Power conversion device and electric vehicle system having the same

Abstract

The present invention provides a power conversion device that does not require adaptation work and can suppress current beats regardless of the operating state of the motor. The power conversion device includes: an inverter (1) that converts a DC voltage into an AC voltage to drive an AC motor (2); and beat compensation units (46) and (49) that suppress the current beat component of the output current of the inverter (1). The beat compensation units (46) and (49) include: beat extraction units (50), (51) and (52) that calculate the beat component of the output current of the inverter (1); and beat compensation voltage calculation units (53) and (54) that estimate the beat compensation voltage based on the beat component calculated by the beat extraction units (50), (51) and (52). Based on the beat compensation voltage estimated by the beat compensation voltage calculation units (53) and (54), the current beat component of the output current of the inverter (1) is suppressed.

Description

Technical Field

[0001] The present invention relates to a power conversion device and an electric vehicle system having the power conversion device. Background Art

[0002] In power conversion devices for AC motors, due to errors in sensor signal values ​​used for control, output voltage errors of inverters, etc., a current beat phenomenon occurs in which low-frequency components slower than the fundamental frequency are superimposed on the phase current flowing through the motor. This phenomenon causes pulsation of the motor's output torque and deterioration of efficiency.

[0003] In addition, since the phase current is offset by the current beat, a current larger than the amplitude value of the phase current flows. Generally, since the inverter is equipped with an overcurrent protection function, there is also a problem that the overcurrent protection is activated by the current beat, causing the inverter to stop.

[0004] In particular, when the switching frequency of the inverter is not sufficiently high relative to the fundamental frequency of the current flowing through the motor, a voltage difference occurs between the positive side output and the negative side output of the inverter, resulting in a current beat.

[0005] When a high-rotation motor is driven, the fundamental frequency of the current flowing through the motor is high and the impedance of the motor is small, so a large current beat occurs.

[0006] As a countermeasure against the current beat, the following method has been proposed.

[0007] Patent document 1 describes the following method: as a current beat suppression device, the pulsating components on the dq axes are extracted by a high-pass filter (HPF), and the current beat components of each phase are calculated by performing a three-phase transformation on them, and the three-phase voltage instructions are compensated by performing proportional integral operation (PI compensation) on the calculated current beat components.

[0008] Patent document 2 describes the following method: subtracting the value obtained by performing three-phase transformation of the dq-axis current command value from the actual value of the three-phase current to extract the current beat component, and using PLL (Phase Locked Loop) to convert the current beat component into amplitude and phase to suppress the current beat.

[0009] Patent document 3 describes the following method: extract the pulsating components in the rotating coordinate system through a high-pass filter (HPF), transform them into three phases, thereby calculating the current beat components of each phase, and compensate the three-phase voltage instructions by performing proportional operation (P compensation) on the current beat components.

[0010] Patent Document 4 describes a method in which a DC voltage of an inverter is detected by a voltage sensor, a ripple frequency is calculated based on the detected voltage signal, and a dq-axis voltage command value is compensated using a controller that amplifies only the ripple frequency component.

[0011] Prior art literature

[0012] Patent Literature

[0013] Patent Document 1: Japanese Patent Application Publication No. 2010-063335

[0014] Patent Document 2: Japanese Patent Application Publication No. 2017-017817

[0015] Patent Document 3: Japanese Patent Application Publication No. 2004-104898

[0016] Patent Document 4: Japanese Patent Application Publication No. 2018-113770 Summary of the invention

[0017] Problem that the invention aims to solve

[0018] However, in the method described in Patent Document 1, HPF and PI compensator are used to extract the current beat component, so the cutoff frequency of HPF and the gain of PI compensator need to be adapted. This is the main reason for the increase in development man-hours of the power conversion device. In addition, in the low rotation range where the current beat is difficult to generate, when the frequency of the assumed current beat component is approximately equal to the fundamental frequency, the fundamental component may be detected as the current beat component. In this case, it is necessary to stop the compensation action for the current beat component, which may affect the action of the current control system that is indispensable for the torque control of the motor.

[0019] In addition, in the method described in Patent Document 2, a current beat component is converted into amplitude and phase using a PLL. In this method, when the frequency of the current beat component is unknown, there is a problem that the response is slow.

[0020] In addition, in the method described in Patent Document 3, since a P compensator is used, it is theoretically impossible to completely suppress the current beat component.

[0021] Furthermore, in the method described in Patent Document 4, the current beat phenomenon caused by the pulsation of the DC voltage of the inverter can be suppressed, but the current beat phenomenon caused by other reasons cannot be suppressed.

[0022] An object of the present invention is to realize a power conversion device that does not require adaptation work and can suppress current beats regardless of the operating state of a motor, and an electric vehicle system including the same.

[0023] Technical means of solving problems

[0024] In order to achieve the above object, the present invention is constructed as follows.

[0025] In a power conversion device, there is: an inverter, which converts a DC voltage into an AC voltage to drive an AC motor; and a beat compensator, which suppresses the current beat component of the output current of the inverter, the beat compensator having: a beat extraction unit, which calculates the beat component of the output current of the inverter; and a beat compensation voltage calculation unit, which estimates the beat compensation voltage based on the beat component calculated by the beat extraction unit, and the power conversion device suppresses the current beat component of the output current of the inverter based on the beat compensation voltage estimated by the beat compensation voltage calculation unit.

[0026] In an electric vehicle system, there are: an electric motor that drives the vehicle and a motor control device that controls the electric motor, the motor control device having a power conversion device, the power conversion device having: an inverter that converts a DC voltage into an AC voltage to drive an AC motor; and a beat compensation unit that suppresses a current beat component of an output current of the inverter, the beat compensation unit having: a beat extraction unit that calculates the beat component of the output current of the inverter; and a beat compensation voltage calculation unit that estimates a beat compensation voltage based on the beat component calculated by the beat extraction unit, the power conversion device suppresses the current beat component of the output current of the inverter based on the beat compensation voltage estimated by the beat compensation voltage calculation unit.

[0027] Effects of the Invention

[0028] According to the present invention, it is possible to realize a power conversion device that does not require adaptation work and can suppress current beats regardless of the operating state of the motor, and an electric vehicle system including the same.

[0029] The other objects, structures, and effects than those described above will become clear from the following description of the embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a diagram showing a schematic circuit configuration of the power conversion device according to the first embodiment.

[0031] Figure 2 This is a processing block diagram for explaining the processing of the controller of the first embodiment.

[0032] Figure 3 The diagram shows three-phase current waveforms (experimental waveforms) when a current beat occurs due to a voltage difference between a positive-side output and a negative-side output of an inverter.

[0033] Figure 4 This is an internal block diagram showing the processing contents of the beat suppression control unit of the first embodiment.

[0034] Figure 5 This is an internal block diagram showing the processing contents of the beat suppression control unit of the second embodiment.

[0035] Figure 6 It is a coordinate diagram for explaining the processing of the output adjustment processing unit in the second embodiment.

[0036] Figure 7 This is a schematic diagram of the electric vehicle system of the third embodiment. DETAILED DESCRIPTION

[0037] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In each of the drawings, the same reference numerals are used for the same elements, and repeated descriptions are omitted.

[0038] Example

[0039] (Example 1)

[0040] Figure 1 It is a diagram showing a schematic circuit configuration of a power conversion device according to the first embodiment of the present invention.

[0041] exist Figure 1 In the embodiment, the power conversion device of the electric motor 2 is mainly composed of an inverter 1, a battery 3, a controller 4 and the like.

[0042] The inverter 1 is a three-phase voltage type two-level inverter.

[0043] The motor 2 is connected to a driving mechanism of an electric vehicle system described later, and the vehicle is propelled by the rotation of the motor 2. The motor 2 of the first embodiment is an AC motor, and is a three-phase embedded magnet synchronous motor (IPMSM). The motor 2 is operated by the interaction between the magnetic flux generated by the permanent magnets provided on the rotor (not shown) and the magnetic field generated by the currents iu, iv, and iw flowing through the three-phase windings 5, 6, and 7 fixed to the armature. iu, iv, and iw are U-phase current, V-phase current, and W-phase current, respectively.

[0044] The motor 2 includes a magnetic pole position sensor 8. The magnetic pole position sensor 8 has a function of detecting the magnetic pole position of the rotor of the motor 2 as a rotation angle. The magnetic pole position sensor 8 outputs a magnetic pole position signal 9 (θ) and inputs it to the controller 4. The processing of the magnetic pole position signal 9 (θ) in the controller 4 will be described later. Figure 2 Provide explanation.

[0045] The current sensor 10 detects the current flowing through the windings 5, 6, and 7, and based on this, outputs a U-phase current sensor signal 11 (a signal representing the current iu), a V-phase current sensor signal 12 (a signal representing the current iv), and a W-phase current sensor signal 13 (a signal representing the current iw), and inputs them into the controller 4.

[0046] The current sensor signals 11, 12, 13 are also processed in the controller 4 using Figure 2 This will be explained later.

[0047] The inverter 1 includes switching elements 14, 15, 16, 17, 18, 19 and freewheeling diodes 20, 21, 22, 23, 24, 25. The switching elements 14 to 19 of the first embodiment are Si-IGBTs, each including a gate terminal, a collector terminal, and an emitter terminal. The freewheeling diodes 20 to 25 are connected between the collector terminal and the emitter terminal of each of the switching elements 14 to 19.

[0048] Regarding the flyback diodes 20 to 25, when the collector terminal of the switching elements 14 to 19 has a higher potential than the emitter terminal, a current flows through the flyback diodes 20 to 25, thereby preventing a high reverse voltage from being applied to the switching elements 14 to 19. The switching of the switching elements 14 to 19 between on and off is performed by gate drive signals 26, 27, 28, 29, 30, and 31 connected to the gate terminals of the respective switching elements 14 to 19.

[0049] The gate signal 32 consisting of six lines, which is the basis of each gate drive signal 26 to 31, is generated by the controller 4 and output to the gate drive circuit 35. The gate drive circuit 35 converts the gate signal 32 into a potential required for switching the switching elements 14, 15, 16, 17, 18, and 19 on and off, and outputs the gate drive signals 26, 27, 28, 29, 30, and 31. The generation of the gate signal 32 in the controller 4 will be used later. Figure 2 Provide explanation.

[0050] The emitter terminal of the switching element 14 and the collector terminal of the switching element 15 are connected to each other, and the connection point is connected to the winding 5 and the current iu flows through it. The emitter terminal of the switching element 16 and the collector terminal of the switching element 17 are connected to each other, and the connection point is connected to the winding 6 and the current iv flows through it. The emitter terminal of the switching element 18 and the collector terminal of the switching element 19 are connected to each other, and the connection point is connected to the winding 7 and the current iw flows through it. The collector terminals of the switching elements 14, 16, and 18 are connected to each other and connected to the high potential DC wiring 33. In addition, the emitter terminals of the switching elements 15, 17, and 19 are connected to each other and connected to the low potential DC wiring 34.

[0051] Thus, the controller 4 turns on and off the switching elements 14, 15, 16, 17, 18, and 19 at appropriate times based on the generated gate signal 32, controls the currents iu, iv, and iw flowing through the windings 5, 6, and 7, and realizes the rotation control of the motor 2. The gate signal 32 is in the form of a PWM (pulse width modulation) signal, so that the currents iu, iv, and iw become sinusoidal signals with phases that differ by 120 degrees from each other.

[0052] The voltage sensor 36 is connected to the high potential DC wiring 33 and the low potential DC wiring 34 to detect the potential difference therebetween. The potential difference between the high potential DC wiring 33 and the low potential DC wiring 34 is usually a high voltage of, for example, 100 V or more, so the voltage sensor 36 generates a DC voltage sensor signal 37 (Vdc) converted into a low voltage detectable by the controller 4 and inputs it to the controller 4.

[0053] The smoothing capacitor 38 included in the inverter 1 is connected between the high potential DC line 33 and the low potential DC line 34. The smoothing capacitor 38 has a function of suppressing pulsation of the DC voltage generated by the switching operation of the switching elements 14 to 19.

[0054] The high potential terminal of the battery 3 is connected to the high potential DC wiring 33, and the low potential terminal of the battery 3 is connected to the low potential DC wiring 34. Thus, the battery 3 operates as a DC power supply that supplies power to the inverter 1 and the motor 2.

[0055] A torque command 39 (T*) provided from a higher-level controller of the vehicle such as an ECU (Electronic Control Unit) is input to the controller 4. The controller 4 performs torque control of the electric motor 2 based on the torque command 39 (T*).

[0056] Figure 2 This is a processing block diagram for explaining the processing of the controller 4 according to the first embodiment of the present invention.

[0057] exist Figure 2 In the embodiment, the processing block of the controller 4 includes a current command operation unit 40, a three-phase two-phase conversion unit 41, a current control unit 42, a two-phase three-phase conversion unit 43, a speed operation unit 44, a PWM gate control signal generation unit (control signal generation unit) 45, a beat suppression control unit 46, a deviation calculator 47, and a deviation calculator 48. The current command operation unit 40, the three-phase two-phase conversion unit 41, the current control unit 42, the two-phase three-phase conversion unit 43, the deviation calculator 47, and the deviation calculator 48 form a three-phase voltage command value generation unit.

[0058] The controller 4 allows three-phase currents iu, iv, and iw to flow through the motor 2 to control rotation, but the so-called current vector control method is used inside the controller 4. This current vector control method performs processing by transforming the fixed coordinates of the three phases into a coordinate system of rotating coordinates of the two phases represented by the d-axis and the q-axis.

[0059] The current command calculation unit 40 calculates the d-axis current command value id* and the q-axis current command value iq*. The torque command 39 (T*), the rotational angular velocity ω, and the DC voltage sensor signal 37 (Vdc) are input to the current command calculation unit 40, and the d-axis current command value id* and the q-axis current command value iq* are calculated based on these inputs. The rotational angular velocity ω is calculated by the speed calculation unit 44 based on the magnetic pole position signal 9 (θ).

[0060] In a synchronous motor having magnetic saliency such as an IPMSM, the torque T depends on the current as shown in the following equation (1).

[0061] T=Pp·{φ+(Ld-Lq)id}·iq…(1)

[0062] However, in the formula (1), id is the d-axis current, iq is the q-axis current, Pp is the number of pole pairs, Ld is the d-axis inductance, Lq is the q-axis inductance, and Φ is the magnet flux.

[0063] The magnetic pole position signal 9 (θ) is input to the three-phase to two-phase conversion unit 41 and the two-phase to three-phase conversion unit 43 for conversion between the two-phase coordinates and the three-phase coordinates of the d-axis and q-axis.

[0064] The three-phase to two-phase converter 41 converts the current sensor signals 11 (iu), 12 (iv), and 13 (iw) into d-axis and q-axis coordinates based on the information of the magnetic pole position signal 9 (θ), and outputs the d-axis detection current id and the q-axis detection current iq.

[0065] The deviation calculator 47 calculates a deviation between the d-axis current command value id* output from the current command calculation unit 40 and the d-axis detected current id output from the three-phase to two-phase conversion unit 41 , and outputs the d-axis current deviation Δid to the current control unit 42 .

[0066] The deviation calculator 48 calculates a deviation between the q-axis current command value iq* output from the current command calculation unit 40 and the q-axis detection current iq output from the three-phase to two-phase conversion unit 41 , and outputs the q-axis current deviation Δiq to the current control unit 42 .

[0067] The current control unit 42 performs feedback control so that the d-axis differential current Δid and the q-axis current deviation Δiq, which represent the deviation between the command value as the target value and the measured value as the output value, become zero, and calculates and outputs the d-axis voltage command Vd* and the q-axis voltage command Vq* as voltage commands in order to update the output value. The feedback control in the current control unit 42 is performed, for example, by PI control.

[0068] The d-axis voltage command value Vd* and the q-axis voltage command value Vq* outputted from the current control unit 42 are inputted to the two-phase to three-phase conversion unit 43, which calculates and outputs three-phase voltage command values ​​Vu*, Vv*, and Vw* based on the magnetic pole position signal θ.

[0069] The beat suppression control unit 46 and the beat compensation amount subtraction unit 49 are processes related to the present invention, and are not used in normal current vector control.

[0070] Therefore, in normal current vector control, the three-phase voltage command values ​​Vu*, Vv*, and Vw*, which are outputs of the two-phase to three-phase conversion unit 43 , are input to the PWM gate control signal generation unit 45 without being processed in any way.

[0071] Then, in normal current vector control, the PWM gate control signal generating unit (control signal generating unit) 45 generates six gate signals 32 as PWM signals by comparing the three-phase voltage command values ​​Vu*, Vv*, Vw* with a carrier wave not shown, and outputs them to the gate drive circuit 35.

[0072] In the first embodiment, a so-called asynchronous PWM is adopted in which the switching frequency of the inverter 1 does not continuously change according to the speed (frequency) of the motor 2. Therefore, the frequency of the carrier (carrier frequency) does not continuously change according to the speed.

[0073] The above is the normal control process of the controller 4 .

[0074] Next, the generation principle of the current beat phenomenon which is the subject of the present invention will be sorted out.

[0075] The following factors can be cited as the main causes of the current beat.

[0076] (1) Caused by the pulsation of the inverter input DC voltage.

[0077] (2) Caused by errors in the current detection value used for current vector control, errors in the magnetic pole position signal and estimated value, and the electrical and mechanical structure of the motor.

[0078] (3) Caused by the voltage difference between the positive and negative outputs of the inverter.

[0079] Regarding (1), it is a phenomenon that the power pulsation when the system power is rectified into DC by a rectifier, which is likely to occur in a system connected to an AC power system, causes the AC current of the inverter to beat. The frequency of the current beat is uniquely determined based on the relationship between the pulsation frequency of the DC voltage and the fundamental frequency of the inverter. The technologies described in Patent Documents 2, 3, and 4 all target this phenomenon.

[0080] Regarding (2), Patent Document 1 states that it occurs when the modulation rate of the inverter is large, particularly in an overmodulation region or a rectangular wave drive region, and high-speed current vector control cannot be performed.

[0081] Unlike the phenomenon described in (1), the frequency of the current beat cannot be analytically determined.

[0082] Patent Document 1 targets this phenomenon.

[0083] The present invention targets the current beat phenomenon (3). (3) occurs when the carrier frequency is insufficient for the fundamental frequency. It occurs particularly prominently in a system where the voltage command value is updated for each carrier cycle in an asynchronous PWM. As with the phenomenon (2), the frequency of the current beat cannot be analytically determined.

[0084] Next, the configuration of the beat suppression processing and control system according to the first embodiment of the present invention will be described.

[0085] As described above, the beat suppression control unit 46 and the beat compensation amount subtraction unit 49 are added to the controller 4 .

[0086] The beat suppression control unit 46 is supplied with the phase currents iu, iv, iw from the current sensor 10 , and the beat suppression control unit 46 is supplied with the d-axis current command value id* and the q-axis current command value iq* from the current command calculation unit 40 .

[0087] In addition, the magnetic pole position signal 9 (θ) is provided from the magnetic pole position sensor 8 to the beat current suppression control unit 46, and the angular velocity ω is provided from the speed calculation unit 44 to the beat current suppression control unit 46. Then, the beat suppression control unit 46 detects the beat components of the three-phase currents iu, iv, and iw, and outputs the beat compensation voltages ΔVu**, ΔVv**, and ΔVw** to the beat compensation amount subtraction unit 49.

[0088] The beat compensation amount subtraction unit 49 subtracts the beat compensation voltages ΔVu**, ΔVv**, ΔVw** outputted by the beat suppression control unit 46 from the three-phase voltage command values ​​Vu*, Vv*, Vw* outputted by the two-phase to three-phase conversion unit 43, and calculates new three-phase voltage command values ​​(compensated three-phase voltage command values) Vu**, Vv**, Vw** inputted to the PWM gate control signal generation unit 45. The calculated compensated three-phase voltage command values ​​Vu**, Vv**, Vw** are outputted to the PWM gate control signal generation unit 45. Then, the gate signal 32 is generated by the PWM gate control signal generation unit 45, and is outputted to the gate drive circuit 35.

[0089] Figure 3 This means that Figure 1 The three-phase current waveform (experimental waveform) when a current beat occurs due to the phenomenon (3) described above, i.e., the voltage difference between the positive and negative outputs of the inverter in the power conversion device shown is a diagram showing an example when the fundamental frequency is 500 Hz.

[0090] Figure 3 The waveform shown in (A) shows the waveform before the current beat suppression. Figure 3 (B) shows the waveform after the current beat is suppressed by the embodiment 1 of the present invention. Figure 3 In (A) and (B), the U-phase, V-phase, and W-phase currents are shown from the top.

[0091] like Figure 3 As shown in (A), it can be confirmed that a current beat of about 40 Hz is generated relative to the fundamental frequency of the current of 500 Hz.

[0092] On the other hand, Figure 3 As shown in (B), it can be confirmed that the current beat is suppressed from the currents iu, iv, and iw at the fundamental frequency of 500 Hz.

[0093] Embodiment 1 of the present invention targets the current beat phenomenon caused by the above-mentioned factor (3), but even when the current beat is caused by the above-mentioned factors (1) and (2), the current beat can be suppressed.

[0094] Figure 4 This is an internal block diagram showing the processing contents of the beat suppression control unit 46 according to the first embodiment of the present invention.

[0095] exist Figure 4In the embodiment, the beat suppression control unit 46 includes a two-phase to three-phase conversion unit 50, a magnetic pole position correction unit 51, a subtractor 52, a motor inverse model unit 53, a low-pass filter 54, and a feedback loop 55. The two-phase to three-phase conversion unit 50, the magnetic pole position correction unit 51, and the subtractor 52 form a beat extraction unit. The beat extraction unit calculates the current beat component of the output current of the inverter 1.

[0096] When a current beat phenomenon occurs in the phase currents iu, iv, iw, the beat suppression control unit 46 estimates a disturbance voltage causing the current beat, and outputs beat compensation voltages (disturbance estimation voltages) ΔVu**, ΔVv**, ΔVw**.

[0097] The two-phase to three-phase conversion unit 50 calculates three-phase current command values ​​iu-, iv*, and iw* based on the d-axis current command value id* and the q-axis current command value iq* from the current command calculation unit 40 and the corrected magnetic pole position θ′ output from the magnetic pole position correction unit 51 .

[0098] The magnetic pole position correction unit 51 calculates the magnetic pole position correction angle Δθ using the angle correction gain Kω based on the angular velocity ω output from the speed calculation unit 44, adds it to the magnetic pole position signal 9 (θ) output from the magnetic pole position sensor 8, calculates the corrected magnetic pole position θ' and outputs it. The angle correction gain Kω is a time dimension and corrects the phase difference between the phase currents iu, iv, iw and the phase current command values ​​iu*, iv*, iw* caused by the detection delay of the current sensor 10, etc.

[0099] The subtractor 52 subtracts the phase current command values ​​iu*, iv*, iw* from the phase currents iu, iv, iw to extract current beat components Δiu, Δiv, Δiw.

[0100] The motor inverse model unit 53 receives the current beat components Δiu, Δiv, Δiw from the subtractor 52 and outputs disturbance estimation voltages ΔVu*, ΔVv*, ΔVw* that cause the current beats. The function of the motor inverse model unit 53 is represented by the transfer function G1(s) of the following equation (2).

[0101] G1(s)=K1s / (Tds+)+K0…(2)

[0102] However, in the above equation (2), s is the Laplace operator, Td is the pseudo differentiator time constant, and K1 and K0 are control gains.

[0103] In addition, since the pure inverse model includes a differential operation, the first term on the right side of the above equation (2) becomes a pseudo differentiator (high-pass filter).

[0104] The low-pass filter 54 removes noise superimposed on the disturbance estimated voltages ΔVu*, ΔVv*, ΔVw* output from the motor inverse model unit 53, and outputs beat compensation voltages ΔVu**, ΔVv**, ΔVw**. Since the noise component may be amplified by the motor inverse model unit 53, the low-pass filter 54 removes the noise component.

[0105] The function of the low-pass filter 54 is represented by the transfer function of the following equation (3).

[0106] G2(s)=1 / (TLs+1)…(3)

[0107] However, in the above equation (3), TL is the time constant of the low-pass filter. Usually, the time constant is set to TL>>Td.

[0108] The feedback loop 55 feeds back the beat compensation voltages ΔVu**, ΔVv**, ΔVw** to the input of the low-pass filter 54. Through this feedback loop, the beat current is completely suppressed by the beat suppression control, and even if ΔVu*, ΔVv*, ΔVw* is 0, the beat compensation voltages ΔVu**, ΔVv**, ΔVw** are kept output, so compensation can continue.

[0109] As described above, in the first embodiment of the present invention, the beat extracting unit extracts the current beat components Δiu, Δiv, Δiw from the three-phase current signals iu, iv, iw detected by the current sensor 10, converts the extracted current beat components Δiu, Δiv, Δiw into disturbance estimated voltages ΔVu*, ΔVv*, ΔVw* by the motor inverse model unit 53, removes noise by the low-pass filter 54, and estimates the beat compensation voltages ΔVu**, ΔVv**, ΔVw**. Then, the estimated beat compensation voltages ΔVu**, ΔVv**, ΔVw** are subtracted from the three-phase voltage command values ​​Vu*, Vv*, Vw* by the beat compensation amount subtracting unit 49 to compensate, and are provided to the PWM gate control signal generating unit 45 for driving the inverter 1. The gate signal 32 is provided from the PWM gate control signal generating unit 45 to the gate driving circuit 35, and the gate driving signals 26 to 31 are output to the inverter 1 for driving the motor 2.

[0110] Therefore, according to the first embodiment, it is possible to realize a power conversion device that does not require adaptation work and can suppress the current beat regardless of the operating state of the motor.

[0111] (Example 2)

[0112] Next, Example 2 of the present invention will be described.

[0113] Figure 5It is an internal block diagram showing the processing contents of the beat suppression control unit 46 according to the second embodiment of the present invention.

[0114] exist Figure 5 In the example shown, in Example 1 Figure 4 The internal block of the beat suppression control unit 46 shown in the figure is added with an output adjustment processing unit 56 and an output adjustment multiplier 57. The other configurations in the second embodiment are the same as those in the first embodiment, and thus illustration and detailed description thereof are omitted.

[0115] When the speed of the motor 2 is low and the frequency of the assumed current beat component is close to the fundamental frequency of the phase current, the beat suppression control unit 46 may not be able to accurately calculate the beat compensation voltage.

[0116] In addition, the speed of the motor 2 is very high, and the influence of the detection delay and operation delay of the three-phase current iu, iv, iw becomes large, and the subtractor 52 cannot extract the correct beat current. In this case, the operation of the current control unit 42 may be affected, and the output torque of the motor 2 cannot be correctly controlled.

[0117] The output adjustment processing unit 56 stops the beat compensation in the speed range where a problem may occur in the operation of the beat suppression control unit 46, thereby eliminating the influence of the malfunction. That is, the beat component suppression operation is stopped based on the angular velocity ω calculated by the speed calculation unit 44.

[0118] exist Figure 5 In the output adjustment processing unit 56 , the angular velocity ω of the motor 2 subjected to absolute value processing is input, and the beat compensation voltages ΔVu**, ΔVv**, and ΔVw** output from the low-pass filter 54 are adjusted according to the angular velocity of the motor 2 .

[0119] Figure 6 This is a diagram for explaining the processing of the output adjustment processing unit 56 in the second embodiment.

[0120] exist Figure 6 In FIG. 5 , the vertical axis represents the output value of the output adjustment processing unit 56 , and the horizontal axis represents the angular velocity ω from the velocity calculation unit 44 input to the output adjustment processing unit 56 .

[0121] The motor 2 is moving at an angular velocity ω min1 To max1 When in operation, the beat suppression control unit 46 performs beat compensation. That is, the output value of the output adjustment processing unit 56 is 1, which is provided to the output adjustment multiplier 57, and the output from the low-pass filter 54 is multiplied by 1, thereby outputting the output from the low-pass filter 54 to the beat compensation amount subtraction unit 49.

[0122] At motor 2, the angular velocity ω min0(minimum speed (first angular velocity)) or less max0 In the case of an angular velocity greater than (maximum velocity (4th angular velocity)), the beat compensation is stopped. That is, the output value of the output adjustment processing unit 56 is 0, which is provided to the output adjustment multiplier 57, and the output from the low-pass filter 54 is multiplied by 0, so that the output from the low-pass filter 54 is not output to the beat compensation amount subtraction unit 49.

[0123] When the angular velocity exceeds ω min0 (1st angular velocity) and at ω min1 At a speed of less than (the second angular velocity), the output value of the output adjustment processing unit 56 increases from 0 to 1 at an arbitrary slope.

[0124] In addition, from the angular velocity ω max1 (3rd angular velocity) above to ω max0 At a speed of (the fourth angular velocity), the output value of the output adjustment processing unit 56 decreases from 1 to 0 at an arbitrary slope.

[0125] Thus, from the angular velocity ω min0 to min1 The angular velocity and the angular velocity ω max1 to max0 The beat compensation amount can be increased or decreased with an arbitrary gradient at the angular velocity.

[0126] As described above, according to the second embodiment of the present invention, similarly to the first embodiment, it is possible to realize a power conversion device that does not require adaptation work and can suppress current beats regardless of the operating state of the motor.

[0127] Furthermore, according to Example 2, the configuration is such that the beat compensation is stopped in the speed region where the speed of the motor 2 is below the minimum speed and above the maximum speed. Therefore, even when the speed of the motor 2 is low and the frequency of the assumed current beat component is close to the fundamental frequency of the phase current, or when the speed of the motor 2 is very high and the influence of the detection delay and calculation delay of the three-phase currents iu, iv, and iw becomes large, the output torque of the motor 2 can be correctly controlled.

[0128] In addition, it is configured so that at an angular velocity ω min0 to min1 The angular velocity and the angular velocity ω max1 to max0 At a speed of ω, the beat compensation amount is increased or decreased with an arbitrary slope, but it is also possible not to increase or decrease the beat compensation amount with an arbitrary slope, but to configure it so that at a speed of ω min1 When the output value of the output adjustment processing unit 56 is set to 1, the angular velocity ω max1 When the output value of the output adjustment processing unit 56 is set to 1 to 0, the output value of the output adjustment processing unit 56 is set to 1 to 0.min1 When the output value of the output adjustment processing unit 56 is set to 0.

[0129] Next, Example 3 of the present invention will be described.

[0130] Embodiment 3 is an example of an electric vehicle system including a power conversion device.

[0131] Figure 7 This is a schematic diagram of the configuration of an electric vehicle system according to a third embodiment of the present invention.

[0132] In addition, here, an example of an electric vehicle system equipped with the power conversion device of either the first embodiment or the second embodiment will be described.

[0133] like Figure 7 As shown, the electric vehicle system 58 has a pair of axles 59 and 60 axially supported on the vehicle body. Wheels 61 and 62 are fixed to both ends of one axle 59, and wheels 63 and 64 are fixed to both ends of the other axle 60. The motor 2 is connected to the axle 59, and the rotational power of the motor 2 is transmitted to the wheels 61 and 62 via the axle 59.

[0134] The motor drive device (motor control device) 65 receives the command torque T* generated by a higher-level system such as an ECU, and drives the motor 2. The motor drive device 65 includes the power conversion device of the first or second embodiment.

[0135] In the case where the present invention is applied to the electric vehicle system 58 , it is possible to avoid a problem in which the overcurrent protection is activated due to the current beat, thereby causing the inverter to stop.

[0136] Therefore, the operation quality of the electric vehicle system 58 can be improved, and the reliability can be improved.

[0137] Furthermore, according to the present invention, it is possible to suppress the deterioration of the motor efficiency due to the current pulsation phenomenon. As a result, it is possible to expect improvement in the power use efficiency in the electric vehicle system 58.

[0138] In the above embodiment, Figure 2 In the embodiment, the beat suppression control unit 46 and the beat compensation amount subtraction unit 49 are separately provided, but the beat suppression control unit 46 may be configured to include the beat compensation amount subtraction unit 49, and the three-phase voltage command values ​​from the two-phase to three-phase conversion unit 43 are output to the beat compensation amount subtraction unit 49. The configuration in which the beat suppression control unit 46 includes the beat compensation amount subtraction unit 49 is defined as a beat compensation unit.

[0139] In addition, in the above-mentioned embodiment, Figure 4In the embodiment, the motor inverse model unit 53 and the low-pass filter 54 are separately provided, but the motor inverse model unit 53 and the low-pass filter 54 may be integrated as one functional block. The motor inverse model unit 53 and the low-pass filter 54 are defined as a beat compensation voltage calculation unit as one functional block. The beat compensation voltage calculation unit estimates the voltage generated by the current beat component of the inverter 1.

[0140] In addition, the output adjustment processing unit 56 and the output adjustment multiplier 57 may be defined as one functional block. The output adjustment processing unit 56 and the output adjustment multiplier 57 may be defined as one functional block as an output adjustment unit.

[0141] In addition, the present invention is not limited to the above-described embodiment, and includes various modifications.

[0142] For example, the above-mentioned embodiments are examples described in detail in order to explain the present invention in an easily understandable manner, and are not necessarily limited to those having all the described configurations.

[0143] Furthermore, a part of the configuration of one embodiment may be replaced with the configuration of another embodiment, and the configuration of one embodiment may be added to the configuration of another embodiment.

[0144] In addition, for a part of the configuration of each embodiment, other configurations may be added, deleted, or replaced. An example is given below.

[0145] The switching element used for the inverter 1 is not limited to Si-IGBT. The switching element may be replaced from Si-IGBT to SiC-MOSFET.

[0146] The motor 2 is not limited to the IPMSM, and may be replaced by a surface magnet type synchronous motor or an induction motor, for example.

[0147] Furthermore, the DC voltage source of the inverter 1 is not limited to a battery. In a system connected to an AC power system, the AC power of the system can be rectified into DC by a rectifier to obtain a DC voltage source.

[0148] Explanation of symbols

[0149] 1…Inverter, 2…Motor, 3…Battery, 4…Controller, 5, 6, 7…Three-phase winding, 8…Magnetic pole position sensor, 9 (θ)…Magnetic pole position signal, 10…Current sensor, 11, 12, 13…Phase current sensor signal, 14 to 19…Switching element, 20 to 25…Flyback diode, 26 to 31…Gate drive signal, 32…Gate signal, 33…High potential DC wiring, 34…Low potential DC wiring, 35…Gate drive circuit, 36…Voltage sensor, 37…DC voltage sensor signal, 38…Smoothing capacitor, 39…Torque command, 40…Current command operation unit, 41…Three-phase Two-phase conversion unit, 42...current control unit, 43, 50...two-phase to three-phase conversion unit, 44...speed calculation unit, 45...PWM gate control signal generation unit (control signal generation unit), 46...beat suppression control unit, 47, 48...deviation calculator, 49...beat compensation amount subtraction unit, 51...magnetic pole position correction unit, 52...subtractor, 53...motor inverse model unit, 54...low-pass filter, 55...feedback loop, 56...output adjustment processing unit, 57...output adjustment multiplier, 58...electric vehicle system, 59, 60...axles, 61~64...wheels, 65...motor drive device (motor control device).

Claims

1. A power conversion device, characterized in that: have: an inverter, which converts DC voltage to AC voltage to drive an AC motor; a beat compensating unit for suppressing a current beat component of an output current of the inverter; A three-phase voltage command value generating unit that generates three-phase voltage command values; as well as a control signal generating unit for generating a drive signal for driving the inverter, The beat compensation unit comprises: a beat suppression control unit that outputs a beat compensation voltage, comprising: a beat extraction unit that calculates a beat component of an output current of the inverter; and a beat compensation voltage calculation unit that includes: a motor inverse model unit that calculates a disturbance estimation voltage based on the current beat component output from the beat extraction unit; and a low-pass filter that removes noise from the disturbance estimation voltage output from the motor inverse model unit, the beat compensation voltage calculation unit estimating the beat compensation voltage based on the beat component calculated by the beat extraction unit; and a beat compensation amount subtracting unit that subtracts the beat compensation voltage output by the beat suppression control unit from the three-phase voltage command value output by the three-phase voltage command value generating unit and outputs the result to the control signal generating unit, The power conversion device suppresses a current beat component of an output current of the inverter based on the beat compensation voltage estimated by the beat compensation voltage calculation unit.

2. The power conversion device according to claim 1, characterized in that: Also available: a speed calculation unit that calculates the angular speed of the motor; and An output adjustment unit stops the beat component suppression operation performed by the beat compensation unit based on the angular velocity calculated by the velocity calculation unit.

3. The power conversion device according to claim 2, characterized in that: The output adjustment unit stops the beat component suppression operation when the angular velocity is less than or equal to a first angular velocity or when the angular velocity is greater than or equal to a fourth angular velocity.

4. The power conversion device according to claim 3, characterized in that: When the angular velocity exceeds the first angular velocity and is lower than the second angular velocity, the output adjustment unit causes the beat component suppression action to increase incline from the first angular velocity to the second angular velocity. When the angular velocity exceeds the third angular velocity and is lower than the fourth angular velocity, the output adjustment unit causes the beat component suppression action to decrease incline from the third angular velocity to the fourth angular velocity.

5. An electric vehicle system, characterized in that: have: an electric motor that drives the vehicle; and a motor control device that controls the motor, The motor control device includes a power conversion device, The power conversion device comprises: an inverter, which converts DC voltage to AC voltage to drive an AC motor; a beat compensating unit for suppressing a current beat component of an output current of the inverter; A three-phase voltage command value generating unit that generates three-phase voltage command values; as well as a control signal generating unit for generating a drive signal for driving the inverter, The beat compensation unit comprises: a beat suppression control unit that outputs a beat compensation voltage, comprising: a beat extraction unit that calculates a beat component of an output current of the inverter; and a beat compensation voltage calculation unit that includes: a motor inverse model unit that calculates a disturbance estimation voltage based on the current beat component output from the beat extraction unit; and a low-pass filter that removes noise from the disturbance estimation voltage output from the motor inverse model unit, the beat compensation voltage calculation unit estimating the beat compensation voltage based on the beat component calculated by the beat extraction unit; and a beat compensation amount subtracting unit that subtracts the beat compensation voltage output by the beat suppression control unit from the three-phase voltage command value output by the three-phase voltage command value generating unit and outputs the result to the control signal generating unit, The power conversion device suppresses a current beat component of an output current of the inverter based on the beat compensation voltage estimated by the beat compensation voltage calculation unit.

6. The electric vehicle system according to claim 5, characterized in that: The power conversion device further comprises: a speed calculation unit that calculates the angular speed of the motor; and An output adjustment unit stops the beat component suppression operation performed by the beat compensation unit based on the angular velocity calculated by the velocity calculation unit.

7. The electric vehicle system according to claim 6, characterized in that: The output adjustment unit stops the beat component suppression operation when the angular velocity is less than or equal to a first angular velocity or when the angular velocity is greater than or equal to a fourth angular velocity.

8. The electric vehicle system according to claim 7, characterized in that: When the angular velocity exceeds the first angular velocity and is lower than the second angular velocity, the output adjustment unit causes the beat component suppression action to increase incline from the first angular velocity to the second angular velocity. When the angular velocity exceeds the third angular velocity and is lower than the fourth angular velocity, the output adjustment unit causes the beat component suppression action to decrease incline from the third angular velocity to the fourth angular velocity.

Images