Control system for electric vehicles

Abstract

This invention provides a control system for electric vehicles that can reduce the discomfort caused to occupants by vibrations during power generation. [Solution] The hybrid vehicle (10) includes an engine (101), a power transmission path (G) that transmits power from the engine, a generator (103) that receives power from the engine and generates electricity, a vibration detector (107) that detects vibrations of the vehicle, and a control unit (100) that controls the engine by setting a target rotational speed of the engine according to the target amount of power generated during power generation. If the vibration of the vehicle exceeds a predetermined reference frequency during power generation, the control unit changes the target rotational speed so that the vibration detected by the vibration detector becomes smaller than the reference frequency.

Description

[Technical Field]

[0001] This disclosure relates to an electric vehicle in which a generator is driven by an engine (internal combustion engine) to generate electricity, and more particularly to a power generation control technology for such a vehicle. [Background technology]

[0002] In electric vehicles equipped with an engine and a generator, the engine initiates emergency power generation from the generator when the battery level falls below a certain value. Such emergency power generation can occur even in situations where the battery output is low, such as during traffic congestion, due to power consumption by auxiliary equipment, etc. It is known that when the engine starts driving the generator to generate power, a large vibration (rattling noise) occurs when the engine speed passes the vehicle's inherent resonant speed. An example of a technology to suppress such vibrations is disclosed in Patent Document 1.

[0003] According to Patent Document 1, the rotational speeds of the engine and generator are synchronized at a rotational speed higher than the vehicle's inherent resonant frequency, and then the clutch is controlled to connect the engine and generator, maintaining the engine's rotational speed at a higher speed than the synchronization speed. In other words, Patent Document 1 discloses a technique for suppressing rattling noise by controlling the rotational speeds of the engine and generator so that they do not reach the resonant frequency. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2016-030547 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, generally speaking, the vibrations during power generation that cause discomfort to vehicle occupants are not limited to just the so-called rattling noise. For example, noise and vibration when the engine speed increases can also cause discomfort to vehicle occupants.

[0006] This disclosure was devised in view of the aforementioned circumstances, and its purpose is to reduce the discomfort caused to occupants by vibrations during power generation in electric vehicles. [Means for solving the problem]

[0007] To achieve the above objective, according to one embodiment of the present disclosure, there is a control system for an electric vehicle including an engine, a power transmission path for transmitting power from the engine, and a generator that receives power from the engine via the power transmission path and generates electricity, the system comprising a vibration detector for detecting vibrations of the vehicle, and a control unit for controlling the engine by setting a target rotational speed of the engine according to a target amount of power generated during power generation, wherein the control unit changes the target rotational speed so that the vibration detected by the vibration detector becomes smaller than the reference frequency if the vibration of the vehicle exceeds a predetermined reference frequency during power generation. According to one embodiment of the present disclosure, the power transmission path may always transmit power from the engine to the generator.

[0008] According to one embodiment of the present disclosure, the control unit can change the target rotational speed when the speed of the vehicle is lower than a predetermined reference speed.

[0009] According to one embodiment of the present disclosure, the control unit can change the target rotational speed to a rotational speed higher than the engine rotational speed corresponding to the resonant vibration frequency of the vehicle.

[0010] According to one embodiment of the present disclosure, the system further includes a microphone for detecting the noise level inside the vehicle associated with the rotation of the engine, and the control unit can change the target rotation speed so that the noise level caused by the rotation of the engine falls below a predetermined standard.

[0011] According to an embodiment of the present disclosure, the control unit can change the target rotational speed so that the vibration detected by the vibration detector is minimized.

[0012] According to an embodiment of the present disclosure, there is a storage unit that stores a past changed target rotational speed that is less than the reference vibration value in association with the target rotational speed, and the control unit can change the target rotational speed to the changed target rotational speed stored in the storage unit during power generation.

[0013] According to an embodiment of the present disclosure, the storage unit further stores the changed target rotational speed in association with the vehicle speed when the changed target rotational speed is reached, and the control unit can change the target rotational speed to the changed target rotational speed corresponding to the vehicle speed during power generation.

[0014] According to an embodiment of the present disclosure, when the control unit changes the target rotational speed so that the vibration detected by the vibration detector is minimized, the changed target rotational speed is learned as the changed target rotational speed, and the target rotational speed can be changed to the learned changed target rotational speed during power generation.

[0015] According to an embodiment of the present disclosure, a vibration frequency setting unit that can be set by an operator for the reference vibration frequency may be further provided.

Advantages of the Invention

[0016] According to an embodiment of the present disclosure, since the rotational speed of the engine during power generation is changed to a value such that the vibration is below the standard, the discomfort caused by the vibration during power generation to the passengers can be reduced.

[0017] According to an embodiment of the present disclosure, in the case of a method of always transmitting the power of the engine to the generator, by changing the rotational speed of the engine, the discomfort caused by vibration can be more effectively reduced.

[0018] According to one embodiment of this disclosure, since vibrations during power generation are easily felt at low speeds, changing the target rotational speed can more effectively reduce discomfort caused by vibrations.

[0019] According to one embodiment of the present disclosure, unpleasant vibrations caused by resonance can be avoided by changing the target rotational speed to a rotational speed higher than the resonant rotational speed.

[0020] According to one embodiment of the present disclosure, by changing the target rotational speed so that the noise level is lower than the standard, the discomfort of the occupants due to noise can be reduced.

[0021] According to one embodiment of the present disclosure, by changing the target rotational speed to minimize vibration, discomfort caused by vehicle vibration can be sufficiently and effectively reduced.

[0022] According to one embodiment of this disclosure, by changing the target rotational speed during power generation to a modified target rotational speed that was used in the past when vibrations were reduced, it becomes unnecessary to set the target rotational speed for each power generation, enabling rapid and efficient control.

[0023] According to one embodiment of this disclosure, the target rotational speed and vehicle speed at which vibrations were reduced in the past are stored in association with each other, and the target rotational speed is changed to a target rotational speed corresponding to the vehicle speed when generating power, thereby reducing vibrations according to the speed and enabling rapid and efficient control.

[0024] According to one embodiment of the present disclosure, by changing the target rotational speed to minimize vibration, the changed target rotational speed is learned as the new target rotational speed, enabling rapid and efficient control.

[0025] According to one embodiment of this disclosure, by making the reference frequency set by the operator, it becomes possible to control the system according to the occupant's preferences. [Brief explanation of the drawing]

[0026] [Figure 1]This is a schematic diagram showing an example of an electric vehicle to which a power generation control method according to one embodiment of the present disclosure is applied. [Figure 2] This is a schematic block diagram showing a first example of a control system in an electric vehicle according to this embodiment. [Figure 3] This is a schematic block diagram showing a second example of a control system in an electric vehicle according to this embodiment. [Figure 4] This flowchart shows an example of a power generation control method in an electric vehicle according to this embodiment. [Figure 5] Figure 4 is a flowchart showing the first example of the process for changing the target engine speed. [Figure 6] Figure 4 is a flowchart showing a second example of the process for changing the target engine speed. [Figure 7] Figure 4 is a flowchart showing a third example of the process for changing the target engine speed. [Figure 8] This is a schematic block diagram showing a third example of a control system in an electric vehicle according to this embodiment. [Figure 9] Figure 8 is a flowchart illustrating the process for changing the target engine speed in the configuration shown. [Modes for carrying out the invention]

[0027] 1. Vehicle Configuration As illustrated in Figure 1, a control unit 100 equipped in a hybrid vehicle 10, which is an example of an electric vehicle according to one embodiment of the present disclosure, performs vehicle control including power generation control, which will be described later. The control unit 100 controls the engine 101, motor 102, generator 103, battery 104, clutch CL, etc. The battery 104 is connected to the generator 103 and motor 102, and stores the power generated by the generator 103 according to the control of the control unit 100, and supplies the stored power to the motor 102.

[0028] Furthermore, if the hybrid vehicle 10 is a plug-in hybrid type, the battery 104 may be charged by power supplied from a household commercial power source or a fast-charging power source at a charging station via an external charging unit. In this case, although not shown, the battery 104 may also supply power to household appliances via an external power supply unit.

[0029] The generator 103 is mechanically connected to the output shaft of the engine 101 via a power transmission path G, and is driven to generate electricity when the engine 101 rotates. The generator 103 can also operate as a motor. Specifically, the generator 103 can act as a starter for starting the engine 101, or it can rotate the engine 102 as a load to use the generated electricity for waste generation.

[0030] The clutch CL mechanically disconnects or connects the transmission of rotational torque from the engine 101 to the gear mechanism 105. When the clutch CL is disconnected, the output shaft of the engine 101 is mechanically connected only to the generator 103. As a result, the driving mode of the hybrid vehicle 10 becomes either EV driving mode or series driving mode. When the clutch CL is connected, the output shaft of the engine 101 is connected not only to the generator 103 but also to the gear mechanism 105, and the gear mechanism 105 can transmit the driving torque of the engine 101 to the drive wheels 106. In this embodiment, the case of EV driving or series driving mode, in which the torque of the engine 101 is absorbed by the generator 103, is illustrated.

[0031] The vibration detector 107 is preferably capable of detecting the magnitude and frequency of vibration acceleration. The vibration detector 107 may be, for example, an acceleration sensor mounted on the vehicle, or various vibration sensors mounted on the vehicle. In addition, the hybrid vehicle 10 may have a microphone to detect the loudness of the engine noise inside the vehicle, in addition to the vibration detector 107. In this case, the control unit 100 can use the vibration detection value and noise detection value to control the engine speed, which will be described later. The user can also operate the operation unit 109 to make various settings (such as setting vibration / noise standard values).

[0032] The control unit 100 is an electronic control unit (ECU) that controls the overall operation of the hybrid vehicle 10. The control unit 100 has a power generation control function that controls the output of the engine 101 based on the vibration detection value (including noise detection value as needed; the same applies hereinafter) detected by the vibration detector 107 when power is generated by the generator 103 and the vehicle speed V. The control unit 100 can also store past target engine speeds where vibration was small in the memory unit 108 and use them for the next power generation.

[0033] The control unit 100 includes a processor such as a CPU (Central Processing Unit), a ROM (Read-only memory) for storing control programs executed by the processor, a RAM (Random access memory) as an operating area for the control program, and an interface section for peripheral circuits. The power generation control method according to this embodiment can be implemented by executing a program on the processor of the control unit 100. The power generation control according to this embodiment will be described in detail below.

[0034] 2. Power generation control 2.1) Configuration The power generation control system according to this embodiment changes the operating point of the engine / generator to reduce unpleasant vibrations, especially when the engine drives the generator to generate power while the vehicle is stopped or moving at low speed. Typically, the power generation control system stores a predetermined map that sets a target engine speed from the required power generation amount, and controls the engine 101 so that its actual rotational speed follows the set target engine speed. Therefore, the power generation control system can change the operating point of the engine 101 or the generator 103 by changing the target engine speed. The power generation control method and system according to this embodiment will be described in detail below.

[0035] As illustrated in Figure 2, the control unit 100 has the functions of a target ENG (engine) rotation speed calculation unit 201 and a target ENG rotation speed control unit 210. The target ENG rotation speed control unit 210 can change the set target ENG rotation speed calculated by the target ENG rotation speed calculation unit 201 during power generation based on the hybrid vehicle state, vehicle speed, vibration detection value, and reference vibration frequency. Based on the changed target ENG rotation speed, the target ENG rotation speed control unit 210 controls the engine 101 so that the actual rotation speed of the engine 101 follows the target rotation speed.

[0036] The power generation control system may have a resetting unit 211 on the output side of the target ENG rotation speed calculation unit 201 equipped with a predetermined map, as illustrated in Figure 3. That is, the resetting unit 211 may change the set target ENG rotation speed output by the target ENG rotation speed calculation unit 201 during power generation according to the hybrid vehicle state, vehicle speed, vibration detection value, and reference vibration frequency.

[0037] The target engine speed calculation unit 201, equipped with a predetermined map, sets the target engine speed to 1500 rpm (revolutions per minute) if the required power generation is 10 kW, and to 2000 rpm if the required power generation is 20 kW. In both cases, the set target engine speed is set to a value that is a predetermined amount higher than the engine speed at which the vehicle's resonant vibration frequency occurs (resonant speed). As a result, the hybrid vehicle 10 avoids the generation of vibrations due to resonance.

[0038] However, such a set target engine speed is likely to cause discomfort to occupants due to vibration or noise, especially when the vehicle is stopped or driving at low speeds. Therefore, according to this embodiment, the resetting unit 211 or the target engine speed control unit 210 changes the set target engine speed within a range between an upper limit that is a predetermined number higher than the set target engine speed and a lower limit that is a predetermined number higher than the resonant speed (preferably within a range between an upper limit that is lower than the set target engine speed and a lower limit that is a predetermined number higher than the resonant speed). By setting a lower limit in this way, vibration due to resonance can be avoided, and by setting an upper limit, noise due to the increase in engine speed can be suppressed. The control by the target engine speed control unit 210 will be described below as an example, but the control by the resetting unit 211 is similar.

[0039] 2.2) Operation The target engine speed control unit 210 determines whether the vehicle is running in series mode, as illustrated in Figure 4 (step 301). If the target engine speed control unit 210 determines that the vehicle is not running in series mode, it returns to step 301. On the other hand, if the target engine speed control unit 210 determines that the vehicle is running in series mode, it sets the vehicle speed V to a predetermined speed V TH The following steps determine whether the vehicle is traveling at a low speed or whether it is stopped (step 302). Note that the predetermined speed V TH The criteria should be such that it determines whether the vehicle is stopped or moving at a slow speed during a traffic jam.

[0040] When the target ENG rotation speed control unit 210 determines that the vehicle is not traveling at a low speed or is not in a stopped state, it returns to step 301 again. On the other hand, when the target ENG rotation speed control unit 210 determines that the vehicle speed is below a predetermined speed V TH it determines whether or not the vibration detection value detected by the vibration detector 107 is equal to or greater than a reference vibration frequency G REF (step 303). The target ENG rotation speed control unit 210 may hold the vehicle speed V at that time in the storage unit 108. Further, when a microphone for detecting vehicle interior noise is equipped, the target ENG rotation speed control unit 210 may determine whether or not the noise level is equal to or greater than a reference value in step 303. Furthermore, when the vibration detector 107 can detect the acceleration of vibration, the target ENG rotation speed control unit 210 may determine whether or not the magnitude of the acceleration of vibration is equal to or greater than a reference value.

[0041] The reference vibration frequency G REF may be a value set at the time of vehicle shipment or a value arbitrarily set by the user. That is, the reference vibration frequency G REF may be set to a value desired by the user as the reference value of the reference vibration frequency G REF , the magnitude of the acceleration of vibration, or the noise level, with the operation of the operation unit 109 installed in the vehicle interior.

[0042] When the target ENG rotation speed control unit 210 determines that it is less than the reference vibration frequency G REF it returns to step 301 again. On the other hand, when the target ENG rotation speed control unit 210 determines that the vibration detection value is equal to or greater than the reference vibration frequency G REF it changes the target ENG rotation speed to a value lower than the set target ENG rotation speed described below and higher than the resonance rotation speed (step 304). This changed target ENG rotation speed may be a value preset at the time of vehicle shipment or a value of the optimum target ENG rotation speed searched as described later at the power generation timing. The target ENG rotation speed control unit 210 can also use the changed target ENG rotation speed for engine control at the next power generation by storing it in the storage unit 108. Hereinafter, an example of the target ENG rotation speed change process (step 304) will be described with reference to FIGS. 5 to 7.

[0043] <Example 1> As illustrated in Figure 5, the target ENG rotation speed control unit 210 changes the target ENG rotation speed set by the target ENG rotation speed calculation unit 201 to the stored modified target ENG rotation speed (step 310). Subsequently, while the engine 101 is rotating at the modified target ENG rotation speed, the target ENG rotation speed control unit 210 determines that the vibration detection value detected by the vibration detector 107 is the reference frequency G REF It is determined whether it is smaller or not (step 311). The target ENG rotation speed control unit 210 determines whether the vibration detection value is the reference frequency G REF If it is determined that the above is true, the currently set target ENG rotation speed is changed by a predetermined number of steps (step 312), and the process returns to vibration determination in step 311. It is desirable that the process of changing the target ENG rotation speed in step 312 be performed within a range between an upper limit lower than the set target ENG rotation speed and a lower limit that is a predetermined number higher than the resonant rotation speed.

[0044] The target engine speed control unit 210 determines when the vibration detection value is the reference frequency G. REF If the value becomes smaller, the target ENG rotation speed at that time is stored in the memory unit 108 (step 313).

[0045] <Example 2> As illustrated in Figure 6, the target ENG rotation speed control unit 210 changes the target ENG rotation speed set by the target ENG rotation speed calculation unit 201 in predetermined steps and generates a modified target ENG rotation speed (step 320). Next, the target ENG rotation speed control unit 210 determines that the vibration detection value detected by the vibration detector 107 while the engine 101 is rotating at the modified target ENG rotation speed corresponds to the reference frequency G REF It is determined whether or not it is less than (step 321). The target ENG rotation speed control unit 210 determines whether the vibration detection value is less than the reference frequency G REF If it is determined that the above is true, the process returns to step 320. The target ENG rotation speed control unit 210 determines that the vibration detection value is the reference frequency G REF If the vibration becomes smaller, the detected vibration value is stored in the memory unit 108 in association with the target engine speed at that time.

[0046] The target engine speed control unit 210 determines the reference frequency G based on the vibration detection value detected by the vibration detector 107. REF If it is determined to be less than the standard frequency G, REF It is determined whether the smaller vibration detection value is the minimum value compared to past vibration detection values ​​(step 322). The target ENG rotation speed control unit 210 determines the reference frequency G REF If the smaller vibration detection value is determined not to be the minimum value compared to past vibration detection values, the process returns to step 320. Meanwhile, if the target ENG rotation speed control unit 210 determines that the current vibration detection value is the minimum, it stores the changed target ENG rotation speed in the storage unit 108 (step 323).

[0047] <Example 3> As illustrated in Figure 7, the target engine speed control unit 210 changes the target engine speed set by the target engine speed calculation unit 201 to the modified target engine speed stored in association with the vehicle speed V (step 330). Next, while the engine 101 is rotating at the modified target engine speed, the target engine speed control unit 210 checks the vibration detection value detected by the vibration detector 107 to determine the reference frequency G. REF It is determined whether it is smaller or smaller (step 331). The target ENG rotation speed control unit 210 determines whether the vibration detection value is the reference frequency G REF If it is determined that the above is true, the currently set target engine speed is changed by a predetermined number of steps (step 332), and the process returns to the vibration determination in step 331. It is desirable that the change process in step 332 be performed within a range between an upper limit lower than the set target engine speed and a lower limit that is a predetermined number higher than the resonant speed.

[0048] On the other hand, the target engine speed control unit 210 determines that the vibration detection value is the reference frequency G. REFIf it is determined that the value is smaller, the target engine speed at that time is stored in the memory unit 108 in association with the vehicle speed at that time (step 333). In addition, in Example 3 illustrated in Figure 7, the target engine speed control unit 210 may execute the minimum value search process (steps 322 and 323) of Example 2 illustrated in Figure 6 following step 331.

[0049] 2.3) Other configurations The power generation control system according to this embodiment can also change the operating point of the engine / generator to reduce unpleasant vibrations, particularly when the engine drives the generator to generate power while the vehicle is stopped or moving at low speed, by using a learning function.

[0050] As illustrated in Figure 8, the target engine speed control unit 210 of the control unit 100 can change the set target engine speed calculated by the target engine speed calculation unit 201 during power generation based on the hybrid vehicle state, vehicle speed, vibration detection value, and reference vibration frequency, using the learning function block 221 and the memory unit 222. The functions of each block are as described above in Figure 8, so they are given the same reference numbers and their explanations are omitted.

[0051] As shown in Figure 9, the target engine speed control unit 210 determines the vibration detection value to be the reference frequency G. REF If it is determined that the above conditions are met (YES in step 303), the target ENG rotation speed is changed based on the learning results held in the learning block 221 and the memory unit 222 (step 340).

[0052] Next, the target ENG rotation speed control unit 210 determines that the vibration detection value detected by the vibration detector 107 while the engine 101 is rotating at the changed target ENG rotation speed corresponds to the reference frequency G. REF It is determined whether it is smaller or not (step 341). The target ENG rotation speed control unit 210 determines whether the vibration detection value is the reference frequency G REFIf the above conditions are met, the currently set target engine speed is changed by a predetermined number of steps (step 342), and the process returns to the vibration determination in step 341. It is desirable that the change process in step 342 be performed within a range between an upper limit lower than the set target engine speed and a lower limit a predetermined number higher than the resonant speed.

[0053] Next, the target ENG rotation speed control unit 210 sets the reference frequency G REF Step 343 determines whether the smaller vibration detection value is the minimum value compared to past vibration detection values. If the target ENG rotation speed control unit 210 determines that the current vibration detection value is the minimum, it learns the changed target ENG rotation speed at that time and stores the learning result in the storage unit 222 (Step 344).

[0054] 3. Effects As described above, according to this embodiment, the target ENG rotation speed control unit 210 or the resetting unit 211 changes the target ENG rotation speed within a predetermined range so that the vibration (or vibration and noise) during power generation is smaller than a reference value. This reduces the discomfort of vibration experienced by the occupants when the engine drives the generator for power generation. [Explanation of symbols]

[0055] 10 Hybrid Vehicles 100 Control Unit 101 Engine 102 Motor 103 Generator 104 batteries 105 Gear mechanism 106 Drive wheels 107 Vibration detector 108 Storage section 201 Target engine speed calculation unit 210 Target Engine Speed ​​Control Unit 211 Reset Section 221 Learning Function Blocks 222 Storage section

Claims

1. A control system for an electric vehicle, comprising an engine, a power transmission path for transmitting power from the engine, and a generator that receives power from the engine via the power transmission path and generates electricity, A vibration detector that detects vehicle vibrations, A control unit that controls the engine by setting a target rotational speed of the engine according to the target amount of power generated during the aforementioned power generation, Includes, A control system for an electric vehicle, characterized in that, when generating power, if the vibration of the vehicle exceeds a predetermined reference frequency, the control unit changes the target rotational speed so that the vibration detected by the vibration detector becomes smaller than the reference frequency.

2. The control system for an electric vehicle according to claim 1, characterized in that the power transmission path constantly transmits power from the engine to the generator.

3. The control system for an electric vehicle according to claim 1 or 2, characterized in that the control unit changes the target rotation speed when the vehicle's speed is lower than a predetermined reference speed.

4. The control system for an electric vehicle according to claim 1 or 2, characterized in that the control unit changes the target rotational speed to a rotational speed higher than the rotational speed of the engine corresponding to the resonant vibration frequency of the vehicle.

5. The vehicle further includes a microphone for detecting the noise level inside the vehicle associated with the rotation of the engine, The control system for an electric vehicle according to claim 1 or 2, characterized in that the control unit changes the target rotational speed so that the noise level caused by the rotation of the engine is lower than a predetermined standard.

6. The control system for an electric vehicle according to claim 1 or 2, characterized in that the control unit changes the target rotational speed so that the vibration detected by the vibration detector is minimized.

7. It has a storage unit that stores past modified target rotation speeds that resulted in vibrations smaller than the reference vibration value, corresponding to the aforementioned target rotation speed. The control system for an electric vehicle according to claim 1 or 2, characterized in that the control unit changes the target rotation speed to the modified target rotation speed stored in the storage unit when generating power.

8. The storage unit stores the target rotational speed and the vehicle's speed when the target rotational speed is reached in association with each other. The control system for an electric vehicle according to claim 7, characterized in that the control unit changes the target rotational speed to a modified target rotational speed corresponding to the vehicle's speed during power generation.

9. The control system for an electric vehicle according to claim 1 or 2, characterized in that when the control unit changes the target rotational speed so that the vibration detected by the vibration detector is minimized, the changed target rotational speed is learned as the modified target rotational speed, and the target rotational speed is changed to the learned modified target rotational speed when generating power.

10. The electric vehicle control system according to claim 1 or 2, further comprising a frequency setting unit that allows the operator to set the aforementioned reference frequency.

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