JPH09240561A - Auxiliary force control device for motor-assisted vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the auxiliary force accurately corresponding to an external instruction value regardless of the motor characteristic by controlling a current feed circuit so that the current value fed to an electric motor becomes a throttle auxiliary current value. SOLUTION: A current value control means 200 feeds the detection signal corresponding to the current value flowing in a motor 44 to a current value calculating means 211 from a current detecting means 201 via an input I/F 210, calculates the current value of the motor 44, calculates the difference between the current value and the target current value obtained by a target current value calculating means 100 with a deviation calculating means 212, and calculates a controlled variable required to set the difference to 0 with a controlled variable calculating means 213. A current feed circuit 214 controls the current fed to the motor 44 based on the calculated controlled variable. The auxiliary force accurately corresponding to an external instruction value can be obtained regardless of the motor characteristic.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an auxiliary force control device for an electrically assisted vehicle having a human power drive system and an electric power drive system.

[0002]

2. Description of the Related Art An electric power assisted vehicle (for example, an electric power assisted bicycle) having a human power drive system for supplying pedal effort to drive wheels and an electric power drive system for supplying auxiliary power from an electric motor to drive wheels has been proposed. There is. In this type of vehicle, a throttle lever is disposed near the handle grip, etc., and a desired assist force is externally instructed by the throttle lever, and the electric motor is controlled so that the assist force corresponding to the instructed value is obtained. It is possible to do it.

In the control of the electric motor, the fact that a constant relationship is established between the voltage supplied to the motor and the rotational speed and generated torque of the motor is used to respond to the instruction value from the throttle lever. It is possible to generate an assisting force. That is, the rotation speed of the motor is detected, and the voltage value to be supplied to the motor required to obtain the assisting force corresponding to the indicated value at this rotation speed is obtained based on the above-mentioned fixed relationship, and the obtained voltage is PWM. It is supplied to the motor by duty ratio control.

[0004]

By the way, the characteristics of the motor, which is the auxiliary power source, are influenced by the resistance of the brush, the resistance of the armature winding, and the like, and the characteristics vary even if they are of the same model and specifications. Therefore, when the voltage control by the PWM duty ratio control is adopted and the assisting force of each vehicle is compared under a certain condition (vehicle speed, throttle opening), there is a variation in the assisting force due to the characteristics of each motor. There is concern about the problem of easy occurrence.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide an auxiliary force control device for an electrically assisted vehicle that can obtain an auxiliary force that accurately corresponds to an external instruction value regardless of motor characteristics. I am trying.

[0006]

According to a first aspect of the present invention, there is provided an electric assist system including a human power drive system for supplying pedal effort to drive wheels and an electric power drive system for supplying assist force from an electric motor to drive wheels. In a vehicle assist force control device, an assist force instructing means for externally instructing a magnitude of an assist force and a throttle assist for obtaining a throttle assist current value necessary to obtain a throttle assist force instructed by the assist force instructing means. The present invention is characterized by including current value calculation means and current value control means for controlling the current supply circuit so that the current value supplied to the electric motor becomes the throttle auxiliary current value.

According to a second aspect of the present invention, the pedal force detecting means for detecting the pedal effort, the pedal assist force calculating means for obtaining the pedal assist force based on the pedal force from the pedal force detecting means, and the pedal assist are provided. A pedal auxiliary current value calculating means for obtaining a pedal auxiliary current value required to obtain force,
The current value control means controls the current supply circuit so that the current value supplied to the electric motor becomes a target current value obtained by superimposing the throttle auxiliary current value and the pedal auxiliary current value.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings. 1 to 3 are views for explaining an assisting force control device for an electric assisted bicycle according to an embodiment of the present invention. FIG. 1 is a side view of the electric assisted bicycle, and FIG. 2 is a function of the assisting force control device. Configuration diagram, FIG. 3 is a block configuration diagram showing a specific configuration of the assist force control device.

In FIG. 1, reference numeral 1 is an electric power assisted bicycle, and a body frame 10 of the bicycle 1 is a head pipe 12.
A down tube 14 extending obliquely downward and rearward of the vehicle body from the head pipe 12, a seat tube 16 standing upward from a rear portion of the down tube 14, and a pair of left and right extending rearward from a rear end of the down tube 14. The rear arms 20 and 20 are provided with a pair of left and right seat stays 22 and 22 that connect the rear ends of the rear arms 20 and 20 and the upper end of the seat tube 16.

At the lower end of the head pipe 12, the front wheel 2 is attached.
A front fork 24, which supports 8 and has a steering handle 26 fixed to the upper end, is pivotally supported to the left and right. A seat post 30a is inserted into the seat tube 16 so that its height can be adjusted, and a saddle 30 is attached to the upper end of the seat post 30a. Further, a rear wheel 32 is rotatably mounted between the rear ends of the rear arms 20 and 20, and a hub 34 of the rear wheel 32 has an internal transmission built therein.

Reference numeral 40 denotes a power unit (electric power drive system) which is a power source of the bicycle 1, and the power unit 4
Reference numeral 0 denotes a power case 42, a permanent magnet type DC electric motor 44 which is integrally connected to the power case 42 and transmits a driving force to the rear wheels 32, a battery 64 which supplies a current to the electric motor 44, and The controller 54 controls the driving force of the electric motor 44.

The power case 42 is attached below the rear portion 14a of the down tube 14, and the electric motor 4 is attached.
4 is disposed inside the vehicle body cover 41 so as to project obliquely upward and upward, and is parallel to the rear portion 14a of the down tube 14. The controller 54 is mounted inside the vehicle body cover 41 so as to be located below the front portion 14b of the down tube 14.

The battery 64 has a large number of battery cells connected in series and built in the case. The battery case 60 is disposed in the space between the seat tube 16 and the front edge of the rear wheel 32. It is detachably stored inside. In addition,
The upper end opening of the battery case 60 is located between the left and right seat stays 22 and protrudes upward, and the battery 64 is mounted vertically between the left and right seat stays 22 and 22. It can be removed.

A crankshaft 46 is inserted through the power case 42 in the vehicle width direction, and crank arms 48 are provided at both ends thereof.
(Only one is shown) is fixed, and a crank pedal 50 is attached to each crank arm 48.
As a result, a human power drive system 75 that transmits the pedaling force applied to the crank pedal 50 to the rear wheel 32 via the chain 52 is configured.

The head pipe 12 of the vehicle body frame 10
A main switch 56 and a traveling mode changeover switch 63 are arranged in the vicinity of the connecting portion to the opening 41a formed in the vehicle body cover 41.
From the outside. A throttle lever (auxiliary force instruction means) 68 is rotatably disposed near the handle grip of the steering handle 26.

As shown in FIG. 2, the controller 54 is
Is a target current value calculating means 100 for obtaining a target current value required to obtain an auxiliary force corresponding to inputs from the throttle sensor 101, the pedaling force sensor 102, and the vehicle speed sensor 103, and the current value supplied to the motor 44 is It has a function as a current value control means 200 for controlling the current supply circuit 214 so that the target current value obtained by the calculation means 100 is obtained.

The target current value calculating means 100 has the following structure. The opening degree (instruction value) of the throttle lever 68 is detected by the throttle sensor 101 as a throttle auxiliary torque, and the input interface 113
When it is input via the throttle assist current value calculating means 114, the throttle assist current value necessary to obtain the above throttle assist torque at the vehicle speed at that time, that is, the motor rotation speed input from the vehicle speed sensor 103 is obtained. To be The throttle assist torque is set to a value proportional to the throttle opening, for example.

On the other hand, when the pedal effort detected by the pedal effort sensor 102 is input through the input interface 110, the pedal assist torque computing means 111 computes the pedal assist torque corresponding to the detected pedal effort. The pedal assist current value calculation means 112 obtains the pedal assist current value required to obtain the pedal assist torque at the vehicle speed at that time, that is, the motor rotation speed input from the vehicle speed sensor 103. The pedal assist torque is set to a value proportional to the pedal effort, for example.

Then, the superimposing means 115 superimposes the throttle assist current value based on the throttle command value and the pedal assist standard current value based on the pedal effort on the basis of a predetermined arithmetic expression or the like, thereby obtaining the target current value. As the calculation formula for the superposition, for example, a calculation formula is used in which the pedal assist current value is corrected to a smaller value as the throttle opening is larger and then added to the throttle assist current value.

The current value control means 200 is constructed as follows. When a detection signal corresponding to the current value flowing in the motor 44 is input from the current detecting means 201 via the input interface 210, the current value calculating means 211 calculates the current value flowing in the motor 44, and the current is calculated. The difference between the value and the target current value is calculated by the deviation calculating means 212, and the control amount necessary for making the difference 0 by the control amount calculating means 213 (for example, PW).
A duty ratio correction amount in M control) is calculated.
Then, according to the calculated control amount, the current supply circuit 21
4 controls the current flowing through the motor 44.

FIG. 3 shows a specific structure of the current detecting means 201 and the current supply circuit 214. In the figure, the current detecting means 201 has a shunt resistor 201a interposed between the motor 44 and the ground, and the shunt resistor 201a is provided.
The voltage across both ends of the
It is configured to be smoothed by 01c and input to the controller 54.

In this embodiment, since the shunt resistor 201a is provided between the motor 44 and the ground, the common-mode noise input to the differential amplifier 201b is reduced and the motor 4
A signal that accurately reflects the current value of 4 is obtained from the filter 201c.

The current supply circuit 214 includes a battery 64.
N-channel FET 21 between the positive electrode of
4a, a gate drive 214b for turning on and off the FET 214a is connected between the FET 214a and the CPU 250, and a bootstrap circuit 215 is connected to the gate drive 214b.
A flywheel diode 216 serves as a motor current path when the FET 214a is off.

The bootstrap circuit 215 uses the FE
This is to always apply a constant gate-source voltage to T214a regardless of the fluctuation of the source potential. The bootstrap circuit 215 is a step-down circuit 215 that steps down 24V of the battery to 12V DC voltage.
a, the backflow prevention diode 215b, and the step-down circuit 21
And a capacitor 215c charged by 5a.

According to the apparatus of this embodiment, first, the throttle assist current value required to obtain the throttle assist torque corresponding to the opening degree (instruction value) of the throttle lever 68 is obtained, and the pedal assist torque corresponding to the pedal effort is obtained. The pedal assist current value required to obtain the target current value is obtained, and the throttle and pedal assist current values are superimposed in accordance with a predetermined method to obtain the target current value. Then, the current supply circuit 214 is controlled by feedback control so that the value of the current flowing through the motor 44 becomes the target current value.

As described above, in the present embodiment, the current value is obtained as the control target value, and the current value is controlled so that the current value flowing through the motor 44 becomes the above target current value. It can be generated with high accuracy.

Further, in the present embodiment, the target current value calculation means 100 and the current value control means 200 are realized by software processing in the CPU of the controller 54, so that the apparatus cost can be reduced and the reliability of the control operation can be increased. Various processing contents can be added. For example, in the processing of the deviation calculating means 212, the current value detecting means 201 is out of order by providing a program that performs fail-safe processing when the difference between the target current value and the motor current value exceeds an allowable value. You can also respond to such accidents.

In the above embodiment, the throttle auxiliary current value obtained from the slot opening and the pedal auxiliary current value obtained from the pedal effort are superposed, but the mode changeover switch 63 is used to obtain the throttle opening. The throttle auxiliary current value can be used as it is or in the throttle input mode in which the target current value is obtained after a certain calculation process. This is the invention of claim 1.

Further, by the mode changeover switch 63, the above-mentioned superposition mode, the throttle input mode, and the pedal input mode in which the pedal assist current value obtained from the pedal depression force is used as it is or as a target current value after a certain arithmetic processing is carried out in three stages. It is also possible to switch to.

[0030]

As described above, according to the auxiliary force control device for an electrically assisted vehicle according to the invention of claim 1, when the auxiliary force is controlled based on an instruction value externally instructed, the auxiliary force is controlled. Since a corresponding target current value is obtained and the current value supplied to the electric motor is controlled so as to match the target current value, there is an effect that the instructed assisting force can be generated with high accuracy.

According to the second aspect of the present invention, the target current is obtained by superimposing the throttle assist current value for obtaining the assist force based on the indicated value and the pedal assist current value for obtaining the assist force based on the pedal effort. Since the value was calculated and the current value supplied to the electric motor was controlled to match the target current value, the desired auxiliary force can be generated with high accuracy.
By appropriately selecting the above-mentioned superposition method, it is possible to smooth the supply fluctuation of the assisting force and improve the driving feeling.

[Brief description of drawings]

FIG. 1 is a side view of an electric assist bicycle including an assist force control device according to an embodiment of the present invention.

FIG. 2 is a functional configuration diagram of the auxiliary force control device.

FIG. 3 is a block configuration diagram of the auxiliary force control device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electric assisted bicycle 40 Electric power drive system 44 Electric motor 68 Throttle lever (Assistance force indicating means) 75 Human power drive system 100 Target current value calculating means 102 Pedal force sensor (pedal force detecting means) 111 Pedal assist force calculating means 112 Pedal assist current value calculating Means 114 Throttle auxiliary current value calculation means 200 Current value control means 214 Current supply circuit

Claims (2)

[Claims] 1. An auxiliary force control device for an electrically assisted vehicle comprising a human power drive system for supplying pedal effort to a drive wheel and an electric power drive system for supplying an assist force from an electric motor to the drive wheel. Supplying to the electric motor, an assisting force instructing means for instructing the magnitude from the outside, a throttle assisting current value calculating means for obtaining a throttle assisting current value necessary to obtain the throttle assisting force instructed by the assisting force instructing means. And an electric current value control means for controlling the electric current supply circuit so that the electric current value to be controlled becomes the throttle auxiliary electric current value. 2. The pedal force detecting means for detecting the pedal effort, the pedal assist force calculating means for obtaining the pedal assist force based on the pedal force from the pedal force detecting means, and the pedal assist force for obtaining the pedal assist force according to claim 1. A pedal assist current value calculating means for obtaining a necessary pedal assist current value, and the current value control means sets a target current value to be supplied to the electric motor by superimposing the throttle assist current value and the pedal assist current value. An auxiliary force control device for an electrically assisted vehicle, which controls a current supply circuit so as to obtain a current value.