Motor controller and motor control method

Abstract

To provide a motor controller and a motor control method, which can highly precisely limit power of a drive circuit.SOLUTION: A motor controller for controlling a motor by supplying a driving signal generated based on a rotation command value by a drive circuit to the motor includes: a voltage detection part for detecting voltage of the driving signal as load voltage; a current detection part for detecting current of the driving signal as load current; and a power limit part for detecting load power of the drive circuit based on load voltage and load current and limiting power by lowering the rotation command value when load power exceeds a prescribed upper limit value.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a motor control device and a motor control method. [Background technology]

[0002] The following Patent Document 1 discloses a fan motor control method and a fan motor control device. This background technology involves detecting the load on the inverter main circuit when driving a fan motor (brushless DC motor) with an inverter main circuit, and reducing the command rotation speed output from the motor control unit to the inverter main circuit if the detected load is equal to or greater than a predetermined load, and increasing the command rotation speed if the detected load is smaller than the predetermined load. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2001-286179 A Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, the above-mentioned background art provides thermal protection for the inverter main circuit by reducing the command rotation speed when an overload is detected, but the load is detected based on the motor current supplied from the inverter main circuit (drive circuit) to a fan motor (control target).

[0005] That is, the background art cannot accurately detect the load when the voltage applied to the controlled object, i.e., the motor voltage, is variable. Therefore, the background art has a problem in that it cannot accurately limit the power of the drive circuit.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide a motor control device and a motor control method that are capable of limiting the power of a drive circuit with greater precision. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention employs, as a first solution relating to a motor control device, a motor control device that controls a motor by supplying to the motor a drive signal generated by a drive circuit based on a rotation command value, and is equipped with a voltage detection unit that detects the voltage of the drive signal as a load voltage, a current detection unit that detects the current of the drive signal as a load current, and a power limiting unit that detects the load power of the drive circuit based on the load voltage and load current, and implements power limiting by reducing the rotation command value when the load power exceeds a predetermined upper limit.

[0008] The present invention provides a second solution related to a motor control device, which is the above-mentioned first solution, in which the power limiting unit increases the rotation command value when the load power falls below a predetermined lower limit.

[0009] The present invention provides a third solution related to a motor control device, which is the first solution described above, in which the power limiting unit releases the power limit when the load power falls below a predetermined release value, a higher command rotation speed lower than the current command rotation speed is specified, and the load power falls below the release value.

[0010] The present invention provides a fourth solution related to a motor control device, which is any one of the first to third solutions described above, in which the voltage detection unit detects the power supply voltage supplied to the drive circuit as the load voltage.

[0011] In the present invention, as a solution relating to a motor control method, a motor control method is adopted in which a drive circuit controls a motor by supplying to the motor a drive signal generated based on a rotation command value, the method having a load power detection process that detects the load power of the drive circuit based on the load voltage and load current of the drive circuit, and a rotation command value correction process that implements power limitation by reducing the rotation command value when the load power exceeds a predetermined upper limit value. Effect of the Invention

[0012] According to the present invention, it is possible to provide a motor control device and a motor control method that are capable of limiting the power of a drive circuit with greater precision. [Brief description of the drawings]

[0013] [Figure 1] 1 is a block diagram showing a configuration of a motor control device A according to one embodiment of the present invention. [Diagram 2] 3 is a flowchart illustrating a motor control method according to an embodiment of the present invention. [Diagram 3] 4 is a timing chart showing a motor control method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, a motor control device A according to this embodiment includes a microcomputer 1, a motor control IC 2, a motor drive circuit 3, a power supply circuit 4, and a low-voltage power supply circuit 5 as functional components.

[0015] This motor control device A is a vehicle control device mounted on a vehicle and operates based on battery power supplied from a battery B also mounted on the vehicle. As shown in the figure, battery power, which is the output of battery B, is supplied to this motor control device A via a fuse F.

[0016] Moreover, this motor control device A is an in-vehicle motor control device that controls the motor M under the control of a host control device J (ECU) mounted on the vehicle. The host control device J comprehensively controls the motor control device A, which is a component of the vehicle, together with other components by outputting a host control command value to the motor control device A. The host control command value is, for example, a host command rotation speed R0 that indicates a rotation target value of the motor M.

[0017] As shown in the figure, the microcomputer 1 includes a control command generating unit 1a and a power limiting unit 1b as functional components, and includes a storage unit, a calculation unit, and an input / output unit as hardware components.

[0018] The microcomputer 1 executes a motor control program pre-stored in the memory unit in the calculation unit, thereby generating a command rotation speed Ra (rotation command value) corresponding to a higher-level command rotation speed R0 (higher-level control command value) received by the input / output unit from the higher-level control device J (ECU), and outputs the command rotation speed Ra to the motor control IC 2 via the input / output unit.

[0019] The control command generator 1a is a functional component that performs the main function of the microcomputer 1 described above, that is, the function of generating a command rotation speed Ra (rotation command value). That is, the control command generator 1a receives the upper command rotation speed R0 as a main input signal, generates a command rotation speed Ra corresponding to the upper command rotation speed R0, and outputs it to the motor control IC2.

[0020] Furthermore, when a power limit signal is input from the power limiting unit 1b, the control command generating unit 1a modifies the command rotation speed Ra according to the content of the power limiting signal (power limit content). The power limit content includes a) a reduction in the load power of the motor drive circuit 3 by lowering the command rotation speed Ra, b) an increase in the load power of the motor drive circuit 3 by raising the command rotation speed Ra, and c) a current value of the command rotation speed Ra is maintained to maintain the load power of the motor drive circuit 3.

[0021] The power limiting unit 1b is a functional component that performs a sub-function of the microcomputer 1 for the control command generating unit 1a, that is, a function of limiting power consumption in the motor drive circuit 3. In other words, the power limiting unit 1b reduces or increases the rotation command value of the control command generating unit 1a based on the load voltage and load current of the motor drive circuit 3 input from the motor drive circuit 3 via the motor control IC 2.

[0022] Although details will be described later, the power limiting unit 1b calculates the load power Wa of the motor drive circuit 3 as a drive load based on the load voltage and load current of the motor drive circuit 3. This power limiting unit 1b generates the above-mentioned power limiting signal by comparing the load power Wa (drive load) with power limiting thresholds such as an upper limit value WH, a release value WK, and a lower limit value Wa.

[0023] Moreover, the power limiting unit 1b outputs the power limiting signal to the control command generating unit 1a to correct the command rotation speed Ra. By correcting the command rotation speed Ra based on the power limiting signal, the load power of the motor driving circuit 3 functioning as a power conversion circuit changes as a result. In other words, such a power limiting unit 1b is the main body of the power limiting control of the motor driving circuit 3 that the microcomputer 1 executes as a secondary function.

[0024] As shown in the figure, the motor control IC 2 includes a voltage detection unit 2a, a current detection unit 2b, and a control signal generation unit 2c as functional components. The motor control IC 2 is an integrated circuit (IC) that includes multiple input terminals and multiple output terminals as hardware components.

[0025] In such a motor control IC 2, the voltage detection unit 2a has an input terminal connected to the power supply terminal of the motor drive circuit 3, and detects the power supply voltage of the motor drive circuit 3 as a load voltage when generating a drive signal. The voltage detection unit 2a outputs such a load voltage (power supply voltage) to the power limiting unit 1b of the microcomputer 1.

[0026] The current detection unit 2b has a pair of input terminals that are connected to both ends of a shunt resistor provided in the motor drive circuit 3. That is, one input terminal of the current detection unit 2b is connected to one end of the shunt resistor, and the other input terminal is connected to the other end of the shunt resistor.

[0027] The current detection unit 2b detects the current passed through the motor drive circuit 3 via the motor M, that is, the drive current flowing through the motor drive circuit 3 and the motor M based on the drive signal that the motor drive circuit 3 generates for the motor M, as the load current of the motor drive circuit 3. The current detection unit 2b outputs the load current of the motor drive circuit 3 to the power limiting unit 1b of the microcomputer 1.

[0028] The control signal generating unit 2c is a functional component that performs the main function of the motor control IC 2, that is, the function of generating a drive control signal. This control signal generating unit 2c generates a drive control signal based on the rotation command value input from the control command generating unit 1a of the microcomputer 1 and the waveform of the drive signal input from the motor drive circuit 3. The control signal generating unit 2c outputs such a drive control signal to the motor drive circuit 3.

[0029] The motor drive circuit 3 is a drive signal generation circuit that generates a drive signal to be supplied to the motor M based on a drive control signal input from the motor control IC 2. The motor drive circuit 3 is a type of power conversion circuit that converts the power supply power (DC power) supplied from the power supply circuit 4 into a drive signal (AC power) based on the drive control signal.

[0030] Such a motor drive circuit 3 is typically a three-phase inverter circuit. That is, the motor drive circuit 3 is made up of a U-phase switching leg, a V-phase switching leg, and a W-phase switching leg connected in parallel to the power supply circuit 4. Each of the U-phase switching leg, the V-phase switching leg, and the W-phase switching leg includes an upper arm switching transistor and a lower arm switching transistor.

[0031] That is, the U-phase switching leg, the V-phase switching leg, and the W-phase switching leg are each a switching circuit in which an upper arm switching transistor and a lower arm switching transistor are connected in series. The motor drive circuit 3 also includes shunt resistors connected in series to the U-phase switching leg, the V-phase switching leg, and the W-phase switching leg.

[0032] Furthermore, when the motor drive circuit 3 is configured as a three-phase inverter circuit, the drive control signal is typically a PWM (Pulse Width Modulation) signal. That is, the control signal generator 2c of the motor control IC 2 generates pulse signals that turn on (conducting) / off (non-conducting) three upper arm switching transistors and three lower arm switching transistors in the U-phase switching leg, the V-phase switching leg, and the W-phase switching leg.

[0033] The input terminal of the power supply circuit 4 is connected to the other terminal of the fuse F, and transforms the battery power supplied from the battery B via the fuse F. The output terminal of this power supply circuit 4 is connected to the power supply terminal of the motor control IC 2 and the input terminal of the motor drive circuit 3, and supplies the motor control IC 2 and the motor drive circuit 3 with power supply power obtained by transforming the battery power.

[0034] The input terminal of the low-voltage power supply circuit 5 is connected to the output terminal of the power supply circuit 4, and reduces the power supply power input from the power supply circuit 4 to a voltage that meets the specifications of the microcomputer 1. The output terminal of this low-voltage power supply circuit 5 is connected to the power supply terminal of the microcomputer 1, and supplies the reduced power supply to the microcomputer 1.

[0035] Next, the operation of the main parts of the motor control device A according to this embodiment, that is, the motor control method according to this embodiment, will be described in detail with reference to FIG. 2 and FIG.

[0036] Prior to describing the operation of the main parts of the motor control device A, the main operation of the motor control device A will be described. In this motor control device A, upper command rotation speed R0 (upper control command value) corresponding to the state of the vehicle is input sequentially from the upper control device J. In this motor control device A, the control command generating unit 1a of the microcomputer 1 generates a command rotation speed Ra (rotation command value) corresponding to the upper command rotation speed R0 and outputs it to the control signal generating unit 2c of the motor control IC2.

[0037] The control signal generating unit 2c of the motor control IC 2 generates a drive control signal based on the command rotation speed Ra input from the control command generating unit 1a and outputs the signal to the motor drive circuit 3. The motor drive circuit 3 generates a drive signal based on the drive control signal input from the control signal generating unit 2c and supplies the drive signal to the motor M. As a result, the motor M rotates at a rotation speed according to the upper command rotation speed R0 input from the upper control device J to the motor control device A.

[0038] In the main operation of such a motor control device A, if the motor drive circuit 3 falls into an overload state due to generating a drive signal based on the upper command rotation speed R0, it may abnormally heat up and be damaged, or in some cases, may even break down and become unable to generate a drive signal.

[0039] The main operation of the motor control device A is based on the power limiting section 1b of the microcontroller 1 and the voltage detection section 2a and current detection section 2b of the motor control IC 2. The load power (driving load) of the motor drive circuit 3 is detected based on the load voltage detected by the voltage detection section 2a and the load current detected by the current detection section 2b, and the command rotation speed Ra is corrected so as to at least decrease based on the result of comparing this load power (driving load) with a predetermined control threshold value.

[0040] 2, in such a main operation, the power limiting unit 1b of the microcomputer 1 first detects the load power Wa (drive load) based on the load voltage input from the voltage detecting unit 2a and the load current input from the current detecting unit 2b (step S1). That is, the power limiting unit 1b calculates the load power WL of the motor driving circuit 3 by multiplying the load voltage and the load current. This step S1 corresponds to the load power detection process in the present invention.

[0041] Then, the power limiting unit 1b judges whether the motor drive circuit 3 is already in a power limiting state (step S2). The power limiting unit 1b has a memory area for storing, for example, a plurality of control variables (flags) indicating past power limiting states, and judges whether the current state is under power limiting by referring to a control variable (first flag) indicating whether or not power limiting is being implemented among the plurality of control variables stored in this memory area.

[0042] If the result of the determination in step S2 is "Yes", that is, if the power is being limited, the power limiting unit 1b determines whether the upper command rotation speed R0 is different from the command rotation speed Ra (step S3). If the result of the determination in step S2 is "Yes", the power limiting unit 1b determines whether the upper command rotation speed R0 is greater than the command rotation speed Rb during the power limit (step S4).

[0043] If the result of the determination in step S4 is "Yes", the power limiting unit 1b determines whether the load power Wa is greater than the upper limit value WH of the power limit thresholds described above (step S5). If the result of the determination in step S5 is "Yes", the power limiting unit 1b outputs a power limit signal indicating a rotation reduction process to the control command generating unit 1a (step S6). This step S6 corresponds to the rotation command value correction process in the present invention.

[0044] The rotation reduction process is a process for correcting the command rotation speed Rb during power limitation to a rotation speed lower than the upper command rotation speed R0, against the upper command rotation speed R0. That is, when the power limiting unit 1b has not yet performed power limitation, the control command generating unit 1a generates a command rotation speed Ra equal to the command rotation speed R0, but when a power limiting signal indicating the rotation reduction process is input from the power limiting unit 1b, the control command generating unit 1a corrects the command rotation speed Rb during power limitation to a corrected command rotation speed Rc indicating a rotation speed lower than the upper command rotation speed R0.

[0045] As a result, the control signal generating unit 2c of the motor control IC 2 generates a corrected drive control signal based on the corrected command rotation speed Rc and outputs it to the motor drive circuit 3. Then, the motor drive circuit 3 generates a corrected drive signal based on the corrected drive control signal and supplies it to the motor M. Since this corrected drive signal reduces the rotation speed of the motor M, the load power of the motor drive circuit 3 decreases and the rotation speed of the motor M also decreases.

[0046] Then, when this rotation speed reduction process is completed, the power limiting unit 1b stores in the memory area the implementation status of the power limit on the motor drive circuit 3 (step S7). That is, the power limiting unit 1b stores in the memory area that the power limit on the motor drive circuit 3 is being implemented and that the motor drive circuit 3 is being controlled based on the corrected command rotation speed Rc.

[0047] If the result of the determination in step S5 is "No", the power limiting unit 1b determines whether the load power Wa is smaller than the lower limit value WL of the power limit threshold (step S8). If the result of the determination in step S8 is "Yes", the power limiting unit 1b outputs a power limit signal indicating a rotation increase process to the control command generating unit 1a (step S9). This step S9 corresponds to the rotation command value correction process in the present invention.

[0048] The rotation increase process is a process for correcting the command rotation speed Rb during power restriction to a rotation speed higher than the current value. That is, when the load power Wa is smaller than the lower limit value WL, the control command generating unit 1a corrects the command rotation speed Rb during power restriction to a corrected command rotation speed Rd indicating a rotation speed higher than the current value when a power limiting signal indicating the rotation increase process is input from the power limiting unit 1b.

[0049] As a result, the control signal generating unit 2c of the motor control IC 2 generates a corrected drive control signal based on the corrected command rotation speed Rd and outputs it to the motor drive circuit 3. Then, the motor drive circuit 3 generates a corrected drive signal based on the corrected drive control signal and supplies it to the motor M. Since this corrected drive signal increases the rotation speed of the motor M, the load power of the motor drive circuit 3 increases and the rotation speed of the motor M also increases.

[0050] Then, when this rotation increase process is completed, the power limiting unit 1b stores in the memory area the implementation status of the power limitation on the motor drive circuit 3 (step S10). That is, the power limiting unit 1b stores in the memory area that the power limitation on the motor drive circuit 3 is being implemented and that the motor drive circuit 3 is being controlled based on the corrected command rotation speed Rd.

[0051] Furthermore, if the result of the determination in step S8 is "No", the power limiting unit 1b outputs a power limiting signal indicating a rotation maintaining process to the control command generating unit 1a (step S11). This rotation maintaining process is a process for maintaining the command rotation speed Rb during power limiting at its current value. That is, when the power limiting signal indicating the rotation maintaining process is input from the power limiting unit 1b, the control command generating unit 1a maintains the command rotation speed Rb during power limiting at its current value.

[0052] As a result, the control signal generating unit 2c generates a drive control signal based on the command rotation speed Rb during the power limit and outputs it to the motor drive circuit 3. Then, the motor drive circuit 3 generates a drive signal based on the drive control signal and supplies it to the motor M. As a result, the load power of the motor drive circuit 3 is maintained at the current value, and the rotation speed of the motor M is maintained at the current value.

[0053] Then, when this rotation maintaining process is completed, the power limiting unit 1b stores in the memory area the implementation status of the power limitation on the motor drive circuit 3 (step S12). That is, the power limiting unit 1b stores in the memory area that the power limitation on the motor drive circuit 3 is being implemented and that the motor drive circuit 3 is being controlled based on the command rotation speed Rb.

[0054] If the result of the determination in step S4 is "No," that is, if the upper command rotation speed R0 is equal to or lower than the power-limited command rotation speed Rb, the power limiting unit 1b executes a process of substituting the upper command rotation speed R0 for the command rotation speed Rb (step S13). As a result, the control signal generating unit 2c generates a drive control signal based on the power-limited command rotation speed Rb (=upper command rotation speed R0) and outputs the drive control signal to the motor drive circuit 3.

[0055] Then, the motor drive circuit 3 generates a drive signal based on the drive control signal and supplies the drive signal to the motor M. As a result, the load power of the motor drive circuit 3 is set based on the upper command rotation speed R0, and the rotation speed of the motor M is set based on the upper command rotation speed R0.

[0056] Then, the power limiting unit 1b stores in the memory area the implementation status of the power limitation on the motor drive circuit 3 (step S14). That is, the power limiting unit 1b stores in the memory area that the power limitation on the motor drive circuit 3 is being implemented and that the motor drive circuit 3 is being controlled based on the upper command rotation speed R0.

[0057] Furthermore, if the result of the determination in step S3 is "No," that is, if the upper command rotation speed R0 is equal to the command rotation speed Rb during power limiting, the power limiting unit 1b determines whether the load power Wa is greater than the release value WK of the power limit thresholds described above (step S15). If the result of the determination in step S15 is "Yes," the power limiting unit 1b outputs a power limit signal indicating a rotation reduction process to the control command generating unit 1a (step S16). This step S16 corresponds to the rotation command value correction process in the present invention.

[0058] This rotation speed reduction process is the same as step S6 described above. As a result of this rotation speed reduction process, the command rotation speed Rb during power limitation is corrected to the corrected command rotation speed Rc, so that the control signal generating unit 2c of the motor control IC 2 generates a corrected drive control signal based on the corrected command rotation speed Rc and outputs it to the motor drive circuit 3.

[0059] Then, the motor drive circuit 3 generates a corrected drive signal based on the corrected drive control signal and supplies it to the motor M. This corrected drive signal reduces the rotation speed of the motor M, so that the load power of the motor drive circuit 3 decreases and the rotation speed of the motor M decreases.

[0060] When the rotation speed reduction process in step S16 is completed, the power limiting unit 1b saves the implementation status of the power limit on the motor drive circuit 3 in the memory area (step S17). That is, the power limiting unit 1b stores in the memory area that the power limit on the motor drive circuit 3 is being implemented and that the motor drive circuit 3 is being controlled based on the corrected command rotation speed Rc.

[0061] Furthermore, if the result of the determination in step S15 is "No", that is, if the load power Wa is equal to or less than the release value WK, the power limiting unit 1b outputs a power limiting signal indicating the end of power limiting on the motor drive circuit 3 to the control command generating unit 1a (step S18). As a result, the motor drive circuit 3 generates a drive signal based on the upper command rotation speed R0 and supplies it to the motor M, and the motor M rotates at the rotation speed based on the upper command rotation speed R0.

[0062] Then, when the process of step S18 is completed, the power limiting unit 1b stores in the memory area the implementation status of the power limitation on the motor drive circuit 3 (step S19). That is, the power limiting unit 1b stores in the memory area that the implementation of the power limitation on the motor drive circuit 3 has been completed and that the motor drive circuit 3 is being controlled based on the upper command rotation speed R0.

[0063] Furthermore, if the result of the determination in step S2 is "No", that is, if the motor drive circuit 3 is not being power-limited, the power limiting unit 1b determines whether the load power Wa is greater than the upper limit value WH (step S20). If the result of the determination in step S20 is "Yes", the power limiting unit 1b sets the command rotation speed Rb at the start of power limiting to a predetermined value (step S21).

[0064] Then, the power limiting unit 1b outputs a power limiting signal indicating the command rotation speed Rb to the control command generating unit 1a, thereby starting power limiting of the motor drive circuit 3 (step S22). Then, the control command generating unit 1a outputs the command rotation speed Rb to the control signal generating unit 2c of the motor control IC 2. The control signal generating unit 2c generates a drive control signal based on the command rotation speed Rb and outputs it to the motor drive circuit 3.

[0065] As a result, the motor drive circuit 3 generates a drive signal based on the drive control signal corresponding to the command rotation speed Rb and supplies the drive signal to the motor M. That is, the motor drive circuit 3 is in a state where the load power is limited by the command rotation speed Rb. The motor M then rotates at a rotation speed based on the drive signal corresponding to the command rotation speed Rb.

[0066] Then, when the power limiting start process of step S22 is completed, the power limiting unit 1b saves the implementation status of the power limit on the motor drive circuit 3 in the memory area (step S23). That is, the power limiting unit 1b stores in the memory area that the power limit on the motor drive circuit 3 is being implemented and that the motor drive circuit 3 is being controlled based on the command rotation speed Rb. If the determination result of step S20 is "No", the power limiting unit 1b ends the entire process as shown in the figure.

[0067] Figure 3 is a timing chart based on such a motor control method. In this timing chart, the top waveform shows the time series changes in the load power Wa. The second waveform from the top shows the time series changes in the upper command rotation speed R0, and the third waveform from the top shows the time series changes in the command rotation speed R. Furthermore, the bottom waveform shows whether power limiting of the motor drive circuit 3 is implemented (ON) or not (OFF).

[0068] As shown in the timing chart of Fig. 3(a), when the load power Wa exceeds the upper limit value WH, the power limit is implemented (ON) and the command rotation speed R is reduced. This reduction in the command rotation speed R reduces the load power Wa and makes it fall below the upper limit value WH.

[0069] The power limit is released when a higher-level command rotation speed R0 lower than the current command rotation speed R is specified by the higher-level control device J and the load power Wa is below the release value WK. That is, when the above two conditions are met, the power limit is switched from being implemented (ON) to not being implemented (OFF). The power limit is released after the command rotation speed R is updated to the higher-level command rotation speed R0.

[0070] Here, even if the load power Wa falls below the upper limit value WH due to a decrease in the command rotation speed R, the power limit is not immediately switched from implementation (ON) to non-implementation (OFF). In other words, once the power limit starts to be implemented (ON), the power limit continues to be implemented (ON) even if the load power Wa falls below the upper limit value WH.

[0071] The implementation of power limiting (ON) is switched to not being implemented (OFF) when the load power Wa falls below the release value WK, a higher-level command rotation speed R0 lower than the current command rotation speed R is specified by the higher-level control device J, and the load power Wa is also below the release value WK.

[0072] Also, as shown in the timing chart of FIG. 3(b), when the load power Wa falls below the lower limit WL while the power limit is in effect (ON), the command rotation speed Ra (rotation command value) is increased until the load power Wa exceeds the lower limit WL.

[0073] The motor control device A of this embodiment controls the motor M by supplying to the motor M a drive signal generated by the motor drive circuit 3 (drive circuit) based on a command rotation speed Ra (rotation command value), and is equipped with a voltage detection unit 2a that detects the voltage of the drive signal as a load voltage, a current detection unit 2b that detects the current of the drive signal as a load current, and a power limiting unit 1b that detects the load power Wa of the motor drive circuit 3 (drive circuit) based on the load voltage and load current, and implements power limiting by reducing the command rotation speed Ra (rotation command value) when this load power Wa exceeds a predetermined upper limit value WH.

[0074] The motor control method of this embodiment controls a motor M by supplying a drive signal generated by a motor drive circuit 3 (drive circuit) based on a command rotation speed Ra (rotation command value) to the motor M, and includes a load power detection process that detects the load power Wa of the motor drive circuit 3 (drive circuit) based on the load voltage and load current of the motor drive circuit 3 (drive circuit), and a rotation command value correction process that reduces the command rotation speed Ra (rotation command value) when the load power Wa exceeds a predetermined upper limit value WH.

[0075] According to this embodiment, the motor control device A and the motor control method are provided which are equipped with a voltage detection unit 2a, a current detection unit 2b and a power limiting unit 1b, and manipulate the command rotation speed Ra (rotation command value) based on the load power Wa, thereby making it possible to provide a motor control device A and a motor control method which are capable of more accurately limiting the power of the motor drive circuit 3 (drive circuit).

[0076] Furthermore, in the motor control device A of this embodiment, the power limiting unit 1b increases the command rotation speed Ra (rotation command value) when the load power Wa falls below a predetermined release value WK and also falls below the lower limit value WL, so that it is possible to precisely implement power limitation of the motor drive circuit 3 (drive circuit) while rotating the motor M in a state close to no power limitation.

[0077] The present invention is not limited to the above-described embodiment, and the following modifications are possible. (1) In the above embodiment, the present invention is described as being applied to the control of a motor M mounted on a vehicle, but the present invention is not limited to this. The present invention can be applied to the control of motors for various purposes.

[0078] (2) In the above embodiment, the command rotation speed Ra (rotation command value) is increased when the load power Wa falls below the predetermined release value WK and also falls below the lower limit value WL, but the present invention is not limited to this. For example, the command rotation speed Ra (rotation command value) may be increased when the load power Wa falls below the lower limit value WL without setting the release value WK.

[0079] (3) Furthermore, the rotation increase process (step S9) for increasing the command rotation speed Ra (rotation command value) when the load power Wa falls below the lower limit WL is not essential and may be omitted as necessary.

[0080] (4) In the above embodiment, when the motor drive circuit 3 (drive circuit) is configured as a three-phase inverter circuit, the power supply voltage supplied to the motor drive circuit 3 (drive circuit) is detected as the load voltage, but the present invention is not limited to this. In other words, the load voltage in the present invention is not limited to the power supply voltage. [Explanation of symbols]

[0081] A...motor control device, B...battery, F...fuse, M...motor, J...host control device (ECU), 1...microcomputer, 1a...control command generation unit, 1b...power limiting unit, 2...motor control IC, 2a...voltage detection unit, 2b...current detection unit, 2c...control signal generation unit, 3...motor drive circuit, 4...power supply circuit, 5...low-voltage power supply circuit,

Claims

1. A motor control device in which a drive circuit controls a motor by supplying a drive signal generated based on a rotation command value to the motor, a voltage detection unit that detects a voltage of the drive signal as a load voltage; a current detection unit that detects a current of the drive signal as a load current; a power limiting unit that detects a load power of the drive circuit based on the load voltage and the load current, and implements power limiting by reducing the rotation command value when the load power exceeds a predetermined upper limit value; A motor control device comprising:

2. 2. The motor control device according to claim 1, wherein the power limiting unit increases the rotation command value when the load power falls below a predetermined lower limit value.

3. 2. The motor control device according to claim 1, wherein the power limiting unit releases the power limit when the load power falls below a predetermined release value, a higher command rotation speed lower than a current command rotation speed is specified, and the load power falls below the release value.

4. 3. The motor control device according to claim 1, wherein the voltage detection unit detects a power supply voltage supplied to the drive circuit as the load voltage.

5. 1. A motor control method in which a drive circuit controls a motor by supplying a drive signal generated based on a rotation command value to the motor, the method comprising: a load power detection step of detecting a load power of the drive circuit based on a load voltage and a load current of the drive circuit; a rotation command value correction process for implementing power limitation by reducing the rotation command value when the load power exceeds a predetermined upper limit value; 13. A motor control method comprising:

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