjustment amount ΔT becomes a negative value. Therefore, the adder 86 calculates the torque adjustment amount ΔT from the required torque. Will be subtracted. When the adjustment torque is calculated, it is output to the target torque switching unit 9. The adder 86 corresponds to the output unit of the present invention. As described above, when the changeover switch 91 is switched to the side that outputs the adjustment torque in the switch control unit 92, the adjustment torque is output as the target torque to the target current setting unit 1.

  The adjustment amount calculation unit 80 calculates the torque adjustment amount ΔT based on the difference e between the reference voltage and the battery 20. The target torque is calculated by increasing or decreasing the torque adjustment amount ΔT to the required torque. That is, when the motor 12 is powering, even if the voltage VB of the battery 20 is equal to or lower than the predetermined lower limit voltage, the target torque does not become zero, or is uniformly reduced and does not become a constant value. The target torque is set so that the motor 12 outputs the maximum torque within the range of power that can be supplied by the battery 20. Therefore, the battery 20 can be used effectively.

  Further, when the motor 12 is powering, when the voltage VB of the battery 20 becomes equal to or lower than a predetermined lower limit voltage, the target torque is switched from the required torque to the adjustment torque, but the voltage VB of the battery 20 at the time of switching is the lower limit voltage. It is the neighborhood. Since the reference voltage VRL (VR) is preferably set equal to the lower limit voltage, the difference e calculated by the differentiator 85 is very small. Therefore, the torque adjustment amount ΔT calculated using this difference e is also small, and the difference from the required torque is also small. As a result, the amount of change in the target torque before and after the switching in the target torque switching unit 9 becomes small, so that a smooth transition is achieved. Thereafter, when the voltage VB of the battery 20 is below the lower limit voltage, the adjustment torque (target torque) is set following the voltage VB of the battery 20. Accordingly, the target torque follows well, and the motor 12 rotates stably without causing hunting. The same applies when the voltage VB of the battery 20 recovers and exceeds the lower limit voltage. Since the fluctuation amount of the target torque before and after the switching becomes small, a smooth transition is achieved.

  In the above description, the case where the motor 12 performs a power running operation has been described as an example. Therefore, according to the present invention, the battery 20 can be used effectively, and hunting can be suppressed and the motor 12 (alternator) can be powered and regenerated with high efficiency within the protection range of the battery 20. It is possible to provide a simple AC machine control device.

5: Inverter circuit 8: Adjustment torque calculation unit 9: Target torque switching unit 12: Motor (alternator)
20: Battery 80: Adjustment amount calculation unit 83: Request torque storage unit 86: Adder (output unit)
e: difference between battery voltage and predetermined reference voltage VB: battery voltage VR, VRH, VRL: predetermined reference voltage ΔT: torque adjustment amount

Claims (2)

When an AC machine functioning as at least one of an AC motor and an AC generator is powered, the power is supplied through the inverter circuit, and when the AC machine is regenerated, the power is received and stored through the inverter circuit. An adjustment torque calculator that adjusts a required torque when the AC machine is controlled by maximum torque control based on a difference between a battery voltage of the battery and a predetermined reference voltage, and calculates an adjustment torque;
When the battery voltage is equal to or lower than a predetermined lower limit voltage when the AC machine is powered and when it is equal to or higher than a predetermined upper limit voltage when the AC machine is regenerated, the target torque of the AC machine is A target torque switching unit that switches between the required torque and the adjustment torque;
An AC machine control device comprising: The adjustment torque calculator is
A required torque storage unit for storing the required torque;
An adjustment amount calculation unit that calculates a torque adjustment amount to be increased or decreased with respect to the required torque by proportional-integral control based on a difference between the predetermined reference voltage and the battery voltage;
The AC machine control device according to claim 1, further comprising: an output unit that calculates the adjustment torque by increasing or decreasing the torque adjustment amount with respect to the request torque stored in the request torque storage unit.

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