Electric-motor control device

Abstract

Disclosed is an electric-motor control device that makes it possible to suppress overcurrent or overvoltage if there is a sudden change in the rotational speed of the electric motor. This electric-motor control device (200) uses a power conversion device (20) to drive and control an electric motor (10), and is provided with: a control mode switching unit (208) for switching between a plurality of control modes (204, 205) for driving and controlling the electric motor if a predetermined state quantity (Φd) exceeds a predetermined threshold value; and a filter unit for filtering electrical angular velocity of the electric motor. The filtering by the filter unit is stopped and the predetermined threshold value is raised if the rate of change in the electrical angular velocity reaches or exceeds a predetermined value.

Description

Electric motor control device

[0001] The present invention relates to a motor control device that controls the drive of an electric motor using a power conversion device.

[0002] The square wave (single pulse) drive of an electric motor is used in the high speed range of the electric motor because it can increase the modulation rate. A rotating electric machine control system such as that described in Patent Document 1 is known as a conventional control device having a control mode for square wave drive of an electric motor.

[0003] The control system described in Patent Document 1 has a sinusoidal current control mode and an overmodulation current control mode that output a PWM pattern, and a square wave voltage phase control mode that outputs a one-pulse switching waveform. These three control modes are switched according to the modulation rate or the voltage command amplitude corresponding to the modulation rate.

[0004] JP 2010-81663 A

[0005] In the above-mentioned conventional technology, when the rotation speed of the motor suddenly changes, the control mode cannot be switched to keep up, and the voltage applied to the motor and the current flowing through the motor become larger than necessary.

[0006] Therefore, the present invention provides a motor control device that has a plurality of control modes and is capable of suppressing overcurrent or overvoltage when the rotation speed of the motor changes suddenly.

[0007] In order to solve the above problems, the electric motor control device according to the present invention controls the drive of an electric motor using a power conversion device, and includes a control mode switching unit that switches between multiple control modes for controlling the drive of the electric motor when a predetermined state quantity exceeds a predetermined threshold, and a filter unit that filters the electric angular velocity of the electric motor, and when the rate of change of the electric angular velocity becomes equal to or greater than a predetermined value, the filtering by the filter unit is stopped and the predetermined threshold is raised.

[0008] According to the present invention, when the rotation speed of the electric motor changes suddenly, an overcurrent or an overvoltage can be suppressed.

[0009] Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments.

[0010] Fig. 1 is a circuit diagram and functional block diagram showing the configuration of an electric motor drive system according to one embodiment. Fig. 2 is a flowchart showing the operation of a speed calculation unit 211 (Fig. 1) to detect a sudden change in rotation speed. Fig. 3 is a flowchart showing the operation of a speed calculation unit 211 (Fig. 1) to determine whether a sudden change in rotation speed has been released. Fig. 4 is a functional block diagram showing the configuration of the speed calculation unit 211 (Fig. 1). Fig. 5 is a functional block diagram showing the configuration of a gain setting unit in a current control unit 202 (Fig. 1). Fig. 6 is a functional block diagram showing the configuration of a portion of a control mode switching unit 208 (Fig. 1).

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same reference numerals indicate the same components or components having similar functions.

[0012] FIG. 1 is a circuit diagram and a functional block diagram showing the configuration of an electric motor drive system according to an embodiment of the present invention.

[0013] 1, in this embodiment, an inverter circuit 20 and a DC power supply 40 are connected to each other via a smoothing capacitor 30. The inverter circuit 20 constitutes a main circuit of a so-called voltage-type inverter. The DC power supply 40 may be, for example, a battery.

[0014] In this embodiment, DC power from a DC power supply 40 is converted into three-phase AC power by an inverter circuit 20, and a permanent magnet synchronous motor (hereinafter referred to as a "PM motor") 10 is rotationally driven by the three-phase AC power output by the inverter circuit 20.

[0015] The inverter circuit 20 includes six semiconductor switching elements (insulated gate bipolar transistors (IGBTs) in FIG. 1 ), which are connected in pairs in series to form upper and lower arms for three phases (U phase, V phase, and W phase). Each series connection point of the upper and lower arms for the three phases is electrically connected to a three-phase AC terminal of the PM motor 10. Both ends of the upper and lower arms are electrically connected to a DC power supply 40. A diode is electrically connected in anti-parallel to each semiconductor switching element (between the collector and emitter of the IGBT in FIG. 1 ). This diode operates as a so-called freewheeling diode.

[0016] In the inverter circuit 20, the semiconductor switching elements perform a switching operation to convert DC power input from the DC power supply 40 into three-phase AC power, which is then output from the series connection point between the upper and lower arms to the PM motor 10. The smoothing capacitor 30 suppresses fluctuations in the input voltage caused by the switching operation, thereby stabilizing the operation of the inverter circuit 20.

[0017] The control device 200 outputs a control signal (gate signal) to the control terminals of the semiconductor switching elements in the inverter circuit 20 (gate terminals of the IGBTs in FIG. 1 ), and controls the semiconductor switching elements to control the current supplied to the PM motor 10, thereby controlling the torque and speed of the PM motor 10. In this embodiment, the control device 200 controls the three-phase AC current value i ｕ , i ｖ , i ｗ Based on ｕ , i ｖ , i ｗ is the desired torque (T ＊ Each semiconductor switching element is controlled so as to approach a current command value for obtaining the output voltage Vout.

[0018] 1, for simplicity, the current sensors that detect three-phase AC current are represented by a single current sensor 70. Alternatively, two phases of the three-phase AC current values ​​may be detected and the remaining phase may be calculated.

[0019] The control device 200 includes a current command value calculation unit 201, a current control unit 202, a voltage control unit 203, a PWM gate signal generation unit 207, a control mode switching unit 208, a current detection unit 209, a rotational position detection unit 210, and a speed calculation unit 211.

[0020] The control device 200 includes a computer system such as a microcomputer, and the computer system executes a predetermined program to operate each unit.

[0021] The rotation position detection unit 210 receives the rotation detection signal S from the rotation detector 90. ｒ The rotor angle θ is calculated based on the above equation, where θ represents the phase of the d-axis in the rotation coordinate system.

[0022] The current detection unit 209 uses θ from the rotation position detection unit 210 to calculate i ｕ , i ｖ , i ｗ is the d-axis current detection value I ｄ and the q-axis current detection value I ｑ Convert to.

[0023] The speed calculation unit 211 calculates the electrical angular velocity ω and the motor rotation speed N based on θ from the rotation position detection unit 210. The speed calculation unit 211 also includes a sudden change determination unit 212 that determines whether or not there is a sudden change in the rotation speed of the PM motor 10 based on θ. When the speed calculation unit 211 determines that there is a sudden change using the sudden change determination unit 212, it sets a sudden change determination flag FL1, which indicates the determination result, to ON (1), and when it determines that there is no sudden change, it sets the sudden change determination flag FL1 to OFF (0).

[0024] The current command value calculation unit 201 receives a torque command T ＊ and DC power supply voltage V ＤＣ and N from the speed calculation unit 211, the desired torque (T ＊ ) to obtain the d-axis current command value I ｄ ＊ and the q-axis current command value I ｑ ＊ Calculate V ＤＣis detected by a voltage detector 80 across the smoothing capacitor 30. In this embodiment, I is calculated based on the so-called maximum torque per ampere (MTPA) control. ｄ ＊ and I ｑ ＊ is calculated.

[0025] The current control unit 202 receives the I from the current detection unit 209. ｄ and I ｑ are the I from the current command value calculation unit 201. ｄ ＊ and I ｑ ＊ The d-axis voltage command value V ｄ ＊ and q-axis voltage command V ｑ ＊ Generate.

[0026] In this embodiment, the current control unit 202 calculates V using a voltage equation (inverse model) that expresses the dq-axis voltages applied to the PM motor 10 in terms of the dq-axis interlinkage magnetic flux of the PM motor 10. ｄ ＊ and V ｑ ＊ The dq-axis interlinkage flux in this voltage equation is I ｄ and I ｄ The detected d-linkage magnetic flux value Φ is calculated from ｄ Ga I ｄ ＊ The first d-axis interlinkage magnetic flux command value Φ calculated from ｄ ＊ The second d-axis interlinkage flux command value Φ generated by the PI controller is set to coincide with ｄ ＊＊ And, I ｄ and I ｄ The q interlinkage magnetic flux detection value Φ calculated from ｑ Ga I ｑ ＊ The first q-axis interlinkage magnetic flux command value Φ ｑ ＊ The second q-axis interlinkage flux command value Φ generated by the PI controller is set to coincide with ｑ ＊＊ Φ ｄ , Φ ｑ , Φｄ ＊ , Φ ｑ ＊ is calculated using a magnetic flux map, which is table data showing the correspondence between the d-axis current and the d-axis interlinkage magnetic flux in the PM motor 10. The angular frequency included in the voltage equation is ω from the speed calculation unit 211.

[0027] In this embodiment, the current control unit 202 is V ｄ ＊ , V ｑ ＊ , V ＤＣ Based on this, the modulation factor M is calculated (M=((V ｄ ＊ ) ２ + (V ｑ ＊ ) ２ ) １／２ / V ＤＣ ).

[0028] The voltage control unit 203 has an SVPWM (space vector PWM) control unit 204, a 3-pulse control unit 205, and a 1-pulse control unit 206. That is, the control device 200 has, as control modes for the PM motor 10, an SVPWM control unit mode, a 3-pulse control mode, and a 1-pulse control mode.

[0029] The voltage control unit 203 selects one of these three control units, and uses the selected control unit to adjust the duty ratio d of the three-phase voltage applied to the PM motor 10. ｕｖｗ (three-phase voltage command value).

[0030] The SVPWM control unit 204, the 3-pulse control unit 205, and the 1-pulse control unit 206 respectively control the PM motor 10 to perform sine wave drive, 3-pulse drive, and 1-pulse drive. ｕｖｗ is calculated. The amplitude of the voltage applied to the PM motor 10 increases in the order of sine wave drive, three-pulse drive, and one-pulse drive. Therefore, the rotation speed of the PM motor 10 increases in the order of sine wave drive, three-pulse drive, and one-pulse drive.

[0031] The SVPWM control unit 204 and the 3-pulse control unit 205 receive the V ｄ ＊and V ｑ ＊ Based on this, the duty ratio d of the three-phase voltage applied to the PM motor 10 is ｕｖｗ Calculate.

[0032] The one-pulse control unit 206 detects the I output from the current detection unit 209. ｄ , I ｑ are generated by the current command value calculation unit 201. ｄ ＊ , I ｑ ＊ , i.e., the PM motor 10 is set to the desired torque (T ＊ ) by voltage phase control. ｕｖｗ Calculate.

[0033] The PWM gate signal generator 207 receives the d ｕｖｗ In response to this, a control signal S is supplied to the control terminal of each semiconductor switching element in the inverter circuit 20 (in FIG. 1, the gate terminal of the IGBT). Ｇ (gate signal).

[0034] The control mode switching unit 208 receives M and Φ from the voltage control unit 203. ｄ , Φ ｄ ＊ , a switching control signal S for switching the control unit selected by the voltage control unit 203 from the SVPWM control unit 204, the 3-pulse control unit 205, and the 1-pulse control unit 206. ｃ Output.

[0035] In this embodiment, the control device 200 includes the following means for suppressing overcurrent or overvoltage when the rotation speed of the PM motor 10 changes suddenly.

[0036] As described above, the speed calculation unit 211 includes the sudden change determination unit 212 that determines whether or not there is a sudden change in the rotation speed of the PM motor 10 .

[0037] When the speed calculation unit 211 detects a sudden change in the rotation speed, it turns off the filter unit that removes frequency components and extracts the electrical angular velocity ω having the fundamental wave component. This reduces the deviation between ω and N calculated by the speed calculation unit 211 and the actual electrical angular velocity and rotation speed when the rotation speed suddenly changes.

[0038] When the rotation speed changes suddenly, the current control unit 202 increases the value of the control response gain to a value greater than a preset value (for example, 1.5 times). In this embodiment, the control response gain is a magnetic flux control response gain, i.e., Φ ｄ Φ ｄ ＊ and the proportional and integral gains in the PI controller to match Φ ｑ Φ ｑ ＊ This improves the response of the control, allowing the SVPWM control unit 204 and the 3-pulse control unit 205 to operate in response to sudden changes in the rotation speed.

[0039] The control mode switching unit 208 is ｄ Based on this, a switching control signal S for switching the control unit selected by the voltage control unit 203 between the SVPWM control unit 204 or the 3-pulse control unit 205 and the 1-pulse control unit 206 is output. ｃ Output.

[0040] In the above-mentioned MTPA control, I ｄ ＊ is set to a negative value. Therefore, the range of rotational speeds (rotational speeds) at which the PM motor 10 can operate with a constant torque is widened by the flux-weakening effect of the d-axis magnetic flux generated by the d-axis current. When the flux-weakening effect becomes large and the rotational speed exceeds the limit speed, the PM motor 10 can operate with a desired torque (T ＊ ) will no longer be output.

[0041] Therefore, when the control mode switching unit 208 determines that the magnitude of Φd is equal to or greater than a predetermined threshold value, it determines that the rotation speed of the PM motor 10 is at the limit speed, and outputs a switching control signal S ｃ Output.

[0042] When the rotation speed changes suddenly, the control mode switching unit 208 adds a constant value to a predetermined threshold value. This makes it easier to switch from the one-pulse control unit 206 to the SVPWM control unit 204 or the three-pulse control unit 205, and also makes it easier for the control unit selected by the voltage control unit 203 to remain at the SVPWM control unit 204 or the three-pulse control unit 205. As a result, when the rotation speed changes suddenly, the voltage control unit 203 selects the SVPWM control unit 204 or the three-pulse control unit 205, which have better control responsiveness than the one-pulse control unit. This makes it possible to suppress overvoltage and overcurrent in the electric motor when the rotation speed changes suddenly.

[0043] The control mode switching unit 208 outputs a switching control signal S for switching the control unit selected by the voltage control unit 203 between the SVPWM control unit 204 and the 3-pulse control unit 205 based on the modulation rate. ｃ Output.

[0044] When the modulation factor M increases, the control mode switching unit 208 outputs a switching control signal S ｃ Furthermore, when M is low, the control mode switching unit 208 keeps the control unit selected by the voltage control unit 203 at the SVPWM control unit 204.

[0045] When the rotation speed changes suddenly, control mode switching unit 208 maintains the control unit selected by voltage control unit 203 in SVPWM control unit 204 up to a modulation factor higher than the low modulation factor at which the control unit selected by voltage control unit 203 is normally maintained in SVPWM control unit 204. As a result, when the rotation speed changes suddenly, even if M fluctuates, the control unit selected by voltage control unit 203 is more likely to be maintained as SVPWM control unit 204, which has higher control responsiveness than three-pulse control unit 205. As a result, when the rotation speed changes suddenly, overvoltage and overcurrent in the motor can be suppressed.

[0046] 2 is a flowchart showing the operation of speed calculation unit 211 (FIG. 1) to detect a sudden change in the rotation speed. Speed ​​calculation unit 211 detects a sudden change in the rotation speed using sudden change determination unit 212 (FIG. 1).

[0047] When the process starts, the speed calculation unit 211 first determines in step S11 whether the difference in the electrical angular velocity per calculation cycle of the electrical angular velocity ω is equal to or greater than a predetermined threshold value. That is, the speed calculation unit 211 determines whether there is a sudden change in the rotation speed based on the magnitude of the change in the electrical angular velocity over time.

[0048] If the speed calculation unit 211 determines that the difference in electrical angular velocity is equal to or greater than the predetermined threshold value (YES in step S11), i.e., if it determines that there is a sudden change in the rotation speed, it then executes step S12. If the speed calculation unit 211 determines that the difference in electrical angular velocity is not equal to or greater than the predetermined threshold value (NO in step S11), i.e., if it determines that there is no sudden change in the rotation speed, it then executes step S15.

[0049] In step S12, the speed calculation unit 211 increments the count value of the number of sudden change detections by 1. After executing step S12, the speed calculation unit 211 then executes step S13.

[0050] In step S13, the speed calculation unit 211 determines whether the count value of the number of sudden change detections is equal to or greater than a predetermined threshold. If the speed calculation unit 211 determines that the count value of the number of sudden change detections is equal to or greater than the predetermined threshold (YES in step S13), the speed calculation unit 211 then executes step S14. If the speed calculation unit 211 determines that the count value of the number of sudden change detections is not equal to or greater than the predetermined threshold (NO in step S13), the speed calculation unit 211 returns to step S11 and executes step S11 and subsequent steps again.

[0051] In step S14, the speed calculation unit 211 confirms the detection of a sudden change in the rotation speed and sets the sudden change determination flag FL1 to ON (1). After executing step S14, the speed calculation unit 211 ends the series of processes.

[0052] In step S15, the speed calculation unit 211 resets the count value of the number of sudden change detections to 0. After executing step S15, the speed calculation unit 211 returns to step S11 and executes step S11 and subsequent steps again.

[0053] As described above, the speed calculation unit 211 counts the number of sudden change detections, then determines whether a sudden change in rotation speed has been detected and sets FL1 to ON (1), thereby keeping FL1 at ON (1) until it determines whether the sudden change in rotation speed has been detected by the operation described below (Figure 3).

[0054] 3 is a flowchart showing the operation of speed calculation unit 211 (FIG. 1) to determine whether the sudden change in rotation speed has been canceled. Speed ​​calculation unit 211 determines whether the sudden change in rotation speed has been canceled using sudden change determination unit 212 (FIG. 1).

[0055] When the process starts, the speed calculation unit 211 first determines in step S21 whether the difference in the electrical angular velocity per calculation cycle of the electrical angular velocity ω is equal to or smaller than a predetermined threshold value. That is, the speed calculation unit 211 determines whether the sudden change in the rotation speed has been canceled based on the magnitude of the change in the electrical angular velocity over time.

[0056] If the speed calculation unit 211 determines that the difference in electrical angular velocity is equal to or less than the predetermined threshold value (YES in step S21), that is, if it determines that the sudden change in rotation speed has been canceled, it then executes step S22. If the speed calculation unit 211 determines that the difference in electrical angular velocity is not equal to or less than the predetermined threshold value (NO in step S21), that is, if it determines that the sudden change in rotation speed has not been canceled, it then executes step S25.

[0057] In step S22, the speed calculation unit 211 increments the count value of the number of sudden change cancellation determinations by 1. After executing step S22, the speed calculation unit 211 then executes step S23.

[0058] In step S23, the speed calculation unit 211 determines whether the count value of the number of sudden change cancellation determinations is equal to or greater than a predetermined threshold. If the speed calculation unit 211 determines that the count value of the number of sudden change cancellation determinations is equal to or greater than the predetermined threshold (YES in step S23), the speed calculation unit 211 then executes step S24. If the speed calculation unit 211 determines that the count value of the number of sudden change cancellation determinations is not equal to or greater than the predetermined threshold (NO in step S23), the speed calculation unit 211 returns to step S21 and executes step S21 and subsequent steps again.

[0059] In step S24, the speed calculation unit 211 confirms that the sudden change in the rotation speed has been canceled, and sets the sudden change determination flag FL1 to OFF (0). After executing step S24, the speed calculation unit 211 ends the series of processes.

[0060] In step S25, the speed calculation unit 211 resets the count value of the number of sudden change cancellation determinations to 0. After executing step S25, the speed calculation unit 211 returns to step S21 and executes step S21 and subsequent steps again.

[0061] As described above, the speed calculation unit 211 counts the number of times the sudden change cancellation judgment is made, and then determines that the sudden change in rotation speed has been canceled and sets FL1 to OFF (0), thereby keeping FL1 at OFF (0) until the detection of the sudden change in rotation speed is determined by the above-mentioned operation (Figure 2).

[0062] 2 and 3, the speed calculation unit 211 counts the number of sudden change detections, then determines that a sudden change in rotation speed has been detected, and sets FL1 to ON (1), and counts the number of sudden change cancellation determinations, then determines that a sudden change in rotation speed has been canceled, and sets FL1 to OFF (0). This prevents FL1 from hunting.

[0063] FIG. 4 is a functional block diagram showing the configuration of the speed calculation unit 211 (FIG. 1).

[0064] The speed calculation unit 211 includes an electrical angular speed calculation unit 211 a, a low-pass filter (LPF) 211 b, a switching unit 211 c, a rotation speed calculation unit 211 e, and a sudden change determination unit 212.

[0065] The electrical angular velocity calculation unit 211a calculates the electric angular velocity by using a predetermined relational expression (for example, ω １ = (2π / 360) × (dθ / dt)) to obtain the angular velocity ω １ Calculate.

[0066] The low-pass filter 211b is １ Filtering ω １ From the fundamental component ω １ｆ Extract.

[0067] The switching unit 211c changes ω according to the sudden change determination flag FL1 set by the sudden change determination unit. １ and ω １ｆ When FL1 is "0", the switching unit 211c selects either ω １ｆ When FL1 is "1", the switching unit 211c selects ω １ Select .

[0068] The rotation speed calculation unit 211e calculates the rotation speed ω １ and ω １ｆ Based on either one of the above, a predetermined relational expression (for example, N=ω １ (ω １ｆ ) / 2π) to calculate the motor rotation speed N.

[0069] FIG. 5 is a functional block diagram showing the configuration of the gain setting section in the current control section 202 (FIG. 1).

[0070] The gain setting section in the current control section 202 has a control frequency setting section 202a, a control response gain map 202b, a multiplier 202c, a switching section 202d, and a PI controller 202e.

[0071] The PI controller 202e is a PI controller used for feedback control of the d- and q-axis interlinkage magnetic fluxes as described above. In Fig. 4, the two PI controllers for the d- and q-axes are simplified and shown as one PI controller 202e.

[0072] The control frequency setting unit 202a sets a predetermined control response frequency F ｃ Set.

[0073] The control response gain map 202b is ｄ ＊ , Φ ｑ ＊ And, F ｃ and the control response angular frequency ω for gain setting ｃ１ Based on such table data, the control response gain map 202b calculates the correspondence between Φ ｄ ＊ , Φ ｑ ＊ Depending on ｃ ω ｃ１ Change to.

[0074] The multiplier 202c multiplies ω ｃ１ is multiplied by a constant (k), where k is greater than 1, for example 1.5.

[0075] The switching unit 202d changes ω according to the sudden change determination flag FL1 set by the sudden change determination unit 212. ｃ１ and kω ｃ１ Select either one of these to set the control response angular frequency ω ｃ When FL1 is "0", the switching unit 202d outputs ω ｃ１ When FL1 is "1", the switching unit 202d selects kω １ Select ω ｃ Based on this, the proportional gain (K Ｐ ) and integral gain (K Ｉ ) is set (K Ｐ , K Ｉ∝ω ｃ : For example, K Ｐ =ω ｃ L.K. Ｉ =ω ｃ R (L and R are the motor inductance and winding resistance, respectively).

[0076] In this way, when the rotation speed changes suddenly, the control response is improved by making the value of the control response gain larger than the preset value, so that the SVPWM control unit 204 and the 3-pulse control unit 205 can operate in response to the sudden change in the rotation speed.

[0077] In this embodiment, Φ ｄ ＊ , Φ ｑ ＊ Depending on ω ｃ１ is variable, but ω ｃ１ may be a fixed value. ｃ１ By making it variable, it is possible to expand the range of torque in which good control response can be obtained.

[0078] FIG. 6 is a functional block diagram showing a partial configuration of the control mode switching unit 208 (FIG. 1).

[0079] The control mode switching unit 208 includes a magnetic flux increment setting unit 208a, an adder 208b, a switching unit 208c, an adder-subtractor 208d, and a comparison unit 208e.

[0080] The SVPWM / 3-pulse control section 245 corresponds to the above-mentioned SVPWM control section 204 or 3-pulse control section 205. As will be described later, the SVPWM control section 204 and the 3-pulse control section 205 are switched based on the modulation rate.

[0081] The switching unit 203a, the one-pulse control unit 206, and the switching unit 203a are included in the voltage control unit 203 (FIG. 1).

[0082] The magnetic flux increment setting unit 208a determines Φ ｄ The increment of d-axis magnetic flux Φ to be added to ｄ０ Set.

[0083] The adder 208b calculates Φ ｄ Φ ｄ０ Add.

[0084] The switching unit 208c switches between Φ ｄ , and Φ ｄ and Φ ｄ０ When FL1 is "0", the switching unit 208c selects and outputs either of the sums of Φ ｄ When FL1 is "1", the switching unit 202d selects Φ ｄ and Φ ｄ０ Select the additional value.

[0085] The adder / subtractor 208d calculates Φ ｄ ＊ and the d-axis magnetic flux value (Φ ｄ , or Φ ｄ and Φ ｄ０ the difference value ΔΦ ｄ Calculate.

[0086] The comparison unit 208e calculates ΔΦ ｄ a predetermined difference threshold (ΔΦ) ｔｈ Compared with ΔΦ ｄ (ΔΦ) ｔｈ The comparison unit 208e determines whether ΔΦ ｄ (ΔΦ) ｔｈ If it is determined that the ｄ ≧(ΔΦ) ｔｈ ), switching control signal S ｃ The comparison unit 208e sets the control unit switching flag FL2 to "1". ｄ (ΔΦ) ｔｈ If it is determined that it is not greater than (ΔΦ ｄ <(ΔΦ) ｔｈ ), switching control signal S ｃ The control unit switching flag FL2 is set to "0."

[0087] When FL2 is "1", the switching unit 203a selects the 1-pulse control unit 206. When FL2 is "0", the switching unit 203a selects the SVPWM / 3-pulse control unit 245.

[0088] In this embodiment, the d-axis current is a negative value due to the MTPA control, so Φ ｄ ＊ , Φ ｄis a negative value. d-axis magnetic flux increment Φ ｄ０ is a positive value. (ΔΦ ｄ ) ｔｈ is either a positive or negative value or a zero value. In this case, if FL1 is "1", as described above, the condition for switching from the SVPWM / 3-pulse control unit 245 to the 1-pulse control unit 206 is ΔΦ ｄ =Φ ｄ ＊ -Φ ｄ ≧(ΔΦ) ｔｈ is.

[0089] This switching condition is -Φ ｄ ≧-Φ ｄ ＊ + (ΔΦ) ｔｈ If we express this in terms of the magnitude of the magnetic flux, we get |Φ ｄ |≧|-Φ ｄ ＊ + (ΔΦ) ｔｈ |, so as mentioned above, Φ ｄ The size of Φ ｄ ＊ and (ΔΦ) ｔｈ The switching condition is that the signal level is equal to or greater than a predetermined threshold value set by

[0090] If the rotation speed changes suddenly, Φ ｄ Φ ｄ０ is added, so the switching condition is |Φ ｄ |≧|-Φ ｄ ＊ + (ΔΦ) ｔｈ +Φ ｄ０ That is, in effect, Φ ｄ This makes it easier to switch from the one-pulse control unit 206 to the SVPWM control unit 204 or the three-pulse control unit 205, and also makes it easier to maintain the control unit selected by the voltage control unit 203 at the SVPWM control unit 204 or the three-pulse control unit 205.

[0091] FIG. 7 is a functional block diagram showing a partial configuration of the control mode switching unit 208 (FIG. 1).

[0092] The control mode switching unit 208 has a section A that operates during normal operation of the PM motor 10, and sections B and C that operate when the rotation speed suddenly changes.

[0093] In part A, the comparison unit 208g and the comparison unit 208h respectively use the modulation factor threshold M ｔｈＡ and M ｔｈＢ (M ｔｈＡ >M ｔｈＢ ) is compared with the modulation factor M passed through the low-pass filter 208f (LPF).

[0094] As described above, the modulation factor M is calculated in the current control section 202 (FIG. 1).

[0095] When M increases, the switching flag FL3, which is generated by the logical sum gate 208p and the logical product gate 208o and is Sc output from the logical product gate 208o, becomes M=M ｔｈＡ When FL3 is "0" or "1", the switching unit 203b selects the 3-pulse control unit 205 and the SVPWM control unit 204 in the SVPWM / 3-pulse control unit 245, respectively. Therefore, M=M ｔｈＡ In this state, the selection target of the switching unit 203 a shown in FIG. 6 is switched from the SVPWM control unit 204 to the 3-pulse control unit 205 .

[0096] When M decreases, the switching flag FL3 is set to M=M ｔｈＢ It transitions from "1" to "0" at M = M ｔｈＢ In this state, the selection target of the switching unit 203 a shown in FIG. 6 is switched from the 3-pulse control unit 205 to the SVPWM control unit 204 .

[0097] In this way, the comparison unit 208g and comparison unit 208h, which have different threshold values, and the OR gate 208i (OR), form a comparison unit with hysteresis, which prevents hunting from occurring when switching between the SVPWM control unit 204 and the 3-pulse control unit 205.

[0098] In part C, the comparison unit 208l and the comparison unit 208m respectively use the modulation factor threshold M ｔｈＣ and M ｔｈＤ (M ｔｈＡ >M ｔｈＢ >M ｔｈＣ >M ｔｈＤ) is compared with a modulation factor M that is not passed through a low-pass filter 208f (LPF) in order to increase responsiveness to sudden changes in the rotation speed. When FL1 is "0", the switching unit 208n selects the comparing unit 208m. When FL1 is "1", the switching unit 208n selects the comparing unit 208l.

[0099] As a result, if there is no sudden change in the rotation speed of the PM motor 10, even if M fluctuates slightly, M≦M ｔｈＤ In this case, the selection target of the switching unit 203 a ( FIG. 6 ) is held in the SVPWM control unit 204 .

[0100] In addition, when the rotation speed of the PM motor 10 suddenly changes, the threshold value is set to M ｔｈＤ From M ｔｈｃ , the selection target of the switching unit 203a (FIG. 6) is more likely to be held by the SVPWM control unit 204. ｔｈｃ is M ｔｈＤ More than M ｔｈＡ Since the threshold is close to M ｔｈＡ and the OR gate 208k, makes it difficult to switch to the 3-pulse control unit 205. This prevents hunting from occurring when the rotation speed of the PM motor 10 suddenly changes.

[0101] The present invention is not limited to the above-described embodiments, but includes various modifications. For example, the above-described examples have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to those including all of the described configurations. Furthermore, it is possible to add, delete, or replace part of the configuration of each example with other configurations.

[0102] For example, the control lines and signal lines in the drawings are those that are considered necessary for the explanation, and not all control lines and signal lines are necessarily shown for implementing the present invention.

[0103] In the above-described embodiment, the d- and q-axis interlinkage magnetic fluxes of the PM motor 10 are used as the controlled variables. The d- and q-axis interlinkage magnetic fluxes are also state quantities that represent the operating state of the PM motor 10. Instead of the d- and q-axis interlinkage magnetic fluxes, the d- and q-axis currents of the PM motor 10 may be used as the controlled variables. In this case, the d- and q-axis interlinkage magnetic fluxes are state quantities.

[0104] Instead of the MTPA control, a flux-weakening control may be applied.

[0105] An overmodulation control mode may be applied instead of the three-pulse control mode, and a carrier (triangular wave, etc.) comparison type PWM control may be applied instead of the SVPWM control mode.

[0106] The control device 200 is not limited to a microcomputer, and may be configured by an FPGA or the like.

[0107] The semiconductor switching elements constituting the inverter circuit are not limited to IGBTs, but may also be power MOSFETs or the like.

[0108] 10: PM motor, 20: inverter circuit, 30: smoothing capacitor, 40: DC power supply, 70: current sensor, 80: voltage detector, 90: rotation detector, 200: control device, 201: current command value calculation unit, 202: current control unit, 202a: control frequency setting unit, 202b: control response gain map, 202c: multiplier, 202d: switching unit, 202e: PI controller, 202e, 203: voltage control unit, 203a: switching unit, 204: SVPWM control unit, 205: 3-pulse control unit, 206: 1-pulse control unit, 207: PWM gate signal generation unit, 208: control mode switching unit, 208a: magnetic flux increment setting unit, 208b: adder, 208c: switching unit, 208d: adder / subtractor, 208e: comparison unit, 208f: low-pass filter, 208g: comparison unit, 208h: comparison unit, 208i: logical sum gate, 208j: comparison unit, 208k: logical sum gate, 208l: comparison unit, 208m: comparison unit, 208n: switching unit, 208o: logical product gate, 208p: logical product gate, 209: current detection unit, 210: rotational position detection unit, 211: speed calculation unit, 211a: electrical angular velocity calculation unit, 211b: low-pass filter, 211c: switching unit, 211e: rotation speed calculation unit, 212: sudden change determination unit, 245: SVPWM / 3-pulse control unit

Claims

1. A motor control device that uses a power conversion device to drive and control an electric motor, comprising: a control mode switching unit that switches among a plurality of control modes for driving and controlling the electric motor when a predetermined state quantity exceeds a predetermined threshold; and a filter unit that filters the electrical angular velocity of the electric motor, wherein when a rate of change of the electrical angular velocity becomes equal to or greater than a predetermined value, the filtering by the filter unit is stopped and the predetermined threshold is raised.

2. A motor control device according to claim 1, wherein the predetermined state quantity is a d-axis interlinkage magnetic flux of the motor.

3. A motor control device according to claim 2, wherein the control mode switching unit selects a one-pulse control mode from among the plurality of control modes when the d-axis interlinkage magnetic flux is equal to or greater than the predetermined threshold value.

4. An electric motor control device according to claim 2, wherein the control mode switching unit selects the three-pulse control mode or the PWM control mode from among the plurality of control modes when the d-axis interlinkage magnetic flux is less than the predetermined threshold value.

5. An electric motor control device according to claim 4, wherein the control mode switching unit selects the three-pulse control mode or the PWM control mode based on a modulation factor.

6. An electric motor control device according to claim 1, further comprising means for suppressing hunting in the determination result as to whether or not the rate of change of the electrical angular velocity is equal to or greater than the predetermined value.

7. An electric motor control device according to claim 1, characterized in that when the rate of change of the electrical angular velocity becomes equal to or greater than a predetermined value, the value of the control response gain is increased to a value greater than a preset value.

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