Patent Description:
Configurations of electric vehicles are known in which a power generator is actuated by an engine such as an internal combustion engine, and electric power generated by the power generator is supplied to a motor of a drive system. Such electric vehicles are referred to as series hybrid vehicles because the power generation system and the drive system are connected in series. In such series hybrid vehicles, various characteristic vibrations may occur; one example is torsional vibration or another type of natural vibration occurring in a shaft that transmits torque occurring in the engine to the power generator.

<CIT> discloses a feature of minimizing a natural vibration component generated in an electric vehicle. According to this feature, in a process of calculating a torque command value for a power generator, feedback (F/B) control is performed at the same time that feedforward (F/F) control is performed in order to control the vibration (damping).

Specifically, first, when the torque command value for the power generator is calculated, F/F filter processing is performed on a command value corresponding to a desired rotational speed to calculate an F/F torque command value. At the same time, F/B filtering is performed on a deviation between an estimated value and a measured value of rotational speed to calculate an F/B torque command value. The F/F torque command value and the F/B torque command value are added to derive a final torque command value for the power generator. By controlling the generator using such a final torque command value, it is possible to reduce the natural vibration component.

In a power generation system, an attenuator or another connecting part may be provided between the engine and the power generator as a countermeasure against noise and vibration. In such a power generation system, during an engine misfire or the like, a periodic disturbance other than the basic order (natural vibration component) of the engine may occur at the connecting part, resulting in system resonance. Because the periodic disturbance that causes such system resonance is different from the natural vibration component, problems have been presented in that the periodic disturbance cannot be reduced even if the feature disclosed in <CIT> is used.

Therefore, to resolve the problem described above, it is an object of the present invention to provide a method and device for controlling a hybrid vehicle in which system resonance caused by a periodic disturbance other than the natural vibration component is suppressed.

A hybrid vehicle control method according to the present invention is described in appended Claim <NUM>.

A hybrid vehicle control method and device is also disclosed in <CIT>.

Embodiments of the present invention are described below with reference to the drawings.

<FIG> is a schematic diagram of an electric vehicle according to a first embodiment.

An electric vehicle <NUM> comprises a drive system <NUM> serving as a drive source, a power generation system <NUM> that supplies electric power to the drive system <NUM>, and a control system <NUM> that controls the drive system <NUM> and the power generation system <NUM>. The vehicle is also provided with a sensor group <NUM> that acquires values to be inputted to the control system <NUM>. An electric vehicle having a configuration in which the power generation system <NUM> and the drive system <NUM> are connected in series in this manner is referred to as a series hybrid vehicle.

In the drive system <NUM>, a drive motor <NUM> is connected to drive wheels 14A, 14B via a speed reducer <NUM> and a shaft <NUM>. In addition, DC power supplied from a battery <NUM> is converted to AC power in a drive inverter <NUM>. The drive motor <NUM> rotates by being supplied with the AC power converted by the drive inverter <NUM>, whereby the drive wheels 14A, 14B are driven. When the electric vehicle <NUM> performs regenerative braking, the AC power generated in the drive motor <NUM> is converted to DC in the drive inverter <NUM> and is then charged to the battery <NUM>. Thus, the battery <NUM> is configured to be capable of charging and discharging.

In the power generation system <NUM>, an engine <NUM> is connected to a power generator <NUM> via an attenuator <NUM>, and the power generator <NUM> is rotated by the driving of the engine <NUM> to generate power. AC power generated by the power generator <NUM> is supplied to the drive system <NUM> after being converted to DC power by a power generator inverter <NUM>.

The attenuator <NUM> is intended to suppress any fluctuation in torque transmitted from the engine <NUM> to the power generator <NUM>, an example being a spring member provided between an inner hub connected to a shaft of the engine <NUM> and an outer hub connected to a shaft of the power generator <NUM>. Having such a configuration, the attenuator <NUM> can absorb torque vibration caused by torsion of the inner hub and the outer hub. The attenuator <NUM> is one example of a part via which the engine <NUM> and the power generator <NUM> are connected; for example, a low-rigidity shaft connecting the engine <NUM> and the power generator <NUM> may be a connecting part.

The control system <NUM> controls the drive system <NUM> and the power generation system <NUM> on the basis of the vehicle speed, the amount of acceleration pedal operation, the slope, etc., inputted from the sensor group <NUM>. The control system <NUM> includes a system controller <NUM> that unifies the system, a drive motor controller <NUM> and battery controller <NUM> that control the drive system <NUM>, and a power generator controller <NUM> and engine controller <NUM> that control the power generation system <NUM>.

The system controller <NUM> unifies all operations of the drive motor controller <NUM>, the battery controller <NUM>, the power generator controller <NUM>, and the engine controller <NUM>. A power generation control unit <NUM> provided inside the system controller <NUM> controls the battery controller <NUM>, the power generator controller <NUM>, and the engine controller <NUM>. Thus, the amount of power generated in the power generation system <NUM> is controlled by controlling the driving of the engine <NUM> and the power generator inverter <NUM>.

The system controller <NUM> generates command values for the drive system <NUM> and the power generation system <NUM> in accordance with the amount of acceleration pedal operation by the driver, the vehicle speed, the slope, and other parameters associated with the vehicle status inputted from the sensor group <NUM>, and also with a state of charge inputted from the battery controller <NUM> and electric power that can be inputted and outputted.

The power generation control unit <NUM> computes a torque command value T* for the engine controller <NUM> and a rotational speed command value ωG* for the power generator controller <NUM> in order for the desired electric power to be generated in the power generation system <NUM>. When the engine <NUM> is rotatably driven according to the torque command value T*, the power generator <NUM> co-rotates with the engine <NUM>. The power generation control unit <NUM> can obtain the desired electric power from the power generation system <NUM> by controlling the power generator inverter <NUM> at the same time.

The drive motor controller <NUM> receives input of the states of rotational speed, voltage, and the like from the drive motor <NUM>. On the basis of these inputs, the drive motor controller <NUM> controls switching of the drive inverter <NUM> in order to realize the torque command value T* generated by the system controller <NUM>, so that the desired AC power is applied to the drive motor <NUM> and the desired torque is obtained.

The battery controller <NUM> is configured to be capable of two-way communication with the battery <NUM>, and the battery controller measures the state of charge (SOC) on the basis of the current and voltage charged and discharged in the battery <NUM> and outputs the measurement result to the system controller <NUM>. At the same time, the battery controller <NUM> computes the electric power that can be inputted to and outputted from the battery <NUM> in accordance with the temperature, internal resistance, SOC, and other parameters associated with the battery <NUM>, and outputs the computation result to the system controller <NUM>.

The power generator controller <NUM> is configured to be capable of detecting a rotation state of the power generator <NUM>, and the power generator controller controls the switching of the power generator inverter <NUM> so that the power generator <NUM> rotates according to the rotational speed command value ωG* generated by the power generation control unit <NUM>. The desired DC power can thereby be supplied from the power generation system <NUM> to the drive system <NUM>.

The engine controller <NUM> controls a throttle, ignition timing, and fuel injection amount of the engine <NUM> so that the engine <NUM> is driven according to the torque command value T* instructed from the system controller <NUM>, in accordance with the rotational speed and temperature of the engine <NUM>.

The sensor group <NUM> includes a vehicle speed sensor <NUM>, an accelerator position sensor <NUM>, and a slope sensor <NUM>. The vehicle speed sensor <NUM> is provided in parallel with the drive wheels 14A, 14B, and the like, and the vehicle speed sensor acquires the vehicle speed of the electric vehicle <NUM> by measuring rotational speeds of the drive wheels 14A, 14B. The accelerator position sensor <NUM> acquires the operated amount of the acceleration pedal. The slope sensor <NUM> detects a slope of a road on which the electric vehicle <NUM> is traveling. The vehicle speed, acceleration pedal operation amount, and slope acquired by the vehicle speed sensor <NUM>, the accelerator position sensor <NUM>, and the slope sensor <NUM> are inputted to the system controller <NUM>. The sensors included in the sensor group <NUM> of the present embodiment are one example, and the control system <NUM> may perform control in accordance with inputs from other sensors.

<FIG> is a block diagram of the details of the configuration of the power generator controller <NUM>. The power generator <NUM> co-rotates with the engine <NUM> driven according to the torque command value T*. The power generator controller <NUM> then controls the power generator inverter <NUM> so that the power generator <NUM> rotates according to the rotational speed command value ωG*. Thus, the desired electric power is generated in the power generator <NUM>, and the generated electric power is supplied to the drive system <NUM>.

The power generator controller <NUM> includes a power generation control device <NUM>, a current command value computation device <NUM>, a current control device <NUM>, a three-phase to two-phase current converter <NUM>, dq-axis adders 345d, 345q, a decoupling control device <NUM>, and a two-phase to three-phase voltage converter <NUM>. Detailed operations of these components shall be described below.

The power generation control device <NUM> receives input of the rotational speed command value ωG* generated by the system controller <NUM> and an actual rotational speed ωG of the power generator <NUM> inputted from a resolver 23A attached to the power generator <NUM>. The power generation control device <NUM> generates a final torque command value Tfin* such that the rotational speed of the power generator <NUM> reaches the rotational speed command value ωG*.

The current command value computation device <NUM> receives input of the final torque command value Tfin* generated by the power generation control device <NUM>, a DC voltage value Vdc used to generate a PWM signal in the power generator inverter <NUM>, and the actual rotational speed ωG detected by the resolver 23A. On the basis of these inputs the current command value computation device <NUM> generates dq-axis current command values Id*, Iq* for the power generator <NUM>.

The current control device <NUM> receives input of the dq-axis current command values Id*, Iq* from the current command value computation device <NUM> and dq-axis current measurement values Id, Iq from the three-phase to two-phase current converter <NUM>. The current control device <NUM> generates dq-axis voltage command values Vd*, Vq* so that the dq-axis currents Id, Iq come to be equal to the dq-axis current command values Id*, Iq*.

The three-phase to two-phase current converter <NUM> generates the dq-axis current measurement values Id, Iq by performing UVW-phase to dq-axis conversions on UV-axis current measurement values iu, iv detected in UV-axis current sensors 23U, 23V provided between the power generator inverter <NUM> and the power generator <NUM>. The total sum of UVW-phase current vectors is zero, and it is therefore possible to know the currents of all phases by measuring the currents of two phases (UV phases) of the UVW phases.

The dq-axis adders 345d, 345q are provided in a stage following the current control device <NUM>. The dq-axis adders 345d, 345q, respectively, add dq-axis voltage command values Vd*, Vq* outputted from the current control device <NUM> and dq-axis decoupling control command values Vd_dcpl*, Vq_dcpl* outputted from the decoupling control device <NUM> to generate final dq-axis voltage command values Vd*, Vq*.

The decoupling control device <NUM> receives input of the dq-axis current measurement values Id, Iq from the three-phase to two-phase current converter <NUM>, and calculates the dq-axis decoupling control command values Vd_dcpl*, Vq_dcpl* needed to cancel out an interference component generated between the d-axis and the q-axis.

Upon receiving the final dq-axis voltage command values Vd*, Vq* outputted from the dq-axis adders 345d, 345q, the two-phase to three-phase voltage converter <NUM> calculates UVW-phase voltage command values Vu*, Vv*, Vw* by performing dq-axis to UVW-phase conversion on these inputs. The two-phase to three-phase voltage converter <NUM> then outputs the UVW-phase voltage command values Vu*, Vv*, Vw* to the power generator inverter <NUM>.

The power generator inverter <NUM> performs PWM control in accordance with the UVW-phase voltage command values Vu*, Vv*, Vw*. As a result, AC power generated in the power generator <NUM> is converted to DC power and supplied to the drive system <NUM>.

If the final torque command value Tfin* generated in the power generation control device <NUM> is used as a command value, the components including the current command value computation device <NUM> through to the two-phase to three-phase voltage converter <NUM>, the power generator inverter <NUM>, and the power generator <NUM> constitute a plant <NUM>, which is a system to be controlled. Specifically, the plant <NUM> outputs generated power to the drive system <NUM> in response to the input of the final torque command value Tfin*, and causes the actual rotational speed ωG of the power generator <NUM> to be inputted as feedback to the power generation control device <NUM>.

<FIG> is a block diagram of control performed by the power generation control device <NUM>. This diagram shows the power generation control device <NUM> in a single-dot dashed line, and also shows the plant <NUM> to be controlled.

The power generation control device <NUM> outputs the final torque command value Tfin*, which is a command value for the plant <NUM>, in accordance with the input of the rotational speed command value ωG* from the system controller <NUM>, the feedback input of the actual rotational speed ωG from the power generator <NUM> constituting the plant <NUM>, and input of a misfire determination flag FLG for the engine <NUM>. The misfire determination flag FLG is detected due to, e.g., an abnormality in the rotational speed of the engine <NUM> being detected in the system controller <NUM>. The detailed configuration of the power generation control device <NUM> shall be described below.

The power generation control device <NUM> includes a rotational speed control unit <NUM>, a damping control unit <NUM>, and a damping control switching determination unit <NUM>.

The rotational speed control unit <NUM> receives the rotational speed command value ωG* generated by the system controller <NUM> (not shown in <FIG>) and the actual rotational speed ωG of the power generator <NUM>, which is part of the plant <NUM>. The rotational speed control unit <NUM>, for example, performs PI control so that the actual rotational speed ωG reaches the rotational speed command value ωG*, and generates a torque command value T* for performing rotational speed control. The torque command value T* is outputted to the damping control unit <NUM>.

Feedforward (F/F) control and feedback (F/B) control are performed in the damping control unit <NUM>. Specifically, the damping control unit <NUM> has a model matching unit <NUM> and an F/F switch <NUM> associated with F/F control, and a disturbance observer <NUM> and an F/B switch <NUM> associated with F/B control.

The model matching unit <NUM> is configured from a Gm(s)/Gp(s) filter, and the model matching unit performs F/F control to suppress vibration in a transmission system. Specifically, due to a Gm(s)/Gp(s) filter process being performed on the torque command value T*, F/F control having a high damping effect is performed and a model matching torque Tmm is generated. Gp(s) is a model indicating a transmission characteristic whereby torque T is inputted and a rotational speed ωG is outputted in the plant <NUM> (power generator <NUM>). Gm(s) is a model (ideal model) indicating a transmission characteristic whereby torque T is inputted and a rotational speed ωG is outputted in an ideal plant <NUM>.

The F/F switch <NUM>, in accordance with the input from the damping control switching determination unit <NUM>, switches between whether or not the filter process is being performed by the model matching unit <NUM> on the torque command value T* outputted from the rotational speed control unit <NUM>. When the F/F switch <NUM> is on, the model matching torque Tmm passed through the model matching unit <NUM> is outputted as F/F torque Tff. When the F/F switch <NUM> is off, the torque command value T* is outputted as F/F torque Tff without passing through the model matching unit <NUM>. The F/F torque Tff is one example of a first command value.

The disturbance observer <NUM> includes a disturbance estimation block <NUM>, a subtractor <NUM>, and an F/B filter <NUM>. The disturbance observer <NUM> calculates a disturbance estimation torque Tdist_est on the basis of the final torque command value Tfin* from the F/F switch <NUM> and the input of the actual rotational speed ωG from the plant <NUM>. The detailed configuration is as follows.

The disturbance estimation block <NUM> calculates an estimated rotational speed value ωGest by performing a process using the transmission characteristic Gp(s) of the plant <NUM> on the final torque command value Tfin* outputted from the F/F switch <NUM>.

The subtractor <NUM> calculates a deviation ΔωG by subtracting the actual rotational speed ωG outputted from the plant <NUM> from the estimated rotational speed value ωGest calculated by the disturbance estimation block <NUM>. The estimated rotational speed value ωGest is a value corresponding to a command value and the actual rotational speed ωG is a measurement value, and F/B control can therefore be performed on the basis of the deviation ΔωG therebetween.

The F/B filter <NUM> calculates the disturbance estimation torque Tdist_est by performing a filter process on the deviation ΔωG calculated by the subtractor <NUM>. The F/B filter <NUM> is an H(s)/Gp(s), and is configured from a <NUM>/Gp(s), which is an inverse of the transmission characteristic Gp(s) of the plant <NUM>, and a bandpass filter H(s) of which a central frequency matches a resonance frequency of the plant <NUM>. The resonance frequency of the plant <NUM> is a resonance frequency resulting from torsional vibration occurring in the attenuator <NUM>.

The F/B switch <NUM> switches between whether or not the disturbance estimation torque Tdist_est calculated by the disturbance observer <NUM> is being applied, in accordance with the input from the damping control switching determination unit <NUM>. When the F/B switch <NUM> is on, the disturbance estimation torque Tdist_est is outputted as F/B torque Tfb. When the F/B switch <NUM> is off, zero torque T<NUM> is outputted as the F/B torque Tfb. The F/B torque Tfb is an example of a second command value.

An adder <NUM> adds the F/F torque Tff outputted from the F/F switch <NUM> and the F/B torque Tfb outputted from the F/B switch <NUM>, and outputs the final torque command value Tfin*. The final torque command value Tfin* outputted from the adder <NUM> is inputted to the plant <NUM> after being affected by disturbance d. In this diagram, the disturbance d is shown in modeled form so as to have an effect via an adder 200a.

The damping control switching determination unit <NUM> switches the F/F switch <NUM> and the F/B switch <NUM> in the damping control unit <NUM>. The details of this switching control are shown in <FIG>.

<FIG> is a flowchart of damping control switching control performed by the damping control switching determination unit <NUM>. The damping control switching control is stored as a program in the controller constituting the control system <NUM>.

In step S1, the damping control switching determination unit <NUM> determines whether or not the misfire determination flag FLG indicating a misfire of the engine <NUM> has been received from the system controller <NUM>. When the misfire determination flag FLG is received (S1: Yes), the damping control switching determination unit <NUM> next performs the process of step S2. When the misfire determination flag FLG is not received (S1: No), the damping control switching determination unit <NUM> next performs the process of step S3.

In step S2, the damping control switching determination unit <NUM> turns both the F/F switch <NUM> and the F/B switch <NUM> off and stops both F/F and F/B damping control.

In step S3, the damping control switching determination unit <NUM> turns both the F/F switch <NUM> and the F/B switch <NUM> on and starts both F/F and F/B damping control.

Thus, during normal operation in which the misfire determination flag FLG has not been received, the damping control switching determination unit <NUM> operates with both the F/F switch <NUM> and the F/B switch <NUM> on. Specifically, F/F control and F/B control are performed, the model matching torque Tmm is outputted as F/F torque Tff, and the disturbance estimation torque Tdist_est is outputted as F/B torque Tfb. It is thereby possible to simultaneously suppress the torsional natural vibration component in the attenuator <NUM> and periodic disturbance (torque pulsation and the like) from the engine <NUM>.

When the misfire determination flag FLG has been received, the damping control switching determination unit <NUM> operates with both the F/F switch <NUM> and the F/B switch <NUM> off. Specifically, F/F control and F/B control are not performed, the torque command value T* used in rotational speed control is outputted as F/F torque Tff, and zero torque T<NUM> is outputted as F/B torque Tfb.

When the engine <NUM> misfires, a periodic disturbance other than the natural vibration component of the plant <NUM> occurs. Therefore, there is a risk that damping will not be possible even with the use of F/F control using the transmission characteristic Gp(s) of the plant <NUM> and F/B control using the output from the plant <NUM>. As a result, periodic disturbance other than the natural vibration component occurs in a state in which a torsion angle in the attenuator <NUM> exceeds an allowable range, and when damping control is performed, system resonance occurs as a result of the periodic disturbance. Such a phenomenon in the attenuator <NUM> is referred to as "bottoming out.

Thus, system resonance is avoided due to the damping control switching determination unit <NUM> turning both the F/F switch <NUM> and the F/B switch <NUM> off, and as a result, inputting of the torsion angle in the attenuator <NUM> does not exceed the allowable range, and the occurrence of bottoming out can be suppressed. Therefore, the occurrence of system resonance can be prevented.

The following is a description, given using <FIG> and <FIG>, of the effect obtained by performing a damping control switching determination such as is shown in the present embodiment.

<FIG> is a timing chart of drive states of a power generation system <NUM> of a comparative example. In the example in this chart, a damping control switching determination unit <NUM> such as that of the present embodiment is not provided, and damping control using F/F control and F/B control is performed in all time slots.

<FIG> is a chart of drive states of the power generation system <NUM> of the present embodiment. Therefore, the damping control switching determination unit <NUM> is provided and damping control is stopped when the engine <NUM> misfires.

<FIG> and <FIG> both show changes in three parameters: from the top down, the rotational speed of the engine <NUM>, the drive torque of the power generator <NUM>, and the torsional torque of the attenuator <NUM>. Specifically, these charts show the torque generated in the power generator <NUM> and the torsional torque in the attenuator <NUM> when the rotational speed of the engine <NUM> is swept so as to increase over time.

Comparing the two, the amplitude generated in the torque in the example of <FIG> is smaller than that of the example of <FIG>, particularly in the time slot near the center of the charts. Therefore, because the torque in the attenuator <NUM> does not exceed the allowable range (there is no bottoming out), any increase in the torsion angle of the shaft between the engine <NUM> and the power generator <NUM> is minimized, and it is possible to minimize the occurrence of system resonance caused by components other than the characteristic frequency.

In the present embodiment, an example was described in which the rotational speed of the power generator <NUM> is the object of control in the control of the actual rotational speed ωG of the power generator controller <NUM>, but this examples is not provided by way of limitation. The power generator controller <NUM> may control the rotational speed of the engine <NUM>.

According to the first embodiment, the following effects are obtained.

The electric vehicle <NUM> in which the control method of the first embodiment is used is a series hybrid vehicle in which the drive system <NUM> and the power generation system <NUM> are connected in series, and control of the rotational speed of the power generator <NUM> of the power generation system <NUM> is performed using the final torque command value Tfm*.

The power generation control unit <NUM> of the system controller <NUM> derives the rotational speed command value ωG* derived in accordance with the state of the drive system <NUM>. In the power generation control device <NUM>, the rotational speed control unit <NUM> derives the torque command value T* so that the actual rotational speed ωG of the power generator <NUM> reaches the rotational speed command value ωG*, and the damping control unit <NUM> performs damping control on the torque command value T*, whereby the final torque command value Tfin* is calculated.

For example, when the engine <NUM> misfires and system resonance occurs in the plant <NUM> as a result of a component other than the characteristic frequency, there is a risk that the torsion angle in the attenuator <NUM> will exceed the allowable range and vibration (periodic disturbance) other than the natural vibration component will occur. When this vibration occurs, system resonance will occur when damping control removing the natural vibration component is performed. Therefore, in cases such as when there could be vibration (periodic disturbance) that could cause system resonance, i.e., misfiring of the engine <NUM> is detected, the system resonance can be suppressed by switching the damping control switching determination unit <NUM> so as to not perform damping control.

In particular, when system resonance occurs, the torsion angle in the attenuator <NUM> connecting the engine <NUM> and the power generator <NUM> exceeds the allowable range, and there is a risk that the torque of the engine <NUM> will not be properly transmitted to the power generator <NUM> and there will be pronounced vibration and noise. However, due to the damping control switching determination unit <NUM> turning damping control off, system resonance is suppressed and abnormality in the torque transmission in the attenuator <NUM> can therefore be suppressed.

Conversely, when misfiring of the engine <NUM> is not confirmed and the damping control switching determination unit <NUM> is not receiving a misfire flag, the switches <NUM>, <NUM> are turned on and damping control is performed. As a result, damping control can be performed on the torsional natural vibration component of the attenuator <NUM> and on periodic disturbance (torque pulsation and the like) from the engine <NUM>.

According to the method for controlling the electric vehicle <NUM> of the first embodiment, in the damping control unit <NUM>, the model matching unit <NUM> calculates the model matching torque Tmm, which is the first command value, by performing feedforward control to reduce the torsional vibration component, the deviation ΔωG between the actual rotational speed ωG and the estimated rotational speed value ωGest derived on the basis of the final torque command value Tfin* is estimated as disturbance, and the disturbance estimation torque Tdist_est, which is the second command value, is derived by performing feedback control so that the disturbance is suppressed. The adder <NUM> then calculates the final torque command value Tfin* by adding the model matching torque Tmm and the disturbance estimation torque Tdist_est. Thus, more effective damping control can be performed by combining F/F control and F/B control.

By performing such damping control, the torsional natural vibration component of the attenuator <NUM> and periodic disturbance (torque pulsation and the like) from the engine <NUM> can be suppressed when system resonance does not occur; therefore, the natural vibration component of the plant <NUM> is suppressed and the power generation system <NUM> can be stably driven.

In the first embodiment, an example was described in which damping control is suppressed when the engine <NUM> misfires, but this example is not provided by way of limitation. In the second embodiment, an example is described of a case in which a condition of suppressing damping control is that rotational speed be comparatively high.

<FIG> is a block diagram of control performed by the power generation control device <NUM> of the second embodiment. Comparing this block diagram with the block diagram relating to the power generation control device <NUM> of the first embodiment shown in <FIG>, the input to the damping control switching determination unit <NUM> is changed to the rotational speed ωG outputted from the plant <NUM>.

<FIG> is a flowchart of damping control switching control performed by the damping control switching determination unit <NUM>.

In step S1, the damping control switching determination unit <NUM> determines whether or not the rotational speed ωG outputted from the plant <NUM> is greater than a predetermined threshold value ωGth. The threshold value ωGth in this embodiment is a rotational speed of the power generator <NUM> at which there is a high possibility of misfiring of the engine <NUM> and the like. Therefore, when the rotational speed ωG of the engine <NUM> is greater than the predetermined threshold value ωGth, there is a high possibility of system resonance occurring.

When the rotational speed ωG is greater than the predetermined threshold value ωGth (S1: Yes), the damping control switching determination unit <NUM> next performs the process of step S2 and suppresses damping control. When the rotational speed ωG is not greater than the predetermined threshold value ωGth (S1: No), the damping control switching determination unit <NUM> next performs the process of step S3 and performs damping control.

Thus, when the rotational speed ωG is comparatively low, the damping control switching determination unit <NUM> operates with both the F/F switch <NUM> and the F/B switch <NUM> on. When the rotational speed ωG is comparatively high, the damping control switching determination unit <NUM> operates with both the F/F switch <NUM> and the F/B switch <NUM> off.

The engine <NUM>, unlike a comparatively large engine connected to drive wheels, is used only for power generation and therefore has a high possibility of misfiring. When the engine <NUM> misfires, there is a risk that vibration (periodic disturbance) other than the natural vibration component will occur and system resonance will occur. Therefore, the system resonance can be reduced by suppressing damping control in cases in which the rotational speed ωG of the power generator <NUM> is comparatively high, such as when combustion is occurring in the engine <NUM>. As a result, occurrences of pronounced vibration (bottoming out) can be suppressed as a result of avoiding inputting of a torsion angle in the allowable range in the attenuator <NUM>. When the rotational speed ωG of the power generator <NUM> is comparatively low, a motoring stage is entered, during which combustion in the engine <NUM> has not been started, vibration (periodic disturbance) does not readily occur, and system resonance does not readily occur. Therefore, vibration of the natural vibration component can be suppressed by performing damping control, and vibration of the entire system can be reduced.

To compare the rotational speed ωG and the combustion state during startup of the engine <NUM>, first the power generator <NUM> is driven as a starter and rotation is started (motoring). Then, the rotational speed ωG increases, ignition occurs in the engine <NUM>, and when the rotational speed ωG further increases, combustion (firing) stably occurs in the engine <NUM>. After ignition has occurred in the engine <NUM>, there is a high possibility that the engine <NUM> will misfire and system resonance will occur. Therefore, the threshold value ωGth is set as the rotational speed at which combustion after motoring will be started and damping control is turned off when the rotational speed ωG is greater than the threshold value ωGth, whereby system resonance resulting from misfiring can be suppressed, and as a result, bottoming out of the attenuator <NUM> can be prevented.

According to the second embodiment, the following effects can be obtained.

According to the method for controlling the electric vehicle <NUM> of the second embodiment, when the rotational speed ωG after the engine <NUM> starts up is comparatively high, damping control is suppressed because there is a high risk that system resonance resulting from vibration (periodic disturbance) other than the natural vibration component will occur due to misfiring of the engine <NUM> or the like. Occurrences of system resonance are thereby suppressed, and as a result, inputting of a torsion angle in the allowable range in the attenuator <NUM> is avoided, and occurrences of pronounced vibration resulting from bottoming out can be suppressed.

When the rotational speed ωG is comparatively low, it can be assumed that the engine <NUM> is in a motoring state. Therefore, vibration other than the natural vibration component does not readily occur, system resonance does not readily occur, and vibration can be reduced by performing damping control. As a result, a command value that has undergone damping control is inputted to the plant <NUM>, and it is therefore possible to achieve a damping effect for the torsional natural vibration component of the attenuator <NUM> and for periodic disturbance from the engine <NUM> (engine torque pulsation or the like).

In addition, the time needed to determine switching in damping control is reduced by using the rotational speed ωG, in contrast to when a misfire determination is performed. As a result, when periodic disturbance occurs, damping control can be turned off sooner, and occurrences of system resonance can therefore be suppressed.

According to the method for controlling the electric vehicle <NUM> of the second embodiment, the threshold value ωGth used to determine switching in damping control using the rotational speed ωG can be set at the boundary between the rotational speed at which motoring is performed and the rotational speed at which combustion (firing) starts after motoring. When the rotational speed ωG is greater than the threshold value ωGth, a stage is entered at which firing of the engine <NUM> is started, and the possibility of system resonance occurring as a result of misfiring is therefore higher than in the motoring state. Therefore, occurrences of system resonance resulting from misfiring can be suppressed by turning damping control off. Conversely, when the rotational speed ωG is lower than the threshold value ωGth, motoring is performed; therefore, the possibility of misfiring of the engine <NUM> is low and the possibility of system resonance occurring is low. Therefore, the natural vibration component can be suppressed by turning damping control on.

In the second embodiment, an example was described of a case in which a condition of suppressing damping control is that rotational speed be comparatively high, but this example is not provided by way of limitation. In a third embodiment, an example is described in which a condition of suppressing damping control is that the output of the plant <NUM> (engine <NUM>/power generator <NUM>) be used.

<FIG> is a block diagram of control performed by the power generation control device <NUM> of the third embodiment. Comparing this block diagram with the block diagram relating to the power generation control device <NUM> of the second embodiment shown in <FIG>, the output of the plant <NUM> is inputted to the damping control switching determination unit <NUM> from the integrator <NUM>.

Specifically, the integrator <NUM>, upon receiving inputs of the rotational speed ωG from the plant <NUM> and the final torque command value Tfin* from the adder <NUM>, integrates the two inputs and outputs an output P to the damping control switching determination unit <NUM>.

In step S1, the damping control switching determination unit <NUM> determines whether or not the output P of the plant <NUM> is positive. When the output P is positive (S1: Yes), the damping control switching determination unit <NUM> next performs the process of step S2 and suppresses damping control. Conversely, when the output P is negative (S1: No), the damping control switching determination unit <NUM> next performs the process of step S3 and performs damping control.

Thus, when the output P is positive, the damping control switching determination unit <NUM> operates with both the F/F switch <NUM> and the F/B switch <NUM> on, Conversely, when the output P is negative, the damping control switching determination unit <NUM> operates with both the F/F switch <NUM> and the F/B switch <NUM> off.

In this embodiment, when the output P is positive, the power generator <NUM> is in a generating state and the engine <NUM> is motoring. Therefore, the risk of system resonance resulting from misfiring is low, and the vibration of the plant <NUM> can therefore be suppressed by turning damping control on. When the output P is negative, the power generator <NUM> generates power and combustion in the engine <NUM> proceeds. Therefore, the risk of system resonance resulting from misfiring is higher than in the motoring state, and damping control is therefore turned off. As a result, inputting of a torsion angle in the allowable range in the attenuator <NUM> is avoided, occurrences of pronounced vibration are suppressed, and as a result, it is possible to minimize occurrences of system resonance resulting from vibration (periodic disturbance) other than the natural vibration component.

In the third embodiment, the product of the rotational speed ωG and the final torque command value Tfin* is the output P, but this example is not provided by way of limitation. For example, the products of the dq-axis currents Id, Iq outputted from the three-phase to two-phase current converter <NUM> of <FIG> and the dq-axis voltage command values Vd*, Vq* outputted from the dq-axis adders 345d, 345q (Id×Vd*+Iq×Vq*) may be the output P.

According to the third embodiment, the following effects can be obtained.

According to the method for controlling the electric vehicle <NUM> of the third embodiment, when the output P of the power generator <NUM> is low, the power generator <NUM> generates power, and therefore the engine <NUM> fires. Damping control is suppressed because there is a high risk that system resonance will occur as a result of vibration (periodic disturbance) other than the natural vibration component due to misfiring or the like. Occurrences of system resonance are thereby minimized, and as a result, inputting of a torsion angle in the allowable range in the attenuator <NUM> is avoided, and occurrences of pronounced vibration are minimized. As a result, it is possible to minimize occurrences of system resonance resulting from vibration other than the natural vibration component. Conversely, when the output P of the power generator <NUM> is comparatively high, the engine <NUM> is motoring, vibration other than the natural vibration component does not readily occur, and system resonance does not readily occur; therefore, vibration can be reduced by performing damping control.

According to the method for controlling the electric vehicle <NUM> of the third embodiment, a threshold value Pth used to determine switching in damping control using the output P of the power generator <NUM> is set to zero. The firing/motoring state of the engine <NUM> and the power generation/regeneration state of the power generator <NUM> are thereby caused to correspond. As a result, when the output of the power generator <NUM> is positive and power is being generated, combustion is beginning in the engine <NUM>, the probability of misfiring is therefore higher, and it is therefore possible to minimize occurrences of system resonance by turning damping control off.

A switch is made between whether to perform or not perform damping control using the misfire determination flag FLG in the first embodiment, the rotational speed ωG in the second embodiment, and the output P of the plant <NUM> in the third embodiment, but these examples are not provided by way of limitation. When there is a risk of system resonance occurring as a result of vibration (periodic disturbance) other than the natural vibration component of the plant <NUM>, the system resonance can be minimized by omitting damping control.

Claim 1:
A hybrid vehicle control method for controlling a hybrid vehicle having a power generation system (<NUM>) in which an engine (<NUM>) and a drive shaft are connected and which includes a power generator (<NUM>) configured to rotate together with the engine (<NUM>), and a drive system (<NUM>) that is connected to the power generation system (<NUM>) and driven by receiving electric power supplied from a chargeable battery, comprising:
determining a rotational speed command value (ωG*) for the power generation system (<NUM>) in accordance with a state of the drive system (<NUM>);
determining a torque command value (T*) for the power generation system (<NUM>) such that a rotational speed of the power generation system (<NUM>) reaches the rotational speed command value (ωG*);
performing a damping control on the torque command value (T*) to suppress a natural vibration component generated in a connection between the engine (<NUM>) and the power generator (<NUM>) to calculate a final torque command value (Tfin*) for the power generation system (<NUM>);
setting the torque command value (T*) as the final torque command value (Tfin*) without performing the damping control upon determining a system resonance can occur that is caused by a vibration component different from the natural vibration component;
wherein the hybrid vehicle control method is characterized by
in the performing of the damping control,
calculating a first command value by subjecting the torque command value (T*) to feedforward control to reduce the natural vibration component,
determining a disturbance from a difference between a rotational speed measurement value and an estimated rotational speed value estimated based on the final torque command value,
calculating a second command value by performing feedback control so that the disturbance is suppressed, and
calculating the final torque command value (Tfin*) by adding the first command value and the second command value.