Inverter control device

Abstract

The purpose of the present invention is to easily reduce voltage error due to dead time and suppress torque shock. An inverter control device (100) controls, by pulse width modulation, a switching operation of an inverter (10) that converts a DC voltage into an AC voltage and applies the AC voltage to a motor (3). An inverter control device (100) according to an embodiment 1 is provided with a dead time compensation unit (183) that performs dead time compensation for compensating for an error in the output voltage of an inverter (10) caused by the dead time of the inverter (10). A dead time compensation unit (183) performs dead time compensation on the basis of a difference ([theta] vi) between a current phase angle ([theta] i) indicating a phase angle for outputting a current of a motor (3) and a voltage phase angle ([theta] v) for outputting a voltage corresponding to the current.

Description

Technical Field

[0001] The invention relates to an inverter control device. Background Art

[0002] Inverter control devices that control the switching action of an inverter that converts a DC voltage into an AC voltage and applies it to an AC motor by pulse width modulation (hereinafter referred to as "PWM") are widely used. In such inverter control devices, in order to make the AC motor rotate at a high speed, there is a known technology for operating the inverter in an overmodulation region where the voltage command value of the inverter's output voltage exceeds the maximum output level of the sine wave. At this time, the inverter control device is operated by a single pulse control mode or a three-pulse control mode that generates a single pulse or three pulses in each fundamental wave period of the inverter's output voltage. The inverter control device can switch these control modes according to the operating area of ​​the AC motor.

[0003] In the inverter, when the upper and lower arms are switched, a dead time is set to disconnect the upper and lower arms to prevent short circuit. As a result, an error (hereinafter referred to as "voltage error") is generated between the output voltage of the inverter and its voltage command value. The voltage error generated by the dead time may cause a torque shock in which the motor does not output the torque as instructed when the inverter control device switches the control mode. Therefore, it is important to reduce the voltage error generated by the dead time to prevent the generation of torque shock.

[0004] Patent Document 1 discloses a technique for performing dead time compensation by correcting a phase threshold used for generating a switching command for controlling on and off of a switching element of an inverter using a dead time compensation phase in a phase reference synchronous control mode. Prior art literature Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2011-15566 Summary of the invention Technical problem to be solved by the invention

[0006] In the technology disclosed in Patent Document 1, since the dead time compensation phase is calculated based on the detection signal of the current supplied from the inverter to the motor and the fundamental frequency of the voltage command value, it is necessary to perform current polarity calculation at the switching timing. That is, in the technology disclosed in Patent Document 1, high-speed current detection is required to perform dead time compensation, and the voltage error caused by the dead time cannot be easily reduced.

[0007] The present invention has been made in view of the above circumstances, and an object of the present invention is to easily reduce a voltage error caused by a dead time and suppress a torque shock. Technical solutions to technical problems

[0008] In order to solve the above technical problems, the inverter control device of the present invention controls the switching action of the inverter that converts DC voltage into AC voltage and applies it to the AC motor through pulse width modulation, including a dead time compensation unit that compensates for the error in the output voltage of the inverter caused by the dead time of the inverter, and the dead time compensation unit performs the dead time compensation based on the difference between the current phase angle representing the phase angle of the current used to output the AC motor and the voltage phase angle used to output the voltage corresponding to the current. Effects of the Invention

[0009] According to the present invention, it is possible to easily reduce a voltage error caused by a dead time and suppress a torque shock. Problems, structures, and effects other than those described above will become more apparent from the following description of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a configuration diagram of a motor drive system including the inverter control device according to the first embodiment. Figure 2 This is a diagram showing the configuration of a three-pulse single-pulse calculation unit when the current phase angle and voltage phase angle are used as input. Figure 3 This is a configuration diagram of a three-pulse single-pulse operation unit when a current command value and a voltage command value are used as input. Figure 4 This is an explanatory diagram of a voltage waveform when a voltage error due to a dead time does not occur. Figure 5 1 is an explanatory diagram of the calculation contents of the dead time compensation unit when (1) Δα<θvi<α is satisfied. Figure 6 This is an explanatory diagram of the calculation contents of the dead time compensation unit when (2) α+Δα<θvi<π-α is satisfied. Figure 7 This is an explanatory diagram of the calculation contents of the dead time compensation unit when (3) π-α+Δα<θvi<π is satisfied. Figure 8 This is an explanatory diagram of the calculation contents of the dead time compensation unit when (4) π+Δα<θvi<π+α is satisfied. Fig. 9 1 and 2 are diagrams for explaining the calculation contents of the dead time compensating unit 183 when (5) π+α+Δα<θvi<2π-α is satisfied. Fig.101 and 2 are diagrams for explaining the calculation contents of the dead time compensating unit 183 when (6) 2π-α+Δα<θvi<2π is satisfied. Fig.11 This is a table showing the relationship between the difference between the voltage phase angle and the current phase angle, the amplitude error, and the phase angle error. Fig.12 yes Figure 1 An explanatory diagram of the effects of the inverter control device shown. Fig.13 This is a configuration diagram of a three-pulse single-pulse calculation unit included in the inverter control device according to the second embodiment. Fig.14 This is a table showing the relationship between the difference between the voltage phase angle and the current phase angle and the phase angle error. Fig.15 This is a configuration diagram of an inverter control device according to the third embodiment. DETAILED DESCRIPTION

[0011] Hereinafter, embodiments of the present invention will be described using the drawings. In addition, unless otherwise specified, structures marked with the same reference numerals in each embodiment have the same functions in each embodiment, and description thereof will be omitted.

[0012] [Implementation Method 1] use Figures 1 to 12 , the inverter control device 100 according to the first embodiment is described. Figure 1 1 is a block diagram of a motor drive system 1 including an inverter control device 100 according to the first embodiment.

[0013] The motor drive system 1 is connected to a battery 2 and includes an inverter 10 (inverter power unit), an inverter control device 100 , and an AC motor 3 (hereinafter also referred to as “motor 3 ”).

[0014] The battery 2 is a DC voltage source of the inverter 10. The DC voltage Vdc of the battery 2 (hereinafter also referred to as "power supply voltage Vdc") is converted into a three-phase AC voltage of variable voltage and variable frequency by the inverter 10, and applied to the motor 3. The motor 3 is a synchronous motor that is rotationally driven by applying a three-phase AC voltage. The rotation position sensor 4 is mounted on the motor 3 to control the phase of the three-phase AC voltage applied from the inverter 10 according to the phase of the induced voltage of the motor 3. The rotation position sensor 4 is constituted by, for example, a rotary transformer composed of an iron core and a winding. Alternatively, the rotation position sensor 4 may also be constituted by a GMR sensor or a rotation position sensor using a Hall element.

[0015] The inverter control device 100 is a device for controlling the inverter 10. The inverter control device 100 is composed of, for example, a microcomputer. The inverter control device 100 can realize various functions of the inverter control device 100 by executing a predetermined program in the microcomputer. Alternatively, the inverter control device 100 can also use a hardware circuit such as a logic IC or FPGA to realize a part or all of the various functions of the inverter control device 100.

[0016] The inverter control device 100 includes various functions such as a current command unit 110 , a current control unit 120 , a current detection unit 130 , a rotation position detection unit 140 , a PWM pulse generation unit 150 , a gate circuit 160 , an SVPWM operation unit 170 , and a three-pulse single pulse operation unit 180 .

[0017] The rotational position detection unit 140 detects the rotational position θp, which is the position of the rotor of the motor 3 , based on the output signal of the rotational position sensor 4 .

[0018] The current detection unit 130 obtains three-phase current detection values ​​Iuvw (Iu, Iv, Iw) flowing through the motor 3 from the current sensor Ict. The current detection unit 130 performs three-phase to two-phase conversion on these current detection values ​​based on the rotation position θp detected by the rotation position detection unit 140, thereby detecting dq axis current detection values ​​Idq (Id, Iq).

[0019] The inverter control device 100 has a current control function for controlling the output of the motor 3. The current command unit 110 calculates the dq-axis current command value Idq* (Id*, Iq*) based on the torque command value T* output from the upper control device (not shown). The current command unit 110 outputs the calculated dq-axis current command value Idq* to the current control unit 120, the SVPWM operation unit 170, and the three-pulse single-pulse operation unit 180. In addition, the current command unit 110 can also calculate the current phase angle θi representing the phase angle of the dq-axis current command value Idq* based on the dq-axis current command value Idq*. The current command unit 110 can output the calculated current phase angle θi to the current control unit 120, the SVPWM operation unit 170, and the three-pulse single-pulse operation unit 180.

[0020] The current control unit 120 calculates the dq-axis voltage command value Vdq* (Vd*, Vq*) as the voltage command value of the output voltage of the inverter 10 corresponding to the dq-axis current command value Idq* output from the current command unit 110. Specifically, the current control unit 120 calculates the dq-axis voltage command value Vdq* so that the dq-axis current command value Idq* output from the current command unit 110 is consistent with the dq-axis current detection value Idq detected by the current detection unit 130. The current control unit 120 outputs the calculated dq-axis voltage command value Vdq* to the SVPWM operation unit 170 and the three-pulse single-pulse operation unit 180. In addition, the current control unit 120 can calculate the voltage phase angle θv representing the phase angle of the dq-axis voltage command value Vdq* based on the dq-axis voltage command value Vdq*. The current control unit 120 outputs the calculated voltage phase angle θv to the SVPWM operation unit 170 and the three-pulse single-pulse operation unit 180.

[0021] The three-pulse single-pulse operation unit 180 calculates a modulation wave based on the voltage command value in the output voltage of the inverter 10. That is, the three-pulse single-pulse operation unit 180 is a modulation wave operation unit that calculates a modulation wave corresponding to the output voltage of the inverter 10. Specifically, the three-pulse single-pulse operation unit 180 calculates a three-phase voltage command value Vuvw* (Vu*, Vv*, Vw*) by performing a two-phase to three-phase conversion on the dq-axis voltage command value Vdq* output from the current control unit 120 using the rotation position θp. Among the three-phase voltage command values ​​Vuvw*, Vu* is a U-phase voltage command value, Vv* is a V-phase voltage command value, and Vw* is a W-phase voltage command value. Then, the three-pulse single-pulse operation unit 180 generates a modulation wave signal duvw representing the modulation wave represented by the three-phase voltage command value Vuvw*, and outputs it to the PWM pulse generation unit 150. In addition, at this time, the three-pulse single-pulse operation unit 180 can express the three-phase voltage command value Vuvw* by selecting a modulation method other than sinusoidal wave modulation, for example, a trapezoidal wave or a waveform in which a sinusoidal wave is superimposed with a higher harmonic of a specified order, or other waveform other than a sinusoidal wave.

[0022] In addition, the three-pulse single-pulse operation unit 180 may calculate the modulation factor MF of the output voltage of the inverter 10 based on the power supply voltage Vdc and the dq-axis voltage command value Vdq* output from the current control unit 120, and output the modulation factor MF to the PWM pulse generation unit 150 instead of the modulation wave signal duvw. Furthermore, the three-pulse single-pulse operation unit 180 may calculate both the modulation wave signal duvw and the modulation factor MF, and output them to the PWM pulse generation unit 150. That is, the three-pulse single-pulse operation unit 180 can calculate at least one of the modulation wave signal duvw and the modulation factor MF.

[0023] The PWM pulse generating unit 150 performs three-phase pulse width modulation (PWM) based on the modulation wave signal duvw or the modulation rate MF calculated by the three-pulse single pulse calculating unit 180, and generates a PWM pulse signal P for controlling the switching operation of the inverter 10. For example, the PWM pulse generating unit 150 compares the carrier wave that changes periodically according to the carrier wave frequency fc with the modulation wave signal duvw. And, based on the comparison result, the PWM pulse generating unit 150 determines the position (phase) of the rising edge and the falling edge (hereinafter also referred to as "pulse edge") of each pulse by a known method, and can generate the PWM pulse signal P. In this case, the PWM pulse generating unit 150 can set the carrier wave frequency fc to be constant, or can change the carrier wave frequency fc according to the rotation speed of the motor 3. Alternatively, the PWM pulse generating unit 150 can also generate the PWM pulse signal P by directly calculating the position of each pulse edge based on the modulation rate MF without using the carrier wave and the modulation wave signal duvw. Alternatively, the PWM pulse generating unit 150 can also generate the PWM pulse signal P by other methods. In any case, the PWM pulse generating unit 150 may adopt any method as long as it can generate the PWM pulse signal P for controlling the inverter 10 at each predetermined control period based on the voltage command value in the output voltage of the inverter 10 .

[0024] The gate circuit 160 outputs a drive signal DR corresponding to the PWM pulse signal P to the inverter 10. The inverter 10 has a plurality of semiconductor switch elements corresponding to each of the three-phase AC voltages, and each semiconductor switch element is turned on / off controlled by the drive signal DR. Therefore, the output voltage of the inverter 100 is adjusted according to the control of the inverter control device 100.

[0025] The SVPWM operation unit 170 calculates a modulation wave when using the space vector pulse width modulation (SVPWM) control mode. That is, the SVPWM operation unit 170 is a modulation wave operation unit that calculates a modulation wave corresponding to the output voltage of the inverter 10. Specifically, the SVPWM operation unit 170 performs a two-phase to three-phase conversion of the dq axis voltage command value Vdq* output from the current control unit 120 using the rotation position θp to calculate the three-phase voltage command value Vuvw*. In addition, the SVPWM operation unit 170 performs dead time compensation on the three-phase voltage command value Vuvw* using the dq axis current command value Idq*. Then, the SVPWM operation unit 170 calculates the duty ratio duvw by dividing the three-phase voltage command value Vuvw* after the dead time compensation by the power supply voltage Vdc. Then, the SVPWM operation unit 170 outputs the calculated duty ratio duvw to the PWM pulse generation unit 150.

[0026] In addition, in the above, through Figure 1Although the configuration example of the motor drive system 1 is described in which the current of the motor 3 is controlled based on the dq-axis current command value Idq* from the current command unit 110, the same can also be applied when other control methods are adopted. Figure 1 For example, when controlling the rotation speed of the motor 3, the inverter control device 100 calculates the motor rotation speed ωr based on the time change of the rotation position θp, and generates a voltage command value or a current command value to match the speed command value from the upper control device. In addition, when controlling the output torque of the motor 3, the inverter control device 100 uses the relationship or mapping between the motor current (Idq) and the motor torque to generate the current command value (Idq*).

[0027] Figure 2 1 is a diagram showing the configuration of the three-pulse single-pulse calculation unit 180 when the current phase angle θi and the voltage phase angle θv are input. Figure 3 1 is a diagram showing the configuration of the three-pulse single-pulse calculation unit 180 when the current command value Idq* and the voltage command value Vdq* are input.

[0028] like Figure 2 and Figure 3 As shown, the three-pulse single-pulse operation unit 180 includes a dead time compensation unit 183, an arc angle operation unit 184, a phase angle operation unit 185 and a duty cycle operation unit 186. Figure 3 The three-pulse single-pulse calculation unit 180 shown includes a modulation rate / voltage phase angle calculation unit 181 and a current phase angle calculation unit 182 .

[0029] Figure 2 An example is shown in which the current phase angle θi obtained by calculating the amplitude and phase angle using a table for the torque command is directly input to the three-pulse single-pulse operation unit 180, and the voltage phase angle θv obtained using voltage phase control is directly input to the three-pulse single-pulse operation unit 180. Figure 3 FIG. 1 shows an example in which the dq axis current command value Idq* output from the current command unit 110 is input to the three-pulse single-pulse operation unit 180, and the dq axis voltage command value Vdq* output from the current control unit 120 is input to the three-pulse single-pulse operation unit 180. The inverter control device 100 may adopt Figure 2 The three-pulse single-pulse operation unit 180 and Figure 3 Any one of the three-pulse single-pulse operation units 180 shown.

[0030] Next, the inverter control device 100 adopts Figure 3 The three-pulse single-pulse operation unit 180 shown is described by taking the case where the switch operation is controlled in the three-pulse control mode as an example.

[0031] The modulation factor and voltage phase angle calculation unit 181 calculates the modulation factor MF and the voltage phase angle θv based on the dq axis voltage command value Vdq* of the output voltage of the inverter 10. Specifically, the modulation factor and voltage phase angle calculation unit 181 calculates the square root of the sum of the squares of the d axis voltage command value Vd* and the q axis voltage command value Vq* output from the current control unit 120. Then, the modulation factor and voltage phase angle calculation unit 181 divides the calculated square root of the sum of the squares by the power supply voltage Vdc, thereby calculating the modulation factor MF.

[0032] The modulation rate and voltage phase angle calculation unit 181 uses equation 1 to calculate the voltage phase angle θv from the dq-axis voltage command value Vdq*. [Mathematical formula 1]

[0033] The current phase angle calculation unit 182 calculates the current phase angle θi based on the dq axis current command value Idq* of the current flowing through the motor 3. Specifically, the current phase angle calculation unit 182 uses Equation 2 to calculate the current phase angle θi from the dq axis current command value Idq*. [Mathematical formula 2]

[0034] The current phase angle calculation unit 182 can calculate the current phase angle θi based on the dq axis current detection value Idq, which is the detection value of the current flowing to the motor 3. Similarly, the modulation factor and voltage phase angle calculation unit 181 calculates the modulation factor MF and the voltage phase angle θv based on the detection value of the output voltage of the inverter 10.

[0035] The dead time compensator 183 performs dead time compensation for compensating the output voltage error caused by the dead time Δα of the inverter 10. Specifically, the dead time compensator 183 performs dead time compensation when the switching operation of the inverter 10 is controlled by at least one of the single pulse control mode and the three-pulse control mode.

[0036] The single-pulse control mode is a control mode that generates a single pulse in each fundamental wave period of the output voltage of the inverter 10. The single-pulse control mode is used in a region where the fundamental wave frequency of the output voltage of the inverter 10 is high. The three-pulse control mode is a control mode that generates three pulses in each fundamental wave period of the output voltage of the inverter 10. The three-pulse control mode is used in a region where the fundamental wave frequency of the output voltage of the inverter is medium. In addition, the SVPWM control mode is a control mode that compares the carrier wave and the modulating wave and generates a pulse according to their magnitude. The SVPWM control mode is used in a region where the fundamental wave frequency of the output voltage of the inverter 10 is low.

[0037] The dead time compensation unit 183 performs dead time compensation based on the difference θvi (=θv-θi) between the current phase angle θi representing the phase angle of the current for outputting the motor 3 and the voltage phase angle θv for outputting the voltage corresponding to the current. Specifically, the dead time compensation unit 183 calculates at least one of the voltage error caused by the dead time Δα, that is, the amplitude error ΔA and the phase angle error Δθ of the output voltage as the dead time compensation amount. The three-pulse single-pulse calculation unit 180 uses the amplitude error ΔA calculated as the dead time compensation amount to correct the modulation rate MF used in the calculation of the firing angle α of the output voltage. In addition, the three-pulse single-pulse calculation unit 180 uses the phase angle error Δθ calculated as the dead time compensation amount to correct the phase angles θ1 and θ2 of the output voltage. In this way, the dead time compensation unit 183 can perform dead time compensation.

[0038] The firing angle α is the pulse width to be adjusted when setting the number of pulses per fundamental wave period of the output voltage. There is a relationship as shown in Mathematical Formula 3 between the firing angle α and the modulation factor MF. [Mathematical formula 3]

[0039] Therefore, the firing angle α can be expressed by the modulation rate MF as shown in Mathematical Formula 4. [Formula 4]

[0040] The dead time compensation unit 183 calculates the amplitude error ΔA and the phase angle error Δθ as the dead time compensation amount based on the relationship between the firing angle α and the difference θvi. Figures 4 to 11 , the calculation contents of the amplitude error ΔA and the phase angle error Δθ of the dead time compensation unit 183 are described in detail.

[0041] Figure 4 This is an explanatory diagram of a voltage waveform when a voltage error due to a dead time does not occur.

[0042] When no voltage error is generated due to the dead time, the switching timings α1 to α4 in the interval [0, 2π] can be expressed as in Math. 5 for the firing angle α. [Mathematical formula 5] α1=α α2=π-α α3=π+α α4=2π-α

[0043] For the switching timings α1 to α4, Fourier coefficients an and bn when the output voltage of the inverter 10 is Fourier series expanded using the power supply voltage Vdc, the firing angle α, and the dead time Δα can be expressed as in Math. [Mathematical formula 6] b n =0

[0044] The amplitude A of the output voltage of the inverter 10 can be expressed as in Formula 7 using the Fourier coefficients an and bn of Formula 6. [Mathematical formula 7]

[0045] The phase angle error Δθ of the output voltage of the inverter 10 can be expressed as in Formula 8 when no voltage error is generated due to the dead time. [Mathematical formula 8] Δθ=tan -1 (b n / a n )=0

[0046] The dead time compensating unit 183 obtains the above-mentioned equations 5 to 8 based on the relationship between the firing angle α and the difference θvi, thereby calculating the amplitude error ΔA and the phase angle error Δθ as the dead time compensation amount.

[0047] Figure 5 1 is an explanatory diagram of the calculation contents of the dead time compensating unit 183 when (1) Δα<θvi<α is satisfied.

[0048] Figure 5 The upper part (a) of shows the voltage waveform before dead time compensation. For the arc angle α, the switching timings α1 to α4 in the interval [0, 2π] of a fundamental wave cycle can be calculated according to Figure 4 And mathematical formula 5 is expressed as mathematical formula 9. [Mathematical formula 9] α1=α α2=π-α α3=π+α α4=2π-α

[0049] In reality, there is a phase difference between the output voltage of the inverter 10 and the current flowing to the motor 3. The inventors have noticed that the amplitude error ΔA and the phase angle error Δθ vary according to the range of the difference θvi between the voltage phase angle θv and the current phase angle θi. Specifically, as the range of the difference θvi between the voltage phase angle θv and the current phase angle θi, the amplitude error ΔA and the phase angle error Δθ represent different values ​​in each of the cases (1) to (6) shown in the mathematical formula 10. Therefore, the dead time compensation unit 183 calculates the amplitude error ΔA and the phase angle error Δθ according to each of the cases (1) to (6) shown in the mathematical formula 10. [Formula 10] (1)Δα<θvi<α (2)α+Δα<θvi<π-α (3)π-α+Δα<θvi<π (4)π+Δα<θviπ+α (5)π+α+Δα<θvi<2π-α (6)2π-α+Δα<θvi<2π

[0050] When (1) Δα<θvi<α is satisfied, the relationship between the output voltage of the inverter 10 and the current flowing to the motor 3 before dead time compensation is as follows: Figure 5 The output voltage after dead time compensation when (1) Δα<θvi<α is Figure 5 The waveform is as shown in the lower part (c). Figure 5 The switching timings α0 to α5 shown in the lower section (c) of can be expressed as in Formula 11 using the firing angle α and the dead time Δα. [Mathematical formula 11] α0=Δα α1=α+Δα α2=π-α α5=π+Δα α3=π+α+Δα α4=2π-α

[0051] The dead time compensation unit 183 calculates the correction amounts of the modulation rate and the phase angle, i.e., the amplitude error ΔA and the phase angle error Δθ, so that at the switching timings α0 to α5, the average modulation rate and the phase angle in one fundamental wave cycle are consistent with those when no voltage error due to the dead time occurs.

[0052] Specifically, the dead time compensating unit 183 can calculate the Fourier coefficients an and bn as shown in Equation 12 using the power supply voltage Vdc, the firing angle α, and the dead time Δα. [Mathematical formula 12]

[0053] Therefore, the dead time compensating unit 183 can calculate the amplitude A of the output voltage of the inverter 10 as shown in Formula 13 using the Fourier coefficients an and bn of Formula 12. [Mathematical formula 13]

[0054] As a case where no voltage error due to dead time occurs, use Figure 4 Comparing the above-described equations 7 and 8, the dead time compensating unit 183 can calculate the amplitude error ΔA and the phase angle error Δθ when (1) Δα<θvi<α as in equation 14. [Mathematical formula 14] Δθ=0

[0055] Figure 6 1 and 2 are diagrams for explaining the calculation contents of the dead time compensating unit 183 when (2) α+Δα<θvi<π-α is satisfied.

[0056] When (2) α+Δα<θvi<π-α is satisfied, the relationship between the output voltage of the inverter 10 and the current flowing to the motor 3 before dead time compensation is as follows: Figure 6 The output voltage after dead time compensation when (2) α+Δα<θvi<π-α is Figure 6 The waveform is as shown in the lower part (c). Figure 6 The switching timings α0 to α5 shown in the lower section (c) of can be expressed as shown in Formula 15 using the firing angle α and the dead time Δα. [Mathematical formula 15] α0=Δα α1=α α2=π-α α5=π+Δα α3=π+α α4=2π-α

[0057] The dead time compensating unit 183 can calculate the Fourier coefficients an and bn as shown in Formula (16). [Formula 16]

[0058] Therefore, the dead time compensating unit 183 can calculate the amplitude A of the output voltage of the inverter 10 as shown in Formula 17 using the Fourier coefficients an and bn of Formula 16. [Mathematical formula 17]

[0059] Use Figure 4 Comparing the above-described equations 7 and 8, the dead time compensating unit 183 can calculate the amplitude error ΔA and the phase angle error Δθ when (2) α+Δα<θvi<π-α as in equation 18. [Mathematical formula 18] ΔA=0 Δθ=Δα

[0060] Figure 7 1 and 2 are diagrams for explaining the calculation contents of the dead time compensating unit 183 when (3) π-α+Δα<θvi<π is satisfied.

[0061] When (3)π-α+Δα<θvi<π is satisfied, the relationship between the output voltage of the inverter 10 and the current flowing to the motor 3 before dead time compensation is as follows: Figure 7 The output voltage after dead time compensation when (3)π-α+Δα<θvi<π is Figure 7 The waveform is as shown in the lower part (c). Figure 7 The switching timings α0 to α5 shown in the lower section (c) can be expressed as shown in Formula 19 using the firing angle α and the dead time Δα. [Mathematical formula 19] α0=Δα α1=α α2=π-α+Δα α5=π+Δα α3=π+α α4=2π-α+Δα

[0062] The dead time compensating unit 183 can calculate the Fourier coefficients an and bn as shown in Equation 20. [Mathematical formula 20]

[0063] Therefore, the dead time compensating unit 183 can calculate the amplitude A of the output voltage of the inverter 10 as shown in Formula 21 using the Fourier coefficients an and bn of Formula 20. [Mathematical formula 21]

[0064] Use Figure 4 Comparing the above-described equations 7 and 8, the dead time compensating unit 183 can calculate the amplitude error ΔA and the phase angle error Δθ when (3) π-α+Δα<θvi<π as in equation 22. [Mathematical formula 22]

[0065] Figure 8 1 and 2 are diagrams for explaining the calculation contents of the dead time compensating unit 183 when (4) π+Δα<θvi<π+α is satisfied.

[0066] When (4)π+Δα<θvi<π+α is satisfied, the relationship between the output voltage of the inverter 10 and the current flowing to the motor 3 before dead time compensation is as follows: Figure 8 The output voltage after dead time compensation when (4)π+Δα<θvi<π+α is Figure 8 The waveform is as shown in the lower part (c). Figure 8 The switching timings α1 to α4 shown in the lower section (c) can be expressed as in Formula 23 using the firing angle α and the dead time Δα. [Mathematical formula 23] α1=α α2=π-α+Δα α3=π+α α4=2π-α+Δα

[0067] The dead time compensating unit 183 can calculate the Fourier coefficients an and bn as shown in Equation 24. [Mathematical formula 24]

[0068] Therefore, the dead time compensating unit 183 can calculate the amplitude A of the output voltage of the inverter 10 as shown in Formula 25 using the Fourier coefficients an and bn of Formula 24. [Mathematical formula 25]

[0069] Use Figure 4 Comparing the above-described equations 7 and 8, the dead time compensating unit 183 can calculate the amplitude error ΔA and the phase angle error Δθ when (4) π+Δα<θvi<π+α as in equation 26. [Mathematical formula 26]

[0070] Fig. 9 1 and 2 are diagrams for explaining the calculation contents of the dead time compensating unit 183 when (5) π+α+Δα<θvi<2π-α is satisfied.

[0071] When (5)π+α+Δα<θvi<2π-α is satisfied, the relationship between the output voltage of the inverter 10 and the current flowing to the motor 3 before dead time compensation is as follows: Fig. 9 The output voltage after dead time compensation when (5)π+α+Δα<θvi<2π-α is Fig. 9 The waveform is as shown in the lower part (c). Fig. 9 The switching timings α1 to α4 shown in the lower section (c) can be expressed as in Formula 27 using the firing angle α and the dead time Δα. [Mathematical formula 27] α1α+Δα α2=π-α+Δα a3=π+α+Δα α4=2π-α+Δα

[0072] The dead time compensating unit 183 can calculate the Fourier coefficients an and bn as shown in Formula 28. [Mathematical formula 28]

[0073] Therefore, the dead time compensating unit 183 can calculate the amplitude A of the output voltage of the inverter 10 as shown in Formula 29 using the Fourier coefficients an and bn of Formula 28. [Mathematical formula 29]

[0074] Use Figure 4 Comparing the above-described equations 7 and 8, the dead time compensating unit 183 can calculate the amplitude error ΔA and the phase angle error Δθ when (5) π+α+Δα<θvi<2π-α as in equation 30. [Math 30] ΔA=0

[0075] Fig.10 1 and 2 are diagrams for explaining the calculation contents of the dead time compensating unit 183 when (6) 2π-α+Δα<θvi<2π is satisfied.

[0076] When (6) 2π-α+Δα<θvi<2π is satisfied, the relationship between the output voltage of the inverter 10 and the current flowing to the motor 3 before dead time compensation is as follows: Fig.10 The output voltage after dead time compensation when (6) 2π-α+Δα<θvi<2π is Fig.10 The waveform is as shown in the lower part (c). Fig.10 The switching timings α1 to α4 shown in the lower section (c) can be expressed as in equation 31 using the firing angle α and the dead time Δα. [Mathematical formula 31] α1=α+Δα α2=π-α α3=π+α+Δα α4=2π-α

[0077] The dead time compensating unit 183 can calculate the Fourier coefficients an and bn as shown in Equation 32. [Math 32]

[0078] Therefore, the dead time compensating unit 183 can calculate the amplitude A of the output voltage of the inverter 10 as shown in Formula 33 using the Fourier coefficients an and bn of Formula 32. [Mathematical formula 33]

[0079] Use Figure 4 Comparing the above-described equations 7 and 8, the dead time compensating unit 183 can calculate the amplitude error ΔA and the phase angle error Δθ when (6) 2π-α+Δα<θvi<2π as in equation 34. [Math 34]

[0080] Fig.11 This is a table showing the relationship between the difference θvi between the voltage phase angle θv and the current phase angle θi, the amplitude error ΔA, and the phase angle error Δθ. Fig.11 The table summarizes the Figures 5 to 10 The amplitude error ΔA and phase angle error Δθ calculated in each case.

[0081] In use Figures 5 to 10 In each of the cases (1) to (6) described above, the amplitude error ΔA and the phase angle error Δθ are as follows: Fig.11 The three-pulse single-pulse operation unit 180 uses the same Fig.11 The amplitude error ΔA corresponding to the range of the difference θvi shown in FIG. 1 is used to correct the modulation factor MF used in the calculation of the firing angle α of the output voltage. Fig.11 The phase angle error Δθ corresponding to the range of the difference θvi shown is used to correct the phase angles θ1 and θ2 of the output voltage. As a result, the three-pulse single-pulse operation unit 180 can output an output voltage that takes the dead time into account from the inverter 10 for the requested voltage. Fig.11As shown, when the amplitude error ΔA is zero, the three-pulse single-pulse operation unit 180 does not need to correct the modulation factor MF. Similarly, when the phase angle error Δθ is zero, the three-pulse single-pulse operation unit 180 does not need to correct the phase angles θ1 and θ2 of the output voltage.

[0082] In addition, for example, in the interval [0, Δα], for the amplitude error ΔA and the phase angle error Δθ between (6) 2π-α+Δα<θvi<2π and (1) Δα<θvi<α, the dead time compensation unit 183 may perform linear interpolation based on the amplitude error ΔA and the phase angle error Δθ calculated in each range. Alternatively, since Δα is a small amount, the dead time compensation unit 183 may set the amplitude error ΔA and the phase angle error Δθ between (6) 2π-α+Δα<θvi<2π and (1) Δα<θvi<α to zero.

[0083] The firing angle calculation unit 184 calculates the firing angle α of the output voltage of the inverter 10 based on the amplitude error ΔA calculated as the dead time compensation amount and the modulation factor MF. Specifically, the firing angle calculation unit 184 adds the amplitude error ΔA calculated as the dead time compensation amount as an operation amount to the modulation factor MF, and calculates the firing angle α based on the modulation factor MF to which the amplitude error ΔA is added. Specifically, the firing angle calculation unit 184 can calculate the firing angle α using the mathematical formula 35. [Mathematical formula 35]

[0084] The phase angle calculation unit 185 calculates the phase angles θ1 and θ2 of the output voltage of the inverter 10 based on the phase angle error Δθ calculated as the dead time compensation amount and the electrical angle θp of the motor 3. The phase angle θ1 represents the phase angle of the output voltage at the next control timing. The phase angle θ2 represents the phase angle of the output voltage at the next control timing. Specifically, the phase angle calculation unit 185 uses the electrical angle deviation ωtc per carrier cycle calculated based on the electrical angular velocity ω of the motor 3 and the carrier cycle tc as a sampling delay amount of the phase angle. Then, the phase angle calculation unit 185 adds the phase angle error Δθ calculated as the dead time compensation amount to the previous voltage phase angle θv as the operation amount, and calculates the phase angles θ1 and θ2. In detail, when the rotation speed of the motor 3 is positive, the phase angle calculation unit 185 can calculate the phase angles θ1 and θ2 using mathematical formula 36. [Mathematical formula 36]

[0085] When the rotation speed of the motor 3 is negative, the phase angle calculation unit 185 can calculate the phase angles θ1 and θ2 by changing (+π / 2) on the right side of the mathematical formula 36 to (-π / 2). In addition, the mathematical formula 36 represents the phase angles θ1 and θ2 of one phase (for example, the U phase) in the three-phase voltage. When calculating the phase angles θ1 and θ2 of other phases (for example, the V phase or the W phase) in the three-phase voltage, the phase angle calculation unit 185 can calculate the phase angles θ1 and θ2 of the other phases by shifting the phase angles θ1 and θ2 calculated by the mathematical formula 36 by 120 degrees.

[0086] The duty ratio calculation unit 186 calculates the duty ratio duvw in each phase of the three-phase voltage and determines the position of each pulse edge (switching timing) based on the firing angle α of the output voltage calculated by the firing angle calculation unit 184 and the phase angles θ1 and θ2 of the output voltage calculated by the phase angle calculation unit 185. Then, the duty ratio calculation unit 186 outputs the calculated duty ratio duvw and the position of each pulse edge to the PWM pulse generation unit 150.

[0087] The PWM pulse generator 150 generates a PWM pulse signal P corresponding to the calculated duty ratio duvw and the position of each pulse edge, and outputs it to the gate circuit 160. The gate circuit 160 outputs a drive signal DR corresponding to the PWM pulse signal P to the inverter 10. Each semiconductor switch element of the inverter 10 is turned on / off controlled by the drive signal DR. Thus, the output voltage of the inverter 10 is adjusted.

[0088] Fig.12 Yes Description Figure 1 FIG. 1 is a diagram showing the effects of the inverter control device 100 .

[0089] As described above, the inverter control device 100 of the first embodiment is a device that controls the switching operation of the inverter 10 that converts a DC voltage into an AC voltage and applies the AC voltage to the motor 3 by pulse width modulation. The inverter control device 100 of the first embodiment includes a dead time compensation unit 183 that performs dead time compensation to compensate for the error in the output voltage of the inverter 10 caused by the dead time of the inverter 10. The dead time compensation unit 183 performs dead time compensation based on the difference θvi between the current phase angle θi representing the phase angle for outputting the current of the motor 3 and the voltage phase angle θv for outputting the voltage corresponding to the current.

[0090] Therefore, if Fig.12As shown, the inverter control device 100 of embodiment 1 can perform dead time compensation for the requested voltage, and can make the output voltage of the inverter 10 consistent with the requested voltage. Therefore, the inverter control device 100 of embodiment 1 can reduce the voltage error caused by the dead time. Moreover, the dead time compensation unit 183 of embodiment 1 can perform dead time compensation based on the difference θvi between the voltage phase angle θv that can be calculated according to the dq axis voltage command value Vdq* and the current phase angle θi that can be calculated according to the dq axis current command value Idq*. Therefore, the inverter control device 100 of embodiment 1 can easily perform dead time compensation without performing high-speed current detection as in the past. Therefore, the inverter control device 100 of embodiment 1 can easily reduce the voltage error caused by the dead time when switching from the SVPWM control mode to the three-pulse control mode, and suppress the torque shock.

[0091] The inverter control device 100 of the first embodiment further includes: a modulation factor and voltage phase angle calculation unit 181, which calculates the modulation factor MF and the voltage phase angle θv of the output voltage; and a current phase angle calculation unit 182, which calculates the current phase angle θi. The inverter control device 100 of the first embodiment includes: an arc angle calculation unit 184, which calculates the arc angle α of the output voltage; and a phase angle calculation unit 185, which calculates the phase angles θ1 and θ2 of the output voltage. The dead time compensation unit 183 calculates at least one of the amplitude error ΔA and the phase angle error Δθ of the output voltage generated due to the dead time as the dead time compensation amount. The arc angle calculation unit 184 calculates the arc angle α based on the amplitude error ΔA and the modulation factor MF calculated as the dead time compensation amount. The phase angle calculation unit 185 calculates the phase angles θ1 and θ2 based on the phase angle error Δθ calculated as the dead time compensation amount.

[0092] Thus, even if the amplitude error ΔA and the phase angle error Δθ vary according to the range of the difference θvi, the inverter control device 100 of the first embodiment can calculate the firing angle α and the phase angles θ1 and θ2 to correct the amplitude error ΔA and the phase angle error Δθ. Therefore, the inverter control device 100 of the first embodiment can appropriately compensate for the voltage error caused by the dead time even if the voltage error varies according to the phase difference between the output voltage of the inverter 10 and the current flowing to the motor 3. Therefore, the inverter control device 100 of the first embodiment can easily and reliably reduce the voltage error caused by the dead time and reliably suppress the torque shock.

[0093] Thus, in the inverter control device 100 according to the first embodiment, the dead time compensating unit 183 performs dead time compensation when the switching operation is controlled in the three-pulse control mode.

[0094] Thus, the inverter control device 100 of the first embodiment can easily reduce the voltage error caused by the dead time and suppress the torque shock when controlled by the three-pulse control mode. In particular, the inverter control device 100 of the first embodiment can suppress the torque shock generated when switching from the SVPWM control mode to the three-pulse control mode as in the past. In particular, the inverter control device 100 of the first embodiment can suppress the torque shock generated when switching from the three-pulse control mode to the SVPWM control mode. Therefore, the inverter control device 100 of the first embodiment can achieve the stabilization of the operation of the motor 3.

[0095] [Implementation Method 2] use Fig.13 and Fig.14 Next, an inverter control device 100 according to Embodiment 2 will be described. In the inverter control device 100 according to Embodiment 2, description of the same configuration and operation as those in Embodiment 1 will be omitted. Fig.13 It is a configuration diagram of the three-pulse single-pulse calculation unit 180 included in the inverter control device 100 according to the second embodiment. Fig.14 This is a table showing the relationship between the difference θvi between the voltage phase angle θv and the current phase angle θi, and the phase angle error Δθ.

[0096] In the second embodiment, a case where the inverter control device 100 controls the switching operation using the single pulse control mode is described as an example.

[0097] Even in the case of the single pulse control mode, when the Fourier coefficients an and bn are calculated in the same manner as in the case of the three pulse control mode described in the first embodiment, the relationship between the range of the difference θvi and the phase angle error Δθ is as follows: Fig.14 That is, Fig.14 As shown, in the case of the single pulse control mode, there is no need to calculate the amplitude error ΔA as the dead time compensation amount, and there is no need to correct the modulation factor MF.

[0098] Therefore, the dead time compensating unit 183 of the second embodiment calculates only the phase angle error Δθ as the dead time compensation amount based on the difference θvi. The phase angle calculating unit 185 of the second embodiment calculates the phase angles θ1 and θ2 of the output voltage based on the phase angle error Δθ calculated as the dead time compensation amount and the electrical angle θp of the motor 3, similarly to the first embodiment. On the other hand, the firing angle calculating unit 184 of the second embodiment calculates the firing angle α of the output voltage based on the uncorrected modulation factor MF.

[0099] Therefore, the inverter control device 100 according to the second embodiment does not need to calculate the amplitude error ΔA as the dead time compensation amount, and does not need to correct the modulation factor MF, so the control logic can be simplified compared with the first embodiment. Therefore, the inverter control device 100 according to the second embodiment can more easily reduce the voltage error caused by the dead time and suppress the torque shock.

[0100] Furthermore, in the inverter control device 100 according to the second embodiment, the dead time compensating unit 183 performs dead time compensation when the switching operation is controlled in the single pulse control mode.

[0101] Thus, the inverter control device 100 of the second embodiment can easily reduce the voltage error caused by the dead time and suppress the torque shock when controlled by the single pulse control mode. In particular, the inverter control device 100 of the second embodiment can suppress the torque shock generated when switching from the three-pulse control mode to the single pulse control mode. The inverter control device 100 of the second embodiment can also suppress the torque shock generated when switching from the single pulse control mode to the three-pulse control mode. Therefore, the inverter control device 100 of the second embodiment can further achieve the stabilization of the operation of the motor 3.

[0102] [Implementation method 3] use Fig.15 Next, an inverter control device 100 according to Embodiment 3 will be described. In the inverter control device 100 according to Embodiment 3, description of the same configuration and operation as those in Embodiment 1 will be omitted. Fig.15 This is a configuration diagram of an inverter control device 100 according to the third embodiment.

[0103] In the third embodiment, the reduction of the voltage error caused by the dead time is not only used to suppress the torque shock but also used to estimate the position of the rotor of the motor 3 .

[0104] The inverter control device 100 of the third embodiment includes an induced voltage estimation axis deviation calculation unit 141 and a speed phase estimation unit 142 instead of the rotation position detection unit 140 (or as a part of the rotation position detection unit 140). The other configurations of the inverter control device 100 of the third embodiment are the same as those of the first embodiment.

[0105] The induced voltage estimation axis deviation calculation unit 141 estimates the induced voltage E0 of the motor 3 based on the dq axis voltage command value Vdq*, the dq axis current detection value Idq, and the speed command value ωr* that commands the motor speed. Then, the induced voltage estimation axis deviation calculation unit 141 calculates the axis deviation estimation value Δθp based on the phase of the estimated induced voltage E0. The speed phase estimation unit 142 estimates the rotation position θp, which is the position of the rotor of the motor 3, based on the magnitude |E0| of the induced voltage E0 and the axis deviation estimation value Δθp.

[0106] Japanese Patent No. 3411878 discloses a method of estimating the rotational position θp from the induced voltage E0 estimated using the dq-axis voltage command value Vdq*. The inverter control device 100 of the third embodiment can refer to the method disclosed in Japanese Patent No. 3411878.

[0107] In the case where a voltage error is generated due to the dead time, in the above-mentioned method of estimating the rotation position θp using the dq-axis voltage command value Vdq*, the voltage error generated due to the dead time will be superimposed on the phase of the induced voltage E0 as an error, resulting in a deterioration in the estimation accuracy of the rotation position θp. However, the inverter control device 100 of the third embodiment can reduce the voltage error generated due to the dead time as in the first embodiment, and thus can improve the estimation accuracy of the rotation position θp. This is also the case in the flux estimation and torque estimation of the motor 3 using the dq-axis voltage command value Vdq*. The inverter control device 100 of the third embodiment can improve the estimation accuracy of each of the flux estimation and torque estimation of the motor 3 using the dq-axis voltage command value Vdq*.

[0108] [other] In addition, the present invention is not limited to the above-mentioned embodiments, but also includes various modified examples. For example, the above-mentioned embodiments are detailed descriptions for the purpose of explaining the present invention in an understandable manner, and the present invention is not necessarily limited to including all the structures described. In addition, a part of the structure of a certain embodiment may be replaced with the structure of another embodiment, and in addition, the structure of another embodiment may be added to the structure of a certain embodiment. In addition, other structures may be added, deleted, or replaced with a part of the structure of each embodiment.

[0109] In addition, the above-mentioned structures, functions, processing parts, processing units, etc. may be partially or entirely implemented in hardware, for example, by designing an integrated circuit. In addition, the above-mentioned structures, functions, etc. may also be implemented in software by interpreting and executing programs that implement the respective functions through a processor. Information such as programs, tables, files, etc. that implement the respective functions may be stored in a memory or a recording device such as a hard disk, SSD (solid state drive), or a recording medium such as an IC card, SD card, or DVD.

[0110] In addition, although control lines and information lines necessary for explanation are shown, this does not limit the display to all control lines and information lines necessary for the product. In fact, it can be considered that almost all structures are connected to each other. Description of symbols

[0111] 3…motor (AC motor), 10…inverter, 100…inverter control device, 181…modulation rate·voltage phase angle calculation unit, 182…current phase angle calculation unit, 183…dead time compensation unit, 184…arc angle calculation unit, 185…phase angle calculation unit.

Claims

1. An inverter control device, which controls the switching action of an inverter that converts a DC voltage into an AC voltage and applies the AC voltage to an AC motor by pulse width modulation, characterized in that: A dead time compensation unit is included, the dead time compensation unit performs dead time compensation for compensating for an error in the output voltage of the inverter caused by the dead time of the inverter, The dead time compensating unit performs the dead time compensation based on a difference between a current phase angle indicating a phase angle for outputting a current of the AC motor and a voltage phase angle for outputting a voltage corresponding to the current.

2. The inverter control device according to claim 1, characterized in that: Also includes: a modulation rate and voltage phase angle calculation unit for calculating the modulation rate and the voltage phase angle of the output voltage; a current phase angle calculation unit, the current phase angle calculation unit calculating the current phase angle; an arc firing angle calculation unit, the arc firing angle calculation unit calculating the arc firing angle of the output voltage; and a phase angle calculation unit for calculating a phase angle of the output voltage; The dead time compensation unit calculates at least one of an amplitude error and a phase angle error of the output voltage caused by the dead time as a dead time compensation amount. The firing angle calculation unit calculates the firing angle based on the amplitude error calculated as the dead time compensation amount and the modulation rate. The phase angle calculation unit calculates the phase angle based on the phase angle error calculated as the dead time compensation amount.

3. The inverter control device according to claim 1, characterized in that: The dead time compensation unit performs the dead time compensation when the switching operation is controlled by at least one of a single pulse control mode and a three-pulse control mode.

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