JP2002305802A - Drive for blushless dc motor for driving motor vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive for a brushless DC motor for motor vehicles which suppresses temperature increase of armature coils and a switching circuit, without giving a sense of incongruity to a driver. SOLUTION: In a drive for a brushless DC motor which PWM-controls drive currents to be caused to flow in armature coils Lu-Lw with respect to a throttle signal outputted by a throttle sensor 15, the drive currents are limited and the temperature increase of the armature coils Lu-Lw and the switching circuit 10 is suppressed by reducing the rate of increase of the duty radio of PWM control with respect to the increase of throttle opening with the increase of temperature, when the temperature of each armature coil Lu to Lw or the temperature of the switching circuit 10 exceeds a set value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to an electric scooter,
The present invention relates to a drive device for a brushless DC motor for an electric vehicle used as a drive source for an electric vehicle such as an electric vehicle.

[0002]

2. Description of the Related Art As is well known, a brushless DC motor includes a rotor having a magnet field and a stator having three or more phased armature coils. The rotor is rotated by switching the excitation phase of the armature coil accordingly.

A driving device for driving this type of motor includes a position detector for detecting a rotational angle position of a rotor with respect to a stator, and a DC power source and an armature for switching a phase in which a driving current flows from a DC power source to an armature coil. A switch circuit provided between the coil, a speed adjusting member operated when adjusting the rotation speed of the electric motor, and a displacement amount of the speed adjusting member detected as a throttle opening to correspond to the throttle opening. It is composed of a throttle sensor that outputs a throttle signal of a magnitude, and a controller that controls a switch circuit to switch a phase in which a drive current flows according to the output of the position detector to rotate the rotor. The controller includes a PWM control unit that controls the switch circuit so that the drive current is a PWM waveform current having a duty ratio calculated with respect to the throttle signal, and a switching angle of a phase through which the drive current flows with respect to the throttle signal. Control lead angle control means for performing control so as to shift by the calculated control lead angle with respect to a reference switching angle determined by the output of the position detector.

Here, the duty ratio of the drive current indicates the ratio of the ON time to the ON / OFF cycle of the drive current. The time when the drive current flows is ton, the time when the drive current is zero is toff, and the on / off cycle is T (= ton + toff)
, The duty ratio DF is DF = (ton / T)
× 100 [%] is defined.

[0005] In an electric vehicle, the rotational speed of the electric motor is adjusted by displacing a speed adjusting member such as an accelerator grip or an accelerator pedal. However, in order to improve the driving feeling of the vehicle and perform smooth driving, Rather than controlling the duty ratio DF of the drive current only for the displacement amount (throttle opening) α of the speed adjusting member, the rate of change of the duty ratio DF for the speed adjusting member depends on the rotation speed N [rpm] of the motor. The duty ratio DF is controlled with respect to both the throttle opening α and the rotation speed N so as to change the rotation speed.

When the duty ratio DF is controlled with respect to the throttle opening α and the rotation speed N as described above, the relationship between the throttle opening α, the rotation speed N, and the duty ratio DF of the driving current is determined. The given three-dimensional map is stored in the ROM, and using this map, the CPU uses the duty ratio DF for the rotation speed N and the throttle opening α.
Is calculated, and on / off control of the switch element of the switch circuit is performed so that the drive current is intermittently operated at the calculated duty ratio DF.

The broken line a in FIG. 5 shows an example of the relationship between the throttle opening α during normal operation and the duty ratio DF of the PWM control. In this example, the speed adjusting member is provided with play. From the adjustment start position O1, which is set slightly closer to the speed increasing side than the fully closed position, which is the lower limit position of the speed adjusting member, is set before the fully open position which is the higher limit position. Until the adjustment end position O2
The duty ratio DF of the PWM control is linearly increased from 0 to 100 [%] with respect to the throttle opening α.

In a brushless DC motor, a switching angle (electric angle) for switching the phase of an armature coil through which a drive current flows is shifted by a predetermined angle from a theoretical switching angle determined by the mechanical configuration of the motor. ing. The phase difference between the switching angle of the phase through which the drive current flows and the theoretical switching angle is called a control advance angle γ, and the control advance angle γ is generally set to the advance side.

In the brushless DC motor, the generated torque and the maximum rotational speed change depending on the control advance angle γ. When the control advance angle γ is set so as to increase the torque, the maximum rotational speed decreases and the control advance angle γ decreases. As the angle is advanced, the maximum rotation speed increases, but the generated torque decreases.

Normally, when a brushless DC motor is used as a drive source for an electric vehicle, a control advance angle γ at which a sufficiently large torque can be obtained at a low speed is set as a normal control advance angle γo, and rotation is performed. In the region where the speed exceeds the set value, the control advance angle γ is advanced with respect to the normal control advance angle γo in accordance with the increase in the rotational speed, and in the region where the rotational speed exceeds the set advance end rotational speed, the control advance proceeds. The angle advance amount is kept at the maximum value.

When performing the control advance angle control as described above, a three-dimensional map giving a relationship between the displacement amount (throttle opening) α of the speed adjusting member, the rotational speed N, and the control advance angle γ is used. The control advance angle γ is calculated for the detected value of the throttle opening and the detected value of the rotational speed using this map, and the control advance angle of the electric motor is calculated as the calculated control advance angle. Control to make them equal.

As described above, when the control is performed such that the control advance angle γ is advanced from the normal control advance angle γo in the region where the rotational speed exceeds the set value, the speed advancement of the speed adjusting member is performed on an uphill or the like. When the motor is operated with the maximum displacement (full throttle), the control lead angle γ is maintained at the maximum value, and the drive current of the motor exceeds the rated value. State. If this condition continues for a long time,
The temperature of the armature coil and the semiconductor switch element of the switch circuit rises and exceeds an allowable value, which may be damaged.

For this reason, a conventional motor driving device of this type is provided with a temperature sensor for detecting the temperature of a component to be monitored, such as a switch circuit and an armature coil, and the temperature t detected by the temperature sensor is set at a set value. When ts is exceeded, the upper limit value of the duty ratio DF of the drive current is reduced to limit the drive current as shown by the polygonal lines b to d in FIG. Is performed to suppress temperature rise. Line b in FIG.
And d are the detected temperatures t of the monitoring-required components respectively.
1, t2, t3 (t1 <t2 <t3).

However, even if the drive current is limited when the temperature rises, if the control advance angle is still advanced, a large amount of reactive current flows, so that the rotational speed is greatly reduced and the travel speed is limited. Occurs. In practice, it is desirable to minimize the decrease in the rotation speed when performing the temperature rise suppression control.

Therefore, as disclosed in Japanese Patent Application Laid-Open No. Hei 8-265919, the temperature of an armature coil and the temperature of a component of a switch circuit for turning on / off a driving current flowing through the armature coil are detected to detect the temperature. It has been proposed to perform control for delaying the control advance angle and control for reducing the duty ratio of the drive current when an abnormal rise in the drive current is detected.

If the control advance angle is retarded when an abnormal temperature rise occurs, the drive current decreases, so that the temperature rise of the armature coil and the switch element of the switch circuit can be suppressed. In addition, the method of reducing the drive current by retarding the control advance angle takes a smaller rotational speed than the method of reducing only the duty ratio of the drive current without delaying the control advance angle. Can be reduced, so that it is possible to prevent the feeling of operation from being deteriorated during the temperature suppression control.

If the retard amount of the control advance angle is too large, the reactive current becomes excessively large, which is not preferable. However, the control for retarding the control advance angle and the control for reducing the duty ratio of the drive current are used together. By doing so, it is not necessary to increase the retard amount of the control advance angle so much, and it is possible to prevent the reactive current from becoming excessive.

[0018]

As described above, in a brushless DC motor for an electric vehicle, the temperature of an armature coil and the temperature of a switch element of a switch circuit for switching an excitation phase of the armature coil abnormally rise. In order to prevent this, a control is performed to suppress the drive current when an abnormal rise in temperature is detected.However, in a conventional motor drive device of this type, the temperature of the parts requiring monitoring exceeds a set value. When this is detected, the upper limit value of the duty ratio that increases with an increase in the throttle opening is limited as shown by the polygonal lines b to d in FIG. When the throttle opening reaches a certain value when changing to the speed increasing side and increasing the throttle opening,
Even if the throttle opening is further increased, a state in which the duty ratio does not increase occurs. For example, the temperature t of the monitored component
When the throttle opening α exceeds the value at point B when the speed exceeds the set value ts and reaches t2, the duty ratio DF does not change even if the speed adjusting member is further operated to the speed increasing side. The vehicle speed cannot be changed by following the operation of the adjusting member.

As described above, in the conventional driving device, when the temperature rises, there is a region in which the speed cannot be adjusted by following the speed adjusting member.

An object of the present invention is to provide a drive device for a brushless DC motor for an electric vehicle, which can perform control for suppressing a rise in temperature of an armature coil and a switch element without giving a driver an uncomfortable feeling. It is in.

[0021]

SUMMARY OF THE INVENTION The present invention relates to a brushless DC motor for driving an electric vehicle, comprising a rotor having a magnet field and a stator having a multi-phase armature coil. A position detector to be detected, a switch circuit provided between the DC power supply and the armature coil for switching a phase in which a drive current flows from the DC power supply to the armature coil, and adjusting a rotation speed of the motor. A throttle sensor that detects the amount of displacement of the speed adjustment member as a throttle opening and outputs a throttle signal of a magnitude corresponding to the throttle opening; and a position detection to rotate the rotor. A controller that controls a switch circuit so as to switch a phase in which a drive current flows according to the output of the device, wherein the controller includes: Duty ratio calculation means for calculating a duty ratio of a drive current with respect to a throttle signal, and PWM control for controlling the switch circuit such that the drive current is a PWM waveform current having a duty ratio calculated with respect to a throttle signal And a driving device for a brushless DC motor for driving an electric vehicle.

According to the present invention, there is provided a temperature detector for detecting a temperature of a monitoring-required component selected from components which generate heat when a drive current flows, and a temperature detected by the temperature detector being equal to or higher than a set value. When the detected temperature is higher, the duty ratio calculated by the duty ratio calculator is detected so that the increase ratio of the duty ratio to the throttle opening calculated by the duty ratio calculator is smaller as the detected temperature is higher. And duty ratio correction means for correcting in accordance with the temperature.

When the duty ratio correcting means as described above is provided, when the temperature of the component requiring monitoring rises, the drive current can be limited to prevent the component from being damaged.

Further, as described above, when the rate of change of the duty ratio with respect to the throttle opening is reduced when the temperature rises, the throttle opening is set to 0 to 1 even when the temperature rises.
Since the duty ratio can be changed over the entire change range of 00 [%], it is possible to prevent a situation in which the vehicle speed does not change following the displacement of the speed adjusting member, and to make the driver feel uncomfortable when the temperature rises. The drive current can be limited without giving it, and the temperature rise suppression control can be performed.

In the case where there are a plurality of components requiring monitoring, a plurality of temperature detectors for detecting the temperatures of the plurality of components requiring monitoring are provided, and the temperature is detected by one of the plurality of temperature detectors. When the increase rate of the duty ratio calculated by the duty ratio calculation means with respect to the throttle opening is detected when the temperature of the monitored component is equal to or higher than the set value set for the monitored component, and the temperature is high. There is provided a duty ratio correction means for correcting the duty ratio calculated by the duty ratio calculation means in accordance with the detected temperature so as to make the duty ratio smaller.

It is preferable to select at least an armature coil and a switch circuit as the monitoring-required components.

When the armature coil and the switch circuit are selected as components requiring monitoring, a temperature detector for the armature coil provided to detect the temperature of the multi-phase armature coil and a temperature of the switch circuit are provided. And a switch circuit temperature detector for detecting when the temperature detected by the armature coil temperature detector is equal to or higher than the set value set for the armature coil, or for the switch circuit temperature detection. When the temperature detected by the switch becomes equal to or higher than the set value set for the switch circuit, the rate of increase in the duty ratio calculated by the duty ratio calculation means with respect to the throttle opening is higher when the detected temperature is higher. The duty ratio calculation means is configured to reduce the duty ratio.

In this case, the armature coil temperature detector is
As a configuration in which the temperature-sensitive resistance elements of the number of phases provided to detect the temperature of the armature coil of each phase are connected in parallel, the multi-phase It is preferable to detect the average temperature of the armature coil.

When the armature coil temperature detector is configured to detect only the temperature of the armature coil of a specific phase, the motor is locked and the temperature of the specific armature coil rises abnormally. However, when the temperature rises, it may not be possible to detect an abnormal rise in the temperature. However, as described above, the temperature-sensitive resistance elements for the number of phases are provided, and If the average temperature of the multi-phase armature coil is detected from the parallel combined resistance value, even if the temperature of a specific armature coil rises abnormally, a temperature detection signal reflecting the abnormal rise in temperature is obtained. So you can
The armature coil can be properly protected.

In order to detect the temperature of the switch circuit, the temperature of the heat sink to which the switch elements constituting the switch circuit are attached may be detected. The temperature detector for the switch circuit can also be constituted by a temperature-sensitive resistance element.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

In FIG. 1, 1 is a rotor 2 and a stator 3
And an outer rotor type brushless DC motor. The rotor 2 includes a flywheel 201 formed of a substantially cup-shaped ferromagnetic material, and a flywheel 201.
And a permanent magnet 202 attached to the inner periphery of the peripheral wall portion.
A pole magnet field 203 is configured.

The magnet field is not limited to two poles, but can be generally formed as 2 m poles (m is an integer of 1 or more).

In the illustrated example, the normal rotation direction of the rotor 2 is the direction of the arrow CCL (counterclockwise in FIG. 1).

The stator 3 has a stator core 301 having three teeth Pu to Pw radially protruding from an annular yoke.
And three-phase armature coils Lu to Lw wound around tooth portions Pu to Pw of the stator core, respectively.
The armature coils Lu to Lw are connected in a three-phase star connection. An outer peripheral portion of each tip of the teeth Pu to Pw of the stator core 301 is a stator magnetic pole 302, and these stator magnetic poles are opposed to the magnet field 203 via a predetermined gap.

In the illustrated example, the stator core has three poles. However, when the number of phases of the armature coils provided on the stator is set to 3, generally 3n (n is an integer of 1 or more) stator cores are provided. , And a configuration in which a three-phase armature coil is wound around the 3n teeth.

The flywheel 201 is provided with a boss (not shown) at the center of the bottom wall thereof, and the boss is connected to the drive wheel of the electric vehicle directly or via a reduction gear.

To detect the rotational angle position of the rotor 2 with respect to the stator 3, three-phase position detectors hu to hw are attached to the stator core 301.

Each position detector is arranged at an appropriate position according to the conduction angle (electrical angle) of the drive current flowing through the armature coil of each phase. For example, the position where the no-load induced voltage induced in each of the armature coils Lu to Lw with the rotation of the rotor 2 reaches a peak (the magnetic flux flowing from the magnet field 203 through the teeth around which the armature coils of each phase are wound). "180-degree switching control" in which a drive current flows through the armature coil of each phase in a section of 90 degrees (electrical angle) before and after the position where the zero passes through the zero point.
Is performed to rotate the motor, the center position of the magnetic poles at the tips of the teeth Pu, Pv, and Pw around which the three-phase armature coils Lu, Lv, and Lw are respectively wound is determined by the magnetic field of the rotor 2. A position detector for each phase is mounted so as to detect the rotational angle position of the rotor when the position coincides with the center position of each magnetic pole of the magnet.

As shown in the figure, when the armature coils Lu, Lv, and Lw are wound around three tooth portions Pu, Pv, and Pw, respectively, and a Hall IC is used as the position detectors hu, hv, and hw. Are the teeth Pu, Pv and Pw
The position detectors hw, hu, and hv are arranged at positions where the phase is advanced by 90 degrees in electrical angle with respect to the center of each of the magnetic poles, and a driving phase (a motor that flows a driving current) determined by the outputs of these position detectors The switching angle of the child coil phase) is set as a reference switching angle, and the control advance angle is calculated so that the actual switching angle is advanced or retarded with respect to this reference switching angle.

Reference numeral 10 denotes a switch circuit provided between the armature coils Lu to Lw and the DC power supply 11 for switching the excitation phase of the armature coil. This switch circuit includes an upper-stage switch element 10u having one end commonly connected. Or 10w,
One end is connected to the other end of each of the upper switch elements, and the lower switch element 10 is connected to the other end in common.
x to 10z, and a common connection point at one end of the upper switch elements 10u to 10w and a common connection point at the other end of the lower switch elements 10x to 10w are connected to the DC power supply 11, respectively. It is connected to the positive terminal and the negative terminal.

As the switch elements constituting the switch circuit, any switch elements that can be controlled on and off, such as MOSFETs, power transistors, and IGBTs, can be used. In the illustrated example, each switch element is a MOSF.
It consists of ET.

Since a regenerative current flows during braking of the electric vehicle,
A feedback diode 12u is connected to each of the upper switch elements 10u to 10w and the lower switch elements 10x to 10z.
To 12w and 12x to 12z are connected. When MOSFETs are used as the switch elements as shown in the figure, a parasitic diode formed between the drain and source of the FET can be used as these feedback diodes.

The illustrated DC power supply 11 comprises a battery B and a capacitor C1 connected to both ends of the battery.

In order to control the switch circuit 10, a controller 13 having a microcomputer and an input / output interface, and switch elements 10u to 10w of the switch circuit in accordance with a signal given from the controller 13.
And 10x to 10z drive signals (signals for turning on the switch elements) Su to Sw and Sx to S, respectively.
and a driver circuit 14 for providing position detection signals Hu to Hw obtained from the position detectors hu to hw, respectively.
w is input to the controller 13.

Reference numeral 15 denotes a throttle sensor for detecting a displacement amount of a speed adjusting member such as an accelerator grip or an axel petal for adjusting the speed of the electric vehicle as a throttle opening α.
The illustrated throttle sensor 15 includes a potentiometer in which a movable contact 15a is connected to a speed adjusting member. A DC constant voltage E obtained from a constant voltage DC power supply circuit (not shown) is applied to both ends of a potentiometer constituting the throttle sensor 15, and is proportional to the throttle opening α between the movable contact 15a of the potentiometer and the ground. The throttle signal Vα is obtained.
A throttle signal obtained from the throttle sensor 15 is input to the controller 13. The throttle signal is converted into a digital value Vth by an A / D converter provided in the controller 13, and is converted into a digital value Vth.
Is read in.

In the present invention, a temperature detector is provided for detecting the temperature of a component requiring monitoring selected from components that generate heat when a drive current flows.
Usually, at least the armature coil and the components of the switch circuit 10 are selected as the monitoring required components. In the example shown in the figure, temperature-sensitive resistance elements (temperature sensors) Rtu to Rtw having a negative temperature coefficient or a positive temperature coefficient so as to detect the respective temperatures of the three-phase armature coils Lu to Lw are connected to the respective phases. It is thermally coupled to the armature coil. The temperature-sensitive resistance elements Rtu to Rtw are connected in parallel with each other, and these temperature-sensitive resistance elements constitute a temperature detector for an armature coil. When the armature coil temperature detector is configured as described above, it is possible to detect a temperature corresponding to the average value of the temperatures of the three-phase armature coils Lu to Lw from the parallel combined resistance values of the temperature-sensitive resistance elements Rtu to Rtw. it can.

In order to detect the temperature of the armature coil, a temperature sensor may be provided so as to detect the temperature of the armature coil of any one phase. In the case where the temperature is detected, when the temperature of the armature coil of a specific phase abnormally rises due to the locked state of the electric motor, the abnormal temperature rise may not be detected. On the other hand, as described above, the temperature-sensitive resistance elements are thermally coupled to the three-phase armature coils, respectively, and these temperature-sensitive resistance elements are connected in parallel. Since the temperature corresponding to the average value of the temperatures can be detected, even when the temperature rises abnormally only in the armature coil of a specific phase, a temperature detection signal reflecting the abnormal rise can be obtained. .

The temperature-sensitive resistance elements respectively attached to the three-phase armature coils are connected in parallel as described above, and the temperature corresponding to the average value of the temperatures of the three-phase armature coils is determined from the parallel combined resistance value. Is detected, only one input port of the CPU of the controller 13 to be allocated for reading the temperature of the armature coil is required, so that the cost can be reduced by using a CPU having a small number of ports.

In the example shown in FIG.
In order to detect the temperature of 0 (the temperature of the switch element), a temperature-sensitive resistance element Rts is thermally coupled to a heat sink to which the constituent elements of the switch circuit 10 are attached, and the temperature-sensitive resistance element Rts is used for the switch circuit. A temperature detector is configured. The detection signal (change in resistance value in this example) obtained from the temperature detector for the switch circuit is transmitted to the controller 1 together with the detection signal obtained from the temperature detector for the armature coil.
3 has been entered.

The controller 13 is provided with a voltage application circuit for applying a constant voltage to both ends of a parallel circuit of the temperature-sensitive resistance elements Rtu to Rtw constituting the armature coil temperature detector. To Rtw (voltage in proportion to the parallel composite value of the temperature-sensitive resistance elements Rtu to Rtw) is read into the CPU of the microcomputer through the A / D converter as a temperature detection signal. Similarly, a circuit for applying a constant voltage to both ends of the temperature-sensitive resistance element Rts for detecting the temperature of the switch circuit is provided in the controller, and the voltage between both ends of the temperature-sensitive resistance element Rts is used as an A / D signal as a temperature detection signal. It is read by the CPU through the converter.

The controller 13 configures various means necessary for controlling the electric motor by causing the microcomputer to execute a predetermined program. FIG. 2 shows the overall configuration of the embodiment of FIG. 1 including various function realizing means realized by the controller 13 causing the microcomputer to execute a predetermined program.

The controller 13 measures the rotation speed N of the electric motor, for example, by measuring the intervals of generation of the rectangular wave position detection signals generated by the position detectors hu to hw.
The duty ratio DF of the drive current supplied to the armature coil of the brushless DC motor 1 based on the rotational speed N and the throttle opening information obtained from the digital value Vth of the throttle signal, and the control advance angle ( (Phase difference between the actual switching angle for switching the phase of the armature coil through which the drive current flows and the reference switching angle determined by the arrangement of the position detector)
and γ. The calculation of the duty ratio DF and the control lead angle γ are performed by a duty ratio calculation 3 for providing a relationship between the rotation speed N, the throttle opening, and the duty ratio DF, respectively.
This is performed by an interpolation method using a three-dimensional map for calculating a control lead angle, which provides a relationship between the rotational speed N, the throttle opening, and the control lead angle γ (all maps are stored in the ROM). .

The rotation speed detecting means 13a for detecting the rotation speed of the electric motor by the process of calculating the rotation speed among the programs executed by the microcomputer constituting the controller 13 is realized. The duty ratio calculating means 13b calculates the duty ratio of the drive current with respect to the value of the throttle signal and the rotational speed by the process of calculating the duty ratio using the duty ratio calculation map.
Is configured.

Further, the control lead angle calculating means 13c is constituted by calculating the control lead angle using the control lead angle calculation map.

The controller 13 also has a position detector hu.
, The excitation phase determining means 13d for determining the phase in which the drive current flows based on the output signals of the values .about.hw. The excitation phase determining means applies control lead angle calculating means 13c to the armature coil of the phase determined based on the output signals of the position detectors hu to hw.
A command signal for giving a drive signal to a predetermined switch element of the switch circuit 10 is given to the driver circuit 14 at a timing having the control advance angle calculated by the following. The driver circuit 14 supplies a drive signal to a predetermined switch element according to the command signal.

Further, in order to make the waveform of the drive current supplied to the motor 1 into a PWM waveform which is intermittent at the duty ratio calculated by the duty ratio calculation means 13b, the drive circuit 14 provides the drive element with a switch element for the switch circuit 10. A modulation unit 13e that performs PWM modulation of a signal waveform is provided.

FIGS. 3A to 3I show waveforms of a position detection signal when the brushless DC motor shown in FIG. 1 is driven by performing a 180-degree switching control, and each switch element of the switch circuit 10. FIG. 4 is a waveform diagram showing on / off operation waveforms. 3A to 3C show position detection signals Hu to Hw generated by the position detectors hu to hw, respectively.
FIGS. 3D to 3F respectively show the upper switch elements 10 u to 10 w of the switch circuit 10 when the angle at which the phase of the armature coil for flowing the drive current is switched is set as a reference switching angle. Of FIG. FIGS. 3G to 3I show the on / off operations of the lower switch elements 10x to 10z of the switch circuit 10, respectively.

The excitation phase determining means 13d performs a logical operation on the position detection signals shown in FIGS. 3 (A) to 3 (C) so that each of the switch elements of the switch circuit 10 is turned on and off. Is determined, and a drive signal is applied to each switch element in a section where each switch element is turned on.

In the example shown in the figure, the duty ratio calculator 13b calculates a drive signal given from the driver circuit 14 to the lower switch elements 10x to 10z in order to perform PWM control of the drive current. The signal is modulated into a PWM waveform that is intermittent at a duty ratio, and the lower switch element is turned on and off at a predetermined duty ratio.

In the example shown in FIG. 3, in the program executed by the microcomputer of the controller, the process of realizing the duty ratio calculating means 13b and the drive signals given to the switching elements 10x to 10z are calculated by the duty ratio calculating means. Controlling the switch circuit so that the driving current is changed to a PWM waveform current having a duty ratio calculated by the duty ratio calculating means, by the process of realizing the modulation means 13e for modulating the waveform into an intermittent waveform with the duty ratio. Means are configured.

In the brushless DC motor, the maximum generated torque and the maximum rotational speed change depending on the control advance angle γ. In general, motor applications and required torque characteristics,
Alternatively, the magnitude of the control advance angle is set in accordance with the required maximum rotation speed or the like. In the case of a brushless DC motor that drives an electric vehicle, the control advance angle γ is fixed to the normal control advance angle γo when the rotational speed of the motor is equal to or less than the set value, and the advance of the motor at the set rotational speed is started. The control advance angle γ is advanced from the normal control advance angle γo as the rotational speed increases in a range exceeding the rotational speed, and the control advance angle proceeds in a range in which the rotational speed of the electric motor is equal to or more than the set advance end rotational speed. In many cases, the control advance angle γ is controlled in accordance with the rotation speed so that the amount of advance of the angle is fixed at the set maximum value.

When the control advance angle γ is controlled, the switching angle for switching the phase through which the drive current flows is determined by the control advance angle calculated for the throttle signal with respect to the reference switching angle determined by the output of the position detector. Control lead angle control means for controlling the shift is provided in the controller 13.

The control advance angle control means includes, among a series of steps of a program executed by the CPU of the controller 13, a step of realizing the control advance angle calculation means 13 c and a control advance angle calculated by the control advance angle calculation means. Determining the timing for switching the phase through which the drive current flows based on the angle and the reference switching angle determined by the excitation phase determining means 13d.

How to set the normal control advance angle γo is arbitrary, but generally, in order to increase the torque at the start of the electric vehicle, the control advance angle at which the maximum torque is obtained is set to the normal control advance angle. The lead angle is γo.

When the control is performed such that the control advance angle γ is advanced beyond the normal control advance angle γo in a region where the rotational speed N exceeds the set value, the amount of displacement of the speed adjusting member to the speed increasing side on an uphill or the like is reduced. When operating at the maximum state (full throttle state), the advance amount of the control advance angle γ is maintained at the maximum value, and the drive current of the electric motor exceeds the rated value . If such a state continues for a long time, the temperature of the armature coil and the switch element of the switch circuit rises and exceeds an allowable value, which may be damaged.

Therefore, in the present invention, the armature coil L
An armature coil temperature detector (in the illustrated example, configured by temperature-sensitive resistance elements Rtu to Rtw) for detecting temperatures u to Lw, and a switch circuit temperature detector for detecting the temperature of the switch circuit 10. (Configured with a temperature-sensitive resistance element Rts), the temperature detected by the armature coil temperature detector is lower than the set value set for the armature coil, and When the temperature detected by the temperature detector is lower than the set value set for the switch circuit, the duty ratio calculated by the duty ratio calculation means is left as it is, and the temperature is detected by the armature coil temperature detector. When the temperature exceeds the set value set for the armature coil, or the temperature detected by the switch circuit temperature detector is set for the switch circuit. When it is above set value, the duty ratio calculation unit 1 so as to reduce as when the temperature detected an increased rate to the throttle opening degree of the computed duty ratio is high by the duty ratio calculation unit
There is provided a duty ratio correcting means 13f for correcting the duty ratio calculated by 3b according to the detected temperature.

In order to perform the above control, for example,
Duty ratio D calculated by duty ratio calculation means
A correction coefficient calculation map that gives a relationship between the correction coefficient K (<1) multiplied by F and the detected temperature t is created for each of the armature coil and the switch circuit, and these maps are stored in the ROM. Let it be. Then, when the temperature detected by the armature coil temperature detector is equal to or higher than the set value set for the armature coil, the armature coil correction coefficient calculation map is used to calculate the temperature of the armature coil. A correction coefficient K is calculated for the temperature detected by the temperature detector, and the corrected duty ratio DF ′ (= K × DF). When the temperature detected by the switch circuit temperature detector is equal to or higher than the set value set for the switch circuit, the switch circuit temperature detector detects the temperature using the switch circuit correction coefficient calculation map. A correction coefficient K is calculated for the calculated temperature, and the calculated correction coefficient K is calculated by the duty ratio D calculated by the duty ratio calculating means.
The corrected duty ratio DF ′ (=
K × DF). The PWM control means controls the switch circuit so that the duty ratio of the drive current becomes equal to the duty ratio DF 'after the correction as described above.

FIG. 4 shows an example of the relationship between the duty ratio (DF or DF ') and the throttle opening α when the control for correcting the increase ratio of the duty ratio according to the detected temperature is performed as described above. It was shown to. In the figure, a polygonal line a indicates a duty ratio DF and a throttle opening α calculated by the duty calculating means when the detected temperature (for example, the temperature of the armature coil) t is equal to or less than the set value ts (normal).
The relationship is shown.

The broken lines b to d show the relationship between the corrected duty ratio DF 'and the throttle opening α when the detected temperatures t are t1, t2 and t3 (t1 <t2 <t3), respectively. .

As is apparent from FIG. 4, according to the present invention, when the temperature becomes equal to or higher than the set value, the duty ratio at the time when the throttle is fully opened is increased as shown by the broken lines b to d in FIG. Accordingly, the driving current can be limited by reducing the driving current. Further, over the entire change range of the throttle opening from 0 to 100%, the duty ratio DF continuously changes following the throttle opening to obtain a characteristic that reaches the maximum value when the throttle is fully opened. In addition, at the time of temperature rise, it is possible to prevent a state in which the vehicle speed does not change even if the speed adjusting member is displaced, and to perform the temperature rise suppression control without giving the driver an uncomfortable feeling.

In the above example, the temperature detector is constituted by a temperature-sensitive resistance element. However, the temperature detector may be constituted by using another temperature sensor such as a thermocouple.

In the above example, the drive current of the PWM waveform is obtained by turning on and off the lower switch element of the switch circuit. However, the drive current of the PWM waveform is obtained by turning on and off the upper switch element of the switch circuit. May be obtained, and a drive current having a PWM waveform may be obtained by turning on and off both the upper switching element and the lower switching element.

In the above example, the Hall IC constituting the position detector is arranged at a position advanced by 90 in the armature angle with respect to the center of the tooth portion on which the armature coil of each phase is wound. It is sufficient that the detector detects the rotational angle position of the rotor with respect to the stator, and the arrangement position is not limited to the above example.

In the above example, the 180-degree switching control is performed. However, the driving method of the brushless DC motor is not limited to the above example, and for example, the teeth around which the armature coils of each phase are wound. The present invention is also applicable to the case where the motor is rotated by performing "120-degree switching control" in which a drive current is applied to the armature coil of each phase in a section of 60 degrees (electrical angle) before and after the position where the magnetic flux flowing through the section passes through the zero point. Of course it can be applied.

In the above example, the temperature-sensitive resistance elements Rtu to Rtw (temperature sensors) are thermally coupled to each of the three-phase armature coils, and these temperature-sensitive resistance elements are connected in parallel. Configured the temperature detector for the armature coil,
The present invention is not limited to the case where the armature coil temperature detector is configured as described above, and separately detects the temperature detection signals obtained from the temperature-sensitive resistance elements respectively attached to the three-phase armature coils. The temperature is input to the CPU of the controller 13 and individually monitored by the CPU to correct the value of the throttle signal when the temperature of the armature coil of any phase exceeds a set value. May be performed.

In the above example, a Hall IC is used as the position detector, but a position detector such as a photo encoder may be used instead of the Hall IC.

The electric vehicle to which the present invention is applied may have a structure in which the output of the electric motor is directly transmitted to the driving wheels of the vehicle.
The output of the electric motor may be transmitted to the drive wheels via a reduction gear.

In the above example, a three-phase brushless motor is taken as an example, but the number of armature coils in the present invention is arbitrary.

[0080]

As described above, according to the present invention, there is provided a temperature detector for detecting the temperature of a monitoring-required component whose temperature rises due to the application of a drive current, and opening the throttle when the temperature of the monitoring-required component increases. A means for correcting the duty ratio so as to reduce the rate of increase of the duty ratio with respect to the temperature is provided. Therefore, even when the temperature of the monitoring target component exceeds the set value, the throttle opening is reduced from 0 to 100%. The duty ratio can be changed over the entire change range. Therefore, it is possible to prevent a situation in which the vehicle speed does not change even when the speed adjusting member is displaced when the temperature rises, and to perform the temperature rise suppression control without giving the driver an uncomfortable feeling.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a block diagram showing an overall configuration of the embodiment of FIG. 1 including a function realizing means realized by a microcomputer of a controller.

FIG. 3 is a waveform diagram showing a waveform of a position detection signal in the brushless DC motor of FIG. 1, and an ON / OFF operation waveform of each switch element of a switch circuit.

FIG. 4 is a diagram showing a relationship between a duty ratio of PWM control and a throttle opening in the present invention.

FIG. 5 is a diagram showing a relationship between a duty ratio of PWM control and a throttle opening in a conventional driving device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Brushless DC motor, 2 ... Rotor, 3 ... Stator, Lu-Lw ... Armature coil, hu-hw ... Position detector, 10 ... Switch circuit, 13 ... Controller, 15 ...
Throttle sensor, Rtu-Rtw, Rts ... temperature-sensitive resistance element.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H115 PA08 PC06 PG04 PI16 PU01 PU21 PV09 PV23 QN02 QN04 RB22 SE03 TO05 TO21 TU12 5H560 AA08 BB04 BB07 BB12 DA02 DC05 DC13 EB01 EB05 EC10 GG01 GG04 JJ06 XA02 XA02 XA02 XA02 XA02

Claims (4)

[Claims] 1. A brushless DC motor for driving an electric vehicle, comprising: a rotor having a magnet field and a stator having a multi-phase armature coil; a position detector for detecting a rotation angle position of the rotor with respect to the stator; A switch circuit provided between the DC power supply and the armature coil to switch a phase in which a drive current flows from the power supply to the armature coil, and a speed adjusting member operated when adjusting the rotation speed of the motor. A throttle sensor that detects a displacement amount of the speed adjusting member as a throttle opening and outputs a throttle signal of a magnitude corresponding to the throttle opening, and an output of the position detector to rotate the rotor. A controller that controls the switch circuit so as to switch a phase in which the drive current flows, wherein the controller A duty ratio calculator for calculating a duty ratio of the drive current with respect to a signal; and a PWM for controlling the switch circuit so that the drive current is a PWM waveform current having a duty ratio calculated with respect to the throttle signal. A driving device for a brushless DC motor for driving an electric vehicle, comprising: a temperature detector that detects a temperature of a monitoring-required component selected from components that generate heat when the driving current flows; and When the temperature detected by the temperature detector is equal to or higher than the set value, the rate of increase of the duty ratio calculated by the duty ratio calculation means with respect to the throttle opening is set to be smaller as the detected temperature is higher. A duty for correcting the duty ratio calculated by the duty ratio calculation means according to the detected temperature. A drive device for a brushless DC motor for driving an electric vehicle, comprising a ratio correction unit. 2. A brushless DC motor for driving an electric vehicle, comprising: a rotor having a magnet field and a stator having a multi-phase armature coil; a position detector for detecting a rotational angle position of the rotor with respect to the stator; A switch circuit provided between the DC power supply and the armature coil to switch a phase in which a drive current flows from the power supply to the armature coil, and a speed adjusting member operated when adjusting the rotation speed of the motor. A throttle sensor that detects a displacement amount of the speed adjusting member as a throttle opening and outputs a throttle signal of a magnitude corresponding to the throttle opening, and an output of the position detector to rotate the rotor. A controller that controls the switch circuit so as to switch a phase in which the drive current flows, wherein the controller A duty ratio calculator for calculating a duty ratio of the drive current with respect to a signal; and a PWM for controlling the switch circuit so that the drive current is a PWM waveform current having a duty ratio calculated with respect to the throttle signal. A driving device for a brushless DC motor for driving an electric vehicle, comprising: a plurality of temperatures for detecting temperatures of a plurality of monitoring-required components selected from components generating heat when the driving current flows. A detector, when the temperature of the monitoring-required component detected by any of the plurality of temperature detectors is equal to or higher than a set value set for the monitoring-required component, the duty ratio calculating means The duty ratio is set so that the rate of increase of the calculated duty ratio with respect to the throttle opening is smaller as the detected temperature is higher. That a duty ratio correcting means for correcting, depending on the temperature detected the computed duty ratio by duty ratio calculation unit, a drive apparatus for an electric vehicle driving brushless DC motor according to claim. 3. The drive device for a brushless DC motor for driving an electric vehicle according to claim 2, wherein the plurality of monitored parts are switch elements constituting the armature coil and the switch circuit. 4. A brushless DC motor for driving an electric vehicle, comprising: a rotor having a magnet field and a stator having a multi-phase armature coil; a position detector for detecting a rotation angle position of the rotor with respect to the stator; A switch circuit provided between the DC power supply and the armature coil to switch a phase in which a drive current flows from the power supply to the armature coil, and a speed adjusting member operated when adjusting the rotation speed of the motor. A throttle sensor which detects a displacement amount of the speed adjusting member as a throttle opening and outputs a throttle signal having a magnitude corresponding to the throttle opening, and a throttle sensor which rotates the rotor in accordance with an output of the position detector. A controller that controls the switch circuit so as to switch a phase in which the drive current flows, wherein the controller A duty ratio calculating means for calculating a duty ratio of the drive current with respect to a signal; and a PWM controlling the switch circuit such that the drive current is a PWM waveform current having a duty ratio calculated with respect to the throttle signal. A driving device for a brushless DC motor for driving an electric vehicle, the control device comprising: a temperature detector for an armature coil provided to detect a temperature of the multi-phase armature coil; and a temperature of the switch circuit. A temperature detector for a switch circuit for detecting the temperature of the armature coil when the temperature detected by the temperature detector for the armature coil is equal to or higher than a set value set for the armature coil, or the temperature detection for the switch circuit. When the temperature detected by the heater becomes equal to or higher than a set value set for the switch circuit, the duty ratio calculating means; Duty ratio correction for correcting the duty ratio calculated by the duty ratio calculating means in accordance with the detected temperature such that the increase ratio of the calculated duty ratio to the throttle opening degree becomes smaller as the detected temperature is higher. A driving device for a brushless DC motor for driving an electric vehicle, comprising: