Charge control device

Abstract

To suppress generation of torque during charging and prevent vibration, noise, and rotation of an electric motor in a charge control device using the electric motor and a power converter.SOLUTION: A charge control device 100 boosts the voltage of a charger 200 using an electric motor 400 and a power converter 600, and charges a battery 700. The charge control device 100 includes a charge current control unit 120, 130 that controls charge current for the battery 700 to become equal to a charge current command value in*, a dq-axis current control unit 150, 160 that controls a dq-axis current value of the electric motor 400 on the basis of dq-axis current command values id1*, iq1*, and a dq-axis current command value correction unit 180 that corrects the dq-axis current command values id1*, iq1*. The dq-axis current command value correction unit 180 corrects the dq-axis current command values id1*, iq1* so as to cancel torque generated in the electric motor 400 by the charge current on the basis of a charge current target value or a zero-sequence current i0* which is calculated from phase currents of the electric motor 400.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a charge control device. [Background technology]

[0002] Electric vehicles primarily use three-phase AC motors as their driving source. These motors are powered by converting DC power from a battery or other source into AC power using a power converter, which then supplies the power to the motor. When an electric vehicle is driven in this way, the remaining capacity of the battery decreases, so the battery must be connected to a charger and charged. Charging methods are broadly divided into normal charging and rapid charging. The former is connected to a household outlet and supplies AC power, while the latter is supplied with DC power from a rapid charger installed at a charging station or similar. In recent years, efforts have been made to increase the battery voltage of electric vehicles in order to improve their efficiency, and there are practical examples of vehicles with battery voltages of 800V. Meanwhile, the voltage on the quick charger side is often 400-500V DC. To charge a high-voltage battery with such quick charging equipment, a circuit that boosts the voltage on the quick charger side must be installed on the charger side or on the vehicle side. However, installing a boost circuit increases the size and cost of the system. Therefore, Patent Document 1 discloses a technology in which the neutral point of the electric motor is connected to the quick charger, and a boost chopper is formed using the windings of the electric motor and the switching elements of the power converter, thereby boosting the voltage of the quick charger and supplying power to the high-voltage battery. By using this technology, there is no need to provide an additional boost circuit, which prevents the system from becoming larger and the costs from increasing. However, charging technologies using such voltage boosting methods pass current through the motor, which generates torque, resulting in vibration, noise, and motor rotation during charging, and may cause deterioration of mechanical parts. Patent Document 2 discloses a technique for preventing the rotation of the electric motor by controlling the current (q-axis current) that contributes to the torque of the electric motor to zero during charging. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-175363 [Patent Document 2] Special Publication No. 2022-540573 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in a charging system that connects the neutral point of the motor to a charger and uses the motor windings and a power converter, the currents flowing through each phase winding of the motor become unbalanced (the sum of the currents of each phase is non-zero), and zero-phase current flows through the motor.

[0005] Therefore, even if the q-axis current of the motor is set to zero as in the technology described in Patent Document 2, torque due to the zero-phase current is generated, which may result in vibration, noise, and motor rotation during charging.

[0006] An object of the present invention is to suppress the generation of torque during charging in a charge control device using an electric motor and a power converter, thereby preventing vibration, noise, and electric motor rotation. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention is configured as follows.

[0008] A charge control device that uses an electric motor and a power converter to boost the voltage of an external charger and charge a battery includes: a charge current control unit that controls the charge current of the battery so that it coincides with a charge current command value; a dq-axis current control unit that controls a d-axis current value and a q-axis current value of the electric motor based on a d-axis current command value and a q-axis current command value; and a dq-axis current command value corrector that corrects the d-axis current command value and the q-axis current command value, based on a charge current target value or a zero-sequence current calculated from each phase current of the electric motor, so as to cancel out torque generated in the electric motor by the charge current. [Effects of the Invention]

[0009] According to the present invention, in a charge control device using an electric motor and a power converter, it is possible to suppress the generation of torque during charging, and to prevent vibration, noise, and rotation of the electric motor. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is an overall configuration diagram of a charging system according to a first embodiment of the present invention. [Figure 2] 1 is a block diagram showing main functions of a charge control device according to a first embodiment of the present invention. [Figure 3] FIG. 3 is a diagram illustrating main functions of a dq-axis current command value corrector according to the first embodiment of the present invention. [Figure 4] FIG. 10 is an explanatory diagram of the second embodiment of the present invention, and is a characteristic diagram of the d-axis current and the q-axis current when the torque generated in the electric motor is T0′. [Figure 5] FIG. 10 is a diagram illustrating operating points of dq-axis currents in the second and third embodiments of the present invention. [Figure 6] FIG. 10 is a diagram illustrating operating points of dq-axis currents in the fourth embodiment of the present invention. [Figure 7] FIG. 10 is an explanatory diagram of the operation of the fifth embodiment of the present invention. [Figure 8] FIG. 10 is an explanatory diagram of the operation of the sixth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The following description and drawings are examples for explaining the present invention, and some omissions and simplifications have been made as appropriate for clarity of explanation. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural. [Example]

[0012] Example 1 FIG. 1 is a diagram illustrating the overall configuration of a charging system 1 according to a first embodiment.

[0013] In FIG. 1, the charging system includes a charging control device 100, an external charger 200, an external voltage detector 300, an electric motor 400, a current detector 500, a power converter 600, a battery 700, a battery voltage detector 800, and a position detector 900.

[0014] The external charger 200 is a rapid charger that is installed in, for example, a charging station, and is a power supply source for charging the battery 700.

[0015] The external voltage detector 300 is a voltage sensor that detects the voltage of the external charger 200 .

[0016] The electric motor 400 is a permanent magnet synchronous motor configured with a three-phase Y connection in the first embodiment. The neutral point of the electric motor 400 is connected to the external charger 200.

[0017] The current detector 500 is disposed on the electrical wiring between the electric motor 400 and the power converter 600 and detects the current flowing through the electric motor 400 .

[0018] The power converter 600 is a three-phase inverter and is made up of six semiconductor elements. When driving an electric vehicle, the power converter 600 converts DC power from the battery 700 into AC power and drives the electric motor 400.

[0019] The battery 700 is a power storage device provided in the electric vehicle. The battery 700 is a secondary battery that can be repeatedly charged, such as a lithium ion battery, a lead storage battery, a nickel-metal hydride battery, a nickel-cadmium battery, or an all-solid-state battery.

[0020] The battery voltage detector 800 detects the voltage of the battery 700 .

[0021] The position detector 900 is a sensor, such as a resolver, that detects the rotation angle of the electric motor 400. If the electric motor 400 is a permanent magnet type synchronous motor, the position detector 900 detects the position of the north pole of the permanent magnet.

[0022] The charging control device 100 receives as input signals the voltage Vin of the external charger 200 detected by the external voltage detector 300, the currents iu, iv, iw of each phase detected by the current detector 500, the voltage Vbatt of the battery 700 detected by the battery voltage detector 800, and the rotation angle θ of the electric motor 400 detected by the position detector 900, and sends switching signals Su, Sv, Sw to the switching elements of the power converter 600 so as to boost the voltage Vin to the voltage Vbatt of the battery 700 and supply the DC power of the external charger 200 to the battery 700.

[0023] In charging system 1, external charger 200 and the neutral point of electric motor 400 are connected, electric motor 400 is connected to power converter 600, and power converter 600 is connected to battery 700. The windings that make up electric motor 400 have inductance, and this is used to control the on / off of the switching elements of power converter 600 to operate as a boost chopper, thereby boosting the voltage of external charger 200 to battery voltage 700 for charging.

[0024] When the battery 700 is charged by the charging system 1 , a charging current in flows from the external charger 200 to the neutral point of the electric motor 400 .

[0025] The current in that flows during charging and the phase currents iu, iv, and iw have the following relationship (1):

[0026] in=iu+iv+iw (1) That is, during charging, a three-phase unbalanced state occurs in which the sum of the currents of each phase is non-zero. Normally, when driving the electric motor 400 configured with a Y connection as in the first embodiment, the sum of the currents of each phase is always zero, but when the charging system 1 is operated, a current state different from that in normal driving occurs.

[0027] Generally, the voltage equation for a permanent magnet synchronous motor is expressed using a coordinate system in which the direction of the magnetic flux of the magnet is the d-axis and the axis electrically 90 degrees ahead of the d-axis is the q-axis, with the sum of the currents of each phase being zero.

[0028] However, as described above, in charging system 1, the sum of the currents of the phases is non-zero, and therefore the voltage equation of electric motor 400 takes a form different from that when an electric vehicle is normally driven.

[0029] When the sum of the currents of each phase is non-zero, the voltage equations of the permanent magnet motor are expressed as the following equations (2) to (4). However, since the speed of the motor 400 can be approximated to zero when the charging system 1 is operating, the speed electromotive force and armature reaction are omitted.

[0030] vd = R × id + p(Ld × id) (2) vq=R×iq+p(Lq×iq) (3) v0=R×i0+p(L0×i0) (4) where vd is the d-axis voltage, vq is the q-axis voltage, v0 is the zero-phase voltage, R is the winding resistance, Ld is the d-axis inductance, Lq is the q-axis inductance, L0 is the zero-phase inductance, id is the d-axis current, iq is the q-axis current, i0 is the zero-phase current, and p is the time differential operator.

[0031] The d-axis and q-axis voltages and currents can be calculated by the commonly known coordinate transformation of the three-phase AC voltages and currents. On the other hand, the zero-phase voltages and currents are related to the three-phase AC voltages and currents by the following equations (5) and (6).

[0032] v0=(vu+vv+vw) / √(3) ···(5) i0=(iu+iv+iw) / √(3) ···(6) However, the coordinate transformation is described as an absolute transformation in which the power before and after the transformation remains unchanged. It may be rewritten as a relative transformation in which the power before and after the transformation changes.

[0033] As described above, when a Y-connected three-phase AC motor is normally driven, the sum of the voltages and currents of each phase is zero, so equations (5) and (6) are also zero. Therefore, equation (4) is also zero during normal driving.

[0034] However, when the charging system 1 is operated, the equations (5) and (6) do not become zero, and therefore the zero-phase voltage and current expressed by the equation (4) occur.

[0035] Taking into consideration the zero-phase voltage and current, the torque of the electric motor 400 is expressed by the following equation (7).

[0036] T=Pp×{(Ld-Lq)×id×iq+Φm×iq+Φ0×sin(θ-δ)×i0} ···(7) where T is the torque, Pp is the number of pole pairs, Φm is the interlinkage magnetic flux due to the permanent magnet, Φ0 is the third component of the permanent magnet magnetic flux, θ is the electrical rotation angle of the motor (the value detected by the position detector 900), and δ is the phase difference between θ and Φ0.

[0037] As shown in equation (7), torque due to the zero-phase current is generated in the electric motor 400. That is, the zero-phase current shown in equation (6) is obtained by dividing equation (1) of the charging current in by √(3), and therefore torque due to the zero-phase current is generated by charging by the charging system 1.

[0038] Therefore, even if the q-axis current is controlled to zero, the electric motor 400 generates torque, which may cause vibration and noise in the charging system 1 and rotation of the electric motor 400.

[0039] Next, a method for suppressing the torque caused by the charging current in (or the zero-phase current i0) will be described with reference to FIG.

[0040] The charging control device 100 in the first embodiment includes a charging current command generator 110, a zero-phase-sequence current command generator 120, a zero-phase-sequence current controller 130, a first coordinate conversion unit 140, a d-axis current controller 150, a q-axis current controller 160, a second coordinate conversion unit 170, and a dq-axis current command value corrector 180.

[0041] The zero-phase-sequence current command generator 120 and the zero-phase-sequence current controller 130 form a charging current controller. The d-axis current controller 150 and the q-axis current controller 160 form a dq-axis current controller. The charging current command generator 110 receives as input signals the voltage Vin of the external charger 200 detected by the external voltage detector 300 and the voltage Vbatt of the battery 700 detected by the battery voltage detector 800. Then, the charging current command generator 110 calculates a charging current command value in* by performing tracking control using a commonly known proportional-integral control or the like so as to boost the voltage Vin to the voltage Vbatt, and transmits the calculated charging current command value in* to the zero-phase current command generator 120.

[0042] The zero-phase current command generator 120 receives the charging current command value in* as an input signal and converts it into a zero-phase current. This conversion is performed, for example, based on the relationship between equations (1) and (6). The zero-phase current command i0*, which is an output signal of the zero-phase current command generator 120, is transmitted as an input signal to the zero-phase current controller 130 and the dq-axis current command value corrector 180.

[0043] The zero-phase current controller 130 controls the zero-phase current detection value i0, which is the detected value of the zero-phase current, using proportional-integral control or the like so that it coincides with its target value, the zero-phase current command i0*, and transmits its output to the second coordinate transformation unit 170 as the zero-phase voltage command v0*.

[0044] The first coordinate conversion unit 140 receives as input signals the currents iu, iv, and iw of each phase detected by the current detector 500 and the rotation angle θ of the electric motor 400 detected by the position detector 900, and converts the currents iu, iv, and iw of each phase into a d-axis current id, a q-axis current iq, and a zero-phase current i0 based on the rotation angle θ. The converted d-axis current id, q-axis current iq, and zero-phase current i0 are sent as input signals to the d-axis current control unit 150, the q-axis current control unit 160, and the zero-phase current controller 130, respectively.

[0045] The d-axis current control unit 150 receives as input signals the d-axis current command value id* and the d-axis current id output by a dq-axis current command value correction unit 180 (described later). Then, it performs control using proportional-integral control or the like so that the d-axis current id coincides with the d-axis current command value id*, and transmits the result as a d-axis voltage command vd* to the second coordinate conversion unit 170.

[0046] The q-axis current control unit 160 receives, as input signals, a q-axis current command value iq* output by a dq-axis current command value correction unit 180 (described later) and the q-axis current iq output by the first coordinate conversion unit 140. Then, the q-axis current control unit 160 performs control using proportional-integral control or the like so that the q-axis current iq coincides with the q-axis current command value iq*, and transmits it to the second coordinate conversion unit 170 as a q-axis voltage command vq*.

[0047] The second coordinate conversion unit 170 receives the d-axis voltage command vd*, the q-axis voltage command vq*, the zero-phase voltage command v0*, and the rotation angle θ, and converts the d-axis voltage command vd*, the q-axis voltage command vq*, and the zero-phase voltage command v0* into three-phase AC. After converting into three-phase AC, the second coordinate conversion unit 170 performs a commonly known pulse width modulation or the like to generate switching signals Su, Sv, and Sw that control the on / off of switching elements of the power converter 600, and transmits the switching signals to the power converter 600.

[0048] The dq-axis current command value corrector 180 receives, as input signals, a first d-axis current command value id1*, a first q-axis current command value iq1*, a rotation angle θ, and a zero-phase current command i0*. In the first embodiment, the first d-axis current command value id1* and the first q-axis current command value iq1* are, for example, zero. The dq-axis current command value corrector 180 receives these input signals, corrects the first d-axis current command value id1* and the first q-axis current command value iq1* based on the zero-phase current command i0* and the rotation angle θ, and transmits the corrected values ​​as the d-axis current command value id* and the q-axis current command value iq* to the d-axis current control unit 150 and the q-axis current control unit 160, respectively.

[0049] As described above, the flow of the zero-phase current causes the electric motor 400 to generate torque. Therefore, the dq-axis current command value corrector 180 corrects the first d-axis current command value id1* and the first q-axis current command value iq1* so as to cancel out the torque generated by the zero-phase current.

[0050] The dq-axis current command value corrector 180 will be described in detail with reference to FIG.

[0051] 3, a dq-axis current command value corrector 180 in the first embodiment includes a phase difference calculator 181, a sine function 182, a magnet flux multiplier 183, a zero-phase-sequence current torque calculator 184, a zero-phase-sequence current torque / current converter 185, and a correction reflector 186.

[0052] The dq-axis current command value corrector 180 calculates the torque generated by the zero-phase current expressed by the following equation (8).

[0053] T0=Pp×Φ0×sin(θ-δ)×i0 (8) The phase difference calculation unit 181 calculates the phase difference δ between the rotation angle θ and the phase difference δ of the third-order component Φ 0 of the permanent magnet magnetic flux, and sends the result to the sine function 182 .

[0054] The sine function 182 receives the result of the phase difference calculation unit 181 as an input signal, calculates sin(θ−δ), and sends the result to the zero-phase current torque calculation unit 184 .

[0055] The magnet flux multiplication unit 183 receives the zero-phase current command i0* as an input signal, calculates the product Φ0×Pp×i0* of the zero-phase current command i0*, the third-order component Φ0 of the magnet flux, and the number of pole pairs Pp of the motor 400, and transmits the result to the zero-phase current torque calculation unit 184.

[0056] The zero-phase current torque calculation unit 184 calculates the product of sin(θ-δ), which is the output signal of the sine function 182, and Φ0×Pp×i0*, which is the output signal of the magnet flux multiplication unit 183, and outputs the result of equation (8) to calculate the torque T0 generated by the zero-phase current and transmits it to the zero-phase current torque / current conversion unit 185.

[0057] The zero-phase current torque / current converter 185 converts the torque T0 into a d-axis current correction value idcmp and a q-axis current correction value iqcmp so that the dq-axis current generates a torque equal in magnitude to but opposite in sign to the torque T0 due to the zero-phase current. For example, when the conversion is performed assuming the d-axis current correction value to be zero, the q-axis current correction value iqcmp is calculated using the following equation (9).

[0058] iqcmp=-T0 / (Pp×Φm) (9) Since there are an infinite number of combinations of the d-axis current correction value idcmp and the q-axis current correction value iqcmp that generate a torque with an opposite sign to the torque T0, various forms other than equation (9) can be used.

[0059] The d-axis current correction value idcmp and the q-axis current correction value iqcmp calculated by the zero-phase current torque / current conversion unit 185 are transmitted to the correction reflection unit 186 .

[0060] The correction reflection unit 186 receives as input the first d-axis current command value id1* and the first q-axis current command value iq1*, and the dq-axis current correction values ​​idcmp and iqcmp, and performs an addition operation on the values ​​of each axis to correct the first d-axis current command value id1* and the first q-axis current command value iq1*, and outputs them as the d-axis current command value id* and the q-axis current command value iq*.

[0061] As described above, the d-axis current control unit 150 and the q-axis current control unit 160 operate so that the corrected d-axis current command value id* and q-axis current command value iq* match the d-axis current id and i-axis current iq, and therefore, current flows through the electric motor 400 so that the torque T caused by the zero-phase current, which is the result of the above equation (7), becomes zero.

[0062] As a result, even when the charging system 1 is operated, the electric motor 400 does not generate torque, so vibrations, noise, and rotation of the electric motor 400 during charging can be prevented.

[0063] In the first embodiment of the present invention, a dq-axis current control unit (d-axis current control unit 150, i-axis current controller 160) is provided to control the dq-axis current of the electric motor 400 so that the dq-axis current of the electric motor 400 coincides with the dq-axis current command value, which is the target value, and the dq-axis current control unit is configured as a charging control device 100 that controls the dq-axis current based on the charging current target value or the charging current so as to cancel out the torque generated by the charging current of the electric motor 400.

[0064] Therefore, according to the first embodiment of the present invention, in a charging system in which the electric motor 400 and the power converter 600 operate as a boost chopper, the generation of torque by the electric motor 400 during charging is suppressed, thereby preventing vibration and noise in the charging system and rotation of the electric motor, thereby making it possible to reduce vibration and noise.

[0065] The charge control device 100 in the first embodiment of the present invention is configured to obtain the charge current command value in* by controlling the voltage Vin of the external charger 200 to follow the voltage Vbatt of the battery 700, but it is not necessarily required to calculate the charge current command value in*.

[0066] For example, the zero-phase voltage command v0* of the power converter 600 can be determined from the ratio between the voltage Vin of the external charger 200 and the voltage Vbatt of the battery 700, so the zero-phase voltage command v0* may be calculated directly without first calculating the charging current command value in* or the zero-phase current command i0*.

[0067] In this case, the number of required blocks is reduced, thereby simplifying the calculations. Furthermore, when this configuration is adopted, the dq-axis current command value corrector 180 only needs to calculate the d-axis current command value id* and the q-axis current command value iq* based on the zero-phase current i0 calculated from the actual phase currents of the electric motor 400, rather than the zero-phase current command i0*. By using the actual phase currents, the torque T0 due to the zero-phase current can be calculated more accurately. If noise in the actual zero-phase current i0 is a problem, the noise component may be removed using a low-pass filter or the like.

[0068] In the first embodiment of the present invention, the first d-axis current command value id1* and the first q-axis current command value iq1* are corrected based on the zero-phase current command i0* and the rotation angle θ, but as described above, the zero-phase current command i0* can be replaced with the actual zero-phase current i0.

[0069] Furthermore, since the zero-phase current command i0* and the charging current command value in* represent the same physical quantity but differ only in magnitude, the charging current command value in* and the charging current in may be calculated, and the first d-axis current command value id1* and the first q-axis current command value iq1* may be corrected based on the results.

[0070] When using command values ​​such as the zero-phase current command i0* or the charging current command value in*, the torque T0 generated by the zero-phase current is more resistant to noise when it is calculated. However, since there is a deviation from the actual current, the actual zero-phase current i0 or the actual charging current in can be used to prevent this.

[0071] In the first embodiment of the present invention, the zero-phase current controller 130, the d-axis current controller 150, and the q-axis current controller 160 are each shown as examples of proportional-integral control. However, the control does not necessarily have to be proportional-integral control, and various other forms can be used, such as feedforward compensation for the purpose of improving the response of boost and charge control.

[0072] Furthermore, the second coordinate conversion unit 170 in the first embodiment of the present invention performs coordinate conversion on the d-axis voltage command vd*, the q-axis voltage command vq*, and the zero-phase voltage command v0* based on the rotation angle θ to calculate the switching signals Su, Sv, and Sw that control the on / off of the switching elements of the power converter 600. However, the second coordinate conversion unit 170 may be configured to perform dead time compensation in accordance with the current value of each phase so as to correct the period (dead time) for preventing a short circuit in the power converter 600. This reduces the error between the actual output voltage of the power converter 600 and the voltage command, thereby enabling more accurate control.

[0073] Furthermore, the magnet flux multiplication unit 183 in the dq-axis current correction unit 180 of the first embodiment of the present invention is configured such that the third-order component Φ0 of the magnet magnetic flux is a fixed value, but if the third-order component Φ0 is dependent on the d-axis current id, the q-axis current iq, the zero-phase current i0, etc., then the characteristics may be obtained by a prior electromagnetic field analysis or the like and stored in a table, etc. This allows the torque T0 generated by the zero-phase current to be calculated with higher accuracy, thereby further reducing the generation of vibration and noise during charging.

[0074] Furthermore, in the first embodiment of the present invention, the rotation angle θ is obtained by the position detector 900. However, the rotation angle may be estimated from information on the voltage and current without providing the position detector 900, and the estimated result may be used as the rotation angle θ. This eliminates the need for the position detector 900, thereby reducing the cost of the system.

[0075] Example 2 Next, a description will be given of Example 2. If the d-axis current id and the q-axis current iq that cancel out the torque T0 generated by the zero-phase current are passed as in Example 1, these currents do not contribute to charging, which may lead to a deterioration in system efficiency.

[0076] The second embodiment relates to a configuration that minimizes the deterioration of efficiency.

[0077] 3, the case where the torque T0 output from the zero-phase current torque calculation unit 184 is −T0′ will be described as an example. For simplicity of explanation, the first d-axis current command value id1* and the first q-axis current command value iq1* will be described as zero.

[0078] Fig. 4 shows a characteristic diagram of the d-axis current and q-axis current when the torque generated in the electric motor 400 is T0'. Since the output of the zero-phase current torque calculation unit 184 is T0 = -T0', the d-axis current and q-axis current can be selected from the combinations on the characteristic diagram shown in Fig. 4. However, as mentioned above, the d-axis current and q-axis current do not contribute to charging, and this may result in a deterioration in efficiency.

[0079] Therefore, in the dq-axis current command value corrector 180 of the second embodiment, the point o that is the smallest distance from the origin on the characteristic diagram of Fig. 4 is selected as the d-axis current command corrected value idcmp and the q-axis current command corrected value iqcmp so as to minimize the d-axis current and the q-axis current. In other words, the point o is the point where the square root of the sum of the squares of the d-axis current and the q-axis current is smallest.

[0080] This minimizes the current, thereby preventing a deterioration in system efficiency while suppressing the torque due to the zero-phase current. For the sake of simplicity, the first d-axis current command value id1* and the first q-axis current command value iq1* have been described as being zero, but if they are not zero, the torque due to the first d-axis current command value id1* and the first q-axis current command value iq1* and the torque due to the zero-phase current can be calculated, and the zero-phase current / current converter 185 can be operated to cancel out the difference.

[0081] That is, the motor should be operated so that the d-axis current command value id* and the q-axis current command value iq* are minimized.

[0082] As described above, in the second embodiment of the present invention, when the torque due to the zero-phase current is canceled by generating torque using the d-axis current and the q-axis current, the d-axis and q-axis current command value correction values ​​idcmp and iqcmp are selected so that the square root of the sum of the squares of the d-axis current command value and the q-axis current command value becomes minimum.

[0083] As a result, in the second embodiment of the present invention, it is possible to suppress the generation of torque by the electric motor 400 during charging, minimize the generation of loss and the deterioration of efficiency, and shorten the charging time.

[0084] Example 3 Next, a third embodiment of the present invention will be described.

[0085] During charging of the battery 700, a pulse-width modulated voltage output by the power converter 600 is applied to the electric motor 400, causing a current ripple. This current ripple generates torque, which may result in vibration and noise during charging, such as contact noise between the electric motor 400 and mechanical parts connected thereto.

[0086] The third embodiment relates to a configuration for suppressing vibration and noise during charging.

[0087] FIG. 5 is a diagram showing an operating point o3 of the dq-axis currents in the second and third embodiments.

[0088] In the second embodiment, the dq-axis currents are controlled at point o where the distance from the origin of the characteristic diagram shown in FIG. 4 is minimum.

[0089] However, as mentioned above, current ripple occurs, and the current operating point changes by the amount of the q-axis current ripple, centered around operating point o, as shown in Figure 5. For this reason, the torque generated by the dq-axis current changes from torque T1 to torque T2, centered around torque T0 in Figure 5. If the difference between torque T1 and torque T2 is large, this results in a large torque ripple, which leads to vibration and noise during charging.

[0090] Therefore, the dq-axis current command value corrector 180 of the third embodiment operates at point o3 indicated by a square in Fig. 5. In other words, the dq-axis current command corrector 180 corrects the d-axis current value and the q-axis current value so that the d-axis current value of the electric motor 400 becomes positive.

[0091] The magnitude of the q-axis current ripple is determined by the characteristics of the electric motor 400 and the switching method of the power converter 600, so the magnitude of the q-axis current ripple is the same as in the second embodiment. However, the torque fluctuation range is from T0 to T3, and the magnitude of the torque ripple is smaller. This makes it possible to reduce vibration and noise during charging compared to operation in the second embodiment.

[0092] Although the charging time of Example 3 is longer than that of Example 2, by using Example 3 when there is ample charging time, such as charging at night, it is possible to obtain the same effect as Example 1 and also reduce noise.

[0093] Example 4 Next, a fourth embodiment of the present invention will be described.

[0094] Although the third embodiment can reduce vibration noise during charging of the battery 700, as shown by the square operating point o3 and the q-axis current ripple width in FIG. 5, if the torque ripple alternates between positive and negative values, the electric motor 400 will operate by the amount of backlash in mechanical parts such as gears connected to the electric motor 400, which may cause gear rattle noise.

[0095] Therefore, the dq-axis current command value corrector 180 in the fourth embodiment controls the dq-axis current at an operating point o4 indicated by a triangle in Fig. 6. At this operating point o4, the sign of the torque, including the torque due to the current ripple, is always in one direction (always positive torque in Fig. 6).

[0096] In other words, the dq-axis current command value correction unit 180 corrects the sign of the total torque of the torque due to the zero-phase current value of the electric motor 400, the torque due to the d-axis current value of the electric motor 400, and the torque due to the q-axis current value so that it is either positive or negative.

[0097] Since the sign of the torque is always unidirectional, even if there is backlash, the torque acting on the electric motor 400 always operates in only one direction, preventing continuous gear rattle and further suppressing noise.

[0098] According to the fourth embodiment, it is possible to obtain the same effects as those of the first embodiment, and also to reduce noise caused by backlash of mechanical parts.

[0099] Although FIG. 6 shows an example in which the d-axis current is positive, if the sign of the torque is always in one direction, the d-axis current may be made negative so as to simultaneously suppress loss.

[0100] Example 5 Next, a fifth embodiment of the present invention will be described.

[0101] If a d-axis current flows while the battery 700 is being charged, the d-axis current also contains a ripple component, which causes loss in the magnet (such as eddy current loss in the magnet) in the motor 400. If this condition continues, the magnet temperature will rise, which could cause thermal demagnetization.

[0102] Therefore, in the fifth embodiment, the d-axis current command value id* is changed in the dq-axis current command value unit 180 in accordance with the magnet temperature as shown in FIG.

[0103] Fig. 7 is a diagram showing the state in which charging starts at time ti1 and the d-axis current is flowing using the method described in Examples 1 to 4. In Fig. 7(a), as the charging time elapses, the magnet temperature rises due to losses occurring in the magnet.

[0104] 7(b), in the fifth embodiment, when the magnet temperature reaches a predetermined value Te (at time ti2), the dq-axis current command value corrector 180 sets the target value of the d-axis current to zero and corrects the d-axis current command value id1* in order to protect the magnet. This makes it possible to suppress magnet loss, prevent a rise in the magnet temperature, and protect the magnet from thermal demagnetization.

[0105] The magnet temperature can be detected in various ways, such as a method based on an estimated magnet flux value of the electric motor 400 or a method of calculation using a thermal equivalent circuit. The temperature of the electric motor 400 can be detected as the magnet temperature, and when the temperature of the electric motor 400 reaches a predetermined temperature, the target value of the d-axis current can be set to zero and the d-axis current command id1* can be corrected. The temperature of the electric motor 400 can also be detected in various ways, such as a method based on an estimated magnet flux value of the electric motor 400 or a method of calculation using a thermal equivalent circuit.

[0106] Furthermore, if the torque operating point changes due to the d-axis current being set to zero, the operating point of the q-axis current can be changed to control the output torque to be constant, as shown in Figure 7(c), thereby simultaneously preventing the rotation of the motor 400 and preventing vibration and noise.

[0107] Example 6 Next, a sixth embodiment of the present invention will be described.

[0108] When charging the vehicle battery 700, charging may be performed in a state where the ambient temperature is low. In this case, the temperature of the battery 700 is also low, which may result in a decrease in battery performance, such as a drop in the voltage of the battery 700.

[0109] Therefore, in the sixth embodiment, when the temperature of the battery 700 is detected to be a low temperature state, that is, below a predetermined temperature, the dq-axis current command value correction unit 180 superimposes harmonic components on the d-axis current command value id* and the q-axis current command value iq* to raise the temperature of the battery 700.

[0110] FIG. 8 shows an example when charging is started from a low battery temperature state. If a low battery temperature state is detected at the start of charging, harmonic components such as those shown in (b) and (c) of FIG. 8 are superimposed on the d-axis current command value id* and the q-axis current command value iq*, and the temperature rise operation (temperature rise mode) of the battery 700 is performed. When the battery temperature reaches a predetermined temperature Teb, the harmonic components of the d-axis current command value id* and the q-axis current command value iq* are returned to zero, and the system transitions to normal operation.

[0111] The sixth embodiment can obtain the same effects as the first embodiment, and can also prevent the battery 700 from becoming in a low temperature state, thereby preventing the performance of the battery 700 from deteriorating.

[0112] In addition, the operation of superimposing harmonic components and stopping the superimposition of high-frequency components on the d-axis current specification value id* and the q-axis current command value id* depending on the battery temperature can be performed by the zero-phase current / current conversion unit 185 of the dq-axis current command value correction unit 180.

[0113] The temperature of the battery 700 can be detected in various ways, such as by calculation using a thermal equivalent circuit. Furthermore, it can be estimated that the battery temperature has reached a predetermined temperature Teb based on the elapsed time since the start of charging.

[0114] Furthermore, in the above explanation, the case is where the temperature of the battery 700 is detected to be a low temperature state where it is below a predetermined temperature, but if the electric motor 400 is detected to be a low temperature state where it is below a predetermined temperature, it is also possible to configure the d-axis current specification value id* and the q-axis current iq* to be superimposed with harmonic components for raising the temperature of the electric motor 400.

[0115] Furthermore, when it is detected that either the battery 700 or the electric motor 400 is in a low-temperature state where the temperature is below a predetermined temperature, it is possible to configure the d-axis current command value id* and the q-axis current command value iq* to be superimposed with harmonic components for raising the temperature of the electric motor 400.

[0116] As described above, according to the present invention, in a charge control device using an electric motor and a power converter, it is possible to suppress the generation of torque during charging, and to prevent vibration, noise, and rotation of the electric motor. [Explanation of symbols]

[0117] 1···Charging system, 100···Charging control device, 110···Charging current command generator, 120···Zero-phase current command generator, 130···Zero-phase current controller, 140···First coordinate transformation unit, 150···d-axis current control unit, 160···q-axis current control unit, 170···Second coordinate transformation unit, 180···dq-axis current command value correction unit, 181···Phase difference calculation unit, 182···Sine function, 183· ··Magnetic flux multiplication unit, 184··Zero-phase current torque calculation unit, 185··Zero-phase current / current conversion unit, 186··Correction reflection unit, 200··External charger, 300··External voltage detector, 400··Electric motor, 500··Current detector, 600··Power converter, 700··Battery, 800··Battery voltage detector, 900··Position detector, T0··Torque generated by zero-phase current

Claims

1. A charging control device that uses an electric motor and a power converter to boost the voltage of an external charger and charge a battery, a charging current control unit that controls the charging current of the battery so that the charging current coincides with a charging current command value; a dq-axis current control unit that controls a d-axis current value and a q-axis current value of the electric motor based on a d-axis current command value and a q-axis current command value; a dq-axis current command value correcting unit that corrects the d-axis current command value and the q-axis current command value; Equipped with the dq-axis current command value correction unit corrects the d-axis current command value and the q-axis current command value based on a charging current target value or a zero-phase current calculated from each phase current of the electric motor so as to cancel out torque generated in the electric motor by the charging current.

2. 2. The charge control device according to claim 1, The dq axis current command value correction unit A charge control device comprising: correcting the d-axis current command value and the q-axis current command value so that the sum of squares of the d-axis current value and the q-axis current value is minimized.

3. 2. The charge control device according to claim 1, The dq axis current command value correction unit A charge control device comprising: a charging control circuit for correcting the d-axis current value and the q-axis current value so that the d-axis current value is positive.

4. 2. The charge control device according to claim 1, The dq axis current command value correction unit a charge control device that corrects the d-axis current command value and the q-axis current command value so that the sign of a total torque of a torque due to a zero-phase current value of the motor, a torque due to the d-axis current value, and a torque due to the q-axis current value is either positive or negative.

5. 2. The charge control device according to claim 1, The dq axis current command value correction unit When the temperature of the electric motor reaches a predetermined value, A charging control device comprising: a controller for correcting the d-axis current command value so that the d-axis current value becomes zero;

6. 2. The charge control device according to claim 1, The dq axis current command value correction unit A charge control device comprising: a charging control unit that, when the temperature of the electric motor or the temperature of the battery is equal to or lower than a predetermined temperature, superimposes harmonic components on the d-axis current command value and the q-axis current command value.

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