JP2004215374A - Controller for vehicle motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller for a vehicle motor capable of preventing a locked state of the motor, and of avoiding continuation of an overheating state of a switching device. <P>SOLUTION: A motor control unit 20 comprises an inverter controller 7 for controlling an inverter 8; and a torque required value calculating section 2 for calculating a torque required value 1 based on a signal of an accelerator opening, and uses rotational speed of the motor 9 and an inverter temperature TI as input signals. A rotational speed command generating part 3 of the motor control part 20 confirm that there is τ1≥τo and ω≤ωo. The motor 9 determines whether or not it is in the locking state or an ultra low rotational speed state. A rotational speed command lower limit value calculating section 12 calculates such a rotational speed ωL that the inverter temperature does not excessively increase. A rotational speed command control processing part 4 selects the larger one of the rotational speed ωL and a predetermined rotational speed ω1, and takes it as a rotational sped command value ω2. A torque command value calculator 5 calculates a torque command value τ2 larger than τ1 based on ω2 to control the inverter 8. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control device for a vehicular motor that converts a DC current into a plurality of phases of AC power by a switching element and is driven by the AC power, and in particular, an overcurrent is applied to a switching element that drives the motor when the motor is locked. The present invention relates to an overload prevention of an electric motor for preventing breakage caused by flowing of electric motor.
[0002]
[Prior art]
[Patent Document 1] Japanese Patent Application Laid-Open No. H11-215687 In an electric vehicle, when the accelerator pedal is insufficiently depressed when climbing a hill, there is a possibility that the driving force due to the motor torque and the retreating force due to gravity may be balanced or the vehicle may run at a very low speed. In that case, the current flowing in one of the three phases of the motor may be up to twice as large as the other phases, and the current concentrates on a specific switching element of the inverter, causing a rapid temperature rise. This switching element may be thermally damaged.
Conventionally, in order to prevent the thermal destruction of the switching element of the inverter during the locked state of the motor or the ultra-low speed rotation, the locked state of the motor is detected based on the temperature rise of the switching element and the rotation speed of the motor, and the output current is limited. Alternatively, it has been considered to shift the rotation angle of the rotor of the electric motor by stopping the output or changing the phase (see Patent Document 1).
[0003]
[Problems to be solved by the invention]
According to this conventional technique, when it is detected that the electric motor is locked, the torque of the electric motor is reduced, the rotation angle of the rotor is shifted, and the phase is changed. By shifting the energization from the switching element to another switching element that is not in an overheated state, a large torque can be generated to escape from the locked state.
[0004]
However, even if the motor starts to be rotated using a switching element that is not in an overheated state, torque is generated again by the switching element that has been in an overheated state, and there is a problem that the overheated state is continued.
SUMMARY OF THE INVENTION It is an object of the present invention to provide a control device for a motor for a vehicle that can prevent a locked state of the motor and avoid a continuation of an overheated state of a switching element in order to solve the above-described problems.
[0005]
[Means for Solving the Problems]
Therefore, the present invention provides an inverter for controlling driving power supplied to an electric motor provided in a vehicle, and a first request for calculating a first torque request value for the electric motor based on a driver's accelerator operation amount. Torque calculation means, rotation number detection means for detecting the rotation number of the motor, and determining that the first required torque value is equal to or greater than a predetermined torque value and that the rotation number of the motor is equal to or less than the predetermined first rotation number. Determining means for calculating a second required torque value based on a predetermined second rotational speed greater than the first rotational speed; and determining that the first required torque value is equal to the predetermined required torque. If the torque value is less than the first torque value or the rotation speed of the motor is greater than the first rotation speed, the inverter is controlled based on the first torque request value, and the first torque request value is equal to or more than the predetermined torque value and The rotation speed is less than or equal to the first rotation speed If it was assumed that an inverter control means for controlling the inverter based on the second torque request value.
[0006]
【The invention's effect】
According to the present invention, the inverter control means determines that the first torque request value corresponding to the accelerator opening calculated by the first required torque calculation means is less than a predetermined torque value or the rotation speed from the rotation speed detection means is at a predetermined rotation speed. If the number of rotations is greater than 1, the inverter is controlled based on the first required torque value, and the first required torque value is equal to or greater than a predetermined torque value and the number of rotations from the rotation speed detecting means is equal to the first predetermined torque value. If the rotation speed is equal to or less than the rotation speed, it is determined that the electric motor may be locked due to insufficient depression of the accelerator, and the second rotation speed is determined based on the predetermined second rotation speed that is higher than the predetermined first rotation speed. Since the inverter is controlled by generating the second required torque value larger than the first required torque value calculated by the required torque calculating means, the occurrence of the locked state of the electric motor can be prevented.
As a result, current concentrates on the one-phase switching element of the inverter, and the possibility of the switching element being thermally damaged is reduced.
[0007]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
FIG. 1 is a diagram showing a block configuration of a control device for a motor for a vehicle.
An accelerator opening detector 1 for detecting the accelerator opening is connected to the motor controller 20, and a control signal corresponding to the accelerator opening signal is output from the motor controller 20 to the inverter 8, and the inverter 8 is connected to the motor controller 20. By controlling the electric power to the electric motor 9 based on the control signal from the controller 9, the drive control of the electric motor 9 is performed.
The inverter 8 is provided with an inverter temperature detector 10 for detecting the temperature (hereinafter referred to as an inverter temperature) TI of a switching element constituting the inverter 8, and a signal of the inverter temperature TI is input to the motor controller 20.
The motor 9 is provided with a motor speed detector 11 for detecting the speed, and a signal of the speed ω is input to the motor controller 20.
The motor control unit 20 is configured by a microcomputer.
[0008]
The configuration of the motor control unit 20 will be described in more detail.
The motor control unit 20 includes a torque request value calculation unit 2, a rotation speed command generation unit 3, a rotation speed command restriction processing unit 4, a torque command value calculation unit 5, a torque command value selection unit 6, an inverter control unit 7, and a rotation speed command. It is composed of a lower limit operation unit 12.
The accelerator opening signal from the accelerator opening detector 1 is input to the required torque value calculator 2. The torque request value calculation unit 2 calculates a torque request value τ1 based on the torque request value and outputs the torque request value τ1 to the rotation speed command generation unit 3 and the torque command value selection unit 6.
The signal of the inverter temperature TI from the inverter temperature detector 10 is input to the rotation speed command lower limit value calculator 12.
The signal of the rotation speed ω of the motor 9 from the motor rotation speed detection unit 11 is input to the rotation speed command generation unit 3, the torque command value calculation unit 5, and the torque command value selection unit 6.
[0009]
The rotation speed command generation unit 3 compares the rotation speed ω input from the motor rotation speed detection unit 11 with the built-in predetermined rotation speed ωo, and compares the torque request value τ1 with the built-in predetermined torque value τo. In comparison, when ω ≦ ωo and τ1 ≧ τo, the torque command value switching flag Lτ = 1 is set, and when ω> ωo or τ1 <τo, the torque command value switching flag Lτ = 0, and the torque command value is set. Output to the selection unit 6.
Further, when the torque command value switching flag Lτ = 1, the rotation speed command generation unit 3 sets a predetermined temporary target rotation speed ω1 incorporated therein as the rotation speed command value, and outputs it to the rotation speed command restriction processing unit 4. I do.
[0010]
The predetermined rotation speed ωo is a rotation speed of approximately 0 rpm, and the predetermined torque value τo is a torque value required when the vehicle starts at a creep speed on a normal flat ground.
The provisional target rotation speed ω1 is a predetermined rotation speed that can prevent overheating of the switching element of the inverter 8, and is, for example, a rotation speed of an electric motor that generates a creep speed when the vehicle starts moving.
[0011]
The rotation speed command restriction processing unit 4 compares the provisional target rotation speed ω1 with the rotation speed command lower limit value ωL output from the rotation speed command lower limit value calculation unit 12 described later, and selects the larger one to rotate. It is set as the number command value ω2 and output to the torque command value calculation unit 5 and the torque command value selection unit 6.
The torque command value calculation unit 5 calculates a torque command value τ2 necessary for increasing the number of revolutions of the electric motor in an uphill state by, for example, PI calculation from the deviation between the revolution number instruction value ω2 and the current number of revolutions ω of the electric motor 9. Are output to the torque command value selector 6 and the rotational speed command lower limit calculator 12.
[0012]
Based on the torque command value τ2 output from the torque command value calculation unit 5 and the inverter temperature TI output from the inverter temperature detection unit 10, the rotation speed command lower limit value calculation unit 12 controls the motor 9 in which the switching element of the inverter 8 does not overheat. The minimum rotation speed is calculated and output to the rotation speed command restriction processing unit 4 as the rotation speed command lower limit value ωL.
[0013]
When the torque command value switching flag Lτ = 0, the torque command value selection unit 6 performs the torque request value τ1 from the torque request value calculation unit 2 as the torque command value τc output to the inverter control unit 7 as normal torque control. And the torque request value τ1 from the torque command value τ2 from the torque command value calculation unit 5.
[0014]
When the torque command value switching flag Lτ = 1 and ω <ω2, the torque command value selection unit 6 performs torque control as torque command value τc as torque control to prevent the inverter temperature from excessively rising due to the locked state of the motor. τ2 is selected and output to the inverter control unit 7.
When the torque command value switching flag Lτ = 1 and the relationship between the rotation speed ω of the electric motor 9 and the rotation speed command value ω2 is ω ≧ ω2, it is determined that the torque control for preventing the inverter temperature from excessively rising has been completed, and the torque command value switching flag is determined. Lτ is reset to 0, and a torque request value τ1 is selected as a torque command value τc to be output to the inverter control unit 7.
Inverter control section 7 outputs a signal for controlling the switching element of inverter 8 to inverter 8 based on the input torque command value τc.
[0015]
In the rotation speed command lower limit value calculation unit 12, the rotation speed command lower limit value ωL is obtained from the torque command value τ2 and the inverter temperature TI as follows.
In the case of a three-phase current value and a waveform having a large peak current value, to prevent the inverter temperature TI from excessively rising, the allowable time during which the current can continuously flow through the switching elements for one phase is short. It is necessary to shorten the cycle (that is, increase the rotation speed of the electric motor 9).
When the peak current value is low, the heat generation amount of the switching element is small, so that the energization cycle can be lengthened. That is, a low rotation speed of the electric motor 9 can be allowed.
[0016]
Since the peak value of the current flowing through the switching element can be predicted from the torque command value output to the inverter control unit 7, the degree to which the inverter temperature TI increases within a predetermined time after receiving the torque command value τ2 can be predicted. If the current inverter temperature TI, which is the base temperature, is known, the minimum number of revolutions necessary for the inverter temperature TI not to exceed a predetermined value due to heat generation due to energization can be determined.
Therefore, the relationship between the minimum rotational speed of the electric motor 9 at which the inverter temperature TI does not become equal to or more than the predetermined value, using the torque command value and the inverter temperature TI as parameters, is determined in advance by experiments or the like. By having the data in the form of a map such as a lookup system, the rotational speed command lower limit ωL can be easily obtained from the torque command value and the inverter temperature TI.
[0017]
The operation of the present embodiment will be described below.
2 and 3 are diagrams showing a flow of control for preventing overheating of the inverter performed by the motor control unit.
In order to start the vehicle on a slope, the driver depresses the accelerator pedal. The accelerator opening detection unit 1 outputs a signal of the accelerator opening to the torque request value calculation unit 2, and the torque request value calculation unit 2 outputs the signal as a torque request value τ1.
In addition, the motor rotation speed detection unit 11 outputs the rotation speed ω of the motor 9 and the inverter temperature detection unit 10 outputs the inverter temperature TI of the inverter 8 to the motor control unit 20 every moment.
[0018]
In step 101, the rotation speed command generation unit 3 checks whether the rotation speed ω of the electric motor 9 is equal to or less than a predetermined value ωo and the required torque value τ1 is equal to or more than a predetermined value τo.
If the rotational speed ω is equal to or less than the predetermined value ωo and the torque request value τ1 is equal to or more than the predetermined value τo, the process proceeds to step 102, and the torque command value switching flag Lτ is set to 1. If not, the routine proceeds to step 111, where the torque command value switching flag Lτ = 0 is set.
[0019]
The flow to step 102 is that the rotation speed ω of the electric motor 9 is lower than the creep speed of the vehicle, even though the driver has depressed the accelerator to the accelerator opening or more corresponding to the start of the vehicle on a normal flat ground ( The rotation speed command generation unit 3 detects that the rotation speed is substantially zero, and in order to avoid the occurrence of the locked state of the electric motor 9, the driving state of the vehicle is maintained while the driver depresses the accelerator pedal, and the inverter 8 is driven. Means that control is started to avoid a state in which current flows only through the one-phase switching element.
The flow to step 111 means normal torque control in which the rotation speed ω of the electric motor increases according to the depression amount of the accelerator pedal and the vehicle starts moving.
[0020]
In step 103, the rotation speed command generator 3 sets a predetermined provisional target rotation speed ω1 as a candidate for a rotation speed command value for preventing the inverter 8 from overheating.
In step 104, the rotational speed command lower limit value calculator 12 reads the inverter temperature TI from the inverter temperature detector 10.
In step 105, the rotational speed command lower limit value calculator 12 reads the previous torque command value τ2 from the torque command value calculator 5. Immediately after entering the flow of step 102, since the torque command value τ2 in the torque command value calculation unit 5 is undefined, the torque request value τ1 is substituted at that time.
[0021]
In step 106, the rotation speed command lower limit value calculation unit 12 calculates the rotation speed command lower limit value ωL, which is the minimum rotation speed of the electric motor 9 that is allowed to prevent overheating of the inverter 8 corresponding to the previous torque command value τ2 and the inverter temperature TI. It is obtained from the built-in data and is output to the rotation speed command restriction processing unit 4.
In step 107, the rotation speed command restriction processing unit 4 checks whether the rotation speed command lower limit value ωL is equal to or less than the provisional target rotation speed ω1 that is a candidate for the rotation speed command value.
If ωL ≦ ω1, the process proceeds to step 108, where the rotational speed command value ω2 = ω1, otherwise, the process proceeds to step 109, where the rotational speed command value ω2 = ωL, and the rotational speed command value ω2 is It is output to the command value selector 6.
[0022]
At the beginning when the torque command value switching flag becomes Lτ = 1, the locked state or the ultra low speed rotation state of the electric motor 9 hardly continues, so the inverter temperature TI is not high and the rotation speed command lower limit value ωL is ωL ≦ ω1. Yes, the flow is to step 108.
When the inverter temperature TI rises while the locked state or the ultra low speed rotation state continues, the rotation speed command lower limit value ωL becomes ωL> ω1, and the flow proceeds to step 109.
Therefore, as the locked state or the ultra-low speed rotation state of the electric motor 9 continues, the rotation speed command lower limit value ωL having a larger value is calculated in step 106, and is set as the rotation speed command value ω2 in step 109.
[0023]
After steps 108 and 109, the process proceeds to step 110.
In step 110, the torque command value calculation unit 5 calculates a new (current) torque command value τ2 by PI calculation from the difference between the rotation speed ω of the electric motor 9 and the rotation speed command value ω2. The torque command value calculator 5 calculates a larger torque command value τ2 as the deviation between the rotation speed ω of the electric motor 9 and the rotation speed command value ω2 is larger.
After step 110, the process proceeds to step 112.
After step 101, the process proceeds to step 111. If the torque command value switching flag Lτ = 0, the process proceeds to step 112.
[0024]
In step 112, the torque command value selector 6 confirms the state of the torque control. That is, it is checked whether the torque command value switching flag Lτ = 1.
When the torque command value switching flag Lτ = 1, the process proceeds to step 113, and otherwise, the process proceeds to step 116.
In step 113, the torque command value selection unit 6 checks whether the rotation speed ω of the electric motor 9 is equal to or more than the rotation speed command value ω2.
[0025]
If the rotation speed ω is less than the rotation speed command value ω2, the process proceeds to step 114, where the value of the torque command value τ2 from the torque command value calculation unit 5 is set as the torque command value τc to be output to the inverter control unit 7; Proceed to.
If the rotation speed ω is equal to or greater than the rotation speed command value ω2, the process proceeds to step 115, where the torque command value switching flag Lτ is reset to 0, and the process proceeds to step 116.
[0026]
In step 116, the torque command value selection unit 6 sets the torque request value τ1 from the torque request value calculation unit 2 as the torque command value τc to be output to the inverter control unit 7, and proceeds to step 117.
In step 117, the torque command value selecting section 6 outputs the torque command value τc to the inverter control section 7, and the inverter control section 7 controls the inverter 8 based on the input torque command value τc to drive and control the electric motor 9. .
Thereby, in the case of torque control (Lτ = 1) for preventing the inverter temperature from excessively rising, the electric motor 9 is driven with the target of the torque command value τ2 larger than the torque request value τ1 corresponding to the accelerator opening, and the motor 9 is released from the locked state. The rotation speed ω increases in the direction of the rotation.
[0027]
In step 118, the torque command value selector 6 confirms the state of the torque control.
If the torque command value switching flag Lτ = 1, the process returns to step 104 to continue the torque control for preventing the inverter from overheating.
When the torque command value switching flag Lτ = 0, a series of torque control for preventing the inverter from overheating is ended. That is, when the flow of the torque control for preventing the inverter overheating is repeated and the rotation speed ω of the electric motor 9 becomes ω2 or more, the torque request value τ1 according to the accelerator opening is set as the torque command value τc to the inverter 8. And performs torque control according to the accelerator operation of the driver.
[0028]
The accelerator opening detection unit 1 and the required torque value calculation unit 2 of the present embodiment are the first required torque calculation unit of the present invention, the inverter temperature detection unit 10 is the temperature detection unit, and the motor rotation speed detection unit 11 is the rotation speed. Steps 101, 102 and 111 of the flow constitute a determination means, steps 103 to 110 constitute a second required torque calculation means, and steps 112 to 118 constitute an inverter control means. In particular, steps 104, 105 and 106 constitute a rotation speed calculating means, and steps 107, 108 and 109 constitute a rotation speed selecting means.
Further, the predetermined rotation speed ωo is the first rotation speed of the present invention, the provisional target rotation speed ω1 is the second rotation speed, the rotation speed command lower limit ωL is the third rotation speed, and the torque request value τ1 is The torque command value τ2 corresponds to the first torque request value and the second torque request value.
[0029]
As described above, according to the present embodiment, when the electric motor 9 starts the locked state or enters the ultra-low-speed rotation state due to an insufficient amount of depression of the accelerator pedal at the time of starting on a slope, the rotation speed command generation unit 3 determines the inverter temperature. The start of torque control for preventing excessive rise is determined, and the torque control to the inverter 8 is set so that the rotation speed ω is equal to or higher than ω1, and the inverter temperature TI due to a rise in the temperature of a specific one-phase switching element due to one-phase conduction is reduced. The phenomenon of rising can be avoided.
[0030]
In particular, since the rise in the temperature of the switching element is correlated with the integral value of the current flowing through the one-phase switching element during the energizing time, the rotation speed command lower limit value calculation unit 12 reflects the current inverter temperature TI, The command lower limit value ωL is calculated, and the rotation speed command limit processing unit 4 compares the rotation speed command lower limit value ωL with the rotation speed ω1 to select the higher rotation speed and sets the higher rotation speed as the rotation speed command value ω2. Overtemperature is reduced.
That is, it is possible to prevent the locked state from being caused when climbing a hill, to reduce the possibility of torque reduction due to a decrease in the inverter output of the over-temperature protection function of the inverter 8, and to smoothly climb the hill.
[0031]
Further, even when the flow of the torque control for preventing the inverter temperature from excessively rising due to the insufficient amount of depression of the accelerator pedal is started, if the rotation speed ω of the electric motor 9 exceeds the rotation speed command value ω2, that is, the vehicle starts moving and the inverter temperature rises excessively. When the rotational speed can be avoided, the torque command value selection unit 6 switches to the normal torque control and controls the inverter 8 based on the torque request value τ1 corresponding to the accelerator opening. It can be done in a short time.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a control device for a vehicle electric motor according to an embodiment of the present invention.
FIG. 2 is a flowchart showing the operation of the embodiment.
FIG. 3 is a flowchart showing the operation of the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Accelerator opening detection part 2 Required torque value calculation part 3 Revolution number command generation part 4 Revolution number command restriction processing part 5 Torque command value calculation part 6 Torque command value selection part 7 Inverter control part 8 Inverter 9 Motor 10 Inverter temperature detection part 11 Motor speed detection unit 12 Speed command lower limit value calculation unit 20 Motor control unit

Claims (3)

An inverter that controls driving power supplied to an electric motor provided in the vehicle;
First required torque calculating means for calculating a first required torque value for the electric motor based on a driver's accelerator operation amount;
Rotation speed detection means for detecting the rotation speed of the electric motor,
Determining means for determining that the first torque request value is equal to or greater than a predetermined torque value and that the rotation speed of the electric motor is equal to or less than a predetermined first rotation speed;
Second required torque calculating means for calculating a second required torque value based on a predetermined second rotational speed higher than the first rotational speed;
When the first required torque value is less than the predetermined torque value or the rotation speed of the electric motor is greater than the first rotation speed, the inverter is controlled based on the first required torque value, and When the required torque value is equal to or greater than the predetermined torque value and the number of revolutions of the electric motor is equal to or less than the first number of revolutions, an inverter control unit that controls the inverter based on the second required torque value. A control device for a motor for a vehicle, comprising: A temperature detecting unit for detecting a temperature of the inverter,
A second rotation torque calculating unit configured to calculate a third rotation speed of the electric motor in which an inverter does not overheat based on a previous second torque request value and a temperature of the inverter;
A rotation speed selection unit that compares the third rotation speed with the second rotation speed and selects a higher rotation speed;
2. The control device according to claim 1, wherein the second required torque value is calculated based on the rotation speed selected by the rotation speed selection means. The inverter control means determines that the first torque request value is equal to or greater than the predetermined torque value and the rotation speed of the electric motor is equal to or less than the first rotation speed, and then the rotation speed is determined by the rotation speed selection means. If the rotation speed is less than the selected rotation speed, the inverter is controlled based on the second torque request value,
The motor for a vehicle according to claim 2, wherein the inverter is controlled based on the first torque request value when the rotation speed of the motor is equal to or higher than the rotation speed selected by the rotation speed selection unit. Control device.

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