JP5857472B2 - Electric motor control method - Google Patents

Description

  The present invention relates to an electric motor control method, and more particularly to an electric motor control method for controlling an electric input so that an actual output rotational speed and an output torque coincide with a required rotational speed and a required torque that are required operating points.

  In hybrid vehicles, an engine and an electric motor are mounted as driving sources, and driving by the engine can be assisted by the electric motor or can be driven by the electric motor alone. In general, a three-phase AC motor is used as the motor, and the output rotational speed and the output torque are variably controlled by controlling the electric input. The electric input is often controlled by a voltage type pulse width modulation control method in which the effective value is variably controlled by controlling the duty ratio of the rectangular wave voltage within one cycle of the carrier frequency by an inverter device.

  For example, Non-Patent Document 1 discloses a technical example of a hybrid vehicle motor using an engine as a main power and a motor as an auxiliary power. This motor is a DC brushless motor and has a function of generating power by driving from the engine and an energy regeneration function during vehicle braking in addition to the function of an auxiliary power source. And in order to implement | achieve the function as a vehicle drive system, drive control is carried out at the operating point which corresponds to the rotation speed and torque which are requested | required from a system control part. The high efficiency region of the motor is set slightly higher than the actual use region where there are many opportunities for actual operation.

  Patent Document 1 discloses a motor control system for a vehicle that can accurately generate torque requested by a driver. This motor control system includes an AC electric motor, a DC power supply, and a control unit, and is effective to generate a torque current and a magnetic flux current based on the torque command, and to accurately satisfy the torque command. A space vector pulse width modulation unit for supplying a multiphase voltage signal to the motor. Further, in the dependent claims and the embodiments, a three-phase induction motor is exemplified as an AC electric motor, and an IGBT device (which can be interpreted as a kind of inverter device that performs voltage-type pulse width modulation control) is used as a space vector pulse width modulation unit. Is illustrated.

JP 2002-142500 A

Akiyoshi Shimada “Honda's development of hybrid and fuel cell motors”, 22nd Motor Technology Forum 7th handout, 2003, organized by Japan Management Association

  By the way, in the techniques of Non-Patent Document 1 and Patent Document 1, an on-vehicle electric motor (motor) has a required operating point required from the outside such as a system control unit or a driver, that is, an output operating point that matches the required rotational speed and required torque. Operate. In general, the output range of an electric motor is set in consideration of the maximum torque required when starting a vehicle or climbing a steep slope, but the torque required for normal flat land travel is the maximum torque. Considerably smaller than. For this reason, the high efficiency region of the electric motor tends to shift to a relatively large torque side depending on the maximum torque, and the operating point at the time of traveling on flat ground deviates to a smaller torque side than the high efficiency region. That is, there are many cases where the operation is performed in a region where the efficiency is low, and a lot of loss is generated, so that the fuel consumption of the vehicle is lowered. Therefore, in order to improve fuel efficiency, it is important to improve efficiency at low loads that occupy much of the operating time and require a relatively small torque.

  The above-mentioned problems are not limited to in-vehicle driving motors, and are common to electric motors that operate at a low load during normal operation with respect to setting of an output range, even if they are used for different purposes. The above-mentioned problems are as follows. It is not limited to the type of power source of the motor, that is, direct current, single-phase alternating current or three-phase alternating current, nor is it limited to a synchronous type or induction type, nor is it limited to differences in control method or internal structure. It is common.

  The present invention has been made in view of the above-mentioned problems of the background art, and an object to be solved is to provide a method for controlling an electric motor that can improve efficiency at a low load as compared with the prior art.

The invention of the electric motor control method according to claim 1 for solving the above-described problem is based on the variable required rotational speed and the required torque that are the required operating points, and the required output rotational speed and output torque that are the actual output operating points. An electric motor control method for controlling an electric input so as to coincide with an operating point, wherein the output rotation speed is continuously matched with the requested rotation speed over a predetermined unit time, and the condition of the requested rotation speed is satisfied. The instantaneous torque that is actually output by the motor is changed by combining the maximum efficiency torque value, which is the torque value at which the highest efficiency is obtained, and the zero torque value when the electrical input is lost at the time ratio within the unit time. is allowed to control the electrical input to the output torque required by the unit time average value through the time of the instantaneous torque coincides with the required torque, the While the rotational speed and the required torque are constant, the unit time is maintained substantially constant, and at least one of the time ratio, the maximum efficiency torque value, and the zero torque value for each unit time as time elapses. Slightly change or swing.

According to a second aspect of the present invention, in the first aspect, the unit time is slightly changed or oscillated with time.

According to a third aspect of the present invention , the electric input is set so that the output rotational speed and the output torque, which are the actual output operating points, coincide with the required operating point based on the variable required rotational speed and the required torque that are the required operating points. A control method for an electric motor to be controlled, wherein the output rotational speed is made to coincide with the required rotational speed continuously over a predetermined unit time, and at the torque value at which the highest efficiency is obtained under the required rotational speed conditions. The instantaneous torque actually output by the motor is changed by combining a certain maximum efficiency torque value and the zero torque value when the electric input is lost at a time ratio within the unit time, and the unit time of the instantaneous torque is changed. The electrical input is controlled so that the output torque obtained by the time average value passed through matches the required torque, and the required rotational speed and the required torque are constant. There between, while maintaining the unit time a substantially constant, slightly changing the unit time with time, or to swing.

According to a fourth aspect of the present invention, in any one of the first to third aspects, the electric input control method is a voltage type pulse width modulation control that variably controls the duty ratio of the rectangular wave voltage within a repeated carrier cycle. The unit time is two times or more of the carrier cycle, and is set according to the required rotation speed and the required torque.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, a torque transition absorption device that absorbs the transition of the instantaneous torque and suppresses the instantaneous change is provided on the output side of the electric motor.

Invention, in any one of claims 1 to 5, when the required rotational speed and the requested torque satisfies a predetermined condition, the output rotation speed to the required rotational speed through the unit time according to claim 6 Continuously changing the instantaneous torque including the high-efficiency torque value, and when the predetermined condition is not satisfied, the output rotational speed continuously matches the requested rotational speed throughout the unit time. And the instantaneous torque is continuously matched with the required torque.

According to a seventh aspect of the present invention, in the sixth aspect , the predetermined condition is a condition in which a time change rate of the required rotational speed and the required torque is equal to or less than a predetermined threshold value.

The invention according to claim 8, in any one of claims 1 to 7, wherein the electric motor is used to drive source is mounted on a hybrid vehicle or an electric vehicle.

In the invention of the electric motor control method according to claim 1 and claim 3 , the output rotational speed is made to coincide with the required rotational speed continuously throughout the unit time to be constant, the output torque is not constant, and the maximum efficiency torque value and zero torque are set constant . The instantaneous torque is changed by combining the value with the time ratio within the unit time. At this time, the efficiency in the time zone in which the instantaneous torque is the maximum efficiency torque value is literally the maximum efficiency, and the loss is small in the time zone in which the instantaneous torque is the zero torque value. Then, the electric input is controlled so that the output torque obtained by the time average value of the instantaneous torque matches the required torque. On the other hand, in the conventional control technique, the instantaneous torque is continuously matched with the required torque throughout the unit time and kept constant. Therefore, the average efficiency over the unit time in the present invention is remarkably improved as compared with the efficiency of the conventional control technique, and this effect occurs at a low load that occupies much of the operation time. In addition, this effect is not limited to the type of power source of the motor, that is, DC, single-phase AC or three-phase AC, and is not limited to a synchronous type or an induction type. It occurs without being limited to the difference.

Further, in the inventions according to claims 1 and 3 , since the unit time is maintained substantially constant while the required rotational speed and the required torque are constant, the control is simplified.

Further, according to the first aspect of the invention, at least one of the time ratio, the maximum efficiency torque value, and the zero torque value is slightly changed or oscillated for each unit time as time elapses. In the inventions according to claims 2 and 3 , the unit time is slightly changed or oscillated with the passage of time. Here, “oscillation” means that the control value of each time is appropriately varied up and down around a predetermined target value, and the average control value obtained by averaging the control values of each time converges to the target value when a long time has elapsed. Means to control. Further, the control other than “oscillation” is “change”, and for example, the control gradually increases the control value of each time. As described above, by slightly changing or swinging at least one of the time ratio, the maximum efficiency torque value, the zero torque value, and the unit time, it is possible to prevent generation of harmful resonance phenomenon, vibration, noise, and the like. If these control amounts are kept completely constant, a harmful phenomenon may occur due to the approximation of the frequency obtained by the reciprocal of unit time and the natural frequency of a specific part of the motor.

In the invention according to claim 4, the electric input control method is a voltage type pulse width modulation control method, the unit time is set to be twice or more the carrier cycle, and is set according to the required rotation speed and the required torque. The present invention can be implemented with a configuration in which an electric input is controlled by a voltage type pulse width modulation control system using an inverter device, for example, and an instantaneous torque can be easily generated by variably controlling a duty ratio of a rectangular wave voltage input to an electric motor. It can be changed.
In the invention which concerns on Claim 5 , the torque transition absorption apparatus which absorbs the transition of an instantaneous torque and suppresses an instantaneous change is provided in the output side of an electric motor. Thereby, generation | occurrence | production of a harmful resonance phenomenon, a vibration, a noise, etc. can be prevented. Also, the output torque is smoothed compared to the case where no torque transition absorber is provided.

In the invention according to claim 6 , the control for changing the instantaneous torque including the high-efficiency torque value according to the conditions of the required rotational speed and the required torque, and the conventional control for continuously matching the instantaneous torque with the required torque, Select. Further, in the invention according to claim 7 , when the condition that the time change rate of the required rotational speed and the required torque is equal to or less than a predetermined threshold is satisfied, the control for changing the instantaneous torque including the high efficiency torque value is performed. carry out. That is, the control for changing the instantaneous torque is performed when the required rotation speed and the required torque change relatively slowly, and the control for changing the instantaneous torque is interrupted in a transition period in which at least one of them changes rapidly. As a result, it is possible to avoid the possibility that an appropriate unit time cannot be secured during the transition period, and it is possible to stably control the operation of the electric motor.

In the invention according to claim 8 , since the electric motor is mounted on a hybrid vehicle or an electric vehicle and used as a travel drive source, the efficiency at the time of low load such as traveling on flat ground can be improved. Thereby, the fuel consumption of the vehicle is improved.

It is a figure explaining the example of the apparatus structure which performs the control method of the electric motor of embodiment. (1) shows the output characteristics of the motor and the running performance diagram of the vehicle, and (2) shows the efficiency map of the motor and the running center of gravity of the vehicle. It is the figure which illustrated the relationship between the running pattern of a vehicle, and the output operation point of an electric motor, (1) shows the temporal change of the torque output from the vehicle speed and electric motor of a vehicle, (2) is on the output characteristic of an electric motor. The change of the position of the output operation point is shown. It is a figure explaining the control method of the electric motor of embodiment, (1) is a figure explaining this control method on the output characteristic of an electric motor, (2) is a time waveform of instantaneous torque when this control method is implemented. is there. It is a figure explaining the method of the rectangular wave voltage control of the electric motor by an inverter apparatus with the electric motor control method of embodiment, (1) is the time waveform of instantaneous torque, (2) is the time waveform of rectangular wave voltage, (3 ) Shows a time waveform of current. It is a figure explaining the control method which makes an output torque correspond to a required torque continuously when a predetermined condition is not satisfy | filled with the control method of the electric motor of embodiment, (1) is a time waveform of an instantaneous torque, (2) Represents a time waveform of a rectangular wave voltage, and (3) represents a time waveform of a current. It is a figure explaining the control processing flow at the time of performing the control method of the electric motor of embodiment. It is a figure explaining the principle of the apparatus structure which prevents that a harmful resonance phenomenon, a vibration, noise, etc. which are harmful to an electric motor generate | occur | produce.

  A method for controlling an electric motor according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram illustrating an example of a device configuration that performs a method for controlling an electric motor according to an embodiment. The arrows in the figure indicate the flow of power and information. The electric motor 1 is mounted on the vehicle 9 as an auxiliary travel drive source. The vehicle 9 is a hybrid vehicle on which an engine (not shown) is also mounted as a main driving source. However, the vehicle 9 is not limited to this, and may be any of an electric vehicle and a fuel cell vehicle that use only the electric motor 1 as a travel drive source. The motor 1 is preferably a three-phase synchronous motor or a three-phase induction motor, and is not limited to this.

  As a power source for the electric motor 1, a DC power source 2 and an inverter device 3 are used. As the DC power source 2, a battery, a fuel cell, or the like can be used. The inverter device 3 has a built-in power element, and controls the duty ratio within one cycle of the carrier frequency based on a control signal Ct from an electric motor ECU 4 described later. As a result, the rectangular wave voltage V after the on / off control of the DC voltage Vdc of the DC power supply 2 is applied to the electric motor 1. As the inverter device 3, a known voltage-type pulse width modulation control system device can be used.

  An electric motor ECU 4 is used as a control device for the electric motor 1. The electric motor ECU 4 is an electronic control device that incorporates a microcomputer and operates by software. As shown in FIG. 1, the electric motor ECU 4 acquires information on the vehicle state such as accelerator information Ac, brake information Br, rudder angle information St, and vehicle speed v from the vehicle ECU 5. The electric motor ECU 4 determines the required rotational speed Nr and the required torque Tr that are required operating points based on these pieces of information. The requested operation point can be held in the storage unit of the electric motor ECU 4 as a data map having various information as parameters, for example. In this case, the electric motor ECU 4 can determine the required rotational speed Nr and the required torque Tr described above by obtaining and reading the required operating point corresponding to the acquired information on the data map.

  Furthermore, the motor ECU 4 sends a control signal Ct to the inverter device 3 so as to realize the required operating point, and controls the operation of the motor 1 via the inverter device 3. The control signal Ct includes information on the current application timing for realizing the required rotational speed Nr and information on the current value necessary for generating the required torque Tr or information on the voltage value derived from the current value. .

  The vehicle ECU 5 is also an electronic control device, and controls the overall traveling of the vehicle 9 as a host device of the electric motor ECU 4. The vehicle ECU 5 acquires information such as the accelerator information Ac, the brake information Br, the steering angle information St, and the vehicle speed v described above from sensors (not shown). The vehicle ECU 5 also exchanges information with an unillustrated engine ECU to support engine control by the engine ECU, and further controls the overall traveling in cooperation with an unillustrated transmission ECU, brake ECU, and the like.

  When the inverter device 3 applies the rectangular wave voltage V under the control of the electric motor ECU 4, the electric motor 1 operates and the vehicle 9 travels. Information on the rotation angle information θ of the rotor of the electric motor 1 and information on the internal temperature tmp1 is fed back to the electric motor ECU 4. Further, the information about the internal temperature tmp2 of the device and the current I flowing through the electric motor 1 is fed back from the inverter device 3 to the electric motor ECU 4.

  Next, the output characteristics and efficiency map of the electric motor 1, the travel performance diagram of the vehicle 9, and the travel center of gravity will be described. 2 shows an output characteristic of the electric motor 1 and a travel performance diagram of the vehicle 9, and (2) shows an efficiency map of the electric motor 1 and a travel center of gravity of the vehicle 9. FIG. In both (1) and (2), the horizontal axis represents the rotational speed N of the electric motor 1, and the vertical axis represents the output torque T. As shown in the figure, the electric motor 1 has a range indicated by a medium thick line between the rotational speed N = 0 to the maximum rotational speed Nmax and the torque T = 0 to the maximum torque Tmax as an output range. Although not shown, the electric motor 1 has an energy regeneration function when the vehicle 9 is braked, and generates electric power by inputting a braking torque Tx (hereinafter, described as a negative value for convenience). Can also occur.

  In (1) of FIG. 2, the road gradient K is used as a parameter as the road running load of the vehicle 9, and each running performance line at the road gradient K = 0%, 5%, 10%, and 30% is indicated by a thin line. Yes. The running performance line has a characteristic of increasing to the right where the torque T increases as the rotational speed N increases when the road surface gradient K is constant. Further, as the road surface gradient K increases, the entire travel performance line shifts to the large torque T side (upward in the figure), and in the example in the figure, the travel performance line approaches the maximum torque Tmax when the road surface gradient K = 30%.

  In (2) of FIG. 2, the efficiency η of the electric motor 1 is used as a parameter, and the isoefficiency lines at the efficiency η = 85%, 90%, and 95% are indicated by thin lines. Further, the maximum efficiency line Emax connecting the operating points at which the efficiency η at each rotation speed N is maximum is indicated by a bold line. As shown in the figure, the maximum efficiency line Emax has a mountain-shaped curve characteristic in which the torque T is the largest at the center rotational speed N. Here, the region below the maximum efficiency line Emax is a region where the torque T actually output is smaller than the torque that generates the maximum efficiency, and is referred to as a low load region AL for convenience.

  In addition, the high-speed cruise center of gravity point GH is located on the high speed side of the equi-efficiency line of efficiency η = 85% in FIG. 2 (2), and the city center gravity center point GL is located on the low speed side. The high-speed cruise center-of-gravity point GH indicates an average operating point of the electric motor 1 when the vehicle 9 travels on a highway or the like. A city center of gravity point GL indicates an average operating point of the electric motor 1 when the vehicle 9 travels on a general road in the city area. Both the high-speed cruise center-of-gravity point GH and the city-running center-of-gravity point GL are in the low load area AL. That is, in the electric motor 1 mounted on the vehicle 9, the operation time occupies most of the operation time in the low load area AL.

  Next, the relationship between the traveling pattern of the vehicle 9 and the actual output operating point of the electric motor 1 will be described by way of example. The output operating point means the rotational speed N and torque T actually output from the electric motor 1, and is indicated by one point in the output characteristic diagram shown in FIG. FIG. 3 is a diagram illustrating the relationship between the travel pattern of the vehicle 9 and the output operation point of the electric motor 1, and (1) shows the temporal change in the vehicle speed v of the vehicle 9 and the torque T output from the electric motor 1. , (2) shows the change in the position of the output operating point on the output characteristics of the electric motor 1. Note that FIG. 3 is an example, and an actual traveling pattern naturally changes depending on each traveling.

  In FIG. 3 (1), the electric motor 1 is started at time t1, torque T is generated, and the vehicle 9 starts. The torque T gradually increases from time t1 through time t2 to time t3, and the vehicle speed v increases accordingly. Between time t3 and time t4, the torque T becomes maximum and the vehicle speed v is accelerated rapidly. After the time t4, when the torque T is gradually decreased through the time t5 and until the time t6, the vehicle speed v gradually decreases and reaches the maximum vehicle speed within the range illustrated at the time t6. From time t6 to time t7, the maximum vehicle speed is maintained by a slight torque T. When the torque T disappears at time t7, the vehicle 9 becomes inertial running, and the vehicle speed v shows a slightly decreasing tendency.

  When the brake pedal is depressed at time t8, the braking torque T is distributed to the hydraulic brake and the regeneration function of the electric motor 1. Thereby, the electric motor 1 operates as a generator when the regenerative torque Tx is input. From time t8 to time t9, the braking torque T is set to the maximum value in the range shown in the figure, the vehicle speed v decreases after time t9, and the braking torque T gradually decreases from time t10 to time t11. At time t11, the vehicle speed v becomes 0 and the vehicle 9 stops.

  The change of the output operating point of the electric motor 1 in the above traveling pattern is indicated by a thick line in (2) of FIG. 3 and the times t1 to t11 are also shown. In (2) of FIG. 3, the region where the torque T is positive is a power running region where the motor 1 outputs the torque T, and the region where the torque T is negative (regenerative torque Tx) is input to the motor 1 with the regenerative torque Tx. It is a regenerative area where electricity is generated. As shown in the figure, the output operating point moves in the power running region and in the low load region AL where the torque T is smaller than the maximum efficiency line Emax during the time t1 to t2 and the time t4 to t8. Further, during the time t2 to t4, the output operating point moves in the power running region and in a region where the torque T is larger than the maximum efficiency line Emax. Between time t8 and t11, the output operating point is moving within the regeneration zone.

  Next, a method for controlling the electric motor according to the embodiment will be described. The method for controlling the electric motor according to the embodiment can be performed when the required operation point required for the electric motor 1 is in the low load region AL. Therefore, in the example of FIG. 3, it can be performed between time t1 and t2 and between time t4 and t8. 4A and 4B are diagrams for explaining the control method for the electric motor according to the embodiment. FIG. 4A is a diagram for explaining the control method on the output characteristics of the electric motor 1, and FIG. 4B is an instantaneous view when the control method is executed. It is a time waveform of torque T (t) (note that the control method in the power running region is explained, but the same applies to the regeneration region).

  In (1) of FIG. 4, the required operating point D is in the low load region AL, and the required rotational speed Nr = n1 and the required torque Tr = Tn1. At this time, the maximum efficiency torque value Tn1e-max, which is the torque value at which the highest efficiency is obtained under the condition of the required rotation speed Nr = n1, is from the maximum efficiency point Dmax that is the rotation speed n1 on the maximum efficiency line Emax. Desired. Further, the maximum efficiency torque value Tn1e-max is larger than the required torque Tr = Tn1.

  In the motor control method of the embodiment, the output speed is continuously matched with the required speed Nr = n1 through the unit time tA, and the maximum efficiency torque value Tn1e-max and the zero torque value when the electric input is lost are obtained. In combination with the time ratio Rt within the unit time tA, the instantaneous torque T (t) is changed as shown in (2) of FIG. More specifically, the maximum efficiency torque value Tn1e-max is generated by applying a voltage to the motor 1 during the energization time tB from the time t21 to t22 during the unit time tA from the time t21 to t23. A voltage is not applied between t22 and t23, and a zero torque value is set.

  Further, the voltage is controlled so that the effective output torque T obtained by the time average value of the instantaneous torque T (t) through the unit time tA satisfies the condition that the required torque Tr = Tn1. The time ratio Rt that satisfies this condition is obtained by the time ratio Rt = (tB / tA) = (Tn1 / Tn1e−max). Since the change in the instantaneous torque T (t) due to the voltage control is steep, it is possible to ignore the rise and fall time delays.

  In the case where the required torque Tr is in a region on the side larger than the maximum efficiency line Emax, even if the instantaneous torque T (t) is changed by combining the maximum efficiency torque value Tn1e-max and the zero torque value in a time ratio, the time The output torque obtained by the average value cannot be matched with the required torque Tr.

  Next, a method of controlling the rectangular wave voltage V of the electric motor 1 by the voltage type pulse width modulation control type inverter device 3 will be described. FIG. 5 is a diagram for explaining a method of controlling the rectangular wave voltage V of the electric motor 1 by the inverter device 3 in the electric motor control method of the embodiment. (1) is a time waveform of the instantaneous torque T (t); ) Shows the time waveform of the rectangular wave voltage V, and (3) shows the time waveform of the current I. Each horizontal axis of (1) to (3) is a common time t. In addition, (1) of FIG. 5 is a waveform which expanded the range from the time t21 to t23 of (2) of FIG.

  In the present embodiment, the inverter device 3 variably controls the duty ratio Rd of the rectangular wave voltage V within the repeated carrier cycle tC. Specifically, the inverter device 3 generates the rectangular wave voltage V at a certain duty ratio Rd during the energization time tB from the time t21 to t22 on the front side within the unit time tA shown in (2) of FIG. The rectangular wave voltage V is not generated between the rear times t22 to t23. Here, the peak value of the rectangular wave voltage V is the DC voltage Vdc of the DC power supply 4. Further, when the time width during which the DC voltage Vdc of the rectangular wave voltage V is generated, that is, the on-duty time td, the duty ratio Rd = (td / tC) during the energization time tB is obtained. It is the effective value V2 of the rectangular wave voltage V through the energization time tB, and becomes the effective value V1 (V1 <V2) of the rectangular wave voltage V through the unit time tA.

  When the rectangular wave voltage V shown in (2) of FIG. 5 is applied, the electric current I shown in (3) of FIG. The waveform of the current I is a direct current waveform including a ripple during the energization time tB, and is substantially zero between the times t22 and t23 when the rectangular wave voltage V is not applied. The effective value I2 of the current I through the energization time tB is the effective value I1 (I1 <I2) of the current I through the unit time tA. The average output torque T obtained with the effective value I1 of the current I matches the required torque Tr = Tn1.

  In the voltage-type pulse width modulation control type inverter device 3, the unit time tA needs to be at least twice the carrier cycle tC at the shortest in order to separately provide the energization time tB and the non-energization time zone. In the example of FIG. 5, the unit time tA is nine times the carrier period tC. Further, if the unit time tA is set long, there is a possibility that the passenger of the vehicle 9 may feel uncomfortable or the vehicle 9 may not run smoothly, so the maximum value is limited. The unit time tA is preferably set according to the required rotational speed Nr and the required torque Tr, and is preferably maintained substantially constant while the required rotational speed Nr and the required torque Tr are constant. The unit time tA can be determined using, for example, a data map or a calculation formula that uses the required rotational speed Nr and the required torque Tr as parameters in the electric motor ECU 5.

  Next, a control method for interrupting and replacing the control for changing the instantaneous torque T (t) including the maximum efficiency torque value Tn1e-max when the predetermined condition is not satisfied will be described in comparison with FIG. . FIG. 6 is a diagram for explaining a control method for continuously matching the instantaneous torque with the required torque when the predetermined condition is not satisfied in the motor control method according to the embodiment. 6A shows a time waveform of the instantaneous torque T (t), FIG. 6B shows a time waveform of the rectangular wave voltage V, and FIG. 6C shows a time waveform of the current I. The same times t21 to t23 as in FIG. The time range up to is illustrated. The predetermined condition is a condition in which the time change rate of the required rotational speed Nr and the required torque Tr is equal to or less than a predetermined threshold, and it can be determined that the required operating point is in a transitional period in which the required operating point rapidly changes when this is not satisfied. .

  In the control method performed in place of the transition period, the output rotational speed is made to coincide with the required rotational speed Nr = n1 continuously throughout the unit time tA, and the required torque Tr = Tn1 as shown in (1) of FIG. The instantaneous torque T (t) is continuously made constant to keep constant. The inverter device 3 continuously generates the rectangular wave voltage V at a constant duty ratio within the unit time tA as shown in (2) of FIG. When this rectangular wave voltage V is applied, a current I shown in (3) of FIG. The waveform of the current I becomes a direct current waveform including a ripple through the unit time tA. The effective value V1 of the voltage V through the unit time tA becomes the effective value I1 of the current I, which matches the case of FIG. The control method shown in FIG. 6 is almost the same as the control method conventionally performed.

  Next, a control processing flow when performing the motor control method of the embodiment will be described with reference to FIG. The control process flow shown in FIG. 7 is executed and controlled by the electric motor ECU 4.

  In step S1 of FIG. 7, the electric motor ECU 4 first reads the required rotational speed Nr and the required torque Tr that are the required operating points. Next, in step S2, it is determined whether or not the requested operating point is within the low load area AL. If not, the process proceeds to step S6. When the requested operating point is within the low load area AL, the process proceeds to step S3. If the timer has not timed the elapsed time t, the timer is activated to start the elapsed time t. In a succeeding step S4, it is determined whether or not the elapsed time t has reached a predetermined time t0. If not, the process proceeds to step S6.

  If the elapsed time t has reached the predetermined time t0, the process proceeds to step S5, and it is determined whether or not the amount of change of the required rotation speed Nr and the required torque Tr from the time before the predetermined time t0 is equal to or less than a threshold value. When the amount of change is larger than the threshold value, it can be determined that the requested operating point is in a transition period in which the change is abrupt, and the process proceeds to step S6. When the amount of change is less than or equal to the threshold value, it can be determined that the requested operating point is changing constantly or gently, and the process proceeds to step S7. It should be noted that the threshold value indicates whether the behavior of the vehicle 9 can be maintained smoothly by switching the execution and interruption of the control in step S7, whether the effect of the control in step S7 can be expected, and the response by torque control. The delay time can be determined appropriately.

  Step S6 is the step S2 when the requested operating point is a high load that is not in the low load region AL, the step S4 is the time when the predetermined time t0 does not elapse and the change of the requested operating point cannot be determined, and the step S6 It is executed during the transition period when the operating point is changing rapidly. In step S6, the control calculation for keeping the instantaneous torque T (t) described in FIG. 6 constant is performed. On the other hand, step S7 is executed when the required operating point changes at S6 in a constant or slow manner. In step S7, calculation of control for changing the instantaneous torque T (t) described in FIG. 5 is performed. Step S6 and step S7 merge at step S8, and the motor ECU 4 sends a control signal Ct to the inverter device 3 based on the calculation result. The inverter device 3 applies the rectangular wave voltage V shown in FIG. 5 or 6 to the electric motor 1 based on the control signal Ct. In step S8, one cycle of the motor 1 control is completed, the process returns to step S1, and is repeated thereafter.

  According to the motor control method of the embodiment, when the required torque Tr = Tn1 is relatively small, a high efficiency torque value exists at low load, and the instantaneous torque T (t) is appropriately changed including the high efficiency torque value. The average efficiency over the unit time tA is improved as compared with the conventional case due to the effect of high efficiency in the high efficiency torque value. In particular, as shown in FIG. 5, the instantaneous torque T (t) is changed by combining the maximum efficiency torque value Tn1e-max and the zero torque value at a time ratio within the unit time tA. At this time, the efficiency in the time zone in which the instantaneous torque T (t) is the maximum efficiency torque value Tn1e-max is literally the maximum efficiency, and the loss is small in the time zone in which the instantaneous torque T (t) is the zero torque value. . Therefore, the average efficiency over the unit time tA is markedly improved compared to the efficiency of the conventional control technique (FIG. 6) that continuously matches the instantaneous torque T (t) with the required torque Tr over the unit time tA. This effect occurs at low load, which occupies most of the operating time.

  Further, the electric input control method is a voltage type pulse width modulation control method by the inverter device 3, and the instantaneous torque T (t) can be easily controlled by variably controlling the duty ratio Rd of the rectangular wave voltage V. It can be changed. Furthermore, since the unit time tA is maintained substantially constant while the required rotational speed Nr and the required torque Tr are constant, the control is simplified. Further, when the time change rate of the required rotational speed Nr and the required torque Tr is larger than a predetermined threshold, the control for changing the instantaneous torque including the high efficiency torque value is interrupted. As a result, it is possible to avoid the possibility that an appropriate unit time tA cannot be secured during the transition period, and the operation of the electric motor 1 can be stably controlled.

  Furthermore, since the electric motor 1 is mounted on the vehicle 9 and used as a travel drive source, it is possible to improve the efficiency during low loads such as traveling on flat ground. Thereby, the fuel consumption of the vehicle 9 is improved.

  Next, a method for preventing the occurrence of harmful resonance phenomenon, vibration and noise will be described. FIG. 8 is a diagram for explaining in principle a device configuration that prevents the generation of harmful resonance phenomena, vibrations, noises, and the like that are harmful to the electric motor 1. The same control described in FIGS. 2 to 7 is performed on the electric motor 1 of FIG. 8 using the same configuration as that of FIG. In the vehicle 9, the output shaft 11 of the electric motor 1 is directly connected to the speed reducer 6, and the torque transition absorbing device 7 is provided on the output shaft 11. As the torque transition absorber 7, for example, a conventional damper device provided on an output shaft of an in-vehicle engine and including an inertia mass and a buffer spring can be used.

  In the configuration of FIG. 8, a torque transition absorption device 7 that absorbs the transition of the instantaneous torque T (t) and suppresses the instantaneous change is provided on the output side of the electric motor 1. Therefore, even if the frequency obtained by the reciprocal of the unit time tA approximates a specific part of the electric motor 1, for example, the natural frequency of the output shaft 11, a harmful resonance phenomenon, vibration and noise are generated by the torque transition absorber 7. Can be prevented. Further, the torque T input to the speed reducer 6 is smoothed as compared with the case where the torque transition absorber 7 is not provided.

  Further, there is a control method from the electric motor ECU 4 that prevents the occurrence of harmful resonance phenomena, vibrations and noises in place of the torque transition absorber 7 or in combination with the torque transition absorber 7. That is, by controlling from the electric motor ECU 4, at least one of the time ratio Rt (= tB / tA), the maximum efficiency torque value Tn1e-max, the zero torque value, and the unit time tA is slightly changed or oscillated. Can prevent the occurrence of unusual resonance phenomenon, vibration and noise. That is, by changing or swinging them, the sharpness of the excitation force characteristics can be dulled, so that the resonance phenomenon is less likely to occur. If these control amounts are kept completely constant, a harmful phenomenon may occur due to the approximation of the frequency obtained by the reciprocal of the unit time tA and the natural frequency of a specific part of the electric motor 1.

  In the embodiment, the maximum efficiency torque value Tn1e-max and the zero torque value are combined at a time ratio and the instantaneous torque T (t) is changed in two stages. However, the present invention is not limited to this. That is, even if it is not necessarily the maximum efficiency torque value Tn1e-max, it includes a high efficiency torque value that can obtain higher efficiency than that obtained by continuously outputting the required torque Tr under the condition of the required rotational speed Nr. If changed, the effect will occur. Moreover, you may make it perform the transition by three or more steps including a highly efficient torque value, and the transition by the continuous change including a highly efficient torque value. Furthermore, in the electric motor 1 mounted on the vehicle 9, the driver's intention is estimated based on the operation of the accelerator, the brake, etc. by learning the driver's driving rod, and the transition of the instantaneous torque T (t) is performed. Or setting of unit time tA may be considered.

  The present invention can be implemented without being limited to differences in the type of power source of the motor 1, the type such as the synchronous type and the induction type, the control method and the internal structure, etc. it can. Various other modifications and applications of the present invention are possible.

1: Electric motor 11: Output shaft 2: DC power supply 3: Inverter device 4: Electric motor ECU
5: Vehicle ECU 6: Reducer 7: Torque transition absorber 9: Vehicle N: Number of revolutions Nmax: Maximum number of revolutions T: Torque, braking torque Tmax: Maximum torque Tx: Regenerative torque K: Road gradient η: Efficiency Emax: Maximum Efficiency line AL: Low load region GH: High-speed cruise center of gravity GL: City center of gravity center v: Vehicle speed D: Required operating point n1: Required speed Tn1: Required torque Dmax: Maximum efficiency point Tn1e-max: Maximum efficiency torque value tA : Unit time tB: Energizing time tC: Carrier cycle Vdc: DC voltage V: Rectangular wave voltage I: Current

Claims (8)

A control method for an electric motor that controls an electric input so that an actual output operation point and output torque coincide with the required operation point based on a variable request rotation number and a required torque that are required operation points. And
Through a predetermined unit time, the output rotational speed is made to coincide with the required rotational speed continuously, and a maximum efficiency torque value that is a torque value at which the highest efficiency is obtained under the conditions of the required rotational speed, and the electric input The instantaneous torque that the motor actually outputs is changed by combining the zero torque value at the time of erasing with the time ratio within the unit time ,
Controlling the electrical input so that the output torque determined by the time average value of the instantaneous torque through the unit time matches the required torque ;
While the required rotational speed and the required torque are constant, while maintaining the unit time substantially constant,
A method for controlling an electric motor in which at least one of the time ratio, the maximum efficiency torque value, and the zero torque value is slightly changed or oscillated for each unit time as time passes . The method for controlling an electric motor according to claim 1 , wherein the unit time is slightly changed or oscillated with time. A control method for an electric motor that controls an electric input so that an actual output operation point and output torque coincide with the required operation point based on a variable request rotation number and a required torque that are required operation points. And
Through a predetermined unit time, the output rotational speed is made to coincide with the required rotational speed continuously, and a maximum efficiency torque value that is a torque value at which the highest efficiency is obtained under the conditions of the required rotational speed, and the electric input The instantaneous torque that the motor actually outputs is changed by combining the zero torque value at the time of erasing with the time ratio within the unit time,
Controlling the electrical input so that the output torque determined by the time average value of the instantaneous torque through the unit time matches the required torque;
While the required rotational speed and the required torque are constant, while maintaining the unit time substantially constant,
An electric motor control method in which the unit time is slightly changed or oscillated with time . In any one of Claims 1-3 ,
The electric input control method is a voltage-type pulse width modulation control method for variably controlling the duty ratio of the rectangular wave voltage within a repeated carrier cycle.
The electric motor control method, wherein the unit time is at least twice the carrier cycle and is set according to the required rotational speed and the required torque. 5. The motor control method according to claim 1 , further comprising: a torque transition absorption device that absorbs the transition of the instantaneous torque and suppresses the instantaneous change on the output side of the motor. 6. In any one of Claims 1-5 , when the said request | requirement rotation speed and the said request | requirement torque satisfy | fill predetermined conditions, while making the said output rotation speed correspond to the said request | requirement rotation speed continuously through the said unit time, the said When the instantaneous torque is changed including a high-efficiency torque value and the predetermined condition is not satisfied, the output rotational speed is continuously matched with the required rotational speed through the unit time and the instantaneous torque is matched with the required torque. An electric motor control method for continuously matching torques. 7. The motor control method according to claim 6 , wherein the predetermined condition is a condition in which a time change rate of the required rotational speed and the required torque is equal to or less than a predetermined threshold value. The method for controlling an electric motor according to any one of claims 1 to 7 , wherein the electric motor is mounted on a hybrid vehicle or an electric vehicle and used as a travel drive source.

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