Motor control device

Abstract

In order to improve the responsiveness of motor driving for an electric vehicle, this motor control device comprises: (A) a smoothing unit that smooths a drive operation amount related to an operation input for the driving of a motor; (B) a generation unit that, in accordance with an increase or decrease in the drive operation amount, generates a component for emphasizing the increase or decrease; and (C) a control unit that controls the driving of the motor on the basis of the results of combining the smoothed drive operation amount and the component.

Description

Motor Control Device

[0001] The present invention relates to a motor control technique for an electric vehicle.

[0002] Conventionally, when a user gives an acceleration or deceleration command using an accelerator pedal, grips, brake pedal, brake lever, or the like, electric vehicles such as electric cars, hybrid cars, and electric motorcycles detect the amount of operation based on the force and displacement applied, and control the speed of the electric vehicle by changing the driving force of the motor in accordance with the amount of operation.

[0003] Furthermore, electrically assisted bicycles, which are an example of electrically assisted vehicles included in electric vehicles, can have an assist mode, a low-speed self-propelled mode for sidewalks only, a motorcycle mode for roadways, etc. In this assist mode, for example, the crank input torque generated by the pedaling force is directly used as rear wheel driving force via a chain or the like, and at the same time, acceleration / deceleration instructions are input to the control device, and the motor is controlled according to the crank input torque.

[0004] When an electric vehicle's speed drops unnoticed while cruising and the driver notices this, or when the speed fluctuates due to changes in the environment, such as on flat ground, uphill, or downhill, the motor's drive torque should be increased or decreased to achieve the desired speed. However, due to delays in the user's speed recognition or delays in issuing acceleration / deceleration instructions, the desired speed may not be achieved immediately. Therefore, it is desirable to be able to quickly respond to the rider's intentions by temporarily and automatically increasing or decreasing the motor's drive torque in response to the rider's acceleration / deceleration intentions. However, adopting a method that simply responds too sensitively to changes in the amount of operation results in greater fluctuations in drive torque during normal operation, causing jerky behavior and increasing power consumption, so it is preferable to avoid such a method.

[0005] Furthermore, in electrically assisted bicycles, the crank input torque is subject to periodic torque fluctuations, i.e., torque ripple, such that the torque reaches zero at the top and bottom dead centers of the crank. To suppress this ripple component, smooth the assist drive output, and maximize drive efficiency, the assist drive output is sometimes generated by smoothing the crank input torque (see, for example, Patent Document 1). In this case, a response delay inevitably occurs due to the smoothing filter, and even methods with relatively little response delay result in gradual rise and fall, resulting in an average delay of about a quarter rotation, hindering quick response. Furthermore, there may be a large difference in leg strength between the left and right legs, which can cause alternating fluctuations in the crank input torque, making it difficult to quickly and accurately grasp the user's acceleration / deceleration intentions.

[0006] For example, Patent Document 2 discloses an assist force control device for an electrically power-assisted vehicle, which includes a human-powered drive system that supplies pedal force to drive wheels, an electric power drive system that supplies assist force from an electric motor to the drive wheels, and an assist force control means that variably controls the assist force in accordance with the pedal force and vehicle speed. The assist force control device corrects the pedal force using a time derivative of the pedal force, or the pedal force corrected using the angular position of the pedal. This is said to provide a responsive and sharp assist feel. However, since the pedal force correction involves torque ripple, the correction is always performed even during constant-speed driving, and the control may not be responsive to the user's acceleration / deceleration intentions. For example, even if the user increases the amplitude of the pedal force, the assist force is reduced in the latter half of the torque ripple. Therefore, the pedal force is simply emphasized in harmonics, with the pedal force being accelerated in the first half and decelerated in the second half, in proportion to the speed, and this does not provide acceleration / deceleration assistance in line with the user's intentions. Furthermore, since torque ripple is maintained or increased, the driving efficiency is not good.

[0007] Furthermore, for example, Patent Document 3 discloses a technology for a hybrid vehicle having an engine and a motor. The technology sets a threshold value X for vehicle speed at a point where it is determined that the engine will exceed its maximum output, and adds an additional value corresponding to the rate of change in accelerator operation amount to an output command reference value corresponding to the accelerator operation amount only when the rate of change in accelerator operation amount exceeds the threshold X, thereby enabling appropriate acceleration to be achieved in response to the driver's accelerator operation. This technology provides assistance with the motor when it is determined that the engine will exceed its maximum output, but it cannot adequately respond to situations where the motor alone is used or deceleration is required. Furthermore, it cannot handle cases where there is ripple in the crank input torque corresponding to the operation amount, as in the case of an electrically assisted bicycle.

[0008] International Publication WO2012 / 086458 JP-A-9-290794 JP-A-2006-230101

[0009] Therefore, in one aspect, an object of the present invention is to provide a new control technique that improves the responsiveness of motor drive in an electric vehicle.

[0010] The motor control device according to the present invention includes (A) a smoothing unit that smooths a drive operation amount related to an operation input for driving a motor, (B) a generating unit that generates a component for emphasizing an increase or decrease in the drive operation amount in accordance with the increase or decrease, and (C) a control unit that controls the drive of the motor based on the result of combining the smoothed drive operation amount and the above-mentioned component.

[0011] FIG. 1 is a diagram showing the appearance of an electrically assisted bicycle, which is an example of an electrically assisted vehicle included in electric vehicles. FIG. 2 is a functional block diagram of a motor control device. FIG. 3 is a diagram showing an example of the configuration of a drive control unit according to a first embodiment. FIG. 4 is a diagram showing an example of the characteristics of a nonlinear response unit. FIG. 5 is a diagram showing a timing chart illustrating an example of operation in the first embodiment. FIG. 6 is a diagram showing an example of the configuration of a drive control unit according to a first modified example of the first embodiment. FIG. 7 is a diagram showing an example of the configuration of a drive control unit according to a second embodiment. FIG. 8 is a diagram showing a timing chart illustrating an example of operation in the second embodiment. FIG. 9 is a diagram showing an example of the configuration of a drive control unit according to a first modified example of the second embodiment. FIG. 10 is a diagram showing an example of the configuration of a drive control unit according to a second modified example of the second embodiment. FIG. 11 is a diagram showing a timing chart illustrating an example of operation in the second modified example of the second embodiment. FIG. 12 is a diagram showing a timing chart illustrating a problem in the second embodiment. FIG. 13 is a diagram showing an effect of the second modified example of the second embodiment. FIG. 14 is a diagram showing a timing chart illustrating another problem in the second embodiment. FIG. 15 is a diagram showing an example of the configuration of a drive control unit according to the third embodiment. FIG. 16 is a diagram showing a timing chart illustrating an example of operation in the third embodiment. FIG. 17 is a diagram showing an example of the configuration of a drive control unit according to Modification 1 of the third embodiment. FIG. 18 is a diagram showing a timing chart illustrating an example of operation in Modification 1 of the third embodiment. FIG. 19 is a diagram showing a timing chart for explaining a problem with Modification 1 of the third embodiment. FIG. 20 is a diagram showing an example of the configuration of a drive control unit according to the fourth embodiment. FIG. 21 is a diagram showing a timing chart illustrating an example of operation in the fourth embodiment. FIG. 22 is a diagram showing an example of the configuration of a drive control unit according to the fifth embodiment. FIG. 23 is a diagram showing a timing chart illustrating an example of operation in the fifth embodiment. FIG. 24 is a diagram showing an example of the configuration of a drive control unit according to Modification 1 of the fifth embodiment.

[0012] [Embodiment 1] Figure 1 is an external view showing an example of an electrically assisted bicycle that can be operated in a self-propelled motorcycle mode and an assist mode. This electrically assisted bicycle 1 is equipped with a motor drive unit. The motor drive unit has a battery pack 101, a motor control unit 102, a crank torque sensor 103, a crank rotation sensor 104, a motor 105, a display 106, a brake sensor 107, and an accelerator position detection unit 108.

[0013] The electrically assisted bicycle 1 also has a front wheel, a rear wheel, a headlight, a freewheel, a transmission, and the like.

[0014] The battery pack 101 is, for example, a lithium ion secondary battery, but may be other types of batteries, such as a lithium ion polymer secondary battery, a nickel-metal hydride battery, etc. The battery pack 101 supplies power to the motor 105 via the motor control device 102, and is also charged by the regenerated power from the motor 105 via the motor control device 102 during regeneration.

[0015] The crank torque sensor 103 is provided near the crankshaft, detects the pedal force applied by the user (i.e., crank input torque), and outputs the detection result to the motor control device 102. Similarly to the crank torque sensor 103, the crank rotation sensor 104 is provided near the crankshaft, and outputs a signal corresponding to the rotation of the crank to the motor control device 102.

[0016] The motor 105 is, for example, a well-known three-phase DC brushless motor, and is attached to, for example, the front wheel of the electrically assisted bicycle 1. The motor 105 rotates the front wheel, and the rotor is connected to the front wheel so that the rotor rotates in response to the rotation of the front wheel. Furthermore, the motor 105 is equipped with a rotation sensor such as a Hall element, and outputs rotor rotation information (for example, a Hall signal) to the motor control device 102.

[0017] The brake sensor 107 detects a brake operation by the user and outputs a brake signal related to the brake operation (for example, a signal indicating whether or not a brake operation is being performed) to the motor control device 102. Specifically, the brake sensor 107 is a sensor using a magnet and a reed switch.

[0018] The accelerator opening detection unit 108 detects the rotation of the accelerator grip by the user, and outputs a signal relating to the corresponding accelerator opening to the motor control device 102 .

[0019] The display 106 is also called an operation panel, and typically includes a button for switching the light on and off, a button for turning the power on and off, a liquid crystal display, an LED (Light Emitting Diode) for displaying the degree of assistance in the assist mode, etc. In this embodiment, a button for switching between the self-propelled motorcycle mode and the assist mode may also be provided.

[0020] In the assist mode, the motor control device 102 performs a predetermined calculation based on signals from the rotation sensor of the motor 105, the crank torque sensor 103, the crank rotation sensor 104, etc., and in the self-propelled motorcycle mode, it performs a predetermined calculation based on signals from the rotation sensor of the motor 105 and the accelerator opening detection unit 108, etc., to control the drive of the motor 105 and also control regeneration by the motor 105.

[0021] 2 shows the configuration related to the motor control device 102 according to this embodiment. The motor control device 102 includes a FET (Field Effect Transistor) bridge 1030 and a control unit 1020. The FET bridge 1030 includes a high-side FET (Suh) and a low-side FET (Sul) that perform switching for the U-phase of the motor 105, a high-side FET (Svh) and a low-side FET (Svl) that perform switching for the V-phase of the motor 105, and a high-side FET (Swh) and a low-side FET (Swl) that perform switching for the W-phase of the motor 105. This FET bridge 1030 is an inverter for the motor 105 and constitutes part of a complementary switching amplifier.

[0022] The control unit 1020 has a calculation unit 1021, a crank rotation input unit 1022, an accelerator opening input unit 1023, a motor rotation input unit 1024, a motor drive waveform generation unit 1025, a torque input unit 1027, a brake input unit 1028, and an AD (Analog-Digital) input unit 1029.

[0023] The crank rotation input unit 1022 digitizes the crank rotation phase angle (which may include a signal indicating the rotation direction) from the crank rotation sensor 104 and outputs it to the calculation unit 1021. The motor rotation input unit 1024 digitizes signals (e.g., rotation phase angle, rotation speed, rotation direction, etc.) related to the rotation of the motor 105 (the rotation of the front wheel in this embodiment) from the Hall signal output by the motor 105 and outputs them to the calculation unit 1021 and also to the motor drive waveform generation unit 1025. The torque input unit 1027 digitizes a signal corresponding to the pedal force (i.e., crank input torque) from the crank torque sensor 103 and outputs it to the calculation unit 1021. The brake input unit 1028 digitizes a signal indicating whether the brake is being applied or not from the brake sensor 107 and outputs it to the calculation unit 1021. The AD input unit 1029 digitizes the output voltage from the battery of the battery pack 101 and outputs it to the calculation unit 1021. The accelerator opening input unit 1023 digitizes a signal relating to the accelerator opening from the accelerator opening detection unit 108 and outputs the digitized signal to the calculation unit 1021 .

[0024] The calculation unit 1021 performs a predetermined calculation using inputs from the display 106 (e.g., power on / off, input for switching between assist mode and self-propelled motorcycle mode, etc.), inputs from the crank rotation input unit 1022, inputs from the accelerator opening input unit 1023, inputs from the motor rotation input unit 1024, inputs from the torque input unit 1027, inputs from the brake input unit 1028, and inputs from the AD input unit 1029, and outputs the results to the motor drive waveform generation unit 1025. The calculation unit 1021 includes a memory 10211, which stores various data used in the calculations and data in the middle of processing. Furthermore, the calculation unit 1021 may be realized by a processor executing a program, in which case the program may be recorded in the memory 10211. The memory 10211 may also be provided separately from the calculation unit 1021.

[0025] For example, the calculation unit 1021 determines, for example, the envelope voltage of a sinusoidal wave drive voltage according to the current speed (also referred to as vehicle speed) obtained from the various inputs described above and rotation information of the motor 105, and also determines the duty ratio and lead angle in PWM modulation, and outputs these to the motor drive waveform generation unit 1025. The motor drive waveform generation unit 1025 generates reference drive waveform data for each of the UVW phases according to the current phase of the motor 105, further generates drive voltage waveform data by multiplying the reference drive waveform and the envelope voltage, generates a high-frequency switching pulse train having a duty ratio according to the drive voltage waveform data, converts the switching pulse train into a gate signal having an appropriate amplitude, and outputs it to the gate of each FET in the FET bridge 1030.

[0026] In the self-propelled motorcycle mode, the calculation unit 1021 executes motor drive control mainly based on the accelerator pedal position, and in the assist mode, the calculation unit 1021 executes motor drive control mainly based on the crank input torque. In the embodiment of the present application, motor drive includes both power driving and regenerative braking.

[0027] The following describes the configuration when the technical concept of the embodiment of the present application is applied to motor drive control in the self-propelled motorcycle mode. Figure 3 shows the functional block configuration of the drive control unit realized by the calculation unit 1021.

[0028] The drive control unit according to this embodiment includes an emphasis component generating unit 3100, a smoothing unit 3200, a multiplier 3300, and an adder 3400. A drive operation amount, for example, an accelerator opening, is input to the emphasis component generating unit 3100 and the smoothing unit 3200.

[0029] The smoothing unit 3200 performs processing to remove fluctuations and noise in the input drive operation amount to make it smoother. Typically, an IIR-LPF (Infinite Impulse Response Low Pass Filter) or an FIR-LPF (Finite Impulse Response Low Pass Filter) is used.

[0030] The smoothed drive operation amount, which is the output of the smoothing unit 3200, is multiplied by a predetermined drive gain in the multiplier 3300, and is added to the emphasis component, which is the output of the emphasis component generation unit 3100, in the adder 3400 to generate the motor drive output, which is the output of the drive control unit.

[0031] The emphasized component generating section 3100 includes an increase / decrease detecting section 3110, a non-linear response section 3120, and a peak hold section 3130. The peak hold section 3130 includes a positive peak hold section 3131, a negative peak hold section 3132, and an adder 3133.

[0032] The increase / decrease detection unit 3110 extracts only the increase / decrease (also referred to as a change) in the input drive operation amount, i.e., only the increase and decrease components. The output of the increase / decrease detection unit 3110 is also referred to as the increase / decrease detection result. The increase / decrease detection unit 3110 typically uses an IIR-HPF (Infinite Impulse Response High Pass Filter), a differential filter, or a difference filter with respect to the drive operation amount at a predetermined past timing. Note that the LPF of the smoothing unit 3200 and the HPF of the increase / decrease detection unit 3110 may or may not have a conjugate relationship.

[0033] Furthermore, an increase or decrease in the drive operation amount may be detected by inputting the increase / decrease detection unit 3110 to the smoothed drive operation amount that is the output of the smoothing unit 3200. This will also be shown in an embodiment to be described later.

[0034] The nonlinear response unit 3120 outputs an appropriate nonlinear response, such as a dead band, progressive, or saturated response, in response to an increase or decrease in the drive operation amount. FIG. 4 shows an example of a nonlinear response. In FIG. 4, the vertical axis represents the nonlinear response output from the nonlinear response unit 3120, and the horizontal axis represents the increase or decrease in the drive operation amount input to the nonlinear response unit 3120. Input section A in FIG. 4 represents the dead band for an increase in the drive operation amount, and input section B represents the dead band for a decrease in the drive operation amount. The lengths of these sections may or may not be the same. This dead band is set so as not to respond to slight jerks or noise in the drive operation amount. In the example of FIG. 4, when an increase in the drive operation amount exceeding section A is detected, a nonlinear response is output along a line a1. When the increase in the drive operation amount exceeds A1, a nonlinear response is output along a line a2 whose slope is greater than line a1. When the increase in the drive operation amount exceeds A2, the nonlinear response becomes unchanged and saturates, even if the drive operation amount increases. On the other hand, when a decrease in the drive operation amount exceeding section B is detected, a nonlinear response is output along a straight line b1, and when the decrease in the drive operation amount exceeds B1, the nonlinear response becomes unchanged and saturates even if the drive operation amount decreases. In this way, the increase and decrease directions of the drive operation amount may be asymmetric. Also, the line may be a straight line like the lines a1 and a2 and the line b1, or a curve. Although an example is shown in which the slope of the line changes as the drive operation amount increases or decreases, it does not have to change. Also, the line may or may not have a saturation portion.

[0035] The peak hold unit 3130 is employed when it is preferable to extend the effect of emphasizing an increase or decrease in the drive operation amount longer than the detection period of the increase or decrease, but it does not have to be employed. The peak hold unit 3130 has a positive peak hold unit 3131 that acts on an increase in the drive operation amount and a negative peak hold unit 3132 that acts on a decrease in the drive operation amount, but their effects on the nonlinear response may be the same or different, or only one of them may be employed. The outputs of the positive peak hold unit 3131 and the negative peak hold unit 3132 are added by an adder 3133 and output to an adder 3400 as an emphasized component, which is the output of the emphasized component generation unit 3100.

[0036] When the positive peak hold unit 3131 detects a positive peak (i.e., a maximum value) of the nonlinear response, it gradually decreases the output of the positive peak hold unit 3131 from the peak toward zero. The peak may be maintained for a predetermined period and then gradually decreased from the peak toward zero. Furthermore, the positive peak hold unit 3131 may be multiplied by a predetermined gain. When the negative peak hold unit 3132 detects a negative peak (i.e., a minimum value) of the nonlinear response, it gradually increases the output of the negative peak hold unit 3132 from the peak toward zero. The peak may be maintained for a predetermined period and then gradually increased from the peak toward zero. Furthermore, the negative peak hold unit 3132 may be multiplied by a predetermined gain. Such a function of the positive peak hold unit 3131 and the negative peak hold unit 3132 is sometimes called a peak hold with time attenuation.

[0037] By employing such an emphasis component generating section 3100, it becomes possible to respond to the drive operation amount more quickly and strongly than when only the smoothing section 3200 is used.

[0038] Next, the operation of this embodiment will be described with reference to the timing chart of Fig. 5. Fig. 5(a) shows the change over time of the drive operation amount, (b) shows the change over time of the smoothed drive operation amount, (c) shows the change over time of the increase / decrease detection result that is the output of the increase / decrease detection unit 3110, (d) shows the change over time of the emphasis component that is the output of the emphasis component generation unit 3100, and (e) shows the change over time of the motor drive output. Fig. 5(c) also shows the width th1 of dead zone A and the width th2 of dead zone B that are applied to the increase / decrease detection result.

[0039] In this example, the drive operation amount is kept constant until time t1, increases from time t1 to time t2, then remains almost constant with some fluctuation, and then decreases from time t4 to time t5, after which it remains constant.

[0040] In response to such an increase or decrease in the drive operation amount, the smoothed drive operation amount increases smoothly after time t1 and is then maintained constant, as shown in FIG. 5(b), and decreases smoothly after time t4 and is then maintained constant.

[0041] 5C, the increase / decrease detection result increases sharply a little after time t1 and then remains constant, decreases sharply a little before time t2 and then remains at zero although there are fluctuations depending on the fluctuation of the drive operation amount, and decreases sharply a little after time t4 and then remains constant, increases sharply a little before time t5 and then remains at zero.

[0042] 5D, the emphasized component when the peak hold unit 3130 is not provided is represented by a solid line, and the emphasized component when the peak hold unit 3130 is provided is represented by a dotted line. Only the solid line appears in the overlapping portion.

[0043] In FIG. 5( d ), the solid lines represent the extracted portions where the increase / decrease detection result exceeds th1 and the extracted portions where it falls below th2. The dotted line c1 indicates the case where the positive peak hold unit 3131 maintains the peak value for a certain period of time and then performs a constant rate attenuation process. Therefore, the curve shows a peak value maintained until time t3 and then gradually attenuates to zero. Similarly, the dotted line d1 indicates the case where the negative peak hold unit 3132 maintains the peak value for a certain period of time and then performs a constant rate attenuation process. Therefore, the curve shows a peak value maintained until time t6 and then gradually attenuates to zero. In this example, the positive peak hold unit 3131 and the negative peak hold unit 3132 maintain the peak value for different periods of time, but they may also be the same. Furthermore, the period of time for which the peak value is maintained need not be set.

[0044] 5(e) shows the motor drive output, which is the smoothed drive operation amount x drive gain + emphasis component, with the solid line representing the motor drive output when the peak hold unit 3130 is not provided, and the dotted line representing the motor drive output when the peak hold unit 3130 is provided. Without the peak hold unit 3130, the motor drive output would have portions that change suddenly from time t1 to time t2 and from time t4 to time t5, but by providing the peak hold unit 3130, the portion of the emphasis component added by the dotted line c1 is added on top, resulting in a smooth dotted line c2, and similarly, the portion of the emphasis component added by the dotted line d1 is added on top, resulting in a smooth dotted line d2.

[0045] In this way, it is possible to remove fluctuations and noise in the drive operation amount and then add appropriate emphasis components according to increases or decreases in the drive operation amount, thereby achieving smooth motor drive output with excellent responsiveness.

[0046] In FIG. 3 , dotted lines indicate that the smoothed drive operation amount and vehicle speed may be input to the nonlinear response unit 3120. The vehicle speed is calculated, for example, based on the motor rotation input. In this embodiment, the nonlinear response of the nonlinear response unit 3120 shown in FIG. 4 is shown as an example. However, for example, the width and gain (slope of the lines a1, a2, b1, etc.) of the dead zones A and B may be changed depending on the drive operation amount itself or the smoothed drive operation amount. This makes it possible to appropriately capture the user's intention to accelerate or decelerate depending on the change in the ratio, regardless of whether the overall drive operation amount is small or large. Furthermore, the width and gain (slope of the lines a1, a2, b1, etc.) of the dead zones A and B may be changed depending on the vehicle speed. Since the drive operation amount is large when starting from zero vehicle speed and becomes smaller as the vehicle speed increases, narrowing the width of the dead zones as the vehicle speed increases can achieve an effect similar to that achieved when the width of the dead zones A and B is changed depending on the smoothed drive operation amount. Conversely, when the width of the dead zone is increased, the gain may be increased. Doing so has the effect of compensating for the average enhancement effect reduced by the dead band.

[0047] 3 shows an example in which the nonlinear response unit 3120 is provided separately from the increase / decrease detection unit 3110, but they may also be implemented as an integrated unit. For example, the increase / decrease detection unit 3110 may output a detected increase / decrease in the drive operation amount only when it detects a change that exceeds the dead band. Also, as will be described later, depending on the function of the peak hold unit 3130, the nonlinear response unit 3120 may not be provided. Furthermore, although an example in which the nonlinear response unit 3120 is provided immediately after the increase / decrease detection unit 3110 has been shown, it may be provided at a stage subsequent to the increase / decrease detection unit 3110, so it may be provided after the peak hold unit 3130, for example.

[0048] Furthermore, since there are various implementation forms for the peak hold unit 3130, an additional explanation will be provided here. Such variations of the peak hold unit 3130 are applicable not only to this embodiment but also to other embodiments described later.

[0049] As described above, the peak hold unit 3130 is employed when it is desirable to prolong the emphasis effect beyond the period during which the change in the drive operation amount is detected. However, if an IIR-HPF, for example, is employed in the increase / decrease detection unit 3110, selecting a lower cutoff frequency, i.e., a longer cutoff time constant, will result in the increase / decrease detection result becoming a sag waveform that lingers for a while, and therefore it will be possible to obtain a result similar to that of peak hold, so the employment of the peak hold unit 3130 is optional.

[0050] The peak hold unit 3130 may have the following specific configuration. For example, the simplest method is constant-rate attenuation, which attenuates at a constant rate. In this case, the signal is attenuated with a constant time constant regardless of the peak value, resulting in, for example, exponential attenuation. Alternatively, constant attenuation, which attenuates at a constant slew rate, may be used. In this case, the signal is attenuated over a period of time proportional to the peak value, so the cumulative enhancement effect becomes nonlinear enhancement proportional to the square of the peak value. Specifically, this has the effect of being less responsive to false detections due to small changes, but highly effective against clearly intentional changes. Therefore, there may be cases where it is not necessary to provide a dead zone in the nonlinear response unit 3120.

[0051] Alternatively, peak-value-dependent quantitative attenuation may be used, which attenuates at a slew rate according to the peak value when the peak is updated (i.e., when a new peak value is detected). In particular, when attenuating at a slew rate proportional to the peak value, the attenuation end time is constant regardless of the peak value. In this respect, it is similar to constant rate attenuation, but the initial attenuation ratio is smaller than that of constant rate attenuation, and conversely, the attenuation ends clearly at the end. If the slew rate is set to an arbitrary function according to the peak value, the emphasis effect can be made nonlinear.

[0052] As shown in FIG. 5D, the peak value may be maintained for a certain period of time from the point in time when the peak is updated, and then the various types of attenuation may be performed.

[0053] As described above, in FIG. 3, the increase / decrease detection unit 3110, the nonlinear response unit 3120, and the peak hold unit 3130 are shown separately in the emphasized component generation unit 3100. However, this is shown merely for the convenience of explanation, and it should be noted that there are some components that are not implemented based on the functions to be realized in the emphasized component generation unit 3100.

[0054] When the motor drive output is positive, the motor 105 performs power driving, and when it is negative, the motor 105 performs regenerative braking.

[0055] [First Modification of First Embodiment] Fig. 6 shows a functional block configuration according to this modification of the drive control unit realized by the calculation unit 1021. Components having the same functions as those in Fig. 3 are denoted by the same reference numerals.

[0056] The drive control device according to this modification includes an emphasis component generating section 3100b, a smoothing section 3200, and an adder 3400. Although the multiplier 3300 for multiplying the smoothed drive operation amount by the drive gain is not shown in Fig. 6, the multiplier 3300 may be provided in a similar manner.

[0057] As described above, the smoothing unit 3200 performs processing to remove fluctuations and noise in the input drive operation amount to make it smooth. The smoothed drive operation amount output from the smoothing unit 3200 is added to the emphasis component output from the emphasis component generation unit 3100b in the adder 3400, and a motor drive output that becomes the output of the drive control unit is generated.

[0058] The emphasized component generating section 3100 b includes a delay section 3140 , an increase detecting section 3111 , a decrease detecting section 3112 , and a peak holding section 3130 .

[0059] The delay unit 3140 delays the drive operation amount by a predetermined time and outputs it to the increase detection unit 3111 and the decrease detection unit 3112. The increase detection unit 3111 includes an adder 312, a multiplier 311, and a positive side adjustment unit 313. The multiplier 311 generates a threshold value in the increase direction by multiplying the output of the delay unit 3140, i.e., the drive operation amount from a predetermined time ago, by a first ratio Thp (also referred to as an increase ratio threshold, which employs a value greater than 1). The adder 312 also performs a calculation to subtract the threshold value in the increase direction from the current drive operation amount. The result of this calculation is output to the positive side adjustment unit 313, which applies a predetermined gain to the output of the adder 312 and performs negative value clipping processing to output the adder 312 as zero if the output is negative. Note that the predetermined gain may not be applied in some cases. The output of the positive-side adjuster 313 is output to a positive peak hold unit 3131 of the peak hold unit 3130. The positive peak hold unit 3131 is the same as in the first embodiment.

[0060] By employing such an increase detection unit 3111, the amount by which the current drive operation amount becomes equal to or greater than Thp times (>1) the drive operation amount from a predetermined time ago is output to the positive side adjustment unit 313, and if this output is a positive value, it is processed by the positive peak hold unit 3131. Here, for example, Thp=1.3.

[0061] Similarly, the decrease detection unit 3112 includes an adder 322, a multiplier 321, and a negative-side adjustment unit 323. The multiplier 321 generates a threshold value in the decrease direction by multiplying the drive operation amount from a predetermined time ago, which is the output of the delay unit 3140, by a second ratio Thn (called the decrease ratio threshold, which uses a value smaller than 1). The adder 322 also performs a calculation to subtract the threshold value in the decrease direction from the current drive operation amount. The result of this calculation is output to the negative-side adjustment unit 323, which applies a predetermined gain (which may be the same as or different from the gain of the positive-side adjustment unit 313) to the output of the adder 322 and performs positive-value clipping processing to output the output of the adder 322 as zero if the output is positive. In some cases, the predetermined gain is not applied. The output of the negative-side adjustment unit 323 is output to a negative peak hold unit 3132 of the peak hold unit 3130. The negative peak hold unit 3132 is the same as in the first embodiment.

[0062] By employing such a decrease detection unit 3112, the amount by which the current drive operation amount becomes equal to or less than Thn times (<1) the drive operation amount from a predetermined time ago is output to the negative side adjustment unit 323, and if this output is a negative value, it is processed by the negative peak hold unit 3132. Here, for example, Thn=0.6.

[0063] Furthermore, as an additional process in the positive side adjustment unit 313, when the output from the adder 312 is positive, a predetermined gain may be applied, and then the output may not be output as is, but may be limited to a value equal to or less than a third ratio Lempp (>0) times the current driving operation amount or smoothing driving operation amount. Similarly, when the output from the adder 322 is negative, the negative side adjustment unit 323 may also limit the output to a value equal to or greater than a fourth ratio Lempn (<0) times the current driving operation amount or smoothing driving operation amount, but may be output as is, but may be output as is. In this way, the upper and lower limits of the emphasized component can be limited relatively to the magnitude of the current driving operation amount, etc., and over-emphasis due to changes in the driving operation amount can be prevented. The same applies to the positive side adjustment units (e.g., 313, 5130, 5170, 623) and negative side adjustment units (e.g., 323, 5230, 5270, 643) in the embodiments described below.

[0064] In this modification, in order to obtain an effect similar to that in the first embodiment in which the width of the dead band is made proportional to, for example, the smoothed drive operation amount, it is possible to extract the amount of change that is equal to or greater than a predetermined ratio, rather than a predetermined difference from the past drive operation amount. Specifically, as described above, an increase or decrease is detected by comparing the drive operation amount delayed by delay unit 3140 (i.e., the drive operation amount a predetermined time ago) multiplied by a predetermined ratio (Thp and Thn) with the current drive operation amount.

[0065] In the example described above, the width of the dead band is 1.3 times on the positive side and 0.6 times on the negative side, so that the width is asymmetrical between positive and negative. The gains provided by the positive-side adjustment unit 313 and the negative-side adjustment unit 323 may be gains proportional to the input, or may be gains represented by some kind of curve. A saturation portion may be provided as shown in FIG. 4 . Furthermore, the gains and saturation portions of the positive-side adjustment unit 313 and the negative-side adjustment unit 323 may be asymmetrical between positive and negative.

[0066] The timing chart in this modified example is similar to that shown in Fig. 5. However, although not shown in Fig. 5, the width of the dead zone is not fixed but is created by a predetermined ratio (i.e., Thp and Thn), so whether the drive operation amount is large or small overall, if there is a change of a predetermined ratio or more, it is detected as an intention to accelerate or decelerate.

[0067] As described above, in the first embodiment, a dead band of a predetermined amount is provided, and in the first modification of the first embodiment, a dead band of a predetermined ratio is provided, but both may be used in combination. By using both, it is possible to prevent an unnecessary increase or decrease from being detected due to slight variations in the input operation amount when the input operation amount is very small, which would be the case with only a dead band of a predetermined ratio. Specifically, a nonlinear response unit having a dead band characteristic of a predetermined amount may be added immediately before or after the delay unit 3140 in FIG. 6.

[0068] Alternatively, a predetermined positive offset (i.e., correction value) may be added to the right input or left output of the multiplier 311 in the increase detection unit 3111 in FIG. 6, or a predetermined negative offset may be added to the left input or lower output of the adder 312, thereby adding a predetermined amount of increase-side dead band characteristic, and similar processing may be performed with the opposite polarity for the decrease detection unit.

[0069] [Embodiment 2] In an electrically assisted bicycle, which is a type of electric vehicle, the crank input torque generated by the pedaling force directly drives the rear wheel via a mechanical transmission mechanism such as a chain, and is also used as the driving operation amount for the assist drive by the motor 105. In other words, when switched to the assist mode, the crank input torque is used as the driving operation amount.

[0070] Like the crank input torque, the torque due to pedaling force becomes nearly zero at the top and bottom dead centers of the crank due to the alternating pedaling force of the left and right legs, and becomes a ripple torque with a half-rotation period that peaks when the crank is nearly horizontal. To avoid interpreting increases and decreases in this ripple itself as increases and decreases in the input driving force, it is preferable to align the ripple phase with the crank rotation and make comparisons.

[0071] Taking this into consideration, the drive control unit according to this embodiment has the configuration shown in Fig. 7. Note that components having the same functions as those in the first embodiment are given the same reference numerals.

[0072] The drive control section according to this embodiment has an emphasized component generating section 4100, a torque smoothing section 4200, an adder 4300, and a multiplier 4400. The crank input torque is input to the emphasized component generating section 4100 and the torque smoothing section 4200.

[0073] The torque smoothing unit 4200 performs a smoothing process to smooth the ripple of the crank input torque, for example. This process is also disclosed in Patent Document 1, so a detailed description thereof will be omitted.

[0074] The smoothed crank input torque, which is the output of the torque smoothing unit 4200, is added to the emphasized component, which is the output of the emphasized component generation unit 4100, in an adder 4300, and is further multiplied by a predetermined assist ratio in a multiplier 4400 to generate a motor drive output, which is the output of the drive control unit.

[0075] The emphasized component generating section 4100 includes an increase / decrease detecting section 4110 , a nonlinear response section 3120 , and a peak hold section 3130 .

[0076] The increase / decrease detection unit 4110 includes a half-rotation delay unit 4111 and an adder 4112. The half-rotation delay unit 4111 is, for example, a shift register, and is a 32-stage shift register when a 32-pulse shift clock is generated per half crank rotation from the Hall signal output from the motor 105 by the motor rotation input unit 1024, etc. That is, the crank input torque is input to tap T0 of the 32-stage shift register, and after 32 clocks equivalent to a half crank rotation, the crank input torque delayed by a half crank rotation (i.e., the crank input torque before a half crank rotation) is output from tap T32.

[0077] Adder 4112 subtracts the crank input torque half a crank rotation ago from the current crank input torque, and outputs the calculation result (i.e., the increase / decrease detection result) to nonlinear response unit 3120. In this way, the crank input torque one ripple cycle ago is compared with the crank input torque that is in phase with the crank input torque, so that increase / decrease in the crank input torque can be detected without being affected by the ripple.

[0078] The non-linear response unit 3120 and peak hold unit 3130 have the same functions as those in the first embodiment.

[0079] As described in the first embodiment, the nonlinear response unit 3120 may receive the smoothed crank input torque or vehicle speed, which is the output of the torque smoothing unit 4200. Alternatively, the output of the half-rotation delay unit 4111 or the crank rotation speed may be input. For example, the width of the dead band for increases or decreases in crank input torque may be changed depending on the smoothed crank input torque, the output of the half-rotation delay unit 4111, or the crank input torque. For example, the width of the dead band may be changed so that increases or decreases in crank input torque are detected at a substantially constant rate, regardless of whether the crank input torque is generally small or large. Furthermore, when the width of the dead band is changed depending on the vehicle speed or crank rotation speed, the rate of change is particularly large when the crank input torque is large during start-up, so the width of the dead band may be widened at low speeds.

[0080] The operation of this embodiment will be described with reference to the timing chart of Fig. 8. Fig. 8(a) shows the time changes in the crank input torque (solid line) and the smoothed crank input torque (dotted line), Fig. 8(b) shows the time changes in the crank input torque before a half crank rotation which is the output of the half-rotation delay unit 4111, Fig. 8(c) shows the time changes in the increase / decrease detection result which is the output of the increase / decrease detection unit 4110, Fig. 8(d) shows the time changes in the emphasized component which is the output of the emphasized component generation unit 3100, and Fig. 8(e) shows the time changes in the motor drive output. Fig. 8(c) also shows the width th1 of dead zone A and the width th2 of dead zone B which are applied to the increase / decrease detection result.

[0081] In the example of FIG. 8 , the crank input torque one ripple prior ( FIG. 8( b) ), which corresponds to a half-turn of the crank, is compared with the current crank input torque ( FIG. 8( a) ). Therefore, increases and decreases in the crank input torque, i.e., increases and decreases in the crank input torque, are detected at the portions indicated by arrows C and D. That is, as shown in FIG. 8( c) , an increase in the crank input torque is detected just before time t11, and the torque exceeds th1 at time t11. Also, a decrease in the crank input torque is detected just before time t12, and the torque falls below th2 at time t12. Therefore, as shown in FIG. 8( d) , the emphasized component rises from time t11, peaks, and then decays at a constant rate. Then, from time t12, it falls, peaks, and then decays at a constant rate. Therefore, as shown in FIG. 8( e) , the motor drive output is the sum of the smoothed crank input torque indicated by the dotted line in FIG. 8( a) and the emphasized component indicated by the dotted line in FIG. 8( d) .

[0082] By performing the above-described processing, when a pedal input torque having ripples is used as a driving operation amount, it becomes possible to appropriately add an emphasis component according to the increase or decrease in the pedal input torque.

[0083] Although an example has been shown in which the output of the torque smoothing unit 4200 and the output of the emphasis component generating unit 4100 are added together and then multiplied by the assist ratio, it is also possible to multiply the output of the torque smoothing unit 4200 by a first coefficient and the output of the emphasis component generating unit 4100 by a second coefficient before adding them together.

[0084] Furthermore, although the case where 32 pulses of the shift clock are generated per half crank rotation has been described, 32 pulses is just an example, and other numbers of pulses may be used.

[0085] [First Modification of Second Embodiment] The configuration shown in FIG. 7 can be modified to be equivalent to the configuration shown in FIG. 9, for example.

[0086] The drive control unit according to this modification includes a 31-stage shift register 4500, a moving average unit 4600, an emphasis component generation unit 4100b, an adder 4300, and a multiplier 4400. Components having the same functions as those in the first and second embodiments are denoted by the same reference numerals. In this modification, a case will be described in which a 32-pulse shift clock is generated per half crank rotation.

[0087] In this modified example, a torque smoothing unit is configured using a 31-stage shift register 4500 and a moving average unit 4600. In order to smooth the motor drive output and eliminate ripples to maximize drive efficiency, crank input torque is often generated by smoothing it. The configuration of this modified example is adopted in particular to generate a flat assist torque with relatively little response delay and complete ripple removal.

[0088] Specifically, when the crank input torque is sequentially input to the 31-stage shift register 4500, the crank input torque delayed by one shift clock, two shift clocks, ... 31 shift clocks is output from each tap of the 31-stage shift register 4500. Since the moving average unit 4600 receives the crank input torque delayed by one to 31 shift clocks in addition to the current crank input torque, it outputs the average of these (= total input / 32). This provides a smoothed crank input torque. Details are described in Patent Document 1, and further description will be omitted here.

[0089] This smoothed crank input torque is added to the emphasized component, which is the output of the emphasized component generating unit 4100b, in an adder 4300, and further multiplied by a predetermined assist ratio in a multiplier 4400 to generate the motor drive output, which is the output of the drive control unit.

[0090] The emphasized component generating unit 4100b has an increase / decrease detecting unit 4110b, a nonlinear response unit 3120, and a peak hold unit 3130. The increase / decrease detecting unit 4110b has a delay unit 4115 that delays the smoothed crank input torque by, for example, one shift clock, an adder 4116 that subtracts the output of the delay unit 4115 from the smoothed crank input torque, and a multiplier 4117 that multiplies the output of the adder 4116 by 32. The output of the multiplier 4117 is output to the nonlinear response unit 3120 as the increase / decrease detection result. Note that the delay of the delay unit 4115 may be several shift clocks instead of one shift clock.

[0091] The non-linear response unit 3120 and peak hold unit 3130 are the same as those in the first embodiment, and therefore a description thereof will be omitted here.

[0092] In the second embodiment, the increase / decrease detection unit 4110 simply used the difference between the current crank input torque (the value of tap T0 (abbreviated as T0, and the same applies to the values ​​of the other taps)) and the crank input torque 32 shift clocks earlier (T32) as the increase / decrease detection result.

[0093] In this modification, the delay unit 4115 and adder 4116 perform the following calculation: (T0+T1+...T30+T31) / 32 - (T0+T1+...T30+T31) / 32 x [1 / Z] ([1 / Z] is one shift clock delay) = (T0+T1+...T30+T31) / 32 - (T1+T2+...T31+T32) / 32 = (T0-T32) / 32

[0094] Therefore, by multiplying by 32 in the multiplier 4117, (T0-T32) is obtained, and it can be seen that an operation equivalent to that in the second embodiment is performed.

[0095] Since the processing equivalent to that of the second embodiment is performed overall, a timing chart similar to that of the second embodiment can be obtained, and similar effects can be obtained.

[0096] This modification can also be said to be an example in which the input of the increase / decrease detection unit is the smoothed drive operation amount, which is the output of the smoothing unit.

[0097] [Second Modification of Second Embodiment] The technical elements in the first modification of the first embodiment can also be introduced into the second embodiment.

[0098] An example of the configuration in this case is shown in Figure 10. Components having the same functions as those in the first and second embodiments are given the same reference numerals. Also in this modification, a case where a shift clock of 32 pulses is generated per half crank rotation will be described.

[0099] The drive control unit in this modification includes a torque smoothing unit 4200, an emphasis component generating unit 4100c, an adder 4300, and a multiplier 4400.

[0100] The crank input torque is input to the emphasized component generating section 4100c and the torque smoothing section 4200. The torque smoothing section 4200 performs a smoothing process on the crank input torque to generate a smoothed crank input torque.

[0101] As described in Patent Document 1, the torque smoothing unit 4200 may mix the smoothed crank input torque and the crank input torque in any ratio of positive and negative polarities to generate a smoothed crank input torque with residual ripple or a smoothed crank input torque with a ripple component of opposite polarity. This is the same in the second embodiment and its modified example.

[0102] This smoothed crank input torque is added to the emphasized component, which is the output of the emphasized component generating section 4100c, by an adder 4300, and further multiplied by a predetermined assist ratio by a multiplier 4400 to generate a motor drive output, which is the output of the drive control section. In the example of Fig. 10, the smoothed crank input torque and the emphasized component are added together and then multiplied by the assist ratio, but it is also possible to multiply only the smoothed crank input torque by the assist ratio and then add the emphasized component to that output. Alternatively, it is also possible to multiply only the smoothed crank input torque by the first assist ratio, and multiply the emphasized component by the second assist ratio, and then add the respective outputs.

[0103] The emphasized component generator 4100c in this modification is similar to the emphasized component generator 3100b shown in Fig. 6, except that a half-rotation delay unit 4111 is used instead of the delay unit 3140. That is, the crank input torque input to the increase detector 3111 and the decrease detector 3112 is delayed by 32 shift clocks, which corresponds to a half crank rotation, rather than being delayed by one sample.

[0104] The first ratio Thp (also called the increase ratio threshold, a value greater than 1) that defines the width of the dead zone in the increase detection unit 3111 is, for example, 1.3, as in Modification 1 of the first embodiment. The second ratio Thn (also called the decrease ratio threshold, a value smaller than 1) that defines the width of the dead zone in the decrease detection unit 3112 is, for example, 0.6, as in Modification 1 of the first embodiment.

[0105] In this way, a threshold value is generated by multiplying the crank input torque half a crank rotation ago by the first ratio Thp, and the threshold value is compared with the current crank input torque to detect an increase in the crank input torque. A threshold value is generated by multiplying the crank input torque half a crank rotation ago by the second ratio Thn, and the threshold value is compared with the current crank input torque to detect a decrease in the crank input torque.

[0106] In this way, since detection is based on a ratio rather than a difference from the past, an increase or decrease can be detected based on the same ratio overall when a large crank input torque is input and when a small crank input torque is input, and problems such as a false detection due to a slight change when a large crank input torque is input or a failure to detect a large ratio change when a small crank input torque is input are less likely to occur.

[0107] A timing chart for this modification is shown in Fig. 11. In Fig. 11, (a) shows the changes over time in the crank input torque (solid line) and the smoothed crank input torque (dotted line), (b) shows the changes over time in the crank input torque before a half crank rotation which is the output of the half-rotation delay unit 4111, (c) shows the changes over time in the detected increase in crank input torque, (d) shows the changes over time in the detected decrease in crank input torque, (e) shows the changes over time in the emphasized component which is the output of the emphasized component generation unit 4100c, and (f) shows the changes over time in the motor drive output.

[0108] In the example of FIG. 11 , the crank input torque one ripple before ( FIG. 11( b) ), which corresponds to half a crank rotation, is compared with the current crank input torque ( FIG. 11( a) ). Therefore, increases and decreases in the crank input torque, i.e., increases and decreases in the crank input torque, are detected at the portions indicated by arrows E and F (see FIGS. 11( c) and 11(d) ). That is, at time t13, the threshold value obtained by multiplying the crank input torque half a crank rotation ago by Thp is exceeded. At time t14, the threshold value obtained by multiplying the crank input torque half a crank rotation ago by Thn is exceeded. Therefore, as shown in FIG. 11( e) , the emphasized component rises from time t13, peaks, and then decays at a constant rate. Then, from time t14, the emphasized component falls, peaks, and then decays at a constant rate. Therefore, as shown in FIG. 11( f) , the motor drive output is the sum of the smoothed crank input torque indicated by the dotted line in FIG. 11( a) and the emphasized component indicated by FIG. 11( e) .

[0109] By carrying out the above-described processing, when a pedal input torque having ripples is adopted as a driving operation amount, it becomes possible to appropriately add an emphasis component according to the increase or decrease of the pedal input torque.

[0110] In the second embodiment, when the dead bands A and B are fixed, even if the crank input torque changes at the same rate when the crank input torque is generally large and when it is generally small, the increase / decrease detection unit 4110 is more likely to detect an increase / decrease when the crank input torque is generally large, making it easier to erroneously detect an intention to accelerate or decelerate. This is particularly noticeable when starting off. Figure 12 illustrates this situation. Figure 12(a) shows the time changes in the crank input torque (solid line) and the smoothed crank input torque (dotted line), (b) shows the time changes in the crank input torque before half a crank rotation, (c) shows the time changes in the increase / decrease detection result output by the increase / decrease detection unit 4110, (d) shows the time changes in the emphasized component output by the emphasized component generation unit 3100, and (e) shows the time changes in the motor drive output. Figure 12(c) also shows the width th1 of the dead band A and the width th2 of the dead band B applied to the increase / decrease detection result. Since this is the start of the vehicle, the time for half a crank rotation is gradually shortened, and the time for half a crank rotation of the crank input torque half a crank rotation ago is longer than the time for half a crank rotation of the current crank input torque. Therefore, in Figure 12(b), the crank input torque half a crank rotation ago is shown shortened in time to match the time for half a crank rotation of the crank input torque for comparison. This is also the case in Figure 13.

[0111] As shown in Figure 12(a), a very large crank input torque is input when the vehicle starts moving. However, even during acceleration, the amplitude of the crank input torque gradually decreases with each half-turn of the crank as the vehicle speed increases. In this situation, the vehicle is still accelerating, and the decrease in crank input torque is not large. However, since the increase / decrease detection unit 4110 simply monitors the difference, as shown by the solid line in Figure 12(c), a decrease in crank input torque is detected after time tx, and some portions exceed the width th2 of the dead zone B. In other words, the vehicle is erroneously recognized as having an intention to decelerate after time tx. Therefore, a little after time tx, the emphasized component shown in Figure 12(d) suddenly decreases from the portion where the increase / decrease detection result exceeds the width th2 of the dead zone B, resulting in a weakened acceleration.

[0112] On the other hand, in this modified example, a first ratio Thp and a second ratio Thn are set, and an increase or decrease in crank input torque is detected when the torque increases above the first ratio Thp or decreases below the second ratio Thn, thereby solving the above-mentioned problems in the second embodiment.

[0113] This will be explained using Figure 13. Figure 13(a) is the same as Figure 12(a), and Figure 13(b) is the same as Figure 12(b), and shows, for example, time changes in crank input torque (solid line) and smoothed crank input torque (dotted line) at start-up, as well as time changes in crank input torque before half a crank rotation. Figure 13(c) shows time changes in the increase detection result output by the increase detector 3111, Figure 13(d) shows time changes in the emphasized component output by the emphasized component generator 4100c, and Figure 13(e) shows time changes in the motor drive output.

[0114] As shown in Figure 13(c), up to time tx, the increase detection unit 3111 detects an increase in the crank input torque, similar to the output of the increase / decrease detection unit 4110 in the second embodiment. However, after time tx, no increase in the crank input torque is detected. In this modification, even if the crank input torque itself decreases, the decrease detection unit 3112 does not consider it to be a decrease unless it is equal to or less than the crank input torque one half crank rotation ago multiplied by the second ratio Thn. Therefore, the output of the decrease detection unit 3112 remains zero both before and after time tx. Therefore, as shown in Figure 13(d), the emphasized component is limited to the initially detected increase, and the abrupt decrease in the emphasized component that occurred after time tx does not occur. As a result, as shown in Figure 13(e), the motor drive output also follows a substantially smooth curve generated by the smoothed crank input torque and the emphasized component.

[0115] In this way, this modified example can appropriately reflect the user's intention to accelerate or decelerate with a simpler configuration than the second embodiment in which the widths A and B of the dead zones are fixed.

[0116] [Embodiment 3] A problem common to the second embodiment and its variants 1 and 2 is that, as shown in Figures 9 and 11, there is no problem when pedaling with equal left and right pedaling force. However, since there is often a difference in left and right leg strength, the crank input torque may show fluctuations in strength every half crank rotation, i.e., there is often a ripple component with a one-rotation period. Although there are individual differences, the peak ratio of the ripple torque may reach a maximum of 1.2 to 1.3 times. This is shown in the timing chart of Figure 14.

[0117] 14A shows the time changes in the crank input torque (solid line) and the smoothed crank input torque (dotted line), (b) shows the time changes in the crank input torque before half a crank rotation, (c) shows the time changes in the emphasized component, and (d) shows the time changes in the motor drive output. That is, FIG. 14 corresponds to FIG. 11.

[0118] As can be seen from Figure 14(a), the crank input torque exhibits a different amplitude for every other ripple, whether before, during, or after power increase. Therefore, ripples also appear in the smoothed crank input torque. Furthermore, not only are increases and decreases in crank input torque (i.e., increases and decreases) detected at the portions indicated by arrows G and H, but the difference in left and right leg force is also reflected in the difference between the crank input torque half a crank rotation ago and the current crank input torque, resulting in erroneous detection of even minute changes, such as those indicated by J through O in Figure 14(c). Therefore, compared to Figure 11(d), the motor drive output in Figure 14(d) also reflects erroneous detection results.

[0119] For this reason, it is possible to consider modifying the parameters for detecting increases and decreases in crank input torque so that they have a margin of error compared to their original values. However, if the margin is too large, there is a risk that the increases and decreases that should be detected will not be detected.

[0120] Therefore, to eliminate the influence of the difference in left and right leg strength, a configuration is adopted in which the current crank input torque is compared with the crank input torque one crank rotation ago, rather than half a crank rotation ago. This makes it possible to detect increases and decreases in the crank input torque between the left leg and the right leg, and to accurately grasp the intended increase or decrease in the crank input torque without being influenced by the difference in left and right leg strength.

[0121] An example of a configuration for this purpose is shown in Fig. 15. Components having the same functions in the first and second embodiments and their modifications are given the same reference numerals. Also in this embodiment, a case where a 32-pulse shift clock is generated per half crank rotation will be described.

[0122] As can be seen by comparing FIG. 15 with FIG. 10, an emphasis component generator 4100d is used instead of the emphasis component generator 4100c, and what differs from emphasis component generator 4100d is that a one-rotation delay unit 4113 is used instead of the half-rotation delay unit 4111.

[0123] The one-rotation delay unit 4113 is configured with a shift register that delays the crank input torque by one crank rotation, that is, by 64 shift clocks, so that output is performed from the 64th tap T64.

[0124] The first ratio Thp defining the width of the dead zone in the increase detection unit 3111 is, for example, 1.15, which is different from that in Modification 1 of the first embodiment, etc. The second ratio Thn defining the width of the dead zone in the decrease detection unit 3112 is, for example, 0.7, which is different from that in Modification 1 of the first embodiment, etc. This is because, when comparing with the crank input torque before half a crank rotation, the width of the dead zone (also called the ratio to the crank input torque) is set large enough to allow for a margin in consideration of the influence of the difference in left and right leg strength. However, when comparing with the crank input torque before one crank rotation, the width of the dead zone does not need to be so large.

[0125] Next, a timing chart of this embodiment is shown in Fig. 16. In Fig. 16, (a) shows the time changes in the crank input torque (solid line) and the smoothed crank input torque (dotted line), (b) shows the time changes in the crank input torque one crank rotation ago which is the output of one-rotation delay section 4113, (c) shows the time changes in the emphasized component which is the output of emphasized component generation section 4100d, and (d) shows the time changes in the motor drive output.

[0126] In the example of FIG. 16 , the crank input torque ( FIG. 16( b) ) two ripples ago, equivalent to one crank rotation, is compared with the current crank input torque ( FIG. 16( a) ). Therefore, as indicated by arrows P1 and P2, the crank input torques of the left and right legs are compared, and an increase in the crank input torque, i.e., an increase in the crank input torque, is detected. That is, around time t21, an increase in the crank input torque is detected, and for one leg, the torque exceeds a threshold value obtained by multiplying the crank input torque of the previous crank rotation by Thp. Thereafter, the torque for the other leg also exceeds a threshold value obtained by multiplying the crank input torque of the previous crank rotation by Thp. Therefore, as shown in FIG. 16( c) , two peaks appear as the emphasized component after time t21. Between the two peaks and after the second peak, a constant-rate decay curve is drawn.

[0127] Furthermore, as indicated by arrows Q1 and Q2, the crank input torques of the left and right legs are compared, and a decrease in the crank input torque, i.e., a reduction in force, is detected. That is, around time t22, a decrease in the crank input torque is detected, and the crank input torque for one leg falls below a threshold value obtained by multiplying the crank input torque from one crank rotation ago by Thn. Thereafter, the crank input torque for the other leg also falls below a threshold value obtained by multiplying the crank input torque from one crank rotation ago by Thn. Therefore, as shown in FIG. 16(c), two peaks appear as the emphasized component after time t22. Note that a constant-rate decay curve is drawn between the two peaks and after the second peak.

[0128] Therefore, as shown in Figure 16(d), the motor drive output is the sum of the smoothed crank input torque, which has a small ripple indicated by the dotted line in Figure 16(a), and the emphasized component shown in Figure 16(c). The motor drive output fluctuates slightly due to the ripple contained in the smoothed crank input torque, but it can be seen that the motor drive output is smooth, with an emphasized component that includes two peaks when the force is increased and another that includes two peaks when the force is decreased.

[0129] By adopting such a configuration, it is possible to suppress erroneous detection of force increase or decrease due to the influence of the difference in left and right leg strength.

[0130] [Variation 1 of Embodiment 3] In the third embodiment, even if there is a difference in pedal force between the left and right, the intention to accelerate or decelerate can be detected quickly and appropriately. However, there is a problem in that it cannot respond immediately if, for example, the increase or decrease in crank input torque is intentionally changed and then immediately changed in the opposite direction after half a crank rotation.

[0131] Therefore, in order to address the above problem, in addition to comparing the crank input torque with the crank input torque one crank rotation ago, a comparison with the crank input torque half a crank rotation ago is also performed. Here, an example is shown in which the third embodiment (FIG. 15) and Modification 2 of the second embodiment (FIG. 10) are integrated.

[0132] An example of the configuration of the drive control unit according to this modified example is shown in Fig. 17. Note that components having the same functions as those described above are given the same reference numerals. Also in this embodiment, a case where a 32-pulse shift clock is generated per half crank rotation will be described.

[0133] The drive control unit according to this modification includes a torque smoothing unit 4200 , an emphasized component generating unit 5000 , an adder 4300 , and a multiplier 4400 .

[0134] The crank input torque is input to the emphasized component generating section 5000 and the torque smoothing section 4200. The torque smoothing section 4200 performs a smoothing process on the crank input torque to generate a smoothed crank input torque.

[0135] This smoothed crank input torque is added to the emphasis component, which is the output of the emphasis component generation unit 5000, in the adder 4300, and then multiplied by a predetermined assist ratio in the multiplier 4400 to generate the motor drive output, which is the output of the drive control unit.

[0136] The emphasized component generating unit 5000 includes a one-rotation delay unit 4113 , an increase processing unit 5100 , a decrease processing unit 5200 , and an adder 5300 .

[0137] The one-rotation delay unit 4113 is configured with a shift register that delays the crank input torque by one crank rotation, i.e., 64 shift clocks. However, not only is the crank input torque delayed by one crank rotation output from tap T64, but also the crank input torque delayed by half a crank rotation is output from tap T32.

[0138] The increase processing unit 5100 detects and combines the increase in crank input torque per half crank rotation and the increase in crank input torque per one crank rotation, and performs peak hold processing to generate an emphasized component for the increase. The decrease processing unit 5200 detects and combines the decrease in crank input torque per half crank rotation and the decrease in crank input torque per one crank rotation, and performs peak hold processing to generate an emphasized component for the decrease. The adder 5300 adds the output of the increase processing unit 5100 and the output of the decrease processing unit 5200 to generate an emphasized component, which is the output of the emphasized component generating unit 5000. Note that instead of simple addition, weighted addition, an operation that selects the one with the larger absolute value, or another operation for combination may be used.

[0139] The increase processing unit 5100 has an adder 5110 , a multiplier 5120 , a first positive-side adjustment unit 5130 , a first synthesis unit 5140 , a multiplier 5150 , an adder 5160 , and a positive peak hold unit 3131 .

[0140] Multiplier 5120 generates a threshold value in the increasing direction for a half crank rotation by multiplying the crank input torque from one-rotation delay unit 4113 by first ratio Thp1 (which adopts a value greater than 1). Adder 5110 subtracts the threshold value in the increasing direction for a half crank rotation from the current crank input torque. The result of this calculation is output to first positive side adjuster 5130, which applies a predetermined gain to the output of adder 5110 and performs negative value clipping processing to output the output of adder 5110 as zero if the output is negative. Note that the predetermined gain may not be applied. The output of first positive side adjuster 5130 is output to first combiner 5140.

[0141] Meanwhile, multiplier 5150 generates a threshold value in the increasing direction for one crank rotation by multiplying the crank input torque from one rotation delay unit 4113 by second ratio Thp2 (which adopts a value greater than 1). Adder 5160 subtracts the threshold value in the increasing direction for one crank rotation from the current crank input torque. The result of this calculation is output to second positive side adjuster 5170, which applies a predetermined gain to the output of adder 5160 and performs negative value clipping processing, outputting the output of adder 5160 as zero if the output is negative. Note that the predetermined gain may not be applied. The output of second positive side adjuster 5170 is also output to first combiner 5140.

[0142] First combiner 5140, for example, adds or weights the output of first positive side adjuster 5130 and the output of second positive side adjuster 5170, and outputs the result to positive peak hold unit 3131. Positive peak hold unit 3131 executes predetermined peak hold processing as described above, and outputs the result to adder 5300. The calculation of first combiner 5140 may be a calculation for another combination.

[0143] The decrease processing unit 5200 also includes an adder 5210 , a multiplier 5220 , a first negative-side adjustment unit 5230 , a second synthesis unit 5240 , a multiplier 5250 , an adder 5260 , and a negative peak hold unit 3132 .

[0144] The multiplier 5220 generates a threshold value in the decreasing direction for a half crank rotation by multiplying the crank input torque from the one-rotation delay unit 4113 by a first ratio Thn1 (which uses a value smaller than 1). The adder 5210 subtracts the threshold value in the decreasing direction for a half crank rotation from the current crank input torque. The result of this calculation is output to the first negative adjustment unit 5230, which applies a predetermined gain to the output of the adder 5210 and performs positive value clipping to output the output of the adder 5210 as zero if the output is positive. Note that the predetermined gain may not be applied. The output of the first negative adjustment unit 5230 is output to the second synthesis unit 5240.

[0145] Meanwhile, multiplier 5250 generates a threshold value in the decreasing direction for one crank rotation by multiplying the crank input torque from one rotation delay unit 4113 by second ratio Thn2 (which uses a value smaller than 1). Adder 5260 subtracts the threshold value in the decreasing direction for one crank rotation from the current crank input torque. The result of this calculation is output to second negative side adjuster 5270, which applies a predetermined gain to the output of adder 5260 and performs positive value clipping processing to output the output of adder 5260 as zero if the output is negative. Note that the predetermined gain may not be applied. The output of second negative side adjuster 5270 is also output to second combiner 5240.

[0146] The second combiner 5240 adds or weights the output of the first negative-side adjuster 5230 and the output of the second negative-side adjuster 5270, for example, and outputs the result to the negative peak hold unit 3132. The negative peak hold unit 3132 executes a predetermined peak hold process as described above, and outputs the result to the adder 5300. The calculation of the second combiner 5240 may be a calculation for another combination.

[0147] Since there is a difference in leg strength between the left and right legs, different values ​​are used for the first ratio Thp1 per half crank rotation and the second ratio Thp2 per one crank rotation, and similarly, different values ​​are used for the first ratio Thn1 per half crank rotation and the second ratio Thn2 per one crank rotation, thereby making the ratio widths of the dead zones different.

[0148] For example, values ​​such as Thp1 = 1.3, Thp2 = 1.15, Thn1 = 0.6, and Thn2 = 0.7 are used. In this example, a dead zone is set for one crank rotation, with no response from +15% to -30%, and a dead zone is set for a half crank rotation, with no response from +30% to -40%. These values ​​are just an example, but by widening the dead zone ratio for a half crank rotation, the influence of the difference in left and right leg strength is suppressed. Instead, it is preferable to optimize the balance between the two, for example, by increasing the weight or gain (i.e., the gradient of output relative to input) for a half crank rotation.

[0149] With this configuration, an emphasis component based on a comparison with a half crank rotation ago and an emphasis component based on a comparison with a full crank rotation ago are combined, making it possible to obtain a rapid response that takes into account not only pedal force changes over one crank rotation but also pedal force changes over a half crank rotation.

[0150] Fig. 18 is a timing chart showing an example of the operation of the drive control unit according to the third embodiment. Fig. 18(a) shows the time changes in the crank input torque (solid line) and the smoothed crank input torque (dotted line), Fig. 18(b) shows the time changes in the crank input torque one crank rotation before, Fig. 18(c) shows the time changes in the emphasized component, and Fig. 18(d) shows the time changes in the motor drive output.

[0151] As shown in Figure 18(a), an increase in pedal force occurs from the ripple R of the crank input torque, which is reflected in the emphasis component and motor drive output as shown in Figures 18(c) and 18(d), similar to what is shown in Figure 16.

[0152] On the other hand, as shown by the ripples S and T of the crank input torque, one leg is initially reduced, and then the other leg is immediately increased again. When this type of crank input occurs, the reduction in torque is detected in response to the ripple S and reflected in the emphasis component and the motor drive output. However, since the ripple T remains almost unchanged from the crank input torque one crank rotation earlier, the increase in torque is not detected. In other words, at time tr, the peak-hold attenuation due to the reduction in torque detected in the previous ripple S appears, resulting in smooth changes in both the emphasis component and the motor drive output. However, after another half crank rotation, the comparison indicated by the arrow U detects a second increase in torque, and a positive peak appears in the emphasis component, as shown in FIG. 18(c). In other words, a delay occurs in detecting the half crank rotation.

[0153] Meanwhile, a timing chart showing an example of the operation of the drive control unit according to this modification is shown in Fig. 19. In Fig. 19, (a) shows the time changes in the crank input torque (solid line) and the smoothed crank input torque (dotted line), (b) shows the time changes in the crank input torque half a crank rotation ago, (c) shows the time changes in the crank input torque one crank rotation ago, (d) shows the time changes in the emphasized component, and (e) shows the time changes in the motor drive output.

[0154] 19(a) and 19(c) are the same as FIGS. 18(a) and 18(b), but in this modification, the ripple T of the crank input torque, which indicates a second boost, is compared with the ripple of the crank input torque half a turn before the crank, as indicated by the arrow V. Therefore, at time tr, when the ripple peaks, the emphasized component also peaks as shown in FIG. 19(d), and then follows a decaying curve, and this result is also reflected in the motor drive output as shown in FIG. 19(e). In other words, it can be seen that the response speed is improved compared to the third embodiment.

[0155] [Fourth Embodiment] In the second and third embodiments, the crank input torque is used as the input to the emphasis component generation unit, but with an electrically assisted bicycle, the user may rotate the crank quickly so that the pedaling force is detected by the crank torque sensor 103, or may rotate the crank slowly so that the pedaling force is not detected by the crank torque sensor 103. There may also be an action to increase the crank rotation speed in order to transmit the pedaling force to the crank torque sensor 103 from a state in which the pedaling force is not detected by the crank torque sensor 103, or conversely, an action to decrease the crank rotation speed in a state in which the pedaling force is detected by the crank torque sensor 103. In this way, crank rotation can also be used as a parameter representing the user's intention.

[0156] In this embodiment, a case will be described in which a value related to or corresponding to the crank rotation speed is used in addition to the crank input torque as a parameter (also called a second drive operation amount) that represents the user's intention and is reflected in the emphasis component.

[0157] An example of the configuration of the drive control unit according to this embodiment is shown in Fig. 20. Components having the same functions as those described above are given the same reference numerals. Also in this embodiment, a case where a 32-pulse shift clock is generated per half crank rotation will be described.

[0158] The drive control unit according to this embodiment includes a torque smoothing unit 4200 , an emphasized component generating unit 4100 e , an adder 4300 , and a multiplier 4400 .

[0159] The crank input torque is input to an emphasized component generating section 4100e and a torque smoothing section 4200. The torque smoothing section 4200 performs a smoothing process on the crank input torque to generate a smoothed crank input torque.

[0160] This smoothed crank input torque is added to the emphasized component, which is the output of the emphasized component generating unit 4100e, in an adder 4300, and further multiplied by a predetermined assist ratio in a multiplier 4400 to generate the motor drive output, which is the output of the drive control unit.

[0161] The emphasized component generator 4100e in this embodiment is similar to the emphasized component generator 4100d shown in FIG. 15 , except that it employs a modulation function unit 4700 and an emphasis adjustment unit 4800. Specifically, the modulation function unit 4700 receives the crank rotation speed as an input and outputs a numerical value representing the level of the crank rotation speed. For example, the crank rotation speed [rpm] may be converted to vehicle speed units [km / h] using a gear ratio or the like to calculate the crank rotation-converted vehicle speed [km / h], and the rotation speed [rpm] of the motor 105 obtained from a Hall signal or the like may be converted to vehicle speed [km / h] to calculate the crank rotation-converted vehicle speed / vehicle speed. The crank rotation-converted vehicle speed / vehicle speed is an index value that can be considered the degree of tracking or agreement of the crank rotation with the vehicle speed. Alternatively, the crank rotation speed may simply be multiplied by a constant coefficient. If the crank rotation sensor 104 can detect the rotation direction of the crank, the crank rotation speed may be regarded as 0 when it detects that the crank rotation speed is negative (i.e., reverse rotation). However, even if the crank rotation speed is negative, the value may be used as is. In this case, if the crank is rotating in the reverse direction, a greater intention to decelerate is reflected.

[0162] The emphasis adjustment unit 4800 adjusts the output of the peak hold unit 3130 in accordance with the output from the modulation function unit 4700. As will be shown later as an example, when crank rotation converted vehicle speed / vehicle speed is 1, that is, when the crank rotation converted vehicle speed and the vehicle speed are the same, a relatively small gain is applied to the output of the peak hold unit 3130, and when crank rotation converted vehicle speed / vehicle speed is a value smaller than 1, a larger gain is applied to the output of the peak hold unit 3130. The emphasis component adjusted by the emphasis adjustment unit 4800 in this manner is output to the adder 4300 as the output of the emphasis component generation unit 4100e.

[0163] Fig. 21 is a timing chart showing an example of the operation of the drive control unit according to the fourth embodiment. Fig. 21 shows (a) the change over time of the crank input torque (solid line) and the smoothed crank input torque (dotted line), (b) the change over time of the crank input torque one crank rotation ago, (c) the change over time of the crank rotation converted vehicle speed (solid line) and the vehicle speed (dotted line), (d) the change over time of the modulation function output, (e) the change over time of the emphasis component, and (f) the change over time of the motor drive output.

[0164] As shown in Figures 21(a) to 21(c), the user increases crank rotation just before time t31, and from time t31, the crank torque sensor 103 detects the pedal force (i.e., increases the force). At time t32, the pedal force is barely detected by the crank torque sensor 103 (i.e., decreases the force). However, during this time, the freewheel is locked, and the crank rotation-equivalent vehicle speed matches the vehicle speed, with little change. Thereafter, at time t33, the pedal force is detected again (i.e., a second increase in the force), and at time t34, the pedal force is no longer detected again, resulting in a sudden decrease in crank rotation. However, even after time t33, the vehicle speed itself remains almost unchanged.

[0165] 21D, the output of modulation function unit 4700 is small before time t31 when the crank is not rotating much, and increases accordingly as the crank rotation speed increases just before time t31, until at time t31 the crank rotation converted vehicle speed matches the vehicle speed and becomes 1. In this example, the output of modulation function unit 4700 remains 1 from time t31 to time t34, and as the crank rotation speed suddenly decreases at time t34, the output of modulation function unit 4700 also becomes smaller. As described above, the smaller the output of modulation function unit 4700, the larger the gain applied by emphasis adjustment unit 4800, so a relatively small gain is applied from time t31 to t33, and the gain changes to decrease just before time t34 and then increases just after time t34.

[0166] 21( e), in the first power reduction at time t32, the gain applied by the emphasis adjustment unit 4800 is small, and the negative emphasis component in portion X is relatively small, while in the second power reduction at time t34, the gain applied by the emphasis adjustment unit 4800 is large, and the negative emphasis component in portion Y is larger than in the first power reduction. Note that, for the first and second power increases, the output of the modulation function unit 4700 is the same, and so the emphasis components for these increases are approximately the same.

[0167] The emphasized component shown in FIG. 21(e) is added to the smoothed crank input torque to produce the motor drive output shown in FIG. 21(f).

[0168] Generally, when the crank rotation converted vehicle speed and the vehicle speed are the same, the crank is rotating at a reasonable speed, and cruising or acceleration is desired depending on the situation. Even if the crank input torque decreases in such a state, a large negative emphasis component is often inappropriate. On the other hand, when the crank rotation converted vehicle speed and the vehicle speed deviate from each other, that is, when the crank rotation speed decreases, a large negative emphasis component is appropriate compared to the former case, since deceleration is desired.

[0169] In this way, it becomes possible to reflect not only the crank input torque but also the change in crank rotation speed, which reflects the user's intention, in the emphasis component.

[0170] The features of this embodiment are applicable not only to the third embodiment, but also to the second embodiment, its variants 1 and 2, and variant 1 of the third embodiment.

[0171] Furthermore, in the above example, the emphasis component is adjusted using the crank rotation speed, but the emphasis component may also be adjusted in accordance with the vehicle speed or the smoothed crank input torque.

[0172] [Fifth Embodiment] It is also possible to add the crank rotation speed to the emphasis component in a manner different from that of the fourth embodiment.

[0173] In this embodiment, an amount corresponding to the crank rotation speed is combined with the crank input torque, and the result is input to an emphasis component generating section 4100d to generate an emphasis component.

[0174] As shown in Fig. 22, the drive control unit according to this embodiment includes a torque smoothing unit 4200, an emphasis component generating unit 4100d, an adder 4300, a multiplier 4400, a modulation function unit 4700b, and an adder 4900. Components having the same functions as those described above are denoted by the same reference numerals. Also in this embodiment, a case will be described in which a 32-pulse shift clock is generated per half crank rotation.

[0175] The crank input torque is input to an adder 4900 and a torque smoothing unit 4200. The torque smoothing unit 4200 performs a smoothing process on the crank input torque to generate a smoothed crank input torque.

[0176] This smoothed crank input torque is added to the emphasized component, which is the output of the emphasized component generating unit 4100d, in an adder 4300, and then multiplied by a predetermined assist ratio in a multiplier 4400 to generate the motor drive output, which is the output of the drive control unit.

[0177] However, the input to emphasized component generator 4100d is not the crank input torque but the output of adder 4900. That is, adder 4900 adds the crank input torque and the output of modulation function section 4700b, and the addition result is input to one-rotation delay section 4113, adder 312, and adder 322 of emphasized component generator 4100d. However, instead of simple addition, synthesis such as weighted addition may also be used.

[0178] The modulation function unit 4700b has the same function as the modulation function unit 4700 of the fourth embodiment, and outputs a numerical value representing the degree of high or low of the crank rotation speed to the adder 4900. As described above, for example, crank rotation converted vehicle speed / vehicle speed is used as an index value such as the degree of tracking or agreement of the crank rotation with the vehicle speed.

[0179] In this way, when generating an emphasis component based on a composite value of the crank input torque and the output of the modulation function section 4700b, it is possible to understand information specific to electrically assisted bicycles, i.e., the user's intention as reflected not only in changes in pedal force but also in the crank rotation itself, thereby enabling more appropriate emphasis. For example, when re-accelerating from a stopped crank position, the crank rotation always increases before the crank input torque increases, allowing for earlier and stronger acceleration emphasis. Conversely, compared to when only the crank input torque is reduced to near zero from an accelerating or cruising state and the crank continues to rotate, by reducing the input torque and then reducing it to crank rotation, it is possible to more strongly emphasize the deceleration side, and it is also possible to achieve an effect similar to engine braking.

[0180] A timing chart illustrating an example of the operation of the drive control unit according to this embodiment is shown in Fig. 23. In Fig. 23, (a) represents the time changes in the crank input torque (solid line) and the smoothed crank input torque (dotted line), (b) represents the time changes in the crank rotation converted vehicle speed (solid line) and the vehicle speed (dotted line), (c) represents the time changes in the output of the modulation function unit 4700b, (d) represents the time changes in the composite value of the crank input torque and a numerical value representing the degree of high or low of the crank rotation speed, which is the input to the emphasis component generation unit 4100d, (e) represents the time changes in the composite value delayed by one crank rotation, (f) represents the time changes in the emphasis component, and (g) represents the time changes in the motor drive output.

[0181] Figure 23 shows a similar situation to Figure 21, where Figure 23(a) is the same as Figure 21(a), and Figure 23(b) is the same as Figure 21(c). Since modulation function section 4700b uses a similar function to modulation function section 4700, Figure 23(c) is also almost the same as Figure 21(d).

[0182] In this embodiment, the emphasized component is generated by a composite value of the crank input torque and a numerical value representing the degree of high or low in the crank rotation speed, so that the composite value, as shown in Figure 23(d), increases from just before time t31 and, from time t31 to time t34, forms a waveform in which the crank input torque is raised by an amount corresponding to the numerical value representing the degree of high or low in the crank rotation speed. After time t34, the composite value decreases to a constant value and is maintained at that value. A waveform delayed by one crank rotation also has a similar waveform.

[0183] Comparing the waveforms in Figure 23(d) and Figure 23(e), when the force is increased around time t31, the waveform is already lifted up by an amount representing the degree of crank rotation speed, and the waveform from one crank rotation prior, when neither the crank input torque nor the crank rotation has been detected, is compared, and the difference in the composite values ​​is evaluated to be large, resulting in a large positive emphasis component, as shown in portion AA1 of Figure 23(f). On the other hand, when the force is increased again at time t33 after being reduced once, both the waveforms in Figure 23(d) and (e) have been lifted up by an amount representing the degree of crank rotation speed, and the difference in the composite values ​​is evaluated to be smaller than that at the first increase, resulting in a relatively small positive emphasis component, as shown in portion AA2 of Figure 23(f).

[0184] Furthermore, when the force is reduced around time t32, both the waveforms in Figure 23(d) and (e) are raised by an amount representing the degree of the crank rotation speed, so the difference in the composite values ​​is evaluated to be small, and a relatively small negative emphasis component is obtained, as shown in portion AB1 of Figure 23(f). On the other hand, when the force is reduced again around time t34 after being increased again, the composite value shown in Figure 23(d) quickly decreases to a constant value and remains at that constant value, whereas the composite value from one crank rotation ago remains raised by an amount representing the degree of the crank rotation speed, so the difference in the composite values ​​is evaluated to be larger than that at the first force reduction, and a large negative emphasis component is obtained, as shown in portion AB2 of Figure 23(f).

[0185] Therefore, such an emphasis component is also reflected in the motor drive output shown in FIG.

[0186] In this embodiment, an emphasis effect according to the value representing the degree of crank rotation speed is produced not only when the crankshaft is reduced but also when the crankshaft is increased. When the crankshaft rotation speed transitions from a low state to a high state and the crankshaft input torque increases accordingly, it is preferable to increase the emphasis component to a positive value. On the other hand, even if the crankshaft input torque increases from zero in a situation where the freewheel is already locked and the crankshaft rotation converted vehicle speed matches the vehicle speed, this means that the vehicle is traveling at a certain vehicle speed, and the intention to increase the speed is not as great as when the crankshaft rotation speed transitions from a low state to a high state, so it is preferable to generate a relatively small positive emphasis component.

[0187] As described above, the emphasis component can be appropriately adjusted by using a value that indicates the degree of high or low of the crank rotation speed.

[0188] The features of this embodiment are applicable not only to the third embodiment, but also to the second embodiment, its variants 1 and 2, and variant 1 of the third embodiment.

[0189] Furthermore, although the example above shows the use of crank rotation speed as the input to modulation function section 4700b, a modulation function according to vehicle speed or smoothed crank input torque may also be used.

[0190] [First Modification of Fifth Embodiment] In the fifth embodiment, the crank input torque and the numerical value representing the degree of high or low of the crank rotation speed, which is the output of the modulation function unit 4700b, are combined, and an emphasis component is generated according to the increase or decrease thereof. However, similar results can be obtained by generating emphasis components according to the increase or decrease for each and then combining them.

[0191] For example, as shown in Fig. 24, the drive control unit according to this modification includes an emphasized component generating unit 4100d, a second emphasized component generating unit 6000, a torque smoothing unit 4200, a combining unit 7000, an adder 4300, and a multiplier 4400. Note that components having the same functions as those described above are given the same reference numerals. Also in this embodiment, a case will be described in which a shift clock of 32 pulses is generated per half crank rotation.

[0192] The crank input torque is input to a torque smoothing unit 4200 and an emphasized component generating unit 4100d. The torque smoothing unit 4200 performs a smoothing process on the crank input torque to generate a smoothed crank input torque.

[0193] This smoothed crank input torque is added by an adder 4300 to the combined result of the first emphasized component output by the emphasized component generating section 4100d and the second emphasized component output by the second emphasized component generating section 6000, and is further multiplied by a predetermined assist ratio by a multiplier 4400 to generate the motor drive output that becomes the output of the drive control section.

[0194] The synthesis unit 7000 synthesizes the first emphasized component output from the emphasized component generation unit 4100d and the second emphasized component output from the second emphasized component generation unit 6000, for example, by simple addition or weighted addition.

[0195] The emphasized component generator 4100d has a configuration similar to that shown in Fig. 15. The second emphasized component generator 6000 also has functions similar to those of the emphasized component generator 4100d, and includes a modulation function unit 4700c, a one-rotation delay unit 6100, a second increase detector 6200, a second peak hold unit 6300, and a second decrease detector 6400.

[0196] The modulation function unit 4700c has the same function as the modulation function units 4700 and 4700b described above, and outputs a numerical value that indicates the degree of high or low of the crank rotation speed. As described above, for example, crank rotation converted vehicle speed / vehicle speed is used as an index value such as the degree of tracking or agreement of the crank rotation with the vehicle speed.

[0197] The output of the modulation function unit 4700c is input to a one-rotation delay unit 6100, a second increase detection unit 6200, and a second decrease detection unit 6400. The one-rotation delay unit 6100 is, for example, a 64-stage shift register that delays the output of the modulation function unit 4700c by one crank rotation, and outputs the output delayed by one crank rotation to the second increase detection unit 6200 and the second decrease detection unit 6400.

[0198] The second increase detection unit 6200 includes an adder 621, a multiplier 622, and a second positive-side adjustment unit 623. The multiplier 622 generates a threshold value in the increase direction by multiplying the output of the one-rotation delay unit 6100, i.e., the output of the modulation function unit 4700c one crank rotation ago, by a third ratio Thpv (also referred to as a one-rotation increase ratio threshold of the crank rotation speed, which is greater than 1). The adder 621 also performs a calculation to subtract the threshold value in the increase direction from the current output of the modulation function unit 4700c. The result of this calculation is output to the second positive-side adjustment unit 623, which applies a predetermined gain to the output of the adder 621 and performs negative value clipping processing, outputting the output of the adder 621 as zero if the output is negative. Note that the predetermined gain may not be applied. The output of the second positive-side adjustment unit 623 is output to the second positive peak hold unit 631 of the second peak hold unit 6300. The second positive peak hold unit 631 is similar to the positive peak hold unit 3131 .

[0199] By employing such a second increase detection unit 6200, the current output of the modulation function unit 4700c is output to the second positive side adjustment unit 623 by an amount equal to or greater than Thpv times (>1) the output of the modulation function unit 4700c from one crank rotation ago, and if this output is a positive value, it is processed by the second positive peak hold unit 631. Here, for example, Thpv=1.4. It should be noted that, for example, Thp=1.15 in the emphasized component generation unit 4100d.

[0200] Similarly, the second decrease detection unit 6400 includes an adder 641, a multiplier 642, and a second negative-side adjuster 643. The multiplier 642 generates a threshold value in the decrease direction by multiplying the output of the modulation function unit 4700c one crank rotation ago by a fourth ratio Thnv (also referred to as a one-rotation decrease ratio threshold of the crank rotation speed, which is a value smaller than 1). The adder 641 also performs a calculation to subtract the threshold value in the decrease direction from the current output of the modulation function unit 4700c. The result of this calculation is output to the second negative-side adjuster 643, which applies a predetermined gain (which may be the same as or different from the gain of the second positive-side adjuster 623) to the output of the adder 641 and performs positive-value clipping processing to output the output of the adder 641 as zero if the output is positive. In some cases, the predetermined gain is not applied. The output of the second negative-side adjuster 643 is output to the second negative peak hold unit 632 of the second peak hold unit 6300. The second negative peak hold unit 632 is similar to the negative peak hold unit 3132.

[0201] By employing such a second decrease detection unit 6400, the current output of the modulation function unit 4700c is output to the second negative side adjustment unit 643 by the amount that is less than or equal to Thnv times (<1) the output of the modulation function unit 4700c from one crank rotation ago, and if this output is a negative value, it is processed by the second negative peak hold unit 632. Here, for example, Thnv=0.8. Note that, for example, Thp=0.6 in the emphasized component generation unit 4100d.

[0202] The second peak hold unit 6300 has a second positive peak hold unit 631, a second negative peak hold unit 632, and an adder 633, and adds the output of the second positive peak hold unit 631 and the output of the second negative peak hold unit 632, and outputs the result to the combining unit 7000. The adder 633 may perform other operations for combining, such as weighted addition, instead of simple addition.

[0203] In this way, it is possible to provide different nonlinear responses to the crank input torque and the output of the modulation function section 4700c. It is also possible to provide the output of the modulation function section 4700c with asymmetric nonlinear responses during acceleration and deceleration.

[0204] When the above-described numerical examples are adopted, it is possible to reduce the influence of changes in the crank rotation speed during acceleration and to increase the influence of changes in the crank rotation speed during deceleration, and it is also possible to emphasize the deceleration emphasis effect when the crank rotation speed decreases, as in the fourth embodiment.

[0205] The features of this embodiment are applicable not only to the third embodiment, but also to the second embodiment, its variants 1 and 2, and variant 1 of the third embodiment.

[0206] Furthermore, although the example above shows that the crank rotation speed is used as the input to the modulation function section 4700c, a modulation function according to the vehicle speed or smoothed crank input torque may also be used.

[0207] Furthermore, although one-rotation delay unit 6100 was used in the above, since the crank rotation speed does not vary periodically, a different delay amount may be used. For example, a delay equivalent to another arbitrary angle may be used, or a fixed time delay may be used instead of an angle synchronized with the crank rotation.

[0208] Although the embodiments of the present invention have been described above, the present invention is not limited to these. For example, depending on the purpose, any technical feature in each of the above-described embodiments or modifications may be deleted, or any technical feature described in another embodiment may be added. Furthermore, any technical feature in any of the embodiments may be combined.

[0209] Furthermore, the functional block diagram described above is an example, and one functional block may be divided into multiple functional blocks, or multiple functional blocks may be integrated into one functional block. Furthermore, the present embodiment is applicable not only to electrically assisted vehicles that implement both a self-propelled motorcycle mode and an assist mode, but also to electrically assisted vehicles that implement only one of the modes, and other electric vehicles.

[0210] The above-described embodiment can be summarized as follows.

[0211] The motor control device according to the present invention includes (A) a smoothing unit that smooths a drive operation amount related to an operation input for driving a motor, (B) a generating unit that generates a component for emphasizing an increase or decrease in the drive operation amount in accordance with the increase or decrease, and (C) a control unit that controls the drive of the motor based on the result of combining the smoothed drive operation amount and the above-mentioned component.

[0212] Since the drive of the motor is controlled using a component that emphasizes the increase or decrease in the operation drive amount as described above, the responsiveness of the motor drive in the electric vehicle is improved. Furthermore, since the component is combined with the smoothed drive operation amount, smoothness of the motor drive is also imparted. Furthermore, since not only an increase but also a decrease in the drive operation amount is handled, braking responsiveness is also improved.

[0213] Note that there may be nonlinearity between the increase / decrease in the drive operation amount and the above-mentioned component. A dead band, a progressive, a saturation, etc. may be defined for the relationship between the increase / decrease in the drive operation amount and the above-mentioned component. For example, as the nonlinearity described above, there may be a range for the increase / decrease in the drive operation amount within which the above-mentioned component becomes zero even if there is an increase / decrease in the drive operation amount.

[0214] Furthermore, the nonlinearity may be varied according to the drive operation amount, the smoothed drive operation amount, or the speed of the vehicle driven by the motor. For example, the dead band may be narrowed when the drive operation amount or the smoothed drive operation amount is small compared to when it is large, or when it is small compared to when the speed is high.

[0215] Furthermore, the nonlinearity described above may have asymmetry between the increase side of the drive operation amount and the decrease side of the drive operation amount, because different emphasis may be preferable during acceleration and deceleration.

[0216] The above-described generating unit may perform at least one of the following processes: when the first value representing the degree of increase in the drive operation amount increases and detects a maximum value of the first value, gradually decreasing the component from the maximum value toward zero; and when the second value representing the degree of decrease in the drive operation amount decreases and detects a minimum value of the second value, gradually increasing the component from the minimum value toward zero. In this way, the peak hold process may be performed on at least one of the increasing side and decreasing side of the drive operation amount. The peak hold process may also include a process of maintaining the peak.

[0217] Furthermore, the above-mentioned generating unit may determine an increase or decrease in the amount of drive operation by comparing the current amount of drive operation with a value obtained by multiplying the amount of drive operation at a predetermined time in the past (which may be a predetermined period of time or a predetermined number of shift clocks based on the crank rotation period (which may not be just half a rotation or one rotation)) by a predetermined coefficient. For example, in the case of an increase, an increase is determined when the amount of drive operation has increased by a factor greater than 1, and in the case of a decrease, a decrease is determined when the amount of drive operation has decreased by a factor less than 1. Note that the predetermined coefficient for an increase may be different from or the same as (1 - predetermined coefficient) and the predetermined coefficient for a decrease may be the same. Furthermore, the comparison result may be amplified by a predetermined gain.

[0218] Furthermore, the drive operation amount described above may fluctuate periodically. In this case, the generation unit described above may determine the increase or decrease in the drive operation amount by comparing the current drive operation amount with the drive operation amount an integer number of periods before the current drive operation amount. In the case of a drive operation amount such as the crank input torque of an electrically assisted bicycle, this makes it possible to determine the increase or decrease after excluding the periodic fluctuation factor. As described above, in the case of crank input torque, one period is half a crank rotation, and two periods is one crank rotation. By comparing with the drive operation amount one crank rotation before, the influence of the difference in left and right leg strength can be suppressed.

[0219] Furthermore, when the drive operation amount fluctuates periodically in synchronization with the crank rotation, the above-described generating unit may determine the increase or decrease in the drive operation amount by (a) comparing the current drive operation amount with a value obtained by multiplying the drive operation amount half a crank rotation or one crank rotation before the current drive operation amount by a predetermined coefficient, or (b) comparing a first value obtained by calculating a moving average of the drive operation amount for half a crank rotation or one crank rotation with the first value a predetermined sample period ago (typically one sample period ago). The case of (a) is similar to the case of comparing the current drive operation amount with a value obtained by multiplying the drive operation amount at a predetermined timing in the past by a predetermined coefficient. The case of (b) is similar to the case of comparing the increase or decrease in the drive operation amount with the drive operation amount an integer number of cycles before the current drive operation amount. Note that the comparison result may be amplified by a predetermined gain.

[0220] Furthermore, when the drive operation amount fluctuates periodically in synchronization with the crank rotation, the generating unit may generate the component by combining a first component based on a first comparison between the current drive operation amount and the drive operation amount half a crank rotation ago, and a second component based on a second comparison between the current drive operation amount and the drive operation amount one crank rotation ago. This corresponds to the case where the force is increased or decreased per half crank rotation while eliminating the influence of the difference in left and right leg strength.

[0221] Furthermore, a first range for an increase or decrease in the amount of drive operation, in which the first component is zero even if the amount of drive operation increases or decreases, and a second range for an increase or decrease in the amount of drive operation, in which the second component is zero even if the amount of drive operation increases or decreases, may be different.

[0222] The above-described generating unit may combine the first component and the second component by weighted addition, or may combine the first component and the second component by adopting the one with the larger absolute value. Other calculations may also be used.

[0223] Furthermore, the drive operation amount may be a crank input torque, in which case the above-mentioned generating unit may change the degree of emphasis according to an increase or decrease in the crank input torque in accordance with the crank rotation speed, because the crank rotation speed is also useful as a parameter representing the user's intention to accelerate or decelerate.

[0224] The generating unit may generate the component in accordance with a second drive operation amount related to an operation input for driving the motor. For example, a numerical value representing the degree of high or low of the crank rotation speed may be adopted as the second drive operation amount.

[0225] Furthermore, the above-described drive operation amount may be crank input torque, and the above-described second drive operation amount may be crank rotation speed. In this case, the above-described generation unit may generate the above component according to a composite value of the crank input torque and a value representing the level of the crank rotation speed. For example, even if the crank input torque increases when the crank rotation speed is already high, a smaller emphasized component may be generated compared to when the crank input torque increases as the crank rotation speed increases, or even if the crank rotation speed is high and the crank input torque decreases, a smaller emphasized component may be generated compared to when the crank input torque decreases as the crank rotation speed decreases.

[0226] Alternatively, the above-mentioned drive operation amount may be crank input torque, and the above-mentioned second drive operation amount may be crank rotation speed. In this case, the above-mentioned generating unit may generate the above-mentioned components by combining a first component for emphasizing an increase or decrease in the crank input torque in accordance with the increase or decrease, and a second component for emphasizing an increase or decrease in the crank rotation speed in accordance with the increase or decrease in a numerical value representing the degree of high or low.

Claims

1. A motor control device comprising: a smoothing unit that smooths a drive operation amount related to an operation input for driving a motor; a generation unit that generates a component for emphasizing an increase or decrease in the drive operation amount in accordance with the increase or decrease; and a control unit that controls the drive of the motor based on a synthesis result of the smoothed drive operation amount and the component.

2. The motor control device according to claim 1, wherein there is non-linearity between the increase or decrease in the drive operation amount and the component.

3. The motor control device according to claim 2, wherein as the non-linearity, a range is provided for the increase or decrease in the drive operation amount in which the component becomes zero even if there is an increase or decrease in the drive operation amount.

4. The motor control device according to claim 3, wherein the non-linearity changes in accordance with the drive operation amount.

5. The motor control device according to claim 4, wherein the non-linearity changes in accordance with the smoothed drive operation amount.

6. The motor control device according to claim 3, wherein the non-linearity changes in accordance with the speed of a vehicle moved by the motor.

7. The motor control device according to claim 3, wherein the non-linearity has asymmetry between the increasing side and the decreasing side of the drive operation amount.

8. The generation unit of the motor control device according to claim 1 executes at least one of: a process of gradually decreasing the component from the maximum value to zero when a first value representing the degree of increase in the drive operation amount increases and the maximum value of the first value is detected; and a process of gradually increasing the component from the minimum value to zero when a second value representing the degree of decrease in the drive operation amount decreases and the minimum value of the second value is detected.

9. The generation unit of the motor control device according to claim 1 specifies the increase or decrease in the drive operation amount by comparing a value obtained by multiplying the drive operation amount at a predetermined timing in the past by a predetermined coefficient with the current drive operation amount.

10. The drive operation amount varies periodically. The generation unit of the motor control device according to claim 1 specifies the increase or decrease in the drive operation amount by comparing the current drive operation amount with the drive operation amount one integer period before the current drive operation amount.

11. The drive operation amount varies periodically in synchronization with the crank rotation. The generation unit identifies an increase or decrease in the drive operation amount by comparing the current drive operation amount with a value obtained by multiplying the current drive operation amount by a predetermined coefficient and the drive operation amount half a crank rotation or one crank rotation before the current drive operation amount, or by comparing a first value obtained by moving-averaging the drive operation amount for half a crank rotation or one crank rotation with the first value before a predetermined sampling period. The motor control device according to claim 1.

12. The drive operation amount varies periodically in synchronization with the crank rotation. The generation unit generates the component by synthesizing a first component based on a first comparison between the current drive operation amount and the drive operation amount before half a crank rotation and a second component based on a second comparison between the current drive operation amount and the drive operation amount before one crank rotation. The motor control device according to claim 1.

13. A first range regarding an increase or decrease in the drive operation amount in which the first component becomes zero even if there is an increase or decrease in the drive operation amount is different from a second range regarding an increase or decrease in the drive operation amount in which the second component becomes zero even if there is an increase or decrease in the drive operation amount. The motor control device according to claim 12.

14. The generation unit synthesizes the first component and the second component by weighted addition. The motor control device according to claim 12.

15. The generation unit synthesizes by adopting the one with the larger absolute value among the first component and the second component. The motor control device according to claim 12.

16. The drive operation amount is the crank input torque. The generation unit changes the degree of emphasis according to an increase or decrease in the crank input torque according to the crank rotation speed. The motor control device according to claim 1.

17. The generation unit further generates the component according to a second drive operation amount regarding an operation input for driving the motor. The motor control device according to claim 1.

18. The drive operation amount is the crank input torque. The second drive operation amount is the crank rotation speed. The generation unit generates the component according to a composite value of the crank input torque and a value representing the level of high or low of the crank rotation speed. The motor control device according to claim 17.

19. The drive operation amount is the crank input torque, the second drive operation amount is the crank rotation speed, and the generation unit generates the component by synthesizing a first component for emphasizing the increase or decrease according to the increase or decrease of the crank input torque and a second component for emphasizing the increase or decrease according to the increase or decrease of a numerical value representing the degree of high or low of the crank rotation speed. The motor control device according to claim 17.

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