JP2022014133A - Electric vehicle - Google Patents

Abstract

To provide an electric vehicle which can appropriately control a motor for traveling.SOLUTION: An electric vehicle 1 comprises: a battery 2; a motor for traveling; a converter 12 that raises a voltage supplied from the battery; an inverter that converts electric power supplied from the converter and supplies the electric power after conversion to the motor; and a control device 40. The control device increases a torque fluctuation of the motor by controlling the inverter during EV traveling by the motor and when an upper arm 11a of the step-up converter is turned on and a lower arm 11b is turned off, calculates an input current Idc to the inverter on the basis of voltages Vu to Vw and currents Iu to Iw of each phase of the motor, and on the basis of the current, calculates a plurality of electric power related values concerning the step-up converter and the electric power of the battery. An internal resistance Rb of the battery is identified in such a manner that the calculated electric power related values and measurement values of the electric power related values measured by a sensor are conformed to each other, and a control constant for controlling the motor is changed according to the internal resistance.SELECTED DRAWING: Figure 2

Description

The present invention relates to an electric vehicle.

A technique relating to an electric vehicle that estimates the internal resistance of a battery based on the current value of a traveling motor, the voltage to an inverter, or the like and controls the torque of the motor based on this internal resistance is known (for example, Patent Documents). 1).

Japanese Unexamined Patent Publication No. 2015-056971

According to the above technology, the resistance value of a single battery can be estimated, but the resistance value of the entire system cannot be calculated in consideration of the resistance component in the circuit. As a result, the motor may not be controlled properly.

An object of the present invention is to provide an electric vehicle capable of appropriately controlling a traveling motor.

The above object is a battery, a traveling motor, a boost converter that boosts the voltage supplied from the battery, and an inverter that converts the power supplied from the boost converter and supplies the converted power to the motor. And a control device, the control device controls the motor by controlling the inverter when the upper arm of the boost converter is on and the lower arm is off during EV traveling by the motor. To increase the torque fluctuation of the motor, calculate the input current to the inverter based on the voltage and current of each phase of the motor, and based on the input current to the inverter, a plurality of power boost converters and batteries. The power-related value was calculated, and the internal resistance of the battery corresponding to the calculated value of the power-related value was identified and identified so that the measured value of the power-related value measured by the sensor and the calculated value match. It can be achieved by an electric vehicle that switches the control constant for controlling the motor according to the internal resistance.

According to the present invention, it is possible to provide an electric vehicle capable of appropriately controlling a traveling motor.

FIG. 1 is a schematic configuration diagram of an electric power system of an electric vehicle. FIG. 2 is a flowchart showing an example of control executed by the ECU. 3A to 3F are explanatory views of torque fluctuation of the motor. FIG. 4A is a graph comparing the measured value and the calculated value of the voltage VL when the torque fluctuation of the motor is increased during the boost control, and FIG. 4B shows the motor while the boost control is stopped. It is a graph comparing the measured value and the calculated value of the voltage VL when the torque fluctuation of is small, and FIG. 4C shows the voltage VL when the torque fluctuation of the motor is increased while the boost control is stopped. It is a graph which compared the measured value and the calculated value. FIG. 5A is a graph comparing the measured value of the voltage VH before switching the control constant with the command value, and FIG. 5B compares the measured value of the current IB before switching the control constant with the command value of the current IL. FIG. 5C is a graph comparing the measured value of the torque of the motor before switching the control constant with the command value. FIG. 6A is a graph comparing the measured value of the voltage VH after switching the control constant with the command value, and FIG. 6B compares the measured value of the current IB after switching the control constant with the command value of the current IL. FIG. 6C is a graph comparing the measured value of the torque of the motor after switching the control constant with the command value.

FIG. 1 is a schematic configuration diagram of the electric power system of the electric vehicle 1. The electric vehicle 1 includes a battery 2, a converter 12, an inverter 13, a traveling motor 20, a generator 30, and an ECU 40. The motor 20 is a three-phase alternating current type, and is driven by electric power supplied from the battery 2 via the converter 12 and the inverter 13 and electric power supplied from the generator 30 via the inverter 13. The generator 30 may be, for example, a motor generator that performs regenerative power generation, or may be a motor generator that generates power by being driven by an internal combustion engine. The battery 2 is, for example, a fuel cell, but is not limited to this, and may be a lithium ion battery, a nickel hydrogen battery, or the like.

The output power of the battery 2 is input to the converter 12. The converter 12 includes a filter capacitor 5, a reactor 6, an upper arm 11a, and a lower arm 11b. The filter capacitor 5 is connected in parallel to the input end of the converter 12. The smoothing capacitor 8 is connected in parallel to the input end of the inverter 13. The upper arm 11a and the lower arm 11b are connected in series. The upper arm 11a and the lower arm 11b each include a switching element and a diode connected in antiparallel to each other. The upper arm 11a and the lower arm 11b are typically IGBTs (Insulated Gate Bipolar Transistors). The converter 12 controls the on period (duty ratio) of the upper arm 11a and the lower arm 11b by using pulse width modulation (PWM) to boost the capacitor voltage VH, which is the voltage between both ends of the smoothing capacitor 8. The step-down operation can be performed. Here, by controlling the upper arm 11a to be on and the lower arm 11b to be turned off, the boosting operation by the converter 12 can be stopped.

The converter 12 includes voltage sensors 4 and 7, and a current sensor 9. The voltage sensor 4 measures the voltage VL, which is the voltage between both ends of the filter capacitor 5. The voltage sensor 7 measures the voltage VH, which is the voltage between both ends of the smoothing capacitor 8. The current sensor 9 measures the current IL flowing through the reactor 6. The measured values of these sensors are output to the ECU 40.

The output end (output end on the high potential side) of the converter 12 is connected to the input end (DC input end) of the inverter 13. The inverter 13 is a device that outputs the three-phase AC of UVW that drives the three-phase AC motor. The motor 20 is provided with sensors for measuring U-phase current Iu, U-phase voltage Vu, V-phase current Iv, V-phase voltage Vv, W-phase current Iw, and W-phase voltage Vw, respectively, and the ECU 40 is equipped with sensors thereof. The measured value is output.

The ECU 40 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory). The ECU 40 controls the switching elements of the upper arm 11a and the lower arm 11b.

Next, the control executed by the ECU 40 will be described. FIG. 2 is a flowchart showing an example of the control executed by the ECU 40. The ECU 40 determines whether or not EV traveling is in progress (step S1). The EV traveling is a state in which the motor 20 is driven by the electric power supplied from the battery 2 without using the electric power supplied from the generator 30. If No in step S1, this control ends.

Next, the ECU 40 determines whether or not the upper arm 11a is on and the lower arm 11b is off (step S2). That is, it is determined whether or not the boosting is stopped by the converter 12. If No in step S2, this control ends.

In the case of Yes in step S2, the ECU 40 controls the inverter 13 to increase the torque fluctuation of the motor 20 (step S3). 3A to 3F are explanatory views of torque fluctuation of the motor 20. 3A to 3C are explanatory views of torque fluctuation of the motor 20 in a normal state. 3D to 3F are explanatory views when increasing the torque fluctuation of the motor 20. In FIGS. 3A, 3B, 3D, and 3E, the U-phase current Iu is shown by a solid line, the V-phase current Iv is shown by a dotted line, and the W-phase current Iw is shown by a dashed line. The phases of the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw are shifted by 120 ° with one cycle as 360 °. In FIGS. 3B and 3E, the case where the current value is negative is inverted to positive. 3C and 3F show the torque of the motor 20. Here, Iu = -Iv-Iw always holds. As shown in FIGS. 3A to 3C, the upper and lower limit values of the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw match so that the torque fluctuation of the motor 20 becomes small in the normal state. Is controlled. On the other hand, as shown in FIGS. 3D to 3F, in step S3, for example, the V-phase current Iv and the W-phase current Iw are offset to the plus side by controlling the inverter 13, whereby the U-phase current Iu is generated. It is offset to the minus side. As a result, the torque fluctuation of the motor 20 increases.

Next, the ECU 40 calculates the DC current Idc input to the inverter 13 based on the following equation (1) (step S4).
Idc = (Iu * Vu + Iv * Vv + Iw * Vw) / VH ... (1)
Here, the ECU 30 may detect the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw by sensors, respectively, but as described above, Iu = -Iv-Iw always holds, so that the U-phase is always established. If it can be detected by at least two sensors of the current Iu, the V-phase current Iv, and the W-phase current Iw, the remaining values can be calculated.

Ｒｍ＝（Ｖｂ－ＩＬ＊Ｒｂ－ＩＬ＊ＲＩ）／ＩＬ・・・（３）
ここで静電容量Ｃｍは、平滑化コンデンサ８の静電容量である。静電容量Ｃｆは、フィルタコンデンサ５の静電容量である。内部インダクタンスＬｂは、バッテリ２の内部インダクタンスである。抵抗成分ＲＩは、リアクトル６の抵抗成分である。インダクタンス成分Ｌは、リアクトル６のインダクタンス成分である。内部抵抗Ｒｂは、バッテリ２の内部抵抗である。静電容量Ｃｍ、静電容量Ｃｆ、内部インダクタンスＬｂ、抵抗成分ＲＩ、及びインダクタンス成分Ｌは、予めＥＣＵ４０のＲＯＭに記憶されているが、内部抵抗Ｒｂは記憶されていない。 Next, the ECU 40 calculates the voltage VH, the voltage VL, the current IL, and the current IB based on the following equations (2) and (3) (step S5). The current IB is the current output by the battery 2. The voltage VH, voltage VL, current IL, and current IB correspond to power-related values for the inverter 13 and the battery 2.

Rm = (Vb-IL * Rb-IL * RI) / IL ... (3)
Here, the capacitance Cm is the capacitance of the smoothing capacitor 8. The capacitance Cf is the capacitance of the filter capacitor 5. The internal inductance Lb is the internal inductance of the battery 2. The resistance component RI is the resistance component of the reactor 6. The inductance component L is the inductance component of the reactor 6. The internal resistance Rb is the internal resistance of the battery 2. The capacitance Cm, the capacitance Cf, the internal inductance Lb, the resistance component RI, and the inductance component L are stored in the ROM of the ECU 40 in advance, but the internal resistance Rb is not stored.

Next, the ECU 40 uses the calculated values of the voltage VH, the voltage VL, the current IL, and the current IB obtained by the above equation, and the voltage VH and the voltage measured by the voltage sensor 7, the voltage sensor 4, and the current sensor 9, respectively. The internal resistance Rb is identified so that it matches the measured values of VL, current IL, and current IB (step S6). As shown by the above equation (2), the resistance component of the circuit of the converter 12 and the like are reflected in this internal resistance Rb.

Next, the ECU 40 switches the control constant according to the identified internal resistance Rb (step S7). The control constant is switched with reference to a predetermined map according to the value of the internal resistance Rb. This map is stored in the ROM of the ECU 40. Here, the control constant is a gain used for feedback control. For example, it is used for feedback control in which the current value for controlling the motor 20 is the control target and the actual current value follows the current command value. As a result, the motor 20 can be controlled with high accuracy.

Further, as described above, the internal resistance Rb is identified during EV traveling (Yes in step S1). Therefore, it is not necessary to consider the influence of the generator 30, and the formula for identifying the internal resistance Rb can be simplified as described above. In addition, the number of voltage sensors and current sensors can be reduced, and the identification system for the internal resistance Rb is improved.

Next, the measured value and the calculated value of the voltage VL will be described. FIG. 4A is a graph comparing the measured value and the calculated value of the voltage VL when the torque fluctuation of the motor 20 is increased during the boost control. The vertical axis shows voltage and the horizontal axis shows time. As shown in FIG. 4A, the difference between the measured value and the calculated value of the voltage VL is large due to the boost control. FIG. 4B is a graph comparing the measured value and the calculated value of the voltage VL when the boost control is stopped and the torque fluctuation of the motor 20 is small. Since the voltage VL does not fluctuate, the amount of fluctuation due to noise or the like included in the measured value is large with respect to the calculated value. FIG. 4C is a graph comparing the measured value and the calculated value of the voltage VL when the boost control is stopped and the torque fluctuation of the motor 20 is increased. As shown in FIG. 4C, the difference between the measured value and the calculated value is small. Therefore, by identifying Rm in such a state as in the case of Yes in steps S1 and S2 described above, the influence of voltage / current fluctuation due to noise or the like is suppressed, and Rm is identified accurately. Can be done.

FIG. 5A is a graph comparing the measured value of the voltage VH before switching the control constant with the command value. FIG. 5B is a graph comparing the measured value of the current IB before switching the control constant with the command value of the current IL. FIG. 5C is a graph comparing the measured value of the torque of the motor 20 and the command value before switching the control constant. FIG. 6A is a graph comparing the measured value of the voltage VH after switching the control constant with the command value. FIG. 6B is a graph comparing the measured value of the current IB after switching the control constant with the command value of the current IL. FIG. 6C is a graph comparing the measured value of the torque of the motor 20 after switching the control constant with the command value. As shown in the figure, the control accuracy of each parameter value is improved after the control constants are switched. In this way, the control accuracy of the motor 20 is improved. As a result, LC resonance, rectangular step-up resonance, and the like can be suppressed.

In the above embodiment, an electric vehicle equipped with a motor has been described as an example, but the present invention is not limited to this, and an electric vehicle equipped with both a motor and an internal combustion engine as a power source for traveling, a so-called hybrid vehicle may be used.

Although the examples of the present invention have been described in detail above, the present invention is not limited to such specific examples, and various modifications and variations are made within the scope of the gist of the present invention described in the claims. It can be changed.

1 Electric vehicle 2 Battery 11a Upper arm 11b Lower arm 12 Converter 13 Inverter 20 Motor 30 Generator 40 ECU (control device)

Claims (1)

With the battery
With a driving motor
A boost converter that boosts the voltage supplied from the battery,
An inverter that converts the power supplied from the boost converter and supplies the converted power to the motor.
Equipped with a control device,
The control device is
When the upper arm of the boost converter is on and the lower arm is off during EV traveling by the motor, the torque fluctuation of the motor is increased by controlling the inverter.
The input current to the inverter is calculated based on the voltage and current of each phase of the motor.
Based on the input current to the inverter, a plurality of power-related values relating to the power of the boost converter and the battery are calculated.
The internal resistance of the battery is identified so that the measured value of the power-related value measured by the sensor corresponding to the calculated value of the power-related value matches the calculated value.
An electric vehicle that switches a control constant for controlling the motor according to the identified internal resistance.

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