JP7490310B2 - Motor Control Device - Google Patents

Description

The present invention relates to a motor control device that controls a motor that generates power for running.

For example, in an electric vehicle (EV), a motor is driven by electricity stored in a battery, and the torque of the motor is transmitted to the drive wheels. In controlling the motor, a torque command value is set based on the vehicle speed and accelerator opening, and power is supplied to the motor so that the torque generated by the motor matches the torque according to the torque command value.

Batteries have an upper limit to the amount of power that can be input and output (charged and discharged). If power exceeding this limit continues to be input and output from the battery, not only will it shorten the battery's lifespan, but it may also cause abnormalities such as fire or smoke. For this reason, when driving at high speeds or climbing hills, the torque command value is limited, taking into account the motor shaft output and power consumption by other devices such as the air conditioner, so that the power output from the battery does not exceed the upper limit of the power that can be input and output.

JP 2011-223791 A

The shaft output of the motor can be calculated from the torque and rotation speed of the motor. The ECU (Electronic Control Unit) that controls the motor acquires data on the motor's rotation speed detected by the motor rotation sensor. The motor's shaft output is then calculated using the rotation speed obtained from the rotation speed data.

However, the rotation speed used by the ECU to calculate the shaft output is a value that lags behind the actual value due to the effects of signal transmission and calculation processing. In particular, when a sudden change in the motor's rotation speed occurs due to tire slippage, the discrepancy between the rotation speed used by the ECU to calculate the shaft output and the actual rotation speed of the motor becomes noticeable. If the rotation speed used by the ECU to calculate the shaft output deviates from the actual rotation speed of the motor, the shaft output of the motor will be calculated to be lower than the actual output, the torque command value will not be restricted correctly, and there is a risk that power will be output that exceeds the upper limit of the power that can be input and output from the battery.

The objective of the present invention is to provide a motor control device that can reduce the discrepancy between the rotation speed used to set the limit value and the actual rotation speed of the motor, and can appropriately limit the torque command value.

In order to achieve the above object, the motor control device according to the present invention is a device for controlling the torque of a motor, which is used in a vehicle equipped with a battery having an input/output upper limit power set as an upper limit of the power that can be input and output, and a motor that consumes the power of the battery to generate power for driving, and includes a rotation speed calculation means for calculating the rotation speed of the motor, a limit value setting means for setting a limit value that is an upper limit of the torque command value for torque control using the rotation speed calculated by the rotation speed calculation means so that the power output from the battery does not exceed the input/output upper limit power, and a limiting means for limiting the torque command value with the limit value set by the limit value setting means as an upper limit, and the rotation speed calculation means periodically acquires and stores rotation speed data corresponding to the rotation speed of the motor, and in response to newly acquired rotation speed data, calculates a predicted value of the motor rotation speed as the rotation speed used by the limit value setting means by performing a calculation that reflects the tendency of changes in the rotation speed of the motor using previously acquired rotation speed data.

According to this configuration, the motor consumes power from the battery to generate power for running the vehicle. In torque control of the motor, a torque command value is set, and power is supplied to the motor so that the torque generated by the motor matches the torque according to the torque command value. An upper limit is set for the torque command value so that the power output from the battery does not exceed the upper input/output power limit.

The motor's rotation speed is used to set the limit value. To calculate the rotation speed, rotation speed data is periodically acquired. When new rotation speed data is acquired, a calculation is performed using the past rotation speed data to calculate a predicted motor rotation speed. The calculated predicted motor rotation speed is then used to set the limit value. This makes it possible to reduce the discrepancy between the rotation speed used to set the limit value and the actual motor rotation speed. As a result, the torque command value can be appropriately limited.

The rotation speed calculation means may be configured to determine whether the rotation speed of the motor is increasing based on previously acquired rotation speed data, and if so, to calculate a predicted value of the motor rotation speed, and if not, to calculate the current rotation speed of the motor from newly acquired rotation speed data.

This configuration reduces the load on the rotation speed calculation means.

According to the present invention, it is possible to reduce the difference between the rotation speed used to set the limit value and the actual rotation speed of the motor, and to appropriately limit the torque command value.

1 is a diagram showing a configuration of a main part of a vehicle equipped with an ECU according to an embodiment of the present invention; FIG. 4 is a block diagram showing a configuration for setting a torque command value. FIG. 4 is a diagram showing an example of a change in the rotation speed of a motor generator over time.

The following describes in detail an embodiment of the present invention with reference to the attached drawings.

<Main components of the vehicle>
FIG. 1 is a diagram showing a configuration of a main part of a vehicle 1 equipped with an ECU 7 according to an embodiment of the present invention.

The vehicle 1 is, for example, an electric vehicle (EV) equipped with a motor generator (MG) 2 as a driving source for running. The motor generator 2 is, for example, a permanent magnet synchronous motor (PMSM) that uses a permanent magnet in the rotor.

The vehicle 1 is equipped with a battery (driving battery) 3 and a PCU (Power Control Unit) 4. The battery 3 is a battery pack made up of a combination of multiple secondary batteries, and outputs, for example, a DC voltage. The PCU 4 has an inverter and a microcontroller built in. The inverter has a circuit configuration in which two series circuits of semiconductor switching elements are provided corresponding to each of the U-phase, V-phase, and W-phase of the motor generator 2, and these series circuits are connected in parallel with each other.

During powered operation in which the motor generator 2 functions as an electric motor, the DC power output from the battery 3 is converted to AC power by the inverter of the PCU 4, and the AC power is supplied to the motor generator 2. This causes the motor generator 2 to generate power, which is then transmitted to the left and right drive wheels 5 via a differential gear or the like.

On the other hand, during regenerative operation in which the motor generator 2 functions as a generator, the power from the drive wheels 5 is converted into AC power by the motor generator 2. At this time, the motor generator 2 acts as a resistor in the drive system, and a regenerative braking force due to this resistance acts on the drive wheels 5. The AC power generated by the motor generator 2 is converted into DC power by the inverter of the PCU 4 and charged into the battery 3.

The vehicle 1 is also equipped with an air conditioner (air conditioner) 6 that conditions the interior of the vehicle. The air conditioner 6 has a refrigeration cycle circuit configuration. That is, the air conditioner 6 includes an electric compressor, a condenser, an expansion valve, and an evaporator. In the air conditioner 6, semi-liquid refrigerant compressed by the electric compressor is supplied to the condenser, where it is cooled and liquefied. The refrigerant liquefied in the condenser is sprayed from the expansion valve to the evaporator, where it absorbs heat from the evaporator and vaporizes all at once, thereby cooling the evaporator. The air conditioner 6 also includes an electric fan, and the air blown from the electric fan passes through the cooled evaporator to become cold air, which is then supplied to the vehicle interior.

The vehicle 1 is equipped with an ECU (Electronic Control Unit) 7 that includes a microcomputer. The microcomputer has built-in components such as a CPU, a non-volatile memory such as a flash memory, and a volatile memory such as a DRAM (Dynamic Random Access Memory). Although only one ECU 7 is shown in FIG. 1, the vehicle 1 is equipped with multiple ECUs to control each part. The multiple ECUs including the ECU 7 are connected to enable two-way communication using the CAN (Controller Area Network) communication protocol.

Various sensors necessary for control are connected to the ECU 7. These sensors include, for example, a vehicle speed sensor 8, an accelerator sensor 9, and a motor rotation sensor 10.

The vehicle speed sensor 8, for example, includes a rotor made of a magnetic material that rotates as the vehicle 1 travels, and an electromagnetic pickup that is not in contact with the rotor, and outputs a pulse signal from the electromagnetic pickup each time the rotor rotates a certain angle. The frequency of this pulse signal corresponds to the actual vehicle speed of the vehicle 1. The ECU 7 determines the frequency of the signal input from the vehicle speed sensor 8, and converts the frequency into vehicle speed.

The accelerator sensor 9 outputs a detection signal corresponding to the amount of operation of the accelerator pedal operated by the user (driver) of the vehicle 1. From the detection signal of the accelerator sensor 9, the ECU 7 determines, for example, the ratio of the operation amount to the maximum operation amount of the accelerator pedal, that is, the accelerator opening degree, which is a percentage where 0% is when the accelerator pedal is not depressed and 100% is when the accelerator pedal is fully depressed.

The motor rotation sensor 10 outputs a pulse signal synchronized with the rotation of the motor generator 2. The ECU 7 calculates the rotation speed of the motor generator 2 based on the signal output from the motor rotation sensor 10. The calculation of this rotation speed will be described in detail later.

In addition, the ECU 7 receives information on the current and voltage input/output to/from the battery 3 as the shaft output of the motor generator 2 from the microcomputer built into the PCU 4.

The ECU 7 executes various controls based on values obtained from detection signals from various sensors and information input from the outside. The ECU 7 controls the power running and regenerative operations of the motor generator 2 by controlling the operation of the inverter of the PCU 4. The vehicle 1 also has an automatic air conditioning function, and the ECU 7 controls the operation of the electric compressor and electric fan of the air conditioner 6 based on values obtained from detection signals from various sensors so that the inside air temperature approaches a temperature set by the user. For example, a temperature setting switch that is operated to set the temperature is located on the instrument panel.

When controlling the power running of the motor generator 2, the torque of the motor generator 2 is controlled by the ECU 7 and the PCU 4. That is, the ECU 7 sets a torque command value in the microcomputer of the PCU 4 so that the torque generated by the motor generator 2 matches the torque corresponding to the torque command value, and the microcomputer of the PCU 4 controls the current supplied to the motor generator 2 from the built-in inverter.

<Torque command value setting process>
FIG. 2 is a block diagram showing a configuration for setting a torque command value.

The ECU 7 essentially includes a power consumption calculation unit 11, a limit value setting unit 12, a torque request value setting unit 13, and a torque command value setting unit 14 as functional processing units required for setting the torque command value used in torque control of the motor generator 2. These functional processing units are realized in software by program processing, or by hardware such as a logic circuit, or by a combination of these.

The power consumption calculation unit 11 calculates the current power consumption of the vehicle 1. In addition to the shaft output of the motor generator 2, the power consumption includes, for example, the power consumption of the air conditioner 6, the power consumption of auxiliary equipment such as an electric water pump that circulates cooling water to the PCU 4, and losses in each part of the vehicle 1.

The limit value setting unit 12 sets a limit value, which is an upper limit of the torque command value, based on the upper limit input/output power of the battery 3 and the power consumption calculated by the power consumption calculation unit 11. The battery 3 has an upper limit on the power that can be input/output (charged/discharged), and the upper limit input/output power is set to a rated power that prevents abnormal deterioration of the battery 3 even when continuous input/output from the battery 3 occurs and does not cause abnormalities such as fire or smoke. The limit value setting unit 12, for example, subtracts the current power consumption from the upper limit input/output power of the battery 3, calculates the maximum increase in the torque command value from the value calculated by the subtraction, and adds the calculated maximum value to the current torque command value to set the limit value.

The torque requirement value setting unit 13 sets a torque requirement value according to the vehicle speed and accelerator opening. That is, the non-volatile memory of the ECU 7 stores the characteristics (relationships) of the torque generated by the motor generator 2 relative to the vehicle speed and accelerator opening in the form of a map as a torque requirement value map, and the torque requirement value setting unit 13 sets a torque requirement value according to the vehicle speed and accelerator opening according to the torque requirement value map. The torque requirement value map is created to indicate, for example, the acceleration of the vehicle 1 according to the amount of accelerator pedal operation (accelerator opening) corresponding to the user's acceleration request from the current vehicle speed, so that the user can feel a sense of acceleration according to the acceleration request.

When the torque request value set by the torque request value setting unit 13 is equal to or less than the limit value set by the limit value setting unit 12, the torque command value setting unit 14 sets the torque request value as is as the torque command value. On the other hand, when the torque request value set by the torque request value setting unit 13 exceeds the limit value set by the limit value setting unit 12, the torque command value is set to the limit value instead of the torque request value as is.

<Motor rotation speed calculation>
FIG. 3 is a diagram showing an example of a change in the rotation speed of the motor generator 2 over time.

In the ECU 7, rotation speed data corresponding to the rotation speed of the motor generator 2 (hereinafter simply referred to as "motor rotation speed") is acquired at each predetermined control period. That is, while the motor generator 2 is operating, a pulse signal synchronized with the rotation of the motor generator 2 is output from the motor rotation sensor 10, and in the ECU 7, the frequency (period) of the pulse signal output from the motor rotation sensor 10 is converted into rotation speed data and acquired at each predetermined control period. The rotation speed data is stored in a volatile memory built into the ECU 7.

Each time new rotation speed data is acquired, the ECU 7 reads out from the volatile memory a number of rotation speed data sets previously acquired (hereinafter referred to as "past data") and determines whether the motor rotation speed is on an increasing trend. If the motor rotation speed is on an increasing trend, the increment in the motor rotation speed during the period in which the past data sets were acquired is found from the previously referenced multiple past data sets. The increment is then added to the motor rotation speed calculated from the most recently acquired rotation speed data to calculate a predicted motor rotation speed value. On the other hand, if the motor rotation speed is not on an increasing trend, the motor rotation speed is calculated from the most recently acquired rotation speed data.

The power consumption calculation unit 11 shown in FIG. 2 calculates the shaft output of the motor generator 2 in order to calculate the power consumption. The shaft output of the motor generator 2 can be calculated by multiplying the torque and motor rotation speed of the motor generator 2 by 2π/60 (π: pi). The motor rotation speed calculated by the above-mentioned method is used to calculate this shaft output. The limit value setting unit 12 sets a limit value, which is the upper limit of the torque command value, using the power consumption calculated by the power consumption calculation unit 11. Therefore, the motor rotation speed is used to set the limit value.

<Action and effect>
As described above, the motor rotation speed is used to set the limit value. To calculate the rotation speed, the frequency of the pulse signal output from the motor rotation sensor 10 is converted into the motor rotation speed, and the motor rotation speed obtained by the conversion is binarized and acquired as the rotation speed data. When new rotation speed data is acquired, the past rotation speed data is used to perform a calculation that reflects the tendency of changes in the motor rotation speed, and a predicted value of the motor rotation speed is calculated. Then, the calculated predicted value of the motor rotation speed is used to set the limit value.

As a result, even if the motor rotation speed calculated from the newly acquired rotation speed data lags behind the actual motor rotation speed, a motor rotation speed that has a small deviation from the actual motor rotation speed can be used to set the limit value. As a result, the shaft output can be accurately calculated, and the power consumption can be accurately calculated, and the limit value of the torque command value that is set using the power consumption can be accurately set.

The torque command value can be appropriately set, so that the battery 3 can supply maximum power to the motor generator 2 while preventing the battery 3 from outputting power that exceeds the upper input/output power limit, thereby improving the power performance of the vehicle 1.

Also, from previously acquired rotation speed data, it is determined whether the motor rotation speed is on an increasing trend, and if it is, a predicted value of the motor rotation speed is calculated, and if it is not on an increasing trend, the current motor rotation speed is calculated from newly acquired rotation speed data. This reduces the number of times the predicted value of the motor rotation speed needs to be calculated, thereby reducing the load on the ECU 7.

The rotation speed data is not limited to a value obtained by converting the frequency of the pulse signal output from the motor rotation sensor 10 into the motor rotation speed, but may be, for example, a value obtained from the PCU 4 via CAN communication.

The past data may also include newly acquired rotation speed data. In other words, each time new rotation speed data is acquired, it may be determined whether the motor rotation speed is on an increasing trend based on the past data including the newly acquired rotation speed data.

<Modification>
Although one embodiment of the present invention has been described above, the present invention can be embodied in other forms.

For example, in the above embodiment, the predicted value of the motor rotation speed is calculated when the motor rotation speed is on an increasing trend, but the predicted value of the motor rotation speed may also be calculated when the motor rotation speed is on a decreasing trend. In this case, when the motor rotation speed is on a decreasing trend, the decrement of the motor rotation speed during the period when the past data was acquired is found from multiple past data. The decrement is then added to the motor rotation speed related to the most recently acquired rotation speed data, thereby calculating the predicted value of the motor rotation speed.

In addition to electric vehicles, the technology of the present invention can also be applied to so-called series-type hybrid vehicles (HVs) equipped with a generator motor that generates electricity using engine power and a drive motor that consumes electricity to generate power for running. Furthermore, the technology of the present invention can also be applied to hybrid vehicles of other types, such as series-parallel types, in addition to series types.

In addition, various design modifications can be made to the above-mentioned configuration within the scope of the claims.

1: Vehicle 2: Motor generator (motor)
3: Battery 7: ECU (motor control device, rotation speed calculation means)
12: Limit value setting unit (limit value setting means)
14: Torque command value setting unit (limiting means)

Claims (2)

1. A device for use in a vehicle equipped with a battery having an input/output upper limit power set as an upper limit of input/output possible power, and a motor that consumes power from the battery to generate power for traveling, the device controlling the torque of the motor,
A rotation speed calculation means for calculating a rotation speed of the motor;
a limit value setting means for setting a limit value that is an upper limit of a torque command value of the torque control, using the rotation speed calculated by the rotation speed calculation means, so that the power output from the battery does not exceed the input/output upper limit power;
a limiting means for limiting the torque command value with the limit value set by the limit value setting means as an upper limit,
The motor control device, wherein the rotation speed calculation means periodically acquires and stores rotation speed data corresponding to the rotation speed of the motor, and, in response to newly acquired rotation speed data, judges whether the rotation speed of the motor is on an increasing trend from the previously acquired rotation speed data, and, when the rotation speed is on an increasing trend, calculates an increment in the rotation speed of the motor during the period during which the rotation speed data used for the judgment of whether the rotation speed is on an increasing trend was acquired , and adds the increment to the rotation speed of the motor corresponding to the most recently acquired rotation speed data , thereby calculating a predicted value of the rotation speed of the motor as the rotation speed to be used by the limit value setting means. 1. A device for use in a vehicle equipped with a battery having an input/output upper limit power set as an upper limit of input/output possible power, and a motor that consumes power from the battery to generate power for traveling, the device controlling the torque of the motor,
A rotation speed calculation means for calculating a rotation speed of the motor;
a limit value setting means for setting a limit value that is an upper limit of a torque command value of the torque control, using the rotation speed calculated by the rotation speed calculation means, so that the power output from the battery does not exceed the input/output upper limit power;
a limiting means for limiting the torque command value with the limit value set by the limit value setting means as an upper limit,
the rotation speed calculation means periodically acquires and stores rotation speed data corresponding to the rotation speed of the motor, and, in response to newly acquired rotation speed data, judges whether the rotation speed of the motor is on a decreasing trend from the previously acquired rotation speed data, and, when the rotation speed is on a decreasing trend, calculates a decrement in the rotation speed of the motor during the period during which the rotation speed data used for the judgment of whether the rotation speed is on a decreasing trend was acquired, and adds the decrement to the rotation speed of the motor corresponding to the most recently acquired rotation speed data, thereby calculating a predicted value of the rotation speed of the motor as the rotation speed to be used by the limit value setting means.

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