Charging control method and charging control device

Abstract

To provide a charging control method and a charging control device capable of efficiently charging an inverter for driving a motor having a plurality of phases even if individual difference exists in a switching element included in the inverter when the inverter is used as a power factor improving circuit for charging.SOLUTION: When a battery 1 is charged by an external power source 5, synchronization control is performed for synchronizing an operation timing of turning on and / or off a plurality of switching elements Tr1 to Tr6. Then, at a timing when the plurality of switching elements Tr1 to Tr6 are turned on or off, phase currents iu, iv, iw that are a current flowing in respective phases of a motor 1 are detected, and an operation timing of one or more switching elements iu, iv, iw among the plurality of switching elements Tr1 to Tr6 is corrected based on the detected phase currents iu, iv, iw of each phase.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to a charge control method and a charge control device for charging a battery that drives a motor having multiple phases, using an inverter for driving the motor. [Background technology]

[0002] Patent Document 1 discloses a charging control method and a charging control device for synchronously operating multiple switching elements provided in an inverter for driving a motor when these switching elements are also used as switching elements for charging AC power. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-058178 A Summary of the Invention [Problem to be solved by the invention]

[0004] Each of the multiple switching elements included in the inverter has its own response time characteristic in response to an input of a switching command until the switching elements actually switch on and / or off. In other words, the response characteristics of the switching elements vary.

[0005] Furthermore, when the operation of a plurality of switching elements is synchronized in order to use an inverter for driving a motor as a power factor correction circuit for charging, if there are individual differences in the switching elements, charging efficiency deteriorates.

[0006] Specifically, if there is a delay in switching in some switching elements, the current will concentrate in a specific phase of a three-phase motor, for example, depending on the delay. The current concentrating in this specific phase is a current that circulates between phases and does not contribute to charging. For this reason, if there is an individual difference in the switching elements, the charging efficiency will deteriorate.

[0007] The present invention aims to provide a charging control method and a charging control device that can charge efficiently even if there are individual differences in the switching elements of an inverter for driving a motor having multiple phases when the inverter is used as a power factor correction circuit for charging. [Means for solving the problem]

[0008] A charge control method according to an embodiment of the present invention is implemented in a motor control system that drives a motor having multiple phases with power supplied from a battery via an inverter having multiple switching elements, and connects an external power source to the battery via the inverter when charging the battery from the external power source. The charge control method also performs synchronous control to synchronize the operation timings of turning on and / or off the multiple switching elements when charging the battery from the external power source. Then, phase currents, which are currents flowing through each phase of the motor, are detected at the timing when a circulating current circulating between the phases occurs, and the operation timings of one or more switching elements among the multiple switching elements are corrected based on the detected phase currents of each phase. Effect of the Invention

[0009] According to the present invention, when an inverter for driving a motor having multiple phases is used as a power factor correction circuit for charging, efficient charging can be achieved even if there are individual differences in the switching elements of the inverter. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram showing the configuration of a motor control system. [Diagram 2] FIG. 2 is an explanatory diagram showing the relationship between the operation mode, the on / off state of the relay, and the switching frequency. [Diagram 3] FIG. 3 is a graph showing static characteristics of a switching element. [Figure 4]FIG. 4 is a timing chart showing the basic transition of phase voltages and line voltages during (A) motor driving and (B) charging operation. [Diagram 5] FIG. 5 is a timing chart showing the operation timing of the switching elements, the phase voltages, and the phase currents during a charging operation when there is no individual difference between the switching elements. [Figure 6] FIG. 6 is a timing chart showing the operation timing of the switching elements, the phase voltages, and the phase currents during a charging operation when there are individual differences in the switching elements. [Figure 7] FIG. 7 is an explanatory diagram showing the state of operation during a dead time period when a specific switching element (A) has no delay in turning off and (B) has a delay in turning off. [Figure 8] FIG. 8 is a flow chart illustrating the operation of the charging mode of operation. [Figure 9] FIG. 9 is a block diagram showing a modified example of the circuit configuration of the motor control system. [Figure 10] FIG. 10 is a block diagram showing a modified example of the circuit configuration of the motor control system. [Figure 11] FIG. 11 is a block diagram showing a modified example of the circuit configuration of the motor control system. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0012] [First embodiment] Fig. 1 is a block diagram showing the configuration of a motor control system 100. As shown in Fig. 1, the motor control system 100 includes a battery 1, an inverter 2 (inverter device), a motor 3, a vehicle controller 4, and the like.

[0013] That is, the motor control system 100 is a system that uses a battery 1 as a power source and drives a motor 3 via an inverter 2. The motor control system 100 is mounted on, for example, an electric vehicle (EV) or a plug-in hybrid vehicle (PHEV). For this reason, the motor control system 100 drives the motor 3 based on a control signal input from a vehicle controller 4, which is a control device for the vehicle (hereinafter simply referred to as the vehicle) in which the motor control system 100 is mounted.

[0014] The battery 1 supplies power to drive the motor 3. In this embodiment, the battery 1 is a so-called high-voltage battery for vehicle use and is rechargeable. The battery 1 is also a DC power source and supplies DC power to the inverter 2. The motor 3 is driven by the power supplied by the battery 1.

[0015] When driving the motor 3, the inverter 2 converts the DC power output by the battery 1 into AC power and supplies the AC power to the motor 3. The configuration of the inverter 2 will be described in detail later.

[0016] The motor 3 is an electric motor (EM) having multiple phases. In this embodiment, the motor 3 is a so-called three-phase AC motor, and has a U phase, a V phase, and a W phase. In this embodiment, the torque generated by the motor 3 generates a driving force for the drive wheels of the vehicle. In other words, the motor 3 is a driving source for the vehicle. The motor control system 100 can also perform regenerative control of the motor 3 as necessary when the vehicle is decelerating, etc. In this case, the motor 3 generates a braking force for the vehicle. Depending on the vehicle, the motor 3 may be used as a motor generator (MG) instead of being used as a driving source.

[0017] The vehicle controller 4 is a computer for comprehensively controlling the operation of the vehicle and the operation of the motor control system 100. The vehicle controller 4 is composed of, for example, a central processing unit (CPU), a random access memory (RAM), and an input / output interface (I / O interface). The vehicle controller 4 is also programmed to periodically execute the functions of the motor control system 100 at a predetermined control period.

[0018] The vehicle controller 4 outputs a control signal for the motor control system 100 to drive the motor 3 in response to, for example, the accelerator opening Apo of the vehicle. * By inputting this, the motor 3 generates a torque according to a demand determined by the accelerator opening Apo and the like.

[0019] In addition to driving the motor 3 as described above, the motor control system 100 also functions as a charging control system that charges the battery 1 with an external power supply 5. For this reason, the motor control system 100 includes an external power supply terminal 6, which is a connection terminal for connecting the external power supply 5, and a DC / DC converter 7.

[0020] The external power source 5 is a commercial AC power source. In this embodiment, the external power source 5 is a single-phase AC power source, for example, a 100-V power source or a 200-V power source.

[0021] The external power supply terminal 6 connects the external power supply 5 to the battery 1 via the inverter 2 when the battery 1 is charged by the external power supply 5. As a result, in the motor control system 100, when the battery 1 is charged by the external power supply 5, the inverter 2 for driving the motor is used as a power factor correction (PFC) circuit. The external power supply terminal 6 also includes a first terminal 6a and a second terminal 6b. The first terminal 6a is connected to the hot side (ungrounded side) of the external power supply 5, and the second terminal 6b is connected to the cold side (grounded side) of the external power supply 5.

[0022] The DC / DC converter 7 functions as a step-down chopper when the battery 1 is charged by the external power supply 5. That is, the DC / DC converter 7 steps down the DC power input from the inverter 2 to a voltage suitable for charging the battery 1 and supplies the voltage to the battery 1. In this embodiment, the DC / DC converter 7 is a so-called isolated type.

[0023] As described above, the motor control system 100 operates in an operation mode in which the motor 3 is driven (hereinafter referred to as the motor drive mode) or in an operation mode in which the battery 1 is charged by the external power supply 5 (hereinafter referred to as the charge operation mode). The motor control system 100 shares the inverter 2 when operating in the motor drive mode (hereinafter referred to as the motor drive mode) and when operating in the charge operation mode (hereinafter referred to as the charge operation mode).

[0024] Switching between the motor drive mode and the charging operation mode is performed by operating the relay 8 or the like.

[0025] The relay 8 is a switch that switches the connection state of the inverter 2, the DC / DC converter 7, and the battery 1. When the relay 8 is on, the battery 1 is substantially connected directly (in series) to the inverter 2 without going through the DC / DC converter 7. When the relay 8 is off, the battery 1 is connected to the inverter 2 via the DC / DC converter 7. For this reason, the relay 8 is turned on when the motor is driven and turned off during charging operation. The on / off (opening / closing) of the relay 8 is controlled by a relay drive signal S RD Therefore, the relay drive signal S RD is a signal for switching the operation mode of the motor control system 100. Note that the relay drive signal S RD is output by the vehicle controller 4 in response to, for example, detection of connection or disconnection of the external power supply 5. The connection or disconnection of the external power supply 5 is performed, for example, by a detector or the like (not shown).

[0026] <Inverter configuration> As shown in FIG. 1, the inverter 2 includes power modules 10u to 10w, a drive circuit 11, and a control circuit 12.

[0027] The power modules 10u to 10w form a pair of upper and lower arms for each phase of the motor 3. More specifically, the power module 10u is a leg connected to the U-phase of the motor 3. The power module 10u includes an upper arm made up of a switching element Tr1 and a freewheel diode D1, and a lower arm made up of a switching element Tr2 and a freewheel diode D2. Similarly, the power module 10v is a leg connected to the V-phase of the motor 3, and includes an upper arm made up of a switching element Tr3 and a freewheel diode D3, and a lower arm made up of a switching element Tr4 and a freewheel diode D4. The power module 10w is a leg connected to the W-phase of the motor 3, and includes an upper arm made up of a switching element Tr5 and a freewheel diode D5, and a lower arm made up of a switching element Tr6 and a freewheel diode D6. The switching elements Tr1 to Tr6 are, for example, semiconductor switches such as IGBTs (Insulated Gate Bipolar Transistors). In principle, one of the upper arm and lower arm that make up one leg is turned on and the other is turned off depending on the polarity of the AC power.

[0028] The power modules 10u to 10w control the timing of opening and closing the switching elements Tr1 to Tr6 according to the waveform of the input power. As a result, when the input power is AC, the power modules 10u to 10w rectify (forward convert) the input power to DC when the input power is AC, and inversely convert the input power to AC when the input power is DC. In the motor drive mode, the power modules 10u to 10w convert the DC power input from the battery 1 to three-phase AC power and input it to each phase (U phase, V phase, and W phase) of the motor 3. On the other hand, in the charging operation mode, the power modules 10u to 10w rectify the AC power input from the external power source 5 to DC power and input it to the battery 1.

[0029] The drive circuit 11 is a circuit for driving the switching elements Tr1 to Tr6, and controls the on / off of each of the switching elements Tr1 to Tr6. The drive circuit 11 also receives a pulse width modulation signal (PWM signal) from the control circuit 10. The drive circuit 11 then turns the switching elements Tr1 to Tr6 on or off at a duty ratio determined by the PWM signal.

[0030] In this embodiment, the drive circuit 11 also functions as an input power detection circuit that detects the input power from the battery 1 and the external power source 5. Specifically, the drive circuit 11 detects the DC voltage V applied from the battery 1 to the power modules 10u to 10w. DC In addition, the drive circuit 11 detects the AC voltage V applied to the power modules 10u to 10w from the external power source 5. AC Detects the DC voltage V DC and / or AC voltage V AC is input to the control circuit 12.

[0031] The control circuit 12 generates a PWM signal that controls the on / off of the switching elements Tr1 to Tr6. The control circuit 12 inputs the generated PWM signal to the drive circuit 11.

[0032] More specifically, when the motor is driven, the control circuit 12 outputs a torque command T * , the currents flowing through each phase of the motor 3 (hereinafter referred to as phase currents) iu, iv, and iw, and the DC voltage V DC , and a rotor position signal Rpos indicating the position of the rotor of the motor 3. According to this PWM signal, the motor 3 is driven in response to a torque command T * The current flowing through each phase of the motor 3 is detected (sampled) by a current sensor 13 provided for each phase. A rotor position signal Rpos indicating the position of the rotor of the motor 3 is detected by a resolver 14.

[0033] During charging operation, the control circuit 12 controls the phase currents iu, iv, and iw of each phase and the AC voltage V ACAccording to this PWM signal, the battery 1 is charged by AC power input from the external power supply 5.

[0034] As described above, the control circuit 12 is a controller (control device) that controls the driving of the motor 3 and the charging of the battery 1. In other words, the control circuit 12 is a drive control device that controls the driving of the motor 3, and also a charge control device that controls the charging of the battery 1 by the external power supply 5. The control circuit 12 may be configured by a computer including, for example, a central processing unit (CPU), a random access memory (RAM), an input / output interface (I / O interface), and the like. In this case, the control circuit 12 is programmed to periodically execute the operation of the inverter 2 in the motor drive mode and the charging mode at a predetermined control period.

[0035] In addition to the above, in order to charge the battery 1, the inverter 2 includes a smoothing capacitor 21, a relay 22, a reactor 23, a filter capacitor 24, an EMI (Electro Magnetic Interference) filter 25, and a relay 26.

[0036] The smoothing capacitor 21 smoothes the DC power obtained by rectifying the AC power input from the external power source 5 using the power modules 10u to 10w. The smoothing capacitor 21 is connected between the power modules 10u to 10w and the battery 1 in parallel with them. The smoothing capacitor 21 is composed of, for example, two capacitors 21a and 21b connected in series with each other. An intermediate potential point 21c of the capacitors 21a and 21b is connected to the cold side of the external power source 5, i.e., the second terminal 6b.

[0037] The relay 22 is a switch that controls the connection between each phase of the motor 3 and the hot side of the external power supply 5. In this embodiment, a relay 22 is provided for each phase. Moreover, the on / off of the relay 22 is controlled by a relay drive signal (not shown) input from the vehicle controller 4. The relay 22 is turned off when the motor is driven and turned on when charging.

[0038] The reactor 23 is connected in series to the hot side of the external power supply 5. Furthermore, the filter capacitor 24 is connected in parallel to the external power supply 5. An LC circuit consisting of the reactor 23 and the filter capacitor 24 removes noise generated by the on / off of the switching elements Tr1 to Tr6 during charging operation. The EMI filter 25 suppresses the generation and intrusion of electromagnetic noise at the external power supply terminal 6. The drive circuit 11 detects the AC voltage V AC Detect.

[0039] The relay 26 is a switch provided on the cold side of the external power supply 5. The relay 26 is provided between the intermediate potential point 21c of the smoothing capacitor 21 and the second terminal 6b. The on / off of the relay 26 is controlled by a relay drive signal (not shown) input from the vehicle controller 4. The relay 26 is turned off when the motor is driven and turned on when the charging operation is performed.

[0040] FIG. 2 is an explanatory diagram showing the relationship between the operation mode, the on / off state of the relay, and the switching frequency. As shown in FIG. 2, for example, the vehicle is started to be driven at time t1, and the vehicle is stopped at time t2. In this case, the motor control system 100 operates in the motor drive mode during the period from time t1 to time t2 during which the vehicle is driven. Therefore, the relay 8 on the DC power supply side (i.e., the battery 1 side) is turned on, and the relays 22, 26 on the AC power supply side (i.e., the external power supply terminal 6 side) are turned off. In the motor drive mode, the switching frequency of the power modules 10u to 10w is lower than that in the charging operation mode. This is to reduce the power loss in the inverter 2 and the motor 3 during motor drive. In this embodiment, the switching frequency in the motor drive mode is, for example, about 10 kHz.

[0041] Also, assume that at time t3 after the operation is completed, the external power source 5 is connected to start charging, and charging is completed at a later time t4 (see FIG. 2). In this case, during the period from time t3 to time t4 when the battery 1 is being charged, the motor control system 100 operates in the charging operation mode. Therefore, the relay 8 on the DC power supply side is turned off, and the relays 22, 26 on the AC power supply side are turned on. In addition, in the charging operation mode, the switching frequency of the power modules 10u to 10w is higher than that in the motor drive mode.

[0042] FIG. 3 is a graph showing static characteristics of the switching elements Tr1 to Tr6. As shown in FIG. 3, the maximum current Ic1 and maximum voltage Vec(sat)1 during charging operation are smaller than the maximum current Ic2 and maximum voltage Vec(sat)2 during motor driving. Therefore, during charging operation, the operating points of the power modules 10u to 10w have a sufficient margin for their capabilities. Therefore, during charging operation, even if the switching frequency is increased, the power factor correction operation of the inverter 2 can be performed with low loss. Therefore, as described above, in the charging operation mode, the switching frequency is set higher than that in the motor driving mode. In this embodiment, the switching frequency in the charging operation mode is, for example, about 60 kHz (see FIG. 2).

[0043] When the vehicle is not being driven and the battery 1 is not being charged, the relay 8 on the DC power supply side and the relays 22 and 26 on the AC power supply side are both off (see FIG. 2).

[0044] 4A is a timing chart showing the basic transition of the phase voltage and the line voltage when the motor is driven and when the motor is charged. As shown in FIG. 4A, when the motor is driven, the control circuit 12 outputs a torque command T *In response to the above, the control circuit 12 controls the voltages Vu, Vv, and Vw applied to each phase (hereinafter referred to as phase voltages) so that the motor 3 generates the required torque. That is, the control circuit 12 transitions the phase voltages Vu, Vv, and Vw of each phase. As a result, the line voltages Vu-v, Vu-w, and Vw-u of each phase transition as shown in the figure. Note that the horizontal axis in FIG. 4 represents time, and the period indicated by the dashed dotted line is the control period of the motor control system 100.

[0045] On the other hand, during charging operation, the control circuit 12 performs synchronization control to synchronize the operation timing of turning on and / or off the multiple switching elements Tr1 to Tr6. Therefore, as shown in Fig. 4(B), during charging operation, the control circuit 12 synchronizes the phase voltages Vu, Vv, and Vw of each phase. As a result, in an ideal system in which there is no individual difference in the switching elements Tr1 to Tr6, the line voltages Vu-v, Vu-w, and Vw-u of each phase are all zero.

[0046] FIG. 5 is a timing chart showing the operation timing of the switching elements Tr1 to Tr6, the phase voltages Vu, Vv, Vw, and the phase currents iu, iv, iw during charging operation when there is no individual difference between the switching elements. The horizontal axis in FIG. 5 is time, and the cycle shown by the dashed line is the control cycle of the motor control system 100. As shown in FIG. 5, the switching elements Tr1 to Tr6 are controlled to be on or off synchronously. However, the synchronous control of the switching elements Tr1 to Tr6 includes a dead time period DT. The dead time period DT is a period during which both of the switching elements Tr1 to Tr6 forming the upper arm and the lower arm are off. The dead time period DT is provided to prevent each of the power modules 10u to 10w from being short-circuited. That is, in the above-mentioned synchronous control, the upper arm (Tr1, Tr3, Tr5) are turned on / off at the same timing, and the lower arm (Tr2, Tr4, Tr6) are turned on / off at the same timing. However, in order to provide the dead time period DT, the upper arm (Tr1, Tr3, Tr5) and the lower arm (Tr2, Tr4, Tr6) are turned on / off at different timings, strictly speaking. Therefore, the "synchronization" in the above synchronous control includes the necessity of providing the dead time period DT. In other words, with respect to the relationship between the upper arm and the lower arm, the "synchronization" in the above synchronous control means driving the switching elements Tr1 to Tr6 simultaneously or sequentially within a predetermined time range (before and after the dead time period DT).

[0047] According to the synchronous control, the phase voltages Vu, Vv, and Vw of each phase rise and fall at the same timing. That is, with respect to the interrelationship between the power modules 10u to 10w, the "synchronization" in the synchronous control means that the phase voltages Vu, Vv, and Vw of each phase rise and fall at the same timing. According to the "synchronization" in which the phase voltages Vu, Vv, and Vw of each phase rise and fall at the same timing, in an ideal system in which there is no individual difference in the switching elements Tr1 to Tr6, the phase currents iu, iv, and iw of each phase rise or fall in the same manner. At this time, since each phase of the motor 3 has an equipotential, no circulating current circulating between the phases occurs. Therefore, the synchronous control is a control for preventing the generation of a circulating current during a charging operation. In an ideal system in which there is no individual difference in the switching elements Tr1 to Tr6, the operation timing of the switching elements Tr1 to Tr6 shown in FIG. 5 is substantially the same as the PWM signal. Hereinafter, a PWM signal when there is no individual difference among the switching elements Tr1 to Tr6 is referred to as a basic PWM signal, and a pulse width determined by the basic PWM signal is referred to as a basic pulse width. The operation timing of the switching elements Tr1 to Tr6 is substantially the same as that shown in FIG. 5, so the illustration of the basic PWM signal is omitted.

[0048] 6 is a timing chart showing the operation timing of switching elements Tr1 to Tr6, phase voltages Vu, Vv, Vw, and phase currents iu, iv, iw during charging when there is individual difference between switching elements. The horizontal axis of FIG. 6 represents time, and the cycle indicated by the dashed line is the control cycle of the motor control system 100.

[0049] 6, when switching element Tr2 switches from on to off (when it turns off), it has an individual characteristic that it is delayed relatively more than other switching elements Tr1, Tr3 to Tr6 with respect to the input basic PWM signal. Also, when switching element Tr2 switches from off to on, there is no delay, and the other switching elements Tr1, Tr3 to Tr6 have no delay in switching on / off.

[0050] In this case, due to a switching delay of the switching element Tr2, a delay also occurs in the rise of the phase voltage Vu, as shown by the arrow A2. Therefore, in the portion where the switching of the switching element Tr2 is delayed, the line voltages Vu-v, Vu-w, and Vw-u of each phase are no longer zero (not shown). As a result, due to a switching delay of the switching element Tr2, as shown by the arrow A3, the current amount of the phase current iu temporarily increases. Also, as shown by the arrows A4 and A5, the current amounts of the phase currents iv and iw temporarily decrease. In other words, current concentration occurs in the U phase.

[0051] 7 is an explanatory diagram showing the operation during the dead time period DT when a specific switching element Tr2 (A) has no delay in turning off and (B) has a delay in turning off. As shown in FIG. 7(A), when there is no delay in turning off the switching elements Tr1-Tr6 due to individual differences, all the switching elements Tr1-Tr6 of the power modules 10u-10w are turned off in synchronization during the dead time period DT. Therefore, the power supplied from the external power source 5 is not consumed.

[0052] On the other hand, as shown in Fig. 7(B), assume that there is a delay in turning off the switching element Tr2 due to individual differences, as in the example of Fig. 6. In this case, as shown by the hatched arrow, even during the dead time period DT, power supplied from the external power supply 5 leaks through the switching element Tr2, and a U-phase current iu is generated. The generation of this U-phase current iu is the above-mentioned current concentration.

[0053] In this way, the current that increases or decreases due to current concentration is a circulating current that flows between the phases and does not contribute to charging the battery 1. For this reason, if there is a switching delay in the switching element Tr2 as described above, the charging efficiency will deteriorate. Here, an example has been described in which there is a switching delay when the switching element Tr2 switches from on to off, but the same applies when there is a switching delay when the switching element Tr2 switches from off to on (when turning on). The same applies when there is a switching delay in switching on / off the other switching elements Tr1, Tr3 to Tr6.

[0054] <Phase current detection timing> Therefore, whereas the conventional timing for detecting phase currents iu, iv, iw is, for example, the start of a control period, such as detection timing T1, in this embodiment, the control circuit 12 changes the timing for detecting phase currents iu, iv, iw. Specifically, the control circuit 12 detects phase currents iu, iv, iw at timing T2 when switching elements Tr1 to Tr6 are turned on and / or off. This is in order to detect the above-mentioned circulating current. Note that, at conventional detection timing T1 for phase currents iu, iv, iw, the above-mentioned current concentration and circulating currents due to current concentration (hereinafter simply referred to as circulating currents) are not detected.

[0055] Timing T2 is the timing at which a circulating current circulating between each phase occurs. That is, timing T2 is, for example, immediately after the switching elements Tr1 to Tr6 are turned on and / or off. When there is an individual difference in the operation timing of the switching elements Tr1 to Tr6, the circulating current can be almost certainly detected immediately after the switching elements Tr1 to Tr6 are turned on and / or off. Note that "immediately after" the switching elements Tr1 to Tr6 are turned on and / or off refers to a period during which a circulating current occurs depending on the individual difference of the switching elements Tr1 to Tr6. More specifically, the control circuit 12 detects the phase currents iu, iv, and iw at least during the dead time period DT.

[0056] <Correction of switching element operation timing> Then, the control circuit 12 corrects the operation timing of any of the switching elements Tr1-Tr6 based on the detected phase currents iu, iv, and iw of each phase. This correction of the operation timing of the switching elements Tr1-Tr6 adjusts the timing at which any of the switching elements Tr1-Tr6 is turned on or off, taking into account switching delays caused by individual differences. Therefore, as a result of this correction, even if there are switching delays caused by individual differences in the switching elements Tr1-Tr6, all of the switching elements Tr1-Tr6 are turned on / off synchronously at the expected timing.

[0057] The control circuit 12 performs correction related to the operation timing of the switching elements Tr1 to Tr6 so as to reduce the variation of the phase currents iu, iv, and iw of each phase. More specifically, the control circuit 12 calculates an average value iav of the absolute values ​​|iu|, |iv|, and |iw| (not shown) of the phase currents iu, iv, and iw of each phase. Then, the control circuit 12 calculates the difference between the absolute values ​​|iu|, |iv|, and |iw| of the phase currents of each phase and this average value iav. That is, the U-phase difference Δiu=iav-|iu|, the V-phase difference Δiv=iav-|iv|, and the W-phase difference Δiw=iaw-|iw| are calculated, respectively. These phase differences Δiu, Δiv, and Δiw represent the variation of the phase currents iu, iv, and iw of each phase. That is, the occurrence timing (timing when each phase difference Δiu, Δiv, Δiw becomes non-zero) and the occurrence amount correspond to the relative delay or advance of the switching of the switching elements Tr1 to Tr6. Therefore, the control circuit 12 corrects the operation timing of the switching elements Tr1 to Tr6 so as to make each phase difference Δiu, Δiv, Δiw zero.

[0058] In this embodiment, since the switching elements Tr1 to Tr6 are driven using PWM signals, the control circuit 12 corrects the operation timing of the switching elements Tr1 to Tr6 by adjusting the pulse width determined by the basic PWM signal. The pulse width of the basic PWM signal determines the period during which the switching elements Tr1 to Tr6 are turned on and / or off for each control cycle. The adjustment of the pulse width of the basic PWM signal is performed for each of the switching elements Tr1 to Tr6.

[0059] For example, in the examples of Fig. 6 and Fig. 7, the control circuit 12 makes the pulse width of the basic PWM signal input to the switching element Tr2 longer than the pulse widths of the other switching elements Tr1, Tr3 to Tr6. Also, in the examples of Fig. 6 and Fig. 7, the control circuit 12 generates a PWM signal (hereinafter referred to as a corrected PWM signal) having a pulse width (adjusted pulse width) obtained by adjusting the pulse width (basic pulse width) of the basic PWM signal input to the switching element Tr2 so that the initial edge of the pulse input to the switching element Tr2 is earlier than the initial edge of the pulse input to the other switching elements Tr1, Tr3 to Tr6. Also, the adjustment of the pulse width of the PWM signal input to the switching element Tr2 is performed so as to make each phase difference Δiu, Δiv, Δiw zero according to the timing and amount at which each phase difference Δiu, Δiv, Δiw appears. Then, the control circuit 12 drives the switching element Tr2 by the corrected PWM signal.

[0060] 6 and 7, the operation timing of the switching element Tr2 is corrected as described above, but in reality, there are various individual differences in the switching of the switching elements Tr1 to Tr6. Therefore, when there is an individual difference in the operation timing of any one or more of the switching elements Tr1 to Tr6, the operation timing of one or more of the switching elements Tr1 to Tr6 is corrected.

[0061] <Charging operation mode> Hereinafter, the operation of motor control system 100 configured as above in the charging operation mode will be described.

[0062] FIG. 8 is a flowchart showing the operation of the charging operation mode. As shown in FIG. 8, when the charging operation mode starts, in step S101, the on / off of the switching elements Tr1 to Tr6 is synchronized. Then, in step S102, the timing at which the synchronized switching elements Tr1 to Tr6 are turned on or off is monitored. Then, if it is immediately after the on / off of the switching elements Tr1 to Tr6 in this step S102, the phase currents iu, iv, and iw are detected in step S103. Then, in step S104, the variations of the detected phase currents iu, iv, and iw (phase differences Δiu, Δiv, and Δiw) are calculated. Then, in step S105, the basic PWM signal is corrected based on the calculated variations of the phase currents iu, iv, and iw, and in step S106, the power modules 10u to 10w are driven by the corrected PWM signal.

[0063] As described above, the charge control method according to the present embodiment is executed in a motor control system 100 that drives a motor 3 having multiple phases (U phase, V phase, and W phase) with power supplied from a battery 1 via an inverter 2 having multiple switching elements Tr1 to Tr6, and connects an external power source 5 to the battery 1 via the inverter 2 when charging the battery 1 with the external power source 5. In this charge control method, when charging the battery 1 with the external power source 5, a synchronous control is performed to synchronize the operation timings of turning on and / or off the multiple switching elements Tr1 to Tr6. Then, at the timing when a circulating current circulating between the phases (U phase, V phase, and W phase) occurs and at the timing when the multiple switching elements Tr1 to Tr6 are turned on or off, phase currents iu, iv, and iw, which are currents flowing through each phase of the motor 3, are detected, and the operation timings of one or more of the multiple switching elements Tr1 to Tr6 are corrected based on the detected phase currents iu, iv, and iw of each phase.

[0064] By correcting the operation timing of the switching elements Tr1 to Tr6 as described above, the timing at which the switching elements Tr1 to Tr6 actually operate can be more reliably synchronized, taking into account individual differences. This suppresses the generation of circulating current circulating between the phases. As a result, the power input from the external power source 5 is not wasted as a circulating current, improving charging efficiency. In other words, when there are individual differences in the timing at which the switching elements Tr1 to Tr6 actually operate with respect to the basic PWM signal input in synchronization, correcting the operation timing as described above allows the external power source 5 to charge the battery 1 efficiently.

[0065] In the motor control system 100 according to this embodiment, a pair of an upper arm and a lower arm is formed for each phase of the motor 3. The synchronous control of the switching elements Tr1 to Tr6 in the charging operation mode includes a dead time period DT during which both the upper arm and the lower arm are turned off. In the charging control method according to this embodiment, the phase currents iu, iv, and iw are detected at least during this dead time period DT.

[0066] In this way, by detecting the phase currents iu, iv, and iw during the dead time period DT, the circulating currents generated due to the individual differences of the switching elements Tr1 to Tr6 are detected more reliably. As a result, the operation timings of the switching elements Tr1 to Tr6 are corrected more reliably, and the battery 1 can be charged particularly efficiently by the external power source 5.

[0067] In addition, in the charge control method according to the present embodiment, the operation timings of the switching elements Tr1 to Tr6 are corrected so as to reduce the variation in the phase currents iu, iv, and iw of each phase. The variation in the phase currents iu, iv, and iw corresponds to the relative delay or advance of the switching of the switching elements Tr1 to Tr6. Therefore, by correcting the operation timings of the switching elements Tr1 to Tr6 so as to reduce the variation in the phase currents iu, iv, and iw of each phase as described above, the operation timings of the switching elements Tr1 to Tr6 are corrected particularly accurately. As a result, the battery 1 can be charged particularly efficiently by the external power source 5.

[0068] In addition, in the charge control method according to the present embodiment, the operation timing of the switching elements Tr1 to Tr6 is corrected by calculating the average value iav of the phase currents iu, iv, and iw of each phase, calculating the difference (Δiu, Δiv, Δiw) between the average value iav and the phase currents iu, iv, and iw as the variation of the phase currents iu, iv, and iw for each of a plurality of phases (U phase, V phase, and W phase), and making these differences (Δiu, Δiv, Δiw) zero. The occurrence timing and the occurrence amount of each phase difference Δiu, Δiv, Δiw well represent the relative delay or advance of the switching of the switching elements Tr1 to Tr6. Therefore, as described above, when the operation timing of the switching elements Tr1 to Tr6 is corrected so as to make each phase difference Δiu, Δiv, Δiw zero, the operation timing of the switching elements Tr1 to Tr6 is corrected particularly accurately. As a result, the battery 1 can be charged particularly efficiently by the external power source 5.

[0069] In the motor control system 100 according to this embodiment, the switching elements Tr1 to Tr6 are driven using a PWM signal. Therefore, in the charge control method according to this embodiment, the operation timing of the switching elements Tr1 to Tr6 is corrected by adjusting the pulse width (basic pulse width) determined by the PWM signal (basic PWM signal) so that the phase differences Δiu, Δiv, and Δiw become zero. By adjusting the pulse width in this manner, even if there is an individual difference between the switching elements Tr1 to Tr6, this individual difference can be absorbed and the actual operation timing of the switching elements Tr1 to Tr6 can be synchronized. As a result, the battery 1 can be efficiently charged by the external power source 5.

[0070] In the above embodiment, one example of the circuit configuration of the motor control system 100 is shown (see FIG. 1), but the specific circuit configuration of the motor control system 100 is not limited to this.

[0071] FIG. 9 is a block diagram showing a modified circuit configuration of the motor control system. In the motor control system 200 shown in FIG. 9, instead of connecting the hot side of the external power supply 5 to each phase of the motor 3, the hot side of the external power supply 5 is connected to the neutral point 3c of the motor 3. This reduces the number of relays 22 to one. In addition, the reactor 23 for PFC is omitted. This is because the zero-phase inductance of the motor 3 is used for PFC. The rest of the configuration is the same as that of the motor control system 100 of the above embodiment. The motor control system 200 configured in this way can also implement a charging operation mode similar to that of the above embodiment. In addition, there is an advantage that the number of parts and costs can be reduced compared to the motor control system 100 of the embodiment.

[0072] Fig. 10 is a block diagram showing a modified example of the circuit configuration of the motor control system. In the motor control system 300 shown in Fig. 10, the insulated DC / DC converter 7 is replaced with a non-insulated bidirectional DC / DC converter 301. As a result, the number of relays 8 is reduced to one. The rest of the configuration is the same as that of the motor control system 100 of the above embodiment.

[0073] DC / DC converter 301 is composed of, for example, a reactor 302 and a power module. The power module constituting DC / DC converter 301 is formed by an upper arm composed of a switching element Tr7 and a freewheel diode D7, and a lower arm composed of a switching element Tr8 and a freewheel diode D8.

[0074] The motor control system 300 configured in this manner can also implement a charging operation mode similar to that of the above embodiment. The DC / DC converter 301 functions as a step-down chopper during charging operation, similar to that of the above embodiment, and also functions as a step-up converter when driving the motor. This has the advantage that the output of the motor 3 is improved when driving the motor.

[0075] FIG. 11 is a block diagram showing a modified circuit configuration of the motor control system. The motor control system 400 shown in FIG. 11 has a circuit configuration when the external power supply 5 is a three-phase AC power supply. In the motor control system 400, the u-phase of the external power supply 5 is connected to a first terminal 6a, and the w-phase of the external power supply 5 is connected to a second terminal 6b. A third terminal 6c for connecting the v-phase of the external power supply 5 is added to the external power supply terminal 6. The reactors 23 are provided in each phase of the external power supply 5, and the filter capacitors 24 are provided between the uv and vw phases of the external power supply 5 to form an LC filter. The relays 26 are provided in the v and w phases of the external power supply 5. In addition, for example, the current sensor 13 in the W-phase of the motor 3 is omitted, and instead, a new current sensor 401 is added to the v-phase of the external power supply 5. During motor driving, the control circuit 12 calculates the W-phase current iw from the U-phase and V-phase phase currents iu, iv of the motor 3, and during charging, it refers to the v-phase current (not shown) of the external power source 5 detected by the current sensor 401.

[0076] Furthermore, in the motor control system 400, in addition to the power modules 10u to 10w, a power module 402 is added and connected to the v-phase of the external power source 5. The power module 402 is composed of an upper arm consisting of a switching element Tr9 and a freewheeling diode D9, and a lower arm consisting of a switching element Tr10 and a freewheeling diode D10. The power module 402 is operated during charging operation, but is not operated during motor driving. For this reason, the power module 402 only needs to withstand the current and voltage required during charging operation (see FIG. 3), and may be smaller in size than the power modules 10u to 10w. The w-phase of the external power source 5 is connected to the intermediate potential point 21c of the smoothing capacitor 21, as in the motor control system 100 of the embodiment.

[0077] In the motor control system 400 configured in this manner, a three-phase AC power supply can also be used as the external power supply 5, and a charging operation mode similar to that of the above embodiment can be implemented.

[0078] The above describes the embodiments and modifications of the present invention. However, the configurations described in the above embodiments and modifications merely illustrate some of the application examples of the present invention and are not intended to limit the technical scope of the present invention. [Explanation of symbols]

[0079] 1: Battery 2: Inverter 3: Motor 4: Vehicle controller 5: External power supply 7: DC / DC converter 10u~10w: Power module 11: Drive circuit 12: Control circuit 21: Smoothing capacitor

Claims

1. 1. A charge control method executed in a motor control system in which a motor having multiple phases is driven by power supplied from a battery via an inverter having multiple switching elements, and an external power supply is connected to the battery via the inverter when charging the battery from the external power supply, comprising: performing synchronous control to synchronize the operation timings of turning on and / or off the plurality of switching elements when charging the battery by the external power supply; Detecting a phase current, which is a current flowing through each phase of the motor, at a timing when a circulating current circulating between the phases occurs; correcting the operation timing of one or more of the switching elements among the plurality of switching elements based on the detected phase current of each phase; Charging control method.

2. 2. The charge control method according to claim 1, The switching elements form a pair of an upper arm and a lower arm for each phase, the synchronous control includes a dead time period during which the upper arm and the lower arm are both off; The detection of the phase current is performed at least during the dead time period. Charging control method.

3. The charge control method according to claim 1 or 2, The operation timing is corrected to reduce the variation in the phase current of each phase. Charging control method.

4. The charge control method according to claim 3, The correction of the operation timing is Calculating an average value of the phase current for each phase; calculating, for each of the plurality of phases, a difference between the average value and the phase current as the variation; The difference is set to zero. Charging control method.

5. The charge control method according to claim 4, Driving a plurality of said switching elements with pulse width modulated signals; The correction of the operation timing is performed by adjusting a pulse width determined by the pulse width modulation signal so that the difference becomes zero. Charging control method.

6. A motor control system drives a motor having multiple phases with power supplied from a battery via an inverter having multiple switching elements, and connects an external power supply to the battery via the inverter when charging the battery from the external power supply, comprising: a charge control device that controls charging of the battery by the external power supply, performing synchronous control to synchronize the operation timings of turning on and / or off the plurality of switching elements when charging the battery by the external power supply; Detecting a phase current, which is a current flowing through each phase of the motor, at a timing when a circulating current circulating between the phases occurs; correcting the operation timing of one or more of the switching elements among the plurality of switching elements based on the detected phase current of each phase; Charging control device.

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