JP5067604B2 - Electric vehicle control device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance a voltage stabilization effect of a power source line of a system which generates a system voltage on the power source line by boosting a voltage of a DC power source using a step-up converter, and drives an AC motor by the system voltage via an inverter. <P>SOLUTION: The input power (reactive power) of an AC motor 14 is operated to control for stabilizing a system voltage. Here, when the rotational speed of the AC motor 14 is higher than a specified value or when a torque command value is larger than a specified value, a current vector is operated on a delay side to surely obtain a required input power operation amount. Meanwhile, when the rotational speed of the AC motor 14 is a specified value or lower while the torque command value is a specified value or smaller, the current vector is operated on an advancement side to reduce torque fluctuation. When the torque command value of the AC motor 14 is substantially 0, the current vector is strengthed to be set on the magnetic field side, thus preventing the irreversible demagnetization of a permanent magnet. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a control device for an electric vehicle equipped with a system in which a voltage of a DC power source is converted by a conversion means to generate a system voltage and an AC motor is driven by the system voltage via an inverter.

  In an electric vehicle equipped with an AC motor as a power source for a vehicle, for example, as described in Patent Document 1 (Japanese Patent Application Laid-Open No. 2004-274945), an AC motor for driving a drive wheel of a vehicle and an internal combustion engine are disclosed. An AC motor driven by an engine to generate electric power, and a DC voltage obtained by boosting a voltage of a DC power source (secondary battery) by a boost converter is generated in the power line, and each power line is connected to each of the power lines via an inverter. An AC motor is connected and the DC voltage boosted by the boost converter is converted to AC voltage by an inverter to drive the AC motor, or the AC voltage generated by the AC motor is converted to DC voltage by the inverter and this DC voltage is converted. Some are stepped down by a step-up converter and collected by a battery.

In such a system, in order to stabilize the voltage of the power supply line, the voltage of the power supply line is controlled to the target voltage by the boost converter, and the voltage of the power supply line is smoothed by the smoothing capacitor connected to the power supply line. There is something that was made.
JP 2004-274945 A

  However, when the relationship between the driving power of one AC motor and the generated power of the other AC motor (power balance of the two AC motors) changes greatly due to changes in the driving state of the vehicle, etc., the voltage of the power line generated by the change The fluctuation may not be absorbed by the boost converter or the smoothing capacitor, the voltage of the power supply line becomes excessive, and the overvoltage may be applied to the electronic device connected to the power supply line. As a countermeasure, there is a method to increase the voltage stabilization effect of the power supply line by increasing the performance of the boost converter and increasing the capacity of the smoothing capacitor. However, this method increases the size and cost of the boost converter and smoothing capacitor. As a result, there is a problem that it is impossible to satisfy the demands for downsizing and cost reduction of the system.

  In Patent Document 1, when the DC power supply fails, the inverter is set so that the total energy (power balance) of the two AC motors is set to “0” when the DC power supply and the boost converter are interrupted by a relay. Although a control technique is disclosed, this technique is a countermeasure against a failure of a DC power supply, and cannot increase the voltage stabilization effect of the power supply line when the DC power supply is normal. Further, even if it is attempted to control the inverter so that the sum of the energy of the two AC motors is set to “0” during normal operation, one AC motor is connected to the drive shaft of the vehicle and the other AC motor is connected to the internal combustion engine. When connected to the output shaft (that is, when two AC motors are connected to elements with different behaviors), or when the vehicle driving state changes, the influence of the inverter control calculation delay increases. In this case, it is extremely difficult to control the sum of the energy of the two AC motors to be “0”. Furthermore, the AC motor connected to the internal combustion engine cannot avoid the power fluctuation caused by the torque fluctuation of the internal combustion engine, which makes it more difficult to control the sum of the energy of the two AC motors to “0”.

  The present invention has been made in consideration of these circumstances. Therefore, the object of the present invention is to enhance the voltage stabilization effect of the power supply line while satisfying the demands for system miniaturization and cost reduction. It is to provide a control device for an electric vehicle.

In order to achieve the above object, the invention according to claim 1 converts the voltage of a DC power supply to generate a system voltage in the power supply line, the inverter connected to the power supply line, and the inverter driven by the inverter In a control device for an electric vehicle including at least one motor drive unit (hereinafter referred to as “MG unit”) composed of an AC motor, the power required for generating torque of the AC motor of the MG unit by the system voltage control means System voltage stabilization control that suppresses fluctuations in system voltage by operating different input power is executed, and when the torque command value of the AC motor is 0, the AC motor is energized during the system voltage stabilization control. set current or voltage strong field 磁側, further, the set by the target voltage setting means a target value of the system voltage, system The voltage is detected by the voltage detection means, the input power operation amount of the MG unit is calculated based on the target value of the system voltage and the detected system voltage, and the system voltage is controlled based on the input power operation amount. Is.

  In this configuration, the system voltage stabilization control is executed by the system voltage control means so that the input power of the MG unit (AC motor) can be manipulated to suppress fluctuations in the system voltage. Even when the power balance of the AC motor is greatly changed due to the change in the system voltage, the system voltage (voltage of the power supply line) can be stabilized effectively. In addition, the voltage stabilizing effect of the power supply line can be enhanced without increasing the performance of the conversion means and increasing the capacity of the smoothing means, and the requirements for downsizing and cost reduction of the system can be satisfied. In addition, during system voltage stabilization control, the system voltage is controlled by operating input power (that is, reactive power) that is different from the power required for generating torque of the AC motor, so that the torque of the AC motor is substantially constant (for example, The system voltage can be controlled by operating the input power of the AC motor while maintaining the torque command value), and fluctuations in the system voltage can be suppressed without adversely affecting the driving state of the vehicle.

  By the way, when the generated torque of the AC motor is almost zero during the system voltage stabilization control, the current vector is controlled on the d-axis of the dq coordinate system set as the rotation coordinate of the rotor of the AC motor. The reactive power will be operated. However, in this case, as shown by the broken line in FIG. 4, when the current vector is set to the field weakening side and a negative d-axis current is passed, the d-axis armature reaction reverses polarity so that the permanent magnet is demagnetized. Therefore, the permanent magnet may be irreversibly demagnetized. When the permanent magnet is irreversibly demagnetized, the characteristics of the AC motor change, so that the control accuracy of the control using the AC motor (system voltage stabilization control, torque control, etc.) may be reduced.

As a countermeasure against this, the present invention is configured to increase the current or voltage applied to the AC motor to the field-enhancing side when the torque command value at which the generated torque of the AC motor is substantially 0 is 0 during the system voltage stabilization control. I am trying to set it. In this way, when the torque command value at which the generated torque of the AC motor becomes almost zero is 0 (that is, when the reactive power is operated by controlling the current vector or voltage vector on the d axis), Control by using an AC motor can prevent the irreversible demagnetization of the permanent magnet and change the characteristics of the AC motor by setting the voltage vector to the strong field side and flowing a positive d-axis current. It is possible to prevent a decrease in control accuracy due to irreversible demagnetization of the permanent magnet (system voltage stabilization control, torque control, etc.).

Further, the specific control method of the system voltage stabilization control is to set the target value of the system voltage by the target voltage setting means and to detect the system voltage by the voltage detection means as in claim 1 , and calculating an input power operation quantity of MG unit based on the system voltage detected with a target value, as a result good control the system voltage based on the input power operation quantity. In this way, the input power of the MG unit can be manipulated so as to reduce the deviation between the target value of the system voltage and the detected value of the system voltage, and fluctuations in the system voltage can be reliably suppressed.

In this case, as in claim 2 , a first low-pass means for passing a component having a predetermined frequency or less in the system voltage detected by the voltage detection means is provided, and the first low-pass means is passed. The input power manipulated variable of the MG unit may be calculated using a system voltage equal to or lower than the predetermined frequency. In this way, when calculating the input power manipulated variable of the MG unit, the system voltage obtained by removing the noise component (high frequency component) included in the detected value of the system voltage by the first low-pass means is used. It is possible to improve the calculation accuracy of the input power manipulated variable of the MG unit.

  By the way, when system voltage stabilization control is performed to suppress fluctuations in system voltage by manipulating the input power of the MG unit, the control of the system voltage by the input power operation of the MG unit and the control of the system voltage by the conversion means are mutually performed. There is a possibility of interference.

As a countermeasure, the conversion power control means may control the input power or output power (hereinafter referred to as “conversion power”) of the conversion means as in claim 3 . Specifically, as in claim 4 , the converted power command value is calculated by the converted power command value calculating means, the converted power is detected by the converted power detecting means, and the converted power command value and the detected converted power are detected. Based on the above, the control amount of the conversion power may be calculated, and the conversion power may be controlled based on the control amount of the conversion power. In this way, even if the conversion power (input power or output power of the conversion means) fluctuates due to the influence of the system voltage stabilization control (system voltage control by the input power operation of the MG unit), the command value of the conversion power The conversion power can be controlled so as to reduce the deviation between the detected conversion power and the detected conversion power, and interference between the control of the system voltage by the input power operation of the MG unit and the control of the system voltage by the conversion means can be prevented. .

Further, the command value of the conversion power, as in claim 5, the electrical equipment of a commercial 100V to the total value of the input power of the input power (e.g., MG units of all the electric loads including the connected MG unit to the power line The command value of the converted power may be calculated based on the power obtained by adding a power load other than the MG unit such as a DCAC converter to be driven. When the input power of the MG unit is manipulated, the total value of the input power of all the electric loads including the MG unit changes. Therefore, the command value of the converted power is based on the total value of the input power of all the electric loads including the MG unit. Is calculated, it is possible to calculate the command value of the converted power that accurately reflects the influence of the input power operation of the MG unit.

In this case, as in claim 6 , second low-pass means for passing a component having a frequency equal to or lower than a predetermined frequency out of input power of all electric loads including the MG unit connected to the power supply line is provided. You may make it calculate the command value of conversion electric power based on the electric power below the predetermined frequency which passed the 2nd low-pass means. In this way, the command value of the conversion power is set based on the power obtained by removing the noise component (high frequency component) included in the total value of the input power of all electric loads including the MG unit by the second low-pass means. Since calculation can be performed with high accuracy and the speed of the conversion means can be prevented by limiting the bandwidth, the performance of the conversion means can be reduced and the conversion means can be downsized, which is advantageous for mounting in a vehicle.

The detection of the conversion power, as in claim 7, the target value or the detected system voltage of the system voltage may be computed the conversion power based on the output current of the detected converter. In this way, the conversion power can be calculated with high accuracy.

In this case, as in claim 8 , there is provided third low-pass means for passing a component having a frequency equal to or lower than a predetermined frequency in the output current of the conversion means detected by the current detection means, and this third low-pass means is provided. You may make it calculate conversion electric power using the output current below the predetermined frequency which passed the means. In this way, when calculating the conversion power, the output current after the noise component (high frequency component) included in the detected value of the output current of the conversion means is removed by the third low-pass means is used. It is possible to improve the calculation accuracy of the conversion power.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
First, a schematic configuration of an electric vehicle drive system will be described with reference to FIG. An engine 12 that is an internal combustion engine, a first AC motor 13, and a second AC motor 14 are mounted, and the engine 12 and the second AC motor 14 serve as a power source for driving the wheels 11. The power of the crankshaft 15 of the engine 12 is divided into two systems by the planetary gear mechanism 16. The planetary gear mechanism 16 includes a sun gear 17 that rotates at the center, a planetary gear 18 that revolves while rotating on the outer periphery of the sun gear 17, and a ring gear 19 that rotates on the outer periphery of the planetary gear 18. The crankshaft 15 of the engine 12 is connected through a carrier that is not connected, the rotary shaft of the second AC motor 14 is connected to the ring gear 19, and the first AC motor 13 mainly used as a generator is connected to the sun gear 17. Are connected.

  A step-up converter 21 (conversion means) is connected to the DC power source 20 composed of a secondary battery or the like. The step-up converter 21 boosts the DC voltage of the DC power source 20 so as to connect a DC between the power line 22 and the earth line 23. The system voltage is generated or the system voltage is stepped down to return power to the DC power supply 20. A smoothing capacitor 24 for smoothing the system voltage and a voltage sensor 25 (voltage detection means) for detecting the system voltage are connected between the power supply line 22 and the earth line 23, and the current sensor 26 (current detection means) is used. A current flowing through the power supply line 22 is detected.

  Further, a voltage-controlled three-phase first inverter 27 and a second inverter 28 are connected between the power supply line 22 and the ground line 23, and the first inverter 27 is connected to the first AC motor 13. While being driven, the second inverter 28 drives the second AC motor 14. The first inverter 27 and the first AC motor 13 constitute a first motor drive unit (hereinafter referred to as “first MG unit”) 29, and the second inverter 28 and the second AC motor 14 A second motor drive unit (hereinafter referred to as “second MG unit”) 30 is configured.

  The main control device 31 is a computer that comprehensively controls the entire vehicle, and includes an accelerator sensor 32 that detects an accelerator operation amount (an accelerator pedal operation amount), a forward drive or reverse drive of a vehicle, a shift such as parking or neutral. Various sensors such as a shift switch 33 that detects an operation, a brake switch 34 that detects a brake operation, a vehicle speed sensor 35 that detects a vehicle speed, and the output signals of the switches are read to detect the driving state of the vehicle. The main control device 31 sends control signals and data signals between an engine control device 36 that controls the operation of the engine 12 and a motor control device 37 that controls the operation of the first and second AC motors 13 and 14. The control devices 36 and 37 control the operation of the engine 12 and the first and second AC motors 13 and 14 according to the driving state of the vehicle.

  Next, control of the first and second AC motors 13 and 14 will be described with reference to FIGS. As shown in FIG. 2, the first and second AC motors 13 and 14 are three-phase permanent magnet type synchronous motors, each having a built-in permanent magnet, and each rotating the rotor to detect the rotational position of the rotor. Position sensors 39 and 40 are mounted. The voltage-controlled three-phase first inverter 27 is connected to the DC voltage (by the boost converter 21) of the power line 22 based on the three-phase voltage command signals UU1, UV1, UW1 output from the motor control device 37. The boosted system voltage is converted into three-phase AC voltages U1, V1, and W1, and the first AC motor 13 is driven. The U-phase current iU1 and the W-phase current iW1 of the first AC motor 13 are detected by current sensors 41 and 42, respectively.

  On the other hand, the voltage-controlled three-phase second inverter 28 converts the DC voltage of the power supply line 22 into the three-phase AC based on the three-phase voltage command signals UU2, UV2, UW2 output from the motor control device 37. The second AC motor 14 is driven by converting to voltages U2, V2, and W2. The U-phase current iU2 and the W-phase current iW2 of the second AC motor 14 are detected by current sensors 43 and 44, respectively.

  The first and second AC motors 13 and 14 function as generators when driven by inverters 27 and 28 with negative torque. For example, when the vehicle decelerates, AC power generated by the second AC motor 14 by the deceleration energy is converted into DC power by the inverter 28 and charged to the DC power source 20. Usually, a part of the power of the engine 12 is transmitted to the first AC motor 13 via the planetary gear 18 and is generated by the first AC motor 13 to extract the power of the engine 12, and the generated power is the second power. The second AC motor 14 functions as an electric motor. Further, in a state where the power of the engine 12 is divided by the planetary gear mechanism 16 and the torque transmitted to the ring gear 19 is larger than the torque required for vehicle travel, the first AC motor 13 functions as an electric motor. In this case, the second AC motor 14 functions as a generator, and the generated power is supplied to the first AC motor 13.

  Further, the motor control device 37 executes torque control for controlling the torque of the first AC motor 13, torque control for controlling the torque of the second AC motor 14, and torque generation of the second AC motor 14. The system voltage stabilization control is performed by operating the input power (hereinafter referred to as “reactive power”) different from the necessary power to suppress the fluctuation of the system voltage. Further, conversion power control is executed to control the output power of boost converter 21 so that the output power of boost converter 21 matches the command value.

  Hereinafter, the torque control of the first AC motor 13, the torque control of the second AC motor 14, the system voltage stabilization control, and the conversion power control executed by the motor control device 37 will be described.

  As shown in FIG. 2, when the motor control device 37 controls the torque of the first AC motor 13, the torque command value T1 * output from the main control device 31 and the U of the first AC motor 13 are controlled. Based on the phase current iU1 and the W-phase current iW1 (output signals of the current sensors 41 and 42) and the rotor rotational position θ1 of the first AC motor 13 (output signal of the rotor rotational position sensor 39), a sinusoidal PWM control method is used. Three-phase voltage command signals UU1, UV1, UW1 are generated as follows.

  First, the rotor rotational position θ1 of the first AC motor 13 (the output signal of the rotor rotational position sensor 39) is input to the first rotational speed calculator 45, and the rotational speed N1 of the first AC motor 13 is calculated. . Thereafter, in the dq coordinate system set as the rotation coordinates of the rotor of the first AC motor 13, the first torque control current is used to independently control the d axis current id1 and the q axis current iq1. Calculation unit 46 maps torque control current vector it1 * (d-axis torque control current idt1 *, q-axis torque control current iqt1 *) according to torque command value T1 * of first AC motor 13 and rotational speed N1. Or it calculates by numerical formula etc.

  Thereafter, in the first current vector control unit 47, the U-phase and W-phase currents iU1 and iW1 (output signals of the current sensors 41 and 42) of the first AC motor 13 and the rotor rotation of the first AC motor 13 are rotated. Based on the position θ1 (output signal of the rotor rotational position sensor 39), a detected current vector i1 (d-axis detected current id1, q-axis detected current iq1) which is a detected value of the motor current actually flowing to the first AC motor 13 is obtained. The d-axis command voltage Vd1 * is calculated by PI control or the like so that the deviation Δid1 between the d-axis torque control current idt1 * and the d-axis detection current id1 becomes small, and the q-axis torque control current iqt1 * and the q-axis The q-axis command voltage Vq1 * is calculated by PI control or the like so that the deviation Δiq1 from the detected current iq1 becomes small. The d-axis command voltage Vd1 * and the q-axis command voltage Vq1 * are converted into three-phase voltage command signals UU1, UV1, UW1, and these three-phase voltage command signals UU1, UV1, UW1 are output to the first inverter 27. To do.

  In this way, torque control for controlling the torque of the first AC motor 13 is executed so as to realize the torque command value T1 * output from the main control device 31.

  On the other hand, when the motor control device 37 controls the torque of the second AC motor 14, the torque command value T2 * output from the main control device 31, the U-phase currents iU2 and W of the second AC motor 14, and the like. Based on the phase current iW2 (output signals of the current sensors 43 and 44) and the rotor rotational position θ2 of the second AC motor 14 (output signal of the rotor rotational position sensor 40), a three-phase voltage command signal is applied in a sinusoidal PWM control system. UU2, UV2 and UW2 are generated.

  At that time, the torque of the second AC motor 14 is substantially reduced by operating the current vector so as to change only the input power (that is, the reactive power) different from the power necessary for generating the torque of the second AC motor 14. The system voltage stabilization control is performed to control the input power of the second MG unit 30 (second AC motor 14) while maintaining constant (torque command value T2 *) to suppress the fluctuation of the system voltage.

  In the system voltage stabilization control of this embodiment, when the rotational speed N2 of the second AC motor 14 is higher than a predetermined value Nref or the torque command value T2 * (information on generated torque) is larger than the predetermined value Tref. In this case, the input power manipulated variable Pm necessary for stabilizing the system voltage can be reliably realized by manipulating the input power by manipulating the current vector in the delay side (minus direction of the d-axis). On the other hand, when the rotational speed N2 of the second AC motor 14 is less than or equal to the predetermined value Nref and the torque command value T2 * is less than or equal to the predetermined value Tref, the current vector is manipulated to the advance side (the positive direction of the d axis). Torque fluctuation is reduced by manipulating input power.

  Further, when the torque command value T2 * of the second AC motor 14 is substantially 0 (that is, when the reactive power is operated by controlling the current vector on the d axis), the current vector is set to the strong field side. Thus, by passing a positive d-axis current, irreversible demagnetization of the permanent magnet of the AC motor 14 is prevented, and the characteristic change of the AC motor 14 is prevented.

  Specifically, first, the rotor rotational position θ2 of the second AC motor 14 (the output signal of the rotor rotational position sensor 40) is input to the second rotational speed calculation unit 48 to rotate the second AC motor 14. Calculate the speed N2. Thereafter, in the dq coordinate system set as the rotation coordinate of the rotor of the second AC motor 14, the second torque control current is used for the current feedback control of the d-axis current id2 and the q-axis current iq2 independently. Calculation unit 49 maps torque control current vector it2 * (d-axis torque control current idt2 *, q-axis torque control current iqt2 *) according to torque command value T2 * of second AC motor 14 and rotation speed N2. Or it calculates by numerical formula etc.

  Further, the system voltage target value calculation unit 50 (target voltage calculation means) calculates the target value Vs * of the system voltage, and the detected value Vs of the system voltage detected by the voltage sensor 25 is used as the first low-pass filter 51 (first The low-pass filter processing for passing only the low-frequency component of the detected value Vs of the system voltage is performed. Thereafter, the deviation unit 52 obtains a deviation ΔVs between the target value Vs * of the system voltage and the detected value Vsf of the system voltage after the low-pass filter processing, and inputs the deviation ΔVs to the PI controller 53 to determine the system voltage. The input power manipulated variable Pm of the second AC motor 14 is calculated by PI control or the like so that the deviation ΔVs between the target value Vs * and the detected value Vsf of the system voltage after the low-pass filter processing becomes small.

  Thereafter, the input power manipulated variable Pm, the torque control current vector it2 * (d-axis torque control current itt2 *, q-axis torque control current iqt2 *) and the torque command value T2 * are input to the command current calculator 54, The power control current vector ip * (d-axis power control current idp *, q-axis power control current iqp *) for changing the reactive power not contributing to the torque generation of the AC motor 14 by the input power manipulated variable Pm is obtained.

  At this time, as shown in FIG. 3, when the rotational speed N2 of the second AC motor 14 is not more than a predetermined value Nref and the torque command value T2 * of the second AC motor 14 is not more than the predetermined value Tref, the process proceeds. Side power control current vector ip * (power control current vector ip * oriented in the positive direction of the d-axis) is obtained. On the other hand, when the rotational speed N2 of the second AC motor 14 is higher than the predetermined value Nref or the torque command value T2 * is larger than the predetermined value Tref, the delay-side power control current vector ip * (d-axis Find the power control current vector ip *) pointing in the negative direction.

Thereafter, the torque control current vector it2 * (d-axis torque control current idt2 *, q-axis torque control current iqt2 *) and the power control current vector ip * (d-axis power control current idp *, q-axis) The command current vector i2 * (d-axis command current id2 *, q-axis command current iq2 *) on the advance side or the lag side is obtained by combining the power control current iqp *).
i2 * (id2 *, iq2 *) = it2 * (idt2 *, iqt2 *) + ip * (idp *, iqp *)

Further, when the torque command value T2 * of the second AC motor 14 is substantially 0 (that is, when the reactive power is operated by controlling the current vector on the d axis), as shown by the solid line in FIG. The power control current vector ip * (idp *, 0) on the strong field side facing the plus direction on the d-axis is obtained. When the torque command value T2 * is almost 0, the torque control current vector it2 * (idt2 *, iqt2 *) is almost 0. Therefore, the power control current vector ip * (idp *, 0) on the strong field side is used as it is. By setting the command current vector i2 * (id2 *, iq2 *), the command current vector i2 * is set to the strong field side.
i2 * (id2 *, iq2 *) = ip * (idp *, 0)

  The calculation of the command current vector i2 * is executed according to the command current vector calculation program shown in FIG. When this program is started, first, in step 101, the rotational speed N2 of the second AC motor 14 is calculated based on the rotor rotational position θ2 of the second AC motor 14 (the output signal of the rotor rotational position sensor 40). After that, the routine proceeds to step 102 where the torque control current vector it2 * (d-axis torque control current itt2 *, q-axis torque control current iqt2 * corresponding to the torque command value T2 * of the second AC motor 14 and the rotational speed N2 is obtained. ) Is calculated by a map or a mathematical expression.

Then, the procedure proceeds to step 103, torque command value T2 * of the second AC motor 14 is equal to or zero, unless a torque command value T2 * is 0, the process proceeds to step 104, the second It is determined whether or not the rotational speed N2 of the AC motor 14 is not more than a predetermined value Nref and the torque command value T2 * of the second AC motor 14 is not more than a predetermined value Tref.

  As a result, if it is determined that the rotational speed N2 of the second AC motor 14 is equal to or less than the predetermined value Nref and the torque command value T2 * of the second AC motor 14 is equal to or less than the predetermined value Tref, the process proceeds to step 105. Referring to the map of the forward d-axis power control current idp *, according to the input power manipulated variable Pm and the torque control current vector it2 * (d-axis torque control current idt2 *, q-axis torque control current iqt2 *) The forward d-axis power control current idp * is calculated. This map of the d-axis power control current idp * on the advancing side is the advancing side where the power control current vector ip * that changes the reactive power of the second AC motor 14 by the input power manipulated variable Pm is directed in the positive direction of the d-axis. The d-axis power control current idp * on the advancing side is set so as to be the power control current vector ip *.

  On the other hand, if it is determined in step 104 that the rotational speed N2 of the second AC motor 14 is higher than the predetermined value Nref, or the torque command value T2 * of the second AC motor 14 is higher than the predetermined value Tref. If it is determined that the value is larger, the process proceeds to step 106, and the input power manipulated variable Pm and the torque control current vector it2 * (d-axis torque control current itt2 * are referred to with reference to the map of the d-axis power control current idp * on the delay side. , Q-axis torque control current iqt2 *), the d-axis power control current idp * on the delay side is calculated. The map of the delay side d-axis power control current idp * shows that the power control current vector ip * for changing the reactive power of the second AC motor 14 by the input power manipulated variable Pm is the delay side where the d-axis negative direction is directed to the negative direction of the d axis. The d-axis power control current idp * on the delay side is set so that the power control current vector ip * of

ここで、φは鎖交磁束、Ｌd はｄ軸インダクタンス、Ｌq はｑ軸インダクタンスであり、それぞれ交流モータ１４の機器定数である。 Thereafter, the process proceeds to step 107, and the advance side or delay side q-axis power control current iqp * is calculated by the following equation using the advance side or delay side d-axis power control current idp *.

Here, φ is the flux linkage, Ld is the d-axis inductance, and Lq is the q-axis inductance, which are device constants of the AC motor 14, respectively.

  By the processing of these steps 105 to 107, the input power (reactive power) of the second AC motor 14 is changed to the input power manipulated variable while the torque of the second AC motor 14 is kept substantially constant (torque command value T2 *). The power control current vector ip * (d-axis power control current idp *, q-axis power control current iqp *) on the advance side or the lag side that is changed by Pm is obtained.

Thereafter, the process proceeds to step 110, where the torque control current vector it2 * (d-axis torque control current idt2 *, q-axis torque control current iqt2 *) and the power control current vector ip * (d-axis power control current) on the advance side or the lag side. idp * and q-axis power control current iqp *) are combined to determine the lead-side or lag-side command current vector i2 * (d-axis command current id2 *, q-axis command current iq2 *).
i2 * (id2 *, iq2 *) = it2 * (idt2 *, iqt2 *) + ip * (idp *, iqp *)

  As a result, when the rotational speed N2 of the second AC motor 14 is equal to or smaller than the predetermined value Nref and the torque command value T2 * is equal to or smaller than the predetermined value Tref, the command current vector i2 is further advanced than the torque control current vector it2 *. By setting *, the input power is manipulated by manipulating the current vector forward. On the other hand, when the rotational speed N2 of the second AC motor 14 is higher than the predetermined value Nref or the torque command value T2 * is larger than the predetermined value Tref, the command current is delayed to the torque control current vector it2 *. By setting the vector i2 *, the input power is manipulated by manipulating the current vector to the lag side.

On the other hand, if it is determined in step 103 that the torque command value T2 * of the second AC motor 14 is 0 , the process proceeds to step 108 where the q-axis power control current iqp * is set to “0”. Thereafter, the process proceeds to step 109, and the d-axis power control current idp * on the strong field side corresponding to the input power manipulated variable Pm is calculated with reference to the map of the d-axis power control current idp * on the strong field side. The map of the d-axis power control current idp * on the strong field side shows that the power control current vector ip * that changes the reactive power of the second AC motor 14 by the input power manipulated variable Pm is directed in the positive direction on the d-axis. The d-axis power control current idp * on the strong field side is set to a positive value so as to be the power control current vector ip * on the strong field side.

Thereafter, the process proceeds to step 110, where the command current vector i2 * is obtained by combining the torque control current vector it2 * and the power control current vector ip *. If the torque command value T2 * is 0 , the torque control current vector Since it2 * (id2 *, iqt2 *) is substantially 0, the power control current vector ip * (idp *, 0) on the strong field side is directly used as the command current vector i2 * (id2 *, iq2 *).
i2 * (id2 *, iq2 *) = ip * (idp *, 0)

As a result, when the torque command value T2 * of the second AC motor 14 is 0, the command current vector i2 * is set to the strong field side, so that the current vector is operated to the strong field side to be positive. The d-axis current of

  After calculating the command current vector i2 * in this manner, as shown in FIG. 2, the second current vector control unit 55 uses the U-phase and W-phase currents iU2 and iW2 ( Output value of the current sensors 43 and 44) and the detected value of the motor current actually flowing to the second AC motor 14 based on the rotor rotational position θ2 of the second AC motor 14 (output signal of the rotor rotational position sensor 40). A certain detection current vector i2 (d-axis detection current id2, q-axis detection current iq2) is calculated, and the d-axis command is controlled by PI control or the like so that the deviation Δid2 between the d-axis command current id2 * and the d-axis detection current id2 becomes small. The voltage Vd2 * is calculated, and the q-axis command voltage Vq2 * is calculated by PI control or the like so that the deviation Δiq2 between the q-axis command current iq2 * and the q-axis detection current iq2 becomes small. Then, the d-axis command voltage Vd2 * and the q-axis command voltage Vq2 * are converted into three-phase voltage command signals UU2, UV2, UW2, and these three-phase voltage command signals UU2, UV2, UW2 are output to the second inverter 28. To do.

  As described above, torque control for controlling the torque of the second AC motor 14 is executed so as to realize the torque command value T2 * output from the main control device 31, and the torque of the second AC motor 14 is also executed. Input to the second MG unit 30 (second AC motor 14) so that the deviation ΔVs between the target value Vs * of the system voltage and the detected value Vsf is reduced while the torque is kept substantially constant (torque command value T2 *). System voltage stabilization control is performed by controlling power (reactive power) to suppress fluctuations in system voltage. In this case, the PI controller 53, the command current calculation unit 54, and the like serve as system voltage control means.

  Further, the motor control device 37 executes conversion power control for controlling the output power of the boost converter 21 so that the deviation ΔPi between the command value Pif * of the output power of the boost converter 21 and the detected value Pi becomes small.

  Specifically, as shown in FIG. 2, when calculating the command value Pif * of the output power of the boost converter 21, first, the torque command value T1 * and the rotational speed N1 of the first AC motor 13 are set to the first value. The first shaft output calculation unit 56 inputs the shaft output PD1 of the first AC motor 13 and calculates the torque command value T1 * and the rotational speed N1 of the first AC motor 13 as the first output loss calculation unit. 57, the output loss PL1 of the first AC motor 13 is calculated, and the adder 58 adds the output loss PL1 to the shaft output PD1 of the first AC motor 13 to input the first AC motor 13. The electric power Pi1 is obtained. At this time, when the first AC motor 13 functions as a generator, the calculation result of the input power Pi1 of the first AC motor 13 becomes a negative value.

  Further, the torque command value T2 * and the rotational speed N2 of the second AC motor 14 are input to the second shaft output calculation unit 59 to calculate the shaft output PD2 of the second AC motor 14, and the second AC The torque command value T2 * and the rotational speed N2 of the motor 14 are input to the second output loss calculation unit 60 to calculate the output loss PL2 of the second AC motor 14, and then the adder 61 uses the second AC motor 14 to calculate the output loss PL2. The output power PL2 is added to the shaft output PD2 and the input power Pi2 of the second AC motor 14 is obtained. At this time, when the second AC motor 14 functions as a generator, the calculation result of the input power Pi2 of the second AC motor 14 becomes a negative value.

  Thereafter, the total power Pi * is obtained by summing the input power Pi1 of the first AC motor 13 and the input power Pi2 of the second AC motor by the adder 62, and the total power Pi * is obtained as the second low-pass filter. 63 (second low-pass means) is input to perform low-pass filter processing to pass only the low-frequency component of the total power Pi *, and the total power Pif * after this low-pass filter processing is output power The command value is Pif *. The adder 62, the second low-pass filter 63, and the like serve as converted power command value calculation means.

  On the other hand, when the detected value Pi of the output power of the boost converter 21 is calculated, the detected value ic of the output current of the boost converter 21 detected by the current sensor 26 is used as a third low-pass filter 64 (third low-pass means). And a low-pass filter process for passing only the low frequency component of the detected value ic of the output current of the boost converter 21 is performed, and the conversion power detection unit 65 (conversion power detection means) performs a system voltage target value Vs. The detected value Pi of the output power is obtained by multiplying * and the detected value icf of the output current of the boost converter 21 after the low-pass filter processing. The detection value Pi of the output power may be obtained by multiplying the detection value Vsf of the system voltage and the detection value iff of the output current.

  Thereafter, the deviation ΔPi between the command value Pif * of the output power of the boost converter 21 and the detected value Pi is obtained by the deviation unit 66, and this deviation ΔPi is input to the PI controller 67 to output the command of the output power of the boost converter 21. The energization duty ratio Dc of the switching element of the boost converter 21 is calculated by PI control or the like so that the deviation ΔPi between the value Pif * and the detected value Pi becomes small. Thereafter, the boost drive signal calculation unit 68 calculates the boost drive signals UCU and UCL based on the energization duty ratio Dc, and outputs the boost drive signals UCU and UCL to the boost converter 21.

  Thus, by executing the conversion power control for controlling the output power of the boost converter 21 so that the deviation ΔPi between the command value Pif * of the output power of the boost converter 21 and the detected value Pi becomes small, the system voltage is stabilized. Control (system voltage control by operation of input power of second MG unit 30) and system voltage control by boost converter 21 are prevented from interfering with each other. In this case, the PI controller 67, the boost drive signal calculation unit 68, and the like serve as conversion power control means.

  In the present embodiment described above, the system is operated by operating the input power of the second MG unit 30 (second AC motor 14) so that the deviation ΔVs between the target value Vs * of the system voltage and the detected value Vsf becomes small. Since the system voltage stabilization control that suppresses fluctuations in the voltage (voltage of the power supply line 22) is executed, even when the power balance of the two AC motors 13 and 14 changes greatly due to a change in the driving state of the vehicle or the like. The system voltage can be stabilized effectively. In addition, the voltage stabilization effect of the power supply line 22 can be enhanced without increasing the performance of the boost converter 21 and increasing the capacity of the smoothing capacitor 24, thereby satisfying the demands for system downsizing and cost reduction. it can.

  In the present embodiment, the second AC motor 14 is controlled by controlling the current vector so that only the reactive power that does not contribute to the torque generation of the second AC motor 14 is changed during the system voltage stabilization control. The system voltage is controlled by controlling the input power of the second MG unit 30 (second AC motor 14) while maintaining the torque of the motor at a substantially constant value (torque command value T2 *). System voltage fluctuations can be suppressed without adversely affecting the state.

  By the way, as shown in FIG. 6, the current limit value when controlling AC motors 13 and 14 can be represented by a current limit circle, and the voltage limit value can be represented by a voltage limit ellipse. The range inside the current limit circle and inside the voltage limit ellipse is the current vector operable range. As the rotational speed of the AC motors 13 and 14 increases, the voltage limit ellipse becomes smaller and the current vector operable range becomes smaller. There is a characteristic that it is narrowed in the negative direction of the d-axis (the direction in which the d-axis current decreases).

  For this reason, during the system voltage stabilization control, when the rotational speed of the second AC motor 14 is increased and the current vector operable range is narrowed in the negative direction of the d-axis, the current vector is advanced ( If it is attempted to operate the input power by operating in the positive direction of the d-axis), there is a possibility that the input power manipulated variable Pm necessary for stabilizing the system voltage cannot be realized within the current vector operable range. Further, when the torque command value T2 * of the second AC motor 14 becomes large and the current vector (torque control current vector it2 *) becomes long, the current vector is manipulated to the advance side (positive direction of the d-axis). If an attempt is made to manipulate the input power, the input power manipulated variable Pm necessary for stabilizing the system voltage may not be realized within the current vector operable range.

  As these countermeasures, in this embodiment, in the system voltage stabilization control, the rotational speed N2 of the second AC motor 14 is higher than the predetermined value Nref or the torque command value T2 * is larger than the predetermined value Tref. In this case, the current vector is delayed by combining the torque control current vector it2 * with the power control current vector ip * on the lag side and setting the command current vector i2 * on the lag side with respect to the torque control current vector it2 *. Side to operate the input power. As a result, when the rotational speed N2 of the second AC motor 14 becomes higher than the predetermined value Nref and the operable range of the current vector is narrowed in the negative direction of the d-axis, or the torque command of the second AC motor 14 When the value T2 * becomes larger than the predetermined value Tref and the current vector (torque control current vector it2 *) becomes longer, the input power can be manipulated by operating the current vector to the lag side. The input power manipulated variable Pm necessary for system voltage stabilization can be realized within the operable range, and the system voltage stabilization function can be sufficiently exhibited.

  On the other hand, when the rotational speed N2 of the second AC motor 14 is equal to or less than the predetermined value Nref and the torque command value T2 * is equal to or less than the predetermined value Tref, the power control current vector ip * on the leading side is advanced to the torque control current vector it2 *. And the command current vector i2 * is set to the advance side of the torque control current vector it2 *, thereby operating the current vector to the advance side and operating the input power. When operating the input power of the second AC motor 14 while keeping the torque of the second AC motor 14 constant, that is, when operating the current vector along a constant torque curve (see FIG. 3), the current vector Since the torque fluctuation tends to be smaller when operated in the forward direction rather than operating in the delayed direction, the rotational speed N2 of the first AC motor 14 is less than the predetermined value Nref and the torque command value T2 * is the predetermined value. By controlling the input power by operating the current vector forward when Tref or less, torque fluctuation is reduced in the low rotation / low torque region (region where the influence of torque variation is large) of the second AC motor 14. can do.

  Further, in the system voltage stabilization control, when the generated torque of the second AC motor 14 is almost zero, the reactive power is operated by controlling the current vector on the d axis. As shown by the broken line in FIG. 5, if the current vector is set to the field weakening side and a negative d-axis current is passed, the permanent magnet of the second AC motor 14 may be irreversibly demagnetized, and the permanent magnet is irreversible. When the demagnetization is performed, the characteristics of the second AC motor 14 change, so that the control accuracy of the control (system voltage stabilization control, torque control, etc.) using the second AC motor 14 may be reduced. .

As a countermeasure, in this embodiment, when the torque command value T2 * of the second AC motor 14 is 0 during the system voltage stabilization control, as shown by the solid line in FIG. By setting ip * on the strong field side and setting the command current vector i2 * on the strong field side, the current vector is strengthened and the positive d-axis current is made to flow. It is possible to prevent irreversible demagnetization of the permanent magnet of the second AC motor 14 to prevent a change in characteristics of the AC motor 14, and control using the second AC motor 14 (system voltage stabilization control and torque control). Etc.) can be prevented from being deteriorated due to irreversible demagnetization of the permanent magnet.

  In the above embodiment, the torque command value T2 * is used as information on the torque generated by the second AC motor 14, but instead of this, based on the operating state of the second AC motor 14, etc. You may make it use the estimated torque estimated. In the above embodiment, the current vector of the second AC motor 14 is manipulated during the system voltage stabilization control. However, the voltage vector of the second AC motor 14 may be manipulated. .

  In this embodiment, since the input power manipulated variable Pm of the second AC motor 14 is calculated using the detected value Vsf of the system voltage after the low-pass filter process, when calculating the input power manipulated variable Pm. Furthermore, the detection value Vsf of the system voltage after the noise component (high frequency component) included in the detection value Vs of the system voltage is removed by the low-pass filter process can be used, and the calculation accuracy of the input power manipulated variable Pm can be improved. Can do.

  Furthermore, in this embodiment, the command value Pif * of the output power of the boost converter 21 is obtained from the total power Pi * obtained by summing the input power Pi1 of the first AC motor 13 and the input power Pi2 of the second AC motor. The detected value Pi of the output power is obtained by multiplying the target value Vs * (or the detected value Vsf) of the system voltage by the detected value icf of the output current of the boost converter 21, and the output power command value Pif * is detected. Since the conversion power control for controlling the output power of the boost converter 21 is executed so that the deviation ΔPi from the value Pi becomes small, the control of the system voltage by the input power operation of the second MG unit 30 and the boost converter 21 are performed. Interference with the control of the system voltage due to can be prevented.

  In this embodiment, the total power Pif * after the low-pass filter processing is performed on the total power Pi * of the input power Pi1 of the first AC motor 13 and the input power Pi2 of the second AC motor 13 is output from the boost converter 21. Since the power command value Pif * is used, the total power Pif * after the noise component (high frequency component) is removed by the low-pass filter processing can be used as the output power command value Pif *. The value Pif * can be set with high accuracy. In addition, since the speed of the boost converter 21 can be prevented by limiting the bandwidth, the required performance of the boost converter 21 can be reduced and the boost converter 21 can be downsized, which is advantageous for mounting in a vehicle.

  Furthermore, in the present embodiment, the output power detection value Pi is calculated using the output current detection value icf of the boost converter 21 after the low-pass filter processing, and therefore when the output power detection value Pi is calculated. The detection value icf of the output current after the noise component (high frequency component) included in the detection value ic of the output current is removed by the low-pass filter processing can be used, and the calculation accuracy of the detection value Pi of the output power is improved. Can do.

  In the above embodiment, the output power of the boost converter 21 is controlled so that the deviation ΔPi between the command value Pif * of the output power of the boost converter 21 and the detected value Pi becomes small during the conversion power control. However, the input power of the boost converter 21 may be controlled so that the deviation between the command value of the input power of the boost converter 21 and the detected value becomes small.

  In the above-described embodiment, the system voltage stabilization control is performed by controlling the input power of the second MG unit 30 (second AC motor 14) to suppress fluctuations in the system voltage. The input power of one MG unit 29 (first AC motor 13) may be controlled to suppress fluctuations in system voltage. Or, although not shown, for example, in a vehicle having an all-wheel drive configuration in which the third MG unit is mounted on the driven wheel, the input power of the third MG unit is controlled to suppress fluctuations in the system voltage. May be.

  In the above embodiment, the present invention is applied to a so-called split type hybrid electric vehicle in which engine power is divided by a planetary gear mechanism. However, the present invention is not limited to this split type hybrid electric vehicle, and other types of parallel electric vehicles are used. The present invention may be applied to type or series type hybrid electric vehicles. Further, in the above embodiment, the present invention is applied to a vehicle using an AC motor and an engine as a power source. However, the present invention may be applied to a vehicle using only an AC motor as a power source. Further, the present invention may be applied to a vehicle equipped with only one MG unit composed of an inverter and an AC motor, or a vehicle equipped with three or more MG units.

It is a schematic block diagram of the drive system of the electric vehicle in one Example of this invention. It is a block diagram which shows the structure of the control system of an AC motor. It is a figure for demonstrating the calculation method of a command electric current vector. It is a figure for demonstrating the setting method of the command electric current vector in case the torque of an AC motor is substantially zero. It is a flowchart which shows the flow of a process of a command electric current vector calculation program. It is a figure for demonstrating the operable range of an electric current vector.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 13,14 ... AC motor, 20 ... DC power supply, 21 ... Boost converter (conversion means), 22 ... Power supply line, 24 ... Smoothing capacitor, 25 ... Voltage sensor (voltage detection means), 26 ... Current sensor (current detection means) 27, 28 ... inverter, 29, 30 ... MG unit, 37 ... motor control device, 49 ... second torque control current calculation unit, 50 ... system voltage target value calculation unit (target voltage calculation means), 51 ... first Low-pass filter (first low-pass means), 53... PI controller (system voltage control means), 54... Command current calculation section (system voltage control means), 55. Totalizer (converted power command value calculating means), 63 ... second low-pass filter (second low-pass means), 64 ... third low-pass filter (third low-pass means), 65 ... conversion Force detection unit (conversion power detection means), 67 ... PI controller (conversion power control means), 68 ... voltage boosting drive signal computation unit (conversion power control means)

Claims (8)

At least one motor drive unit (hereinafter referred to as “MG unit”) comprising conversion means for converting a voltage of a DC power source to generate a system voltage on a power supply line, an inverter connected to the power supply line, and an AC motor driven by the inverter. In a control device of an electric vehicle provided with
Target voltage setting means for setting a target value of the system voltage;
Voltage detecting means for detecting the system voltage;
Wherein a system voltage control means for executing suppressing system voltage stabilization control the fluctuation of the system voltage by operating the different input power from the power required to torque generation of the AC motor MG unit,
In the system voltage stabilization control, the system voltage control means sets the current or voltage to be supplied to the AC motor to a stronger field side when the torque command value of the AC motor is 0, and sets the target The input power manipulated variable of the MG unit is calculated based on the system voltage target value set by the voltage setting means and the system voltage detected by the voltage detecting means, and the system voltage is controlled based on the input power manipulated variable. A control device for an electric vehicle. A first low-pass means for passing a component having a predetermined frequency or less out of the system voltage detected by the voltage detection means;
The system voltage control means according to claim 1, characterized in that computing the input power operation quantity of the MG unit by using a predetermined frequency below the system voltage has passed through the first low-pass means Electric vehicle control device. Control apparatus for an electric vehicle according to claim 1 or 2, characterized in that it comprises a conversion power control means for controlling the input power or output power (hereinafter referred to as "conversion power") of the converting means. Converted power command value calculating means for calculating a command value of the converted power;
Conversion power detection means for detecting the conversion power,
The converted power control means calculates the control amount of the converted power based on the converted power command value calculated by the converted power command value calculating means and the converted power detected by the converted power detection means, and the converted power The control apparatus for an electric vehicle according to claim 3 , wherein the conversion power is controlled based on a control amount of the electric vehicle. The conversion power command value computation means, according to claim 4, characterized in that for calculating the command value of the conversion power based on the input power of all of the electric load including the MG unit connected to said power supply line Electric vehicle control device. A second low-pass means for passing a component having a frequency equal to or lower than a predetermined frequency out of input power of all electric loads including the MG unit connected to the power line;
6. The electric power according to claim 5 , wherein the converted power command value calculating means calculates a command value of the converted power based on power of a predetermined frequency or less that has passed through the second low-pass means. Automotive control device. At least one of target voltage setting means for setting a target value of the system voltage and voltage detection means for detecting the system voltage;
Current detection means for detecting the output current of the conversion means,
The conversion power detection means is configured to convert the conversion voltage based on a system voltage target value set by the target voltage setting means or a system voltage detected by the voltage detection means, and an output current of the conversion means detected by the current detection means. The electric vehicle control device according to any one of claims 4 to 6 , wherein electric power is calculated. A third low-pass means for passing a component having a predetermined frequency or less in the output current of the conversion means detected by the current detection means;
8. The control apparatus for an electric vehicle according to claim 7 , wherein the converted power detection means calculates the converted power using an output current having a frequency equal to or lower than a predetermined frequency that has passed through the third low-pass means. .

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