CN111869090B

CN111869090B - Driving device, driving method, driving program, and electric vehicle

Info

Publication number: CN111869090B
Application number: CN201880091312.4A
Authority: CN
Inventors: 目黑一由希; 井之口雄大
Original assignee: Shindengen Electric Manufacturing Co Ltd
Current assignee: Shindengen Electric Manufacturing Co Ltd
Priority date: 2018-03-28
Filing date: 2018-03-28
Publication date: 2023-11-03
Anticipated expiration: 2038-03-28
Also published as: TW201942466A; CN111869090A; JP6972305B2; JPWO2019186757A1; WO2019186757A1; TWI702338B

Abstract

The electric vehicle control device 1 according to the present invention includes: a signal receiving unit 11 that receives a signal coming at intervals corresponding to the rotational speed of the motor 3; a rotational speed calculation unit 12 that calculates the instantaneous rotational speed of the motor 3 from the signal interval Δt between the sensor signal S1 and the sensor signal S2; and a motor control unit 13 for generating a PWM signal based on the calculated instantaneous rotation speed, wherein when the variation of the instantaneous rotation speed is equal to or greater than a predetermined value, the motor control unit 13 corrects the duty ratio of the PWM signal based on the instantaneous rotation speed so that the output voltage of the current conversion unit 30 is a value corresponding to the instantaneous rotation speed.

Description

Driving device, driving method, driving program, and electric vehicle

Technical Field

The invention relates to a driving device, a driving method, a driving program and an electric vehicle.

Background

Electric vehicles such as electric two-wheeled vehicles (two-wheeled EVs) generally include a motor for driving wheels and a driving device for controlling a control unit of the motor. Since an electric vehicle can obtain a required torque from a low rotational speed range to a high rotational speed range with a Gear (Gear) fixed, electric vehicles not provided with a clutch have been studied in recent years in the industry. In such a clutch-free electric vehicle (Clutchless), the motor thereof directly receives an external force from outside the wheels, which has been blocked by the clutch in the conventional electric vehicle.

Patent document 1 discloses an engine rotational speed control device that controls the rotational speed of an engine and PWM-controls a motor for opening and closing a drive throttle valve (throttle valve). In addition, a PWM duty correction value for correcting the duty of the PWM signal is calculated in accordance with the target engine rotational speed variation.

[ Prior Art literature ]

Japanese patent application laid-open No. 2005-207416

At a stator of an electric vehicle motor, a rotational position sensor for detecting a rotational position of a rotor is provided. The control unit of the drive device receives a rising edge signal or a falling edge signal (hereinafter also referred to as "sensor signal") from the rotational position sensor for each predetermined electrical angle. The control unit grasps the rotation speed of the motor based on the sensor signal, and controls the motor.

In the above-described clutch-free electric vehicle, since an external force corresponding to a road surface state or the like is directly applied to the motor, the rotational speed of the motor instantaneously fluctuates depending on the road surface state. In this way, the output of the inverter cannot follow such a momentary change in the rotational speed, and therefore the output torque of the motor may deviate from the target value. Next, a specific description will be given with reference to fig. 14.

As shown in fig. 14, when the instantaneous rotation speed of the motor decreases, only the voltage Va of the voltages induced by the rotation of the motor (motor induced voltage) instantaneously decreases. On the other hand, during the period in which the motor voltage is reduced, the output of the inverter that supplies ac power to the motor is unchanged. Thus, the voltage difference between the output voltage of the inverter and the motor induced voltage is increased from V0 to Vb (=v0+va). The voltage difference V0 is a value set so that the target torque can be obtained. Once the voltage difference expands, the result is a current supplied to the motor that is greater than the current required to achieve the target torque, thereby causing the motor output torque to be greater than the target torque.

On the other hand, when the rotation speed instantaneously increases, the motor induced voltage instantaneously increases, but the output of the inverter is unchanged, so that as shown in fig. 14, the difference between the output voltage of the inverter and the motor induced voltage decreases from Vb to Vc, as a result of which the current supplied to the motor is smaller than the current required to obtain the target torque, resulting in an excessively small output torque of the motor.

It has been a problem in the industry that the motor cannot be properly controlled due to a deviation between the output torque of the motor and the target torque caused by the momentary variation in the rotational speed of the motor.

In view of the above, an object of the present invention is to provide a drive device, an electric vehicle control method, an electric vehicle control program, and an electric vehicle that can appropriately control a motor even when the motor rotation speed fluctuates instantaneously due to an external force.

Disclosure of Invention

The driving device according to the present invention is characterized by comprising:

a signal receiving unit that receives a plurality of signals output from a rotational position sensor during a period in which a motor that drives a load rotates one revolution, the signals coming at intervals corresponding to a rotational speed of the motor;

a rotational speed calculation unit that calculates an instantaneous rotational speed of the motor from a signal interval between a reception time point of a first signal received immediately before the signal reception unit and a reception time point of a second signal received earlier than the first signal; and

a motor control section that generates a PWM signal in accordance with the instantaneous rotational speed and transmits the PWM signal to an inverter that supplies alternating-current power to the motor to control the motor,

when the amount of change in the instantaneous rotational speed is equal to or greater than a predetermined value, the motor control unit corrects the duty ratio of the PWM signal so that the output voltage of the inverter is a value corresponding to the instantaneous rotational speed.

In the case of the driving device in question,

the motor control unit corrects the duty ratio by linear interpolation using a characteristic line indicating a relationship between the instantaneous rotation speed and the corrected duty ratio.

In the case of the driving device in question,

the linear interpolation is performed each time the instantaneous rotational speed is calculated.

In the case of the driving device in question,

the characteristic straight line is a straight line connecting the first point with the second point,

the first point is a point defined by a lower limit value of a rotation speed range centering on an average rotation speed calculated from a time of one rotation of the motor and a duty ratio corresponding to the lower limit value,

the second point is a point defined by an upper limit value of the rotation speed range and a duty ratio corresponding to the upper limit value.

In the case of the driving device in question,

the rotation speed range is determined in consideration of a fluctuation range of the instantaneous rotation speed of the motor.

In the case of the driving device in question,

the characteristic line is updated each time the average rotational speed is calculated.

In the case of the driving device in question,

the rotation speed calculating unit calculates the signal interval by multiplying the number of counts counted in the monitoring time interval from the time when the second signal is received until the time when the first signal is received by the monitoring time interval.

In the case of the driving device in question,

in the case where the second signal is one received before the first signal, the rotational speed calculation section calculates the instantaneous rotational speed by the following formula:

n＝60000/(ΔT×Np)

in the above formula, n represents the instantaneous rotation speed [ rpm ], Δt represents the signal interval [ mSec ], and Np represents the number of signals received by the signal receiving unit during one rotation of the motor at an electrical angle.

In the case of the driving device in question,

the motor control unit obtains a duty ratio by searching a duty ratio map indicating a relationship among a target torque of the motor, a rotational speed of the motor, and a duty ratio of the PWM signal using the target torque of the motor and the instantaneous rotational speed.

In the case of the driving device in question,

the load is a wheel of an electric vehicle,

when the motor directly drives the wheels, the motor control unit gradually increases the duty ratio of the PWM signal when the electric vehicle starts.

In the case of the driving device in question,

the signal received by the signal receiving portion is a rising edge signal or a falling edge signal of a pulse signal output from a rotational position sensor provided at the motor.

An electric vehicle according to the present invention includes:

the load described above is a driving device for a wheel of an electric vehicle.

In the electric vehicle in question,

the wheel is mechanically connected to the motor without a clutch.

The driving method according to the present invention includes:

a step in which a signal receiving unit receives a plurality of signals output from a rotational position sensor during a period in which a motor driving a load rotates one revolution, the signals coming at intervals corresponding to the rotational speed of the motor;

a step of calculating an instantaneous rotational speed of the motor by a rotational speed calculation unit based on a signal interval between a reception time point of a first signal received by the signal reception unit and a reception time point of a second signal received earlier than the first signal; and

a step in which a motor control unit generates a PWM signal in accordance with the instantaneous rotational speed and transmits the PWM signal to an inverter for supplying AC power to the motor to control the motor,

The present invention relates to a driver program for causing a computer to execute: a step in which a signal receiving unit receives a plurality of signals output from a rotational position sensor during a period in which a motor driving a load rotates one revolution, the signals coming at intervals corresponding to the rotational speed of the motor; a step of calculating an instantaneous rotational speed of the motor by a rotational speed calculation unit based on a signal interval between a reception time point of a first signal received by the signal reception unit and a reception time point of a second signal received earlier than the first signal; and a motor control unit that generates a PWM signal according to the instantaneous rotational speed and transmits the PWM signal to an inverter that supplies ac power to the motor, thereby controlling the motor, characterized in that:

when the amount of change in the instantaneous rotational speed is equal to or greater than a predetermined value, the motor control unit corrects the duty ratio of the PWM signal based on the instantaneous rotational speed so that the output voltage of the inverter has a value corresponding to the instantaneous rotational speed.

Effects of the invention

In the present invention, the signal receiving unit receives a plurality of signals output from the rotational position sensor during a period of one rotation of the motor, the signals coming at intervals corresponding to the rotational speed of the motor; a rotational speed calculation unit that calculates an instantaneous rotational speed of the motor from a signal interval between the first signal and the second signal; when the calculated change amount of the instantaneous rotation speed is equal to or greater than a predetermined value, the motor control unit corrects the duty ratio of the PWM signal according to the instantaneous rotation speed. The duty ratio is corrected so that the output voltage of the power conversion unit is a value corresponding to the instantaneous rotational speed. In this way, even when the motor rotational speed instantaneously fluctuates due to an external force corresponding to the road surface state or the like being applied to the motor, fluctuation of the motor output torque can be suppressed, and the motor can be appropriately controlled.

Drawings

Fig. 1 is a schematic configuration diagram of an electric vehicle 100 according to an embodiment of the present invention.

Fig. 2 is a schematic configuration diagram of the power conversion unit 30 and the motor 3.

Fig. 3 is a schematic view of a magnet and an angle sensor 4 provided on a rotor 3r of the motor 3.

Fig. 4 is a schematic diagram of the relationship between the rotor angle and the output of the angle sensor.

Fig. 5 is a timing chart for explaining PWM control according to the embodiment.

Fig. 6 is a block diagram of the functions of the control unit 10 of the electric vehicle control device 1.

Fig. 7 is an explanatory diagram for explaining a relation between a sensor signal and the count number, and the like.

Fig. 8 is a schematic diagram for explaining the calculation process of the duty ratio and the output angle of the PWM signal.

Fig. 9 (a) shows the configuration of the torque diagram, fig. 9 (b) shows the configuration of the duty ratio diagram, and fig. 9 (c) shows the configuration of the output angle diagram.

Fig. 10 is a schematic diagram for explaining a temporal change in the output voltage of the inverter according to the present embodiment.

Fig. 11 is a schematic diagram for explaining transient correction of the duty ratio by linear interpolation.

Fig. 12 is a flowchart illustrating an example of an electric vehicle control method according to the embodiment.

Fig. 13 is a graph showing time variation of the duty ratio at the time of direct driving.

Fig. 14 is a schematic diagram for explaining a problem in the conventional art.

Detailed Description

Embodiments according to the present invention will be described below with reference to the drawings. Here, an electric vehicle control device that drives and controls an electric vehicle will be described as one embodiment of the following driving device. The driving device according to the present invention may drive a load other than the wheels of the electric vehicle.

First, an electric vehicle 100 according to an embodiment will be described with reference to fig. 1.

The electric vehicle 100 travels by driving a motor using electric power supplied from a battery. In the present embodiment, the electric vehicle 100 is an electric motorcycle such as an electric motorcycle, specifically, an electric motorcycle in which the motor 3 and the wheels 8 are mechanically connected directly without a clutch as shown in fig. 1. The electric vehicle according to the present invention may be a vehicle in which the motor 3 and the wheels 8 are connected via a clutch. The present invention is not limited to two-wheeled vehicles, and may be, for example, three-wheeled or four-wheeled electric vehicles.

As shown in fig. 1, the electric vehicle 100 includes: an electric vehicle control device 1, a battery 2, a motor 3, an angle sensor (rotational position sensor) 4, an accelerator position sensor 5, an auxiliary switch 6, an instrument (display portion) 7, wheels 8, and a charger 9.

Next, each constituent element of electric vehicle 100 will be described in detail.

The electric vehicle control device 1 is a device that controls an electric vehicle 100, and has: a control unit 10, a memory unit 20, and a power conversion unit (drive) 30. The electric vehicle control device 1 may be configured to control the entire electric vehicle 100 as ECU (Electronic Control Unit).

The following describes each constituent element of the electric vehicle control device 1 in detail.

The control unit 10 inputs information from various devices connected to the electric vehicle control device 1. Specifically, the control unit 10 receives: various signals output from the battery 2, the angle sensor (rotational position sensor) 4, the accelerator position sensor 5, the auxiliary switch 6, and the charger 9. The control unit 10 outputs a signal displayed on the instrument 7. The control unit 10 controls the motor 3 via the power conversion unit 30. Details of the control unit 10 will be described later.

The memory unit 20 memorizes: information (various maps and the like described later) used by the control unit 10 and a program for operating the control unit 10. The memory unit 20 may be, for example, a nonvolatile semiconductor memory, or may not be limited thereto. The memory unit 20 may be incorporated as a part of the control unit 10.

The power conversion unit 30 converts dc power output from the battery 2 into ac power and supplies the ac power to the motor 3. In the present embodiment, the power conversion unit 30 includes an inverter configured by a three-phase full-bridge circuit, as shown in fig. 2. The semiconductor switches Q1, Q3, Q5 are high-side switches, and the semiconductor switches Q2, Q4, Q6 are low-side switches. The control terminals of the semiconductor switches Q1 to Q6 are electrically connected to the control unit 10. The semiconductor switches Q1 to Q6 are, for example, MOSFETs, IGBTs, or the like.

As shown in fig. 2, a smoothing capacitor C is provided between the power supply terminal 30a and the power supply terminal 30 b.

The input terminal 3a is a U-phase input terminal of the motor 3, the input terminal 3b is a V-phase input terminal of the motor 3, and the input terminal 3c is a W-phase input terminal of the motor 3.

As shown in fig. 2, the semiconductor switch Q1 is connected between a power supply terminal 30a to which the positive electrode of the battery 2 is connected and an input terminal 3a of the motor 3. Similarly, the semiconductor switch Q3 is connected between the power supply terminal 30a and the input terminal 3b of the motor 3. The semiconductor switch Q5 is connected between the power supply terminal 30a and the input terminal 3c of the motor 3.

The semiconductor switch Q2 is connected between the input terminal 3a of the motor 3 and the power supply terminal 30b to which the negative electrode of the battery 2 is connected. Similarly, the semiconductor switch Q4 is connected between the input terminal 3b of the motor 3 and the power supply terminal 30 b. The semiconductor switch Q6 is connected between the input terminal 3c of the motor 3 and the power supply terminal 30 b.

The battery 2 supplies electric power to a motor 3 for rotating wheels 8 of the electric vehicle 100. The battery 2 supplies dc power to the power conversion unit 30. The battery 2 may be, for example, a lithium ion battery, or may be another type of battery. The number of the batteries 2 is not limited to one, and may be plural. That is, the electric vehicle 100 may be provided with a plurality of batteries 2 connected in parallel or in series. The battery 2 may include a lead battery for supplying an operation voltage to the control unit 10.

The battery 2 includes a Battery Management Unit (BMU). The battery management unit transmits battery information related to the voltage and state (charging rate, etc.) of the battery 2 to the control section 10.

The motor 3 drives a load such as the wheel 8 by ac power supplied from the power conversion unit 30. In the present embodiment, the motor 3 is mechanically connected to the wheel 8, thereby rotating the wheel 8 in a desired direction. The motor 3 is a three-phase alternating current motor having a U-phase, a V-phase, and a W-phase. As described, the motor 3 and the wheel 8 are directly mechanically connected without via a clutch. In the present embodiment, a three-phase brushless motor is used as the three-phase ac motor, but the type of motor 3 is not limited thereto.

The angle sensor 4 is used to detect the rotational position of the rotor 3r of the motor 3. As shown in fig. 3, magnets (sensor magnets) of N and S poles are alternately mounted on the outer peripheral surface of the rotor 3 r. The angle sensor 4 is constituted by, for example, a hall element, and detects a change in magnetic field accompanying rotation of the motor 3. The number of magnets shown in fig. 3 is merely an example, and is not limited thereto. The magnet may be provided inside a flywheel (not shown).

As shown in fig. 3, the angle sensor 4 includes: a U-phase angle sensor 4U mounted corresponding to U of the motor 3, a V-phase angle sensor 4V mounted corresponding to V of the motor 3, and a W-phase angle sensor 4W mounted corresponding to W of the motor 3. Angle sensors 4u, 4v, and 4w for the respective phases are provided on the motor 3. In the present embodiment, the U-phase angle sensor 4U and the V-phase angle sensor 4V are disposed at an angle of 30 ° with respect to the rotor 3 r. Similarly, the V-phase angle sensor 4V and the W-phase angle sensor 4W are disposed at an angle of 30 ° with respect to the rotor 3r of the motor 3.

As shown in fig. 4, the U-phase angle sensor 4U, the V-phase angle sensor 4V, and the W-phase angle sensor 4W output phase pulse signals corresponding to the rotational position of the rotor 3 r. The width of the pulse signal (or the time interval of the sensor signal) becomes narrower as the rotational speed of the motor 3 (i.e., the wheel 8) becomes higher.

As shown in fig. 4, a number (motor stage number) indicating a motor stage is assigned for each predetermined rotational position. The motor stage indicates the rotational position of the rotor 3r, and in the present embodiment, motor stage numbers 1, 2, 3, 4, 5, 6 are assigned every 60 ° of electrical angle.

The output stage is also called a power-on stage, which is: the motor level detected by the angle sensor 4 is added with a time based on the output angle. The output angle varies according to the rotational speed of the motor 3 and the target torque as will be described later.

The control unit 10 uses the PWM signal to control ON/OFF of the semiconductor switches Q1 to Q6 of the power conversion unit 30. By this, the direct-current power supplied from the battery 2 is converted into alternating-current power. In the present embodiment, as shown in fig. 5, the U-phase low-side switch (semiconductor switch Q2) is PWM-controlled in the output stages 6, 1, 2, 3. The V-phase low-side switch (semiconductor switch Q4) is PWM-controlled in the output stages 2, 3, 4, 5, and the W-phase low-side switch (semiconductor switch Q6) is PWM-controlled in the output stages 4, 5, 6, 1. The stage for performing PWM control is determined by a power-on method or the like, and is not limited to this example.

As described above, by performing ON/OFF control of the low-side switch instead of the high-side switch, it is possible to prevent the current generated by the regenerative operation of the motor 3 from flowing into the battery 2. When the regenerative current is allowed to flow into the battery 2, the high-side switch may be turned ON or OFF.

As shown in fig. 5, the high-side switch also has a time point when it is turned ON. For example, the semiconductor switch Q1, which is a U-phase high-side switch, is ON-controlled at predetermined time intervals in the output stages 1, 2. By thus performing ON control of the high-side switch, heat generation by the power conversion unit 30 can be suppressed. Wherein, to prevent a current short circuit, when the high side switch is controlled to be ON, the corresponding (i.e., same arm) low side switch is controlled to be OFF.

The accelerator position sensor 5 detects an operation amount of an accelerator (hereinafter referred to as "accelerator operation amount") with respect to the electric vehicle 100, and transmits the detected operation amount as an electric signal to the control unit 10. The accelerator operation amount corresponds to the throttle opening of the engine vehicle. The accelerator operation amount increases when the user wants to accelerate, and the accelerator operation amount decreases when the user wants to decelerate.

The assist switch 6 is a switch that a user operates when requesting assistance of the electric vehicle 100. When operated by the user, the assist switch 6 transmits an assist request signal to the control unit 10. The control unit 10 controls the motor 3 to generate assist torque.

The instrument (display portion) 7 is a display (e.g., a liquid crystal panel) provided on the electric vehicle 100, and displays various information. The instrument 7 is provided on, for example, a steering wheel (not shown) of the electric vehicle 100. The instrument 7 shows: information such as the running speed of the electric vehicle 100, the remaining amount of the battery 2, the current time, the total distance travelled, and the remaining distance travelled. The remaining travel distance indicates how much distance the electric vehicle 100 can travel after.

The charger 9 has: a power plug (not shown), and a converter circuit (not shown) for converting ac power supplied through the power plug into dc power. The battery 2 is charged with the dc power converted by the converter circuit. The charger 9 is communicably connected to the electric vehicle control device 1 through a communication network (CAN or the like) in the electric vehicle 100, for example.

The control unit 10 of the electric vehicle control device 1 will be described in detail later.

As shown in fig. 6, the control unit 10 includes: a signal receiving unit 11, a rotational speed calculating unit 12, and a motor control unit 13. The processing in each section of the control section 10 can be realized by software (program).

The signal receiving unit 11 receives a signal coming at an interval corresponding to the rotational speed of the motor 3. The signals are outputted from the angle sensor 4 in plural during one rotation of the motor 3. Specifically, the signal receiving unit 11 receives: sensor signals (i.e., rising edge signals or falling edge signals of pulse signals) output from the U-phase angle sensor 4U, the V-phase angle sensor 4V, and the W-phase angle sensor 4W. In the present embodiment, the signal receiving unit 11 receives the sensor signal every time the rotor 3r of the motor 3 rotates by 60 ° at the electrical angle. Therefore, the signal receiving unit 11 receives six sensor signals during one rotation of the motor 3 at the electrical angle. The time interval at which the sensor signal comes becomes shorter as the rotational speed of the motor 3 becomes higher.

As shown in fig. 7, the signal receiving unit 11 confirms whether or not the sensor signal is received from the angle sensor 4 at each monitoring time interval Δtm. The monitoring time interval Δtm is, for example, a control time interval of the motor 3. Here, the sensor signal may be received by interrupt processing from the angle sensor 4.

When the electric vehicle 100 runs at the highest speed, the monitoring time interval Δtm is shorter than the time interval of the sensor signal received by the signal receiving portion 11, for example, 50 microseconds. In general, when the rotational speed of the motor 3 is maximum, the monitoring time interval Δtm is shorter than the time interval of the sensor signal received by the signal receiving portion 11.

The rotational speed calculation unit 12 calculates the instantaneous rotational speed of the motor 3 from the signal interval (also referred to as the time between sensors). The signal interval here is a time interval between a reception time point of the first signal just received by the signal receiving section 11 and a reception time point of the second signal received earlier than the first signal. In the present embodiment, the second signal is a signal received before the first signal, but the present invention is not limited thereto, and the second signal may be two or more signals received before the first signal.

As shown in fig. 7 in the present embodiment, the signal interval Δt is a time interval between a reception time point of the sensor signal S1 immediately received by the signal receiving unit 11 and a reception time point of the sensor signal S2 received before the sensor signal S1. In this case, the rotational speed calculation section 12 calculates the instantaneous rotational speed of the motor 3 by the formula (1).

n＝60000/(ΔT×Np)…(1)

In the above formula, n represents the instantaneous rotational speed of the motor 3 [ rpm ], Δt represents the signal interval [ mSec ], and Np represents the number of sensor signals received by the signal receiving unit 11 during one rotation of the motor 3 at the electrical angle.

In the present embodiment, the rotational speed calculation unit 12 uses the count number counted at the monitoring time interval Δtm as the signal interval Δt. In the case where the signal receiving section 11 does not receive the sensor signal, the signal receiving section 11 or the rotational speed calculating section 12 will increase the count number by the monitoring time interval Δtm. The count number indicates the time elapsed since the receipt of the just-received sensor signal. The initial value of the count number is 0. Upon receiving the sensor signal, the signal receiving section 11 resets the count number N (i.e., returns to the initial value).

The rotation speed calculating unit 12 calculates the signal interval Δt by multiplying the counted number N of counts by the monitoring time interval Δtm in a period from the time when the sensor signal S1 is received until the time when the sensor signal S2 is received.

In the case of measuring the signal interval using the count number, the rotational speed calculation section 12 calculates the instantaneous rotational speed of the motor 3 by the formula (2).

n＝60000/(NΔtm×Np)…(2)

In the above formula, N represents the instantaneous rotational speed [ rpm ] of the motor 3, N represents the number of counts counted from the time when the sensor signal S2 is received until the time when the sensor signal S1 is received, Δtm represents the monitoring time interval [ mSec ], and Np represents the number of sensor signals received by the signal receiving unit 11 during one rotation of the motor 3 at the electrical angle.

The motor control unit 13 generates a PWM signal for generating a required torque for the motor 3 based on the instantaneous rotational speed calculated by the rotational speed calculation unit 12. The motor control unit 13 sends the generated PWM signal to the power conversion unit 30 to control the motor 3.

In the present embodiment, the motor control unit 13 calculates the duty ratio and the output angle (energization time point) from the instantaneous rotational speed and the target torque, and outputs the PWM signal having the calculated duty ratio to the power conversion unit 30 at the calculated output angle. By so doing, the motor 3 is controlled to generate the target torque. Although the PWM signal is generated at the monitoring time interval, it may be generated every time the sensor signal is received, or every time the motor 3 rotates one revolution.

The calculation of the duty ratio and the output angle will be described in detail with reference to fig. 8 and 9. The motor control unit 13 is configured to: the rotational speed in the torque map M1 is searched for using the accelerator operation amount received from the accelerator position sensor 5 and the instantaneous rotational speed calculated via the rotational speed calculation unit 12, thereby obtaining the target torque. Here, the torque diagram M1 is shown in fig. 9 (a), and is shown as follows: a relationship among the accelerator operation amount, the rotational speed of the motor 3, and the target torque of the motor 3.

Next, the motor control unit 13 controls: the duty ratio map M2 is searched using the target torque acquired from the torque map M1 and the instantaneous rotational speed calculated via the rotational speed calculation section 12, thereby acquiring the duty ratio. Here, the duty ratio diagram M2 is shown in (b) of fig. 9, and is shown as follows: relation among the target torque of the motor 3, the rotational speed of the motor 3, and the duty ratio of the PWM signal.

The motor control section 13 further: the output angle map M3 is searched using the target torque acquired from the torque map M1 and the instantaneous rotational speed calculated via the rotational speed calculation section 12, thereby acquiring an output angle. Here, the output angle diagram M3 is shown in fig. 9 (c), which shows: a relation among a target torque of the motor 3, a rotational speed of the motor 3, and an output angle of the PWM signal.

When the control unit 10 controls the power conversion unit 30 using a plurality of energization modes (for example, 120 ° energization mode and 180 ° energization mode), the duty ratio map M2 and the output angle map M3 corresponding to the respective energization modes are used. That is, when the 120 ° conduction mode is used, the duty ratio and the output angle are obtained using the duty ratio map and the output angle map for the 120 ° conduction mode, and when the 180 ° conduction mode is used, the duty ratio and the output angle are obtained using the duty ratio map and the output angle map for the 180 ° conduction mode.

The PWM signal having the duty ratio obtained as described above is output to the power conversion section 30 at the output angle obtained as described above, and the semiconductor switches Q1 to Q6 are controlled ON/OFF. By doing so, the motor 3 is controlled to generate a desired torque.

Next, the transient correction of the duty ratio by the motor control unit 13 will be described in detail with reference to fig. 10 and 11.

When the amount of change in the instantaneous rotational speed calculated by the rotational speed calculation unit 12 is equal to or greater than a predetermined value, the motor control unit 13 corrects the duty ratio of the PWM signal based on the instantaneous rotational speed. Although details will be described later, the duty ratio is corrected as follows: the output voltage of the inverter (power conversion unit 30) is set to a value corresponding to the instantaneous rotational speed. That is, the duty cycle is corrected as: the output voltage of the inverter is set to a value corresponding to the motor induced voltage.

In the example shown in fig. 10, until time t1, the difference between the output voltage of the inverter and the motor induced voltage (voltage induced by the rotation of the motor 3) (hereinafter, referred to as "voltage difference" alone) is V0. Subsequently, the instantaneous rotational speed is instantaneously decreased from time t1, and the amount of decrease in the instantaneous rotational speed reaches a prescribed value Δn1 in time t 2. As the instantaneous rotational speed decreases, the voltage difference between the motor-induced voltage and the voltage at the motor-induced voltage increases temporarily from time t1 to time t2, as shown in fig. 10.

However, when the amount of decrease in the instantaneous rotational speed reaches the predetermined value Δn1, the motor control unit 13 corrects the duty ratio of the PWM signal based on the instantaneous rotational speed. By driving the inverter using the corrected PWM signal having the duty ratio, as shown in fig. 10, the voltage difference is reduced (in a steady state, the voltage difference is V1) due to a decrease in the output voltage of the inverter. Since the expansion of the voltage difference is suppressed by instantaneously correcting the duty ratio in this way, the current integrated with the target torque can flow through the motor 3, and the output torque can be suppressed from becoming excessively large.

The same applies when the instantaneous rotational speed increases. In the example shown in fig. 10, the voltage difference until time t3 is V1. Subsequently, the instantaneous rotational speed is instantaneously increased from time t3, and the amount of increase in the instantaneous rotational speed reaches a prescribed value Δn2 in time t 4. As the instantaneous rotational speed increases, the motor induced voltage also increases, and as a result, the voltage difference temporarily decreases from time t3 to time t 4.

However, once the amount of increase in the instantaneous rotational speed reaches the predetermined value Δn2, the motor control unit 13 corrects the duty ratio of the PWM signal according to the instantaneous rotational speed. As shown in fig. 10, the inverter is driven by using the corrected PWM signal with the duty ratio, and the voltage difference increases (in a steady state, the voltage difference is V2) as the output voltage of the inverter increases. In this way, the current integrated with the target torque can flow through the motor 3, and the output torque can be suppressed from becoming too small.

In the present embodiment, the predetermined value Δn1 and the predetermined value Δn2 are determined according to the amount of change in the count number. For example, in fig. 7, when the number of counts counted between the sensor signal S1 and the sensor signal S2 is greater (or less) than the predetermined value than the number of counts counted between the sensor signal S2 and the sensor signal S3, the instantaneous correction of the duty ratio is performed.

Next, a method of instantaneously correcting the duty ratio by linear interpolation will be described with reference to fig. 11. A characteristic line L representing the relationship between the instantaneous rotation speed and the corrected duty ratio is used. The characteristic line L is a line connecting the point a and the point B. Here, the point a is a point defined by a lower limit value X1 of the rotation speed range R centered on the average rotation speed Nav and a duty ratio Y1 of the instantaneous rotation speed corresponding to the lower limit value X1. The average rotation speed Nav is a rotation speed calculated from the time of one rotation of the motor 3. The point B is a point defined by the upper limit value X2 of the rotation speed range R and the duty ratio Y2 of the instantaneous rotation speed corresponding to the upper limit value X2.

The duty ratios Y1, Y2 are obtained from the duty ratio map M2. That is, the duty ratio map M2 is searched for by using the instantaneous rotational speed of the lower limit value X1 and the target torque at that time to obtain the duty ratio Y1, and the duty ratio map M2 is searched for by using the instantaneous rotational speed of the upper limit value X2 and the target torque at that time to obtain the duty ratio Y2.

The following relational expression holds for the rotation speed range R.

X1＝Nav-f…(3)

X2＝Nav+f…(4)

In this formula, f is the fluctuation range of the instantaneous rotational speed of the motor 3.

The fluctuation range f is a maximum value of the instantaneous rotational speed from the average rotational speed Nav due to the road surface condition on which the electric vehicle 100 is traveling, the accuracy of the angle sensor 4, and the like. The fluctuation width f is, for example, 500rpm. By determining the rotation speed range R in consideration of the fluctuation range f of the instantaneous rotation speed of the motor 3 in this way, even when the instantaneous rotation speed greatly fluctuates due to the fluctuation of the road surface state, the accuracy of the angle sensor 4, and the like, linear interpolation can be accurately performed, and the duty ratio can be instantaneously corrected.

The characteristic straight line L is updated every time the average rotational speed is calculated by the rotational speed calculating section 12. That is, the characteristic straight line L is updated by updating the rotation speed range R each time the average rotation speed is calculated, and by obtaining the duty ratios corresponding to the instantaneous rotation speeds of the lower limit value and the upper limit value of the rotation speed range R by using the torque map M1 and the duty ratio map M2, respectively. By doing so, it is possible to perform linear interpolation using the characteristic line L suitable for the running state of the electric vehicle 100, and thus it is possible to accurately maintain instantaneous correction of the duty ratio.

Here, the characteristic line L may be updated against a change in the accelerator operation amount received from the accelerator position sensor 5. Thus, the duty ratio can be corrected with higher accuracy.

In the present embodiment, the characteristic straight line L connecting the point a and the point B is used to perform linear interpolation, and the duty ratio is corrected. That is, as shown in fig. 11, the value of the characteristic line L corresponding to the instantaneous rotation speed Nm calculated by the rotation speed calculation unit 12 is obtained as the corrected duty ratio. Each time the instantaneous rotational speed is calculated by the rotational speed calculation section 12, linear interpolation is performed.

As described above, in the electric vehicle control device 1 according to the present embodiment, the signal receiving unit 11 receives a plurality of sensor signals output from the angle sensor 4 during one rotation of the motor 3, the sensor signals arrive at intervals corresponding to the rotation speed of the motor 3, the rotation speed calculating unit 12 calculates the instantaneous rotation speed of the motor 3 from the signal interval Δt between the sensor signal S1 and the sensor signal S2, and the motor control unit 13 corrects the duty ratio of the PWM signal from the instantaneous rotation speed when the calculated variation of the instantaneous rotation speed is equal to or greater than a predetermined value. The duty ratio is corrected so that the output voltage of the power conversion unit 30 (inverter) is a value corresponding to the instantaneous rotational speed (i.e., motor induced voltage). That is, the duty ratio of the PWM signal is instantaneously corrected in accordance with the instantaneous variation of the rotational speed of the motor 3, so that the voltage difference between the inverter and the motor induced voltage does not deviate from the value based on the target torque. In this way, even when the rotational speed instantaneously fluctuates due to an external force applied to the motor 3 in accordance with the road surface condition, fluctuation of the output torque of the motor 3 can be suppressed, and appropriate motor control can be performed.

Electric vehicle control method

Next, an example of the electric vehicle control method according to the present embodiment will be described with reference to the flowchart of fig. 12. Wherein the count number is initialized in advance.

The signal receiving unit 11 determines whether or not the monitoring time interval Δtm has elapsed (step S11). When the monitoring time interval Δtm has elapsed (Yes in step S11), it is determined whether or not a sensor signal has been received from the angle sensor 4 (step S12). In the case where the sensor signal is not received (S12: no), the count number is increased by one (step S13), and the process returns to step S11.

On the other hand, when the sensor signal is received (Yes in step S12), the rotational speed calculation unit 12 calculates the instantaneous rotational speed of the motor 3 from the number of counts counted between the sensor signal S1 and the sensor signal S2 (step S14). The rotational speed calculation unit 12 resets the count number to an initial value (step S15). The resetting of the count number may be performed at any one of the time points of steps S15 to S19.

Subsequently, the motor control unit 13 obtains the duty ratio and the output angle of the PWM signal from the instantaneous rotation speed calculated in step S14 and the accelerator operation amount received from the accelerator position sensor 5 (step S16). Specifically, as described with reference to fig. 8, the duty ratio and the output angle of the PWM signal are obtained by using the torque map M1, the duty ratio map M2, and the output angle map M3.

Next, the motor control unit 13 determines whether or not the amount of change in the instantaneous rotational speed calculated in step S14 is equal to or greater than a predetermined value (step S17). The judgment in this step is carried out by: for example, it is determined whether or not the number of counts this time (the number of counts between the sensor signal S1 and the sensor signal S2) is larger (or smaller) than the number of counts last time (the number of counts between the sensor signal S2 and the sensor signal S3) by a predetermined value.

When the amount of change in the instantaneous rotational speed is equal to or greater than a predetermined value (S17: yes), the duty ratio obtained in step S16 is corrected (step S18). The correction in this step is performed by, for example, linear interpolation using the characteristic line L. Subsequently, a PWM signal having the corrected duty ratio is transmitted to the inverter to control the motor 3 (step S19).

On the other hand, when the amount of change in the instantaneous rotational speed is smaller than the predetermined value (S17: no), the flow proceeds to step S19 without correcting the duty ratio, and the PWM signal of the duty ratio obtained in step S16 is transmitted to the inverter.

According to the above-described driving method, even when the rotational speed instantaneously fluctuates due to the external force applied to the motor 3 in accordance with the road surface condition, fluctuation of the output torque of the motor 3 can be suppressed, and appropriate motor control can be performed.

Although the above-described processing flow uses the count number, the instantaneous rotational speed may be calculated by calculating the signal interval using the time point of receiving the sensor signal. If the sensor signal is not received (S12: no), the duty ratio may be acquired from the duty ratio map M2 using the operation amount of the accelerator immediately before and the calculated instantaneous rotation speed. The characteristic line L may be updated using the obtained duty ratio to update the PWM signal transmitted to the power conversion unit 30.

In some electric vehicles, the motor 3 drives the wheels 8 directly (i.e., in a direct drive mode), i.e., without a hub damper. The present invention is also applicable to such an electric vehicle. In this case, as shown in fig. 13, the motor control unit 13 desirably gradually increases the duty ratio of the PWM signal when the electric vehicle 100 is started (at a low rotation speed). In this way, even in the case of the direct drive system, the electric vehicle 100 can be smoothly started.

At least a part of the electric vehicle control device 1 (control unit 10) described in the above embodiment may be configured by hardware or software. When the control unit 10 is configured by software, a program for realizing at least a part of the functions of the control unit may be stored in a storage medium such as a floppy disk or a CD-ROM, and a computer may be read and then run. The storage medium is not limited to a removable magnetic disk, an optical disk, or the like, but may be a fixed storage medium such as a hard disk device or a memory.

The program for realizing at least a part of the functions of the control unit 10 may be distributed via a communication line (including wireless communication) such as the internet. The program may be further distributed in a state after encryption, modulation, and compression via a limited line such as the internet, a wireless line, or a storage medium.

Based on the above description, although it is possible for those skilled in the art to think of the additional effect and various modifications of the present invention, the present invention is not limited to the above-described various embodiments. The constituent elements according to the different embodiments may be appropriately combined. Various additions, modifications and partial deletions can be made without departing from the spirit and scope of the concept of the invention as defined in the appended claims and their equivalents.

Symbol description

1. Electric vehicle control device

2. Battery cell

3. Motor with a motor housing

3r rotor

4. Angle sensor

4u U phase angle sensor

4v V phase angle sensor

4w W phase angle sensor

5. Throttle position sensor

6. Auxiliary switch

7. Instrument for measuring and controlling the intensity of light

8. Wheel of vehicle

9. Charger (charger)

10. Control unit

11. Signal receiving part

12. Rotational speed calculation unit

13. Motor control unit

20. Memory part

30. Power conversion unit

100. Electric vehicle

f fluctuation width

L characteristic straight line

M1 torque schematic

M2 duty cycle schematic

M3 output Angle schematic diagram

Nav average rotational speed

Q1, Q2, Q3, Q4, Q5, Q6 semiconductor switches

R rotation speed range

S1, S2, S3 sensor signals

Claims

1. A driving device, characterized by comprising:

a motor control section that generates a PWM signal in accordance with the instantaneous rotational speed and sends the PWM signal to an inverter that supplies alternating-current power to the motor to control the motor,

2. The drive device according to claim 1, wherein:

3. The drive device according to claim 2, wherein:

wherein the linear interpolation is performed each time the instantaneous rotational speed is calculated.

4. The drive device according to claim 2, wherein:

wherein the characteristic straight line is a straight line connecting the first point and the second point,

5. The drive device according to claim 4, wherein:

wherein the rotation speed range is determined in consideration of a fluctuation range of the instantaneous rotation speed of the motor.

6. The drive device according to claim 4, wherein:

wherein the characteristic line is updated each time the average rotational speed is calculated.

7. The drive device according to claim 1, wherein:

8. The drive device according to claim 1, wherein:

wherein, in the case where the second signal is one received before the first signal, the rotational speed calculation section calculates the instantaneous rotational speed by the following formula:

n=60000/(ΔT×Np)

in the above formula, n represents the instantaneous rotational speed rpm, Δt represents the signal interval mSec, np is a value representing the number of signals received by the signal receiving section during one rotation of the motor at an electrical angle.

9. The drive device according to claim 1, wherein:

wherein the motor control unit obtains the duty ratio by searching a duty ratio map indicating a relationship among the target torque of the motor, the rotational speed of the motor, and the duty ratio of the PWM signal using the target torque of the motor and the instantaneous rotational speed.

10. The drive device according to claim 1, wherein:

wherein the load is a wheel of an electric vehicle,

11. The drive device according to claim 1, wherein:

wherein the signal received by the signal receiving portion is a rising edge signal or a falling edge signal of a pulse signal output from a rotational position sensor provided at the motor.

12. An electric vehicle, characterized by comprising:

the driving device according to claim 1, wherein the load is a wheel of an electric vehicle.

13. The electric vehicle of claim 12, characterized in that:

wherein the wheel is mechanically connected to the motor without a clutch.

14. A driving method, characterized by comprising:

15. A computer-readable storage medium having recorded thereon a driver for causing a computer to execute:

a step in which a motor control unit generates a PWM signal according to the instantaneous rotational speed and transmits the PWM signal to an inverter that supplies ac power to the motor, thereby controlling the motor, the motor control unit being characterized by: